“Helliwell achieves a rare clarity. For instance, the derivation of the standard kinematic results starting from Einstein's postulates is outstandingly clear. Throughout he shows an unusual and sympathetic appreciation of the problems that are faced by the beginning student.”
—John Taylor, University of Colorado
“Special Relativity is definitely much better than the books I have read on this topic, and I would recommend it to any instructor who plans to teach a course on this topic. For anyone teaching special relativity as a part of a Modern Physics course, this book offers valuable supplementary reading.”
—Shirvel Stanislaus, Valparaiso University
We demonstrate the operation of a device that can produce chitosan nanoparticles in a tunable size range from 50–300 nm with small size dispersion. A piezoelectric oscillator operated at megahertz frequencies is used to aerosolize a solution containing dissolved chitosan. The solvent is then evaporated from the aerosolized droplets in a heat pipe, leaving monodisperse nanoparticles to be collected. The nanoparticle size is controlled both by the concentration of the dissolved polymer and by the size of the aerosol droplets that are created. Our device can be used with any polymer or polymer/therapeutic combination that can be prepared in a homogeneous solution and vaporized.
Absorption enhancement in thin metal-backed solar cells caused by dipole scatterers embedded in the absorbing layer is studied using a semi-analytical approach. The method accounts for changes in the radiation rate produced by layers above and below the dipole, and treats incoherently the subsequent scattering of light in guided modes from other dipoles. We find large absorption enhancements for strongly coupled dipoles, exceeding the ergodic limit in some configurations involving lossless dipoles. An antireflection-coated 100-nm layer of a-Si:H on Ag absorbs up to 87% of incident above-gap light. Thin layers of both strong and weak absorbers show similar strongly enhanced absorption.
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