Science.gov

Sample records for element response surfaces

  1. 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.

  2. Response Surface Analysis of Elemental Composition and Energy Properties of Corn Stover During Torrefaction

    SciTech Connect

    Jaya Shankar Tumuluru; Richard D. Boardman; Christopher T. Wright

    2012-02-01

    This research studied the effects of torrefaction temperature (250-250 C) and time (30-120 minutes) on elemental composition and energy properties changes in corn stover. Torrefied material was analyzed for moisture content, moisture-free carbon (%), hydrogen (%), nitrogen (%), sulfur (%), and higher heating value (MJ/kg). Results at 350 C and 120 minutes indicated a steep decrease in moisture content to a final value of about 1.48% - a reduction of about 69%. With respect to carbon content, the increase was about 23%, while hydrogen and sulfur content decreased by about 46.82% and 66.6%, respectively. The hydrogen-to-carbon ratio decreased as torrefaction temperature and time increased, with the lowest value of 0.6 observed at 350 C and 120 minutes. Higher heating value measured at 350 C and 60 minutes increased by about 22% and the maximum degree of carbonization observed was about 1.21. Further, the regression models developed for chemical composition in terms of torrefaction temperature and time adequately described the process with coefficient of determination values (R2) in the range of 0.92-0.99 for the elemental composition and energy properties studied. Response surface plots indicated that increasing both torrefaction temperature and time resulted in decreased moisture content, hydrogen content, and the hydrogen to-carbon ratio, and increased carbon content and higher heating value. This effect was more significant at torrefaction temperatures and times >280 C and >30 minutes.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Manned Mars mission surface transportation elements

    NASA Technical Reports Server (NTRS)

    Mcdaniel, S. Gregg; Mulqueen, Jack

    1986-01-01

    The necessity and advantage of surface transportation was well demonstrated by the Apollo 15, 16, and 17 missions. Baseline surface transportation elements for further studies are Lunar Rover, Elastic Loop Mobility System, Mobile Laboratory, Airplane, and Rocket Powered Flying Vehicles. These types of surface transportation are discussed. Starting points for further in-depth studies are identified.

  11. 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

  12. Nuclear responses in INTOR plasma stabilization elements

    NASA Astrophysics Data System (ADS)

    Gohar, Y.; Mattas, R. F.; Yang, S.; Wiffen, F. W.

    Nuclear responses in the plasma stabilization elements were studied in a parametric fashion as a part of the transient electromagnetics critical issue C of ETR/INTOR activity. The main responses are neutron fluence and radiation dose in the insulator material, induced resistively and atomic displacement in the conductor material, nuclear heating and life analysis for the elements. Copper and aluminum conductors with either MgAl2O4 or MgO insulating material were investigated. Radiation damage and life analysis for these elements were also discussed.

  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. Finite element solutions of free surface flows

    NASA Technical Reports Server (NTRS)

    Zarda, P. R.; Marcus, M. S.

    1977-01-01

    A procedure is presented for using NASTRAN to determine the flow field about arbitrarily shaped bodies in the presence of a free surface. The fundamental unknown of the problem is the velocity potential which must satisfy Laplace's equation in the fluid region. Boundary conditions on the free surface may involve second order derivatives in space and time. In cases involving infinite domains either a tractable radiation condition is applied at a truncated boundary or a series expansion is used and matched to the local finite elements. Solutions are presented for harmonic, transient, and steady state problems and compared to either exact solutions or other numerical solutions.

  15. Natural Elements Method for Free Surface Flow

    NASA Astrophysics Data System (ADS)

    Darbani, M.; Ouahsine, A.; Villon, P.

    2009-09-01

    The Natural Element Method (NEM) is used to simulate a 2D shallow water flow in presence of free surface and a varying bathymetry. This meshless method used a fully Lagrangian formulation and natural neighbors, which remain a very striking problem related the boundary conditions. The method was succefully used to simulate dam-break flows by solving the fully nonlinear Shallow Water Equations (SWE) and by using an implicit scheme under a transient flow and the Coriolis effect.

  16. Cross-linking of surface Ig receptors on murine B lymphocytes stimulates the expression of nuclear tetradecanoyl phorbol acetate-response element-binding proteins

    SciTech Connect

    Chiles, T.C.; Liu, J.L.; Rothstein, T.L. )

    1991-03-15

    Cross-linking of sIg on primary B lymphocytes leads to increased nuclear DNA-binding activity specific for the tetradecanoyl phorbol acetate-response element (TRE), as judged by gel mobility shift assays. Stimulation of B cells to enter S phase of the cell cycle by treatment with the combination of phorbol ester plus calcium ionophore also stimulated nuclear TRE-binding activity within 2 h, with maximal expression at 4 h; however, phorbol ester and calcium ionophore were not as effective in stimulating binding activity when examined separately. Stimulated nuclear expression of TRE-binding activity appears to require protein synthesis. Fos- and Jun/AP-1-related proteins participate directly in the identified nucleoprotein complex, as shown by the ability of c-fos- and c-jun-specific antisera to either alter or completely abolish electrophoretic migration of the complex in native gels. Further, UV photo-cross-linking studies identified two major TRE-binding protein species, whose sizes correspond to TRE-binding proteins derived from HeLa cell nuclear extracts. The results suggest that in primary B cells nuclear TRE-binding activity represents a downstream signaling event that occurs subsequent to changes in protein kinase C activity and intracellular Ca2+ but that can be triggered physiologically through sIg.

  17. 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 ...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Factors affecting response of surface waters to acidic deposition

    SciTech Connect

    Turner, R.S.; Johnson, D.W.; Elwood, J.W.; Van Winkle, W.; Clapp, R.B.; Reuss, J.O.

    1986-04-01

    Knowledge of watershed hydrology and of the biogeochemical reactions and elemental pools and fluxes occurring in watersheds can be used to classify the response of watersheds and surface waters to acidic deposition. A conceptual mosel is presented for classifying watersheds into those for which (1) surface water chemistry will change rapidly with deposition quality (direct response) (2) surface water chemistry will change only slowly over time (delayed response), and (3) surface water chemistry will not change significantly, even with continued acidic deposition (capacity-protected). Techniques and data available for classification of all watersheds in a region into these categories are discussed.

  5. Surface recognition elements of membrane protein oligomerization.

    PubMed

    Rath, Arianna; Deber, Charles M

    2008-02-15

    Although certain membrane proteins are functional as monomeric polypeptides, others must assemble into oligomers to carry out their biological roles. High-resolution membrane protein structures provide a valuable resource for examining the sequence features that facilitate-or preclude-assembly of membrane protein monomers into multimeric structures. Here we have utilized a data set of 28 high-resolution alpha-helical membrane protein structures comprising 32 nonredundant polypeptides to address this issue. The lipid-exposed surfaces of membrane proteins that have reached their fully assembled and functional biological units have been compared with those of the individual subunits that build quaternary structures. Though the overall amino acid composition of each set of surfaces is similar, a key distinction-the distribution of small-xxx-small motifs-delineates subunits from membrane proteins that have reached a functioning oligomeric state. Quaternary structure formation may therefore be dictated by small-xxx-small motifs that are not satisfied by intrachain contacts. PMID:17729275

  6. 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.

  7. 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

  8. 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.

  9. Computation of Schenberg response function by using finite element modelling

    NASA Astrophysics Data System (ADS)

    Frajuca, C.; Bortoli, F. S.; Magalhaes, N. S.

    2016-05-01

    Schenberg is a detector of gravitational waves resonant mass type, with a central frequency of operation of 3200 Hz. Transducers located on the surface of the resonating sphere, according to a distribution half-dodecahedron, are used to monitor a strain amplitude. The development of mechanical impedance matchers that act by increasing the coupling of the transducers with the sphere is a major challenge because of the high frequency and small in size. The objective of this work is to study the Schenberg response function obtained by finite element modeling (FEM). Finnaly, the result is compared with the result of the simplified model for mass spring type system modeling verifying if that is suitable for the determination of sensitivity detector, as the conclusion the both modeling give the same results.

  10. 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. PMID:15563547

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Finite element simulation of temperature dependent free surface flows

    NASA Technical Reports Server (NTRS)

    Engelman, M. S.; Sani, R. L.

    1985-01-01

    The method of Engelman and Sani (1984) for a finite-element simulation of incompressible surface flows with a free and/or moving fluid interface, such as encountered in crystal growth and coating and polymer technology, is extended to temperature-dependent flows, including the effect of temperature-dependent surface tension. The basic algorithm of Saito and Scriven (1981) and Ruschak (1980) has been generalized and implemented in a robust and versatile finite-element code that can be employed with relative ease for the simulation of free-surface problems in complex geometries. As a result, the costly dependence on the Newton-Raphson algorithm has been eliminated by replacing it with a quasi-Newton iterative method, which nearly retains the superior convergence properties of the Newton-Raphson method.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. Asymptotic behavior of curvature of surface elements in isotropic turbulence

    NASA Technical Reports Server (NTRS)

    Girimaji, S. S.

    1991-01-01

    The asymptotic behavior of the curvature of material elements in turbulence is investigated using Lagrangian velocity-gradient time series obtained from direct numerical simulations of isotropic turbulence. Several material-element ensembles of different initial curvatures and shapes are studied. It is found that, at long times, the (first five) moments of the logarithm of characteristic curvature and shape factor asymptote to values that are independent of the initial curvature or shape. This evidence strongly suggests that the asymptotic pdf's of the curvature and shape of material elements are stationary and independent of initial conditions. Irrespective of initial curvature or shape, the asymptotic shape of a material surface is cylindrical with a high probability.

  3. 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.

  4. 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.

  5. Finite element simulation of impact response of wire mesh screens

    NASA Astrophysics Data System (ADS)

    Wang, Caizheng; Shankar, Krishna; Fien, Alan

    2015-09-01

    In this paper, the response of wire mesh screens to low velocity impact with blunt objects is investigated using finite element (FE) simulation. The woven wire mesh is modelled with homogeneous shell elements with equivalent smeared mechanical properties. The mechanical behaviour of the woven wire mesh was determined experimentally with tensile tests on steel wire mesh coupons to generate the data for the smeared shell material used in the FE. The effects of impacts with a low mass (4 kg) and a large mass (40 kg) providing the same impact energy are studied. The joint between the wire mesh screen and the aluminium frame surrounding it is modelled using contact elements with friction between the corresponding elements. Damage to the screen of different types compromising its structural integrity, such as mesh separation and pulling out from the surrounding frame is modelled. The FE simulation is validated with results of impact tests conducted on woven steel wire screen meshes.

  6. 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

  7. Surface hardening of cutting elements agricultural machinery vibro arc plasma

    NASA Astrophysics Data System (ADS)

    Sharifullin, S. N.; Adigamov, N. R.; Adigamov, N. N.; Solovev, R. Y.; Arakcheeva, K. S.

    2016-01-01

    At present, the state technical policy aimed at the modernization of worn equipment, including agriculture, based on the use of high-performance technology called nanotechnology. By upgrading worn-out equipment meant restoring it with the achievement of the above parameters passport. The existing traditional technologies are not suitable for the repair of worn-out equipment modernization. This is especially true of imported equipment. Out here alone - is the use of high-performance technologies. In this paper, we consider the use of vibro arc plasma for surface hardening of cutting elements of agricultural machinery.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Tribological thin films on steel rolling element bearing surfaces

    NASA Astrophysics Data System (ADS)

    Evans, Ryan David

    Tribological thin films are of interest to designers and end-users of friction management and load transmission components such as steel rolling element bearings. This study sought to reveal new information about the properties and formation of such films, spanning the scope of their technical evolution from natural oxide films, to antiwear films from lubricant additives, and finally engineered nanocomposite metal carbide/amorphous hydrocarbon (MC/a-C:H) films. Transmission electron microscopy (TEM) was performed on the near-surface material (depth < 500 nm) of tapered roller bearing inner rings (cones) that were tested at two levels of boundary-lubricated conditions in mineral oil with and without sulfur- and phosphorus-containing gear oil additives. Site-specific thinning of cross-section cone surface sections for TEM analyses was conducted using the focused ion beam milling technique. Two types of oxide surface films were characterized for the cones tested in mineral oil only, each one corresponding to a different lubrication severity. Continuous and adherent antiwear films were found on the cone surfaces tested with lubricant additives, and their composition depended on the lubrication conditions. A sharp interface separated the antiwear film and base steel. Various TEM analytical techniques were used to study the segregation of elements throughout the film volume. The properties of nanocomposite tantalum carbide/amorphous hydrocarbon (TaC/a-C:H) thin films depend sensitively on reactive magnetron sputtering deposition process conditions. TaC/a-C:H film growth was studied as a function of three deposition parameters in designed experiments: acetylene flow rate, applied d.c. bias voltage, and substrate carousel rotation rate. Empirical models were developed for the following film characteristics to identify process-property trend relationships: Ta/C atomic ratio, hydrogen content, film thickness. TaC crystallite size, Raman spectrum, compressive stress, hardness

  14. 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

  15. Dendritic Cell Responses to Surface Properties of Clinical Titanium Surfaces

    PubMed Central

    Kou, Peng Meng; Schwartz, Zvi; Boyan, Barbara D.

    2010-01-01

    Dendritic cells (DCs) play pivotal roles in responding to foreign entities during an innate immune response and initiating effective adaptive immunity as well as maintaining immune tolerance. The sensitivity of DCs to foreign stimuli also makes them useful cells to assess the inflammatory response to biomaterials. Elucidating the material property-DC phenotype relationships using a well-defined biomaterial system is expected to provide criteria for immuno-modulatory biomaterial design. Clinical titanium (Ti) substrates, including pretreatment (PT), sand-blasted and acid-etched (SLA), and modified SLA (modSLA), with different roughness and surface energy were used to treat DCs and resulted in differential DC responses. PT and SLA induced a mature DC (mDC) phenotype, while modSLA promoted a non-inflammatory environment by supporting an immature DC (iDC) phenotype based on surface marker expression, cytokine production profiles and cell morphology. Principal component analysis (PCA) confirmed these experimental results, and it also indicated that the non-stimulating property of modSLA covaried with certain surface properties, such as high surface hydrophilicity, % oxygen and % Ti of the substrates. In addition to the previous research that demonstrated the superior osteogenic property of modSLA compared to PT and SLA, the result reported herein indicates that modSLA may further benefit implant osteo-integration by reducing local inflammation and its associated osteoclastogenesis. PMID:20977948

  16. 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.

  17. 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.

  18. Ocean response to surface heat anomalies

    NASA Technical Reports Server (NTRS)

    Jiang, Xingjian; Fung, Inez

    1994-01-01

    An ocean general circulation model (OGCM) is used to study the response of ocean heat and mass transport to positive and negative heat flux anomalies at the ocean surface. As expected, tropical and low-latitude mixed layers respond rapidly (e-folding time about 50-70 years) to external forcing, while the response of the high-latitude mixed layer, especially the Southern Ocean and northern North Atlantic, is very slow (e-folding time greater than 300 yr). The overall response is faster for negative than positive heat flux anomaly at the surface. The meridional heat transport changes by 15% in the first 50 yr in the southern high latitudes. Surprisingly, for the next 400-500 yr the change is very small. The analysis shows that the meridional mass transport intensifies in response to a negative surface heat flux anomaly but weakens in response to a positive heat flux anomaly. For example, at model year 100 the North Atlantic Deep Water (NADW) is reduced from about 18 Sv to about 10 Sv for the positive heat flux experiment but increased to about 26 Sv for the negative heat flux experiment.

  19. 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

  20. Electrically Responsive Surfaces: Experimental and Theoretical Investigations.

    PubMed

    Cantini, Eleonora; Wang, Xingyong; Koelsch, Patrick; Preece, Jon A; Ma, Jing; Mendes, Paula M

    2016-06-21

    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 orientation of

  1. 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.

  2. Functional Response of NiTi Elements for Smart Micro-actuation Applications

    NASA Astrophysics Data System (ADS)

    Biffi, C. A.; Nespoli, A.; Previtali, B.; Villa, E.; Tuissi, A.

    2014-07-01

    Shape memory alloys (SMAs) can be considered a good candidate for actuation applications in the current micro-technology field. In the micro-scale, the temporal response of the SMA actuators can be improved, because of faster cooling during the austenite-martensite transformation. One of the most investigated geometries for this purpose has been the snake-like arrangement, which allows high strokes with considerable forces to be obtained. In this work, SMA elements for micro-actuators were patterned by laser machining in a snake-like shape. Subsequent surface chemical etching was adopted to improve the functional properties of the micro-elements. Calorimetric analysis and thermo-mechanical response of 90 μm thick SMA elements were reported for the evaluation of their functional performances. Moreover, the effect of post-thermal treatment and grain orientation were also evaluated on the final performances.

  3. 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.

  4. Hierarchical construction of stratigraphic elements in surface-based reservoir models

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Xu, S.; Mukerji, T.

    2013-12-01

    We present a surface-based simulation algorithm connecting stratigraphic hierarchy with surface-based reservoir models through statistical metrics. Geostatistical simulation algorithms provide tools for modeling spatial complexity and the resulting uncertainties for energy resource assessments. As a new family within a wide array of stochastic geological models, surface-based models and rule-based algorithms effectively represent stratigraphic responses to geological events in both time and space by assigning depositional and erosional surfaces with predefined geometries and rules. Recent advances in surface-based modeling focus on simulating morphological evolution of deep-water depositional systems and constraining models to available well and seismic data. However, especially in deep-water plays, scarce well data can only bring information about local stratal features rather than relatively general information such as hierarchy or organization, when these features are below seismic resolution. Without such information, surface-based models lack geological realism and may not be reliable even when conditioned to data. Our proposed surface-based simulation algorithm links stratigraphic hierarchy with surface-based reservoir modeling through spatial statistical tools. Ripley's K-function is used to quantitatively describe the stratigraphic distribution patterns of channel deposits. We also use the compensation index metric for quantifying the strength of compensational stacking in stratigraphic elements. These two metrics help us to extract information about sedimentary hierarchy and element organization from a set of experimental strata, and bridge physical tank experiments with numerical models. We utilize these two geostatistical metrics in conjunction with a surface-based simulation algorithm to 1) integrate clustering and compensational stacking patterns of channel deposits into reservoir modeling 2) make numerical models represent a stratigraphic hierarchical

  5. Finite element cochlear models and their steady state response

    NASA Astrophysics Data System (ADS)

    Kagawa, Y.; Yamabuchi, T.; Watanabe, N.; Mizoguchi, T.

    1987-12-01

    Numerical cochlear models are constructed by means of a finite element approach and their frequency and spatial responses are calculated. The cochlea is modelled as a coupled fluid-membrane system, for which both two- and three-dimensional models are considered. The fluid in the scala canals is assumed to be incompressible and the basilar membrane is assumed to be a locally reactive impedance wall or a lossy elastic membrane. With the three-dimensional models, the effects are examined of the spiral configuration of the cochlea, of the presence of the lamina and the ligament that narrows the coupling area between the two fluid canals (scala vestibuli and scala tympani), and of the extended reaction of the basilar membrane which cannot be included in case of the two-dimensional models. The conclusion is that these effects on the cochlear response and the inherent mechanism governing the cochlear behaviour are found to be rather secondary.

  6. Structural characteristic responses for finite element model updating of structures

    NASA Astrophysics Data System (ADS)

    Zhou, Linren; Wang, Lei; Ou, Jinping

    2014-04-01

    The field measurements of structures are very important to the structural finite element (FE) model updating because the errors and uncertainties of a FE model are corrected directly through closing the discrepancies between the analytical responses from FE model and the measurements from field testing of a structure. Usually, the accurate and reliable field measurements are very limited. Therefore, it is very important to make full use of the limited and valuable field measurements in structural model updating to achieve a best result with the lowest cost. In this paper, structural FE model updating is investigated in the point of view of solving a mathematical problem, and different amount and category of structural dynamic responses and static responses are considered as constraints to explore their effects on the updated results of different degree and types of structural damages. The numerical studies are carried out on a space truss. Accounting for the numerical results, some inherent phenomena and connections taking account of the updating parameters, output responses and the updated results are revealed and discussed. Some useful and practicable suggestions about using the field measurements for FE model updating are provided to achieve efficient and reliable results.

  7. Osteoblast response to biomimetically altered titanium surfaces.

    PubMed

    Nebe, J Barbara; Müller, Lenka; Lüthen, Frank; Ewald, Andrea; Bergemann, Claudia; Conforto, Egle; Müller, Frank A

    2008-11-01

    Bioinert titanium (Ti) materials are generally encapsulated by fibrous tissue after implantation into the living body. To improve the bone-bonding ability of Ti implants, we activated commercially pure titanium (cpTi) by a simple chemical pre-treatment in HCl and NaOH. Subsequently, we exposed the treated samples to simulated body fluid (SBF) for 2 (TiCT) and 14 days (TiHCA), respectively, to mimic the early stages of bone bonding and to investigate the in vitro response of osteoblasts on thus altered biomimetic surfaces. Sample surfaces were characterized by scanning electron microscopy, energy-dispersive X-ray analysis, cross-sectional transmission electron microscopy analyses, Fourier transform infrared and Raman spectroscopy. It was shown that the efflorescence consisting of sodium titanate that is present on pre-treated cpTi surfaces transformed to calcium titanate after 2 days in SBF. After 14 days in SBF a homogeneous biomimetic apatite layer precipitated. Human osteoblasts (MG-63) revealed a well spread morphology on both functionalized Ti surfaces. On TiCT, the gene expression of the differentiation proteins alkaline phosphatase (ALP) and bone sialo protein was increased after 2 days. On both TiCT and TiHCA, the collagen I and ALP expression on the protein level was enhanced at 7 and 14 days. The TiCT and the TiHCA surfaces reveal the tendency to increase the differentiated cell function of MG-63 osteoblasts. Thus, chemical pre-treatment of titanium seems to be a promising method to generate osteoconductive surfaces. PMID:18595788

  8. 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

  9. 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

  10. Human osteoblast response to PTFE surfaces.

    PubMed

    Walsh, W R; Olmedo, M; Kim, H D; Zou, L; Weiss, A P

    1994-01-01

    Recently, expanded polytetrafluoroethylene (ePTFE, Gortex) vascular grafts have been rolled and used for interpositional arthroplasties of the carpus in the wrist. Little data, however, are available on the response of human osteoblasts to ePTFE. In-vitro cell culture is a useful method to determine initial cell-biomaterial interactions. The present study explores the morphological and mitogenic response of human bone cells cultured on vascular grade ePTFE grafts. The present findings suggest that neither the inner nor the outer surface of ePTFE, in its present form, support osteoblast growth. PTFE may be a suitable material to act as a space filler for carpal bone interpositional arthroplasties. PMID:10150168

  11. Bioavailability of trace elements in surface sediments from Kongsfjorden, Svalbard.

    PubMed

    Grotti, Marco; Soggia, Francesco; Ianni, Carmela; Magi, Emanuele; Udisti, Roberto

    2013-12-15

    The bioavailability of trace elements in marine sediments from Kongsfjorden (Svalbard Islands, Norwegian Arctic) was assessed and discussed. Total concentrations of several elements were determined in two granulometric fractions and their bioavailability evaluated by both applying a sequential-selective extraction procedure and using a biomimetic approach based on proteolytic enzymes. Total concentration values and solid speciation patterns indicated overall that the anthropogenic impact of trace elements in the investigated area is negligible, although a minor enrichment with respect to crustal values was found for As, Cd, Cr, Ni, and V. Enrichment of trace elements in the <63-μm fraction compared to the coarser one was evident for As, Cd, Cr, and Ni. The evaluation of the bioavailable fractions showed that a large part of the total content of trace elements cannot enter the aquatic food chain and emphasised the risk of overestimating the environmental impact of heavy metals if the assessment is only based on total concentrations. PMID:24210011

  12. 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.

  13. Surface expression of GABAA receptors is transcriptionally controlled by the interplay of cAMP-response element-binding protein and its binding partner inducible cAMP early repressor.

    PubMed

    Hu, Yinghui; Lund, Ingrid V; Gravielle, Maria C; Farb, David H; Brooks-Kayal, Amy R; Russek, Shelley J

    2008-04-01

    The regulated expression of type A gamma-aminobutyric acid (GABA) receptor (GABA(A)R) subunit genes plays a critical role in neuronal maturation and synaptogenesis. It is also associated with a variety of neurological diseases. Changes in GABA(A) receptor alpha1 subunit gene (GABRA1) expression have been reported in animal models of epilepsy, alcohol abuse, withdrawal, and stress. Understanding the genetic mechanism behind such changes in alpha subunit expression will lead to a better understanding of the role that signal transduction plays in control over GABA(A)R function and brings with it the promise of providing new therapeutic tools for the prevention or cure of a variety of neurological disorders. Here we show that activation of protein kinase C increases alpha1 subunit levels via phosphorylation of CREB (pCREB) that is bound to the GABRA1 promoter (GABRA1p). In contrast, activation of protein kinase A decreases levels of alpha1 even in the presence of pCREB. Decrease of alpha1 is dependent upon the inducible cAMP early repressor (ICER) as directly demonstrated by ICER-induced down-regulation of endogenous alpha1-containing GABA(A)Rs at the cell surface of cortical neurons. Taken together with the fact that there are less alpha1gamma2-containing GABA(A)Rs in neurons after protein kinase A stimulation and that activation of endogenous dopamine receptors down-regulates alpha1 subunit mRNA levels subsequent to induction of ICER, our studies identify a transcriptional mechanism for regulating the cell surface expression of alpha1-containing GABA(A)Rs that is dependent upon the formation of CREB heterodimers. PMID:18180303

  14. 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.

  15. 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.

  16. 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.

  17. Removal of ghost images by using tilted element optical systems with polynomial surfaces for aberration compensation

    NASA Astrophysics Data System (ADS)

    Rogers, Jeremy D.; Tkaczyk, Tomasz S.; Descour, Michael R.; Kärkkäinen, Ari H.; Richards-Kortum, Rebecca

    2006-02-01

    A novel solution to problematic ghost images is implemented by using tilted lens elements with polynomial surfaces. Tilting the lens surfaces sends reflections out of the imaging path. The nonrotationally symmetric polynomial surfaces correct aberrations caused by tilts. The complex lens surfaces are fabricated by using gray-scale lithographic patterning of hybrid solgel glass.

  18. Removal of ghost images by using tilted element optical systems with polynomial surfaces for aberration compensation.

    PubMed

    Rogers, Jeremy D; Tkaczyk, Tomasz S; Descour, Michael R; Kärkkäinen, Ari H O; Richards-Kortum, Rebecca

    2006-02-15

    A novel solution to problematic ghost images is implemented by using tilted lens elements with polynomial surfaces. Tilting the lens surfaces sends reflections out of the imaging path. The nonrotationally symmetric polynomial surfaces correct aberrations caused by tilts. The complex lens surfaces are fabricated by using gray-scale lithographic patterning of hybrid solgel glass. PMID:16496901

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Effects of CO/CO2/NO on elemental lead adsorption on carbonaceous surfaces.

    PubMed

    Gao, Zhengyang; Yang, Weijie

    2016-07-01

    The adsorption processes of elemental lead on carbonaceous surfaces which adsorbed CO/CO2/NO flue gases were investigated to understand the effects of CO/CO2/NO on elemental lead adsorption on carbonaceous surfaces with density functional theory. All calculations including optimizations, energies, and frequencies were conducted at B3PW91 density functional theory level, utilizing SDD basis set for lead and 6-31G(d) Pople basis set for other atoms. The results indicate that CO, CO2, and NO can promote the adsorption of elemental lead on the carbonaceous surface, but probably compete for adsorption sites with elemental lead. The promotion effects on adsorption can be attributed to active sites on the carbonaceous surface rather than flue gas adsorption on the carbonaceous surface. In addition, the adsorption order of three kinds of flue gas on the carbonaceous surface is CO2 > NO > CO > Pb on average. Furthermore, the enhancement order of three kinds of flue gas on the elemental lead adsorption on carbonaceous surfaces is CO-CS > CO2-CS > NO-CS > CS in general. In particular, atomic charge and adsorption energy have good linear relationship in the process of elemental lead adsorption. Graphical Abstract Competitive adsorption between flue gas and elemental lead on carbonaceous surfaces. PMID:27342251

  5. 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.

