The main aims of this thesis were to establish whether an acute inflammatory response is provoked in rats by the subcutaneous administration of cadmium, and to evaluate the possible role that such a response might play in the alterations in metal homeostasis and the development of anaemia which accompanies the use of this model of cadmium intoxication. An intense local reaction to the subcutaneous administration of cadmium was found. Many of the systemic changes, most notably in haematological parameters and in levels of iron, copper and plasma proteins, mimicked those seen in the acute inflammatory response. Possible causes of the resultant anaemia are discussed and inflammation is implicated as a predominant factor in its development. The results suggest that many of the effects which in previously published work have been attributed to a direct interaction of cadmium with the system under investigation, may in fact be secondary consequences of cadmium-induced inflammation. Comparison of the effects of subcutaneous administration of cadmium and other selected metal salts with changes occurring in two recognised models of acute inflammation revealed marked differences in the local tissue reaction to different substances as well as in the magnitude of various components of the systemic response. The oedematous, necrotic and extensively destructive nature of the cadmium-induced lesion has been highlighted and shown to be partially alleviated by pre- and simultaneous treatment with zinc. Explanations for this protective phenomenon are offered, based on possible target sites of cadmium, particularly in terms of interaction with zinc-dependent processes. With a view to understanding the mechanisms involved in acute cadmium toxicity, luminol-amplified chemiluminescence, which is indicative of free radical formation and the production of reactive oxygen species, was measured directly from intact tissue samples. Inflamed tissue sampled from subcutaneous sites of cadmium administration emitted substantially more chemiluminescence than noninflamed tissue or tissue from sites to which other metals or turpentine was administered. It was demonstrated that intact tissue samples can also be used to assess free radical generation, as detected by chemiluminescence, during in vitro treatment. A pronounced dose-related response was seen with cadmium which could be inhibited by various pretreatment procedures, such as incubation with zinc or certain metal chelators. The significance of these results in relation to the mechanism of toxic action of cadmium as well as to the potential use of this chemiluminescence technique is discussed.

The Stability constants of some cadmium (II) ligand complexes have been measured by glass electrode potentiometry. These constants were used in computer model systems in order to assess the ligand's suitability as a cadmium sequestering agent in vivo. It is suggested that nitrogen and oxygen containing amino-acids complex zinc preferentially with respect to cadmium, and that the existing cadmium therapeutical, EDTA, is highly unspecific. Glutathionate is proposed as the most promising ligand for the treatment of cadmiumism. An investigation was undertaken to assess the reliability and accuracy of a solid state cadmium-ion selective electrode. A new system of metal buffers was introduced into the calibration but it was found impossible to obtain reproducible results with this electrode. The electrode was used in a study of the cadmium asparaginate and serinate systems and checked against a computer simulation. The best 'fit' was obtained from a value of mV/pCd far from the theoretical value of -29.586 and it was concluded that the glass electrode was the more reliable means of measuring titration data. The partition coefficient of the cadmium(II) glutathionate system was calculated for octanol/water as a model for cell membranes. This suggested a maximum of 2% of cadmium inside a cell being partitioned out by glutathionate and that ratios of ligand: metal greater than 1:1 would be the most efficient for complexing the metal. The Belousov-Zhabotinsky oscillating reaction was taken as a primitive model of biochemistry and the qualitative effect of introducing different materials to the system was noted. The computer program COMICS was modified for loading on to the St. Andrews IBM 560/44 computer and adapted to include three plotter routines.

In order to facilitate a later determination (which, incidentally, will involve the study of hyperfine structure) of various nuclear properties of Cadmium, a preliminary survey, both experimental and theoretical, has been undertaken of the gross spectral structure of that element. A light source, consisting of an electrodeless discharge in which the excitation of the various spectra could be varied in some degree, was constructed and conditioned. The illumination from this source was then photographed with the aid of a Hilger EI Quartz Spectrograph; exposures were taken of the regions 6800Å - 3300Å, 3300Å - 2500Å, and 2500Å - 2000Å. The positions of the spectral lines appearing on the plates were measured with the aid of a Hilger comparator, and the wavelengths were then calculated by means of the Standard Hartmann dispersion formula. About 150 Cadmium lines which had already been listed by previous workers were identified; 21 other lines - apparently new ones, since to the writer's knowledge they have not as yet been mentioned in the literature - also were found. These latter lines were concentrated in the region 6000Å - 3900Å. Theory reveals that the hyperfine structure of Cadmium II should be of greater value in the above-mentioned determination than that of the arc spectrum. Therefore a study of an isoelectronic sequence Involving Cadmium II was carried out with an eye to increasing the knowledge of this first spark spectrum's term structure. The validity of the various optical doublet laws has been tested for such an exemplary isoelectronic sequence. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The temperature and stress fields for the Vertical Bridgman growth of CdTe were calculated using the finite element method. The critical resolved shear stress (CRSS) of CdTe was measured at elevated temperatures. The measured CRSS and the calculated shear stress were compared to determine the onset of dislocation formation in the crystal. The effect of furnace gradient, crucible velocity, hot furnace temperature and cold furnace temperature on the solid/liquid interface shape and calculated resolved shear stress were examined using the model. Etch pit density measurments were carried out in order to verify the stress model. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

