Soret Effect Study on High-Pressure CO2-Water Solutions Using UV-Raman Spectroscopy and a Concentric-Tube Optical Cell

Spatially resolved deep-UV Raman spectroscopy was applied to solutions of CO2 and H2O (or D2O), which were subject to a temperature gradient in a thermally regulated high-pressure concentric-tube Raman cell in an attempt to measure a Soret effect in the vicinity of the critical point of CO2. Although Raman spectra of solutions of CO2 dissolved in D2O at 10 MPa and temperatures near the critical point of CO2 had adequate signal-to-noise and spatial resolution to observe a Soret effect with a Soret coefficient with magnitude of |ST| > 0.03, no evidence for an effect of this size was obtained for applied temperature gradients up to 19oC. The presence of 1 M NaCl did not make a difference. In contrast, the concentration of CO2 dissolved in H2O was shown to vary significantly across the temperature gradient when excess CO2 was present, but the results could be explained simply by the variation in CO2 solubility over the temperature range and not to kinetic factors. For mixtures of D2O dissolved in scCO2 at 10 MPa and temperatures close to the critical point of CO2, the Raman peaks for H2O were too weak to measure with confidence even at the limit of D2O solubility

Final Report for the Study on S-Implanted Alloy 22 in 1 M NaCl Solutions

The objective of this study was to examine the effects of high levels of S in the near-surface region on the passivity of Alloy 22, a corrosion resistant Ni-Cr-Mo alloy, in deaerated 1 M NaCl solution. Near-surface concentrations of S up to 2 at.% were achieved in Alloy 22 test specimens by implanting them with S. The S-implanted samples were then evaluated in short-term electrochemical tests in the salt solution and subsequently analyzed with X-ray Photoelectron Spectroscopy (XPS) for film thickness and composition. Specimens tested included non-implanted and annealed Alloy 22 samples, samples implanted with S, and “blanks” implanted with Ar as an ion that would simulate the “damage” of S implantation without the chemical effect. A sample of S-implanted Alloy 22 was also exposed to solution for 29 days and analyzed for evidence of S accumulation at the surface over longer times

Integrated Disposal Facility FY2011 Glass Testing Summary Report

Pacific Northwest National Laboratory was contracted by Washington River Protection Solutions, LLC to provide the technical basis for estimating radionuclide release from the engineered portion of the disposal facility (e.g., source term). Vitrifying the low-activity waste at Hanford is expected to generate over 1.6 x 10{sup 5} m{sup 3} of glass (Certa and Wells 2010). The volume of immobilized low-activity waste (ILAW) at Hanford is the largest in the DOE complex and is one of the largest inventories (approximately 8.9 x 10{sup 14} Bq total activity) of long-lived radionuclides, principally {sup 99}Tc (t{sub 1/2} = 2.1 x 10{sup 5}), planned for disposal in a low-level waste (LLW) facility. Before the ILAW can be disposed, DOE must conduct a performance assessment (PA) for the Integrated Disposal Facility (IDF) that describes the long-term impacts of the disposal facility on public health and environmental resources. As part of the ILAW glass testing program PNNL is implementing a strategy, consisting of experimentation and modeling, in order to provide the technical basis for estimating radionuclide release from the glass waste form in support of future IDF PAs. The purpose of this report is to summarize the progress made in fiscal year (FY) 2011 toward implementing the strategy with the goal of developing an understanding of the long-term corrosion behavior of low-activity waste glasses

