Simulation of plasmonic effects of Metal (Au,Ag and Al) NPs and rGO embedded in aqueous solutions

Graphene [1] is a material that has been extensively explored in recent years as a material with optical properties that enable its application as active material in sensing devices.In this work we will study plasmonic effects and optical properties of graphene and metal nanoparticles (AuNPs), comparing its results, whenever possible, with results obtained in previous studies. Analysis will be supported by simulation results obtained with Matlab (“Mie analysis”)

VLC system for the determination of a vehicle’s position and speed

In recent years, lighting solutions have gradually been replaced by more efficient features, taking advantage of Light Emitting Diodes (LEDs) that have progressively conquered the market with increasingly high optical powers, low energy consumption and variable color temperatures. Along with this evolution, Visible Light Communication (VLC) technology has also been developed to use this existing lighting infrastructure and the inherent characteristic of LEDs being easily switched to high frequency to build data transmission systems. The applications of this communication technology using electromagnetic signals in the visible range are currently in a development stage with promising applications in several domains.This paper intends to study an optical communication system based on VLC to establish communication between road infrastructures and. vehicles. For this purpose, four communication channels established through the modulation of white trichromatic LED emitters are used. Detection of the optical signals is performed with a photodiode based on two stacked pin structures made of a-Si:H and a-SiC:H. This device works as an optical filter in the visible spectrum and its spectral sensitivity can be adjusted through stationary optical bias. On-Off-Keying (OOK) modulation is used. The structure of the data blocks to be transmitted was designed to avoid undesirable effects related to ambient light (flickering and/or perceptible variations in color temperature of the white light). The experimental tests of the proposed model were performed using a small-scale prototype. The results show that with the proposed system it is possible to transmit information between road infrastructure and vehicles. 

Tuning the spectral distribution of p-i-n a-SiC : H devices for colour detection

ZnO:Al/p (SiC:H)/i (Si:H)/n (SiC:H) large area image and colour sensor are analysed. Carrier transport and collection efficiency are investigated from dark and illuminated current-voltage (I-V) dependence and spectral response measurements under different optical and electrical bias conditions. Results show that the carrier collection depends on the optical bias and on the applied voltage. By changing the electrical bias around the open circuit voltage it is possible to filter the absorption at a given wavelength and so to tune the spectral sensitivity of the device. Transport and optical modelling give insight into the internal physical process and explain the bias control of the spectral response and the image and colour sensing properties of the devices

Stacked pin devices for imaging applications

In this paper we present results on the optimization of device architectures for colour and imaging applications, using a device with a TCO/pinpi'n/TCO configuration. The effect of the applied voltage on the color selectivity is discussed. Results show that the spectral response curves demonstrate rather good separation between the red, green and blue basic colors. Combining the information obtained under positive and negative applied bias a colour image is acquired without colour filters or pixel architecture. A low level image processing algorithm is used for the colour image reconstruction

A non-pixel image reader for continuous image detection based on tandem heterostructures

An optically addressed read-write sensor based on two stacked p-i-n heterojunctions is analyzed. The device is a two terminal image sensing structure. The charge packets are injected optically into the p-i-n writer and confined at the illuminated regions changing locally the electrical field profile across the p-i-n reader. An optical scanner is used for charge readout. The design allows a continuous readout without the need for pixel-level patterning. The role of light pattern and scanner wavelengths on the readout parameters is analyzed. The optical-to-electrical transfer characteristics show high quantum efficiency, broad spectral response, and reciprocity between light and image signal. A numerical simulation supports the imaging process. A black and white image is acquired with a resolution around 20 mum showing the potentiality of these devices for imaging applications

Desarrollo de sistemas de alerta y de métodos de identificación y detección de toxinas marinas

Las toxinas marinas son productos secundarios con actividad tóxica, originados por el metabolismo de algunas especies de microalgas fitoplanctónicas (dinoflagelados, diatomeas y cianobacterias) y también ciertas bacterias. Las toxinas son concentradas preferentemente por la filtración de los bivalvos y encontradas en moluscos, peces, crustáceos y en diversos animales acuáticos como consecuencia de su distribución en la cadena alimentaria marina. El incremento en la frecuencia de las floraciones de microalgas tóxicas, así como la aparición de nuevas toxinas marinas, posiblemente como consecuencia del cambio climático es un problema global de salud pública, debido al gran número de intoxicaciones alimentarias que producen y a las pérdidas económicas en el sector marítimo y pesquero. De hecho muchos países, especialmente aquellos con importantes industrias en la acuicultura y la pesca tienen hoy en día programas de vigilancia para la detección de las microalgas en la columna de agua y los niveles de toxinas en los moluscos. Sin embargo, es necesario implantar sistemas de monitorización más efectivos e integrados en el tiempo y el espacio, que permitan controlar tanto la presencia de microalgas tóxicas en el agua del mar como las toxinas producidas antes de que estos productos se acumulen en los moluscos bivalvos. En este contexto, el trabajo de tesis doctoral está relacionado con la detección de toxinas marinas, principalmente del grupo de la TTX, STX y toxinas lipofílicas en diferentes muestras (moluscos, peces, dinoflagelados, gasterópodos…) y con la monitorización de algunas de estas toxinas en el agua del mar. Todo el trabajo está recogido en 6 artículos publicados en revistas internacionales y un artículo pendiente de publicación

