Science.gov

Sample records for element response surfaces

  1. Vortex shedding and morphodynamic response of bed surfaces containing non-erodible roughness elements

    NASA Astrophysics Data System (ADS)

    McKenna Neuman, Cheryl; Sanderson, Robert Steven; Sutton, Stephen

    2013-09-01

    A series of wind tunnel experiments was carried out to investigate particle entrainment from surfaces in which one or more roughness elements were embedded. Thin sand strips were employed to eliminate impact and ejection, and thus isolate entrainment by fluid drag. The pattern of erosion is consistent with the presence of coherent vortices, inclusive of trailing vortices in the wake flow. The shape and orientation of the roughness element strongly influence this pattern. When an upwind supply of saltators is introduced, the majority of particles within the bed are entrained through impact, with the exception of a sand tail to the lee of the roughness element. That is, the effect of coherent structures within the airflow, as related to spatial variation in the fluid drag exerted on the bed surface, is completely overprinted by the saltation cloud and the blocking of particle trajectories by the upwind face of the roughness element. In a repeated set of experiments, the bed was allowed to fully adjust its morphology to the transport system. In this case, particle entrainment did not selectively occur within the zone of wake flow, and by inference the fluid stress across the test surface appeared to be uniform. These experiments support the hypothesis that vortex annihilation occurs on morphodynamically adjusted surfaces. In summary, the system response to the emergence of non-erodible roughness elements on surfaces affected by wind erosion involves a suite of geophysical processes, each of which attains varied levels of dominance within a given morphodynamic domain.

  2. Finite-element/progressive-lattice-sampling response surface methodology and application to benchmark probability quantification problems

    SciTech Connect

    Romero, V.J.; Bankston, S.D.

    1998-03-01

    Optimal response surface construction is being investigated as part of Sandia discretionary (LDRD) research into Analytic Nondeterministic Methods. The goal is to achieve an adequate representation of system behavior over the relevant parameter space of a problem with a minimum of computational and user effort. This is important in global optimization and in estimation of system probabilistic response, which are both made more viable by replacing large complex computer models with fast-running accurate and noiseless approximations. A Finite Element/Lattice Sampling (FE/LS) methodology for constructing progressively refined finite element response surfaces that reuse previous generations of samples is described here. Similar finite element implementations can be extended to N-dimensional problems and/or random fields and applied to other types of structured sampling paradigms, such as classical experimental design and Gauss, Lobatto, and Patterson sampling. Here the FE/LS model is applied in a ``decoupled`` Monte Carlo analysis of two sets of probability quantification test problems. The analytic test problems, spanning a large range of probabilities and very demanding failure region geometries, constitute a good testbed for comparing the performance of various nondeterministic analysis methods. In results here, FE/LS decoupled Monte Carlo analysis required orders of magnitude less computer time than direct Monte Carlo analysis, with no appreciable loss of accuracy. Thus, when arriving at probabilities or distributions by Monte Carlo, it appears to be more efficient to expend computer-model function evaluations on building a FE/LS response surface than to expend them in direct Monte Carlo sampling.

  3. Application of finite element, global polynomial, and kriging response surfaces in Progressive Lattice Sampling designs

    SciTech Connect

    ROMERO,VICENTE J.; SWILER,LAURA PAINTON; GIUNTA,ANTHONY A.

    2000-04-25

    This paper examines the modeling accuracy of finite element interpolation, kriging, and polynomial regression used in conjunction with the Progressive Lattice Sampling (PLS) incremental design-of-experiments approach. PLS is a paradigm for sampling a deterministic hypercubic parameter space by placing and incrementally adding samples in a manner intended to maximally reduce lack of knowledge in the parameter space. When combined with suitable interpolation methods, PLS is a formulation for progressive construction of response surface approximations (RSA) in which the RSA are efficiently upgradable, and upon upgrading, offer convergence information essential in estimating error introduced by the use of RSA in the problem. The three interpolation methods tried here are examined for performance in replicating an analytic test function as measured by several different indicators. The process described here provides a framework for future studies using other interpolation schemes, test functions, and measures of approximation quality.

  4. Senescence responsive transcriptional element

    DOEpatents

    Campisi, Judith; Testori, Alessandro

    1999-01-01

    Recombinant polynucleotides have expression control sequences that have a senescence responsive element and a minimal promoter, and which are operatively linked to a heterologous nucleotide sequence. The molecules are useful for achieving high levels of expression of genes in senescent cells. Methods of inhibiting expression of genes in senescent cells also are provided.

  5. Senescence responsive transcriptional element

    SciTech Connect

    Campisi, J.; Testori, A.

    1999-10-12

    Recombinant polynucleotides have expression control sequences that have a senescence responsive element and a minimal promoter, and which are operatively linked to a heterologous nucleotide sequence. The molecules are useful for achieving high levels of expression of genes in senescent cells. Methods of inhibiting expression of genes in senescent cells also are provided.

  6. Surface energies of elemental crystals.

    PubMed

    Tran, Richard; Xu, Zihan; Radhakrishnan, Balachandran; Winston, Donald; Sun, Wenhao; Persson, Kristin A; Ong, Shyue Ping

    2016-01-01

    The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal's equilibrium shape. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. In this work, we present the largest database of calculated surface energies for elemental crystals to date. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. Well-known reconstruction schemes are also accounted for. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials. PMID:27622853

  7. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.; Mary, Natalie; Howe, A. Scott; Jeffries, Sharon

    2016-01-01

    How Mars surface crews get into their ascent vehicle has profound implications for Mars surface architecture. To meet planetary protection protocols, the architecture has get Intravehicular Activity (IVA)-suited crew into a Mars Ascent Vehicle (MAV) without having to step outside into the Mars environment. Pushing EVA suit don/doff and EVA operations to an element that remains on the surface also helps to minimize MAV cabin volume, which in turn can reduce MAV cabin mass. Because the MAV will require at least seven kilograms of propellant to ascend each kilogram of cabin mass, minimal MAV mass is desired. For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The "Minimum Functional Tunnel" is a conceptual design that performs a single function. Having established this baseline configuration, the next step is to trade design options, evaluate other applications, and explore alternative solutions.

  8. Surface energies of elemental crystals

    PubMed Central

    Tran, Richard; Xu, Zihan; Radhakrishnan, Balachandran; Winston, Donald; Sun, Wenhao; Persson, Kristin A.; Ong, Shyue Ping

    2016-01-01

    The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal’s equilibrium shape. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. In this work, we present the largest database of calculated surface energies for elemental crystals to date. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. Well-known reconstruction schemes are also accounted for. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials. PMID:27622853

  9. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.

    2016-01-01

    How crews get into or out of their ascent vehicle has profound implications for Mars surface architecture. Extravehicular Activity (EVA) hatches and Airlocks have the benefit of relatively low mass and high Technology Readiness Level (TRL), but waste consumables with a volume depressurization for every ingress/egress. Perhaps the biggest drawback to EVA hatches or Airlocks is that they make it difficult to keep Martian dust from being tracked back into the ascent vehicle, in violation of planetary protection protocols. Suit ports offer the promise of dust mitigation by keeping dusty suits outside the cabin, but require significant cabin real estate, are relatively high mass, and current operational concepts still require an EVA hatch to get the suits outside for the first EVA, and back inside after the final EVA. This is primarily because current designs don't provide enough structural support to protect the suits from ascent/descent loads or potential thruster plume impingement. For architectures involving more than one surface element-such as an ascent vehicle and a rover or surface habitat-a retractable tunnel is an attractive option. By pushing spacesuit don/doff and EVA operations to an element that remains on the surface, ascended vehicle mass and dust can be minimized. What's more, retractable tunnels provide operational flexibility by allowing surface assets to be re-configured or built up over time. Retractable tunnel functional requirements and design concepts being developed as part of the National Aeronautics and Space Administration's (NASA) Evolvable Mars Campaign (EMC) work will add a new ingress/egress option to the surface architecture trade space.

  10. Mars Surface Tunnel Element Concept

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.; Jefferies, Sharon; Howe, A. Scott; Howard, Robert; Mary, Natalie; Watson, Judith; Lewis, Ruthan

    2016-01-01

    When the first human visitors on Mars prepare to return to Earth, they will have to comply with stringent planetary protection requirements. Apollo Program experience warns that opening an EVA hatch directly to the surface will bring dust into the ascent vehicle. To prevent inadvertent return of potential Martian contaminants to Earth, careful consideration must be given to the way in which crew ingress their Mars Ascent Vehicle (MAV). For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel that eliminates extravehicular activity (EVA) ingress is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications, such as rover to habitat transfer, once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The study team began by identifying the minimum set of functional requirements needed for the tunnel to perform its primary mission, as this would presumably be the simplest design, with the lowest mass and volume. This Minimum Functional Tunnel then becomes a baseline against which various tunnel design concepts and potential alternatives can be traded, and aids in assessing the mass penalty of increased functionality. Preliminary analysis indicates that the mass of a single-mission tunnel is about 237 kg, not including mass growth allowance.

  11. Progressive Response Surfaces

    NASA Technical Reports Server (NTRS)

    Romero, V. J.; Swiler, L. P.

    2004-01-01

    Response surface functions are often used as simple and inexpensive replacements for computationally expensive computer models that simulate the behavior of a complex system over some parameter space. Progressive response surfaces are ones that are built up progressively as global information is added from new sample points in the parameter space. As the response surfaces are globally upgraded based on new information, heuristic indications of the convergence of the response surface approximation to the exact (fitted) function can be inferred. Sampling points can be incrementally added in a structured fashion, or in an unstructured fashion. Whatever the approach, at least in early stages of sampling it is usually desirable to sample the entire parameter space uniformly. At later stages of sampling, depending on the nature of the quantity being resolved, it may be desirable to continue sampling uniformly over the entire parameter space (Progressive response surfaces), or to switch to a focusing/economizing strategy of preferentially sampling certain regions of the parameter space based on information gained in early stages of sampling (Adaptive response surfaces). Here we consider Progressive response surfaces where a balanced indication of global response over the parameter space is desired.We use a variant of Moving Least Squares to fit and interpolate structured and unstructured point sets over the parameter space. On a 2-D test problem we compare response surface accuracy for three incremental sampling methods: Progressive Lattice Sampling; Simple-Random Monte Carlo; and Halton Quasi-Monte-Carlo sequences. We are ultimately after a system for constructing efficiently upgradable response surface approximations with reliable error estimates.

  12. Uncovering drug-responsive regulatory elements

    PubMed Central

    Luizon, Marcelo R; Ahituv, Nadav

    2016-01-01

    Nucleotide changes in gene regulatory elements can have a major effect on interindividual differences in drug response. For example, by reviewing all published pharmacogenomic genome-wide association studies, we show here that 96.4% of the associated single nucleotide polymorphisms reside in noncoding regions. We discuss how sequencing technologies are improving our ability to identify drug response-associated regulatory elements genome-wide and to annotate nucleotide variants within them. We highlight specific examples of how nucleotide changes in these elements can affect drug response and illustrate the techniques used to find them and functionally characterize them. Finally, we also discuss challenges in the field of drug-responsive regulatory elements that need to be considered in order to translate these findings into the clinic. PMID:26555224

  13. Algebraic surface design and finite element meshes

    NASA Technical Reports Server (NTRS)

    Bajaj, Chandrajit L.

    1992-01-01

    Some of the techniques are summarized which are used in constructing C sup 0 and C sup 1 continuous meshes of low degree, implicitly defined, algebraic surface patches in three dimensional space. These meshes of low degree algebraic surface patches are used to construct accurate computer models of physical objects. These meshes are also used in the finite element simulation of physical phenomena (e.g., heat dissipation, stress/strain distributions, fluid flow characteristics) required in the computer prototyping of both the manufacturability and functionality of the geometric design.

  14. Surface Water Response Modeling

    EPA Science Inventory

    During response to spills, or for facility planning, the vulnerability of downstream water resources is a major concern. How long and at what concentration do spilled contaminants reach downstream receptors? Models have the potential to answer these questions, but only if they ...

  15. Finite element simulation of pipe dynamic response

    SciTech Connect

    Slagis, G.C.; Litton, R.W.

    1996-12-01

    Nonlinear finite element dynamic analyses of the response of a pipe span to controlled-displacement, sinusoidal vibration have been performed. The objective of this preliminary study is to compare strain and acceleration response data to those generated by Beaney in the Berkeley Nuclear Laboratories experiments. Results for an unpressurized, 5 Hz, carbon steel pipe are in good agreement with the experiments. Hence, it appears that analytical simulation will be useful to assess seismic margins. Recommendations for additional studies are provided. The analyses confirm the test results--dynamic response is greatly attenuated by material plasticity. Analytical strains and accelerations are about 30% higher than test data. There are several possible explanations for the differences. To assess the effect of frequency on response, the length of the pipe span was increased. Analysis of the longer, 2 Hz, pipe span shows significantly greater cyclic strains than the 5 Hz span at the same input excitation levels.

  16. Surface photovoltage measurements and finite element modeling of SAW devices.

    SciTech Connect

    Donnelly, Christine

    2012-03-01

    Over the course of a Summer 2011 internship with the MEMS department of Sandia National Laboratories, work was completed on two major projects. The first and main project of the summer involved taking surface photovoltage measurements for silicon samples, and using these measurements to determine surface recombination velocities and minority carrier diffusion lengths of the materials. The SPV method was used to fill gaps in the knowledge of material parameters that had not been determined successfully by other characterization methods. The second project involved creating a 2D finite element model of a surface acoustic wave device. A basic form of the model with the expected impedance response curve was completed, and the model is ready to be further developed for analysis of MEMS photonic resonator devices.

  17. Response surface development using RETRAN

    SciTech Connect

    Engel, R.E.; Sorensen, J.M.; May, R.S.; Doran, K.J. ); Trikouros, N.G.; Mozias, E.S. )

    1991-01-01

    The Electric Power Research Institute (EPRI) and GPU Nuclear Corporation have completed a demonstration project that provides justification for relaxing the high-pressure setpoints for the Oyster Creek Nuclear Generating Station. The project was undertaken because an undesirable overlap had been identified in the high-pressure setpoints when accounting for measurement uncertainties experienced during plant operation. The project employed a statistical combination of uncertainties (SCU) process to provide increased margin for measurement uncertainties. This approach was used because previous experience indicated that there was insufficient margin to justify the desired setpoints using conventional deterministic inputs to the safety analysis and plant performance analysis processes. Through the use of SCU methodology and other deterministic analyses, it is possible to provide comprehensive bases for the desired technical specification changes to the high-pressure setpoints. The SCU process is based on the EPRI setpoint analysis guidelines, and it requires the development of response surfaces to simulate RETRAN peak pressure calculations for the limiting transient event. The use of response surfaces adds an intermediate step to the SCU process, but reduces the number of RETRAN cases required to make appropriate statistical statements about the result probabilities. Basically, each response surface is an approximation of the RETRAN code for one particular event and one output variable of interest, which is valid over a limited region. The response surfaces can be sampled very inexpensively using simple Monte Carlo methods. The basic input to the development of a response surface is a set of results obtained from specific RETRAN cases.

  18. A robust, finite element model for hydrostatic surface water flows

    USGS Publications Warehouse

    Walters, R.A.; Casulli, V.

    1998-01-01

    A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.

  19. A remote surface pressure measurement technique for rotating elements

    SciTech Connect

    Hubner, J.P.; Abbitt, J.D.; Carroll, B.F.; Schanze, K.S.

    1997-04-01

    This technical note describes a photoluminescent paint technique developed to measure the steady-state surface pressure distributions on rotating elements. The application of pressure-sensitive paints (PSPs) as a means of measuring surface pressure has emerged in recent years as a viable alternative to conventional transducers, yielding accurate quantitative results (Morris et al., 1993; McLachlan et al., 1993; Morris, 1995). Burns and Sullivan (1995) describe a lifetime-based technique to measure pressure on rotating machinery with tip speeds exceeding 200 m/s. Their method measures the phase shift that occurs between a modulated excitation source and the corresponding emission response of the paint. The technique performed in this paper uses an unmodulated light source and measures the actual intensity decay with respect to time. The corresponding lifetimes of decay are then calibrated with the steady-state pressure.

  20. Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Chen-Tung; Kandasamy, Selvaraj

    2008-05-01

    Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

  1. Analysis of Rayleigh-Mode Spurious Response Using Finite Element Method/Spectrum Domain Analysis for Surface Acoustic Wave Resonator on Nonflat SiO2/Al/LiNbO3 Structure

    NASA Astrophysics Data System (ADS)

    Nakamura, Hiroyuki; Nakanishi, Hidekazu; Goto, Rei; Hashimoto, Ken-ya; Yamaguchi, Masatsune

    2010-07-01

    Because of their low insertion loss, high out-of-band rejection, and high power durability, miniature surface acoustic wave (SAW) duplexers are widely used in mobile phones. Substrate materials substantially limit and determine the performance of SAW duplexers; for their applications to Band I and Band IV systems with large pass-band widths and wide frequency separations between the transmitting and receiving frequency bands, a larger coupling coefficient (K2) is of primary importance. We have developed a shape-controlled SiO2 film/Al electrode/LiNbO3 substrate structure for their applications. It could lead to a large K2 and suppression of Rayleigh-mode spurious response. In this paper, we report the analysis using finite element method/spectrum domain analysis (FEM/SDA) for the SAW resonator on a nonflat SiO2 film/Al electrode/LiNbO3 structure. It was clarified that the shape-controlled SiO2 was effective in terms of achieving a large K2 for the SAW resonator with suppressed Rayleigh-mode spurious responses and bulk wave radiation. Furthermore, the experiment results showed a good agreement with the analysis results.

  2. Novel Piezoelectric Effect and Surface Plasmon Resonance-Based Elements for MEMS Applications

    PubMed Central

    Ponelyte, Sigita; Palevicius, Arvydas

    2014-01-01

    This paper covers research on novel thin films with periodical microstructure—optical elements, exhibiting a combination of piezoelectric and surface plasmon resonance effects. The research results showed that incorporation of Ag nanoparticles in novel piezoelectric—plasmonic elements shift a dominating peak in the visible light spectrum. This optical window is essential in the design of optical elements for sensing systems. Novel optical elements can be tunable under defined bias and change its main grating parameters (depth and width) influencing the response of diffraction efficiencies. These elements allow opening new avenues in the design of more sensitive and multifunctional microdevices. PMID:24747733

  3. Surface faceting and elemental diffusion behaviour at atomic scale for alloy nanoparticles during in situ annealing

    PubMed Central

    Chi, Miaofang; Wang, Chao; Lei, Yinkai; Wang, Guofeng; Li, Dongguo; More, Karren L.; Lupini, Andrew; Allard, Lawrence F.; Markovic, Nenad M.; Stamenkovic, Vojislav R.

    2015-01-01

    The catalytic performance of nanoparticles is primarily determined by the precise nature of the surface and near-surface atomic configurations, which can be tailored by post-synthesis annealing effectively and straightforwardly. Understanding the complete dynamic response of surface structure and chemistry to thermal treatments at the atomic scale is imperative for the rational design of catalyst nanoparticles. Here, by tracking the same individual Pt3Co nanoparticles during in situ annealing in a scanning transmission electron microscope, we directly discern five distinct stages of surface elemental rearrangements in Pt3Co nanoparticles at the atomic scale: initial random (alloy) elemental distribution; surface platinum-skin-layer formation; nucleation of structurally ordered domains; ordered framework development and, finally, initiation of amorphization. Furthermore, a comprehensive interplay among phase evolution, surface faceting and elemental inter-diffusion is revealed, and supported by atomistic simulations. This work may pave the way towards designing catalysts through post-synthesis annealing for optimized catalytic performance. PMID:26576477

  4. Ablative Thermal Response Analysis Using the Finite Element Method

    NASA Technical Reports Server (NTRS)

    Dec John A.; Braun, Robert D.

    2009-01-01

    A review of the classic techniques used to solve ablative thermal response problems is presented. The advantages and disadvantages of both the finite element and finite difference methods are described. As a first step in developing a three dimensional finite element based ablative thermal response capability, a one dimensional computer tool has been developed. The finite element method is used to discretize the governing differential equations and Galerkin's method of weighted residuals is used to derive the element equations. A code to code comparison between the current 1-D tool and the 1-D Fully Implicit Ablation and Thermal Response Program (FIAT) has been performed.

  5. Thresholds in shock response across the elements

    NASA Astrophysics Data System (ADS)

    Bourne, F. L.; Bourne, N. K.; CMEC Team

    2015-06-01

    Compendia of shock data have been assembled across national laboratories across the world. Previous work has shown a threshold in behaviour for materials; the weak shock limit. This corresponds the stress state at which the shock is overdriven in a single front. The shock velocity-particle velocity data for elements and compounds has been systematically analysed to note discontinuities in the data. A range of materials show these features and the form of the discontinuity in each case is analysed. Some correspond to martensitic phase transformations as expected whilst others are more difficult to track down. Particular groups within the elements show characteristic forms according to groupings in the periodic table. The datasets are presented and trends are noted.

  6. Anthropogenic disturbance of element cycles at the Earth's surface.

    PubMed

    Sen, Indra S; Peucker-Ehrenbrink, Bernhard

    2012-08-21

    The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts (Klee and Graedel, 2004). We quantify anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compare it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions, and for helium, hydrodynamic escape from the Earth's atmosphere. We introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporate uncertainties of element mass fluxes through Monte Carlo simulations. We find that at the Earth's surface anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium currently exceed natural fluxes. For these elements mining is the major factor of anthropogenic influence, whereas petroleum burning strongly influences the surficial cycle of rhenium. Our assessment indicates that if anthropogenic contributions to soil erosion and eolian dust are considered, anthropogenic fluxes of up to 62 elements surpass their corresponding natural fluxes. PMID:22803636

  7. Prediction of nuclear hormone receptor response elements.

    PubMed

    Sandelin, Albin; Wasserman, Wyeth W

    2005-03-01

    The nuclear receptor (NR) class of transcription factors controls critical regulatory events in key developmental processes, homeostasis maintenance, and medically important diseases and conditions. Identification of the members of a regulon controlled by a NR could provide an accelerated understanding of development and disease. New bioinformatics methods for the analysis of regulatory sequences are required to address the complex properties associated with known regulatory elements targeted by the receptors because the standard methods for binding site prediction fail to reflect the diverse target site configurations. We have constructed a flexible Hidden Markov Model framework capable of predicting NHR binding sites. The model allows for variable spacing and orientation of half-sites. In a genome-scale analysis enabled by the model, we show that NRs in Fugu rubripes have a significant cross-regulatory potential. The model is implemented in a web interface, freely available for academic researchers, available at http://mordor.cgb.ki.se/NHR-scan.

  8. Heat Transfer Variation on Protuberances and Surface Roughness Elements

    NASA Technical Reports Server (NTRS)

    Henry, Robert C.; Hansman, R. John, Jr.; Breuer, Kenneth S.

    1995-01-01

    In order to determine the effect of surface irregularities on local convective heat transfer, the variation in heat transfer coefficients on small (2-6 mm diam) hemispherical roughness elements on a flat plate has been studied in a wind funnel using IR techniques. Heat transfer enhancement was observed to vary over the roughness elements with the maximum heat transfer on the upstream face. This heat transfer enhancement increased strongly with roughness size and velocity when there was a laminar boundary layer on the plate. For a turbulent boundary layer, the heat transfer enhancement was relatively constant with velocity, but did increase with element size. When multiple roughness elements were studied, no influence of adjacent roughness elements on heat transfer was observed if the roughness separation was greater than approximately one roughness element radius. As roughness separation was reduced, less variation in heat transfer was observed on the downstream elements. Implications of the observed roughness enhanced heat transfer on ice accretion modeling are discussed.

  9. Finite Element Modeling of the Buckling Response of Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Rose, Cheryl A.; Moore, David F.; Knight, Norman F., Jr.; Rankin, Charles C.

    2002-01-01

    A comparative study of different modeling approaches for predicting sandwich panel buckling response is described. The study considers sandwich panels with anisotropic face sheets and a very thick core. Results from conventional analytical solutions for sandwich panel overall buckling and face-sheet-wrinkling type modes are compared with solutions obtained using different finite element modeling approaches. Finite element solutions are obtained using layered shell element models, with and without transverse shear flexibility, layered shell/solid element models, with shell elements for the face sheets and solid elements for the core, and sandwich models using a recently developed specialty sandwich element. Convergence characteristics of the shell/solid and sandwich element modeling approaches with respect to in-plane and through-the-thickness discretization, are demonstrated. Results of the study indicate that the specialty sandwich element provides an accurate and effective modeling approach for predicting both overall and localized sandwich panel buckling response. Furthermore, results indicate that anisotropy of the face sheets, along with the ratio of principle elastic moduli, affect the buckling response and these effects may not be represented accurately by analytical solutions. Modeling recommendations are also provided.

  10. Transposable elements in response to environmental stressors&

    PubMed Central

    Miousse, Isabelle R.; Chalbot, Marie-Cecile G.; Lumen, Annie; Ferguson, Alesia; Kavouras, Ilias G.; Koturbash, Igor

    2015-01-01

    Transposable elements (TEs) comprise a group of repetitive sequences that bring positive, negative, as well as neutral effects to the host organism. Earlier considered as “junk DNA,” TEs are now well-accepted driving forces of evolution and critical regulators the of expression of genetic information. Their activity is regulated by epigenetic mechanisms, including methylation of DNA and histone modifications. The loss of epigenetic control over TEs, exhibited as loss of DNA methylation and decondensation of the chromatin structure, may result in TEs reactivation, initiation of their insertional mutagenesis (retrotransposition) and has been reported in numerous human diseases, including cancer. Accumulating evidence suggests that these alterations are not the simple consequences of the disease, but often may drive the pathogenesis, as they can be detected early during disease development. Knowledge derived from the in vitro, in vivo, and epidemiological studies, clearly demonstrates that exposure to ubiquitous environmental stressors, many of which are carcinogens or suspected carcinogens, are capable of causing alterations in methylation and expression of TEs and initiate retrotransposition events. Evidence summarized in this review suggests that TEs are the sensitive endpoints for detection of effects caused by such environmental stressors, as ionizing radiation (terrestrial, space, and UV-radiation), air pollution (including particulate matter [PM]-derived and gaseous), persistent organic pollutants, and metals. Furthermore, the significance of these effects is characterized by their early appearance, persistence and presence in both, target organs and peripheral blood. Altogether, these findings suggest that TEs may potentially be introduced into safety and risk assessment and serve as biomarkers of exposure to environmental stressors. Furthermore, TEs also show significant potential to become invaluable surrogate biomarkers in clinic and possible targets

  11. Response of transposable elements to environmental stressors.

    PubMed

    Miousse, Isabelle R; Chalbot, Marie-Cecile G; Lumen, Annie; Ferguson, Alesia; Kavouras, Ilias G; Koturbash, Igor

    2015-01-01

    Transposable elements (TEs) comprise a group of repetitive sequences that bring positive, negative, as well as neutral effects to the host organism. Earlier considered as "junk DNA," TEs are now well-accepted driving forces of evolution and critical regulators of the expression of genetic information. Their activity is regulated by epigenetic mechanisms, including methylation of DNA and histone modifications. The loss of epigenetic control over TEs, exhibited as loss of DNA methylation and decondensation of the chromatin structure, may result in TEs reactivation, initiation of their insertional mutagenesis (retrotransposition) and has been reported in numerous human diseases, including cancer. Accumulating evidence suggests that these alterations are not the simple consequences of the disease, but often may drive the pathogenesis, as they can be detected early during disease development. Knowledge derived from the in vitro, in vivo, and epidemiological studies, clearly demonstrates that exposure to ubiquitous environmental stressors, many of which are carcinogens or suspected carcinogens, are capable of causing alterations in methylation and expression of TEs and initiate retrotransposition events. Evidence summarized in this review suggests that TEs are the sensitive endpoints for detection of effects caused by such environmental stressors, as ionizing radiation (terrestrial, space, and UV-radiation), air pollution (including particulate matter [PM]-derived and gaseous), persistent organic pollutants, and metals. Furthermore, the significance of these effects is characterized by their early appearance, persistence and presence in both, target organs and peripheral blood. Altogether, these findings suggest that TEs may potentially be introduced into safety and risk assessment and serve as biomarkers of exposure to environmental stressors. Furthermore, TEs also show significant potential to become invaluable surrogate biomarkers in clinic and possible targets for

  12. Design of responsive polymer surfaces with ultrafast response time

    NASA Astrophysics Data System (ADS)

    Genzer, Jan; Ozcam, Evren; Willoughby, Julie

    2009-03-01

    Responsive surfaces with tailorable surface-reconstruction kinetics and switching hysteresis were prepared from poly(vinylmethylsiloxane) (PVMS) networks modified with thiol alkanes to provide hydrophobic or hydrophilic surface properties. The cooperative effects of polymer mobility, arising from the high flexibility of the siloxane backbone, and the enthalpic interactions between the contacting medium and the PVMS functionalized surface control the degree of responsiveness. Exposing the modified-elastomer surfaces to water resulted in rearrangement of the hydrophilic alkanes at the surface. The kinetics of reconstruction and reversibility were established by measuring the surface wettability via dynamic contact angle. By controlling the formation of semi-crystalline regions in our substrates we demonstrate either ``sluggish'' kinetics and eventual surface ``freezing'' and stability or stimuli-responsive substrates with a magnitude of change and repeated reversibility unparallel to most polymeric surfaces.

  13. Anthropogenic Disturbance of Element Cycles at the Earth's Surface

    NASA Astrophysics Data System (ADS)

    Sen, I. S.; Peucker-Ehrenbrink, B.

    2012-12-01

    The extent to which humans are modifying Earth's surface chemistry can be quantified by comparing total anthropogenic element fluxes with their natural counterparts [1]. We determine anthropogenic mass transfer of 77 elements from mining, fossil fuel burning, biomass burning, construction activities, and human apportionment of terrestrial net primary productivity, and compared it to natural mass transfer from terrestrial and marine net primary productivity, riverine dissolved and suspended matter fluxes to the ocean, soil erosion, eolian dust, sea-salt spray, cosmic dust, volcanic emissions and - for helium - hydrodynamic escape from the Earth's atmosphere. In addition, we introduce an approach to correct for losses during industrial processing of elements belonging to geochemically coherent groups, and explicitly incorporated uncertainties of element mass fluxes through Monte Carlo simulations [2]. Our assessment indicates that anthropogenic fluxes of iridium, osmium, helium, gold, ruthenium, antimony, platinum, palladium, rhenium, rhodium and chromium are greater than the respective natural fluxes. For these elements mining is the major factor of human dominance, whereas petroleum burning strongly influence the surficial cycle of rhenium. Apart from these 11 elements there are 15 additional elements whose anthropogenic fluxes may surpass their corresponding natural fluxes. Anthropogenic fluxes of the remaining elements are smaller than their corresponding natural fluxes although a significant human influence is observed for all of them. For example, ~20% of the annual fluxes of C, N, and P can be attributed to human activities. Such disturbances, though small compared with natural fluxes, can significantly alter concentrations in near-surface reservoirs and affect ecosystems if they are sustained over time scales similar to or longer than the residence time of elements in the respective reservoir. Examples are the continuing input of CO2 to the atmosphere that

  14. Finite element simulation for damage detection of surface rust in steel rebars using elastic waves

    NASA Astrophysics Data System (ADS)

    Tang, Qixiang; Yu, Tzuyang

    2016-04-01

    Steel rebar corrosion reduces the integrity and service life of reinforced concrete (RC) structures and causes their gradual and sudden failures. Early stage detection of steel rebar corrosion can improve the efficiency of routine maintenance and prevent sudden failures from happening. In this paper, detecting the presence of surface rust in steel rebars is investigated by the finite element method (FEM) using surface-generated elastic waves. Simulated wave propagation mimics the sensing scheme of a fiber optic acoustic generator mounted on the surface of steel rebars. Formation of surface rust in steel rebars is modeled by changing material's property at local elements. In this paper, various locations of a fiber optic acoustic transducer and a receiver were considered. Megahertz elastic waves were used and different sizes of surface rust were applied. Transient responses of surface displacement and pressure were studied. It is found that surface rust is most detectable when the rust location is between the transducer and the receiver. Displacement response of intact steel rebar is needed in order to obtain background-subtracted response with a better signal-to-noise ratio. When the size of surface rust increases, reduced amplitude in displacement was obtained by the receiver.

  15. Non-dimensional response surfaces for structural optimization with uncertainty

    NASA Astrophysics Data System (ADS)

    Venter, Gerhardus

    Approximation concepts are an effective approach for alleviating some of the problems associated with the direct use of modern computerized analysis techniques in an optimization environment. Recently, response surface approximations have gained popularity as polynomial approximations that are global in nature. Response surface approximations shift the computational burden from the optimization problem to the problem of constructing the approximations, and accommodate the use of detailed analysis techniques without the need of derivative information. Additionally, response surface approximations filter out numerical noise inherent to most numerical analysis procedures, by providing a smooth approximate response function, and simplify the integration of the analysis and the optimization codes. The present dissertation investigates the use of response surface approximations in expensive structural optimization problems and aims to suggest techniques for improving both the accuracy of response surface approximations as well as the efficiency with which they are constructed. A stepped plate design problem is considered and response surface approximations are constructed for different failure mechanisms using numerical experiments conducted with a finite element analysis. Both an isotropic and a composite laminated plate, where the change in thickness is a result of internal ply drop off, are considered. The proposed methodology uses a combination of dimensional analysis, higher order response surface approximations, stepwise regression, a detailed error analysis and statistical design of experiments to improve both accuracy and efficiency. Dimensional analysis identifies variables intrinsic to the problem, and thus reduces the number of variables in the resulting response surface approximation. Stepwise regression is used to eliminate insignificant parameters from a response surface approximation and statistical design of experiments is used to identify a small set of

  16. Development of Biomimetic and Functionally Responsive Surfaces

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Spiros H.

    2010-03-01

    Controlling the surface morphology of solids and manufacturing of functional surfaces with special responsive properties has been the subject of intense research. We report a methodology for creating multifunctionally responsive surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with different types of functional conformal coatings. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale, which mimics the hierarchical morphology of water repellent natural surfaces. When a simple alkylsilane coating is utilized, highly water repellent surfaces are produced that quantitatively compare to those of the Lotus leaf. When a polymer brush is ``grafted from" these surfaces based on a pH-sensitive polymer, the surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). We quantify the water repellency of such responsive systems by drop elasticity measurements whereas we demonstrate that the water repellent state of such surface requires appropriate hydrophobicity of the functionalizing polymer. When a photo-responsive azobenzene-type polymer is deposited, a dynamic optical control of the wetting properties is obtained and the surface can be switched from super-hydrophilic (following UV irradiation) to hydrophobic (following green irradiation). In all the above cases we show that the principal effect of roughness is to cause amplification of the response to the different external stimuli.

  17. Environmental responses of solar reflective surfaces

    NASA Technical Reports Server (NTRS)

    Bouquet, F. L.

    1983-01-01

    An assessment is undertaken of the environmental responses of solar reflective surfaces, with emphasis on dish-type concentrator surfaces exposed to the conditions of Southern California. A generalized mathematical model for specific solar reflective surfaces can be formulated on the basis of either experimental or assumed site degradation/corrosion data. In addition, the fabrication parameters of a parabolic reflecting surface and its substrate can be used to model combined reflective characteristics for the postulated environmental conditions.

  18. Diffractive micro-optical element with nonpoint response

    NASA Astrophysics Data System (ADS)

    Soifer, Victor A.; Golub, Michael A.

    1993-01-01

    Common-use diffractive lenses have microrelief zones in the form of simple rings that provide only an optical power but do not contain any image information. They have a point-image response under point-source illumination. We must use a more complicated non-point response to focus a light beam into different light marks, letter-type images as well as for optical pattern recognition. The current presentation describes computer generation of diffractive micro- optical elements with complicated curvilinear zones of a regular piecewise-smooth structure and grey-level or staircase phase microrelief. The manufacture of non-point response elements uses the steps of phase-transfer calculation and orthogonal-scan masks generation or lithographic glass etching. Ray-tracing method is shown to be applicable in this task. Several working samples of focusing optical elements generated by computer and photolithography are presented. Using the experimental results we discuss here such applications as laser branding.

  19. Modelling cell motility and chemotaxis with evolving surface finite elements

    PubMed Central

    Elliott, Charles M.; Stinner, Björn; Venkataraman, Chandrasekhar

    2012-01-01

    We present a mathematical and a computational framework for the modelling of cell motility. The cell membrane is represented by an evolving surface, with the movement of the cell determined by the interaction of various forces that act normal to the surface. We consider external forces such as those that may arise owing to inhomogeneities in the medium and a pressure that constrains the enclosed volume, as well as internal forces that arise from the reaction of the cells' surface to stretching and bending. We also consider a protrusive force associated with a reaction–diffusion system (RDS) posed on the cell membrane, with cell polarization modelled by this surface RDS. The computational method is based on an evolving surface finite-element method. The general method can account for the large deformations that arise in cell motility and allows the simulation of cell migration in three dimensions. We illustrate applications of the proposed modelling framework and numerical method by reporting on numerical simulations of a model for eukaryotic chemotaxis and a model for the persistent movement of keratocytes in two and three space dimensions. Movies of the simulated cells can be obtained from http://homepages.warwick.ac.uk/∼maskae/CV_Warwick/Chemotaxis.html. PMID:22675164

  20. Controlled surface chemistries and quantitative cell response

    NASA Astrophysics Data System (ADS)

    Plant, Anne L.

    2002-03-01

    Living cells experience a large number of signaling cues from their extracellular matrix. As a result of these inputs, a variety of intracellular signaling pathways are apparently initiated simultaneously. The vast array of alternative responses that result from the integration of these inputs suggests that it may be reasonable to look for cellular response not as an 'on' or 'off' condition but as a distribution of responses. A difficult challenge is to determine whether variations in responses from individual cells arise from the complexity of intracellular signals or are due to variations in the cell culture environment. By controlling surface chemistry so that every cell 'sees' the same chemical and physical environment, we can begin to assess how the distribution of cell response is affected strictly by changes in the chemistry of the cell culture surface. Using the gene for green fluorescent protein linked to the gene for the promoter of the extracellular matrix protein, tenascin, we can easily probe the end product in a signaling pathway that is purported to be linked to surface protein chemistry and to cell shape. Cell response to well-controlled, well-characterized, and highly reproducible surfaces prepared using soft lithography techniques are compared with more conventional ways of preparing extracellular matrix proteins for cell culture. Using fluorescence microscopy and image analysis of populations of cells on these surfaces, we probe quantitatively the relationship between surface chemistry, cell shape and variations in gene expression endpoint.

  1. Finite element analysis of surface modes in phononic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Guo, Yuning; Schubert, Martin; Dekorsy, Thomas

    2016-03-01

    The study of surface modes in phononic crystal waveguides in the hypersonic regime is a burgeoning field with a large number of possible applications. By using the finite element method, the band structure and the corresponding transmission spectrum of surface acoustic waves in phononic crystal waveguides generated by line defects in a silicon pillar-substrate system were calculated and investigated. The bandgaps are caused by the hybridization effect of band branches induced by local resonances and propagating modes in the substrate. By changing the sizes of selected pillars in the phononic crystal waveguides, the corresponding bands shift and localized modes emerge due to the local resonance effect induced by the pillars. This effect offers further possibilities for tailoring the propagation and filtering of elastic waves. The presented results have implications for the engineering of phonon dynamics in phononic nanostructures.

  2. Bacterial Cell Surface Adsorption of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.

    2015-12-01

    Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.

  3. Surface faceting and elemental diffusion behaviour at atomic scale for alloy nanoparticles during in situ annealing

    DOE PAGESBeta

    Chi, Miaofang; Wang, Chao; Lei, Yinkai; Wang, Guofeng; Li, Dongguo; More, Karren L.; Lupini, Andrew; Allard, Lawrence F.; Markovic, Nenad M.; Stamenkovic, Vojislav R.

    2015-11-18

    The catalytic performance of nanoparticles is primarily determined by the precise nature of the surface and near-surface atomic configurations, which can be tailored by post-synthesis annealing effectively and straightforwardly. Understanding the complete dynamic response of surface structure and chemistry to thermal treatments at the atomic scale is imperative for the rational design of catalyst nanoparticles. Here, by tracking the same individual Pt3Co nanoparticles during in situ annealing in a scanning transmission electron microscope, we directly discern five distinct stages of surface elemental rearrangements in Pt3Co nanoparticles at the atomic scale: initial random (alloy) elemental distribution; surface platinum-skin-layer formation; nucleation ofmore » structurally ordered domains; ordered framework development and, finally, initiation of amorphization. Furthermore, a comprehensive interplay among phase evolution, surface faceting and elemental inter-diffusion is revealed, and supported by atomistic simulations. Furthermore, this work may pave the way towards designing catalysts through post-synthesis annealing for optimized catalytic performance.« less

  4. Response Surface Modeling Using Multivariate Orthogonal Functions

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.; DeLoach, Richard

    2001-01-01

    A nonlinear modeling technique was used to characterize response surfaces for non-dimensional longitudinal aerodynamic force and moment coefficients, based on wind tunnel data from a commercial jet transport model. Data were collected using two experimental procedures - one based on modem design of experiments (MDOE), and one using a classical one factor at a time (OFAT) approach. The nonlinear modeling technique used multivariate orthogonal functions generated from the independent variable data as modeling functions in a least squares context to characterize the response surfaces. Model terms were selected automatically using a prediction error metric. Prediction error bounds computed from the modeling data alone were found to be- a good measure of actual prediction error for prediction points within the inference space. Root-mean-square model fit error and prediction error were less than 4 percent of the mean response value in all cases. Efficacy and prediction performance of the response surface models identified from both MDOE and OFAT experiments were investigated.

  5. Elements of a national emergency response system for nuclear accidents

    SciTech Connect

    Dickerson, M.H.

    1987-02-10

    The purpose of this paper is to suggest elements for a general emergency response system, employed at a national level, to detect, evaluate and assess the consequences of a radiological atmospheric release occurring within or outside of national boundaries. These elements are focused on the total aspect of emergency response ranging from providing an initial alarm to a total assessment of the environmental and health effects. Elements of the emergency response system are described in such a way that existing resources can be directly applied if appropriate; if not, newly developed or an expansion of existing resources can be employed. The major thrust of this paper is toward a philosophical discussion and general description of resources that would be required to implementation. If the major features of this proposal system are judged desirable for implementation, then the next level of detail can be added. The philosophy underlying this paper is preparedness - preparedness through planning, awareness and the application of technology. More specifically, it is establishment of reasonable guidelines including the definition of reference and protective action levels for public exposure to accidents involving nuclear material; education of the public, government officials and the news media; and the application of models and measurements coupled to computer systems to address a series of questions related to emergency planning, response and assessment. It is the role of a proven national emergency response system to provide reliable, quality-controlled information to decision makers for the management of environmental crises.

  6. Simulation of surface mine hydrology with the finite element storm hydrograph model

    SciTech Connect

    Smolen, M.D.; Younos, T.M.

    1980-12-01

    Use of a spatially responsive finite element model is demonstrated for simulating the hydrologic response of a reclaimed mountaintop removal operation near Beckley, West Virginia. The use of the Finite Element Storm Hydrograph Model (FESHM), developed at Virginia Tech, provides a means of incorporating spatially distributed characteristics of the watershed, thus preserving the natural configuration of overland and channel flow. The research consisted of a series of calibration studies using runoff plot data to estimate values for model parameters and reclaimed mine surface. The model verification consisted of a comparison of simulated and observed runoff characteristics using an ungaged concept. The model was found to predict runoff volume with acceptable accuracy. Peak runoff rate was generally under predicted. Poor performance of the model was noted for long duration, low intensity storm events. Use of the model to evaluate the effect of cover management for modification of hydrologic response was demonstrated.

  7. Boundary element analysis of sound scattered by a moving surface

    NASA Astrophysics Data System (ADS)

    Myers, M. K.; Hausmann, J. S.

    1990-10-01

    A solution for the acoustic field scattered from a uniformly moving rigid body in the presence of a harmonic incident source has been obtained using a boundary integral method. A derivation of the Kirchhoff formula given by Farassat and Myers (1988) for moving surfaces forms the basis for the analysis, and the development of a boundary integral method for the solution of scattering problems from moving rigid bodies is described. Finite elements are used in conjunction with the Galerkin method in order to solve the integral equation that results from the Kirchhoff formula when the observer point is placed on the moving body surface. Once appropriate surface field values are known they are inserted back into the formula in order to predict the field scattered off the body. Tests, including the so called superposition method, are carried out in order to validate the technique and to establish some confidence in its accuracy. Application of the superposition method to moving bodies is presented, and results of the two approaches are discussed. Sample calculations of scattering from a simple body are presented to illustrate the effects of variations in relevant parameters.

  8. Thermal expansion compensator having an elastic conductive element bonded to two facing surfaces

    NASA Technical Reports Server (NTRS)

    Determan, William (Inventor); Matejczyk, Daniel Edward (Inventor)

    2012-01-01

    A thermal expansion compensator is provided and includes a first electrode structure having a first surface, a second electrode structure having a second surface facing the first surface and an elastic element bonded to the first and second surfaces and including a conductive element by which the first and second electrode structures electrically and/or thermally communicate, the conductive element having a length that is not substantially longer than a distance between the first and second surfaces.

  9. Dynamic bioactive stimuli-responsive polymeric surfaces

    NASA Astrophysics Data System (ADS)

    Pearson, Heather Marie

    This dissertation focuses on the design, synthesis, and development of antimicrobial and anticoagulant surfaces of polyethylene (PE), polypropylene (PP), and poly(tetrafluoroethylene) (PTFE) polymers. Aliphatic polymeric surfaces of PE and PP polymers functionalized using click chemistry reactions by the attachment of --COOH groups via microwave plasma reactions followed by functionalization with alkyne moieties. Azide containing ampicillin (AMP) was synthesized and subsequently clicked into the alkyne prepared PE and PP surfaces. Compared to non-functionalized PP and PE surfaces, the AMP clicked surfaces exhibited substantially enhanced antimicrobial activity against Staphylococcus aureus bacteria. To expand the biocompatibility of polymeric surface anticoagulant attributes, PE and PTFE surfaces were functionalized with pH-responsive poly(2-vinyl pyridine) (P2VP) and poly(acrylic acid) (PAA) polyelectrolyte tethers terminated with NH2 and COOH groups. The goal of these studies was to develop switchable stimuli-responsive polymeric surfaces that interact with biological environments and display simultaneous antimicrobial and anticoagulant properties. Antimicrobial AMP was covalently attached to --COOH terminal ends of protected PAA, while anticoagulant heparin (HEP) was attached to terminal --NH2 groups of P2VP. When pH < 2.3, the P2VP segments are protonated and extend, but for pH > 5.5, they collapse while the PAA segments extend. Such surfaces, when exposed to Staphylococcus aureus, inhibit bacterial growth due to the presence of AMP, as well as are effective anticoagulants due to the presence of covalently attached HEP. Comparison of these "dynamic" pH responsive surfaces with "static" surfaces terminated with AMP entities show significant enhancement of longevity and surface activity against microbial film formation. The last portion of this dissertation focuses on the covalent attachment of living T1 and Φ11 bacteriophages (phages) on PE and PTFE surface

  10. Elemental mapping of planetary surfaces using gamma-ray spectroscopy

    SciTech Connect

    Reedy, R.C.

    1990-01-01

    The gamma rays escaping from a planet can be used to map the concentrations of various elements in its surface. In a planet, the high-energy particles in the galactic cosmic rays induce a cascade of particles that includes many neutrons. The {gamma} rays are made by the nuclear excitations induced by these cosmic-ray particles and their secondaries (especially capture or inelastic-scattering reactions induced by neutrons) and decay of the naturally-occurring radioelements. After a short history of planetary {gamma}-ray spectroscopy and its applications, the {gamma}-ray spectrometer planned for the Mars Observer mission is presented. The results of laboratory experiments that simulate the cosmic-ray bombardments of planetary surfaces or measure cross sections for the production of {gamma} rays and the status of the theoretical calculations for the processes that make and transport neutrons and {gamma} rays will be reviewed. The emphasis here is on studies of Mars and on new ideas, concepts, and problems that have arisen over the last decade, such as Doppler broadening and peaks from neutron scattering with germanium nuclei in a high-resolution {gamma}-ray spectrometer. 31 refs., 1 fig., 1 tab.

  11. Response of removable epoxy foam exposed to fire using an element death model.

    SciTech Connect

    Hobbs, Michael L.

    2004-09-01

    Response of removable epoxy foam (REF) to high heat fluxes is described using a decomposition chemistry model [1] in conjunction with a finite element heat conduction code [2] that supports chemical kinetics and dynamic radiation enclosures. The chemistry model [1] describes the temporal transformation of virgin foam into carbonaceous residue by considering breakdown of the foam polymer structure, desorption of gases not associated with the foam polymer, mass transport of decomposition products from the reaction site to the bulk gas, and phase equilibrium. The finite element foam response model considers the spatial behavior of the foam by using measured and predicted thermophysical properties in combination with the decomposition chemistry model. Foam elements are removed from the computational domain when the condensed mass fractions of the foam elements are close to zero. Element removal, referred to as element death, creates a space within the metal confinement causing radiation to be the dominant mode of heat transfer between the surface of the remaining foam elements and the interior walls of the confining metal skin. Predictions were compared to front locations extrapolated from radiographs of foam cylinders enclosed in metal containers that were heated with quartz lamps [3,4]. The effects of the maximum temperature of the metal container, density of the foam, the foam orientation, venting of the decomposition products, pressurization of the metal container, and the presence or absence of embedded components are discussed.

  12. Timescales of Land Surface Evapotranspiration Response

    NASA Technical Reports Server (NTRS)

    Scott, Russell; Entekhabi, Dara; Koster, Randal; Suarez, Max

    1997-01-01

    Soil and vegetation exert strong control over the evapotranspiration rate, which couples the land surface water and energy balances. A method is presented to quantify the timescale of this surface control using daily general circulation model (GCM) simulation values of evapotranspiration and precipitation. By equating the time history of evaporation efficiency (ratio of actual to potential evapotranspiration) to the convolution of precipitation and a unit kernel (temporal weighting function), response functions are generated that can be used to characterize the timescales of evapotranspiration response for the land surface model (LSM) component of GCMS. The technique is applied to the output of two multiyear simulations of a GCM, one using a Surface-Vegetation-Atmosphere-Transfer (SVAT) scheme and the other a Bucket LSM. The derived response functions show that the Bucket LSM's response is significantly slower than that of the SVAT across the globe. The analysis also shows how the timescales of interception reservoir evaporation, bare soil evaporation, and vegetation transpiration differ within the SVAT LSM.

  13. Electrically Responsive Surfaces: Experimental and Theoretical Investigations

    PubMed Central

    2016-01-01

    Conspectus Stimuli-responsive surfaces have sparked considerable interest in recent years, especially in view of their biomimetic nature and widespread biomedical applications. Significant efforts are continuously being directed at developing functional surfaces exhibiting specific property changes triggered by variations in electrical potential, temperature, pH and concentration, irradiation with light, or exposure to a magnetic field. In this respect, electrical stimulus offers several attractive features, including a high level of spatial and temporal controllability, rapid and reverse inducement, and noninvasiveness. In this Account, we discuss how surfaces can be designed and methodologies developed to produce electrically switchable systems, based on research by our groups. We aim to provide fundamental mechanistic and structural features of these dynamic systems, while highlighting their capabilities and potential applications. We begin by briefly describing the current state-of-the-art in integrating electroactive species on surfaces to control the immobilization of diverse biological entities. This premise leads us to portray our electrically switchable surfaces, capable of controlling nonspecific and specific biological interactions by exploiting molecular motions of surface-bound electroswitchable molecules. We demonstrate that our self-assembled monolayer-based electrically switchable surfaces can modulate the interactions of surfaces with proteins, mammalian and bacterial cells. We emphasize how these systems are ubiquitous in both switching biomolecular interactions in highly complex biological conditions while still offering antifouling properties. We also introduce how novel characterization techniques, such as surface sensitive vibrational sum-frequency generation (SFG) spectroscopy, can be used for probing the electrically switchable molecular surfaces in situ. SFG spectroscopy is a technique that not only allowed determining the structural

  14. Spectral response of multi-element silicon detectors

    SciTech Connect

    Ludewigt, B.A.; Rossington, C.S.; Chapman, K.

    1997-04-01

    Multi-element silicon strip detectors, in conjunction with integrated circuit pulse-processing electronics, offer an attractive alternative to conventional lithium-drifted silicon Si(Li) and high purity germanium detectors (HPGe) for high count rate, low noise synchrotron x-ray fluorescence applications. One of the major differences between the segmented Si detectors and the commercially available single-element Si(Li) or HPGe detectors is that hundreds of elements can be fabricated on a single Si substrate using standard silicon processing technologies. The segmentation of the detector substrate into many small elements results in very low noise performance at or near, room temperature, and the count rate of the detector is increased many-fold due to the multiplication in the total number of detectors. Traditionally, a single channel of detector with electronics can handle {approximately}100 kHz count rates while maintaining good energy resolution; the segmented detectors can operate at greater than MHz count rates merely due to the multiplication in the number of channels. One of the most critical aspects in the development of the segmented detectors is characterizing the charge sharing and charge loss that occur between the individual detector strips, and determining how these affect the spectral response of the detectors.

  15. Trace elements in surface sediments of Navarino Bay, Greece

    SciTech Connect

    Varnavas, S.P. ); Panagos, A.G.; Laios, G. )

    1987-01-01

    The distribution of a number of trace elements in the Navarino Bay surface sediments is examined and their source and association with the major phases is determined. Cobalt follows Al in its distribution, having its highest values towards the center and deeper parts of the bay; Zn and Cu have their highest values at the effluent outfalls of a distillery and an olive oil and olive kernel factory being decreased away. The highest concentration of Ni is found near the town Pylos, while the highest concentrations of Rb and Y are observed at the mouths of rivers Yalovas and Xerias. Organic matter has its highest content at the port of Pylos, while no significant variations have been observed in the distribution of Sn and Ga. It is demonstrated that there is an anthropogenic input of Zn, Cu, and Corg in the bay. Zn and Cu are discharged by a distillery and an olive oil and olive kernel factory, at Yalova. Organic matter is mainly derived from domestic sewage. Ni enters the bay from its southern coasts and might be derived from weathering of bauxite deposits present in the adjacent limestones. Rb and Y are transported by the rivers Yalovas and Xerias from the northeastern adjacent land area: Ni, Co, and Cu show positive correlation with Al, suggesting their incorporation in clay minerals, while Rb show positive correlation with Si, suggesting its incorporation is silicate detrital minerals. The following areas in the bay are considered to be heavily polluted: (1) the port and a large zone near Pylos (domestic sewage); (2) the port and a small area near Yalova (domestic sewage and industrial effluents); and (3) the eastern coast of the island Sphaktiria (oil). The domestic sewage pollution in Navarino Bay is of the same level as that in other Greek bays.

  16. A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor

    PubMed Central

    EL Gowini, Mohamed M.; Moussa, Walied A.

    2010-01-01

    Hydrogen plays a significant role in various industrial applications, but careful handling and continuous monitoring are crucial since it is explosive when mixed with air. Surface Acoustic Wave (SAW) sensors provide desirable characteristics for hydrogen detection due to their small size, low fabrication cost, ease of integration and high sensitivity. In this paper a finite element model of a Surface Acoustic Wave sensor is developed using ANSYS12© and tested for hydrogen detection. The sensor consists of a YZ-lithium niobate substrate with interdigital electrodes (IDT) patterned on the surface. A thin palladium (Pd) film is added on the surface of the sensor due to its high affinity for hydrogen. With increased hydrogen absorption the palladium hydride structure undergoes a phase change due to the formation of the β-phase, which deteriorates the crystal structure. Therefore with increasing hydrogen concentration the stiffness and the density are significantly reduced. The values of the modulus of elasticity and the density at different hydrogen concentrations in palladium are utilized in the finite element model to determine the corresponding SAW sensor response. Results indicate that with increasing the hydrogen concentration the wave velocity decreases and the attenuation of the wave is reduced. PMID:22205865

  17. Role of Estrogen Response Element in the Human Prolactin Gene: Transcriptional Response and Timing

    PubMed Central

    McNamara, Anne V.; Adamson, Antony D.; Dunham, Lee S. S.; Semprini, Sabrina; Spiller, David G.; McNeilly, Alan S.; Mullins, John J.

    2016-01-01

    The use of bacterial artificial chromosome (BAC) reporter constructs in molecular physiology enables the inclusion of large sections of flanking DNA, likely to contain regulatory elements and enhancers regions that contribute to the transcriptional output of a gene. Using BAC recombineering, we have manipulated a 160-kb human prolactin luciferase (hPRL-Luc) BAC construct and mutated the previously defined proximal estrogen response element (ERE) located −1189 bp relative to the transcription start site, to assess its involvement in the estrogen responsiveness of the entire hPRL locus. We found that GH3 cell lines stably expressing Luc under control of the ERE-mutated hPRL promoter (ERE-Mut) displayed a dramatically reduced transcriptional response to 17β-estradiol (E2) treatment compared with cells expressing Luc from the wild-type (WT) ERE hPRL-Luc promoter (ERE-WT). The −1189 ERE controls not only the response to E2 treatment but also the acute transcriptional response to TNFα, which was abolished in ERE-Mut cells. ERE-WT cells displayed a biphasic transcriptional response after TNFα treatment, the acute phase of which was blocked after treatment with the estrogen receptor antagonist 4-hydroxy-tamoxifen. Unexpectedly, we show the oscillatory characteristics of hPRL promoter activity in individual living cells were unaffected by disruption of this crucial response element, real-time bioluminescence imaging showed that transcription cycles were maintained, with similar cycle lengths, in ERE-WT and ERE-Mut cells. These data suggest the −1189 ERE is the dominant response element involved in the hPRL transcriptional response to both E2 and TNFα and, crucially, that cycles of hPRL promoter activity are independent of estrogen receptor binding. PMID:26691151

  18. Thioureas as reporting elements for metal-responsive fluorescent chemosensors.

    PubMed

    Vonlanthen, Mireille; Finney, Nathaniel S

    2013-04-19

    Proof that sulfur is a viable reporting element for the development of fluorescent chemosensors for metal ions is presented. To date, the majority of metal-responsive fluorescent chemosensors have relied on metal-nitrogen coordination to provide a fluorescence response, most commonly by suppressing photoinduced electron transfer (PET) quenching. While chemosensors with direct application to biology, medicine, and analytical chemistry have been so developed, reliance on the coordination chemistry of nitrogen remains a practical and conceptual limitation. Building on the fact that thioureas can quench fluorescence emission by PET, it is shown that the quenched emission of thiourea-appended naphthalimides can be restored by metal binding and that metal affinity and selectivity can be controlled through structural modification of the thiourea substituents. Further, such chemosensors can function in aqueous media and, unlike nitrogen-based chemosensors, are unresponsive to increases in [H(+)]. Given that the coordination properties of sulfur are distinct from those of nitrogen, this work lays the foundation for the development of a new class of interesting and useful metal-responsive fluorescent probes. PMID:23470031

  19. Bioadhesion to model thermally responsive surfaces

    NASA Astrophysics Data System (ADS)

    Andrzejewski, Brett Paul

    This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG 6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The gold substrates were imaged prior to SAM formation with atomic force micrscopy (AFM). Average surface roughness of the gold substrate was 0.44 nm, 0.67 nm, 1.65 nm for 15, 25 and 60 nm gold thickness, respectively. The height of the mixed SAM was measured by ellipsometry and varied from 13 to 28°A depending on surface mole fraction of C11EG6OH. The surface mole fraction of C11EG6OH for the mixed SAM was determined by X-ray photoelectron spectroscopy (XPS) with optimal thermal responsive behavior in the range of 0.4 to 0.6. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28°C and ˜55° at 40°C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal responsive of the mixed SAM are discussed. Lastly, rat fibroblasts were grown on the mixed SAM and imaged by phase contrast microscopy to show inhibition of attachment at temperatures below the molecular transition. Qualitative and quantitative measurements of the fibroblast adhesion data are provided that support the hypothesis of the mixed SAM exhibits a dominantly non-fouling molecular conformation at 25°C whereas it exhibits a dominantly fouling molecular conformation at 40°C. The adhesion of six model proteins: bovine serum albumin, collagen, pyruvate kinase, cholera toxin subunit B, ribonuclease, and lysozyme to the model thermally responsive mixed SAM were examined using AFM. All six proteins possessed adhesion to the pure component alkyl thiol, in

  20. Radiation Heat Transfer Between Diffuse-Gray Surfaces Using Higher Order Finite Elements

    NASA Technical Reports Server (NTRS)

    Gould, Dana C.

    2000-01-01

    This paper presents recent work on developing methods for analyzing radiation heat transfer between diffuse-gray surfaces using p-version finite elements. The work was motivated by a thermal analysis of a High Speed Civil Transport (HSCT) wing structure which showed the importance of radiation heat transfer throughout the structure. The analysis also showed that refining the finite element mesh to accurately capture the temperature distribution on the internal structure led to very large meshes with unacceptably long execution times. Traditional methods for calculating surface-to-surface radiation are based on assumptions that are not appropriate for p-version finite elements. Two methods for determining internal radiation heat transfer are developed for one and two-dimensional p-version finite elements. In the first method, higher-order elements are divided into a number of sub-elements. Traditional methods are used to determine radiation heat flux along each sub-element and then mapped back to the parent element. In the second method, the radiation heat transfer equations are numerically integrated over the higher-order element. Comparisons with analytical solutions show that the integration scheme is generally more accurate than the sub-element method. Comparison to results from traditional finite elements shows that significant reduction in the number of elements in the mesh is possible using higher-order (p-version) finite elements.

  1. Effects of surface removal on rolling-element fatigue

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1987-01-01

    The Lundberg-Palmgren equation was modified to show the effect on rolling-element fatigue life of removing by grinding a portion of the stressed volume of the raceways of a rolling-element bearing. Results of this analysis show that depending on the amount of material removed, and depending on the initial running time of the bearing when material removal occurs, the 10-percent life of the reground bearings ranges from 74 to 100 percent of the 10-percent life of a brand new bearing. Three bearing types were selected for testing. A total of 250 bearings were reground. Of this matter, 30 bearings from each type were endurance tested to 1600 hr. No bearing failure occurred related to material removal. Two bearing failures occurred due to defective rolling elements and were typical of those which may occur in new bearings.

  2. Finite-element approximation of electromagnetic diffraction by arbitrarily shaped surfaces

    NASA Astrophysics Data System (ADS)

    Bendali, A.; Clair, D.; Tourneur, J.

    1982-07-01

    A general finite-element method is applied to compute the skin current of a perfectly conducting surface illuminated by an incident electromagnetic wave. Surface charges over any element and currents flowing through any edge are approximated by polynomials of degree m. Some radiation patterns of two horns are calculated and compared with those obtained from experiment.

  3. Adaptive Impedance Analysis of Grooved Surface using the Finite Element Method

    SciTech Connect

    Wang, L; /SLAC

    2007-07-06

    Grooved surface is proposed to reduce the secondary emission yield in a dipole and wiggler magnet of International Linear Collider. An analysis of the impedance of the grooved surface based on adaptive finite element is presented in this paper. The performance of the adaptive algorithms, based on an element-element h refinement technique, is assessed. The features of the refinement indicators, adaptation criteria and error estimation parameters are discussed.

  4. Equivalent Dynamic Stiffness Mapping technique for identifying nonlinear structural elements from frequency response functions

    NASA Astrophysics Data System (ADS)

    Wang, X.; Zheng, G. T.

    2016-02-01

    A simple and general Equivalent Dynamic Stiffness Mapping technique is proposed for identifying the parameters or the mathematical model of a nonlinear structural element with steady-state primary harmonic frequency response functions (FRFs). The Equivalent Dynamic Stiffness is defined as the complex ratio between the internal force and the displacement response of unknown element. Obtained with the test data of responses' frequencies and amplitudes, the real and imaginary part of Equivalent Dynamic Stiffness are plotted as discrete points in a three dimensional space over the displacement amplitude and the frequency, which are called the real and the imaginary Equivalent Dynamic Stiffness map, respectively. These points will form a repeatable surface as the Equivalent Dynamic stiffness is only a function of the corresponding data as derived in the paper. The mathematical model of the unknown element can then be obtained by surface-fitting these points with special functions selected by priori knowledge of the nonlinear type or with ordinary polynomials if the type of nonlinearity is not pre-known. An important merit of this technique is its capability of dealing with strong nonlinearities owning complicated frequency response behaviors such as jumps and breaks in resonance curves. In addition, this technique could also greatly simplify the test procedure. Besides there is no need to pre-identify the underlying linear parameters, the method uses the measured data of excitation forces and responses without requiring a strict control of the excitation force during the test. The proposed technique is demonstrated and validated with four classical single-degree-of-freedom (SDOF) numerical examples and one experimental example. An application of this technique for identification of nonlinearity from multiple-degree-of-freedom (MDOF) systems is also illustrated.

  5. Diffraction of Rayleigh wave by simple surface irregularity using boundary element method

    NASA Astrophysics Data System (ADS)

    Eslami Haghighat, Abbas

    2015-06-01

    The topographic amplification effect is studied in this paper in the case of a semi-circular canyon under incident Rayleigh wave. Time-frequency domain boundary element method has been applied to investigate the wave diffraction phenomena. The model consists of a semi-circular canyon cut from an isotropic elastic half plane. The total response is decomposed into free field motion and scattered wave field. The former can be constructed analytically by superposing on incident and reflected Rayleigh waves in the half plane and the later by using boundary element method with linear elements. The analyses are performed in the frequency domain and then converted into time domain using fast Fourier transform (FFT) algorithm. It is shown that the weak and strong singularities in the governing integral equations for linear elements can be removed by analytical approaches. Different ranges of Rayleigh wavelengths from low to high are considered. The results are presented versus dimensionless frequency and distance. A limiting value for Rayleigh wavelength can be recognized beyond which the canyon has no important effects on scattering of harmonic incident waves. Furthermore, a parametric study has been performed for different values of Poisson’s ratios. The published works in the effects of this parameter are somewhat few and limited to specific values of Poisson’s ratio. Finally, the spatial variations of surface displacements for the Rayleigh wave impulse of Ricker wavelet type are obtained. The spatial distribution shows the generation of backward-scattered Rayleigh wave which its intensity depends on predominant frequency of the input impulse as well as Poisson’s ratio of the medium. Dynamic responses of the points just located at the edges of the semi-circular canyon are compared to each other which accounts for the isolation efficiency of the canyon.

