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Adsorption of U(VI) on 6 samples of natural Fe-rich sands from Oyster, VA was studied over a range of U(VI) concentrations (0.1–100 μM), pH values (3–7.6), and dithionite–citrate–bicarbonate (DCB) extractable amounts of Fe (3.1–12.3 μmol/g). Four modeling approaches were applied to represent the U(VI) adsorption data. Model I was a two-site, diffuse double layer, surface complexation model based on data for synthetic ferrihydrite [Geochim. Cosmochim. Acta 58 (1994) 5465–5478]. Considering the magnitude of approximations necessary for application of the laboratory-based model to natural sands, Model I was surprisingly accurate, as determined by the goodness of fit parameter, χ2/N of 53.1–22.2. Model II was based on the reactions and diffuse double layer treatment of Model I, but was calibrated to a portion of U(VI) adsorption data for each sand, and then used to predict adsorption data for the same sand under different experimental conditions. Model II did not increase the accuracy of the predictions made with Model I, χ2/N of 42.4–27.6. Models III and IV were four-site affinity spectrum models, without an explicit electric double layer model or explicit surface hydrolysis reactions. Model III was based on a discrete log K spectrum approach, and Model IV was obtained from adjusting all surface stability constants and site concentrations for all surface sites. Models III and IV represented the U(VI) adsorption data with the greatest accuracy, χ2/N ranged from 13.8 to 4.4. Model I provides evidence supporting the practice of using pure phase thermodynamic reaction constants for describing the adsorption characteristics of environmentally important sorbents in certain simple cases. Yet, affinity spectrum approaches (Models III and IV) become increasingly important as more accurate interpolation of adsorption data is necessary, the sorbent becomes increasingly complex, or the range of experimental conditions expands. [Copyright &y& Elsevier]

Abstract: Compact layers are used in dye-sensitized solar cells (DSSCs) to passivate transparent conducting oxides (TCOs). TCO passivation increases DSSC performance by reducing electrical loss from recombination at the TCO-electrolyte interface and by improving electrical contact between the TCO and TiO2 photoelectrode. A novel process for synthesis of 4.5nm colloidal TiO2 compact layer particles via acid hydrolysis of titanium isopropoxide was developed. DSSCs fabricated with the colloidal TiO2 compact layer, with no compact layer, and those with an RF-sputtered compact layer were evaluated. Relative to a DSSC with no compact layer, the colloidal compact layer improved the short-circuit current density, fill factor, and solar energy conversion efficiency by 17.6%, 4.4%, and 25.3%, respectively. Relative to the sputtered compact layer, the colloidal compact layer improved the short-circuit current density and solar energy conversion efficiency by 5.5% and 5.3%, respectively, with no significant change in the fill factor. The improved DSSC characteristics were attributed to increased shunt resistance due to decreased electrolyte reduction at the TCO-electrolyte interface and decreased series resistance due to improved electrical contact between the TCO and the TiO2 photoelectrode. [Copyright &y& Elsevier]

The current state-of-the-art dye loading process for modern dye-sensitized solar cells (DSCs), essentially unchanged for the last 24 years, entails dip-coating nanoporous TiO 2 photoelectrodes in a concentrated solution of dye for an average of 16 h. This process constitutes up to 80% of the fabrication time, leads to significant dye waste, and necessitates the use of organic solvents. A promising gas-phase deposition technique, coined Functionalized Carboxylate Deposition (FCD), was used to rapidly deposit a self-assembled monolayer of targeted α-carbon modified carboxylic acid containing dye molecules on TiO 2 photoelectrodes. The FCD process successfully reduced the dye loading time by 98% (i.e., 15–20 min compared to an average of 16 h). Moreover, the FCD-sensitized photoelectrodes produced DSCs with equivalent or higher efficiencies than dip-coating for the dyes used (both in this study and by other researchers). The performance of FCD dye sensitization in this study indicates its potential applicability as a foundational technology for rapid fabrication of efficient DSCs. [ABSTRACT FROM AUTHOR]

Highlights: [•] The toxicokinetic behavior of α-KgCN in swine was investigated. [•] Measuring plasma α-KgCN provides definitive confirmation of cyanide exposure. [•] Treatment of cyanide poisoning with cobinamide renders α-KgCN an ineffective diagnostic marker. [ABSTRACT FROM AUTHOR]

An in vitro study was conducted to determine effects of reducing pH of porcine in vitro fermentation medium on compositions of glucosinolate degradation products and porcine in vitro fermentation characteristics for solvent-extracted canola meal (SECM) and cold-pressed canola cake (CPCC). Two canola co-products were subjected to porcine in vitro fermentation for 72 h. Accumulated gas production during microbial fermentation was recorded and modeled to estimate kinetics of gas production. Glucosinolate degradation products after microbial fermentation were determined and fermentation medium pH after incubation was recorded. Total and individual volatile fatty acids (VFA) concentrations per unit weight of dry matter (DM) of feedstuffs were determined. On DM basis, SECM and CPCC contained 6.15 and 11.1 µmol/g of glucosinolates, respectively. Goitrin concentration for CPCC was lower (P < 0.05) than that for SECM. Isothiocyanate and indole-3-acetonitrile concentrations for CPCC were lower (P < 0.05) than those for SECM, whereas thiocyanate concentration for CPCC was greater (P < 0.05) than that for SECM. A reduction in fermentation medium pH from 6.2 to 5.2 increased (P < 0.05) goitrin and indole-3-acetonitrile concentrations and decreased (P < 0.05) isothiocyanates concentration for SECM, but did not affect concentration of these 2 glucosinolate degradation products for CPCC. Fermentation medium pH after in vitro fermentation for SECM tended to be greater (P = 0.081) than that for CPCC. Canola co-product type and fermentation medium pH did not interact on gas production parameters. However, a reduction in fermentation medium pH from 6.2 to 5.2 resulted in increased (P < 0.05) lag time and reduced (P < 0.05) fractional rate of degradation and total gas production. Canola co-product type and fermentation medium pH did not interact on total or individual VFA production per gram of DM of feedstuff fermented. However, reducing fermentation medium pH from 6.2 to 5.2 increased (P < 0.05) total VFA and acetate productions, and tended to reduce (P = 0.083) branched-chain VFA production SECM and CPCC. In conclusion, a reduction in fermentation medium pH from 6.2 to 5.2 resulted in increased production of goitrin and indole-3-acetonitriles from SECM-derived glucosinolates, but did not affect production of thiocyanate from SECM-derived glucosinolates. Glucosinolates in CPCC were less affected by the fermentation medium pH used in the current study. It appears that there are other factors other than pH that affect the degradation of canola-derived glucosinolates by microorganisms from hindgut of pigs. • Glucosinolates in canola cake were less degradable than those in canola meal. • Reduction in fermentation medium pH increased nitrile production from canola meal. • Reduction in fermentation medium pH increased goitrin production from canola meal. • Reduction in fermentation medium pH unaffected nitrile production from canola cake. • Reduction in fermentation medium pH unaffected goitrin production from canola cake. [ABSTRACT FROM AUTHOR]