Interactive effects of aflatoxin M1 and ochratoxin A in a human intestinal cell line: evaluation of cyto- and genotoxicity

Aflatoxins (AF) and ochratoxin A (OTA) are frequent contaminants of foodstuff and low doses of these mycotoxins have been shown to co-occur in baby foods. Our objective was to investigate whether a combined intake of AFM1 and OTA could alter the cytotoxic and genotoxic effects of the single mycotoxins. These effects were assessed by the Neutral Red and the Comet assays, following exposure of Caco-2 cells to individual and combined doses of the two mycotoxins. A dose-dependent cytotoxic response was observed for OTA, whereas AFM1 was cytotoxic only at the highest dose (10BM). Among the several combinations of OTA (2.5, 5 and 10BM) and AFM1 (0.5, 1, 2.5, 5 and 10BM) tested for cytotoxicity, some displayed interactive effects. Noteworthy, combination of 2.5 BM of OTA and 0.5 BM of AFM1, significantly increased the cytotoxicity, as compared to each toxin taken alone, suggesting a synergistic effect. Preliminary data from the comet assay did not show significant induction of DNA damage, neither for single mycotoxins nor for their mixtures. In conclusion, our data suggest the existence of interactive cytotoxic effects between OTA and AFM1. The possible synergism observed between the lowest concentrations of both mycotoxins, which are closer to the realistic doses of human exposure, might be particularly relevant for children, who are more vulnerable to toxic effects

A Flexible Amorphous Silicon Photovoltaic Module for Portable Electronics

This article reports on a monolithic 10 cm × 10 cm area PV module integrating an array of 72 a-Si:H n-i-p cells on a thin polyethylene-naphtalate substrate. The design optimization and device performance analysis are performed using a two-dimensional distributed circuit model of the photovoltaic cell. Experimental results show that the shunt leakage is one of the factors reducing the device performance. Using the LBIC technique, the multiple micro-shunts in the n‑i‑p cell were detected. The mechanism of electrical shunts formation is proposed and discussed

A saúde reprodutiva das mulheres migrantes em Niamey [Níger]: Trajetórias terapêuticas e dinâmicas glocais

As incessáveis reformas promovidas pelos organismos internacionais, durante as últimas décadas, nos serviços de saúde de alguns países do Sul Global, pouco têm contribuído para aproximar as mulheres mais pobres dos cuidados biomédicos. Este trabalho analisa a subutilização dos serviços de saúde públicos a partir das trajetórias terapêuticas realizadas por um grupo de mulheres migrantes residentes em Niamey, República do Níger. A pesquisa etnográfica realizada junto de um grupo significativo de mulheres migrantes, de terapeutas e de profissionais de saúde, revelou que o pluralismo terapêutico e o atendimento irregular de cuidados biomédicos têm que ser entendidos à luz dos constrangimentos locais e das forças históricas globais. Verificou-se que a promoção da saúde da mulher não pode se circunscrever a um pacote de medidas biomédicas. A forma como a pobreza é gerida no quotidiano é uma dimensão que os decisores políticos internacionais deveriam ter em conta na formulação das suas políticas.The incessant reforms promoted by international organizations over the past few decades in health services in many countries of the Global South have contributed little to bringing the poorest women closer to biomedical care. This thesis focus on the underutilization of public health services, departing from the analysis of the therapeutic trajectories carried out by a group of migrant women living in Niamey, Republic of the Niger. Ethnographic research carried out with a significant group of migrant women, therapists and health professionals has revealed that therapeutic pluralism and irregular attendance of biomedical services have to be understood in the light of local constraints and global historical forces. It was found that the promotion of women's health cannot be limited to a package of biomedical measures. The way poverty is managed in everyday life is a dimension that international policy-makers should take into account in formulating their policies

Visible Light Communication in Vehicular Communication Applications

This paper addresses the issues related to the Visible Light Communication (VLC) usage in vehicular communication applications. We propose a Visible Light Communication system based on Vehicle-to-Vehicle, Vehicleto-Infrastructure and Infrastructure-to-Vehicle communications able to safely manage vehicles crossing through an intersection. By using the streetlamps, street lights and traffic signaling to broadcast information, the connected vehicles interact with one another and with the infrastructure. Using joint transmission, mobile optical receivers collect data, calculate their location for positioning and, concomitantly, read the transmitted data from each transmitter. As receivers and decoders, optical sensors with light filtering properties, are used. Bidirectional communication between the infrastructure and the vehicles is tested. To command the passage of vehicles safely queue/request/response mechanisms and temporal/space relative pose concepts are used. The results show that the innovative solutions for congested intersections are related to the introduction of split intersections. The results indicate that the V-VLC system increases safety by directly monitoring critical points such as queue formation and dissipation, relative speed thresholds, as well as inter-vehicle spacing.publishersversionpublishe