  6. A genomic screen for activators of the antioxidant response element

    PubMed Central

    Liu, Yanxia; Kern, Jonathan T.; Walker, John R.; Johnson, Jeffrey A.; Schultz, Peter G.; Luesch, Hendrik

    2007-01-01

    The antioxidant response element (ARE) is a cis-acting regulatory enhancer element found in the 5′ flanking region of many phase II detoxification enzymes. Up-regulation of ARE-dependent target genes is known to have neuroprotective effects; yet, the mechanism of activation is largely unknown. By screening an arrayed collection of ≈15,000 full-length expression cDNAs in the human neuroblastoma cell line IMR-32 with an ARE-luciferase reporter, we have identified several cDNAs not previously associated with ARE activation. A subset of cDNAs, encoding sequestosome 1 (SQSTM1) and dipeptidylpeptidase 3 (DPP3), activated the ARE in primary mouse-derived cortical neurons. Overexpression of SQSTM1 and DPP3 in IMR-32 cells stimulated NF-E2-related factor 2 (NRF2) nuclear translocation and led to increased levels of NAD(P)H:quinone oxidoreductase 1, a protein which is transcriptionally regulated by the ARE. When transfected into IMR-32 neuroblastoma cells that were depleted of transcription factor NRF2 by RNA interference, SQSTM1 and DPP3 were unable to activate the ARE or induce NAD(P)H:quinone oxidoreductase 1 expression, indicating that the ARE activation upon ectopic expression of these cDNAs is mediated by NRF2. Studies with pharmacological inhibitors indicated that 1-phosphatidylinositol 3-kinase and protein kinase C signaling are essential for activity. Overexpression of these cDNAs conferred partial resistance to hydrogen peroxide or rotenone-induced toxicity, consistent with the induction of antioxidant and phase II detoxification enzymes, which can protect from oxidative stress. This work and other such studies may provide mechanisms for activating the ARE in the absence of general oxidative stress and a yet-unexploited therapeutic approach to degenerative diseases and aging. PMID:17360324

  7. Verification of Advective Bar Elements Implemented in the Aria Thermal Response Code.

    SciTech Connect

    Mills, Brantley

    2016-01-01

    A verification effort was undertaken to evaluate the implementation of the new advective bar capability in the Aria thermal response code. Several approaches to the verification process were taken : a mesh refinement study to demonstrate solution convergence in the fluid and the solid, visually examining the mapping of the advective bar element nodes to the surrounding surfaces, and a comparison of solutions produced using the advective bars for simple geometries with solutions from commercial CFD software . The mesh refinement study has shown solution convergence for simple pipe flow in both temperature and velocity . Guidelines were provided to achieve appropriate meshes between the advective bar elements and the surrounding volume. Simulations of pipe flow using advective bars elements in Aria have been compared to simulations using the commercial CFD software ANSYS Fluent (r) and provided comparable solutions in temperature and velocity supporting proper implementation of the new capability. Verification of Advective Bar Elements iv Acknowledgements A special thanks goes to Dean Dobranich for his guidance and expertise through all stages of this effort . His advice and feedback was instrumental to its completion. Thanks also goes to Sam Subia and Tolu Okusanya for helping to plan many of the verification activities performed in this document. Thank you to Sam, Justin Lamb and Victor Brunini for their assistance in resolving issues encountered with running the advective bar element model. Finally, thanks goes to Dean, Sam, and Adam Hetzler for reviewing the document and providing very valuable comments.

  8. Trace element proxies for surface ocean conditions: A synthesis of culture calibrations with planktic foraminifera

    NASA Astrophysics Data System (ADS)

    Allen, Katherine A.; Hönisch, Bärbel; Eggins, Stephen M.; Haynes, Laura L.; Rosenthal, Yair; Yu, Jimin

    2016-11-01

    The trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions. We have assembled the results of culture experiments for three species of symbiont-bearing planktic foraminifera, Globigerinoides ruber, Globigerinoides sacculifer, and Orbulina universa, and one symbiont-barren species, Globigerina bulloides, to evaluate their responses to temperature, salinity, pH, carbonate ion, and dissolved inorganic carbon (DIC) growth conditions. Trace element ratios (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Mn/Ca, Cd/Ca, Ba/Ca, Na/Ca, and U/Ca) were measured simultaneously on samples grown with the same culture techniques, which provides robust, relatable calibrations that may be used together in multi-proxy paleoceanographic studies. Our data confirm that temperature is the dominant control on foraminiferal Mg/Ca under the ranges of conditions studied and that the potential effects of salinity and CO32- on Mg/Ca of these tropical species across late Pleistocene glacial cycles are relatively small. Carbonate system experiments suggest that Sr/Ca may be useful for reconstructing large DIC changes. Na/Ca increases with salinity in G. ruber (pink), but not in G. sacculifer. As these emerging proxy relationships become more firmly established, the synthesis of multiple trace element ratios may help paleoceanographers isolate the effects of different environmental parameters in paleo records. Calcification rates (μg/day) vary among species and do not respond consistently to any experimental parameter. Comparison of our calcification rates with those observed in inorganic calcite precipitation experiments suggest that foraminifera calcify ∼100× more slowly than inorganic calcites grown in similar solutions. We suggest that calcification rate does not typically exert a dominant control on trace element partitioning in planktic foraminiferal calcite, though it may play a role for some elements under certain circumstances

  9. Surface subsidence prediction by nonlinear finite-element analysis

    SciTech Connect

    Najjar, Y. . Dept. of Civil Engineering); Zaman, M. . School of Civil Engineering and Environmental Science)

    1993-11-01

    An improved two-dimensional plane-strain numerical procedure based on the incremental-iterative nonlinear finite-element is developed to predict ground subsidence caused by underground mining. The procedure emphasizes the use of the following features: (1) an appropriate constitutive model that can accurately describe the nonlinear behavior of geological strata; and (2) an accurate algorithm for simulation of excavation sequences consistent with the actual underground mining process. The computer code is used to analyze a collapse that occurred in the Blue Goose Lease [number sign]1 Mine in northeastern Oklahoma. A parametric study is conducted to investigate the effects of some selected factors on the shape and extent of subsidence profiles. Analyses of the numerical results indicate that the nonlinear finite-element technique can be employed to meaningfully predict and characterize the potential for ground subsidence due to underground mining.

  10. Buckling of reconstruction elements of the edges of triple steps on vicinal Si(111) surfaces

    SciTech Connect

    Zhachuk, R. A.; Coutinho, J.; Rayson, M. J.; Briddon, P. R.

    2015-04-15

    The structure of steps with a height of three (111) interplanar distances on vicinal Si(111) surfaces has been analyzed through density functional theory calculations. It has been shown that several stable atomic configurations are possible depending on the buckling of the reconstruction elements of edges of the steps on the surface. It has been found that the direction of the buckling of reconstruction elements in the ground state of the surface is determined by the Coulomb interaction with their nearest atomic environment.

  11. Two-Dimensional Finite Element Ablative Thermal Response Analysis of an Arcjet Stagnation Test

    NASA Technical Reports Server (NTRS)

    Dec, John A.; Laub, Bernard; Braun, Robert D.

    2011-01-01

    The finite element ablation and thermal response (FEAtR, hence forth called FEAR) design and analysis program simulates the one, two, or three-dimensional ablation, internal heat conduction, thermal decomposition, and pyrolysis gas flow of thermal protection system materials. As part of a code validation study, two-dimensional axisymmetric results from FEAR are compared to thermal response data obtained from an arc-jet stagnation test in this paper. The results from FEAR are also compared to the two-dimensional axisymmetric computations from the two-dimensional implicit thermal response and ablation program under the same arcjet conditions. The ablating material being used in this arcjet test is phenolic impregnated carbon ablator with an LI-2200 insulator as backup material. The test is performed at the NASA, Ames Research Center Interaction Heating Facility. Spatially distributed computational fluid dynamics solutions for the flow field around the test article are used for the surface boundary conditions.

  12. Vibration Response of Multi Storey Building Using Finite Element Modelling

    NASA Astrophysics Data System (ADS)

    Chik, T. N. T.; Zakaria, M. F.; Remali, M. A.; Yusoff, N. A.

    2016-07-01

    Interaction between building, type of foundation and the geotechnical parameter of ground may trigger a significant effect on the building. In general, stiffer foundations resulted in higher natural frequencies of the building-soil system and higher input frequencies are often associated with other ground. Usually, vibrations transmitted to the buildings by ground borne are often noticeable and can be felt. It might affect the building and become worse if the vibration level is not controlled. UTHM building is prone to the ground borne vibration due to closed distance from the main road, and the construction activities adjacent to the buildings. This paper investigates the natural frequency and vibration mode of multi storey office building with the presence of foundation system and comparison between both systems. Finite element modelling (FEM) package software of LUSAS is used to perform the vibration analysis of the building. The building is modelled based on the original plan with the foundation system on the structure model. The FEM results indicated that the structure which modelled with rigid base have high natural frequency compare to the structure with foundation system. These maybe due to soil structure interaction and also the damping of the system which related to the amount of energy dissipated through the foundation soil. Thus, this paper suggested that modelling with soil is necessary to demonstrate the soil influence towards vibration response to the structure.

  13. Mapping polycomb response elements at the Drosophilla melanogaster giant locus.

    PubMed

    Abed, Jumana AlHaj; Cheng, Connie L; Crowell, Chase R; Madigan, Laura L; Onwuegbuchu, Erica; Desai, Siddhi; Benes, Judith; Jones, Richard S

    2013-12-01

    Polycomb-group (PcG) proteins are highly conserved epigenetic transcriptional regulators. They are capable of either maintaining the transcriptional silence of target genes through many cell cycles or enabling a dynamic regulation of gene expression in stem cells. In Drosophila melanogaster, recruitment of PcG proteins to targets requires the presence of at least one polycomb response element (PRE). Although the sequence requirements for PREs are not well-defined, the presence of Pho, a PRE-binding PcG protein, is a very good PRE indicator. In this study, we identify two PRE-containing regions at the PcG target gene, giant, one at the promoter, and another approximately 6 kb upstream. PRE-containing fragments, which coincide with localized presence of Pho in chromatin immunoprecipitations, were shown to maintain restricted expression of a lacZ reporter gene in embryos and to cause pairing-sensitive silencing of the mini-white gene in eyes. Our results also reinforce previous observations that although PRE maintenance and pairing-sensitive silencing activities are closely linked, the sequence requirements for these functions are not identical. PMID:24170735

  14. Nanoscale surface structuring during ion bombardment of elemental semiconductors

    NASA Astrophysics Data System (ADS)

    Anzenberg, Eitan

    2013-01-01

    Nano-patterning of surfaces with uniform ion bombardment yields a rich phase-space of topographic patterns. Particle irradiation can cause surface ultra-smoothing or self-organized nanoscale pattern formation in surface topography. Topographic pattern formation has previously been attributed to the effects of the removal of target atoms by sputter erosion. In this thesis, the surface morphology evolution of Si(100) and Ge(100) during low energy ion bombardment of Ar+ and Kr+ ions, respectively, is studied. Our facilities for studies of surface processes at the National Synchrotron Light Source (NSLS) allow in-situ characterization of surface morphology evolution during ion bombardment using grazing incidence small angle x-ray scattering (GISAXS). This technique is used to measure in reciprocal space the kinetics of formation or decay of correlated nanostructures on the surface, effectively measuring the height-height correlations. A linear model is used to characterize the early time kinetic behavior during ion bombardment as a function of ion beam incidence angle. The curvature coefficients predicted by the widely used erosive model of Bradley and Harper are quantitatively negligible and of the wrong sign when compared to the observed effect in both Si and Ge. A mass-redistribution model explains the observed ultra-smoothing at low angles, exhibits an instability at higher angles, and predicts the observed 45° critical angle separating these two regimes in Si. The Ge surface evolution during Kr+ irradiation is qualitatively similar to that observed for Ar+ irradiation of Si at the same ion energy. However, the critical angle for Ge cannot be quantitatively reproduced by the simple mass redistribution model. Crater function theory, as developed by Norris et al., incorporates both mass redistributive and erosive effects, and predicts constraining relationships between curvature coefficients. These constraints are compared to experimental data of both Si and Ge

  15. Response Predicting LTCC Firing Shrinkage: A Response Surface Analysis Study

    SciTech Connect

    Girardi, Michael; Barner, Gregg; Lopez, Cristie; Duncan, Brent; Zawicki, Larry

    2009-02-25

    The Low Temperature Cofired Ceramic (LTCC) technology is used in a variety of applications including military/space electronics, wireless communication, MEMS, medical and automotive electronics. The use of LTCC is growing due to the low cost of investment, short development time, good electrical and mechanical properties, high reliability, and flexibility in design integration (3 dimensional (3D) microstructures with cavities are possible)). The dimensional accuracy of the resulting x/y shrinkage of LTCC substrates is responsible for component assembly problems with the tolerance effect that increases in relation to the substrate size. Response Surface Analysis was used to predict product shrinkage based on specific process inputs (metal loading, layer count, lamination pressure, and tape thickness) with the ultimate goal to optimize manufacturing outputs (NC files, stencils, and screens) in achieving the final product design the first time. Three (3) regression models were developed for the DuPont 951 tape system with DuPont 5734 gold metallization based on green tape thickness.

  16. An adaptive response surface method for crashworthiness optimization

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Yang, Ren-Jye; Zhu, Ping

    2013-11-01

    Response surface-based design optimization has been commonly used for optimizing large-scale design problems in the automotive industry. However, most response surface models are built by a limited number of design points without considering data uncertainty. In addition, the selection of a response surface in the literature is often arbitrary. This article uses a Bayesian metric to systematically select the best available response surface among several candidates in a library while considering data uncertainty. An adaptive, efficient response surface strategy, which minimizes the number of computationally intensive simulations, was developed for design optimization of large-scale complex problems. This methodology was demonstrated by a crashworthiness optimization example.

  17. Relationship between tree bark surface temperature and selected meteorological elements

    NASA Astrophysics Data System (ADS)

    Středa, Tomáš; Litschmann, Tomáš; Středová, Hana

    2015-12-01

    The results were obtained by measurements in 2014 and 2015 in an apple orchard in Starý Lískovec and Těšetice (South Moravia, Czech Republic, Central Europe) into fertile planting of apple trees. The results show that the bark surface temperature during the year slightly differs from the surrounding air temperature. In addition, it is in average a few tenths of a °C higher in the period before the onset of the vegetation and several tenths of a degree lower during vegetation. Causes of these differences appear to be associated with the flow of sap as well as with foliage. Although it can be reasonably assumed that the temperature of the bark surface on the south side will be significantly affected by the global radiation, our measurements did not demonstrate this dependency. It appears that the wind speed had significantly larger influence on the temperature differences in the non-vegetation period as at speeds over 3.5 m s-1, the drop of temperature is so significant that the bark surface is colder than the surrounding air. Comparison of the development of sums of daily and hourly effective temperatures above 10 °C has shown that where daily values do not show significant differences, hourly values differed so prominently that the calculated date of emergence of adult codling moth in the bark surface was approximately one week earlier than with the use of data for air temperatures.

  18. Algorithms for Accurate and Fast Plotting of Contour Surfaces in 3D Using Hexahedral Elements

    NASA Astrophysics Data System (ADS)

    Singh, Chandan; Saini, Jaswinder Singh

    2016-07-01

    In the present study, Fast and accurate algorithms for the generation of contour surfaces in 3D are described using hexahedral elements which are popular in finite element analysis. The contour surfaces are described in the form of groups of boundaries of contour segments and their interior points are derived using the contour equation. The locations of contour boundaries and the interior points on contour surfaces are as accurate as the interpolation results obtained by hexahedral elements and thus there are no discrepancies between the analysis and visualization results.

  19. Autonomous Aerobraking Using Thermal Response Surface Analysis

    NASA Technical Reports Server (NTRS)

    Prince, Jill L.; Dec, John A.; Tolson, Robert H.

    2007-01-01

    Aerobraking is a proven method of significantly increasing the science payload that can be placed into low Mars orbits when compared to an all propulsive capture. However, the aerobraking phase is long and has mission cost and risk implications. The main cost benefit is that aerobraking permits the use of a smaller and cheaper launch vehicle, but additional operational costs are incurred during the long aerobraking phase. Risk is increased due to the repeated thermal loading of spacecraft components and the multiple attitude and propulsive maneuvers required for successful aerobraking. Both the cost and risk burdens can be significantly reduced by automating the aerobraking operations phase. All of the previous Mars orbiter missions that have utilized aerobraking have increasingly relied on onboard calculations during aerobraking. Even though the temperature of spacecraft components has been the limiting factor, operational methods have relied on using a surrogate variable for mission control. This paper describes several methods, based directly on spacecraft component maximum temperature, for autonomously predicting the subsequent aerobraking orbits and prescribing apoapsis propulsive maneuvers to maintain the spacecraft within specified temperature limits. Specifically, this paper describes the use of thermal response surface analysis in predicting the temperature of the spacecraft components and the corresponding uncertainty in this temperature prediction.

  20. Surface faceting and elemental diffusion behaviour at atomic scale for alloy nanoparticles during in situ annealing

    SciTech Connect

    Chi, Miaofang; Wang, Chao; Lei, Yinkai; Wang, Guofeng; Li, Dongguo; More, Karren L.; Lupini, Andrew; Allard, Lawrence F.; Markovic, Nenad M.; Stamenkovic, Vojislav R.

    2015-11-18

    The catalytic performance of nanoparticles is primarily determined by the precise nature of the surface and near-surface atomic configurations, which can be tailored by post-synthesis annealing effectively and straightforwardly. Understanding the complete dynamic response of surface structure and chemistry to thermal treatments at the atomic scale is imperative for the rational design of catalyst nanoparticles. Here, by tracking the same individual Pt3Co nanoparticles during in situ annealing in a scanning transmission electron microscope, we directly discern five distinct stages of surface elemental rearrangements in Pt3Co nanoparticles at the atomic scale: initial random (alloy) elemental distribution; surface platinum-skin-layer formation; nucleation of structurally ordered domains; ordered framework development and, finally, initiation of amorphization. Furthermore, a comprehensive interplay among phase evolution, surface faceting and elemental inter-diffusion is revealed, and supported by atomistic simulations. Furthermore, this work may pave the way towards designing catalysts through post-synthesis annealing for optimized catalytic performance.

  1. Numerical values of the surface free energies of solid chemical elements

    NASA Astrophysics Data System (ADS)

    Mezey, L. Z.; Giber, J.

    1984-10-01

    The applicability of a 'standard table' of values of surface free energies (or enthalpies) obtained by the CCSS (complex calculation of surface segregation) method is demonstrated by comparing calculated surface-free-energy values with several recently published experimental results. The investigation (encompassing temperatures from 1023 to 2075 K) shows that a simplified variation of the second step of CCSS is applicable in the calculation of the surface free energies of polycrystalline solid elements for any temperature of interest.

  2. Aspheric and diffractive surfaces in one, two and three element lenses

    NASA Astrophysics Data System (ADS)

    Schaub, Michael Patrick

    The use of surfaces other than spheres in optical systems has become increasingly practical due to advances in manufacturing technology. Two such alternate surface types are aspheres and diffractives. Aspheric surfaces are typically used to control the Seidel (and higher order) aberrations. Diffractive surfaces, because of their high dispersion, can be used in broadband systems to provide chromatic aberration correction as well. The aim of this work is to develop general statements about the application of aspheric and diffractive surfaces to photographic and digital imaging lenses. The use of such complex surfaces can reduce the number of elements in an imaging system while maintaining equivalent image quality. General rules regarding this design tradeoff are developed. The improvement in performance achieved by adding aspheric and diffractive surfaces, alone or in combination, to one, two and three element lenses is examined. A measure of performance is defined based upon the transverse ray errors calculated from real ray tracing. Using this, lenses of equal performance are designed for various combinations of numerical aperture and field angle. Contours of equal performance are compared for lenses of different constructional parameters. As an example application of the use of aspheric and diffractive surfaces, the design of an objective lens for a digital still camera is considered. Possible configurations for one, two and three element lenses are discussed. The use of diffractive surfaces in broadband imaging systems brings with it the associated cost of stray light due to the variation of diffraction efficiency with wavelength. Under the condition of a low contrast object, the effect of diffraction efficiency is included in the measure of performance and the systems containing diffractive surface reevaluated. The single axis symmetry of the aspheric or diffractive surfaces used results in the inability to remove surface to surface decenter in the lens element

  3. Frequency Modulated Translocational Oscillations of Nrf2 Mediate the Antioxidant Response Element Cytoprotective Transcriptional Response

    PubMed Central

    Xue, Mingzhan; Momiji, Hiroshi; Rabbani, Naila; Barker, Guy; Bretschneider, Till; Shmygol, Anatoly; Rand, David A.

    2015-01-01

    Abstract Aims: Stress responsive signaling coordinated by nuclear factor erythroid 2-related factor 2 (Nrf2) provides an adaptive response for protection of cells against toxic insults, oxidative stress and metabolic dysfunction. Nrf2 regulates a battery of protective genes by binding to regulatory antioxidant response elements (AREs). The aim of this study was to examine how Nrf2 signals cell stress status and regulates transcription to maintain homeostasis. Results: In live cell microscopy we observed that Nrf2 undergoes autonomous translocational frequency-modulated oscillations between cytoplasm and nucleus. Oscillations occurred in quiescence and when cells were stimulated at physiological levels of activators, they decrease in period and amplitude and then evoke a cytoprotective transcriptional response. We propose a mechanism whereby oscillations are produced by negative feedback involving successive de-phosphorylation and phosphorylation steps. Nrf2 was inactivated in the nucleus and reactivated on return to the cytoplasm. Increased frequency of Nrf2 on return to the cytoplasm with increased reactivation or refresh-rate under stress conditions activated the transcriptional response mediating cytoprotective effects. The serine/threonine-protein phosphatase PGAM5, member of the Nrf2 interactome, was a key regulatory component. Innovation: We found that Nrf2 is activated in cells without change in total cellular Nrf2 protein concentration. Regulation of ARE-linked protective gene transcription occurs rather through translocational oscillations of Nrf2. We discovered cytoplasmic refresh rate of Nrf2 is important in maintaining and regulating the transcriptional response and links stress challenge to increased cytoplasmic surveillance. We found silencing and inhibition of PGAM5 provides potent activation of Nrf2. Conclusion: Frequency modulated translocational oscillations of Nrf2 mediate the ARE-linked cytoprotective transcriptional response. Antioxid. Redox

  4. A direct evidence of vibrationally delocalized response at ice surface

    SciTech Connect

    Ishiyama, Tatsuya; Morita, Akihiro

    2014-11-14

    Surface-specific vibrational spectroscopic responses at isotope diluted ice and amorphous ice are investigated by molecular dynamics (MD) simulations combined with quantum mechanics/molecular mechanics calculations. The intense response specific to the ordinary crystal ice surface is predicted to be significantly suppressed in the isotopically diluted and amorphous ices, demonstrating the vibrational delocalization at the ordinary ice surface. The collective vibration at the ice surface is also analyzed with varying temperature by the MD simulation.

  5. Application of Goubau Surface Wave Transmission Line for Improved Bench Testing of Diagnostic Beamline Elements

    SciTech Connect

    John Musson, Keith Cole, Sheldon Rubin

    2009-05-01

    In-air test fixtures for beamline elements typically utilize an X-Y positioning stage, and a wire antenna excited by an RF source. In most cases, the antenna contains a standing wave, and is useful only for coarse alignment measurements in CW mode. A surface-wave (SW) based transmission line permits RF energy to be launched on the wire, travel through the beamline component, and then be absorbed in a load. Since SW transmission lines employ travelling waves, the RF energy can be made to resemble the electron beam, limited only by ohmic losses and dispersion. Although lossy coaxial systems are also a consideration, the diameter of the coax introduces large uncertainties in centroid location. A SW wire is easily constructed out of 200 micron magnet wire, which more accurately approximates the physical profile of the electron beam. Benefits of this test fixture include accurate field mapping, absolute calibration for given beam currents, Z-axis independence, and temporal response measurements of sub-nanosecond pulse structures. Descriptions of the surface wave launching technique, transmission line, and instrumentation are presented, along with measurement data.

  6. Electrochemical machining process for forming surface roughness elements on a gas turbine shroud

    DOEpatents

    Lee, Ching-Pang; Johnson, Robert Alan; Wei, Bin; Wang, Hsin-Pang

    2002-01-01

    The back side recessed cooling surface of a shroud defining in part the hot gas path of a turbine is electrochemically machined to provide surface roughness elements and spaces therebetween to increase the heat transfer coefficient. To accomplish this, an electrode with insulating dielectric portions and non-insulating portions is disposed in opposition to the cooling surface. By passing an electrolyte between the cooling surface and electrode and applying an electrical current between the electrode and a shroud, roughness elements and spaces therebetween are formed in the cooling surface in opposition to the insulating and non-insulating portions of the electrode, hence increasing the surface area and heat transfer coefficient of the shroud.

  7. Comparison of Response Surface and Kriging Models for Multidisciplinary Design Optimization

    NASA Technical Reports Server (NTRS)

    Simpson, Timothy W.; Korte, John J.; Mauery, Timothy M.; Mistree, Farrokh

    1998-01-01

    In this paper, we compare and contrast the use of second-order response surface models and kriging models for approximating non-random, deterministic computer analyses. After reviewing the response surface method for constructing polynomial approximations, kriging is presented as an alternative approximation method for the design and analysis of computer experiments. Both methods are applied to the multidisciplinary design of an aerospike nozzle which consists of a computational fluid dynamics model and a finite-element model. Error analysis of the response surface and kriging models is performed along with a graphical comparison of the approximations, and four optimization problems m formulated and solved using both sets of approximation models. The second-order response surface models and kriging models-using a constant underlying global model and a Gaussian correlation function-yield comparable results.

  8. Comparison of Response Surface and Kriging Models in the Multidisciplinary Design of an Aerospike Nozzle

    NASA Technical Reports Server (NTRS)

    Simpson, Timothy W.

    1998-01-01

    The use of response surface models and kriging models are compared for approximating non-random, deterministic computer analyses. After discussing the traditional response surface approach for constructing polynomial models for approximation, kriging is presented as an alternative statistical-based approximation method for the design and analysis of computer experiments. Both approximation methods are applied to the multidisciplinary design and analysis of an aerospike nozzle which consists of a computational fluid dynamics model and a finite element analysis model. Error analysis of the response surface and kriging models is performed along with a graphical comparison of the approximations. Four optimization problems are formulated and solved using both approximation models. While neither approximation technique consistently outperforms the other in this example, the kriging models using only a constant for the underlying global model and a Gaussian correlation function perform as well as the second order polynomial response surface models.

  9. Assessment of crown-of-thorns skeletal elements in surface sediment of the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Henderson, R. A.

    1992-07-01

    A total of 1655 crown-of-thorns starfish skeletal elements were recovered from 237 surface sediment samples from Davies, Centipede, Myrmidon, Hope, Holbourne Island, 22 110, Gannet Cay and Lady Musgrave Island Reefs of the central and southern sectors of the Great Barrier Reef. Three categories of reef may be recognised on the incidence of Acanthaster planci skeletal elements in surface sediment from these and previously studied reefs: category A (abundant, >12 elements kg1-), category C (common, 3 8 elements kg-1) and category C (rare, 0 0.1 elements kg-1). These categories parallel estimates of crown-of-thorns populations in the period 1986 1990. “A” reefs have generally experienced high intensity outbreaks, “C” reefs less intense or perhaps less frequent outbreaks and “R” reefs have had little or no crown-of-thorns presence. The incidence of crown-of-thorns skeletal elements in surface sediment potentially provides an indication of population densities and outbreaks over a time scale of several decades. A perspective of contemporary crown-of-thorns incidence on the many reefs of the GBR lacking direct observational records may thereby be obtained. For Holbourne Island a comparison was made of element incidence in an area of known mass mortality induced by poisoning with a control area that was undisturbed. The incidence of A. planci skeletal elements is comparable in the two areas and similar to the incidence established for other reefs such as Green Island and John Brewer where high intensity outbreaks are known to have occurred. A direct relationship between high incidence of elements in surface sediment and mass mortality following outbreak events is indicated.

  10. Research on machining error compensation in high-precision surface grinding machine for optical aspheric elements

    NASA Astrophysics Data System (ADS)

    Ke, Xiaolong; Guo, Yinbiao; Zhang, Shihan; Huang, Hao

    2010-10-01

    Using aspheric component in optical system can correct optical aberration, acquire high imaging quality, improve the optical characteristic, simplify system structure, and reduce system volume. Nowadays, high-precision surface grinding machine is an important approach to processing optical aspheric elements. However, because of the characteristics of optical aspheric elements, the processing method makes a higher demand to whole performance of surface grinding machine, and hardly to achieve ideal machining effect. Taking high generality and efficiency into account, this paper presents a compensation method for machining errors of high-precision surface grinding machine, which bases on optical aspheric elements, to achieve high-precision machining for all kinds of optical aspheric elements. After compensation, the machining accuracy of grinding machine could reach 2um/200×200mm. The research bases on NC surface grinding machine which is self developed. First of all, this paper introduces machining principle for optical aspheric elements on the grinding machine. And then error sources which producing errors are analyzed. By contacting and non-contacting measurement sensors, measurement software which is self designed realizes on-position measure for grinded workpiece, then fits surface precision and machining errors. Through compensation software for machining error which is self designed, compensation algorithm is designed and translated compensation data into G-code for the high-precision grinding machine to achieve compensation machining. Finally, by comparison between machining error compensation before and after processing, the experiments for this purpose are done to validate the compensation machining accuracy.

  11. Finite-element impact response of debonded composite turbine blades

    NASA Astrophysics Data System (ADS)

    Dey, Sudip; Karmakar, Amit

    2014-02-01

    This paper investigates on the transient behavior of debonded composite pretwisted rotating shallow conical shells which could be idealized as turbine blades subjected to low velocity normal impact using finite-element method. Lagrange's equation of motion is used to derive the dynamic equilibrium equation and the moderate rotational speeds are considered neglecting the Coriolis effect. An eight-noded isoparametric plate bending element is employed in the finite element formulation incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the impact parameters. The time-dependent equations are solved by using Newmark's time integration scheme. Parametric studies are performed to investigate the effects of triggering parameters like angle of twist, rotational speed, laminate configuration and location of debonding considering low velocity normal impact at the center of eight-layered graphite-epoxy composite cantilevered conical shells with bending stiff ([0o2/{±} 30o]s), torsion stiff ([45°/-45°/-45°/45°]s) and cross-ply ([0°/90°/0°/90°]s) laminate configurations.

  12. Population responses to contour integration: early encoding of discrete elements and late perceptual grouping.

    PubMed

    Gilad, Ariel; Meirovithz, Elhanan; Slovin, Hamutal

    2013-04-24

    The neuronal mechanisms underlying perceptual grouping of discrete, similarly oriented elements are not well understood. To investigate this, we measured neural population responses using voltage-sensitive dye imaging in V1 of monkeys trained on a contour-detection task. By mapping the contour and background elements onto V1, we could study their neural processing. Population response early in time showed activation patches corresponding to the contour/background individual elements. However, late increased activity in the contour elements, along with suppressed activity in the background elements, enabled us to visualize in single trials a salient continuous contour "popping out" from a suppressed background. This modulated activity in the contour and in background extended beyond the cortical representation of individual contour or background elements. Finally, the late modulation was correlated with behavioral performance of contour saliency and the monkeys' perceptual report. Thus, opposing responses in the contour and background may underlie perceptual grouping in V1.

  13. Tuning a fuzzy controller using quadratic response surfaces

    NASA Technical Reports Server (NTRS)

    Schott, Brian; Whalen, Thomas

    1992-01-01

    Response surface methodology, an alternative method to traditional tuning of a fuzzy controller, is described. An example based on a simulated inverted pendulum 'plant' shows that with (only) 15 trial runs, the controller can be calibrated using a quadratic form to approximate the response surface.

  14. Surface geometric analysis of anatomic structures using biquintic finite element interpolation.

    PubMed

    Smith, D B; Sacks, M S; Vorp, D A; Thornton, M

    2000-06-01

    The surface geometry of anatomic structures can have a direct impact upon their mechanical behavior in health and disease. Thus, mechanical analysis requires the accurate quantification of three-dimensional in vivo surface geometry. We present a fully generalized surface fitting method for surface geometric analysis that uses finite element based hermite biquintic polynomial interpolation functions. The method generates a contiguous surface of C2 continuity, allowing computation of the finite strain and curvature tensors over the entire surface with respect to a single in-surface coordinate system. The Sobolev norm, which restricts element length and curvature, was utilized to stabilize the interpolating polynomial at boundaries and in regions of sparse data. A major advantage of the current method is its ability to fully quantify surface deformation from an unstructured grid of data points using a single interpolation scheme. The method was validated by computing both the principal curvature distributions for phantoms of known curvatures and the principal stretch and principal change of curvature distributions for a synthetic spherical patch warping into an ellipsoidal shape. To demonstrate the applicability to biomedical problems, the method was applied to quantify surface curvatures of an abdominal aortic aneurysm and the principal strains and change of curvatures of a deforming bioprosthetic heart valve leaflet. The method proved accurate for the computation of surface curvatures, as well as for strains and curvature change for a surface undergoing large deformations. PMID:10983706

  15. Trace element concentration in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India.

    PubMed

    Kasilingam, K; Suresh Gandhi, M; Krishnakumar, S; Magesh, N S

    2016-10-15

    The present work was carried to decipher the trace element accumulation in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India. The elemental concentration and correlation results suggest that fine fractions with CaCO3 content followed by organic matter (OM) of the surface sediments control the trace element accumulation in the study area. In addition, Fe and Mn concentration is chiefly contributed from riverine process and controlled by the mangrove ecosystem. The other elements are derived into marine environment through confluence of untreated industrial pollutants into the river system. The EF result shows that the studied marine sediments are enriched by Ni, Mn, Cu, Pb, Cd, Cr, followed by Zn. The order of the pollution intensity with respect to geo-accumulation index suggests the following ascending order: Ni>Mn>Fe>Cu>Pb>Cd>Cr>Zn. Pollution Load Index (PLI) values reveal that all the samples are falling under moderately to unpolluted category. PMID:27325606

  16. Trace element concentration in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India.

    PubMed

    Kasilingam, K; Suresh Gandhi, M; Krishnakumar, S; Magesh, N S

    2016-10-15

    The present work was carried to decipher the trace element accumulation in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India. The elemental concentration and correlation results suggest that fine fractions with CaCO3 content followed by organic matter (OM) of the surface sediments control the trace element accumulation in the study area. In addition, Fe and Mn concentration is chiefly contributed from riverine process and controlled by the mangrove ecosystem. The other elements are derived into marine environment through confluence of untreated industrial pollutants into the river system. The EF result shows that the studied marine sediments are enriched by Ni, Mn, Cu, Pb, Cd, Cr, followed by Zn. The order of the pollution intensity with respect to geo-accumulation index suggests the following ascending order: Ni>Mn>Fe>Cu>Pb>Cd>Cr>Zn. Pollution Load Index (PLI) values reveal that all the samples are falling under moderately to unpolluted category.

  17. Oxide formation and alloying elements enrichment on TRIP steel surface during inter-critical annealing.

    PubMed

    Gong, Y F; Birosca, S; Kim, H S; De Cooman, B C

    2008-06-01

    The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steels. The alloying element enrichments and the oxide morphology on transformation-induced plasticity steel surfaces are strongly influenced by the dew point of the furnace atmosphere and annealing temperature. The formation of a thin oxide film and enrichment of the alloying elements during annealing may result in surface defects on galvanized sheet products. The present contribution reports on the use of microanalysis techniques such as electron backscatter diffraction, glow discharge optical emission spectroscopy and electron probe micro-analysis for the detailed surface analysis of inter-critically annealed transformation-induced plasticity steel such as oxide phase determination, microstructure and microtexture evolutions.

  18. The relation of stream sediment surface area, grain size and composition to trace element chemistry

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.

    1987-01-01

    Intensive studies of 17 geographically and hydrologically diverse stream bed sediments provide information on the relation between grain size, surface area, and operationally defined geochemical phases (e.g. Mn oxides, amorphous Fe oxides) to trace element concentrations. Of the size fractions investigated ( 125 ??m), each of the various phases contribute to overall sample surface area. For material having mean grain sizes in the very fine sand range and finer (<125 ??m), the same phases act as surface-area inhibitors by cementing fine grains together to form aggregates. This increases the mean grain size of the sample and reduces the surface area. The presence of these aggregates may explain why the <63 ??m or <125 ??m size fractions are more important to sediment-trace element levels and surface area than other finer fractions. ?? 1987.

  19. Elemental Analyses of Hanford Surface Neutron Moisture Measurement Calibration Standard Samples

    SciTech Connect

    Watson, W.T., Westinghouse Hanford

    1996-07-31

    Elemental analyses have been performed on twenty samples taken from the moisture standards prepared to use in performing experimental calibrations of the surface neutron moisture measurement system. These standards consisted of mixtures of sand, hydrated alumina, and boron carbide. Elemental analyses were performed primarily to discover the quantities of any strong thermal neutron absorbers that may have been present in the mixture in unknown trace quantities.

  20. Selective detection of elemental mercury vapor using a surface acoustic wave (SAW) sensor.

    PubMed

    Kabir, K M Mohibul; Sabri, Ylias M; Matthews, Glenn I; Jones, Lathe A; Ippolito, Samuel J; Bhargava, Suresh K

    2015-08-21

    The detection of elemental mercury (Hg(0)) within industrial processes is extremely important as it is the first major step in ensuring the efficient operation of implemented mercury removal technologies. In this study, a 131 MHz surface acoustic wave (SAW) delay line sensor with gold electrodes was tested towards Hg(0) vapor (24 to 365 ppbv) with/without the presence of ammonia (NH3) and humidity (H2O), as well as volatile organic compounds (VOCs) such as acetaldehyde (MeCHO), ethylmercaptan (EM), dimethyl disulfide (DMDS) and methyl ethyl ketone (MEK), which are all common interfering gas species that co-exist in many industrial applications requiring mercury monitoring. The developed sensor exhibited a detection limit of 0.7 ppbv and 4.85 ppbv at 35 and 55 °C, respectively. Furthermore, a repeatability of 97% and selectivity of 92% in the presence of contaminant gases was exhibited by the sensor at the chosen operating temperature of 55 °C. The response magnitude of the developed SAW sensor towards different concentrations of Hg(0) vapor fitted well with the Langmuir extension isotherm (otherwise known as loading ratio correlation (LRC)) which is in agreement with our basic finite element method (FEM) work where an LRC isotherm was observed for a simplified model of the SAW sensor responding to different Hg contents deposited on the Au based electrodes. Overall, the results indicate that the developed SAW sensor can be a potential solution for online selective detection of low concentrations of Hg(0) vapor found in industrial stack effluents.

  1. Acid drainage response to surface limestone layers

    SciTech Connect

    Geidel, G.; Caruccio, F.T.

    1982-12-01

    A 150 acre drainage basin in an unreclaimed coal strip mine in east-central Ohio was studied and extensively monitored to determine the effect of a surface application of limestone on the ground water quality. Prior to the limestone treatment the ground and surface water of the basin was acidic due to pyrite oxidation in the spoil. In order to assess the effect of the limestone application the basin was divided into seven sub-basins, five of which were treated and two which served as controls. The seeps from the treated sub-basins with low acid concentrations became alkaline due to neutralization but after a long dry period, they returned to their acid condition. The moderately and highly acidic seeps showed a decline in the acid concentrations which could be attributed to a combination of neutralization and a decrease in the rate of pyrite oxidation. The results of this field study and simultaneous laboratory experiments showed that under natural conditions, with no limestone application, the acidity generated by pyrite oxidation in a backfill decreased. A surface application of limestone slightly enhanced the decrease in acidity by both neutralization and decreasing the rate of pyrite oxidation. However, the limestone application did not provide sufficient alkalinity to produce either neutral or alkaline discharges from the abandoned coal strip mine site.

  2. Controlled Dissolution of Surface Layers for Elemental Analysis by Inductively Coupled Plasma-Mass Spectrometry

    SciTech Connect

    Lorge, Susan Elizabeth

    2007-01-01

    Determining the composition of thin layers is increasingly important for a variety of industrial materials such as adhesives, coatings and microelectronics. Secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), glow discharge mass spectrometry (GDMS), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are some of the techniques that are currently employed for the direct analysis of the sample surface. Although these techniques do not suffer from the contamination problems that often plague sample dissolution studies, they do require matrix matched standards for quantification. Often, these standards are not readily available. Despite the costs of clean hoods, Teflon pipette tips and bottles, and pure acids, partial sample dissolution is the primary method used in the semiconductor industry to quantify surface impurities. Specifically, vapor phase decomposition (VPD) coupled to ICP-MS or total reflection x-ray fluorescence (TXRF) provides elemental information from the top most surface layers at detection sensitivities in the 107-1010atoms/cm2 range. The ability to quantify with standard solutions is a main advantage of these techniques. Li and Houk applied a VPD-like technique to steel. The signal ratio of trace element to matrix element was used for quantification. Although controlled dissolution concentrations determined for some of the dissolved elements agreed with the certified values, concentrations determined for refractory elements (Ti, Nb and Ta) were too low. LA-ICP-MS and scanning electron microscopy (SEM) measurements indicated that carbide grains distributed throughout the matrix were high in these refractory elements. These elements dissolved at a slower rate than the matrix element, Fe. If the analyte element is not removed at a rate similar to the matrix element a true

  3. Moral Responsibility: The Missing Element in Educational Leadership

    ERIC Educational Resources Information Center

    Vasillopulos, Christopher; Denney, Morgan

    2013-01-01

    We intend to deepen the understanding of leadership in general and educational leadership in particular by an analysis of Chester Barnard's (1938) concept of executive responsibility. By so doing we believe that we will reveal how an educational leader can foster the environment in which competent teachers can optimize their students' learning…

  4. Three-dimensional reconstruction of surface-breaking flaws using finite element methods

    NASA Astrophysics Data System (ADS)

    Gladchtein, R. Schifini; Bruno, A. C.

    2000-05-01

    We present an iterative algorithm that reconstructs the geometry of three-dimensional surface-breaking flaws from measurements using an NDE magnetic flux leakage technique. Several surface-breaking flaws in a ferromagnetic sample have been modeled using the finite element method and later reconstructed by an optimization routine. This reconstruction was achieved by modifying the coordinates of several surface nodes of the finite element mesh, solving the magnetostatic problem, and optimizing it by a least-squares method. The magnetic field was measured above the surface of the sample. This inverse solution algorithm might be particularly useful to characterize flaws detected by magnetic in-line inspection tools in oil and gas pipelines.

  5. Controlled chemical modification of the internal surface of photonic crystal fibers for application as biosensitive elements

    NASA Astrophysics Data System (ADS)

    Pidenko, Sergey A.; Burmistrova, Natalia A.; Pidenko, Pavel S.; Shuvalov, Andrey A.; Chibrova, Anastasiya A.; Skibina, Yulia S.; Goryacheva, Irina Y.

    2016-10-01

    Photonic crystal fibers (PCF) are one of the most promising materials for creation of constructive elements for bio-, drug and contaminant sensing based on unique optical properties of the PCF as effective nanosized optical signal collectors. In order to provide efficient and controllable binding of biomolecules, the internal surface of glass hollow core photonic crystal fibers (HC-PCF) has been chemically modified with silanol groups and functionalized with (3-aminopropyl) triethoxysilane (APTES). The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of silanol groups on the HC-PCF inner surface. The relationship between amount of silanol groups on the HC-PCF inner surface and efficiency of following APTES functionalization has been evaluated. Covalent binding of horseradish peroxidase (chosen as a model protein) on functionalized PCF inner surface has been performed successively, thus verifying the possibility of creating a biosensitive element.

  6. Enhancing Surface Finish of Additively Manufactured Titanium and Cobalt Chrome Elements Using Laser Based Finishing

    NASA Astrophysics Data System (ADS)

    Gora, Wojciech S.; Tian, Yingtao; Cabo, Aldara Pan; Ardron, Marcus; Maier, Robert R. J.; Prangnell, Philip; Weston, Nicholas J.; Hand, Duncan P.

    Additive manufacturing (AM) offers the possibility of creating a complex free form object as a single element, which is not possible using traditional mechanical machining. Unfortunately the typically rough surface finish of additively manufactured parts is unsuitable for many applications. As a result AM parts must be post-processed; typically mechanically machined and/or and polished using either chemical or mechanical techniques (both of which have their limitations). Laser based polishing is based on remelting of a very thin surface layer and it offers potential as a highly repeatable, higher speed process capable of selective area polishing, and without any waste problems (no abrasives or liquids). In this paper an in-depth investigation of CW laser polishing of titanium and cobalt chrome AM elements is presented. The impact of different scanning strategies, laser parameters and initial surface condition on the achieved surface finish is evaluated.

  7. Mechanisms regulating osteoblast response to surface microtopography and vitamin D

    NASA Astrophysics Data System (ADS)

    Bell, Bryan Frederick, Jr.

    A comprehensive understanding of the interactions between orthopaedic and dental implant surfaces with the surrounding host tissue is essential in the design of advanced biomaterials that better promote bone growth and osseointegration of implants. Dental implants with roughened surfaces and high surface energy are well known to promote osteoblast differentiation in vitro and promote increased bone-to-implant contact in vivo. In addition, increased surface roughness increases osteoblasts response to the vitamin D metabolite 1alpha,25(OH)2D3. However, the exact mechanisms mediating cell response to surface properties and 1alpha,25(OH)2D3 are still being elucidated. The central aim of the thesis is to investigate whether integrin signaling in response to rough surface microtopography enhances osteoblast differentiation and responsiveness to 1alpha,25(OH)2D3. The hypothesis is that the integrin alpha5beta1 plays a role in osteoblast response to surface microtopography and that 1alpha,25(OH) 2D3 acts through VDR-independent pathways involving caveolae to synergistically enhance osteoblast response to surface roughness and 1alpha,25(OH) 2D3. To test this hypothesis the objectives of the studies performed in this thesis were: (1) to determine if alpha5beta 1 signaling is required for osteoblast response to surface microstructure; (2) to determine if increased responsiveness to 1alpha,25(OH)2D 3 requires the vitamin D receptor, (3) to determine if rough titanium surfaces functionalized with the peptides targeting integrins (RGD) and transmembrane proteoglycans (KRSR) will enhance both osteoblast proliferation and differentiation, and (4) to determine whether caveolae, which are associated with integrin and 1alpha,25(OH)2D3 signaling, are required for enhance osteogenic response to surface microstructure and 1alpha,25(OH)2D 3. The results demonstrate that integrins, VDR, and caveolae play important roles in mediating osteoblast response to surface properties and 1alpha,25

  8. 33 CFR Appendix D to Part 154 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Training Elements for Oil Spill... Appendix D to Part 154—Training Elements for Oil Spill Response Plans 1. General 1.1The portion of the plan... contracted oil spill removal organizations and the procedures to notify the activate such organizations....

  9. 33 CFR Appendix D to Part 154 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Training Elements for Oil Spill... Appendix D to Part 154—Training Elements for Oil Spill Response Plans 1. General 1.1The portion of the plan... contracted oil spill removal organizations and the procedures to notify the activate such organizations....

  10. 33 CFR Appendix D to Part 154 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Training Elements for Oil Spill... Appendix D to Part 154—Training Elements for Oil Spill Response Plans 1. General 1.1The portion of the plan... contracted oil spill removal organizations and the procedures to notify the activate such organizations....

  11. 33 CFR Appendix D to Part 154 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ....14Occupational Safety and Health Administration requirements for worker health and safety (29 CFR 1910.120). 3... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Training Elements for Oil Spill... Appendix D to Part 154—Training Elements for Oil Spill Response Plans 1. General 1.1The portion of the...

  12. 33 CFR Appendix C to Part 155 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... worker health and safety (29 CFR 1910.120). 3. Further Considerations In drafting the training section of... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Training Elements for Oil Spill.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General...

  13. 33 CFR Appendix D to Part 154 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ....14Occupational Safety and Health Administration requirements for worker health and safety (29 CFR 1910.120). 3... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Training Elements for Oil Spill... Appendix D to Part 154—Training Elements for Oil Spill Response Plans 1. General 1.1The portion of the...

  14. Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

    PubMed

    Ikkatai, Yuko; Watanabe, Shigeru

    2015-08-01

    Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars. PMID:26103119

  15. Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

    PubMed

    Ikkatai, Yuko; Watanabe, Shigeru

    2015-08-01

    Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

  16. The effect of roughness elements on wind erosion: The importance of surface shear stress distribution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Representation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the veg...

  17. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  18. The real-time monitoring surface figure of optical elements in continuous polishing

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Xu, Xueke; Wei, Chaoyang; Gu, Jianxun; Dun, Aihuan; Shao, Jianda

    2014-08-01

    Continuous ring polishing is the key process in large aperture optical elements. The surface figure of polishing pad is inferred by the offline testing surface figure of workpiece. The defects, low processing efficiency and uncertainty processing time in traditional continuous polishing, the real-time monitoring method of polishing is proposed. The realtime monitoring system is set up based on the computer, the dynamic interferometer, a beam expanding system and a beam reflecting system. There are a workpiece and a glass monitoring plate placing in same ring. The surface figure of workpiece, monitored by the monitoring plate, synchronize with the surface of glass monitoring plate in Peak-Valley (PV) and POWER. The new method with simple structure is fast measuring and judgmental directly to the changes of surface figures. The results of real-time monitoring and surface figure converging on the workpiece are valid for continuous polishing through experimental validation.

  19. Superficial composition in binary solid solutions A(B): Drastic effect of pure element surface tensions

    NASA Astrophysics Data System (ADS)

    Rolland, A.; Aufray, B.

    1985-10-01

    This paper deals with a comparative study of surface segragation of Pb and Ni respectively from Ag(Pb)(111) and Ag(Ni)(111) solid solutions. A high level of segregation of the solute is observed for both systems characterized by very low solute solubility. However, the superficial composition strongly depends on the relative surface tensions of the pure elements: the solute atoms are strictly on superficial sites when γ solute is smaller than γ solvent; in contrast uppermost layer consists purely of solvent when γ solute is greater than γ solvent. Two schematic distributions in close proximity to the surface are proposed in the last case.

  20. Refractive micro-optical elements for surface plasmons: from classical to gradient index optics.

    PubMed

    Devaux, Eloïse; Laluet, Jean-Yves; Stein, Benedikt; Genet, Cyriaque; Ebbesen, Thomas; Weeber, Jean-Claude; Dereux, Alain

    2010-09-27

    Controlling the propagation of surface plasmons along a metal-dielectric interface is a key feature for the development of surface plasmon based circuits. We have designed various two-dimensional refractive dielectric optical elements for surface plasmons (SP) and characterized their capacity to route SP, using near- or far-field techniques. We first present basic devices analogous to usual optical components and the associated challenges for SP optics. We then use a metamaterial approach to locally vary the refractive index and fabricate gradient index structures for SP circuitry.

  1. Numerical values of the surface free energies of solid chemical elements

    NASA Astrophysics Data System (ADS)

    Mezey, L. Z.; Giber, J.

    1984-10-01

    The knowledge of the surface free energies γ {i/o}of solid chemical elements is necessary in many practically important subjects. The description of the quantities γ {i/o}(more correctly termed as the surface free enthalpies) is a part of a new “complex calculation of surface segregation” (CCSS) method, proposed by the authors. Here the applicability of a “standard table” of the values of γ {/i o }, obtained in that part of CCSS is shown by comparing the calculated values of γ {/i o }with several recently published experimental results.

  2. Surface flaw reliability analysis of ceramic components with the SCARE finite element postprocessor program

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John P.; Nemeth, Noel N.

    1987-01-01

    The SCARE (Structural Ceramics Analysis and Reliability Evaluation) computer program on statistical fast fracture reliability analysis with quadratic elements for volume distributed imperfections is enhanced to include the use of linear finite elements and the capability of designing against concurrent surface flaw induced ceramic component failure. The SCARE code is presently coupled as a postprocessor to the MSC/NASTRAN general purpose, finite element analysis program. The improved version now includes the Weibull and Batdorf statistical failure theories for both surface and volume flaw based reliability analysis. The program uses the two-parameter Weibull fracture strength cumulative failure probability distribution model with the principle of independent action for poly-axial stress states, and Batdorf's shear-sensitive as well as shear-insensitive statistical theories. The shear-sensitive surface crack configurations include the Griffith crack and Griffith notch geometries, using the total critical coplanar strain energy release rate criterion to predict mixed-mode fracture. Weibull material parameters based on both surface and volume flaw induced fracture can also be calculated from modulus of rupture bar tests, using the least squares method with known specimen geometry and grouped fracture data. The statistical fast fracture theories for surface flaw induced failure, along with selected input and output formats and options, are summarized. An example problem to demonstrate various features of the program is included.

  3. Hormone response element binding proteins: novel regulators of vitamin D and estrogen signaling

    PubMed Central

    Lisse, Thomas S.; Hewison, Martin; Adams, John S.

    2011-01-01

    Insights from vitamin D-resistant New World primates and their human homologues as models of natural and pathological insensitivity to sterol/steroid action have uncovered a family of novel intracellular vitamin D and estrogen regulatory proteins involved in hormone action. The proteins, known as “vitamin D or estrogen response element-binding proteins”, behave as potent cis-acting, transdominant regulators to inhibit steroid receptor binding to DNA response elements and is responsible for vitamin D and estrogen resistances. This set of interactors belongs to the heterogeneous nuclear ribonucleoprotein (hnRNP) family of previously known pre-mRNA-interacting proteins. This review provides new insights into the mechanism by which these novel regulators of signaling and metabolism can act to regulate responses to vitamin D and estrogen. In addition the review also describes other molecules that are known to influence nuclear receptor signaling through interaction with hormone response elements. PMID:21236284

  4. On the surface elemental composition of non-corroded and corroded dental ceramic materials in vitro.

    PubMed

    Milleding, P; Karlsson, S; Nyborg, L

    2003-06-01

    Dental ceramics are traditionally looked upon as inert materials. As many are glass phased, it may be hypothesized that they will be subjected to glass corrosion in aqueous environments. The aim of the study was therefore to analyze the surface elemental composition of glass-phased and all-crystalline ceramics, before and after low- and high-intensity, in vitro corrosion (milli-Q-water at 37+/-2 degrees C for 18 h and 4% acetic acid at 80+/-2 degrees C for 18 h, respectively). The analysis of the surface elemental composition was performed using ESCA. The hypothesis was confirmed. After high-intensity corrosion, the complete wash out of alkali ions, alkaline-earth ions and elemental alumina was found, leaving behind a surface totally dominated by silica. The all-crystalline ceramics, densely sintered alumina and yttria-partially stabilized tetragonal zirconia, displayed only minor surface changes, even after high-intensity corrosion. In comparison to the corrosion testing in acid, the corrosion process in milli-Q-water did not produce different results in principle, except for the lower magnitude of the depletion of alkali ions and the virtually unchanged level of elemental alumina. Unexpectedly, no substantial difference in surface degradation was found between the glass ceramic and the ordinary porcelain-fused-to-metal ceramic or between ceramics of higher sintering temperature and those of low or ultra-low sintering temperature. The composition and microstructure alone did not appear to provide a full explanation for the inter-individual differences in surface corrosion when exposed to comparable environmental conditions.

  5. Full gradient stabilized cut finite element methods for surface partial differential equations

    NASA Astrophysics Data System (ADS)

    Burman, Erik; Hansbo, Peter; Larson, Mats G.; Massing, André; Zahedi, Sara

    2016-10-01

    We propose and analyze a new stabilized cut finite element method for the Laplace-Beltrami operator on a closed surface. The new stabilization term provides control of the full $\\mathbb{R}^3$ gradient on the active mesh consisting of the elements that intersect the surface. Compared to face stabilization, based on controlling the jumps in the normal gradient across faces between elements in the active mesh, the full gradient stabilization is easier to implement and does not significantly increase the number of nonzero elements in the mass and stiffness matrices. The full gradient stabilization term may be combined with a variational formulation of the Laplace-Beltrami operator based on tangential or full gradients and we present a simple and unified analysis that covers both cases. The full gradient stabilization term gives rise to a consistency error which, however, is of optimal order for piecewise linear elements, and we obtain optimal order a priori error estimates in the energy and $L^2$ norms as well as an optimal bound of the condition number. Finally, we present detailed numerical examples where we in particular study the sensitivity of the condition number and error on the stabilization parameter.

  6. A cut finite element method for coupled bulk-surface problems on time-dependent domains

    NASA Astrophysics Data System (ADS)

    Hansbo, Peter; Larson, Mats G.; Zahedi, Sara

    2016-08-01

    In this contribution we present a new computational method for coupled bulk-surface problems on time-dependent domains. The method is based on a space-time formulation using discontinuous piecewise linear elements in time and continuous piecewise linear elements in space on a fixed background mesh. The domain is represented using a piecewise linear level set function on the background mesh and a cut finite element method is used to discretize the bulk and surface problems. In the cut finite element method the bilinear forms associated with the weak formulation of the problem are directly evaluated on the bulk domain and the surface defined by the level set, essentially using the restrictions of the piecewise linear functions to the computational domain. In addition a stabilization term is added to stabilize convection as well as the resulting algebraic system that is solved in each time step. We show in numerical examples that the resulting method is accurate and stable and results in well conditioned algebraic systems independent of the position of the interface relative to the background mesh.

  7. Fabrication of large diffractive optical elements in thick film on a concave lens surface

    NASA Astrophysics Data System (ADS)

    Xie, Yongjun; Lu, Zhenwu; Li, Fengyou

    2003-05-01

    We demonstrate experimentally the technique of fabricating large diffractive optical elements (DOEs) in thick film on a concave lens surface (mirrors) with precise alignment by using the strategy of double exposure. We adopt the method of double exposure to overcome the difficulty of processing thick photoresist on a large curved substrate. A uniform thick film with arbitrary thickness on a concave lens can be obtained with this technique. We fabricate a large concentric circular grating with a 10-im period on a concave lens surface in film with a thickness of 2.0 im after development. It is believed that this technique can also be used to fabricate larger DOEs in thicker film on the concave or convex lens surface with precise alignment. There are other potential applications of this technique, such as fabrication of micro-optoelectromechanical systems (MOEMS) or microelectromechanical systems (MEMS) and fabrication of microlens arrays on a large concave lens surface or convex lens surface with precise alignment.

  8. The cycle of trace elements between surface waters and lower atmosphere

    NASA Astrophysics Data System (ADS)

    Church, T.; Amouroux, D.

    2003-04-01

    The accurate cycles of C, N or S between the surface of natural waters and the lower atmosphere is a priority being proposed by the Surface Ocean Lower Atmosphere Studies (SOLAS). This priority also provides a paradigm for analagous cycling of many volatile trace metals and metalloids (most notably Hg) with important biogeochemical processing and ecological consequences. The process of redox chemistry and alkylation is abundantly evidenced by an array of related trace elements that include As, Hg, I, Po, Sb, Se, and Sn. Atmospheric emission of volatile species of other trace elements such as Bi, Pb, Sb, and Zn can also include significant anthropogenic and natural sources from both high and low temperature emissions. Quantification of volatile metal fluxes is now possible, such as naturally from quiescent (fumurolic) volcanic process, or anthropogenically from landfill and sewage digestion practices. These elements also exhibit significant cycles with the atmosphere by virtue of documented natural alkylation to volatile species by both biotic and abiotic processes. The alkylation processes also provide for the biogeochemistry of these species once introduced to the aqueous environment. As such, these metals are introduced into the biosphere along with related global carbon cycles. Another sea to air transfer mechanism involves the concentration of trace elements in the marine surface micro layer and fractional enrichment in marine aerosols. This results in the exponential array of global enrichment factors in both aerosols and precipitation. Thus a fundamental question for SOLAS biogeochemists are ways to specify the processes this so called “global distillation” of heavier elements through the atmosphere. For example how to distinguish, or trace the importance of the sea to air transfer processes via vapor phase (gas exchange) versus surface micro-layer (aerosol generation) mechanisms should be a prime goal of SOLAS.

  9. Multi-elemental surface mapping and analysis of carbonaceous shale by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Tao; Liu, Jie; Shi, Qi; He, Yi; Niu, Guanghui; Duan, Yixiang

    2016-01-01

    Gas shale is one of the important unconventional hydrocarbon source rocks, whose composition, such as mineral components and redox sensitive trace elements, has been proved as important geochemical proxies playing essential roles in indicating the gas potential and gas productivity in recent geological researches. Fast and accurate measurements for the shale composition, especially those with spatial resolution, will reveal rich information for the understanding and evaluation of gas shale reservoirs. In this paper, we demonstrated the potentiality as well as feasibility of laser-induced breakdown spectroscopy as an effective technique to perform spectrochemical analysis for shale samples. In case of the bulk analysis of pressed shale pellet, spectral analysis of the plasma emission revealed high sensitivity of LIBS for major, minor and even trace elements. More than 356 lines emitted by 19 different elements can be found. Among these species, redox sensitive trace elements such as V, Cr, and Ni were detected with high signal-to-ratios. Two-dimensional surface micro-analysis for the concerned major or minor elements with strong emissions was then applied to the smoothed shale slab. Local thermodynamic equilibrium for the plasma was first verified with a line profile point-by-point on the sample surface, the matrix effect was then assessed as negligible by the extracted electron density and temperature of the plasmas induced at each position on the same profile. Concentration mappings for the major elements of Si, Al, Fe, Ca, Mg, Na and K were finally constructed with their measured relative variations of line emission intensities. The distribution and correlations of these elements in concentration may reflect changes of shale mineral components with respected to the variations of the depositional environments and provide an important clue in identifying sedimentary processes when combined with other geological or geochemical evidences. These results well

  10. An explicit Lagrangian finite element method for free-surface weakly compressible flows

    NASA Astrophysics Data System (ADS)

    Cremonesi, Massimiliano; Meduri, Simone; Perego, Umberto; Frangi, Attilio

    2016-07-01

    In the present work, an explicit finite element approach to the solution of the Lagrangian formulation of the Navier-Stokes equations for weakly compressible fluids or fluid-like materials is investigated. The introduction of a small amount of compressibility is shown to allow for the formulation of a fast and robust explicit solver based on a particle finite element method. Newtonian and Non-Newtonian Bingham laws are considered. A barotropic equation of state completes the model relating pressure and density fields. The approach has been validated through comparison with experimental tests and numerical simulations of free surface fluid problems involving water and water-soil mixtures.

  11. Determining Surface Plasmon Resonance Response Factors for Deposition onto Three-Dimensional Surfaces

    PubMed Central

    Roper, D. Keith

    2009-01-01

    Intrinsic sorption rates of ligand/receptor binding have been measured by surface plasmon resonance (SPR) using response factors for deposition of proteins or smaller molecules on planar surfaces. In this study generalized expressions for SPR response factor and effective refractive index are developed to measure rates of analyte sorption onto 3-D surfaces. The expressions are specialized for two limiting cases of immediate practical interest and broad applicability: analyte deposition onto a homogeneous anisotropic porous media and deposition onto close-packed solid spheres adjacent to the sensor surface. These new equations specify media capacity, characteristic size and analyte concentration that are necessary to obtain identifiable responses from interaction with anisotropic porous media or chromatographic resin. These developments are illustrated by comparing response factors for Adenovirus Type 5 on planar surfaces, porous media and adsorptive spheres. PMID:19844593

  12. An extended pressure finite element space for two-phase incompressible flows with surface tension

    NASA Astrophysics Data System (ADS)

    Groß, Sven; Reusken, Arnold

    2007-05-01

    We consider a standard model for incompressible two-phase flows in which a localized force at the interface describes the effect of surface tension. If a level set (or VOF) method is applied then the interface, which is implicitly given by the zero level of the level set function, is in general not aligned with the triangulation that is used in the discretization of the flow problem. This non-alignment causes severe difficulties w.r.t. the discretization of the localized surface tension force and the discretization of the flow variables. In cases with large surface tension forces the pressure has a large jump across the interface. In standard finite element spaces, due to the non-alignment, the functions are continuous across the interface and thus not appropriate for the approximation of the discontinuous pressure. In many simulations these effects cause large oscillations of the velocity close to the interface, so-called spurious velocities. In this paper, for a simplified model problem, we give an analysis that explains why known (standard) methods for discretization of the localized force term and for discretization of the pressure variable often yield large spurious velocities. In the paper [S. Groß, A. Reusken, Finite element discretization error analysis of a surface tension force in two-phase incompressible flows, Preprint 262, IGPM, RWTH Aachen, SIAM J. Numer. Anal. (accepted for publication)], we introduce a new and accurate method for approximation of the surface tension force. In the present paper, we use the extended finite element space (XFEM), presented in [N. Moes, J. Dolbow, T. Belytschko, A finite element method for crack growth without remeshing, Int. J. Numer. Meth. Eng. 46 (1999) 131-150; T. Belytschko, N. Moes, S. Usui, C. Parimi, Arbitrary discontinuities in finite elements, Int. J. Numer. Meth. Eng. 50 (2001) 993-1013], for the discretization of the pressure. We show that the size of spurious velocities is reduced substantially, provided we

  13. 33 CFR Appendix C to Part 155 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... worker health and safety (29 CFR 1910.120). 3. Further Considerations In drafting the training section of... Response Plans C Appendix C to Part 155 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General...

  14. Vibration response mechanism of faulty outer race rolling element bearings for quantitative analysis

    NASA Astrophysics Data System (ADS)

    Cui, Lingli; Zhang, Yu; Zhang, Feibin; Zhang, Jianyu; Lee, Seungchul

    2016-03-01

    For the quantitative fault diagnosis of rolling element bearings, a nonlinear vibration model for fault severity assessment of rolling element bearings is established in this study. The outer race defect size parameter is introduced into the dynamic model, and vibration response signals of rolling element bearings under different fault sizes are simulated. The signals are analyzed quantitatively to observe the relationship between vibration responses and fault sizes. The impact points when the ball rolls onto and away from the defect are identified from the vibration response signals. Next, the impact characteristic that reflects the fault severity in rolling element bearings is obtained from the time interval between two impact points. When the width of the bearing fault is small, the signals are presented as clear single impact. The signals gradually become double impacts with increasing size of defects. The vibration signals of a rolling element bearings test rig are measured for different outer race fault sizes. The experimental results agree well with the results from simulations. These results are useful for understanding the vibration response mechanism of rolling element bearings under various degrees of fault severity.

  15. Failure Behavior Characterization of Mo-Modified Ti Surface by Impact Test and Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Ma, Yong; Qin, Jianfeng; Zhang, Xiangyu; Lin, Naiming; Huang, Xiaobo; Tang, Bin

    2015-07-01

    Using the impact test and finite element simulation, the failure behavior of the Mo-modified layer on pure Ti was investigated. In the impact test, four loads of 100, 300, 500, and 700 N and 104 impacts were adopted. The three-dimensional residual impact dents were examined using an optical microscope (Olympus-DSX500i), indicating that the impact resistance of the Ti surface was improved. Two failure modes cohesive and wearing were elucidated by electron backscatter diffraction and energy-dispersive spectrometer performed in a field-emission scanning electron microscope. Through finite element forward analysis performed at a typical impact load of 300 N, stress-strain distributions in the Mo-modified Ti were quantitatively determined. In addition, the failure behavior of the Mo-modified layer was determined and an ideal failure model was proposed for high-load impact, based on the experimental and finite element forward analysis results.