  6. 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.

  7. Evaluation of flyash surface phenomena and the application of surface analysis technology. Summary report: Phase I. [44 elements; 86 references

    SciTech Connect

    Smith, R.D.

    1981-06-01

    The factors governing the formation of flyash surfaces during and following coal combustion are reviewed. The competing chemical and physical processes during the evolution of inorganic material in coal during combustion into flyash are described with respect to various surface segregation processes. Two mechanisms leading to surface enrichment are volatilization-condensation processes and diffusion processes within individual flyash particles. The experimental evidence for each of these processes is reviewed. It is shown that the volatilization-condensation process is the major factor leading to trace element enrichment in smaller flyash particles. Evidence also exists from surface analyses of flyash and representative mineral matter that diffusion processes may lead to surface enrichment of elements not volatilized or cause transport of surface-condensed elements into the flyash matrix. The semiquantitative determination of the relative importance of these two processes can be determined by comparison of concentration versus particle size profiles with surface-depth profiles obtained using surface analysis techniques. A brief description of organic transformations on flyash surfaces is also presented. The various surface analytical techniques are reviewed and the relatively new technique of Static-Secondary Ion Mass Spectroscopy is suggested as having significant advantages in studies of surfaces and diffusion processes in model systems. Several recommendations are made for research relevant to flyash formation and processes occurring on flyash surfaces.

  8. 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

  9. Identification of response surface models using genetic programming

    NASA Astrophysics Data System (ADS)

    Lew, T. L.; Spencer, A. B.; Scarpa, F.; Worden, K.; Rutherford, A.; Hemez, F.

    2006-11-01

    There is a move in modern research in Structural Dynamics towards analysing the inherent uncertainty in a given problem. This may be quantifying or fusing uncertainty models, or can be propagation of uncertainty through a system or calculation. If the system of interest is represented by, e.g. a large Finite Element (FE) model the large number of computations involved can rule out many approaches due to the expense of carrying out many runs. One way of circumnavigating this problem is to replace the true system by an approximate surrogate/replacement model, which is fast-running compared to the original. In traditional approaches using response surfaces a simple least-squares multinomial model is often adopted. The objective of this paper is to extend the class of possible models considerably by carrying out a general symbolic regression using a Genetic Programming approach. The approach is demonstrated on both univariate and multivariate problems with both computational and experimental data.

  10. Structured Extended Finite Element Methods of Solids Defined by Implicit Surfaces

    SciTech Connect

    Belytschko, T; Mish, K; Moes, N; Parimi, C

    2002-11-17

    A paradigm is developed for generating structured finite element models from solid models by means of implicit surface definitions. The implicit surfaces are defined by radial basis functions. Internal features, such as material interfaces, sliding interfaces and cracks are treated by enrichment techniques developed in the extended finite element method (X-FEM). Methods for integrating the weak form for such models are proposed. These methods simplify the generation of finite element models. Results presented for several examples show that the accuracy of this method is comparable to standard unstructured finite element methods.

  11. 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.

  12. An in Situ Technique for Elemental Analysis of Lunar Surfaces

    NASA Technical Reports Server (NTRS)

    Kane, K. Y.; Cremers, D. A.

    1992-01-01

    An in situ analytical technique that can remotely determine the elemental constituents of solids has been demonstrated. Laser-Induced Breakdown Spectroscopy (LIBS) is a form of atomic emission spectroscopy in which a powerful laser pulse is focused on a solid to generate a laser spark, or microplasma. Material in the plasma is vaporized, and the resulting atoms are excited to emit light. The light is spectrally resolved to identify the emitting species. LIBS is a simple technique that can be automated for inclusion aboard a remotely operated vehicle. Since only optical access to a sample is required, areas inaccessible to a rover can be analyzed remotely. A single laser spark both vaporizes and excites the sample so that near real-time analysis (a few minutes) is possible. This technique provides simultaneous multielement detection and has good sensitivity for many elements. LIBS also eliminates the need for sample retrieval and preparation preventing possible sample contamination. These qualities make the LIBS technique uniquely suited for use in the lunar environment.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Singh, Chandan; Saini, Jaswinder Singh

    2016-05-01

    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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Role of Oxygen as Surface-Active Element in Linear GTA Welding Process

    NASA Astrophysics Data System (ADS)

    Yadaiah, Nirsanametla; Bag, Swarup

    2013-11-01

    Although the surface-active elements such as oxygen and sulfur have an adverse effect on momentum transport in liquid metals during fusion welding, such elements can be used beneficially up to a certain limit to increase the weld penetration in the gas tungsten arc (GTA) welding process. The fluid flow pattern and consequently the weld penetration and width change due to a change in coefficient of surface tension from a negative value to a positive value. The present work is focused on the analysis of possible effects of surface-active elements to change the weld pool dimensions in linear GTA welding. A 3D finite element-based heat transfer and fluid flow model is developed to study the effect of surface-active elements on stainless steel plates. A velocity in the order of 180 mm/s due to surface tension force is estimated at an optimum concentration of surface-active elements. Further, the differential evolution-based global optimization algorithm is integrated with the numerical model to estimate uncertain model parameters such as arc efficiency, effective arc radius, and effective values of material properties at high temperatures. The effective values of thermal conductivity and viscosity are estimated to be enhanced nine and seven times, respectively, over corresponding room temperature values. An error analysis is also performed to find out the overall reliability of the computed results, and a maximum reliability of 0.94 is achieved.

  1. Optimum design criteria for a synchronous reluctance motor with concentrated winding using response surface methodology

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ho; Park, Seong-June; Jeon, Su-Jin

    2006-04-01

    This paper presents an optimization procedure using response surface methodology (RSM) to determine design parameters for reducing torque ripple. The RSM has been achieved to use the experimental design method in combination with finite element method and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables.

  2. Finite element analysis of fluid behavior under micro surface waves

    NASA Astrophysics Data System (ADS)

    Shi, Yanru; Gao, Weimin; Yu, Zhenxian; Kong, Lingxue; Hsu, Hung-Yao

    2006-01-01

    The wide utilisation of micro-systems has brought increasing attention into micro-fluidics in recent years. When the size and mass of a device are scaled down, forces which used to be ignored may become dominant in the performance of a micro system. This paper studies the behaviour of fluid responding to travelling sinusoidal waves imposed by a micro actuator. The thickness of the fluid between the wave surface and the substrate is 20 microns, and the wavelength is 50 microns. The model is developed and implemented in ANSYS. The nonlinearities of the flow exist in both X and Y directions. A stable thrust force can be generated by the moving waves. The direction of the thrust force is opposite to the direction of the travelling wave. The magnitude of the thrust force is related to fluid viscosity, wave amplitude, and wave frequency. As this force is highly predictable and controllable, it can be used to propel a micro device working in thin tubes filled with fluid. The principle could also be applied to non-Newtonian fluid, although the flow will be more complicate.

  3. Planetary gamma-ray spectroscopy. [for element distribution over planetary surfaces

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    1978-01-01

    The measured intensities of certain gamma rays of specific energies escaping from a planetary surface can be used to determine the abundances of a number of elements. The fluxes of the more intense gamma ray lines emitted from 32 elements have been calculated using current nuclear data and existing models for the source processes. The fluxes emitted from a surface of average lunar composition are reported for 292 gamma ray lines. Detection sensitivities for various elements are examined and applications of gamma ray spectroscopy for future orbiters to Mars and other solar system objects are discussed.

  4. 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

  5. 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.

  6. 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.

  7. A finite element surface impedance representation for steady-state problems

    NASA Technical Reports Server (NTRS)

    Kalinowski, A. J.

    1986-01-01

    A procedure for determining the scattered pressure field resulting from a monochromatic harmonic wave that is incident upon a layer energy absorbing structure is treated. The situation where the structure is modeled with finite elements and the surrounding acoustic medium (water or air) is represented with either acoustic finite elements, or some type of boundary integral formulation, is considered. Finite element modeling problems arise when the construction of the structure, at the fluid structure interface, are nonhomogeneous and in particular, when the inhomogeneities are small relative to the acoustic wave length. An approximate procedure is presented for replacing the detailed microscopic representation of the layered surface configuration with an equivalent simple surface impedance finite element, which is especially designed to work only at limited frequencies. An example problem is presented using NASTRAN. However, the procedure is general enough to adapt to practically any finite element code having a steady state option.

  8. Cis-element of the rice PDIL2-3 promoter is responsible for inducing the endoplasmic reticulum stress response.

    PubMed

    Takahashi, Hideyuki; Wang, Shuyi; Hayashi, Shimpei; Wakasa, Yuhya; Takaiwa, Fumio

    2014-05-01

    A protein disulfide isomerase (PDI) family oxidoreductase, PDIL2-3, is involved in endoplasmic reticulum (ER) stress responses in rice. We identified a critical cis-element required for induction of the ER stress response. The activation of PDIL2-3 in response to ER stress strongly depends on the IRE1-OsbZIP50 signaling pathway. PMID:24315532

  9. 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.

  10. Anomalous surface segregation behaviour of some 3d elements in ferromagnetic iron.

    PubMed

    Gupta, Michèle; Gupta, Raju P

    2013-10-16

    The segregation of Cr in Fe is known to be anomalous since the barrier for surface segregation of Cr is not determined by the topmost surface layer, as one would expect, but rather by the subsurface layer where the energy of segregation is much larger and endothermic. This has been attributed to a complex interaction involving the antiferromagnetism of Cr and the ferromagnetism of Fe. We report in this paper the results of our ab initio electronic structure calculations on the segregation behaviour of all the 3d elements on the (1 0 0) surface of ferromagnetic iron in the hope of better understanding this phenomenon. We find a similar behaviour for the segregation of the next antiferromagnetic 3d element Mn in Fe, where the subsurface layer is also found to block the segregation of Mn to the surface. On the other hand, ferromagnetic Co exhibits a normal segregation behaviour. The elements Sc, Cu and Ni do not form solid solutions with ferromagnetic iron. The early elements Ti and V are non-magnetic in their metallic states, but are strongly polarized by Fe, and develop magnetic moments which are aligned antiferromagnetically to those of Fe atoms. While the subsurface layer blocks the segregation of Ti to the surface, no blocking behaviour is found for the segregation of V. The segregation behaviour of all these elements is strongly correlated with the displacement of the solute atoms on the surface of Fe. The elements showing anomalous segregation behaviour are all displaced upwards on the surface, while those showing normal segregation are pulled inwards. These results indicate that the antiferromagnetism of the segregating element plays the key role in the anomalous segregation behaviour in Fe. PMID:24047767

  11. 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.

  12. Finite element model calibration using frequency responses with damping equalization

    NASA Astrophysics Data System (ADS)

    Abrahamsson, T. J. S.; Kammer, D. C.

    2015-10-01

    Model calibration is a cornerstone of the finite element verification and validation procedure, in which the credibility of the model is substantiated by positive comparison with test data. The calibration problem, in which the minimum deviation between finite element model data and experimental data is searched for, is normally characterized as being a large scale optimization problem with many model parameters to solve for and with deviation metrics that are nonlinear in these parameters. The calibrated parameters need to be found by iterative procedures, starting from initial estimates. Sometimes these procedures get trapped in local deviation function minima and do not converge to the globally optimal calibration solution that is searched for. The reason for such traps is often the multi-modality of the problem which causes eigenmode crossover problems in the iterative variation of parameter settings. This work presents a calibration formulation which gives a smooth deviation metric with a large radius of convergence to the global minimum. A damping equalization method is suggested to avoid the mode correlation and mode pairing problems that need to be solved in many other model updating procedures. By this method, the modal damping of a test data model and the finite element model is set to be the same fraction of critical modal damping. Mode pairing for mapping of experimentally found damping to the finite element model is thus not needed. The method is combined with model reduction for efficiency and employs the Levenberg-Marquardt minimizer with randomized starts to achieve the calibration solution. The performance of the calibration procedure, including a study of parameter bias and variance under noisy data conditions, is demonstrated by two numerical examples.

  13. 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.

  14. 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.

  15. Finite element modeling of the surface roughness of 5052 Al alloy subjected to a surface severe plastic deformation process

    SciTech Connect

    Dai, K.; Villegas, J.; Stone, Z.; Shaw, L. . E-mail: lshaw@mail.ims.uconn.edu

    2004-12-01

    The surface of 5052 Al alloy plates is severely plastically deformed via multiple impacts by high-velocity tungsten carbide/cobalt (Wc/Co) balls in a surface nanocrystallization and hardening (SNH) process. The surface roughness of 5052 Al alloy plates as a function of the impacting ball size and processing time has been evaluated via non-contact 3D profilometry. A three-dimensional finite element (FE) model has been developed to simulate the formation of peaks and valleys during the SNH process. The peak-to-valley distance predicted from the FEM matches the maximum PV value measured experimentally quite well, indicating that surface roughening of 5052 Al alloy plates during the SNH process using WC/Co balls is mainly dictated by the indentation process of the impacting balls. The implications of this surface roughening mechanism in the final surface roughness, processing time, related microstructure change, and property alteration are discussed.

  16. Mapping chemical elements on the surface of orthodontic appliance by SEM-EDX

    PubMed Central

    Mikulewicz, Marcin; Wołowiec, Paulina; Michalak, Izabela; Chojnacka, Katarzyna; Czopor, Wojciech; Berniczei-Royko, Adam; Vegh, Andras; Gedrange, Thomas

    2014-01-01

    Background During orthodontic treatment, the various elements that constitute the fixed appliance undergo different processes. As a result of a change of the surface, elution/coverage of metals on the surface can be observed in the process of corrosion/passivation. Material/Methods Scanning electron microscopy with an energy-dispersive X-ray analytical system (SEM-EDX) was used to analyze the composition of stainless steel elements of orthodontic fixed appliances (before and after orthodontic treatment), to obtain the composition of the surface of the elements. The analyzed elements were: brackets (Victory Series APC PLUS 022, 3M Unitek, Monrovia, CA, USA); wires (0.017×0.025, 3M Unitek, Monrovia, CA, USA); and bands (37+, 3M Unitek, Monrovia, CA, USA). Results The results showed a decrease of chromium and iron contribution to the surface, with increase of oxygen content in used vs. new elements of the appliance. Conclusions Our results confirm the formation of oxides (passivation layer) on the surface of stainless steel as a result of the presence of the orthodontic appliance in patients’ oral cavities. PMID:24857929

  17. 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

  18. 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. PMID:18503669

  19. Cooperative chemisorption of K and O elements on cleaved GaAs(110) surface

    NASA Astrophysics Data System (ADS)

    Ren, Bin; Miao, Zhuang; Hou, Zhi-Peng; Cheng, Hong-Chang; Shi, Feng; Jiao, Gang-Cheng; Bai, Xiao-Feng; Niu, Sen; Wang, Long; Fu, Ling-Yun

    2014-09-01

    Using the projected augmented wave potential by the density functional theory based upon gradual gradient approach method and the slab model, from the calculated surface, we identify the relaxed atoms sites of GaAs(110) surface, the electronic structure of elements K and O adsorpted on binding sites of ideal GaAs(110) surface have also been calculated, especially the total energy of the adsorption system. The comparison results of calculated total energy showed: for K and O elements at highest coverage of Θ=1ML on GaAs(110) surface, they were not formed to local domain of competitive chemical adsorption, while they were formed to a compound uniformity phase of cooperative chemical adsorption. Our calculated results providing theoretical basis and reference for the application of alkali oxidation adsorpted on GaAs surface to form a negative electron affinity photocathode.

  20. 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.

  1. 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…

  2. 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

  3. Design of responsive materials using topologically interlocked elements

    NASA Astrophysics Data System (ADS)

    Molotnikov, A.; Gerbrand, R.; Qi, Y.; Simon, G. P.; Estrin, Y.

    2015-02-01

    In this work we present a novel approach to designing responsive structures by segmentation of monolithic plates into an assembly of topologically interlocked building blocks. The particular example considered is an assembly of interlocking osteomorphic blocks. The results of this study demonstrate that the constraining force, which is required to hold the blocks together, can be viewed as a design parameter that governs the bending stiffness and the load bearing capacity of the segmented structure. In the case where the constraining forces are provided laterally using an external frame, the maximum load the assembly can sustain and its stiffness increase linearly with the magnitude of the lateral load applied. Furthermore, we show that the segmented plate with integrated shape memory wires employed as tensioning cables can act as a smart structure that changes its flexural stiffness and load bearing capacity in response to external stimuli, such as heat generated by the switching on and off an electric current.

  4. 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

  5. Enhancement of RIE: etched Diffractive Optical Elements surfaces by using Ion Beam Etching

    NASA Astrophysics Data System (ADS)

    Schmitt, J.; Bischoff, Ch.; Rädel, U.; Grau, M.; Wallrabe, U.; Völklein, F.

    2015-09-01

    Shaping of laser light intensities by using Diffractive Optical Elements allows the adaption of the incident light to its application. Fused silica is used where for example UV-light or high temperatures are mandatory. For high diffraction efficiency the quality of the etched surface areas is important. The investigation of different process parameters for Ion Beam and Reactive Ion Etching reveals that only Ion Beam Etching provides surfaces with optical quality. Measurements of the influence of the surface quality on the diffraction efficiencies prove that the surfaces generated by Reactive Ion Etching are not suitable. Due to the high selectivity of the process Reactive Ion Etching is nevertheless a reasonable choice for the fabrication of Diffractive Optical Elements. To improve the quality of the etched surfaces a post processing with Ion Beam Etching is developed. Simulations in MATLAB display that the angle dependent removal of the surface during the Ion Beam Etching causes a smoothing of the surface roughness. The positive influence of a post processing on the diffraction efficiency is outlined by measurements. The ion beam post processing leads to an increase of the etching depth. For the fabrication of high efficient Diffractive Optical Elements this has to be taken into account. The relation is investigated and transferred to the fabrication of four-level gratings. Diffraction efficiencies up to 78 % instead of the ideal 81 % underline the practicability of the developed post processing.

  6. 33 CFR Appendix C to Part 155 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Training Elements for Oil Spill.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General 1.1The... capabilities of the contracted oil spill removal organizations and the procedures to notify and activate...

  7. 33 CFR Appendix C to Part 155 - 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.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General 1.1The... capabilities of the contracted oil spill removal organizations and the procedures to notify and activate...

  8. 33 CFR Appendix C to Part 155 - Training Elements for Oil Spill Response Plans

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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 1.1The... capabilities of the contracted oil spill removal organizations and the procedures to notify and activate...

  9. 33 CFR Appendix C to Part 155 - 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.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General 1.1The... capabilities of the contracted oil spill removal organizations and the procedures to notify and activate...

  10. 33 CFR Appendix C to Part 155 - 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.... 155, App. C Appendix C to Part 155—Training Elements for Oil Spill Response Plans 1. General 1.1The... capabilities of the contracted oil spill removal organizations and the procedures to notify and activate...

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

    SciTech Connect

    Susan Elizabeth Lorge

    2007-12-01

    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 10{sup 7}-10{sup 10}atoms/cm{sup 2} 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 representation of the

  12. Reconstruction of Caribbean Sea Surface Temperatures Using the Skeletal Elemental Composition of the Coral Siderastrea Siderea

    NASA Astrophysics Data System (ADS)

    Fowell, S.; Foster, G. L.; Ries, J. B.; Castillo, K.; Stewart, J.

    2014-12-01

    Anthropogenic climate change has resulted in an increase in sea surface temperature (SST) of 0.1oC per decade from 1971-2010. Satellite data reveals that Southern Belize has experienced greater temperature increases of up to 0.9oC from 1982 to 2009. Recent investigations have demonstrated that this warming has had a negative impact on coral calcification [1,2]. Instrumental temperature records in this region prior to 2002 are sparse, and the coarse spatial resolution of the satellite temperature data from 1982 to 2009 present problems when comparing changes in SST to rates of coral calcification. This makes it necessary to reconstruct past ocean temperatures indirectly to more accurately assess the impact of SST changes on coral calcification. The trace element composition of coral skeletons has been widely used in palaeothermometery, based on the assumption that the incorporation of trace elements such as Li, Mg and Sr (expressed as a ratio to Ca) is temperature dependent. In this study, we investigate the elemental composition of two samples sets (i) Siderastrea siderea coral samples cultured at controlled temperatures and pH, and (ii) annual and monthly resolved field samples of S. siderea measured across three major reef zones. To explore the optimum method for SST reconstruction in this species, the widely used Sr/Ca temperature proxy is compared with the more recently described Li/Mg proxy [3,4]. We demonstrate that Li/Mg appears to be the most reliable temperature proxy, with a well-defined correlation with temperature such that it is able to provide more precise temperature reconstructions than the traditional Sr/Ca approach. The results of this study pave the way to using Li/Mg in S. siderea as a reliable palaeothermometer to further our understanding of the response of Caribbean reef systems to climate change. [1] Castillo et al., 2011. PLoS One, 6(2): e14615. [2] Castillo et al., 2012. Nature Climate Change, 2: 756-760 2. [3] Hathorne et al., 2013

  13. 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

  14. Elemental mass spectroscopy of remote surfaces from laser-induced plasmas

    NASA Technical Reports Server (NTRS)

    Situ, W.; DeYoung, R. J.

    1994-01-01

    The elemental mass analysis of laser-produced ions from Al, Cu, Ge, Ag, and a lunar simulant target when irradiated by a 400-mJ, 8-ns, Nd: YAG laser at 1 x 10(exp 9) W/cm(exp 2), is reported. Ions traveled down a 11.1-m evacuated tube to an ion-trap 1-m time-of-flight (TOF) mass spectrometer where an elemental mass spectrum was recorded. The amount of target material removed per laser pulse and the ionization fraction were measured. The ion spatial distribution was measured at 11.1-m distance and found to be near a fourth-power cosine distribution. These results indicate the ability to mass analyze a surface over a distance of many kilometers for lunar and asteroid surface elemental mass analysis by a remote satellite or lunar rover.

  15. Finite Element Simulation of Sheet Metal Forming Process Using Local Interpolation for Tool Surfaces

    SciTech Connect

    Hama, Takayuki; Takuda, Hirohiko; Takamura, Masato; Makinouchi, Akitake; Teodosiu, Cristian

    2005-08-05

    Treatment of contact between a sheet and tools is one of the most difficult problems to deal with in finite-element simulations of sheet forming processes. In order to obtain more accurate tool models without increasing the number of elements, this paper describes a new formulation for contact problems using interpolation proposed by Nagata for tool surfaces. A contact search algorithm between sheet nodes and the interpolated tool surfaces was developed and was introduced into the static-explicit elastoplastic finite-element method code STAMP3D. Simulations of a square cup deep drawing process with a very coarsely discretized punch model were carried out. The simulated results showed that the proposed algorithm gave the proper drawn shape, demonstrating the validity of the proposed algorithm.

  16. New experimental method of visualizing the electric field due to surface charges on circuit elements

    NASA Astrophysics Data System (ADS)

    Jacobs, Rebecca; de Salazar, Alex; Nassar, Antonio

    2010-12-01

    Although static surface charges on circuit elements are of enormous interest, recent papers and textbooks have only discussed the problem theoretically using analytical or numerical approaches. The only well-known experimental method to visualize the structure of electric fields around circuit elements was reported by Jefimenko almost half a century ago. In our paper, we report on a simple method to visualize the electric field produced by static surface charges on current-carrying circuit elements. Our method uses a mixture of PTFE (Teflon) sealant and mineral oil, a copper wire placed in the mixture's container, and two 6 kV power supplies. We believe that our new method can be used directly in the classroom.

  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 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...

  19. Transport of trace elements in runoff from unamended and pond-ash amended feedlot surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of pond ash (fly ash that has been placed in evaporative ponds for storage and subsequently dewatered) for feedlot surfaces provides a drier environment for livestock and furnishes economic benefits. However, pond ash is known to have high concentrations of trace elements and the runoff wate...

  20. 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.

  1. Lunar surface heat flow mapping from radioactive elements measured by Lunar Prospector

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Li, Xiongyao; Li, Qingxia; Lang, Liang; Zheng, Yongchun

    2014-06-01

    An accurate estimate of global surface heat flow is important because it provides strong constraints on interior thermal model and understanding of the thermal state and geologic evolution of the Moon. In this paper, a distribution map of lunar surface heat flow is derived from calibrated Lunar Prospector gamma-ray spectrometer data (K, U and Th abundances). It shows that surface heat flow varies regionally from about 10.6 mW/m2 to 66.1 mW/m2, which is in the same order of magnitude as previous results. In the calculation, lunar surface heat flow includes the heat flow from the non-uniform distribution of radioactive elements K, U and Th and that from secular cooling of the Moon. The calculation of heat flow from radioactive elements is based on the assumption that the radioactive decay of K, U and Th on the Moon is the same as that on the Earth. The heat flow from secular cooling of the Moon is assumed to be equal to the global average radioactive heat flow. Firstly we construct a relationship between radioactive elements K, U and Th and lunar surface heat flow. The key parameter of the characteristic length scale in the relationship is determined by measured surface heat flow and Th abundances at Apollo 15 and 17 landing sites. Then the distribution of lunar surface heat flow is derived by combining other parameters such as lunar crustal thickness measured by Clementine and lunar crustal density. In addition, correlation analysis of the three radioactive elements is carried out due to the higher resolution of Th abundance and for ease of calculation.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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. PMID:23967003

  11. 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

  12. 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

  13. 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.

  14. 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. PMID:23595995

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    PubMed

    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

  2. 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

  3. Response Ant Colony Optimization of end milling surface roughness.

    PubMed

    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

  4. 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

  5. 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

  6. 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.

  7. 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

  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. 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

  10. 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.

  11. 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

  12. Modulation of Immune Response Using Engineered Nanoparticle Surfaces.

    PubMed

    Moyano, Daniel F; Liu, Yuanchang; Peer, Dan; Rotello, Vincent M

    2016-01-01

    Nanoparticles (NPs) coated with a monolayer of ligands can be recognized by different components of the immune system, opening new doors for the modulation of immunological responses. By the use of different physical or chemical properties at the NP surface (such as charge, functional groups, and ligand density), NPs can be designed to have distinct cellular uptake, cytokine secretion, and immunogenicity, factors that influence the distribution and clearance of these particles. Understanding these immunological responses is critical for the development of new NP-based carriers for the delivery of therapeutic molecules, and as such several studies have been performed to understand the relationships between immune responses and NP surface functionality. In this review, we will discuss recent reports of these structure-activity relationships, and explore how these motifs can be controlled to elicit therapeutically useful immune responses. PMID:26618755

  13. Study of bacterial adhesion on biomimetic temperature responsive glycopolymer surfaces.

    PubMed

    Wang, Yinan; Kotsuchibashi, Yohei; Liu, Yang; Narain, Ravin

    2015-01-28

    Pseudomonas aeruginosa is an opportunistic pathogen responsible for diseases such as bacteremia, chronic lung infection, and acute ulcerative keratitis. P. aeruginosa induced diseases can be fatal as the exotoxins and endotoxins released by the bacterium continue to damage host tissues even after the administration of antibiotics. As bacterial adhesion on cell surfaces is the first step in bacterial based pathogen infections, the control of bacteria-cell interactions is a worthwhile research target. In this work, thermally responsive poly(N-isopropylacrylamide) [P(NIPAAm)] based biomimetic surfaces were developed to study the two major bacterial infection mechanisms, which is believed to be mediated by hydrophobic or lectin-carbohydrate interactions, using quartz crystal microbalance with dissipation. Although, a greater number of P. aeruginosa adhered to the NIPAAm homopolymer modified surfaces at temperatures higher than the lower critical solution temperature (LCST), the bacterium-substratum bond stiffness was stronger between P. aeruginosa and a galactose based P(NIPAAm) surface. The high bacterial adhesion bond stiffness observed on the galactose based thermally responsive surface at 37 °C might suggest that both hydrophobic and lectin-carbohydrate interactions contribute to bacterial adhesion on cell surfaces. Our investigation also suggests that the lectin-carbohydrate interaction play a significant role in bacterial infections. PMID:25548940

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. Examination of the surface coating removed from K-East Basin fuel elements

    SciTech Connect

    Abrefah, J.; Marschman, S.C.; Jenson, E.D.

