The design and development of hydrogen isotope extraction technologies for a limit-style liquid lithium loop

As lithium has grown in popularity as a plasma-facing material, efforts have been placed on examining its viability as a first wall candidate. Lithium has proven over numerous studies to improve core confinement, while allowing access to operational regimes previously unattainable while using solid, high-Z divertor and limiter modules. These benefits are due to the fuel retention capabilities of lithium, which allow it to be an almost ideally absorbing boundary, which is both beneficial and problematic. While lithium exhibits a number of other advantages and disadvantages as a plasma-facing material, none is more important than the tritium retention problem. As such, extraction technologies must be constructed and verified within the scope of larger scale lithium loop systems that separate lithium impurities, recover deuterium and tritium, and recycle clean liquid lithium back to the plasma-material interface. Laboratory-scale and pilot-scale studies have been conducted at the Center for Plasma-Material Interactions at the University of Illinois to investigate a number of phenomena that influence the recovery of entrained tritium from lithium. While the ultimate goal is to develop a fully-functional liquid lithium loop for the Lithium Metal Infused Trenches plasma-facing component, complete with efficient hydrogen reclamation technologies, there exists a lack in understanding within the community of the thermochemical fundamentals that are envisioned to drive tritium reclamation. Of specific interest are the evolution fluxes of hydrogen isotopes from solutions of various concentrations of hydrogen in lithium, and the associated temperatures. The knowledge of how the isotopic fraction affects recovery is pivotal to determining the appropriate thermal treatment technique. The laboratory-scale experiments in this report aimed at filling in the knowledge gaps in the literature with regards to the thermochemistry of the hydrogen-lithium system. In all cases, hydrogen was used as an isotopic surrogate for deuterium and tritium. Success was based on an individual samples ability to evolve molecular hydrogen at rates that would match or exceed in-vessel wall losses, determined from a simulated Lithium-Walled International Thermonuclear Experimental Reactor scenario. The hydrogen degassing of pure lithium hydride was observed to exceed fuel loss by a factor of two or greater, at temperatures near the melting point for hydride. Samples of both solid and liquid lithium were subjected to different hydrogen environments under a variety of exposure conditions. During plasma exposures, evidence of saturation, where hydride layers are formed at or near the sample surface and inhibit hydrogen absorption, was witnessed for solid lithium samples. Liquid samples exhibited this behavior to a lesser degree; however, mass diffusion was able to transport the insulating species away from the surface and absorption was able to continue, albeit to a lesser extent than was initially detected. The sub-surface chemistry was found to still be limited by the thermodynamic solubility thresholds in a plasma environment, meaning enhanced hydrogen dissolution was not witnessed at ion energies relevant to these experiments. The presence of a plasma, however, did appear to enhance absorption rates above and beyond what was capable with hydrogen gas alone. During these tests, hydrogen evolution rates from the dissolved phase never approached the point of being able to balance losses at the plasma-material interface, being always less by a factor of two or more. It was therefore determined that supplementary methods were required to enhance thermal-based recovery in solutions with hydrogen molar ratios less than the solubility limits. This work culminated in the design, development, construction, and proof-of-concept testing of a distillation column. Envisioned to be an integrated treatment method in a fully functional lithium loop, the column was developed based on the need to recover tritium and recycle fresh lithium back into the reactor. The novelty in this design was in its use of induction heating drive and condensation stages. Proof-of-concept tests were performed in the fully constructed prototype with solutions of lithium and lithium hydride at various molar ratios. The system was observed to operate as intended during these initial runs, but requires further testing; however, the column marks the first system constructed for the sole purpose of recovering tritium from a lithium-walled reactor. Such a system will prove most effective if upstream separation and purification techniques are present to divert the lithium deuteride and lithium tritide-rich streams to the column for thermal decomposition and degassing. In the case where upstream purification modules are absent from the lithium loop, the column alone will be hard pressed to achieve recovery rates in far-from-saturated solutions that balance wall losses. A technique to supplement the induction heating drive was therefore proposed. Ultrasonic degassing of liquid metals is an industry-tested technique used to rid melts of dissolved gases by taking advantage of acoustically-induced cavitation. This process was theoretically applied to the hydrogen-lithium system, displaying evidence that degassing is most effective in the presence of heat, ultrasonic waves, and vacuum. This work laid the theoretical groundwork for future application. The results presented in this report show that using the appropriate combination of treatment methods, hydrogen, and by extension deuterium and tritum, can be recovered from lithium at rates that balance in-vessel wall loss. Future work will be needed to then integrate these methods into a fully functional liquid lithium loop

