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Sample records for rock salt structure

  1. Magnetic coupling at perovskite and rock-salt structured interfaces

    SciTech Connect

    Matvejeff, M.; Ahvenniemi, E.; Takahashi, R.; Lippmaa, M.

    2015-10-05

    We study magnetic coupling between hole-doped manganite layers separated by either a perovskite or a rock-salt barrier of variable thickness. Both the type and the quality of the interface have a strong impact on the minimum critical barrier thickness where the manganite layers become magnetically decoupled. A rock-salt barrier layer only 1 unit cell (0.5 nm) thick remains insulating and is able to magnetically de-couple the electrode layers. The technique can therefore be used for developing high-performance planar oxide electronic devices such as magnetic tunnel junctions and quantum well structures that depend on magnetically and electronically sharp heterointerfaces.

  2. Influences of salt structures on reservoir rocks in block L-2, Dutch continental shelf

    SciTech Connect

    Dronkert, H. ); Remmelts, G. )

    1993-09-01

    In the subsurface of the Netherlands Continental Shelf, thick layers of Zechstein salt have developed into salt domes and ridges that pierce through the overlying formations. To measure the range of lateral influence of the salt in these structures on the sandstone reservoir rocks of the Mesozoic sequence, a cementation model was developed. The target area, Block L-2, was chosen for the presence of salt domes, wells, and reservoir rocks. The L-2 case study has been performed on two Triassic sandstone intervals. The lower, Volpriehausen, sandstone showed halite cementation in one well, located within several 100 m from a salt dome. Four other wells, located more than 1.5 km from a salt structure, did not show any signs of halite cementation. Therefore, the lateral influence of salt domes on the surrounding reservoir rock is, in this case, limited to less than 1.5 km at 3-4 km depth. A slightly shallower Triassic sandstone (Detfurth) shows more frequent halite cementation. This cementation can be attributed to early seepage from overlying Rot salt brines.Triassic Rot salt is present above depletion areas of the Zechstein salt structures, and in such a way the seepage can be seen as an indirect influence of the salt structures.

  3. Vacancy structures and melting behavior in rock-salt GeSbTe

    DOE PAGESBeta

    Zhang, Bin; Wang, Xue -Peng; Shen, Zhen -Ju; Li, Xian -Bin; Wang, Chuan -Shou; Chen, Yong -Jin; Li, Ji -Xue; Zhang, Jin -Xing; Zhang, Ze; Zhang, Sheng -Bai; et al

    2016-05-03

    Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological breakthrough in memory devices. Using spherical aberration-aberration corrected scanning transmission electron microscopy and atomic scale energy-dispersive X-ray mapping, we observe a new rock-salt structure with high-degree vacancy ordering (or layered-like ordering) atmore » an elevated temperature, which is a result of phase transition from the rock-salt phase with randomly distributed vacancies. First-principles calculations reveal that the phase transition is an energetically favored process. Furthermore, molecular dynamics studies suggest that the melting of the cubic rock-salt phases is initiated at the vacancies, which propagate to nearby regions. The observation of multi-rock-salt phases suggests another route for multi-level data storage using GeSbTe.« less

  4. Vacancy Structures and Melting Behavior in Rock-Salt GeSbTe.

    PubMed

    Zhang, Bin; Wang, Xue-Peng; Shen, Zhen-Ju; Li, Xian-Bin; Wang, Chuan-Shou; Chen, Yong-Jin; Li, Ji-Xue; Zhang, Jin-Xing; Zhang, Ze; Zhang, Sheng-Bai; Han, Xiao-Dong

    2016-01-01

    Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological breakthrough in memory devices. Using spherical aberration-aberration corrected scanning transmission electron microscopy and atomic scale energy-dispersive X-ray mapping, we observe a new rock-salt structure with high-degree vacancy ordering (or layered-like ordering) at an elevated temperature, which is a result of phase transition from the rock-salt phase with randomly distributed vacancies. First-principles calculations reveal that the phase transition is an energetically favored process. Moreover, molecular dynamics studies suggest that the melting of the cubic rock-salt phases is initiated at the vacancies, which propagate to nearby regions. The observation of multi-rock-salt phases suggests another route for multi-level data storage using GeSbTe. PMID:27140674

  5. Vacancy Structures and Melting Behavior in Rock-Salt GeSbTe

    PubMed Central

    Zhang, Bin; Wang, Xue-Peng; Shen, Zhen-Ju; Li, Xian-Bin; Wang, Chuan-Shou; Chen, Yong-Jin; Li, Ji-Xue; Zhang, Jin-Xing; Zhang, Ze; Zhang, Sheng-Bai; Han, Xiao-Dong

    2016-01-01

    Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological breakthrough in memory devices. Using spherical aberration-aberration corrected scanning transmission electron microscopy and atomic scale energy-dispersive X-ray mapping, we observe a new rock-salt structure with high-degree vacancy ordering (or layered-like ordering) at an elevated temperature, which is a result of phase transition from the rock-salt phase with randomly distributed vacancies. First-principles calculations reveal that the phase transition is an energetically favored process. Moreover, molecular dynamics studies suggest that the melting of the cubic rock-salt phases is initiated at the vacancies, which propagate to nearby regions. The observation of multi-rock-salt phases suggests another route for multi-level data storage using GeSbTe. PMID:27140674

  6. Vacancy Structures and Melting Behavior in Rock-Salt GeSbTe

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Wang, Xue-Peng; Shen, Zhen-Ju; Li, Xian-Bin; Wang, Chuan-Shou; Chen, Yong-Jin; Li, Ji-Xue; Zhang, Jin-Xing; Zhang, Ze; Zhang, Sheng-Bai; Han, Xiao-Dong

    2016-05-01

    Ge-Sb-Te alloys have been widely used in optical/electrical memory storage. Because of the extremely fast crystalline-amorphous transition, they are also expected to play a vital role in next generation nonvolatile microelectronic memory devices. However, the distribution and structural properties of vacancies have been one of the key issues in determining the speed of melting (or amorphization), phase-stability, and heat-dissipation of rock-salt GeSbTe, which is crucial for its technological breakthrough in memory devices. Using spherical aberration-aberration corrected scanning transmission electron microscopy and atomic scale energy-dispersive X-ray mapping, we observe a new rock-salt structure with high-degree vacancy ordering (or layered-like ordering) at an elevated temperature, which is a result of phase transition from the rock-salt phase with randomly distributed vacancies. First-principles calculations reveal that the phase transition is an energetically favored process. Moreover, molecular dynamics studies suggest that the melting of the cubic rock-salt phases is initiated at the vacancies, which propagate to nearby regions. The observation of multi-rock-salt phases suggests another route for multi-level data storage using GeSbTe.

  7. Bonding preference of carbon, nitrogen, and oxygen in niobium-based rock-salt structures.

    PubMed

    Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro; Wada, Satoshi; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2013-09-01

    Carbon, nitrogen, and oxygen are essential components in solid-state materials. However, understanding their preference on the bonding to metals has not been straightforward. Here, niobium carbide, nitride, and oxide with simple rock-salt-based structures were analyzed by first-principles calculations and synchrotron X-ray diffraction. We found that an increase in the atomic number from carbon to oxygen formed fewer and shorter bonds to metals with better hybridization of atomic orbitals. This can provide a simple guiding principle for understanding the bonding and designing carbides, nitrides, oxides, and mixed-anion compounds. PMID:23937352

  8. High temperature thermoelectric properties of rock-salt structure PbS

    DOE PAGESBeta

    Parker, David S.; Singh, David J.

    2013-12-18

    We present an analysis of the high temperature transport properties of rock-salt structure PbS, a sister compound to the better studied lead chalcogenides PbSe and PbTe. In this study, we find thermopower magnitudes exceeding 200 V/K in a wide doping range for temperatures of 800 K and above. Based on these calculations, and an analysis of recent experimental work we find that this material has a potential for high thermoelectric performance. Also, we find favorable mechanical properties, based on an analysis of published data.

  9. The application of high resolution X-ray computed tomography on naturally deformed rock salt: Multi-scale investigations of the structural inventory

    NASA Astrophysics Data System (ADS)

    Thiemeyer, Nicolas; Habersetzer, Jörg; Peinl, Mark; Zulauf, Gernold; Hammer, Jörg

    2015-08-01

    X-ray computed tomography (CT) represents a useful technique providing new perspectives and insights for the structural investigation of naturally-deformed rock salt. Several samples of Permian rock salt from Gorleben, Asse and Teutschenthal (Germany) were investigated by exploiting the non-destructive nature of μCT and nCT techniques particularly for salt rocks. CT imaging enabled the visualization and quantification of anhydrite impurities, pore space and fluid phases located along grain-boundaries or trapped as intracrystalline inclusions. Disseminated grains and aggregates of anhydrite in rock salt of the Gorleben salt dome have been visualized and quantified by μCT for the first time in order to portray their spatial occurrence. The visualization of anhydrite aggregates and pore space shows no correlation between their spatial distributions. This independence excludes the anhydrite to be responsible for elevated porosity (0.87 ± 0.07 vol.-%). High-resolution nCT scans (≤1 μm voxel size) of single intracrystalline and grain-boundary fluid inclusions from Gorleben and Asse rock salt allowed the visualization and quantification of their various phase components. A major achievement is the detailed description of the morphology and shape of the fluid inclusions and of their phase components, which has not been conducted in rock salt research by high-resolution X-ray CT imaging before.

  10. Zinc-blende to rock-salt structural phase transition of BP and BAs under high pressure

    NASA Astrophysics Data System (ADS)

    Sarwan, Madhu; Bhardwaj, Purvee; Singh, Sadhna

    2013-11-01

    In the present paper, we have investigated the pressure induced phase transition and thermophysical properties of BP and BAs by means of modified interaction potential model (MIPM). The MIPM consists of Coulomb interaction, three-body interaction (TBI) modified by taking covalency effect, van-der Waal interaction (vdW), short range overlap repulsive interaction and zero point energy effect. These compounds crystallize in zinc-blende (ZB) structure at ambient condition and transform to rock-salt (RS) structure at pressures 111 and 93 GPa and their equation of state show volume collapse of 14% and 4% respectively for BP and BAs. The second order elastic constants have also been computed at zero and high pressures. Our results are in good agreement with the experimental results. The mechanical and thermophysical properties in ZB structure are also predicted.

  11. Se EXAFS study of the elevated wurtzite to rock salt structural phase transition in CdSe nanocrystals

    SciTech Connect

    Tolbert, S.H.; Alivisatos, A.P. |

    1993-09-01

    High pressure Se EXAFS data has been obtained on 2.7 nm radius CdSe semiconductor nanocrystals. This system is observed to undergo a solid-solid phase transition at 6.5 GPa which is approximately twice the reported value for bulk CdSe. In combination with high pressure optical absorption experiments, EXAFS data can be used to identify the high-pressure phase structure as rock salt. EXAFS data can be fit with equations of state to yield pressure volume curves. Resultant values of bulk modulus and its derivative with respect to pressure are B{sub o} = 37 {plus_minus} 5 GPa and B{sub o}{prime} = 11 {plus_minus} 3. A thermodynamic model for the data is presented in which the internal energy in each phase is modified by a surface energy term. Differences in surface energy are used to explain the elevation in phase transition pressure. The model can be used to estimate a value for the surface energy in the rock salt phase; 1.9 {plus_minus} 0.3 N/m is obtained in comparison to 0.9 {plus_minus} 0. 1 N/m for the wurtzite phase.

  12. Structural and electronic properties of TiX (X=N, As) in rock salt and zinc blende phase: A DFT study

    NASA Astrophysics Data System (ADS)

    Verma, U. P.; Nayak, V.

    2016-05-01

    Quantum mechanical first principle calculations have been performed to study the electronic and structural properties of TiN and TiAs in zinc blende (ZB) and rock salt (RS) structures. The full-potential linearized augmented plane wave (FP-LAPW) method has been used within the framework of density functional theory (DFT). The exchange correlation functional has been solved employing generalized gradient approximation (GGA). Our predicted results for lattice constants are in good agreement with the earlier findings. The electronic band structures of TiX are metallic in both the phases.

  13. Fracture and Healing of Rock Salt Related to Salt Caverns

    SciTech Connect

    Chan, K.S.; Fossum, A.F.; Munson, D.E.

    1999-03-01

    In recent years, serious investigations of potential extension of the useful life of older caverns or of the use of abandoned caverns for waste disposal have been of interest to the technical community. All of the potential applications depend upon understanding the reamer in which older caverns and sealing systems can fail. Such an understanding will require a more detailed knowledge of the fracture of salt than has been necessary to date. Fortunately, the knowledge of the fracture and healing of salt has made significant advances in the last decade, and is in a position to yield meaningful insights to older cavern behavior. In particular, micromechanical mechanisms of fracture and the concept of a fracture mechanism map have been essential guides, as has the utilization of continuum damage mechanics. The Multimechanism Deformation Coupled Fracture (MDCF) model, which is summarized extensively in this work was developed specifically to treat both the creep and fracture of salt, and was later extended to incorporate the fracture healing process known to occur in rock salt. Fracture in salt is based on the formation and evolution of microfractures, which may take the form of wing tip cracks, either in the body or the boundary of the grain. This type of crack deforms under shear to produce a strain, and furthermore, the opening of the wing cracks produce volume strain or dilatancy. In the presence of a confining pressure, microcrack formation may be suppressed, as is often the case for triaxial compression tests or natural underground stress situations. However, if the confining pressure is insufficient to suppress fracture, then the fractures will evolve with time to give the characteristic tertiary creep response. Two first order kinetics processes, closure of cracks and healing of cracks, control the healing process. Significantly, volume strain produced by microfractures may lead to changes in the permeability of the salt, which can become a major concern in

  14. Rock-salt structure lithium deuteride formation in liquid lithium with high-concentrations of deuterium: a first-principles molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Chen, Mohan; Abrams, T.; Jaworski, M. A.; Carter, Emily A.

    2016-01-01

    Because of lithium’s possible use as a first wall material in a fusion reactor, a fundamental understanding of the interactions between liquid lithium (Li) and deuterium (D) is important. We predict structural and dynamical properties of liquid Li samples with high concentrations of D, as derived from first-principles molecular dynamics simulations. Liquid Li samples with four concentrations of inserted D atoms (LiDβ , β =0.25 , 0.50, 0.75, and 1.00) are studied at temperatures ranging from 470 to 1143 K. Densities, diffusivities, pair distribution functions, bond angle distribution functions, geometries, and charge transfer between Li and D atoms are calculated and analyzed. The analysis suggests liquid-solid phase transitions can occur at some concentrations and temperatures, forming rock-salt LiD within liquid Li. We also observe formation of some D2 molecules at high D concentrations.

  15. New rock salt-related oxides Li{sub 3}M{sub 2}RuO{sub 6} (M=Co, Ni): Synthesis, structure, magnetism and electrochemistry

    SciTech Connect

    Laha, S.; Morán, E.; Sáez-Puche, R.; Alario-Franco, M.Á.; Dos santos-Garcia, A.J.; Gonzalo, E.; Kuhn, A.; García-Alvarado, F.; Sivakumar, T.; Tamilarasan, S.; Natarajan, S.; Gopalakrishnan, J.

    2013-07-15

    We describe the synthesis, crystal structure, magnetic and electrochemical characterization of new rock salt-related oxides of formula, Li{sub 3}M{sub 2}RuO{sub 6} (M=Co, Ni). The M=Co oxide adopts the LiCoO{sub 2} (R-3m) structure, where sheets of LiO{sub 6} and (Co{sub 2}/Ru)O{sub 6} octahedra are alternately stacked along the c-direction. The M=Ni oxide also adopts a similar layered structure related to Li{sub 2}TiO{sub 3}, where partial mixing of Li and Ni/Ru atoms lowers the symmetry to monoclinic (C2/c). Magnetic susceptibility measurements reveal that in Li{sub 3}Co{sub 2}RuO{sub 6}, the oxidation states of transition metal ions are Co{sup 3+} (S=0), Co{sup 2+} (S=1/2) and Ru{sup 4+} (S=1), all of them in low-spin configuration and at 10 K, the material orders antiferromagnetically. Analogous Li{sub 3}Ni{sub 2}RuO{sub 6} presents a ferrimagnetic behavior with a Curie temperature of 100 K. The differences in the magnetic behavior have been explained in terms of differences in the crystal structure. Electrochemical studies correlate well with both magnetic properties and crystal structure. Li-transition metal intermixing may be at the origin of the more impeded oxidation of Li{sub 3}Ni{sub 2}RuO{sub 6} when compared to Li{sub 3}Co{sub 2}RuO{sub 6}. Interestingly high first charge capacities (between ca. 160 and 180 mAh g{sup −1}) corresponding to ca. 2/3 of theoretical capacity are reached albeit, in both cases, capacity retention and cyclability are not satisfactory enough to consider these materials as alternatives to LiCoO{sub 2}. - Graphical abstract: Two new rock salt related oxides of formula, Li{sub 3}M{sub 2}RuO{sub 6}, (M=Co, Ni) have been prepared. The M=Co oxide adopts the LiCoO{sub 2} (R-3m) structure and the M=Ni oxide adopts a similar layered structure related to Li{sub 2}TiO{sub 3,} monoclinic (C2/c), with partial mixing of Li and Ni/Ru atoms. For Li{sub 3}Co{sub 2}RuO{sub 6}, oxidation state for Ru is 4+ and antiferromagnetic (AFM) order is

  16. Excavation Damaged Zones In Rock Salt Formations

    SciTech Connect

    Jockwer, N.; Wieczorek, K.

    2008-07-01

    Salt formations have long been proposed as potential host rocks for nuclear waste disposal. After the operational phase of a repository the openings, e.g., boreholes, galleries, and chambers, have to be sealed in order to avoid the release of radionuclides into the biosphere. For optimising the sealing techniques knowledge about the excavation damaged zones (EDZ) around these openings is essential. In the frame of a project performed between 2004 and 2007, investigations of the EDZ evolution were performed in the Stassfurt halite of the Asse salt mine in northern Germany. Three test locations were prepared in the floor of an almost 20 year old gallery on the 800-m level of the Asse mine: (1) the drift floor as existing, (2) the new drift floor shortly after removing of a layer of about 1 m thickness of the floor with a continuous miner, (3) the new drift floor 2 years after cutting off the 1-m layer. Subject of investigation were the diffusive and advective gas transport and the advective brine transport very close to the opening. Spreading of the brine was tracked by geo-electric monitoring in order to gain information about permeability anisotropy. Results obtained showed that EDZ cut-off is a useful method to improve sealing effectiveness when constructing technical barriers. (authors)

  17. Rheological stratification of the Hormuz Salt Formation in Iran - microstructural study of the dirty and pure rock salts from the Kuh-e-Namak (Dashti) salt diapir

    NASA Astrophysics Data System (ADS)

    Závada, Prokop; Desbois, Guillaume; Urai, Janos; Schulmann, Karel; Rahmati, Mahmoud; Lexa, Ondrej; Wollenberg, Uwe

    2014-05-01

    Significant viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between 'weak' terrestrial debris bearing rock salt types and 'strong' pure rock salt types are questioned for deformation mechanisms using detailed quantitative microstructural study including crystallographic preferred orientation (CPO) mapping of halite grains. While the solid impurity rich ("dirty") rock salts contain disaggregated siltstone and dolomite interlayers, "clean" salts (debris free) reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although flow in both, the recrystallized dirty and clean salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS) and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts are explained by significantly slower rates of intergranular diffusion and piling up of dislocations at hematite inclusions in clean salt types. Porphyroclasts of clean salts deform by semi-brittle and plastic mechanisms with intra-crystalline damage being induced also by fluid inclusions that explode in the crystals at high fluid pressures. Boudins of clean salt types with coarse grained and original sedimentary microstructure suggest that clean rock salts are associated with dislocation creep dominated power law flow in the source layer and the diapiric stem. Rheological contrasts between both rock salt classes apply in general for the variegated and terrestrial debris rich ("dirty") Lower Hormuz and the "clean" rock salt forming the Upper Hormuz, respectively, and suggest that large strain rate gradients likely exist along horizons of mobilized salt types of different composition and microstructure.

  18. Deformation-assisted fluid percolation in rock salt.

    PubMed

    Ghanbarzadeh, Soheil; Hesse, Marc A; Prodanović, Maša; Gardner, James E

    2015-11-27

    Deep geological storage sites for nuclear waste are commonly located in rock salt to ensure hydrological isolation from groundwater. The low permeability of static rock salt is due to a percolation threshold. However, deformation may be able to overcome this threshold and allow fluid flow. We confirm the percolation threshold in static experiments on synthetic salt samples with x-ray microtomography. We then analyze wells penetrating salt deposits in the Gulf of Mexico. The observed hydrocarbon distributions in rock salt require that percolation occurred at porosities considerably below the static threshold due to deformation-assisted percolation. Therefore, the design of nuclear waste repositories in salt should guard against deformation-driven fluid percolation. In general, static percolation thresholds may not always limit fluid flow in deforming environments. PMID:26612949

  19. Thermal expansion of rock-salt cubic AlN

    NASA Astrophysics Data System (ADS)

    Bartosik, M.; Todt, M.; Holec, D.; Todt, J.; Zhou, L.; Riedl, H.; Böhm, H. J.; Rammerstorfer, F. G.; Mayrhofer, P. H.

    2015-08-01

    We combine continuum mechanics modeling and wafer curvature experiments to characterize the thermal expansion coefficient of AlN in its metastable cubic rock-salt (B1) structure. The latter was stabilized as nm thin layers by coherency strains in CrN/AlN epitaxial multilayers deposited on Si (100) substrates using reactive magnetron sputtering. The extraction of the B1-AlN thermal expansion coefficient, from experimentally recorded temperature dependent wafer curvature data, is formulated as an inverse problem using continuum mechanics modeling. The results are cross-validated by density functional theory calculations.

  20. Changes in rock salt permeability due to nearby excavation

    SciTech Connect

    Stormont, J C; Howard, C L

    1991-07-01

    Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.

  1. Microbial biodiversity in Alpine Permo-Triassic rock salt

    NASA Astrophysics Data System (ADS)

    Radax, C.; Wieland, H.; Pfaffenhuemer, M.; Leuko, S.; Rittmann, S.; Weidler, G.; Gruber, C.; Stan-Lotter, H.

    2003-04-01

    Alpine Permo-Triassic rock salt (age 200-250 million years) was shown several times to contain living extremely halophilic Archaea. These organisms might stem from ancient populations that became entrapped and persisted in the rock salt since then. For this reason, rock salt is considered a promising model system for the search for bacterial extraterrestrial life. In our studies on biodiversity in Alpine rock salt, we employed both culture-dependent and culture-independent, PCR-based methods. The latter approach indicated the presence of at least 12 distinct sequence types (phylotypes) in our samples, all of which belonged to the extremely halophilic Archaea. None of the recovered sequences was identical to sequences from databases, suggesting the avoidance of contaminants during experimental procedures. Two phylotypes could be assigned to taxonomically described members of this family; the remaining ten phylotypes appeared only remotely related to known genera of the extremely halophilic Archaea. In contrast, attempts to isolate organisms from the same sample on 15 different growth media so far yielded only two groups of isolates that could be differentiated based on their 16S rRNA genes. One group was very similar to Halococcus strains that we frequently isolated from Alpine rock salt; the other group was closely correlated to one of our novel phylotypes. Analyses of whole cell protein patterns allowed to further differentiate the latter group into two different subgroups that could not be distinguished at the molecular level. These results show that both culture-dependent and culture-independent strategies have to be applied in order to obtain a more complete view of microbial biodiversity in Permo-Triassic rock salt: culture-independent methods yield information on the gross microbial diversity in rock salt, whereas subtle differences can currently only be registered between cultivated strains.

  2. Textural evidence for origin of salt dome anhydrite cap rocks, Winnfield Dome, Louisiana

    SciTech Connect

    Ulrich, M.R.; Kyle, J.R.; Price, P.E.

    1985-02-01

    Textures within anhydrite cap rock are products of repeated cycles of halie dissolution and residual anhydrite accretion at tops of salt stocks. Quarrying operations at Winnfield dome have exposed extensive portions of the anhydrite cap rock zone. This zone is composed primarily of unoriented, xenoblastic anhydrite crystals in laminae less than 1 mm to several centimeters thick. Laminations are defined by thin, dark sulfide accumulations and pressure solution of anhydrite. Deformed, banded anhydrite clasts are contained locally within laminae. Multiple-laminated, concave downward anhydrite mounds occur along some horizons. They may contain anhydrite breccia fragments or sulfides. Coarsely crystalline salt mounds, containing disseminated idioblastic anhydrite also occur along horizons. Mound morphologies vary from tall and thin to broad and squat; maximum dimensions range from less than 0.5 to about 2.0 m. These moundlike structures are related spatially and genetically. Moundlike structures are believed to form from salt spines along the salt-anhydrite contact. As the spine dissolves through several cycles of dissolution and accretion, a laminated anhydrite mound is preserved; if the spine becomes isolated from dissolution, then a salt inclusion is preserved. Anhydrite beds within the Louann Salt, deformed during diapirism, are preserved as deformed anhydrite clasts. Steeply dipping, bedded anhydrite zones within the salt stock may produce brecciated anhydrite mounds when incorporated into the cap rock. Sulfides record the movement of metalliferous fluids through the salt-anhydrite contact.

  3. Damage-induced nonassociated inelastic flow in rock salt

    SciTech Connect

    Chan, K.S.; Bodner, S.R.; Brodsky, N.S.; Fossum, A.F.

    1993-06-01

    The multi-mechanism deformation coupled fracture model recently developed by CHAN, et al. (1992), for describing time-dependent, pressure-sensitive inelastic flow and damage evolution in crystalline solids was evaluated against triaxial creep experiments on rock salt. Guided by experimental observations, the kinetic equation and the flow law for damage-induced inelastic flow in the model were modified to account for the development of damage and inelastic dilatation in the transient creep regime. The revised model was then utilized to obtain the creep response and damage evolution in rock salt as a function of confining pressure and stress difference. Comparison between model calculation and experiment revealed that damage-induced inelastic flow is nonassociated, dilatational, and contributes significantly to the macroscopic strain rate observed in rock salt deformed at low confining pressures. The inelastic strain rate and volumetric strain due to damage decrease with increasing confining pressures, and all are suppressed at sufficiently high confining pressures.

  4. Interactive evolution concept for analyzing a rock salt cavern under cyclic thermo-mechanical loading

    NASA Astrophysics Data System (ADS)

    König, Diethard; Mahmoudi, Elham; Khaledi, Kavan; von Blumenthal, Achim; Schanz, Tom

    2016-04-01

    The excess electricity produced by renewable energy sources available during off-peak periods of consumption can be used e.g. to produce and compress hydrogen or to compress air. Afterwards the pressurized gas is stored in the rock salt cavities. During this process, thermo-mechanical cyclic loading is applied to the rock salt surrounding the cavern. Compared to the operation of conventional storage caverns in rock salt the frequencies of filling and discharging cycles and therefore the thermo-mechanical loading cycles are much higher, e.g. daily or weekly compared to seasonally or yearly. The stress strain behavior of rock salt as well as the deformation behavior and the stability of caverns in rock salt under such loading conditions are unknown. To overcome this, existing experimental studies have to be supplemented by exploring the behavior of rock salt under combined thermo-mechanical cyclic loading. Existing constitutive relations have to be extended to cover degradation of rock salt under thermo-mechanical cyclic loading. At least the complex system of a cavern in rock salt under these loading conditions has to be analyzed by numerical modeling taking into account the uncertainties due to limited access in large depth to investigate material composition and properties. An interactive evolution concept is presented to link the different components of such a study - experimental modeling, constitutive modeling and numerical modeling. A triaxial experimental setup is designed to characterize the cyclic thermo-mechanical behavior of rock salt. The imposed boundary conditions in the experimental setup are assumed to be similar to the stress state obtained from a full-scale numerical simulation. The computational model relies primarily on the governing constitutive model for predicting the behavior of rock salt cavity. Hence, a sophisticated elasto-viscoplastic creep constitutive model is developed to take into account the dilatancy and damage progress, as well as

  5. Creep healing of fractures in rock salt

    SciTech Connect

    Costin, L. S.; Wawersik, W. R.

    1980-08-01

    Fracture and healing experiments were performed on specimens of bedded salt from the Salado formation, southeastern New Mexico. Short rod specimens (100 mm in diameter) were loaded to failure in tension. During each test, a crack was initiated along the axis of the specimen. The fracture toughness of the salt was determined from the resulting load-crack opening displacement record. After the test, each specimen was pieced back together, jacketed and placed in a pressure vessel under hydrostatic pressure for several days. The confining pressure (10 to 35 MPa), temperature (22 to 100/sup 0/C) and healing time (4 to 8 days) were varied to determine the effect of each on the healing process. Upon removal from the pressure vessel, each sample was retested and the toughness of the healed fracture was determined. Results show that the salt specimens regained 70 to 80% of their original strength under all conditions except at the lowest temperature and pressure where specimens regained only 20 to 30% of their original strength. It is suspected that the primary mechanism involved is creep of asperities along the fracture surface which forms an interlocking network. Thus, the healing pressure is probably the most significant variable.

  6. Impact of solid second phases on deformation mechanisms of naturally deformed salt rocks (Kuh-e-Namak, Dashti, Iran) and rheological stratification of the Hormuz Salt Formation

    NASA Astrophysics Data System (ADS)

    Závada, P.; Desbois, G.; Urai, J. L.; Schulmann, K.; Rahmati, M.; Lexa, O.; Wollenberg, U.

    2015-05-01

    Viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between 'weak' second phase bearing rock salt and 'strong' pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study. While the solid inclusions rich ("dirty") rock salts contain disaggregated siltstone and dolomite interlayers, "clean" salts reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although the flow in both, the recrystallized "dirty" and "clean" salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS), transgranular microcracking and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts observed in the field outcrops are explained by: 1) enhanced ductility of "dirty" salts due to increased diffusion rates along the solid inclusion-halite contacts than along halite-halite contacts, and 2) slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for "clean" salt types Rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the "dirty" salt forming Lower Hormuz and the "clean" salt forming the Upper Hormuz of the Hormuz Formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure.

  7. Evidence for episodic basin dewatering in salt-dome cap rocks

    SciTech Connect

    Hallager, W.S. ); Ulrich, M.R. ); Kyle, J.R.; Gose, W.A. ); Price, P.E. )

    1990-08-01

    A detailed record of episodic basin-dewatering events is preserved in the anhydrite cap rocks to two Gulf Coast salt domes. Metal rich brines were intermittently expelled geopressured zones deep in the stratigraphic section and were channeled upward along escape structures bounding the salt diapirs. Overhanging anhydrite cap rock helped to focus some escaping fluid into the zone of dissolution between the top of salt and overlying residual anhydrite cap rock. Iron, lead, and zinc sulfide solubilities were exceeded in this zone, possibly in response to dissolution and reduction of cap-rock sulfates. Because the metalliferous brines entered the dissolution zone intermittently, they were recorded as relatively thin horizontal bands of sulfide sandwiched between thicker accumulations of anhydrite. Continued dissolution of salt and underplating of residual anhydrite caused the sulfide bands to be displaced upward relative to the base of the cap, leading to an inverted stratigraphic record of basin-dewatering events. Paleomagnetic data from the Winnfield salt dome suggest the sulfide-producing basin-dewatering events and anhydrite cap-rock accumulation occurred between 157 and 145 Ma.

  8. Astrobiology with haloarchaea from Permo-Triassic rock salt

    NASA Astrophysics Data System (ADS)

    Stan-Lotter, H.; Radax, C.; Gruber, C.; Legat, A.; Pfaffenhuemer, M.; Wieland, H.; Leuko, S.; Weidler, G.; Kömle, N.; Kargl, G.

    2002-10-01

    Several viable halophilic archaebacteria were isolated previously from rock salt of Permo-Triassic age in an Austrian salt mine; one of these strains was the first to be recognized as a novel species from subterranean halite and was designated Halococcus salifodinae. The halophilic microorganisms have apparently survived in the salt sediments over extremely long periods of time. Halobacteria could therefore be suitable model organisms for exploring the possibility of long-term survival of microbes on other planets, in particular, since extraterrestrial halite has been detected in meteorites and is assumed to be present in the subsurface ocean on Europa. Our efforts are directed at the identification of the microbial content of ancient rock salt and the development of procedures for the investigation of the halobacterial response to extreme environmental conditions. Using modified culture media, further halophilic strains were isolated from freshly blasted rock salt and bore cores; in addition, growth of several haloarchaea was substantially improved. Molecular methods indicated the presence of at least 12 different 16S rRNA gene species in a sample of Alpine rock salt, but these strains have not been cultured yet. The exploration of Mars is a target of space missions in the 21st century; therefore, testing the survival of haloarchaea under conditions comparable to present-day Mars, using a simulation chamber, was begun. Preliminary results with Halococcus and Halobacterium species suggested at least tenfold higher survival rates when cells were kept in liquid brines than under dry conditions; staining of cells with the LIVE DEAD kit, which discriminates between damaged and intact membranes, corroborated these data.

  9. The effect of hydrocarbons on the microstructural evolution in rock salt: a case study on hydrocarbon bearing Ara salt from the South Oman Salt Basin

    NASA Astrophysics Data System (ADS)

    Schmatz, Joyce; Urai, Janos L.; Wübbeler, Franziska M. M.; Sadler, Marc

    2014-05-01

    It has been shown that dilatant deformation promotes the incorporation of hydrocarbons into typically low permeable rock salt (Schoenherr et al., 2007). However, there is not much knowledge on subsequent mechanisms related to recrystallization processes, which cause morphological and chemical changes of the carbonic inclusions. This work aims to contribute to an increased understanding of fluid inclusion dynamics related to grain boundary migration recrystallization and hence to facilitate the interpretation of complex microstructures in recrystallized, multiphase salt rocks. In this case study we investigate hydrocarbon-impregnated salt from the Cambrian Ara Group in the South Oman Salt Basin. The samples were cored from cm-m thick anhydrite-salt sequences overlying hydrocarbon bearing carbonate stringers in 3300 m depth. The anhydrite layers consist mainly of fine-grained anhydrite, which contains calcite, dolomite, and olivine inclusions. Solid bitumen and lighter hydrocarbon phases are observed in between the anhydrite grains and along cracks. Anhydrite layers host salt veins, which contain fragments of anhydrite. These fragments do not differ in composition or structure from the host material and the related vein microstructures indicate crack-seal mechanisms. Halite in the salt layers is almost entirely recrystallized with solid inclusions consisting of anhydrite, calcite, dolomite and olivine with hydrocarbon-coatings present inside grains and along grain boundaries. Solid inclusions cause pinning indicated by a decreased recrystallized grain size and by the presence of grains with preserved substructures representing earlier deformation phases. We observe two types of carbonic inclusions: I) solid bitumen coatings along grain boundaries and microcracks, interpreted to be incorporated into the salt in an overpressure state that allowed dilatancy of the salt, and II) less degraded, liquid hydrocarbons along grain boundaries in the vicinity of the anhydrite

  10. Numerical simulation of salt cementation in the porous rocks adjacent to salt diapirs

    NASA Astrophysics Data System (ADS)

    Allstadt, Raphael; Li, Shiyuan; Marquart, Gabriele; Reuning, Lars; Niederau, Jan

    2015-04-01

    Porosity and permeability are among the most important petrophysical properties of reservoirs rocks in oil systems. Observations during exploration indicate that in the vicinity of salt domes the porosity of reservoir rocks is often reduced by halite cementation. In this study we present results of simulating the process of salt precipitation near salt diapirs by using a schematic model of a Zechstein diapir in the North Sea basin. The numerical simulation is based on solving the transport equations for heat, porous flow and dispersive and reactive chemical species. Chemical reaction and equilibrium is based on the PHREEQC computer code. In our model over-pressured brine is entering from below and is deflected towards the diapir due to an intermediate layer of low permeability. The high thermal conductivity of salt yields a lateral temperature gradient starting from the diapir. Due to this effect the simulated temperature profile shows lower temperatures close to the salt dome than in comparable depths further away. Caused by the temperature-controlled solubility of NaCl in the brine and supplied ions by the diapir, halite first precipitates near the salt diapir by cementing the pore spaces and thus reducing the porosity. Salt-precipitation in the simulation starts after 840 000 years and reduces the porosity from 10 % to 5.5 % after 19 Mill. years. The permanent influx of brine causes growth of the cementation area and the related reduction of porosity in the reservoir.

  11. Salt Attack on Rocks and Expansion of Soils on Mars

    NASA Astrophysics Data System (ADS)

    Vaniman, D. T.; Bish, D. L.; Chipera, S. J.; Carey, J. W.

    2004-12-01

    Salt-rich sediments observed by the MER rover Opportunity at Meridiani Planum show that brines have been present on Mars in the past, but a role for groundwater in widespread rock weathering and soil formation is uncertain. Experiments by several groups suggest instead the action of acid fog over long time spans, with episodic input of volcanic gases, as a more significant agent of Mars weathering. Salt minerals formed in these acid weathering experiments consistently include gypsum and alunogen, with epsomite or hexahydrite forming where olivine provides a source of Mg. Analogous to the martian acid fog scenario are terrestrial acid rain or acid fog attacks on building and monument stone by chemical action and mechanical wedging through growth of gypsum, anhydrite, epsomite, hexahydrite, kieserite, and other sulfate minerals. Physical effects can be aggressive, operating by both primary salt growth and hydration of anhydrous or less-hydrous primary salts. In contrast, soils evolve to states where chemical attack is lessened and salt mineral growth leads to expansion with cementation; in this situation the process becomes constructive rather than destructive. We have made synthetic salt-cemented soils (duricrusts) from clays, zeolites, palagonites and other media mixed with ultrapure Mg-sulfate solutions. Although near-neutral in pH, these solutions still exchange or leach Ca from the solids to form cements containing gypsum as well as hexahydrite. At low total P (1 torr) and low RH (<1%) hexahydrite becomes amorphous but gypsum does not. If allowed to rehydrate from vapor at higher RH, the Mg-sulfate component of the duricrust expands by formation of a complex mixture of Mg-sulfate phases with various hydration states. The expanded form is retained even if the duricrust is again dehydrated, suggesting that soil porosity thus formed is difficult to destroy. These processes can be considered in the context of Viking, Pathfinder, and MER evidence for differing salt

  12. Deformation of underground deep cavities in rock salts at their long-term operations

    SciTech Connect

    Zhuravleva, T.; Shafarenko, E.

    1995-12-01

    The underground deep cavities are created in rock salts of various morphological types with the purpose of storage of petroleum, gas and nuclear wastes. It is well known that the rock salt has rheological properties, which can result in closure of caverns and loss of their stability. In the evaporitic rocks, especially those containing halite, time-dependent deformation is pronounced even at comparatively low stress levels. At high stress levels this creep becomes a dominant feature of the mechanical behavior of salt rocks. So the knowledge of creep behavior of rock salt is of paramount importance in underground storage application of gas, petroleum products and nuclear wastes.

  13. Rock bolt certification tests in salt, Eddy County, New Mexico

    SciTech Connect

    Stewart, R.M.

    1981-11-01

    One hundred rock bolts were installed and tested in the Kerr-McGee potash mine near Carlsbad, New Mexico. The bolts were installed in salt, then instrumented and loaded to failure. The failure modes for tensile tests were expansion shell slippage in salt or polyester resin slippage in salt. The failure modes for shear tests were a combination of bending and shearing or breaking of the bolts near the shear plate-salt interface. Safety factors are not included in the bolt loads in the report. Grade 75 (75,000 psi yield strength) rock bolts with 5/8- and 3/4-in. diameters were stressed into the yield region during tensile and shear tests with 1-3/8-in.-diam by 3-in. expansion shells. The theoretical yield load was 17,000 lb for 5/8-in. bolts and 25,000 lb for 3/4-in. bolts. One-inch-diameter bolts could not be adequately anchored with a single expansion shell to provide yielding. The average anchorage for all bolts moved 1.38 in. before reaching a maximum load of 27,000 lb. Grade 60 (60,000 psi yield strength) deformed reinforcing bar bolts, 1-in. diameter were stressed into the computed yield region approximately 47,000 lb during tensile tests. Yielding was accomplished with polyester resin anchorage when 2 or more resin cartridges (1-1/4 in. by 12 in.) were used. In shear tests, Grade 60 threaded rebar bolts, 1-in. diam, anchored with polyester resin, bent and broke at an average shear force of 34,200 lb with a displacement of 0.52 in.

  14. Geohydromechanical Processes in the Excavation Damaged Zone in Crystalline Rock, Rock Salt, and Indurated and Plastic Clays

    SciTech Connect

    Tsang, Chin-Fu; Bernier, Frederic; Davies, Christophe

    2004-06-20

    The creation of an excavation disturbed zone or excavation damaged zone is expected around all man-made openings in geologic formations. Macro- and micro-fracturing, and in general a redistribution of in situ stresses and rearrangement of rock structures, will occur in this zone, resulting in drastic changes of permeability to flow, mainly through the fractures and cracks induced by excavation. Such an EDZ may have significant implications for the operation and long-term performance of an underground nuclear waste repository. Various issues of concern need to be evaluated, such as processes creating fractures in the excavation damaged zone, the degree of permeability increase, and the potential for sealing or healing (with permeability reduction) in the zone. In recent years, efforts along these lines have been made for a potential repository in four rock types-crystalline rock, salt, indurated clay, and plastic clay-and these efforts have involved field, laboratory, and theoretical studies. The present work involves a synthesis of the ideas and issues that emerged from presentations and discussions on EDZ in these four rock types at a CLUSTER Conference and Workshop held in Luxembourg in November, 2003. First, definitions of excavation disturbed and excavation damaged zones are proposed. Then, an approach is suggested for the synthesis and intercomparison of geohydromechanical processes in the EDZ for the four rock types (crystalline rock, salt, indurated clay, and plastic clay). Comparison tables of relevant processes, associated factors, and modeling and testing techniques are developed. A discussion of the general state-of-the-art and outstanding issues are also presented. A substantial bibliography of relevant papers on the subject is supplied at the end of the paper.

  15. Spinel–rock salt transformation in LiCoMnO4−δ

    PubMed Central

    Reeves-McLaren, Nik; Sharp, Joanne; Beltrán-Mir, Héctor; Rainforth, W. Mark; West, Anthony R.

    2016-01-01

    The transformation on heating LiCoMnO4, with a spinel structure, to LiCoMnO3, with a cation-disordered rock salt structure, accompanied by loss of 25% of the oxygen, has been followed using a combination of diffraction, microscopy and spectroscopy techniques. The transformation does not proceed by a topotactic mechanism, even though the spinel and rock salt phases have a similar, cubic close-packed oxygen sublattice. Instead, the transformation passes through two stages involving, first, precipitation of Li2MnO3, leaving behind a Li-deficient, Co-rich non-stoichiometric spinel and, second, rehomogenization of the two-phase assemblage, accompanied by additional oxygen loss, to give the homogeneous rock salt final product; a combination of electron energy loss spectroscopy and X-ray absorption near edge structure analyses showed oxidation states of Co2+ and Mn3+ in LiCoMnO3. Subsolidus phase diagram determination of the Li2O-CoOx-MnOy system has established the compositional extent of spinel solid solutions at approximately 500°C. PMID:26997883

  16. Thermoelastic properties of rock-salt NaCl at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Santos, M. L. M.; Shukla, G.; Wentzcovitch, R. M.

    2014-12-01

    Rock-salt NaCl is an important mineral in our daily lives, in high pressure science/technology, and in the oil/gas industry. The latter has come to prominence since the discovery of deep water pre-salt structures containing great hydrocarbon reserves out of the SE coast of Brazil. The unique aspects of these regions, such as deep water (greater than 2 km below sea level) and deep hydrocarbon reserves (more than 5 km deep) are challenging for oil/gas explorations. Oil/gas field imaging algorithms require good velocity models for seismic wave-propagation within the salt layer. Despite its importance, there is still insufficient information on the elasticity of and sound velocities in NaCl at relevant P,T conditions. Here we report such properties in rock-salt NaCl at relevant P,T conditions as obtained by first principles (DFT) quasiharmonic calculations. We compare intermediate and final results with available experimental data on thermodynamics and thermoelastic properties and combine them for optimum accuracy. These results should be useful for and facilitate imaging pre-salt hydrocarbon reserves. Research supported by CAPES from Brazil, NSF/DMR, and NSF/EAR.

  17. Lead salt quantum effect structures

    NASA Astrophysics Data System (ADS)

    Partin, Dale L.

    1988-08-01

    Lead salt (V-VI) compounds have been grown epitaxially by a variety of growth techniques, such as molecular-beam epitaxy and hot-wall epitaxy. Recently, compositional superlattices and quantum-well heterostructures have been grown that exhibit strong quantum optical effects. These structures have been used to fabricate midinfrared diode lasers with greatly improved operating temperatures. Thus, it appears that these devices will continue to maintain a significant advantage over II-VI and III-V compound diode lasers. Doping superlattices have been made which possess enhanced minority carier properties. Ferromagnetic ordering in PbSnTe-MnTe alloys suggests potential areas for future work in magnetic field sensitivity devices. Lead salt quantum-effect structures are included.

  18. Model for transient creep of southeastern New Mexico rock salt

    SciTech Connect

    Herrmann, W; Wawersik, W R; Lauson, H S

    1980-11-01

    In a previous analysis, existing experimental data pertaining to creep tests on rock salt from the Salado formation of S.E. New Mexico were fitted to an exponential transient creep law. While very early time portions of creep strain histories were not fitted very well for tests at low temperatures and stresses, initial creep rates in particular generally being underestimated, the exponential creep law has the property that the transient creep strain approaches a finite limit with time, and is therefore desirable from a creep modelling point of view. In this report, an analysis of transient creep is made. It is found that exponential transient creep can be related to steady-state creep through a universal creep curve. The resultant description is convenient for creep analyses where very early time behavior is not important.

  19. Disordered lithium niobate rock-salt materials prepared by hydrothermal synthesis.

    PubMed

    Modeshia, Deena R; Walton, Richard I; Mitchell, Martin R; Ashbrook, Sharon E

    2010-07-14

    An investigation of the one-step hydrothermal crystallisation of lithium niobates reveals that reaction between Nb(2)O(5) and aqueous LiOH at 240 degrees C yields materials with a disordered rock-salt structure where the metals are statistically distributed over the cation sites. This contrasts with the well-studied reaction between Nb(2)O(5) and NaOH or KOH that produces ANbO(3) (A = Na, K) perovskites. Powder neutron diffraction shows that materials prepared at short reaction times and lower LiOH concentration (2.5 M) are lithium deficient and have a slight excess of niobium, but that at longer periods of reaction in 5 M LiOH, close to the ideal, stoichiometric Li(0.75)Nb(0.25)O composition is produced. Upon annealing this phase cleanly transforms into the known ordered rock-salt material Li(3)NbO(4), a process we have followed using thermodiffractometry, which indicates that transformation begins at approximately 700 degrees C. Solid-state (93)Nb and (7)Li NMR of the disordered and ordered rock-salt phases shows that both contain single metal sites but there is clear evidence for local disorder in the disordered samples. For the ordered material, NMR parameters derived from experiment are also compared to those calculated using density functional theory and are shown to be in good agreement. PMID:20442945

  20. Metallic sulfide deposits in Winnefield salt dome, Louisiana: evidence for episodic introduction of metalliferous brines during cap rock formation

    SciTech Connect

    Ulrich, M.R.

    1984-09-01

    Winnfield dome is a shallow piercement salt structure that penetrates Late Jurassic through early Tertiary siliciclastic and carbonate strata of the North Louisiana basin. Quarrying operations in the calcite and anhydrite portions of the cap rock have exposed zones of metallic sulfides and barite. A roughly laminated massive sulfide lens is exposed at the calcite to anhydrite transition zone. These sulfide concentrations are believed to have originated from the interaction of metalliferous basinal brines with reduced sulfur trapped within the cap rock. Textural relationships and variations in chemical compositions between the sulfide layers in the anhydrite portion of the cap rock suggest that distinct pulses of metalliferous brines were responsible for the sulfide concentrations. Anhydrite grains outside the mineralized areas are deformed and tightly intergrown. These textures suggest that mineralizing fluids were introduced episodically along the salt and anhydrite interface at the zone of salt dissolution before that portion of the anhydrite zone was compressed and accreted to overlying anhydrite cap rock. Therefore, the earliest formed sulfides originating by this mechanism occur at the top of the anhydrite cap rock zone, whereas the last sulfides to form are found at the base. Extensive sulfide concentrations along the anhydrite-calcite contact suggest that this contact also acted as a permeable zone allowing metalliferous brines into the cap rock. Textural and compositional relationships suggest that sulfides that formed along the anhydrite-calcite contact are locally superimposed on sulfides that formed at the salt-anhydrite contact.

  1. Radioactive waste isolation in salt: geochemistry of brine in rock salt in temperature gradients and gamma-radiation fields - a selective annotated bibliography

    SciTech Connect

    Hull, A.B.; Williams, L.B.

    1985-07-01

    Evaluation of the extensive research concerning brine geochemistry and transport is critically important to successful exploitation of a salt formation for isolating high-level radioactive waste. This annotated bibliography has been compiled from documents considered to provide classic background material on the interactions between brine and rock salt, as well as the most important results from more recent research. Each summary elucidates the information or data most pertinent to situations encountered in siting, constructing, and operating a mined repository in salt for high-level radioactive waste. The research topics covered include the basic geology, depositional environment, mineralogy, and structure of evaporite and domal salts, as well as fluid inclusions, brine chemistry, thermal and gamma-radiation effects, radionuclide migration, and thermodynamic properties of salts and brines. 4 figs., 6 tabs.

  2. Rock Pore Structure as Main Reason of Rock Deterioration

    NASA Astrophysics Data System (ADS)

    Ondrášik, Martin; Kopecký, Miloslav

    2014-03-01

    Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite. However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals. Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups - group N in which the pore water does not freeze

  3. Grain Boundary Wetting In The Stressed Rock Salt

    NASA Astrophysics Data System (ADS)

    Traskine, V.; Skvortsova, Z.; Barrallier, L.

    stress above 0.8 MPa tend to stop the brine infiltration. Extracting the intergranular energy distribution parameters from the Herring formula for the dihedral angles along triple lines allows to estimate the effec- tive increments to grain boundary energy due to shear stresses. A linear relationship between this interfacial energy term and the square of shear stress gives a formally Griffith-like criterion for GBW based on the interfacial and elastic energy balance. Applying the results to the rock salt formations will provide a new insight into the percolation approach to their transport characteristics.

  4. Effect of Dihedral Angle and Porosity on Percolating-Sealing Capacity of Texturally Equilibrated Rock Salt

    NASA Astrophysics Data System (ADS)

    Ghanbarzadeh, S.; Hesse, M. A.; Prodanovic, M.; Gardner, J. E.

    2013-12-01

    capillary entry pressure. This expanded knowledge of the salt textural behavior vs. depth could also improve drilling operations in salt. Second, a series of experiments in different P-T conditions was carried out to investigate the actual shape of equilibrated channels in salt. The synthetic salt samples were scanned at the High Resolution X-ray CT Facility at the Department of Geological Science, the University of Texas at Austin with resolution in 1-6 micron range. The experimental results show both equilibrated (tubular pores) and non-equilibrated (planar features) in salt structure. Image processing was carried out by two open source software programs: ImageJ, which is a public domain Java image processing program, and 3DMA-Rock, which is a software package for quantitative analyzing of the pore space in three-dimensional X-ray computed microtomographic images of rock. We obtain medial axis and medial surface of the pore space, as well as find and characterize the corresponding pore-throat network. We also report permeability of the pore space computed using Palabos software.

  5. Growth stimulation and proteomic studies of halococci from Permo-Triassic rock salt

    NASA Astrophysics Data System (ADS)

    Legat, A.; Gruber, C.; Stan-Lotter, H.

    2003-04-01

    Viable extremely halophilic archaebacteria were isolated from Austrian Permo-Triassic rock salt and identified as Halococcus species. Growth of these isolates was greatly stimulated by addition of sea salts, Alpine rock salt and rock salt from a Permian deposit in Carrickfergus, Northern Ireland (IS). One-dimensional whole cell protein patterns of strains Hcc. salifodinae and Hcc. dombrowskii were different whether cells were grown in the presence or absence of IS, which suggested influences by unknown components in the rock salt on halobacterial metabolism. Studies of the halococcal proteomes by two-dimensional gel electrophoresis (isoelectric focusing and sodium dodecylsulfate polyacrylamide gele electrophoresis) were begun and revealed differences in the fractions of higher and lower molecular weight components.

  6. Evaluation of Five Sedimentary Rocks Other Than Salt for Geologic Repository Siting Purposes

    SciTech Connect

    Croff, A.G.; Lomenick, T.F.; Lowrie, R.S.; Stow, S.H.

    2003-11-15

    The US Department of Energy (DOE), in order to increase the diversity of rock types under consideration by the geologic disposal program, initiated the Sedimary ROck Program (SERP), whose immediate objectiv eis to evaluate five types of secimdnary rock - sandstone, chalk, carbonate rocks (limestone and dolostone), anhydrock, and shale - to determine the potential for siting a geologic repository. The evaluation of these five rock types, together with the ongoing salt studies, effectively results in the consideration of all types of relatively impermeable sedimentary rock for repository purposes. The results of this evaluation are expressed in terms of a ranking of the five rock types with respect to their potential to serve as a geologic repository host rock. This comparative evaluation was conducted on a non-site-specific basis, by use of generic information together with rock evaluation criteria (RECs) derived from the DOE siting guidelines for geologic repositories (CFR 1984). An information base relevant to rock evaluation using these RECs was developed in hydrology, geochemistry, rock characteristics (rock occurrences, thermal response, rock mechanics), natural resources, and rock dissolution. Evaluation against postclosure and preclosure RECs yielded a ranking of the five subject rocks with respect to their potential as repository host rocks. Shale was determined to be the most preferred of the five rock types, with sandstone a distant second, the carbonate rocks and anhydrock a more distant third, and chalk a relatively close fourth.

  7. Forensic Analysis of the May 2014 West Salt Creek Rock Avalanche in Western Colorado

    NASA Astrophysics Data System (ADS)

    Coe, J. A.; Baum, R. L.; Allstadt, K.; Kochevar, B. F.; Schmitt, R. G.; Morgan, M. L.; White, J. L.; Stratton, B. T.; Hayashi, T. A.; Kean, J. W.

    2015-12-01

    The rain-on-snow induced West Salt Creek rock avalanche occurred on May 25, 2014 on the northern flank of Grand Mesa. The avalanche was rare for the contiguous U.S. because of its large size (59 M m3) and high mobility (Length/Height=7.2). To understand the avalanche failure sequence, mechanisms, and mobility, we conducted a forensic analysis using large-scale (1:1000) structural mapping and seismic data. We used high-resolution, Unmanned Aircraft System (UAS) imagery as a base for our field mapping and analyzed seismic data from 22 broadband stations (distances <656 km) and one short-period network. We inverted broadband data to derive a time series of forces that the avalanche exerted on the earth and tracked these forces using curves in the avalanche path. Our results revealed that the rock avalanche was a cascade of landslide events, rather than a single massive failure. The sequence began with a landslide/debris flow that started about 10 hours before the main avalanche. The main avalanche lasted just over 3 minutes and traveled at average velocities ranging from 15 to 36 m/s. For at least two hours after the avalanche ceased movement, a central, hummock-rich, strike-slip bound core continued to move slowly. Following movement of the core, numerous shallow landslides, rock slides, and rock falls created new structures and modified topography. Mobility of the main avalanche and central core were likely enhanced by valley floor material that liquefied from undrained loading by the overriding avalanche. Although the base was likely at least partially liquefied, our mapping indicates that the overriding avalanche internally deformed predominantly by sliding along discrete shear surfaces in material that was nearly dry and had substantial frictional strength. These results indicate that the West Salt Creek avalanche, and probably other long-traveled avalanches, could be modeled as two layers: a liquefied basal layer; and a thicker and stronger overriding layer.

  8. Numerical Simulation on Open Wellbore Shrinkage and Casing Equivalent Stress in Bedded Salt Rock Stratum

    PubMed Central

    Liu, Jianjun

    2013-01-01

    Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength. PMID:24198726

  9. Structure of liquid trivalent salts

    SciTech Connect

    Price, D.L.; Saboungi, M.L.; Howells, W.S.; Tosi, M.P.

    1993-04-01

    Total neutron scattering measurements have been made on three trivalent molten salts: InCl{sub 3} (605C), BiCl{sub 3}(300C) and BiI{sub 3} (420C). Results are discussed in the general context of ordering, bonding and macroscopic properties of trivalent molten salts.

  10. Structure of liquid trivalent salts

    SciTech Connect

    Price, D.L.; Saboungi, M.L. . Materials Science Div.); Howells, W.S. ); Tosi, M.P. )

    1993-04-01

    Total neutron scattering measurements have been made on three trivalent molten salts: InCl[sub 3] (605C), BiCl[sub 3](300C) and BiI[sub 3] (420C). Results are discussed in the general context of ordering, bonding and macroscopic properties of trivalent molten salts.

  11. A New Improved Failure Criterion for Salt Rock Based on Energy Method

    NASA Astrophysics Data System (ADS)

    Hao, T. S.; Liang, W. G.

    2016-05-01

    A non-linear triple shear energy yield criterion for salt rock is presented in this paper. It is the development of the triple shear energy yield criterion, of which the Mohr-Coulomb criterion can be seen as a special case. The main factors affecting the primary strength of salt rock, such as the mean stress and the Lode angle, are considered in the non-linear triple shear energy yield criterion. The non-linear new criterion provides the non-linear change trend of salt strength both in the I 1- J 2 stress space and in the deviatoric plane. Comparative study between the non-linear criterion predictions and experimental results of salt rock shows that the non-linear triple shear energy yield criterion fits quite well with both conventional triaxial test data and the true triaxial test data. For Maha Sarakham salt, the predictive capability of the non-linear triple shear energy yield criterion is clearly better than that of some other criteria used by Sriapai, such as modified Lade criterion, 3-D Hoek, and Brown criterion, Drucker-Prager criterion et al. The availability of the non-linear triple shear energy yield criterion can also be confirmed by comparative analysis between theoretical values and experimental values for non-salt rocks. So the non-linear triple shear energy yield criterion is a general failure criterion for rocks fractured by shear stress.

  12. Sulfate-dependent Anaerobic Oxidation of Methane as a Generation Mechanism for Calcite Cap Rock in Gulf Coast Salt Domes

    NASA Astrophysics Data System (ADS)

    Caesar, K. H.; Kyle, R.; Lyons, T. W.; Loyd, S. J.

    2015-12-01

    Gulf Coast salt domes, specifically their calcite cap rocks, have been widely recognized for their association with significant reserves of crude oil and natural gas. However, the specific microbial reactions that facilitate the precipitation of these cap rocks are still largely unknown. Insight into the mineralization mechanism(s) can be obtained from the specific geochemical signatures recorded in these structures. Gulf Coast cap rocks contain carbonate and sulfur minerals that exhibit variable carbon (d13C) and sulfur isotope (δ34S) signatures. Calcite d13C values are isotopically depleted and show a large range of values from -1 to -52‰, reflecting a mixture of various carbon sources including a substantial methane component. These depleted carbon isotope compositions combined with the presence of abundant sulfide minerals in cap rocks have led to interpretations that invoke microbial sulfate reduction as an important carbonate mineral-yielding process in salt dome environments. Sulfur isotope data from carbonate-associated sulfate (CAS: trace sulfate incorporated within the carbonate mineral crystal lattice) provide a more direct proxy for aqueous sulfate in salt dome systems and may provide a means to directly fingerprint ancient sulfate reduction. We find CAS sulfur isotope compositions (δ34SCAS) significantly greater than those of the precursor Jurassic sulfate-salt deposits (which exhibit δ34S values of ~ +15‰). This implies that cap rock carbonate generation occurred via microbial sulfate reduction under closed-system conditions. The co-occurrence of depleted carbonate d13C values (< ~30‰) and the enriched δ34SCAS values are evidence for sulfate-dependent anaerobic oxidation of methane (AOM). AOM, which has been shown to yield extensive seafloor carbonate authigenesis, is also potentially partly responsible for the carbonate minerals of the Gulf Coast calcite cap rocks through concomitant production of alkalinity. Collectively, these data shed

  13. Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

    USGS Publications Warehouse

    Anderson, N.L.; Hopkins, J.; Martinez, A.; Knapp, R.W.; Macfarlane, P.A.; Watney, W.L.; Black, R.

    1994-01-01

    Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: 1. (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the

  14. Experimental Investigation of Two-Phase Flow in Rock Salt

    SciTech Connect

    Malama, Bwalya; Howard, Clifford L.

    2014-07-01

    This Test Plan describes procedures for conducting laboratory scale flow tests on intact, damaged, crushed, and consolidated crushed salt to measure the capillary pressure and relative permeability functions. The primary focus of the tests will be on samples of bedded geologic salt from the WIPP underground. However, the tests described herein are directly applicable to domal salt. Samples being tested will be confined by a range of triaxial stress states ranging from atmospheric pressure up to those approximating lithostatic. Initially these tests will be conducted at room temperature, but testing procedures and equipment will be evaluated to determine adaptability to conducting similar tests under elevated temperatures.

  15. The Influence of the De-Icing Salt on the Deterioration of Rock Materials Used in Monumental Buildings

    NASA Astrophysics Data System (ADS)

    Kłopotowska, Agnieszka Katarzyna; Łukaszewski, Paweł

    2013-09-01

    The de-icing salt has been used for decades to increase safety on the roads and sidewalks. In Poland, mainly the sodium chloride is used in order to maintain the roads in good condition during winter. Like other salts used for surface de-icing, it depresses the freezing point to lower temperatures and has an additional thermal effect by an exothermic reaction. However, this salt causes the accumulation of chlorides in the walls and stone buildings contributing to the deterioration of these facilities. The paper addresses the issue of the influence of salt solutions on the structure and geomechanical properties of rocks at negative temperatures. The study was conducted on the basis of cyclic tests which simulate complex action of both the negative temperature and the salty environment. The conditions for the tests were chosen so as to reflect the actual conditions of the winter in Poland. During the tests, the longitudinal wave propagation velocity, changes in weights of the samples as well as visual changes were recorded which allowed continuous tracking of occurring changes. At the end of the tests, the rock samples were subjected to uniaxial compressive tests. For this purpose, four lithological types were chosen, representing the sedimentary rocks: clastic and carbonate, widely used in stone constructions.

  16. Tests of US rock salt for long-term stability of CAES reservoirs

    SciTech Connect

    Gehle, R.M.; Thoms, R.L.

    1986-01-01

    This is a report on laboratory tests to assess the effects of compressed air energy storage (CAES) on rock salt within the US. The project included a conventional laboratory test phase, with triaxial test machines, and a bench-scale test phase performed in salt mines in southern Louisiana. Limited numerical modeling also was performed to serve as a guide in selecting test layouts and for interpreting test data.

  17. Estimating Rheological Parameters of Anhydrite from Folded Evaporite sequences: Implications for Internal Dynamics of Salt Structure

    NASA Astrophysics Data System (ADS)

    Adamuszek, Marta; Dabrowski, Marcin; Schmalholz, Stefan M.; Urai, Janos L.; Raith, Alexander

    2015-04-01

    Salt structures have been identified as a potential target for hydrocarbon, CO2, or radioactive waste storage. The most suitable locations for magazines are considered in the thick and relatively homogeneous rock salt layers. However, salt structures often consist of the evaporite sequence including rock salt intercalated with other rock types e.g.: anhydrite, gypsum, potassium and magnesium salt, calcite, dolomite, or shale. The presence of such heterogeneities causes a serious disturbance in the structure management. Detailed analysis of the internal architecture and internal dynamics of the salt structure are crucial for evaluating them as suitable repositories and also their long-term stability. The goal of this study is to analyse the influence of the presence of anhydrite layers on the internal dynamics of salt structures. Anhydrite is a common rock in evaporite sequences. Its physical and mechanical properties strongly differ from the properties of rock salt. The density of anhydrite is much higher than the density of salt, thus anhydrite is likely to sink in salt causing the disturbance of the surrounding structures. This suggestion was the starting point to the discussion about the long-term stability of the magazines in salt structures [1]. However, the other important parameter that has to be taken into account is the viscosity of anhydrite. The high viscosity ratio between salt and anhydrite can restrain the layer from sinking. The rheological behaviour of anhydrite has been studied in laboratory experiments [2], but the results only provide information about the short-term behaviour. The long-term behaviour can be best predicted using indirect methods e.g. based on the analysis of natural structures that developed over geological time scale. One of the most promising are fold structures, the shape of which is very sensitive to the rheological parameters of the deforming materials. Folds can develop in mechanically stratified materials during layer

  18. Halophilic archaea cultivated from surface sterilized middle-late eocene rock salt are polyploid.

    PubMed

    Jaakkola, Salla T; Zerulla, Karolin; Guo, Qinggong; Liu, Ying; Ma, Hongling; Yang, Chunhe; Bamford, Dennis H; Chen, Xiangdong; Soppa, Jörg; Oksanen, Hanna M

    2014-01-01

    Live bacteria and archaea have been isolated from several rock salt deposits of up to hundreds of millions of years of age from all around the world. A key factor affecting their longevity is the ability to keep their genomic DNA intact, for which efficient repair mechanisms are needed. Polyploid microbes are known to have an increased resistance towards mutations and DNA damage, and it has been suggested that microbes from deeply buried rock salt would carry several copies of their genomes. Here, cultivable halophilic microbes were isolated from a surface sterilized middle-late Eocene (38-41 million years ago) rock salt sample, drilled from the depth of 800 m at Yunying salt mine, China. Eight unique isolates were obtained, which represented two haloarchaeal genera, Halobacterium and Halolamina. We used real-time PCR to show that our isolates are polyploid, with genome copy numbers of 11-14 genomes per cell in exponential growth phase. The ploidy level was slightly downregulated in stationary growth phase, but the cells still had an average genome copy number of 6-8. The polyploidy of halophilic archaea living in ancient rock salt might be a factor explaining how these organisms are able to overcome the challenge of prolonged survival during their entombment. PMID:25338080

  19. Halophilic Archaea Cultivated from Surface Sterilized Middle-Late Eocene Rock Salt Are Polyploid

    PubMed Central

    Jaakkola, Salla T.; Zerulla, Karolin; Guo, Qinggong; Liu, Ying; Ma, Hongling; Yang, Chunhe; Bamford, Dennis H.; Chen, Xiangdong; Soppa, Jörg; Oksanen, Hanna M.

    2014-01-01

    Live bacteria and archaea have been isolated from several rock salt deposits of up to hundreds of millions of years of age from all around the world. A key factor affecting their longevity is the ability to keep their genomic DNA intact, for which efficient repair mechanisms are needed. Polyploid microbes are known to have an increased resistance towards mutations and DNA damage, and it has been suggested that microbes from deeply buried rock salt would carry several copies of their genomes. Here, cultivable halophilic microbes were isolated from a surface sterilized middle-late Eocene (38–41 million years ago) rock salt sample, drilled from the depth of 800 m at Yunying salt mine, China. Eight unique isolates were obtained, which represented two haloarchaeal genera, Halobacterium and Halolamina. We used real-time PCR to show that our isolates are polyploid, with genome copy numbers of 11–14 genomes per cell in exponential growth phase. The ploidy level was slightly downregulated in stationary growth phase, but the cells still had an average genome copy number of 6–8. The polyploidy of halophilic archaea living in ancient rock salt might be a factor explaining how these organisms are able to overcome the challenge of prolonged survival during their entombment. PMID:25338080

  20. Three dimensional finite element simulations of room and pillar mines in rock salt

    SciTech Connect

    Hoffman, E.L.; Ehgartner, B.L.

    1996-05-01

    3-D quasistatic finite element codes are being used at Sandia to simulate large room and pillar mines in rock salt. The two examples presented in this paper are of mines supported by US DOE, under the auspices of the Strategic Petroleum Reserve program. One of the mines is presently used as an oil storage facility. These simulations, validated by field measurements and observations, have provided valuable insight into the failure mechanisms of room and pillar mines in rock salt. The calculations provided the basis for further investigation and the ultimate decision to decommission the DOE oil storage facility.

  1. Radiation defects and energy storage in natural polycrystalline rock salt. Results of an in-situ test in the Permian rock salt of the Asse

    SciTech Connect

    Gies, H.; Rothfuchs, T.; Celma, A.G.; Haas, J.B.M. de; Pederson, L.

    1994-12-31

    Radiation damage development and the corresponding energy storage in pure undeformed single crystals have frequently been studied in laboratory experiments, however little is known of irradiation experiments on natural rock salt (polycrystalline, deformed and impure) under geological conditions. The relevance of these parameters to the defect formation was revealed by a joint United States/Federal Republic of Germany in-situ test in the Asse Mine. Natural rock salt was heated and irradiated using Co-60 sources. Calculations of the amount of halite expected to be decomposed by radiolysis during the experiment were performed using the 1985 version of the Jain-Lidiard model. Qualitative agreement between theory and analyses was found for all the performed analyses. Quantitative and qualitative deviations of the natural samples behaviour from that of single undeformed crystals were observed and attributed to the influence of sulfatic admixtures, polycrystallinity and strain on radiation damage development and anneal. Special chemical methods, such as iodometric titration and uv-visible spectroscopy were applied in order to measure the hypochlorite ion, which forms in irradiated salt. Composite samples located closet to the Co-60 source averaged 0,4 micromoles neutral chlorine atoms per gram salt, a factor of two more than from other positions. Uv-vis analyses revealed more than a factor of ten greater neutral chlorine concentrations in coloured halite. Similarly, optical absorption measurements indicated a factor of ten difference in sodium metal colloid concentrations.

  2. Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

    NASA Astrophysics Data System (ADS)

    Marketos, G.; Spiers, C. J.; Govers, R.

    2016-06-01

    Accurate forward modeling of surface subsidence above producing hydrocarbons reservoirs requires an understanding of the mechanisms determining how ground deformation and subsidence evolve. Here we focus entirely on rock salt, which overlies a large number of reservoirs worldwide, and specifically on the role of creep of rock salt caprocks in response to production-induced differential stresses. We start by discussing available rock salt creep flow laws. We then present the subsidence evolution above an axisymmetric finite element representation of a generic reservoir that extends over a few kilometers and explore the effects of rock salt flow law choice on the subsidence response. We find that if rock salt creep is linear, as appropriate for steady state flow by pressure solution, the subsidence response to any pressure reduction history contains two distinct components, one that leads to the subsidence bowl becoming narrower and deeper and one that leads to subsidence rebound and becomes dominant at later stages. This subsidence rebound becomes inhibited if rock salt deforms purely through steady state power law creep at low stresses. We also show that an approximate representation of transient creep leads to relatively small differences in subsidence predictions. Most importantly, the results confirm that rock salt flow must be modeled accurately if good subsidence predictions are required. However, in practice, large uncertainties exist in the creep behavior of rock salt, especially at low stresses. These are a consequence of the spatial variability of rock salt physical properties, which is practically impossible to constrain. A conclusion therefore is that modelers can only resort to calculating bounds for the subsidence evolution above producing rock salt-capped reservoirs.

  3. Deformation of allochthonous salt and evolution of related salt-structural systems, eastern Louisiana Gulf Coast

    SciTech Connect

    Schuster, D.C.

    1996-12-31

    Salt tectonics in the northern Gulf of Mexico involves both vertical diapirism and lateral silling or flow of salt into wings and tablets (sheets). Combinations of these two modes of salt deformation, concurrent with sediment loading and salt evacuation, have produced complex structures in the coastal and offshore region of southeastern Louisiana, a prolific oil and gas province. Many large growth faults and salt domes in the study area root into intra-Tertiary salt welds that were formerly occupied by allochthonous salt tablets. Two end-member structural systems involving evacuation of former tabular salt are recognized: roho systems and stepped counter-regional systems. Both end-member systems share a similar multi-staged evolution, including (1) initial formation of a south-leaning salt dome or wall sourced from the Jurassic salt level; (2) progressive development into a semi-tabular allochthonous salt body; and (3) subsequent loading, evacuation, and displacement of the tabular salt into secondary domes. In both systems, it is not uncommon to find salt displaced as much as 16-24 km south of its autochthonous source, connected by a horizontal salt weld to an updip, deflated counter-regional feeder. Although both end-member structural systems may originate before loading of allochthonous salt having grossly similar geometry, their final structural configurations after loading and salt withdrawal are distinctly different. Roho systems are characterized by large-displacement, listric, south-dipping growth faults that sole into intra-Tertiary salt welds marked by high-amplitude reflections continuous with residual salt masses. Salt from the former salt tablets has been loaded and squeezed laterally and downdip. Stepped counter-regional systems, in contrast, comprise large salt domes and adjacent large-displacement, north-dipping growth faults that sole into intra-Tertiary salt welds before stepping down again farther north.

  4. Evolution of rheologically heterogeneous salt structures: a case study from the northeast of the Netherlands

    NASA Astrophysics Data System (ADS)

    Raith, A. F.; Strozyk, F.; Visser, J.; Urai, J. L.

    2015-07-01

    At the first order salt structures are controlled by the low flow strength of evaporites and by the tectonic boundary conditions. Rheological contrasts within an evaporite body have an important effect on the evolution of the internal structure of salt, but how this mechanical layering affects salt deformation at different scales is not well known. The potassium-magnesium salts (K-Mg salts) carnallite and bischofite are prime examples of layers with much lower effective viscosity than rock salt: their low viscosity presents serious drilling hazards but also allows squeeze solution mining. In contrast, anhydrite and carbonate layers (stringers) in salt are much stronger than halite. In this study, we used high-resolution 3-D seismic and well data to study the evolution of the Veendam and Slochteren salt pillows at the southern boundary of the Groningen High, northern Netherlands. Here the rock salt layers contain both the mechanically stronger Zechstein III Anhydrite-Carbonate stringer and the weaker K-Mg salts, providing an example of extreme rheological heterogeneities in salt structures. The internal structure of the two salt pillows shows areas in which the K-Mg salt-rich ZIII 1b layer is much thicker than elsewhere, in combination with a complexly ruptured and folded ZIII Anhydrite-Carbonate stringer. Thickness maps of supra-salt sediments and well data are used to infer the initial depositional architecture of the K-Mg salts and their deformation history. Results suggest that active faulting and the resulting depressions of the Zechstein surface above a Rotliegend graben caused the local accumulation of bittern brines and precipitation of the thick K-Mg salts. During the first phase of salt flow and withdrawal from the Veendam area, under differential loading by Buntsandstein sediments, the ZIII stringer was boudinaged while the lens of Mg salts remained relatively undeformed. This was followed by a convergence stage, when the K-Mg salt-rich layers were

  5. Sphalerite-rock salt phase transition in ZnMnSe heterostructures

    SciTech Connect

    Litvinov, D.; Gerthsen, D.; Rosenauer, A.; Daniel, B.; Hetterich, M.

    2004-08-02

    We report on the investigation of epitaxial MnSe layers grown on ZnSe by transmission electron microscopy. MnSe/ZnSe superlattices (SLs) with different nominal MnSe thicknesses t{sub MnSe} between 2 and 20 monolayers (MLs) were investigated, which were grown by molecular-beam epitaxy on GaAs(001) substrates. Composition profiles of the SLs were evaluated by the measurement of local (002) lattice parameters in growth direction. A MnSe deposition between 2 and 4 MLs on ZnSe leads to the formation of intermixed Zn{sub 1-x}Mn{sub x}Se layers with sphalerite structure and a Mn concentration x increasing from 50% to 90%. For MnSe layers with a thickness between 6 and 20 ML, we observe 5-10 nm small MnSe inclusions with a rock salt structure embedded in sphalerite Zn{sub 1-x}Mn{sub x}Se with approximately 90%Mn.

  6. Pure water injection into porous rock with superheated steam and salt in a solid state

    NASA Astrophysics Data System (ADS)

    Montegrossi, G.; Tsypkin, G.; Calore, C.

    2012-04-01

    Most of geothermal fields require injection of fluid into the hot rock to maintain pressure and productivity. The presence of solid salt in porous space may cause an unexpected change in the characteristics of the reservoir and produced fluids, and dramatically affect the profitability of the project. We consider an injection problem of pure water into high temperature geothermal reservoir, saturated with superheated vapour and solid salt. Pure water moves away from injection point and dissolves solid salt. When salty water reaches the low-pressure hot domain, water evaporation occurs and, consequently, salt precipitates. We develop a simplified analytical model of the process and derive the similarity solutions for a 1-D semi-infinite reservoir. These solutions are multi-valued and describe the reduction in permeability and porosity due to salt precipitation at the leading boiling front. If the parameters of the system exceed critical values, then similarity solution ceases to exist. We identify this mathematical behaviour with reservoir sealing in the physical system. The TOUGH2-EWASG code has been used to verify this hypothesis and investigate the precipitate formation for an idealized bounded 1-D geothermal system of a length of 500 m with water injection at one extreme and fluid extraction at the other one. Both boundaries are kept at constant pressure and temperature. The result for the semi-infinite numerical model show that the monotonic grow of the solid salt saturation to reach asymptotic similarity solution generally occurs over a very large length starting from the injection point. Reservoir sealing occurs if solid salt at the initial state occupies a considerable part of the porous space. Numerical experiments for the bounded 500 m system demonstrate that a small amount of salt is enough to get reservoir sealing. Generally, salt tend to accumulate near the production well, and salt plug forms at the elements adjacent to the extraction point. This type

  7. Structural evolution of Alpine salt deposits, Austria and Bavaria

    NASA Astrophysics Data System (ADS)

    Leitner, Ch.; Neubauer, F.; Genser, H.; Borojevic Sostaric, S.

    2009-04-01

    Structural evolution of Alpine salt deposits, Austria and Bavaria Alpine salt deposits consist of a tectonic melange of rocksalt and shale called haselgebirge representing the Haselgebirge Formation of Permian to Early Triassic age and mainly exposed within the central and eastern Northern Calcareous Alps. The initial evaporitic sediments were transformed into a breccia (protocataclasite, mylonite) during Alpine orogeny. Residual rocks of shale, anhydrite, polyhalite, sandstone and limestone float as isolated bodies in the haselgebirge matrix. Field investigations of foliation, halite mineral lineation, fold axis, veins and the overall present slickensides in shale revealed an individual history for all investigated mines (Dürrnberg, Berchtesgaden, Altaussee, in part Hallstatt). Ar-Ar dating of various micostructural types of polyhalite yield several preliminary age groups: 235 Ma, 180 Ma, and 110 Ma. Fluid inclusion measurements on anhydrite together with vitrinite reflectance data showed that temperatures of 140-180 °C were reached in Berchtesgaden and around 250° C in Altaussee. Microstructural analysis of anhydrite reveals strong stretching structures with lobate grain boundaries and the fomation of large anhydrite crystals in polyhalite (locally called muriazite). Rock salt and Haselgebirge samples were gamma-irradiated to intensify contrasts in thin section analysis. No primary structures like fluid inclusion bands or chevrons were found. The oldest visible parts are innner cores of large residual grains. All other types of grains suffered grain size reduction during the subsequent deformation. Using subgrain piezometry, high differential stresses of around 5 MPa formed the present microstructure. The Alpine rock salt deposits suffered a complex deformation history. A first peak was the formation of polyhalite veins, 235 Ma ago. The overburden was around 800 m (Rantitsch & Russegger, 2005) and first differentiation of the sea floor occurred (Mandl, 1984

  8. Experimental research on thermal damage of Yingcheng Mine rock salt with ultrasonic wave testing

    NASA Astrophysics Data System (ADS)

    Chen, J.; Tang, H.; Yang, C.

    2009-12-01

    Because of the special mechanical properties (creep behavior, damage and healing, low permeability), rock salt formation can be used for the high level radioactive waste disposal, and the thermal damage property of rock salt is important issue for the stability and sealing of the cavern. For investigation of the thermal damage characteristic of Yingcheng Mine rock salt (Hubei Provence, P.R. China), a series of ultrasonic wave velocity testing during rising temperature (without confining pressure, 20-270 centigrade) were carried out. From the experimental data,the ultrasonic wave velocity, the dynamical modulus (Young's modulus, shear modulus and bulk modulus ) and the dynamical Poisson's (calculated from the ultrasonic wave velocity) ratio decrease during rising temperature. The relationship of the ultrasonic wave velocity and the dynamical modulus between temperature can be expressed by exponential functions. Experimental phenomenon and the ultrasonic wave velocity, especially the spectrum analysis reveals that the thermal damage evolves with the temperature. But there is no phenomena indicates the “critical temperature” and damage self-healing due to the temperature.

  9. Effect of simulated sampling disturbance on creep behaviour of rock salt

    NASA Astrophysics Data System (ADS)

    Guessous, Z.; Gill, D. E.; Ladanyi, B.

    1987-10-01

    This article presents the results of an experimental study of creep behaviour of a rock salt under uniaxial compression as a function of prestrain, simulating sampling disturbance. The prestrain was produced by radial compressive loading of the specimens prior to creep testing. The tests were conducted on an artifical salt to avoid excessive scattering of the results. The results obtained from several series of single-stage creep tests show that, at short-term, the creep response of salt is strongly affected by the preloading history of samples. The nature of this effect depends upon the intensity of radial compressive preloading, and its magnitude is a function of the creep stress level. The effect, however, decreases with increasing plastic deformation, indicating that large creep strains may eventually lead to a complete loss of preloading memory.

  10. Numerical modelling of the evolution of the salt diapiric internal structure

    NASA Astrophysics Data System (ADS)

    Adamuszek, Marta; Dabrowski, Marcin

    2014-05-01

    Evaporate series are composed of a range of interbedded rock types such as carbonates (calcite, dolomite), sulphates (anhydrite, gypsum), and chlorides (rock salt, potassium and magnesium salt). The presence of evaporates particularly with thick salt layers within sedimentary basins significantly influences their tectonic evolution. This is due to unique properties of salt, which cause that salt buried under sediments becomes buoyant and migrates towards the surface promoting development of diapiric structures. The intensive complex deformation that operates on the layered evaporates sequence leads to the development of a complicated diapir internal architecture. Varying material properties such as viscosity and density of different rock types in the evaporate series contribute to the complexity of the formed structures. We numerically investigate the initiation and evolution of tectonic structures within the salt diapirs comprising mechanically stratified evaporate series. We analyse the role of parameters such as mechanical properties of the layered evaporate series and the overburden rocks, the initial spatial arrangement of different rock types, the rate of sedimentation of the overburden rocks, and various deformation regimes. In the study, we focus on the relationship between the structures such as folds and boudinage structures that develop on a small-scale (corresponding to the outcrop scale in the salt mine galleries) and a large-scale (corresponding to the whole diapir scale). Additionally, the influence of the internal structure development on the evolution of the overall diapir shape is examined. In the numerical model, we use non-linear viscous rheology for the evaporate series and the overburden. We solve an incompressible Stokes equation in the presence of the gravity using the finite element method solver MILAMIN [1]. The diapir evolution is simulated in two dimensions. The development of complex structures is analysed using the resolved interface

  11. En echelon crack-arrays in potash salt rock

    NASA Astrophysics Data System (ADS)

    Lajtai, E. Z.; Carter, B. J.; Duncan, E. J. S.

    1994-04-01

    There are two types of fracture patterns in the yield pillars of the potash mines of Saskatchewan. The individual members of both patterns are tensile (extension) fractures that propagate parallel with the maximum principal stress trajectory (perpendicular to the minimum principal stress). The difference between the two patterns lies in the arrangement of the member fractures. In the en echelon tensile crack-array, the macroscopic fracture consists of individual tensile cracks that are slightly offset from each other. They have only a small overlap and the child crack seems to form randomly on either side of its parent. Consequently, the en echelon tensile crack-array inherits the axial orientation of its members. In contrast, the tensile cracks of an en echelon shear crack-array, have a larger overlap and their lateral displacement from each other is biased in one direction. Therefore, the crack-array is no longer axial but inclined 20 25 degrees from the maximum principal stress direction. With increasing stress, the shear crack-array often collapses, forming the envelope or hourglass structures of the potash mines.

  12. MODELING UNDERGROUND STRUCTURE VULNERABILITY IN JOINTED ROCK

    SciTech Connect

    R. SWIFT; D. STEEDMAN

    2001-02-01

    The vulnerability of underground structures and openings in deep jointed rock to ground shock attack is of chief concern to military planning and security. Damage and/or loss of stability to a structure in jointed rock, often manifested as brittle failure and accompanied with block movement, can depend significantly on jointed properties, such as spacing, orientation, strength, and block character. We apply a hybrid Discrete Element Method combined with the Smooth Particle Hydrodynamics approach to simulate the MIGHTY NORTH event, a definitive high-explosive test performed on an aluminum lined cylindrical opening in jointed Salem limestone. Representing limestone with discrete elements having elastic-equivalence and explicit brittle tensile behavior and the liner as an elastic-plastic continuum provides good agreement with the experiment and damage obtained with finite-element simulations. Extending the approach to parameter variations shows damage is substantially altered by differences in joint geometry and liner properties.

  13. Evolution of rheologically heterogeneous salt structures: a case study from the NE Netherlands

    NASA Astrophysics Data System (ADS)

    Raith, A. F.; Strozyk, F.; Visser, J.; Urai, J. L.

    2016-01-01

    The growth of salt structures is controlled by the low flow strength of evaporites and by the tectonic boundary conditions. The potassium-magnesium salts (K-Mg salts) carnallite and bischofite are prime examples of layers with much lower effective viscosity than halite: their low viscosity presents serious drilling hazards but also allows squeeze solution mining. In contrast, intrasalt anhydrite and carbonate layers (stringers) are much stronger than halite. These rheological contrasts within an evaporite body have an important control on the evolution of the internal structure of salt, but how this mechanical layering affects salt deformation at different scales is not well known. In this study, we use high-resolution 3-D seismic and well data to study the evolution of the Veendam and Slochteren salt pillows at the southern boundary of the Groningen High, northern Netherlands. Here the rock salt layers contain both the mechanically stronger Zechstein III Anhydrite-Carbonate stringer and the weaker K-Mg salts, thus we are able to assess the role of extreme rheological heterogeneities on salt structure growth. The internal structure of the two salt pillows shows areas in which the K-Mg salt-rich ZIII 1b layer is much thicker than elsewhere, in combination with a complexly ruptured and folded ZIII Anhydrite-Carbonate stringer. Thickness maps of supra-salt sediments and well data are used to infer the initial depositional architecture of the K-Mg salts and their deformation history. Results suggest that faulting and the generation of depressions on the top Zechstein surface above a Rotliegend graben caused the local accumulation of bittern brines and precipitation of thick K-Mg salts. During the first phase of salt flow and withdrawal from the Veendam area, under the influence of differential loading by Buntsandstein sediments, the ZIII stringer was boudinaged while the lens of Mg salts remained relatively undeformed. This was followed by a convergence stage, when the

  14. Creep Behaviour of Bischofite, Carnallite and Mixed Bischofite-Carnallite Salt Rock

    NASA Astrophysics Data System (ADS)

    De Bresser, J. H. P.; Muhammad, N.; Spiers, C. J.; Peach, C. J.

    2014-12-01

    Some salt deposits contain the valuable magnesium and potassium salts bischofite and carnallite, as well as halite, in the form of pure and mixed layers. During extraction of such salts from the subsurface by solution mining, the material in the undissolved walls will flow into the caverns. In order to accurately predict the flow of wall rock material, feasible production rates and related subsidence, a good understanding of the creep behaviour of bischofite, carnallite and mixed salt rocks under in situ conditions is required. We have conducted conventional triaxial compression tests on polycrystalline bischofite, carnallite and mixed bischofite-carnallite-halite rock samples machined from natural cores. The experiments were carried out at true in situ P-T conditions of 70°C and 40 MPa confining pressure. All experiments consisted of strain rate stepping runs, applying strain rates in the range 10-5 to 10-8 s-1, reaching 2-4% axial strain per step, with individual steps being followed by stress relaxation down to strain rates ~10-9 s-1. Both bischofite and carnallite reached near steady state creep behaviour within each constant strain rate step. Carnallite was found to be 4-5 times stronger than bischofite. For bischofite as well as carnallite, we observed that during stress relaxation, the conventional power law stress exponent n changed from ~5 at 10-5 to ~1 at 10-9 s-1. The absolute strength of both materials remained higher if the relaxation started at a higher stress, i.e. at a faster rate. We interpret this as indicating a difference in microstructure at the initiation of the relaxation, notably a smaller grain size related to dynamical recrystallization during the constant strain rate step. The data thus suggest that there is gradual change in mechanism with decreasing strain rate, from grain size insensitive dislocation creep to grain size sensitive (pressure solution) creep. The mixed bischofite-carnallite-halite salt rock did not approach steady state

  15. Emergent nanoscale fluctuations in high rock-salt PbTe

    NASA Astrophysics Data System (ADS)

    Billinge, Simon

    2013-03-01

    Lead Telluride is one of the most promising thermoelectric materials in the temperature range just above room temperature. It is a narrow band gap semiconductor with a high Seebeck coefficient and a low thermal conductivity. It is structurally much simpler than many other leading candidates for high performance thermoelectrics being a binary rock-salt, isostructural to NaCl. The thermoelectric figure of merit, ZT, can be markedly improved by alloying with various other elements by forming quenched nanostructures. The undoped endmember, PbTe, does not have any such quenched nanostructure, yet has a rather low intrinsic thermal conductivity. There are also a number of interesting and non-canonical behaviors that it exhibits, such as an increasing measured band-gap with increasing temperature, exactly opposite to what is normally seen due to Fermi smearing of the band edge, and an unexpected non-monotonicity of the band gap in the series PbTe - PbSe - PbS. The material is on the surface simple, but hides some interesting complexity. We have investigated in detail the PbTe endmember using x-ray and neutron diffraction and neutron inelastic scattering. To our surprise, using the atomic pair distribution function (PDF) analysis of neutron powder diffraction data we found that an interesting and non-trivial local structure that appears on warming. with the Pb atoms moving off the high-symmetry rock-salt positions towards neighboring Te ions. No evidence for the off-centering of the Pb atoms is seen at low temperature. The crossover from the locally undistorted to the locally distorted state occurs on warming between 100 K and 250 K. This unexpected emergence of local symmetry broken distortions from an undistorted ground-state we have called emphanisis, from the Greek for appearing from nothing. We have also investigated the lattice dynamics of the system to search for a dynamical signature of this behavior and extended the studies to doped systems and I will also

  16. Accelerator Measurments of the Askaryan Effect in Rock Salt: A Roadmap Toward Teraton Underground Neutrino Detectors

    SciTech Connect

    Gorham, P.

    2004-12-15

    We report on further SLAC measurements of the Askaryan effect: coherent radio emission from charge asymmetry in electromagnetic cascades. We used synthetic rock salt as the dielectric medium, with cascades produced by GeV bremsstrahlung photons at the Final Focus Test Beam. We extend our prior discovery measurements to a wider range of parameter space and explore the effect in a dielectric medium of great potential interest to large scale ultra-high energy neutrino detectors: rock salt (halite), which occurs naturally in high purity formations containing in many cases hundreds of cubic km of water-equivalent mass. We observed strong coherent pulsed radio emission over a frequency band from 0.2-15 GHz. A grid of embedded dual-polarization antennas was used to confirm the high degree of linear polarization and track the change of direction of the electric-field vector with azimuth around the shower. Coherence was observed over 4 orders of magnitude of shower energy. The frequency dependence of the radiation was tested over two orders of magnitude of UHF and microwave frequencies. We have also made the first observations of coherent transition radiation from the Askaryan charge excess, and the result agrees well with theoretical predictions. Based on these results we have performed detailed and conservative simulation of a realistic GZK neutrino telescope array within a salt-dome, and we find it capable of detecting 10 or more contained events per year from even the most conservative GZK neutrino models.

  17. Accelerator measurements of the Askaryan effect in rock salt: A roadmap toward teraton underground neutrino detectors

    SciTech Connect

    Gorham, P.W.; Guillian, E.; Milincic, R.; Miocinovic, P.; Saltzberg, D.; Williams, D.; Field, R.C.; Walz, D.

    2005-07-15

    We report on further SLAC measurements of the Askaryan effect: coherent radio emission from charge asymmetry in electromagnetic cascades. We used synthetic rock salt as the dielectric medium, with cascades produced by GeV bremsstrahlung photons at the Final Focus Test Beam. We extend our prior discovery measurements to a wider range of parameter space and explore the effect in a dielectric medium of great potential interest to large-scale ultra-high-energy neutrino detectors: rock salt (halite), which occurs naturally in high purity formations containing in many cases hundreds of km{sup 3} of water-equivalent mass. We observed strong coherent pulsed radio emission over a frequency band from 0.2-15 GHz. A grid of embedded dual-polarization antennas was used to confirm the high degree of linear polarization and track the change of direction of the electric-field vector with azimuth around the shower. Coherence was observed over 4 orders of magnitude of shower energy. The frequency dependence of the radiation was tested over 2 orders of magnitude of UHF and microwave frequencies. We have also made the first observations of coherent transition radiation from the Askaryan charge excess, and the result agrees well with theoretical predictions. Based on these results we have performed a detailed and conservative simulation of a realistic GZK neutrino telescope array within a salt dome, and we find it capable of detecting 10 or more contained events per year from even the most conservative GZK neutrino models.

  18. Cyclic Loading Effects on the Creep and Dilation of Salt Rock

    NASA Astrophysics Data System (ADS)

    Roberts, Lance A.; Buchholz, Stuart A.; Mellegard, Kirby D.; Düsterloh, Uwe

    2015-11-01

    The Solution Mining Research Institute (SMRI) has embarked on inquiries into the effect cyclic loading might have on salt. This interest stems from the concept of using salt caverns as a storage medium for renewable energy projects such as compressed air energy storage where daily pressure cycles in the cavern are conceivable as opposed to the seasonal cycles that are typical for natural gas storage projects. RESPEC and the Institut für Aufbereitung und Deponietechnik at Clausthal University of Technology jointly executed a rock mechanics laboratory study using both facilities for performing triaxial cyclic loading creep tests on rock salt recovered from the Avery Island Mine in Louisiana, USA. The cyclic triaxial creep tests were performed under various load paths including compression, extension, and compression/extension. The tests were performed under both dilative and nondilative stress regimes. The cyclic compression creep data were compared to static creep tests performed under similar conditions to assess the effect of cycling of the applied stress. Furthermore, the cyclic compression tests were compared to a numerically simulated static creep test at the same stress and temperature conditions to determine if the creep behavior was similar under cyclic loading.

  19. Steady-State Creep of Rock Salt: Improved Approaches for Lab Determination and Modelling

    NASA Astrophysics Data System (ADS)

    Günther, R.-M.; Salzer, K.; Popp, T.; Lüdeling, C.

    2015-11-01

    Actual problems in geotechnical design, e.g., of underground openings for radioactive waste repositories or high-pressure gas storages, require sophisticated constitutive models and consistent parameters for rock salt that facilitate reliable prognosis of stress-dependent deformation and associated damage. Predictions have to comprise the active mining phase with open excavations as well as the long-term development of the backfilled mine or repository. While convergence-induced damage occurs mostly in the vicinity of openings, the long-term behaviour of the backfilled system is dominated by the damage-free steady-state creep. However, because in experiments the time necessary to reach truly stationary creep rates can range from few days to years, depending mainly on temperature and stress, an innovative but simple creep testing approach is suggested to obtain more reliable results: A series of multi-step tests with loading and unloading cycles allows a more reliable estimate of stationary creep rate in a reasonable time. For modelling, we use the advanced strain-hardening approach of Günther-Salzer, which comprehensively describes all relevant deformation properties of rock salt such as creep and damage-induced rock failure within the scope of an unified creep ansatz. The capability of the combination of improved creep testing procedures and accompanied modelling is demonstrated by recalculating multi-step creep tests at different loading and temperature conditions. Thus reliable extrapolations relevant to in-situ creep rates (10^{-9} to 10^{-13} s^{-1}) become possible.

  20. Sulfidation of rock-salt-type transition metal oxide nanoparticles as an example of a solid state reaction in colloidal nanoparticles.

    PubMed

    Chen, Chih-Jung; Chiang, Ray-Kuang

    2011-01-28

    The sulfidation of colloidal rock-salt-type MO (M = Fe, Mn and Co) nanocrystals was performed in organic solvents using dissolved elemental sulfur at moderate temperatures. The vacancy defects in these rock-salt-type structures clearly promote complete oxide-sulfide conversion. The conversion products were hollow metal sulfide (pyrrhotite (Fe(1-x)S), Co(1-x)S and α-MnS) nanoparticles. These conversions by sulfidation proceed rapidly, making difficult the isolation of intermediates. The sulfidation intermediates, when the supply of sulfur was insufficient, had interesting structures, in which the metal oxide cores were surrounded by metal sulfide shells or had surfaces that were decorated with metal sulfide islands. Based on the above results, a mechanism of surface nucleation, shell formation, and void formation by diffusion processes is proposed. PMID:21140007

  1. An ultra-high-energy-neutrino detector using rock salt and ice as detection media for radar method

    SciTech Connect

    Chiba, Masami; Kamijo, Toshio; Tanikawa, Takahiro; Yabuki, Fumiaki; Yasuda, Osamu; Akiyama, Hidetoshi; Chikashige, Yuichi; Kon, Tadashi; Shimizu, Yutaka; Utsumi, Michiaki; Fujii, Masatoshi

    2012-11-12

    We had found radio-wave-reflection effect in rock salt for detection of an ultra-high energy neutrino (UHE{nu}) which is generated in GZK processes in the universe. When an UHE{nu} interacts with rock salt or ice as a detection medium, the energy converts to a thermal energy. Consequently, a temperature gives rise along an UHE{nu} shower at the interaction location. The permittivity arises with respect to the temperature at ionization processes of the UHE{nu} shower which is composed of hadronic and electromagnetic multiplication processes. The irregularity of the refractive index in the medium for radio wave rises to a reflection. The reflection effect with a long attenuation length of radio wave in rock salt and ice would yield a new method to detect UHE{nu}. They could be used for detection media in which the UHE{nu} interacts with. We could find a huge amount of rock salt or ice over 50 Gt in a natural rock salt formation or Antarctic ice sheet. Radio wave transmitted into the medium generated by a radar system could be reflected by the irregularity of the refractive index at the shower. Receiving the reflected radio wave yields information about the UHE{nu}.

  2. Energy-polarization behaviors of AA'BB'O6 perovskites with double rock-salt order

    NASA Astrophysics Data System (ADS)

    Roy, Anindya; Vanderbilt, David

    2010-03-01

    Using first-principles methods, we study the energy-polarization relation of double perovskites AA'BB'O6 where atoms in both A and B sites are arranged in rock-salt order. The high-symmetry structure in this case is the tetrahedral F43m space group. If a ferroelectric instability occurs, the energy-vs.-polarization landscape E(P) will tend to have minima for P along tetrahedral directions leading to a rhombohedral space group R3m, with two different values of spontaneous polarization and associated energy along opposite body-diagonal directions; or along Cartesian directions, leading to orthorhombic space group Imm2. We search for polar soft modes at the γ point of the high-symmetry F43m structure and analyze its eigenvectors to identify ferroelectric instabilities, which we find in CaBaTiZrO6, KCaZrNbO6 and PbSnTiZrO6. The results of the first-principle calculations are modeled with a Landau-Devonshire expansion that is truncated at either 4th or 5th order in P, and its predictions are found to agree favorably with our calculation. The 5th-order calculation improves the agreement further except in PSTZ. Recently, synthesis of SrCaTiMnO6 in rock-salt order has been reported.footnotetextJ.L Blok, G. Rijnders and D.H.A. Blank, private communication. Unfortunately, preliminary results do not seem to indicate any polarized structure.

  3. The complete genome of a viable archaeum isolated from 123-million-year-old rock salt.

    PubMed

    Jaakkola, Salla T; Pfeiffer, Friedhelm; Ravantti, Janne J; Guo, Qinggong; Liu, Ying; Chen, Xiangdong; Ma, Hongling; Yang, Chunhe; Oksanen, Hanna M; Bamford, Dennis H

    2016-02-01

    Live microbes have been isolated from rock salt up to Permian age. Only obligatory cellular functions can be performed in halite-buried cells. Consequently, their genomic sequences are likely to remain virtually unchanged. However, the available sequence information from these organisms is scarce and consists of mainly ribosomal 16S sequences. Here, live archaea were isolated from early Cretaceous (∼ 123 million years old) halite from the depth of 2000 m in Qianjiang Depression, Hubei Province, China. The sample was radiologically dated and subjected to rigorous surface sterilization before microbe isolation. The isolates represented a single novel species of Halobacterium, for which we suggest the name Halobacterium hubeiense, type strain Hbt. hubeiense JI20-1. The species was closely related to a Permian (225-280 million years old) isolate, Halobacterium noricense, originating from Alpine rock salt. This study is the first one to publish the complete genome of an organism originating from surface-sterilized ancient halite. In the future, genomic data from halite-buried microbes can become a key factor in understanding the mechanisms by which these organisms are able to survive in harsh conditions deep underground or possibly on other celestial bodies. PMID:26628271

  4. [Structure and Activity of Fungal Lipases in Bile Salt Solutions].

    PubMed

    Bogdanova, L R; Bakirova, D R; Valiullina, Yu A; Idiyatullin, B Z; Faizullin, D A; Zueva, O S; Zuev, Yu F

    2016-01-01

    The changes in structure and catalytic properties of fungal lipases (Candida rugosa, Rhizomucor miehei, Mucor javanicus) were investigated in micellar solutions of bile salts that differ in hydrophilic-lypophilic balance and reaction medium properties. The methods of circular dichroism and tryptophan fluorescence were applied to estimate the changes in peptide structure within complexes with bile salt micelles. Bile salts do not exert a significant influence on the structure of the enzymes under study: in Rh. miehei and M. javanicus lipases the alpha helix content slightly decreased, the influence of bile salts on the C. rugosa structure was not revealed. Despite negligible structural modifications in the enzymes, in bile salt solutions a considerable change in their catalytic properties was observed: an abrupt decrease in catalytic effectiveness. Substrate-bile salts micelles complex formation was demonstrated by the NMR self-diffusion method. The model of a regulation of fungal lipase activity was proposed. PMID:27192825

  5. A New Elasto-Viscoplastic Damage Model Combined with the Generalized Hoek-Brown Failure Criterion for Bedded Rock Salt and its Application

    NASA Astrophysics Data System (ADS)

    Ma, Lin-jian; Liu, Xin-yu; Fang, Qin; Xu, Hong-fa; Xia, Hui-min; Li, Er-bing; Yang, Shi-gang; Li, Wen-pei

    2013-01-01

    According to the requirement of the West-East Gas Transmission Project in China, the solution-mined cavities located in the Jintan bedded salt formation of Jiangsu province will be utilized for natural gas storage. This task is more challenging than conventional salt dome cavern construction and operation due to the heterogeneous bedding layers of the bedded salt formation. A three-dimensional creep damage constitutive model combined with the generalized Hoek-Brown model is exclusively formulated and validated with a series of strength and creep tests for the bedded rock salt. The viscoplastic model, which takes the coupled creep damage and the failure behavior under various stress states into account, enables both the three creep phases and the deformation induced by vicious damage and plastic flow to be calculated. A further geomechanical analysis of the rapid gas withdrawal for the thin-bedded salt cavern was performed by implementing the proposed model in the finite difference software FLAC3D. The volume convergence, the damage and failure propagation of the cavern, as well as the strain rate of the salt around the cavern, were evaluated and discussed in detail. Finally, based on the simulation study, a 7-MPa minimum internal pressure is suggested to ensure the structural stability of the Jintan bedded salt cavern. The results obtained from these investigations provide the necessary input for the design and construction of the cavern project.

  6. Comparison and Tensorial Formulation of Inelastic Constitutive Models of Salt Rock Behaviour and Efficient Numerical Implementatio

    NASA Astrophysics Data System (ADS)

    Nagel, T.; Böttcher, N.; Görke, U. J.; Kolditz, O.

    2014-12-01

    The design process of geotechnical installations includes the application of numerical simulation tools for safety assessment, dimensioning and long term effectiveness estimations. Underground salt caverns can be used for the storage of natural gas, hydrogen, oil, waste or compressed air. For their design one has to take into account fluctuating internal pressures due to different levels of filling, the stresses imposed by the surrounding rock mass, irregular geometries and possibly heterogeneous material properties [3] in order to estimate long term cavern convergence as well as locally critical wall stresses. Constitutive models applied to rock salt are usually viscoplastic in nature and most often based on a Burgers-type rheological model extended by non-linear viscosity functions and/or plastic friction elements. Besides plastic dilatation, healing and damage are sometimes accounted for as well [2]. The scales of the geotechnical system to be simulated and the laboratory tests from which material parameters are determined are vastly different. The most common material testing modalities to determine material parameters in geoengineering are the uniaxial and the triaxial compression tests. Some constitutive formulations in widespread use are formulated based on equivalent rather than tensorial quantities valid under these specific test conditions and are subsequently applied to heterogeneous underground systems and complex 3D load cases. We show here that this procedure is inappropriate and can lead to erroneous results. We further propose alternative formulations of the constitutive models in question that restore their validity under arbitrary loading conditions. For an efficient numerical simulation, the discussed constitutive models are integrated locally with a Newton-Raphson algorithm that directly provides the algorithmically consistent tangent matrix for the global Newton iteration of the displacement based finite element formulation. Finally, the finite

  7. Deformation above mobile substrates, salt rheology and spatial distribution of salt structures: A 3D seismic study of the Permian southern North Sea

    NASA Astrophysics Data System (ADS)

    Hernandez, Karina; Mitchell, Neil; Huuse, Mads

    2016-04-01

    At ~255 Ma, cycles of evaporation of seawater led to deposition of evaporites including halite (rock salt) in the North Sea Basin. After later burial by denser sediments, the salt beds rose as pillows and diapirs. Assuming mobilization is due to Rayleigh-Taylor gravitational instability of heavy fluid (sediments) overlying light fluid (salts), theory suggests that the spacing between diapirs should be proportional to the original thickness of the salt layer. For example, a description of the theory in Turcotte and Schubert (1982) predicts structure wavelength to be 2.6 times the salt thickness. Previous research has explored mobilization of salt deposits assuming they have uniform rheology. However, this is not justified as halite rheology varies with temperature, grain size and pore brine content. Furthermore, evaporitic sequences contain various minerals besides halite (e.g., anhydrite, gypsum), which have different rheological properties. 3D seismic and well data reveal the internal structure of salt beds. The data have allowed characterization of structure wavelengths and salt thickness, so that the impact of internal composition and other properties on halokinetic behaviour can be assessed.

  8. The structure of the Zechstein 3 stringer in the northern Netherlands, and its implications for salt kinematics and rheology

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Urai, Janos; Li, Shiyuan; Schmatz, Joyce; Biehl, Bianca; Reuning, Lars; Raith, Alexander; Abe, Steffen; van Gent, Heijn; de Keijzer, Martin; Kukla, Peter

    2016-04-01

    The thick, late Permian Zechstein evaporites in the northern Netherlands are exceptionally well imaged in extensive 3D seismic and well datasets. The prominent seismic reflections of the thick, anhydrite-rich Zechstein 3 stringer, which is encased in thick layers of rock salt, provide a basin-scale view of the 3D internal structure of the Zechstein salt. The interpretation of the Z3 stringer was used as a strain marker for the different intra-salt deformation styles and salt flows. Furthermore, models of competing rheologies (pressure solution vs. dislocation creep, Newtonian vs. Power law) were tested in numerical simulations of the gravitational sinking of Z3 stringer fragments through the salt over geologic time in the Tertiary. The results show that several structural stringer styles can be linked to regional variation in salt kinematics. These mainly comprise local early syn-depositional gravitational movement, passive salt diapirism by differential loading in the Triassic, and reactive diapirism during contractions starting in the Cretaceous. The thickness and deformation degree of the individual salt layers thereby played a major role in the development of regionally distinctive styles of intra-salt structures, which can be linked to breaking and fold patterns in the stringer. When differential stresses in the salt relaxed across large parts of the northern Netherlands in the Tertiary, stringer fragments physically isolated in the salt did not significantly sink through the salt. The salt surrounding the fragments can not have deformed by Newtonian solution-precipitation creep, because the fragments would have sunk to base salt. Considering also results from geomechanical modelling and analysis of Zechstein salt samples, we conclude that this behaviour can only be explained by strong changes in salt rheology to non-Newtonian.

  9. Authigenic K-feldspar in salt rock (Haselgebirge Formation, Eastern Alps)

    NASA Astrophysics Data System (ADS)

    Leitner, Christoph

    2015-04-01

    The crystallisation of authigenic quartz under low temperature, saline conditions is well known (Grimm, 1962). Also the growth of low temperature authigenic feldspar in sediments is a long known phenomenon (Kastner & Siever, 1979; Sandler et al., 2004). In this study we intend to show that halite (NaCl) is a major catalyser for authigenic mineral growth. During late Permian (c. 255-250 Ma), when the later Eastern Alps were located around north of the equator, the evaporites of the Haselgebirge Formation were deposited (Piller et al., 2004). The Haselgebirge Fm. consists in salt mines of a two-component tectonite of c. 50 % halite and 50 % sedimentary clastic and other evaporite rocks (Spötl 1998). Most of the clastic rocks are mud- to siltstones ("mudrock"). During this study, we investigated rare sandstones embedded in salt rock form four Alpine salt mines. Around 40 polished thin sections were prepared by dry grinding for thin section analysis and scanning electron microscopy. The sandstones consist mainly of quartz, K-feldspar, rock fragments, micas, accessory minerals and halite in the pore space. They are fine grained and well sorted. Mudrock clasts in sandstone were observed locally, and also coal was observed repeatedly. Asymmetric ripples were found only in the dimension of millimeters to centimeters. Euhedral halite crystals in pores indicate an early presence of halite. During early diagenesis, authigenic minerals crystallized in the following chronological order. (1) Where carbonate (mainly magnesite) occurred, it first filled the pore space. Plant remains were impregnated with carbonate. (2) Halite precipitated between the detritic sandstone grains. Carbonate grains can be completely embedded in halite. (3) K-feldspar and quartz grains usually expose a detritic core and a later grown euhedral inclusion free rim. Euhedral rims of K-feldspar often also enclose a halite core. K-feldspar replaced the pre-existing halite along former grain boundaries of

  10. Thermal properties of rock salt and quartz monzonite to 573{sup 0}K and 50-MPa confining pressure

    SciTech Connect

    Durham, W.B.; Abey, A.E.

    1981-03-18

    Measurements of thermal conductivity, thermal diffusivity, and thermal linear expansion have been made on two rock types, a rock salt and a quartz monzonite, at temperatures from 300 to 573{sup 0}K and confining pressures from 10 to 50 MPa. The samples were taken from deep rock formations under consideration as possible sites for a nuclear waste repository - the rock salt from a domal salt formation at Avery Island, Louisiana, and the quartz monzonite from the Climax Stock, Nevada Test Site, Nevada. The testing temperature and pressures are meant to bracket conditions expected in the repository. In both rock types, the thermal properties show a strong dependence upon temperature and a weak or non-dependence upon confining pressure. Thermal conductivity and diffusivity both decrease with increasing temperature in approximately linear fashion for samples which have not been previously heated. At 50 MPa in both rocks this decrease closely matches the measured or expected intrinsic (crack-free) behavior of the material. Preliminary indications from the quartz monzonite suggest that conductivity and diffusivity at low pressure and temperature may decrease as a result of heat treatment above 400{sup 0}K.

  11. Rupture dimensions and rupture processes of fluid-induced microcracks in salt rock

    NASA Astrophysics Data System (ADS)

    Dahm, T.

    2001-08-01

    We developed and applied a simple empirical Green function method to study induced microcracks observed during hydraulic fracturing experiments in salt rock. Either unidirectional ruptures on rectangular faults or allround ruptures on elliptical faults are tested to explain the observed directivity effects in body-wave amplitude spectra. Mostly, the rectangular rupture model and horizontal fault planes are favored. The average rupture lengths are between 15 and 27 mm, the average rupture durations between 14 and 26 μs. Small average rupture velocities of 30% of the S-wave velocity of the rock are indicated. The dispersive low-frequency coda-waves present in the data look similar to coda-waves observed during other hydraulic fracturing experiments and to long-period events from some volcanoes, which have been explained by the resonance of a fluid-filled crack. The radiation pattern of first motion amplitudes of most events is dominated by a dip-slip double-couple indicating slip on horizontal or vertical planes. We cannot distinguish whether the observed low-frequency coda-waves are influenced by a source effect or by a possible sensor-borehole coupling. However, a simple method using Gauss filter at different center frequencies and relocation is tested to analyze the low-frequency coda-waves in terms of source models.

  12. Stress corrosion of ASTM Grade-2 and Grade-12 titanium in simulated rock salt brines at 83/sup 0/C

    SciTech Connect

    Jain, H.; Ahn, T.M.; Soo, P.

    1983-01-01

    Slow-strain-rate tests have been conducted on Grade-2 and Grade-12 titanium in simulated rock salt brines at 83/sup 0/C. Although neither metal shows stress corrosion cracking, total elongation and reduction in area show some decrease. Optical and SEM results are discussed to elucidate the fracture mechanism.

  13. A1 and A2, two novel haloarchaeal isolates from bore cores of ancient Alpine rock salt deposits

    NASA Astrophysics Data System (ADS)

    Gruber, C.; Pfaffenhuemer, M.; Weidler, G.; Radax, C.; Stan-Lotter, H.

    2003-04-01

    Previously several novel halophilic archaea, for instance Haloccocus salifodinae BIp and Halococcus dombrowskii, were isolated from Permo-Triassic rock salt (age 200 - 250 million years) in our laboratory. By using molecular methods we found evidence for the presence of numerous additional haloarchaeal taxa. We investigated freshly drilled salt cores from a depth of about 600 m below surface in the salt mine of Altaussee, Austria, which were dissolved immediately in sterile water. After plating the dissolved salts on high salt nutrient agar, we were able to isolate, following incubation for 3 months, two red pigmented colonies, which were designated A1 and A2 and cultivated for further investigation. A1 and A2 showed the same antibiotic susceptibility as Halobacterium salinarum DSM 3754 and Halobacterium sp. NRC-1, which were cultivated from surface waters. Additionally, the cell morphology of the new isolates was highly similar to both reference strains. According to 16S rRNA gene sequences, whole cell protein patterns following SDS polyacrylamide gel electrophoresis, and restriction digestion patterns of their DNA following pulsed field gel electrophoresis, the isolates A1 and A2 could not be distinguished. 16S rRNA gene sequences indicated that the closest relative of strains A1 and A2 was Halobacterium salinarum DSM 3754 (sequence similarity 97,1%). Our results suggest that the isolates A1 and A2 might constitute a new haloarchaeal species, entrapped in ancient rock salt.

  14. Laboratory Evaluation of Damage Criteria and Creep Parameters of Tioga Dolomite and Rock Salt from Cavern Well No. 1

    SciTech Connect

    LEE, MOO Y.; EHGARTNER, BRIAN L.

    2002-04-01

    A suite of laboratory triaxial compression and triaxial steady-state creep tests provide quasi-static elastic constants and damage criteria for bedded rock salt and dolomite extracted from Cavern Well No.1 of the Tioga field in northern Pennsylvania. The elastic constants, quasi-static damage criteria, and creep parameters of host rocks provides information for evaluating a proposed cavern field for gas storage near Tioga, Pennsylvania. The Young's modulus of the dolomite was determined to be 6.4 ({+-}1.0) x 10{sup 6} psi, with a Poisson's ratio of 0.26 ({+-}0.04). The elastic Young's modulus was obtained from the slope of the unloading-reloading portion of the stress-strain plots as 7.8 ({+-}0.9) x 10{sup 6} psi. The damage criterion of the dolomite based on the peak load was determined to be J{sub 2}{sup 0.5} (psi) = 3113 + 0.34 I{sub 1} (psi) where I{sub 1} and J{sub 2} are first and second invariants respectively. Using the dilation limit as a threshold level for damage, the damage criterion was conservatively estimated as J{sub 2}{sup 0.5} (psi) = 2614 + 0.30 I{sub 1} (psi). The Young's modulus of the rock salt, which will host the storage cavern, was determined to be 2.4 ({+-}0.65) x 10{sup 6} psi, with a Poisson's ratio of 0.24 ({+-}0.07). The elastic Young's modulus was determined to be 5.0 ({+-}0.46) x 10{sup 6} psi. Unlike the dolomite specimens under triaxial compression, rock salt specimens did not show shear failure with peak axial load. Instead, most specimens showed distinct dilatancy as an indication of internal damage. Based on dilation limit, the damage criterion for the rock salt was estimated as J{sub 2}{sup 0.5} (psi) = 704 + 0.17 I{sub 1} (psi). In order to determine the time dependent deformation of the rock salt, we conducted five triaxial creep tests. The creep deformation of the Tioga rock salt was modeled based on the following three-parameter power law as {var_epsilon}{sub s} = 1.2 x 10{sup -17} {sigma}{sup 4.75} exp(-6161/T), where {var

  15. Optical and electron transport properties of rock-salt Sc1-xAlxN

    NASA Astrophysics Data System (ADS)

    Deng, Ruopeng; Zheng, P. Y.; Gall, D.

    2015-07-01

    Epitaxial single-crystal Sc1-xAlxN ternary alloy layers deposited by magnetron co-sputtering on MgO(001) substrates at 950 °C exhibit a solid solution rock-salt phase for x = 0-0.2 without decomposition. Optical absorption indicates a linear increase in the optical gap from 2.51 eV for ScN to 3.05 eV for Sc0.8Al0.2N and, after correction due to the Moss-Burstein shift, a direct X point interband transition energy Eg(X) = 2.15 + 2.75 x (eV). Correspondingly, the direct transition at the zone center increases with Al concentration according to Eg(Γ) = 3.80 + 1.45 x (eV), as determined from a feature in the reflection spectra. All layers are degenerate n-type semiconductors with a room temperature mobility that decreases from 22 to 6.7 to 0.83 cm2/V s as x increases from 0 to 0.11 to 0.20. The corresponding carrier densities are 9.2 × 1020, 7.9 × 1020, and 0.95 × 1020 cm-3 as determined from Hall measurements and consistent with optical free carrier absorption below photon energies of 1 eV. Temperature dependent transport measurements indicate metallic conduction for ScN, but weak localization that leads to a resistivity minimum at 85 and 210 K for x = 0.051 and 0.15, respectively, and a negative temperature coefficient over the entire measured 4-300 K range for Sc0.8Al0.2N. The decreasing mobility is attributed to alloy scattering at randomly distributed Al atoms on cation sites, which also cause the weak localization. The carrier density is primarily due to unintentional F doping from the Sc target and decreases strongly for x > 0.15, which is attributed to trapping in defect states due to the deterioration of the crystalline quality, as evidenced by the x-ray diffraction peak width that exhibits a minimum of 0.14° for x = 0.11 but increases to 0.49° for x = 0.20. This is consistent with asymmetric x-ray diffraction analyses, indicating a relaxed lattice constant that decreases from 4.511 ± 0.005 to 4.411 ± 0.004 Å for x = 0-0.2, and a biaxial in

  16. In situ measurements of rock salt permeability changes due to nearby excavation

    SciTech Connect

    Stormont, J.C. ); Howard, C.L. ); Daemen, J.J.K. . Mackay School of Mines)

    1991-07-01

    The Small-Scale Mine-By was an in situ experiment to measure changes in brine and gas permeability of rock salt as a result of nearby excavation. A series of small-volume pressurized brine- and gas-filled test intervals were established 8 m beneath the floor of Room L1 in the WIPP underground. The test intervals were isolated in the bottom of the 4.8-cm diameter monitoring boreholes with inflatable rubber packers, and are initially pressurized to about 2 MPa. Both brine- and gas-filled test intervals were located 1.25, 1.5, 2, 3, and 4 r from the center of a planned large-diameter hole, where r is the radius of the large-diameter hole. Prior to the drilling of the large-diameter borehole, the responses of both the brine- and gas-filled test intervals were consistent with the formation modeled as a very low permeability, low porosity porous medium with a significant pore (brine) pressure and no measurable gas permeability. The drilling of the mine-by borehole created a zone of dilated, partially saturated rock out to about 1.5 r. The formation pressure increases from near zero at 1.5 r to the pre-excavation value at 4 r. Injection tests reveal a gradient of brine permeabilities from 5 {times} 10{sup {minus}18} m{sup 2} at 1.25 r to about the pre-excavation value (10{sup {minus}21} m{sup 2}) by 3 r. Gas-injection tests reveal measurable gas permeability is limited to within 1.5 r. 17 refs., 24 figs., 6 tabs.

  17. First-principles study of rock-salt AgCl xBr 1-x alloys

    NASA Astrophysics Data System (ADS)

    Amrani, B.; El Haj Hassan, F.; Zoaeter, M.

    2007-06-01

    We present first-principles calculations of the structural, electronic and thermodynamic properties of rock-salt AgCl xBr 1-x alloys by application of the full potential linearized augmented plane wave (FP-LAPW) method. We use both Perdew-Burke-Ernzerhof and Engel-Vosko generalized gradient approximations of the exchange-correlation energy that are based on the optimization of total energy and corresponding potential, respectively. The effect of composition on lattice constants, bulk modulus, cohesive energy, bond ionicity, band gap and effective mass was investigated. These parameters were found to depend nonlinearly on alloy composition x, except the lattice parameter, which follows Vegard's law. The microscopic origins of the gap bowing were explained by using the approach of Zunger and co-workers; we have concluded that the band gap energy bowing was mainly caused by the chemical charge-transfer effect, while the volume deformation and the structural relaxation contribute to the gap bowing parameter at smaller magnitude. On the other hand, the thermodynamic stability of AgCl xBr 1-x was investigated by calculating the excess enthalpy of mixing Δ Hm as well as the phase diagram.

  18. Electrochemical characteristics of Li 2- xVTiO 4 rock salt phase in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Dominko, R.; Garrido, C. Vidal-Abraca; Bele, M.; Kuezma, M.; Arcon, I.; Gaberscek, M.

    Li 2- xVTiO 4/C sample with a disordered rock salt structure was successfully prepared by annealing at a temperature of 850 °C. The electrochemical oxidation in the first cycle occurs at voltages above 4 V vs. metallic lithium, while the shapes of the electrochemical curves in consequent reduction-oxidation processes show a monotonous change of the potential between the selected cut-off voltages. A linear combination fit of individual XANES spectra was used for the determination of the oxidation states of as prepared sample and intermediate states during oxidation and reduction. In the as-prepared sample, vanadium was found to be in the average oxidation state of V 3.5+ and was additionally oxidized to V 3.8+ by the electrochemical charging. During the discharge process, the vanadium oxidation state was reduced to V 3.0+. In situ X-ray diffraction patterns and EXAFS analysis suggest good structural stability during oxidation and reduction, which is also reflected in the cycling stability if batteries were cycled in the voltage window between 2.0 V and 4.4 V. Extension of the lower cut-off voltage to 1.0 V doubles the capacity retention with the improved capacity stability if compared with several high capacity vanadium based materials.

  19. The use of thick-walled hollow cylinder creep tests for evaluating flow criteria for rock salt

    SciTech Connect

    Morgan, H.S.; Wawersik, W.R.

    1990-01-01

    Finite element simulations of two laboratory creep tests on thick-walled hollow cylinders of rock salt are evaluated to determine if such bench-scale experiments can be used to establish applicability of either von Mises or Tresca stress measures and associated flow conditions. In the tests, the cylinders were loaded axially and pressurized both internally and externally to produce stress fields similar to those found around underground excavations in rock salt. Several different loading stages were used in each test. The simulations show that for each of two creep models studied, quite different deformations of the cylinders are predicted with the Mises and Tresca flow criteria, especially if friction between the cylinders and axial loading platens is ignored. When friction is included in the simulations, the differences in deformation are changed but are sill clearly distinguishable. 10 refs., 10 figs.

  20. Ion chromatography to detect salts in stone structures and to assess salt removal methods

    NASA Astrophysics Data System (ADS)

    Alvarez de Buergo, M.; Lopez-Arce, P.; Fort, R.

    2012-04-01

    Stone - and in general all materials- from built heritage is very often damaged by salt crystallisation processes. Such processes usually derive into a loss of material compactness, as salts - given specific conditions and parameters- crystallize inside the material pores, exerting a pressure against the material pore walls higher than what they can resist - similar to the effect of liquid water when converts to solid water or ice-, thus breaking and disrupting the material by generating fissures and increasing the pore volume ratio, loosing its initial cohesion. When these deterioration processes take place inside a structure, salts - from different sources: material itself, restoration materials, from the ground, etc.- may come up to the stone surface - either temporarily or in permanently-, from beneath it, as efflorescences, depending mainly on the microclimatic conditions of the environment and the salts source. Efflorescences can be analysed and their nature identified (e.g. by means of X ray diffraction, in which the mineralogical composition of the salt is obtained), which can be, general, of aid not only for restoration but for preventive conservation measures. But what we do not know a priori when only characterising salt compounds- is the extent of the damage due to the presence of salts inside a structure (sub- and cryptoefflorescences). In this work we present a procedure in which the depth of the salt content can be measured, and its nature identified, based on the use of the ion chromatography technique. This technique allows identifying the existing ions in a specific sample, both anions and cations. The procedure consists of drilling (with a drilling core ranging from 5 to 8 mm in diameter, therefore causing the minimum damage to the material) in a same point at different depths from the surface and several depths from the bottom. The samples obtained are analysed and the ion content determined, qualitative and quantitatively. By means of a

  1. Mechanical modeling of the growth of salt structures

    SciTech Connect

    Alfaro, R.A.M.

    1993-05-01

    A 2D numerical model for studying the morphology and history of salt structures by way of computer simulations is presented. The model is based on conservation laws for physical systems, a fluid marker equation to keep track of the salt/sediments interface, and two constitutive laws for rocksalt. When buoyancy alone is considered, the fluid-assisted diffusion model predicts evolution of salt structures 2.5 times faster than the power-law creep model. Both rheological laws predict strain rates of the order of 4.0 {times} 10{sup {minus}15}s{sup {minus}1} for similar structural maturity level of salt structures. Equivalent stresses and viscosities predicted by the fluid-assisted diffusion law are 10{sup 2} times smaller than those predicted by the power-law creep rheology. Use of East Texas Basin sedimentation rates and power-law creep rheology indicate that differential loading is an effective mechanism to induce perturbations that amplify and evolve to mature salt structures, similar to those observed under natural geological conditions.

  2. Modeling of the T S D E Heater Test to Investigate Crushed Salt Reconsolidation and Rock Salt Creep for the Underground Disposal of High-Level Nuclear Waste

    NASA Astrophysics Data System (ADS)

    Blanco Martin, L.; Rutqvist, J.; Birkholzer, J. T.; Wolters, R.; Lux, K. H.

    2014-12-01

    Rock salt is a potential medium for the underground disposal of nuclear waste because it has several assets, in particular its water and gas tightness in the undisturbed state, its ability to heal induced fractures and its high thermal conductivity as compared to other shallow-crustal rocks. In addition, the run-of-mine, granular salt, may be used to backfill the mined open spaces. We present simulation results associated with coupled thermal, hydraulic and mechanical processes in the TSDE (Thermal Simulation for Drift Emplacement) experiment, conducted in the Asse salt mine in Germany [1]. During this unique test, conceived to simulate reference repository conditions for spent nuclear fuel, a significant amount of data (temperature, stress changes and displacements, among others) was measured at 20 cross-sections, distributed in two drifts in which a total of six electrical heaters were emplaced. The drifts were subsequently backfilled with crushed salt. This test has been modeled in three-dimensions, using two sequential simulators for flow (mass and heat) and geomechanics, TOUGH-FLAC and FLAC-TOUGH [2]. These simulators have recently been updated to accommodate large strains and time-dependent rheology. The numerical predictions obtained by the two simulators are compared within the framework of an international benchmark exercise, and also with experimental data. Subsequently, a re-calibration of some parameters has been performed. Modeling coupled processes in saliniferous media for nuclear waste disposal is a novel approach, and in this study it has led to the determination of some creep parameters that are very difficult to assess at the laboratory-scale because they require extremely low strain rates. Moreover, the results from the benchmark are very satisfactory and validate the capabilities of the two simulators used to study coupled thermal, mechanical and hydraulic (multi-component, multi-phase) processes relative to the underground disposal of high

  3. Heavy Metal Contamination and Salt Efflorescence Associated With Decorative Landscaping Rocks, Las Vegas, Nevada: The Need for Regulations

    NASA Astrophysics Data System (ADS)

    Mrozek, S. A.; Buck, B. J.; Brock, A. L.

    2004-12-01

    Las Vegas, Nevada is one of the fastest growing cities in the United States. Faced with water restrictions, decorative rock xeroscaping has become a very popular form of landscaping. Currently, there are no regulations controlling the geochemistry of the decorative rocks that can be used for these purposes. In this study, we examined three sites containing two different decorative rock products. The landscaping rocks, underlying soil, and surface salt crusts were analyzed to determine their mineralogy and chemistry. Methods of analysis include scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP), thin section analysis, and laser particle size analysis (LPSA). Preliminary results indicate the presence of halite (NaCl), bloedite (Na2Mg(SO4)2 4H2O), a hydrated magnesium sulfate, and possibly copper sulfate and copper chloride mineral phases in the surface salt crusts. Both copper minerals are regarded as hazardous substances by the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA); these agencies have established minimum exposure limits for human contact with these substances. Copper sulfate and copper chloride are not naturally occurring minerals in the soils of the Las Vegas Valley, and analyses indicate that their formation may be attributed to the mineralogy of the decorative landscaping rocks. Further testing is needed to characterize this potential health hazard; however the preliminary results of this study demonstrate the need for regulations controlling the geochemistry of decorative rocks used for urban landscaping.

  4. Structural evolution of the Namakdan salt diapir in the Zagros fold-thrust belt: The Persian Gulf, Iran

    NASA Astrophysics Data System (ADS)

    Shahpasandzadeh, Majid; Hashemifar, Ghasem; Shafiei Bafti, Amir

    2016-04-01

    Intersalt and host roch structures of the the Namakdan diapir were studied and compared with available 14C and OSL dated sediments to determine the structural evolution and uplift pattern of the diapir. The Namakdan salt diapir is situated on Qeshm Island in the east of the Zagros fold-thrust belt of Iran, north of the Persian Gulf. This nearly circular diapir with ~ 7 km diameter penetrates the crest of Salkh anticline and is embedded by steep-dip bedding of the Miocene Mishan and Aghajari Formations, which demonstrates the concentric internal structure of the diapir. The intraformational unconformities of country rocks were developed due to the Zagros shortening and salt diapirism, which demonstrate their syn-tectonic sedimentation. In addition, the dip of these unconfromities and also bedding of the country rocks decrease upward. The Namakdan diapir is partly covered by gypsum/anhydrite residuals, dolomite, marine limestone, and tilted marine terraces. The salt belong to the Hormuz Complex, consisted of predominantly halite, gypsum, anhydrite, dolomite, shale, sandstone, and volcanic-volanoclastic blocks, which was deposited in the Late Proterozoic-Middle Cambrian evaporitic rift basins. The Hormuz Complex is not only the cause of many salt diapir oil/gas fields but is also considered to have been a major source rock for generation of younger reservoirs. Thus, the salt diapirs of the Zagros play an important role in generation of the oil/gas reservoirs in this strategic area, so determination of structural style and evolution of the salt diapirs are vital in oil/gas exploration and development. The upright folds are developed in the salt beds due to upward movement and minor extrusion of the salt rocks due to its low viscosity. The dip of country rock beds increase toward to the diapir rim, so that the beds shows a vertical and even overturned attitude in vicinity of the diapir. Differential uplift pattern of the diapir was deduced in rim-to-center profiles by

  5. Rocks.

    ERIC Educational Resources Information Center

    Lee, Alice

    This science unit is designed for limited- and non-English speaking students in a Chinese bilingual education program. The unit covers rock material, classification, characteristics of types of rocks, and rock cycles. It is written in Chinese and simple English. At the end of the unit there is a list of main terms in both English and Chinese, and…

  6. Permeability of natural rock salt from the Waste Isolation Pilot Plant (WIPP) during damage evolution and healing

    SciTech Connect

    Pfeifle, T.W.

    1998-06-01

    The US Department of Energy has developed the Waste Isolation Pilot Plant (WIPP) in the bedded salt of southeastern New Mexico to demonstrate the safe disposal of radioactive transuranic wastes. Four vertical shafts provide access to the underground workings located at a depth of about 660 meters. These shafts connect the underground facility to the surface and potentially provide communication between lithologic units, so they will be sealed to limit both the release of hazardous waste from and fluid flow into the repository. The seal design must consider the potential for fluid flow through a disturbed rock zone (DRZ) that develops in the salt near the shafts. The DRZ, which forms initially during excavation and then evolves with time, is expected to have higher permeability than the native salt. The closure of the shaft openings (i.e., through salt creep) will compress the seals, thereby inducing a compressive back-stress on the DRZ. This back-stress is expected to arrest the evolution of the DRZ, and with time will promote healing of damage. This paper presents laboratory data from tertiary creep and hydrostatic compression tests designed to characterize damage evolution and healing in WIPP salt. Healing is quantified in terms of permanent reduction in permeability, and the data are used to estimate healing times based on considerations of first-order kinetics.

  7. Internal structure of mushroom-shaped salt diapirs

    SciTech Connect

    Not Available

    1989-01-01

    This book focuses on the dynamics and kinematics of salt diapirs with crestal bulbs shaped like a mushroom, one of the most complex types of diapirs, as interpreted by experimental modeling and from naturally occurring examples. Direct, practical applications of this research include use in the evaluation of salt domes as repositories for radioactive waste, in the exploration and production of salt, potash, and sulfur, and in the search for subtle hydrocarbon traps. The authors conducted 8 centrifuge experiments, which produced more than 100 model diapirs. These experiments were dynamically scaled to U.S. Gulf Coast salt domes, but the qualitative results are also relevant to salt diapirs in other provinces and to granitoid diapirs penetrating metamorphic crust. The centrifuged domes grew under overburdens of constant thickness or under aggrading and prograding overburdens, a new experimental approach. Results indicate that external mushroom structure results from toroidal circulation of buoyant source and immediate cover having similar effective viscosities, whereas internal structure is produced by toroidal circulation confined within the diapir. The internal diapir structure elucidates the mechanics of emplacement and indicates whether an external mushroom shape can be expected and sought by further exploration.

  8. Using three dimensional structural simulations to study the interactions of multiple excavations in salt

    SciTech Connect

    Hoffman, E.L.; Ehgartner, B.L.

    1998-02-01

    Three-dimensional quasistatic finite element codes are being used at Sandia National Laboratories to simulate the interactions of multiple large room and pillar mines in rock salt. The calculations presented in this paper are of a salt dome which contains multiple closely-spaced room and pillar mines. One of the mines was used as an oil storage facility, supported by the US DOE under the auspices of the Strategic Petroleum Reserve (SPR) program. The facility has recently been decommissioned due to the discovery of geotechnical instabilities. The model, validated by field observations, has resulted in a better understanding of the mechanisms which can threaten the stability of an underground excavation, as well as the structural interactions of multiple excavations. Although these calculations were performed in the specific interest of the SPR, the results should be of interest to mine designers concerned with the interactions of multiple mines excavated in a common formation.

  9. Framboidal Structures in Earth Rocks and in Astromaterials

    NASA Technical Reports Server (NTRS)

    Astafieva, M. M.; Rozanov, Alexei Y.; Hoover, Richard B.

    2003-01-01

    Framboidal structures are common both in Earth rocks and in meteorites - carbonaceous chondrites. The main methods of formation of these structures are discussed. The role of biologic factors in formation of framboids is evaluated. Comparison of crystal forms comprising framboids formed in laboratory conditions and in nature is provided. On the basis of investigations of framboidal structures the proposition that pyritoidal form of crystals is typical for the formation of biogenic framboidal structures.

  10. Air-Liquid Interfaces: II. Water Structure and Salts

    NASA Astrophysics Data System (ADS)

    Allen, Heather; Gopalakrishnan, Sandhya; Ma, Gang; Liu, Dingfang; Levering, Lori

    2004-03-01

    Aqueous salt solutions were investigated using scanning sum frequency generation (SFG), a highly surface-selective spectroscopy, and ATR-IR and Raman spectroscopies. Water surface structure was investigated for NaF, NaCl, NaBr and NaI aqueous solutions and surface data indicate a significantly disturbed hydrogen bonding environment from that of neat water. The spectra strongly suggest the presence of bromide and iodide anions in the interfacial region in addition to an increase in interfacial depth; yet the surfaces of the sodium fluoride and chloride salt solutions do not show evidence of surface water perturbation. Ammonium chloride and sulfate, and sodium sulfate aqueous solutions were also investigated. Surface water structure varied considerably between the three salt solutions. Electric double layer effects are indicated.

  11. A petrographical and geochemical study of quartzose nodules, country rocks, and dike rocks from the Upheaval Dome structure, Utah

    USGS Publications Warehouse

    Koeberl, C.; Plescia, J.B.; Hayward, C.L.; Reimold, W.U.

    1999-01-01

    Upheaval Dome, in Canyonlands National Park, Utah, USA, is a unique structure on the Colorado Plateau. It has earlier been interpreted as an impact structure or as a pinched-off salt diapir. Some subrounded quartzose fragments were found in a ring depression near the eastern margin of the structure and, based on vesicularity and apparent flow structure, the fragments were interpreted by early researchers as 'impactites.' Our petrographic studies show no indication of a high-temperature history and are in agreement with a slow, low-temperature formation of the quartz nodules. Compositionally, the lag deposit samples are almost pure SiO2. They show no chemical similarity to any of the possible target rocks (e.g., Navajo Sandstone), from which they should have formed by melting if they were impactites. Instead, the samples have relatively high contents of elements that indicate fluid interaction (e.g., hydrothermal growth), such as As, Sb, Ba, and U, and show positive Ce anomalies. Thus, we interpret the 'lag deposit samples' as normal low-temperature (hydrothermally-grown?) quartz that show no indication of being impact-derived. In addition, a petrographic and geochemical analysis of a series of dike samples yielded no evidence for shock metamorphism or a meteoritic component.

  12. Microfabrics and 3D grain shape of Gorleben rock salt: Constraints on deformation mechanisms and paleodifferential stress

    NASA Astrophysics Data System (ADS)

    Thiemeyer, Nicolas; Zulauf, Gernold; Mertineit, Michael; Linckens, Jolien; Pusch, Maximilian; Hammer, Jörg

    2016-04-01

    The Permian Knäuel- and Streifensalz formations (z2HS1 and z2HS2) are main constituents of the Gorleben salt dome (Northern Germany) and show different amounts and distributions of anhydrite. The reconstruction of 3D halite grain shape ellipsoids reveals small grain size (3.4 ± 0.6 mm) and heterogeneous grain shapes in both formations, the latter attributed to the polyphase deformation of the rock salt during diapirism. The halite microfabrics of both formations indicate that strain-induced grain boundary migration was active during deformation. Crystal plastic deformation of halite is further documented by lattice bending, subgrain formation and minor subgrain rotation. Evidence for pressure solution of halite has not been found, but cannot be excluded because of the small grain size, the lack of LPO and the low differential stress (1.1-1.3 MPa) as deduced from subgrain-size piezometry. Anhydrite has been deformed in the brittle-ductile regime by solution precipitation creep, minor dislocation creep and brittle boudinage. No continuous anhydrite layers are preserved, and halite has acted as a sealing matrix embedding the disrupted anhydrite fragments prohibiting any potential migration pathways for fluids. Thus, anhydrite should not have a negative effect on the barrier properties of the Gorleben rock salts investigated in this study.

  13. Depleted δ13C Values in Salt Dome Cap Rock Organic Matter and Implications for Microbial Metabolism and Fixation

    NASA Astrophysics Data System (ADS)

    Loyd, S. J.; Lu, L.; Caesar, K. H.; Kyle, R.

    2015-12-01

    Salt domes occur throughout the Gulf Coast Region USA and are often associated with trapped hydrocarbons. These salt domes can be capped by sulfate and carbonate minerals that result from complex digenetic interactions in the subsurface. The specific natures of these interactions are poorly understood, in particular the role of microbes in facilitating mineralization and element cycling. Carbon isotope compositions of cap rock calcites (δ13Ccarb) are highly variable and range from near neutral to less than -40‰ (VPDB) indicative of methane-sourced carbon. These low values and the common coexistence of elemental sulfur and metal sulfides have spurred hypotheses invoking microbial sulfate reduction as driving carbonate mineral authigenesis. Here, we present new organic carbon isotope (δ13Corg) data that, similar to δ13Ccarb, exhibit depletions below -30 to -25‰. These δ13Corg values are lower than local liquid hydrocarbons and "normal" marine organic matter reflecting either microbial fixation of methane-sourced carbon or microbial fractionation from liquid hydrocarbon sources. The combined carbon isotope data (δ13Ccarb and δ13Corg) indicate that methane likely plays an important role in microbial cycling in salt domes. The δ13Corg values are similar to those of anaerobic oxidation of methane (AOM) related communities from methane-sulfate controlled marine sediments. Ultimately, salt dome environments may share some important characteristics with AOM systems.

  14. Observations regarding the stability of bentonite backfill in a high-level waste (HLW) repository in rock salt

    SciTech Connect

    Krumhansl, J.L.

    1986-01-01

    Consideration of bentonite as a component of the engineered barrier system surrounding high-level nuclear waste (HLW) canisters in rock salt raised several questions regarding the stability of this clay. Dehydration studies pertinent to the period immediately following waste emplacement showed a partial loss in swelling ability, the extent of which depended on the composition of the rehydrating brine and increased with temperature from 150/sup 0/ to 320/sup 0/C. At a later date, hydrothermal reactions between brine and bentonite may occur as pressure in the repository rises and the backfill saturates with brine. In pure sodium chloride brines little change in the bentonite was observed after two months at 250/sup 0/C. In the same amount of time, brines rich in potassium formed mixed-layer, illite-smectite clays. Adding magnesium to the brine arrested mixed-layer clay formation; instead, a magnesium-enriched montmorillonite formed and the brine pH dropped. Radiation stability studies to 10/sup 10/ rads were conducted in both wet and dry environments, but caused no detectable alteration of the clay. In contrast, fluid-phase compositions changed significantly. Gamma irradiation of dry bentonite produced an oxygen-depleted atmosphere which was enriched in both hydrogen and carbon dioxide. Mixed bentonite-brine slurries produced copious amounts of both hydrogen and oxygen gas when irradiated. These irradiated slurries generally had posttest pH values between 4 and 6. Solutions made by exposing preirradiated salt and bentonite to unirradiated water, or brine, had pH values between 6 and 8.5 and, in the case of salt solutions, were highly oxidizing. Although more research is needed for a complete performance assessment, it appears that such backfills may prove useful in a variety of rock-salt environments.

  15. Structural analysis of Precambrian rocks at the Hot Dry Rock Site at Fenton Hill, New Mexico

    SciTech Connect

    Burns, K.L.; Potter, R.M.

    1995-01-01

    The subcrop of basement rock at Fenton HIll comprises Precambrian gneiss, schist, amphibolite, pegmatite, and granitoids with affinities in metamorphic and structural history to surface outcrops in the Tusas and Picuris Ranges. Televiewer measurements of structures were analyzed by taking advantage of the spatial continuity of foliations. Folds in the foliation are predominantly conical forms due to interference between structures formed in F2 and F3 tectonic events. Field observations of outcrops in the Picuris Range show that the fractures are predominantly an X-T network controlled by the lithological layering, and statistical evidence indicates that this layer-controlled network persists to depth at Fenton Hill.

  16. Using Aluminum Foil to Record Structures in Sedimentary Rock.

    ERIC Educational Resources Information Center

    Metz, Robert

    1982-01-01

    Aluminum foil can be used to make impressions of structures preserved in sedimentary rock. The impressions can be projected onto a screen, photographed, or a Plaster of Paris model can be made from them. Impressions of ripple marks, mudcracks, and raindrop impressions are provided in photographs illustrating the technique. (Author/JN)

  17. Salt movements and faulting of the overburden - can numerical modeling predict the fault patterns above salt structures?

    NASA Astrophysics Data System (ADS)

    Clausen, O. R.; Egholm, D. L.; Wesenberg, R.

