Acidogenic bacteria within dental plaque biofilms are the causative agents of caries. Consequently, maintenance of a healthy oral environment with efficient biofilm removal strategies is important to limit caries, as well as halt progression to gingivitis and periodontitis. Recently, a novel cleaning device has been described using an ultrasonically activated stream (UAS) to generate a cavitation cloud of bubbles in a freely flowing water stream that has demonstrated the capacity to be effective at biofilm removal. In this study, UAS was evaluated for its ability to remove biofilms of the cariogenic pathogen Streptococcus mutans UA159, as well as Actinomyces naeslundii ATCC 12104 and Streptococcus oralis ATCC 9811, grown on machine-etched glass slides to generate a reproducible complex surface and artificial teeth from a typodont training model. Biofilm removal was assessed both visually and microscopically using high-speed videography, confocal scanning laser microscopy (CSLM), and scanning electron microscopy (SEM). Analysis by CSLM demonstrated a statistically significant 99.9% removal of S. mutans biofilms exposed to the UAS for 10 s, relative to both untreated control biofilms and biofilms exposed to the water stream alone without ultrasonic activation (P < 0.05). The water stream alone showed no statistically significant difference in removal compared with the untreated control (P = 0.24). High-speed videography demonstrated a rapid rate (151 mm(2) in 1 s) of biofilm removal. The UAS was also highly effective at S. mutans, A. naeslundii, and S. oralis biofilm removal from machine-etched glass and S. mutans from typodont surfaces with complex topography. Consequently, UAS technology represents a potentially effective method for biofilm removal and improved oral hygiene.
In this paper we present significant progress on the fabrication of small-core lead-silicate holey fibers. The glass used in this work is SF57, a commercially available, highly nonlinear Schott glass. We report the fabrication of small core SF57 fibers with a loss as low as 2.6 dB/m at 1550 nm, and the fabrication of fibers with a nonlinear coefficient as high as 640 W-1 km-1. We demonstrate the generation of Raman solitons at ~1550 nm in a short length of such a fiber which highlights the fact that the group velocity dispersion can be anomalous at these wavelengths despite the large normal material dispersion of the glass around 1550nm., "Four-wave mixing based 10-Gb/s tunable wavelength conversion using a holey fiber with a high SBS threshold," IEEE Photon. Technol. Lett. 15, 440-442 (2003).
Abstract-Biosensors are commonly produced using an SOI CMOS process and advanced lithography to define nanowires. In this work, a simpler and cheaper junctionless 3-mask process is investigated, which uses thin film technology to avoid the use of SOI wafers, in-situ doping to avoid the need for ion implantation and direct contact to a low doped polysilicon film to eliminate the requirement for heavily doped source/drain contacts. Furthermore, TiN is used to contact the biosensor source/drain because it is a hard, resilient material that allows the biosensor chip to be directly connected to a printed circuit board without wire bonding. pH sensing experiments, combined with device modelling, are used to investigate the effects of contact and series resistance on the biosensor performance, as this is a key issue when contacting directly to low doped silicon. It is shown that in-situ phosphorus doping concentrations in the range 4×10
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