Donald Siegel

... YW, and Wold, RJ, 1975, Geodetic, geological, and geophysical evidence for ... Rayleigh-type fractionation and a kinetic model: American Journal of Science, v ... studies: Geochemistry and analytical determination,: in Proceedings, Groundwater Geochemistry Conference: Denver ...

ABSTRACT According to at least one aspect of the present invention, an ammonia borane containing hydrogen storage material is provided to be present with substantially reduced formation of borazine or diborane. In at least one embodiment, the hydrogen storage material includes at least one ammonia borane (NH3BH3); and at least one amide of the formula M(NH2)x, wherein M is a cationic element or a combination of two or more cationic elements from groups 1 to 14 of the periodic table and x represents a total cationic charge to charge balance M.

ABSTRACT A method of forming a material for reversible hydrogen storage Within a storage tank includes charging a mixture of a metal amide and a metal hydride to the storage tank, and chemically reacting the mixture at a reaction condition Within the storage tank to form a thermally conducting composite material situated in the storage tank and for reversibly storing hydrogen. The composite material includes a three-dimensional and interconnected framework including a conductive metal. A method for reversibly storing hydrogen includes providing a storage tank and in situ chemically forming a composite material by charging a mixture of a metal amide and a metal hydride to the storage tank and chemically reacting the mixture at a reaction condition to form a thermally conducting composite material including a metal hydride and a substantially unreactive elemental metal framework. Hydrogen is absorbed into the composite material and is desorbed from the composite material.

A new integrated catchment model for salinity has been developed to assess the transport of road salt from upland areas in watersheds to streams using readily accessible landscape, hydrologic, and meteorological data together with reported salt applications. We used Fishkill Creek (NY) as a representative watershed to test the model. Results showed good agreement between modeled and measured stream water chloride concentrations. These results suggest that a dominant mode of catchment simulation that does not entail complex deterministic modeling is an appropriate method to model salinization and to assess effects of future applications of road salt to streams. We heuristically increased and decreased salt applications by 100% and results showed that stream chloride concentrations increased by 13% and decreased by 7%, respectively. The model suggests that future management of salt application can reduce environmental concentrations, albeit over some time.► A new Integrated Catchment Model (INCA-Cl) is developed to simulate salinity. ► Road salt application is important in controlling stream chloride concentration. ► INCA-Cl can be used to manage and forecast the input and transport of chloride to the rivers.

The potential of emerging technologies such as fuel cells (FCs) and photovoltaics for environmentally-benign power generation has sparked renewed interest in the development of novel materials for high density energy storage. For applications in the transportation sector, the demands placed upon energy storage media are especially stringent, as a potential replacement for fossil-fuel-powered internal combustion engines -- namely, the proton exchange membrane FC -- utilizes hydrogen as a fuel. Although hydrogen has about three times the energy density of gasoline by weight, its volumetric energy density (even at 700 bar) is roughly a factor of six smaller. Consequently, the safe and efficient storage of hydrogen has been identified as one of the key materials-based challenges to realizing a transition to FC vehicles. This talk will present an overview of recent efforts at Ford aimed at developing new materials for reversible, solid state hydrogen storage. A tight coupling between first-principles modeling and experiments has greatly accelerated our efforts, and several examples illustrating the benefits of this approach will be presented.

