WorldWideScience

Sample records for surface stress values

  1. Ocean surface wind stress

    Science.gov (United States)

    Harrison, D. E.

    1984-01-01

    The need for improved surface wind and wind stress data is discussed. The collection of wind data using ship reports, research buoys, and cloud motion vectors is examined. The need for data on surface-wind stress fields is emphasized. Accurate stress data are required for studying: (1) the normal seasonal cycle and the intraannual events; (2) wind stress curls and the forcing of ocean circulation; (3) El Nino events; and (4) the low response of the midlatitude ocean circulation.

  2. Relieving stress through value-rich work.

    Science.gov (United States)

    Knoop, R

    1994-12-01

    On the basis of Herzberg, Mausner, and Snyderman's (1959) motivator-hygiene theory, it was hypothesized that intrinsic but not extrinsic work values would be inversely related to stress. Also investigated was the question of which work values provide the most relief from stress. Elementary school teachers and administrators (N = 607) from nine school boards in southern Ontario completed a survey that included Pines, Aronson, and Kafry's (1981) stress scale and Elizur's (1984) work values scale. Almost all of the 12 intrinsic work values investigated were negatively correlated with stress, but the 4 extrinsic work values studied were not consistently related to stress. Five work values explained 11% of the variance in physical stress, 9 work values explained 22% of the variance in emotional stress, and 6 work values explained 26% of the variance in mental stress. Four work values emerged as meaningful predictors of all three types of stress: being esteemed by others, achieving through work, doing meaningful work, and being able to use one's knowledge and abilities.

  3. Surface stress-based biosensors.

    Science.gov (United States)

    Sang, Shengbo; Zhao, Yuan; Zhang, Wendong; Li, Pengwei; Hu, Jie; Li, Gang

    2014-01-15

    Surface stress-based biosensors, as one kind of label-free biosensors, have attracted lots of attention in the process of information gathering and measurement for the biological, chemical and medical application with the development of technology and society. This kind of biosensors offers many advantages such as short response time (less than milliseconds) and a typical sensitivity at nanogram, picoliter, femtojoule and attomolar level. Furthermore, it simplifies sample preparation and testing procedures. In this work, progress made towards the use of surface stress-based biosensors for achieving better performance is critically reviewed, including our recent achievement, the optimally circular membrane-based biosensors and biosensor array. The further scientific and technological challenges in this field are also summarized. Critical remark and future steps towards the ultimate surface stress-based biosensors are addressed.

  4. Determining Electrochemical Surface Stress of Single Nanowires.

    Science.gov (United States)

    Wang, Hui; Shan, Xiaonan; Yu, Hui; Wang, Yan; Schmickler, Wolfgang; Chen, Hong-Yuan; Tao, Nongjian

    2017-02-13

    Electrochemical surface stress is important in nanomaterials because of their large surface-to-volume ratios, which lead to unique mechanical and electrocatalytic properties, but directly measuring this quantity has been challenging. Here we report on experimental determination of the surface stress, and associated electrochemical processes of a single gold nanowire with an optical imaging technique. We show that surface stress changes linearly and reversibly with the potential between 0 and 0.8 V versus Ag/AgCl, but abruptly with large hysteresis, associated with the oxidation and reduction of the nanowire, between 0.8 and 1.5 V. The potential derivative of the surface stress closely resembles the cyclic voltammograms. We described the observations in terms of anion adsorption and surface oxidation/reduction. This work demonstrates a new approach to study electrochemical processes and the associated surface stress changes of nanomaterials.

  5. A Family of Invariant Stress Surfaces

    DEFF Research Database (Denmark)

    Krenk, S.

    A family of invariant stress surfaces with a cubic dependence on the deviatoric stress components is expressed as a linear combination of the second and third deviatori stress invariants. A simple geometric derivation demonstrates the convexity of the contours in the deviatoric plane. An explicit...

  6. Temperature limit values for gripping cold surfaces

    NARCIS (Netherlands)

    Malchaire, J.; Geng, Q.; Den Hartog, E.; Havenith, G.; Holmer, I.; Piette, A.; Powell, S.L.; Rintamäki, H.; Rissanen, S.

    2002-01-01

    Objectives. At the request of the European Commission and in the framework of the European Machinery Directive, research was conducted jointly in five different laboratories to develop specifications for surface temperature limit values for the gripping and handling of cold items. Methods. Four

  7. Temperature limit values for gripping cold surfaces

    NARCIS (Netherlands)

    Malchaire, J.; Geng, Q.; Den Hartog, E.; Havenith, G.; Holmer, I.; Piette, A.; Powell, S.L.; Rintamäki, H.; Rissanen, S.

    2002-01-01

    Objectives. At the request of the European Commission and in the framework of the European Machinery Directive, research was conducted jointly in five different laboratories to develop specifications for surface temperature limit values for the gripping and handling of cold items. Methods. Four hund

  8. Teacher Stress and Personal Values. An Exploratory Study

    Science.gov (United States)

    Bachkirova, Tatiana

    2005-01-01

    This article presents the first stage of a small-scale research project into the relationship between teacher stress and personal values. It starts by outlining the problem of teacher stress and an overview of the literature investigating the sources of it. A particular combination of factors related to personal values that may increase…

  9. Teacher Stress and Personal Values. An Exploratory Study

    Science.gov (United States)

    Bachkirova, Tatiana

    2005-01-01

    This article presents the first stage of a small-scale research project into the relationship between teacher stress and personal values. It starts by outlining the problem of teacher stress and an overview of the literature investigating the sources of it. A particular combination of factors related to personal values that may increase…

  10. Influence of surface stresses on indentation response

    Science.gov (United States)

    Buchwald, J.; Mayr, S. G.

    2015-03-01

    Surface stresses lead to an effective change in the elastic constants of thin films and at surfaces. The development of modern scanning probe techniques like contact resonance atomic force microscopy empowers the experimenter to measure at scales where these effects become increasingly relevant. In this paper we employ a computational multiscale approach where we compare density functional theory (DFT) and molecular dynamics simulations as tools to calculate the thin-film/surface elastic behavior for silicon and strontiumtitanate. From the surface elastic constants gained by DFT calculations we develop a continuum finite-element multilayer model to study the impact of surface stresses on indentation experiments. In general the stress field of an indenter and thus the impact of surface stresses on the indentation modulus depends on its contact radius and on its particular shape. We propose an analytical model that describes the behavior of the indentation modulus as a function of the contact radius. We show that this model fits well to simulation results gained for a spherical and a flat punch indenter. Our results demonstrate a surface-stress-induced reduction of the indentation modulus of about 5% for strontiumtitanate and 6% for silicon for a contact radius of {{r}c}=5 \\text{nm}, irrespective of the indenter shape.

  11. Surface stress, surface elasticity, and the size effect in surface segregation

    DEFF Research Database (Denmark)

    Schmid, M.; Hofer, W.; Varga, P.;

    1995-01-01

    Surface stress and surface elasticity of low-index fcc surfaces have been studied using effective-medium theory potentials. In addition to total-energy calculations giving stress components and elastic data for the surface as a whole, the use of artificial atoms with modified size allows us...

  12. Prediction and Optimization of Residual Stresses on Machined Surface and Sub-Surface in MQL Turning

    Science.gov (United States)

    Ji, Xia; Zou, Pan; Li, Beizhi; Rajora, Manik; Shao, Yamin; Liang, Steven Y.

    Residual stress in the machined surface and subsurface is affected by materials, machining conditions, and tool geometry and can affect the component life and service quality significantly. Empirical or numerical experiments are commonly used for determining residual stresses but these are very expensive. There has been an increase in the utilization of minimum quantity lubrication (MQL) in recent years in order to reduce the cost and tool/part handling efforts, while its effect on machined part residual stress, although important, has not been explored. This paper presents a hybrid neural network that is trained using Simulated Annealing (SA) and Levenberg-Marquardt Algorithm (LM) in order to predict the values of residual stresses in cutting and radial direction on the surface and within the work piece after the MQL face turning process. Once the ANN has successfully been trained, an optimization procedure, using Genetic Algorithm (GA), is applied in order to find the best cutting conditions in order to minimize the surface tensile residual stresses and maximize the compressive residual stresses within the work piece. The optimization results show that the usage of MQL decreases the surface tensile residual stresses and increases the compressive residual stresses within the work piece.

  13. Effect of the residual stresses on surface coercive force in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tejedor, M.; Garcia, J.A.; Carrizo, J.; Elbaile, L. E-mail: elbaile@pinon.ccu.uniovi.es; Santos, J.D

    2000-06-02

    The dependence of the coercivity H{sub c} on the applied stress {sigma} in the surfaces of various amorphous ribbons with positive magnetostriction is studied. The results obtained show that the behaviour of H{sub c}({sigma}) in the surfaces is the same as in the bulk and the minimum of H{sub c}({sigma}) does not depend on the residual stresses. The residual stresses affect the value of the coercive field but not its stress dependence.

  14. Corroding and Protecting of Surface Residual Stress With the Surface Hardening of Steel

    Institute of Scientific and Technical Information of China (English)

    ZOU Qing-hua

    2004-01-01

    The states of the stress with the surface hardening are analyzed, the related experiential formula of the stress -temperature and stress-depth hardened curves are set up, the protecting measures against hydrogen stress corrosion are discussed.

  15. Laser pulse heating of surfaces and thermal stress analysis

    CERN Document Server

    Yilbas, Bekir S; Al-Aqeeli, Nasser; Al-Qahtani, Hussain M

    2013-01-01

    This book introduces laser pulse heating and thermal stress analysis in materials surface. Analytical temperature treatments and stress developed in the surface region are also explored. The book will help the reader analyze the laser induced stress in the irradiated region and presents solutions for the stress field. Detailed thermal stress analysis in different laser pulse heating situations and different boundary conditions are also presented. Written for surface engineers.

  16. SHAPE BIFURCATION OF AN ELASTIC WAFER DUE TO SURFACE STRESS

    Institute of Scientific and Technical Information of China (English)

    闫琨; 何陵辉; 刘人怀

    2003-01-01

    A geometrically nonlinear analysis was proposed for the deformation of a freestanding elastically isotropic wafer caused by the surface stress change on one surface. Thelink between the curvature and the change in surface stress was obtained analytically fromenergetic consideration. In contrast to the existing linear analysis, a remarkableconsequence is that, when the wafer is very thin or the surface stress difference between thetwo major surfaces is large enough, the shape of the wafer will bifurcate.

  17. 10 CFR Appendix D to Part 835 - Surface Contamination Values

    Science.gov (United States)

    2010-01-01

    ... to radioactive contamination deposited on, but not incorporated into the interior or matrix of, the... 10 Energy 4 2010-01-01 2010-01-01 false Surface Contamination Values D Appendix D to Part 835...—Surface Contamination Values The data presented in appendix D are to be used in identifying the need for...

  18. Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'.

    Science.gov (United States)

    Gutman, E M

    2010-10-27

    In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity.

  19. The surface stress theory of microbial morphogenesis.

    Science.gov (United States)

    Koch, A L

    1983-01-01

    From the physics of the situation, one might conclude that the osmotic pressure within most prokaryotes creates a sufficiently high tension in the wall that organisms are at risk of ripping themselves apart. The Surface Stress Theory holds that they avoid this, and are able to carry out certain morphogenetic processes by linking the cleavages of appropriate bonds to enzymes that are sensitive to the stress in the bonds under attack. This tends to maintain the internal pressure and couples wall growth to cytoplasmic growth. Mechanisms with widely different geometry function for different organisms, but they have in common the requirement that new murein be covalently linked, and usually in an unextended conformation. Organisms differ in the site of wall addition and site of cleavage. In the Gram-positive Streptococcus, septum formation, and septal splitting occurs with little stretching of the unsplit septum. In Gram-positive bacilli, the cylinder grows by the inside-to-outside mechanism, and the poles appear to be formed by a split-and-stretch mechanism. Gram-negative rods, with their much thinner wall, resist a spherical shape and are capable of cell division by altering the biochemical mechanism so that initially one-third to one-fifth of the pressure-volume work required to increase the area of the side wall is needed to increase that in a developing pole. The growth of hyphae is a separate case; it requires that much less work is needed to force growth of the apex relative to the side wall. Some other bacterial shapes also can be explained by the theory. But at present, it is only a theory, although it is gradually becoming capable of accounting for current observations in detail. Its importance is that it prescribes many experiments that now need to be done.

  20. Determination of Surface Stress Distributions in Steel Using Laser-Generated Surface Acoustic Waves

    Science.gov (United States)

    Shi; Yifei; Ni; Chenyin; Shen; Zhonghua; Ni; Xiaowu; Lu; Jian

    2008-05-01

    High frequency surface acoustic waves (SAWs) are excited by a pulsed laser and detected by a specially designed poly(vinylidene fluoride) (PVDF) transducer to investigate surface stress distribution. Two kinds of stressed surfaces are examined experimentally. One is a steel plate elastically deformed under simple bending forces, where the surface stress varies slowly. The other is a welded steel plate for which the surface stress varies very rapidly within a small area near the welding seam. Applying a new signal processing method developed from correlation technique, the velocity distribution of the SAWs, which reflects the stress distribution, is obtained in these two samples with high resolution.

  1. Effect of Surface Topography on Stress Concentration Factor

    Institute of Scientific and Technical Information of China (English)

    CHENG Zhengkun; LIAO Ridong

    2015-01-01

    Neuber rule and Arola-Ramulu model are widely used to predict the stress concentration factor of rough specimens. However, the height parameters and effective valley radius used in these two models depend strongly on the resolution of the roughness-measuring instruments and are easily introduce measuring errors. Besides, it is difficult to find a suitable parameter to characterize surface topography to quantitatively describe its effect on stress concentration factor. In order to overcome these disadvantages, profile moments are carried out to characterize surface topography, surface topography is simulated by superposing series of cosine components, the stress concentration factors of different micro cosine-shaped surface topographies are investigated by finite element analysis. In terms of micro cosine-shaped surface topography, an equation using the second profile moment to estimate the stress concentration factor is proposed, predictions for the stress concentration factor using the proposed expression are within 10% error compared with the results of finite element analysis, which are more accurate than other models. Moreover, the proposed equation is applied to the real surface topography machined by turning. Predictions for the stress concentration factor using the proposed expression are within 10% of the maximum stress concentration factors and about 5% of the effective stress concentration factors estimated from the finite element analysis for three levels of turning surface topographies under different simulated scales. The proposed model is feasible in predicting the stress concentration factors of real machined surface topographies.

  2. Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies.

    Science.gov (United States)

    Olives, Juan

    2010-03-01

    The thermodynamics and mechanics of the surface of a deformable body are studied here, following and refining the general approach of Gibbs. It is first shown that the 'local' thermodynamic variables of the state of the surface are only the temperature, the chemical potentials and the surface strain tensor (true thermodynamic variables, for a viscoelastic solid or a viscous fluid). A new definition of the surface stress is given and the corresponding surface thermodynamics equations are presented. The mechanical equilibrium equation at the surface is then obtained. It involves the surface stress and is similar to the Cauchy equation for the volume. Its normal component is a generalization of the Laplace equation. At a (body-fluid-fluid) triple contact line, two equations are obtained, which represent: (i) the equilibrium of the forces (surface stresses) for a triple line fixed on the body; (ii) the equilibrium relative to the motion of the line with respect to the body. This last equation leads to a strong modification of Young's classical capillary equation.

  3. Surface Wave Velocity-Stress Relationship in Uniaxially Loaded Concrete

    DEFF Research Database (Denmark)

    Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

    2012-01-01

    loading cycles revealed that the velocities show a stress-memory effect in good agreement with the Kaiser effect. Comparing the velocities measured during loading and unloading, the effects of stress and damage on the measured velocities could be differentiated. Moreover, the stress dependency of surface......The sonic surface wave (or Rayleigh wave) velocity measured on prismatic concrete specimens under uniaxial compression was found to be highly stress-dependent. At low stress levels, the acoustoelastic effect and the closure of existing microcracks results in a gradual increase in surface wave...... velocities. At higher stress levels, concrete suffers irrecoverable damage: the existing microcracks widen and coalesce and new microcracks form. This progressive damage process leads first to the flattening and eventually the drop in the velocity-stress curves. Measurements on specimens undergoing several...

  4. Comparison among four kinds of data of sea surface wind stress in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    谢强; 王卫强; 毛庆文

    2002-01-01

    By using remote sensing (ERS) data, FSU data, GOADS data and Hellerman & Rcsenstein objective analysis data to analyze the sea surface wind stress in the South China Sea, it is found that the remote sensing data have higher resolution and more reasonable values. Therefore we suggest that remote sensing data be chosen in the study of climatological features of sea surface wind stress and its seasonal variability in the South China Sea, especially in the study of small and middle scale eddies.

  5. WIND STRESS AND SURFACE ROUGHNESS AT AIR-SEA INTERFACE

    Science.gov (United States)

    Based on the compiled data of thirty independent observations, the report presents the wind - stress coefficient, the surface roughness and the...boundary layer flow regime at the air-sea interface under various wind conditions. Both the wind - stress coefficient and the surface roughness are found to...data and Charnock’s proportionality constant is determined. Finally, two approximate formulae for the wind - stress coefficient, one for light wind and the other for strong wind are suggested.

  6. Density functional theory calculations of the stress of oxidised (110) silicon surfaces

    CERN Document Server

    Melis, C; Colombo, L; Mana, G

    2016-01-01

    The measurement of the lattice-parameter of silicon by x-ray interferometry assumes the use of strain-free crystals. This might not be the case because surface relaxation, reconstruction, and oxidation cause strains without the application of any external force. In a previous work, this intrinsic strain was estimated by a finite element analysis, where the surface stress was modeled by an elastic membrane having a 1 N/m tensile strength. The present paper quantities the surface stress by a density functional theory calculation. We found a value exceeding the nominal value used, which potentially affects the measurement accuracy.

  7. Uniaxial Stress Dependence of the Fermi Surface of Copper.

    Science.gov (United States)

    Ruesink, Derk Willem

    Form a comprehensive experimental study of quantum oscillations in magnetostriction and torque, values have been deduced for all non-vanishing tetragonal and angular shear strain derivatives for the five principal extremal cross sections of the Fermi surface of copper, viz., the neck and belly normal to {111}, the dogsbone normal to {110} and the rosette and belly normal to {001}. It is found that the neck is most sensitive to angular shear strain, whereas the bellies are most affected by uniform dilation. For the other orbits the magnitudes of shear and dilation derivatives are comparable. The results are self consistent and agree with experimental tensile stress results of Shoenberg and Watts. Earlier magnetostriction results for the neck obtained by Aron and by Slavin can be brought into agreement with the present data by recalculating the former using the presently accepted value of the neck effective mass. The present experimental values are in reasonable agreement with theoretical values calculated by Lee, except for the tetragonal shear derivative of the {001} belly; the theoretical value is about 50% higher than the experimentally determined derivative.

  8. Residual stress around the cortical surface in bovine femoral diaphysis.

    Science.gov (United States)

    Yamada, Satoshi; Tadano, Shigeru

    2010-04-01

    Residual stress in living tissue plays an important role in mechanical strength. We have reported that residual stress exists in the bone tissue of a rabbit's tibiofibula. The purpose of this study is to measure the residual stress around the outer cortical region of bovine femoral diaphysis and to discuss the distribution of the stress. This work proposed the sin(2) psi method of X-ray diffraction to the measurement of residual stresses in bone tissue. In this method, residual stress can be estimated from the variation in the interplanar spacings orientated to a number of directions without the lattice strain in the stress direction. Four-point bending tests of strip specimens taken from bovine femoral diaphysis were carried out during X-ray irradiation in advance. In the proximal, middle, and distal sections of bovine femoral diaphyses, the residual stresses at the cortical surface were measured using characteristic Mo-Kalpha X-rays. The bending tests of strip specimens with X-ray irradiation showed that the method could reliably estimate residual stresses in the bone tissue. The residual stress of the bone axial direction was larger than that of the circumferential direction. The stresses in the middle part of five diaphyses along the bone axial direction were tensile. The maximum stress was 162 MPa at the lateral position and the minimum was 78 MPa at the posterior position. The residual stress in the bone axial direction varies around the circumferential region. In addition, the bone axial distributions of residual stresses were different in the proximal, middle, and distal sections of the individual femur. Furthermore, it was confirmed that residual stress in the bone tissue was released by the cutting out of the specimen. The residual stresses in bone tissue could be measured by this method. The results show that residual stress in the bone axial direction at the cortical surface in bovine femoral diaphysis is tensile and varies around the circumferential

  9. Temperature limit values for touching cold surfaces with the fingertip

    NARCIS (Netherlands)

    Geng, Q.; Holme, I.; Hartog, E.A. den; Havenith, G.; Jay, O.; Malchaires, J.; Piette, A.; Rintama, H.; Rissanen, S.

    2006-01-01

    Objectives: At the request of the European Commission and in the framework of the European Machinery Directive, research was performed in five different laboratories to develop specifications for surface temperature limit values for the short-term accidental touching of the fingertip with cold

  10. Temperature limit values for touching cold surfaces with the fingertip

    NARCIS (Netherlands)

    Geng, Q.; Holme, I.; Hartog, E.A. den; Havenith, G.; Jay, O.; Malchaires, J.; Piette, A.; Rintama, H.; Rissanen, S.

    2006-01-01

    Objectives: At the request of the European Commission and in the framework of the European Machinery Directive, research was performed in five different laboratories to develop specifications for surface temperature limit values for the short-term accidental touching of the fingertip with cold surfa

  11. Recommended values of clean metal surface work functions

    Energy Technology Data Exchange (ETDEWEB)

    Derry, Gregory N., E-mail: gderry@loyola.edu; Kern, Megan E.; Worth, Eli H. [Department of Physics, Loyola University Maryland, 4501 N. Charles St., Baltimore, Maryland 21210 (United States)

    2015-11-15

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  12. Near surface stress analysis strategies for axisymmetric fretting

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting is essentially a surface phenomenon, but bulk stresses and material properties contribute to subsequent failure. This feature of fretting demands a thorough understanding of near surface stresses under the joint action of normal, shear and thermal loading. Axisymmetric fretting is of great concern in piping and coupling design. In this paper, we develop design tools for Near Surface Analysis (NSA) for understanding axisymmetric fretting. Axisymmetric Fretting Analysis (AFA) becomes formidable owing to localised tractions that call for Fourier transform techniques. We develop two different NSA strategies based on two-dimensional plane strain models: 2D strip model (2DS) and half-plane Flamant model (2DF). We compare the results of 2DS and 2DF with the exact results for AFA obtained using Love’s stress function in conjunction with Fourier transform. There is a good correspondence between stress components obtained from 2D-models.

  13. Effect of dielectric coating on the electron work function and the surface stress of a metal

    Science.gov (United States)

    Babich, A. V.; Pogosov, V. V.

    2009-08-01

    The electron work function, contact potential difference, and surface stress of the elastically deformed faces of the metal covered by a dielectric are calculated by using the Kohn-Sham method and stabilized jellium model. Our calculations demonstrate the opposite deformation dependencies of the work function and contact potential difference. Dielectric coating leads to a negative change in the work function and a positive change in the contact potential difference. It is shown that the measurements of the contact potential difference of a deformed face by the Kelvin method give only the change in the value of the one-electron effective potential in the plane of a virtual image behind the surface, rather than the value of the electron work function. The obtained values of the electron work function and surface stress for Al, Au, Cu, and Zn are in agreement with the results of experiments for polycrystals.

  14. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

  15. Atomistic modelling of residual stress at UO2 surfaces.

    Science.gov (United States)

    Arayro, Jack; Tréglia, Guy; Ribeiro, Fabienne

    2016-01-13

    Modelling oxide surface behaviour is of both technological and fundamental interest. In particular, in the case of the UO2 system, which is of major importance in the nuclear industry, it is essential to account for the link between microstructure and macroscopic mechanical properties. Indeed micromechanical models at the mesoscale need to be supplied by the energetic and stress data calculated at the nanoscale. In this framework, we present a theoretical study, coupling an analytical model and thermostatistical simulation to investigate the modifications induced by the presence of a surface regarding atomic relaxation and energetic and stress profiles. In particular, we show that the surface effective thickness as well as the stress profile, which are required by micromechanical approaches, are strongly anisotropic.

  16. Discrimination between nuclear explosions and earthquakes based on consideration of tectonic ambient shear stress values

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On the basis of fracture mechanics earthquake rupture model, the relations between source parameters and t0, the value of tectonic ambient shear stress in the place where the earthquake occurs, have been derived. Thus, we can calculate a large number of values of tectonic ambient shear stress or values of background stress in the place where the earthquake occurs. If nuclear explosions are treated as earthquakes in the calculation, we find that t0 values of nuclear explosions have about 20 MPa, which is obviously higher than average t0 values of earthquakes with the same magnitude. This result can be used to discriminate nuclear explosions from earthquakes.

  17. 2D Gridded Surface Data Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Q [Lawrence Livermore National Laboratory; Xie, S [Lawrence Livermore National Laboratory

    2015-08-30

    This report describes the Atmospheric Radiation Measurement (ARM) Best Estimate (ARMBE) 2-dimensional (2D) gridded surface data (ARMBE2DGRID) value-added product. Spatial variability is critically important to many scientific studies, especially those that involve processes of great spatial variations at high temporal frequency (e.g., precipitation, clouds, radiation, etc.). High-density ARM sites deployed at the Southern Great Plains (SGP) allow us to observe the spatial patterns of variables of scientific interests. The upcoming megasite at SGP with its enhanced spatial density will facilitate the studies at even finer scales. Currently, however, data are reported only at individual site locations at different time resolutions for different datastreams. It is difficult for users to locate all the data they need and requires extra effort to synchronize the data. To address these problems, the ARMBE2DGRID value-added product merges key surface measurements at the ARM SGP sites and interpolates the data to a regular 2D grid to facilitate the data application.

  18. A comparison of tectonic ambient shear stress value in China with that in western USA

    Institute of Scientific and Technical Information of China (English)

    陈培善; 白彤霞; 李保昆

    2002-01-01

    A method is proposed to estimate average tectonic ambient shear stress value for a region. Thus the average stress values of 19 regions in western USA, and 43 regions (each region is 10((10() in Chinese mainland and its surroundings have been obtained. The data of 15 993 earthquakes are from the Internet Centroid Moment Tensor solution made by Harvard University from 1997 to 1999. The results demonstrate that there are highest average stress values in the regions of south California of USA and its off coast sea, reach to 12.0 MPa and 13.7 MPa respectively, then gradually decrease toward north, south, and east. The lowest value is 8.7 MPa and 63% of highest value. The average stress values in northern Xinjiang and in the Chayu region of Tibet are 17.2 and 12.9 MPa respectively. They are highest values in China and higher than USA(s. The average stress value in North China, Yunnan, Sichuan, Taiwan is similar to south California of USA. The average stress value in South-North seismic zone is about 13 MPa, a little higher than south California. The distribution of average stress value for two important regions provides basic data for geology. These results are useful to research earthquake activity background and attenuation relation of strong ground motion parameters (e.g. peak acceleration and response spectra).

  19. The stress-induced surface wave velocity variations in concrete

    Science.gov (United States)

    Spalvier, Agustin; Bittner, James; Evani, Sai Kalyan; Popovics, John S.

    2017-02-01

    This investigation studies the behavior of surface wave velocity in concrete specimens subjected to low levels of compressive and tensile stress in beams from applied flexural loads. Beam specimen is loaded in a 4-point-load bending configuration, generating uniaxial compression and tension stress fields at the top and bottom surfaces of the beam, respectively. Surface waves are generated through contactless air-coupled transducers and received through contact accelerometers. Results show a clear distinction in responses from compression and tension zones, where velocity increases in the former and decreases in the latter, with increasing load levels. These trends agree with existing acoustoelastic literature. Surface wave velocity tends to decrease more under tension than it tends to increase under compression, for equal load levels. It is observed that even at low stress levels, surface wave velocity is affected by acoustoelastic effects, coupled with plastic effects (stress-induced damage). The acoustoelastic effect is isolated by means of considering the Kaiser effect and by experimentally mitigating the viscoelastic effects of concrete. Results of this ongoing investigation contribute to the overall knowledge of the acoustoelastic behavior of concrete. Applications of this knowledge may include structural health monitoring of members under flexural loads, improved high order modelling of materials, and validation of results seen in dynamic acoustoelasticity testing.

  20. Determining Baseline Stress-Related Hormone Values in Large Cetaceans

    Science.gov (United States)

    2015-09-30

    stress hormone cortisol (N=1; 12 growth layers (GL)). This earplug was extracted from a shipstrike animal in 2007 (>1980s) and housed at the Santa...levels will be transformative for our understanding of the extent of exposure and the potential effect on the health of these animals and offers... exponential research opportunities that simply does not exist with traditional matrices such as blood and blubber and is ideally suited for examining

  1. REPLY: Reply to comment on 'Surface thermodynamics and surface stress for deformable bodies'

    Science.gov (United States)

    Olives, Juan

    2010-10-01

    The above comment and a previous letter by the same author reveal a great misunderstanding of what Eulerian and Lagrangian quantities are, and a confusion between the deformation of an element of a surface and the creation of a new element of a surface. Surface thermodynamics is complex because the surface quantities are not 'intuitive' (as surface excesses on some dividing surface) and the thermodynamic variables of the state of a surface are a priori completely unknown. This is why we introduced a new concept ('ideal transformation') and presented detailed proof, leading to the determination of the 'local' thermodynamic variables of the state of the surface, the exact expression of the work of deformation of the surface, and the definition of surface stress, for any deformable body (Olives 2010 J. Phys.: Condens. Matter 22 085005). These results are not obvious (despite their similarity with some expressions in volume thermodynamics). We explicitly write the Eulerian forms of (i) the relation between the surface grand potential per unit area, the surface stress and the surface strain, showing its exact equivalence with the Lagrangian form, and (ii) the variation of the surface energy due to both the deformation of an element of the surface and the creation of a new element of the surface.

  2. INTERFACE DEVICE FOR NONDESTRUCTIVE TESTING OF RESIDUAL SURFACE STRESSES

    Directory of Open Access Journals (Sweden)

    Gennady A. Perepelkin

    2016-01-01

    Full Text Available The paper considers the organization of connection of a personal computer with a device for nondestructive testing of residual surface stresses. The device works is based on the phenomenon of diffraction of ionizing radiation from the crystal lattice near the surface of the crystallites. Proposed software interface to the organization for each type of user: the device developers, administrators, users. Some aspects of the organization of communication microcontroller to a PC via USB-port

  3. Diffraction analysis of nonuniform stresses in surface layers : Application to cracked TiN coatings chemically vapor deposited on Mo

    NARCIS (Netherlands)

    Sloof, W.G.; Kooi, B.J.; Delhez, R.; Keijser, Th.H. de; Mittemeijer, E.J.

    1996-01-01

    Variations of residual stresses in layers on substrates can occur in directions parallel and perpendicular to the surface as a result of compositional inhomogeneity and/or porosity or cracks. Diffraction methods to evaluate such stress variations are presented. Comparison of the experimental value f

  4. Station-based Surface Data Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Q. [DOE ARM Climate Research Facility, Washington, DC (United States); Xie, S. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    This report describes the Atmospheric Radiation Measurement (ARM) Best Estimate (ARMBE) station-based surface data (ARMBESTNS) value-added product. It is a twin data product of the ARMBE 2-Dimensional gridded (ARMBE2DGRID) data set. Unlike the ARMBE2DGRID data set, ARMBESTNS data are reported at the original site locations and show the original information (except for the interpolation over time). Therefore, the users have the flexibility to process the data with the approach more suitable for their applications. This document provides information about the input data, quality control (QC) method, and output format of this data set. As much of the information is identical to that of the ARMBE2DGRID data, this document will emphasize more on the different aspects of these two data sets.

  5. Interaction of stress and phase transformations during thermochemical surface engineering

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard

    Low temperature nitriding of austenitic stainless steel causes a surface zone of expanded austenite, which improves the wear resistance of the stainless steel while preserving the stainless behavior. During nitriding huge residual stresses are introduced in the treated zone, arising from the volume...... expansion that accompanies the dissolution of high nitrogen contents in expanded austenite. An intriguing phenomenon during low-temperature nitriding, is that the residual stresses evoked by dissolution of nitrogen in the solid state, affect the thermodynamics and the diffusion kinetics of nitrogen...... dissolution. The present project is devoted to understanding the mutual interaction of stresses and phase transformations during thermochemical surface engineering by combining numerical modelling with experimental materials science. The modelling was done by combining solid mechanics with thermodynamics...

  6. A micromachined surface stress sensor with electronic readout

    NARCIS (Netherlands)

    Carlen, E.T.; Weinberg, M.S.; Zapata, A.M.; Borenstein, J.T.

    2008-01-01

    A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and filt

  7. Cantilever surface stress sensors with single-crystalline silicon piezoresistors

    DEFF Research Database (Denmark)

    Rasmussen, Peter Andreas; Hansen, Ole; Boisen, Anja

    2005-01-01

    on cantilever sensors with integrated piezoresistive readout, that one finds between typical atomic force microscopy measurements and the surface stress sensors used in, e.g., biochemical measurements. We have simulated the response from piezoresistive cantilevers as a function of resistor type and placement...

  8. Stress analysis and stress-intensity factors for finite geometry solids containing rectangular surface cracks

    Science.gov (United States)

    Gyekenyesi, J. P.; Mendelson, A.

    1977-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses, and the stress-intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress-intensity factors are also obtained for a through-thickness, center-cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress-intensity factors for commonly encountered surface crack geometries in finite solids

  9. Stress analysis and stress intensity factors for finite geometry solids containing rectangular surface cracks

    Science.gov (United States)

    Gyekenyesi, J. P.; Mendelson, A.

    1975-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses and the stress intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress intensity factors are also obtained for a through-thickness, center cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress intensity factors for commonly encountered surface crack geometries in finite solids.

  10. Theoretical modeling and experimental validation of surface stress in thrombin aptasensor.

    Science.gov (United States)

    Lim, Yang Choon; Kouzani, Abbas Z; Kaynak, Akif; Dai, Xiujuan J; Littlefair, Guy; Duan, Wei

    2014-12-01

    Adsorption of target molecules on the immobilized microcantilever surface produced beam displacement due to the differential surface stress generated between the immobilized and non-immobilized surface. Surface stress is caused by the intermolecular forces between the molecules. Van der Waals, electrostatic forces, hydrogen bonding, hydrophobic effect and steric hindrance are some of the intermolecular forces involved. A theoretical framework describing the adsorption-induced microcantilever displacement is derived in this paper. Experimental displacement of thrombin aptamer-thrombin interactions was carried out. The relation between the electrostatic interactions involved between adsorbates (thrombin) as well as adsorbates and substrates (thrombin aptamer) and the microcantilever beam displacement utilizing the proposed mathematical model was quantified and compared to the experimental value. This exercise is important to aid the designers in microcantilever sensing performance optimization.

  11. Surface micromachined differential piezoelectric shear-stress sensors

    Science.gov (United States)

    Williams, Randall P.; Kim, Donghwan; Gawalt, David P.; Hall, Neal A.

    2017-01-01

    The ability to measure viscous wall shear stress in high-speed flows is important for verifying simulated results typically obtained from direct numerical simulation in the aerodynamics research community, and robust sensors are required to measure wall shear reliably under such high-speed conditions. This letter summarizes the design, fabrication, and testing of a surface micromachined piezoelectric shear-stress sensor which uses a thin piezoelectric film to generate a voltage proportional to an applied shear stress without additional moving parts. A differential-cell architecture is used to enhance selectivity to shear stress while canceling normal-stress sensitivity. The conceptual design, fabrication details, and experimental measurements of device sensitivity are presented. A finite element model is used to validate the device performance against measurements, and to provide insight into the potential and electric fields underlying the device concept. The potential for understanding device behavior and optimization through modeling is illustrated using finite element analysis results. The minimum detectable shear stress for the sensor is estimated to be 52.9 mPa  √Hz-1 at 1.5 kHz.

  12. Effect of temperature-dependent surface heat transfer coefficient on the maximum surface stress in ceramics during quenching

    Science.gov (United States)

    Shao, Y. F.; Song, F.; Jiang, C. P.; Xu, X. H.; Wei, J. C.; Zhou, Z. L.

    2016-02-01

    We study the difference in the maximum stress on a cylinder surface σmax using the measured surface heat transfer coefficient hm instead of its average value ha during quenching. In the quenching temperatures of 200, 300, 400, 500, 600 and 800°C, the maximum surface stress σmmax calculated by hm is always smaller than σamax calculated by ha, except in the case of 800°C; while the time to reach σmax calculated by hm (fmmax) is always earlier than that by ha (famax). It is inconsistent with the traditional view that σmax increases with increasing Biot number and the time to reach σmax decreases with increasing Biot number. Other temperature-dependent properties also have a small effect on the trend of their mutual ratios with quenching temperatures. Such a difference between the two maximum surface stresses is caused by the dramatic variation of hm with temperature, which needs to be considered in engineering analysis.

  13. Prognostic value of dobutamine-atropine stress myocardial perfusion imaging in patients with diabetes

    NARCIS (Netherlands)

    A.F.L. Schinkel (Arend); A. Elhendy (Abdou); J.J. Bax (Jeroen); E.C. Vourvouri (Eleni); F. Sozzi (Fabiola); R. Valkema (Roelf); D. Poldermans (Don); J.R.T.C. Roelandt (Jos); R.T. van Domburg (Ron)

    2002-01-01

    textabstractOBJECTIVE: Exercise tolerance in patients with diabetes is frequently impaired due to noncardiac disease such as claudication and polyneuropathy. This study assesses the prognostic value of dobutamine stress myocardial perfusion imaging in patients with diabetes. RESEAR

  14. Prognostic and diagnostic value of moderate intensity stress test with blood pressure control

    Directory of Open Access Journals (Sweden)

    V. N. Marchenko

    2014-01-01

    Full Text Available In spite of age and blood pressure values at rest,hypertensive response to moderate intensity stress testingis characterized by increasing ofprobable beginning of cardiac infarction, stroke or coronary disease in 1.36 times. The hypertensive response to stress test in people with normal blood pressure values at rest (independent of other risk factors is characterized by increasing risk of future hypertension more than in 2 times. Antihypertensive drugs affect blood pressure values differently during the stress testing. The prognosis of blood pressure values during daily physical activity is necessary for antihypertensive treatment. Low availability of convenient instruments and methodological tools for continuous measurement of blood pressure (similar to Spiroarteriocardiorhythmograph, Finapres duringthe dosed physical loads constrain wide use of stress tests with controlled blood pressure in medical practice.

  15. Nanoscale patterning, macroscopic reconstruction, and enhanced surface stress by organic adsorption on vicinal surfaces

    Science.gov (United States)

    Pollinger, Florian; Schmitt, Stefan; Sander, Dirk; Tian, Zhen; Kirschner, Jürgen; Vrdoljak, Pavo; Stadler, Christoph; Maier, Florian; Marchetto, Helder; Schmidt, Thomas; Schöll, Achim; Umbach, Eberhard

    2017-01-01

    Self-organization is a promising method within the framework of bottom-up architectures to generate nanostructures in an efficient way. The present work demonstrates that self-organization on the length scale of a few to several tens of nanometers can be achieved by a proper combination of a large (organic) molecule and a vicinal metal surface if the local bonding of the molecule on steps is significantly stronger than that on low-index surfaces. In this case thermal annealing may lead to large mass transport of the subjacent substrate atoms such that nanometer-wide and micrometer-long molecular stripes or other patterns are being formed on high-index planes. The formation of these patterns can be controlled by the initial surface orientation and adsorbate coverage. The patterns arrange self-organized in regular arrays by repulsive mechanical interactions over long distances accompanied by a significant enhancement of surface stress. We demonstrate this effect using the planar organic molecule PTCDA as adsorbate and Ag(10 8 7) and Ag(775) surfaces as substrate. The patterns are directly observed by STM, the formation of vicinal surfaces is monitored by high-resolution electron diffraction, the microscopic surface morphology changes are followed by spectro-microscopy, and the macroscopic changes of surface stress are measured by a cantilever bending method. The in situ combination of these complementary techniques provides compelling evidence for elastic interaction and a significant stress contribution to long-range order and nanopattern formation.

  16. Accurate computation of surface stresses and forces with immersed boundary methods

    CERN Document Server

    Goza, Andres; Morley, Benjamin; Colonius, Tim

    2016-01-01

    Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is a...