  16. Instrument for elemental composition studies of solids on planetary surfaces with sub-ppm detection sensitivity

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

    2012-04-01

    Current space instruments prove to be successful for a global chemical mapping of the entire planetary body or to perform a local chemical analysis, helpful in determination of modal mineralogy. Nevertheless, the sensitivity and low spatial resolution of these spectroscopic instruments limit the chemical analysis to the most abundant elements with some exceptions (e.g., measurements of Th, K, and H elements by Gamma and neutron spectrometers). Furthermore, the spectroscopic analysis typically provides the chemical composition of 1 micrometer of the uppermost surface layers, which are frequently affected by space weathering effects, again, with the exception of Gamma/neutron investigation where the composition of up to 1 m thick subsurface can be measured. New and recently accepted space instruments, such as Laser Induced Breakdown (LIBS) and Laser Ablation/Ionisation Mass Spectrometers (LIMS) are thought to improve these chemical analysis providing more localised chemical sampling with higher sensitivity and accuracy. We will demonstrate the performance of a highly miniaturised laser ablation time of flight mass spectrometer designed for space research for the elemental analysis of solid materials (Rohner et al., 2003). The instrument enables mass spectrometric analysis with sub-ppm detection limits and a typical mass resolution of ~700, sufficient to detect all elements and their isotopes. The studies of NIST standards, minerals and meteoritic samples will be reviewed to emphasize its capability for quantitative analysis and chemical mapping of the inhomogeneous samples with a high spatial (vertical and lateral) resolution. LIMS measurements provide means for investigation of principal elements (metals, non-metals) and allow an analysis of trace elements distributed within a suite of soils and rocks. Thus, LIMS measurements will allow the identification of the mineralogical context of planetary surface and better understanding of the geologic/geochemical structure

  17. On the transfer of protective coating elements on a metal surface from halide gaseous media

    NASA Astrophysics Data System (ADS)

    Abraimov, N. V.

    2016-06-01

    The processes occurring during the formation of multicomponent diffusion coatings on nickel alloys at the stage of delivery of elements on the article surface when chlorine, bromine, and iodine halides are used as activators are considered. Balance equations and calculated values are given for the partial pressures in the composition of a gas phase of components participating in chemical transport reaction; the possible reactions of delivering elements on the article surfaces and the structures of Ni-Al, Ni-Cr, Ni-Cr-Al, Co-Cr-Al coatings deposited on the ZhS26, ZhS6U, ZhS32, and VZhL12U alloys are presented.

  18. Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.

    1992-01-01

    Hypervelocity impact features from very small particles (less than 3 microns in diameter) on several of the electro-active dust sensors used in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microscope. The same analytical techniques were applied to impact and containment features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on tray B12. Very little unambiguously identifiable impactor debris was found in the central craters or shatter zones of small impacts in this crystalline surface. The surface contamination, ubiquitous on the surface of the Long Duration Exposure Facility, has greatly complicated data collection and interpretation from microparticle impacts on all surfaces.

  19. Barley responses to combined waterlogging and salinity stress: separating effects of oxygen deprivation and elemental toxicity

    PubMed Central

    Zeng, Fanrong; Shabala, Lana; Zhou, Meixue; Zhang, Guoping; Shabala, Sergey

    2013-01-01

    Salinity and waterlogging are two major factors affecting crop production around the world and often occur together (e.g., salt brought to the surface by rising water tables). While the physiological and molecular mechanisms of plant responses to each of these environmental constraints are studied in detail, the mechanisms underlying plant tolerance to their combined stress are much less understood. In this study, whole-plant physiological responses to individual/combined salinity and waterlogging stresses were studied using two barley varieties grown in either vermiculite (semi-hydroponics) or sandy loam. Two weeks of combined salinity and waterlogging treatment significantly decreased plant biomass, chlorophyll content, maximal quantum efficiency of PSII and water content (WC) in both varieties, while the percentage of chlorotic and necrotic leaves and leaf sap osmolality increased. The adverse effects of the combined stresses were much stronger in the waterlogging-sensitive variety Naso Nijo. Compared with salinity stress alone, the combined stress resulted in a 2-fold increase in leaf Na+, but a 40% decrease in leaf K+ content. Importantly, the effects of the combined stress were more pronounced in sandy loam compared with vermiculite and correlated with changes in the soil redox potential and accumulation of Mn and Fe in the waterlogged soils. It is concluded that hypoxia alone is not a major factor determining differential plant growth under adverse stress conditions, and that elemental toxicities resulting from changes in soil redox potential have a major impact on genotypic differences in plant physiological and agronomical responses. These results are further discussed in the context of plant breeding for waterlogging stress tolerance. PMID:23967003

  20. Barley responses to combined waterlogging and salinity stress: separating effects of oxygen deprivation and elemental toxicity.

    PubMed

    Zeng, Fanrong; Shabala, Lana; Zhou, Meixue; Zhang, Guoping; Shabala, Sergey

    2013-01-01

    Salinity and waterlogging are two major factors affecting crop production around the world and often occur together (e.g., salt brought to the surface by rising water tables). While the physiological and molecular mechanisms of plant responses to each of these environmental constraints are studied in detail, the mechanisms underlying plant tolerance to their combined stress are much less understood. In this study, whole-plant physiological responses to individual/combined salinity and waterlogging stresses were studied using two barley varieties grown in either vermiculite (semi-hydroponics) or sandy loam. Two weeks of combined salinity and waterlogging treatment significantly decreased plant biomass, chlorophyll content, maximal quantum efficiency of PSII and water content (WC) in both varieties, while the percentage of chlorotic and necrotic leaves and leaf sap osmolality increased. The adverse effects of the combined stresses were much stronger in the waterlogging-sensitive variety Naso Nijo. Compared with salinity stress alone, the combined stress resulted in a 2-fold increase in leaf Na(+), but a 40% decrease in leaf K(+) content. Importantly, the effects of the combined stress were more pronounced in sandy loam compared with vermiculite and correlated with changes in the soil redox potential and accumulation of Mn and Fe in the waterlogged soils. It is concluded that hypoxia alone is not a major factor determining differential plant growth under adverse stress conditions, and that elemental toxicities resulting from changes in soil redox potential have a major impact on genotypic differences in plant physiological and agronomical responses. These results are further discussed in the context of plant breeding for waterlogging stress tolerance.

  1. Quantifying crustal response to deep active intrusions with geodesy-based finite element modeling

    NASA Astrophysics Data System (ADS)

    Henderson, S. T.; Pritchard, M. E.; Elliott, J.

    2013-12-01

    The Altiplano-Puna Volcanic Complex (APVC, 21-24 S, 66-69 W) is a first order feature of the Central Andes Volcanic Arc. The APVC consists of over 10,000 km^3 of dacitic ignimbrites deposited in the late Miocene, making it one of the largest concentrations of silicic volcanism in the world. The persistent and intense magmatic flux in this region has likely contributed to the thickened crust (50-70 km), elevated geotherm (>50 C/km) and extensive partial melt (<20 %) inferred under the APVC in modern times. Furthermore, satellite geodetic measurements show surface deformation centered on Uturuncu Volcano (22.27 S, 67.22 W) that is consistent with an ongoing magmatic intrusion in the middle to lower crust. The unique geologic setting and availability of multiple geophysical datasets provide an exceptional opportunity to locate fluid accumulation depths and model the resulting crustal mechanical response. InSAR data between 05/1992 and 01/2011 show that the deformation anomaly is characterized by axis-symmetric constant vertical uplift of 1-10 mm/yr over a radius of 35 km, which is surrounded by 1-4 mm/yr subsidence out to 75 km. One possible explanation for such a signal is diapiric rise of melt from the middle crust. We seek to determine if observed deformation can be alternatively explained by vertical ascent of magma from the lower (~70 km) to middle crust (~20 km). Such a model would be consistent with the short duration of deformation from geomorphic studies (less than 2200 years) and the potential abrupt cessation of uplift seen in a single continuous GPS station starting in 04/2010 near the center of deformation. We therefore test multiple finite element models that match spatial and temporal surface deformation, achieve mass balance between source and sink reservoirs, and require physically realistic rheological parameters of the crust. Modeling is performed with Pylith finite element software on a cylindrical three dimensional domain with a radius of 300 km

  2. A rigid surface boundary element for soil-structure interaction analysis in the direct time domain

    NASA Astrophysics Data System (ADS)

    Rizos, D. C.

    Many soil-structure interaction problems involve studies of single or multiple rigid bodies of arbitrary shape and soil media. The commonly used boundary element methods implement the equations of the rigid body in a form that depends on the particulars of the geometry and requires partitioning and condensation of the associated algebraic system of equations. The present work employs the direct time domain B-Spline BEM for 3D elastodynamic analysis and presents an efficient implementation of rigid bodies of arbitrary shape in contact with, or embedded in, elastic media. The formulation of a rigid surface boundary element introduced herein is suitable for direct superposition in the BEM system of algebraic equations. Consequently, solutions are computed in a single analysis step, eliminating, thus, the need for partitioning of the system of equations. Computational efficiency is also achieved due to the extremely sparse form of the associated coefficient matrices. The proposed element can be used for the modeling of single or multiple rigid bodies of arbitrary shape within the framework of the BEM method. The efficiency and general nature of the proposed element is demonstrated through applications related to the dynamic analysis of rigid surface and embedded foundations and their interaction with embedded rigid bodies of arbitrary shape.

  3. Transport and dispersion of pollutants in surface impoundments: a finite element model

    SciTech Connect

    Yeh, G.T.

    1980-07-01

    A surface impoundment model in finite element (SIMFE) is presented to enable the simulation of flow circulations and pollutant transport and dispersion in natural or artificial lakes, reservoirs or ponds with any number of islands. This surface impoundment model consists of two sub-models: hydrodynamic and pollutant transport models. Both submodels are simulated by the finite element method. While the hydrodynamic model is solved by the standard Galerkin finite element scheme, the pollutant transport model can be solved by any of the twelve optional finite element schemes built in the program. Theoretical approximations and the numerical algorithm of SIMFE are described. Detail instruction of the application are given and listing of FORTRAN IV source program are provided. Two sample problems are given. One is for an idealized system with a known solution to show the accuracy and partial validation of the models. The other is applied to Prairie Island for a set of hypothetical input data, typifying a class of problems to which SIMFE may be applied.

  4. Material selection and corresponding optimal surface relief height for multilayer diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Dun, Xiong; Jin, Weiqi; Wang, Xia

    2015-11-01

    We present a model based on refractive index difference analysis for optimization of material selection for multilayer diffractive optical elements (MLDOEs). From the proposed model, two important relationships are derived: the relationship between material selection and the maximum polychromatic integral diffraction efficiency of MLDOEs, and between material selection and the surface relief heights of MLDOEs. The new relationships are more comprehensive and reliable than those discussed in previous papers. A theoretical expression of the optimal surface relief heights of MLDOEs is also presented, and its correctness is demonstrated through a comparison with the results of enumeration optimization.

  5. Structural basis of VDR–DNA interactions on direct repeat response elements

    PubMed Central

    Shaffer, Paul L.; Gewirth, Daniel T.

    2002-01-01

    The vitamin D receptor (VDR) forms homo- or heterodimers on response elements composed of two hexameric half-sites separated by 3 bp of spacer DNA. We describe here the crystal structures at 2.7–2.8 Å resolution of the VDR DNA-binding region (DBD) in complex with response elements from three different promoters: osteopontin (SPP), canonical DR3 and osteocalcin (OC). These structures reveal the chemical basis for the increased affinity of VDR for the SPP response element, and for the poor stability of the VDR–OC complex, relative to the canonical DR3 response element. The homodimeric protein–protein interface is stabilized by van der Waals interactions and is predominantly non-polar. An extensive α-helix at the C-terminal end of the VDR DBD resembles that found in the thyroid hormone receptor (TR), and suggests a mechanism by which VDR and TR discriminate among response elements. Selective structure-based mutations in the asymmetric homodimeric interface result in a VDR DBD protein that is defective in homodimerization but now forms heterodimers with the 9-cis retinoic acid receptor (RXR) DBD. PMID:11980721

  6. Osteoblastic response to pectin nanocoating on titanium surfaces.

    PubMed

    Gurzawska, Katarzyna; Svava, Rikke; Yihua, Yu; Haugshøj, Kenneth Brian; Dirscherl, Kai; Levery, Steven B; Byg, Inge; Damager, Iben; Nielsen, Martin W; Jørgensen, Bodil; Jørgensen, Niklas Rye; Gotfredsen, Klaus

    2014-10-01

    Osseointegration of titanium implants can be improved by organic and inorganic nanocoating of the surface. The aim of our study was to evaluate the effect of organic nanocoating of titanium surface with unmodified and modified pectin Rhamnogalacturonan-Is (RG-Is) isolated from potato and apple with respect to surface properties and osteogenic response in osteoblastic cells. Nanocoatings on titanium surfaces were evaluated by scanning electron microscopy, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of coated RG-Is on cell adhesion, cell viability, bone matrix formation and mineralization was tested using SaOS-2 cells. Nanocoating with pectin RG-Is affected surface properties and in consequence changed the environment for cellular response. The cells cultured on surfaces coated with RG-Is from potato with high content of linear 1.4-linked galactose produced higher level of mineralized matrix compared with control surfaces and surfaces coated with RG-I with low content of linear 1.4-linked galactose. The study showed that the pectin RG-Is nanocoating not only changed chemical and physical titanium surface properties, but also specific coating with RG-Is containing high amount of galactan increased mineralized matrix formation of osteoblastic cells in vitro. PMID:25175196

  7. Conserved enhancer and silencer elements responsible for differential Adh transcription in Drosophila cell lines.

    PubMed Central

    Ayer, S; Benyajati, C

    1990-01-01

    The distal promoter of Adh is differentially expressed in Drosophila tissue culture cell lines. After transfection with an exogenous Adh gene, there was a specific increase in distal alcohol dehydrogenase (ADH) transcripts in ADH-expressing (ADH+) cells above the levels observed in transfected ADH-nonexpressing (ADH-) cells. We used deletion mutations and a comparative transient-expression assay to identify the cis-acting elements responsible for enhanced Adh distal transcription in ADH+ cells. DNA sequences controlling high levels of distal transcription were localized to a 15-base-pair (bp) region nearly 500 bp upstream of the distal RNA start site. In addition, a 61-bp negative cis-acting element was found upstream from and adjacent to the enhancer. When this silencer element was deleted, distal transcription increased only in the ADH+ cell line. These distant upstream elements must interact with the promoter elements, the Adf-1-binding site and the TATA box, as they only influenced transcription when at least one of these two positive distal promoter elements was present. Internal deletions targeted to the Adf-1-binding site or the TATA box reduced transcription in both cell types but did not affect the transcription initiation site. Distal transcription in transfected ADH- cells appears to be controlled primarily through these promoter elements and does not involve the upstream regulatory elements. Evolutionary conservation in distantly related Drosophila species suggests the importance of these upstream elements in correct developmental and tissue-specific expression of ADH. Images PMID:1694013

  8. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    NASA Astrophysics Data System (ADS)

    Pennisi, C. P.; Sevcencu, C.; Dolatshahi-Pirouz, A.; Foss, M.; Lundsgaard Hansen, J.; Nylandsted Larsen, A.; Zachar, V.; Besenbacher, F.; Yoshida, K.

    2009-09-01

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  9. Titanium surface hydrophilicity modulates the human macrophage inflammatory cytokine response.

    PubMed

    Alfarsi, Mohammed A; Hamlet, Stephen M; Ivanovski, Saso

    2014-01-01

    Increased titanium surface hydrophilicity has been shown to accelerate dental implant osseointegration. Macrophages are important in the early inflammatory response to surgical implant placement and influence the subsequent healing response. This study investigated the modulatory effect of a hydrophilic titanium surface on the inflammatory cytokine expression profile in a human macrophage cell line (THP-1). Genes for 84 cytokines, chemokines, and their receptors were analyzed following exposure to (1) polished (SMO), (2) micro-rough sand blasted, acid etched (SLA), and (3) hydrophilic-modified SLA (modSLA) titanium surfaces for 1 and 3 days. By day 3, the SLA surface elicited a pro-inflammatory response compared to the SMO surface with statistically significant up-regulation of 16 genes [Tumor necrosis factor (TNF) Interleukin (IL)-1β, Chemokine (C-C motif) ligand (CCL)-1, 2, 3, 4, 18, 19, and 20, Chemokine (C-X-C motif) ligand (CXCL)-1, 5, 8 and 12, Chemokine (C-C motif) receptor (CCR)-7, Lymphotoxin-beta (LTB), and Leukotriene B4 receptor (LTB4R)]. This effect was countered by the modSLA surface, which down-regulated the expression of 10 genes (TNF, IL-1α and β, CCL-1, 3, 19 and 20, CXCL-1 and 8, and IL-1 receptor type 1), while two were up-regulated (osteopontin and CCR5) compared to the SLA surface. These cytokine gene expression changes were confirmed by decreased levels of corresponding protein secretion in response to modSLA compared to SLA. These results show that a hydrophilic titanium surface can modulate human macrophage pro-inflammatory cytokine gene expression and protein secretion. An attenuated pro-inflammatory response may be an important molecular mechanism for faster and/or improved wound healing.

  10. Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis

    PubMed Central

    Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

    2016-01-01

    An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective. PMID:26762972

  11. Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis

    NASA Astrophysics Data System (ADS)

    Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

    2016-01-01

    An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective.

  12. Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis.

    PubMed

    Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

    2016-01-01

    An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective. PMID:26762972

  13. The three-dimensional elemental distribution based on the surface topography by confocal 3D-XRF analysis

    NASA Astrophysics Data System (ADS)

    Yi, Longtao; Qin, Min; Wang, Kai; Lin, Xue; Peng, Shiqi; Sun, Tianxi; Liu, Zhiguo

    2016-09-01

    Confocal three-dimensional micro-X-ray fluorescence (3D-XRF) is a good surface analysis technology widely used to analyse elements and elemental distributions. However, it has rarely been applied to analyse surface topography and 3D elemental mapping in surface morphology. In this study, a surface adaptive algorithm using the progressive approximation method was designed to obtain surface topography. A series of 3D elemental mapping analyses in surface morphology were performed in laboratories to analyse painted pottery fragments from the Majiayao Culture (3300-2900 BC). To the best of our knowledge, for the first time, sample surface topography and 3D elemental mapping were simultaneously obtained. Besides, component and depth analyses were also performed using synchrotron radiation confocal 3D-XRF and tabletop confocal 3D-XRF, respectively. The depth profiles showed that the sample has a layered structure. The 3D elemental mapping showed that the red pigment, black pigment, and pottery coat contain a large amount of Fe, Mn, and Ca, respectively. From the 3D elemental mapping analyses at different depths, a 3D rendering was obtained, clearly showing the 3D distributions of the red pigment, black pigment, and pottery coat. Compared with conventional 3D scanning, this method is time-efficient for analysing 3D elemental distributions and hence especially suitable for samples with non-flat surfaces.

  14. Geochemical baseline distribution of harmful elements in the surface soils of Campania region.

    NASA Astrophysics Data System (ADS)

    Albanese, Stefano; Lima, Annamaria; Qu, Chengkai; Cicchella, Domenico; Buccianti, Antonella; De Vivo, Benedetto

    2015-04-01

    Environmental geochemical mapping has assumed an increasing relevance and the separation of values to discriminate between anthropogenic pollution and natural (geogenic) sources has become crucial to address environmental problems affecting the quality of life of human beings. In the last decade, a number of geochemical prospecting projects, mostly focused on surface soils (topsoils), were carried out at different scales (from regional to local) across the whole Campania region (Italy) to characterize the distribution of both harmful elements and persistent organic pollutants (POP) in the environment and to generating a valuable database to serve as reference in developing geomedical studies. During the 2014, a database reporting the distribution of 53 chemical elements in 3536 topsoil samples, collected across the whole region, was completed. The geochemical data, after necessary quality controls, were georeferenced and processed in a geochemistry dedicated GIS software named GEODAS. For each considered element a complete set of maps was generated to depict both the discrete and the spatially continuous (interpolated) distribution of elemental concentrations across the region. The interpolated maps were generated using the Multifractal Inverse Distance eighted (MIDW) algorithm. Subsequently, the S-A method, also implemented in GEODAS, was applied to MIDW maps to eliminate spatially limited anomalies from the original grid and to generate the distribution patterns of geochemical baselines for each element. For a selected group of elements geochemical data were also treated by means of a Compositional Data Analysis (CoDA) aiming at investigating the regionalised structure of the data by considering the joint behaviour of several elements constituting for each sample its whole composition. A regional environmental risk assessment was run on the basis of the regional distribution of heavy metals in soil, land use types and population. The risk assessment produced a

  15. Water adsorbate influence on the Cu(110) surface optical response

    NASA Astrophysics Data System (ADS)

    Baghbanpourasl, Amirreza; Schmidt, Wolf Gero; Denk, Mariella; Cobet, Christoph; Hohage, Michael; Zeppenfeld, Peter; Hingerl, Kurt

    2015-11-01

    Surface reflectance anisotropy may be utilized for characterizing surfaces, interfaces, and adsorption structures. Here, the reflectance anisotropy and surface dielectric functions of the thermodynamically most favored water adsorbate structures on the Cu(110) surface (i.e. hexagonal bilayers, pentagonal chains, and partially dissociated water structures) are calculated from density-functional theory and compared with recent experimental data. It is shown that the water overlayer structures modify in a geometry-specific way the optical anisotropy of the bare surface which can be exploited for in situ determination of the adsorption structures. For hexagonal bilayer overlayer geometries, strong features in the vacuum ultraviolet region are predicted. The theoretical analysis shows a noticeable influence of intraband transitions also for higher photon energies and rather slight influences of the van der Waals interaction on the spectral signatures. Water induced strain effects on the surface optical response are found to be negligible.

  16. Implementation of structural response sensitivity calculations in a large-scale finite-element analysis system

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Rogers, J. L., Jr.

    1982-01-01

    The implementation includes a generalized method for specifying element cross-sectional dimensions as design variables that can be used in analytically calculating derivatives of output quantities from static stress, vibration, and buckling analyses for both membrane and bending elements. Limited sample results for static displacements and stresses are presented to indicate the advantages of analytically calclating response derivatives compared to finite difference methods. Continuing developments to implement these procedures into an enhanced version of the system are also discussed.

  17. Laer-induced Breakdown Spectroscopy Instrument for Element Analysis of Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Blacic, J.; Pettit, D.; Cremers, D.; Roessler, N.

    1993-01-01

    One of the most fundamental pieces of information about any planetary body is the elemental and mineralogical composition of its surface materials. We are developing an instrument to obtain such data at ranges of up to several hundreds of meters using the technique of Laser-Induced Breakdown Spectroscopy (LIBS). We envision our instrument being used from a spacecraft in close rendezvous with small bodies such as comets and asteroids, or deployed on surface-rover vehicles on large bodies such as Mars and the Moon. The elemental analysis is based on atomic emission spectroscopy of a laser-induced plasma or spark. A pulsed, diode pumped Nd:YAG laser of several hundred millijoules optical energy is used to vaporize and electronically excite the constituent elements of a rock surface remotely located from the laser. Light emitted from the excited plasma is collected and introduced to the entrance slit of a small grating spectrometer. The spectrally dispersed spark light is detected with either a linear photo diode array or area CCD array. When the latter detector is used, the optical and spectrometer components of the LIBS instrument can also be used in a passive imaging mode to collect and integrate reflected sunlight from the same rock surface. Absorption spectral analysis of this reflected light gives mineralogical information that provides a remote geochemical characterization of the rock surface. We performed laboratory calibrations in air and in vacuum on standard rock powders to quantify the LIBS analysis. We performed preliminary field tests using commercially available components to demonstrate remote LIBS analysis of terrestrial rock surfaces at ranges of over 25 m, and we have demonstrated compatibility with a six-wheeled Russian robotic rover vehicle. Based on these results, we believe that all major and most minor elements expected on planetary surfaces can be measured with absolute accuracy of 10-15 percent and much higher relative accuracy. We have

  18. Major-element composition of Mercury's surface from MESSENGER X-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Weider, S. Z.; Nittler, L. R.; Starr, R. D.; McCoy, T. J.; Boynton, W. V.; Ebel, D. S.; Ernst, C. M.; Evans, L. G.; Goldsten, J. O.; Hamara, D. K.; Lawrence, D. J.; McNutt, R. L.; Schlemm, C. E., II; Solomon, S. C.; Sprague, A. L.

    2011-12-01

    The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission has been in orbit around Mercury since 18 March 2011. The X-Ray Spectrometer (XRS) onboard is revealing the abundances of major elements in the planet's surface for the first time and is thus providing fresh information on Mercury's accretional, differentiation, impact, and geological history. X-rays that emanate from the solar corona during flares excite fluorescent X-rays with characteristic energies from the top ~100 μm of Mercury's surface that are measured by XRS. Forward modelling of the resulting spectra allows elemental abundances for major-elements (Mg, Al, Si, S, Ca, Ti and Fe) to be determined. The data so far show that Mercury's bulk surface composition is distinct from those of the other terrestrial planets, with relatively high Mg/Si and low Al/Si and Ca/Si ratios that lie between those typical of basaltic and ultramafic compositions and are comparable to those for terrestrial komatiites. Derived sulfur abundances are at least ten times higher (up to ~4 wt %) than for the silicate portions of the Earth or Moon, whereas Ti and Fe abundances are low (~0.8 wt % and ~4 wt % respectively). Although the individual footprints for much of the flare data are large, there is compositional heterogeneity across the planet that can be correlated with surface reflectance and geological units. These results, together with the low Fe abundance, indicate that Mercury does not possess a feldspathic flotation crust such as that of the Moon. Rather, it suggests the surface is more likely dominated by lava flows that are products of high-degree partial melting of the mantle. The observations also support the idea that Mercury accreted from highly reduced, but not strongly volatile depleted, precursor materials similar to enstatite chondrites or anhydrous cometary dust particles. The low Fe and Ti abundances seen by XRS do not support the proposal that opaque oxides of these elements are

  19. Regulatory elements responsible for inducible expression of the granulocyte colony-stimulating factor gene in macrophages.

    PubMed Central

    Nishizawa, M; Nagata, S

    1990-01-01

    Granulocyte colony-stimulating factor (G-CSF) plays an essential role in granulopoiesis during bacterial infection. Macrophages produce G-CSF in response to bacterial endotoxins such as lipopolysaccharide (LPS). To elucidate the mechanism of the induction of G-CSF gene in macrophages or macrophage-monocytes, we have examined regulatory cis elements in the promoter of mouse G-CSF gene. Analyses of linker-scanning and internal deletion mutants of the G-CSF promoter by the chloramphenicol acetyltransferase assay have indicated that at least three regulatory elements are indispensable for the LPS-induced expression of the G-CSF gene in macrophages. When one of the three elements was reiterated and placed upstream of the TATA box of the G-CSF promoter, it mediated inducibility as a tissue-specific and orientation-independent enhancer. Although this element contains a conserved NF-kappa B-like binding site, the gel retardation assay and DNA footprint analysis with nuclear extracts from macrophage cell lines demonstrated that nuclear proteins bind to the DNA sequence downstream of the NF-kappa B-like element, but not to the conserved element itself. The DNA sequence of the binding site was found to have some similarities to the LPS-responsive element which was recently identified in the promoter of the mouse class II major histocompatibility gene. Images PMID:1691438

  20. Implementation of an ANCF beam finite element for dynamic response optimization of elastic manipulators

    NASA Astrophysics Data System (ADS)

    Vohar, B.; Kegl, M.; Ren, Z.

    2008-12-01

    Theoretical and practical aspects of an absolute nodal coordinate formulation (ANCF) beam finite element implementation are considered in the context of dynamic transient response optimization of elastic manipulators. The proposed implementation is based on the introduction of new nodal degrees of freedom, which is achieved by an adequate nonlinear mapping between the original and new degrees of freedom. This approach preserves the mechanical properties of the ANCF beam, but converts it into a conventional finite element so that its nodal degrees of freedom are initially always equal to zero and never depend explicitly on the design variables. Consequently, the sensitivity analysis formulas can be derived in the usual manner, except that the introduced nonlinear mapping has to be taken into account. Moreover, the adjusted element can also be incorporated into general finite element analysis and optimization software in the conventional way. The introduced design variables are related to the cross-section of the beam, to the shape of the (possibly) skeletal structure of the manipulator and to the drive functions. The layered cross-section approach and the design element technique are utilized to parameterize the shape of individual elements and the whole structure. A family of implicit time integration methods is adopted for the response and sensitivity analysis. Based on this assumption, the corresponding sensitivity formulas are derived. Two numerical examples illustrate the performance of the proposed element implementation.

  1. Autonomous Aerobraking: Thermal Analysis and Response Surface Development

    NASA Technical Reports Server (NTRS)

    Dec, John A.; Thornblom, Mark N.

    2011-01-01

    A high-fidelity thermal model of the Mars Reconnaissance Orbiter was developed for use in an autonomous aerobraking simulation study. Response surface equations were derived from the high-fidelity thermal model and integrated into the autonomous aerobraking simulation software. The high-fidelity thermal model was developed using the Thermal Desktop software and used in all phases of the analysis. The use of Thermal Desktop exclusively, represented a change from previously developed aerobraking thermal analysis methodologies. Comparisons were made between the Thermal Desktop solutions and those developed for the previous aerobraking thermal analyses performed on the Mars Reconnaissance Orbiter during aerobraking operations. A variable sensitivity screening study was performed to reduce the number of variables carried in the response surface equations. Thermal analysis and response surface equation development were performed for autonomous aerobraking missions at Mars and Venus.

  2. Plant-soil distribution of potentially toxic elements in response to elevated atmospheric CO2.

    PubMed

    Duval, Benjamin D; Dijkstra, Paul; Natali, Susan M; Megonigal, J Patrick; Ketterer, Michael E; Drake, Bert G; Lerdau, Manuel T; Gordon, Gwyneth; Anbar, Ariel D; Hungate, Bruce A

    2011-04-01

    The distribution of contaminant elements within ecosystems is an environmental concern because of these elements' potential toxicity to animals and plants and their ability to hinder microbial ecosystem services. As with nutrients, contaminants are cycled within and through ecosystems. Elevated atmospheric CO2 generally increases plant productivity and alters nutrient element cycling, but whether CO2 causes similar effects on the cycling of contaminant elements is unknown. Here we show that 11 years of experimental CO2 enrichment in a sandy soil with low organic matter content causes plants to accumulate contaminants in plant biomass, with declines in the extractable contaminant element pools in surface soils. These results indicate that CO2 alters the distribution of contaminant elements in ecosystems, with plant element accumulation and declining soil availability both likely explained by the CO2 stimulation of plant biomass. Our results highlight the interdependence of element cycles and the importance of taking a broad view of the periodic table when the effects of global environmental change on ecosystem biogeochemistry are considered.

  3. Dry photopolymer embossing: novel photoreplication technology for surface relief holographic optical elements

    NASA Astrophysics Data System (ADS)

    Shvartsman, Felix P.

    1991-09-01

    Novel photoreplication technology for deep groove surface relief holographic optical elements (HOE) was developed recently at Du Pont. Dry photopolymer embossing (DPE) technology utilizes Du Pont proprietary materials and processes to replicate precisely almost any kind of surface relief or embossed holograms. Very sophisticated surface relief holograms with the high width/depth aspect ratio of 1:20 can be faithfully replicated by this technology. Dimensions of the replicated grooves or other surface relief structures vary from 0.1 micrometers to 3.5 micrometers . Such HOEs can be produced in different geometrical configurations and sizes, which are actually dictated by the master hologram. Embossed HOEs can be fabricated on a plastic film or sheet substrate of different types, thicknesses, and shapes. Glass and other inorganic materials can be also used as substrates in some applications. To replicate such deep groove surface relief HOEs, the master hologram should be recorded in metal, glass, or other hard surface material. DPE technology may provide substantial technological and economical advantages over existing conventional replication processes, such as thermo-embossing, injection molding, wet photopolymerization (2P-process), and injection-reaction molding, in replication of different types of surface relief HOEs.

  4. Bone tissue response to plasma-nitrided titanium implant surfaces

    PubMed Central

    FERRAZ, Emanuela Prado; SVERZUT, Alexander Tadeu; FREITAS, Gileade Pereira; SÁ, Juliana Carvalho; ALVES, Clodomiro; BELOTI, Marcio Mateus; ROSA, Adalberto Luiz

    2015-01-01

    A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces. PMID:25760262

  5. Response Ant Colony Optimization of End Milling Surface Roughness

    PubMed Central

    Kadirgama, K.; Noor, M. M.; Abd Alla, Ahmed N.

    2010-01-01

    Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6) with Response Ant Colony Optimization (RACO). The approach is based on Response Surface Method (RSM) and Ant Colony Optimization (ACO). The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth). The first order model indicates that the feedrate is the most significant factor affecting surface roughness. PMID:22294914

  6. [Response of a finite element model of the pelvis to different side impact loads].

    PubMed

    Ruan, Shijie; Zheng, Huijing; Li, Haiyan; Zhao, Wei

    2013-08-01

    The pelvis is one of the most likely affected areas of the human body in case of side impact, especially while people suffer from motor vehicle crashes. With the investigation of pelvis injury on side impact, the injury biomechanical behavior of pelvis can be found, and the data can help design the vehicle security devices to keep the safety of the occupants. In this study, a finite element (FE) model of an isolated human pelvis was used to study the pelvic dynamic response under different side impact conditions. Fracture threshold was established by applying lateral loads of 1000, 2000, 3000, 4000 and 5000 N, respectively, to the articular surface of the right acetabulum. It was observed that the smaller the lateral loads were, the smaller the von Mises stress and the displacement in the direction of impact were. It was also found that the failure threshold load was near 3000 N, based on the fact that the peak stress would not exceed the average compressive strength of the cortical bone. It could well be concluded that with better design of car-door and hip-pad so that the side impact force was brought down to 3000 N or lower, the pelvis would not be injured.

  7. Establishing a statistic model for recognition of steroid hormone response elements.

    PubMed

    Stepanova, Maria; Lin, Feng; Lin, Valerie C-L

    2006-10-01

    Identification of hormone response elements (HREs) is essential for understanding the mechanism of hormone-regulated gene expression. To date, there has been a lack of effective bioinformatics tools for recognition of specific HRE such as Progesterone Response Elements (PRE). In this paper, a comprehensive survey and comparison of in silico methods is conducted for establishing a more accurate statistic model. Homogeneity of steroid HRE is analyzed and a reliable training dataset is constructed through extensive searching for experimentally validated response elements from more than 150 literature sources. Based on the observation that the verified HREs carry di-nucleotide preservation in comparison with uniform nucleotide distributions, both mono and di-nucleotide Position Weight Matrices are computed to extract the statistic pattern of the positions. It is followed by the sequence transition pattern recognition using a specifically designed profile Hidden Markov Model. Reciprocal combination of the statistic and transition patterns significantly improves the performance of the model in terms of higher sensitivity and specificity. Upon acquisition of the putative response elements in the promoter areas of vertebrate genes, a qualitative scheme is applied to assess the probability for each gene to be a hormone primary target. Using >650 records of experimentally validated steroid hormone response elements, a high sensitivity level of 73% and high specificity level of one prediction per 8.24 kb is reached, allowing this model to be used for further prediction of primary target genes through the analysis of their upstream promoters, for human or other vertebrate genomes of interest. Additional documents, supplementary data and the web-based program developed for response elements prediction are freely available for academic research at . Submission of putative gene promoter regions for recognition of potential regulatory PREs can be as long as 5 kb.

  8. The Periosteal Bone Surface is Less Mechano-Responsive than the Endocortical

    NASA Astrophysics Data System (ADS)

    Birkhold, Annette I.; Razi, Hajar; Duda, Georg N.; Weinkamer, Richard; Checa, Sara; Willie, Bettina M.

    2016-03-01

    Dynamic processes modify bone micro-structure to adapt to external loading and avoid mechanical failure. Age-related cortical bone loss is thought to occur because of increased endocortical resorption and reduced periosteal formation. Differences in the (re)modeling response to loading on both surfaces, however, are poorly understood. Combining in-vivo tibial loading, in-vivo micro-tomography and finite element analysis, remodeling in C57Bl/6J mice of three ages (10, 26, 78 week old) was analyzed to identify differences in mechano-responsiveness and its age-related change on the two cortical surfaces. Mechanical stimulation enhanced endocortical and periosteal formation and reduced endocortical resorption; a reduction in periosteal resorption was hardly possible since it was low, even without additional loading. Endocortically a greater mechano-responsiveness was identified, evident by a larger bone-forming surface and enhanced thickness of formed bone packets, which was not detected periosteally. Endocortical mechano-responsiveness was better conserved with age, since here adaptive response declined continuously with aging, whereas periosteally the main decay in formation response occurred already before adulthood. Higher endocortical mechano-responsiveness is not due to higher endocortical strains. Although it is clear structural adaptation varies between different bones in the skeleton, this study demonstrates that adaptation varies even at different sites within the same bone.

  9. The Periosteal Bone Surface is Less Mechano-Responsive than the Endocortical.

    PubMed

    Birkhold, Annette I; Razi, Hajar; Duda, Georg N; Weinkamer, Richard; Checa, Sara; Willie, Bettina M

    2016-01-01

    Dynamic processes modify bone micro-structure to adapt to external loading and avoid mechanical failure. Age-related cortical bone loss is thought to occur because of increased endocortical resorption and reduced periosteal formation. Differences in the (re)modeling response to loading on both surfaces, however, are poorly understood. Combining in-vivo tibial loading, in-vivo micro-tomography and finite element analysis, remodeling in C57Bl/6J mice of three ages (10, 26, 78 week old) was analyzed to identify differences in mechano-responsiveness and its age-related change on the two cortical surfaces. Mechanical stimulation enhanced endocortical and periosteal formation and reduced endocortical resorption; a reduction in periosteal resorption was hardly possible since it was low, even without additional loading. Endocortically a greater mechano-responsiveness was identified, evident by a larger bone-forming surface and enhanced thickness of formed bone packets, which was not detected periosteally. Endocortical mechano-responsiveness was better conserved with age, since here adaptive response declined continuously with aging, whereas periosteally the main decay in formation response occurred already before adulthood. Higher endocortical mechano-responsiveness is not due to higher endocortical strains. Although it is clear structural adaptation varies between different bones in the skeleton, this study demonstrates that adaptation varies even at different sites within the same bone.

  10. The Periosteal Bone Surface is Less Mechano-Responsive than the Endocortical

    PubMed Central

    Birkhold, Annette I.; Razi, Hajar; Duda, Georg N.; Weinkamer, Richard; Checa, Sara; Willie, Bettina M.

    2016-01-01

    Dynamic processes modify bone micro-structure to adapt to external loading and avoid mechanical failure. Age-related cortical bone loss is thought to occur because of increased endocortical resorption and reduced periosteal formation. Differences in the (re)modeling response to loading on both surfaces, however, are poorly understood. Combining in-vivo tibial loading, in-vivo micro-tomography and finite element analysis, remodeling in C57Bl/6J mice of three ages (10, 26, 78 week old) was analyzed to identify differences in mechano-responsiveness and its age-related change on the two cortical surfaces. Mechanical stimulation enhanced endocortical and periosteal formation and reduced endocortical resorption; a reduction in periosteal resorption was hardly possible since it was low, even without additional loading. Endocortically a greater mechano-responsiveness was identified, evident by a larger bone-forming surface and enhanced thickness of formed bone packets, which was not detected periosteally. Endocortical mechano-responsiveness was better conserved with age, since here adaptive response declined continuously with aging, whereas periosteally the main decay in formation response occurred already before adulthood. Higher endocortical mechano-responsiveness is not due to higher endocortical strains. Although it is clear structural adaptation varies between different bones in the skeleton, this study demonstrates that adaptation varies even at different sites within the same bone. PMID:27004741

  11. Finite-element analysis of earing using non-quadratic yield surfaces

    SciTech Connect

    Logan, R.W.

    1995-06-18

    During deep draw cupping, the phenomenon known as earing may occur as the cup wall is formed, resulting in a periodic variation of cup wall height around the perimeter of the finished cup. This is generally due to planar anisotropy of flow in rolled sheet product. It is generally observed that the anisotropy parameter R will vary in the plane of the sheet when ears are observed in cupping, with a parameter {Delta}R describing the variation of R in the plane of the sheet. For many common textures in face-centered and body-centered materials, the ears form relative to the sheet rolling direction at 0{degrees} and 90{degrees} around the perimeter if {Delta}R>0, and at -45{degrees} and +45{degrees} if {Delta}R<0. There is extensive experimental evidence that ear height shows a linear correlation with {Delta}R/R, but attempts to duplicate this using the finite-element method are highly dependent on both the methodology and yield surface used. It was shown previously that using a coarse mesh and the quadratic Hill yield surface tends to greatly under predict earing. In this study, we have used two different finite-element codes developed at LLNL to examine the predicted earing using both quadratic Hill and alternative non-quadratic yield surfaces. These results are compared to experimental data and conclusions drawn about the most desirable closed-form yield surfaces to duplicate the observed earing phenomena.

  12. Modeling of electrohydrodynamic drying process using response surface methodology

    PubMed Central

    Dalvand, Mohammad Jafar; Mohtasebi, Seyed Saeid; Rafiee, Shahin

    2014-01-01

    Energy consumption index is one of the most important criteria for judging about new, and emerging drying technologies. One of such novel and promising alternative of drying process is called electrohydrodynamic (EHD) drying. In this work, a solar energy was used to maintain required energy of EHD drying process. Moreover, response surface methodology (RSM) was used to build a predictive model in order to investigate the combined effects of independent variables such as applied voltage, field strength, number of discharge electrode (needle), and air velocity on moisture ratio, energy efficiency, and energy consumption as responses of EHD drying process. Three-levels and four-factor Box–Behnken design was employed to evaluate the effects of independent variables on system responses. A stepwise approach was followed to build up a model that can map the entire response surface. The interior relationships between parameters were well defined by RSM. PMID:24936289

  13. Dynamic simulation of free surfaces in capillaries with the finite element method

    NASA Astrophysics Data System (ADS)

    Trutschel, R.; Schellenberger, U.

    1998-02-01

    The mathematical formulation of the dynamics of free liquid surfaces including the effects of surface tension is governed by a non-linear system of elliptic differential equations. The major difficulty of getting unique closed solutions only in trivial cases is overcome by numerical methods. This paper considers transient simulations of liquid-gas menisci in vertical capillary tubes and gaps in the presence of gravity. Therefore the CFD code FIDAP 7.52 based on the Galerkin finite element method (FEM) is used. Calculations using the free surface model are presented for a variety of contact angles and cross-sections with experimental and theoretical verification. The liquid column oscillations are compared for numerical accuracy with a mechanical mathematical model, and the sensitivity with respect to the node density is investigated. The efficiency of the numerical treatment of geometric non-trivial problems is demonstrated by a prismatic capillary. Present restrictions limiting efficient transient simulations with irregularly shaped calculational domains are stated.

  14. The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry.

    PubMed

    Nittler, Larry R; Starr, Richard D; Weider, Shoshana Z; McCoy, Timothy J; Boynton, William V; Ebel, Denton S; Ernst, Carolyn M; Evans, Larry G; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Schlemm, Charles E; Solomon, Sean C; Sprague, Ann L

    2011-09-30

    X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance. PMID:21960623

  15. The major-element composition of Mercury's surface from MESSENGER X-ray spectrometry.

    PubMed

    Nittler, Larry R; Starr, Richard D; Weider, Shoshana Z; McCoy, Timothy J; Boynton, William V; Ebel, Denton S; Ernst, Carolyn M; Evans, Larry G; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Schlemm, Charles E; Solomon, Sean C; Sprague, Ann L

    2011-09-30

    X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury's low and variable surface reflectance.

  16. Effects of extreme pressure additive chemistry on rolling element bearing surface durability

    SciTech Connect

    Evans, Ryan D.; Nixon, H. P.; Darragh, Craig V.; Howe, Jane Y; Coffey, Dorothy W

    2007-01-01

    Lubricant additives have been known to affect rolling element bearing surface durability for many years. Tapered roller bearings were used in fatigue testing of lubricants formulated with gear oil type additive systems. These systems have sulfur- and phosphoruscontaining compounds used for gear protection as well as bearing lubrication. Several variations of a commercially available base additive formulation were tested having modified sulfur components. The variations represent a range of ''active'' extreme pressure (EP) chemistries. The bearing fatigue test results were compared with respect to EP formulation and test conditions. Inner ring near-surface material in selected test bearings was evaluated on two scales: the micrometer scale using optical metallography and the nanometer scale using transmission electron microscopy (TEM). Focused-ion beam (FIB) techniques were used for TEM specimen preparation. Imaging and chemical analysis of the bearing samples revealed near-surface material and tribofilm characteristics. These results are discussed with respect to the relative fatigue lives.

  17. Assessment of Response Surface Models using Independent Confirmation Point Analysis

    NASA Technical Reports Server (NTRS)

    DeLoach, Richard

    2010-01-01

    This paper highlights various advantages that confirmation-point residuals have over conventional model design-point residuals in assessing the adequacy of a response surface model fitted by regression techniques to a sample of experimental data. Particular advantages are highlighted for the case of design matrices that may be ill-conditioned for a given sample of data. The impact of both aleatory and epistemological uncertainty in response model adequacy assessments is considered.

  18. Hydrophilic-oleophobic stimuli-responsive materials and surfaces

    NASA Astrophysics Data System (ADS)

    Howarter, John A.

    Due to their high surface energy, hydrophilic surfaces are susceptible to contamination which is difficult to remove and often ruins the surface. Hydrophilic-oleophobic coatings have a diverse engineering potential including applications as self-cleaning surfaces, extended life anti-fog coatings, and environmental remediation in the selective filtration of oil-in-water mixtures. A successful design model for hydrophilic-oleophobic behavior has been developed using perfluorinated surfactants covalently bound to a surface. Within this design model, a variety of materials have been explored which the surfactants are covalently bound to a substrate; similarly, the surfactants may also be incorporated as a monomer into bulk copolymers. Surfactant based surfaces exhibited simultaneous hydrophilicity, necessary for anti-fogging, and oleophobicity, necessary for contamination resistance. The combination of these features rendered the surface as self-cleaning. Surfactant based brushes, composed of polyethylene glycol and perfluorinated constituents were grafted on to silica surfaces. The relationship between brush density and stimuli-responsiveness was determined by varying grafting conditions. The resultant surfaces were characterized with respect to chemical composition, brush thickness, and wetting behavior of water and hexadecane. Optimized surfaces exhibited stimuli-responsive behavior such that the surfaces will be wetted by water but not by oil. Surfactants were incorporated into random copolymers to create self-cleaning polymers which could be easily coated on to surfaces post-synthesis. Acrylic acid, methyl methacrylate, and hydroxyethyl methacrylate were used as comonomers; feed ratio was varied to establish compositional limits of stimuli-responsive behavior. Polymer composition dictated coating durability and self-cleaning performance as determined by water and hexadecane contact angle. The ability of select coatings to mitigate fogging was assessed in two

  19. Elemental composition of the lunar surface: Analysis of gamma ray spectroscopy data from Lunar Prospector

    NASA Astrophysics Data System (ADS)

    Prettyman, T. H.; Hagerty, J. J.; Elphic, R. C.; Feldman, W. C.; Lawrence, D. J.; McKinney, G. W.; Vaniman, D. T.

    2006-12-01

    Gamma ray spectroscopy data acquired by Lunar Prospector are used to determine global maps of the elemental composition of the lunar surface. Maps of the abundance of major oxides, MgO, Al2O3, SiO2, CaO, TiO2, and FeO, and trace incompatible elements, K and Th, are presented along with their geochemical interpretation. Linear spectral mixing is used to model the observed gamma ray spectrum for each map pixel. The spectral shape for each elemental constituent is determined by a Monte Carlo radiation transport calculation. Linearization of the mixing model is accomplished by scaling the spectral shapes with lunar surface parameters determined by neutron spectroscopy, including the number density of neutrons slowing down within the surface and the effective atomic mass of the surface materials. The association of the highlands with the feldspathic lunar meteorites is used to calibrate the mixing model and to determine backgrounds. A linear least squares approach is used to unmix measured spectra to determine the composition of each map pixel. The present analysis uses new gamma ray production cross sections for neutron interactions, resulting in improved accuracy compared to results previously submitted to the Planetary Data System. Systematic variations in lunar composition determined by the spectral unmixing analysis are compared with the lunar soil sample and meteorite collections. Significant results include improved accuracy for the abundance of Th and K in the highlands; identification of large regions, including western Procellarum, that are not well represented by the sample collection; and the association of relatively high concentrations of Mg with KREEP-rich regions on the lunar nearside, which may have implications for the concept of an early magma ocean.

  20. Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.; Simon, Charles G.

    1991-01-01

    Hypervelocity impact features on several of the electro-active dust sensors utilized in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microprobe. The negatively biased dust sensor surfaces acted as ion traps for cations produced in the plasma plumes of impacting particles. Impactor residue surrounds most impact features to two or three feature diameters. After etching away a layer of carbonaceous/silicaceous surface contamination, low mass resolution elemental survey scans are used to tentatively identify the presence of impactor debris. High mass resolution two-dimensional elemental maps and three dimensional depth profiling of the feature and surrounding area show the distribution and relative composition of the debris. The location of these sensors on the six primary Long Duration Exposure Facility (LDEF) sides provides a unique opportunity to further define the debris environment. Researchers applied the same techniques to impact and contaminant features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on row 12 and exposed to the environment during the entire mission.

  1. The Effects of Surface Roughness on the NEAR XRS Elemental Results: Monte-Carlo Modeling

    NASA Technical Reports Server (NTRS)

    Lin, Lucy F.; Nittler, Larry R.

    2011-01-01

    The objective of the NEAR-Shoemaker X-ray Gamma-Ray Spec1roscopy ("XGRS") investigation was to determine the elemental composition of the near-Earth asteroid 433 Eros. The X-ray Spectrometer (XRS) system measured the characteristic fluorescence of six major elements (Mg, Al, Si, S, Ca, Fe) in the 1-10 keV energy range excited by the interaction of solar X-rays with the upper 100 microns of the surface of 433 Eros. Various investigators, using both laboratory experiments and computer simulations have established that X-ray fluorescent line ratios can be influenced by small-scale surface roughness at high incidence or emission angles. The effect on the line ratio is specific to the geometry, excitation spectrum, and composition involved, In general, however, the effect is only substantial for ratios of lines with a significant energy difference between them: Fe/Si and Ca/Si are much more likely to be affected than AI/Si or Mg/Si. We apply a Monte-Carlo code to the specific geometry and spectrum of a major NEAR XRS solar flare observation, using an H chondrite composition as the substrate. The seventeen most abundant elements were included in the composition model, from oxygen to titanium.

  2. Boundary element analysis of packed silencers with protective cloth and embedded thin surfaces

    NASA Astrophysics Data System (ADS)

    Wu, T. W.; Cheng, C. Y. R.; Tao, Z.

    2003-03-01

    Bulk-reacting porous materials are often used as absorptive lining in packed silencers to reduce broadband noise. Modelling the entire silencer domain with a bulk-reacting material will inevitably involve two different acoustic media, air and the bulk-reacting material. A so-called direct mixed-body boundary element method (BEM) has recently been developed to model the two-medium problem in a single-domain fashion. The present paper is an extension of the direct mixed-body BEM to include protective cloth and embedded rigid surfaces. Protective cloth, an absorptive material itself with a higher flow resistivity than the primary lining material, is usually sandwiched between a perforated metal surface and the lining to protect the lining material from any abrasive effect of the grazing flow. Two different approaches are taken to model the protective cloth. One is to approximate sound pressure as a linear function across the cloth thickness and then use the bulk-reacting material properties of the cloth to obtain the transfer impedance. The other is to measure the transfer impedance of the cloth directly by an experimental set-up similar to the two-cavity method. As for an embedded thin surface, it is a rigid thin surface sandwiched between two bulk-reacting linings. Numerical modelling of an embedded thin surface is similar to the modelling of a rigid thin surface in air. Several test cases are given and the BEM results for transmission loss (TL) are verified by experimental TL measurements.

  3. Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac-Coulomb atomic calculations.

    PubMed

    Pershina, V; Borschevsky, A; Eliav, E; Kaldor, U

    2008-10-14

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the largest, 4.55 a.u. These extreme values reflect, in addition to the general trends in the Periodic Table, the relativistic expansion and destabilization of the outer valence 7p(3/2) orbital. Van der Waals coefficients C(3) and adsorption enthalpies DeltaH(ads) of Ne through element 118 on noble metals and inert surfaces, such as quartz, ice, Teflon, and graphite, were calculated in a physisorption model using the atomic properties obtained. The C(3) coefficients were shown to steadily increase in group 18, while the increase in DeltaH(ads) from Ne to Rn does not continue to element 118: The large atomic radius of the latter element is responsible for a decrease in the interaction energy. We therefore predict that experimental distinction between Rn and 118 by adsorption on these types of surfaces will not be feasible. A possible candidate for separating the two elements is charcoal; further study is needed to test this possibility.

  4. Active muscle response using feedback control of a finite element human arm model.

    PubMed

    Östh, Jonas; Brolin, Karin; Happee, Riender

    2012-01-01

    Mathematical human body models (HBMs) are important research tools that are used to study the human response in car crash situations. Development of automotive safety systems requires the implementation of active muscle response in HBM, as novel safety systems also interact with vehicle occupants in the pre-crash phase. In this study, active muscle response was implemented using feedback control of a nonlinear muscle model in the right upper extremity of a finite element (FE) HBM. Hill-type line muscle elements were added, and the active and passive properties were assessed. Volunteer tests with low impact loading resulting in elbow flexion motions were performed. Simulations of posture maintenance in a gravity field and the volunteer tests were successfully conducted. It was concluded that feedback control of a nonlinear musculoskeletal model can be used to obtain posture maintenance and human-like reflexive responses in an FE HBM.

  5. Size fractionation of trace elements in the surface water and groundwater of the Ganjiang River and Xiushui River basins, China

    NASA Astrophysics Data System (ADS)

    Soldatova, E. A.; Guseva, N. V.; Sun, Z.; Mazurova, I. S.

    2015-11-01

    The research of trace element behaviour and size fractionation is significant to understand the processes in the water-rock system. Moreover, the aqueous speciation of trace elements is strongly related to their distribution and toxicity. In this research, trace elements behaviour and their size fractionation are investigated in the natural water (the surface water and shallow groundwater) of the Ganjiang River and Xiushui River basins. Trace element concentrations were measured by ICP-MS. The authors estimated the size fractionation of the trace elements between suspended forms (>0.45μm) and dissolved fractions, which included truly dissolved (1 kDa) and colloidal particles (0.45μm-1 kDa)), after filtration through a 0.45 μm acetate cellulose membrane filter. The distinct features of the trace element size fractionation were identified. The size fractionation of the trace elements under different conditions (in the surface water and shallow groundwater) was studied.

  6. Response Surface Model Building Using Orthogonal Arrays for Computer Experiments

    NASA Technical Reports Server (NTRS)

    Unal, Resit; Braun, Robert D.; Moore, Arlene A.; Lepsch, Roger A.

    1997-01-01

    This study investigates response surface methods for computer experiments and discusses some of the approaches available. Orthogonal arrays constructed for computer experiments are studied and an example application to a technology selection and optimization study for a reusable launch vehicle is presented.

  7. Effect of design selection on response surface performance

    NASA Technical Reports Server (NTRS)

    Carpenter, William C.

    1993-01-01

    The mathematical formulation of the engineering optimization problem is given. Evaluation of the objective function and constraint equations can be very expensive in a computational sense. Thus, it is desirable to use as few evaluations as possible in obtaining its solution. In solving the equation, one approach is to develop approximations to the objective function and/or restraint equations and then to solve the equation using the approximations in place of the original functions. These approximations are referred to as response surfaces. The desirability of using response surfaces depends upon the number of functional evaluations required to build the response surfaces compared to the number required in the direct solution of the equation without approximations. The present study is concerned with evaluating the performance of response surfaces so that a decision can be made as to their effectiveness in optimization applications. In particular, this study focuses on how the quality of approximations is effected by design selection. Polynomial approximations and neural net approximations are considered.

  8. Determination of copper, scandium, molybdenum, tin, lead, and iron group elements in lunar surface materials

    NASA Technical Reports Server (NTRS)

    Pavlenko, L. I.; Simonova, L. V.; Karyakin, A. V.

    1974-01-01

    Distribution regularities of copper, scandium, molybdenum, tin, lead, and iron group elements were investigated in basaltoid rocks of lunar and terrestrial origin. Samples of various regolith zones taken in the area of the Sea of Fertility were analyzed, along with samples of basic and ultrabasic rocks of the East African Rift for their content of the trace admixtures listed. Data obtained on the abundance of copper, scandium, molybdenum, tin, lead, cobalt, nickel, chromium, and vanadium in Luna 16 lunar surface material were compared with the abundance of these elements in samples of lunar rocks returned by Apollo 11, Apollo 12, and Apollo 14, with the exception of scandium; its content in the latter samples was considerably higher.

  9. Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution.

    PubMed

    Peplowski, Patrick N; Evans, Larry G; Hauck, Steven A; McCoy, Timothy J; Boynton, William V; Gillis-Davis, Jeffery J; Ebel, Denton S; Goldsten, John O; Hamara, David K; Lawrence, David J; McNutt, Ralph L; Nittler, Larry R; Solomon, Sean C; Rhodes, Edgar A; Sprague, Ann L; Starr, Richard D; Stockstill-Cahill, Karen R

    2011-09-30

    The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since. PMID:21960624

  10. Tunable photonic elements at the surface of an optical fiber with piezoelectric core.

    PubMed

    Dmitriev, A V; Sumetsky, M

    2016-05-15

    Tunable photonic elements at the surface of an optical fiber with piezoelectric core are proposed and analyzed theoretically. These elements are based on whispering gallery modes whose propagation along the fiber is fully controlled by nanoscale variation of the effective fiber radius, which can be tuned by means of a piezoelectric actuator embedded into the core. The developed theory allows one to express the introduced effective radius variation through the shape of the actuator and the voltage applied to it. In particular, the designs of a miniature tunable optical delay line and a miniature tunable dispersion compensator are presented. The potential application of the suggested model to the design of a miniature optical buffer is also discussed. PMID:27176953

  11. Non-contact high precision measurement of surface form tolerances and central thickness for optical elements

    NASA Astrophysics Data System (ADS)

    Lou, Ying

    2010-10-01

    The traditional contact measuring methods could not satisfy the current optical elements measuring requirements. Noncontact high precision measuring theory, principle and instrument of the surface form tolerances and central thickness for optical elements were studied in the paper. In comparison with other types of interferometers, such as Twyman-Green and Mach-Zehnder, a Fizeau interferometer has the advantages of having fewer optical components, greater accuracy, and is easier to use. Some relations among the 3/A(B/C), POWER/PV and N/ΔN were studied. The PV with POWER removed can be the reference number of ΔN. The chromatic longitudinal aberration of a special optical probe can be used for non-contanct central thickness measurement.

  12. Bacteria responsive antibacterial surfaces for indwelling device infections.

    PubMed

    Traba, Christian; Liang, Jun F

    2015-01-28

    Indwelling device infections now represent life-threatening circumstances as a result of the biofilms' tolerance to antibiotic treatments. Current antibiotic impregnation approaches through sustained antibiotic release have some unsolved problems which include short life-span, narrowed antibacterial spectrum, ineffectiveness towards resistant mutants, and the potential to hasten the antibiotic resistance process. In this study, bacteria responsive anti-biofilm surfaces were developed using bioactive peptides with proved activity to antibiotic resistant bacteria and biofilms. Resulting surfaces were stable under physiological conditions and in the presence of high concentrations of salts (0.5M NaCl) and biomacromolcules (1.0% DNA and 2.0% alginate), and thus showed good biocompatibility to various tissue cells. However, lytic peptide immobilized surfaces could sense bacteria adhesion and kill attached bacteria effectively and specifically, so biofilms were unable to develop on the lytic peptide immobilized surfaces. Bacteria responsive catheters remained biofilm free for up to a week. Therefore, the bacteria responsive antibacterial surfaces developed in this study represent new opportunities for indwelling device infections.

  13. Bacteria Responsive Antibacterial Surfaces for Indwelling Device Infections

    PubMed Central

    Traba, Christian; Liang, Jun F.

    2014-01-01

    Indwelling device infections now represents life-threatening circumstances as a result of the biofilms’ tolerance to antibiotic treatments. Current antibiotic impregnation approaches through sustained antibiotic release have some unsolved problems which include short life-span, narrowed antibacterial spectrum, ineffectiveness towards resistant mutants, and the potential to hasten the antibiotic resistance process. In this study, bacteria responsive anti-biofilm surfaces were developed using bioactive peptides with proved activity to antibiotic resistant bacteria and biofilms. Resulting surfaces were stable under physiological conditions and in the presence of high concentrations of salts (0.5 M NaCl) and biomacromolcules (1.0% DNA and 2.0% alginate), and thus showed good biocompatibility to various tissue cells. However, lytic peptide immobilized surfaces could sense bacteria adhesion and kill attached bacteria effectively and specifically, so biofilms were unable to develop on the lytic peptide immobilized surfaces. Bacteria responsive catheters remained biofilm free for up to a week. Therefore, the bacteria responsive antibacterial surfaces developed in this study represent new opportunities for indwelling device infections. PMID:25481445

  14. Bacteria responsive antibacterial surfaces for indwelling device infections.

    PubMed

    Traba, Christian; Liang, Jun F

    2015-01-28

    Indwelling device infections now represent life-threatening circumstances as a result of the biofilms' tolerance to antibiotic treatments. Current antibiotic impregnation approaches through sustained antibiotic release have some unsolved problems which include short life-span, narrowed antibacterial spectrum, ineffectiveness towards resistant mutants, and the potential to hasten the antibiotic resistance process. In this study, bacteria responsive anti-biofilm surfaces were developed using bioactive peptides with proved activity to antibiotic resistant bacteria and biofilms. Resulting surfaces were stable under physiological conditions and in the presence of high concentrations of salts (0.5M NaCl) and biomacromolcules (1.0% DNA and 2.0% alginate), and thus showed good biocompatibility to various tissue cells. However, lytic peptide immobilized surfaces could sense bacteria adhesion and kill attached bacteria effectively and specifically, so biofilms were unable to develop on the lytic peptide immobilized surfaces. Bacteria responsive catheters remained biofilm free for up to a week. Therefore, the bacteria responsive antibacterial surfaces developed in this study represent new opportunities for indwelling device infections. PMID:25481445

  15. Trace element speciation and origin of colloids in surface waters of subarctic zone (NW of Russia and Central Siberia)

    NASA Astrophysics Data System (ADS)

    Pokrovsky, O. S.; Viers, J.; Prokushkin, A. S.; Vasukova, E. V.; Shirokova, L. S.; Dupre, B.

    2008-12-01

    Geochemistry of trace elements (TE) in boreal regions attracts large attention of researchers in view of on- going environmental changes that can affect both the fluxes of these elements to the ocean, their speciation and thus their bioavailability. Most of trace elements in waters of boreal zone are transported via organic and organo-mineral colloids. In order to better understand the processes of colloids formation in surface waters draining watersheds of various lithology and permafrost abundance, comparative study of TE speciation in various geographic zones is necessary. In this work we attempted to generalize the typical features of trace element speciation in boreal arctic and subarctic zones assessed via in-situ dialysis and ultrafiltration. Surface waters of three circumpolar regions in Arkhangelsk region, NW Russia and Central Siberia were studied using unique and rigorous procedure via combination of in-situ dialysis and ultrafiltration (1 kDa, 3.5 kDa, 10 kDa, 100 kDa, 0.22 µm, 0.45 µm, 1 μm, 5 µm). In both filtrates and dialysates, all major and trace elements and dissolved organic carbon were analyzed. In all studied regions, three typical features of colloid speciation have been revealed: i) high proportion of large-size colloids (10 kDa - 0.22 μm and 0.22 μm - 5 µm), mostly composed of Fe oxy(hydr)oxides stabilized by organic matter; ii) presence of organic-rich, small size colloids and conventionally "dissolved" substances (< 1 kDa and 1 - 10 kDa), presumably, fulvic acids, and iii) strong association of all trivalent and tetravalent elements with large-size mineral colloids. Results of the present work allow distinguishing between two possible pathways of colloids formation: 1) Groundwater-borne Fe(II) oxidation and TE coprecipitation in the presence of organic matter originated from plant litter and peat layers of surface horizons at the surface redox front between anoxic groundwaters and surficial OM-rich waters of the riparian zone, and

  16. Rapid design of LED optical elements with two free-form surfaces generating uniformly illuminated rectangular area

    NASA Astrophysics Data System (ADS)

    Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kravchenko, Sergey V.

    2013-09-01

    Design of LED optical elements producing uniform illumination in rectangular regions is one of the most actual and challenging problems in development of lighting devices. As a rule, LED optical element has at least two surfaces (inner and outer) that leads to computational complexity of design process and requires application of different optimization techniques. We present a new rapid computational method for automatical design of optical elements with two free-form surfaces which generate uniform irradiance distribution in the rectangular region. Such optical elements have high lighting efficiency (about 92 %) and can be produced by injection molding.

  17. Pounding Effects on the Earthquake Response of Adjacent Reinforced Concrete Structures Strengthened by Cable Elements

    NASA Astrophysics Data System (ADS)

    Liolios, Angelos; Liolios, Asterios; Hatzigeorgiou, George; Radev, Stefan

    2014-06-01

    A numerical approach for estimating the effects of pounding (seismic interaction) on the response of adjacent Civil Engineering structures is presented. Emphasis is given to reinforced concrete (RC) frames of existing buildings which are seismically strengthened by cable-elements. A double discretization, in space by the Finite Element Method and in time by a direct incremental approach is used. The unilateral behaviours of both, the cable-elements and the interfaces contact-constraints, are taken strictly into account and result to inequality constitutive conditions. So, in each time-step, a non-convex linear complementarity problem is solved. It is found that pounding and cable strengthening have significant effects on the earthquake response and, hence, on the seismic upgrading of existing adjacent RC structures.

  18. Are collapsars responsible for some r-process elements? How could we tell?

    SciTech Connect

    Pruet, J

    2004-04-05

    We consider the possibility that supernovae which form hyper-accreting black holes might be responsible for synthesis of r-process elements with mass A {approx}< 130. Calculations are presented which show that these elements are naturally synthesized in neutron-rich magnetically-dominated bubbles born in the inner regions of a black hole accretion disk. Simple considerations suggest that the total mass ejected in the form of these bubbles is about that needed to account for the entire galactic inventory of the 2nd-peak r-process elements. We also argue that if collapsars are responsible for, e.g., Ag synthesis, then Ag abundances should be correlated with Sc and/or Zn abundances in metal-poor stars.

  19. Response of hot element flush wall gauges in oscillating laminar flow

    NASA Technical Reports Server (NTRS)

    Giddings, T. A.; Cook, W. J.

    1986-01-01

    The time dependent response characteristics of flush-mounted hot element gauges used as instruments to measure wall shear stress in unsteady periodic air flows were investigated. The study was initiated because anomalous results were obtained from the gauges in oscillating turbulent flows for the phase relation of the wall shear stress variation, indicating possible gauge response problems. Flat plate laminar oscillating turbulent flows characterized by a mean free stream velocity with a superposed sinusoidal variation were performed. Laminar rather than turbulent flows were studied, because a numerical solution for the phase angle between the free stream velocity and the wall shear stress variation that is known to be correct can be obtained. The focus is on comparing the phase angle indicated by the hot element gauges with corresponding numerical prediction for the phase angle, since agreement would indicate that the hot element gauges faithfully follow the true wall shear stress variation.