ABSTRACT Li-O2 batteries have the potential to achieve a much higher (3-5x)1 specific energy than current state of the art Li-ion batteries, which could allow battery-powered electric vehicles to compete with traditional gas-powered cars.2 The greatest barriers to Li-O2 technology are limited cycle life and low battery efficiency. A better understanding of the mechanism of discharge product formation and dissolution would help to overcome these barriers. Controlled observation of discharge-product (Li2O2) morphology may provide insight into reaction mechanisms. Several reports of the morphology of electrochemically formed Li2O2 show the size and shape of Li2O2 particles and relate these characteristics to battery performance3,4,5. Typically, the discharge products are discussed as either small particles4 or nanosheets5 on the order of 10 nm, or larger toroidal shapes on the order of 100 nm. The small particles have a lower overpotential during recharge than the larger particles. If Li2O2 is formed by an elementary electron exchange, then the formation of large particles suggests a discharge mechanism where electrons travel over hundreds of nanometers, which suggests a complex charge transfer mechanism since bulk Li2O2is an electrical insulator. In this talk we will report a study of the rate dependence of Li-O2 discharge-product morphology during first discharge. At each of four rates ten independent Li-O2 cells were discharged to provide a statistically significant assessment of discharge capacity. Figure 1 shows the variation of discharge capacity with discharge rate with the inset showing the discharge curves at 0.2 mA/cm2. Cathodes with near-average capacity were selected for further characterization. X-ray diffraction showed that Li2O2 was the primary crystalline discharge product at all rates. Scanning electron microscopy (SEM) showed that the Li2O2 deposits comprised roughly cylindrical particles at lower rates, and needle-like particles at the highest rate. The cylinders had constant radii at different rates, which were comparable to the lengths of the needles. The heights of cylindrical products appeared to rise with decreasing rate. Figure 2 shows the volume of the Li2O2 particles as a function of discharge rate. The inset SEM images show the cylinders at end-of-discharge within 1 µm x 1 µm areas. The characteristic shapes (and aspect ratios) of particles yielded by image processing of > 25 particles from each electrode are also shown schematically. A nucleation and growth mechanism for Li2O2will be proposed and the impacts of this mechanism on battery performance will be discussed. 1. Lu, Y. C., B. M. Gallant, et al. (2013). Energy & Environmental Science 6(3): 750-768. 2. Christensen, J., P. Albertus, et al. (2012). J. Electrochem. Soc. 159(2): R1-R30. 3. Adams, B. D., C. Radtke, et al. (2013). Energy & Environmental Science 6(6): 1772-1778. 4. Gallant, B. M., D. G. Kwabi, et al. (2013). Energy & Environmental Science 6(8): 2518-2528. 5. Xu, J. J., Z. L. Wang, et al. (2013). Nature Communications 4.

A reversible hydrogen storage composition having an empirical formula of: Li.sub.(x+z)N.sub.xMg.sub.yB.sub.zH.sub.w where 0.4.ltoreq.x.ltoreq.0.8; 0.2.ltoreq.y.ltoreq.0.6; 0<z.ltoreq.0.4, x+y+z=1 and "w" varies from 0 to 2x+2y+4z. This composition shows greater low temperature reversible hydrogen storage compared to binary systems such as MgH.sub.2--LiNH.sub.2.

Using large-scale Density Functional calculations in conjunction with the nudged elastic band method for transition state finding, we investigate grain boundary (GB) segregation and the activation energy barriers for diffusion (Δ E) of C in bulk Ni and at a Σ 3 GB. For bulk diffusion we find Δ E = 1.62 eV, in excellent agreement with experiment (1.54--1.71 eV). For GB diffusion, a surprisingly large anisotropy was found in the Δ E's parallel- and perpendicular to the GB tilt axis. Diffusion along the tilt axis is relatively ``fast,'' with a small Δ E 0.5 eV, while diffusion perpendicular to the tilt axis is characterized by a Δ E comparable to that of bulk diffusion. Assuming the same prefactor, this would correspond to a difference of ˜20 orders of magnitude in the diffusivity at room temperature! Although in a real GB there would be defects which would reduce this anisotropy dramatically, it is nonetheless instructive to see how large the anisotropy could be in a perfect boundary. We discuss the geometric factors which cause diffusion at this boundary to be so much more facile along the tilt axis.

We propose a set of thermodynamic guidelines aimed at facilitating more robust screening of hydrogen storage reactions. The utility of the guidelines is illustrated by reassessing the validity of reactions recently proposed in the literature and through vetting a list of more than 20 candidate reactions based on destabilized LiBH4 and Ca(BH4)2 borohydrides. Our analysis reveals several reactions having both

