Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Florida, 1982. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 72-74).

No description available.

Thesis (DTech (Science))--Peninsula Technikon, Cape Town, 2003. / The impetus for the refinement and renewal of daily-used products has spurred international interest in investigating the small in homogeneities that might exist in these products. This interest has become an important part in the design philosophy, which is based on structural information gained by the analysis of these products. It is this drive that initiated the study to investigate the simultaneous use of novel nuclear analytical techniques such as micro proton induced X-ray emission( u-PlXE), micro proton induced gamma-ray emission (u-PlGE) and micro proton backscattering (u-RBS) to achieved a broader and yet deeper insight into the fine structure of products. The fundamental underlying physical principles of these techniques are discussed to gain in-depth knowledge on how to them to obtain the desired information. Also determined was the degree of accuracy that could be attained in the application of this knowledge. These principles were evaluated in conjunction with the instrumentation with which the applicability of these techniques could then be further extended. More so is the use of sophisticated software that facilitated the use of both physical and instrumental parameters. After describing the necessary implements to achieve this further know-how, products of industrial origin were investigated to determine in homogeneities that existed in those products and compared those theoretical values. The first application was made to ceramic-based sorption electrodes to be used in the purification of wastewater.

D.Tech. (Biomedical Technology) / Stem cells are defined as undifferentiated cells that can proliferate and have the capacity of both self-renewal and differentiation to one or more types of specialised cells (Bishop et al., 2002). The two types of stem cells are embryonic and adult stem cells. Adult stem cells have been isolated from adipose tissue in abundance and with ease (Mvula et al., 2010) and these cells have been differentiated into smooth muscle cells (SMCs) with the enhancement of low intensity laser irradiation and the growth factors (de Villiers et al., 2011). Smooth muscles play an important role in diseases like cancer, hypertension, asthma and others (Rodriguez et al., 2006). Studies have shown that low intensity laser irradiation (LILI) can increase proliferation of cells, cellular attachment, differentiation and production of transforming growth factor-beta 1 (TGF-β1) in cells indicating that in vitro LILI can modulate the activity of cells and tissues (Khadra et al., 2005). Further studies have also discovered that LILI enhances wound healing (Fiszerman and Markmann, 2000). LILI has been successfully used for pain attenuation and to induce wound healing in non-healing defects (Hawkins and Abrahamse, 2005). LILI has been shown to increase viability and proliferation of adipose derived stem cells (ADSCs) (Mvula et al., 2008 and Mvula et al., 2010). Growth factors such as retinoic acids (RA) have been shown to have major influences on cells. They are involved specifically in apoptosis, cell proliferation, differentiation and maturation (Duong and Rochette, 2011; Gudas and Wagner, 2011). Co-culturing is used to achieve several cellular processes including proliferation, differentiation and migration (Kim et al., 2012). When two types of cells are cultured together, they are exposed to a number of complex environmental factors such as cytokines, extracellular matrix components, cell interactions, mechanical stimuli, signalling transcriptional pathways and transcriptional factors such as growth factors. v These factors are able to affect migration, proliferation and differentiation of one cell type into another (Zhang et al., 2012). The aim of this study was to investigate the differentiation potential of ADSCs when co-cultured with (SMCs) and to determine the role of LILI on the co-cultured cells. Short and long term biological effects were monitored on these cells following exposure to LILI and addition of growth factors. The study used commercial and isolated human ADSCs and SMCs (SKUT-1) cells. After growing cells to semiconfluency for ADSCs and confluency for SMCs, they were co-cultured in a ratio of 1:1 using the established methods supplemented with and without growth factors (TGF-β1and RA) and then exposed to LILI. The cellular morphology, viability and proliferation activities of the irradiated cells were then assessed using direct inverted and differential interference contrast microscopy (DIC), trypan blue test, adenosine triphosphate luminescence, optical density analysis, and carboxyfluorescein diacetate succinimdyl ester (CFSE) methods. In particular the expression of the specific markers of both ADSCs, β1 Integrin (CD29) and Thy-1 (CD90) and SMCs, Myosin Heavy Chain (MHC) were investigated through immunoflourescent microscopy and flow cytometric analysis. Up and down regulation of genes involved in the human mesenchymal stem cell array were analysed through Reverse Transcriptase Polymerase Chain Reaction (RTPCR)...

Chicken breast muscles (Pectoralis major and Pectoralis minor) were subjected to low doses of gamma radiation (≤ 0.50 Mrad) within 20-30 min. post-slaughter. pH decline extractability of different muscle protein fractions, shear force, isometric tension pattern and sarcomere length were evaluated at definite intervals of post mortem storage period. pH measurements from 1/2 hour to 72 hours post mortem revealed a stimulation of pH decline immediately after irradiation in 0.25 and 0.50 Mrad treated muscle samples but this effect was subsequently found to be nullified and an ultimate pH of about 5.55 was reached between 6-12 hours in all the samples. Extractability of total soluble and total myofibrillar proteins of muscle increased with post mortem time. A clear effect of irradiation treatments of increased extractability of actomyosin especially in the post rigor period was observed and this effect was more noticeable in 0.50 Mrad than in 0.25 Mrad samples. Comparatively less extractable actomyosin was found during the post rigor period of storage particularly in control samples. There was no significant effect of radiation doses, time of storage or their interactions on the solubility of sarcoplasmic proteins or of four minor fractions of protein and non-protein substances. The level of extractable actomyosin was found to be significantly related (r² = 0.12; df=46) with the corresponding shear press measurements. Irradiated samples had significantly higher mean shear values and more extractable actomyosin than the control samples especially during the post rigor period. Irradiation (0.125 and 0. 250 Mrad) was found to stimulate post mortem development of isometric tension in muscle strips. In irradiated samples maximum tension was developed about 2 hours ahead of the corresponding controls. A 50% decline of isometric tension was achieved in 6-8 hours post mortem, while a 50% decline of tension in control samples required more than 12 hours. The general relationship of isometric tension pattern and extractability of actomyosin was found to be low. Sarcomere length was related (r² = .38; df = 6) with shear values such that a small change in sarcomere length was found to result in a relatively large change in shear press values. Irradiated samples with relatively shorter sarcomeres in the post rigor period were found to have significantly lower mean shear values when compared with their respective control samples. / Land and Food Systems, Faculty of / Graduate

