Research lines in Hyperthermia at the Bioinstrumentation Laboratory of the Centre for Biomedical Technology

The Bioinstrumentation Laboratory belongs to the Centre for Biomedical Technology (CTB) of the Technical University of Madrid and its main objective is to provide the scientific community with devices and techniques for the characterization of micro and nanostructures and consequently finding their best biomedical applications. Hyperthermia (greek word for “overheating”) is defined as the phenomenon that occurs when a body is exposed to an energy generating source that can produce a rise in temperature (42-45ºC) for a given time [1]. Specifically, the aim of the hyperthermia methods used in The Bioinstrumentation Laboratory is the development of thermal therapies, some of these using different kinds of nanoparticles, to kill cancer cells and reduce the damage on healthy tissues. The optical hyperthermia is based on noble metal nanoparticles and laser irradiation. This kind of nanoparticles has an immense potential associated to the development of therapies for cancer on account of their Surface Plasmon Resonance (SPR) enhanced light scattering and absorption. In a short period of time, the absorbed light is converted into localized heat, so we can take advantage of these characteristics to heat up tumor cells in order to obtain the cellular death [2]. In this case, the laboratory has an optical hyperthermia device based on a continuous wave laser used to kill glioblastoma cell lines (1321N1) in the presence of gold nanorods (Figure 1a). The wavelength of the laser light is 808 nm because the penetration of the light in the tissue is deeper in the Near Infrared Region. The first optical hyperthermia results show that the laser irradiation produces cellular death in the experimental samples of glioblastoma cell lines using gold nanorods but is not able to decrease the cellular viability of cancer cells in samples without the suitable nanorods (Figure 1b) [3]. The generation of magnetic hyperthermia is performed through changes of the magnetic induction in magnetic nanoparticles (MNPs) that are embedded in viscous medium. The Figure 2 shows a schematic design of the AC induction hyperthermia device in magnetic fluids. The equipment has been manufactured at The Bioinstrumentation Laboratory. The first block implies two steps: the signal selection with frequency manipulation option from 9 KHz to 2MHz, and a linear output up to 1500W. The second block is where magnetic field is generated ( 5mm, 10 turns). Finally, the third block is a software control where the user can establish initial parameters, and also shows the temperature response of MNPs due to the magnetic field applied [4-8]. The Bioinstrumentation Laboratory in collaboration with the Mexican company MRI-DT have recently implemented a new research line on Nuclear Magnetic Resonance Hyperthermia, which is sustained on the patent US 7,423,429B2 owned by this company. This investigation is based on the use of clinical MRI equipment not only for diagnosis but for therapy [9]. This idea consists of two main facts: Magnetic Resonance Imaging can cause focal heating [10], and the differentiation in resonant frequency between healthy and cancer cells [11]. To produce only heating in cancer cells when the whole body is irradiated, it is necessary to determine the specific resonant frequency of the target, using the information contained in the spectra of the area of interest. Then, special RF pulse sequence is applied to produce fast excitation and relaxation mechanism that generates temperature increase of the tumor, causing cellular death or metabolism malfunction that stops cellular division