    1998-05-01

    This report provides the results of studies conducted on coatings discovered on the surfaces of some N-Reactor spent nuclear fuel (SNF) elements stored at the Hanford K-East Basin. These elements had been removed from the canisters and visually examined in-basin during FY 1996 as part of a series of characterization tests. The characterization tests are being performed to support the Integrated Process Strategy developed to package, dry, transport, and store the SNF in an interim storage facility on the Hanford site. Samples of coating materials were removed from K-East canister elements 2350E and 2540E, which had been sent, along with nine other elements, to the Postirradiation Testing Laboratory (327 Building) for further characterization following the in-basin examinations. These coating samples were evaluated by Pacific Northwest National Laboratory using various analytical methods. This report is part of the overall studies to determine the drying behavior of corrosion products associated with the K-Basin fuel elements. Altogether, five samples of coating materials were analyzed. These analyses suggest that hydration of the coating materials could be an additional source of moisture in the Multi-Canister Overpacks being used to contain the fuel for storage.

  19. 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

  20. 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

  1. Evolutionary Plasticity of Polycomb/Trithorax Response Elements in Drosophila Species

    PubMed Central

    Altmutter, Christina; Paro, Renato; Rehmsmeier, Marc

    2008-01-01

    cis-Regulatory DNA elements contain multiple binding sites for activators and repressors of transcription. Among these elements are enhancers, which establish gene expression states, and Polycomb/Trithorax response elements (PREs), which take over from enhancers and maintain transcription states of several hundred developmentally important genes. PREs are essential to the correct identities of both stem cells and differentiated cells. Evolutionary differences in cis-regulatory elements are a rich source of phenotypic diversity, and functional binding sites within regulatory elements turn over rapidly in evolution. However, more radical evolutionary changes that go beyond motif turnover have been difficult to assess. We used a combination of genome-wide bioinformatic prediction and experimental validation at specific loci, to evaluate PRE evolution across four Drosophila species. Our results show that PRE evolution is extraordinarily dynamic. First, we show that the numbers of PREs differ dramatically between species. Second, we demonstrate that functional binding sites within PREs at conserved positions turn over rapidly in evolution, as has been observed for enhancer elements. Finally, although it is theoretically possible that new elements can arise out of nonfunctional sequence, evidence that they do so is lacking. We show here that functional PREs are found at nonorthologous sites in conserved gene loci. By demonstrating that PRE evolution is not limited to the adaptation of preexisting elements, these findings document a novel dimension of cis-regulatory evolution. PMID:18959483

  2. 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

  3. A consensus insulin response element is activated by an Ets-related transcription factor.

    PubMed

    Jacob, K K; Ouyang, L; Stanley, F M

    1995-11-17

    Insulin increases expression of somatostatin-chloramphenicol acetyltransferase (CAT) constructs 10-fold and thymidine kinase-CAT constructs 5-fold in GH4 cells. These responses are similar to our previously reported data on insulin-increased prolactin-CAT expression. They are also observed in HeLa cells and are thus not cell type specific. The evidence suggests that the insulin responsiveness of these genes is mediated by an Ets-related transcription factor. First, linker-scanning mutations and/or deletions of the prolactin, somatostatin, and thymidine kinase promoters suggest that their insulin responsiveness is mediated by the sequence CGGA. This sequence is identical with the response element of the Ets-related transcription factors. Second, CGGA-containing sequences placed at -88 in the delta MTV-CAT reporter plasmid conferred insulin responsiveness to the mammary tumor virus promoter. Third, expression of the DNA-binding domain of c-Ets-2, which acts by blocking effects mediated by Ets-related transcription factors, inhibits the response of these promoters to insulin. Finally, the Ets-related proteins Sap and Elk-1 bind to the prolactin, somatostatin, and thymidine kinase insulin-response elements. An Ets-like element was found in all insulin-sensitive promoters examined and may serve a similar function in those promoters. PMID:7499246

  4. 3D Spectral Element Method Simulations Of The Seismic Response of Caracas (Venezuela) Basin

    NASA Astrophysics Data System (ADS)

    Delavaud, E.; Vilotte, J.; Festa, G.; Cupillard, P.

    2007-12-01

    We present here 3D numerical simulations of the response of the Caracas (Venezuela) valley up to 5 Hz for different scenarios of plane wave excitation based on the regional seismicity. Attention is focused on the effects of the 3D basin geometry and of the adjacent regional topography. The simulations are performed using Spectral Element method (SEM) together with an unstructured hexahedral mesh discretization and perfectly matched layers (PML). These simulations show 3D amplification phenomena associated with complex wave reflexion, diffraction and focalisation patterns linked to the geometry of the basin. Time and frequency analysis reveal some interesting features both in terms of amplification and energy residence in the basin. The low frequency amplification pattern is mainly controlled by the early response of the basin to the incident plane wave while the high frequency amplification patterns result mainly from late arrivals where complex 3D wave diffraction phenomena are dominating and the memory of the initial excitation is lost. Interestingly enough, it is shown that H/V method correctly predict the low frequency amplification pattern when apply to the late part of the recorded seismograms. The complex high frequency amplification pattern is shown to be associated with surface wave generation at, and propagation from, sharp edges of the basin. Importance of 3D phenomena is assessed by comparison with simple 2D simulations. Significant differences in terms of time of residence, energy and amplification levels point out the interest of complete 3D modeling. In conclusions some of the limitations associated with the use of unstructured hexahedral meshes will be adressed. Despite the use of unstructured meshing tool, modeling the geometry of geological basins remain a complex and time consuming task. Possible extensions using more elaborate techniques like non conforming domain decomposition will be also discussed in conclusion.

  5. Molecular analysis of UAS(E), a cis element containing stress response elements responsible for ethanol induction of the KlADH4 gene of Kluyveromyces lactis.

    PubMed

    Mazzoni, C; Santori, F; Saliola, M; Falcone, C

    2000-01-01

    KlADH4 is a gene of Kluyveromyces lactis encoding a mitochondrial alcohol dehydrogenase activity, which is specifically induced by ethanol and insensitive to glucose repression. In this work, we report the molecular analysis of UAS(E), an element of the KlADH4 promoter which is essential for the induction of KlADH4 in the presence of ethanol. UAS(E) contains five stress response elements (STREs), which have been found in many genes of Saccharomyces cerevisiae involved in the response of cells to conditions of stress. Whereas KlADH4 is not responsive to stress conditions, the STREs present in UAS(E) seem to play a key role in the induction of the gene by ethanol, a situation that has not been observed in the related yeast S. cerevisiae. Gel retardation experiments showed that STREs in the KlADH4 promoter can bind factor(s) under non-inducing conditions. Moreover, we observed that the RAP1 binding site present in UAS(E) binds KlRap1p. PMID:10724480

  6. 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. PMID:21294008

  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. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Early cell response to contact with biomaterial's surface.

    PubMed

    Komorowski, Piotr; Walkowiak-Przybyło, Magdalena; Walkowiak, Bogdan

    2016-07-01

    Most biomaterials at present have sufficient mechanical properties; however compliance with standards for biocompatibility is often not sufficient in clinical practice. This may be due to the complexity of biological systems in general and the diversity of individual responses to these materials by implant recipients. Significant improvement of biocompatibility must involve surface modification of implants, which in the future will make it possible to introduce individually selected types of surface modification for individual recipients. The key to this technology seems to be understanding the processes occurring at the site of contact of the implant with the tissue. Processes resulting from the stress generated by the contact of the biomaterial surfaces were observed with endothelial cells line EA.hy926, and it was demonstrated that differently modified surfaces of medical steel (polished medical steel and medical steel coated with Parylene C and nanocrystalline diamond) cause diverse cellular response in cells grown on these surfaces, on both the cellular (cell morphology and cell survival) and molecular (transcriptome and proteome profiles) levels. The herein presented observations are a good starting point not only for further research and the development of far-reaching personalization of medical implants, but also to study the potential use of cells as a specific sensor capable of recognizing different surfaces with which these cells come into contact. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 880-893, 2016. PMID:25951795

  14. 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.

  15. 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.

  16. 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.

  17. General frequency response program calculates frequency response of system, open at any specified element

    NASA Technical Reports Server (NTRS)

    Prosch, J.

    1967-01-01

    The general frequency response program provides the frequency response of any linear feedback control system including the open loop control system. The system characteristic matrix, obtained from the Laplace transformations of the dynamic and control equations, is input to the program. A variety of outputs are available.

  18. 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

  19. The Nrf2-antioxidant response element pathway: a target for regulating energy metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The nuclear factor E2-related factor 2 (Nrf2) is a transcription factor that responds to oxidative stress by binding to the antioxidant response element (ARE) in the promoter of genes coding for antioxidant enzymes like NAD(P)H:quinone oxidoreductase 1 (NQO1) and proteins for glutathione synthesis. ...

  20. Synergistic action of thermoresponsive and hygroresponsive elements elicits rapid and directional response of a bilayer actuator.

    PubMed

    Zhang, Lidong; Desta, Israel; Naumov, Panče

    2016-05-21

    A bilayer actuator composed of thermoresponsive and thermo/hygroresponsive elements is developed, which undergoes fast, directional and autonomous curling with a speed of up to 0.7 m s(-1) and recovers its shape by hydration. In situ tensile testing of the thermal response of individual layers provided insights into the mechanism of actuation of thermo/hygromorphic bilayers. PMID:26997588

  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. Functional analysis of the stress response element and its role in the multistress response of Saccharomyces cerevisiae.

    PubMed

    Treger, J M; Magee, T R; McEntee, K

    1998-02-01

    The DDR2 gene of Saccharomyces cerevisiae is a multistress response gene whose transcription is rapidly and strongly induced by a diverse array of xenobiotic agents, and environmental and physiological conditions. The multistress response of this gene requires the pentanucleotide, 5' CCCCT, (C4T;STRE (STress Response Element)) and the zinc-finger transcription factors, Msn2p and Msn4p. A 51bp oligonucleotide (oligo 31/32) containing two STREs from the DDR2 promoter region was previously shown to direct heat shock activation of a lacZ reporter gene. In this work we demonstrate that the same element conferred a complete multistress response to an E. coli galK reporter gene introduced into yeast cells. A variant oligonucleotide in which both the STRE spacing and neighboring sequences were altered responded to the same spectrum of stresses, while substitution of nucleotides within the pentanucleotide completely abolished the multistress response. These results directly demonstrate that STREs are not only necessary but are sufficient for mediating a transcriptional response to a surprisingly diverse set of environmental and physiological conditions. PMID:9473471

  3. 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.

  4. 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.

  5. Effect of surface morphology on drag and roughness sublayer in flows over regular roughness elements

    NASA Astrophysics Data System (ADS)

    Placidi, Marco; Ganapathisubramani, Bharathram

    2014-11-01

    The effects of systematically varied roughness morphology on bulk drag and on the spatial structure of turbulent boundary layers are examined by performing a series of wind tunnel experiments. In this study, rough surfaces consisting of regularly and uniformly distributed LEGO™ bricks are employed. Twelve different patterns are adopted in order to methodically examine the individual effects of frontal solidity (λF, frontal area of the roughness elements per unit wall-parallel area) and plan solidity (λP, plan area of roughness elements per unit wall-parallel area), on both the bulk drag and the turbulence structure. A floating element friction balance based on Krogstad & Efros (2010) was designed and manufactured to measure the drag generated by the different surfaces. In parallel, high resolution planar and stereoscopic Particle Image Velocimetry (PIV) was applied to investigate the flow features. This talk will focus on the effects of each solidity parameter on the bulk drag and attempt to relate the observed trends to the flow structures in the roughness sublayer. Currently at City University London.

  6. Using periodic analytic elements to analyze aquifer tests near surface waters

    NASA Astrophysics Data System (ADS)

    Kelson, Vic; Bakker, Mark

    2013-02-01

    In riverbank filtration (RBF), the objective is to indirectly pump water from a river into wells near the river, by inducing recharge through the river sediments. Design models must quantify the rate of induced infiltration from surface waters, which is often controlled by the hydraulic resistance between the surface water body and the aquifer. Traditional tools for aquifer-test analysis near surface streams have limited utility for directly estimating the resistance of a streambed or riverbed. The authors have developed software tools for aquifer test analysis using an analytic element model for periodically varying flow called Wigaem. The Wigaem code can explicitly represent the plan-view geometry of surface streams and the aquifer perimeter, including tributary streams when necessary. All boundary conditions in the model may vary periodically, including water levels in surface waters and pumping rates of wells in the simulation. A constant-discharge pumping test may be simulated by extending the pumping regime in time such that it becomes periodic and the total discharge during the period of simulation equals zero. Problems caused by the Gibbs phenomenon are reduced through application of a moving average filter, which makes Wigaem suitable for very general aquifer test problems. By calibrating the model to match observed water-level data, the model is used to estimate the transmissivity, storativity, and the entry resistance of surface waters, which are crucial for the design of RBF systems. This approach is applied to a site in central Illinois, United States.

  7. Responses of trace elements to aerobic maximal exercise in elite sportsmen.

    PubMed

    Otag, Aynur; Hazar, Muhsin; Otag, Ilhan; Gürkan, Alper Cenk; Okan, Ilyas

    2014-05-01

    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

  8. 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

  9. Protein-surface interactions on stimuli-responsive polymeric biomaterials.

    PubMed

    Cross, Michael C; Toomey, Ryan G; Gallant, Nathan D

    2016-04-01

    Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications. PMID:26942693

  10. 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.

  11. Regulation of expression of the stress response gene, Osp94: identification of the tonicity response element and intracellular signalling pathways.

    PubMed Central

    Kojima, Ryoji; Randall, Jeffrey D; Ito, Eri; Manshio, Hiroyuki; Suzuki, Yoshio; Gullans, Steven R

    2004-01-01

    Osp94 (osmotic stress protein of 94 kDa) is known to be up-regulated by hypertonic and heat-shock stresses in mouse renal inner medullary collecting duct (mIMCD3) cells. To investigate the molecular mechanism of transcriptional regulation of the Osp94 gene under these stresses, we cloned and characterized the 5'-flanking region of the gene. Sequence analysis of the proximal 4 kb 5'-flanking region revealed a TATA-less G/C-rich promoter region containing a cluster of Sp1 sites. We also identified upstream sequence motifs similar to the consensus TonE/ORE (tonicity-response element/osmotic response element) as well as the consensus HSE (heat-shock element). Luciferase activities in cells transfected with reporter constructs containing a TonE/ORE-like element (Osp94-TonE; 5'-TGGAAAGGACCAG-3') and HSE enhanced reporter gene expression under hypertonic stress and heat-shock stress respectively. Electrophoretic gel mobility-shift assay showed a slowly migrating band binding to the Osp94-TonE probe, probably representing binding of TonEBP (TonE binding protein) to this enhancer element. Furthermore, treatment of mIMCD3 cells with MAPK (mitogen-activated protein kinase) inhibitors (SB203580, PD98059, U0126 and SP600125) and a proteasome inhibitor (MG132) suppressed the increase in Osp94 gene expression caused by hypertonic NaCl. These results indicate that the 5'-flanking region of Osp94 gene contains a hypertonicity sensitive cis -acting element, Osp94-TonE, which is distinct from a functional HSE. Furthermore, the MAPK and proteasome systems appear to be, at least in part, involved in hypertonic-stressmediated regulation of Osp94 through Osp94-TonE. PMID:15018608

  12. Surface reactivity in the pathogenic response to particulates.

    PubMed Central

    Fubini, B

    1997-01-01

    The peculiar characteristics of dust toxicity are discussed in relation to the processes taking place at the particle-biological medium interface. Because of surface reactivity, toxicity of solids is not merely predictable from chemical composition and molecular structure, as with water soluble compounds. With particles having the same bulk composition, micromorphology (the thermal and mechanical history of dust and adsorption from the environment) determines the kind and abundance of active surface sites, thus modulating reactivity toward cells and tissues. The quantitative evaluation of doses is discussed in comparisons of dose-response relationships obtained with different materials. Responses related to the surface of the particle are better compared on a per-unit surface than per-unit weight basis. The role of micromorphology, hydrophilicity, and reactive surface cations in determining the pathogenicity of inhaled particles is described with reference to silica and asbestos toxicity. Heating crystalline silica decreases hydrophilicity, with consequent modifications in membranolytic potential, retention, and transport. Transition metal ions exposed at the surface generate free radicals in aqueous suspensions. Continuous redox cycling of iron, with consequent activation-reactivation of the surface sites releasing free radicals, could account for the long-term pathogenicity caused by the inhalation of iron-containing fibers. In various pathogenicities caused by mixed dusts, the contact between components modifies toxicity. Hard metal lung disease is caused by exposure to mixtures of metals and carbides, typically cobalt (Co) and tungsten carbide (WC), but not to single components. Toxicity stems from reactive oxygen species generation in a mechanism involving both Co metal and WC in mutual contact. A relationship between the extent of water adsorption and biopersistence is proposed for vitreous fibers. Modifications of the surface taking place in vivo are

  13. Wettability and cellular response of UV light irradiated anodized titanium surface

    PubMed Central

    Park, Kyou-Hwa; Koak, Jai-Young; Kim, Seong-Kyun

    2011-01-01

    PURPOSE The object of this study was to investigate the effect of UV irradiation (by a general commercial UV sterilizer) on anodized titanium surface. Surface characteristics and cellular responses were compared between anodized titanium discs and UV irradiated anodized titanium discs. MATERIALS AND METHODS Titanium discs were anodized and divided into the following groups: Group 1, anodized (control), and Group 2, anodized and UV irradiated for 24 hours. The surface characteristics including contact angle, roughness, phase of oxide layer, and chemical elemental composition were inspected. The osteoblast-like human osteogenic sarcoma (HOS) cells were cultured on control and test group discs. Initial cellular attachment, MTS-based cell proliferation assay, and ALP synthesis level were compared between the two groups for the evaluation of cellular response. RESULTS After UV irradiation, the contact angle decreased significantly (P<.001). The surface roughness and phase of oxide layer did not show definite changes, but carbon showed a considerable decrease after UV irradiation. Initial cell attachment was increased in test group (P=.004). Cells cultured on test group samples proliferated more actively (P=.009 at day 2, 5, and 7) and the ALP synthesis also increased in cells cultured on the test group (P=.016 at day 3, P=.009 at day 7 and 14). CONCLUSION UV irradiation induced enhanced wettability, and increased initial cellular responses of HOS cells on anodized titanium surface. PMID:21814613

  14. 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

  15. Efficient directional excitation of surface plasmons by a single-element nanoantenna

    NASA Astrophysics Data System (ADS)

    Yao, Wenjie; Liu, Shang; Liao, Huimin; Li, Zhi; Sun, Chengwei; Chen, Jianjun; Gong, Qihuang

    Directional light scattering is important in basic research and real applications. This area has been successfully downscaled to wavelength and subwavelength scales with the development of optical antennas, especially single-element nanoantennas. Here we show, by adding an auxiliary resonant structure to a single-element plasmonic nanoantenna, the highly efficient lowest-order antenna mode can be effectively transferred into inactive higher-order modes. Based on this mode conversion, scattered optical fields can be well manipulated by utilizing the interference between different antenna modes. Both broadband directional excitation of surface plasmon polaritons (SPPs) and inversion of SPP launching direction at different wavelengths are experimentally demonstrated as typical examples. The proposed strategy based on mode conversion and mode interference provides new opportunities for the design of nanoscale optical devices, especially directional nanoantennas.

  16. Surface-active element effects on the shape of GTA, laser, and electron-beam welds

    SciTech Connect

    Heiple, C.R.; Roper, J.R.; Stagner, R.T.; Aden, R.J.

    1983-03-01

    Laser and electron-beam welds were passed across selenium-doped zones in 21-6-9 stainless steel. The depth/width (d/w) ratio of a defocused laser weld with a weld pool shape similar to a GTA weld increased by over 200% in a zone where 66 ppm selenium had been added. Smaller increases were observed in selenium-doped zones for a moderately defocused electron beam weld with a higher d/w ratio in undoped base metal. When laser or electron beam weld penetration was by a keyhole mechanism, no change in d/w ratio occurred in selenium-doped zones. The results confirm the surface-tension-driven fluid-flow model for the effect of minor elements on GTA weld pool shape. Other experimental evidence bearing on the effect of minor elements on GTA weld penetration is summarized.

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Sumetsky, M.

    2016-05-01

    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 design of a miniature tunable optical delay line and a miniature tunable dispersion compensator is presented. The potential application of the suggested model to the design of a miniature optical buffer is discussed.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Role of surface-active elements during keyhole-mode laser welding

    NASA Astrophysics Data System (ADS)

    Ribic, B.; Tsukamoto, S.; Rai, R.; DebRoy, T.

    2011-12-01

    During high power density laser welding of mild steel, the keyhole depth, liquid metal flow, weld geometry and weld integrity are affected by base-metal sulfur content and oxygen (O2) present in the atmosphere or shielding gas. The role of these surface-active elements during keyhole-mode laser welding of steels is not well understood. In order to better understand their effects, welding of mild steel specimens containing various concentrations of oxygen and sulfur are examined. In addition, a numerical model is used to evaluate the influence of the surface-active elements on heat transfer and fluid flow in keyhole-mode laser welding. Increase in base-metal sulfur concentration or O2 content of shielding gas results in decreased weld widths. Sulfur results in a negligible increase in penetration depth whereas the presence of O2 in shielding gas significantly affects the weld penetration. It has earlier been proposed that oxygen, if present in the shielding gas, can get introduced into the weld pool resulting in formation of carbon monoxide (CO) at the keyhole surface and additional pressure from CO can result in increased penetration. Numerical modelling has been used in this work to understand the effects of formation of CO on the keyhole and weld geometries.

  4. Elemental characterization of the airborne pollen surface using Electron Probe Microanalysis (EPMA)

    NASA Astrophysics Data System (ADS)

    Duque, Laura; Guimarães, Fernanda; Ribeiro, Helena; Sousa, Raquel; Abreu, Ilda

    2013-08-01

    Recent worldwide increase in pollinoses has been attributed to the synergy between pollen and pollutants. We used EPMA for the elemental characterization of the airborne pollen surface in order to find out what occurs to the wall of pollen grains when they are together with other atmospheric pollutants. Analyses were performed both to airborne pollen and to pollen that was collected from Acer spp., Platanus spp. and Pinus spp. trees. Airborne samples were assembled using a Hirst-type volumetric spore sampler set in the coastal city of Porto, Portugal. Airborne pollen samples showed major elemental differences when compared to the control pollen sample of the same species, namely in the amounts of Cl, Na and Mg, which very significantly increased on airborne samples, revealing an important influence of the ocean. Mineral dust also contributed to modify the pollen surface, by increasing Si contents on Acer spp. and Platanus spp. airborne pollen. Our results revealed consistent positive effects of the relative humidity and the precipitation in the increase of Cl, Na and Mg relative amounts on the pollen surface. This study shows that pollen grains have the ability to adsorb and/or absorb other materials, which may contribute to enhance pollen's harmful effects on people's health.

  5. Comparison of Finite Element Non-Linear Beam Random Response with Experimental Results

    NASA Astrophysics Data System (ADS)

    Chen, R. R.; Mei, C.; Wolfe, HF

    1996-09-01

    A finite element formulation combined with the equivalent linearization technique and normal mode method is developed for the non-linear random response of beams subjected to acoustic and thermal loads applied simultaneously. To validate the present formulation and solution procedure, results are compared with the classical continuum solution and the Fokker-Planck-Kolmogorov equation solution. Comparison is also made with experimental data for a pre-stretched clamped beam. Random responses of thermally buckled simply supported beam, clamped beam and simply supported-clamped beam are presented. The comparison of the present simultaneously loaded response with the existing sequentially loaded results shows a significant difference between them.

  6. Infrasound-array-element frequency response: in-situ measurement and modeling

    NASA Astrophysics Data System (ADS)

    Gabrielson, T.

    2011-12-01

    Most array elements at the infrasound stations of the International Monitoring System use some variant of a multiple-inlet pipe system for wind-noise suppression. These pipe systems have a significant impact on the overall frequency response of the element. The spatial distribution of acoustic inlets introduces a response dependence that is a function of frequency and of vertical and horizontal arrival angle; the system of inlets, pipes, and summing junctions further shapes that response as the signal is ducted to the transducer. In-situ measurements, using a co-located reference microphone, can determine the overall frequency response and diagnose problems with the system. As of July 2011, the in-situ frequency responses for 25 individual elements at 6 operational stations (I10, I53, I55, I56, I57, and I99) have been measured. In support of these measurements, a fully thermo-viscous model for the acoustics of these multiple-inlet pipe systems has been developed. In addition to measurements at operational stations, comparative analyses have been done on experimental systems: a multiple-inlet radial-pipe system with varying inlet hole size; a one-quarter scale model of a 70-meter rosette system; and vertical directionality of a small rosette system using aircraft flyovers. [Funded by the US Army Space and Missile Defense Command

  7. Response Mechanism for Surface Acoustic Wave Gas Sensors Based on Surface-Adsorption

    PubMed Central

    Liu, Jiansheng; Lu, Yanyan

    2014-01-01

    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. PMID:24743157

  8. Finite-element simulation of transient heat response in ultrasonic transducers.

    PubMed

    Ando, E; Kagawa, Y

    1992-01-01

    The application of the finite-element method to a transient heat response problem in electrostrictive ultrasonic transducers during their pulsed operation is described. The temperature and thermal stress distribution are of practical importance for the design of the ultrasonic transducers when they are operated at intense levels. Mechanical vibratory loss is responsible for heat in the elastic parts, while dielectric loss is responsible in the ferroelectric parts. A finite-element computer model is proposed for the temperature change evaluation in the transducers with time. Natural and forced cooling convection and heat radiation from the transducers' boundaries are included. Simulation is made for Langevin-type transducer models, for which comparison is made with experimental data. PMID:18267653

  9. Effect of Surface Nanotopography on Bone Response to Titanium Implant.

    PubMed

    Freitas, Gileade P; Lopes, Helena B; Martins-Neto, Evandro C; de Oliveira, Paulo T; Beloti, Marcio M; Rosa, Adalberto L

    2016-06-01

    Clinical success of implant therapy is directly related to titanium (Ti) surface properties and the quality of bone tissue. The treatment of Ti implants with H2SO4/H2O2 is a feasible, reproducible, and low-cost technique to create surface nanotopography (Ti-Nano). As this nanotopography induces osteoblast differentiation, we hypothesized that it may affect bone response to Ti. Thus, this study was designed to evaluate the bone response to a machined Ti implant treated with H2SO4/H2O2 to generate Ti-Nano and to compare it with a commercially available microtopographic Ti implant (Ti-Porous). Implants were placed in rabbit tibias and evaluated after 2 and 6 weeks, and the bone tissue formed around them was assessed by microtomography to record bone volume, bone surface, specific bone surface, trabecular number, trabecular thickness, and trabecular separation. Undecalcified histological sections were used to determine the percentages of bone-to-implant contact, bone area formed between threads, and bone area formed in the mirror area. At the end of 6 weeks, the removal torque was evaluated using a digital torque gauge. The results showed bone formation in close contact with both Ti-Nano and Ti-Porous implants without relevant morphological and morphometric differences, in addition to a similar removal torque irrespective of surface topography. In conclusion, our results have shown that a simple and low-cost method using H2SO4/H2O2 is highly efficient for creating nanotopography on Ti surfaces, which elicits a similar bone response compared with microtopography presented in a commercially available Ti implant. PMID:26390195

  10. 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

  11. 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.