  17. Influence of surface stressing on stellar coronae and winds

    CERN Document Server

    Jardine, M; van Ballegooijen, A; Donati, J -F; Morin, J; Fares, R; Gombosi, T I

    2013-01-01

    The large-scale field of the Sun is well represented by its lowest energy (or potential) state. Recent observations, by comparison, reveal that many solar-type stars show large-scale surface magnetic fields that are highly non-potential - that is, they have been stressed above their lowest-energy state. This non-potential component of the surface field is neglected by current stellar wind models. The aim of this paper is to determine its effect on the coronal structure and wind. We use Zeeman-Doppler surface magnetograms of two stars - one with an almost potential, one with a non-potential surface field - to extrapolate a static model of the coronal structure for each star. We find that the stresses are carried almost exclusively in a band of uni-directional azimuthal field that is confined to mid-latitudes. Using this static solution as an initial state for an MHD wind model, we then find that the final state is determined primarily by the potential component of the surface magnetic field. The band of azimut...

  18. Refraction of the principal stress trajectories at a surface of discontinuity and related problems

    Science.gov (United States)

    Mukhamediev, Shamil

    2014-05-01

    can be presented by the stress orientation sphere which is divided into 3 pairs of areas: tension, compression and compression-tension. Tension areas can not contain poles of the T3 axes whereas poles of the T1 axes are prohibited for the compression areas. The areas of compression-tension, which are spherical digons with angle ϕ-, may contain the T1 or T3 pole but not both poles simultaneously. In some particular cases, when the vector p- has a unique direction (ϕ-=0), the compression-tension digons disappear and the stress orientation sphere degenerates into a "beach ball" diagram which is characteristic for the earthquake focal mechanism solutions. If the potentially compatible pairs of the T1 and T3 axes are given, then the jumps of the stress values across the surface D can be easily calculated. The results obtained have a wide range of applications. For example, no trihedron of the principal stress axes can be associated with a slip along already existing fault. In fact, 6 values are to be determined. These values define orientation of the potentially compatible stress axes on both sides of the fault. Existing restrictions are too weak to ensure that these values can be determined locally.

  19. EFFECT OF TENSILE STRESS AND RESIDUAL STRESS ON THE SPONTANEOUS STRAY FIELD SIGNALS FROM THE SURFACE OF 0.45%C STEEL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to explore the quantitative method of metal magnetic memory testing(MMMT) and clarify the relationship between Hp(y), the normal component of spontaneous stray field, and applied stress or residual stress, the static tensile tests of 0.45%C steel sheet specimens are carried out on a servo hydraulic MTS810 machine. Hp(y) values are measured during the test process by an EMS-2003 metal magnetic memory diagnostic apparatus and a non-magnetic electric control displacement instrument. Residual stresses of some points on the surface of a specimen are measured by a Stress Tech X-Stress 3000 X-ray diffraction instrument. The results show that the same variation rules of Hp(y) value versus applied tensile stress are presented under the different conditions of load-on and load-off. However, the same rule does not exist between the Hp(y) value and residual stress. The variation of Hp(y) value reflects the history of applied tensile stress.

  20. Morphology, stresses, and surface reactivity of nanoporous gold synthesized from nanostructured precursor alloys

    Science.gov (United States)

    Rouya, Eric

    , and finally remains tensile over longer times. An increase in Ni content overall resulted in (i) an increase in maximum compressive stress, (ii) a decrease in compressive-to-tensile transition thickness, and (iii) an increase in steady-state tensile stress. The stress profile recorded in situ during Au-Ni and Au-Ag dealloying exhibits an initial rise in tensile stress followed by a steady-state compressive stress over longer times. The former is due to void formation, while the latter is indicative of a stress relaxation mechanism, which may occur either via cracking, a consequence tensile stress build-up from the dissolution of the more reactive alloy component, and/or Au atom clustering, which reduces the curvature of Au ligaments and hence coarsens the overall NPG surface. Up to 55% and 71% stress relaxation were measured for dealloyed Au-Ni and Au-Ag, respectively. Au oxidation can additionally inhibit tensile stress relaxation by kinetically hindering Au atom diffusivity, further contributing to a structurally unstable NPG film. The surface area (SA) of NPG films was quantified using Cu underpotential deposition (UPD), Au oxidation, electrochemical impedance spectroscopy (EIS), and Ag UPD. While the SA was found to increase linearly with NPG thickness, the EIS-based values were larger than those determined from Cu UPD and Au oxidation by ˜60%. This discrepancy was ascribed partly to the presence of residual Ag atoms on the NPG surface, which act to inhibit Cu reduction and Au oxidation. The EIS probes the entire NPG surface irrespective of surface chemistry, as supported by the negligible change in SA when NPG was additionally modified with UPD Ag. An electrocatalysis study revealed a de-polarization in the ORR, and therefore an enhancement in the electrocatalytic activity of NPG relative to planar Au. This is consistent with NPG's activity towards the reduction of a H2O2 intermediate, whereas planar Au only partially reduces O2 to H2O2. Modification of NPG with

  1. Linear and nonlinear modulus surfaces in stress space, from stress-strain measurements on Berea sandstone

    Directory of Open Access Journals (Sweden)

    M. Boudjema

    2003-01-01

    Full Text Available The elastic response of many rocks to quasistatic stress changes is highly nonlinear and hysteretic, displaying discrete memory. Rocks also display unusual nonlinear response to dynamic stress changes. A model to describe the elastic behavior of rocks and other consolidated materials is called the Preisach-Mayergoyz (PM space model. In contrast to the traditional analytic approach to stress-strain, the PM space picture establishes a relationship between the quasistatic data and a number density of hysteretic mesoscopic elastic elements in the rock. The number density allows us to make quantitative predictions of dynamic elastic properties. Using the PM space model, we analyze a complex suite of quasistatic stress-strain data taken on Berea sandstone. We predict a dynamic bulk modulus and a dynamic shear modulus surface as a function of mean stress and shear stress. Our predictions for the dynamic moduli compare favorably to moduli derived from time of flight measurements. We derive a set of nonlinear elastic constants and a set of constants that describe the hysteretic behavior of the sandstone.

  2. Local protrusions formed on Si(111) surface by surface melting and solidification under applied tensile stress

    Science.gov (United States)

    Nishimura, T.; Tomitori, M.

    2016-09-01

    The surface structure and composition of Si(111) was modified, by heating it to 1300 °C in ultrahigh vacuum under an external tensile stress. A stress of approximately 1 GPa was applied, by pressing on the center of the rear side of the sample. This process produced two protrusions of approximately 100 μm in height, to the left and right of the center. Scanning Auger electron spectroscopy revealed Fe, Cr, Ni, and C impurities at the top of one protrusion, and C at the top of the other. These impurities likely diffused into the tops of the protrusions during heating, and segregated to the local surface during cooling when the protrusions formed. The protrusion formation mechanism is discussed. Their formation was related to non-uniform surface temperature, electromigration, piezoresistivity, freezing-point depression due to surface alloying with the impurities, and volume expansion during solidification from surface melting. These findings provide a perspective on controlling surface structures and compositions using heat and stress to induce self-assembly.

  3. Predicting temperature timit values for cold touchable surfaces

    NARCIS (Netherlands)

    Hartog, E.A. den

    2005-01-01

    During some occupational activities, workers have to handle objects or tools in cold environments. In other circumstances, contact between the hand and the cold surface might be accidental (e.g., when a worker touches a cold surface, a cooler, etc). In both cases, contact between the hands and the c

  4. Surface Residual Stresses in Ti-6Al-4V Friction Stir Welds: Pre- and Post-Thermal Stress Relief

    Science.gov (United States)

    Edwards, P.; Ramulu, M.

    2015-09-01

    The purpose of this study was to determine the residual stresses present in titanium friction stir welds and if a post-weld thermal stress relief cycle would be effective in minimizing those weld-induced residual stresses. Surface residual stresses in titanium 6Al-4V alloy friction stir welds were measured in butt joint thicknesses ranging from 3 to 12 mm. The residual stress states were also evaluated after the welds were subjected to a post-weld thermal stress relief cycle of 760 °C for 45 min. High (300-400 MPa) tensile residual stresses were observed in the longitudinal direction prior to stress relief and compressive residual stresses were measured in the transverse direction. After stress relief, the residual stresses were decreased by an order of magnitude to negligible levels.

  5. Stress response and the value of reproduction: are birds prudent parents?

    Science.gov (United States)

    Bókony, Veronika; Lendvai, Adám Z; Liker, András; Angelier, Frédéric; Wingfield, John C; Chastel, Olivier

    2009-05-01

    In vertebrates, stressors such as starvation or predator attacks stimulate the rapid elevation of circulating glucocorticoid hormones, triggering physiological and behavioral responses that aid immediate survival but simultaneously inhibit reproduction. This stress response has been proposed to serve as a physiological mediator of life-history trade-offs: when the value of current reproduction is high relative to the value of future reproduction and survival, a mitigated stress response is expected to enable successful breeding and maximize fitness. Using phylogenetic comparative analyses, we investigated baseline and peak stress-induced plasma corticosterone levels during parental care in 64 bird species. We found that (1) species with a higher value of the current brood relative to future breeding mounted weaker corticosterone responses during acute stress, and (2) females in species with more female-biased parental care had weaker corticosterone responses. These results support the brood value hypothesis, suggesting that the stress response evolves as an adaptive basis for life-history strategies. Further, we found that (3) baseline corticosterone correlated positively with brood value and negatively with body mass, and (4) peak corticosterone was greater in species breeding at higher latitudes. The latter findings suggest that circulating corticosterone concentrations might be matched to the anticipated demands and risks during nesting.

  6. Mechanism of preventing coal and gas compression disseminated values outburst with stress pre-released hydraulically

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhong-fei; Yu, Qi-xiang [Jiangsu University, Zhenjiang (China). Center of Safety Engineering

    2007-01-15

    Based on the conditions of coal and gas outburst, the action mechanism for preventing coal and gas compression disseminated values outburst with stress pre-released hydraulically was analyzed. The accuracy of this mechanism was validated by measuring the gas emission before and after pre-releasing stress hydraulically, measuring the rupture failure by the electromagnetic radiation technique and the correlative practical datum. The results show that the electromagnetic radiation intensity and pulse count are increscent when taking the measure of stress pre-released hydraulically, which is propitious to prevent the coal and gas outburst. The action mechanism consists of three aspects: 1) Pre-releasing gas and increasing tangential stress and disseminated values friction resistance; 2) Pre-releaseing the radial effective geostress on high-tension side and reducing the radial stress difference of disseminated values chop motion for enhancing coal displacement; 3) Making the disseminated values and adjacent coal and rock felting by flooding water and increasing the disseminated values' friction resistance coefficients. 9 refs., 2 figs.

  7. Mechanical Values Transformer on the Surface Acoustic Waves

    Directory of Open Access Journals (Sweden)

    V. O. Piddubnyi

    2008-05-01

    Full Text Available Calculation of parameters of the membrane type mechanical values transformer into the frequency electric signal is rewired. The article deals with the issues of deformational and heat sensitivity. Results of research are shown.

  8. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Science.gov (United States)

    Ghorbanpour Arani, A.; Roudbari, M. A.

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler-Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  9. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Roudbari, M.A. [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of)

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler–Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  10. Stress vs sputtering effects in the propagation of surface ripples produced by ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Barrado, A. [Instituto de Investigación Tecnológica (IIT) and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Pontificia Comillas, E-28015 Madrid (Spain); Castro, M. [GISC and Grupo de Dinámica No Lineal (DNL), Escuela Técnica Superior de Ingeniería (ICAI), Universidad Pontificia Comillas, E-28015 Madrid (Spain); Muñoz-García, J. [Departamento de Matemáticas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganés (Spain); Cuerno, R., E-mail: cuerno@math.uc3m.es [Departamento de Matemáticas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganés (Spain)

    2015-12-15

    Under low energy ion irradiation, periodic features (ripples) can develop on the surfaces of semiconductor materials, with typical sizes in the nanometric range. Recently, a theory of pattern formation has been able to account for the variability with the ion/target combination of the critical angle value separating conditions on ion incidence that induce the presence or the absence of ripples. Such a theory is based in the accumulation of stress in the damaged irradiated layer and its relaxation via surface-confined viscous flow. Here we explore the role of stress, and its competition with purely erosive mechanisms, to determine the sign of the velocity with which the ripple pattern moves across the target plane. Based on this theory, we discuss different situations and make specific testable predictions for the change of sign in that velocity.

  11. A Mean Value Theorem for Closed Geodesics on Congruence Surfaces

    OpenAIRE

    Lukianov, Vladimir

    2005-01-01

    We define a weighted multiplicity function for closed geodesics of given length on a finite area Riemann surface. These weighted multiplicities appear naturally in the Selberg trace formula, and in particular their mean square plays an important role in the study of statistics of the eigenvalues of the Laplacian on the surface. In the case of the modular domain, E. Bogomolny, F. Leyvraz and C. Schmit gave a formula for the mean square, which was rigorously proved by M. Peter. In this paper we...

  12. Racial-ethnic disparities in maternal parenting stress: the role of structural disadvantages and parenting values.

    Science.gov (United States)

    Nomaguchi, Kei; House, Amanda N

    2013-01-01

    Although researchers contend that racial-ethnic minorities experience more stress than whites, knowledge of racial-ethnic disparities in parenting stress is limited. Using a pooled time-series analysis of data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (n = 11,324), we examine racial-ethnic differences in maternal parenting stress, with a focus on structural and cultural explanations and variations by nativity and child age. In kindergarten, black mothers, albeit U.S.-born only, report more parenting stress than white mothers due to structural disadvantages and authoritarian parenting values. The black-white gap increases from kindergarten to third grade, and in third grade, U.S.-born black mothers' higher stress than white mothers' persists after controlling for structural and parenting factors. Hispanic and Asian mothers, albeit foreign-born only, report more stress than white mothers at both ages due to structural disadvantages and authoritarian values. Despite structural disadvantages, American Indian mothers report less stress.

  13. Surface properties and exponential stress relaxations of mammalian meibum films.

    Science.gov (United States)

    Eftimov, Petar; Yokoi, Norihiko; Tonchev, Vesselin; Nencheva, Yana; Georgiev, Georgi As

    2017-03-01

    The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ  100 s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25 °C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

  14. Analytical Modeling of Surface Roughness, Hardness and Residual Stress Induced by Deep Rolling

    Science.gov (United States)

    Magalhães, Frederico C.; Abrão, Alexandre M.; Denkena, Berend; Breidenstein, Bernd; Mörke, Tobias

    2016-12-01

    Deep rolling is a mechanical surface treatment that can significantly alter the features of metallic components and despite the fact that it has been used for a long time, to date the influence of the interaction among the principal process parameters has not been thoroughly understood. Aiming to fulfill this gap, this work addresses the effect of deep rolling on surface finish and mechanical properties from the analytical and experimental viewpoints. More specifically, the influence of deep rolling pressure and number of passes on surface roughness, hardness and residual stress induced on AISI 1060 steel is investigated. The findings indicate that the surface roughness after deep rolling is closely related to the yield strength of the work material and the available models can satisfactorily predict the former parameter. Better agreement between the mathematical and experimental hardness values is achieved when a single deep rolling pass is employed, as well as when the yield strength of the work material increases. Compressive residual stress is generally induced after deep rolling, irrespectively of the selected heat treatment and deep rolling parameters. Finally, the model proposed to predict residual stress provides results closest to the experimental data especially when the annealed material is considered.

  15. Weight Function Method for Stress Intensity Factor of Internal Surface Semi-elliptical Crack in Elliptical Holes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hatches for inspecting are usually designed with elliptical holes in airplane structures, so computation of the stress intensity factor of three dimensional crack at elliptical holes is pivotal for damage tolerance analysis of these structures. In this paper, weight function is derived for a two dimensional through cracks at elliptical holes by applying a compounding method. Stress intensity factor formulas for an internal surface semi-elliptical crack in elliptical holes are obtained using the three dimensional weight function method. Stress intensity factors for an internal surface semi-elliptical crack in elliptical holes under remote tension are computed. At the same time, research on how radius of curvature for elliptical holes affect stress intensity factors was conducted. Stress intensity factors decrease when radius of curvature increases. Some results and conclusions which are of practical value are given.

  16. Finite Element Surface Layer Inheritable Condition Residual Stresses Model in Surface Plastic Deformation Processes

    Science.gov (United States)

    Mahalov, M. S.; Blumenstein, V. Yu

    2016-04-01

    The residual stresses (RS) research and computational algorithms creation in complex types of loading on the product lifecycle stages relevance is shown. The RS forming finite element model at surface plastic deformation strengthening machining, including technological inheritance effect, is presented. A model feature is the production previous stages obtained transformation properties consideration, as well as these properties evolution during metal particles displacement through the deformation space in the present loading step.

  17. LIMIT BEHAVIOUR OF SOLUTIONS TO EQUIVALUED SURFACE BOUNDARY VALUE PROBLEM FOR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    LI Fengquan

    2002-01-01

    In this paper, we discuss the limit behaviour of solutions to equivalued surface boundary value problem for parabolic equations when the equivalued surface boundary shrinks to a point and the space dimension of the domain is two or more.

  18. On the totally ramified value number of the Gauss map of minimal surfaces

    OpenAIRE

    Kawakami, Yu

    2006-01-01

    In this paper, we define the totally ramified value number (TRVN) of the Gauss map of a complete minimal surface, and prove that there exist algebraic minimal surfaces that have the TRVN equal to $2.5$.

  19. LIMIT BEHAVIOUR OF SOLUTIONS TO EQUIVALUED SURFACE BOUNDARY VALUE PROBLEM FOR PARABOLIC EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    LiFengquan

    2002-01-01

    In this paper,we discuss the limit behaviour of solutions to equivalued surface boundayr value problem for parabolic equatiopns when the equivalued surface boundary shriks to a point and the space dimension of the domain is two or more.

  20. Effect of initial stress on reflection at the free surface of anisotropic elastic medium

    Indian Academy of Sciences (India)

    M D Sharma

    2007-12-01

    The propagation of plane waves is considered in a general anisotropic elastic medium in the presence of initial stress. The Christoffel equations are solved into a polynomial of degree six. The roots of this polynomial represent the vertical slowness values for the six quasi-waves resulting from the presence of a discontinuity in the medium. Three of these six values are identified with the three quasi-waves traveling in the medium but away from its boundary. Reflection at the free plane surface is studied for partition of energy among the three reflected waves. For post-critical incidence, the reflected waves are inhomogeneous (evanescent) waves. Numerical examples are considered to exhibit the effects of initial stress on the phase direction, attenuation and reflection coefficients of the reflected waves. The phase velocities and energy shares of the reflected waves change significantly with initial stress as well as anisotropic symmetry. The presence of initial stress, however, has a negligible effect on the phase directions of reflected waves.

  1. Predischarge stress test after myocardial infarction in the old stage : results and prognostic value

    NARCIS (Netherlands)

    P.M. Fioretti (Paolo); J.W. Deckers (Jaap); R.W. Brower (Ronald); M.L. Simoons (Maarten); J.A.J.M. Beelen; P.G. Hugenholtz (Paul)

    1984-01-01

    textabstractThe aim of this study was to evaluate the results of predischarge stress testing in the elderly, and to assess the prognostic value of the test during one-year follow-up. The database consisted of 48 patients older than 64 years of age and 109 patients 55-64 years of age, who survived ac

  2. Deposition of Low Stress Silicon Nitride Thin Film and Its Application in Surface Micromachining Device Structures

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available Surface machining processes are responsible for creating microstructures that reside near the surfaces of a substrate and are characterized by the fabrication of micromechanical structures from deposited thin films. These films can be selectively removed to build three-dimensional structures whose functionality typically requires that they should be freed from the planar substrate. Silicon nitride thin film is one of these important materials. In this paper, by adjusting the SiH2Cl2/NH3 gaseous ratio, low stress silicon nitride (LS SiN is deposited by the low pressure chemical vapor deposition (LPCVD process. The internal stress generally in 135 MPa has been detected using an FLX-2320 film stress tester. Based on the wide application in surface micromachining devices, the mechanical properties of LS SiN are measured by nanoindentation, giving the value of Young’s modulus of 224 GPa and the hardness of 22.5 GPa, respectively. Dry etching and wet etching are utilized to fabricate the LS SiN thin film for structural layers. The etching rate compared with normal Si3N4 film by LPCVD is demonstrated for silicon chip manufacture.

  3. Water stress indices for the sugarcane crop on different irrigated surfaces

    Directory of Open Access Journals (Sweden)

    Rodrigo G. Brunini

    Full Text Available ABSTRACT Sugarcane (Saccharum officinarum L. is a crop of vital importance to Brazil, in the production of sugar and ethanol, power generation and raw materials for various purposes. Strategic information such as topography and canopy temperature can provide management technologies accessible to farmers. The objective of this study was to determine water stress indices for sugarcane in irrigated areas, with different exposures and slopes. The daily water stress index of the plants and the water potential in the soil were evaluated and the production system was analyzed. The experiment was carried out in an “Experimental Watershed”, using six surfaces, two horizontal and the other ones with 20 and 40% North and South exposure slopes. Water stress level was determined by measuring the temperatures of the vegetation cover and the ambient air. Watering was carried out using a drip irrigation system. The results showed that water stress index of sugarcane varies according to exposure and slope of the terrain, while areas whose water stress index was above 5.0 oC had lower yield values.

  4. The impact of drought stress on the yields and food value of selected forage grasses

    Directory of Open Access Journals (Sweden)

    Mariola Staniak

    2016-06-01

    Full Text Available The aim of the study was to compare yields and nutritional value of selected species and cultivars of forage grasses under the optimal moisture conditions and long-term drought stress. The regenerative capacity of plants after dehydration was also assessed. The pot experiment was conducted in years 2009–2010 in IUNG-PIB’s greenhouse in Puławy, Poland. Nine cultivars of four species: Dactylis glomerata (‘Amera’, ‘Minora’, Festuca pratensis (‘Skra’, ‘Fantazja’, Festulolium braunii (‘Felopa’, ‘Agula’, ‘Sulino’, and Lolium multiflorum (‘Gisel’, ‘Lotos’ were investigated in well-watered conditions (70% field water capacity – FWC and under a long-term drought stress (40% FWC. The study showed that stress caused by soil moisture deficiency significantly reduced yields of D. glomerata, F. pratensis, F. braunii, and L. multiflorum. The total yield of dry matter under stress conditions was about 31% lower, compared to the performance achieved on the optimally moisturized treatment. The smallest reduction in dry matter yield under the conditions of water deficit was recorded for D. glomerata, which makes it the most resistant to stress, followed by F. pratensis. The resistance of F. braunii and L. multiflorum to stress was similar and significantly lower. There was a various response of different grasses to the water stress. On the basis of the value of the DSI (drought susceptibility index, the tested cultivars were ranked depending on the sensitivity to drought, starting with the most resistant cultivar: ‘Minora’, ‘Skra’, ‘Fantazja’, ‘Amera’, ‘Sulino’, ‘Agula’, ‘Gisel’, ‘Lotos’, and ‘Felopa’. The digestibility of dry matter and nutrient value of the grasses depended on both the level of soil moisture and grass species. Under the water stress, the digestibility and protein value increased compared to the control objects. Lolium multiflorum and F. braunii had the best

  5. Accurate computation of surface stresses and forces with immersed boundary methods

    Science.gov (United States)

    Goza, Andres; Liska, Sebastian; Morley, Benjamin; Colonius, Tim

    2016-09-01

    Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is applied as a post-processing procedure, so that the convergence of the velocity field is unaffected. We demonstrate the efficacy of the method by computing stresses and forces that converge to the physical stresses and forces for several test problems.

  6. Evaluation of Tire/Surfacing/Base Contact Stresses and Texture Depth

    Directory of Open Access Journals (Sweden)

    W.J.vdM. Steyn

    2015-03-01

    Full Text Available Tire rolling resistance has a major impact on vehicle fuel consumption. Rolling resistance is the loss of energy due to the interaction between the tire and the pavement surface. This interaction is a complicated combination of stresses and strains which depend on both tire and pavement related factors. These include vehicle speed, vehicle weight, tire material and type, road camber, tire inflation pressure, pavement surfacing texture etc. In this paper the relationship between pavement surface texture depth and tire/surfacing contact stress and area is investigated. Texture depth and tire/surfacing contact stress were measured for a range of tire inflation pressures on five different pavement surfaces. In the analysis the relationship between texture and the generated contact stresses as well as the contact stress between the surfacing and base layer are presented and discussed, and the anticipated effect of these relationships on the rolling resistance of vehicles on the surfacings, and subsequent vehicle fuel economy discussed.

  7. Wrinkling vs. scarring: Stress collapse in surface-confined assemblies

    Science.gov (United States)

    Grason, Gregory

    2014-03-01

    Confining assemblies to surfaces possessing Gaussian curvature frustrates the microscopic order of the packing, thus introducing mechanical costs for assemblies in such diverse contexts as viral capsids and particle-coated drops. The structure and stability of these systems is complicated by the non-trivial competition between distinct modes of stress relaxation, including ``elastic'' shape deformation of the surface-bound assembly; defect-mediated ``plastic'' reorganization of packing. We consider the interplay between these shape-deformation and defect-relaxation for a model of crystalline patch bound to an adhesive and deformable sphere, where the distinct patterns of relaxation become, respectively, radial chains of dislocations, or ``scars'', and radial wrinkles. Analysis of highly-wrinkled and defect-riddle states reveals remarkably that both modes achieve the identical mechanical state in the limits of vanishing thickness and lattice spacing, and further, that the degeneracy between these modes is lifted only by the microscopic and sub-dominant energetics that select their optimal symmetry. We present a structural relaxation phase diagram that predicts a wrinkle-to-scar transition driven both by increasing substrate stiffness and substrate curvature.

  8. Effects of surface properties on the impact process of a yield stress fluid drop

    Energy Technology Data Exchange (ETDEWEB)

    Saidi, Alireza [UMR 5518 CNRS-Grenoble Institut Polytechnique (Grenoble INP), Laboratory of Pulp and Paper Science and Graphic Arts (LGP2), St Martin d' Heres (France); Martin, Celine [UMR 5518 CNRS-Grenoble Institut Polytechnique (Grenoble INP), Laboratory of Pulp and Paper Science and Graphic Arts (LGP2), St Martin d' Heres (France); Universite Joseph Fourier Grenoble I, CNRS, Laboratoire de Rheologie, CNRS UMR 5520, Grenoble Institut Polytechnique, BP 53, Grenoble Cedex 9 (France); Magnin, Albert [Universite Joseph Fourier Grenoble I, CNRS, Laboratoire de Rheologie, CNRS UMR 5520, Grenoble Institut Polytechnique, BP 53, Grenoble Cedex 9 (France)

    2011-07-15

    The impact of a yield stress fluid drop onto a solid surface with diversified interface properties has been experimentally investigated. Two smooth substrates with distinct surface energies and three similar substrates with different roughnesses have been used. The bulk shear rheological behaviour of Carbopol gels, concentrated suspensions of swollen micro-gels, has been measured. Wall friction has also been characterized on each substrate. Slip effects of gels proved to be greater on a more hydrophobic substrate. They decreased with an increase in roughness. The drop hydrodynamics during the impact was correlated with the wall friction of the gels on all substrates and with the ratio of surface roughness to size of the swollen micro-gels. At very low impact velocities, the gravitational subsidence amplitude depends greatly on surface properties. At higher impact velocities, no significant difference is observed during the spreading phase. The drop behaviour differs during the retraction depending on the substrate. Interface effects during the retraction stage proved to diminish when the yield stress value increases. (orig.)

  9. Experimental Research on Residual Stress in Surface of Silicon Nitride Ceramic Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The influence of the residual stress in surface of ceramic balls on the fatigue life is large, because the life of silicon nitride ball bearings is more sensitive to the load acted on the bearings than the life of all-steel ball bearings. In this paper, the influence of thermal stress produced in sintering and mechanical stress formed in lapping process on residual stress in surface of silicon nitride ceramic balls was discussed. The residual compress stress will be formed in the surface of silicon nitride ...

  10. Reference Values of Oxidative Stress Parameters in Adult Iranian Fat-Tailed Sheep

    Directory of Open Access Journals (Sweden)

    S. Nazifi*, N. Ghafari1, F. Farshneshani, M. Rahsepar and S. M. Razavi1

    2010-01-01

    Full Text Available The present study was performed on 111 adult clinically healthy Iranian fat-tailed sheep from both sexes (28 male and 83 female. Blood concentrations of oxidative stress parameters viz. malondialdehyde (MDA, superoxide dismutase (SOD, catalase (CAT and glutathione peroxidase (GPX were determined. The reference values for oxidative stress parameters of adult clinically healthy Iranian fat-tailed sheep were as followed: MDA 0.53-0.60 mmol/l, SOD 948.65-1011.50 U/gHb, CAT 1834.29-1915.63 U/gHb and GPX 191.67-196.52 U/gHb. There were no significant differences in oxidative stress parameters among animal of the two sexes.

  11. Refraction of the principal stress trajectories and the stress jumps on faults and contact surfaces: Part 1. Non-constrained regular trajectories

    Science.gov (United States)

    Mukhamediev, Sh. A.

    2014-09-01

    Rock masses contain ubiquitous multiscale heterogeneities, which (or whose boundaries) serve as the surfaces of discontinuity for some characteristics of the stress state, e.g., for the orientation of principal stress axes. Revealing the regularities that control these discontinuities is a key to understanding the processes taking place at the boundaries of the heterogeneities and for designing the correct procedures for reconstructing and theoretical modeling of tectonic stresses. In the present study, the local laws describing the refraction of the axes of extreme principal stresses T 1 (maximal tension in the deviatoric sense) and T 3 (maximal compression) of the Cauchy stress tensor at the transition over the elementary area n of discontinuity whose orientation is specified by the unit normal n are derived. It is assumed that on the area n of discontinuity, frictional contact takes place. No hypotheses are made on the constitutive equations, and a priori constraints are not posed on the orientation on the stress axes. Two domains, which adjoin area n on the opposite sides and are conventionally marked + and -, are distinguished. In the case of the two-dimensional (2D) stress state, any principal stress axis on passing from domain - to domain + remains in the same quadrant of the plane as the continuation of this axis in domain +. The sign and size of the refraction angle depend on the sign and amplitude of the jump of the normal stress, which is tangential to the surface of discontinuity. In the three-dimensional (3D) case, the refraction of axes T 1 and T 3 should be analyzed simultaneously. For each side, + and -, the projections of the T 1 and T 3 axes on the generally oriented plane n form the shear sectors S + and S -, which are determined unambiguously and to whose angular domains the possible directions p + and p - of the shear stress vectors belong. In order for the extreme stress axes T {1/+}, T {3/+} and T {1/-}, T {3/-} to be statically compatible on

  12. Prognostic value of non-invasive stress testing for coronary artery disease in obese patients.

    Science.gov (United States)

    Bigvava, Tamar; Zamani, Seyedeh Mahsa; Pieske-Kraigher, Elisabeth; Gebker, Rolf; Pieske, Burkert; Kelle, Sebastian

    2015-12-01

    Detecting coronary artery disease (CAD) in obese patients remains a challenge but can have substantial prognostic implications for this patient group. Until now, sufficient data was not available on which to base the selection of the imaging modality in obese patients. The decision on which imaging modality to use should therefore follow the general guidelines. In this article, the authors discuss the prognostic value of the different non-invasive stress testing methods for CAD in obese patients.

  13. Review of family relational stress and pediatric asthma: the value of biopsychosocial systemic models.

    Science.gov (United States)

    Wood, Beatrice L; Miller, Bruce D; Lehman, Heather K

    2015-06-01

    Asthma is the most common chronic disease in children. Despite dramatic advances in pharmacological treatments, asthma remains a leading public health problem, especially in socially disadvantaged minority populations. Some experts believe that this health gap is due to the failure to address the impact of stress on the disease. Asthma is a complex disease that is influenced by multilevel factors, but the nature of these factors and their interrelations are not well understood. This paper aims to integrate social, psychological, and biological literatures on relations between family/parental stress and pediatric asthma, and to illustrate the utility of multilevel systemic models for guiding treatment and stimulating future research. We used electronic database searches and conducted an integrated analysis of selected epidemiological, longitudinal, and empirical studies. Evidence is substantial for the effects of family/parental stress on asthma mediated by both disease management and psychobiological stress pathways. However, integrative models containing specific pathways are scarce. We present two multilevel models, with supporting data, as potential prototypes for other such models. We conclude that these multilevel systems models may be of substantial heuristic value in organizing investigations of, and clinical approaches to, the complex social-biological aspects of family stress in pediatric asthma. However, additional systemic models are needed, and the models presented herein could serve as prototypes for model development.

  14. Not all resources are created equal: COR theory, values, and stress.

    Science.gov (United States)

    Morelli, Neil A; Cunningham, Christopher J L

    2012-01-01

    The common usage of conservation of resources (COR) theory highlights the quantity of resources in explaining stress reactions and responses. To expand the theoretical understanding and explanatory power of COR theory, this study tested the proposition that the perceived importance of an individual's resources is a function of personal values. Using a value framework based on Schwartz (1994), it was expected that values would influence both the appraisal of resource importance and coping behaviors. Results from both student and working samples indicated that while resource importance did not clearly mediate all of the coping outcomes, values did have an influence on the importance an individual assigns to resources. Measurement and theoretical implications related to COR theory are discussed.

  15. 生物刺激反馈治疗女性压力性尿失禁:可提高轻、中度压力性尿失禁时盆底肌肉收缩表面肌电值%Biostimulation feedback treatment improves surface electromyography value of pelvic floor muscle during contraction in women with mild and moderate stress urinary incontinence

    Institute of Scientific and Technical Information of China (English)

    冯玲

    2014-01-01

    BACKGROUND:Biostimulation feedback treatment has been widely used for female stress urinary incontinence. The treatment principle is based on the electromyographic signal measured and the combination of biofeedback technique and electrotherapy technique. OBJECTIVE:To evaluate the effect of biofeedback electrical stimulation in treatment of female stress urinary incontinence. METHODS:Thirty female patients suffering from light or moderate stress urinary incontinence received biofeedback electrical stimulation for 4-8 weeks. The stimulation parameters were 60 Hz, 20-60 mA, 12-second feedback. The patients were instructed to contract pelvic floor muscle. The peak value of surface electromyography in pelvic floor muscular 2-second-rapid-contraction, mean value of pelvic floor muscular 10-second-contraction, mean value of the pelvic floor muscular 60-second-tolerance-contraction, and the rate of urine leakage were observed before and after treatment. RESULTS AND CONCLUSION:The peak value of surface electromyography in pelvic floor muscular 2-second-rapid-contraction, mean value of pelvic floor muscular 10-second-contraction, and mean value of the pelvic floor muscular 60-second-tolerance-contraction were significantly increased after treatment, compared with before treatment (P  目的:探讨盆底生物刺激反馈治疗对女性压力性尿失禁的治疗效果。  方法:采用盆底生物刺激反馈治疗仪治疗30例轻、中度压力性尿失禁女性患者,治疗时间4-8周,设置刺激参数60 Hz、20-60 mA,反馈12 s指导患者收缩盆底肌肉,分析治疗前后患者盆底肌肉2 s快速收缩表面肌电最大值、盆底肌肉持续10 s收缩表面肌电平均值、盆底肌肉60 s耐受收缩表面肌电平均值变化,并观察每天漏尿次数。  结果与结论:患者治疗后盆底肌肉2 s快速收缩表面肌电最大值、盆底肌肉持续10 s收缩表面肌电平均值、盆底肌肉60 s耐受收缩表面肌电

  16. ACHIEVING THRESHOLD BARRIER OF 1 nm ROUGHNESS VALUE OF SILICON SURFACE BY DIAMOND TURNING

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    1 nm roughness value of silicon surface by diamond turning is obtained firstly and three novel techniques are proposed. The surface integrity is studied in detail by using atomic force microscope, scanning electron microscope, and stylus surface instrument. The diamond tool sharpness hasa considerable influence on the machined surface, therefore a novel technique-brightness modulation for measuring accurately the edge of the cutter is proposed. Mirror surfaces are assessed by another novel technique-a measure of their reflectivity. A third technique, single grit diamond machining is carried out. It supplies a experimental evidence for verifying the obtained high quality turned surfaces.

  17. Technical paper: Environmental heat stress in football is increased in synthetic surfaces

    OpenAIRE

    Luis Fernando Aragón Vargas

    2012-01-01

    Environmental heat stress is the result of ambient temperature, radiation, and relative humidity. During football practice on synthetic surfaces and no roof, solar radiation causes an important temperature increase of the playing surface. This technical note explains how heat stress is calculated according to the WBGT index (which does not consider playing surface temperature), and quantifies the increase in a synthetic surface compared to natural grass on the same site. Football practice sho...

  18. Surface Finish and Residual Stresses Induced by Orthogonal Dry Machining of AA7075-T651.

    Science.gov (United States)

    Jomaa, Walid; Songmene, Victor; Bocher, Philippe

    2014-02-28

    The surface finish was extensively studied in usual machining processes (turning, milling, and drilling). For these processes, the surface finish is strongly influenced by the cutting feed and the tool nose radius. However, a basic understanding of tool/surface finish interaction and residual stress generation has been lacking. This paper aims to investigate the surface finish and residual stresses under the orthogonal cutting since it can provide this information by avoiding the effect of the tool nose radius. The orthogonal machining of AA7075-T651 alloy through a series of cutting experiments was performed under dry conditions. Surface finish was studied using height and amplitude distribution roughness parameters. SEM and EDS were used to analyze surface damage and built-up edge (BUE) formation. An analysis of the surface topography showed that the surface roughness was sensitive to changes in cutting parameters. It was found that the formation of BUE and the interaction between the tool edge and the iron-rich intermetallic particles play a determinant role in controlling the surface finish during dry orthogonal machining of the AA7075-T651 alloy. Hoop stress was predominantly compressive on the surface and tended to be tensile with increased cutting speed. The reverse occurred for the surface axial stress. The smaller the cutting feed, the greater is the effect of cutting speed on both axial and hoop stresses. By controlling the cutting speed and feed, it is possible to generate a benchmark residual stress state and good surface finish using dry machining.

  19. Temperature change and stress distribution analysis of die surface in Al-alloy die casting process and experimental study on die heat check

    Institute of Scientific and Technical Information of China (English)

    Hu Xinping; Zhao Guoqun; Wu Bingyao

    2008-01-01

    The temperature change of the die surface in practical aluminum alloy die casting process was analyzed,and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze the stress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steel in different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress (maximum 1.5 GPa) caused in the die filling and die spraying stages was larger than the mechanical stress (maximum 85 MPa)caused in the die locking stage. The results of the thermal check experiment showed that there were three stages of die dissolving, and that the stress distribution shown by the samples' cracking routine was close to the die surface stress analysis.

  20. Turbulent oscillating channel flow subjected to a free-surface stress.

    NARCIS (Netherlands)

    Kramer, W.; Clercx, H.J.H.; Armenio, V.

    2010-01-01

    The channel flow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean flow develops. The Reynolds number is

  1. Profiling nurses' job satisfaction, acculturation, work environment, stress, cultural values and coping abilities: A cluster analysis.

    Science.gov (United States)

    Goh, Yong-Shian; Lee, Alice; Chan, Sally Wai-Chi; Chan, Moon Fai

    2015-08-01

    This study aimed to determine whether definable profiles existed in a cohort of nursing staff with regard to demographic characteristics, job satisfaction, acculturation, work environment, stress, cultural values and coping abilities. A survey was conducted in one hospital in Singapore from June to July 2012, and 814 full-time staff nurses completed a self-report questionnaire (89% response rate). Demographic characteristics, job satisfaction, acculturation, work environment, perceived stress, cultural values, ways of coping and intention to leave current workplace were assessed as outcomes. The two-step cluster analysis revealed three clusters. Nurses in cluster 1 (n = 222) had lower acculturation scores than nurses in cluster 3. Cluster 2 (n = 362) was a group of younger nurses who reported higher intention to leave (22.4%), stress level and job dissatisfaction than the other two clusters. Nurses in cluster 3 (n = 230) were mostly Singaporean and reported the lowest intention to leave (13.0%). Resources should be allocated to specifically address the needs of younger nurses and hopefully retain them in the profession. Management should focus their retention strategies on junior nurses and provide a work environment that helps to strengthen their intention to remain in nursing by increasing their job satisfaction.

