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The core-logger has been designed for the high-resolution radiometric analysis of soil cores using multiple detectors. This device allows for the automation of the measuring process and eliminates the need to dissect the cores. The design is aimed at measuring soil-cores with a 10cm radius and a length of 1m and allows for up to 4 detectors to be mounted on the measuring platform. Currently a combination of Bismuth-German.te (BGO) and C.esiwn-Iodide (CsI) detectors are used. The core logger required a good spatial resolution of - 1 cm. This has been difficult to obtain and has required extensive investigation. The shielding configurations were varied and the effect of background radiation was looked at in detail to determine an optimal construction. A secondary objective has been the complete measurement of a single core in 24 hours. This has also been difficult to achieve because the low activity of natural radiation in the core samples needs longer measuring times. The BGO detectors were used as a more efficient detector (than, e.g. CsI) which helped to reduce the required measuring time. Measured spectra have been analysed to determine the activity concentrations of the specific radionuclides of interest: 232Th, 238U, 40K and 137Cs. These activity profiles of the measured cores provide information that can then be used to radiometrically fingerprint the sample to determine soil characteristics such as grain size and mineral content. However, because the actual resolution of the system ( ~3cm) is greater than the typical core slice (~ 2cm), the radiometric information in a specific core-slice contains contributions from its adjacent slices. This folding or convolution of the measured spectra can be undone using a deconvolution method. which was examined and commented on. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 132-135).

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references (leaves 167-176). Also available via World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Aug 12.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 112-118). Also available on the Internet.

Almost a century has elapsed since the antigen-antibody interaction was first recognised as the basis of an immune response (Ehrlich, 1897). However, it was only in the 1930s, with the development of improved technologies that this concept was better understood, and led to the discovery of the amazing diversity and specificity of antibody molecules (Landsteiner, 1933). Theoretically, it is possible to make antibodies to a variety of biological substances and other chemicals, and therefore they are ideally suited as specific recognition elements to be used for analytical, cytological, functional, therapeutic and biochemical purposes. The development of the radioimmunoassay (RIA) thirty five years ago, revolutionised research in many areas of clinical and scientific investigation. This technique evolved rapidly from the discovery made by Berson et al. in 1956 that antibodies to insulin could be detected in patients treated with this hormone, by measuring the binding of radiolabeled insulin to these antibodies. Although in the past RIAs have been the most important assay system employing antibody and labelled tracer, the limitation was that reliance had to be placed on the chance development of a good polyclonal antibody. These shortcomings stimulated the search for monospecific antibodies of reproducible quality and sufficient quantity. The development and introduction of monoclonal antibody technology brought about a revolution in immune serology (Kohler and Milstein, 1975). Establishment of immortal cell lines which contained the genetic elements of antibody-producing cells was achieved by fusion between a myeloma cell line and spleen cells from an immunised donor. The resulting hybrids had the essential properties of both parents, namely, permanent growth and a high capacity for the synthesis and secretion of immunoglobulins, normally characteristics of plasmacytomas, together with the genetic elements defining a specific antibody. Gestational trophoblastic disease (GTD) is a neoplastic condition of the trophoblast and occurs as molar pregnancy in a benign or invasive form, or as choriocarcinoma in a malignant form. Effective therapy has been developed for the treatment of both choriocarcinoma and molar pregnancy, but the key to successful management of these patients lies in their prompt diagnosis and careful monitoring of response to treatment (Green-Thompson, 1986). Fortuitously, these tumours elaborate the human chorionic gonadotrophin hormone (hCG) and its free alpha (a) and beta (B) subunits and hence a ready marker for the tumour exists. Human chorionic gonadotrophin is one of a group of glycoprotein hormones, which includes luteinising hormone (LH), follicle stimulating hormone (FSH) and thyroid stimulating hormone (TSH). These hormones are composed of two dissimilar subunits designated a and B, which are bound non-covalently in the intact molecule. The B-subunit of each glycoprotein hormone is unique and is responsible for the respective biological and immunological properties of the glycoproteins. In contrast, all four hormones possess an identical a-subunit which is coded for by a single gene (Fiddes and Goodman, 1979). The measurement of hCG and its free B-subunit, as so-called BhCG, for the diagnosis and monitoring of therapy in patients with GTD is now routinely practised throughout the world (Vaitukaitis et al., 1972). However it has been demonstrated by Bagshawe (1975) that when serum BhCG can no longer be measured by current RIA methods, up to 10" tumour cells may remain undetected. In addition, there have been isolated reports of two patients with choriocarcinoma in whom BhCG was undetectable in the serum but who appeared to be secreting only the a-subunit (Dawood et al, 1977). Furthermore, it has been suggested that measurement of free a-subunit rather than intact hCG or the free B-subunit is a more effective means of detecting persistent trophoblastic disease as well as tumour recurrence following treatment (Quigley et al, 1980a and b). Radioimmunoassays which measure the free a-subunit of hCG have been developed, but in general lack the specificity and sensitivity required (Gaspard et al, 1980; Kohorn et al, 1981). These assays employ polyclonal antisera which also detect epitopes common to the pituitary gonadotrophins. Thus there is a need to produce monoclonal antibodies which recognise regions of the free a-subunit which are hidden in the intact gonadotrophins. Such antibodies would provide the required specificity for use in RIAs but are limited in their use by their inherent lack of high affinity for the antigen. Fortunately, this drawback may be overcome by using monoclonal antibodies as labelled reagents in an alternative assay system, the immunoradiometric assay (IRMA), described by Miles and Hales (1968). The IRMA, particularly the two-site sandwich version of the assay, has been shown to provide greater sensitivity in addition to allowing enhanced specificity. This is a consequence of the use of two antibodies in excess to detect the analyte, each directed at a different epitope on the target molecule. The first antibody, referred to as the capture antibody, is usually linked to a solid-phase to facilitate easy separation and is added in excess relative to the target hormone to enhance antibody-antigen interaction, thereby allowing increased sensitivity in the measurement of analyte. The second antibody, referred to as the detection antibody, is labelled with a radioactive isotope or an enzyme to detect antigen already bound to the capture antibody. The application of monoclonal antibodies specific for the free a-subunit to a highly sensitive IRMA format is an obvious need. Hence this study was undertaken firstly, to raise and characterise monoclonal antibodies to the free a-subunit, secondly to develop an IRMA using these antibodies and finally to establish whether measurement of free a-subunit has any clinical advantage. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1990.

