A Model Compound Study in Syngas Tar Reforming

Biomass or coal gasification are promising processes for renewable energy. However, a major operating problem in gasification is what to do with syngas byproducts such as H2S and tars (heavy hydrocarbons) that cause catalyst deactivation downstream. Studies have shown that rare earth oxides (REOs) doped with transition metals are promising catalysts for tar reforming in the presence of sulfur.(R. Li, Roy, Bridges, & Dooley, 2014) In Chapter 1, propane is studied as a model compound for tar reforming with transition metal-doped (e.g., Mn, Fe) REOs. These are compared to a typical commercial Ni/Al2O3 catalyst. The results showed that REO/TM catalysts have higher reforming activity over the temperature range 920-1000 K, with no significant deactivation in non-sulfur containing feeds. In particular, Mn/Ce4, Mn1.1/Ce3/La and La/Ce3 (the numbers are elemental ratios) showed good reforming activity with relatively low carbon, CO2 and CH4 yields. Mn/Ce4 showed some, but not complete, deactivation when tested with an H2S-containing feed. All used catalysts were subjected to TPO analysis and H2 chemisorption. No correlation could be found between either reforming activity or carbon yield (as calculated from the mass balances), or the TPO or dispersion (chemisorption) results, although the dispersions did show that the transition metals remained doped in the REOs. Kinetics calculations showed that most of the catalysts have near zero-order kinetics with respect to water. In Chapter 2, educational modules related to biomass unit operations are presented, as part of the Energy Sustainability Remote Laboratory (ESRL) project. The modules relate to a biological pH-swing crystallization and a sugar-milling process. Brief introductions to the fundamental theories of both unit operations are provided to aid students’ understanding of them. Laboratory assignments and exercises are designed to focus on enhancing students’ experiences in typical operating problems, such as analyzing and finding discrepancies in experimental data, building mass balances around units, and analyzing relevant probability distributions related to the data. Students can utilize mathematical software such as Excel’s Solver and Matlab to complete certain assignments. Written solutions, Excel spreadsheets and Matlab codes for laboratory assignments and exercises are provided in Appendix C

How to establish the outer limits of reperfusion therapy

Reperfusion therapy with intravenous alteplase and endovascular therapy are effective treatments for selected patients with acute ischemic stroke. Guidelines for treatment are based upon randomized trials demonstrating substantial treatment effects for highly selected patients based on time from stroke onset and imaging features. However, patients beyond the current established guidelines might benefit with lesser but still clinically significant treatment effects. The STAIR (Stroke Treatment Academic Industry Roundtable) XI meeting convened a workgroup to consider the “outer limits” of reperfusion therapy by defining the current boundaries, and exploring optimal parameters and methodology for determining the outer limits. In addition to statistical significance, the minimum clinically important difference should be considered in exploring the limits of reperfusion therapy. Societal factors and quality of life considerations should be incorporated into assessment of treatment efficacy. The threshold for perception of benefit in the medical community may differ from that necessary for the Food and Drug Administration approval. Data from alternative sources such as platform trials, registries and large pragmatic trials should supplement randomized controlled trials to improve generalizability to routine clinical practice. Further interactions between industry and academic centers should be encouraged

Acute stroke imaging research roadmap IV : imaging selection and outcomes in acute stroke clinical trials and practice

Background and Purpose: The Stroke Treatment Academic Industry Roundtable (STAIR) sponsored an imaging session and workshop during the Stroke Treatment Academic Industry Roundtable XI via webinar on October 1 to 2, 2020, to develop consensus recommendations, particularly regarding optimal imaging at primary stroke centers. Methods: This forum brought together stroke neurologists, neuroradiologists, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke, industry representatives, and members of the US Food and Drug Administration to discuss imaging priorities in the light of developments in reperfusion therapies, particularly in an extended time window, and reinvigorated interest in brain cytoprotection trials. Results: The imaging session summarized and compared the imaging components of recent acute stroke trials and debated the optimal imaging strategy at primary stroke centers. The imaging workshop developed consensus recommendations for optimizing the acquisition, analysis, and interpretation of computed tomography and magnetic resonance acute stroke imaging, and also recommendations on imaging strategies for primary stroke centers. Conclusions: Recent positive acute stroke clinical trials have extended the treatment window for reperfusion therapies using imaging selection. Achieving rapid and high-quality stroke imaging is therefore critical at both primary and comprehensive stroke centers. Recommendations for enhancing stroke imaging research are provided

Rare Earth/Transition Metal Oxides for Syngas Tar Reforming: A Model Compound Study

A major problem in biomass or coal gasification is removal of syngas byproducts such as H₂S, NH₃, and tars (heavy hydrocarbons) that cause catalyst deactivation and clogging problems downstream. Rare earth oxides (REOs) doped with transition metals (TMs) are promising catalysts for tar reforming. With propane as a model compound, we compared such catalysts to a typical supported Ni catalyst, and also to recent density functional theory (DFT) results modeling these systems. The REO/TM catalysts are active over the range 920–1000 K, with no significant deactivation in non-sulfur containing feeds. In particular, a Mn/CeO₂ catalyst showed good reforming activity with low carbon, CO₂, and CH₄ yields. This catalyst also maintained some activity in the presence of 40 ppm H₂S. Kinetics calculations showed that most such catalysts have near zero order kinetics with respect to water, making them usable with a variety of gasifier effluents. Characterization of used catalysts by multiple techniques suggests that the metal-doped REOs do not undergo much (if any) phase separation in extended use under tar reforming conditions, with Mn- and La-doped CeO₂ being especially stable

A Molecular Dynamics Study of Ca(2+)-Calmodulin: Evidence of Interdomain Coupling and Structural Collapse on the Nanosecond Timescale

A 20-ns molecular dynamics simulation of Ca(2+)-calmodulin (CaM) in explicit solvent is described. Within 5 ns, the extended crystal structure adopts a compact shape similar in dimension to complexes of CaM and target peptides but with a substantially different orientation between the N- and C-terminal domains. Significant interactions are observed between the terminal domains in this compact state, which are mediated through the same regions of CaM that bind to target peptides derived from protein kinases and most other target proteins. The process of compaction is driven by the loss of helical structure in two separate regions between residues 75–79 and 82–86, the latter being driven by unfavorable electrostatic interactions between acidic residues. In the first 5 ns of the simulation, a substantial number of contacts are observed between the first helix of the N-terminal domain and residues 74–77 of the central linker. These contacts are correlated with the closing of the second EF-hand, indicating a mechanism by which they can lower calcium affinity in the N-terminal domain