Epsilon Metal Summary Report FY 2011

The Epsilon-metal ({var_epsilon}-metal) phase was selected in FY 2009 as a potential waste form to for immobilizing the noble metals found in the undissolved solids + aqueous stream, and the soluble Tc from ion-exchange process, each resulting from proposed aqueous reprocessing. {var_epsilon}-metal phase is observed in used nuclear fuel and the natural reactors of Oklobono in Gabon, where the long-term corrosion behavior was demonstrated. This makes {var_epsilon}-metal a very attractive waste form. Last fiscal year, {var_epsilon}-metal was successfully fabricated by combining the five-metals, Mo, Ru, Rh, Pd and Re (surrogate for Tc), into pellets followed by consolidation with an arc melter. The arc melter produced fully dense samples with the epsilon structure. However, some chemistry differences were observed in the microstructure that resulted in regions rich in Re and Mo, and others rich in Pd, while Ru and Rh remained fairly constant throughout. This year, thermal stability (air), and corrosion testing of the samples fabricated by arc melting were the main focus for experimental work. Thermal stability was measured with a differential scanning calorimeter - thermogravimetric analyzer, by both ramp heating as well as step heating. There is clear evidence during the ramp heating experiment of an exothermic event + a weight loss peak both beginning at {approx}700 C. Step heating showed an oxidation event at {approx}690 C with minimal weight gain that occurs just before the weight loss event at 700 C. The conclusion being that the e-metal begins to oxidize and then become volatile. These findings are useful for considering the effects of voloxidation process. Three different pellets were subjected to electrochemical testing to study the corrosion behavior of the epsilon-metal phase in various conditions, namely acidic, basic, saline, and inert. Test was done according to an interim procedure developed for the alloy metal waste form. First an open circuit potential was measured, followed by linear polarization sweeps. The linear polarization sweep range was the Tafel equation was fit to the linear polarization sweep data to determine the corrosion rate of each pellet in each test solution. The average calculated corrosion rates of the three pellets according to solution conditions were: -1.91 x 10{sup -4} mm/yr (0.001 M NaOH), -1.48 x 10{sup -3} mm/yr (0.01 M NaCl), -8.77 x 10{sup -4} mm/yr (0.001 M H{sub 2}SO{sub 4}), -2.09 x 10{sup -3} mm/yr (0.001 M NaOH + 0.01 M NaCl), and -1.54 x 10{sup -3} mm/yr (0.001 M H{sub 2}SO{sub 4} + 0.01 M NaCl). Three single-pass flow through (SPFT) test were conducted at a flow rate of 10 ml/day, at 90 C, and pH of 2.5, 7.0, and 9.0 for up to 322 days. Results of the tests indicate that dissolution rates were 5 x 10{sup -4} g m{sup 2} d{sup -1} at pH 9.0, 1.2 x 10{sup -4} g m{sup -2} d{sup -1} at pH 7.0, and 2 x 10{sup -4} g m{sup -2} d{sup -1} at pH 2.5. The sample used for the pH 7.0 SPFT test contains extra Re compared to samples used for the other two SPFT test, which came from a single pellet. The corrosion data measured this year indicate that the {var_epsilon}-metal phase is chemically durable. The two chemically different phases, but structurally the same, behave differently during dissolution according to the microstructure changes observed in both the electrochemical and in SPFT test. Characterization of the test specimens after testing suggests that the dissolution is complex and involves oxidative dissolution followed by precipitation of both oxide and metallic phases. These data suggest that the dissolution in the electrochemical and SPFT tests is different; a process that needs further investigation

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia:a systematic review and individual participant data meta-analysis

BACKGROUND: The optimal interface for the delivery of home non-invasive ventilation (NIV) to treat chronic respiratory failure has not yet been determined. The aim of this individual participant data (IPD) meta-analysis was to compare the effect of nasal and oronasal masks on treatment efficacy and adherence in patients with COPD and obesity hypoventilation syndrome (OHS). METHODS: We searched Medline and Cochrane Central Register of Controlled Trials for prospective randomised controlled trials (RCTs) of at least 1 month's duration, published between January 1994 and April 2019, that assessed NIV efficacy in patients with OHS and COPD. The main outcomes were diurnal PaCO2, PaO2 and NIV adherence (PROSPERO CRD42019132398). FINDINGS: Of 1576 articles identified, 34 RCTs met the inclusion criteria and IPD were obtained for 18. Ten RCTs were excluded because only one type of mask was used, or mask data were missing. Data from 8 RCTs, including 290 IPD, underwent meta-analysis. Oronasal masks were used in 86% of cases. There were no differences between oronasal and nasal masks for PaCO2 (0.61 mm Hg (95% CI -2.15 to 3.38); p=0.68), PaO2 (-0.00 mm Hg (95% CI -4.59 to 4.58); p=1) or NIV adherence (0·29 hour/day (95% CI -0.74 to 1.32); p=0.58). There was no interaction between the underlying pathology and the effect of mask type on any outcome. INTERPRETATION: Oronasal masks are the most used interface for the delivery of home NIV in patients with OHS and COPD; however, there is no difference in the efficacy or tolerance of oronasal or nasal masks

Alternative Electrochemical Salt Waste Forms, Summary of FY/CY2011 Results

This report summarizes the 2011 fiscal+calendar year efforts for developing waste forms for a spent salt generated in reprocessing nuclear fuel with an electrochemical separations process. The two waste forms are tellurite (TeO2-based) glasses and sol-gel-derived high-halide mineral analogs to stable minerals found in nature