    2012-04-01

    Salt deformation has been the topic of numerous studies through the 20th century and up until present because of the close relation between commercial hydrocarbons and salt structure provinces of the world (Hudec & Jackson, 2007). The fault distribution in sediments above salt structures influences among other things the productivity due to the segmentation of the reservoir (Stewart 2006). 3D seismic data above salt structures can map such fault patterns in great detail and studies have shown that a variety of fault patterns exists. Yet, most patterns fall between two end members: concentric and radiating fault patterns. Here we use a modified version of the numerical spring-slider model introduced by Malthe-Sørenssen et al.(1998a) for simulating the emergence of small scale faults and fractures above a rising salt structure. The three-dimensional spring-slider model enables us to control the rheology of the deforming overburden, the mechanical coupling between the overburden and the underlying salt, as well as the kinematics of the moving salt structure. In this presentation, we demonstrate how the horizontal component on the salt motion influences the fracture patterns within the overburden. The modeling shows that purely vertical movement of the salt introduces a mesh of concentric normal faults in the overburden, and that the frequency of radiating faults increases with the amount of lateral movements across the salt-overburden interface. The two end-member fault patterns (concentric vs. radiating) can thus be linked to two different styles of salt movement: i) the vertical rising of a salt indenter and ii) the inflation of a 'salt-balloon' beneath the deformed strata. The results are in accordance with published analogue and theoretical models, as well as natural systems, and the model may - when used appropriately - provide new insight into how the internal dynamics of the salt in a structure controls the generation of fault patterns above the structure. The

  18. Measurements of radio propagation in rock salt for the detection of high-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Connolly, Amy; Goodhue, Abigail; Miki, Christian; Nichol, Ryan; Saltzberg, David

    2009-02-01

    We present measurements of the transmission of radio/microwave pulses through salt in the Cote Blanche salt mine operated by the North American Salt Company in St. Mary Parish, Louisiana. These results are from data taken in the southwestern region of the 1500 ft (457 m) deep level of the mine on our third and most recent visit to the mine. We transmitted and received a fast, high-power, broadband pulse from within three vertical boreholes that were drilled to depths of 100 ft (30 m) and 200 ft below the 1500 ft level using three different pairs of dipole antennas whose bandwidths span 125-900 MHz. By measuring the relative strength of the received pulses between boreholes with separations of 50 and 169 m, we deduce the attenuation of the signal attributed to the salt medium. We fit the frequency dependence of the attenuation to a power law and find the best fit field attenuation lengths to be 93±7m at 150 MHz, 63±3m at 300 MHz, and 36±2m at 800 MHz. This is the most precise measurement of radio attenuation in a natural salt formation to date. We assess the implications of this measurement for a future neutrino detector in salt.

  19. Measurement of radio wave reflection due to temperature rising from rock salt and ice irradiated by an electron beam for an ultra-high-energy neutrino detector

    SciTech Connect

    Tanikawa, Takahiro; Chiba, Masami; Kamijo, Toshio; Yabuki, Fumiaki; Yasuda, Osamu; Akiyama, Hidetoshi; Chikashige, Yuichi; Kon, Tadashi; Shimizu, Yutaka; Utsumi, Michiaki; Fujii, Masatoshi

    2012-11-12

    An ultra-high-energy neutrino (UHE{nu}) gives temperature rise along the hadronic and electromagnetic shower when it enters into rock salt or ice. Permittivities of them arise with respect the temperatures at ionization processes of the UHE{nu} shower. It is expected by Fresnel's formula that radio wave reflects at the irregularity of the permittivity in the medium. We had found the radio wave reflection effect in rock salt. The reflection effect and long attenuation length of radio wave in rock salt and ice would yield a new UHE{nu} detection method. An experiment for ice was performed to study the reflection effect. A coaxial tube was filled with rock salt powder or ice. Open end of the coaxial tube was irradiated by a 2 MeV electron beam. Radio wave of 435 MHz was introduced to the coaxial tube. We measured the reflection wave from the open end. We found the radio wave reflection effect due to electron beam irradiation in ice as well as in rock salt.

  20. Use of nanotomographic images for structure analysis of carbonate rocks

    SciTech Connect

    Nagata, Rodrigo; Appoloni, Carlos Roberto

    2014-11-11

    Carbonate rocks store more than 50% of world's petroleum. These rocks' structures are highly complex and vary depending on many factors regarding their formation, e.g., lithification and diagenesis. In order to perform an effective extraction of petroleum it is necessary to know petrophysical parameters, such as total porosity, pore size and permeability of the reservoir rocks. Carbonate rocks usually have a range of pore sizes that goes from nanometers to meters or even dozen of meters. The nanopores and micropores might play an important role in the pores connectivity of carbonate rocks. X-ray computed tomography (CT) has been widely used to analyze petrophysical parameters in recent years. This technique has the capability to generate 2D images of the samples' inner structure and also allows the 3D reconstruction of the actual analyzed volume. CT is a powerful technique, but its results depend on the spatial resolution of the generated image. Spatial resolution is a measurement parameter that indicates the smallest object that can be detected. There are great difficulties to generate images with nanoscale resolution (nanotomographic images). In this work three carbonate rocks, one dolomite and two limestones (that will be called limestone A and limestone B) were analyzed by nanotomography. The measurements were performed with the SkyScan2011 nanotomograph, operated at 60 kV and 200 μA to measure the dolomite sample and 40 kV and 200 μA to measure the limestone samples. Each sample was measured with a given spatial resolution (270 nm for the dolomite sample, 360 nm for limestone A and 450 nm for limestone B). The achieved results for total porosity were: 3.09 % for dolomite, 0.65% for limestone A and 3.74% for limestone B. This paper reports the difficulties to acquire nanotomographic images and further analysis about the samples' pore sizes.

  1. Effect of high salt concentrations on water structure

    NASA Astrophysics Data System (ADS)

    Leberman, R.; Soper, A. K.

    1995-11-01

    THE characteristic tetrahedral structure of water is known to be disrupted by changes in pressure and temperature1-3. It has been suggested that ions in solution may have a similar perturbing effect4,5. Here we use neutron diffraction to compare the effects of applied pressure and high salt concentrations on the hydrogen-bonded network of water. We find that the ions induce a change in structure equivalent to the application of high pressures, and that the size of the effect is ion-specific. Ionic concentrations of a few moles per litre have equivalent pressures that can exceed a thousand atmospheres. We propose that these changes may be understood in terms of the partial molar volume of the ions, relative to those of water molecules. The equivalent induced pressure of a particular ion species is correlated with its efficacy in precipitating, or salting-out, proteins from solution6.

  2. The Significance of Interfacial Water Structure in Soluble Salt Flotation Systems.

    PubMed

    Hancer, M.; Celik, M. S.; Miller, J. D.

    2001-03-01

    Flotation of soluble salts with dodecyl amine hydrochloride (DAH) and sodium dodecyl sulfate (SDS) collectors has demonstrated that the interfacial water structure and hydration states of soluble salt surfaces together with the precipitation tendency of the corresponding collector salts are of considerable importance in explaining their flotation behavior. In particular, the high concentration of ions in these soluble salt brines and their hydration appear to modify the bulk and interfacial structure of water as revealed by contact angle measurements and this effect is shown to be an important feature in the flotation chemistry of soluble salt minerals including alkali halide and alkali oxyanion salts. Depending on characteristic chemical features (salt type), the salt can serve either as a structure maker, in which intermolecular hydrogen bonding between water molecules is facilitated, or as a structure breaker, in which intermolecular hydrogen bonding between water molecules is disrupted. For structure making salts the brine completely wets the salt surface and no contact angle can be measured. For structure breaking salts the brine does not completely wet the salt surface and a finite contact angle is measured. In this regard it has been found that soluble salt flotation either with the cationic DAH or anionic SDS collector is possible only if the salt is a structure breaker. Copyright 2001 Academic Press. PMID:11237454

  3. Uniaxial creep as a control on mercury intrusion capillary pressure in consolidating rock salt

    SciTech Connect

    Dewers, Thomas; Heath, Jason E.; Leigh, Christi D.

    2015-09-01

    The nature of geologic disposal of nuclear waste in salt formations requires validated and verified two - phase flow models of transport of brine and gas through intact, damaged, and consolidating crushed salt. Such models exist in oth er realms of subsurface engineering for other lithologic classes (oil and gas, carbon sequestration etc. for clastics and carbonates) but have never been experimentally validated and parameterized for salt repository scenarios or performance assessment. Mo dels for waste release scenarios in salt back - fill require phenomenological expressions for capillary pressure and relative permeability that are expected to change with degree of consolidation, and require experimental measurement to parameterize and vali date. This report describes a preliminary assessment of the influence of consolidation (i.e. volume strain or porosity) on capillary entry pressure in two phase systems using mercury injection capillary pressure (MICP). This is to both determine the potent ial usefulness of the mercury intrusion porosimetry method, but also to enable a better experimental design for these tests. Salt consolidation experiments are performed using novel titanium oedometers, or uniaxial compression cells often used in soil mech anics, using sieved run - of - mine salt from the Waste Isolation Pilot Plant (WIPP) as starting material. Twelve tests are performed with various starting amounts of brine pore saturation, with axial stresses up to 6.2 MPa (%7E900 psi) and temperatures to 90 o C. This corresponds to UFD Work Package 15SN08180211 milestone "FY:15 Transport Properties of Run - of - Mine Salt Backfill - Unconsolidated to Consolidated". Samples exposed to uniaxial compression undergo time - dependent consolidation, or creep, to various deg rees. Creep volume strain - time relations obey simple log - time behavior through the range of porosities (%7E50 to 2% as measured); creep strain rate increases with temperature and applied stress as

  4. Impurities in rock-salt: consequences for the temperature increases at the disposal of high-level nuclear waste. [Kainite, Kieserite

    SciTech Connect

    van den Broek, W.M.G.T.

    1982-06-01

    In part A the thermal properties of halite and the other materials occurring in rock-salt (the 'impurities') are collected. Except for sylvite (the specific heat of this salt is about 70% of the value for halite) all specific heats are larger than the specific heat of halite. The consequences for the temperature increases at the disposal of high-level nuclear waste in rock-salt are discussed for impurity concentrations of 1, 5, 10 and 15%. If the presence and distribution of the impurities are not taken into account, then - under the most unfavorable conditions - extra temperature increases of about 3% per cent impurity may occur. If, however, the geological composition and its geometry for the disposal region are known, the temperature increases can be calculated more accurately: they may or may not differ from those for pure halite. In part B the measurement of the thermal conductivity for four salts (kainite, kieserite, carnallite, and polyhalite) is described.

  5. Prehistoric Rock Structures of the Idaho National Laboratory

    SciTech Connect

    Brenda R Pace

    2007-04-01

    Over the past 13,500 years, human populations have lived in and productively utilized the natural resources offered by the cold desert environment of the northeastern Snake River Plain in eastern Idaho. Within an overall framework of hunting and gathering, groups relied on an intimate familiarity with the natural world and developed a variety of technologies to extract the resources that they needed to survive. Useful items were abundant and found everywhere on the landscape. Even the basaltic terrain and the rocks, themselves, were put to productive use. This paper presents a preliminary classification scheme for rock structures built on the Idaho National Laboratory landscape by prehistoric aboriginal populations, including discussions of the overall architecture of the structures, associated artifact assemblages, and topographic placement. Adopting an ecological perspective, the paper concludes with a discussion of the possible functions of these unique resources for the desert populations that once called the INL home.

  6. Structural Color of Rock Dove’s Neck Feather

    NASA Astrophysics Data System (ADS)

    Nakamura, Eri; Yoshioka, Shinya; Kinoshita, Shuichi

    2008-12-01

    It is well known that some kinds of animal have surprisingly brilliant colors showing beautiful iridescence. These colors are called structural colors, and are thought to originate from optical interference caused by periodic microstructures that have sizes comparable with the wavelength of light. However, much larger structural modifications can also play an important role in the coloration mechanism. In this paper, we show through careful optical and structural investigations that the structural color of the neck feather of rock dove, Columba livia, has a very comprehensive mechanism: the thin-layer optical interference phenomenon fundamentally produces the iridescence, while the layer structure is accompanied by various kinds of larger-size structural modifications that control the angular range of the reflection. Further, it is found that the granules containing melanin pigment exist in a localized manner to effectively enhance the contrast of the color caused by optical interference.

  7. AMS fabric and structural record along a strain gradient in an extrusive salt diapir (Kuh-e-Namak, Dashti, Iran)

    NASA Astrophysics Data System (ADS)

    Zavada, Prokop; Schulmann, Karel; Lexa, Ondrej; Machek, Matej; Roxerova, Zuzana; Kusbach, Vladimir

    2016-04-01

    The AMS record and the halite fabrics on meso- and micro-scale were studied in detail on a well exposed salt extrusive body in Iran. In the Kuh-e-Namak (Dashti) mountain salt diapir, the deformation structures in colored salt are displayed along longitudinal profiles across the dome and two glaciers that extend from the NE and SW edge of the dome. The profiles from the dome to the frontal parts of the glaciers reveal a continuous strain gradient associated with transposition of the domal salt fabrics by axial fold cleavage development during flow of rock salt over the ridges in the channel. The extruded salt belongs to the Hormuz sequence of Neo-Proterozoic to Early Cambrian age. From central dome towards especially the northern namakier, structural record revealed zonation from; 1) gravitational collapse related recumbent isoclinal folds in the dome, 2) flat normal shears at the edge of the dome, 3) collapsed vertical layering into flat lying transpositional fabric at the toe of the dome, 4) penetrative fold cleavage transposition of earlier fabrics above the topographical ridge in the base of the flow, locally displaying strong transversal constrictional fabrics, 5) banded mylonites with isoclinal rootless folds in subhorizontally banded frontal and marginal domain of the glacier. The AMS fabric in the rock salt is generated primarily by hematite dispersed in the recrystallized halite. The AMS exhibits three main types of fabric symmetry from clustered all directions (K1,K2,K3, orthogonal fabric) to clustered K1 directions with girdle forming K2,K3 axes and clustered K3 directions with girdle of K1 and K2 directions. The AMS fabric clearly reflects the macroscopic fabric transpositions along the entire investigated strain gradient in the rock salt. Magnetic fabrics reveal continuous trends from bimodal to semi-girdle distribution of foliations in folded and cleavage present regions, to magnetic lineation clustering perpendicular to flow in completely refolded

  8. A coarse-grained model with implicit salt for RNAs: Predicting 3D structure, stability and salt effect

    SciTech Connect

    Shi, Ya-Zhou; Wang, Feng-Hua; Wu, Yuan-Yan; Tan, Zhi-Jie

    2014-09-14

    To bridge the gap between the sequences and 3-dimensional (3D) structures of RNAs, some computational models have been proposed for predicting RNA 3D structures. However, the existed models seldom consider the conditions departing from the room/body temperature and high salt (1M NaCl), and thus generally hardly predict the thermodynamics and salt effect. In this study, we propose a coarse-grained model with implicit salt for RNAs to predict 3D structures, stability, and salt effect. Combined with Monte Carlo simulated annealing algorithm and a coarse-grained force field, the model folds 46 tested RNAs (≤45 nt) including pseudoknots into their native-like structures from their sequences, with an overall mean RMSD of 3.5 Å and an overall minimum RMSD of 1.9 Å from the experimental structures. For 30 RNA hairpins, the present model also gives the reliable predictions for the stability and salt effect with the mean deviation ∼ 1.0 °C of melting temperatures, as compared with the extensive experimental data. In addition, the model could provide the ensemble of possible 3D structures for a short RNA at a given temperature/salt condition.

  9. Structural Interactions within Lithium Salt Solvates. Acyclic Carbonates and Esters

    SciTech Connect

    Afroz, Taliman; Seo, D. M.; Han, Sang D.; Boyle, Paul D.; Henderson, Wesley A.

    2015-03-06

    Solvate crystal structures serve as useful models for the molecular-level interactions within the diverse solvates present in liquid electrolytes. Although acyclic carbonate solvents are widely used for Li-ion battery electrolytes, only three solvate crystal structures with lithium salts are known for these and related solvents. The present work, therefore, reports six lithium salt solvate structures with dimethyl and diethyl carbonate: (DMC)2:LiPF6, (DMC)1:LiCF3SO3, (DMC)1/4:LiBF4, (DEC)2:LiClO4, (DEC)1:LiClO4 and (DEC)1:LiCF3SO3 and four with the structurally related methyl and ethyl acetate: (MA)2:LiClO4, (MA)1:LiBF4, (EA)1:LiClO4 and (EA)1:LiBF4.

  10. Preparation of Al-Si Master Alloy by Electrochemical Reduction of Volcanic Rock in Cryolite Molten Salt

    NASA Astrophysics Data System (ADS)

    Liu, Aimin; Shi, Zhongning; Xu, Junli; Hu, Xianwei; Gao, Bingliang; Wang, Zhaowen

    2016-06-01

    Volcanic rock found in the Longgang Volcano Group in Jilin Province of China has properties essentially similar to Apollo lunar soils and previously prepared lunar soil simulants, such as Johnson Space Center Lunar simulant and Minnesota Lunar simulant. In this study, an electrochemical method of preparation of Al-Si master alloy was investigated in 52.7 wt.%NaF-47.3 wt.%AlF3 melt adding 5 wt.% volcanic rock at 1233 K. The cathodic electrochemical process was studied by cyclic voltammetry, and the results showed that the cathodic reduction of Si(IV) is a two-step reversible diffusion-controlled reaction. Si(IV) is reduced to Si(II) by two electron transfers at -1.05 V versus platinum quasi-reference electrode in 52.7 wt.%NaF-47.3 wt.%AlF3 molten salt adding 5 wt.% volcanic rock, while the reduction peak at -1.18 V was the co-deposition of aluminum and silicon. In addition, the cathodic product obtained by galvanostatic electrolysis for 4 h was analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy and energy dispersive spectrometry. The results showed that the phase compositions of the products are Al, Si, Al5FeSi, and Al3.21Si0.47, while the components are 90.5 wt.% aluminum, 4.4 wt.% silicon, 1.9 wt.% iron, and 0.2 wt.% titanium.

  11. Preparation of Al-Si Master Alloy by Electrochemical Reduction of Volcanic Rock in Cryolite Molten Salt

    NASA Astrophysics Data System (ADS)

    Liu, Aimin; Shi, Zhongning; Xu, Junli; Hu, Xianwei; Gao, Bingliang; Wang, Zhaowen

    2016-04-01

    Volcanic rock found in the Longgang Volcano Group in Jilin Province of China has properties essentially similar to Apollo lunar soils and previously prepared lunar soil simulants, such as Johnson Space Center Lunar simulant and Minnesota Lunar simulant. In this study, an electrochemical method of preparation of Al-Si master alloy was investigated in 52.7 wt.%NaF-47.3 wt.%AlF3 melt adding 5 wt.% volcanic rock at 1233 K. The cathodic electrochemical process was studied by cyclic voltammetry, and the results showed that the cathodic reduction of Si(IV) is a two-step reversible diffusion-controlled reaction. Si(IV) is reduced to Si(II) by two electron transfers at -1.05 V versus platinum quasi-reference electrode in 52.7 wt.%NaF-47.3 wt.%AlF3 molten salt adding 5 wt.% volcanic rock, while the reduction peak at -1.18 V was the co-deposition of aluminum and silicon. In addition, the cathodic product obtained by galvanostatic electrolysis for 4 h was analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy and energy dispersive spectrometry. The results showed that the phase compositions of the products are Al, Si, Al5FeSi, and Al3.21Si0.47, while the components are 90.5 wt.% aluminum, 4.4 wt.% silicon, 1.9 wt.% iron, and 0.2 wt.% titanium.

  12. Composite grain size sensitive and grain size insensitive creep of bischofite, carnallite and mixed bischofite-carnallite-halite salt rock

    NASA Astrophysics Data System (ADS)

    Muhammad, Nawaz; de Bresser, Hans; Peach, Colin; Spiers, Chris

    2016-04-01

    Deformation experiments have been conducted on rock samples of the valuable magnesium and potassium salts bischofite and carnallite, and on mixed bischofite-carnallite-halite rocks. The samples have been machined from a natural core from the northern part of the Netherlands. Main aim was to produce constitutive flow laws that can be applied at the in situ conditions that hold in the undissolved wall rock of caverns resulting from solution mining. The experiments were triaxial compression tests carried out at true in situ conditions of 70° C temperature and 40 MPa confining pressure. A typical experiment consisted of a few steps at constant strain rate, in the range 10‑5 to 10‑8 s‑1, interrupted by periods of stress relaxation. During the constant strain rate part of the test, the sample was deformed until a steady (or near steady) state of stress was reached. This usually required about 2-4% of shortening. Then the piston was arrested and the stress on the sample was allowed to relax until the diminishing force on the sample reached the limits of the load cell resolution, usually at a strain rate in the order of 10‑9 s‑1. The duration of each relaxation step was a few days. Carnallite was found to be 4-5 times stronger than bischofite. The bischofite-carnallite-halite mixtures, at their turn, were stronger than carnallite, and hence substantially stronger than pure bischofite. For bischofite as well as carnallite, we observed that during stress relaxation, the stress exponent nof a conventional power law changed from ˜5 at strain rate 10‑5 s‑1 to ˜1 at 10‑9 s‑1. The absolute strength of both materials remained higher if relaxation started at a higher stress, i.e. at a faster strain rate. We interpret this as indicating a difference in microstructure at the initiation of the relaxation, notably a smaller grain size related to dynamical recrystallization during the constant strain rate step. The data thus suggest that there is a gradual change in

  13. Fluid distribution in grain boundaries of natural fine-grained rock salt deformed at low shear stress: implications for rheology and transport properties

    NASA Astrophysics Data System (ADS)

    Desbois, G.; Urai, J. L.; De Bresser, J. H. P.

    2012-04-01

    healing criterion of Van Noort et al. (2008). This suggests that PS creep is not active in our samples. Therefore, there is a disagreement with previous microstructural studies (Schléder and Urai, 2007; Desbois et al., 2010) of similar samples, which have shown active PS creep (and dislocation creep) in of salt glaciers. We discuss different explanations for this, which imply that both healing and reactivation of grain boundaries is important in salt glaciers, leading to heterogeneous distribution of deformation mechanisms and strain rates in both space and time. Desbois G., Zavada P., Schléder Z., Urai J.L., 2010. Deformation and recrystallization mechanisms in naturally deformed salt fountain: microstructural evidence for a switch in deformation mechanisms with increased availability of meteoric water and decreased grain size (Qum Kuh, central Iran). Journal of Structural Geology, 32 (4), 580-594. Schléder Z. and Urai J.L. (2007). Deformation and recrystallization mechanisms in mylonitic shear zones in naturally deformed extrusive Eocene-Oligocene rock salt from Eyvanekey plateau and Garmsar hills (central Iran). Journal of structural geology, 29: 241-255. Van Noort, R., Visser, H.J.M., Spiers, C.J., 2008. Influence of grain boundary structure on dissolution controlled pressure solution and retarding effects of grain boundary healing. J. Geophys. Res. 113.

  14. Crystal and molecular structure of perindopril erbumine salt

    NASA Astrophysics Data System (ADS)

    Remko, M.; Bojarska, J.; Ježko, P.; Sieroń, L.; Olczak, A.; Maniukiewicz, W.

    2011-06-01

    The crystal structure of perindopril (2S,3aS,7aS)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxopentan-2-yl]amino]propanoyl]-2,3,3a,4,5,6,7,7a-octahydroindole-2-carboxylic acid) erbumine salt C 23H 43N 3O 5, angiotensin-converting enzyme inhibitor, was determined from single-crystal X-ray diffraction data. The compound crystallizes in the triclinic, non-centrosymetric space group P1, with unit cell dimensions a = 6.575(3), b = 12.165(5), c = 16.988(8) Å and α = 97.153(4), β = 94.417(4), γ = 90.349(4)°, Z = 2. The structure was refined by full matrix least squares methods to R = 0.037. In the solid state ionized molecules of perindopril and erbumine are linked together forming a complex via O⋯HN + hydrogen bonds between the positively charged amino groups of the erbuminium cations and oxygen atoms of the perindopril carboxylate groups. Intermolecular N sbnd H⋯O and C sbnd H⋯O contacts seem to be effective in the stabilization of the structure, resulting in the formation of a three-dimensional network. The gas-phase structure of perindopril-erbumine complex was optimized by the HF/6-31G(d) and Becke3LYP/6-31G(d) methods. The conformational behavior of this salt in water was examined using the CPCM and Onsager models. In both the gas phase and water solution the perindopril erbumine will exist in prevailing triclinic form.

  15. Polar and Magnetic Layered A Site and Rock Salt B Site-Ordered NaLnFeWO6 (Ln = La, Nd) Perovskites

    SciTech Connect

    Tetuerto, Maria; Li, Mang-Rong; Ignatov, Alexander; Croft, Mark; Ramanujachary, Kandalam V.; Chi, Songxue; Hodges, Jason P; Dachraoui, W.; Hadermann, Joke; Thao Tran, T.; Shiv Halasyamani, P.; Grams, C.; Hemberger, J.; Greenblatt, M.

    2013-01-01

    We have expanded the double perovskite family of materials with the unusual combination of layered order in the A sublattice and rock salt order over the B sublattice to compounds NaLaFeWO6 and NaNdFeWO6. The materials have been synthesized and studied by powder X-ray diffraction, neutron diffraction, electron diffraction, magnetic measurements, X-ray absorption spectroscopy, dielectric measurements, and second harmonic generation. At room temperature, the crystal structures of both compounds can be defined in the noncentrosymmetric monoclinic P21 space group resulting from the combination of ordering both in the A and B sublattices, the distortion of the cell due to tilting of the octahedra, and the displacement of certain cations. The magnetic studies show that both compounds are ordered antiferromagnetically below TN 25 K for NaLaFeWO6 and at 21 K for NaNdFeWO6. The magnetic structure of NaNdFeWO6 has been solved with a propagation vector k = (1/2 0 1/2) as an antiferromagnetic arrangement of Fe and Nd moments. Although the samples are potential multiferroics, the dielectric measurements do not show a ferroelectric response.

  16. Resistance of halobacterial isolates from Permian rock salt to physico-chemical extremes, including heat and a simulated Martian atmosphere.

    NASA Astrophysics Data System (ADS)

    Leuko, S.; Weidler, G.; Radax, C.; Stan-Lotter, H.

    2003-04-01

    Extremely halophilic archaebacteria (halobacteria) are found today in hypersaline surface waters, such as the brines in solar salterns, or the Dead Sea. However, from Alpine rock salt of Permo-Triassic age several species of halobacteria were isolated during the last years (1, 2). Halobacteria are not known to produce spores or dormant forms; thus it remains enigmatic how they survived in the salt sediments. Extraterrestrial halite has been detected in meteorites from Mars and from the asteroids; in addition, the Jovian moon Europa is thought to contain a salty ocean. Therefore halobacteria would be useful model organisms when considering the search for extraterrestrial life. We are developing experimental protocols to evaluate the effects of physico-chemical stress factors on halobacteria, in particular present-day Martian conditions. But the effect of higher temperatures is also of interest, since Mars may have been warmer in the past, and the Alpine salt sediments are known to have experienced local temperature peaks. Cells of Halococcus dombrowskii (2) and, for comparison, of Halobacterium sp. NRC-1 were grown in complex medium, containing up to 4 M NaCl (2). Aliquots of cultures were kept at minus 70oC for several days, or freeze-dried in a lyophilizer, or incubated at temperatures of 50 to 80oC for 24 hours, respectively. In addition, exposure experiments of halobacterial cells in a liquid nitrogen cooled Martian simulation chamber were begun. Survival of cells was evaluated by determining colony-forming units and by examination of cellular morphology by fluorescence microscopy, following staining with the LIVE-DEAD kit. Results indicated that the LIVE-DEAD kit can be successfully used in the presence of 4 M NaCl, although it was developed for tests at low ionic strength. Data will be presented which show that Hc. dombrowskii survived deep freezing, temperatures of up to 80 oC and Martian atmospheric conditions generally better than Halobacterium sp. NRC-1

  17. A new structural model of the Pachitea Basin, Peru: Interaction of thick-skinned tectonics and salt detached thrusting

    NASA Astrophysics Data System (ADS)

    Witte, J.; Rebaza, J.; Westlund, D.; Stratton, M.; Alegria, C.

    2015-11-01

    We present four new structural transects, a new seismo-stratigraphic correlation, a refined structural model and new shortening rates for the Pachitea Basin (=PB), Peru. Our results are based on the integration and detailed interpretation of newly acquired industry seismic (2D, 2005 vintage), existing well data, existing and proprietary surface geology data and newly acquired aero magnetic data (2007 vintage). Our assessment confirms the presence of at least four distinct structural styles in the area, thick-skinned structures, thin-skinned detachment thrusting, salt-tectonics and localized strike-slip tectonics. Based on seismo-stratigraphic correlations we conclude that the oldest rocks carried to outcrop by the San Matias (=SM) thrust are of Jurassic age. We interpret the thin-skinned master detachment to be located in varying positions, directly below or above, autochtonous salt pillows. Timing assessment of the SM thrust sheet reveals that it has been active from at least ˜5 Ma to post-2 Ma, supporting regionally published timing data for this latitude. Positive topographic surface expressions indicate ongoing contraction along the mountain front of the Peruvian Eastern Cordillera (=EC). Across the PB we calculate between 2.6% and 5.5% for thick-skinned shortening and at least 25.5% for the thin-skinned shortening. For the SM thrust sheet we calculate a slip-rate of ˜1-1.6 mm/yr, which is in line with published slip rates on individual thrusts from around the world. Observations along the SM thrust system indicate that thin- and thick-skinned systems interact mechanically, and that they have been active intermittently. We conclude that the location of salt pillows as well as pre-existing or growing basement-involved structures helped trigger the SM thrust. Different types of salt bodies are present in the PB, autochtonous pillows, slightly thrusted pillows and allochtonous diapirs. Our results provide new insight into the structural interplay, particularly

  18. Geochemistry of Manson impact structure rocks - Target rocks, impact glasses, and microbreccias

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Hartung, Jack B.

    A representative set of samples of target rocks from the Manson Crater have been studied for the first time, and the results are reported. The target rocks show a wide range of composition for all elements. For most elements the range exhibited by the Manson Crater rocks (MCRs) plots within the range of the target rocks; however, a few elements are enriched in the MCR. The REE abundances are generally higher in the MCRs than the target rock; this may indicate a selective volatilization of low-REE target rocks such as carbonates and subsequent concentration of the REE-bearing accessory minerals in the MCRs. The composition of the MCRs indicate that those rocks comprise both Archean and post-Archean sedimentary sequences. All microbreccia samples and most glass samples have narrow range in the REE patterns. The chemistry of the MCRs is only marginally compatible with the composition of the newly discovered black impact glasses from the Haiti K/T boundary and is incompatible with the composition of the yellow glasses.

  19. The structure of performance of a sport rock climber.

    PubMed

    Magiera, Artur; Roczniok, Robert; Maszczyk, Adam; Czuba, Miłosz; Kantyka, Joanna; Kurek, Piotr

    2013-03-01

    This study is a contribution to the discussion about the structure of performance of sport rock climbers. Because of the complex and multifaceted nature of this sport, multivariate statistics were applied in the study. The subjects included thirty experienced sport climbers. Forty three variables were scrutinised, namely somatic characteristics, specific physical fitness, coordination abilities, aerobic and anaerobic power, technical and tactical skills, mental characteristics, as well as 2 variables describing the climber's performance in the OS (Max OS) and RP style (Max RP). The results show that for training effectiveness of advanced climbers to be thoroughly analysed and examined, tests assessing their physical, technical and mental characteristics are necessary. The three sets of variables used in this study explained the structure of performance similarly, but not identically (in 38, 33 and 25%, respectively). They were also complementary to around 30% of the variance. The overall performance capacity of a sport rock climber (Max OS and Max RP) was also evaluated in the study. The canonical weights of the dominant first canonical root were 0.554 and 0.512 for Max OS and Max RP, respectively. Despite the differences between the two styles of climbing, seven variables - the maximal relative strength of the fingers (canonical weight = 0.490), mental endurance (one of scales : The Formal Characteristics of Behaviour-Temperament Inventory (FCB-TI; Strelau and Zawadzki, 1995)) (-0.410), climbing technique (0.370), isometric endurance of the fingers (0.340), the number of errors in the complex reaction time test (-0.319), the ape index (-0.319) and oxygen uptake during arm work at the anaerobic threshold (0.254) were found to explain 77% of performance capacity common to the two styles. PMID:23717360

  20. Synthesis, single crystal structure and energy optimization of a multicomponent salt of imidazole and tetrabromoterepthalic acid

    SciTech Connect

    Singha, S.; Kumar, S.; Dey, S. K.

    2015-06-24

    Single crystal of a multicomponent salt (IMTBTP) of imidazole with tetrabromoterepthalic acid has been synthesized by slow evaporation method at room temperature. The crystal structure of the salt has been determined by single crystal x-ray diffraction technique. The supramolecular structure analysis reveals that the multicomponent salt is formed by noncovalent hydrogen bonding interaction and Br···π interaction. The energy optimization and HOMO-LUMO energy gap calculation have been carried out by Density Functional Theory.

  1. Onium salt structure/property relationships in poly(4-tert-butyloxycarbonyloxystyrene) deep-UV resists

    NASA Astrophysics Data System (ADS)

    Schwartzkopf, George; Niazy, Nagla N.; Das, Siddhartha; Surendran, Geetha; Covington, John B.

    1991-06-01

    A series of sulfonium and iodonium salts was synthesized and the effect of onium slat structure on UV absorbance, thermal stability, and solubility in propylene glycol methyl ether acetate (PGMEA) was assessed. Several of these onium salts gave usable deep UV photoresists when combined with poly(4-tert-butyloxy-carbonloxystyrene). The lithographic sensitivity and latent image stability of these photoresists were strongly influenced by the structure of the incorporated onium salt.

  2. [The morphological structure of salt gland and salt secretion in Aeluropus littoralis var. sinensis Debeaux].

    PubMed

    Liu, Zhi-Hua; Shi, Li-Ran; Zhao, Ke-Fu

    2006-08-01

    The leaves of Aeluropus littoralis var. sinensis Debeaux were scanned with a scanning electron microscope, it showed that the upper-epidermis had almost the same number of salt glands as the lower-epidermis (Plate I-1, 2), and the salt gland is the typical bicelluar gland, which consists of a large basal cell inlaid into the epidermis and a small cap cell (Plate I-6). These salt glands were distributed mainly on the leaf veins, which favors the rapid collection of salts from the roots. Ion X-ray microanalysis indicated that the salt glands could effectively absorb Na(+) from the epidermal cells and mesophyllous cells (Table 1), then secreted Na(+) from the cap cells (Plate I-4), which would decrease the salinity of plant. After the plants were treated with various salts for 17 d, the ion contents of the leaves and the secretion were measured, and the results implied that salt glands had different selection in absorbing and secreting Na(+) , K(+) and Ca(2+), that is, the plants first selected K(+) when absorbing ions, while first selected Na(+) when sending ions out, but Ca(2+) was fewer in both absorbed and secreted, and the order of secretion of the three ions was found to be Na(+)>K(+)>Ca(2+) (Figs. 1-6). The secretion of Na(+) or three ions were respectively higher than that of leaves within 24 h (Figs. 1, 2, 7, 8), while K(+) situation was completely opposite with them (Figs. 3, 4). At the same time, the total ion content and composition inside the leaves remained more or less constant (Fig. 8). PMID:16957392

  3. Crystal structure of bile salt hydrolase from Lactobacillus salivarius.

    PubMed

    Xu, Fuzhou; Guo, Fangfang; Hu, Xiao Jian; Lin, Jun

    2016-05-01

    Bile salt hydrolase (BSH) is a gut-bacterial enzyme that negatively influences host fat digestion and energy harvesting. The BSH enzyme activity functions as a gateway reaction in the small intestine by the deconjugation of glycine-conjugated or taurine-conjugated bile acids. Extensive gut-microbiota studies have suggested that BSH is a key mechanistic microbiome target for the development of novel non-antibiotic food additives to improve animal feed production and for the design of new measures to control obesity in humans. However, research on BSH is still in its infancy, particularly in terms of the structural basis of BSH function, which has hampered the development of BSH-based strategies for improving human and animal health. As an initial step towards the structure-function analysis of BSH, C-terminally His-tagged BSH from Lactobacillus salivarius NRRL B-30514 was crystallized in this study. The 1.90 Å resolution crystal structure of L. salivarius BSH was determined by molecular replacement using the structure of Clostridium perfringens BSH as a starting model. It revealed this BSH to be a member of the N-terminal nucleophile hydrolase superfamily. Crystals of apo BSH belonged to space group P21212, with unit-cell parameters a = 90.79, b = 87.35, c = 86.76 Å (PDB entry 5hke). Two BSH molecules packed perfectly as a dimer in one asymmetric unit. Comparative structural analysis of L. salivarius BSH also identified potential residues that contribute to catalysis and substrate specificity. PMID:27139829

  4. Combination of Geophysical Methods for Measuring the Structure of Rock Glaciers

    NASA Astrophysics Data System (ADS)

    Ikeda, A.

    2007-12-01

    The internal structure of talus-derived rock glaciers was surveyed by a combination of electrical resistivity and refraction seismic measurements to study effects of lithological and thermal situations on the development of rock glaciers. P-wave velocity, direct current (DC) resistivity and/or year-round ground surface temperature were measured on 32 rock glaciers in the Alps and 6 rock glaciers in the Brooks Range, Alaska. In the Alps, two lithological situations were compared: one resulted in bouldery rock glaciers covered with matrix-free boulders and the other pebbly rock glaciers consisting of matrix-supported pebbles and cobbles. Different structure accompanying permafrost thawing was studied through the comparison of vegetated rock glaciers with (non- vegetated) bouldery/pebbly rock glaciers, because such vegetated rock glaciers have been regarded as relict in the Alps. In the Brooks Range located in the continuous permafrost area, bouldery rock glaciers are mostly vegetated but probably contain permafrost. The structural difference of rock glaciers between the Alps and much colder and drier Brooks Range is also discussed. In the Alps, subsurface P-wave velocity differed significantly between the bouldery/pebbly rock glaciers (>2 km/s) and the vegetated rock glaciers (<1 km/s). In addition, the bouldery/pebbly rock glaciers had lower surface temperatures than the vegetated rock glaciers. These results indicate the presence of permafrost in the former and the absence in the latter. DC resistivity differed between the bouldery (10-5000 kohmm) and pebbly (0.5-20 kohmm) rock glaciers, whereas the subsurface resistivity had similar values between the pebbly and vegetated types. The bouldery rock glaciers in the Brooks Range lacked high resistivity core (>100 kohmm). Thus, the difference in the resistivity does not reflect the ground temperature (e.g. frozen or unfrozen) but the structural difference (e.g. bouldery or pebbly). In particular, high resistivity

  5. Radiation damage measurements on rock salt and other minerals for waste disposal applications. Quarterly report, January 1, 1980-March 31, 1980

    SciTech Connect

    Swyler, K J; Loman, J M; Teutonico, L J; Elgort, G E; Levy, P W

    1980-04-10

    Different aspects of radiation damage in both synthetic NaCl crystals and various natural rock salt samples as well as granite, basalt and other minerals which will be important for radioactive waste disposal applications are being investigated. The principal means of measuring radiation damage is the determination of F-center concentrations, and the concentration and size of sodium metal colloid particles. Formation of these and other defects during irradiation and the annealing of defects and characterization of other processes occurring after irradiation are being studied as a function of dose rate, total dose, sample temperature during irradiation, strain applied prior to and during irradiation, etc. Measurements are being made on synthetic NaCl and natural rock salt samples from different geological locations, including some potential repository sites. It will be necessary to determine if radiation damage in the minerals from different localities is similar. If non-negligible differences are observed a detailed study must be made for each locality under consideration. Almost all current studies are being made on rock salt but other minerals particularly granite and basalt are being phased into the program. It is now established that radiation damage formation in both natural and synthetic rock salt is strongly dependent on strain. The strain related effects strongly indicate that the damage formation processes and in particular the colloid nucleation processes are related to the strain induced disolcations. A temporary theoretical effort has been started to determine which dislocation related effects are important for radiation damage processes and, most importantly, what dislocation interactions are most likely to create nucleation sites for colloid particles. If these preliminary studies indicate that additional theoretical studies will be useful an effort will be made to have them extended.

  6. Salt restrains maturation in subsalt plays

    SciTech Connect

    Mello, U.T. ); Anderson, R.N.; Karner, G.D. . Lamont-Doherty Earth Observatory)

    1994-01-31

    The thermal positive anomaly associated with the top of salt diapirs has attracted significant attention in modifying the temperature structure and history of a sedimentary basin. Here the authors explore the role of the negative thermal anomaly beneath salt in modifying the maturation history of the source rocks in subsalt sediments. Organic matter maturation is believed to follow temperature dependent chemical reactions. Therefore, any temperature anomaly associated with salt masses affects the nearby maturation of potential source rocks. The level of maturity of source rocks close to salt diapirs will differ from that predicted based on regional trends. The impact of the thermal anomaly on a given point will depend on the duration and distance of the thermal anomaly to this particular point. Consequently, the maturation history of source rocks in salt basins is closely related to the salt motion history, implying that a transient thermal analysis is necessary to evaluate the sure impact on maturation of the thermal anomalies associated with salt diapirism. The paper describes vitrinite kinetics, salt in evolving basins, correlation of salt and temperature, salt dome heat drains, and restrained maturation.

  7. The large scale structures of the Late Permian Zechstein 3 intra-salt stringer, northern Netherlands

    NASA Astrophysics Data System (ADS)

    van Gent, H.; Strozyk, F.; Urai, J. L.; de Keijzer, M.; Kukla, P. A.

    2012-04-01

    The three dimensional study of the internal structure of salt structures on the several different scales is of fundamental importance to understand mechanisms of salt tectonics, for intra-salt storage cavern stability, and for drilling in salt-prone petroleum systems with associated problems like borehole instability and overpressured fluids. While most salt-related studies depict salt as structureless bodies, detailed field-, well- and mining gallery mapping have shown an amazing spectrum of brittle, complexly folded, faulted and boudinaged intra-salt layers ("stringers"), but mostly on a very local scale. First detailed insights into these three-dimensionally heterogeneous and very complex structures of the layered evaporites were provided by observations in modern high-resolution 3D seismic data, such as across the Late Permian Zechstein in the Southern Permian Basin (SPB). In the northern Dutch onshore part of the SPB, the Z2 and Z3 halite interface is characterized by the seismically visible reflections of the 30-150 m thick Z3 anhydrite-carbonate layer that clearly resolves the complex intra-salt structure. This stringer shows a high fragmentation into blocks of several tens of meters to kilometres diameter with complexly folded and faulted structures that correlate to the regionally varying deformation stages of the Zechstein, as it is implied by the shape of Top Salt. After an extensive seismic mapping over the entire northern Netherlands, structures observed include an extensive network of thicker zones, inferred to result from early karstification. Later, this template of relatively strong zones was deformed into large scale folds and boudins as the result of salt tectonics. Non-plane-strain salt flow produced complex fold and boudin geometries that overprint each other. There are some indications of a feedback between the early internal evolution of this salt giant and the position of later salt structures. The stringer has a higher density then the

  8. Salt efflorescence due to water-rock interaction on the surface of tuff cave in the Yoshimi-Hyakuana Historic Site, central Japan

    NASA Astrophysics Data System (ADS)

    Oguchi, Chiaki T.; Kodama, Shogo; Mohammad, Rajib; Tharanga Udagedara, Dashan

    2016-04-01

    Artificial cave walls in Yoshimi Hyakuana Historic Site have been suffering from salt weathering since 1945 when the caves were made. To consider the processes of weathering and subsequent crystallization of secondary minerals, water-rock experiment using tuff from this area was performed. Rocks, surface altered materials, groundwater and rainwater were collected, and chemical and mineralogical characteristics of those samples were investigated. The XRD and SEM-EDS analyses were carried out for the solid samples and ICP-OES analysis was performed for the solution generated from the experiment, groundwater and rainwater. Gypsum is detected in original tuff, and on grey and whiter coloured altered materials. General chemical changes were observed on this rock. However, it is found that purple and black altered materials were mainly made due to microbiological processes.

  9. Neogene structural characteristics of Louisiana shelf with emphasis on growth-fault interplay with salt tectonics

    SciTech Connect

    Xue, Fangjian, Xi, Jiebo )

    1996-01-01

    Growth faulting and salt tectonics are the most pronounced structural features in the offshore Louisiana. Regional examination of seismic data(4 mile x 4 mile grid) of OCS area Suggests that polyphase halokinesis happened along the whole shelf area during the Neogene sedimentation but with different type of salt movement and faulting in time and space. The sublinear and regularly basinward-dipping lower and middle Miocene faults predominate beneath the present inner shelf region with scarcity of shallow salt features. These fault trends detached on bottom Miocene decollement related ductile shale and salt welds. The shorter and more arcuate-shaped upper Miocene and Pliocene faults complicated by abundant near-surface salt bodies characterize the farther offshore beneath the outer-shelf region. Most of these fault root into or related to salt diapirs, but at the West Cameron and at the South Timberlier, families of growth-faults were developed on the upper Miocene allochthonous salt sheet detachment and played an important role in segmenting salt sheet in this salt raft regime. The more irregularly oriented Pleistocene faults with combination of shallow basinward-dipping and counter-basinward-dipping detachment on top of large and thick upper Pliocene allochthonous salt mass occurred in the present shelf edge and slope region. This study suggest at least three episodes of salt movement occurred at early Miocene, late Miocene-early Pliocene and early Pleistocene and the existence and possible position of large right-slip transfer faults.

  10. Submarine allochthonous salt sheets: Gravity-driven deformation of North African Cretaceous passive margin in Tunisia - Bled Dogra case study and nearby salt structures

    NASA Astrophysics Data System (ADS)

    Masrouhi, Amara; Bellier, Olivier; Ben Youssef, Mohamed; Koyi, Hemin

    2014-09-01

    We used structural, stratigraphic and sedimentologic data, together with a comparison of nearby structures and a Bouguer gravity map, to evaluate the evolution of the Bled Dogra salt structure (northern Tunisia) during the Cretaceous. Triassic salt sheets are recognized in the northwestern region of the Tunisian Atlas. These salt sheets are the result of Cretaceous thick and/or thin-skinned extension along the south Tethyan margin. The Bled Dogra salt structure is one of these submarine allochthonous salt sheets, which was emplaced during the Early Cretaceous. The geologic framework, during this period, produces conditions for a predominantly gravity-driven deformation: extension has produced space for the salt to rise; vigorous differential sedimentation created differential loading that resulted in the emplacement and extrusion of a large volume of Triassic salt and formation of large submarine salt sheets. Geologic field data suggest an interlayered Triassic salt sheet within Albian sequences. Salt was extruded at the sea floor during the Early-Middle Albian and was initially buried by Middle-Late Albian strata. The Coniacian corresponds to a second transgressive cover onto the salt sheet after the gliding of the first salt cover (Late Albian-Turonian). In addition, this northwest Tunisian area exposes evidences for salt flow and abundant slump features at the base of a northward facing submarine slope, which was probably dominant from the Early Cretaceous to Santonian. Two gravity deformation processes are recognized: gravity gliding and gravity spreading. Acting concurrently, these two processes appear indistinguishable in this geologic context. Like the present-day salt-involved passive margins - such as the northern Gulf of Mexico, the Atlantic margin of Morocco, the Brazilian Santos basin, the Angola margin, Cadiz in western Iberia, and the Red Sea - the North African Cretaceous passive margin in Tunisia provides evidences that deformation in a passive

  11. Synthesis of rock-salt type lithium borohydride and its peculiar Li+ ion conduction properties

    NASA Astrophysics Data System (ADS)

    Miyazaki, R.; Maekawa, H.; Takamura, H.

    2014-05-01

    The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH4, known for its super Li+ ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH4, more suitable to the high rate condition. We synthesized the H.P. form of LiBH4 under ambient pressure by doping LiBH4 with the KI lattice by sintering. The formation of a KI - LiBH4 solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li+ conductor despite its small Li+ content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the "Parasitic Conduction Mechanism." This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  12. Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes

    NASA Astrophysics Data System (ADS)

    Lang, Jörg; Hampel, Andrea; Brandes, Christian; Winsemann, Jutta

    2014-10-01

    During the past decades the effect of glacioisostatic adjustment has received much attention. However, the response of salt structures to ice-sheet loading and unloading is poorly understood. Our study aims to test conceptual models of the interaction between ice-sheet loading and salt structures by finite-element modelling. The results are discussed with regard to their implications for ice-marginal and subglacial processes. Our models consist of 2D plane-strain cross-sections, which represent simplified geological cross-sections from the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic diapir and layer of salt and (iii) an elastoplastic basement. On top of the model, a temporarily variable pressure simulates the advance and retreat of an ice sheet. The durations of the individual loading phases were defined to resemble the durations of the Pleistocene ice advances in northern central Europe. The geometry and rheology of the model layers and the magnitude, spatial distribution and timing of ice-sheet loading were systematically varied to detect the controlling factors. All simulations indicate that salt structures respond to ice-sheet loading. An ice advance towards the diapir causes salt flow from the source layer below the ice sheet towards the diapir, resulting in an uplift of up to +4 m. The diapir continues to rise as long as the load is applied to the source layer but not to the crest of the diapir. When the diapir is transgressed by the ice sheet the diapir is pushed down (up to -36 m) as long as load is applied to the crest of the diapir. During and after ice unloading large parts of the displacement are compensated by a reversal of the salt flow. Plastic deformation of the overburden is restricted to the area immediately above the salt diapir. The displacements after unloading range between -3.1 and +2.7 m. Larger displacements are observed in models with deep-rooted diapirs

  13. Basin architecture, salt tectonics, and Upper Jurassic structural styles, DeSoto Canyon Salt basin, northeastern Gulf of Mexico

    SciTech Connect

    MacRae, G.; Watkins, J.S. )

    1993-10-01

    Despite the Gulf of Mexico being a mature hydrocarbon province, the least understood aspects of the basin's geologic history are undoubtedly those concerning pre-Middle Jurassic tectonic events and their implication for the tectonic and sedimentary evolution of the region. Despite awareness of the importance of continental extension during rifting, there are few quantitative studies that show the influence of crustal extension on basin architecture, the distribution of salt, and Late Jurassic sedimentation in the DeSoto Canyon Salt basin, northeastern Gulf of Mexico. Application of simplified isostatic principles using a lithospheric buoyancy model allow quantification of total tectonic subsidence, crustal thickness, crustal extension, and crust type. An average crustal thickness of 25 km and crustal extension [beta] values between 1.4 and 1.8 suggest the sedimentary succession is underlain by moderately stretched and attenuated continental crust. The widespread distribution and geometry of dipping subsalt reflectors, particularly in the shelfal areas, provide evidence for a Late Triassic-Early Jurassic phase of rifting prior to deposition of Middle Jurassic salt. Although deposition occurred in a slowly subsiding, stable marginal setting, salt movement and associated growth faulting are the most significant tectonic elements affecting the stratigraphic and structural development of the overlying strata.

  14. The role of salt in the structural development of central Utah

    USGS Publications Warehouse

    Witkind, Irving J.

    1994-01-01

    Multiple episodes of diapirism, probably salt generated, have determined the structural pattern of central Utah. The causative salt and other evaporites are integral components of the Arapien Shale of Middle Jurassic age, one of the most unusual stratigraphic units in central Utah.

  15. Relationships Between Watershed Emergy Flow and Coastal New England Salt Marsh Structure, Function, and Condition

    EPA Science Inventory

    This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI. The field-collected data wer...

  16. Salt tectonics and structural styles in the deep-water province of the Cabo Frio Region, Rio de Janeiro, Brazil

    SciTech Connect

    Mohriak, W.U.; Macedo, J.M.; Castellani, R.T.

    1996-12-31

    The Cabo Frio region, offshore Rio de Janeiro, lies between two of the most prolific Brazilian oil provinces, the Campos and Santos basins. Major geologic features have been identified using a multidisciplinary approach integrating seismic, gravity, petrographic, and borehole data. The Cabo Frio frontier region is characterized by marked changes in stratigraphy and structural style and is unique among the Brazilian marginal basins. Major geologic features include the deflection of the coastline and pre-Aptian hings line from northeast to east; a large east-striking offshore graben related to salt tectonics; a northwest-trending lineament extending from oceanic crust to the continent; basement-involved landward-dipping (antithetic) normal faults in shallow water; a stable platform in the southern Campos Basin; a thick sequence of postbreakup intrusive and extrusive rocks; and, near the Santos Basin, a mobilized sequence of deep-water postrift strata affected by landward-dipping listric normal faults. These faults are unusual in salt-related passive margins in that they dip landward, apparently detach on the Aptian salt, and show large late Tertiary offsets. Locally, the older sequences do not show substantial growth in the downthrown blocks. South of the Rio de Janeiro coast, a phenomenal landward-dipping fault system detaches blocks of the Albian platform to the north and, to the south, coincides with the depositional limit of the Albian platform. Two end-member processes of salt tectonics in the Cabo Frio region result in either synthetic or antithetic basal shear along the fault weld under the overburden: (1) thin-skinned processes, in which the listric faults were caused by salt flow in response to gravity forces related to massive clastic progradation from the continent; and (2) thick-skinned processes, in which faulting was indirectly triggered by diastrophic causes or disequilibrium in the basement topography.

  17. Depositional patterns and structural styles-Hackberry Salt Dome, Cameron Parish, Louisiana

    SciTech Connect

    Spencer, J.A.; Sharpe, C.L.; Gillham, T.H.; Wright, D.N.

    1994-12-31

    The West and East Hackberry fields of north-central Cameron Parish, Louisiana, are associated with a large southeast-plunging salt ridge. Episodes of salt movement influenced the depositional patterns and reservoir trap styles of the Oligocene- and Miocene-age sedimentary section. The Oligocene lower Hackberry channels were influenced by the salt structure, resulting in the Manchester-Holmwood channel system flanking the east and south sides of the salt dome and the Choupique channel system flanking the west side of the salt dome. The depositional patterns and structural bed dips of the younger Oligocene Camerina A to marginulina section demonstrate a major period of salt movement and erosion. The resulting truncation of the Camerian A sandstones, sealed by overlying shales, provides the dominant trap style for the majority of the reservoirs. This same general period of salt movement influenced the orientation of the Oligocene Marginulina to Miogypsinoides expansion fault system to the east. The Sweet Lake salt dome, down through to this expansion system, probably represents a southeast extension of this ancestral salt ridge.

  18. Modelling of the reactive transport for rock salt-brine in geological repository systems based on improved thermodynamic database (Invited)

    NASA Astrophysics Data System (ADS)

    Müller, W.; Alkan, H.; Xie, M.; Moog, H.; Sonnenthal, E. L.

    2009-12-01

    for both Pitzer ion-interaction parameters and thermodynamic equilibrium constants. The reliability of the parameters is as important as the accuracy of the modelling tool. For this purpose the project THEREDA (www.thereda.de)was set up. The project aims at a comprehensive and internally consistent thermodynamic reference database for geochemical modelling of near and far-field processes occurring in repositories for radioactive wastes in various host rock formations. In the framework of the project all data necessary to perform thermodynamic equilibrium calculations for elevated temperature in the system of oceanic salts are under revision, and it is expected that related data will be available for download by 2010-03. In this paper the geochemical issues that can play an essential role for the transport of radioactive contaminants within and around waste repositories are discussed. Some generic calculations are given to illustrate the geochemical interactions and their probable effects on the transport properties around HLW emplacements and on CO2 generating and/or containing repository systems.

  19. Electronic structure calculations on lithium battery electrolyte salts.

    PubMed

    Johansson, Patrik

    2007-03-28

    New lithium salts for non-aqueous liquid, gel and polymeric electrolytes are crucial due to the limiting role of the electrolyte in modern lithium batteries. The solvation of any lithium salt to form an electrolyte solution ultimately depends on the strength of the cation-solvent vs. the cation-anion interaction. Here, the latter is probed via HF, B3LYP and G3 theory gas-phase calculations for the dissociation reaction: LiX <--> Li(+) + X(-). Furthermore, a continuum solvation method (C-PCM) has been applied to mimic solvent effects. Anion volumes were also calculated to facilitate a discussion on ion conductivities and cation transport numbers. Judging from the present results, synthesis efforts should target heterocyclic anions with a size of ca. 150 A(3) molecule(-1) to render new highly dissociative lithium salts that result in electrolytes with high cation transport numbers. PMID:17356757

  20. Preliminary projections of the effects of chloride-control structures on the Quaternary aquifer at Great Salt Plains, Oklahoma

    USGS Publications Warehouse

    Reed, J.E.

    1982-01-01

    About 1,200 tons of chloride per day are added to the salt load of the Salt Fork of the Arkansas River at Great Salt Plains Lake from natural sources. The source of this chloride is brine discharge from the rocks of Permian age in the vicinity of the lake. The U.S. Army Corps of Engineers has planned a chloride-control project. The Corps requested that the U.S. Geological Survey use a digital model to project the effects of the chloride-control plan on ground water. Ground-water flow and ground-water transport models were calibrated to represent the Quaternary aquifer that is the near-surface part of the flow system. The models were used to project the effects of planned chloride-control structures. Based on model results, ground-water levels are projected to rise as much as 19 feet. However, these water-level rises will occur only in areas near three reservoirs. Changes in ground-water level caused by the project will be small throughout most of the area. Chloride concentration of ground water is projected to increase by more than 90,000 milligrams per liter at one location. However, significant increases in chloride concentration during the 50-year period simulated are projected to be limited to areas where the ground water already contains excessive chloride concentrations.

  1. Rheological contrasts in salt and their effects on flow in salt

    NASA Astrophysics Data System (ADS)

    Urai, Janos L.; Kukla, Peter A.

    2014-05-01

    The majority of numerical and analogue models of salt tectonics assume homogeneous rheological models, and consequently produce simple internal structures. This is in contrast to observations in salt mines and 3D seismic, showing complex folding at a wide range of scales, in combination with boudinage and fracturing, which point to large rheological contrasts in salt bodies. The rheology of rock salt during slow deformation can be both Newtonian and Power law. Dislocation creep and dissolution-precipitation processes, such as solution-precipitation creep and dynamic recrystallisation, both play a significant role and grain boundary healing in deforming salt may result in cyclic softening and hardening behaviour. The switch between these processes can cause major changes in rock salt rheology, at time scales both relevant to geologic evolution and subsurface operations. In the dislocation creep field, a compilation of laboratory data show that different rock salts can creep at four orders of magnitude different strain rates under otherwise the same conditions. Potassium - Magnesium salts are in turn much weaker, and Anhydrite much stronger than rock salt. Anhydrite - carbonate inclusions embedded in deforming salt bodies respond to the movements of the salt in a variety of ways including boudinage and folding. New methods of microstructure analysis integrated with paleorheology indicators observed in natural laboratories allows an integration of these data and the development of a unified model for salt creep for both underground cavities and natural deformation, including the effect of high fluid pressures in salt which lead to a dramatic increases in permeability. For example, modeling of anhydrite stringer sinking is an important way to obtain the long term rheology of the halite, indicating that the rheology of Zechstein salt during the Tertiary was dominated by dislocation creep. These form the basis of a new generation of mechanical models to predict the

  2. Aspects of the thermal and transport properties of crystalline salt in designing radioactive waste storages in halogen formations

    SciTech Connect

    Nikitin, A. N. Pocheptsova, O. A.; Matthies, S.

    2010-05-15

    Some of the properties of natural rock salt are described. This rock is of great practical interest, because, along with its conventional applications in the chemical and food industries, it is promising for use in engineering underground radioactive waste storages and natural gas reservoirs. The results of structural and texture studies of rock salt by neutron diffraction are discussed. The nature of the salt permeability under temperature and stress gradients is theoretically estimated.

  3. The Rock Elm meteorite impact structure, Wisconsin: Geology and shock-metamorphic effects in quartz

    USGS Publications Warehouse

    French, B.M.; Cordua, W.S.; Plescia, J.B.

    2004-01-01

    The Rock Elm structure in southwest Wisconsin is an anomalous circular area of highly deformed rocks, ???6.5 km in diameter, located in a region of virtually horizontal undeformed sedimentary rocks. Shock-produced planar microstructures (PMs) have been identified in quartz grains in several lithologies associated with the structure: sandstones, quartzite pebbles, and breccia. Two distinct types of PMs are present: P1 features, which appear identical to planar fractures (PFs or cleavage), and P2 features, which are interpreted as possible incipient planar deformation features (PDFs). The latter are uniquely produced by the shock waves associated with meteorite impact events. Both types of PMs are oriented parallel to specific crystallographic planes in the quartz, most commonly to c(0001), ??112??2, and r/z101??1. The association of unusual, structurally deformed strata with distinct shock-produced microdeformation features in their quartz-bearing rocks establishes Rock Elm as a meteorite impact structure and supports the view that the presence of multiple parallel cleavages in quartz may be used independently as a criterion for meteorite impact. Preliminary paleontological studies indicate a minimum age of Middle Ordovician for the Rock Elm structure. A similar age estimate (450-400 Ma) is obtained independently by combining the results of studies of the general morphology of complex impact structures with estimated rates of sedimentation for the region. Such methods may be applicable to dating other old and deeply eroded impact structures formed in sedimentary target rocks.

  4. Depositional patterns and structural styles - Hackberry Salt Dome, Cameron Parish, Louisiana

    SciTech Connect

    Spencer, J.A.; Sharpe, C.L.; Gillham, T.H.

    1994-09-01

    The west and east Hackberry fields of north-central Cameron Parish, Louisiana, are associated with a large southeast-plunging salt ridge. Episodes of salt movement influenced the depositional patterns and reservoir trap styles of the Oligocene and Miocene age section. The Oligocene lower Hackberry channels were influenced by the salt, resulting in the {open_quotes}Manchester-Holmwood{close_quotes} channel system skirting the east and south flanks of the salt and the {open_quotes}Choupique{close_quotes} channel system skirting the west flank of the salt. The depositional patterns and structural bed dips of the younger Oligocene Camerina (A) to Marginulina section demonstrate a major period of salt movement and erosion. The resulting truncation of the Camerina (A) sands, sealed by overlying shales, provides the dominant trap style for the majority of the fields` reservoirs. This same general period of salt movement influenced the orientation of the Oligocene Camerina (A) - Miogypsinoides expansion fault systems of the prolific Miogypsinoides embayment. The Sweet Lake salt dome, downthrown to this expansion system, probably represents a southeast extension of this ancestral salt ridge.

  5. Rheological stratification in Zechstein rock salt caused by thermodynamically controlled reorganization of grain boundary fluids? A test using gravitationally induced sinking of anhydrite-dolomite stringers.

    NASA Astrophysics Data System (ADS)

    Urai, Janos L.; Raith, Alexander F.

    2016-04-01

    The rheology of rock salt during slow deformation in nature is controlled by the dominant deformation mechanism. Newtonian viscous rheology is associated with solution precipitation processes, while power law rheology is associated with dislocation creep. In large strain deformation during salt tectonics these two processes both contribute equally to the total strain rate, and grain boundaries contain mobile brine films. It has been shown that after the end of active salt tectonics, these fluid films neck down into arrays of disconnected brine inclusions, rendering the grain boundaries immobile and thus stopping solution-precipitation creep. This results in very low gravitational sinking rates of isolated anhydrite-dolomite stringers in Zechstein salt in the Tertiary, consistent with power law creep, while in Newtonian salt the stringers would sink to the bottom in geologically short time. In a recent paper Ghanbarzadeh et al., (Science, Nov 2015) provided evidence that below approximately 2 km depth the thermodynamically controlled dihedral angle between solid-liquid and solid-solid grain boundaries decreases to below 60 degrees, so that a connected grain boundary triple junction network of fluid channels is formed and permeability of the salt increases. The same process can be argued to lead to permanently mobile grain boundaries below this critical depth, activating solution-precipitation creep even in the absence of active tectonics. We test this hypothesis by comparing estimated gravitationally induced sinking rates of isolated anhydrite-dolomite stringers in the Zechstein of NE-Netherlands, based on 3D sesmic data, at depths above and below this proposed transition. First results suggest that there is no significant change in stringer sinking rate with depth.

  6. Design, Synthesis, and Structure-Activity Relationships of Pyridine-Based Rho Kinase (ROCK) Inhibitors.

    PubMed

    Green, Jeremy; Cao, Jingrong; Bandarage, Upul K; Gao, Huai; Court, John; Marhefka, Craig; Jacobs, Marc; Taslimi, Paul; Newsome, David; Nakayama, Tomoko; Shah, Sundeep; Rodems, Steve

    2015-06-25

    The Rho kinases (ROCK1 and ROCK2) are highly homologous serine/threonine kinases that act on substrates associated with cellular motility, morphology, and contraction and are of therapeutic interest in diseases associated with cellular migration and contraction, such as hypertension, glaucoma, and erectile dysfunction. Beginning with compound 4, an inhibitor of ROCK1 identified through high-throughput screening, systematic exploration of SAR, and application of structure-based design, led to potent and selective ROCK inhibitors. Compound 37 represents significant improvements in inhibition potency, kinase selectivity, and CYP inhibition and possesses pharmacokinetics suitable for in vivo experimentation. PMID:26039570

  7. Carbonate Melt Rocks from the Haughton Impact Structure, Devon Island, Nunavut, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Spray, J. G.; Lee, P.

    2002-01-01

    The target rocks at the Haughton impact structure, Canada, are predominantly carbonates. The well preserved allochthonous crater-fill deposits are reinterpreted here as being carbonatitic impact melt rocks. The implications of our findings will be discussed. Additional information is contained in the original extended abstract.

  8. Synergistic effect of temperature, protein and salt concentration on structures and interactions among lysozyme proteins

    NASA Astrophysics Data System (ADS)

    Kundu, Sarathi; Aswal, V. K.; Kohlbrecher, Joachim

    2016-07-01

    Synergistic effect of temperature, protein and salt concentration on structures and interactions among lysozyme proteins in solution has been studied using small angle neutron scattering technique. Scattering study shows that for a particular protein concentration, with increasing temperature, short-range attraction decreases but long-range repulsion becomes system specific. In absence of salt, lower value of attractive interaction is obtained, however, in presence of salt it becomes higher and decreases with increasing temperature. For specific condition, weak long range attraction and intermediate range repulsion exists. At higher temperature (90 °C), fractal structure develops and the corresponding fractal dimension depends upon the experimental conditions.

  9. Conformation of the umifenovir cation in the molecular and crystal structures of four carboxylic acid salts

    NASA Astrophysics Data System (ADS)

    Orola, Liana; Sarcevica, Inese; Kons, Artis; Actins, Andris; Veidis, Mikelis V.

    2014-01-01

    The umifenovir salts of maleic, salicylic, glutaric, and gentisic acid as well as the chloroform solvate of the salicylate were prepared. Single crystals of the five compounds were obtained and their molecular and crystal structures determined by X-ray diffraction. In each structure the conformation of phenyl ring with respect to the indole group of the umifenovir moiety is different. The water solubility and melting points of the studied umifenovir salts have been determined.

  10. Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt

    PubMed Central

    Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir

    2014-01-01

    Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution powder X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid⋯pyridine heterosynthon and N—H⋯O catemer hydrogen bonds involving the amide group. The acid⋯amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl⋯carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM–PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine

  11. Salt deposits in Los Medanos area, Eddy and Lea counties, New Mexico

    USGS Publications Warehouse

    Jones, C.L.; with sections on Ground water hydrology, Cooley, Maurice E.; and Surficial Geology, Bachman, George Odell

    1973-01-01

    The salt deposits of Los Medanos area, in Eddy and Lea Counties, southeastern New Mexico, are being considered for possible use as a receptacle for radioactive wastes in a pilot-plant repository. The salt deposits of the area. are in three evaporite formations: the Castile, Salado, and Rustler Formations, in ascending order. The three formations are dominantly anhydrite and rock salt, but some gypsum, potassium ores, carbonate rock, and fine-grained clastic rocks are present. They have combined thicknesses of slightly more than 4,000 feet, of which roughly one-half belongs to the Salado. Both the Castile and the Rustler are-richer in anhydrite-and poorer in rock salt-than the Salado, and they provide this salt-rich formation with considerable Protection from any fluids which might be present in underlying or overlying rocks. The Salado Formation contains many thick seams of rock salt at moderate depths below the surface. The rock salt has a substantial cover of well-consolidated rocks, and it is very little deformed structurally. Certain geological details essential for Waste-storage purposes are unknown or poorly known, and additional study involving drilling is required to identify seams of rock salt suitable for storage purposes and to establish critical details of their chemistry, stratigraphy, and structure.

  12. Structure and vibrational spectra of the salts of mononitroalkanes

    NASA Astrophysics Data System (ADS)

    Shlyapochnikov, V. A.; Tafipolsky, M. A.; Tokmakov, I. V.; Oleneva, G. I.

    2000-03-01

    The molecular geometries of the anions of nitromethane and 2-nitropropane were optimised and their harmonic force fields were calculated by the RHF/6-311G(d,p), MP2/6-311G(d,p) and B3LYP/6-311G(d,p) methods. The force fields obtained made it possible to reliably interpret the IR and Raman spectra of the Na + salt of nitromethane, d2-nitromethane and 2-nitropropane. The assignment proposed significantly improves the interpretation of vibrational spectra known so far. Some general conclusions on geometry and vibrational spectra of the salts of mononitroalkanes studied are made. The hybrid density functional method used (B3LYP) is shown to be in better agreement with experimental data available than the Hartree-Fock methods.

  13. The adsorption-desorption behaviour and structure function relationships of bile salts.

    PubMed

    Parker, Roger; Rigby, Neil M; Ridout, Michael J; Gunning, A Patrick; Wilde, Peter J

    2014-09-14

    The digestion of dietary components in the human gastrointestinal (GI) tract is a complex, dynamic, inherently heterogeneous process. A key aspect of the digestion of lipid in the GI tract is the combined action of bile salts, lipase and colipase in hydrolysing and solubilising dispersed lipid. The bile salts are a mixture of steroid acid conjugates with surfactant properties. In order to examine whether the different bile salts have different interfacial properties their dynamic interfacial behaviour was characterised. Differences in the adsorption behaviour to solid hydrophobic surfaces of bile salt species were studied using dual polarisation interferometry and atomic force microscopy (AFM) under physiological conditions. Specifically, the cholates adsorbed more slowly and a significant proportion were irreversibly adsorbed following buffer rinsing; whereas the deoxycholates and chenodeoxycholates adsorbed more rapidly and desorbed to a greater extent following buffer rinsing. The conjugating groups (taurine, glycine) did not influence the behaviour. AFM showed that the interfacial structures that remained following buffer rinsing were also different between these two groups. In addition, the adsorption-desorption behaviour affected the adsorption of colipase to a solid surface. This supports the idea that cooperative adsorption occurs between certain bile salts and colipase to facilitate the adsorption and activity of pancreatic lipase in order to restore lipolytic activity in the presence of bile salts. This study provides insights into how differences in bile salt structure could affect lipase activity and solubilisation of lipolysis products and other lipid-soluble bioactive molecules. PMID:25008989

  14. Physical modeling of river spanning rock structures: Evaluating interstitial flow, local hydraulics, downstream scour development, and structure stability

    USGS Publications Warehouse

    Collins, K.L.; Thornton, C.I.; Mefford, B.; Holmquist-Johnson, C. L.

    2009-01-01

    Rock weir and ramp structures uniquely serve a necessary role in river management: to meet water deliveries in an ecologically sound manner. Uses include functioning as low head diversion dams, permitting fish passage, creating habitat diversity, and stabilizing stream banks and profiles. Existing information on design and performance of in-stream rock structures does not provide the guidance necessary to implement repeatable and sustainable construction and retrofit techniques. As widespread use of rock structures increases, the need for reliable design methods with a broad range of applicability at individual sites grows as well. Rigorous laboratory testing programs were implemented at the U.S. Bureau of Reclamation (Reclamation) and at Colorado State University (CSU) as part of a multifaceted research project focused on expanding the current knowledge base and developing design methods to improve the success rate of river spanning rock structures in meeting project goals. Physical modeling at Reclamation is being used to measure, predict, and reduce interstitial flow through rock ramps. CSU is using physical testing to quantify and predict scour development downstream of rock weirs and its impact on the stability of rock structures. ?? 2009 ASCE.

  15. Mössbauer study of two different aged rock types in the Vredefort structure, South Africa

    NASA Astrophysics Data System (ADS)

    Waanders, F. B.; Brink, M. C.; Bisschoff, A. A.

    2005-11-01

    The Vredefort Structure in South Africa was recently inscribed into the list of World Heritage sites as the oldest and largest recognised impact structure on earth. Due to upliftment of more than 30 km of the Archaean basement core and subsequent exposure of the deeply eroded central portion of the crater a unique opportunity exists to study rocks of the crust, especially those that have undergone recrystallization due to various thermal metamorphic events over time. Two rock types occurring in the central uplifted part of the impact structure were studied. One was a typical Archaean iron formation of sedimentary origin. The other rock studied, adjacent to this much older rock, is a homogeneous, medium grained recrystallized norite of immediately pre- or post-impact age, indicating a possible mafic igneous activity related to impact. Microscopy, XRD and Mössbauer analyses were performed on both samples.

