Estrategias de fotorreticulación alternativas a la fotopolimerización de acrilatos para la preparación de materiales microestructurados de uso en aplicaciones biomédicas

El proyecto de la esta tesis doctoral se centra en el estudio de dos nuevas estrategias de fotopolimerización alternativas a la fotopolimerización radicalaria de acrilatos que permitan la preparación de materiales biocompatibles y microestructurados con potencial uso en aplicaciones biomédicas. Con este fin, se ha estudiado la posibilidad de reticular polímeros biodegradables mediante reacciones fotoinducidas en las que, por acción de la luz, se produzca una reacción entre dos grupos funcionales. De esta forma, partiendo de un polímero biodegradable con uno de los dos grupos funcionales y de un reticulante multifuncional de bajo peso molecular que contenga el otro grupo funcional, se puede generar una red polimérica que, tras ser degradada, va a generar únicamente fragmentos de bajo peso molecular. Esto representa una ventaja respecto a la tradicional estrategia de entrecruzamiento por fotopolimerización radicalaria de acrilatos, tradicionalmente usada en la generación de biomateriales, ya que esta reacción genera cadenas acrílicas no biodegradables que tienen un mayor riesgo de acumularse en el organismo y provocar una respuesta tóxica en el mismo. Las dos reacciones estudiadas son la descomposición fotoinducida de sales de diazonio y la química de tiol-inos. La primera está basada en la descomposición fotoinducida de los grupos diazonio aromáticos que generan una especia aromática capaz de reaccionar con grupos nucleófilos como los presentes en muchos polímeros naturales como diversos polisacáridos. Además esta reacción transcurre en disolución acuosa lo que representa una ventaja para este tipo de polímeros que pueden verse afectados por disolventes orgánicos. Respecto a la química de tiol-inos, resulta una manera eficiente de entrecruzar polímeros (tal y como se ha descrito en la bibliografía aunque no en la generación de biomateriales) y presentaría ciertas ventajas respecto a la química de tiol-enos, que ya se ha estudiado para esta aplicación. Entre estas ventajas cabe destacar la posibilidad de obtener redes con un mayor entrecruzamiento, lo cual puede ser ventajoso en algunas aplicaciones. Además, controlando la composición de la formulación fotopolimerizable y la presencia de grupos tiol o alquino sin reaccionar en el material entrecruzado, se podría llevar a cabo una funcionalización del material entrecruzado mediante reacción de los grupos alquino o tiol libres. Esto permitiría funcionalizar la superficie del material con biomoléculas que podrían inducir una determinada respuesta en las células cultivadas. En esta tesis doctoral se han utilizado estas dos reacciones para llevar a cabo el entrecruzamiento de polímeros naturales o sintéticos (en algunos casos modificados para introducir grupos fotorreactivos) y obtener de esta forma materiales biocompatibles. Estos materiales se procesaron en forma de película para ser utilizados como sustrato para el cultivo celular y estudiar así la biocompatibilidad de los mismos como andamiaje para las células. Por otro lado, se aplicaron también técnicas de escritura láser para generar patrones poliméricos en películas de preparadas para estas formulaciones. Estos patrones se generaron con distintos motivos o parámetros geométricos y fueron igualmente utilizados como sustrato para el cultivo celular. De esta forma se estudió como influyen algunos de estos parámetros en el comportamiento celular

Modelado dinamico y control de un robot flexible de tres grados de libertad

Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai

EM Modelling of Monostatic RCS for Different Complex Targets in the Near-Field Range: Experimental Evaluation for Traffic Applications

An evaluation of monostatic radar cross section (RCS) response in the near-field range was performed for several targets with different and complex topologies. The main objective was to provide and validate an efficient tool based on electromagnetic (EM) simulations to characterize a traffic scenario. Thus, a novel method based on the combination of geometrical theory of diffraction (GTD) and physical optics (PO) was used to estimate RCS, and the results were compared with the method of moments (MoM) methodology. The simulations were experimentally validated using a commercial vehicular frequency-modulated continuous wave (FMCW) radar at 24 GHz. With this simple measurement system, RCS measurements can be made using an easier and cheaper process to obtain RCS response in the near-field range, which is the most usual situation for traffic applications. A reasonable agreement between the measurements and the EM simulations was observed, validating the proposed methodology in order to efficiently characterize the RCS of targets typically found in real traffic scenarios

Angular deficits in flat space: remotely controllable apertures in nematic solid sheets

