Search results for "Maqui"

Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bi…

2019

[EN] Dielectric Thermal Analysis (DETA) of a series of new thermoset obtained by click chemistry was performed. The new thermosets were obtained by a dual-curing process consisting in a first photochemical thiol-ene, followed by a thermal thiol-epoxy starting from an allyl-terminated hyperbranched poly(ethyleneimine) (HBPEI) and different proportions of diglycidylether of bisphenol A (DGEBA) and the corresponding stoichiometric proportions of pentaerythritol tetrakis (3-mercaptopropionate, PETMP). The dielectric behaviour was obtained experimentally supressing the conductive effects. Two sub-Tg intramolecular non-cooperative gamma and beta relaxations and an intermolecular cooperative alpha…

Hyaluronic Acid–Silica Nanohybrid Gels

2013

Excessive water sorption and low mechanical properties are a severe drawback in some biomedical applications of hyaluronic acid (HA). A way to improve these properties is here explored through the novel concept of nanohybrid hydrogels consisting of a HA matrix including different amounts of silica-derived species. This inorganic filler phase controls the mechanical and swelling properties of HA cross-linked matrices. Below a 2 wt % of silica in the systems, nanoparticle aggregates of tens of nanometers and silica oligomers are distributed more or less homogeneously throughout the organic matrix, without percolating. This morphology of the silica phase is accompanied by an increased swelling…

Biostable Scaffolds of Polyacrylate Polymers Implanted in the Articular Cartilage Induce Hyaline-Like Cartilage Regeneration in Rabbits

2017

[EN] Purpose: To study the influence of scaffold properties on the organization of ¿in vivo¿ cartilage regeneration. Our hypothesis is that stress transmission to the cells seeded inside the scaffold pores or surrounding it, which is highly dependent on the scaffold properties, determine differentiation of both mesenchymal cells and dedifferentiated autologous chondrocytes. Methods: Four series of porous scaffolds made of different polyacrylate polymers, previously seeded with cultured rabbit chondrocytes or without cells preseeded, were implanted in cartilage defects in rabbits. Subchondral bone was always injured during the surgery in order to allow blood to reach the implantation site an…

Implantation of a polycaprolactone scaffold with subchondral bone anchoring ameliorates nodules formation and other tissue alterations

2015

Purpose: Articular cartilage has limited repair capacity. Two different implant devices for articular cartilage regeneration were tested in vivo in a sheep model to evaluate the effect of subchondral bone anchoring for tissue repair. Methods: The implants were placed with press-fit technique in a cartilage defect after microfracture surgery in the femoral condyle of the knee joint of the sheep and histologic and mechanical evaluation was done 4.5 months later. The first group consisted of a biodegradable polycaprolactone (PCL) scaffold with double porosity. The second test group consisted of a PCL scaffold attached to a poly(L-lactic acid) (PLLA) pin anchored to the subchondral bone. Result…

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2022

Tributo al professor Miguel F. Refojo, PhD, DSc (1928---2016)

2016

[Excerpt] July 21, 2016, Professor Miguel F. Refojo passed away at the age of 88 in Needham (Massachusetts). Saying that Miguel was one of the most renowned Spanish scientists of the second half of the XXth Century does not resembles its actual scientific size. Indeed, Miguel (or “Migüel” as most of his American friends pronounced his name) was a World Class scientist and inventor that will be forever linked to the advances in polymer science applied to the ophthalmic environment. His contributions in the biomedical field start “officially” in 1967 according to the National Library of Medline database (Pubmed-Medline). [...]

Thermal analysis applied to the characterization of degradation in soil of polylactide: I. Calorimetric and viscoelastic analyses

2010

[EN] An accelerated soil burial test has been performed on a commercial polylactide (PLA) for simulating non-controlled disposal. Degradation in soil promotes physical and chemical changes in polylactide properties, which can be characterized by Thermal Analysis techniques. Physical changes occurred in polylactide due to the degradation in soil were evaluated by correlating their calorimetric and visco-elastic properties. It is highly remarkable that each calorimetric scan offers specific and enlightening information. Degradation in soil affects the polylactide chains reorganization. A multimodal melting behavior is observed for buried PLA, degradation in soil also promotes the enlarging th…

Effect of sisal and hydrothermal ageing on the dielectric behaviour of polylactide/sisal biocomposites

2017

[EN] The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from - 130 degrees C to 130 degrees C) and frequency ranges (from 10(-2)-10(7) Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulc…

Subsurface flow and large-scale lateral saturated soil hydraulic conductivity in a Mediterranean hillslope with contrasting land uses

2017

Abstract The lateral saturated hydraulic conductivity, Ks,l , is the soil property that mostly governs subsurface flow in hillslopes. Determinations of Ks,l at the hillslope scale are expected to yield valuable information for interpreting and modeling hydrological processes since soil heterogeneities are functionally averaged in this case. However, these data are rare since the experiments are quite difficult and costly. In this investigation, that was carried out in Sardinia (Italy), large-scale determinations of Ks,l were done in two adjacent hillslopes covered by a Mediterranean maquis and grass, respectively, with the following objectives: i) to evaluate the effect of land use change o…

Use of poly(amidoamine) drug conjugates for the delivery of antimalarials to Plasmodium

2013

Current malaria therapeutics demands strategies able to selectively deliver drugs to Plasmodium-infected red blood cells (pRBCs) in order to limit the appearance of parasite resistance. Here, the poly(amidoamines) AGMA1 and ISA23 have been explored for the delivery of antimalarial drugs to pRBCs. AGMA1 has antimalarial activity per se as shown by its inhibition of the in vitro growth of Plasmodium falciparum, with an IC50 of 13.7 μM. Fluorescence-assisted cell sorting data and confocal fluorescence microscopy and transmission electron microscopy images indicate that both polymers exhibit preferential binding to and internalization into pRBCs versus RBCs, and subcellular targeting to the par…