Correlation between optical and electrical properties of materials containing nanoparticles

Consultable des del TDXTítol obtingut de la portada digitalitzadaEn esta tesis, capas de óxido de silicio rico en silicio [SRO, (SiOx, x<2)] con diferentes excesos de silicio fueron depositadas por medio de la técnica de depósito químico en fase vapor a baja presión (LPCVD). Un segundo conjunto de muestras de SRO implantadas con silicio (SI-SRO) adicional fueron también fabricadas. Nanopartículas de silicio (Si-nps) en estas capas fueron creadas después de someter a las muestras a un tratamiento térmico en alta temperatura (1100 y 1250º C). La composición, microestructura y propiedades ópticas de estas capas de SRO y SI-SRO fueron analizadas en función de los diferentes parámetros tecnológicos, tales como exceso de silicio, implantación de silicio, así como de la temperatura de tratamiento térmico. Una vez conocido la microestructura, composición y propiedades ópticas de estos materiales, capas de SRO que exhibieron la mejor propiedad fotoluminiscente (FL más intensa) fueron escogidas para analizar sus propiedades eléctricas y electro-ópticas; estructuras Metal-Óxido-Semiconductor (MOS) fueron fabricadas usando las capas de SRO como material dieléctrico para tales estudios. Capas de SRO con exceso de silicio de ~4.0 and ~2.2 at.% y grosores de entre 24 y 80 nm fueron depositadas. El mecanismo de conducción en estas películas es analizado haciendo uso de modelos como tuneleo asistido por trampas (TAT) y tuneleo Fowler-Nordheim (FN) en bajos y altos campos eléctricos, respectivamente. Las mediciones eléctricas mostraron importantes resultados tales como una reducción en la capacitancia y corriente durante el barrido de voltaje o después de estresar eléctricamente los dispositivos. Dichos efectos son relacionados con la aniquilación de caminos conductivos que son creados por nanoclusters de silicio (Si-cls) que se encuentran dispersados dentro de la película de SRO. Además de lo anterior, algunos dispositivos exhibieron fluctuaciones en la corriente en la forma de picos y un comportamiento de escalera muy claro a temperatura ambiente. Dichos efectos son relacionados con los llamados efectos de bloqueo Coulómbico (CB) que se presentan en las nanopartículas de silicio que se encuentran dentro de las capas de SRO. A partir del ancho de cada escalón se pudo estimar el tamaño (cerca de 1 nm) de las nanopartículas. Estudios de luminiscencia de efecto de campo en las capas de SRO son estudiados por excitar los dispositivos con pulsos de voltaje. Además de la electroluminiscencia (EL) pulsada, es mostrado que estos dispositivos también muestran EL en voltaje continuo, donde la emisión es observada como múltiples puntos brillantes de varios colores sobre la superficie de los dispositivos cuando estos son polarizados en inversa. El espectro de emisión en dichos dispositivos es amplio y va desde 400 hasta 900 nm. Finalmente, una correlación entre las propiedades microestructurales, eléctricas y luminiscentes (FL y EL) es analizada y discutida.In this thesis, silicon rich oxide [SRO, (SiOx, x<2)] films with different silicon excesses were deposited by low pressure chemical vapor deposition (LPVCD). Besides, Si implanted SRO (SI-SRO) films were also fabricated. Si-nps in these films were created after a thermal annealing at high temperature (1100 and 1250º C). The composition, microstructure and optical properties of these SRO and SI-SRO films were analyzed as a function of the different technological parameters, such as silicon excess, Si ion implantation dose, and thermal annealing temperature. Once the microstructure, composition as well as the optical properties of these materials is known, SRO films which exhibited the best photoluminescent (strongest PL) properties were chosen in order to analyze their electrical and electro-optical properties. Simple Metal-Oxide-Semiconductor (MOS) structures using the SRO films as the dielectric layer were fabricated for these studies. SRO films with Si-excess of ~4.0 and ~2.2 at.% and thickness ranging from 24 to 80 nm were deposited. The conduction mechanism in these films is analyzed by making use of trap assisted tunnelling (TAT) in low electric field as well as Fowler-Nordheim (FN) tunnelling in high electric fields. The electrical measurements exhibited important results, such as a reduction in capacitance and current during the sweep or after applying a constant bias. These effects are ascribed to the annihilation of conduction paths created by silicon clusters (Si-cls) inside the SRO films. A part from that, some devices exhibited current fluctuations in the form of spike-like peaks and a clear staircase at room temperature. These effects were related to Coulomb blockade (CB) effects in the silicon nanoparticles embedded in the SRO films. And from the current plateaus, the size of the Si-nps (about 1 nm) was calculated. Field effect luminescence of these SRO films was studied by alternating negative (positive) to positive (negative) voltages (pulsed excitation). Moreover, it is demonstrated that these SRO films show EL emission in continuous current voltage, observed at naked eye. Multiple shining spots of several colours are seen on the MOS-like structure surface when reversely biased. These devices display a broad electroluminescent emission spectrum which goes from 400 nm up to 900 nm. Finally, a correlation between the structural, electrical and luminescent (PL and EL) properties is discussed