  2. Finite Element Analysis and Experiment Research on Surface Residual Stress of Ceramics Grinding

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the distributing regulation of residual stress can be simplified into thermal elastioplastic mechanical issue, under the action of the both moving centralized force and heat source. Calculating and evaluating of surface residual stress using current procedure of finite element analysis which has been...

  3. Retrieval of ocean surface wind stress and drag coefficient from spaceborne SAR

    Institute of Scientific and Technical Information of China (English)

    杨劲松; 黄韦艮; 周长宝

    2001-01-01

    A model for retrieval of wind stress and drag coefficient on the sea surface with the data measured by spacebome synthetic aperture radar (SAR) has been developed based on the SAR imaging mechanisms of ocean surface capillary waves and short gravity waves. This model consists of radiometric calibration, wind speed retrieval and wind stress and drag coefficient calculation. A Radarsat SAR image has been used to calculate wind stress and drag coeffi cient. Good results have been achieved.

  4. Stress Formation During Self-Assembly of Alkanethiols on Differently Pre-Treated Gold Surfaces

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Mortensen, Michael Wrang; Andersen, Jens Enevold Thaulov

    2001-01-01

    surface roughness induced by aqua regia etching, resulting in a higher density of adsorption sites. Surfaces cleaned willi oxygen plasma, however, give more reproducible stress change curves. The stress change curves of surfaces cleaned with aqua regia become less stable af ter three subsequent cleanings...... the rate and reproducibility of the adsorption process. Further objectives have been to maximise the stress signal during adsorption and to develop a method for removing sulphur immobilised molecules. Before each adsorption experiment the gold surface was cleaned in aqua regia, or in oxygen plasma....... Adsorption of alkanethiols caused changes in surface stress, which closely followed Langmuir type kinetics. Cleaning with aqua regia generally provides higher adsorption rates and a larger stress change than cleaning with oxygen plasma. Based on AFM imaging, we propose that this is related to a larger...

  5. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  6. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  7. Numerical analysis of residual stress of Al-Mg-Mn-Sc-Zr alloy subjected to surface strengthening by shot peening

    Directory of Open Access Journals (Sweden)

    Mariusz Stegliński

    2015-03-01

    Full Text Available In this paper, we presented the results of the analysis of the stresses in the Al-Mg5%-Mn1,5%-Sc0,8%-Zr0,4% alloy after shot peening process using solver ANSYSANSYSANSYS LS-Dyna. The computational model illustrates the phenomena occurring as a result of plastic deformation caused by hitting a steel ball on the surface of the analyzed aluminium alloy. We analyzed two input variables: diameter and speed of a ball. The resulting normal stress distribution centred exposes the minimum compressive stress at a position located at a depth point of Belayev 0.125 mm with a value of σ = –345 MPa. Variable parameter shows the correlation of the boundary conditions of minimum stress increase with increasing ball’s diameter and its speed. Selected points of numerical analysis were verified with experimental results.[b]Keywords[/b]: materials science, numerical analysis, metal forming, shot peening, aluminium

  8. Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

    Directory of Open Access Journals (Sweden)

    Rousse Maria G

    2011-04-01

    Full Text Available Abstract Background The determination of coronary flow reserve (CFR is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD coronary artery. Methods A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography. Results The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%. Mean CFR was 2.67 at de end of dobutamine test. There was an excellent concordance between delta HR (difference between baseline HR and maximum HR and the increase in the CFR (correlation coefficient 0.84. In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%. In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99% at 75% of their predicted maximum heart rate. Conclusions We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm

  9. Interval Estimation of Stress-Strength Reliability Based on Lower Record Values from Inverse Rayleigh Distribution

    Directory of Open Access Journals (Sweden)

    Bahman Tarvirdizade

    2014-01-01

    Full Text Available We consider the estimation of stress-strength reliability based on lower record values when X and Y are independently but not identically inverse Rayleigh distributed random variables. The maximum likelihood, Bayes, and empirical Bayes estimators of R are obtained and their properties are studied. Confidence intervals, exact and approximate, as well as the Bayesian credible sets for R are obtained. A real example is presented in order to illustrate the inferences discussed in the previous sections. A simulation study is conducted to investigate and compare the performance of the intervals presented in this paper and some bootstrap intervals.

  10. Comparison of local stress values obtained by two measuring methods on blast furnace shell

    Directory of Open Access Journals (Sweden)

    P. Bigoš

    2015-01-01

    Full Text Available This paper describes measuring of time behaviour specified for local stress increments on the blast furnace shell that were performed using strain gauge sensors. These results are compared with values obtained by means of the second specific measuring method. There is also presented in this paper a commentary and discussion concerning the measured time behaviour obtained from the both measuring methods. This article presents results from another of experimental analysis series concerning the blast furnace shell in one concrete metallurgical plant.

  11. Effect of surface stress states on the corrosion behavior of alloy 690

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Mo; Shim, Hee Sang; Seo, Myung Ji; Hur, Do Haeng [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The test environment simulated the primary water chemistry in PWRs. Dissolved oxygen (DO), dissolved hydrogen (DH), pH and conductivity were monitored at room temperature using sensors manufactured by Orbisphere and Mettler Toledo. The temperature and pressure were maintained at 330 .deg. C and 150 bars during the corrosion test. The condition of the test solution was lithium (LiOH) 2 ppm and boron (H3BO4) 1,200 ppm, DH 35 cc/kg (STP) and less than 5 ppb DO. The flow rate of the loop system was 3.8 L/hour. Corrosion tests were conducted for 500 hours. The corrosion release rate was evaluated by a gravimetric analysis method using a two-step alkaline permanganate-ammonium citrate (AP/AC) descaling process. Compressive residual stress is induced by shot peening treatment but its value reveals some different trend between the shot peening intensity on the surface of Alloy 690 TT. A higher shot peening intensity causes a reduction in the corrosion rate and it is considered that the compressive residual stress beneath the surface layer suppresses the metal ion transfer in an alloy matrix.

  12. An analytical and numerical study of the nonlinear reflection at a stress-free surface

    Science.gov (United States)

    Romer, Anne; Kim, Jin-Yeon; Jacobs, Laurence J.

    2015-03-01

    Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic waves generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on a perturbation method. Here, the model is chosen to mimic an experimental setup where the longitudinal wave is generated at oblique angle using a wedge transducer. Due to the mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stress-free boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid interaction with diffracted waves.

  13. An analytical and numerical study of the nonlinear reflection at a stress-free surface

    Energy Technology Data Exchange (ETDEWEB)

    Romer, Anne, E-mail: anne.romer@gmx.net; Kim, Jin-Yeon, E-mail: anne.romer@gmx.net [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Jacobs, Laurence J. [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA and G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2015-03-31

    Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic waves generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on a perturbation method. Here, the model is chosen to mimic an experimental setup where the longitudinal wave is generated at oblique angle using a wedge transducer. Due to the mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stress-free boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid interaction with diffracted waves.

  14. Surface stress relaxation of oxide glasses: The effects on mechanical strength

    Science.gov (United States)

    Lezzi, Peter Joseph

    A new glass strengthening mechanism based upon surface compressive stress formation by surface stress relaxation of glasses that were held under a tensile stress, at a temperature lower than the glass transition temperature, in low water vapor pressure, has been demonstrated. Although glass fibers are traditionally known to become mechanically weaker when heat-treated at a temperature lower than the glass transition temperature in the presence of water vapor, the strength was found to become greater than the as-received fiber strength when fibers were subjected to a sub-critical tensile stress during heat-treatment. The observed strengthening was attributed to surface compressive residual stress formation through surface stress relaxation during the sub-critical tensile stress application in the atmosphere containing water vapor. Surface stress relaxation of the same glass fibers was shown to take place under conditions identical to those experienced by the strengthened mechanical test specimens by observing permanent bending of the fiber. Furthermore, the magnitude and presence of the residual stresses formed during bending or tensile heat-treatments were confirmed by FTIR, fiber etching, and fiber slicing methods. The method can in principle be used to strengthen any oxide glass and is not subjected to the constraints of traditional strengthening methods such as a minimum thickness for tempering, or a glass containing alkali ions for ion-exchange. Thus far, the method has been successful in strengthening silica glass, E-glass, and soda-lime silicate glass by approximately 20-30%.

  15. Impact of Surface Chemistry on Grain Boundary Induced Intrinsic Stress Evolution during Polycrystalline Thin Film Growth

    Science.gov (United States)

    Qi, Y.; Sheldon, B. W.; Guo, H.; Xiao, X.; Kothari, A. K.

    2009-02-01

    First principles calculations were integrated with cohesive zone and growth chemistry models to demonstrate that adsorbed species can significantly alter stresses associated with grain boundary formation during polycrystalline film growth. Using diamond growth as an example, the results show that lower substrate temperatures increase the hydrogen content at the surface, which reduces tensile stress, widens the grain boundary separations, and permits additional atom insertions that can induce compressive stress. More generally, this work demonstrates that surface heteroatoms can lead to behavior which is not readily described by existing models of intrinsic stress evolution.

  16. Technical paper: Environmental heat stress in football is increased in synthetic surfaces

    Directory of Open Access Journals (Sweden)

    Luis Fernando Aragón Vargas

    2012-06-01

    Full Text Available Environmental heat stress is the result of ambient temperature, radiation, and relative humidity. During football practice on synthetic surfaces and no roof, solar radiation causes an important temperature increase of the playing surface. This technical note explains how heat stress is calculated according to the WBGT index (which does not consider playing surface temperature, and quantifies the increase in a synthetic surface compared to natural grass on the same site. Football practice should be avoided during those hours with the highest solar radiation and temperature on this type of surface.

  17. Variation in wind speed and surface shear stress from open floor to porous parallel windbreaks: A wind tunnel study

    Science.gov (United States)

    Guan, De-Xin; Zhong, Ye; Jin, Chang-Jie; Wang, An-Zhi; Wu, Jia-Bing; Shi, Ting-Ting; Zhu, Ting-Yao

    2009-08-01

    As vegetative windbreaks become established on a large scale in agricultural ecosystems, understanding the influence of windbreak networks on the momentum budget of the atmospheric boundary layer becomes important. The authors conducted a wind tunnel experiment to study the variation of wind speed profile and surface shear stress of wind flow passing from an open surface to another with parallel windbreaks. Five spacing (L = 5, 10, 15, 20, 30 h, wherein h is the windbreak height) windbreak arrays with moderate porosity (aerodynamic porosity α = 0.501) were used in the experiments. Both near-floor and over-array wind speed measurements showed that airflow will approach equilibrium state behind a special windbreak of the array, varying from 4th to 9th windbreak when the spacing change from 30 to 5 h. Within the range of L/h values investigated, arrays with narrower spacing cause higher friction velocity and roughness length, which were up to 2.26 and nearly 100 times those observed over open floor, respectively. A semiempirical momentum budget model is developed on the arrayed surface to estimate windbreak drag and shear stress on the protected floor. Windbreak drag accounts for more than 80% of shear stress on the arrayed surface, and the shear stress on protected floor is less than 20% when L/h < 40 based on the model estimation. The sum of the two estimated components agrees well with the estimates obtained from over-array wind profiles.

  18. Prognostic value of adenosine stress cardiovascular magnetic resonance in patients with low-risk chest pain

    Directory of Open Access Journals (Sweden)

    Oshinski John N

    2009-09-01

    Full Text Available Abstract Background Approximately 5% of patients with an acute coronary syndrome are discharged from the emergency room with an erroneous diagnosis of non-cardiac chest pain. Highly accurate non-invasive stress imaging is valuable for assessment of low-risk chest pain patients to prevent these errors. Adenosine stress cardiovascular magnetic resonance (AS-CMR is an imaging modality with increasing application. The goal of this study was to evaluate the negative prognostic value of AS-CMR among low-risk acute chest pain patients. Methods We studied 103 patients, mean 56.7 ± 12.3 years of age, with chest pain and no electrocardiographic evidence of ischemia and negative cardiac biomarkers of necrosis, who were admitted to the Cardiac Decision Unit of our institution. All patients underwent AS-CMR. A negative AS-CMR was defined as absence of all the following: regional wall motion abnormalities at rest; perfusion defects during stress (adenosine and rest; and myocardial scar on late gadolinium enhancement images. The patients were followed for a mean of 277 (range 161-462 days. The primary end point was defined as the combination of cardiac death, nonfatal acute myocardial infarction, re-hospitalization for chest pain, obstructive coronary artery disease (>50% coronary stenosis on invasive angiography and coronary revascularization. Results In 14 patients (13.6%, AS-CMR was positive. The remaining 89 patients (86.4%, who had negative AS-CMR, were discharged. No patient with negative AS-CMR reached the primary end-point during follow-up. The negative predictive value of AS-CMR was 100%. Conclusion AS-CMR holds promise as a useful tool to rule out significant coronary artery disease in patients with low-risk chest pain. Patients with negative AS-CMR have an excellent short and mid-term prognosis.

  19. Manipulating environmental stresses and stress tolerance of microalgae for enhanced production of lipids and value-added products-A review.

    Science.gov (United States)

    Chen, Bailing; Wan, Chun; Mehmood, Muhammad Aamer; Chang, Jo-Shu; Bai, Fengwu; Zhao, Xinqing

    2017-05-31

    Microalgae have promising potential to produce lipids and a variety of high-value chemicals. Suitable stress conditions such as nitrogen starvation and high salinity could stimulate synthesis and accumulation of lipids and high-value products by microalgae, therefore, various stress-modification strategies were developed to manipulate and optimize cultivation processes to enhance bioproduction efficiency. On the other hand, advancements in omics-based technologies have boosted the research to globally understand microalgal gene regulation under stress conditions, which enable further improvement of production efficiency via genetic engineering. Moreover, integration of multi-omics data, synthetic biology design, and genetic engineering manipulations exhibits a tremendous potential in the betterment of microalgal biorefinery. This review discusses the process manipulation strategies and omics studies on understanding the regulation of metabolite biosynthesis under various stressful conditions, and proposes genetic engineering of microalgae to improve bioproduction via manipulating stress tolerance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Geometrical Considerations for Piezoresistive Microcantilever Response to Surface Stress during Chemical Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Loui, A; Goericke, F; Ratto, T; Lee, J; Hart, B; King, W

    2008-04-25

    We have designed, fabricated, and tested five piezoresistive cantilever configurations to investigate the effect of shape and piezoresistor placement on the sensitivity of microcantilevers under either point loading and surface stress loading. The experimental study reveals that: (1) high aspect ratio cantilevers that are much longer than they are wide are optimal for point-loading applications such as microscopy and force measurements; (2) low aspect ratio cantilevers that are short and wide are optimal for surface stress loading scenarios such as those that occur in biological and chemical sensor applications. The sensitivity data for both point loads and surface stress are consistent with previously developed finite-element models.

  1. A stress tensor eigenvector projection space for the (H2O)5 potential energy surface

    Science.gov (United States)

    Xu, Tianlv; Farrell, James; Momen, Roya; Azizi, Alireza; Kirk, Steven R.; Jenkins, Samantha; Wales, David J.

    2017-01-01

    A stress tensor eigenvector projection space is created to describe reaction pathways on the (H2O)5 MP2 potential energy surface. Evidence for the stabilizing role of the O--O bonding interactions is found from the length of the recently introduced stress tensor trajectory in the stress tensor eigenvector projection space. The stress tensor trajectories demonstrate coupling behavior of the adjoining covalent (σ) O-H and hydrogen bonds due to sharing of covalent character. Additionally, the stress tensor trajectories can show dynamic coupling effects of pairs of σ bonds and of pairs of hydrogen bonds.

  2. Experimental measurements of surface damage and residual stresses in micro-engineered plasma facing materials

    Science.gov (United States)

    Rivera, David; Wirz, Richard E.; Ghoniem, Nasr M.

    2017-04-01

    The thermomechanical damage and residual stresses in plasma-facing materials operating at high heat flux are experimentally investigated. Materials with micro-surfaces are found to be more resilient, when exposed to cyclic high heat flux generated by an arc-jet plasma. An experimental facility, dedicated to High Energy Flux Testing (HEFTY), is developed for testing cyclic heat flux in excess of 10 MW/m2. We show that plastic deformation and subsequent fracture of the surface can be controlled by sample cooling. We demonstrate that W surfaces with micro-pillar type surface architecture have significantly reduced residual thermal stresses after plasma exposure, as compared to those with flat surfaces. X-ray diffraction (XRD) spectra of the W-(110) peak reveal that broadening of the Full Width at Half Maximum (FWHM) for micro-engineered samples is substantially smaller than corresponding flat surfaces. Spectral shifts of XRD signals indicate that residual stresses due to plasma exposure of micro-engineered surfaces build up in the first few cycles of exposure. Subsequent cyclic plasma heat loading is shown to anneal out most of the built-up residual stresses in micro-engineered surfaces. These findings are consistent with relaxation of residual thermal stresses in surfaces with micro-engineered features. The initial residual stress state of highly polished flat W samples is compressive (≈ -1.3 GPa). After exposure to 50 plasma cycles, the surface stress relaxes to -1.0 GPa. Micro-engineered samples exposed to the same thermal cycling show that the initial residual stress state is compressive at (- 250 MPa), and remains largely unchanged after plasma exposure.

  3. The Alignment of the Mean Wind and Stress Vectors in the Unstable Surface Layer

    Science.gov (United States)

    Bernardes, M.; Dias, N. L.

    2010-01-01

    A significant non-alignment between the mean horizontal wind vector and the stress vector was observed for turbulence measurements both above the water surface of a large lake, and over a land surface (soybean crop). Possible causes for this discrepancy such as flow distortion, averaging times and the procedure used for extracting the turbulent fluctuations (low-pass filtering and filter widths etc.), were dismissed after a detailed analysis. Minimum averaging times always less than 30 min were established by calculating ogives, and error bounds for the turbulent stresses were derived with three different approaches, based on integral time scales (first-crossing and lag-window estimates) and on a bootstrap technique. It was found that the mean absolute value of the angle between the mean wind and stress vectors is highly related to atmospheric stability, with the non-alignment increasing distinctively with increasing instability. Given a coordinate rotation that aligns the mean wind with the x direction, this behaviour can be explained by the growth of the relative error of the u- w component with instability. As a result, under more unstable conditions the u- w and the v- w components become of the same order of magnitude, and the local stress vector gives the impression of being non-aligned with the mean wind vector. The relative error of the v- w component is large enough to make it undistinguishable from zero throughout the range of stabilities. Therefore, the standard assumptions of Monin-Obukhov similarity theory hold: it is fair to assume that the v- w stress component is actually zero, and that the non-alignment is a purely statistical effect. An analysis of the dimensionless budgets of the u- w and the v- w components confirms this interpretation, with both shear and buoyant production of u- w decreasing with increasing instability. In the v- w budget, shear production is zero by definition, while buoyancy displays very low-intensity fluctuations around

  4. Method for estimating `K` value for a case where concentrated load acts upon a crack surface; Kiretsumen ni shuchu kaju ga sayosuru baai no K chi suiteiho ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Toyosada, M.; Goto, K.; Niwa, T.; Maki, M. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1996-10-01

    A proposal was made on a method to estimate simply the `K` value where concentrated load acts upon a crack surface by utilizing results of stress analysis for the crack-free problem against one external load, and `K` value analysis against different crack lengths. If a `K` value is known when concentrated load acts upon a crack surface, `K` values due to each external load and remaining stress can be estimated. This is possible by using the superposition principle with which stress distribution and remaining stress distribution for the crack-free problem are given on a case where each external load acts upon, and the `K` value for the case when concentrated load acts upon a crack surface is integrated by considering the above distributions. For the case where concentrated load acts upon a crack surface of CT test pieces, the crack length and the position on which the concentrated load acts upon are varied, and the `K` value for the case where concentrated load acts upon a crack surface is derived by BEM, whereas the derived `K` value-related expression was expressed by a polynomial approximation. From these results, it was found that the `K` value can be estimated easily for the case where the concentrated load acts upon a crack surface at accuracy presenting no problems in practical use. 5 refs., 8 figs.

  5. Introduction of Enhanced Compressive Residual Stress Profiles in Aerospace Components Using Combined Mechanical Surface Treatments

    Science.gov (United States)

    Gopinath, Abhay; Lim, Andre; Nagarajan, Balasubramanian; Cher Wong, Chow; Maiti, Rajarshi; Castagne, Sylvie

    2016-11-01

    Mechanical surface treatments such as Shot Peening (SP) and Deep Cold Rolling (DCR) are being used to introduce Compressive Residual Stress (CRS) at the surface and subsurface layers of aerospace components, respectively. This paper investigates the feasibility of a combined introduction of both the surface and sub-surface compressive residual stress on Ti6Al4V material through a successive application of the two aforementioned processes, one after the other. CRS profiles between individual processes were compared to that of combination of processes to validate the feasibility. It was found out that shot peening introduces surface compressive residual stress into the already deep cold rolled sample, resulting in both surface and sub-surface compressive residual stresses in the material. However the drawback of such a combination would be the increased surface roughness after shot peening a deep cold rolled sample which can be critical especially in compressor components. Hence, a new technology, Vibro-Peening (VP) may be used as an alternative to SP to introduce surface stress at reduced roughness.

  6. Surface patterns on single-crystal films under uniaxial stress: Experimental evidence for the Grinfeld instability

    Science.gov (United States)

    Berréhar, J.; Caroli, C.; Lapersonne-Meyer, C.; Schott, M.

    1992-11-01

    We study the stress relaxation in single-crystal films of polymerized polydiacetylene, in epitaxy with their monomer substrate. Polymerization induces a uniaxial stress. Two types of surface patterns are observed and studied by atomic force microscopy: films thicker than 175 nm exhibit quasiperiodic cracks perpendicular to the polymer chains; thinner ones exhibit regular wrinkles with the same orientation. The wrinkle surface deformation is stress relaxing and plastic. We show that all experimental results, in particular, the order of magnitude of the pattern spacings, are compatible with the following interpretation: as polymerization proceeds, the uniaxial stress generates a Grinfeld instability (Dok. Akad. Nauk SSSR 290, 1358 (1986) [Sov. Phys. Dokl. 31, 831 (1986)]) fed by surface diffusion. The crack pattern is a secondary instability, initiated at the sites of stress concentration provided by the wrinkles.

  7. Stress errors in a case of developmental surface dyslexia in Filipino.

    Science.gov (United States)

    Dulay, Katrina May; Hanley, J Richard

    2015-01-01

    This paper reports the case of a dyslexic boy (L.A.) whose impaired reading of Filipino is consistent with developmental surface dyslexia. Filipino has a transparent alphabetic orthography with stress typically falling on the penultimate syllable of multisyllabic words. However, exceptions to the typical stress pattern are not marked in the Filipino orthography. L.A. read words with typical stress patterns as accurately as controls, but made many more stress errors than controls when reading Filipino words with atypical stress. He regularized the pronunciation of many of these words by incorrectly placing the stress on the penultimate syllable. Since he also read nonwords as accurately and quickly as controls and performed well on tests of phonological awareness, L.A. appears to present a clear case of developmental surface dyslexia in a transparent orthography.

  8. Self-perception and value system as possible predictors of stress.

    Science.gov (United States)

    Sivberg, B

    1998-03-01

    This study was directed towards personality-related, value system and sociodemographic variables of nursing students in a situation of change, using a longitudinal perspective to measure their improvement in principle-based moral judgement (Kohlberg; Rest) as possible predictors of stress. Three subgroups of students were included from the commencement of the first three-year academic nursing programme in 1993. The students came from the colleges of health at Jönköping, Växjö and Kristianstad in the south of Sweden. A principal component factor analysis (varimax) was performed using data obtained from the students in the spring of 1994 (n = 122) and in the spring of 1996 (n = 112). There were 23 variables, of which two were sociodemographic, eight represented self-image, six were self-values, six were interpersonal values, and one was principle-based moral judgement. The analysis of data from students in the first year of a three-year programme demonstrated eight factors that explained 68.8% of the variance. The most important factors were: (1) ascendant decisive disorderly sociability and nonpractical mindedness (18.1% of the variance); (2) original vigour person-related trust (13.3%) of the variance); (3) orderly nonvigour achievement (8.9% of the variance) and (4) independent leadership (7.9% of the variance). (The term 'ascendancy' refers to self-confidence, and 'vigour' denotes responding well to challenges and coping with stress.) The analysis in 1996 demonstrated nine factors, of which the most important were: (1) ascendant original sociability with decisive nonconformist leadership (18.2% of the variance); (2) cautious person-related responsibility (12.6% of the variance); (3) orderly nonvariety achievement (8.4% of the variance); and (4) nonsupportive benevolent conformity (7.2% of the variance). A comparison of the two most prominent factors in 1994 and 1996 showed the process of change to be stronger for 18.2% and weaker for 30% of the variance

  9. Near-surface residual stresses and microstructural changes after turning of a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Schlauer, Christian

    2003-07-01

    Nickel-based superalloys are precipitation hardened alloys with complex compositions. They are used in aircraft engines and land-based gas turbines in load bearing structural components that are exposed to high temperatures. Failure mechanisms in this environment are high and low cycle fatigue, creep, and corrosion. During manufacturing, residual stresses are often introduced into the material due to inhomogeneous plastic deformations, both intentionally and unintentionally. One such manufacturing process is metal cutting, which introduces residual stresses in the surface layer. The stress state in the near-surface zone of components is of special interest as the surface often experiences peak loads and cracks have their starting point there. In this thesis, near-surface residual stress distributions and microstructural changes are studied in the nickel-based superalloy Inconel 718 for two different turning operations, face grooving and facing. Process variables are in both cases cutting speed and feed that have been varied between (10 and 1200) m/min and (0.01 and 0.5) mm, respectively. The first turning technique face grooving, which gives cutting conditions similar to orthogonal cutting, showed a clear dependency of the residual stresses on the cutting speed. The tensile stress at the surface, the maximum compressive stress below the surface, and the thickness of the affected layer increase with increasing cutting speed. The tensile stresses are constrained to a thin surface layer and compressive residual stresses below the surface dominate the depth profile of the residual stresses. Only at low cutting speed, residual stresses were largely avoided. The second turning technique facing confirmed the dependency of the residual stresses on the cutting speed and revealed a similar dependency on the feed. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic

  10. Surface Finish and Residual Stresses Induced by Orthogonal Dry Machining of AA7075-T651

    Directory of Open Access Journals (Sweden)

    Walid Jomaa

    2014-02-01

    Full Text Available The surface finish was extensively studied in usual machining processes (turning, milling, and drilling. For these processes, the surface finish is strongly influenced by the cutting feed and the tool nose radius. However, a basic understanding of tool/surface finish interaction and residual stress generation has been lacking. This paper aims to investigate the surface finish and residual stresses under the orthogonal cutting since it can provide this information by avoiding the effect of the tool nose radius. The orthogonal machining of AA7075-T651 alloy through a series of cutting experiments was performed under dry conditions. Surface finish was studied using height and amplitude distribution roughness parameters. SEM and EDS were used to analyze surface damage and built-up edge (BUE formation. An analysis of the surface topography showed that the surface roughness was sensitive to changes in cutting parameters. It was found that the formation of BUE and the interaction between the tool edge and the iron-rich intermetallic particles play a determinant role in controlling the surface finish during dry orthogonal machining of the AA7075-T651 alloy. Hoop stress was predominantly compressive on the surface and tended to be tensile with increased cutting speed. The reverse occurred for the surface axial stress. The smaller the cutting feed, the greater is the effect of cutting speed on both axial and hoop stresses. By controlling the cutting speed and feed, it is possible to generate a benchmark residual stress state and good surface finish using dry machining.

  11. Low-Stress Silicon Cladding for Surface Finishing Large UVOIR Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase I research, ZeCoat Corporation demonstrated a low-stress silicon cladding process for surface finishing large UVOIR mirrors. A polishable cladding is...

  12. Residual stresses in the surface layer of laser-treated steels

    NARCIS (Netherlands)

    Brussel, B.A. van; Hosson, J.Th.M. De

    1993-01-01

    Although laser treatment of certain metals may enhance the wear performance in general it may result equally well in large residual stresses which affect the wear performance detrimentally. Tensile stresses generated in the surface layer may lead to severe cracking of the material. This paper

  13. The Influence of Pressure Distribution on the Maximum Values of Stress in FEM Analysis of Plain Bearings

    Directory of Open Access Journals (Sweden)

    Vasile Cojocaru

    2016-12-01

    Full Text Available Several methods can be used in the FEM studies to apply the loads on a plain bearing. The paper presents a comparative analysis of maximum stress obtained for three loading scenarios: resultant force applied on the shaft – bearing assembly, variable pressure with sinusoidal distribution applied on the bearing surface, variable pressure with parabolic distribution applied on the bearing surface.

  14. Modelling of composition and stress profiles in low temperature surface engineered stainless steel

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard; Hattel, Jesper Henri; Somers, Marcel A. J.

    2015-01-01

    stresses are introduced in the developing case, arising from the volume expansion that accompanies the dissolution of high interstitial contents in expanded austenite. Modelling of the composition and stress profiles developing during low temperature surface engineering from the processing parameters...... temperature, time and gas composition is a prerequisite for targeted process optimization. A realistic model to simulate the developing case has to take the following influences on composition and stress into account: - a concentration dependent diffusion coefficient - trapping of nitrogen by chromium atoms...... - the effect of residual stress on diffusive flux - the effect of residual stress on solubility of interstitials - plastic accommodation of residual stress. The effect of all these contributions on composition and stress profiles will be addressed....

  15. Stress-related growth following sport injury: Examining the applicability of the organismic valuing theory.

    Science.gov (United States)

    Wadey, R; Podlog, L; Galli, N; Mellalieu, S D

    2016-10-01

    This study explored the applicability of organismic valuing theory (OVT) to stress-related growth (SRG) following sport injury. Specifically, the direct and indirect relationships between need satisfaction (i.e., autonomy, competence, and relatedness), SRG, and subjective well-being (i.e., positive affect) were examined. Previously injured athletes (n = 520), ranging from 18 to 59 years of age (Mage  = 23.3 years; standard deviation = 6.5), completed three measures: needs satisfaction scale, stress-related growth scale, and positive affect scale. Structural equation modeling with maximum likelihood estimation revealed a significant positive relationship between competence and relatedness and SRG, and between SRG and positive affect. In line with OVT, SRG was also found to mediate the relationship between need satisfaction (competence and relatedness) and subjective well-being. The findings offer preliminary support for the applicability of OVT in aiding our understanding of the antecedents and consequences of SRG. Future avenues of research are discussed, together with recommended methodologies to further extend and refine knowledge and understanding of the phenomenon of SRG following sport injury.

  16. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2017-02-01

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate’s longitudinal modulus {β\\text{Ar,\\text{ads}}} on the adsorption-induced normal pressure, Δ {{p}\\text{S}} , which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, Δ p\\text{S}\\text{sat} , and thereby changes of the surface stress {{≤ft(Δ f\\right)}\\text{sat}} at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius {{r}\\text{P}}=3.8 nm) the ultrasonic method reveals a value for Δ p\\text{S}\\text{sat} that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  17. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores.

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2017-02-15

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate's longitudinal modulus [Formula: see text] on the adsorption-induced normal pressure, [Formula: see text], which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, [Formula: see text], and thereby changes of the surface stress [Formula: see text] at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius [Formula: see text] nm) the ultrasonic method reveals a value for [Formula: see text] that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  18. [Research on the spectral feature and identification of the surface vegetation stressed by stored CO2 underground leakage].

    Science.gov (United States)

    Chen, Yun-Hao; Jiang, Jin-Bao; Steven, Michael D; Gong, A-Du; Li, Yi-Fan

    2012-07-01

    With the global climate warming, reducing greenhouse gas emissions becomes a focused problem for the world. The carbon capture and storage (CCS) techniques could mitigate CO2 into atmosphere, but there is a risk in case that the CO2 leaks from underground. The objective of this paper is to study the chlorophyll contents (SPAD value), relative water contents (RWC) and leaf spectra changing features of beetroot under CO2 leakage stress through field experiment. The result shows that the chlorophyll contents and RWC of beetroot under CO2 leakage stress become lower than the control beetroot', and the leaf reflectance increases in the 550 nm region and decreases in the 680nm region. A new vegetation index (R550/R680) was designed for identifying beetroot under CO2 leakage stress, and the result indicates that the vegetation index R550/R680 could identify the beetroots after CO2 leakage for 7 days. The index has strong sensitivity, stability and identification for monitoring the beetroots under CO2 stress. The result of this paper has very important meaning and application values for selecting spots of CCS project, monitoring and evaluating land-surface ecology under CO2 stress and monitoring the leakage spots by using remote sensing.

  19. ANALYSIS OF THE VALUES OF OXIDATIVE STRESS PARAMETERS IN SALIVA OF CHILDREN WITH GINGIVITIS

    Directory of Open Access Journals (Sweden)

    Olivera Tričković-Janjić

    2016-06-01

    Full Text Available Early detection and analysis of the values of the parameters of oxidative stress, malondialdehyde (MDA and reactive carbonyl groups (RCG in saliva, as possible biochemical markers in the diagnosis and prognosis of periodontal disease, may be of particular importance in children. For this reason, the aim of this study was to examine the levels of lipoproteins in the saliva of children without gingivitis and with gingivitis, as well as the degree of gingival inflammation. The testing was conducted in 120 children aged 12.2 years, with permanent dentition. Gingival index by Löe-Silness was used for the gingival estimation. A modified method with thiobarbituric acid was used for the determination of MDA in unstimulated saliva. Colorimetric reaction with 2.4 dinitrophenylhydrazine (2.4 DNPH was applied for the determination of RCG. Results of the analysis of the average values of prooxidizer in the saliva of the patients in a study and the control group showed as statistically significantly higher in the patients of the study group, in RCG concentration (UMW=667.5, z=-4.137, p<0.001 as well as in the level of MDA (UMW=452.5, z=-5.44, p<0.001. The results of the analysis of the MDA level showed an increase in average values with increasing degree of gingival inflammation with statistical significance between the groups confirmed by the KruskalWallis test (χ2 KW=32.45, p<0.001 but not by the Mann-Whitney test. Results of the analysis of concentration of carbonyl groups in patients with varying degrees of gingival inflammation showed an increase with statistically significant differences in the values of this parameter among all groups of patients (χ2 KW=45.23, p<0.001 and by the MannWhitney test the highest among the patients with healthy gingiva and patients with severe gingival inflammation (UMW=113.00, z=-4.98, p<0.001. The presence and increase in the parameters of oxidative stress of malondialdehyde and carbonyl groups in the saliva of children

  20. Residential surface soil guidance values applied worldwide to the original 2001 Stockholm Convention POP pesticides.

    Science.gov (United States)

    Jennings, Aaron A; Li, Zijian

    2015-09-01

    Surface soil contamination is a worldwide problem. Many regulatory jurisdictions attempt to control human exposures with regulatory guidance values (RGVs) that specify a soil's maximum allowable concentration. Pesticides are important soil contaminants because of their intentional toxicity and widespread surface soil application. Worldwide, at least 174 regulatory jurisdictions from 54 United Nations member states have published more than 19,400 pesticide RGVs for at least 739 chemically unique pesticides. This manuscript examines the variability of the guidance values that are applied worldwide to the original 2001 Stockholm Convention persistent organic pollutants (POP) pesticides (Aldrin, Chlordane, DDT, Dieldrin, Endrin, Heptachlor, Mirex, and Toxaphene) for which at least 1667 RGVs have been promulgated. Results indicate that the spans of the RGVs applied to each of these pesticides vary from 6.1 orders of magnitude for Toxaphene to 10.0 orders of magnitude for Mirex. The distribution of values across these value spans resembles the distribution of lognormal random variables, but also contain non-random value clusters. Approximately 40% of all the POP RGVs fall within uncertainty bounds computed from the U.S. Environmental Protection Agency (USEPA) RGV cancer risk model. Another 22% of the values fall within uncertainty bounds computed from the USEPA's non-cancer risk model, but the cancer risk calculations yield the binding (lowest) value for all POP pesticides except Endrin. The results presented emphasize the continued need to rationalize the RGVs applied worldwide to important soil contaminants.

  1. Local stresses, dyke arrest and surface deformation in volcanic edificesand rift zones

    Directory of Open Access Journals (Sweden)

    L. S. Brenner

    2004-06-01

    Full Text Available Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes that are opened by magmatic overpressure. While (inferred dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear strength while the same strength is not exceeded at the (arrested dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses, layers with relatively high dyke-normal compressive stresses (stress barriers, and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward

  2. Diminishing of the mutual influencing in the transformers of mechanical values on surface acoustic waves

    Directory of Open Access Journals (Sweden)

    V. V. Piddubnyi

    2010-01-01

    Full Text Available Normal 0 false false false RU X-NONE X-NONE MicrosoftInternetExplorer4 Examined the problems usage differential amplifier as an active part of the secondary transformer mechanical values in the electrical signal to the surface acoustic wave. Description and results of his researches is resulted.

  3. Effect of shot peening and grit blasting on surface integrity: Influence on residual stresses

    Institute of Scientific and Technical Information of China (English)

    K.TOSHA; LU Jian

    2006-01-01

    The influences of factors such as particle size (0.55-2.2 mm), particle velocity (15-35 m/s) and thickness of work material on the surface integrity were investigated. The residual stresses induced by shot peening or grit blasting were examined. In order to clarify the influences of those factors on residual stress included in the surface integrity, a medium carbon steel (w(C)= 0.45%, 180 HV) was peened by a centrifugal type peening machine using cast steel particles (650-800 HV). The results show that the compressive residual stresses on the peened surface are larger than those of grit blasting; the critical thickness of shot peening is about 50% thicker than that of grit blasting; the high compressive stresses induced by blasting are owing to the wrought or peening effect.

  4. Evaluation of near-surface stress distributions in dissimilar welded joint by scanning acoustic microscopy.

    Science.gov (United States)

    Kwak, Dong Ryul; Yoshida, Sanichiro; Sasaki, Tomohiro; Todd, Judith A; Park, Ik Keun

    2016-04-01

    This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints.

  5. Surface mechanical property and residual stress of peened nickel-aluminum bronze determined by in-situ X-ray diffraction

    Science.gov (United States)

    Wang, Chengxi; Jiang, Chuanhai; Zhao, Yuantao; Chen, Ming; Ji, Vincent

    2017-10-01

    As one of the most important surface strengthening method, shot peening is widely used to improve the fatigue and stress corrosion crack resistance of components by introducing the refined microstructure and compressive residual stress in the surface layer. However, the mechanical properties of this thin layer are different from the base metal and are difficult to be characterized by conventional techniques. In this work, a micro uniaxial tensile tester equipped with in-situ X-ray stress analyzer was employed to make it achievable on a nickel-aluminum bronze with shot peening treatment. According to the equivalent stress-strain relationship based on Von Mises stress criterion, the Young's modulus and yield strength of the peened layer were calculated. The results showed that the Young's modulus was the same as the bulk material, and the yield strength corresponding to the permanent plastic strain of 0.2% was increased by 21% after SP. But the fractographic analysis showed that the fracture feature of the surface layer was likely to transform from the dimple to the cleavage, indicating the improved strength might be attained at the expense of ductility. The monotonic and cyclic loading were also performed via the same combined set-up. In addition, the specific relaxation behavior of compressive residual stress was quantified by linear logarithm relationship between residual stress and cycle numbers. It was found that the compressive residual stress mainly relaxed in the first few cycles, and then reached steady state with further cycles. The relaxation rate and the stable value were chiefly depended on the stress amplitude and number of cycles. The retained residual stress kept in compressive under all given applied stress levels, suggesting that the shot peening could introduce a more stable surface layer of compressive residual stress other than the elevated strength of nickel-aluminum bronze alloy.

  6. Stress distribution and surface instability of an inclined granular layer

    Institute of Scientific and Technical Information of China (English)

    Zheng He-Peng; Jiang Yi-Min; Peng Zheng

    2013-01-01

    Static granular materials may avalanche suddenly under continuous quasi-static drives.This phenomenon,which is important in many engineering applications,can be explained by analyzing the stability of the elastic solutions.We show this for a granular layer driven by its inclination angle in gravity,where the elastic problem can be solved generally and analytically.It is found that a loss of stability may occur only at the free surface of the layer.This result is considered to be relevant for understanding surface avalanches and the flows observed experimentally.

