Science.gov

Sample records for core concrete interaction

  1. Thermal-hydraulic studies on molten core-concrete interactions

    SciTech Connect

    Greene, G.A.

    1986-10-01

    This report discusses studies carried out in connection with light water power reactor accidents. Recent assessments have indicated that the consequences of molten-core concrete interactions dominate the considerations of severe accidents. The two areas of interest that have been investigated are interlayer heat and mass transfer and liquid-liquid boiling. Interlayer heat and mass transfer refers to processes that occur within a core melt between the stratified, immiscible phases of core oxides and metals. Liquid-liquid boiling refers to processes that occur at the melt-concrete on melt-coolant interface. (JDH)

  2. Core-concrete interactions using molten urania with zirconium on a limestone concrete basemat

    SciTech Connect

    Copus, E.R.; Brockmann, J.E.; Simpson, R.B.; Lucero, D.A. ); Blose, R.E. )

    1992-09-01

    An inductively heated experiment SURC-1, using UO[sub 2]-ZrO[sub 2] material, was executed to measure and assess the thermal, gas, and aerosol source terms produced during core debris/concrete interactions. The SURC-1 experiment eroded a total of 27 cm of limestone concrete during 130 minutes of sustained interaction using 204.2 kg of molten prototypic UO[sub 2]-ZrO[sub 2] core debris material that included 18 kg of zr metal and 3.4 kg of fission product simulants. The melt pool temperature ranged from 2100 to 2400[degrees]C during the first 50 minutes of the test, followed by steady temperatures of 2000 to 2100[degrees]C during the middle portion of the test and temperatures of 1800 to 2000[degrees]C during the final 50 minutes of testing. The total erosion during the first 50 minutes was 16 cm with an additional 2 cm during the middle part of the test and 9 cm of ablation during the final 50 minutes. Aerosols were continuously released in concentrations ranging from 30 to 200 g/m[sup 3]. Comprehensive gas flow rates, gas compositions, and aerosol compositions were also measured during the SURC-1 test.

  3. Modeling of anisotropic ablation of the concrete during Molten Core Concrete Interaction

    NASA Astrophysics Data System (ADS)

    Kang, Kyoung Min

    This work proposes a model to explain concrete anisotropic ablation by corium during a Molten Corium Concrete Interaction (MCCI). As a result of recent MCCI prototypic material experiments, CCI and VULCANO tests, one observes that concrete ablation behavior consistently depends on the concrete materials used in the experiments. Specifically, tests with Limestone-Common-Sand (LCS) concrete yielded isotropic concrete ablation; i.e., equal axial and radial concrete erosion. This is in comparison to anisotropic ablation in tests with Siliceous (SIL) concrete, where radial ablation was much larger than axial ablation. This was an unexpected result, because prior results of many MCCI simulant experiments indicated that nearly isotropic ablation was expected in prototypic material experiments regardless of concrete type. A new phenomenological model is proposed in this work based on a hypothesis that unifies the result of both previous simulant and prototypic material experiments; i.e., heat transfer area enhancement and delayed gas release caused by the presence of un-melted solid aggregate material that enters the molten pool. This model offers a logical and phenomenological explanation concerning anisotropic ablation as well as the capability to simulate anisotropic ablation. This model is implemented into the CORQUENCH code as part of this work. Comparisons of simulation results obtained with this new model to the CCI experiments for cases with siliceous concrete and anisotropic ablation show better agreement with the test data than the existing model.

  4. Characterization of core debris/concrete interactions for the Advanced Neutron Source

    SciTech Connect

    Hyman, C.R.; Taleyarkhan, R.P.

    1992-02-01

    This report provides the results of a recent study conducted to explore the molten core/concrete interaction (MCCI) issue for the Advanced Neutron Source (ANS). The need for such a study arises from the potential threats to reactor system integrity posed by MCCI. These threats include direct attack of the concrete basemat of the containment; generation and release of large quantities of gas that can pressurize the containment; the combustion threat of these gases; and the potential generation, release, and transport of radioactive aerosols to the environment.

  5. Experimental results of core-concrete interactions using molten steel with zirconium

    SciTech Connect

    Copus, E.R.; Blose, R.E.; Brockmann, J.E.; Gomez, R.D.; Lucero, D.A. )

    1990-07-01

    Four inductively sustained experiments, QT-D, QT-E, SURC-3, and SURC-3A, were performed in order to investigate the additional effects of zirconium metal oxidation on core debris-concrete interactions using molten stainless steel as the core debris simulant. The QT-D experiment ablated 18 cm of concrete axially during 50 minutes of interaction on limestone-common sand concrete using a 10 kg charge of 304 stainless steel to which 2 kg of zirconium metal was added subsequent to the onset of erosion. The QT-E experiment ablated 10 cm of limestone-common sand concrete axially and 10 cm radially during 35 minutes of sustained interaction using 50 kg of stainless steel and 10 kg of zirconium. The SURC-3 experiment had a 45 kg charge of stainless steel to which 1.1 kg of zirconium was subsequently added. SURC-3 axially eroded 33 cm of limestone concrete during two hours of interaction. The fourth experiment, SURC-3A, eroded 25 cm of limestone concrete axially and 9 cm radially during 90 minutes of sustained interaction. It utilized 40 kg of stainless steel and 2.2 kg of added zirconium as the charge material. All four experiments showed in a large increase in erosion rate, gas production, and aerosol release following the addition of Zr metal to the melt. In the SURC-3 and SURC-3A tests the measured erosion rates increased from 14 cm/hr to 27 cm/hr, gas release increased from 50 slpm to 100 slpm, and aerosol release increased from .02 q/sec to .04 q/sec. The effluent gas was composed of 80% CO, 10% CO{sub 2}, and 2% H{sub 2} before Zr addition and 92% CO, 4% CO{sub 2}, 4% H{sub 2} during the Zr interactions which lasted 10--20 minutes. Addition measurements indicated that the melt pool temperature ranged from 1600{degree}C--1800{degree} and that the aerosols produced were comprised primarily of Te and Fe oxides. 21 refs., 120 figs., 51 tabs.

  6. OECD/MCCI 2-D Core Concrete Interaction (CCI) tests : final report February 28, 2006.

    SciTech Connect

    Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S.

    2011-05-23

    Although extensive research has been conducted over the last several years in the areas of Core-Concrete Interaction (CCI) and debris coolability, two important issues warrant further investigation. The first issue concerns the effectiveness of water in terminating a CCI by flooding the interacting masses from above, thereby quenching the molten core debris and rendering it permanently coolable. This safety issue was investigated in the EPRI-sponsored Melt Attack and Coolability Experiments (MACE) program. The approach was to conduct large scale, integral-type reactor materials experiments with core melt masses ranging up to two metric tons. These experiments provided unique, and for the most part repeatable, indications of heat transfer mechanism(s) that could provide long term debris cooling. However, the results did not demonstrate definitively that a melt would always be completely quenched. This was due to the fact that the crust anchored to the test section sidewalls in every test, which led to melt/crust separation, even at the largest test section lateral span of 1.20 m. This decoupling is not expected for a typical reactor cavity, which has a span of 5-6 m. Even though the crust may mechanically bond to the reactor cavity walls, the weight of the coolant and the crust itself is expected to periodically fracture the crust and restore contact with the melt. Although crust fracturing does not ensure that coolability will be achieved, it nonetheless provides a pathway for water to recontact the underlying melt, thereby allowing other debris cooling mechanisms to proceed. A related task of the current program, which is not addressed in this particular report, is to measure crust strength to check the hypothesis that a corium crust would not be strong enough to sustain melt/crust separation in a plant accident. The second important issue concerns long-term, two-dimensional concrete ablation by a prototypic core oxide melt. As discussed by Foit the existing

  7. Independent analysis of selected core-concrete interaction and fission product release experiments with CORCON-MOD2 and VANESA

    SciTech Connect

    Greene, G.A.; Sanborn, Y.

    1986-01-01

    The discrepancies between experimental findings and the Reactor Safety Study predictions, as well as the rapidly developing data base enabling phenomenological modeling of core-concrete interactions and ex-vessel fission product release, have prompted the development of several new computer models of core-concrete interactions and fission product release during severe accidents. Two such models are the CORCON-MOD2 model of core-concrete interactions and the VANESA model of ex-vessel aerosol and fission product release during core-concrete interactions. The final judge on the adequacy of the development of models of core debris-concrete interactions is, of course, comparison of the model predictions with the results of experiments. The research into ex-vessel core debris behavior differs from research into many aspects of reactor accidents in that there are many experimental results for comparison. Comparisons of code predictions with results of tests using realistic temperatures and conditions should provide an indication of the progress that has been made and, with appropriately chosen tests, an indication of work that needs to be done. 9 refs., 6 figs., 5 tabs.

  8. OECD 2-D Core Concrete Interaction (CCI) tests : CCI-2 test plan, Rev. 0 January 31, 2004.

    SciTech Connect

    Farmer, M. T.; Kilsdonk, D. J.; Lomperski, S.; Aeschlimann, R. W.; Basu, S.

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. The first of these two tests, CCI-1, was conducted on December 19, 2003. This test investigated the interaction of a fully oxidized 400 kg PWR core melt, initially containing 8 wt % calcined siliceous concrete, with a specially designed two

  9. CORCON-MOD3: An integrated computer model for analysis of molten core-concrete interactions. User`s manual

    SciTech Connect

    Bradley, D.R.; Gardner, D.R.; Brockmann, J.E.; Griffith, R.O.

    1993-10-01

    The CORCON-Mod3 computer code was developed to mechanistically model the important core-concrete interaction phenomena, including those phenomena relevant to the assessment of containment failure and radionuclide release. The code can be applied to a wide range of severe accident scenarios and reactor plants. The code represents the current state of the art for simulating core debris interactions with concrete. This document comprises the user`s manual and gives a brief description of the models and the assumptions and limitations in the code. Also discussed are the input parameters and the code output. Two sample problems are also given.

  10. Fukushima Daiichi Unit 1 Ex-Vessel Prediction: Core Concrete Interaction

    SciTech Connect

    Robb, Kevin R; Farmer, Mitchell; Francis, Matthew W

    2015-01-01

    Lower head failure and corium concrete interaction were predicted to occur at Fukushima Daiichi Unit 1 (1F1) by several different system-level code analyses, including MELCOR v2.1 and MAAP5. Although these codes capture a wide range of accident phenomena, they do not contain detailed models for ex-vessel core melt behavior. However, specialized codes exist for analysis of ex-vessel melt spreading (e.g., MELTSPREAD) and long-term debris coolability (e.g., CORQUENCH). On this basis, an analysis was carried out to further evaluate ex-vessel behavior for 1F1 using MELTSPREAD and CORQUENCH. Best-estimate melt pour conditions predicted by MELCOR v2.1 and MAAP5 were used as input. MELTSPREAD was then used to predict the spatially dependent melt conditions and extent of spreading during relocation from the vessel. The results of the MELTSPREAD analysis are reported in a companion paper. This information was used as input for the long-term debris coolability analysis with CORQUENCH.

  11. Characterization of core debris/concrete interactions for the Advanced Neutron Source. ANS Severe Accident Analysis Program

    SciTech Connect

    Hyman, C.R.; Taleyarkhan, R.P.

    1992-02-01

    This report provides the results of a recent study conducted to explore the molten core/concrete interaction (MCCI) issue for the Advanced Neutron Source (ANS). The need for such a study arises from the potential threats to reactor system integrity posed by MCCI. These threats include direct attack of the concrete basemat of the containment; generation and release of large quantities of gas that can pressurize the containment; the combustion threat of these gases; and the potential generation, release, and transport of radioactive aerosols to the environment.

  12. Impact of Zr metal and coking reactions on the fission product aerosol release during MCCI (Molten Core Concrete Interactions)

    SciTech Connect

    Lee, M.; Davis, R.E.; Khatib-Rahbar, M.

    1987-01-01

    During a core meltdown accident in a light water reactor, molten core materials (corium) could leave the reactor vessel and interact with concrete. In this paper, the impact of the zirconium content of the corium pool and the coking reaction on the release of fission products during Molten Core Concrete Interactions (MCCI) are quantified using CORCON/MOD2 and VANESA computer codes. Detailed calculations show that the total aerosol generation is proportional to the zirconium content of the corium pool. Among the twelve fission product groups treated by the VANESA code, CsI, CsO/sub 2/ and Nb/sub 2/O/sub 5/ are completely released over the course of the core/concrete interaction, while an insignificant quantity of Mo, Ru and ZrO/sub 2/ are predicted to be released. The release of BaO, SrO and CeO/sub 2/ increase with increased Zr content, while the releases of Te and La/sub 2/O/sub 3/ are relatively unaffected by the Zr content of the corium pool. The impact of the coking reaction on the radiological releases is estimated to be significant; while the impact of the coking reaction on the aerosol production is insignificant.

  13. Core-concrete interactions using molten UO sub 2 with zirconium on a basaltic basemat: The SURC-2 experiment

    SciTech Connect

    Copus, E.R.; Brockmann, J.E.; Simpson, R.B.; Lucero, D.A. ); Blose, R.E. )

    1992-08-01

    An inductively heated experiment, SURC-2, using prototypic U0{sub 2}-ZrO{sub 2} materials was executed as part of the Integral Core-Concrete Interactions Experiments Program. The purpose of this experimental program was to measure and assess the variety of source terms produced during core debris/concrete interactions. These source terms include thermal energy released to both the reactor basemat and the containment environment, as well as flammable gas, condensable vapor and toxic or radioactive aerosols generated during the course of a severe reactor accident. The SURC-2 experiment eroded a total of 35 cm of basaltic concrete during 160 minutes of sustained interaction using 203.9 kg of prototypic U0{sub 2}-ZrO{sub 2} core debris material that included 18 kg of Zr metal and 3.4 kg of fission product simulants. The meltpool temperature ranged from 2400--1900{degrees}C during the first 50 minutes of the test followed by steady temperatures of 1750--1800{degrees}C during the middle portion of the test and increased temperatures of 1800--1900{degrees}C during the final 50 minutes of testing. The total erosion during the first 50 minutes was 15 cm with an additional 7 cm during the middle part of the test and 13 cm of ablation during the final 50 minutes. Comprehensive gas flowrates, gas compositions, and aerosol release rates were also measured during the SURC-2 test. When combined with the SURC-1 results, SURC-2 forms a complete data base for prototypic U0{sub 2}-ZrO{sub 2} core debris interactions with concrete.

  14. OECD MCCI project long-term 2-D molten core concrete interaction test design report, Rev. 0. September 30, 2002.

    SciTech Connect

    Farmer, M. T.; Kilsdonk, D. J.; Lomperski, S.; Aeschliman, R. W.; Basu, S.

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program at Argonne National Laboratory addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following two technical objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of the first program objective, the Small-Scale Water Ingression and Crust Strength (SSWICS) test series has been initiated to provide fundamental information on the ability of water to ingress into cracks and fissures that form in the debris during quench, thereby augmenting the otherwise conduction-limited heat transfer process. A test plan for Melt Eruption Separate Effects Tests (MESET) has also been developed to provide information on the extent of crust growth and melt eruptions as a function of gas sparging rate under well-controlled experiment conditions. In terms of the second program objective, the project Management Board (MB) has approved startup activities required to carry out

  15. Core-concrete interactions with overlying water pools. The WETCOR-1 test

    SciTech Connect

    Blose, R.E.; Powers, D.A.; Copus, E.R.; Brockmann, J.E.; Simpson, R.B.; Lucero, D.A.

    1993-11-01

    The WETCOR-1 test of simultaneous interactions of a high-temperature melt with water and a limestone/common-sand concrete is described. The test used a 34.1-kg melt of 76.8 w/o Al{sub 2}O{sub 3}, 16.9 w/o CaO, and 4.0 w/o SiO{sub 2} heated by induction using tungsten susceptors. Once quasi-steady attack on concrete by the melt was established, an attempt was made to quench the melt at 1850 K with 295 K water flowing at 57 liters per minute. Net power into the melt at the time of water addition was 0.61 {plus_minus} 0.19 W/cm{sup 3}. The test configuration used in the WETCOR-1 test was designed to delay melt freezing to the walls of the test fixture. This was done to test hypotheses concerning the inherent stability of crust formation when high-temperature melts are exposed to water. No instability in crust formation was observed. The flux of heat through the crust to the water pool maintained over the melt in the test was found to be 0.52 {plus_minus} 0.13 MW/m{sup 2}. Solidified crusts were found to attenuate aerosol emissions during the melt concrete interactions by factors of 1.3 to 3.5. The combination of a solidified crust and a 30-cm deep subcooled water pool was found to attenuate aerosol emissions by factors of 3 to 15.

  16. A simplified model of aerosol scrubbing by a water pool overlying core debris interacting with concrete. Final report

    SciTech Connect

    Powers, D.A.; Sprung, J.L.

    1993-11-01

    A classic model of aerosol scrubbing from bubbles rising through water is applied to the decontamination of gases produced during core debris interactions with concrete. The model, originally developed by Fuchs, describes aerosol capture by diffusion, sedimentation, and inertial impaction. This original model for spherical bubbles is modified to account for ellipsoidal distortion of the bubbles. Eighteen uncertain variables are identified in the application of the model to the decontamination of aerosols produced during core debris interactions with concrete by a water pool of specified depth and subcooling. These uncertain variables include properties of the aerosols, the bubbles, the water and the ambient pressure. Results are analyzed using a nonparametric, order statistical analysis that allows quantitative differentiation of stochastic and phenomenological uncertainty. The sampled values of the decontamination factors are used to construct estimated probability density functions for the decontamination factor at confidence levels of 50%, 90% and 95%. The decontamination factors for pools 30, 50, 100, 200, 300, and 500 cm deep and subcooling levels of 0, 2, 5, 10, 20, 30, 50, and 70{degrees}C are correlated by simple polynomial regression. These polynomial equations can be used to estimate decontamination factors at prescribed confidence levels.

  17. Scoping assessments of ATF impact on late-stage accident progression including molten core-concrete interaction

    NASA Astrophysics Data System (ADS)

    Farmer, M. T.; Leibowitz, L.; Terrani, K. A.; Robb, K. R.

    2014-05-01

    Simple scoping models that can be used to evaluate ATF performance under severe accident conditions have been developed. The methodology provides a fundamental technical basis (a.k.a. metric) based on the thermodynamic boundary for evaluating performance relative to that of traditional Zr-based claddings. The initial focus in this study was on UO2 fuel with the advanced claddings 310 SS, D9, FeCrAl, and SiC. The evaluation considered only energy release with concurrent combustible gas production from fuel-cladding-coolant interactions and, separately, molten core-concrete interactions at high temperatures. Other important phenomenological effects that can influence the rate and extent of cladding decomposition (e.g., eutectic interactions, degradation of other core constituents) were not addressed. For the cladding types addressed, potential combustible gas production under both in-vessel and ex-vessel conditions was similar to that for Zr. However, exothermic energy release from cladding oxidation was substantially less for iron-based alloys (by at least a factor of 4), and modestly less (by ∼20%) for SiC. Data on SiC-clad UO2 fuel performance under severe accident conditions are sparse in the literature; thus, assumptions on the nature of the cladding decomposition process were made in order to perform this initial screening evaluation. Experimental data for this system under severe accident conditions is needed for a proper evaluation and comparison to iron-based claddings.

  18. OECD MCCI project 2-D Core Concrete Interaction (CCI) tests : CCI-3 test data report-thermalhydraulic results. Rev. 0 October 15, 2005.

    SciTech Connect

    Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S.

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of a third long-term 2-D Core-Concrete Interaction (CCI) experiment designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-3 experiment, which was conducted on September 22, 2005. Test specifications for CCI-3 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 375

  19. OECD MCCI 2-D Core Concrete Interaction (CCI) tests : CCI-2 test data report-thermalhydraulic results, Rev. 0 October 15, 2004.

    SciTech Connect

    Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W.; Basu, S.

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten core-concrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-2 experiment, which was conducted on August 24, 2004. Test specifications for CCI-2 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg

  20. OECD MMCI 2-D Core Concrete Interaction (CCI) tests : CCCI-1 test data report-thermalhydraulic results. Rev 0 January 31, 2004.

    SciTech Connect

    Farmer, M. T.; Lomperski, S.; Aeschlimann, R. W.; Basu, S.

    2011-05-23

    The Melt Attack and Coolability Experiments (MACE) program addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. As a follow-on program to MACE, The Melt Coolability and Concrete Interaction Experiments (MCCI) project is conducting reactor material experiments and associated analysis to achieve the following objectives: (1) resolve the ex-vessel debris coolability issue through a program that focuses on providing both confirmatory evidence and test data for the coolability mechanisms identified in MACE integral effects tests, and (2) address remaining uncertainties related to long-term two-dimensional molten coreconcrete interactions under both wet and dry cavity conditions. Achievement of these two program objectives will demonstrate the efficacy of severe accident management guidelines for existing plants, and provide the technical basis for better containment designs for future plants. In terms of satisfying these objectives, the Management Board (MB) approved the conduct of two long-term 2-D Core-Concrete Interaction (CCI) experiments designed to provide information in several areas, including: (i) lateral vs. axial power split during dry core-concrete interaction, (ii) integral debris coolability data following late phase flooding, and (iii) data regarding the nature and extent of the cooling transient following breach of the crust formed at the melt-water interface. This data report provides thermal hydraulic test results from the CCI-1 experiment, which was conducted on December 19, 2003. Test specifications for CCI-1 are provided in Table 1-1. This experiment investigated the interaction of a fully oxidized 400 kg

  1. Impact of core-concrete interactions in the Mark I containment drywell on containment integrity and failure of the drywell liner

    SciTech Connect

    Greene, G.A.; Perkins, K.R.; Hodge, S.A.

    1985-01-01

    Previous containment analyses of the Mark I BWR have considered the ..gamma..-mode of containment failure as the dominant mode. The ..gamma..-mode is over-pressure failure of the drywell linear resulting in release of fission products and aerosols directly into the reactor building. The failure pressure for this event has been estimated at 132 psia. However, results from the SASA program analyses of the Mark I BWR have indicated that high temperatures in the drywell during ex-vessel core-concrete interactions may result in containment failure due to seal degradation prior to gross failure due to over-pressurization. It has become evident that a third mode of drywell failure must be considered under these specified accident conditions, in addition to the gross over-pressure failure and the leak-before-failure modes. This third mode of failure is local ablation of the steel drywell liner due to contact with the molten corium. In order to assess the drywell liner response to heat transfer from a pool of molten core debris during a core-concrete interaction, a calculational procedure consisting of both code calculations and hand calculations was developed. The general methodology was to calculate the melting attack on the steel liner by molten core debris that is simultaneously attacking the drywell concrete floor. 15 refs.

  2. Core-concrete molten pool dynamics and interfacial heat transfer. [PWR; BWR

    SciTech Connect

    Benjamin, A.S.

    1980-01-01

    Theoretical models are derived for the heat transfer from molten oxide pools to an underlying concrete surface and from molten steel pools to a general concrete containment. To accomplish this, two separate effects models are first developed, one emphasizing the vigorous agitation of the molten pool by gases evolving from the concrete and the other considering the insulating effect of a slag layer produced by concrete melting. The resulting algebraic expressions, combined into a general core-concrete heat transfer representation, are shown to provide very good agreement with experiments involving molten steel pours into concrete crucibles.

  3. Chloride contamination of concrete by interaction with PVC combustion gases

    SciTech Connect

    Climent-Llorca, M.A.; Viqueira-Perez, E.; Vera-Almenar, G. de; Lopez-Atalaya, M.M.

    1998-02-01

    Chloride contamination of concrete by interaction with PVC combustion gases has been studied in a small-scale testing chamber, which allows simulating the conditions probably prevailing in PVC fires of different magnitude through variation of the quotient between mass of burnt PVC and exposed concrete surface (PVC/S). In all cases, a steep gradient of chloride concentration with depth is found after the fire: most chloride is detected in the outermost layer at depths below 5 mm. Surface chloride contents (within 5 mm) for prestressed and reinforced concretes, tested with a high (PVC/S) ratio, are as high as 2.5 and 5% by weight of cement, respectively. Chloride concentrations in concrete near the steels are below the corrosion thresholds after the fire, but they can rise by diffusion to values able to induce rebar corrosion, especially if concrete is exposed to a humid atmosphere.

  4. Application of Core Dynamics Modeling to Core-Mantle Interactions

    NASA Technical Reports Server (NTRS)

    Kuang, Weijia

    2003-01-01

    Observations have demonstrated that length of day (LOD) variation on decadal time scales results from exchange of axial angular momentum between the solid mantle and the core. There are in general four core-mantle interaction mechanisms that couple the core and the mantle. Of which, three have been suggested likely the dominant coupling mechanism for the decadal core-mantle angular momentum exchange, namely, gravitational core-mantle coupling arising from density anomalies in the mantle and in the core (including the inner core), the electromagnetic coupling arising from Lorentz force in the electrically conducting lower mantle (e.g. D-layer), and the topographic coupling arising from non-hydrostatic pressure acting on the core-mantle boundary (CMB) topography. In the past decades, most effort has been on estimating the coupling torques from surface geomagnetic observations (kinematic approach), which has provided insights on the core dynamical processes. In the meantime, it also creates questions and concerns on approximations in the studies that may invalidate the corresponding conclusions. The most serious problem is perhaps the approximations that are inconsistent with dynamical processes in the core, such as inconsistencies between the core surface flow beneath the CMB and the CMB topography, and that between the D-layer electric conductivity and the approximations on toroidal field at the CMB. These inconsistencies can only be addressed with numerical core dynamics modeling. In the past few years, we applied our MoSST (Modular, Scalable, Self-consistent and Three-dimensional) core dynamics model to study core-mantle interactions together with geodynamo simulation, aiming at assessing the effect of the dynamical inconsistencies in the kinematic studies on core-mantle coupling torques. We focus on topographic and electromagnetic core-mantle couplings and find that, for the topographic coupling, the consistency between the core flow and the CMB topography is

  5. Characterization of debris/concrete interactions for advanced research reactor and commercial BWR severe accidents

    SciTech Connect

    Hyman, C.R.; Taleyarkhan, R.P.; Greene, S.R.

    1991-01-01

    The core concrete interaction (CCI) is an important phase of any severe accident where the reactor vessel has failed and core debris is relocated onto the containment basemat. In recent calculations performed at the Oak Ridge National Laboratory (ORNL), CCI has been studied for severe accidents occurring in a commercial Boiling Water Reactor (BWR) and in a high-power density Department of Energy (DOE) research reactor that is currently in the conceptual design stage. Because of differences in the debris decay heating level, core debris composition and inventory, and containment design, the characteristics of the resulting CCI and containment response are different for the two reactor types. Furthermore, proper selection of the basemat concrete type and the provision of an overlying water pool are found to be significant CCI mitigating factors for the research reactor and thus constitute important design considerations for any future reactor type. 10 refs., 4 figs., 1 tab.

  6. Interactions between concrete and brine at the Waste Isolation Pilot Plant (WIPP) Site, New Mexico

    SciTech Connect

    Lambert, S.J.; Nowak, E.J. ); Wakeley, L.D.; Poole, T.S. . Structures Lab.)

    1992-05-01

    A concrete liner emplaced in 1984 in a shaft at the Waste Isolation Pilot Plant has served as a natural laboratory for observing interactions among concrete, evaporite rocks, and brine. During a routine inspection of the liner in the spring of 1990, discoloration, deposition of secondary salts, wet areas with exposed aggregate grains, softening of paste, surficial spalling, and cracking were observed locally on the concrete surface of the liner. Some construction joints showed apparent leakage of brine from behind the liner, which was nominally 50 cm thick. Seepage brines were nearly saturated relative to CaCI{sub 2} and contained lesser amounts of MgCI{sub 2} and KCI, and minor NaCl. The liner surface was locally altered to a 1-2 cm friable hygroscopic layer containing little cement paste; concrete cores (7 or 10 cm diameter) through the liner at depths of 248, 254, 255, and 271 m showed similar degrees of alteration at the liner/rock interface. The most profound alteration of concrete was developed in a {approximately}7 cm zone subparallel to and straddling the construction joint cored at a depth of {approximately}254.5 m. This zone was extensively microfractured, transected aggregate grains, and contained brucite, gypsum, magnesium hydroxychloride hydrate, and locally calcium chloroaluminate instead of the usual phases of hydrated portland cement. Several mechanisms of chemical degradation have been proposed, the most likely being attack by magnesium ions.

  7. Interactions between concrete and brine at the Waste Isolation Pilot Plant (WIPP) Site, New Mexico

    SciTech Connect

    Lambert, S.J.; Nowak, E.J.; Wakeley, L.D.; Poole, T.S.

    1991-12-31

    A concrete liner emplaced in 1984 in a shaft at the Waste Isolation Pilot Plant has served as a natural laboratory for observing interactions among concrete, evaporite rocks, and brine. During a routine inspection of the liner in the spring of 1990, discoloration, deposition of secondary salts, wet areas with exposed aggregate grains, softening of paste, surficial spalling, and cracking were observed locally on the concrete surface of the liner. Some construction joints showed apparent leakage of brine from behind the liner, which was nominally 50 cm thick. Seepage brines were nearly saturated relative to CaCl{sub 2} and contained lesser amounts of MgCl{sub 2} and KCl, and minor NaCl. The liner surface was locally altered to a 1--2 cm friable hygroscopic layer containing little cement paste; concrete cores (7 or 10 cm diameter) through the liner at depths of 248, 254, 255, and 271 m showed similar degrees of alteration at the liner/rock interface. The most profound alteration of concrete was developed in a {approximately}7 cm zone subparallel to and straddling the construction joint cored at a depth of {approximately}254.5 m. This zone was extensively microfractured, transected aggregate grains, and contained brucite, gypsum, magnesium hydroxychloride hydrate, and locally calcium chloroaluminate instead of the usual phases of hydrated portland cement. Several mechanisms of chemical degradation have been proposed, the most likely being attack by magnesium ions.

  8. Experimental and analytical studies of sodium interactions with various concretes. [LMFBR

    SciTech Connect

    Suo-Anttila, A.; Smaardyk, J.E.

    1982-01-01

    Mechanistic models of sodium/concrete interactions are described. The SCAM model of interactions with basaltic concrete is being verified by experiments. Modelling of sodium interactions with limestone concrete is still at a preliminary stage but shows promise of being able to predict quantitatively the experimental data. Comparisons with experimental data are presented.

  9. A Scoping Analysis Of The Impact Of SiC Cladding On Late-Phase Accident Progression Involving Core–Concrete Interaction

    SciTech Connect

    Farmer, M. T.

    2015-11-01

    The overall objective of the current work is to carry out a scoping analysis to determine the impact of ATF on late phase accident progression; in particular, the molten core-concrete interaction portion of the sequence that occurs after the core debris fails the reactor vessel and relocates into containment. This additional study augments previous work by including kinetic effects that govern chemical reaction rates during core-concrete interaction. The specific ATF considered as part of this study is SiC-clad UO2.

  10. Ice Core Dating Software for Interactive Dating of Ice Cores

    NASA Astrophysics Data System (ADS)

    Kurbatov, A. V.; Mayewski, P. A.; Abdul Jawad, B. S.

    2005-12-01

    Scientists involved in ice core dating are well familiar with the problem of identification and recording the depth of annual signals using stable isotopes, glaciochemistry, ECM (electrical conductivity), DEP (dielectric properties) and particle counter data. Traditionally all parameters used for ice core dating were plotted as a function of depth, printed and after years were marked on the paper, converted to depth vs. age time scale. To expedite this tedious and manual process we developed interactive computer software, Ice core Dating (ICD) program. ICD is written in Java programming language, and uses GPL and GPL site licensed graphic libraries. The same 3.5 Mb in size pre-compiled single jar file, that includes all libraries and application code, was successfully tested on WinOS, Mac OSX, Linux, and Solaris operating systems running Java VM version 1.4. We have followed the modular design philosophy in our source code so potential integration with other software modules, data bases and server side distributed computer environments can be easily implemented. We expect to continue development of new suites of tools for easy integration of ice core data with other available time proxies. ICD is thoroughly documented and comes with a technical reference and cookbook that explains the purpose of the software and its many features, and provides examples to help new users quickly become familiar with the operation and philosophy of the software. ICD is available as a free download from the Climate Change Institute web site ( under the terms of GNU GPL public license.

  11. Geodynamo Modeling of Core-Mantle Interactions

    NASA Technical Reports Server (NTRS)

    Kuang, Wei-Jia; Chao, Benjamin F.; Smith, David E. (Technical Monitor)

    2001-01-01

    Angular momentum exchange between the Earth's mantle and core influences the Earth's rotation on time scales of decades and longer, in particular in the length of day (LOD) which have been measured with progressively increasing accuracy for the last two centuries. There are four possible coupling mechanisms for transferring the axial angular momentum across the core-mantle boundary (CMB): viscous, magnetic, topography, and gravitational torques. Here we use our scalable, modularized, fully dynamic geodynamo model for the core to assess the importance of these torques. This numerical model, as an extension of the Kuang-Bloxham model that has successfully simulated the generation of the Earth's magnetic field, is used to obtain numerical results in various physical conditions in terms of specific parameterization consistent with the dynamical processes in the fluid outer core. The results show that depending on the electrical conductivity of the lower mantle and the amplitude of the boundary topography at CMB, both magnetic and topographic couplings can contribute significantly to the angular momentum exchange. This implies that the core-mantle interactions are far more complex than has been assumed and that there is unlikely a single dominant coupling mechanism for the observed decadal LOD variation.

  12. In situ interaction between different concretes and Opalinus Clay

    NASA Astrophysics Data System (ADS)

    Jenni, A.; Mäder, U.; Lerouge, C.; Gaboreau, S.; Schwyn, B.

    Interactions between cementitious materials and claystone are driven by chemical gradients in pore water and might lead to mineralogical modifications in both materials. In the context of a radioactive waste repository, this alteration might influence safety-relevant clay properties like swelling pressure, permeability, or specific retention. In this study, interfaces of Opalinus Clay, a potential host-rock in Switzerland, and three concrete formulations emplaced in the Cement-Clay Interaction (CI) Experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) were analysed after 2.2 years of interaction. Sampling techniques with interface stabilisation followed by inclined intersection drilling were developed. Element distribution maps of the concrete-clay interfaces show complex zonations like sulphur enrichment, zones depleted in Ca but enriched in Mg, strong Mg enrichment adjacent to the interface, or carbonation. Consistently, the carbonated zone shows a reduced porosity. Properties of the complex zonation strongly depend on cement properties like water content and pH (ordinary Portland cement vs. low-pH cement). An increased Ca or Mg content in the first 100 μm next to the interface is observed in Opalinus Clay. The cation occupancy of clay exchanger phases next to the ordinary Portland cement interface is depleted in Mg, but enriched in Na, whereas porosity shows no changes at all. The current data suggests migration of CO2/HCO3-, SO42-, and Mg species from clay into cement. pH decrease in the cement next to the interface leads to instability of ettringite, and the sulphate liberated diffuses towards higher pH regions (away from the interface), where additional ettringite can form.