Kwong Lop Sam. / Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 60-63.

High-energy ion beam based proton induced x-ray (PIXE) is an ideal analytical tool suitable for simultaneous quantification of trace elements with high accuracy. The quantification of trace elements in solids using PIXE has been well established for over two decades. The main objective of this study is to extend this capability to solids with an inhomogeneous internal structure. In this study, pure GAC and PAC samples were soaked in known concentration of arsenic (As) solution and the trace amount of As uptake was determined during these exposures using PIXE, neutron activation analysis (NAA) and atomic absorption spectroscopy (AAS). There is a good agreement between the values and adsorption mechanisms derived from the NAA and pelletised PIXE measurements and some AAS measurements. Micro-PIXE was used to understand the discrepancies in the As adsorption on the pore and flat surfaces of GAC samples. / Master of Science (Hons) (Physics)

14.8-MeV neutrons from a Cockcroft-Walton type accelerator/neutron generator have been used to irradiate particulate and ionic samples prepared from river water. Five-minute irradiations were performed in a flux of order 109 neutrons/cm2/sec at target position. Gamma-ray spectra resulting from the activated products were recorded with a spectrometer system consisting of a high resolution Ge(Li) detector (2.5% efficiency at 1330 keV) and multichannel analyzer. Trace elements present in the samples were identified by the characteristic gamma-ray energies and half lives associated with the decay products. Standards of known concentration were used to make relative determinations of the quantities of trace elements present in the water. Elements observed in samples with parts per million concentrations include Al, Ba, Ca, Cl, Cr, Fe, K, Mg, Na, Si, and Sr. Sensitivities for elements not observed in the water samples were also determined for As, Cd, Hg, Ni, Ti, Zn, and Zr.Ball State UniversityMuncie, IN 47306