1,721,036 research outputs found
A novel concept of steerable catheters actuated by muscle cells: the BioMeld project
No full textLocalized (targeted) therapies allow increasing the efficacy of treatments for several diseases, including cancer. Within this view, the BioMeld project aims at proposing a pipeline to guide the fabrication of an innovative intravascular steerable microcatheter, actuated on its tip by muscle cell contraction. A simulation framework streamlines the process of design quoting, manufacturing, verification, and reporting, thus significantly reducing error-prone manual steps and making the process more efficient. This new generation of steerable microcatheter, fostered by the unconventional kind of actuation provided by muscle cells, will be investigated throughout this project to target localized treatments of deeper and tortuous regions within the cardiovascular systems. In this work we report the overall project vision and we describe some preliminary results on the microcatheter design
Fabrication, characterization, and properties of poly (ethylene-co-vinyl acetate) composite thin films doped with piezoelectric nanofillers
No full textEthylene vinyl acetate (EVA) is a copolymer comprehending the semi-crystalline polyethylene and amorphous vinyl acetate phases, which potentially allow the fabrication of tunable materials. This paper aims at describing the fabrication and characterization of nanocomposite thin films made of polyethylene vinyl acetate, at different polymer concentration and vinyl acetate content, doped with piezoelectric nanomaterials, namely zinc oxide and barium titanate. These membranes are prepared by solvent casting, achieving a thickness in the order of 100-200 mu m. The nanocomposites are characterized in terms of morphological, mechanical, and chemical properties. Analysis of the nanocomposites shows the nanofillers to be homogeneously dispersed in EVA matrix at different vinyl acetate content. Their influence is also noted in the mechanical behavior of thin films, which elastic modulus ranged from about 2 to 25 MPa, while keeping an elongation break from 600% to 1500% and tensile strength from 2 up to 13 MPa. At the same time, doped nanocomposite materials increase their crystallinity degree than the bare ones. The radiopacity provided by the addition of the dopant agents is proven. Finally, the direct piezoelectricity of nanocomposites membranes is demonstrated, showing higher voltage outputs (up to 2.5 V) for stiffer doped matrices. These results show the potentialities provided by the addition of piezoelectric nanomaterials towards mechanical reinforcement of EVA-based matrices while introducing radiopaque properties and responsiveness to mechanical stimuli
Novel Ultrathin Films Based on a Blend of PEG- b-PCL and PLLA and Doped with ZnO Nanoparticles
No full textIn this paper, a novel nanofilm type is proposed based on a blend of poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-b-PCL) and poly(l-lactic acid), doped with zinc oxide nanoparticles (ZnO NPs) at different concentrations (0.1, 1, and 10 mg/mL). All nanofilm types were featured by a thickness value of ∼500 nm. Increasing ZnO NP concentrations implied larger roughness values (∼22 nm for the bare nanofilm and ∼67 nm for the films with 10 mg/mL of NPs), larger piezoelectricity (average d33 coefficient for the film up to ∼1.98 pm/V), and elastic modulus: the nanofilms doped with 1 and 10 mg/mL of NPs were much stiffer than the nondoped controls and nanofilms doped with 0.1 mg/mL of NPs. The ZnO NP content was also directly proportional to the material melting point and crystallinity and inversely proportional to the material degradation rate, thus highlighting the stabilization role of ZnO particles. In vitro tests were carried out with cells of the musculoskeletal apparatus (fibroblasts, osteoblasts, chondrocytes, and myoblasts). All cell types showed good adhesion and viability on all substrate formulations. Interestingly, a higher content of ZnO NPs in the matrix demonstrated higher bioactivity, boosting the metabolic activity of fibroblasts, myoblasts, and chondrocytes and enhancing the osteogenic and myogenic differentiation. These findings demonstrated the potential of these nanocomposite matrices for regenerative medicine applications, such as tissue engineering
Gellan gum-based hydrogels as injectable materials for cartilage tissue engineering
