Graphene-like metallic-on-silicon field effect transistor

In this manuscript, we present a field effect transistor with a channel consisting of a two-dimensional electron gas located at the interface between an ultrathin metallic film of Ni and a p-type Si(111) substrate. We have demonstrated that the two-dimensional electron gas channel is modulated by the gate voltage. The dependence of the drain current on the drain voltage has no saturation region, similar to a field effect transistor based on graphene. However, the transport in this transistor is not ambipolar, as in graphene, but unipolar

High performance thin film bulk acoustic resonator covered with carbon nanotubes

This letter presents experimental results concerning a thin film bulk acoustic wave resonator realized on a thin GaN membrane and covered with a thin film of double walled carbon nanotube mixture. The quality factor was measured before and after the coating of the resonator with the nanotube thin film. The quality factor has increased more than ten times when the resonator was coated with nanotubes, due to their high elasticity modulus and low density, which confers a much higher acoustic impedance of the resonator electrodes and thus confines much better the longitudinal acoustic standing waves inside the resonator

Comprobación de la presencia de probióticos en productos de uso oral

El objetivo principal de esta investigación fue comprobar la presencia de probióticos en productos de uso oral, comercializados en las diferentes farmacias ubicadas en la Colonia Médica de San Salvador, en las presentaciones de cápsulas, comprimidos masticables y sobres. Para la recolección de la muestra se utilizó una hoja de cotejo, que se aplicó para la identificación de los probióticos comercializados en cada una de las 16 farmacias en estudio, obteniendo un total de 24 muestras. Se realizó una descripción de cada uno de los productos con la normativa de etiquetado Reglamento Técnico Centroamericano RTCA 11.01.02:04 Productos Farmacéuticos. Etiquetado de Productos Farmacéuticos para uso Humano. Así mismo un recuento en placa de bacterias ácido lácticas, también una identificación de los microrganismos tanto a nivel macroscópico como microscópico de las presentaciones de cápsulas, comprimidos masticables y sobres, se comparó con el estándar de referencia Lactobacillus rhamnosus. Obteniéndose los siguientes resultados: para las muestras de cápsulas su crecimiento en placa fue de 1.5x103 UFC/mL, las de comprimidos masticables su crecimiento fue de 1.3x103 UFC/mL y las de sobres de 1.9x103 UFC/mL. En las tres presentaciones el crecimiento en placa fue inferior al rango que establece la Organización de las Naciones Unidas para la Agricultura y la Organización Mundial de la Salud (FAO/OMS) de 106 a 109 UFC. Para ser considerado como probiótico y ejercer un efecto positivo para el consumidor. Se recomiendan nuevas investigaciones con diferentes marcas y presentaciones de probióticos, para poder confirmar si contiene la cantidad que especifica en los productos. La investigación de llevó a cabo en el Laboratorio de Microbiología del Centro de Investigaciones y Desarrollo en Salud (CENSALUD) de la Universidad de El Salvador, durante el periodo de 2017 al 2019

Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

AlN/diamond heterostructures are very promising for high frequency surface acoustic wave (SAW) resonators. In their design, the thickness of the piezoelectric film is one of the key parameters. On the other hand, the film material quality and, hence, the device performance, also depend on that thickness. In this work, polished microcrystalline diamond substrates have been used to deposit AlN films by reactive sputtering, from 150 nm up to 3 μm thick. A high degree of the c-axis orientation has been obtained in all cases. SAW one port resonators at high frequency have been fabricated on these films with a proper combination of the film thickness and transducer size

Experimental characterization of 38 GHz micromachined GaAs receiver

The experimental characterisation of a 38 GHz micromachined GaAs receiver is presented. The structure monolithically integrates a double-folded slot antenna and a Schottky diode on the same GaAs thin membrane. The measurements demonstrate that this approach has the potential for innovative circuit architecture development

Computer aided design of mm wave circuits fabricated on micromachined silicon

This paper presents the design methodology for the micromachined circuits operating in the microwave and mm-wave frequency region. The design is based on dividing the circuit into membrane-supported components, bulk components and membrane to bulk transitions. Every region is modeled using appropriate and techniques using full-wave electromagnetic simulation software. As illustrative examples, the design of band-pass filter structures and double-folded slot antenna arrays are briefly described. The micromachined structures were fabricated and measured results are presente