  13. Refocusing core intuitions: A concretizing role for analogy in conceptual change

    NASA Astrophysics Data System (ADS)

    Brown, David E.

    1993-12-01

    This article outlines a theoretical framework for viewing students' conceptions and the effect of analogies on students' conceptions. There are several points involved in this perspective: (a) Components of students' conceptions can be considered to be at various levels - verbal-symbolic knowledge, conscious models, implicit models, and core intuitions. (b) Components at the deeper, less articulated levels (especially core intuitions) are particularly entrenched. (c) Conceptual change in cases involving core intuitions can be considered to be the adjustment of attributive clusters for a class of situations. (d) In order to change the attributive cluster for a target situation, the target must be enriched with new concrete entities or features, providing nuclei for the reattribution of agency. (e) Analogies can help with this reattribution or refocusing by helping the student enrich his or her representation of the target situation.

  14. Core networks for visual-concrete and abstract thought content: a brain electric microstate analysis.

    PubMed

    Lehmann, Dietrich; Pascual-Marqui, Roberto D; Strik, Werner K; Koenig, Thomas

    2010-01-01

    Commonality of activation of spontaneously forming and stimulus-induced mental representations is an often made but rarely tested assumption in neuroscience. In a conjunction analysis of two earlier studies, brain electric activity during visual-concrete and abstract thoughts was studied. The conditions were: in study 1, spontaneous stimulus-independent thinking (post-hoc, visual imagery or abstract thought were identified); in study 2, reading of single nouns ranking high or low on a visual imagery scale. In both studies, subjects' tasks were similar: when prompted, they had to recall the last thought (study 1) or the last word (study 2). In both studies, subjects had no instruction to classify or to visually imagine their thoughts, and accordingly were not aware of the studies' aim. Brain electric data were analyzed into functional topographic brain images (using LORETA) of the last microstate before the prompt (study 1) and of the word-type discriminating event-related microstate after word onset (study 2). Conjunction analysis across the two studies yielded commonality of activation of core networks for abstract thought content in left anterior superior regions, and for visual-concrete thought content in right temporal-posterior inferior regions. The results suggest that two different core networks are automatedly activated when abstract or visual-concrete information, respectively, enters working memory, without a subject task or instruction about the two classes of information, and regardless of internal or external origin, and of input modality. These core machineries of working memory thus are invariant to source or modality of input when treating the two types of information. PMID:19646538

  15. Laboratory-scale sodium-carbonate aggregate concrete interactions. [LMFBR

    SciTech Connect

    Westrich, H.R.; Stockman, H.W.; Suo-Anttila, A.

    1983-09-01

    A series of laboratory-scale experiments was made at 600/sup 0/C to identify the important heat-producing chemical reactions between sodium and carbonate aggregate concretes. Reactions between sodium and carbonate aggregate were found to be responsible for the bulk of heat production in sodium-concrete tests. Exothermic reactions were initiated at 580+-30/sup 0/C for limestone and dolostone aggregates as well as for hydrated limestone concrete, and at 540+-10/sup 0/C for dehydrated limestone concrete, but were ill-defined for dolostone concrete. Major reaction products included CaO, MgO, Na/sub 2/CO/sub 3/, Na/sub 2/O, NaOH, and elemental carbon. Sodium hydroxide, which forms when water is released from cement phases, causes slow erosion of the concrete with little heat production. The time-temperature profiles of these experiments have been modeled with a simplified version of the SLAM computer code, which has allowed derivation of chemical reaction rate coefficients.

  16. Seismic deformation analysis of a rockfill dam with a bituminous concrete core

    NASA Astrophysics Data System (ADS)

    Ghahreman Nejad, Behrooz; Soden, Phillip; Taiebat, Hossein; Murphy, Steve

    2010-06-01

    This paper reports the results of seismic deformation analyses of Shur River Dam, which is an 84 m high water retaining rockfill embankment with a bituminous concrete core. The proposed Shur River Dam is located in a region of high seismicity in Kerman province, Iran. The purpose of the dam is to store raw and process water for use in the Sarcheshmeh Copper Production Complex. The maximum crest settlement of the dam under three earthquake loadings was evaluated using simplified procedures and numerical analysis. Plane strain, dynamic deformation analysis of the Shur Dam has been performed using the commercial software FLAC and its built-in Mohr-Coulomb elastic-plastic model. The main objective of these analyses has been to identify the earthquake induced movements that could lead to uncontrolled release of water. The predicted deformations are compared with the results of simplified analyses and the observed displacements in other embankment dams [1] during past earthquakes. The relative movement of the asphaltic core with respect to the rockfill material on either side of the core was also studied.

  17. Adhesive liquid core optical fibers for crack detection and repairs in polymer and concrete matrices

    NASA Astrophysics Data System (ADS)

    Dry, Carolyn M.

    1995-04-01

    This work is an investigation into the feasibility of using liquid core optical fibers for the detection and self repair of cracking in cement or polymer materials generated by dynamic or static loading. These experiments rely on our current research sponsored by the National Science Foundation. It combines that work on the concept of internal adhesive delivery from hollow fibers for repair with nondestructive fiber optic analysis of the crack localization and volume within the same system. The need to monitor the internal state of civil structures and materials is great. Existing instrumentation techniques that mainly rely on magnetism, electricity, or stress gauges are limited if used for remote measurements in concrete or composites. They are sensitive to electrical magnetic noises and they degrade in the environment over time. Optical fibers are attractive because they are immune to electromagnetic interference and are sensitive over long distances. The combination of the ability to remotely measure crack occurrence in real time and determine the location and volume of crack damage in the matrix is unique in the field of optic sensors (or any sensors in general). The combination of this with crack repair, rebonding of any detached or broken fibers, and replenishment of liquid core chemicals, when necessary, make this a potentially powerful sensing and repair tool. Work on this research topic of the combination sponsored by the University of Illinois, looks very promising as a rapid innovative advance.

  18. Clogging evaluation of porous asphalt concrete cores in conjunction with medical x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Su, Yu-Min; Hsu, Chen-Yu; Lin, Jyh-Dong

    2014-03-01

    This study was to assess the porosity of Porous Asphalt Concrete (PAC) in conjunction with a medical X-ray computed tomography (CT) facility. The PAC was designed as the surface course to achieve the target porosity 18%. There were graded aggregates, soils blended with 50% of coarse sand, and crushed gravel wrapped with geotextile compacted and served as the base, subbase, and infiltration layers underneath the PAC. The test site constructed in 2004 is located in Northern of Taiwan in which the daily traffic has been light and limited. The porosity of the test track was investigated. The permeability coefficient of PAC was found severely degraded from 2.2×10-1 to 1.2×10-3 -cm/sec, after nine-year service, while the permeability below the surface course remained intact. Several field PAC cores were drilled and brought to evaluate the distribution of air voids by a medical X-ray CT nondestructively. The helical mode was set to administrate the X-ray CT scan and two cross-sectional virtual slices were exported in seconds for analyzing air voids distribution. It shows that the clogging of voids occurred merely 20mm below the surface and the porosity can reduce as much about 3%. It was also found that the roller compaction can decrease the porosity by 4%. The permeability reduction in this test site can attribute to the voids of PAC that were compacted by roller during the construction and filled by the dusts on the surface during the service.

  19. Detection of Chemical Interactions Between the Core and Mantle

    NASA Astrophysics Data System (ADS)

    Walker, R. J.

    2002-05-01

    Unambiguous detection of chemical interaction between Earth's outer core and lower mantle would be a major breakthrough in understanding mass transport within the mantle. Although most geophysicists and geochemists accept the possibilities of both slab penetration into the lower mantle, and upwelling of hot plumes from the lower mantle into the upper mantle, as yet, no unambiguous geochemical signal can be tied directly to the lower mantle or outer core. Demonstration of an outer core component in mantle-derived materials would prove that at least some matter traverses the distance between the core and mantle. Detection of chemical interaction between the core and mantle is potentially possible via the study of a rather limited suite of elements. There are at least two qualifying criteria for such elements: 1) contrast in concentration between core and mantle such that modest chemical interaction between the metallic core and silicate mantle would be detectible in the "contaminated" or "altered" silicate, 2) the relative abundances of two or more associated elements must record a uniquely core signature. Elements that may meet these requirements include the highly siderophile elements (Re, Au, Pt, Pd, Ir, Rh, Ru, Os) and some moderately siderophile elements (e.g. Au and W). Isotopic systems are of greatest interest in prosecuting this task because characteristic isotopic signals may be immune to subsequent processing in the mantle or crust. Pros and cons in application, and overviews of existing data will be presented for three isotopic systems. Inner core-outer core fractionation may have led to Pt/Os and Re/Os ratios in the outer core that can be generated only by liquid metal-solid metal interaction. Depending on the age of the inner core and the partitioning characteristics of Pt-Re-Os, an outer core signature may be recorded by the long-lived 190Pt-186Os and 187Re-187Os systems. 2 and 3) Core-mantle segregation likely fractionated Hf from W and Pd from Ag

  20. Effective Interactions from No Core Shell Model

    SciTech Connect

    Dikmen, E.; Lisetskiy, A. F.; Barrett, B. R.; Navratil, P.; Vary, J. P.

    2008-11-11

    We construct the many-body effective Hamiltonian for pf-shell by carrying out 2({Dirac_h}/2{pi}){omega}. NCSM calculations at the 2-body cluster level. We demonstrate how the effective Hamiltonian derived from realistic nucleon-nucleon (NN) potentials for the 2({Dirac_h}/2{pi}){omega} NCSM space should be modified to properly account for the many-body correlations produced by truncating to the major pf-shell. We obtain two-body effective interactions for the pf-shell by using direct projection and use them to reproduce the results of large scale NCSM for other light Ca isotopes.

  1. The Interaction of Concreteness and Phonological Similarity in Verbal Working Memory

    PubMed Central

    Acheson, Daniel J.; Postle, Bradley R.; MacDonald, Maryellen C.

    2010-01-01

    Although phonological representations have been a primary focus of verbal working memory research, lexical-semantic manipulations also influence performance. In the present study, the authors investigated whether a classic phenomenon in verbal working memory, the phonological similarity effect (PSE), is modulated by a lexical-semantic variable, word concreteness. Phonological overlap and concreteness were factorially manipulated in each of four experiments across which presentation modality (Experiments 1 and 2: visual presentation; Experiments 3 and 4: auditory presentation) and concurrent articulation (present in Experiments 2 and 4) were manipulated. In addition to main effects of each variable, results show a Phonological Overlap × Concreteness interaction whereby the magnitude of the PSE is greater for concrete word lists relative to abstract word lists. This effect is driven by superior item memory for nonoverlapping, concrete lists and is robust to the modality of presentation and concurrent articulation. These results demonstrate that in verbal working memory tasks, there are multiple routes to the phonological form of a word and that maintenance and retrieval occur over more than just a phonological level. PMID:20053042

  2. Interaction of RNA polymerase II with acetylated nucleosomal core particles

    SciTech Connect

    Pineiro, M.; Gonzalez, P.J.; Hernandez, F.; Palacian, E. )

    1991-05-31

    Chemical acetylation of nucleosomal cores is accompanied by an increase in their efficiency as in vitro transcription templates. Low amounts of acetic anhydride cause preferential modification of the amino-terminal tails of core histones. Modification of these domains, which causes moderate structural effects, is apparently correlated with the observed stimulation of RNA synthesis. In contrast, extensive modification of the globular regions of core histones, which is accompanied by a large structural relaxation of the particle, causes little additional effect on transcription. Acetylation of the amino-terminal domains of histones might stimulate transcription by changing the interaction of the histone tails with components of the transcriptional machinery.

  3. Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

    SciTech Connect

    McGinnis, M. J.; Pessiki, S.

    2006-03-06

    The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.

  4. Outer Shock Interaction in Young Core-Collapse SNRs

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Joon

    2014-01-01

    Studying the environments in which core-collapse supernovae (SNe) explode and then subsequently evolve is essential to establish the nature of the mass loss and the explosion of the progenitor star. The spatial structure of the outer shock in young core-collapse SNRs provides an opportunity to study the nature of the medium into which the remnant has been expanding. We present our X-ray study of the outer shocks in young core-collapse SNRs in our Galaxy. For Cas A and G292.0+1.8, we find that both remnants have been likely interacting with dense red supergiant winds. For other remnants with bright thermal X-ray emission from the shell, we suggest that they are interacting with pre-existing circumstellar structure. We discuss the nature of the winds and the progenitor stars.

  5. Role of ligand-ligand vs. core-core interactions in gold nanoclusters.

    PubMed

    Milowska, Karolina Z; Stolarczyk, Jacek K

    2016-05-14

    The controlled assembly of ligand-coated gold nanoclusters (NCs) into larger structures paves the way for new applications ranging from electronics to nanomedicine. Here, we demonstrate through rigorous density functional theory (DFT) calculations employing novel functionals accounting for van der Waals forces that the ligand-ligand interactions determine whether stable assemblies can be formed. The study of NCs with different core sizes, symmetry forms, ligand lengths, mutual crystal orientations, and in the presence of a solvent suggests that core-to-core van der Waals interactions play a lesser role in the assembly. The dominant interactions originate from combination of steric effects, augmented by ligand bundling on NC facets, and related to them changes in electronic properties induced by neighbouring NCs. We also show that, in contrast to standard colloidal theory approach, DFT correctly reproduces the surprising experimental trends in the strength of the inter-particle interaction observed when varying the length of the ligands. The results underpin the importance of understanding NC interactions in designing gold NCs for a specific function. PMID:27097887

  6. Earthquake Resilient Tall Reinforced Concrete Buildings at Near-Fault Sites Using Base Isolation and Rocking Core Walls

    NASA Astrophysics Data System (ADS)

    Calugaru, Vladimir

    This dissertation pursues three main objectives: (1) to investigate the seismic response of tall reinforced concrete core wall buildings, designed following current building codes, subjected to pulse type near-fault ground motion, with special focus on the relation between the characteristics of the ground motion and the higher-modes of response; (2) to determine the characteristics of a base isolation system that results in nominally elastic response of the superstructure of a tall reinforced concrete core wall building at the maximum considered earthquake level of shaking; and (3) to demonstrate that the seismic performance, cost, and constructability of a base-isolated tall reinforced concrete core wall building can be significantly improved by incorporating a rocking core-wall in the design. First, this dissertation investigates the seismic response of tall cantilever wall buildings subjected to pulse type ground motion, with special focus on the relation between the characteristics of ground motion and the higher-modes of response. Buildings 10, 20, and 40 stories high were designed such that inelastic deformation was concentrated at a single flexural plastic hinge at their base. Using nonlinear response history analysis, the buildings were subjected to near-fault seismic ground motions as well as simple close-form pulses, which represented distinct pulses within the ground motions. Euler-Bernoulli beam models with lumped mass and lumped plasticity were used to model the buildings. Next, this dissertation investigates numerically the seismic response of six seismically base-isolated (BI) 20-story reinforced concrete buildings and compares their response to that of a fixed-base (FB) building with a similar structural system above ground. Located in Berkeley, California, 2 km from the Hayward fault, the buildings are designed with a core wall that provides most of the lateral force resistance above ground. For the BI buildings, the following are investigated

  7. Comparison of core sampling and visual inspection for assessment of concrete sewer pipe condition.

    PubMed

    Stanić, N; de Haan, C; Tirion, M; Langeveld, J G; Clemens, F H L R

    2013-01-01

    Sewer systems are costly to construct and even more costly to replace, requiring proper asset management. Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection by closed circuit television (CCTV) and core sampling are among the methods mostly applied to assess sewer pipe condition. This paper compares visual inspection and drill core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of The Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and core sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill core analysis. PMID:23752377

  8. Weak-interaction processes in core-collapse supernovae

    SciTech Connect

    Langanke, K.

    2015-02-24

    Weak interaction processes play an important role for the dynamics of a core-collapse supernova. Due to progress of nuclear modeling and constrained by data it has been possible to improve the rates of these processes for supernova conditions decisively. This manuscript describes the recent advances and the current status in deriving electron capture rates on nuclei and of inelastic neutrino-nucleus scattering for applications in supernova simulations and briefly discusses their impact on such studies.

  9. Iron-carbonate interaction at Earth's core-mantle boundary

    NASA Astrophysics Data System (ADS)

    Dorfman, S. M.; Badro, J.; Nabiei, F.; Prakapenka, V.; Gillet, P.

    2015-12-01

    Carbon storage and flux in the deep Earth are moderated by oxygen fugacity and interactions with iron-bearing phases. The amount of carbon stored in Earth's mantle versus the core depends on carbon-iron chemistry at the core-mantle boundary. Oxidized carbonates subducted from Earth's surface to the lowermost mantle may encounter reduced Fe0 metal from disproportionation of Fe2+ in lower mantle silicates or mixing with the core. To understand the fate of carbonates in the lowermost mantle, we have performed experiments on sandwiches of single-crystal (Ca0.6Mg0.4)CO3 dolomite and Fe foil in the laser-heated diamond anvil cell at lower mantle conditions of 49-110 GPa and 1800-2500 K. Syntheses were conducted with in situ synchrotron X-ray diffraction to identify phase assemblages. After quench to ambient conditions, samples were sectioned with a focused Ga+ ion beam for composition analysis with transmission electron microscopy. At the centers of the heated spots, iron melted and reacted completely with the carbonate to form magnesiowüstite, iron carbide, diamond, magnesium-rich carbonate and calcium carbonate. In samples heated at 49 and 64 GPa, the two carbonates exhibit a eutectoid texture. In the sample heated at 110 GPa, the carbonates form rounded ~150-nm-diameter grains with a higher modal proportion of interspersed diamonds. The presence of reduced iron in the deep lower mantle and core-mantle boundary region will promote the formation of diamonds in carbonate-bearing subducted slabs. The complete reaction of metallic iron to oxides and carbides in the presence of mantle carbonate supports the formation of these phases at the Earth's core-mantle boundary and in ultra-low velocity zones.

  10. Resolving 20 Years of Inconsistent Interactions Between Lexical Familiarity and Orthography, Concreteness, and Polysemy

    PubMed Central

    Gernsbacher, Morton Ann

    2015-01-01

    Numerous word recognition studies conducted over the past 2 decades are examined. These studies manipulated lexical familiarity by presenting words of high versus low printed frequency and most reported an interaction between printed frequency and one of several second variables, namely, orthographic regularity, semantic concreteness, or polysemy. However, the direction of these interactions was inconsistent from study to study. Six new experiments clarify these discordant results. The first two demonstrate that words of the same low printed frequency are not always equally familiar to subjects. Instead, subjects’ ratings of “experiential familiarity” suggest that many of the low-printed-frequency words used in prior studies varied along this dimension. Four lexical decision experiments reexamine the prior findings by orthogonally manipulating lexical familiarity, as assessed by experiential familiarity ratings, with bigram frequency, semantic concreteness, and number of meanings. The results suggest that of these variables, only experiential familiarity reliably affects word recognition latencies. This in turn suggests that previous inconsistent findings are due to confounding experiential familiarity with a second variable. PMID:6242753

  11. Shear strength of non-shear reinforced concrete elements. Part 3: Prestressed hollow-core slabs

    SciTech Connect

    Hoang, L.C.

    1997-12-31

    This paper deals with the shear strength of prestressed hollow-core slabs determined by the theory of plasticity. Two failure mechanisms are considered in order to derive the solutions. In the case of sliding failure in a diagonal crack, the shear strength is determined by means of the crack sliding model developed by Jin-Ping Zhang. The model takes into account the resistance against the formation of cracks due to prestressing as well as the variation of the prestressing force in the transfer zone. Due to the fact that the anchorage of the reinforcement takes place by bond, a rotation failure, which is indeed by a crack formed at the support with subsequent slip of the reinforcement, is also considered. This failure mode is likely to occur in cases with a high prestressing force combined with a short shear span. The theoretical calculations are compared with test results form the literature. A good agreement has been found.

  12. Baryon-Baryon Interactions ---Nijmegen Extended-Soft-Core Models---

    NASA Astrophysics Data System (ADS)

    Rijken, T. A.; Nagels, M. M.; Yamamoto, Y.

    We review the Nijmegen extended-soft-core (ESC) models for the baryon-baryon (BB) interactions of the SU(3) flavor-octet of baryons (N, Lambda, Sigma, and Xi). The interactions are basically studied from the meson-exchange point of view, in the spirit of the Yukawa-approach to the nuclear force problem [H. Yukawa, ``On the interaction of Elementary Particles I'', Proceedings of the Physico-Mathematical Society of Japan 17 (1935), 48], using generalized soft-core Yukawa-functions. These interactions are supplemented with (i) multiple-gluon-exchange, and (ii) structural effects due to the quark-core of the baryons. We present in some detail the most recent extended-soft-core model, henceforth referred to as ESC08, which is the most complete, sophisticated, and successful interaction-model. Furthermore, we discuss briefly its predecessor the ESC04-model [Th. A. Rijken and Y. Yamamoto, Phys. Rev. C 73 (2006), 044007; Th. A. Rijken and Y. Yamamoto, Ph ys. Rev. C 73 (2006), 044008; Th. A. Rijken and Y. Yamamoto, nucl-th/0608074]. For the soft-core one-boson-exchange (OBE) models we refer to the literature [Th. A. Rijken, in Proceedings of the International Conference on Few-Body Problems in Nuclear and Particle Physics, Quebec, 1974, ed. R. J. Slobodrian, B. Cuec and R. Ramavataram (Presses Universitè Laval, Quebec, 1975), p. 136; Th. A. Rijken, Ph. D. thesis, University of Nijmegen, 1975; M. M. Nagels, Th. A. Rijken and J. J. de Swart, Phys. Rev. D 17 (1978), 768; P. M. M. Maessen, Th. A. Rijken and J. J. de Swart, Phys. Rev. C 40 (1989), 2226; Th. A. Rijken, V. G. J. Stoks and Y. Yamamoto, Phys. Rev. C 59 (1999), 21; V. G. J. Stoks and Th. A. Rijken, Phys. Rev. C 59 (1999), 3009]. All ingredients of these latter models are also part of ESC08, and so a description of ESC08 comprises all models so far in principle. The extended-soft-core (ESC) interactions consist of local- and non-local-potentials due to (i) one-boson-exchanges (OBE), which are the members of nonets of

  13. Innovative hyperspectral imaging (HSI) based techniques applied to end-of-life concrete drill core characterization for optimal dismantling and materials recovery

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Picone, Nicoletta; Serranti, Silvia

    2015-02-01

    The reduction of EOL concrete disposal in landfills, together with a lower exploitation of primary raw materials, generates a strong interest to develop, set-up and apply innovative technologies to maximize Construction and Demolition Waste (C&DW) conversion into useful secondary raw materials. Such a goal can be reached starting from a punctual in-situ efficient characterization of the objects to dismantle in order to develop demolition actions aimed to set up innovative mechanical-physical processes to recover the different materials and products to recycle. In this paper an innovative recycling-oriented characterization strategy based on HyperSpectral Imaging (HSI) is described in order to identify aggregates and mortar in drill core samples from end-of-life concrete. To reach this goal, concrete drill cores from a demolition site were systematically investigated by HSI in the short wave infrared field (1000-2500 nm). Results obtained by the adoption of the HSI approach showed as this technology can be successfully applied to analyze quality and characteristics of C&DW before dismantling and as final product to reutilise after demolition-milling-classification actions. The proposed technique and the related recognition logics, through the spectral signature detection of finite physical domains (i.e. concrete slice and/or particle) of different nature and composition, allows; i) to develop characterization procedures able to quantitatively assess end-of-life concrete compositional/textural characteristics and ii) to set up innovative sorting strategies to qualify the different materials constituting drill core samples.

  14. Antivirals interacting with hepatitis B virus core protein and core mutations may misdirect capsid assembly in a similar fashion.

    PubMed

    Hacker, Hans Jörg; Deres, Karl; Mildenberger, Maria; Schröder, Claus H

    2003-12-15

    Recently, heteroarylpyrimidines (HAP) have been identified as potent inhibitors of capsid maturation. Here we discuss the HAP mode of action comparing the aggregation phenotype of wild-type and mutant core proteins with the respective phenotype imposed by HAP or other agents interacting with core protein. Pertinent tests include core fusion protein-mediated transactivation in a two-hybrid system and capsid formation. The finding that transactivation appeared to be unaffected by HAP, or by mutations preventing assembly, is surprising and raises the question for the structure of the interacting hybrid core proteins: Are they monomers, dimers or even oligomers? A direct activity of core fusion monomers is not excluded but considered to be highly unlikely due to rapid homodimerisation. A role of core fusion dimers in transactivation would indicate distinct interactions with a differential sensitivity to HAP. Regarding significance of data gained in two-hybrid systems, caution is necessary, since the site of transactivation is the nucleus, whereas the real site of the core protein interactions during replication is the cytoplasm. Apparently, HAP leave the monomer-monomer interface of HBV core protein unaffected but prevent capsid maturation by interacting with a region known to be crucial for dimer multimerisation and formation of stable capsids. It is suggested to use antivirals as tools for the elucidation of early steps in genome replication and capsid assembly. A frame for this could be the hypothesis that the virus uses soluble core protein, namely intracellular maturation intermediates of HbeAg for a core targeted self-restriction of replication. PMID:14637185

  15. Lunar Power Dissipated by Tides and Core-Mantle Interaction

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.; Yoder, C. F.; Dickey, J. O.

    2000-01-01

    Analysis of Lunar Laser Ranges gives information on lunar tidal dissipation and a molten core. For the ancient moon tidal heating of the interior and heating at the core-mantle boundary could have rivaled radiogenic heating.

  16. Resonant-spin-ordering of vortex cores in interacting mesomagnets

    NASA Astrophysics Data System (ADS)

    Jain, Shikha

    2013-03-01

    The magnetic system of interacting vortex-state elements have a dynamically reconfigurable ground state characterized by different relative polarities and chiralities of the individual disks; and have a corresponding dynamically controlled spectrum of collective excitation modes that determine the microwave absorption of the crystal. The development of effective methods for dynamic control of the ground state in this vortex-type magnonic crystal is of interest both from fundamental and technological viewpoints. Control of vortex chirality has been demonstrated previously using various techniques; however, control and manipulation of vortex polarities remain challenging. In this work, we present a robust and efficient way of selecting the ground state configuration of interacting magnetic elements using resonant-spin-ordering approach. This is achieved by driving the system from the linear regime of constant vortex gyrations to the non-linear regime of vortex-core reversals at a fixed excitation frequency of one of the coupled modes. Subsequently reducing the excitation field to the linear regime stabilizes the system to a polarity combination whose resonant frequency is decoupled from the initialization frequency. We have utilized the resonant approach to transition between the two polarity combinations (parallel or antiparallel) in a model system of connected dot-pairs which may form the building blocks of vortex-based magnonic crystals. Taking a step further, we have extended the technique by studying many-particle system for its potential as spin-torque oscillators or logic devices. Work at Argonne was supported by the U. S. DOE, Office of BES, under Contract No. DE-AC02-06CH11357. This work was in part supported by grant DMR-1015175 from the U. S. National Science Foundation, by a Contract from the U.S. Army TARDEC and RDECOM.

  17. Intermediate-scale tests of sodium interactions with calcite and dolomite aggregate concretes. [LMFBR

    SciTech Connect

    Randich, E.; Acton, R.U.

    1983-09-01

    Two intermediate-scale tests were performed to compare the behavior of calcite and dolomite aggregate concretes when attacked by molten sodium. The tests were performed as part of an interlaboratory comparison between Sandia National Laboratories and Hanford Engineering Development Laboratories. Results of the tests at Sandia National Laboratories are reported here. The results show that both concretes exhibit similar exothermic reactions with molten sodium. The large difference in reaction vigor suggested by thermodynamic considerations of CO/sub 2/ release from calcite and dolomite was not realized. Penetration rates of 1.4 to 1.7 mm/min were observed for short periods of time with reaction zone temperatures in excess of 800/sup 0/C during the energetic attack. The penetration was not uniform over the entire sodium-concrete contact area. Rapid attack may be localized due to inhomogeneities in the concrete. The chemical reaction zone is less then one cm thick for the calcite concrete but is about seven cm thick for the dolomite concrete.

  18. High performance multi-core iron oxide nanoparticles for magnetic hyperthermia: microwave synthesis, and the role of core-to-core interactions

    NASA Astrophysics Data System (ADS)

    Blanco-Andujar, C.; Ortega, D.; Southern, P.; PankhurstJoint Last Authors., Q. A.; Thanh, N. T. K.

    2015-01-01

    The adoption of magnetic hyperthermia as either a stand-alone or adjunct therapy for cancer is still far from being optimised due to the variable performance found in many iron oxide nanoparticle systems, including commercially available formulations. Herein, we present a reproducible and potentially scalable microwave-based method to make stable citric acid coated multi-core iron oxide nanoparticles, with exceptional magnetic heating parameters, viz. intrinsic loss parameters (ILPs) of up to 4.1 nH m2 kg-1, 35% better than the best commercial equivalents. We also probe the core-to-core magnetic interactions in the particles via remanence-derived Henkel and ΔM plots. These reveal a monotonic dependence of the ILP on the magnetic interaction field Hint, and show that the interactions are demagnetising in nature, and act to hinder the magnetic heating mechanism.The adoption of magnetic hyperthermia as either a stand-alone or adjunct therapy for cancer is still far from being optimised due to the variable performance found in many iron oxide nanoparticle systems, including commercially available formulations. Herein, we present a reproducible and potentially scalable microwave-based method to make stable citric acid coated multi-core iron oxide nanoparticles, with exceptional magnetic heating parameters, viz. intrinsic loss parameters (ILPs) of up to 4.1 nH m2 kg-1, 35% better than the best commercial equivalents. We also probe the core-to-core magnetic interactions in the particles via remanence-derived Henkel and ΔM plots. These reveal a monotonic dependence of the ILP on the magnetic interaction field Hint, and show that the interactions are demagnetising in nature, and act to hinder the magnetic heating mechanism. Electronic supplementary information (ESI) available: Reproducibility studies and additional characterisation data including SQUID Magnetometry, TEM, ATR-FTIR, XRD and Mossbauer spectroscopy. See DOI: 10.1039/c4nr06239f

  19. How Concrete Is Concrete?

    ERIC Educational Resources Information Center

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  20. Conceptual model analysis of interaction at a concrete-Boom Clay interface

    NASA Astrophysics Data System (ADS)

    Liu, Sanheng; Jacques, Diederik; Govaerts, Joan; Wang, Lian

    In many concepts for deep disposal of high-level radioactive waste, cementitious materials are used in the engineered barriers. For example, in Belgium the engineered barrier system is based on a considerable amount of cementitious materials as buffer and backfill in the so-called supercontainer embedded in the hosting geological formation. A potential hosting formation is Boom Clay. Insight in the interaction between the high-pH pore water of the cementitious materials and neutral-pH Boom Clay pore water is required. Two problems are quite common for modeling of such a system. The first one is the computational cost due to the long timescale model assessments envisaged for the deep disposal system. Also a very fine grid (in sub-millimeter), especially at interfaces has to be used in order to accurately predict the evolution of the system. The second one is whether to use equilibrium or kinetic reaction models. The objectives of this paper are twofold. First, we develop an efficient coupled reactive transport code for this diffusion-dominated system by making full use of multi-processors/cores computers. Second, we investigate how sensitive the system is to chemical reaction models especially when pore clogging due to mineral precipitation is considered within the cementitious system. To do this, we selected two portlandite dissolution models, i.e., equilibrium (fastest) and diffusion-controlled model with precipitation of a calcite layer around portlandite particles (diffusion-controlled dissolution). The results show that with shrinking core model portlandite dissolution and calcite precipitation are much slower than with the equilibrium model. Also diffusion-controlled dissolution smooths out dissolution fronts compared to the equilibrium model. However, only a slight difference with respect to the clogging time can be found even though we use a very small diffusion coefficient (10-20 m2/s) in the precipitated calcite layer.

  1. Interactions of aqueous Cu2+, Zn2+ and Pb2+ ions with crushed concrete fines.

    PubMed

    Coleman, Nichola J; Lee, William E; Slipper, Ian J

    2005-05-20

    The crushing of reclaimed concrete-based demolition waste to produce recycled aggregate gives rise to a large volume of cement-rich fine material for which market development would be beneficial. It was envisaged that this fine fraction may prove to be an effective sorbent for aqueous heavy metal species by virtue of its ion exchangeable phases and high pH. A batch sorption study confirmed that crushed concrete, in the particle size range 1-2 mm, successfully excluded Cu2+ (35 mg g(-1)), Zn2+ (33 mg g(-1)) and Pb2+ (37 mg g(-1)) from aqueous media. Subsequent distilled water leaching of the metal-laden concrete particles indicated that 1.9, 0.9 and 0.2% of the bound metals, Cu2+, Zn2+ and Pb2+, respectively, were readily soluble. Scanning electron microscopy revealed that the removal of Cu2+ and Zn2+ arose from surface precipitation reactions, whereas, the principal mechanism of uptake of Pb2+ was found to be by diffusion into the cement matrix. The metal ion removal efficiency of crushed concrete fines is compared with those of other low cost sorbents and potential applications which may exploit this sorptive property are also discussed. PMID:15885423

  2. Interaction of sigma 70 with Escherichia coli RNA polymerase core enzyme studied by surface plasmon resonance.

    PubMed

    Ferguson, A L; Hughes, A D; Tufail, U; Baumann, C G; Scott, D J; Hoggett, J G

    2000-09-22

    The interaction between the core form of bacterial RNA polymerases and sigma factors is essential for specific promoter recognition, and for coordinating the expression of different sets of genes in response to varying cellular needs. The interaction between Escherichia coli core RNA polymerase and sigma 70 has been investigated by surface plasmon resonance. The His-tagged form of sigma 70 factor was immobilised on a Ni2+-NTA chip for monitoring its interaction with core polymerase. The binding constant for the interaction was found to be 1.9x10(-7) M, and the dissociation rate constant for release of sigma from core, in the absence of DNA or transcription, was 4x10(-3) s(-1), corresponding to a half-life of about 200 s. PMID:11007979

  3. Density Anomalies in the Mantle and the Gravitational Core-Mantle Interaction

    NASA Technical Reports Server (NTRS)

    Kuang, Weijia; Liu, Lanbo

    2003-01-01

    Seismic studies suggest that the bulk of the mantle is heterogeneous, with density variations in depth as well as in horizontal directions (latitude and longitude). This density variation produces a three- dimensional gravity field throughout the Earth. On the other hand, the core density also varies in both time and space, due to convective core flow. Consequently, the fluid outer core and the solid mantle interact gravitationally due to the mass anomalies in both regions. This gravitational core-mantle interaction could play a significant role in exchange of angular momentum between the core and the mantle, and thus the change in Earth's rotation on time scales of decades and longer. Aiming at estimating the significance of the gravitational core-mantle interaction on Earth's rotation variation, we introduce in our MoSST core dynamics model a heterogeneous mantle, with a density distribution derived from seismic results. In this model, the core convection is driven by the buoyancy forces. And the density variation is determined dynamically with the convection. Numerical simulation is carried out with different parameter values, intending to extrapolate numerical results for geophysical implications.