  16. Surface diffusivity of cleaved NaCl crystals as a function of humidity: Impedance spectroscopy measurements and implications for crack healing in rock salt

    NASA Astrophysics Data System (ADS)

    Koelemeijer, Paula J.; Peach, Colin J.; Spiers, Christopher J.

    2012-01-01

    Rock salt offers an attractive host rock for geological storage applications, because of its naturally low permeability and the ability of excavation-induced cracks to heal by fluid-assisted diffusive mass transfer. However, while diffusive transport rates in bulk NaCl solution are rapid and well characterized, such data are not directly applicable to storage conditions where crack walls are coated with thin adsorbed water films. To reliably predict healing times in geological storage applications, data on mass transport rates in adsorbed films are needed. We determined the surface diffusivity in such films for conditions with absolute humidities (AH) ranging from 1 to 18 g/m3 (relative humidities (RH) of 4%-78%) by measuring the surface impedance of single NaCl crystals. We use the impedance results to calculate the effective surface diffusivity S = DδCusing the Nernst-Einstein equation. TheS values obtained lie in the range 1 × 10-27 m3 s-1 at very dry conditions to 1 × 10-19 m3 s-1 for the deliquescence point at 296 K, which is in reasonable agreement with existing values for grain boundary diffusion under wet conditions. Estimates for the diffusivity D made assuming a film thickness δ of 50-90 nm and no major effects of thickness on the solubility C lie in the range of 1 × 10-14 to 8 × 10-12 m2 s-1 for the highest humidities studied (14-18 g/m3 AH, 60%-78% RH). For geological storage systems in rock salt, we predict S values between 1 × 10-22 - 8 × 10-18 m3 s-1. These imply crack healing rates 6 to 7 orders of magnitude lower than expected for brine-filled cracks.

  17. Solid solutions between LaN and Ca{sub 3}N{sub 2}: Defect rock salt nitrides La{sub 1-x}Ca{sub x}N{sub 1-x/3}

    SciTech Connect

    Clarke, S.J.; DiSalvo, F.J.

    1997-02-15

    La{sub 1-x}Ca{sub x}N{sub 1-x/3} (0 < x < 0.7) has been prepared by reacting LaN with Ca{sub 3}N{sub 2} at temperatures between 1200 and 1300{degrees}C. All the phases have the LaN-like rock-salt structure with no evidence for ordering between La and Ca or of the x/3 N vacancies. The lattice parameters of materials with different compositions lie between those of the isostructural LaN and CaNH according to Vegard law. Ca adopts octahedral coordination in the title compound, in contrast to its tetrahedral coordination geometry in Ca{sub 3}N{sub 2}. The materials are poorly conducting.

  18. Using crystal structure prediction to rationalize the hydration propensities of substituted adamantane hydrochloride salts.

    PubMed

    Mohamed, Sharmarke; Karothu, Durga Prasad; Naumov, Panče

    2016-08-01

    The crystal energy landscapes of the salts of two rigid pharmaceutically active molecules reveal that the experimental structure of amantadine hydrochloride is the most stable structure with the majority of low-energy structures adopting a chain hydrogen-bond motif and packings that do not have solvent accessible voids. By contrast, memantine hydrochloride which differs in the substitution of two methyl groups on the adamantane ring has a crystal energy landscape where all structures within 10 kJ mol(-1) of the global minimum have solvent-accessible voids ranging from 3 to 14% of the unit-cell volume including the lattice energy minimum that was calculated after removing water from the hydrated memantine hydrochloride salt structure. The success in using crystal structure prediction (CSP) to rationalize the different hydration propensities of these substituted adamantane hydrochloride salts allowed us to extend the model to predict under blind test conditions the experimental crystal structures of the previously uncharacterized 1-(methylamino)adamantane base and its corresponding hydrochloride salt. Although the crystal structure of 1-(methylamino)adamantane was correctly predicted as the second ranked structure on the static lattice energy landscape, the crystallization of a Z' = 3 structure of 1-(methylamino)adamantane hydrochloride reveals the limits of applying CSP when the contents of the crystallographic asymmetric unit are unknown. PMID:27484376

  19. Influence of pre-existing salt structures in the 3D pattern of multilayer folding

    NASA Astrophysics Data System (ADS)

    Fernandez, Naiara; Kaus, Boris J. P.; Collignon, Marine

    2014-05-01

    Upward movement of the Precambrian Hormuz salt in the Fars region of the Zagros is supposed to have started as early as Late Cretaceous. The Late Cretaceous - Tertiary deformation events that lead to the folding of the sedimentary cover in this area would have therefore, enhance the upward salt movement by squeezing the pre-existing salt structures. How these salt diapirs evolve under such compressive events has already been previously addressed using analogue models (e.g. Callot et al. 2012). The same authors observed that pre-existing salt structures control the size and geometry of folds in sandbox models. Our previous work has shown that 3D folding instability gives rise to a wide variety of fold shapes (e.g. from dome shape structures to long en echelon or straight anticlines), resulting of the interactions between growing fold segments. The three dimensional growth of these folds, the wavelength and the lateral propagation, is itself controlled by physical parameters. However, the existence of initial weak zones such as pre-existing salt plugs within the sedimentary cover can affect the development of such folds by localizing part of the deformation. In this study we have used numerical modeling to investigate how the fold pattern in 3D multilayer folding is affected by pre-existing salt structures. High-resolution 3D folding simulations (with and without pre-existing salt structures) were performed with the parallel code LaMEM. Cylindrically shaped diapirs with different diameters and heights have been added to a multilayer folding setup. The use of a finite element based landscape evolution model (both erosion and sedimentation) allows for initially buried salt diapirs to be exposed at the surface during folding evolution. Acknowledgements Funding was provided by the European Research Council under the European Community's Seventh Framework program (FP7/2007-2013) ERC Grant agreement #258830. 3D simulations are performed in the IBM Blue Gene/Q JUQUEEN

  20. Reverse modeling of 2D and 3D diapiric salt structures

    NASA Astrophysics Data System (ADS)

    Fernandez, N.; Kaus, B.

    2013-12-01

    Mechanical forward modeling of salt diapirs formed by two different processes (differential loading and buoyancy driven) has been widely performed with numerical codes in many studies, whereas works focusing on the dynamic retro-deformation of such structures remain scarce. Buoyancy driven diapirs, in which the density difference between salt and overburden induces upward motion of salt, have been successfully retro-deformed in two and three dimensions using simple rheologies for the salt and overburden (e.g., Kaus & Podladchikov 2001). However, retro-deformation of down-building diapirs (syndepositional process in which salt structures grow while sediments are being deposited) using mechanical codes has only been done in two dimensions (e.g., Ismael-Zadeh et al. 2001), even though the importance of three-dimensionality in salt diapirism is accepted. We have used the two-dimensional visco-elasto-plastic finite element code MILAMIN_VEP to perform both forward and backward simulations and to check the validity of a reversed time step method (Kaus & Podladchikov 2001 and Ismael-Zadeh et al. 2001) for a wide range of parameters, variable sedimentation rates, and for non-linear rheologies. Forward simulations are run until the salt layer is exhausted and then a reverse time step is applied in order to retro-deform the model. Down-building process was mimicked using a fast-erosion condition at the surface, which keeps it flat and redistributes material at every time step. Initially, we have tested our method by retro-deforming salt structures that develop from an interface that is sinusoidally perturbed. More realistic simulations were performed by starting with randomly perturbed salt interface and using different rheological parameters for the salt and the overburden as well as variable sedimentation rates. Once the method has been proved successful for different parameters in two dimensions, the finite differences parallel code LaMEM has also been used to dynamically

  1. Geographic Variation in Plant Community Structure of Salt Marshes: Species, Functional and Phylogenetic Perspectives

    PubMed Central

    Guo, Hongyu; Chamberlain, Scott A.; Elhaik, Eran; Jalli, Inder; Lynes, Alana-Rose; Marczak, Laurie; Sabath, Niv; Vargas, Amy; Więski, Kazimierz; Zelig, Emily M.; Pennings, Steven C.

    2015-01-01

    In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in

  2. A salt-bridge structure in solution revealed by 2D-IR spectroscopy.

    PubMed

    Huerta-Viga, Adriana; Domingos, Sérgio R; Amirjalayer, Saeed; Woutersen, Sander

    2014-08-14

    Salt bridges are important interactions for the stability of protein conformations, but up to now it has been difficult to determine salt-bridge geometries in solution. Here we characterize the spatial structure of a salt bridge between guanidinium (Gdm(+)) and acetate (Ac(-)) using two-dimensional vibrational (2D-IR) spectroscopy. We find that as a result of salt bridge formation there is a significant change in the infrared response of Gdm(+) and Ac(-), and cross peaks between them appear in the 2D-IR spectrum. From the 2D-IR spectrum we determine the relative orientation of the transition-dipole moments of the vibrational modes of Gdm(+) and Ac(-), as well as the coupling between them. PMID:24676430

  3. Salts of phenylacetic acid and 4-hydroxyphenylacetic acid with Cinchona alkaloids: Crystal structures, thermal analysis and FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Amombo Noa, Francoise M.; Jacobs, Ayesha

    2016-06-01

    Seven salts were formed with phenylacetic acid (PAA), 4-hydroxyphenylacetic acid (HPAA) and the Cinchona alkaloids; cinchonidine (CIND), quinidine (QUID) and quinine (QUIN). For all the structures the proton was transferred from the carboxylic acid of the PAA/HPAA to the quinuclidine nitrogen of the respective Cinchona alkaloid. For six of the salts, water was included in the crystal structures with one of these also incorporating an isopropanol solvent molecule. However HPAA co-crystallised with quinine to form an anhydrous salt, (HPAA-)(QUIN+). The thermal stability of the salts were determined and differential scanning calorimetry revealed that the (HPAA-)(QUIN+) salt had the highest thermal stability compared to the other salt hydrates. The salts were also characterized using Fourier transform infrared spectroscopy. (PAA-)(QUID+)·H2O and (PAA-)(QUIN+)·H2O are isostructural and Hirshfeld surface analysis was completed to compare the intermolecular interactions in these two structures.

  4. Silicate-carbonate-salt liquid immiscibility and origin of the sodalite-haüyne rocks: study of melt inclusions in olivine foidite from Vulture volcano, S. Italy

    NASA Astrophysics Data System (ADS)

    Panina, Liya; Stoppa, Francesco

    2009-12-01

    Melt inclusions in clinopyroxenes of olivine foidite bombs from Serra di Constantinopoli pyroclastic flows of the Vulture volcano (Southern Italy) were studied in detail. The rocks contain abundant zoned phenocrysts and xenocrysts of clinopyroxene, scarce grains of olivine, leucite, haüyne, glass with microlites of plagioclase and K-feldspar. The composition of clinopyroxene in xenocrysts (Cpx I), cores (Cpx II), and in rims (Cpx III) of phenocrysts differs in the content of Mg, Fe, Ti, and Al. All clinopyroxenes contain two types of primary inclusion-pure silicate and of silicate-carbonate-salt composition. This fact suggests that the phenomena of silicate-carbonate immiscibility took place prior to crystallization of clinopyroxene. Homogenization of pure silicate inclusions proceeded at 1 225 - 1 190°C. The composition of conserved melts corresponded to that of olivine foidite in Cpx I, to tephrite-phonolite in Cpx II, and phonolite-nepheline trachyte in Cpx III. The amount of water in them was no more than 0.9 wt.%. Silicate-carbonate inclusions decrepitated on heating. Salt globules contained salts of alkali-sulphate, alkali-carbonate, and Ca-carbonate composition somewhat enriched in Ba and Sr. This composition is typical of carbonatite melts when decomposed into immiscible fractions. The formation of sodalite-haüyne rocks from Vulture is related to the presence of carbonate-salt melts in magma chamber. The melts conserved in clinopyroxenes were enriched in incompatible elements, especially in Cpx III. High ratios of La, Nb, and Ta in melts on crystallization of Cpx I and Cpx II suggest the influence of a carbonatite melt as carbonatites have extremely high La/Nb and Nb/Ta and this is confirmed by the appearance of carbonatite melts in magma chamber. Some anomalies in the concentrations and relatives values of Eu and especially Ga seems typical of Italian carbonatite related melts. The mantle source for initial melts was, most likely, rather uniform

  5. Rock fall susceptibility assessment using structural geological indicators for detaching processes such as sliding or toppling

    NASA Astrophysics Data System (ADS)

    Melzner, Sandra; Tilch, Nils; Lotter, Michael; Kociu, Arben

    2010-05-01

    A structural geological assessment of cliffs in terms of rock fall susceptibility is expensive and time-consuming particularly in remote areas (exposed cliffs) where it may even be impossible. Hence it is important to develop methods and strategies that can be used to extrapolate the acquired knowledge from representative sub-regions to the whole study area. Using a case study in Carinthia (Austria), a GIS method was developed which can be used for regional, qualitative determination of the susceptibility of cliffs in carbonatic sedimentary rock, regarding two potential initial detachment processes of rock fall: sliding and/or toppling. During the development of this GIS method, it was found that not all of the mapped structural geologic parameters are equally suitable for a comprehensive regionalisation. Subsequently, only those parameters were included in the assessment which experts deemed to be representative in terms of parameter homogeneity/heterogeneity and thus applicable to the entire survey region: bedding thickness, tectonic lineaments, orientation of discontinuities and type of rock mass structure. Regions of homogeneity/heterogeneity differ with regard to parameter values, as well as parameter uncertainties and scattering. At first, the cliffs were categorised in terms of potential form and size of rock blocks by overlaying various parameter maps. In the next step, the relative orientation of the rock mass structures and their variations towards slope aspect and slope inclination were considered within a region of homogeneity. This allowed an accurate estimate of the possible maximum dip angle (or apparent dip angle) of a joint set over a wide area. It also permitted those areas to be pointed out in which process-initialising sliding and/or toppling might be possible along one or several joint sets. Comparing this method to the acquired field data has proven the approach to be successful when it comes to assessing cliffs in carbonate rocks in terms of

  6. Ion pairing and salt structure in organic salts through diffusion, Overhauser, DFT and X-ray methods.

    PubMed

    Moreno, Aitor; Pregosin, Paul S; Veiros, Luis F; Albinati, Alberto; Rizzato, Silvia

    2009-07-13

    Pulsed gradient spin-echo (PGSE) diffusion characteristics for a) the new [brucinium][X] salts 6 a-f [a: X = BF(4)(-); b: X = PF(6)(-); c: X = MeSO(3)(-), d: X = CF(3)SO(3)(-); e: X = BArF(-); f: X = PtCl(3)(C(2)H(4))(-)], b) 4-tert-butyl-N-benzyl analogue, 7 and c) the aryl carbocations (p-R-C(6)H(4))(2)CH 9 a (R = CH(3)O) and 9 b (R = (CH(3))(2)N), (p-CH(3)O-C(6)H(4))(x)CPh(3-x)(+) 10 a-c (x = 1-3, respectively) and (p-R-C(6)H(4))(3)C(+) 11 (R = (CH(3))(2)N) and 12 (R = H) all in several different solvents, are reported. The solvent dependence suggests strong ion pairing in CDCl(3), intermediate ion pairing in CD(2)Cl(2) and little ion pairing in [D(6)]acetone. (1)H, (19)F HOESY NMR spectra (HOESY: heteronuclear Overhauser effect spectroscopy) for 6 and 7 reveal a specific approach of the anion with respect to the brucinium cation plus subtle changes, which are related to the anion itself. Further, for carbocations 9-12, (all as BF(4)(-) salts) based on the NOE results, one finds marked changes in the relative positions of the BF(4)(-) anion. In these aryl cationic species the anion can be located either a) very close to the carbonium ion carbon b) in an intermediate position or c) proximate to the N or O atom of the p-substituent and remote from the formally positive C atom. This represents the first example of such a positional dependence of an anion on the structure of the carbocation. DFT calculations support the experimental HOESY results. The solid-state structures for 6 c and the novel Zeise's salt derivative, [brucinium][PtCl(3)(C(2)H(4))], 6 f, are reported. Analysis of (195)Pt NMR and other NMR measurements suggest that the eta(2)-C(2)H(4) bonding to the platinum centre in 6 f is very similar to that found in K[PtCl(3)(C(2)H(4))]. Field dependent T(1) measurements on [brucinium][PtCl(3)(C(2)H(4))] and K[PtCl(3)(C(2)H(4))], are reported and suggested to be useful in recognizing aggregation effects. PMID:19504520

  7. The Surface Structure of Concentrated Aqueous salt Solutions

    SciTech Connect

    Sloutskin,E.; Baumert, J.; Ocko, B.; Kuzmenko, I.; Checco, A.; Tamam, L.; Ofer, E.; Gog, T.; Deutsch, M.

    2007-01-01

    The surface-normal electron density profile {rho}{sub s}(z) of concentrated aqueous salt solutions of RbBr, CsCl, LiBr, RbCl, and SrCl{sub 2} was determined by x-ray reflectivity (XR). For all but RbBr and SrCl{sub 2} {rho}{sub s}(z) increases monotonically with depth z from {rho}{sub s}(z)=0 in the vapor (z<0) to {rho}{sub s}(z) = {rho}{sub b} of the bulk (z>0) over a width of a few angstroms. The width is commensurate with the expected interface broadening by thermally excited capillary waves. Anomalous (resonant) XR of RbBr reveals a depletion at the surface of Br{sup -} ions to a depth of {approx}10 A. For SrCl{sub 2}, the observed {rho}{sub s}(z)>{rho}{sub b} may imply a similar surface depletion of Cl{sup -} ions to a depth of a few angstroms. However, as the deviations of the XRs of RbBr and SrCl{sub 2} from those of the other solutions are small, the evidence for a different ion composition in the surface and the bulk is not strongly conclusive. Overall, these results contrast earlier theoretical and simulational results and nonstructural measurements, where significant surface layering of alternate, oppositely charged, ions is concluded.

  8. Structure, stability, and tsunami hazard associated with a rock slope in Knight Inlet, British Columbia

    NASA Astrophysics Data System (ADS)

    van Zeyl, D. P.; Stead, D.; Sturzenegger, M.; Bornhold, B. D.; Clague, J. J.

    2015-06-01

    Rockfalls and rockslides during the past 12 000 years have deposited bouldery debris cones on the seafloor beneath massive rock slopes throughout the inner part of Knight Inlet. The 885 m high rock slope, located across from a former First Nations village destroyed in the late 1500s by a slide-induced wave, exposes the contact between a Late Cretaceous dioritic pluton and metamorphic rocks of the Upper Triassic Karmutsen Formation. The pluton margin is strongly foliated parallel to primary and secondary fabrics in the metamorphic rocks, resulting in highly persistent brittle structures. Other important structures include a set of sheeting joints and highly persistent mafic dykes and faults. Stability analysis indicates that planar and wedge rock slope failures up to about 500 000 m3 in volume could occur. We suspect that failures of this size in this setting would have the potential to generate locally hazardous waves. As several similar rock slopes fronted by large submarine debris cones exist in the inner part of Knight Inlet, it is clear that tsunami hazards should be considered in coastal infrastructure development and land-use planning in this area.

  9. Structure instability forecasting and analysis of giant rock pillars in steeply dipping thick coal seams

    NASA Astrophysics Data System (ADS)

    Lai, Xing-ping; Sun, Huan; Shan, Peng-fei; Cai, Ming; Cao, Jian-tao; Cui, Feng

    2015-12-01

    Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams (SDTCS) are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining- induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sandwiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam (TSFB). Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB's height (Δ H), which varied from 56.37 to 60.50 m. Next, FLAC3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission (AE) energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS.

  10. Tidal events and salt-marsh structure influence black mangrove (Avicennia germinans) recruitment across an ecotone.

    PubMed

    Peterson, Jennifer M; Bell, Susan S

    2012-07-01

    Field experiments were conducted at a black mangrove-salt-marsh ecotone in southwest Florida (U.S.A.) to investigate retention of propagules of the black mangrove, Avicennia germinans, by salt-marsh plants as a mechanism of facilitation operating on recruitment success at landward boundaries. Buoyant A. germinans propagules are dispersed by tides, and stranding is required for establishment; therefore, processes that enable stranding should facilitate mangrove recruitment. We expected the physical structure of salt-marsh vegetation to define propagule retention capacity, and we predicted that salt-marsh plants with distinct growth forms would differentially retain propagules. Experimental monoculture plots (1 m2) of salt-marsh plants with different growth forms (Sporobolus virginicus [grass], Sesuvium portulacastrum [succulent forb], and Batis maritima [succulent scrub]) were created, and A. germinans propagules were emplaced into these plots and monitored over time. For comparison, propagules were also placed into natural polyculture plots (1 m2). Polyculture plots contained at least two of the salt-marsh plant taxa selected for monoculture treatments, and S. virginicus was always present within these polyculture plots. Natural polyculture plots retained 59.3% +/- 11.0% (mean +/- SE) of emplaced propagules. Monocultures varied in their propagule retention capacities with plots of S. virginicus retaining on average 65.7% +/- 11.5% of transplanted propagules compared to 7.2% +/- 1.8% by B. maritima and 5.0% +/- 1.9% by S. portulacastrum. Plots containing S. virginicus retained a significantly greater percentage of emplaced propagules relative to the two succulent salt-marsh taxa. Furthermore, propagule entrapment, across all treatments, was strongly correlated with salt-marsh structure (r2 = 0.6253, P = 0.00001), which was estimated using an indirect quantitative metric (lateral obstruction) calculated from digital images of plots. Overall, our findings imply that

  11. Production and characterization of a halo-, solvent-, thermo-tolerant alkaline lipase by Staphylococcus arlettae JPBW-1, isolated from rock salt mine.

    PubMed

    Chauhan, Mamta; Garlapati, Vijay Kumar

    2013-11-01

    Studies on lipase production and characterization were carried out with a bacterial strain Staphylococcus arlettae JPBW-1 isolated from rock salt mine, Darang, HP, India. Higher lipase activity has been obtained using 10 % inoculum with 5 % of soybean oil as carbon source utilizing a pH 8.0 in 3 h at 35 °C and 100 rpm through submerged fermentation. Partially purified S. arlettae lipase has been found to be active over a broad range of temperature (30-90 °C), pH (7.0-12.0) and NaCl concentration (0-20 %). It has shown extreme stability with solvents such as benzene, xylene, n-hexane, methanol, ethanol and toluene up to 30 % (v/v). The lipase activity has been found to be inhibited by metal ions of K(+), Co(2+) and Fe (2+) and stimulated by Mn(2+), Ca(2+) and Hg(2+). Lipase activity has been diminished with denaturants, but enhanced effect has been observed with surfactants, such as Tween 80, Tween 40 and chelator EDTA. The K m and V max values were found to be 7.05 mM and 2.67 mmol/min, respectively. Thus, the lipase from S. arlettae may have considerable potential for industrial application from the perspectives of its tolerance towards industrial extreme conditions of pH, temperature, salt and solvent. PMID:23955348

  12. The dynamics of interacting salt structures and associated fluid flow in the western Norwegian-Danish Basin

    NASA Astrophysics Data System (ADS)

    Olsen, Mikkel S.; Clausen, Ole R.; Andresen, Katrine J.; Korstgård, John A.

    2015-04-01

    Minor secondary structures observed along the flanks of major salt structures in the Norwegian-Danish Basin appear to be generated mainly during the early stages of halokinesis. Seismic anomalies in the cover sediments at the flanks of the major salt structures and in relation to one of the secondary structures show several circular patterns. The circular patterns are generally interpreted as faults related to collapsing salt, indicating a subtle and dynamic cannibalization relationship between the secondary structure and the main diapir. High-amplitude reflections interpreted as either entrapped gas along the circular faults or diagenetic changes induced by the fluids originating from the salt-sediment interface generally enhances the seismic appearance of the circular faults, but potentially also disturb the seismic imaging of the faults. Other secondary salt structures, with a similar geometry, do not show sign of collapse, apparently due to a greater distance from the main salt structures and therefore not within the reach of being cannibalized by these. The observations furthermore suggest a trend showing a more advanced development of the main salt structures when the secondary structures are cannibalized. The lateral distribution of the main salt structures thus appears to be controlled not only by the initial thickness of the Zechstein salt, and possible underlying structures, but also by subtle variations in the location and evolution of secondary structures. The secondary structures have a major impact on the drainage of the deep Mesozoic succession as indicated by the fluid flow pattern also observed in the study, which emphasizes that a detailed mapping of salt structures including secondary structures at the flanks is of major importance during evaluation of petroleum systems in areas dominated by halokinesis.

  13. Sensitivity of storage field performance to geologic and cavern design parameters in salt domes.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon; Herrick, Courtney Grant

    2010-06-01

    A sensitivity study was performed utilizing a three dimensional finite element model to assess allowable cavern field sizes in strategic petroleum reserve salt domes. A potential exists for tensile fracturing and dilatancy damage to salt that can compromise the integrity of a cavern field in situations where high extraction ratios exist. The effects of salt creep rate, depth of salt dome top, dome size, caprock thickness, elastic moduli of caprock and surrounding rock, lateral stress ratio of surrounding rock, cavern size, depth of cavern, and number of caverns are examined numerically. As a result, a correlation table between the parameters and the impact on the performance of a storage field was established. In general, slower salt creep rates, deeper depth of salt dome top, larger elastic moduli of caprock and surrounding rock, and a smaller radius of cavern are better for structural performance of the salt dome.

  14. Sensitivity of storage field performance to geologic and cavern design parameters in salt domes.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon

    2009-03-01

    A sensitivity study was performed utilizing a three dimensional finite element model to assess allowable cavern field sizes for strategic petroleum reserve salt domes. A potential exists for tensile fracturing and dilatancy damage to salt that can compromise the integrity of a cavern field in situations where high extraction ratios exist. The effects of salt creep rate, depth of salt dome top, dome size, caprock thickness, elastic moduli of caprock and surrounding rock, lateral stress ratio of surrounding rock, cavern size, depth of cavern, and number of caverns are examined numerically. As a result, a correlation table between the parameters and the impact on the performance of storage field was established. In general, slower salt creep rates, deeper depth of salt dome top, larger elastic moduli of caprock and surrounding rock, and a smaller radius of cavern are better for structural performance of the salt dome.

  15. Multiscale model for predicting shear zone structure and permeability in deforming rock

    NASA Astrophysics Data System (ADS)

    Cleary, Paul W.; Pereira, Gerald G.; Lemiale, Vincent; Piane, Claudio Delle; Clennell, M. Ben

    2016-04-01

    A novel multiscale model is proposed for the evolution of faults in rocks, which predicts their internal properties and permeability as strain increases. The macroscale model, based on smoothed particle hydrodynamics (SPH), predicts system scale deformation by a pressure-dependent elastoplastic representation of the rock and shear zone. Being a continuum method, SPH contains no intrinsic information on the grain scale structure or behaviour of the shear zone, so a series of discrete element method microscale shear cell models are embedded into the macroscale model at specific locations. In the example used here, the overall geometry and kinematics of a direct shear test on a block of intact rock is simulated. Deformation is imposed by a macroscale model where stresses and displacement rates are applied at the shear cell walls in contact with the rock. Since the microscale models within the macroscale block of deforming rock now include representations of the grains, the structure of the shear zone, the evolution of the size and shape distribution of these grains, and the dilatancy of the shear zone can all be predicted. The microscale dilatancy can be used to vary the macroscale model dilatancy both spatially and temporally to give a full two-way coupling between the spatial scales. The ability of this model to predict shear zone structure then allows the prediction of the shear zone permeability using the Lattice-Boltzmann method.

  16. Properties of Halococcus salifodinae, an Isolate from Permian Rock Salt Deposits, Compared with Halococci from Surface Waters

    PubMed Central

    Legat, Andrea; Denner, Ewald B. M.; Dornmayr-Pfaffenhuemer, Marion; Pfeiffer, Peter; Knopf, Burkhard; Claus, Harald; Gruber, Claudia; König, Helmut; Wanner, Gerhard; Stan-Lotter, Helga

    2013-01-01

    Halococcus salifodinae BIpT DSM 8989T, an extremely halophilic archaeal isolate from an Austrian salt deposit (Bad Ischl), whose origin was dated to the Permian period, was described in 1994. Subsequently, several strains of the species have been isolated, some from similar but geographically separated salt deposits. Hcc. salifodinae may be regarded as one of the most ancient culturable species which existed already about 250 million years ago. Since its habitat probably did not change during this long period, its properties were presumably not subjected to the needs of mutational adaptation. Hcc. salifodinae and other isolates from ancient deposits would be suitable candidates for testing hypotheses on prokaryotic evolution, such as the molecular clock concept, or the net-like history of genome evolution. A comparison of available taxonomic characteristics from strains of Hcc. salifodinae and other Halococcus species, most of them originating from surface waters, is presented. The cell wall polymer of Hcc. salifodinae was examined and found to be a heteropolysaccharide, similar to that of Hcc. morrhuae. Polyhydroxyalkanoate granules were present in Hcc. salifodinae, suggesting a possible lateral gene transfer before Permian times. PMID:25371342

  17. Properties of Halococcus salifodinae, an Isolate from Permian Rock Salt Deposits, Compared with Halococci from Surface Waters.

    PubMed

    Legat, Andrea; Denner, Ewald B M; Dornmayr-Pfaffenhuemer, Marion; Pfeiffer, Peter; Knopf, Burkhard; Claus, Harald; Gruber, Claudia; König, Helmut; Wanner, Gerhard; Stan-Lotter, Helga

    2013-01-01

    Halococcus salifodinae BIpT DSM 8989T, an extremely halophilic archaeal isolate from an Austrian salt deposit (Bad Ischl), whose origin was dated to the Permian period, was described in 1994. Subsequently, several strains of the species have been isolated, some from similar but geographically separated salt deposits. Hcc. salifodinae may be regarded as one of the most ancient culturable species which existed already about 250 million years ago. Since its habitat probably did not change during this long period, its properties were presumably not subjected to the needs of mutational adaptation. Hcc. salifodinae and other isolates from ancient deposits would be suitable candidates for testing hypotheses on prokaryotic evolution, such as the molecular clock concept, or the net-like history of genome evolution. A comparison of available taxonomic characteristics from strains of Hcc. salifodinae and other Halococcus species, most of them originating from surface waters, is presented. The cell wall polymer of Hcc. salifodinae was examined and found to be a heteropolysaccharide, similar to that of Hcc. morrhuae. Polyhydroxyalkanoate granules were present in Hcc. salifodinae, suggesting a possible lateral gene transfer before Permian times. PMID:25371342

  18. High and Low Salt Intake during Pregnancy: Impact on Cardiac and Renal Structure in Newborns

    PubMed Central

    Seravalli, Priscila; de Oliveira, Ivone Braga; Zago, Breno Calazans; de Castro, Isac; Veras, Mariana Matera; Alves-Rodrigues, Edson Nogueira; Heimann, Joel C.

    2016-01-01

    Introduction Previous studies from our laboratory demonstrated that dietary salt overload and salt restriction during pregnancy were associated with cardiac and renal structural and/or functional alterations in adult offspring. The present study evaluated renal and cardiac structure and the local renin-angiotensin system in newborns from dams fed high-, normal- or low-salt diets during pregnancy. Methods Female Wistar rats were fed low- (LS, 0.15% NaCl), normal- (NS, 1.3% NaCl) or high- (HS, 8% NaCl) salt diets during pregnancy. Kidneys and hearts were collected from newborns (n = 6-8/group) during the first 24 hours after birth to evaluate possible changes in structure using stereology. Protein expression of renin-angiotensin system components was evaluated using an indirect enzyme-linked immunosorbent assay (ELISA). Results No differences between groups were observed in total renal volume, volume of renal compartments or number of glomeruli. The transverse diameter of the nuclei of cardiomyocytes was greater in HS than NS males in the left and right ventricles. Protein expression of the AT1 receptor was lower in the kidneys of the LS than in those of the NS and HS males but not females. Protein expression of the AT2 receptor was lower in the kidneys of the LS males and females than in those of the NS males and females. Conclusion High salt intake during pregnancy induced left and right ventricular hypertrophy in male newborns. Salt restriction during pregnancy reduced the expression of renal angiotensin II receptors in newborns. PMID:27560182

  19. Geophysical analysis of rock glacier internal structure and implications for deformation mechanics

    NASA Astrophysics Data System (ADS)

    Florentine, C. E.; Skidmore, M. L.; Speece, M. A.; Link, C. A.; Locke, W. W.; Carr, C. G.; Shaw, C. A.

    2011-12-01

    An analysis of the internal composition and structure on the active portion of the Lone Peak Rock Glacier (LPRG), Madison range, southwest Montana revealed links between internal structure and surface topography. Seismic refraction surveys performed along transverse and longitudinal profiles corroborate borehole and excavation data by demonstrating a consistent and distinct transition from unconsolidated (unfrozen) surface debris (2-3 m thick) to a consolidated (frozen) subsurface material. Refraction velocities for the seismic survey transects were relatively consistent along their length with 400 m s-1 for the upper layer detected, and 3500 m s-1 for the lower layer detected at a depth of 2-3 m. This second velocity of 3500 m s-1 is consistent with other observed refraction velocities for ice. Ground penetrating radar (GPR) data along similar longitudinal and transverse profiles identified up-slope dipping structures to a depth of ~10 m, consistent with layering of materials with contrasting radar properties within the ice-rock unit. The GPR data is interpreted as a sequence of alternating debris-poor and debris-rich layers which dip upslope toward the rock-glacier headwall along the longitudinal profile, and which show correspondence with transverse ridges at the surface. The presence of fault bounded blocks (i.e. structural horses) detected in the longitudinal GPR data suggests passive roof duplex thrust faulting, in which the roof sequence - unconsolidated (unfrozen) debris - has not been displaced toward the foreland (down glacier), but has been underthrust by the duplex. Transverse ridges commonly characterize rock glacier surfaces in a range of locations worldwide. Approximately one third of 383 rock glaciers inventoried in southwest Montana demonstrate pronounced transverse ridges. It has previously been suggested that transverse ridges are the product of thrusting, which is caused by compressive flow in rock glaciers. Thrusting however has not been

  20. Structural Interactions within Lithium Salt Solvates: Cyclic Carbonates and Esters

    SciTech Connect

    Seo, D. M.; Afroz, Taliman; Allen, Joshua L.; Boyle, Paul D.; Trulove, Paul C.; De Long, Hugh C.; Henderson, Wesley A.

    2014-11-13

    Only limited information is available regarding the manner in which cyclic carbonate and ester solvents coordinate Li+ cations in electrolyte solutions for lithium batteries. One approach to gleaning significant insight into these interactions is to examine crystalline solvate structures. To this end, eight new solvate structures are reported with ethylene carbonate, γ-butyrolactone and γ-valerolactone: (EC)3:LiClO4, (EC)2:LiClO4, (EC)2:LiBF4, (GBL)4:LiPF6, (GBL)1:LiClO4, (GVL)1:LiClO4, (GBL)1:LiBF4 and (GBL)1:LiCF3SO3. The crystal structure of (EC)1:LiCF3SO3 is also re-reported for comparison. These structures enable the factors which govern the manner in which the ions are coordinated and the ion/solvent packing—in the solid-state—to be scrutinized in detail.

  1. Crystal structure of the catalytic domain of human bile salt activated lipase.

    PubMed Central

    Terzyan, S.; Wang, C. S.; Downs, D.; Hunter, B.; Zhang, X. C.

    2000-01-01

    Bile-salt activated lipase (BAL) is a pancreatic enzyme that digests a variety of lipids in the small intestine. A distinct property of BAL is its dependency on bile salts in hydrolyzing substrates of long acyl chains or bulky alcoholic motifs. A crystal structure of the catalytic domain of human BAL (residues 1-538) with two surface mutations (N186D and A298D), which were introduced in attempting to facilitate crystallization, has been determined at 2.3 A resolution. The crystal form belongs to space group P2(1)2(1)2(1) with one monomer per asymmetric unit, and the protein shows an alpha/beta hydrolase fold. In the absence of bound bile salt molecules, the protein possesses a preformed catalytic triad and a functional oxyanion hole. Several surface loops around the active site are mobile, including two loops potentially involved in substrate binding (residues 115-125 and 270-285). PMID:11045623

  2. Structural studies of several solvated potassium salts of tenatoprazole crystallizing as conglomerates

    NASA Astrophysics Data System (ADS)

    Tauvel, G.; Sanselme, M.; Coste-Leconte, S.; Petit, S.; Coquerel, G.

    2009-11-01

    Despite the weak acidic character of tenatoprazole it is possible to crystallize, in strong alkaline media, different solvated salts of this active pharmaceutical ingredient. Among these solid phases, some potassium salts exhibiting non congruent solubilities, form stable conglomerates in equilibrium with their mother liquors without detectable partial solid solutions between the enantiomers. The crystal structures of the ethanol and the ethylene glycol stoichiometric solvates of potassium salts have been determined by single crystal X-ray diffraction, revealing that the solvent molecules play an important role in the crystal cohesion. They participate to the coordination polyhedra of the potassium cations and also contribute to strong periodic bond chains. Moreover, there is no direct link between the tenatoprazole anions and the potassium cations, so the solvent molecules act as electrostatic relays between ions of opposite charges.

  3. Structure and ionic conductivity of block copolymer electrolytes over a wide salt concentration range

    NASA Astrophysics Data System (ADS)

    Chintapalli, Mahati; Le, Thao; Venkatesan, Naveen; Thelen, Jacob; Rojas, Adriana; Balsara, Nitash

    Block copolymer electrolytes are promising materials for safe, long-lasting lithium batteries because of their favorable mechanical and ion transport properties. The morphology, phase behavior, and ionic conductivity of a block copolymer electrolyte, SEO mixed with LiTFSI was studied over a wide, previously unexplored salt concentration range using small angle X-ray scattering, differential scanning calorimetry and ac impedance spectroscopy, respectively. SEO exhibits a maximum in ionic conductivity at twice the salt concentration that PEO, the homopolymer analog of the ion-containing block, does. This finding is contrary to prior studies that examined a more limited range of salt concentrations. In SEO, the phase behavior of the PEO block and LiTFSI closely resembles the phase behavior of homopolymer PEO and LiTFSI. The grain size of the block copolymer morphology was found to decrease with increasing salt concentration, and the ionic conductivity of SEO correlates with decreasing grain size. Structural effects impact the ionic conductivity-salt concentration relationship in block copolymer electrolytes. SEO: polystyrene-block-poly(ethylene oxide); also PS-PEO LiTFSI: lithium bis(trifluoromethanesulfonyl imide

  4. Structure of eight molecular salts assembled from noncovalent bonding between carboxylic acids, imidazole, and benzimidazole

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Zhang, Huan; Liu, Hui; Wen, Xianhong; Li, Minghui; Wang, Daqi

    2015-09-01

    Eight organic salts of imidazole/benzimidazole have been prepared with carboxylic acids as 2-methyl-2-phenoxypropanoic acid, α-ketoglutaric acid, 5-nitrosalicylic acid, isophthalic acid, 4-nitro-phthalic acid, and 3,5-dinitrosalicylic acid. The eight crystalline forms reported are proton-transfer compounds of which the crystals and compounds were characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. These structures adopted hetero supramolecular synthons, with the most common R22(7) motif observed at salts 2, 3, 5, 6 and 8. Analysis of the crystal packing of 1-8 suggests that there are extensive strong Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between acid and imidazolyl components in all of the salts. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play important roles in structure extension. This variety, coupled with the varying geometries and number of acidic groups of the acids utilized, has led to the creation of eight supramolecular arrays with 1D-3D structure. The role of weak and strong noncovalent interactions in the crystal packing is analyzed. The results presented herein indicate that the strength and directionality of the Nsbnd H⋯O, and Osbnd H⋯O hydrogen bonds between acids and imidazole/benzimidazole are sufficient to bring about the formation of organic salts.

  5. Hydration structure of salt solutions from ab initio molecular dynamics.

    PubMed

    Bankura, Arindam; Carnevale, Vincenzo; Klein, Michael L

    2013-01-01

    The solvation structures of Na(+), K(+), and Cl(-) ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na(+), K(+), and Cl(-), respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed. PMID:23298049

  6. Hydration structure of salt solutions from ab initio molecular dynamics

    SciTech Connect

    Bankura, Arindam; Carnevale, Vincenzo; Klein, Michael L.

    2013-01-07

    The solvation structures of Na{sup +}, K{sup +}, and Cl{sup -} ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na{sup +}, K{sup +}, and Cl{sup -}, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed.

  7. Hydration structure of salt solutions from ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Bankura, Arindam; Carnevale, Vincenzo; Klein, Michael L.

    2013-01-01

    The solvation structures of Na^+, K^+, and Cl^- ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na^+, K^+, and Cl^-, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed.

  8. Structure, stability and tsunami hazard associated with a rock slope in Knight Inlet, British Columbia

    NASA Astrophysics Data System (ADS)

    van Zeyl, D. P.; Stead, D.; Sturzenegger, M.; Bornhold, B. D.; Clague, J. J.

    2015-01-01

    Rockfalls and rockslides during the past 12 000 years have deposited bouldery debris cones on the seafloor beneath massive rock slopes throughout the inner part of Knight Inlet. The 885 m high rock slope situated across from the Kwalate site, a former First Nations village destroyed in the late 1500s by a slide-induced wave, exposes the contact between a Late Cretaceous dioritic pluton and metamorphic rocks of the Upper Triassic Karmutsen Formation. The pluton margin is strongly foliated in parallel with primary and secondary fabrics in the metamorphic rocks, resulting in highly persistent brittle structures. Other important structures include a set of sheeting joints and highly persistent mafic dykes and faults. Stability analysis identified the potential for planar and wedge failure. We made empirical estimates of impulse waves generated by potential slides ranging in size from 0.5 to 3.5 Mm3, with results suggesting mid-inlet wave heights in the order of 6 to 26 m. As several similar rock slopes fronted by large submarine debris cones exist in the inner part of Knight Inlet, it is clear that tsunami hazards should be considered in coastal infrastructure development and land-use planning in this area.

  9. Electronic structure and spectral-luminescent properties of 1,2,4,6-tetrasubstituted pyridinium salts

    SciTech Connect

    Korunova, A.F.; Krainov, I.P.; Protsenko, E.G.

    1985-09-01

    The structure of the electronic excitation of 1,2,4,6-tetrasubstituted pyridinium salts was studied by quantum-chemical calculations carried out by the SCF PPP CI method, using excitation-localization numbers on the atoms and fragments, and interfragmentary charge transfer numbers. The nature of the absorption bands observed in the spectra and certain structural factors causing the spectral-luminescent properties were established.

  10. Elements of Regolith Simulant's Cost Structure--Why Rock Is NOT Cheap

    NASA Technical Reports Server (NTRS)

    Rickman, Douglas L.

    2009-01-01

    The cost of lunar regolith simulants is much higher than many users anticipate. After all, it is nothing more than broken rock. This class will discuss the elements which make up the cost structure for simulants. It will also consider which elements can be avoided under certain circumstances and which elements might be altered by the application of additional research and development.

  11. Highly Shocked Low Density Sedimentary Rocks from the Haughton Impact Structure, Devon Island, Nunavut, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Spray, J. G.

    2001-01-01

    We present the preliminary results of a detailed investigation of the shock effects in highly shocked, low density sedimentary rocks from the Haughton impact structure. We suggest that some textural features can be explained by carbonate-silicate immiscibility. Additional information is contained in the original extended abstract.

  12. Lithofacies and palynostratigraphy of some Cretaceous and Paleocene rocks, Surghar and Salt Range coal fields, northern Pakistan

    USGS Publications Warehouse

    Warwick, Peter D.; Javed, Shahid; Mashhadi, S. Tahir A.; Shakoor, Tariq; Khan, Asrar M.; Khan, A. Latif

    1995-01-01

    The stratigraphic relation between the Cretaceous generally non-coal-bearing Lumshiwal Formation (64 to 150 m thick) and the Paleocene coal-bearing Hangu Formation (5 to 50 m thick) in the Surghar Range of north-central Pakistan is complex. Both formations contain remarkably similar lithofacies: one or two types of sandstone lithofacies; a combined lithofacies of mudstone, claystone, carbonaceous shale, and coal beds; and a rare carbonate lithofacies. An analysis of pollen data from rock samples collected from various stratigraphic positions indicates that the formations are separated by a disconformity and that the age of the Lumshiwal Formation is Early Cretaceous and the age of the Hangu is Paleocene. Previous workers had suggested that the age of the Lumshiwal is Late Cretaceous. An analysis of sedimentologic, stratigraphic, and paleontologic data indicates that both the Lumshiwal and Hangu Formations probably were deposited in shallow-marine and deltaic environments. The rocks of the Lumshiwal become more terrestrial in origin upward, whereas the rocks of the Hangu become more marine in origin upward. The contact between the two formations is associated with a laterally discontinuous lateritic paleosol (assigned to the Hangu Formation) that is commonly overlain by the economically important Makarwal coal bed. This coal bed averages 1.2 m in thickness. No other coal beds in the Surghar Range are as thick or as laterally continuous as the Makarwal coal bed. Analytical data from the Makarwal and one other Hangu coal bed indicate that Surghar Range coal beds range from high-volatile B to high-volatile C bituminous in apparent rank. Averaged, as-received results of proximate and ultimate analyses of coal samples are (1) moisture content, 5.4 percent; (2) ash yield, 12.5 percent; (3) total sulfur content, 5 percent; and (4) calorific value, 11034 Btu/lb (British thermal units per pound). Minor- and trace-element analyses indicate that these coals contain relatively

  13. Spectroscopic and structural investigation of oxocarbon salts with tetraalkylammonium ions

    NASA Astrophysics Data System (ADS)

    Georgopoulos, Stéfanos L.; Garcia, Humberto C.; Edwards, Howell G. M.; Cappa de Oliveira, Luiz Fernando

    2016-03-01

    In this study the synthesis, vibrational spectra (infrared and Raman) and crystal structures of three oxocarbon compounds with tetra-alkyl ammonium counter cations, namely [N(C3H7)4](HC4O4) (1), [N(C4H9)4]2[(C4O4) (H2C4O4)2] (2) and [N(C2H5)4]2(C5O5)·5H2O (3), have been reported. The supramolecular arrangement for all compounds as shown by x-ray diffraction indicate that strong donor (D)-acceptor (A) hydrogen bonds D-H…A are present in the dimer formation with monohydrogen squarate anion HC4O4- (2.503 Å) and for the trimer with two squaric acid moieties (H2C4O4) and the squarate dianion C4O42- (2.500 Å), for compounds 1 and 2, respectively. In contrast, compound 3 was stabilized through only averagely strong hydrogen bonds (2.735 Å) between all five oxygen atoms of the croconate dianion with different water molecules of crystallization of the supramolecular system. The presence of bands in the Raman spectrum at 1793 and 1670 cm-1 for compounds 1 and 2 have been assigned to the ν(Cdbnd O), ν(Cdbnd C) + ν(Cdbnd O) modes, thus confirming the oxocarbon presence in the solid structure, as well as the bands at 1716 and 1601 cm-1 for compound 3, assigned to the ν(Cdbnd O) and ν(CO) + ν(CC) + δ(CCC) + δ(CO) coupled modes of the associated croconate dianion (C5O52-). An important Raman signal observed for all structures can be seen at ca. 2950 cm-1 which is associated with the ν(CH2) and ν(CH3) stretching modes from the tetraalkylammonium cations.

  14. Ionic charge transport in strongly structured molten salts

    NASA Astrophysics Data System (ADS)

    Tatlipinar, H.; Amoruso, M.; Tosi, M. P.

    2000-02-01

    Data on the DC ionic conductivity for strongly structured molten halides of divalent and trivalent metals near freezing are interpreted as mainly reflecting charge transport by the halogen ions. On this assumption the Nernst-Einstein relation allows an estimate of the translational diffusion coefficient Dtr of the halogen. In at least one case (molten ZnCl 2) Dtr is much smaller than the measured diffusion coefficient, pointing to substantial diffusion via neutral units. The values of Dtr estimated from the Nernst-Einstein relation are analyzed on the basis of a model involving two parameters, i.e. a bond-stretching frequency ω and an average waiting time τ. With the help of Raman scattering data for ω, the values of τ are evaluated and found to mostly lie in the range 0.02-0.3 ps for a vast class of materials.

  15. Quantification of rock heterogeneities by structural geological field studies combined with laboratory analyses

    NASA Astrophysics Data System (ADS)

    Reyer, Dorothea; Afsar, Filiz; Philipp, Sonja

    2013-04-01

    Heterogeneous rock properties in terms of layering and complex infrastructure of fault zones are typical in sedimentary successions. The knowledge of in-situ mechanical rock properties is crucial for a better understanding of processes such as fracturing and fluid transport in fractured reservoirs. To estimate in situ rock properties at different depths it is important to understand how rocks from outcrops differ from rocks at depth, for example due to alteration and removal of the overburden load. We aim at quantifying these properties by performing structural geological field studies in outcrop analogues combined with laboratory analyses of outcrop samples and drill-cores. The field studies focus on 1) fault zone infrastructure and 2) host rock fracture systems in two different study areas with different lithologies, the North German and the Bristol Channel Basin. We analyse quantitatively the dimension, geometry, persistence and connectivity of fracture systems. The field studies are complemented by systematic sampling to obtain the parameters Young's modulus, compressive and tensile strengths and elastic strain energy (also referred to as destruction work) from which we estimate rock and fracture toughnesses. The results show that in rocks with distinctive layering fractures are often restricted to individual layers, that is, stratabound. The probability of arrest seems to depend on the stiffness contrast between two single layers as well as on the thickness of the softer layer. The results also show that there are clear differences between fault zones in the different lithologies in terms of damage zone thicknesses and fracture system parameters. The results of laboratory analyses show that the mechanical properties vary considerably and for many samples there are clear directional differences. That is, samples taken perpendicular to layering commonly have higher stiffnesses and strengths than those taken parallel to layering. We combine the results of

  16. Optical and electron transport properties of rock-salt Sc{sub 1−x}Al{sub x}N

    SciTech Connect

    Deng, Ruopeng; Zheng, P. Y.; Gall, D.

    2015-07-07

    Epitaxial single-crystal Sc{sub 1−x}Al{sub x}N ternary alloy layers deposited by magnetron co-sputtering on MgO(001) substrates at 950 °C exhibit a solid solution rock-salt phase for x = 0–0.2 without decomposition. Optical absorption indicates a linear increase in the optical gap from 2.51 eV for ScN to 3.05 eV for Sc{sub 0.8}Al{sub 0.2}N and, after correction due to the Moss-Burstein shift, a direct X point interband transition energy E{sub g}(X) = 2.15 + 2.75 x (eV). Correspondingly, the direct transition at the zone center increases with Al concentration according to E{sub g}(Γ) = 3.80 + 1.45 x (eV), as determined from a feature in the reflection spectra. All layers are degenerate n-type semiconductors with a room temperature mobility that decreases from 22 to 6.7 to 0.83 cm{sup 2}/V s as x increases from 0 to 0.11 to 0.20. The corresponding carrier densities are 9.2 × 10{sup 20}, 7.9 × 10{sup 20}, and 0.95 × 10{sup 20 }cm{sup −3} as determined from Hall measurements and consistent with optical free carrier absorption below photon energies of 1 eV. Temperature dependent transport measurements indicate metallic conduction for ScN, but weak localization that leads to a resistivity minimum at 85 and 210 K for x = 0.051 and 0.15, respectively, and a negative temperature coefficient over the entire measured 4–300 K range for Sc{sub 0.8}Al{sub 0.2}N. The decreasing mobility is attributed to alloy scattering at randomly distributed Al atoms on cation sites, which also cause the weak localization. The carrier density is primarily due to unintentional F doping from the Sc target and decreases strongly for x > 0.15, which is attributed to trapping in defect states due to the deterioration of the crystalline quality, as evidenced by the x-ray diffraction peak width that exhibits a minimum of 0.14° for x = 0.11 but increases to 0.49° for x = 0.20. This is consistent with asymmetric x

  17. Rebar corrosion monitoring in concrete structure under salt water enviroment using fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Pan, Yuheng; Liu, Tiegen; Jiang, Junfeng; Liu, Kun; Wang, Shuang; He, Pan; Yan, Jinlin

    2015-08-01

    Monitoring corrosion of steel reinforcing bars is critical for the durability and safety of reinforced concrete structures. Corrosion sensors based on fiber optic have proved to exhibit meaningful benefits compared with the conventional electric ones. In recent years, Fiber Bragg Grating (FBG) has been used as a new kind of sensing element in an attempt to directly monitor the corrosion in concrete structure due to its remarkable advantages. In this paper, we present a novel kind of FBG based rebar corrosion monitoring sensor. The rebar corrosion is detected by volume expansion of the corroded rebar by transferring it to the axial strain of FBG when concrete structure is soaked in salt water. An accelerated salt water corrosion test was performed. The experiment results showed the corrosion can be monitored effectively and the corrosion rate is obtained by volume loss rate of rebar.

  18. Structural and aggregate analyses of (Li salt + glyme) mixtures: the complex nature of solvate ionic liquids.

    PubMed

    Shimizu, Karina; Freitas, Adilson A; Atkin, Rob; Warr, Gregory G; FitzGerald, Paul A; Doi, Hiroyuki; Saito, Soshi; Ueno, Kazuhide; Umebayashi, Yasuhiro; Watanabe, Masayoshi; Canongia Lopes, José N

    2015-09-14

    The structure and interactions of different (Li salt + glyme) mixtures, namely equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide, nitrate or trifluoroacetate salts combined with either triglyme or tetraglyme molecules, are probed using Molecular Dynamics simulations. structure factor functions, calculated from the MD trajectories, confirmed the presence of different amounts of lithium-glyme solvates in the aforementioned systems. The MD results are corroborated by S(q) functions derived from diffraction and scattering data (HEXRD and SAXS/WAXS). The competition between the glyme molecules and the salt anions for the coordination to the lithium cations is quantified by comprehensive aggregate analyses. Lithium-glyme solvates are dominant in the lithium bis(trifluoromethylsulfonyl)imide systems and much less so in systems based on the other two salts. The aggregation studies also emphasize the existence of complex coordination patterns between the different species (cations, anions, glyme molecules) present in the studied fluid media. The analysis of such complex behavior is extended to the conformational landscape of the anions and glyme molecules and to the dynamics (solvate diffusion) of the bis(trifluoromethylsulfonyl)imide plus triglyme system. PMID:26245295

  19. Preliminary Descriptions of Impact Rocks Recovered by Recent Core Drilling in the Manson Impact Structure

    NASA Astrophysics Data System (ADS)

    Anderson, R. R.; Witzke, B. J.; Hartung, J. B.

    1993-07-01

    In a recent drilling program 12 cores totaling over 1200 m were recovered from the Manson Impact Structure. Four principal impact rock types were encountered (1) Sedimentary Clast Breccia (SCB), (2) Crystalline Clast Breccia with Sandy Matrix (CCB-S) and Melt Rock Matrix (CCB-M), (3) Central Peak Igneous and Metamorphic Rocks (CP), and (4) an overturned flap of Impact Ejecta (IE). The SCB is dominated by clasts of Cretaceous marine shale and mudstone, with subordinate Cretaceous sandstones, Paleozoic carbonates, minor Proterozoic Red Clastics, and rare crystalline rock and impact melt-rock clasts in a medium gray, calcareous, sandy shale matrix. Parallel deformation features (PDFs) and other evidence of impact metamorphism are extremely rare. The SCB reaches a maximum thickness in excess of 200 m and is interpreted as a post-impact debris flow that originated at the crater margins. The abundance, large clasts (up to 75 m) and pervasive occurrence of SCB (cored in all regions of the Manson Impact Structure including the Central Peak pit) suggests a high energy emplacement mechanism, possibly water rushing into the crater following an impact in a shallow marine environment. The uppermost unit on the Central Peak, the CCB-M, displays abundant clasts, dominated by quartz grains, most displaying PDFs, shock isotropism, and/or partial melting. Some clasts display accretionary mantling by melt materials, apparently while airborne, with subsequent mixing into the CCB-M. An isotropic melt matrix frequently displays flow-banding and devitrification textures. The CCB-M is interpreted as an impact melt layer, derived primarily from crystalline basement rocks, and may represent CCB-S that experienced sufficient heat to melt the matrix grains. A central zone of the CCB-M displays clusters of sanidine crystals, recrystalized from impact melt in a region that apparently cooled more slowly. The CCB-S is dominated by clasts of basement gneiss and granite in a matrix of sand- to silt

  20. Crystal Structure of a Coiled-Coil Domain from Human ROCK I

    PubMed Central

    Tu, Daqi; Li, Yiqun; Song, Hyun Kyu; Toms, Angela V.; Gould, Christopher J.; Ficarro, Scott B.; Marto, Jarrod A.; Goode, Bruce L.; Eck, Michael J.

    2011-01-01

    The small GTPase Rho and one of its targets, Rho-associated kinase (ROCK), participate in a variety of actin-based cellular processes including smooth muscle contraction, cell migration, and stress fiber formation. The ROCK protein consists of an N-terminal kinase domain, a central coiled-coil domain containing a Rho binding site, and a C-terminal pleckstrin homology domain. Here we present the crystal structure of a large section of the central coiled-coil domain of human ROCK I (amino acids 535–700). The structure forms a parallel α-helical coiled-coil dimer that is structurally similar to tropomyosin, an actin filament binding protein. There is an unusual discontinuity in the coiled-coil; three charged residues (E613, R617 and D620) are positioned at what is normally the hydrophobic core of coiled-coil packing. We speculate that this conserved irregularity could function as a hinge that allows ROCK to adopt its autoinhibited conformation. PMID:21445309

  1. Assessing the disturbed rock zone (DRZ) around a 655 meter vertical shaft in salt using ultrasonic waves: An update

    SciTech Connect

    HARDY,ROBERT D.; HOLCOMB,DAVID J.

    2000-03-14

    An array of ultrasonic transducers was constructed consisting of three identical arrays at various depths in an air intake shaft at the Waste Isolation Pilot Plant (WIPP). Each array consists of transducers permanently installed in three holes arranged in an L shape. An active array, created by appropriate arrangement of the transducers and selection of transmitter-receiver pairs, allows the measurement of transmitted signal velocities and amplitudes (for attenuation studies) along 216 paths parallel, perpendicular and tangential to the shaft walls. Transducer positions were carefully surveyed, allowing absolute velocity measurements. Installation occurred over a period of about two years beginning in early 1989, with nearly continuous operation since that time, resulting in a rare, if not unique, record of the spatial and temporal variability of damage development around an underground opening. This paper reports results from the last two years of operation, updating the results reported by Holcomb, 1999. Results will be related to the damage, due to microcracking, required to produce the observed changes. It is expected that the results will be useful to other studies of the long-term deformation characteristics of salt.

  2. Evidence for a Meteoritic Component in Impact Melt Rock from the Chicxulub Structure

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Sharpton, Virgil L.; Schuraytz, Benjamin C.; Shirey, Steven B.; Blum, Joel D.; Marin, Luis E.

    1994-01-01

    The Chicxulub structure in Yucatan, Mexico, has recently been recognized as a greater then 200-km-diameter multi-ring impact crater of K-T boundary age. Crystalline impact melt rocks and breccias from within the crater, which have compositions similar to those of normal continental crustal rocks and which show shock metamorphic effects, have been studied for trace element and Re-Os isotope compositions. Re-Os isotope systematics allow the sensitive and selective determination of an extraterrestrial component in impact-derived rocks. A melt rock sample shows elevated iridium concentrations, an osmium concentration of 25 ppb, and a low Os-187/Os-188 ratio of 0.113, which are incompatible with derivation from the continental crust. Even though the Os-187/Os-188 ratio is slightly lower than the range so far measured in meteorites, a mantle origin seems unlikely for mass balance reasons and because the cratering event is unlikely to have excavated mantle material. The data support the hypothesis of a heterogeneously distributed meteoritic component in the Chicxulub melt rock. A sample of impact glass from the Haitian K-T boundary at Beloc yielded about 0.1 ppb osmium and an Os-187/0s-188 ratio of 0.251, indicating the presence of a small meteoritic component in the impact ejecta as well.

  3. Diagenetic facies controls on pore structure and rock electrical parameters in tight gas sandstone

    NASA Astrophysics Data System (ADS)

    Liu, Hongping; Zhao, Yanchao; Luo, Yang; Chen, Zhaoyou; He, Sheng

    2015-08-01

    Rock electrical parameters of tight gas sandstone show large variations in the T2 member in Dingbei Block, Ordos Basin, China. Applying the same rock electrical parameters in water saturation calculations would lead to large errors. Based on casting thin sections, x-ray diffraction, scanning electron microscopy (SEM), cathode luminescence, porosity and permeability, image analysis, and high-pressure mercury intrusion/withdrawal method, identification of the diagenetic facies are first conducted, and then their pore structure and their relationship with rock electrical parameters are investigated. Five diagenetic facies (A-E), which are identified based mainly on pore types and authigenic minerals, have different pore structure and rock electrical parameters. Conceptual models that incorporate the rock properties of each diagenetic facies have been built, before applying the electrical efficiency theory to explain the values of cementation exponent (m) and saturation exponent (n). A conventional network model, a shunt pore model, a netted pore model, and a dotted line model are utilized to mimic the intergranular pores, authigenic kaolinite intercrystal pores, carbonate-cement dissolution pores, and clay-matrix intercrystal pores, respectively. A decrease of the contents of large pores increases electrical efficiency and therefore reduces m. The saturation exponent, which depends on the distribution of water and gas, can be better understood by applying the different pore models. In the shunt and netted pore models, gas displacement starts from the larger pores and smaller pores provide alternative conduction pathways, hence sustaining electrical efficiency and decreasing n. Clay-matrix intercrystal pores are mainly micropores, since the brine in the rocks are isolated after gas displacement, reducing overall electrical efficiency and dramatically increasing the value of n in the diagenetic facies, which is dominated by clay-matrix intercrystal pores.

  4. Reverse Polarity Magnetized Melt Rocks from the Cretaceous/Tertiary Chicxulub Structure, Yucatan Peninsula, Mexico

    NASA Technical Reports Server (NTRS)

    Urrutia-Fucugauchi, J.; Marin, Luis; Sharpton, Virgil L.

    1994-01-01

    We report paleomagnetic results for core samples of the breccia and andesitic rocks recovered from the Yucatan-6 Petrolcos Mexicanos exploratory well within the Chicxulub structure (about 60 km SSW from its center), northern Yucatan, Mexico. A previous study has shown that the rocks studied contain high iridium levels and shocked breccia clasts and an Ar/Ar date of 65.2 +/- 0.4 Ma. Andesitic rocks are characterized by stable single-component magnetizations with a mean inclination of -42.6 deg +/- 2.4 deg. Breccias present a complex paleomagnetic record characterized by multivectorial magnetizations with widely different initial NRM inclinations. However, after alternating field demagnetization, well defined characteristic components with upward inclinations are defined. IRM acquisition experiments, comparison of IRM and NRM coercivity spectra and the single component magnetization of the andesitic rocks indicate the occurrence of iron-rich titanomagnetites of single or pseudo-single domain states as the dominant magnetic carriers. Mean inclinations from the andesitic rocks and most of the breccia samples give a mean inclination of about -40 deg to -45 deg, indicating a reverse polarity for the characteristic magnetization that is consistent with geomagnetic chron 29R, which spans the Cretaceous/Tertiary (K/T) boundary. The inclination is also consistent with the expected value (and corresponding paleolatitude) for the site estimated from the reference polar wander curve for North America. We suggest that the characteristic magnetizations for the andesitic and breccia rocks are the result of shock heating at the time of formation of the impact structure and that the age, polarity and pateolatitude are consistent with a time at the K/T boundary.

  5. Petrography, geochemistry, and alteration of country rocks from the Bosumtwi impact structure, Ghana

    NASA Astrophysics Data System (ADS)

    Karikari, Forson; Ferrière, Ludovic; Koeberl, Christian; Reimold, Wolf Uwe; Mader, Dieter

    Samples of the country rocks that likely constituted the target rocks at the 1.07 Myr old Bosumtwi impact structure in Ghana, West Africa, collected outside of the crater rim in the northern and southern parts of the structure, were studied for their petrographic characteristics and analyzed for their major- and trace-element compositions. The country rocks, mainly meta-graywacke, shale, and phyllite of the Early Proterozoic Birimian Supergroup and some granites of similar age, are characterized by two generations of alteration. A pre-impact hydrothermal alteration, often along shear zones, is characterized by new growth of secondary minerals, such as chlorite, sericite, sulfides, and quartz, or replacement of some primary minerals, such as plagioclase and biotite, by secondary sericite and chlorite. A late, argillic alteration, mostly associated with the suevites, is characterized by alteration of the melt/glass clasts in the groundmass of suevites to phyllosilicates. Suevite, which occurs in restricted locations to the north and to the south-southwest of the crater rim, contains melt fragments, diaplectic quartz glass, ballen quartz, and clasts derived from the full variety of target rocks. No planar deformation features (PDFs) in quartz were found in the country rock samples, and only a few quartz grains in the suevite samples show PDFs, and in rare cases two sets of PDFs. Based on a total alkali element-silica (TAS) plot, the Bosumtwi granites have tonalitic to quartz-dioritic compositions. The Nb versus Y and Ta versus Yb discrimination plots show that these granites are of volcanic-arc tectonic provenance. Provenance studies of the metasedimentary rocks at the Bosumtwi crater have also indicated that the metasediments are volcanic-arc related. Compared to the average siderophile element contents of the upper continental crust, both country rocks and impact breccias of the Bosumtwi structure show elevated siderophile element contents. This, however, does not

  6. The impact of salt tectonics on supra-salt (Lago Mare?) deposits and on the structural evolution of the Cyprus-Eratosthenes collision zone

    NASA Astrophysics Data System (ADS)

    Reiche, Sönke; Hübscher, Christian; Ehrhardt, Axel

    2015-04-01

    Averagely 1.5 km thick Messinian evaporites laterally continue from the Levant Basin, easternmost Mediterranean Sea, into the collision zone between Cyprus and Eratosthenes Seamount where incipient continent-continent-collision is believed to occur. In this study, the impact of Messinian evaporites on the structural evolution of the collision zone is investigated for the first time based on a comprehensive set of seismic reflection profiles. Results show that the collision zone may be subdivided into an eastern and a western domain. In the eastern part, bordered by Eratosthenes Seamount and the Hecataeus Rise, compressionally thickened autochthonous salt is observed. Sub- and supra-salt deposits within this area appear to be in the stage of active accretion. Further west, between Cyprus and Eratosthenes Seamount strongly deformed allochthonous salt has evidently started to advance across sediments of post-Messinian age. In this domain, previously active sediment accretion at the Cyprus margin has now become inactive and shortening is largely accommodated at the leading edge of the allochthonous salt sheet. Such observations bear important implications for the structural interrelation between salt tectonics and the evolution of a young collision zone. On top of highly deformed mobile Messinian evaporites, up to 700 m thick late Messinian supra-salt deposits are mapped within the western part of the Cyprus - Eratosthenes collision zone. Their uppermost 200 m were drilled in the course of ODP Leg 160 (Site 968) and interpreted as Lago Mare sediments, deposited during the final stage of the Messinian Salinity Crisis (Robertson, 1998). These sediments occupy small sub-basins flanked by salt diapirs, indicating a salt-tectonic control on late Messinian sediment deposition. Distribution of these sediments may have further been controlled by sea-level, inferred from rapid eastward thinning and pinchout of Messinian supra-salt deposits towards the Levant Basin

  7. Nano-structured Pt embedded in acidic salts of heteropolymolybdate matrices: MS EXAFS study

    NASA Astrophysics Data System (ADS)

    Witkowska, Agnieszka; Dsoke, Sonia; Marassi, Roberto; Di Cicco, Andrea

    2015-12-01

    A structural study of Pt nano-catalysts is presented in the paper. The innovation in the case of the considered catalytic materials resides in the use a meso-microporous inorganic matrix of heteropolyacid salt of composition X2.5H0.5YMo12O40 where X = Rb, Cs and Y = P, Si as a catalyst support. Metallic nanoparticles were created by platinum ions reduction in a hot H2/Argon stream and were mainly located into matrix pores. As the porous structure can be controlled by the type and content of the cation used, the desired/optimal Pt nanoparticle size can be precisely defined by using a proper heteropolyacid salt composition. Multiple-scattering extended X-ray absorption fine structure (MS EXAFS) analysis was applied to obtain the relation between the matrix composition and the size of the catalyst nanoparticles. The results showed that it was only the secondary structure form of the heteropolymolybdate salt (i.e. Rb or Cs cations) that influenced the metallic nanoparticle size. The smaller the X atom ionic radii, the larger the mean diameter of the embedded Pt nanoparticles.

  8. Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    NASA Technical Reports Server (NTRS)

    Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.

    2005-01-01

    Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

  9. Effect of pore structure on seismic rock-physics characteristics of dense carbonates

    NASA Astrophysics Data System (ADS)

    Pan, Jian-Guo; Wang, Hong-Bin; Li, Chuang; Zhao, Jian-Guo

    2015-03-01

    The Ordovician carbonate rocks of the Yingshan formation in the Tarim Basin have a complex pore structure owing to diagenetic and secondary structures. Seismic elastic parameters (e.g., wave velocity) depend on porosity and pore structure. We estimated the average specific surface, average pore-throat radius, pore roundness, and average aspect ratio of carbonate rocks from the Tazhong area. High P-wave velocity samples have small average specific surface, small average pore-throat radius, and large average aspect ratio. Differences in the pore structure of dense carbonate samples lead to fluid-related velocity variability. However, the relation between velocity dispersion and average specific surface, or the average aspect ratio, is not linear. For large or small average specific surface, the pore structure of the rock samples becomes uniform, which weakens squirt flow and minimizes the residuals of ultrasonic data and predictions with the Gassmann equation. When rigid dissolved (casting mold) pores coexist with less rigid microcracks, there are significant P-wave velocity differences between measurements and predictions.

  10. Structural investigation of brittle carbonate fault rocks at various scales: implications for fluid migration

    NASA Astrophysics Data System (ADS)

    Schröckenfuchs, Theresa-Christina; Bauer, Helene; Decker, Kurt; Grasemann, Bernhard

    2013-04-01

    The EW-striking, sinistral Salzach-Ennstal-Mariazell-Puchberg fault system is a prominent feature in the Northern Calcareous Alps (NCA) in Austria. In particular, within the eastern part of the NCA, in Styria, it creates characteristic fault rocks in carbonates, comparable to fault rocks from similar tectonic regimes in other areas. Furthermore, faults and their characteristic fault rocks in this area play an important role in groundwater filtering, fluid pathways and in initiating karstification; this is of great social and economic importance since most of the drinking water for Vienna is obtained from that area. The fault zones are therefore ideal for investigating reservoir properties such as porosity and permeability evolution. Since detailed studies of such fault rocks on a micro scale are still rare, this work focuses on investigating structures and processes that create typical features in carbonate fault rocks from field- to nano-scale. Additionally, reservoir properties have been characterized. Apart from detailed structural field-work and porosity and permeability-measurements in the laboratory, thin-sections were analysed by optical microscopy, cathodoluminescence microscopy and electron microscopy using backscattered electron pictures and focused ion-beam techniques. The analytical methods provide an insight on processes and features such as grain size reduction, cementation and recrystallization, and point out porosity and permeability differences due to deformation mechanisms and cementation events. The results show that besides the common theory of grain interaction (rotation, gliding), in situ grain size reduction, predominantly controlled by pore fluid, plays an important role in creating cataclastic fabrics. Microscopic observations reveal a high amount of matrix porosity in dolomitic fault-core rocks, such as cataclasites and dilation breccias, which explains the high porosity values for those rocks measured in the laboratory; generally

  11. Accessory and opaque minerals in impact melt rocks of the Boltysh structure, Ukraine

    NASA Astrophysics Data System (ADS)

    Gurov, E. P.; Shekhunova, S. B.; Permyakov, V. V.

    2015-06-01

    Electron microprobe analyses of accessory and opaque minerals from the impact melt rocks of the Boltysh structure, in the central part of the Ukrainian Shield, are presented in this report. Our study establishes a variety of minerals represented by native metals, alloys, oxides, sulfides, phosphates, and silicates, formed during several stages of cooling and solidification of the thick impact melt sheet. Baddeleyite was determined to be the earliest high-temperature mineral to occur in the impact melt rocks. Iron and titanium oxides crystallized earlier or simultaneously with the microliths of orthopyroxene and feldspars. High concentrations of TiO2, Al2O3, and Cr2O3 were identified in some hematite varieties. Cu- and Ni-bearing pyrrhotites occur in impact melt rocks with a glassy matrix. Native metals—copper, platinum, and silver—were likely formed due to the hydrothermal alteration of the upper unit of the impact melt sheet. Zircon is the only accessory mineral found in impact melt rocks that is preserved from the basement granites of the Boltysh structure.

