Sol–gel carbons from ionothermal syntheses

Inorganic salt melts are used for the preparation of ceramics. It turns out that such ionothermal syntheses can also be employed in the chemistry of carbon. Carbon materials with improved application-relevant properties such as high surface area and large pore volume can be obtained. The way these properties are obtained strongly reminds on classic sol–gel synthesis, which displays a comparably easy approach toward such porous carbons. The central role of the solvent, i.e., the inorganic salt melt allows for variation of the chemical and morphological structure of carbon products. Interestingly, the use of inorganic salt melts may also give insights into the crystallization of carbon, if precursors are directly added to the hot melt, which additionally guarantees reorganizational dynamics to the pyrolysis intermediates

Investigation of Rheological Impacts on Sludge Batch 3 as Insoluble Solids and Wash Endpoints are Adjusted

The Defense Waste Processing Facility (DWPF) is currently processing and immobilizing radioactive sludge slurry into a durable borosilicate glass. The DWPF has already processed three sludge batches (Sludge Batch 1A, Sludge Batch 1B, and Sludge Batch 2) and is currently processing the fourth sludge batch (Sludge Batch 3). A sludge batch is defined as a single tank of sludge slurry or a combination of sludge slurries from different tanks that has been or will be qualified before being transferred to DWPF. As a part of the Sludge Batch 3 (SB3) qualification task, rheology measurements of the sludge slurry were requested at different insoluble solids loadings. These measurements were requested in order to gain insight into potential processing problems that may occur as the insoluble solids are adjusted up or down (by concentration or dilution) during the process. As a part of this study, a portion of the ''as received'' SB3 sample was washed with inhibited water (0.015 M NaOH and 0.015 M NaNO2) to target 0.5M Na versus a measured 1M Na in the supernate. The purpose of the ''washing'' step was to allow a comparison of the SB3 rheological data to the rheological data collected for Sludge Batch 2 (SB2) and to determine if there was a dependence of the yield stress and consistency as a function of washing. The ''as received'' SB3 rheology data was also compared to SB3 simulants prepared by the Simulant Development Program in order to provide guidance for selecting a simulant that is more representative of the rheological properties of the radioactive sludge slurry. A summary of the observations, conclusions are: (1) The yield stress and plastic viscosity increased as the weight percent insoluble solids were increased for the ''as received'' and ''washed'' SB3 samples, at a fixed pH. (2) For the same insoluble solids loading, the yield stress for the SB2 sample is approximately a factor of three higher than the ''as received'' SB3 sample. There also appears to be small difference in the plastic viscosity. This difference is probably due to the different Na concentrations of the slurries. (3) The yield stress for the SB2 sample at 17.5 wt. % insoluble solids loading is four times higher than the ''washed'' SB3 sample at 16.5 wt. % insoluble solids. There also appears to be small difference in the plastic viscosity. The differences for the yield stress and consistency can be explained by the differences in the Fe and Na concentrations of the sludge slurry and the anion concentrations of the resulting supernates. (4) The rheological properties (i.e. yield stress and plastic viscosity), as the insoluble solids are adjusted, for the ''as received'' and ''washed'' SB3 samples are different. The plastic viscosity curve for the ''as received'' SB3 sample was higher than the plastic viscosity curve for SB3 ''washed'' sample. The yield stress curve for the ''washed'' SB3 sample is slightly lower than the ''as received'' SB3 sample up until {approx}19 wt. % insoluble solids. The ''washed'' SB3 sample then exceeds the yield stress curve for the ''as received'' SB3 sample. This rheological behavior is probably due to the difference in the Na concentration of the supernate for the samples. (5) No unusual behavior, such as air entrainment, was noted for the ''as received'' SB3 sample. (6) The observed physical properties of the SB3 sample changed after washing. The ''washed'' SB3 sample entrained air readily at higher insoluble solids loadings (i.e. 14.1, 16.5, 19.5 wt. %) as it did for SB2. The air entrainment appeared to dissipate for the SB3 sample at the lower insoluble solids loadings (i.e. 9.7 and 11.7 wt. %). (7) The physical behavior of SB3 can be influenced by controlling the Na concentration in the supernate and the wt. % insoluble solids. The cause for the air entrainment in the ''washed'' SB3 sample could be due to a change in the particle size during the washing step. (8) The SB3 simulants prepared for the Simulant Development Program were approximately a factor of 1.6 to 4 times higher for yield stress and 2.6 to 4 times higher for the plastic viscosity over a similar range of insoluble solids loadings. The difference noted between the radioactive and simulant samples could be due to several factors including particle size, thermal treatment (i.e. aging of the sludge), shear history, etc

Evaluation and Calibration of SAPS 3 in Patients with COVID-19 Admitted to Intensive Care Units

info:eu-repo/semantics/publishedVersio

Biomass-Derived Heteroatom-Doped Carbon Aerogels from a Salt Melt Sol–Gel Synthesis and their Performance in Li–S Batteries

An ionothermal sol–gel strategy to synthesize hierarchically porous carbon aerogels doped with different heteroatoms is presented by using biomass precursors in a scalable process. Morphologically similar but chemically different materials are used to study the influence of heteroatoms in Li–S batteries. The materials show capacities as high as 1290 mAh g−1 in the first cycle using 50 wt % S loading. Heteroatom doping reduces the capacity fading and the polarization throughout cycling. Zeta potential measurements reveal positive surface charges for heteroatom-doped carbons and indicate attractive interactions with polysulfides causing reduced fading. A polysulfide-selective sorption study reveals strongly different adsorption behavior depending on the carbon’s chemical composition. Interestingly, the polysulfide fraction is also crucial. The results indicate that improved adsorption of long-chain polysulfides to doped carbons is related to improved capacity retention