Monolithically Integrable Si-Compatible Light Sources

On the road to integrated optical circuits, the light emitting device is considered the bottleneck preventing us from arriving to the fully monolithic photonic system. While the development of silicon photonics keeps building momentum, the indirect bandgap nature of silicon represents a major problem for obtaining an integrated light source. Novel nanostructured materials based on silicon, such as silicon-rich oxide (SRO) containing silicon nanoparticles, present intense luminescence due to quantum phenomena. Using this material, electroluminescent devices have already been fabricated and even integrated in monolithic photonic circuits by fully complementary metal oxide semiconductor (CMOS) compatible techniques, opening the door to seamless electronic and photonic integration. The present work discusses some of the strategies used to improve the performance of SRO-based electroluminescent devices fully compatible with CMOS technology. Results from the characterization of devices obtained using different approaches are presented and compared

Novel tuffite/Fe-Cu oxides nanocomposite with functionality for dye removal in aqueous solution

Fe-Cu oxides nanoparticles were embedded on tuffite (TUF) mineral by means of a simple immersion-ion impregnation, followed by a reduction reaction, methodology. TUF/Fe-Cu nanocomposite characteristics were investigated by XRD, TEM, BET, SEM, FT-IR spectroscopy and pHzpc method. Fe-Cu nanostructures with mean sizes between 10 and 20 nm were effectively supported on TUF. Because of its functional properties, the nanocomposite was studied as adsorbent material for the degradation of Malachite Green (MG) organic dye in aqueous solution. The adsorption kinetic data was well-fitted to pseudo first-order model, indicating physisorption as the main mechanism of adsorption. High pH and temperature of the solution favored malachite green adsorption. The adsorption process was spontaneous and endothermic. In comparative sorption experiments with different dyes, the nanocomposite showed better removal capacities for cationic and basic than for anionic and acid dyes. Langmuir, Freundlich, Langmuir-Freundlich and Temkin models were applied to evaluate the isotherms, resulting in an adsorption capacity of 376.66 mg/g, which is above most of the adsorbent materials so far employed for malachite green degradation in aqueous solution. Therefore, this novel, easy to prepare and low-cost nanocomposite proved to have synergic functionality as an efficient adsorbent material for cationic organic dyes.UAEM/2708/2013 and 3688/2014/CIB projects. Scholar-ship Grant No. 289993CONACYT

Brood parasitism, provisioning rates and breeding phenology of male and female magpie hosts

Parental care is a costly behaviour that raises the prospects of offspring survival. In species with biparental care these costs are shared by both parents, although there may be a conflict regarding the relative investment of each sex. Avian brood parasites leave all the costs of rearing offspring to their hosts. The magnitude of these costs and their consequences on the relative role of both sexes in parental care and future reproduction remain mostly unknown. Here, we investigate whether provisioning rate of nestlings by magpie hosts Pica pica differs between broods parasitized by the great spotted cuckoo Clamator glandarius and non-parasitized broods, and whether the relative contribution of each sex to provisioning is affected by parasitism. Furthermore, we explore the effect of parasitism on magpie’s future reproduction. We found that provisioning rate was similar in parasitized and non-parasitized broods, and that the relative contribution of males and females was also similar, irrespectively of the parasitism status. However, rearing parasitic offspring seems to have a negative long-term effect on magpie’s breeding phenology in the following breeding season. Our results suggest that, although brood parasitism by great spotted cuckoos does not seem to influence the relative contribution of both sexes to parental care, it may entail long-term extra costs in terms of breeding delay for magpies.Junta de Andalucía (Proyecto P06-RNM-01862)Ministerio de Ciencia (proyecto CGL2014-55362-P)Programa Juan de la Cierva –Incorporación (IJC2018-036411-I)German Research Foundation (SFB TRR 212 (NC3) – Projectos n. 316099922 y 396782608