  20. Investigating the functionality of an OCT4-short response element in human induced pluripotent stem cells.

    PubMed

    Vega-Crespo, Agustin; Truong, Brian; Hermann, Kip J; Awe, Jason P; Chang, Katherine M; Lee, Patrick C; Schoenberg, Benjamen E; Wu, Lily; Byrne, James A; Lipshutz, Gerald S

    2016-01-01

    Pluripotent stem cells offer great therapeutic promise for personalized treatment platforms for numerous injuries, disorders, and diseases. Octamer-binding transcription factor 4 (OCT4) is a key regulatory gene maintaining pluripotency and self-renewal of mammalian cells. With site-specific integration for gene correction in cellular therapeutics, use of the OCT4 promoter may have advantages when expressing a suicide gene if pluripotency remains. However, the human OCT4 promoter region is 4 kb in size, limiting the capacity of therapeutic genes and other regulatory components for viral vectors, and decreasing the efficiency of homologous recombination. The purpose of this investigation was to characterize the functionality of a novel 967bp OCT4-short response element during pluripotency and to examine the OCT4 titer-dependent response during differentiation to human derivatives not expressing OCT4. Our findings demonstrate that the OCT4-short response element is active in pluripotency and this activity is in high correlation with transgene expression in vitro, and the OCT4-short response element is inactivated when pluripotent cells differentiate. These studies demonstrate that this shortened OCT4 regulatory element is functional and may be useful as part of an optimized safety component in a site-specific gene transferring system that could be used as an efficient and clinically applicable safety platform for gene transfer in cellular therapeutics. PMID:27500178

  1. Investigating the functionality of an OCT4-short response element in human induced pluripotent stem cells

    PubMed Central

    Vega-Crespo, Agustin; Truong, Brian; Hermann, Kip J; Awe, Jason P; Chang, Katherine M; Lee, Patrick C; Schoenberg, Benjamen E; Wu, Lily; Byrne, James A; Lipshutz, Gerald S

    2016-01-01

    Pluripotent stem cells offer great therapeutic promise for personalized treatment platforms for numerous injuries, disorders, and diseases. Octamer-binding transcription factor 4 (OCT4) is a key regulatory gene maintaining pluripotency and self-renewal of mammalian cells. With site-specific integration for gene correction in cellular therapeutics, use of the OCT4 promoter may have advantages when expressing a suicide gene if pluripotency remains. However, the human OCT4 promoter region is 4 kb in size, limiting the capacity of therapeutic genes and other regulatory components for viral vectors, and decreasing the efficiency of homologous recombination. The purpose of this investigation was to characterize the functionality of a novel 967bp OCT4-short response element during pluripotency and to examine the OCT4 titer-dependent response during differentiation to human derivatives not expressing OCT4. Our findings demonstrate that the OCT4-short response element is active in pluripotency and this activity is in high correlation with transgene expression in vitro, and the OCT4-short response element is inactivated when pluripotent cells differentiate. These studies demonstrate that this shortened OCT4 regulatory element is functional and may be useful as part of an optimized safety component in a site-specific gene transferring system that could be used as an efficient and clinically applicable safety platform for gene transfer in cellular therapeutics. PMID:27500178

  2. A facile method for fabrication of responsive micropatterned surfaces

    NASA Astrophysics Data System (ADS)

    Demiryürek, Rıdvan; Kassim Ali, Mariamu; Ozaydin Ince, Gozde

    2014-09-01

    Responsive micropatterned surfaces are fabricated using a facile, one-step method that allows for the separate control of topography and surface chemistry. Temperature responsive poly(N-isopropylacrylamide) (pNIPAAm), and amphiphilic poly(hydroxyethyl methacrylate-co-perfluorodecylacrylate) (p(HEMA-co-PFA)) polymer thin films are deposited on prestrained polydimethylsiloxane (PDMS) substrates using the initiated chemical vapor deposition (iCVD) technique. Subsequent release of the strain results in the formation of periodic wrinkle structures on the surface of polymer thin films. The iCVD technique allows control of the chemical composition while preserving the functional groups of the polymers intact. Surface topography is controlled separately by tuning elastic modulus of the polymer coatings and substrates. Highly ordered, well-defined wrinkle structures are obtained on pNIPAAm surfaces whereas wrinkles on the amphiphilic surfaces are less ordered due to the difference in elastic moduli of the polymers. Furthermore, process temperature is observed to have detrimental effects on the ordering of the wrinkles.

  3. Responses of Trace Elements to Aerobic Maximal Exercise in Elite Sportsmen

    PubMed Central

    OTAĞ, Aynur; HAZAR, Muhsin; OTAĞ, İlhan; Gürkan, Alper Cenk; Okan, İlyas

    2014-01-01

    Trace elements are chemical elements needed in minute quantities for the proper growth, development, and physiology of the organism. In biochemistry, a trace element is also referred to as a micronutrient. Trace elements, such as nickel, cadmium, aluminum, silver, chromium, molybdenum, germanium, tin, titanium, tungsten, scandium, are found naturally in the environment and human exposure derives from a variety of sources, including air, drinking water and food. The Purpose of this study was investigated the effect of aerobic maximal intensity endurance exercise on serum trace elements as well-trained individuals of 28 wrestlers (age (year) 19.64±1.13, weight (Kg) 70.07 ± 15.69, height (cm) 176.97 ± 6.69) during and after a 2000 meter Ergometer test protocol was used to perform aerobic (75 %) maximal endurance exercise. Trace element serum levels were analyzed from blood samples taken before, immediately after and one hour after the exercise. While an increase was detected in Chromium (Cr), Nickel (Ni), Molybdenum (Mo) and Titanium (Ti) serum levels immediately after the exercise, a decrease was detected in Aluminum (Al), Scandium (Sc) and Tungsten (W) serum levels. Except for aluminum, the trace elements we worked on showed statistically meaningful responses (P<0.05 and P<0.001). According to the responses of trace elements to the exercise showed us the selection and application of the convenient sport is important not only in terms of sportsman performance but also in terms of future healthy life plans and clinically. PMID:24762350

  4. Experimental measurement of tympanic membrane response for finite element model validation of a human middle ear.

    PubMed

    Ahn, Tae-Soo; Baek, Moo-Jin; Lee, Dooho

    2013-01-01

    The middle ear consists of a tympanic membrane, ligaments, tendons, and three ossicles. An important function of the tympanic membrane is to deliver exterior sound stimulus to the ossicles and inner ear. In this study, the responses of the tympanic membrane in a human ear were measured and compared with those of a finite element model of the middle ear. A laser Doppler vibrometer (LDV) was used to measure the dynamic responses of the tympanic membrane, which had the measurement point on the cone of light of the tympanic membrane. The measured subjects were five Korean male adults and a cadaver. The tympanic membranes were stimulated using pure-tone sine waves at 18 center frequencies of one-third octave band over a frequency range of 200 Hz ~10 kHz with 60 and 80 dB sound pressure levels. The measured responses were converted into the umbo displacement transfer function (UDTF) with a linearity assumption. The measured UDTFs were compared with the calculated UDTFs using a finite element model for the Korean human middle ear. The finite element model of the middle ear consists of three ossicles, a tympanic membrane, ligaments, and tendons. In the finite element model, the umbo displacements were calculated under a unit sound pressure on the tympanic membrane. The UDTF of the finite element model exhibited good agreement with that of the experimental one in low frequency range, whereas in higher frequency band, the two response functions deviated from each other, which demonstrates that the finite element model should be updated with more accurate material properties and/or a frequency dependent material model.

  5. Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device

    NASA Astrophysics Data System (ADS)

    Mohibul Kabir, K. M.; Matthews, Glenn I.; Sabri, Ylias M.; Russo, Salvy P.; Ippolito, Samuel J.; Bhargava, Suresh K.

    2016-03-01

    Accurate analysis of surface acoustic wave (SAW) devices is highly important due to their use in ever-growing applications in electronics, telecommunication and chemical sensing. In this study, a novel approach for analyzing the SAW devices was developed based on a series of two-dimensional finite element method (FEM) simulations, which has been experimentally verified. It was found that the frequency response of the two SAW device structures, each having slightly different bandwidth and center lobe characteristics, can be successfully obtained utilizing the current density of the electrodes via FEM simulations. The two SAW structures were based on XY Lithium Niobate (LiNbO3) substrates and had two and four electrode finger pairs in both of their interdigital transducers, respectively. Later, SAW devices were fabricated in accordance with the simulated models and their measured frequency responses were found to correlate well with the obtained simulations results. The results indicated that better match between calculated and measured frequency response can be obtained when one of the input electrode finger pairs was set at zero volts and all the current density components were taken into account when calculating the frequency response of the simulated SAW device structures.

  6. Surface element-mapping of three dimensional structures by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Beresko, Christian; Kohns, Peter; Ankerhold, Georg

    2014-09-01

    During lateral mapping with laser-induced breakdown spectroscopy (LIBS) the focal position of the plasma-generating laser needs to be kept stable on the sample surface area to be probed. Therefore, three-dimensional structures like edged surfaces require a permanent re-focusing. We describe a new auto-focusing technique to perform surface elemental mapping with LIBS by correcting the focusing lens-to-sample distance using a direct monitoring of the LIBS signal intensity. This method allows the scanning of surfaces with strong height fluctuations of several millimeters without the need of any additional devices. The auto-focusing method is valuable for LIBS applications made on complex-shaped samples or simply to improve the measurement reproducibility. Applications are LIBS analyses of samples exhibiting drill holes or steep edges. Our procedure does not need a constant focal plane and follows the topographic profile of the sample surface. Impurities and material inclusions are well detected. From the topographic information additionally obtained, a three-dimensional image of the sample can be deduced. Depth resolution is limited by the Rayleigh range of the LIBS laser light. The method is best suited for low energy laser pulses with high repetition rate and infrared emission.

  7. Surface myomechanical responses recorded on a scanner galvanometer.

    PubMed

    Rafolt, D; Gallasch, E

    2002-09-01

    A moving magnet galvanometer equipped with lever and indentor was evaluated for mechanomyography (MMG). First, the precision of the galvanometer was tested on a piezo-electric disc actuator. Using a 50 mm lever, synthesised micromotions with an amplitude of 1 microm could be detected (noise level < 0.2 microm) at static indentation forces ranging from 0.1 to 2 N. Then the galvanometer was mounted on an isometric ankle dynamometer to sense calf-muscle responses (N = 6). In the first protocol, twitch contractions were elicited by electrical stimulation while the indentation force was increased. Twitch amplitudes, twitch contraction times and twitch half-relaxation times were analysed from the surface and contraction responses. With indentation force (0.1-0.5 N), the amplitude of the surface responses increased (+61%), contraction and half-relaxation times, however, were not influenced. The mean twitch contraction time from the surface responses (60 +/- 11 ms) was shorter than that from the contraction responses (115 +/- 7 ms), indicating more fast-contracting fibres under the indented area. In the second protocol, voluntary target contractions were produced, and the surface responses were simultaneously recorded on an accelerometer. After double differentiation of the galvanometer signal, both acceleration MMGs showed a high coincidence in the time and frequency domains. With an indentation force of 2 N applied on the accelerometer, the signal amplitude (-10%) and the mean frequency (-19%) decreased. A specific application of this galvanometer-dynamometer test system is the assessment of regeneration processes in paraplegics with long-term denervated muscles.

  8. Surface myomechanical responses recorded on a scanner galvanometer.

    PubMed

    Rafolt, D; Gallasch, E

    2002-09-01

    A moving magnet galvanometer equipped with lever and indentor was evaluated for mechanomyography (MMG). First, the precision of the galvanometer was tested on a piezo-electric disc actuator. Using a 50 mm lever, synthesised micromotions with an amplitude of 1 microm could be detected (noise level < 0.2 microm) at static indentation forces ranging from 0.1 to 2 N. Then the galvanometer was mounted on an isometric ankle dynamometer to sense calf-muscle responses (N = 6). In the first protocol, twitch contractions were elicited by electrical stimulation while the indentation force was increased. Twitch amplitudes, twitch contraction times and twitch half-relaxation times were analysed from the surface and contraction responses. With indentation force (0.1-0.5 N), the amplitude of the surface responses increased (+61%), contraction and half-relaxation times, however, were not influenced. The mean twitch contraction time from the surface responses (60 +/- 11 ms) was shorter than that from the contraction responses (115 +/- 7 ms), indicating more fast-contracting fibres under the indented area. In the second protocol, voluntary target contractions were produced, and the surface responses were simultaneously recorded on an accelerometer. After double differentiation of the galvanometer signal, both acceleration MMGs showed a high coincidence in the time and frequency domains. With an indentation force of 2 N applied on the accelerometer, the signal amplitude (-10%) and the mean frequency (-19%) decreased. A specific application of this galvanometer-dynamometer test system is the assessment of regeneration processes in paraplegics with long-term denervated muscles. PMID:12452422

  9. Boundary element simulation of surface waves on a deformed half-space

    NASA Astrophysics Data System (ADS)

    Litvinchuk, S. Yu.; Belov, A. A.; Markov, I. P.; Ipatov, A. A.; Petrov, A. N.

    2015-11-01

    Homogeneous and two-layer half-spaces consisting of an anisotropic elastic, isotropic viscoelastic, or poroelastic material are considered. The Kelvin-Voigt model and the model with the Abel kernel are used as models of the viscoelastic material; the poroelastic material is studied within the framework of the model of the compressible Biot material. The case where the half-space contains a cavity is also considered. Propagation of surface waves is studied by the boundary element method. The numerical solution involves the method of collocations for a regularized boundary integral equation.

  10. Transformation of the human ovarian surface epithelium with genetically defined elements.

    PubMed

    Shan, Weiwei; Liu, Jinsong

    2013-01-01

    Success in in vitro transformation of primary cells from the human ovarian surface epithelium (OSE) has provided significant insight to the study of human ovarian cancer. Here, we describe the method used to immortalize and transform OSE by serial introduction of viral and nonviral genetic elements as well as to test the tumorigenicity of hence established cell lines in appropriate animal models. Successful transformation of OSE cells in the laboratory is of critical significance to the study of ovarian cancer. It not only allows for testing the roles of numerous potential oncogenes in initiating and promoting human ovarian cancer but provides a convenient tool to comprehensively dissect ovarian tumorigenesis in the laboratory.

  11. Interactive computer graphic surface modeling of three-dimensional solid domains for boundary element analysis

    NASA Technical Reports Server (NTRS)

    Perucchio, R.; Ingraffea, A. R.

    1984-01-01

    The establishment of the boundary element method (BEM) as a valid tool for solving problems in structural mechanics and in other fields of applied physics is discussed. The development of an integrated interactive computer graphic system for the application of the BEM to three dimensional problems in elastostatics is described. The integration of interactive computer graphic techniques and the BEM takes place at the preprocessing and postprocessing stages of the analysis process, when, respectively, the data base is generated and the results are interpreted. The interactive computer graphic modeling techniques used for generating and discretizing the boundary surfaces of a solid domain are outlined.

  12. Quantifying Surface Kinetic Fractionations for Isotopes and Trace Elements in Calcite Precipitated from Aqueous Solution

    NASA Astrophysics Data System (ADS)

    DePaolo, D. J.; Nielsen, L. C.; Hofmann, A. E.; DeYoreo, J.; Gagnon, A. C.; Watkins, J. M.; Ryerson, F. J.; Brown, S. T.

    2011-12-01

    The isotopic ratios and trace element concentrations in calcite and other carbonate minerals form the basis for several paleoenvironmental indicators that are relied upon to reconstruct past Earth climates and ocean processes. Most of these carbonate minerals form at low temperatures (0 to 30C) and consequently are unlikely to have precipitated from aqueous solutions at equilibrium. The non-equilibrium nature of the precipitation process is well illustrated by the experimentally demonstrated precipitation rate-dependence of parameters such as the Ca and O isotopic composition, and the Sr, Mg, and Mn concentrations of calcite. We have been focused on understanding how to predict the magnitude and controls on these kinetic effects using a general transition-state theory approach, as well as models of ion-by-ion growth, molecular dynamics simulations of the desolvation step required for addition of cations to a mineral surface, and further experiments that involve carefully controlled solution compositions and crystal growth rates. Although models have been proposed that invoke diffusion as the primary control on the non-equilibrium aspects of calcite precipitation, it is relatively easy to show that diffusion is not likely to be the primary controlling process. We have focused on understanding the kinetic effects operating at and near the mineral surface, which are undeniably present and important, and appear to be of the correct magnitude and direction to account for observations in both laboratory and natural calcites. The approach we are using is also applicable to higher temperature aqueous precipitation. There are indications from Ca isotopes that similar surface kinetic effects occur at temperatures of 300 to 400C. Kinetic isotope and trace element effects are critically dependent on molecular exchange rates between the mineral surface and the aqueous solution, and the ratio of these rates to the net crystal growth rate. The challenge is to predict and

  13. Intelligent Detection of Cracks in Metallic Surfaces Using a Waveguide Sensor Loaded with Metamaterial Elements

    PubMed Central

    Ali, Abdulbaset; Hu, Bing; Ramahi, Omar M.

    2015-01-01

    This work presents a real-life experiment implementing an artificial intelligence model for detecting sub-millimeter cracks in metallic surfaces on a dataset obtained from a waveguide sensor loaded with metamaterial elements. Crack detection using microwave sensors is typically based on human observation of change in the sensor's signal (pattern) depicted on a high-resolution screen of the test equipment. However, as demonstrated in this work, implementing artificial intelligence to classify cracked from non-cracked surfaces has appreciable impacts in terms of sensing sensitivity, cost, and automation. Furthermore, applying artificial intelligence for post-processing the data collected from microwave sensors is a cornerstone for handheld test equipment that can outperform rack equipment with large screens and sophisticated plotting features. The proposed method was tested on a metallic plate with different cracks, and the experimental results showed good crack classification accuracy rates. PMID:25988871

  14. Tolerancing of single point diamond turned diffractive optical elements and optical surfaces

    NASA Astrophysics Data System (ADS)

    Bittner, R. F.

    2007-10-01

    Single point diamond turning has an increasing importance with the production of the surfaces for different optical systems such as infrared systems, prototype production of mobile phone cameras or head mounted displays with plastic lenses or master manufacturing for the injection moulding of plastic lenses for mass products. Tolerances which occur during single point diamond turning of aspheric surfaces and diffractive elements or during polar coordinate laser plotting of Computer-generated holograms will be treated. In both cases we expect similar tolerances, because the work piece is rotated in both diamond turning and laser plotting. The purpose is to understand the typical tolerances and to simulate their influence to the aberrations in the optical system.

  15. The effect of loading time on flexible pavement dynamic response: a finite element analysis

    NASA Astrophysics Data System (ADS)

    Yin, Hao; Solaimanian, Mansour; Kumar, Tanmay; Stoffels, Shelley

    2007-12-01

    Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

  16. Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.

    PubMed

    Liu, Jiansheng; Lu, Yanyan

    2014-04-16

    A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

  17. Optical response of reconstructed GaP(001) surfaces

    NASA Astrophysics Data System (ADS)

    Zorn, M.; Junno, B.; Trepk, T.; Bose, S.; Samuelson, L.; Zettler, J.-T.; Richter, W.

    1999-10-01

    GaP(001) surfaces were found to reconstruct with (2×1) or (2×4) symmetry under surface conditions corresponding to a high or low V/III surface stoichiometry ratio, respectively. These surface reconstructions, identified by reflection high-energy electron diffraction, have been prepared in a chemical beam epitaxy (CBE) system by varying the sample temperature. Reflectance anisotropy spectra (RAS) of these surfaces have been taken under both CBE and metal-organic vapor phase epitaxy conditions. Three different phases of (2×4) symmetry have been distinguished according to their characteristic RAS response in agreement with recent theoretical predictions [A.M. Frisch, W.G. Schmidt, J. Bernholc, M. Pristovsek, N. Esser, and W. Richter, Phys. Rev B 60, 2488 (1999)]. For the (2×1) reconstruction a line-shape analysis of the RAS signatures was performed and their temperature shifts have been compared to the respective shifts of the bulk critical points. These experiments indicate the GaP(001)-(2×1) surface dielectric anisotropy originating from transitions between bulk states modified by the surface due to band-folding effects and anisotropic shifts of the E1 and E'0 critical point energies.

  18. Investigation of the surface generation mechanism of mechanical polishing engineering ceramics using discrete element method

    NASA Astrophysics Data System (ADS)

    Han, Xuesong

    2014-09-01

    Machining technology about ceramics has been developed very fast over recent years due to the growing industrial demand of higher machining accuracy and better surface quality of ceramic elements, while the nature of hard and brittle ceramics makes it difficult to acquire damage-free and ultra-smooth surface. Ceramic bulk can be treated as an assemblage of discrete particles bonded together randomly as the micro-structure of ceramics consists of crystal particles and pores, and the inter-granular fracture of the ceramics can be naturally represented by the separation of particles due to breakage of bonds. Discrete element method (DEM) provides a promising approach for constructing an effective model to describe the tool-workpiece interaction and can serve as a predicting simulation tool in analyzing the complicated surface generation mechanism and is employed in this research to simulate the mechanical polishing process of ceramics and surface integrity. In this work, a densely packed particle assembly system of the polycrystalline Si3N4 has been generated using bonded-particle model to represent the ceramic workpiece numerically. The simulation results justify that the common critical depth of cut cannot be used as the effective parameters for evaluating brittle to ductile transformation in ceramic polishing process. Therefore, a generalized criterion of defining the range of ductile regime machining has been developed based on the numerical results. Furthermore, different distribution of pressure chain is observed with different depth of cut which ought to have intense relationship with special structure of ceramics. This study also justified the advantage of DEM model in its capability of revealing the mechanical behaviors of ceramics at micro-scale.

  19. Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, Jim J.

    1992-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. These discharge features, which include 50 micron diameter areas where the aluminum top layer has been vaporized, facilitate the location of the impacts. The high purity Al-SiO2-Si substrates allow detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) is used to create two-dimensional elemental ion intensity maps of micro-particle impact sites on the IDE sensors. The element intensities in the central craters of the impacts are corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results are used to classify the particles' origins as 'manmade', 'natural' or 'indeterminate'. The last classification results from the presence of too little impactor residue (a frequent occurrence on leading edge impacts), analytical interference from high background contamination, the lack of information on silicon residue, the limited usefulness of data on aluminum in the central craters, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. A

  20. Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics

    PubMed Central

    Larsson Wexell, C.; Thomsen, P.; Aronsson, B.-O.; Tengvall, P.; Rodahl, M.; Lausmaa, J.; Kasemo, B.; Ericson, L. E.

    2013-01-01

    In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography. PMID:24174936

  1. The Indirect Boundary Element Method (IBEM) for Seismic Response of Topographical Irregularities in Layered Media

    NASA Astrophysics Data System (ADS)

    Contreras Zazueta, M. A.; Perton, M.; Sanchez-Sesma, F. J.; Sánchez-Alvaro, E.

    2013-12-01

    The seismic hazard assessment of extended developments, such as a dam, a bridge or a pipeline, needs the strong ground motion simulation taking into account the effects of surface geology. In many cases the incoming wave field can be obtained from attenuation relations or simulations for layered media using Discrete Wave Number (DWN). Sometimes there is a need to include in simulations the seismic source as well. A number of methods to solve these problems have been developed. Among them the Finite Element and Finite Difference Methods (FEM and FDM) are generally preferred because of the facility of use. Nevertheless, the analysis of realistic dynamic loading induced by earthquakes requires a thinner mesh of the entire domain to consider high frequencies. Consequently this may imply a high computational cost. The Indirect Boundary Element Method (IBEM) can also be employed. Here it is used to study the response of a site to historical seismic activity. This method is particularly suited to model wave propagation through wide areas as it requires only the meshing of boundaries. Moreover, it is well suited to represent finely the diffraction that can occur on a fault. However, the IBEM has been applied mainly to simple geometrical configurations. In this communication significant refinements of the formulation are presented. Using IBEM we can simulate wave propagation in complex geometrical configurations such as a stratified medium crossed by thin faults or having a complex topography. Two main developments are here described; one integrates the DWN method inside the IBEM in order to represent the Green's functions of stratified media with relatively low computational cost but assuming unbounded parallel flat layers, and the other is the extension of IBEM to deal with multi-regions in contact which allows more versatility with a higher computational cost compared to the first one but still minor to an equivalent FEM formulation. The two approaches are fully

  2. Using Response Surface Methods to Correlate the Modal Test of an Inflatable Test Article

    NASA Technical Reports Server (NTRS)

    Gupta, Anju

    2013-01-01

    This paper presents a practical application of response surface methods (RSM) to correlate a finite element model of a structural modal test. The test article is a quasi-cylindrical inflatable structure which primarily consists of a fabric weave, with an internal bladder and metallic bulkheads on either end. To mitigate model size, the fabric weave was simplified by representing it with shell elements. The task at hand is to represent the material behavior of the weave. The success of the model correlation is measured by comparing the four major modal frequencies of the analysis model to the four major modal frequencies of the test article. Given that only individual strap material properties were provided and material properties of the overall weave were not available, defining the material properties of the finite element model became very complex. First it was necessary to determine which material properties (modulus of elasticity in the hoop and longitudinal directions, shear modulus, Poisson's ratio, etc.) affected the modal frequencies. Then a Latin Hypercube of the parameter space was created to form an efficiently distributed finite case set. Each case was then analyzed with the results input into RSM. In the resulting response surface it was possible to see how each material parameter affected the modal frequencies of the analysis model. If the modal frequencies of the analysis model and its corresponding parameters match the test with acceptable accuracy, it can be said that the model correlation is successful.

  3. The MYC 3' Wnt-Responsive Element Drives Oncogenic MYC Expression in Human Colorectal Cancer Cells.

    PubMed

    Rennoll, Sherri A; Eshelman, Melanie A; Raup-Konsavage, Wesley M; Kawasawa, Yuka Imamura; Yochum, Gregory S

    2016-01-01

    Mutations in components of the Wnt/β-catenin signaling pathway drive colorectal cancer (CRC) by deregulating expression of downstream target genes including the c-MYC proto-oncogene (MYC). The critical regulatory DNA enhancer elements that control oncogenic MYC expression in CRC have yet to be fully elucidated. In previous reports, we correlated T-cell factor (TCF) and β-catenin binding to the MYC 3' Wnt responsive DNA element (MYC 3' WRE) with MYC expression in HCT116 cells. Here we used CRISPR/Cas9 to determine whether this element is a critical driver of MYC. We isolated a clonal population of cells that contained a deletion of a single TCF binding element (TBE) within the MYC 3' WRE. This deletion reduced TCF/β-catenin binding to this regulatory element and decreased MYC expression. Using RNA-Seq analysis, we found altered expression of genes that regulate metabolic processes, many of which are known MYC target genes. We found that 3' WRE-Mut cells displayed a reduced proliferative capacity, diminished clonogenic growth, and a decreased potential to form tumors in vivo. These findings indicate that the MYC 3' WRE is a critical driver of oncogenic MYC expression and suggest that this element may serve as a therapeutic target for CRC. PMID:27223305

  4. Endothelial responses of magnesium and other alloying elements in magnesium-based stent materials

    PubMed Central

    Zhao, Nan; Zhu, Donghui

    2016-01-01

    Biodegradable tailored magnesium (Mg) alloys are some of the most promising scaffolds for cardiovascular stents. During the course of degradation after implantation, all the alloying elements in the scaffold will be released to the surrounding vascular tissues. However, fundamental questions regarding the toxicity of alloying elements towards vascular cells, the maximum amount of each element that could be used in alloy design, or how each of the alloying elements affects vascular cellular activity and gene expression, are still not fully answered. This work systematically addressed these questions by revealing how application of different alloying elements commonly used in Mg stent materials influences several indices of human endothelial cell health, i.e., viability, proliferations, cytoskeletal reorganizations, migration, and the gene expression profile. The overall cell viability and proliferation showed a decreasing trend with increasing concentrations of the ions, and the half maximal effective concentrations (EC50) for each element were determined. When applied at a low concentration of around 10 mM, Mg had no adverse effects but improved cell proliferation and migration instead. Mg ions also altered endothelial gene expression significantly in a dose dependent manner. Most of the changed genes are related to angiogenesis and the cell adhesion signaling pathways. Findings from this work provide useful information on maximum safe doses of these ions for endothelial cells, endothelial responses towards these metal ions, and some guidance for future Mg stent design. PMID:25363018

  5. An extended validation of the last generation of particle finite element method for free surface flows

    NASA Astrophysics Data System (ADS)

    Gimenez, Juan M.; González, Leo M.

    2015-03-01

    In this paper, a new generation of the particle method known as Particle Finite Element Method (PFEM), which combines convective particle movement and a fixed mesh resolution, is applied to free surface flows. This interesting variant, previously described in the literature as PFEM-2, is able to use larger time steps when compared to other similar numerical tools which implies shorter computational times while maintaining the accuracy of the computation. PFEM-2 has already been extended to free surface problems, being the main topic of this paper a deep validation of this methodology for a wider range of flows. To accomplish this task, different improved versions of discontinuous and continuous enriched basis functions for the pressure field have been developed to capture the free surface dynamics without artificial diffusion or undesired numerical effects when different density ratios are involved. A collection of problems has been carefully selected such that a wide variety of Froude numbers, density ratios and dominant dissipative cases are reported with the intention of presenting a general methodology, not restricted to a particular range of parameters, and capable of using large time-steps. The results of the different free-surface problems solved, which include: Rayleigh-Taylor instability, sloshing problems, viscous standing waves and the dam break problem, are compared to well validated numerical alternatives or experimental measurements obtaining accurate approximations for such complex flows.

  6. Improvements to a Response Surface Thermal Model for Orion

    NASA Technical Reports Server (NTRS)

    Miller, Stephen W.; Walker, William Q.

    2011-01-01

    A study was performed to determine if a Design of Experiments (DOE)/Response Surface Methodology could be applied to on-orbit thermal analysis and produce a set of Response Surface Equations (RSE) that predict Orion vehicle temperatures within 10 F. The study used the Orion Outer Mold Line model. Five separate factors were identified for study: yaw, pitch, roll, beta angle, and the environmental parameters. Twenty-three external Orion components were selected and their minimum and maximum temperatures captured over a period of two orbits. Thus, there are 46 responses. A DOE case matrix of 145 runs was developed. The data from these cases were analyzed to produce a fifth order RSE for each of the temperature responses. For the 145 cases in the DOE matrix, the agreement between the engineering data and the RSE predictions was encouraging with 40 of the 46 RSEs predicting temperatures within the goal band. However, the verification cases showed most responses did not meet the 10 F goal. After reframing the focus of the study to better align the RSE development with the purposes of the model, a set of RSEs for both the minimum and maximum radiator temperatures was produced which predicted the engineering model output within +/-4 F. Therefore, with the correct application of the DOE/RSE methodology, RSEs can be developed that provide analysts a fast and easy way to screen large numbers of environments and assess proposed changes to the RSE factors.

  7. Partial-slip frictional response of rough surfaces

    PubMed Central

    Paggi, Marco; Pohrt, Roman; Popov, Valentin L.

    2014-01-01

    If two elastic bodies with rough surfaces are first pressed against each other and then loaded tangentially, sliding will occur at the boundary of the contact area while the inner parts may still stick. With increasing tangential force, the sliding parts will expand while the sticking parts shrink and finally vanish. In this paper, we study the fractions of the contact area, tangential force and tangential stiffness, associated with the sticking portion of the contact area, as a function of the total applied tangential force up to the onset of full sliding. For the numerical analysis randomly rough, fractal surfaces are used, with the Hurst exponent H ranging from 0.1 to 0.9. Numerical simulations by boundary element method are compared with an analytical analysis in the framework of the Greenwood and Williamson (GW) model. In both cases, a universal linear dependency between the real contact area fraction in stick condition and the applied tangential force is found, regardless of the Hurst exponent of the rough surfaces. Regarding the dependence of the differential tangential stiffness on the tangential force, a linear relation is found in the GW case. For randomly rough surfaces, a nonlinear relation depending on H is derived. PMID:24898988

  8. Elemental responses to subduction-zone metamorphism: Constraints from the North Qilian Mountain, NW China

    NASA Astrophysics Data System (ADS)

    Xiao, Yuanyuan; Niu, Yaoling; Song, Shuguang; Davidson, Jon; Liu, Xiaoming

    2013-02-01

    Subduction zone metamorphism (SZM) and behaviors of chemical elements in response to this process are important for both arc magmatism and mantle compositional heterogeneity. In this paper, we report the results of our petrographic and geochemical studies on blueschist and eclogite facies rocks of sedimentary and basaltic protoliths from two metamorphic sub-belts with different metamorphic histories in the North Qilian Mountain, Northwest China. The protolith of low-grade blueschists is basaltic in composition and is most likely produced in a back-arc setting, while the protoliths of high-grade blueschists/eclogites geochemically resemble the present-day normal and enriched mid-oceanic ridge basalts plus some volcanic arc rocks. The meta-sedimentary rocks, including meta-graywacke, meta-pelite, meta-chert and marble, show geochemical similarity to global oceanic (subducted) sediments. Assuming that high field strength elements (HFSEs) are relatively immobile, the correlated variations of rare earth elements (REEs) and Th with HFSEs suggest that all these elements are probably also immobile, whereas Pb and Sr are mobile in rocks of both basaltic and sedimentary protoliths during SZM. Ba, Cs and Rb are immobile in rocks of sedimentary protoliths and mobile in rocks of basaltic protolith. The apparent mobility of U in rocks of basaltic protolith may be inherited from seafloor alterations rather than caused by SZM. On the basis of in situ mineral compositional analysis (both major and trace elements), the most significant trace element storage minerals in these subduction-zone metamorphic rocks are: lawsonite, pumpellyite, apatite, garnet and epidote group minerals for REEs, white micas (both phengite and paragonite) for large ion lithophile elements, rutile and titanite for HFSEs. The presence and stability of these minerals exert the primary controls on the geochemical behaviors of most of these elements during SZM. The immobility of REEs, Th and U owing to their

  9. Combining Noise Factors and Process Parameters in a Response Surface

    SciTech Connect

    Wyckoff, J.J.

    1998-03-19

    This presentation covers the strategy and analysis of an experiment to characterize a gas tungsten arc welding process. The experiment combined four uncontrolled noise factors and four controlled process parameters. A nontraditional response surface design was employed. Multiple responses were modeled. Optimal settings for the process parameters to successfully weld the widest range of the pertinent product features were identified. Thus, the process was made ''robust'' against ''noise'' factors. Comparisons are made between the experimental and analytical approach taken versus the Taguchi style of experimentation and analysis. This comparison is mainly done with respect to the information gained, such as product design criteria, incoming material specifications, and process adjustments for nonconforming material.

  10. Global Geochemical Variation on the Lunar Surface: A Three-Element Approach

    NASA Technical Reports Server (NTRS)

    Thomsen, D. R.; Lawrence, D. J.; Vaniman, D.; Feldman, W. C.; Elphic, R. C.; Barraclough, B. L.; Maurice, S.; Lucey, P. G.; Binder, A. B.

    1999-01-01

    We present a method for displaying the relative abundances of three important elements (Th, Fe, and Ti) on the same map projection of the lunar surface. Using Th-, Fe-, and Ti-elemental abundances from orbital geochemical data and assigning each element a primary color, a false-color map of the lunar surface was created. This approach is similar to the ternary diagram approach presented by Davis and Spudis with some important differences, discussed later. For the present maps, Th abundances were measured by the Lunar Prospector (LP) Gamma-Ray Spectrometer(GRS).The new LPGRS low-altitude dataset was used in this analysis. Iron and Ti weight percentages were based on Clementine spectral reflectance data smoothed to the LP low altitude footprint. This method of presentation was designed to aid in the location and recognition of three principal lunar compositions: ferroan anorthosite (FAN), mare basalts (MB), and the Mg suite/ KREEP-rich rocks on the lunar surface, with special emphasis on the highlands and specific impact basins. In addition to the recognition of these endmember rock compositions, this method is an attempt to examine the relationship between elemental compositions that do not conform readily to previously accepted or observed endmember rocks in various specific regions of interest, including eastern highlands regions centered on 150 deg longitude, and a northern highlands Th-rich region observed. The LP low-altitude data has full width at half-maximum spatial resolution of about 40 km. The Clementine spectral reflectance datasets were adapted using an equal-area, gaussian smoothing routine to this footprint. In addition, these datasets, reported in weight percent of FeO and of Ti02, were adjusted to Fe and Ti weight percentages. Each dataset was then assigned one of the three primary colors: blue for Th, red for Fe, and green for Ti. For each element, the data range was normalized to represent the ratio of each point to the maximum in the dataset. (To

  11. Transport of dissolved trace elements in surface runoff and leachate from a coastal plain soil after poultry litter application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The application of poultry (Gallus gallus domesticus) litter to agricultural soils may exacerbate losses of trace elements in runoff water, an emerging concern to water quality. We evaluated trace elements (arsenic, cadmium, copper, lead, manganese, mercury, selenium and zinc) in surface runoff and ...

  12. Spatial Patterns of Radiative Forcing and Surface Temperature Response

    NASA Astrophysics Data System (ADS)

    Shindell, D. T.

    2014-12-01

    Examination of radiative forcing (RF), a key measure of changes in the energy balance of the Earth, facilitates understanding of the role of various drivers of climate change. For short-lived compounds, the RF can be highly inhomogeneous geographically. The relationship between the spatial patterns of RF and climate response is poorly characterized, however. Here we examine the relationship between RF and surface temperature response in the latest generation of climate models. We find that the geographic distribution of historical changes in aerosol and ozone RF strongly influences the response, leading to substantial regional differences with respect to the response to quasi-uniform well-mixed greenhouse gases (WMGHG). In particular, the response in the Northern Hemisphere (NH) extratropics and tropics follows the forcing in those regions fairly closely. There is a stronger global sensitivity to historical aerosol plus ozone RF than to WMGHG RF with equivalent global mean value, as noted previously [D T Shindell, 2014] and a stronger response in much of the NH extratropics, especially in and downwind of industrialized areas. The enhanced response is shown to be particularly large over land plus polar ocean areas, where transient response occurs more rapidly and strong snow and ice albedo feedbacks operate. This response is not attributable to greater forcing over those regions, but rather appears to reflect a broad sensitivity of NH extratropical land areas to NH extratropical forcing. The models show substantial diversity in the enhancement of land+polar ocean response to aerosols plus ozone relative to WMGHG, and for ocean response some models show reduced sensitivity to aerosols plus ozone (though the multi-model mean shows an enhancement), suggesting that different representations of land and ocean adjustment timescales and regional heat transport contribute greatly to the differences in response to inhomogeneous forcing. In addition, areas with greatest

  13. Analysis of discontinuities across thin inhomogeneities, groundwater/surface water interactions in river networks, and circulation about slender bodies using slit elements in the Analytic Element Method.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Groundwater and surface water contain interfaces across which hydrologic functions are discontinuous. Thin elements with high hydraulic conductivity in a porous media focus groundwater, which flows through such inhomogeneities and causes an abrupt change in stream function across their interfaces, a...

  14. Creating diversified response profiles from a single quenchometric sensor element by using phase-resolved luminescence.

    PubMed

    Tehan, Elizabeth C; Bukowski, Rachel M; Chodavarapu, Vamsy P; Titus, Albert H; Cartwright, Alexander N; Bright, Frank V

    2015-01-05

    We report a new strategy for generating a continuum of response profiles from a single luminescence-based sensor element by using phase-resolved detection. This strategy yields reliable responses that depend in a predictable manner on changes in the luminescent reporter lifetime in the presence of the target analyte, the excitation modulation frequency, and the detector (lock-in amplifier) phase angle. In the traditional steady-state mode, the sensor that we evaluate exhibits a linear, positive going response to changes in the target analyte concentration. Under phase-resolved conditions the analyte-dependent response profiles: (i) can become highly non-linear; (ii) yield negative going responses; (iii) can be biphasic; and (iv) can exhibit super sensitivity (e.g., sensitivities up to 300 fold greater in comparison to steady-state conditions).

  15. Creating Diversified Response Profiles from a Single Quenchometric Sensor Element by Using Phase-Resolved Luminescence

    PubMed Central

    Tehan, Elizabeth C.; Bukowski, Rachel M.; Chodavarapu, Vamsy P.; Titus, Albert H.; Cartwright, Alexander N.; Bright, Frank V.

    2015-01-01

    We report a new strategy for generating a continuum of response profiles from a single luminescence-based sensor element by using phase-resolved detection. This strategy yields reliable responses that depend in a predictable manner on changes in the luminescent reporter lifetime in the presence of the target analyte, the excitation modulation frequency, and the detector (lock-in amplifier) phase angle. In the traditional steady-state mode, the sensor that we evaluate exhibits a linear, positive going response to changes in the target analyte concentration. Under phase-resolved conditions the analyte-dependent response profiles: (i) can become highly non-linear; (ii) yield negative going responses; (iii) can be biphasic; and (iv) can exhibit super sensitivity (e.g., sensitivities up to 300 fold greater in comparison to steady-state conditions). PMID:25569752

  16. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  17. Emission-dominated gas exchange of elemental mercury vapor over natural surfaces in China

    NASA Astrophysics Data System (ADS)

    Wang, Xun; Lin, Che-Jen; Yuan, Wei; Sommar, Jonas; Zhu, Wei; Feng, Xinbin

    2016-09-01

    Mercury (Hg) emission from natural surfaces plays an important role in global Hg cycling. The present estimate of global natural emission has large uncertainty and remains unverified against field data, particularly for terrestrial surfaces. In this study, a mechanistic model is developed for estimating the emission of elemental mercury vapor (Hg0) from natural surfaces in China. The development implements recent advancements in the understanding of air-soil and air-foliage exchange of Hg0 and redox chemistry in soil and on surfaces, incorporates the effects of soil characteristics and land use changes by agricultural activities, and is examined through a systematic set of sensitivity simulations. Using the model, the net exchange of Hg0 between the atmosphere and natural surfaces of mainland China is estimated to be 465.1 Mg yr-1, including 565.5 Mg yr-1 from soil surfaces, 9.0 Mg yr-1 from water bodies, and -100.4 Mg yr-1 from vegetation. The air-surface exchange is strongly dependent on the land use and meteorology, with 9 % of net emission from forest ecosystems; 50 % from shrubland, savanna, and grassland; 33 % from cropland; and 8 % from other land uses. Given the large agricultural land area in China, farming activities play an important role on the air-surface exchange over farmland. Particularly, rice field shift from a net sink (3.3 Mg uptake) during April-October (rice planting) to a net source when the farmland is not flooded (November-March). Summing up the emission from each land use, more than half of the total emission occurs in summer (51 %), followed by spring (28 %), autumn (13 %), and winter (8 %). Model verification is accomplished using observational data of air-soil/air-water fluxes and Hg deposition through litterfall for forest ecosystems in China and Monte Carlo simulations. In contrast to the earlier estimate by Shetty et al. (2008) that reported large emission from vegetative surfaces using an evapotranspiration approach, the estimate in

  18. The frictional response of patterned soft polymer surfaces

    NASA Astrophysics Data System (ADS)

    Rand, Charles J.

    2008-10-01

    Friction plays an intricate role in our everyday lives, it is therefore critical to understand the underlying features of friction to better help control and manipulate the response anywhere two surfaces in contact move past each other by a sliding motion. Here we present results targeting a thorough understanding of soft material friction and how it can be manipulated with patterns. We found that the naturally occurring length scale or periodicity (lambda) of frictionally induced patterns, Schallamach waves, could be described using two materials properties (critical energy release rate Gc and complex modulus (E*), i.e. lambdainfinity Gc /E*). Following this, we evaluated the effect of a single defect at a sliding interface. Sliding over a defect can be used to model the sliding from one feature to another in a patterned surface. Defects decreased the sliding frictional force by as much as 80% sliding and this decrease was attributed to changes in tangential stiffness of the sliding interface. The frictional response of surface wrinkles, where multiple edges or defects are acting in concert, was also evaluated. Wrinkles were shown to decrease friction (F) and changes in contact area (A) could not describe this decrease. A tangential stiffness correction factor (fx) and changes in the critical energy release rate were used to describe this deviation (F infinity Gc *A*fx/ℓ, where ℓ is a materials defined length scale of dissipation). This scaling can be used to describe the friction of any topographically patterned surface including the Gecko's foot, where the feature size is smaller than ℓ and thus replaces ℓ, increasing the friction compared to a flat surface. Also, mechanically-induced surface defects were used to align osmotically driven surface wrinkles by creating stress discontinuities that convert the global biaxial stress state to local uniaxial stresses. Defect spacing was used to control the alignment process at the surface of the wrinkled rigid

  19. An Extended Finite Element Method Formulation for Modeling the Response of Polycrystalline Materials to Dynamic Loading

    NASA Astrophysics Data System (ADS)

    Robbins, Joshua; Voth, Thomas E.

    2007-12-01

    The eXtended Finite Element Method (X-FEM) is a finite-element based discretization technique developed originally to model dynamic crack propagation [1]. Since that time the method has been used for modeling physics ranging from static meso-scale material failure to dendrite growth. Here we adapt the recent advances of Vitali and Benson [2] and Song et al. [3] to model dynamic loading of a polycrystalline material. We use demonstration problems to examine the method's efficacy for modeling the dynamic response of polycrystalline materials at the meso-scale. Specifically, we use the X-FEM to model grain boundaries. This approach allows us to i) eliminate ad-hoc mixture rules for multi-material elements and ii) avoid explicitly meshing grain boundaries.

  20. Amplification of Distant Estrogen Response Elements Deregulates Target Genes Associated with Tamoxifen Resistance in Breast Cancer

    PubMed Central

    Hsu, Pei-Yin; Hsu, Hang-Kai; Lan, Xun; Juan, Liran; Yan, Pearlly S.; Labanowska, Jadwiga; Heerema, Nyla; Hsiao, Tzu-Hung; Chiu, Yu-Chiao; Chen, Yidong; Liu, Yunlong; Li, Lang; Li, Rong; Thompson, Ian M.; Nephew, Kenneth P.; Sharp, Zelton D.; Kirma, Nameer B.; Jin, Victor X.; Huang, Tim H.-M.

    2013-01-01

    SUMMARY A causal role of gene amplification in tumorigenesis is well-known, while amplification of DNA regulatory elements as an oncogenic driver remains unclear. In this study, we integrated next-generation sequencing approaches to map distant estrogen response elements (DEREs) that remotely control transcription of target genes through chromatin proximity. Two densely mapped DERE regions located on chromosomes 17q23 and 20q13 were frequently amplified in ERα-positive luminal breast cancer. These aberrantly amplified DEREs deregulated target gene expression potentially linked to cancer development and tamoxifen resistance. Progressive accumulation of DERE copies was observed in normal breast progenitor cells chronically exposed to estrogenic chemicals. These findings may extend to other DNA regulatory elements, the amplification of which can profoundly alter target transcriptome during tumorigenesis. PMID:23948299

  1. EMG responses to maintain stance during multidirectional surface translations

    NASA Technical Reports Server (NTRS)

    Henry, S. M.; Fung, J.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

    1998-01-01

    To characterize muscle synergy organization underlying multidirectional control of stance posture, electromyographic activity was recorded from 11 lower limb and trunk muscles of 7 healthy subjects while they were subjected to horizontal surface translations in 12 different, randomly presented directions. The latency and amplitude of muscle responses were quantified for each perturbation direction. Tuning curves for each muscle were examined to relate the amplitude of the muscle response to the direction of surface translation. The latencies of responses for the shank and thigh muscles were constant, regardless of perturbation direction. In contrast, the latencies for another thigh [tensor fascia latae (TFL)] and two trunk muscles [rectus abdominis (RAB) and erector spinae (ESP)] were either early or late, depending on the perturbation direction. These three muscles with direction-specific latencies may play different roles in postural control as prime movers or as stabilizers for different translation directions, depending on the timing of recruitment. Most muscle tuning curves were within one quadrant, having one direction of maximal activity, generally in response to diagonal surface translations. Two trunk muscles (RAB and ESP) and two lower limb muscles (semimembranosus and peroneus longus) had bipolar tuning curves, with two different directions of maximal activity, suggesting that these muscle can play different roles as part of different synergies, depending on translation direction. Muscle tuning curves tended to group into one of three regions in response to 12 different directions of perturbations. Two muscles [rectus femoris (RFM) and TFL] were maximally active in response to lateral surface translations. The remaining muscles clustered into one of two diagonal regions. The diagonal regions corresponded to the two primary directions of active horizontal force vector responses. Two muscles (RFM and adductor longus) were maximally active orthogonal to

  2. Plant surface wax affects parasitoid's response to host footprints

    NASA Astrophysics Data System (ADS)

    Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

    2008-10-01

    The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

  3. Mercury (II) sensor based on monitoring dissociation rate of the trans-acting factor MerR from cis-element by surface plasmon resonance.

    PubMed

    Taniguchi, Masaki; Siddiki, Mohammad Shohel Rana; Ueda, Shunsaku; Maeda, Isamu

    2015-05-15

    Transcriptional switches regulate gene expression in response to environmental changes surrounding cell. Many studies have focused on two fundamentally different models of transcriptional control by bacterial metalloregulatory protein. Distortion of the DNA fragment including cis-element, to which the trans-acting factor MerR binds, is accepted as the mechanism of gene expression regulation by Hg (II) while, in cases of the other trans-acting factors ArsR and CadC, events of association to and dissociation from cis-element are known to control transcription in response to As (III) and Cd (II), respectively. In this study, interactions between green-fluorescent-protein-tagged trans-acting factor and immobilized cis-element were analyzed on solid surface. Fluorescent measurements and surface plasmon resonance (SPR) responses revealed that although the equilibrium dissociation constant (KD) was much lower in MerR than in ArsR and CadC, the dissociation rate of MerR from DNA increased in response to Hg (II) at concentrations of 5-10(4) µg l(-1). These results firstly demonstrate an increase of KD between MerR and its recognition site in DNA by Hg (II), and possibility of rapid Hg (II) quantification with the low detection limit (5 µg l(-1)) and the high dynamic range (10(1)-10(4) µg l(-1)).

  4. Growth Kinetics of Thiobacillus thiooxidans on the Surface of Elemental Sulfur.

    PubMed

    Konishi, Y; Asai, S; Yoshida, N

    1995-10-01

    The growth kinetics of Thiobacillus thiooxidans on elemental sulfur in batch cultures at 30(deg)C and pH 1.5 was studied by measuring the time courses of the concentration of adsorbed cells on sulfur, the concentration of free cells suspended in liquid medium, and the amount of sulfur oxidized. As the elemental sulfur was oxidized to sulfate ions, the surface concentration of adsorbed cells per unit mass of sulfur approached a maximum value (maximum adsorption capacity of sulfur particles) whereas the concentration of free cells continued to increase with time. There was a close relationship between the concentrations of free and adsorbed cells during the microbial sulfur oxidation, and the two cell concentrations were well correlated by the Langmuir isotherm with adsorption equilibrium constant K(infA) and maximum adsorption capacity X(infAm) of 2.10 x 10(sup-9) ml per cell and 4.57 x 10(sup10) cells per g, respectively. The total concentration of free and adsorbed cells increased in parallel with the amount of sulfate formed. The total growth on elemental sulfur gave a characteristic growth curve in which a linear-growth phase followed the period of an initial exponential phase. The batch rate data collected under a wide variety of inoculum levels (about 10(sup5) to 10(sup8) cells per ml) were consistent with a kinetic model assuming that the growth rate of adsorbed bacteria is proportional to the product of the concentration, X(infA), of adsorbed cells and the fraction, (theta)(infV), of adsorption sites unoccupied by cells. The kinetic and stoichiometric parameters appearing in the model were estimated from the experimental data, and the specific growth rate, (mu)(infA), and growth yield, Y(infA), were 2.58 day(sup-1) and 2.05 x 10(sup11) cells per g, respectively. The proposed model and the parameter values allowed us to predict quantitatively the surface attachment of T. thiooxidans cells on elemental sulfur and the bacterial growth in both initial

  5. CCQM Pilot Study CCQM-P140: Quantitative surface analysis of multi-element alloy films

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Joong; Jang, Jong Shik; Kim, An Soon; Suh, Jung Ki; Chung, Yong-Duck; Hodoroaba, Vasile-Dan; Wirth, Thomas; Unger, Wolfgang; Kang, Hee Jae; Popov, Oleg; Popov, Inna; Kuselman, Ilya; Lee, Yeon Hee; Sykes, David E.; Wang, Meiling; Wang, Hai; Ogiwara, Toshiya; Nishio, Mitsuaki; Tanuma, Shigeo; Simons, David; Szakal, Christopher; Osborn, William; Terauchi, Shinya; Ito, Mika; Kurokawa, Akira; Fujimoto, Toshiyuki; Jordaan, Werner; Jeong, Chil Seong; Havelund, Rasmus; Spencer, Steve; Shard, Alex; Streeck, Cornelia; Beckhoff, Burkhard; Eicke, Axel; Terborg, Ralf

    2015-01-01

    A pilot study for a quantitative surface analysis of multi-element alloy films has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study is to evaluate a protocol for a key comparison to demonstrate the equivalence of measures by National Metrology Institutes (NMIs) and Designated Institutes (DI) for the mole fractions of multi-element alloy films. A Cu(In,Ga)Se2 (CIGS) film with non-uniform depth distribution was chosen as a representative multi-element alloy film. The mole fractions of the reference and the test CIGS films were certified by isotope dilution—inductively coupled plasma/mass spectrometry. A total number counting (TNC) method was used as a method to determine the signal intensities of the constituent elements acquired in SIMS, XPS and AES depth profiling. TNC method is comparable with the certification process because the certified mole fractions are the average values of the films. The mole fractions of the CIGS films were measured by Secondary Ion Mass Spectrometry (SIMS), Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence (XRF) Analysis and Electron Probe Micro Analysis (EPMA) with Energy Dispersive X-ray Spectrometry (EDX). Fifteen laboratories from eight NMIs, one DI, and six non-NMIs participated in this pilot study. The average mole fractions of the reported data showed relative standard deviations from 5.5 % to 6.8 % and average relative expanded uncertainties in the range from 4.52 % to 4.86 % for the four test CIGS specimens. These values are smaller than those in the key comparison CCQM-K67 for the measurement of mole fractions of Fe-Ni alloy films. As one result it can be stated that SIMS, XPS and AES protocols relying on the quantification of CIGS films using the TNC method are mature to be used in a CCQM key comparison. Main text. To reach the main text of this paper, click on Final Report. The

  6. Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solution

    SciTech Connect

    DePaolo, D.

    2010-10-15

    A surface reaction kinetic model is developed for predicting Ca isotope fractionation and metal/Ca ratios of calcite as a function of rate of precipitation from aqueous solution. The model is based on the requirements for dynamic equilibrium; i.e. proximity to equilibrium conditions is determined by the ratio of the net precipitation rate (R{sub p}) to the gross forward precipitation rate (R{sub f}), for conditions where ionic transport to the growing crystal surface is not rate-limiting. The value of R{sub p} has been experimentally measured under varying conditions, but the magnitude of R{sub f} is not generally known, and may depend on several factors. It is posited that, for systems with no trace constituents that alter the surface chemistry, R{sub f} can be estimated from the bulk far-from-equilibrium dissolution rate of calcite (R{sub b} or k{sub b}), since at equilibrium R{sub f} = R{sub b}, and R{sub p} = 0. Hence it can be inferred that R{sub f} {approx} R{sub p} + R{sub b}. The dissolution rate of pure calcite is measureable and is known to be a function of temperature and pH. At given temperature and pH, equilibrium precipitation is approached when R{sub p} (= R{sub f} - R{sub b}) << R{sub b}. For precipitation rates high enough that R{sub p} >> R{sub b}, both isotopic and trace element partitioning are controlled by the kinetics of ion attachment to the mineral surface, which tend to favor more rapid incorporation of the light isotopes of Ca and discriminate weakly between trace metals and Ca. With varying precipitation rate, a transition region between equilibrium and kinetic control occurs near R{sub p} {approx} R{sub b} for Ca isotopic fractionation. According to this model, Ca isotopic data can be used to estimate R{sub f} for calcite precipitation. Mechanistic models for calcite precipitation indicate that the molecular exchange rate is not constant at constant T and pH, but rather is dependent also on solution saturation state and hence R{sub p

  7. Structure response and damage produced by airblast from surface mining

    SciTech Connect

    Siskind, D.E.; Stachura, V.J.; Stagg, M.S.; Kopp, J.W.

    1980-01-01

    The Bureau of Mines studied airblast from surface mining to assess its damage and annoyance potential, and to determine safe levels and appropriate measurement techniques. Research results obtained from direct measurements of airblast-produced structure responses, damage, and analysis of instrument characteristics were combined with studies of sonic booms and human response to transient overpressures. Safe levels of airblast were found to be 134 db (0.1 Hz), 133 db (2 Hz), 129 db (6 Hz), and 105 db C-slow. These four airblast levels and measurement methods are equivalent in terms of structure response, and any one could be used as a safe-level criterion. Of the four methods, only the 0.1-Hz high-pass linear method accurately measures the total airblast energy present; however, the other three were found to adequately quantify the structure response and also represent techniques that are readily available to industry. Where a single airblast measuring system must be used, the 2-Hz linear peak response is the best overall compromise. The human response and annoyance problem from airblast is probably caused primarily by wall rattling and the resulting secondary noises. Although these will not entirely be precluded by the recommended levels, they are low enough to preclude damage to residential structures and any possible human injury over the long term.

  8. [Responses of Pinus koraiensis tree ring cell scale parameters to climate elements in Changbai Mountains].

    PubMed

    Wang, Hui; Shao, Xue-mei; Fang, Xiu-qi; Yin, Zhi-yong; Chen, Li; Zhao, Dong-sheng; Wu, Shao-hong

    2011-10-01

    Based on the tree ring samples of Pinus koraiensis collected from the low altitude areas of Changbai Mountains, seven standard chronologies for tree ring width and cell scale parameters were constructed. Parts of the chronologies were chosen for the correlation analysis with the climate elements in 1959-2007 at Donggang meteorological station, and the changes of the correlations between tree ring indices and climate elements before and after 1988 in which the climate changed abruptly were discussed. In the seven standard chronologies constructed, cell number had the best correlation with tree ring width. Both precipitation and air temperature were the limiting factors for the growth of P. koraiensis, but the chronologies had better correlation with precipitation than with air temperature, mainly manifested in the significant correlation between the chronologies and the precipitation in previous September and current May and June. Comparing with tree ring width, cell size could reveal more climatic information, mainly manifested in the positive correlation between the chronologies and the air temperature in March and the precipitation in May, and the negative correlation between the chronologies and the air temperature in May. After the abrupt change of air temperature in 1988, the responses of cell size to climate elements had some changes, mainly manifested in the decreasing sensitivity to monthly climate elements and the earlier response time.

  9. Mineral elements of subtropical tree seedlings in response to elevated carbon dioxide and nitrogen addition.

    PubMed

    Huang, Wenjuan; Zhou, Guoyi; Liu, Juxiu; Zhang, Deqiang; Liu, Shizhong; Chu, Guowei; Fang, Xiong

    2015-01-01

    Mineral elements in plants have been strongly affected by increased atmospheric carbon dioxide (CO2) concentrations and nitrogen (N) deposition due to human activities. However, such understanding is largely limited to N and phosphorus in grassland. Using open-top chambers, we examined the concentrations of potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), copper (Cu) and manganese (Mn) in the leaves and roots of the seedlings of five subtropical tree species in response to elevated CO2 (ca. 700 μmol CO2 mol(-1)) and N addition (100 kg N ha(-1) yr(-1)) from 2005 to 2009. These mineral elements in the roots responded more strongly to elevated CO2 and N addition than those in the leaves. Elevated CO2 did not consistently decrease the concentrations of plant mineral elements, with increases in K, Al, Cu and Mn in some tree species. N addition decreased K and had no influence on Cu in the five tree species. Given the shifts in plant mineral elements, Schima superba and Castanopsis hystrix were less responsive to elevated CO2 and N addition alone, respectively. Our results indicate that plant stoichiometry would be altered by increasing CO2 and N deposition, and K would likely become a limiting nutrient under increasing N deposition in subtropics. PMID:25794046

  10. Finite element method analysis of surface acoustic wave devices with microcavities for detection of liquids

    NASA Astrophysics Data System (ADS)

    Senveli, Sukru U.; Tigli, Onur

    2013-12-01

    This paper introduces the use of finite element method analysis tools to investigate the use of a Rayleigh type surface acoustic wave (SAW) sensor to interrogate minute amounts of liquids trapped in microcavities placed on the delay line. Launched surface waves in the ST-X quartz substrate couple to the liquid and emit compressional waves. These waves form a resonant cavity condition and interfere with the surface waves in the substrate. Simulations show that the platform operates in a different mechanism than the conventional mass loading of SAW devices. Based on the proposed detection mechanism, it is able to distinguish between variations of 40% and 90% glycerin based on phase relations while using liquid volumes smaller than 10 pl. Results from shallow microcavities show high correlation with sound velocity parameter of the liquid whereas deeper microcavities display high sensitivities with respect to glycerin concentration. Simulated devices yield a maximum sensitivity of -0.77°/(% glycerin) for 16 μm wavelength operation with 8 μm deep, 24 μm wide, and 24 μm long microcavities.

  11. Finite element analysis on influence of implant surface treatments, connection and bone types.

    PubMed

    Santiago Junior, Joel Ferreira; Verri, Fellippo Ramos; Almeida, Daniel Augusto de Faria; de Souza Batista, Victor Eduardo; Lemos, Cleidiel Aparecido Araujo; Pellizzer, Eduardo Piza

    2016-06-01

    The aim of this study is to assess the effect of different dental implant designs, bone type, loading, and surface treatment on the stress distribution around the implant by using the 3D finite-element method. Twelve 3D models were developed with Invesalius 3.0, Rhinoceros 4.0, and Solidworks 2010 software. The analysis was processed using the FEMAP 10.2 and NeiNastran 10.0 software. The applied oblique forces were 200 N and 100 N. The results were analyzed using maps of maximum principal stress and bone microstrain. Statistical analysis was performed using ANOVA and Tukey's test. The results showed that the Morse taper design was most efficient in terms of its distribution of stresses (p<0.05); the external hexagon with platform switching did not show a significant difference from an external hexagon with a standard platform (p>0.05). The different bone types did not show a significant difference in the stress/strain distribution (p>0.05). The surface treatment increased areas of stress concentration under axial loading (p<0.05) and increased areas of microstrain under axial and oblique loading (p<0.05) on the cortical bone. The Morse taper design behaved better biomechanically in relation to the bone tissue. The treated surface increased areas of stress and strain on the cortical bone tissue.

  12. Finite Element Surface Registration Incorporating Curvature, Volume Preservation, and Statistical Model Information

    PubMed Central

    Lüthi, Marcel; Vetter, Thomas

    2013-01-01

    We present a novel method for nonrigid registration of 3D surfaces and images. The method can be used to register surfaces by means of their distance images, or to register medical images directly. It is formulated as a minimization problem of a sum of several terms representing the desired properties of a registration result: smoothness, volume preservation, matching of the surface, its curvature, and possible other feature images, as well as consistency with previous registration results of similar objects, represented by a statistical deformation model. While most of these concepts are already known, we present a coherent continuous formulation of these constraints, including the statistical deformation model. This continuous formulation renders the registration method independent of its discretization. The finite element discretization we present is, while independent of the registration functional, the second main contribution of this paper. The local discontinuous Galerkin method has not previously been used in image registration, and it provides an efficient and general framework to discretize each of the terms of our functional. Computational efficiency and modest memory consumption are achieved thanks to parallelization and locally adaptive mesh refinement. This allows for the first time the use of otherwise prohibitively large 3D statistical deformation models. PMID:24187581

  13. Finite element surface registration incorporating curvature, volume preservation, and statistical model information.

    PubMed

    Albrecht, Thomas; Dedner, Andreas; Lüthi, Marcel; Vetter, Thomas

    2013-01-01

    We present a novel method for nonrigid registration of 3D surfaces and images. The method can be used to register surfaces by means of their distance images, or to register medical images directly. It is formulated as a minimization problem of a sum of several terms representing the desired properties of a registration result: smoothness, volume preservation, matching of the surface, its curvature, and possible other feature images, as well as consistency with previous registration results of similar objects, represented by a statistical deformation model. While most of these concepts are already known, we present a coherent continuous formulation of these constraints, including the statistical deformation model. This continuous formulation renders the registration method independent of its discretization. The finite element discretization we present is, while independent of the registration functional, the second main contribution of this paper. The local discontinuous Galerkin method has not previously been used in image registration, and it provides an efficient and general framework to discretize each of the terms of our functional. Computational efficiency and modest memory consumption are achieved thanks to parallelization and locally adaptive mesh refinement. This allows for the first time the use of otherwise prohibitively large 3D statistical deformation models.

  14. Extended volume and surface scatterometer for optical characterization of 3D-printed elements

    NASA Astrophysics Data System (ADS)

    Dannenberg, Florian; Uebeler, Denise; Weiß, Jürgen; Pescoller, Lukas; Weyer, Cornelia; Hahlweg, Cornelius

    2015-09-01

    The use of 3d printing technology seems to be a promising way for low cost prototyping, not only of mechanical, but also of optical components or systems. It is especially useful in applications where customized equipment repeatedly is subject to immediate destruction, as in experimental detonics and the like. Due to the nature of the 3D-printing process, there is a certain inner texture and therefore inhomogeneous optical behaviour to be taken into account, which also indicates mechanical anisotropy. Recent investigations are dedicated to quantification of optical properties of such printed bodies and derivation of corresponding optimization strategies for the printing process. Beside mounting, alignment and illumination means, also refractive and reflective elements are subject to investigation. The proposed measurement methods are based on an imaging nearfield scatterometer for combined volume and surface scatter measurements as proposed in previous papers. In continuation of last year's paper on the use of near field imaging, which basically is a reflective shadowgraph method, for characterization of glossy surfaces like printed matter or laminated material, further developments are discussed. The device has been extended for observation of photoelasticity effects and therefore homogeneity of polarization behaviour. A refined experimental set-up is introduced. Variation of plane of focus and incident angle are used for separation of various the images of the layers of the surface under test, cross and parallel polarization techniques are applied. Practical examples from current research studies are included.

