Chan Wang-Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-94). / Abstracts in English and Chinese. / TITLE PAGE --- p.i / THESIS COMMITTEE --- p.ii / ABSTRACT (ENGLISH) --- p.iii / ABSTRACT (CHINESE) --- p.v / ACKNOWLEDGEMENTS --- p.vi / TABLES OF CONTENTS --- p.vii / LIST OF FIGURES --- p.ix / LIST OF TABLES --- p.xii / Chapters / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Laser absorption spectroscopy of C2 Phillips System --- p.4 / Chapter A. --- Introduction --- p.4 / Chapter B. --- Quantum mechanics of C2 --- p.13 / Chapter C. --- Experimental details --- p.18 / Chapter D. --- Observation --- p.24 / Chapter E. --- Spectroscopic analysis --- p.30 / Chapter F. --- Discussion --- p.43 / Chapter G. --- Conclusion --- p.48 / Chapter 3 --- Computational study of O2-(rare gas) van der Waals complexes --- p.49 / Chapter A. --- Background --- p.49 / Chapter B. --- Van der Waals complexes: an overview --- p.60 / Chapter C. --- Methodology --- p.62 / Chapter D. --- Results --- p.65 / Chapter E. --- Discussion and Conclusion --- p.81 / Chapter 4 --- Concluding Remarks --- p.85 / REFERENCES --- p.87

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The present thesis is examining the forced vibrations of a circular cylinder in the low Reynolds number flow of 200. A numerical study is performed that employs an already existing algorithm developed by (Breuer 1998) and enhanced with the characteristic of the cylinder's motion by (MadaniKermani 2014) who employed the moving frame of reference method of (L. Li, Sherwin et al. 2002). The algorithm was extensively assessed for the benchmark studies of flow around a stationary circular cylinder. A new observation was made on the effect of the aspect ratio of the computational cells in the mid region of the wake. The studies so far are emphasizing on the characteristic of a dense mesh, with a small aspect ratio, in the high divergence areas in the near region of the cylinder surface, neglecting the effect of the regions away from the surface. The present study on a stationary circular cylinder flow, proved that the aspect ratio of the distant cells has a significant effect on the St number and the force coefficients. The main study of the thesis emphasizes on the lock-in region where the wake oscillates in unison with the harmonic motion of the cylinder. The study makes a new observation on the qualitative and quantitative description of the lock-in conditions. In particular, it reveals two regions of resonance and non-resonance lock-in. Despite the fact that the lock-in is achieved, when the frequency ratio is in the first part of the region away from the unity ratio, the forces are not greatly magnified. As the ratio approaches the unity the forces experience a resonance that reaches the highest value after the unity. Furthermore, the adaptation time of the flow to the motion of the cylinder is examined and extends the results of (Anagnostopoulos 2000) to the full extent of the lock-in and the non-lock-in regions. More precisely the flow strives to reach a steady state when it is in the lock-in region rather in the non-lock in cases it reaches the steady state faster. It is postulated that the adaptation time depends on both the numerical and the physical adaptation. Moreover, the force coefficients characteristic of sinusoidal behaviour in the lock-in region is attempted to be approximated by a Newton polynomial that is built by making use of the divided differences method. The amplitude of the forces is approximated by a third degree Netwon polynomial built from the results of the present thesis simulations. The use of an approximation is providing faster results ignoring the need for a full resolution of the Navier-Stokes equation.