  12. 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.

  13. Parameter variability estimation using stochastic response surface model updating

    NASA Astrophysics Data System (ADS)

    Fang, Sheng-En; Zhang, Qiu-Hu; Ren, Wei-Xin

    2014-12-01

    From a practical point of view, uncertainties existing in structural parameters and measurements must be handled in order to provide reliable structural condition evaluations. At this moment, deterministic model updating loses its practicability and a stochastic updating procedure should be employed seeking for statistical properties of parameters and responses. Presently this topic has not been well investigated on account of its greater complexity in theoretical configuration and difficulty in inverse problem solutions after involving uncertainty analyses. Due to it, this paper attempts to develop a stochastic model updating method for parameter variability estimation. Uncertain parameters and responses are correlated through stochastic response surface models, which are actually explicit polynomial chaos expansions based on Hermite polynomials. Then by establishing a stochastic inverse problem, parameter means and standard deviations are updated in a separate and successive way. For the purposes of problem simplification and optimization efficiency, in each updating iteration stochastic response surface models are reconstructed to avoid the construction and analysis of sensitivity matrices. Meanwhile, in the interest of investigating the effects of parameter variability on responses, a parameter sensitivity analysis method has been developed based on the derivation of polynomial chaos expansions. Lastly the feasibility and reliability of the proposed methods have been validated using a numerical beam and then a set of nominally identical metal plates. After comparing with a perturbation method, it is found that the proposed method can estimate parameter variability with satisfactory accuracy and the complexity of the inverse problem can be highly reduced resulting in cost-efficient optimization.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. A finite element large deflection random response analysis of beams and plates subjected to acoustic loading

    NASA Technical Reports Server (NTRS)

    Mei, Chuh; Chiang, C. K.

    1987-01-01

    A finite element formulation is presented for the analysis of beams and rectangular plates undergoing large deflections subjected to Gaussian white noise excitations. Single-mode response is assumed in the present formulation. Root-mean-square (RMS) maximum deflections for simply supported and clamped beams and plates at various sound spectrum levels are obtained and compared with solutions using the Fokker-Planck-Kolmogorov equation and the equivalent linearization methods. RMS maximum stains and equivalent linear frequencies are compared with the equivalent linearization results for assessment of the accuracy of the finite element method.

  2. Polycomb/Trithorax response elements and epigenetic memory of cell identity.

    PubMed

    Ringrose, Leonie; Paro, Renato

    2007-01-01

    Polycomb/Trithorax group response elements (PRE/TREs) are fascinating chromosomal pieces. Just a few hundred base pairs long, these elements can remember and maintain the active or silent transcriptional state of their associated genes for many cell generations, long after the initial determining activators and repressors have disappeared. Recently, substantial progress has been made towards understanding the nuts and bolts of PRE/TRE function at the molecular level and in experimentally mapping PRE/TRE sites across whole genomes. Here we examine the insights, controversies and new questions that have been generated by this recent flood of data. PMID:17185323

  3. Dynamic Response of a Planetary Gear System Using a Finite Element/Contact Mechanics Model

    NASA Technical Reports Server (NTRS)

    Parker, Robert G.; Agashe, Vinayak; Vijayakar, Sandeep M.

    2000-01-01

    The dynamic response of a helicopter planetary gear system is examined over a wide range of operating speeds and torques. The analysis tool is a unique, semianalytical finite element formulation that admits precise representation of the tooth geometry and contact forces that are crucial in gear dynamics. Importantly, no a priori specification of static transmission error excitation or mesh frequency variation is required; the dynamic contact forces are evaluated internally at each time step. The calculated response shows classical resonances when a harmonic of mesh frequency coincides with a natural frequency. However, peculiar behavior occurs where resonances expected to be excited at a given speed are absent. This absence of particular modes is explained by analytical relationships that depend on the planetary configuration and mesh frequency harmonic. The torque sensitivity of the dynamic response is examined and compared to static analyses. Rotation mode response is shown to be more sensitive to input torque than translational mode response.

  4. Modelling elements for the Moon s near surface dusty plasma environment characterization

    NASA Astrophysics Data System (ADS)

    Cipriani, F.; Hilgers, A. M.

    2011-12-01

    F. Cipriani (1), A. Hilgers(1), D. Rodgers(1) (1) ESA/ESTEC, Noordwijk, The Netherlands (fabrice.cipriani@esa.int / Fax: +31-71-5654697) Characterizing the Moon's electrostatically charged regolith, the levitation and transport of charged dust grains and their role in the surface current balance, is of primary importance to prepare future lunar missions. Observations carried out during Apollo missions brought evidence for a dust levitation process [1] and allowed to study lunar grains charging characteristics [2]. Lately, Lunar Prospector electron reflectometry data allowed to gain insights into the magnitude and the variability of lunar surface charging, revealing significant electrostatic potentials under different plasma conditions, depending on the Moon's local environment (Solar Wind, tail lobes, Earth's plasma sheet) (see e.g. [3,4]). Although theoretical studies have tackled the problem of regolith and dust grains charging, numerical modeling tools can be useful to simulate dust charging and transport over the complex features of the lunar topography, including the effects of the near surface magnetic environment, and interaction with mission elements as a lunar lander [5]. In the present study we use on the one hand a 3D PIC simulation code to investigate, under simplifying assumptions: 1) charging of the lunar surface under different plasma conditions encountered along the Moon orbit, 2) charging of a complex surface feature (typically a crater), and 3) charging, levitation and transport of dust grains in the near surface environment. One the other hand, we analyze limitations of the current tool and the physics to be further implemented in order to address dust charging and transport processes at the Moon surface relevant to the exploration of the Moon. References [1] Stubbs et al, (2006) Advance in Space Research, 37, 59-66 [2] Horanyi et al, (1998) JGR, Volume 103, Issue E4 [3] Halekas et al, (2008) JGR, Volume 113, Issue A9 [4] Poppe et al, (2011) GRL

  5. 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

  6. 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

  7. Intelligent detection of cracks in metallic surfaces using a waveguide sensor loaded with metamaterial elements.

    PubMed

    Ali, Abdulbaset; Hu, Bing; Ramahi, Omar

    2015-01-01

    This work presents a real life experiment of 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 impact in terms of sensing sensitivity, cost, and automation. Furthermore, applying artificial intelligence for post-processing 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 obtained experimental results showed good crack classification accuracy rates. PMID:25988871

  8. 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.

  9. 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.

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

    SciTech Connect

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

    2011-01-17

    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 CO{sub 2} 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 {mu}m and 150 {mu}m. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 {mu}m. The maximum hardness achieved was between 728 and 905 HV{sub 0.1}. These findings are significant to modern development of hard coatings for wear resistant applications.

  11. Chemical Weathering of Black Shales and Rare Earth Element Composition of Surface Waters and Groundwater

    NASA Astrophysics Data System (ADS)

    Hannigan, R. E.; Johannesson, K. H.

    2001-05-01

    Weathering processes dominate the dissolved and suspended loads of most of the world's major rivers. Among sedimentary rocks, black shales are particularly sensitive to chemical weathering. Therefore, shale systems are useful for investigating the partitioning of chemical elements during chemical weathering. Recent studies, such as those by Peucker-Ehrenbrink, Ravizza and others, link chemical weathering of black shales to changes in marine isotopic composition. Rare earth elements (REE) have a unique chemistry and are ideal for such tracer studies. We explored the effect of modern chemical weathering of black shales on the hydrochemistry of surface and groundwaters in the Mohawk Valley of New York State. This region provides an ideal site for the investigation of trace element remobilization during the chemical weathering of black shales. In this region, surface and groundwaters, in intimate contact with black shales and have high dissolved metal concentrations presumably due to water-rock interactions. The extent to which the dissolved REE composition of the surface and ground waters retains the rock signature is, in someway related to the length of time that the water remains in contact with the rock. We compared the REE compositions of surface and groundwaters in areas draining black shale to those of waters draining regions of dolostone-limestone to explore the extent of metal release due to chemical weathering. Shale normalized REE patterns for stream waters exhibit slight heavy REE enrichments and, at some locations, LREE depletion. REE patterns of the waters normalized to their respective sediments show some LREE depletion. However, waters associated with the Little Falls dolomite show fractionation predominantly enriched in the heavy REEs. Differences between the black shale sites, recorded as light REE depletion and/or middle REE enrichment, may be related to the discharge of the streams and the total dissolved solids. The dissolved REE chemistry of

  12. 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

  13. 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

  14. 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

  15. Finite element model updating of a RC building considering seismic response trends

    NASA Astrophysics Data System (ADS)

    Butt, F.; Omenzetter, P.

    2013-04-01

    This paper presents a study on the seismic response trends evaluation and finite element model updating of a reinforced concrete building monitored for a period of more than two years. The three story reinforced concrete building is instrumented with five tri-axial accelerometers and a free-field tri-axial accelerometer. The time domain N4SID system identification technique was used to obtain the frequencies and damping ratios considering flexible base models taking into account the soil-structure-interaction using 50 earthquakes. Trends of variation of seismic response were developed by correlating the peak response acceleration at the roof level with identified frequencies and damping ratios. A general trend of decreasing frequencies was observed with increased level of shaking. To simulate the varying behavior of the building with response levels, a series of three dimensional finite element models were calibrated considering several points on the developed frequency-response amplitude trend lines as targets for updating. To incorporate real in-situ conditions, soil underneath the foundation and around the building was modeled using spring elements and nonstructural components (claddings and partitions) were also included. Sensitivity based model updating technique was applied taking into account concrete, soil and cladding stiffness as updating parameters. It was concluded from the investigation that knowledge of the variation of seismic response of buildings is necessary to better understand their behavior during earthquakes, and also that the participation of soil and non-structural components is significant towards the seismic response of the building and these should be considered in models to simulate the real behavior.

  16. 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.

  17. Response of hot element wall shear stress gages in laminar oscillating flows

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    An experimental investigation of the time-dependent response of hot element wall shear stress gages in unsteady periodic air flows is reported. The study has focused on wall shear stress in laminar oscillating flows produced on a flat plate by a free stream velocity composed of a mean component and a superposed sinusoidal variation. Two types of hot element gages, platinum film and flush wire, were tested for values of reduced frequency ranging from 0.14 to 2.36. Values of the phase angle of the wall shear stress variation relative to the free stream velocity, as indicated by the hot element gages, are compared with numerical prediction. The comparisons show that the gages indicate a wall shear stress variation that lags the true variation, and that the gages will also not indicate the correct wall shear stress variation in periodic turbulent flows.

  18. The quest for mammalian Polycomb response elements: are we there yet?

    PubMed

    Bauer, Moritz; Trupke, Johanna; Ringrose, Leonie

    2016-06-01

    A long-standing mystery in the field of Polycomb and Trithorax regulation is how these proteins, which are highly conserved between flies and mammals, can regulate several hundred equally highly conserved target genes, but recognise these targets via cis-regulatory elements that appear to show no conservation in their DNA sequence. These elements, termed Polycomb/Trithorax response elements (PRE/TREs or PREs), are relatively well characterised in flies, but their mammalian counterparts have proved to be extremely difficult to identify. Recent progress in this endeavour has generated a wealth of data and raised several intriguing questions. Here, we ask why and to what extent mammalian PREs are so different to those of the fly. We review recent advances, evaluate current models and identify open questions in the quest for mammalian PREs. PMID:26453572

  19. 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

  20. 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.

  1. Extracellular polymeric substances govern the surface charge of biogenic elemental selenium nanoparticles.

    PubMed

    Jain, Rohan; Jordan, Norbert; Weiss, Stephan; Foerstendorf, Harald; Heim, Karsten; Kacker, Rohit; Hübner, René; Kramer, Herman; van Hullebusch, Eric D; Farges, François; Lens, Piet N L

    2015-02-01

    The origin of the organic layer covering colloidal biogenic elemental selenium nanoparticles (BioSeNPs) is not known, particularly in the case when they are synthesized by complex microbial communities. This study investigated the presence of extracellular polymeric substances (EPS) on BioSeNPs. The role of EPS in capping the extracellularly available BioSeNPs was also examined. Fourier transform infrared (FT-IR) spectroscopy and colorimetric measurements confirmed the presence of functional groups characteristic of proteins and carbohydrates on the BioSeNPs, suggesting the presence of EPS. Chemical synthesis of elemental selenium nanoparticles in the presence of EPS, extracted from selenite fed anaerobic granular sludge, yielded stable colloidal spherical selenium nanoparticles. Furthermore, extracted EPS, BioSeNPs, and chemically synthesized EPS-capped selenium nanoparticles had similar surface properties, as shown by ζ-potential versus pH profiles and isoelectric point measurements. This study shows that the EPS of anaerobic granular sludge form the organic layer present on the BioSeNPs synthesized by these granules. The EPS also govern the surface charge of these BioSeNPs, thereby contributing to their colloidal properties, hence affecting their fate in the environment and the efficiency of bioremediation technologies. PMID:25536371

  2. Thermoelastic finite element analysis of subsurface cracking due to sliding surface traction

    SciTech Connect

    Cho, S.S.; Komvopoulos, K.

    1997-01-01

    A linear elastic fracture mechanics analysis of subsurface crack propagation in a half-space subjected to moving thermomechanical surface traction was performed using the finite element method. The effect of frictional heating at the sliding surface on the crack growth behavior is analyzed in terms of the coefficient of friction, crack length-to-depth ratio, and Peclet number. The crack propagation characteristics are interpreted in light of results for the directions and magnitudes of the maximum shear and tensile stress intensity factor ranges, respectively. It is shown that, while frictional heating exhibits a negligible effect on the crack propagation direction, it increases the in-plane crack growth rate and reduces the critical crack length at the onset of out-of-plane crack growth at the right tip due to the tensile mechanism (kink formation). The effect of frictional heating becomes more pronounced with increasing contact friction, crack length-to-depth ratio, and Peclet number. Crack mechanism maps showing the occurrence of opening, slip, and stick regions between the crack surfaces are presented for different values of crack length-to-depth ratio, coefficient of friction, and position of thermomechanical surface traction.

  3. 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

  4. 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 ...

  5. 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

  6. Effects of friction on the unconfined compressive response of articular cartilage: a finite element analysis.

    PubMed

    Spilker, R L; Suh, J K; Mow, V C

    1990-05-01

    A finite element analysis is used to study a previously unresolved issue of the effects of platen-specimen friction on the response of the unconfined compression test; effects of platen permeability are also determined. The finite element formulation is based on the linear KLM biphasic model for articular cartilage and other hydrated soft tissues. A Galerkin weighted residual method is applied to both the solid phase and the fluid phase, and the continuity equation for the intrinsically incompressible binary mixture is introduced via a penalty method. The solid phase displacements and fluid phase velocities are interpolated for each element in terms of unknown nodal values, producing a system of first order differential equations which are solved using a standard numerical finite difference technique. An axisymmetric element of quadrilateral cross-section is developed and applied to the mechanical test problem of a cylindrical specimen of soft tissue in unconfined compression. These studies show that interfacial friction plays a major role in the unconfined compression response of articular cartilage specimens with small thickness to diameter ratios. PMID:2345443

  7. Mineral Elements of Subtropical Tree Seedlings in Response to Elevated Carbon Dioxide and Nitrogen Addition

    PubMed Central

    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

  8. Finite-element simulation of transient heat response in ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Ando, Ei'ichi; Kagawa, Yukio

    1992-05-01

    The application of the finite-element method to a transient heat response problem in electrostrictive ultrasonic transducers during their pulsed operation is described. The temperature and thermal stress distribution are of practical importance for the design of the ultrasonic transducers when they are operated at intense levels. Mechanical vibratory loss is responsible for heat in the elastic parts while dielectric loss in the ferroelectric parts. A finite-element computer model is proposed for the temperature change evaluation in the transducers with time. Natural and forced cooling convection and heat radiation from the transducers' boundaries are included. Simulation is made for Langevin-type transducer models, for which comparison is made with experimental data.

  9. 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

    NASA Astrophysics Data System (ADS)

    Steward, David R.

    2015-11-01

    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, and elements with low conductivity retard flow with discontinuous head. Base flow interactions at the interface between groundwater and surface water transport water between these stores and generate a discontinuous normal component of flow. Thin objects in surface water with Kutta condition generate circulation by the discontinuous tangential component of flow across their interface. These discontinuities across hydrologic interfaces are quantified and visualized using the Analytic Element Method, where slit elements are formulated using the Joukowsky transformation with Laurent series and new influence functions to represent sinks and circulation, and methods are developed for these applications expressing discontinuities as Fourier series. The specific geometries illustrate solutions for a randomly generated heterogeneous porous media with nonintersecting inhomogeneities, for groundwater/surface water interaction in a synthetic river network, and for a slender body with geometry similar to the wings of the Wright Brothers. The mathematical details are reduced to series solutions and matrix multiplications, which are easily extensible to other geometries and applications.

  10. 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...

  11. 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

  12. 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.

  13. Finite element nonlinear random response of beams to acoustic and thermal loads applied simultaneously

    NASA Astrophysics Data System (ADS)

    Chen, Ruixi; Mei, Chuh

    1993-04-01

    A finite element formulation combined with the equivalent linearization technique and the normal mode method is developed for the study of nonlinear random response of beams subjected to simultaneously applied acoustic and thermal loads. Examples include thermally buckled random response of simply supported beam, clamped-clamped beam and simply supported-clamped beam. To compare and validate the present formulation, results are compared with the solutions from existing sequential load method, and significant difference has been found. Results by classical continuum solution and the solution of Fokker-Planck-Kolmogorov equation are also derived and obtained for comparison.

  14. Effect of randomness on multi-frequency aeroelastic responses resolved by Unsteady Adaptive Stochastic Finite Elements

    SciTech Connect

    Witteveen, Jeroen A.S. Bijl, Hester

    2009-10-01

    The Unsteady Adaptive Stochastic Finite Elements (UASFE) method resolves the effect of randomness in numerical simulations of single-mode aeroelastic responses with a constant accuracy in time for a constant number of samples. In this paper, the UASFE framework is extended to multi-frequency responses and continuous structures by employing a wavelet decomposition pre-processing step to decompose the sampled multi-frequency signals into single-frequency components. The effect of the randomness on the multi-frequency response is then obtained by summing the results of the UASFE interpolation at constant phase for the different frequency components. Results for multi-frequency responses and continuous structures show a three orders of magnitude reduction of computational costs compared to crude Monte Carlo simulations in a harmonically forced oscillator, a flutter panel problem, and the three-dimensional transonic AGARD 445.6 wing aeroelastic benchmark subject to random fields and random parameters with various probability distributions.

  15. 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

  16. On estimating frequency response function envelopes using the spectral element method and fuzzy sets

    NASA Astrophysics Data System (ADS)

    Nunes, R. F.; Klimke, A.; Arruda, J. R. F.

    2006-04-01

    The influence of uncertain input data on response spectra of dynamic structures is considered. Traditionally, frequency response analyses are based on finite or boundary element models of the objective structure. In the case of the mid-frequency range problem, however, a very fine mesh is required to correctly approximate the frequency response. This is particularly problematic in uncertainty modeling where the computational effort is usually increased significantly by the need for multiple runs (e.g. when conducting a Monte Carlo analysis) to achieve reliable results. In this paper, the spectral element method, combined with a fuzzy set-based uncertainty modeling approach, is presented as an appealing alternative, provided that the models are simple enough to yield a spectral element representation. To conduct the fuzzy analysis part, three different implementations of the extension principle of fuzzy arithmetic are applied and compared. The suitability of each method depends on the number of uncertain parameters, the problem characteristics, and the required accuracy of the results. The performance of the proposed approach is illustrated by two test problems, a simple coupled rod and a reinforced plate model. To verify the fuzzy-valued results, a Monte Carlo simulation has also been included.

  17. 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

  18. 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. PMID:26247827

  19. 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

  20. 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

  1. 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

  2. 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.

  3. Adsorption of nonmetallic elements on defect-free MgO(001) surface - DFT study

    NASA Astrophysics Data System (ADS)

    Pašti, Igor A.; Baljozović, Miloš; Skorodumova, Natalia V.

    2015-02-01

    Adsorption of 11 non-metals (H, B, C, N, O, F, Si, P, S, Cl and Br) on defect-free MgO(001) surface was investigate using DFT approach. Adsorption energies were found to be between - 0.56 eV (hydrogen adsorption) and - 2.63 eV (carbon adsorption). Charge transfer from substrate to adsorbate was observed to follow the periodicity in the Periodic Table of Elements, as increases from left to right and decreases from top to bottom. All investigated adsorbates prefer oxygen sites on MgO surface. The analysis of adsorbate-MgO(001) electronic structure suggested that the electronic structure of the O adsorption center and adsorbate atom is molecule-like and there is no strong interaction with MgO electronic bands. Based on the obtained dataset for adsorption energies of selected non-metallic adsorbates (X) the reactivity of MgO towards the bond cleavage in the cases of X-X, H-X and HO-X bonds was discussed. Obtained results point to weak reactivity of MgO(001) towards atomic adsorption and low activity for bond cleavage. However, these results can be used as a starting point for the functionalization of MgO, particularly in the cases where bond cleavage activity and surface-mediated stabilization of dissociation products are desired.

  4. 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. PMID:27040222

  5. 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

  6. 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.

  7. 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

  8. 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.

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

    PubMed

    Custer, Christine M; Custer, Thomas W; Warburton, David; Hoffman, David J; Bickham, John W; Matson, Cole W

    2006-07-01

    Extremely high concentrations of cadmium (3.5 microg/g dry wgt.) and elevated concentrations of chromium (>10 microg/g dry wgt.) and mercury (1.6 microg/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 microg/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. PMID:16897545

  10. 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

  11. 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.

  12. The 2004 Ultrasonic Benchmark Problem - SDH Response Under Oblique Incidence: Measurements and Patch Element Model Calculations

    SciTech Connect

    Krishnamurthy, C. V.; Shankar, M.; Vardhan, J. Vishnu; Balasubramaniam, Krishnan

    2006-03-06

    The 2004 ultrasonic benchmark problem requires models to predict, given a reference pulse waveform, the pulse echo response of cylindrical voids of various radii located in an elastic solid for various incidence angles of a transducer immersed in water. We present the results of calculations based on the patch element model, recently developed at CNDE, to determine the response of an SDH in aluminum for specific oblique incidence angles. Patch element model calculations for a scan across the SDH, involving a range of oblique incidence angles, are also presented. Measured pulse-echo scans involving the SDH response under oblique incidence conditions are reported. In addition, through transmission measurements involving a pinducer as a receiver and an immersion planar probe as a transmitter under oblique incidence conditions are also reported in a defect-free Aluminum block. These pinducer-based measurements on a defect-free block are utilised to characterize the fields at the chosen depth. Comparisons are made between predictions and measurements for the pulse-echo response of a SDH.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  19. 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

  20. Computational modeling of in vitro biological responses on polymethacrylate surfaces

    PubMed Central

    Ghosh, Jayeeta; Lewitus, Dan Y; Chandra, Prafulla; Joy, Abraham; Bushman, Jared; Knight, Doyle; Kohn, Joachim

    2011-01-01

    The objective of this research was to examine the capabilities of QSPR (Quantitative Structure Property Relationship) modeling to predict specific biological responses (fibrinogen adsorption, cell attachment and cell proliferation index) on thin films of different polymethacrylates. Using 33 commercially available monomers it is theoretically possible to construct a library of over 40,000 distinct polymer compositions. A subset of these polymers were synthesized and solvent cast surfaces were prepared in 96 well plates for the measurement of fibrinogen adsorption. NIH 3T3 cell attachment and proliferation index were measured on spin coated thin films of these polymers. Based on the experimental results of these polymers, separate models were built for homo-, co-, and terpolymers in the library with good correlation between experiment and predicted values. The ability to predict biological responses by simple QSPR models for large numbers of polymers has important implications in designing biomaterials for specific biological or medical applications. PMID:21779132

  1. Summer surface layer thermal response to surface gravity waves in the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Xuefeng; Han, Guijun; Wang, Dongxiao; Deng, Zengan; Li, Wei

    2012-07-01

    The Princeton Ocean Model (POM) with generalized coordinate system (POMgcs) is used to study the summer surface-layer thermal response to surface gravity waves in the Yellow Sea (YS). The parameterization schemes of wave breaking developed by Mellor and Blumberg (J Phys Oceanogr 34:693-698, 2004) and Kantha and Clayson (Ocean Model 6:101-124, 2004), respectively, and Stokes production developed by Kantha and Clayson (Ocean Model 6:101-124, 2004) are both included in the Mellor-Yamada turbulence closure model Mellor and Yamada (Rev Geophys 20:851-875, 1982) of POMgcs. Numerical results show that surface gravity waves impact the depth of surface mixed layer of temperature in the YS in summer. The surface mixed layer in the YS cannot be reproduced well and has a visible difference from the observation if the parameterization schemes are not included. A diagnostic analysis of turbulent kinetic energy suggests that both Stokes production and wave breaking play key roles in enhancing the turbulent mixing near the sea surface in the YS. Stokes production seems to have a greater impact throughout the upper mixed layer in the YS in summer than that of wave breaking. In addition, a diagnostic analysis of the momentum balance shows that Coriolis-Stokes forcing has a significant effect on the momentum budget in the upper layer in the YS, and surface gravity waves are able to reduce the velocity of mean flow near the surface and make the mean flow near the surface more homogeneous vertically in the YS.

  2. Environmental significance of biogenic elements in surface sediments of the Changjiang Estuary and its adjacent areas.

    PubMed

    Yu, Yu; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Duan, Liqin

    2013-11-01

    Biogenic elements and six phosphorus (P) fractions in surface sediments from the Changjiang Estuary and adjacent waters were determined to investigate the governing factors of these elements, and further to discuss their potential uses as paleo-environment proxies and risks of P release from sediment. Total organic carbon (TOC) and leachable organic P (Lea-OP) showed high concentrations in the estuary, Zhejiang coast and offshore upwelling area. They came from both the Changjiang River and marine biological input. Biogenic silicon (BSi) exhibited a high concentration band between 123 and 124 degree E. BSi mainly came from diatom production and its concentration in the inshore area was diluted by river sediment. Total nitrogen (TN) was primarily of marine biogenic origin. Seaward decreasing trends of Fe-bound P and Al-bound P revealed their terrestrial origins. Influenced by old Huanghe sediment delivered by the Jiangsu coastal current, the maximum concentration of detrital P (Det-P) was observed in the area north of the estuary. Similar high concentrations of carbonate fluorapatite (CFA-P) and CaCO3in the southern study area suggested marine calcium-organism sources of CFA-P. TOC, TN and non-apatite P were enriched in fine sediment, and Det-P partially exhibited coarse-grain enrichment, but BSi had no correlation with sediment grain size. Different sources and governing factors made biogenic elements and P species have distinct potential uses in indicating environmental conditions. Transferable P accounted for 14%-46% of total P. In an aerobic environment, there was low risk of P release from sediment, attributed to excess Fe oxides in sediments. PMID:24552046

  3. 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.

