Despite the known benefits of performing aerobic and resistance exercise independently, the metabolic effects of performing aerobic and resistance exercise in succession, remain unclear. Several studies suggest that the alteration of exercise sequence may influence carbohydrate and lipid oxidation and energy expenditure during exercise and in recovery. High intensity resistance exercise performed prior to a bout of aerobic exercise has been shown to augment fat oxidation during the subsequent bout of aerobic exercise. Changes in hormone and metabolite concentrations from prior resistance exercise could potentially influence substrate selection and energy expenditure in a subsequent bout of aerobic exercise. However, an exercise session whereby aerobic exercise is followed by a bout of resistance exercise has yet to be evaluated to determine the metabolic effects (specifically, the differences in substrate selection for energy provision) when exercise sequence is altered. It was hypothesized that when resistance exercise was performed prior to a bout of aerobic exercise, sympathetic nervous system activity would be elevated, leading to an increase in non-esterified fatty acid (NEFA) and glycerol concentrations and resultant increase in lipid oxidation during the aerobic portion of the exercise compared to the opposite sequence. It was also hypothesized that during recovery there would be an increased reliance on fat oxidation for energy provision with a resistance-aerobic exercise sequence compared to an aerobic-resistance exercise sequence. Additionally, the differences in metabolite concentrations and respiratory parameters between two identical bouts of aerobic exercise performed on separate days (~1 week apart) were measured and it was hypothesized that day-to-day variability would be non-significant (p>0.05). Plasma glucose, lactate, NEFA, glycerol, insulin, C-peptide, glucagon, epinephrine and norepinephrine concentrations in addition to oxygen consumption (VO2) and respiratory exchange ratio (RER) were measured in nine healthy, recreationally active males that participated in 3 different, randomized exercise trials (Trial A: aerobic exercise; Trial AR: aerobic exercise followed by a bout of resistance exercise; Trial RA: resistance exercise followed by an aerobic exercise bout). The aerobic exercise bout was performed at 60% VO2 max for 30 min while the resistance exercise bout consisted of 5 exercises (overhead squat, chest press, triceps extension, shoulder press, and dead-lift) performed for 3 sets of 8 repetitions at 70% 1-RM. Contrary to the primary hypothesis, NEFA concentrations and lipid oxidation rates were similar for the aerobic exercise bout of both the AR and RA trials. During recovery, lipid oxidation was elevated immediately post-exercise in the RA trial compared to the AR trial, however there were no differences between trials by 15 min post-exercise. Furthermore, only epinephrine, and not norepinephrine, concentrations were significantly higher after aerobic exercise in the RA trial compared to the AR trial. VO2 and energy expenditure values were similar for the duration of the 30 min recovery. These results suggest that while exercise sequence may influence carbohydrate and lipid oxidation immediately post exercise, substrate selection and utilization are similar during aerobic exercise bouts irrespective of the sequence in which aerobic and resistance exercise are performed. Thus, when resistance exercise is performed prior to aerobic exercise, compared to the opposite sequence, overall energy provision is not altered at the volume and intensity of exercise performed in this study.

In this thesis, we successfully fabricated patterned semiconductor substrates, edge-emitting lasers with deeply etched distributed Bragg reflectors (DBRs), two-dimensional photonic crystals (2DPCs) and two-dimensional photonic crystal microcavities (2DPC microcavities) by electron-beam lithography and inductively coupled plasma-reactive ion etching (ICP-RIE). We have obtained a minimum writing linewidth of 50nm and a maximum writing range of 500¡Ñ500µm2 in our electron-beam lithography system. Pitch arrays of 100nm pitch-diameter and 100nm separation have been formed on 100¡Ñ100µm2 semiconductor substrates. The etching depth of patterned Si substrates and patterned GaAs substrates are 50nm and 20nm, respectively. In the design of edge-emitting lasers with deeply etched DBRs, two and three pairs of DBRs were formed on the edge of laser cavity, respectively. To obtain high reflectance at wavelength (£f) = 960nm, 209nm mirror width and 240nm or 720nm air gap were fabricated. In the design of 2DPCs, a triangular array of air columns was adopted. The lattice constant (A) and column radius (R) are 742nm and 327nm, respectively. It has a band gap for TE modes corresponding to wavelength range in 936.45nm~968.85nm. We placed single defect in the 2DPCs to form 2DPC microcavities. In addition, we simulated the photonic band structure of a seven-defect 2DPC microcavity with A = 224nm and R = 56nm. We obtained a monopole defect mode at £f = 959.86nm. To measure 2DPCs and 2DPC microcavities, we have set up a micro-photoluminescence (Micro-PL) spectrum measurement system. We observed the Micro-PL intensity of the 2DPC microcavity is 4.5 times larger than 2DPCs at £f = 960nm in the same pumping power. The 2DPC microcavities show a lasing performance under optical pumping. The threshold power of 2DPC microcavities is 5.13mW~6.81mW at room temperature and decreases to 1.4mW~3.13mW at 15¢J.