Orientador: José Ricardo de Arruda Miranda / Banca: Wellington Monteiro Machado / Banca: Roberto Morato Fernandez / Resumo: Comprimidos são as formas farmacêuticas mais utilizadas devido a facilidade de obtenção, baixo custo e estabilidade. A liberação do fármaco contido nos comprimidos ocorre por meio do processo de desintegração. A desintegração é um processo tempo-dependente que ocorre sob ação de desintegrantes e promove a fragmentação da forma farmacêutica em partículas passíveis de serem dissolvidas e absorvidas. É um parâmetro de qualidade extremamente importante, sendo influenciada por diversos fatores, incluindo o tipo de desintegrante utilizado e a força de compressão aplicada. Desintegrantes são compostos insolúveis que atuam por diferentes mecanismos e são excipientes essenciais para a obtenção de formas farmacêuticas sólidas. Para a maioria dos desintegrantes, a penetração de água na forma farmacêutica é um fator determinante para um bom desempenho, visto que resulta no intumescimento das partículas e no desenvolvimento da força que auxilia o processo de desintegração. A determinação experimental do processo de desintegração é realizada por meio de aparato específico, no entanto, não permite uma avaliação mais acurada dos mecanismos envolvidos no processo. Desse modo, foram introduzidos alguns métodos de análise que, associados aos métodos convencionais, permitem explorar outras características do processo e avaliar a eficiência de desintegrantes bem como a relação entre a desintegração e a força de compressão aplicada. O objetivo desse trabalho foi associar a Biosusceptometria AC com dispositivos para medir a força de desintegração e a quantidade de água absorvida e, assim, avaliar a influencia de três superdesintegrantes no processo de desintegração de comprimidos obtidos com cinco níveis de compressão distintos / Abstract: Tablet dosage forms are used due to ease of production, low cost and stability. The release of the drug contained in the tablets occurs through disintegration process. Disintegration is a time-dependent process that occurs under the action of disintegrants that promotes fragmentation of the dosage form particles capable of being dissolved and absorbed. It is an extremely important quality parameter, being influenced by several factors, including the type of disintegrant used and the compression force applied. Disintegrants are insoluble compounds that act by different mechanisms and are essential excipient for achieving solid dosage form. For most disintegrants, water penetration in the pharmaceutical form is an important factor for a good performance, since it results in particles swelling and the development of force that aids the disintegration process. The experimental determination of the disintegration process is accomplished by means of specific apparatus, however, does not allow a more accurate assessment of the mechanisms involved. Thus we have introduced some analytical methods, associated with conventional methods, allowing exploring other features of the process and evaluating the effectiveness of disintegrants as well as the correspondence between disintegration and compression force applied. The objective was to associate AC Biosusceptometry with devices to measure the force of disintegration and the amount of water absorbed, and thus evaluate the influence of three superdisintegrant in the process of disintegration of tablets obtained with five different levels of compression / Mestre

Cells experience different mechanical cues from their local environment, including shear flow, forces applied by neighbouring cells, and substrate stiffness. These external signals influence cell behaviour, also in embryonic stem (ES) cells, where they could potentially affect pluripotency or differentiation. The precise effects of external forces on ES cells are confounded by forces inducing secondary changes to attachment or cell-cell signalling, which themselves can also influence cell behaviour. In this study we developed a set-up to attach cells to elastic membranes using a novel functionalisation technique, and exposed them to single or cyclic stretch. We used this method to study the mechanosensitive response of ES cells. We found that stretching caused an immediate increase in the concentration of intracellular calcium, followed by a rapid decrease in some cells. On timescales of 1 - 2 h, stretching induced an increase in the expression of the immediate and early genes, but then cells became temporarily insensitive to subsequent mechanical signals. Stretching did not have a substantial impact on pluripotency and differentiation, as we showed using gene expression studies and a Rex1 reporter. To study how ES cells' susceptibility to mechanical signals depended on media condition, stretch duration and stretch type, we performed RNA sequencing and used gene ontology techniques to investigate the involvement of specific pathways. We found that forces have a broad impact on the overall transcriptome that is highly culture media-dependent. However, a core transcriptional response, including the biosynthesis of membrane components and stress pathways, was largely preserved across the different conditions. We supplemented our experimental findings with a conceptual model of force propagation in disordered environments, such as the nucleus of a cell. Using computational simulations, we studied how the large-scale behaviour of a disordered system depends on the microscopic structure. Contrary to common wisdom, we showed that disordered systems exhibit both positive and negative Poisson's ratios with equal probability. Overall, on short timescales, stretching affected ES cells' calcium concentration and transcription. On longer timescales, ES cells' response was small in magnitude but broad in scope, with limited effects on pluripotency. As such, our results suggest that mechanosensitivity in ES cells is mediated primarily by tissue-wide changes to morphology and attachment.