  12. Effect of salt and surfactant concentration on the structure of polyacrylate gel/surfactant complexes.

    PubMed

    Nilsson, Peter; Unga, Johan; Hansson, Per

    2007-09-20

    Small-angle X-ray scattering was used to elucidate the structure of crosslinked polyacrylate gel/dodecyltrimethylammonium bromide complexes equilibrated in solutions of varying concentrations of surfactant and sodium bromide (NaBr). Samples were swollen with no ordering (micelle free), or they were collapsed with either several distinct peaks (cubic Pm3n) or one broad correlation peak (disordered micellar). The main factor determining the structure of the collapsed complexes was found to be the NaBr concentration, with the cubic structure existing up to approximately 150 mM NaBr and above which only the disordered micellar structure was found. Increasing the salt concentration decreases the polyion mediated attractive forces holding the micelles together causing swelling of the gel. At sufficiently high salt concentration the micelle-micelle distance in the gel becomes too large for the cubic structure to be retained, and it melts into a disordered micellar structure. As most samples were above the critical micelle concentration, the bulk of the surfactant was in the form of micelles in the solution and the surfactant concentration thereby had only a minor influence on the structure. However, in the region around 150 mM NaBr, increasing the surfactant concentration, at constant NaBr concentration, was found to change the structure from disordered micellar to ordered cubic and back to disordered again. PMID:17715959

  13. Spiropyran salts and their neutral precursors: synthesis, crystal structure, photochromic transformations in solutions and solid state

    NASA Astrophysics Data System (ADS)

    Yurieva, E. A.; Aldoshin, S. M.

    2015-06-01

    This review covers investigations of spiropyran iodides with N-substituted indoline fragment, and with the pyran cycle being annelated to N-methylated pyridine ring. The schemes of synthesis of iodides and their neutral precursors, as well as results of X-ray analysis and photochemical study of the crystals of the obtained compounds are presented. Based on our and literature data, the relationship between the structure and photochromic properties has been discussed for a series of salts and neutral pyridospiropyrans.

  14. Construction of heterocyclic structures by trivalent cerium salts promoted bond forming reactions.

    PubMed

    Properzi, Roberta; Marcantoni, Enrico

    2014-02-01

    Cerium(III) salts have recently gained increasing attention in the synthetic community, owing to the powerful features that are reviewed in detail in this tutorial. This review reports significant examples of cerium(III) promoted synthesis of heterocyclic structures, initially dealing with the synthesis of five- and six-membered ring nitrogen containing heterocycles, then describing the preparation of their oxygenated analogues and finally discussing the achievement of seven-membered rings and mixed heterocyclic motifs. PMID:24217370

  15. Introducing improved structural properties and salt dependence into a coarse-grained model of DNA

    SciTech Connect

    Snodin, Benedict E. K. Mosayebi, Majid; Schreck, John S.; Romano, Flavio; Doye, Jonathan P. K.; Randisi, Ferdinando; Šulc, Petr; Ouldridge, Thomas E.; Tsukanov, Roman; Nir, Eyal; Louis, Ard A.

    2015-06-21

    We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na{sup +}] = 0.5M), so that it can be used for a range of salt concentrations including those corresponding to physiological conditions. Finally, we use new experimental data to parameterise the oxDNA potential so that consecutive adenine bases stack with a different strength to consecutive thymine bases, a feature which allows a more accurate treatment of systems where the flexibility of single-stranded regions is important. We illustrate the new possibilities opened up by the updated model, oxDNA2, by presenting results from simulations of the structure of large DNA objects and by using the model to investigate some salt-dependent properties of DNA.

  16. The internal geometry of salt structures - A first look using 3D seismic data from the Zechstein of the Netherlands

    NASA Astrophysics Data System (ADS)

    Van Gent, Heijn; Urai, Janos L.; de Keijzer, Martin

    2011-03-01

    We present a first look at the large-scale, complexly folded and faulted internal structure of Zechstein salt bodies in NW Europe using 3D reflection seismic reflection data from two surveys on the Groningen High and the Cleaver Bank High. We focus on a relatively brittle, folded and boudinaged, claystone-carbonate-anhydrite layer (the Z3 stringer) enclosed in ductile salt. A first classification of the structures is presented and compared with observations from salt mines and analogue and numerical models. Z3 stringers not only are reservoirs for hydrocarbons but can also present a serious drilling problem in some areas. Results of this study could provide the basis for better prediction of zones of drilling problems. More generally, the techniques presented here can be used to predict the internal structure of salt bodies, to estimate the geometry of economic deposits of all kinds and locate zones suitable for storage caverns. Structures observed include an extensive network of zones with increased thickness of the stringer. These we infer to have formed by early diagenesis, karstification, gravitational sliding and associated local sedimentation. Later, this template was deformed into large-scale folds and boudins during salt tectonics. Salt flow was rarely plane strain, producing complex fold and boudin geometries. Deformation was further complicated by the stronger zones of increased thickness, which led to strongly non-cylindrical structures. We present some indications that the thicker zones also influence the locations of later suprasalt structures, suggesting a feedback between the early internal evolution of this salt giant and later salt tectonics. This study opens the possibility to study the internal structure of the Zechstein and other salt giants in 3D using this technique, exposing a previously poorly known structure which is comparable in size and complexity to the internal parts of some orogens.

  17. Structural characterization of Turtle Mountain anticline (Alberta, Canada) and impact on rock slope failure

    NASA Astrophysics Data System (ADS)

    Humair, Florian; Pedrazzini, Andrea; Epard, Jean-Luc; Froese, Corey R.; Jaboyedoff, Michel

    2013-10-01

    This paper proposes a structural investigation of the Turtle Mountain anticline (Alberta, Canada) to better understand the role of the different tectonic features on the development of both local and large scale rock slope instabilities occurring in Turtle Mountain. The study area is investigated by combining remote methods with detailed field surveys. In particular, the benefit of Terrestrial Laser Scanning for ductile and brittle tectonic structure interpretations is illustrated. The proposed tectonic interpretation allows the characterization of the fracturing pattern, the fold geometry and the role of these tectonic features in rock slope instability development. Ten discontinuity sets are identified in the study area, their local variations permitting the differentiation of the study zone into 20 homogenous structural domains. The anticline is described as an eastern verging fold that displays considerable geometry differences along its axis and developed by both flexural slip and tangential longitudinal strain folding mechanisms. Moreover, the origins of the discontinuity sets are determined according to the tectonic phases affecting the region (pre-folding, folding, post-folding). The localization and interpretation of kinematics of the different instabilities revealed the importance of considering the discrete brittle planes of weakness, which largely control the kinematic release of the local instabilities, and also the rock mass damage induced by large tectonic structures (fold hinge, thrust).

  18. Relationships between watershed emergy flow and coastal New England salt marsh structure, function, and condition.

    PubMed

    Brandt-Williams, Sherry; Wigand, Cathleen; Campbell, Daniel E

    2013-02-01

    This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI, USA. The field-collected data were obtained during several years of vegetation, invertebrate, soil, and water quality sampling. The use of emergy as an accounting mechanism allowed disparate factors (e.g., the amount of building construction and the consumption of electricity) to be combined into a single landscape index while retaining a uniform quantitative definition of the intensity of landscape development. It expanded upon typical land use percentage studies by weighting each category for the intensity of development. At the RI salt marsh sites, an impact index (watershed emergy flow normalized for marsh area) showed significant correlations with mudflat infauna species richness, mussel density, plant species richness, the extent and density of dominant plant species, and denitrification potential within the high salt marsh. Over the 4-year period examined, a loading index (watershed emergy flow normalized for watershed area) showed significant correlations with nitrite and nitrate concentrations, as well as with the nitrogen to phosphorus ratios in stream discharge into the marshes. Both the emergy impact and loading indices were significantly correlated with a salt marsh condition index derived from intensive field-based assessments. Comparison of the emergy indices to calculated nitrogen loading estimates for each watershed also produced significant positive correlations. These results suggest that watershed emergy flow is a robust index of human disturbance and a potential tool for rapid assessment of coastal wetland condition. PMID:22535367

  19. Response of Soil Fungi Community Structure to Salt Vegetation Succession in the Yellow River Delta.

    PubMed

    Wang, Yan-Yun; Guo, Du-Fa

    2016-10-01

    High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation (saline seepweed, Angiospermae, Imperata and Apocynum venetum [A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities (Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities (saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture (r = 0.985; P < 0.01). Soil quality, salt vegetation and soil fungi were influenced by each other. PMID:27449214

  20. Thickness and internal structure of relict rock glaciers - a challenge for geophysics: Examples from two rock glaciers in the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas; Pauritsch, Marcus; Morawetz, Rainer; Kuehnast, Birgit; Schreilechner, Marcellus; Winkler, Gerfried

    2014-05-01

    Knowledge of thickness and internal structure of relict rock glaciers is generally sparse but key factors for their storage capacity and thus their impact on the alpine water cycle. In this study we present results of geophysical measurements carried out at two neighboring rock glaciers located in the Seckauer Tauern Range, Austria. Both rock glaciers have been considered originally as relict. The Schöneben Rock Glacier (SRG) is a monomorphic rock glacier covering an area of 0.11km², has a length of 750 m, a width of up to 200 m and ranges from 1720-1905 m a.s.l. The Reichart Rock Glacier (RRG) is a large polymorphic rock glacier with two main source areas covering an area of 1.26 km², and ranges from 1520-1920 m a.s.l.. The landform has a length of 1860 m and a maximum width of c.1600 m. Both rock glaciers consist predominantly of coarse-grained, blocky gneissic sediments at the surface. At SRG ground penetrating radar (GPR) and seismic refraction (SR) was applied thereby profiling the entire rock glacier. GPR was carried out at ten profiles (two longitudinal profiles and eight cross profiles) with a total length of 3235 m. SR was applied at three profiles (one longitudinal profile and two cross profiles) with a total length of 1259 m. Seismic energy was generated by using a sledge hammer as well as blastings near the surface. At RRG electrical resistivity tomography (ERT) and SR has been applied. One 340 m long SR cross profile was accomplished close to the rock glacier front. Furthermore, one 120 m long ERT longitudinal profile was measured starting from the upper part of the rooting zone of RRG and ending within the talus slope above the rock glacier. Generally SR data clearly indicate the boundary between sediments and bedrock for both rock glaciers. Seismic P-wave velocities range between 550 and 900 m/s for the near-surface debris layer, between 1370 and 1880 m/s for deeper sediments layers (possibly due water saturated, fine-grained sediments), and

  1. Seismic response of rock slopes: Numerical investigations on the role of internal structure

    NASA Astrophysics Data System (ADS)

    Arnold, L.; Applegate, K.; Gibson, M.; Wartman, J.; Adams, S.; Maclaughlin, M.; Smith, S.; Keefer, D. K.

    2013-12-01

    The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project Seismically-Induced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bonded-particle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a non-linear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from sub-horizontal to sub-vertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF

  2. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    PubMed

    Hudait, Arpa; Molinero, Valeria

    2014-06-01

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  3. Salt tectonics and gravity driven deformation: Structural guidelines for exploration in passive margin

    SciTech Connect

    Mauduit, T.; Gwenael G.; Brun, J.P.

    1995-08-01

    The West African Margin, (Gulf of Guinea) presents spectacular examples of gravity driven deformation above a salt decollement (i.e. growth faulting, rafts, diapirs and contractional structures) which have been documented by numerous Oil and Gas investigations. Seismic data demonstrate that the variation of deformation styles in space and time appear to be function of: regional geometry of the margin (i.e. value of basal slope and presence/absence of residual reliefs below the salt layers) and, mode, rate and repartition of sedimentation. The role and effects of the above parameters were analyzed using laboratory modeling investigation based on basic structural patterns identified through seismic data. Models are built with sand and silicone putty, that respectively represent the frictional behavior of upper Cretaceous-Cenozoic cover and the viscous behavior of the upper Aptian salt. They are scaled to fit observed natural configurations. Results are compared with examples from the Gulf of Guinea on the basis of seismic data. This approach allowed to better understand the evolution of the margin and therefore the reservoir distributions and traps geometries.

  4. An Investigation Into Vortioxetine Salts: Crystal Structure, Thermal Stability, and Solubilization.

    PubMed

    He, Sai-Fei; Zhang, Xian-Rui; Zhang, Shuo; Guan, Su; Li, Jing; Li, Shan; Zhang, Lei

    2016-07-01

    Three 1:1 salts containing vortioxetine (VOT), an orally antidepressant drug, and 3 aryl monoacids have been designed and successfully prepared by liquid-assisted grinding based on the ΔpKa rule. The C-O bond lengths (∼1.25 Å) in the COOH groups show that the proton transfer has occurred from aryl monoacid to piperazine N1 atom of vortioxetine in the crystal structures. Three salts feature cyclic [2 + 2] structural units through R(4)4 (12) N-H···O hydrogen bonding interactions which result in the remarkable thermal stabilities, and VOT-p-aminobenzoic acid shows 2-dimensional framework by linking cyclic [2 + 2] units through additional hydrogen bonding interactions. The equilibrium solubility of VOT in VOT-p-aminobenzoic acid salt can be largely improved up to 0.50 mg/mL (about 450% above the free base) at 25°C in water, which also accelerates the intrinsic dissolution rate. PMID:27262207

  5. AFM Studies of Salt Concentration Effects on the (110) Surface Structure of Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Pusey, Marc Lee; Gorti, Sridhar; Forsythe, Elizabeth; Konnert, John

    2002-01-01

    Previous high resolution AFM studies of the (110) surface of tetragonal chicken egg white lysozyme crystals had shown that only one of two possible molecular surfaces is present, those constituting the completed 43 helices. These suggested that the crystal growth process was by the solution-phase assembly of the growth units, which then attach to the surface. However, the best fit for the imaged surfaces, vs. those predicted based upon the bulk crystallographic coordinates, were obtained when the packing about the 43 helices was "tightened up", while maintaining the underlying crystallographic unit cell spacing. This results in a widening of the gap between adjacent helices, and the top- most layer(s) may no longer be in contact. We postulated that the tightened packing about the helices is a result of the high salt concentrations in the bulk solution, used to crystallize the protein, driving hydrophobic interactions. Once the crystal surface is sufficiently buried by subsequent growth layers the ratio of salt to protein molecules decreases and the helices relax to their bulk crystallographic coordinates. The crystal surface helix structure is thus a reflection of the solution structure, and the tightness of the packing about the 43 helices would be a function of the bulk salt concentration. AFM images of the (110) surface of tetragonal lysozyme crystals grown under low (2%) and high (5%) NaCl concentrations reveal differences in the packing about the 43 helices consistent with the above proposal.

  6. Seismic evaluation of rocking structures through performance assessment and fragility analysis

    NASA Astrophysics Data System (ADS)

    Vetr, Mohammad G.; Nouri, Abolfazl Riahi; Kalantari, Afshin

    2016-03-01

    Numerical studies have been conducted for low- and medium-rise rocking structures to investigate their efficiency as earthquake-resisting systems in comparison with conventional structures. Several non-linear time-history analyses have been performed to evaluate seismic performance of selected cases at desired ground shaking levels, based on key parameters such as total and flexural story drifts and residual deformations. The Far-field record set is selected as input ground motions and median peak values of key parameters are taken as best estimates of system response. In addition, in order to evaluate the probability of exceeding relevant damage states, analytical fragility curves have been developed based on the results of the incremental dynamic analysis procedure. Small exceedance probabilities and acceptable margins against collapse, together with minor associated damages in main structural members, can be considered as superior seismic performance for medium-rise rocking systems. Low-rise rocking systems could provide significant performance improvement over their conventional counterparts notwithstanding certain weaknesses in their seismic response.

  7. Observation of pseudo-two-dimensional electron transport in the rock salt-type topological semimetal LaBi

    NASA Astrophysics Data System (ADS)

    Kumar, Nitesh; Shekhar, Chandra; Wu, Shu-Chun; Leermakers, Inge; Young, Olga; Zeitler, Uli; Yan, Binghai; Felser, Claudia

    2016-06-01

    Topological insulators are characterized by an inverted band structure in the bulk and metallic surface states on the surface. In LaBi, a semimetal with a band inversion equivalent to a topological insulator, we observe surface-state-like behavior in the magnetoresistance. The electrons responsible for this pseudo-two-dimensional transport, however, originate from the bulk states rather topological surface states, which is witnessed by the angle-dependent quantum oscillations of the magnetoresistance and ab initio calculations. As a consequence, the magnetoresistance exhibits strong anisotropy with large amplitude (˜105%) .

  8. Salt-dependent structure change and ion binding in cytochrome c studied by two-dimensional proton NMR

    SciTech Connect

    Feng, Yiqing; Englander, S.W. )

    1990-04-10

    To search for salt-dependent structure changes that might help to explain physicochemical differences observed in previous solution studies, two-dimensional proton NMR spectra of reduced and oxidized cytochrome c were recorded at relatively high and low salt concentrations. The results rule out substantial ionic strength dependent structure change in either redox form over the salt concentrations tested. Chemical shift changes were found for several residues within a limited segment of the oxidized protein, most prominently in the sequence Lys-86, Lys-87, Lys-88, Thr-89. A salt-dependent binding of phosphate anion(s) at this site, as observed earlier by others, is indicated. The binding of one or two phosphates at the cytochrome c surface can explain earlier small-angle X-ray scattering observations of an increase in the calculated radius of gyration of the oxidized protein at the same low-salt condition used here. The results obtained support the view that the absence of sizeable redox-dependent structure change observed in X-ray and NMR studies at varying salt conditions is characteristic of the protein at all salt conditions above the low millimolar range. Physicochemical differences between oxidized and reduced cytochrome c apparently represent differences in stability without patent structure change.

  9. Collaborative Research: Evolution of Pore Structure and Permeability of Rocks Under Hydrothermal Conditions

    SciTech Connect

    Zhu, Wenlu; Evans, J. Brian

    2007-04-15

    The physical and transport properties of porous rocks can be altered by a variety of diagenetic, metamorphic, and tectonic processes, and the changes that result are of critical importance to such industrial applications as resource recovery, carbon dioxide sequestration, and waste isolation in geologic formations. These inter-relationships between rocks, pore fluids, and deformation are also the key to understanding many natural processes, including: dynamic metamorphism, fault mechanics, fault stability, and pressure solution deformation. Here, we propose work to investigate the changes of permeability and pore geometry owing to inelastic deformation by solution-transfer, brittle fracturing, and dislocation creep. The work would study the relationship of deformation and permeability reduction in fluid-filled quartz and calcite rocks and investigate the effects of loading configuration on the evolution of porosity and permeability under hydrothermal conditions. We would use a combination of techniques, including laboratory experiments, numerical calculations, and observations of rock microstructure. The laboratory experiments provide mechanical and transport data under conditions that isolate each particular mechanism. Our apparatus are designed to provide simultaneous measurements of pore volume, permeability, axial and volumetric strain rates while being loaded under isostatic or conventional triaxial loading. Temperatures up to 1400 K may be obtained, while confining pressures and pore pressures are maintained independently up to 500 MPa. Observations of the structure will be made with standard optical, scanning electron, and laser confocal scanning optical microscopes. The data obtained will be used to quantify changes in surface roughness, porosity, pore dimensions, and their spatial fluctuations. The results of the experiments and the image data are then used in network, finite-difference and other numerical models to verify the validity of experimentally

  10. Structural relationships of pre-Tertiary rocks in the Nevada Test Site region, southern Nevada

    SciTech Connect

    Cashman, P.H.; Cole, J.C.

    1999-08-30

    This report summarizes the evidence for a revised interpretation of major structural features in the pre-Tertiary rocks of the region including and surrounding the Nevada Test Site. The thick miogeoclinal section of Late Proterozoic through Lower Permian sedimentary strata records major foreland-vergent thrust faulting, younger hinterland-vergent folding and thrusting, and local extension on low-angle normal faults. In addition, structural discontinuities in the northeastern part of the Nevada Test Site strongly suggest a broad, north-trending zone of sinistral strike-slip faulting that may have had a cumulative offset of many kilometers.

  11. Structural relationships of pre-Tertiary rocks in the Nevada Test Site region, southern Nevada

    USGS Publications Warehouse

    Cole, James C.; Cashman, Patricia Hughes

    1999-01-01

    This report contains a synthesis and interpretation of structural and stratigraphic data for pre-Tertiary rocks in a large area of southern Nevada within and near the Nevada Test Site. Its presents descriptive and interpretive information from discontinuously exposed localities in the context of a regional model that integrates stratigraphy, sedimentology, crustal structure, and deformational style and timing. Evidence is given for substantial strike-slip faults, for modest excursion on low-angle faults, and for pre-Oligocene formation of the regional oroclinal flexure in neighboring mountain ranges.

  12. Pentaglyme-K salt binary mixtures: phase behavior, solvate structures, and physicochemical properties.

    PubMed

    Mandai, Toshihiko; Tsuzuki, Seiji; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi

    2015-01-28

    We prepared a series of binary mixtures composed of certain K salts (KX) and pentaglyme (G5) with different salt concentrations and anionic species ([X](-): [(CF3SO2)2N](-) = [TFSA](-), [CF3SO3](-) = [TfO](-), [C4F9SO3](-) = [NfO](-), PF6(-), SCN(-)), and characterized them with respect to their phase diagrams, solvate structures, and physicochemical properties. Their phase diagrams and thermal stability strongly implied the formation of equimolar complexes. Single-crystal X-ray crystallography was performed on certain equimolar complexes, which revealed that G5 molecules coordinate to K(+) cations in a characteristic manner, like 18-crown-6 ether in the crystalline state, irrespective of the paired anions. The solvate structures in the molten state were elucidated by a combination of temperature-dependent Raman spectroscopy and X-ray crystallography. A drastic spectral variation was observed in the [K(G5)1][TfO] Raman spectra, indicating that solvate structures in the crystalline state break apart upon melting. The solvate stability of [K(G5)1]X is closely related to the ion-ion interaction of the parent salts. A stable solvate forms when the ion-dipole interaction between K(+) and G5 overwhelms the ion-ion interaction between K(+) and X(-). Furthermore, the physicochemical properties of certain equimolar mixtures were evaluated. A Walden plot clearly reflects the ionic nature of the molten equimolar complexes. Judging from the structural characteristics and dissociativity, we classified [K(G5)1]X into two groups, good and poor solvate ionic liquids. PMID:25501925

  13. Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

    USGS Publications Warehouse

    Declercq, J.; Dypvik, H.; Aagaard, P.; Jahren, J.; Ferrell, R.E., Jr.; Horton, J. Wright, Jr.

    2009-01-01

    The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

  14. Domal structure in Devonian rocks of Kimberling basin, Bland County, Virginia

    SciTech Connect

    McDowell, R.C.

    1988-08-01

    The Kimberling basin, which is floored with Middle Devonian clastic rocks, is a topographic and structural low in the Narrows fault block of the southern Appalachian Valley and Ridge province in Bland County, Virginia. The basin is bounded on the northwest and southeast by the southeast-dipping Narrows and Saltville thrust faults, respectively. Two doubly plunging anticlines lie along the strike of the basin. Lower Ordovician rocks are exposed in the Burkes Garden dome to the southwest, and Lower Cambrian rocks are present in the core of the Bane dome to the northeast. Previous workers have postulated continuity between the Burkes Garden and Bane domes through the Kimberling basin, as well as the presence in the basin of an anomalously thick Devonian clastic section, which has been ascribed by some authors to contemporaneous downwarp of a depositional syncline. Recent mapping has shown both of these postulates to be incorrect. The basin contains an anticline-syncline pair that is en echelon with the axes of the Burkes Garden and Bane anticlines and that trends about 20/degree/ more northerly than the regional strike of the bounding thrusts. Rediscovery of small outcrops of Lower and Middle Devonian Huntersville Chert and Rocky Gap Sandstone in the core of the Kimberling basin anticline, which were recorded by M.R. Campbell in 1896 but overlooked by later mappers, shows that the Devonian clastic sequence has a normal thickness and that the Kimberling basin contains a domal structure similar to the Burkes Garden and Bane domes.

  15. Genetic structural provinces and salt tectonics of the Cenozoic offshore US Gulf of Mexico: A preliminary analysis

    SciTech Connect

    Peel, F.J.; Travis, C.J.; Hossack, J.R.

    1996-12-31

    Structures in the Cenozoic section of the U.S. Gulf of Mexico margin are thin-skinned, gravity-driven, and powered by the deposition of sediment on the shelf and upper slope. Deformation driven by sedimentation takes the form of salt displacement (including diapirism, salt withdrawal, and salt canopy formation), plus seaward gravity spreading and sliding. Lateral flow of salt gives rise to the emplacement of large-scale salt canopies of different ages. Lateral tectonic movement of both sediment and salt results in linked systems on a wide range of scales. We identify four structural provinces that contain distinct groups of structural elements believed to be genetically related: (1) far-eastern Gulf, in which no major Cenozoic deformation is seen; (2) eastern Gulf, defined mainly by a middle-late Miocene linked system of extension and contraction; (3) central Gulf, in which Oligocene updip extension was absorbed within a preexisting giant salt canopy; and (4) western Gulf, defined by several Paleogene-middle Miocene linked systems of extension and contraction. The ages and extents of each linked system match the major foci of sediment input to the shelf.

  16. Synthesis of rock-salt type lithium borohydride and its peculiar Li{sup +} ion conduction properties

    SciTech Connect

    Miyazaki, R.; Maekawa, H.; Takamura, H.

    2014-05-01

    The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH{sub 4,} known for its super Li{sup +} ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH{sub 4}, more suitable to the high rate condition. We synthesized the H.P. form of LiBH{sub 4} under ambient pressure by doping LiBH{sub 4} with the KI lattice by sintering. The formation of a KI - LiBH{sub 4} solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li{sup +} conductor despite its small Li{sup +} content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the “Parasitic Conduction Mechanism.” This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  17. Distribution of siderophile and other trace elements in melt rock at the Chicxulub impact structure

    NASA Technical Reports Server (NTRS)

    Schuraytz, B. C.; Lindstrom, D. J.; Martinez, R. R.; Sharpton, V. L.; Marin, L. E.

    1994-01-01

    Recent isotopic and mineralogical studies have demonstrated a temporal and chemical link between the Chicxulub multiring impact basin and ejecta at the Cretaceous-Tertiary boundary. A fundamental problem yet to be resolved, however, is identification of the projectile responsible for this cataclysmic event. Drill core samples of impact melt rock from the Chichxulub structure contain Ir and Os abundances and Re-Os isotopic ratios indicating the presence of up to approx. 3 percent meteoritic material. We have used a technique involving microdrilling and high sensitivity instrumental neutron activation analysis (INAA) in conjunction with electron microprobe analysis to characterize further the distribution of siderophile and other trace elements among phases within the C1-N10 melt rock.

  18. Solvation structure around the Li(+) ion in succinonitrile-lithium salt plastic crystalline electrolytes.

    PubMed

    Shen, Yuneng; Deng, Gang-Hua; Ge, Chuanqi; Tian, Yuhuan; Wu, Guorong; Yang, Xueming; Zheng, Junrong; Yuan, Kaijun

    2016-06-01

    Herein, we discuss the study of solvation dynamics of lithium-succinonitrile (SN) plastic crystalline electrolytes by ultrafast vibrational spectroscopy. The infrared absorption spectra indicated that the CN stretch of the Li(+) bound and unbound succinonitrile molecules in a same solution have distinct vibrational frequencies (2276 cm(-1)vs. 2253 cm(-1)). The frequency difference allowed us to measure the rotation decay times of solvent molecules bound and unbound to Li(+) ion. The Li(+) coordination number of the Li(+)-SN complex was found to be 2 in the plastic crystal phase (22 °C) and 2.5-3 in the liquid phase (80 °C), which is independent of the concentration (from 0.05 mol kg(-1) to 2 mol kg(-1)). The solvation structures along with DFT calculations of the Li(+)-SN complex have been discussed. In addition, the dissociation percentage of lithium salt was also determined. In 0.5 mol kg(-1) LiBF4-SN solutions at 80 °C, 60% ± 10% of the salt dissociates into Li(+), which is bound by 2 or 3 solvent molecules. In the 0.5 mol kg(-1) LiClO4-SN solutions at 80 °C, the salt dissociation ratio can be up to 90% ± 10%. PMID:27189266

  19. Long-term cement corrosion in chloride-rich solutions relevant to radioactive waste disposal in rock salt - Leaching experiments and thermodynamic simulations

    NASA Astrophysics Data System (ADS)

    Bube, C.; Metz, V.; Bohnert, E.; Garbev, K.; Schild, D.; Kienzler, B.

    Low- and intermediate-level radioactive wastes are frequently solidified in a cement matrix. In a potential repository for nuclear wastes, the cementitious matrix is altered upon contact with solution and the resulting secondary phases may provide for significant retention of the radionuclides incorporated in the wastes. In order to assess the secondary phases formed upon corrosion in chloride-rich solutions, which are relevant for nuclear waste disposal in rock salt, leaching experiments were performed. Conventional laboratory batch experiments using powdered hardened cement paste in MgCl2-rich solutions were left to equilibrate for up to three years and full-scale cemented waste products were exposed to NaCl-rich and MgCl2-rich solutions for more than twenty years, respectively. Solid phase analyses revealed that corrosion of hardened cement in MgCl2-rich solutions advanced faster than in NaCl-rich solutions due to the extensive exchange of Mg from solution against Ca from the cementitious solid. Thermodynamic equilibrium simulations compared well to results at the final stages of the respective experiments indicating that close to equilibrium conditions were reached. At high cement product to brine ratios (>0.65 g mL-1), the solution composition in the laboratory-scale experiments was close to that of the full-scale experiments (cement to brine ratio of 2.5 g mL-1) in the MgCl2 systems. The present study demonstrates the applicability of thermodynamic methods used in this approach to adequately describe full-scale long-term experiments with cemented waste simulates.

  20. Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

    NASA Technical Reports Server (NTRS)

    Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

    1993-01-01

    Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

  1. Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

    NASA Astrophysics Data System (ADS)

    Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

    1993-03-01

    Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

  2. Numerical analysis of the performance of rock weirs: Effects of structure configuration on local hydraulics

    USGS Publications Warehouse

    Holmquist-Johnson, C. L.

    2009-01-01

    River spanning rock structures are being constructed for water delivery as well as to enable fish passage at barriers and provide or improve the aquatic habitat for endangered fish species. Current design methods are based upon anecdotal information applicable to a narrow range of channel conditions. The complex flow patterns and performance of rock weirs is not well understood. Without accurate understanding of their hydraulics, designers cannot address the failure mechanisms of these structures. Flow characteristics such as jets, near bed velocities, recirculation, eddies, and plunging flow govern scour pool development. These detailed flow patterns can be replicated using a 3D numerical model. Numerical studies inexpensively simulate a large number of cases resulting in an increased range of applicability in order to develop design tools and predictive capability for analysis and design. The analysis and results of the numerical modeling, laboratory modeling, and field data provide a process-based method for understanding how structure geometry affects flow characteristics, scour development, fish passage, water delivery, and overall structure stability. Results of the numerical modeling allow designers to utilize results of the analysis to determine the appropriate geometry for generating desirable flow parameters. The end product of this research will develop tools and guidelines for more robust structure design or retrofits based upon predictable engineering and hydraulic performance criteria. ?? 2009 ASCE.

  3. Physical analog (centrifuge) model investigation of contrasting structural styles in the Salt Range and Potwar Plateau, northern Pakistan

    NASA Astrophysics Data System (ADS)

    Faisal, Shah; Dixon, John M.

    2015-08-01

    We use scaled physical analog (centrifuge) modeling to investigate along- and across-strike structural variations in the Salt Range and Potwar Plateau of the Himalayan foreland fold-thrust belt of Pakistan. The models, composed of interlayered plasticine and silicone putty laminae, comprise four mechanical units representing the Neoproterozoic Salt Range Formation (basal detachment), Cambrian-Eocene carapace sequence, and Rawalpindi and Siwalik Groups (Neogene molasse), on a rigid base representing the Indian craton. Pre-cut ramps simulate basement faults with various structural geometries. A pre-existing north-dipping basement normal fault under the model foreland induces a frontal ramp and a prominent fault-bend-fold culmination, simulating the Salt Range. The ramp localizes displacement on a frontal thrust that occurs out-of-sequence with respect to other foreland folds and thrusts. With a frontal basement fault terminating to the east against a right-stepping, east-dipping lateral ramp, deformation propagates further south in the east; strata to the east of the lateral ramp are telescoped in ENE-trending detachment folds, fault-propagation folds and pop-up structures above a thick basal detachment (Salt Range Formation), in contrast to translated but less-deformed strata with E-W-trending Salt-Range structures to the west. The models are consistent with Salt Range-Potwar Plateau structural style contrasts being due to basement fault geometry and variation in detachment thickness.

  4. Effects of Crowder Structure and Salt on DNA Mobility and Conformation in Crowded Environments

    NASA Astrophysics Data System (ADS)

    Gorczyca, Stephanie M.; Robertson-Anderson, Rae M.

    Biological cells are crowded environments in which DNA must move through to perform specific functions. We study how the properties of crowded cell-like environments impact DNA dynamics by tracking individual 115 kbp ring and linear DNA in different crowded environments using single-molecule fluorescence microscopy. We determine the role of crowder structure and salt on DNA diffusion and conformation by measuring the mean-squared center-of-mass displacements, as well as the conformational shape, size, and fluctuations of each molecule. Previously, we used 10 and 500 kDa dextran as crowders and showed that mobility of both ring and linear DNA decreased exponentially with increased crowding, but rings compact while linear DNA elongate. These effects were dependent solely on the reduction in available volume for DNA rather than size or number of crowders. Here we use crowders of similar molecular weight, but different structure to dextran (10 kDa PEG and 400 kDa Ficoll). We find that DNA mobility reduction is independent of crowder structure and that ring and linear DNA undergo more significant compaction. Finally, we characterize the role of salt on DNA mobility and conformation to determine the relative roles of enthalpic versus entropic effects on crowding-induced DNA dynamics. This research was funded by the AFOSR Young Investigator Program, Grant No. FA95550-12-1-0315 and the Arnold and Mabel Beckman Scholarship Foundation.

  5. The study of crystal structures and vibrational spectra of inorganic salts of 2,4-diaminopyrimidine

    NASA Astrophysics Data System (ADS)

    Matulková, Irena; Mathauserová, Jana; Císařová, Ivana; Němec, Ivan; Fábry, Jan

    2016-01-01

    Six novel salts of 2,4-diaminopyrimidine were prepared and studied by X-ray single-crystal structure analysis and vibrational spectroscopy. All but one of the title compounds, i.e. (2,4-diaminopyrimidine) 2,4-diaminopyrimidinium perchlorate, 2,4-diaminopyrimidinium nitrate, 2,4-diaminopyrimidinium perchlorate, bis(2,4-diaminopyrimidinium) hydrogen phosphate tetrahydrate and bis(2,4-diaminopyrimidinium) selenate dihydrate, crystallize in the triclinic system with the centrosymmetric space group P 1 bar while the crystals of the remaining compound - 2,4-diaminopyrimidinium chloride hemihydrate - belong to the monoclinic system (space group C2/c). All the crystal structures contain the characteristic graph set motif R22 (8) with N-H… N hydrogen bonds. This graph set motif can be formed by one of three possible arrangements of a pair of 2,4-diaminopyrimidinium cations and all these arrangements have been observed in the title structures. The title salts were also investigated by vibrational spectroscopy (FTIR and FT Raman). The presented interpretation of the vibrational spectra is based on DFT calculations of 2,4-diaminopyrimidine molecule and 2,4-diaminopyrimidinium cation.

  6. Salt-induced gelation of globular protein aggregates: structure and kinetics.

    PubMed

    Ako, Komla; Nicolai, Taco; Durand, Dominique

    2010-04-12

    Aggregates of the globular protein beta-lactoglobulin were formed by heating solutions of native proteins at pH 7, after which gels were formed by the addition of salt. The second step does not necessitate elevated temperatures and is therefore often called cold gelation. The structure of the gels was studied during their formation using light scattering and turbidity. Complementary confocal laser scanning microscopy measurements were done. We compared the structure with that of gels formed by heating native beta-lactoglobulin under the same conditions. Whereas in the latter case, microphase separation occurs above 0.2 M NaCl, no microphase separation was observed during cold gelation up to at least 1 M NaCl. The dependence of the kinetics and the final gel structure on the protein concentration, the temperature, the salt concentration, and the aggregate size was quantified. A few measurements on gels formed by adding CaCl(2) confirmed the higher efficiency of this bivalent cation but revealed no qualitative differences with gels formed by adding NaCl. PMID:20297835

  7. Shallow Structure of the Eagle Rock and Raymond Faults in Arroyo Seco, Los Angeles County, California

    NASA Astrophysics Data System (ADS)

    Scheirer, D. S.; Rymer, M. J.; Catchings, R. D.; Goldman, M.; Fuis, G.

    2012-12-01

    To understand the location, dip, and possible structural connection of the Eagle Rock and Raymond faults in Pasadena and South Pasadena, California, we acquired and analyzed high-resolution seismic reflection and refraction data, as well as gravity observations, along the floor of the Arroyo Seco. The studies were conducted to aid in understanding the seismic hazards of these faults in this urban setting. Seismic reflection and refraction data, including both P-wave and S-wave records, were collected along two profiles, a 1.2-km-long northern profile crossing the Eagle Rock fault, and a 450-m-long southern profile crossing the Raymond fault. Seismic sources were Betsy-Seisgun shots, accelerated weight drops, and repeated sledge-hammer impacts, which were recorded on multi-channel seismograph systems connected to vertical- and horizontal-component geophones spaced at a 5-m interval. Gravity data were collected along a single ~3-km-long profile coincident with and extending beyond and between the two seismic profiles, with stations spaced every 25-m near the fault traces and at greater intervals farther from the fault traces. We carefully accounted for the gravity effects of the adjacent concrete drainage channel and of the walls of the arroyo, to generate gravity anomalies that reflect sub-surface density contrasts across the Eagle Rock and Raymond faults. Seismic reflection image quality is compromised by the highly-deformed Miocene strata offset by these faults. However, reflection and especially refraction results indicate that both the Eagle Rock and Raymond faults consist of multiple, steeply-north-dipping fault strands. P- and S-wave seismic tomography results of the uppermost 50-100 m yield velocity variations that can be converted to probable density variations, and thus be included in the gravity anomaly analysis. The gravity anomalies predicted from the velocity variations account for less than one-third of the anomalies observed across the faults

  8. Hydraulic properties and inner structure of a relict rock glacier in the Eastern Alps, Austria

    NASA Astrophysics Data System (ADS)

    Pauritsch, Marcus; Winkler, Gerfried; Kellerer-Pirklbauer, Andreas; Birk, Steffen

    2013-04-01

    Water economic studies in 1990s documented the importance of the springs draining relict rock glaciers for water supply and human consumption as well as for the ecosystem in alpine catchments in the Niederen Tauern Range, Austria. Recent studies confirm the hydrologic importance and show that in the easternmost subunit, the Seckauer Tauern Range, more than 40% of the area above 2000 m a.s.l. and up to 20% of the area above 1500 m a.s.l. drain through relict rock glaciers. Thus, the hydraulic properties of these alpine aquifers are considered to be important controls on the hydrology of these areas. Nevertheless their hydraulic properties and their inner structure are still poorly understood. Our hydrogeological research is carried out at the Schöneben Rock Glacier, located in Seckauer Tauern Range, Austria. This rock glacier is presumably relict although patches of permafrost might exist particularly in the upper part of the landform. The rock glacier covers an area of 0.11 km² and drains a total catchment of 0.76 km² with a maximum elevation of 2282 m a.s.l.. The rock glacier consists predominantly of gneissic sediments (mainly coarse-grained, blocky at the surface) and extends from 1720 to 1905 m a.s.l.. Discharge of the rock glacier spring is recorded since 2002. Electrical conductivity and water temperature used as natural tracers are continuously monitored since 2008. Furthermore, a tracer test with simultaneous injection of the fluorescent dyes naphthionate and fluoresceine at two injection points (one close to the front and one close to the rooting zone of the rock glacier) was performed. Recession analysis of the spring hydrograph reveals similarities to the flow dynamics of karst springs. The results exhibit on the one hand a slow base flow recession indicating a high storage capacity and on the other hand sharp discharge peaks immediately after rainfall events referring to a high hydraulic conductivity. Applying different analytic runoff models, the

  9. Abating corrosion in highway structures due to sea or deicing salts

    NASA Astrophysics Data System (ADS)

    Kessler, Rick J.; Powers, Rodney G.

    1995-05-01

    Corrosion of steel reinforcing bars in concrete bridge structures due to the intrusion of chloride ions from seawater or de-icing salts affects many structures in the nation's highway system. Over the past decade cathodic protection has evolved as a promising technology for arresting corrosion. The development of materials, equipment, and methods for applying cathodic protection is in a dynamic state. Through cooperative efforts with academia, industry, and the engineering community, the Florida Deparment of Transportation has developed several innovative corrosion protection systems which incorporate technologies from a wide variety of specialty areas including telemetry, photovoltaics, polymers, and specialty components developed as part of the national defense program. This paper provides an overview of corrosion and cathodic protection technology and focuses on the potential for adaptation of existing technologies into preservation of highway bridge structures.

  10. Application of the hard and soft acids and bases concept to explain ligand coordination in double salt structures

    NASA Astrophysics Data System (ADS)

    Balarew, Christo; Duhlev, Rumen

    1984-11-01

    The coordination polyhedra in 43 double salt structures are examined. Each structure is formed by at least two kinds of polyhedra. The differences in the environment around the metal ions are explained using HSAB concept. The values of hardness for 25 cations are calculated according to Klopman. A factor χ = Hacid· Hbase, where H is the hardness value, is introduced. The value of this factor can be used as a criterion for the stability of the complexes. The possibilities which the χ factor gives in explaining ligand coordination in known structures as well as for predicting structures for double salts are illustrated.

  11. Geochemical Study of Rocks from the Kentland, Indiana, Impact Structure: Progress Report

    NASA Astrophysics Data System (ADS)

    Koeberl, C.; Sharpton, V. L.

    1993-07-01

    The Kentland impact structure is situated about 4 km east of the town of Kentland, Newton County, Indiana, at 40 degrees x 45'N and 87 degrees x 24'W. With a diameter of about 12.5 km, it is one of the larger impact structures preserved in the U.S. Quarry operations have exposed various Ordovician and Silurian rocks near the center of the structure. Almost all bedrocks are covered by Pleistocene glacial till. The crater shows a central structural uplift of about 4 km diameter with an intensely disturbed area of about 1 km diameter at the center. The uplift involves rocks from a preimpact stratigraphic depth of at least 600 m [1]. The uplift is surrounded by a circular depression 1.5 to 2 km wide, followed by a structural high, about 6.2 km from the center, that is assumed to be the present-day outer limit of the structure. Geophysical studies indicate a gravity high in the center (coinciding with the structural uplift) with an encircling gravity low marking the ring depression. For the origin of the Kentland structure, various endogenic hypotheses were proposed earlier, but over the past 2-3 decades meteorite impact has been established as the most likely origin. Various forms of shock metamorphism have been documented from the structure (mainly well-preserved shatter cones, shock deformed mineral grains, and monomict as well as polymict breccias). Monomict breccias often occur mainly in carbonate rocks, but some are also found in sandy units. Polymict breccias are more abundant and exposed in quarries. They contain mainly dolomite, calcite, chert, and shale clasts (size range millimeters to 0.5 m) with quartz grains and occasional shatter-cone fragments. The matrix of the breccias is hard and comprises light gray, fine- grained carbonate material. We have started a combined geochemical and petrographical study of breccias from the Kentland structure in order to define geochemical relationships between breccias and source rocks and search for a possible

  12. Structural and functional analysis of transmembrane segment IV of the salt tolerance protein Sod2.

    PubMed

    Ullah, Asad; Kemp, Grant; Lee, Brian; Alves, Claudia; Young, Howard; Sykes, Brian D; Fliegel, Larry

    2013-08-23

    Sod2 is the plasma membrane Na(+)/H(+) exchanger of the fission yeast Schizosaccharomyces pombe. It provides salt tolerance by removing excess intracellular sodium (or lithium) in exchange for protons. We examined the role of amino acid residues of transmembrane segment IV (TM IV) ((126)FPQINFLGSLLIAGCITSTDPVLSALI(152)) in activity by using alanine scanning mutagenesis and examining salt tolerance in sod2-deficient S. pombe. Two amino acids were critical for function. Mutations T144A and V147A resulted in defective proteins that did not confer salt tolerance when reintroduced into S. pombe. Sod2 protein with other alanine mutations in TM IV had little or no effect. T144D and T144K mutant proteins were inactive; however, a T144S protein was functional and provided lithium, but not sodium, tolerance and transport. Analysis of sensitivity to trypsin indicated that the mutations caused a conformational change in the Sod2 protein. We expressed and purified TM IV (amino acids 125-154). NMR analysis yielded a model with two helical regions (amino acids 128-142 and 147-154) separated by an unwound region (amino acids 143-146). Molecular modeling of the entire Sod2 protein suggested that TM IV has a structure similar to that deduced by NMR analysis and an overall structure similar to that of Escherichia coli NhaA. TM IV of Sod2 has similarities to TM V of the Zygosaccharomyces rouxii Na(+)/H(+) exchanger and TM VI of isoform 1 of mammalian Na(+)/H(+) exchanger. TM IV of Sod2 is critical to transport and may be involved in cation binding or conformational changes of the protein. PMID:23836910

  13. Structure of a Highly Conserved Domain of Rock1 Required for Shroom-Mediated Regulation of Cell Morphology

    PubMed Central

    Bauer, Robert J.; Heroux, Annie; Zalewski, Jenna K.; Heber, Simone; Dosunmu-Ogunbi, Atinuke M.; Trakselis, Michael A.; Hildebrand, Jeffrey D.; VanDemark, Andrew P.

    2013-01-01

    Rho-associated coiled coil containing protein kinase (Rho-kinase or Rock) is a well-defined determinant of actin organization and dynamics in most animal cells characterized to date. One of the primary effectors of Rock is non-muscle myosin II. Activation of Rock results in increased contractility of myosin II and subsequent changes in actin architecture and cell morphology. The regulation of Rock is thought to occur via autoinhibition of the kinase domain via intramolecular interactions between the N-terminus and the C-terminus of the kinase. This autoinhibited state can be relieved via proteolytic cleavage, binding of lipids to a Pleckstrin Homology domain near the C-terminus, or binding of GTP-bound RhoA to the central coiled-coil region of Rock. Recent work has identified the Shroom family of proteins as an additional regulator of Rock either at the level of cellular distribution or catalytic activity or both. The Shroom-Rock complex is conserved in most animals and is essential for the formation of the neural tube, eye, and gut in vertebrates. To address the mechanism by which Shroom and Rock interact, we have solved the structure of the coiled-coil region of Rock that binds to Shroom proteins. Consistent with other observations, the Shroom binding domain is a parallel coiled-coil dimer. Using biochemical approaches, we have identified a large patch of residues that contribute to Shrm binding. Their orientation suggests that there may be two independent Shrm binding sites on opposing faces of the coiled-coil region of Rock. Finally, we show that the binding surface is essential for Rock colocalization with Shroom and for Shroom-mediated changes in cell morphology. PMID:24349032

  14. Recent Enhancements to the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Cabell, Randolph H.; Allen, Albert R.

    2013-01-01

    The Structural Acoustics Loads and Transmission (SALT) facility at the NASA Langley Research Center is comprised of an anechoic room and a reverberant room, and may act as a transmission loss suite when test articles are mounted in a window connecting the two rooms. In the latter configuration, the reverberant room acts as the noise source side and the anechoic room as the receiver side. The noise generation system used for qualification testing in the reverberant room was previously shown to achieve a maximum overall sound pressure level of 141 dB. This is considered to be marginally adequate for generating sound pressure levels typically required for launch vehicle payload qualification testing. Recent enhancements to the noise generation system increased the maximum overall sound pressure level to 154 dB, through the use of two airstream modulators coupled to 35 Hz and 160 Hz horns. This paper documents the acoustic performance of the enhanced noise generation system for a variety of relevant test spectra. Additionally, it demonstrates the capability of the SALT facility to conduct transmission loss and absorption testing in accordance with ASTM and ISO standards, respectively. A few examples of test capabilities are shown and include transmission loss testing of simple unstiffened and built up structures and measurement of the diffuse field absorption coefficient of a fibrous acoustic blanket.

  15. The rock components and structures of Archean greenstone belts: An overview

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.; Byerly, G. R.

    1986-01-01

    Knowledge of the character and evolution of the Earth's early crust is derived from the studies of the rocks and structures in Archean greenstone belts. Ability to resolve the petrologic, sedimentological and structural histories of greenstone belts, however, hinges first on an ability to apply the concepts and procedures of classical stratigraphy. Unfortunately, early Precambrian greenstone terrains present particular problems to stratigraphic analysis. Many current controversies of greenstone belt petrogenesis, sedimentology, tectonics and evolution arise more from an inability to develop a clear stratigraphic picture of the belts than from ambiguities in interpretation. Four particular stratigraphic problems that afflict studies of Archean greenstone belts are considered: determination of facing directions, correlation of lithologic units, identification of primary lithologies and discrimination of stratigraphic versus structural contacts.

  16. Distribution and origin of igneous rocks from the landward slopes of the Mariana Trench: Implications for its structure and evolution

    SciTech Connect

    Bloomer, S.H.

    1983-09-10

    The landward slope of the Mariana Trench is composed largely of igneous rocks. Serpentinites and serpentinized ultramafic rocks occur at nearly all structural levels on the slope from depths of 8000 to 1200 m. Seamountlike features on the trench slope break are the surface expression of serpentinite diapirs. Cumulate and massive gabbros are found; several varieties of volcanic rocks are common including boninites, altered and metamorphosed basalts, andesites, and dacites. The chemical characteristics of the volcanic rocks indicate that nearly all are products of island arc volcanism. Together with the gabbros, these volcanic rocks represent what is probably a late Eocene arc complex. These rocks were probably the first volcanic products to result from the subduction of the Pacific plate beneath the Phillippine Sea plate; their exposure on the trench slope today implies a significant amount of tectonic erosion of the landward slope since Eocene time. Most of this removal of material appears to have occurred during the early stages of subduction. There are isolated occurrences on the landward slope of rock assemblages including alkalic basalts, chert, hyaloclastites, upper Cretaceous siliceous sediments, and shallow water limestones. These assemblages are very similar to rocks dredged from seamounts on the offshore flank of the trench, and their presence on the landward slope suggests that since the cessation of vigorous tectonic erosion, there has been episodic accretion of seamount fragments to the landward slope.

  17. Structure of the ambient temperature alkali metal molten salt AlCl3/LiSCN

    NASA Astrophysics Data System (ADS)

    Lee, Yi-Chia; Price, David L.; Curtiss, Larry A.; Ratner, Mark A.; Shriver, Duward F.

    2001-03-01

    The structure of the ambient temperature alkali metal molten salt system LiSCN/AlCl3 1:1 adduct was investigated by neutron diffraction, which demonstrates that the aluminum atom is surrounded by three chlorine atoms and one nitrogen atom, indicating the existence of the AlCl3NCS- anion, in which the NCS- coordinates to the Al center through nitrogen. Molecular orbital calculations using ab initio methods are also performed to study the optimized structures of the AlCl3NCS- and its isomer, AlCl3SCN-. The results are consistent with the neutron diffraction data and indicate that AlCl3NCS- is the major anionic complex in the 1:1 LiSCN/AlCl3 adduct.

  18. Retrogressive harmonic motion as structural and stylistic characteristic of pop-rock music

    NASA Astrophysics Data System (ADS)

    Carter, Paul S.

    The central issue addressed in this dissertation is that of progressive and retrogressive harmonic motion as it is utilized in the repertoire of pop-rock music. I believe that analysis in these terms may prove to be a valuable tool for the understanding of the structure, style and perception of this music. Throughout my study of this music, various patterns of progressive and retrogressive harmonic motions within a piece reveal a kind of musical character about it, a character on which much of a work's style, organization and extramusical nature often depends. Several influential theorists, especially Jean-Phillipe Rameau, Hugo Riemann, and Arnold Schoenberg, have addressed the issues of functional harmony and the nature of the motion between chords of a tonal harmonic space. After assessing these views, I have found that it is possible to differentiate between two fundamental types of harmonic motions. This difference, one that I believe is instrumental in characterizing pop-rock music, is the basis for the analytical perspective I wish to embrace. After establishing a method of evaluating tonal harmonic root motions in these terms, I wish to examine a corpus of this music in order to discover what a characterization of its harmonic motion may reveal about each piece. Determining this harmonic character may help to establish structural and stylistic traits for that piece, its genre, composer, period, or even its sociological purpose. Conclusions may then be drawn regarding the role these patterns play in defining musical style traits of pop-rock. Partly as a tool for serving the study mentioned above I develop a graphical method of accounting for root motion I name the tonal "Space-Plot"; This apparatus allows the analyst to measure several facets about the harmonic motion of the music, and to see a wide scope of relations in and around a diatonic key.

  19. Structural pattern in the Precambrian rocks of Sonua-Lotapahar region, North Singhbhum, eastern India

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Dhruba; Bhattacharya, Tapas; Chakraborty, Tapan; Dey, Arun Kanti

    1990-06-01

    In the western part of the North Singhbhum fold belt near Lotapahar and Sonua the remobilized basement block of Chakradharpur Gneiss is overlain by a metasedimentary assemblage consisting of quartz arenite, conglomerate, slate-phyllite, greywacke with volcanogenic material, volcaniclastic rocks and chert. The rock assemblage suggests an association of volcanism, turbidite deposition and debris flow in the basin. The grade of metamorphism is very low, the common metamorphic minerals being muscovite, chlorite, biotite and stilpnomelane. Three phases of deformation have affected the rocks. The principal D1 structure is a penetrative planar fabric, parallel to or at low angle to bedding. No D1 major fold is observed and the regional importance of this deformation is uncertain. The D2 deformation has given rise to a number of northerly plunging major folds on E-W axial planes. These have nearly reclined geometry and the L 2lineation is mostly downdip on the S 2surface, though some variation in pitch is observed. The morphology of D2 planar fabric varies from slaty cleavage/schistosity to crenulation cleavage and solution cleavage. D3 deformation is weak and has given rise to puckers and broad warps on schistosity and bedding. The D2 major folds south of Lotapahar are second order folds in the core of the Ongarbira syncline whose easterly closure is exposed east of the mapped area. Photogeological study suggests that the easterly and westerly closing folds together form a large synclinal sheath fold. There is a continuity of structures from north to south and no mylonite belt is present, though there is attenuation and disruption along the fold limbs. Therefore, the Singhbhum shear zone cannot be extended westwards in the present area. There is no evidence that in this area a discontinuity surface separates two orogenic belts of Archaean and Proterozoic age.

  20. Discriminating exhumation models of ultra-high-pressure rocks in the Western Alps by structural record

    NASA Astrophysics Data System (ADS)

    Podladchikov, Yury; Schmalholz, Stefam; Pleuger, Jan; Epard, Jean-Luc

    2014-05-01

    Despite extensive research, the dynamics of tectonic nappes exhibiting high- and ultrahigh-pressure rocks [(U)HP] is still debated. We classify existing models for nappe formation into two types, and refer to them as the thrust and intrusion models. Classical thrust models approximate the orogen as a wedge with a rigid buttress behind and a subducting lithospheric slab beneath. The dominant process of nappe formation is thrusting (brittle and/or ductile) that generates a dominant top-to-the-foreland sense of shear. Thrust models can explain the imbricate nappe stacking and first-order structural observations in the Western Alps. However, in the last decades (U)HP rocks were found in nappes, and it is usually assumed that metamorphic pressure is a good indicator of maximum burial. In intrusion models, (U)HP rocks are subducted to mantle depths (>100 km) and return to crustal depths by buoyancy-driven or tectonically-forced flow. Intrusion models could reproduce the first-order patterns of P-T-t paths of the Western Alps. Nappe formation at such mantle depths cannot be explained by the thrust model; nappe intrusion from large depths into shallower areas seems more appropriate. This argument against thrust models, however, is solely based on the assumption that metamorphic pressure indicates maximum burial (assuming lithostatic pressure). This very assumption is the only argument in favour of the intrusion models. If, however, significant and positive deviations from lithostatic pressure existed during nappe formation, then (U)HP rocks would have been formed at significantly shallower depth, and thrust models could be applicable to the Western Alps reconciling both structural and P-T-t records. Discrimination between the two nappe-forming models can better be achieved by examining the absence of a particular structural record and not by evaluating the existing structural and P-T-t records. A fundamental kinematic (rheology and driving force independent) feature of the

  1. Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)

    NASA Astrophysics Data System (ADS)

    Faure, Michel; Lin, Wei; Schärer, Urs; Shu, Liangshu; Sun, Yan; Arnaud, Nicolas

    2003-10-01

    In the Dabieshan, the available models for exhumation of ultrahigh-pressure (UHP) rocks are poorly constrained by structural data. A comprehensive structural and kinematic map and a general cross-section of the Dabieshan including its foreland fold belt and the Northern Dabieshan Domain (Foziling and Luzenguang groups) are presented here. South Dabieshan consists from bottom to top of stacked allochtons: (1) an amphibolite facies gneissic unit, devoid of UHP rocks, interpreted here as the relative autochton; (2) an UHP allochton; (3) a HP rock unit (Susong group) mostly retrogressed into greenschist facies micaschists; (4) a weakly metamorphosed Proterozoic slate and sandstone unit; and (5) an unmetamorphosed Cambrian to Early Triassic sedimentary sequence unconformably covered by Jurassic sandstone. All these units exhibit a polyphase ductile deformation characterized by (i) a NW-SE lineation with a top-to-the-NW shearing, and (ii) a southward refolding of early ductile fabrics. The Central Dabieshan is a 100-km scale migmatitic dome. Newly discovered eclogite xenoliths in a Cretaceous granitoid dated at 102 Ma by the U-Pb method on titanite demonstrate that migmatization post-dates HP-UHP metamorphism. Ductile faults formed in the subsolidus state coeval to migmatization allow us to characterize the structural pattern of doming. Along the dome margins, migmatite is gneissified under post-solidus conditions and mylonitic-ultramylonitic fabrics commonly develop. The north and west boundaries of the Central Dabieshan metamorphics, i.e. the Xiaotian-Mozitan and Macheng faults, are ductile normal faults formed before Late Jurassic-Early Cretaceous. A Cretaceous reworking is recorded by synkinematic plutons. North of the Xiaotian-Mozitan fault, the North Dabieshan Domain consists of metasediments and orthogneiss (Foziling and Luzenguang groups) metamorphosed under greenschist to amphibolite facies which never experienced UHP metamorphism. A rare N-S-trending lineation

  2. From pre-salt sources to post-salt traps: A specific petroleum system in Congo coastal basin

    SciTech Connect

    Vernet, R.

    1995-08-01

    The Bas Congo basin extends from Gabon to Angola and is a prolific oil province where both pre-salt and post salt sources and reservoirs have been found. In the northern part of the basin referred to as the Congo coastal basin, the proven petroleum system is more specific: mature source rocks are found only in pre-salt series whereas by contrast 99 % proven hydrocarbon reserves am located in post-salt traps. Such a system is controlled by the following factors: Source rocks are mostly organic rich shales deposited in a restricted environment developed in a rift prior to the Atlantic Ocean opening; Migration from pre-salt sources to post-salt traps is finalized by local discontinuities of the regional salt layer acting otherwise as a tight seal; Post-salt reservoirs are either carbonates or sands desposited in the evolutive shelf margin developped during Upper Cretaceous; Geometric traps are linked to salt tectonics (mostly turtle-shaped structures); Regional shaly seals are related to transgressive shales best developped during high rise sea level time interval. Stratigraphically, the age of hydrocarbon fields trends are younger and younger from West to East: lower Albian in Nkossa, Upper Albian and lower Cenomanian in Likouala, Yanga, Sendji, Upper Cenomanian in Tchibouela, Turonian in Tchendo, Turanian and Senonian in Emeraude.

  3. Development of magnetic fabric in sedimentary rocks: insights from early compactional structures

    NASA Astrophysics Data System (ADS)

    García-Lasanta, Cristina; Oliva-Urcia, Belén; Román-Berdiel, Teresa; Casas, Antonio M.; Pérez-Lorente, Félix

    2013-07-01

    The timing of development of the magnetic fabric is a major issue in the application of anisotropy of magnetic susceptibility (AMS) as a strain marker. Analysis of AMS in unconcealed synsedimentary structures can be a sound approximation to this task. In this work, three types of early compactional structures (ECS) were studied by means of AMS, since they can help to understand the timing of development of the magnetic fabric. All three types of ECS are found in fine-grained detrital rocks (to avoid other influences such as palaeocurrents), claystones and marls of the Enciso Group within the Cameros Basin (NE Spain): dinosaur footprints, load structures due to differential compaction and dish-and-flame structures associated with fluid migration related to seismites. In addition, to determine possible influences of lithology on the magnetic fabric, different rock types (siltstones and limestones) were also sampled. In general, the influence of ECS results in scattering of the three magnetic axes, higher at the margins of the structure than at its centre. This fact suggests that ECS occurs during the development of the magnetic fabric, disturbing the incipient magnetic fabric stages, and strongly conditions its later evolution during diagenesis. The later homogeneous compaction process due to sedimentary load and physicochemical processes reorient the susceptibility carriers to some extent (i.e. the magnetic fabric is still under development), but not totally, since AMS still records the previous scattering due to ECS imprint. For the Enciso Group deposits, the magnetic fabric begins to develop at the earliest stages after deposition and it stops when diagenetic processes have finished.

  4. Salt deformation history and postsalt structural trends, offshore southern Gabon, West Africa

    SciTech Connect

    Liro, L.M.; Coen, R.

    1996-12-31

    Salt deformation in offshore southern Gabon is represented by mobilization of an Aptian salt layer in reaction to Tertiary clastic progradation. Seismic mapping of salt bodies and associated faulting has resulted in increased understanding of the types and distribution of these salt bodies, their associated faulting patterns, and some aspects of their origin. Away from the Tertiary depocenter, the growth history of salt swells or pillows can be determined by examining onlapping and draping seismic reflectors. Significant Tertiary clastic progradation into the area mobilized the salt and resulted in a series of linear, deep salt walls and asymmetric, basinward-dipping salt rollers, commonly associated with significant up-to-basin faulting dominates the southern Gabon subbasin. The expansion history of associated sediments suggests that these faults expanded episodically throughout the Tertiary, continuing to present-day bathymetric fault scarps. The bias toward up-to-basin faults, to the apparent exclusion of down-to-basin expansion faults, remains enigmatic.

  5. A Trail of Salts

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph shows the relative abundances of sulfur (in the form of sulfur tri-oxide) and chlorine at three Meridiani Planum sites: soil measured in the small crater where Opportunity landed; the rock dubbed 'McKittrick' in the outcrop lining the inner edge of the crater; and the rock nicknamed 'Guadalupe,' also in the outcrop. The 'McKittrick' data shown here were taken both before and after the rover finished grinding the rock with its rock abrasion tool to expose fresh rock underneath. The 'Guadalupe' data were taken after the rover grounded the rock. After grinding both rocks, the sulfur abundance rose to high levels, nearly five times higher than that of the soil. This very high sulfur concentration reflects the heavy presence of sulfate salts (approximately 30 percent by weight) in the rocks. Chloride and bromide salts are also indicated. Such high levels of salts strongly suggest the rocks contain evaporite deposits, which form when water evaporates or ice sublimes into the atmosphere.

  6. Impact-generated endolithic habitat within crystalline rocks of the Haughton impact structure, Devon Island, Canada.

    PubMed

    Pontefract, Alexandra; Osinski, Gordon R; Cockell, Charles S; Moore, Casey A; Moores, John E; Southam, Gordon

    2014-06-01

    The colonization of rocks by endolithic communities is an advantageous trait, especially in environments such as hot or cold deserts, where large temperature ranges, low water availability, and high-intensity ultraviolet radiation pose a significant challenge to survival and growth. On Mars, similar conditions (albeit more extreme) prevail. In these environments, meteorite impact structures could provide refuge for endolithic organisms. Though initially detrimental to biology, an impact event into a rocky body can favorably change the availability and habitability of a substrate for endolithic organisms, which are then able to (re)colonize microfractures and pore spaces created during the impact. Here, we show how shocked gneisses from the Haughton impact structure, Devon Island, Canada, offer significant refuge for endolithic communities. A total of 28 gneiss samples representing a range of shock states were analyzed, collected from in situ, stable field locations. For each sample, the top centimeter of rock was examined with confocal scanning laser microscopy, scanning electron microscopy, and bright-field microscopy to investigate the relationship of biomass with shock level, which was found to correlate generally with increased shock state and particularly with increased porosity. We found that gneisses, which experienced pressures between 35 and 60 GPa, provide the most ideal habitat for endolithic organisms. PMID:24926727

  7. Extensional salt tectonics in the partially inverted Cotiella post-rift basin (south-central Pyrenees): structure and evolution

    NASA Astrophysics Data System (ADS)

    López-Mir, Berta; Muñoz, Josep Anton; García-Senz, Jesús

    2015-03-01

    The Cotiella Massif in the south-central Pyrenees hosts upper Cretaceous gravity-driven extensional faults which were developed in the Bay of Biscay-Pyrenean paleorift margin of the Atlantic Ocean. They accommodate up to 6 km of post-rift carbonates above relict upper Triassic salt. Subsequent Pyrenean contractional deformation preserved the main extensional features, but most of the upper Triassic salt was expulsed and then dissolved, leaving little indications of the original salt volume. Nonetheless, several distinctive salt-related features are still recognizable both at outcrop and at basin scale, providing an exposed analogue for salt-floored extensional basins developed on passive margins. Based on field research, we re-interpret the tectonic evolution of the area and suggest that passive diapirs were coeval with gravity-driven extension during the development of the Cotiella basin. The given interpretations are supported with detailed geological maps, original structural data, cross sections and outcrop photographs. The discovery of previously unknown post-rift salt structures in the Cotiella Massif is an extra element to consider in the paleogeographic reconstructions of the upper Cretaceous passive margin of the Bay of Biscay-Pyrenean realm and consequently helps in our understanding of the evolution of current Atlantic-type margins.

  8. Rock Valley Source Physics Experiment Preparation: Earthquake Relocation and Attenuation Structure Characterization

    NASA Astrophysics Data System (ADS)

    Pyle, M. L.; Walter, W. R.; Myers, S.; Pasyanos, M. E.; Smith, K. D.

    2012-12-01

    ensure that we have the best possible locations for the 1993 Rock Valley earthquake sequence, and current ongoing microseismicity in the region, we are using the new Bayesloc multiple-event location algorithm (Myers et al., 2007; 2009) to improve hypocentral locations. Bayesloc formulates the location problem as a hierarchy of the traveltime model with travel time corrections, an arrival time model including picking errors, and a prior model for each parameter. Since these events occur on the NNSS, we have the ability to test and fine-tune regional relocation parameters using known locations of previous nuclear tests. In addition, in order to ensure that any SPE explosion is large enough to be recorded at the same regional stations as the original earthquake sequence over a reasonable frequency range, we are performing a seismic amplitude tomography. The tomography uses NNSS earthquake seismicity to determine local and near regional P and S-wave attenuation structure, allowing us to better predict signal-to-noise values for a variety of possible SPE scenarios. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-571335

  9. Liquid Nickel Salts: Synthesis, Crystal Structure Determination, and Electrochemical Synthesis of Nickel Nanoparticles.

    PubMed

    Sniekers, Jeroen; Verguts, Ken; Brooks, Neil R; Schaltin, Stijn; Phan, Thanh Hai; Trung Huynh, Thi Mien; Van Meervelt, Luc; De Feyter, Steven; Seo, Jin Won; Fransaer, Jan; Binnemans, Koen

    2016-01-18

    New nickel-containing ionic liquids were synthesized, characterized and their electrochemistry was investigated. In addition, a mechanism for the electrochemical synthesis of nanoparticles from these compounds is proposed. In these so-called liquid metal salts, the nickel(II) cation is octahedrally coordinated by six N-alkylimidazole ligands. The different counter anions that were used are bis(trifluoromethanesulfonyl)imide (Tf2 N(-) ), trifluoromethanesulfonate (OTf(-) ) and methanesulfonate (OMs(-) ). Several different N-alkylimidazoles were considered, with the alkyl sidechain ranging in length from methyl to dodecyl. The newly synthesized liquid metal salts were characterized by CHN analysis, FTIR, DSC, TGA and viscosity measurements. An odd-even effect was observed for the melting temperatures and viscosities of the ionic liquids, with the complexes with an even number of carbon atoms in the alkyl chain of the imidazole having a higher melting temperature and a lower viscosity than the complexes with an odd number of carbons. The crystal structures of several of the nickel(II) complexes that are not liquid at room temperature were determined. The electrochemistry of the compounds with the lowest viscosities was investigated. The nickel(II) cation could be reduced but surprisingly no nickel deposits were obtained on the electrode. Instead, nickel nanoparticles were formed at 100 % selectivity, as confirmed by TEM. The magnetic properties of these nanoparticles were investigated by SQUID measurements. PMID:26643274

  10. Control of molten salt corrosion of fusion structural materials by metallic beryllium

    NASA Astrophysics Data System (ADS)

    Calderoni, P.; Sharpe, P.; Nishimura, H.; Terai, T.

    2009-04-01

    A series of tests have been performed between 2001 and 2006 at the Safety and Tritium Applied Research facility of the Idaho National Laboratory to demonstrate chemical compatibility between the molten salt flibe (2LiF + BeF 2 in moles) and fusion structural materials once suitable fluoride potential control methods are established. The tests adopted metallic beryllium contact as main fluoride potential control, and the results have been published in recent years. A further step was to expose two specimens of low activation ferritic/martensitic steel 9Cr-2W to static corrosion tests that include an active corrosion agent (hydrofluoric gas) in controlled conditions at 530 °C, and the results of the tests are presented in this paper. The results confirmed the expected correlation of the HF recovery with the concentration of metallic impurities dissolved in the salt because of specimen corrosion. The metals concentration dropped to levels close to the detectable limit when the beryllium rod was inserted and increased once the content of excess beryllium in the system had been consumed by HF reduction and specimen corrosion progressed. Metallographic analysis of the samples after 500 h exposure in reactive conditions showed evidence of the formation of unstable chromium oxide layers on the specimen's surface.

  11. Crustal structure and basin architecture, De Soto Canyon Salt basin, northeastern Gulf of Mexico

    SciTech Connect

    MacRae, G. . Dept. of Oceanography); Watkins, J.S. . Dept. of Geophysics)

    1992-01-01

    Evolution of sedimentary basins in the Gulf of Mexico can be explained by extensional processes associated with a rifted, passively subsiding continental margin. The De Soto Canyon Salt Basin in the northeastern Gulf of Mexico contains a thick sequence of Mesozoic and Cenozoic sediments which have accumulated almost continuously since the Middle Jurassic, in a relatively stable, slowly subsiding tectonic environment. Simplified isostatic principles based on a lithosphere buoyancy model are used to quantify total tectonic subsidence, crust thickness, crustal extension and crust type. Regional gravity anomaly trends reflect the interpreted crustal configuration. Multifold seismic reflection data and well data are integrated with computed isostatic relations to establish the basic architecture of the basin. An average estimated crustal thickness of 25 km and Beta-values between 1.4 and 1.8 suggest the sedimentary succession is underlain by moderately stretched and attenuated continental crust. Linear east-west and NNW-SSE trends in Beta-value contours indicate major crustal discontinuities in the region of the Mississippi-Alabama-Florida (MAFLA) shelf and beneath the west Florida shelf, respectively. The geometry of dipping sub-salt reflectors defines a major graben extending east-west in the central part of the basin. These structural trends are thought to be in response to Late Triassic-Early Jurassic rifting. The present-day configuration of the basin was established by the Middle Jurassic.

  12. Evolution of salt structures, East Texas Diapir Province, Part 1: Sedimentary record of Halokinesis

    SciTech Connect

    Seni, S.J.; Jackson, M.P.A.

