Standardization of Rn-222 at the Australian Radiation Laboratory.

The standardization of Rn-222 at the Australian Radiation Laboratory involves the calibration of scintillation cells by two methods using standard Ra-226 solutions traceable to the National Institute of Standards and Technology. One of these methods, namely the injection method, involves direct transfer of Rn-222 into a scintillation cell. In the other method, known as the volumetric method, the Rn-222 is flushed into a large container and the scintillation cell calibrated by sampling from this container. A comparison of the two methods showed that similar results were obtained, with the overall random uncertainty being 3.4% for one standard deviation. Using better estimates of the true calibration factors, the overall random uncertainty was reduced to 1.8% for one standard deviation.

The use of broadband acoustic transducers and pulse-compression techniques for air-coupled ultrasonic imaging.

A pulse-compression technique has been applied to air-coupled testing of solid materials. Capacitance transducers were used to generate wide bandwidth swept-frequency (chirp) signals in air, which were then used to measure and image solid samples in through transmission. The results demonstrate that such signal processing techniques lead to an improvement in the signal to noise ratio and timing accuracy for air-coupled testing. Measurements of thickness and spectroscopic experiments are presented. Images of defects in a wide range of materials, including metals and carbon-fibre composites have also been obtained. This combination of capacitive transducers with pulse-compression techniques is shown to be a powerful tool for non-contact air-coupled ultrasonic measurements.

Air-coupled ultrasonic evaluation of food materials.

This research was performed with the aim of detecting foreign bodies and additives within food products, and to measure selected acoustic properties, without contact to the sample. This would allow use in manufacturing plants on production lines, where contacting the product for ultrasonic inspection would not be feasible. Images of internal structure are reported. The air-coupled system uses capacitive devices which are able to provide sufficient bandwidth for many measurements, including the detection of foreign bodies in cheese, the detection of deliberate additives to chocolate, the detection of fill level and content of metallic food cans, and measurements of frozen dough products. The approach demonstrates that ultrasound has the potential for application to many industrial food packaging environments where non-metallic objects within food need to be detected.

A near-infrared (NIR) technique for imaging food materials.

The results of imaging experiments in food materials are presented, using near-infrared wavelengths. The technique uses a modulated source and a lock-in amplifier detection circuit to give a high sensitivity to changes in through-transmission signal levels. This is shown to lead to a set of images, whereby the internal content of various foods can be imaged. Examples are presented of the detection of foreign bodies, both metallic and nonmetallic, to illustrate the imaging performance.

Selective detection of alkanolamine vapors by ion mobility spectrometry with ketone reagent gases.

The ion mobility (IMS) spectra of the alkanolamines, monoethanolamine (MEA), 3-amino-1-propanol (PRA), 4-amino-1-butanol (BUA), and 5-amino-1-pentanol (PEA) with acetone and 4-heptanone reagent gases have been measured using a hand-held spectrometer. Monomer and dimer peak patterns were observed for all the alkanolamines with acetone reagent gas. Drift times of monomer and dimer ion clusters for each alkanolamine increased linearly in order of size of alkyl group. Ammonia, Freon 22, and F76 diesel vapors, having similar or coincident mobilities, caused severe interference. Replacement of acetone with 4-heptanone reagent gas resulted in good separation by the altering drift times of product ions. The limit of detection was 0.005 ppm having a linear range of 0.005-0.7 ppm, and signal saturation occurred above 0.88 ppm. Detection was reversible, with a response time of 4 min and a slower recovery time of > 60 min, at vapor levels of 0.7 ppm and ambient nozzle and drift-region temperatures. In contrast to acetone chemistry, single-peak patterns were observed for the alkanolamines with the 4-heptanone reagent. Further, drift times unexpectedly remained stagnant with increasing alkyl-group size. From atmospheric pressure chemical ionization (APcI) tandem mass spectral identifications and collision induced studies, dynamic changes in product-ion equilibria in the IMS drift region compensated by differences in collision cross sections were suggested as the governing causes of the unusual mobility effect.

[Tumor of the glomus caroticum, diagnosed by intravenous digital subtraction angiography]. / Tumor des Glomus caroticum, durch intravenös-digitale Subtraktionsangiographie diagnostiziert.

Digital video subtraction angiography is a valuable method for the diagnosis of the relatively rare glomus caroticum tumour. This is shown at one case and proved with conventional angiography of the carotid artery and operation.