Recent attention has been given to the realization of angular deficits and surpluses in the local ground-state geometry of thin sheets of nematic solids as out-of-plane deformations. Such systems exhibit conical or anti-conical curvature sites, or possibly arrays of such polyhedral corners, in order to satisfy the material's spontaneous strain-generated metric requirements. Here, we turn the angular deficit requirement on its head, and show theoretically and experimentally that by appropriately altering the topology of the initially flat sheet-for example, by cutting it in carefully chosen regions-the same angular deficits and surpluses may manifest simply in-plane by changing the geometry of the cut region. Such amechanism offers a route to apertures or arrays of apertures that may be reversibly opened and closed by applying spontaneous strain with heat, light or chemical potential

Mechanical frustration and spontaneous polygonal folding in active nematic sheets

We analyze the bending response to light or heat of a solid nematic disk with a director twisted from being radial on the upper surface to be azimuthal on the lower. We find a number of curl lobes determined purely by the geometry of the mechanical frustration that arises during the response

Engineered complex molecular order in liquid crystals towards unusual optics and responsive mechanics

Defects in liquid crystals have been studied over decades to disclose information and knowledge on the structure of LC phases. More recently, LC defects have been identified as a tool to implement new physical functions useful in optical films for polarization conversion or mechanical actuators able to adopt novel exotic shapes. In the present paper we describe a general methodology to engineer different defect patterns by combining the use of linear photopolymerizable polymers and liquid crystals

Mechanical frustration and spontaneous polygonal folding in active nematic sheets

We analyze the bending response to light or heat of a solid nematic disk with a director twisted from being radial on the upper surface to be azimuthal on the lower. We find a number of curl lobes determined purely by the geometry of the mechanical frustration that arises during the response

Saccharomyces cerevisiae Fungemia: An Emerging Infectious Disease

Producción CientíficaBackground: Saccharomyces cerevisiae is well known in the baking and brewing industry and is also used as a probiotic in humans. However, it is a very uncommon cause of infection in humans. Methods: During the period of 15–30 April 2003, we found 3 patients with S. cerevisiae fungemia in an intensive care unit (ICU). An epidemiological study was performed, and the medical records for all patients who were in the unit during the second half of April were assessed. Results: The only identified risk factor for S. cerevisiae infection was treatment with a probiotic containing Saccharomyces boulardii (Ultralevura; Bristol-Myers Squibb). This probiotic is used in Europe for the treatment and prevention of Clostridium difficile–associated diarrhea. The 3 patients received the product via nasograstric tube for a mean duration of 8.5 days before the culture result was positive, whereas only 2 of 41 control subjects had received it. Surveillance cultures for the control patients admitted at the same time did not reveal any carriers of the yeast. Strains from the probiotic capsules and the clinical isolates were identified as S. cerevisiae, with identical DNA fingerprinting. Discontinuation of use of the product in the unit stopped the outbreak of infection. A review of the literature identified another 57 cases of S. cerevisiae fungemia. Overall, 60% of these patients were in the ICU, and 71% were receiving enteral or parenteral nutrition. Use of probiotics was detected in 26 patients, and 17 patients died. Conclusions: Use of S. cerevisiae probiotics should be carefully reassessed, particularly in immunosuppressed or critically ill patients.Red Española de Investigación en Patología Infecciosa (REIPI-C03/14

Service for the Pseudonymization of Electronic Healthcare Records Based on ISO/EN 13606 for the Secondary Use of Information.

The availability of electronic health data favors scientific advance through the creation of repositories for secondary use. Data anonymization is a mandatory step to comply with current legislation. A service for the pseudonymization of electronic healthcare record (EHR) extracts aimed at facilitating the exchange of clinical information for secondary use in compliance with legislation on data protection is presented. According to ISO/TS 25237, pseudonymization is a particular type of anonymization. This tool performs the anonymizations by maintaining three quasi-identifiers (gender, date of birth, and place of residence) with a degree of specification selected by the user. The developed system is based on the ISO/EN 13606 norm using its characteristics specifically favorable for anonymization. The service is made up of two independent modules: the demographic server and the pseudonymizing module. The demographic server supports the permanent storage of the demographic entities and the management of the identifiers. The pseudonymizing module anonymizes the ISO/EN 13606 extracts. The pseudonymizing process consists of four phases: the storage of the demographic information included in the extract, the substitution of the identifiers, the elimination of the demographic information of the extract, and the elimination of key data in free-text fields. The described pseudonymizing system was used in three telemedicine research projects with satisfactory results. A problem was detected with the type of data in a demographic data field and a proposal for modification was prepared for the group in charge of the drawing up and revision of the ISO/EN 13606 norm.This work was supported inpart by Project PI08/1148, Project PI08/90330, Project PI12/01476, and ProjectPI12/01305 (coord. PI12/00508) from Fondo de Investigaci ́on Sanitaria (FIS)Plan Nacional de I+D+i and by Project CEN-20091043S