No full textRecently, new tissue engineering approaches are being developed as an alternative to traditional treatments for cartilage repair. Materials in the form of hydrogels are particularly attractive as owing to their biocompatibility, degradability, and ability to homogeneously mix with stem cells and bioactive molecules. Hydrogels can be injectable, thus to easily fill defects with different shapes, thus repairing the articular cartilage in a minimally invasive way. This manuscript reports the analysis of gellan gum-based hydrogels as injectable materials for the in situ delivery of chondrocytes for the treatment of cartilage defects. Gellan gum and methacrylated gellan gum were prepared and analyzed through rheometry, to assess their suitability for being injected with chondrocytes. Then, one selected formulation was further characterized in terms of mechanical properties, analyzing the influence of light exposure. Finally, preliminary biological tests with chondrocytes were performed to analyze the interaction with the material
Injectable gelatin-based photocurable fiber-reinforced hydrogel for the treatment of osteochondral defects
No full textOsteochondral defects are one of the most motor-disabling conditions worldwide. A limited intrinsic regenerative capability features cartilage and bone tissues involved in large osteochondral lesions and, to date, there is no clinical treatment capable of appropriately restoring them. We report an innovative injectable composite hydrogel based on gelatin methacryloyl (GelMA) loaded with dispersed fibers made of a blend polycaprolactone (PCL)/GelMA. The fibers were produced by electrospinning, and cut in stripes using a cryostat-based cutting approach. Their embodiment in the GelMA matrix improved the compressive mechanical properties of the pristine GelMA hydrogel. Specific conditions (needle size: 18G and 20G; temperature: 30 and 37°C) were found compatible with the injection of the composite hydrogel, before crosslinking, matching the criteria reported in EN ISO 7886 1:2018 standard. These preliminary results are promising in view of the optimization of injectable reinforced GelMA-based formulations to be used for the treatment of osteochondral injuries
Injectable gelatin-based photocurable fiber-reinforced hydrogel for the treatment of osteochondral defects
No full textOsteochondral defects are one of the most motor-disabling conditions worldwide. A limited intrinsic regenerative capability features cartilage and bone tissues involved in large osteochondral lesions and, to date, there is no clinical treatment capable of appropriately restoring them. We report an innovative injectable composite hydrogel based on gelatin methacryloyl (GelMA) loaded with dispersed fibers made of a blend polycaprolactone (PCL)/GelMA. The fibers were produced by electrospinning, and cut in stripes using a cryostat-based cutting approach. Their embodiment in the GelMA matrix improved the compressive mechanical properties of the pristine GelMA hydrogel. Specific conditions (needle size: 18G and 20G; temperature: 30 and 37°C) were found compatible with the injection of the composite hydrogel, before crosslinking, matching the criteria reported in EN ISO 7886 1:2018 standard. These preliminary results are promising in view of the optimization of injectable reinforced GelMA-based formulations to be used for the treatment of osteochondral injuries
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Novel Steerable Catheter Controlled with a Biohybrid Actuator: A Feasibility Study
Full text linkTargeted therapies allow increasing the efficacy of treatments for several diseases, including cancer. The release of drugs or chemicals directly in the site of interest will be beneficial for maximizing the therapy and minimize side effects. Here, we report the concept and a preliminary analysis of an innovative intravascular steerable catheter guided by an on-board biohybrid actuator, aiming to release drugs into deep and tortuous regions within the cardiovascular systems. The catheter performance has been estimated through analytical and numerical analyses, varying catheter diameter, wall thickness, and actuator force. Results show how larger catheter deflections can be obtained with a smaller outer diameter and decreasing wall thickness. Besides, improved outcomes can be achieved by applying the biohybrid actuator distant from the catheter tip extremity and maximizing the magnitude of the applied forces. Despite the need to further improve the performance of this concept (e.g., by decreasing material stiffness), these preliminary results show great promise in view of future experimentation of such kind of actuation to drive microcatheters through the cardiovascular network
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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