  4. Mineralogical characterization of the Tournemire argillite after in situ interaction with concretes.

    PubMed

    Tinseau, E; Bartier, D; Hassouta, L; Devol-Brown, I; Stammose, D

    2006-01-01

    This study aims to investigate, through mineralogical characterization (SEM, XRD) and mass-balance calculations, the effects of contact time, concrete types and presence of free water on the Tournemire argillite under in situ conditions. Three sampling zones from Excavation Disturbed Zone (EDZ) areas have been chosen: (1) dry contacts, collected at the tunnel masonry/argillite interface (contact time - 125 years), (2) wet contacts, taken close to drained areas below the tunnel roadbed in contact with the canal draining the Cernon fault water (contact time - 15 and 7 years) and at the tunnel masonry/argillite interface over 70 m from the Cernon fault (contact time - 125 years). This study shows that: in the absence of water, no significant modification of argillite is observed after 125 years, except for pyrite dissolution and gypsum precipitation; in the presence of water, precipitation of gypsum, recrystallization of mixed-layer clays, neoformation of zeolites and K-feldspars overgrowths are observed. At the concrete/argillite interface near the Cernon fault, important dolomite neoformation and leaching of chlorite and kaolinite occur. These processes are enhanced with contact time, low flow rate and the nature of the concrete (compound cement Portland CEM II 32.5). Evidence for oxidation processes linked to the EDZ (pyrite oxidation, Fe-oxy-hydroxide and gypsum precipitation) is observed. PMID:16600584

  5. Influence of reaction kinetics and mesh refinement on the numerical modelling of concrete/clay interactions

    NASA Astrophysics Data System (ADS)

    Marty, Nicolas C. M.; Tournassat, Christophe; Burnol, André; Giffaut, Eric; Gaucher, Eric C.

    2009-01-01

    SummaryLarge quantities of cements and concretes need to be incorporated in geological disposal facilities for long-lived radwaste. An alkaline plume diffusing from an aged concrete (pH ˜ 12.5) through argillite-type rocks has been modelled considering feedback of porosity value variations on transport properties using the reactive transport code TOUGHREACT. The mineralogical composition of the argillite is modified at the interface with the concrete. Diffusion of cementitious elements leads to rapid and strong porosity occlusion in the argillite. Numerical results show that both reaction rates and spatial refinement affect mineralogical transformation pathways. The variations in porosity and the extension of the zone affected by the alkaline perturbation are compared at different times. The major effects of mineral precipitation under kinetic constraints, rather than local equilibrium, are a delay in the porosity clogging and an increase in the extension of the alkaline perturbation in the clay formation. The same time-delay rise for the porosity occlusion also appears for the roughest spatial resolutions. A simulation as representative as possible of temporal and spatial scales of cementation processes must then be supported by more comparative data such as long term experimental investigations or natural analogues.

  6. Time-resolved SANS studies on block copolymer micelles with varying core-solvent interactions

    NASA Astrophysics Data System (ADS)

    Cooksey, Tyler; Singh, Avantika; Marquez, Maria; Robertson, Megan

    The self-assembly of block copolymer micelles occurs through a relaxation process dominated by the exchange of individual polymer chains. The objective of this work is to probe the single chain exchange of block copolymer micelles with varying core-solvent interactions, utilizing time-resolved neutron scattering (TR-SANS). The interactions between the core-forming polymer and the solvent has many implications for the micelle structure, including the aggregation number, micelle size, and interfacial tension. However, few studies have investigated the effect of the core polymer-solvent interactions on the dynamics of micelle formation. We will focus our study on poly(epsilon-caprolactone-block-ethylene oxide) block copolymers forming micelle structures in mixtures of water and tetrahydrofuran (THF). It was observed that changing the THF concentration, which varies the degree of repulsion between the core and solvent, greatly influences the single chain exchange rate in this system.

  7. Production of high strength concrete

    SciTech Connect

    Peterman, M.B.; Carrasquillo, R.L.

    1986-01-01

    The criteria for selection of concrete materials and their proportions to producer uniform, economical, high strength concrete are presented in this book. The recommendations provided are based on a study of the interactions among components of plain concrete and mix proportions, and of their contribution to the compressive strength of high strength concrete. These recommendations will serve as guidelines to practicing engineers, in the selection of materials and their proportions for the production of high strength concrete. Increasing demands for improved efficiency and reduced construction costs have resulted in engineers beginning to design large structures using higher strength concrete at higher stress levels. There are definite advantages, both technical and economical, in using high strength concrete. For example, for a given cross section, prestresses concrete bridge girders can carry greater service loads across longer spans if made using high strength concrete. In addition, cost comparisons have shown that the savings obtained are significantly greater than the added cost of the higher quality concrete.

  8. Fluid-rock interactions between xanthan-chromium(III) gel systems and dolomite core material

    SciTech Connect

    McCool, C.S.; Green, D.W.; Willhite, G.P.

    1995-11-01

    Gelation of chromium(III)-xanthan systems in dolomite core material was investigated. Compositional changes in the gelant caused by interactions with the dolomite core material resulted in low permeability reductions for gelants prepared with chromium chloride, chromium acetate and a chromium diamine salt. The primary cause of incomplete gelation in the dolomite material was the increase in gelant pH that resulted in precipitation of chromium.

  9. Water-Rock Interaction Simulations of Iron Oxide Mobilization and Precipitation: Implications of Cross-diffusion Reactions for Terrestrial and Mars 'Blueberry' Hematite Concretions

    NASA Astrophysics Data System (ADS)

    Park, A. J.; Chan, M. A.; Parry, W. T.

    2005-12-01

    Modeling of how terrestrial concretions form can provide valuable insights into understanding water-rock interactions that led to the formation of hematite concretions at Meridiani Planum, Mars. Numerical simulations of iron oxide concretions in the Jurassic Navajo Sandstone of southern Utah provide physical and chemical input parameters for emulating conditions that may have prevailed on Mars. In the terrestrial example, iron oxide coatings on eolian sand grains are reduced and mobilized by methane or petroleum. Precipitation of goethite or hematite occurs as Fe interacts with oxygen. Conditions that produced Navajo Sandstone concretions can range from a regional scale that is strongly affected by advection of large pore volumes of water, to small sub-meter scale features that are dominantly controlled by diffusive processes. Hematite concretions are results of a small-scale cross-diffusional process, where Fe and oxygen are supplied from two opposite sides from the 'middle' zone of mixing where concretions precipitate. This is an ideal natural system where Liesegang banding and other self-organized patterns can evolve. A complicating variable here is the sedimentologic (both mineralogic and textural) heterogeneity that, in reality, may be the key factor controlling the nucleation and precipitation habits (including possible competitive growth) of hematite concretions. Sym.8 water-rock interaction simulator program was used for the Navajo Sandstone concretions. Sym.8 is a water-rock simulator that accounts for advective and diffusive mass-transfer, and equilibrium and kinetic reactions. The program uses a dynamic composite media texture model to address changing sediment composition and texture to be consistent with the reaction progress. Initial one-dimensional simulation results indicate precipitation heterogeneity in the range of sub-meters, e.g., possible banding and distribution of iron oxide nodules may be centimeters apart for published diffusivities and

  10. A Study on Interaction Between Aptitudes and Concrete vs. Symbolic Teaching Methods as Presented to Third-Grade Students in Multiplication and Division.

    ERIC Educational Resources Information Center

    Trask, Marvin Wellington

    The interaction between aptitudes and concrete vs. symbolic teaching methods was investigated. One class of randomly selected third graders was taught multiplication and division by a symbolic method while a second class was given a manipulative approach. Each student took the Stanford Achievement Test battery, the Otis-Lennon Mental Ability Test,…

  11. Laboratory Study of Crack Development and Crack Interaction in Concrete Blocks due to Swelling of Cracking Agent

    NASA Astrophysics Data System (ADS)

    Frühwirt, Thomas; Plößer, Arne; Konietzky, Heinz

    2015-04-01

    The main focus of this work was to investigate temporary and spatial features of crack development in concrete blocks due to the action of a swelling agent. A commercial available cement-based mortar which shows heavily swelling behaviour when hydrating is used to provide inside pressure in boreholes in conrete blocks and hence serves as cracking agent. As no data for the swelling behaviour of the cracking agent were available the maximum axial swelling stress and axial free swelling strain were determined experimentally. In a first series of tests on concrete blocks the influence of an external mechanical, unidirectional stress on the development-time and orientation of cracks has been investigated for a range of loading levels. The stress state in the blocks prepared with a single borehole was determined by a superposition of internal stresses caused by swelling pressure and external mechanical loading. For a second series of tests prismatic blocks with two boreholes where prepared. This test setup allowed to realize different orientation of boreholes with respect to the uniaxial loading direction. Complementary tests were done using the cracking agent in both, only one or none of the boreholes. Different modes of crack interaction and influence of filled or unfilled boreholes have been observed. Features of crack development showed significant sensitivity to external loading. Starting even at very low load levels crack orientation was primarely determined by the direction of the external load. Temporal change in crack development due to the different load levels was insignificant and no consistent conclusion could be drawn. Crack interaction phenomena only were observed with two boreholes orientated primarely in direction of the external loading. Even in these cases crack orientation was mainly determined by the external stress field and only locally influenced by other cracks or the unfilled borehole. The work provides us with an extensive catalogue of

  12. Structural requirements for assembly and homotypic interactions of the hepatitis C virus core protein.

    PubMed

    Kim, Meehyein; Ha, Youngju; Park, Hae-Joon

    2006-12-01

    The hepatitis C virus (HCV) core protein is involved in the assembly of nucleocapsid particles, as well as regulation of cellular and viral gene expression. To investigate the biological properties of the viral core protein and viral RNA assembly, two recombinant core proteins, the mature core protein (named C179) and a C-terminal truncated protein (named C124), were expressed and purified. To confirm their ability to generate viral particles, the production of nucleocapsid-like particles was monitored using transmission electron microscopy (EM). The EM analysis revealed that exposure of these proteins to the 5' untranslated region (5' UTR) of the viral RNA resulted in generation of spherical particles of 30-140nm in diameter. Interestingly, a cross-linking analysis revealed that C124 required an RNA component for homotypic interactions. In contrast, C179 successfully assembled in the absence of nucleic acids. Additionally, RNA-mediated conversion of the C124 structure into a more stable state was maintained even after RNase treatment. Therefore, our results indicate that the basic N-terminal domain of the viral core protein utilizes RNA components to induce conformational changes or efficient homotypic interactions, while the C-terminal domain may contain key peptide sequences for initiating spontaneous multimerization at the early stages of viral assembly. PMID:16949699

  13. Plasma-wall interaction data needs critical to a Burning Core Experiment (BCX)

    SciTech Connect

    Not Available

    1985-11-01

    The Division of Development and Technology has sponsored a four day US-Japan workshop ''Plasma-Wall Interaction Data Needs Critical to a Burning Core Experiment (BCX)'', held at Sandia National Laboratories, Livermore, California on June 24 to 27, 1985. The workshop, which brought together fifty scientists and engineers from the United States, Japan, Germany, and Canada, considered the plasma-material interaction and high heat flux (PMI/HHF) issues for the next generation of magnetic fusion energy devices, the Burning Core Experiment (BCX). Materials options were ranked, and a strategy for future PMI/HHF research was formulated. The foundation for international collaboration and coordination of this research was also established. This volume contains the last three of the five technical sessions. The first of the three is on plasma materials interaction issues, the second is on research facilities and the third is from smaller working group meetings on graphite, beryllium, advanced materials and future collaborations.

  14. Interaction of structural core protein of Classical Swine Fever Virus with endoplasmic reticulum-associated degradation pathway protein OS9

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classical Swine Fever Virus (CSFV) Core protein is involved in virus RNA protection, transcription regulation and virus virulence. To discover additional Core protein functions a yeast two-hybrid system was used to identify host proteins that interact with Core. Among the identified host proteins, t...

  15. Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary

    NASA Astrophysics Data System (ADS)

    Elbert, Oliver D.; Bullock, James S.; Garrison-Kimmel, Shea; Rocha, Miguel; Oñorbe, Jose; Peter, Annika H. G.

    2015-10-01

    We investigate the effect of self-interacting dark matter (SIDM) on the density profiles of Vmax ≃ 40km s-1 isolated dwarf dark matter haloes - the scale of relevance for the too big to fail problem (TBTF) - using very high resolution cosmological zoom simulations. Each halo has millions of particles within its virial radius. We find that SIDM models with cross-sections per unit mass spanning the range σ/m = 0.5-50 cm2 g-1 alleviate TBTF and produce constant-density cores of size 300-1000 pc, comparable to the half-light radii of M⋆ ˜ 105 - 7 M⊙ dwarfs. The largest, lowest density cores develop for cross-sections in the middle of this range, σ/m ˜ 5-10 cm2 g-1. Our largest SIDM cross-section run (σ/m = 50 cm2 g-1) develops a slightly denser core owing to mild core-collapse behaviour, but it remains less dense than the cold dark matter case and retains a constant-density core profile. Our work suggests that SIDM cross-sections as large or larger than 50 cm2 g-1 remain viable on velocity scales of dwarf galaxies (vrms ˜ 40 km s-1). The range of SIDM cross-sections that alleviate TBTF and the cusp/core problem spans at least two orders of magnitude and therefore need not be particularly fine-tuned.

  16. Effect on vehicle and track interaction of installation faults in the concrete bearing surface of a direct-fixation track

    NASA Astrophysics Data System (ADS)

    Yang, S. C.; Kim, E.

    2012-01-01

    Various installation faults can occur in fasteners in the construction of a direct-fixation track using the top-down method. In extreme cases, these faults may cause excessive interaction between the train and track, compromise the running safety of the train, and cause damage to the track components. Therefore, these faults need to be kept within the allowable level through an investigation of their effects on the interactions between the train and track. In this study, the vertical dynamic stiffness of fasteners in installation faults was measured based on a dynamic stiffness test by means of an experimental apparatus that was devised to feasibly reproduce installation faults with an arbitrary shape. This study proposes an effective analytical model for a train-track interaction system in which most elements, except the nonlinear wheel-rail contact and some components that behave bilinearly, exhibit linear behavior. To investigate the effect of the behavior of fasteners in installation faults in a direct-fixation track on the vehicle and track, vehicle-track interaction analyses were carried out, targeting key review parameters such as the wheel load reduction factor, vertical rail displacement, wheel load, and mean stress of the elastomer. From the results, it was noted that it is more important for the installation faults in the concrete bearing surface of a direct-fixation track to be limited for the sake of the long-term durability of the elastomer rather than for the running safety of the train or the structural safety of the track.

  17. An investigation of ab initio shell-model interactions derived by no-core shell model

    NASA Astrophysics Data System (ADS)

    Wang, XiaoBao; Dong, GuoXiang; Li, QingFeng; Shen, CaiWan; Yu, ShaoYing

    2016-09-01

    The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory (MBPT), the first work of which can be traced to Brown and Kuo's first attempt in 1966, derived from the Hamada-Johnston nucleon-nucleon potential. However, the convergence of the MBPT is still unclear. On the other hand, ab initio theories, such as Green's function Monte Carlo (GFMC), no-core shell model (NCSM), and coupled-cluster theory with single and double excitations (CCSD), have made many progress in recent years. However, due to the increasing demanding of computing resources, these ab initio applications are usually limited to nuclei with mass up to A = 16. Recently, people have realized the ab initio construction of valence-space effective interactions, which is obtained through a second-time renormalization, or to be more exactly, projecting the full-manybody Hamiltonian into core, one-body, and two-body cluster parts. In this paper, we present the investigation of such ab initio shell-model interactions, by the recent derived sd-shell effective interactions based on effective J-matrix Inverse Scattering Potential (JISP) and chiral effective-field theory (EFT) through NCSM. In this work, we have seen the similarity between the ab initio shellmodel interactions and the interactions obtained by MBPT or by empirical fitting. Without the inclusion of three-body (3-bd) force, the ab initio shell-model interactions still share similar defects with the microscopic interactions by MBPT, i.e., T = 1 channel is more attractive while T = 0 channel is more repulsive than empirical interactions. The progress to include more many-body correlations and 3-bd force is still badly needed, to see whether such efforts of ab initio shell-model interactions can reach similar precision as the interactions fitted to experimental data.

  18. Core-shell interaction and its impact on the optical absorption of pure and doped core-shell CdSe/ZnSe nanoclusters

    NASA Astrophysics Data System (ADS)

    Wang, Xinqin; Cui, Yingqi; Yu, Shengping; Zeng, Qun; Yang, Mingli

    2016-04-01

    The structural, electronic, and optical properties of core-shell nanoclusters, (CdSe)x@(CdSe)y and their Zn-substituted complexes of x = 2-4 and y = 16-28, were studied with density functional theory calculations. The substitution was applied in the cores, the shells, and/or the whole clusters. All these clusters are characterized by their core-shell structures in which the core-shell interaction was found different from those in core or in shell, as reflected by their bondlengths, volumes, and binding energies. Moreover, the core and shell combine together to compose a new cluster with electronic and optical properties different from those of separated individuals, as reflected by their HOMO-LUMO gaps and optical absorptions. With the substitution of Cd by Zn, the structural, electronic, and optical properties of clusters change regularly. The binding energy increases with Zn content, attributed to the strong Zn-Se bonding. For the same core/shell, the structure with a CdSe shell/core has a narrower gap than that with a ZnSe shell/core. The optical absorption spectra also change accordingly with Zn substitution. The peaks blueshift with increasing Zn concentration, accompanying with shape variations in case large number of Cd atoms are substituted. Our calculations reveal the core-shell interaction and its influence on the electronic and optical properties of the core-shell clusters, suggesting a composition-structure-property relationship for the design of core-shell CdSe and ZnSe nanoclusters.

  19. Interactive Learning with Java Applets: Using Interactive, Web-Based Java Applets to Present Science in a Concrete, Meaningful Manner

    ERIC Educational Resources Information Center

    Corder, Greg

    2005-01-01

    Science teachers face challenges that affect the quality of instruction. Tight budgets, limited resources, school schedules, and other obstacles limit students' opportunities to experience science that is visual and interactive. Incorporating web-based Java applets into science instruction offers a practical solution to these challenges. The…

  20. Interaction of the core fragments of the LL-37 host defense peptide with actin

    PubMed Central

    Sol, Asaf; Wang, Guangshun; Blotnick, Edna; Golla, Radha; Muhlrad, Andras

    2015-01-01

    Host defense peptides are effector molecules of the innate immunity that possess antimicrobial and health-promoting properties. Due to their potential therapeutic activities, host defense peptides are being explored as alternatives for antibiotics. The human LL-37 and its shorter, cost-effective, bactericidal core peptide derivates have been suggested for their therapeutic potential. Bacteria evade host defense peptides by proteolytic inactivation. Actin released from necrotized cells and abundant in infected sites was shown to bind and protect LL-37 from microbial proteolytic degradation, and to enable the peptide’s antimicrobial action despite the presence of the proteases. Here, we characterized the interactions of the 10–13 residues long LL-37 core peptides with actin. We show that the LL-37 core peptides associate with actin with a lower affinity than that of LL-37. Their association with actin, which is very ionic strength sensitive, is mainly based on electrostatic interactions. Likewise, the antimicrobial activity against Escherichia coli of the minimal antimicrobial peptide KR-12 but not FK-13 nor LL-37 is also very sensitive to salts. In addition, the antimicrobial activity of the FK-13 core peptide is protected by actin against the tested bacterial proteases in a similar manner to that of LL-37, supporting its potential for therapeutic use. PMID:26726303

  1. Core-Shell Microgels with Switchable Elasticity at Constant Interfacial Interaction.

    PubMed

    Seuss, Maximilian; Schmolke, Willi; Drechsler, Astrid; Fery, Andreas; Seiffert, Sebastian

    2016-06-29

    Hydrogels based on poly(N-isopropylacrylamide) (pNIPAAm) exhibit a thermo-reversible volume phase transition from swollen to deswollen states. This change of the hydrogel volume is accompanied by changes of the hydrogel elastic and Young's moduli and of the hydrogel interfacial interactions. To decouple these parameters from one another, we present a class of submillimeter sized hydrogel particles that consist of a thermosensitive pNIPAAm core wrapped by a nonthermosensitive polyacrylamide (pAAm) shell, each templated by droplet-based microfluidics. When the microgel core deswells upon increase of the temperature to above 34 °C, the shell is stretched and dragged to follow this deswelling into the microgel interior, resulting in an increase of the microgel surficial Young's modulus. However, as the surface interactions of the pAAm shell are independent of temperature at around 34 °C, they do not considerably change during the pNIPAAm-core volume phase transition. This feature makes these core-shell microgels a promising platform to be used as building blocks to assemble soft materials with rationally and independently tunable mechanics. PMID:27276500

  2. Star Formation and Feedback: A Molecular Outflow–Prestellar Core Interaction in L1689N

    NASA Astrophysics Data System (ADS)

    Lis, D. C.; Wootten, H. A.; Gerin, M.; Pagani, L.; Roueff, E.; van der Tak, F. F. S.; Vastel, C.; Walmsley, C. M.

    2016-08-01

    We present Herschel,11 ALMA Compact Array (ACA), and Caltech Submillimeter Observatory observations of the prestellar core in L1689N, which has been suggested to be interacting with a molecular outflow driven by the nearby solar-type protostar IRAS 16293-2422. This source is characterized by some of the highest deuteration levels observed in the interstellar medium. The change in the NH2D line velocity and width across the core provides clear evidence of an interaction with the outflow, traced by the high-velocity water emission. Quiescent, cold gas characterized by narrow line widths is seen in the NE part of the core, while broader, more disturbed line profiles are seen in the W/SW part. Strong N2D+ and ND3 emission is detected with ACA extending S/SW from the peak of the single-dish NH2D emission. The ACA data also reveal the presence a compact dust continuum source with a mean size of ∼1100 au, a central density of (1–2) × 107 cm‑3, and a mass of 0.2–0.4 M ⊙. The dust emission peak is displaced ∼5″ to the south with respect to the N2D+ and ND3 emission, as well as the single-dish dust continuum peak, suggesting that the northern, quiescent part of the core is characterized by spatially extended continuum emission, which is resolved out by the interferometer. We see no clear evidence of fragmentation in this quiescent part of the core, which could lead to a second generation of star formation, although a weak dust continuum source is detected in this region in the ACA data.

  3. Star Formation and Feedback: A Molecular Outflow–Prestellar Core Interaction in L1689N

    NASA Astrophysics Data System (ADS)

    Lis, D. C.; Wootten, H. A.; Gerin, M.; Pagani, L.; Roueff, E.; van der Tak, F. F. S.; Vastel, C.; Walmsley, C. M.

    2016-08-01

    We present Herschel,11 ALMA Compact Array (ACA), and Caltech Submillimeter Observatory observations of the prestellar core in L1689N, which has been suggested to be interacting with a molecular outflow driven by the nearby solar-type protostar IRAS 16293-2422. This source is characterized by some of the highest deuteration levels observed in the interstellar medium. The change in the NH2D line velocity and width across the core provides clear evidence of an interaction with the outflow, traced by the high-velocity water emission. Quiescent, cold gas characterized by narrow line widths is seen in the NE part of the core, while broader, more disturbed line profiles are seen in the W/SW part. Strong N2D+ and ND3 emission is detected with ACA extending S/SW from the peak of the single-dish NH2D emission. The ACA data also reveal the presence a compact dust continuum source with a mean size of ˜1100 au, a central density of (1–2) × 107 cm‑3, and a mass of 0.2–0.4 M ⊙. The dust emission peak is displaced ˜5″ to the south with respect to the N2D+ and ND3 emission, as well as the single-dish dust continuum peak, suggesting that the northern, quiescent part of the core is characterized by spatially extended continuum emission, which is resolved out by the interferometer. We see no clear evidence of fragmentation in this quiescent part of the core, which could lead to a second generation of star formation, although a weak dust continuum source is detected in this region in the ACA data.

  4. Identifying a Core RNA Polymerase Surface Critical for Interactions with a Sigma-Like Specificity Factor

    PubMed Central

    Cliften, Paul F.; Jang, Sei-Heon; Jaehning, Judith A.

    2000-01-01

    Cyclic interactions occurring between a core RNA polymerase (RNAP) and its initiation factors are critical for transcription initiation, but little is known about subunit interaction. In this work we have identified regions of the single-subunit yeast mitochondrial RNAP (Rpo41p) important for interaction with its sigma-like specificity factor (Mtf1p). Previously we found that the whole folded structure of both polypeptides as well as specific amino acids in at least three regions of Mtf1p are required for interaction. In this work we started with an interaction-defective point mutant in Mtf1p (V135A) and used a two-hybrid selection to isolate suppressing mutations in the core polymerase. We identified suppressors in three separate regions of the RNAP which, when modeled on the structure of the closely related phage T7 RNAP, appear to lie on one surface of the protein. Additional point mutations and biochemical assays were used to confirm the importance of each region for Rpo41p-Mtf1p interactions. Remarkably, two of the three suppressors are found in regions required by T7 RNAP for DNA sequence recognition and promoter melting. Although these essential regions of the phage RNAP are poorly conserved with the mitochondrial RNAPs, they are conserved among the mitochondrial enzymes. The organellar RNAPs appear to use this surface in an alternative way for interactions with their separate sigma-like specificity factor, which, like its bacterial counterpart, provides promoter recognition and DNA melting functions to the holoenzyme. PMID:10958696

  5. Physico-chemical interactions at the concrete-bitumen interface of nuclear waste repositories

    NASA Astrophysics Data System (ADS)

    Bertron, A.; Ranaivomanana, H.; Jacquemet, N.; Erable, B.; Sablayrolles, C.; Escadeillas, G.; Albrecht, A.

    2013-07-01

    This study investigates the fate of nitrate and organic acids at the bitumenconcrete-steel interface within a repository storage cell for long-lived, intermediatelevel, radioactive wastes. The interface was simulated by a multiphase system in which cementitious matrices (CEM V-paste specimens) were exposed to bitumen model leachates consisting of nitrates and acetic acid with and without oxalic acid, chemical compounds likely to be released by bitumen. Leaching experiments were conducted with daily renewal of the solutions in order to accelerate reactions. C-steel chips, simulating the presence of steel in the repository, were added in the systems for some experiments. The concentrations of anions (acetate, oxalate, nitrate, and nitrite) and cations (calcium, potassium, ammonium) and the pH were monitored over time. Mineralogical changes of the cementitious matrices were analysed by XRD. The results confirmed the stability of nitrates in the absence of steel, whereas, reduction of nitrates was observed in the presence of steel (production of NH4+). The action of acetic acid on the cementitious matrix was similar to that of ordinary leaching; no specific interaction was detected between acetate and cementitious cations. The reaction of oxalic acid with the cementitious phases led to the precipitation of calcium oxalate salts in the outer layer of the matrix. The concentration of oxalate was reduced by 65% inside the leaching medium.

  6. Evidence of strong projectile-target-core interaction in single ionization of neon by electron impact

    SciTech Connect

    Yan, S.; Zhang, P.; Xu, S.; Ma, X.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Liu, H. P.

    2010-11-15

    The momentum distributions of recoil ions were measured in the single ionization of neon by electron impact at incident energies between 80 and 2300 eV. It was found that there are a noticeable number of recoil ions carrying large momenta, and the relative contributions of these ions becomes more pronounced with the further decrease of incident electron energy. These observed behaviors indicate that there is a strong projectile-target-core interaction in the single-ionization reaction. By comparing our results with those of electron-neon elastic scattering, we concluded that the elastic scattering of the projectile electron on the target core plays an important role at low and intermediate collision energies.

  7. Interaction between magnetic vortex cores in a pair of nonidentical nanodisks

    SciTech Connect

    Sinnecker, J. P.; Vigo-Cotrina, H.; Garcia, F.; Novais, E. R. P.; Guimarães, A. P.

    2014-05-28

    The coupling of two nonidentical magnetic nanodisks, i.e., with different vortex gyrotropic frequencies, is studied. From the analytical approach, the interactions between the nanodisks along x and y directions (the coupling integrals) were obtained as a function of distance. From the numerical solution of Thiele's equation, we derived the eigenfrequencies of the vortex cores as a function of distance. The motion of the two vortex cores and, consequently, the time dependence of the total magnetization M(t) were derived both using Thiele's equation and by micromagnetic simulation. From M(t), a recently developed method, the magnetic vortex echoes, analogous to the Nuclear Magnetic Resonance spin echoes, was used to compute the distance dependence of the magnetic coupling strength. The results of the two approaches differ by approximately 10%; using one single term, a dependence with distance found is broadly in agreement with studies employing other techniques.

  8. The influence of inelastic neutrino interactions with light clusters on core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Yamada, Shoichi

    2014-12-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light clusters in hot nuclear matter on core-collapse supernova simulations. These interactions have been neglected in most hydrodynamical supernova simulations. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged- current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. We show that the heating rates of deuterons reach as high as ~ 10% of those of nucleons around the bottom of the gain region. On the other hand, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light clusters have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light clusters, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  9. Interaction between core protein of classical swine fever virus with cellular IQGAP1 proetin appears essential for virulence in swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Here we show that IQGAP1, a cellular protein that plays a pivotal role as a regulator of the cytoskeleton affecting cell adhesion, polarization and migration, interacts with Classical Swine Fever Virus (CSFV) Core protein. Sequence analyses identified a defined set of residues within CSFV Core prote...

  10. Do Core Interpersonal and Affective Traits of PCL-R Psychopathy Interact with Antisocial Behavior and Disinhibition to Predict Violence?

    ERIC Educational Resources Information Center

    Kennealy, Patrick J.; Skeem, Jennifer L.; Walters, Glenn D.; Camp, Jacqueline

    2010-01-01

    The utility of psychopathy measures in predicting violence is largely explained by their assessment of social deviance (e.g., antisocial behavior; disinhibition). A key question is whether social deviance "interacts" with the core interpersonal-affective traits of psychopathy to predict violence. Do core psychopathic traits multiply the (already…

  11. Ms1, a novel sRNA interacting with the RNA polymerase core in mycobacteria

    PubMed Central

    Hnilicová, Jarmila; Jirát Matějčková, Jitka; Šiková, Michaela; Pospíšil, Jiří; Halada, Petr; Pánek, Josef; Krásný, Libor

    2014-01-01

    Small RNAs (sRNAs) are molecules essential for a number of regulatory processes in the bacterial cell. Here we characterize Ms1, a sRNA that is highly expressed in Mycobacterium smegmatis during stationary phase of growth. By glycerol gradient ultracentrifugation, RNA binding assay, and RNA co-immunoprecipitation, we show that Ms1 interacts with the RNA polymerase (RNAP) core that is free of the primary sigma factor (σA) or any other σ factor. This contrasts with the situation in most other species where it is 6S RNA that interacts with RNAP and this interaction requires the presence of σA. The difference in the interaction of the two types of sRNAs (Ms1 or 6S RNA) with RNAP possibly reflects the difference in the composition of the transcriptional machinery between mycobacteria and other species. Unlike Escherichia coli, stationary phase M. smegmatis cells contain relatively few RNAP molecules in complex with σA. Thus, Ms1 represents a novel type of small RNAs interacting with RNAP. PMID:25217589

  12. Emergence of rotational bands in ab initio no-core configuration interaction calculations of light nuclei

    NASA Astrophysics Data System (ADS)

    Caprio, Mark A.; Maris, Pieter; Vary, James P.

    2014-03-01

    The emergence of rotational bands has recently been observed in no-core configuration interaction (NCCI) calculations for p-shell nuclei, as evidenced by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. Yrast and low-lying excited bands are found. The results demonstrate the possibility of well-developed rotational structure in NCCI calculations, using realistic nucleon-nucleon interactions, and within finite, computationally-accessible configuration spaces. This talk will focus on results for rotation in both the even-mass and odd-mass Be isotopes (7 <= A <= 12). Supported by US DOE (DE-FG02-95ER-40934, DESC0008485 SciDAC/NUCLEI, DE-FG02-87ER40371), US NSF (0904782), and Research Corporation for Science Advancement (Cottrell Scholar Award). Computational resources provided by NERSC (US DOE DE-AC02-05CH11231).

  13. Ab Initio No-Core Shell Model Calculations Using Realistic Two- and Three-Body Interactions

    SciTech Connect

    Navratil, P; Ormand, W E; Forssen, C; Caurier, E

    2004-11-30

    There has been significant progress in the ab initio approaches to the structure of light nuclei. One such method is the ab initio no-core shell model (NCSM). Starting from realistic two- and three-nucleon interactions this method can predict low-lying levels in p-shell nuclei. In this contribution, we present a brief overview of the NCSM with examples of recent applications. We highlight our study of the parity inversion in {sup 11}Be, for which calculations were performed in basis spaces up to 9{Dirac_h}{Omega} (dimensions reaching 7 x 10{sup 8}). We also present our latest results for the p-shell nuclei using the Tucson-Melbourne TM three-nucleon interaction with several proposed parameter sets.

