Evolución del coeficiente de Poisson de un hormigón autocompactante reforzado con fibras de acero

En este trabajo se estudia la variación de la edad y el nivel de carga del coeficiente de Poisson de un hormigón autocompactante reforzado con fibras de acero (HACRFA) fabricado por la empresa Lafarge-Holcin

Femto-LASIK after Deep Anterior Lamellar Keratoplasty to Correct Residual Astigmatism: A Long-Term Case Series Study

Purpose: To evaluate the long-term outcomes of femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) to correct residual astigmatism after deep anterior lamellar keratoplasty (DALK). Methods: This retrospective case series study included 10 eyes that underwent Femto-LASIK after a DALK. The refractive error, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, thinnest corneal thickness (TCT), and central corneal thickness (CCT) were registered. The postoperative follow-up ranged between 36 and 60 months. Results: All surgeries were uneventful, with no intra- or postoperative complications. The mean UDVA (Snellen scale) rose from 0.13 ± 0.05 to 0.47 ± 0.15 six months after Femto-LASIK (p < 0.001). All cases experienced a significant improvement in UDVA. None of the eyes lost lines of CDVA, and seven eyes (70%) improved the CDVA compared to preoperative values. The refractive cylinder changed from a preoperative value of −3.88 ± 1.00 D to −0.93 ± 0.39 six months after Femto-LASIK (p < 0.0001). In eight eyes (80%), the UDVA and refractive outcomes remained stable at postoperative follow-up visits. In contrast, one eye experienced a refractive regression over the follow-up. TCT and CCT were stable at the different postoperative follow-up visits. Conclusions: Our findings suggest that Femto-LASIK might safely and effectively corrects residual astigmatism after DALK. Despite these encouraging results, further long-term studies, including a larger number of cases, are required to confirm the safety of the procedure. The refractive stability in eyes with prior RK might be lower than for other DALK indications.Depto. de Optometría y VisiónFac. de Óptica y OptometríaTRUEpu

Evolución del módulo de elasticidad de un hormigón autocompactante reforzado con fibras de acero

En este trabajo se han ensayado a compresión hasta rotura probetas de un HACRFA fabricado por Lafarge-Holci

Caracterización mecánica de hormigones autocompactantes reforzados con fibras de acero

El hormigón autocompactante reforzado con fibras de acero presenta simultáneamente las ventajas de los hormigones autocompactantes y de los reforzados con fibras. Se consigue un material de altas prestaciones con mayor tenacidad y ductilidad. En este trabajo se ha estudiado el comportamiento mecánico de un hormigón autocompactante reforzado con fibras de acero. Se han realizado ensayos a compresión, tracción y flexión a distintas edades; así como ensayos no destructivos (medida de la velocidad de ultrasonidos e índice esclerométrico). Los resultados muestran la variación de la respuesta del hormigón con el tiempo y la diferencia existente con hormigones tradicionales

Pérdidas de fruto y movilización de semillas en olea europaea var. Sylvestris brot. (oleaceae)

Se analizan varios aspectos de la biología de reproducción del acebuche [Olea europaea var. sylvestris Brot. (Oleaceae)] relacionados con la dispersión de semillas. Se compara el éxito de remoción en dos habitat -uno en dos temporadas- y se analizan las similitudes y diferencias en las causas de pérdidas de frutos por agentes bióticos y abióticos. En general, el esfuerzo de producción de fruto fue poco recompensado, ya que el éxito de remoción fue bajo. Las pérdidas totales de fruto variaron considerablemente entre años, pero aparentemente no limitaron la dispersión de semillas. Los agentes abióticos causaron más pérdidas que los bió- ticos. Al final de la temporada permanecían muchos frutos en las ramas, lo que sugiere que la cantidad de dispersantes fue limitante para el éxito de remoción. La importancia relativa de la remoción y de cada tipo de pérdida permaneció constante entre habitat y tendió a mantenerse entre individuos. En conclusión, aunque el porcentaje de remoción fue bajo, los resultados sugieren que el éxito de la función de fructificación de los acebuches en estas parcelas dependió fundamentalmente de la acción de los dispersantes

Electrohydrodynamic Processing of PVP-Doped Kraft Lignin Micro- and Nano-Structures and Application of Electrospun Nanofiber Templates to Produce Oleogels

