Extreme Ultraviolet Reflective Grating Characterization and Simulationsfor the Aspera SmallSat Mission

The Aspera SmallSat mission is designed to detect and map the warm-hot gaseous component of the halos of nearby galaxies through long-slit spectroscopy of the ionized O VI emission line (103.2 nm) for the first time. The Aspera Rowland circle type spectrograph uses a toroidal grating coated with a multilayer film consisting of aluminum, lithium fluoride, and magnesium fluoride capping to optimize reflectivity in the extreme ultraviolet (EUV) waveband from 103 to 104nm. We discuss the grating characterization test setup at the University of Arizona (UA), which will validate the multilayer coating and grating efficiency in a UV vacuum chamber. We also simulate the reflectivity of the multilayer thin film coating using IMD IDL software to compare simulated results with measured reflectivity. Additionally, non-sequential ray trace simulations and 3D CAD modeling are used for verification of the test setup. Finally, the implications of the differences between the measured and simulated reflectivity and grating efficiencies are considered, including impact to the mission

Long-term outcomes of prophylactic placement of an endovascular balloon in the vena cava for high-risk transvenous lead extractions

Many clinicians use the strategy of prophylactically placing an endovascular balloon before transvenous lead extraction, yet there are no data regarding this practice. This study assesses long-term outcomes of prophylactic placement of an endovascular balloon in the venae cavae of patients during transvenous lead extraction. From April 1, 2016 to March 31, 2017 data were prospectively collected at 2 international cardiovascular centers on patients who had the balloon prophylactically placed in the venae cavae. Patients were monitored for a minimum of 3 months to capture any associated adverse events. Twenty-one patients had the balloon prophylactically placed in the venae cavae during lead extraction. Sixteen patients were male (76%); the mean age was 57.6 ± 18.7 years; and the mean body mass index was 26.1 ± 4.4 kg/m2. The mean lead dwell time was 11.2 ± 8.3 years, with an average of 2.2 ± 1.1 leads per case, and most indications for extraction were noninfectious (62%). Two minor complications (10%, pocket hematomas) and 1 major complication (5%, cardiac tamponade) occurred during the procedure. All cases (100%) were procedural successes, and all patients (100%) were discharged alive. On follow-up (6.8 ± 3.7 months), all patients were alive and reported no adverse events related to prophylactic balloon placement, such as pulmonary emboli or deep venous thrombi. During the study period, we observed no acute or long-term adverse outcomes associated with prophylactic placement of an endovascular balloon in the venae cavae of patients undergoing transvenous lead extraction

CFD–DEM modeling of autothermal pyrolysis of corn stover with a coupled particle- and reactor-scale framework

Autothermal operation of fast pyrolysis is an efficient process-intensification technique wherein exothermic oxidation reactions are used to overcome the heat-transfer bottleneck of conventional pyrolysis. The development of accurate, reliable modeling toolsets is imperative to generating a deeper understanding of biomass autothermal pyrolysis systems to support scale-up and industrial deployment. This modeling effort describes the development of single-particle and reactor models which incorporate detailed reaction schemes and simultaneous exothermic oxidation reactions. The particle-scale model was parameterized for corn stover feedstock with particle morphology, density, ash content, and biopolymer composition, all of which impact the emergent conversion characteristics during pyrolysis. Results were then used to parameterize a reactor-scale autothermal pyrolysis model, which was developed using a coarse-grained computational fluid dynamic–discrete element method. The simulation results compared well with experimental results, with the predicted bio-oil, light gas, and biochar yield within 3.0 wt% of the experimental yields. Further analyses were performed to test the influence of equivalence ratio, biomass injection position, and particle size distribution on autothermal pyrolysis. The analysis of the physio-chemical properties of the fluid and solid phase inside the reactor and at the reactor outlet help reveal important process interactions of autothermal pyrolysis.This article is published as Oyedeji, Oluwafemi A., M. Brennan Pecha, Charles EA Finney, Chad A. Peterson, Ryan G. Smith, Zachary G. Mills, Xi Gao et al. "CFD–DEM modeling of autothermal pyrolysis of corn stover with a coupled particle-and reactor-scale framework." Chemical Engineering Journal 446 (2022): 136920. DOI: 10.1016/j.cej.2022.136920. Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted