Quantifying Differences in the Impact of Variable Chemistry on Equilibrium Uranium(VI) Adsorption Properties of Aquifer Sediments

Uranium adsorption − desorption on sediment samples collected from the Hanford 300-Area, Richland, WA varied extensively over a range of field-relevant chemical conditions, complicating assessment of possible differences in equilibrium adsorption properties. Adsorption equilibrium was achieved in 500−1000 h although dissolved uranium concentrations increased over thousands of hours owing to changes in aqueous chemical composition driven by sediment-water reactions. A nonelectrostatic surface complexation reaction, \u3eSOH + UO22+ + 2CO32- = \u3eSOUO2(CO3HCO3)2- , provided the best fit to experimental data for each sediment sample resulting in a range of conditional equilibrium constants (logKc) from 21.49 to 21.76. Potential differences in uranium adsorption properties could be assessed in plots based on the generalized massaction expressions yielding linear trends displaced vertically by differences in logKc values. Using this approach, logKc values for seven sediment samples were not significantly different. However, a significant difference in adsorption properties between one sediment sample and the fines (Kc uncertainty were improved by capturing all data points within experimental errors. The massaction expression plots demonstrate that applying models outside the range of conditions used in model calibration greatly increases potential errors

Development of Space-Flight Compatible Room-Temperature Electronics for the Lynx X-Ray Microcalorimeter

We are studying the development of space-flight compatible room-temperature electronics for the Lynx x-ray microcalorimeter (LXM) of the Lynx mission. The baseline readout technique for the LXM is microwave SQUID multiplexing. The key modules at room temperature are the RF electronics module and the digital electronics and event processor (DEEP). The RF module functions as frequency converters and mainly consists of local oscillators and I/Q mixers. The DEEP performs demultiplexing and event processing, and mainly consists of field-programmable gate arrays, ADCs, and DACs. We designed the RF electronics and DEEP to be flight ready, and estimated the power, size, and mass of those modules. There are two boxes each for the RF electronics and DEEP for segmentation, and the sizes of the boxes are 13 in: 13 in: 9 in: for the RF electronics and 15.5 in: 11.5 in: 9.5 in: for the DEEP. The estimated masses are 25.1 kgbox for the RF electronics box and 24.1 kgbox for the DEEP box. The maximum operating power for the RF electronics is 141 W or 70.5 Wbox, and for the DEEP box is 615 W or 308 Wbox. The overall power for those modules is 756 W. We describe the detail of the designs as well as the approaches to the estimation of resources, sizes, masses, and powers

Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics

The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise.Comment: To appear in Proceedings of the SPIE, vol. 1069

Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry

Systematic Review to Inform a World Health Organization (WHO) Clinical Practice Guideline: Benefits and Harms of Needling Therapies for Chronic Primary Low Back Pain in Adults

PURPOSE Evaluate benefits and harms of needling therapies (NT) for chronic primary low back pain (CPLBP) in adults to inform a World Health Organization (WHO) standard clinical guideline. METHODS Electronic databases were searched for randomized controlled trials (RCTs) assessing NT compared with placebo/sham, usual care, or no intervention (comparing interventions where the attributable effect could be isolated). We conducted meta-analyses where indicated and graded the certainty of evidence. RESULTS We screened 1831 citations and 109 full text RCTs, yeilding 37 RCTs. The certainty of evidence was low or very low across all included outcomes. There was little or no difference between NT and comparisons across most outcomes; there may be some benefits for certain outcomes. Compared with sham, NT improved health-related quality of life (HRQoL) (physical) (2 RCTs; SMD = 0.20, 95%CI 0.07; 0.32) at 6 months. Compared with no intervention, NT reduced pain at 2 weeks (21 RCTs; MD = - 1.21, 95%CI - 1.50; - 0.92) and 3 months (9 RCTs; MD = - 1.56, 95%CI - 2.80; - 0.95); and reduced functional limitations at 2 weeks (19 RCTs; SMD = - 1.39, 95%CI - 2.00; - 0.77) and 3 months (8 RCTs; SMD = - 0.57, 95%CI - 0.92; - 0.22). In older adults, NT reduced functional limitations at 2 weeks (SMD = - 1.10, 95%CI - 1.71; - 0.48) and 3 months (SMD = - 1.04, 95%CI - 1.66; - 0.43). Compared with usual care, NT reduced pain (MD = - 1.35, 95%CI - 1.86; - 0.84) and functional limitations (MD = - 2.55, 95%CI - 3.70; - 1.40) at 3 months. CONCLUSION Based on low to very low certainty evidence, adults with CPLBP experienced some benefits in pain, functioning, or HRQoL with NT; however, evidence showed little to no differences for other outcomes

Systematic Review to Inform a World Health Organization (WHO) Clinical Practice Guideline: Benefits and Harms of Transcutaneous Electrical Nerve Stimulation (TENS) for Chronic Primary Low Back Pain in Adults

PURPOSE: To evaluate benefits and harms of transcutaneous electrical nerve stimulation (TENS) for chronic primary low back pain (CPLBP) in adults to inform a World Health Organization (WHO) standard clinical guideline. METHODS: We searched for randomized controlled trials (RCTs) from various electronic databases from July 1, 2007 to March 9, 2022. Eligible RCTs targeted TENS compared to placebo/sham, usual care, no intervention, or interventions with isolated TENS effects (i.e., combined TENS with treatment B versus treatment B alone) in adults with CPLBP. We extracted outcomes requested by the WHO Guideline Development Group, appraised the risk of bias, conducted meta-analyses where appropriate, and graded the certainty of evidence using GRADE. RESULTS: Seventeen RCTs (adults, n = 1027; adults ≥ 60 years, n = 28) out of 2010 records and 89 full text RCTs screened were included. The evidence suggested that TENS resulted in a marginal reduction in pain compared to sham (9 RCTs) in the immediate term (2 weeks) (mean difference (MD) = -0.90, 95% confidence interval  -1.54 to -0.26), and a reduction in pain catastrophizing in the short term (3 months) with TENS versus no intervention or interventions with TENS specific effects (1 RCT) (MD = -11.20, 95% CI -17.88 to -3.52). For other outcomes, little or no difference was found between TENS and the comparison interventions. The certainty of the evidence for all outcomes was very low. CONCLUSIONS: Based on very low certainty evidence, TENS resulted in brief and marginal reductions in pain (not deemed clinically important) and a short-term reduction in pain catastrophizing in adults with CPLBP, while little to no differences were found for other outcomes