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Biomedical subjects

D G Howitt

Publications and source records attributed to D G Howitt.

5 recordsLinked to original sources

Microinstrument gradient-force optical trap.

A micromachined fiber-optic trap is presented. The trap consists of four single-mode, 1064-nm optical intersection. The beam fibers mounted in a micromachined silicon and glass housing. Micromachining provides the necessary precision to align the four optical fibers so that the outputs have a common intersection forms a strong three-dimensional gradient-force trap with trapping forces comparable with that of optical tweezers. Characterization of the multibeam fiber trap is illustrated for capture of polystyrene microspheres, computer simulations of the trap stiffness, and experimental determination of the trapping forces.

Computer Simulation↗

The difficulties with low-level asbestos exposure assessments in public, commercial, and industrial buildings.

A method by which the airborne concentration of asbestos, low enough to substantiate that a significant health risk does not exist, is presented. The method is different from that used for the determination of occupational exposure, which is shown to be inadequate in this concentration range and a justification of how this alternative procedure might be used to achieve compliance is put forward. The difficulties associated with both the physical measurement and the significance of the concentrations that are determined are discussed.

Air↗

A novel technique for the preparation of thin films for cross-sectional transmission electron microscopy.

A method is described for the preparation of cross-sectional samples of thin films for transmission electron microscopy. The technique produces larger amounts of thin region as compared with ion milling and eliminates the problems associated with ion beam damage. The requirement is that the films or multilayers must initially be deposited on a water-soluble substrate such as single-crystal NaCl.

Microscopy, Electron↗