  7. Towards quantifying horizontal stresses of free-polling pneumatic rubber tyres on road surfaces

    CSIR Research Space (South Africa)

    De Beer, Morris

    2008-07-01

    Full Text Available Multi-dimensional forces (and stresses) inside the contact patch of a freerolling pneumatic rubber tyre generally occur as a direct result of a complex interaction between flexible rubber and a rigid test surface or road surface. These forces...

  8. Three-dimensional analysis of elastic stress distribution of indented ceramic surface by finite element method

    Institute of Scientific and Technical Information of China (English)

    Tatsuyuki NEZU

    2006-01-01

    The three-dimensional stress distributions in the area surrounding indentation pattern for three different materials,Al2O3,Si3N4 and SiC were analyzed by finite element method(FEM). Those theoretical results were also compared with the experimental ones by Rockwell hardness test. The effect of loading stress on the plastic deformation in specimens,surface was investigated on the assumption of shear strain energy theory by Huber-Mises when the materials were indented. The distributions of nomal stress,shear stress,and Mises stress were analysed with variations of loading conditions. It is clear that the analytical results for the stress distributions,the crack length and its density of probability are in good agreement with the experimental results.

  9. The Friction Law Stress Exponent under Pine Island Glacier from 15 Years of Surface Elevation and Velocity Measurements

    Science.gov (United States)

    Gillet-chaulet, F.; Durand, G.; Gagliardini, O.; Mosbeux, C.; Mouginot, J.; Remy, F.; Ritz, C.

    2015-12-01

    Polar the ice-sheets mass balance largely depends on the flow of ice-streams. Rapid basal motion generally accounts for most of the velocities. In flow models, the conditions at the base of the ice in contact with the bedrock are generally parameterised using a friction law that relates the sliding velocity to the basal shear stress. The most common law has two poorly constrained parameters, the basal slipperiness c and the stress exponent m. The basal slipperiness is expected to depend on local unobservable quantities and is routinely tuned from observed surface velocities using inverse methods. Different values for m are expected depending on the processes, from hard-bed sliding to soft bed deformation, and no consensus has emerged so far for its value that range from 1 to infinity. However, several studies have shown that the transient response of the ice-sheet models to external forcing is highly sensitive to m. Therefore, the uncertainty attached to the friction law is an important limit to our ability to evaluate future dynamical evolution of coastal regions. Calibrating m can be done only if either basal stresses and/or velocities have changed significantly while c can be assumed constant in time. Here, we use Elmer/Ice to model the flow of Pine Island Glacier (PIG), Antarctica, sufficiently far upstream of the grounding line so that we can assume no change in c. Observations show an increase of surface velocities by up to 50% between 1996 and 2010, associated with an important dynamical thinning. Using a control inverse method and different values of m, we tune a spatially varying basal slipperiness field that best fit, in the same time, observed surface velocities for years 1996, 2007, 2008, 2009 and 2010. These years correspond to the MeaSUREs project velocity datasets that have the best spatial coverage for our model domain. Surface elevations for the corresponding years are constructed using ERS and Envisat radar altimetry data. We show that the

  10. Stresses and strains developed by the reflection of seismic waves at a free surface

    Energy Technology Data Exchange (ETDEWEB)

    Banister, J.R.; Ellett, D.M.; Mehl, C.R.; Dean, F.F.

    1978-07-01

    Exact and approximate equations have been derived for the stresses and strains beneath a free surface when an incoming longitudinal wave and an incoming shear wave reflect from the surface. Results of the approximate solution for depths much less than the wave length of the incoming wave are given in tabular form and are graphed for Poisson's ratios of 0.25, 0.3, and 0.333. The results should be of use in categorizing the magnitude of near-surface stresses and strains resulting from seismic waves produced by deeply buried explosives or earthquakes.

  11. A One-Layer Satellite Surface Energy Balance for Estimating Evapotranspiration Rates and Crop Water Stress Indexes

    Directory of Open Access Journals (Sweden)

    Salvatore Barbagallo

    2009-01-01

    Full Text Available Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (rah is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (rs is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i data from the semi-empirical approach “Kc reflectance-based”, which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations.

  12. Surface Wave Speed of Functionally Graded Magneto-Electro-Elastic Materials with Initial Stresses

    Directory of Open Access Journals (Sweden)

    Li Li

    2014-09-01

    Full Text Available The shear surface wave at the free traction surface of half- infinite functionally graded magneto-electro-elastic material with initial stress is investigated. The material parameters are assumed to vary ex- ponentially along the thickness direction, only. The velocity equations of shear surface wave are derived on the electrically or magnetically open circuit and short circuit boundary conditions, based on the equations of motion of the graded magneto-electro-elastic material with the initial stresses and the free traction boundary conditions. The dispersive curves are obtained numerically and the influences of the initial stresses and the material gradient index on the dispersive curves are discussed. The investigation provides a basis for the development of new functionally graded magneto-electro-elastic surface wave devices.

  13. Engineering the residual stress state and microstructure of stainless steel with mechanical surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Turski, M.; Clitheroe, S.; Withers, P.J. [Manchester University, School of Materials, Manchester (United Kingdom); Evans, A.D. [Paul Scherrer Institut, Villigen-PSI (Switzerland); Rodopoulos, C. [University of Patras, Patras (Greece); Hughes, D.J. [Institut Laue Langevin, Grenoble (France)

    2010-06-15

    Four mechanical surface treatments have been considered for the application to austenitic stainless steel structures. Shot peening (SP), laser shock peening (LSP), ultrasonic impact treatment (UIT) and water jet cavitation peening (WJCP), also known as cavitation shotless peening (CSP), have been applied to 8 mm thick Type 304 austenitic stainless steel coupons. This study considers the merits of each of these mechanical surface treatments in terms of their effect on the surface roughness, microstructure, level of plastic work and through thickness residual stress distribution. Microstructural studies have revealed the formation of martensite close to the treated surface for each process. Residual stress measurements in the samples show compressive stresses to a significantly greater depth for the LSP, UIT and WJCP samples compared to the more conventional SP treated sample. (orig.)

  14. Influence of fractality of fracture surfaces on stress and displacement fields at crack tips

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the classic theory of fracture mechanics,expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth crack.In fact,the surface of a crack formed during the fracture is usually very irregular.So the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic one.Considering the irregularity of a real fracture surface or a real crack profile,the crack is taken as a fractal one,and then the real asymptotic form at the crack tip is developed by applying Griffith’s energy balance principle and fractal geometry.Through the developed asymptotic form,it is discovered that the fractality of the crack reduces the stress singularity at the crack tip.

  15. Research on Haze Value of Wafer Surface%晶片表面Haze值研究

    Institute of Scientific and Technical Information of China (English)

    张伟才; 宋晶; 杨洪星; 赵权

    2011-01-01

    The Haze value of wafer surface is introduced from the definitions and theories based on the principle of SSIS. The Haze is explained as optical signals which can indirectly reflect the state of the wafer surface. The different materials and different surface were scanned by SSIS, and the effect of surface roughness and reflection coefficient on the Haze value and its distribution were studied. The results show that the Haze value of the same material increases with the increase of surface roughness, and the Haze value shows significant differences between different materials with similar roughness. Through the Analysis of the characteristics of scans, the relationship between Haze value distribution and the consistency of wafer surface state was studied. A new process feedback method for chemical mechanical polishing and wet cleaning process using Haze value was proposed.%介绍了晶片表面Haze值的定义和理论依据,通过对SSIS系统的原理分析,揭示了H aze是一种间接反映晶片表面状态的光学信号.通过对不同表面状态抛光片的光学扫描,研究了晶片表面粗糙度与Haze值的关系;通过对Si抛光片和砷化镓抛光片的扫描对比,研究了晶片本体反射系数对Haze值的影响.研究结果表明,同种材料的Haze值随着表面粗糙度的增大而增大,而不同的材料即使拥有相似的表面粗糙度,Haze值也会因本体反射系数的不同而呈现很大差异.通过对Haze扫描图的特征分析,研究了Haze值分布与晶片表面均匀性的关系,成功地利用Haze值分布将表面性状化,为化学机械抛光和湿法清洗工艺提供了一个新的反馈手段.

  16. Estimation of the shear stress on the surface of an aortic valve leaflet.

    Science.gov (United States)

    Weston, M W; LaBorde, D V; Yoganathan, A P

    1999-01-01

    The limited durability of xenograft heart valves and the limited supply of allografts have sparked interest in tissue engineered replacement valves. A bioreactor for tissue engineered valves must operate at conditions that optimize the biosynthetic abilities of seeded cells while promoting their adherence to the leaflet matrix. An important parameter is shear stress, which is known to influence cellular behavior and may thus be crucial in bioreactor optimization. Therefore, an accurate estimate of the shear stress on the leaflet surface would not only improve our understanding of the mechanical environment of aortic valve leaflets, but it would also aid in bioreactor design. To estimate the shear stress on the leaflet surface, two-component laser-Doppler velocimetry measurements have been conducted inside a transparent polyurethane valve with a trileaflet structure similar to the native aortic valve. Steady flow rates of 7.5, 15.0, and 22.5 L/min were examined to cover the complete range possible during the cardiac cycle. The laminar shear stresses were calculated by linear regression of four axial velocity measurements near the surface of the leaflet. The maximum shear stress recorded was 79 dyne/cm2, in agreement with boundary layer theory and previous experimental and computational studies. This study has provided a range of shear stresses to be explored in bioreactor design and has defined a maximum shear stress at which cells must remain adherent upon a tissue engineered construct.

  17. Evaluation of Residual Stress Relaxation in Surface-Treated Engine Alloys

    Science.gov (United States)

    2008-06-01

    account for the inevitable stress release during this process. This method is inherently destructive since it leaves a deep hole on the surface...accelerator or a nuclear reactor. 3 Surface enhancement methods, such as shot peening, laser shock peening, and low- plasticity burnishing , significantly...peening, laser shock peening, or low-plasticity burnishing , surface treatment also leaves substantial microstructural damage behind in the material

  18. Thermally induced stresses in boulders on airless body surfaces, and implications for rock breakdown

    Science.gov (United States)

    Molaro, J. L.; Byrne, S.; Le, J.-L.

    2017-09-01

    This work investigates the macroscopic thermomechanical behavior of lunar boulders by modeling their response to diurnal thermal forcing. Our results reveal a bimodal, spatiotemporally-complex stress response. During sunrise, stresses occur in the boulders' interiors that are associated with large-scale temperature gradients developed due to overnight cooling. During sunset, stresses occur at the boulders' exteriors due to the cooling and contraction of the surface. Both kinds of stresses are on the order of 10 MPa in 1 m boulders and decrease for smaller diameters, suggesting that larger boulders break down more quickly. Boulders ≤ 30 cm exhibit a weak response to thermal forcing, suggesting a threshold below which crack propagation may not occur. Boulders of any size buried by regolith are shielded from thermal breakdown. As boulders increase in size (>1 m), stresses increase to several 10 s of MPa as the behavior of their surfaces approaches that of an infinite halfspace. As the thermal wave loses contact with the boulder interior, stresses become limited to the near-surface. This suggests that the survival time of a boulder is not only controlled by the amplitude of induced stress, but also by its diameter as compared to the diurnal skin depth. While stresses on the order of 10 MPa are enough to drive crack propagation in terrestrial environments, crack propagation rates in vacuum are not well constrained. We explore the relationship between boulder size, stress, and the direction of crack propagation, and discuss the implications for the relative breakdown rates and estimated lifetimes of boulders on airless body surfaces.

  19. Incremental Prognostic Value of Stress Echocardiography With Carotid Ultrasound for Suspected CAD.

    Science.gov (United States)

    Ahmadvazir, Shahram; Shah, Benoy N; Zacharias, Konstantinos; Senior, Roxy

    2017-04-07

    This study hypothesized that ischemia and atherosclerosis assessment by ultrasound (US) may provide incremental prognostic information in patients with new-onset chest pain who do not have coronary artery disease (CAD). The clinical significance of atherosclerosis assessment by carotid US in patients undergoing stress echocardiography (SE) in such patients is unknown. Consecutive patients with suspected angina but no history of CAD underwent simultaneous SE and US prospectively to assess myocardial ischemia and carotid plaque burden (CPB), respectively. Patients were followed up for major adverse events (MAEs)-all-cause mortality, nonfatal myocardial infarction, and unplanned coronary revascularization. Of 591 recruited patients, 580 (men, 46%; mean age 59 ± 11 years) patients were available for follow-up. SE demonstrated myocardial ischemia in 12%, but prevalence of carotid plaques was 59%. During a mean follow-up of 1,117 ± 361 days, 40 first MAEs occurred. In the multivariable regression model, pre-test probability (PTP) of CAD (p = 0.001), abnormal SE (p CAD and SE; likewise, SE was incremental to PTP-CAD and CPB (p CAD, simultaneous SE (for ischemia) and US (for atherosclerosis) provided incremental prognostic value. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  20. Portable microsystem integrates multifunctional dielectrophoresis manipulations and a surface stress biosensor to detect red blood cells for hemolytic anemia.

    Science.gov (United States)

    Sang, Shengbo; Feng, Qiliang; Jian, Aoqun; Li, Huiming; Ji, Jianlong; Duan, Qianqian; Zhang, Wendong; Wang, Tao

    2016-09-20

    Hemolytic anemia intensity has been suggested as a vital factor for the growth of certain clinical complications of sickle cell disease. However, there is no effective and rapid diagnostic method. As a powerful platform for bio-particles testing, biosensors integrated with microfluidics offer great potential for a new generation of portable point of care systems. In this paper, we describe a novel portable microsystem consisting of a multifunctional dielectrophoresis manipulations (MDM) device and a surface stress biosensor to separate and detect red blood cells (RBCs) for diagnosis of hemolytic anemia. The peripheral circuit to power the interdigitated electrode array of the MDM device and the surface stress biosensor test platform were integrated into a portable signal system. The MDM includes a preparing region, a focusing region, and a sorting region. Simulation and experimental results show the RBCs trajectories when they are subjected to the positive DEP force, allowing the successful sorting of living/dead RBCs. Separated RBCs are then transported to the biosensor and the capacitance values resulting from the variation of surface stress were measured. The diagnosis of hemolytic anemia can be realized by detecting RBCs and the portable microsystem provides the assessment to the hemolytic anemia patient.

  1. Diagnostic value of 3 D CT surface reconstruction in spinal fractures

    Energy Technology Data Exchange (ETDEWEB)

    Koesling, S. [Department of Radiology, Univ. of Leipzig (Germany); Dietrich, K. [Department of Radiology, Univ. of Leipzig (Germany); Steinecke, R. [Department of Radiology, Univ. of Leipzig (Germany); Kloeppel, R. [Department of Radiology, Univ. of Leipzig (Germany); Schulz, H.G. [Department of Radiology, Univ. of Leipzig (Germany)

    1997-02-01

    Our purpose was to evaluate the diagnostic value of three-dimensional (3 D) CT surface reconstruction in spinal fractures in comparison with axial and reformatted images. A total of 50 patients with different CT-proven spinal fractures were analysed retrospectively. Based on axial scans and reformatted images, the spinal fractures were classified according to several classifications as Magerl for the thoraco-lumbar and lower cervical spine by one radiologist. Another radiologist performed 3 D CT surface reconstructions with the aim of characterizing the different types of spinal fractures. A third radiologist classified the 3 D CT surface reconstruction according to the Magerl classification. The results of the blinded reading process were compared. It was checked to see in which type and subgroup 3 D surface reconstructions were helpful. Readers one and two obtained the same results in the classification. The 3 D surface reconstruction did not yield any additional diagnostic information concerning type A and B injuries. Indeed, the full extent of the fracture could be easier recognized with axial and reformatted images in all cases. In 10 cases of C injuries, the dislocation of parts of vertebrae could be better recognized with the help of 3 D reconstructions. A 3 D CT surface reconstruction is only useful in rotational and shear vertebral injuries (Magerl type C injury). (orig.). With 4 figs., 1 tab.

  2. Recoverable stress induced two-way shape memory effect on NiTi surface using laser-produced shock wave

    Science.gov (United States)

    Seyitliyev, Dovletgeldi; Li, Peizhen; Kholikov, Khomidkhodza; Grant, Byron; Thomas, Zachary; Alal, Orhan; Karaca, Haluk E.; Er, Ali O.

    2017-02-01

    The surfaces of Ni50Ti50 shape memory alloys (SMAs) were patterned by laser scribing. This method is more simplistic and efficient than traditional indentation techniques, and has also shown to be an effective method in patterning these materials. Different laser energy densities ranging from 5 mJ/pulse to 56 mJ/pulse were used to observe recovery on SMA surface. The temperature dependent heat profiles of the NiTi surfaces after laser scribing at 56 mJ/pulse show the partially-recovered indents, which indicate a "shape memory effect (SME)" Experimental data is in good agreement with theoretical simulation of laser induced shock wave propagation inside NiTi SMAs. Stress wave closely followed the rise time of the laser pulse to its peak values and initial decay. Further investigations are underway to improve the SME such that the indents are recovered to a greater extent.

  3. Determination of stress glut moments of total degree 2 from teleseismic surface wave amplitude spectra

    Science.gov (United States)

    Bukchin, B. G.

    1995-08-01

    A special case of the seismic source, where the stress glut tensor can be expressed as a product of a uniform moment tensor and a scalar function of spatial coordinates and time, is considered. For such a source, a technique of determining stress glut moments of total degree 2 from surface wave amplitude spectra is described. The results of application of this technique for the estimation of spatio-temporal characteristics of the Georgian earthquake, 29.04.91 are presented.

  4. Quantification of the surface stress in microcantilever biosensors: revisiting Stoney’s equation

    Science.gov (United States)

    Tamayo, Javier; Ruz, Jose J.; Pini, Valerio; Kosaka, Priscila; Calleja, Montserrat

    2012-11-01

    Microcantilever biosensors in the static operation mode translate molecular recognition into a surface stress signal. Surface stress is derived from the nanomechanical cantilever bending by applying Stoney’s equation, derived more than 100 years ago. This equation ignores the clamping effect on the cantilever deformation, which induces significant errors in the quantification of the biosensing response. This leads to discrepancies in the surface stress induced by biomolecular interactions in measurements with cantilevers with different sizes and geometries. So far, more accurate solutions have been precluded by the formidable complexity of the theoretical problem that involves solving the two-dimensional biharmonic equation. In this paper, we present an accurate and simple analytical expression to quantify the response of microcantilever biosensors. The equation exhibits an excellent agreement with finite element simulations and DNA immobilization experiments on gold-coated microcantilevers.

  5. Effects of Stress Work on MHD Natural Convection Flow along a Vertical Wavy Surface with Joule Heating

    Directory of Open Access Journals (Sweden)

    Kazi Humayun Kabir

    2015-01-01

    Full Text Available An analysis is presented to investigate the influences of viscous and pressure stress work on MHD natural convection flow along a uniformly heated vertical wavy surface. The governing equations are first modified and then transformed into dimensionless non-similar equations by using set of suitable transformations. The transformed boundary layer equations are solved numerically using the implicit finite difference method, known as Keller-box scheme. Numerical results for the velocity profiles, temperature profiles, skin friction coefficient, the rate of heat transfers, streamlines and isotherms are shown graphically. Some results of skin friction, rate of heat transfer are presented in tabular form for selected values of physical parameters.

  6. Trends in Extremes of Surface Humidity, Temperature, and Summertime Heat Stress in China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the past half century, the mean summertime temperature in China has increased, with nights warm ing more than days. Using surface station observations, we show that the frequency of extreme heat-stress events in China, caused by extremely hot and humid days as well as by heatwaves lasting for a few days, has increased over the period from 1951 to 1994. When humidity is high, hot weather can cause heat stress in humans. The increased heat-stress trend may pose a public health problem.

  7. Instantaneous stress release in fault surface asperities during mining-induced fault-slip

    Institute of Scientific and Technical Information of China (English)

    Atsushi Sainoki; Hani S. Mitri

    2016-01-01

    Fault-slip taking place in underground mines occasionally causes severe damage to mine openings as a result of strong ground motion induced by seismic waves arising from fault-slip. It is indicated from previous studies that intense seismic waves could be generated with the shock unloading of fault surface asperities during fault-slip. This study investigates the shock unloading with numerical simulation. A three-dimensional (3D) numerical model with idealized asperities is constructed with the help of discrete element code 3DEC. The idealization is conducted to particularly focus on simulating the shock unloading that previous numerical models, which replicate asperity degradation and crack development during the shear behavior of a joint surface in previous studies, fail to capture and simulate. With the numerical model, static and dynamic analyses are carried out to simulate unloading of asperities in the course of fault-slip. The results obtained from the dynamic analysis show that gradual stress release takes place around the center of the asperity tip at a rate of 45 MPa/ms for the base case, while an instantaneous stress release greater than 80 MPa occurs near the periphery of the asperity tip when the contact between the upper and lower asperities is lost. The instantaneous stress release becomes more intense in the vicinity of the asperity tip, causing tensile stress more than 20 MPa. It is deduced that the tensile stress could further increase if the numerical model is discretized more densely and analysis is carried out under stress conditions at a great depth. A model parametric study shows that in-situ stress state has a significant influence on the magnitude of the generated tensile stress. The results imply that the rapid stress release generating extremely high tensile stress on the asperity tip can cause intense seismic waves when it occurs at a great depth.

  8. Validation of surface crack stress intensity factors of a tubular K-joint

    Energy Technology Data Exchange (ETDEWEB)

    Lie, S.T. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)]. E-mail: cstlie@ntu.edu.sg; Lee, C.K. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Chiew, S.P. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Shao, Y.B. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)

    2005-08-01

    Tubular K-joints are encountered widely in offshore structures, and the prediction of damaged joints depends very much on the accuracy of stress intensity factor solutions (SIFs). No parametric equations and very few results have been proposed and published in the literature for estimating the SIFs of any K-joints subjected to complex loading conditions. In this paper, a mesh generation method proposed previously for the Y-joint and T-joint has been extended to the K-joint. This method is realized by dividing the K-joint into several sub-zones with each zone consisting of different types of elements and mesh densities. This method has a distinct advantage of controlling the mesh quality, and most importantly the aspect ratio of the elements along the crack front. When the mesh of all the sub-zones has been generated automatically and completely, they are merged to form the complete model. The two most commonly used methods, namely the J-integral and displacement extrapolation, are used to evaluate the SIF values along the crack front of a typical K-joint. To validate the accuracy of these computed SIFs, a full-scale K-joint specimen was tested to failure under fatigue loading conditions. The standard alternating current potential drop (ACPD) technique was used to monitor the rate of crack propagation of the surface crack located at the hot spot stress region. Using the given material parameters C and m, the experimental SIFs were deduced, and they are found to be in good agreement with the computed SIFs obtained from the generated models. Hence, the proposed finite element models are both efficient and reliable.

  9. A thin rivulet or ridge subject to a uniform transverse shear stress at its free surface due to an external airflow

    KAUST Repository

    Sullivan, J. M.

    2012-01-01

    We use the lubrication approximation to analyze three closely related problems involving a thin rivulet or ridge (i.e., a two-dimensional droplet) of fluid subject to a prescribed uniform transverse shear stress at its free surface due to an external airflow, namely a rivulet draining under gravity down a vertical substrate, a rivulet driven by a longitudinal shear stress at its free surface, and a ridge on a horizontal substrate, and find qualitatively similar behaviour for all three problems. We show that, in agreement with previous numerical studies, the free surface profile of an equilibrium rivulet/ridge with pinned contact lines is skewed as the shear stress is increased from zero, and that there is a maximum value of the shear stress beyond which no solution with prescribed semi-width is possible. In practice, one or both of the contact lines will de-pin before this maximum value of the shear stress is reached, and so we consider situations in which the rivulet/ridge de-pins at one or both contact lines. In the case of de-pinning only at the advancing contact line, the rivulet/ridge is flattened and widened as the shear stress is increased from its critical value, and there is a second maximum value of the shear stress beyond which no solution with a prescribed advancing contact angle is possible. In contrast, in the case of de-pinning only at the receding contact line, the rivulet/ridge is thickened and narrowed as the shear stress is increased from its critical value, and there is a solution with a prescribed receding contact angle for all values of the shear stress. In general, in the case of de-pinning at both contact lines there is a critical "yield" value of the shear stress beyond which no equilibrium solution is possible and the rivulet/ridge will evolve unsteadily. In the Appendix, we show that an equilibrium rivulet/ridge with prescribed flux/area is quasi-statically stable to two-dimensional perturbations. © 2012 American Institute of Physics.

  10. FINITE ELEMENT ANALYSIS ABOUT STRESS AND STRAIN OF SURFACE PEELING IN Cu-Fe-P SHEET

    Institute of Scientific and Technical Information of China (English)

    Su Juanhua; Li Hejun; Dong Qiming; Liu Ping; Kang Buxi

    2005-01-01

    The microstructure of surface peeling in finish rolled Cu-0.1Fe-0.03P sheet is analyzed by scanning electron microscope and energy dispersive spectroscope. Fe-rich areas of different contents are observed in the matrix. The stress distributions and strain characteristics at the interface between Cu matrix and Fe particle are studied by elastic-plastic finite element plane strain model. Larger Fe particles and higher deforming extent of finish rolling are attributed to the intense stress gradient and significant non-homogeneity equivalent strain at the interface and accelerate surface peeling of Cu-0.1Fe-0.03P lead frame sheet.

  11. lnvestigation of Patch Coatings lnfluence on the Stress lntensity Factor for Surface Cracks

    DEFF Research Database (Denmark)

    Lambertsen, Søren Heide; Jepsen, Michael S.; Damkilde, Lars

    2013-01-01

    to damp the free end of the crack, which will reduce the stress intensity factor and subsequently reduce the crack growth. The considered patch consists of a surface layer of 0.2 mm two component adhesive Epoxy, 3M DP 460. The models described in this work contains five different crack sizes with a patch......In this paper, it is investigated how a surface layer of epoxy glue will affect the crack propagation of a surface crack. The intension is to reduce or even stop the crack propagation by means of patch layer coating. When adding a patch layer to the surface with small cracks, the layer will attempt...... layer on the surface. The stress intensity factor is computed by means of the J-integral and the FE-model is setup with a nonlinear material model to establish the upper boundary for the patch stress capacity. A reduction of the stress intensity factor of approximately 2 % and a reduction of the crack...

  12. Surface profile and stress field evaluation using digital gradient sensing method

    Science.gov (United States)

    Miao, C.; Sundaram, B. M.; Huang, L.; Tippur, H. V.

    2016-09-01

    Shape and surface topography evaluation from measured orthogonal slope/gradient data is of considerable engineering significance since many full-field optical sensors and interferometers readily output such a data accurately. This has applications ranging from metrology of optical and electronic elements (lenses, silicon wafers, thin film coatings), surface profile estimation, wave front and shape reconstruction, to name a few. In this context, a new methodology for surface profile and stress field determination based on a recently introduced non-contact, full-field optical method called digital gradient sensing (DGS) capable of measuring small angular deflections of light rays coupled with a robust finite-difference-based least-squares integration (HFLI) scheme in the Southwell configuration is advanced here. The method is demonstrated by evaluating (a) surface profiles of mechanically warped silicon wafers and (b) stress gradients near growing cracks in planar phase objects.

  13. Mathematical study of boundary-value problems within the framework of Steigmann-Ogden model of surface elasticity

    Science.gov (United States)

    Eremeyev, Victor A.; Lebedev, Leonid P.

    2016-03-01

    Mathematical questions pertaining to linear problems of equilibrium dynamics and vibrations of elastic bodies with surface stresses are studied. We extend our earlier results on existence of weak solutions within the Gurtin-Murdoch model to the Steigmann-Ogden model of surface elasticity using techniques from the theory of Sobolev's spaces and methods of functional analysis. The Steigmann-Ogden model accounts for the bending stiffness of the surface film; it is a generalization of the Gurtin-Murdoch model. Weak setups of the problems, based on variational principles formulated, are employed. Some uniqueness-existence theorems for weak solutions of static and dynamic problems are proved in energy spaces via functional analytic methods. On the boundary surface, solutions to the problems under consideration are smoother than those for the corresponding problems of classical linear elasticity and those described by the Gurtin-Murdoch model. The weak setups of eigenvalue problems for elastic bodies with surface stresses are based on the Rayleigh and Courant variational principles. For the problems based on the Steigmann-Ogden model, certain spectral properties are established. In particular, bounds are placed on the eigenfrequencies of an elastic body with surface stresses; these demonstrate the increase in the body rigidity and the eigenfrequencies compared with the situation where the surface stresses are neglected.

  14. Quantitative assessments of residual stress fields at the surface of alumina hip joints.

    Science.gov (United States)

    Pezzotti, Giuseppe; Munisso, Maria Chiara; Lessnau, Kristina; Zhu, Wenliang

    2010-11-01

    In-depth and in-plane response functions of photo- and electro-stimulated probes have been modeled and quantitatively evaluated in order to assess their suitability to detect the highly graded residual stress fields generated at the surface of alumina hip joints. Optical calibrations revealed large differences in probe size, which strongly affected the detected magnitude of residual stress. A comparison between the responses of Raman and fluorescence probes in polycrystalline alumina showed that the depth of those probes spread to an extent in the order of the tens of microns even with using a confocal probe configuration. On the other hand, the electro-stimulated luminescence emitted by oxygen vacancy sites (F(+) center) in the alumina lattice represented the most suitable choice for confining to a shallow volume the stress probe. This latter probe enabled us to reduce the measurement depth to the order of the tens of nanometers. We show maps of surface residual stress as collected on both main-wear and nonwear zones of an alumina femoral head. A comparison among stress maps taken at exactly the same location, but employing different probes, revealed averaging effects on the stress magnitude detected with photo-stimulated probes, while proving the superior spatial resolution of the electron probe.

  15. Residual Stress on Surface and Cross-section of Porous Silicon Studied by Micro-Raman Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LEI Zhen-Kun; KANG YI-Lan; CEN Hao; HU Ming; QIU Yu

    2005-01-01

    @@ Surface and cross-sectional residual stresses of electrochemical etching porous silicon are investigated quantitatively by micro-Raman spectroscopy.The results reveal that a larger tensile residual stress exists on the surface and increase linearly with the porosity.On the other hand, across the depth direction perpendicular to the surface, the tensile residual stress decreases gradually from the surface to regions near the interface between the porous silicon layer and the Si substrate.However, a compressive stress appears at the interface near to the Si substrate for balancing with the tensile stress in the porous silicon layer.The cross-sectional residual stress profile is due to the porosity and lattice mismatch gradients existing in the cross-section and influencing each other.Furthermore, the presented residual stresses of the porous silicon have a close relation with its microstructure.

  16. [The influence of professional values in the emergence of work stress and burn-out in newly graduated nurses].

    Science.gov (United States)

    Rebecchi, E; Benassi, M; Bolzani, R; Santullo, A

    2009-01-01

    The aim of this study is to evaluate the work importance values in nurse population in their first years of employment to analyse if they could change and if they could be considered as predictors of job stress and burn-out which developed during this period. A group of nurses has been analysed at the beginning of their employment and during the first three years concerning the work importance values measured with the Scala dei Valori Professionali (SVP), the job stress factors evaluated with the Job Content Questionnaire (JCQ) and the burn-out measured with Maslach Burn-out Inventory MBI. The work importance values has changed during the first three years of employment. Although also the job situation has changed during this period increasing the stress, these changes are not related to a particular configuration of the work importance values. Nevertheless, the work importance scale has found to be related to a specific burn-out scale, that is emotional exhaustion. In details, the importance given to career development is related to an increase of emotional exhaustion while the importance given to social aspects decreases it. These results suggest that the work importance values evaluated at the beginning of the working period could be considered as predictors of specific burn-out aspects such as those related to emotional exhaustion.

  17. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  18. Realignment of Nanocrystal Aggregates into Single Crystals as a Result of Inherent Surface Stress

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhaoming [Department of Chemistry, Zhejiang University, Hangzhou Zhejiang 310027 China; Pan, Haihua [Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou Zhejiang 310027 China; Zhu, Genxing [Department of Chemistry, Zhejiang University, Hangzhou Zhejiang 310027 China; Li, Yaling [Department of Chemistry, Zhejiang University, Hangzhou Zhejiang 310027 China; Tao, Jinhui [Physical Sciences Division, Pacific Northwest National Laboratory, Richland WA 99354 USA; Jin, Biao [Department of Chemistry, Zhejiang University, Hangzhou Zhejiang 310027 China; Tang, Ruikang [Department of Chemistry, Zhejiang University, Hangzhou Zhejiang 310027 China; Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou Zhejiang 310027 China

    2016-07-19

    Assembly of nanoparticles building blocks during single crystal growth is widely observed in both natural and synthetic environments. Although this form of non-classical crystallization is generally described by oriented attachment, random aggregation of building blocks leading to single crystal products is also observed, but the mechanism of crystallographic realignment is unknown. We herein reveal that random attachment during aggregation-based growth initially produces a non-oriented growth front. Subsequent evolution of the orientation is driven by the inherent surface stress applied by the disordered surface layer and results in single crystal formation via grain boundary migration. This mechanism is corroborated by measurements of orientation rate vs external stress, demonstrating a predictive relationship between the two. These findings advance our understanding of aggregation-based growth of natural minerals by nanocrystals, and suggest an approach to material synthesis that takes advantage of stress induced co-alignment.

  19. Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materials.

    Science.gov (United States)

    1986-03-31

    elimination of ’weakened’ siloxane linkages, the creation of a ’ microplastic ’ surface layer, and consequently a more uniform distribution of applied stress...examined the impact toughness of plate glass treated at elevated temperatures with sulfur dioxide and also difluorodichloromethane. They, too, observed an

  20. Comparison of surface wind stress measurements - Airborne radar scatterometer versus sonic anemometer

    Science.gov (United States)

    Brucks, J. T.; Leming, T. D.; Jones, W. L.

    1980-01-01

    Sea surface wind stress measurements recorded by a sonic anemometer are correlated with airborne scatterometer measurements of ocean roughness (cross section of radar backscatter) to establish the accuracy of remotely sensed data and assist in the definition of geophysical algorithms for the scatterometer sensor aboard Seasat A. Results of this investigation are as follows: Comparison of scatterometer and sonic anemometer wind stress measurements are good for the majority of cases; however, a tendency exists for scatterometer wind stress to be somewhat high for higher wind conditions experienced in this experiment (6-9 m/s). The scatterometer wind speed algorithm tends to overcompute the higher wind speeds by approximately 0.5 m/s. This is a direct result of the scatterometer overestimate of wind stress from which wind speeds are derived. Algorithmic derivations of wind speed and direction are, in most comparisons, within accuracies defined by Seasat A scatterometer sensor specifications.

  1. The influence of surface effect on vibration behaviors of carbon nanotubes under initial stress

    Science.gov (United States)

    Chen, X.; Fang, C. Q.; Wang, X.

    2017-01-01

    An analytical method is presented to solve the influence of surface effect on non-coaxial resonance of multi-walled carbon nanotubes embedded in matrix utilizing laminated structures model. Due to coupled van der Waals forces between adjacent tubes and surface effect exerted carbon nanotubes, the resonance frequencies and amplitude ratios of multi-walled carbon nanotubes under initial stresses show that the resonant characteristics of the multi-walled carbon nanotubes become complex and the numbers of vibrational modes do not keep increase under identical conditions after considering surface effects. The result obtained can be used as a beneficial reference for investigating the electronic and physical behaviors of carbon nanotubes.

  2. Molt-associated changes in hematologic and plasma biochemical values and stress hormone levels in African penguins (Spheniscus demersus).

    Science.gov (United States)

    Mazzaro, Lisa M; Meegan, Jenny; Sarran, Delphine; Romano, Tracy A; Bonato, Vinicius; Deng, Shibing; Dunn, J Lawrence

    2013-12-01

    Handling, including blood collection, has often been discouraged in molting penguins because it is considered an additional stress imposed on birds already experiencing major physiologic stress associated with molting. To evaluate the degree of physiologic stress posed by molting, we compared the hematologic and plasma biochemical values and hormone levels of molting and nonmolting African penguins, Spheniscus demersus. Five male and 5 female penguins randomly chosen were given complete physical examinations, were weighed, and blood samples were taken at 7 time points before, during, and after the molt. Data were analyzed by linear mixed-model analysis of variance. Throughout the study, behavior and appetite remained normal. Catecholamine levels were highly variable within and among subjects, whereas mean corticosterone levels were significantly different between baseline, molt, and postmolt values. Significant differences from baseline values were observed in many of the hematologic analytes; however, only decreases in hematocrit and red blood cell count values were considered clinically significant. Anemia due to experimentally induced blood loss as a possible cause of the significant hematologic changes was ruled out based on results of a follow-up control study during the nonmolt season, which showed no significant changes in hematocrit level or total red blood cell counts when using similar sampling protocols, which indicates that these changes were associated with molt.

  3. Diagnostic value of layer-specific global longitudinal strain during adenosine stress in patients suspected of coronary artery disease.

    Science.gov (United States)

    Ejlersen, June A; Poulsen, Steen H; Mortensen, Jesper; May, Ole

    2017-04-01

    Speckle tracking global longitudinal strain (GLS) from dobutamine stress echocardiography (SE) predicts coronary artery disease (CAD). The diagnostic value of GLS from vasodilator SE and the additional value of layer-specific speckle tracking analysis are unclear. We explored the usefulness of layer-specific GLS and non-layer-specific strain (automated functional imaging, AFI) from adenosine SE. The included 132 patients (67% male, 62.6 (9.0) years), of which 46 (35%) had CAD defined as ≥1 stenosis ≥70% (≥50% in the left main), underwent adenosine SE and invasive coronary angiography. Resting AFI and layer-specific GLS were similar in patients with or without CAD (p > 0.05). The stress-rest difference (Δvalue = stress-value - rest-value) in patients with CAD was less pronounced compared to patients without proved CAD (Δendocardial GLS: -1.2 (3.5)% vs. -5.0 (3.2)%; Δmidventricular GLS: -0.95 (3.0)% vs. -4.2 (2.7)%; Δepicardial GLS: -0.7 (2.5)% vs. -3.4 (2.3)%; ΔAFI: -0.8 (2.9)% vs. -3.6 (3.1)%, p layer-specific GLS values and AFI were statistically similar (p = 0.19). The four Δvalues provided independent predictive value to the risk assessment given by gender, age, wall motion and ΔEF (p = 0.002, AFI and p layer-specific GLS). The accuracies were acceptable (71-80%) with modest sensitivities (54-65%) and high specificities (80-91%). The deformation response to vasodilator infusion was associated with the presence of CAD. Endocardial, midventricular and epicardial GLS and AFI from adenosine SE had similar diagnostic values. The specificities were high, but the modest sensitivities are a limitation to the clinical application.

  4. Evaluation of missing pellet surface geometry on cladding stress distribution and magnitude

    Energy Technology Data Exchange (ETDEWEB)

    Capps, Nathan [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Montgomery, Robert [Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Sunderland, Dion [Pacific Northwest National Laboratory, Richland, WA 99354 (United States); ANATECH Corp, San Diego, CA 92121 (United States); Pytel, Martin [Electric Power Research Institute, Palo Alto, CA 94304 (United States); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2016-08-15

    Highlights: • Stress concentrations are related to pellet defect geometries. • The presence of radial cracks cause increases in stress concentration. • Increasing the size of MPS causes an increase hoop stress concentrations. - Abstract: Missing pellet surface (MPS) defects are local geometric defects in nuclear fuel pellets that result from pellet mishandling or manufacturing. The presence of MPS defects can cause significant clad stress concentrations that can lead to through-wall cladding failure for certain combinations of fuel burnup, and reactor power level or power change. Consequently, the impact of MPS defects has limited the rate of power increase, or ramp rate, in both pressurized and boiling water reactors (PWRs and BWRs, respectively). Improved three-dimensional (3-D) fuel performance models of MPS defect geometry can provide better understanding of the probability for pellet clad mechanical interaction (PCMI), and correspondingly the available margin against cladding failure by stress corrosion cracking (SCC). The Consortium of Advanced Simulations of Light Water Reactors (CASL) has been developing the Bison-CASL fuel performance code to consider the inherently multi-physics and multi-dimensional mechanisms that control fuel behavior, including cladding stress concentrations resulting from MPS defects. This paper evaluates the cladding hoop stress distributions as a function of MPS defect geometry with discrete pellet radial cracks for a set of typical operating conditions in a PWR fuel rod. The results provide a first step toward a probabilistic approach to assess cladding failure during power maneuvers. This analysis provides insight into how varying pellet defect geometries affect the distribution of the cladding stress, as well as the temperature distributions within the fuel and clad; and are used to develop stress concentration factors for comparing 2-D and 3-D models.