  14. Molecular interactions and metal binding in the theophylline-binding core of an RNA aptamer.

    PubMed Central

    Zimmermann, G R; Wick, C L; Shields, T P; Jenison, R D; Pardi, A

    2000-01-01

    An RNA aptamer containing a 15-nt binding site shows high affinity and specificity for the bronchodilator theophylline. A variety of base modifications or 2' deoxyribose substitutions in binding-site residues were tested for theophyllinebinding affinity and the results were compared with the previously determined three-dimensional structure of the RNA-theophylline complex. The RNA-theophylline complex contains a U6-A28-U23 base triple, and disruption of this A28-U23 Hoogsteen-pair by a 7-deaza, 2'-deoxy A28 mutant reduces theophylline binding >45-fold at 25 degrees C. U24 is part of a U-turn in the core of the RNA, and disruption of this U-turn motif by a 2'-deoxy substitution of U24 also reduces theophylline binding by >90-fold. Several mutations outside the "conserved core" of the RNA aptamer showed reduced binding affinity, and these effects could be rationalized by comparison with the three-dimensional structure of the complex. Divalent ions are absolutely required for high-affinity theophylline binding. High-affinity binding was observed with 5 mM Mg2+, Mn2+, or Co2+ ions, whereas little or no significant binding was observed for other divalent or lanthanide ions. A metal-binding site in the core of the complex was revealed by paramagnetic Mn2+-induced broadening of specific RNA resonances in the NMR spectra. When caffeine is added to the aptamer in tenfold excess, the NMR spectra show no evidence for binding in the conserved core and instead the drug stacks on the terminal helix. The lack of interaction between caffeine and the theophylline-binding site emphasizes the extreme molecular discrimination of this RNA aptamer. PMID:10836787

  15. Interaction of sigma factor sigmaN with Escherichia coli RNA polymerase core enzyme.

    PubMed Central

    Scott, D J; Ferguson, A L; Gallegos, M T; Pitt, M; Buck, M; Hoggett, J G

    2000-01-01

    The equilibrium binding and kinetics of assembly of the DNA-dependent RNA polymerase (RNAP) sigma(N)-holoenzyme has been investigated using biosynthetically labelled 7-azatryptophyl- (7AW)sigma(N). The spectroscopic properties of such 7AW proteins allows their absorbance and fluorescence to be monitored selectively, even in the presence of high concentrations of other tryptophan-containing proteins. The 7AWsigma(N) retained its biological activity in stimulating transcription from sigma(N)-specific promoters, and in in vitro gel electrophoresis assays of binding to core RNAP from Escherichia coli. Furthermore, five Trp-->Ala single mutants of sigma(N) were shown to support growth under conditions of nitrogen limitation, and showed comparable efficiency in activating the sigma(N)-dependent nifH promoter in vivo, indicating that none of the tryptophan residues were essential for activity. The equilibrium binding of 7AWsigma(N) to core RNAP was examined by analytical ultracentrifugation. In sedimentation equilibrium experiments, absorbance data at 315 nm (which reports selectively on the distribution of free and bound 7AWsigma(N)) established that a 1:1 complex was formed, with a dissociation constant lower than 2 microM. The kinetics of the interaction between 7AWsigma(N) and core RNAP was investigated using stopped-flow spectrofluorimetry. A biphasic decrease in fluorescence intensity was observed when samples were excited at 280 nm, whereas only the slower of the two phases was observed at 315 nm. The kinetic data were analysed in terms of a mechanism in which a fast bimolecular association of sigma(N) with core RNAP is followed by a relatively slow isomerization step. The consequences of these findings on the competition between sigma(N) and the major sigma factor, sigma(70), in Escherichia coli are discussed. PMID:11085949

  16. Interaction of sigma factor sigmaN with Escherichia coli RNA polymerase core enzyme.

    PubMed

    Scott, D J; Ferguson, A L; Gallegos, M T; Pitt, M; Buck, M; Hoggett, J G

    2000-12-01

    The equilibrium binding and kinetics of assembly of the DNA-dependent RNA polymerase (RNAP) sigma(N)-holoenzyme has been investigated using biosynthetically labelled 7-azatryptophyl- (7AW)sigma(N). The spectroscopic properties of such 7AW proteins allows their absorbance and fluorescence to be monitored selectively, even in the presence of high concentrations of other tryptophan-containing proteins. The 7AWsigma(N) retained its biological activity in stimulating transcription from sigma(N)-specific promoters, and in in vitro gel electrophoresis assays of binding to core RNAP from Escherichia coli. Furthermore, five Trp-->Ala single mutants of sigma(N) were shown to support growth under conditions of nitrogen limitation, and showed comparable efficiency in activating the sigma(N)-dependent nifH promoter in vivo, indicating that none of the tryptophan residues were essential for activity. The equilibrium binding of 7AWsigma(N) to core RNAP was examined by analytical ultracentrifugation. In sedimentation equilibrium experiments, absorbance data at 315 nm (which reports selectively on the distribution of free and bound 7AWsigma(N)) established that a 1:1 complex was formed, with a dissociation constant lower than 2 microM. The kinetics of the interaction between 7AWsigma(N) and core RNAP was investigated using stopped-flow spectrofluorimetry. A biphasic decrease in fluorescence intensity was observed when samples were excited at 280 nm, whereas only the slower of the two phases was observed at 315 nm. The kinetic data were analysed in terms of a mechanism in which a fast bimolecular association of sigma(N) with core RNAP is followed by a relatively slow isomerization step. The consequences of these findings on the competition between sigma(N) and the major sigma factor, sigma(70), in Escherichia coli are discussed. PMID:11085949

  17. The glycosylation-dependent interaction of perlecan core protein with LDL: implications for atherosclerosis[S

    PubMed Central

    Xu, Yu-Xin; Ashline, David; Liu, Li; Tassa, Carlos; Shaw, Stanley Y.; Ravid, Katya; Layne, Matthew D.; Reinhold, Vernon; Robbins, Phillips W.

    2015-01-01

    Perlecan is a major heparan sulfate (HS) proteoglycan in the arterial wall. Previous studies have linked it to atherosclerosis. Perlecan contains a core protein and three HS side chains. Its core protein has five domains (DI–DV) with disparate structures and DII is highly homologous to the ligand-binding portion of LDL receptor (LDLR). The functional significance of this domain has been unknown. Here, we show that perlecan DII interacts with LDL. Importantly, the interaction largely relies on O-linked glycans that are only present in the secreted DII. Among the five repeat units of DII, most of the glycosylation sites are from the second unit, which is highly divergent and rich in serine and threonine, but has no cysteine residues. Interestingly, most of the glycans are capped by the negatively charged sialic acids, which are critical for LDL binding. We further demonstrate an additive effect of HS and DII on LDL binding. Unlike LDLR, which directs LDL uptake through endocytosis, this study uncovers a novel feature of the perlecan LDLR-like DII in receptor-mediated lipoprotein retention, which depends on its glycosylation. Thus, perlecan glycosylation may play a role in the early LDL retention during the development of atherosclerosis. PMID:25528754

  18. Interactions between plutonism and detachments during metamorphic core complex formation, Serifos Island (Cyclades, Greece)

    NASA Astrophysics Data System (ADS)

    Rabillard, Aurélien; Arbaret, Laurent; Jolivet, Laurent; Le Breton, Nicole; Gumiaux, Charles; Augier, Romain; Grasemann, Bernhard

    2015-06-01

    In order to better understand the interactions between plutonic activity and strain localization during metamorphic core complex formation, the Miocene granodioritic pluton of Serifos (Cyclades, Greece) is studied. This pluton (11.6-9.5 Ma) intruded the Cycladic Blueschists during thinning of the Aegean domain along a system of low-angle normal faults belonging to the south dipping West Cycladic Detachment System (WCDS). Based on structural fieldwork, together with microstructural observations and anisotropy of magnetic susceptibility, we recognize a continuum of deformation from magmatic to brittle conditions within the magmatic body. This succession of deformation events is kinematically compatible with the development of the WCDS. The architecture of the pluton shows a marked asymmetry resulting from its interaction with the detachments. We propose a tectonic scenario for the emplacement of Serifos pluton and its subsequent cooling during the Aegean extension: (1) A first stage corresponds to the metamorphic core complex initiation and associated southwestward shearing along the Meghàlo Livadhi detachment. (2) In the second stage, the Serifos pluton has intruded the dome at shallow crustal level, piercing through the ductile/brittle Meghàlo Livadhi detachment. Southwest directed extensional deformation was contemporaneously transferred upward in the crust along the more localized Kàvos Kiklopas detachment. (3) The third stage was marked by synmagmatic extensional deformation and strain localization at the contact between the pluton and the host rocks resulting in nucleation of narrow shear zones, which (4) continued to develop after the pluton solidification.

  19. Effects of hydrophobic drug polyesteric core interactions on drug loading and release properties of poly(ethylene glycol) polyester poly(ethylene glycol) triblock core shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Khoee, Sepideh; Hassanzadeh, Salman; Goliaie, Bahram

    2007-05-01

    BAB amphiphilic triblock copolymers consisting of poly(ethylene glycol) (B) (PEG) as the hydrophilic segment and different polyesters (A) as the hydrophobic block were prepared by a polycondensation reaction as efficient model core-shell nanoparticles to assay the effect of interactions between the hydrophobic drug and the polyesteric core in terms of drug loading content and release profile. PEG-poly(hexylene adipate)-PEG (PEG-PHA-PEG) and PEG-poly(butylene adipate)-PEG (PEG-PBA-PEG) to PEG-poly(ethylene adipate)-PEG (PEG-PEA-PEG) core-shell type nanoparticles entrapping quercetin (an anticarcinogenic, allergy inhibitor and antibacterial agent), were prepared by a nanoprecipitation method and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD) techniques. It was found that the obtained nanoparticles showed a smooth surface and spherical shape with controllable sizes in the range of 64-74 nm, while drug loading varied from 7.24% to 19% depending on the copolymer composition and the preparation conditions. The in vitro release behaviour exhibited a sustained release and was affected by the polymer-drug interactions. UV studies revealed the presence of hydrogen bonding as the main existing interaction between quercetin and polyesters in the nanosphere cores.

  20. Thermal interaction of the core and the mantle and long-term behavior of the geomagnetic field

    NASA Technical Reports Server (NTRS)

    Jones, G. M.

    1977-01-01

    The effects of temperature changes at the earth's core-mantle boundary on the velocity field of the core are analyzed. It is assumed that the geomagnetic field is maintained by thermal convection in the outer core. A model for the thermal interaction of the core and the mantle is presented which is consistent with current views on the presence of heat sources in the core and the properties of the lower mantle. Significant long-term variations in the frequency of geomagnetic reversals may be the result of fluctuating temperatures at the core-mantle boundary, caused by intermittent convection in the lower mantle. The thermal structure of the lower mantle region D double prime, extending from 2700 to 2900 km in depth, constitutes an important test of this hypothesis and offers a means of deciding whether the geomagnetic dynamo is thermally driven.

  1. Effect of subdomain interactions on methyl group dynamics in the hydrophobic core of villin headpiece protein

    PubMed Central

    Vugmeyster, Liliya; Do, Tien; Ostrovsky, Dmitry; Fu, Riqianq

    2014-01-01

    Thermostable villin headpiece protein (HP67) consists of the N-terminal subdomain (residues 10–41) and the autonomously folding C-terminal subdomain (residues 42–76) which pack against each other to form a structure with a unified hydrophobic core. The X-ray structures of the isolated C-terminal subdomain (HP36) and its counterpart in HP67 are very similar for the hydrophobic core residues. However, fine rearrangements of the free energy landscape are expected to occur because of the interactions between the two subdomains. We detect and characterize these changes by comparing the µs-ms time scale dynamics of the methyl-bearing side chains in isolated HP36 and in HP67. Specifically, we probe three hydrophobic side chains at the interface of the two subdomains (L42, V50, and L75) as well as at two residues far from the interface (L61 and L69). Solid-state deuteron NMR techniques are combined with computational modeling for the detailed characterization of motional modes in terms of their kinetic and thermodynamic parameters. The effect of interdomain interactions on side chain dynamics is seen for all residues but L75. Thus, changes in dynamics because of subdomain interactions are not confined to the site of perturbation. One of the main results is a two-to threefold increase in the value of the activation energies for the rotameric mode of motions in HP67 compared with HP36. Detailed analysis of configurational entropies and heat capacities complement the kinetic view of the degree of the disorder in the folded state. PMID:24243806

  2. Results of detailed analyses performed on boring cores extracted from the concrete floors of the Fukushima Daiichi nuclear power plant reactor buildings

    SciTech Connect

    Maeda, Koji; Sasaki, S.; Kumai, M.; Sato, Isamu; Osaka, Masahiko; Fukushima, Mineo; Kawatsuma, Shinji; Goto, Tetsuo; Sakai, Hitoshi; Chigira, Takayuki; Murata, Hirotoshi

    2013-07-01

    Due to the massive earthquake and tsunami on March 11, 2011, and the following severe accident at the Fukushima Daiichi Nuclear Power Plant, concrete surfaces within the reactor buildings were exposed to radioactive liquid and vapor phase contaminants. In order to clarify the situation of this contamination in the reactor buildings of Units 1, 2 and 3, selected samples were transported to the Fuels Monitoring Facility in the Oarai Engineering Center of JAEA where they were subjected to analyses to determine the surface radionuclide concentrations and to characterize the radionuclide distributions in the samples. In particular, penetration of radiocesium in the surface coatings layer and sub-surface concrete was evaluated. The analysis results indicate that the situation of contamination in the building of Unit 2 was different from others, and the protective surface coatings on the concrete floors provided significant protection against radionuclide penetration. The localized penetration of contamination in the concrete floors was found to be confined within a millimeter of the surface of the coating layer of some millimeters. (authors)

  3. Marine concrete

    SciTech Connect

    Marshall, A.L.

    1990-01-01

    This book examines how the chemical and physical properties of the oceans affect the durability, fatigue, and corrosion of structures. Structure types addressed include oil platforms, arctic structures, and sea walls. Reviews qualities of plain, reinforced, prestressed, and floating concrete. Discusses the inspection, maintenance, and repair of concrete structures.

  4. Interaction of core self-evaluations and perceived organizational support on work-to-family enrichment.

    PubMed

    McNall, Laurel A; Masuda, Aline D; Shanock, Linda Rhoades; Nicklin, Jessica M

    2011-01-01

    The purpose of this article was to offer an empirical test of J. H. Greenhaus and G. N. Powell's (2006) model of work-family enrichment by examining dispositional (i.e., core self-evaluations; CSEs) and situational (i.e., perceived organizational support; POS) factors associated with work-to-family enrichment (WFE) and whether these variables interact in predicting WFE. In a survey of 220 employed adults, our hierarchical regression analysis revealed that in highly supportive work environments, individuals reported high WFE regardless of CSE. However, when POS was low, individuals high in CSEs reported higher WFE than those low in CSEs, in support of conservation of resources theory (S. E. Hobfoll, 2002). Implications for research and practice are discussed. PMID:21449248

  5. Interactions between tetrathiafulvalene units in dimeric structures - the influence of cyclic cores.

    PubMed

    Jiang, Huixin; Mazzanti, Virginia; Parker, Christian R; Broman, Søren Lindbæk; Wallberg, Jens Heide; Lušpai, Karol; Brincko, Adam; Kjaergaard, Henrik G; Kadziola, Anders; Rapta, Peter; Hammerich, Ole; Nielsen, Mogens Brøndsted

    2015-01-01

    A selection of cyclic and acyclic acetylenic scaffolds bearing two tetrathiafulvalene (TTF) units was prepared by different metal-catalyzed coupling reactions. The bridge separating the two TTF units was systematically changed from linearly conjugated ethyne, butadiyne and tetraethynylethene (trans-substituted) units to a cross-conjugated tetraethynylethene unit, placed in either acyclic or cyclic arrangements. The cyclic structures correspond to so-called radiaannulenes having both endo- and exocyclic double bonds. Interactions between two redox-active TTF units in these molecules were investigated by cyclic voltammetry, UV-vis-NIR and EPR absorption spectroscopical methods of the electrochemically generated oxidized species. The electron-accepting properties of the acetylenic cores were also investigated electrochemically. PMID:26124895

  6. Kaleidoscope of supersolid phases of interacting hard-core bosons on the dice lattice

    NASA Astrophysics Data System (ADS)

    Lv, Jian-Ping

    2015-05-01

    The stability of supersolid (SS) state in lattice boson model is highly dependent on lattice topology and particle-particle interaction. We investigate hard-core bosons on dice lattice where the bosons interact via nearest-neighbor (NN) repulsion either on whole lattice or on sublattices, by using large-scale quantum Monte Carlo simulations which are based on a continuous-time worm algorithm. In the case with NN repulsion on the whole lattice, we confirm the particle density modulation which arises from the asymmetry between sublattices — honeycomb and triangular sublattices — of dice lattice. We then place emphasis on the case with NN repulsion on the sublattices, and demonstrate spontaneously broken translational symmetries on different sublattices which lead to various crystalline orders. By evaluating the coexistence of crystalline order and superfluidity, we identify a variety of SS phases and establish a rich phase diagram. The microscopic pictures of these SS phases are figured out. Further, we demonstrate paradigmatic examples of first-order solid-to-SS and SS-to-SS quantum phase transitions.

  7. Carbonation and its effects in reinforced concrete

    SciTech Connect

    Broomfield, J.P.

    2000-01-01

    Carbonation is the result of interaction of carbon dioxide (CO{sub 2}) gas in the atmosphere with the alkaline hydroxides in the concrete. CO{sub 2} diffuses through the concrete and rate of movement of the carbonation front roughly follows Fick's law of diffusion. Carbonation depth can be measured by exposing fresh concrete and spraying it with phenolphthalein indicator solution. An example of the test on a reinforced concrete mullion is given.

  8. Regulation of ASPP2 Interaction with p53 Core Domain by an Intramolecular Autoinhibitory Mechanism

    PubMed Central

    Rotem-Bamberger, Shahar; Katz, Chen; Friedler, Assaf

    2013-01-01

    ASPP2 is a key protein in regulating apoptosis both in p53-dependent and-independent pathways. The C-terminal part of ASPP2 contains four ankyrin repeats and an SH3 domain (Ank-SH3) that mediate the interactions of ASPP2 with apoptosis related proteins such as p53, Bcl-2 and the p65 subunit of NFκB. p53 core domain (p53CD) binds the n-src loop and the RT loop of ASPP2 SH3. ASPP2 contains a disordered proline rich domain (ASPP2 Pro) that forms an intramolecular autoinhibitory interaction with the Ank-SH3 domains. Here we show how this intramolecular interaction affects the intermolecular interactions of ASPP2 with p53, Bcl-2 and NFkB. We used biophysical methods to obtain better understanding of the relationship between ASPP2 and its partners for getting a comprehensive view on ASPP2 pathways. Fluorescence anisotropy competition experiments revealed that both ASPP2 Pro and p53CD competed for binding the n-src loop of the ASPP2 SH3, indicating regulation of p53CD binding to this loop by ASPP2 Pro. Peptides derived from the ASPP2-binding interface of Bcl-2 did not compete with p53CD or NFkB peptides for binding the ASPP2 n-src loop. However, p53CD displaced the NFκB peptide (residues 303–332) from its complex with ASPP2 Ank-SH3, indicating that NFκB 303–332 and p53CD bind a partly overlapping site in ASPP2 SH3, mostly in the RT loop. These results are in agreement with previous docking studies, which showed that ASPP2 Ank-SH3 binds Bcl-2 and NFκB mostly via distinct sites from p53. However they show some overlap between the binding sites of p53CD and NFkB in ASPP2 Ank-SH3. Our results provide experimental evidence that the intramolecular interaction in ASPP2 regulates its binding to p53CD and that ASPP2 Ank-SH3 binds Bcl-2 and NFκB via distinct sites. PMID:23472201

  9. Composition, nucleation, and growth of iron oxide concretions

    NASA Astrophysics Data System (ADS)

    Parry, W. T.

    Iron oxide concretions are formed from post depositional, paleogroundwater chemical interaction with iron minerals in porous sedimentary rocks. The concretions record a history of iron mobilization and precipitation caused by changes in pH, oxidation conditions, and activity of bacteria. Transport limited growth rates may be used to estimate the duration of fluid flow events. The Jurassic Navajo Sandstone, an important hydrocarbon reservoir and aquifer on the Colorado Plateau, USA, is an ideal stratum to study concretions because it is widely distributed, well exposed and is the host for a variety of iron oxide concretions. Many of the concretions are nearly spherical and some consist of a rind of goethite that nearly completely fills the sandstone porosity and surrounds a central sandstone core. The interior and exterior host-rock sandstones are similar in detrital minerals, but kaolinite and interstratified illite-smectite are less abundant in the interior. Lepidocrocite is present as sand-grain rims in the exterior sandstone, but not present in the interior of the concretions. Widespread sandstone bleaching resulted from dissolution of early diagenetic hematite grain coatings by chemically reducing water that gained access to the sandstone through fault conduits. The iron was transported in solution and precipitated as iron oxide concretions by oxidation and increasing pH. Iron diffusion and advection growth time models place limits on minimum duration of the diagenetic, fluid flow events that formed the concretions. Concretion rinds 2 mm thick and 25 mm in radius would take place in 2000 years from transport by diffusion and advection and in 3600 years if transport was by diffusion only. Solid concretions 10 mm in radius would grow in 3800 years by diffusion or 2800 years with diffusion and advection. Goethite (α-FeO (OH)) and lepidocrocite (γ-FeO (OH)) nucleated on K-feldspar grains, on illite coatings on sand grains, and on pore-filling illite, but not on

  10. IRAS16293E revisited: a new understanding of a prestellar core in interaction with an outflow

    NASA Astrophysics Data System (ADS)

    Pagani, L.; Lefèvre, C.; Belloche, A.; Menten, K.; Parise, B.; Güsten, R.

    2016-05-01

    The study of prestellar cores starts with establishing their density and temperature structures. To explore the densest part, deu-terated species, N-bearing molecules, or dust are usually considered. Among prestellar cores, IRAS16293E is a rare case of a core being perturbed by the outflow of a nearby protostar (IRAS16293-2422 A/B). A part of the outflow hits the core and heats it, introducing a temperature gradient that makes the analysis difficult. It is only after having gathered observations from Spitzer, Herschel, SCUBA, MAMBO, and of various molecular lines from CSO, APEX, JCMT and IRAM that a clearer picture of this core has finally arisen.

  11. Emergence of rotational bands in ab initio no-core configuration interaction calculations of the Be isotopes

    NASA Astrophysics Data System (ADS)

    Maris, P.; Caprio, M. A.; Vary, J. P.

    2015-01-01

    The emergence of rotational bands is observed in no-core configuration interaction (NCCI) calculations for the Be isotopes (7 ≤A ≤12 ), as evidenced by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. Yrast and low-lying excited bands are found. The results indicate well-developed rotational structure in NCCI calculations, using the JISP16 realistic nucleon-nucleon interaction within finite, computationally accessible configuration spaces.

  12. Ab initio no core configuration interaction calculations in the natural orbital basis

    NASA Astrophysics Data System (ADS)

    Constantinou, Chrysovalantis; Caprio, Mark A.; Vary, James P.; Maris, Pieter

    2015-10-01

    The natural orbital basis has been successfully used in the past in atomic and molecular structure calculations. The natural orbitals used in those calculations are calculated by diagonalizing the electron one-body density matrix. Here we develop natural orbitals for nuclear no-core configuration interaction (NCCI) calculations. A NCCI calculation using an initial single particle basis, such as the harmonic oscillator basis, must first be performed in order to obtain a one-body density matrix. The eigenvectors of the one-body density matrix are the natural orbitals, and the corresponding eigenvalues are the occupations of these natural orbitals in the nuclear wave function. According to these occupancies, the most important natural orbitals, in the sense of the most occupied, can then be selected and used in a NCCI calculation. We discuss ab initio nuclear NCCI calculations for light nuclei and assess their ability to provide faster convergence. Supported by the US DOE (under Grants DE-FG02-95ER-40934, DESC0008485 SciDAC/NUCLEI, and DE-FG02-87ER40371), and the US NSF (under Grant 0904782). Computational resources provided by NERSC (supported by US DOE Contract DE-AC02-05CH11231), and NDCRC.

  13. EJC core component MLN51 interacts with eIF3 and activates translation.

    PubMed

    Chazal, Pierre-Etienne; Daguenet, Elisabeth; Wendling, Corinne; Ulryck, Nathalie; Tomasetto, Catherine; Sargueil, Bruno; Le Hir, Hervé

    2013-04-01

    The multiprotein exon junction complex (EJC), deposited by the splicing machinery, is an important constituent of messenger ribonucleoprotein particles because it participates to numerous steps of the mRNA lifecycle from splicing to surveillance via nonsense-mediated mRNA decay pathway. By an unknown mechanism, the EJC also stimulates translation efficiency of newly synthesized mRNAs. Here, we show that among the four EJC core components, the RNA-binding protein metastatic lymph node 51 (MLN51) is a translation enhancer. Overexpression of MLN51 preferentially increased the translation of intron-containing reporters via the EJC, whereas silencing MLN51 decreased translation. In addition, modulation of the MLN51 level in cell-free translational extracts confirmed its direct role in protein synthesis. Immunoprecipitations indicated that MLN51 associates with translation-initiating factors and ribosomal subunits, and in vitro binding assays revealed that MLN51, alone or as part of the EJC, interacts directly with the pivotal eukaryotic translation initiation factor eIF3. Taken together, our data define MLN51 as a translation activator linking the EJC and the translation machinery. PMID:23530232

  14. EJC core component MLN51 interacts with eIF3 and activates translation

    PubMed Central

    Chazal, Pierre-Etienne; Daguenet, Elisabeth; Wendling, Corinne; Ulryck, Nathalie; Tomasetto, Catherine; Sargueil, Bruno; Le Hir, Hervé

    2013-01-01

    The multiprotein exon junction complex (EJC), deposited by the splicing machinery, is an important constituent of messenger ribonucleoprotein particles because it participates to numerous steps of the mRNA lifecycle from splicing to surveillance via nonsense-mediated mRNA decay pathway. By an unknown mechanism, the EJC also stimulates translation efficiency of newly synthesized mRNAs. Here, we show that among the four EJC core components, the RNA-binding protein metastatic lymph node 51 (MLN51) is a translation enhancer. Overexpression of MLN51 preferentially increased the translation of intron-containing reporters via the EJC, whereas silencing MLN51 decreased translation. In addition, modulation of the MLN51 level in cell-free translational extracts confirmed its direct role in protein synthesis. Immunoprecipitations indicated that MLN51 associates with translation-initiating factors and ribosomal subunits, and in vitro binding assays revealed that MLN51, alone or as part of the EJC, interacts directly with the pivotal eukaryotic translation initiation factor eIF3. Taken together, our data define MLN51 as a translation activator linking the EJC and the translation machinery. PMID:23530232

  15. GENIE: a software package for gene-gene interaction analysis in genetic association studies using multiple GPU or CPU cores

    PubMed Central

    2011-01-01

    Background Gene-gene interaction in genetic association studies is computationally intensive when a large number of SNPs are involved. Most of the latest Central Processing Units (CPUs) have multiple cores, whereas Graphics Processing Units (GPUs) also have hundreds of cores and have been recently used to implement faster scientific software. However, currently there are no genetic analysis software packages that allow users to fully utilize the computing power of these multi-core devices for genetic interaction analysis for binary traits. Findings Here we present a novel software package GENIE, which utilizes the power of multiple GPU or CPU processor cores to parallelize the interaction analysis. GENIE reads an entire genetic association study dataset into memory and partitions the dataset into fragments with non-overlapping sets of SNPs. For each fragment, GENIE analyzes: 1) the interaction of SNPs within it in parallel, and 2) the interaction between the SNPs of the current fragment and other fragments in parallel. We tested GENIE on a large-scale candidate gene study on high-density lipoprotein cholesterol. Using an NVIDIA Tesla C1060 graphics card, the GPU mode of GENIE achieves a speedup of 27 times over its single-core CPU mode run. Conclusions GENIE is open-source, economical, user-friendly, and scalable. Since the computing power and memory capacity of graphics cards are increasing rapidly while their cost is going down, we anticipate that GENIE will achieve greater speedups with faster GPU cards. Documentation, source code, and precompiled binaries can be downloaded from http://www.cceb.upenn.edu/~mli/software/GENIE/. PMID:21615923

  16. Interaction of Hepatitis C Virus Core Protein with Janus Kinase Is Required for Efficient Production of Infectious Viruses

    PubMed Central

    Lee, Choongho

    2013-01-01

    Chronic hepatitis C virus (HCV) infection is responsible for the development of liver cirrhosis and hepatocellular carcinoma. HCV core protein plays not only a structural role in the virion morphogenesis by encapsidating a virus RNA genome but also a non-structural role in HCV-induced pathogenesis by blocking innate immunity. Especially, it has been shown to regulate JAK-STAT signaling pathway through its direct interaction with Janus kinase (JAK) via its proline-rich JAK-binding motif (79PGYPWP84). However, little is known about the physiological significance of this HCV core-JAK association in the context of the virus life cycle. In order to gain an insight, a mutant HCV genome (J6/JFH1-79A82A) was constructed to express the mutant core with a defective JAK-binding motif (79AGYAWP84) using an HCV genotype 2a infectious clone (J6/JFH1). When this mutant HCV genome was introduced into hepatocarcinoma cells, it was found to be severely impaired in its ability to produce infectious viruses in spite of its robust RNA genome replication. Taken together, all these results suggest an essential requirement of HCV core-JAK protein interaction for efficient production of infectious viruses and the potential of using core-JAK blockers as a new anti-HCV therapy. PMID:24009866

  17. Identification of three regions essential for interaction between a σ-like factor and core RNA polymerase

    PubMed Central

    Cliften, Paul F.; Park, Jae-Young; Davis, Brian P.; Jang, Sei-Heon; Jaehning, Judith A.

    1997-01-01

    The cyclic interactions that occur between the subunits of the yeast mitochondrial RNA polymerase can serve as a simple model for the more complex enzymes in prokaryotes and the eukaryotic nucleus. We have used two-hybrid and fusion protein constructs to analyze the requirements for interaction between the single subunit core polymerase (Rpo41p), and the σ-like promoter specificity factor (Mtf1p). We were unable to define any protein truncations that retained the ability to interact, indicating that multiple regions encompassing the entire length of the proteins are involved in interactions. We found that 9 of 15 nonfunctional (petite) point mutations in Mtf1p isolated in a plasmid shuffle strategy had lost the ability to interact. Some of the noninteracting mutations are temperature-sensitive petite (ts petite); this phenotype correlates with a precipitous drop in mitochondrial transcript abundance when cells are shifted to the nonpermissive temperature. One temperature-sensitive mutant demonstrated a striking pH dependence for core binding in vitro, consistent with the physical properties of the amino acid substitution. The noninteracting mutations fall into three widely spaced clusters of amino acids. Two of the clusters are in regions with amino acid sequence similarity to conserved regions 2 and 3 of σ factors and related proteins; these regions have been implicated in core binding by both prokaryotic and eukaryotic σ-like factors. By modeling the location of the mutations using the partial structure of Escherichia coli σ70, we find that two of the clusters are potentially juxtaposed in the three-dimensional structure. Our results demonstrate that interactions between σ-like specificity factors and core RNA polymerases require multiple regions from both components of the holoenzymes. PMID:9353258

  18. No-core configuration-interaction model for the isospin- and angular-momentum-projected states

    NASA Astrophysics Data System (ADS)

    Satuła, W.; Båczyk, P.; Dobaczewski, J.; Konieczka, M.

    2016-08-01

    Background: Single-reference density functional theory is very successful in reproducing bulk nuclear properties like binding energies, radii, or quadrupole moments throughout the entire periodic table. Its extension to the multireference level allows for restoring symmetries and, in turn, for calculating transition rates. Purpose: We propose a new variant of the no-core-configuration-interaction (NCCI) model treating properly isospin and rotational symmetries. The model is applicable to any nucleus irrespective of its mass and neutron- and proton-number parity. It properly includes polarization effects caused by an interplay between the long- and short-range forces acting in the atomic nucleus. Methods: The method is based on solving the Hill-Wheeler-Griffin equation within a model space built of linearly dependent states having good angular momentum and properly treated isobaric spin. The states are generated by means of the isospin and angular-momentum projection applied to a set of low-lying (multi)particle-(multi)hole deformed Slater determinants calculated using the self-consistent Skyrme-Hartree-Fock approach. Results: The theory is applied to calculate energy spectra in N ≈Z nuclei that are relevant from the point of view of a study of superallowed Fermi β decays. In particular, a new set of the isospin-symmetry-breaking corrections to these decays is given. Conclusions: It is demonstrated that the NCCI model is capable of capturing main features of low-lying energy spectra in light and medium-mass nuclei using relatively small model space and without any local readjustment of its low-energy coupling constants. Its flexibility and a range of applicability makes it an interesting alternative to the conventional nuclear shell model.

  19. Inhibitory Control Interacts with Core Knowledge in Toddlers' Manual Search for an Occluded Object

    ERIC Educational Resources Information Center

    Baker, Sara T.; Gjersoe, Nathalia L.; Sibielska-Woch, Kasia; Leslie, Alan M.; Hood, Bruce M.

    2011-01-01

    Core knowledge theories advocate the primacy of fundamental principles that constrain cognitive development from early infancy. However, there is concern that core knowledge of object properties does not constrain older preschoolers' reasoning during manual search. Here we address in detail both failure and success on two well-established search…

  20. Setting the Stage for Circumstellar Interaction in Core-Collapse Supernovae. II. Wave-driven Mass Loss in Supernova Progenitors

    NASA Astrophysics Data System (ADS)

    Shiode, Joshua H.; Quataert, Eliot

    2014-01-01

    Supernovae (SNe) powered by interaction with circumstellar material provide evidence for intense stellar mass loss during the final years before core collapse. We have argued that during and after core neon burning, internal gravity waves excited by core convection can tap into the core fusion power and transport a super-Eddington energy flux out to the stellar envelope, potentially unbinding ~1 solar mass of material. In this work, we explore the internal conditions of SN progenitors using the MESA one-dimensional stellar evolution code in search of those most susceptible to wave-driven mass loss. We focus on simple, order of magnitude considerations applicable to a wide range of progenitors. Wave-driven mass loss during core neon and oxygen fusion happens preferentially in either lower mass (~20 solar mass zero-age main sequence) stars or massive, sub-solar metallicity stars. Roughly 20% of the SN progenitors we survey can excite 1046-48 erg of energy in waves that can potentially drive mass loss within a few months to a decade of core collapse. This energy can generate circumstellar environments with 10-3-1 solar masses reaching 100 AU before explosion. We predict a correlation between the energy associated with pre-SN mass ejection and the time to core collapse, with the most intense mass loss preferentially occurring closer to core collapse. During silicon burning, wave energy may inflate 10-3-1 solar masses of the envelope to 10-100 s of solar radii. This suggests that some nominally compact SN progenitors (Type Ibc progenitors) will have a significantly different SN shock breakout signature than traditionally assumed.

