La filatura neumàtica és la tecnologia de filatura amb més projecció de futur gràcies a la seva elevada productivitat i qualitat del fil produït; no obstant, la seva introducció en el mercat és lenta a nivell mundial. A pesar de què pot assolir una productivitat molt elevada en front als sistemes convencionals, encara té altres limitacions que impedeixen el seu èxit. El present treball de tesi s¿ha centrat en el estudi de les corrents neumàtiques dins la tovera de filatura, dispositiu clau de la tecnologia de filatura neumàtica; el flux d¿aire dins la tovera condueix les fibres per tal de formar el fil; el coneixement generat s¿ha emprat per estudiar el comportament de la tovera sota diferents condicions productives i finalment desenvolupar i analitzar dissenys alternatius fins que un nou disseny satisfactori ha estat assolit.Sota el punt de vista de rendiment del sistema, els objectius claus fixats han estat la millora de la regularitat i tenacitat del fil, la reducció del desaprofitament de matèria i la optimització de la eficiència energètica de la tovera.
The feasibility of using Phosphate Buffer Saline (PBS)/ethanol mixtures as a benign solvent to electrospin three types of gelatin was studied. Gelatins with different chemical properties, such as Bloom, were selected and the effect of the gelatin nature and its concentration on the electrospinnability of the dope solution and on the fiber diameter of the electrospun mats were studied. Viscosity of the gelatin solution, which follows a power law relationship with the gelatin concentration, was found to significantly influence the morphology of the mats and the fiber diameter. It was demonstrated that the PBS/ethanol solvent interacted with the gelatins as a good solvent with a Flory exponent of 0.65. In addition, the effect of the solvent composition on the fiber formation process was evaluated corroborating that the ionic strength of the medium and the PBS/ethanol ratio significantly affected the morphology and the diameter of the electrospun fibers. Chemical structure and thermal stability of the electrospun gelatin mats were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). Finally, cytotoxicity of the electrospun mats was analyzed by the Alamar Blue assay, using human foreskin fibroblasts (BJ-5ta), resulting in a high cell viability (80-90%) regardless the type of gelatin
Monterrubio, C.; Pascual, G.; Cano, F.; Vilà, M.; Manzanares, A.; Schaiqueviche, P.; Tornero, J.; Sosnik, A.; Mora, J.; Montero, Á. Biomaterials Vol. 79, p. 69-78 DOI: 10.1016/j.biomaterials.2015.11.055 Data de publicació: 2015-12-02 Article en revista
In addition to surgery, local tumor control in pediatric oncology requires new treatments as an alternative to radiotherapy. SN-38 is an anticancer drug with proved activity against several pediatric solid tumors including neuroblastoma, rhabdomyosarcoma and Ewing sarcoma. Taking advantage of the extremely low aqueous solubility of SN-38, we have developed a novel drug delivery system (DDS) consisting of matrices made of poly(lactic acid) electrospun polymer nanofibers loaded with SN-38 microcrystals for local release in difficult-to-treat pediatric solid tumors. To model the clinical scenario, we conducted extensive preclinical experiments to characterize the biodistribution of the released SN-38 using microdialysis sampling in vivo. We observed that the drug achieves high concentrations in the virtual space of the surgical bed and penetrates a maximum distance of 2 mm within the tumor bulk. Subsequently, we developed a model of subtotal tumor resection in clinically relevant pediatric patient-derived xenografts and used such models to provide evidence of the activity of the SN-38 DDS to inhibit tumor regrowth. We propose that this novel DDS could represent a potential future strategy to avoid harmful radiation therapy as a primary tumor control together with surgery
Erencia, M.; Cano, F.; Tornero, J.; Macedo, M.M.; Tzanov, T.; Macanás, J.; Carrillo, F. Journal of applied polymer science Vol. 132, num. 25, p. 42115 (1/11)-42115 (11(11) DOI: 10.1002/app.42115 Data de publicació: 2015-03-13 Article en revista
