EMSL: Nancy Foster-Mills's Publications

Liu C, JM Zachara, NS Foster, and J Strickland. 2007. "Kinetics of Reductive Dissolution of Hematite by Bioreduced Anthraquinone-2,6-disulfate." Environmental Science & Technology 41(22):7730-7735. doi:10.1021/es070768k Abstract The reductive dissolution of hematite (-Fe2O3) was investigated in a flow-through system using AH2DS, a reduced form of anthraquinone- 2,6 disulfonate (AQDS), which is often used as an electron shuttling compound in studies of dissimilatory microbial reduction of iron oxides. Influent flow-rate, pH, Fe(II) and phosphate concentrations were varied to investigate the redox reaction kinetics. The effluent AH2DS, AQDS, and Fe(II) concentrations changed significantly within the first half hour of AH2DS reaction with hematite and then gradually evolved toward steady-state. The steady-state rates decreased with increasing pH from 4.5 to 7.6 and decreased with decreasing flow-rate. The rates also decreased with increasing influent concentration of Fe(II) or phosphate that formed surface complexes at the experimental pH. Mineral surface properties, Fe(II) complexation reactions, and AQDS sorption on hematite surfaces were independently investigated for interpreting hematite reductive dissolution kinetics. AH2DS sorption to hematite was inferred from the parallel measurements of AQDS and AH2DS sorption to -Al2O3, a redox stable analog of -Fe2O3. Decreasing Fe(II) and increasing AH2DS sorption by controlling flow residence time, influent pH, Fe(II) and phosphate concentrations increased the rates of reductive dissolution. The rates were also affected by the redox reaction free energy when reductive dissolution approached equilibrium, as shown by the effect of increasing the influent concentration of Fe(II).

Autrey T, AK Brown, DM Camaioni, M Dupuis, NS Foster, and AD Getty. 2004. "Thermochemistry of Aqueous Hydroxyl Radical from Advances in Photoacoustic Calorimetry and ab Initio Continum Solvation Theory." Journal of the American Chemical Society 126(12):3680-3681. Abstract Photoacoustic signals from dilute (~30 mM) solutions of H2O2 were measured over the temperature range from 10-45 °C to obtain the reaction enthalpy and volume change for H2O2(aq) → 2 OH(aq) from which we ultimately determined ∆f G°, ∆f H° and partial molal volume, v°, of OH (aq). We find ∆r H*=*46.8 ± 1.4 kcal/mol, which is 4 kcal/mol smaller than the gas phase bond energy, and ∆ Vr = 6.5 ± 0.4 mL/mol. The v° for OH in water is 14.4 ± 0.4 mL/ml: smaller than the v° of water. Using ab intio continuum theory, the hydration free energy is calculated to be –3.9 ± 0.3 kcal/mol (for standard states in number density concentration units) by a novel approach devised to capture in the definition of the solute cavity the strength and specific interactions of the solute with a water solvent molecule. The shape of the cavity is defined by “rolling” a 3 dimensional electron density isocontour of water on the ab initio water-OH minimum interaction surface. The value of the contour is selected to reproduce the volume of OH in water. We obtain for OH(aq): ∆f H° = -0.2 ± 1.5 and ∆f G° = 5.8 ± 0.4 kcal/mol that are inagreement with literature values. The results provide confidence in the pulsed PAC technique for measuring aqueous thermochemistry of radicals and open the way to obtaining thermochemistry for most radicals that can be formed by reaction of OH with aqueous substrates while advancing the field of continuum solvation theory towards ab initio-defined solute cavities

Foster NS, SE Thompson, NB Valentine, JE Amonette, and TJ Johnson. 2004. "Identification of Sporulated and Vegetative Bacteria using Statistical Analysis of Fourier Transform Mid-Infrared Transmission Data ." Applied Spectroscopy 58(2):203-211. Abstract A combined mid-infrared spectroscopic/statistical modeling approach for the discrimination and identification, at the strain level, of both sporulated and vegetative bacterial samples is presented. Transmission mode spectra of bacteria dried on ZnSe windows were collected using a Fourier-transform mid-infrared (FTIR) spectrometer. Five Bacillus bacterial strains (B. atrophaeus 49337, B. globigii, B. thuringiensis ssp. kurstaki, B. subtilis 49780, and B. subtilis 6051) were used to construct a reference spectral library and to parameterize a four-step statistical model for the systematic identification of bacteria. The statistical methods used included principal-component analysis (PCA), classification and regression trees (CART), and Mahalanobis-distance calculations. Internal cross-validation studies successfully classified 100% of the samples into their correct physiological state (sporulated or vegetative) and identified 67% of the samples correctly as to their bacterial strain. Analysis of thirteen blind samples, which included reference and other bacteria, nonbiological materials, and mixtures of both nonbiological and bacterial samples, yielded comparable accuracy. The chief advantage of this approach is the accurate identification of unknown bacteria, including spores, in a matter of minutes.