Caracterización de colectores para sistemas de concentración fotovoltaica

Este proyecto, titulado “Caracterización de colectores para concentración fotovoltaica”, consiste en una aplicación en Labview para obtener las características de los elementos ópticos utilizados en sistemas de concentración fotovoltaica , atendiendo a la distribución espacial del foco de luz concentrado que generan. Un sistema de concentración fotovoltaica utiliza un sistema óptico para transmitir la radiación luminosa a la célula solar aumentando la densidad de potencia luminosa. Estos sistemas ópticos están formados por espejos o lentes para recoger la radiación incidente en ellos y concentrar el haz de luz en una superficie mucho menor. De esta manera se puede reducir el área de material semiconductor necesario, lo que conlleva una importante reducción del coste del sistema. Se pueden distinguir diferentes sistemas de concentración dependiendo de la óptica que emplee, la estructura del receptor o el rango de concentración. Sin embargo, ya que el objetivo es analizar la distribución espacial, diferenciaremos dos tipos de concentradores dependiendo de la geometría que presenta el foco de luz. El concentrador lineal o cilíndrico que enfoca sobre una línea, y el concentrador de foco puntual o circular que enfoca la luz sobre un punto. Debido a esta diferencia el análisis en ambos casos se realizará de forma distinta. El análisis se realiza procesando una imagen del foco tomada en el lugar del receptor, este método se llama LS-CCD (Difusión de luz y captura con CCD). Puede utilizarse en varios montajes dependiendo si se capta la imagen por reflexión o por transmisión en el receptor. En algunos montajes no es posible captar la imagen perpendicular al receptor por lo que la aplicación realizará un ajuste de perspectiva para obtener el foco con su forma original. La imagen del foco ofrece información detallada acerca de la uniformidad del foco mediante el mapa de superficie, que es una representación en 3D de la imagen pero que resulta poco manejable. Una representación más sencilla y útil es la que ofrecen los llamados “perfiles de intensidad”. El perfil de intensidad o distribución de la irradiancia que representa la distribución de la luz para cada distancia al centro, y el perfil acumulado o irradiancia acumulada que representa la luz contenida en relación también al centro. Las representaciones de estos perfiles en el caso de un concentrador lineal y otro circular son distintas debido a su diferente geometría. Mientras que para un foco lineal se expresa el perfil en función de la semi-anchura del receptor, para uno circular se expresa en función del radio. En cualquiera de los casos ofrecen información sobre la uniformidad y el tamaño del foco de luz necesarios para diseñar el receptor. El objetivo de este proyecto es la creación de una aplicación software que realice el procesado y análisis de las imágenes obtenidas del foco de luz de los sistemas ópticos a caracterizar. La aplicación tiene una interfaz sencilla e intuitiva para que pueda ser empleada por cualquier usuario. Los recursos necesarios para realizar el proyecto son: un PC con sistema operativo Windows, el software Labview 8.6 Professional Edition y los módulos NI Vision Development Module (para trabajar con imágenes) y NI Report Generation Toolkit (para realizar reportes y guardar datos de la aplicación). ABSTRACT This project, called “Characterization of collectors for concentration photovoltaic systems”, consists in a Labview application to obtain the characteristics of the optical elements used in photovoltaic concentrator, taking into account the spatial distribution of concentrated light source generated. A concentrator photovoltaic system uses an optical system to transmit light radiation to the solar cell by increasing the light power density. This optical system are formed by mirrors or lenses to collect the radiation incident on them and focus the beam of light in a much smaller surface area. In this way you can reduce the area of semiconductor material needed, which implies a significant reduction in system cost. There are different concentration systems depending on the optics used, receptor structure or concentration range. However, as the aim is to analyze the spatial distribution, distinguish between two types of concentrators depending on the geometry that has the light focus. The linear or cylindrical concentrator that focused on a line, and the circular concentrator that focused light onto a point. Because this difference in both cases the analysis will be carried out differently. The analysis is performed by processing a focus image taken at the receiver site, this method is called “LS-CCD” (Light Scattering and CCD recording). Can be used in several mountings depending on whether the image is captured by reflection or transmission on the receiver. In some mountings it is not possible to capture the image perpendicular to the receivers so that the application makes an adjustment of perspective to get the focus to its original shape. The focus image provides detail information about the uniformity of focus through the surface map, which is a 3D image representation but it is unwieldy. A simple and useful representation is provided by so called “intensity profiles”. The intensity profile or irradiance distribution which represents the distribution of light to each distance to the center. The accumulated profile or accumulated irradiance that represents the cumulative light contained in relation also to the center. The representation of these profiles in the case of a linear and a circular concentrator are different due to their distinct geometry. While for a line focus profile is expressed in terms of semi-width of the receiver, for a circular concentrator is expressed in terms of radius. In either case provides information about the uniformity and size of focus needed to design the receiver. The objective of this project is the creation of a software application to perform processing and analysis of images obtained from light source of optical systems to characterize.The application has a simple and a intuitive interface so it can be used for any users. The resources required for the project are: a PC with Windows operating system, LabVIEW 8.6 Professional Edition and the modules NI Vision Development Module (for working with images) and NI Report Generation Toolkit (for reports and store application data .)

Models for Internal Quality Fruit Sorting, Based on Time- Domain Laser Reflectance Spectroscopy (TDRS)

Time domain laser reflectance spectroscopy (TDRS) was applied for the first time to evaluate internal fruit quality. This technique, known in medicine-related knowledge areas, has not been used before in agricultural or food research. It allows the simultaneous non-destructive measuring of two optical characteristics of the tissues: light scattering and absorption. Models to measure firmness, sugar & acid contents in kiwifruit, tomato, apple, peach, nectarine and other fruits were built using sequential statistical techniques: principal component analysis, multiple stepwise linear regression, clustering and discriminant analysis. Consistent correlations were established between the two parameters measured with TDRS, i.e. absorption & transport scattering coefficients, with chemical constituents (sugars and acids) and firmness, respectively. Classification models were built to sort fruits into three quality grades, according to their firmness, soluble solids and acidity.

