Hong, Wei = 膠體玻璃化相變的實驗及理論研究 / 洪偉. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 89-91). / Abstracts in English and Chinese. / Hong, Wei = Jiao ti bo li hua xiang bian de shi yan ji li lun yan jiu / Hong Wei. / Abstract --- p.i / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Experimental background --- p.2 / Chapter 1.1.1 --- What is a colloidal system? --- p.2 / Chapter 1.1.2 --- Single particle diffusion --- p.5 / Chapter 1.1.3 --- Inter-particle interaction --- p.9 / Chapter 1.1.4 --- Colloidal phase transition --- p.14 / Chapter 1.2 --- Glass transition --- p.16 / Chapter 1.2.1 --- Vibrational modes --- p.18 / Chapter 1.2.2 --- Dynamics --- p.21 / Chapter 2 --- Experimental setup and methods --- p.29 / Chapter 2.1 --- Sample and setup --- p.29 / Chapter 2.1.1 --- Sample preparation --- p.29 / Chapter 2.1.2 --- Setup --- p.32 / Chapter 2.2 --- Resolution enhancement --- p.36 / Chapter 2.2.1 --- Alignment --- p.36 / Chapter 2.2.2 --- Lens resolution --- p.37 / Chapter 2.2.3 --- Lens combination --- p.38 / Chapter 2.2.4 --- LED light source and filter --- p.39 / Chapter 2.3 --- Image preprocessing --- p.42 / Chapter 2.3.1 --- Background subtraction --- p.42 / Chapter 2.3.2 --- Noise filter --- p.43 / Chapter 2.3.3 --- Particle recognition and tracking --- p.45 / Chapter 2.3.4 --- Dedrift --- p.47 / Chapter 3 --- Measurement --- p.50 / Chapter 3.1 --- Dynamical characteristics --- p.50 / Chapter 3.1.1 --- Mean squared displacement --- p.50 / Chapter 3.1.2 --- Diffusion coefficient versus area fraction --- p.56 / Chapter 3.2 --- Structural characteristics --- p.58 / Chapter 3.2.1 --- Pair correlation function --- p.58 / Chapter 3.2.2 --- Cluster statistics --- p.62 / Chapter 4 --- Dynamical heterogeneity and structural properties --- p.67 / Chapter 4.1 --- Dynamical heterogeneity --- p.67 / Chapter 4.2 --- Structural properties --- p.71 / Chapter 4.2.1 --- The general picture --- p.71 / Chapter 4.2.2 --- Identification of the slow particles --- p.72 / Chapter 4.2.3 --- Growing clusters of slow particles --- p.80 / Chapter 5 --- Discussion --- p.81 / Chapter 5.1 --- Percolation model --- p.81 / Chapter 6 --- Summary and conclusion --- p.87 / Bibliography --- p.89