  4. 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.

  5. Nanoparticle-Functionalized Porous Polymer Monolith Detection Elements for Surface-Enhanced Raman Scattering

    PubMed Central

    Liu, Jikun; White, Ian; DeVoe, Don L.

    2011-01-01

    The use of porous polymer monoliths functionalized with silver nanoparticles is introduced in this work for high-sensitivity surface-enhanced Raman scattering (SERS) detection. Preparation of the SERS detection elements is a simple process comprising the synthesis of a discrete polymer monolith section within a silica capillary, followed by physically trapping silver nanoparticle aggregates within the monolith matrix. A SERS detection limit of 220 fmol for Rhodamine 6G (R6G) is demonstrated, with excellent signal stability over a 24 h period. The capability of the SERS-active monolith for label-free detection of biomolecules was demonstrated by measurements of bradykinin and cyctochrome c. The SERS-active monoliths can be readily integrated into miniaturized micro-total-analysis systems for on-line and label-free detection for a variety of biosensing, bioanalytical, and biomedical applications. PMID:21322579

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

    PubMed

    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((2)P) + HCl and F((2)P) + H2 reactions as model applications. Our publicly available code (http://www2.chem.umd.edu/groups/alexander/FEM) is general and easy to use. PMID:25612690

  7. Elements of the Chicxulub Impact Structure as Revealed in SRTM and Surface GPS Topographic Data

    NASA Technical Reports Server (NTRS)

    Kinsland, Gary L.; Sanchez, Gary; Kobrick, Michael; Cardador, Manuel Hurtado

    2003-01-01

    Pope et al. [1] utilized the elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxulub Impact Structure is a roughly semi-circular, lowrelief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact, which possibly led to the development of these features. These are summarized in Table 1. Kinsland et al. [2] presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Very recently we have acquired digital topography data from NASA s Shuttle Radar Topography Mission (SRTM). Our subset covers 6 square degrees from 20deg N 91degW to 22deg N 88degW (corner to corner) with a pixel size of about 90m. This area includes all of the identified portion of the crater on land.

  8. 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.

  9. Optimization of seabuckthorn fruit yogurt formulation using response surface methodology.

    PubMed

    Selvamuthukumaran, Meenakshisundaram; Khanum, Farhath

    2015-02-01

    The response surface methodology was used to optimize the formulation of seabuckthorn fruit yogurt. The independent variables were proportions of seabuckthorn fruit syrup and skimmed milk powder. The responses were counts of Streptococcus thermophilus and Lactobacillus bulgaricus, taste and viscosity of the product. Statistical analysis revealed that fruit syrup and skimmed milk powder significantly affected all the responses. Contour plots for each response were used to generate an optimum area by superimposition. Optimum formulation conditions of fruit syrup (15 %) and skimmed milk powder (12.5 %) are recommended for the blend formulation yielding an acceptable and good quality seabuckthorn fruit yogurt. Model validation was conducted using separate experiments at optimum conditions. The experimental values were found to be in close agreement to the predicted values and were within the acceptable limits indicating the suitability of the model in predicting quality attributes of seabuckthorn fruit yogurt. The resultant product also exhibited more amounts of fat, protein, carbohydrate and antioxidants viz., vitamin C, E, carotenoids, phenols and anthocyanins when compared to a commercial one. PMID:25694691

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Role of Nrf1 in antioxidant response element-mediated gene expression and beyond

    SciTech Connect

    Biswas, Madhurima; Chan, Jefferson Y.

    2010-04-01

    Oxidative stress plays an important part in the pathogenesis of a variety of diseases. The ability to mount an efficient response against the continuous threat posed by exogenous and endogenous oxidants is essential for cellular homeostasis and survival. Oxidative stress activates transcription of a variety of antioxidant genes through cis-acting sequence known as antioxidant response element (ARE). Members of the Cap-N-Collar family of transcription factors, including Nrf1 and Nrf2, that bind ARE have been identified. Nrf1 and Nrf2 are expressed in a wide range of tissues and cell types, and both bind the ARE as heterodimers with small Maf proteins. Numerous studies indicate a pivotal role of Nrf2 in ARE function. Herein, we review data derived from cell-based studies and knockout mice in an attempt to define the role and regulation of Nrf1 in oxidative stress response and other functions.

  16. Response of the atmospheric boundary layer to changes in surfaces fluxes

    NASA Astrophysics Data System (ADS)

    Owinoh, A. Z.; Hunt, J. C.; Orr, A.; Clark, P.

    2003-04-01

    The response of the atmospheric boundary layer (ABL) to varying surface fluxes such as surface heat fluxes and roughness changes is a common element in several problems in mesoscale dynamics. We study some of these problems by reducing the complexity of the physical processes that are relevant to mechanism of interest so that analytical solutions can be obtained. Our presentation begins with the examination of the time dependent response and the influence of a 2-D low hill on the flow in a neutral boundary layer to a uniform surface heat flux switched at time, t=0. Analytical solutions for changes in temperature, mean wind and shear stress profiles in the ABL are sought. The modelled profiles are compared with those obtained from the UK Unified Model run on a idealised mode at 12km horizontal resolution. To understand the time and spatial dependence, perturbations are analysed of stratified ABL equations as they pass over areas where there is sharply differing surface heat flux and roughness; a situation freqently observed between rural and urban areas, or across coastline or across sea-ice boundaries. New estimates are derived for the transition distance and how the fluxes, temperature and velocity, vary in the transition distance zone. These simple estimates are compared with Rider et al. (1963) experimental data. Rider N. E., Philip J. R. &Bradley E. F. (1963), The horizontal transport of heat and moisture - A micrometeorological study. Q. J. R. Meteorol. Soc, 89, 507-531.

  17. 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

  18. 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

  19. Surface analysis of commercially pure titanium implant retrieved from rat bone. Part 1: initial biological response of sandblasted surface.

    PubMed

    Watanabe, Kouichi; Okawa, Seigo; Kanatani, Mitugu; Homma, Kikuo

    2009-03-01

    To gain insight on the early biological response to commercial pure titanium (cpTi), the surface properties of cpTi implants retrieved from rat bone were examined by X-ray photoelectron spectroscopy (XPS). To this end, semi-cylindrical bullets, 1.1 mm in diameter and 3.5 mm in length, were implanted into the femurs of Wistar rats and then retrieved after either 3 hours or 7 days. Regardless of implantation interval, elements of Ti, O, C, and N were observed on the retrieved implants and that the thickness of the adsorbed film (mainly protein) was estimated to be about 2.5 nm. Small amounts of both Ca and P were also detected, whereby the Ca/P atomic ratios after 3 hours and 7 days were very small compared to that of hydroxyapatite. Furthermore, no correlation was found between the Ca and P distributions in the element maps. In conclusion, no calcium phosphate compounds were formed on the implant in vivo after 7 days. PMID:19496397

  20. Spatial And Temporal Variation In The Dissolved Trace Element Chemistry Of Chesapeake Bay Surface Waters

    NASA Astrophysics Data System (ADS)

    Dorval, E.; Hannigan, R.; Jones, C.

    2001-12-01

    Surface waters were collected from sea grass beds around the Chesapeake Bay of Virginia as well as from the mouths of the York, James, Potomac and Rappahannock rivers and Tangier and Smith islands. These sea grass beds represent the nursery habitats for a variety of sport fish including Spotted Sea Trout and Weakfish. Trace element ratios of fish otoliths record the unique chemistries of bodies of water in which the fish live. The data presented here represent the initial results of a "ground-truthing" investigation of the relationships between the water and otolith chemistry. Waters were collected bi-monthly (July through September) from 30 sites around the western and eastern shore of Chesapeake Bay including major tributaries and Tangier and Smith islands. Water was collected using trace metal clean procedures including filtration through a 0.45 uM filter and acidification in the field to pH < 2 with ultra-pure nitric acid. Dissolved trace element composition was measured by sector field ICP-MS. The trace element chemistry of samples show both spatial and temporal variation. Using discriminant analysis it is not possible to statistically classify samples to the respective zones (western shore, eastern shore or islands) but it is possible to separate samples from the Tangier and Smith island sites from the eastern and western shore sites. Elements that allow this classification include Ce and Th, which are found in higher concentration in the samples from the island sites than in the eastern and western shore samples. These relationships follow the trends observed in pH and dissolved oxygen likely related to a restricted flow regime between the islands and the eastern shore. Mg/Ca and Sr/Ca ratios are unique for the sea grass beds along the western shore and allow the distinction of beds located between the York and Rappahannock rivers from those between the Rappahannock and Potomac rivers. Sr and Ba concentrations are variable between sites along the eastern

  1. 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.

  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. 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

  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. An approach estimating bidirectional air-surface exchange for gaseous elemental mercury at AMNet sites

    NASA Astrophysics Data System (ADS)

    Wright, L. Paige; Zhang, Leiming

    2015-03-01

    The bidirectional air-surface exchange for gaseous elemental mercury (GEM) and existing measurements of the compensation points over a variety of canopy types are reviewed. Deposition and emission of GEM are dependent on several factors such as the type of canopy, temperature, season, atmospheric GEM concentrations, and meteorological conditions, with compensation points varying between 0.5 and 33 ng m-3. Emissions tend to increase from the spring to summer seasons, as the GEM accumulates in the foliage of the vegetation. A strong dependence on solar radiation has been observed, with higher emissions under light conditions. A bidirectional air-surface exchange flux model is proposed for estimating GEM fluxes at a two-hourly time resolution for the National Atmospheric Deposition Program's, Atmospheric Mercury Network (AMNet) sites. Compared to the unidirectional dry deposition model used in Zhang et al. (2012), two additional parameters, stomatal and soil emission potential, were needed in the bidirectional model and were chosen based on knowledge gained in the literature review and model sensitivity test results. Application of this bidirectional model to AMNet sites have produced annual net deposition fluxes comparable to those estimated in Zhang et al. (2012) at the majority of the sites. In this study, the net GEM dry deposition has been estimated separately for each dominant land use type surrounding each site, and this approach is also recommended for future calculations for easy application of the results to assessments of the mercury effects on various ecosystems.

  6. 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

  7. Reliable Support Design for Excavations in Brittle Rock Using a Global Response Surface Method

    NASA Astrophysics Data System (ADS)

    Langford, J. Connor; Diederichs, Mark S.

    2015-03-01

    Spalling damage can pose significant risks during the construction of underground excavations in brittle rock. While deterministic analyses have traditionally been used in the design of these structures, reliability-based design (RBD) methods provide a more rational approach to quantify spalling risk by directly incorporating input uncertainty into the design process and quantifying variable ground response. This paper presents a new RBD approach to evaluate the excavation response and support performance for a tunnel in brittle ground. Guidance for the selection of appropriate parameters for variable brittle materials is provided using a combination of the damage initiation and spalling limit method and theories of microcrack initiation. System performance is then evaluated using a proposed global response surface method (GRSM) coupled with the first-order reliability method, random sampling and finite element analysis. The proposed GRSM provides a computationally efficient way to evaluate the probability of failure for various limit states, allowing for the selection of appropriate design parameters such as minimum bolt length and required bolt capacity during early stages of design. To demonstrate the usefulness of this approach, a preliminary design option for a proposed deep geologic repository located in Canada was assessed. Numerical analyses were completed using finite element modeling to determine the depth of spalling around the excavation and support loads over the range of possible rock mass and in situ stress conditions. The results of these analyses were then used to assess support performance and make support recommendations.

  8. 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

  9. Altered response hierarchy and increased T-cell breadth upon HIV-1 conserved element DNA vaccination in macaques.

    PubMed

    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 p24(gag) 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 p55(gag) 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

  10. 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

  11. 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

  12. Surface radiation governs precipitation responses in transient and equilibrium climates

    NASA Astrophysics Data System (ADS)

    Sun, Shanshan; Moyer, Elisabeth

    2014-05-01

    Changes in radiative forcing are important not only for their impact on the Earth's temperature but also for their impact on the hydrological cycle. We show that model predictions of an amplified hydrological cycle under higher-CO2 conditions are well explained by changes in the surface energy budget: increased latent heat export largely balances increased downwelling longwave radiation, primarily due to increased humidity in a warmer atmosphere (see also Wild and Liepert 2010). We demonstrate that similar fundamental radiative adjustments govern global precipitation evolution across models, using twenty different GCMs in the Coupled Model Intercomparison Project phase 5 (CMIP5), purpose-run simulations with a fully-coupled GCM (CCSM3), and a simple one-column climate model (CliMT) with no cloud feedbacks but full representations of radiation, convection, turbulence, and surface ocean-atmosphere interaction. Physically understandable surface energy balance changes explain precipitation evolution in both equilibrium and transient climates (the well-documented 'fast' and 'slow' responses), in cases with different forcing agents (solar insolation and CO2), and in geo-engineering simulations where reduced shortwave forcing compensates for increased longwave opacity. We show that the enhancement in precipitation after an increase in radiative forcing is primarily due to the radiative effects of increased water vapor, which in turn produces the similarity in precipitation evolution in solar- and CO2-forced climates. We also show that differences in precipitation evolution between GCMs are due largely to differences in model shortwave feedbacks. The results of this study suggest that changes in the Earth's hydrological cycle under climate change can best be monitored and understood with surface measurements of longwave and shortwave fluxes, especially in the tropics and subtropics that account for the majority of the global moisture supply. References Wild, M. and B

  13. Identification and characterization of the retinoic acid response elements in the human RIG1 gene promoter

    SciTech Connect

    Jiang, S.-Y.; Wu, M.-S.; Chen, L.-M.; Hung, M.-W.; Lin, H.-E.; Chang, G.-G.; Chang, T.-C. . E-mail: tcchang@ndmctsgh.edu.tw

    2005-06-03

    The expression of retinoic acid-induced gene 1 (RIG1), a class II tumor suppressor gene, is induced in cells treated with retinoids. RIG1 has been shown to express ubiquitously and the increased expression of this gene appears to suppress cell proliferation. Recent studies also demonstrated that this gene may play an important role in cell differentiation and the progression of cancer. In spite of the remarkable regulatory role of this protein, the molecular mechanism of RIG1 expression induced by retinoids remains to be clarified. The present study was designed to study the molecular mechanism underlying the all-trans retinoic acid (atRA)-mediated induction of RIG1 gene expression. Polymerase chain reaction was used to generate a total of 10 luciferase constructs that contain various fragments of the RIG1 5'-genomic region. These constructs were then transfected into human gastric cancer SC-M1 and breast cancer T47D cells for transactivation analysis. atRA exhibited a significant induction in luciferase activity only through the -4910/-5509 fragment of the 5'-genomic region of RIG1 gene relative to the translation initiation site. Further analysis of this promoter fragment indicated that the primary atRA response region is located in between -5048 and -5403 of the RIG1 gene. Within this region, a direct repeat sequence with five nucleotide spacing, 5'-TGACCTctattTGCCCT-3' (DR5, -5243/-5259), and an inverted repeat sequence with six nucleotide spacing, 5'-AGGCCAtggtaaTGGCCT-3' (IR6, -5323/-5340), were identified. Deletion and mutation of the DR5, but not the IR6 element, abolished the atRA-mediated activity. Electrophoretic mobility shift assays with nuclear extract from atRA-treated cells indicated the binding of retinoic acid receptor (RAR) and retinoid X receptor (RXR) heterodimers specifically to this response element. In addition to the functional DR5, the region contains many other potential sequence elements that are required to maximize the at

  14. A finite element large deflection random response of a pipe containing fluid flow

    NASA Technical Reports Server (NTRS)

    Chiang, C. K.

    1991-01-01

    A finite element approach is developed for beam type pipes undergoing large deflections subjected to random loadings. The influence of fluid velocity on the random response is investigated. The root-mean-square (rms) deflections and frequencies for different sound spectrum level values are determined for pipes with both ends either simply supported or clamped. The required number of modes to achieve accurate rms deflections is studied. The prediction of fatigue life is then based on the maximum rms stress. This analytical investigation will help to broaden the basic understanding of the role of fluid flow within structures subjected to random excitations.

  15. Integration of growth factor signals at the c-fos serum response element.

    PubMed

    Price, M A; Hill, C; Treisman, R

    1996-04-29

    A transcription factor ternary complex composed of serum response factor (SRF) and a second factor, ternary complex factor (TCF), mediates the response of the c-fos Serum Response Element to growth factors and mitogens. In NIH3T3 fibroblasts, TCF binding is required for transcriptional activation by the SRE in response to activation of the Ras-Raf-ERK pathway. We compared the properties of three members of the TCF family, Elk-1, SAP-1 and SAP-2 (ERP/NET). Although all the proteins contain sequences required for ternary complex formation with SRF, only Elk-1 and SAP-1 appear to interact with the c-fos SRE efficiently in vivo. Each TCF contains a C-terminal activation domain capable of transcriptional activation in response to activation of the Ras-Raf-ERK pathway, and this is dependent on the integrity of S/T-P motifs conserved between all the TCF family members. In contrast, activation of the SRE by whole serum and the mitogenic phospholipid LPA requires SRF binding alone. Constitutively activated members of the Rho subfamily of Ras-like GTPases are also capable of inducing activation of the SRE in the absence of TCF; unlike activated Ras itself, these proteins do not activate the TCFs in NIH3T3 cells. At the SRE, SRF- and TCF-linked signalling pathways act synergistically to potentiate transcription. PMID:8735278

  16. 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.

  17. 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

  18. A novel hepatitis B virus (HBV) genetic element with Rev response element-like properties that is essential for expression of HBV gene products.

    PubMed Central

    Huang, J; Liang, T J

    1993-01-01

    Many viruses possess complex mechanisms involving multiple gene products and cis-regulatory elements in order to achieve a fine control of their gene expression at both transcriptional and posttranscriptional levels. Hepatitis B virus (HBV) and retroviruses share many structural and functional similarities. In this study, by genetic and biochemical analyses, we have demonstrated the existence of a novel genetic element within the HBV genome which is essential for high-level expression of viral gene products. This element is located 3' to the envelope coding region. We have shown that this genetic element is cis acting at the posttranscriptional level and that its function is exerted at the level of RNA processing as part of transcribed sequences. This RNA element is also functional in the context of a heterologous gene. Similar to the function of Rev-Rev response element interaction of human immunodeficiency virus type 1, this element appears to inhibit the splicing process and facilitate the transport and utilization of HBV transcripts. Images PMID:8246965

  19. Fabrication and evaluation of temperature responsive molecularly imprinted sorbents based on surface of yeast via surface-initiated AGET ATRP

    NASA Astrophysics Data System (ADS)

    Pan, Jianming; Hang, Hui; Li, Xiuxiu; Zhu, Wenjing; Meng, Minjia; Dai, Xiaohui; Dai, Jiangdong; Yan, Yongsheng

    2013-12-01

    Temperature responsive molecularly imprinted polymers (T-MIPs) were prepared based on the surface of yeast by electron transfer atom transfer radical polymerization (AGET ATRP). The as-prepared T-MIPs were charcterized by FT-IR, SEM, TGA and elemental analysis, which indicated that T-MIPs exhibited thermal stability and composed of temperature responsive imprinted layer. Then T-MIPs were evaluated as sorbents to selectively recognise and release cefalexin (CFX) molecules. The results suggested binding properties of T-MIPs were related to the testing temperature. The maximum adsorption capacity of T-MIPs at 303 K was 59.4 mg g-1, and the maximum release proportion for T-MIPs at 293 K in water for 24 h was 71.08%. The selective recognition experiments demonstrated high affinity and selectivity of T-MIPs towards CFX over competitive compounds, and the specific recognition of binding sites may be based on the distinct size, structure and functional group to the template molecules.

  20. 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

  1. [Sensory characterization of lupin pudding using surface response methodology].

    PubMed

    Villarroel, M; Biolley, E; Miranda, H; Wittig, E; Catalán, M

    1996-09-01

    Full fat sweet lupin flour (Lupinus albus c.v. Multolupa) with 39.6% protein and 13.0% lipid content, and carrageenan were used to incorporate them to commercial pudding formula with the specific purpose to prepare an optimized pudding for diabetic people. Using response surface methodology, several experimental pudding trails were prepared and sensorially assessed to optimize the variables that may influence the overall sensory quality of pudding meals. Different concentrations of lupin flour and carrageenan were tested simultaneously at three levels each parameter, requiring nine combinations to be analyzed for a panel of eleven trained judges. Appearance, aroma, taste, color, texture were tested to determine total sensory quality using a composite scoring test. It was concluded that appropriate concentration of lupin flour range from 7% to 11%, and carrageenan from 0.4% to 0.5% to be added to the pudding formulation. This result was confirmed by hedonic test of acceptability. PMID:9429627

  2. 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.

  3. 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

  4. 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

  5. Identification of a Novel Endoplasmic Reticulum Stress Response Element Regulated by XBP1*

    PubMed Central

    Misiewicz, Michael; Déry, Marc-André; Foveau, Bénédicte; Jodoin, Julie; Ruths, Derek; LeBlanc, Andréa C.

    2013-01-01

    Understanding the regulatory mechanisms mediating PRNP gene expression is highly relevant to elucidating normal cellular prion protein (PrP) function(s) and the transmissibility of prion protein neurodegenerative diseases. Here, luciferase reporter assays showed that an endoplasmic reticulum stress element (ERSE)-like element, CCAAT-N26-CCACG in the human PRNP promoter, is regulated by ER stress and X-box-binding protein 1 (XBP1) but not by activating transcription factor 6 α (ATF6α). Bioinformatics identified the ERSE-26 motif in 37 other human genes in the absence of canonical ERSE sites except for three genes. Several of these genes are associated with a synaptic function or are involved in oxidative stress. Brefeldin A, tunicamycin, and thapsigargin ER stressors induced gene expression of PRNP and four randomly chosen ERSE-26-containing genes, ERLEC1, GADD45B, SESN2, and SLC38A5, in primary human neuron cultures or in the breast carcinoma MCF-7 cell line, although the level of the response depends on the gene analyzed, the genetic background of the cells, the cell type, and the ER stressor. Overexpression of XBP1 increased, whereas siRNA knockdown of XBP1 considerably reduced, PRNP and ERLEC1 mRNA levels in MCF-7 cells. Taken together, these results identify a novel ER stress regulator, which implicates the ER stress response in previously unrecognized cellular functions. PMID:23737521

  6. 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

  7. Molecular cloning and expression of chicken carbohydrate response element binding protein and Max-like protein X gene homologues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbohydrate response element binding protein (ChREBP) and sterol regulatory element binding protein-1c (SREBP-1c) are transcription factors that are known to be key regulators of glucose metabolism and lipid synthesis in mammals. Since ChREBP and its co-activator Max-like protein X (Mlx) have not ...

  8. 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. PMID:19602457

  9. 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.

  10. Eye as a key element of conspecific image eliciting lateralized response in fish.

    PubMed

    Karenina, Karina A; Giljov, Andrey N; Malashichev, Yegor B

    2013-03-01

    Visual lateralization in different aspects of social behaviour has been found for numerous species of vertebrates ranging from fish to mammals. For inspection of a shoal mate, many fishes show a left eye-right hemisphere preference. Here, we tested the hypothesis that in fish, there is a key cue in the conspecific appearance, which elicits lateralized response to the whole image of the conspecific. In a series of eight experiments, we explored eye preferences in cryptic-coloured Amur sleeper, Perccottus glenii, fry. Fish displayed left-eye preferences at the population level for inspection of a group of conspecifics, their own mirror image, and a motionless flat model of a conspecific. In contrast, no population bias was found for scrutinizing an empty environment or a moving cylinder. When fry were showed a model of a conspecific in a lateral view with the eye displaced from the head to the tail, they again showed a significant preference for left-eye use. On the other hand, 'eyeless' conspecific model elicited no lateralized viewing in fry. Finally, the left-eye preference was revealed for scrutiny of the image of a conspecific eye alone. We argue that in Amur sleeper fry, eye is the element of the conspecific image, which can serve as a 'key' for the initiation of lateralized social response. This key element may serve as a trigger for the rapid recognition of conspecifics in the left eye-right hemisphere system. Possible causes and advantages of lateralized perception of social stimuli and their key elements are discussed in the context of current theories of brain lateralization. PMID:23111900

  11. Characterization of a retinoic acid responsive element isolated by whole genome PCR.

    PubMed Central

    Costa-Giomi, M P; Gaub, M P; Chambon, P; Abarzúa, P

    1992-01-01

    We have used whole PCR in an attempt to isolate novel retinoic acid (RA) responsive genes. We cloned several small genomic fragments from total human DNA containing putative retinoic acid responsive elements (RAREs) selected by direct binding to the retinoic acid receptor alpha (RAR alpha). We report here that an oligonucleotide containing a sequence from one of the cloned human DNA fragments, and referred to as alpha 1, functions as an authentic RARE. It is shown that both RAR alpha and RAR beta produced in Cos cells as well as in vitro translated RAR alpha bind directly and sequence-specifically to the alpha 1RARE. By mutational analysis it is demonstrated that the alpha 1RARE consists of an imperfect direct repeat of the estrogen- and thyroid hormone-related AGGTCA half-site motif separated by a 5 bp spacer. The orientation and spacing of the half-site repeats are shown to play a critical role in RAR recognition. When cloned upstream of a TK-Luc reporter, the alpha 1RARE is shown to confer responsiveness to RA in an orientation-independent fashion in F9 and CV-1 cells. The magnitude of the RA response mediated by the alpha 1RARE differed in these cell lines. Images PMID:1320257

  12. 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. PMID:23856495

  13. 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.

  14. Transcriptional induction of IFN-gamma-responsive genes is modulated by DNA surrounding the interferon stimulation response element.

    PubMed Central

    Strehlow, I; Decker, T

    1992-01-01

    The 9/27 and GBP mRNAs are both inducible by Interferon-gamma (IFN-gamma). The promoters of both genes contain an Interferon Stimulation Response Element (ISRE), but while the GBP gene is strongly induced transcriptionally by IFN-gamma the response of the 9/27 promoter is very weak. We investigated the molecular basis for this difference. The different IFN-gamma-responsiveness was found to have more than one reason. First, 9/27 promoter DNA was unable to bind the Gamma Interferon Activation Factor (GAF) with a single high affinity site. It efficiently competed for the association of the GAF with the GBP promoter but this competition was due to the presence of two low affinity sites, the ISRE and an ISRE-like sequence, suggesting that the GAS and ISRE, though both having clear preferences for specific proteins, may nevertheless share a certain degree of structural homology. Second, the 9/27 and GBP ISREs differed markedly in their affinities for regulatory proteins (ISGFs 1,2,3) and the GBP ISRE was more potent in mediating IFN-gamma-induced promoter activity in transient transfection. Third and most importantly, however, the strong difference between the IFN-gamma response of the two promoters was mainly due to the sequences surrounding the ISRE: the positive-acting GAS on one side and sequences with silencing properties 5' and 3' of the 9/27 ISRE on the other side. The data thus show mechanisms to both up- and down-regulate the activity of the ISRE. Images PMID:1508672

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Involvement of cyclic-nucleotide response element-binding family members in the radiation response of Ramos B lymphoma cells

    PubMed Central

    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

  3. 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

  4. 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.