On the efficient delivery and storage of IoT data in edge-fog-cloud environments

This article belongs to the Special Issue Internet of Things, Sensing and Cloud ComputingCloud storage has become a keystone for organizations to manage large volumes of data produced by sensors at the edge as well as information produced by deep and machine learning applications. Nevertheless, the latency produced by geographic distributed systems deployed on any of the edge, the fog, or the cloud, leads to delays that are observed by end-users in the form of high response times. In this paper, we present an efficient scheme for the management and storage of Internet of Thing (IoT) data in edge-fog-cloud environments. In our proposal, entities called data containers are coupled, in a logical manner, with nano/microservices deployed on any of the edge, the fog, or the cloud. The data containers implement a hierarchical cache file system including storage levels such as in-memory, file system, and cloud services for transparently managing the input/output data operations produced by nano/microservices (e.g., a sensor hub collecting data from sensors at the edge or machine learning applications processing data at the edge). Data containers are interconnected through a secure and efficient content delivery network, which transparently and automatically performs the continuous delivery of data through the edge-fog-cloud. A prototype of our proposed scheme was implemented and evaluated in a case study based on the management of electrocardiogram sensor data. The obtained results reveal the suitability and efficiency of the proposed scheme.This research was funded by the project 41756 "Plataforma tecnológica para la gestión, aseguramiento, intercambio y preservación de grandes volúmenes de datos en salud y construcción de un repositorio nacional de servicios de análisis de datos de salud" by the PRONACES-CONACYT

Nephrotoxicity biomarkers able to identify oncological patients at risk of developing kidney damage

Cisplatino y carboplatino son dos fármacos muy usados en el tratamiento de tumores sólidos. Sin embargo, su eficacia está limitada por su nefrotoxicidad. Se ha demostrado que un 25-30% de los pacientes tratados con estos fármacos ha acabado desarrollando un daño renal agudo (DRA). En la actualidad, el diagnóstico del DRA se lleva a cabo mediante el uso de biomarcadores tales como creatinina plasmática y urea, pero resultan poco sensibles y específicos. El objetivo de este trabajo se centra en la búsqueda de biomarcadores urinarios capaces de predecir la aparición de un fallo renal, antes incluso de comenzar dicho tratamiento, siendo capaces de clasificar a los pacientes de acuerdo con su sensibilidad, predecir la evolución de su función renal y llevar a cabo un tratamiento más adaptado a cada paciente./nUn estudio clínico fue llevado a cabo con pacientes voluntarios del Servicio de Oncología del Hospital Universitario de Salamanca. Los biomarcadores estudiados fueron proteinuria, N-acetil-?-glucosaminidasa (NAG), Lipocalina asociada a la gelatinada de neutrófilos (NGAL) y albúmina. Para la cuantificación de estos biomarcadores se utilizaron técnicas colorimétricas y la técnica ELISA./nLos resultaron mostraron que los niveles de los biomarcadores en el grupo Casos son significativamente superiores a los del grupo Control, tanto en el momento anterior al máximo daño renal, como en el momento basal, lo que nos permitiría saber cuáles son los pacientes que tendrían más probabilidad de sufrir un daño renal antes de iniciar el tratamiento. Dichos marcadores serían un gran avance en el tratamiento quimioterápico, ya que nos permitirían un tratamiento más preventivo y personalizado de cada paciente.Cisplatin and carboplatin are very used drugs for the treatment of solid tumours. However, their efficacy is limited by their nephrotoxicity. It is known that 25-30% of the patients that have been exposed to these treatments will end up developing acute kidney injury (AKI). Nowadays, for the clinical diagnosis of AKI some biomarkers are used, such as plasma creatinine and urea, which are not very sensitive and specific. The aim of this work is focused on searching some urinary biomarkers able to predict the occurrence of a possible kidney damage even before starting the treatment, being able to classify the patients according to their severity, to predict the evolution of kidney function and to carry out a more adapted treatment for every patient./nA clinical study was carried out with voluntary patients from the Oncology Service of the University Hospital of Salamanca. The studied biomarkers were proteinuria, N-acetil-?-glucosamidinase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and albumin. The quantification of these proteins in urine was performed by colorimetric methods and ELISA./nIt was evidenced that the levels of the biomarkers in the basal time and in the one before the maximum kidney damage are practically the same, what indicates that these levels do not vary during the chemotherapy cycle. Moreover, they could indicate, before starting the treatment, that kidney damage is going to happen. These biomarkers would be a great advantage in determining, before undergoing the first chemotherapy cycle, whether a patient will suffer kidney complications

Uso de la microtenotomía por radiofrecuencia con el dispositivo Topaz® para el tratamiento de la tendinopatía aquílea no insercional