  1. Setting the stage for circumstellar interaction in core-collapse supernovae. II. Wave-driven mass loss in supernova progenitors

    SciTech Connect

    Shiode, Joshua H.; Quataert, Eliot E-mail: eliot@berkeley.edu

    2014-01-01

    Supernovae (SNe) powered by interaction with circumstellar material provide evidence for intense stellar mass loss during the final years before core collapse. We have argued that during and after core neon burning, internal gravity waves excited by core convection can tap into the core fusion power and transport a super-Eddington energy flux out to the stellar envelope, potentially unbinding ∼1 solar mass of material. In this work, we explore the internal conditions of SN progenitors using the MESA one-dimensional stellar evolution code in search of those most susceptible to wave-driven mass loss. We focus on simple, order of magnitude considerations applicable to a wide range of progenitors. Wave-driven mass loss during core neon and oxygen fusion happens preferentially in either lower mass (∼20 solar mass zero-age main sequence) stars or massive, sub-solar metallicity stars. Roughly 20% of the SN progenitors we survey can excite 10{sup 46-48} erg of energy in waves that can potentially drive mass loss within a few months to a decade of core collapse. This energy can generate circumstellar environments with 10{sup –3}-1 solar masses reaching 100 AU before explosion. We predict a correlation between the energy associated with pre-SN mass ejection and the time to core collapse, with the most intense mass loss preferentially occurring closer to core collapse. During silicon burning, wave energy may inflate 10{sup –3}-1 solar masses of the envelope to 10-100 s of solar radii. This suggests that some nominally compact SN progenitors (Type Ibc progenitors) will have a significantly different SN shock breakout signature than traditionally assumed.

  2. Osmium-187 enrichment in some plumes: Evidence for core-mantle interaction?

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.; Horan, M.F.

    1995-01-01

    Calculations with data for asteroidal cores indicate that Earth's outer core may have a rhenium/osmium ratio at least 20 percent greater than that of the chondritic upper mantle, potentially leading to an outer core with an osmium-187/osmium-188 ratio at least 8 percent greater than that of chondrites. Because of the much greater abundance of osmium in the outer core relative to the mantle, even a small addition of metal to a plume ascending from the D??? layer would transfer the enriched isotopic signature to the mixture. Sources of certain plume-derived systems seem to have osmium-187/osmium-188 ratios 5 to 20 percent greater than that for chondrites, consistent with the ascent of a plume from the core-mantle boundary.

  3. Extended-soft-core baryon-baryon model. II. Hyperon-nucleon interaction

    SciTech Connect

    Rijken, Th.A.; Yamamoto, Y.

    2006-04-15

    The YN results are presented from the extended soft-core (ESC) interactions. They consist of local and nonlocal potentials because of (i) one-boson exchanges (OBE), which are the members of nonets of pseudoscalar, vector, scalar, and axial mesons; (ii) diffractive exchanges; (iii) two-pseudoscalar exchange; and (iv) meson-pair exchange (MPE). Both the OBE and pair vertices are regulated by Gaussian form factors producing potentials with a soft behavior near the origin. The assignment of the cutoff masses for the baryon-baryon-meson (BBM) vertices is dependent on the SU(3) classification of the exchanged mesons for OBE and a similar scheme for MPE. The particular version of the ESC model, called ESC04 [T. A. Rijken, Phys. Rev. C 73, 044007 (2006)], describes nucleon-nucleon (NN) and hyperon-nucleon (YN) interactions in a unified way using broken SU(3) symmetry. Novel ingredients are the inclusion of (i) the axial-vector meson potentials and (ii) a zero in the scalar- and axial-vector meson form factors. These innovations made it possible for the first time to keep the parameters of the model close to the predictions of the {sup 3}P{sub 0} quark-antiquark creation model. This is also the case for the F/(F+D) ratios. Furthermore, the introduction of the zero helped to avoid the occurrence of unwanted bound states. Broken SU(3) symmetry serves to connect the NN and the YN channels, which leaves after fitting NN only a few free parameters for the determination of the YN interactions. In particular, the meson-baryon coupling constants are calculated via SU(3) using the coupling constants of the NN analysis as input. Here, as a novel feature, medium-strong flavor-symmetry breaking (FSB) of the coupling constants was allowed, using the {sup 3}P{sub 0} model with a Gell-Mann-Okubo hypercharge breaking for the BBM coupling. Very good fits for ESC model with and without FSB were obtained. The charge-symmetry breaking in the {lambda}p and {lambda}n channels, which is an SU(2

  4. Extended-soft-core baryon-baryon model. II. Hyperon-nucleon interaction

    NASA Astrophysics Data System (ADS)

    Rijken, Th. A.; Yamamoto, Y.

    2006-04-01

    The YN results are presented from the extended soft-core (ESC) interactions. They consist of local and nonlocal potentials because of (i) one-boson exchanges (OBE), which are the members of nonets of pseudoscalar, vector, scalar, and axial mesons; (ii) diffractive exchanges; (iii) two-pseudoscalar exchange; and (iv) meson-pair exchange (MPE). Both the OBE and pair vertices are regulated by Gaussian form factors producing potentials with a soft behavior near the origin. The assignment of the cutoff masses for the baryon-baryon-meson (BBM) vertices is dependent on the SU(3) classification of the exchanged mesons for OBE and a similar scheme for MPE. The particular version of the ESC model, called ESC04 [T. A. Rijken, Phys. Rev. C 73, 044007 (2006)], describes nucleon-nucleon (NN) and hyperon-nucleon (YN) interactions in a unified way using broken SU(3) symmetry. Novel ingredients are the inclusion of (i) the axial-vector meson potentials and (ii) a zero in the scalar- and axial-vector meson form factors. These innovations made it possible for the first time to keep the parameters of the model close to the predictions of the 3P0 quark-antiquark creation model. This is also the case for the F/(F+D) ratios. Furthermore, the introduction of the zero helped to avoid the occurrence of unwanted bound states. Broken SU(3) symmetry serves to connect the NN and the YN channels, which leaves after fitting NN only a few free parameters for the determination of the YN interactions. In particular, the meson-baryon coupling constants are calculated via SU(3) using the coupling constants of the NN analysis as input. Here, as a novel feature, medium-strong flavor-symmetry breaking (FSB) of the coupling constants was allowed, using the 3P0 model with a Gell-Mann-Okubo hypercharge breaking for the BBM coupling. Very good fits for ESC model with and without FSB were obtained. The charge-symmetry breaking in the Λp and Λn channels, which is an SU(2) isospin breaking, is included in the

  5. Use of RNA tertiary interaction modules for the crystallisation of the spliceosomal snRNP core domain.

    PubMed

    Leung, Adelaine K W; Kambach, Christian; Kondo, Yasushi; Kampmann, Martin; Jinek, Martin; Nagai, Kiyoshi

    2010-09-10

    RNA is known to perform diverse roles in the cell, often as ribonucleoprotein (RNP) particles. While the crystal structure of these RNP particles could provide crucial insights into their functions, crystallographic work on RNP complexes is often hampered by difficulties in obtaining well-diffracting crystals. The small nuclear ribonucleoprotein (snRNP) core domain, acting as an assembly nucleus for the maturation of snRNPs, plays a crucial role in the biogenesis of four of the spliceosomal snRNPs. We have succeeded in crystallising the human U4 snRNP core domain containing seven Sm proteins and a truncated U4 snRNA variant. The most critical factor in our success in the crystallisation was the introduction of various tertiary interaction modules into the RNA that could promote crystal packing without altering the core structure. Here, we describe various strategies employed in our crystallisation effort that could be applied to crystallisation of other RNP particles. PMID:20643141

  6. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles.

    PubMed

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-01-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications. PMID:27004738

  7. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    PubMed Central

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-01-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications. PMID:27004738

  8. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-03-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications.

  9. Interactions between RNA polymerase and the core recognition element are a determinant of transcription start site selection.

    PubMed

    Vvedenskaya, Irina O; Vahedian-Movahed, Hanif; Zhang, Yuanchao; Taylor, Deanne M; Ebright, Richard H; Nickels, Bryce E

    2016-05-24

    During transcription initiation, RNA polymerase (RNAP) holoenzyme unwinds ∼13 bp of promoter DNA, forming an RNAP-promoter open complex (RPo) containing a single-stranded transcription bubble, and selects a template-strand nucleotide to serve as the transcription start site (TSS). In RPo, RNAP core enzyme makes sequence-specific protein-DNA interactions with the downstream part of the nontemplate strand of the transcription bubble ("core recognition element," CRE). Here, we investigated whether sequence-specific RNAP-CRE interactions affect TSS selection. To do this, we used two next-generation sequencing-based approaches to compare the TSS profile of WT RNAP to that of an RNAP derivative defective in sequence-specific RNAP-CRE interactions. First, using massively systematic transcript end readout, MASTER, we assessed effects of RNAP-CRE interactions on TSS selection in vitro and in vivo for a library of 4(7) (∼16,000) consensus promoters containing different TSS region sequences, and we observed that the TSS profile of the RNAP derivative defective in RNAP-CRE interactions differed from that of WT RNAP, in a manner that correlated with the presence of consensus CRE sequences in the TSS region. Second, using 5' merodiploid native-elongating-transcript sequencing, 5' mNET-seq, we assessed effects of RNAP-CRE interactions at natural promoters in Escherichia coli, and we identified 39 promoters at which RNAP-CRE interactions determine TSS selection. Our findings establish RNAP-CRE interactions are a functional determinant of TSS selection. We propose that RNAP-CRE interactions modulate the position of the downstream end of the transcription bubble in RPo, and thereby modulate TSS selection, which involves transcription bubble expansion or transcription bubble contraction (scrunching or antiscrunching). PMID:27162333

  10. Pseudorevertants of a Semliki Forest Virus Fusion-Blocking Mutation Reveal a Critical Interchain Interaction in the Core Trimer▿

    PubMed Central

    Liu, Catherine Y.; Besanceney, Christen; Song, Yifan; Kielian, Margaret

    2010-01-01

    Semliki Forest virus (SFV) is an enveloped alphavirus that infects cells by a low-pH-triggered membrane fusion reaction mediated by the viral E1 protein. E1 inserts into target membranes and refolds to a hairpin-like homotrimer containing a central core trimer and an outer layer composed of domain III and the juxtamembrane stem region. The key residues involved in mediating E1 trimerization are not well understood. We recently showed that aspartate 188 in the interface of the core trimer plays a critical role. Substitution with lysine (D188K) blocks formation of the core trimer and E1 trimerization and strongly inhibits virus fusion and infection. Here, we have isolated and characterized revertants that rescued the fusion and growth defects of D188K. These revertants included pseudorevertants containing acidic or polar neutral residues at E1 position 188 and a second-site revertant containing an E1 K176T mutation. Computational analysis using multiconformation continuum electrostatics revealed an important interaction bridging D188 of one chain with K176 of the adjacent chain in the core trimer. E1 K176 is completely conserved among the alphaviruses, and mutations of K176 to threonine (K176T) or isoleucine (K176I) produced similar fusion phenotypes as D188 mutants. Together, our data support a model in which a ring of three salt bridges formed by D188 and K176 stabilize the core trimer, a key intermediate of the alphavirus fusion protein. PMID:20826687

  11. Study on some factors affecting the results in the use of MIP method in concrete research

    SciTech Connect

    Kumar, Rakesh; Bhattacharjee, B

    2003-03-01

    Effects of rate of pressure application and forms and type of sample on porosity and pore size distribution of concrete estimated through mercury intrusion porosimetry (MIP) are presented in this experimental work. Two different forms of concrete sample, namely, crushed chunks of concrete and small core drilled out from the concrete beam specimens, were used for this study. The results exhibit that the rate of pressure application in mercury porosimetry has little effect on porosity and pore size distribution of concrete. It is also demonstrated that small cores drilled out from large concrete specimens are preferable as samples for performing porosimetry test on concrete.

  12. Rubrene: The Interplay between Intramolecular and Intermolecular Interactions Determines the Planarization of Its Tetracene Core in the Solid State.

    PubMed

    Sutton, Christopher; Marshall, Michael S; Sherrill, C David; Risko, Chad; Brédas, Jean-Luc

    2015-07-15

    Rubrene is one of the most studied molecular semiconductors; its chemical structure consists of a tetracene backbone with four phenyl rings appended to the two central fused rings. Derivatization of these phenyl rings can lead to two very different solid-state molecular conformations and packings: One in which the tetracene core is planar and there exists substantive overlap among neighboring π-conjugated backbones; and another where the tetracene core is twisted and the overlap of neighboring π-conjugated backbones is completely disrupted. State-of-the-art electronic structure calculations show for all isolated rubrene derivatives that the twisted conformation is more favorable (by -1.7 to -4.1 kcal mol(-1)), which is a consequence of energetically unfavorable exchange-repulsion interactions among the phenyl side groups. Calculations based on available crystallographic structures reveal that planar conformations of the tetracene core in the solid state result from intermolecular interactions that can be tuned through well-chosen functionalization of the phenyl side groups and lead to improved intermolecular electronic couplings. Understanding the interplay of these intramolecular and intermolecular interactions provides insight into how to chemically modify rubrene and similar molecular semiconductors to improve the intrinsic materials electronic properties. PMID:26075966

  13. Interdependent nucleocytoplasmic trafficking and interactions of Dis3 with Rrp6, the core exosome and importin-alpha3.

    PubMed

    Graham, Amy C; Davis, Stephanie M; Andrulis, Erik D

    2009-05-01

    Subcellular compartmentalization of exoribonucleases (RNAses) is an important control mechanism in the temporal and spatial regulation of RNA processing and decay. Despite much progress towards understanding RNAse substrates and functions, we know little of how RNAses are transported and assembled into functional, subcellularly restricted complexes. To gain insight into this issue, we are studying the exosome-binding protein Dis3, a processive 3' to 5' exoribonuclease. Here, we examine the interactions and subcellular localization of the Drosophila melanogaster Dis3 (dDis3) protein. N-terminal domain mutants of dDis3 abolish associations with the 'core' exosome, yet only reduce binding to the 'nuclear' exosome-associated factor dRrp6. We show that nuclear localization of dDis3 requires a C-terminal classic nuclear localization signal (NLS). Consistent with this, dDis3 specifically co-precipitates the NLS-binding protein importin-alpha3. Surprisingly, dDis3 constructs that lack or mutate the C-terminal NLS retain importin-alpha3 binding, suggesting that the interaction is indirect. Finally, we find that endogenous dDis3 and dRrp6 exhibit coordinated nuclear enrichment or exclusion, suggesting that dDis3, Rrp6 and importin-alpha3 interact in a complex independent of the core. We propose that the movement and deposition of this complex is important for the subcellular compartmentalization and regulation of the exosome core. PMID:19220816

  14. Interdependent nucleocytoplasmic trafficking and interactions of Dis3 with Rrp6, the core exosome, and importin-α3

    PubMed Central

    Graham, Amy C.; Davis, Stephanie M.; Andrulis, Erik D.

    2009-01-01

    Subcellular compartmentalization of exoribonucleases (RNases) is an important control mechanism in the temporal and spatial regulation of RNA processing and decay. Despite much progress towards understanding RNase substrates and functions, we know little of how RNases are transported and assembled into functional, subcellularly-restricted complexes. To gain insight into this issue, we are studying the exosome-binding protein Dis3, a processive 3' to 5' exoribonuclease. Here, we examine the interactions and subcellular localization of the Drosophila melanogaster Dis3 (dDis3) protein. N-terminal domain mutants of dDis3 abolish associations with the `core' exosome yet only reduce binding to the `nuclear' exosome-associated factor dRrp6. We show that nuclear localization of dDis3 requires a C-terminal classic nuclear localization signal (NLS). Consistent with this, dDis3 specifically co-precipitates the NLS-binding protein importin-α3. Surprisingly, dDis3 constructs that lack or mutate the C-terminal NLS retain importin-α3 binding, suggesting that the interaction is indirect. Finally, we find that endogenous dDis3 and dRrp6 exhibit coordinated nuclear enrichment or exclusion, suggesting that dDis3, Rrp6, and importin-α3 interact in a complex independent of the core. We propose that the movement and deposition of this complex is important for the subcellular compartmentalization and regulation of the exosome core. PMID:19220816

  15. Vibronic structure and ion core interactions in Rydberg states of diazomethane: an experimental and theoretical investigation.

    PubMed

    Fedorov, Igor; Koziol, Lucas; Li, Guosheng; Reisler, Hanna; Krylov, Anna I

    2007-12-27

    Vibronic transitions to the 21A2(3py <-- pi) Rydberg state of CH2N2, CD2N2, and CHDN2 were recorded by 2 + 1 REMPI spectroscopy, and kinetic energy distributions (eKE) of photoelectrons from ionization of selected vibronic levels were determined by velocity map imaging. Normal-mode frequencies were obtained for the 21A2(3py) Rydberg state and for the cation. Mixed levels of the 21A2(3py) and 21B1(3pz) of the three isotopologs were identified by photoelectron imaging and analyzed. The equilibrium geometries and harmonic vibrational frequencies of the electronic states of neutral diazomethane were calculated by CCSD(T)/cc-pVTZ, and B3LYP/6-311G(2df,p). The latter method was also used to calculate isotope shifts for the ground-state neutral and cation. Geometry and frequencies of the ground state of the cation were calculated by CCSD(T)/cc-pVTZ, using the unrestricted (UHF) reference. The equilibrium structures, frequencies, and isotope shifts of the 21A2(3py) and 21B1(3pz) Rydberg states were calculated by EOM-EE-CCSD/6-311(3+,+)G(2df). In all cases where comparisons with experimental results were available, the agreement between theory and experiment was very good allowing a full analysis of trends in structure and vibrational frequencies in going from the neutral species to the excited Rydberg states, 21A2(3py) and 21B1(3pz), and the cation. Although the 21A2(3py) and 21B1(3pz) states have planar C2v symmetry like the ion, they exhibit differences in geometry due to the specific interactions of the electron in the 3py and 3pz orbitals with the nuclei charge distributions of the ion core. Moreover, trends in normal-mode frequencies in the ground states of the neutral and ion and the 21A2(3py) and 21B1(3pz) Rydberg states are consistent with removing an electron from the bonding piCN-orbital, which also has an antibonding character with respect to NN. To explain the observed trends, the vibrational modes are divided into two groups that involve displacements mainly

  16. Constraints on magma-wall rock thermal interaction during explosive eruptions from textural analysis of cored bombs

    NASA Astrophysics Data System (ADS)

    Sottili, G.; Taddeucci, J.; Palladino, D. M.

    2010-04-01

    Cored bombs, a kind of pyroclast consisting of a lithic core surrounded by a chilled shell of juvenile material, record the thermal interaction of magma with wall rocks. We performed textural analysis of cored bombs, solid-melt heat-transfer theoretical modelling, and high-temperature coating experiments to put temporal and intensity constraints on the thermal interaction of potassic magma feeder systems with carbonate wall rocks during explosive eruptions in the Quaternary, Colli Albani Volcanic District (Roman Province). It appears that the degree of thermal alteration of lithic cores records the duration of magma-core heat transfer, whereas the core/shell size ratio records the initial entrainment temperature of the lithic fragment. Both parameters appear to vary significantly with the eruptive style, magnitude and vent location. Specifically, small-scale (~ 0.1-1 km 3 DRE) hydromagmatic eruptions show magma-core heat-transfer durations of 0.1-10 s and entrainment temperatures in the range of 100-300 °C in the case of a monogenetic maar located in the Colli Albani peripheral area, while entrainment temperature is as high as to 800 °C for a polygenetic maar in a high-enthalpy geothermal system at the margins of the main Colli Albani magma chamber. A large-scale (~ 30 km 3 DRE) caldera-forming explosive event shows magma-core heat-transfer duration in the order of 10 2-10 3 s and temperature of 100-500 °C at the initial magma-wall rock contact. On these grounds, we derived the cooling rate of magmas as a function of the initial temperature, mass and size distribution of lithic clasts entrained. Magma cooling by lithic entrainment may have occurred on the same time-scale as that of eruptive pulses (seconds to hours), implying that lithic entrainment may effect changes in magma physico-chemical properties on a short time-scale and, consequently, affect eruptive conduit dynamics.

  17. Interaction of loading pattern and nuclear data uncertainties in reactor core calculations

    SciTech Connect

    Klein, M.; Gallner, L.; Krzykacz-Hausmann, B.; Pautz, A.; Velkov, K.; Zwermann, W.

    2012-07-01

    Along with best-estimate calculations for design and safety analysis, understanding uncertainties is important to determine appropriate design margins. In this framework, nuclear data uncertainties and their propagation to full core calculations are a critical issue. To deal with this task, different error propagation techniques, deterministic and stochastic are currently developed to evaluate the uncertainties in the output quantities. Among these is the sampling based uncertainty and sensitivity software XSUSA which is able to quantify the influence of nuclear data covariance on reactor core calculations. In the present work, this software is used to investigate systematically the uncertainties in the power distributions of two PWR core loadings specified in the OECD UAM-Benchmark suite. With help of a statistical sensitivity analysis, the main contributors to the uncertainty are determined. Using this information a method is studied with which loading patterns of reactor cores can be optimized with regard to minimizing power distribution uncertainties. It is shown that this technique is able to halve the calculation uncertainties of a MOX/UOX core configuration. (authors)

  18. Estimation of Concrete's Porosity by Ultrasounds

    NASA Astrophysics Data System (ADS)

    Benouis, A.; Grini, A.

    Durability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5 mm and 49.5 mm diameter and with 54 kHz frequency. Concrete specimens (160 mm diameter and 320 mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S + G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio.

  19. Size dependence of inter- and intra-cluster interactions in core-shell iron-iron oxide nanoclusters

    SciTech Connect

    Kaur, Maninder; McCloy, John S.; Jiang, Weilin; Yao, Qi; Qiang, You

    2012-06-15

    The room temperature magnetic properties of core-shell iron-iron oxide nanoclusters (NCs) synthesized by a cluster deposition system have been investigated, and their dependence on mean cluster size has been discussed. In this study, the surface/boundary spins of clusters were not frozen and were thermally activated during the measurements. The inter-cluster interactions between clusters and intra-cluster interactions between the iron core (ferromagnetic) and iron oxide shell (ferrimagnetic) have been investigated by field dependent isothermal remanent magnetization and dc demagnetization measurements at room temperature. The Henkel plot and delta M plot support the existence of dipolar inter-cluster interactions which become stronger with the growth of cluster size. The derivative of the initial magnetization curve implies that smaller clusters require less field and time than the bigger ones to overcome various energy barriers before aligning along the field direction. Coercive field and magnetization are also correlated with the interaction parameters. To compare the room temperature magnetic results, one system was studied at low temperature, where exchange coupling at the interface between the oxide and metallic phases was observed through bias effect and anisotropy enhancement.

  20. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues

    PubMed Central

    Ando, Hideaki; Hirose, Matsumi; Gainche, Laura; Kawaai, Katsuhiro; Bonneau, Benjamin; Ijuin, Takeshi; Itoh, Toshiki; Takenawa, Tadaomi; Mikoshiba, Katsuhiko

    2015-01-01

    Phosphatidylinositol phosphate kinases (PIPKs) are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate) is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα) and type IIα (PIPKIIα) in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3− cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5)P2. PMID:26509711

  1. Effect of attractive interactions on the water-like anomalies of a core-softened model potential.

    PubMed

    Pant, Shashank; Gera, Tarun; Choudhury, Niharendu

    2013-12-28

    It is now well established that water-like anomalies can be reproduced by a spherically symmetric potential with two length scales, popularly known as core-softened potential. In the present study we aim to investigate the effect of attractive interactions among the particles in a model fluid interacting with core-softened potential on the existence and location of various water-like anomalies in the temperature-pressure plane. We employ extensive molecular dynamic simulations to study anomalous nature of various order parameters and properties under isothermal compression. Order map analyses have also been done for all the potentials. We observe that all the systems with varying depth of attractive wells show structural, dynamic, and thermodynamic anomalies. As many of the previous studies involving model water and a class of core softened potentials have concluded that the structural anomaly region encloses the diffusion anomaly region, which in turn, encloses the density anomaly region, the same pattern has also been observed in the present study for the systems with less depth of attractive well. For the systems with deeper attractive well, we observe that the diffusion anomaly region shifts toward higher densities and is not always enclosed by the structural anomaly region. Also, density anomaly region is not completely enclosed by diffusion anomaly region in this case. PMID:24387380

  2. Effect of attractive interactions on the water-like anomalies of a core-softened model potential

    SciTech Connect

    Pant, Shashank; Gera, Tarun; Choudhury, Niharendu E-mail: niharc2002@yahoo.com

    2013-12-28

    It is now well established that water-like anomalies can be reproduced by a spherically symmetric potential with two length scales, popularly known as core-softened potential. In the present study we aim to investigate the effect of attractive interactions among the particles in a model fluid interacting with core-softened potential on the existence and location of various water-like anomalies in the temperature-pressure plane. We employ extensive molecular dynamic simulations to study anomalous nature of various order parameters and properties under isothermal compression. Order map analyses have also been done for all the potentials. We observe that all the systems with varying depth of attractive wells show structural, dynamic, and thermodynamic anomalies. As many of the previous studies involving model water and a class of core softened potentials have concluded that the structural anomaly region encloses the diffusion anomaly region, which in turn, encloses the density anomaly region, the same pattern has also been observed in the present study for the systems with less depth of attractive well. For the systems with deeper attractive well, we observe that the diffusion anomaly region shifts toward higher densities and is not always enclosed by the structural anomaly region. Also, density anomaly region is not completely enclosed by diffusion anomaly region in this case.

  3. A dimer of BPV-1 E2 containing a protease resistant core interacts with its DNA target.

    PubMed

    Dostatni, N; Thierry, F; Yaniv, M

    1988-12-01

    The E2 proteins encoded by papillomaviruses interact with the viral DNA to regulate its transcription. In the present study, we have constructed bacterial vectors expressing the full-length or N-terminal truncated BPV-1 E2 proteins under the control of an inducible promoter. By UV cross-linking experiments we show that a dimer of the intact or truncated E2 protein interacts with a single palindromic site ACCGNNNNCGGT. The DNA-binding domain of E2 can be reduced to a small protease resistant core. Methylation interference studies show that this C-terminal domain interacts with the major groove of the DNA by contacting two consecutive guanine residues in both halves of the palindrome. Although one binding site is sufficient for high affinity binding in vitro or in vivo, two E2 binding sites are required for transcriptional activation in eukaryotic cells. PMID:2850174

  4. Expansion dynamics in a one-dimensional hard-core boson model with three-body interactions

    PubMed Central

    Ren, Jie; Wu, Yin-Zhong; Xu, Xue-Fen

    2015-01-01

    Using the adaptive time-dependent density matrix renormalization group method, we numerically investigate the expansion dynamics of bosons in a one-dimensional hard-core boson model with three-body interactions. It is found that the bosons expand ballistically with weak interaction, which are obtained by local density and the radius Rn. It is shown that the expansion velocity V, obtained from Rn = Vt, is dependent on the number of bosons. As a prominent result, the expansion velocity decreases with the enhancement of three-body interaction. We further study the dynamics of the system, which quenches from the ground state with two-thirds filling, the results indicate the expansion is also ballistic in the gapless phase regime. It could help us detect the phase transition in the system. PMID:26435319

  5. A dimer of BPV-1 E2 containing a protease resistant core interacts with its DNA target.

    PubMed Central

    Dostatni, N; Thierry, F; Yaniv, M

    1988-01-01

    The E2 proteins encoded by papillomaviruses interact with the viral DNA to regulate its transcription. In the present study, we have constructed bacterial vectors expressing the full-length or N-terminal truncated BPV-1 E2 proteins under the control of an inducible promoter. By UV cross-linking experiments we show that a dimer of the intact or truncated E2 protein interacts with a single palindromic site ACCGNNNNCGGT. The DNA-binding domain of E2 can be reduced to a small protease resistant core. Methylation interference studies show that this C-terminal domain interacts with the major groove of the DNA by contacting two consecutive guanine residues in both halves of the palindrome. Although one binding site is sufficient for high affinity binding in vitro or in vivo, two E2 binding sites are required for transcriptional activation in eukaryotic cells. Images PMID:2850174

  6. An Investigation of Tendon Corrosion-Inhibitor Leakage into Concrete

    SciTech Connect

    Costello, J.F.; Naus, D.J.; Oland, C.B.

    1999-07-05

    During inspections performed at US nuclear power plants several years ago, some of the prestressed concrete containment had experienced leakage of the tendon sheathing filler. A study was conducted to indicate the extent of the leakage into the concrete and its potential effects on concrete properties. Concrete core samples were obtained from the Trojan Nuclear Plant. Examination and testing of the core samples indicated that the appearance of tendon sheathing filler on the surface was due to leakage of the filler from the conduits and its subsequent migration to the concrete surface through cracks that were present. Migration of the tendon sheathing filler was confined to the cracks with no perceptible movement into the concrete. Results of compressive strength tests indicated that the concrete quality was consistent in the containment and that the strength had increased relative to the strength at 28 days age.

  7. Physical Interactions and Functional Coordination between the Core Subunits of Set1/Mll Complexes and the Reprogramming Factors

    PubMed Central

    Yang, Zhenhua; Augustin, Jonathan; Hu, Jing; Jiang, Hao

    2015-01-01

    Differentiated cells can be reprogrammed to the pluripotent state by overexpression of defined factors, and this process is profoundly influenced by epigenetic mechanisms including dynamic histone modifications. Changes in H3K4 methylation have been shown to be the predominant activating response in the early stage of cellular reprogramming. Mechanisms underlying such epigenetic priming, however, are not well understood. Here we show that the expression of the reprogramming factors (Yamanaka factors, Oct4, Sox2, Klf4 and Myc), especially Myc, directly promotes the expression of certain core subunits of the Set1/Mll family of H3K4 methyltransferase complexes. A dynamic recruitment of the Set1/Mll complexes largely, though not sufficiently in its own, explains the dynamics of the H3K4 methylation during cellular reprogramming. We then demonstrate that the core subunits of the Set1/Mll complexes physically interact with mainly Sox2 and Myc among the Yamanaka factors. We further show that Sox2 directly binds the Ash2l subunit in the Set1/Mll complexes and this binding is mediated by the HMG domain of Sox2. Functionally, we show that the Set1/Mll complex core subunits are required for efficient cellular reprogramming. We also show that Dpy30, one of the core subunits in the complexes, is required for the efficient target binding of the reprogramming factors. Interestingly, such requirement is not necessarily dependent on locus-specific H3K4 methylation. Our work provides a better understanding of how the reprogramming factors physically interact and functionally coordinate with a key group of epigenetic modulators to mediate transitions of the chromatin state involved in cellular reprogramming. PMID:26691508

  8. Physical Interactions and Functional Coordination between the Core Subunits of Set1/Mll Complexes and the Reprogramming Factors.

    PubMed

    Yang, Zhenhua; Augustin, Jonathan; Hu, Jing; Jiang, Hao

    2015-01-01

    Differentiated cells can be reprogrammed to the pluripotent state by overexpression of defined factors, and this process is profoundly influenced by epigenetic mechanisms including dynamic histone modifications. Changes in H3K4 methylation have been shown to be the predominant activating response in the early stage of cellular reprogramming. Mechanisms underlying such epigenetic priming, however, are not well understood. Here we show that the expression of the reprogramming factors (Yamanaka factors, Oct4, Sox2, Klf4 and Myc), especially Myc, directly promotes the expression of certain core subunits of the Set1/Mll family of H3K4 methyltransferase complexes. A dynamic recruitment of the Set1/Mll complexes largely, though not sufficiently in its own, explains the dynamics of the H3K4 methylation during cellular reprogramming. We then demonstrate that the core subunits of the Set1/Mll complexes physically interact with mainly Sox2 and Myc among the Yamanaka factors. We further show that Sox2 directly binds the Ash2l subunit in the Set1/Mll complexes and this binding is mediated by the HMG domain of Sox2. Functionally, we show that the Set1/Mll complex core subunits are required for efficient cellular reprogramming. We also show that Dpy30, one of the core subunits in the complexes, is required for the efficient target binding of the reprogramming factors. Interestingly, such requirement is not necessarily dependent on locus-specific H3K4 methylation. Our work provides a better understanding of how the reprogramming factors physically interact and functionally coordinate with a key group of epigenetic modulators to mediate transitions of the chromatin state involved in cellular reprogramming. PMID:26691508

  9. Sensitivity of the geomagnetic axial dipole to thermal core-mantle interactions

    PubMed

    Bloxham

    2000-05-01

    Since the work of William Gilbert in 1600 (ref. 1), it has been widely believed that the Earth's magnetic field, when suitably time-averaged, is that of a magnetic dipole positioned at the Earth's centre and aligned with the rotational axis. This 'geocentric axial dipole' (GAD) hypothesis has been the central model for the study of the Earth's magnetic field--it underpins almost all interpretations of palaeomagnetic data, whether for studies of palaeomagnetic secular variation, for plate tectonic reconstructions, or for studies of palaeoclimate. Although the GAD hypothesis appears to provide a good description of the Earth's magnetic field over at least the past 100 Myr (ref. 2), it is difficult to test the hypothesis for earlier periods, and there is some evidence that a more complicated model is required for the period before 250 Myr ago. Kent and Smethurst suggested that this additional complexity might be because the inner core would have been smaller at that time. Here I use a numerical geodynamo model and find that reducing the size of the inner core does not significantly change the character of the magnetic field. I also consider an alternative process that could lead to the breakdown of the GAD hypothesis on this timescale, the evolution of heat-flux variations at the core-mantle boundary, induced by mantle convection. I find that a simple pattern of heat-flux variations at the core-mantle boundary, which is plausible for times before the Mesozoic era, results in a strong octupolar contribution to the field, consistent with previous findings. PMID:10811217

  10. Sensitivity of the geomagnetic axial dipole to thermal core-mantle interactions

    NASA Astrophysics Data System (ADS)

    Bloxham, Jeremy

    2000-05-01

    Since the work of William Gilbert in 1600 (ref. 1), it has been widely believed that the Earth's magnetic field, when suitably time-averaged, is that of a magnetic dipole positioned at the Earth's centre and aligned with the rotational axis. This `geocentric axial dipole' (GAD) hypothesis has been the central model for the study of the Earth's magnetic field-it underpins almost all interpretations of palaeomagnetic data, whether for studies of palaeomagnetic secular variation, for plate tectonic reconstructions, or for studies of palaeoclimate. Although the GAD hypothesis appears to provide a good description of the Earth's magnetic field over at least the past 100Myr (ref. 2), it is difficult to test the hypothesis for earlier periods, and there is some evidence that a more complicated model is required for the period before 250Myr ago. Kent and Smethurst suggested that this additional complexity might be because the inner core would have been smaller at that time. Here I use a numerical geodynamo model and find that reducing the size of the inner core does not significantly change the character of the magnetic field. I also consider an alternative process that could lead to the breakdown of the GAD hypothesis on this timescale, the evolution of heat-flux variations at the core-mantle boundary, induced by mantle convection. I find that a simple pattern of heat-flux variations at the core-mantle boundary, which is plausible for times before the Mesozoic era, results in a strong octupolar contribution to the field, consistent with previous findings.