Capture of wildlife often leads to high animal mortality. In many species, capture is associated with development of a high body temperature. This stress-induced hyperthermia appears to form an integral part of capture-related mortalities, since it occurs before, during and after exposure to capture. I used two wildlife species, impala and blesbok, and exposed them to darting and net capture so as to investigate thermal and haematological changes that occur during capture. We implanted the animals with temperature-sensitive data loggers within the abdominal cavity (for core body temperature) and caudal aspect of the thigh (for muscle temperature). Activity loggers were tethered to the abdominal wall to measure locomotor activity. Blood samples were taken after capture when the animal became recumbent and another sample 10 minutes after the first sample in order to determine haematological changes. Impala had higher abdominal body temperatures during net capture in comparison to darting, whereas blesbok abdominal body temperatures did not differ between capture methods. Different species and individuals of the same species respond differently to various capture procedures. However, I found that irrespective of the capture event or whether impala or blesbok were captured, human presence before capture caused abdominal body temperatures to rise. Similar to thermal responses, there also was high variability between individuals in terms of blood variable concentrations used to quantify physiological responses to capture. Overall, blood variable changes (total protein, sodium, lactate, haematocrit, noradrenaline, adrenaline, potassium, creatine phosphokinase, pH) were similar for impala and blesbok in response to the two capture procedures. Cortisol values in blesbok however showed a greater response during darting whereas impala showed a greater response during net capture. Similarly, osmolality values showed a greater response during net capture whereas impala showed a greater response during darting. Both the species showed that sodium and lactate correlated positively as well as noradrenaline and adrenaline correlated positively. The correlation between two variables allows us to measure only one of the variables, predicting the change of another. Unpredictable differences in thermal and blood variable measurements of impala and blesbok between different capture procedures did not allow me to correlate the thermal responses after a capture event to stress-related blood variables. The issue of obtaining a practical and accurate measurement of the hyperthermic response during capture also often arises. Rectal temperature is currently the method of choice to determine body temperature in the field. I aimed to investigate whether muscle temperature measurement can be used as an alternative body temperature measurement in the field. When abdominal core body temperatures were high, muscle temperature measurements were close to and even slightly higher than the abdominal body temperature measurements in both the species. However, low abdominal body temperatures, muscle temperature measurements were at lower and much less accurate in predicting abdominal body temperatures. Muscle temperatures can therefore predict abdominal body temperatures with sufficient accuracy during a capture event, since animals respond to capture with elevated body temperatures thus increasing the similarity between the abdominal and muscle temperature measurements measured. One potential problem with muscle temperature, is that it may reflect exercise-induced temperature increases during capture, independently of a rise in abdominal body temperature. I found that the rise in muscle temperature was not only a result of the increase in activity during a capture event but rather as a result of stress-induced hyperthermia. The increase in activity only contributes to the overall hyperthermia of the animal. The degree to which stress-induced hyperthermia contributes to mortality during capture is unclear. During my study, five impala died unexpectedly. Four impala died during the first trial while the fifth impala died before the completion of the last trial. I therefore compared the hyperthermic and haematological changes in surviving and non-surviving individuals. Both non-surviving and surviving impala in my study showed a rise in abdominal body temperature during the capture however the highest abdominal body temperatures occurred in individuals in both the surviving and non-surviving group. Very high abdominal body temperatures greater than 41ºC and 43ºC occurred in individuals of both the non-surviving and surviving animals, respectively. Some animals with an abdominal body temperature of 43ºC, therefore survived whereas other individuals died when experiencing abdominal body temperature of less than 41ºC. Blood variable responses (Creatine phosphokinase, glucose, potassium, calcium, sodium, lactate, osmolality, noradrenaline, adrenaline, pH) of the non-surviving individuals showed high values in comparison to the blood variable measurements of the surviving group. The blood variable measurements were however sampled late which will affect the measurements but can still be used to predicted mortality in the non-surviving impala. The blood variable measurements therefore were associated with mortality in the non-surviving impala. In conclusion, whether stress-induced hyperthermia can be used as a sole measure to identify a compromised individual during a capture event and concomitantly enable us to give appropriate treatment is unclear. It is evident from my study that capture induced a hyperthermic response in excitable impala as well as in the much less excitable blesbok. My study is one of few systematic studies on capture stress and shows that body temperature used in conjunction with other parameters may be useful in estimating the degree of stress in captured animals, and thus predicting likelihood of mortality or morbidity. My study also revealed that muscle temperature, possibly measured in the field by a needle-stab method, may provide an index of core body temperature.

Digitized by Kansas Correctional Industries

L’objectif de ce travail vise, à partir d’un modèle mésoscopique basé sur les automates cellulaires, qui prend en compte un petit nombre de processus simples, à interpréter les simulations numériques obtenues afin de mieux appréhender la complexité de la corrosion. Dans la première partie de ce mémoire, le modèle est appliqué à deux cas : un métal protégé par une couche isolante présentant un défaut et un métal recouvert d’une couche d’oxyde. Les réactions anodiques et cathodiques simulées peuvent se faire soit sur un même site (réactions localisées) soit sur deux sites différents (réactions spatialement séparées). L’étude des réactions localisées montre le détachement d’îlots métalliques au cours de la corrosion. Ces résultats correspondent à un phénomène mis en évidence expérimentalement l’effet chunk, responsable de déviations à la loi de Faraday. Il est montré que la vitesse effective de corrosion est amplifiée par la production des îlots résultant d’un couplage corrosion-érosion. Les réactions anodiques et cathodiques spatialement séparées sont ensuite étudiées montrant l’influence de la diffusion des espèces acido-basiques dans l’électrolyte et mettant en évidence, un régime initial où la solution reste homogène, suivi d’un régime limité par la diffusion où apparaissent des hétérogénéités chimiques engendrant des hétérogénéités physiques (rugosité du front). Le couplage entre les phénomènes chimiques et morphologiques est clairement démontré. Enfin dans une dernière partie, nous nous sommes attachés à mettre en évidence expérimentalement les déviations à la loi de Faraday dans le cas de la corrosion du zinc en milieu acide sulfurique. / The aim of this study is, using a mesoscopic model based on cellular automata and taking into account a small number of simple processes, to explain numerical simulations obtained in order to better understand the complexity of corrosion. In the first part of this work, the model is used to simulate corrosion in a defect of material protected by an insulating layer and on a metal covered by an oxide layer. Anodic and cathodic reactions simulated in the model can take place in the same site (localized reactions) or in two different (spatially separated reactions) sites. Study of localized reactions shows the detachment of metallic islands during corrosion. These results correspond to a phenomenon which has been experimentally proven, named chunk effect, and is responsible of the deviation with Faraday’s law. It is shown that effective corrosion speed is enhanced by the production of islands resulting from corrosion-erosion coupling. Secondly studies of spatially separated reactions, have shown the influence of the diffusion of acid-basic species in the solution and have permitted to carry out, an initial regime characterised by an homogenous solution, followed by diffusion limited regime, where chemical heterogeneities leading to physical heterogeneities (roughness of the front) appear. The relationship between chemical and morphological phenomena is clearly demonstrated. Finally we have demonstrated experimental deviations with Faraday’s law in the case of zinc corrosion, in sulphuric acid medium.