  15. Gaseous Elemental Mercury (GEM) Emissions from Snow Surfaces in Northern New York

    PubMed Central

    Maxwell, J. Alexander; Holsen, Thomas M.; Mondal, Sumona

    2013-01-01

    Snow surface-to-air exchange of gaseous elemental mercury (GEM) was measured using a modified Teflon fluorinated ethylene propylene (FEP) dynamic flux chamber (DFC) in a remote, open site in Potsdam, New York. Sampling was conducted during the winter months of 2011. The inlet and outlet of the DFC were coupled with a Tekran Model 2537A mercury (Hg) vapor analyzer using a Tekran Model 1110 two port synchronized sampler. The surface GEM flux ranged from −4.47 ng m−2 hr−1 to 9.89 ng m−2 hr−1. For most sample periods, daytime GEM flux was strongly correlated with solar radiation. The average nighttime GEM flux was slightly negative and was not well correlated with any of the measured meteorological variables. Preliminary, empirical models were developed to estimate GEM emissions from snow surfaces in northern New York. These models suggest that most, if not all, of the Hg deposited with and to snow is reemitted to the atmosphere. PMID:23874951

  16. Mechanical Stress Induces Biotic and Abiotic Stress Responses via a Novel cis-Element

    PubMed Central

    Walley, Justin W; Coughlan, Sean; Hudson, Matthew E; Covington, Michael F; Kaspi, Roy; Banu, Gopalan; Harmer, Stacey L; Dehesh, Katayoon

    2007-01-01

    Plants are continuously exposed to a myriad of abiotic and biotic stresses. However, the molecular mechanisms by which these stress signals are perceived and transduced are poorly understood. To begin to identify primary stress signal transduction components, we have focused on genes that respond rapidly (within 5 min) to stress signals. Because it has been hypothesized that detection of physical stress is a mechanism common to mounting a response against a broad range of environmental stresses, we have utilized mechanical wounding as the stress stimulus and performed whole genome microarray analysis of Arabidopsis thaliana leaf tissue. This led to the identification of a number of rapid wound responsive (RWR) genes. Comparison of RWR genes with published abiotic and biotic stress microarray datasets demonstrates a large overlap across a wide range of environmental stresses. Interestingly, RWR genes also exhibit a striking level and pattern of circadian regulation, with induced and repressed genes displaying antiphasic rhythms. Using bioinformatic analysis, we identified a novel motif overrepresented in the promoters of RWR genes, herein designated as the Rapid Stress Response Element (RSRE). We demonstrate in transgenic plants that multimerized RSREs are sufficient to confer a rapid response to both biotic and abiotic stresses in vivo, thereby establishing the functional involvement of this motif in primary transcriptional stress responses. Collectively, our data provide evidence for a novel cis-element that is distributed across the promoters of an array of diverse stress-responsive genes, poised to respond immediately and coordinately to stress signals. This structure suggests that plants may have a transcriptional network resembling the general stress signaling pathway in yeast and that the RSRE element may provide the key to this coordinate regulation. PMID:17953483

  17. Elemental characteristics of surface suspended particulates off the Changjiang estuary during the 1998 flood

    NASA Astrophysics Data System (ADS)

    Hsu, Shih-Chieh; Lin, Fei-Jan

    2010-06-01

    Surface suspended particulate matter (SPM) samples were collected on two latitudinal transects over the Changjiang estuary, covering a wide salinity regime from 8 to 30‰, instantaneously after the largest Changjiang flood peak in August 1998 that caused severe disaster in China. They have been analyzed for 20 major and trace elements and 7 rare earth elements (REEs) using ICP-MS. The SPM concentrations varied a very wide range of up to two orders of magnitude, sharply decreasing southward from 18 mg/l in the Changjiang river mouth to less than 1 mg/l at around 28°N, which may be representative of a background in the East China Sea (ECS) shelf. All selected particulate elements exhibit large variability in space. SPM collected around the Changjiang river mouth was dominated by the lithogenic components approximately accounting for 80% or more of the bulk, and when going south the proportions decreased to less than half of the total. Based on the results of enrichment factor (EF) calculation, elements Fe, Ti, Mn, Ba, Sr, Co, Be, Tl, Nb, V, Ni, and Mo with mean EF values of less than 3 were categorized into the unpolluted group, and elements Zn, Cu, Pb, As, Ag, and Sb with EF values of higher than 5 into the polluted group. This investigation demonstrated that anthropogenic metals could be dispersed over a large extent along the Chinese coast and on the ECS shelf although a majority of terrigenous sediments would be deposited within the Changjiang estuary. Additionally, our study reveals that the Qiantangjiang might contribute non-negligible pollutants to Hangzhou Bay. We therefore argue that the study area has been in moderate pollution, different from most of previous suggestions. Overall, most samples have similar chondrite- and especially UCC-normalized distribution patterns (UCC: upper continental crust); the sample/UCC ratios of REEs generally vary within a factor of 3 and display a flat (or slightly convex) pattern, essentially revealing little fractionation

  18. An extended finite element formulation for modeling the response of polycrystalline materials to shock loading

    NASA Astrophysics Data System (ADS)

    Robbins, Joshua; Voth, Thomas

    2007-06-01

    The eXtended Finite Element Method (X-FEM) is a finite element based discretization technique developed originally to model dynamic crack propagation [1]. Since that time the method has been used for modeling physics ranging from static mesoscale material failure to dendrite growth. Here we adapt the recent advances of Benson et al. [2] and Belytchko et al. [3] to model shock loading of polycrystalline material. Through several demonstration problems we evaluate the method for modeling the shock response of polycrystalline materials at the mesoscale. Specifically, we use the X-FEM to model grain boundaries. This approach allows us to i) eliminate ad-hoc mixture rules for multi-material elements and ii) avoid explicitly meshing grain boundaries. ([1] N. Moes, J. Dolbow, J and T. Belytschko, 1999,``A finite element method for crack growth without remeshing,'' International Journal for Numerical Methods in Engineering, 46, 131-150. [2] E. Vitali, and D. J. Benson, 2006, ``An extended finite element formulation for contact in multi-material arbitrary Lagrangian-Eulerian calculations,'' International Journal for Numerical Methods in Engineering, 67, 1420-1444. [3] J-H Song, P. M. A. Areias and T. Belytschko, 2006, ``A method for dynamic crack and shear band propagation with phantom nodes,'' International Journal for Numerical Methods in Engineering, 67, 868-893.)

  19. Simulation of the ultrasonic array response from real branched cracks using an efficient finite element method

    SciTech Connect

    Felice, Maria V.; Velichko, Alexander; Wilcox, Paul D.; Barden, Tim J.; Dunhill, Tony K.

    2014-02-18

    A hybrid model to simulate the ultrasonic array response from stress corrosion cracks is presented. These cracks are branched and difficult to detect so the model is required to enable optimization of an array design. An efficient frequency-domain finite element method is described and selected to simulate the ultrasonic scattering. Experimental validation results are presented, followed by an example of the simulated ultrasonic array response from a real stress corrosion crack whose geometry is obtained from an X-ray Computed Tomography image. A simulation-assisted array design methodology, which includes the model and use of real crack geometries, is proposed.

  20. Isolation of transcription factors binding auxin response elements using a yeast one-hybrid system.

    PubMed

    Qi, Mei; Huang, Meijuan; Chen, Fan

    2002-04-01

    Plant hormones play an important role during higher plant embryogenesis. Auxin is central to the development of vascular tissues, formation of lateral and adventitious roots, control of apical dominance, and tropic responses. Auxin response element (AuxRE), present in the promoters of many auxin-induced genes, can confer auxin responsiveness. Using carrot somatic embryo under specific developmental phase, a cDNA expression library was constructed. Several plasmids were recombined containing the tetramer of AuxRE as a bait. After screening by a yeast one-hy-brid system, one positive clone was confirmed and characterized. Electrophoretic mobility shift assay showed that AxRF1 protein expressed in yeast cell could bind AuxRE in vitro. It suggests that AxRF1 participates in regulation of the expression of auxin responsive gene during carrot somatic embryogenesis. PMID:18763077

  1. Nuclear receptor coactivators facilitate vitamin D receptor homodimer action on direct repeat hormone response elements.

    PubMed

    Takeshita, A; Ozawa, Y; Chin, W W

    2000-03-01

    Vitamin D receptor (VDR) is a ligand-dependent transcription factor that regulates target gene expression. Although VDR forms stable heterodimer complex with retinoid X receptors (RXRs) on vitamin D-response elements (VDREs), it is still not clear whether VDR/RXR heterodimers are the only VDR complexes responsible for vitamin D-mediated gene transcription. In this report, we analyzed the effect of nuclear receptor coactivators (SRC-1 and TRAM-1) on VDR homodimer and VDR/RXR heterodimer formation by electrophoretic mobility shift assay. We found that VDR forms stable homodimers after interaction with the coactivators on a VDRE (DR+3). Of particular note, DR+4 and DR+5 hormone-response elements (HREs) may also support such interactions. Cotransfection experiments revealed further that the coactivators enhance ligand-induced VDR transcription on these elements. Our studies suggest the important role of VDR homodimers, in addition to VDR/RXR heterodimers, in vitamin D-induced transactivation. Thus, specific coactivator-VDR interactions on HREs may determine target gene transactivation.

  2. Global observations and modeling of atmosphere-surface exchange of elemental mercury: a critical review

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Lin, Che-Jen; Wang, Xun; Sommar, Jonas; Fu, Xuewu; Feng, Xinbin

    2016-04-01

    Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg0) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg0. Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O3, radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling. We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg0 flux observations in East

  3. A finite-element visualization of quantum reactive scattering. II. Nonadiabaticity on coupled potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Warehime, Mick; Kłos, Jacek; Alexander, Millard H.

    2015-01-01

    This is the second in a series of papers detailing a MATLAB based implementation of the finite element method applied to collinear triatomic reactions. Here, we extend our previous work to reactions on coupled potential energy surfaces. The divergence of the probability current density field associated with the two electronically adiabatic states allows us to visualize in a novel way where and how nonadiabaticity occurs. A two-dimensional investigation gives additional insight into nonadiabaticity beyond standard one-dimensional models. We study the F(2P) + HCl and F(2P) + H2 reactions as model applications. Our publicly available code (http://www2.chem.umd.edu/groups/alexander/FEM) is general and easy to use.

  4. Element concentrations in surface soils of the Coconino Plateau, Grand Canyon region, Coconino County, Arizona

    USGS Publications Warehouse

    Van Gosen, Bradley S.

    2016-09-15

    This report provides the geochemical analyses of a large set of background soils collected from the surface of the Coconino Plateau in northern Arizona. More than 700 soil samples were collected at 46 widespread areas, sampled from sites that appear unaffected by mineralization and (or) anthropogenic contamination. The soils were analyzed for 47 elements, thereby providing data on metal concentrations in soils representative of the plateau. These background concentrations can be used, for instance, for comparison to metal concentrations found in soils potentially affected by natural and anthropogenic influences on the Coconino Plateau in the Grand Canyon region of Arizona.The soil sampling survey revealed low concentrations for the metals most commonly of environmental concern, such as arsenic, cobalt, chromium, copper, mercury, manganese, molybdenum, lead, uranium, vanadium, and zinc. For example, the median concentrations of the metals in soils of the Coconino Plateau were found to be comparable to the mean values previously reported for soils of the western United States.

  5. A finite-element visualization of quantum reactive scattering. II. Nonadiabaticity on coupled potential energy surfaces

    SciTech Connect

    Warehime, Mick; Kłos, Jacek; Alexander, Millard H.

    2015-01-21

    This is the second in a series of papers detailing a MATLAB based implementation of the finite element method applied to collinear triatomic reactions. Here, we extend our previous work to reactions on coupled potential energy surfaces. The divergence of the probability current density field associated with the two electronically adiabatic states allows us to visualize in a novel way where and how nonadiabaticity occurs. A two-dimensional investigation gives additional insight into nonadiabaticity beyond standard one-dimensional models. We study the F({sup 2}P) + HCl and F({sup 2}P) + H{sub 2} reactions as model applications. Our publicly available code (http://www2.chem.umd.edu/groups/alexander/FEM) is general and easy to use.

  6. A Novel Peroxisome Proliferator Response Element Modulates Hepatic Low Density Lipoprotein Receptor Gene Transcription in Response to PPARδ Activation

    PubMed Central

    Shende, Vikram R.; Singh, Amar Bahadur; Liu, Jingwen

    2016-01-01

    The hepatic expression of LDLR gene is regulated primarily at the transcriptional level by a sterol-regulatory element (SRE) in its proximal promoter region which is the site of action of SRE-binding protein 2 (SREBP2). However whether additional cis-regulatory elements contribute to LDLR transcription has not been fully explored. We investigated the function of a putative PPAR-response element (PPRE) sequence motif located at −768 to −752 bases upstream of the transcription start site of human LDLR gene in response to PPARδ activation. Promoter luciferase reporter analyses showed that treating HepG2 cells with PPARδ agonist L165041 markedly increased the activity of a full-length LDLR promoter construct (pLDLR-1192) without any effects on the shorter promoter reporter pLDLR-234 that contains only the core regulatory elements SRE-1 and SP1 sites. Importantly, mutation of the PPRE sequence greatly attenuated the induction of the full-length LDLR promoter activity by L165041 without affecting rosuvastatin mediated transactivation. Electrophoretic mobility shift and chromatin immunoprecipitation assays further confirmed the binding of PPARδ to the LDLR-PPRE site. Treating HepG2 cells with L165041 elevated the mRNA and protein expressions of LDLR without affecting the LDLR mRNA decay rate. The induction of LDLR expression by PPARδ agonist was further observed in liver tissue of mice and hamsters treated with L165041. Altogether, our studies identify a novel PPRE-mediated regulatory mechanism for LDLR transcription and suggest that combined treatment of statin with PPARδ agonists may have advantageous effects on LDLR expression. PMID:26443862

  7. Investigation of turbulent wedges generated by different single surface roughness elements

    NASA Astrophysics Data System (ADS)

    Traphan, Dominik; Meinlschmidt, Peter; Lutz, Otto; Peinke, Joachim; Gülker, Gerd

    2013-11-01

    It is known that small faults on rotor blades of wind turbines can cause significant power loss. In order to better understand the governing physical effects, in this experimental study, the formation of a turbulent wedge over a flat plate induced by single surface roughness elements is under investigation. The experiments are performed at different ambient pressure gradients, thus allowing conclusions about the formation of a turbulent wedge over an airfoil. With respect to typical initial faults on operating airfoils, the roughness elements are modified in both size and shape (raised or recessed). None intrusive experimental methods, such as stereoscopic PIV and LDA, enable investigations based on temporally and spatially highly resolved velocity measurements. In this way, a spectral analysis of the turbulent boundary layer is performed and differences in coherent structures within the wedge are identified. These findings are correlated with global measurements of the wedge carried out by infrared thermography. This correlation aims to enable distinguishing the cause and main properties of a turbulent wedge by the easy applicable method of infrared thermography, which is of practical relevance in the field of condition monitoring of wind turbines.

  8. Elemental Analyses of Hypervelocity Microparticle Impact Sites on Interplanetary Dust Experiment Sensor Surfaces

    NASA Technical Reports Server (NTRS)

    Simon, C. G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. A.; Wortman, J. J.; Brownlee, D. E.

    1992-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity microparticles (approximately 0.2 to approximately 100 micron diameter) that struck the active sensors with enough energy to breakdown the 0.4 or 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. The high purity Al-SiO2-Si substrates allowed detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) was used to create two-dimensional elemental ion intensity maps of microparticle sites on the IDE sensors. The element intensities in the central craters of the impacts were corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results classification resulted from the particles' origins as 'manmade', 'natural', or 'indeterminate'. The last classification resulted from the presence of too little impactor residue, analytical interference from high background contamination, the lack of information on silicon and aluminum residues, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. Thus far, a total of 79 randomly selected microparticle impact sites from the six primary sides of the LDEF were analyzed: 36 from tray C-9 (Leading (ram), or east, side), 18 from tray C-3 (Trailing

  9. X-Ray Dichroism in Photoelectron Spectroscopy for Direct Element Specific Surface Magnetometry of Nanomagnetic Structures

    NASA Astrophysics Data System (ADS)

    Tobin, James G.

    1997-03-01

    Element specific surface magnetometry remains a central goal of synchrotron radiation based studies of nanomagnetic structures. One appealing possibility is the combination of xray absorption dichroism measurements and the theoretical framework provided by the "sum rules."[1] Unfortunately, sum rule analyses are hampered by several limitations [2], including delocalization of the final state, multi-electronic phenomena and the presence of surface dipoles. An alternative experiment, Magnetic Xray Dichroism in Photoelectron Spectroscopy, holds out promise based upon its elemental specificity, surface sensitivity and high resolution. Computational simulations by Tamura et al [3] demonstrated the relationship between exchange and spin orbit splittings and experimental data of linear and circular dichroisms. Now we [4] have developed an analytical framework which allows for the direct extraction of core level exchange splittings from circular and linear dichroic photoemission data. By extending a model initially proposed by Venus [5], it is possible to show a linear relation between normalized dichroism peaks in the experimental data and the underlying exchange splitting. Since it is reasonable to expect that exchange splittings and magnetic moments track together [6], this measurement thus becomes a powerful new tool for direct surface magnetometry, without recourse to time consuming and difficult spectral simulations. The theoretical derivation will be supported by high resolution linear and circular dichroism data collected at the Spectromicroscopy Facility of the Advanced Light Source. [7,8] This work was performed under the auspices of the U.S. Department of Energy by LLNL under contract No. W-7405-ENG-48. 1. B.T. Thole et al, Phys. Rev. Lett. 68,1943 (1992); P. Carra et al. Phys. Rev. Lett. 70, 694 (1993). 2. J.G. Tobin et al Phys. Rev. B 52, 6530 (1995). 3. E. Tamura et al, Phys. Rev. Lett 73, 1533 (1994) 4. J.G. Tobin, K.W. Goodman, F.O. Schumann, R.F. Willis, J

  10. Elemental analyses of hypervelocity microparticle impact sites on Interplanetary Dust Experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. A.; Wortman, Jim J.; Brownlee, D. E.

    1993-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity microparticles (approximately 0.2 to approximately 100 micron diameter) that struck the active sensors with enough energy to break down the 0.4 or 1.0 micron thick SIO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. The high purity Al-SiO2-Si substrates allowed detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) was used to create two-dimensional elemental ion intensity maps of microparticle impact sites on the IDE sensors. The element intensities in the central craters of the impacts were corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results were used to classify the particles' origins as 'manmade,' 'natural,' or 'indeterminate.' The last classification resulted from the presence of too little impactor residue, analytical interference from high background contamination, the lack of information on silicon and aluminum residues, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters of these features. Thus far a total of 79 randomly selected microparticle impact sites from the six primary sides of the LDEF have been analyzed: 36 from tray C-9 (Leading (ram), or East, side), 18 from tray C-3

  11. Characterization of the antioxidant responsive element (ARE): A xenobiotic responsive element controlling expression of the rat glutathione S-transferase Ya subunit gene by phenolic antioxidants

    SciTech Connect

    Rushmore, T.H.; Pickett, C.B. )

    1991-03-11

    The antioxidant responsive element (ARE) is responsible for part of the basal level expression of the Ya subunit gene and for the induction by phenolic antioxidants and metabolites of planar aromatic hydrocarbons (PAH), such as {beta}-naphthoflavone ({beta}-NF). As an initial step in the characterization of the mechanism(s) by which phenolic antioxidants and metabolites of PAH activate transcription via the ARE, the authors prepared 5{prime} and 3{prime}-deletions and point mutants of the 41 bp ARE, transfected them into HepG2 cells and monitored the basal and {beta}-NF inducible activities. Deletion analysis permitted separation of the basal and {beta}-NF inducible components of the ARE. The minimum sequence required for {beta}-NF inducible expression was PuGTGACAAAGCAPu, nucleotides {minus}697 to {minus}687. Point mutations at nucleotides {minus}696, {minus}695, {minus}694, {minus}693, {minus}689 or {minus}688 abolished the {beta}-NF inducible expression. Mutations at the other positions had little or no effect on {beta}-NF inducible expression. Gel shift assays suggest that at least 2 proteins bind to regions within the ARE shown to be important for basal and {beta}-NF inducible expression.

  12. Surface Markers for the Murine Oval Cell Response

    PubMed Central

    Dorrell, Craig; Erker, Laura; Lanxon-Cookson, Kelsea M.; Abraham, Stephanie L.; Victoroff, Tristan; Ro, Simon; Canaday, Pamela S.; Streeter, Philip R.; Grompe, Markus

    2011-01-01

    The biology of progenitor activation in the liver is of considerable medical and scientific interest. The powerful genetic tools available for the mouse make it an ideal model system to study this complex process involving many different cell types. However, reagents for the isolation and study of distinct hepatic subpopulations have been quite limited compared to those available for hematopoietic cells. To produce cell surface reactive reagents more specific for the oval cell response, we generated a new collection of monoclonal antibodies by immunization of Fischer rats with enzymatically dispersed nonparenchymal cells from the livers of adult mice treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Each of the resulting antibodies recognized a surface antigen present on a liver cell subset and permitted the viable isolation of the associated subpopulation by fluorescence-activated cell sorting. Differential activity was observed on normal liver cells and at different stages of oval cell activation, indicating potential utility for progenitor cell identification. The subdivision of liver cells using these tools should facilitate the study of the biology of ductal and periductal hepatic cell types, including progenitors. Conclusion A new panel of surface reactive monoclonal antibodies to support investigation of the murine oval cell response has been developed. PMID:18726953

  13. Surface Chemistry of Nanocellulose Fibers Directs Monocyte/Macrophage Response.

    PubMed

    Hua, Kai; Ålander, Eva; Lindström, Tom; Mihranyan, Albert; Strømme, Maria; Ferraz, Natalia

    2015-09-14

    The effect of surface functionalization of nanofibrillated cellulose (NFC) on monocyte/macrophage (MM) behavior is investigated to understand how the physicochemical properties of nanocelluloses influence the interactions of such materials with biological systems. Films of anionic (a-), cationic (c-), and unmodified (u-) NFC were synthesized and characterized in terms of surface charge. THP-1 monocytes were cultured on the surface of the films for 24 h in the presence and absence of lipopolysaccharide, and the cell response was evaluated in terms of cell adhesion, morphology, and secretion of TNF-α, IL-10, and IL-1ra. The results show that MMs cultured on carboxymethylated-NFC films (a-NFC) are activated toward a proinflammatory phenotype, whereas u-NFC promotes a mild activation of the studied cells. The presence of hydroxypropyltrimethylammonium groups on c-NFC, however, does not promote the activation of MMs, indicating that c-NFC closely behaves as an inert material in terms of MM activation. None of the materials is able to directly activate the MMs toward an anti-inflammatory response. These results may provide a foundation for the design of future NFC-based materials with the ability to control MM activation and may expand the use of NFC in biomedical applications.

  14. Trace element concentrations and bioindicator responses in tree swallows from northwestern Minnesota

    USGS Publications Warehouse

    Custer, Christine M.; Custer, T.W.; Warburton, D.; Hoffman, D.J.; Bickham, J.W.; Matson, C.W.

    2006-01-01

    Abstract Extremely high concentrations of cadmium (3.5 ug/g dry wgt.) and elevated concentrations of chromium (>10 ug/g dry wgt.) and mercury (1.6 ug/g dry wgt.) were reported in waterbird tissues at Agassiz National Wildlife Refuge in northwestern Minnesota in 1994. Tree swallows (Tachycineta bicolor) were studied during 1998-2001 at three drainages into the Refuge, two pools on the Refuge, and at a nearby reference location to document whether high levels of contaminants were still present, and if so to quantify the source and severity of the contamination. Trace elements were measured in tree swallow eggs, livers, and diet. Reproductive success and bioindicator responses were monitored. In 2000, water was drawn down on Agassiz Pool, one of the main pools on the Refuge. This presented an opportunity to evaluate the response of trace element concentrations in the diet and tissues of tree swallows after reflooding. High concentrations of trace elements were not detected in swallow tissues, nor were there differences among locations. Less than 20% of swallow samples had detectable concentrations of cadmium or chromium. Mercury concentrations were low and averaged <0.25 ug/g dry wgt. in swallow tissues. Trace elements, including mercury, did not increase in tree swallows following the 2000 drawdown at Agassiz Pool. Hatching success and survival of nestlings to 12 days-of-age for tree swallows on the Refuge were similar to the national average and consistent with background trace element concentrations. Bioindicator measurements were within the normal ranges as well.

  15. Surface properties and early murine pre-osteoblastic cell responses of phosphoric acid modified titanium surface

    PubMed Central

    Osathanon, Thanaphum; Sawangmake, Chenphop; Ruangchainicom, Nanticha; Wutikornwipak, Pavitra; Kantukiti, Panisa; Nowwarote, Nunthawan; Pavasant, Prasit

    2015-01-01

    Aims The present study investigated the surface properties and murine pre-osteoblast cell (MC3T3-E1) responses of phosphoric acid (H3PO4) treated commercially pure titanium. Methods Titanium discs were treated with various concentration of H3PO4 (5%, 10%, and 20%; v/v) at 90 °C for 30 min. Surface properties were evaluated by profilometer, contact angle meter, and scanning electron microscopy (SEM) with energy dispersive X-rays. MC3T3-E1 attachment and spreading were evaluated by SEM and phalloidin immunohistochemistry staining. Results Surface roughness and wettability were not statistically difference among all experimental and control groups. Phosphate and oxygen were detected on H3PO4 treated surfaces. At 20 min, cell attachment was significantly higher in 10% and 20% H3PO4 treated groups compared to the control. Cells exhibited orientated-cytoskeleton fibers on 20% H3PO4 modified titanium surface. Though, there was no difference in cell spreading stage among all treatment groups. Conclusion H3PO4 treatment on titanium may influence early cell response, particularly on attachment and spreading. PMID:26937362

  16. Surface functionalities of gold nanoparticles impact embryonic gene expression responses

    PubMed Central

    Truong, Lisa; Tilton, Susan C.; Zaikova, Tatiana; Richman, Erik; Waters, Katrina M.; Hutchison, James E.; Tanguay, Robert L.

    2012-01-01

    Incorporation of gold nanoparticles (AuNPs) into consumer products is increasing; however, there is a gap in available toxicological data to determine the safety of AuNPs. In this study, we utilised the embryonic zebrafish to investigate how surface functionalisation and charge influence molecular responses. Precisely engineered AuNPs with 1.5 nm cores were synthesised and functionalized with three ligands: 2-mercaptoethanesulfonic acid (MES), N,N,N-trimethylammoniumethanethiol (TMAT), or 2-(2-(2-mercaptoethoxy)ethoxy)ethanol. Developmental assessments revealed differential biological responses when embryos were exposed to the functionalised AuNPs at the same concentration. Using inductively coupled plasma–mass spectrometry, AuNP uptake was confirmed in exposed embryos. Following exposure to MES- and TMAT-AuNPs from 6 to 24 or 6 to 48 h post fertilisation, pathways involved in inflammation and immune response were perturbed. Additionally, transport mechanisms were misregulated after exposure to TMAT and MES-AuNPs, demonstrating that surface functionalisation influences many molecular pathways. PMID:22263968

  17. Synthesis and surface properties of environmentally responsive segmented polyurethanes.

    PubMed

    Vaidya, Ashish; Chaudhury, Manoj K

    2002-05-01

    Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired. PMID:16290591

  18. Synthesis and surface properties of environmentally responsive segmented polyurethanes.

    PubMed

    Vaidya, Ashish; Chaudhury, Manoj K

    2002-05-01

    Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired.

  19. Transient Response of Rotor on Rolling-Element Bearings with Clearance

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Murphy, Brian T.; Sawicki, Jerzy T.; Poplawski, J. V.

    2006-01-01

    Internal clearance in rolling element bearings is usually present to allow for radial and axial growth of the rotor-bearing system and to accommodate bearing fit-up. The presence of this clearance also introduces a "dead band" into the load-deflection behavior of the bearing. Previous studies demonstrated that the presence of dead band clearance might have a significant effect on synchronous rotor response. In this work, the authors investigate transient response of a rotor supported on rolling element bearings with internal clearance. In addition, the stiffness of the bearings varies nonlinearly with bearing deflection and with speed. Bearing properties were accurately calculated with a state of the art rolling bearing analysis code. The subsequent rotordynamics analysis shows that for rapid acceleration rates the maximum response amplitude may be less than predicted by steady-state analysis. The presence of clearance may shift the critical speed location to lower speed values. The rotor vibration response exhibits subharmonic components which are more prominent with bearing clearance.

  20. Validation of an interferon stimulatory response element reporter gene assay for quantifying type I interferons.

    PubMed

    McCoski, S R; Xie, M; Hall, E B; Mercadante, P M; Spencer, T E; Lonergan, P; Ealy, A D

    2014-04-01

    The goal of this work was to develop a virus-free, cell-based interferon (IFN) bioassay and determine the utility of this assay on biological samples that contained IFN-τ, the trophoblast-secreted maternal recognition of pregnancy factor in ruminants. Madin-Darby bovine kidney cells were transduced with lentiviral particles that contained a firefly luciferase reporter construct driven by an IFN stimulatory response element (ISRE). Stably transduced cells were selected with the use of puromycin resistance. A linear, dose-responsive response was detected with human IFN-α and ovine IFN-τ. Interferon activity was detected in conditioned media from bovine trophoblast cells and uterine flushes collected from sheep and cattle. Activity also was detected in media collected after individual or small group culture of in vitro-produced bovine blastocysts at day 8 to 10 after fertilization. In summary, this IFN stimulatory response element-reporter assay may be used as an alternative to virus-dependent, cytopathic assays. It contains a similar sensitivity to IFNs and can be completed in a shorter time than cytopathic assays and does not require heightened biosafety conditions after cell transduction.

  1. Novel regulation of cardiac force-frequency relation by CREM (cAMP response element modulator).

    PubMed

    Isoda, Takayoshi; Paolocci, Nazareno; Haghighi, Kobra; Wang, Congrong; Wang, Yibin; Georgakopoulos, Dimitrios; Servillo, Giuseppe; Della Fazia, Maria Agnese; Kranias, Evangelia G; Depaoli-Roach, Anna A; Sassone-Corsi, Paolo; Kass, David A

    2003-02-01

    The cAMP response element modulator (CREM) plays pivotal roles in the hypothalamic-pituitary-gonadal axis. CREM mRNA is robustly expressed in human myocardium, and identified isoforms may suppress cAMP response element-mediated transcription. However, little is known about the physiological importance of CREM in intact hearts remains unknown. We studied CREM-null mice and age-matched control littermates by in vivo pressure-volume loops to analyze basal and reserve cardiac function. Basal systolic and diastolic function, echocardiographic morphology, and myocardial histology were normal in CREM-null animals. However functional reserve with increasing heart rate was markedly depressed, with less contractile augmentation (+22+/-9% CREM-/- vs.+62+/-11% controls, P<0.05) and relaxation shortening (5+/-5% CREM-/- vs. -18+/-3% controls; P<0.05) at faster rates. In contrast, isoproterenol dose-responses were similar, suggesting normal beta-adrenergic receptor-coupled signaling. Gene expression of calcium handling proteins (SERCA, phospholamban) and stress-response genes (e.g., alpha-skeletal actin, beta-myosin heavy chain, natriuretic peptides) were similar between groups. However, total and serine-phosphorylated phospholamban protein declined -38 and -64% respectively, and protein phosphatase-1 (PP1) activity increased 44% without increased protein levels (all P<0.01) in CREM-/- vs. controls. These results demonstrate novel involvement of CREM in regulation of PP1 activity and of PLB, likely resulting in a potent frequency-dependent influence on cardiac function.

  2. Identification of a cyclic-AMP-responsive element within the rat somatostatin gene.

    PubMed Central

    Montminy, M R; Sevarino, K A; Wagner, J A; Mandel, G; Goodman, R H

    1986-01-01

    We have examined the regulation of somatostatin gene expression by cAMP in PC12 rat pheochromocytoma cells transfected with the rat somatostatin gene. Forskolin at 10 microM caused a 4-fold increase in somatostatin mRNA levels within 4 hr of treatment in stably transfected cells. Chimeric genes containing the somatostatin gene promoter fused to the bacterial reporter gene encoding chloramphenicol acetyltransferase were also induced by cAMP in PC12 cells. To delineate the sequences required for response to cAMP, we constructed a series of promoter deletion mutants. Our studies defined a region between 60 and 29 base pairs upstream from the transcriptional initiation site that conferred cAMP responsiveness when placed adjacent to the simian virus 40 promoter. Within the cAMP-responsive element of the somatostatin gene, we observed an 8-base palindrome, 5'-TGACGTCA-3', which is highly conserved in many other genes whose expression is regulated by cAMP. cAMP responsiveness was greatly reduced when the somatostatin fusion genes were transfected into the mutant PC12 line A126-1B2, which is deficient in cAMP-dependent protein kinase 2. Our studies indicate that transcriptional regulation of the somatostatin gene by cAMP requires protein kinase 2 activity and may depend upon a highly conserved promoter element. Images PMID:2875459

  3. Designing Responsive Buckled Surfaces by Halftone Gel Lithography

    NASA Astrophysics Data System (ADS)

    Kim, Jungwook; Hanna, James A.; Byun, Myunghwan; Santangelo, Christian D.; Hayward, Ryan C.

    2012-03-01

    Self-actuating materials capable of transforming between three-dimensional shapes have applications in areas as diverse as biomedicine, robotics, and tunable micro-optics. We introduce a method of photopatterning polymer films that yields temperature-responsive gel sheets that can transform between a flat state and a prescribed three-dimensional shape. Our approach is based on poly(N-isopropylacrylamide) copolymers containing pendent benzophenone units that allow cross-linking to be tuned by irradiation dose. We describe a simple method of halftone gel lithography using only two photomasks, wherein highly cross-linked dots embedded in a lightly cross-linked matrix provide access to nearly continuous, and fully two-dimensional, patterns of swelling. This method is used to fabricate surfaces with constant Gaussian curvature (spherical caps, saddles, and cones) or zero mean curvature (Enneper’s surfaces), as well as more complex and nearly closed shapes.

  4. Rare earth elements tracing the soil erosion processes on slope surface under natural rainfall.

    PubMed

    Zhu, Mingyong; Tan, Shuduan; Dang, Haishan; Zhang, Quanfa

    2011-12-01

    A field experiment using rare earth elements (REEs) as tracers was conducted to investigate soil erosion processes on slope surfaces during rainfall events. A plot of 10m×2m×0.16m with a gradient of 20° (36.4%) was established and the plot was divided into two layers and four segments. Various REE tracers were applied to the different layers and segments to determine sediment dynamics under natural rainfall. Results indicated that sheet erosion accounted for more than 90% of total erosion when the rainfall amount and density was not large enough to generate concentrated flows. Sediment source changed in different sections on the slope surface, and the primary sediment source area tended to move upslope as erosion progressed. In rill erosion, sediment discharge mainly originated from the toe-slope and moved upwards as erosion intensified. The results obtained from this study suggest that multi-REE tracer technique is valuable in understanding the erosion processes and determining sediment sources. PMID:21839555

  5. Rare earth elements tracing the soil erosion processes on slope surface under natural rainfall.

    PubMed

    Zhu, Mingyong; Tan, Shuduan; Dang, Haishan; Zhang, Quanfa

    2011-12-01

    A field experiment using rare earth elements (REEs) as tracers was conducted to investigate soil erosion processes on slope surfaces during rainfall events. A plot of 10m×2m×0.16m with a gradient of 20° (36.4%) was established and the plot was divided into two layers and four segments. Various REE tracers were applied to the different layers and segments to determine sediment dynamics under natural rainfall. Results indicated that sheet erosion accounted for more than 90% of total erosion when the rainfall amount and density was not large enough to generate concentrated flows. Sediment source changed in different sections on the slope surface, and the primary sediment source area tended to move upslope as erosion progressed. In rill erosion, sediment discharge mainly originated from the toe-slope and moved upwards as erosion intensified. The results obtained from this study suggest that multi-REE tracer technique is valuable in understanding the erosion processes and determining sediment sources.

  6. X-ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros

    NASA Astrophysics Data System (ADS)

    Nittler, L. R.; Starr, R. D.; Lim, L.; McCoy, T. J.; Burbine, T. H.; Reedy, R. C.; Trombka, J. I.; Gorenstein, P.; Squyres, S. W.; Boynton, W. V.; McClanahan, T. P.; Bhangoo, J. S.; Clark, P. E.; Murphy, M. E.; Killen, R.

    2001-12-01

    We report major element ratios determined for the S-class asteroid 433 Eros using remote-sensing x-ray fluorescence spectroscopy with the near-Earth asteroid rendezvous Shoemaker x-ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended "quiet Sun" periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact-induced volatilization and/or photo- or ion-induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS-rich partial melt. Size-sorting processes could lead to segregation of Fe-Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x-ray spectrometer are not representative of the bulk Eros composition.

  7. A thermographic approach for surface crack depth evaluation through 3D finite element modeling

    NASA Astrophysics Data System (ADS)

    Basheer, Mohammed; PV, Nithin; Ravindran, Parag; Balasubramaniam, Krishnan

    2015-03-01

    Laser Thermography has been reported earlier by several researchers as a tool for detecting surface breaking cracks in metals. A high energy laser (pulsed Nd-YAG) was used to produce a highly localized thermal spot from which heat diffuses (predominantly) in the radial direction. The crack that is perpendicular to the surface and close to this thermal spot will perturb the lateral heat flow and this disturbance can be observed by an IR camera. The laser spot is then scanned over a region to map the crack; this allows remote imaging of crack morphology even in elevated temperatures. The present study involves a 3D finite element simulation using COMSOL Multiphysics as a tool to simulate the thermal flow from a pulsed laser source in the proximity of a crack. The modeling helped to understand the various parameters affecting the thermal images of laser heated spots. The influence of depth of the crack on temperature changes across the crack and the relationship between crack depth and temperature changes due to the crack was simulated and subsequently validated experimentally.

  8. The sensitivity of biological finite element models to the resolution of surface geometry: a case study of crocodilian crania

    PubMed Central

    Evans, Alistair R.; McHenry, Colin R.

    2015-01-01

    The reliability of finite element analysis (FEA) in biomechanical investigations depends upon understanding the influence of model assumptions. In producing finite element models, surface mesh resolution is influenced by the resolution of input geometry, and influences the resolution of the ensuing solid mesh used for numerical analysis. Despite a large number of studies incorporating sensitivity studies of the effects of solid mesh resolution there has not yet been any investigation into the effect of surface mesh resolution upon results in a comparative context. Here we use a dataset of crocodile crania to examine the effects of surface resolution on FEA results in a comparative context. Seven high-resolution surface meshes were each down-sampled to varying degrees while keeping the resulting number of solid elements constant. These models were then subjected to bite and shake load cases using finite element analysis. The results show that incremental decreases in surface resolution can result in fluctuations in strain magnitudes, but that it is possible to obtain stable results using lower resolution surface in a comparative FEA study. As surface mesh resolution links input geometry with the resulting solid mesh, the implication of these results is that low resolution input geometry and solid meshes may provide valid results in a comparative context. PMID:26056620

  9. The sensitivity of biological finite element models to the resolution of surface geometry: a case study of crocodilian crania.

    PubMed

    McCurry, Matthew R; Evans, Alistair R; McHenry, Colin R

    2015-01-01

    The reliability of finite element analysis (FEA) in biomechanical investigations depends upon understanding the influence of model assumptions. In producing finite element models, surface mesh resolution is influenced by the resolution of input geometry, and influences the resolution of the ensuing solid mesh used for numerical analysis. Despite a large number of studies incorporating sensitivity studies of the effects of solid mesh resolution there has not yet been any investigation into the effect of surface mesh resolution upon results in a comparative context. Here we use a dataset of crocodile crania to examine the effects of surface resolution on FEA results in a comparative context. Seven high-resolution surface meshes were each down-sampled to varying degrees while keeping the resulting number of solid elements constant. These models were then subjected to bite and shake load cases using finite element analysis. The results show that incremental decreases in surface resolution can result in fluctuations in strain magnitudes, but that it is possible to obtain stable results using lower resolution surface in a comparative FEA study. As surface mesh resolution links input geometry with the resulting solid mesh, the implication of these results is that low resolution input geometry and solid meshes may provide valid results in a comparative context.

  10. Effect of design selection on response surface performance

    NASA Technical Reports Server (NTRS)

    Carpenter, William C.

    1993-01-01

    Artificial neural nets and polynomial approximations were used to develop response surfaces for several test problems. Based on the number of functional evaluations required to build the approximations and the number of undetermined parameters associated with the approximations, the performance of the two types of approximations was found to be comparable. A rule of thumb is developed for determining the number of nodes to be used on a hidden layer of an artificial neural net and the number of designs needed to train an approximation is discussed.

  11. Broadband multiple responses of surface modes in quasicrystalline plasmonic structure

    PubMed Central

    Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

    2016-01-01

    We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

  12. Broadband multiple responses of surface modes in quasicrystalline plasmonic structure.

    PubMed

    Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

    2016-01-01

    We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

  13. Response Surface Analysis of Crowd Dynamics during Tawaf

    NASA Astrophysics Data System (ADS)

    Zarita, Zainuddin; Lim Eng, Aik

    2012-07-01

    A refined cellular automata model is applied to simulate the crowd movement of Muslim pilgrims performing the Tawaf ritual within the Al-Haram Mosque in Mecca. The results from the simulation are obtained and the influence of the predictor variables of the evacuation process (pedestrian flow and Tawaf duration) on the responses (pedestrian density, average walking speed, and cumulative evacuee) is investigated using response surface methodology (RSM). The average results from the experiments with an rms error less than 0.5 are obtained from the RSM. Its performance indicates that the RSM possesses excellent predictive ability for the model evacuation study, because both the experimental and the predicted values agree well with the results obtained in this study.

  14. Analysis of Resonance Response Performance of C-Band Antenna Using Parasitic Element

    PubMed Central

    Islam, M. T.; Misran, N.; Mandeep, J. S.

    2014-01-01

    Analysis of the resonance response improvement of a planar C-band (4–8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency. PMID:24895643

  15. Analysis of resonance response performance of C-band antenna using parasitic element.

    PubMed

    Zaman, M R; Islam, M T; Misran, N; Mandeep, J S

    2014-01-01

    Analysis of the resonance response improvement of a planar C-band (4-8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency. PMID:24895643

  16. Optimum Design of a Helicopter Rotor for Low Vibration Using Aeroelastic Analysis and Response Surface Methods

    NASA Astrophysics Data System (ADS)

    Ganguli, R.

    2002-11-01

    An aeroelastic analysis based on finite elements in space and time is used to model the helicopter rotor in forward flight. The rotor blade is represented as an elastic cantilever beam undergoing flap and lag bending, elastic torsion and axial deformations. The objective of the improved design is to reduce vibratory loads at the rotor hub that are the main source of helicopter vibration. Constraints are imposed on aeroelastic stability, and move limits are imposed on the blade elastic stiffness design variables. Using the aeroelastic analysis, response surface approximations are constructed for the objective function (vibratory hub loads). It is found that second order polynomial response surfaces constructed using the central composite design of the theory of design of experiments adequately represents the aeroelastic model in the vicinity of the baseline design. Optimization results show a reduction in the objective function of about 30 per cent. A key accomplishment of this paper is the decoupling of the analysis problem and the optimization problems using response surface methods, which should encourage the use of optimization methods by the helicopter industry.

  17. Effect of vitamin and trace-element supplementation on immune responses and infection in elderly subjects.

    PubMed

    Chandra, R K

    1992-11-01

    Ageing is associated with impaired immune responses and increased infection-related morbidity. This study assessed the effect of physiological amounts of vitamins and trace elements on immunocompetence and occurrence of infection-related illness. 96 independently living, healthy elderly individuals were randomly assigned to receive nutrient supplementation or placebo. Nutrient status and immunological variables were assessed at baseline and at 12 months, and the frequency of illness due to infection was ascertained. Subjects in the supplement group had higher numbers of certain T-cell subsets and natural killer cells, enhanced proliferation response to mitogen, increased interleukin-2 production, and higher antibody response and natural killer cell activity. These subjects were less likely than those in the placebo group to have illness due to infections (mean [SD] 23 [5] vs 48 [7] days per year, p = 0.002). Supplementation with a modest physiological amount of micronutrients improves immunity and decreases the risk of infection in old age.

  18. Planetary boundary layer response to surface temperature anomalies forcing

    NASA Astrophysics Data System (ADS)

    Perrot, Xavier; Lapeyre, Guillaume; Plougonven, Riwal

    2015-04-01

    Recent studies showed that strong sea surface temperature (SST) fronts, on the scale of the western boundary currents, strongly affect the planetary boundary layer (PBL) but also all the troposphere. This renewed the interest of air-sea interactions at oceanic meso-scales. Mainly two mechanisms are proposed in the literature, the first one (due to Wallace et al 1989) is based on the destabilization of the PBL above SST anomalies, the second one (Lindzen and Nigam 1987) is based on the pressure anomalies linked to the atmosphere temperature adjustment to the SST. These two mechanisms predict different responses of the PBL to the SST. We did numerical simulations with a meso-scale atmospheric model (WRF) with the same configuration as the one described in Lambert et al 2013. The model is forced by a SST anomaly which is first a zonally or meridionally constant field and secondly a field of meso-scale structures. Firstly we studied the influence of the initial wind strength on the PBL response for the two different types of SST anomalies. We showed that the dominant mechanism can change according to weak or strong wind and to the orientation of the SST anomaly. Secondly after considering a dry atmosphere we switched on the humidity in our configuration. We studied how it influences the PBL response and whether the mechanism driving the PBL response is still the same as in the dry case.

  19. Effects of rare earth elements and REE-binding proteins on physiological responses in plants.

    PubMed

    Liu, Dongwu; Wang, Xue; Chen, Zhiwei

    2012-02-01

    Rare earth elements (REEs), which include 17 elements in the periodic table, share chemical properties related to a similar external electronic configuration. REEs enriched fertilizers have been used in China since the 1980s. REEs could enter the cell and cell organelles, influence plant growth, and mainly be bound with the biological macromolecules. REE-binding proteins have been found in some plants. In addition, the chlorophyll activities and photosynthetic rate can be regulated by REEs. REEs could promote the protective function of cell membrane and enhance the plant resistance capability to stress produced by environmental factors, and affect the plant physiological mechanism by regulating the Ca²⁺ level in the plant cells. The focus of present review is to describe how REEs and REE-binding proteins participate in the physiological responses in plants.

  20. Identification of peroxisome-proliferator responsive element in the mouse HSL gene

    SciTech Connect

    Yajima, Hiroaki . E-mail: hyajima@kirin.co.jp; Kobayashi, Yumie; Kanaya, Tomoka; Horino, Yoko

    2007-01-12

    Hormone-sensitive lipase (HSL) catalyzes the rate-limiting step of lipolysis in adipose tissue. Several studies suggest that protein phosphorylation regulates the HSL enzymatic activity. On the other hand, the precise mechanism of the transcriptional regulation of the HSL gene remains to be elucidated. Here, we identified a functional peroxisome-proliferator responsive element (PPRE) in the mouse HSL promoter by reporter assay in CV-1 cells using serial deletion and point mutants of the 5'-flanking region. Chromatin immunoprecipitation (ChIP) analysis revealed that both peroxisome-proliferator activated receptor (PPAR{gamma}) and retinoid X receptor (RXR{alpha}) interacted with the region. Binding of the PPAR{gamma}/RXR{alpha} heterodimer to the PPRE sequence was also confirmed by electrophoretic mobility shift assay. These results indicate that the HSL gene is transcriptionally regulated by PPAR{gamma}/RXR{alpha} heterodimer, and suggest that a cis-acting element regulates the HSL gene expression.

  1. Finite element simulation of rate-dependent magneto-active polymer response

    NASA Astrophysics Data System (ADS)

    Haldar, K.; Kiefer, B.; Menzel, A.

    2016-10-01

    This contribution is concerned with the embedding of constitutive relations for magneto-active polymers (MAP) into finite element simulations. To this end, a recently suggested, calibrated, and validated material model for magneto-mechanically coupled and rate-dependent MAP response is briefly summarized in its continuous and algorithmic settings. Moreover, the strongly coupled field equations of finite deformation magneto-mechanics are reviewed. For the purpose of numerical simulation, a finite element model is then established based on the usual steps of weak form representation, discretization and consistent linearization. Two verifying inhomogeneous numerical examples are presented in which a classical ‘plate with a hole’ geometry is equipped with MAP properties and subjected to different types of time-varying mechanical and magnetic loading.

  2. Three-Dimensional Finite Element Ablative Thermal Response and Thermostructural Design of Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Dec, John A.; Braun, Robert D.

    2011-01-01

    A finite element ablation and thermal response program is presented for simulation of three-dimensional transient thermostructural analysis. The three-dimensional governing differential equations and finite element formulation are summarized. A novel probabilistic design methodology for thermal protection systems is presented. The design methodology is an eight step process beginning with a parameter sensitivity study and is followed by a deterministic analysis whereby an optimum design can determined. The design process concludes with a Monte Carlo simulation where the probabilities of exceeding design specifications are estimated. The design methodology is demonstrated by applying the methodology to the carbon phenolic compression pads of the Crew Exploration Vehicle. The maximum allowed values of bondline temperature and tensile stress are used as the design specifications in this study.

  3. Identification of peroxisome-proliferator responsive element in the mouse HSL gene.

    PubMed

    Yajima, Hiroaki; Kobayashi, Yumie; Kanaya, Tomoka; Horino, Yoko

    2007-01-12

    Hormone-sensitive lipase (HSL) catalyzes the rate-limiting step of lipolysis in adipose tissue. Several studies suggest that protein phosphorylation regulates the HSL enzymatic activity. On the other hand, the precise mechanism of the transcriptional regulation of the HSL gene remains to be elucidated. Here, we identified a functional peroxisome-proliferator responsive element (PPRE) in the mouse HSL promoter by reporter assay in CV-1 cells using serial deletion and point mutants of the 5'-flanking region. Chromatin immunoprecipitation (ChIP) analysis revealed that both peroxisome-proliferator activated receptor (PPARgamma) and retinoid X receptor (RXRalpha) interacted with the region. Binding of the PPARgamma/RXRalpha heterodimer to the PPRE sequence was also confirmed by electrophoretic mobility shift assay. These results indicate that the HSL gene is transcriptionally regulated by PPARgamma/RXRalpha heterodimer, and suggest that a cis-acting element regulates the HSL gene expression.

  4. Postural responses triggered by multidirectional leg lifts and surface tilts.

    PubMed

    Hughey, Lucinda K; Fung, Joyce

    2005-08-01

    The aim of the present study was to investigate the relationship between proactive and reactive components of postural control. We contrasted the kinematic and electromyographic (EMG) responses to multidirectional voluntary leg lifts with those elicited by unexpected surface tilts. In particular, we addressed the role of trunk stabilization following either a voluntary or forced weight shift from double to single limb support. Nine young female subjects stood with a standing posture of 45 degrees toe-out and their arms abducted to shoulder level. On the experimenter's signal, subjects either (1) lifted one leg as fast as possible in one of six directions (R/L side, R/L diagonal front, R/L diagonal back) to a height of 45 degrees or (2) maintained standing as the support surface tilted at a rate of 53 degrees /s to a height of 10 degrees in one of six directions (R/L-up, R/L diagonal toes-up, R/L diagonal toes-down). For both tasks, our results showed that the center of pressure (COP) displacement began before or in conjunction with displacement of the center of mass (COM), after which the COP oscillated about the horizontal projection of the COM. In addition, the muscles were recruited in a distal-to-proximal sequence, either in anticipation of the voluntary leg lift or in response to the sudden surface tilt. Thus, the COP was being used dynamically to control displacement of the COM. The axial postural strategy comprising head, trunk, and pelvis movements was quantified by means of principal component analysis. More than 95% of the variance in the data could be described by the first two eigenvectors, which revealed specific coordination patterns dominated by pelvis rotation in one direction and head/trunk rotation in the opposite direction. Unexpected surface tilting elicited an automatic response strategy that focused on controlling the orientation of the head and trunk with respect to the vertical gravity vector while trunk verticality was compromised for

  5. Elemental analysis of powders with surface-assisted thin film laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Cheung, Hoi Ching; Zheng, Ronger; Ma, Qianli; Chen, Yanping; Delepine-Gilon, Nicole; Yu, Jin

    2016-10-01

    We have developed in this work a method of elemental analysis of powdered materials with laser-induced breakdown spectroscopy (LIBS). This method requires simple sample preparation. Powders are first mixed into a 75 cSt base oil to obtain a paste which is then smeared onto the polished surface of a solid state substrate, aluminum plate for instance, in the form of a uniform thin film. The prepared sample is ablated by a high energy infrared (IR at 1064 nm) nanosecond laser pulse. The laser beam transmits through the coating layer of the material to be analyzed and induces a strong plasma from the substrate. The initial plasma interacts in turn with the coating layer, leading to the vaporization and excitation of the incorporated powder particles. The subsequent emission from the plasma includes emission lines of the elements contained in the powder, which is preferentially captured by a suitable detection system. The analysis of the recorded spectrum allows the concentration determination of the targeted elements in the powder. We first applied the method on a cellulose powder of 20 μm typical particle size. The powder was spiked with titanium dioxide (TiO2) nanoparticles for Ti concentrations ranging from 25 ppm to 5000 ppm by weight. Calibration graphs were thus built to deduce figures-of-merit parameters such as the coefficient of determination (R2) and the limits of detection and quantification (LoD and LoQ). We optimized especially the choice of reference line for spectrum normalization, which resulted in better analytical performances. In the second step, two sets of powders, the aforementioned cellulose powder and an alumina powder with average particle size of ≤ 10 μm, were spiked with TiO2 nanoparticles. We then assessed the matrix effect between these two different powders for the determination of Ti by comparing their calibration curves. Our results show universal calibration curve in Ti determination in the two tested matrices. The results are

  6. Sea-surface temperature reconstruction from trace elements variations of tropical coralline red algae

    NASA Astrophysics Data System (ADS)

    Darrenougue, Nicolas; De Deckker, Patrick; Eggins, Stephen; Payri, Claude

    2014-06-01

    We used laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to obtain high-resolution variations of the Mg/Ca, Sr/Ca and Li/Ca composition of free-living forms (i.e. rhodoliths) of the coralline red algal species Sporolithon durum in order to test their potential to archive seawater temperature information. A monitoring experiment was conducted based on alizarin red S (ARS) staining of rhodoliths specimens collected in various locations across a ˜1 km2 rhodolith bed in the vicinity of Nouméa, New Caledonia, where in situ temperature (IST) variations were recorded for 22 months between November 2009 and August 2011. A >45-year comparison of Mg and trace elements with sea-surface temperature (SST) was established from the analysis of 5 different branches belonging to three of the largest (7.4-8.5 cm in diameter) rhodolith specimens observed at the site. Consistent mean Mg/Ca, Sr/Ca and Li/Ca concentrations and seasonal patterns are found for the rhodoliths' last living years (2009-2011) across 43 branches and for the full 1963-2008 period across the 5 branches. Average elemental concentrations (Mg/Ca: 0.31 ± 0.04 mol/mol; Sr/Ca: 3.5 ± 0.4 mmol/mol and Li/Ca: 0.08 ± 0.02 mmol/mol) fall within range of those found in the literature. Individual element variations show good reproducibility between records and Mg/Ca, Sr/Ca and Li/Ca co-vary systematically. Combined records of Mg/Ca, Sr/Ca and Li/Ca are highly correlated with the IST monthly pattern for the 2009-2011 period (0.82 < r < 0.91; p < 0.001) and with local variations of monthly SST for the 1963-2008 period (0.65 < r < 0.85; p < 0.001), with Mg/Ca systematically being the best fit to monthly seawater temperature variations. Inter-annual Mg/Ca anomalies show significant correlation with the Oceanic Nino Index (ONI), indicating that S. durum rhodoliths also have the capacity to record the regional climate pattern in the tropical Pacific. Finally, consistent variations between the combined Mg

  7. Altered Response Hierarchy and Increased T-Cell Breadth upon HIV-1 Conserved Element DNA Vaccination in Macaques

    PubMed Central

    Kulkarni, Viraj; Valentin, Antonio; Rosati, Margherita; Alicea, Candido; Singh, Ashish K.; Jalah, Rashmi; Broderick, Kate E.; Sardesai, Niranjan Y.; Le Gall, Sylvie; Mothe, Beatriz; Brander, Christian; Rolland, Morgane; Mullins, James I.; Pavlakis, George N.; Felber, Barbara K.

    2014-01-01

    HIV sequence diversity and potential decoy epitopes are hurdles in the development of an effective AIDS vaccine. A DNA vaccine candidate comprising of highly conserved p24gag elements (CE) induced robust immunity in all 10 vaccinated macaques, whereas full-length gag DNA vaccination elicited responses to these conserved elements in only 5 of 11 animals, targeting fewer CE per animal. Importantly, boosting CE-primed macaques with DNA expressing full-length p55gag increased both magnitude of CE responses and breadth of Gag immunity, demonstrating alteration of the hierarchy of epitope recognition in the presence of pre-existing CE-specific responses. Inclusion of a conserved element immunogen provides a novel and effective strategy to broaden responses against highly diverse pathogens by avoiding decoy epitopes, while focusing responses to critical viral elements for which few escape pathways exist. PMID:24465991

  8. Evolutionary conservation of an atypical glucocorticoid-responsive element in the human tyrosine hydroxylase gene.

    PubMed

    Sheela Rani, C S; Soto-Pina, Alexandra; Iacovitti, Lorraine; Strong, Randy

    2013-07-01

    The human tyrosine hydroxylase (hTH) gene has a 42 bp evolutionarily conserved region designated (CR) II at -7.24 kb, which bears 93% homology to the region we earlier identified as containing the glucocorticoid response element, a 7 bp activator protein-1 (AP-1)-like motif in the rat TH gene. We cloned this hTH-CRII region upstream of minimal basal hTH promoter in luciferase (Luc) reporter vector, and tested glucocorticoid responsiveness in human cell lines. Dexamethasone (Dex) stimulated Luc activity of hTH-CRII in HeLa cells, while mifepristone, a glucocorticoid receptor (GR) antagonist, prevented Dex stimulation. Deletion of the 7 bp 5'-TGACTAA at -7243 bp completely abolished the Dex-stimulated Luc activity of hTH-CRII construct. The AP-1 agonist, tetradeconoyl-12,13-phorbol acetate (TPA), also stimulated hTH promoter activity, and Dex and TPA together further accentuated this response. Chromatin immunoprecipitation assays revealed the presence of both GR and AP-1 proteins, especially Jun family members, at this hTH promoter site. Dex did not stimulate hTH promoter activity in a catecholaminergic cell line, which had low endogenous GR levels, but did activate the response when GR was expressed exogenously. Thus, our studies have clearly identified a glucocorticoid-responsive element in a 7 bp AP-1-like motif in the promoter region at -7.24 kb of the human TH gene.

  9. Differential interactions of promoter elements in stress responses of the Arabidopsis Adh gene.

    PubMed Central

    Dolferus, R; Jacobs, M; Peacock, W J; Dennis, E S

    1994-01-01

    The Adh (alcohol dehydrogenase, EC 1.1.1.1.) gene from Arabidopsis thaliana (L.) Heynh. can be induced by dehydration and cold, as well as by hypoxia. A 1-kb promoter fragment (CADH: -964 to +53) is sufficient to confer the stress induction and tissue-specific developmental expression characteristics of the Adh gene to a beta-glucuronidase reporter gene. Deletion mapping of the 5' end and site-specific mutagenesis identified four regions of the promoter essential for expression under the three stress conditions. Some sequence elements are important for response to all three stress treatments, whereas others are stress specific. The most critical region essential for expression of the Arabidopsis Adh promoter under all three environmental stresses (region IV: -172 to -141) contains sequences homologous to the GT motif (-160 to -152) and the GC motif (-147 to -144) of the maize Adh1 anaerobic responsive element. Region III (-235 to -172) contains two regions shown by R.J. Ferl and B.H. Laughner ([1989] Plant Mol Biol 12: 357-366) to bind regulatory proteins; mutation of the G-box-1 region (5'-CCACGTGG-3', -216 to -209) does not affect expression under uninduced or hypoxic conditions, but significantly reduces induction by cold stress and, to a lesser extent, by dehydration stress. Mutation of the other G-box-like sequence (G-box-2: 5'-CCAAGTGG-3', -193 to -182) does not change hypoxic response and affects cold and dehydration stress only slightly. G-box-2 mutations also promote high levels of expression under uninduced conditions. Deletion of region I (-964 to -510) results in increased expression under uninduced and all stress conditions, suggesting that this region contains a repressor binding site. Region II (-510 to -384) contains a positive regulatory element and is necessary for high expression levels under all treatments. PMID:7972489

  10. Two approaches to form antibacterial surface: Doping with bactericidal element and drug loading

    NASA Astrophysics Data System (ADS)

    Sukhorukova, I. V.; Sheveyko, A. N.; Kiryukhantsev-Korneev, Ph. V.; Anisimova, N. Y.; Gloushankova, N. A.; Zhitnyak, I. Y.; Benesova, J.; Amler, E.; Shtansky, D. V.

    2015-03-01

    Two approaches (surface doping with bactericidal element and loading of antibiotic into specially formed surface microcontainers) to the fabrication of antibacterial yet biocompatible and bioactive surfaces are described. A network structure with square-shaped blind pores of 2.6 ± 0.6 × 10-3 mm3 for drug loading was obtained by selective laser sintering (SLS). The SLS-fabricated samples were loaded with 0.03, 0.3, 2.4, and 4 mg/cm2 of co-amoxiclav (amoxicillin and clavulanic acid). Ag-doped TiCaPCON films with 0.4, 1.2, and 4.0 at.% of Ag were obtained by co-sputtering of composite TiC0.5-Ca3(PO4)2 and metallic Ag targets. The surface structure of SLS-prepared samples and cross-sectional morphology of TiCaPCON-Ag films were studied by scanning electron microscopy. The through-thickness of Ag distribution in the TiCaPCON-Ag films was obtained by glow discharge optical emission spectroscopy. The kinetics of Ag ion release in normal saline solution was studied using inductively coupled plasma mass spectrometry. Bacterial activity of the samples was evaluated against S. epidermidis, S. aureus, and K. pneum. ozaenae using the agar diffusion test and photometric method by controlling the variation of optical density of the bacterial suspension over time. Cytocompatibility of the Ag-doped TiCaPCON films was observed in vitro using chondrocytic and MC3T3-E1 osteoblastic cells. The viability and proliferation of chondrocytic cells were determined using the MTS assay and PicoGreen assay tests, respectively. The alkaline phosphatase (ALP) activity of the SLS-fabricated samples loaded with co-amoxiclav was also studied. The obtained results showed that the moderate bacteriostatic effect of the Ag-doped TiCaPCON films is mainly manifested in the change of bacterial colony morphology and optical densities of bacteria suspensions. In contrast, the SLS-prepared samples showed a very rapid initial drug release resulting in strong bactericidal effect just from the start of the

  11. Rock-forming and rare elements in lunar surface material from the Sea of Tranquillity and the Ocean of Storms

    NASA Technical Reports Server (NTRS)

    Shevaleyevskiy, I. D.; Chupakhin, M. S.

    1974-01-01

    Methodological and analytical capabilities associated with spark mass spectrometry and X-ray spectroscopy are presented for the determination of the elemental composition of samples of lunar regolith returned to the earth by Apollo 11 and Apollo 12. Using X-ray spectroscopy, the main constituents of samples of lunar surface material were determined, and using mass spectrometry -- the main admixtures. The principal difference of Apollo 11 samples from Apollo 12 samples was found for elements contained in microconcentrations. This is especially true of rare earth elements.

  12. Cell-Based Assay for Identifying the Modulators of Antioxidant Response Element Signaling Pathway.

    PubMed

    Zhao, Jinghua; Shukla, Sunita J; Xia, Menghang

    2016-01-01

    The antioxidant response element (ARE) signaling pathway plays an important role in the amelioration of cellular oxidative stress. Thus, assays that detect this pathway can be useful for identifying chemicals that induce or inhibit oxidative stress signaling. The focus of this chapter is to describe a cell-based ARE assay in a quantitative high-throughput screening (qHTS) format to test a large collection of compounds that induce nuclear factor erythroid 2-related factor (Nrf2)/ARE signaling. The assay is described through cell handling, assay preparation, and instrument usage. PMID:27518623

  13. Transposable Elements Contribute to Activation of Maize Genes in Response to Abiotic Stress

    PubMed Central

    Makarevitch, Irina; Waters, Amanda J.; West, Patrick T.; Stitzer, Michelle; Hirsch, Candice N.; Ross-Ibarra, Jeffrey; Springer, Nathan M.

    2015-01-01

    Transposable elements (TEs) account for a large portion of the genome in many eukaryotic species. Despite their reputation as “junk” DNA or genomic parasites deleterious for the host, TEs have complex interactions with host genes and the potential to contribute to regulatory variation in gene expression. It has been hypothesized that TEs and genes they insert near may be transcriptionally activated in response to stress conditions. The maize genome, with many different types of TEs interspersed with genes, provides an ideal system to study the genome-wide influence of TEs on gene regulation. To analyze the magnitude of the TE effect on gene expression response to environmental changes, we profiled gene and TE transcript levels in maize seedlings exposed to a number of abiotic stresses. Many genes exhibit up- or down-regulation in response to these stress conditions. The analysis of TE families inserted within upstream regions of up-regulated genes revealed that between four and nine different TE families are associated with up-regulated gene expression in each of these stress conditions, affecting up to 20% of the genes up-regulated in response to abiotic stress, and as many as 33% of genes that are only expressed in response to stress. Expression of many of these same TE families also responds to the same stress conditions. The analysis of the stress-induced transcripts and proximity of the transposon to the gene suggests that these TEs may provide local enhancer activities that stimulate stress-responsive gene expression. Our data on allelic variation for insertions of several of these TEs show strong correlation between the presence of TE insertions and stress-responsive up-regulation of gene expression. Our findings suggest that TEs provide an important source of allelic regulatory variation in gene response to abiotic stress in maize. PMID:25569788

  14. A comparison of the effects of prosthetic and commercially pure metals on retrieved human fibroblasts: the role of surface elemental composition.

    PubMed

    Mostardi, R A; Kovacik, M W; Ramsier, R D; Bender, E T; Finefrock, J M; Bear, T F; Askew, M J

    2010-02-01

    The most common clinical cause of long-term failure in total joint replacement surgery is inflammatory aseptic osteolysis; a condition in which bone surrounding the prosthetic implant, and to which the implant is attached, is resorbed, rendering the artificial device loose and painful. Historically, the severity of this bone resorptive process has been thought to be predominately attributed to the size and shape of wear-debris particles, particularly the metallic particulates that interact biologically/immunologically with cells in the joint. Because the cytotoxic reactions are the result of interactions between the cells and the surfaces of the particulates, it is not clear in the realm of orthopedics to what extent different surface stoichiometric ratios contribute to instigating bioreactive or cytotoxic cellular responses that can lead to aseptic osteolysis. Using energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), this study presents data and analyses concerning the respective bulk and surface stoichiometric ratios of two commercially pure metal micro-particulates (tantalum and titanium), two prosthetic F75 cobalt-chromium-molybdenum alloy micro-particulates, and prosthetic F136 titanium-aluminum-vanadium alloy micro-particulates, each containing elements common to total joint replacement surgery. Cell culture viability data from four volunteer donors are also presented, which suggest that micro-particulates containing large percentages of surface titanium and aluminum can cause moderate cellular toxicity, and micro-particulates containing large percentages of surface cobalt can result in extremely severe cellular toxicity. This work further suggests that surface analysis techniques, such as XPS, are essential to determine surface elemental characterization of metallic materials prior to interpreting cellular response results.

  15. Cross-surface interface element for coupling built-up structural subdomains

    NASA Technical Reports Server (NTRS)

    Davila, C. G.; Ransom, J. B.; Aminpour, M. A.

    1994-01-01

    A new finite element for coupling built-up shell substructures is presented. The present work extends the hybrid variational formulation of the interface element developed by Aminpour and Ransom to permit coupling between two intersecting substructures. Designed for the assembly of independently built-up finite element models, this technique provides a level of modeling flexibility previously unavailable.