Characterization of ion properties in a linear pulsed plasma-material interaction test stand

In the edge and divertor regions of the magnetically confined plasma, tokamaks experience off-normal events in which high intensities of heat flux incident on wall component surfaces result in intolerable levels of damage. Proposed solid divertors will not be able to withstand these fluxes, especially in larger toroidal machines such as ITER and DEMO. In addition to this detrimental effect on solid wall materials, demonstrations have shown that the erosion of these materials can cause impurity generation and transport within the bulk plasma, leading to high radiative losses. To avoid these and other major issues, liquid metal divertor and wall schemes have been proposed and studies have been done to understand their effect on bulk tokamak plasmas. To simulate extreme events in the tokamak boundary and provide a test stand for liquid-metal plasma-facing components, a pulsed plasma source utilizing a theta pinch in conjunction with a coaxial plasma accelerator has been developed[1-3]. The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) device will provide fusion-relevant plasma flux incident on structures with flowing liquid metal surfaces. In order to accurately quantify the ability of TELS to provide a simulated disruption or edge localized mode (ELM) plasma, a suite of diagnostics was used to measure a variety of plasma parameters. The objective of this thesis was to develop an electrostatic analyzer to measure the ion information in TELS and use the results to understand particle energy distribution and loss as a function of distance from the plasma source. It has been previously observed that TELS plasmas can bombard a target with an electron density of 3 x 1021 m-3, an electron temperature of 20 to 30 eV, and a peak energy flux of 0.08 MJ/m2 over the pulse length of 100 to 200 µs[2]. To validate that the experimentally observed heat flux delivered to a target corresponds to the isotropic magnetohydrodynamic (MHD) predictions based on electron and ion temperatures, it became necessary to evaluate the ion temperature and subsequent energy distribution. In addition to these theoretical comparisons, the ion temperature and transport of ions down the length of the chamber is important in order to fully characterize a system that preferentially heats and accelerates ions as a function of the energy coupling in the theta pinch. Two major conditions were imposed to observe how ions behave as a function of the effect of the compression with the theta pinch. First, the analyzer system comprised of an analyzer open to the plasma and an analyzer closed to the plasma was inserted into the target chamber, at a distance of 16 inches (40.6 cm) downstream of the theta pinch. The closed analyzer was used as an experimental control, so that the effects of electromagnetic and circuit noise were eliminated from the open analyzer signal. The ion current showed two prominent features that followed in suit with the way the PiP discharges, and the time-averaged temperatures were taken with respect to the duration of these features during the pulse. Without guiding magnetic fields used to prevent ion diffusive losses, the measured ion signal showed an ion temperature of 22.83 ± 7.43 eV for the first peak and 17.59 ± 11.53 eV for the second peak. This measurement was used as a basis against which to compare ion temperatures subject to different pulse conditions. Secondly, the analyzer system measured the ion information from the use of only the coaxial plasma accelerator as a comparison by which the theta pinch can be proven effective or not. Without the use of guiding fields, the measured signal showed an ion temperature of 10.40 ± 6.62 eV for the first peak and 7.70 ± 3.57 eV for the second peak. The effects of these results from a plasma transport and a plasma-material interaction basis will be discussed

N-Terminal Pro–B-Type Natriuretic Peptide in the Emergency Department: The ICON-RELOADED Study

Background Contemporary reconsideration of diagnostic N-terminal pro–B-type natriuretic peptide (NT-proBNP) cutoffs for diagnosis of heart failure (HF) is needed. Objectives This study sought to evaluate the diagnostic performance of NT-proBNP for acute HF in patients with dyspnea in the emergency department (ED) setting. Methods Dyspneic patients presenting to 19 EDs in North America were enrolled and had blood drawn for subsequent NT-proBNP measurement. Primary endpoints were positive predictive values of age-stratified cutoffs (450, 900, and 1,800 pg/ml) for diagnosis of acute HF and negative predictive value of the rule-out cutoff to exclude acute HF. Secondary endpoints included sensitivity, specificity, and positive (+) and negative (−) likelihood ratios (LRs) for acute HF. Results Of 1,461 subjects, 277 (19%) were adjudicated as having acute HF. The area under the receiver-operating characteristic curve for diagnosis of acute HF was 0.91 (95% confidence interval [CI]: 0.90 to 0.93; p < 0.001). Sensitivity for age stratified cutoffs of 450, 900, and 1,800 pg/ml was 85.7%, 79.3%, and 75.9%, respectively; specificity was 93.9%, 84.0%, and 75.0%, respectively. Positive predictive values were 53.6%, 58.4%, and 62.0%, respectively. Overall LR+ across age-dependent cutoffs was 5.99 (95% CI: 5.05 to 6.93); individual LR+ for age-dependent cutoffs was 14.08, 4.95, and 3.03, respectively. The sensitivity and negative predictive value for the rule-out cutoff of 300 pg/ml were 93.9% and 98.0%, respectively; LR− was 0.09 (95% CI: 0.05 to 0.13). Conclusions In acutely dyspneic patients seen in the ED setting, age-stratified NT-proBNP cutpoints may aid in the diagnosis of acute HF. An NT-proBNP <300 pg/ml strongly excludes the presence of acute HF