Gelatin fibers were prepared by electrospinning of gelatin/acetic acid/water ternary mixtures with the aim of studying the feasibility of fabricating gelatin nanofiber mats at room temperature using an alternative benign solvent by significantly reducing the acetic acid concentration. The results showed that gelatin nanofibers can be optimally electrospun with low acetic acid concentration (25% v/v) combined with gelatin concentrations higher than 300 mg/ml. Both gelatin solutions and electrospun gelatin mats (prepared with different acetic acid aqueous solutions) were analyzed by FTIR and DSC techniques in order to determine the chemical and structure changes
of the polymer. The electrospun gelatin mats fabricated from solutions with low acetic acid content showed some advantages as the maintenance of the decomposition temperature of the pure gelatin (~230ºC) and the reduction of the acid content on electrospun mats, which allowed to reach a cell viability upper than 90% (analyzed by
cell viability test using human dermal fibroblast and embryonic kidney cells). This study has also analyzed the influence of gelatin and acetic acid concentration both on the solution viscosity and the electrospun fiber diameter, obtaining a clear relationship between these parameters
El sistema comprende: - unos medios de dispensación que incluyen una aguja (1) por la punta de la cual dispensar, por electrohilado, una substancia en solución (P), - un colector (3) para recibir la substancia dispensada por la aguja (1) una vez solidificada formando unas fibras (Pt), y - unos medios de suministro de disolvente que comprenden un contenedor (2) de disolvente en estado líquido (Ls) dispuesto cerca de la punta de la aguja (1), para suministrar disolvente en estado gaseoso (Gs) al entorno de salida de la misma, incluyendo la zona del cono de Taylor (Ct), mediante la evaporación del disolvente en estado líquido (Ls). El método comprende suministrar disolvente en estado gaseoso (Gs) al entorno de salida de la punta de la aguja (1), mediante la evaporación localizada, en las proximidades de la zona de creación del cono de Taylor (Ct), de un disolvente en estado líquido (Ls).
'A typical problem of Extremal Combinatorics is to maximise or minimise a certain parameter given some combinatorial restrictions. This area experienced a remarkable growth in the last few decades, having a wide range of applications that include results in number theory, algebra, geometry, logic, information theory, and theoretical computer science. There are also many practical fields that were greatly influenced by ideas from Extremal Combinatorics such as, for example, analysis of large networks, ranking of web-pages, or shotgun cloning of DNA fragments.
The Principal Investigator (PI for short) will work on a number of extremal problems, with the main directions being the Tur\'an function (maximising the size of a hypergraph without some fixed forbidden subgraphs), the Rademacher-Tur\'an problem (minimising the density of F-subgraphs given the edge density), and Ramsey numbers (quantitative bounds on the maximum size of a monochromatic substructure that exists for every colouring). These are fundamental and general questions that go back at least as far as the 1940s but remain wide open despite decades of active attempts. During attacks on these notoriously difficult problems, mathematicians developed a number of powerful general methods. PI will work on extending and sharpening these techniques as well as on finding ways of applying the recently introduced concepts of (hyper)graph limits and flag algebras to concrete extremal problems. Since these concepts deal with some approximation to the studied problem, one important aspect of the project is to develop methods for obtaining exact results from asymptotic calculations (for example, via the stability approach).
The support by means of a 5-year research grant will enable PI to consolidate his research and build a group in Extremal Combinatorics.'