  5. 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

  6. Platinum-group elements: quantification in collected exhaust fumes and studies of catalyst surfaces.

    PubMed

    Palacios, M A; Gómez, M M; Moldovan, M; Morrison, G; Rauch, S; Mcleod, C; Ma, R; Laserna, J; Lucena, P; Caroli, S; Alimonti, A; Petrucci, F; Bocca, B; Schramel, P; Lustig, S; Zischka, M; Wass, U; Stenbom, B; Luna, M; Saenz, J C; Santamaría, J; Torrens, J M

    2000-07-20

    Automotive catalytic converters, in which Pt, Pd and Rh (platinum-group elements; PGEs) are the active components for eliminating several noxious components from exhaust fumes, have become the main source of environmental urban pollution by PGEs. This work reports on the catalyst morphology through changes in catalyst surface by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and laser-induced breakdown spectrometry (LIBS) from fresh to aged catalytic converters. The distribution of these elements in the fresh catalysts analysed (Pt-Pd-Rh gasoline catalyst) is not uniform and occurs mainly in a longitudinal direction. This heterogeneity seems to be greater for Pt and Pd. PGEs released by the catalysts, fresh and aged 30,000 km, were studied in parallel. Whole raw exhaust fumes from four catalysts of three different types were also examined. Two of these were gasoline catalysts (Pt-Pd Rh and Pd-Rh) and the other two were diesel catalysts (Pt). Samples were collected following the 91,441 EUDC driving cycle for light-duty vehicle testing. The results show that at 0 km the samples collected first have the highest content of particulate PGEs and although the general tendency is for the release to decrease with increasing number of samples taken, exceptions are frequent. At 30,000 km the released PGEs in gasoline and diesel catalysts decreased significantly. For fresh gasoline catalysts the mean of the total amount released was approximately 100, 250 and 50 ng km(-1) for Pt, Pd and Rh, respectively. In diesel catalysts the Pt release varied in the range 400-800 ng km-1. After ageing the catalysts up to 30,000 km, the gasoline catalysts released amounts of Pt between 6 and 8 ng km(-1), Pd between 12 and 16 ng km(-1) and Rh between 3 and 12 ng km(-1). In diesel catalysts the Pt release varied in the range 108-150 ng km(-1). The soluble portion of PGEs in the HNO3 collector solution represented less than 5% of the total amount for fresh catalysts

  7. 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.

  8. 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.

  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. 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

  11. A search in the genome of Saccharomyces cerevisiae for genes regulated via stress response elements.

    PubMed

    Moskvina, E; Schüller, C; Maurer, C T; Mager, W H; Ruis, H

    1998-08-01

    Stress response elements (STREs, core consensus AG4 or C4T) have been demonstrated previously to occur in the upstream region of a number of genes responsive to induction by a variety of stress signals. This stress response is mediated by the homologous transcription factors Msn2p and Msn4p, which bind specifically to STREs. Double mutants (msn2 msn4) deficient in these transcription factors have been shown to be hypersensitive to severe stress conditions. To obtain a more representative overview of the set of yeast genes controlled via this regulon, a computer search of the Saccharomyces cerevisiae genome was carried out for genes, which, similar to most known STRE-controlled genes, exhibit at least two STREs in their upstream region. In addition to the great majority of genes previously known to be controlled via STREs, 69 open reading-frames were detected. Expression patterns of a set of these were examined by grid filter hybridization, and 14 genes were examined by Northern analysis. Comparison of the expression patterns of these genes demonstrates that they are all STRE-controlled although their detailed expression patterns differ considerably. PMID:9730283

  12. 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. PMID:25579914

  13. 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...

  14. CHEMICAL MAPPING OF ELEMENTAL SULFUR ON PYRITE AND ARSENOPYRITE SURFACES USING NEAR-INFRARED RAMAN IMAGING MICROSCOPY. (R826189)

    EPA Science Inventory

    Abstract

    Near-infrared Raman imaging microscopy (NIRIM) was used to produce chemical images of the distribution of elemental sulfur on oxidized pyrite and arsenopyrite surfaces. Analysis using Savitsky¯Golay filtering permits an unambiguous identificati...

  15. Detection response of elemental species in single particles using aerosol time-of-flight mass spectrometry

    SciTech Connect

    Silva, P.J.; Gross, D.S.; Gaelli, M.E.; Prather, K.A.

    1998-12-31

    The introduction of real-time particle mass spectrometry(RTSPMS) techniques creates a powerful tool for the study of particulate pollution on the single particle level. One such technique, aerosol time-of-flight mass spectrometry (ATOFMS) provides the aerodynamic size and chemical composition of individual particles. By combining data on size and composition, identification of individual particle classes in ambient outdoor samples is possible. Chemical composition is obtained by performing laser desorption ionization of individual particles using a Nd:YAG laser with a wavelength of 266 nm. The power of RTSPMS techniques is due to the ability to analyze the chemical composition of a single particle. The application of these techniques to analysis of ambient data has been limited however, because few studies have been performed to assess the ability of RTSPMS techniques to detect a wide range of compounds present in the atmosphere on a quantitative rather than qualitative level. It is known that various elemental species will respond differently to laser desorption mass spectrometric detection due to characteristic absorption cross-section and ionization potentials. In order to determine the capability and biases of RTSPMS techniques for detection of elemental species, a series of in-laboratory and ambient experiments has been performed using controlled conditions. Particles of known concentration have been produced from solution using an aerosol generator and analyzed using ATOFMS to determine responses of individual elements on a single particle level. In addition, side-by-side analyses with traditional sampling methods such as MOUDI impactors provide data to show how ATOFMS measurements correlate with federal reference methods.

  16. A finite element model of region-specific response for mild diffuse brain injury.

    PubMed

    Fijalkowski, Ronald J; Yoganandan, Narayan; Zhang, Jiangyue; Pintar, Frank A

    2009-11-01

    It is well known that rotational loading is responsible for a spectrum of diffuse brain injuries spanning from concussion to diffuse axonal trauma. Many experimental studies have been performed to understand the pathological and biomechanical factors associated with diffuse brain injuries. Finite element models have also been developed to correlate experimental findings with intrinsic variables such as strain. However, a paucity of studies exist examining the combined role of the strain-time parameter. Consequently, using the principles of finite element analysis, the present study introduced the concept of sustained maximum principal strain (SMPS) criterion and explored its potential applicability to diffuse brain injury. An algorithm was developed to determine if the principal strain in a finite element of the brain exceeded a specified magnitude over a specific time interval. The anatomical and geometrical details of the rat for the two-dimensional model were obtained from published data. Using material properties from literature and iterative techniques, the model was validated under three distinct rotational loading conditions indicative of non-injury, concussion, and diffuse axonal trauma. Validation results produced a set of material properties to define the model and were deemed appropriate to examine the role of sustained strain as an indicator of the mechanics of mild diffuse brain injury at the local level. Using a separate set of histological data obtained from graded mild diffuse brain injury experimental studies in rats, different formulations of SMPS criterion were evaluated. For the hippocampus and parietal cortex regions, 4-4 SMPS criterion was found to most closely match with the pattern of histological results. This was further verified by correlating the fractional areas to the time of unconsciousness for each animal group. Although not fully conclusive, these results are valuable in the understanding of diffuse brain injury pathologies

  17. Design optimization of a permanent magnet synchronous motor by the response surface methodology

    NASA Astrophysics Data System (ADS)

    Fujishima, Y.; Wakao, S.; Yamashita, A.; Katsuta, T.; Matsuoka, K.; Kondo, M.

    2002-05-01

    This article proposes an effective computational approach to design optimization of an outer-rotor type permanent magnet synchronous motor. As usual, because of the complicated rotor configuration and the complex magnetic saturation effects, it is difficult to design the lightweight permanent magnet synchronous motor structure that makes good use of reluctance torque within an acceptable CPU time. In this article, we adopt the finite element method as a magnetic field analysis method and the genetic algorithms as a search method. Furthermore, the response surface methodology, which enables us to evaluate the objective physical quantities in a much shorter time, is introduced into the above methods in the proposed approach. This optimization approach results in an overall increase in the optimization speed, that is, substantial CPU time reduction in comparison with the case of a conventional one. Some numerical results that demonstrate the validity of the proposed approach are also presented.

  18. Identification and Validation of a Putative Polycomb Responsive Element in the Human Genome

    PubMed Central

    Bengani, Hemant; Mendiratta, Shweta; Maini, Jayant; Vasanthi, Dasari; Sultana, Hina; Ghasemi, Mohsen; Ramachandran, Sowmya; Mishra, Rakesh K.; Brahmachari, Vani

    2013-01-01

    Epigenetic cellular memory mechanisms that involve polycomb and trithorax group of proteins are well conserved across metazoans. The cis-acting elements interacting with these proteins, however, are poorly understood in mammals. In a directed search we identified a potential polycomb responsive element with 25 repeats of YY1 binding motifthatwe designate PRE-PIK3C2B as it occurs in the first intron of human PIK3C2B gene. It down regulates reporter gene expression in HEK cells and the repression is dependent on polycomb group of proteins (PcG). We demonstrate that PRE-PIK3C2B interacts directly with YY1 in vitro and recruits PRC2 complex in vivo. The localization of PcG proteins including YY1 to PRE-PIK3C2B in HEK cells is decreased on knock-down of either YY1 or SUZ12. Endogenous PRE-PIK3C2B shows bivalent marking having H3K27me3 and H3K4me3 for repressed and active state respectively. In transgenic Drosophila, PRE-PIK3C2B down regulates mini-white expression, exhibits variegation and pairing sensitive silencing (PSS), which has not been previously demonstrated for mammalian PRE. Taken together, our results strongly suggest that PRE-PIK3C2B functions as a site of interaction for polycomb proteins. PMID:23805300

  19. Formation of a Polycomb-Domain in the Absence of Strong Polycomb Response Elements.

    PubMed

    De, Sandip; Mitra, Apratim; Cheng, Yuzhong; Pfeifer, Karl; Kassis, Judith A

    2016-07-01

    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

  20. 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

  1. Selective binding of the estrogen receptor to one strand of the estrogen responsive element.

    PubMed Central

    Mukherjee, R

    1993-01-01

    The human estrogen receptor (hER) activates gene transcription by binding to cognate palindromic sequences called estrogen responsive elements (ERE). I used gel retardation assays and oligonucleotides containing the ERE from the Xenopus vitellogenin gene to study the interaction of the hER with the ERE. I observed that the hER bound to double-stranded ERE and to the single strand of the ERE that had T in the center with nearly equal affinity, but not to the strand which had A in the center. Interchanging the two central nucleotides changed the strand specificity. Binding of the hER to a single strand is extremely sensitive to temperature. Initial recognition of one of the two strands of the ERE may be involved in the binding of the hER to the ERE. Images PMID:8332462

  2. 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.

  3. 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

  4. Small molecule screen for inhibitors of expression from canonical CREB response element-containing promoters

    PubMed Central

    Mitton, Bryan; Hsu, Katie; Dutta, Ritika; Tiu, Bruce C.; Cox, Nick; McLure, Kevin G.; Chae, Hee-Don; Smith, Mark; Eklund, Elizabeth A.; Solow-Cordero, David E.; Sakamoto, Kathleen M.

    2016-01-01

    The transcription factor CREB (cAMP Response Element Binding Protein) is an important determinant in the growth of Acute Myeloid Leukemia (AML) cells. CREB overexpression increases AML cell growth by driving the expression of key regulators of apoptosis and the cell cycle. Conversely, CREB knockdown inhibits proliferation and survival of AML cells but not normal hematopoietic cells. Thus, CREB represents a promising drug target for the treatment of AML, which carries a poor prognosis. In this study, we performed a high-throughput small molecule screen to identify compounds that disrupt CREB function in AML cells. We screened ∼114,000 candidate compounds from Stanford University's small molecule library, and identified 5 molecules that inhibit CREB function at micromolar concentrations, but are non-toxic to normal hematopoietic cells. This study suggests that targeting CREB function using small molecules could provide alternative approaches to treat AML. PMID:26840025

  5. Finite element modeling of stress distribution in intervertebral spacers of different surface geometries.

    PubMed

    Lee, Jae Hyup; Baek, Myong-Hyun; Kim, Young Eun; Seo, Jun-Hyuk; Song, Dong Ryul; Ryu, Hyun-Seung; Lee, Choon-Ki; Chang, Bong-Soon

    2013-11-01

    Intervertebral disc spacers using bioactive ceramics have been used to treat degenerative spinal disease. Tooth-shaped spacers are commonly used to prevent migration, but there is a possibility of fracture when inserted or after insertion. Intervertebral disc spacers with either an isosceles triangle-shaped tooth (T1) or a right triangle-shaped tooth (T2) were used as a control group. The design factors for the experimental group were modified to prevent fractures induced by stress concentration, and the surfaces of the spacers were designed as either an isosceles triangle-shaped valley (V1) or a right triangle-shaped valley (V2). Linear analysis using finite element model (FEM) was performed, and Von Mises stress distribution was calculated by applying 1000 N of uniformly distributed load. Samples of the V2 design were made with bioactive glass-ceramics (BGS-7) and evaluated for compressive strength, fatigue degree, and impact strength. Von Mises stress was highest at the first tooth from the posterior side for the control group and at the center for the experimental group. Compared with the control group, the experimental group showed 18.4% and 82.5% reduction (V1 vs. T1 and V2 vs. T2, respectively) in the maximum stress at the bottom of the valleys. The FEM analysis revealed that the V2 design had the most even load distribution. The V2 samples with bioactive glass-ceramics were evaluated for compressive strength, and all six samples were not fractured up to 24 000 N. However, the average impact strength was 19.42 kN, suggesting that momentary force caused damage at a lower load than compression with a steady speed. The BGS-7 intervertebral disc spacer with V2 design was not fractured during the fatigue test at maximum pressure of 8000 N, R ≥10, 5 Hz, and 5 million cycles. These data confirm that the BGS-7 spacer with the V2 design may be clinically applicable. Collectively, the modified surface geometry of the experimental group significantly lowered Von

  6. 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.

  7. New Constraints on Terrestrial Surface-Atmosphere Fluxes of Gaseous Elemental Mercury Using a Global Database.

    PubMed

    Agnan, Yannick; Le Dantec, Théo; Moore, Christopher W; Edwards, Grant C; Obrist, Daniel

    2016-01-19

    Despite 30 years of study, gaseous elemental mercury (Hg(0)) exchange magnitude and controls between terrestrial surfaces and the atmosphere still remain uncertain. We compiled data from 132 studies, including 1290 reported fluxes from more than 200,000 individual measurements, into a database to statistically examine flux magnitudes and controls. We found that fluxes were unevenly distributed, both spatially and temporally, with strong biases toward Hg-enriched sites, daytime and summertime measurements. Fluxes at Hg-enriched sites were positively correlated with substrate concentrations, but this was absent at background sites. Median fluxes over litter- and snow-covered soils were lower than over bare soils, and chamber measurements showed higher emission compared to micrometeorological measurements. Due to low spatial extent, estimated emissions from Hg-enriched areas (217 Mg·a(-1)) were lower than previous estimates. Globally, areas with enhanced atmospheric Hg(0) levels (particularly East Asia) showed an emerging importance of Hg(0) emissions accounting for half of the total global emissions estimated at 607 Mg·a(-1), although with a large uncertainty range (-513 to 1353 Mg·a(-1) [range of 37.5th and 62.5th percentiles]). The largest uncertainties in Hg(0) fluxes stem from forests (-513 to 1353 Mg·a(-1) [range of 37.5th and 62.5th percentiles]), largely driven by a shortage of whole-ecosystem fluxes and uncertain contributions of leaf-atmosphere exchanges, questioning to what degree ecosystems are net sinks or sources of atmospheric Hg(0). PMID:26599393

  8. Phorbol 12-myristate 13-acetate promotes nuclear translocation of hepatic steroid response element binding protein-2.

    PubMed

    Wong, Tsz Yan; Tan, Yan Qin; Lin, Shu-Mei; Leung, Lai K

    2016-06-01

    Sterol regulatory element-binding protein (SREBP)-2 is a pivotal transcriptional factor in cholesterol metabolism. Factors interfering with the proper functioning of SREBP-2 potentially alter plasma lipid profiles. Phorbol 12-myristate 13-acetate (PMA), which is a common protein kinase C (PKC) activator, was shown to promote the post-translational processing and nuclear translocation of SREBP-2 in hepatic cells in the current study. Following SREBP-2 translocation, the transcripts of its target genes HMGCR and LDLR were upregulated as demonstrated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Electrophoretic mobility shift assays (EMSA) also demonstrated an induced DNA-binding activity on the sterol response element (SRE) domain under PMA treatment. The increase of activated Srebp-2 without the concurrent induced mRNA expression was also observed in an animal model. As the expression of SREBP-2 was not increased by PMA, the activation of PKC was the focus of investigation. Specific PKC isozyme inhibition and overexpression supported that PKCβ was responsible for the promoting effect. Further studies showed that the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK), but not 5' adenosine monophosphate-activated protein kinase (AMPK), were the possible downstream signaling proteins of PKCβ. In conclusion, this study illustrated that PKCβ increased SREBP-2 nuclear translocation in a pathway mediated by MEK/ERK and JNK, rather than the one dictated by AMPK. These results revealed a novel signaling target of PKCβ in the liver cells. PMID:27032751

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. An iterative immersed finite element method for an electric potential interface problem based on given surface electric quantity

    NASA Astrophysics Data System (ADS)

    Cao, Yong; Chu, Yuchuan; He, Xiaoming; Lin, Tao

    2015-01-01

    Interface problems involving the non-homogeneous flux jump condition are critical for engineering designs in the magnetostatic/electrostatic field. In applications, such as plasma simulation, we often only know the total electric quantity on the surface of the object, not the charge density distribution on the surface which appears as the non-homogeneous flux jump condition in the usual interface problems considered in the literature for the magnetostatic/electrostatic field. Based on structured meshes independent of the interface, this article proposes an iterative method that employs both the immersed finite element (IFE) method with non-homogeneous flux jump conditions and the regular finite element method with ghost nodes introduced in the object to solve the 2D interface problem for the potential field according to the given total electric quantity on the surface of the object. Numerical experiments are provided to illustrate the accuracy and efficiency of the proposed method.

  15. 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

  16. 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

  17. 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

  18. 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. PMID:27081794

  19. 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. PMID:21494829

  20. Identification of two novel shear stress responsive elements in rat angiotensin I converting enzyme promoter.

    PubMed

    Miyakawa, Ayumi Aurea; de Lourdes Junqueira, Maria; Krieger, José Eduardo

    2004-04-13

    Mechanical forces contribute to maintenance of cardiovascular homeostasis via the control of release and production of vasoactive substances. We demonstrated previously that shear stress decreases rat ACE activity and expression. Using a reporter gene approach and mutagenesis, we show now that the classic shear stress responsive element or SSRE (GAGACC) contained within 1,274 bp of this promoter is not functional in response to shear stress (15 dyn/cm2, 18 h) [for the wild-type ACE promoter (WLuc), static control (C) = 107 +/- 6.5%, shear stress (SS) = 65.9 +/- 9.4%, n = 8; for the promoter with the classic SSRE mutated (WSS-mut), C = 100 +/- 8.2%, SS = 60.2 +/- 5.2%, n = 10, respectively]. Analysis of progressive deletion mutants unraveled a 57-bp fragment, position -251 to -195, from the transcription start site, containing functional SSRE (for WLuc, C = 107 +/- 6.5%, SS = 65.9 +/- 9.4%, n = 8; for 378, C = 100 +/- 6.4%, SS = 60.4 +/- 4.3%, n = 11; for 251, C = 99.7 +/- 2.6%, SS = 63.2 +/- 5.5%, n = 7; for 194, C = 104.6 +/- 8.1%, SS = 92.4 +/- 6.9%, n = 9). This fragment responded to shear stress even in the context of a heterologous promoter. Finally, functional analysis of mutated candidate regulatory elements identified by gel shift, DNase I footprint, and conservation of aligned sequences revealed that only the double mutant (Barbie/GAGA-mut) but not isolated disruption of the Barbie (WBarbie-mut) or the GAGA (WGAGA-mut) prevented the shear-stress-induced response (for Barbie/GAGA-mut, C = 97.9 +/- 5%, SS = 99.4 +/- 7.2%, n = 6; for WBarbie-mut, C = 106.1 +/- 8.6%, SS = 65.9 +/- 9.4%, n = 6; for WGAGA-mut, C = 100.1 +/- 2.9%, SS = 66.7 +/- 1.6, n = 6;). Taken together, these data provide direct evidence for the new role of Barbie and GAGA boxes in mediating the shear-stress-induced downregulation of rat ACE expression and demonstrate that the classic SSRE (GAGACC) is not functional under the experimental conditions tested. PMID:14872008

  1. 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

  2. Inhibition of transferrin receptor 1 transcription by a cell density response element

    PubMed Central

    2005-01-01

    TfR1 (transferrin receptor 1) mediates the uptake of transferrin-bound iron and thereby plays a critical role in cellular iron metabolism. Its expression is coupled to cell proliferation/differentiation and controlled in response to iron levels and other signals by transcriptional and post-transcriptional mechanisms. It is well established that TfR1 levels decline when cultured cells reach a high density and in the present study we have investigated the underlying mechanisms. Consistent with previous findings, we demonstrate that TfR1 expression is attenuated in a cell-density-dependent manner in human lung cancer H1299 cells and in murine B6 fibroblasts as the result of a marked decrease in mRNA content. This response is not associated with alterations in the RNA-binding activity of iron regulatory proteins that are indicative of a transcriptional mechanism. Reporter assays reveal that the human TfR1 promoters contains sequences mediating cell-density-dependent transcriptional inhibition. Mapping of the human and mouse TfR1 promoters identified a conserved hexa-nucleotide 5′-GAGGGC-3′ motif with notable sequence similarity to a previously described element within the IGF-2 (insulin-like growth factor-2) promoter. We show that this motif is necessary for the formation of specific complexes with nuclear extracts and for cell-density-dependent regulation in reporter gene assays. Thus the TfR1 promoter contains a functional ‘cell density response element’ (CDRE). PMID:16092918

  3. Effects of trace element supplementation on the inflammatory response in a rabbit model of major trauma.

    PubMed

    Yuan, Wan-an; Yu, Xiao-jun; Liu, Fu-Qi; Wang, Hai-peng; Wang, Dian; Lai, Xiao-ping

    2010-01-01

    Patients with a severe trauma exhibit a strong oxidative stress, an intense inflammatory response, and long-lasting hypermetabolism, all of which are proportional to the severity of injury. In this study, we investigated the impact of trace element (TE) supplementation on the inflammatory response in an animal model of major trauma. New Zealand White rabbits were randomly assigned as a control group (n=5) and an experimental group (n=70) that, after receiving a major trauma, was subdivided into Trauma-Control (n=35) and Trauma-TE (n=35) groups. Systemic inflammatory response syndrome (SIRS) was observed in 40 out of 70 rabbits with a trauma, with a higher incidence in the Trauma-Control group (88.6%; 31/35) than the Trauma-TE group (28.6%; 10/35) (p<0.01). The mortality rate was significantly different between the Trauma-Control and the Trauma-TE groups; (34% vs. 8%; p<0.01). There were significant post-trauma alterations in the levels of (1) serum and spleen zinc (Zn), copper (Cu), selenium (Se), and manganese (Mn), (2) serum AST and ALT, (3) serum interleukin-6/10, and (4) nuclear factor kappa binding (NF-kappaB) activity and the expression. TE supplementation: (1) improved blood urea nitrogen (BUN), and creatinine (Cr) levels, (2) stabilized IL-6/10 production, (3) decreased NF-kappaB p(65) production. Appropriate TE supplementation can improve the TE status, mitigate SIRS, and reduce the mortality due to multiple organ dysfunction syndromes (MODS)/multiple organ failure (MOF) after major trauma. PMID:20122578

  4. 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.

  5. Elements of the Chicxulub Impact Structure as revealed in SRTM and surface GPS topographic data

    NASA Astrophysics Data System (ADS)

    Kobrick, M.; Kinsland, G. L.; Sanchez, G.; Cardador, M. H.

    2003-04-01

    Pope et al have utilized elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxu-lub Impact Structure is a roughly semi-circular, low-relief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact which possibly led to the development of these features. Kinsland et al presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Shaded relief images from recently acquired SRTM elevation data clearly show the circular depression of the crater and the moat/cenote ring. In addition we can readily identify Inner trough 1, Inner trough 2 and Outer trough as defined by Pope et al. The agreement between the topographic maps of Pope et al, Kinsland et al and SRTM data are remarkable considering that the distribution and types of data in the sets are so different. We also have ground topographic data collected with a special "autonomous differ-ential GPS" system during summer 2002. Profiles from these data generally agree with both the gravity data based topographic maps and profiles extracted from the SRTM data. Preliminary analyses of our new data, SRTM and GPS, have uncovered features not previously recognized: 1) as shown by the GPS data the moat/cenote ring consists of two distinct depressions separated by about 10 km...perhaps separate ring faults, 2) in the SRTM data over the southern part of the crater and on southward for perhaps 20 km beyond the moat/ cenote ring there exists a pattern, as yet unexplained, of roughly concentric topographic features whose center lies at about 21deg 40min N and 89deg 25min W, about 50km NNE of the moat/cenote ring center. The corroboration and better definition of the previously recognized topographic features yielded by the two new forms of data strengthens the cases for these fea-tures and for their relevance to the underlying

  6. Overview of the surface architecture and elements common to a wide range of Lunar and Mars missions

    NASA Technical Reports Server (NTRS)

    Connolly, John F.; Toups, Larry D.

    1990-01-01

    NASA has studied future missions to the moon and Mars since the 1960's, and most recently during the studies for the Space Exploration Initiative chartered by President Bush. With these most recent studies, the Lunar and Mars Exploration Program Office is looking at a number of possible options for the human exploration of the solar system. Objectives of these options include science and exploration, testing and learning centers, local planetary resource development, and self sufficient bases. To meet the objectives of any particular mission, efforts have focused primarily in three areas: (1) space transportation vehicles, (2) the associated space infrastructure to support these vehicles, and (3) the necessary infrastructure on the planet surface to carry out the mission objectives. This paper looks at work done by the Planet Surface Systems Office at JSC in the third area, and presents an overview of the approach to determining appropriate equipment and elements of the surface infrastructure needed for these mission alternatives. It describes the process of deriving appropriate surface architectures with consideration of mission objectives leading to system concepts, designation of elements and element placement.

  7. Adsorption of trace elements on pyrite surfaces in sulfidic mine tailings from Kristineberg (Sweden) a few years after remediation.

    PubMed

    Müller, Barbara; Axelsson, Mikael D; Ohlander, Björn

    2002-10-21

    Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the elemental composition of the surface and interior layers of pyrite grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The pyrite grains were collected from oxidized and unoxidized zones within the tailings. The aim of this study was to assess the role of pyrite surfaces as sites for the attenuation of solutes from the mine-tailings porewater. The normalized intensities of Cu, Zn, Ag, Sb, Ce, Pb and Bi are highest at the surface of each grain (within the surface layer drilled by the LA) and decrease towards the interior. The surface adsorption of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Copper exhibits a distinct concentration peak at the surface of the pyrite grains below the pre-remediation oxidation front. Silver, Sb, Bi, As and Au are preferably adsorbed within the uppermost layer of the oxidized zone in the tailings, where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was accomplished using an external calibration against an in-house pyrite standard. PMID:12449325

  8. The Yeast Anaerobic Response Element AR1b Regulates Aerobic Antifungal Drug-dependent Sterol Gene Expression*

    PubMed Central

    Gallo-Ebert, Christina; Donigan, Melissa; Liu, Hsing-Yin; Pascual, Florencia; Manners, Melissa; Pandya, Devanshi; Swanson, Robert; Gallagher, Denise; Chen, WeiWei; Carman, George M.; Nickels, Joseph T.