The total water uptake, rate of water uptake, extract release volume and maximum shear force were measured on a series of samples of irradiated freeze-dried beef. Forty seven pieces of round steak (2.5 cm x 2.5 cm x 10.4 cm or 1" x 1" x 4") were irradiated at one, three and five megarad. The control samples were not irradiated. Half of the samples were irradiated when fresh, and the other half were irradiated after freeze drying. This procedure has been defined as the "fresh-dry" irradiation sequence throughout the report. The samples were frozen in an air blast at two temperatures (-22.2°C and -56.1°C). Freeze-drying was carried out below 300 microns of Hg and a maximum shelf temperature of 15.6°C (60°F). There appears to be three phases of water uptake: 1) A very rapid, almost instantaneous, absorption. 2) A more gradual uptake (called Part.1 in the report). 3) A relatively slow asymptotic approach to an equilibrium condition (Part 2). These two last phases are shown to be straight lines when the logarithm of the water uptake is plotted against the logarithm of the immersion time. Irradiation level has no significant effect on the final water content or on the slow asymptotic absorption (Part 2) or the extract release volume, but has a significant effect on the gradual water uptake (Part 1) and on the shear press force. Fresh-dry irradiation sequence (and freezing rate) have a significant effect on the total water uptake and on the slow asymptotic water (Part 2) uptake, but not on the gradual water uptake (Part 1), or on the extract release volume or on the shear press forces. Freezing rates have a significant effect on the total water uptake, but not on the slow asymptotic water uptake (Part 2), on the gradual water uptake (Part 1), on the extract release volume or on the shear press forces. The highest total water uptake was found for the meat irradiated when fresh, and slow frozen at -2 2.2°C. The mechanism of the gradual absorption appears to follow a phenomena of water flow, as evidenced by the straight line relationship found in the plots of logarithm water uptake versus logarithm immersion time. / Land and Food Systems, Faculty of / Graduate

Emission of electromagnetic radiation due to the temperature of a body is an inherent property in nature. Electromagnetic radiation sources relying on thermal emission are critical in application of energy harvesting, lighting, spectroscopy and sensing. However, many of these sources, typically made of several hundreds of microns thick bulk objects, are inefficient and radiate much less power than an ideal blackbody. In the first part of this work, we demonstrate an efficient thermal emitter based on material films that are nanometers thin. Nano-film based thermal sources are generally poor emitters, but have received much interest lately since they require significantly lower heating power compared to their bulk counterparts. We show a novel approach for realizing thin-film based blackbody emitters by placing them inside an external optical cavity, engineered to provide enhancement of thermal emission while maintaining a constant temperature. Our approach is independent of the emitter material and can be tuned to operate at any temperature since the optical elements and the emitter are physically disconnected. The work opens new avenues for realizing blackbody-type thermal sources consuming significantly lower heating power than the current state-of-art, thus suggesting direct applications in lighting, spectroscopy and energy harvesting. Furthermore, we utilize the nano-film broadband emitters for demonstrating heat transfer that beats conventional blackbody limit at deep-subwavelength distances. We demonstrate the first of its kind, fully integrated and re-configurable thermo-photovoltaic on silicon platform. We report over an order of magnitude increase in generated electrical power by electro-statically tuning the distance between a suspended hot emitter TE ~ 880 K) and an underlying detector (maintained at TD ~ 300 K) from ~500 nm to ~100 nm. We believe this demonstration will be influential for the fields of active energy harvesting as well as in realizing integrated thermal control systems. In the third part of this work, we shift our focus away from broadband emitters, towards spectrally narrow band thermal emitters and propose a novel technique for long-distance transport of thermal radiation. In order to do so, we rely on enhanced near-field heat transfer over blackbody limits aided by surface plasmon polaritions (SPP). We then show that a dispersion engineered sub-wavelength waveguide can allow required states for SPP aided electromagnetic emission to propagate. We show computational analysis of the a composite structure using the open-source electromagnetic solvers SCUFF-EM that captures the effects of surface current distribution induced electromagnetic field effects inside and outside the emitter. We furthermore show a prototype structure of the proposed thermal-waveguide with doped silicon emitters that support SPP. We discuss the measurement technique and present preliminary results of thermal transport over a waveguide that is ~34 μm long. We believe that our proposed approach shown here could advance the field towards development of novel devices for thermal control.

No description available.

Using a micro-potometric method, it was ,found that X-irradiation (400 R - 18 Kr) of the shoots of the onion plant Allium cepa will produce an immediate, pronounced (200%) and reversible enhancement of the water uptake by the shielded roots. Unfiltered X-irradiation.(1200 R/min., 120 KVP, 5 ma) was delivered at right angles to the shoot. Readings were taken at 10-minute intervals before, and immediately following X-irradiation. The greatest enhancement occurred at dosages between 4.8 Kr (150%) and 6.0 Kr (190%). The data indicate that the irradiation effect on water uptake was a physical rather than a metabolic one.