  5. A wafer mapping technique for residual stress in surface micromachined films

    Science.gov (United States)

    Schiavone, G.; Murray, J.; Smith, S.; Desmulliez, M. P. Y.; Mount, A. R.; Walton, A. J.

    2016-09-01

    The design of MEMS devices employing movable structures is crucially dependant on the mechanical behaviour of the deposited materials. It is therefore important to be able to fully characterize the micromachined films and predict with confidence the mechanical properties of patterned structures. This paper presents a characterization technique that enables the residual stress in MEMS films to be mapped at the wafer level by using microstructures released by surface micromachining. These dedicated MEMS test structures and the associated measurement techniques are used to extract localized information on the strain and Young’s modulus of the film under investigation. The residual stress is then determined by numerically coupling this data with a finite element analysis of the structure. This paper illustrates the measurement routine and demonstrates it with a case study using electrochemically deposited alloys of nickel and iron, particularly prone to develop high levels of residual stress. The results show that the technique enables wafer mapping of film non-uniformities and identifies wafer-to-wafer differences. A comparison between the results obtained from the mapping technique and conventional wafer bow measurements highlights the benefits of using a procedure tailored to films that are non-uniform, patterned and surface-micromachined, as opposed to simple standard stress extraction methods. The presented technique reveals detailed information that is generally unexplored when using conventional stress extraction methods such as wafer bow measurements.

  6. Ecological Screening Values for Surface Water, Sediment, and Soil: 2005 Update

    Energy Technology Data Exchange (ETDEWEB)

    Friday, G. P.

    2005-07-18

    One of the principal components of the environmental remediation program at the Savannah River Site (SRS) is the assessment of ecological risk. Used to support CERCLA, RCRA, and DOE orders, the ecological risk assessment (ERA) can identify environmental hazards and evaluate remedial action alternatives. Ecological risk assessment is also an essential means for achieving DOE's risk based end state vision for the disposition of nuclear material and waste hazards, the decommissioning of facilities, and the remediation of inactive waste units at SRS. The complexity of an ERA ranges from a screening level ERA (SLERA) to a full baseline ERA. A screening level ecological risk assessments, although abbreviated from a baseline risk assessment, is nonetheless considered a complete risk assessment (EPA, 2001a). One of the initial tasks of any ERA is to identify constituents that potentially or adversely affect the environment. Typically, this is accomplished by comparing a constituent's maximum concentration in surface water, sediment, or soil with an ecological screening value (ESV). The screening process can eliminate many constituents from further consideration in the risk assessment, but it also identifies those that require additional evaluation. This document is an update of a previous compilation (Friday, 1998) and provides a comprehensive listing of ecological screening values for surface water, sediment, and soil. It describes how the screening values were derived and recommends benchmarks that can be used for ecological risk assessment. The sources of these updated benchmarks include the U.S. Environmental Protection Agency (EPA), U.S. Fish and Wildlife Service (USFWS), U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), Oak Ridge National Laboratory (ORNL), the State of Florida, the Canadian Council of Ministers of the Environment (CCME), the Dutch Ministry of the Environment (RIVM), and the scientific literature. It

  7. Relationship between chemical shift value and accessible surface area for all amino acid atoms

    Directory of Open Access Journals (Sweden)

    Rieping Wolfgang

    2009-04-01

    Full Text Available Abstract Background Chemical shifts obtained from NMR experiments are an important tool in determining secondary, even tertiary, protein structure. The main repository for chemical shift data is the BioMagResBank, which provides NMR-STAR files with this type of information. However, it is not trivial to link this information to available coordinate data from the PDB for non-backbone atoms due to atom and chain naming differences, as well as sequence numbering changes. Results We here describe the analysis of a consistent set of chemical shift and coordinate data, in which we focus on the relationship between the per-atom solvent accessible surface area (ASA in the reported coordinates and their reported chemical shift value. The data is available online on http://www.ebi.ac.uk/pdbe/docs/NMR/shiftAnalysis/index.html. Conclusion Atoms with zero per-atom ASA have a significantly larger chemical shift dispersion and often have a different chemical shift distribution compared to those that are solvent accessible. With higher per-atom ASA, the chemical shift values also tend towards random coil values. The per-atom ASA, although not the determinant of the chemical shift, thus provides a way to directly correlate chemical shift information to the atomic coordinates.

  8. On the modelling of semi-insulating GaAs including surface tension and bulk stresses

    Energy Technology Data Exchange (ETDEWEB)

    Dreyer, W.; Duderstadt, F.

    2004-07-01

    Necessary heat treatment of single crystal semi-insulating Gallium Arsenide (GaAs), which is deployed in micro- and opto- electronic devices, generate undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid/solid interface and deviatoric stresses in the solid. The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law which gives an appropriate stress/strain relation for many solids in the small strain regime. We establish criteria, which allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law. The main objectives of this study are: (i) We develop a thermo-mechanical model that describes diffusion and interface motion, which both are strongly influenced by surface tension effects and deviatoric stresses. (ii) We give an overview and outlook on problems that can be posed and solved within the framework of the model. (iii) We calculate non-standard phase diagrams, i.e. those that take into account surface tension and non-deviatoric stresses, for GaAs above 786 C, and we compare the results with classical phase diagrams without these phenomena. (orig.)

  9. Ultimate pH values and bacteriological condition of meat and stress metabolites in blood of transported reindeer bulls

    Directory of Open Access Journals (Sweden)

    E. Wiklund

    2001-03-01

    Full Text Available Twenty-three reindeer bulls, aged 2-3 years, fed during two winter months at the Vuolda reindeer research station in Arjeplog, Sweden, were used in the study. The first group of eight reindeer was moved from their feeding corral to a selection corral, captured by lasso and stunned with a captive bolt outside the selection corral. The second group of seven reindeer was moved to the selection corral, captured by lasso and restrained, after which they were loaded onto a lorry- and transported for 1 hour and then slaughtered. The third group of eight reindeer was moved to the selection corral and herded directly onto the lorry, without any manual handling. They were transported for 5 h and then slaughtered. In both transport groups, four reindeer were fitted with pre-programmed automatic blood sampling equipment (ABSE. ABSE sampled blood at predetermined times via a jugular vein catheter. Ultimate pH-values in three muscles (Mm. longissimus, triceps brachii and biceps femoris were significantly lower in the group carefully handled and transported for 5 h compared with the other two groups. The physiological mechanisms behind these results are discussed. Samples from M. semimembranosus were collected at slaughter and after 2, 6 and 10 days of refrigerated storage (+4 °C. The samples were analysed for total counts of aerobic bacteria (pour-plated in Tryptone Glucose Extract Agar, Difco, incubated at 20 °C and 30 °C, respectively for 72 h, coliform bacteria 37 °C (pour-plated in Violet Red Bile Agar, Oxoid, incubated at 37 °C for 24 h, Enterococci (surface-plated onto Slantez and Bartley Agar, Oxoid, incubated at 44 °C for 48 h and Bacillus cereus (surface-plated onto Blood Agar Plates (Blood Agar Base, Difco, supplemented with 5% defibrinated horse blood 30 °C for 24 h. All samples fell in the range 'fit for consumption'. At slaughter, there was no difference in ASAT activity, urea and Cortisol concentrations between the two transported groups

  10. Prognostic value of normal stress-only myocardial perfusion imaging: a comparison between conventional and CZT-based SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, Shu; Ottervanger, Jan Paul; Timmer, Jorik R. [Isala Hospital, Department of Cardiology, Zwolle (Netherlands); Mouden, Mohamed; Engbers, Elsemiek [Isala Hospital, Department of Cardiology, Zwolle (Netherlands); Isala Hospital, Department of Nuclear Medicine, Zwolle (Netherlands); Knollema, Siert; Jager, Pieter L. [Isala Hospital, Department of Nuclear Medicine, Zwolle (Netherlands)

    2016-02-15

    Single photon emission computed tomography (SPECT) myocardial perfusion imaging has proven to have prognostic importance in patients with suspected stable coronary artery disease (CAD). The recently introduced ultrafast cadmium zinc telluride (CZT)-based gamma cameras have been associated with less equivocal findings and more normal interpretations, allowing stress-only imaging to be performed more often. However, it is yet unclear whether normal stress-only CZT SPECT has comparable prognostic value as normally interpreted stress-only conventional SPECT. The study population consisted of 1,650 consecutive patients without known CAD with normal stress-only myocardial perfusion results with either conventional (n = 362) or CZT SPECT (n = 1,288). The incidence of major adverse cardiac events (MACE, all-cause death, non-fatal myocardial infarction and/or coronary revascularization) was compared between the conventional SPECT and CZT SPECT groups. Multivariable analyses using the Cox model were used to adjust for differences in baseline variables. Patients scanned with CZT were less often male (33 vs 39 %), had less often hypercholesterolaemia (41 vs 50 %) and had more often a family history of CAD (57 vs 49 %). At a median follow-up time of 37 months (interquartile range 28-45 months) MACE occurred in 68 patients. The incidence of MACE was 1.5 %/year in the CZT group, compared to 2.0 %/year in the conventional group (p = 0.08). After multivariate analyses, there was a trend to a lower incidence of MACE in the CZT SPECT group (hazard ratio 0.61, 95 % confidence interval 0.35-1.04, p = 0.07). The prognostic value of normal stress-only CZT SPECT is at least comparable and may be even better than that of normal conventional stress SPECT. (orig.)

  11. Traditional versus modern values, self-perceived interpersonal factors, and posttraumatic stress in Chinese and German crime victims.

    Science.gov (United States)

    Maercker, Andreas; Mohiyeddini, Changiz; Müller, Mario; Xie, Wei; Hui Yang, Zhi; Wang, Jiangping; Müller, Julia

    2009-06-01

    The influence of cultural factors on mental health is not disputed in general - but elaborated research approaches are still lacking. We investigate cultural influences not only by nationality but also by value orientation (modern vs. traditional). A cross-cultural comparison with Chinese and German crime victims included an assessment of value orientation according to Schwartz's theory (Schwartz, 1994) of personal values. Chinese and German adult crime victims were assessed. By means of structural equation multi-sample analysis, data of the two groups were compared. Traditional (conformity, benevolence, customs orientation) and modern values (achievement, hedonism, stimulation), traumatic exposure, posttraumatic stress (PTS), and two self-perceived interpersonal mediator processes (disclosure intentions, social acknowledgement as a victim) were assessed by self-report measures in 130 Chinese and 151 German crime victims. The two patterns of prediction for PTS differed between the countries: In the German sample both value types but in the Chinese sample only traditional values were directly or indirectly predictive of PTS. Traditional values inhibited social acknowledgement as a victim in China and Germany. In Germany, traditional values were related to increased PTS severity. Modern values predicted social acknowledgement as well as lower symptoms in Germany, but not in China. The study shows cultural and interpersonal factors that may contribute to the development of PTSD that are under-researched in contemporary psychology and psychotherapy.

  12. A 1-D Analytical Model for the Thermally Induced Stresses in the Mould Surface During Die Casting

    DEFF Research Database (Denmark)

    Hattel, Jesper; Hansen, Preben

    1994-01-01

    This paper presents an anlytically based method for predicting the normal stresses in a die mold surface exposed to a thermal load. A example of application of the method is the high-pressure di casting process where the surface stresses in critical cases lead to cracks. Expressions for the normal...

  13. Clinical utility and prognostic value of appropriateness criteria in stress echocardiography for the evaluation of valvular heart disease.

    Science.gov (United States)

    Bhattacharyya, Sanjeev; Kamperidis, Vasilis; Shah, Benoy Nalin; Roussin, Isabelle; Chahal, Navtej; Li, Wei; Khattar, Rajdeep; Senior, Roxy

    2013-09-01

    We examined the prognostic value of stress echocardiography appropriateness criteria for evaluation of valvular heart disease in 100 consecutive patients. Of the studies, 49%, 36%, and 15% were classified as appropriate, uncertain, and inappropriate, respectively. Over a median of 12.6 months, 24 events (12 deaths and 12 heart failure admissions) occurred. The 12-month event-free survival was significantly reduced in patients with appropriate or uncertain studies compared with patients with inappropriate studies (p = 0.04 and p = 0.005, respectively). There was no survival difference between patients with an appropriate or uncertain indication (p = 0.1). The only independent predictors of events were a positive stress echocardiogram (hazard ratio: 15.5, p valvular heart disease provide the ability to differentiate between patients at high- (appropriate group) and low- (inappropriate group) risk of cardiac events. Reclassification of the uncertain group may improve the differential value of these criteria.

  14. Academic stress and positive affect: Asian value and self-worth contingency as moderators among Chinese international students.

    Science.gov (United States)

    Liao, Kelly Yu-Hsin; Wei, Meifen

    2014-01-01

    The theoretical model proposed by Berry and colleagues (Berry, 1997; Berry, Kim, Minde, & Mok, 1987) highlights the importance of identifying moderators in the acculturation process. Accordingly, the current study examined the Asian cultural value of family recognition through achievement (FRTA) and contingency of self-worth on academic competence (CSW-AC) as moderators in the association between academic stress and positive affect among Chinese international students. A total of 370 Chinese international students completed online surveys. Results from a hierarchical regression indicated that while academic stress was negatively associated with positive affect, FRTA was positively associated with positive affect. In other words, those with high academic stress reported a lower level of positive affect. However, individuals who endorsed high levels of FRTA reported a higher level of positive affect. In addition, results also revealed a significant interaction between academic stress and CSW-AC on positive affect. Thus, the study's finding supported the moderator role of CSW-AC. Simple effect analyses were conducted to examine the significant interaction. The results showed that higher levels of CSW-AC strengthened the negative association between academic stress and positive affect but lower levels of CSW-AC did not. Future research directions and implications are discussed.

  15. The Effect of Heterogeneous Lithospheric Structure on Surface Stress and Tectonics on Mercury

    Science.gov (United States)

    Rosenburg, M. A.; Williams, J.; Aharonson, O.

    2008-12-01

    Observations of Mercury's surface from the Mariner 10 and MESSENGER spacecraft reveal a planet-wide distribution of lobate scarps, which are interpreted to be the surface expression of thrust faults due to global contraction. Statistical analysis of scarps mapped in images from both missions suggests that the orientations of these features are not consistent with a uniform distribution, the expected outcome for a contracting lithosphere of constant thickness. One possible explanation for this observation considers Mercury's thermal state, which is driven by the insolation pattern. Mercury's 3:2 spin-orbit resonance, in concert with its substantial orbital eccentricity of e = 0.20, causes long-wavelength surface temperature variations of more than 130 K. Corresponding variations in lithospheric thickness are hence expected. If the contraction occurred while Mercury was in this dynamical state, the resulting stress distribution recorded on the surface during global cooling and inner core solidification may reflect this heterogeneity. We seek to determine whether contraction of a lithosphere with lateral thickness variations can explain the observed lobate scarp orientations on Mercury's surface. We employ the three-dimensional, viscoelastic, finite element model CitcomSVE along with a thermal evolution model to study Mercury's response to cooling, inner core formation, and lithosphere growth and to track the accumulation of stress in the lithosphere. The resulting stress pattern can then be compared to the orientations and distribution of scarps mapped on the surface of Mercury. Preliminary results indicate systematic variations between the expected orientation of faults in the "cold poles," where the lithosphere is thicker and the "hot poles," where the lithosphere is weaker. As MESSENGER returns more data, comparisons between model results and surface features will be refined.

  16. Surface Wind Stresses and Triggering of Global Dust Storms on Mars

    Science.gov (United States)

    Mischna, Michael A.; Shirley, James H.

    2016-10-01

    Global dust storms on Mars occur during summer in the southern hemisphere, but their occurrence in some years and not in others has stubbornly eluded explanation. Shirley (2016, in review, and at arxiv.org/abs/1605.02707) and Mischna and Shirley (2016, in revision, and at arxiv.org/abs/1602.09137) have demonstrated the role of a so-called "coupling term acceleration" (CTA) in modifying the Mars global circulation through potential exchange of Mars' orbital and rotational momenta. The CTA has been incorporated into the MarsWRF general circulation model (GCM), which reveals distinct changes to the circulation due to the CTA, leading to conditions favorable to GDS formation in all years in which perihelion season GDS were observed, and conditions unfavorable in nearly all other years. These circulation changes reveal themselves, in part, through changes in surface wind stress, which is a strong function of near-surface wind speed. We present additional analysis of these results for the past years with perihelion season GDS (7 in total) showing commonalities in the evolution of surface stresses in the season leading up to GDS initiation. Specifically, the enhancement of surface stress during this pre-storm season, arising from the orbit-spin coupling in years with perihelion season storms, presents some common patterns. Among these are the rate and duration of increase of wind stress, and the minimum level of enhancement from the CTA that is apparently required in these years prior to initiation of a GDS. Previously we assessed changes in surface stress using a simple, dust-free model atmosphere. Here, further, we perform parallel simulations for MY 24-27 using realistic dust profiles from TES limb observations. The inclusion of dust in the GCM modifies atmospheric opacity and will alter global atmospheric temperatures leading to a markedly different atmospheric state. We find that the inclusion of dust in the atmosphere reduces the magnitude of surface stresses as

  17. Effect of Laser Shock Peening on surface properties and residual stress of Al6061-T6

    Science.gov (United States)

    Salimianrizi, A.; Foroozmehr, E.; Badrossamay, M.; Farrokhpour, H.

    2016-02-01

    The purpose of this study is to investigate the effects of Laser Shock Peening (LSP) on Al 6061-T6. The confined LSP regime using Nd: YAG laser with 1200 mJ of energy per pulse and 8 ns of pulse width were applied. The treated specimens were evaluated by means of surface integrity with optical microscopy, scanning electron microscope, microhardness, surface roughness and induced residual stress using an X-ray diffraction method. Results showed that by the use of LSP, compressive residual stress could effectively be induced on the surface of treated material. It was also revealed that the hardened depth of the material, up to a maximum depth of 1875 μm, could be achieved due to work hardening and grain refinement. In addition, surface roughness measurements showed that the LSP could deteriorate surface quality depending on the LSP parameters. The influences of beam overlap rates, number of laser shots and scanning pattern on microhardness as well as surface roughness are discussed.

  18. Residual stresses in a surface remelting of castings made of cobalt alloy MAR-M509 with a plasma generated in electric arc

    Directory of Open Access Journals (Sweden)

    Z. Opiekun

    2010-01-01

    Full Text Available The manuscript presents the results of measurements of residual stresses (RS in partial meltings of casting surfaces made of cobalt alloy MAR-M509. The partial meltings were made with an argon plasma beam by GTAW method. The values of RS were deter-mined by X-ray diffraction method in grazing incident geometry, by g-sin2ψ method and in Bragg-Brentano (BB geometry. It has been stated that RS values depend on the parameters of partial melting process. It has been claimed that compressive stresses, which are present in the thin layer up to ca 2 μm, convert to tensile stresses in deeper layers of partial meltings.

  19. The role of cold work and applied stress on surface oxidation of 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lozano-Perez, Sergio, E-mail: sergio.lozano-perez@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Rd., Oxford OX1 3PH (United Kingdom); Kruska, Karen [Department of Materials, University of Oxford, Parks Rd., Oxford OX1 3PH (United Kingdom); Iyengar, Ilya [Winchester College, College Street, Winchester SO23 9LX (United Kingdom); Terachi, Takumi; Yamada, Takuyo [Institute of Nuclear Safety System (INSS), 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer FIB 3D sequential sectioning is an ideal technique to characterize surface oxidation. Black-Right-Pointing-Pointer 3D models of the oxide can be produced with nanometre resolution. Black-Right-Pointing-Pointer The effects of stress and cold work in grain boundary oxidation have been analysed. Black-Right-Pointing-Pointer At least three different oxidation modes are observed when stress is applied. - Abstract: FIB 3-dimensional (3D) sequential sectioning has been used to characterize environmental degradation of 304 stainless steels in pressurized water reactor (PWR) simulated primary water. In particular, the effects of cold work and applied stress on oxidation have been studied in detail. It was found that a description of the oxidation behaviour of this alloy is only complete if it is treated statistically, since it can suffer from high variability depending on the feature described.

  20. Joint spatiotemporal variability of global sea surface temperatures and global Palmer drought severity index values

    Science.gov (United States)

    Apipattanavis, S.; McCabe, G.J.; Rajagopalan, B.; Gangopadhyay, S.

    2009-01-01

    Dominant modes of individual and joint variability in global sea surface temperatures (SST) and global Palmer drought severity index (PDSI) values for the twentieth century are identified through a multivariate frequency domain singular value decomposition. This analysis indicates that a secular trend and variability related to the El Niño–Southern Oscillation (ENSO) are the dominant modes of variance shared among the global datasets. For the SST data the secular trend corresponds to a positive trend in Indian Ocean and South Atlantic SSTs, and a negative trend in North Pacific and North Atlantic SSTs. The ENSO reconstruction shows a strong signal in the tropical Pacific, North Pacific, and Indian Ocean regions. For the PDSI data, the secular trend reconstruction shows high amplitudes over central Africa including the Sahel, whereas the regions with strong ENSO amplitudes in PDSI are the southwestern and northwestern United States, South Africa, northeastern Brazil, central Africa, the Indian subcontinent, and Australia. An additional significant frequency, multidecadal variability, is identified for the Northern Hemisphere. This multidecadal frequency appears to be related to the Atlantic multidecadal oscillation (AMO). The multidecadal frequency is statistically significant in the Northern Hemisphere SST data, but is statistically nonsignificant in the PDSI data.

  1. Regression analysis in modeling of air surface temperature and factors affecting its value in Peninsular Malaysia

    Science.gov (United States)

    Rajab, Jasim Mohammed; Jafri, Mohd. Zubir Mat; Lim, Hwee San; Abdullah, Khiruddin

    2012-10-01

    This study encompasses air surface temperature (AST) modeling in the lower atmosphere. Data of four atmosphere pollutant gases (CO, O3, CH4, and H2O) dataset, retrieved from the National Aeronautics and Space Administration Atmospheric Infrared Sounder (AIRS), from 2003 to 2008 was employed to develop a model to predict AST value in the Malaysian peninsula using the multiple regression method. For the entire period, the pollutants were highly correlated (R=0.821) with predicted AST. Comparisons among five stations in 2009 showed close agreement between the predicted AST and the observed AST from AIRS, especially in the southwest monsoon (SWM) season, within 1.3 K, and for in situ data, within 1 to 2 K. The validation results of AST with AST from AIRS showed high correlation coefficient (R=0.845 to 0.918), indicating the model's efficiency and accuracy. Statistical analysis in terms of β showed that H2O (0.565 to 1.746) tended to contribute significantly to high AST values during the northeast monsoon season. Generally, these results clearly indicate the advantage of using the satellite AIRS data and a correlation analysis study to investigate the impact of atmospheric greenhouse gases on AST over the Malaysian peninsula. A model was developed that is capable of retrieving the Malaysian peninsulan AST in all weather conditions, with total uncertainties ranging between 1 and 2 K.

  2. Seed set, pollen morphology and pollen surface composition response to heat stress in field pea.

    Science.gov (United States)

    Jiang, Yunfei; Lahlali, Rachid; Karunakaran, Chithra; Kumar, Saroj; Davis, Arthur R; Bueckert, Rosalind A

    2015-11-01

    Pea (Pisum sativum L.) is a major legume crop grown in a semi-arid climate in Western Canada, where heat stress affects pollination, seed set and yield. Seed set and pod growth characteristics, along with in vitro percentage pollen germination, pollen tube growth and pollen surface composition, were measured in two pea cultivars (CDC Golden and CDC Sage) subjected to five maximum temperature regimes ranging from 24 to 36 °C. Heat stress reduced percentage pollen germination, pollen tube length, pod length, seed number per pod, and the seed-ovule ratio. Percentage pollen germination of CDC Sage was greater than CDC Golden at 36 °C. No visible morphological differences in pollen grains or the pollen surface were observed between the heat and control-treated pea. However, pollen wall (intine) thickness increased due to heat stress. Mid-infrared attenuated total reflectance (MIR-ATR) spectra revealed that the chemical composition (lipid, proteins and carbohydrates) of each cultivar's pollen grains responded differently to heat stress. The lipid region of the pollen coat and exine of CDC Sage was more stable compared with CDC Golden at 36 °C. Secondary derivatives of ATR spectra indicated the presence of two lipid types, with different amounts present in pollen grains from each cultivar.

  3. Experimental Determination of Surface Stress Changes in Electrochemical Systems – Possibilities and Pitfalls

    OpenAIRE

    G. G. Láng; Sas, N. S.; Vesztergom, S.

    2009-01-01

    In the present paper, the different techniques used for the determination of changes of surface stress of solid electrodes, as well as the kind and quality of information that can be achieved using these methods are discussed. The most important methods are briefly reviewed and advantages/drawbacks highlighted. Special attention is paid to issues related to the use of the “bending beam” (“bending cantilever”, “laser beam deflection”, “wafer curvature”, etc.) methods. Recent dev...

  4. Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materials

    Science.gov (United States)

    1988-09-15

    the strength and fatigue characteristics of ZBLAN (zirconium barium-lanthanum-aluminum-sodium fluoride) optical glass fiber obtained from British...Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materlals 12. PERSONAL AUTHOR(S) Carlo G. Pantano 13a. TYPE OF...fluorozirconate glasses . °. DTICS ELEC T E DEC 09 I 20. DISTRIBUTION/ AVAILABILITY OF ABSTRACT 21.-A% RACT SECURITY CLASSIFICATION [BUNCLASSIFIED/UNLIMITED

  5. Interfacial stress balances in structured continua and free surface flows in ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, Arlex [School of Chemical Engineering, Universidad Industrial de Santander, Calle 9 Cra. 27, Edificio 24, Bucaramanga, Santander (Colombia); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611, USA and Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-04-15

    Interfacial linear and internal angular momentum balances are obtained for a structured continuum and for the special case of a ferrofluid, a suspension of magnetic nanoparticles in a Newtonian fluid. The interfacial balance equations account for the effects of surface tension and surface tension gradient, magnetic surface excess forces, antisymmetric stresses, and couple stresses in driving interfacial flows in ferrofluids. Application of the interfacial balance equations is illustrated by obtaining analytical expressions for the translational and spin velocity profiles in a thin film of ferrofluid on an infinite flat plate when a rotating magnetic field is applied with axis of rotation parallel to the ferrofluid/air interface. The cases of zero and non-zero spin viscosity are considered for small applied magnetic field amplitude. Expressions for the maximum translational velocity, slope of the translational velocity profile at the ferrofluid/air interface, and volumetric flow rate are obtained and their use to test the relevance of spin viscosity and couple stresses in the flow situation under consideration is discussed.

  6. Prognostic value of fatty acid imaging in patients with angina pectoris without prior myocardial infarction: comparison with stress thallium imaging

    Energy Technology Data Exchange (ETDEWEB)

    Matsuki, Takayuki; Doi, Atsushi; Takahashi, Hiroshi; Iwata, Michihiro; Sakamoto, Takashi; Yamauchi, Kazuaki; Shimazaki, Masaru [Shin-Nittetsu Muroran General Hospital, Department of Cardiology, Muroran (Japan); Tamaki, Nagara; Morita, Koichi [Hokkaido University Graduate School of Medicine, Department of Nuclear Medicine, Sapporo (Japan); Nakata, Tomoaki; Shimamoto, Kazuaki [Sapporo Medical University, Second Department of Internal Medicine, School of Medicine, Sapporo (Japan)

    2004-12-01

    A fatty acid analogue, {sup 123}I-labelled {beta}-methyl iodophenyl pentadecanoic acid (BMIPP), has been used to identify ischaemic and metabolically impaired myocardium. However, the prognostic value of BMIPP imaging, particularly in relation to stress myocardial perfusion imaging, remains unclear. Data from 167 consecutive patients with angina pectoris but without prior myocardial infarction (MI) who had undergone both BMIPP and stress {sup 201}Tl (sTL) imaging were analysed. Tracer uptake was graded using a 13-segment, 4-point scoring model. Patients were followed up for 48 months with primary end points (cardiac death, non-fatal MI) as hard cardiac events and with secondary end points (late revascularisation, recurrent angina and heart failure) as soft events. For overall cardiac events (5 hard and 29 soft events), Kaplan-Meier analysis revealed significantly lower event rates in subgroups with normal BMIPP uptake, a summed difference score of sTL (SDS) of <3 or absence of diabetes mellitus when compared to each counterpart. Multivariate Cox's analysis revealed reduced BMIPP uptake, SDS {>=}3, diabetes and reduced ejection fraction to be significant predictors. Negative predictive values of normal BMIPP and SDS <3 for all events were 91% and 84%, respectively. No hard event occurred in 66 patients with normal BMIPP uptake, whereas two patients with SDS <3 but impaired BMIPP uptake had hard events. In conclusion, normal BMIPP imaging is an excellent prognostic sign, independently of stress myocardial perfusion imaging, in patients with angina pectoris without prior MI. (orig.)

  7. Residual compressive surface stress increases the bending strength of dental zirconia.

    Science.gov (United States)

    Inokoshi, Masanao; Zhang, Fei; Vanmeensel, Kim; De Munck, Jan; Minakuchi, Shunsuke; Naert, Ignace; Vleugels, Jozef; Van Meerbeek, Bart

    2017-04-01

    To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades. Fully-sintered zirconia specimens (4.0×3.0×45.0mm(3)) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al2O3 zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND+HEAT': (1) followed by annealing at 1100°C for 30min; (3) 'GROUND+Al2O3 SANDBLASTED': (1) followed by sandblasting using Al2O3; (4) 'GROUND+CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine. Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength. Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Functional value of elytra under various stresses in the red flour beetle, Tribolium castaneum

    Science.gov (United States)

    Linz, David M.; Hu, Alan W.; Sitvarin, Michael I.; Tomoyasu, Yoshinori

    2016-01-01

    Coleoptera (beetles) is a massively successful order of insects, distinguished by their evolutionarily modified forewings called elytra. These structures are often presumed to have been a major driving force for the successful radiation of this taxon, by providing beetles with protection against a variety of harsh environmental factors. However, few studies have directly demonstrated the functional significance of the elytra against diverse environmental challenges. Here, we sought to empirically test the function of the elytra using Tribolium castaneum (the red flour beetle) as a model. We tested four categories of stress on the beetles: physical damage to hindwings, predation, desiccation, and cold shock. We found that, in all categories, the presence of elytra conferred a significant advantage compared to those beetles with their elytra experimentally removed. This work provides compelling quantitative evidence supporting the importance of beetle forewings in tolerating a variety of environmental stresses, and gives insight into how the evolution of elytra have facilitated the remarkable success of beetle radiation. PMID:27708390

  9. Value added phytoremediation of metal stressed soils using phosphate solubilizing microbial consortium.

    Science.gov (United States)

    Gupta, Pratishtha; Kumar, Vipin

    2017-01-01

    The presence of heavy metals in the soil is a matter of growing concern due to their toxic and non-biodegradable nature. Lack of effectiveness of various conventional methods due to economic and technical constraints resulted in the search for an eco-friendly and cost-effective biological techniques for heavy metal removal from the environment. Until now, phytoremediation has emerged as an innovative technique to address the problem. However, the efficiency of phytoremediation process is hindered under the high metal concentration conditions. Hence, phosphate solubilizing microbes (PSM) assisted phytoremediation technique is gaining more insight as it can reduce the contamination load even under elevated metal stressed conditions. These microbes convert heavy metals into soluble and bioavailable forms, which consequently facilitate phytoremediation. Several studies have reported that the use of microbial consortium for remediation is considered more effective as compared to single strain pure culture. Therefore, this review paper focuses on the current trends in research related to PSM mediated uptake of heavy metal by plants. The efficiency of PSM consortia in enhancing the phytoremediation process has also been reviewed. Moreover, the role of phosphatase enzymes in the mineralization of organic forms of phosphate in soil is further discussed. Biosurfactant mediated bioremediation of metal polluted soils is a matter of extensive research nowadays. Hence, the recent advancement of using biosurfactants in enhanced phytoremediation of metal stressed soils is also described.

  10. Microalgae for high-value compounds and biofuels production: a review with focus on cultivation under stress conditions.

    Science.gov (United States)

    Markou, Giorgos; Nerantzis, Elias

    2013-12-01

    Microalgal biomass as feedstock for biofuel production is an attracting alternative to terrestrial plant utilization for biofuels production. However, today the microalgal cultivation systems for energy production purposes seem not yet to be economically feasible. Microalgae, though cultivated under stress conditions, such as nutrient starvation, high salinity, high temperature etc. accumulate considerable amounts (up to 60-65% of dry weight) of lipids or carbohydrates along with several secondary metabolites. Especially some of the latter are valuable compounds with an enormous range of industrial applications. The simultaneous production of lipids or carbohydrates for biofuel production and of secondary metabolites in a biorefinery concept might allow the microalgal production to be economically feasible. This paper aims to provide a review on the available literature about the cultivation of microalgae for the accumulation of high-value compounds along with lipids or carbohydrates focusing on stress cultivation conditions. © 2013.

  11. NUMERICAL STUDY OF WAVE EFFECTS ON SURFACE WIND STRESS AND SURFACE MIXING LENGTH BY THREE-DIMENSIONAL CIRCULATION MODELING

    Institute of Scientific and Technical Information of China (English)

    LIANG Bing-chen; LI Hua-jun; LEE Dong-yong

    2006-01-01

    The effects of waves on Surface Drag Coefficient (SDC) and surface mixing length were analyzed and discussed by carrying out three-dimensional current modeling for the Bohai Sea in the present work. A three- dimensional coupled hydrodynamical-ecological model for regional and shelf seas (COHERENS) incorporating the influences of wave-current interactions was coupled with the third-generation wave model swan taking into account time-varying currents. The effects of waves on currents were included in the SDC, surface mixing length and bottom drag coefficient. Firstly, the formulations in Donelan were incorporated into the COHERENS to account for wave-dependent SDC. In order to compare simulation results for the wave-dependent SDC, the simulation for wind-dependent SDC was also carried out. Second, Wave-Induced Surface Mixing Length (described as WISML sometimes in this paper) was incorporated into the COHERENS. Four numerical experiments were conducted to discuss the effects of two kinds of wave processes. Generally, the values of time series of current velocity and water surface elevation given by the simulation with all of the three wave processes have a good agreement with observed data. The existence of WISML changes obviously current vertical profiles and the existence of the wave dependent SDC modifies the current field of both top and bottom layers with the wind-dependent SDC.

  12. [Effects of lead stress on net photosynthetic rate, SPAD value and ginsenoside production in Ginseng (Panax ginseng)].

    Science.gov (United States)

    Liang, Yao; Jiang, Xiao-Li; Yang, Fen-Tuan; Cao, Qing-Jun; Li, Gang

    2014-08-01

    The paper aimed to evaluate the effects of lead stress on photosynthetic performance and ginsenoside content in ginseng (Panax ginseng). To accomplish this, three years old ginseng were cultivated in pot and in phytotron with different concentrations of lead, ranging from 0 to 1000 mg x kg(-1) soil for a whole growth period (about 150 days). The photosynthetic parameters in leaves and ginsenoside content in roots of ginseng were determined in green fruit stage and before withering stage, respectively. In comparison with the control, net photosynthetic rate and SPAD value in ginseng leaves cultivated with 100 and 250 mg x kg(-1) of lead changed insignificantly, however, ginseng supplied with 500 and 1 000 mg x kg(-1) of lead showed a noticeably decline in the net rate of photosynthesis and SPAD value (P ginseng roots cultivated with 100 mg x kg(-1) of lead showed insignificantly change compared to the control, but the content increased remarkably in treatments supplied with 250, 500, 1 000 mg x kg(-1) of lead (P ginsengs exposed to 1000 mg x kg(-1) of lead. The net photosynthetic rate and SPAD value in leaves of ginseng both showed significantly negative linear correlations with lead stress level (P ginseng leaves, but benefits for accumulation of secondary metabolism (total content of ginsenoside) in ginseng root.

  13. Evaluation value of real-time three-dimensional adenosine stress echocardiography and coronary angiography for patients with stable angina pectoris

    Institute of Scientific and Technical Information of China (English)

    Ya-Li Wu; Nan-Jue Jiang; Yan Cai

    2016-01-01

    Objective:To study the evaluation value of real-time three-dimensional adenosine stress echocardiography and coronary angiography for patients with stable angina pectoris. Methods:A total of 45 patients diagnosed with stable angina pectoris in our hospital between May 2014 and December 2015 were selected as the stable angina pectoris group (SAP group) of the study and 50 healthy subjects receiving physical examination in our hospital during the same period were selected as control group. Real-time three-dimensional adenosine stress echocardiography was performed to measure coronary flow reserve (CFR), serum was collected to determine lipid metabolism indexes and inflammation indexes, and peripheral blood mononuclear cells were collected to determine the expression levels of inflammatory regulatory molecules.Results:CFR of SAP group was significantly lower than that of control group and the more the number of coronary lesions, the lower the CFR of SAP group; serum Lp(a), LDL-C, ApoB, MIF-1α, ICAM-1, VCAM-1, CD40 and CD40L content as well as the fluorescence intensity of peripheral blood mononuclear cell surface TLR4 and NF-κB of SAP group were significantly higher than those of control group and negatively correlated with CFR level while serum HDL-C and ApoA1 content as well as the fluorescence intensity of peripheral blood mononuclear cell surface TIPE2 and BACH2 were significantly lower than those of control group and positively correlated with CFR level.Conclusion:CFR measured by real-time three-dimensional adenosine stress echocardiography significantly reduces in patients with stable angina pectoris and is correlated with lipid metabolism state and the degree of inflammation.

  14. Predictive value of urodynamics on outcome after midurethral sling surgery for female stress urinary incontinence

    NARCIS (Netherlands)

    Houwert, R. Marijn; Venema, Pieter L.; Aquarius, Annelies E.; Bruinse, Hein W.; Kil, Paul J. M.; Vervest, Harry A. M.

    2009-01-01

    OBJECTIVE: The aim of this study was to evaluate the value of urodynamic investigation in the preoperative workup of midurethral sling surgery and to identify risk factors for failure after 3 different midurethral sling procedures. STUDY DESIGN: Retrospective cohort study. 437 women who underwent a

  15. Residual stress and electromagnetic characteristics in loop type frequency selective surface embedded hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Mi; Seo, Yun Seok; Chun, Heoung Jae [Yonsei University, Seoul (Korea, Republic of); Hong, Ik Pyo [Kongju National University, Cheonan (Korea, Republic of); Park, Yong Bae [Ajoo University, Suwon (Korea, Republic of); Kim, Yoon Jae [Agency for defense development, Daejeon (Korea, Republic of)

    2015-01-15

    Residual stresses occur in frequency-selective surface (FSS)-embedded composite structures after co-curing due to differences between the coefficients of thermal expansion between composite skins and FSSs. Furthermore, the electromagnetic characteristics may be affected by the deformation of the FSS pattern by residual stresses. Therefore, we studied the changes in electromagnetic characteristics due to the deformation of FSS, using residual stresses to deform loop-type FSS-embedded hybrid composites. We considered the effects of loop-type FSS patterns of equal dimension as well as the stacking sequences of composite laminates on the electromagnetic characteristics of FSSs: Square loop, triangular loop and circular loop. The stacking sequences of composite laminates considered in this study were [0]{sub 8}, [0/90]{sub 4}, [+-45]{sub 4} and [0/+-45/90]{sub 2}. The FSS was located between composite laminates in the middle plane. To determine the residual stresses and deformations in the FSS embedded laminate structures, the thermal loading condition in the finite element analysis was induced by cooling the hybrid structures from 125 .deg. C to 20 .deg. C based on the cure cycle of the composite. Also, the electromagnetic reflection characteristics of the hybrid structures were predicted using deformed models by residual stresses, considering the effects of stacking sequence of composite laminates. The results showed that the maximum residual stresses and deformations were produced in the [0]{sub 8} composites with all three loop-types of FSS pattern. However, the maximum resonance frequency shifts occurred in the square and triangle loop-types with stacking sequence of [0]{sub 8} , while the maximum resonance frequency shift occurred in the circular loop-type with stacking sequence of [0/+-45/90]{sub 2}.