Achilles tendon injuries are a common disease in podiatric and foot and ankle surgery consultation. Midportion pain is a frequent problem in runners but could be seen in sedentary people too. Correct term for this condition is non insertional Achilles tendinopathy. There are many treatment options that try to reduce the pain and improve the function of damaged tissue. Conservative treatments usually have good results but there are some cases that could need surgery. We present a minimally invasive technique using a radiofrequency microdebrider to treat the tendinosis.Las lesiones del tendón de Aquiles son un motivo frecuente de consulta en el ámbito de la podología y de la cirugía del pie y tobillo. El dolor del tercio medio del tendón es un problema habitual en corredores, pero también se ve en pacientes sedentarios. El término correcto para referirnos a esta lesión es el de tendinopatía aquílea no insercional. Existen numerosos tratamientos que intentan disminuir el dolor y mejorar la función del tejido lesionado. Los medios conservadores suelen tener buenos resultados, pero existe un porcentaje de pacientes que precisan cirugía. Presentamos una técnica poco invasiva para esta patología en la que utilizamos un dispositivo de radiofrecuencia para tratar la tendinosis

Synthesis and Luminescent Properties of Silicon Nanocrystals

Nowadays, study of silicon-based visible light-emitting devices has increased due to large-scale microelectronic integration. Since then different physical and chemical processes have been performed to convert bulk silicon (Si) into a light-emitting material. From discovery of Photoluminescence (PL) in porous Silicon by Canham, a new field of research was opened in optical properties of the Si nanocrystals (Si-NCs) embedded in a dielectric matrix, such as SRO (silicon-rich oxide) and SRN (silicon-rich nitride). In this respect, SRO films obtained by sputtering technique have proved to be an option for light-emitting capacitors (LECs). For the synthesis of SRO films, growth parameters should be considered; Si-excess, growth temperature and annealing temperature. Such parameters affect generation of radiative defects, distribution of Si-NCs and luminescent properties. In this chapter, we report synthesis, structural and luminescent properties of SRO monolayers and SRO/SiO2 multilayers (MLs) obtained by sputtering technique modifying Si-excess, thickness and thermal treatments

Second Metatarsophalangeal joint Synovitis: Update

En las consultas de podología es común la existencia de numerosos procesos patológicos que desarrollan episodios inflamatorios en la cápsula articular de las articulaciones metatarsofalángicas (AMTF) y de sus estructuras vecinas como el plato glenoideo o los ligamentos colaterales, pero no son reconocidas claramente. Diferentes autores lo han explicado como el compromiso articular generado por un proceso de inestabilidad de etiología diversa y que evoluciona en diferentes estadíos, cada uno de los cuales posee diferentes grados de afectación a nivel de esa articulación. Esta patología se localiza en la articulación metatarsofalángica del segundo dedo con mayor prevalencia sobre el tercero en la mayoría de los casos de la bibliografía consultada, siendo reconocida como una de las causas potenciales de metatarsalgias. Los procesos biomecánicos anómalos que sobrecargan las estructuras de antepie pueden provocar una inflamación de la cápsula sinovial que delimita la articulación, disminuyendo progresivamente la movilidad del dedo y agravando la progresión de la patología.In podiatric clinics is very common to find inflamatory process in metatarsophalangeal joint capsule , plantar plate and collateral ligaments damage, but it is not clearly recognized. Many authors hipotetized with joint instability of multiple aetiology and his concomitant evolution in different stages with own joint disease. This pathology has more incidence in second metatarsophalangeal joint than third and others and it is a common etiology of metatarsal pain. Bad biomechanics alters forefoot function and can produce overload in capsular joint, decreasing mobility and getting worse the pathology

La regulación del derecho a la autodeterminación informativa en El Salvador

El derecho a la Autodeterminación Informativa tiene por objeto dotar a las personas de un control sobre sus datos personales a través de una serie de principios y facultades, los cuales han sido cambiantes desde el origen de este derecho, debido al desarrollo acelerado que ha sufrido la tecnología y con ella la recolección y tratamiento de datos personales, por lo que es fácil predecir que ante esta realidad el Derecho a la Autodeterminación Informativa se encuentra todavía en constante evolución. Este derecho en la doctrina y en la legislación comparada ha alcanzado un gran desarrollo, regulando temas relativos a la información de las personas en redes sociales y en buscadores de internet (derecho al olvido), además de los datos en la nube (derecho a la portabilidad), el control del procesamiento de datos personales en el extranjero, la transferencia de datos al extranjero y un ente administrativo que vela por el cumplimiento de la legislación relativa a la protección de datos. El Salvador no es ajeno a las causas que originan la necesidad de la regulación del tratamiento de datos personales, Es indiscutible además que existe desarrollo del derecho a la autodeterminación informativa, tanto a nivel jurisprudencial como legislativo, pero este es insuficiente ya que la legislación es dispersa, se encuentra restringida por su propio ámbito de aplicación y no corresponde al desarrollo tecnológico actual. Por lo antes expuesto, existe la necesidad de crear una ley que regule la protección de datos de carácter personal adaptada a las exigencias tecnológicas, incorporando las facultades y principios ya establecidos en doctrina y el derecho comparado