Rh-Based Mixed Alcohol Synthesis Catalysts: Characterization and Computational Report

The U.S. Department of Energy is conducting a program focused on developing a process for the conversion of biomass to bio-based fuels and co-products. Biomass-derived syngas is converted thermochemically within a temperature range of 240 to 330°C and at elevated pressure (e.g., 1200 psig) over a catalyst. Ethanol is the desired reaction product, although other side compounds are produced, including C3 to C5 alcohols; higher (i.e., greater than C1) oxygenates such as methyl acetate, ethyl acetate, acetic acid and acetaldehyde; and higher hydrocarbon gases such as methane, ethane/ethene, propane/propene, etc. Saturated hydrocarbon gases (especially methane) are undesirable because they represent a diminished yield of carbon to the desired ethanol product and represent compounds that must be steam reformed at high energy cost to reproduce CO and H2. Ethanol produced by the thermochemical reaction of syngas could be separated and blended directly with gasoline to produce a liquid transportation fuel. Additionally, higher oxygenates and unsaturated hydrocarbon side products such as olefins also could be further processed to liquid fuels. The goal of the current project is the development of a Rh-based catalyst with high activity and selectivity to C2+ oxygenates. This report chronicles an effort to characterize numerous supports and catalysts to identify particular traits that could be correlated with the most active and/or selective catalysts. Carbon and silica supports and catalysts were analyzed. Generally, analyses provided guidance in the selection of acceptable catalyst supports. For example, supports with high surface areas due to a high number of micropores were generally found to be poor at producing oxygenates, possibly because of mass transfer limitations of the products formed out of the micropores. To probe fundamental aspects of the complicated reaction network of CO with H2, a computational/ theoretical investigation using quantum mechanical and ab initio molecular dynamics calculations was initiated in 2009. Computational investigations were performed first to elucidate understanding of the nature of the catalytically active site. Thermodynamic calculations revealed that Mn likely exists as a metallic alloy with Rh in Rh-rich environments under reducing conditions at the temperatures of interest. After determining that reduced Rh-Mn alloy metal clusters were in a reduced state, the activation energy barriers of numerous transition state species on the catalytically active metal particles were calculated to compute the activation barriers of several reaction pathways that are possible on the catalyst surface. Comparison of calculations with a Rh nanoparticle versus a Rh-Mn nanoparticle revealed that the presence of Mn enabled the reaction pathway of CH with CO to form an adsorbed CHCO species, which was a precursor to C2+ oxygenates. The presence of Mn did not have a significant effect on the rate of CH4 production. Ir was observed during empirical catalyst screening experiments to improve the activity and selectivity of Rh-Mn catalysts. Thus, the addition of Ir to the Rh-Mn nanoparticles also was probed computationally. Simulations of Rh-Mn-Ir nanoparticles revealed that, with sufficient Ir concentrations, the Rh, Mn and Ir presumably would be well mixed within a nanoparticle. Activation barriers were calculated for Rh-Mn-Ir nanoparticles for several C-, H-, and O-containing transitional species on the nanoparticle surface. It was found that the presence of Ir opened yet another reactive pathway whereby HCO is formed and may undergo insertion with CHx surface moieties. The reaction pathway opened by the presence of Ir is in addition to the CO + CH pathway opened by the presence of Mn. Similar to Mn, the presence of Ir was not found to not affect the rate of CH4 production

Completion of Hepatitis C Virus Replication Cycle in Heterokaryons Excludes Dominant Restrictions in Human Non-liver and Mouse Liver Cell Lines

Hepatitis C virus (HCV) is hepatotropic and only infects humans and chimpanzees. Consequently, an immunocompetent small animal model is lacking. The restricted tropism of HCV likely reflects specific host factor requirements. We investigated if dominant restriction factors expressed in non-liver or non-human cell lines inhibit HCV propagation thus rendering these cells non-permissive. To this end we explored if HCV completes its replication cycle in heterokaryons between human liver cell lines and non-permissive cell lines from human non-liver or mouse liver origin. Despite functional viral pattern recognition pathways and responsiveness to interferon, virus production was observed in all fused cells and was only ablated when cells were treated with exogenous interferon. These results exclude that constitutive or virus-induced expression of dominant restriction factors prevents propagation of HCV in these cell types, which has important implications for HCV tissue and species tropism. In turn, these data strongly advocate transgenic approaches of crucial human HCV cofactors to establish an immunocompetent small animal model

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery