Hui, Fan Fong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 153-181). / Abstract also in Chinese. / Acknowledgements --- p.ii / Abstract --- p.iii / Abbreviations --- p.vii / Table of Contents --- p.ix / List of Tables --- p.xv / List of Tables --- p.xv / List of Figures --- p.xvi / Major Conference Presentations --- p.xix / Publications in Preparation --- p.xxii / Chapter Chapter 1 --- Study Background --- p.1 / Chapter 1. --- Introduction --- p.2 / Chapter 1.1. --- Spinal Deformities --- p.2 / Chapter 1.1.1. --- Treatment --- p.2 / Chapter 1.2. --- Spinal fusion --- p.4 / Chapter 1.2.1. --- Gold Standard of Spinal Fusion --- p.4 / Chapter 1.2.2. --- Decortication in Spinal Fusion --- p.4 / Chapter 1.2.3. --- Autograft in Spinal Fusion --- p.4 / Chapter 1.2.4. --- Local Factors Influencing Spinal Fusion --- p.5 / Chapter 1.2.5. --- Ultimate Goals of Spinal Fusion --- p.7 / Chapter 1.2.6. --- Limitations of Spinal fusion --- p.7 / Chapter 1.3. --- Alternatives of Different Components for Enhancing Spinal Fusion / Chapter 1.3.1. --- Bone Graft Substitute --- p.9 / Chapter 1.3.2. --- Bioactive Factors --- p.15 / Chapter 1.4. --- Limitations of the Alternative Methods in Spinal Fusion Enhancement --- p.19 / Chapter 1.4.1. --- BMPs --- p.19 / Chapter 1.4.2. --- Gene Therapy --- p.20 / Chapter 1.4.3. --- Biophysical Stimulation --- p.20 / Chapter 1.5. --- Recent Methods in Enhancing Spinal Fusion --- p.21 / Chapter 1.5.1. --- Low Intensity Pulsed Ultrasound --- p.21 / Chapter 1.5.2. --- Mesenchymal Stem Cells in Spinal Fusion --- p.24 / Chapter 1.6. --- Conclusion --- p.26 / Chapter Chapter 2 --- "Hypothesis, Objectives and Plan of Study" --- p.29 / Chapter 2. --- "Hypothesis, Objectives and Plan of Study" --- p.30 / Chapter 2.1 --- Study Hypothesis --- p.31 / Chapter 2.2 --- Study Objectives --- p.31 / Chapter 2.3 --- Plan of Study --- p.32 / Chapter 2.3.1 --- For First Objective --- p.32 / Chapter 2.3.2 --- For Second Objective --- p.32 / Chapter 2.3.3 --- For Third Objective --- p.33 / Chapter Chapter 3 --- In vitro Study of Effect of Low Intensity Pulsed Ultrasound on Mesenchymal Stem Cells --- p.34 / Chapter 3.1. --- Introduction --- p.35 / Chapter 3.2. --- Materials and Methods --- p.36 / Chapter 3.2.1. --- Experimental Animal --- p.36 / Chapter 3.2.2. --- Materials and Reagents --- p.36 / Chapter 3.2.2.1. --- Dulbecco，s Modified Eagle Medium (DMEM) --- p.36 / Chapter 3.2.2.2. --- Phosphate Buffered Saline (PBS) --- p.37 / Chapter 3.2.2.3. --- Osteogenic Medium (OS) --- p.37 / Chapter 3.2.2.4. --- Alkaline Phosphatase (ALP) Buffer --- p.37 / Chapter 3.2.2.5. --- ALP Substrate Buffer --- p.38 / Chapter 3.2.2.6. --- MTT Stock Solution --- p.38 / Chapter 3.2.2.7. --- MTT Working Solution --- p.38 / Chapter 3.2.2.8. --- Lysis buffer --- p.38 / Chapter 3.2.2.9. --- Alkaline Phosphatase (ALP) Working Reagents --- p.39 / Chapter 3.2.3. --- Isolation of Bone Marrow Derived Mesenchymal Stem Cells (BM derived MSCs) --- p.39 / Chapter 3.2.4. --- In vitro Low Intensity Pulsed Ultrasound Treatment --- p.40 / Chapter 3.2.4.1. --- In vitro LIPUS Devices --- p.40 / Chapter 3.2.4.2. --- Treatment Procedure and Experimantal Groupings --- p.40 / Chapter 3.2.5. --- Effect of LIPUS on Cell Viability and Osteogenesis in bone marrow derived-MSCs --- p.41 / Chapter 3.2.5.1. --- Cell Viability Assay --- p.41 / Chapter 3.2.5.2. --- Alkaline Phosphatase (ALP) Enzyme Activity --- p.42 / Chapter 3.2.5.3. --- Cell Morphology and Alkaline Phosphatase Cytochemistry --- p.42 / Chapter 3.2.6. --- Statistical Analysis --- p.43 / Chapter 3.3. --- Results --- p.43 / Chapter 3.3.1. --- Morphology --- p.43 / Chapter 3.3.2. --- Total Number of Viable Cells --- p.44 / Chapter 3.3.3. --- ALP Activity Absorbance --- p.44 / Chapter 3.3.4. --- ALP staining --- p.45 / Chapter 3.3.5. --- Qualitative Analysis --- p.45 / Chapter 3.3.6. --- Quantitative Analysis --- p.46 / Chapter 3.4. --- Discussion --- p.46 / Chapter 3.4.1. --- LIPUS have No Enhancing Effect on Proliferation of MSCs in Basal Medium Nor Osteogenic Medium --- p.47 / Chapter 3.4.2. --- LIPUS Stimulate Proliferation of MSCs in Early Period --- p.49 / Chapter 3.4.3. --- LIPUS Further Enhanced Osteogenesis of MSCs in Osteogenic Medium --- p.49 / Chapter 3.4.4. --- 10 mins LIPUS treatment for 7 days can positively enhance osteogenic differentiation --- p.50 / Chapter 3.4.5. --- Optimum Conditions of LIPUS was Cell Type Dependent --- p.51 / Chapter 3.4.6. --- LIPUS Promoted Osteogenesis in MSCs through Accelerated Mineralization --- p.52 / Chapter Chapter 4 --- Enhancement of Posterior Spinal Fusion The Effect of Tissue-Engineered MSC and Calcium Phosphate Ceramic composite treated with LIPUS in Vivo --- p.68 / Chapter 4.1. --- Introduction --- p.69 / Chapter 4.1.1. --- TCP Biomaterials --- p.70 / Chapter 4.2. --- Materials and Methods --- p.71 / Chapter 4.2.1. --- Materials and Reagents --- p.71 / Chapter 4.2.2. --- Preparation of MSC Derived Osteogenic Cells-tricalcium Phosphate Ceramics Composite --- p.73 / Chapter 4.2.3. --- Posterior Spinal Fusion Surgery --- p.74 / Chapter 4.2.4. --- In vivo LIPUS treatment --- p.75 / Chapter 4.2.5. --- Assessment of Fusion Mass --- p.76 / Chapter 4.2.6. --- Histology --- p.77 / Chapter 4.2.7. --- Statistical Analysis --- p.79 / Chapter 4.3. --- Results --- p.79 / Chapter 4.3.1. --- Fusion by Manual Palpation --- p.79 / Chapter 4.3.2. --- pQCT Analysis --- p.80 / Chapter 4.3.3. --- Histological Analysis --- p.81 / Chapter 4.4. --- Discussion --- p.85 / Chapter 4.4.1. --- Summary of the Findings from Different Assessment Methods --- p.85 / Chapter 4.4.2. --- Addition of MSCs to TCP ceramic in Spinal Fusion --- p.87 / Chapter 4.4.3. --- The Needs of Differentiated MSC in Spinal Fusion --- p.89 / Chapter 4.4.4. --- bFGF Masked the Effect of OS in MSC --- p.91 / Chapter 4.4.5. --- LIPUS Enhanced Bone Formation --- p.95 / Chapter 4.4.6. --- LIPUS Enhanced Bone Formation through Mineralization --- p.96 / Chapter 4.4.7. --- LIPUS Enhanced Spinal Fusion through Bone Remodeling-induced Fusion Mass --- p.97 / Chapter 4.4.8. --- LIPUS Enhanced Bone Formation through Endochondral Ossification --- p.99 / Chapter Chapter 5 --- In Vivo Monitoring of Spinal Fusion in Animal Model with High-resolution Peripheral Quantitative Computed Tomography-A New Pilot Study --- p.122 / Chapter 5.1. --- Introduction --- p.123 / Chapter 5.2. --- Materials and Methods --- p.124 / Chapter 5.2.1. --- Animal Groupings --- p.124 / Chapter 5.2.2. --- Preparation of MSC Derived Osteogenic Cells-tricalcium Phosphate Ceramics Composite --- p.124 / Chapter 5.2.3. --- Posterior Spinal Fusion Operation Procedures --- p.125 / Chapter 5.2.4. --- LIPUS treatment --- p.125 / Chapter 5.2.5. --- High-resolution Peripheral Quantitative Computed Tomography …- --- p.125 / Chapter 5.2.6. --- Analysis with HR-pQCT --- p.126 / Chapter 5.3. --- Result --- p.128 / Chapter 5.3.1. --- Qualitative Observations from HR-pQCT Images --- p.128 / Chapter 5.3.2. --- Quantitative Analysis --- p.129 / Chapter 5.4. --- Discussion --- p.130 / Chapter Chapter 6 --- "Overall Summary, Discussion and Conclusion" --- p.140 / Chapter 6.1. --- Overall Summary and Discussion --- p.141 / Chapter 6.2. --- Limitations and Further Studies --- p.145 / Chapter 6.3. --- Conclusions --- p.147 / Chapter 6.4. --- Summary Flowchart of the whole thesis --- p.148 / References --- p.153

