Since the early 1980s the increase in use of pulse oximeters in many clinical situations has been quite remarkable, turning it into one of the most important methods of monitoring in use today. Pulse oximetry essentially uses photoplethysmography to calculate oxygen saturation. Consequently the wavelength dependence of the photoplethysmogram (PPG) is of direct relevance in the performance of pulse oximeters. The experimental results obtained on the wavelength dependence of the AC, DC and AC/DC PPG components for the 450 - 1000nm range are undoubtedly different to the ones predicted by the current simple pulse oximeter model based on the Lambert-Beer law. Moreover, they show unexpected phenomena regarding the magnitude of the above components over the whole range, with distinct differences between the reflection and transmission modes. This is of significance to the technique of pulse oximetry suggesting that perhaps other wavelengths should be considered for use, and that use of both "reflection" and "transmission" probes on the same oximeter may lead to inaccurate readings in one of the modes. A finger model was developed and results from Monte Carlo simulations of photon propagation obtained. The results did not correspond to the experimental results, this is most probably due to either wrong parameters or model. Recent advances in the use of reflection pulse oximeters on fetal monitoring during labour, have raised the question of possible artifacts which may arise due to inadequate probe application in the birth canal. The importance of complete opposition of the reflectance probe was examined on an adult finger. False low oxygen saturation readings were recorded with malpositioned probes. A new probe with modified geometry was designed which offered an improved performance in reducing this artifact and further suggestions were given for its possible elimination. Finally, a proposal for a novel, visible multi-wavelength reflection pulse oximeter is presented with the aim of replacing current pulse oximeters in certain situations where their use is questionable.

Left ventricular assist devices (LVADs) are an increasingly utilized therapy for end-stage heart failure. Thrombosis within the graft from the pump to the aorta has been documented, but is poorly researched. This study examines the effect of graft geometry, as measured by radius of curvature, bend angle, and diameter, on thrombogenic flow patterns within the graft for a range of flow conditions. It also examines the effect blood properties, including viscosity and density, on these flow patterns. The results indicated that radius of curvature had a powerful effect on thrombogenic flow patterns. Flowrate and bend angle were also influential. The results of this study offer insight on how graft geometry may interact with flow conditions and blood properties to produce regions of stagnation or recirculation within the outflow graft, which may precipitate thrombogenesis and pose a risk to patients.

This thesis describes the development of a generic design methodology for variable camber flap systems for transport aircraft, intended to be used for cruise and low-speed operations. The methodology was structured after several revisions were performed on conventional high-lift device design methodologies for existing transport aircraft. The definition and detail explanations are given at every phase of the methodology. A case study was performed in order to give an example of the implementation of the methodology where a transport aircraft called A TRA, a design study from previous PhD report, was taken as a model. Experimental work could not be performed, due to budget constraints, so the case study was only carried out using computer-based analyses. Software packages such as MSES-code (a Computational Fluid Dynamic software), CATIA and PATRANINASTRAN were used for this case study to analyse aerodynamic characteristics, layout as well as simulation and structure analyses respectively. The results obtained showed that it was practically feasible to deploy such a high-lift device to transport aircraft when the effect from aerodynamic loads gave minimum effect on structural deformation. The deflections of the flap as well as spoilers under critical loads were below the allowable limits, which had a minimal effect due to the additional lift force generated from the movable surfaces.

The purpose of the study was to determine the adherence to and usage of the N95 respirator mask as a TB control measure in healthcare facilities in the Tshwane district during managing a patient suspected or confirmed with pulmonary TB infection. A cross-sectional, descriptive survey design was used to collect the data. A sample of 204 healthcare professionals and healthcare workers working in five healthcare facilities in the Tshwane health district met the inclusion criteria for this study. More than 83.33 %( n=170) of the staff were nurses; physiotherapists in the healthcare facility constituted the lowest percentage (1.96%; n=4). Chi-square test was done to test whether there was a significant difference between knowledge on the fit test of the N95 respirator mask and the healthcare professionals and healthcare workers. There was no significant difference in knowledge across the five staff categories P-value of >0.05. Ensuring successful protection of the healthcare workers from contracting M-TB in the TB healthcare facilities depends on effective implementation of a respiratory protection programme and the correct usage of the N95 respirator mask.

University of Macau / Institute of Chinese Medical Sciences

University of Macau / Faculty of Science and Technology. / Department of Electromechanical Engineering

Typescript, etc.

Nanotechnology is the manipulation of matter at the supramolecular, molecular and atomic scale. As a result, nanotechnology is included in various fields of science including surface science, organic chemistry, molecular biology, semiconductor physics, microfabrication and molecular engineering. One of the ambitions for nanotechnology is to develop electrical devices where the active component is a single molecule or nanomoiety. In order to fabricate such devices, it is of paramount importance to develop strategies beyond the current top-down lithographic approaches typically employed in the semiconductor industry. In this regard, the ability to control the assembly of single-molecules and individual nanomoieties directly in solution can allow for the development of solution-processable approaches in nanotechnology, towards the fabrication of single-molecule devices. In this thesis, it will be discussed how molecular junctions with functional single molecules are fabricated in aqueous solutions employing single-walled carbon nanotubes as potential nanoelectrodes. Furthermore, it will be demonstrated how the assembly of molecular junctions can facilitate other functions and the construction of both nanostructures and microstructures. To begin, relevant work will be discussed that has been done in this field to date and outline clear ambitions of the study presented here. Subsequently, the key characterisation techniques that underpin all the results in this study will be described. In this work, it will be reported how metallic carbon nanotubes can act as nanoelectrodes in molecular junction assemblies and how conductive measurements of individual molecules are performed. Therefore, for the first time, the molecular junction conductance of a series of oligophenyls were successfully measured, which were formed via a solution-based assembly method. Measured molecular conductance values of the series of oligophenyls resulted in a β value of 0.5 Å−1. Furthermore, it will be described how the approach outlined previously can be extended to the synthesis of tri-amine molecular linkers as well as the formation of three-terminal junctions as the foundation of carbon nanotube-based single-molecule electronic devices. This research resulted in an increase in the formation of Y-shape molecular junctions by ~25%. Next, this report will outline the formation of molecular junctions in two-dimensional structures, which can allow for the development of electrical devices into networks. Utilising modified DNA sequences, "click" chemistry can lead to nanotube network with dimensions ranging into the micrometre scale. Building on this work, it will be further report on the change in physical properties when these two-dimensional superstructures are embedded into polymeric thin films. Finally, conclusions of the research will be drawn and it will be discussed how the findings obtained in this work can contribute to the development of novel single-molecule electronic devices.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Alan Palevsky. / Ph.D.

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