Autrey T, SV Egerev, NS Foster, A Fokin, and O Ovchinnikov. 2003. "Counting Particles by Means of Optoacoustics: Potential Limits in Real Solutions." Review of Scientific Instruments 74(1, part 2):628-631. Abstract Counting Particles by Means of Optoacoustics: Potential Limits in Real Solutions

Thompson SE, NS Foster, TJ Johnson, NB Valentine, and JE Amonette. 2003. "Identification of Bacterial Spores using Statistical Analysis of Fourier Transform Infrared Photoacoustic Spectroscopy Data ." Applied Spectroscopy 57(8):893-899. Abstract Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) has been applied for the first time to the identification and speciation of bacterial spores. With minimal preparation the spores were deposited into the photoacoustic sample cup and their spectra recorded. A total of 40 different samples of 5 different strains of Bacillus spores were analyzed: Bacillus subtilis ATCC 49760, Bacillus atrophaeus ATCC 49337, Bacillus subtilis 6051, Bacillus thuringiensis ssp. kurstaki, and Bacillus globigii Dugway. The statistical methods used included principal-component analysis (PCA), classification and regression trees (CART), and Mahalanobis-distance calculations. Internal cross-validation studies successfully classify the spores according to their bacterial strain in 38 of 40 cases (95%) and 36 of 40 (90%) in cross-validation. Analysis of fifteen blind samples, which included library and other spores, and nonbacterial materials, resulted in correct strain classification the blind samples that were members of the library and correct rejection of the nonbacterial samples.

Foster NS, JW Day, RH Filby, AF Alford, and DL Rogers. 2002. "The Role of Na-Montmorillonite in the Evolution of Copper, Nickel, and Vanadyl Geoporphyrins During Diagenesis ." Organic Geochemistry 33(8):907-919. Abstract The Role of Clay Minerals During Diagenesis In The Evolution Of Copper, Nickel, and Vanadyl Geoporphyrins

Autrey T, NS Foster, DF Hopkins, and JM Price. 2001. "Tunable Ultraviolet Visible Photoacoustic Detection - Analysis of the Sensitivity and Selectivity Provided by a Xenon Flash Lamp." Analytica Chimica Acta 434(2):217-222. Abstract Tunable Ultraviolet Visible Photoacoustic Detection-An Analysis of the Sensitivity and Selectivity Provided by a Xenon Flash Lamp

Foster NS, JE Amonette, T Autrey, and JT Ho. 2001. "Detection of Trace Levels of Water in Oil by Photoacoustic Spectroscopy." Sensors and Actuators. B, Chemical 77(3):620-624. Abstract Detection of Trace Levels of Water in Oil by Photoacoustic Spectroscopy

Felmy AR, LM Onishi, NS Foster, JR Rustad, D Rai, and MJ Mason. 2000. "An Aqueous Thermodynamic Model for the Pb2+ -Na+ -K+ -Ca2+ -Mg2+ -H+ -Cl- SO42- H2O System to High Concentration: Application to WIPP Brines." Geochimica et Cosmochimica Acta 64(21):3615-3628. Abstract The development of an aqueous thermodynamic model for the Pb2+ -Na+ -K+ -Ca2+ -Mg2+ -Cl -SO42 -H2O system is presented which is valid to high ionic strengths at 25C. The model is based upon the equations of Pitzer and has been parameterized from existing solubility, osmotic, electromotive force (emf), and spectroscopic data. To accurately represent the aqueous thermodynamics of Pb2+ in high chloride solutions required the inclusion of four Pb chloride species (i.e., PbCI+,PbCI2(aq),PbCI3 and PbCI42) along with the necessary Pitzer ion-interaction parameters for these species with the major electrolyte ions. The reliability of the final equilibrium model is tested against experimental solubility data on PbCI2(c) and PbSO4(c) in high ionic strength Waste Isolation Pilot Plant (WIPP) brines obtained as part of this study. On an overall basis the model accurately predicted the aqueous speciation, based upon comparisons with our UV-Vis spectroscopy measurements, as well as the observed solubility's. The model also proved satisfactory in predicting the observed solid phase assemblages, with the possible exception of solutions high in KCI.

Small JR, NS Foster, JE Amonette, and T Autrey. 2000. "Listening to Colloidal Silica Samples: Simultaneous Measurement of Absorbed and Scattered Light Using Pulsed-Laser Photoacoustics." Applied Spectroscopy 54(8):1142-1150.