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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Role of NLR family pyrin domain-containing 3 inflammasome in the activation of pancreatic stellate cells

Highlights: • NLRP3 inflammasome was activated with the extension of activation time of PSCs. • LPS triggered PSCs activation through activating NLRP3 Inflammasome. • Inhibition of NLRP3 inflammasome mitigates the activation of PSCs. • NLRP3 inflammasome activates the TGF-β1/Smad3 signaling pathway in PSCs. NLRP3 inflammasome activation plays an important role in the development of pancreatic fibrosis. However, it is unclear whether the activation of the NLRP3 inflammasome is directly involved in the activation of Pancreatic stellate cells (PSCs). The aim of this study was to investigate the role and mechanism of the NLRP3 inflammasome in the activation of PSCs. In vivo, a rat model of chronic pancreatitis (CP) was induced by intravenous injection of dibutyltin dichloride (DBTC). In vitro, rat primary PSCs were isolated from pancreatic tissues and incubated with the NLRP3 inflammasome activator LPS, the NLRP3 inhibitor MCC950, or NLRP3 siRNA. The results showed that the expression of NLRP3, pro-Caspase-1, Caspase-1 and IL-18 was increased in the rat model of CP and during PSCs activation. LPS increased the protein levels of NLRP3, ASC, Caspase-1, IL-1β and IL-18 accompanied by the upregulation of α-SMA, Col I and FN expression. Moreover, MCC950 or NLPR3 siRNA decreased the expression of α-SMA, Col I, FN, TGF-β1 and p-Smad3. Furthermore, MCC950 reversed the LPS-induced upregulation of α-SMA, FN and Col Ⅰ expression in PSCs. This study revealed that the NLRP3 inflammasome is directly involved in the activation of PSCs in vivo and in vitro. Inhibiting NLRP3 suppresses the activation of PSCs through the TGF-β1/Smad3 pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Technetium Complexation with Multidentate Carboxylate-Containing Ligands: Trends in Redox and Solubility Phenomena

The chemistry of technetium (t 1/2 ( 99 Tc) = 2.11 × 10 5 years) is of particular importance in the context of nuclear waste disposal and historic contaminated sites. Polycarboxylate ligands may be present in some sites and are potentially capable of strong complexing interactions, thus increasing the solubility and mobility of 99 Tc under environmentally relevant conditions. This work aimed to determine the impact of five organic complexing ligands [L = oxalate, phthalate, citrate, nitrilotriacetate (NTA), and ethylenediaminetetraacetate (EDTA)] under anoxic, alkaline conditions (pH ≈ 9–13) on the solubility of technetium. X-ray absorption spectroscopy confirmed that TcO 2 (am,hyd) remained the solubility-controlling solid phase in undersaturation solubility experiments. Ligands with maximum coordination numbers (CN) ≥ 3 (EDTA, NTA, and citrate) exhibited an increase in solubility from pH 9 to 11, while ligands with CN ≤ 2 (oxalate and phthalate) at all investigated pH and CN ≥ 3 at pH ≈ 13 were outcompeted by hydrolysis reactions. Though most available thermodynamic values were determined under acidic conditions, these models satisfactorily explained high-pH undersaturation solubility of technetium for citrate and NTA, whereas experimental data for Tc(IV)–EDTA were highly overestimated. Finally, this work illustrates the predominance of hydrolysis under hyperalkaline conditions and provides experimental support for existing thermodynamic models of Tc–L except Tc–EDTA, which requires further research regarding aqueous speciation and solubility.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Densification and Immobilization of AgI-Containing Iodine Waste Forms Using Spark Plasma Sintering

Here in this study, porous Ag-xerogel (Ag-Xero), Ag-faujasite (Ag-FAU) zeolite, and Ag-mordenite (Ag-MOR) zeolite sorbents were loaded with iodine gas [I 2 (g)] under saturated conditions at 150 °C for 24 h, followed by densification and consolidation into monolithic waste forms using spark plasma sintering (SPS). For Ag-Xero materials, SPS pellets were made with as-loaded samples, while others were made with preheated (PH; 500 °C for 2 h) samples to help with densification. SPS processing was conducted at 50 MPa under different temperatures (T = 200–800 °C) for different times (t = 0.5–30 min), where eleven AgI-Xero samples, five AgI-FAU, and two AgI-MOR separate samples were produced. The primary goal was to look for the optimum processing parameters for each material to yield pellets with high iodine retentions, high densities, and low porosities while preventing AgI decomposition. The Ag-Xero showed the highest iodine loadings (qe = 470 mg g –1 ) compared to Ag-FAU (qe = 368 mg g –1 ) and Ag-MOR (qe = 108 mg g –1 ). Measured iodine concentrations were the highest in AgI-Xero pellets without PH, followed by AgI-Xero with PH, AgI-FAU, and then AgI-MOR. Silver utilization (I/Ag on a mol % basis) values were in the order of AgI-MOR ≈ AgI-Xero (no PH) > AgI-Xero (PH) > AgI-FAU. Chemical durabilities of SPS-densified AgI-Xero (PH) pellets were very favorable, with lower releases than SPS pellets made from AgI-Xero samples without PH. These results show promise for iodine waste form production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