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151	An Assessment of Novel Biodegradable Magnesium Alloys for Endovascular Biomaterial Applications Persaud-Sharma, Dharam 10 June 2013 (has links) Magnesium alloys have been widely explored as potential biomaterials, but several limitations to using these materials have prevented their widespread use, such as uncontrollable degradation kinetics which alter their mechanical properties. In an attempt to further the applicability of magnesium and its alloys for biomedical purposes, two novel magnesium alloys Mg-Zn-Cu and Mg-Zn-Se were developed with the expectation of improving upon the unfavorable qualities shown by similar magnesium based materials that have previously been explored. The overall performance of these novel magnesium alloys has been assessesed in three distinct phases of research: 1) analysing the mechanical properties of the as-cast magnesium alloys, 2) evaluating the biocompatibility of the as-cast magnesium alloys through the use of in-vitro cellular studies, and 3) profiling the degradation kinetics of the as-cast magnesium alloys through the use of electrochemical potentiodynamic polarization techqnique as well as gravimetric weight-loss methods. As compared to currently available shape memory alloys and degradable as-cast alloys, these experimental alloys possess superior as-cast mechanical properties with elongation at failure values of 12% and 13% for the Mg-Zn-Se and Mg-Zn-Se alloys, respectively. This is substantially higher than other as-cast magnesium alloys that have elongation at failure values that range from 7-10%. Biocompatibility tests revealed that both the Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. Gravimetric and electrochemical testing was indicative of the weight loss and initial corrosion behavior of the alloys once immersed within a simulated body fluid. The development of these novel as-cast magnesium alloys provide an advancement to the field of degradable metallic materials, while experimental results indicate their potential as cost-effective medical devices. Magnesium Alloys Biodegradable Stents Corrosion Corrosion Science Mg-Zn-Cu Mg-Zn-Se Mg-Zn Biocompatibility Mechanical Properties Absorption Multi-Vitamin Effect Tissue Growth Magnesium Corrosion Control Magnesium Stents Biodegradable Stents Cardiovascular Endovascular Medical Devices Medical Device Minimally Invasive Endovascular Device Dharam Persaud Dharam Persaud-Sharma Biomaterials Biomedical Devices and Instrumentation Equipment and Supplies Surgical Procedures, Operative Therapeutics
152	USING NONINVASIVE CALIBRATED CUFF PLETHYSMOGRAPHY TO OBSERVE THE EFFECTS OF COLD-WATER IMMERSION ON ARTERIAL COMPLIANCE Grigorian, Rita M 01 October 2023 (has links) (PDF) As the prevalence of cardiovascular diseases continues to exponentially grow in populations across the globe, the necessity of determining underlying factors, effective methods of diagnoses, and universally available preventive measures also grows. Early detection of endothelial dysfunction, a proven precursor of cardiovascular diseases, can be extremely impactful in encouraging preventative measures and early intervention before medical conditions become chronic. In recent years, ice plunging, a form of cryotherapy involving full body immersion in cold water, has gained popularity within circles of fitness and health practitioners, gaining the interest of people of all backgrounds. Certain parallels observed between the human physiological response to cold exposure and endothelial function encourage further study of the effects of ice plunging on cardiovascular health. Calibrated cuff plethysmography is a promising method of reflecting on endothelial function by measuring arterial compliance of select blood vessels. In this study, a calibrated cuff plethysmography device was built and tested for efficiency as it was used to measure compliance and cross-sectional area of the brachial artery of 14 participants 30 minutes before, immediately after, and 30 minutes after a 5-minute cold plunge in a temperature of 10°C - 15°C. Results found some significant differences between baseline measurements recorded immediately after the ice plunge and measurements recorded during reactive hyperemia conditions at normal body temperature but did not conclude that 5-minute cold-water immersion intervention had a significant impact on arterial compliance or area overall since this was a short term experiment with only acute intervention methods. The device used was concluded to effectively measure arterial compliance and area. Endothelial Dysfunction Cold-Water Immersion Angiogenesis Thermogenesis Calibrated Cuff Plethysmography Cardiovascular Disease Biomedical Devices and Instrumentation Cardiology Cardiovascular Diseases Exercise Physiology Homeopathy Human and Clinical Nutrition Medical Anatomy Medical Pathology Other Nutrition Quality Improvement Sports Medicine
