This dissertation describes the effects of tetrastarch (130/0.4) on serum colloid osmotic pressure and thromboelastography variables in healthy pony mares. Additional variables assessed during this study included markers of haemodilution (PCV, TS) and serum creatinine and bile acid concentrations. Six clinically healthy Nooitgedacht pony mares were utilized in a crossover study design. Tetrastarch (130/0.4) was administered at 10, 20 and 40 ml/kg bwt to each mare in a random sequence with a two week washout period between each of the treatments. Packed cell volume (PCV), plasma total solids (TS), serum colloid osmotic pressure (COP), and platelet count were measured and thromboelastography (TEG) was performed before treatment (baseline), immediately after infusion (time 0), and 1, 6, 12, 24, 48, and 96 h after tetrastarch infusion. All TEG variables remained within reference range in all treatment groups. Administration of tetrastarch at 40 ml/kg bwt resulted in a prolonged K-time at 6 h post-infusion, and decreased maximum amplitude at 0, 1, 6, 24 and 48 h post-infusion compared to baseline. Administration of tetrastarch increased mean COP values above baseline in all three treatment groups, persisting to 24, 6 and 48 h after treatment with 10, 20 and 40 ml/kg of tetrastarch respectively. This study concluded that, although values remained within established reference ranges, the administration of tetrastarch (130/0.4) at 40 ml/kg bwt is more likely to induce changes in TEG variables than doses of 20 ml/kg or less. Tetrastarch increased COP in healthy horses at all evaluated dose rates. / Dissertation (MMedVet)--University of Pretoria, 2014. / gm2014 / Companion Animal Clinical Studies / unrestricted

<p> There is a great need for sensors that can infer the properties of polymer latices. Measuring ultrasonic wave travel parameters through a latex and calibrating these against polymer properties is one potential technique for measuring the polymer properties of a latex without separating the polymer particles from water. Ultrasonic longitudinal waves can be characterized by three travel parameters: the velocity, the attenuation and the frequency. For colloidal systems the attenuation will depend on molecular properties of the system inside a frequency window where diffraction and scattering are negligible.</p> <p> In this thesis the equipment for measuring ultrasonic waves is discussed and a measurement cell for measuring waves in liquids is designed and built. This equipment is used to measure the velocity and attenuation as functions of frequency for two sets of copolymer latices. These latices were measured separately using a combination of standard quality control analyses and polymer characterization techniques. It was discovered that the velocity of sound through latices does not differ significantly from the velocity for pure water while the ultrasonic attenuation of latices at solids concentrations of greater than 10 percent is much greater than the value for pure water.</p> <p> For the copolymer latices produced from styrene and methyl-methacrylate the attenuation measurements were all too similar to distinguish between changes in the properties of the latex. For the copolymer latices produced from styrene and butadiene, the attenuation and composition were related by an approximately linear relationship between 30 and 80 mole percent styrene. In this region, the attenuation spectra were regressed onto the property space using a linear multivariate algorithm called projection to latent structures. It was found that the attenuation is only useful for predicting latex properties that are related to composition in this range. Future work should focus on the use of a non-linear regression technique to model the behaviour of attenuation over the entire composition range and the use of independent analyses to better characterize some of the polymer properties such as crosslinking.</p> / Thesis / Master of Engineering (MEngr)

Laser-induced breakdown spectroscopy (LIBS) is an advanced data analysis technique for spectral analysis based on the direct measurement of the spectrum of optical emission from a laser-induced plasma. Assignment of different atomic and ionic lines, which are signatures of a particular element, is the basis of a qualitative identification of the species present in plasma. The relative intensities of these atomic and ionic lines can be used for the quantitative determination of the corresponding elements present in different samples. Calibration curve based on absolute intensity is the statistical method of determining concentrations of elements in different samples. Since we need an exact knowledge of the sample composition to build the proper calibration curve, this method has some limitations in the case of samples of unknown composition. The current research is to investigate the usefulness of ANN for the determination of the element concentrations from spectral data. From the study it is shown that neural networks predict elemental concentrations that are at least as good as the results obtained from traditional analysis. Also by automating the analysis process, we have achieved a vast saving in the time required for the data analysis.

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Chemical control is a critical component of integrated pest management in cotton and soybean production. Residual efficacy of foliar insecticides can be highly variable and difficult to quantify due to several factors. The purpose of this research was to determine residual control and concentrations in flowering structures of commonly used insecticides. This research focused on the concentrations of active ingredient within the plant as well as efficacy over time. Previous research suggested chlorantraniliprole had a long residual and was highly lethal on corn earworm up to 28 days after treatment (DAT) in soybean; however, the results found in cotton were inconclusive. From this research, concentrations of chlorantraniliprole were found in flowering structures of both soybean and cotton up to 14 DAT. Bioassays conducted from chemical concentrations suggest reduced rates of chlorantraniliprole, similar to what was found in the flowering structures, provided mortality of corn earworm up to 64%.

Abstract Not Provided. / Thesis / Master of Science (MSc)

Photodynamic therapy (PDT) currently utilizes drug and light doses which are primarily based on clinical experience. This can lead to a dose which is not sufficient to destroy the entire tumor, or alternatively, it can lead to the undesirable destruction of healthy tissue around the treatment area. PDT of topically applied photosensitizers is one focus of this research. This concerns the diffusion of an externally applied drug into the tissue, as well as its subsequent destruction during the irradiation procedure. This work involves the non-invasive measurement of the inherent fluorescence of the photosensitizer, allowing the determination of the concentration and distribution of drug within the tissue, and thus optimizing this treatment. To do this, one must be able to describe the propagation of light within the tissue. Consequently, a photon diffusion model has been developed to calculate the steady-state spatially resolved fluorescence from a pencil beam excitation in a depth dependent medium. The validity of this model was then verified by comparison with Monte Carlo simulations and measurements made on phantoms with optical properties similar to those of human tissue. Theoretical conditions were then explored, and potential uses of the model were demonstrated. / Thesis / Master of Science (MS)