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Item Morphological effects of pulsed Doppler diagnostic ultrasound on rat adult lung and fetal tissues : a thesis presented in fulfillment of the requirements for the degree of Master of Science in Physiology and Anatomy at Massey University(Massey University, 1999) Dulović, Stanica MilanThis study investigated morphological effects of diagnostic pulsed Doppler ultrasound on adult and fetal rat lungs from 16 to 22 days gestation. A clinical ultrasound machine with two types of focused transducers (3.5 MHz, 5MHz) was used with an adjustment for an experimental animal as small as a rat. Three levels of exposure were represented by a mechanical index (Ml) of 0.5, 0.6 and 1.0. Subpleural multifocal intra-alveolar haemorrhage was found to a significant degree in exposed adult rat lung and less significantly in fetal lung. The threshold for adult lung haemorrhage was considered to be between Ml 0.5 and 0.6. Fetal lungs were microscopically investigated by sectioning through the whole fetal body, which facilitated the discovery of haemorrhage at other sites. The percentage of exposed fetuses with haemorrhage is significant. A threshold for fetal haemorrhage could not be determined because a significant variation due to age within each exposure group affected the results. The oldest 21 and 22 day old fetuses had no lung haemorrhage or significant non-lung haemorrhage. The risk for haemorrhage at all three exposure levels is more than double that of non exposed fetuses. Fetuses with lung in the canalicular stage of development (18-19 day) showed the greatest degree of lung haemorrhage. Following laparotomy of the dam to achieve a precise and uniform exposure, a small number of fetuses within each exposure group was exposed directly. There was no higher degree of haemorrhage in these fetuses than in others indirectly exposed through the dam's abdominal wall. The fetal age dependency of fetal lung haemorrhage found in this study adds complexity to the issue of adult and fetal lung sensitivity to ultrasound and to the question of the pathophysiological role of cavitation in the presence of air. In addition, our result in 21-22day fetuses does not support the hypothesis that fetal haemorrhage is associated with developing bone. The results in this study were achieved using conditions commonly used in echocardiography and obstetrical ultrasound examinations. Therefore, caution is suggested in the medical use of ultrasound.Item Use of ultrasound in enhancing productivity of biotechnological processes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biochemical Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2011) Sulaiman, Ahmad Ziad BinThis study focused on identifying optimum sonication regimens (e.g. intensity, duty cycles) that may intensify bioprocesses without damaging the biocatalyst. Possible mechanisms of productivity enhancement in various biotechnology processing scenarios were investigated. Three model processes were used: 1) production of bioethanol from lactose by fermentation with the yeast Kluyveromyces marxianus; 2) β-galactosidase catalyzed hydrolysis of lactose in a homogeneous cell-free system; and 3) hydrolysis of soluble and insoluble particulate cellulose of various sizes, catalyzed by soluble cellulase. The above processes involved: 1) conversion of a soluble substrate by a live catalyst in the presence of gas-liquid mass transfer; 2) a cell-free homogeneous bioreaction system; and 3) a heterogeneous reaction system involving substantial solid-liquid mass transfer limitations depending on the size of the substrate (i.e. soluble and insoluble particulate cellulose). Low intensity ultrasound (11.8 W cm⁻² sonication power at the sonotrode tip), enhanced the ethanol productivity of the batch fermentation process. At the specified sonication intensity a duty cycle of 20% was found to be optimal. A duty cycle of 40% adversely affected the fermentation. With the best duty cycle of 20%, the final ethanol concentration was 5.2±0.68 g L⁻¹, or nearly 3.5-fold that of the control fermentation. The productivity enhancing effect of sonication was attributed to a possible improved desorption of carbon dioxide from the fermentation broth. Ultrasound may also have facilitated transport of lactose into the cell by affecting cell permeability. While ultrasound apparently enhanced desorption of carbon dioxide, it also damaged yeast enzymes such as β-galactosidase and this may explain why a 40% duty cycle had an adverse impact on the fermentation. Although at the highest duty cycle of 40% sonication reduced cell growth, cell viability remained high at ≥70% during most of the fermentation. In continuous fermentations, sonication always enhanced the steady-state biomass concentration and ethanol concentration at all dilution rates tested relative to the corresponding controls. Ultrasound effectively influenced enzyme-substrate binding/unbinding for β- galactosidase mediated hydrolysis of lactose in a cell-free system. A short irradiation pulse (i.e. 10% duty cycle), applied at the highest irradiation power (11.8 W cm⁻²), Use of ultrasound in enhancing productivity of biotechnological processes improved the initial hydrolysis rate, by nearly 1.4-fold relative to control. This effect of ultrasound was possibly due to its accelerative effect on collision frequency of the enzyme and substrate molecules as a consequence of the microturbulence caused by sonication. The cellulase-mediated hydrolysis of soluble cellulose as well as particulate cellulose was enhanced by sonication at a 10% duty cycle and power intensity of 11.8 W cm⁻², but prolonged sonication adversely impacted the enzyme stability at a constant temperature of 50 °C relative to control.