    1983-08-01

    Post-Aptian (post-112Ma) strata in the East Texas basin were strongly influenced by halokinesis and therefore record the evolution of associated salt structures. Domeinduced changes in patterns of sandstone distribution, depositional facies, and reef growth indicate that thickness variations in strata surrounding domes were caused by syndepositional processes rather than by tectonic distortion. Salt domes in the East Texas basin exhibit three stages of growth: pillow, diapir, and post-diapir, each of which affected surrounding strata differently. Pillow growth caused broad uplift of strata over the crest of the pillows; the resulting topographic swell influenced depositional trends and was susceptible to erosion. Fluvial channel systems bypassed pillow crests and stacked vertically in primary peripheral sinks on the updip flanks of the pillows. Diapir growth was characterized by expanded sections of shelf and deltaic strata in secondary peripheral sinks around the diapirs. Lower Cretaceous reefs on topographic saddles between secondary peripheral sinks now host major oil production at Fairway field. Post-diapir crestal uplifts and peripheral subsidence affected smaller areas than did equivalent processes during pillow or diapir stages. Documented facies variations over and around domes at different stages of growth enable prediction of subtle facies-controlled hydrocarbon traps. Facies-controlled traps are likely to be the only undiscovered ones remaining in mature petroliferous basins such as the East Texas basin.

  13. Evolution of salt structures, East Texas diapir province, part 1: sedimentary record of halokinesis

    SciTech Connect

    Seni, S.J.; Jackson M.P.A.

    1983-08-01

    Post-Aptian (post-112 Ma) strata in the East Texas basin were strongly influenced by halokinesis and therefore record the evolution of associated salt structures. Dome-induced changes in patterns of sandstone distribution, depositional facies, and reef growth indicate that thickness variations in strata surrounding domes were caused by syndepositional processes rather than by tectonic distortion. Salt domes in the East Texas basin exhibit three stages of growth: pillow, diapir, and post-diapir, each of which affected surrounding strata differently. Pillow growth caused broad uplift of strata over the crest of the pillows; the resulting topographic swell influenced depositional trends and was susceptible to erosion. Fluvial channel systems bypassed pillow crests and stacked vertically in primary peripheral sinks on the updip flanks of the pillows. Diapir growth was characterized by expanded sections of shelf and deltaic strata in secondary peripheral sinks around the diapirs. Lower Cretaceous reefs on topographic saddles between secondary peripheral sinks now host major oil production at Fairway field. Post-diapir crestal uplifts and peripheral subsidence affected smaller areas than did equivalent processes during pillow or diapir stages. Documented facies variations over and around domes at different stages of growth enable prediction of subtle facies-controlled hydrocarbon traps. Facies-controlled traps are likely to be the only undiscovered ones remaining in mature petroliferous basins such as the East Texas basin.

  14. Sliding and Rocking of Unanchored Components and Structures: Chapter 7.6 ASCE 4 Revision 2

    SciTech Connect

    S. R. Jensen

    2011-04-01

    Chapter 7.6 of ASCE 4-Rev 2, Seismic Analysis of Safety-Related Nuclear Structures: Standard and Commentary, provides updated guidance for analysis of rocking and sliding of unanchored structures and components subjected to seismic load. This guidance includes provisions both for simplified approximate energy-based approaches, and for detailed probabilistic time history analysis using nonlinear methods. Factors to be applied to the analytical results are also provided with the intent of ensuring achievement of the 80% non-exceedence probability target of the standard. The present paper surveys the published literature supporting these provisions. The results of available testing and analysis are compared to results produced by both simplified and probabilistic approaches. In addition, adequacy of the standard's provisions for analysis methods and factors is assessed. A comparison is made between the achieved level of conservatism and the standard's non-exceedence probability target.

  15. Anisotropic rock physics models for interpreting pore structures in carbonate reservoirs

    NASA Astrophysics Data System (ADS)

    Li, Sheng-Jie; Shao, Yu; Chen, Xu-Qiang

    2016-03-01

    We developed an anisotropic effective theoretical model for modeling the elastic behavior of anisotropic carbonate reservoirs by combining the anisotropic self-consistent approximation and differential effective medium models. By analyzing the measured data from carbonate samples in the TL area, a carbonate pore-structure model for estimating the elastic parameters of carbonate rocks is proposed, which is a prerequisite in the analysis of carbonate reservoirs. A workflow for determining elastic properties of carbonate reservoirs is established in terms of the anisotropic effective theoretical model and the pore-structure model. We performed numerical experiments and compared the theoretical prediction and measured data. The result of the comparison suggests that the proposed anisotropic effective theoretical model can account for the relation between velocity and porosity in carbonate reservoirs. The model forms the basis for developing new tools for predicting and evaluating the properties of carbonate reservoirs.

  16. Petrology and structure of Pwemain to Jurassic rocks near Yreka, Klamath Mountains, California

    NASA Astrophysics Data System (ADS)

    Mortimer, N.

    Rocks of the western Paleozoic and Triasic Belt (TrPz belt) of Irwin (1966) in the north eastern Klamath Mountains of California can be subdivided into the same lithotectonic units (terranes) recognized in the southern and central Klamath Mountains. In descending structural order, these are the Fort Jones, North Fork, Salmon River, Havfork and Marble Mountains terranes of Blake and others (1982). Stratigraphic and petrologic regions are consistent with the North Fork, Salmon River and eastern Hayford terranes evolved in close proximity to each other since their origin in Permian time. Faunal and sedimentological evidence suggest that the North Fork terrane was probably at least hundreds of kilometers distant from North America in Permian time, but was close to the continent by early Jurassic time. The structural and metamorphic history of the terranes is consistent with assembly of the TrPz belt in a single, evolving middle and late Jurassic arc/subduction system.

  17. Self-assembly of ordered wurtzite/rock salt heterostructures—A new view on phase separation in Mg{sub x}Zn{sub 1−x}O

    SciTech Connect

    Gries, K. I.; Vogel, S.; Straubinger, R.; Beyer, A.; Chernikov, A.; Chatterjee, S.; Volz, K.; Wassner, T. A.; Bruckbauer, J.; Häusler, I.; Laumer, B.; Kracht, M.; Heiliger, C.; Eickhoff, M.; Janek, J.

    2015-07-28

    The self-assembled formation of ordered, vertically stacked rocksalt/wurtzite Mg{sub x}Zn{sub 1−x}O heterostructures by planar phase separation is shown. These heterostructures form quasi “natural” two-dimensional hetero-interfaces between the different phases upon annealing of MgO-oversaturated wurtzite Mg{sub x}Zn{sub 1−x}O layers grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. The optical absorption spectra show a red shift simultaneous with the appearance of a cubic phase upon annealing at temperatures between 900 °C and 1000 °C. Transmission electron microscopy reveals that these effects are caused by phase separation leading to the formation of a vertically ordered rock salt/wurtzite heterostructures. To explain these observations, we suggest a phase separation epitaxy model that considers this process being initiated by the formation of a cubic (Mg,Zn)Al{sub 2}O{sub 4} spinel layer at the interface to the sapphire substrate, acting as a planar seed for the epitaxial precipitation of rock salt Mg{sub x}Zn{sub 1−x}O. The equilibrium fraction x of magnesium in the resulting wurtzite (rock salt) layers is approximately 0.15 (0.85), independent of the MgO content of the as-grown layer and determined by the annealing temperature. This model is confirmed by photoluminescence analysis of the resulting layer systems after different annealing temperatures. In addition, we show that the thermal annealing process results in a significant reduction in the density of edge- and screw-type dislocations, providing the possibility to fabricate high quality templates for quasi-homoepitaxial growth.

  18. Pore-Scale Modeling of Pore Structure Effects on P-Wave Scattering Attenuation in Dry Rocks

    PubMed Central

    Li, Tianyang; Qiu, Hao; Wang, Feifei

    2015-01-01

    Underground rocks usually have complex pore system with a variety of pore types and a wide range of pore size. The effects of pore structure on elastic wave attenuation cannot be neglected. We investigated the pore structure effects on P-wave scattering attenuation in dry rocks by pore-scale modeling based on the wave theory and the similarity principle. Our modeling results indicate that pore size, pore shape (such as aspect ratio), and pore density are important factors influencing P-wave scattering attenuation in porous rocks, and can explain the variation of scattering attenuation at the same porosity. From the perspective of scattering attenuation, porous rocks can safely suit to the long wavelength assumption when the ratio of wavelength to pore size is larger than 15. Under the long wavelength condition, the scattering attenuation coefficient increases as a power function as the pore density increases, and it increases exponentially with the increase in aspect ratio. For a certain porosity, rocks with smaller aspect ratio and/or larger pore size have stronger scattering attenuation. When the pore aspect ratio is larger than 0.5, the variation of scattering attenuation at the same porosity is dominantly caused by pore size and almost independent of the pore aspect ratio. These results lay a foundation for pore structure inversion from elastic wave responses in porous rocks. PMID:25961729

  19. Pore-scale modeling of pore structure effects on P-wave scattering attenuation in dry rocks.

    PubMed

    Wang, Zizhen; Wang, Ruihe; Li, Tianyang; Qiu, Hao; Wang, Feifei

    2015-01-01

    Underground rocks usually have complex pore system with a variety of pore types and a wide range of pore size. The effects of pore structure on elastic wave attenuation cannot be neglected. We investigated the pore structure effects on P-wave scattering attenuation in dry rocks by pore-scale modeling based on the wave theory and the similarity principle. Our modeling results indicate that pore size, pore shape (such as aspect ratio), and pore density are important factors influencing P-wave scattering attenuation in porous rocks, and can explain the variation of scattering attenuation at the same porosity. From the perspective of scattering attenuation, porous rocks can safely suit to the long wavelength assumption when the ratio of wavelength to pore size is larger than 15. Under the long wavelength condition, the scattering attenuation coefficient increases as a power function as the pore density increases, and it increases exponentially with the increase in aspect ratio. For a certain porosity, rocks with smaller aspect ratio and/or larger pore size have stronger scattering attenuation. When the pore aspect ratio is larger than 0.5, the variation of scattering attenuation at the same porosity is dominantly caused by pore size and almost independent of the pore aspect ratio. These results lay a foundation for pore structure inversion from elastic wave responses in porous rocks. PMID:25961729

  20. Dramatically Stabilizing Multiprotein Complex Structure in the Absence of Bulk Water using Tuned Hofmeister Salts

    PubMed Central

    Han, Linjie; Hyung, Suk-Joon; Ruotolo, Brandon T.

    2012-01-01

    The role that water plays in the salt-based stabilization of proteins is central to our understanding of protein biophysics. Ion hydration and the ability of ions to alter water surface tension are typically invoked, along with direct ion-protein binding, to describe Hofmeister stabilization phenomena observed for proteins experimentally, but the relative influence of these forces has been extraordinarily difficult to measure directly. Recently, we have used gas-phase measurements of proteins and large multiprotein complexes, using a combination of innovative ion mobility (IM) and mass spectrometry (MS) techniques, to assess the ability of bound cations and anions to stabilize protein ions in the absence of the solvation forces described above. Our previous work has studied a broad set of 12 anions bound to a range of proteins and protein complexes, and while primarily motivated by the analytical challenges surrounding the gas-phase measurement of solution-phase relevant protein structures, our work has also lead to a detailed physical mechanism of anion-protein complex stabilization in the absence of bulk solvent. Our more-recent work has screened a similarly-broad set of cations for their ability to stabilize gas-phase protein structure, and we have discovered surprising differences between the operative mechanisms for cations and anions in gas-phase protein stabilization. In both cases, cations and anions affect protein stabilization in the absence of solvent in a manner that is generally reversed relative to their ability to stabilize the same proteins in solution. In addition, our evidence suggests that the relative solution-phase binding affinity of the anions and cations studied here is preserved in our gas-phase measurements, allowing us to study the influence of such interactions in detail. In this report, we collect and summarize such gas-phase measurements to distill a generalized picture of salt-based protein stabilization in the absence of bulk water

  1. Comparison of wetland structural characteristics between created and natural salt marshes in southwest Louisiana, USA

    USGS Publications Warehouse

    Edwards, K.R.; Proffitt, C.E.

    2003-01-01

    The use of dredge material is a well-known technique for creating or restoring salt marshes that is expected to become more common along the Gulf of Mexico coast in the future. However, the effectiveness of this restoration method is still questioned. Wetland structural characteristics were compared between four created and three natural salt marshes in southwest Louisiana, USA. The created marshes, formed by the pumping of dredge material into formerly open water areas, represent a chronosequence, ranging in age from 3 to 19 years. Vegetation and soil structural factors were compared to determine whether the created marshes become more similar over time to the natural salt marshes. Vegetation surveys were conducted in 1997, 2000, and 2002 using the line-intercept technique. Site elevations were measured in 2000. Organic matter (OM) was measured in 1996 and 2002, while bulk density and soil particle-size distribution were determined in 2002 only. The natural marshes were dominated by Spartina alterniflora, as were the oldest created marshes; these marshes had the lowest mean site elevations ( 35 cm NGVD) and became dominated by high marsh (S. patens, Distichlis spicata) and shrub (Baccharis halimifolia, Iva frutescens) species. The higher elevation marsh seems to be following a different plant successional trajectory than the other marshes, indicating a relationship between marsh elevation and species composition. The soils in both the created and natural marshes contain high levels of clays (30-65 %), with sand comprising < 1 % of the soil distribution. OM was significantly greater and bulk density significantly lower in two of the natural marshes when compared to the created marshes. The oldest created marsh had significantly greater OM than the younger created marshes, but it may still take several decades before equivalency is reached with the natural marshes. Vegetation structural characteristics in the created marshes take only a few years to become similar

  2. Structure and catalytic properties of magnesia-supported copper salts of molybdovanadophosphoric acid.

    PubMed

    Zhou, Guangdong; Yang, Xiaomei; Liu, Jie; Zhen, Kaiji; Wang, Haishui; Cheng, Tiexin

    2006-05-25

    The structure and stability of magnesia-supported copper salts of molybdovanadophosphoric acid (Cu(2)PMo(11)VO(40)) were characterized by different techniques. The catalyst was prepared in ethanol by impregnation because this solvent does not hurt texture of the water-sensitive MgO and Cu(2)PMo(11)VO(40). The Keggin-type structure compound may be degraded partially to form oligomerized polyoxometalate when supported on MgO. However, the oligomers can rebuild as the Keggin structure again after thermal treatment in air or during the reaction. Meanwhile, the V atoms migrate out of the Keggin structure to form a lacunary structure, as observed by Fourier transform IR spectroscopy. Moreover, the presence of Cu(2+) as a countercation showed an affirmative influence on the migration of V atoms, and the active sites derived from the lacunary species generated after release of V from the Keggin anion. The electron paramagnetic resonance data imply that V(5+) autoreduces to V(4+) in the fresh catalyst, and during the catalytic reaction a large number of V(4+) ions are produced, which enhance the formation of O(2-) vacancies around the metal atoms. These oxygen vacancies may also improve the reoxidation function of the catalyst. This behavior is correlated to higher catalytic properties of this catalyst. The oxidative dehydrogenation of hexanol to hexanal was studied over this catalyst. After reaction at 553.2 K for 50 h, catalytic properties did not decrease and exhibited higher selectivity (>96.0%) toward hexanal. PMID:16706435

  3. Quartz Microstructures in Rocks From the Rochechouart Impact Structure, France - High Stress Deformation and Subsequent Annealing

    NASA Astrophysics Data System (ADS)

    Trepmann, C. A.

    2006-12-01

    Quartz microstructures in impact breccias and target rocks from the Rochechouart impact structure, as well as rocks not affected by shock, outside the structure, are compared. Suevites and impact breccias contain clasts of shocked quartz that show planar fractures (PFs), planar deformation features (PDFs) and mosaicism, as revealed by transmission electron microscopy (TEM). PDFs comprise fluid inclusions and dislocations aligned in narrow strings mostly parallel to the π and ω rhombohedra of quartz. The spacing between PDFs is typically <0.5 μm. Multiple PDF sets intersect each other. Dislocation walls separate cells in the interspace between PDFs. Mosaicism is characterized by tiny cells (<0.5 μm in diameter) that are markedly misoriented, as indicated by streaky diffraction spots. Planar features occur, along which the cells are aligned, probably representing remnants of PDFs. These characteristics imply high shock pressures on the order of 20 GPa during shock. The microstructure apparent in the TEM indicates post-shock recovery and recrystallisation at probably quasi-static conditions. Shocked quartz in autochthonous gneisses at ~5 km NE of the assumed centre of the structure show few PDFs parallel to the ω rhombohedra and/or basal PDFs, which represent mechanical Brazil twins. In general, PDF density is lower in shocked quartz from authochthonous target rocks compared to shocked quartz from impact breccias. These characteristics imply that the target rocks are affected by shock pressures on the order of 8 GPa. In most gneisses no cataclastic deformation is recorded by the microfabric. In autochthonous recrystallized vein quartz, however, cataclastic zones show a shear offset of up to 0.5 mm and comprise small cataclasites with an average diameter of 7±4 μm. Quartz containing basal PDFs is restricted to these cataclastic zones. Rhombohedral PDFs do not occur. These characteristics imply low shock pressures and a high shock-induced differential stress. In

  4. Structural evolution of lamprophyric dikes in Lailai, northeastern coast of Taiwan, deduced from mesoscopic structures in dikes and country rocks

    NASA Astrophysics Data System (ADS)

    You, Cian-Siang; Huang, Wen-Jeng; Lo, Wei; Wang, Tzu-Bin; Chen, Chien-Chih

    2015-04-01

    Lamprophyric dikes are standing in right-stepping en echelon up to 2.3 meters high within the Oligocene Tatungshan formation on the Lai-Lai wave-cut platform in the northeastern coast of Taiwan. The marine platform composed mainly of argillite is the extension of Hsuehshan range, which has the tallest peak of 3,886 m high in Taiwan. The dikes formed at depth in the late Miocene of 9±1.1 Ma ago are exposed on the marine platform nowadays due to the exhumation and Penglai orogeny resulting from the collision of Eurasian plate and Philippine Sea plate, which began in Pleistocene of 5-6 Ma ago. In consequence, folds, faults, joints and other structures are associated with them. In this study, the distribution of the dikes and fractures were mapped by conducting accurate surveys with a total station theodolite and orthorectifying aerial images taken by an unmanned aerial vehicle in different elevations. Electrical resistivity exploration was performed to decipher the arrangement of the dikes underground and the characteristics of the faults. The associated mesoscopic structures were delineated by mapping at a scale of 1: 40 in the field. We infer that the dikes was formed at depth of approximately 2.4 kilometers according to the thickness of overlaying sedimentary rocks formed from late Oligocene to late Miocene. Thus, it excludes the possibility that fractures existed before the lamprophyric magma intruded into the country rocks. Our observations help restore the original status of the current 19 dike segments. We conclude that the lamprophyric magma forcedly and vertically intruded into the Oligocene rocks and the direction change of maximum principle stress at depth of 2.4 kilometers resulted in three or more right-stepping en-echelon dikes.

  5. Salt-influenced structures in the mesozoic-tertiary cover of the southern North Sea, U.K.

    SciTech Connect

    Coward, M.; Stewart, S.

    1996-12-31

    A structural model encompassing the southern North Sea Basin west of the Central Graben has been developed that combines gravity gliding of the postsalt cover with basement tectonics. The basin differs from many salt basins in that it forms a closed system. Section construction and balancing through the cover of the North Sea need to take into account thin-skinned and thick-skinned extensions and contractions. The North Sea salt formed in Permian time in two large oval basins separated by the Mid North Sea High. The shape of these basins reflects variable patterns of thermal subsidence. Subsequent salt tectonics was governed by local graben structures and by regional uplift and subsidence. Rifting initiated during the Triassic and allowed reactive and locally passive diapirs to develop in the post-salt cover. In the southern North Sea, the Dowsing graben system in the cover is offset from the Dowsing fault zone below the salt. This offset in extensional structures probably relates to the salt thickness and to the position of the surface hinge line that controlled the onset of gravity gliding in the postsalt section. Gravity gliding of the cover into the Triassic-Jurassic Sole Pit trough and away from zones of rift flank uplift was associated with Late Jurassic-Early Cretaceous extension in the Central North Sea; gliding caused asymmetric compressional pillows to develop downslope. Gravity spreading of the cover during the Late Cretaceous-early Tertiary was associated with tilting during thermal subsidence of the southern North Sea Basin, enhanced by pulses of tectonic inversion in the southern North Sea basement. The resultant glide tectonics formed new small grabens upslope and compressional pillows downslope. Where the compressional pillows were eroded sufficiently or faulted later, the salt broke through the thinned cover to produce new active and then passive diapirs, which drained the pillows to produce new rim synclines.

  6. Structural evidence for solvent-stabilisation by aspartic acid as a mechanism for halophilic protein stability in high salt concentrations.

    PubMed

    Lenton, Samuel; Walsh, Danielle L; Rhys, Natasha H; Soper, Alan K; Dougan, Lorna

    2016-07-21

    Halophilic organisms have adapted to survive in high salt environments, where mesophilic organisms would perish. One of the biggest challenges faced by halophilic proteins is the ability to maintain both the structure and function at molar concentrations of salt. A distinct adaptation of halophilic proteins, compared to mesophilic homologues, is the abundance of aspartic acid on the protein surface. Mutagenesis and crystallographic studies of halophilic proteins suggest an important role for solvent interactions with the surface aspartic acid residues. This interaction, between the regions of the acidic protein surface and the solvent, is thought to maintain a hydration layer around the protein at molar salt concentrations thereby allowing halophilic proteins to retain their functional state. Here we present neutron diffraction data of the monomeric zwitterionic form of aspartic acid solutions at physiological pH in 0.25 M and 2.5 M concentration of potassium chloride, to mimic mesophilic and halophilic-like environmental conditions. We have used isotopic substitution in combination with empirical potential structure refinement to extract atomic-scale information from the data. Our study provides structural insights that support the hypothesis that carboxyl groups on acidic residues bind water more tightly under high salt conditions, in support of the residue-ion interaction model of halophilic protein stabilisation. Furthermore our data show that in the presence of high salt the self-association between the zwitterionic form of aspartic acid molecules is reduced, suggesting a possible mechanism through which protein aggregation is prevented. PMID:27327567

  7. Spin Frustration in an Organic Radical Ion Salt Based on a Kagome-Coupled Chain Structure.

    PubMed

    Postulka, Lars; Winter, Stephen M; Mihailov, Adam G; Mailman, Aaron; Assoud, Abdeljalil; Robertson, Craig M; Wolf, Bernd; Lang, Michael; Oakley, Richard T

    2016-08-31

    Electro-oxidation of the quinoidal bisdithiazole BT in dichloroethane in the presence of [Bu4N][GaBr4] affords the 1:1 radical ion salt [BT][GaBr4], crystals of which belong to the trigonal space group P3. The packing pattern of the radical cations provides a rare example of an organic kagome basket structure, with S = 1/2 radical ion chains located at the triangular corners of a trihexagonal lattice. Magnetic measurements over a wide temperature range from 30 mK to 300 K suggest strongly frustrated AFM interactions on the scale of J/kb ∼ 30 K, but reveal no anomalies that would be associated with magnetic order. These observations are discussed in terms of the symmetry allowed magnetic interactions within and between the frustrated layers. PMID:27537064

  8. Structure characterization of the non-crystalline complexes of copper salts with native cyclodextrins.

    PubMed

    Velasco, Manuel I; Krapacher, Claudio R; de Rossi, Rita H; Rossi, Laura I

    2016-06-28

    The characterization of non-crystalline complexes is particularly difficult when techniques like X-ray diffraction or NMR cannot be used. We propose a simple procedure to characterize the physicochemical properties of amorphous new coordination compounds between cyclodextrins (CD) and Cu(2+) salts, by means of the integration of the information provided by several techniques including elemental analysis, flame atomic absorption, TGA, UV-Vis diffuse reflectance, colorimetry, FT-IR and EPR. On the basis of these procedures, we suggest geometrical and structural approximations resulting in an octahedral or distorted octahedral geometry with diverse positions for the metallic centre. According to the EPR spectrum, only one of the complexes may have rhombic symmetry. We also analyzed enthalpy-entropy compensation and the isokinetic effect. In addition, general trends in thermal stability, spectroscopic properties and inclusion in the cavity were analysed. This complete characterization methodology becomes essential for their future application as catalysts. PMID:27272478

  9. Monoclinic tridymite in clast-rich impact melt rock from the Chesapeake Bay impact structure

    USGS Publications Warehouse

    Jackson, J.C.; Horton, J.W., Jr.; Chou, I.-Ming; Belkin, H.E.

    2011-01-01

    X-ray diffraction and Raman spectroscopy confirm a rare terrestrial occurrence of monoclinic tridymite in clast-rich impact melt rock from the Eyreville B drill core in the Chesapeake Bay impact structure. The monoclinic tridymite occurs with quartz paramorphs after tridymite and K-feldspar in a microcrystalline groundmass of devitrified glass and Fe-rich smectite. Electron-microprobe analyses revealed that the tridymite and quartz paramorphs after tridymite contain different amounts of chemical impurities. Inspection by SEM showed that the tridymite crystal surfaces are smooth, whereas the quartz paramorphs contain irregular tabular voids. These voids may represent microporosity formed by volume decrease in the presence of fluid during transformation from tridymite to quartz, or skeletal growth in the original tridymite. Cristobalite locally rims spherulites within the same drill core interval. The occurrences of tridymite and cristobalite appear to be restricted to the thickest clast-rich impact melt body in the core at 1402.02-1407.49 m depth. Their formation and preservation in an alkali-rich, high-silica melt rock suggest initially high temperatures followed by rapid cooling.

  10. Structures of biogenic origin from Early Precambrian rocks of Euro-Asia.

    PubMed

    Lopuchin, A S

    1975-01-01

    Spheroidal microfossils mainly 20 to 100 mug in diameter and exhibiting granular surface textures have been recovered from Early Precambrian rocks by applying a new method of water separation in combination with thin chemical preparation. In contrast to the Acritarcha, these microfossils are characterized by a relatively low specific weight (close to one) and considerable fragility due to impregnation by mineral matter. They occur in Archean sediments of Hindustan, in rocks of the Baltic and Aldan Shields with ages of 3.0 to 3.5 billion (10-9) years, and in Proterozoic deposits in many regions of Euro-Asia. They commonly occur in great number in Precambrian sediments of West Africa, Australia and North America. These forms are here regarded as Menneria Lopuchin and are considered to be blue-green algae. Menneria resembles alga-like forms reported by Engel, Nagy and their co-workers from the Onverwacht Series and microfossils reported by Schopf and Barghoorn from the Fig Tree Series, both of the Swaziland System of southern Africa. In addition to spheroidal microfossils, ribbon-like and filiform microstructures are here reported from Archean deposits. The biogenic structures here described from the Early Precambrian of Euro-Asia are considered to have been photosynthetic and planktonic. Their progressive evolution, intensive production of organic matter, and biogeochemical role in concentration of rare elements is discussed. PMID:807898

  11. Strain localization in ductile rocks: A comparison of natural and simulated pinch-and-swell structures

    NASA Astrophysics Data System (ADS)

    Peters, Max; Berger, Alfons; Herwegh, Marco; Regenauer-Lieb, Klaus

    2016-06-01

    We study pinch-and-swell structures in order to uncover the onset of strain localization and the change of deformation mechanisms in layered ductile rocks. To this end, boudinaged monomineralic veins embedded in an ultramylonitic matrix are analyzed quantitatively. The swells are built up by relatively undeformed original calcite grains, showing twinning and minor subgrain rotation recrystallization (SGR). Combined with progressive formation of high-angle misorientations between grains, indicative of SGR, severe grain size reduction defines the transition to the pinches. Accordingly, dynamically recrystallized grains have a strong crystallographic preferred orientation (CPO). Toward the necks, further grain size reduction, increasingly random misorientations, nucleation of new grains, and a loss of the CPO occur. We postulate that this microstructure marks the transition from dislocation to diffusion creep induced by strain localization. We confirm that the development of boudins is insensitive to original grain sizes and single-crystal orientations. In order to test these microstructural interpretations, a self-consistent numerical grain size evolution is implemented, based on thermo-mechanical principles, end-member flow laws and microphysical processes. Applying constant velocity and isothermal boundary conditions to a 3-layer finite element pure shear box, pinch-and-swell structures emerge out of the homogeneous layer through grain size softening at a critical state. Viscosity weakening due to elevated strain rates and dissipated heat from grain size reduction promotes strain rate weakening until a critical grain size is reached. At this point, a switch from dislocation to diffusion creep occurs. This state locks in at local steady states and is microstructurally expressed in pinches and swells, respectively. Thus, boudinage is identified as an energy attractor, identifying the high-energy steady state of an extending layered structure. We conclude from the

  12. Rock magnetic and paleomagnetic study of the Keurusselkä impact structure, central Finland

    NASA Astrophysics Data System (ADS)

    Raiskila, Selen; Salminen, Johanna; Elbra, Tiiu; Pesonen, Lauri J.

    2011-11-01

    There are 31 proven impact structures in Fennoscandia—one of the most densely crater-populated areas of the Earth. The recently discovered Keurusselkä impact structure (62°08' N, 24°37' E) is located within the Central Finland Granitoid Complex, which formed 1890-1860 Ma ago during the Svecofennian orogeny. It is a deeply eroded complex crater that yields in situ shatter cones with evidence of shock metamorphism, e.g., planar deformation features in quartz. New petrophysical and rock magnetic results of shocked and unshocked target rocks of various lithologies combined with paleomagnetic studies are presented. The suggested central uplift with shatter cones is characterized by increased magnetization and susceptibility. The presence of magnetite and pyrrhotite was observed as carriers for the remanent magnetization. Four different remanent magnetization directions were isolated: (1) a characteristic Svecofennian target rock component A with a mean direction of D = 334.8°, I = 45.6°, α95 = 14.9° yielding a pole (Plat = 51.1°, Plon = 241.9°, A95 = 15.1°), (2) component B, D = 42.4°, I = 64.1°, α95 = 8.4° yielding a pole (Plat = 61.0°, Plon = 129.1°, A95 = 10.6°), (3) component C (D = 159.5°, I = 65.4°, α95 = 10.7°) yielding a pole (Plat = 21.0°, Plon = 39.3°, A95 = 15.6°), and (4) component E (D = 275.5°, I = 62.0°, α95 = 14.4°) yielding a pole (Plat = 39.7°, Plon = 314.3°, A95 = 19.7°). Components C and E are considered much younger, possibly Neoproterozoic overprints, compared with the components A and B. The pole of component B corresponds with the 1120 Ma pole of Salla diabase dyke and is in agreement with the 40Ar/39Ar age of 1140 Ma from a pseudotachylitic breccia vein in a central part of the structure. Therefore, component B could be related to the impact, and thus represent the impact age.

  13. Structure and anisotropy of the crust in the Cyclades, Greece, using receiver functions constrained by in situ rock textural data

    NASA Astrophysics Data System (ADS)

    Cossette, Élise; Audet, Pascal; Schneider, David; Grasemann, Bernhard

    2016-04-01

    Seismic anisotropy data are often used to resolve rock textures and deformation in the crust based on compilations of rock properties that may not be representative of the local geology. In this paper, we use teleseismic receiver functions jointly with in situ rock property data to constrain the seismic structure and anisotropy of the crust in the Cyclades, Greece, located in the back-arc region of the Hellenic subduction zone. The receiver function data indicate that the Moho is relatively flat at 25 km depth toward the south and deepens to 33 km in the north, consistent with previous studies, and reveal an intracrustal discontinuity at depths varying from 3 to 11 km, mostly observed in the south central Aegean. Harmonic decomposition of the receiver functions further indicates the presence of both shallow and deep crustal anisotropy related to crustal structures. We model synthetic receiver functions based on constraints from in situ rock properties that we measured using the electron backscatter diffraction technique. Our results indicate that the shallow upper crustal layer is characterized by metapelites with ~5% anisotropy, underlain by a 20 km thick and possibly anisotropic layer of high-pressure rocks comprising blueschist and eclogite and/or restitic crust resulting from magmatism. This study demonstrates the importance of rock textural data in the interpretation of seismic velocity profiles.

  14. Paleomagnetic and rock magnetic study of the Mistastin Lake impact structure (Labrador, Canada): Implications for geomagnetic perturbation and shock effects

    NASA Astrophysics Data System (ADS)

    Hervé, Gwenaël; Gilder, Stuart A.; Marion, Cassandra L.; Osinski, Gordon R.; Pohl, Jean; Petersen, Nikolai; Sylvester, Paul J.

    2015-05-01

    We carried out an integrated rock magnetic and paleomagnetic study of the ∼36 Ma Mistastin Lake (Labrador, Canada) meteorite impact structure in order to investigate whether energy from the collision influenced the geodynamo and to assess the effects of shock on the magnetic properties of the target basement rocks. Stepwise demagnetization of 114 specimens isolates a well-defined magnetization component throughout the crater whose overall mean deviates slightly from the expected direction for North America at the time of impact. Paleointensity results from seven samples meeting stringent selection criteria show no significant difference with a global compilation from 40 to 30 Ma. The combined results, including those from a ∼80 m-thick profile of an impact melt unit (Discovery Hill), lend no support that the impact caused an aberration of the geodynamo within a few centuries of a bolide collision that created the ∼28 km-diameter crater. Both titanium-rich and titanium-poor titanomagnetite carry the magnetic remanence in the impact melt rocks; their relative proportions, compositions and domain states are cooling rate dependent. Magnetic hysteresis parameters of the magnetite-bearing anorthositic basement rocks reveal systematic changes as a function of distance from the crater's center with an increasing prevalence of single domain-like grains toward the center. Changes with radial distance are also found in the character of the Verwey transition in magnetite. Basement rocks were thermally overprinted when lying less than a meter from the impact melt rocks; Mesoproterozoic basement rocks more than a meter below the impact melt rocks hold similar magnetization directions to those expected from a 1500 Ma result for Laurentia. No evidence exists that shock heating of the basement rocks exceeded 200 °C at distances of 6-7 km from the crater's center.

  15. An engineering rock classification to evaluate seismic rock-fall susceptibility and its application to the Wasatch front

    SciTech Connect

    Harp, E.L.; Noble, M.A.

    1993-09-01

    The authors examine the characteristics of rock slopes that make them susceptible to failures caused by earthquakes. They discuss these characteristics, namely the fracture and joint properties that define the structural behavior of a rock mass at the surface, and then present an empirical engineering classification or ranking system that rates the relative seismic susceptibility of rock masses. They next apply the engineering classification in a case study of seismically-triggered rock falls in the Mammoth Lakes area. The engineering classification is correlated with the concentration of seismically-triggered rock falls, and the resulting statistical model can be used to predict the probability of a rock fall for a given magnitude earthquake. Finally, they apply the classification and probability analysis to similar slopes in the Wasatch Range near Salt Lake City and evaluate the relative susceptibility of slopes in this area to seismically-induced failure.

  16. The structure and IR signatures of the arginine-glutamate salt bridge. Insights from the classical MD simulations

    NASA Astrophysics Data System (ADS)

    Vener, M. V.; Odinokov, A. V.; Wehmeyer, C.; Sebastiani, D.

    2015-06-01

    Salt bridges and ionic interactions play an important role in protein stability, protein-protein interactions, and protein folding. Here, we provide the classical MD simulations of the structure and IR signatures of the arginine (Arg)-glutamate (Glu) salt bridge. The Arg-Glu model is based on the infinite polyalanine antiparallel two-stranded β-sheet structure. The 1 μs NPT simulations show that it preferably exists as a salt bridge (a contact ion pair). Bidentate (the end-on and side-on structures) and monodentate (the backside structure) configurations are localized [Donald et al., Proteins 79, 898-915 (2011)]. These structures are stabilized by the short +N-H⋯O- bonds. Their relative stability depends on a force field used in the MD simulations. The side-on structure is the most stable in terms of the OPLS-AA force field. If AMBER ff99SB-ILDN is used, the backside structure is the most stable. Compared with experimental data, simulations using the OPLS all-atom (OPLS-AA) force field describe the stability of the salt bridge structures quite realistically. It decreases in the following order: side-on > end-on > backside. The most stable side-on structure lives several nanoseconds. The less stable backside structure exists a few tenth of a nanosecond. Several short-living species (solvent shared, completely separately solvated ionic groups ion pairs, etc.) are also localized. Their lifetime is a few tens of picoseconds or less. Conformational flexibility of amino acids forming the salt bridge is investigated. The spectral signature of the Arg-Glu salt bridge is the IR-intensive band around 2200 cm-1. It is caused by the asymmetric stretching vibrations of the +N-H⋯O- fragment. Result of the present paper suggests that infrared spectroscopy in the 2000-2800 frequency region may be a rapid and quantitative method for the study of salt bridges in peptides and ionic interactions between proteins. This region is usually not considered in spectroscopic

  17. The structure and IR signatures of the arginine-glutamate salt bridge. Insights from the classical MD simulations

    SciTech Connect

    Vener, M. V.; Odinokov, A. V.; Wehmeyer, C.; Sebastiani, D.

    2015-06-07

    Salt bridges and ionic interactions play an important role in protein stability, protein-protein interactions, and protein folding. Here, we provide the classical MD simulations of the structure and IR signatures of the arginine (Arg)–glutamate (Glu) salt bridge. The Arg-Glu model is based on the infinite polyalanine antiparallel two-stranded β-sheet structure. The 1 μs NPT simulations show that it preferably exists as a salt bridge (a contact ion pair). Bidentate (the end-on and side-on structures) and monodentate (the backside structure) configurations are localized [Donald et al., Proteins 79, 898–915 (2011)]. These structures are stabilized by the short {sup +}N–H⋯O{sup −} bonds. Their relative stability depends on a force field used in the MD simulations. The side-on structure is the most stable in terms of the OPLS-AA force field. If AMBER ff99SB-ILDN is used, the backside structure is the most stable. Compared with experimental data, simulations using the OPLS all-atom (OPLS-AA) force field describe the stability of the salt bridge structures quite realistically. It decreases in the following order: side-on > end-on > backside. The most stable side-on structure lives several nanoseconds. The less stable backside structure exists a few tenth of a nanosecond. Several short-living species (solvent shared, completely separately solvated ionic groups ion pairs, etc.) are also localized. Their lifetime is a few tens of picoseconds or less. Conformational flexibility of amino acids forming the salt bridge is investigated. The spectral signature of the Arg-Glu salt bridge is the IR-intensive band around 2200 cm{sup −1}. It is caused by the asymmetric stretching vibrations of the {sup +}N–H⋯O{sup −} fragment. Result of the present paper suggests that infrared spectroscopy in the 2000–2800 frequency region may be a rapid and quantitative method for the study of salt bridges in peptides and ionic interactions between proteins. This region is

  18. Internal structure of fault zones in geothermal reservoirs: Examples from palaeogeothermal fields and potential host rocks

    NASA Astrophysics Data System (ADS)

    Leonie Philipp, Sonja; Reyer, Dorothea; Meier, Silke; Bauer, Johanna F.; Afşar, Filiz

    2014-05-01

    Fault zones commonly have great effects on fluid transport in geothermal reservoirs. During fault slip all the pores and small fractures that meet with the slip plane become interconnected so that the inner part of the fault, the fault core, consisting of breccia or gouge, may suddenly develop a very high permeability. This is evidenced, for example by networks of mineral veins in deeply eroded fault zones in palaeogeothermal fields. Inactive faults, however, may have low permeabilities and even act as flow barriers. In natural and man-made geothermal reservoirs, the orientation of fault zones in relation to the current stress field and their internal structure needs be known as accurately as possible. One reason is that the activity of the fault zone depends on its angle to the principal stress directions. Another reason is that the outer part of a fault zone, the damage zone, comprises numerous fractures of various sizes. Here we present field examples of faults, and associated joints and mineral veins, in palaeogeothermal fields, and potential host rocks for man-made geothermal reservoirs, respectively. We studied several localities of different stratigraphies, lithologies and tectonic settings: (1) 58 fault zones in 22 outcrops from Upper Carboniferous to Upper Cretaceous in the Northwest German Basin (siliciclastic, carbonate and volcanic rocks); (2) 16 fault zones in 9 outcrops in Lower Permian to Middle Triassic (mainly sandstone, limestone and granite) in the Upper Rhine Graben; and (3) 74 fault zones in two coastal sections of Upper Triassic and Lower Jurassic age (mudstones and limestone-marl alternations) in the Bristol Channel Basin, UK. (1) and (2) are outcrop analogues of geothermal reservoir horizons, (3) represent palaeogeothermal fields with mineral veins. The field studies in the Northwest German Basin (1) show pronounced differences between normal-fault zones in carbonate and clastic rocks. In carbonate rocks clear damage zones occur that are

  19. Geophysical modeling of the structural relationships between the Precambrian Reading Prong rocks and the Paleozoic sedimentary sequence, Easton quadrangle, PA

    SciTech Connect

    Thomas, D.M.; Malinconico, L.L. Jr. . Dept. of Geology)

    1993-03-01

    This project involves the geophysical modeling of the structural relationships between the Precambrian Reading Prong rocks and the Paleozoic sedimentary cover rocks near Easton, Pennsylvania. The Precambrian rocks have generally been assumed to have been emplaced on the Paleozoic sequence along a shallow thrust fault. However, at present time the attitude of the faults bordering the Precambrian terranes are all very steeply dipping. This was explained by the subsequent folding of the whole sequence during later orogenic activity. The objective of this work is to determine the attitude and depth of the fault contact between the Precambrian crystalline rocks and the Paleozoic sedimentary rocks. A series of traverses (each separated by approximately one mile) were established perpendicular to the strike of the Precambrian rocks. Along each traverse both gravity and magnetic readings were taken at 0.2 kilometer intervals. The data were reduced and presented as profiles and contour maps. Both the magnetic and gravity data show positive anomalies that correlate spatially with the location of the Precambrian rocks. The gravity data have a long wavelength regional trend increasing to the north with a shorter wavelength anomaly of 2 milligals which coincides with the Precambrian rocks. The magnetic data have a single positive anomaly of almost 1,000 gammas which also coincides with the Precambrian terrane. These data will now be used to develop two dimensional density and susceptibility models of the area. From these models, the thickness of each formation and the structural relationships between them, as well as the attitude and depth of the fault contact will be determined.

  20. Seismic wave velocity of rocks in the Oman ophiolite: constraints for petrological structure of oceanic crust

    NASA Astrophysics Data System (ADS)

    Saito, S.; Ishikawa, M.; Shibata, S.; Akizuki, R.; Arima, M.; Tatsumi, Y.; Arai, S.

    2010-12-01

    Evaluation of rock velocities and comparison with velocity profiles defined by seismic refraction experiments are a crucial approach for understanding the petrological structure of the crust. In this study, we calculated the seismic wave velocities of various types of rocks from the Oman ophiolite in order to constrain a petrological structure of the oceanic crust. Christensen & Smewing (1981, JGR) have reported experimental elastic velocities of rocks from the Oman ophiolite under oceanic crust-mantle conditions (6-430 MPa). However, in their relatively low-pressure experiments, internal pore-spaces might affect the velocity and resulted in lower values than the intrinsic velocity of sample. In this study we calculated the velocities of samples based on their modal proportions and chemical compositions of mineral constituents. Our calculated velocities represent the ‘pore-space-free’ intrinsic velocities of the sample. We calculated seismic velocities of rocks from the Oman ophiolite including pillow lavas, dolerites, plagiogranites, gabbros and peridotites at high-pressure-temperature conditions with an Excel macro (Hacker & Avers 2004, G-cubed). The minerals used for calculations for pillow lavas, dolerites and plagiogranites were Qtz, Pl, Prh, Pmp, Chl, Ep, Act, Hbl, Cpx and Mag. Pl, Hbl, Cpx, Opx and Ol were used for the calculations for gabbros and peridotites. Assuming thermal gradient of 20° C/km and pressure gradient of 25 MPa/km, the velocities were calculated in the ranges from the atmospheric pressure (0° C) to 200 MPa (160° C). The calculation yielded P-wave velocities (Vp) of 6.5-6.7 km/s for the pillow lavas, 6.6-6.8 km/s for the dolerites, 6.1-6.3 km/s for the plagiogranites, 6.9-7.5 km/s for the gabbros and 8.1-8.2 km/s for the peridotites. On the other hand, experimental results reported by Christensen & Smewing (1981, JGR) were 4.5-5.9 km/s for the pillow lavas, 5.5-6.3 km/s for the dolerites, 6.1-6.3 km/s for the plagiogranites, 6

  1. Allosteric mechanism of haemoglobin: rupture of salt-bridges raises the oxygen affinity of the T-structure.

    PubMed

    Bettati, S; Mozzarelli, A; Perutz, M F

    1998-08-28

    The T-structure of human haemoglobin is linked by salt-bridges between its four subunits, formed by the C-terminal arginine residues of the alpha-subunits and the C-terminal histidine residues of the beta-subunits. In the R-structure, these salt-bridges are absent. The oxygen affinity of the T-structure is lower than that of the R-structure by the equivalent of 3.5 kcal/mol haem. This difference has been attributed to the constraints imposed upon the T-structure by the salt-bridges, which were thought to hinder the changes in tertiary structure needed for firm oxygen binding. We have subjected this postulate to a rigorous test by measuring the oxygen equilibria of T-state crystals of an abnormal human haemoglobin in which the C-terminal histidine residues of the beta-chains are replaced by leucine residues. This replacement removes the salt-bridges from the histidine imidazole groups to the neighbouring aspartate residues. The crystals have an oxygen affinity about three times greater than that of crystals of normal haemoglobin. Hill's coefficient is close to unity. The oxygen affinity is unaffected by pH, chloride or the allosteric effector bezafibrate. Equilibrium curves determined by single crystal microspectrophometry using light polarised parallel and normal to the crystallographic a-axis show no significant difference between the oxygen affinities of alpha and beta-haems. Our results show that rupture of salt-bridges raises the oxygen affinity of the T-structure even when this is clamped firmly by the crystal lattice. PMID:9710531

  2. Experimental studies the evolution of stress-strain state in structured rock specimens under uniaxial loading

    NASA Astrophysics Data System (ADS)

    Oparin, Viktor; Tsoy, Pavel; Usoltseva, Olga; Semenov, Vladimir

    2014-05-01

    The aim of this study was to analyze distribution and development of stress-stress state in structured rock specimens subject to uniaxial loading to failure. Specific attention was paid to possible oscillating motion of structural elements of the rock specimens under constraints (pre-set stresses at the boundaries of the specimens) and the kinetic energy fractals. The detailed studies into the micro-level stress-strain state distribution and propagation over acting faces of rock specimens subject to uniaxial loading until failure, using automated digital speckle photography analyzer ALMEC-tv, have shown that: • under uniaxial stiff loading of prismatic sandstone, marble and sylvinite specimens on the Instron-8802 servohydraulic testing machine at the mobile grip displacement rate 0.02-0.2 mm/min, at a certain level of stressing, low-frequency micro-deformation processes originate in the specimens due to slow (quasi-static) force; • the amplitude of that deformation-wave processes greatly depends on the micro-loading stage: — at the elastic deformation stage, under the specimen stress lower than half ultimate strength of the specimen, there are no oscillations of microstrains; —at the nonlinearly elastic deformation stage, under stress varied from 0.5 to 1 ultimate strength of the specimens, the amplitudes of microstrains grow, including the descending stage 3; the oscillation frequency f=0.5-4 Hz; —at the residual strength stage, the amplitudes of the microstrains drop abruptly (3-5 times) as against stages 2 and 3; • in the elements of the scanned specimen surface in the region with the incipient crack, the microstrain rate amplitudes are a few times higher than in the undamged surface region of the same specimen. Sometimes, deformation rate greatly grows with increase in the load. The authors have used the energy scanning function of the deformation-wave processes in processing experimental speckle-photography data on the surface of the test specimen

  3. Elastic properties and secondary structure formation of single-stranded DNA at monovalent and divalent salt conditions

    PubMed Central

    Bosco, Alessandro; Camunas-Soler, Joan; Ritort, Felix

    2014-01-01

    Single-stranded DNA (ssDNA) plays a major role in several biological processes. It is therefore of fundamental interest to understand how the elastic response and the formation of secondary structures are modulated by the interplay between base pairing and electrostatic interactions. Here we measure force-extension curves (FECs) of ssDNA molecules in optical tweezers set up over two orders of magnitude of monovalent and divalent salt conditions, and obtain its elastic parameters by fitting the FECs to semiflexible models of polymers. For both monovalent and divalent salts, we find that the electrostatic contribution to the persistence length is proportional to the Debye screening length, varying as the inverse of the square root of cation concentration. The intrinsic persistence length is equal to 0.7 nm for both types of salts, and the effectivity of divalent cations in screening electrostatic interactions appears to be 100-fold as compared with monovalent salt, in line with what has been recently reported for single-stranded RNA. Finally, we propose an analysis of the FECs using a model that accounts for the effective thickness of the filament at low salt condition and a simple phenomenological description that quantifies the formation of non-specific secondary structure at low forces. PMID:24225314

  4. Crystal structure of a lithium salt of a glucosyl derivative of lithocholic acid.

    PubMed

    Gubitosi, Marta; Meijide, Francisco; D'Annibale, Andrea; Vázquez Tato, José; Jover, Aida; Galantini, Luciano; Travaglini, Leana; di Gregorio, Maria Chiara; Pavel, Nicolae V

    2016-09-01

    The crystal structure of a Li(+) salt of a glucosyl derivative of lithocholic acid (lithium 3α-(α-d-glucopyranosyl)-5β-cholan-24-oate) has been solved. The crystal belongs to the orthorhombic system, P212121 spatial group, and includes acetone and water in the structure with a 1:1:2 stoichiometry. Monolayers, having a hydrophobic interior and hydrophilic edges, are recognized in the crystal structure. Li(+) is coordinated to three hydroxyl groups of three different glucose residues, with two of them belonging to the same monolayer. A fourth molecule, located in this monolayer, is involved in the coordination of the cation through the carboxylate ion by an electrostatic interaction, thus completing a distorted tetrahedron. All Li(+)-oxygen distances values are very close to the sum of the ionic radius of Li(+) and van der Waals radius of oxygen. Each steroid molecule is linked to other five steroid molecules through hydrogen bonds. Water and acetone are also involved in the hydrogen bond network. A hierarchical organization can be recognized in the crystal, the helical assembly along 21 screw axes being left-handed. PMID:27394960

  5. Formation of dome and basin structures: Results from scaled experiments using non-linear rock analogues

    NASA Astrophysics Data System (ADS)

    Zulauf, J.; Zulauf, G.; Zanella, F.

    2016-09-01

    Dome and basin folds are structures with circular or slightly elongate outcrop patterns, which can form during single- and polyphase deformation in various tectonic settings. We used power-law viscous rock analogues to simulate single-phase dome-and-basin folding of rocks undergoing dislocation creep. The viscosity ratio between a single competent layer and incompetent matrix was 5, and the stress exponent of both materials was 7. The samples underwent layer-parallel shortening under bulk pure constriction. Increasing initial layer thickness resulted in a decrease in the number of domes and basins and an increase in amplitude, A, arc-length, L, wavelength, λ, and layer thickness, Hf. Samples deformed incrementally show progressive development of domes and basins until a strain of eY=Z = -30% is attained. During the dome-and-basin formation the layer thickened permanently, while A, L, and λ increased. A dominant wavelength was not attained. The normalized amplitude (A/λ) increased almost linearly reaching a maximum of 0.12 at eY=Z = -30%. During the last increment of shortening (eY=Z = -30 to -40%) the domes and basins did not further grow, but were overprinted by a second generation of non-cylindrical folds. Most of the geometrical parameters of the previously formed domes and basins behaved stable or decreased during this phase. The normalized arc-length (L/Hf) of domes and basins is significantly higher than that of 2D cylindrical folds. For this reason, the normalized arc length can probably be used to identify domes and basins in the field, even if these structures are not fully exposed in 3D.

  6. Subsurface structure and hydrocarbon occurrence, cretaceous rocks of Maxie and Pistol Ridge Fields, Southeastern Mississippi

    SciTech Connect

    Luo, S.; Meylan, M.A. )

    1993-09-01

    Maxie and Pistol Ridge fields are located along the southern boundary of the Mississippi Salt basin and northern edge of the Wiggins arch in Forrest and Pearl River counties, Mississippi. Together, the fields have produced about 12 million bbl of oil and 600 mcf of gas to date, primarily from the lower Tuscaloosa Formation. Production ranges from the Hosston to the Wilcox. A field study using 281 electric logs was done to determine controls on hydrocarbon distribution, emphasizing the Dantzler and Upper Cretaceous section. Almost all hydrocarbon traps at the fields are related to the Maxie-Pistol Ridge fault, a northward-dipping normal fault extending about 18 mi in an east-west direction. Maximum throw along the fault is about 300 ft (at the Dantzler and Lower Tuscaloosa Formation horizons), and it dies out upward into the lower part of the Tertiary. Several smaller antithetic and synthetic faults occur parallel to subparallel to the main fault. On the downthrown side of the fault, hydrocarbons occur in two rollover structures designated here as the Maxie anticline and the Pistol Ridge faulted anticline. The former, slightly higher, has trapped mostly lower Tuscaloosa gas, while the latter, structurally lower, contain dominantly oil, spread stratigraphically from the Paluxy to the Eutaw/upper Tuscaloosa. Upthrown structural traps are low-relief simple closures of fault-closed noses on what are designated as the East and West Wiggins anticlines. Hosston and Rodessa pay in the latter is referred to as West Pistol Ridge field.

  7. Structural analysis of the Cordillera Blanca detachment: Geometry, kinematics and fault rocks

    NASA Astrophysics Data System (ADS)

    Shaw, C. A.; Jessup, M. J.; Hughes, C. A.; Newell, D. L.

    2015-12-01

    The Cordillera Banca Detachment (CBD) in the north-central Peruvian Andes is recognized as a rare example of active extension parallel to the direction of shortening within a convergent orogenic setting. Despite longstanding interest in the geodynamic significance of the CBD relatively little work has been done to characterize the basic geometry, kinematics and evolution of the detachment or the petrology and distribution of brittle and ductile tectonites within the fault zone. This contribution presents preliminary results of a basic structural analysis of the CBD based on field observations, laboratory results, and GIS analysis. Basic structural observations of fault geometry and kinematics are needed to constrain the regional geodynamic role of the CBD. The NNW topographic trace of the CBD is defined by faceted ridges up to 2000 m in height. The lower slopes of the facets are locally cut by steep fault scarps that offset quaternary glacial moraines, debris fans and colluvium. The shear zone comprises both brittle and ductile tectonites including mylonite series rocks, pseudotachylyte, and breccia - often highly silicified. Highly polished mirrored surfaces are observed locally. Deformation mechanisms show a consistent progression from plastic in structurally lower positions to brittle in structurally higher positions. Evidence for overprinting deformation mechanisms is preserved in many samples. The shear zone ranges up to about 200 m thick. The average orientation of mylonitic foliation and fault slip surfaces (strike/dip = 140/30) and lineations/slickenlines (plunge-trend = 35-235) is quite consistent along the ~200 km detachment, but some systematic variation along strike may be related to concave fault segments or corrugations. Slip indicators are nearly down-dip with a minor left-lateral or right-lateral component in some locations. Offsets in marker horizons constrain total offset between about 4500 m near the central section of the fault to near zero

  8. Examination of Below-Ground Structure and Soil Respiration Rates of Stable and Deteriorating Salt Marshes in Jamaica Bay (NY)

    EPA Science Inventory

    CAT scan imaging is currently being used to examine below-ground peat and root structure in cores collected from salt marshes of Jamaica Bay, part of the Gateway National Recreation Area (NY). CAT scans or Computer-Aided Tomography scans use X-ray equipment to produce multiple i...

  9. Shape of pinch and swell structures as a viscosity indicator: Application to lower crustal polyphase rocks

    NASA Astrophysics Data System (ADS)

    Gardner, Robyn L.; Piazolo, Sandra; Daczko, Nathan R.

    2016-07-01

    Pinch and swell structures occur where a more competent layer in a weaker matrix is subjected to layer-parallel extension. In this contribution, we use numerical models to explore the use of pinch and swell structure shape symmetry and asymmetry as a determinant of relative viscosity between layers. Maximum asymmetry is attained when the matrix viscosity on one side is subtly weaker than the competent layer, while the other side is significantly weaker. Our numerical results are directly applied to asymmetrically developed pinch and swell structures in exposed lower continental crust. Here, shape geometries observed in a shear zone comprised of plagioclase-dominated, garnet-dominated and mixed amphibole-plagioclase-dominated bands, reveals that the plagioclase-dominated band is the most competent band and is marginally stronger (2×) and significantly stronger (10-40×) than the fine grained garnet-dominated and mixed amphibole-plagioclase-dominated band, respectively. Based on the experimentally determined viscosity of a plagioclase-dominated material and quantitative microstructural analysis, the viscosity range of the natural rock bands is 2.8 × 1015 to 1.1 × 1017 Pa s. Consequently, the assumption that the experimentally-derived plagioclase flow law is an appropriate proxy for the middle to lower continental crust may lead to a viscosity over-estimation by up to forty times.

  10. Isolation, structure identification and SAR studies on thiosugar sulfonium salts, neosalaprinol and neoponkoranol, as potent α-glucosidase inhibitors.

    PubMed

    Xie, Weijia; Tanabe, Genzoh; Akaki, Junji; Morikawa, Toshio; Ninomiya, Kiyofumi; Minematsu, Toshie; Yoshikawa, Masayuki; Wu, Xiaoming; Muraoka, Osamu

    2011-03-15

    Two hitherto missing members of sulfonium salts family in Salacia genus plants as a new class of α-glucosidase inhibitors, neoponkoranol (7) and neosalaprinol (8), were isolated from the water extracts, and their structures were unambiguously identified. For further SAR studies on this series of sulfonium salts, several epimers of 7 and 8 were synthesized, and their inhibitory activities against rat small intestinal α-glucosidases were evaluated. Among them, 3'-epimer of 7 was found most potent in this class of molecules, and revealed as potent as currently used antidiabetics, voglibose and acarbose. PMID:21345683

  11. Resource Assessment of the In-Place and Potentially Recoverable Deep Natural Gas Resource of the Onshore Interior Salt Basins, North Central and Northeastern Gulf of Mexico

    SciTech Connect

    Ernest A. Mancini; Donald A. Goddard

    2005-04-15

    The principal research effort for the first six months of Year 2 of the project has been petroleum system characterization. Understanding the burial and thermal maturation histories of the strata in the onshore interior salt basins of the North Central and Northeastern Gulf of Mexico areas is important in petroleum system characterization. The underburden and overburden rocks in these basins and subbasins are a product of their rift-related geohistory. Petroleum source rock analysis and thermal maturation and hydrocarbon expulsion modeling indicate that an effective regional petroleum source rock in the onshore interior salt basins, the North Louisiana Salt Basin, Mississippi Interior Salt Basin, Manila Subbasin and Conecuh Subbasin, was the Upper Jurassic Smackover lime mudstone. The Upper Cretaceous Tuscaloosa shale was an effective local petroleum source rock in the Mississippi Interior Salt Basin and a possible local source bed in the North Louisiana Salt Basin. Hydrocarbon generation and expulsion was initiated in the Early Cretaceous and continued into the Tertiary in the North Louisiana Salt Basin and the Mississippi Interior Salt Basin. Hydrocarbon generation and expulsion was initiated in the Late Cretaceous and continued into the Tertiary in the Manila Subbasin and Conecuh Subbasin. Reservoir rocks include Jurassic, Cretaceous and Tertiary siliciclastic and carbonate strata. Seal rocks include Jurassic, Cretaceous and Tertiary anhydrite and shale beds. Petroleum traps include structural and combination traps.

  12. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    SciTech Connect

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M.; Lynden-Bell, Ruth M.

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF{sub 6}]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO{sub 3}]{sup −} and [PF{sub 6}]{sup −} anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca{sup 2

  13. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    NASA Astrophysics Data System (ADS)

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M.; Gallego, Luis J.; Varela, Luis M.

    2015-09-01

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3]- and [PF6]- anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca2+ cations. No qualitative difference with

  14. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids.

    PubMed

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M; Gallego, Luis J; Varela, Luis M

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3](-) and [PF6](-) anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca(2+) cations. No qualitative

  15. Principles of rock deformation

    SciTech Connect

    Nicolas, A.

    1987-01-01

    This text focuses on the recent achievements in the analysis of rock deformation. It gives an analytical presentation of the essential structures in terms of kinetic and dynamic interpretation. The physical properties underlying the interpretation of rock structures are exposed in simple terms. Emphasized in the book are: the role of fluids in rock fracturing; the kinematic analysis of magnetic flow structures; the application of crystalline plasticity to the kinematic and dynamic analysis of the large deformation imprinted in many metamorphic rocks.

  16. The salt-sensitive structure and zinc inhibition of Borrelia burgdorferi protease BbHtrA.

    PubMed

    Russell, Theresa M; Tang, Xiaoling; Goldstein, Jason M; Bagarozzi, Dennis; Johnson, Barbara J B

    2016-02-01

    HtrA serine proteases are highly conserved and essential ATP-independent proteases with chaperone activity. Bacteria express a variable number of HtrA homologues that contribute to the virulence and pathogenicity of bacterial pathogens. Lyme disease spirochetes possess a single HtrA protease homologue, Borrelia burgdorferi HtrA (BbHtrA). Previous studies established that, like the human orthologue HtrA1, BbHtrA is proteolytically active against numerous extracellular proteins in vitro. In this study, we utilized size exclusion chromatography and blue native polyacrylamide gel electrophoresis (BN-PAGE) to demonstrate BbHtrA oligomeric structures that were substrate independent and salt sensitive. Examination of the influence of transition metals on the activity of BbHtrA revealed that this protease is inhibited by Zn(2+) > Cu(2+) > Mn(2+). Extending this analysis to two other HtrA proteases, E. coli DegP and HtrA1, revealed that all three HtrA proteases were reversibly inhibited by ZnCl2 at all micro molar concentrations examined. Commercial inhibitors for HtrA proteases are not available and physiologic HtrA inhibitors are unknown. Our observation of conserved zinc inhibition of HtrA proteases will facilitate structural and functional studies of additional members of this important class of proteases. PMID:26480895

  17. Correlation between salt-induced change in water structure and lipid structure of multi-lamellar vesicles observed by terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Choi, Da-Hye; Son, Heyjin; Jeong, Jin-Young; Park, Gun-Sik

    2016-08-01

    Salt-induced change in the structure of water molecules inside multi-lamellar vesicles is experimentally studied with terahertz time-domain spectroscopy. The complex dielectric constant of 1, 2-ditetradecanoyl-sn-glycero-3-phosphocholine model membranes dispersed in NaCl solution with different salt concentrations are measured. Structure of water molecules in the solution is characterized from the measured dielectric constant using Debye relaxation model. Combined with small-angle X-ray scattering observation, it is found that salt-induced change of water structure, especially fast water fraction, show strong correlation with the increase in nanometer-scale multi-lamellar repeat space. This suggests that water could be critical in nanometer-scale membrane-membrane communications.

  18. Stable isotope study of the Archaean rocks of the Vredefort impact structure, central Kaapvaal Craton, South Africa

    NASA Astrophysics Data System (ADS)

    Fagereng, Åke; Harris, Chris; La Grange, Mandy; Stevens, Gary

    2008-01-01

    The Vredefort dome in the Kaapvaal Craton was formed as a result of the impact of a large meteorite at 2.02 Ga. The central core of Archaean granitic basement rocks is surrounded by a collar of uplifted and overturned strata of the Witwatersrand Supergroup, exposing a substantial depth section of the Archaean crust. Orthogneisses of the core show little variation in whole-rock δ 18O value, with the majority being between 8 and 10‰, with a mean of 9.2‰ ( n = 35). Quartz and feldspar have per mil differences that are consistent with O-isotope equilibrium at high temperatures, suggesting minimal interaction with fluids during subsequent cooling. These data refute previous suggestions that the Outer Granite Gneiss (OGG) and Inlandsee Leucogranofels (ILG) of the core represent middle and lower crust, respectively. Granulite-facies greenstone remnants from the ILG have δ 18O values that are on average 1.5‰ higher than the ILG host rocks and are unlikely, therefore, to represent the residuum from the partial melting event that formed the host rock. Witwatersrand Supergroup sedimentary rocks of the collar, which were metamorphosed at greenschist-to amphibolite-facies conditions, generally have lower δ 18O values than the core rocks with a mean value for metapelites of 7.7‰ ( n = 45). Overall, through an ˜20 km thick section of crust, there is a general increase in whole-rock δ 18O value with increasing depth. This is the reverse of what is normal in the crust, largely because the collar rocks have δ 18O values that are unusually low in comparison with metamorphosed sedimentary rocks worldwide. The collar rocks have δD values ranging from -35 to -115‰ (average -62‰, n = 29), which are consistent with interaction with water of meteoric origin, having a δD of about -25 to -45‰. We suggest that fluid movement through the collar rocks was enhanced by impact-induced secondary permeability in the dome structure.

  19. The global range of subduction zone thermal structures from exhumed blueschists and eclogites: Rocks are hotter than models

    NASA Astrophysics Data System (ADS)

    Penniston-Dorland, Sarah C.; Kohn, Matthew J.; Manning, Craig E.

    2015-10-01

    The maximum-pressure Psbnd T conditions (Pmax- T) and prograde Psbnd T paths of exhumed subduction-related metamorphic rocks are compared to predictions of Psbnd T conditions from computational thermal models of subduction systems. While the range of proposed models encompasses most estimated Pmax- T conditions, models predict temperatures that are on average colder than those recorded by exhumed rocks. In general, discrepancies are greatest for Pmax < 2 GPa, where only a few of the highest-T model paths overlap petrologic observations and model averages are 100-300 °C colder than average conditions recorded by rocks. Prograde Psbnd T paths similarly indicate warmer subduction than typical models. Both petrologic estimates and models have inherent biases. Petrologic analysis may overestimate temperatures at Pmax where overprinting occurs during exhumation, although Psbnd T paths suggest that relatively warm conditions are experienced by rocks on the prograde subduction path. Models may underestimate temperatures at depth by neglecting shear heating, hydration reactions and fluid and rock advection. Our compilation and comparison suggest that exhumed high-P rocks provide a more accurate constraint on Psbnd T conditions within subduction zones, and that those conditions may closely represent the subduction geotherm. While exhumation processes in subduction zones require closer petrologic scrutiny, the next generation of models should more comprehensively incorporate all sources of heat. Subduction-zone thermal structures from currently available models appear to be inaccurate, and this mismatch has wide-reaching implications for our understanding of global geochemical cycles, the petrologic structure of subduction zones, and fluid-rock interactions and seismicity within subduction zones.

  20. Structure of six anhydrous molecular salts assembled from noncovalent associations between carboxylic acids and bis-N-imidazoles

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Guo, Ming; Wang, Daqi

    2012-08-01

    Six crystalline organic acid-base adducts derived from bis(N-imidazolyl) and carboxylic acids (3,5-dinitrobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, and phthalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. The six compounds are all organic salts. In salts 1, 2, 4, 5, and 6 the corresponding bis(imidazole) derivatives are diprotonated, while in 3, the corresponding bis(imidazole) derivative is only monoprotonated. All supramolecular architectures of the salts 1-6 involve extensive Nsbnd H⋯O, Osbnd H⋯O, CH⋯O, and CH2⋯O hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. All the salts displayed 3D framework structures under the cooperation of these weak interactions. The results presented herein indicate that the strength and directionality of the N+sbnd H⋯O-, Osbnd H⋯O, and Nsbnd H⋯N hydrogen bonds between carboxylic acids and ditopic imidazoles are sufficient to bring about the formation of binary organic salts.

  1. Exploring Salt Bridge Structures of Gas-Phase Protein Ions using Multiple Stages of Electron Transfer and Collision Induced Dissociation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhe; Browne, Shaynah J.; Vachet, Richard W.

    2014-04-01

    The gas-phase structures of protein ions have been studied by electron transfer dissociation (ETD) and collision-induced dissociation (CID) after electrospraying these proteins from native-like solutions into a quadrupole ion trap mass spectrometer. Because ETD can break covalent bonds while minimally disrupting noncovalent interactions, we have investigated the ability of this dissociation technique together with CID to probe the sites of electrostatic interactions in gas-phase protein ions. By comparing spectra from ETD with spectra from ETD followed by CID, we find that several proteins, including ubiquitin, CRABP I, azurin, and β-2-microglobulin, appear to maintain many of the salt bridge contacts known to exist in solution. To support this conclusion, we also performed calculations to consider all possible salt bridge patterns for each protein, and we find that the native salt bridge pattern explains the experimental ETD data better than nearly all other possible salt bridge patterns. Overall, our data suggest that ETD and ETD/CID of native protein ions can provide some insight into approximate location of salt bridges in the gas phase.

  2. Exploring Salt Bridge Structures of Gas-Phase Protein Ions using Multiple Stages of Electron Transfer and Collision Induced Dissociation

    PubMed Central

    Zhang, Zhe; Browne, Shaynah J.; Vachet, Richard W.

    2014-01-01

    The gas-phase structures of protein ions have been studied by electron transfer dissociation (ETD) and collision-induced dissociation (CID) after electrospraying these proteins from native-like solutions into a quadrupole ion trap mass spectrometer. Because ETD can break covalent bonds while minimally disrupting non-covalent interactions, we have investigated the ability of this dissociation technique together with CID to probe the sites of electrostatic interactions in gas phase protein ions. By comparing spectra from ETD with spectra from ETD followed by CID, we find that several proteins, including ubiquitin, CRABP I, azurin, and β-2-microglobulin, appear to maintain many of the salt bridge contacts known to exist in solution. To support this conclusion, we also performed calculations to consider all possible salt bridge patterns for each protein, and we find that the native salt bridge pattern explains the experimental ETD data better than nearly all other possible salt bridge patterns. Overall, our data suggest that ETD and ETD/CID of native protein ions can provide some insight into approximate location of salt bridges in the gas phase. PMID:24496600

  3. Role of the pore structure of soil and rocks in the CO2 exchange between subsurface and atmosphere.

    NASA Astrophysics Data System (ADS)

    Benavente, David; Pla, Concepcion; Cuezva, Soledad; Fernandez-Cortes, Angel; Garcia-Anton, Elena; Alvarez-Gallego, Miriam; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio

    2014-05-01

    Research on CO2 exchange between terrestrial ecosystems and the atmosphere is now one of the hottest scientific topics. The gas-storage capacity of the uppermost part of the vadose zone is widely known and may represent a substantial fraction of the unknown CO2 atmospheric sink. For instance, CO2 levels in caves can reach currently 10-100 times the typical at the surface. The gas composition of subsurface atmospheres (including CO2 and 222Rn) and the soil and rock petrophyisical properties of several cave sites with different kind and thickness of soil and rocks were monitored. Additionally, experimental results of water vapour transfer on porous soil and host rock were obtained to quantify the variation of diffusion vapor diffusivity coefficient under changing air humidity conditions, which are linked to porous materials with an important capacity to adsorb and condensate vapour water. Results of these studies demonstrate that the soil and host rock act as a permeable/impermeable membrane or barrier controlling CO2 gas exchange. Gas exchange depends directly on weather conditions and pore structure properties. Therefore, any change in the structural and textural properties of rocks and soils modifies the exchange of CO2 between the subsurface enviroments and the atmosphere.

  4. Petrology and geochemistry of target rocks from the Bosumtwi impact structure, Ghana, and comparison with Ivory Coast tektites

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian; Reimold, Wolf Uwe; Blum, Joel D.; Chamberlain, C. Page

    1998-06-01

    The 10.5 km diameter Bosumtwi crater in Ghana, West Africa, is the most likely source crater for the Ivory Coast tektites, as the tektites and the crater have the same age (1.07 Ma), and there are close similarities between the isotopic and chemical compositions of the tektites and crater rocks. The crater is excavated in 2.1-2.2 Ga old metasediments and metavolcanics of the Birimian Supergroup. Here we present the first integrated petrographic and geochemical study of rocks from the Bosumtwi impact crater. A variety of target rocks from the Bosumtwi impact structure were selected to represent the major rock types that have been described before, resulting in four groups: shale, phyllite-graywacke, and two different types of granites (from dispersed dikes and from the so-called Pepiakese intrusion at the northeastern side of the crater). These rocks were analyzed for their major and trace element composition and their petrographic characteristics. In addition, representative samples were also analyzed for their O, Sr, and Nd isotopic compositions. The target rocks do not show any unambiguous evidence of shock metamorphism (i.e., planar deformation features, PDFs). Distinct impact-characteristic shock effects (PDFs) were identified only in clasts within suevite-derived melt fragments. The compositional range of the target rocks is significantly wider than that of the Ivory Coast tektites, but overlap the tektite compositions. A best-fit line for the Bosumtwi crater rocks in a Rb-Sr isotope evolution diagram yields an "age" of 1.98 Ga, and an initial 87Sr/ 86Sr ratio of 0.701, which is close to results previously obtained for granitoid intrusions in the Birimian of Ghana. Our Nd isotopic data yield depleted mantle model ages ranging from 2.16 to 2.64 Ga, and ɛ Nd values of -17.2 to -25.9‰. Harmonic least-squares (HMX) mixing calculations were able to reproduce the composition of Ivory Coast tektites from a mixture of Bosumtwi country rocks that include about 70

  5. The structure of salt bridges between Arg+ and Glu- in peptides investigated with 2D-IR spectroscopy: Evidence for two distinct hydrogen-bond geometries

    NASA Astrophysics Data System (ADS)

    Huerta-Viga, Adriana; Amirjalayer, Saeed; Domingos, Sérgio R.; Meuzelaar, Heleen; Rupenyan, Alisa; Woutersen, Sander

    2015-06-01

    Salt bridges play an important role in protein folding and in supramolecular chemistry, but they are difficult to detect and characterize in solution. Here, we investigate salt bridges between glutamate (Glu-) and arginine (Arg+) using two-dimensional infrared (2D-IR) spectroscopy. The 2D-IR spectrum of a salt-bridged dimer shows cross peaks between the vibrational modes of Glu- and Arg+, which provide a sensitive structural probe of Glu-⋯Arg+ salt bridges. We use this probe to investigate a β-turn locked by a salt bridge, an α-helical peptide whose structure is stabilized by salt bridges, and a coiled coil that is stabilized by intra- and intermolecular salt bridges. We detect a bidentate salt bridge in the β-turn, a monodentate one in the α-helical peptide, and both salt-bridge geometries in the coiled coil. To our knowledge, this is the first time 2D-IR has been used to probe tertiary side chain interactions in peptides, and our results show that 2D-IR spectroscopy is a powerful method for investigating salt bridges in solution.