  16. Evaluation of Stress Intensity Factors for Multiple Cracked Circular Disks Under Crack Surface Tractions with SBFEM

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-yu; LIN Gao; LI Xiao-chuan; XU Feng-lin

    2013-01-01

    Stress intensity factors (SIFs) for the cracked circular disks under different distributing surface tractions are evaluated with the scaled boundary finite element method (SBFEM).In the SBFEM,the analytical advantage of the solution in the radial direction allows SIFs to be directly determined from its definition,therefore no special crack-tip treatment is necessary.Furthermore anisotropic material behavior can be treated easily.Different distributions of surface tractions are considered for the center and double-edge-cracked disks.The benchmark examples are modeled and an excellent agreement between the results in the present study and those in published literature is found.It shows that SBFEM is effective and possesses high accuracy.The SIFs of the cracked orthotropic material circular disks subjected to different surface tractions are also evaluated.The technique of substructure is applied to handle the multiple cracks problem.

  17. Effects of Surface State and Applied Stress on Stress Corrosion Cracking of Alloy 690TT in Lead-containing Caustic Solution

    Institute of Scientific and Technical Information of China (English)

    Zhiming Zhang; Jianqiu Wang; En-Hou Han; Wei Ke

    2012-01-01

    The effects of surface state and applied stress on the stress corrosion cracking (SCC) behaviors of thermally treated (TT) Alloy 690 in 10 wt% NaOH solution with 100 mg/L litharge at 330 ℃ were investigated using C-ring samples with four kinds of surface states and two different stress levels. Sample outer surfaces of the first three kinds were ground to 400 grit (ground), shot-peened (SP) and electro-polished (EP) and the last one was used as the as-received state. Two samples of every kind were stressed to 100% and 200% yield stress of Alloy 690TT, respectively. The results showed that the oxide film consisted of three layers whereas continuous layer rich in Cr was not found. The poor adhesive ability indicated that the oxide film could not protect the matrix from further corrosion. Lead was found in the oxide film and the oxides at the crack paths and accelerated the dissolution of thermodynamically unstable Cr in these locations and also in the matrix. The crack initiation and propagation on Alloy 690TT were effectively retarded by SP and EP treatments but were enhanced by grinding treatment, compared with the cracks on the as-received surface. The cracking severity was also enhanced by increasing the externally applied stress. The accelerated dissolution of Cr and the local tensile stress concentration in the near-surface layer caused by cold-working and higher applied stress reduced the SCC-resistance of Alloy 690TT in the studied solution.

  18. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    Science.gov (United States)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  19. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.

    1997-08-01

    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  20. Mapping b-value for 2009 Harrat Lunayyir earthquake swarm, western Saudi Arabia and Coulomb stress for its mainshock

    Science.gov (United States)

    Abdelfattah, Ali K.; Mogren, Saad; Mukhopadhyay, Manoj

    2017-01-01

    The Harrat Lunayyir (HL) earthquake swarm of 2009 originated in the HL volcanic field and attracted global attention mainly due to three factors: (i) its relatively short life span that ushered a large frequency of the swarm population (30,000 events in swarm epicenter zone was contained within a small crustal volume under the HL and (iii) the migratory nature of the swarm following the tectonic trend of a normal fault zone beneath HL. The HL belongs to the Large Igneous Province of Saudi Arabia (LIP-SA) where it correlates to the Great Dikes locally. Our aim in this study is to describe the spatial distribution of the hypocenters, b-value character, and Coulomb stress failure (CSF) in an attempt to analyze the underlying geodynamic process that caused the swarm. We utilize the relocated hypocenters monitored by local networks to examine the b-value characteristics for the swarm. This is best represented in a cross section showing two domains of higher b-value anomalies: two patches occurring at shallow depth and at the deeper crust to the SE from the mainshock originated at the shallower depth northwestward. Consistently positive ΔCFF pattern with a large percentage of aftershocks imply how the mainshock rupture controlled the aftershocks activity. This implies that the failure along the NNW fault trend is due to the prevailing ambient stress field imparted to the swarm. We model this by CSF associated with the mainshock for three time dependent situations: (a) foreshock and aftershock epicenters, (b) foreshock hypocenters, and (c) aftershock hypocenters. In actuality, multiple factors might have controlled the aftershock activity as we speculate that positive Coulomb stress was associated in an area where the higher b-value prevails. The CSF produced by the mainshock illustrates how the stress dissipated along the NNW normal fault zone that interrupts the Great Dykes along the Red Sea coast. These results further suggest that the crustal heterogeneity under HL

  1. RESEARCH OF VALUE OF DEFORMATION, STRESS AND SELF FREQUENCY OSCILLATION OF THE STAR SENSOR WITH EQUIVALENT INERTIAL WEIGHTING

    Directory of Open Access Journals (Sweden)

    R. V. Feodortsau

    2011-01-01

    Full Text Available The 3D-model of the star sensor was design in the Pro/ENGINEER program. Mechanical analysis of rigidity of the construction was carry out in MSC Patran program. The value of the deformation and equivalent stress by gravitation 1g and 30g for loading by axis X, Y, was carry out. Account of self frequency in range of 200 to 6000 Hz was compute, and for the first 10 modes were received shapes of oscillation of the device. 

  2. Evaluation of Missing Pellet Surface Geometry on Cladding Stress Distribution and Magnitude

    Energy Technology Data Exchange (ETDEWEB)

    Capps, Nathan A.; Montgomery, Robert O.; Sunderland, Dion J.; Spencer, Ben; Pytel, Martin; Wirth, Brian D.

    2014-10-01

    Missing pellet surface (MPS) defects are local geometric defects that periodically occur in nuclear fuel pellets, usually as a result of the mishandling during the manufacturing process. The presences of these defects can lead to clad stress concentrations that are substantial enough to cause a through wall failure for certain conditions of power level, burnup, and power increase. Consequently, the impact of potential MPS defects has limited the rate of power increase or ramp rates in both PWR and BWR systems. Improved 3D MPS models that consider the effect of the MPS geometry can provide better understanding of the margins against PCMI clad failure. The Peregrine fuel performance code has been developed as a part the Consortium of Advanced Simulations of Light Water Reactors (CASL) to consider the inherently multi-physics and multi-dimensional mechanisms that control fuel behavior, including cladding failure by the presence of MPS defects. This paper presents an evaluation of the cladding stress concentrations as a function of MPS defect geometry. The results are the first step in a probabilistic approach to assess cladding failure during power maneuvers. This analysis provides insight into how varying pellet defect geometries affect the distribution of the cladding stress and fuel and cladding temperature and will be used to develop stress concentration factors for 2D and 3D models.

  3. Variability in the coupling between sea surface temperature and wind stress in the global coastal ocean

    Science.gov (United States)

    Wang, Yuntao; Castelao, Renato M.

    2016-08-01

    Mesoscale ocean-atmosphere interaction between sea surface temperature (SST) and wind stress throughout the global coastal ocean was investigated using 7 years of satellite observations. Coupling coefficients between crosswind SST gradients and wind stress curl and between downwind SST gradients and wind stress divergence were used to quantify spatial and temporal variability in the strength of the interaction. The use of a consistent data set and standardized methods allow for direct comparisons between coupling coefficients in the different coastal regions. The analysis reveals that strong coupling is observed in many mid-latitude regions throughout the world, especially in regions with strong fronts like Eastern and Western Boundary Currents. Most upwelling regions in Eastern Boundary Currents are characterized by strong seasonal variability in the strength of the coupling, which generally peaks during summer in mid latitudes and during winter at low latitudes. Seasonal variability in coastal regions along Western Boundary Currents is comparatively smaller. Intraseasonal variability is especially important in regions of strong eddy activity (e.g., Western Boundary Currents), being particularly relevant for the coupling between crosswind SST gradients and wind stress curl. Results from the analysis can be used to guide modeling studies, since it allows for the a priori identification of regions in which regional models need to properly represent the ocean-atmosphere interaction to accurately represent local variability.

  4. Secretion of byssal threads in Mytilus galloprovincialis: quantitative and qualitative values after spawning stress.

    Science.gov (United States)

    Babarro, Jose M F; Reiriz, María José Fernández

    2010-01-01

    The effect of spawning events of the mussel Mytilus galloprovincialis on both quantitative and qualitative values of byssus secretion and its associated attachment force was investigated. Byssogenesis rates and absorption efficiency values were significantly reduced after spawning of individuals. However, the maintenance of individuals under sub-optimal conditions (lack of microalgae in the diet) for a week caused no effect on thread's number. Surprisingly, the attachment force varied within a narrow range of values (1.7-1.9 N) with the exception of a significant drop in the experimental group spawned and kept unfed (1.0 N; P byssus highlighted a higher presence of the basic residues histidine and lysine in threads secreted by spawned individuals. The presence of both histidine and lysine residues in the byssal collagen is associated to the formation of cross-links and specifically histidine has a functionality with a pronounced effect on metal chelation to stabilise the integrity of the byssus. Results reported here evidence the necessity to integrate all components that eventually determines the attachment strength of the mussels to get more insight to the plasticity of such secretion. Morphology of the byssus (thickness) secreted under different endogenous conditions of mussels was the major parameter to explain variability in the attachment force. Moreover, aminoacidic composition as quality term of the byssus secreted may also contribute to understand the plasticity of this secretion and needs to be extended in further surveys.

  5. Market Value Estimation Models for Marine Surface Vessels with the Use of Multiple Regression Analysis.

    Science.gov (United States)

    1982-12-01

    which should be used when quantifying "value." Some common alternative measures may include terms such as book value, net realizable value , cur- rent...brokerage fee) [Ref. 1: p. 9-6]. Depending on whether or not there 15 are any preparation or brokerage costs, the net realizable value may be equivalent...of petroleum-carrying vessels to the realizable value of their scrap steel. For example, the Motor Vessel EXXON FLORENCE was recently sold in Taiwan

  6. Productivity and food value of Amaranthus cruentus under non-lethal salt stress

    Science.gov (United States)

    Macler, Bruce A.; Macelroy, Robert D.

    1989-01-01

    Experiments were carried out to analyze the effects of increasing salinity stress on growth, photosynthesis, and carbon allocation in the crop plant Amaranthus. Plants were germinated and grown in Hoagland's solution with NaCl concentrations of 0 to 1.0 percent. The limits of total salinity in the plant growth medium are investigated. For Amaranthus cruentus, germination, vegetative growth, flowering, seed development and yield were normal at salinities from 0 to 0.2 percent. Inhibition of these phases increased from o.2 to 0.4 percent salinity and was total above 0.5 percent with 1 percent salinity was lethal to all developmental phases. Onset of growth phases were not affected by salinity. Plants could not be adapted by gradually increasing salinity over days or weeks. Water uptake increased, while photosynthetic CO2 uptake decreased with increasing salinity on a dry weight basis during vegetative growth. Protein levels were unchanged with increasing salinity. Leaf starch levels were lower at salinities of 0.5 percent and above, while stem starch levels were not affected by these salinities. The evidence supports salt inhibition arising frm changes in primary biochemical processes rather than from effects on water relations. While not addressing the toxic effects of specific ions, it suggests that moderate salinity per se need not be a problem in space systems.

  7. X-ray measurement of residual stresses in laser surface melted Ti-6Al-4V alloy

    NARCIS (Netherlands)

    Robinson, J.M.; van Brussel, B.A.; de Hosson, J.T.M.; Reed, R.C.

    1996-01-01

    In this paper, we report on the residual stresses in laser surface melted Ti-6Al-4V, determined using X-ray diffraction methods. The principal result is that there is an increase in the transverse residual stress with each successive, overlapping laser track. The result can be used to explain the ob

  8. Global analysis of ocean surface wind and wind stress using a general circulation model and Seasat scatterometer winds

    Science.gov (United States)

    Kalnay, E.; Atlas, R.

    1986-01-01

    Instantaneous and 15-day time-averaged fields of surface wind, wind stress, curl of the wind stress, and wind divergence are presented. These fields are derived from the Goddard Laboratory for Atmospheres four-dimensional analysis/forecast cycle, for the period September 6-30, 1978, using conventional data, satellite temperature soundings, cloud-track winds, and subjectively dealiased Seasat scatterometer winds.

  9. High yield stress associated with capillary attraction between alumina surfaces in the presence of low molecular weight dicarboxylic acids.

    Science.gov (United States)

    Teh, E-Jen; Leong, Yee-Kwong; Liu, Yinong; Craig, Vincent S J; Walsh, Rick B; Howard, Shaun C

    2010-03-02

    Adsorbed low molecular weight charged molecules are known to give rise to a range of surface forces that affect the rheological behavior of oxide dispersions. The behavior of dicarboxylic acid bolaform compounds in alumina slurry was investigated to determine the influence of the molecular structure on the nanoscale interactions between alumina surfaces and on the macroscopic properties of the slurry. The surface forces in dispersions and between a single particle and a flat surface were characterized by yield stress and atomic force microscopy (AFM) respectively. Absorbed muconic acid increased the yield stress of the alumina system, which indicates an additional attractive interaction between the particles. Adsorbed trans,trans (TT) muconic acid resulted in a much higher yield stress than cis,cis (CC) muconic acid. Force-distance data obtained via AFM displayed features indicating the presence of a capillary force attraction at low pH between the alumina surfaces when TT and CC muconic acids were adsorbed at high surface coverage. This force appeared to explain the high yield stress at low pH (pH 3.6), but the absence of a net attractive force at higher pH (pH 5) did not correlate with the yield stress results. At low pH, the muconic acids become less soluble in the confined space between the interacting surfaces resulting in the formation of an "oily" muconic acid phase located between the interacting surfaces. The nanosized "oil" phase is the source of the capillary force.

  10. Diagnostic value of clonality of surface immunoglobulin light and heavy chains in malignant lymphoproliferative disorders.

    Science.gov (United States)

    Batata, A; Shen, B

    1993-08-01

    Cell suspensions from the peripheral blood of B-chronic lymphoid leukemias (B-CLL, n = 274) and reactive lymphocytosis (RLC, n = 132) and from solid tissue samples of B-non-Hodgkin's lymphoma (B-NHL, n = 466) and reactive lymphadenopathy (RLA, n = 324) were analyzed to evaluate the diagnostic value of clonality of L- and H- chains in B-CLL and B-NHL. Cutoff levels for monoclonal L-chain (mono-L) and monoclonal H-chain (mono-H) were defined. In B-CLL, the association patterns of L- and H- chains were as follows: mono-L/mono-H, 245 cases (89.42%); mono-L/polyclonal H chain (poly-H), 4 (1.46%); polyclonal L chain (poly-L)/mono-H, 2 (0.73%); poly-L/poly-H, 2 (0.73%); undetected (und)-L/mono-H, 6 (2.19%); and und-L/und-H, 15 (5.47%). In B-NHL, the association patterns were mono-L/mono-H, 433 cases (92.92%); mono-L/poly-H, 4 (0.86%); poly-L/mono-H, 8 (1.72%); poly-L/poly-H, 2 (0.43%); und-L/mono-H, 4 (0.86%); and und-L/und-H, 15 (3.22%). Monoclonality of H chains are complementary to L-chain restriction, especially in the cases with poly-L or und-L, and should be considered as a positive criterion in determining surface immunoglobulin (SIg) clonality. Monoclonality of SIg assessed by both L and H chains is both sensitive and specific for the diagnosis of B-CLL and B-NHL, and their differentiation from RLC and RLA, since none of the cases of RLC and RLA showed monoclonal SIg.

  11. The Contribution of Io-Raised Tides to Europa's Diurnally-Varying Surface Stresses

    Science.gov (United States)

    Rhoden, Alyssa Rose; Hurford, Terry A,; Manga, Michael

    2011-01-01

    Europa's icy surface records a rich history of geologic activity, Several features appear to be tectonic in origin and may have formed in response to Europa's daily-varying tidal stress [I]. Strike-slip faults and arcuate features called cycloids have both been linked to the patterns of stress change caused by eccentricity and obliquity [2J[3]. In fact, as Europa's obliquity has not been directly measured, observed tectonic patterns arc currently the best indicators of a theoretically supported [4] non-negligible obliquity. The diurnal tidal stress due to eccentricity is calculated by subtracting the average (or static) tidal shape of Europa generated by Jupiter's gravitational field from the instantaneous shape, which varies as Europa moves through its eccentric orbit [5]. In other words, it is the change of shape away from average that generates tidal stress. One might expect tidal contributions from the other large moons of Jupiter to be negligible given their size and the height of the tides they raise on Europa versus Jupiter's mass and the height of the tide it raises on Europa, However, what matters for tidally-induced stress is not how large the lo-raised bulge is compared to the Jupiter-raised bulge but rather the differences bet\\Veen the instantaneous and static bulges in each case. For example, when Europa is at apocenter, Jupiter raises a tide 30m lower than its static tide. At the same time, 10 raises a tide about 0.5m higher than its static tide. Hence, the change in Io's tidal distortion is about 2% of the change in the Jovian distortion when Europa is at apocenter

  12. Value of the pudendal nerves terminal motor latency measurements in the diagnosis of occult stress urinary incontinence

    Institute of Scientific and Technical Information of China (English)

    ZHU Lan; HAI Ning; LANG Jing-he; YU Shi-yun; LI Bin; WONG Felix

    2011-01-01

    Background Occult stress urinary incontinence may lead to de novo stress urinary incontinence after pelvic floor repair surgery.A measurement of pudendal nerve terminal motor latency can reflect the integrity of the nerves.We aimed to explore the value of pudendal nerve terminal motor latency in the diagnosis of occult stress urinary incontinence in pelvic organ prolapse patients.Methods Ten patients with stress urinary incontinence (SUI group),10 with SUI and uterine or vaginal prolapse (POP+SUI group) and 10 with uncomplicated uterine or vaginal prolapse (POP group) were evaluated for their pudendal nerve terminal motor latency using a keypoint electromyogram.Results The amplitude of positive waves was between 0.1 and 0.2 mV.The nerve terminal motor latency was between 1.44 and 2.38 ms.There was no significant difference in the wave amplitudes of pudendal nerve evoked action potential among the three different groups (P >0.05).The pudendal nerve latency of the SUI group,POP+SUI group and POP group were (2.9±0.7) seconds,(2.8±0.7) seconds and (1.9±0.5) seconds respectively.The difference between the SUI group and POP+SUI group was not statistically significant (P >0.05),whereas the difference between the SUI and POP groups and between the POP+SUI and POP groups were statistically significant (P <0.05).There was a positive correlation between pudendal nerve latency and the severity of SUI; the correlation coefficient was 0.720 (P <0.01).Conclusions Patients with SUI may have some nerve demyelination injuries in the pudendal nerve but the damage might not involve the nerve axons.The measurement of pudendal nerve latency may be useful for the diagnosis of SUI in POP patients.

  13. The value of core lab stress echocardiography interpretations: observations from the ISCHEMIA Trial.

    Science.gov (United States)

    Kataoka, Akihisa; Scherrer-Crosbie, Marielle; Senior, Roxy; Gosselin, Gilbert; Phaneuf, Denis; Guzman, Gabriela; Perna, Gian; Lara, Alfonso; Kedev, Sasko; Mortara, Andrea; El-Hajjar, Mohammad; Shaw, Leslee J; Reynolds, Harmony R; Picard, Michael H

    2015-12-18

    Stress echocardiography (SE) is dependent on subjective interpretations. As a prelude to the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) Trial, potential sites were required to submit two SE, one with moderate or severe left ventricular (LV) myocardial ischemia and one with mild ischemia. We evaluated the concordance of site and core lab interpretations. Eighty-one SE were submitted from 41 international sites. Ischemia was classified by the number of new or worsening segmental LV wall motion abnormalities (WMA): none, mild (1 or 2) or moderate or severe (3 or more) by the sites and the core lab. Core lab classified 6 SE as no ischemia, 35 mild and 40 moderate or greater. There was agreement between the site and core in 66 of 81 total cases (81%, weighted kappa coefficient [K] =0.635). Agreement was similar for SE type - 24 of 30 exercise (80%, K = 0.571) vs. 41 of 49 pharmacologic (84%, K = 0.685). The agreement between poor or fair image quality (27 of 36 cases, 75%, K = 0.492) was not as good as for the good or excellent image quality cases (39 of 45 cases, 87%, K = 0.755). Differences in concordance were noted for degree of ischemia with the majority of discordant interpretations (87%) occurring in patients with no or mild LV myocardial ischemia. While site SE interpretations are largely concordant with core lab interpretations, this appears dependent on image quality and the extent of WMA. Thus core lab interpretations remain important in clinical trials where consistency of interpretation across a range of cases is critical. ClinicalTrials.gov NCT01471522.

  14. Spatially Complete Global Spectral Surface Albedos: Value-Added Datasets Derived from Terra MODIS Land Products

    Science.gov (United States)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Land surface albedo is an important parameter in describing the radiative properties of the earth s surface as it represents the amount of incoming solar radiation that is reflected from the surface. The amount and type of vegetation of the surface dramatically alters the amount of radiation that is reflected; for example, croplands that contain leafy vegetation will reflect radiation very differently than blacktop associated with urban areas. In addition, since vegetation goes through a growth, or phenological, cycle, the amount of radiation that is reflected changes over the course of a year. As a result, albedo is both temporally and spatially dependant upon global location as there is a distribution of vegetated surface types and growing conditions. Land surface albedo is critical for a wide variety of earth system research projects including but not restricted to remote sensing of atmospheric aerosol and cloud properties from space, ground-based analysis of aerosol optical properties from surface-based sun/sky radiometers, biophysically-based land surface modeling of the exchange of energy, water, momentum, and carbon for various land use categories, and surface energy balance studies. These projects require proper representation of the surface albedo s spatial, spectral, and temporal variations, however, these representations are often lacking in datasets prior to the latest generation of land surface albedo products.

  15. Microstructuring of thermo-mechanically highly stressed surfaces final report of the DFG research group 576

    CERN Document Server

    Rienäcker, Adrian; Knoll, Gunter; Bach, Friedrich-Wilhelm; Maier, Hans; Reithmeier, Eduard; Dinkelacker, Friedrich

    2015-01-01

    This contributed volume presents the final research results of the DFG Research Group 576, which is a joint initiative of five different institutes of the Leibniz Universität Hannover and the Universität Kassel, Germany. The research of the DFG Research Group 576 focuses on improving the tribological behavior of thermomechanically highly stressed surfaces, particularly on cylinder liner for combustion engines. The target audience primarily comprises researchers and experts in the field but the book may also be beneficial for graduate students who want to specialize in the field.

  16. The additional value of first pass myocardial perfusion imaging during peak dose of dobutamine stress cardiac MRI for the detection of myocardial ischemia

    NARCIS (Netherlands)

    Lubbers, Daniel D.; Janssen, Caroline H. C.; Kuijpers, Dirkjan; Van Dijkman, Paul R. M.; Overbosch, Jelle; Willems, Tineke P.; Oudkerk, Matthijs

    2008-01-01

    Purpose of this study was to assess the additional value of first pass myocardial perfusion imaging during peak dose of dobutamine stress Cardiac-MR (CMR). Dobutamine Stress CMR was performed in 115 patients with an inconclusive diagnosis of myocardial ischemia on a 1.5 T system (Magnetom Avanto, Si

  17. Stress

    Science.gov (United States)

    ... diabetes. Shopdiabetes.org: Your Stress-Free System for Family Dinners! - 2017-03-book-oclock-scramble.html Shopdiabetes.org Your Stress-Free System for Family Dinners! A year of delicious meals to help prevent ...

  18. Stress

    Science.gov (United States)

    ... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  19. Enhanced surface recombination in a-Si:H solar cells caused by light stress

    Science.gov (United States)

    Kusian, W.; Pfleiderer, H.

    1991-08-01

    The change of the spectral photocurrent characteristics of amorphous silicon pin solar cells with light induced degradation is compared with the effect of slightly doping the ``i-layer''. Both treatments yield similar results. Light stress lets the primary photocurrent, measured with blue light, decrease and the secondary photocurrent, measured with red light, increased. The similar change occurs when a slight n-doping of the ``i-layer'' is replaced by a slight p-doping. A simple interpretation in terms of unfirom fields and preponderant surface recombination is possible and will be outlined. We additionally resort to numerical similations. Degradation is to be simulated by the introduction of stronger recombination. The crombination rate will be distributed in space. We indeed find that enhanced surface recombination plays the key role in guiding the simulation towards our experiment.

  20. Analysis of distribution rule of surface stress on cross wedge rolling contact zone by finite element method

    Science.gov (United States)

    Shu, Xuedao; Li, Lianpeng; Hu, Zhenghuan

    2005-12-01

    Contact surface of cross-wedge rolling is a complicated space surface and distribution rule of contact surface stress is very complicated. So far, its analyzed result was still based on slippery line method. Designing mould and actual production mainly depend on experiential factor. Application and development of cross-wedge rolling was baffled seriously. Based on the forming characteristics of cross-wedge rolling with flat wedge-shape, the ANSYS/DYNA software was developed secondly on the basis of itself, and the corresponding command program was compiled. Rolling process of cross-wedge rolling with flat wedge-shape was simulated successfully. Through simulation, space surface shape of contact surface was achieved, and distribution rule of contact surface stress was analyzed detailed and obtained. The results provide important theoretical foundation for avoiding appearing bug on surface of rolled part, instructing to design cross-wedge mould and confirming force and energy parameter.

  1. Deformation of Cases in High Capacitance Value Wet Tantalum Capacitors under Environmental Stresses

    Science.gov (United States)

    Teverovsky, Alexander

    2016-01-01

    Internal gas pressure in hermetic wet tantalum capacitors is created by air, electrolyte vapor, and gas generated by electrochemical reactions at the electrodes. This pressure increases substantially with temperature and time of operation due to excessive leakage currents. Deformation of the case occurs when the internal pressure exceeds pressure of the environments and can raise significantly when a part operates in space. Contrary to the cylinder case wet tantalum capacitors that have external sealing by welding and internal sealing provided by the Teflon bushing and crimping of the case, no reliable internal sealing exists in the button case capacitors. Single seal design capacitors are used for high capacitance value wet tantalum capacitors manufactured per DLA L&M drawings #04003, 04005, and 10011, and require additional analysis to assure their reliable application in space systems. In this work, leakage currents and case deformation of button case capacitors were measured during different environmental test conditions. Recommendations for derating, screening and qualification testing are given. This work is a continuation of a series of NEPP reports related to quality and reliability of wet tantalum capacitors.

  2. Comparison of Oxidative Stresses Mediated by Different Crystalline Forms and Surface Modification of Titanium Dioxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Karim Samy El-Said

    2015-01-01

    Full Text Available Titanium dioxide nanoparticles (TiO2 NPs are manufactured worldwide for use in a wide range of applications. There are two common crystalline forms of TiO2 anatase and rutile with different physical and chemical characteristics. We previously demonstrated that an increased DNA damage response is mediated by anatase crystalline form compared to rutile. In the present study, we conjugated TiO2 NPs with polyethylene glycol (PEG in order to reduce the genotoxicity and we evaluated some oxidative stress parameters to obtain information on the cellular mechanisms of DNA damage that operate in response to TiO2 NPs different crystalline forms exposure in hepatocarcinoma cell lines (HepG2. Our results indicated a significant increase in oxidative stress mediated by the anatase form of TiO2 NPs compared to rutile form. On the other hand, PEG modified TiO2 NPs showed a significant decrease in oxidative stress as compared to TiO2 NPs. These data suggested that the genotoxic potential of TiO2 NPs varies with crystalline form and surface modification.

  3. Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

    Science.gov (United States)

    Lusher, Amy L.; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

    2015-10-01

    Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

  4. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    Science.gov (United States)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-02-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD® BacLight™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria.

  5. A novel PDMS micro membrane biosensor based on the analysis of surface stress.

    Science.gov (United States)

    Sang, Shengbo; Witte, Hartmut

    2010-07-15

    The biological and medical application of biosensors is more and more important with the development of technology and society. Detection of cells and biological molecules utilizing biosensors based on the analysis of surface stress would facilitate inexpensive and high-throughput test and diagnosis. This paper presents a biocompatible surface stress-based polydimethylsiloxane (PDMS) micro membrane biosensor. Each biosensor chip consists of two available PDMS micro membranes, one acts as active membrane and the other as reference. Biosensors were functionalized using different functional materials respectively: MUA (11 Mercapto 1 undecanoicacid), MUO (11 Mercapto 1 undecanol) and DOT (Dodecane thiol). Two biosensor test systems were built based on a white light interferometer and a fiber optic interferometer respectively. Finally, testing experiments using Escherichia coli (E. coli) were performed based on the biosensor test systems we built. The results of the experiments showed that the MUA is a better functional material to functionalize the biosensor membranes than MUO and DOT for E. coli detection, some properties of E. coli, such as healthily living and dead status, can be analyzed based on the PDMS micro membrane biosensors.

  6. Effect of pH Value on Stress Corrosion Cracking of X70 Pipeline Steel in Acidic Soil Environment

    Institute of Scientific and Technical Information of China (English)

    Zhiyong LIU; Cuiwei DU; Xin ZHANG; Fuming WANG; Xiaogang LI

    2013-01-01

    The effect of pH value on the stress corrosion cracking (SCC) of API X70 pipeline steel in simulated acidic soil solutions was investigated by using slow strain rate test,electrochemical polarization curves,electrochemical impedance spectroscopy,and scanning electron microscopy.pH plays an important role in the susceptibility and electrochemical mechanism of SCC.The pH higher than 5 has no significant effect on electrochemical processes.By contrast,the pH lower than 5 intensifies cathodic hydrogen evolution reactions,thus increasing the cathodic current and corrosion potential.Under different pH values,the SCC mechanism of X70 pipeline steel varies among anodic dissolution (AD),hydrogen embrittlement (HE),and the combination of AD and HE (AD + HE) with variations of applied potential.At-850 mVSCE,the SCC mechanism is HE if pH is less than 4 or AD + HE if pH value is more positive.

  7. Surface chemistry regulates the sensitivity and tolerability of osteoblasts to various magnitudes of fluid shear stress.

    Science.gov (United States)

    Li, Yan; Wang, Jinfeng; Xing, Juan; Wang, Yuanliang; Luo, Yanfeng

    2016-12-01

    Scaffolds provide a physical support for osteoblasts and act as the medium to transfer mechanical stimuli to cells. To verify our hypothesis that the surface chemistry of scaffolds regulates the perception of cells to mechanical stimuli, the sensitivity and tolerability of osteoblasts to fluid shear stress (FSS) of various magnitudes (5, 12, 20 dynes/cm(2) ) were investigated on various surface chemistries (-OH, -CH3 , -NH2 ), and their follow-up effects on cell proliferation and differentiation were examined as well. The sensitivity was characterized by the release of adenosine triphosphate (ATP), nitric oxide (NO) and prostaglandin E2 (PGE2 ) while the tolerability was by cellular membrane integrity. The cell proliferation was characterized by S-phase cell fraction and the differentiation by ALP activity and ECM expression (fibronectin and type I collagen). As revealed, osteoblasts demonstrated higher sensitivity and lower tolerability on OH and CH3 surfaces, yet lower sensitivity and higher tolerability on NH2 surfaces. Observations on the focal adhesion formation, F-actin organization and cellular orientation before and after FSS exposure suggest that the potential mechanism lies in the differential control of F-actin organization and focal adhesion formation by surface chemistry, which further divergently mediates the sensitivity and tolerability of ROBs to FSS and the follow-up cell proliferation and differentiation. These findings are essentially valuable for design/selection of desirable surface chemistry to orchestrate with FSS stimuli, inducing appropriate cell responses and promoting bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2978-2991, 2016.

  8. Stress-strain curves of adsorbed protein layers at the air/water interface measured with surface shear rheology

    NARCIS (Netherlands)

    Martin, A.; Bos, M.; Stuart, M.C.; Vliet, T. van

    2002-01-01

    Interfacial shear properties of adsorbed protein layers at the air/water interface were determined using a Couette-type surface shear rheometer. Such experiments are often used to determine a steady-state ratio between stress and rate of strain, which is then denoted as "surface shear viscosity". Ho

  9. A summary of the sources of input parameter values for the Waste Isolation Pilot Plant final porosity surface calculations

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, B.M.

    1997-08-01

    A summary of the input parameter values used in final predictions of closure and waste densification in the Waste Isolation Pilot Plant disposal room is presented, along with supporting references. These predictions are referred to as the final porosity surface data and will be used for WIPP performance calculations supporting the Compliance Certification Application to be submitted to the U.S. Environmental Protection Agency. The report includes tables and list all of the input parameter values, references citing their source, and in some cases references to more complete descriptions of considerations leading to the selection of values.

  10. Impact of atomic-scale surface morphology on the size-dependent yield stress of gold nanoparticles

    Science.gov (United States)

    Yang, Liang; Bian, Jian-Jun; Wang, Gang-Feng

    2017-06-01

    Size-dependent mechanical properties have been revealed for nanowires, nanopillars and nanoparticles. On the surfaces of these nanosized elements, discrete atomic-scale steps will be naturally generated, however their impact on the mechanical properties and deformation has seldom been a concern. In this paper, large-scale molecular dynamics simulations are conducted to calculate the yield stress of gold nanoparticles under compression. In addition to absolute particle size, atomic-scale surface morphology induces significant fluctuation of the yield stress. An analytical relation is advanced to predict the yield stress of nanoparticles accounting for the influence of both size and surface morphology, which agrees well with atomic simulations. This study illuminates an important mechanism in nanosized elements, atomic-scale surface steps.

  11. Predictive value of familiality, stressful life events and gender on the course of obsessive-compulsive disorder.

    Science.gov (United States)

    Goldberg, Ximena; Soriano-Mas, Carles; Alonso, Pino; Segalàs, Cinto; Real, Eva; López-Solà, Clara; Subirà, Marta; Via, Esther; Jiménez-Murcia, Susana; Menchón, José M; Cardoner, Narcís

    2015-10-01

    Familiality, stressful life events (SLE) and gender significantly affect the onset of obsessive-compulsive disorder (OCD). However, their combined impact on the probability of OCD chronicity is largely unknown. With the objective of clarifying their predictive value, we tested a model of interaction effects between these influences. A sample of 449 patients with OCD was systematically assessed for familial loading, exposure to stressful life events, gender and course of the disease at the OCD referral unit at Bellvitge University Hospital. Multiple ordinal logistic regression was used to test interaction models. Familiality presented a main negative association with chronicity (OR=0.83, CI97.5%=0.70-0.98). This association was additively moderated by both exposure to SLE before onset and gender, and showed a positive slope among female patients not exposed to SLE before onset (Familiality*SLEbo: OR=0.69, CI97.5%=0.47-1; Familiality*gender: OR=1.30, CI97.5%=0.91-1.84). The findings are based on cross-sectional data. Assessment of course is based on a retrospective measure, which may imply the possibility of overestimation of chronicity. The predictive value of familiality on the course of OCD is only partially informative as both SLEbo and gender modify the association. When other risk factors are included in the model, familiality may predict decreased chances of chronicity. The mediation effects identified could explain the discrepancies found in previous research on this topic. Increased chances of presenting a chronic course of OCD may be found in association with familial vulnerability among female patients not exposed to SLEbo. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Spatially Complete Surface Albedo Data Sets: Value-Added Products Derived from Terra MODIS Land Products

    Science.gov (United States)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Spectral land surface albedo is an important parameter for describing the radiative properties of the Earth. Accordingly it reflects the consequences of natural and human interactions, such as anthropogenic, meteorological, and phenological effects, on global and local climatological trends. Consequently, albedos are integral parts in a variety of research areas, such as general circulation models (GCMs), energy balance studies, modeling of land use and land use change, and biophysical, oceanographic, and meteorological studies. Recent observations of diffuse bihemispherical (white-sky) and direct beam directional hemispherical (black-sky ) land surface albedo included in the MOD43B3 product from MODIS instruments aboard NASA's Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal characteristics. Cloud and seasonal snow cover, however, curtail retrievals to approximately half the global land surfaces on an annual equal-angle basis, precluding MOD43B3 albedo products from direct inclusion in some research projects and production environments.

  13. Smell identification of spices using nanomechanical membrane-type surface stress sensors

    Science.gov (United States)

    Imamura, Gaku; Shiba, Kota; Yoshikawa, Genki

    2016-11-01

    Artificial olfaction, that is, a chemical sensor system that identifies samples by smell, has not been fully achieved because of the complex perceptional mechanism of olfaction. To realize an artificial olfactory system, not only an array of chemical sensors but also a valid feature extraction method is required. In this study, we achieved the identification of spices by smell using nanomechanical membrane-type surface stress sensors (MSS). Features were extracted from the sensing signals obtained from four MSS coated with different types of polymers, focusing on the chemical interactions between polymers and odor molecules. The principal component analysis (PCA) of the dataset consisting of the extracted parameters demonstrated the separation of each spice on the scatter plot. We discuss the strategy for improving odor identification based on the relationship between the results of PCA and the chemical species in the odors.

  14. Status of oxidative stress on lesional skin surface of plantar warts.

    Science.gov (United States)

    Arican, O; Ozturk, P; Kurutas, E B; Unsal, V

    2013-03-01

    Warts are abnormal skin growths caused by human papilloma virus (HPV) infections within the skin of the patients. Sometimes the disease is difficult to treatment, and also, the relationship between HPV and some forms of skin cancers is important. The cutaneous oxidative stress status of warts is absent in the literature. To evaluate the role of oxidative stress in affected skin areas in a group of patients with plantar warts. Thirty-six consecutive patients with a diagnosis of plantar warts were enrolled. The samples were obtained by scraping the skin surface. Superoxide dismutase (SOD) and catalase (CAT) activities and malondialdehyde (MDA) levels were measured spectrophotometrically at samples. The SOD activity was significantly lower, and the MDA level was significantly higher on the lesional area than on the non-lesional area (P warts may play a role in pathogenesis of the disease. The addition of topical drugs with antioxidative effects may be valuable in the treatment of warts. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

  15. NbSe{sub 3}: Fermi surface and magnetoresistance under uniaxial stress

    Energy Technology Data Exchange (ETDEWEB)

    Tessema, G.X.; Gamble, B.K.; Kuh, J.; Skove, M.J. [Clemson Univ., SC (United States); Lacerda, A.H.; Bennett, M. [Clemson Univ., SC (United States); NHMFL, Los Alamos National Lab. (United States)

    1999-12-01

    The Fermi surface of NbSe{sub 3} below the two CDW transitions is still not very clear. Large magnetoresistance and giant quantum oscillations have been seen at low temperature below the second CDW transition. The SdH oscillations are attributed to one or several small pieces of electron or hole pockets spared by the two CDW transitions at 145 and 59 K. In a previous low field study ({mu}{sub 0}H<8 T) of the transverse magnetoresistance (H in the (b,c) plane) we have shown that the extremal area of one of these pockets decreases linearly with strain, {epsilon}, vanishing at {epsilon} = 2.5%. Here we extend our study into the high magnetic field regime (pulsed 60 T) and investigate the effect of uniaxial stress on the magnetoresistance (I//H). Our high field study is consistent with the fermiology study and shows that uniaxial stress leads to the obliteration of a small closed pocket. Above 1% strain the magnetoresistance is linear with H with no sign of saturation. (orig.)

  16. Interrogating surface state of isolated and agglomerated PbS quantum dots with solvent-induced stress

    Science.gov (United States)

    Sher, Pin-Hao; Wang, Juen-Kai

    2017-04-01

    Applications of quantum dots (QDs) are often obstructed by the associated surface electronic states that quench photoluminescence (PL) and hinder charge transport. Preventing this is still largely being stymied owing to the lack of means to regulate their presence. Dispersing PbS QDs in toluene, we show that varying the solvent temperature offers a way of modulating their surface electronic state. A comprehensive energy-transfer model explains all the anomalous temperature-dependent behavior of the absorption and PL, explicitly revealing the PL quenching dynamics of isolated QDs due to the induced surface state by imposing solvent stress on their surface ligands. This study demonstrates that the local stress induced by a solvent can serve as a ‘switch’ for the surface electronic states of QDs, which is enabled by the well-studied thermo-physical properties of a liquid solvent.

  17. Temperature limit values for cold touchable surfaces ' ColdSurf ' : final report

    NARCIS (Netherlands)

    Holmer, I.; Havenith, G.; Hartog, E.A. den; Rintamaki, H.; Malchaire, J.

