Abstract: A canvas tensioning frame corner having adjoining stretcher bar ends; each stretcher bar end having a tapered expanding groove from the inside of the corner to the tip of the corner; a corner embedment nested in the grooves; the corner embedment having tapered edges matching the grooves; wherein a movement of the corner embedment inward away from the tip of the corner urges the stretcher bars apart to stretch the canvas affixed to each stretcher bar, side and corner; a corner embedment brace attached across the corner to support a bolt attached to the corner embedment; and wherein a wing nut attached to the bolt urges the corner embedment toward the brace.

Abstract: A method of particle detection includes optically trapping a single particle having an averaged linear dimension of between 0.10 microns and 50 microns in a focal region optical trap formed from a trap visible to near-infrared wavelength. The trap is proximal to a substrate having a discontinuous metal coating so as to exploit a surface plasmon resonance generated electric field caused by irradiation of the metal coating. The single particle is then exposed to an interrogation wavelength to yield scattering spectrum relating to the particle. A particle identification digital database containing scattering spectra from a variety of different single particles that vary in spectral features facilitates identification of unknown spectra. A microfluidic cell is detailed to facilitate the automated scanning of numerous particles from a sample.

Abstract: A single particle photoacoustic absorption spectrometer for directly measuring the absorption spectra for in situ individual aerosol type particles that is comprised of an electrodynamic trap capable of suspending a charged particle in free-space in a non-intrusive manner; a source of modulated monochromatic electromagnetic radiation, e.g., a laser, and an acoustic transducer/resonator for detecting/amplifying sound waves emitted by the irradiated particle. Depending on the characteristics of the particle, a certain fraction of the electromagnetic energy will be absorbed by the particle resulting in its rapid heating and cooling at the modulation frequency. The heat generated within the particle is rapidly transferred to the surrounding air resulting in a sound wave. The intensity of the sound wave is proportional the absorbed energy by the particle.