  11. Well-defined oxide core-polymer shell nanoparticles: interfacial interactions, peculiar dynamics, and transitions in polymer nanolayers.

    PubMed

    Bershtein, V A; Gun'ko, V M; Egorova, L M; Guzenko, N V; Pakhlov, E M; Ryzhov, V A; Zarko, V I

    2010-07-01

    Interfacial interactions, chain dynamics, and glass and melting transitions were studied in well-defined core-shell nanoparticles with amorphous silica or crystalline alumina cores and noncrystallizable poly(vinyl pyrrolidone) (PVP) or crystallizable poly(ethylene glycol) (PEG) shells. Varying particle composition caused regular changes in the shell thickness from 1 to 2 nm (monomolecular layer) up to 90 nm. Far- and mid-IR spectroscopy allowed us to register hydrogen bonding and, tentatively, Lewis/Brønsted (LB) interfacial interactions as well as changes in the dynamics and conformational state of the polymer chains as a function of the nanoshell thickness. Their most pronounced peculiarities were found for the monomolecular polymer layers. The LB interactions were stronger with the alumina substrate than silica. DSC analysis was performed, and the data obtained were in agreement with the spectroscopic data. Unlike the bulk polymer, the PVP monolayer was characterized with an extraordinarily large dynamic heterogeneity within the glass transition while broadening the transition range and varying the activation energy by an order of magnitude. The PEG monolayer adsorbed on silica was totally amorphous, whereas a highly crystalline one with the anomalously thin lamellae, down to 3 nm thick, was adsorbed on an alumina surface, presumably as a result of the quasi-heteroepitaxial crystallization process. PMID:20415443

  12. A transient analysis of decomposition and erosion of concrete exposed to a surface heat flux

    SciTech Connect

    Kilic, A.N. . Nuclear Engineering Dept.)

    1994-12-01

    A simple approximation for predicting the concrete erosion rate and depth is derived based on the heat balance integral method for conduction with the time-dependent boundary conditions. The problem is considered a four-region model including separate, moving heat sinks at the boundaries due to endothermic decomposition reactions. Polynomial temperature profiles are assumed, and the results are compared with previous experimental data and other analytical solutions. Since the technique provides an approximate temperature distribution on the average, it does not give the real temperature evaluation but provides a simple prediction of the erosion rates and the depth of defaulted concrete in terms of the parameters that are important during the physical phenomena. Because of its simplicity and reliability, the model might be useful for the larger molten core/concrete interaction codes and aerosol generation models.

  13. Low-amplitude magnetic vortex core reversal by non-linear interaction between azimuthal spin waves and the vortex gyromode

    SciTech Connect

    Sproll, Markus; Noske, Matthias; Kammerer, Matthias; Dieterle, Georg; Weigand, Markus; Stoll, Hermann; Schütz, Gisela; Bauer, Hans; Gangwar, Ajay; Woltersdorf, Georg; Back, Christian H.

    2014-01-06

    We show, by experiments and micromagnetic simulations in vortex structures, that an active “dual frequency” excitation of both the sub-GHz vortex gyromode and multi-GHz spin waves considerably changes the frequency response of spin wave mediated vortex core reversal. Besides additional minima in the switching threshold, a significant broadband reduction of the switching amplitudes is observed, which can be explained by non-linear interaction between the vortex gyromode and the spin waves. We conclude that the well known frequency spectra of azimuthal spin waves in vortex structures are altered substantially, when the vortex gyromode is actively excited simultaneously.

  14. Pleiohomeotic Interacts with the Core Transcription Elongation Factor Spt5 to Regulate Gene Expression in Drosophila

    PubMed Central

    Jennings, Barbara H.

    2013-01-01

    The early elongation checkpoint regulated by Positive Transcription Elongation Factor b (P-TEFb) is a critical control point for the expression of many genes. Spt5 interacts directly with RNA polymerase II and has an essential role in establishing this checkpoint, and also for further transcript elongation. Here we demonstrate that Drosophila Spt5 interacts both physically and genetically with the Polycomb Group (PcG) protein Pleiohomeotic (Pho), and the majority of Pho binding sites overlap with Spt5 binding sites across the genome in S2 cells. Our results indicate that Pho can interact with Spt5 to regulate transcription elongation in a gene specific manner. PMID:23894613

  15. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  16. Refractory concretes

    DOEpatents

    Holcombe, Jr., Cressie E.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 with an aqueous solution of a salt selected from the group of NH.sub.4 NO.sub.3, NH.sub.4 Cl, YCl.sub.3 and Mg(NO.sub.3).sub.2 to form a fluid mixture; and allowing the fluid mixture to harden.

  17. Penetration analysis of projectile with inclined concrete target

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Kim, H. W.; Yoo, Y. H.

    2015-09-01

    This paper presents numerical analysis result of projectile penetration with concrete target. We applied dynamic material properties of 4340 steels, aluminium and explosive for projectile body. Dynamic material properties were measured with static tensile testing machine and Hopkinson pressure bar tests. Moreover, we used three concrete damage models included in LS-DYNA 3D, such as SOIL_CONCRETE, CSCM (cap model with smooth interaction) and CONCRETE_DAMAGE (K&C concrete) models. Strain rate effect for concrete material is important to predict the fracture deformation and shape of concrete, and penetration depth for projectiles. CONCRETE_DAMAGE model with strain rate effect also applied to penetration analysis. Analysis result with CSCM model shows good agreement with penetration experimental data. The projectile trace and fracture shapes of concrete target were compared with experimental data.

  18. New Findings for Concreteness and Imagery Effects in Written Composition.

    ERIC Educational Resources Information Center

    Sadoski, Mark; Goetz, Ernest T.; Stricker, Andrew G.; Burdenski, Thomas K., Jr.

    2003-01-01

    Investigates the effects of word concreteness and either imagery, verbal, or control strategy instructions on the composition of written definitions. Reveals significant effects of word concreteness on several quantity and quality variables, but no significant effect of strategy instructions or interaction between concreteness and strategy…

  19. Aliphatic peptides show similar self-assembly to amyloid core sequences, challenging the importance of aromatic interactions in amyloidosis

    PubMed Central

    Lakshmanan, Anupama; Cheong, Daniel W.; Accardo, Angelo; Di Fabrizio, Enzo; Riekel, Christian; Hauser, Charlotte A. E.

    2013-01-01

    The self-assembly of abnormally folded proteins into amyloid fibrils is a hallmark of many debilitating diseases, from Alzheimer’s and Parkinson diseases to prion-related disorders and diabetes type II. However, the fundamental mechanism of amyloid aggregation remains poorly understood. Core sequences of four to seven amino acids within natural amyloid proteins that form toxic fibrils have been used to study amyloidogenesis. We recently reported a class of systematically designed ultrasmall peptides that self-assemble in water into cross-β–type fibers. Here we compare the self-assembly of these peptides with natural core sequences. These include core segments from Alzheimer’s amyloid-β, human amylin, and calcitonin. We analyzed the self-assembly process using circular dichroism, electron microscopy, X-ray diffraction, rheology, and molecular dynamics simulations. We found that the designed aliphatic peptides exhibited a similar self-assembly mechanism to several natural sequences, with formation of α-helical intermediates being a common feature. Interestingly, the self-assembly of a second core sequence from amyloid-β, containing the diphenylalanine motif, was distinctly different from all other examined sequences. The diphenylalanine-containing sequence formed β-sheet aggregates without going through the α-helical intermediate step, giving a unique fiber-diffraction pattern and simulation structure. Based on these results, we propose a simplified aliphatic model system to study amyloidosis. Our results provide vital insight into the nature of early intermediates formed and suggest that aromatic interactions are not as important in amyloid formation as previously postulated. This information is necessary for developing therapeutic drugs that inhibit and control amyloid formation. PMID:23267112

  20. Aliphatic peptides show similar self-assembly to amyloid core sequences, challenging the importance of aromatic interactions in amyloidosis.

    PubMed

    Lakshmanan, Anupama; Cheong, Daniel W; Accardo, Angelo; Di Fabrizio, Enzo; Riekel, Christian; Hauser, Charlotte A E

    2013-01-01

    The self-assembly of abnormally folded proteins into amyloid fibrils is a hallmark of many debilitating diseases, from Alzheimer's and Parkinson diseases to prion-related disorders and diabetes type II. However, the fundamental mechanism of amyloid aggregation remains poorly understood. Core sequences of four to seven amino acids within natural amyloid proteins that form toxic fibrils have been used to study amyloidogenesis. We recently reported a class of systematically designed ultrasmall peptides that self-assemble in water into cross-β-type fibers. Here we compare the self-assembly of these peptides with natural core sequences. These include core segments from Alzheimer's amyloid-β, human amylin, and calcitonin. We analyzed the self-assembly process using circular dichroism, electron microscopy, X-ray diffraction, rheology, and molecular dynamics simulations. We found that the designed aliphatic peptides exhibited a similar self-assembly mechanism to several natural sequences, with formation of α-helical intermediates being a common feature. Interestingly, the self-assembly of a second core sequence from amyloid-β, containing the diphenylalanine motif, was distinctly different from all other examined sequences. The diphenylalanine-containing sequence formed β-sheet aggregates without going through the α-helical intermediate step, giving a unique fiber-diffraction pattern and simulation structure. Based on these results, we propose a simplified aliphatic model system to study amyloidosis. Our results provide vital insight into the nature of early intermediates formed and suggest that aromatic interactions are not as important in amyloid formation as previously postulated. This information is necessary for developing therapeutic drugs that inhibit and control amyloid formation. PMID:23267112

  1. Anticancer drug mithramycin interacts with core histones: An additional mode of action of the DNA groove binder

    PubMed Central

    Banerjee, Amrita; Sanyal, Sulagna; Kulkarni, Kirti K.; Jana, Kuladip; Roy, Siddhartha; Das, Chandrima; Dasgupta, Dipak

    2014-01-01

    Mithramycin (MTR) is a clinically approved DNA-binding antitumor antibiotic currently in Phase 2 clinical trials at National Institutes of Health for treatment of osteosarcoma. In view of the resurgence in the studies of this generic antibiotic as a human medicine, we have examined the binding properties of MTR with the integral component of chromatin – histone proteins – as a part of our broad objective to classify DNA-binding molecules in terms of their ability to bind chromosomal DNA alone (single binding mode) or both histones and chromosomal DNA (dual binding mode). The present report shows that besides DNA, MTR also binds to core histones present in chromatin and thus possesses the property of dual binding in the chromatin context. In contrast to the MTR–DNA interaction, association of MTR with histones does not require obligatory presence of bivalent metal ion like Mg2+. As a consequence of its ability to interact with core histones, MTR inhibits histone H3 acetylation at lysine 18, an important signature of active chromatin, in vitro and ex vivo. Reanalysis of microarray data of Ewing sarcoma cell lines shows that upon MTR treatment there is a significant down regulation of genes, possibly implicating a repression of H3K18Ac-enriched genes apart from DNA-binding transcription factors. Association of MTR with core histones and its ability to alter post-translational modification of histone H3 clearly indicates an additional mode of action of this anticancer drug that could be implicated in novel therapeutic strategies. PMID:25473595

  2. Self-Propelled Particles with Soft-Core Interactions: Patterns, Stability, and Collapse

    NASA Astrophysics Data System (ADS)

    D'Orsogna, M. R.; Chuang, Y. L.; Bertozzi, A. L.; Chayes, L. S.

    2006-03-01

    Understanding collective properties of driven particle systems is significant for naturally occurring aggregates and because the knowledge gained can be used as building blocks for the design of artificial ones. We model self-propelling biological or artificial individuals interacting through pairwise attractive and repulsive forces. For the first time, we are able to predict stability and morphology of organization starting from the shape of the two-body interaction. We present a coherent theory, based on fundamental statistical mechanics, for all possible phases of collective motion.

  3. Self-propelled particles with soft-core interactions: patterns, stability, and collapse.

    PubMed

    D' Orsogna, M R; Chuang, Y L; Bertozzi, A L; Chayes, L S

    2006-03-17

    Understanding collective properties of driven particle systems is significant for naturally occurring aggregates and because the knowledge gained can be used as building blocks for the design of artificial ones. We model self-propelling biological or artificial individuals interacting through pairwise attractive and repulsive forces. For the first time, we are able to predict stability and morphology of organization starting from the shape of the two-body interaction. We present a coherent theory, based on fundamental statistical mechanics, for all possible phases of collective motion. PMID:16605738

  4. Evidence of exchange bias effect originating from the interaction between antiferromagnetic core and spin glass shell

    SciTech Connect

    Zhang, X. K. Yuan, J. J.; Yu, H. J.; Zhu, X. R.; Xie, Y. M.; Tang, S. L.; Xu, L. Q.

    2014-07-14

    Spin glass behavior and exchange bias effect have been observed in antiferromagnetic SrMn{sub 3}O{sub 6−x} nanoribbons synthesized via a self-sacrificing template process. The magnetic field dependence of thermoremanent magnetization and isothermal remanent magnetization shows that the sample is good correspondence to spin glass and diluted antiferromagnetic system for the applied field H < 2 T and H > 2 T, respectively. By detailed analysis of training effect using Binek's model, we argue that the observed exchange bias effect in SrMn{sub 3}O{sub 6−x} nanoribbons arises entirely from an interface exchange coupling between the antiferromagnetic core and spin glass shell. The present study is useful for understanding the nature of shell layer and the origin of exchange bias effect in other antiferromagnetic nanosystems as well.

  5. Evidence of exchange bias effect originating from the interaction between antiferromagnetic core and spin glass shell

    NASA Astrophysics Data System (ADS)

    Zhang, X. K.; Tang, S. L.; Xu, L. Q.; Yuan, J. J.; Yu, H. J.; Zhu, X. R.; Xie, Y. M.

    2014-07-01

    Spin glass behavior and exchange bias effect have been observed in antiferromagnetic SrMn3O6-x nanoribbons synthesized via a self-sacrificing template process. The magnetic field dependence of thermoremanent magnetization and isothermal remanent magnetization shows that the sample is good correspondence to spin glass and diluted antiferromagnetic system for the applied field H < 2 T and H > 2 T, respectively. By detailed analysis of training effect using Binek's model, we argue that the observed exchange bias effect in SrMn3O6-x nanoribbons arises entirely from an interface exchange coupling between the antiferromagnetic core and spin glass shell. The present study is useful for understanding the nature of shell layer and the origin of exchange bias effect in other antiferromagnetic nanosystems as well.

  6. Concrete Materials and Structures

    SciTech Connect

    Wilby, C.B.

    1991-12-31

    Concrete Materials and Structures provides one of the most comprehensive treatments on the topic of concrete engineering. The author covers a gamut of concrete subjects ranging from concrete mix design, basic reinforced concrete theory, prestressed concrete, shell roofs, and two-way slabs-including a through presentation of Hillerborg`s strip method. Prior to Wilby`s book, the scope of these topics would require at least four separate books to cover. With this new book he has succeeded, quite remarkably, in condensing a fairly complete knowledge of concrete engineering into one single easy-to-carry volume.

  7. Polymer concrete patching manual

    NASA Astrophysics Data System (ADS)

    Fontana, J. J.; Bartholomew, J.

    1982-06-01

    The practicality of using polymer concrete to repair deteriorated portland cement concrete bridge decks and pavements was demonstrated. This manual outlines the procedures for using polymer concrete as a rapid patching material to repair deteriorated concrete. The process technology, materials, equipment, and safety provisions used in manufacturing and placing polymer concrete are discussed. Potential users are informed of the various steps necessary to insure successful field applications of the material.

  8. Metamorphosis of SN 2014C: Delayed Interaction between a Hydrogen Poor Core-collapse Supernova and a Nearby Circumstellar Shell

    NASA Astrophysics Data System (ADS)

    Milisavljevic, D.; Margutti, R.; Kamble, A.; Patnaude, D. J.; Raymond, J. C.; Eldridge, J. J.; Fong, W.; Bietenholz, M.; Challis, P.; Chornock, R.; Drout, M. R.; Fransson, C.; Fesen, R. A.; Grindlay, J. E.; Kirshner, R. P.; Lunnan, R.; Mackey, J.; Miller, G. F.; Parrent, J. T.; Sanders, N. E.; Soderberg, A. M.; Zauderer, B. A.

    2015-12-01

    We present optical observations of supernova SN 2014C, which underwent an unprecedented slow metamorphosis from H-poor type Ib to H-rich type IIn over the course of one year. The observed spectroscopic evolution is consistent with the supernova having exploded in a cavity before encountering a massive shell of the progenitor star's stripped hydrogen envelope. Possible origins for the circumstellar shell include a brief Wolf-Rayet fast wind phase that overtook a slower red supergiant wind, eruptive ejection, or confinement of circumstellar material by external influences of neighboring stars. An extended high velocity Hα absorption feature seen in near-maximum light spectra implies that the progenitor star was not completely stripped of hydrogen at the time of core collapse. Archival pre-explosion Subaru Telescope Suprime-Cam and Hubble Space Telescope Wide Field Planetary Camera 2 images of the region obtained in 2009 show a coincident source that is most likely a compact massive star cluster in NGC 7331 that hosted the progenitor system. By comparing the emission properties of the source with stellar population models that incorporate interacting binary stars we estimate the age of the host cluster to be 30-300 Myr, and favor ages closer to 30 Myr in light of relatively strong Hα emission. SN 2014C is the best observed member of a class of core-collapse supernovae that fill the gap between events that interact strongly with dense, nearby environments immediately after explosion and those that never show signs of interaction. Better understanding of the frequency and nature of this intermediate population can contribute valuable information about the poorly understood final stages of stellar evolution.

  9. Experimental characterization of cement-bentonite interaction using core infiltration techniques and 4D computed tomography

    NASA Astrophysics Data System (ADS)

    Dolder, F.; Mäder, U.; Jenni, A.; Schwendener, N.

    Deep geological storage of radioactive waste foresees cementitious materials as reinforcement of tunnels and as backfill. Bentonite is proposed to enclose spent fuel drums, and as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water composition that drives diffusive solute transport. Laboratory studies and reactive transport modeling predict significant mineral alteration at and near interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of this project is to characterize and quantify the cement/bentonite skin effects spatially and temporally in laboratory experiments. A newly developed mobile X-ray transparent core infiltration device was used, which allows performing X-ray computed tomography (CT) periodically without interrupting a running experiment. A pre-saturated cylindrical MX-80 bentonite sample (1920 kg/m3 average wet density) is subjected to a confining pressure as a constant total pressure boundary condition. The infiltration of a hyperalkaline (pH 13.4), artificial OPC (ordinary Portland cement) pore water into the bentonite plug alters the mineral assemblage over time as an advancing reaction front. The related changes in X-ray attenuation values are related to changes in phase densities, porosity and local bulk density and are tracked over time periodically by non-destructive CT scans. Mineral precipitation is observed in the inflow filter. Mineral alteration in the first millimeters of the bentonite sample is clearly detected and the reaction front is presently progressing with an average linear velocity that is 8 times slower than that for anions. The reaction zone is characterized by a higher X-ray attenuation compared to the signal of the pre-existing mineralogy. Chemical analysis of the outflow fluid showed initially elevated anion and cation concentrations compared to the infiltration fluid due to anion exclusion effects related to compaction of

  10. Ex-Vessel Core Melt Modeling Comparison between MELTSPREAD-CORQUENCH and MELCOR 2.1

    SciTech Connect

    Robb, Kevin R.; Farmer, Mitchell; Francis, Matthew W.

    2014-03-01

    System-level code analyses by both United States and international researchers predict major core melting, bottom head failure, and corium-concrete interaction for Fukushima Daiichi Unit 1 (1F1). Although system codes such as MELCOR and MAAP are capable of capturing a wide range of accident phenomena, they currently do not contain detailed models for evaluating some ex-vessel core melt behavior. However, specialized codes containing more detailed modeling are available for melt spreading such as MELTSPREAD as well as long-term molten corium-concrete interaction (MCCI) and debris coolability such as CORQUENCH. In a preceding study, Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Melt Spreading and Core-Concrete Interaction Analyses with MELTSPREAD and CORQUENCH, the MELTSPREAD-CORQUENCH codes predicted the 1F1 core melt readily cooled in contrast to predictions by MELCOR. The user community has taken notice and is in the process of updating their systems codes; specifically MAAP and MELCOR, to improve and reduce conservatism in their ex-vessel core melt models. This report investigates why the MELCOR v2.1 code, compared to the MELTSPREAD and CORQUENCH 3.03 codes, yield differing predictions of ex-vessel melt progression. To accomplish this, the differences in the treatment of the ex-vessel melt with respect to melt spreading and long-term coolability are examined. The differences in modeling approaches are summarized, and a comparison of example code predictions is provided.

  11. Distinct interacting core taxa in co-occurrence networks enable discrimination of polymicrobial oral diseases with similar symptoms.

    PubMed

    Shiba, Takahiko; Watanabe, Takayasu; Kachi, Hirokazu; Koyanagi, Tatsuro; Maruyama, Noriko; Murase, Kazunori; Takeuchi, Yasuo; Maruyama, Fumito; Izumi, Yuichi; Nakagawa, Ichiro

    2016-01-01

    Polymicrobial diseases, which can be life threatening, are caused by the presence and interactions of multiple microbes. Peri-implantitis and periodontitis are representative polymicrobial diseases that show similar clinical symptoms. To establish a means of differentiating between them, we compared microbial species and functional genes in situ by performing metatranscriptomic analyses of peri-implantitis and periodontitis samples obtained from the same subjects (n = 12 each). Although the two diseases differed in terms of 16S rRNA-based taxonomic profiles, they showed similarities with respect to functional genes and taxonomic and virulence factor mRNA profiles. The latter-defined as microbial virulence types-differed from those of healthy periodontal sites. We also showed that networks based on co-occurrence relationships of taxonomic mRNA abundance (co-occurrence networks) were dissimilar between the two diseases. Remarkably, these networks consisted mainly of taxa with a high relative mRNA-to-rRNA ratio, with some showing significant co-occurrence defined as interacting core taxa, highlighting differences between the two groups. Thus, peri-implantitis and periodontitis have shared as well as distinct microbiological characteristics. Our findings provide insight into microbial interactions in polymicrobial diseases with unknown etiologies. PMID:27499042

  12. Distinct interacting core taxa in co-occurrence networks enable discrimination of polymicrobial oral diseases with similar symptoms

    PubMed Central

    Shiba, Takahiko; Watanabe, Takayasu; Kachi, Hirokazu; Koyanagi, Tatsuro; Maruyama, Noriko; Murase, Kazunori; Takeuchi, Yasuo; Maruyama, Fumito; Izumi, Yuichi; Nakagawa, Ichiro

    2016-01-01

    Polymicrobial diseases, which can be life threatening, are caused by the presence and interactions of multiple microbes. Peri-implantitis and periodontitis are representative polymicrobial diseases that show similar clinical symptoms. To establish a means of differentiating between them, we compared microbial species and functional genes in situ by performing metatranscriptomic analyses of peri-implantitis and periodontitis samples obtained from the same subjects (n = 12 each). Although the two diseases differed in terms of 16S rRNA-based taxonomic profiles, they showed similarities with respect to functional genes and taxonomic and virulence factor mRNA profiles. The latter—defined as microbial virulence types—differed from those of healthy periodontal sites. We also showed that networks based on co-occurrence relationships of taxonomic mRNA abundance (co-occurrence networks) were dissimilar between the two diseases. Remarkably, these networks consisted mainly of taxa with a high relative mRNA-to-rRNA ratio, with some showing significant co-occurrence defined as interacting core taxa, highlighting differences between the two groups. Thus, peri-implantitis and periodontitis have shared as well as distinct microbiological characteristics. Our findings provide insight into microbial interactions in polymicrobial diseases with unknown etiologies. PMID:27499042

  13. From the pore scale to the core scale: How to model the spatial interactions in soils?

    NASA Astrophysics Data System (ADS)

    Garnier, Patricia; Pot, Valerie; Monga, Oivier; Chenu, Claire; Vieuble-Gonod, Laurent; Vogel, Laure; Nunan, Naoise; Otten, Wilfried; Baveye, Philippe

    2015-04-01

    Recently, innovative modeling tools have been developed to describe the physico-chemical processes occurring in soil pores at scales directly relevant to microorganisms. Modelling efforts have attempted to understand how microbial processes such as decomposition or competition among species are affected by diffusion in 2-D or 3-D environments. Most of these models use a virtual representative pore network that can have the same features as soil pores with regular lattice grid. The most recent and innovative of these models use real images of soil structure from binarized 3D images. These models are able to simulate microbial degradation although microorganisms and organic matter are placed at different locations in the pore space. Then, the encounter of nutrients and microorganisms is achieved through the implementation of the diffusion process of the soluble substrates in the connected water-filled space. The high computational demand of this type of approach restricts its applicability to small-scale systems, typically in the order of micrometers or millimeters. The numerical techniques used to solve the equations include the lattice Boltzmann method, algorithmic methods and finite element methods. Most of these models have not yet been tested with experimental data because of the difficulties of investigating such small scales. On the other hand, many experimental results developed at the core scale have showed the importance of soil microbial habitat and especially how physical characteristics (pore sizes, connectivity) control the decomposition of organic substrates via their accessibility by microorganisms. The general question we have now to answer is whether information on the spatial heterogeneity of soils at the microscale can be used to predict the processes observed at the macroscale in soils

  14. On the interaction of alginate-based core-shell nanocarriers with keratinocytes in vitro.

    PubMed

    Nguyen, Hoang Truc Phuong; Allard-Vannier, Emilie; Gaillard, Cédric; Eddaoudi, Imane; Miloudi, Lynda; Soucé, Martin; Chourpa, Igor; Munnier, Emilie

    2016-06-01

    Calcium alginate nanocarriers (CaANCs) were developed as a potential tool for delivery of hydrophobic active molecules such as pharmaceutical and cosmetic active ingredients. In this study, we focused on interactions between CaANCs and keratinocytes in culture and examined toxicity, internalization and drug release. Prior to cellular interactions, cryogenic transmission electron microscopy images showed that CaANCs appear as regular, spherical and dense particles, giving evidence of the surface gelation of CaANCs. Their size, around 200nm, was stable under tested conditions (temperature, culture media, presence of serum and presence of encapsulated dye), and their toxicity on keratinocytes was very low. Flow cytometry assays showed that CaANCs are internalized into keratinocytes by endocytosis with a predominant implication of the caveolae-mediated route. Förster resonance energy transfer (FRET) demonstrated that after a 2h contact, the release of CaANC contents in the cytoplasm of keratinocytes was almost complete. The endocytosis of CaANCs by a lysosome-free pathway, and the rapid release of their contents inside keratinocytes, will allow vectorized molecules to fully exhibit their pharmacological or cosmetic activity. PMID:26962764

  15. The structure of the core NuRD repression complex provides insights into its interaction with chromatin

    PubMed Central

    Millard, Christopher J; Varma, Niranjan; Saleh, Almutasem; Morris, Kyle; Watson, Peter J; Bottrill, Andrew R; Fairall, Louise; Smith, Corinne J; Schwabe, John WR

    2016-01-01

    The NuRD complex is a multi-protein transcriptional corepressor that couples histone deacetylase and ATP-dependent chromatin remodelling activities. The complex regulates the higher-order structure of chromatin, and has important roles in the regulation of gene expression, DNA damage repair and cell differentiation. HDACs 1 and 2 are recruited by the MTA1 corepressor to form the catalytic core of the complex. The histone chaperone protein RBBP4, has previously been shown to bind to the carboxy-terminal tail of MTA1. We show that MTA1 recruits a second copy of RBBP4. The crystal structure reveals an extensive interface between MTA1 and RBBP4. An EM structure, supported by SAXS and crosslinking, reveals the architecture of the dimeric HDAC1:MTA1:RBBP4 assembly which forms the core of the NuRD complex. We find evidence that in this complex RBBP4 mediates interaction with histone H3 tails, but not histone H4, suggesting a mechanism for recruitment of the NuRD complex to chromatin. DOI: http://dx.doi.org/10.7554/eLife.13941.001 PMID:27098840

  16. Theoretical studies on the interactions of XIAP-BIR3 domain with bicyclic and tricyclic core monovalent Smac mimetics.

    PubMed

    Ling, Baoping; Dong, Lihua; Zhang, Rui; Wang, Zhiguo; Liu, Yongjun; Liu, Chengbu

    2010-11-01

    X-linked IAP can bind caspase-9 and inhibit its activity. Mitochondrial protein Smac/DIABLO can also interact with XIAP and relieve the inhibition on caspase-9 to induce apoptosis. A series of artificial Smac mimetics have been used to mimic the Smac N-terminal tetrapeptide AVPI to bind to XIAP-BIR3, but these structural diverse mimetics exhibited distinct binding affinities. To get an insight into the binding nature and optimize the structures, molecular docking and dynamics simulations were used to study the binding of XIAP-BIR3 with three groups of Smac mimetics. The docking results reveal that these Smac mimetics anchored on the surface groove of XIAP-BIR3 and superimposed well with AVPI. The modifications on the seven-membered ring of bicyclic core segment do not strengthen the binding affinity, while a benzyl introduced to the five-membered ring is favorable to the binding. Molecular dynamics simulations on three typical systems show that these complexes are very stable. Hydrogen bonds between the bicyclic core segment and Thr308 play critical roles in maintaining the stability of complex. The binding free energies calculated by MM_PBSA method are consistent with the experimental results. PMID:20980180

  17. Out-of-core Interactive Display of Large Meshes Using an Oriented Bounding Box-based Hardware Depth Query

    SciTech Connect

    Ha, H; Gregorski, B; Joy, K I

    2004-06-24

    In this paper we present an occlusion culling method that uses hardware-based depth queries on oriented bounding boxes to cull unseen geometric primitives efficiently. An out-of-core design enables this method to interactively display data sets that are too large to fit into main memory. During a preprocessing phase, a spatial subdivision (such as an octree or BSP tree) of a given data set is constructed where, for each node, an oriented bounding box containing mesh primitives is computed using principal component analysis (PCA). At runtime, the tree indicated by the spatial subdivision is traversed in front-to-back order, and only nodes that are determined to be visible, based on a hardware accelerated depth query, are rendered.

  18. The interaction of core-collapse supernova ejecta with a companion star

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Wei; Tauris, T. M.; Röpke, F. K.; Moriya, T. J.; Kruckow, M.; Stancliffe, R. J.; Izzard, R. G.

    2015-12-01

    Context. The progenitors of many core-collapse supernovae (CCSNe) are expected to be in binary systems. After the SN explosion in a binary, the companion star may suffer from mass stripping and be shock heated as a result of the impact of the SN ejecta. If the binary system is disrupted by the SN explosion, the companion star is ejected as a runaway star, and in some cases as a hypervelocity star. Aims: By performing a series of three-dimensional (3D) hydrodynamical simulations of the collision of SN ejecta with the companion star, we investigate how CCSN explosions affect their binary companion. Methods: We use the BEC stellar evolution code to construct the detailed companion structure at the moment of SN explosion. The impact of the SN blast wave on the companion star is followed by means of 3D smoothed particle hydrodynamics (SPH) simulations using the Stellar GADGET code. Results: For main-sequence (MS) companion stars, we find that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta strongly increases with decreasing binary separation and increasing explosion energy. Their relationship can be approximately fitted by power laws, which is consistent with the results obtained from impact simulations of Type Ia SNe. However, we find that the impact velocity is sensitive to the momentum profile of the outer SN ejecta and, in fact, may decrease with increasing ejecta mass, depending on the modeling of the ejecta. Because most companion stars to Type Ib/c CCSNe are in their MS phase at the moment of the explosion, combined with the strongly decaying impact effects with increasing binary separation, we argue that the majority of these SNe lead to inefficient mass stripping and shock heating of the companion star following the impact of the ejecta. Conclusions: Our simulations show that the impact effects of Type Ib/c SN ejecta on the structure of MS companion

  19. Concrete-Water-Interaction and Ikaite (CaCO3.6H2O) Precipitation in a Man-Made River Bed

    NASA Astrophysics Data System (ADS)

    Boch, R.; Dietzel, M.; Reichl, P.; Leis, A.; Pölt, P.; Baldermann, A.