This project is both a wartime biography and an examination of the American effort in France during the First World War. At its core, the narrative follows the military career of Major General James G. Harbord. His time in France saw Harbord serve in the three main areas of the American Expeditionary Forces: administration, combat, and logistics. As chief of staff to AEF commander General John J. Pershing, Harbord was at the center of the formation of the AEF and the development of its administrative policies. He organized and managed the AEF General Staff and served as Pershing's most trusted subordinate. In May of 1918, Harbord transferred to the fighting line, taking over command of the 4th "Marine" Brigade. During his time with the 4th Brigade, and later as commander of the 2nd Division, Harbord played a significant part in the battles of Belleau Wood and Soissons. A dedicated supporter of Pershing's tactics of "open" warfare, Harbord's failings as a combat commander showed the limits of American tactical experience. For the final four months of the war, Harbord took over control of the AEF's logistical system, the Services of Supply. Though he proved an able administrator, the American supply system approached total collapse in the fall of 1918, and was prevented only by the signing of the Armistice. In all three of these roles, Harbord embodied the emergence of the military manager in the American army. The First World War illustrates that war had grown so large and complex that it required officers whose primary talents lay not in leading men in combat, but in the areas of administration and management of large bureaucratic organizations. James Harbord was one of the first, and best, examples of this new type of officer.

In the past two decades much effort has been put in the characterization of the mechanical and surface properties at the nano-scale in order to conceive reliable N/MEMS (Nano and Micro ElectroMechanical Systems) applications. Techniques like nanoindentation, nanoscratching, atomic force microscopy have become widely used to measure the mechanical and surface properties of materials at sub-micro or nano scale. Nevertheless, many phenomena such us pile-up and pop-in as well as surface anomalies and roughness play an important role in the accurate determination of the materials properties. The first goal of this report is to study the infulence of these sources of data distortion on the experimental data. The results are discussed in the first experimental chapter. On the other hand, conceptors would like to adapt/tune the mechanical and surface properties as a function of the required application so as to adapt them to the industrial need. Coatings are usually applied to materials to enhance performances and reliability such as better hardness and elastic modulus, chemical resistance and wear resistance. In this work, the magnetron sputtering technique is used to deposit biocompatible thin layers of different compositions (titanium carbide, titanium nitride and amorphous carbon) over a titanium substrate. The goal of this second experimental part is the study of the deposition parameters influence on the resulting mechanical and surface properties. New materials such as nanocrystal superlattices have recently received considerable attention due to their versatile electronic and optical properties. However, this new class of material requires robust mechanical properties to be useful for technological applications. In the third and last experimental chapter, nanoindentation and atomic force microscopy are used to characterize the mechanical behavior of well ordered lead sulfide (PbS) nanocrystal superlattices. The goal of this last chapter is the understanding of the deformation process in order to conceive more reliable nanocrystal superlattices.

A variety of behavioural tests were used to examine both sensory and motor function of freely behaving unilaterally spinal cord-injured and uninjured rats. The first experiment was designed to determine whether sensory and motor differences existed between uninjured Fischer, Lewis, Long-Evans, Sprague-Dawley and Wistar rats using endpoint, quantitative kinematic, and kinetic measurements. The second experiment examined differences in sensorimotor responses to cervical spinal cord hemisection in Lewis, Long-Evans and Wistar rats. For the third experiment, reflex and locomotor abilities of unilateral cervical or thoracic spinal cord hemisected Long-Evans rats were determined using endpoint, semi-quantitative kinematic, and kinetic measurements. The fourth experiment was designed to investigate the importance of the rubrospinal tract and ascending dorsal column pathways to overground locomotion. This experiment was conducted to help explain the behavioural observations made following cervical spinal cord hemisection. Furthermore, this experiment examined the effects of combined unilateral rubrospinal and dorsal column injury on overground locomotion using endpoint and kinetic measurements. Finally, the fifth experiment set out to investigate the contribution of tracts running in the ventrolateral spinal cord on overground locomotion in freely behaving Long-Evans rats. These animals were assessed using endpoint and kinetic measurements. The results of these studies revealed that motor and sensory functions are not similar for all uninjured strains of rats. Specifically, Fischer rats tend to have considerable differences in their morphological features and sensorimotor abilities compared to the other strains examined. Results from the other experiments indicate that adult freely behaving female rats develop a characteristic gait when pathways important for locomotion are injured unilaterally, regardless of strain. The rubrospinal tract and ascending dorsal column pathways appear to be important for both skilled and flat-ground locomotion as well as forelimb use while rearing. Pathways traveling within the ventrolateral pathway, however, are not necessary or sufficient for locomotion or limb useage while rearing when injured by themselves. Animals with ventrolateral spinal funiculus injuries regain normal forelimb use and skilled locomotor abilities. Injury to the ventrolateral spinal funiculus, however, results in mild (compared to rubrospinal and dorsal column injured animals) yet long-lasting locomotor changes based on ground reaction force determination. These findings are in agreement with the current opinion that there is a substantial amount of functional redundancy of pathways traveling in the ventral and ventrolateral funiculi.