Mountain streams are a common source in Central America for community water supplies (CWS). These streams become dewatered by the CWS during dry season low flows, with potential impacts on hydraulic gradients, hyporheic exchange flow, terrestrial-aquatic linkages, and nutrient dynamics, which may ultimately affect aquatic and riparian micro-ecosystems. We are presenting preliminary results of a study conducted in Buena Vista, a village in Yoro, Honduras where the mountain stream was instrumented and manipulated to measure impacts of a CWS. Piezometric head and stream water levels were taken at 7 cross-sections along 30 m of step-pool stream, and water quality samples were retrieved from 48 pairs of riparian and stream piezometers and monitoring wells. We computed vertical hydraulic gradients, zones of hyporheic upwelling and downwelling, and nutrient patterns, and their change with streamflow. Streamflow ranged from 30 L/s in the wet-season high flow to about 2 L/s in the dry-season low flow, and were dewatered to about 1 L/s. A HEC- RAS water-surface profile model was calibrated to observed stages to establish gradients along the entire reach, and river head was then input as a boundary condition into a MODFLOW groundwater model to examine patterns of hyporheic exchange. Changes in hydraulic gradients and fluxes are compared with baseline conditions during the dry season low flow without dewatering. Noticeable changes in hydraulic gradient occurred between high and low flows, but changes in low flow to dewatered flow were negligible. Lengths and location of hyporheic upwelling and downwelling zones shifted slightly with changes in flow, but again the dewatering had a minor impact. Concentrations of nitrate, sulfate, chloride, fluoride and dissolved oxygen were detected in the hyporheic zone, the stream water, and adjacent ground water. We are exploring mixing models to assess the extent to which hyporheic exchange migrated to and from the creek to adjacent riparian zones.

ABSTRACT Metal-O2 batteries are considered as an improvement upon current battery technologies due to their high theoretical energy densities. In particular, Mg-O2 batteries have one of the highest predicted theoretical specific energy densities [1]. Mg-O2 batteries have been previously demonstrated using aqueous electrolytes. However, aqueous chemistries are generally non-rechargeable. and more recent studies have targeted secondary systems based on non-aqueous Mg-conducting electrolytes in the context of Mg-ion and Mg-sulfur batteries [2]. Although Shiga et. al. reported the first rechargeable Mg-O2 battery using a non-aqueous electrolyte [3], the nature of the discharge product remains poorly understood. Our goal is to understand the discharge characteristics of Mg-O2 batteries using non-aqueous electrolytes. Here we discuss our progress in characterizing the discharge products in Mg-O2 batteries. Figure 1 shows a discharge curve for such a battery using 0.05M Mg(BH4)2 in dimethoxyethane as the electrolyte. This electrolyte has been shown to reversibly deposit and dissolve Mg [4]. A voltage plateau of 1.1 V is observed, similar to previously reported non-aqueous Mg-O2 battery [3]. The measured cell voltage is low compared to the theoretical voltage expected from formation of MgO and MgO2 (2.95V and 2.91V vs. Mg/Mg2+, respectively) [5]. The carbon cathodes were characterized by x-ray diffraction and Raman spectroscopy. It was observed that MgCO3 was the dominant Mg compound. MgCO3 formation is likely due to reactions with the carbon cathode or with the electrolyte. [1] Zu, C.-X., & Li, H. "Thermodynamic analysis on energy densities of batteries". Energy & Environmental Science, 4 (2011) 2614. [2] Muldoon, J., Bucur, C. B., Oliver, A. G., Sugimoto, T., Matsui, M., Kim, H. S., et al. "Electrolyte roadblocks to a magnesium rechargeable battery". Energy & Environmental Science, 5 (2012) 5941. [3] T. Shiga, Y. Hase, Y. Kato, M. Inoue, K. Takechi, " A rechargeable non-aqueous Mg-O2 battery". Chemistry Communications, 49 (2013) 9152. [4] R. Mohtadi, M. Matsui, T.S. Arthur, S.-J. Hwang, “Magnesium borohydride: from hydrogen storage to magnesium battery.” Angewandte Chemie International Edition in English 51 (2012) 9780. [5] Vannerberg, N. “Peroxides, Superoxides, and Ozonides of the Metals of Group Ia, IIa, and IIb”, Progress in Inorganic Chemistry, 4th ed.

Reversals in hydraulic head and extensive methane losses were identified during a drought cycle from changes in hydraulic-head and dissolved-methane profiles in peat, Glacial Lake Agassiz Peatlands, northern Minnesota, United States. During the summer 1990 drought, regional ground water discharged from the mineral soil underlying the peat to raised bogs. Concentrations of dissolved CH4 in pore water showed that much of the peat column was supersaturated with respect to a reference standard of I atm partial pressure CH4. By the summer of 1991, the severity of the drought lessened, and the upper peat column was resaturated with precipitation-derived water. Ground-water flow was then controlled by local, precipitation-driven, recharge flow systems, and the regional ground water that was discharged affected only the peat immediately above the mineral soil-peat interface. In contrast, during the summer of 1991, concentrations of dissolved CH4 in pore water were all undersaturated with respect to 1 atm partial pressure CH4. The decrease in the amount of dissolved CH4, in the pore water from the summer of 1990 to the summer of 1991 probably was caused by changes in the CH4 flux and degassing to the unsaturated zone and to a lesser extent by changes in the partial pressure of gaseous CH4 in the peat as the peat volume increased with expansion as it resaturated.