    2014-12-01

    Centimetre-thick, beige-colored and soft crusts were observed shortly after construction of a man-made river bed, i.e. a small natural river was bypassed flowing through a new bed lined with concrete and blocks. Hydrochemical investigations during wintertime - when water temperatures dropped down close to freezing - showed surprisingly high pH values up to 13.0 and elevated Ca2+ concentrations up to 200 mg/l. Both, the artifical and natural (downstream) section of the river bed were affected by the anomalous hydrochemistry and formation of prominent secondary precipitates. In order to better understand the particular and rapid water-rock-interaction, a hydrochemical monitoring program was launched and several of the delicate precipitates were recovered in refrigerator boxes in their original solution. The samples were analyzed in the laboratory within a few hours after sampling and stored at 1 °C. XRD and FT-IR patterns clearly revealed the predominant occurrence of "ikaite" in the crusts next to minor amounts of other carbonates (calcite, aragonite, vaterite) and detrital minerals. Ikaite - calcium carbonate hexahydrate - is a worldwide rarely documented carbonate mineral. This mineral is metastable and needs particular and narrow conditions in order to precipitate from solutions, i.e. a very limited water-temperature range between 0 and 4 °C (with ambient-pressure and low-salinity), highly alkaline pH conditions, high supersaturation values, and in many cases carbonate precipitation inhibitors (e.g. phosphates). Outside these conditions it disintegrates into calcite and water within minutes to hours. The few places of ikaite formation include Ikka Fjord in Greenland, Arctic- and Antarctic sea-ice and some sites of water mixing at Mono Lake, California. Combining detailed field monitoring results, solid-phase analyses and regional meteorological data (rainfall, water discharge, temperature) with hydrogeochemical modeling allows constraining the mechanisms of

  20. Magma interaction processes in syn-extensional granitoids: The Tertiary Menderes Metamorphic Core Complex, western Turkey

    NASA Astrophysics Data System (ADS)

    Erkül, Sibel Tatar; Erkül, Fuat

    2012-06-01

    Western Turkey, which forms the eastern part of the Aegean region, was subjected to continental extension that led to formation of metamorphic core complexes and associated syn-extensional granitoids. This study deals with petrogenesis of the syn-extensional Early Miocene Alaçamdağ (AG) and Middle Miocene Salihli (SG) granitoids and associated mafic microgranular enclaves (MME) in order to better understand the time-progressive evolution of the mantle sources beneath the extended continental crust in western Turkey. AG and SG granitoids consist of undeformed and ductility deformed granitoids together with abundant MMEs. They are calc-alkaline to high-K calc-alkaline rocks that are metaluminous to slightly peraluminous. Mg# of AG host rocks is slightly lower than that of SG host rocks. AG host rocks have higher Na2O, Ba, Rb, Rb/La and lower Al2O3, CaO, MgO, TiO2, Zr/Y values than those of the SG host rocks. AG and SG host rocks differ from those of MMEs, with their lower Al2O3, CaO, MgO, Fe2O3, TiO2, Sr, V, Mg# and higher SiO2 values. MMEs are intermediate, corresponding to monzonite, monzodiorite (in AG) and diorite (in SG) compositions and are more mafic with respect to their host rocks. In the primitive mantle (PM) normalized trace element patterns, host rock and MME samples have similar trace element patterns. All of these rocks are enriched in large ion lithophile elements (LILEs, Cs, Rb, Ba, Th, K and Sr) and strongly depleted high field strength elements (HFSEs, Ta, Nb, P, Ti) compared to the primitive mantle. The isotope ratios of the syn-extensional AG and SG rocks display increasing radiogenic strontium and decreasing radiogenic neodymium. Isotopic values for the AG and SG host rocks and MME samples are 87Sr/86Sr (AG host) = 0.708835-0.710206 and ɛNd(t) (AG host) = (- 5.36 to - 7.36); 87Sr/86Sr (AG MME) = 0.709107-0.709801 and ɛNd(t) (AG MME) = - 5.36 to - 7.36; 87Sr/86Sr (AG MME)=0.709107-0.709801 and ɛNd(t) (AG MME)=-5.55 to -6.51; 87Sr/86Sr (SG

  1. Interactive Organization of the Circadian Core Regulators PER2, BMAL1, CLOCK and PML

    PubMed Central

    Miki, Takao; Zhao, Zhaoyang; Lee, Cheng Chi

    2016-01-01

    The BMAL1 and CLOCK heterodimer in the mammalian circadian transcriptional complex is thought to be repressed by PER2 and CRY1 via direct interactions. We recently reported that PER2 is largely cytosolic in Pml−/− cells and did not co-immunoprecipitate (co-IP) with BMAL1 or CLOCK. Here, using multi-color immunofluorescence (IF) staining and co-IP, we observed a nuclear distribution of BMAL1 and a predominately cytosolic distribution of CLOCK in Pml−/− MEF. In the presence of WT PML, PER2 co-localized with BMAL1 in the nucleus. In Pml−/− MEF transfected with mutant K487R PML, we observed that BMAL1 and PER2 co-localized with K487R PML in the cytosol. Furthermore, cytosolic CLOCK and PER2 displayed a significant non-overlapping IF staining pattern. In Bmal1−/− MEF, CLOCK was primarily cytosolic while PML and PER2 were nuclear. Together, our studies suggest that PML mediates the binding of PER2 to BMAL1 in the BMAL1/CLOCK heterodimer and is an important component in the organization of a functional clock complex in the nucleus. Our studies also support that BMAL1 is important for CLOCK nuclear localization. PMID:27383066

  2. Interactive Organization of the Circadian Core Regulators PER2, BMAL1, CLOCK and PML.

    PubMed

    Miki, Takao; Zhao, Zhaoyang; Lee, Cheng Chi

    2016-01-01

    The BMAL1 and CLOCK heterodimer in the mammalian circadian transcriptional complex is thought to be repressed by PER2 and CRY1 via direct interactions. We recently reported that PER2 is largely cytosolic in Pml(-/-) cells and did not co-immunoprecipitate (co-IP) with BMAL1 or CLOCK. Here, using multi-color immunofluorescence (IF) staining and co-IP, we observed a nuclear distribution of BMAL1 and a predominately cytosolic distribution of CLOCK in Pml(-/-) MEF. In the presence of WT PML, PER2 co-localized with BMAL1 in the nucleus. In Pml(-/-) MEF transfected with mutant K487R PML, we observed that BMAL1 and PER2 co-localized with K487R PML in the cytosol. Furthermore, cytosolic CLOCK and PER2 displayed a significant non-overlapping IF staining pattern. In Bmal1(-/-) MEF, CLOCK was primarily cytosolic while PML and PER2 were nuclear. Together, our studies suggest that PML mediates the binding of PER2 to BMAL1 in the BMAL1/CLOCK heterodimer and is an important component in the organization of a functional clock complex in the nucleus. Our studies also support that BMAL1 is important for CLOCK nuclear localization. PMID:27383066

  3. Effect of dominant three-body interaction to the hard-core boson Hubbard model on a two-dimensional square lattice

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Guo, Huaiming

    2012-09-01

    The effect of dominant three-body interaction to the hard-core boson Hubbard model is studied on a two-dimensional square lattice. In terms of the quantum Monte Carlo method, a ρ = 2/3 solid phase is shown explicitly with the coexistence of a charge-density wave and a bond-order wave appearing due to the presence of the dominant three-body interaction. For the strong three-body interaction, the ρ = 2/3 solid phase appears between superfluid phases and shrinks as the strength of the three-body interaction decreases, forming a lobe structure in the phase diagram. For weak three-body interactions, the superfluid phase exists for the whole range of hard-core densities except the full filled case, where the system is a Mott insulator. Our results may be realized in cold-atom experiments.

  4. A new equation of state with light nuclei and their weak interactions in core-collapse supernova simulations

    SciTech Connect

    Furusawa, Shun; Yamada, Shoichi; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

    2014-05-02

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged-current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as ∼ 10% of those of nucleons around the bottom of the gain region. On the other hands, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light nuclei have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light nuclei, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  5. A new equation of state with light nuclei and their weak interactions in core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Furusawa, Shun; Nagakura, Hiroki; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

    2014-05-01

    We perform numerical experiments to investigate the influence of inelastic neutrino reactions with light nuclei on the standing accretion shock instability. The time evolutions of shock waves are calculated with a simple light-bulb approximation for the neutrino transport and a multi-nuclei equation of state. The neutrino absorptions and inelastic interactions with deuterons, tritons, helions and alpha particles are taken into account in the hydrodynamical simulations in addition to the ordinary charged-current interactions with nucleons. Axial symmetry is assumed but no equatorial symmetry is imposed. We show that the heating rates of deuterons reach as high as ˜ 10% of those of nucleons around the bottom of the gain region. On the other hands, alpha particles heat the matter near the shock wave, which is important when the shock wave expands and density and temperature of matter become low. It is also found that the models with heating by light nuclei have different evolutions from those without it in non-linear evolution phase. The matter in the gain region has various densities and temperatures and there appear regions that are locally rich in deuterons and alpha particles. These results indicate that the inelastic reactions of light nuclei, especially deuterons, should be incorporated in the simulations of core-collapse supernovae.

  6. Lunar concrete for construction

    SciTech Connect

    Cullingford, H.S.; Keller, M.D.

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base. 10 refs., 3 figs., 2 tabs.

  7. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

  8. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1992-01-01

    Feasibility of using concrete for lunar base construction was discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the Moon are provided in this paper, along with specific conclusions from the existing database.

  9. Aptamers to Escherichia coli core RNA polymerase that sense its interaction with rifampicin, sigma-subunit and GreB.

    PubMed

    Kulbachinskiy, Andrey; Feklistov, Andrey; Krasheninnikov, Igor; Goldfarb, Alex; Nikiforov, Vadim

    2004-12-01

    Bacterial RNA polymerase (RNAP) is the central enzyme of gene expression that is responsible for the synthesis of all types of cellular RNAs. The process of transcription is accompanied by complex structural rearrangements of RNAP. Despite the recent progress in structural studies of RNAP, detailed mechanisms of conformational changes of RNAP that occur at different stages of transcription remain unknown. The goal of this work was to obtain novel ligands to RNAP which would target different epitopes of the enzyme and serve as specific probes to study the mechanism of transcription and conformational flexibility of RNAP. Using in vitro selection methods, we obtained 13 classes of ssDNA aptamers against Escherichia coli core RNAP. The minimal nucleic acid scaffold (an oligonucleotide construct imitating DNA and RNA in elongation complex), rifampicin and the sigma70-subunit inhibited binding of the aptamers to RNAP core but did not affect the dissociation rate of preformed RNAP-aptamer complexes. We argue that these ligands sterically block access of the aptamers to their binding sites within the main RNAP channel. In contrast, transcript cleavage factor GreB increased the rate of dissociation of preformed RNAP-aptamer complexes. This suggested that GreB that binds RNAP outside the main channel actively disrupts RNAP-aptamer complexes by inducing conformational changes in the channel. We propose that the aptamers obtained in this work will be useful for studying the interactions of RNAP with various ligands and regulatory factors and for investigating the conformational flexibility of the enzyme. PMID:15606780

  10. Development of ultrasonic methods for the nondestructive inspection of concrete

    NASA Astrophysics Data System (ADS)

    Claytor, T. M.; Ellingson, W. A.

    1983-08-01

    Nondestructive inspection of Portland cement and refractory concrete is conducted to determine strength, thickness, presence of voids or foreign matter, presence of cracks, amount of degradation due to chemical attack, and other properties without the necessity of coring the structure (which is usually accomplished by destructively removing a sample). The state of the art of acoustic nondestructive testing methods for Portland cement and refractory concrete is reviewed. Most nondestructive work on concrete has concentrated on measuring acoustic velocity by through transmission methods. Development of a reliable pitch-catch or pulse-echo system would provide a method of measuring thickness with access from only one side of the concrete.

  11. Development of ultrasonic methods for the nondestructive inspection of concrete

    SciTech Connect

    Claytor, T.N.; Ellingson, W.A.

    1983-08-01

    Nondestructive inspection of Portland cement and refractory concrete is conducted to determine strength, thickness, presence of voids or foreign matter, presence of cracks, amount of degradation due to chemical attack, and other properties without the necessity of coring the structure (which is usually accomplished by destructively removing a sample). This paper reviews the state of the art of acoustic nondestructive testing methods for Portland cement and refractory concrete. Most nondestructive work on concrete has concentrated on measuring acoustic velocity by through transmission methods. Development of a reliable pitch-catch or pulse-echo system would provide a method of measuring thickness with access from only one side of the concrete.

  12. Effects of the interactions of classical swine fever virus core protein with proteins of SUMOylation pathway on virulence in swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The classical swine fever virus (CSFV) nucleocapsid or Core protein serves a protective function for the viral RNA, and acts as a transcriptional regulator. However studies involving the CSFV Core protein have been limited. To gain insight into other functions of the Core protein, particularly into ...

  13. An investigation of tendon sheathing filler migration into concrete

    SciTech Connect

    Naus, D.J.; Oland, C.B.

    1998-03-01

    During some of the inspections at nuclear power plants with prestressed concrete containments, it was observed that the containments has experienced leakage of the tendon sheathing filler (i.e., streaks). The objective of this activity was to provide an indication of the extent of tendon sheathing filler leakage into the concrete and its affects on concrete properties. Literature was reviewed and concrete core samples were obtained from the Trojan Nuclear Plant and tested. The literature primarily addressed effects of crude or lubricating oils that are known to cause concrete damage. However, these materials have significantly different characteristics relative to the materials used as tendon sheathing fillers. Examination and testing of the concrete cores indicated that the appearance of tendon sheathing filler on the concrete surface was due to leakage from the conduits and its subsequent migration through cracks that were present. Migration of the tendon sheathing filler was confined to the cracks and there was no perceptible movement into the concrete. Results of compressive strength testing indicated that the concrete quality was consistent in the containment and that the strength had increased over 40% in 25.4 years relative to the average compressive strength at 28-days age.

  14. Porosity, pore size distribution and in situ strength of concrete

    SciTech Connect

    Kumar, Rakesh; Bhattacharjee, B

    2003-01-01

    In this study, in situ strength of concrete was determined through compression test of cores drilled out from laboratory cast beams. The apparent porosity and pore size distribution of the same concrete were determined through mercury intrusion porosimetry, performed on small-drilled cores. The normal-strength concrete mixes used in the experimental investigation were designed to exhibit a wide variation in their strengths. To ensure further variation in porosity, pore size distribution and strength, two modes of compaction, two varieties of coarse aggregates, different levels of age, curing period and exposure condition of concrete were also introduced in experimental scheme. With the data so generated, an appraisal of the most frequently referred relationships involving strength, porosity and pore size of cement-based materials was carried out. Finally, a new empirical model relating the in situ strength of concrete with porosity, pore size characteristics, cement content, aggregate type, exposure conditions, etc., is presented.

  15. Emotional Intolerance and Core Features of Anorexia Nervosa: A Dynamic Interaction during Inpatient Treatment? Results from a Longitudinal Diary Study

    PubMed Central

    Stroe-Kunold, Esther; Friederich, Hans-Christoph; Stadnitski, Tatjana; Wesche, Daniela; Herzog, Wolfgang; Schwab, Michael; Wild, Beate

    2016-01-01

    Objective The role of emotion dysregulation with regard to the psychopathology of anorexia nervosa (AN) is increasingly discussed. It is both assumed that AN symptoms have an impact on difficulties in tolerating aversive emotions and that—conversely—emotion dysregulation influences AN. To date, such conclusions are drawn on the basis of cross-sectional data not allowing for inferences on the temporal dynamics. The current study investigates the longitudinal interaction between emotional intolerance and core AN symptoms over the course of inpatient treatment by comparing patients with high (BMI<15 kg/m2) vs. low symptom severity (HSS vs. LSS). Method The study adopted a longitudinal, process-oriented design with N = 16 analysed electronic diaries. Throughout the course of their inpatient treatment, the patients answered questions daily about emotional intolerance and their AN-specific cognitions and behaviours. The temporal dynamics between emotional intolerance and these variables were analysed using a multivariate time series approach. Results The time series of the processes under investigation adequately reflected the individual treatment courses. The majority of significant linear time trends was found for HSS patients. Most importantly, analysis revealed significant temporal interactions between emotional intolerance and AN symptoms in almost 70% of HSS patients. Thereby, up to 37% of variance in eating restraint and up to 23% in weight concern could be attributed to changes in emotional intolerance. Conclusions The findings support the notion that intolerable unpleasant emotions in severely affected AN patients influence their psychopathology. Additionally, time series analysis outlined the inter-individual heterogeneity of psychosomatic treatment courses of AN patients. PMID:27191959

  16. Effect of polar intermolecular interactions on the elastic constants of bent-core nematics and the origin of the twist-bend phase.

    PubMed

    Osipov, M A; Pajak, G

    2016-04-01

    A molecular theory of both elastic constants and the flexoelectric coefficients of bent-core nematic liquid crystals has been developed taking into account dipole-dipole interactions as well as polar interactions determined by the bent molecular shape. It has been shown that if polar interactions are neglected, the elastic constants are increasing monotonically with the decreasing temperature. On the other hand, dipolar interactions between bent-core molecules may result in a dramatic increase of the bend flexocoefficient. As a result, the flexoelectric contribution to the bend elastic constant increases significantly, and the bend elastic constant appears to be very small throughout the nematic range and may vanish at a certain temperature. This temperature may then be identified as a temperature of the elastic instability of the bent-core nematic phase which induces a transition into the modulated phases with bend deformations like recently reported twist-bend phase. The temperature variation of the elastic constants is qualitatively similar to the typical experimental data for bent-core nematics. PMID:27118535

  17. Extended-soft-core baryon-baryon model. I. Nucleon-nucleon scattering with the ESC04 interaction

    SciTech Connect

    Rijken, Th.A.

    2006-04-15

    The NN results are presented from the extended-soft-core (ESC) interactions. They consist of local and nonlocal potentials due to (i) one-boson-exchanges (OBE), which are the members of nonets of pseudoscalar, vector, scalar, and axial mesons (ii) diffractive exchanges (iii) two-pseudoscalar exchanges (PS-PS), and (iv) meson-pair exchanges (MPE). We describe a fit to the pp and np data for 0{<=}T{sub lab}{<=}350 MeV, having a typical {chi}{sup 2}/N{sub data}=1.155. Here, we used {approx}20 quasi-free physical parameters, which are coupling constants and cutoff masses. A remarkable feature of the couplings is that we were able to require them to follow rather closely the pattern predicted by the {sup 3}P{sub 0} quark-pair-creation (QPC) model. As a result the 11 OBE couplings are rather constrained, i.e., quasi free. Also, the deuteron binding energy and the several NN scattering lengths are fitted.

  18. Interactions of core-shell quantum dots with metal resistant bacterium Cupriavidus metallidurans: consequences for Cu and Pb removal.

    PubMed

    Slaveykova, Vera I; Pinheiro, José Paulo; Floriani, Magali; Garcia, Miguel

    2013-10-15

    In the present study we address the interactions of carboxyl-CdSe/ZnS core/shell quantum dots (QDs), as a model of water dispersible engineered nanoparticles, and metal resistant bacteria Cupriavidus metallidurans, largely used in metal decontamination. The results demonstrate that QDs with average hydrodynamic size of 12.9 nm adhere to C. metallidurans. The percentage of bacterial cells displaying QD-fluorescence increased proportionally with contact time and QD concentration in bacterial medium demonstrating the association of QDs with the metal resistant bacteria. No evidence of QD internalization into bacterial cytoplasm was found by transmission electron microscopy with energy dispersive X-ray spectrometry, however QD clusters of sizes between 20 and 50 nm were observed on the bacterial surface and in the bacterial periplasmic compartment; observations consistent with the losses of membrane integrity induced by QDs. The presence of 20 nM QDs induced about 2-fold increase in Cu and Pb uptake fluxes by C. metallidurans exposed to 500 nM Pb or Cu, respectively. Overall, the results of this work suggest that when present in mixture with Cu and Pb, low levels of QDs originating from possible incidental release or QD disposal could increase metal accumulation in metal resistant bacterium. PMID:23912077

  19. ZFHX4 interacts with the NuRD core member CHD4 and regulates the glioblastoma tumor initiating cell state

    PubMed Central

    Chudnovsky, Yakov; Kim, Dohoon; Zheng, Siyuan; Whyte, Warren A.; Bansal, Mukesh; Bray, Mark-Anthony; Gopal, Shuba; Theisen, Matthew A.; Bilodeau, Steve; Thiru, Prathapan; Muffat, Julien; Yilmaz, Omer H.; Mitalipova, Maya; Woolard, Kevin; Lee, Jeongwu; Nishimura, Riko; Sakata, Nobuo; Fine, Howard A.; Carpenter, Anne E.; Silver, Serena J.; Verhaak, Roel G. W.; Califano, Andrea; Young, Richard A.; Ligon, Keith L.; Mellinghoff, Ingo K.; Root, David E.; Sabatini, David M.; Hahn, William C.; Chheda, Milan G.

    2014-01-01

    Summary Glioblastomas (GBM) harbor subpopulations of therapy-resistant tumor initiating cells (TICs) that are self-renewing and multipotent. To understand the regulation of the TIC state, we performed an image-based screen for genes regulating GBM TIC maintenance and identified ZFHX4, a 397-kDa transcription factor. ZFHX4 is required to maintain TIC-associated and normal human neural precursor cell phenotypes in vitro, suggesting that ZFHX4 regulates differentiation, and its suppression increases glioma-free survival in intracranial xenografts. ZFHX4 interacts with CHD4, a core member of the NuRD (nucleosome remodeling and deacetylase) complex. ZFHX4 and CHD4 bind to overlapping sets of genomic loci and control similar gene expression programs. Using expression data derived from GBM patients, we found that ZFHX4 significantly affects CHD4-mediated gene expression perturbations, which defines ZFHX4 as a master regulator of CHD4. These observations define ZFHX4 as a regulatory factor that links the chromatin remodeling NuRD complex and the GBM TIC state. PMID:24440720

  20. Data assimilative modeling investigation of Gulf Stream Warm Core Ring interaction with continental shelf and slope circulation

    NASA Astrophysics Data System (ADS)

    Chen, Ke; He, Ruoying; Powell, Brian S.; Gawarkiewicz, Glen G.; Moore, Andrew M.; Arango, Hernan G.

    2014-09-01

    A data assimilative ocean circulation model is used to hindcast the interaction between a large Gulf Stream Warm Core Ring (WCR) with the Mid-Atlantic Bight (MAB) shelf and slope circulation. Using the recently developed Incremental Strong constraint 4D Variational (I4D-Var) data assimilation algorithm, the model assimilates mapped satellite sea surface height (SSH), sea surface temperature (SST), in situ temperature, and salinity profiles measured by expendable bathythermograph, Argo floats, shipboard CTD casts, and glider transects. Model validations against independent hydrographic data show 60% and 57% error reductions in temperature and salinity, respectively. The WCR significantly changed MAB continental slope and shelf circulation. The mean cross-shelf transport induced by the WCR is estimated to be 0.28 Sv offshore, balancing the mean along-shelf transport by the shelfbreak jet. Large heat/salt fluxes with peak values of 8900 W m-2/4 × 10-4 kg m-2 s-1 are found when the WCR was impinging upon the shelfbreak. Vorticity analysis reveals the nonlinear advection term, as well as the residual of joint effect of baroclinicity and bottom relief (JEBAR) and advection of potential vorticity (APV) play important roles in controlling the variability of the eddy vorticity.

  1. Surface treated polypropylene (PP) fibres for reinforced concrete

    SciTech Connect

    López-Buendía, Angel M.; Romero-Sánchez, María Dolores; Climent, Verónica

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  2. Lunar concrete: Prospects and challenges

    NASA Astrophysics Data System (ADS)

    Khitab, Anwar; Anwar, Waqas; Mehmood, Imran; Kazmi, Syed Minhaj Saleem; Munir, Muhammad Junaid

    2016-02-01

    The possibility of using concrete as a construction material at the Moon surface is considered. Dissimilarities between the Earth and the Moon and their possible effects on concrete are also emphasized. Availability of constituent materials for concrete at lunar surface is addressed. An emphasis is given to two types of materials, namely, hydraulic concrete and sulfur concrete. Hydraulic concrete necessitates the use of water and sulfur concrete makes use of molten sulfur in lieu of cement and water.

  3. Nondestructive evaluation of thick concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight A.

    2015-03-01

    Concrete has been used in the construction of nuclear power plants (NPPs) due to three primary properties: its low cost, structural strength, and ability to shield radiation. Examples of concrete structures important to the safety of Light Water Reactor (LWR) plants include the containment building, spent fuel pool, and cooling towers. Use in these structures has made concrete's long-term performance crucial for the safe operation of commercial NPPs. Extending LWR operating period to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. New mechanisms of materials degradation are also possible. This creates the need to be able to nondestructively evaluate the current subsurface concrete condition of aging concrete material in NPP structures. The size and complexity of NPP containment structures and heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular nondestructive evaluation (NDE) technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Representative large heavily reinforced concrete specimens would allow for comparative testing to evaluate the state-of-the-art NDE in this area and to identify additional developments necessary to address the challenges potentially found in NPPs.

  4. The role of magnetic interactions in exchange bias properties of MnFe2O4@γ-Fe2O3 core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Silva, F. G.; Aquino, R.; Tourinho, F. A.; Stepanov, V. I.; Raikher, Yu L.; Perzynski, R.; Depeyrot, J.

    2013-07-01

    Low-temperature magnetic properties of assemblies of 3.3 nm sized nanoparticles (NPs) based on a MnFe2O4 core protected by a maghemite shell are investigated. These NPs are obtained by a chemical core/shell method developed for the synthesis of the electrostatically stabilized ferrofluid colloidal dispersions that we probe here. They are model systems where the interparticle interaction is tuned by the NP volume fractions, ranging here between 0.4% and 13.9%. It has been shown that these NPs consist of a well-ordered ferrimagnetic core surrounded by a disordered spin glass-like surface layer and that they display uniaxial magnetic anisotropy. We compare the magnetic hysteresis loops of non-textured frozen dispersions (with magnetic anisotropy axis of NPs distributed at random) with those of a powder based on the same NPs. After cooling under field the hysteresis loops shift along the H axis, expressing the coupling between the spin-ordered cores and the disordered surface layers. The negative H-shift provides an evaluation for the exchange bias (EB) field. The EB field is optimum for a cooling field of the order of the anisotropy field. A comparison between frozen dispersions and disordered powder allows us to distinguish the influence of intra- and interparticle interactions on the EB. Interparticle collective effects dominate in the powder while an intraparticle EB, eventually hindered by dipolar interactions at large volume fraction, is observed in frozen dispersions.

  5. Applications for concrete offshore

    SciTech Connect

    Not Available

    1982-01-01

    The report collects and summarizes the various proposals for development offshore which have in common the use of concrete as the main structural material, and where possible, indicates their relative feasibility. A study encompassing such diverse schemes as offshore windmills, concrete LNG carriers, hydrocarbon production platforms and floating airports cannot be completely exhaustive on each subject, so references to sources of further information have been given wherever possible. Details of individual projects and proposals are included for Power plants, Hydrocarbon production platforms, Concrete ships, Storage systems and industrial plants, Subsea systems, Offshore islands, Coastal works and Other concrete structures.

  6. Radionuclide Retention in Concrete Wasteforms

    SciTech Connect

    Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

    2011-09-30

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

  7. Properties of salt-saturated concrete and grout after six years in situ at the Waste Isolation Pilot Plant

    SciTech Connect

    Wakeley, L.D.; Harrington, P.T.; Weiss, C.A. Jr.

    1993-06-01

    Samples of concrete and grout were recovered from short boreholes in the repository floor at the Waste Isolation Pilot Plant more than six years after the concrete and grout were placed. Plugs from the Plug Test Matrix of the Plugging and Sealing Program of Sandia National Laboratories were overcored to include a shell of host rock. The cores were analyzed at the Waterways Experiment Station to assess their condition after six years of service, having potentially been exposed to those aspects of their service environment (salt, brine, fracturing, anhydrite, etc.) that could cause deterioration. Measured values of compressive strength and pulse velocity of both the grout and the concrete equaled or exceeded values from tests performed on laboratory-tested samples of the same mixtures at ages of one month to one year after casting. The phase assemblages had changed very little. Materials performed as intended and showed virtually no chemical or physical evidence of deterioration. The lowest values for strength and pulse velocity were measured for samples taken from the Disturbed Rock Zone, indicating the influence of cracking in this zone on the properties of enclosed seal materials. There was evidence of movement of brine in the system. Crystalline phases containing magnesium, potassium, sulfate, and other ions had been deposited on free surfaces in fractures and pilot holes. There was a reaction rim in the anhydrite immediately surrounding each recovered borehole plug, suggesting interaction between grout or concrete and host rock. However, the chemical changes apparent in this reaction rim were not reflected in the chemical composition of the adjacent concrete or grout. The grout and concrete studied here showed no signs of the deterioration found to have occurred in some parts of the concrete liner of the Waste Isolation Pilot Plant waste handling shaft.

  8. Identification and targeting of an interaction between a tyrosine motif within hepatitis C virus core protein and AP2M1 essential for viral assembly.

    PubMed

    Neveu, Gregory; Barouch-Bentov, Rina; Ziv-Av, Amotz; Gerber, Doron; Jacob, Yves; Einav, Shirit

    2012-01-01

    Novel therapies are urgently needed against hepatitis C virus infection (HCV), a major global health problem. The current model of infectious virus production suggests that HCV virions are assembled on or near the surface of lipid droplets, acquire their envelope at the ER, and egress through the secretory pathway. The mechanisms of HCV assembly and particularly the role of viral-host protein-protein interactions in mediating this process are, however, poorly understood. We identified a conserved heretofore unrecognized YXXΦ motif (Φ is a bulky hydrophobic residue) within the core protein. This motif is homologous to sorting signals within host cargo proteins known to mediate binding of AP2M1, the μ subunit of clathrin adaptor protein complex 2 (AP-2), and intracellular trafficking. Using microfluidics affinity analysis, protein-fragment complementation assays, and co-immunoprecipitations in infected cells, we show that this motif mediates core binding to AP2M1. YXXΦ mutations, silencing AP2M1 expression or overexpressing a dominant negative AP2M1 mutant had no effect on HCV RNA replication, however, they dramatically inhibited intra- and extracellular infectivity, consistent with a defect in viral assembly. Quantitative confocal immunofluorescence analysis revealed that core's YXXΦ motif mediates recruitment of AP2M1 to lipid droplets and that the observed defect in HCV assembly following disruption of core-AP2M1 binding correlates with accumulation of core on lipid droplets, reduced core colocalization with E2 and reduced core localization to trans-Golgi network (TGN), the presumed site of viral particles maturation. Furthermore, AAK1 and GAK, serine/threonine kinases known to stimulate binding of AP2M1 to host cargo proteins, regulate core-AP2M1 binding and are essential for HCV assembly. Last, approved anti-cancer drugs that inhibit AAK1 or GAK not only disrupt core-AP2M1 binding, but also significantly inhibit HCV assembly and infectious virus production

  9. ALMA OBSERVATIONS OF A HIGH-DENSITY CORE IN TAURUS: DYNAMICAL GAS INTERACTION AT THE POSSIBLE SITE OF A MULTIPLE STAR FORMATION

    SciTech Connect

    Tokuda, Kazuki; Onishi, Toshikazu; Saigo, Kazuya; Kawamura, Akiko; Fukui, Yasuo; Inutsuka, Shu-ichiro; Tachihara, Kengo; Matsumoto, Tomoaki; Machida, Masahiro N.; Tomida, Kengo

    2014-07-01

    Starless dense cores eventually collapse dynamically, forming protostars inside them, and the physical properties of the cores determine the nature of the forming protostars. We report ALMA observations of dust continuum emission and molecular rotational lines toward MC27 or L1521F, which is considered to be very close to the first protostellar core phase. We found a few starless high-density cores, one of which has a very high density of ∼10{sup 7} cm{sup –3}, within a region of several hundred AU around a very low-luminosity protostar detected by Spitzer. A very compact bipolar outflow with a dynamical timescale of a few hundred years was found toward the protostar. The molecular line observation shows several cores with an arc-like structure, possibly due to the dynamical gas interaction. These complex structures revealed in the present observations suggest that the initial condition of star formation is highly dynamical in nature, which is considered to be a key factor in understanding fundamental issues of star formation such as the formation of multiple stars and the origin of the initial mass function of stars.

  10. DFT study of Fe-Ni core-shell nanoparticles: Stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth

    NASA Astrophysics Data System (ADS)

    Yang, Zhimin; Wang, Qiang; Shan, Xiaoye; Li, Wei-qi; Chen, Guang-hui; Zhu, Hongjun

    2015-02-01

    Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.

  11. DFT study of Fe-Ni core-shell nanoparticles: Stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth

    SciTech Connect

    Yang, Zhimin; Wang, Qiang Shan, Xiaoye; Zhu, Hongjun; Li, Wei-qi; Chen, Guang-hui

    2015-02-21

    Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.

  12. Durability of high performance concrete in magnesium brine

    SciTech Connect

    Tumidajski, P.J.; Chan, G.W.

    1996-04-01

    The durability of six concretes exposed to magnesium brine was monitored for 24 months. These concretes incorporated ground granulated blast furnace slag, silica fume, and fly ash. The Young`s moduli, chloride penetrations, and median pore diameters were measured. There was a cyclic nature to these properties due to the complicated interaction of hydration with magnesium, chloride and sulfate attack. Mineral admixtures, in combination with a long initial cure, provided the most durable concrete. Concrete with 65% slag had the best overall durability to the brines tested.

  13. Prestressed concrete for the storage of liquefied gases

    SciTech Connect

    Bruggeling, A.S.G.

    1981-01-01

    Both concrete and prestressing-steel materials retain their strengths at cryogenic temperatures, making them ideal for LNG storage tanks and similar structures. Prestressed concrete lends itself to a wide variety of configurations, from containment dikes to integrated tank systems in which the steel, insulation, and concrete must interact efficiently. Of major importance in building prestressed-concrete storage tanks are the design loads and load factors to be adopted, especially the so-called special loads that depend on the nature and quantity of the product to be stored, the type of installation involved, the siting of the storage facilities, and the tank construction (flexible or rigid).

  14. Methods for ultimate load analysis of concrete containments

    SciTech Connect

    Dunham, R.S.; Rashid, Y.R.; Yuan, K.A.; Lu, Y.M.

    1985-06-01

    The objective of the research project described in this interim report is to develop a qualified methodology for the ultimate load analysis of concrete containment structures. The EPRI-sponsored nonlinear finite element code ABAQUS-EPGEN, which has recently been modified to incorporate a constitutive model for plain concrete and modeling capabilities for reinforced and prestressed concrete containments, is utilized as the structural analysis tool in this development. The ABAQUS-EPGEN concrete modeling and analysis capabilities are first evaluated by comparing measured data with code predictions for full-scale reinforced concrete slab specimens tested under uniaxial and biaxial tension. These specimen tests simulate the behavior of the cylindrical wall of a typical concrete containment structure under internal pressure. The calculated and measured strain comparisons are used to improve the constitutive model and to qualify the code for concrete containment analysis. The second part of this effort deals with the ultimate load analysis of reinforced and prestressed containments to determine bounds on the global overpressure capacities of typical concrete containment structures. The third part of this effort further examines such local effects through a substructural analysis of the liner-concrete interaction at major concrete cracks.