    2013-01-01

    Saccharomyces cerevisiae ergosterol biosynthesis, like cholesterol biosynthesis in mammals, is regulated at the transcriptional level by a sterol feedback mechanism. Yeast studies defined a 7-bp consensus sterol-response element (SRE) common to genes involved in sterol biosynthesis and two transcription factors, Upc2 and Ecm22, which direct transcription of sterol biosynthetic genes. The 7-bp consensus SRE is identical to the anaerobic response element, AR1c. Data indicate that Upc2 and Ecm22 function through binding to this SRE site. We now show that it is two novel anaerobic AR1b elements in the UPC2 promoter that direct global ERG gene expression in response to a block in de novo ergosterol biosynthesis, brought about by antifungal drug treatment. The AR1b elements are absolutely required for auto-induction of UPC2 gene expression and protein and require Upc2 and Ecm22 for function. We further demonstrate the direct binding of recombinant expressed S. cerevisiae ScUpc2 and pathogenic Candida albicans CaUpc2 and Candida glabrata CgUpc2 to AR1b and SRE/AR1c elements. Recombinant endogenous promoter studies show that the UPC2 anaerobic AR1b elements act in trans to regulate ergosterol gene expression. Our results indicate that Upc2 must occupy UPC2 AR1b elements in order for ERG gene expression induction to take place. Thus, the two UPC2-AR1b elements drive expression of all ERG genes necessary for maintaining normal antifungal susceptibility, as wild type cells lacking these elements have increased susceptibility to azole antifungal drugs. Therefore, targeting these specific sites for antifungal therapy represents a novel approach to treat systemic fungal infections. PMID:24163365

  9. Shape factors for elements of the infiltration profile in surface irrigation:Generic approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Advanced mathematical models of surface irrigation are based on the equations of motion applied to a series of cells comprising the surface stream and an infiltration profile. In the simulation, a mass balance must be preserved amongst the inflow, surface stream, infiltrated profile, and runoff vol...

  10. Probing the Elastic-Plastic, Time-Dependant Response of Test Fasteners using Finite Element Analysis (FEA)

    SciTech Connect

    ML Renauld; H Lien

    2004-12-13

    The evolution of global and local stress/strain conditions in test fasteners under test conditions is investigated using elastic-plastic, time-dependent finite element analyses (FEA). For elastic-plastic response, tensile data from multiple specimens, material heats and test temperatures are integrated into a single, normalized flow curve from which temperature dependency is extracted. A primary creep model is calibrated with specimen- and fastener-based thermal relaxation data generated under a range of times, temperatures, stress levels and environments. These material inputs are used in analytical simulations of experimental test conditions for several types of fasteners. These fastener models are constructed with automated routines and contact conditions prescribed at all potentially mating surfaces. Thermal or mechanical room temperature pre-loading, as appropriate for a given fastener, is followed by a temperature ramp and a dwell time at constant temperature. While the amount of thermal stress relaxation is limited for the conditions modeled, local stress states are highly dependent upon geometry (thread root radius, for example), pre-loading history and thermal expansion differences between the test fastener and test fixture. Benefits of this FE approach over an elastic methodology for stress calculation will be illustrated with correlations of Stress Corrosion Cracking (SCC) initiation time and crack orientations in stress concentrations.

  11. ECOLOGICAL RESPONSE SURFACES FOR NORTH AMERICAN BOREAL TREE SPECIES AND THEIR USE IN FOREST CLASSIFICATION

    EPA Science Inventory

    Empirical ecological response surfaces were derived for eight dominant tree species in the boreal forest region of Canada. tepwise logistic regression was used to model species dominance as a response to five climatic predictor variables. he predictor variables (annual snowfall, ...

  12. 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

  13. Influence of push element geometry on the capture efficiency of push-pull ventilation systems in surface treatment tanks.

    PubMed

    Marzal, F; Gonzalez, E; Minana, A; Baeza, A

    2002-06-01

    A full-scale installation which simulates a surface treatment tank provided with a push-pull ventilation system has been designed. This study examines the influence of the geometry of the push element on the capture efficiency of the system. It is observed that: (i) capture efficiency increases with the number of holes because of the continuous curtain formed, the size of the holes having no significant effect within the range studied (5-20 mm diameter); (ii) the push element is best supported on the tank wall so that no air from outside penetrates below the emitting jets because in this way the impact of the curtain on the tank occurs earlier and losses are less; (iii) the best results are obtained when the holes are directed downwards towards the tank surface at an angle of between 22 and 45 degrees. PMID:12176707

  14. Communications: Adsorption of element 112 on the gold surface: Many-body wave function versus density functional theory

    NASA Astrophysics Data System (ADS)

    Zaitsevskii, Andréi; van Wüllen, Christoph; Titov, Anatoly V.

    2010-02-01

    The applicability of the relativistic density functional theory (RDFT) with conventional generalized gradient and hybrid exchange-correlation functionals to the description of the interactions of element 112 (Cn) and its lighter homolog Hg with a gold surface is assessed. The comparison of Cn-Au (Hg-Au) bond properties for two simple models of adsorption complexes on Au(111) surface obtained by RDFT and accurate many-body calculations indicates a strong underestimation of binding energies by conventional RDFT schemes. This effect provides a possible explanation of the discrepancies between the RDFT-based theoretical and experimental data concerning the thermochromatographic registration of the α-decay chain element 114→Cn.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Unit cell finite element modelling for ultrasonic scattering from periodic surfaces

    NASA Astrophysics Data System (ADS)

    Choi, W.; Skelton, E.; Lowe, M. J. S.; Craster, R.

    2013-01-01

    Ultrasound wave scattering from the rough surfaces of defects is an important consideration for the qualification of safety-critical inspections because some species of fabrication and service-induced defects are rough. Whereas the surfaces of flat defects only reflect specularly, an incident wave reflects over a range of angles when the surface is rough. This affects the inspection performance because the coefficient of the specular reflection is reduced, while the detection of reflections at other angles becomes possible. An infinite periodic surface is a simple form of rough surface, which has been well investigated since Rayleigh, and can be useful to provide general insight into the nature of the wave scattering. Furthermore, in the context of scattering from cracks, the study of an infinite surface enables examination of the reflections from the surface and behavior at the surface without the presence of the crack tip diffraction fields. In this paper, an infinite periodic surface is modelled by a unit cell FE model with cyclic symmetric boundary conditions, allowing the model to be small, and elastic wave scattering from the surface is simulated in the time domain. This cell model is demonstrated using the commercial FE package ABAQUS and examples of the scattered wave results are compared with large FE model results.

  20. Activation of antioxidant response element (ARE)-dependent genes by roasted coffee extracts.

    PubMed

    Yazheng, Liu; Kitts, David D

    2012-09-01

    Coffee beans contain numerous bioactive components that exhibit antioxidant capacity when assessed using both chemical, cell free, and biological, cell-based model systems. However, the mechanisms underlying the antioxidant effects of coffee in biological systems are not totally understood and in some cases vary considerably from results obtained with simpler in vitro chemical assays. In the present study, the physicochemical characteristics and antioxidant activity of roasted and non-roasted coffee extracts were investigated in both cell free (ORAC(FL)) and cell-based systems. A profile of antioxidant gene expression in cultured human colon adenocarcinoma Caco-2 cells treated with both roasted and non-roasted coffee extracts, respectively, was investigated using Real-Time polymerase chain reaction (PCR) array technology. Results demonstrated that the mechanisms of the antioxidant activity associated with coffee constituents assessed by the ORAC(FL) assay were different to those observed using an intracellular oxidation assay with Caco-2 cells. Moreover, roasted coffee (both light and dark roasted) extracts produced both increased- and decreased-expressions of numerous genes that are involved in the management of oxidative stress via the antioxidant defence system. The selective and specific positive induction of antioxidant response element (ARE)-dependent genes, including gastrointestinal glutathione peroxidase (GPX2), sulfiredoxin (SRXN1), thioredoxin reductase 1 (TXNRD1), peroxiredoxin 1 (PRDX1), peroxiredoxin 4 (PDRX4) and peroxiredoxin 6 (PDRX6) were identified with the activation of the endogenous antioxidant defence system in Caco-2 cells. PMID:22699814

  1. Structural basis for targeting the chromatin repressor Sfmbt to Polycomb response elements

    PubMed Central

    Alfieri, Claudio; Gambetta, Maria Cristina; Matos, Raquel; Glatt, Sebastian; Sehr, Peter; Fraterman, Sven; Wilm, Matthias; Müller, Jürg; Müller, Christoph W.

    2013-01-01

    Polycomb group (PcG) protein complexes repress developmental regulator genes by modifying their chromatin. How different PcG proteins assemble into complexes and are recruited to their target genes is poorly understood. Here, we report the crystal structure of the core of the Drosophila PcG protein complex Pleiohomeotic (Pho)-repressive complex (PhoRC), which contains the Polycomb response element (PRE)-binding protein Pho and Sfmbt. The spacer region of Pho, separated from the DNA-binding domain by a long flexible linker, forms a tight complex with the four malignant brain tumor (4MBT) domain of Sfmbt. The highly conserved spacer region of the human Pho ortholog YY1 binds three of the four human 4MBT domain proteins in an analogous manner but with lower affinity. Comparison of the Drosophila Pho:Sfmbt and human YY1:MBTD1 complex structures provides a molecular explanation for the lower affinity of YY1 for human 4MBT domain proteins. Structure-guided mutations that disrupt the interaction between Pho and Sfmbt abolish formation of a ternary Sfmbt:Pho:DNA complex in vitro and repression of developmental regulator genes in Drosophila. PRE tethering of Sfmbt by Pho is therefore essential for Polycomb repression in Drosophila. Our results support a model where DNA tethering of Sfmbt by Pho and multivalent interactions of Sfmbt with histone modifications and other PcG proteins create a hub for PcG protein complex assembly at PREs. PMID:24186981

  2. Cyclic AMP-Responsive Element Modulator α Polymorphisms Are Potential Genetic Risks for Systemic Lupus Erythematosus

    PubMed Central

    Guo, Qian; Chen, Xuyong; Du, Yan; Guo, Jianping; Su, Yin

    2015-01-01

    To investigate whether the cyclic AMP-responsive element modulator α (CREMα) polymorphisms are novel susceptibility factors for systemic lupus erythematosus (SLE), four tag SNPs, rs1057108, rs2295415, rs11592925, and rs1148247, were genotyped in 889 SLE cases and 825 healthy controls. Association analyses were performed on whole dataset or clinical/serologic subsets. Association statistics were calculated by age and sex adjusted logistic regression. The G allele frequencies of rs2295415 and rs1057108 were increased in SLE patients, compared with healthy controls (rs2295415: 21.2% versus 17.8%, OR 1.244, P = 0.019; rs1057108: 30.8% versus 27.7%, OR 1.165, P = 0.049). The haplotype constituted by the two risk alleles “G-G” from rs1057108 and rs2295415 displayed strong association with SLE susceptibility (OR 1.454, P = 0.00056). Following stratification by clinical/serologic features, a suggestive association was observed between rs2295415 and anti-Sm antibodies-positive SLE (OR 1.382, P = 0.044). Interestingly, a potential protective effect of rs2295415 was observed for SLE patients with renal disorder (OR 0.745, P = 0.032). Our data provide first evidence that CREMα SNPs rs2295415 and rs1057108 maybe novel genetic susceptibility factors for SLE. SNP rs2295415 appears to confer higher risk to develop anti-Sm antibodies-positive SLE and may play a protective role against lupus nephritis. PMID:26601115

  3. 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

  4. Identification and characterization of DNA sequences that prevent glucocorticoid receptor binding to nearby response elements.

    PubMed

    Telorac, Jonas; Prykhozhij, Sergey V; Schöne, Stefanie; Meierhofer, David; Sauer, Sascha; Thomas-Chollier, Morgane; Meijsing, Sebastiaan H

    2016-07-27

    Out of the myriad of potential DNA binding sites of the glucocorticoid receptor (GR) found in the human genome, only a cell-type specific minority is actually bound, indicating that the presence of a recognition sequence alone is insufficient to specify where GR binds. Cooperative interactions with other transcription factors (TFs) are known to contribute to binding specificity. Here, we reasoned that sequence signals preventing GR recruitment to certain loci provide an alternative means to confer specificity. Motif analyses uncovered candidate Negative Regulatory Sequences (NRSs) that interfere with genomic GR binding. Subsequent functional analyses demonstrated that NRSs indeed prevent GR binding to nearby response elements. We show that NRS activity is conserved across species, found in most tissues and that they also interfere with the genomic binding of other TFs. Interestingly, the effects of NRSs appear not to be a simple consequence of changes in chromatin accessibility. Instead, we find that NRSs interact with proteins found at sub-nuclear structures called paraspeckles and that these proteins might mediate the repressive effects of NRSs. Together, our studies suggest that the joint influence of positive and negative sequence signals partition the genome into regions where GR can bind and those where it cannot. PMID:27016732

  5. 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.

  6. p53 dynamics upon response element recognition explored by molecular simulations

    PubMed Central

    Terakawa, Tsuyoshi; Takada, Shoji

    2015-01-01

    p53 is a representative transcription factor that activates multiple target genes. To realize stimulus-dependent specificities, p53 has to recognize targets with structural variety, of which molecular mechanisms are largely unknown. Here, we conducted a series of long-time scale (totally more than 100-ms) coarse-grained molecular dynamics simulations, uncovering structure and dynamics of full-length p53 tetramer that recognizes its response element (RE). We obtained structures of a full-length p53 tetramer that binds to the RE, which is strikingly different from the structure of p53 at search. These structures are not only consistent with previous low-resolution or partial structural information, but also give access to previously unreachable detail, such as the preferential distribution of intrinsically disordered regions, the contacts between core domains, the DNA bending, and the connectivity of linker regions. We also explored how the RE variation affects the structure of the p53-RE complex. Further analysis of simulation trajectories revealed how p53 finds out the RE and how post-translational modifications affect the search mechanism. PMID:26596470

  7. 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.

  8. Killing of Brain Tumor Cells by Hypoxia-Responsive Element Mediated Expression of BAX1

    PubMed Central

    Ruan, Hangjun; Wang, Jingli; Hu, Lily; Lin, Ching-Shwun; Lamborn, Kathleen R; Deen, Dennis F

    1999-01-01

    Abstract The presence of radioresistant hypoxic cells in human brain tumors limits the overall effectiveness of conventional fractionated radiation therapy. Tumor-specific therapies that target hypoxic cells are clearly needed. We have investigated the expression of suicide genes under hypoxia by a hypoxia-responsive element (HRE), which can be activated through hypoxia-inducible factor-1 (HIF-1). We transfected plasmids containing multiple copies of HRE into U-87 MG and U-251 MG-NCI human brain tumor cells and tested their ability to induce LacZ gene expression under anoxia. Gene expression under anoxia versus oxia was increased about 12-fold for U-87 MG cells and about fourfold for U-251 MG-NCI cells. At intermediate hypoxic conditions, increased LacZ gene expression in U-87 MG cells was induced by the plasmid that contained three HREs, but not by the plasmid with two HREs. Lastly, when we placed a suicide gene BAX under the control of HREs, cells transfected with the BAX plasmids were preferentially killed through apoptosis under anoxia. Our studies demonstrate that HRE-regulated gene expression is active in brain tumor cells, and that the amount of increased gene expression obtained is dependent on the cell line, the HRE copy number, and the degree of hypoxia. PMID:10933058

  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. Bisphenol A activates the Nrf1/2-antioxidant response element pathway in HEK 293 cells.

    PubMed

    Chepelev, Nikolai L; Enikanolaiye, Mutiat I; Chepelev, Leonid L; Almohaisen, Abdulrahman; Chen, Qixuan; Scoggan, Kylie A; Coughlan, Melanie C; Cao, Xu-Liang; Jin, Xiaolei; Willmore, William G

    2013-03-18

    Bisphenol A (BPA) is used in the production of polycarbonate plastics and epoxy resins for baby bottles, liners of canned food, and many other consumer products. Previously, BPA has been shown to reduce the activity of several antioxidant enzymes, which may contribute to oxidative stress. However, the underlying mechanism of the BPA-mediated effect upon antioxidant enzyme activity is unknown. Antioxidant and phase II metabolizing enzymes protect cells from oxidative stress and are transcriptionally activated by Nrf1 and Nrf2 factors through their cis-regulatory antioxidant response elements (AREs). In this work, we have assessed the effect of BPA on the Nrf1/2-ARE pathway in cultured human embryonic kidney (HEK) 293 cells. Surprisingly, glutathione and reactive oxygen species (ROS) assays revealed that BPA application created a more reduced intracellular environment in cultured HEK 293 cells. Furthermore, BPA increased the transactivation activity of ectopic Nrf1 and Nrf2 and increased the expression of ARE-target genes ho-1 and nqo1 at high (100-200 μM) BPA concentrations only. Our study suggests that BPA activates the Nrf1/2-ARE pathway at high (>10 μM) micromolar concentrations. PMID:23360430

  11. Characterization of human glucocorticoid receptor complexes formed with DNA fragments containing or lacking glucocorticoid response elements

    SciTech Connect

    Tully, D.B.; Cidlowski, J.A. )

    1989-03-07

    Sucrose density gradient shift assays were used to study the interactions of human glucocorticoid receptors (GR) with small DNA fragments either containing or lacking glucocorticoid response element (GRE) DNA consensus sequences. When crude cytoplasmic extracts containing ({sup 3}H)triamcinolone acetonide (({sup 3}H)TA) labeled GR were incubated with unlabeled DNA under conditions of DNA excess, a GRE-containing DNA fragment obtained from the 5' long terminal repeat of mouse mammary tumor virus (MMTV LTR) formed a stable 12-16S complex with activated, but not nonactivated, ({sup 3}H)TA receptor. By contrast, if the cytosols were treated with calf thymus DNA-cellulose to deplete non-GR-DNA-binding proteins prior to heat activation, a smaller 7-10S complex was formed with the MMTV LTR DNA fragment. Activated ({sup 3}H)TA receptor from DNA-cellulose pretreated cytosols also interacted with two similarly sized fragments from pBR322 DNA. Stability of the complexes formed between GR and these three DNA fragments was strongly affected by even moderate alterations in either the salt concentration or the pH of the gradient buffer. Under all conditions tested, the complex formed with the MMTV LTR DNA fragment was more stable than the complexes formed with either of the pBR322 DNA fragments. Together these observations indicate that the formation of stable complexes between activated GR and isolated DNA fragments requires the presence of GRE consensus sequences in the DNA.

  12. Divergent Binding and Transactivation by Two Related Steroid Receptors at the Same Response Element.

    PubMed

    Tesikova, Martina; Dezitter, Xavier; Nenseth, Hatice Z; Klokk, Tove I; Mueller, Florian; Hager, Gordon L; Saatcioglu, Fahri

    2016-05-27

    Transcription factor (TF) recruitment to chromatin is central to activation of transcription. TF-chromatin interactions are highly dynamic, which are evaluated by recovery half time (t1/2) in seconds, determined by fluorescence recovery experiments in living cells, and chromatin immunoprecipitation (ChIP) analysis, measured in minutes. These two states are related: the larger the t1/2, the longer the ChIP occupancy resulting in increased transcription. Here we present data showing that this relationship does not always hold. We found that histone deacetylase inhibitors (HDACis) significantly increased t1/2 of green fluorescent protein (GFP) fused androgen receptor (AR) on a tandem array of positive hormone response elements (HREs) in chromatin. This resulted in increased ChIP signal of GFP-AR. Unexpectedly, however, transcription was inhibited. In contrast, the GFP-fused glucocorticoid receptor (GR), acting through the same HREs, displayed a profile consistent with current models. We provide evidence that these differences are mediated, at least in part, by HDACs. Our results provide insight into TF action in living cells and show that very closely related TFs may trigger significantly divergent outcomes at the same REs. PMID:27056330

  13. Activity of a Py-Im Polyamide Targeted to the Estrogen Response Element

    PubMed Central

    Nickols, Nicholas G.; Szablowski, Jerzy O.; Hargrove, Amanda E.; Li, Benjamin C.; Raskatov, Jevgenij A.; Dervan, Peter B.

    2013-01-01

    Pyrrole-imidazole (Py-Im) polyamides are a class of programmable DNA minor groove binders capable of modulating the activity of DNA-binding proteins and affecting changes in gene expression. Estrogen Receptor Alpha (ERα) is a ligand-activated hormone receptor that binds as a homodimer to estrogen response elements (EREs) and is a driving oncogene in a majority of breast cancers. We tested a selection of structurally similar Py-Im polyamides with differing DNA sequence specificity for activity against 17β-estadiol (E2) induced transcription and cytotoxicity in ERα positive, E2 stimulated T47D-KBLUC cells, which express luciferase under ERα control. The most active polyamide targeted the sequence: 5’-WGGWCW-3’ (W = A or T), which is the canonical ERE-half site. Whole transcriptome analysis using RNA-Seq revealed that treatment of E2-stimulated breast cancer cells with this polyamide reduced the effects of E2 on the majority of those most strongly affected by E2, but had much less effect on the majority of E2 induced transcripts. In vivo, this polyamide circulated at detectable levels following subcutaneous injection and reduced levels of ER-driven luciferase expression in xenografted tumors in mice after subcutaneous compound administration without significant host toxicity. PMID:23443804

  14. A Finite Element Study of the Dynamic Response of Brain Based on Two Parasagittal Slice Models

    PubMed Central

    Song, Xuewei; Wang, Cong; Hu, Hao; Huang, Tianlun; Jin, Jingxu

    2015-01-01

    The objective of this study is to investigate the influence of gyri and sulci on the response of human head under transient loading. To this end, two detailed parasagittal slice models with and without gyri and sulci have been developed. The models comprised not only cerebrum and skull but also cerebellum, brain stem, CSF, and corpus callosum. In addition, white and gray matters were separated. The material properties were adopted from the literature and assigned to different parts of the models. Nahum's and Trosseille's experiments reported in relevant literature were simulated and the simulation results were compared with the test data. The results show that there is no evident difference in terms of intracranial pressure between the models with and without gyri and sulci under simulated conditions. The equivalent stress below gyri and sulci in the model with gyri and sulci is slightly higher than that in the counterpart model without gyri and sulci. The maximum principle strain in brain tissue is lower in the model with gyri and sulci. The stress and strain distributions are changed due to the existence of gyri and sulci. These findings highlight the necessity to include gyri and sulci in the finite element head modeling. PMID:26495034

  15. 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.

  16. Optimal placement of trailing-edge flaps for helicopter vibration reduction using response surface methods

    NASA Astrophysics Data System (ADS)

    Viswamurthy, S. R.; Ganguli, Ranjan

    2007-03-01

    This study aims to determine optimal locations of dual trailing-edge flaps to achieve minimum hub vibration levels in a helicopter, while incurring low penalty in terms of required trailing-edge flap control power. An aeroelastic analysis based on finite elements in space and time is used in conjunction with an optimal control algorithm to determine the flap time history for vibration minimization. The reduced hub vibration levels and required flap control power (due to flap motion) are the two objectives considered in this study and the flap locations along the blade are the design variables. It is found that second order polynomial response surfaces based on the central composite design of the theory of design of experiments describe both objectives adequately. Numerical studies for a four-bladed hingeless rotor show that both objectives are more sensitive to outboard flap location compared to the inboard flap location by an order of magnitude. Optimization results show a disjoint Pareto surface between the two objectives. Two interesting design points are obtained. The first design gives 77 percent vibration reduction from baseline conditions (no flap motion) with a 7 percent increase in flap power compared to the initial design. The second design yields 70 percent reduction in hub vibration with a 27 percent reduction in flap power from the initial design.

  17. Creation of Principally New Generation of Switching Technique Elements (Reed Switches) with Nanostructured Contact Surfaces

    NASA Astrophysics Data System (ADS)

    Karabanov, S. M.; Zeltser, I. A.; Maizels, R. M.; Moos, E. N.; Arushanov, K. A.

    2011-04-01

    The cycle of activities of the creation of principally new generation of reed switches with nanostructured contact surfaces was implemented. Experimental justification of the opportunity of reed switches creation with modified contact surface was given (instead of precious metals-based galvanic coating). Principally new technological process of modification of magnetically operated contacts contacting surfaces was developed, based on the usage of the ion-plasma methods of nanolayers and nanostructures forming having specified contact features.

  18. Analysis of Usp DNA binding domain targeting reveals critical determinants of the ecdysone receptor complex interaction with the response element.

    PubMed

    Grad, I; Niedziela-Majka, A; Kochman, M; Ozyhar, A

    2001-07-01

    The steroid hormone, 20-hydroxyecdysone (20E), directs Drosophila metamorphosis via a heterodimeric receptor formed by two members of the nuclear hormone receptors superfamily, the product of the EcR (EcR) and of the ultraspiracle (Usp) genes. Our previous study [Niedziela-Majka, A., Kochman, M., Ozyhar, A. (2000) Eur. J. Biochem. 267, 507-519] on EcR and Usp DNA-binding domains (EcRDBD and UspDBD, respectively) suggested that UspDBD may act as a specific anchor that preferentially binds the 5' half-site of the pseudo-palindromic response element from the hsp27 gene promoter and thus locates the heterocomplex in the defined orientation. Here, we analyzed in detail the determinants of the UspDBD interaction with the hsp27 element. The roles of individual amino acids in the putative DNA recognition alpha helix and the roles of the base pairs of the UspDBD target sequence have been probed by site-directed mutagenesis. The results show how the hsp27 element specifies UspDBD binding and thus the polar assembly of the UspDBD/EcRDBD heterocomplex. It is suggested how possible nucleotide deviations within the 5' half-site of the element may be used for the fine-tuning of the 20E-response element specificity and consequently the physiological response. PMID:11432742

  19. The torque ripple reduction of a concentrated winding synchronous reluctance motor according to stator and rotor structure variations using response surface methodology

    NASA Astrophysics Data System (ADS)

    Choi, Yun-Chul; Lee, Jung-Ho; Hong, Jung Pyo

    2008-04-01

    This paper deals with optimum design criteria to minimize the torque ripple of a concentrated winding synchronous reluctance motor (SynRM) using response surface methodology (RSM). The feasibility of using RSM with the finite element method in practical engineering problem is investigated with computational examples and comparison between the fitted response and the results obtained from an analytical solution according to the design variables of stator and rotor in concentrated winding SynRM (6slot).

  20. 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.

  1. Prediction of the mechanical response of canine humerus to three-point bending using subject-specific finite element modelling.

    PubMed

    Laurent, Cédric P; Böhme, Béatrice; Mengoni, Marlène; d'Otreppe, Vinciane; Balligand, Marc; Ponthot, Jean-Philippe

    2016-07-01

    Subject-specific finite element models could improve decision making in canine long-bone fracture repair. However, it preliminary requires that finite element models predicting the mechanical response of canine long bone are proposed and validated. We present here a combined experimental-numerical approach to test the ability of subject-specific finite element models to predict the bending response of seven pairs of canine humeri directly from medical images. Our results show that bending stiffness and yield load are predicted with a mean absolute error of 10.1% (±5.2%) for the 14 samples. This study constitutes a basis for the forthcoming optimization of canine long-bone fracture repair. PMID:27129383

  2. 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...

  3. 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)...

  4. 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.

  5. Effect of Thermal Stresses Along Crack Surface on Ultrasonic Response

    SciTech Connect

    Virkkunen, I.; Haenninen, H.; Kemppainen, M.; Pitkaenen, J.

    2004-02-26

    Artificial flaws can be manufactured by controlled thermal fatigue loading. The produced cracks can be introduced to a wide variety of materials. This technology gives also a unique opportunity to monitor the ultrasonic response of a crack during thermal loading. This paper reports studies on the effects of different thermal load cycles on the ultrasonic response. The loads are analyzed with FEM. Two cracked samples were loaded with different thermal load cycles.

  6. Ensemble averaged surface normal impedance of material using an in-situ technique: preliminary study using boundary element method.