  6. Hydroxy double salt anion exchange kinetics: effects of precursor structure and anion size.

    PubMed

    Kandare, Everson; Hossenlopp, Jeanne M

    2005-05-01

    (1)H NMR spectroscopy and powder X-ray diffraction have been used to explore the details of anion exchange reactions of two layered hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA), nickel zinc hydroxy acetate (NZA), and a related layered material, zinc hydroxy acetate (ZHA), at room temperature (21-22 degrees C). Reactions that followed Avrami-Erofe'ev kinetics with respect to temporal profiles for acetate release, ZCA with butyrate (k = 1.7 x 10(-3) s(-1)), and octanoate (k = 0.79 x 10(-3) s(-1)) anions, as well as ZHA with octanoate (k = 2.6 x 10(-3) s(-1)), demonstrate that rate constants for acetate release are influenced by the exchange anion relative size as well as by the solid precursor structure/composition. The reaction of NZA with octanoate deviated from expected Avrami-Erofe'ev behavior, with evidence for an intermediate species in the solid phase that may influence the rate of acetate release into solution. The reaction of ZCA with formate anions exhibited a unique zeroth-order kinetics release of acetate, providing the possibility of developing tunable nanostructured anion release sources by use of variations in the size of the exchange species. PMID:16851994

  7. Salt-induced changes in the subunit structure of the Bacillus stearothermophilus lipoate acetyltransferase.

    PubMed

    Shigeoka, Yuichi; Fujisawa, Tetsuro; Teshiba, Satoshi; Fukumori, Hisayoshi; Yamamoto, Kohji; Banno, Yutaka; Aso, Yoichi

    2013-01-01

    The Bacillus stearothermophilus lipoate acetyltransferase (E2), composed of sixty identical, subunits is the core component of the pyruvate dehydrogenase complex (PDC). E2 polypeptide is composed of LD, PSBD, and CD domains. Most studies had focused on a truncated E2 that is deficient in LD and PSBD, because CD mainly contributes to maintaining the multimeric structure. We examined salt-induced changes in E2 without truncation and constructed reaction models. We speculate that in the presence of KCl, E2 is dissociated into a monomer and then assembled into an aggregative complex (C(A)) and a quasi-stable complex (C(Q)). C(A) was larger than C(Q), but smaller than intact E2. C(A) and C(Q), were dominant complexes at about neutral pH and at basic pH respectively. PDC, in which PSBD is occupied by other components, and a truncated E2 undergo dissociation only. LD-PSBD region besides CD might then contribute to the partial association of dissociated E2. PMID:23924725

  8. Features of Bayou Choctaw SPR caverns and internal structure of the salt dome.

    SciTech Connect

    Munson, Darrell E.

    2007-07-01

    The intent of this study is to examine the internal structure of the Bayou Choctaw salt dome utilizing the information obtained from graphical representations of sonar survey data of the internal cavern surfaces. Many of the Bayou Choctaw caverns have been abandoned. Some existing caverns were purchased by the Strategic Petroleum Reserve (SPR) program and have rather convoluted histories and complex cavern geometries. In fact, these caverns are typically poorly documented and are not particularly constructive to this study. Only two Bayou Choctaw caverns, 101 and 102, which were constructed using well-controlled solutioning methods, are well documented. One of these was constructed by the SPR for their use while the other was constructed and traded for another existing cavern. Consequently, compared to the SPR caverns of the West Hackberry and Big Hill domes, it is more difficult to obtain a general impression of the stratigraphy of the dome. Indeed, caverns of Bayou Choctaw show features significantly different than those encountered in the other two SPR facilities. In the number of abandoned caverns, and some of those existing caverns purchased by the SPR, extremely irregular solutioning has occurred. The two SPR constructed caverns suggest that some sections of the caverns may have undergone very regular solutioning to form uniform cylindrical shapes. Although it is not usually productive to speculate, some suggestions that point to the behavior of the Bayou Choctaw dome are examined. Also the primary differences in the Bayou Choctaw dome and the other SPR domes are noted.

  9. Characterization of the Reverberation Chamber at the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    2013-01-01

    In 2011 the noise generating capabilities in the reverberation chamber of the Structural Acoustic Loads and Transmission (SALT) facility at NASA Langley Research Center were enhanced with two fiberglass reinforced polyester resin exponential horns, each coupled to Wyle Acoustic Source WAS-3000 airstream modulators. This report describes the characterization of the reverberation chamber in terms of the background noise, diffusivity, sound pressure levels, the reverberation times and the related overall acoustic absorption in the empty chamber and with the acoustic horn(s) installed. The frequency range of interest includes the 80 Hz to 8000 Hz one-third octave bands. Reverberation time and sound pressure level measurements were conducted and standard deviations from the mean were computed. It was concluded that a diffuse field could be produced above the Schroeder frequency in the 400 Hz one-third octave band and higher for all applications. This frequency could be lowered by installing panel diffusers or moving vanes to improve the acoustic modal overlap in the chamber. In the 80 Hz to 400 Hz one-third octave bands a successful measurement will be dependent on the type of measurement, the test configuration, the source and microphone locations and the desired accuracy. It is recommended that qualification measurements endorsed in the International Standards be conducted for each particular application.

  10. White Rock

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 19 April 2002) The Science 'White Rock' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White Rock is neither white nor dense rock. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White Rock and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White Rock could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White Rock deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White Rock deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white rock seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can

  11. Molecular dynamics simulations of the structure of the graphene-ionic liquid/alkali salt mixtures interface.

    PubMed

    Méndez-Morales, Trinidad; Carrete, Jesús; Pérez-Rodríguez, Martín; Cabeza, Óscar; Gallego, Luis J; Lynden-Bell, Ruth M; Varela, Luis M

    2014-07-14

    We performed molecular dynamics simulations of mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate with lithium tetrafluoroborate and potassium tetrafluoroborate between two charged and uncharged graphene walls, in order to analyze the structure of the well-known formation of layers that takes place on liquids under confinement. For this purpose, we studied the molecular density profiles, free energy profiles for bringing lithium and potassium cations from the bulk mixture to the graphene wall and the orientational distributions of imidazolium rings within the first adsorbed layer as a function of salt concentration and electrode potential. The charge densities in the electrodes were chosen to be zero and ±1 e nm(-2), and the salt molar percentages were %salt = 0, 10 and 25. We found that the layered structure extends up to 1-2 nm, where the bulk behaviour is recovered. In addition, whereas for the neutral surface the layers are composed of both ionic species, increasing the electrode potential, the structure changes to alternating cationic and anionic layers leading to an overcompensation of the charge of the previous layer. We also calculated the distribution of angles of imidazolium rings near neutral and charged graphene walls, finding a limited influence of the added salt. In addition, the average tilt of the imidazolium ring within the first layer goes from 36° with respect to a normal vector to the uncharged graphene wall to 62° in the presence of charged walls. The free energy profiles revealed that lithium and potassium ions are adsorbed on the negative surface only for the highest amount of salt, since the free energy barriers for approaching this electrode are considerably higher than kBT. PMID:24871696

  12. Structure and morphology of the top of Precambrian crystalline rocks in the Illinois Basin region

    SciTech Connect

    Sargent, M.L. ); Rupp, J.A. ); Noger, M.C. )

    1992-01-01

    New basement tests and seismic-reflection profiles in the Rough Creek Graben, Wabash Valley Fault System, and other parts of the Illinois Basin have significantly advanced the authors understanding of basement morphology and tectonics. Few details of the paleotopographic component of basement morphology are known, but 100 m or more of local paleotopographic relief is documented in a few places and more than 300 m of relief is known in the western part of the basin. Based on fewer than 50 wells in the Illinois Basin that penetrate Precambrian crystalline basement, it is composed principally of granite and rhyolite porphyry with small amounts of basalt/diabase or andesite. Most of the regional morphology must be projected from structure maps of key Paleozoic horizons, including the top of Middle Ordovician Trenton (Galena), the top of Middle Devonian carbonate (base of New Albany Shale), and other horizons where data are available. The shallowest Precambrian crystalline basement within the Illinois Basin occurs in north-central Illinois where it is [minus]1,000 m MSL. Paleozoic sedimentary fill thickens southward to over 7,000 m in deeper parts of the Rough Creek Graben where crystalline basement has been depressed tectonically and by sediment loading to below [minus]7,000 m MSL. Although trends in Paleozoic strata show continued thickening in the area of the Mississippi Embayment, maximum sediment fill is preserved in the Rough Creek Graben. The general shape of the basin at the level of Precambrian crystalline basement is largely inferred from structure mapped on Paleozoic strata. Half-grabens and other block-faulted features in basement rocks are manifest in small-scale structures near the surface or have no expression in younger strata.

  13. Influence of salt and rinsing protocol on the structure of PAH/PSS polyelectrolyte multilayers.

    PubMed

    Feldötö, Zsombor; Varga, Imre; Blomberg, Eva

    2010-11-16

    A quartz crystal microbalance (QCM) and dual polarization interferometry (DPI) have been utilized to study how the structure of poly(allylamine hydrochloride) (PAH)/poly(styrene sulfonate) (PSS) multilayers is affected by the rinsing method (i.e., the termination of polyelectrolyte adsorption). The effect of the type of counterions used in the deposition solution was also investigated, and the polyelectrolyte multilayers were formed in a 0.5 M electrolyte solution (NaCl and KBr). From the measurements, it was observed that thicker layers were obtained when using KBr in the deposition solution than when using NaCl. Three different rinsing protocols have been studied: (i) the same electrolyte solution as used during multilayer formation, (ii) pure water, and (iii) first a salt solution (0.5 M) and then pure water. When the multilayer with PAH as the outermost layer was exposed to pure water, an interesting phenomenon was discovered: a large change in the energy dissipation was measured with the QCM. This could be attributed to the swelling of the layer, and from both QCM and DPI it is obvious that only the outermost PAH layer swells (to a thickness of 25-30 nm) because of a decrease in ionic strength and hence an increase in intra- and interchain repulsion, whereas the underlying layers retain a very rigid and compact structure with a low water content. Interestingly, the outermost PAH layer seems to obtain very similar thicknesses in water independent of the electrolyte used for the multilayer buildup. Another interesting aspect was that the measured thickness with the DPI evaluated by a single-layer model did not correlate with the estimated thickness from the model calculations performed on the QCM-D data. Thus, we applied a two-layer model to evaluate the DPI data and the results were in excellent agreement with the QCM-D results. To our knowledge, this evaluation of DPI data has not been done previously. PMID:20886835

  14. Corrosion behavior of Ni-based structural materials for electrolytic reduction in lithium molten salt

    NASA Astrophysics Data System (ADS)

    Cho, Soo Haeng; Park, Sung Bin; Lee, Jong Hyeon; Hur, Jin Mok; Lee, Han Soo

    2011-05-01

    In this study, the corrosion behavior of new Ni-based structural materials was studied for electrolytic reduction after exposure to LiCl-Li 2O molten salt at 650 °C for 24-216 h under an oxidizing atmosphere. The new alloys with Ni, Cr, Al, Si, and Nb as the major components were melted at 1700 °C under an inert atmosphere. The melt was poured into a preheated metallic mold to prepare an as-cast alloy. The corrosion products and fine structures of the corroded specimens were characterized by scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS), and X-ray diffraction (XRD). The corrosion products of as cast and heat treated low Si/high Ti alloys were Cr 2O 3, NiCr 2O 4, Ni, NiO, and (Al,Nb,Ti)O 2; those of as cast and heat treated high Si/low Ti alloys were Cr 2O 3, NiCr 2O 4, Ni, and NiO. The corrosion layers of as cast and heat treated low Si/high Ti alloys were continuous and dense. However, those of as cast and heat treated high Si/low Ti alloys were discontinuous and cracked. Heat treated low Si/high Ti alloy showed the highest corrosion resistance among the examined alloys. The superior corrosion resistance of the heat treated low Si/high Ti alloy was attributed to the addition of an appropriate amount of Si, and the metallurgical evaluations were performed systematically.

  15. Crystal and molecular structures of twelve salts from isopropylamine and different organic acids

    NASA Astrophysics Data System (ADS)

    Wen, Xianhong; Zhang, Huan; Xu, Kai; Sun, JiaHui; Ye, Jiaying; Jin, Shouwen; Wang, Daqi

    2015-08-01

    Twelve isopropylamine derived supramolecular complexes isopropylamine: (m-toluic acid) [(Hipa)+ ṡ (mtua-), mtua- = m-toluate] (1), isopropylamine: (p-toluic acid) [(Hipa)+ ṡ (ptua-), ptua- = p-toluate] (2), isopropylamine: (p-methoxybenzoic acid) [(Hipa)+ ṡ (pmba-), pmba- = p-methoxybenzoate] (3), (isopropylamine): (3,4-methylenedioxybenzoic acid) [(Hipa)+ ṡ (mba)-, mba = 3,4-methylenedioxybenzoate] (4), (isopropylamine): (2-methyl-2-phenoxypropanoic acid) [(Hipa)+ ṡ (mpa-), mpa- = 2-methyl-2-phenoxypropionate] (5), (isopropylamine): (4-chlorophenoxyacetic acid) [(Hipa)+ ṡ (cpa-), cpa- = 4-chlorophenoxyacetate] (6), (isopropylamine): (3,5-dinitrobenzoic acid) [(Hipa)+ ṡ (dnba-), dnba- = 3,5-dinitrobenzoate] (7), (isopropylamine): (2-furoic acid) [(Hipa)+ ṡ (fura-), fura- = 2-furoate] (8), (isopropylamine): (1-hydroxy-2-naphthoic acid) [(Hipa)+ ṡ (hna), hna = 1-hydroxy-2-naphthoate] (9), (isopropylamine): (4-nitrophthalic acid) [(Hipa)2+ ṡ (npa2-), npa2- = 4-nitrophthalate] (10), (isopropylamine)2: (2,5-bis-isopropylcarbamoyl-terephthalic acid): 2H2O [(Hipa)2+ ṡ (bta2-) ṡ 2H2O, bta2- = 2,5-bis-isopropylcarbamoyl-terephthalate] (11), and (isopropylamine)2: (1,5-naphthalenedisulfonic acid) [(Hipa)2+ ṡ (nds2-), nds2- = 1,5-naphthalenedisulfonate] (12) were synthesized and structurally characterized by X-ray crystallography. All supramolecular architectures of 1-12 involve extensive classical hydrogen bonds as well as other non-covalent interactions. The results presented herein indicate that the strength and directionality of the Nsbnd H⋯O, Osbnd H⋯O, and Osbnd H⋯S hydrogen bonds between the acidic components and isopropylamine are sufficient to bring about the formation of binary organic salts. The role of weak and strong non-covalent interactions in the crystal packing is ascertained. These weak interactions combined, the complexes 1-12 displayed 1D-3D framework structure.

  16. Assessment of natural radioactivity levels in rocks and their relationships with the geological structure of Johor state, Malaysia.

    PubMed

    Alnour, I A; Wagiran, H; Ibrahim, N; Hamzah, S; Elias, M S; Laili, Z; Omar, M

    2014-01-01

    The distribution of natural radionuclides ((238)U, (232)Th and (40)K) and their radiological hazard effect in rocks collected from the state of Johor, Malaysia were determined by gamma spectroscopy using a high-purity germanium detector. The highest values of (238)U, (232)Th and (40)K activity concentrations (67±6, 85±7 and 722±18 Bg kg(-1), respectively) were observed in the granite rock. The lowest concentrations of (238)U and (232)Th (2±0.1 Bq kg(-1) for (238)U and 2±0.1 Bq kg(-1) for (232)Th) were observed in gabbro rock. The lowest concentration of (40)K (45±2 Bq kg(-1)) was detected in sandstone. The radium equivalent activity concentrations for all rock samples investigated were lower than the internationally accepted value of 370 Bq kg(-1). The highest value of radium equivalent in the present study (239±17 Bq kg(-1)) was recorded in the area of granite belonging to an acid intrusive rock geological structure. The absorbed dose rate was found to range from 4 to 112 nGy h(-1). The effective dose ranged from 5 to 138 μSv h(-1). The internal and external hazard index values were given in results lower than unity. The purpose of this study is to provide information related to radioactivity background levels and the effects of radiation on residents in the study area under investigation. Moreover, the relationships between the radioactivity levels in the rocks within the geological structure of the studied area are discussed. PMID:23965286

  17. Progress in Studying Salt Secretion from the Salt Glands in Recretohalophytes: How Do Plants Secrete Salt?

    PubMed Central

    Yuan, Fang; Leng, Bingying; Wang, Baoshan

    2016-01-01

    To survive in a saline environment, halophytes have evolved many strategies to resist salt stress. The salt glands of recretohalophytes are exceptional features for directly secreting salt out of a plant. Knowledge of the pathway(s) of salt secretion in relation to the function of salt glands may help us to change the salt-tolerance of crops and to cultivate the extensive saline lands that are available. Recently, ultrastructural studies of salt glands and the mechanism of salt secretion, particularly the candidate genes involved in salt secretion, have been illustrated in detail. In this review, we summarize current researches on salt gland structure, salt secretion mechanism and candidate genes involved, and provide an overview of the salt secretion pathway and the asymmetric ion transport of the salt gland. A new model recretohalophyte is also proposed. PMID:27446195

  18. Rockfall source characterization at high rock walls in complex geological settings by photogrammetry, structural analysis and DFN techniques

    NASA Astrophysics Data System (ADS)

    Agliardi, Federico; Riva, Federico; Galletti, Laura; Zanchi, Andrea; Crosta, Giovanni B.

    2016-04-01

    Rockfall quantitative risk analysis in areas impended by high, subvertical cliffs remains a challenge, due to the difficult definition of potential rockfall sources, event magnitude scenarios and related probabilities. For this reasons, rockfall analyses traditionally focus on modelling the runout component of rockfall processes, whereas rock-fall source identification, mapping and characterization (block size distribution and susceptibility) are over-simplified in most practical applications, especially when structurally complex rock masses are involved. We integrated field and remote survey and rock mass modelling techniques to characterize rock masses and detect rockfall source in complex geo-structural settings. We focused on a test site located at Valmadrera, near Lecco (Southern Alps, Italy), where cliffs up to 600 m high impend on a narrow strip of Lake Como shore. The massive carbonates forming the cliff (Dolomia Principale Fm), normally characterized by brittle structural associations due to their high strength and stiffness, are here involved in an ENE-trending, S-verging kilometre-scale syncline. Brittle mechanisms associated to folding strongly controlled the nature of discontinuities (bedding slip, strike-slip faults, tensile fractures) and their attributes (spacing and size), as well as the spatial variability of bedding attitude and fracture intensity, with individual block sizes up to 15 m3. We carried out a high-resolution terrestrial photogrammetric survey from distances ranging from 1500 m (11 camera stations from the opposite lake shore, 265 pictures) to 150 m (28 camera stations along N-S directed boat routes, 200 pictures), using RTK GNSS measurements for camera station geo-referencing. Data processing by Structure-from-Motion techniques resulted in detailed long-range (1500 m) and medium-range (150 to 800 m) point clouds covering the entire slope with maximum surface point densities exceeding 50 pts/m2. Point clouds allowed a detailed

  19. Novel imidazolium and imidazolinium salts containing the 9-nickelafluorenyl anion--synthesis, structures and reactivity.

    PubMed

    Buchalski, Piotr; Pacholski, Roman; Chodkiewicz, Krzysztof; Buchowicz, Włodzimierz; Suwińska, Kinga; Shkurenko, Aleksander

    2015-04-28

    Investigation of the properties of carbene complexes is one of the most important fields of modern coordination chemistry. In this paper, we propose the convenient synthesis of NHC-nickel compounds. The 9-nickelafluorenyllithium complex reacts with imidazolium or imidazolinium salts to afford 9-nickelafluorenyl-NHC salts via ionic metathesis with very good yields (66-92%). These compounds can be isomerised at elevated temperatures to give Ni-NHC complexes with excellent yields (88-91%), probably via nickel mediated hydrogen transfer to the biphenyl moiety. In this reaction, the nickelacyclic ring itself serves as a base in the deprotonation of the carbene precursor. DFT calculations show the thermodynamic instability of the synthesized salts, with Gibbs free energy differences for 1 of -84 kJ mol(-1) at 298 K and -167 kJ mol(-1) at 374 K. The obtained salts and carbene complexes are relatively air and moisture stable in the solid state. PMID:25786198

  20. The information content of high-frequency seismograms and the near-surface geologic structure of "hard rock" recording sites

    USGS Publications Warehouse

    Cranswick, E.

    1988-01-01

    Due to hardware developments in the last decade, the high-frequency end of the frequency band of seismic waves analyzed for source mechanisms has been extended into the audio-frequency range (>20 Hz). In principle, the short wavelengths corresponding to these frequencies can provide information about the details of seismic sources, but in fact, much of the "signal" is the site response of the nearsurface. Several examples of waveform data recorded at "hard rock" sites, which are generally assumed to have a "flat" transfer function, are presented to demonstrate the severe signal distortions, including fmax, produced by near-surface structures. Analysis of the geology of a number of sites indicates that the overall attenuation of high-frequency (>1 Hz) seismic waves is controlled by the whole-path-Q between source and receiver but the presence of distinct fmax site resonance peaks is controlled by the nature of the surface layer and the underlying near-surface structure. Models of vertical decoupling of the surface and nearsurface and horizontal decoupling of adjacent sites on hard rock outcrops are proposed and their behaviour is compared to the observations of hard rock site response. The upper bound to the frequency band of the seismic waves that contain significant source information which can be deconvolved from a site response or an array response is discussed in terms of fmax and the correlation of waveform distortion with the outcrop-scale geologic structure of hard rock sites. It is concluded that although the velocity structures of hard rock sites, unlike those of alluvium sites, allow some audio-frequency seismic energy to propagate to the surface, the resulting signals are a highly distorted, limited subset of the source spectra. ?? 1988 Birkha??user Verlag.

  1. Effects of rock mineralogy and pore structure on stress-dependent permeability of shale samples.

    PubMed

    Al Ismail, Maytham I; Zoback, Mark D

    2016-10-13

    We conducted pulse-decay permeability experiments on Utica and Permian shale samples to investigate the effect of rock mineralogy and pore structure on the transport mechanisms using a non-adsorbing gas (argon). The mineralogy of the shale samples varied from clay rich to calcite rich (i.e. clay poor). Our permeability measurements and scanning electron microscopy images revealed that the permeability of the shale samples whose pores resided in the kerogen positively correlated with organic content. Our results showed that the absolute value of permeability was not affected by the mineral composition of the shale samples. Additionally, our results indicated that clay content played a significant role in the stress-dependent permeability. For clay-rich samples, we observed higher pore throat compressibility, which led to higher permeability reduction at increasing effective stress than with calcite-rich samples. Our findings highlight the importance of considering permeability to be stress dependent to achieve more accurate reservoir simulations especially for clay-rich shale reservoirs.This article is part of the themed issue 'Energy and the subsurface'. PMID:27597792

  2. Genetic diversity and structure in the Endangered Allen Cays Rock Iguana, Cyclura cychlura inornata

    PubMed Central

    Aplasca, Andrea C.; Iverson, John B.; Welch, Mark E.; Colosimo, Giuliano

    2016-01-01

    The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (<4 ha each). However, populations of unknown origin were recently discovered on four additional cays. To investigate patterns of genetic variation among these populations, we analyzed nuclear and mitochondrial markers for 268 individuals. Analysis of three mitochondrial gene regions (2,328 bp) and data for eight nuclear microsatellite loci indicated low genetic diversity overall. Estimates of effective population sizes based on multilocus genotypes were also extremely low. Despite low diversity, significant population structuring and variation in genetic diversity measures were detected among cays. Genetic data confirm the source population for an experimentally translocated population while raising concerns regarding other, unauthorized, translocations. Reduced heterozygosity is consistent with a documented historical population decline due to overharvest. This study provides the first range-wide genetic analysis of this subspecies. We suggest strategies to maximize genetic diversity during ongoing recovery including additional translocations to establish assurance populations and additional protective measures for the two remaining natural populations. PMID:26989628

  3. Genetic diversity and structure in the Endangered Allen Cays Rock Iguana, Cyclura cychlura inornata.

    PubMed

    Aplasca, Andrea C; Iverson, John B; Welch, Mark E; Colosimo, Giuliano; Hekkala, Evon R

    2016-01-01

    The Endangered Allen Cays Rock Iguana (Cyclura cychlura inornata) is endemic to the Allen Cays, a tiny cluster of islands in the Bahamas. Naturally occurring populations exist on only two cays (<4 ha each). However, populations of unknown origin were recently discovered on four additional cays. To investigate patterns of genetic variation among these populations, we analyzed nuclear and mitochondrial markers for 268 individuals. Analysis of three mitochondrial gene regions (2,328 bp) and data for eight nuclear microsatellite loci indicated low genetic diversity overall. Estimates of effective population sizes based on multilocus genotypes were also extremely low. Despite low diversity, significant population structuring and variation in genetic diversity measures were detected among cays. Genetic data confirm the source population for an experimentally translocated population while raising concerns regarding other, unauthorized, translocations. Reduced heterozygosity is consistent with a documented historical population decline due to overharvest. This study provides the first range-wide genetic analysis of this subspecies. We suggest strategies to maximize genetic diversity during ongoing recovery including additional translocations to establish assurance populations and additional protective measures for the two remaining natural populations. PMID:26989628

  4. Effect of the structure of bile salt aggregates on the binding of aromatic guests and the accessibility of anions.

    PubMed

    Li, Rui; Carpentier, Eric; Newell, Edward D; Olague, Lana M; Heafey, Eve; Yihwa, Chang; Bohne, Cornelia

    2009-12-15

    The binding of naphthalene (Np), 1-ethylnaphthalene (EtNp), acenaphthene (AcN), and 1-naphthyl-1-ethanol (NpOH) as guests to the aggregates of sodium cholate (NaCh), taurocholate (NaTC), deoxycholate (NaDC), and deoxytaurocholate (NaTDC) was studied with the objective of determining how the structure of the bile salts affects the binding dynamics of guests and quenchers with the bile salt aggregates. Time-resolved and steady-state fluorescence experiments were used to determine the binding efficiency of the guests with the aggregates and were also employed to investigate the quenching of the singlet excited state of the guests by iodide anions. Quenching studies of the triplet excited states using laser flash photolysis were employed to determine the accessibility to the aggregate of nitrite anions, used as quenchers, and the dissociation rate constants of the guests from the bile salt aggregates. The binding efficiency of the guests to NaDC and NaTDC is higher than for NaCh and NaTC, and the protection efficiency is also higher for NaDC and NaTDC, in line with the larger aggregates formed for the latter bile salts. The formation of aggregates is in part driven by the structure of the guest, where an increased protection efficiency and residence time can be achieved by the introduction of short alkyl substituents (AcN or EtNp vs Np). NpOH was shown to be located in a very different environment in all four bile salts when compared to AcN, EtNp, and Np, suggesting that hydrogen bonding plays an important role in the formation of the aggregate around NpOH. PMID:19606836

  5. Estimates of salt dynamical motion and hydrocarbon trapping around a salt diapir in the Gulf of Mexico

    SciTech Connect

    Lerche, I.; Petersen, K.

    1996-12-31

    On the basis of lithology determinations assessed from seismic, together with the geological situation inferred around a salt structure in the Viosca Knoll region of the Gulf of Mexico, quantitative analysis of both salt and sediment motion, together with thermal effects and hydrocarbon kinetic modeling, would seem to imply that: the salt stock rose syndepositionally with sedimentation throughout Jurassic time, with the salt top maintained at the sediment/water interface; at Cretaceous time a competent chalk deposition terminated salt`s rise; and Miocene and later deposition raised the temperature regime around the salt so that hydrocarbon generation occurred from about 10 MYBP until present day, with the gas window being entered about 3--5 MYBP. A secondary target for hydrocarbon retention is the Jurassic sediments with the salt mushroom as a tight sealing cover, and the salt stock as a lateral updip boundary impeding migration. Downhole information to improve the likelihood of estimating economic reserves of liquid condensate or gas hydrocarbons for this diapir, and possibly others, includes: vitrinite reflectance with depth to better assess paleotemperatures; downhole temperatures (corrected) with depth, giving a better assessment of the local thermal anomaly with depth; fluid pressure measurements with depth, which provide information on fluid-flow through formations, together with inferred excess heating and maturation of sediments with time caused by lower than normal thermal conductivities; and TOC and Rock-Eval pyrolysis measurements with depth to estimate regional and local source potential for hydrocarbon production.

  6. Synthesis and structure of 1-methyl-2,3-dihydro-1,2,4-triazolium salts and their free bases

    SciTech Connect

    Pinson, V.V.; Krustalev, V.A.; Matveeva, Z.M.; Zelenin, K.N.

    1985-04-01

    1-Methyl-2,3-dihydro-1,2,4-triazolium iodides can be obtained by reacting methylhydrazones with S-methylthioamide hydriodides, by condensing 2-methylamidrazone hydriodides with aldehydes and ketones, or by reacting methyl iodide with 1-alkylidene(or arylidene) benzamidrazones. In solutions these salts are capable of undergoing tautomerism to 1-alkylidene(or arylidene)-2-methylamidrazone hydriodides. The influence of the structural factors on the position of the tautomeric equilibrium has been studied. The free bases obtained by neutralization of the respective salts by an alkali metal hydroxide are heretofore undescribed 1-alkylidene(or arylidene)-2-methylhydrazidoimines or 4-triazolines, depending on their structure. Under the action of oxygen, these compounds are readily oxidized to substituted 1-methyl-1,2,4-triazoles with heating.

  7. Pattern formation of down-built salt structures: insights from 3D numerical models

    NASA Astrophysics Data System (ADS)

    Fernandez, Naiara; Kaus, Boris

    2015-04-01

    Many salt diapirs are thought to have formed as a result of down-building, which implies that the top of the diapir remained close to the surface during sediment deposition. This process is largely three-dimensional and in order to better understand what controls the patterns that form as a result of this down-building process, we here perform three-dimensional numerical models and compare the results with analytical models. In our models, we vary several parameters such as initial salt thickness, sedimentation rate, salt viscosity, salt-sediment viscosity contrast as well as the density of sediments. Down-building of three-dimensional diapirs only occurs for a certain range of parameters and is favored by lower sediment/salt viscosity contrasts and sedimentation rates in agreement with analytical predictions and findings from previous 2D models. However, the models show that the sedimentation rate has an additional effect on the formation and evolution of three-dimensional diapir patterns. At low sedimentation rates, salt ridges that form during early model stages remain preserved at later stages as well. For higher sedimentation rates, the initial salt ridges break up and form finger-like diapirs at the junction of salt ridges, which results in different salt exposure patterns at the surface. Once the initial pattern of diapirs is formed, higher sedimentation rate can also result in covered diapirs if the diapir extrusion velocity is insufficiently large. We quantify the effect of sedimentation rate on the number of diapirs exposed at the surface as well as on their spacing. In some cases, this final pattern is distinctly different from the initial polygonal pattern. We also study the extrusion of salt through time in the simulations, and show that it can be related to the geometries of the sedimentary layers surrounding the diapirs. Acknowledgements. Funding was provided by the European Research Council under the European Community's Seventh Framework Program

  8. Retrospective salt tectonics

    SciTech Connect

    Jackson, M.P.A.

    1996-12-31

    The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ crystallization, osmotic pressures, and expansive crystallization. Gradually data from oil exploration constrained speculation. The effects of buoyancy versus orogeny were debated, contact relations were characterized, salt glaciers were discovered, and the concepts of downbuilding and differential loading were proposed as diapiric mechanisms. The fluid era (1933-{approximately}1989) was dominated by the view that salt tectonics resulted from Rayleigh-Taylor instabilities in which a dense fluid overburden having negligible yield strength sinks into a less dense fluid salt layer, displacing it upward. Density contrasts, viscosity contrasts, and dominant wavelengths were emphasized, whereas strength and faulting of the overburden were ignored. During this era, palinspastic reconstructions were attempted; salt upwelling below thin overburdens was recognized; internal structures of mined diapirs were discovered; peripheral sinks, turtle structures, and diapir families were comprehended; flow laws for dry salt were formulated; and contractional belts on divergent margins and allochthonous salt sheets were recognized. The 1970s revealed the basic driving force of salt allochthons, intrasalt minibasins, finite strains in diapirs, the possibility of thermal convection in salt, direct measurement of salt glacial flow stimulated by rainfall, and the internal structure of convecting evaporites and salt glaciers. The 1980`s revealed salt rollers, subtle traps, flow laws for damp salt, salt canopies, and mushroom diapirs.

  9. Local structuring factors of invertebrate communities in ephemeral freshwater rock pools and the influence of more permanent water bodies in the region

    USGS Publications Warehouse

    Jocque, M.; Graham, T.; Brendonck, L.

    2007-01-01

    We used three isolated clusters of small ephemeral rock pools on a sandstone flat in Utah to test the importance of local structuring processes on aquatic invertebrate communities. In the three clusters we characterized all ephemeral rock pools (total: 27) for their morphometry, and monitored their water quality, hydrology and community assemblage during a full hydrocycle. In each cluster we also sampled a set of more permanent interconnected freshwater systems positioned in a wash, draining the water from each cluster of rock pools. This design allowed additional testing for the potential role of more permanent water bodies in the region as source populations for the active dispersers and the effect on the community structure in the rock pools. Species richness and community composition in the rock pools correlated with level of permanence and the ammonia concentration. The length of the rock pool inundation cycle shaped community structure, most probably by inhibiting colonization by some taxa (e.g. tadpoles and insect larvae) through developmental constraints. The gradient in ammonia concentrations probably reflects differences in primary production. The more permanent water bodies in each wash differed both environmentally and in community composition from the connected set of rock pools. A limited set of active dispersers was observed in the rock pools. Our findings indicate that aquatic invertebrate communities in the ephemeral rock pools are mainly structured through habitat permanence, possibly linked with biotic interactions and primary production. ?? 2007 Springer Science+Business Media B.V.

  10. Structure of metavolcanic and metasedimentary rocks in the Matterhorn-Twin Peaks area, Saddlebag Lake pendant, eastern Sierra Nevada, California

    SciTech Connect

    Lahren, M.M.; Schweickert, R.A. . Dept. of Geological Sciences)

    1993-04-01

    Recent structural mapping shows that the rocks in the Matterhorn-Twin Peaks area comprise parts of seven east-dipping and east-facing thrust sheets. These sheets and their bounding thrusts all appear to dip beneath the structurally higher, Glenberry Lake thrust sheet, and are intruded discordantly in Spiller, Cattle, Horse canyons by the 86-Ma Cathedral Peak Granodiorite of the Tuolumne Intrusive Suite (TIS). The lowest exposed sheet contains rocks that probably correlate with the Upper Triassic and Lower Jurassic Koip sequence. The overlying six sheets contain a distinctive assemblage of metamorphosed calcareous sandstone, siltstone, mudstone, limestone, and interbedded silicic tuffs of the Horse Canyon sequence, possibly of Middle Jurassic age. Thrust faults expose mylonitic and schistose metavolcanic rocks, and the two lowest are marked by slices of periodotite up to several tens of meters in length. Locally, conglomerates with clasts of peridotite, quartzite, and metavolcanic rocks are associated with the peridotite slices. A sill-like body of granitic orthogneiss occurs along one of the thrusts. Stretching lineations in the most intensely deformed rocks plunge steeply to the east, suggesting dominantly dip slip displacement. The origin(s) of the peridotite slices are enigmatic, but the authors provisionally interpret the peridotite to have been intermittently exposed at the surface during thrusting, and the conglomerates to have been thrust-derived. Age of thrusting is unknown, but probably was between Middle Jurassic and Middle Cretaceous. The structure of this area argues against major deformation due to intrusion or return flow along the margins of the TIS.

  11. The role of structural diagenesis in faulting and fracturing of upper crustal rocks

    NASA Astrophysics Data System (ADS)

    Laubach, Stephen

    2015-04-01

    Fluid flow in fractured rock is increasingly important in recovering water and hydrocarbon supplies and geothermal energy, in predicting flow of pollutants underground, in engineering structures, and in understanding large-scale crustal behavior. Structural diagenesis, the study of the relationships between deformation or deformational structures and chemical changes to sediments, can help unlock knowledge about the low-temperature realm of sedimentary basins that is of great intrinsic and practical interest. The effects of structural diagenetic interactions on fault and fracture attributes are illustrated by meter- to decimeter-displacement oblique-slip faults cut latest Precambrian lithic arkose to feldspathic litharenite and Cambrian quartz arenite sandstones in NW Scotland. Despite common slip and thermal histories during faulting, the two sandstone units have different fault-core and damage-zone attributes, including fracture length and aperture distributions, and location of quartz deposits. Fault cores are narrow (less than 1 meter), low-porosity cataclasite in lithic arkose/feldspathic litharenites. Damage zone-parallel opening-mode fractures are long (meters or more) with narrow ranges of lengths and apertures, are mostly isolated, have sparse quartz cement, and are open. In contrast, quartz arenites, despite abundant quartz cement, have fault cores that contain porous breccia and dense, striated slip zones. Damage-zone fractures have lengths ranging from meters to centimeters or less, but with distributions skewed to short fractures, and have power-law aperture distributions. Owing to extensive quartz cement, they tend to be sealed. These attributes reflect inhibited authigenic quartz accumulation on feldspar and lithic grains, which are unfavorable precipitation substrates, and favored accumulation on detrital quartz. In quartz breccia, macropores >0.04 mm wide persist where surrounded by slow-growing euhedral quartz. Differences in quartz occurrence and

  12. Ion aggregation in high salt solutions. V. Graph entropy analyses of ion aggregate structure and water hydrogen bonding network.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2016-05-28

    Dissolved ions in water tend to form polydisperse ion aggregates such as ion pairs, relatively compact ion clusters, and even spatially extended ion networks with increasing salt concentration. Combining molecular dynamics simulation and graph theoretical analysis methods, we recently studied morphological structures of ion aggregates with distinctively different characteristics. They can be distinguished from each other by calculating various spectral graph theoretical properties such as eigenvalues and eigenvectors of adjacency matrices of ion aggregates and water hydrogen-bonding networks, minimum path lengths, clustering coefficients, and degree distributions. Here, we focus on percolation and graph entropic properties of ion aggregates and water hydrogen-bonding networks in high salt solutions. Ion network-forming K(+) and SCN(-) ions at high concentrations show a percolating behavior in their aqueous solutions, but ion cluster-forming ions in NaCl solutions do not show such a transition from isolated ion aggregates to percolating ion-water mixture morphology. Despite that the ion aggregate structures are strikingly different for either cluster- or network-forming ions in high salt solutions, it is interesting that the water structures remain insensitive to the electrostatic properties, such as charge densities and polydentate properties, of dissolved ions, and morphological structures of water H-bonding networks appear to be highly robust regardless of the nature and concentration of salt. We anticipate that the present graph entropy analysis results would be of use in understanding a variety of anomalous behaviors of interfacial water around biomolecules as well as electric conductivities of high electrolyte solutions. PMID:27250298

  13. Ion aggregation in high salt solutions. V. Graph entropy analyses of ion aggregate structure and water hydrogen bonding network

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Ho; Cho, Minhaeng

    2016-05-01

    Dissolved ions in water tend to form polydisperse ion aggregates such as ion pairs, relatively compact ion clusters, and even spatially extended ion networks with increasing salt concentration. Combining molecular dynamics simulation and graph theoretical analysis methods, we recently studied morphological structures of ion aggregates with distinctively different characteristics. They can be distinguished from each other by calculating various spectral graph theoretical properties such as eigenvalues and eigenvectors of adjacency matrices of ion aggregates and water hydrogen-bonding networks, minimum path lengths, clustering coefficients, and degree distributions. Here, we focus on percolation and graph entropic properties of ion aggregates and water hydrogen-bonding networks in high salt solutions. Ion network-forming K+ and SCN- ions at high concentrations show a percolating behavior in their aqueous solutions, but ion cluster-forming ions in NaCl solutions do not show such a transition from isolated ion aggregates to percolating ion-water mixture morphology. Despite that the ion aggregate structures are strikingly different for either cluster- or network-forming ions in high salt solutions, it is interesting that the water structures remain insensitive to the electrostatic properties, such as charge densities and polydentate properties, of dissolved ions, and morphological structures of water H-bonding networks appear to be highly robust regardless of the nature and concentration of salt. We anticipate that the present graph entropy analysis results would be of use in understanding a variety of anomalous behaviors of interfacial water around biomolecules as well as electric conductivities of high electrolyte solutions.

  14. Semantic modeling of the structural and process entities during plastic deformation of crystals and rocks

    NASA Astrophysics Data System (ADS)

    Babaie, Hassan; Davarpanah, Armita

    2016-04-01

    We are semantically modeling the structural and dynamic process components of the plastic deformation of minerals and rocks in the Plastic Deformation Ontology (PDO). Applying the Ontology of Physics in Biology, the PDO classifies the spatial entities that participate in the diverse processes of plastic deformation into the Physical_Plastic_Deformation_Entity and Nonphysical_Plastic_Deformation_Entity classes. The Material_Physical_Plastic_Deformation_Entity class includes things such as microstructures, lattice defects, atoms, liquid, and grain boundaries, and the Immaterial_Physical_Plastic_Deformation_Entity class includes vacancies in crystals and voids along mineral grain boundaries. The objects under the many subclasses of these classes (e.g., crystal, lattice defect, layering) have spatial parts that are related to each other through taxonomic (e.g., Line_Defect isA Lattice_Defect), structural (mereological, e.g., Twin_Plane partOf Twin), spatial-topological (e.g., Vacancy adjacentTo Atom, Fluid locatedAlong Grain_Boundary), and domain specific (e.g., displaces, Fluid crystallizes Dissolved_Ion, Void existsAlong Grain_Boundary) relationships. The dynamic aspect of the plastic deformation is modeled under the dynamical Process_Entity class that subsumes classes such as Recrystallization and Pressure_Solution that define the flow of energy amongst the physical entities. The values of the dynamical state properties of the physical entities (e.g., Chemical_Potential, Temperature, Particle_Velocity) change while they take part in the deformational processes such as Diffusion and Dislocation_Glide. The process entities have temporal parts (phases) that are related to each other through temporal relations such as precedes, isSubprocessOf, and overlaps. The properties of the physical entities, defined under the Physical_Property class, change as they participate in the plastic deformational processes. The properties are categorized into dynamical, constitutive

  15. Forceful emplacement of the Eureka Valley-Joshua Flat-Beer Creek composite pluton into a structural basin in eastern California; internal structure and wall rock deformation

    NASA Astrophysics Data System (ADS)

    Morgan, Sven; Law, Richard; de Saint Blanquat, Michel

    2013-11-01

    Anisotropy of Magnetic Susceptibility parameters have been analyzed at 311 locations in the Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton of eastern California. The large amount of data has allowed for the AMS parameters to be contoured using techniques that both reveal map-scale trends and emphasize small-scale differences. The contour maps suggest that magnetic susceptibility is dominantly controlled by composition of the magma but may also be affected by emplacement-related strain as the magma chamber inflated and forced the wall rocks outward. Pluton construction involved two major pulses of different composition magmas that were emplaced sequentially but with overlapping periods of crystallization. The magmas initially intruded as sill-like bodies into a structural basin. The magnetic foliation of the pluton cuts across internal magmatic contacts on the map scale and is parallel to local contacts between the pluton and surrounding metasedimentary wall rocks. The magnetic fabric is similar in orientation and symmetry to intense flattening strains recorded in the aureole rocks. The metasedimentary wall rocks have been shortened between 60 and 70% and this strain magnitude is approximately equal on the west, south, and east margins of the pluton. Strain in the wall rocks is dominantly flattening and concentrated into a narrow (1 km wide) inner aureole. Mapping of bedding/cleavage intersection lineations south of the pluton indicates that the magma made room for itself by translating the wall rocks outward and rotating the already inward dipping wall rocks of the structural basin to sub-vertical. Stretching of the inner aureole around an expanding magma chamber was responsible for the intense shortening. Limited data on the Marble Canyon pluton to the south of the EJB pluton indicates a very similar emplacement process.

  16. Higher plant Ca(2+)-ATPase: primary structure and regulation of mRNA abundance by salt.

    PubMed Central

    Wimmers, L E; Ewing, N N; Bennett, A B

    1992-01-01

    Calcium-dependent regulatory mechanisms participate in diverse developmentally, hormonally, and environmentally regulated processes, with the precise control of cytosolic Ca2+ concentration being critical to such mechanisms. In plant cells, P-type Ca(2+)-ATPases localized in the plasma membrane and the endoplasmic reticulum are thought to play a central role in regulating cytoplasmic Ca2+ concentrations. Ca(2+)-ATPase activity has been identified in isolated plant cell membranes, but the protein has not been characterized at the molecular level. We have isolated a partial-length cDNA (LCA1) and a complete genomic clone (gLCA13) encoding a putative endoplasmic reticulum-localized Ca(2+)-ATPase in tomato. The deduced amino acid sequence specifies a protein (Lycopersicon Ca(2+)-ATPase) of 1048 amino acids with a molecular mass of 116 kDa, eight probable transmembrane domains, and all of the highly conserved functional domains common to P-type cation-translocating ATPases. In addition, the protein shares approximately 50% amino acid sequence identify with animal sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases but less than 30% identity with other P-type ATPases. Genomic DNA blot hybridization analysis indicates that the Lycopersicon Ca(2+)-ATPase is encoded by a single gene. RNA blot hybridization analysis indicates the presence of three transcript sizes in root tissue and a single, much less abundant, transcript in leaves. Lycopersicon Ca(2+)-ATPase mRNA levels increase dramatically upon a 1-day exposure to 50 mM NaCl. Thus this report describes the primary structure of a higher-plant Ca(2+)-ATPase and the regulation of its mRNA abundance by salt stress. Images PMID:1384045

  17. Divisions of potential fracture permeability, based on distribution of structures and lineaments, in sedimentary rocks of the Rocky Mountains-High Plains region, Western United States

    USGS Publications Warehouse

    Cooley, Maurice E.

    1986-01-01

    Fractures--joints and faults--affect the movement of fluids in rocks. Fracture permeability is important in sedimentary rocks that otherwise transmit water slowly, particularly limestone, dolomite, and fine-grained sandstone. A map of fracture traces may be used in assessing the spatial distribution of groundwater. The principal map in this report (scale 1:2,500 ,000) shows geologic structures and lineaments that affect the distribution of fracture traces in the sedimentary rocks of the High Plains and some adjacent areas. Potential fracture permeability is indicated on the map by 5 divisions, ranging from division 1 (smallest) to division 5 (largest potential fracture permeability). Geologic structure was the basis for delineating division boundaries. Generally, rocks in structurally uplifted areas and near conspicuous lineaments are more extensively fractured and have greater secondary permeability than rocks of structural basins. (USGS)

  18. Salt effects on the structure and internal dynamics of superhelical DNAs studied by light scattering and Brownian dynamics.

    PubMed Central

    Hammermann, M; Steinmaier, C; Merlitz, H; Kapp, U; Waldeck, W; Chirico, G; Langowski, J

    1997-01-01

    Using laser light scattering, we have measured the static and dynamic structure factor of two different superhelical DNAs, p1868 (1868 bp) and simian virus 40 (SV40) (5243 bp), in dilute aqueous solution at salt concentrations between 1 mM and 3 M NaCl. For both DNA molecules, Brownian dynamics (BD) simulations were also performed, using a previously described model. A Fourier mode decomposition procedure was used to compute theoretical light scattering autocorrelation functions (ACFs) from the BD trajectories. Both measured and computed autocorrelation functions were then subjected to the same multiexponential decomposition procedure. Simulated and measured relaxation times as a function of scattering angle were in very good agreement. Similarly, computed and measured static structure factors and radii of gyration agreed within experimental error. One main result of this study is that the amplitudes of the fast-relaxing component in the ACF show a peak at 1 M salt concentration. This nonmonotonic behavior might be caused by an initial increase in the amplitudes of internal motions due to diminishing long-range electrostatic repulsions, followed by a decrease at higher salt concentration due to a compaction of the structure. PMID:9370461

  19. Salt tectonics on Venus

    SciTech Connect

    Wood, C.A.; Amsbury, D.

    1986-05-01

    The discovery of a surprisingly high deuterium/hydrogen ratio on Venus immediately led to the speculation that Venus may have once had a volume of surface water comparable to that of the terrestrial oceans. The authors propose that the evaporation of this putative ocean may have yielded residual salt deposits that formed various terrain features depicted in Venera 15 and 16 radar images. By analogy with models for the total evaporation of the terrestrial oceans, evaporite deposits on Venus should be at least tens to hundreds of meters thick. From photogeologic evidence and in-situ chemical analyses, it appears that the salt plains were later buried by lava flows. On Earth, salt diapirism leads to the formation of salt domes, anticlines, and elongated salt intrusions - features having dimensions of roughly 1 to 100 km. Due to the rapid erosion of salt by water, surface evaporite landforms are only common in dry regions such as the Zagros Mountains of Iran, where salt plugs and glaciers exist. Venus is far drier than Iran; extruded salt should be preserved, although the high surface temperature (470/sup 0/C) would probably stimulate rapid salt flow. Venus possesses a variety of circular landforms, tens to hundreds of kilometers wide, which could be either megasalt domes or salt intrusions colonizing impact craters. Additionally, arcurate bands seen in the Maxwell area of Venus could be salt intrusions formed in a region of tectonic stress. These large structures may not be salt features; nonetheless, salt features should exist on Venus.

  20. Bile salts of vertebrates: structural variation and possible evolutionary significance[S

    PubMed Central

    Hofmann, Alan F.; Hagey, Lee R.; Krasowski, Matthew D.

    2010-01-01

    Biliary bile salt composition of 677 vertebrate species (103 fish, 130 reptiles, 271 birds, 173 mammals) was determined. Bile salts were of three types: C27 bile alcohols, C27 bile acids, or C24 bile acids, with default hydroxylation at C-3 and C-7. C27 bile alcohols dominated in early evolving fish and amphibians; C27 bile acids, in reptiles and early evolving birds. C24 bile acids were present in all vertebrate classes, often with C27 alcohols or with C27 acids, indicating two evolutionary pathways from C27 bile alcohols to C24 bile acids: a) a ‘direct’ pathway and b) an ‘indirect’ pathway with C27 bile acids as intermediates. Hydroxylation at C-12 occurred in all orders and at C-16 in snakes and birds. Minor hydroxylation sites were C-1, C-2, C-5, C-6, and C-15. Side chain hydroxylation in C27 bile salts occurred at C-22, C-24, C-25, and C-26, and in C24 bile acids, at C-23 (snakes, birds, and pinnipeds). Unexpected was the presence of C27 bile alcohols in four early evolving mammals. Bile salt composition showed significant variation between orders but not between families, genera, or species. Bile salt composition is a biochemical trait providing clues to evolutionary relationships, complementing anatomical and genetic analyses. PMID:19638645

  1. Major structural controls on the distribution of pre-Tertiary rocks, Nevada Test Site vicinity, southern Nevada

    SciTech Connect

    Cole, J.C.

    1998-10-23

    The lateral and vertical distributions of Proterozoic and Paleozoic sedimentary rocks in southern Nevada are the combined products of original stratigraphic relationships and post-depositional faults and folds. This map compilation shows the distribution of the pre-Tertiary rocks in the region including and surrounding the Nevada Test Site. It is based on considerable new evidence from detailed geologic mapping, biostratigraphic control, sedimentological analysis, and a review of regional map relationships. Proterozoic and Paleozoic rocks of the region record paleogeographic transitions between continental shelf depositional environments on the east and deeper-water slope-facies depositional environments on the west. Middle Devonian and Mississippian sequences, in particular, show strong lateral facies variations caused by contemporaneous changes in the western margin of North America during the Antler orogeny. Sections of rock that were originally deposited in widely separated facies localities presently lie in close proximity. These spatial relationships chiefly result from major east- and southeast-directed thrusts that deformed the region in Permian or later time. Somewhat younger contractional structures are identified within two irregular zones that traverse the region. These folds and thrusts typically verge toward the west and northwest and overprint the relatively simple pattern of the older contractional terranes. Local structural complications are significant near these younger structures due to the opposing vergence and due to irregularities in the previously folded and faulted crustal section. Structural and stratigraphic discontinuities are identified on opposing sides of two north-trending fault zones in the central part of the compilation region north of Yucca Flat. The origin and significance of these zones are enigmatic because they are largely covered b Tertiary and younger deposits. These faults most likely results from significant lateral

  2. Integrating topography, hydrology and rock structure in weathering rate models of spring watersheds

    NASA Astrophysics Data System (ADS)

    Pacheco, Fernando A. L.; Van der Weijden, Cornelis H.

    2012-03-01

    SummaryWeathering rate models designed for watersheds combine chemical data of discharging waters with morphologic and hydrologic parameters of the catchments. At the spring watershed scale, evaluation of morphologic parameters is subjective due to difficulties in conceiving the catchment geometry. Besides, when springs emerge from crystalline massifs, rock structure must be accounted in formulas describing the area of minerals exposed to the percolating fluids, for a realistic evaluation of the rates. These particular features are not included in the available approaches and for that reason a new model was developed, coined THROW model. This is a lumped approach that integrates (T)opography, (H)ydrology, (RO)ck structure and (W)eathering in a single algorithm. The study area comprises several stream watersheds and spring sites of the Vouga River basin (northern Portugal), shaped on granites. Firstly, the THROW model couples a terrain modeling analysis with hydrologic models based on discharge rates, to determine hydraulic conductivities (K), effective porosities (ne) and annual recharges (Vr) at the stream watershed scale. Subsequently, these parameters are used in a water balance model to estimate concomitant groundwater travel times (t). The mean K [(4.7 ± 3.2) × 10-7 m s-1] and ne [(2.0 ± 1.3) × 10-2] values are adopted as proxies for the spring watersheds and a firm regression equation is defined between time and stream watershed area (A). Secondly, two more runs of terrain modeling analysis are executed to extrapolate morphologic parameters for the spring watersheds. The first run hinges on scaling properties of the drainage networks, known as Horton laws, and is used to scale watershed areas across stream orders (i). The scaling function is described by another regression equation. The second run evaluates the order of a spring watershed, defined as equivalent order (ieq) and equated to the mean order of the surrounding stream watersheds. Having

  3. Allelic Variants in Arhgef11 via the Rho-Rock Pathway Are Linked to Epithelial–Mesenchymal Transition and Contributes to Kidney Injury in the Dahl Salt-Sensitive Rat

    PubMed Central

    Jia, Zhen; Johnson, Ashley C.; Wang, Xuexiang; Guo, Zibiao; Dreisbach, Albert W.; Lewin, Jack R.; Kyle, Patrick B.; Garrett, Michael R.

    2015-01-01

    Previously, genetic analyses identified that variants in Arhgef11 may influence kidney injury in the Dahl salt-sensitive (S) rat, a model of hypertensive chronic kidney disease. To understand the potential mechanism by which altered expression and/or protein differences in Arhgef11 could play a role in kidney injury, stably transduced Arhgef11 knockdown cell lines as well as primary cultures of proximal tubule cells were studied. Genetic knockdown of Arhgef11 in HEK293 and NRK resulted in reduced RhoA activity, decreased activation of Rho-ROCK pathway, and less stress fiber formation versus control, similar to what was observed by pharmacological inhibition (fasudil). Primary proximal tubule cells (PTC) cultured from the S exhibited increased expression of Arhgef11, increased RhoA activity, and up regulation of Rho-ROCK signaling compared to control (small congenic). The cells were also more prone (versus control) to TGFβ-1 induced epithelial-mesenchymal transition (EMT), a hallmark feature of the development of renal interstitial fibrosis, and characterized by development of spindle shape morphology, gene expression changes in EMT markers (Col1a3, Mmp9, Bmp7, and Ocln) and increased expression of N-Cadherin and Vimentin. S derived PTC demonstrated a decreased ability to uptake FITC-albumin compared to the small congenic in vitro, which was confirmed by assessment of albumin re-uptake in vivo by infusion of FITC-albumin and immunofluorescence imaging. In summary, these studies suggest that genetic variants in the S form of Arhgef11 via increased expression and/or protein activity play a role in promoting kidney injury in the S rat through changes in cell morphology (Rho-Rock and/or EMT) that impact the function of tubule cells. PMID:26172442

  4. Population structure within an alpine archipelago: strong signature of past climate change in the New Zealand rock wren (Xenicus gilviventris).

    PubMed

    Weston, K A; Robertson, B C

    2015-09-01

    Naturally subdivided populations such as those occupying high-altitude habitat patches of the 'alpine archipelago' can provide significant insight into past biogeographical change and serve as useful models for predicting future responses to anthropogenic climate change. Among New Zealand's alpine taxa, phylogenetic studies support two major radiations: the first correlating with geological forces (Pliocene uplift) and the second with climatic processes (Pleistocene glaciations). The rock wren (Xenicus gilviventris) is a threatened alpine passerine belonging to the endemic New Zealand wren family (Acanthisittidae). Rock wren constitute a widespread, naturally fragmented population, occurring in patches of suitable habitat over c. 900 m in altitude throughout the length of the South Island, New Zealand. We investigated the relative role of historical geological versus climatic processes in shaping the genetic structure of rock wren (N = 134) throughout their range. Using microsatellites combined with nuclear and mtDNA sequence data, we identify a deep north-south divergence in rock wren (3.7 ± 0.5% at cytochrome b) consistent with the glacial refugia hypothesis whereby populations were restricted in isolated refugia during the Pleistocene c. 2 Ma. This is the first study of an alpine vertebrate to test and provide strong evidence for the glacial refugia hypothesis as an explanation for the low endemicity central zone known as the biotic 'gap' in the South Island of New Zealand. PMID:26342535

  5. The early life of a Salt Giant: syndepositional basement faulting in the Zechstein of NE Netherlands.

    NASA Astrophysics Data System (ADS)

    Urai, Janos L.; Raith, Alexander F.; Michalón, Raúl

    2016-04-01

    The Zechstein of NE Netherlands is often thought to have been deposited in a tectonically quiet environment. In this study we attempted to test this hypothesis using very high quality 3D seismic and well data, mapping in detail the seismic reflections of the thick, anhydrite - dolomite Z III stringer, encased in thick layers of rock salt as a strain marker. We focused on the Friesland platform which was only weakly affected by later salt tectonics. First results show that the stringer contains (i) a regional network of thicker zones (TZ) which are interpreted to reflect the interaction of anhydrite dewatering pathways and localized dissolution of salt below fracture systems in the stringer, and (ii) a network of zones where the stringers are absent, interpreted as ruptures formed by salt flow. These ruptures in many cases mark a clear vertical shift of the sub-horizontal stringer. Mapping of the base salt and top salt reflectors shows that the ruptures often coincide with faults at base Zechstein level, and that the thickness of the post-stringer rock salt layers is thicker where the stringers are lower, while the total salt thickness is relatively constant. We interpret these structures as evidence for movement on the faults at base salt, during Zechstein times, suggesting that Zechstein deposition was syn-tectonic.

  6. Linking external and internal salt geometries - a key to understanding salt dynamics

    NASA Astrophysics Data System (ADS)

    Kukla, Peter; Urai, Janos

    2014-05-01

    Considering the growing importance of salt in the energy, food and waste disposal industries, this paper reviews the status quo and major developments in salt research over the last decade. As a way forward in order to close identified gaps in knowledge, an integrated salt basin evaluation concept is proposed appreciating both external and internal geometries and properties. Examples of key studies in the Central European Basin and the South Oman Salt basin show that such a model may improve our understanding of the multi-scale processes operating in salt terrains. The workflow proposed allows to better asses (i) the initiation and maintenance of salt dynamics, (ii) the evolution of the internal structure of evaporites during halokinesis in salt giants, (iii) the coupling of processes in the evaporites and the salt's under- and overburden. It will lead to a better integration of the different data sets and resulting models, which will provide new insights into the structural evolution of salt giants. Finally it will also stimulate new concepts for (i) the initiation dynamics of halokinesis, (ii) the rheology and mechanics of the evaporites by brittle and ductile processes, (iii) the coupling of processes in the evaporites and the under- and overburden, and (iv) the impact of the layered evaporite rheology on the structural evolution. As an outlook for future research to be initiated in salt terrains we still need to improve our database on evaporite rocks especially the ones which take changes of properties in time into account. This includes for example the dependencies of thermal and mechanical properties on changes in strain, pressure and temperature or external and internal geometry changes relating to slow geological processes. Also geomechanical modelling efforts can be significantly improved by making full use of the data available on the effects of water, and some of the discrepancies seen in experimental data on different salts can probably be explained in

  7. Self-organized rock textures and multiring structure in the Duolun crater

    NASA Technical Reports Server (NTRS)

    Wu, Siben; Zhang, Jiayun

    1992-01-01

    The Duolun impact crater is a multiring basin located 200 km north of Beijing. From the center to the edge of the crater there are innermost rim, inner ring, outer rim, and outermost ring. Recently, we have found some self-organized textures or chaos phenomena in shock-metamorphic rocks from the Duolun impact crater, such as turbulence in matrices of impact glass, oscillatory zoning, or chemical chaos of spherulites in spherulitic splashed breccia, fractal wavy textures or self-similar wavy textures with varied scaling in impact glass, and crystallite beams shaped like Lorentz strange attractors. The rare phenomena indicate that the shock-metamorphic rocks from Duolun crater are formed far from equilibrium. If impact cratering generates momentarily under high-pressure and superhigh-temperature, occurrence of those chaos phenomena in shock-metamorphic rock is not surprising.

  8. Isolation and structural and electronic characterization of salts of the decamethylferrocene dication.

    PubMed

    Malischewski, M; Adelhardt, M; Sutter, J; Meyer, K; Seppelt, K

    2016-08-12

    Ferrocene and its decamethyl derivative [Cp*2Fe] are the most common standards for nonaqueous electrochemical investigations because of their well-defined and only mildly solvent-dependent reversible Fe(II)/Fe(III) redox couple. Higher oxidation states have only rarely been studied. We report the isolation and crystallographic and spectroscopic characterization of surprisingly stable Fe(IV) salts of the [Cp*2Fe](2+) dication, produced by oxidation of [Cp*2Fe] with AsF5, SbF5, or ReF6 in neat sulfur dioxide as well as [XeF](Sb2F11) in neat hydrogen fluoride. The Sb2F11(-) salt exhibits a metallocene with the expected mutually parallel arrangements of the Cp* rings, whereas the As2F11(-), AsF6(-), SbF6(-), and ReF6(-) salts manifest tilt angles ranging from 4° to 17°. Both (57)Fe Mössbauer spectroscopy and superconducting quantum interference device magnetization studies reveal identical d-orbital splitting with an S = 1, (3)E ground state based on the 3d electronic configuration e2g (3)a1g (1) of all [Cp*2Fe](2+) salts. PMID:27516596

  9. RELATIONSHIPS OF NITROGEN LOADINGS AND PHYSICAL CHARACTERISTICS WITH PLANT STRUCTURE IN NEW ENGLAND SALT MARSHES

    EPA Science Inventory

    Nitrogen enrichment is hypothesized to cause competitive displacement of dominant plants in New England salt marshes. In this Narragansett Bay, RI, field survey, we examined the vascular plant species richness and the extent, density, and height of Spartina species in ten marshe...

  10. Synthesis, crystal structure, spectral characterization and fluorescence studies of salts of α-mangostin with APIs

    NASA Astrophysics Data System (ADS)

    Satyanarayana Reddy, J.; Ravikumar, N.; Gaddamanugu, Gopikrishna; Naresh, K. N.; Rajan, S. S.; Anand Solomon, K.

    2013-05-01

    α-Mangostin is a naturally occurring oxygenated xanthonoid isolated from the mangosteen tree (Garcinia mangostana). We report the molecular salts of α-mangostin with the active pharmaceutical ingredients (APIs) metformin (anti-diabetic) and piperazine (anti-helminthic) obtained by solvent assisted grinding method as well as solution crystallization method based on the ΔpKa criterion. The synergistic pharmaceutically active α-mangostin-metformin molecular salt and α-mangostin-hemipiperazine ethanol solvate were characterized by the single crystal X-ray diffraction (SCXRD), vibrational spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The fluorescence properties of the molecular salts are obtained by fluorescence spectroscopy. The molecules in both the crystal forms are stabilized by N+sbnd H⋯N, Osbnd H⋯O-, N+sbnd H⋯O and N+sbnd H⋯O-, Osbnd H⋯O hydrogen bonding interactions. In the FT-IR spectra characteristic peaks are observed for the protonated amine (sbnd NH2+) group piperazinium dication (sbnd NH+) respectively indicating formation salts.

  11. Ion aggregation in high salt solutions. IV. Graph-theoretical analyses of ion aggregate structure and water hydrogen bonding network.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2015-09-14

    Ions in high salt solutions form a variety of ion aggregates, from ion pairs to clusters and networks. Their influences on water hydrogen bonding (H-bonding) network structures have long been of great interest. Recently, we have shown that the morphological structures of ion aggregates can be analyzed by using a spectral graph analysis theory, where each ion cluster or ion network is represented by a properly defined graph with edges and vertices. Here, to further examine the network properties of ion aggregates and water H-bonding networks in high salt solutions, we consider a few representative graph-theoretical descriptors: clustering coefficient, minimum path length, global efficiency, and degree distribution of ion aggregates. From the molecular dynamics trajectories, these graph theoretical properties of ion aggregates and water structures in NaCl and kosmotropic solutions are calculated and shown to be strongly dependent on the two types of ion aggregate structures, i.e., ion cluster and ion network. Ion clusters in high NaCl solutions exhibit typical behaviors of scale free network. The corresponding graph theoretical properties of ion networks in high KSCN solutions are notably different from those of NaCl ion clusters and furthermore they are very similar to those of water hydrogen-bonding network. The present graph-theoretical analysis results indicate that the high solubility limits of KSCN and other ion-network-forming salts might originate from their ability to form a large scale morphological network that can be intertwined with co-existing water H-bonding network. Furthermore, it is shown that the graph-theoretical properties of water H-bonding network structures do not strongly depend on the nature of dissolved ions nor on the morphological structures of ion aggregates, indicating that water's H-bonding interaction and network-forming capability are highly robust. We anticipate that the present graph-theoretical analysis results of high salt

  12. Ion aggregation in high salt solutions. IV. Graph-theoretical analyses of ion aggregate structure and water hydrogen bonding network

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Ho; Cho, Minhaeng

    2015-09-01

    Ions in high salt solutions form a variety of ion aggregates, from ion pairs to clusters and networks. Their influences on water hydrogen bonding (H-bonding) network structures have long been of great interest. Recently, we have shown that the morphological structures of ion aggregates can be analyzed by using a spectral graph analysis theory, where each ion cluster or ion network is represented by a properly defined graph with edges and vertices. Here, to further examine the network properties of ion aggregates and water H-bonding networks in high salt solutions, we consider a few representative graph-theoretical descriptors: clustering coefficient, minimum path length, global efficiency, and degree distribution of ion aggregates. From the molecular dynamics trajectories, these graph theoretical properties of ion aggregates and water structures in NaCl and kosmotropic solutions are calculated and shown to be strongly dependent on the two types of ion aggregate structures, i.e., ion cluster and ion network. Ion clusters in high NaCl solutions exhibit typical behaviors of scale free network. The corresponding graph theoretical properties of ion networks in high KSCN solutions are notably different from those of NaCl ion clusters and furthermore they are very similar to those of water hydrogen-bonding network. The present graph-theoretical analysis results indicate that the high solubility limits of KSCN and other ion-network-forming salts might originate from their ability to form a large scale morphological network that can be intertwined with co-existing water H-bonding network. Furthermore, it is shown that the graph-theoretical properties of water H-bonding network structures do not strongly depend on the nature of dissolved ions nor on the morphological structures of ion aggregates, indicating that water's H-bonding interaction and network-forming capability are highly robust. We anticipate that the present graph-theoretical analysis results of high salt

  13. Modeling Spatial Structure of Rock Fracture Surfaces Before and After Shear Test: A Method for Estimating Morphology of Damaged Zones

    NASA Astrophysics Data System (ADS)

    Babanouri, Nima; Karimi Nasab, Saeed

    2015-05-01

    This paper deals with the structural analysis of rock fracture roughness, and accordingly, a method is developed for estimating/predicting the post-shearing 3D geometry of the fracture surface. For this purpose, surfaces of three natural rock fractures were digitized and studied before and after the direct shear test. The variogram analysis of the surfaces indicated a strong non-linear trend in the topography data. Hence, the spatial variability of the rock fracture surfaces was decomposed to: one deterministic component, characterized by a high-order polynomial representing the large-scale undulations, and one stochastic component, described by the variogram of residuals representing the small-scale roughness. Using an image-processing technique, a total of 343 damage zones with different sizes, shapes, initial roughness characteristics, local stress fields, and/or asperity strength values were spatially located and clustered. In order to characterize the overall spatial structure of the degraded zones, the concept of the `pseudo-zonal variogram' was introduced. The results showed that the spatial continuity at the damage zones increases due to the asperity degradation. The increase in the variogram range is anisotropic and tends to be higher along the shearing. Consequently, the direction of maximum continuity rotates towards the shear direction. After modeling the evolution of the spatial structure with shearing and detecting boundaries of the degraded areas, a methodology was presented to provide a regression-kriging estimate of the morphology of sheared surfaces. The proposed method can be considered as a cost-free and reasonably accurate alternative to expensive techniques of scanning the rock fracture surface after the shear test.

  14. Quantum Calculations on Salt Bridges with Water: Potentials, Structure, and Properties

    SciTech Connect

    Liao, Sing; Green, Michael E.

    2011-01-01

    Salt bridges are electrostatic links between acidic and basic amino acids in a protein; quantum calculations are used here to determine the energetics and other properties of one form of these species, in the presence of water molecules. The acidic groups are carboxylic acids (aspartic and glutamic acids); proteins have two bases with pK above physiological pH: one, arginine, with a guanidinium basic group, the other lysine, which is a primary amine. Only arginine is modeled here, by ethyl guanidinium, while propionic acid is used as a model for either carboxylic acid. The salt bridges are accompanied by 0-12 water molecules; for each of the 13 systems, the energy-bond distance relation, natural bond orbitals (NBO), frequency calculations allowing thermodynamic corrections to room temperature, and dielectric constant dependence, were all calculated. The water molecules were found to arrange themselves in hydrogen bonded rings anchored to the oxygens of the salt bridge components. This was not surprising in itself, but it was found that the rings lead to a periodicity in the energy, and to a 'water addition' rule. The latter shows that the initial rings, with four oxygen atoms, become five member rings when an additional water molecule becomes available, with the additional water filling in at the bond with the lowest Wiberg index, as calculated using NBO. The dielectric constant dependence is the expected hyperbola, and the fit of the energy to the inverse dielectric constant is determined. There is an energy periodicity related to ring formation upon addition of water molecules. When 10 water molecules have been added, all spaces near the salt bridge are filled, completing the first hydration shell, and a second shell starts to form. The potentials associated with salt bridges depend on their hydration, and potentials assigned without regard to local hydration are likely to cause errors as large as or larger than kBT, thus suggesting a serious problem if these

  15. Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

    USGS Publications Warehouse

    Lee, S.R.; Horton, J.W., Jr.; Walker, R.J.