The present work focuses on the development of lignin micro- and nano-structures obtained by means of electrohydrodynamic techniques aimed to be potentially applicable as thickening or structuring agents in vegetable oils. The micro- and nano-structures used were mainly composed of eucalyptus kraft lignin (EKL), which were doped to some extent with polyvinylpyrrolidone (PVP). EKL/PVP solutions were prepared at different concentrations (10–40 wt.%) and EKL:PVP ratios (95:5–100:0) in N, N-dimethylformamide (DMF) and further physico-chemically and rheologically characterized. Electrosprayed micro-sized particles were obtained from solutions with low EKL/PVP concentrations (10 and 20 wt.%) and/or high EKL:PVP ratios, whereas beaded nanofiber mats were produced by increasing the solution concentration and/or decreasing EKL:PVP ratio, as a consequence of improved extensional viscoelastic properties. EKL/PVP electrospun nanofibers were able to form oleogels by simply dispersing them into castor oil at nanofiber concentrations higher than 15 wt.%. The rheological properties of these oleogels were assessed by means of small-amplitude oscillatory shear (SAOS) and viscous flow tests. The values of SAOS functions and viscosity depended on both the nanofiber concentration and the morphology of nanofiber templates and resemble those exhibited by commercial lubricating greases made from traditional metallic soaps and mineral oilsThis work is part of a research project (Ref. RTI2018-096080-B-C21) sponsored by the MICINN-FEDER I+D+i Spanish Programme. The authors gratefully acknowledge their financial support. J.F.R.-V. acknowledges receiving the Ph.D. Research Grant PRE2019-090632 from MICINN (Spain

Oil structuring properties of electrospun Kraft lignin/ cellulose acetate nanofibers for lubricating applications: influence of lignin source and lignin/cellulose acetate ratio

In the present work, electrospun Kraft lignin/cellulose acetate nanostructures were produced, assessed and proposed as structuring or thickening agents of castor oil for lubricating applications. Solutions of Kraft lignins (KL) derived from different sources (eucalyptus, poplar and olive tree pruning) and cellulose acetate (CA) were prepared and used as feed for electrospinning. The rheological properties (shear and extensional viscosity), electrical conductivity and surface tension of KL/CA solutions influence the morphology of the electrospun nanofibers, which in turn is affected by the chemical structure and composition of the Kraft lignins. Electrospun KL/CA nanostructures consisting of filament-interconnected nanoparticles, beaded nanofibers or uniform nanofiber mats were able to form gel-like homogeneous fine dispersions by simply mechanically dispersing them into castor oil. The swelling of KL/ CA nanofibers in the percolation network was demonstrated. The rheological, tribological and microstructural properties of these oleogels are essentially governed by the morphological characteristics of the electrospun nanostructures, i.e. fiber diameter, number of beads and porosity. Rheological properties of the resulting oleogels may be tailored by modifying the lignin source and KL:CA weight ratio. According to their rheological and tribological properties, KL/ CA electrospun nanostructures-based oleogels can be proposed as a sustainable alternative to conventional lubricating greases.This work is part of a research project (RTI2018-096080-B-C21) funded by MCIN/AEI/10. 13039/501100011033 and by “ERDF A way of making Europe”. J.F. Rubio-Valle has also received a Ph.D. Research Grant PRE2019-090632 from Ministerio de Ciencia e Innovación (Spain). The financial support is gratefully acknowledged. Universidad de Huelva/CBUA thanks to the CRUE-CSIC agreement with Springer Nature

Production of lignin/cellulose acetate fiber-bead structures by electrospinning and exploration of their potential as green structuring agents for vegetable lubricating oils

In this work we developed electrospun lignin/cellulose acetate fiber-bead nanostructures and explored their potential as structuring agents for vegetable oils to be used as eco-friendly lubricating oleogels. A variety of nanostructures were obtained from solutions containing 20 or 30 wt. % eucalyptus Kraft lignin (EKL) and cellulose acetate (CA) in variable weight ratios from 100:0 to 60:40 in an N,N-dimethylformamide/acetone mixture. The EKL/CA solutions were characterized in physicochemical terms from viscosity, surface tension and electrical conductivity measurements. Also, the electrospun nanostructures were characterized morphologically by scanning electron microscopy. Their morphology was found to be strongly dependent on the rheological properties of the biopolymer solution. Electrospun EKL/CA beaded nanofibers and well-developed uniform nanofiber mats allowed oleogels to be easily obtained by simply dispersing them in castor oil whilst nanoparticle clusters gave rise to unstable dispersions. The rheological properties of these gel-like dispersions can be tailored through the membrane concentration and/or EKL/CA ratio and depend to a large extent on the morphology of the electrospun nanostructures. The rheological and tribological properties of the oleogels were comparable to those previously reported for conventional and other bio-based lubricating greases. Overall, electrospun EKL/CA nanofibers allow easy, efficient structuring of vegetable oils to obtain oleogels holding potential for use as lubricants.Research Project RTI2018–096080-B-C21, funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”. PhD Research Grant PRE2019–090632 from Spain’s Ministry of Science and Innovation. Funding for open access charge: Universidad de Huelva / CBU