Using density functional theory we examine the crystal structure and the finite-temperature thermodynamics of formation and dehydrogenation for the new quaternary hydride Li4BN3H10. Two recent studies based on X-ray and neutron diffraction have reported three bcc crystal structures for this phase. While these structures possess identical space groups and similar lattice constants, internal coordinate differences result in bond length discrepancies

Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials.

Metal-organic frameworks (MOFs) are an emerging class of microporous, crystalline materials with potential applications in the capture, storage, and separation of gases. Of the many known MOFs, MOF-5 has attracted considerable attention because of its ability to store gaseous fuels at low pressure with high densities. Nevertheless, MOF-5 and several other MOFs exhibit limited stability upon exposure to reactive species such as water. The present study quantifies the impact of humid air exposure on the properties of MOF-5 as a function of exposure time, humidity level, and morphology (i.e., powders vs pellets). Properties examined include hydrogen storage capacity, surface area, and crystallinity. Water adsorption/desorption isotherms are measured using a gravimetric technique; the first uptake exhibits a type V isotherm with a sudden increase in uptake at ∼50% relative humidity. For humidity levels below this threshold only minor degradation is observed for exposure times up to several hours, suggesting that MOF-5 is more stable than generally assumed under moderately humid conditions. In contrast, irreversible degradation occurs in a matter of minutes for exposures above the 50% threshold. Fourier transform infrared spectroscopy indicates that molecular and/or dissociated water is inserted into the skeletal framework after long exposure times. Densification into pellets can slow the degradation of MOF-5 significantly, and may present a pathway to enhance the stability of some MOFs.

... If we take seriously Profes-sor Priem's complaint that RBV is flawed be-cause it lacks a theory of consumer utility, then what would the logical corrective measure be? Obviously, the logical solution would be to ex-pand RBV so that it includes a theory of con-sumer utility. ...

... This hypothesis is supported by the synoptic analysis of vegetation, water chemistry, hydrogeology and peat stratigraphy of representative peat ... Initial local and synoptic hydrogeologic surveys in this region showed that spring-fens and some fen water tracks ... 1995; Glaser et al. ...

The discharge rate is critical to the performance of lithium/oxygen batteries: it impacts both cell capacity and discharge-phase morphology, and in so doing may also affect the efficiency of the oxygen-evolution reaction during recharging. First-discharge data from tens of Li/O2 cells discharged across four rates are analyzed statistically to inform these connections. In the practically significant superficial current-density range of 0.1 to 1 mA cm(-2), capacity is found to fall as a power law, with a Peukert's-law exponent of 1.6 ± 0.1. X-ray diffractometry confirms the dominant presence of crystalline Li2O2 in the discharged electrodes. A completely air-free sample-transfer technique was developed to implement scanning electron microscopy (SEM) of the discharge product. SEM imaging of electrodes with near-average capacities provides statistically significant measures of the shape and size variation of electrodeposited Li2O2 particles with respect to discharge current. At lowe...

Ectopic dendrite growth and new synapse formation are known to occur on select kinds of neurons in a wide variety of neuronal storage diseases. As these changes in connectivity occur just proximal to the axonal initial segment, it has been hypothesized that they underlie the generation of abnormal neuronal function in these diseases. We have studied certain aspects of this phenomenon through the use of a plant-derived indolizadine alkaloid, swainsonine, which specifically inhibits the lysosomal hydrolase, alpha-mannosidase. These studies fully document the close morphological similarity between swainsonine-induced and inherited feline alpha-mannosidosis. This includes the presence of clear and floccule-filled storage vacuoles, as seen with routine EM, and axon hillock neurite growth on select cell types, as seen with Golgi staining. The latter was found only on cortical pyramidal neurons and multipolar cells of amygdala, and these same cell types are known to be involved in ectopic ...