Despite the known benefits of performing aerobic and resistance exercise independently, the metabolic effects of performing aerobic and resistance exercise in succession, remain unclear. Several studies suggest that the alteration of exercise sequence may influence carbohydrate and lipid oxidation and energy expenditure during exercise and in recovery. High intensity resistance exercise performed prior to a bout of aerobic exercise has been shown to augment fat oxidation during the subsequent bout of aerobic exercise. Changes in hormone and metabolite concentrations from prior resistance exercise could potentially influence substrate selection and energy expenditure in a subsequent bout of aerobic exercise. However, an exercise session whereby aerobic exercise is followed by a bout of resistance exercise has yet to be evaluated to determine the metabolic effects (specifically, the differences in substrate selection for energy provision) when exercise sequence is altered. It was hypothesized that when resistance exercise was performed prior to a bout of aerobic exercise, sympathetic nervous system activity would be elevated, leading to an increase in non-esterified fatty acid (NEFA) and glycerol concentrations and resultant increase in lipid oxidation during the aerobic portion of the exercise compared to the opposite sequence. It was also hypothesized that during recovery there would be an increased reliance on fat oxidation for energy provision with a resistance-aerobic exercise sequence compared to an aerobic-resistance exercise sequence. Additionally, the differences in metabolite concentrations and respiratory parameters between two identical bouts of aerobic exercise performed on separate days (~1 week apart) were measured and it was hypothesized that day-to-day variability would be non-significant (p>0.05). Plasma glucose, lactate, NEFA, glycerol, insulin, C-peptide, glucagon, epinephrine and norepinephrine concentrations in addition to oxygen consumption (VO2) and respiratory exchange ratio (RER) were measured in nine healthy, recreationally active males that participated in 3 different, randomized exercise trials (Trial A: aerobic exercise; Trial AR: aerobic exercise followed by a bout of resistance exercise; Trial RA: resistance exercise followed by an aerobic exercise bout). The aerobic exercise bout was performed at 60% VO2 max for 30 min while the resistance exercise bout consisted of 5 exercises (overhead squat, chest press, triceps extension, shoulder press, and dead-lift) performed for 3 sets of 8 repetitions at 70% 1-RM. Contrary to the primary hypothesis, NEFA concentrations and lipid oxidation rates were similar for the aerobic exercise bout of both the AR and RA trials. During recovery, lipid oxidation was elevated immediately post-exercise in the RA trial compared to the AR trial, however there were no differences between trials by 15 min post-exercise. Furthermore, only epinephrine, and not norepinephrine, concentrations were significantly higher after aerobic exercise in the RA trial compared to the AR trial. VO2 and energy expenditure values were similar for the duration of the 30 min recovery. These results suggest that while exercise sequence may influence carbohydrate and lipid oxidation immediately post exercise, substrate selection and utilization are similar during aerobic exercise bouts irrespective of the sequence in which aerobic and resistance exercise are performed. Thus, when resistance exercise is performed prior to aerobic exercise, compared to the opposite sequence, overall energy provision is not altered at the volume and intensity of exercise performed in this study.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 60-62). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 43-45). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 69-72). Also available on the World Wide Web.