Super-resolution for a point source using positive refraction

Leonhardt demonstrated (2009) that the 2D Maxwell Fish Eye lens (MFE) can focus perfectly 2D Helmholtz waves of arbitrary frequency, i.e., it can transport perfectly an outward (monopole) 2D Helmholtz wave field, generated by a point source, towards a receptor called "perfect drain" (PD) located at the corresponding MFE image point. The PD has the property of absorbing the complete radiation without radiation or scattering and it has been claimed as necessary to obtain super-resolution (SR) in the MFE. However, a prototype using a "drain" different from the PD has shown λ/5 resolution for microwave frequencies (Ma et al, 2010). Recently, the SR properties of a device equivalent to the MFE, called the Spherical Geodesic Waveguide (SGW) (Miñano et al, 2012) have been analyzed. The reported results show resolution up to λ /3000, for the SGW loaded with the perfect drain, and up to λ /500 f for the SGW without perfect drain. The perfect drain was realized as a coaxial probe loaded with properly calculated impedance. The SGW provides SR only in a narrow band of frequencies close to the resonance Schumann frequencies. Here we analyze the SGW loaded with a small "perfect drain region" (González et al, 2011). This drain is designed as a region made of a material with complex permittivity. The comparative results show that there is no significant difference in the SR properties for both perfect drain designs.

Nonlocal electron heat-flux

Electron thermal conduction in a not quite collisional unmagnetlzed plasma is analysed. The failure of classical results for temperature scale-length up to 100 times larger than thermal mean-free-path for electron scattering, and large ion-charge number Z , is discussed. Recent results from a nonlocal model of conduction at large Z are reviewed. Closed form expressions for Braginskii's coefficients a ,/3 , y for Z =0(1) are derived. An extension of the nonlocal model for Z =0(1) is discussed.

Propiedades de materiales mediante análisis de radiación aleatoria

Las técnicas de speckle tienen un gran interés científico e ingenieril, ya que son métodos de ejecución rápida y no destructiva, con base en el análisis de las fluctuaciones de intensidad de la radiación producida cuando la luz coherente de un haz láser es esparcida por un material dado. En este caso se produce un patrón aleatorio de interferencia y difracción donde la suma de las componentes desfasadas dará lugar a máximos y mínimos de intensidad en distintos puntos del espacio. Éste, pese a tratarse de un ruido nocivo en multitud de áreas tales como la transmisión de señales o la holografía, tiene importantes propiedades físicas que lo caracterizan y lo hacen útil como medio para analizar sistemas reales de muy diversa índole. En el presente estudio, se ha llevado a cabo un análisis polarimétrico de la radiación aleatoria esparcida por una serie de muestras metálicas y dieléctricas con el objetivo de establecer una base comparativa que nos permita poder distinguir unas de otras. Para este fin se han comparado los parámetros de polarización de Stokes, el grado de polarización de la luz, las distribuciones de intensidad y el tamaño medio del speckle registrado en los distintos patrones de intensidad. Además, se analizará la dependencia de la rugosidad en el grado de polarización de la luz para los distintos medios sometidos a estudio. Abstract Speckle techniques have a great scientific and engineering interest as they are methods of rapid and non-destructive execution, based on the analysis of the fluctuations of intensity of the radiation produced when coherent light of a laser beam is scattered by a material given. In this case, a random pattern of interference and diffraction occurs where the sum of phase shifted components will result in maximum or minimum of intensity at different points in space. This, despite being a harmful noise in many areas such as signal transmission or holography, has important physical properties that characterize it and make it useful as a means to analyze real systems of various kinds. In the present study, we have conducted a polarimetric analysis of the random radiation scattered by a series of metal and dielectric samples in order to establish a comparative basis to allow us to distinguish one from another. To this end we have compared, the stokes polarization parameters, the degree of polarization (DOP), the intensity distributions and the average size of the speckle registered in the different intensity patterns. Furthermore, dependence of roughness in the DOP of light for the different means under study will be analyzed.

Country reports. Spain

Many diversified activities can be reported from the Spanish INHIGEO group. The International Year of Crystallography was celebrated on St. Albertus Magnus Day (January 28) at the National University of Distance Education at (Madrid). The scientist Santiago Garcia Granda, President of the European Association of Crystallography, was commissioned to present a lecture titled, Crystals and diffraction: 100 years of scientific milestones. An exhibition of minerals was held at the Madrid Mining School (November 24-29).