  16. Bioadsorption of rare earth elements through cell surface display of lanthanide binding tags

    DOE PAGESBeta

    Park, Dan M.; Reed, David W.; Yung, Mimi C.; Eslamimanesh, Ali; Lencka, Malgorzata M.; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E.; Navrotsky, Alexandra; Jiao, Yongqin

    2016-02-02

    In this study, with the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb3+ could be effectively recovered using citrate,more » consistent with thermodynamic speciation calculations that predicted strong complexation of Tb3+ by citrate. No reduction in Tb3+ adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.« less

  17. Manipulation of the closing transients of bileaflet mechanical heart valves using passive, surface-mounted elements

    NASA Astrophysics Data System (ADS)

    Simon, Helene

    2005-11-01

    The time-periodic closing of bileaflet mechanical heart valves is accompanied by a strong flow transient that is associated with the formation of a counter-rotating vortex pair near the b-datum line of leaflet edges. The strong transitory shear that is generated by these vortices may be damaging to blood elements and may result in platelet activation. In the present work, these flow transients are mitigated using miniature vortex generator arrays that are embedded on the surface of the leaflets. The closing transients in the absence and presence of the passive vortex generators are characterized using PIV measurements that are phase locked to the leaflet motion. The study utilizes a 25 mm St. Jude Medical valve placed in the aortic position of the Georgia Tech left heart simulator. The valve is subjected to physiological flow conditions: a heart rate of 70 bpm; a cardiac output of 5 l/min; and a mean aortic pressure of 90 mmHg. Measurements of the velocity field in the center plane of the leaflets demonstrate that the dynamics of the transient vortices that precede the formation of the leakage jets can be significantly altered and controlled by relatively simple passive modifications of existing valve designs.

  18. Mineral formation and redox-sensitive trace elements in a near-surface hydrothermal alteration system

    SciTech Connect

    Gehring, A.U. |; Schosseler, P.M.; Weidler, P.G.

    1999-07-01

    A recent hydrothermal mudpool at the southwestern slope of the Rincon de la Vieja volcano in Northwest Costa Rica exhibits an argillic alteration system formed by intense interaction of sulfuric acidic fluids with wall rock materials. Detailed mineralogical analysis revealed an assemblage with kaolinite, alunite, and opal-C as the major mineral phases. Electron paramagnetic resonance spectroscopy (EPR) showed 3 different redox-sensitive cations associated with the mineral phases, Cu{sup +} is structure-bound in opal-C, whereas VO{sup 2+} and Fe{sup 3+} are located in the kaolinite structure. The location of the redox-sensitive cations in different minerals of the assemblage is indicative of different chemical conditions. The formation of the alteration products can be described schematically as a 2-step process. In a first step alunite and opal-C were precipitated in a fluid with slightly reducing conditions and a low chloride availability. The second step is characterized by a decrease in K{sup +} activity and subsequent formation of kaolinite under weakly oxidizing to oxidizing redox conditions as indicated by structure-bound VO{sup 2+} and Fe{sup 3+}. The detection of paramagnetic trace elements structure-bound in mineral phases by EPR provide direct information about the prevailing redox conditions during alteration and can, therefore, be used as additional insight into the genesis of the hydrothermal, near-surface system.

  19. Bioadsorption of Rare Earth Elements through Cell Surface Display of Lanthanide Binding Tags.

    PubMed

    Park, Dan M; Reed, David W; Yung, Mimi C; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E; Navrotsky, Alexandra; Jiao, Yongqin

    2016-03-01

    With the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb(3+) could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb(3+) by citrate. No reduction in Tb(3+) adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation. PMID:26836847

  20. Bioadsorption of Rare Earth Elements through Cell Surface Display of Lanthanide Binding Tags.

    PubMed

    Park, Dan M; Reed, David W; Yung, Mimi C; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Fujita, Yoshiko; Riman, Richard E; Navrotsky, Alexandra; Jiao, Yongqin

    2016-03-01

    With the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb(3+) could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb(3+) by citrate. No reduction in Tb(3+) adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.

  1. Measurements of deuterium retention and surface elemental composition with double pulse laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Almaviva, Salvatore; Caneve, Luisa; Colao, Francesco; Maddaluno, Giorgio; Krawczyk, Natalia; Czarnecka, Agata; Gasior, Pawel; Kubkowska, Monica; Lepek, Michal

    2016-02-01

    Estimating the tritium amount retained in the plasma facing components and their surface layer composition is of crucial importance for ITER. Laser-induced breakdown spectroscopy (LIBS) is an analytical technique suitable for in situ measurements of both these quantities. For improving its sensitivity, the double pulse (DP) variant can be used, instead of the standard single pulse (SP). In this work Mo samples coated with 1.5-1.8 μm thick W-Al (as a proxy for Be) mixed layer, with co-deposited deuterium were analyzed under vacuum (˜5 × 10-5 mbar) by SP and DP LIBS, showing enhancement of the spectral intensity for the latter. Calibration free method was applied to the LIBS data for getting the elemental concentration of W and Al. Results are in satisfactory agreement with those obtained from preliminary, ion beam analysis measurements. Deuterium concentration was tentatively estimated by accounting for the intensity ratio between Dα and nearby WI lines.

  2. Bone char surface modification by nano-gold coating for elemental mercury vapor removal

    NASA Astrophysics Data System (ADS)

    Assari, Mohamad javad; Rezaee, Abbas; Rangkooy, Hossinali

    2015-07-01

    The present work was done to develop a novel nanocomposite using bone char coated with nano-gold for capture of elemental mercury (Hg0) from air. The morphologies, structures, and chemical constitute of the prepared nanocomposite were evaluated by UV-VIS-NIR, dynamic light-scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). The capture performance of nanocomposite was evaluated in a needle trap for mercury vapor. An on-line setup based on cold vapor atomic absorption spectrometry (CVAAS) was designed for Hg0 determination. Dynamic capacity of nanocomposite for Hg0 was shown high efficient operating capacity of 586.7 μg/g. As temperature increases, the dynamic adsorption capacity of the nanocomposite was decreased, which are characteristics of physicosorption processes. It was found that the surface modification of bone char with nano-gold has various advantages such as high operating dynamic adsorption capacity and low cost preparation. It was also demonstrated that the developed nanocomposite is suitable for on-line monitoring of Hg0. It could be applied for the laboratory and field studies.

  3. Blast response of curved carbon/epoxy composite panels: Experimental study and finite-element analysis

    NASA Astrophysics Data System (ADS)

    Phadnis, V. A.; Kumar, P.; Shukla, A.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    Experimental and numerical studies were conducted to understand the effect of plate curvature on blast response of carbon/epoxy composite panels. A shock-tube system was utilized to impart controlled shock loading to quasi-isotropic composite panels with differing range of radii of curvatures. A 3D Digital Image Correlation (DIC) technique coupled with high-speed photography was used to obtain out-of-plane deflection and velocity, as well as in-plane strain on the back face of the panels. Macroscopic post-mortem analysis was performed to compare yielding and deformation in these panels. A dynamic computational simulation that integrates fluid-structure interaction was conducted to evaluate the panel response in general purpose finite-element software ABAQUS/Explicit. The obtained numerical results were compared to the experimental data and showed a good correlation.

  4. A role for neuronal cAMP responsive-element binding (CREB)-1 in brain responses to calorie restriction

    PubMed Central

    Fusco, Salvatore; Ripoli, Cristian; Podda, Maria Vittoria; Ranieri, Sofia Chiatamone; Leone, Lucia; Toietta, Gabriele; McBurney, Michael W.; Schütz, Günther; Riccio, Antonella; Grassi, Claudio; Galeotti, Tommaso; Pani, Giovambattista

    2012-01-01

    Calorie restriction delays brain senescence and prevents neurodegeneration, but critical regulators of these beneficial responses other than the NAD+-dependent histone deacetylase Sirtuin-1 (Sirt-1) are unknown. We report that effects of calorie restriction on neuronal plasticity, memory and social behavior are abolished in mice lacking cAMP responsive-element binding (CREB)-1 in the forebrain. Moreover, CREB deficiency drastically reduces the expression of Sirt-1 and the induction of genes relevant to neuronal metabolism and survival in the cortex and hippocampus of dietary-restricted animals. Biochemical studies reveal a complex interplay between CREB and Sirt-1: CREB directly regulates the transcription of the sirtuin in neuronal cells by binding to Sirt-1 chromatin; Sirt-1, in turn, is recruited by CREB to DNA and promotes CREB-dependent expression of target gene peroxisome proliferator-activated receptor-γ coactivator-1α and neuronal NO Synthase. Accordingly, expression of these CREB targets is markedly reduced in the brain of Sirt KO mice that are, like CREB-deficient mice, poorly responsive to calorie restriction. Thus, the above circuitry, modulated by nutrient availability, links energy metabolism with neurotrophin signaling, participates in brain adaptation to nutrient restriction, and is potentially relevant to accelerated brain aging by overnutrition and diabetes. PMID:22190495

  5. A role for neuronal cAMP responsive-element binding (CREB)-1 in brain responses to calorie restriction.

    PubMed

    Fusco, Salvatore; Ripoli, Cristian; Podda, Maria Vittoria; Ranieri, Sofia Chiatamone; Leone, Lucia; Toietta, Gabriele; McBurney, Michael W; Schütz, Günther; Riccio, Antonella; Grassi, Claudio; Galeotti, Tommaso; Pani, Giovambattista

    2012-01-10

    Calorie restriction delays brain senescence and prevents neurodegeneration, but critical regulators of these beneficial responses other than the NAD(+)-dependent histone deacetylase Sirtuin-1 (Sirt-1) are unknown. We report that effects of calorie restriction on neuronal plasticity, memory and social behavior are abolished in mice lacking cAMP responsive-element binding (CREB)-1 in the forebrain. Moreover, CREB deficiency drastically reduces the expression of Sirt-1 and the induction of genes relevant to neuronal metabolism and survival in the cortex and hippocampus of dietary-restricted animals. Biochemical studies reveal a complex interplay between CREB and Sirt-1: CREB directly regulates the transcription of the sirtuin in neuronal cells by binding to Sirt-1 chromatin; Sirt-1, in turn, is recruited by CREB to DNA and promotes CREB-dependent expression of target gene peroxisome proliferator-activated receptor-γ coactivator-1α and neuronal NO Synthase. Accordingly, expression of these CREB targets is markedly reduced in the brain of Sirt KO mice that are, like CREB-deficient mice, poorly responsive to calorie restriction. Thus, the above circuitry, modulated by nutrient availability, links energy metabolism with neurotrophin signaling, participates in brain adaptation to nutrient restriction, and is potentially relevant to accelerated brain aging by overnutrition and diabetes. PMID:22190495

  6. Surface response of a viscoelastic medium to subsurface acoustic sources with application to medical diagnosis

    NASA Astrophysics Data System (ADS)

    Royston, Thomas J.; Yazicioglu, Yigit; Loth, Francis

    2003-02-01

    The response at the surface of an isotropic viscoelastic medium to buried fundamental acoustic sources is studied theoretically, computationally and experimentally. Finite and infinitesimal monopole and dipole sources within the low audible frequency range (40-400 Hz) are considered. Analytical and numerical integral solutions that account for compression, shear and surface wave response to the buried sources are formulated and compared with numerical finite element simulations and experimental studies on finite dimension phantom models. It is found that at low audible frequencies, compression and shear wave propagation from point sources can both be significant, with shear wave effects becoming less significant as frequency increases. Additionally, it is shown that simple closed-form analytical approximations based on an infinite medium model agree well with numerically obtained ``exact'' half-space solutions for the frequency range and material of interest in this study. The focus here is on developing a better understanding of how biological soft tissue affects the transmission of vibro-acoustic energy from biological acoustic sources below the skin surface, whose typical spectral content is in the low audible frequency range. Examples include sound radiated from pulmonary, gastro-intestinal and cardiovascular system functions, such as breath sounds, bowel sounds and vascular bruits, respectively.

  7. Maximization of fructose esters synthesis by response surface methodology.

    PubMed

    Neta, Nair Sampaio; Peres, António M; Teixeira, José A; Rodrigues, Ligia R

    2011-07-01

    Enzymatic synthesis of fructose fatty acid ester was performed in organic solvent media, using a purified lipase from Candida antartica B immobilized in acrylic resin. Response surface methodology with a central composite rotatable design based on five levels was implemented to optimize three experimental operating conditions (temperature, agitation and reaction time). A statistical significant cubic model was established. Temperature and reaction time were found to be the most significant parameters. The optimum operational conditions for maximizing the synthesis of fructose esters were 57.1°C, 100 rpm and 37.8 h. The model was validated in the identified optimal conditions to check its adequacy and accuracy, and an experimental esterification percentage of 88.4% (±0.3%) was obtained. These results showed that an improvement of the enzymatic synthesis of fructose esters was obtained under the optimized conditions. PMID:21356336

  8. Maximization of fructose esters synthesis by response surface methodology.

    PubMed

    Neta, Nair Sampaio; Peres, António M; Teixeira, José A; Rodrigues, Ligia R

    2011-07-01

    Enzymatic synthesis of fructose fatty acid ester was performed in organic solvent media, using a purified lipase from Candida antartica B immobilized in acrylic resin. Response surface methodology with a central composite rotatable design based on five levels was implemented to optimize three experimental operating conditions (temperature, agitation and reaction time). A statistical significant cubic model was established. Temperature and reaction time were found to be the most significant parameters. The optimum operational conditions for maximizing the synthesis of fructose esters were 57.1°C, 100 rpm and 37.8 h. The model was validated in the identified optimal conditions to check its adequacy and accuracy, and an experimental esterification percentage of 88.4% (±0.3%) was obtained. These results showed that an improvement of the enzymatic synthesis of fructose esters was obtained under the optimized conditions.

  9. Taste signaling elements expressed in gut enteroendocrine cells regulate nutrient-responsive secretion of gut hormones.

    PubMed

    Kokrashvili, Zaza; Mosinger, Bedrich; Margolskee, Robert F

    2009-09-01

    Many of the receptors and downstream signaling elements involved in taste detection and transduction are also expressed in enteroendocrine cells where they underlie the chemosensory functions of the gut. In one well-known example of gastrointestinal chemosensation (the "incretin effect"), it is known that glucose that is given orally, but not systemically, induces secretion of glucagon-like peptide 1 and glucose-dependent insulinotropic peptide (the incretin hormones), which in turn regulate appetite, insulin secretion, and gut motility. Duodenal L cells express sweet taste receptors, the taste G protein gustducin, and several other taste transduction elements. Knockout mice that lack gustducin or the sweet taste receptor subunit T1r3 have deficiencies in secretion of glucagon-like peptide 1 and glucose-dependent insulinotropic peptide and in the regulation of plasma concentrations of insulin and glucose in response to orally ingested carbohydrate-ie, their incretin effect is dysfunctional. Isolated small intestine and intestinal villi from gustducin null mice displayed markedly defective glucagon-like peptide 1 secretion in response to glucose, indicating that this is a local circuit of sugar detection by intestinal cells followed by hormone secretion from these same cells. Modulating hormone secretion from gut "taste cells" may provide novel treatments for obesity, diabetes, and malabsorption syndromes. PMID:19571229

  10. Receptors bound to antiprogestin from abortive complexes with hormone responsive elements.

    PubMed

    Guiochon-Mantel, A; Loosfelt, H; Ragot, T; Bailly, A; Atger, M; Misrahi, M; Perricaudet, M; Milgrom, E

    1988-12-15

    The mechanism of action of antisteroids is not understood and explanations of their antagonistic activity have been sought at all levels of hormone action. It has been proposed that antisteroids, after binding to receptor, trap it into a non-activated (non DNA-binding) form possibly through interaction with a heat-shock protein of relative molecular mass (Mr) 90,000 (90 K), or that the antisteroids provoke binding of receptor to nonspecific DNA sites but not to hormone responsive elements (HREs), or that the antisteroid-receptor complexes can bind to HREs but form abortive complexes that fail to regulate transcription. We have constructed a deleted cDNA encoding a mutant form of rabbit progesterone receptor which exhibits constitutive activity, that is, binds to HREs in the absence of hormone and thus bypasses the first two steps discussed above. Co-transfection experiments allowed the expression of both constitutive and wild-type receptors in the same recipient cells. Antiprogestin RU486-wild-type receptor complexes completely suppressed the activity of the constitutive receptor on a reporter gene, showing that the inhibition is at the level of their common responsive elements. PMID:3200320

  11. Mineralocorticoid receptor interaction with SP1 generates a new response element for pathophysiologically relevant gene expression

    PubMed Central

    Meinel, Sandra; Ruhs, Stefanie; Schumann, Katja; Strätz, Nicole; Trenkmann, Kay; Schreier, Barbara; Grosse, Ivo; Keilwagen, Jens; Gekle, Michael; Grossmann, Claudia

    2013-01-01

    The mineralocorticoid receptor (MR) is a ligand-induced transcription factor belonging to the steroid receptor family and involved in water-electrolyte homeostasis, blood pressure regulation, inflammation and fibrosis in the renocardiovascular system. The MR shares a common hormone-response-element with the glucocorticoid receptor but nevertheless elicits MR-specific effects including enhanced epidermal growth factor receptor (EGFR) expression via unknown mechanisms. The EGFR is a receptor tyrosine kinase that leads to activation of MAP kinases, but that can also function as a signal transducer for other signaling pathways. In the present study, we mechanistically investigate the interaction between a newly discovered MR- but not glucocorticoid receptor- responsive-element (=MRE1) of the EGFR promoter, specificity protein 1 (SP1) and MR to gain general insights into MR-specificity. Biological relevance of the interaction for EGFR expression and consequently for different signaling pathways in general is demonstrated in human, rat and murine vascular smooth muscle cells and cells of EGFR knockout mice. A genome-wide promoter search for identical binding regions followed by quantitative PCR validation suggests that the identified MR-SP1–MRE1 interaction might be applicable to other genes. Overall, a novel principle of MR-specific gene expression is explored that applies to the pathophysiologically relevant expression of the EGFR and potentially also to other genes. PMID:23821666

  12. Accuracy Assessment of Response Surface Approximations for Supersonic Turbine Design

    NASA Technical Reports Server (NTRS)

    Papila, Nilay; Papila, Melih; Shyy, Wei; Haftka, Raphael T.; FitzCoy, Norman

    2001-01-01

    There is a growing trend to employ CFD tools to supply the necessary information for design optimization of fluid dynamics components/systems. Such results are prone to uncertainties due to reasons including discretization. errors, incomplete convergence of computational procedures, and errors associated with physical models such as turbulence closures. Based on this type of information, gradient-based optimization algorithms often suffer from the noisy calculations, which can seriously compromise the outcome. Similar problems arise from the experimental measurements. Global optimization techniques, such as those based on the response surface (RS) concept are becoming popular in part because they can overcome some of these barriers. However, there are also fundamental issues related to such global optimization technique such as RS. For example, in high dimensional design spaces, typically only a small number of function evaluations are available due to computational and experimental costs. On the other hand, complex features of the design variables do not allow one to model the global characteristics of the design space with simple quadratic polynomials. Consequently a main challenge is to reduce the size of the region where we fit the RS, or make it more accurate in the regions where the optimum is likely to reside. Response Surface techniques using either polynomials or and Neural Network (NN) methods offer designers alternatives to conduct design optimization. The RS technique employs statistical and numerical techniques to establish the relationship between design variables and objective/constraint functions, typically using polynomials. In this study, we aim at addressing issues related to the following questions: (1) How to identify outliers associated with a given RS representation and improve the RS model via appropriate treatments? (2) How to focus on selected design data so that RS can give better performance in regions critical to design optimization? (3

  13. Understanding the biological responses of nanostructured metals and surfaces

    NASA Astrophysics Data System (ADS)

    Lowe, Terry C.; Reiss, Rebecca A.

    2014-08-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science.

  14. Stretch-dependent changes in surface profiles of the human crystalline lens during accommodation: A finite element study

    PubMed Central

    Pour, Hooman Mohammad; Kanapathipillai, Sangarapillai; Zarrabi, Khosrow; Manns, Fabrice; Ho, Arthur

    2015-01-01

    Background A nonlinear isotropic finite element (FE) model of a 29 year old human crystalline lens was constructed to study the effects of various geometrical parameters on lens accommodation. Methods The model simulates dis-accommodation by stretching of the lens and predicts the change in the lens capsule, cortex and nucleus surface profiles at select states of stretching/accommodation. Multiple regression analysis (MRA) is used to develop a stretch-dependent mathematical model relating the lens sagittal height to the radial position of the lens surface as a function of dis-accommodative stretch. A load analysis is performed to compare the FE results to empirical results from lens stretcher studies. Using the predicted geometrical changes, the optical response of the whole eye during accommodation was analysed by ray-tracing. Results Aspects of lens shape change relative to stretch were evaluated including change in diameter (d), central thickness (T) and accommodation (A). Maximum accommodation achieved was 10.29 D. From the MRA, the stretch-dependent mathematical model of the lens shape related lens curvatures as a function of lens ciliary stretch well (maximum mean-square residual error 2.5×10−3 µm, p<0.001). The results are compared with those from in vitro studies. Conclusions The FE and ray-tracing predictions are consistent with EVAS studies in terms of load and power change versus change in thickness. The mathematical stretch-dependent model of accommodation presented may have utility in investigating lens behaviour at states other than the relaxed or fully-accommodated states. PMID:25727940

  15. An interval model updating strategy using interval response surface models

    NASA Astrophysics Data System (ADS)

    Fang, Sheng-En; Zhang, Qiu-Hu; Ren, Wei-Xin

    2015-08-01

    Stochastic model updating provides an effective way of handling uncertainties existing in real-world structures. In general, probabilistic theories, fuzzy mathematics or interval analyses are involved in the solution of inverse problems. However in practice, probability distributions or membership functions of structural parameters are often unavailable due to insufficient information of a structure. At this moment an interval model updating procedure shows its superiority in the aspect of problem simplification since only the upper and lower bounds of parameters and responses are sought. To this end, this study develops a new concept of interval response surface models for the purpose of efficiently implementing the interval model updating procedure. The frequent interval overestimation due to the use of interval arithmetic can be maximally avoided leading to accurate estimation of parameter intervals. Meanwhile, the establishment of an interval inverse problem is highly simplified, accompanied by a saving of computational costs. By this means a relatively simple and cost-efficient interval updating process can be achieved. Lastly, the feasibility and reliability of the developed method have been verified against a numerical mass-spring system and also against a set of experimentally tested steel plates.

  16. Optimization of mead production using response surface methodology.

    PubMed

    Gomes, Teresa; Barradas, Carla; Dias, Teresa; Verdial, João; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M

    2013-09-01

    The main aim of the present work was to optimize mead production using Response Surface Methodology. The effects of temperature (x₁: 20-30°C) and nutrients concentration (x₂: 60-120g /hL) on mead quality, concerning the final concentrations of glucose (Y₁), fructose (Y₂), ethanol (Y₃), glycerol (Y₄) and acetic acid (Y₅), were studied. Twelve operational conditions were tested. No delays and moods were observed during fermentations. The second order polynomial models determined produced satisfactory fittings of the experimental data with regard to glucose (R²=0.646, p=0.001), ethanol (R²=0.741, p=0.049), glycerol (R²=0.899, p=0.002), fructose (R²=0.902, p=0.033) and acetic acid (R²=0.913, p=0.001). The optimum extraction conditions determined in order to maximize the combined responses were 24°C and a nutrients concentration of 0.88g/L. The mead produced under these conditions had the following characteristics: ethanol concentration of 10.2%, acetic acid 0.54 g/L, glycerol 7.8 g/L, glucose 1.8 g/L and fructose 2.5 g/L. These values were in agreement with the predicted and were within the safe limit established for acetic acid and the recommended range for glycerol. Furthermore, the residual sugars concentration was also low, decreasing the possibility of occurring undesirable refermentations.

  17. ROLE OF SURFACE FUNCTIONAL GROUPS IN THE CAPTURE OF ELEMENTAL MERCURY AND MERCURIC CHLORIDE BY ACTIVATED CARBONS

    EPA Science Inventory

    The paper discusses using a laboratory-scale, fixed bed apparatus to study the role of surface functional groups (SFGs) in the capture of mercuric chloride (HgC12) and elemental mercury (Hgo) in nitrogen (N2) prior to flue gas atmosphere studies. The study focused on two activat...

  18. The finite element absolute nodal coordinate formulation incorporated with surface stress effect to model elastic bending nanowires in large deformation

    NASA Astrophysics Data System (ADS)

    He, Jin; Lilley, Carmen M.

    2009-08-01

    Surface stress was incorporated into the finite element absolute nodal coordinate formulation in order to model elastic bending of nanowires in large deformation. The absolute nodal coordinate formulation is a numerical method to model bending structures in large deformation. The generalized Young-Laplace equation was employed to model the surface stress effect on bending nanowires. Effects from surface stress and large deformation on static bending nanowires are presented and discussed. The results calculated with the absolute nodal coordinate formulation incorporated with surface stress show that the surface stress effect makes the bending nanowires behave like softer or stiffer materials depending on the boundary condition. The surface stress effect diminishes as the dimensions of the bending structures increase beyond the nanoscale. The developed algorithm is consistent with the classical absolute nodal coordinate formulation at the macroscale.

  19. Capicua DNA-binding sites are general response elements for RTK signaling in Drosophila.

    PubMed

    Ajuria, Leiore; Nieva, Claudia; Winkler, Clint; Kuo, Dennis; Samper, Núria; Andreu, María José; Helman, Aharon; González-Crespo, Sergio; Paroush, Ze'ev; Courey, Albert J; Jiménez, Gerardo

    2011-03-01

    RTK/Ras/MAPK signaling pathways play key functions in metazoan development, but how they control expression of downstream genes is not well understood. In Drosophila, it is generally assumed that most transcriptional responses to RTK signal activation depend on binding of Ets-family proteins to specific cis-acting sites in target enhancers. Here, we show that several Drosophila RTK pathways control expression of downstream genes through common octameric elements that are binding sites for the HMG-box factor Capicua, a transcriptional repressor that is downregulated by RTK signaling in different contexts. We show that Torso RTK-dependent regulation of terminal gap gene expression in the early embryo critically depends on Capicua octameric sites, and that binding of Capicua to these sites is essential for recruitment of the Groucho co-repressor to the huckebein enhancer in vivo. We then show that subsequent activation of the EGFR RTK pathway in the neuroectodermal region of the embryo controls dorsal-ventral gene expression by downregulating the Capicua protein, and that this control also depends on Capicua octameric motifs. Thus, a similar mechanism of RTK regulation operates during subdivision of the anterior-posterior and dorsal-ventral embryonic axes. We also find that identical DNA octamers mediate Capicua-dependent regulation of another EGFR target in the developing wing. Remarkably, a simple combination of activator-binding sites and Capicua motifs is sufficient to establish complex patterns of gene expression in response to both Torso and EGFR activation in different tissues. We conclude that Capicua octamers are general response elements for RTK signaling in Drosophila.

  20. Detection of a functional xenobiotic response element in a widely employed FoxO-responsive reporter construct.

    PubMed

    Eckers, Anna; Sauerbier, Elisabeth; Anwar-Mohamed, Anwar; Hamann, Ingrit; Esser, Charlotte; Schroeder, Peter; El-Kadi, Ayman O S; Klotz, Lars-Oliver

    2011-12-15

    FHRE-Luc is a promoter reporter construct that is widely used to assess the activity of FoxO (forkhead box, class O) transcription factors. We here demonstrate that this promoter construct responds to exposure of HepG2 human hepatoma cells to known agonists of the aryl hydrocarbon receptor (AhR), 3-methylcholanthrene, benzo(a)pyrene, and 6-formylindolo[3,2-b]carbazole. However, FHRE-Luc activation did not coincide with FoxO DNA binding or changes in Akt-induced FoxO phosphorylation after treatment with AhR agonists. Testing FHRE-Luc deletion constructs and using AhR-deficient cells, we found that FHRE-Luc activation by AhR agonists is due to a functional xenobiotic-response element (XRE) spanning the backbone/insert border of the reporter plasmid. In conclusion, care must be taken when using FHRE-Luc to assess FoxO activity in response to stimuli that potentially interfere with xenobiotic signaling. PMID:22019820

  1. Involvement of cyclic-nucleotide response element-binding family members in the radiation response of Ramos B lymphoma cells.

    PubMed

    Di Nisio, Chiara; Sancilio, Silvia; Di Giacomo, Viviana; Rapino, Monica; Sancillo, Laura; Genovesi, Domenico; Di Siena, Alessandro; Rana, Rosa Alba; Cataldi, Amelia; Di Pietro, Roberta

    2016-01-01

    The aim of the present study was to investigate the role of Cyclic-nucleotide Response Element-Binding (CREB) family members and related nuclear transcription factors in the radiation response of human B lymphoma cell lines (Daudi and Ramos). Unlike the more radiosensitive Daudi cells, Ramos cells demonstrated only a moderate increase in early apoptosis after 3-5 Gy irradiation doses, which was detected with Annexin V/PI staining. Moreover, a significant and dose-dependent G2/M phase accumulation was observed in the same cell line at 24 h after both ionizing radiation (IR) doses. Western blot analysis showed an early increase in CREB protein expression that was still present at 3 h and more evident after 3 Gy IR in Ramos cells, along with the dose-dependent upregulation of p53 and NF-κB. These findings were consistent with real-time RT-PCR analysis that showed an early- and dose-dependent upregulation of NFKB1, IKBKB and XIAP gene expression. Unexpectedly, pre-treatment with SN50 did not increase cell death, but cell viability. Taken together, these findings let us hypothesise that the early induction and activation of NF-κB1 in Ramos cells could mediate necrotic cell death and be linked to other molecules belonging to CREB family and involved in the cell cycle regulation. PMID:26573110

  2. Use of postmortem temperature decay response surface plots of heat transport in the human eye to predict time of death.

    PubMed

    Smart, Jimmy L

    2014-03-01

    A finite element heat transfer model of the human eye was previously constructed and applied to experimental postmortem temperature decay curves collected in eyeballs of ten human bodies. The model was applied in the early postmortem period of 0–24 h under conditions of natural convection–radiation. Based upon this previous model, response surfaces for postmortem temperature decay were constructed based upon variable ranges of the natural convective–radiation heat transfer coefficient from 7–13 W/m2 K, ambient temperatures of 10–33°C, and times of 0–24 h. Mathematical equations to describe these response surfaces have been developed. This response surface method is demonstrated for use by coroners/medical personnel to estimate time of death from recorded field temperature data collected over a 30-min period. Sensitivity of the model to small changes in the key variable of ambient temperature is explored. The response surface model is applied to two cases of previously collected experimental eyeball temperature data. This response surface model method is only valid for constant surrounding temperatures, conditions of natural convection, no radiation effects, and postmortem times of 0–24 h.

  3. Application of response surface techniques to helicopter rotor blade optimization procedure

    NASA Technical Reports Server (NTRS)

    Henderson, Joseph Lynn; Walsh, Joanne L.; Young, Katherine C.

    1995-01-01

    In multidisciplinary optimization problems, response surface techniques can be used to replace the complex analyses that define the objective function and/or constraints with simple functions, typically polynomials. In this work a response surface is applied to the design optimization of a helicopter rotor blade. In previous work, this problem has been formulated with a multilevel approach. Here, the response surface takes advantage of this decomposition and is used to replace the lower level, a structural optimization of the blade. Problems that were encountered and important considerations in applying the response surface are discussed. Preliminary results are also presented that illustrate the benefits of using the response surface.

  4. Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

    SciTech Connect

    Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H PETER.

    2004-03-04

    Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam.

  5. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  6. Identifying surface response to drought and heat with a land surface model and NDVI

    NASA Astrophysics Data System (ADS)

    Harrison, L. S.; Michaelsen, J.; Funk, C. C.; Carvalho, L. V.; Still, C. J.; McNally, A.; Peters-Lidard, C. D.

    2012-12-01

    Lack of in situ observations makes drought monitoring a challenge in East Africa. Hence an effective means of identifying climate hazards and surface impacts are satellite-based rainfall estimates and vegetation observations. During the 2011 Kenyan drought Rainfall Estimation Algorithm Version 2 (RFE2.0) and expedited Moderate Resolution Imaging Spectroradiometer (eMODIS) NDVI products were used to delineate regional gradients of food insecurity, a critical factor in prompt distribution of aid. Land surface models (LSM) beckon as a means for expanding our understanding of drought. Modeled turbulent surface fluxes may make explicit physical processes responsible for observed plant stress. When sensible heating occurs under low evapotranspiration (AET) conditions, we would expect vegetation stress to increase. In this paper we examine two aspects of temperature-vegetation stress as interpreted by a LSM: (1) To what extent do sensible heating anomalies accompany AET anomalies and (2) how do rainfall and temperature influence energy partitioning? We investigate for the March-May rainy season (2001-12) across Kenya's rangelands at interannual and sub-seasonal timescales. Results highlight landscape characteristics with disproportionate sensitivity to climate. LSM estimates are compared to the vegetation response observed with NDVI. We establish the relationship between sources and use 2009 and 2011 agro-pastoral droughts as criteria for the LSM as a potential monitoring tool. Climate and flux data are from Noah3.2 LSM forced with RFE2.0 rainfall in a custom configuration of the NASA Land Information System. Satellite observations are from eMODIS NDVI.

  7. Finite-Element Modelling of the Response of the Gerbil Middle Ear to Sound.

    PubMed

    Maftoon, Nima; Funnell, W Robert J; Daniel, Sam J; Decraemer, Willem F

    2015-10-01

    We present a finite-element model of the gerbil middle ear that, using a set of baseline parameters based primarily on a priori estimates from the literature, generates responses that are comparable with responses we measured in vivo using multi-point vibrometry and with those measured by other groups. We investigated the similarity of numerous features (umbo, pars-flaccida and pars-tensa displacement magnitudes, the resonance frequency and break-up frequency, etc.) in the experimental responses with corresponding ones in the model responses, as opposed to simply computing frequency-by-frequency differences between experimental and model responses. The umbo response of the model is within the range of variability seen in the experimental data in terms of the low-frequency (i.e., well below the middle-ear resonance) magnitude and phase, the main resonance frequency and magnitude, and the roll-off slope and irregularities in the response above the resonance frequency, but is somewhat high for frequencies above the resonance frequency. At low frequencies, the ossicular axis of rotation of the model appears to correspond to the anatomical axis but the behaviour is more complex at high frequencies (i.e., above the pars-tensa break-up). The behaviour of the pars tensa in the model is similar to what is observed experimentally in terms of magnitudes, phases, the break-up frequency of the spatial vibration pattern, and the bandwidths of the high-frequency response features. A sensitivity analysis showed that the parameters that have the strongest effects on the model results are the Young's modulus, thickness and density of the pars tensa; the Young's modulus of the stapedial annular ligament; and the Young's modulus and density of the malleus. Displacements of the tympanic membrane and manubrium and the low-frequency displacement of the stapes did not show large changes when the material properties of the incus, stapes, incudomallear joint, incudostapedial joint, and

  8. Parametric comparisons of intracranial mechanical responses from three validated finite element models of the human head.

    PubMed

    Ji, Songbai; Ghadyani, Hamidreza; Bolander, Richard P; Beckwith, Jonathan G; Ford, James C; McAllister, Thomas W; Flashman, Laura A; Paulsen, Keith D; Ernstrom, Karin; Jain, Sonia; Raman, Rema; Zhang, Liying; Greenwald, Richard M

    2014-01-01

    A number of human head finite element (FE) models have been developed from different research groups over the years to study the mechanisms of traumatic brain injury. These models can vary substantially in model features and parameters, making it important to evaluate whether simulation results from one model are readily comparable with another, and whether response-based injury thresholds established from a specific model can be generalized when a different model is employed. The purpose of this study is to parametrically compare regional brain mechanical responses from three validated head FE models to test the hypothesis that regional brain responses are dependent on the specific head model employed as well as the region of interest (ROI). The Dartmouth Scaled and Normalized Model (DSNM), the Simulated Injury Monitor (SIMon), and the Wayne State University Head Injury Model (WSUHIM) were selected for comparisons. For model input, 144 unique kinematic conditions were created to represent the range of head impacts sustained by male collegiate hockey players during play. These impacts encompass the 50th, 95th, and 99th percentile peak linear and rotational accelerations at 16 impact locations around the head. Five mechanical variables (strain, strain rate, strain × strain rate, stress, and pressure) in seven ROIs reported from the FE models were compared using Generalized Estimating Equation statistical models. Highly significant differences existed among FE models for nearly all output variables and ROIs. The WSUHIM produced substantially higher peak values for almost all output variables regardless of the ROI compared to the DSNM and SIMon models (p < 0.05). DSNM also produced significantly different stress and pressure compared with SIMon for all ROIs (p < 0.05), but such differences were not consistent across ROIs for other variables. Regardless of FE model, most output variables were highly correlated with linear and rotational peak accelerations. The

  9. Parametric Comparisons of Intracranial Mechanical Responses from Three Validated Finite Element Models of the Human Head

    PubMed Central

    Ji, Songbai; Ghadyani, Hamidreza; Bolander, Richard P.; Beckwith, Jonathan G.; Ford, James C.; Mcallister, Thomas W.; Flashman, Laura A.; Paulsen, Keith D.; Ernstrom, Karin; Jain, Sonia; Raman, Rema; Zhang, Liying; Greenwald, Richard M.

    2015-01-01

    A number of human head finite element (FE) models have been developed from different research groups over the years to study the mechanisms of traumatic brain injury. These models can vary substantially in model features and parameters, making it important to evaluate whether simulation results from one model are readily comparable with another, and whether response-based injury thresholds established from a specific model can be generalized when a different model is employed. The purpose of this study is to parametrically compare regional brain mechanical responses from three validated head FE models to test the hypothesis that regional brain responses are dependent on the specific head model employed as well as the region of interest (ROI). The Dartmouth Scaled and Normalized Model (DSNM), the Simulated Injury Monitor (SIMon), and the Wayne State University Head Injury Model (WSUHIM) were selected for comparisons. For model input, 144 unique kinematic conditions were created to represent the range of head impacts sustained by male collegiate hockey players during play. These impacts encompass the 50th, 95th, and 99th percentile peak linear and rotational accelerations at 16 impact locations around the head. Five mechanical variables (strain, strain rate, strain × strain rate, stress, and pressure) in seven ROIs reported from the FE models were compared using Generalized Estimating Equation statistical models. Highly significant differences existed among FE models for nearly all output variables and ROIs. The WSUHIM produced substantially higher peak values for almost all output variables regardless of the ROI compared to the DSNM and SIMon models (p < 0.05). DSNM also produced significantly different stress and pressure compared with SIMon for all ROIs (p < 0.05), but such differences were not consistent across ROIs for other variables. Regardless of FE model, most output variables were highly correlated with linear and rotational peak accelerations. The

  10. Advanced Response Surface Modeling of Ares I Roll Control Jet Aerodynamic Interactions

    NASA Technical Reports Server (NTRS)

    Favaregh, Noah M.

    2010-01-01

    The Ares I rocket uses roll control jets. These jets have aerodynamic implications as they impinge on the surface and protuberances of the vehicle. The jet interaction on the body can cause an amplification or a reduction of the rolling moment produced by the jet itself, either increasing the jet effectiveness or creating an adverse effect. A design of experiments test was planned and carried out using computation fluid dynamics, and a subsequent response surface analysis ensued on the available data to characterize the jet interaction across the ascent portion of the Ares I flight envelope. Four response surface schemes were compared including a single response surface covering the entire design space, separate sector responses that did not overlap, continuously overlapping surfaces, and recursive weighted response surfaces. These surfaces were evaluated on traditional statistical metrics as well as visual inspection. Validation of the recursive weighted response surface was performed using additionally available data at off-design point locations.

  11. Optimization of sustained release aceclofenac microspheres using response surface methodology.

    PubMed

    Deshmukh, Rameshwar K; Naik, Jitendra B

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14±0.015% to 85.34±0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12h. The optimized microspheres formulation showed E.E. of 84.87±0.005 with small error value (1.39). The low magnitudes of error and the significant value of R(2) in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects.

  12. Identification of two novel functional p53 responsive elements in the Herpes Simplex Virus-1 genome

    PubMed Central

    Hsieh, Jui-Cheng; Kuta, Ryan; Armour, Courtney R.; Boehmer, Paul E.

    2014-01-01

    Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activation onto a heterologous reporter gene. Importantly, expression of the essential immediate early viral transactivator ICP4 and the essential DNA replication protein ICP8, that are adjacent to p53RE-S and p53RE-L, are repressed in a p53-dependent manner. Taken together, this study identifies two novel functional p53RE in the HSV-1 genome and suggests a complex mechanism of viral gene regulation by p53 which may determine progression of the lytic viral replication cycle or the establishment of latency. PMID:25010269

  13. Responses of Noccaea caerulescens and Lupinus albus in trace elements-contaminated soils.

    PubMed

    Martínez-Alcalá, Isabel; Hernández, Luis E; Esteban, Elvira; Walker, David J; Bernal, M Pilar

    2013-05-01

    Plants exposed to trace elements can suffer from oxidative stress, which is characterised by the accumulation of reactive oxygen species, alteration in the cellular antioxidant defence system and ultimately lipid peroxidation. We assessed the most-appropriate stress indexes to describe the response of two plant species, with different strategies for coping with trace elements (TEs), to particular contaminants. Noccaea caerulescens, a hyperaccumulator, and Lupinus albus, an excluder, were grown in three soils of differing pH: an acidic soil, a neutral soil (both contaminated mainly by Cu, Zn and As) and a control soil. Then, plant stress indicators were measured. As expected, N. caerulescens accumulated higher levels of Zn and Cd in shoots than L. albus, this effect being stronger in the acid soil, reflecting greater TE solubility in this soil. However, the shoot concentrations of Mn were higher in L. albus than in N. caerulescens, while the As concentration was similar in the two species. In L. albus, the phenolic content and lipid peroxidation were related with the Cu concentration, whereas the Zn and Cd concentrations in N. caerulescens were more closely related to glutathione content and lipid peroxidation. Interestingly, phytochelatins were only found in L. albus grown in polluted soils. Hence, the two species differed with respect to the TEs which provoked stress and the biochemical indicators of the stress, there being a close relationship between the accumulation of TEs and their associated stress indicators in the different plant organs.

  14. Formation of a Polycomb-Domain in the Absence of Strong Polycomb Response Elements

    PubMed Central

    De, Sandip; Mitra, Apratim; Cheng, Yuzhong; Pfeifer, Karl; Kassis, Judith A.

    2016-01-01

    Polycomb group response elements (PREs) in Drosophila are DNA-elements that recruit Polycomb proteins (PcG) to chromatin and regulate gene expression. PREs are easily recognizable in the Drosophila genome as strong peaks of PcG-protein binding over discrete DNA fragments; many small but statistically significant PcG peaks are also observed in PcG domains. Surprisingly, in vivo deletion of the four characterized strong PREs from the PcG regulated invected-engrailed (inv-en) gene complex did not disrupt the formation of the H3K27me3 domain and did not affect inv-en expression in embryos or larvae suggesting the presence of redundant PcG recruitment mechanism. Further, the 3D-structure of the inv-en domain was only minimally altered by the deletion of the strong PREs. A reporter construct containing a 7.5kb en fragment that contains three weak peaks but no large PcG peaks forms an H3K27me3 domain and is PcG-regulated. Our data suggests a model for the recruitment of PcG-complexes to Drosophila genes via interactions with multiple, weak PREs spread throughout an H3K27me3 domain. PMID:27466807

  15. A functionally conserved Polycomb response element from mouse HoxD complex responds to heterochromatin factors

    NASA Astrophysics Data System (ADS)

    Vasanthi, Dasari; Nagabhushan, A.; Matharu, Navneet Kaur; Mishra, Rakesh K.

    2013-10-01

    Anterior-posterior body axis in all bilaterians is determined by the Hox gene clusters that are activated in a spatio-temporal order. This expression pattern of Hox genes is established and maintained by regulatory mechanisms that involve higher order chromatin structure and Polycomb group (PcG) and trithorax group (trxG) proteins. We identified earlier a Polycomb response element (PRE) in the mouse HoxD complex that is functionally conserved in flies. We analyzed the molecular and genetic interactions of mouse PRE using Drosophila melanogaster and vertebrate cell culture as the model systems. We demonstrate that the repressive activity of this PRE depends on PcG/trxG genes as well as the heterochromatin components. Our findings indicate that a wide range of factors interact with the HoxD PRE that can contribute to establishing the expression pattern of homeotic genes in the complex early during development and maintain that pattern at subsequent stages.

  16. The trichomonad cysteine proteinase TVCP4 transcript contains an iron-responsive element.

    PubMed

    Solano-González, Eduardo; Burrola-Barraza, Eduviges; León-Sicairos, Claudia; Avila-González, Leticia; Gutiérrez-Escolano, Lorena; Ortega-López, Jaime; Arroyo, Rossana

    2007-06-26

    The differential expression of the Trichomonas vaginalis cysteine proteinase TVCP4 by iron at the protein synthesis level and the prediction of an iron-responsive element (IRE)-like stem-loop structure at the 5'-region of the T. vaginalis cysteine proteinase 4 gene (tvcp4) mRNA suggest a post-transcriptional mechanism of iron regulation in trichomonads mediated by an IRE/IRP-like system. Gel-shifting, UV cross-linking and competition experiments demonstrated that this IRE-like structure specifically bound to human iron regulatory protein-1. IRP-like cytoplasmic proteins that bound human ferritin IRE sequence transcripts at low-iron conditions were also found in trichomonads. Thus, a post-transcriptional regulatory mechanism by iron for tvcp4 mediated by IRE/IRP-like interactions was found. PMID:17553495

  17. Targeted site-specific cleavage of HIV-1 viral Rev responsive element by copper aminoglycosides.

    PubMed

    Sreedhara, A; Cowan, J A

    2001-02-01

    Site-specific cleavage of the HIV-1 viral Rev responsive element by copper aminoglycosides is reported under physiological conditions. This bubble and stem-loop RNA structure is efficiently targeted at micromolar concentrations of complex. The specificity of cleavage of structured viral RNA relative to a non-cognate tRNAPhe of well-defined secondary and tertiary structure is demonstrated. Cleavage products from simpler substrates [diribonucleotide (ApA) and 2',3'-cyclic monophosphate ester (cAMP)] were analyzed by 31P NMR and demonstrate a hydrolytic mechanism in the absence of external redox agents. These results demonstrate copper aminoglycosides to be highly efficient chemical nucleases with a targeting capability for viral RNA and suggest a novel methodology to counter RNA viruses.

  18. The trichomonad cysteine proteinase TVCP4 transcript contains an iron-responsive element.

    PubMed

    Solano-González, Eduardo; Burrola-Barraza, Eduviges; León-Sicairos, Claudia; Avila-González, Leticia; Gutiérrez-Escolano, Lorena; Ortega-López, Jaime; Arroyo, Rossana

    2007-06-26

    The differential expression of the Trichomonas vaginalis cysteine proteinase TVCP4 by iron at the protein synthesis level and the prediction of an iron-responsive element (IRE)-like stem-loop structure at the 5'-region of the T. vaginalis cysteine proteinase 4 gene (tvcp4) mRNA suggest a post-transcriptional mechanism of iron regulation in trichomonads mediated by an IRE/IRP-like system. Gel-shifting, UV cross-linking and competition experiments demonstrated that this IRE-like structure specifically bound to human iron regulatory protein-1. IRP-like cytoplasmic proteins that bound human ferritin IRE sequence transcripts at low-iron conditions were also found in trichomonads. Thus, a post-transcriptional regulatory mechanism by iron for tvcp4 mediated by IRE/IRP-like interactions was found.

  19. Human GLI-2 Is a Tat Activation Response Element-Independent Tat Cofactor

    PubMed Central

    Browning, Catherine M.; Smith, Michael J.; Clark, Nina M.; Lane, Brian R.; Parada, Camilo; Montano, Monty; KewalRamani, Vineet N.; Littman, Dan R.; Essex, Max; Roeder, Robert G.; Markovitz, David M.

    2001-01-01

    Zinc finger-containing GLI proteins are involved in the development of Caenorhabditis elegans, Xenopus, Drosophila, zebrafish, mice, and humans. In this study, we show that an isoform of human GLI-2 strongly synergizes with the Tat transactivating proteins of human immunodeficiency virus types 1 and 2 (HIV-1 and -2) and markedly stimulates viral replication. GLI-2 also synergizes with the previously described Tat cofactor cyclin T1 to stimulate Tat function. Surprisingly, GLI-2/Tat synergy is not dependent on either a typical GLI DNA binding site or an intact Tat activation response element but does require an intact TATA box. Thus, GLI-2/Tat synergy results from a mechanism of action which is novel both for a GLI protein and for a Tat cofactor. These findings link the GLI family of transcriptional and developmental regulatory proteins to Tat function and HIV replication. PMID:11160734

  20. Identification of a glucocorticoid-responsive element in Epstein-Barr virus.

    PubMed Central

    Kupfer, S R; Summers, W C

    1990-01-01

    Immortalization of B lymphocytes by Epstein-Barr virus (EBV) is complex and poorly understood. However, some evidence suggests that glucocorticoids influence this process. We identified a glucocorticoid-responsive element in the BamHI C fragment of EBV which we call ES-1. In glucocorticoid-treated cells, ES-1 enhanced chloramphenicol acetyltransferase gene expression from the herpes simplex virus thymidine kinase promoter, as well as the EBV Bam-C promoter, from which several latent viral gene products are transcribed. By Northern blot analysis, glucocorticoid treatment enhanced transcription from the Bam-C promoter in Jijoye cells, a Burkitt's lymphoma cell line. In addition, the DNA-binding domain of the glucocorticoid receptor bound specifically to the ES-1 region. These glucocorticoid effects on the Bam-C promoter region may provide some insight into the process of EBV immortalization. Images PMID:2157866

  1. Trace element concentrations in surface estuarine and marine sediments along the Mississippi Gulf Coast following Hurricane Katrina.

    PubMed

    Warren, Crystal; Duzgoren-Aydin, Nurdan S; Weston, James; Willett, Kristine L

    2012-01-01

    Hurricanes are relatively frequent ecological disturbances that may cause potentially long-term impacts to the coastal environment. Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, and caused a storm surge with the potential to change the trace element content of coastal surface sediments. In this study, surface estuarine and marine sediments were collected monthly following the storm from ten sites along the Mississippi Gulf Coast (Mobile Bay, Grand Bay Bayous Heron and Cumbest, Pascagoula, Ocean Springs, Biloxi Gulf, Back Biloxi Bay, Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina). Concentrations of V, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb were measured by inductively coupled plasma-mass spectrometry to evaluate their temporal and spatial variations in the year following Hurricane Katrina. Sediments were characterized by pH, particle size distribution and total carbon and nitrogen content. Trace element contents of the sediments were determined in both <2 mm and <63 μm grain size fractions. Results revealed no significant temporal and spatial variability in trace element concentrations, in either size fraction. Potential ecological risk of the sediments was assessed by using NOAA SQuiRTs' guideline values; most concentrations remained below probable adverse effects guidelines to marine organisms suggesting that trace elements redistributed by Hurricane Katrina would not cause an adverse impact on resident organisms. Instead, the concentrations of trace elements were site-dependent, with specific contaminants relating to the use of the area prior to Hurricane Katrina.

  2. Thyroid Hormone Response Element Half-Site Organization and Its Effect on Thyroid Hormone Mediated Transcription

    PubMed Central

    Paquette, Martin A.; Atlas, Ella; Wade, Mike G.; Yauk, Carole L.

    2014-01-01

    Thyroid hormone (TH) exerts its effects by binding to the thyroid hormone receptor (TR), which binds to TH response elements (TREs) to regulate target gene expression. We investigated the relative ability of liganded homodimers TR and retinoid X receptor (RXR), and the heterodimer TR/RXR, to regulate gene expression for the TRE half-site organizations: direct repeat 4 (DR4), inverted repeat 0 (IR0) and everted repeat 6 (ER6). Luciferase reporter assays using a DR4 TRE suggest that both the TR homodimer and TR/RXR heterodimer regulate luciferase expression in the presence of their respective ligands. However, in the presence of the IR0 TRE, transfection with TR/RXR and RXR alone increased luciferase activity and there was no effect of TR alone. The presence of 9-cis-retinoic acid was necessary for luciferase expression, whereas TH treatment alone was insufficient. For the ER6 TRE, transfection with TR/RXR, TR alone and RXR alone (in the presence of their respective ligands) all caused a significant increase in luciferase activity. When both ligands were present, transfection with both TR/RXR caused more activation. Finally, we investigated the efficacy of the TR-antagonist 1–850 in inhibiting transcription by TR or TR/RXR at DR4 and ER6 TREs. We found that 1–850 did not suppress luciferase activation in the presence of TR/RXR for the ER6 TRE, suggesting conformational changes of the ligand binding domain of the TR when bound to different TRE half-site organizations. Collectively, the findings indicate that there are fundamental differences between TRE configurations that affect nuclear receptor interactions with the response element and ability to bind ligands and antagonists. PMID:24971931

  3. The human endogenous retrovirus K Rev response element coincides with a predicted RNA folding region.

    PubMed Central

    Yang, J; Bogerd, H; Le, S Y; Cullen, B R

    2000-01-01

    Human endogenous retrovirus K (HERV-K) is the name given to an approximately 30-million-year-old family of endogenous retroviruses present at >50 copies per haploid human genome. Previously, the HERV-K were shown to encode a nuclear RNA export factor, termed K-Rev, that is the functional equivalent of the H-Rev protein encoded by human immunodeficiency virus type 1. HERV-K was also shown to contain a cis-acting target element, the HERV-K Rev response element (K-RRE), that allowed the nuclear export of linked RNA transcripts in the presence of either K-Rev or H-Rev. Here, we demonstrate that the functionally defined K-RRE coincides with a statistically highly significant unusual RNA folding region and present a potential RNA secondary structure for the approximately 416-nt K-RRE. Both in vitro and in vivo assays of sequence specific RNA binding were used to map two primary binding sites for K-Rev, and one primary binding site for H-Rev, within the K-RRE. Of note, all three binding sites map to discrete predicted RNA stem-loop subdomains within the larger K-RRE structure. Although almost the entire 416-nt K-RRE was required for the activation of nuclear RNA export in cells expressing K-Rev, mutational inactivation of the binding sites for K-Rev resulted in the selective loss of the K-RRE response to K-Rev but not to H-Rev. Together, these data strongly suggest that the K-RRE, like the H-RRE, coincides with an extensive RNA secondary structure and identify specific sites within the K-RRE that can recruit either K-Rev or H-Rev to HERV-K RNA transcripts. PMID:11105755

  4. Neural Network and Response Surface Methodology for Rocket Engine Component Optimization

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, Rajkumar; Papita, Nilay; Shyy, Wei; Tucker, P. Kevin; Griffin, Lisa W.; Haftka, Raphael; Fitz-Coy, Norman; McConnaughey, Helen (Technical Monitor)

    2000-01-01

    The goal of this work is to compare the performance of response surface methodology (RSM) and two types of neural networks (NN) to aid preliminary design of two rocket engine components. A data set of 45 training points and 20 test points obtained from a semi-empirical model based on three design variables is used for a shear coaxial injector element. Data for supersonic turbine design is based on six design variables, 76 training, data and 18 test data obtained from simplified aerodynamic analysis. Several RS and NN are first constructed using the training data. The test data are then employed to select the best RS or NN. Quadratic and cubic response surfaces. radial basis neural network (RBNN) and back-propagation neural network (BPNN) are compared. Two-layered RBNN are generated using two different training algorithms, namely solverbe and solverb. A two layered BPNN is generated with Tan-Sigmoid transfer function. Various issues related to the training of the neural networks are addressed including number of neurons, error goals, spread constants and the accuracy of different models in representing the design space. A search for the optimum design is carried out using a standard gradient-based optimization algorithm over the response surfaces represented by the polynomials and trained neural networks. Usually a cubic polynominal performs better than the quadratic polynomial but exceptions have been noticed. Among the NN choices, the RBNN designed using solverb yields more consistent performance for both engine components considered. The training of RBNN is easier as it requires linear regression. This coupled with the consistency in performance promise the possibility of it being used as an optimization strategy for engineering design problems.

  5. Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

    PubMed

    Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

    2015-10-01

    Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

  6. Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

    PubMed

    Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

    2015-10-01

    Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies. PMID:26313586

  7. Optimization of composite flour biscuits by mixture response surface methodology.

    PubMed

    Okpala, Laura C; Okoli, Eric C

    2013-08-01

    Biscuits were produced from blends of pigeon pea, sorghum and cocoyam flours. The study was carried out using mixture response surface methodology as the optimization technique. Using the simplex centroid design, 10 formulations were obtained. Protein and sensory quality of the biscuits were analyzed. The sensory attributes studied were appearance, taste, texture, crispness and general acceptability, while the protein quality indices were biological value and net protein utilization. The results showed that while the addition of pigeon pea improved the protein quality, its addition resulted in reduced sensory ratings for all the sensory attributes with the exception of appearance. Some of the biscuits had sensory ratings, which were not significantly different (p > 0.05) from biscuits made with wheat. Rat feeding experiments indicated that the biological value and net protein utilization values obtained for most of the biscuits were above minimum recommended values. Optimization suggested biscuits containing 75.30% sorghum, 0% pigeon pea and 24.70% cocoyam flours as the best proportion of these components. This sample received good scores for the sensory attributes.

  8. Polysaccharide extraction from Sphallerocarpus gracilis roots by response surface methodology.

    PubMed

    Ma, Tingting; Sun, Xiangyu; Tian, Chengrui; Luo, Jiyang; Zheng, Cuiping; Zhan, Jicheng

    2016-07-01

    The extraction process of Sphallerocarpus gracilis root polysaccharides (SGRP) was optimized using response surface methodology with two methods [hot-water extraction (HWE) and ultrasonic-assisted extraction (UAE)]. The antioxidant activities of SGRP were determined, and the structural features of the untreated materials (HWE residue and UAE residue) and the extracted polysaccharides were compared by scanning electron microscopy. Results showed that the optimal UAE conditions were extraction temperature of 81°C, extraction time of 1.7h, liquid-solid ratio of 17ml/g, ultrasonic power of 300W and three extraction cycles. The optimal HWE conditions were 93°C extraction temperature, 3.6h extraction time, 21ml/g liquid-solid ratio and three extraction cycles. UAE offered a higher extraction yield with a shorter time, lower temperature and a lower solvent consumption compared with HWE, and the extracted polysaccharides possessed a higher antioxidant capacity. Therefore, UAE could be used as an alternative to conventional HWE for SGRP extraction. PMID:27032488

  9. Ectoine production by Halomonas boliviensis: optimization using response surface methodology.

    PubMed

    Van-Thuoc, Doan; Guzmán, Héctor; Thi-Hang, Mai; Hatti-Kaul, Rajni

    2010-10-01

    Two cultivation steps were used for production of biomass and ectoine by Halomonas boliviensis, respectively. The optimization of some nutrient parameters in each step was investigated by using response surface methodology. Twenty and 12 experiments were performed to attain optimal conditions for biomass and ectoine production, respectively. The model predicted a maximum biomass concentration of 3.34 g/L on optimization of NH(4)Cl, K(2)HPO(4), and MgSO(4)•7H(2)O concentrations during the first cultivation, while a maximum ectoine concentration of 1.27 g/L was predicted on optimizing NaCl and monosodium glutamate concentrations in the second cultivation. The experimental values obtained (3.36 g biomass/L and 1.25 g ectoine/L) were in good agreement with the predicted values. The optimized conditions were also used for two-step 1.5-L fed-batch fermentations. In the first step, biomass concentration of 28.7 g/L was obtained while in the second step biomass concentration increased to 63 g/L. Ectoine concentration of 9.2 g/L was obtained, and the overall ectoine productivity was 6.3 g/L/day, being among the highest reported so far.

  10. Polysaccharide extraction from Abelmoschus esculentus: optimization by response surface methodology.

    PubMed

    Samavati, Vahid

    2013-06-01

    Crude polysaccharide extraction from the Iranian Abelmoschus esculentus was performed using water decoction. Response surface methodology (RSM), based on a five level, four variable central composite rotatable design (CCRD), was employed to obtain the best possible combination of extraction time (X1: 0.5-6.5 h), extraction temperature (X2: 80-100 °C), number of extraction (X3: 1-5), and water to the raw material ratio (X4: 4-28) for maximum polysaccharide extraction. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis and also analyzed by appropriate statistical methods (ANOVA). The optimum extraction conditions were as follows: extraction time of 4.94 h, extraction temperature of 94.97 °C, number of extraction of 4, and the ratio of water to raw material of 21.74. Under these conditions, the experimental yield was 16.895±0.29%, which is well in close agreement with the value predicted by the model 16.916%.

  11. Response surface methodology for cadmium biosorption on Pseudomonas aeruginosa.

    PubMed

    Ahmady-Asbchin, Salman

    2016-01-01

    In this research the effects of various physicochemical factors on Cd(2+) biosorption such as initial metal concentration, pH and contact exposure time were studied. This study has shown a Cd(2+) biosorption, equilibrium time of about 5 min for Pseudomonas aeruginosa and the adsorption equilibrium data were well described by Langmuir equation. The maximum capacity for biosorption has been extrapolated to 0.56 mmol.g(-1) for P. aeruginosa. The thermodynamic properties ΔG(0), ΔH(0), and ΔS(0) of Cd(2+) for biosorption were analyzed by the equilibrium constant value obtained from experimented data at different temperatures. The results show that biosorption of Cd(2+) by P. aeruginosa are endothermic and spontaneous with ΔH value of 36.35 J.mol(-1). By response surface methodology, the quadratic model has adequately described the experimental data based on the adjusted determination coefficient (R(2) = 0.98). The optimum conditions for maximum uptake onto the biosorbent were established at 0.5 g.l(-1) biosorbent concentration, pH 6 for the aqueous solution, and a temperature of 30 °C. PMID:27232396

  12. SEM-EDS-Based Elemental Identification on the Enamel Surface after the Completion of Orthodontic Treatment: In Vitro Studies

    PubMed Central

    Seeliger, Julia; Lipski, Mariusz; Wójcicka, Anna; Gedrange, Tomasz; Woźniak, Krzysztof

    2016-01-01

    Braces as foreign bodies in the mouth carry a risk of side effects and toxicity to the human body. This article presents the results indicating the possible toxic effects of tools used for cleaning the enamel after the completion of orthodontic treatment. The studies were carried out in vitro. The procedure of enamel etching, bonding orthodontic metal brackets, and enamel cleaning after their removal was performed under laboratory conditions. The enamel microstructure and elements present on its surface were evaluated using the scanning electron microscope (SEM). Silicon and aluminium were found in addition to the tooth building elements. PMID:27766265

  13. Characterization of antigen receptor response elements within the interleukin-2 enhancer.

    PubMed Central

    Durand, D B; Shaw, J P; Bush, M R; Replogle, R E; Belagaje, R; Crabtree, G R

    1988-01-01

    T-cell activation and induction of interleukin-2 (IL-2) expression in human T lymphocytes require both interaction of foreign antigen with the T-cell antigen receptor and protein kinase C (PKC) stimulation. Agents such as phorbol 12-myristate 13-acetate (PMA) that stimulate PKC augment the effects of antigen but are not sufficient for IL-2 activation. By analysis of deletion mutants, we identified three DNA sequences extending from -73 to -89, -217 to -255, and -263 to -279, designated IL-2 sites A, D, and E, respectively, that are required for maximal induction of IL-2 expression. One of these regions, site E, interacted with a protein (NF-IL-2E) present only in the nuclei of cells which have been stimulated. The other two sequences interacted with a protein (NF-IL-2A) that is constitutively expressed in T cells. When multiple tandem copies of either the E site or the A site were placed upstream of the gamma-fibrinogen promoter, they activated expression via this promoter in response to signals initiated at the antigen receptor but not following PMA stimulation. For this reason, we denoted them antigen receptor response elements. The uncoupling of antigen receptor and PKC requirements in these studies indicates that these signal pathways are, at least in part, distinct and integrated at the level of the gene. Images PMID:3260003

  14. Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.

    PubMed

    Hafke, Jens B; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J E

    2013-06-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba).

  15. Finite element modeling of human brain response to football helmet impacts.

    PubMed

    Darling, T; Muthuswamy, J; Rajan, S D

    2016-10-01

    The football helmet is used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. While the current helmet design methodology may be adequate for reducing linear acceleration of the head and minimizing TBI, it however has had less effect in minimizing mTBI. The objectives of this study are (a) to develop and validate a coupled finite element (FE) model of a football helmet and the human body, and (b) to assess responses of different regions of the brain to two different impact conditions - frontal oblique and crown impact conditions. The FE helmet model was validated using experimental results of drop tests. Subsequently, the integrated helmet-human body FE model was used to assess the responses of different regions of the brain to impact loads. Strain-rate, strain, and stress measures in the corpus callosum, midbrain, and brain stem were assessed. Results show that maximum strain-rates of 27 and 19 s(-1) are observed in the brain-stem and mid-brain, respectively. This could potentially lead to axonal injuries and neuronal cell death during crown impact conditions. The developed experimental-numerical framework can be used in the study of other helmet-related impact conditions. PMID:26867124

  16. Ethylene-inducible DNA binding proteins that interact with an ethylene-responsive element.

    PubMed Central

    Ohme-Takagi, M; Shinshi, H

    1995-01-01

    We demonstrated that the GCC box, which is an 11-bp sequence (TAAGAGCCGCC) conserved in the 5' upstream region of ethylene-inducible pathogenesis-related protein genes in Nicotiana spp and in some other plants, is the sequence that is essential for ethylene responsiveness when incorporated into a heterologous promoter. Competitive gel retardation assays showed DNA binding activities to be specific to the GCC box sequence in tobacco nuclear extracts. Four different cDNAs encoding DNA binding proteins specific for the GCC box sequence were isolated, and their products were designated ethylene-responsive element binding proteins (EREBPs). The deduced amino acid sequences of EREBPs exhibited no homology with those of known DNA binding proteins or transcription factors; neither did the deduced proteins contain a basic leucine zipper or zinc finger motif. The DNA binding domain was identified within a region of 59 amino acid residues that was common to all four deduced EREBPs. Regions highly homologous to the DNA binding domain of EREBPs were found in proteins deduced from the cDNAs of various plants, suggesting that this domain is evolutionarily conserved in plants. RNA gel blot analysis revealed that accumulation of mRNAs for EREBPs was induced by ethylene, but individual EREBPs exhibited different patterns of expression. PMID:7756828

  17. Finite element modeling of human brain response to football helmet impacts.

    PubMed

    Darling, T; Muthuswamy, J; Rajan, S D

    2016-10-01

    The football helmet is used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. While the current helmet design methodology may be adequate for reducing linear acceleration of the head and minimizing TBI, it however has had less effect in minimizing mTBI. The objectives of this study are (a) to develop and validate a coupled finite element (FE) model of a football helmet and the human body, and (b) to assess responses of different regions of the brain to two different impact conditions - frontal oblique and crown impact conditions. The FE helmet model was validated using experimental results of drop tests. Subsequently, the integrated helmet-human body FE model was used to assess the responses of different regions of the brain to impact loads. Strain-rate, strain, and stress measures in the corpus callosum, midbrain, and brain stem were assessed. Results show that maximum strain-rates of 27 and 19 s(-1) are observed in the brain-stem and mid-brain, respectively. This could potentially lead to axonal injuries and neuronal cell death during crown impact conditions. The developed experimental-numerical framework can be used in the study of other helmet-related impact conditions.