Ventura, H.; Ardanuy, M.; Capdevila, F.; Cano, F.; Tornero, J. Journal of the Textile Institute Vol. 105, num. 10, p. 1065-1075 DOI: 10.1080/00405000.2013.874628 Data de publicació: 2014-06-26 Article en revista
The main objective of this paper is to study the effects of the processing parameters of the needle-punching machine and the interactions between them on some physico-mechanical properties of interest of nonwoven (NW) fabrics. For this purpose, a fractional factorial design has been planned with two levels for each factor: feeding speed, delivery speed, stroke frequency, penetration depth and gap between plates. Sixteen NW fabrics were obtained from polyester fibre and characterized by tensile strength and stiffness for mechanical behaviour and air permeability as physical properties of interest in some technical applications. The results have been subjected to statistical analysis in order to find the effects of the processing variables and the interactions between them on the fabric properties. It was possible to find the effects of the five processing parameters studied on the thickness, fabric mass, stiffness, tensile strength and air permeability of the obtained needle-punched fabrics
The development of suitable biomimetic scaffolds is a fundamental requirement of tissue engineering. Although electrospinning has emerged as an effective method for producing such scaffolds of nanometer-sized fibers, the influence of solution characteristics on the morphology of the resulting nanofibers depends on each polymer solution system. In this study, gelatin nanofibers and microfibers were prepared via electrospinning using mixtures of water and acetic acid at different ratios as solvents. The viscosities of gelatin solutions before electrospinning were analyzed and two different behaviors were found as a function of the solvent composition, taking into account classic models of polymer science. A power law relationship between viscosity and gelatin concentration was found for each solvent system, and an empirical model including the influence of acetic acid was obtained for aqueous systems. Moreover, a ternary diagram considering gelatin, water, and acetic acid mass fractions was constructed as a tool to establish the electrospinnability domains in terms of fiber occurrence and morphology. Also, the isodiametric curves were defined in the fibers region. Finally, in order to correlate the diameter of electrospun nanofibers and the electrospinnability zones, the Berry number was used. However, as its only allows the range of electrospinnability to be established for a fixed solvent composition, a new dimensionless parameter (Bemod) was suggested to take into account all the acetic acid aqueous solutions as a single solvent
Sistema y procedimiento de infusión de resina por vacío para la obtención de piezas elaboradas a partir de materiales compuestos, así como la pieza obtenida mediante dicho procedimiento, comprendiendo el sistema un par de diafragmas flexibles y vinculables entre sí tal que se define un espacio entre ambos diafragmas flexibles para la disposición de una preforma; comprendiendo adicionalmente unos medios de encapsulamiento dispuestos entre los diafragmas flexibles, en el que los medios de encapsulamiento comprenden una bolsa de vacío configurada para albergar una preforma, y unos medios de moldeo posicionados por debajo del diafragma flexible inferior o por encima del diafragma flexible superior y que comprenden un cuerpo de molde sobre una superficie de vacío, estando adaptada dicha superficie de vacío tal que se genera una cavidad sellada cuando se vincula a alguno de los diafragmas flexibles.
Serafini, A.; Lis, M.; Carreras, N.; Boemo, R.L.; Tornero, J. Materials science and engineering C. Biomimetic and supramolecular systems Vol. 33, num. 7, p. 4002-4008 DOI: 10.1016/j.msec.2013.05.034 Data de publicació: 2013-10 Article en revista
The primary advantages of electrospun membranes include the ability to obtain very thin fibers that are on the order of magnitude of several nanometers with a considerable superficial area and the possibility for these membranes to be manipulated and processed for many different applications. The purpose of this study is to evaluate and quantify the transport mechanisms that control the release of drugs from polymer-based sandwich membranes produced using the electrospinning processes. These electrospun membranes were composed of poly(lactic acid) (PLA) because it is one of the most promising biodegradable polymers due to its mechanical properties, thermoplastic processability and biological properties, such as its biocompatibility and biodegradability. The transport mechanism that controls the drug delivery was evaluated via the release kinetics of a bioactive agent in physiological serum, which was used as a corporal fluid simulation. To describe the delivery process, mathematical models, such as the Power Law, the classical Higuchi equation and an approach to Fick's Second Law were used. Using the applied mathematical models, it is possible to conclude that control over the release of the drug is significantly dependent on the thickness of the membrane rather than the concentration of the drug.