Distinct magnetic signatures of fractional vortex configurations in multiband superconductors

Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, we examine such vortex configurations in a two-band superconducting slab in parallel magnetic field. The fractional vortices appear due to the band-selective vortex penetration caused by different thresholds for vortex entry within each band-condensate, and stabilize near the edges of the sample. We show that the resulting fractional vortex configurations leave distinct fingerprints in the static measurements of the magnetization, as well as in ac dynamic measurements of the magnetic susceptibility, both of which can be readily used for the detection of these fascinating vortex states in several existing multiband superconductors.Comment: 5 pages, 4 figure

Generalizing the DGLAP Evolution of Fragmentation Functions to the Smallest x Values

An approach which unifies the Double Logarithmic Approximation at small x and the leading order DGLAP evolution of fragmentation functions at large x is presented. This approach reproduces exactly the Modified Leading Logarithm Approximation, but is more complete due to the degrees of freedom given to the quark sector and the inclusion of the fixed order terms. We find that data from the largest x values to the peak region can be better fitted than with other approaches.Comment: 10 pages, 3 figure

Método para avaliar a uniformidade nas fases de cria e recria em lotes de frangas para produção de ovos.

bitstream/item/59417/1/CUsersPiazzonDocuments34.pdfProjeto n. 01.02.10.406-0

Size also matters in biodegradable composite microfiber reinforced by chitosan nanofibers

Pioneer works on nanocomposites were focused in carbon nanofibers or nanotubes dispersed in epoxy matrix, a viscous liquid facilitating the compounding stage. The interest in developing new composites aimed for biomedical applications led us to design new nanocomposites based in biodegradable polymers with demonstrated biological performance. We report herein the development of micro-nano composites by extruding poly(butylene succinate) (PBS) microfibers with two different diameters, 200 and 500 m, reinforced with electrospun chitosan nanofibers. Analysis of the microfibers showed high levels of alignment of the reinforcing phase and excellent distribution of the nanofibers in the composite. Its geometry facilitates the development of orthotropy, maximizing the reinforcement in the axial fiber main axis. The biodegradable microfiber composites show an outstanding improvement of mechanical properties and of the kinetics of biodegradation, with very small fractions (0.05 and 0.1 wt.%) of electrospun chitosan nanofibers reinforcement. The high surface area-to-volume ratio of electrospun nanofibers combined with the increased water uptake capability of chitosan justify the accelerated kinetics of biodegradation of the composite as compared with the unfilled synthetic polymer.FCT -Fundação para a Ciência e a Tecnologi

Aproveitamento da água da chuva na produção de suínos e aves.

bitstream/item/79687/1/Doc-157.pdfProjeto/Plano de Ação: 01.10.06.001

Avaliação química e biológica de ingredientes nacionais utilizados em rações de suínos.

bitstream/item/59172/1/CUsersPiazzonDocuments44.pd

Surface controlled biomimetic coating of polycaprolactone nanofiber meshes to be used as bone extracellular matrix analogues

The aim of this work was to develop novel electrospun nanofiber meshes coated with a biomimetic calcium phosphate (BCP) layer that mimics the extracellular microenvironment found in the human bone structure. Poly(!-caprolactone) (PCL) was selected because of its well-known medical applications, its biodegradability, biocompatibility and its susceptibility to partial hydrolysis by a straightforward alkaline treatment. The deposition of a calcium phosphate layer, similar to the inorganic phase of bone, on PCL nanofiber meshes was achieved by means of a surface modification. This initial surface modification was followed by treatment with solutions containing calcium and phosphate ions. The process was finished by a posterior immersion in a simulated body fluid (SBF) with nearly 1.5× the inorganic concentration of the human blood plasma ions. After some optimization work, the best conditions were chosen to perform the biological assays. The influence of the bone-like BCP layer on the viability and adhesion, as well as on the proliferation of human osteoblast-like cells, was assessed. It was shown that PCL nanofiber meshes coated with a BCP layer support and enhance the proliferation of osteoblasts for long culture periods. The attractive properties of the coated structures produced in the present work demonstrated that those materials have potential to be used for applications in bone tissue engineering. This is the first time that nanofiber meshes could be coated with a biomimetic bone-like calcium phosphate layer produced in a way that the original mesh architecture can be fully maintained.This work was partially supported by the EU Integrated Project GENOSTEM (Adult Mesenchymal Stem Cells Engineering for connective tissue disorders: from the bench to the bed side, No. LSH503161) and by the project Naturally Nano (POCI/EME/58982/2004), financed by the Portuguese Foundation for Science and Technology (FCT). A. M. would like to thank FCT for his PhD grant (SFRH/BD/24382/2005). I. B. L. also thanks FCT for a PhD scholarship (SFRH/BD/9031/2002). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)

Evaluation of extracellular matrix formation in polycaprolactone and starch-compounded polycaprolactone nanofiber meshes when seeded with bovine articular chondrocytes

Cartilage defects are a major health problem. Tissue engineering has developed different strategies and several biomaterial morphologies, including natural-based ones, for repairing these defects. We used electrospun polycaprolactone (PCL) and starch-compounded PCL (SPCL) nanofiber meshes to evaluate extracellular matrix (ECM) formation by bovine articular chondrocytes (BACs). The main aim of this work was to evaluate the suitability of PCL and SPCL nanofiber meshes in chondrocyte cultures, and their capability to produce ECM when seeded onto these nanostructured materials. The effect of culture conditions (static vs dynamic) on ECM formation was also assessed. BACs were seeded onto PCL and SPCL nanofiber meshes using a dynamic cellseeding procedure and cultured under static or dynamic conditions for 4 weeks. Constructs were characterized using scanning electron microscopy, histology, immunolocalization of collagen types I and II, and glycosaminoglycan (GAG) quantification. Results show an extensive cell colonization of the entire nanofiber mesh, for both materials, and that chondrocytes presented typical spherical morphology. Some degree of cell infiltration inside the nanofiber meshes was noticeable for both materials. ECM formation and GAG were detected throughout the materials, evidencing typical construct maturation. PCL and SPCL nanofiber meshes are suitable as supports for ECM formation and therefore are adequate for cartilage tissue-engineering approaches.M. Alves da Silva would like to acknowledge the Portuguese Foundation for Science and Technology (FCT) for her grant (SFRH/BD/28708/2006), Marie Curie Actions-ALEA JACTA EST (MEST-CT-2004-008104), European NoE EXPERTISSUES (NMP3-CT-2004-500283), IP GENOSTEM (LSHB-CT-2003-503161) and NATURALLY NANO (POCTI/EME/58982/2004)