A variety of behavioural tests were used to examine both sensory and motor function of freely behaving unilaterally spinal cord-injured and uninjured rats. The first experiment was designed to determine whether sensory and motor differences existed between uninjured Fischer, Lewis, Long-Evans, Sprague-Dawley and Wistar rats using endpoint, quantitative kinematic, and kinetic measurements. The second experiment examined differences in sensorimotor responses to cervical spinal cord hemisection in Lewis, Long-Evans and Wistar rats. For the third experiment, reflex and locomotor abilities of unilateral cervical or thoracic spinal cord hemisected Long-Evans rats were determined using endpoint, semi-quantitative kinematic, and kinetic measurements. The fourth experiment was designed to investigate the importance of the rubrospinal tract and ascending dorsal column pathways to overground locomotion. This experiment was conducted to help explain the behavioural observations made following cervical spinal cord hemisection. Furthermore, this experiment examined the effects of combined unilateral rubrospinal and dorsal column injury on overground locomotion using endpoint and kinetic measurements. Finally, the fifth experiment set out to investigate the contribution of tracts running in the ventrolateral spinal cord on overground locomotion in freely behaving Long-Evans rats. These animals were assessed using endpoint and kinetic measurements. The results of these studies revealed that motor and sensory functions are not similar for all uninjured strains of rats. Specifically, Fischer rats tend to have considerable differences in their morphological features and sensorimotor abilities compared to the other strains examined. Results from the other experiments indicate that adult freely behaving female rats develop a characteristic gait when pathways important for locomotion are injured unilaterally, regardless of strain. The rubrospinal tract and ascending dorsal column pathways appear to be important for both skilled and flat-ground locomotion as well as forelimb use while rearing. Pathways traveling within the ventrolateral pathway, however, are not necessary or sufficient for locomotion or limb useage while rearing when injured by themselves. Animals with ventrolateral spinal funiculus injuries regain normal forelimb use and skilled locomotor abilities. Injury to the ventrolateral spinal funiculus, however, results in mild (compared to rubrospinal and dorsal column injured animals) yet long-lasting locomotor changes based on ground reaction force determination. These findings are in agreement with the current opinion that there is a substantial amount of functional redundancy of pathways traveling in the ventral and ventrolateral funiculi.

Mathematical musculoskeletal modeling and simulation provide a means for proactive injury prevention. To be effective, these models must physiologically replicate shoulder function. Although several muscle force prediction (MFP) shoulder models exist, few have attempted to integrate the force contributions of ligaments, especially the glenohumeral ligaments. The purpose of the current study was to integrate seven shoulder ligaments into an existing computational shoulder model, and analyze both individual ligament characteristics and the influence on the model outputs. Using data from the literature, seven shoulder ligaments were integrated into the model: the costoclavicular, conoid, trapezoid, coracohumeral, superior glenohumeral, middle glenohumeral, and inferior glenohumeral. 10 subjects performed isometric exertions in 56 posture-force combinations. Upper body posture and hand force collected were used as inputs for three different model versions; No-Ligaments (NL) included, Glenohumeral-Ligaments (GH) included, and All-Ligaments (AL) included. Electromyographic (EMG) signals from 11 muscle sites were used for comparison with model MFPs. The primary analysis focused on the differences between the GH and NL versions. Normalized EMG amplitudes were plotted against normalized MFPs from both models. Ligament effects on model outputs were measured by comparing changes in correlation between EMG and MFP, changes in slopes regression lines relating EMG to MFP, and the frequency of zero-force prediction by the model. Paired Student’s t-tests were used to measure significant differences. Results showed significant correlations (Pearson product) between EMG amplitude and MFP in the lower trapezius and infraspinatus muscles (p<0.01). No significant differences were found in r-values for these muscles between the NL and GH model. Slopes of regression lines decreased when GH ligaments were added, while the change in zero-force predictions varied by muscle. This study highlights the sensitivity of musculoskeletal models to the inclusion of ligament forces. Though correlations did not change, decreases in slope indicate increased force prediction by the GH model. Though zero-force predictions for some muscles increased, the results from those that decreased suggest muscles are active in postures where they were originally believed to be inactive. This finding suggests that inclusion of GH ligaments into our model may help predict antagonist muscle activity. However, further research is required.