    2000-01-01

    The aim of the project was to find and compile information on human responses to contact with cold surfaces. The work has covered 1) literature search and field survey; 2) experimental studies with human subjects; 3) simulation by modeling; 4) instrumentation (artificial finger), 5) establishment of

  18. Perfluorinated poly(dimethylsiloxane) via the covalent attachment of perfluoroalkylsilanes on the oxidized surface: Effects on zeta-potential values

    Science.gov (United States)

    Sun, Peiling; Horton, J. Hugh

    2013-04-01

    Poly(dimethylsiloxane) (PDMS) is a widely-used polymer in microfluidic devices due to its range of physical and chemical properties suitable for molding micron-sized features. However, its hydrophobicity also leads to some limitations: it poorly supports electro-osmotic flow, and can be incompatible with biomolecules and with many organic solvents. Surface modification is commonly used to vary PDMS surface properties to make it more suitable for specific microfluidic applications. Here, we report on the surface modification of PDMS using perfluoroalkane-triethoxysilanes, via the covalent attachment of triethoxysilane groups on plasma-oxidized PDMS. A device constructed from such fluorinated materials could be used for separating fluorous-tagged proteins or peptides. Modified PDMS were characterized using a range of surface analytical methods. In particular, zeta- (ζ-) potential values at the interfaces of both modified and unmodified PDMS and under varying pH conditions were measured, as ζ-potential is an essential parameter to support electroosmotic flow (EOF), a common pumping method in microfluidic devices. The results showed the length of fluorinated alkane chain has significant effect on the density of surface modifying species and topography following modification. In addition, the perfluorinated modification increases the magnitude of the ζ-potential at the PDMS interface when compared to that of native PDMS, increasing the electro-osmotic flow rate, over a wide pH range. The modified surface is resistant to the diffusion of PDMS oligomers that affects other PDMS surface modification processes.

  19. The Impact of Racial Identity, Ethnic Identity, Asian Values and Race-Related Stress on Asian Americans and Asian International College Students’ Psychological Well-Being

    OpenAIRE

    Iwamoto, Derek Kenji; LIU, WILLIAM MING

    2010-01-01

    The current study investigated the direct and moderating effects of racial identity, ethnic identity, Asian values, and race-related stress on positive psychological well-being among 402 Asian American and Asian international college students. Results revealed that the racial identity statuses Internalization, Immersion-Emersion, Dissonance, Asian values and Ethnic Identity Affirmation and Belonging were significant predictors of well-being. Asian values, Dissonance and Conformity were found ...

  20. Inter-comparison of four remote sensing based surface energy balance methods to retrieve surface evapotranspiration and water stress of irrigated fields in semi-arid climate

    Directory of Open Access Journals (Sweden)

    J. Chirouze

    2013-01-01

    Full Text Available Remotely sensed surface temperature can provide a good proxy for water stress level and is therefore particularly useful to estimate spatially distributed evapotranspiration. Instantaneous stress levels or instantaneous latent heat flux are deduced from the surface energy balance equation constrained by this equilibrium temperature. Pixel average surface temperature depends on two main factors: stress and vegetation fraction cover. Methods estimating stress vary according to the way they treat each factor. Two families of methods can be defined: the contextual methods, where stress levels are scaled on a given image between hot/dry and cool/wet pixels for a particular vegetation cover, and single-pixel methods which evaluate latent heat as the residual of the surface energy balance for one pixel independently from the others. Four models, two contextual (S-SEBI and a triangle method, inspired by Moran et al., 1994 and two single-pixel (TSEB, SEBS are applied at seasonal scale over a four by four km irrigated agricultural area in semi-arid northern Mexico. Their performances, both at local and spatial standpoints, are compared relatively to energy balance data acquired at seven locations within the area, as well as a more complex soil-vegetation-atmosphere transfer model forced with true irrigation and rainfall data. Stress levels are not always well retrieved by most models, but S-SEBI as well as TSEB, although slightly biased, show good performances. Drop in model performances is observed when vegetation is senescent, mostly due to a poor partitioning both between turbulent fluxes and between the soil/plant components of the latent heat flux and the available energy. As expected, contextual methods perform well when extreme hydric and vegetation conditions are encountered in the same image (therefore, esp. in spring and early summer while they tend to exaggerate the spread in water status in more homogeneous conditions (esp. in winter.

  1. Inter-comparison of four remote sensing based surface energy balance methods to retrieve surface evapotranspiration and water stress of irrigated fields in semi-arid climate

    Science.gov (United States)

    Chirouze, J.; Boulet, G.; Jarlan, L.; Fieuzal, R.; Rodriguez, J. C.; Ezzahar, J.; Er-Raki, S.; Bigeard, G.; Merlin, O.; Garatuza-Payan, J.; Watts, C.; Chehbouni, G.

    2013-01-01

    Remotely sensed surface temperature can provide a good proxy for water stress level and is therefore particularly useful to estimate spatially distributed evapotranspiration. Instantaneous stress levels or instantaneous latent heat flux are deduced from the surface energy balance equation constrained by this equilibrium temperature. Pixel average surface temperature depends on two main factors: stress and vegetation fraction cover. Methods estimating stress vary according to the way they treat each factor. Two families of methods can be defined: the contextual methods, where stress levels are scaled on a given image between hot/dry and cool/wet pixels for a particular vegetation cover, and single-pixel methods which evaluate latent heat as the residual of the surface energy balance for one pixel independently from the others. Four models, two contextual (S-SEBI and a triangle method, inspired by Moran et al., 1994) and two single-pixel (TSEB, SEBS) are applied at seasonal scale over a four by four km irrigated agricultural area in semi-arid northern Mexico. Their performances, both at local and spatial standpoints, are compared relatively to energy balance data acquired at seven locations within the area, as well as a more complex soil-vegetation-atmosphere transfer model forced with true irrigation and rainfall data. Stress levels are not always well retrieved by most models, but S-SEBI as well as TSEB, although slightly biased, show good performances. Drop in model performances is observed when vegetation is senescent, mostly due to a poor partitioning both between turbulent fluxes and between the soil/plant components of the latent heat flux and the available energy. As expected, contextual methods perform well when extreme hydric and vegetation conditions are encountered in the same image (therefore, esp. in spring and early summer) while they tend to exaggerate the spread in water status in more homogeneous conditions (esp. in winter).

  2. Spatio-temporal variability in sea surface wind stress near and off the east coast of Korea

    Institute of Scientific and Technical Information of China (English)

    NAM SungHyun; KIM Young Ho; PARK Kyung-Ae; KIM Kuh

    2005-01-01

    Sea surface wind stress variabilities near and off the east coast of Korea, are examined using 7 kinds of wind datasets from measurements at 2 coastal (land) stations and 2 ocean buoys,satellite scatterometer (QuikSCAT), and global reanalyzed products (ECMWF,NOGAPS,and NCEP/NCAR). Temporal variabilities are analyzed at 3 frequency bands; synoptic (2~20 d), intra-seasonal (20~90 d),and seasonal (>90 d).Synoptic and intra-seasonal variations are predominant near and off the Donghae City due to the passage of the mesoscale weather system. Seasonal variation is caused by southeastward wind stress during Asian winter monsoon. The sea surface wind stress from reanalyzed datasets,QuikSCAT and KMA-B measurements off the coast show good agreement in the magnitude and direction,which are strongly aligned with the alongshore direction. At the land-based sites,wind stresses are much weaker by factors of 3~10 due to the mountainous landmass on the east parts of Korea Peninsula. The first EOF modes(67 % ~70%) of wind stresses from reanalyzed and QuikSCAT data have similar structures of the strong southeastward wind stress in winter along the coast but show different curl structures at scales less than 200 kn due to the orographic effects. The second EOF modes (23 % ~25%)show southwestward wind stress in every September along the east coast of the North Korea

  3. Surface preparation for XRD residual stress measurements; Preparacao de superficie para medicao de tensoes residuais em soldagem por DRX

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Andrii; Oliveira, Bruno Jose de; Scotti, Americo, E-mail: asmwelder@gmail.com, E-mail: brunojoliveira7@gmail.com, E-mail: ascotti@mecanica.ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil)

    2016-10-15

    A characteristic feature of the X Ray Diffraction (XRD) method for stress determination is that measurements occur at a thin surface layer. Steel sheets come with surfaces modified by lamination, cleaning (sandblasting, grinding) and even corrosion, which induce residual stresses or roughness inherent to the material. Therefore, surface preparation prior to the residual stress measurement is essential, although no standard procedure seems to be available. A general recommendation is to remove a thin layer so that only residual stresses related to the welding process will be measured. In this study, the use of portable electrolytic equipment was evaluated for mechanized surface material removal. Chemical compositions of electrolytic solutions and the influence of current on the removed material, removal time and temperature during the process were studied. As a result, a suitable chemical solution for electro etching of low carbon steel was developed and a set of “soft” parameters that allowed the removal of about 300 um in a reasonable time was found. Higher currents reduce the removal time, yet increasing the consumption of the solution and plate temperature (which could adversely alter the microstructure or generate thermal stresses). Furthermore, the influence of these parameters on the operability of the process was demonstrated. (author)

  4. Quantifying residual stress in nanoscale thin polymer films via surface wrinkling.

    Science.gov (United States)

    Chung, Jun Young; Chastek, Thomas Q; Fasolka, Michael J; Ro, Hyun Wook; Stafford, Christopher M

    2009-04-28

    Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and then trap polymer chains into nonequilibrium stressed conformations. In solvent-cast films, which are central to a wide range of technologies, residual stress can cause detrimental effects, including microscopic defect formation and macroscopic dimensional changes. Since residual stress is difficult to measure accurately, particularly in nanoscale thin polymer films, it remains a challenge to understand and control. We present here a quantitative method of assessing residual stress in polymer thin films by monitoring the onset of strain-induced wrinkling instabilities. Using this approach, we show that thin (>100 nm) polystyrene films prepared via spin-coating possess residual stresses of approximately 30 MPa, close to the crazing and yield stress. In contrast to conventional stress measurement techniques such as wafer curvature, our technique has the resolution to measure residual stress in films as thin as 25 nm. Furthermore, we measure the dissipation of residual stress through two relaxation mechanisms: thermal annealing and plasticizer addition. In quantifying the amount of residual stress in these films, we find that the residual stress gradually decreases with increasing annealing time and plasticizer amounts. Our robust and simple route to measure residual stress adds a key component to the understanding of polymer thin film behavior and will enable identification of more effective processing routes that mitigate the detrimental effects of residual stress.

  5. The diagnostic value of exfoliative cytology vs histopathology for ocular surface squamous neoplasia.

    Science.gov (United States)

    Semenova, Ekaterina A; Milman, Tatyana; Finger, Paul T; Natesh, Sribhargava; Kurli, Madhavi; Schneider, Susan; Iacob, Codrin E; McCormick, Steven A

    2009-11-01

    To determine the reliability and role of conjunctival exfoliative cytologic and histopathologic diagnosis of biopsied tissue in ocular surface squamous neoplasia. Retrospective review of an interventional case series of patients biopsied and treated for squamous conjunctival and corneal neoplasia. Forty-nine patients who underwent conjunctival cytologic analysis (n = 36), conjunctival biopsy (n = 35), or both were evaluated. For the purposes of this study, three ocular pathologists reviewed the results of cytologic and biopsied tissue in a masked fashion. Evaluation of cytologic smears revealed a 91% concordance in interpretation of conjunctival cytologic material as no dysplasia vs dysplasia. The concordance dropped to 59% in grading the degree of dysplasia. The cytologic material was found to be inadequate for interpretation in 1 case. Evaluation of subsequent biopsy revealed a 98% concordance between the pathologists in interpretation of biopsied tissue as no dysplasia vs any degree of dysplasia. The concordance decreased to 83% in grading the degree of dysplasia. Cytologic evaluation was capable of distinguishing a neoplastic from nonneoplastic process before tissue biopsy in 80% of cases. Ocular surface cytologic analysis is a simple, safe, and relatively noninvasive diagnostic tool. It was found helpful in detecting dysplasia before surgical resection. It was used in the settings of recurrent tumor and for follow-up care of patients treated with topical chemotherapy. Although cytologic smears cannot replace incisional or excisional biopsy for definitive diagnosis, exfoliative cytologic analysis can play an important role in the diagnosis and management of patients with ocular surface squamous neoplasia.

  6. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  7. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  8. Modulation of the adrenocortical response to acute stress with respect to brood value, reproductive success and survival in the Eurasian hoopoe.

    Science.gov (United States)

    Schmid, Baptiste; Tam-Dafond, Laura; Jenni-Eiermann, Susanne; Arlettaz, Raphaël; Schaub, Michael; Jenni, Lukas

    2013-09-01

    Reproducing parents face the difficult challenge of trading-off investment in current reproduction against presumed future survival and reproduction. Glucocorticoids are supposed to mediate this trade-off because the adrenocortical response to stress disrupts normal reproductive behaviour in favour of self-maintenance and own survival. According to the brood-value hypothesis, individuals with a low survival probability until the next reproductive season have to invest in current reproduction, a process driven by a down-regulation of their adrenocortical response. If the adrenocortical response to stress effectively mediates the trade-off between current reproduction versus future survival and reproduction, we expect a negative relationship with reproductive success and a positive correlation of the adrenocortical stress response with survival. We studied the relationship between corticosterone secretion in parents and their current brood value, reproductive success and survival in a short-lived multi-brooded bird, the Eurasian hoopoe Upupa epops. The adrenocortical response to acute handling stress was correlated with the brood value within the individual (first and second broods of the year) and between individuals. Birds breeding late in the season mounted a lower total corticosterone response to acute stress than birds breeding earlier, while females showed lower levels than males. We observed a negative relationship between the adrenocortical stress response and rearing success or fledging success in females, as predicted by the brood-value hypothesis. However, we could not evidence a clear link between the adrenocortical stress response and survival. Future research testing the brood-value hypothesis and trade-offs between current reproduction and future survival should also measure free corticosterone and carefully differentiate between cross-sectional (i.e. between-individual) and individual-based experimental studies.

  9. Influence of stress, temperature and crystal morphology on isothermal densification and specific surface area decrease of new snow

    Directory of Open Access Journals (Sweden)

    S. Schleef

    2014-10-01

    Full Text Available Laboratory-based, experimental data for the microstructural evolution of new snow are scarce, though applications would benefit from a quantitative characterization of the main influences. To this end, we have analyzed the metamorphism and concurrent densification of new snow under isothermal conditions by means of X-ray microtomography and compiled a comprehensive data set of 45 time series. In contrast to previous measurements on isothermal metamorphism on time scales of weeks to months, we analyzed the initial 24–48 h of snow evolution at a high temporal resolution of 3 hours. The data set comprised natural and laboratory-grown snow, and experimental conditions included systematic variations of overburden stress, temperature and crystal habit to address the main influences on specific surface area (SSA decrease rate and densification rate in a snowpack. For all conditions, we found a linear relation between density and SSA, indicating that metamorphism has an immediate influence for the densification of new snow. The slope of the linear relation, however, depends on the other parameters which were analyzed individually to derive a best-fit parameterization for the SSA decrease rate and densification rate. In the investigated parameter range, we found that the initial value of the SSA constituted the main morphological influence on the SSA decrease rate. In turn, the SSA decrease rate constituted the main influence on the densification rate.

  10. Incremental value of contrast myocardial perfusion to detect intermediate versus severe coronary artery stenosis during stress-echocardiography

    Directory of Open Access Journals (Sweden)

    Ugo Fabrizio

    2010-05-01

    Full Text Available Abstract Background We aimed to compare the incremental value of contrast myocardial perfusion imaging (MPI for the detection of intermediate versus severe coronary artery stenosis during dipyridamole-atropine echocardiography (DASE. Wall motion (WM assessment during stress-echocardiography demonstrates suboptimal sensitivity to detect coronary artery disease (CAD, particularly in patients with isolated intermediate (50%-70% coronary stenosis. Methods We performed DASE with MPI in 150 patients with a suspected chest pain syndrome who were given clinical indication to coronary angiography. Results and discussion When CAD was defined as the presence of a ≥50% stenosis, the addition of MPI increased sensitivity (+30% and decreased specificity (-14%, with a final increase in total diagnostic accuracy (+16%, p Conclusions The addition of MPI on top of WM analysis during DASE increases the diagnostic sensitivity to detect obstructive CAD, whatever its definition (≥50% or > 70% stenosis, but it is mainly driven by the sensitivity increase in the intermediate group (50%-70% stenosis. The total diagnostic accuracy increased only when defining CAD as ≥50% stenosis, since in patients with severe stenosis (> 70% the decrease in specificity is not counterbalanced by the minor sensitivity increase.

  11. Influence of Additive Manufactured Scaffold Architecture on the Distribution of Surface Strains and Fluid Flow Shear Stresses and Expected Osteochondral Cell Differentiation.

    Science.gov (United States)

    Hendrikson, Wim J; Deegan, Anthony J; Yang, Ying; van Blitterswijk, Clemens A; Verdonschot, Nico; Moroni, Lorenzo; Rouwkema, Jeroen

    2017-01-01

    Scaffolds for regenerative medicine applications should instruct cells with the appropriate signals, including biophysical stimuli such as stress and strain, to form the desired tissue. Apart from that, scaffolds, especially for load-bearing applications, should be capable of providing mechanical stability. Since both scaffold strength and stress-strain distributions throughout the scaffold depend on the scaffold's internal architecture, it is important to understand how changes in architecture influence these parameters. In this study, four scaffold designs with different architectures were produced using additive manufacturing. The designs varied in fiber orientation, while fiber diameter, spacing, and layer height remained constant. Based on micro-CT (μCT) scans, finite element models (FEMs) were derived for finite element analysis (FEA) and computational fluid dynamics (CFD). FEA of scaffold compression was validated using μCT scan data of compressed scaffolds. Results of the FEA and CFD showed a significant impact of scaffold architecture on fluid shear stress and mechanical strain distribution. The average fluid shear stress ranged from 3.6 mPa for a 0/90 architecture to 6.8 mPa for a 0/90 offset architecture, and the surface shear strain from 0.0096 for a 0/90 offset architecture to 0.0214 for a 0/90 architecture. This subsequently resulted in variations of the predicted cell differentiation stimulus values on the scaffold surface. Fluid shear stress was mainly influenced by pore shape and size, while mechanical strain distribution depended mainly on the presence or absence of supportive columns in the scaffold architecture. Together, these results corroborate that scaffold architecture can be exploited to design scaffolds with regions that guide specific tissue development under compression and perfusion. In conjunction with optimization of stimulation regimes during bioreactor cultures, scaffold architecture optimization can be used to improve

  12. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.

    2014-09-14

    © 2014 © The Author, 2014. Published by Oxford University Press; all rights reserved. For Permissions, please email: journals.permissions@oup.com. The steady flow of a slowly varying rivulet with prescribed flux in the azimuthal direction round a large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a solution corresponding to a rivulet flowing down at least part of one side of the cylinder. We consider both a rivulet with constant non-zero contact angle but slowly varying width (that is, de-pinned contact lines) and a rivulet with constant width but slowly varying contact angle (that is, pinned contact lines), and show that they have qualitatively different behaviour. When shear is present, a rivulet with constant non-zero contact angle can never run all the way from the top to the bottom of the cylinder, and so we consider the scenario in which an infinitely wide two-dimensional film of uniform thickness covers part of the upper half of the cylinder and \\'breaks\\' into a single rivulet with constant non-zero contact angle. In contrast, a sufficiently narrow rivulet with constant width can run all the way from the top to the bottom of the cylinder, whereas a wide rivulet can do so only if its contact lines de-pin, and so we consider the scenario in which the contact lines of a wide rivulet de-pin on the lower half of the cylinder.

  13. Metabolic Signatures of Oxidative Stress and Their Relationship with Erythrocyte Membrane Surface Roughness Among Workers of Manual Materials Handling (MMH).

    Science.gov (United States)

    Ghosh, Subrata; Acharyya, Muktish; Majumder, Titlee; Bagchi, Anandi

    2015-12-01

    Brickfield workers in India perform manual materials handling (MMH) and as a result, are at a high risk of developing oxidative stress. This results in an alteration of the various markers of metabolic oxidative stress at the cellular level. Since red blood cell (RBC) is the central point where oxygen, glucose-6-phosphate dehydrogenase (G-6-PD), and glutathione (GSH) are involved, the surface roughness and its alteration and modeling with respect to workers exposed to MMH may be considered as helpful determinants in predicting early damage to the cell and restoring better health to the exposed population, that is, the worker exposed to stress. Hence, nanometric analysis of the surface roughness of the RBC may serve as an early indicator of the stress-related damage in these individuals. The purpose of the study was to identify early red blood corpuscular surface damage profile in terms of linear modeling correlating various biochemical parameters. Linear modeling has been aimed to be developed in order to demonstrate how individual oxidative stress markers such as malondialdehyde (MDA), G-6-PD, and reduced GSH are related to the RBC surface roughness [root mean square (RMS)]. Conventional analysis of these biochemical responses were evaluated in MMH laborers (age varying between 18 years and 21 years) and a comparable control group of the same age group (with sedentary lifestyles). Peak expiratory flow rate (PEFR) and RBC surface analysis by atomic-force microscopy (AFM) and correlated scanning probe microscopy (SPM-analytical software) with corresponding image analysis were performed immediately after completion of standardized exercise (MMH) at the brickfield. A number of correlated significances and regressive linear models were developed among MDA, G-6-PD, GSH, and RBC surface roughness. It appears that these linear models might be instrumental in predicting early oxidative damages related to specific occupational hazards.

  14. On the value of frequency-dependent traveltime tomography for surface-seismic data

    Science.gov (United States)

    Jordi, Claudio; Schmelzbach, Cedric; Greenhalgh, Stewart

    2015-04-01

    Frequency-dependent traveltime tomography does not rely on the high-frequency assumption made in classical (asymptotic ray-theory based) tomography. By incorporating the influence of velocity structures in a nearby region (called the first Fresnel volume) around the central ray, it offers a more realistic and accurate representation of the actual physics of seismic wave propagation and thus, improved imaging of the subsurface is expected. Improvements in seismic imaging include the recovery of additional information on the subsurface model, enhanced (model) resolution and better detection and delineation of low velocity zones. It has been argued that finite-frequency effects on traveltimes may be more pronounced in near-surface imaging considering the typical seismic wavelengths and dimensions of heterogeneities compared to global-scale traveltime tomography. To account for the finite frequency characteristics of seismic data, a so-called fat-ray tomography algorithm was developed. The algorithm forms the sum of source and receiver (adjoint) traveltime fields, calculated by finite-difference modeling of the eikonal equation, to determine the necessary Fresnel volumes and sensitivity kernels for the tomographic inversion. Using different scale surface-seismic synthetic data examples, the imaging capabilities of the fat-ray tomography algorithm were investigated and compared to the results of classical ray tomography. The velocity fields used to generate the synthetic data were chosen to emulate two real field data sets, to which the fat-ray tomography was also applied. The first real data example is a large-scale data set (profile length > 10 km) acquired for hydrocarbon search; the second data set was recorded for high-resolution near-surface imaging of a Quaternary valley (profile length < 1 km). Resolution of the tomograms was assessed on the basis of checkerboard tests and a column sum of the sensitivity matrix. For the synthetic data examples as well as for the

  15. Methoxychlor and estradiol induce oxidative stress DNA damage in the mouse ovarian surface epithelium.

    Science.gov (United States)

    Symonds, Daniel A; Merchenthaler, Istvan; Flaws, Jodi A

    2008-09-01

    Estrogenic compounds such as 17beta-estradiol (E(2)) and methoxychlor (MXC) induce oxidative stress damage in breast cells and mouse ovarian follicles, respectively. However, little is known about whether estrogenic compounds cause oxidative stress in the ovarian surface epithelium (OSE). Thus, this work tested the hypothesis that E(2) and MXC cause oxidative stress in the OSE. To test this hypothesis, we employed an improved mouse tissue culture assay in which OSE cells were treated with hydrogen peroxide (H2O2; positive control), MXC, or E(2) +/- the anti-oxidant vitamin E, or progesterone. The cells then were subjected to a novel direct immunofluorescent assay in which cells in the microtiter plate were reacted with antibodies that detect oxidative damage to DNA (8-hydroxy-2'-deoxyguanosine). The signal was identified with a tyramide Alexa Fluor fluorescent probe and quantified by microfluorimetry. Correction for cellularity was carried out for each well with a fluorescent DNA dye system (CyQuant) at a different wavelength. After 24 h, the mean Alexa Fluor CyQuant ratio was 11.3 +/- 0.9 for controls, 132 +/- 15 for H2O2 treated positive control cells (p < or = 0.01 from control), 105 +/- 6.6 for E(2) treated cells (p < or = 0.01 from control), and 64 +/- 5.1 for MXC-treated cells (p < or = 0.01 from control). After 72 h, the mean ratio was 121 +/- 10.6 for controls, 391 +/- 23 for H2O2 treated cells (p < or = 0.01 from control), 200 +/- 15 for E(2) treated cells (p < or = 0.03), and 228 +/- 21 for MXC-treated cells (p < or = 0.01). Further, vitamin E, but not progesterone, protected OSE cells from E(2)- and MXC-induced oxidative damage. This study demonstrates the feasibility of direct immunofluorescent quantitation of DNA adducts in cell cultures without DNA extraction. Moreover, these data indicate that E(2) and MXC produce oxidative DNA damage in the OSE, and that this damage is prevented by the anti-oxidant vitamin E.

  16. Cell surface estrogen receptor alpha is upregulated during subchronic metabolic stress and inhibits neuronal cell degeneration.

    Directory of Open Access Journals (Sweden)

    Cristiana Barbati

    Full Text Available In addition to the classical nuclear estrogen receptor, the expression of non-nuclear estrogen receptors localized to the cell surface membrane (mER has recently been demonstrated. Estrogen and its receptors have been implicated in the development or progression of numerous neurodegenerative disorders. Furthermore, the pathogenesis of these diseases has been associated with disturbances of two key cellular programs: apoptosis and autophagy. An excess of apoptosis or a defect in autophagy has been implicated in neurodegeneration. The aim of this study was to clarify the role of ER in determining neuronal cell fate and the possible implication of these receptors in regulating either apoptosis or autophagy. The human neuronal cell line SH-SY5Y and mouse neuronal cells in primary culture were thus exposed to chronic minimal peroxide treatment (CMP, a form of subcytotoxic minimal chronic stress previously that mimics multiple aspects of long-term cell stress and represents a limited molecular proxy for neurodegenerative processes. We actually found that either E2 or E2-bovine serum albumin construct (E2BSA, i.e. a non-permeant form of E2 was capable of modulating intracellular cell signals and regulating cell survival and death. In particular, under CMP, the up-regulation of mERα, but not mERβ, was associated with functional signals (ERK phosphorylation and p38 dephosphorylation compatible with autophagic cytoprotection triggering and leading to cell survival. The mERα trafficking appeared to be independent of the microfilament system cytoskeletal network but was seemingly associated with microtubular apparatus network, i.e., to MAP2 molecular chaperone. Importantly, antioxidant treatments, administration of siRNA to ERα, or the presence of antagonist of ERα hindered these events. These results support that the surface expression of mERα plays a pivotal role in determining cell fate, and that ligand-induced activation of mER signalling exerts a

  17. Application of adsorption methods to determine the effect of pH and Cu-stress on the changes in the surface properties of the roots

    Science.gov (United States)

    Szatanik-Kloc, Alicja

    2014-10-01

    Rye plants were grown in a nutrient solution prepared according to Hoagland for 2 weeks at pH 7, next for 14 days at pH 4.5 (without Cu+2) and in the presence of 20, 50, or 100 mg dm-3 copper ions. The control plants were grown continuously at pH 7. The physicochemical surface properties of the roots were examined using two adsorbates - polar (water vapour) and non-polar (nitrogen). The surface properties of the roots grown at pH 4.5 without Cu+2 were apparently the same as those of controls. The roots of rye which grew in the presence of Cu+2 were characterized by lower (relative to controls) specific surface area values. Statistically significant differences in the size of the apparent surface area (determined by water vapour) were reported for roots incubated with copper ions at a concentration of 20 and 50 mg dm-3. The average water vapour adsorption energy of the root surface decreased under the stress conditions. There were no statistically significant differences for the free surface area and characteristic energy of nitrogen adsorption.

  18. Stress

    OpenAIRE

    Jensen, Line Skov; Lova, Lotte; Hansen, Zandra Kulikovsky; Schønemann, Emilie; Larsen, Line Lyngby; Colberg Olsen, Maria Sophia; Juhl, Nadja; Magnussen, Bogi Roin

    2012-01-01

    Stress er en tilstand som er meget omdiskuteret i samfundet, og dette besværliggør i en vis grad konkretiseringen af mulige løsningsforslag i bestræbelsen på at forebygge den såkaldte folkesygdom. Hovedkonklusionen er, at selv om der bliver gjort meget for at forebygge, er der ikke meget der aktivt kan sættes i værk for at reducere antallet af stressramte, før en fælles forståelse af stressårsager og effektiv stresshåndtering er fremlagt. Problemformuleringen er besvaret gennem en undersø...

  19. Connection Between Internal Structural Stresses of the Ist and the IInd kind and Operational Reliability of the Boiler Heating Surface

    Directory of Open Access Journals (Sweden)

    Lyubimova Lyudmila

    2016-01-01

    Full Text Available This paper presents new approaches to solving problems of forecasting the life of heating surface of boilers, based on an analysis of internal structural stresses of the first and second kind that could affect the intragranular and intergranular strength and reliability of the pipeline in continuous operation by making it work without damage by preventing the disclosure of zone cracks.

  20. Worldwide Regulatory Guidance Values Applied to Direct Contact Surface Soil Pesticide Contamination: Part I—Carcinogenic Pesticides

    Directory of Open Access Journals (Sweden)

    Aaron A Jennings

    2017-06-01

    Full Text Available Regulatory agencies worldwide have developed regulatory guidance values (RGVs for nearly 800 pesticides. Analysis of the residential surface soil guidance values applied to the most frequently regulated current-use agriculture, home, and garden pesticides is presented. Part I concentrates on values applied to atrazine, simazine, and trifluralin. These are unique among commonly used pesticides because they are generally considered to be human carcinogens. Their use has been banned in much of the world, but they are commonly used in the United States. Regulatory guidance values applied to these 3 pesticides vary by 8.6, 5.5, and 5.1 orders of magnitude. Risk model coefficient–bounded set uncertainty analysis is applied to help analyze this variability. Cancer risk model uncertainty bounds appear to contain 36.3%, 43.0%, and 49.5% of the RGVs. Most of the remaining values appear to exceed a lifetime cancer incidence risk of 1 × 10 −6 and may not be adequately protective of human health.

  1. Blended 6-Hourly Sea Surface Wind Vectors and Wind Stress on a Global 0.25 Degree Grid (1987-2011)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Blended Global Sea Surface Winds products contain ocean surface wind vectors and wind stress on a global 0.25 degree grid, in multiple time resolutions of...

  2. Piezoresistive Membrane Surface Stress Sensors for Characterization of Breath Samples of Head and Neck Cancer Patients

    Directory of Open Access Journals (Sweden)

    Hans Peter Lang

    2016-07-01

    Full Text Available For many diseases, where a particular organ is affected, chemical by-products can be found in the patient’s exhaled breath. Breath analysis is often done using gas chromatography and mass spectrometry, but interpretation of results is difficult and time-consuming. We performed characterization of patients’ exhaled breath samples by an electronic nose technique based on an array of nanomechanical membrane sensors. Each membrane is coated with a different thin polymer layer. By pumping the exhaled breath into a measurement chamber, volatile organic compounds present in patients’ breath diffuse into the polymer layers and deform the membranes by changes in surface stress. The bending of the membranes is measured piezoresistively and the signals are converted into voltages. The sensor deflection pattern allows one to characterize the condition of the patient. In a clinical pilot study, we investigated breath samples from head and neck cancer patients and healthy control persons. Evaluation using principal component analysis (PCA allowed a clear distinction between the two groups. As head and neck cancer can be completely removed by surgery, the breath of cured patients was investigated after surgery again and the results were similar to those of the healthy control group, indicating that surgery was successful.

  3. Piezoresistive Membrane Surface Stress Sensors for Characterization of Breath Samples of Head and Neck Cancer Patients.

    Science.gov (United States)

    Lang, Hans Peter; Loizeau, Frédéric; Hiou-Feige, Agnès; Rivals, Jean-Paul; Romero, Pedro; Akiyama, Terunobu; Gerber, Christoph; Meyer, Ernst

    2016-07-22

    For many diseases, where a particular organ is affected, chemical by-products can be found in the patient's exhaled breath. Breath analysis is often done using gas chromatography and mass spectrometry, but interpretation of results is difficult and time-consuming. We performed characterization of patients' exhaled breath samples by an electronic nose technique based on an array of nanomechanical membrane sensors. Each membrane is coated with a different thin polymer layer. By pumping the exhaled breath into a measurement chamber, volatile organic compounds present in patients' breath diffuse into the polymer layers and deform the membranes by changes in surface stress. The bending of the membranes is measured piezoresistively and the signals are converted into voltages. The sensor deflection pattern allows one to characterize the condition of the patient. In a clinical pilot study, we investigated breath samples from head and neck cancer patients and healthy control persons. Evaluation using principal component analysis (PCA) allowed a clear distinction between the two groups. As head and neck cancer can be completely removed by surgery, the breath of cured patients was investigated after surgery again and the results were similar to those of the healthy control group, indicating that surgery was successful.

  4. Two Dimensional Array of Piezoresistive Nanomechanical Membrane-Type Surface Stress Sensor (MSS with Improved Sensitivity

    Directory of Open Access Journals (Sweden)

    Nico F. de Rooij

    2012-11-01

    Full Text Available We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor (MSS chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by 3~4 times compared to the first generation MSS chip, resulting in a sensitivity about ~100 times better than a standard cantilever-type sensor and a few times better than optical read-out methods in terms of experimental signal-to-noise ratio. Since the integrated piezoresistive read-out of the MSS can meet practical requirements, such as compactness and not requiring bulky and expensive peripheral devices, the MSS is a promising transducer for nanomechanical sensing in the rapidly growing application fields in medicine, biology, security, and the environment. Specifically, its system compactness due to the integrated piezoresistive sensing makes the MSS concept attractive for the instruments used in mobile applications. In addition, the MSS can operate in opaque liquids, such as blood, where optical read-out techniques cannot be applied.

  5. Effect of laser surface hardening on the microstructure, hardness and residual stresses of austempered ductile iron grades

    Energy Technology Data Exchange (ETDEWEB)

    Soriano, C., E-mail: csoriano@tekniker.es [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain); Leunda, J.; Lambarri, J.; Garcia Navas, V.; Sanz, C. [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain)

    2011-06-01

    A study of the laser surface hardening process of two austempered ductile iron grades, with different austempering treatments has been carried out. Hardening was performed with an infrared continuous wave Nd:YAG laser in cylindrical specimens. The microstructure of the laser hardened samples was investigated using an optical microscope, microhardness profiles were measured and surface and radial residual stresses were studied by an X-ray diffractometer. Similar results were achieved for both materials. A coarse martensite with retained austenite structure was found in the treated area, resulting in a wear resistant effective layer of 0.6 mm to 1 mm with a microhardness between 650 HV and 800 HV. Compressive residual stresses have been found at the hardened area being in agreement with the microhardness and microstructural variations observed. The achieved results point out that the laser surface hardening is a suitable method for improving the mechanical properties of austempered ductile irons.

  6. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Bottoli, Federico; Christiansen, Thomas Lundin; Winther, Grethe

    2016-01-01

    or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa’s in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic...

  7. Large-scale stress factors affecting coral reefs: open ocean sea surface temperature and surface seawater aragonite saturation over the next 400 years

    Science.gov (United States)

    Meissner, K. J.; Lippmann, T.; Sen Gupta, A.

    2012-06-01

    One-third of the world's coral reefs have disappeared over the last 30 years, and a further third is under threat today from various stress factors. The main global stress factors on coral reefs have been identified as changes in sea surface temperature (SST) and changes in surface seawater aragonite saturation (Ωarag). Here, we use a climate model of intermediate complexity, which includes an ocean general circulation model and a fully coupled carbon cycle, in conjunction with present-day observations of inter-annual SST variability to investigate three IPCC representative concentration pathways (RCP 3PD, RCP 4.5, and RCP 8.5), and their impact on the environmental stressors of coral reefs related to open ocean SST and open ocean Ωarag over the next 400 years. Our simulations show that for the RCP 4.5 and 8.5 scenarios, the threshold of 3.3 for zonal and annual mean Ωarag would be crossed in the first half of this century. By year 2030, 66-85% of the reef locations considered in this study would experience severe bleaching events at least once every 10 years. Regardless of the concentration pathway, virtually every reef considered in this study (>97%) would experience severe thermal stress by year 2050. In all our simulations, changes in surface seawater aragonite saturation lead changes in temperatures.

  8. Kd Values for Agricultural and Surface Soils for Use in Hanford Site Farm, Residential, and River Shoreline Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey

    2007-08-01

    This report provides best estimate Kd values and a minimum and maximum range of Kd values to be used for agricultural soils and Columbia River bank sediments that exist today or would exist in the future when portions of the Hanford Site are released for farming, residential, and recreational use after the U. S. Department of Energy (DOE) completes clean up of defense waste on the site. The Kd values should be used to determine the fate and transport rates of contaminants and their availability for plant and animal uptake in selected non-groundwater scenarios included in Hanford Site environmental impact statements, risk assessments and specific facility performance assessments. This report describes scenarios such as a small farm where drilling of a well inadvertently goes through buried waste and brings waste to the surface, allowing the tailings to become available for direct human exposure or incorporation into garden crops and farm animals used for food by the farm family. The Kd values recommended in this report can also be used to calculate sediment-water partitioning factors used to predict plant and animal uptake from interaction with the contaminated soil.

  9. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress

    Science.gov (United States)

    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  10. Atomically flat surface of (0 0 1) textured FePt thin films by residual stress control

    Science.gov (United States)

    Liu, S. H.; Hsiao, S. N.; Chou, C. L.; Chen, S. K.; Lee, H. Y.

    2015-11-01

    Single-layered Fe52Pt48 films with thickness of 10 nm were sputter-deposited on glass substrates. Rapid thermal annealing with different heating rates (10-110 K/s) was applied to transform as-deposited fcc phase into L10 phase and meanwhile to align [0 0 1]-axis of L10 crystal along plane normal direction. Based on X-ray diffractometry using synchrotron radiation source, the texture coefficient of (0 0 1)-plane increases with increasing heating rate from 10 to 40 K/s, which is correlated with perpendicular magnetic anisotropy and in-plane tensile stress analyzed by asymmetric sin2 ψ method. Furthermore, it was revealed by atomic force microscopy that the dewetting process occurred as heating rate was raised up to 80 K/s and higher. The change in the microstructure due to stress relaxation leads to the degradation of (0 0 1) orientation and magnetic properties. Surface roughness is closely related to the in-plane tensile stress. Enhanced perpendicular magnetic anisotropy and atomically flat surface were achieved for the samples annealed at 40 K/s, which may be suitable for further practical applications. This work also suggests a feasible way for surface engineering by controlling internal stress of the FePt without introducing cap layer.

  11. Lower Crustal Flow and Its Relation to the Surface Deformation and Stress Distribution in Western Sichuan Region, China

    Institute of Scientific and Technical Information of China (English)

    Yujiang Li; Lianwang Chen; Pei Tan; Hong Li

    2014-01-01

    The channel flow model was gradually being accepted with the more important multidisci-plinary evidences from geology and geophysics, but how the lower crustal flow influenced the surface de-formation quantitatively was unknown. Here, we develop a three-dimensional viscoelastic model to ex-plore the mechanical relations between the lower crustal flow and the surface deformation in western Si-chuan. Based on numerous tests, our results show that the modeled results fit well with the observed GPS data when the lower crust flows faster than the upper crust about 11 mm/a in the rhombic block, which can be useful to understand the possible mechanism of the surface deformation in western Sichuan. Moreover, taking the Xianshuihe fault as an example, we preliminarily analyze the relation between the active fault and stress field, according to the boundary constraints that deduced from the best model. The results show that the maximum shear stress on the Xianshuihe fault zone is mainly located in the fault terminal, intersections and the bend of the fault geometry, the stress level on the northwestern segment that has the high slip rate is relatively high. Additionally, with the reduction of the Young’s modulus in the fault zone, it’s conducive to generate the greater strain distribution, hence forming the high stress level.

  12. Model-based inverse estimation for active contraction stresses of tongue muscles using 3D surface shape in speech production.

