Thin film bulk acoustic wave filter

Thin film bulk acoustic wave (BAW) resonators (FBAR) are fabricated on a silicon nitride bridge using a ZnO piezolayer on a glass substrate and surface micromachining by standard thin film technology. These resonators exhibit a coupling constant k/sub t//sup 2/=7.8% at the first thickness extensional wave mode and are used as impedance elements in a ladder filter in the 1-GHz frequency band of mobile telecommunications. An electrical equivalent circuit is used to characterize the properties of the resonators and to show how the performance of the filter depends on the parameters of the resonators. 2.5% bandwidth, 2.8-dB insertion loss, and 35-dB selectivity are obtained in a filter with six resonators. The technology can be used to manufacture miniature microwave filters without any additional inductances.     

Mechanical properties of individual fiber segments of electrospun lignocellulose‐reinforced poly(vinyl alcohol)

The influence of lignocellulosic nanofibers (LCNF) additive on the inherent mechanical properties of submicron electrospun poly(vinyl alcohol) (PVA) fibers is reported. LCNF with a diameter of 25 ± 15 nm and a length of 220 ± 90 nm obtained from hemp shives were dispersed in aqueous PVA solutions to produce homogeneous nanocomposite fibers with 0, 5, and 10 w/w % LCNF loads in solid PVA. Tensile tests on mats show that LCNF additive causes up to sevenfold increase in stiffness and significant decrease in elongation at yield. AFM‐based 3‐point bending tests on single LCNF‐doped fibers reveal up to 11.4 GPa Young's modulus in the diameter range of 300 to 500 nm, indicating a 2.4 times increase compared to neat PVA fibers. Mechanical properties of both neat and LCNF‐doped PVA fibers are found to be strongly size‐dependent at lower fiber diameters, with Young's modulus values exceeding 100 GPa at below 100 nm diameters. The results can be explained by extensive restructuration of hydrogen bonding network due to the LCNF additive. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44361.     

Purification of titania nanoparticle thin films: Triviality or a challenge?

Although purification of titania nanoparticles is a very common process in laboratory practice the specific purification protocol is often chosen without scientific justification. In the present work the efficiency of three different and in laboratory practice widely used treatments is compared for removing organic contaminants from the surface of titania nanoparticles. The most effective purification treatment was annealing of nanoparticles below 400 °C: annealing at higher temperatures causes besides purification the growth of nanoparticles.     

Direct measurement of tissue blood flow and metabolism with diffuse optics

Diffuse optics has proven useful for quantitative assessment of tissue oxy- and deoxyhaemoglobin concentrations and, more recently, for measurement of microvascular blood flow. In this paper, we focus on the flow monitoring technique: diffuse correlation spectroscopy (DCS). Representative clinical and pre-clinical studies from our laboratory illustrate the potential of DCS. Validation of DCS blood flow indices in human brain and muscle is presented. Comparison of DCS with arterial spin-labelled MRI, xenon-CT and Doppler ultrasound shows good agreement (0.50相似文献