Infrared Spectroscopy of H2 Trapped in Metal Organic Frameworks

In this thesis we examine the hydrogen storage properties of four different materials. Because of the global climate crisis and the growing realization that petroleum resources are limited, there has been a strong push to find alternative means of energy storage. At the forefront of this push is the hydrogen economy, the idea that hydrogen gas is a bountiful, clean, alternative means of energy storage. One step towards realizing the hydrogen economy is finding a practical means of hydrogen storage. The conventional methods of hydrogen storage are in high-pressure gas cylinders or as a liquid. Both of these methods are impractical for energy storage purposes. The gas cylinders are very massive and so hold little hydrogen for their weight; and hydrogen only liquefies at -251.9° C (-421.4° F), which imposes impractical limitations on its use. The most promising alternative storage option is finding a material that traps a large quantity of hydrogen at room temperature and atmospheric pressure. At the current time, there is no known material that is a practical option for hydrogen storage. In this thesis we use infrared spectroscopy to investigate the behavior of the hydrogen inside the material and the interaction between the trapped hydrogen and the material . By refining our understanding of this interaction, we can predict what might make good storage materials. Currently, theoretical models are unable to predict energies that are correct within 25%. We successfully explain the observed behavior of the trapped hydrogen in the four materials. Our investigation also provides a wealth of data that can be used to calibrate theoretical models. These results will help guide us towards new materials that have greater potential to be viable storage alternatives

On-line economic optimization of a chemical reactor

An economic optimizing control system for a continuous flow stirred tank chemical reactor is designed, simulated, and installed on a pilot scale reactor. The control scheme utilizes a reaction and reactor model to predict on-line the economic optimum of a reactant concentration. In this manner the control system manipulates the reactant flow rate to maintain the optimum concentration during changes in reaction-reactor parameters with time. Typical parameter changes include the decay of reaction catalyst activity. The optimizing controller will function in conjunction with various operating policies including control to maintain a specified production rate --Abstract, page ii

Active Noise Control Using Modally Tuned Phase-Compensated Filters

An active noise control device or an active noise absorber (ANA) that is based on either resonant 2nd - order or 4th - order Butterworth filters is developed and demonstrated. This control method is similar to structural positive position feedback (PPF) control, with two exceptions: 1) acoustic transducers (microphone and speaker) can not be truly colocated, and 2) the acoustic actuator (loudspeaker) has significant dynamics that can affect performance and stability. Acoustic modal control approaches are typically not sought, however, there are a number of applications where controlling a few room modes is adequate. A model of a duct with speakers at each end is developed and used to demonstrate the control method, including the impact of the speaker dynamics. An all-pass filter is used to provide phase compensation and improve controller performance. Two companion experimental studies validated the simulation results. A single mode case using a resonant band-pass filter demonstrated nearly 10 dB of control in the first duct, while a multimodal case using two 4th - order Butterworth band-pass filters show both 10 dB of reduction in the fundamental mode and nearly 8.0 dB in the second

Protracted Thrusting Followed by Late Rapid Cooling of the Greater Himalayan Sequence, Annapurna Himalaya, Central Nepal: Insights from Titanite Petrochronology

Temperature-time (T-t) paths derived from coupled Zr-in-titanite thermometry and U-Pb geochronology are useful for examining middle-crustal tectonic processes. T-t data collected from the titanite-bearing calcsilicates of the upper Greater Himalayan Sequence (GHS) along the Marsyandi River, Annapurna Himalaya, illustrate a significantly different metamorphic history than previously recorded in central Nepal. Combined with traditional thermobarometry, textural relationships, and field mapping, titanite T-t data reveal a protracted history of mid-crustal tectonics. Peak Zr-in-titanite temperatures are 750-850 °C at 10-14 kbar. T-t paths are divided into two groups, which are separated by the Chame Shear Zone (CSZ). Group I (upper) rocks show cooling at rates of 1-10 °C/Ma between ca. 25 and ca. 10 Ma, while Group II (lower) rocks show heating at rates of 1-10 °C/Ma over the same time interval. Between ca. 25 and ca. 15 Ma, a thermal inversion occurs structurally upwards through Group I, but by ca. 10 Ma temperatures decrease structurally upwards. In opposition, temperatures decrease upwards in Group II rocks at all times and are as high as ~830 °C at ca. 9 Ma. While Group II rocks are interpreted as an intact, structurally-upright, section, the thermometric inversion within Group I is interpreted as thrusting of hotter rocks over colder from ca. 25 to ca. 15 Ma. The thrusting interpretation is also supported by simultaneous cooling and heating of Group I and II rocks, lithologic repetition of orthogneiss at the CSZ, and retrograde water-rich fluid flux restricted to Group I rocks. The CSZ is structurally higher than previously-identified intra-GHS thrusts in central Nepal, and thrusting duration was ~3-6 Ma longer than proposed for other identified intra-GHS thrusts in this region. Thrusting was followed by cooling at ~ 60 °C/Ma from ca. 10 Ma to Ar closure in muscovite at ca. 3.8 Ma; however, ~ 55 km to the west, cooling rates were ~ 20 °C/Ma and muscovite 40Ar/39Ar cooling ages ca. 10-15 Ma. These data suggest considerable along-strike variation in the position and duration of thrusting, as well as subsequent cooling, in the Himalaya. Formation of the Lesser Himalayan duplex in the late Miocene may have played a more important role in cooling and unroofing the GHS in the Marsyandi sector than at other locations. Additionally, exhumation from ~ 40 km depth requires erosion rates of ≥ 4.0 mm/yr, comparable to modern rates, for the past 10 Ma. Sector zoning of Zr in titanite suggests that diffusion rates are slower than determined experimentally, preserving thermometric constraints for metamorphism into the lower granulite facies