Working hard on the outside: a multimodal critical discourse analysis of The Biggest Loser Australia

The Biggest Loser (TBL) is a reality television weight-loss programme that positions itself as a response to the so-called “obesity crisis”. Research on TBL has thus far focussed on audience responses and its effect on viewers’ beliefs about weight loss. This article focuses instead on how meaning is constructed in TBL. We conducted a multimodal critical discourse analysis of a key episode of TBL (the 2012 Australian season finale) to examine how the textual, visual and auditory elements combine to construct meanings beyond the ostensible health messages. Although the overt message is that all contestants have worked hard, turned their lives around and been “successful”, examination of editing choices, lighting and colour, clothing and time spent on contestants allows us to see that the programme constructs varying degrees of success between contestants and provides accounts for these differences in outcomes. In this way the programme is able to present itself as a putative celebration of all contestants while prescribing narrow limits around what constitutes success. TBL reinforces an ideology in which “success” is a direct result of “the work” of weight loss (both physical and emotional), which can apparently be read straightforwardly off the body. TBL’s “celebration” of weight loss thus reproduces and strengthens the widespread view of fat bodies as physical manifestations of individual (ir)responsibility and psychological dysfunction, and contributes to the ongoing stigmatisation of obesity

Reduced Snow Cover Alters Root-microbe Interactions and Decreases Nitrification Rates in a Northern Hardwood Forest

Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze-thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow will affect root-microbe interactions remains largely unknown. The objective of this study was to distinguish and attribute direct (e.g., winter snow-and/ or soil frost-mediated) vs. indirect (e.g., root-mediated) effects of winter climate change on microbial biomass, the potential activity of microbial exoenzymes, and net N mineralization and nitrification rates. Soil cores were incubated in situ in nylon mesh that either allowed roots to grow into the soil core (2 mm pore size) or excluded root ingrowth (50 μm pore size) for up to 29 months along a natural winter climate gradient at Hubbard Brook Experimental Forest, NH (USA). Microbial biomass did not differ among ingrowth or exclusion cores. Across sampling dates, the potential activities of cellobiohydrolase, phenol oxidase, and peroxidase, and net N mineralization rates were more strongly related to soil volumetric water content (P \u3c 0.05; R2 = 0.25–0.46) than to root biomass, snow or soil frost, or winter soil temperature (R2 \u3c 0.10). Root ingrowth was positively related to soil frost (P \u3c 0.01; R2 = 0.28), suggesting that trees compensate for overwinter root mortality caused by soil freezing by re-allocating resources towards root production. At the sites with the deepest snow cover, root ingrowth reduced nitrification rates by 30% (P \u3c 0.01), showing that tree roots exert significant influence over nitrification, which declines with reduced snow cover. If soil freezing intensifies over time, then greater compensatory root growth may reduce nitrification rates directly via plant-microbe N competition and indirectly through a negative feedback on soil moisture, resulting in lower N availability to trees in northern hardwood forests

Rationale and Design of the ICON-RELOADED Study: International Collaborative of Nterminal pro-B-type Natriuretic Peptide Re-evaluation of Acute Diagnostic Cut-Offs in the Emergency Department

