117,781 research outputs found
S+C+L Double Pass EDF Amplifier, Amplified Spontaneous Emission Source and Multiwavelength Ring Laser
No full textIn- and Out-Coupling of Light in Photonic-Crystal and Conventional Dielectric Waveguides of Arbitrary Width
No full textA new approach for light coupling between wire dielectric and photonic crystal waveguides, is investigated to optimize the transmission spectrum around 1550 nm. The approach is successfully proposed for input and output coupling with waveguides of arbitrary width, even much larger than the single line defect photonic crystal waveguide. It is shown that the displacement across the interface of the inner hole rows of the photonic crystal waveguide considerably enhances the coupling, resulting in transmission values higher than 90% over bandwidths of hundreds of nanometers. © 2005 IEEE
Effect of ethanol treatment on Poly(L)lactic acid electrospun fibre morphology
No full textElectrospun (ES) materials are considered highly promising scaffolds for tissue engineering given their particular fibrous morphology that resembles the fibrous component of tissue extracellular matrix. ES scaffolds made of commercial bioresorbable polyesters can be dramatically affected by commonly employed sterilization methods (e.g. autoclaving, ethylene oxide, -rays), thus they are usually disinfected with ethanol (EtOH) before being used in contact with a biological environment. However, even if less extensively, also EtOH disinfection might affect ES scaffold morphology and, consequently, the response of cells cultured onto them.
This work aims at investigating the effect of EtOH sterilization on poly(L)lactic acid (PLLA) ES scaffold and in particular on its phase morphology (amorphous to crystalline ratio). The morphological changes of PLLA non-woven mats treated at different temperatures by using EtOH solutions with different concentration, were compared. Moreover, the behaviour of H9c2 cardiac cells seeded onto PLLA scaffolds treated with EtOH was investigated
Cut-off properties of large-mode-area photonic crystal fibers
No full textThe cutoff properties of triangular photonic crystal fibers with different core dimensions have been deeply investigated. In particular, 7-rod core fibers, obtained by removing the air-holes belonging to the first ring, as well as the central one in the fiber cross-section, have been considered. A phase diagram which describes the regions of single-mode and multi-mode operation for these large mode area fibers has been calculated with two different approaches. Simulation results have demonstrated that, for a fixed air-filling fraction, triangular photonic crystal fibers with a wider silica core region are single-mode in a smaller wavelength range. As a consequence, also the endlessly single-mode region of 7-rod core triangular fibers is smaller than that of 1-rod core ones. However, by properly choosing low air-filling fraction and relatively small hole-to-hole distance, 7-rod core photonic crystal fibers can provide high effective area values, as well as single-mode operation, without the problem of leakage losses
Ethanol disinfection affects physical properties and cell response of electrospun poly(l-lactic acid) scaffolds
No full textDisinfection of electrospun materials is commonly carried out by ethanol (EtOH) soaking. However, in the literature no systematic investigation on the effect of EtOH disinfection on scaffold properties is available. In this study electrospun poly(L-lactic acid) (PLLA) scaffolds were differently treated in EtOH and changes of fiber morphology, fiber surface topography and scaffold thermo-mechanical properties were evaluated. It was found that EtOH induced the formation of an amount of crystal phase, in the initially amorphous fibers, which depends on EtOH grade, soaking time and temperature. Completely amorphous PLLA (a-PLLA) and semicrystalline PLIA (sc-PLLA) scaffolds were produced by applying different EtOH treatments to as-spun PLLA scaffold. Compared to a-PLLA, sc-PLLA was stiffer and composed of fibers with rougher surface. Cell culture performed by using permanent cell line H9c2 demonstrated that changes of scaffold properties determined a different cell response, in particular in the expression of proteins correlated to cell motility and cell adhesion
Superficial acral fibromyxoma: immunohistochemical and ultrastructural analysis of a case, with literature review.
No full textSuperficial acral fibromyxoma (SAFM) is an uncommon tumor of the superficial soft tissues of acral sites. SAFM is a proliferation of fibroblastic cells, within a myxoid to collagenous stroma. The published cases mostly expressed immunoreactivity for CD34, CD99, EMA, and, less frequently, CD10. The authors report an additional case that did not express any of the previously reported markers, including CD34, and antigens of mesenchymal stromal lineage. Ultrastructural study confirmed the tumor cells were typical fibroblasts with cytoplasmic intermediate filaments and numerous cisternae of rough endoplasmic reticulum. The authors describe the first example of SAFM, ultrastructurally studied, with pure fibroblastic immunoprofile
Paraffin embedding allows effective analysis of proliferation, survival, and immunophenotyping of cells cultured on poly(l-lactic acid) electrospun nanofiber scaffolds.
No full textMorphological and immunophenotypic characterization of cells grown on poly(l-lactic acid) (PLLA) electrospun scaffolds is usually performed using immunofluorescence and cryosections. However, these methods present practical limits; histological processing, on the other hand, is believed to lead to artifactual changes in the scaffold structure. Here the formalin-fixed paraffin-embedding (FFPE) procedure was tailored to process PLLA electrospun scaffolds grown with human umbilical vein endothelial cells. After 1 to 7 days of culture, the scaffolds were processed with the FFPE procedure. Using this protocol, not only cross sections but also "en face" sections were obtained. This made possible to perform the effective light microscopy analysis of cell morphology and to assess cell adhesion and penetration without considerable scaffold damage. The method was also suitable for immunohistochemical assays, such as proliferation (Ki67), extracellular matrix production (type IV collagen), survival (cleaved caspase-3), and immunophenotyping (KDR, CD44, vimentin, CD45); results were compared with those obtained using complementary techniques (scanning electron microscopy, Alamar Blue assay, and cryosections). The FFPE protocol can be safely applied to PLLA scaffolds and provides information that are essential to study the mechanisms of interaction between cells and PLLA fibers before their potential implantation in vivo
Are low frequency macroeconomic variables important for high frequency electricity prices?
No full textRecent research finds that forecasting electricity prices is very relevant. In many applications, it might be interesting to predict daily electricity prices by using their own lags or renewable energy sources. However, the recent turmoil of energy prices and the Russian-Ukrainian war increased attention in evaluating the relevance of industrial production and the Purchasing Managers' Index output survey in forecasting the daily electricity prices. We develop a Bayesian reverse unrestricted MIDAS model which accounts for the mismatch in frequency between the daily prices and the monthly macro variables in Germany and Italy. We find that the inclusion of macroeconomic low frequency variables is more important for short than medium term horizons by means of point and density measures. In particular, accuracy increases by combining hard and soft information, while using only surveys gives less accurate forecasts than using only industrial production data
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