  18. A major thyroid hormone response element in the third intron of the rat growth hormone gene.

    PubMed Central

    Sap, J; de Magistris, L; Stunnenberg, H; Vennström, B

    1990-01-01

    The rat growth hormone (RGH) gene constitutes a well-documented model system for the direct regulation of transcription by thyroid hormones. In order to analyse its interaction with sequences in the RGH gene, we have overproduced the thyroid hormone receptor-alpha (c-erbA) protein using a vaccinia virus expression system. The expressed protein bound T3 and DNA-cellulose with expected affinities, and the major binding site for the receptor protein was found to be located in the third intron of the RGH gene. This site displayed significantly higher affinity for the receptor protein than a previously described thyroid hormone response element (TRE) in the promoter of this gene, and also conferred stronger hormone responsiveness in vivo to a heterologous promoter. The data suggest that this novel TRE plays a major role in the regulation of rat growth hormone gene expression by thyroid hormones. Images Fig. 1. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. PMID:2155782

  19. Characterizing Response to Elemental Unit of Acoustic Imaging Noise: An fMRI Study

    PubMed Central

    Luh, Wen-Ming; Talavage, Thomas M.

    2010-01-01

    Acoustic imaging noise produced during functional magnetic resonance imaging (fMRI) studies can hinder auditory fMRI research analysis by altering the properties of the acquired time-series data. Acoustic imaging noise can be especially confounding when estimating the time course of the hemodynamic response (HDR) in auditory event-related fMRI (fMRI) experiments. This study is motivated by the desire to establish a baseline function that can serve not only as a comparison to other quantities of acoustic imaging noise for determining how detrimental is one's experimental noise, but also as a foundation for a model that compensates for the response to acoustic imaging noise. Therefore, the amplitude and spatial extent of the HDR to the elemental unit of acoustic imaging noise (i.e., a single ping) associated with echoplanar acquisition were characterized and modeled. Results from this fMRI study at 1.5 T indicate that the group-averaged HDR in left and right auditory cortex to acoustic imaging noise (duration of 46 ms) has an estimated peak magnitude of 0.29% (right) to 0.48% (left) signal change from baseline, peaks between 3 and 5 s after stimulus presentation, and returns to baseline and remains within the noise range approximately 8 s after stimulus presentation. PMID:19304477

  20. Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.

    PubMed

    Hafke, Jens B; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J E

    2013-06-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba). PMID:23624858

  1. Involvement of the Sieve Element Cytoskeleton in Electrical Responses to Cold Shocks1[W

    PubMed Central

    Hafke, Jens B.; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J.E.

    2013-01-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca2+-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca2+ influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La3+ in keeping with the involvement of Ca2+ channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca2+ influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba). PMID:23624858

  2. Responses of plant calmodulin to endocytosis induced by rare earth elements.

    PubMed

    Wang, Lihong; Cheng, Mengzhu; Chu, Yunxia; Li, Xiaodong; Chen, David D Y; Huang, Xiaohua; Zhou, Qing

    2016-07-01

    The wide application of rare earth elements (REEs) have led to their diffusion and accumulation in the environment. The activation of endocytosis is the primary response of plant cells to REEs. Calmodulin (CaM), as an important substance in calcium (Ca) signaling systems, regulating almost all of the physiological activities in plants, such as cellular metabolism, cell growth and division. However, the response of CaM to endocytosis activated by REEs remains unknown. By using immunofluorescence labeling and a confocal laser scanning microscope, we found that trivalent lanthanum [La(III)], an REE ion, affected the expression of CaM in endocytosis. Using circular dichroism, X-ray photoelectron spectroscopy and computer simulations, we demonstrated that a low concentration of La(III) could interact with extracellular CaM by electrostatic attraction and was then bound to two Ca-binding sites of CaM, making the molecular structure more compact and orderly, whereas a high concentration of La(III) could be coordinated with cytoplasmic CaM or bound to other Ca-binding sites, making the molecular structure more loose and disorderly. Our results provide a reference for revealing the action mechanisms of REEs in plant cells.

  3. Biomechanical response of the pubic symphysis in lateral pelvic impacts: a finite element study.

    PubMed

    Li, Zuoping; Kim, Jong-Eun; Davidson, James S; Etheridge, Brandon S; Alonso, Jorge E; Eberhardt, Alan W

    2007-01-01

    Automotive side impacts are a leading cause of injuries to the pubic symphysis, yet the mechanisms of those injuries have not been clearly established. Previous mechanical testing of isolated symphyses revealed increased joint laxity following drop tower lateral impacts to isolated pelvic bone structures, which suggested that the joints were damaged by excessive stresses and/or deformations during the impact tests. In the present study, a finite element (FE) model of a female pelvis including a previously validated symphysis sub-model was developed from computed tomography data. The full pelvis model was validated against measured force-time impact responses from drop tower experiments and then used to study the biomechanical response of the symphysis during the experimental impacts. The FE models predicted that the joint underwent a combination of lateral compression, posterior bending, anterior/posterior and superior/inferior shear that exceeded normal physiological levels prior to the onset of bony fractures. Large strains occurred concurrently within the pubic ligaments. Removal of the contralateral constraints to better approximate the boundary conditions of a seated motor vehicle occupant reduced cortical stresses and deformations of the pubic symphysis; however, ligament strains, compressive and shear stresses in the interpubic disc, as well as posterior bending of the joint structure remained as potential sources of joint damage during automotive side impacts. PMID:17399721

  4. Safety assessment of dehydration-responsive element-binding (DREB) 4 protein expressed in E. coli.

    PubMed

    Cao, Bo; He, Xiaoyun; Luo, Yunbo; Ma, Lina; Liu, Pengfei; Cao, Sishuo; Liu, Yaozheng; Zou, Shiying; Xu, Wentao; Huang, Kunlun

    2012-11-01

    Dehydration-responsive element-binding (DREB) proteins are important transcription factors in plant responses and signal transduction. The DREB proteins can improve the drought and salt tolerance of plants, which provides an excellent opportunity to develop stress-tolerant genetically modified crops in the future. In the present study, a novel TaDREB4 gene (GenBank Accession No: AY781355.1) from Triticum aestivum was amplified by PCR (polymerase chain reaction), and the recombinant plasmid pET 30a(+)/TaDREB4 was successfully constructed. The fusion protein was induced by IPTG (isopropyl β-D-1-thiogalactopyranoside) and purified by the HisPrep™ FF 16/10 Column. The purity of the final purified TaDREB4 protein was 93.0%.Bioinformatic analysis and digestive stability tests were conducted to assess the allergenicity of the TaDREB4 protein, and acute toxicity tests were conducted in mice by oral administration of the TaDREB4 protein (5000 mg/kg BW). The results indicated that there was almost no similarity between the TaDREB4 protein and known allergens, and the protein was immediately degraded in simulated gastric and intestinal fluid within 15 s. In addition, no observed adverse effects were found in mice after 14 days. The results preliminary revealed that the protein is safe for human based on the current experiment.

  5. Nonlinear random response of large-scale sparse finite element plate bending problems

    NASA Astrophysics Data System (ADS)

    Chokshi, Swati

    Acoustic fatigue is one of the major design considerations for skin panels exposed to high levels of random pressure at subsonic/supersonic/hypersonic speeds. The nonlinear large deflection random response of the single-bay panels aerospace structures subjected to random excitations at various sound pressure levels (SPLs) is investigated. The nonlinear responses of plate analyses are limited to determine the root-mean-square displacement under uniformly distributed pressure random loads. Efficient computational technologies like sparse storage schemes and parallel computation are proposed and incorporated to solve large-scale, nonlinear large deflection random vibration problems for both types of loading cases: (1) synchronized in time and (2) unsynchronized and statistically uncorrelated in time. For the first time, large scale plate bending problems subjected to unsynchronized load are solved using parallel computing capabilities to account for computational burden due to the simulation of the unsynchronized random pressure fluctuations. The main focus of the research work is placed upon computational issues involved in the nonlinear modal methodologies. A nonlinear FEM method in time domain is incorporated with the Monte Carlo simulation and sparse computational technologies, including the efficient sparse Subspace Eigen-solutions are presented and applied to accurately determine the random response with a refined, large finite element mesh for the first time. Sparse equation solver and sparse matrix operations embedded inside the subspace Eigen-solution algorithms are also exploited. The approach uses the von-Karman nonlinear strain-displacement relations and the classical plate theory. In the proposed methodologies, the solution for a small number (say less than 100) of lowest linear, sparse Eigen-pairs need to be solved for only once, in order to transform nonlinear large displacements from the conventional structural degree-of-freedom (dof) into the modal

  6. Spacing between GT-1 binding sites within a light-responsive element is critical for transcriptional activity.

    PubMed Central

    Gilmartin, P M; Chua, N H

    1990-01-01

    Dissection of the light-responsive element (LRE) located between -166 and -50 of rbcS-3A from pea has revealed critical spacing requirements between the two GT-1 binding sites for light-responsive transcription. An increase in spacing between the two sites by as little as 2 bp reduces dramatically the rbcS-3A transcript levels in vivo. Mutation of the 10 bp between the binding sites leads to slightly lower transcript levels, as do deletions of either 3 bp or 8 bp. Deletions of 5 bp or 7 bp from between the GT-1 binding sites do not affect rbcS-3A transcript levels; however, a deletion of 10 bp virtually abolishes the activity of this element. These spacing changes within the light-responsive element similarly affect transcription of a divergently oriented and truncated nopaline synthase promoter. Most spacing changes between the two GT-1 binding sites, however, do not impair the binding of GT-1 to this element in vitro. Together with previous observations, these results suggest that the nuclear factor GT-1 may interact with the binding sites in either a productive or nonproductive manner and that GT-1 binding is necessary but not sufficient for light-responsive transcription. We also discuss our results in relation to the observed spacing of similar sequence elements present within other light-responsive promoters. PMID:2152170

  7. Enhanced osteoblast response to electrical discharge machining surface.

    PubMed

    Otsuka, Fukunaga; Kataoka, Yu; Miyazaki, Takashi

    2012-01-01

    The purpose of this study is to investigate the surface characteristics and biocompatibility of titanium (Ti) surfaces modified by wire electrical discharge machining (EDM). EDM surface characteristics were evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thin-film X-ray diffractometry (XRD) and contact angle measurements. MC3T3-E1 cell morphology, attachment and proliferation, as well as analysis of osteoblastic gene expressions, on machined surfaces and EDM surfaces were also evaluated. EDM surfaces exhibited high super hydrophilicity, due to high surface energy. XPS and XRD revealed that a passive oxide layer with certain developing thickness onto. EDM surfaces promoted cell attachment, but restrained proliferation. Counted cell numbers increased significantly on the machined surfaces as compared to the EDM surfaces. Real-time PCR analyses showed significantly higher relative mRNA expression levels of osteoblastic genes (ALP, osteocalcin, Runx2, Osterix) in cells cultured on the EDM surfaces as compared to cells cultured on the machined surfaces.

  8. Enhanced osteoblast response to electrical discharge machining surface.

    PubMed

    Otsuka, Fukunaga; Kataoka, Yu; Miyazaki, Takashi

    2012-01-01

    The purpose of this study is to investigate the surface characteristics and biocompatibility of titanium (Ti) surfaces modified by wire electrical discharge machining (EDM). EDM surface characteristics were evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thin-film X-ray diffractometry (XRD) and contact angle measurements. MC3T3-E1 cell morphology, attachment and proliferation, as well as analysis of osteoblastic gene expressions, on machined surfaces and EDM surfaces were also evaluated. EDM surfaces exhibited high super hydrophilicity, due to high surface energy. XPS and XRD revealed that a passive oxide layer with certain developing thickness onto. EDM surfaces promoted cell attachment, but restrained proliferation. Counted cell numbers increased significantly on the machined surfaces as compared to the EDM surfaces. Real-time PCR analyses showed significantly higher relative mRNA expression levels of osteoblastic genes (ALP, osteocalcin, Runx2, Osterix) in cells cultured on the EDM surfaces as compared to cells cultured on the machined surfaces. PMID:22447066

  9. Estrogen contributes to regulating iron metabolism through governing ferroportin signaling via an estrogen response element.

    PubMed

    Qian, Yi; Yin, Chunyang; Chen, Yue; Zhang, Shuping; Jiang, Li; Wang, Fudi; Zhao, Meirong; Liu, Sijin

    2015-05-01

    Ferroportin (FPN) is the only known iron exporter in mammalian cells, and is universally expressed in most types of cells. FPN signaling plays a crucial role in maintaining iron homeostasis through governing the level of intracellular iron. Serum iron storage is conversely related with the estrogen level in the female bodies, and women in post-menopause are possibly subjected to iron retention. However, the potential effects of estrogen on iron metabolism are not clearly understood. Here, FPN mRNA transcription in all selected estrogen receptor positive (ER+) cells was significantly reduced upon 17β-estradiol (E2) treatment; and this inhibitory effect could be attenuated by ER antagonist tamoxifen. Likewise, in murine bone marrow-derived macrophages (BMDMs), FPN reduction with elevated intracellular iron (reflected by increased ferritin) was observed in response to E2; however, ferritin level barely responded to E2 in FPN-null BMDMs. The observation of inhibition of FPN mRNA expression was not replicated in ER(-) cells upon E2. A functional estrogen response element (ERE) was identified within the promoter of FPN, and this ERE was responsible for the suppressive effect of E2 on FPN expression. Moreover, ovariectomized (OVX) and sham-operated (SHAM) mice were used to further confirm the in vitro finding. The expression of hepatic FPN was induced in OVX mice, compared to that in the SHAM mice. Taken together, our results demonstrated that estrogen is involved in regulating FPN expression through a functional ERE on its promoter, providing additional insights into a vital role of estrogen in iron metabolism.

  10. The human beta fibrinogen promoter contains a hepatocyte nuclear factor 1-dependent interleukin-6-responsive element.

    PubMed Central

    Dalmon, J; Laurent, M; Courtois, G

    1993-01-01

    Acute-phase reactants are liver proteins whose synthesis is positively or negatively regulated during inflammation. The main mediators of this phenomenon are glucocorticoids and interleukin-6 (IL-6), a pleiotropic cytokine that also controls hematopoiesis. Functional analysis of several acute-phase reactant promoter regions has identified two major DNA motifs used by IL-6-regulated genes. The first one corresponds to a CTGG(G/A)AA sequence, and the other is a binding site for members of the C/EBP family of nuclear proteins. We have previously shown that the human beta fibrinogen (beta Fg) promoter contains an IL-6-responsive region, located between bp -150 and -67 (P. Huber, M. Laurent, and J. Dalmon, J. Biol. Chem. 265:5695-5701, 1990). In this study, using DNase I footprinting, mobility shift assays, and mutagenesis, we demonstrate that at least three subdomains of this region are necessary to observe a full response to IL-6. The most distal contains a CTGGGAA motif, and its mutation inhibits IL-6 stimulation. Another, which is able to interact with several distinct nuclear proteins, among them members of the C/EBP family, is dispensable for IL-6 induction but plays an important role in the constitutive expression of beta Fg. Finally, a proximal hepatocyte nuclear factor 1 binding site, already described as the major determinant of beta Fg tissue-specific expression, is also required for IL-6 stimulation. These results indicate a complex interplay between nuclear proteins within the beta Fg IL-6-responsive region and suggest a tight functional coupling between the tissue-specific and inducible elements. Images PMID:8423785

  11. Prebending the estrogen response element destabilizes binding of the estrogen receptor DNA binding domain.

    PubMed Central

    Kim, J; de Haan, G; Nardulli, A M; Shapiro, D J

    1997-01-01

    Binding of many eukaryotic transcription regulatory proteins to their DNA recognition sequences results in conformational changes in DNA. To test the effect of altering DNA topology by prebending a transcription factor binding site, we examined the interaction of the estrogen receptor (ER) DNA binding domain (DBD) with prebent estrogen response elements (EREs). When the ERE in minicircle DNA was prebent toward the major groove, which is in the same direction as the ER-induced DNA bend, there was no significant effect on ER DBD binding relative to the linear counterparts. However, when the ERE was bent toward the minor groove, in a direction that opposes the ER-induced DNA bend, there was a four- to eightfold reduction in ER DBD binding. Since reduced binding was also observed with the ERE in nicked circles, the reduction in binding was not due to torsional force induced by binding of ER DBD to the prebent ERE in covalently closed minicircles. To determine the mechanism responsible for reduced binding to the prebent ERE, we examined the effect of prebending the ERE on the association and dissociation of the ER DBD. Binding of the ER DBD to ERE-containing minicircles was rapid when the EREs were prebent toward either the major or minor groove of the DNA (k(on) of 9.9 x 10(6) to 1.7 x 10(7) M(-1) s(-1)). Prebending the ERE toward the minor groove resulted in an increase in k(off) of four- to fivefold. Increased dissociation of the ER DBD from the ERE is, therefore, the major factor responsible for reduced binding of the ER DBD to an ERE prebent toward the minor groove. These data provide the first direct demonstration that the interaction of a eukaryotic transcription factor with its recognition sequence can be strongly influenced by altering DNA topology through prebending the DNA. PMID:9154816

  12. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  13. The magnetic field and the evolution of element spots on the surface of the HgMn eclipsing binary ARAur

    NASA Astrophysics Data System (ADS)

    Hubrig, S.; Savanov, I.; Ilyin, I.; González, J. F.; Korhonen, H.; Lehmann, H.; Schöller, M.; Granzer, T.; Weber, M.; Strassmeier, K. G.; Hartmann, M.; Tkachenko, A.

    2010-10-01

    The system ARAur is a young late B-type double-lined eclipsing binary with a primary star of HgMn peculiarity. We applied the Doppler imaging method to reconstruct the distribution of Fe and Y over the surface of the primary using spectroscopic time series obtained in 2005 and from 2008 October to 2009 February. The results show a remarkable evolution of the element distribution and overabundances. Measurements of the magnetic field with the moment technique using several elements reveal the presence of a longitudinal magnetic field of the order of a few hundred gauss in both stellar components and a quadratic field of the order of 8kG on the surface of the primary star. Based on observations obtained at the 2.56-m Nordic Optical Telescope on La Palma, the Karl-Schwarzschild-Observatorium in Tautenburg and the STELLA robotic telescope on Tenerife. E-mail: shubrig@aip.de

  14. Characterization of transceive surface element designs for 7 tesla magnetic resonance imaging of the prostate: radiative antenna and microstrip

    NASA Astrophysics Data System (ADS)

    Ipek, Ö.; Raaijmakers, A. J. E.; Klomp, D. W. J.; Lagendijk, J. J. W.; Luijten, P. R.; van den Berg, C. A. T.

    2012-01-01

    Ultra-high field magnetic resonance (⩾7 tesla) imaging (MRI) faces challenges with respect to efficient spin excitation and signal reception from deeply situated organs. Traditional radio frequency surface coil designs relying on near-field coupling are suboptimal at high field strengths. Better signal penetration can be obtained by designing a radiative antenna in which the energy flux is directed to the target location. In this paper, two different radiative antenna designs are investigated to be used as transceive elements, which employ different dielectric permittivities for the antenna substrate. Their transmit and receive performances in terms of B+1, local SAR (specific absorption rate) and SNR (signal-to-noise ratio) were compared using extensive electromagnetic simulations and MRI measurements with traditional surface microstrip coils. Both simulations and measurements demonstrated that the radiative element shows twofold gain in B+1 and SNR at 10 cm depth, and additionally a comparable SAR peak value. In terms of transmit performance, the radiative antenna with a dielectric permittivity of 37 showed a 24% more favorable local SAR10g avg/(B+1)2 ratio than the radiative antenna with a dielectric permittivity of 90. In receive, the radiative element with a dielectric permittivity of 90 resulted in a 20% higher SNR for shallow depths, but for larger depths this difference diminished compared to the radiative element with a dielectric permittivity of 37. Therefore, to image deep anatomical regions effectively, the radiative antenna with a dielectric permittivity of 37 is favorable.

  15. Characterization of transceive surface element designs for 7 tesla magnetic resonance imaging of the prostate: radiative antenna and microstrip.

    PubMed

    Ipek, O; Raaijmakers, A J E; Klomp, D W J; Lagendijk, J J W; Luijten, P R; van den Berg, C A T

    2012-01-21

    Ultra-high field magnetic resonance (≥7 tesla) imaging (MRI) faces challenges with respect to efficient spin excitation and signal reception from deeply situated organs. Traditional radio frequency surface coil designs relying on near-field coupling are suboptimal at high field strengths. Better signal penetration can be obtained by designing a radiative antenna in which the energy flux is directed to the target location. In this paper, two different radiative antenna designs are investigated to be used as transceive elements, which employ different dielectric permittivities for the antenna substrate. Their transmit and receive performances in terms of B(+)(1), local SAR (specific absorption rate) and SNR (signal-to-noise ratio) were compared using extensive electromagnetic simulations and MRI measurements with traditional surface microstrip coils. Both simulations and measurements demonstrated that the radiative element shows twofold gain in B(+)(1) and SNR at 10 cm depth, and additionally a comparable SAR peak value. In terms of transmit performance, the radiative antenna with a dielectric permittivity of 37 showed a 24% more favorable local SAR(10g avg)/(B(+)(1))(2) ratio than the radiative antenna with a dielectric permittivity of 90. In receive, the radiative element with a dielectric permittivity of 90 resulted in a 20% higher SNR for shallow depths, but for larger depths this difference diminished compared to the radiative element with a dielectric permittivity of 37. Therefore, to image deep anatomical regions effectively, the radiative antenna with a dielectric permittivity of 37 is favorable. PMID:22170777

  16. Analysis of surface cracks at hole by a 3-D weight function method with stresses from finite element method

    NASA Technical Reports Server (NTRS)

    Zhao, W.; Newman, J. C., Jr.; Sutton, M. A.; Shivakumar, K. N.; Wu, X. R.

    1995-01-01

    Parallel with the work in Part-1, stress intensity factors for semi-elliptical surface cracks emanating from a circular hole are determined. The 3-D weight function method with the 3D finite element solutions for the uncracked stress distribution as in Part-1 is used for the analysis. Two different loading conditions, i.e. remote tension and wedge loading, are considered for a wide range in geometrical parameters. Both single and double surface cracks are studied and compared with other solutions available in the literature. Typical crack opening displacements are also provided.

  17. Identification of a peroxisome proliferator responsive element (PPRE)-like cis-element in mouse plasminogen activator inhibitor-1 gene promoter

    SciTech Connect

    Chen Jiegen; Li Xi; Huang Haiyan; Liu Honglei; Liu Deguo; Song Tanjing; Ma Chungu; Ma Duan; Song Houyan; Tang Qiqun . E-mail: qqtang@shmu.edu.cn

    2006-09-01

    PAI-1 is expressed and secreted by adipose tissue which may mediate the pathogenesis of obesity-associated cardiovascular complications. Evidence is presented in this report that PAI-1 is not expressed by preadipocyte, but significantly induced during 3T3-L1 adipocyte differentiation and the PAI-1 expression correlates with the induction of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}). A peroxisome proliferator responsive element (PPRE)-like cis-element (-206TCCCCCATGCCCT-194) is identified in the mouse PAI-1 gene promoter by electrophoretic mobility shift assay (EMSA) combined with transient transfection experiments; the PPRE-like cis-element forms a specific DNA-protein complex only with adipocyte nuclear extracts, not with preadipocyte nuclear extracts; the DNA-protein complex can be totally competed away by non-labeled consensus PPRE, and can be supershifted with PPAR{gamma} antibody. Mutation of this PPRE-like cis-element can abolish the transactivation of mouse PAI-1 promoter mediated by PPAR{gamma}. Specific PPAR{gamma} ligand Pioglitazone can significantly induce the PAI-1 expression, and stimulate the secretion of PAI-1 into medium.

  18. UNDERSTANDING SYSTEMATIC MEASUREMENT ERROR IN THERMAL-OPTICAL ANALYSIS FOR PM BLACK CARBON USING RESPONSE SURFACES AND SURFACE CONFIDENCE INTERVALS

    EPA Science Inventory

    Results from a NIST-EPA Interagency Agreement on Understanding Systematic Measurement Error in Thermal-Optical Analysis for PM Black Carbon Using Response Surfaces and Surface Confidence Intervals will be presented at the American Association for Aerosol Research (AAAR) 24th Annu...

  19. Isoniazid suppresses antioxidant response element activities and impairs adipogenesis in mouse and human preadipocytes

    SciTech Connect

    Chen, Yanyan; Xue, Peng; Hou, Yongyong; Zhang, Hao; Zheng, Hongzhi; Zhou, Tong; Qu, Weidong; Teng, Weiping; Zhang, Qiang; Andersen, Melvin E.; Pi, Jingbo

    2013-12-15

    Transcriptional signaling through the antioxidant response element (ARE), orchestrated by the Nuclear factor E2-related factor 2 (Nrf2), is a major cellular defense mechanism against oxidative or electrophilic stress. Here, we reported that isoniazid (INH), a widely used antitubercular drug, displays a substantial inhibitory property against ARE activities in diverse mouse and human cells. In 3T3-L1 preadipocytes, INH concentration-dependently suppressed the ARE-luciferase reporter activity and mRNA expression of various ARE-dependent antioxidant genes under basal and oxidative stressed conditions. In keeping with our previous findings that Nrf2-ARE plays a critical role in adipogenesis by regulating expression of CCAAT/enhancer-binding protein β (C/EBPβ) and peroxisome proliferator-activated receptor γ (PPARγ), suppression of ARE signaling by INH hampered adipogenic differentiation of 3T3-L1 cells and human adipose-derived stem cells (ADSCs). Following adipogenesis induced by hormonal cocktails, INH-treated 3T3-L1 cells and ADSCs displayed significantly reduced levels of lipid accumulation and attenuated expression of C/EBPα and PPARγ. Time-course studies in 3T3-L1 cells revealed that inhibition of adipogenesis by INH occurred in the early stage of terminal adipogenic differentiation, where reduced expression of C/EBPβ and C/EBPδ was observed. To our knowledge, the present study is the first to demonstrate that INH suppresses ARE signaling and interrupts with the transcriptional network of adipogenesis, leading to impaired adipogenic differentiation. The inhibition of ARE signaling may be a potential underlying mechanism by which INH attenuates cellular antioxidant response contributing to various complications. - Highlights: • Isoniazid suppresses ARE-mediated transcriptional activity. • Isoniazid inhibits adipogenesis in preadipocytes. • Isoniazid suppresses adipogenic gene expression during adipogenesis.

  20. Identification of Aspergillus Brla Response Elements (Bres) by Genetic Selection in Yeast

    PubMed Central

    Chang, Y. C.; Timberlake, W. E.

    1993-01-01

    The brlA gene of Aspergillus nidulans plays a central role in controlling conidiophore development. To test the hypothesis that brlA encodes a transcriptional regulator and to identify sites of interaction for the BrlA polypeptide, we expressed brlA in Saccharomyces cerevisiae (yeast) strains containing Aspergillus DNA sequences inserted upstream of a minimal yeast promoter fused to the Escherichia coli lacZ gene. Initially, a DNA fragment from the promoter region of the developmentally regulated rodA gene was tested and shown to mediate brlA-dependent transcriptional activation. Two additional DNA fragments were selected from an Aspergillus genomic library by their ability to respond to brlA in yeast. These fragments contained multiple copies of a sequence motif present in the rodA fragment, which we propose to be sites for BrlA interaction and designate brlA response elements (BREs). DNA fragments containing BREs upstream of a minimal Aspergillus promoter were capable of conferring developmental regulation in Aspergillus. Deletion of BREs from the upstream region of rodA greatly decreased its developmental induction. Multiple copies of a synthetic oligonucleotide with the consensus sequence identified among the BREs mediated brlA-dependent transcriptional activation in yeast. The results show that a primary activity of brlA is transcriptional activation and tentatively identify sites of interaction for the BrlA polypeptide. PMID:8417986

  1. Finite element prediction of seismic response modification of monumental structures utilizing base isolation

    NASA Astrophysics Data System (ADS)

    Spanos, Konstantinos; Anifantis, Nikolaos; Kakavas, Panayiotis

    2015-05-01

    The analysis of the mechanical behavior of ancient structures is an essential engineering task concerning the preservation of architectural heritage. As many monuments of classical antiquity are located in regions of earthquake activity, the safety assessment of these structures, as well as the selection of possible restoration interventions, requires numerical models capable of correctly representing their seismic response. The work presented herein was part of a research project in which a better understanding of the dynamics of classical column-architrave structures was sought by means of numerical techniques. In this paper, the seismic behavior of ancient monumental structures with multi-drum classical columns is investigated. In particular, the column-architrave classical structure under strong ground excitations was represented by a finite element method. This approach simulates the individual rock blocks as distinct rigid blocks interconnected with slidelines and incorporates seismic isolation dampers under the basement of the structure. Sliding and rocking motions of individual stone blocks and drums are modeled utilizing non-linear frictional contact conditions. The seismic isolation is modeled through the application of pad bearings under the basement of the structure. These pads are interpreted by appropriate rubber and steel layers. Time domain analyses were performed, considering the geometric and material non-linear behavior at the joints and the characteristics of pad bearings. The deformation and failure modes of drum columns subject to seismic excitations of various types and intensities were analyzed. The adverse influence of drum imperfections on structural safety was also examined.

  2. VIP1 response elements mediate mitogen-activated protein kinase 3-induced stress gene expression.

    PubMed

    Pitzschke, Andrea; Djamei, Armin; Teige, Markus; Hirt, Heribert

    2009-10-27

    The plant pathogen Agrobacterium tumefaciens transforms plant cells by delivering its T-DNA into the plant cell nucleus where it integrates into the plant genome and causes tumor formation. A key role of VirE2-interacting protein 1 (VIP1) in the nuclear import of T-DNA during Agrobacterium-mediated plant transformation has been unravelled and VIP1 was shown to undergo nuclear localization upon phosphorylation by the mitogen-activated protein kinase MPK3. Here, we provide evidence that VIP1 encodes a functional bZIP transcription factor that stimulates stress-dependent gene expression by binding to VIP1 response elements (VREs), a DNA hexamer motif. VREs are overrepresented in promoters responding to activation of the MPK3 pathway such as Trxh8 and MYB44. Accordingly, plants overexpressing VIP1 accumulate high levels of Trxh8 and MYB44 transcripts, whereas stress-induced expression of these genes is impaired in mpk3 mutants. Trxh8 and MYB44 promoters are activated by VIP1 in a VRE-dependent manner. VIP1 strongly enhances expression from a synthetic promoter harboring multiple VRE copies and directly interacts with VREs in vitro and in vivo. Chromatin immunoprecipitation assays of the MYB44 promoter confirm that VIP1 binding to VREs is enhanced under conditions of MPK3 pathway stimulation. These results provide molecular insight into the cellular mechanism of target gene regulation by the MPK3 pathway. PMID:19820165

  3. Analysis of trace elements responsible for antioxidant protection by SRXFA method

    NASA Astrophysics Data System (ADS)

    Gonchar, A.; Kolmogorov, Yu; Dikalova, A.; Yelinova, V.; Kondratev, V.

    2001-09-01

    The possibilities of using the energy dispersion synchrotron radiation X-ray fluorescence analysis (SRXFA) for control of blood plasma and liver trace element (TE) content in rats with hyperproduction of oxygen radicals and hair TE content in women with mammary hyperplasia and cancer are demonstrated. Our data show that activity of antioxidant enzymes superoxide dismutase (SOD) and catalase in the blood and liver depends on the amount of TE incorporated into the structure of the active center of these enzymes, which are responsible for antioxidant protection. A decrease of activity of these enzymes is accompanied by an increase of production of free OH radicals in the tissues. Clinical data demonstrated that scalp hair of patients with oncological mammary pathology was characterized by a significant decrease of concentrations of selenium (Se) and zinc (Zn) and by an increase of chromium (Cr). The Se deficit was more pronounced in patients with cancer than in those with mammary hyperplasia ( p<0.05). The SRXFA method permits one to carry out a controllable correction of TE imbalance in many diseases whose development is caused by oxygen radical injury.

  4. cAMP-response-element-binding protein positively regulates breast cancer metastasis and subsequent bone destruction

    SciTech Connect

    Son, Jieun; Lee, Jong-Ho; Kim, Ha-Neui; Ha, Hyunil Lee, Zang Hee

    2010-07-23

    Research highlights: {yields} CREB is highly expressed in advanced breast cancer cells. {yields} Tumor-related factors such as TGF-{beta} further elevate CREB expression. {yields} CREB upregulation stimulates metastatic potential of breast cancer cells. {yields} CREB signaling is required for breast cancer-induced bone destruction. -- Abstract: cAMP-response-element-binding protein (CREB) signaling has been reported to be associated with cancer development and poor clinical outcome in various types of cancer. However, it remains to be elucidated whether CREB is involved in breast cancer development and osteotropism. Here, we found that metastatic MDA-MB-231 breast cancer cells exhibited higher CREB expression than did non-metastatic MCF-7 cells and that CREB expression was further increased by several soluble factors linked to cancer progression, such as IL-1, IGF-1, and TGF-{beta}. Using wild-type CREB and a dominant-negative form (K-CREB), we found that CREB signaling positively regulated the proliferation, migration, and invasion of MDA-MB-231 cells. In addition, K-CREB prevented MDA-MB-231 cell-induced osteolytic lesions in a mouse model of cancer metastasis. Furthermore, CREB signaling in cancer cells regulated the gene expression of PTHrP, MMPs, and OPG, which are closely involved in cancer metastasis and bone destruction. These results indicate that breast cancer cells acquire CREB overexpression during their development and that this CREB upregulation plays an important role in multiple steps of breast cancer bone metastasis.

  5. DSPP contains an IRES element responsible for the translation of dentin phosphophoryn.

    PubMed

    Zhang, Y; Song, Y; Ravindran, S; Gao, Q; Huang, C C; Ramachandran, A; Kulkarni, A; George, A

    2014-02-01

    The major phosphoprotein in dentin is the aspartic acid and serine-rich protein called dentin phosphophoryn (DPP). DPP appears to be synthesized as a part of a larger compound protein, dentin sialophosphoprotein (DSPP). DSPP has never been isolated or detected in dentin extracts. It is now evident that DSPP is a chimeric protein composed of 3 parts: dentin sialoprotein (DSP), DPP, and dentin glycoprotein (DGP). Previous reports have suggested that the BMP1 protease is responsible for processing DSPP. However, unequal amounts of these products are present in the dentin matrix. Here, we provide evidence for an internal ribosome entry site in the DSPP gene that directs the synthesis of DPP. This mechanism would account for unequal amounts of intracellular DSP and DPP. The internal ribosomal entry site (IRES) activity varied in different cell types, suggesting the presence of additional regulatory elements during the translational regulation of DPP. Further, we provide evidence that DPP is transported to the extracellular matrix (ECM) through exosomes. Using tissue recombination and lentivirus-mediated gain-of-function approaches, we also demonstrate that DPP is essential for the formation of well-defined tooth structures with mineralized dentin matrix.

  6. Domain- and nucleotide-specific Rev response element regulation of feline immunodeficiency virus production

    PubMed Central

    Na, Hong; Huisman, Willem; Ellestad, Kristofor K.; Phillips, Tom R.; Power, Christopher

    2010-01-01

    Computational analysis of feline immunodeficiency virus (FIV) RNA sequences indicated that common FIV strains contain a rev response element (RRE) defined by a long unbranched hairpin with 6 stem-loop sub-domains, termed stem-loop A (SLA). To examine the role of the RNA secondary structure of the RRE, mutational analyses were performed in both an infectious FIV molecular clone and a FIV CAT-RRE reporter system. These studies disclosed that the stems within SLA (SA1, 2, 3, 4, and 5) of the RRE were critical but SA6 was not essential for FIV replication and CAT expression. These studies also revealed that the secondary structure rather than an antisense protein (ASP) mediates virus expression and replication in vitro. In addition, a single synonymous mutation within the FIV-RRE, SA3/45, reduced viral reverse transcriptase activity and p24 expression after transfection but in addition also showed a marked reduction in viral expression and production following infection. PMID:20570310

  7. Translational regulation of mammalian and Drosophila citric acid cycle enzymes via iron-responsive elements.

    PubMed Central

    Gray, N K; Pantopoulos, K; Dandekar, T; Ackrell, B A; Hentze, M W

    1996-01-01

    The posttranscriptional control of iron uptake, storage, and utilization by iron-responsive elements (IREs) and iron regulatory proteins (IRPs) provides a molecular framework for the regulation of iron homeostasis in many animals. We have identified and characterized IREs in the mRNAs for two different mitochondrial citric acid cycle enzymes. Drosophila melanogaster IRP binds to an IRE in the 5' untranslated region of the mRNA encoding the iron-sulfur protein (Ip) subunit of succinate dehydrogenase (SDH). This interaction is developmentally regulated during Drosophila embryogenesis. In a cell-free translation system, recombinant IRP-1 imposes highly specific translational repression on a reporter mRNA bearing the SDH IRE, and the translation of SDH-Ip mRNA is iron regulated in D. melanogaster Schneider cells. In mammals, an IRE was identified in the 5' untranslated regions of mitochondrial aconitase mRNAs from two species. Recombinant IRP-1 represses aconitase synthesis with similar efficiency as ferritin IRE-controlled translation. The interaction between mammalian IRPs and the aconitase IRE is regulated by iron, nitric oxide, and oxidative stress (H2O2), indicating that these three signals can control the expression of mitochondrial aconitase mRNA. Our results identify a regulatory link between energy and iron metabolism in vertebrates and invertebrates, and suggest biological functions for the IRE/IRP regulatory system in addition to the maintenance of iron homeostasis. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8643505

  8. An Evolutionary Conserved Epigenetic Mark of Polycomb Response Elements Implemented by Trx/MLL/COMPASS.

    PubMed

    Rickels, Ryan; Hu, Deqing; Collings, Clayton K; Woodfin, Ashley R; Piunti, Andrea; Mohan, Man; Herz, Hans-Martin; Kvon, Evgeny; Shilatifard, Ali

    2016-07-21

    Polycomb response elements (PREs) are specific DNA sequences that stably maintain the developmental pattern of gene expression. Drosophila PREs are well characterized, whereas the existence of PREs in mammals remains debated. Accumulating evidence supports a model in which CpG islands recruit Polycomb group (PcG) complexes; however, which subset of CGIs is selected to serve as PREs is unclear. Trithorax (Trx) positively regulates gene expression in Drosophila and co-occupies PREs to antagonize Polycomb-dependent silencing. Here we demonstrate that Trx-dependent H3K4 dimethylation (H3K4me2) marks Drosophila PREs and maintains the developmental expression pattern of nearby genes. Similarly, the mammalian Trx homolog, MLL1, deposits H3K4me2 at CpG-dense regions that could serve as PREs. In the absence of MLL1 and H3K4me2, H3K27me3 levels, a mark of Polycomb repressive complex 2 (PRC2), increase at these loci. By inhibiting PRC2-dependent H3K27me3 in the absence of MLL1, we can rescue expression of these loci, demonstrating a functional balance between MLL1 and PRC2 activities at these sites. Thus, our study provides rules for identifying cell-type-specific functional mammalian PREs within the human genome. PMID:27447986

  9. Changes in transcriptional pausing modify the folding dynamics of the pH-responsive RNA element

    PubMed Central

    Nechooshtan, Gal; Elgrably-Weiss, Maya; Altuvia, Shoshy

    2014-01-01

    Previously, we described a novel pH-responsive RNA element in Escherichia coli that resides in the 5′ untranslated region of the alx gene and controls its translation in a pH-dependent manner. Under normal growth conditions, this RNA region forms a translationally inactive structure, but when transcribed under alkaline conditions, it forms an active structure producing the Alx protein. We identified two distinct transcriptional pause sites and proposed that pausing at these sites interfered with the formation of the inactive structure while facilitating folding of the active one. Alkali increases the longevity of pausing at these sites, thereby promoting folding of the translationally active form of alx RNA. We show here that mutations that modify the extent and/or position of pausing, although silent with regard to structure stability per se, greatly influence the dynamics of folding and thereby translation. Our data illustrate the mechanistic design of alx regulation, relying on precise temporal and spatial characteristics. We propose that this unique design provides an opportunity for environmental signals such as pH to introduce structural changes in the RNA and thereby modulate expression. PMID:24078087

  10. Activation of interferon-stimulated response element in huh-7 cells replicating hepatitis C virus subgenomic RNA.

    PubMed

    Pai, Mirabel; Prabhu, Ramesh; Panebra, Alfredo; Nangle, Sarah; Haque, Salima; Bastian, Frank; Garry, Robert; Agrawal, Krishna; Goodbourn, Steve; Dash, Srikanta

    2005-01-01

    Interferon-alpha (IFN(alpha)) binds to receptors on the cell surface, which initiate a cascade of signal transduction pathways that leads to transcription of selected genes. This transduction pathway involves binding of transcription factors to a common cis-acting DNA sequence called IFN-stimulated response element (ISRE). To test whether these signaling pathways are functional in hepatitis C virus (HCV)-replicating cells, we studied the regulation of ISRE-mediated transcription of firefly luciferase gene in stable replicon cell lines. A plasmid construct was prepared (pISRELuc) which contains four tandem repeats of 9-27 ISRE sequences positioned directly upstream of the herpes virus 1 thymidine kinase promoter TATA box that drives the expression of firefly luciferase. Regulation of ISRE-mediated expression of firefly luciferase by IFN(alpha) was studied by transfecting this clone into Huh-7 cells replicating HCV subgenomic HCV RNA. The significance of ISRE-mediated transcriptional activation was studied in a replicon cell line by pretreatment of cells with actinomycin D, which inhibits cellular DNA-dependent RNA transcription. IFN treatment activates ISRE-mediated expression of luciferase, indicating that this pathway is functional in Huh-7 cells. Activation of ISRE-mediated transcription of luciferase is relatively high in two Huh-7 stable cell lines replicating HCV subgenomic RNA. Inhibition of ISRE-mediated transcription of luciferase by actinomycin D also makes HCV replication totally resistant to IFN(alpha). These in vitro studies suggest that activation of IFN-inducible genes is important in mounting a successful antiviral response against HCV.

  11. The distribution characteristics of rare metal elements in surface sediments from four coastal bays on the northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, Shuhong; Li, Jin; Wu, Shuzhuang; Yan, Wen; Huang, Weixia; Miao, Li; Chen, Zhong

    2016-02-01

    The distribution of rare metal elements (Zr, Sn, Ti, Y, Nb, Ta, Ce, La, Nd and Th) in surface sediments from four bays along the northwestern coast of the South China Sea allowed infer their main controlling factors and their mineralization potential as metals placer. The results revealed that their contents in surface sediments are very variable but show a clear geographic regularity. The average content of all elements in those areas decreases from the East to the West, with the minimum value of all elements in Leizhou Bay, the maximum value of Zr, Y, La, Ce, Nd and Th in Zhanjiang Bay, and the maximum values of Sn, Ti, Nb and Ta in Hailing Bay. The relative enrichment of these elements in two easternmost bays (Hailing Bay and Shuidong Bay) are attributed to the southwest alongshore current, which drain and transport terrigenous sediments from the granite region of the South China into these two bays. The correlation results between all element contents and fine sediment fraction (<63 μm) suggested that the main factors controlling the distribution of Ti, Nb and Sn should be the fine fraction of the sediment, but alternatively Zr, Y, La, Ce, Nd and Th are rich in heavy minerals and/or bioclasts, and Ta maybe affected by both. Detail analysis shows that sediments from Hailing Bay may contain abundant zircon, cassiterite, ilmenite (or rutile), xenotime, monazite, niobium tantalite and other rare metal minerals, with a good prospect as a rare metal placer resource, and the zircon, xenotime and monazite may also have good metallogenic prospects in Shuidong Bay and in the local area of Zhangjian Bay.

  12. Finite Element Analysis of the Random Response Suppression of Composite Panels at Elevated Temperatures using Shape Memory Alloy Fibers

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Zhong, Z. W.; Mei, Chuh

    1994-01-01

    A feasibility study on the use of shape memory alloys (SMA) for suppression of the random response of composite panels due to acoustic loads at elevated temperatures is presented. The constitutive relations for a composite lamina with embedded SMA fibers are developed. The finite element governing equations and the solution procedures for a composite plate subjected to combined acoustic and thermal loads are presented. Solutions include: 1) Critical buckling temperature; 2) Flat panel random response; 3) Thermal postbuckling deflection; 4) Random response of a thermally buckled panel. The preliminary results demonstrate that the SMA fibers can completely eliminate the thermal postbuckling deflection and significantly reduce the random response at elevated temperatures.

  13. XPS study of distribution of elements between surface and volume in aluminosilicate catalysts and adsorbents

    SciTech Connect

    Chukin, G.D.; Grishin, S.A.; Kulikov, A.S.; Nefedov, B.K.; Surin, S.A.

    1986-02-01

    X-ray photoelectron spectroscopy (XPS) has been used in an investigation of the distribution of aluminum and sodium on the surface and in the volume of amorphous aluminosilicates. It has been shown that in the Na form of the aluminosilicates, the sodium and aluminum ions are localized preferentially on the surface. When the Na/sup +/ ions are replaced by protons, there is a change in the electronic state of the near-surface atoms in the aluminosilicates. Information on acidic centers that has been obtained by IR spectroscopy is consistent with the XPS data.

  14. Nonlinear Stability and Response of Lifting Surfaces Via Volterra Series

    NASA Technical Reports Server (NTRS)

    Marzocca, Piergiovanni; Librescu, Liviu; Silva, Walter A.

    2001-01-01

    This investigation concerns the time and frequency formulations of non-linear two-dimensional lifting surfaces exposed to an incompressible flow field and subjected to an external pressure pulse. In order to address this problem, Volterra series approach in conjunction with the multidimensional Laplace transform is used. This methodology enabling one to solve the aeroelastic governing equations of lifting surfaces opens the way to connect this methodology with that based on neural networks and NARMAX/NARX networks models. Moreover, this extended way to address this problem constitutes a good basis for treatment of the theory of 3D lifting surfaces.

  15. Development of designer chicken shred with response surface methodology and evaluation of its quality characteristics.

    PubMed

    Reddy, K Jalarama; Jayathilakan, K; Pandey, M C

    2016-01-01

    Meat is considered to be an excellent source of protein, essential minerals, trace elements and vitamins but negative concerns regarding meat consumption and its impact on human health have promoted research into development of novel functional meat products. In the present study Rice bran oil (RBO), and Flaxseed oil (FSO) were used for attaining an ideal lipid profile in the product. The experiment was designed to optimise the RBO and FSO concentration for development of product with ideal lipid profile and maximum acceptability by the application of central composite rotatable design of Response surface methodology (RSM). Levels of RBO and FSO were taken as independent variables and overall acceptability (OAA), n-6 and n-3 fatty acids as responses. Quadratic fit model was found to be suitable for optimising the product. Sample with RBO (20.51 ml) and FSO (2.57 ml) yielded an OAA score of 8.25, 29.54 % of n-6 and 7.70 % of n-3 having n-6/n-3 ratio as 3.8:1. Optimised product was analysed for physico-chemical, sensory and microbial profile during storage at 4 ± 1 °C for 30 days. Increase in the lipid oxidative parameters was observed during storage but it was not significant (p < 0.05). Studies revealed great potential of developing functional poultry products with improved nutritional quality and good shelf stability by incorporating RBO and FSO.

  16. Simulation of Temperature Field Induced by 8-Element Phased Array HIFU Transducer with Concave Spherical Surface

    NASA Astrophysics Data System (ADS)

    Sun, Wujun; Zhang, Ping; Zhang, Xiaojing; Jian, Xiqi; Li, Zhihua

    2011-09-01

    Multi-element High Intensity Focused Ultrasound (HIFU) transducers can change their focal lengths and form multi-foci. In this paper the Westervelt formula and Pennes bio-heat transfer equation have been used along, with the Finite Difference Time Domain (FDTD) method, to study the temperature distribution induced by an 8-element phased array HIFU transducer inside the human body. We evaluated the effects of the gap in the arc between two rings, the frequency of excitation function and pre-focal length on the temperature field. For HIFU therapy, skin burns were caused by high frequency, small pre-focal length, or a big gap between two rings. The focal region may be no longer an ellipsoid due to high frequency. In addition, the actual focal length is slightly different from the pre-focal length.

  17. Method for determining the frequency-response characteristics of an element or system from the system transient output response to a known input function

    NASA Technical Reports Server (NTRS)

    Curfman, Howard J; Gardiner, Robert A

    1950-01-01

    A method is presented for the determination of the frequency-response characteristics of an element or system by utilizing the transient output response to a known but arbitrary input to the system. Since the application of special inputs, such as step functions or sinusoids, is often imperfect or impractical, a method for utilizing arbitrary inputs is desirable. Simple flight-test data may be reduced by this method to give the frequency response of an aircraft. Examples are given as determinations of aircraft frequency responses; however, the method can be applied to any type of dynamic system, such as automatic-control components, vibration-absorption equipment, and many types of instruments. The method requires that the arbitrary input function tend to a finite value after a finite time and that the system or element output be measured as a representative quantity having a static sensitivity. (author)

  18. Automated quadrilateral surface discretization method and apparatus usable to generate mesh in a finite element analysis system

    DOEpatents

    Blacker, Teddy D.

    1994-01-01

    An automatic quadrilateral surface discretization method and apparatus is provided for automatically discretizing a geometric region without decomposing the region. The automated quadrilateral surface discretization method and apparatus automatically generates a mesh of all quadrilateral elements which is particularly useful in finite element analysis. The generated mesh of all quadrilateral elements is boundary sensitive, orientation insensitive and has few irregular nodes on the boundary. A permanent boundary of the geometric region is input and rows are iteratively layered toward the interior of the geometric region. Also, an exterior permanent boundary and an interior permanent boundary for a geometric region may be input and the rows are iteratively layered inward from the exterior boundary in a first counter clockwise direction while the rows are iteratively layered from the interior permanent boundary toward the exterior of the region in a second clockwise direction. As a result, a high quality mesh for an arbitrary geometry may be generated with a technique that is robust and fast for complex geometric regions and extreme mesh gradations.

  19. The Human Antibody Response to the Surface of Mycobacterium tuberculosis

    PubMed Central

    Perley, Casey C.; Frahm, Marc; Click, Eva M.; Dobos, Karen M.; Ferrari, Guido; Stout, Jason E.; Frothingham, Richard

    2014-01-01

    Background Vaccine-induced human antibodies to surface components of Haemophilus influenzae and Streptococcus pneumonia are correlated with protection. Monoclonal antibodies to surface components of Mycobacterium tuberculosis are also protective in animal models. We have characterized human antibodies that bind to the surface of live M. tuberculosis. Methods Plasma from humans with latent tuberculosis (TB) infection (n = 23), active TB disease (n = 40), and uninfected controls (n = 9) were assayed by ELISA for reactivity to the live M. tuberculosis surface and to inactivated M. tuberculosis fractions (whole cell lysate, lipoarabinomannan, cell wall, and secreted proteins). Results When compared to uninfected controls, patients with active TB disease had higher antibody titers to the surface of live M. tuberculosis (Δ = 0.72 log10), whole cell lysate (Δ = 0.82 log10), and secreted proteins (Δ = 0.62 log10), though there was substantial overlap between the two groups. Individuals with active disease had higher relative IgG avidity (Δ = 1.4 to 2.6) to all inactivated fractions. Surprisingly, the relative IgG avidity to the live M. tuberculosis surface was lower in the active disease group than in uninfected controls (Δ = –1.53, p = 0.004). Patients with active disease had higher IgG than IgM titers for all inactivated fractions (ratios, 2.8 to 10.1), but equal IgG and IgM titers to the live M. tuberculosis surface (ratio, 1.1). Higher antibody titers to the M. tuberculosis surface were observed in active disease patients who were BCG-vaccinated (Δ = 0.55 log10, p = 0.008), foreign-born (Δ = 0.61 log10, p = 0.004), or HIV-seronegative (Δ = 0.60 log10, p = 0.04). Higher relative IgG avidity scores to the M. tuberculosis surface were also observed in active disease patients who were BCG-vaccinated (Δ = 1.12, p<0.001) and foreign-born (Δ = 0.87, p = 0.01). Conclusions/Significance Humans

  20. Water-soluble ions and trace elements in surface snow and their potential source regions across northeastern China

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Pu, Wei; Zhang, Xueying; Ren, Yong; Huang, Jianping

    2015-08-01

    We collected 92 snow samples from 13 sites across northeastern China from January 7 to February 15, 2014. The surface snow samples were analyzed for the major water-soluble ions (SO42-, NO3-, F-, Cl-, Na+, K+, Ca2+, Mg2+, and NH4+) and trace element (Al, As, Mn, V, Cd, Cu, Pb, Zn, Fe, Cr, and Ni). The results indicated that the higher concentrations of NO3- and SO42- and the trace elements Zn, Pb, Cd, Ni, and Cu were likely attributable to enhanced local industrial emissions in East Asia especially in China. In addition, snow samples characterized by higher enrichment factors of trace elements (Cu, Cd, As, Zn, Pb) were indicative of an anthropogenic source. Emissions from fossil fuel combustion and biomass burning were likely important contributors to the chemical elements in seasonal snow with long-range transport. On the other hand, the large attribution of K+ appeared in the higher latitude demonstrated that biomass burning was a dominated factor of the chemical species in seasonal snow in the higher latitude of China than that in the lower latitude. Finally, an interannual comparison with the 2010 China snow survey also confirmed the source attributions of chemical speciation in seasonal snow in these regions.

  1. A finite element model technique to determine the mechanical response of a lumbar spine segment under complex loads.

    PubMed

    Tsouknidas, Alexander; Michailidis, Nikoalos; Savvakis, Savvas; Anagnostidis, Kleovoulos; Bouzakis, Konstantinos-Dionysios; Kapetanos, Georgios

    2012-08-01

    This study presents a CT-based finite element model of the lumbar spine taking into account all function-related boundary conditions, such as anisotropy of mechanical properties, ligaments, contact elements, mesh size, etc. Through advanced mesh generation and employment of compound elements, the developed model is capable of assessing the mechanical response of the examined spine segment for complex loading conditions, thus providing valuable insight on stress development within the model and allowing the prediction of critical loading scenarios. The model was validated through a comparison of the calculated force-induced inclination/deformation and a correlation of these data to experimental values. The mechanical response of the examined functional spine segment was evaluated, and the effect of the loading scenario determined for both vertebral bodies as well as the connecting intervertebral disc. PMID:22086145

  2. A finite element model technique to determine the mechanical response of a lumbar spine segment under complex loads.

    PubMed

    Tsouknidas, Alexander; Michailidis, Nikoalos; Savvakis, Savvas; Anagnostidis, Kleovoulos; Bouzakis, Konstantinos-Dionysios; Kapetanos, Georgios

    2012-08-01

    This study presents a CT-based finite element model of the lumbar spine taking into account all function-related boundary conditions, such as anisotropy of mechanical properties, ligaments, contact elements, mesh size, etc. Through advanced mesh generation and employment of compound elements, the developed model is capable of assessing the mechanical response of the examined spine segment for complex loading conditions, thus providing valuable insight on stress development within the model and allowing the prediction of critical loading scenarios. The model was validated through a comparison of the calculated force-induced inclination/deformation and a correlation of these data to experimental values. The mechanical response of the examined functional spine segment was evaluated, and the effect of the loading scenario determined for both vertebral bodies as well as the connecting intervertebral disc.

  3. Trace element geochemistry and surface water chemistry of the Bon Air coal, Franklin County, Cumberland Plateau, southeast Tennessee

    USGS Publications Warehouse

    Shaver, S.A.; Hower, J.C.; Eble, C.F.; McLamb, E.D.; Kuers, K.

    2006-01-01

    surface waters, highest levels of most trace elements occur in mine-adit or mine-dump drainage. Effluent flow rates strongly affect both acidity and trace element levels. Adit drainages where flow is only a trickle have the most acidic waters (pH 3.78-4.80) and highest trace element levels (up to two orders of magnitude higher than in non-mine site waters). Nonetheless, nearly all surface waters have low absolute concentrations of trace elements of environmental concern, and all waters sampled meet U.S. EPA primary drinking water standards and aquatic life criteria for all elements analyzed. Secondary drinking water standards are also met for all parameters except Al, pH, Fe, and Mn, but even in extreme cases (mine waters with pH as low as 3.78 and up to 1243 ppb Al, 6280 ppb Fe, and 721 ppb Mn, and non-mine dam-outflow waters with up to 18,400 ppb Fe and 1540 ppb Mn) downslope attenuation is apparently rapid, as down-drainage plateau-base streams show background levels for all these parameters. ?? 2005 Elsevier B.V. All rights reserved.

  4. Profiling Environmental Chemicals for Activity in the Antioxidant Response Element Signaling Pathway Using a High-Throughput Screening Approach

    EPA Science Inventory

    1 ABSTRACT 2 3 BACKGROUND: Oxidative stress has been implicated in the pathogenesis of a variety 4 of diseases ranging from cancer to neurodegeneration, highlighti.ng the need to identify 5 chemicals that can induce this effect. The antioxidant response element (ARE)...

  5. Profiling Environmental Chemicals in the Antioxidant Response Element Pathway using Quantitative High Throughput Screening (qHTS)

    EPA Science Inventory

    The antioxidant response element (ARE) signaling pathway plays an important role in the amelioration of oxidative stress, which can contribute to a number of diseases, including cancer. We screened 1408 NTP-provided substances in 1536-well qHTS format at concentrations ranging fr...

  6. Sensing element for detection of polar organic vapours on the base of polyaniline-composite - Effect of substrate surface area

    NASA Astrophysics Data System (ADS)

    Olejnik, Robert; Gorakh Babar, Dipak; Slobodian, Petr; Matyas, Jiri

    2016-03-01

    Conductive polymer polyaniline (PANI) was synthesized by oxidative polymerization of aniline hydrochloride as a source of aniline and ammonium persulfate as an oxidation agent. The polymerization process is relatively easy and cheap. The reaction was carried out in presence of polymer substrate, in our case polyethylene terephthalate (PET) as a representative of smooth surface substrate and polyvinylidenfluoride (PVDF) nanofibers membrane as a representative of porous substrate. Both these substrates were covered by polyaniline (PANI) and used as a sensing element for organic vapors detection. The detection was made by measuring and the record of the change of resistivity during adsorption and desorption of saturated vapors. The result shows that sensitivity decreases with increasing polarity of chosen solvent in order N,N- Dimethylformamide (DMF), N,N-Dimethylacetamide (DMAc) and Dimethyl sulfoxide (DMSO). The PANI base sensing element on PVDF substrate improves sensitivity, selectivity and it also has good reversibility and repeatability.

  7. Response Surfaces of Neural Networks Learned Using Bayesian Framework and Its Application to Optimization Problem

    NASA Astrophysics Data System (ADS)

    Takeda, Norio

    We verified the generalization ability of the response surfaces of artificial neural networks (NNs), and that the surfaces could be applied to an engineering-design problem. A Bayesian framework to regularize NNs, which was proposed by Gull and Skilling, can be used to generate NN response surfaces with excellent generalization ability, i.e., to determine the regularizing constants in an objective function minimized during NN learning. This well-generalized NN might be useful to find an optimal solution in the process of response surface methodology (RSM). We, therefore, describe three rules based on the Bayesian framework to update the regularizing constants, utilizing these rules to generate NN response surfaces with noisy teacher data drawn from a typical unimodal or multimodal function. Good generalization ability was achieved with regularized NN response surfaces, even though an update rule including trace evaluation failed to determine the regularizing constants regardless of the response function. We, next, selected the most appropriate update rule, which included eigenvalue evaluation, and then the NN response surface regularized using the update rule was applied to finding the optimal solution to an illustrative engineering-design problem. The NN response surface did not fit the noise in the teacher data, and consequently, it could effectively be used to achieve a satisfactory solution. This may increase the opportunities for using NN in the process of RSM.

  8. Exosomes Derived from HIV-1-infected Cells Contain Trans-activation Response Element RNA*

    PubMed Central

    Narayanan, Aarthi; Iordanskiy, Sergey; Das, Ravi; Van Duyne, Rachel; Santos, Steven; Jaworski, Elizabeth; Guendel, Irene; Sampey, Gavin; Dalby, Elizabeth; Iglesias-Ussel, Maria; Popratiloff, Anastas; Hakami, Ramin; Kehn-Hall, Kylene; Young, Mary; Subra, Caroline; Gilbert, Caroline; Bailey, Charles; Romerio, Fabio; Kashanchi, Fatah

    2013-01-01

    Exosomes are nano-sized vesicles produced by healthy and virus-infected cells. Exosomes derived from infected cells have been shown to contain viral microRNAs (miRNAs). HIV-1 encodes its own miRNAs that regulate viral and host gene expression. The most abundant HIV-1-derived miRNA, first reported by us and later by others using deep sequencing, is the trans-activation response element (TAR) miRNA. In this study, we demonstrate the presence of TAR RNA in exosomes from cell culture supernatants of HIV-1-infected cells and patient sera. TAR miRNA was not in Ago2 complexes outside the exosomes but enclosed within the exosomes. We detected the host miRNA machinery proteins Dicer and Drosha in exosomes from infected cells. We report that transport of TAR RNA from the nucleus into exosomes is a CRM1 (chromosome region maintenance 1)-dependent active process. Prior exposure of naive cells to exosomes from infected cells increased susceptibility of the recipient cells to HIV-1 infection. Exosomal TAR RNA down-regulated apoptosis by lowering Bim and Cdk9 proteins in recipient cells. We found 104–106 copies/ml TAR RNA in exosomes derived from infected culture supernatants and 103 copies/ml TAR RNA in the serum exosomes of highly active antiretroviral therapy-treated patients or long term nonprogressors. Taken together, our experiments demonstrated that HIV-1-infected cells produced exosomes that are uniquely characterized by their proteomic and RNA profiles that may contribute to disease pathology in AIDS. PMID:23661700

  9. Glucose Enhances Basal or Melanocortin-Induced cAMP-Response Element Activity in Hypothalamic Cells.

    PubMed

    Breit, Andreas; Wicht, Kristina; Boekhoff, Ingrid; Glas, Evi; Lauffer, Lisa; Mückter, Harald; Gudermann, Thomas

    2016-07-01

    Melanocyte-stimulating hormone (MSH)-induced activation of the cAMP-response element (CRE) via the CRE-binding protein in hypothalamic cells promotes expression of TRH and thereby restricts food intake and increases energy expenditure. Glucose also induces central anorexigenic effects by acting on hypothalamic neurons, but the underlying mechanisms are not completely understood. It has been proposed that glucose activates the CRE-binding protein-regulated transcriptional coactivator 2 (CRTC-2) in hypothalamic neurons by inhibition of AMP-activated protein kinases (AMPKs), but whether glucose directly affects hypothalamic CRE activity has not yet been shown. Hence, we dissected effects of glucose on basal and MSH-induced CRE activation in terms of kinetics, affinity, and desensitization in murine, hypothalamic mHypoA-2/10-CRE cells that stably express a CRE-dependent reporter gene construct. Physiologically relevant increases in extracellular glucose enhanced basal or MSH-induced CRE-dependent gene transcription, whereas prolonged elevated glucose concentrations reduced the sensitivity of mHypoA-2/10-CRE cells towards glucose. Glucose also induced CRCT-2 translocation into the nucleus and the AMPK activator metformin decreased basal and glucose-induced CRE activity, suggesting a role for AMPK/CRTC-2 in glucose-induced CRE activation. Accordingly, small interfering RNA-induced down-regulation of CRTC-2 expression decreased glucose-induced CRE-dependent reporter activation. Of note, glucose also induced expression of TRH, suggesting that glucose might affect the hypothalamic-pituitary-thyroid axis via the regulation of hypothalamic CRE activity. These findings significantly advance our knowledge about the impact of glucose on hypothalamic signaling and suggest that TRH release might account for the central anorexigenic effects of glucose and could represent a new molecular link between hyperglycaemia and thyroid dysfunction. PMID:27144291

  10. Functional repression of cAMP response element in 6-hydroxydopamine-treated neuronal cells.

    PubMed

    Chalovich, Elisabeth M; Zhu, Jian-hui; Caltagarone, John; Bowser, Robert; Chu, Charleen T

    2006-06-30

    Impaired survival signaling may represent a central mechanism in neurodegeneration. 6-Hydroxydopamine (6-OHDA) is an oxidative neurotoxin used to injure catecholaminergic cells of the central and peripheral nervous systems. Although 6-OHDA elicits phosphorylation of several kinases, downstream transcriptional effects that influence neuronal cell death are less defined. The cAMP response element (CRE) is present in the promoter sequences of several important neuronal survival factors. Treatment of catecholaminergic neuronal cell lines (B65 and SH-SY5Y) with 6-OHDA resulted in repression of basal CRE transactivation. Message levels of CRE-driven genes such as brain-derived neurotrophic factor and the survival factor Bcl-2 were decreased in 6-OHDA-treated cells, but message levels of genes lacking CRE sequences were not affected. Repression of CRE could be reversed by delayed treatment with cAMP several hours after initiation of 6-OHDA injury. Furthermore, restoration of CRE-driven transcription was associated with significant neuroprotection. In contrast to observations in other model systems, the mechanism of CRE repression did not involve decreased phosphorylation of its binding protein CREB. Instead, total CREB and phospho-CREB (pCREB) were increased in the cytoplasm and decreased in the nucleus of 6-OHDA-treated cells. 6-OHDA also decreased nuclear pCREB in dopaminergic neurons of primary mouse midbrain cultures. Co-treatment with cAMP promoted/restored nuclear localization of pCREB in both immortalized and primary culture systems. Increased cytoplasmic pCREB was observed in degenerating human Parkinson/Lewy body disease substantia nigra neurons but not in age-matched controls. Notably, cytoplasmic accumulation of activated upstream CREB kinases has been observed previously in both 6-OHDA-treated cells and degenerating human neurons, supporting a potential role for impaired nuclear import of phosphorylated signaling proteins.