DWPF Recycle Evaporator Shielded Cells Testing

Testing was performed to determine the feasibility and processing characteristics of evaporation of actual Defense Waste Processing Facility (DWPF) recycle material. Samples of the Off Gas Condensate Tank (OGCT) and Slurry Mix Evaporator Condensate Tank (SMECT) were transferred from DWPF to the Savannah River National Lab (SRNL) Shielded Cells and blended with De-Ionized (DI) water and a small amount of Slurry Mix Evaporator (SME) product. A total of 3000 mL of this feed was concentrated to approximately 90 mL during a semi-batch evaporation test of approximately 17 hours. One interruption occurred during the run when the feed tube developed a split and was replaced. Samples of the resulting condensate and concentrate were collected and analyzed. The resulting analysis of the condensate was compared to the Waste Acceptance Criteria (WAC) limits for the F/H Effluent Treatment Plant (ETP). Results from the test were compared to previous testing using simulants and OLI modeling. Conclusions from this work included the following: (1) The evaporation of DWPF recycle to achieve a 30X concentration factor was successfully demonstrated. The feed blend of OGCT and SMECT material was concentrated from 3000 mL to approximately 90 mL during testing, a concentration of approximately 33X. (2) Foaming was observed during the run. Dow Corning 2210 antifoam was added seven times throughout the run at 100 parts per million (ppm) per addition. The addition of this antifoam was very effective in reducing the foam level, but the impact diminished over time and additional antifoam was required every 2 to 3 hours during the run. (3) No scale or solids formed on the evaporator vessel, but splatter was observed in the headspace of the evaporator vessel. No scaling formed on the stainless steel thermocouple. (4) The majority of the analytes met the F/H ETP WAC. However, the detection limits for selected species (Sr-90, Pu-238, Pu-240, Am-243, and Cm-244) exceeded the ETP WAC limits. (5) I-129 was calculated to have exceeded the ETP WAC limits based on an assumed Decontamination Factor (DF) of 1 during evaporation. (6) The DF for most species was limited by the detection limits of the sample analysis. Based on iron, manganese, total alpha, total beta, and other species, very low entrainment was noted and evaporator DF was >10,000 for non-volatile species. (7) Very low DF's were obtained for selected species, especially mercury and formate. These species are present as volatile compounds and will exceed ETP WAC limits if sufficient concentrations are in the evaporator feed. (8) The evaporator DF's for the radioactive test were in good agreement with simulant test results. Differences noted in the DF of selected species, such as Hg, were more likely attributed to analytical issues than differences in the performance of the two evaporators. (9) The simulant appeared to be conservative in terms of foaming and scaling characteristics of the evaporator. The initial spike in foaming that occurred during all simulant runs did not occur during the Shielded Cells run and overall foaminess after the start of the test was controlled by antifoam additions. The splatter that was deposited during the radioactive test was less than the simulant runs and was more easily removed. (10) The OLI model results were overly conservative due to the manner that entrainment of solids was incorporated into the model

Seasonality in Major Depressive Disorder: Effect of Sex and Age

Background: Aside from the concept of seasonal affective disorder, the evidence for a seasonal pattern (SP) of major depressive disorder (MDD) is controversial. Furthermore, the effect of sex and age is still unclear. Methods: This is a nationwide, registry-based study assessing all inpatient admissions in mental health hospitals due to MDD episodes according to ICD-10 (moderate (F32/33.1), severe (F32/33.2) and severe with psychotic features (F32/33.3)) in Austria across 14 years. Calculations were based on deviations from expected monthly admissions. Results: The sample comprised 231,824 hospitalisations (36.8% men) for MDD. A significant SP (p=0.001) in moderate and severe depressive episodes in both women and men with decreased admission rates in the summer months and December was detected. In psychotic depression a significant SP was only evidenced in women (p = 0.002, men: p = 0.291). Patients older than 55 years had a reduced SP compared to those being younger. Limitations: Only anonymised admission data of inpatient treatments were available. Hospitalization rates cannot fully be equated to the occurrence of MDD. Conclusions: The current study indicates a seasonal variation in MDD symptoms that may go beyond seasonal affective disorder. Knowledge about the predictability of depressive symptoms in patients should encourage preventive strategies

High energy pion-deuteron elastic scattering

High energy pion-deuteron elastic scatterin

MEASUREMENT AND PREDICTION OF RADIOLYTIC HYDROGEN PRODUCTION IN DEFENSE WASTE PROCESSING SLURRIES AT SAVANNAH RIVER SITE

This paper presents results of measurements and predictions of radiolytic hydrogen production rates from two actual process slurries in the Defense Waste Processing Facility (DWPF) at Savannah River Site (SRS). Hydrogen is a flammable gas and its production in nuclear facilities can be a safety hazard if not mitigated. Measurements were made in the Shielded Cells of Savannah River National Laboratory (SRNL) using a sample of Sludge Batch 3 (SB3) currently being processed by the DWPF. Predictions were made using published values for rates of radiolytic reactions producing H{sub 2} in aqueous solutions and the measured radionuclide and chemical compositions of the two slurries. The agreement between measured and predicted results for nine experiments ranged from complete agreement to 24% difference. This agreement indicates that if the composition of the slurry being processed is known, the rate of radiolytic hydrogen production can be reasonably estimated