  15. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  16. Seismic retrofitting of reinforced concrete frame structures using GFRP-tube-confined-concrete composite braces

    NASA Astrophysics Data System (ADS)

    Moghaddasi B., Nasim S.; Zhang, Yunfeng; Hu, Xiaobin

    2012-03-01

    This paper presents a new type of structural bracing intended for seismic retrofitting use in framed structures. This special composite brace, termed glass-fiber-reinforced-polymer (GFRP)-tube-confined-concrete composite brace, is comprised of concrete confined by a GFRP tube and an inner steel core for energy dissipation. Together with a contribution from the GFRP-tube confined concrete, the composite brace shows a substantially increased stiffness to control story drift, which is often a preferred feature in seismic retrofitting. An analysis model is established and implemented in a general finite element analysis program — OpenSees, for simulating the load-displacement behavior of the composite brace. Using this model, a parametric study of the hysteretic behavior (energy dissipation, stiffness, ductility and strength) of the composite brace was conducted under static cyclic loading and it was found that the area ratio of steel core to concrete has the greatest influence among all the parameters considered. To demonstrate the application of the composite brace in seismic retrofitting, a three-story nonductile reinforced concrete (RC) frame structure was retrofitted with the composite braces. Pushover analysis and nonlinear time-history analyses of the retrofitted RC frame structure was performed by employing a suite of 20 strong ground motion earthquake records. The analysis results show that the composite braces can effectively reduce the peak seismic responses of the RC frame structure without significantly increasing the base shear demand.

  17. Concrete sample point: 304 Concretion Facility

    SciTech Connect

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  18. Retrieval of concrete words involves more contextual information than abstract words: multiple components for the concreteness effect.

    PubMed

    Xiao, Xin; Zhao, Di; Zhang, Qin; Guo, Chun-yan

    2012-03-01

    The current study used the directed forgetting paradigm in implicit and explicit memory to investigate the concreteness effect. Event-related potentials (ERPs) were recorded to explore the neural basis of this phenomenon. The behavioral results showed a clear concreteness effect in both implicit and explicit memory tests; participants responded significantly faster to concrete words than to abstract words. The ERP results revealed a concreteness effect (N400) in both the encoding and retrieval phases. In addition, behavioral and ERP results showed an interaction between word concreteness and memory instruction (to-be-forgotten vs. to-be-remembered) in the late epoch of the explicit retrieval phase, revealing a significant concreteness effect only under the to-be-remembered instruction condition. This concreteness effect was realized as an increased P600-like component in response to concrete words relative to abstract words, likely reflecting retrieval of contextual details. The time course of the concreteness effect suggests advantages of concrete words over abstract words due to greater contextual information. PMID:22041121

  19. Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

    NASA Astrophysics Data System (ADS)

    Zhao, Yi.; Xu, Li. Hua.

    2016-06-01

    This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

  20. Performance of Waterless Concrete

    NASA Technical Reports Server (NTRS)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  1. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as the their capability to prevent or inhibit the attachment of marine fouling organisms to concrete. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6 1/2 years in seawater.

  2. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as to their capability to prevent or inhibit the attachment of marine fouling organisms to concrete for OTEC plants. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6-1/2 years in seawater.

  3. Effect of insulating concrete forms in concrete compresive strength

    NASA Astrophysics Data System (ADS)

    Martinez Jerez, Silvio R.

    The subject presented in this thesis is the effect of Insulating Concrete Forms (ICF's) on concrete compressive strength. This work seeks to identify if concrete cured in ICF's has an effect in compressive strength due to the thermal insulation provided by the forms. Modern construction is moving to energy efficient buildings and ICF's is becoming more popular in new developments. The thesis used a concrete mixture and a mortar mixture to investigate the effects of ICF's on concrete compressive strength. After the experimentations were performed, it was concluded that the ICF's do affect concrete strength. It was found that the forms increase concrete strength without the need for additional curing water. An increase of 50% in strength at 56 days was obtained. It was concluded that the longer concrete cures inside ICF's, the higher strength it reaches, and that ICF's effect on concrete strength is proportional to volume of concrete.

  4. Differential Effects of Accumbens Core vs. Shell Lesions in a Rat Concurrent Conditioned Place Preference Paradigm for Cocaine vs. Social Interaction

    PubMed Central

    Fritz, Michael; Rawas, Rana El; Klement, Sabine; Kummer, Kai; Mayr, Michael J.; Eggart, Vincent; Salti, Ahmad; Bardo, Michael T.; Saria, Alois; Zernig, Gerald

    2011-01-01

    Background A main challenge in the therapy of drug dependent individuals is to help them reactivate interest in non-drug-associated activities. Among these activities, social interaction is doubly important because treatment adherence itself depends on it. We previously developed a rat experimental model based on the conditioned place preference (CPP) paradigm in which only four 15-min episodes of social interaction with a gender- and weight-matched male conspecific (i) reversed CPP from cocaine to social interaction despite continuing cocaine training and (ii) prevented the reinstatement of cocaine CPP. In the present study, we investigated if the two subregions of the nucleus accumbens (Acb), i.e., the core (AcbC) and the shell (AcbSh), would differentially affect CPP for cocaine vs social interaction. Methodology/Principal Findings Animals were concurrently trained for CPP pairing cocaine with one compartment and social interaction with the other (i.e., mutually exclusive stimulus presentation during training). Excitotoxic lesioning of the AcbC or the BLA shifted CPP toward social interaction, whereas AcbSh inactivation shifted CPP toward cocaine. Conclusions Overall, our findings suggest that inactivation of the AcbC or the BLA is sufficient to shift CPP away from a drug of abuse toward social interaction. Lesioning the AcbSh produced the opposite effect. PMID:22046347

  5. Electrokenitic Corrosion Treatment of Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E (Inventor)

    2015-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  6. An advanced coarse-grained nucleosome core particle model for computer simulations of nucleosome-nucleosome interactions under varying ionic conditions.

    PubMed

    Fan, Yanping; Korolev, Nikolay; Lyubartsev, Alexander P; Nordenskiöld, Lars

    2013-01-01

    In the eukaryotic cell nucleus, DNA exists as chromatin, a compact but dynamic complex with histone proteins. The first level of DNA organization is the linear array of nucleosome core particles (NCPs). The NCP is a well-defined complex of 147 bp DNA with an octamer of histones. Interactions between NCPs are of paramount importance for higher levels of chromatin compaction. The polyelectrolyte nature of the NCP implies that nucleosome-nucleosome interactions must exhibit a great influence from both the ionic environment as well as the positively charged and highly flexible N-terminal histone tails, protruding out from the NCP. The large size of the system precludes a modelling analysis of chromatin at an all-atom level and calls for coarse-grained approximations. Here, a model of the NCP that include the globular histone core and the flexible histone tails described by one particle per each amino acid and taking into account their net charge is proposed. DNA wrapped around the histone core was approximated at the level of two base pairs represented by one bead (bases and sugar) plus four beads of charged phosphate groups. Computer simulations, using a Langevin thermostat, in a dielectric continuum with explicit monovalent (K(+)), divalent (Mg(2+)) or trivalent (Co(NH(3))(6) (3+)) cations were performed for systems with one or ten NCPs. Increase of the counterion charge results in a switch from repulsive NCP-NCP interaction in the presence of K(+), to partial aggregation with Mg(2+) and to strong mutual attraction of all 10 NCPs in the presence of CoHex(3+). The new model reproduced experimental results and the structure of the NCP-NCP contacts is in agreement with available data. Cation screening, ion-ion correlations and tail bridging contribute to the NCP-NCP attraction and the new NCP model accounts for these interactions. PMID:23418426

  7. ALMA Observations of a High-density Core in Taurus: Dynamical Gas Interaction at the Possible Site of a Multiple Star Formation

    NASA Astrophysics Data System (ADS)

    Tokuda, Kazuki; Onishi, Toshikazu; Saigo, Kazuya; Kawamura, Akiko; Fukui, Yasuo; Matsumoto, Tomoaki; Inutsuka, Shu-ichiro; Machida, Masahiro N.; Tomida, Kengo; Tachihara, Kengo

    2015-08-01

    It is crucially important to observe dense cores in order to investigate the initial condition of star formation since protostars are formed via dynamical collapse of dense cores, inhering the physical properties from their natal dense cores. Here we present the results of ALMA Cycle 0 and Cycle 1 observations of dust continuum emission and molecular rotational lines toward a dense core, MC27 (aka L1521F), which is considered to be very close to the first protostellar core phase.The Cycle 0 observations revealed complex structures at the center. We found a few starless high-density cores, one of which (MMS2) has a very high density of ~107 cm-3, around the very low-luminousity protostar detected by Spitzer. A very compact bipolar outflow with a dynamical timescale of a few hundred years was found toward the protostar. The HCO+ (3-2) observation shows several cores associated with an arc-like structure whose length is ~2000 AU, possibly due to the dynamical gas interaction. These complex structures suggest that the initial condition of star formation is highly dynamical in nature, which is considered to be a key factor in understanding fundamental issues of star formation such as origins of the stellar multiplicity and the initial mass function. These initial Cycle 0 results were published by Tokuda et al. (2014). Matsumoto et al. (2015) investigated the arc-like structures by performing numerical simulations.Detailed column density distribution with the size from ~100 to ~10000 AU scale are revealed by combining the 12m array data with the 7m array data of the ALMA Compact Array as well as with the single dish MAMBO data. Our preliminary analysis shows that the averaged radial column density distribution of the inner part (r < 2000 AU) is N(H2)~r-0.4, clearly flatter than that of the outer part, ~r-1.3. We detected the above-mentioned complex structure inside the inner flatter region, which may reflect the dynamical status of the dense core. The Cycle 1

  8. Strengthening lightweight concrete

    NASA Technical Reports Server (NTRS)

    Auskern, A.

    1972-01-01

    Polymer absorption by lightweight concretes to improve bonding between cement and aggregate and to increase strength of cement is discussed. Compressive strength of treated cement is compared with strength of untreated product. Process for producing polymers is described.

  9. Concrete production floating platforms

    SciTech Connect

    Letourneur, O.; Falcimaigne, J.

    1981-01-01

    The floating production platforms operating in the North Sea are adapted from drilling semisubmersibles which allow only a limited payload capacity. Experience of concrete production platforms constructed for the North Sea has led Sea Tank Co. to propose a floating platform which offers large payload and oil storage capacities similar to those of existing fixed platforms. Sea Tank Co. and Institut Francais du Petrole joined forces in early 1976 to study the feasibility of a concrete floating production platform incorporating the structure and the production riser together. The results of this 3-yr program show that the concrete floating structure is economically attractive for permanent utilization on a production site. Furthermore, concrete has definite advantages over other materials, in its long term behavior.

  10. Concrete decontamination scoping tests

    SciTech Connect

    Archibald, K.E.

    1995-01-01

    This report details the research efforts and scoping tests performed at the Idaho Chemical Process Plant using scabbling, chemical, and electro-osmotic decontamination techniques on radiologically contaminated concrete.

  11. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  12. Magnetic field assisted self-assembly of ferrite-ferroelectric core-shell nanofibers and studies on magneto-electric interactions

    SciTech Connect

    Sreenivasulu, G.; Zhang, Ru; Sharma, K.; Janes, C.; Mukundan, A.; Srinivasan, G.; Popov, Maksym

    2014-02-03

    Core-shell nanofibers of nickel ferrite and lead zirconate titanate have been synthesized by electrospinning, assembled into superstructure in uniform or non-uniform magnetic fields, and have been characterized in terms of ferroic order parameters and strain mediated magneto-electric (ME) coupling. The core-shell structure was confirmed by electron microscopy and scanning probe microscopy. Studies on magnetic field induced polarization P in assembled samples showed a decrease or increase in P, depending on the nature of fibers and strengthening of ME coupling with change in remnant-P as high as 32%. Strong ME interactions were evident from H-induced variation in permittivity at 20–22 GHz.

  13. Diagnosing delayed ettringite formation in concrete structures

    SciTech Connect

    Thomas, Michael Folliard, Kevin Drimalas, Thano Ramlochan, Terry

    2008-06-15

    There has been a number of cases involving deteriorated concrete structures in North America where there has been considerable controversy surrounding the respective contributions of alkali-silica reaction (ASR) and delayed ettringite formation (DEF) to the observed damage. The problem arises because the macroscopic symptoms of distress are not unequivocal and microscopical examinations of field samples often reveal evidence of both processes making it difficult to separate the individual contributions. This paper presents the results of an investigation of a number of concrete columns carrying a raised expressway in North America; prior studies had implicated both DEF and ASR as possible causes of deterioration. Although the columns were not deliberately heat-cured, it is estimated that the peak internal temperature would have exceeded 70 deg. C and perhaps even 80 deg. C, in some cases. The forensic investigation included scanning electron microscopy with energy-dispersive X-ray analysis and expansion testing of cores extracted from the structure. Small-diameter cores stored in limewater expanded significantly (0.3 to 1.3%) and on the basis of supplementary tests on laboratory-produced concrete specimens it was concluded that expansion under such conditions is caused by DEF as the conditions of the test will not sustain ASR. In at least one column, DEF was diagnosed as the sole contributory cause of damage with no evidence of any contribution from ASR or any other deterioration process. In other cases, both ASR and DEF were observed to have contributed to the apparent damage. Of the columns examined, only concrete containing fly ash appeared to be undamaged. The results of this study confirm that, under certain conditions, the process of DEF (acting in isolation of other processes) can result in significant deterioration of cast-in-place reinforced concrete structures.

  14. Shear Resistance between Concrete-Concrete Surfaces

    NASA Astrophysics Data System (ADS)

    Kovačovic, Marek

    2013-12-01

    The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

  15. Unliganded HIV-1 gp120 core structures assume the CD4-bound conformation with regulation by quaternary interactions and variable loops

    SciTech Connect

    Kwon, Young Do; Finzi, Andrés; Wu, Xueling; Dogo-Isonagie, Cajetan; Lee, Lawrence K.; Moore, Lucas R.; Schmidt, Stephen D.; Stuckey, Jonathan; Yang, Yongping; Zhou, Tongqing; Zhu, Jiang; Vicic, David A.; Debnath, Asim K.; Shapiro, Lawrence; Bewley, Carole A.; Mascola, John R.; Sodroski, Joseph G.; Kwong, Peter D.

    2013-03-04

    The HIV-1 envelope (Env) spike (gp120{sub 3}/gp41{sub 3}) undergoes considerable structural rearrangements to mediate virus entry into cells and to evade the host immune response. Engagement of CD4, the primary human receptor, fixes a particular conformation and primes Env for entry. The CD4-bound state, however, is prone to spontaneous inactivation and susceptible to antibody neutralization. How does unliganded HIV-1 maintain CD4-binding capacity and regulate transitions to the CD4-bound state? To define this mechanistically, we determined crystal structures of unliganded core gp120 from HIV-1 clades B, C, and E. Notably, all of these unliganded HIV-1 structures resembled the CD4-bound state. Conformational fixation with ligand selection and thermodynamic analysis of full-length and core gp120 interactions revealed that the tendency of HIV-1 gp120 to adopt the CD4-bound conformation was restrained by the V1/V2- and V3-variable loops. In parallel, we determined the structure of core gp120 in complex with the small molecule, NBD-556, which specifically recognizes the CD4-bound conformation of gp120. Neutralization by NBD-556 indicated that Env spikes on primary isolates rarely assume the CD4-bound conformation spontaneously, although they could do so when quaternary restraints were loosened. Together, the results suggest that the CD4-bound conformation represents a 'ground state' for the gp120 core, with variable loop and quaternary interactions restraining unliganded gp120 from 'snapping' into this conformation. A mechanism of control involving deformations in unliganded structure from a functionally critical state (e.g., the CD4-bound state) provides advantages in terms of HIV-1 Env structural diversity and resistance to antibodies and inhibitors, while maintaining elements essential for entry.

  16. Performance of "Waterless Concrete"

    NASA Technical Reports Server (NTRS)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  17. Use of cactus in mortars and concrete

    SciTech Connect

    Chandra, S.; Eklund, L.; Villarreal, R.R.

    1998-01-01

    Natural polymers have been used in ancient times to improve the durability of lime-based mortars and concretes. The natural polymers used were locally available. In this work, cactus extract from Mexico has been tested in a Portland cement mortar. It is seen that cactus extract increases the plasticity of the mortar and improves water absorption and freeze-salt resistance. Calcium hydroxide produced by Portland cement hydration interacts with the components of cactus extract, polysaccharides or proteins, and forms complexes. It affects the crystallization process. Painting of the concrete with this extract has also shown improved water resistance.

  18. Radiogenic isotopic constraints from the Project Hotspot Kimama core: implications for Hotspot-controlled lithosphere interactions beneath the Snake River Plain

    NASA Astrophysics Data System (ADS)

    Potter, K. E.; Hanan, B. B.; Shervais, J. W.

    2013-12-01

    Project Hotspot, the Snake River Scientific Drilling Project, seeks to understand the evolution of Snake River Plain -Yellowstone Plateau volcanism through time. Radiogenic isotope chemistry, paleomagnetic stratigraphy, and 40Ar/39Ar geochronology from the Kimama core temporally constrain the mass proportions and flux of magma source components in Snake River Plain-Yellowstone Plateau (SRP-YP) basaltic volcanism. We present new radiogenic isotope data for the Kimama core of the central Snake River Plain that support the regional model of plume-continental lithosphere interaction and westward source variation over the past ~ 12 Ma. The 1912 m Kimama core provides a nearly continuous depositional record of basaltic lava flows on the central Snake River Plain from the late Miocene through Pleistocene. Most of the basalt flows are Snake River olivine tholeiites with MgO 6-10%, Fe2O3 < 16%, and K2O <0.9%. Compositionally evolved basalts similar to those erupted at Craters of the Moon (high K2O, Fe2O3, and Zr) were identified at various depths throughout the core. We analyzed 15 basalt samples from a range of geochemical compositions and depths within the Kimama core for Nd, Sr, Hf, and Pb. Radiogenic Pb isotope values for Kimama basalts ranged from 206Pb/204Pb ~18.0--18.5, 207Pb/204Pb ~15.6--15.7, and 208Pb/204Pb ~38.5--39.0. Radiogenic Hf isotopes range from 0.282683--0.282745. Evolved basalts span the same range of 177Hf/176Hf, 207Pb/204Pb, and 208Pb/204Pb as the more primitive basalt compositions (high MgO, Cr, and Ni). Ar/Ar and paleomagnetic dating establish a relatively linear basalt accumulation rate of 305 m/m.y. and a projected bottom hole age of 6.2 Ma.

  19. Mobility of chelated radionuclides in engineered concrete barriers

    SciTech Connect

    Dicke, C.A.; Smith, R.W.

    1993-12-31

    Concrete is a major component in many low-level radioactive waste (LLW) disposal facilities. The use of concrete is widespread because of its physical and structural properties and because it provides geochemical control on metal and radionuclide releases. Organic compounds are often disposed with radionuclides in LLW disposal facilities. Interactions between radionuclides and chelating agents must be evaluated to estimate mobility of radionuclides in concrete vaults. This paper quantifies the effects of two common organic components [citric acid and ethylenediaminetetraacetic acid (EDTA)] on radionuclide mobility in concrete barriers by using equilibrium geochemical calculations. Equilibrium speciation calculations indicate that some radionuclides are chelated in groundwater (pH 7) but are destabilized in the highly alkaline (pH 13) concrete pore fluids. Radionuclides complexed by by EDTA and citrate are replaced by calcium in the concrete pore fluids. In addition, the citrate nuclide complex reacts to form uncomplexed citrate in concrete pore fluids. The chemical performance of concrete LLW disposal facilities should not be compromised by small amounts of chelating agents disposed with some radionuclides. However, EDTA may form significant nickel and cobalt complexes above the pH important in the long-term service life of concrete barriers.

  20. A Green Function Approach to the Effects of Core-state Overlap on Interatomic Interactions at Extreme Densities

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Stocks, G. Malcolm

    Under extreme conditions of temperature and pressure, interatomic separations in condensed matter can approach a small fraction of those under normal laboratory conditions. For example, during high-energy (~ 100 keV) radiation damage cascades, interatomic separations can be as small as 0.5Å. Under such conditions, core states between neighboring atoms could overlap and must be included as band states. Here we use Green's function method in the framework of multiple scattering theory, also known as Korringa-Kohn-Rostoker (KKR) electronic structure methods, to seamlessly integrate these core overlap effects within an all-electron ab initio approach. To accomplish these we use multiple integration contours in the complex plane that incorporate states normally treated as bound atomic levels. We show results for Ni and NiFe alloys in extreme densities (a /a0 ~ 0 . 3) to illustrate the convergence of the method with respect to which core states are banded as well as the angular moment cut-off required to establish absolute convergence of the total energies. Results are compared with those of plane-wave methods for different choices of the underlying pseudo potential to establish the range of validity of the various approaches.

  1. The human core exosome interacts with differentially localized processive RNases: hDIS3 and hDIS3L.

    PubMed

    Tomecki, Rafal; Kristiansen, Maiken S; Lykke-Andersen, Søren; Chlebowski, Aleksander; Larsen, Katja M; Szczesny, Roman J; Drazkowska, Karolina; Pastula, Agnieszka; Andersen, Jens S; Stepien, Piotr P; Dziembowski, Andrzej; Jensen, Torben Heick

    2010-07-21

    The eukaryotic RNA exosome is a ribonucleolytic complex involved in RNA processing and turnover. It consists of a nine-subunit catalytically inert core that serves a structural function and participates in substrate recognition. Best defined in Saccharomyces cerevisiae, enzymatic activity comes from the associated subunits Dis3p (Rrp44p) and Rrp6p. The former is a nuclear and cytoplasmic RNase II/R-like enzyme, which possesses both processive exo- and endonuclease activities, whereas the latter is a distributive RNase D-like nuclear exonuclease. Although the exosome core is highly conserved, identity and arrangements of its catalytic subunits in different vertebrates remain elusive. Here, we demonstrate the association of two different Dis3p homologs--hDIS3 and hDIS3L--with the human exosome core. Interestingly, these factors display markedly different intracellular localizations: hDIS3 is mainly nuclear, whereas hDIS3L is strictly cytoplasmic. This compartmental distribution reflects the substrate preferences of the complex in vivo. Both hDIS3 and hDIS3L are active exonucleases; however, only hDIS3 has retained endonucleolytic activity. Our data suggest that three different ribonucleases can serve as catalytic subunits for the exosome in human cells. PMID:20531386

  2. The agricultural history of human-nitrogen interactions as recorded in ice core δ15N-NO3-

    NASA Astrophysics Data System (ADS)

    Felix, J. David; Elliott, Emily M.

    2013-04-01

    The advent and industrialization of the Haber Bosch process in the early twentieth century ushered in a new era of reactive nitrogen distributions on Earth. Since the appearance of the first commercial scale Haber Bosch fertilizer plants, fertilizer application rates have greatly increased in the U.S. While the contributions of fertilizer runoff to eutrophication and anoxic dead zones in coastal regions have been well-documented, the potential influences of increased fertilizer applications on air quality and precipitation chemistry are poorly constrained. Here we combine a 255-year record of precipitation nitrate isotopes preserved in a Greenland ice core, historical reconstructions of fertilizer application rates, and field characterization of the isotopic composition of nitrogen oxides produced biogenically in soils, to provide new constraints on the contributions of biogenic emissions to North American NOx inventories. Our results indicate that increases in twentieth century commercial fertilizer use led to large increases in soil NO, a byproduct released during nitrification and denitrification reactions. These large shifts in soil NO production are evidenced by sharp declines in ice core δ15N-NO3- values. Further, these results suggest that biogenic NOx emissions are underestimated by two to four fold in the U.S. NOx emission inventories used to construct global reactive nitrogen budgets. These results demonstrate that nitrate isotopes in ice cores, coupled with newly constrained δ15N-NOx values for NOx emission sources, provide a novel means for estimating contemporary and historic contributions from individual NOx emission sources to deposition.

  3. Porosity estimation of concrete by ultrasonic NDE

    PubMed

    Hernandez; Izquierdo; Ibanez; Anaya; Ullate

    2000-03-01

    The increasing number of concrete structures with symptoms of premature deterioration due to environmental action demands procedures to estimate the durability of this type of component. Concrete durability is related to porosity, which determines the intensity of interactions of the material with aggressive agents. The pores and capillaries inside the structure facilitate the destructive processes that generally begin in the surface. In this work, an ultrasonic NDE technique to estimate the porosity of concrete is developed. The method is based on the analysis of the mechanical behaviour of mortar probes built with calibrated sand, in which the concentration of water-cement mixture has been varied. In this sense, data of sound velocity are correlated with data of porosity, which have been previously measured by destructive measurements. PMID:10829720

  4. Evaluation of irradiation effects on concrete structure

    SciTech Connect

    Kontani, O.; Ishizawa, A.; Maruyama, I.; Takizawa, M.; Sato, O.

    2012-07-01

    In assessing the soundness of irradiated concrete of nuclear power plants operated for more than 30 years, reference levels are employed: 1x10{sup 20} n/cm{sup 2} for fast neutrons and 2x10{sup 10} rad (2x10{sup 5} kGy) for gamma rays. Concrete structures are regarded as sound when the estimated irradiance levels after 60 years of operation are less than the reference levels. The reference levels were obtained from a paper by Hilsdorf. It was found, however, that the test conditions in which data were obtained by the researchers referred in that paper are very different from the irradiation and heat conditions usually found in a Light Water Reactor (LWR), and therefore aren't appropriate for assessing the soundness of irradiated concrete of an LWR. This paper investigates the interactions between radiation and concrete and presents the results of gamma ray irradiation tests on cement paste samples in order to provide a better understanding of the irradiation effects on concrete. (authors)

  5. Inspection of prestressed concrete pressure pipe

    NASA Astrophysics Data System (ADS)

    Atherton, D. L.; Morton, K. J.; Mergelas, B. J.; Kong, X.

    2000-05-01

    A new electromagnetic technique for inspecting prestressed concrete pressure pipe (CPP) for broken prestressing wires is described. CPP is used for water supply lines, power station cooling loops and waste water force lines. The smaller lined cylinder pipes have diameters 400-1200 mm. They have a thin steel cylinder with an inner centrifugally cast concrete core 25-50 mm thick. After curing, high strength prestressing wire is spirally wound, under high tension, onto the steel cylinder. A protective mortar coating is then impacted. Embedded-cylinder pipes have diameters 1.2-7 m. Their construction is similar but they have an additional 80-130 mm layers of concrete cast outside the steel cylinder before the prestressing wire is wound on. The pitch and gage of the wire is chosen to ensure that the concrete is always under compression. The new inspection technique uses a combination of remote field eddy current and transformer coupling effects to detect broken prestressing wires. The tools can access large pipes through small diameter man holes. They can detect single or multiple breaks in the prestressing wire at any point on the circumference and are drawn through a pipe at walking speed. The principles of operation and inspection results are described.

  6. Interaction between lamellar twinning and catalyst dynamics in spontaneous core-shell InGaP nanowires

    NASA Astrophysics Data System (ADS)

    Oliveira, D. S.; Tizei, L. H. G.; Li, A.; Vasconcelos, T. L.; Senna, C. A.; Archanjo, B. S.; Ugarte, D.; Cotta, M. A.

    2015-07-01

    Semiconductor nanowires oriented along the [211] direction usually present twins parallel to their axis. For group IV nanowires this kind of twin allows the formation of a catalyst-nanowire interface composed of two equivalent {111} facets. For III-V nanowires, however, the twin will generate two facets with different polarities. In order to keep the <211> orientation stable, a balance in growth rates for these different facets must be reached. We report here the observation of stable, micron-long <211>-oriented InGaP nanowires with a spontaneous core-shell structure. We show that stacking fault formation in the crystal region corresponding to the {111}A facet termination provides a stable NW/NP interface for growth along the <211> direction. During sample cool down, however, the catalyst migrates to a lateral {111}B facet, allowing the growth of branches perpendicular to the initial orientation. In addition to that, we show that the core-shell structure is non-concentric, most likely due to the asymmetry between the facets formed in the NW sidewall; this effect generates stress along the nanowire, which can be relieved through bending.Semiconductor nanowires oriented along the [211] direction usually present twins parallel to their axis. For group IV nanowires this kind of twin allows the formation of a catalyst-nanowire interface composed of two equivalent {111} facets. For III-V nanowires, however, the twin will generate two facets with different polarities. In order to keep the <211> orientation stable, a balance in growth rates for these different facets must be reached. We report here the observation of stable, micron-long <211>-oriented InGaP nanowires with a spontaneous core-shell structure. We show that stacking fault formation in the crystal region corresponding to the {111}A facet termination provides a stable NW/NP interface for growth along the <211> direction. During sample cool down, however, the catalyst migrates to a lateral {111}B facet, allowing

  7. Defect induced ferromagnetic interaction in nanostructured nickel oxide with core-shell magnetic structure: the role of Ni(2+) and O(2-) vacancies.

    PubMed

    Madhu, G; Maniammal, K; Biju, V

    2016-04-28

    Nanostructured nickel oxide samples with crystallite sizes in the range 32-45 nm are synthesized through a facile chemical route using nickel chloride and ethanol amine as the starting materials. The analysis of the antioxidant activity and DC conductivity of the NiO samples confirmed the presence of both Ni(2+) and O(2-) vacancies. The temperature dependent magnetization studies of the samples are done using a Vibrating Sample Magnetometer in the range 20-300 K. The core-shell magnetic structure of the NiO nanoparticles with an antiferromagnetic core and a spin-glass shell is revealed from the zero field cooled and field cooled magnetization studies of the samples. The dependence of uncompensated moments on total spins contradicts Neel's models and is found to vary directly with O(2-) vacancy concentration. The ferromagnetic response of NiO samples due to the interaction between the antiferromagnetic core and the ferromagnetic shell is evident from the magnetic hysteresis studies in the temperature range 20-300 K. The ferromagnetic response is traced to the concentration of O(2-) vacancies, which act as donor impurities and mediate the alignment of magnetic moments associated with Ni(2+) vacancies. The decrease of ferromagnetic contribution upon annealing is explained by the decrease in the concentration of O(2-) vacancies which caused a reduction in the number of magnetic polarons and hence the effective magnetization. PMID:27074902

  8. Cationic Ionic Liquids Organic Ligands Based Metal-Organic Frameworks for Fabrication of Core-Shell Microspheres for Hydrophilic Interaction Liquid Chromatography.

    PubMed

    Dai, Qian; Ma, Junqian; Ma, Siqi; Wang, Shengyu; Li, Lijun; Zhu, Xianghui; Qiao, Xiaoqiang

    2016-08-24

    In this study, new metal-organic frameworks (MOFs) nanocrystals modified SiO2 core-shell microspheres were designed with cationic ionic liquids (ILs) 1,3-bis(4-carboxybutyl)imidazolium bromide (ILI) as organic ligands. By further adjustment the growth cycles, the new ILI-01@SiO2 core-shell stationary phase was facilely fabricated. The developed stationary phase was respectively characterized via element analysis, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry. Because the introduction of cationic imidazolium-based ILs ILI for fabrication of the MOFs nanocrystals shell, the new stationary phase exhibits the retention mechanism of hydrophilic interaction liquid chromatography (HILIC). Many polar samples, such as amides, vitamins, nucleic acid bases, and nucleosides, were utilized to investigate the performance of the prepared ILI-01@SiO2 column. Compared to the conventional aminosilica column, the new ILI-01@SiO2 column displays high separation selectivity in a shorter separation time. Furthermore, the new ILI-01@SiO2 column was also used for detection of illegal melamine addition in the baby formula. All the above results demonstrate the new ILI-01@SiO2 core-shell stationary phase is of good potentials for high-selectivity separation the polar samples. PMID:27483161

  9. Insight on the Interaction of Methanol-Selective Oxidation Intermediates with Au- or/and Pd-Containing Monometallic and Bimetallic Core@Shell Catalysts.

    PubMed

    Czelej, Kamil; Cwieka, Karol; Colmenares, Juan Carlos; Kurzydlowski, Krzysztof J

    2016-08-01

    Using density functional theory (DFT), the interaction of crucial molecules involved in the selective partial oxidation of methanol to methyl formate (MF) with monometallic Au and Pd and bimetallic Au/Pd and Pd/Au core@shell catalysts is systematically investigated. The core@shell structures modeled in this study consist of Au(111) and Pd(111) cores covered by a monolayer of Pd and Au, respectively. Our results indicate that the adsorption strength of the molecules examined as a function of catalytic surface decreases in the order of Au/Pd(111) > Pd(111) > Au(111) > Pd/Au(111) and correlates well with the d-band center model. The preadsorption of oxygen is found to have a positive impact on the selective partial oxidation reaction because of the stabilization of CH3OH and HCHO on the catalyst surface and the simultaneous intensification of MF desorption. On the basis of a dynamical matrix approach combined with statistical thermodynamics, we propose a simple route for evaluating the Gibbs free energy of adsorption as a function of temperature. This method allows us to anticipate the relative temperature stability of molecules involved in the selective partial oxidation of methanol to MF in terms of catalytic surface. PMID:27373791

  10. Site- and geometry-specific CH...O interaction in small acetaldehyde clusters studied with core-electron excitation spectroscopy in the carbon K-edge region

    NASA Astrophysics Data System (ADS)

    Tabayashi, K.; Tsutsumi, Y.; Chohda, M.; Takahashi, O.; Tamenori, Y.; Higuchi, I.; Suzuki, I. H.; Nagaoka, S.; Gejo, T.; Honma, K.

    2011-04-01

    Site-dependent C1s-core excitation spectra of small acetaldehyde (AAL) clusters have been studied under the cluster regime of beam conditions. The excitation spectra of the clusters were generated by monitoring the partial-ion-yields of cluster-origin fragments. Comparison of the cluster bands with the monomer bands revealed that the band intensities of C1s core-to-Rydberg transitions come to be strongly excitation-site dependent upon cluster formation showing significant reduction of C1sHCO→Ryd bands relative to the monomer bands. Computer modeling of X-ray absorption spectra using a density functional theory calculation demonstrated that the intensity reduction is the outcome of the site- and geometry-specific CH...O interaction where hydrogen-bonding association between the aldehyde (HCO) sites of different AAL molecules takes place exclusively within the clusters. As the representatives of small AAL clusters (n>=3), two types of molecular complexes (a planar cyclic trimer and a tetramer with a stack of two dimers) were derived to rationalize the site-dependence of the experimental C1s excitation spectra. Spectral simulation of the above complexes could reproduce the experimental site-dependence of the core-to-Rydberg band-features upon clusterization, indicative of significant contribution of these clusters under the present beam-stagnation condition.