Recent studies in northeastern Pennsylvania report higher concentrations of dissolved methane in domestic water wells associated with proximity to nearby gas-producing wells.1,2 We test this possible association by using Chesapeake Energy's baseline dataset of over 11,300 dissolved methane analyses from domestic water wells, densely arrayed in Bradford and nearby counties (Pennsylvania), and near 661 pre-existing oil and gas wells. The majority of these, 92%, were unconventional wells, drilled with horizontal legs and hydraulically fractured. Our dataset is hundreds of times larger than datasets used in prior studies. In contrast to prior findings, we found no statistically significant relationship between dissolved methane concentrations in groundwater from domestic water wells and proximity to pre-existing oil or gas wells. Previous analyses used small sample sets compared to the population of domestic wells available, which may explain the difference in prior findings compared to ours.

The electrochemistry of Mg salts in room-temperature ionic liquids (ILs) was studied using plating/stripping voltammetry to assess the viability of IL solvents for applications in secondary Mg batteries. Borohydride (BH4(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (Tf2N(-)) salts of Mg were investigated. Three ILs were considered: l-n-butyl-3-methylimidazolium (BMIM)-Tf2N, N-methyl-N-propylpiperidinium (PP13)-Tf2N, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium (DEME(+)) tetrafluoroborate (BF4(-)). Salts and ILs were combined to produce binary solutions in which the anions were structurally similar or identical, if possible. Contrary to some prior reports, no salt/IL combination appeared to facilitate reversible Mg plating. In solutions containing BMIM(+), oxidative activity near 0.8 V vs Mg/Mg(2+) is likely associated with the BMIM cation, rather than Mg stripping. The absence of voltammetric signatures of Mg plating from ILs with Tf2N(-) and B...

By employing a combination of three-dimensional atom-probe tomography and first-principles calculations, significant qualitative and quantitative differences in solute segregation at coherent and semicoherent interfaces bounding a single θ' precipitate in an Al-Cu-based alloy are found. Qualitatively, localized segregation is observed at the semicoherent interface, whereas delocalized behavior is present at the coherent facets. Quantitatively, segregation at the semicoherent interface is a factor of 2 greater than at the coherent interface, resulting in a decrease in interfacial energy that is more than 5 times greater than that observed at the coherent facet. These observations illustrate unambiguously the strong couplings among interface structure, chemical composition, and energetics.

Despite their use in a variety of applications, the fundamental properties of metal-ceramic interfaces are still poorly understood. Historically, this has been due to experimental complications associated with the study of a buried interface, and to theoretical difficulties caused by complex interfacial bonding interactions. However, the advent of first-principles techniques based on Density Functional Theory (DFT) has led to new opportunities for highly-accurate computer simulations of the atomic and electronic structure of interfaces. In this study we present a series of DFT calculations on a broad class of Al/ceramic interface systems, with the goal of explaining and predicting the nature of metal-ceramic adhesion. Since the strength of interfacial bonding, as quantified by the ideal work of adhesion Wad , plays a crucial role in determining the mechanical properties of an interface, we have systematically calculated Wad for 20 different interface geometries including oxide (alpha-Al 2O3), carbide (WC, VC), and nitride (VN) ceramic compounds with the goal of identifying trends. In order to identify the optimal atomic structures we consider the effects of several stacking sequences, interface terminations (both polar and non-polar), and allow for full atomic relaxations. For each system we use a variety of methods to carefully analyze the interfacial electronic structure in order to determine the nature of the metal-ceramic bonding. Although we find significant differences in both the interfacial bonding and the inherent electronic structures of the bulk ceramics, our calculations reveal a trend in Wad with respect to the summed surface energies of the interfaced materials (sigmaAl + sigmaceramic). Specifically, we find that surfaces having larger sigma's adhere at interfaces more strongly than those with small sigma's. We argue that this behavior is consistent with the intuitive notion of the surface energy being a measure of surface reactivity, and hence it could be used as a guide in the design of interfacial properties.

: Atomic potentials are useful for molecular dynamics simulations of large systems (millions of atoms). Since the existing potentials for Ta are of limited reliability, we have attempted to develop an improved EAM potential for tantalum using the Force Matching Method. In addition to fitting the potential to the lattice constant, elastic constants, cohesive energy, and vacancy formation energy, we also fit the potential to thousands of forces calculated via DFT for a wide variety of structures including BCC tantalum, beta-tantalum, surfaces, crystal defects, and liquid tantalum. Initial testing of the potential shows that its predictions are in good agreement with experimental values, and are a substantial improvement over previous models.