As a study organism, annual killifish (Austrofundulus limnaeus) provide a well suited study system for examining the effects of environmental temperature fluctuations at the cellular level. A. limnaeus persist in the harsh high desert climate of the Maracaibo Basin, Venezuela where they live in small, ephemeral freshwater pools. Temperatures in these waters can vary as much as 20 degrees C daily and reach maximums of over 40 degrees C due to the semi-arid climate. Previous cDNA microarray studies on killifish revealed the mRNA pattern for High Mobility Group Protein 1 (HMGB1) to be strongly affected by temperature perturbations. Specifically, peaks in hmgb1 transcript abundance were negatively correlated with temperature during temperature cycling, and experienced over a 10 fold difference in expression in response to the temperature cycle. Using the same temperature cycling experimental setup, this study's aim was three-fold: (1) to characterize the total amount of HMGB1 protein in adult male killifish livers, (2) to describe the subcellular localization of the HMGB1 protein in adult male killifish livers and (3) to sequence the 5' upstream region of the hmgb1 gene to identify possible stress responsive elements. We detected no significant difference in total HMGB1 protein levels as a consequence of temperature cycling. The data for subcellular localization of HGMB1 protein do not support a strong change in subcellular localization of the protein in response to temperature cycling; most of the HMGB1 protein is found in the cytoplasmic compartment in liver tissue. Although overall patterns of subcellular localization did not change significantly, we found a significant difference between nuclear HMGB1 protein levels in temperature cycled fish versus control (constant temperature) fish. This could suggest a muting of the natural translocation of HMGB1 into the nucleus observed in control fish at around 9:00 at night. Finally, the upstream region of the hgmb1 gene does reveal a number of putative stress responsive transcription factor binding sites.

Precision measurements of the Debye-Waller factor of Fe57 in Au using the wide black absorber technique have been made in the temperature range from room temperature to 830 K. The major source of error arises from Au Ly x-rays which are unresolved by the radiation detection system from the 14.4 KeV gamma ray. The K absorption edge of Br has been used to correct for the presence of x-rays. These measurements have revealed the existence of two nonequivalent lattice sites which the Co57 impurity (parent of Fe57) may occupy. One of the sites has been populated by quenching the source from temperatures greater than 1150 K and has been identified as a substitutional lattice site. From an analysis of the Mössbauer spectrum it is concluded that some of the substitutional sites may be in the vicinity of dislocations. It has been determined that the impurity-host force constant for Fe57 atoms in the substitutional site is about the same as the host-host force constant; the experimental value of the anharmonicity parameter ɛ (-2) for Fe57 in the Au is nearly the same as calculated values of ɛ (-2) for pure Au. The second site forms very slowly upon annealing the source at intermediate temperatures and has been identified as being interstitial in character. The slow rate of formation of the interstitial site indicates that diffusion is a primary mechanism in its formation. The second site must therefore be more complicated than an ordinary interstitial. It is proposed that this site is a split, or dumbbell, interstitial formed by substituting two impurity atoms for one of the Au atoms.

No description available.

No description available.

No description available.

No description available.