153	MICROFLUIDIC DEVICES FOR NEMATODE-BASED BEHAVIOURAL ASSAYS USING ELECTROTAXIS Rezai, Pouya 04 1900 (has links) <p>Small nematode model organisms such as <em>Caenorhabditis elegans</em> are widely used in the fields of neurobiology, toxicology, drug discovery, etc. They are advantageous due to their fully characterized genomic and cellular system. Traditional screening methods involve the exposure of animals to chemicals/drugs inside multiwell-plates while its effects on growth, movement and other cellular/sub-cellular processes are monitored by visual inspection. Yet, these methods are time-consuming, low-throughput, expensive, tedious, difficult to control, hard to modulate instantaneously, prone to subjectivity and not suitable for movement-based behavioural assays. Hence, a method to induce and to quantify movement on-demand in a rapid, sensitive, precise and reversible manner would greatly facilitate biological studies. In this thesis, microfluidic engineering approaches have been utilized in nematode-based assays due to their potential to obtain high precision measurements in a low-cost, rapid and automated manner. Movement response of worms to a diverse range of electric signals has been quantitatively characterized. DC and pulse-DC electric fields have been shown to stimulate worms’ swimming towards the negative electrode inside a microchannel (electrotaxis). AC electric fields were used to inhibit movement on-demand. Animals’ movement has been characterized in terms of speed and range of motion, body-bend frequency and turning time. Electrotaxis was shown to be mediated by neuronal activities and correlations between animal’s behaviour and neuronal signalling has also been demonstrated. Using this basic understanding, multiple microfluidic components such as position sensors and electric immobilizers have been developed. Electrotaxis has then been applied as a technique to sort worms in accordance to their size/age and phenotype as well as to perform drug screening at a single-animal level. Integration of the techniques and components developed during this research is expected to have a significant impact on the development of an integrated microfluidic platform for high throughput automated behavioural screening of nematodes with applications in drug discovery, toxicology, neurobiology and genetics.</p> / Doctor of Philosophy (PhD) Nematode C. elegans Electrotaxis Microfluidic Movement Assay Drug Screening Immobilization Sorting Detection Localization Animal Sciences Behavioral Neurobiology Bioelectrical and neuroengineering Biological Engineering Biomechanical Engineering Biomechanics and biotransport Biomedical devices and instrumentation Biotechnology Electro-Mechanical Systems Animal Sciences
154	Vision Beyond Optics: Standardization, Evaluation and Innovation for Fluorescence Microscopy in Life Sciences Huisman, Maximiliaan 01 April 2019 (has links) Fluorescence microscopy is an essential tool in biomedical sciences that allows specific molecules to be visualized in the complex and crowded environment of cells. The continuous introduction of new imaging techniques makes microscopes more powerful and versatile, but there is more than meets the eye. In addition to develop- ing new methods, we can work towards getting the most out of existing data and technologies. By harnessing unused potential, this work aims to increase the richness, reliability, and power of fluorescence microscopy data in three key ways: through standardization, evaluation and innovation. A universal standard makes it easier to assess, compare and analyze imaging data – from the level of a single laboratory to the broader life sciences community. We propose a data-standard for fluorescence microscopy that can increase the confidence in experimental results, facilitate the exchange of data, and maximize compatibility with current and future data analysis techniques. Cutting-edge imaging technologies often rely on sophisticated hardware and multi-layered algorithms for reconstruction and analysis. Consequently, the trustworthiness of new methods can be difficult to assess. To evaluate the reliability and limitations of complex methods, quantitative analyses – such as the one present here for the 3D SPEED method – are paramount. The limited resolution of optical microscopes prevents direct observation of macro- molecules like DNA and RNA. We present a multi-color, achromatic, cryogenic fluorescence microscope that has the potential to produce multi-color images with sub-nanometer precision. This innovation would move fluorescence imaging beyond the limitations of optics and into the world of molecular resolution. microscopy nanoscopy fluorescence cryogenic cryo-fluorescence cryoFM FM 3DSPEED SPEED standardization PSF PSF engineering achromatic dichroic multi-color super-resolution imaging imaging standard optics adaptive optics meta-data meta MetaMax calibration characterization back-projection image reconstruction pseudo-tomography model-based reconstruction chromatic aberrations cryogenic imaging 4D-PSF calibration tool Bioimaging and Biomedical Optics Biological Engineering Biomedical Devices and Instrumentation Biophysics Computer-Aided Engineering and Design Electrical and Electronics Electromagnetics and Photonics Electro-Mechanical Systems Engineering Physics Molecular Biology Nanoscience and Nanotechnology Numerical Analysis and Computation Optics Other Engineering Systems and Integrative Engineering

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