Three-year follow-up of posterior chamber phakic intraocular lens with a central port design after deep anterior lamellar keratoplasty

Background: To evaluate clinical outcomes of the Visian implantable collamer lens (ICL) with a central port to correct myopia and astigmatism after deep anterior lamellar keratoplasty (DALK) for keratoconus throughout 3 years of follow-up. Methods: This study included 20 eyes of 20 patients that underwent V4c ICL (13 eyes with a spherical ICL and 7 eyes with a toric ICL) implantation after DALK. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, intraocular pressure (IOP), endothelial cell density (ECD), and vault were analyzed. Results: The mean UDVA improved from the preoperative 1.18 ± 0.33 logMAR to 0.25 ± 0.14 logMAR at 6 months after surgery (P < 0.0001) and remained unchanged throughout the whole follow-up (P = 0.4). All eyes gained lines of CDVA compared to preoperative values. At the last follow-up visit, all eyes achieved CDVA of 0.2 logMAR or better and 13 eyes (65%) 0.1 logMAR or better. At 6 months post-surgery, all eyes (100%) had a spherical equivalent within ± 1.50 D, and 19 (95%) within ± 1.00 D. The mean manifest spherical equivalent was stable over the postoperative follow-up (P = 0.25). No significant increase in IOP occurred in any case throughout the 3 years of follow-up. The loss in ECD from the preoperative baseline at the last follow-up visit was 2.27%. Conclusions: The clinical outcomes suggest that the V4c ICL implantation for correction of myopia and regular astigmatism in post-DALK eyes was satisfactory in terms of effectiveness, safety, and stability during 3 years of follow-up.Depto. de Optometría y VisiónFac. de Óptica y OptometríaTRUESTAAR® Surgical (Estados Unidos)pu

Estudio de calidad de vida de pacientes con coxartrosis

La artroplastia de cadera secundaria a artrosis es una de las intervenciones más frecuentes dentro de la cirugía ortopédica. La coxartrosis produce una limitación funcional severa, que invalida a los pacientes y los hace dependientes para sus actividades cotidianas. Se calcula la calidad de vida aportada en las intervenciones de reemplazo articular de cadera de 85 pacientes con coxartrosis utilizando el “EQ-5D”. La puntuación media preoperatoria fue 0,222 ± 0,320 y la postoperatoria 0,794 ± 0,251. El incremento de calidad de vida en función de la edad de los pacientes siguió una tendencia descendente (β= −0,010), sin diferencias significativas (p=0,214). El incremento de calidad de vida no se vió condicionado por la presencia de infección (p>0,5), duración de la intervención (p>0,5) ni tiempo de estancia hospitalaria (p>0,5). La sustitución de esta articulación ha transformado la vida de muchos de los pacientes incrementando su calidad de vida, principalmente en pacientes que ingresan por coxartrosis en comparación con otros diagnósticos.Hip replacement secondary to osteoarthritis is one of the most performed surgeries in orthopaedic surgery. Osteoarthritis produces a severe functional limitation that invalidates patients and makes them dependent for their daily activities. It is calculated the quality of life provided by hip replacement procedure in 85 osteoarthritis patients using the “EQ-5D”. The mean preoperative score was 0.222 ± 0.320 and the postoperative score 0.794 ± 0.251. The increase in quality of life according to patients age followed a descendent tendency (β= −0.010), without a statitically relationship (p=0.214). The increase in quality of life was not conditioned by infection (p>0.5), length of stay (p>0.5) or length of the procedure (p>0.5). Joint replacement has changed the lives of many patients, increasing their quality of life, mainly in osteoarthritis patients compared to patients with other diagnosis