This research project compares different chemical and spectroscopic techniques aimed at finding a quick and cheap replacement for the measurement of digestibility of phosphorus (P) in different inorganic feed additives for pigs. This research yielded a comparison of the digestibility of different feed additives. P digestibility was determined from in vivo studies of pigs. The animal feed in the in vivo studies contained P levels below the nutrient requirements. The basal diet was a corn soybean meal base. Assessment was performed on 6 different inorganic P sources, rock phosphate (tricalcium phosphate (TCP)), meat and bone meal (MBM), mono/dicalcium phosphate (MDCP) and three different dicalcium phosphates (DCPs). Eight pigs where selected and placed into separate pens. Two were given basal diets and the other 6 diets were randomly selected and supplied with the different inorganic P sources. P digestibility was calculated by difference. The apparent P digestibility of the sources were: TCP at 46 %, the MBM at 85 %, MDCP at 71 % and three DCPs ranged from 49 % to 73 %. This substantiated that the apparent P digestibility in the major inorganic sources of P is significantly less than 100%. The in vitro or chemical methods of assessing phosphorus availability in animal feed included the commonly used feed extraction methods of water solubility and 2 % citric acid. These two methods showed significant differences between each other. Other chemical methods used included calcium chloride, ammonium acetate, sodium bicarbonate extractions, and a double extraction using hydrochloric acid (HCl) followed by sodium bicarbonate. The chemical methods showed non-significant correlation coefficients when compared to in vivo P digestibility of the six phosphate ingredients used. Infra-red spectroscopy is now commonly used in feed production for many other nutritional tests. NIR, although being able to obtain an R2 above 0.999 for correlation curves and factor prediction curves, could not obtain a self prediction of the calcium phosphates due to the large Mahalanobis Distance. P digestibility predicted by MIR showed close agreement with the in vivo P digestibility. Again due to the small number of ingredients tested in the pig trial, the prediction of digestibility using MIR could only be compared to it self. Hence MIR can only be used as an estimate until more data can be obtained. The P31 SS-MAS-NMR indicated one of the DCPs was made up of 3 or more P compounds by displaying 3 major peaks. All the P chemical shifts from the faeces had different positions to the P peaks in the ingredients, indicating some sort of change in the P form. Overall the chemical methods were unable to predict P digestibility, and while the spectroscopic techniques showed promise, they still require more work to examine many more feed additives.Invitro, invivo, phosphorus, digestibility, swine, infra-red spectroscopy, solid state NMR

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Hand-held optical imagers are developed towards clinical breast cancer imaging. Herein, a Gen-2 hand-held optical imager has been developed with unique features: (i) image curved breast tissues with ~86% surface contact, and (ii) perform reflectance and transillumination imaging using the novel forked probe heads. Extensive phantom studies were performed using 1% Liposyn solution (background, ~ 300 ml and 1000 ml volumes) and 0.45 cc India Ink (absorption) targets, under different target:background contrast ratios and target depths. Two-dimensional surface images detected target(s) up to 2.5 cm deep via reflectance imaging, and up to 5 cm deep via transillumination imaging. Preliminary studies on gel-based breast phantoms (~700 ml) detected targets via reflectance and transillumination imaging. Preliminary in-vivo reflectance studies on normal and cancerous breast tissues also detected targets, although with artifacts. In future, the portable Gen-2 imager has potential for clinical breast imaging via reflectance and transillumination approach after extensive in-vivo studies.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The monitoring of patients in healthcare is of prime importance to ensure their efficient treatment. The monitoring of blood oxygen saturation in tissues affected by diseases or conditions that may negatively affect the function is a field that has grown in importance in recent times. This study involved the development and testing of a highly sensitive noninvasive blood oxygen saturation device. The device can be used to continuously monitor the condition of tissue affected by diseases which affect the blood flow through the tissue, and the oxygen usage in tissue. The device’s system was designed to specifically monitor occluded tissue which has low oxygen saturations and low perfusion. With the use of the device, it is possible to monitor the status of tissue affected by diseases such as meningococcemia and diabetes mellitus or conditions such as the recovery after plastic surgery. The study delved into all aspects involved in the development of a non-invasive artificial pulse oximeter, including but not limited to that of a detailed device design, signals analysis, animal in-vivo and laboratory in-vitro system design for the calibration of the system as well as human clinical validation and testing procedures. All these aspects were compared to determine the relative accuracies of the different models. Through testing it was shown that it is possible to non-invasively measure the mixed oxygen saturation in occluded tissue. However, without accurate validation techniques and methods of obtaining both arterial and venous blood samples in occluded tissue the system could not be fully validated for determining both the arterial and venous oxygen saturations in the human invivo study. Although the system was unable to accurately measure specifically the venous oxygenation it was able to measure the mixed oxygen saturation. With further research it would be possible to validate the system for measuring both the arterial and venous oxygen saturations. / AFRIKAANSE OPSOMMING: Die monitering van pasiënte in gesondheidsorg is van uiterste belang om doeltreffende behandeling te verseker. Die monitering van bloedsuurstofversadiging in weefsels wat geaffekteer word deur siektes of toestande wat ’n negatiewe impak kan hê op die funksie daarvan is ’n gebied wat aansienlike groei getoon het in die onlangse verlede. Die studie het die ontwikkeling en toetsing van ’n hoogs sensitiewe nieindringende bloedsuurstofversadigingsensor ingesluit. Hierdie sensor kan gebruik word om deurentyd die toestand van weefsel te monitor wat geaffekteer word deur siektes wat bloedvloei deur weefsel affekteer sowel as die suurstofgebruik in die weefsel. Die stelsel is ontwerp om spesifiek die ingeslote weefsel wat lae suurstofversadiging en lae perfusie het, te monitor. Deur gebruik te maak van die toestel is dit moontlik om die toestand van die weefsel wat geaffekteer word deur siektes soos meningococcemia en diabetes mellitus of toestande soos die herstel na plastiese sjirurgie te monitor. Die studie het gekyk na alle aspekte wat betrokke is in die ontwikkeling van ’n nie-indringende kunsmatige pols-oksimeter, insluitend maar nie beperk tot gedetailleerde ontwerp nie, sein analise, dier in-vivo en laboratorium in-vitro stelselontwerp vir die kalibrasie van die stelsel sowel as menslike kliniese bekragtiging en toetsprosedures. Al hierdie aspekte is vergelyk om die relatiewe akkuraatheid van die verskillende modelle te bepaal. Die toetse het gewys dat dit moontlik is om nie-indringend die gemengde suurstofversadiging in weefsel te bepaal. Sonder akkurate bekragtigingstegnieke en metodes om beide arteriële en vene bloedmonsters te versamel in ingeslote weefsel kan die stesel nie ten volle bekragtig word om beide arteriële- en veneversadigings in menslike in-vivo studie te bepaal nie. Hoewel die stelsel nie ’n akkurate meting van die aarsuurstof kon kry nie, is daar wel ’n akkurate meting geneem van die gemengde suurstofversadiging. Toekomstige navorsing kan lei tot die bekragtiging van die stelsel om beide arteriële en slagaar suurstofversadigings te meet.