    PubMed

    Otsuru, Toru; Tomiku, Reiji; Din, Nazli Bin Che; Okamoto, Noriko; Murakami, Masahiko

    2009-06-01

    An in-situ measurement technique of a material surface normal impedance is proposed. It includes a concept of "ensemble averaged" surface normal impedance that extends the usage of obtained values to various applications such as architectural acoustics and computational simulations, especially those based on the wave theory. The measurement technique itself is a refinement of a method using a two-microphone technique and environmental anonymous noise, or diffused ambient noise, as proposed by Takahashi et al. [Appl. Acoust. 66, 845-865 (2005)]. Measured impedance can be regarded as time-space averaged normal impedance at the material surface. As a preliminary study using numerical simulations based on the boundary element method, normal incidence and random incidence measurements are compared numerically: results clarify that ensemble averaging is an effective mode of measuring sound absorption characteristics of materials with practical sizes in the lower frequency range of 100-1000 Hz, as confirmed by practical measurements. PMID:19507960

  7. Finite element analysis of the impingement on the acetabular liner rim due to wear of the acetabular liner surface

    NASA Astrophysics Data System (ADS)

    Saputra, Eko; Anwar, Iwan Budiwan; Ismail, Rifky; Jamari, J.; van der Heide, Emile

    2016-04-01

    This workstudies the impingement on the rim of acetabular liner due to wear on the surface of acetabular liner using finite element simulation. A three dimensional contact model between a femoral head and an acetabular liner was developed. There are three steps in this simulation, i.e. creating the virtualwear on the surface of acetabular liner, applying the load at the femoral head, and rotating the femoral head from neutral position till the impingement occurrence. The virtualwear is created based on the data of wear depth which was obtained from literature. Results showed that the wear on the acetabular liner surface wouldaffected the impingement occurrence, in which the impingement angle becomes narrow. In addition, the failure possibility of the acetabular liner rimwould become higher.

  8. HIV-1 p24(gag) derived conserved element DNA vaccine increases the breadth of immune response in mice.

    PubMed

    Kulkarni, Viraj; Rosati, Margherita; Valentin, Antonio; Ganneru, Brunda; Singh, Ashish K; Yan, Jian; Rolland, Morgane; Alicea, Candido; Beach, Rachel Kelly; Zhang, Gen-Mu; Le Gall, Sylvie; Broderick, Kate E; Sardesai, Niranjan Y; Heckerman, David; Mothe, Beatriz; Brander, Christian; Weiner, David B; Mullins, James I; Pavlakis, George N; Felber, Barbara K

    2013-01-01

    Viral diversity is considered a major impediment to the development of an effective HIV-1 vaccine. Despite this diversity, certain protein segments are nearly invariant across the known HIV-1 Group M sequences. We developed immunogens based on the highly conserved elements from the p24(gag) region according to two principles: the immunogen must (i) include strictly conserved elements of the virus that cannot mutate readily, and (ii) exclude both HIV regions capable of mutating without limiting virus viability, and also immunodominant epitopes located in variable regions. We engineered two HIV-1 p24(gag) DNA immunogens that express 7 highly Conserved Elements (CE) of 12-24 amino acids in length and differ by only 1 amino acid in each CE ('toggle site'), together covering >99% of the HIV-1 Group M sequences. Altering intracellular trafficking of the immunogens changed protein localization, stability, and also the nature of elicited immune responses. Immunization of C57BL/6 mice with p55(gag) DNA induced poor, CD4(+) mediated cellular responses, to only 2 of the 7 CE; in contrast, vaccination with p24CE DNA induced cross-clade reactive, robust T cell responses to 4 of the 7 CE. The responses were multifunctional and composed of both CD4(+) and CD8(+) T cells with mature cytotoxic phenotype. These findings provide a method to increase immune response to universally conserved Gag epitopes, using the p24CE immunogen. p24CE DNA vaccination induced humoral immune responses similar in magnitude to those induced by p55(gag), which recognize the virus encoded p24(gag) protein. The inclusion of DNA immunogens composed of conserved elements is a promising vaccine strategy to induce broader immunity by CD4(+) and CD8(+) T cells to additional regions of Gag compared to vaccination with p55(gag) DNA, achieving maximal cross-clade reactive cellular and humoral responses. PMID:23555935

  9. 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

  10. Repression of Wnt/β-catenin response elements by p63 (TP63).

    PubMed

    Katoh, Iyoko; Fukunishi, Nahoko; Fujimuro, Masahiro; Kasai, Hirotake; Moriishi, Kohji; Hata, Ryu-Ichiro; Kurata, Shun-Ichi

    2016-03-01

    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

  11. Exosomes derived from HIV-1-infected cells contain trans-activation response element RNA.

    PubMed

    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

    2013-07-01

    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 10(4)-10(6) copies/ml TAR RNA in exosomes derived from infected culture supernatants and 10(3) 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

  12. 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

  13. 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

  14. Analysis of Response Elements Involved in the Regulation of the Human Neonatal Fc Receptor Gene (FCGRT)

    PubMed Central

    Mikulska, Joanna E.

    2015-01-01

    Human epithelial, endothelial and PMA-differentiated THP-1 cell lines were used as model systems to study the transcriptional regulation of the human FCGRT gene encoding the alpha chain of hFcRn. The data obtained from site-directed mutagenesis in transient transfection experiments indicate that the Sp1 sites at positions -641, -635, and -313, CF1/YY1 elements at positions -586 and -357, and the AP-1 motif at -276 within the-660/-233 fragment of the human FCGRT promoter (hFCGRT) participate in the regulation of human FCGRT in all selected cell lines. However, their individual contribution to promoter activity is not equivalent. The Sp1 binding site at -313 and the AP-1 site at -276 are critical for the activity of the hFCGRT promoter in epithelial and endothelial cells. Moreover, the CF1/YY1 site at -586 in differentiated THP-1 cells, plays an essential role in the transcriptional activity of the promoter. In addition, the C/EBPbeta binding site at -497 of the hFCGRT promoter in epithelial and endothelial cells, and the C/EBPbeta motif located at -497 and -233 within the hFCGRT promoter in differentiated THP-1 cells may function as positive regulatory sequences in response to LPS or PMA stimulation. EMSA and supershift analyses showed that the functionally identified binding motifs in the hFCGRT promoter were able to specifically interact with their corresponding (Sp1, Sp2, Sp3, c-Fos, c-Jun, YY1, and C/EBPbeta or C/EBPdelta) transcription factors (TFs), suggesting their possible involvement in the regulation of the human FCGRT gene expression. PMID:26252948

  15. Oestrogens Downregulate Tissue Factor Pathway Inhibitor through Oestrogen Response Elements in the 5'-Flanking Region.

    PubMed

    Ali, Huda Omar; Stavik, Benedicte; Myklebust, Christiane Filion; Andersen, Elisabeth; Dahm, Anders E A; Iversen, Nina; Sandset, Per Morten; Skretting, Grethe

    2016-01-01

    Oestrogens influence the pathology and development of hormone-sensitive breast cancers. Tissue factor pathway inhibitor (TFPI) has been shown to be associated with breast cancer pathogenesis. Recently, we found TFPI mRNA levels to be significantly reduced by oestrogens in a breast cancer cell line (MCF7), a process mediated through the oestrogen receptor alpha (ERα). The aim of the present study was to investigate the mechanism(s) by which oestrogens may regulate TFPI at the transcriptional level. The TFPI 5'-flanking region contains three oestrogen response element (ERE) half-sites at positions -845, -769 and -50. Constructs containing the wild type or mutated ERE half-sites of the TFPI 5'-flanking region were generated in a luciferase reporter gene vector and transiently co-transfected with an ERα expression vector into HEK293 cells and subsequently treated with oestrogens. We found that luciferase activity was significantly downregulated after oestrogen stimulation in cells transfected with the wild type construct, an effect that was abolished by mutating either ERE half-sites. Electrophoretic mobility shift assay suggested direct and specific interaction of ERα with the ERE half-sites in the TFPI 5'-flanking region. Chromatin immunoprecipitation showed that ERα was recruited to the region -899 to -578 of the TFPI 5'-flanking region in vivo, where the ERE half-sites -845 and -769 are located. Our results indicate that ERα can interact with all three ERE half-sites in the TFPI 5'-flanking region and thus participate in the repression of oestrogen mediated TFPI transcription in breast cancer cells. PMID:26999742

  16. Activation of carbohydrate response element binding protein (ChREBP) by ethanol

    PubMed Central

    Liangpunsakul, Suthat; Ross, Ruth A.; Crabb, David W.

    2012-01-01

    Carbohydrate response element binding protein (ChREBP) is a transcription factor involved in hepatic lipogenesis. Its function is in part under the control of AMP-activated protein kinase (AMPK) and protein phosphatase 2A (PP2A). Given known effects of ethanol on AMPK and PP2A, it is plausible that ethanol might enhance fatty acid synthesis by increasing the activity of ChREBP. We hypothesized that another potential pathway of ethanol-induced hepatic steatosis is mediated by activation of ChREBP. Methods The effects of ethanol on ChREBP were assessed in hepatoma cells and in C57BL/6J mice fed with the Lieber-DeCarli diet. Results When the cells were exposed to ethanol (50 mM) for 24 hrs, the activity of a liver pyruvate kinase (LPK) promoter-luciferase reporter was increased by ~4-fold. Ethanol feeding of mice resulted in the translocation of ChREBP from cytosol to the nucleus. PP2A activity was increased in the liver of ethanol-fed mice by 22%. We found no difference in the levels of hepatic Xu-5-P between ethanol-fed mice and controls. Transfection of a constitutively active AMPK expression plasmid suppressed the basal activity of the LPK luciferase reporter and abolished the effect of ethanol on the reporter activity. However, transfection of rat hepatoma cells with a dominant negative AMPK expression plasmid induced basal LPK luciferase activity by only ~20%. The effect of ethanol on ChREBP was attenuated in the presence of okadaic acid, an inhibitor of PP2A. Conclusions The effects of ethanol on AMPK and PP2A may result in activation of ChREBP, providing another potential mechanism for ethanol-induced hepatic steatosis. However, additional okadaic acid-insensitive effects appear to be important as well. PMID:23266705

  17. Identification and characterization of an estrogen-responsive element binding protein repressed by estradiol.

    PubMed

    Gray, W G; Gorski, J

    1996-09-10

    Cytosolic proteins from uteri of 19-day-old rats were analyzed by an electrophoresis mobility shift assay (EMSA) using a 31 base pair DNA probe containing an estrogen-responsive element (ERE) from the vitellogenin A2 gene. EMSA identified three distinct cytosolic protein-DNA complexes that are separable by Q-Sepharose anion exchange chromatography into an estrogen receptor (ER)-containing fraction (150 mM NaCl eluate) and a non-ER-containing fraction (250 mM NaCl eluate). We thus refer to the non-ER fraction as the ERE binding protein (ERE-BP). The ERE-BP-containing fraction was repressed to 40-50% of its normal levels following a single injection of estradiol. In addition, ERE-BP levels were repressed to the same extent (greater than 50%) by day 20 of the rat's gestational period. Examination of the expression pattern of ERE-BP shows that this activity is differentially expressed in both estrogen-responsive and nonresponsive tissues, with the highest levels of expression occurring in the pituitary. We next examined the specificity of ERE-BP binding by competition analysis using DNA sequences corresponding to binding sites of several known transcription factors. ERE-BP was found to be specific for both the ER binding site (ERE) and TATA binding protein binding sites. Furthermore, saturation analysis demonstrated that ERE-BP binds to the ERE and TATA binding protein sequences with an apparent Kd of 1.2 and 0.12 nM, respectively. Partial purification of ERE-BP using three chromatography steps (Q-Sepharose, hydroxyapatite, and Sephacryl S300) followed by sodium dodecyl sulfate analysis indicated the presence of three major protein bands (p102, p81, and p48) as judged by Coomassie staining. UV cross-linking of the ERE-BP/DNA complex followed by sodium dodecyl sulfate analysis-polyacrylamide gel electrophoresis analysis indicates that the 48 kDa band seen in the final, partially purified fraction correlates with the ERE-BP activity. Thus, this study has identified a

  18. Specification of the surface figure and finish of optical elements in terms of system performance

    SciTech Connect

    Church, E.L.; Takacs, P.Z.

    1992-09-01

    Brookhaven National Laboratory is the site of the National Synchrotron Light Source (NSLS); an electron synchrotron which is an intense source of hard and soft x-rays. Since there are no effective refracting elements for x rays, this radiation must be manipulated and focused by mirrors configured to give high reflectivity. This paper describes methods of predicting the degradation of the performance of a simple imaging system in terms of the statistics of the shape errors of the focusing element, and conversely, of specifying those statistics in terms of requirements on image quality. Results are illustrated for a normal-incidence x-ray mirrors having figure errors plus conventional and/or fractal finish errors.

  19. Enzyme-enabled responsive surfaces for anti-contamination materials.

    PubMed

    Wu, Songtao; Buthe, Andreas; Jia, Hongfei; Zhang, Minjuan; Ishii, Masahiko; Wang, Ping

    2013-06-01

    Many real-life stains have origins from biological matters including proteins, lipids, and carbohydrates that act as gluing agents binding along with other particulates or microbes to exposed surfaces of automobiles, furniture, and fabrics. Mimicking naturally occurring self-defensive processes, we demonstrate in this work that a solid surface carrying partially exposed enzyme granules protected the surface in situ from contamination by biological stains and fingerprints. Attributed to the activities of enzymes which can be made compatible with a wide range of materials, such anti-contamination and self-cleaning functionalities are highly selective and efficient toward sticky chemicals. This observation promises a new mechanism in developing smart materials with desired anti-microbial, self-reporting, self-cleaning, or self-healing functions. PMID:23335427

  20. Texture as a visual cueing element in computer image generation. I. Representation of the sea surface

    SciTech Connect

    Bookout, G.; Sinacori, J.

    1993-01-01

    The objective of this paper is to advance hypotheses about texture as a visual cueing medium in simulation and to provide guidelines for data base modelers in the use of computer image generator resources to provide effective visual cues for simulation purposes. The emphasis is on a texture decoration of the earth's surface data base in order to support low-level flight, i.e., flight at elevations above the surface of 500 feet or less. The appearance of the surface of the sea is the focus of this paper. The physics of the sea's appearance are discussed and guidelines are given for its representation for sea states from 0 (calm) to 5 (fresh breeze of 17-21 knots and sixfoot waves, peak-to-trough). The viewpoints considered vary from 500 feet above the mean sea surface to an altitude just above the wave crests. 7 refs.

  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. Hypoxia-induced endothelial NO synthase gene transcriptional activation is mediated through the tax-responsive element in endothelial cells.

    PubMed

    Min, Jiho; Jin, Yoon-Mi; Moon, Je-Sung; Sung, Min-Sun; Jo, Sangmee Ahn; Jo, Inho

    2006-06-01

    Although hypoxia is known to induce upregulation of endothelial NO synthase (eNOS) gene expression, the underlying mechanism is largely unclear. In this study, we show that hypoxia increases eNOS gene expression through the binding of phosphorylated cAMP-responsive element binding (CREB) protein (pCREB) to the eNOS gene promoter. Hypoxia (1% O2) increased both eNOS expression and NO production, peaking at 24 hours, in bovine aortic endothelial cells, and these increases were accompanied by increases in pCREB. Treatment with the protein kinase A inhibitor H-89 or transfection with dominant-negative inhibitor of CREB reversed the hypoxia-induced increases in eNOS expression and NO production, with concomitant inhibition of the phosphorylation of CREB induced by hypoxia, suggesting an involvement of protein kinase A/pCREB-mediated pathway. To map the regulatory elements of the eNOS gene responsible for pCREB binding under hypoxia, we constructed an eNOS gene promoter (-1600 to +22 nucleotides) fused with a luciferase reporter gene [pGL2-eNOS(-1600)]. Hypoxia (for 24-hour incubation) increased the promoter activity by 2.36+/-0.18-fold in the bovine aortic endothelial cells transfected with pGL2-eNOS(-1600). However, progressive 5'-deletion from -1600 to -873 completely attenuated the hypoxia-induced increase in promoter activity. Electrophoretic mobility shift, anti-pCREB antibody supershift, and site-specific mutation analyses showed that pCREB is bound to the Tax-responsive element (TRE) site, a cAMP-responsive element-like site, located at -924 to -921 of the eNOS promoter. Our data demonstrate that the interaction between pCREB and the Tax-responsive element site within the eNOS promoter may represent a novel mechanism for the mediation of hypoxia-stimulated eNOS gene expression. PMID:16651461

  3. Summer Surface Layer Thermal Response to Surface Gravity Waves in the Yellow Sea and the East China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Han, G.; Deng, Z.; Wang, X.

    2010-12-01

    A three-dimensional ocean model is applied to study the summer surface layer thermal response to surface gravity waves in the Yellow sea and the East China Sea(YES).The parameterization schemes of wave breaking developed by Mellor and Blumberg(2004) and Langmuir circulation developed by Kantha and Clayson(2004) are both included in the Mellor-Yamada turbulence closure model(Mellor and Yamada, 1982). Numerical results show that both surface wave breaking and Langmuir circulation determine the depth of surface boundary layer of temperature in the YES in summer. Langmuir circulation is able to obtain the turbulent kinetic energy injected by breaking waves near the surface and transport it downward to greater depths. A diagnostic analysis of the momentum balance shows that surface gravity waves can decrease the velocity near the surface and make the flow near the surface more homogeneous vertically in the YES. In addition, a diagnostic analysis of the temperature equation has been done for studying the heat budget. Diagnostic results show that more heat that is brought from surface in the YES can been transferred into the deeper layer owing to the surface gravity waves, which can induce local temperature there increase more rapidly. Besides, diagnostic results also suggest that surface gravity waves are likely to decrease upwelling near the bank in the region.

  4. 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

  5. Measurement of Trace Elements During the Development and Immune Response of Heliothis virescens Larvae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While many studies have examined the effect of microbial infections on the status of trace elements in mammalian tissues, similar studies have not been performed in insects. We used inductively coupled plasma-mass spectrometry (ICP-MS) to quantify changes in trace elements of Mg, Mn, Fe, Cu, Zn and ...

  6. 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...

  7. 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.

  8. 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.

  9. Functional analysis of the Arabidopsis PLDZ2 promoter reveals an evolutionarily conserved low-Pi-responsive transcriptional enhancer element

    PubMed Central

    Oropeza-Aburto, Araceli; Cruz-Ramírez, Alfredo; Acevedo-Hernández, Gustavo J.; Pérez-Torres, Claudia-Anahí; Caballero-Pérez, Juan; Herrera-Estrella, Luis

    2012-01-01

    Plants have evolved a plethora of responses to cope with phosphate (Pi) deficiency, including the transcriptional activation of a large set of genes. Among Pi-responsive genes, the expression of the Arabidopsis phospholipase DZ2 (PLDZ2) is activated to participate in the degradation of phospholipids in roots in order to release Pi to support other cellular activities. A deletion analysis was performed to identify the regions determining the strength, tissue-specific expression, and Pi responsiveness of this regulatory region. This study also reports the identification and characterization of a transcriptional enhancer element that is present in the PLDZ2 promoter and able to confer Pi responsiveness to a minimal, inactive 35S promoter. This enhancer also shares the cytokinin and sucrose responsive properties observed for the intact PLDZ2 promoter. The EZ2 element contains two P1BS motifs, each of which is the DNA binding site of transcription factor PHR1. Mutation analysis showed that the P1BS motifs present in EZ2 are necessary but not sufficient for the enhancer function, revealing the importance of adjacent sequences. The structural organization of EZ2 is conserved in the orthologous genes of at least eight families of rosids, suggesting that architectural features such as the distance between the two P1BS motifs are also important for the regulatory properties of this enhancer element. PMID:22210906

  10. 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.

  11. On the Surface of Phenomenography: A Response to Graham Webb.

    ERIC Educational Resources Information Center

    Ekeblad, Eva

    1997-01-01

    Challenges a critique of phenomenography and the idea that college students approach studies in ways leading to either "deep" or "surface" learning. Finds the description of phenomenography to be unrecognizable and based on inadequate review of the literature. Sees this attempt to invalidate this approach to research about knowledge as reflecting…

  12. 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

  13. 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

  14. Aquifer response to surface water transience in disconnected streams

    NASA Astrophysics Data System (ADS)

    Shanafield, Margaret; Cook, Peter G.; Brunner, Philip; McCallum, James; Simmons, Craig T.

    2012-11-01

    Existing analytical solutions to determine aquifer response to a change in stream stage are inappropriate where an unsaturated zone exists beneath the stream, as in the case of disconnected stream-aquifer systems. A better understanding of the relationship between aquifer response and transient stream stage in disconnected systems is therefore required, as this would also aid in the field determination of the status of connection between the stream and aquifer. We use a numerical model to examine transient stream stage and the corresponding water table response. Beneath disconnected streams, the magnitude of head change in the water table level is a balance between the cumulative infiltration during a flow event and the rate at which the water can disperse laterally. Increases in wave duration, stream width, and streambed permeability result in greater infiltrated water volume and therefore a higher peak response at the water table. Conversely, higher aquifer transmissivity and aquifer hydraulic conductivity allow the water to move laterally away from the stream faster, resulting in a smaller head change below the stream. Lower unsaturated storage results in a greater and faster aquifer response because the unsaturated zone can fill more quickly. Under some combinations of parameters, the magnitude of the disconnected head response is more than seven times greater than the change in stream stage driving streambed infiltration; an effect which can never occur beneath a connected stream. The results of this sensitivity analysis are compared to field data from a river in eastern Australia to determine periods of disconnection. Where the change in aquifer head is greater than the change in stream stage, disconnection between the stream and aquifer can be determined.

  15. Transcriptional induction of the mouse metallothionein-I gene in hydrogen peroxide-treated Hepa cells involves a composite major late transcription factor/antioxidant response element and metal response promoter elements.

    PubMed Central

    Dalton, T; Palmiter, R D; Andrews, G K

    1994-01-01

    Synthesis of metallothionein-I (MT-I) and heme oxygenase mRNAs is rapidly and transiently induced by H2O2 in mouse hepatoma cells (Hepa) and this effect is blocked by catalase. Menadione, which generates free radicals, also induces these mRNAs. Deletion mutagenesis revealed that a region between -42 and -153 in the mouse MT-I promoter was essential for induction of a CAT reporter gene. A multimer of a 16 bp sequence (-101 to -86) that includes an antioxidant response element and overlapping adenovirus major late transcription factor binding site elevated basal expression and allowed induction by H2O2 when inserted upstream of a minimal promoter. However, deletion of this region (-100 to -89) from the intact MT-I promoter (-153) did not completely eliminate response. Multiple copies of a metal response element also permitted response to H2O2. These results suggest that induction of MT-I gene transcription by H2O2 is mediated by at least two different elements within the proximal MT-I gene promoter and suggest a previously undescribed function of the MRE. Induction of MT gene transcription by ROS and the subsequent scavenging of ROS by the MT peptide is reminiscent of the metal regulatory loop and is consistent with the hypothesized protective functions of MT. Images PMID:7800494

  16. 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

  17. Radioactive Elements on Mercury’s Surface from MESSENGER: Implications for the Planet’s Formation and Evolution

    NASA Astrophysics Data System (ADS)

    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.

    2011-09-01

    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.

  18. 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.

  19. 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

  20. Isolation of a non-genomic origin fluoroquinolone responsive regulatory element using a combinatorial bioengineering approach.

    PubMed

    Srivastava, Santosh Kumar; Iyer, V Rajesh; Ghosh, Tamoghna; Lambadi, Paramesh Ramulu; Pathania, Ranjana; Navani, Naveen Kumar

    2016-03-18

    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

  1. Design, tolerance, and fabrication of an optical see-through head-mounted display with free-form surface elements.

    PubMed

    Wang, Qingfeng; Cheng, Dewen; Wang, Yongtian; Hua, Hong; Jin, Guofan

    2013-03-01

    Free-form surfaces (FFSs) provide more freedom to design an optical system with fewer elements and hence to reduce the size and weight of the overall system than rotationally symmetric optical surfaces. In this paper, an optical see-through (OST), head-mounted display (HMD) consisting of a free-form, wedge-shaped prism and a free-form lens is designed and fabricated through the injection molding method. The free-form prism for the projection system is designed with a field-of-view (FOV) of 36°; the free-form lens is cemented to the prism for the see-through system to achieve a FOV of 50°. The free-form prism and lens are expanded at the edge area during the design stage in order to reduce the effects of surface deformation in the working area in molding fabrication process and to improve ergonomic fit with the head of a user. The tolerance analyzes considering the mold design for the free-form optical systems are carried out using the Monte Carlo method. The FFS optical elements are successfully fabricated and the system performance is carefully examined. The results indicate that the performance of the OST-HMD is sufficient for both entertainment and scientific applications. PMID:23458822

  2. Guidelines for Designing Surface Ion Traps Using the Boundary Element Method.

    PubMed

    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

  3. 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

  4. 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.

  5. 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

  6. Distribution of major and trace elements in surface sediments of the western Gulf of Thailand: Implications to modern sedimentation

    NASA Astrophysics Data System (ADS)

    Liu, Shengfa; Shi, Xuefa; Yang, Gang; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

    2016-04-01

    In this study, we analyze major and trace elements (SiO2, Al2O3, Fe2O3, CaO, K2O, MgO, Na2O, TiO2, P2O5, MnO, Cu, Pb, Ba, Sr, V, Zn, Co, Ni, Cr, and Zr) and grain size of 157 surface sediment samples from the western Gulf of Thailand (GoT). On the basis of the space distribution characteristics, the study area can be classified into three geochemical provinces. Province I covers the northern and northwestern coastal zones of the GoT, including the whole upper GoT and thus the sediments from the rivers in the area. It contains high contents of SiO2. Province II is located in the middle of the GoT and has similar geochemistry composition as the South China Sea (SCS). It contains sediments that are characterized by higher contents of Na2O, TiO2, Ba, Cr, V, Zn, Zr, and Ni. Province Ш is located in the lower GoT, close to Malaysia. Major and trace elements in this area showed complex distribution patterns, which may be due to terrestrial materials from Malay rivers combining with some sediments from the SCS in this province. The results also indicate that grain size is the controlling factor in elemental contents, and that the hydrodynamic environment and mineral composition of the sediments play an important role in the distribution of these elements. The anthropogenic impact of heavy metal introduction (especially Cr, Zn, Cu, and Pb) can be seen in surface sediments from the nearshore region of Chantaburi province and north of Samui Island.

  7. 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.

  8. 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

  9. 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. PMID:26704296

  10. 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

  11. Effects of surface active elements on weld pool fluid flow and weld penetration in gas metal arc welding

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Tsai, H. L.

    2001-06-01

    This article presents a mathematical model simulating the effects of surface tension (Maragoni effect) on weld pool fluid flow and weld penetration in spot gas metal arc welding (GMAW). Filler droplets driven by gravity, electromagnetic force, and plasma arc drag force, carrying mass, thermal energy, and momentum, periodically impinge onto the weld pool. Complicated fluid flow in the weld pool is influenced by the droplet impinging momentum, electromagnetic force, and natural convection due to temperature and concentration gradients, and by surface tension, which is a function of both temperature and concentration of a surface active element (sulfur in the present study). Although the droplet impinging momentum creates a complex fluid flow near the weld pool surface, the momentum is damped out by an “up-and-down” fluid motion. A numerical study has shown that, depending upon the droplet’s sulfur content, which is different from that in the base metal, an inward or outward surface flow of the weld pool may be created, leading to deep or shallow weld penetration. In other words, it is primarily the Marangoni effect that contributes to weld penetration in spot GMAW.

  12. 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 bi