The effect of substrate surface topology on the interaction of living cells with inanimate substrates is a well-established phenomenon. When cells are placed on biomaterials, they outgrow protrusions called filopodia that sense surface features in their immediate surroundings and initiate the formation of stable cell adhesion complexes closer to the cell body. Adhesion proteins permit filopodia to constantly explore the surrounding microenvironment. A better understanding of the relationship of filopodia with surface features is highly relevant for exploiting custom-made surfaces to guide cell activity. In this work, mathematical modeling and simulation were used to describe different phenomena related to the interaction of a filopodium with its microenvironment, with the aim of reproducing experimentally observed phenomena associated to filopodia growth and interactions with substrates. The Kelvin Voigt model was used for the viscoelastic response of filopodia. Result predict filopodia protrusion under test conditions and helps improving our understanding on the effect of substrate topology on the biomechanical response of filopodial extensions.

Nitrogen (N) is a chemical constituent for almost all biological molecules including proteins, DNA, RNA, lipids and is therefore vital for life. The ultimate source of nitrogen is the atmospheric dinitrogen (N2) but that only becomes bioavailable through a process of nitrogen fixation, the process that converts N2 to ammonia (NH3). The industrial Haber-Bosch process and biological nitrogen fixation account for the majority of nitrogen fixed every year. However, due to its high temperature, pressure and fossil fuel requirements, Haber-Bosch is an expensive process. Every year, approximately 3% of the global energy demand is used to manufacture ammonia through Haber-Bosch process. On the other hand, biological systems produce ammonia by reducing dinitrogen at ambient temperature and pressure using an anaerobic enzyme called nitrogenase. Research in understanding the mechanism of nitrogenase could eventually allow researchers to mimic the enzyme and fix nitrogen efficiently at standard temperature and pressure. In this research nitrogenase of Azotobacter vinelandii was studied to understand the mechanism of delivery of electrons/protons to the active site and how these accumulated reducing equivalents are used for substrates reduction. Through a series of studies, it has been demonstrated that the electrons and protons are added to the active site in a concerted manner which are then stored as bridging hydrides. The accumulated hydrides are used in four different mechanisms, namely reductive elimination, hydride protonolysis, migratory insertion and proton coupled electron transfer, to catalyze the reduction of varieties of unsaturated molecules. This fundamental understanding of molecular detail of nitrogenase catalysis could eventually help in development of more efficient, robust and selective catalysts.

The availability of substrates is one of the most important environmental constraints on the diversity and functioning of microorganisms. Substrate quantity and quality as well as the metabolic features of heterotrophic microorganisms determine the efficiency, speed and type of transformation that can occur in nature. As such their interplay with the environment regulates how much carbon and energy is incorporated by bacteria and subsequently reaches higher trophic levels. In lakes the bulk substrate that is available for bacteria is composed of a complex mixture of compounds, varying in lability and distribution in the environment. This thesis addresses the coupling of organic substrates, their metabolic use and the composition and ecology of the microbial community. Controlled laboratory experiments with mixed bacterial communities in either batch cultures or chemostats were designed to shed further light on bacterial use of labile and quantitatively significant carbon compounds. I show that different amino acid substrates only exert a minor influence on bacterioplankton community composition and growth. Hence the ability to use a wide range of such abundantly produced protein monomers seems to be widespread among freshwater bacteria. In contrast, when acetate was provided as the only carbon substrate, in either pulsed or continuous amendments, this very different substrate input mode had a strong effect on bacterial community composition. Biomass yield, for example, was twice as high when acetate was given in the form of pulses rather than provided continuously. In another set of experiments, I show that the oxidation of the globally significant greenhouse gas methane is a process that can potentially take place at the water-ice interface of seasonally ice-covered lakes and was not constrained by temperature as suggested in previous studies. This work also suggests that methane oxidation in ice-covered lakes can be constrained by competition for nutrients between specialized methanotrophs and heterotrophic bacteria. Combined these studies suggest that some labile substrates cause minor selection on bacterial community structure and functioning. This probably reflects the competitive advantage of using a broad range of low molecular weight substrates. However, as in the case of methanotrophs there is specialization for a specific low molecular weight substrate such as methane. In which case, competition with other community members i.e. for nutrients can constrain methane oxidation. In both cases it might however not depend just on the availability of substrate, but also on how substrates are distributed in time and space.

No description available.