Site-specific identification and quantitation of endogenous SUMO modifications under native conditions.

Small ubiquitin-like modifier (SUMO) modification regulates numerous cellular processes. Unlike ubiquitin, detection of endogenous SUMOylated proteins is limited by the lack of naturally occurring protease sites in the C-terminal tail of SUMO proteins. Proteome-wide detection of SUMOylation sites on target proteins typically requires ectopic expression of mutant SUMOs with introduced tryptic sites. Here, we report a method for proteome-wide, site-level detection of endogenous SUMOylation that uses α-lytic protease, WaLP. WaLP digestion of SUMOylated proteins generates peptides containing SUMO-remnant diglycyl-lysine (KGG) at the site of SUMO modification. Using previously developed immuno-affinity isolation of KGG-containing peptides followed by mass spectrometry, we identified 1209 unique endogenous SUMO modification sites. We also demonstrate the impact of proteasome inhibition on ubiquitin and SUMO-modified proteomes using parallel quantitation of ubiquitylated and SUMOylated peptides. This methodological advancement enables determination of endogenous SUMOylated proteins under completely native conditions

Does the stock market make firms more productive?

Management, directly or indirectly,learns from its firm’s stock price, so a more informative stock price should make the firm more productive. We show that stock price informativeness increases firm productivity. We provide direct evidence of one channel through which stock price informativeness affects productivity; specifically, we find that CEO turnover is less sensitive to Tobin’s q when informativeness is lower. We predict and confirm that the productivity of smaller and younger firms, better governed firms, more specialized firms, and firms with more competition is more strongly related to the informativeness of their stock price. We further address endogeneity concerns with the use of brokerage closures, S&P 500 additions, and mutual fund redemptions as plausibly exogenous events

Healthy Aging Delays Scalp EEG Sensitivity to Noise in a Face Discrimination Task

We used a single-trial ERP approach to quantify age-related changes in the time-course of noise sensitivity. A total of 62 healthy adults, aged between 19 and 98, performed a non-speeded discrimination task between two faces. Stimulus information was controlled by parametrically manipulating the phase spectrum of these faces. Behavioral 75% correct thresholds increased with age. This result may be explained by lower signal-to-noise ratios in older brains. ERP from each subject were entered into a single-trial general linear regression model to identify variations in neural activity statistically associated with changes in image structure. The fit of the model, indexed by R2, was computed at multiple post-stimulus time points. The time-course of the R2 function showed significantly delayed noise sensitivity in older observers. This age effect is reliable, as demonstrated by test–retest in 24 subjects, and started about 120 ms after stimulus onset. Our analyses suggest also a qualitative change from a young to an older pattern of brain activity at around 47 ± 4 years old

A synthetic gene network for tuning protein degradation in Saccharomyces cerevisiae

Protein decay rates are regulated by degradation machinery that clears unnecessary housekeeping proteins and maintains appropriate dynamic resolution for transcriptional regulators. Turnover rates are also crucial for fluorescence reporters that must strike a balance between sufficient fluorescence for signal detection and temporal resolution for tracking dynamic responses. Here, we use components of the Escherichia coli degradation machinery to construct a Saccharomyces cerevisiae strain that allows for tunable degradation of a tagged protein. Using a microfluidic platform tailored for single-cell fluorescence measurements, we monitor protein decay rates after repression using an ssrA-tagged fluorescent reporter. We observe a half-life ranging from 91 to 22 min, depending on the level of activation of the degradation genes. Computational modeling of the underlying set of enzymatic reactions leads to GFP decay curves that are in excellent agreement with the observations, implying that degradation is governed by Michaelis–Menten-type interactions. In addition to providing a reporter with tunable dynamic resolution, our findings set the stage for explorations of the effect of protein degradation on gene regulatory and signalling pathways