  11. Repression of Wnt/β-catenin response elements by p63 (TP63)

    PubMed Central

    Katoh, Iyoko; Fukunishi, Nahoko; Fujimuro, Masahiro; Kasai, Hirotake; Moriishi, Kohji; Hata, Ryu-Ichiro; Kurata, Shun-ichi

    2016-01-01

    ABSTRACT Submitted: TP63 (p63), a member of the tumor suppressor TP53 (p53) gene family, is expressed in keratinocyte stem cells and well-differentiated squamous cell carcinomas to maintain cellular potential for growth and differentiation. Controversially, activation of the Wnt/β-catenin signaling by p63 (Patturajan M. et al., 2002, Cancer Cells) and inhibition of the target gene expression (Drewelus I. et al., 2010, Cell Cycle) have been reported. Upon p63 RNA-silencing in squamous cell carcinoma (SCC) lines, a few Wnt target gene expression substantially increased, while several target genes moderately decreased. Although ΔNp63α, the most abundant isoform of p63, appeared to interact with protein phosphatase PP2A, neither GSK-3β phosphorylation nor β-catenin nuclear localization was altered by the loss of p63. As reported earlier, ΔNp63α enhanced β-catenin-dependent luc gene expression from pGL3-OT having 3 artificial Wnt response elements (WREs). However, this activation was detectable only in HEK293 cells examined so far, and involved a p53 family-related sequence 5′ to the WREs. In Wnt3-expressing SAOS-2 cells, ΔNp63α rather strongly inhibited transcription of pGL3-OT. Importantly, ΔNp63α repressed WREs isolated from the regulatory regions of MMP7. ΔNp63α-TCF4 association occurred in their soluble forms in the nucleus. Furthermore, p63 and TCF4 coexisted at a WRE of MMP7 on the chromatin, where β-catenin recruitment was attenuated. The combined results indicate that ΔNp63α serves as a repressor that regulates β-catenin-mediated gene expression. PMID:26890356

  12. Finite element comparison of human and Hybrid III responses in a frontal impact.

    PubMed

    Danelson, Kerry A; Golman, Adam J; Kemper, Andrew R; Gayzik, F Scott; Clay Gabler, H; Duma, Stefan M; Stitzel, Joel D

    2015-12-01

    The improvement of finite element (FE) Human Body Models (HBMs) has made them valuable tools for investigating restraint interactions compared to anthropomorphic test devices (ATDs). The objective of this study was to evaluate the effect of various combinations of safety restraint systems on the sensitivity of thoracic injury criteria using matched ATD and Human Body Model (HBM) simulations at two crash severities. A total of seven (7) variables were investigated: 3-point belt with two (2) load limits, frontal airbag, knee bolster airbag, a buckle pretensioner, and two (2) delta-v's - 40kph and 50kph. Twenty four (24) simulations were conducted for the Hybrid III ATD FE model and repeated with a validated HBM for 48 total simulations. Metrics tested in these conditions included sternum deflection, chest acceleration, chest excursion, Viscous Criteria (V*C) criteria, pelvis acceleration, pelvis excursion, and femur forces. Additionally, chest band deflection and rib strain distribution were measured in the HBM for additional restraint condition discrimination. The addition of a frontal airbag had the largest effect on the occupant chest metrics with an increase in chest compression and acceleration but a decrease in excursion. While the THUMS and Hybrid III occupants demonstrated the same trend in the chest compression measurements, there were conflicting results in the V*C, acceleration, and displacement metrics. Similarly, the knee bolster airbag had the largest effect on the pelvis with a decrease in acceleration and excursion. With a knee bolster airbag the simulated occupants gave conflicting results, the THUMS had a decrease in femur force and the ATD had an increase. Preferential use of dummies or HBM's is not debated; however, this study highlights the ability of HBM metrics to capture additional chest response metrics. PMID:26432065

  13. Glucose Enhances Basal or Melanocortin-Induced cAMP-Response Element Activity in Hypothalamic Cells.

    PubMed

    Breit, Andreas; Wicht, Kristina; Boekhoff, Ingrid; Glas, Evi; Lauffer, Lisa; Mückter, Harald; Gudermann, Thomas

    2016-07-01

    Melanocyte-stimulating hormone (MSH)-induced activation of the cAMP-response element (CRE) via the CRE-binding protein in hypothalamic cells promotes expression of TRH and thereby restricts food intake and increases energy expenditure. Glucose also induces central anorexigenic effects by acting on hypothalamic neurons, but the underlying mechanisms are not completely understood. It has been proposed that glucose activates the CRE-binding protein-regulated transcriptional coactivator 2 (CRTC-2) in hypothalamic neurons by inhibition of AMP-activated protein kinases (AMPKs), but whether glucose directly affects hypothalamic CRE activity has not yet been shown. Hence, we dissected effects of glucose on basal and MSH-induced CRE activation in terms of kinetics, affinity, and desensitization in murine, hypothalamic mHypoA-2/10-CRE cells that stably express a CRE-dependent reporter gene construct. Physiologically relevant increases in extracellular glucose enhanced basal or MSH-induced CRE-dependent gene transcription, whereas prolonged elevated glucose concentrations reduced the sensitivity of mHypoA-2/10-CRE cells towards glucose. Glucose also induced CRCT-2 translocation into the nucleus and the AMPK activator metformin decreased basal and glucose-induced CRE activity, suggesting a role for AMPK/CRTC-2 in glucose-induced CRE activation. Accordingly, small interfering RNA-induced down-regulation of CRTC-2 expression decreased glucose-induced CRE-dependent reporter activation. Of note, glucose also induced expression of TRH, suggesting that glucose might affect the hypothalamic-pituitary-thyroid axis via the regulation of hypothalamic CRE activity. These findings significantly advance our knowledge about the impact of glucose on hypothalamic signaling and suggest that TRH release might account for the central anorexigenic effects of glucose and could represent a new molecular link between hyperglycaemia and thyroid dysfunction.

  14. Guidelines for Designing Surface Ion Traps Using the Boundary Element Method

    PubMed Central

    Hong, Seokjun; Lee, Minjae; Cheon, Hongjin; Kim, Taehyun; Cho, Dong-il “Dan”

    2016-01-01

    Ion traps can provide both physical implementation of quantum information processing and direct observation of quantum systems. Recently, surface ion traps have been developed using microfabrication technologies and are considered to be a promising platform for scalable quantum devices. This paper presents detailed guidelines for designing the electrodes of surface ion traps. First, we define and explain the key specifications including trap depth, q-parameter, secular frequency, and ion height. Then, we present a numerical-simulation-based design procedure, which involves determining the basic assumptions, determining the shape and size of the chip, designing the dimensions of the radio frequency (RF) electrode, and analyzing the direct current (DC) control voltages. As an example of this design procedure, we present a case study with tutorial-like explanations. The proposed design procedure can provide a practical guideline for designing the electrodes of surface ion traps. PMID:27136559

  15. Oxidation of elemental mercury by chlorine: Gas phase, Surface,and Photo-induced reaction pathways

    SciTech Connect

    Yan, Nai-Qiang; Liu, Shou-Heng; Chang, Shih-Ger

    2004-10-22

    Accurate oxidation rate constants of mercury gas are needed for determining its dispersion and lifetime in the atmosphere. They would also help in developing a technology for the control of mercury emissions from coal-fired power plants. However, it is difficult to establish the accurate rate constants primarily due to the fact that mercury easily adsorbs on solid surface and its reactions can be catalyzed by the surface. We have demonstrated a procedure that allows the determination of gas phase, surface-induced, and photo-induced contributions in the kinetic study of the oxidation of mercury by chlorine gas. The kinetics was studied using reactors with various surface to volume ratios. The effect of the surface and the photo irradiation on the reaction was taken into consideration. The pressure dependent study revealed that the gas phase oxidation was a three-body collision process. The third order rate constant was determined to be 7.5({+-}0.2) x 10{sup -39} mL{sup 2} molecules{sup -2}s{sup -1} with N{sub 2} as the third body at 297 {+-} 1 K. The surface induced reaction on quartz window was second order and the rate constant was 2.7 x 10{sup -17} mL{sup 2} molecules{sup -1} cm{sup -2} sec. Meanwhile, the 253.7 nm photon employed for mercury detection was found to accelerate the reaction. The utilization efficiency of 253.7 nm photon for Hg{sup 0} oxidation was 6.7 x 10{sup -4} molecules photon{sup -1} under the conditions employed in this study.

  16. Third element effect in the surface zone of Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Airiskallio, E.; Nurmi, E.; Heinonen, M. H.; Väyrynen, I. J.; Kokko, K.; Ropo, M.; Punkkinen, M. P. J.; Pitkänen, H.; Alatalo, M.; Kollár, J.; Johansson, B.; Vitos, L.

    2010-01-01

    The third element effect to improve the high temperature corrosion resistance of the low-Al Fe-Cr-Al alloys is suggested to involve a mechanism that boosts the recovering of the Al concentration to the required level in the Al-depleted zone beneath the oxide layer. We propose that the key factor in this mechanism is the coexistent Cr depletion that helps to maintain a sufficient Al content in the depleted zone. Several previous experiments related to our study support that conditions for such a mechanism to be functional prevail in real oxidation processes of Fe-Cr-Al alloys.

  17. Special element approach for calculating the vibratory response of adhesively bonded and composite structures

    NASA Astrophysics Data System (ADS)

    Kim, N. E.; Griffin, J. H.

    1994-02-01

    An approach is presented that may be used to calculate the natural frequencies and loss factors of composite sandwich beams or beams containing adhesively bonded joints. The approach uses special finite elements to represent either composite or joint elements and the modal strain energy method to calculate the loss factor for each vibratory mode of interest. The special element represents a section of the composite beam or the overlap joint as an element with four nodes. Its properties are calculated by using a generalization of the shape function concept from finite elements in which the shape function (displacement fields) in the special elements are determined by performing static stress analysis on the special element's substructure. The resulting special element has only a small number of degrees of freedom and, yet, accurately represents the geometrically complex substructure. Results obtained using this approach on sandwich beams compare well with an analytical solution published in the literature. In addition, it correlates reasonably well with data taken from tests on adhesively bonded beams.

  18. Monte-Carlo gamma response simulation of fast/thermal neutron interactions with soil elements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil elemental analysis using characteristic gamma rays induced by neutrons is an effective method of in situ soil content determination. The nuclei of soil elements irradiated by neutrons issue characteristic gamma rays due to both inelastic neutron scattering (e.g., Si, C) and thermal neutron capt...

  19. Penalty-finite element analysis of time-dependent two-dimensional free surface film flows

    NASA Astrophysics Data System (ADS)

    Kheshgi, H. S.; Scriven, L. E.

    The Navier-Stokes system with shear-free balanced normal stress and with kinematic boundary conditions at the free surface, which governs the flow of incompressible Newtonian liquid films, is presently solved by the penalty/Galerkin/FEM technique, employing both a tesselation that deforms with the free surface and an implicit time domain method. Results are given for the case of transient flow out of a coating slot, and a more brief presentation of results is made for the cases of the capillary leveling of a disturbed film, the damping of standing waves, and evolving disturbances in a film flowing down an inclined plane.

  20. Response surfaces for CO2 leakage from geologic storage along abandoned wellbores

    NASA Astrophysics Data System (ADS)

    Jordan, A.; Carey, J. W.; Pawar, R. J.; Stauffer, P. H.

    2011-12-01

    The storage of carbon dioxide (CO2) in geologic reservoirs that have previously been drilled for oil and gas exploration is under investigation worldwide as an option for reducing the amount of anthropogenic carbon introduced to the atmosphere. Reservoirs that have already been tapped for hydrocarbon production have several benefits over development of new sites: they tend to be geologically well-understood, with existing wellbore data to help further characterize the local geologic framework; are known to be conducive to trapping buoyant or pressurized fluids; may have infrastructure in place; and are likely to be already impacted ecologically as compared to pristine sites. One downside to using depleted hydrocarbon reservoirs is the potential for CO2 leakage along pre-existing wellbores that were either not designed for CO2 sequestration or have been improperly plugged and abandoned. The primary goal of this study is to develop estimates of possible wellbore leakage rates of CO2 from storage reservoirs to the surface and/or into overlaying aquifers, as a function of wellbore properties and the surrounding geologic framework. The Finite Element Heat and Mass transfer code (FEHM) was used to perform Monte Carlo simulations of multiphase flow along wellbores across a wide range of geologic and wellbore parameters. Several wellbore scenarios were studied, including a simple wellbore between the CO2 storage reservoir and the surface; a wellbore intersecting a saline aquifer ("thief zone"); and a wellbore intersecting both a thief zone and a freshwater aquifer. The Problem Solving environment for Uncertainty Analysis and Design Exploration (PSUADE) software was used to analyze results and produce response surfaces for the estimation of wellbore flow rate as a function of the primary factors that influence leakage. These results will be used to develop abstractions for leakage rates to be incorporated in performance assessments of geologic CO2 storage, which will help

  1. Response of the surface tropical Atlantic Ocean to wind forcing

    NASA Astrophysics Data System (ADS)

    Castellanos, Paola; Pelegrí, Josep L.; Campos, Edmo J. D.; Rosell-Fieschi, Miquel; Gasser, Marc

    2015-05-01

    We use 10 years of satellite data (sea level pressure, surface winds and absolute dynamic topography [ADT]) together with Argo-inferred monthly-mean values of near-surface velocity and water transport, to examine how the tropical system of near-surface zonal currents responds to wind forcing. The data is analyzed using complex Hilbert empirical orthogonal functions, confirming that most of the variance has annual periodicity, with maximum amplitudes in the region spanned by the seasonal displacement of the Inter-Tropical Convergence Zone (ITCZ). The ADT mirrors the shape of the upper isopycnals, hence becoming a good indicator of the amount of water stored in the upper ocean. Within about 3° from the Equator, where the Coriolis force is small, there is year-long meridional Ekman-transport divergence that would lead to the eastward transport of the Equatorial Undercurrent and its northern and southern branches. Beyond 3° of latitude, and at least as far as 20°, the convergence of the Ekman transport generally causes a poleward positive ADT gradient, which sustains the westward South Equatorial Current (SEC). The sole exception occurs in summer, between 8°N and 12°N, when an Ekman-transport divergence develops and depletes de amount of surface water, resulting in an ADT ridge-valley system which reverses the ADT gradient and drives the eastward North Equatorial Countercurrent (NECC) at latitudes 4-9°N; in late fall, divergence ceases and the NECC drains the ADT ridge, so the ADT gradient again becomes positive and the SEC reappears. The seasonal evolution of a tilted ITCZ controls the surface water fluxes: the wind-induced transports set the surface divergence-convergence, which then drive the ADT and, through the ADT gradients, create the geostrophic jets that close the water balance.

  2. Elemental concentrations and inorganic isotopic ratios in surface snow along the route to Dome Fuji, Antarctica

    NASA Astrophysics Data System (ADS)

    Hirabayashi, M.; Nakazawa, F.; Azuma, K. G.; Motoyama, H.

    2015-12-01

    Snow ice sample in Antarctica contains particulate matter. Particulates originate from continent, volcano, sea, space, and organism. The particulate matter of continental origin contains many elements from minerals and rocks. The isotopic ratio of an element reflects the origin and the history of the particle. Since the isotopic ratio of inorganic species depends on the source, the information about the source contribution of particulate matter can be estimated by analyzing the isotopic ratios of inorganic species. In this research, concentrations of inorganic species and isotopic ratios of inorganic species (Ca, Sr, Nd) in snow collected on the route form coastal area to Dome Fuji station in Antarctica were analyzed. The snow samples were collected along ca. 1000 km traverse route from Mikaeridai (S16; 69°01'S, 40°03'E, 590 m) to Dome Fuji station (77°19'S, 39°42'E, 3810 m) by the Japan Antarctica research expedition. Those samples were collected in the 2007/2008 and 2009/2010 austral summer. The samples were transported to Japan without thawing. The quantitative analyses of inorganic species were measured using ICP quadrupole type mass spectrometer. The isotopic ratios of isolated inorganic species were measured using ICP magnetic field type mass spectrometer. Further results and discussion about the behavior and origin of sulfur species in snow will be presented.

  3. Mineralogical analyses of surface sediments in the Antarctic Dry Valleys: coordinated analyses of Raman spectra, reflectance spectra and elemental abundances.

    PubMed

    Bishop, Janice L; Englert, Peter A J; Patel, Shital; Tirsch, Daniela; Roy, Alex J; Koeberl, Christian; Böttger, Ute; Hanke, Franziska; Jaumann, Ralf

    2014-12-13

    Surface sediments at Lakes Fryxell, Vanda and Brownworth in the Antarctic Dry Valleys (ADV) were investigated as analogues for the cold, dry environment on Mars. Sediments were sampled from regions surrounding the lakes and from the ice cover on top of the lakes. The ADV sediments were studied using Raman spectra of individual grains and reflectance spectra of bulk particulate samples and compared with previous analyses of subsurface and lakebottom sediments. Elemental abundances were coordinated with the spectral data in order to assess trends in sediment alteration. The surface sediments in this study were compared with lakebottom sediments (Bishop JL et al. 2003 Int. J. Astrobiol. 2, 273-287 (doi:10.1017/S1473550403001654)) and samples from soil pits (Englert P et al. 2013 In European Planetary Science Congress, abstract no. 96; Englert P et al. 2014 In 45th Lunar and Planetary Science Conf., abstract no. 1707). Feldspar, quartz and pyroxene are common minerals found in all the sediments. Minor abundances of carbonate, chlorite, actinolite and allophane are also found in the surface sediments, and are similar to minerals found in greater abundance in the lakebottom sediments. Surface sediment formation is dominated by physical processes; a few centimetres below the surface chemical alteration sets in, whereas lakebottom sediments experience biomineralization. Characterizing the mineralogical variations in these samples provides insights into the alteration processes occurring in the ADV and supports understanding alteration in the cold and dry environment on Mars. PMID:25368345

  4. Mineralogical analyses of surface sediments in the Antarctic Dry Valleys: coordinated analyses of Raman spectra, reflectance spectra and elemental abundances.

    PubMed

    Bishop, Janice L; Englert, Peter A J; Patel, Shital; Tirsch, Daniela; Roy, Alex J; Koeberl, Christian; Böttger, Ute; Hanke, Franziska; Jaumann, Ralf

    2014-12-13

    Surface sediments at Lakes Fryxell, Vanda and Brownworth in the Antarctic Dry Valleys (ADV) were investigated as analogues for the cold, dry environment on Mars. Sediments were sampled from regions surrounding the lakes and from the ice cover on top of the lakes. The ADV sediments were studied using Raman spectra of individual grains and reflectance spectra of bulk particulate samples and compared with previous analyses of subsurface and lakebottom sediments. Elemental abundances were coordinated with the spectral data in order to assess trends in sediment alteration. The surface sediments in this study were compared with lakebottom sediments (Bishop JL et al. 2003 Int. J. Astrobiol. 2, 273-287 (doi:10.1017/S1473550403001654)) and samples from soil pits (Englert P et al. 2013 In European Planetary Science Congress, abstract no. 96; Englert P et al. 2014 In 45th Lunar and Planetary Science Conf., abstract no. 1707). Feldspar, quartz and pyroxene are common minerals found in all the sediments. Minor abundances of carbonate, chlorite, actinolite and allophane are also found in the surface sediments, and are similar to minerals found in greater abundance in the lakebottom sediments. Surface sediment formation is dominated by physical processes; a few centimetres below the surface chemical alteration sets in, whereas lakebottom sediments experience biomineralization. Characterizing the mineralogical variations in these samples provides insights into the alteration processes occurring in the ADV and supports understanding alteration in the cold and dry environment on Mars.

  5. Development of an alpha scattering instrument for heavy element detection in surface materials

    NASA Technical Reports Server (NTRS)

    Turkevich, A. L.; Economou, T.; Blume, E.; Anderson, W.

    1974-01-01

    The development and characteristics of a portable instrument for detecting and measuring the amounts of lead in painted surfaces are discussed. The instrument is based on the ones used with the alpha scattering experiment on the Surveyor lunar missions. The principles underlying the instrument are described. It is stated that the performance tests of the instrument were satisfactory.

  6. Micro-X-Ray Fluorescence Spectrometry of the Surface Elemental Composition of Vegetative Parts and Fruiting Bodies of Lichenized Teloschistaceae Fungi

    NASA Astrophysics Data System (ADS)

    Biazrov, L. G.; Pelgunova, L. A.

    2016-01-01

    The elemental composition and atomic mass ratios (%) on the surface of vegetative and generative parts of crustose Caloplaca cerina and foliose Xanthoria parietina lichen thalli collected from the same tree trunk were measured using micro-x-ray fluorescence spectrometry. The atomic mass fractions for half of the elements (of 21 identified) were significantly higher on the surfaces of fruiting bodies (apothecia) than on vegetative parts of thalli of both species. The atomic mass fractions of most elements were much greater on the surfaces of fruiting bodies and vegetative parts of the foliose species than on the crustose species.

  7. Flow patterns and transport in Rayleigh surface acoustic wave streaming: combined finite element method and raytracing numerics versus experiments.

    PubMed

    Frommelt, Thomas; Gogel, Daniel; Kostur, Marcin; Talkner, Peter; Hänggi, Peter; Wixforth, Achim

    2008-10-01

    This work presents an approach for determining the streaming patterns that are generated by Rayleigh surface acoustic waves in arbitrary 3-D geometries by finite element method (FEM) simulations. An efficient raytracing algorithm is applied on the acoustic subproblem to avoid the unbearable memory demands and computational time of a conventional FEM acoustics simulation in 3-D. The acoustic streaming interaction is modeled by a body force term in the Stokes equation. In comparisons between experiments and simulated flow patterns, we demonstrate the quality of the proposed technique. PMID:18986877

  8. High-order spectral/hp element discretisation for reaction–diffusion problems on surfaces: Application to cardiac electrophysiology☆

    PubMed Central

    Cantwell, Chris D.; Yakovlev, Sergey; Kirby, Robert M.; Peters, Nicholas S.; Sherwin, Spencer J.

    2014-01-01

    We present a numerical discretisation of an embedded two-dimensional manifold using high-order continuous Galerkin spectral/hp elements, which provide exponential convergence of the solution with increasing polynomial order, while retaining geometric flexibility in the representation of the domain. Our work is motivated by applications in cardiac electrophysiology where sharp gradients in the solution benefit from the high-order discretisation, while the computational cost of anatomically-realistic models can be significantly reduced through the surface representation and use of high-order methods. We describe and validate our discretisation and provide a demonstration of its application to modelling electrochemical propagation across a human left atrium. PMID:24748685

  9. Effects of surface viscoelasticity on cellular responses of endothelial cells

    PubMed Central

    Hosseini, Motahare-Sadat; Katbab, Ali Asghar

    2014-01-01

    Background: One area of nanoscience deals with nanoscopic interactions between nanostructured materials and biological systems. To elucidate the effects of the substrate surface morphology and viscoelasticity on cell proliferation, fractal analysis was performed on endothelial cells cultured on nanocomposite samples based on silicone rubber (SR) and various concentrations of organomodified nanoclay (OC). Methods: The nanoclay/SR ratio was tailored to enhance cell behavior via changes in sample substrate surface roughness and viscoelasticity. Results: Surface roughness of the cured SR filled with negatively-charged nanosilicate layers had a greater effect than elasticity on cell growth. The surface roughness of SR nanocomposite samples increased with increasing the OC content, leading to enhanced cell growth and extracellular matrix (ECM) remodeling. This was consistent with the decrease in SR segmental motions and damping factor as the primary viscoelastic parameters by the nanosilicate layers with increasing clay concentrations. Conclusions: The inclusion of clay nanolayers affected the growth and behavior of endothelial cells on microtextured SR. PMID:26989733

  10. Insulators, not Polycomb response elements, are required for long-range interactions between Polycomb targets in Drosophila melanogaster.

    PubMed

    Li, Hua-Bing; Müller, Martin; Bahechar, Ilham Anne; Kyrchanova, Olga; Ohno, Katsuhito; Georgiev, Pavel; Pirrotta, Vincenzo

    2011-02-01

    The genomic binding sites of Polycomb group (PcG) complexes have been found to cluster, forming Polycomb "bodies" or foci in mammalian or fly nuclei. These associations are thought to be driven by interactions between PcG complexes and result in enhanced repression. Here, we show that a Polycomb response element (PRE) with strong PcG binding and repressive activity cannot mediate trans interactions. In the case of the two best-studied interacting PcG targets in Drosophila, the Mcp and the Fab-7 regulatory elements, we find that these associations are not dependent on or caused by the Polycomb response elements they contain. Using functional assays and physical colocalization by in vivo fluorescence imaging or chromosome conformation capture (3C) methods, we show that the interactions between remote copies of Mcp or Fab-7 elements are dependent on the insulator activities present in these elements and not on their PREs. We conclude that insulator binding proteins rather than PcG complexes are likely to be the major determinants of the long-range higher-order organization of PcG targets in the nucleus. PMID:21135119

  11. The GNSS Reflectometry Response to the Ocean Surface

    NASA Astrophysics Data System (ADS)

    Chang, Paul; Jelenak, Zorana; Soisuvarn, Seubson; Said, Faozi

    2016-04-01

    Global Navigation Satellite System - Reflectometry (GNSS-R) exploits signals of opportunity from the Global Navigation Satellite System (GNSS). GNSS transmitters continuously transmit navigation signals at L-band toward the earth's surface. The scattered power reflected off the earth's surface can be sensed by specially designed GNSS-R receivers. The reflected signal can then be used to glean information about the surface of the earth, such as ocean surface roughness, snow depth, sea ice extent, and soil moisture. The use of GNSS-R for ocean wind retrievals was first demonstrated from aircraft. On July 8 2014, the TechDemoSat-1 satellite (TDS-1) was launched by Surrey Satellite Technology, Ltd as a technology risk reduction mission into sun-synchronous orbit. This paper investigates the GNSS-R measurements collected by the Space GNSS Receiver-Remote Sensing Instrument (SGR-ReSI) on board the TDS-1 satellite. The sensitivity of the SGR-ReSI measurements to the ocean surface winds and waves are characterized. The effects of sea surface temperature, wind direction, and rain are also investigated. The SGR-ReSI measurements exhibited sensitivity through the entire range of wind speeds sampled in this dataset, up to 35 m/s. A significant dependence on the larger waves was observed for winds < 6 m/s. Additionally, an interesting dependence on SST was observed where the slope of the SGR-ReSI measurements is positive for winds < 5 m/s and reverses for winds > 5 m/s. There appeared to be very little wind direction signal, and investigation of the rain impacts found no apparent sensitivity in the data. These results are shown through the analysis of global statistics and examination of a few case studies. This released SGR-ReSI dataset provided the first opportunity to comprehensively investigate the sensitivity of satellite-based GNSS-R measurements to various ocean surface parameters. The upcoming NASA's Cyclone Global Navigation Satellite System (CYGNSS) satellite

  12. Reconstruction of surfaces from mixed hydrocarbon and PEG components in water: responsive surfaces aid fouling release.

    PubMed

    Cho, Youngjin; Sundaram, Harihara S; Finlay, John A; Dimitriou, Michael D; Callow, Maureen E; Callow, James A; Kramer, Edward J; Ober, Christopher K

    2012-06-11

    Coatings derived from surface active block copolymers (SABCs) having a combination of hydrophobic aliphatic (linear hydrocarbon or propylene oxide-derived groups) and hydrophilic poly(ethlyene glycol) (PEG) side chains have been developed. The coatings demonstrate superior performance against protein adsorption as well as resistance to biofouling, providing an alternative to coatings containing fluorinated side chains as the hydrophobe, thus reducing the potential environmental impact. The surfaces were examined using dynamic water contact angle, captive air-bubble contact angle, atomic force microscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure analysis. The PS(8K)-b-P(E/B)(25K)-b-PI(10K) triblock copolymer precursor (K3) initially dominated the dry surface. In contrast to previous studies with mixed fluorinated/PEG surfaces, these new materials displayed significant surface changes after exposure to water that allowed fouling resistant behavior. PEG groups buried several nanometers below the surface in the dry state were able to occupy the coating surface after placement in water. The resulting surface exhibits a very low contact angle and good antifouling properties that are very different from those of K3. The surfaces are strongly resistant to protein adsorption using bovine serum albumin as a standard protein challenge. Biofouling assays with sporelings of the green alga Ulva and cells of the diatom Navicula showed the level of adhesion was significantly reduced relative to that of a PDMS standard and that of the triblock copolymer precursor of the SABCs.

  13. Isolation of a non-genomic origin fluoroquinolone responsive regulatory element using a combinatorial bioengineering approach

    PubMed Central

    Srivastava, Santosh Kumar; Iyer, V. Rajesh; Ghosh, Tamoghna; Lambadi, Paramesh Ramulu; Pathania, Ranjana; Navani, Naveen Kumar

    2016-01-01

    Advances in chemical biology have led to selection of synthetic functional nucleic acids for in vivo applications. Discovery of synthetic nucleic acid regulatory elements has been a long-standing goal of chemical biologists. Availability of vast genome level genetic resources has motivated efforts for discovery and understanding of inducible synthetic genetic regulatory elements. Such elements can lead to custom-design of switches and sensors, oscillators, digital logic evaluators and cell–cell communicators. Here, we describe a simple, robust and universally applicable module for discovery of inducible gene regulatory elements. The distinguishing feature is the use of a toxic peptide as a reporter to suppress the background of unwanted bacterial recombinants. Using this strategy, we show that it is possible to isolate genetic elements of non-genomic origin which specifically get activated in the presence of DNA gyrase A inhibitors belonging to fluoroquinolone (FQ) group of chemicals. Further, using a system level genetic resource, we prove that the genetic regulation is exerted through histone-like nucleoid structuring (H-NS) repressor protein. Till date, there are no reports of in vivo selection of non-genomic origin inducible regulatory promoter like elements. Our strategy opens an uncharted route to discover inducible synthetic regulatory elements from biologically-inspired nucleic acid sequences. PMID:26837578

  14. The Use of Direct Solver in Vector Finite Element Modeling for Calculating 3-D Magnetotelluric Responses

    NASA Astrophysics Data System (ADS)

    Prihantoro, Rudy; Sutarno, Doddy; Nurhasan

    2016-08-01

    In this work, we seek numerical solution of 3-D Magnetotelluric (MT) using edge- based finite element method. This approach is a variant of standard finite element method and commonly referred as vector finite-element (VFE) method. Nonphysical solutions usually occurred when the solution is sought using standard finite element which is a node based element. Vector finite element attempt to overcome those nonphysical solutions by using the edges of the element as vector basis. The proposed approach on solving second order Maxwell differential equation of 3-D MT is using direct solver rather than iterative method. Therefore, divergence correction to accelerate the rate of convergence for its iterative solution is no longer needed. The utilization of direct solver has been verified previously for correctness by comparing the resulting solution to those given by analytical solution, as well as the solution come from the other numerical methods, for earth layered model, 2-D models and COMMEMI 3D-2 model. In this work, further verification resulted from recent comparison model of Dublin Test Model 1 (DTM1) is presented.

  15. DNase I hypersensitivity sites and nuclear protein binding on the fatty acid synthase gene: identification of an element with properties similar to known glucose-responsive elements.

    PubMed Central

    Foufelle, F; Lepetit, N; Bosc, D; Delzenne, N; Morin, J; Raymondjean, M; Ferré, P

    1995-01-01

    We have shown previously that fatty acid synthase (FAS) gene expression is positively regulated by glucose in rat adipose tissue and liver. In the present study, we have identified in the first intron of the gene a sequence closely related to known glucose-responsive elements such as in the L-pyruvate kinase and S14 genes, including a putative upstream stimulatory factor/major late transcription factor (USF/MLTF) binding site (E-box) (+ 292 nt to + 297 nt). Location of this sequence corresponds to a site of hypersensitivity to DNase I which is present in the liver but not in the spleen. Moreover, using this information from a preliminary report of the present work, others have shown that a + 283 nt to + 303 nt sequence of the FAS gene can confer glucose responsiveness to a heterologous promoter. The protein binding to this region has been investigated in vitro by a combination of DNase I footprinting and gel-retardation experiments with synthetic oligonucleotides and known nuclear proteins. DNase I footprinting experiments using a + 161 nt to + 405 nt fragment of the FAS gene demonstrate that a region from + 290 nt to + 316 nt is protected by nuclear extracts from liver and spleen. This region binds two ubiquitous nuclear factors, USF/MLTF and the CAAT-binding transcription factor/nuclear factor 1 (CTF/NF1). Binding of these factors is similar in nuclear extracts from liver which does or does not express the FAS gene as observed for glucose-responsive elements in the L-pyruvate kinase and S14 genes. This suggests a posttranslational modification of a factor of the complex after glucose stimulation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7772036

  16. DNase I hypersensitivity sites and nuclear protein binding on the fatty acid synthase gene: identification of an element with properties similar to known glucose-responsive elements.

    PubMed

    Foufelle, F; Lepetit, N; Bosc, D; Delzenne, N; Morin, J; Raymondjean, M; Ferré, P

    1995-06-01

    We have shown previously that fatty acid synthase (FAS) gene expression is positively regulated by glucose in rat adipose tissue and liver. In the present study, we have identified in the first intron of the gene a sequence closely related to known glucose-responsive elements such as in the L-pyruvate kinase and S14 genes, including a putative upstream stimulatory factor/major late transcription factor (USF/MLTF) binding site (E-box) (+ 292 nt to + 297 nt). Location of this sequence corresponds to a site of hypersensitivity to DNase I which is present in the liver but not in the spleen. Moreover, using this information from a preliminary report of the present work, others have shown that a + 283 nt to + 303 nt sequence of the FAS gene can confer glucose responsiveness to a heterologous promoter. The protein binding to this region has been investigated in vitro by a combination of DNase I footprinting and gel-retardation experiments with synthetic oligonucleotides and known nuclear proteins. DNase I footprinting experiments using a + 161 nt to + 405 nt fragment of the FAS gene demonstrate that a region from + 290 nt to + 316 nt is protected by nuclear extracts from liver and spleen. This region binds two ubiquitous nuclear factors, USF/MLTF and the CAAT-binding transcription factor/nuclear factor 1 (CTF/NF1). Binding of these factors is similar in nuclear extracts from liver which does or does not express the FAS gene as observed for glucose-responsive elements in the L-pyruvate kinase and S14 genes. This suggests a posttranslational modification of a factor of the complex after glucose stimulation.

  17. Four p53 DNA-binding domain peptides bind natural p53-response elements and bend the DNA.

    PubMed Central

    Balagurumoorthy, P; Sakamoto, H; Lewis, M S; Zambrano, N; Clore, G M; Gronenborn, A M; Appella, E; Harrington, R E

    1995-01-01

    Recent structural studies of the minimal core DNA-binding domain of p53 (p53DBD) complexed to a single consensus pentamer sequence and of the isolated p53 tetramerization domain have provided valuable insights into their functions, but many questions about their interacting roles and synergism remain unanswered. To better understand these relationships, we have examined the binding of the p53DBD to two biologically important full-response elements (the WAF1 and ribosomal gene cluster sites) by using DNA circularization and analytical ultracentrifugation. We show that the p53DBD binds DNA strongly and cooperatively with p53DBD to DNA binding stoichiometries of 4:1. For the WAF1 element, the mean apparent Kd is (8.3 +/- 1.4) x 10(-8) M, and no intermediate species of lower stoichiometries can be detected. We show further that complex formation induces an axial bend of at least 60 degrees in both response elements. These results, taken collectively, demonstrate that p53DBD possesses the ability to direct the formation of a tight nucleoprotein complex having the same 4:1 DNA-binding stoichiometry as wild-type p53 which is accompanied by a substantial conformational change in the response-element DNA. This suggests that the p53DBD may play a role in the tetramerization function of p53. A possible role in this regard is proposed. Images Fig. 2 Fig. 4 PMID:7567980

  18. The MYC 3′ Wnt-Responsive Element Drives Oncogenic MYC Expression in Human Colorectal Cancer Cells

    PubMed Central

    Rennoll, Sherri A.; Eshelman, Melanie A.; Raup-Konsavage, Wesley M.; Kawasawa, Yuka Imamura; Yochum, Gregory S.

    2016-01-01

    Mutations in components of the Wnt/β-catenin signaling pathway drive colorectal cancer (CRC) by deregulating expression of downstream target genes including the c-MYC proto-oncogene (MYC). The critical regulatory DNA enhancer elements that control oncogenic MYC expression in CRC have yet to be fully elucidated. In previous reports, we correlated T-cell factor (TCF) and β-catenin binding to the MYC 3′ Wnt responsive DNA element (MYC 3′ WRE) with MYC expression in HCT116 cells. Here we used CRISPR/Cas9 to determine whether this element is a critical driver of MYC. We isolated a clonal population of cells that contained a deletion of a single TCF binding element (TBE) within the MYC 3′ WRE. This deletion reduced TCF/β-catenin binding to this regulatory element and decreased MYC expression. Using RNA-Seq analysis, we found altered expression of genes that regulate metabolic processes, many of which are known MYC target genes. We found that 3′ WRE-Mut cells displayed a reduced proliferative capacity, diminished clonogenic growth, and a decreased potential to form tumors in vivo. These findings indicate that the MYC 3′ WRE is a critical driver of oncogenic MYC expression and suggest that this element may serve as a therapeutic target for CRC. PMID:27223305

  19. Sensing of human plasma fibrinogen on polished, chemically etched and carbon treated titanium surfaces by diffractive optical element based sensor.

    PubMed

    Silvennoinen, Raimo; Vetterl, Vladimir; Hason, Stanislav; Tuononen, Heikki; Silvennoinen, Martti; Myller, Kari; Cvrcek, Ladislav; Vanek, Jiri; Prachar, Patrik

    2008-07-01

    Adsorption of human plasma fibrinogen (HPF) on 6 differently treated titanium samples (polished, polished and etched, and 4 titanium carbide coatings samples produced by using plasma-enhanced chemical vapour deposition (PECVD) method) is investigated by using diffractive optical element (DOE) sensor. Permittivity (susceptibility) change and fluctuation in optical roughness (R(opt)) of treated titanium surface in the presence of background electrolyte without and with HPF molecules are sensed by using DOE sensor and optical ellipsometry. Correlation between transmitted light and thickness of molecule layer was found. The findings allow to sense temporal organization and severity of adsorption of nano-scale HPF molecules on polished, on polished and etched, and on titanium carbide surface.

  20. Investigations of Effects of Surface Temperature and Single Roughness Elements on Boundary-Layer Transition

    NASA Technical Reports Server (NTRS)

    Liepmann, Hans W; Fila, Gertrude H

    1947-01-01

    The laminar boundary layer and the position of the transition point were investigated on a heated flat plate. It was found that the Reynolds number of transition decreased as the temperature of the plate is increased. It is shown from simple qualitative analytical considerations that the effect of variable viscosity in the boundary layer due to the temperature difference produces a velocity profile with an inflection point if the wall temperature is higher than the free-stream temperature. This profile is confirmed by measurements. The instability of inflection-point profiles is discussed. Studies of the flow in the wake of large, two-dimensional roughness elements are presented. It is shown that a boundary-layer can separate and reattach itself to the wall without having transition take place.

  1. Distribution and variation of arsenic in Wisconsin surface soils, with data on other trace elements

    USGS Publications Warehouse

    Stensvold, Krista A.

    2012-01-01

    Soils with sandy glacial outwash as a parent material have a lower median arsenic concentration (1.0 mg/kg) than soils forming in other parent materials (1.5 to 3.0 mg/kg). Soil texture and drainage category also influence median arsenic concentration. Finer grained soils have a higher observed range of concentrations. For loamy and loess-dominated soil groups, drainage category influences the median arsenic concentration and observed range of values, but a consistent relationship within the data is not apparent. Statistical analysis of the 16 other elements are presented in this report, but the relationships of concentrations to soil properties or geographic areas were not examined.

  2. Sea surface temperature variation linked to elemental mercury concentrations measured on Mauna Loa

    NASA Astrophysics Data System (ADS)

    Carbone, F.; Landis, M. S.; Gencarelli, C. N.; Naccarato, A.; Sprovieri, F.; De Simone, F.; Hedgecock, I. M.; Pirrone, N.

    2016-07-01

    The Hg0 time series recorded at the Mauna Loa Observatory (MLO) in Hawaii between 2002 and 2009 has been analyzed using Empirical Mode Decomposition. This technique has been used in numerous contexts in order to identify periodical variations in time series data. The periodicities observed in the tropical Pacific sea surface temperature (SST), through the data collected from five buoys, are also observed in Hg0 concentrations and the relative humidity measured at the MLO. The lag times in the observed periodicities are related to the position of the buoys with respect to the measurement site. This demonstrates a direct link between climatological phenomena, in this case SST, and measured Hg0 and reflects the influence of ocean SST on Hg0 evasion. This is the first long-term experimental evidence of such a direct effect on Hg0 evasion from the oceanic surface driven by temperature.

  3. Enhancer activity of light-responsive regulatory elements in the untranslated leader regions of cyanobacterial psbA genes.

    PubMed Central

    Li, R; Golden, S S

    1993-01-01

    Three psbA genes encoding the D1 protein of the photosystem II reaction center are differentially expressed under different light intensities in the cyanobacterium Synechococcus sp. strain PCC 7942. Two of the three psbA genes, psbAII and psbAIII, are induced rapidly when light intensity is increased from 125 x 10(-6) mol.m-2.s-1 to 750 x 10(-6) mol.m-2.s-1. A recombinational cloning vector that carries a transcriptional lacZ reporter gene was used to characterize the controlling elements responsible for light induction. At least three distinct cis elements are present in the regulatory regions of pbsAII and psbAIII: basal promoters, comparable to Escherichia coli sigma 70 promoters in position and sequence, confer constitutive expression of the genes under both low and high light intensities; negative elements upstream of the promoters down-regulate the expression of the corresponding gene; and sequences downstream of the promoters that correspond to the untranslated leader regions of the mRNAs (+1 to +41 in psbAII and +1 to +39 in psbAIII) are responsible for increased expression under high light. When these light-responsive elements were combined with an E. coli promoter (conII) in different positions and orientations, the expression of the lacZ gene was induced 4- to 11-fold. The induction of gene expression under high light by these enhancers was position independent but orientation dependent. When the elements were combined with the conII promoter in the correct orientation, they also conferred a small but reproducible level of light-responsive expression on this E. coli promoter. Images Fig. 1 Fig. 3 Fig. 4 PMID:8265608

  4. A Finite Element Method for Free-Surface Flows of Incompressible Fluids in Three Dimensions, Part II: Dynamic Wetting Lines

    SciTech Connect

    Baer, T.A.; Cairncross, R.A.; Rao, R.R.; Sackinger, P.A.; Schunk, P.R.

    1999-01-29

    To date, few researchers have solved three-dimensional free-surface problems with dynamic wetting lines. This paper extends the free-surface finite element method described in a companion paper [Cairncross, R.A., P.R. Schunk, T.A. Baer, P.A. Sackinger, R.R. Rao, "A finite element method for free surface flows of incompressible fluid in three dimensions, Part I: Boundary-Fitted mesh motion.", to be published (1998)] to handle dynamic wetting. A generalization of the technique used in two dimensional modeling to circumvent double-valued velocities at the wetting line, the so-called kinematic paradox, is presented for a wetting line in three dimensions. This approach requires the fluid velocity normal to the contact line to be zero, the fluid velocity tangent to the contact line to be equal to the tangential component of web velocity, and the fluid velocity into the web to be zero. In addition, slip is allowed in a narrow strip along the substrate surface near the dynamic contact line. For realistic wetting-line motion, a contact angle which varies with wetting speed is required because contact lines in three dimensions typically advance or recede a different rates depending upon location and/or have both advancing and receding portions. The theory is applied to capillary rise of static fluid in a corner, the initial motion of a Newtonian droplet down an inclined plane, and extrusion of a Newtonian fluid from a nozzle onto a moving substrate. The extrusion results are compared to experimental visualization. Subject Categories

  5. Tuning cellular responses to BMP-2 with material surfaces

    PubMed Central

    Picart, Catherine; Cavalcanti-Adam, Elisabetta Ada

    2016-01-01

    Bone morphogenetic protein 2 (BMP-2) has been known for decades as a strong osteoinductive factor and for clinical applications is combined solely with collagen as carrier material. The growing concerns regarding side effects and the importance of BMP-2 in several developmental and physiological processes have raised the need to improve the design of materials by controlling BMP-2 presentation. Inspired by the natural cell environment, new material surfaces have been engineered and tailored to provide both physical and chemical cues that regulate BMP-2 activity. Here we describe surfaces designed to present BMP-2 to cells in a spatially and temporally controlled manner. This is achieved by trapping BMP-2 using physicochemical interactions, either covalently grafted or combined with other extracellular matrix components. In the near future, we anticipate that material science and biology will integrate and further develop tools for in vitro studies and potentially bring some of them toward in vivo applications. PMID:26704296

  6. Tuning cellular responses to BMP-2 with material surfaces.

    PubMed

    Migliorini, Elisa; Valat, Anne; Picart, Catherine; Cavalcanti-Adam, Elisabetta Ada

    2016-02-01

    Bone morphogenetic protein 2 (BMP-2) has been known for decades as a strong osteoinductive factor and for clinical applications is combined solely with collagen as carrier material. The growing concerns regarding side effects and the importance of BMP-2 in several developmental and physiological processes have raised the need to improve the design of materials by controlling BMP-2 presentation. Inspired by the natural cell environment, new material surfaces have been engineered and tailored to provide both physical and chemical cues that regulate BMP-2 activity. Here we describe surfaces designed to present BMP-2 to cells in a spatially and temporally controlled manner. This is achieved by trapping BMP-2 using physicochemical interactions, either covalently grafted or combined with other extracellular matrix components. In the near future, we anticipate that material science and biology will integrate and further develop tools for in vitro studies and potentially bring some of them toward in vivo applications.

  7. Cooling responses of finger in contact with an aluminum surface.

    PubMed

    Chen, F; Nilsson, H; Holmér, I

    1994-03-01

    Skin temperature (T sk) changes and subjective sensations of bare fingers touching a cold aluminum surface were determined in 25 subjects (12 female and 13 male). An 11-cm aluminum cube was placed in a mini-chamber, where chamber air and an aluminum cube were simultaneously cooled to -14, -5, and -1 degrees C, respectively. Subjects inserted their right hands into the chamber and pressed on the cube surface with three fingers with a force of 9.81 N (1 Kp). Exposure lasted until finger-skin temperature reached 0 degree C or was voluntarily ended by the subject. Regression equations with two exponential components were used to describe the relationship between T sk and exposure time. The short time constant (< 1 second) for the first part of the cooling curve is assumed to represent primarily thermocouple dynamics. The long time constant (> 20 seconds) for the second part of the cooling curve is interpreted as representing the rate of heat transfer from the tissues of the finger itself. Gender and cube-surface temperature had no significant effect on any of the time constants. Thermal sensation and pain sensation lacked a good correlation with the contact and T sk and T sk change.

  8. Identifying and separating magnetic and electric microwave responses of chiral elements

    NASA Astrophysics Data System (ADS)

    Kazantsev, Yu. N.; Kraftmakher, G. A.; Mal'tsev, V. P.

    2016-03-01

    We propose a technique for identifying the type of resonance excitation by ac magnetic or electric fields in conducting chiral elements by reflection of electromagnetic waves in the standing- and travelingwave modes. The technique was tested experimentally in the microwave range and confirmed numerically. We demonstrate the possibility of broadband matching of composite radar absorbing materials with the use of a lattice of resonance elements excited by magnetic field of the wave rather instead of the traditional quarter- wavelength effects.

  9. A novel four-legged loaded element thick-screen frequency selective surface with a stable performance

    NASA Astrophysics Data System (ADS)

    Tang, Guang-Ming; Miao, Jun-Gang; Dong, Jin-Ming

    2012-12-01

    A thick-screen frequency selective surface (FSS) has not only a broad bandwidth but also the advantages of overcoming the multilayer FSS shortcoming of complex structure and low transmittance of centre frequency due to the cascade of FSSs, and this means it could potentially be applied in a stealth curved streamlined radome. However, there is an unsteadiness of centre frequency in a wide range of incident angles and another unsteadiness of polarization in a big incident angle. In order to solve these problems, in this paper we provide a novel four-legged loaded element thick-screen FSS. The structure is analysed and simulated using the mode matching method and moment method. The centre frequency, the transmittance of centre frequency, and bandwidth of the structure are investigated when some parameters including the polarization at a big incident angle and the incident angles of TE & TM waves are changed. The novel four-legged loaded element thick-screen FSS has better transmission properties with a better steadiness of polarization and incident angle independence. The novel structure of the four-legged loaded element thick-screen FSS provides a valuable reference for their application in a stealth curved streamlined radome.

  10. Dynamic and thermal response finite element models of multi-body space structural configurations

    NASA Technical Reports Server (NTRS)

    Edighoffer, Harold H.

    1987-01-01

    Presented is structural dynamics modeling of two multibody space structural configurations. The first configuration is a generic space station model of a cylindrical habitation module, two solar array panels, radiator panel, and central connecting tube. The second is a 15-m hoop-column antenna. Discussed is the special joint elimination sequence used for these large finite element models, so that eigenvalues could be extracted. The generic space station model aided test configuration design and analysis/test data correlation. The model consisted of six finite element models, one of each substructure and one of all substructures as a system. Static analysis and tests at the substructure level fine-tuned the finite element models. The 15-m hoop-column antenna is a truss column and structural ring interconnected with tension stabilizing cables. To the cables, pretensioned mesh membrane elements were attached to form four parabolic shaped antennae, one per quadrant. Imposing thermal preloads in the cables and mesh elements produced pretension in the finite element model. Thermal preload variation in the 96 control cables was adjusted to maintain antenna shape within the required tolerance and to give pointing accuracy.

  11. Glucocorticoid activation of chromogranin A gene expression. Identification and characterization of a novel glucocorticoid response element.

    PubMed Central

    Rozansky, D J; Wu, H; Tang, K; Parmer, R J; O'Connor, D T

    1994-01-01

    Glucocorticoids regulate catecholamine biosynthesis and storage at several sites. Chromogranin A, an abundant protein complexed with catecholamines in secretory vesicles of chromaffin cells and sympathetic axons, is also augmented by glucocorticoids. This study reports isolation of the rat chromogranin A promoter to elucidate transcriptional regulation of chromogranin A biosynthesis by glucocorticoids in neuroendocrine cells. Endogenous chromogranin A gene expression was activated up to 3.5-fold in chromaffin cells by glucocorticoid, in time-dependent fashion. Inhibition of new protein synthesis by cycloheximide did not alter the rise in chromogranin A mRNA, suggesting that glucocorticoids directly activate the chromogranin A promoter; nuclear runoff assays confirmed a 3.3-fold increased rate of initiation of new chromogranin A transcripts after glucocorticoid. Transfected rat chromogranin A promoter/luciferase reporter constructs were activated 2.6-3.1-fold by glucocorticoid, and selective agonist/antagonist studies determined that dexamethasone effects were mediated by glucocorticoid receptors. Both rat and mouse chromogranin A promoter/luciferase reporter constructs were activated by glucocorticoid. A series of promoter deletions narrowed the region of glucocorticoid action to a 93-bp section of the promoter, from position -526 to -619 bp upstream of the cap site. A 15-bp sequence ([-583 bp] 5'-ACATGAGTGTGTCCT-3' [-597 bp]) within this region showed partial homology to a glucocorticoid response element (GRE; half-site in italics) consensus sequence, and several lines of experimental evidence confirmed its function as a GRE: (a) site-directed mutation of this GRE prevented glucocorticoid activation of a chromogranin A promoter/reporter; (b) transfer of this GRE to a heterologous (thymidine kinase) promoter/reporter conferred activation by glucocorticoid, in copy number-dependent and orientation-independent fashion; and (c) electrophoretic gel mobility shifts

  12. Mobility of major and trace elements in a coupled groundwater-surface water system: Merced River, CA

    NASA Astrophysics Data System (ADS)

    Wildman, R. A.; Domagalski, J. L.; Hering, J. G.

    2004-12-01

    Trace element transport in coupled surface water/groundwater systems is controlled not only by advective flow, but also by redox reactions that affect the partitioning of various elements between mobile and immobile phases. These processes have been examined in the context of a field project conducted by the U.S. Geological Survey (USGS) as part of the National Water-Quality Assessment (NAWQA) program. The Merced River flows out of Yosemite National Park and the Sierra Nevada foothills and into California's Central Valley, where it joins the San Joaquin River. Our field site is approximately twenty river kilometers from the confluence with the San Joaquin River. This deep alluvial plain has minimal topography. Agricultural development characterizes the land surrounding this reach of river; consequently, the hydrology is heavily influenced by irrigation. Riverbed groundwater samples were collected from ten wells aligned in two transects across the river located approximately 100 m apart. The wells were sampled from depths of 0.5 m, 1 m, and 3 m below the sediment-water interface. Groundwater flowpath samples were taken from wells positioned on a path perpendicular to the river and located 100 m, 500 m, and 1000 m from the river. The saturated groundwater system exists from 7 to 40 m below the surface and is confined below by a clay layer. Each well location samples from 3-5 depths in this surface aquifer. Samples were collected in December 2003, March-April, June-July, and October 2004. This served to provide an evenly-spaced sampling frequency over the course of a year, and also to allow observation of trends coinciding with the onset of winter, the spring runoff, and early and late summer irrigation. An initial survey of the elements in the riverbed samples was conducted using Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). Elements for further study were selected based on variability in this survey, either with respect to depth or location, as well as to

  13. Ectomycorrhizal influence on particle size, surface structure, mineral crystallinity, functional groups, and elemental composition of soil colloids from different soil origins.

    PubMed

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O-H stretching and bending, C-H stretching, C=O stretching, etc.) by 3-26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40-300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12-35% decreases in most functional groups, 15-55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C:O, C:N, and C:Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  14. Small Loosening of Bolt-nut Fastener Due to Micro Bearing-Surface Slip: A Finite Element Method Study

    NASA Astrophysics Data System (ADS)

    Izumi, Satoshi; Kimura, Masatake; Sakai, Shinsuke

    Bolt-nut fasteners are widely used in mechanical structures due to the systems' ease of disassembly for maintenance and their relatively low cost. However, vibration-induced loosening has remained problematic. In this paper, we investigated the mechanisms of the loosening process due to micro bearing-surface slip within the framework of the three-dimensional finite element method (FEM). The results show close agreement with Kasei's experimental results. It is found that the early-stage nut rotation observed experimentally originates from simultaneous bolt-nut rotation induced by the tightening torsion of the bolt and does not correspond to loosening rotation. Therefore, loosening rotation should be defined by the relative rotation angle of the nut with respect to the bolt. It is also found that small loosening is initiated when the vibration force reaches about 50 to 60% of the critical loading necessary for bearing-surface slip. Attention should be paid to the contact state of both bearing and thread surfaces when considering the loosening of bolt-nut tightening systems. Contact states can be classified into three types: complete slip involving no sticking region, micro slip involving no constant-sticking region over a vibration cycle, and localized slip involving a constant-sticking region over a vibration cycle. It is also found that loosening rotation can proceed when either micro slip or complete slip occurs at both the thread and bearing contact surfaces.

  15. The relationship of surface roughness and cell response of chemical surface modification of titanium

    PubMed Central

    Zareidoost, Amir; Ghaseme, Behrooz

    2012-01-01

    Implant surface topography influences osteoblastic proliferation, differentiation and extracellular matrix protein expressions. Previous researches proved that chemical surface modification of titanium implants could be used to improve Bone-to-implant contact. In this study, the surface topography, chemistry and biocompatibility of polished titanium surfaces treated with mixed solution of three acids containing HCl, HF and H3PO4 with different etched conditions for example concentration, time and addition of calcium chloride were studied. Osteoblast cells (MG-63) were cultured on different groups of titanium surfaces. In order to investigate titanium surfaces, SEM, AFM and EDS analyses were carried out. The results showed that surfaces treated with HCl–HF–H3PO4 had higher roughness, lower cytotoxicity level and better biocompatibility than controls. Moreover, addition of calcium chloride into mixed solution of three acids containing HCl, HF and H3PO4 is an important, predominant and new technique for obtaining biofunction in metals for biomedical use including dentistry. PMID:22460230

  16. Effects of Residual Elements Arsenic, Antimony, and Tin on Surface Hot Shortness

    NASA Astrophysics Data System (ADS)

    Yin, Lan; Sridhar, Seetharaman

    2011-10-01

    Scrap-based electric arc furnace (EAF) steelmaking is limited by a surface cracking problem in the recycled steel products, which is known as surface hot shortness. This problem originates from the excessive amount of copper (Cu) in the steel scrap, which enriches during the oxidation of iron (Fe) and consequently melts and penetrates into the austenite grain boundaries. In this article, the effects of arsenic (As), antimony (Sb), and tin (Sn) on surface hot shortness were investigated. A series of Fe-0.3 wt pct Cu- x wt pct (As, Sb, or Sn) alloys with x content ranging from 0.06 to 0.10 wt pct was oxidized in air at 1423 K (1150 °C) for 60, 300, and 600 seconds inside the chamber of a thermogravimety analyzer (TGA) where heat is supplied through infrared radiation. Scanning electron microscopy (SEM) investigations show that (1) the presence of Sb and Sn results in severe grain boundary cracking, whereas the presence of As does not, (2) open cracks with Fe oxides were found beneath the oxide/metal interface in the Sb and Sn alloys, and (3) the oxide/metal interfaces for all As, Sb, and Sn alloys are planar. Penetration experiments of pure Cu and Cu-30 wt pct Sn liquid were also conducted in the chamber of a hot-stage confocal laser scanning microscopy (CLSM) in nonoxidizing atmosphere: (1) on the Fe-35 wt pct manganese (Mn) alloys to study the correlation between cracking and grain boundary characters, and (2) on the pure Fe substrates to exclude the bulk segregation effects of Sn on grain boundary cracking. It was found that grain boundary cracking rarely took place on low-energy grain boundaries. The results also suggest that the bulk segregation of Sn in the substrate is not necessary to promote significant grain boundary cracking, and as long as the liquid phase contains Sn, it will be highly embrittling.

  17. Ion microprobe analysis of bone surface elements: Effects of 1,25(OH)2D3

    SciTech Connect

    Bushinsky, D.A.; Chabala, J.M.; Levi-Setti, R. )

    1989-12-01

    When neonatal mouse calvariae are incubated with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) there is net calcium efflux from the bone into the medium. The effect of this enhanced cell-mediated Ca efflux on the relative concentrations of mineral 23Na, 39K, and 40Ca has not previously been studied. We used an imaging scanning ion microprobe, utilizing secondary ion mass spectrometry, to compare the relative ion concentrations of Na, K, and Ca on the surface, subsurface, and cross-section of cultured bone incubated in the presence of 1,25(OH)2D3 with the ion concentrations in similar regions of bone incubated in unaltered control medium. Changes in mineral ion concentration were correlated with net fluxes of Na, K, and Ca relative to bone. Calvariae incubated in control medium (24 h at pH approximately 7.40) have abundant surface Na and K relative to Ca (Na/Ca, 85 and K/Ca, 68), whereas the subsurface has less Na/Ca (21) and K/Ca (23), and on cross section the ratios of both Na/Ca (2.0) and K/Ca (1.9) decrease further. After incubation with 10(-8) M 1,25(OH)2D3, there is a significant increase in bone surface Na/Ca (154) and K/Ca (141) without a change in these ratios on the subsurface and a small fall in both ratios on cross section. The linear relationship between Na/Ca and K/Ca across the three regions of bone observed in control calvariae did not change with 1,25(OH)2D3 treatment. As determined by flux measurements there is a net efflux of Ca but not Na or K from bone.

  18. Photoelectron emission analysis of surface elements of the International Sun Earth Explorer

    NASA Technical Reports Server (NTRS)

    Spencer, W. T.

    1975-01-01

    The photoemission was measured of engineering materials (aluminum; copper, plain; copper, abraded; copper-beryllium; magnesium; silver; In2O3 on silica; reflective coating on silica; teflon; kapton; and Pyre ML) associated with the International Sun Earth Explorer (ISEE) Satellite. The procedures used are described, including the experimental equipment; results of the program, the conclusions reached, and areas for further work are presented. Data regarding the measured yield of the 11 materials whose surface emission was determined is included in the form of plots of photoelectric yield versus incident light wavelength.

  19. Optimization of ingredients for noodle preparation using response surface methodology.

    PubMed

    Vijayakumar, T Poongodi; Boopathy, P

    2014-08-01

    In the present investigation, the composite flour combinations using whole wheat flour (X1), tapioca flour (X2) and defatted soy flour (X3) for the noodle preparation were made through central composite rotatable design (CCRD). The analyzed responses were bulk density (BD), proximate composition, water uptake ratio (WUR), cooking volume expansion (VE), water absorption capacity (WAC), swelling capacity (SC), gruel solid loss (GSL), and sensory characteristics. A second order quadratic polynomial equation was fitted to the data of all responses for prediction. The maximum protein content of 16 g% was achieved by the combination of 75.54 g of whole wheat flour, 10 g of tapioca flour and 19.78 g of defatted soy flour. Since the inclusion of defatted soy flour >10 g resulted negative influence on good quality determining responses, the Chinese salted noodles of excellent quality with maximum WAC, WUR, VE, SC, protein, carbohydrate, ash and minimum GSL, BD, fat, moisture could be made from ratio of combination of three independent variables at 77.33 g (X1): 22.19 g (X2): 8.92 g (X3) respectively. The cost of production per kg of noodles with optimum level of ingredient was Rs.75.50/-. PMID:25114340

  20. Atranorin and lecanoric acid antagonize TCDD-induced xenobiotic response element-driven activity, but not xenobiotic response element-independent activity.

    PubMed

    Nakashima, Ken-Ichi; Tanabe, Hiroki; Fujii-Kuriyama, Yoshiaki; Hayashi, Hidetoshi; Inoue, Makoto

    2016-07-01

    Lichens are symbiotic organisms that consist of fungi and photosynthetic symbionts (algae and/or cyanobacteria). Previous studies of their constituents suggested lichens produce many kinds of aromatic secondary metabolites, such as depsides, quinones, and dibenzofurans. In this study, we evaluated the aryl hydrocarbon receptor (AhR) antagonistic activity of 17 lichen substances and demonstrated that atranorin (1) and lecanoric acid (2), isolated from Parmotrema tinctorum Hale, showed an inhibitory effect on luciferase activity increased by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), using an XRE-driven pX4TK-Luc reporter gene assay. In addition, CYP1A1 mRNA and protein levels increased by TCDD were also suppressed by 1 and 2. Conversely, neither 1 nor 2 antagonized the suppressive effect of TCDD on interleukin (IL)-1β-induced acute-phase response (APR) gene expression. Thus, we concluded that 1 and 2 were selective AhR modulators that antagonize XRE-dependent activity, but not XRE-independent activity. However, 1 has different characteristics to 2 in that 1 alone showed a suppressive effect on IL-1β-induced APR gene expression in a similar fashion to TCDD. PMID:26979434

  1. Response of nickel surface to pulsed fusion plasma radiations

    SciTech Connect

    Niranjan, Ram Rout, R. K. Srivastava, R. Gupta, Satish C.; Chakravarthy, Y.; Patel, N. N.; Alex, P.

    2014-04-24

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  2. Response of nickel surface to pulsed fusion plasma radiations

    NASA Astrophysics Data System (ADS)

    Niranjan, Ram; Rout, R. K.; Srivastava, R.; Chakravarthy, Y.; Patel, N. N.; Alex, P.; Gupta, Satish C.

    2014-04-01

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  3. SANTOS - a two-dimensional finite element program for the quasistatic, large deformation, inelastic response of solids

    SciTech Connect

    Stone, C.M.

    1997-07-01

    SANTOS is a finite element program designed to compute the quasistatic, large deformation, inelastic response of two-dimensional planar or axisymmetric solids. The code is derived from the transient dynamic code PRONTO 2D. The solution strategy used to compute the equilibrium states is based on a self-adaptive dynamic relaxation solution scheme, which is based on explicit central difference pseudo-time integration and artificial mass proportional damping. The element used in SANTOS is a uniform strain 4-node quadrilateral element with an hourglass control scheme to control the spurious deformation modes. Finite strain constitutive models for many common engineering materials are included. A robust master-slave contact algorithm for modeling sliding contact is implemented. An interface for coupling to an external code is also provided. 43 refs., 22 figs.

  4. First-principles study on the effect of alloying elements on the elastic deformation response in β-titanium alloys

    SciTech Connect

    Gouda, Mohammed K. Gepreel, Mohamed A. H.; Nakamura, Koichi

    2015-06-07

    Theoretical deformation response of hypothetical β-titanium alloys was investigated using first-principles calculation technique under periodic boundary conditions. Simulation was carried out on hypothetical 54-atom supercell of Ti–X (X = Cr, Mn, Fe, Zr, Nb, Mo, Al, and Sn) binary alloys. The results showed that the strength of Ti increases by alloying, except for Cr. The most effective alloying elements are Nb, Zr, and Mo in the current simulation. The mechanism of bond breaking was revealed by studying the local structure around the alloying element atom with respect to volume change. Moreover, the effect of alloying elements on bulk modulus and admissible strain was investigated. It was found that Zr, Nb, and Mo have a significant effect to enhance the admissible strain of Ti without change in bulk modulus.

  5. How reliable are environmental data on 'orphan' elements? The case of bismuth concentrations in surface waters.

    PubMed

    Filella, Montserrat

    2010-01-01

    Like all elements of the periodic table, bismuth is ubiquitously distributed throughout the environment as a result of natural processes and human activities. It is present as Bi(III) in environmental, biological and geochemical samples. Although bismuth and its compounds are considered to be non-toxic to humans, its increasing use as a replacement for lead has highlighted how little is known about its environmental and ecotoxicological behaviour. In this first critical review paper on the existing information on bismuth occurrence in natural waters, 125 papers on fresh and marine waters have been collated. Although the initial objective of this study was to establish the range of the typical concentrations of total dissolved bismuth in natural waters, this proved impossible to achieve due to the wide, and hitherto unexplained, dispersion of published data. Since analytical limitations might be one of the reasons underlying value dispersion, new analytical methods published since 2000--intended to be applied to natural waters--have also been reviewed. Disappointingly, the detection limits of the bulk of them are well above those required; they are thus of limited usefulness. Analysis of the existing information on bismuth in secondary references (i.e., books, review chapters) and on its chemical speciation in seawater revealed that the uncritical reproduction of old data is a widespread practice.

  6. A finite-element model for simulating hydraulic interchange of surface and ground water

    USGS Publications Warehouse

    Glover, K.C.

    1988-01-01

    A model was developed to be useful for predicting changes in streamflow as a result of groundwater pumping. The stream aquifer model is especially useful for simulating streams that flow intermittently owing to leakage to the aquifer or diversion for irrigation or streams that become perched owing to declining hydraulic head in the aquifer. The model couples the equation of two-dimensional groundwater flow with the kinematic equations of one-dimensional open-channel flow. Darcy 's law for vertical flow through a semipermeable streambed is used to couple the groundwater flow and streamflow equations. The equations of flow are approximated numerically by the finite-element method. A listing of the Fortran program that solves the equations of flow , and a description of data-input formats are given in the report. The program can simulate a variety of hydrologic characteristics including perched streams, streamflow diversions , springs, recharge from irrigated acreage, and evapotranspiration from the water table and phreatophytes. Time-dependent boundary conditions can be simulated. The program can be modified easily to simulate unconfined aquifers and aquifers with variable directions of anisotropy. (USGS)

  7. Finite Element Analysis of Three Methods for Microwave Heating of Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin; Kaukler, William

    2012-01-01

    In-Situ Resource Utilization will be Ground Breaking technology for sustained exploration of space. Volatiles are present in planetary regolith, but water by far has the most potential for effective utilization. The presence of water at the lunar poles and Mars opens the possibility of using the hydrogen for propellant on missions beyond Earth orbit. Likewise, the oxygen could be used for in-space propulsion for lunar ascent/descent and for space tugs from low lunar orbit to low Earth orbit. Water is also an effective radiation shielding material as well as a valuable expendable (water and oxygen) required for habitation in space. Because of the strong function of water vapor pressure with temperature, heating regolith effectively liberates water vapor by sublimation. Microwave energy will penetrate soil and heat from within, much more efficiently than heating from the surface with radiant heat. This is especially true under vacuum conditions since the heat transfer rate is very low. The depth of microwave penetration is a strong function of the microwave frequency and to a lesser extent on regolith dielectric properties. New methods for delivery of microwaves i