    2006-01-01

    The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270?? higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events. ?? The Meteoritical Society, 2006.

  16. Structural changes in and the wear of the rock cutting element of a bulldozer during operation under the North conditions

    NASA Astrophysics Data System (ADS)

    Vinokurov, G. G.; Yakovleva, S. P.; Kychkin, A. K.; Vasil'Eva, M. I.; Struchkov, N. F.; Fedorov, M. V.

    2009-10-01

    The phenomenon of accelerated wear of a ripper crown in a digging machine (bulldozer) under the North operating conditions is studied. The elemental composition, microstructure, microhardness of the crown metal and the wear surface relief characteristics are determined. It is found that, under complex heat-force conditions of loading during the exploitation of cryolite rocks, the metal in the active surface of the rock cutting element undergoes intense softening as a result of the formation of a secondary structure, namely, frictioninduced sorbite. As a result of an insufficient level of the wear resistance of the crown metal and its plasticization, the traces of abrasive wear become deeper and plastic impact-abrasive wear takes place.

  17. Characteristics, vertical structures, and heat/salt transports of mesoscale eddies in the southeastern tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Yu, Weidong; Yuan, Yeli; Zhao, Xia; Wang, Fan; Chen, Gengxin; Liu, Lin; Duan, Yongliang

    2015-10-01

    Satellite altimetry sea surface height measurements reveal high mesoscale eddy activity in the southeastern tropical Indian Ocean (SETIO). In this study, the characteristics of mesoscale eddies in the SETIO are investigated by analyzing 564 cyclonic eddy (CE) tracks and 695 anticyclonic eddy (AE) tracks identified from a new version of satellite altimetry data with a daily temporal resolution. The mean radius, lifespan, propagation speed, and distance of CEs (AEs) are 149 (153) km, 50 (46) days, 15.3 (16.6) cm s-1, and 651 (648) km, respectively. Some significant differences exist in the eddy statistical characteristics between the new-version daily altimeter data and the former weekly data. Mean vertical structures of anomalous potential temperature, salinity, geostrophic current, as well as heat and salt transports of the composite eddies, are estimated by analyzing Argo profile data matched to altimeter-detected eddies. The composite analysis shows that eddy-induced ocean anomalies are mainly confined in the upper 300 dbar. In the eddy core, CE (AE) could induce a cooling (warming) of 2°C between 60 and 180 dbar and maximum positive (negative) salinity anomalies of 0.1 (-0.3) psu in the upper 50 (110) dbar. The meridional heat transport induced by the composite CE (AE) is southward (northward), whereas the salt transport of CE (AE) is northward (southward). Most of the meridional heat and salt transports are carried in the upper 300 dbar.

  18. Structure of conjugated bile salt-fatty acid-monoglyceride mixed colloids: Studies by small-angle neutron scattering

    SciTech Connect

    Hjelm, R.P.; Schteingart, C.D.; Hofmann, A.F.; Thiyagarajan, P.

    2000-01-20

    The structures of particles found in isotropic phases of mixed surfactant systems consisting of conjugated bile salts and fatty lipids were assessed using small-angle neutron scattering. The conjugated bile salts were either cholylglycine or chenodeoxycholylglycine. The fatty lipids were mixtures of oleate and oleic acid either alone or with monoolein. The scattering data suggested that both particle interactions and polydispersity must be modeled in these systems. Particle interactions were modeled using the reduced mean spherical approximation and the decoupling approximation. Maximum entropy was used to characterize the polydispersity. A self-consistent analysis of the scattering was arrived at by making an initial estimate of particle size and shape using derivative-log and Guinier analysis and refining the estimates by analyzing the particle interactions and polydispersity and iterating. There are sufficient similarities in the particle morphologies of these and other conjugated bile salt-fatty lipid systems to suggest a common mode of self-assembly. These solutions are models for bile in the bilary system and intestine content during triglyceride digestion; the common themes of self-assembly have implications for the physiology of lipid solubilization in bile as well as intestinal absorption of dietary lipids.

  19. Comparative structural reconstruction of the post-breakup succession in conjugated salt and salt-free basins offshore South-America and South-Africa

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2013-04-01

    This project focuses on the post-breakup tectono-stratigraphic development of large offshore basins along the South American and African continental margins that record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. In this study we show a regional comparison between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin, etc). A sequential reconstruction of tectonic and stratigraphic elements of representative geological transects provides a comprehensive basin-to-basin documentation of the influence of key geological parameters controlling ocean and continental margin development. These include the subsidence development through time, sediment input, flux and storage patterns, salt vs. non-salt systems, carbonate-rich vs. clastics-dominated successions and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development.

  20. Osmium-isotope Evidence for a Projectile Component in Impact-melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

    NASA Astrophysics Data System (ADS)

    Lee, S.; Horton, J. W.; Walker, R. J.

    2004-12-01

    The late Eocene Chesapeake Bay impact structure (CBIS) is preserved beneath post-impact sediments on the Atlantic margin of Virginia. This 85-km-diameter complex crater formed on the continental shelf of a passive margin in a layered target consisting of ocean water, Cretaceous and Tertiary sediments (mainly siliciclastic), and crystalline basement rocks. The basement rocks include Neoproterozoic granitoids and felsite as well as gneiss of undetermined age. In May, 2004, the USGS drilled an 823-m test hole in the central uplift of the CBIS at Cape Charles, Va., providing drill cuttings and limited core. The core from 744 to 823 m depth contains crystalline-clast breccia and brecciated gneiss that are distinct from sediment-clast breccias recovered from coreholes in the annular trough of the CBIS. Rocks interpreted to be impact-melt clasts and dikes in the crystalline-clast breccia were sampled for analyses of osmium (Os) concentrations and 187Os/188Os ratios to test for evidence of the projectile. These analyses were conducted on samples from a dike (aphanitic to partly hyaline, ST2440.8C) within a gneissic block, from a block of holocrystalline mafic rock (aphanitic, ST2453.3C), and from a flow-laminated bomb (aphanitic to partly hyaline, ST2570.0C). The Os concentrations and 187Os/188Os ratios for samples ST2440.8C, ST2453.3C and ST2570.0C are 0.928, 0.711 and 0.312 ppb, and 0.15205, 0.15545 and 0.22345, respectively. These values are much higher (Os) or lower (187Os/188Os) than those reported for rocks of the upper continental crust, suggesting a significant contribution of osmium from the projectile in these impact-melt rocks. Moreover, a strong negative correlation between 187Os/188Os and Os for these samples suggests that it may be possible to use mixing curves to calculate the proportions of projectile and target-rock components. Our results from the CBIS contrast with those from the Chicxulub crater, where there is little or no evidence for the

  1. Experimental determination of the relationship between permeability and microfracture-induced damage in bedded salt

    SciTech Connect

    Pfeifle, T.W.

    1998-03-01

    The development of deep underground structures (e.g., shafts, mines, storage and disposal caverns) significantly alters the stress state in the rock near the structure or opening. The effect of such an opening is to concentrate the far-field stress near the free surface. For soft rock such as salt, the concentrating effect of the opening induces deviatoric stresses in the salt that may be large enough to initiate microcracks which then propagate with time. The volume of rock susceptible to damage by microfracturing is often referred to as the disturbed rock zone and, by its nature, is expected to exhibit high permeability relative to that of the native, far-field rock. This paper presents laboratory data that characterize microfracture-induced damage and the effect this damage has on permeability for bedded salt from the Waste Isolation Pilot Plant located in southeastern New Mexico. Damage is induced in the salt through a series of tertiary creep experiments and quantified in terms of dilatant volumetric strain. The permeability of damaged specimens is then measured using nitrogen gas as the permeant. The range in damage investigated included dilatant volumetric strains from less than 0.03 percent to nearly 4.0 percent. Permeability values corresponding to these damage levels ranged from 1 {times} 10{sup {minus}18} m{sup 2} to 1 {times} 10{sup {minus}12} m{sup 2}. Two simple models were fitted to the data for use in predicting permeability from dilatant volumetric strain.

  2. Determination of structural domain boundaries in jointed rock masses: An example from the Songta dam site, China

    NASA Astrophysics Data System (ADS)

    Li, Yanyan; Wang, Qing; Chen, Jianping; Han, Lili; Zhang, Wen; Ruan, Yunkai

    2014-12-01

    This paper presents an application of the Kolmogorov-Smirnov and Wilcoxon rank sum nonparametric statistical tests for identifying structural domain boundaries in jointed rock masses. In the method, the upper hemispherical surface is divided into 100 nearly equal-area windows. The similarity between two samples of joint orientations is measured by comparing the frequencies or the number of joint poles occurring in the windows. Over 2400 joints collected from 8 adjacent exploration tunnels at the Songta dam site in southwest China are used to demonstrate the method. By applying the technique to the study area, structural domain boundaries in the rock mass are determined. Our results suggest that the study area, with an area of approximately 17,850 m2, can be classified into four structural domains. However, the traditional method with the correlation coefficient fails to reveal the structural changes. Since the correlation coefficient is only a measure of strength of the linear relation between two samples, it has limitations in measuring the similarity between joint orientation distributions. A comparison between the proposed method and previous methods indicates that the new technique could provide more reliable results. Besides, the new method can be applied to structural populations with small sample sizes.

  3. Molecular dynamics simulations of the surface tension and structure of salt solutions and clusters.

    PubMed

    Sun, Lu; Li, Xin; Hede, Thomas; Tu, Yaoquan; Leck, Caroline; Ågren, Hans

    2012-03-15

    Sodium halides, which are abundant in sea salt aerosols, affect the optical properties of aerosols and are active in heterogeneous reactions that cause ozone depletion and acid rain problems. Interfacial properties, including surface tension and halide anion distributions, are crucial issues in the study of the aerosols. We present results from molecular dynamics simulations of water solutions and clusters containing sodium halides with the interatomic interactions described by a conventional force field. The simulations reproduce experimental observations that sodium halides increase the surface tension with respect to pure water and that iodide anions reach the outermost layer of water clusters or solutions. It is found that the van der Waals interactions have an impact on the distribution of the halide anions and that a conventional force field with optimized parameters can model the surface tension of the salt solutions with reasonable accuracy. PMID:22352372

  4. A new multicomponent salt of imidazole and tetrabromoterepthalic acid: structural, optical, thermal, electrical transport properties and antibacterial activity along with Hirshfeld surface analysis.

    PubMed

    Dey, Sanjoy Kumar; Saha, Rajat; Singha, Soumen; Biswas, Susobhan; Layek, Animesh; Middya, Somnath; Ray, Partha Pratim; Bandhyopadhyay, Debasis; Kumar, Sanjay

    2015-06-01

    Herein, we report the structural, optical, thermal and electrical transport properties of a new multicomponent salt (TBTA(2-))·2(IM(+))·(water) [TBTA-IM] of tetrabromoterepthalic acid (TBTA) with imidazole (IM). The crystal structure of TBTA-IM is determined by both the single crystal and powder X-ray diffraction techniques. The structural analysis has revealed that the supramolecular charge assisted O(-)⋯HN(+) hydrogen bonding and Br⋯π interactions play the most vital role in formation of this multicomponent supramolecular assembly. The Hirshfeld surface analysis has been carried out to investigate supramolecular interactions and associated 2D fingerprint plots reveal the relative contribution of these interactions in the crystal structure quantitatively. According to theoretical analysis the HOMO-LUMO energy gap of the salt is 2.92 eV. The salt has been characterized by IR, UV-vis and photoluminescence spectroscopic studies. It shows direct optical transition with band gaps of 4.1 eV, which indicates that the salt is insulating in nature. The photoluminescence spectrum of the salt is significantly different from that of TBTA. Further, a comparative study on the antibacterial activity of the salt with respect to imidazole, Gatifloxacin and Ciprofloxacin has been performed. Moreover, the current-voltage (I-V) characteristic of ITO/TBTA-IM/Al sandwich structure exhibits good rectifying property and the electron tunneling process governs the electrical transport mechanism of the device. PMID:25748591

  5. A new multicomponent salt of imidazole and tetrabromoterepthalic acid: Structural, optical, thermal, electrical transport properties and antibacterial activity along with Hirshfeld surface analysis

    NASA Astrophysics Data System (ADS)

    Dey, Sanjoy Kumar; Saha, Rajat; Singha, Soumen; Biswas, Susobhan; Layek, Animesh; Middya, Somnath; Ray, Partha Pratim; Bandhyopadhyay, Debasis; Kumar, Sanjay

    2015-06-01

    Herein, we report the structural, optical, thermal and electrical transport properties of a new multicomponent salt (TBTA2-)·2(IM+)·(water) [TBTA-IM] of tetrabromoterepthalic acid (TBTA) with imidazole (IM). The crystal structure of TBTA-IM is determined by both the single crystal and powder X-ray diffraction techniques. The structural analysis has revealed that the supramolecular charge assisted O-⋯Hsbnd N+ hydrogen bonding and Br⋯π interactions play the most vital role in formation of this multicomponent supramolecular assembly. The Hirshfeld surface analysis has been carried out to investigate supramolecular interactions and associated 2D fingerprint plots reveal the relative contribution of these interactions in the crystal structure quantitatively. According to theoretical analysis the HOMO-LUMO energy gap of the salt is 2.92 eV. The salt has been characterized by IR, UV-vis and photoluminescence spectroscopic studies. It shows direct optical transition with band gaps of 4.1 eV, which indicates that the salt is insulating in nature. The photoluminescence spectrum of the salt is significantly different from that of TBTA. Further, a comparative study on the antibacterial activity of the salt with respect to imidazole, Gatifloxacin and Ciprofloxacin has been performed. Moreover, the current-voltage (I-V) characteristic of ITO/TBTA-IM/Al sandwich structure exhibits good rectifying property and the electron tunneling process governs the electrical transport mechanism of the device.

  6. Microplastic Pollution in Table Salts from China.

    PubMed

    Yang, Dongqi; Shi, Huahong; Li, Lan; Li, Jiana; Jabeen, Khalida; Kolandhasamy, Prabhu

    2015-11-17

    Microplastics have been found in seas all over the world. We hypothesize that sea salts might contain microplastics, because they are directly supplied by seawater. To test our hypothesis, we collected 15 brands of sea salts, lake salts, and rock/well salts from supermarkets throughout China. The microplastics content was 550-681 particles/kg in sea salts, 43-364 particles/kg in lake salts, and 7-204 particles/kg in rock/well salts. In sea salts, fragments and fibers were the prevalent types of particles compared with pellets and sheets. Microplastics measuring less than 200 μm represented the majority of the particles, accounting for 55% of the total microplastics, and the most common microplastics were polyethylene terephthalate, followed by polyethylene and cellophane in sea salts. The abundance of microplastics in sea salts was significantly higher than that in lake salts and rock/well salts. This result indicates that sea products, such as sea salts, are contaminated by microplastics. To the best of our knowledge, this is the first report on microplastic pollution in abiotic sea products. PMID:26486565

  7. Fluid-rock interactions in seismic faults: Implications from the structures and mineralogical and geochemical compositions of drilling cores from the rupture of the 2008 Wenchuan earthquake, China

    NASA Astrophysics Data System (ADS)

    Duan, Qingbao; Yang, Xiaosong; Ma, Shengli; Chen, Jianye; Chen, Jinyu

    2016-01-01

    We describe the structural features and mineralogical and geochemical compositions of the fault rocks recovered from boreholes at the Golden River site on the Yingxiu-Beichuan fault, which activated and slipped along a 240 km-long main surface rupture zone during the 2008 Wenchuan earthquake. The fault, which accommodated co-seismic slip, cuts granitic rocks from the Pengguan complex, in which this earthquake most likely nucleated. Fault rocks, including cohesive cataclasite, unconsolidated breccia and three fault gouges with distinct colors, were identified from the drilling cores. On-going uplift and erosion in the area means that the fault rocks, formed at different depth, were exhumed to the shallow surface during the uplift history of the Longmenshan fault zone. A clear change from fracturing and comminution in the cataclasites and breccia to more pervasive shear/formation of fine grained materials in the gouges has been observed. The gouges are distinct and have accommodated significant displacement in multiple increments of shear. Furthermore, fault rocks recovered from the boreholes display numerous features indicative of fluid infiltration and fluid-rock interaction. Toward the fault core, clay minerals have replaced feldspars. The element enrichment/depletion patterns of the fault rocks show general fluid infiltration trends, such as 1) mobile elements are generally depleted in the fault rocks, 2) the microstructural, mineralogical and geochemical results of the fault rocks consistently indicate that pervasive fluid infiltration and fluid-rock interactions altered feldspars and mafic minerals to clay minerals. The fluid was Mg2 +- and Fe2 +-rich, facilitating formation of chlorite. Isocon analyses further reveal that a large rock volume has been lost, which is attributed to the removal of mobile elements associated with fluid infiltration and perhaps enhanced by pressure solution. These results reflect the accumulated effects of cataclasis and fluid

  8. Hydrocarbon accumulation on rifted Continental Margin - examples of oil migration pathways, west African salt basins

    SciTech Connect

    Blackwelder, B.W.

    1989-03-01

    Examination of the oil fields in the Gabon, Lower Congo, and Cuanza basins allows modeling of oil migration and a more accurate ranking of prospects using geologic risk factors. Oil accumulations in these basins are in strata deposited during Cretaceous rift and drift phases, thus providing a diversity of geologic settings to examine. Oil accumulations in rift deposits are located on large faulted anticlines or in truncated units atop horst features. Many of these oil fields were sourced from adjacent organic shales along short direct migration paths. In Areas where source rock is more remote to fields or to prospective structures, faulting and continuity of reservoir rock are important to the migration of hydrocarbons. Because Aptian salts separate rift-related deposits from those of the drift stage, salt evacuation and faulting of the salt residuum are necessary for oil migration from the pre-salt sequences into the post-salt section. Oil migration within post-salt strata is complicated by the presence of salt walls and faulted carbonate platforms. Hydrocarbon shows in wells drilled throughout this area provide critical data for evaluating hydrocarbon migration pathways. Such evaluation in combination with modeling and mapping of the organic-rich units, maturation, reservoir facies, structural configurations, and seals in existing fields allows assessment of different plays. Based on this information, new play types and prospective structures can be ranked with respect to geologic risk.

  9. Triad thiophosphoryl-mercapto ylide tautomerism. III. Synthesis and structure of (1-(diphenylphosphinothioyl)-acetonyl)triphenylphosphonium salts

    SciTech Connect

    Aladzheva, I.M.; Leont'eva, I.V.; Petrovskii, P.V.; Mastryukova, T.A.; Kabachnik, M.I.

    1986-11-20

    (1-(Diphenylphosphinothioyl)acetonylidene)triphenylphosphorane was synthesized, and in its protonation phosphonium salts are formed which have an enol structure in the solid state, but exist as an equilibrium mixture of keto and enol forms in solution. The methylation of the phosphorane goes at the oxygen atom of the carbonyl group and at the sulfur atom the thiophosphoryl group, and the S-methylation product undergoes intramolecular Wittig reaction under mild conditions. Hydrogen 1 and phosphorus 31 NMR spectra were analyzed to confirm these findings.

  10. Divisions of potential fracture permeability, based on distribution of structures and linear features in sedimentary rocks, northern Great Plains-Rocky Mountains region of Montana, North Dakota, South Dakota, Wyoming, and northern Nebraska

    USGS Publications Warehouse

    Cooley, Maurice E.

    1986-01-01

    Division of fracture traces in sedimentary rocks of Cenozoic to Precambrian Age - Eastern and central North and South Dakota and northern Nebraska include only Cenozoic to Pennsylvanian rocks at the surface and at relatively shallow depths; the area of shallow thrust faulting in north-central Montana includes many Cretaceous rocks. Fractures in the deeper rocks in these areas vary, depending on the local structure. Large areas of western Montana are underlain by Precambrian sedimentary rocks

  11. Linear geologic structure and magic rock discrimination as determined from infrared data

    NASA Technical Reports Server (NTRS)

    Offield, T. W.; Rowan, L. C.; Watson, R. D.

    1970-01-01

    Color infrared photographs of the Beartooth Mountains, Montana show the distribution of mafic dikes and amphibolite bodies. Lineaments that cross grassy plateaus can be identified as dikes by the marked constrast between the dark rocks and the red vegetation. Some amphibolite bodies in granitic terrain can also be detected by infrared photography and their contacts can be accurately drawn due to enchanced contrast of the two types of rock in the near infrared. Reflectance measurements made in the field for amphibolite and granite show that the granite is 25% to 50% more reflective in the near infrared than in the visible region. Further enhancement is due to less atmospheric scattering than in the visible region. Thermal infrared images of the Mill Creek, Oklahoma test site provided information on geologic faults and fracture systems not obtainable from photographs. Subtle stripes that cross outcrop and intervening soil areas and which probably record water distribution are also shown on infrared photographs.

  12. IIb trioctahedral chlorite from the Barberton greenstone belt: crystal structure and rock composition constraints with implications to geothermometry

    NASA Astrophysics Data System (ADS)

    Xie, Xiaogang; Byerly, Gary R.; Ferrell, Ray E., Jr.

    IIb trioctahedral chlorite in the Barberton greenstone belt (BGB) metavolcanic rocks was formed during pervasive greenschist metamorphism. The chem-ical composition of the chlorite is highly variable, with the Fe/(Fe+Mg) ratio ranging from 0.12 to 0.8 among 53 samples. The chemical variation of the chlorite results from the chemical diversity of the host rock, especially the MgO content of the rock, but major details of the variation pattern of the chlorite are due to the crystal structure of the chlorite. All major cation abundances in the chlorite are strongly correlated with each other. Sil-icon increases with Mg and decreases with Fe, while AlIV and AlVI decrease with Mg and increase with Fe2+. A complex exchange vector explains over 90% of the chlorite compositional variation: Mg4SiFe2+-3AlVI-1 AlIV-1, which has 3 parts Fe-Mg substitution coupled with one part tschermakite substitution. This ratio is required to maintain the charge and site balances and the dimensional fit between the tetrahedral and octahedral sheets. The subtle change in Al substitution in chlorite implies that AlVI is preferentially ordered in the M(4) site, and about 84% of the AlVI present is in the M(4) sites when they are nearly filled with AlVI. Based on 47 analyzed chlorite-bearing rock samples, chlorite (Chl) composition is strongly correlated with the MgO content of the host rock. Calculated correlation coefficients are +0.91 for SiO2Chl-MgORock, -0.87 for Al2O3Chl-MgORock, +0.89 for MgOChl-MgORock, and -0.85 for FeOChl-MgORock. Only weak correlations have been found between chlorite oxides and other oxides of rock (between same oxides in chlorite and rock: SiO2-0.67, Al2O3+0.59, FeO -0.41). However, MgOChl is saturated at about 36 wt% in rocks that have MgO above 22 wt%.The MgOChl is about 5 wt% when the host rock approaches 0 wt% of MgO. This implies that Mg substituting into the chlorite is approximately limited to 1.5-9.2 Mg atoms per formula unit and 1.0-3.2 AlIV. Chlorite

  13. Structural analysis of the unstable rock slope area at Stampa above Flåm, Norway

    NASA Astrophysics Data System (ADS)

    Böhme, Martina; Hermanns, Reginald L.; Tukkensæter, Áse; Derron, Marc-Henri; Eiken, Trond; Carrea, Dario; Jaboyedoff, Michel

    2010-05-01

    The unstable rock slope area around Stampa in Flåmsdalen is one of the largest actively deforming rockslide areas in Western Norway (Domaas et al., 2002). It covers an area of up to 11 km² that extends 7 km N-S and 2 km W-E and shows signs of active and postglacial gravitational deformation. As the consequence of a failure could be high, an intensive investigation program was requested. Part of this are detailed structural field mapping, a differential GPS survey, as well as the generation of a detailed topographic model based on airborne laser scanning (ALS) data and several terrestrial laser scanning (TLS) surveys. The structural analysis of the three different sources of structural data (ALS, TLS and field measurements) revealed 3 main joint sets with the following mean orientations: (J1) 078/83, (J2) 021/89 and (J3) 116/82. These joint sets are very constant in orientation and appearance over the whole unstable area. Several open fractures (up to 300 m long and 10 m wide), which are visible on the DEM and in the field, developed along those main sets or a combination of two of them. The foliation is strongly folded with varying types of folding, ranging from cm-scale crenulation folds to larger amplitude (meter-scale) open folds, but with a constant horizontal fold axis. Despite this complex folding pattern, the foliation develops preferentially planes dipping shallowly to moderately towards the fjord. There is a change in mean foliation observed, which let together with major structures and observed deformation patterns, to a subdivision of different parts of the unstable area that seem to deform independently and show different stages of deformation. The northern part of the unstable area shows the most advanced stage of deformation. In this region are the biggest open fractures located, which developed along J1 and J3, as well as two nearly freestanding blocks with the highest measured movement rates. J3 and J1 define back and lateral scarp of this two

  14. Talking Rocks.

    ERIC Educational Resources Information Center

    Rice, Dale; Corley, Brenda

    1987-01-01

    Discusses some of the ways that rocks can be used to enhance children's creativity and their interest in science. Suggests the creation of a dramatic production involving rocks. Includes basic information on sedimentary, igneous, and metamorphic rocks. (TW)

  15. Stratigraphic and structural relations of Lower Triassic rocks within the frontal fold-and-thrust zone of southwestern Montana

    SciTech Connect

    Paull, R.K.; Paull, R.A. )

    1991-06-01

    New sections of Lower Triassic rocks were measured within the frontal fold-and-thrust zone of southwestern Montana at Garfield Canyon, Horse Prairie Creek, Kennison Spring, and Birch Creek to clarify stratigraphic and structural relations. Triassic rocks disconformably overlie Upper Permian units and unconformably underlie younger rocks. From oldest to youngest, they include the Dinwoody, Woodside, and Thaynes formations. The Dinwoody consists of shale, siltstone, and limestone; thickness varies from 152 to 273 m. Red beds of the Woodside thin northward to zero in the northern Tendoy Mountains. The Thaynes is comprised of limestone, siltstone, and sandstone; thickness varies from 244 m in the south, zero in the central area, to 51 m in the north. North of the Woodside termination, recognition of the Thaynes depends upon recovery of Smithian conodonts. Conodonts provide correlation and biofacies information for this study. From Birch Creek northward, conodonts are basinal, consistent with lithofacies data. This area is within the McCartney Mountain salient, a depositional basin which may have existed on the craton margin prior to thrusting. However, there is no evidence to support basinal conditions in the Blacktail Mountain salient to the south. Although thermal alteration values for most conodonts are within the range of oil and condensate production, those from Birch Creek north exceed the stability regime for hydrocarbons.

  16. Evolution of crystalline target rocks and impactites in the chesapeake bay impact structure, ICDP-USGS eyreville B core

    USGS Publications Warehouse

    Horton, J.W., Jr.; Kunk, M.J.; Belkin, H.E.; Aleinikoff, J.N.; Jackson, J.C.; Chou, I.-Ming

    2009-01-01

    The 1766-m-deep Eyreville B core from the late Eocene Chesapeake Bay impact structure includes, in ascending order, a lower basement-derived section of schist and pegmatitic granite with impact breccia dikes, polymict impact breccias, and cataclas tic gneiss blocks overlain by suevites and clast-rich impact melt rocks, sand with an amphibolite block and lithic boulders, and a 275-m-thick granite slab overlain by crater-fill sediments and postimpact strata. Graphite-rich cataclasite marks a detachment fault atop the lower basement-derived section. Overlying impactites consist mainly of basement-derived clasts and impact melt particles, and coastalplain sediment clasts are underrepresented. Shocked quartz is common, and coesite and reidite are confirmed by Raman spectra. Silicate glasses have textures indicating immiscible melts at quench, and they are partly altered to smectite. Chrome spinel, baddeleyite, and corundum in silicate glass indicate high-temperature crystallization under silica undersaturation. Clast-rich impact melt rocks contain ??- cristobalite and monoclinic tridymite. The impactites record an upward transition from slumped ground surge to melt-rich fallback from the ejecta plume. Basement-derived rocks include amphibolite-facies schists, greenschist(?)-facies quartz-feldspar gneiss blocks and subgreenschist-facies shale and siltstone clasts in polymict impact breccias, the amphibolite block, and the granite slab. The granite slab, underlying sand, and amphibolite block represent rock avalanches from inward collapse of unshocked bedrock around the transient crater rim. Gneissic and massive granites in the slab yield U-Pb sensitive high-resolution ion microprobe (SHRIMP) zircon dates of 615 ?? 7 Ma and 254 ?? 3 Ma, respectively. Postimpact heating was 7lt;~350 ??C in the lower basementderived section based on undisturbed 40Ar/ 39Ar plateau ages of muscovite and <~150

  17. Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts

    NASA Astrophysics Data System (ADS)

    Sing, M.; Schwingenschlögl, U.; Claessen, R.; Dressel, M.; Jacobsen, C. S.

    2003-03-01

    We have thoroughly characterized the surfaces of the organic charge-transfer salts TTF-TCNQ and (TMTSF)2PF6 which are generally acknowledged as prototypical examples of one-dimensional conductors. In particular x-ray-induced photoemission spectroscopy turns out to be a valuable nondestructive diagnostic tool. We show that the observation of generic one-dimensional signatures in photoemission spectra of the valence band close to the Fermi level can be strongly affected by surface effects. Especially, great care must be exercised taking evidence for an unusual one-dimensional many-body state exclusively from the observation of a pseudogap.

  18. Synthesis of a new quaternary phosphonium salt: NMR study of the conformational structure and dynamics.

    PubMed

    Aganova, Oksana V; Galiullina, Leysan F; Aganov, Albert V; Shtyrlin, Nikita V; Pugachev, Mikhail V; Strel'nik, Alexey D; Koshkin, Sergey A; Shtyrlin, Yurii G; Klochkov, Vladimir V

    2016-04-01

    A novel phosphonium salt based on pyridoxine was synthesized. Conformational analysis of the compound in solution was performed using dynamic NMR experiments and calculations. The obtained results revealed some differences in the conformational transitions and the energy parameters of the conformational exchange of the studied compound in comparison to previously reported data for other phosphorus-containing pyridoxine derivatives. It was shown that increasing the substituent at the C-11 carbon leads to greater differences in the populations of stable states and the corresponding equilibrium energies. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26661926

  19. Rock elastic properties and near-surface structure at Taurus-Littrow. [strain measurement of lunar basalt and breccia

    NASA Technical Reports Server (NTRS)

    Trice, R.; Warren, N.; Anderson, O. L.

    1974-01-01

    Linear strain measurements are presented for two lunar basalts, 14310,82 and 71055,15 and one breccia, 15498,23 to 5 kb hydrostatic pressure. Compressional and shear acoustic velocities to 5 kb are also presented for the basalts, 14310,82 and 71055,15. These elastic properties, along with geological, seismological and rock mechanics considerations are consistent with a model of the structure of the Taurus-Littrow valley as follows, a thin surface regolith overlying a fractured mixture of basalt flows and ejecta material which in turn overlies a coherent breccia of highland ejecta debris.

  20. Structural insights into the adaptation of proliferating cell nuclear antigen (PCNA) from Haloferax volcanii to a high-salt environment

    SciTech Connect

    Morgunova, Ekaterina; Gray, Fiona C.; MacNeill, Stuart A.; Ladenstein, Rudolf

    2009-10-01

    The crystal structure of PCNA from the halophilic archaeon H. volcanii reveals specific features of the charge distribution on the protein surface that reflect adaptation to a high-salt environment and suggests a different type of interaction with DNA in halophilic PCNAs. The sliding clamp proliferating cell nuclear antigen (PCNA) plays vital roles in many aspects of DNA replication and repair in eukaryotic cells and in archaea. Realising the full potential of archaea as a model for PCNA function requires a combination of biochemical and genetic approaches. In order to provide a platform for subsequent reverse genetic analysis, PCNA from the halophilic archaeon Haloferax volcanii was subjected to crystallographic analysis. The gene was cloned and expressed in Escherichia coli and the protein was purified by affinity chromatography and crystallized by the vapour-diffusion technique. The structure was determined by molecular replacement and refined at 3.5 Å resolution to a final R factor of 23.7% (R{sub free} = 25%). PCNA from H. volcanii was found to be homotrimeric and to resemble other homotrimeric PCNA clamps but with several differences that appear to be associated with adaptation of the protein to the high intracellular salt concentrations found in H. volcanii cells.

  1. An approach to better understanding of salt weathering on stone monuments - the "petraSalt" research project

    NASA Astrophysics Data System (ADS)

    Heinrichs, K.; Azzam, R.

    2012-04-01

    Salt weathering is known as a major cause of damage on stone monuments. However, processes and mechanisms of salt weathering still can not be explained satisfactorily. From the expertś point of view, better understanding of salt weathering deserves further comprehensive in-situ investigation jointly addressing active salt weathering processes and controlling factors. The 'petraSalt' research project takes this approach. The rock-cut monuments of Petra / Jordan were selected for studies, since stone type and spectra of monument exposure regimes, environmental influences, salt loading and weathering damage are representative for many stone monuments worldwide. The project aims at real-time / real-scale weathering models that depict characteristic interdependencies between stone properties, monument exposure regimes, environmental influences, salt loading and salt weathering damage. These models are expected to allow reliable rating and interpretation of aggressiveness and damage potential of the salt weathering regimes considering their variability under range of lithology, monument exposure scenarios, environmental conditions and time. The methodological approach systematically combines assessment of weathering damage (type, extent, spatial distribution and progression of damage), assessment of monument exposure characteristics and environmental influences acting on the monuments (monument orientation / geometry, lithology, rain impact, water run-off, rising humidity, wind impact, insolation, heating-cooling and drying-wetting behaviour, etc.), engineering geological studies (structural discontinuities and related failure processes) and investigation of salt loading (type, concentration, spatial distribution and origin of salt, salt crystallization / dissolution, phase transitions, etc.). Besides established methods, very innovative technologies are applied in the course of investigation such as high-resolution 3D terrestrial laser scanning (TLS) and wireless

  2. Geologic characterization report for the Paradox Basin Study Region, Utah Study Areas. Volume 6. Salt Valley

    SciTech Connect

    Not Available

    1984-12-01

    Surface landforms in the Salt Valley Area are generally a function of the Salt Valley anticline and are characterized by parallel and subparallel cuestaform ridges and hogbacks and flat valley floors. The most prominent structure in the Area is the Salt Valley anticline. Erosion resulting from the Tertiary uplift of the Colorado Plateau led to salt dissolution and subsequent collapse along the crest of the anticline. Continued erosion removed the collapse material, forming an axial valley along the crest of the anticline. Paleozoic rocks beneath the salt bearing Paradox Formation consist of limestone, dolomite, sandstone, siltstone and shale. The salt beds of the Paradox Formation occur in distinct cycles separated by an interbed sequence of anhydrite, carbonate, and clastic rocks. The Paradox Formation is overlain by Pennsylvanian limestone; Permian sandstone; and Mesozoic sandstone, mudstone, conglomerate and shale. No earthquakes have been reported in the Area during the period of the historic record and contemporary seismicity appears to be diffusely distributed, of low level and small magnitude. The upper unit includes the Permian strata and upper Honaker Trail Formation. The current data base is insufficient to estimate ground-water flow rates and directions in this unit. The middle unit includes the evaporites in the Paradox Formation and no laterally extensive flow systems are apparent. The lower unit consists of the rocks below the Paradox Formation where permeabilities vary widely, and the apparent flow direction is toward the west. 108 refs., 39 figs., 9 tabs.

  3. Measuring lifting forces in rock climbing: effect of hold size and fingertip structure.

    PubMed

    Bourne, Roger; Halaki, Mark; Vanwanseele, Benedicte; Clarke, Jillian

    2011-02-01

    This study investigates the hypothesis that shallow edge lifting force in high-level rock climbers is more strongly related to fingertip soft tissue anatomy than to absolute strength or strength to body mass ratio. Fifteen experienced climbers performed repeated maximal single hand lifting exercises on rectangular sandstone edges of depth 2.8, 4.3, 5.8, 7.3, and 12.5 mm while standing on a force measurement platform. Fingertip soft tissue dimensions were assessed by ultrasound imaging. Shallow edge (2.8 and 4.3 mm) lifting force, in newtons or body mass normalized, was uncorrelated with deep edge (12.5 mm) lifting force (r < .1). There was a positive correlation (r = .65, p < .05) between lifting force in newtons at 2.8 mm edge depth and tip of bone to tip of finger pulp measurement (r < .37 at other edge depths). The results confirm the common perception that maximum lifting force on a deep edge ("strength") does not predict maximum force production on very shallow edges. It is suggested that increased fingertip pulp dimension or plasticity may enable increased deformation of the fingertip, increasing the skin to rock contact area on very shallow edges, and thus increase the limit of force production. The study also confirmed previous assumptions of left/right force symmetry in climbers. PMID:21451181

  4. Structural controls on source rock distribution and maturation in southeast Turkey

    SciTech Connect

    Reed, J.D.; Ottensman, V.V.; Cushing, G.W. ); Aytuna, S. )

    1990-05-01

    Production from the western part of the Zagros fold and thrust belt southeastern Turkey is characterized by high-sulfur (2-3%) oils from middle Cretaceous Mardin Formation. The oils are generated from two carbonate sources, one from the middle Cretaceous passive margin sequence and one deposited as a part of the Upper Cretaceous foreland basin sequence. Both sources are associated with transgressive events coincident with two recognized Cretaceous oceanic anoxic events in Cenomanian-Turonian and Coniacian-Santonian. Geochemical markers in the oils substantiate the restricted, anoxic conditions characteristic of their source rock deposition. During the Upper Cretaceous compressional event, horsts formed buttresses to advancing oceanic thrust sheets. The oceanic thrust sheets consisted of the Karadut and Kocali formations, oceanic equivalents of the Mesozoic shelf. The middle and Upper Cretaceous source facies were rapidly and deeply buried by the tectonically thickened thrust sheets adjacent to the buttresses. Thick burial by the oceanic rocks was critical for thermal maturation of the sources. Geohistory modeling shows generation occurred during the Tertiary coincidental with tectonic activity that probably allowed oil migration to occur along new or reactivated Cretaceous faults.

  5. Hydrogen bonding in the crystal structure of the molecular salt of pyrazole–pyrazolium picrate

    PubMed Central

    Su, Ping; Song, Xue-gang; Sun, Ren-qiang; Xu, Xing-man

    2016-01-01

    The asymmetric unit of the title organic salt [systematic name: 1H-pyrazol-2-ium 2,4,6-tri­nitro­phenolate–1H-pyrazole (1/1)], H(C3H4N2)2 +·C6H2N3O7 −, consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N—H⋯N hydrogen bond is disordered over both symmetry-unique pyrazole mol­ecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N—H⋯(O,O) hydrogen bonds. In addition, weak C—H⋯O hydrogen bonds link inversion-related chains, forming columns along [100]. PMID:27308060

  6. Lithium salt of end-substituted nanotube: Structure and large nonlinear optical property

    NASA Astrophysics Data System (ADS)

    Ma, Fang; Zhou, Zhong-Jun; Li, Zhi-Ru; Wu, Di; Li, Ying; Li, Ze-Sheng

    2010-03-01

    Lithium salt of substituted nanotube is suggested as a new kind of nonlinear optical (NLO) material. It is found that the combination of the lithiation effect and the donor substitution effect can greatly enhance the static first hyperpolarizability ( β0). Specially, the unusual donor - acceptor(nanotube) - donor system Li-NT(6,0)-(NH 2) 2 has considerable β0 to be 6.8 × 10 5 au, due to its small transition energy and large transition moment. Further, the relationships between β0 and the number of Li atoms m and the substituents R for Li m-NT(6,0)-( R) 2 ( m = 1, 6 and R = -CN, -NH 2) systems are explored.

  7. Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

    NASA Astrophysics Data System (ADS)

    de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

    2006-12-01

    HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

  8. Deformation of Sedimentary Rock Across the San Andreas Fault Zone: Mesoscale and Microscale Structures Displayed in Core From SAFOD

    NASA Astrophysics Data System (ADS)

    Chester, J. S.; Chester, F. M.; Kirschner, D. L.; Almeida, R.; Evans, J. P.; Guillemette, R. N.; Hickman, S.; Zoback, M.; Ellsworth, W.

    2007-12-01

    Sedimentary rocks captured in cores taken at the San Andreas Fault Observatory at Depth (SAFOD) provide an unparalleled sampling of deformation in the transition zone between creeping and locked segments of a major transform fault at 2.5-3.1 km vertical depth. These samples provide the unique opportunity to study deformation processes and the development of brittle structures within porous and granular rocks that have been subjected to variable loading rates and chemically reactive fluids while residing at the top of the seismogenic zone. The samples provide a transect from relatively undeformed host rock through highly fractured and sheared rock, and capture the two prominent zones of active, aseismic slip. Core recovery was almost complete. Wrap-around 1:1 map tracings of the outer surfaces of all cores characterize the lithology and mesoscale deformation. Cores from 3056-3067 m and 3141-3153 m measured depth (MD) sample moderately deformed rock at the western boundary of the fault zone. The cores display massive to finely laminated, pebbly arkosic sandstones with lesser amounts of fine-grained sandstone and siltstone. Numerous shear fractures and cm-thick cataclastic shear zones form a conjugate geometry indicating contraction at high angles to the San Andreas fault. Both intervals display minor faults that juxtapose different lithologies consistent with meters or greater of slip. Fracture density is variable but tends to increase with proximity to the minor faults. Cross-cutting relationships between shear fractures and cataclastic zones indicate a general progression from early faulting along thicker shear zones to later, more localized slip within shear zones and along fractures. Microstructures provide ample evidence for densification of the sandstones through grain-scale fracture and crushing, as well as fluid assisted processes of crack-sealing, dissolution-precipitation, and alteration-neocrystallization. Grain-scale features are consistent with these

  9. Rock mechanics for hard rock nuclear waste repositories

    SciTech Connect

    Heuze, F.E.

    1981-09-01

    The mined geologic burial of high level nuclear waste is now the favored option for disposal. The US National Waste Terminal Storage Program designed to achieve this disposal includes an extensive rock mechanics component related to the design of the wastes repositories. The plan currently considers five candidate rock types. This paper deals with the three hard rocks among them: basalt, granite, and tuff. Their behavior is governed by geological discontinuities. Salt and shale, which exhibit behavior closer to that of a continuum, are not considered here. This paper discusses both the generic rock mechanics R and D, which are required for repository design, as well as examples of projects related to hard rock waste storage. The examples include programs in basalt (Hanford/Washington), in granitic rocks (Climax/Nevada Test Site, Idaho Springs/Colorado, Pinawa/Canada, Oracle/Arizona, and Stripa/Sweden), and in tuff (Nevada Test Site).

  10. The solution structure of the four-way DNA junction at low-salt conditions: a fluorescence resonance energy transfer analysis.

    PubMed Central

    Clegg, R M; Murchie, A I; Lilley, D M

    1994-01-01

    The four-way DNA (Holliday) junction is an important postulated intermediate in the process of genetic recombination. Earlier studies have suggested that the junction exists in two alternative conformations, depending upon the salt concentration present. At high salt concentrations the junction folds into a stacked X structure, while at low salt concentrations the data indicate an extended unstacked conformation. The stereochemical conformation of the four-way DNA junction at low salt (low alkali ion concentration and no alkaline earth ions) was established by comparing the efficiency of fluorescence resonance energy transfer (FRET) between donor and acceptor molecules attached pairwise in three permutations to the 5' termini of the duplex arms. A new variation of FRET was implemented based upon a systematic variation of the fraction of donor labeled single strands. The FRET results indicate that the structure of the four-way DNA junction at low salt exists as an unstacked, extended, square arrangement of the four duplex arms. The donor titration measurements made in the presence of magnesium ions clearly show the folding of the junction into the X stacked structure. In addition, the FRET efficiency can be measured. The fluorescence anisotropy of the acceptor in the presence of Mg2+ during donor titrations was also measured; the FRET efficiency can be calculated from the anisotropy data and the results are consistent with the folded, stacked X structure. PMID:8130350

  11. Use of complementary cation and anion heavy-atom salt derivatives to solve the structure of cytochrome P450 46A1

    SciTech Connect

    White, Mark Andrew; Mast, Natalia; Bjorkhem, Ingemar; Johnson, Eric F.; Stout, C. David; Pikuleva, Irina A.

    2008-05-01

    Crystallization and analysis of the MIRAS heavy-atom structure solution of human cytochrome P450 46A1 using NaI and CsCl quick soaks. Human cytochrome P450 46A1 (CYP46A1) is one of the key enzymes in cholesterol homeostasis in the brain. The crystallization and heavy-atom structure solution of an active truncated CYP46A1 in complex with the high-affinity substrate analogue cholesterol-3-sulfate (CH-3S) is reported. The 2.6 Å structure of CYP46A1–CH-3S was solved using both anion and cation heavy-atom salts. In addition to the native anomalous signal from the haem iron, an NaI anion halide salt derivative and a complementary CsCl alkali-metal cation salt derivative were used. The general implications of the use of halide and alkali-metal quick soaks are discussed. The importance of using isoionic strength buffers, the titration of heavy-atom salts into different ionic species and the role of concentration are considered. It was observed that cation/anion-binding sites will occasionally overlap, which could negatively impact upon mixed RbBr soaks used for multiple anomalous scatterer MAD (MMAD). The use of complementary cation and anion heavy-atom salt derivatives is a convenient and powerful tool for MIR(AS) structure solution.

  12. Preparation of the sodium salt of high acyl gellan and characterization of its structure, thermal and rheological behaviors.

    PubMed

    Murillo-Martínez, María M; Tecante, Alberto

    2014-08-01

    This work presents a method to obtain the sodium salt of high acyl gellan (NaHAG) from a commercial preparation, LT-100, by ionic exchange and freeze drying without involving alcohol precipitation to recover the modified macromolecule. NaHAG was characterized by atomic absorption spectrophotometry, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction and proton nuclear magnetic resonance. In addition, gel viscoelasticity, sol-gel transition temperatures from rheological temperature sweeps and differential scanning calorimetry, of both preparations was examined. Up to 87% of the initial weight of LT-100 was recovered as NaHAG. The sodium ion content in NaHAG was 3.2 times greater than in LT-100 and more than 90% of potassium, calcium and magnesium ions present in the original sample were removed. Transition temperatures of LT-100 were significantly higher than those of NaHAG. However, LT-100 gels were slightly stronger and elastic than NaHAG gels. Characterization data from different analyses suggest that the treatment method makes possible to obtain NaHAG with only slight structure modification with respect to LT-100, and could be advantageously utilized to obtain other monovalent and divalent salt forms of high acyl gellan for use in fundamental studies on its properties in aqueous environment. PMID:24751279

  13. Crystal structure of a major fragment of the salt-tolerant glutaminase from Micrococcus luteus K-3

    SciTech Connect

    Yoshimune, Kazuaki . E-mail: k.yoshimune@aist.go.jp; Shirakihara, Yasuo; Shiratori, Aya; Wakayama, Mamoru; Chantawannakul, Panuwan; Moriguchi, Mitsuaki

    2006-08-11

    Glutaminase of Micrococcus luteus K-3 (intact glutaminase; 48 kDa) is digested to a C-terminally truncated fragment (glutaminase fragment; 42 kDa) that shows higher salt tolerance than that of the intact glutaminase. The crystal structure of the glutaminase fragment was determined at 2.4 A resolution using multiple-wavelength anomalous dispersion (MAD). The glutaminase fragment is composed of N-terminal and C-terminal domains, and a putative catalytic serine-lysine dyad (S64 and K67) is located in a cleft of the N-terminal domain. Mutations of the S64 or K67 residues abolished the enzyme activity. The N-terminal domain has abundant glutamic acid residues on its surface, which may explain its salt-tolerant mechanism. A diffraction analysis of the intact glutaminase crystals (a twinning fraction of 0.43) located the glutaminase fragment in the unit cell but failed to turn up clear densities for the missing C-terminal portion of the molecule.

  14. Effects of temperature and salt concentration on the structural and dynamical features in aqueous solutions of charged triblock copolymers.

    PubMed

    Kjøniksen, Anna-Lena; Zhu, Kaizheng; Behrens, Manja A; Pedersen, Jan Skov; Nyström, Bo

    2011-03-17

    Effects of temperature and salt addition on the association behavior in aqueous solutions of a series of charged thermosensitive methoxypoly(ethylene glycol)-block-poly(N-isopropylacrylamide)-block-poly(4-styrenesulfonic acid sodium) triblock copolymers (MPEG(45)-b-P(NIPAAM)(n)-b-P(SSS)(22)) with different lengths of the PNIPAAM block (n=17, 48, and 66) have been studied with the aid of turbidity, small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS). Increasing temperature and salinity as well as longer PNIPAAM blocks are all factors that promote the formation of association structures. The SAXS data show that, for the copolymers with n=48 and n=66, increasing temperature and salt concentration induce interchain associations and higher values of the aggregation number, whereas no aggregation was observed for the copolymer with the shortest PNIPAAM chain. However, DLS measurements reveal the presence of larger association clusters. The cloud point is found to decrease with raising salinity and longer PNIPAAM block. The general picture that emerges is the delicate interplay between repulsive electrostatic forces and hydrophobic interactions and that this balance can be tuned by changing the temperature, salinity, and the length of the PNIPAAM block. PMID:21338148

  15. Biostratigraphy and structure of paleozoic host rocks and their relationship to Carlin-type gold deposits in the Jerritt Canyon mining district, Nevada

    USGS Publications Warehouse

    Peters, S.G.; Armstrong, A.K.; Harris, A.G.; Oscarson, R.L.; Noble, P.J.

    2003-01-01

    The Jerritt Canyon mining district in the northern Independence Range, northern Nevada, contains multiple, nearly horizontal, thrust masses of platform carbonate rocks that are exposed in a series of north- to northeast-elongated, tectonic windows through rocks of the Roberts Mountains allochthon. The Roberts Mountains allochthon was emplaced during the Late Devonian to Early Mississippian Antler orogeny. These thrust masses contain structurally and stratigraphically controlled Carlin-type gold deposits. The gold deposits are hosted in tectonically truncated units of the Silurian to Devonian Hanson Creek and Roberts Mountains Formations that lie within structural slices of an Eastern assemblage of Cambrian to Devonian carbonate rocks. In addition, these multiply thrust-faulted and folded host rocks are structurally interleaved with Mississippian siliciclastic rocks and are overlain structurally by Cambrian to Devonian siliciclastic units of the Roberts Mountains allochthon. All sedimentary rocks were involved in thrusting, high-angle faulting, and folding, and some of these events indicate substantial late Paleozoic and/or Mesozoic regional shortening. Early Pennsylvanian and late Eocene dikes also intrude the sedimentary rocks. These rocks all were uplifted into a northeast-trending range by subsequent late Cenozoic Basin and Range faulting. Eocene sedimentary and volcanic rocks flank part of the range. Pathways of hydrothermal fluid flow and locations of Carlin-type gold orebodies in the Jerritt Canyon mining district were controlled by structural and host-rock geometries within specific lithologies of the stacked thrust masses of Eastern assemblage rocks. The gold deposits are most common proximal to intersections of northeast-striking faults, northwest-striking dikes, and thrust planes that lie adjacent to permeable stratigraphic horizons. The host stratigraphic units include carbonate sequences that contained primary intercrystalline permeability, which

  16. Integrated Salt Studies

    NASA Astrophysics Data System (ADS)

    Urai, Janos L.; Kukla, Peter A.

    2015-04-01

    The growing importance of salt in the energy, subsurface storage, and chemical and food industries also increases the challenges with prediction of geometries, kinematics, stress and transport in salt. This requires an approach, which integrates a broader range of knowledge than is traditionally available in the different scientific and engineering disciplines. We aim to provide a starting point for a more integrated understanding of salt, by presenting an overview of the state of the art in a wide range of salt-related topics, from (i) the formation and metamorphism of evaporites, (ii) rheology and transport properties, (iii) salt tectonics and basin evolution, (iv) internal structure of evaporites, (v) fluid flow through salt, to (vi) salt engineering. With selected case studies we show how integration of these domains of knowledge can bring better predictions of (i) sediment architecture and reservoir distribution, (ii) internal structure of salt for optimized drilling and better cavern design, (iii) reliable long-term predictions of deformations and fluid flow in subsurface storage. A fully integrated workflow is based on geomechanical models, which include all laboratory and natural observations and links macro- and micro-scale studies. We present emerging concepts for (i) the initiation dynamics of halokinesis, (ii) the rheology and deformation of the evaporites by brittle and ductile processes, (iii) the coupling of processes in evaporites and the under- and overburden, and (iv) the impact of the layered evaporite rheology on the structural evolution.

  17. Petrology of the Crystalline Rocks Hosting the Santa Fe Impact Structure

    NASA Technical Reports Server (NTRS)

    Schrader, C. M.; Cohen, B. A.

    2010-01-01

    We collected samples from within the area of shatter cone occurrence and for approximately 8 kilometers (map distance) along the roadway. Our primary goal is to date the impact. Our secondary goal is to use the petrology and Ar systematics to provide further insight into size and scale of the impact. Our approach is to: Conduct a detailed petrology study to identify lithologies that share petrologic characteristics and tectonic histories but with differing degrees of shock. Obtain micro-cores of K-bearing minerals from multiple samples for Ar-40/Ar-39 analysis. Examine the Ar diffusion patterns for multiple minerals in multiple shocked and control samples. This will help us to better understand outcrop and regional scale relationships among rocks and their responses to the impact event.

  18. Structure of the Paleozoic rocks in the Tonkin Summit Quadrangle, Eureka County, Nevda

    NASA Astrophysics Data System (ADS)

    Arney, Eric

    Paleozoic rocks in the northern Simpson Park Range, Tonkin Summit Quadrangle, are comprised of the syn-orogenic Roberts Mountains allochthon, the postorogenic Permian Garden Valley Formation, and autochthonous Devonian carbonates. Complex deformation includes the Late Devonian-Early Mississippian, Antler Orogeny, post-Antler thrusting, and Cenozoic Basin and Range extension. The Roberts Mountains thrust caused eastward advancement of deep marine, mainly siliciclastic strata on top of the shelfal, mainly carbonate platform during the Antler Orogeny. This study shows that an east-vergent, post-Antler thrust, emplace the topographically higher carbonate outliers of the autochthon on top of the Roberts Mountains allochthon. These carbonate masses sit on top of the Henderson thrust in the Tonkin Summit Quadrangle and timing of this thrust is constrained to be post-Permian.

  19. Rock Properties and Internal Structure of the San Andreas Fault near ~ 3 km Depth in the SAFOD Borehole Based on Meso- to Micro-scale Analyses of Phase III whole rock core

    NASA Astrophysics Data System (ADS)

    Bradbury, K.; Evans, J. P.

    2010-12-01

    We examine the relationships between rock properties and structure within ~ 41 m of PHASE III whole-rock core collected from ~ 3 km depth along the SAF in the San Andreas Fault Observatory at Depth (SAFOD) borehole, near Parkfield, CA. Direct mesoscale observations of the core are integrated with detailed petrography and microstructural analyses coupled with X-Ray Diffraction and X-Ray Fluorescence techniques to document variations in composition, alteration, and structures that may be related to deformation and/or fluid-rock interactions. Across the low velocity zone (LVZ) defined by borehole geophysical data, lithologies are comprised of a heterogeneous sequence of fine-grained sandstones, siltstones, mudstones, and shales with block-in-matrix textures and pervasively foliated fabrics. More competent clasts within the block-in-matrix materials exhibit pinch-and-swell shaped structures with crosscutting veins that do not extend into the surrounding phyllosilicate-rich matrix. Narrow fault strands at 3192 and 3302 m bound the LVZ and correspond to sites of active casing deformation (aseismic creep). Here, the rock consists of ~ 2 m thick serpentinite-bearing phyllosilicate gouge with a pervasive penetrative scaly clay fabric and phacoidal-shaped clasts. Bounding these two active slip surfaces are highly sheared and comminuted ultrafine-grained black fault rocks with abundant calcite veins parallel and oblique to the foliation trend. Localized shear surfaces bound multi-layered zones of medium to ultra-fine grained cataclasite in the near-fault environment and record multiple generations of brittle deformation processes. Deformation at high-strain rates is suggested by the presence of crack-seal veins in clasts within the block-in-matrix materials, the presence of porphyroclasts, and the development of S-C fabrics in the phyllosilicate-rich gouge. Across the fault(s) and related damage zones, foliated fabrics alternating with discrete fractures suggest a mixed

  20. Environmental impact on construction limestone at humid regions with an emphasis on salt weathering, Al-hambra islamic archaeological site, Granada City, Spain: case study

    NASA Astrophysics Data System (ADS)

    Kamh, G. M. E.

    2007-08-01

    Al-hambra is an immense and valuable archaeological site in Spain built on Sabika hill with red brick and natural sandy limestone. It exhibits weathering features indicating salt weathering process. The main aim of this study is to examine weathering processes and intensity acting on Al-hambra. Rock petrography and mineralogical composition have been examined using thin sections, scanning electron microscope, X-ray diffraction and X-ray fluorescence; limits of rock’s physical parameters using ultrasonic waves and mercury porosimeter; rock salt content through hydrochemical analysis. Salts attacking this structure are mainly from wet deposition of air pollutants on the long term chemical alteration of rock’s carbonate content to its equivalent salts. The salts’ concentration limit within the examined rock samples is considerably low but it is effective on the long run through hydration of sulphate salts and/or crystallization of chloride salts. Rock texture type and its silica as well as clay content reduces its resistance to internal stresses by salts as well as wetting and drying cycles at such humid area. The recession in limits of physical parameters examined for deep seated and weathered limestone samples quantitatively reflects weathering intensity on Al-hambra.

  1. A comprehensive alanine-scanning mutagenesis study reveals roles for salt bridges in the structure and activity of Pseudomonas aeruginosa elastase.

    PubMed

    Bian, Fei; Yue, Shousong; Peng, Zhenying; Zhang, Xiaowei; Chen, Gao; Yu, Jinhui; Xuan, Ning; Bi, Yuping

    2015-01-01

    The relationship between salt bridges and stability/enzymatic activity is unclear. We studied this relationship by systematic alanine-scanning mutation analysis using the typical M4 family metalloprotease Pseudomonas aeruginosa elastase (PAE, also known as pseudolysin) as a model. Structural analysis revealed seven salt bridges in the PAE structure. We constructed ten mutants for six salt bridges. Among these mutants, six (Asp189Ala, Arg179Ala, Asp201Ala, Arg205Ala, Arg245Ala and Glu249Ala) were active and four (Asp168Ala, Arg198Ala, Arg253Ala, and Arg279Ala) were inactive. Five mutants were purified, and their catalytic efficiencies (kcat/Km), half-lives (t1/2) and thermal unfolding curves were compared with those of PAE. Mutants Asp189Ala and Arg179Ala both showed decreased thermal stabilities and increased activities, suggesting that the salt bridge Asp189-Arg179 stabilizes the protein at the expense of catalytic efficiency. In contrast, mutants Asp201Ala and Arg205Ala both showed slightly increased thermal stability and slightly decreased activity, suggesting that the salt bridge Asp201-Arg205 destabilizes the protein. Mutant Glu249Ala is related to a C-terminal salt bridge network and showed both decreased thermal stability and decreased activity. Furthermore, Glu249Ala showed a thermal unfolding curve with three discernable states [the native state (N), the partially unfolded state (I) and the unfolded state (U)]. In comparison, there were only two discernable states (N and U) in the thermal unfolding curve of PAE. These results suggest that Glu249 is important for catalytic efficiency, stability and unfolding cooperativity. This study represents a systematic mutational analyses of salt bridges in the model metalloprotease PAE and provides important insights into the structure-function relationship of enzymes. PMID:25815820

  2. Use of Complementary Cation And Anion Heavy Atom-Atom Salt Derivatives to Solve the Structure of Cytochrome P450 46a1

    SciTech Connect

    White, M.A.; Mast, N.; Bjorkhem, I.; Johnson, E.F.; Stout, C.D.; Pikuleva, I.A.

    2009-05-26

    Human cytochrome P450 46A1 (CYP46A1) is one of the key enzymes in cholesterol homeostasis in the brain. The crystallization and heavy-atom structure solution of an active truncated CYP46A1 in complex with the high-affinity substrate analogue cholesterol-3-sulfate (CH-3S) is reported. The 2.6 {angstrom} structure of CYP46A1-CH-3S was solved using both anion and cation heavy-atom salts. In addition to the native anomalous signal from the haem iron, an NaI anion halide salt derivative and a complementary CsCl alkali-metal cation salt derivative were used. The general implications of the use of halide and alkali-metal quick soaks are discussed. The importance of using isoionic strength buffers, the titration of heavy-atom salts into different ionic species and the role of concentration are considered. It was observed that cation/anion-binding sites will occasionally overlap, which could negatively impact upon mixed RbBr soaks used for multiple anomalous scatterer MAD (MMAD). The use of complementary cation and anion heavy-atom salt derivatives is a convenient and powerful tool for MIR(AS) structure solution.

  3. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    NASA Astrophysics Data System (ADS)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  4. Molecular structure and spectroscopic analysis of homovanillic acid and its sodium salt - NMR, FT-IR and DFT studies

    NASA Astrophysics Data System (ADS)

    Samsonowicz, M.; Kowczyk-Sadowy, M.; Regulska, E.; Lewandowski, W.

    2014-01-01

    The estimation of the electronic charge distribution in metal complex or salt allows to predict what kind of deformation of the electronic system of ligand would undergo during complexation. It also permits to make more precise interpretation of mechanism by which metals affect the biochemical properties of ligands. The influence of sodium cation on the electronic system of homovanillic acid was studied in this paper. Optimized geometrical structures of studied compounds were calculated by B3LYP/6-311++G** method. Mulliken, MK and ChelpG atomic charges were analyzed. The theoretical NMR and IR spectra were obtained. 1H and 13C NMR as well as FT-IR and FT-Raman spectra of studied compounds were also recorded and analyzed. The calculated parameters are compared with experimental characteristics of these molecules.

  5. Synthesis, Crystal Structure and Biological Activity of 2-Hydroxyethylammonium Salt of p-Aminobenzoic Acid

    PubMed Central

    Crisan, Manuela E.; Bourosh, Paulina; Maffei, Massimo E.; Forni, Alessandra; Pieraccini, Stefano; Sironi, Maurizio; Chumakov, Yurii M.

    2014-01-01

    p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surface area, docking experiments, Molecular Dynamics and Quantum Mechanics/Molecular Mechanics calculations. The docking study of the folate precursor pABA, its anionic form and natural auxin (indole-3-acetic acid, IAA) with the auxin receptor TIR1 revealed a similar binding mode in the active site. The phytotoxic evaluation of HEA-pABA, pABA and 2-hydroxyethylamine (HEA) was performed on the model plant Arabidopsis thaliana ecotype Col 0 at five different concentrations. HEA-pABA and pABA acted as potential auxin-like regulators of root development in Arabidopsis thaliana (0.1 and 0.2 mM) and displayed an agravitropic root response at high concentration (2 mM). This study suggests that HEA-pABA and pABA might be considered as potential new regulators of plant growth. PMID:25054237

  6. Synthesis, crystal structure and biological activity of 2-hydroxyethylammonium salt of p-aminobenzoic acid.

    PubMed

    Crisan, Manuela E; Bourosh, Paulina; Maffei, Massimo E; Forni, Alessandra; Pieraccini, Stefano; Sironi, Maurizio; Chumakov, Yurii M

    2014-01-01

    p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surface area, docking experiments, Molecular Dynamics and Quantum Mechanics/Molecular Mechanics calculations. The docking study of the folate precursor pABA, its anionic form and natural auxin (indole-3-acetic acid, IAA) with the auxin receptor TIR1 revealed a similar binding mode in the active site. The phytotoxic evaluation of HEA-pABA, pABA and 2-hydroxyethylamine (HEA) was performed on the model plant Arabidopsis thaliana ecotype Col 0 at five different concentrations. HEA-pABA and pABA acted as potential auxin-like regulators of root development in Arabidopsis thaliana (0.1 and 0.2 mM) and displayed an agravitropic root response at high concentration (2 mM). This study suggests that HEA-pABA and pABA might be considered as potential new regulators of plant growth. PMID:25054237

  7. Structure/processing relationships of highly ordered lead salt nanocrystal superlattices.

    PubMed

    Hanrath, Tobias; Choi, Joshua J; Smilgies, Detlef-M

    2009-10-27

    We investigated the influence of processing conditions, nanocrystal/substrate interactions and solvent evaporation rate on the ordering of strongly interacting nanocrystals by synergistically combining electron microscopy and synchrotron-based small-angle X-ray scattering analysis. Spin-cast PbSe nanocrystal films exhibited submicrometer-sized supracrystals with face-centered cubic symmetry and (001)(s) planes aligned parallel to the substrate. The ordering of drop-cast lead salt nanocrystal films was sensitive to the nature of the substrate and solvent evaporation dynamics. Nanocrystal films drop-cast on rough indium tin oxide substrates were polycrystalline with small grain size and low degree of orientation with respect to the substrate, whereas films drop-cast on flat Si substrates formed highly ordered face-centered cubic supracrystals with close-packed (111)(s) planes parallel to the substrate. The spatial coherence of nanocrystal films drop-cast in the presence of saturated solvent vapor was significantly improved compared to films drop-cast in a dry environment. Solvent vapor annealing was demonstrated as a postdeposition technique to modify the ordering of nanocrystals in the thin film. Octane vapor significantly improved the long-range order and degree of orientation of initially disordered or polycrystalline nanocrystal assemblies. Exposure to 1,2-ethanedithiol vapor caused partial displacement of surface bound oleic acid ligands and drastically degraded the degree of order in the nanocrystal assembly. PMID:19728701

  8. Maintenance of Chloroplast Structure and Function by Overexpression of the Rice MONOGALACTOSYLDIACYLGLYCEROL SYNTHASE Gene Leads to Enhanced Salt Tolerance in Tobacco1[W

    PubMed Central

    Wang, Shiwen; Uddin, M. Imtiaz; Tanaka, Kiyoshi; Yin, Lina; Shi, Zhonghui; Qi, Yanhua; Mano, Jun’ichi; Matsui, Kenji; Shimomura, Norihiro; Sakaki, Takeshi; Deng, Xiping; Zhang, Suiqi

    2014-01-01

    In plants, the galactolipids monogalactosyldiacylglycerol (MGDG) and digalactodiacylglycerol (DGDG) are major constituents of photosynthetic membranes in chloroplasts. One of the key enzymes for the biosynthesis of these galactolipids is MGDG synthase (MGD). To investigate the role of MGD in the plant’s response to salt stress, we cloned an MGD gene from rice (Oryza sativa) and generated tobacco (Nicotiana tabacum) plants overexpressing OsMGD. The MGD activity in OsMGD transgenic plants was confirmed to be higher than that in the wild-type tobacco cultivar SR1. Immunoblot analysis indicated that OsMGD was enriched in the outer envelope membrane of the tobacco chloroplast. Under salt stress, the transgenic plants exhibited rapid shoot growth and high photosynthetic rate as compared with the wild type. Transmission electron microscopy observation showed that the chloroplasts from salt-stressed transgenic plants had well-developed thylakoid membranes and properly stacked grana lamellae, whereas the chloroplasts from salt-stressed wild-type plants were fairly disorganized and had large membrane-free areas. Under salt stress, the transgenic plants also maintained higher chlorophyll levels. Lipid composition analysis showed that leaves of transgenic plants consistently contained significantly higher MGDG (including 18:3-16:3 and 18:3-18:3 species) and DGDG (including 18:3-16:3, 18:3-16:0, and 18:3-18:3 species) contents and higher DGDG-MGDG ratios than the wild type did under both control and salt stress conditions. These results show that overexpression of OsMGD improves salt tolerance in tobacco and that the galactolipids MGDG and DGDG play an important role in the regulation of chloroplast structure and function in the plant salt stress response. PMID:24843077

  9. Reservoir, seal, and source rock distribution in Essaouira Rift Basin

    SciTech Connect

    Ait Salem, A. )

    1994-07-01

    The Essaouira onshore basin is an important hydrocarbon generating basin, which is situated in western Morocco. There are seven oil and gas-with-condensate fields; six are from Jurassic reservoirs and one from a Triassic reservoir. As a segment of the Atlantic passive continental margin, the Essaouira basin was subjected to several post-Hercynian basin deformation phases, which resulted in distribution, in space and time, of reservoir, seal, and source rock. These basin deformations are synsedimentary infilling of major half grabens with continental red buds and evaporite associated with the rifting phase, emplacement of a thick postrifting Jurassic and Cretaceous sedimentary wedge during thermal subsidence, salt movements, and structural deformations in relation to the Atlas mergence. The widely extending lower Oxfordian shales are the only Jurassic shale beds penetrated and recognized as potential and mature source rocks. However, facies analysis and mapping suggested the presence of untested source rocks in Dogger marine shales and Triassic to Liassic lacustrine shales. Rocks with adequate reservoir characteristics were encountered in Triassic/Liassic fluvial sands, upper Liassic dolomites, and upper Oxfordian sandy dolomites. The seals are provided by Liassic salt for the lower reservoirs and Middle to Upper Jurassic anhydrite for the upper reservoirs. Recent exploration studies demonstrate that many prospective structure reserves remain untested.

  10. Synthesis, Crystal Structures and Physical Properties of TTF-Based Conducting Charge Transfer Salts with Anions Containing Selenocyanate Ligands

    NASA Astrophysics Data System (ADS)

    Turner, Scott S.; Le Pévelen, Delphine; Day, Peter; Prout, Keith

    2002-11-01

    Three new charge transfer salts of tetrathiafulvalene (TTF)-based donors with selenocyanate-metal complex anions have been synthesized. The salts have been characterized as BEDT-TTF 4[Cr(NCSe) 6]·CH 2Cl 2, II, TTF 3[Cr(NCSe) 4phen] 2, III and BEDT-TTF 2[Cr(NCSe) 4phen]·CH 2Cl 2, IV, where phen=1,10'-phenanthroline and BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene. At 120 K, II crystallizes in the P2 1/ m space group with a= 10.454(1), b= 31.990(1), c= 12.339(1) Å, β= 113.163(2)°, V= 3793.8Å 3, Z= 4 and at 240 K in the same space group with a= 10.530(1), b=32.122(1), c= 12.396(1) Å, β=113.186(3)°, V=3854.2 Å 3, Z=4. At 240 K III crystallizes in the C2/ c space group, a=38.9272(5), b=11.2992(1), c=15.2540(3) Å, β=106.8877(6)°, V=6420.1 Å 3, Z=8. The structure of IV has been solved in the Poverline1 space group with a=8.7629(3), b=11.7977(4), c=26.6031(9), α=81.697(2), β=87.858(3), γ=74.8471(14), V=2626.8 Å 3, Z=2. All of the salts have numerous S·Se close atomic contacts between donors and acceptors but there is no magnetic exchange between ions, as previously seen in closely related salts such as TTF[Cr(NCS) 4phen] and (donor)[ M(NCS) 4(isoquinoline) 2], where M=Cr, Fe and donor=TTF, BEDT-TTF or TMTTF (tetramethyltetrathiafulvalene). Indeed, II and IV are paramagnetic semiconductors whereas III is a paramagnetic insulator. The absence of long-range magnetic order is discussed in terms of structure-function relations since there are no π-stacking interactions between donor and acceptor, which are seen in all of the bulk magnets of this type where the donor spin is magnetically coupled to the anion. The synthesis and crystal structure of the starting material, [(C 4H 9) 4N] 3[Cr(NCSe) 6], I, is also reported; it crystallizes in the Poverline1 space group with a=12.220(1), b=12.814(1), c=13.008(1) Å, α=99.608(6), β=114.028(5), γ=92.637(6)°, V=1819.5 Å 3, Z=2.

  11. 3D gravity modeling of a salt structure associated to the Trozza-Labaied lineament (Central Tunisia) constrained by seismic and borehole data

    NASA Astrophysics Data System (ADS)

    Djebbi, M.; Gabtni, H.

    2015-03-01

    Gravity and seismic are two distinctive geophysical methods which are used combined in integrated geophysical studies. The rationale behind this integration is to construct a 3D gravity model for a salt structure associated to the Trozza-Labaied major tectonic deformation. The Trozza-Labaied area witnessed the occurrence of several tectonic events during the Atlassic phase resulting in the creation of various salt structures. Interpretation of the available seismic data revealed the different lithological units forming the geologic setting. Whereas the analysis of the gravity data contributed in exposing the existence of different gravity anomalies. Thus, the integrated seismic and gravity data are fundamental in constructing a 3D grav