This work was undertaken to study the nature of the deformation mechanisms in polycrystalline zinc and cadmium over a temperature range from 77°K to 300°K. It has been observed that the only non basal slip system which is observed under normal light microscopy is that of second order pyramidal [ll22] <ll23>. At temperature above [formula omitted], the amount of non basal slip is greater in zinc than in cadmium. The amount of twinning, substructure formation and grain boundary migration is comparable in both systems. Negative work hardening beyond the U.T.S. at temperatures above Tн = .4 is associated with recrystallization. In both systems at temperatures below Tн = .26 a region of temperature and strain rate independent linear work hardening occurs. The extent of linear hardening increases with decreasing temperature below Tн = .26. Above Tн = .26, polycrystalline hardening in both systems is parabolic from yield on and the rate of hardening at a given value of strain decreases with increasing temperature. Cadmium single crystals showed a similar trend in that below .26 both [formula omitted] remained constant. However above .26 there was a steady decrease in the shear hardening rates. It was observed that the Cottrell-Stokes law is obeyed only in the linear hardening regions of polycrystals and in Stage II hardening of single crystals below .26. When dynamic recovery occurs [formula omitted] increases with increasing strain. It has been observed that below .26 the linear hardening rate in cadmium decreased with increasing grain size ( constant specimen dimensions) so that [formula omitted] The value of [formula omitted] was shown to correspond to the tensile hardening rate during Stage II single crystal deformation. The tensile hardening rate was used because of the extensive twinning found to be associated with Stage II hardening. The grain size dependence of 0 has been interpreted in terms of a grain size dependence of the extent of [ll22] <1123> slip. It was found that during linear hardening in both zinc and cadmium the difference in flow stress at two different temperatures is a reversible difference implying that the dislocation configurations produced with increasing strain do not vary in nature or extent with temperature. Under such conditions it is possible to formulate a mechanical equation of state. Extensive rate theory measurements have been made in both systems in order to attempt an evaluation of the rate controlling mechanisms both during linear hardening and.during dynamic recovery. The former has tentatively been associated with intersection. Dynamic recovery on the other hand has been linked to the loop annealing observations of Price. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

A systematic study of the Knight shift parameters has been carried out on single crystal specimens of tin and cadmium over a range from 1⁰ K to just below the melting points. The line widths observed in cadmium are approximately half the widths quoted by other workers, enabling more precise measurements to be made. These measurements show that the anisotropy of the Knight shift in cadmium changes sign between 4⁰ K and 77⁰ K. Pronounced changes in the Knight shift parameters are observed upon alloying cadmium with mercury. The temperature dependence of the isotropic Knight shift in tin can be explained by the volume effects and the phonon contributions when the temperature exceeds the Debye temperature. Comparing the temperature dependence data with pressure dependence results of other workers the explicit temperature dependence is extracted. It appears that the variation in the anisotropy of the Knight shift above the Debye temperature is largely caused by a change in lattice parameters, specifically a change in c/a ratio. Measurements of the line width at helium temperature in isotopically pure Sn¹¹⁹ and the same isotope in natural tin as a function of crystal orientation are reported. Second moments for the different crystal orientations have been computed. Analysis of the isotopically pure tin data leads to an evaluation of relative contributions, from the various shells, to the pseudo-dipolar interaction. For the isotopically pure tin, the measurements at the helium and room temperatures enable an evaluation of the spin-lattice relaxation time, T₁. T₁T is constant over the temperature range and closely isotropic. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The recovery of mechanical properties following deformation of single crystal cadmium has been studied. Such recovery has been observed above 0.26 TM [subscript omitted] (-120°C). Crystals covering a range of orientation were deformed in tension at -196°C and recovered at elevated temperatures. Transmission electron microscopy to relate tensile and recovery behaviour to dislocation structures was found to be impossible. It was observed that work hardening during the initial portion of the easy glide region is completely recoverable. At higher strains in easy glide, a portion of the work hardening was not recoverable. It is believed that in this latter section, dislocations are generated on the second order pyramidal system {1122} <1123>. These dislocations will combine with basal dislocations to form stable obstacles in the lattice which will be responsible for the non-recoverable work hardening. The end of easy glide was found to occur at x = 20°, independent of recovery or initial orientation. This phenomenon is associated with flow on the second order pyramidal system which will produce a much higher density of obstacles at this point, resulting in a higher work hardening rate. Recovery in stage II was observed to increase the amount of strain attainable. It was also observed that while recovery up to intermediate strains in stage II affected only basal dislocations, both basal and pyramidal dislocations appear to be recovered at high strains. Pyramidal dislocations may recover by the processes observed by Price. The rate controlling mechanism for yield and flow of cadmium single crystals is thought to be one of the non-conservative motion of jogs. An attempt was made to calculate an activation energy for the recovery process, but the data did not yield any meaningful numbers. This may be a result of the definition of recovery adopted for this work. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

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