Includes bibliography (leaves 249-291). / xxiv, 291, [52] leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Discusses and evaluates the role of intra-operative ultrasound in colorectal surgery ; techniques of laparoscopic surgery and the impact on the incidence of hypothermia during surgery ; advanced prognostic techniques in colorectal cancer ; the impact of ambulatory anorectal surgery ; and, the potential of an information video to decrease the anxiety of patients through imparting essential information to patients. / Thesis (M.D.)--University of Adelaide, Dept. of Surgery, 1999

Conventional contact ultrasonic methods suffer from large variability, which is known to originate from a number of sources such as coupling variability, and the surface roughness at the transducer/specimen interface. The inherently small higherharmonic signals can be significantly influenced by the changes in contact conditions, especially in nonlinear ultrasonic measurements. For this reason, the noncontact generation and detection techniques are very attractive. This research first focuses on the optical generation of tone-burst surface acoustic waves in a metallic specimen. Two methods that use laser light as an optical source are compared for generating surface acoustics waves in the 5 MHz range. Both the shadow mask and diffraction grating are used to convert a laser pulse to a tone-burst signal pattern on the specimen. The generated signals are detected by a wedge transducer at a fixed location and then the harmonic contents in the generated signals and the repeatability of the methods are evaluated. Finally, the developed method is used to characterize the material nonlinearity of aluminum (Al 6061) and steel (A36). The results showed repeatable measurements for ablative signal excitation on aluminum.

