Scanning electron microscopy of Onchocerca sweetae

Holdsworth P.A. 1988. Scanning electron microscopy of Onchocerca sweetae. International Journal for Parasitology 18: 561-563. Scanning electron microscopy of adult Onchocerca sweetae highlighted the distinctive cuticular ridges of the midbody region of female worms, the cuticular annulations of males and females, and the crescent-shaped and prominent anus on the ventral surface of female worms. Study of male specimens revealed uniform annulations of the worm body, caudal papillae and spicules. The cephalic regions of male and female specimens revealed features of little value for differentiation from other nodule-inducing species of Onchocerca

Near-infrared diode laser in situ monitoring and control of chemical vapour deposition processes

The objective of the experiments described here was to demonstrate the application of a relatively new technique, near-IR diode laser absorption spectroscopy (NIRDLAS), to the monitoring and control of chemical vapour deposition processes. The technique is entirely non-invasive and detects gas phase species in an in situ manner with a time resolution of the order of milliseconds. Approach. In this illustration of the technique, the atmospheric pressure MOCVD reaction of tin oxide deposition on a glass substrate was studied. The precursors were dimethyl tin dichloride (DMT), water and oxygen with a substrate temperature of 650 °C. Methane was selected as the product species to monitor. The high spectral resolution of the laser allows unambiguous, selective detection of methane in the 2n3 band around 1665 nm. The high spatial resolution of the beam and the ability of the beam to pass directly through the walls of a quartz reactor leads to the possibility of spatial monitoring of reactors. By measuring the ratio of absorption lines arising from different vibration or rotation states it is also possible to extract temperature information across the reactor. Although not as sensitive as mid-infrared diode laser spectroscopy, the technique has many practical advantages, for example, fibre optics can also be used to launch and receive the beam. Results It was shown that the evolved methane concentration was directly correlated with the deposition rate of the tin oxide film. This important result enables the monitoring of thin film production and properties in situ during production. Preliminary results will also be presented of near-infrared laser reflectance measurements taken during the deposition of InP films by APCVD. Conclusions The technique is generic and can be applied to in situ monitoring of gas phase CVD, PVD and PECVD reactions either for diagnostic purposes or for process control

Time-Resolved In-Situ Spectroscopic Monitoring of the CVD of Tin Oxide onto a Glass Substrate

Near-infrared diode laser absorption spectroscopy has been demonstrated as an in-situ, non-invasive probe for use with a CVD reactor. The technique has been applied to the CVD of tin oxide onto a glass substrate, and by monitoring the evolution of methane in the reactor, it has been shown that the concentration of methane is correlated with the deposition rate of the tin oxide film. This illustrates the powerful possibilities for monitoring thin film production and properties, in-situ, during deposition