Flexible microwave absorbers based on barium hexaferrite, carbon black, and nitrile rubber for 2–12 GHz applications

Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2–12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding 20 dB is obtained for all the samples in a wide frequency range of 2–12 GHz when an appropriate absorber thickness between 5 and 9mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties,

Microwave Absorption of Nylon 6,6 Based Polymer Ferrite Composites

Ferrite composites are magnetic composites consisting of fine particles of metal ferrites dispersed in the polymer matrix. These composites have a variety of applications as flexible magnets, pressure/photo sensors and microwave absorbers. Polymers and magnetic materials play a very important role in our day to day life. Both natural and synthetic polymers are today indispensable to mankind. The polymers, which include rubber, plastics and fibers, make life easier and more comfortable.

Microwave exfoliated reduced graphene oxide epoxy nanocomposites for high performance applications

Graphene has captured the attention of scientific community due to recently emerging high performance applications. Hence, studying its reinforcing effects on epoxy resin is a significant step. In this study, microwave exfoliated reduced graphene oxide (MERGO) was prepared from natural graphite for subsequent fabrication of epoxy nanocomposites using triethylenetetramine (TETA) as a curing agent via insitu polymerization. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), C13 NMR spectroscopy, X-ray photoelectron spectroscopy (XPS) and ultravioletevisible (UVevis) spectroscopy were employed to confirm the simultaneous reduction and exfoliation of graphene oxide. The reinforcing effect of MERGO on epoxy resin was explored by investigating its static mechanical properties and dynamic mechanical analysis (DMA) at MERGO loadings of 0 to 0.5 phr. The micro-structure of epoxy/MERGO nanocomposites was investigated using scanning electron microscope (SEM), transmission electron microscope (TEM) and XRD techniques. The present work reports an enhancement of 32%, 103% and 85% in tensile, impact and flexural strength respectively of epoxy by the addition of even 0.25 phr MERGO. At this loading elastic and flexural moduli also increased by 10% and 65%, respectively. Single-edge-notch three-point-Bending (SEN-TPB) fracture toughness (KIC) measurements were carried out where a 63% increase was observed by the introduction of 0.25 phr MERGO. The interfacial interactions brought about by graphene also benefited the dynamic mechanical properties to a large extent in the form of a significant enhancement in storage modulus and slightly improved glass transition temperature. Considerable improvements were also detected in dielectric properties. The epoxy nanocomposite also attained an ac conductivity of 10 5 S/m and a remarkable increase in dielectric constant. The simple and cost effective way of graphene synthesis for the fabrication of epoxy/MERGO nanocomposites may be extended to the preparation of other MERGO based polymer nanocomposites. This remarkable class of materials has thrown open enormous opportunities for developing conductive adhesives and in microelectronics

Investigations on Metamaterial Based Spiral Inductors for Compact Microwave Devices

Division of Electronics Engineering

The Li-like KLL-Auger spectrum of foil excitation Ne-projectiles

KLL-Auger transitions of the three electron system in Ne have been recorded in a coincidence experiment frec of contaminants from other systems. Energies as well as intensities are compared with calculated values.

The Spectrum of knowledge - starting off

A few files for background reading

Can children with autism spectrum disorders be helped to acquire a theory of mind?. '¿Se puede ayudar a los niños con trastornos del espectro autista a adquirir una teoría de la mente?'.

Resumen en español

Language therapy results with children of the autism spectrum. 'Resultados de terapia de lenguaje con niños del espectro autista'.

Resumen en español. Resumen basado en el de la publicación

100 ideas for supporting pupils on the autistic spectrum.

Guía que proporciona a los que trabajan con niños autistas mayores de cinco años cien ideas de cómo apoyar y desarrollar su aprendizaje. Las ideas van desde el desarrollo de la comprensión de los alumnos a las habilidades de comunicación para garantizar que estén bien en su entorno de aprendizaje.

The teaching assistant's guide to autistic spectrum disorders.

Guía práctica para comprender el efecto que el autismo tiene tanto en la vida de los niños como en la de sus familias y la mejor manera de apoyarlos. Muestra cómo desarrollar estrategias para la integración de estos niños en la escuela, producir técnicas de gestión de un comportamiento eficaz y crear métodos para el éxito en la enseñanza y en el aprendizaje. Cada capítulo ofrece una gama de actividades y estudios de casos reales que ayuda a consolidar el aprendizaje.

Reaching and teaching the child with autism spectrum disorder : using learning preferences and strengths.

Manual que ofrece un enfoque positivo a la comprensión y la educación de los niños con autismo. Ofrece una mayor comprensión de la perspectiva y el comportamiento de un niño con autismo y explora cómo pueden utilizarse sus preferencias de aprendizaje, fortalezas e intereses para facilitar el aprendizaje y aumentar la motivación. La autora ha utilizado una mezcla de teorías de la personalidad, inteligencias múltiples y aprendizaje para crear un método de trabajo, Aprendizaje Preferencias y Fortalezas (LPS), para el desarrollo de habilidades de aprendizaje para la vida independiente en niños con autismo entre dos y doce años. Describe los principios básicos, preferencias de aprendizaje y los puntos fuertes típicos de los niños con autismo y ofrece una estructura de programa detallado, pero flexible, basada en estos conceptos. Fácil de seguir, se describen en cada capítulo actividades y orientaciones junto con ejemplos e ilustraciones.

Autistic spectrum disorders : practical strategies for teachers and other professionals.

El espectro autista, a veces también se conoce como trastorno generalizado del desarrollo, se caracteriza por presentar la persona déficit en la interacción social, la comunicación y en la restricción de actividades e intereses. Se han identificado seis áreas principales en las que los niños con este trastorno tienen más dificultad en las escuelas: comportamiento, aprendizaje y pensamiento, conversación, experiencias sensoriales y motoras, lenguaje y comunicación y habilidades sociales. Este manual ofrece ayuda a los adultos interesados en identificar, comprender la razón de esta conducta particular y da consejos prácticos para cambiar, moderar o administrar estas dificultades dentro de escuelas normales. Tiene recursos fotocopiables.