Pulsed ultrasound Doppler velocimetry proved to be capable of measuring velocities accurately (relative error less than 0.5 percent). In this research, the limitations of the method are investigated when measuring: in channels with a small thickness compared to the transducer diameter, at low velocities and in the presence of a flow reversal area. A review of the fundamentals of pulsed ultrasound Doppler velocimetry reveals that the accuracy of the measured velocity field mainly depends on the shape of the acoustic beam through the flow field and the intensity of the echo from the incident particles where the velocity is being measured. The ultrasonic transducer turned out to be most critical component of the system. Fundamental limitations of the method are identified. With ultrasonic beam measurements, the beam shape and echo intensity is further investigated. In general, the shape of the ultrasonic beam varies depending on the frequency and diameter of the emitter as well as the characteristics of the acoustic interface that the beam encounters. Moreover, the most promising transducer to measure velocity profiles in small channels is identified. Since the application of pulsed ultrasound Doppler velocimetry often involves the propagation of the ultrasonic burst through Plexiglas, the effect of Plexiglas walls on the measured velocity profile is analyzed and quantified in detail. The transducers ringing effect and the saturation region caused by highly absorbing acoustic interfaces are identified as limitations of the method. By comparing measurement results in the small rectangular channel to numerically calculated results, further limitations of the method are identified. It was not possible to determine velocities correctly throughout the whole channel at low flow rates, in small geometries and in the flow separation region. A discrepancy between the maximum measured velocity, velocity profile perturbations and incorrect velocity determination at the far channel wall were main shortcomings. Measurement results are improved by changes in the Doppler angle, the flow rate and the particle concentration. Suggestions to enhance the measurement system, especially its spatial resolution, and to further investigate acoustic wave interactions are made.

The focus of this Ph.D. thesis research is a new piezoelectrically driven micromachined ultrasonic atomizer concept that utilizes fluid cavity resonances in the 15 MHz range along with acoustic wave focusing to generate the pressure gradient required for droplet or jet ejection. This ejection technique exhibits low-power operation while addressing the key challenges associated with other atomization technologies including production of sub-5 um diameter droplets, low-temperature operation, the capacity to scale throughput up or down, and simple, low-cost fabrication. This thesis research includes device development and fabrication as well as experimental characterization and theoretical modeling of the acoustics and fluid mechanics underlying device operation. The main goal is to gain an understanding of the fundamental physics of these processes in order to achieve optimal design and controlled operation of the atomizer. Simulations of the acoustic response of the system for various device geometries and different ejection fluid properties predict the resonant frequencies of the device and confirm that pressure field focusing occurs. High-spatial-resolution stroboscopic visualization of fluid ejection under various operating conditions is used to investigate whether the proposed atomizer is capable of operating in either the discrete-droplet or continuous-jet mode. The results of the visualization experiments combined with a scaling analysis provide a basic understanding of the physics governing the ejection process and allow for the establishment of simple scaling laws that prescribe the mode (e.g., discrete-droplet vs. continuous-jet) of ejection. In parallel, a detailed computational fluid dynamics (CFD) analysis of the fluid interface evolution and droplet formation and transport during the ejection process provides in-depth insight into the physics of the ejection process and determines the limits of validity of the scaling laws. These characterization efforts performed in concert with device development lead to the optimal device design. The unique advantages enabled by the developed micromachined ultrasonic atomizer are illustrated for challenging fluid atomization examples from a variety of applications ranging from fuel processing on small scales to ultra-soft electrospray ionization of biomolecules for bioanalytical mass spectrometry.

This research investigates how ultrasonic damage monitoring in civil structures can be implemented on a small, battery-powered, self-contained device. The device is intended for the continuous monitoring of surface breaking cracks in steel using Rayleigh waves. This study in detail presents the challenges that are to be considered for the intended ultrasonic monitoring, with the objective to provide a foundation for the future development of a fully autonomously operating device. The study proposes a suitable hardware and software layout, and a prototype device is built using a digital signal processor, a commercial wireless transceiver, and custom amplification circuits. With the help of two narrowband ultrasonic contact transducers in a pitch-catch setup and appropriate contact wedges, the wave field that arises from scattering of an incident tone burst wave at a crack is measured. A data analysis algorithm extracts wave burst signals from the acquired output in order to minimize the data that is to be transmitted. Additional compression of the data and the implementation of a communication protocol allow for a reliable and efficient wireless transmission. In order to demonstrate the feasibility of the proposed approach, measurements of notches in a steel plate with different depths are taken. Measurement results from experiments with commercial ultrasonic equipment are compared to measurements taken with the prototype device. The influence of the sampling distortions on the signals are analyzed. The scope of this study is limited to a qualitative analysis of the experimental results; quantitative methods to determine the dimensions of a crack or notch from the measured data are not included. The research conducted demonstrates that taking ultrasonic measurements with a small, self-contained device is feasible. Comparison of frequency-based to time-based signal analysis methods yields that frequency-based methods are preferable, as they are affected less by sampling effects. The experimental results show that the intended ultrasonic examination technique can be used for qualitative damage assessment. The knowledge gained in this study contributes to improving the safety of civil infrastructure. Continuous local damage monitoring as proposed helps to detect critical conditions in-time, and to take countermeasures to avoid catastrophic failures.