Objectives The objectives were to reassess use of amino-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations for diagnosis and prognosis of acute heart failure (HF) in patients with acute dyspnea. Background NT-proBNP facilitates diagnosis, prognosis, and treatment in patients with suspected or proven acute HF. As demographics of such patients are changing, previous diagnostic NT-proBNP thresholds may need updating. Additionally, value of in-hospital NT-proBNP prognostic monitoring for HF is less understood. Methods In a prospective, multicenter study in the United States and Canada, patients presenting to emergency departments with acute dyspnea were enrolled, with demographic, medication, imaging, and clinical course information collected. NT-proBNP analysis will be performed using the Roche Diagnostics Elecsys proBNPII immunoassay in blood samples obtained at baseline and at discharge (if hospitalized). Primary end points include positive predictive value of previously established age-stratified NT-proBNP thresholds for the adjudicated diagnosis of acute HF and its negative predictive value to exclude acute HF. Secondary end points include sensitivity, specificity, and positive and negative likelihood ratios for acute HF and, among those with HF, the prognostic value of baseline and predischarge NT-proBNP for adjudicated clinical end points (including all-cause death and hospitalization) at 30 and 180 days. Results A total of 1,461 dyspneic subjects have been enrolled and are eligible for analysis. Follow-up for clinical outcome is ongoing. Conclusions The International Collaborative of N-terminal pro–B-type Natriuretic Peptide Re-evaluation of Acute Diagnostic Cut-Offs in the Emergency Department study offers a contemporary opportunity to understand best diagnostic cutoff points for NT-proBNP in acute HF and validate in-hospital monitoring of HF using NT-proBNP

The sputum transcriptome better predicts COPD exacerbations after the withdrawal of inhaled corticosteroids than sputum eosinophils

INTRODUCTION: Continuing inhaled corticosteroid (ICS) use does not benefit all patients with COPD, yet it is difficult to determine which patients may safely sustain ICS withdrawal. Although eosinophil levels can facilitate this decision, better biomarkers could improve personalised treatment decisions. METHODS: We performed transcriptional profiling of sputum to explore the molecular biology and compared the predictive value of an unbiased gene signature versus sputum eosinophils for exacerbations after ICS withdrawal in COPD patients. RNA-sequencing data of induced sputum samples from 43 COPD patients were associated with the time to exacerbation after ICS withdrawal. Expression profiles of differentially expressed genes were summarised to create gene signatures. In addition, we built a Bayesian network model to determine coregulatory networks related to the onset of COPD exacerbations after ICS withdrawal. RESULTS: In multivariate analyses, we identified a gene signature (LGALS12, ALOX15, CLC, IL1RL1, CD24, EMR4P) associated with the time to first exacerbation after ICS withdrawal. The addition of this gene signature to a multiple Cox regression model explained more variance of time to exacerbations compared to a model using sputum eosinophils. The gene signature correlated with sputum eosinophil as well as macrophage cell counts. The Bayesian network model identified three coregulatory gene networks as well as sex to be related to an early versus late/nonexacerbation phenotype. CONCLUSION: We identified a sputum gene expression signature that exhibited a higher predictive value for predicting COPD exacerbations after ICS withdrawal than sputum eosinophilia. Future studies should investigate the utility of this signature, which might enhance personalised ICS treatment in COPD patients

Roots Mediate the Effects of Snowpack Decline on Soil Bacteria, Fungi, and Nitrogen Cycling in a Northern Hardwood Forest

Rising winter air temperature will reduce snow depth and duration over the next century in northern hardwood forests. Reductions in snow depth may affect soil bacteria and fungi directly, but also affect soil microbes indirectly through effects of snowpack loss on plant roots. We incubated root exclusion and root ingrowth cores across a winter climate-elevation gradient in a northern hardwood forest for 29 months to identify direct (i.e., winter snow-mediated) and indirect (i.e., root-mediated) effects of winter snowpack decline on soil bacterial and fungal communities, as well as on potential nitrification and net N mineralization rates. Both winter snowpack decline and root exclusion increased bacterial richness and phylogenetic diversity. Variation in bacterial community composition was best explained by differences in winter snow depth or soil frost across elevation. Root ingrowth had a positive effect on the relative abundance of several bacterial taxonomic orders (e.g., Acidobacterales and Actinomycetales). Nominally saprotrophic (e.g., Saccharomycetales and Mucorales) or mycorrhizal (e.g., Helotiales, Russalales, Thelephorales) fungal taxonomic orders were also affected by both root ingrowth and snow depth variation. However, when grouped together, the relative abundance of saprotrophic fungi, arbuscular mycorrhizal fungi, and ectomycorrhizal fungi were not affected by root ingrowth or snow depth, suggesting that traits in addition to trophic mode will mediate fungal community responses to snowpack decline in northern hardwood forests. Potential soil nitrification rates were positively related to ammonia-oxidizing bacteria and archaea abundance (e.g., Nitrospirales, Nitrosomondales, Nitrosphaerales). Rates of N mineralization were positively and negatively correlated with ectomycorrhizal and saprotrophic fungi, respectively, and these relationships were mediated by root exclusion. The results from this study suggest that a declining winter snowpack and its effect on plant roots each have direct effects on the diversity and abundance of soil bacteria and fungal communities that interact to determine rates of soil N cycling in northern hardwood forests