1,721,037 research outputs found
Embedded 3D printing for the development of perfusable in vitro 3D model of soft tissue
Full text linkHydrogels are widely investigated to develop 3D in vitro models for mimicking tissue microenvironment since their properties well match soft tissues ones. One concern is the lack of an adequate channel network, mimicking the tissue vascularization. Optimizing a vascularization strategy still remains challenging. We optimized and characterized a GelMA/Pluronic combination by using embedded 3D printing for the realization of a channel network in a GelMA scaffold
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
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
Evaluation of the subtle trade-off between physical stability and thermo-responsiveness in crosslinked methylcellulose hydrogels
No full textMethylcellulose (MC) hydrogels, undergoing sol-gel reversible transition upon temperature changes, lend themselves to smart system applications. However, their reduced stability in aqueous environment and unsatisfactory mechanical properties limit the breadth of their possible applications. Here, a crosslinking strategy based on citric acid (CA) was developed: exploiting three crosslinking parameters (CA concentration, crosslinking time, and crosslinking temperature) by a design of experiment approach, optimized crosslinked MC hydrogels (MC-L, MC-M, MC-H) were obtained and characterized. Swelling tests in water revealed the effectiveness of CA crosslinking in modulating the water uptake of MC hydrogels. Both theoretical and experimental analyses showed an increase in the crosslinking density by the rationale selection of process parameters. The extent of sol-gel transition was assessed by swelling tests, Raman spectroscopy and rheological analyses. MC-M samples demonstrated to preserve their thermo-responsive behavior around their lower critical solution temperature (LCST), while showing increased stability and enhanced mechanical properties when compared to pristine MC hydrogels. This journal i
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
3D printing of methylcellulose-based hydrogels
No full textMethylcellulose-based (MC) hydrogels are optimal substrates to obtain cell sheets for regenerative medicine applications. However, current MC-based hydrogel preparation methods only allow for the obtainment of MC substrates with standardized and simple geometries (i.e., geometry of the container where the hydrogel is produced). Here, we propose the 3D printing of a MC-based hydrogel to obtain substrates with desired and controlled geometries. First, we optimize the printing temperature (i.e., T = 21 °C) of the MC-based hydrogel, so to obtain printed strands reproducing the designed geometry without defects. We investigate the influence of the printing parameters (i.e., needle size, deposition speed and extrusion multiplier) on the printed strands diameters and printing accuracy. A decrease in the sol-gel transition temperature was evidenced, together with an increase in water uptake at 37 °C, for printed MC-based hydrogels compared to not printed samples; the stability at 37 °C and achieved rheological properties were suitable for cell sheet engineering applications. In addition, cell viability higher than 90% was detected after embedding cells in the MC-based hydrogel; moreover, the optimized printing parameters allowed to bioprint C2C12 cells embedded in the MC-based hydrogel with a viability higher than 80%. The printing parameters we optimized could be used to produce MC substrates for cell sheet engineering or cell delivery applications with controlled and complex-shaped geometries
Plant Tissues as 3D Natural Scaffolds for Adipose, Bone and Tendon Tissue Regeneration
Full text linkDecellularized tissues are a valid alternative as tissue engineering scaffolds, thanks to the three-dimensional structure that mimics native tissues to be regenerated and the biomimetic microenvironment for cells and tissues growth. Despite decellularized animal tissues have long been used, plant tissue decellularized scaffolds might overcome availability issues, high costs and ethical concerns related to the use of animal sources. The wide range of features covered by different plants offers a unique opportunity for the development of tissue-specific scaffolds, depending on the morphological, physical and mechanical peculiarities of each plant. Herein, three different plant tissues (i.e., apple, carrot, and celery) were decellularized and, according to their peculiar properties (i.e., porosity, mechanical properties), addressed to regeneration of adipose tissue, bone tissue and tendons, respectively. Decellularized apple, carrot and celery maintained their porous structure, with pores ranging from 70 to 420 μm, depending on the plant source, and were stable in PBS at 37°C up to 7 weeks. Different mechanical properties (i.e., Eapple = 4 kPa, Ecarrot = 43 kPa, Ecelery = 590 kPa) were measured and no indirect cytotoxic effects were demonstrated in vitro after plants decellularization. After coating with poly-L-lysine, apples supported 3T3-L1 preadipocytes adhesion, proliferation and adipogenic differentiation; carrots supported MC3T3-E1 pre-osteoblasts adhesion, proliferation and osteogenic differentiation; celery supported L929 cells adhesion, proliferation and guided anisotropic cells orientation. The versatile features of decellularized plant tissues and their potential for the regeneration of different tissues are proved in this work
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