Recent theoretical and experimental studies in a wide range of applications (ultrasonics, underwater acoustics, seismicoe) have demonstrated that Green's functions (impulse responses) can be extracted from cross-correlation of diffuse fields using only passive sensors. The technique, whose validity is supported by a physical argument based on time-reversal invariance, effectively uses a correlation process between the point source and points located in the focal zone. Indeed, the coherent noise source distributions can be considered as a timereversal mirror and the cross-correlation operations gives the field measured at one receiver after refocusing on the other receiver. Passive-only reconstruction of coherent Lamb waves (80-200 kHz) in an aluminum plate and thickness comparable to aircraft fuselage and wing panels will be presented. In particular, the influence of the noise source characteristics (location, frequency spectrum) on the signal-to-noise ratio the emerging coherent waveform will be investigated using a scanning laser Doppler velocimeter. This study suggests the potential for a structural health monitoring method for aircraft panels based on passive ultrasound imaging reconstructed from diffuse fields.

Ultrasonic Consolidation (UC) is a solid state additive manufacturing process which fabricates three-dimensional objects by ultrasonically joining metal foils together, layer-bylayer, to form a solid part. A wide range of materials can be used to fabricate parts by UC and products with complex internal geometry can be generated by shaping the crosssection throughout the build using Computer Numerically Controlled (CNC) milling. As a result of its ability to embed various secondary materials and fibres in metal matrices, UC has emerged as a potential method of fabricating multi-functional materials and structures.

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to evaluate and compare the debridement efficacy of the EndoActivator (Dentsply Tulsa Dental, Tulsa, OK) versus the Ultrasonic Bypass system (Vista Dental) following hand-rotary instrumentation in anterior teeth. Sixty extracted human, maxillary anterior teeth were randomly assigned to three groups. Teeth were instrumented using (ISO k-flex) hand files and EndoSequence nickel-titanium rotary files (Brasseler, Savannah, GA) to a size 40/.06 taper. Group 1 served as the control group and had no additional treatment performed. Groups 2 and 3 were subjected to a final irrigating regimen that consisted of 6-percent sodium hypochlorite for a 1- minute duration. For group 2 the irrigation solution was activated for 1 minute using the EndoActivator system (DENTSPLY). For group 3, the irrigation solution was activated for 1 minute using the Ultrasonic Bypass System (Vista Dental). The teeth were then sectioned longitudinally and each half was divided into three equal parts 3 mm from the anatomic apex. The sample with the most visibly identifiable section of the apex was used for SEM evaluation. A scoring system to measure the efficacy of debris removal was utilized to quantify the results. Statistical analysis was performed using the Kruskal- Wallis test. If the overall test is significant, a Wilcoxon Rank Sum tests was used to compare each pair of groups. The results of this study indicate that both the EndoActivator and Ultrasonic Bypass groups had a smaller percentage of canal space occupied by smear layer and debris when compared with the control group at all three levels. This difference was statistically significant for the Ultrasonic Bypass System when compared with the control at both the coronal and middle thirds of the samples evaluated. This difference was not statistically significant in the apical third. When compared with the EndoActivator, the Ultrasonic Bypass System produced cleaner canals in the coronal and middle thirds, with the difference being statistically significant in the middle third only. These results of this research support the use of either of these two devices when compared with the controls. Smear layer removal and debridement efficacy was greatly increased when using either sonic or ultrasonic activation of sodium hypochlorite. More research is warranted concerning these two devices. Examining the antimicrobial efficacy with the use of these two devices could lend additional validation to their use in non-surgical endodontic therapy.

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