    Science.gov (United States)

    Koike, Narihiko; Ii, Satoshi; Yoshinaga, Tsukasa; Nozaki, Kazunori; Wada, Shigeo

    2017-09-14

    This paper presents a novel inverse estimation approach for the active contraction stresses of tongue muscles during speech. The proposed method is based on variational data assimilation using a mechanical tongue model and 3D tongue surface shapes for speech production. The mechanical tongue model considers nonlinear hyperelasticity, finite deformation, actual geometry from computed tomography (CT) images, and anisotropic active contraction by muscle fibers, the orientations of which are ideally determined using anatomical drawings. The tongue deformation is obtained by solving a stationary force-equilibrium equation using a finite element method. An inverse problem is established to find the combination of muscle contraction stresses that minimizes the Euclidean distance of the tongue surfaces between the mechanical analysis and CT results of speech production, where a signed-distance function represents the tongue surface. Our approach is validated through an ideal numerical example and extended to the real-world case of two Japanese vowels, /ʉ/ and /ɯ/. The results capture the target shape completely and provide an excellent estimation of the active contraction stresses in the ideal case, and exhibit similar tendencies as in previous observations and simulations for the actual vowel cases. The present approach can reveal the relative relationship among the muscle contraction stresses in similar utterances with different tongue shapes, and enables the investigation of the coordination of tongue muscles during speech using only the deformed tongue shape obtained from medical images. This will enhance our understanding of speech motor control. Copyright © 2017. Published by Elsevier Ltd.

  13. Near-nadir microwave specular returns from the sea surface - Altimeter algorithms for wind and wind stress

    Science.gov (United States)

    Wu, Jin

    1992-01-01

    Two approaches have been adopted to construct altimeter wind algorithms: one is based on the mean-square sea surface slope, and the other is based on the Seasat scatterometer wind. Both types of algorithms are critically reviewed with respect to the mechanism governing near-nadir sea returns and the comparison between altimeter and buoy winds. A new algorithm is proposed; it is deduced on the basis of microwave specular reflection and is finely tuned with buoy-measured winds. On the basis of this algorithm and the formula of the wind-stress coefficient, a simple wind-stress algorithm is also proposed.

  14. Influence of Additive Manufactured Scaffold Architecture on the Distribution of Surface Strains and Fluid Flow Shear Stresses and Expected Osteochondral Cell Differentiation

    Science.gov (United States)

    Hendrikson, Wim J.; Deegan, Anthony J.; Yang, Ying; van Blitterswijk, Clemens A.; Verdonschot, Nico; Moroni, Lorenzo; Rouwkema, Jeroen

    2017-01-01

    Scaffolds for regenerative medicine applications should instruct cells with the appropriate signals, including biophysical stimuli such as stress and strain, to form the desired tissue. Apart from that, scaffolds, especially for load-bearing applications, should be capable of providing mechanical stability. Since both scaffold strength and stress–strain distributions throughout the scaffold depend on the scaffold’s internal architecture, it is important to understand how changes in architecture influence these parameters. In this study, four scaffold designs with different architectures were produced using additive manufacturing. The designs varied in fiber orientation, while fiber diameter, spacing, and layer height remained constant. Based on micro-CT (μCT) scans, finite element models (FEMs) were derived for finite element analysis (FEA) and computational fluid dynamics (CFD). FEA of scaffold compression was validated using μCT scan data of compressed scaffolds. Results of the FEA and CFD showed a significant impact of scaffold architecture on fluid shear stress and mechanical strain distribution. The average fluid shear stress ranged from 3.6 mPa for a 0/90 architecture to 6.8 mPa for a 0/90 offset architecture, and the surface shear strain from 0.0096 for a 0/90 offset architecture to 0.0214 for a 0/90 architecture. This subsequently resulted in variations of the predicted cell differentiation stimulus values on the scaffold surface. Fluid shear stress was mainly influenced by pore shape and size, while mechanical strain distribution depended mainly on the presence or absence of supportive columns in the scaffold architecture. Together, these results corroborate that scaffold architecture can be exploited to design scaffolds with regions that guide specific tissue development under compression and perfusion. In conjunction with optimization of stimulation regimes during bioreactor cultures, scaffold architecture optimization can be used to improve

  15. A study of an influence of a fiber arrangement of a laminate ply on the distribution and values of stresses in the multi-layered composite material

    Directory of Open Access Journals (Sweden)

    Herbuś Krzysztof

    2017-01-01

    Full Text Available In the work are presented studies related with the influence of a fiber arrangement of a laminate ply on the distribution and values of stresses in the multi-layered composite material. For this purpose, the characteristics of the three-point bending test, according to the standard PN-EN ISO 7438, of specimens made from the composite material, where a single ply is a composition of epoxy resin and glass fibres, was mapped. The modelling process of the multi-layered composite material and its strength verification was performed in the PLM Siemens NX system. Based on the results of performed numerical studies, the relation between the value of the main angle of an arrangement of fibers in each plies of the laminate, and the distribution and values of stresses, occurring in the examined specimens has been determined.

  16. Effect of copper deficiency and of water stress on the microstructure of tomato leaf surface

    OpenAIRE

    Barbara Dyki; Jan Borowski; Waldemar Kowalczyk

    2013-01-01

    The reaction of tomato plants cv. Tukan F1 to copper deficiency and to water stress was compared. Plants grown in copper deficiency and in conditions of water stress were significantly smaller than controls. They had also lower turgor. The epidermis cells of the upper side leaf in the plants growing in copper deficiency or water stress conditions were smaller than in control plants. However the stomata and trichomes number of leaves plants with copper or water deficiency grown were bigger in ...

  17. Most oxidative stress response in water samples comes from unknown chemicals: the need for effect-based water quality trigger values.

    Science.gov (United States)

    Escher, Beate I; van Daele, Charlotte; Dutt, Mriga; Tang, Janet Y M; Altenburger, Rolf

    2013-07-02

    The induction of adaptive stress response pathways is an early and sensitive indicator of the presence of chemical and non-chemical stressors in cells. An important stress response is the Nrf-2 mediated oxidative stress response pathway where electrophilic chemicals or chemicals that cause the formation of reactive oxygen species initiate the production of antioxidants and metabolic detoxification enzymes. The AREc32 cell line is sensitive to chemicals inducing oxidative stress and has been previously applied for water quality monitoring of organic micropollutants and disinfection byproducts. Here we propose an algorithm for the derivation of effect-based water quality trigger values for this end point that is based on the combined effects of mixtures of regulated chemicals. Mixture experiments agreed with predictions by the mixture toxicity concept of concentration addition. The responses in the AREc32 and the concentrations of 269 individual chemicals were quantified in nine environmental samples, ranging from treated effluent, recycled water, stormwater to drinking water. The effects of the detected chemicals could explain less than 0.1% of the observed induction of the oxidative stress response in the sample, affirming the need to use effect-based trigger values that account for all chemicals present.

  18. Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars

    Science.gov (United States)

    Bocanegra Evans, Humberto; Gorumlu, Serdar; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2016-06-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars.

  19. Optimal estimation of areal values of near-land-surface temperatures for testing global and local spatio-temporal trends

    Science.gov (United States)

    Wang, Hong; Pardo-Igúzquiza, Eulogio; Dowd, Peter A.; Yang, Yongguo

    2017-09-01

    This paper provides a solution to the problem of estimating the mean value of near-land-surface temperature over a relatively large area (here, by way of example, applied to mainland Spain covering an area of around half a million square kilometres) from a limited number of weather stations covering a non-representative (biased) range of altitudes. As evidence mounts for altitude-dependent global warming, this bias is a significant problem when temperatures at high altitudes are under-represented. We correct this bias by using altitude as a secondary variable and using a novel clustering method for identifying geographical regions (clusters) that maximize the correlation between altitude and mean temperature. In addition, the paper provides an improved regression kriging estimator, which is optimally determined by the cluster analysis. The optimal areal values of near-land-surface temperature are used to generate time series of areal temperature averages in order to assess regional changes in temperature trends. The methodology is applied to records of annual mean temperatures over the period 1950-2011 across mainland Spain. The robust non-parametric Theil-Sen method is used to test for temperature trends in the regional temperature time series. Our analysis shows that, over the 62-year period of the study, 78% of mainland Spain has had a statistically significant increase in annual mean temperature.

  20. Surface stress and large-scale self-organization at organic-metal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian

    2009-01-22

    The role of elastic interactions, particularly for the self-organized formation of periodically faceted interfaces, was investigated in this thesis for archetype organic-metal interfaces. The cantilever bending technique was applied to study the change of surface stress upon formation of the interface between 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(111). The main focus of this work was on the investigation of the formation of the long-range ordered, self-organized faceted PTCDA/Ag(10 8 7) interface. Reciprocal space maps of this interface were recorded both by spot profile analysis low energy electron diffraction (SPA-LEED) and low energy electron microscopy (LEEM) in selected area LEED mode. Complementary to the reciprocal data, also microscopic real-space LEEM data were used to characterize the morphology of this interface. Six different facet faces ((111), (532), (743), (954), (13 9 5), and (542)) were observed for the preparation path of molecular adsorption on the substrate kept at 550 K. Facet-sensitive dark-field LEEM localized these facets to grow in homogeneous areas of microscopic extensions. The temperature-dependence of the interface formation was studied in a range between 418 K and 612 K in order to learn more about the kinetics of the process. Additional steeper facets of 27 inclination with respect to the (111) surface were observed in the low temperature regime. Furthermore, using facet-sensitive dark-field LEEM, spatial and size distributions of specific facets were studied for the different temperatures. Moreover, the facet dimensions were statistically analyzed. The total island size of the facets follows an exponential distribution, indicating a random growth mode in absence of any mutual facet interactions. While the length distribution of the facets also follows an exponential distribution, the width distribution is peaked, reflecting the high degree of lateral order. This anisotropy is temperature-dependent and occurs

  1. The value of SPECT in the detection of stress injury to the pars interarticularis in patients with low back pain

    OpenAIRE

    Grant Frederick D; Curtis Christine; Zukotynski Katherine; Micheli Lyle; Treves S Ted

    2010-01-01

    Abstract The medical cost associated with back pain in the United States is considerable and growing. Although the differential diagnosis of back pain is broad, epidemiological studies suggest a correlation between adult and adolescent complaints. Injury of the pars interarticularis is one of the most common identifiable causes of ongoing low back pain in adolescent athletes. It constitutes a spectrum of disease ranging from bone stress to spondylolysis and spondylolisthesis. Bone stress may ...

  2. Allowing for surface preparation in stress corrosion cracking modelling; Prise en compte de l`etat de surface dans la modelisation de la fissuration par corrosion sous contrainte

    Energy Technology Data Exchange (ETDEWEB)

    Berge, P.; Buisine, D. [Electricite de France (EDF), 92 - Clamart (France); Gelpi, A. [FRAMATOME, 92 - Paris-La-Defence (France)

    1997-12-31

    When a 600 alloy component is significantly deformed during installation, by welding, rolling, bending, its stress corrosion cracking in Pressurized Water Nuclear Reactor`s primary coolant, is significantly changed by the initial surface treatment. Therefore, the crack initiated time may be reduced by several orders of magnitude for certain surfaces preparations. Allowing for cold working of the surface, for which modelling is proposed, depends less on the degree of cold work then on the depths of the hardened layers. Honing hardens the metal over depths of about one micron for vessel head penetrations, for example, and has little influence on subsequent behaviour after the part deforms. On the other hand, coarser turning treatment produces cold worked layers which can reach several tens of microns and can very significantly reduce the initiation time compared to fine honing. So evaluation after depths of hardening is vital on test pieces for interpreting laboratory results as well as on service components for estimating their service life. Suppression by mechanical or chemical treatment of these layers, after deformation, seems to be the most appropriate solution for reducing over-stressing connected with surface treatment carried out before deformation. (author). 14 refs.

  3. The predictive value of chronic kidney disease for assessing cardiovascular events under consideration of pretest probability for coronary artery disease in patients who underwent stress myocardial perfusion imaging.

    Science.gov (United States)

    Furuhashi, Tatsuhiko; Moroi, Masao; Joki, Nobuhiko; Hase, Hiroki; Masai, Hirofumi; Kunimasa, Taeko; Fukuda, Hiroshi; Sugi, Kaoru

    2013-02-01

    Pretest probability of coronary artery disease (CAD) facilitates diagnosis and risk stratification of CAD. Stress myocardial perfusion imaging (MPI) and chronic kidney disease (CKD) are established major predictors of cardiovascular events. However, the role of CKD to assess pretest probability of CAD has been unclear. This study evaluates the role of CKD to assess the predictive value of cardiovascular events under consideration of pretest probability in patients who underwent stress MPI. Patients with no history of CAD underwent stress MPI (n = 310; male = 166; age = 70; CKD = 111; low/intermediate/high pretest probability = 17/194/99) and were followed for 24 months. Cardiovascular events included cardiac death and nonfatal acute coronary syndrome. Cardiovascular events occurred in 15 of the 310 patients (4.8 %), but not in those with low pretest probability which included 2 CKD patients. In patients with intermediate to high pretest probability (n = 293), multivariate Cox regression analysis identified only CKD [hazard ratio (HR) = 4.88; P = 0.022) and summed stress score of stress MPI (HR = 1.50; P probability. In patients with intermediate to high pretest probability, CKD and stress MPI are independent predictors of cardiovascular events considering the pretest probability of CAD in patients with no history of CAD. In assessing pretest probability of CAD, CKD might be an important factor for assessing future cardiovascular prognosis.

  4. Demonstration of over core stress measurement from surface using the Sigra IST tool

    CSIR Research Space (South Africa)

    Gray, I

    2003-01-01

    Full Text Available 7 Core Sample Mechanical Properties Page 8 Stress Measurement Results Page 8 Principal and Tectonic Stresses and Tectonic Strains Page 9 Conclusions Page 11 Acknowledgments Page 11 Table 1 Sample Descriptions... Solutions Page 26 Appendix D Directional Survey Information Page 39 Appendix E Photographs of Each Test Core Page 41 4 5 TABLES Table 1- Sample Descriptions and Material...

  5. The value of SPECT in the detection of stress injury to the pars interarticularis in patients with low back pain.

    Science.gov (United States)

    Zukotynski, Katherine; Curtis, Christine; Grant, Frederick D; Micheli, Lyle; Treves, S Ted

    2010-03-03

    The medical cost associated with back pain in the United States is considerable and growing. Although the differential diagnosis of back pain is broad, epidemiological studies suggest a correlation between adult and adolescent complaints. Injury of the pars interarticularis is one of the most common identifiable causes of ongoing low back pain in adolescent athletes. It constitutes a spectrum of disease ranging from bone stress to spondylolysis and spondylolisthesis. Bone stress may be the earliest sign of disease. Repetitive bone stress causes bone remodeling and may result in spondylolysis, a non-displaced fracture of the pars interarticularis. A fracture of the pars interarticularis may ultimately become unstable leading to spondylolisthesis. Results in the literature support the use of bone scintigraphy to diagnose bone stress in patients with suspected spondylolysis. Single photon emission computed tomography (SPECT) provides more contrast than planar bone scintigraphy, increases the sensitivity and improves anatomic localization of skeletal lesions without exposing the patient to additional radiation. It also provides an opportunity for better correlation with other imaging modalities, when necessary. As such, the addition of SPECT to standard planar bone scintigraphy can result in a more accurate diagnosis and a better chance for efficient patient care. It is our expectation that by improving our ability to correctly diagnose bone stress in patients with suspected injury of the posterior elements, the long-term cost of managing this condition will be lowered.

  6. The value of SPECT in the detection of stress injury to the pars interarticularis in patients with low back pain

    Directory of Open Access Journals (Sweden)

    Grant Frederick D

    2010-03-01

    Full Text Available Abstract The medical cost associated with back pain in the United States is considerable and growing. Although the differential diagnosis of back pain is broad, epidemiological studies suggest a correlation between adult and adolescent complaints. Injury of the pars interarticularis is one of the most common identifiable causes of ongoing low back pain in adolescent athletes. It constitutes a spectrum of disease ranging from bone stress to spondylolysis and spondylolisthesis. Bone stress may be the earliest sign of disease. Repetitive bone stress causes bone remodeling and may result in spondylolysis, a non-displaced fracture of the pars interarticularis. A fracture of the pars interarticularis may ultimately become unstable leading to spondylolisthesis. Results in the literature support the use of bone scintigraphy to diagnose bone stress in patients with suspected spondylolysis. Single photon emission computed tomography (SPECT provides more contrast than planar bone scintigraphy, increases the sensitivity and improves anatomic localization of skeletal lesions without exposing the patient to additional radiation. It also provides an opportunity for better correlation with other imaging modalities, when necessary. As such, the addition of SPECT to standard planar bone scintigraphy can result in a more accurate diagnosis and a better chance for efficient patient care. It is our expectation that by improving our ability to correctly diagnose bone stress in patients with suspected injury of the posterior elements, the long-term cost of managing this condition will be lowered.

  7. Heat transfer in a couple stress fluid over a continuous moving surface with internal hat generation and convective boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Tasawar [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics; Iqbal, Zahid [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; Qasim, Muhammad [COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan). Dept. of Mathematics; Aldossary, Omar M. [King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics

    2012-05-15

    This investigation reports the boundary layer flow and heat transfer characteristics in a couple stress fluid flow over a continuos moving surface with a parallel free stream. The effects of heat generation in the presence of convective boundary conditions are also investigated. Series solutions for the velocity and temperature distributions are obtained by the homotopy analysis method (HAM). Convergence of obtained series solutions are analyzed. The results are obtained and discussed through graphs for physical parameters of interest. (orig.)

  8. Interrogation of the microstructure and residual stress of a nickel-base alloy subjected to surface severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, A.L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071 Badajoz (Spain); Tian, J.W. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Villegas, J.C. [Intel Corporation, Chandler, AZ (United States); Shaw, L.L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)], E-mail: Leon.Shaw@Uconn.Edu; Liaw, P.K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States)

    2008-02-15

    A low stacking-fault energy nickel-base, single-phase, face-centered-cubic (fcc) alloy has been subjected to surface severe plastic deformation (S{sup 2}PD) to introduce nano-grains and grain size gradients to the surface region of the alloy. The simultaneous microstructural and stress state changes induced by S{sup 2}PD have been investigated via the X-ray diffraction (XRD) analysis that includes evaluation of annealing and deformation twins, deformation faults, in-plane lattice parameters and elastic strains of the crystal lattice, macroscopic residual in-plane stresses, crystallite sizes, internal strains, dislocation densities, and crystallographic texture as a function of the depth measured from the processed surface. Microstructural changes have also been characterized using optical and electron microscopy in order to corroborate the findings from the XRD analysis. The results from the XRD analysis are in excellent agreement with those derived from the microscopy analysis. This is the first systematic and comprehensive study using XRD to quantify depth-profile changes in a wide range of microstructural features and stress states in a fcc material resulting from the S{sup 2}PD process.

  9. Effect of copper deficiency and of water stress on the microstructure of tomato leaf surface

    Directory of Open Access Journals (Sweden)

    Barbara Dyki

    2013-12-01

    Full Text Available The reaction of tomato plants cv. Tukan F1 to copper deficiency and to water stress was compared. Plants grown in copper deficiency and in conditions of water stress were significantly smaller than controls. They had also lower turgor. The epidermis cells of the upper side leaf in the plants growing in copper deficiency or water stress conditions were smaller than in control plants. However the stomata and trichomes number of leaves plants with copper or water deficiency grown were bigger in comparision with control. The pores of stomata were always larger in leaves of control plants than in other objects.

  10. Quantifying the size-dependent effect of the residual surface stress on the resonant frequencies of silicon nanowires if finite deformation kinematics are considered.

    Science.gov (United States)

    Park, Harold S

    2009-03-18

    There are two major objectives to the present work. The first objective is to demonstrate that, in contrast to predictions from linear surface elastic theory, when nonlinear, finite deformation kinematics are considered, the residual surface stress does impact the resonant frequencies of silicon nanowires. The second objective of this work is to delineate, as a function of nanowire size, the relative contributions of both the residual (strain-independent) and the surface elastic (strain-dependent) parts of the surface stress to the nanowire resonant frequencies. Both goals are accomplished by using the recently developed surface Cauchy-Born model, which accounts for nanoscale surface stresses through a nonlinear, finite deformation continuum mechanics model that leads to the solution of a standard finite element eigenvalue problem for the nanowire resonant frequencies. In addition to demonstrating that the residual surface stress does impact the resonant frequencies of silicon nanowires, we further show that there is a strong size dependence to its effect; in particular, we find that consideration of the residual surface stress alone leads to significant errors in predictions of the nanowire resonant frequency, with an increase in error with decreasing nanowire size. Correspondingly, the strain-dependent part of the surface stress is found to have an increasingly important effect on the resonant frequencies of the nanowires with decreasing nanowire size.

  11. Prognostic Value of Coronary Flow Reserve Obtained on Dobutamine Stress Echocardiography and its Correlation with Target Heart Rate.

    Science.gov (United States)

    Abreu, José Sebastião de; Rocha, Eduardo Arrais; Machado, Isadora Sucupira; Parahyba, Isabelle O; Rocha, Thais Brito; Paes, Fernando José Villar Nogueira; Diogenes, Tereza Cristina Pinheiro; Abreu, Marília Esther Benevides de; Farias, Ana Gardenia Liberato Ponte; Carneiro, Marcia Maria; Paes, José Nogueira

    2017-05-01

    Normal coronary flow velocity reserve (CFVR) (≥ 2) obtained in the left anterior descending coronary artery (LAD) from transthoracic echocardiography is associated with a good prognosis, but there is no study correlating CFVR with submaximal target heart rate (HR). To evaluate the prognostic value of CFVR obtained in the LAD of patients with preserved (>50%) left ventricular ejection fraction (LVEF) who completed a dobutamine stress echocardiography (DSE), considering target HR. Prospective study of patients with preserved LVEF and CFVR obtained in the LAD who completed DSE. In Group I (GI = 31), normal CFVR was obtained before achieving target HR, and, in Group II (GII = 28), after that. Group III (G III=24) reached target HR, but CFVR was abnormal. Death, acute coronary insufficiency, coronary intervention, coronary angiography without further intervention, and hospitalization were considered events. In 28 ± 4 months, there were 18 (21.6%) events: 6% (2/31) in GI, 18% (5/28) in GII, and 46% (11/24) in GIII. There were 4 (4.8%) deaths, 6 (7.2%) coronary interventions and 8 (9.6%) coronary angiographies without further intervention. In event-free survival by regression analysis, GIII had more events than GI (p 50%) e ecocardiograma sob estresse com dobutamina (EED) concluído, considerando a FC alvo submáxima. studo prospectivo de pacientes com FEVE preservada e RVFC obtida na ADA durante EED concluído. No Grupo I (GI=31), a RVFC adequada foi obtida antes de se atingir a FC alvo, e no Grupo II (G II=28), após. O Grupo III (G III=24) atingiu a FC alvo, mas a RVFC foi inadequada. Foram considerados eventos: óbito, insuficiência coronariana aguda, intervenção coronariana, coronariografia sem intervenção subsequente e internamento hospitalar. Em 28 ± 4 meses, ocorreram 18 (21,6%) eventos, sendo 6% (2/31) no GI, 18% (5/28) no GII e 46% (11/24) no GIII. Foram 4 (4,8%) óbitos, 6 (7,2%) intervenções coronarianas e 8 (9,6%) coronariografias sem interven

  12. Low-Stress Silicon Cladding for Surface Finishing Large UVOIR Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase I research, ZeCoat Corporation will develop an affordable, low-stress silicon cladding process which is super-polishable for large UVOIR mirrors. The...

  13. Modelling the Effects of Surface Residual Stresses on Fatigue Behavior of PM Disk Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A finite element based model will be developed and validated to capture the evolution of residual stresses and cold work at machined features of compressor and...

  14. Predictive Value of Urodynamics on Outcome After Midurethral Sling Surgery for Female Stress Urinary Incontinence EDITORIAL COMMENT

    NARCIS (Netherlands)

    Houwert, R. Marijn; Venema, Pieter L.; Aquarius, Annelies E.; Bruinse, Hein W.; Kil, Paul J. M.; Vervest, Harry A. M.

    2009-01-01

    Urodynamic investigation (UDI) is routinely performed before midurethral sling surgery (MUS) for female stress urinary incontinence to detect factors that may adversely affect the surgical outcome or confirm the diagnosis. A recent review, however, concluded that there was insufficient evidence to d

  15. Round robin analysis on stress intensity factor of inner surface cracks in welded stainless steel pipes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)

    2016-12-15

    Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  16. Round Robin Analyses on Stress Intensity Factors of Inner Surface Cracks in Welded Stainless Steel Pipes

    Directory of Open Access Journals (Sweden)

    Chang-Gi Han

    2016-12-01

    Full Text Available Austenitic stainless steels (ASSs are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  17. Nanotopography and Surface Stress Analysis of Ti6Al4V Bioimplant: An Alternative Design for Stability

    Science.gov (United States)

    Patel, Sweetu; Solitro, Giovanni Francesco; Sukotjo, Cortino; Takoudis, Christos; Mathew, Mathew T.; Amirouche, Farid; Shokuhfar, Tolou

    2015-11-01

    The mechanical stability of biomedical Ti6Al4V rods with vertically aligned nanotubes structure formed on their surface has yet to be fully tested during insertion into the bone. The surface of rods impacted during insertion into a bone makes shear contact with bone, generating an interfacial stress. This stress plays an important role in osseointegration and may contribute to loosening between the bone and the implant during surgery. In the current study, the mechanical stability of various Ti6Al4V surfaces, including machined (M), rough (R), machined-anodized (MA), and rough-anodized (RA) surfaces, were tested and fully analyzed during insertion and pullout test into a simulant bone with densities 15 and 20 pounds per cubic foot (pcf). Our initial results from the field emission scanning electron microscopy images taken before and after insertion reveal that titania nanotubes remained stable and maintained their structural integrity during the insertion and pullout Instron test. Furthermore, from the interfacial stress calculation during the insertion, it was observed that compared with nonanodized rods, a higher force was required to insert the anodized rods. The interfacial stress generated during the insertion of anodized rods was 1.03 ± 0.11 MPa for MA and 1.10 ± 0.36 MPa for RA, which is significantly higher ( p anodized rod insertion (i.e., MA = 1.3 ± 0.04 Nm and RA = 1.23 ± 0.24 Nm) was not significantly different than nonanodized rod insertion (i.e., M = 0.9 ± 0.05 Nm and R = 1.04 ± 0.04 Nm) into 15 pcf simulant bone. The high stress during insertion of anodized rods suggests that the nanotubes on the surface can cause gripping and high friction on the radial side, resisting the counter motion of the bone. The latter may play a beneficial role in preventing micromotion between the bone and implant and therefore reducing the chance of fretting/fatigue corrosion.

  18. Negative predictive value of normal adenosine-stress cardiac MRI in the assessment of coronary artery disease and correlation with semiquantitative perfusion analysis.

    Science.gov (United States)

    Pilz, Guenter; Eierle, Susanne; Heer, Tobias; Klos, Markus; Ali, Eman; Scheck, Roland; Wild, Michael; Bernhardt, Peter; Hoefling, Berthold

    2010-09-01

    To prospectively determine the negative predictive value of normal adenosine stress cardiac MR (CMR) in routine patients referred for evaluation of coronary artery disease (CAD), predominantly with intermediate to high pretest risk. Consecutive patients referred for coronary angiography were examined in a 1.5 Tesla whole-body scanner before catheterization. A total of 158 patients with normal CMR on qualitative assessment were included, and semiquantitative perfusion analysis was performed. Significant CAD was regarded as luminal narrowing of >or=70% in coronary angiography. In the 158 study patients, negative predictive value of normal adenosine-stress CMR for significant CAD was 96.2% (for stenosis >or=90%: 98.1%). True-negative and false-negative patients were comparable regarding clinical presentation, risk factors, and CMR findings. Semiquantitative perfusion analysis gave significantly prolonged arrival time index and peak time index in the false-negative group. Using cutoff values >1.8 for arrival time index or >1.2 for peak time index, the CMR negative predictive value increased to 98.7% (for stenosis >or=90%: to 100%). The very high negative predictive value for CAD supports CMR-based decision making for the indication to coronary angiography. Semiquantitative perfusion analysis seems promising to identify the small group of CAD patients not detectable by qualitative CMR assessment.

  19. Joint use of singular value decomposition and Monte-Carlo simulation for estimating uncertainty in surface NMR inversion

    Science.gov (United States)

    Legchenko, Anatoly; Comte, Jean-Christophe; Ofterdinger, Ulrich; Vouillamoz, Jean-Michel; Lawson, Fabrice Messan Amen; Walsh, John

    2017-09-01

    We propose a simple and robust approach for investigating uncertainty in the results of inversion in geophysics. We apply this approach to inversion of Surface Nuclear Magnetic Resonance (SNMR) data, which is also known as Magnetic Resonance Sounding (MRS). Solution of this inverse problem is known to be non-unique. We inverse MRS data using the well-known Tikhonov regularization method, which provides an optimal solution as a trade-off between the stability and accuracy. Then, we perturb this model by random values and compute the fitting error for the perturbed models. The magnitude of these perturbations is limited by the uncertainty estimated with the singular value decomposition (SVD) and taking into account experimental errors. We use 106 perturbed models and show that the large majority of these models, which have all the water content within the variations given by the SVD estimate, do not fit data with an acceptable accuracy. Thus, we may limit the solution space by only the equivalent inverse models that fit data with the accuracy close to that of the initial inverse model. For representing inversion results, we use three equivalent solutions instead of the only one: the ;best; solution given by the regularization or other inversion technic and the extreme variations of this solution corresponding to the equivalent models with the minimum and the maximum volume of water. For demonstrating our approach, we use synthetic data sets and experimental data acquired in the framework of investigation of a hard rock aquifer in the Ireland (County Donegal).

  20. Zoonotic and non-zoonotic diseases in relation to human personality and societal values: support for the parasite-stress model.

    Science.gov (United States)

    Thornhill, Randy; Fincher, Corey L; Murray, Damian R; Schaller, Mark

    2010-04-11

    The parasite-stress model of human sociality proposes that humans' ontogenetic experiences with infectious diseases as well as their evolutionary historical interactions with these diseases exert causal influences on human psychology and social behavior. This model has been supported by cross-national relationships between parasite prevalence and human personality traits, and between parasite prevalence and societal values. Importantly, the parasite-stress model emphasizes the causal role of non-zoonotic parasites (which have the capacity for human-to-human transmission), rather than zoonotic parasites (which do not), but previous studies failed to distinguish between these conceptually distinct categories. The present investigation directly tested the differential predictive effects of zoonotic and non-zoonotic (both human-specific and multihost) parasite prevalence on personality traits and societal values. Supporting the parasite-stress model, cross-national differences in personality traits (unrestricted sexuality, extraversion, openness to experiences) and in societal values (individualism, collectivism, gender equality, democratization) are predicted specifically by non-zoonotic parasite prevalence.

  1. Surface stress effect on the vibration and instability of nanoscale pipes conveying fluid based on a size-dependent Timoshenko beam model

    Science.gov (United States)

    Ansari, R.; Gholami, R.; Norouzzadeh, A.; Darabi, M. A.

    2015-10-01

    Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes. To this end, the nanoscale pipe is modeled as a Timoshenko nanobeam. The equations of motion of the nanoscale pipe are obtained based on Hamilton's principle and the Gurtin-Murdoch continuum elasticity incorporating the surface stress effect. Afterwards, the generalized differential quadrature method is employed to discretize the governing equations and associated boundary conditions. To what extent important parameters such as the thickness, material and surface stress modulus, residual surface stress, surface density, and boundary conditions influence the natural frequency of nanoscale pipes and the critical velocity of fluid is discussed.

  2. Data Service Platform for Sentinel-2 Surface Reflectance and Value-Added Products: System Use and Examples

    Directory of Open Access Journals (Sweden)

    Francesco Vuolo

    2016-11-01

    Full Text Available This technical note presents the first Sentinel-2 data service platform for obtaining atmospherically-corrected images and generating the corresponding value-added products for any land surface on Earth (http://s2.boku.eodc.eu/. Using the European Space Agency’s (ESA Sen2Cor algorithm, the platform processes ESA’s Level-1C top-of-atmosphere reflectance to atmospherically-corrected bottom-of-atmosphere (BoA reflectance (Level-2A. The processing runs on-demand, with a global coverage, on the Earth Observation Data Centre (EODC, which is a public-private collaborative IT infrastructure in Vienna (Austria for archiving, processing, and distributing Earth observation (EO data (http://www.eodc.eu. Using the data service platform, users can submit processing requests and access the results via a user-friendly web page or using a dedicated application programming interface (API. Building on the processed Level-2A data, the platform also creates value-added products with a particular focus on agricultural vegetation monitoring, such as leaf area index (LAI and broadband hemispherical-directional reflectance factor (HDRF. An analysis of the performance of the data service platform, along with processing capacity, is presented. Some preliminary consistency checks of the algorithm implementation are included to demonstrate the expected product quality. In particular, Sentinel-2 data were compared to atmospherically-corrected Landsat-8 data for six test sites achieving a R2 = 0.90 and Root Mean Square Error (RMSE = 0.031. LAI was validated for one test site using ground estimations. Results show a very good agreement (R2 = 0.83 and a RMSE of 0.32 m2/m2 (12% of mean value.

  3. Viscosity of dilute suspensions of rigid bead arrays at low shear: accounting for the variation in hydrodynamic stress over the bead surfaces.

    Science.gov (United States)

    Allison, Stuart A; Pei, Hongxia

    2009-06-11

    In this work, we examine the viscosity of a dilute suspension of irregularly shaped particles at low shear. A particle is modeled as a rigid array of nonoverlapping beads of variable size and geometry. Starting from a boundary element formalism, approximate account is taken of the variation in hydrodynamic stress over the surface of the individual beads. For a touching dimer of two identical beads, the predicted viscosity is lower than the exact value by 5.2%. The methodology is then applied to several other model systems including tetramers of variable conformation and linear strings of touching beads. An analysis is also carried out of the viscosity and translational diffusion of several dilute amino acids and diglycine in water. It is concluded that continuum hydrodynamic modeling with stick boundary conditions is unable to account for the experimental viscosity and diffusion data simultaneously. A model intermediate between "stick" and "slip" could possibly reconcile theory and experiment.

  4. Method of Maintaining the Required Values of Surface Roughness and Prediction of Technological Conditions for Cold Sheet Rolling

    Directory of Open Access Journals (Sweden)

    Valíček J.

    2014-06-01

    Full Text Available The paper is based on results obtained from topography of surfaces of sheets rolled from deep-drawing steel of the type KOHAL grade 697, non-alloy low-carbon structural steel EN 10263-2:2004 and aluminium. The presented results document correctness of the assumption that the rolling force Froll increases with the increasing reduction Δh and the quality of the rolled surface is improved at the simultaneous increasing of strength of rolled sheets and the decreasing of size of structural grains. The experiment was performed on the two-high rolling stand DUO 210 SVa, which enables only non-continuous technology in contrast to the rolling mill with continuous reduction on one sheet in several degrees on rolling trains, in consequence of which the obtained height parameters of the section are in close correlation with the predicted dependence. Contribution of the work consists in the creation of a mathematical model (algorithm for predicting technological parameters of the two-high rolling stand DUO 210 SVa at change of the absolute reduction Δh, for example for a deep-drawing steel of the type KOHAL grade 697 and non-alloy lowcarbon structural steel PN EN 10263-2:2004 and aluminium, and also in the development of a method of calculation applicable to any material being rolled in general, because the authors have found that various materials can be differentiated by a derived analytical criterion IKP. This criterion is a function of ratio between the modulus of elasticity of reference material and that of actually rolled material. The reference material is here deep-drawing steel of the type KOHAL grade 697. Verification was carried out by measuring changes of final surface roughness profile and final strength of rolled sheets of the stated materials in relation to reductions and those were compared with theoretically predicted values. It is possible to identify and predict on the basis of this algorithm an instant state of surface topography in

  5. Method of Maintaining the Required Values of Surface Roughness and Prediction of Technological Conditions for Cold Sheet Rolling

    Science.gov (United States)

    Valíček, J.; Harničárová, M.; Kušnerová, M.; Zavadil, J.; Grznárik, R.

    2014-06-01

    The paper is based on results obtained from topography of surfaces of sheets rolled from deep-drawing steel of the type KOHAL grade 697, non-alloy low-carbon structural steel EN 10263-2:2004 and aluminium. The presented results document correctness of the assumption that the rolling force Froll increases with the increasing reduction Δh and the quality of the rolled surface is improved at the simultaneous increasing of strength of rolled sheets and the decreasing of size of structural grains. The experiment was performed on the two-high rolling stand DUO 210 SVa, which enables only non-continuous technology in contrast to the rolling mill with continuous reduction on one sheet in several degrees on rolling trains, in consequence of which the obtained height parameters of the section are in close correlation with the predicted dependence. Contribution of the work consists in the creation of a mathematical model (algorithm) for predicting technological parameters of the two-high rolling stand DUO 210 SVa at change of the absolute reduction Δh, for example for a deep-drawing steel of the type KOHAL grade 697 and non-alloy lowcarbon structural steel PN EN 10263-2:2004 and aluminium, and also in the development of a method of calculation applicable to any material being rolled in general, because the authors have found that various materials can be differentiated by a derived analytical criterion IKP. This criterion is a function of ratio between the modulus of elasticity of reference material and that of actually rolled material. The reference material is here deep-drawing steel of the type KOHAL grade 697. Verification was carried out by measuring changes of final surface roughness profile and final strength of rolled sheets of the stated materials in relation to reductions and those were compared with theoretically predicted values. It is possible to identify and predict on the basis of this algorithm an instant state of surface topography in respect to variable

  6. Hydrodynamic Study of a Hollow Fiber Membrane System Using Experimental and Numerical Derived Surface Shear Stresses

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Hunze, M.; Nopens, I.

    2012-01-01

    : 0.25 – 0.49 Pa) with an error of less than 5 %; (ii) high shear stresses (i.e. 90th percentile) predictions were much less accurate (model: 0.60 – 1.23 Pa; experimental: 1.04 – 1.90 Pa) with an error up to 38 %. This was attributed to the fact that the CFD model only considers the two-phase flow (50......Computational Fluids Dynamics (CFD) models can be used to gain insight into the shear stresses induced by air sparging on submerged hollow fiber Membrane BioReactor (MBR) systems. It was found that the average range of shear stresses obtained by the CFD model (0.30 – 0.60 Pa) and experimentally (0.......39 – 0.69 Pa) were in good agreement, with an error less that 15 %. Based on comparison of the cumulative frequency distribution of shear stresses from experiments and simulation: (i) moderate shear stresses (i.e. 50th percentile) were found to be accurately predicted (model: 0.24 – 0.45 Pa; experimental...

  7. Hydrodynamic Study of a Hollow Fiber Membrane System Using Experimental and Numerical Derived Surface Shear Stresses

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Hunze, M.; Nopens, I.

    2012-01-01

    Computational Fluids Dynamics (CFD) models can be used to gain insight into the shear stresses induced by air sparging on submerged hollow fiber Membrane BioReactor (MBR) systems. It was found that the average range of shear stresses obtained by the CFD model (0.30 – 0.60 Pa) and experimentally (0.......39 – 0.69 Pa) were in good agreement, with an error less that 15 %. Based on comparison of the cumulative frequency distribution of shear stresses from experiments and simulation: (i) moderate shear stresses (i.e. 50th percentile) were found to be accurately predicted (model: 0.24 – 0.45 Pa; experimental......: 0.25 – 0.49 Pa) with an error of less than 5 %; (ii) high shear stresses (i.e. 90th percentile) predictions were much less accurate (model: 0.60 – 1.23 Pa; experimental: 1.04 – 1.90 Pa) with an error up to 38 %. This was attributed to the fact that the CFD model only considers the two-phase flow (50...

  8. Reflection and transmission at the boundary surface of modified couple stress thermoelastic media

    Directory of Open Access Journals (Sweden)

    Kumar R.

    2016-02-01

    Full Text Available In this paper the reflection and transmission at a plane interface in modified couple stress generalized thermoelastic solid half spaces in the context of Loard-Shulman (LS and Green-Lindsay (GL theories in welded contact are investigated. Amplitude ratios of various reflected and transmitted waves are obtained due to incidence of a set of coupled longitudinal waves and coupled transverse waves. It is found that the amplitude ratios of various reflected and transmitted waves are functions of the angle of incidence, frequency and are affected by the couple stress properties of the media. Some special cases are deduced from the present formulation.

  9. The Coral Reef Temperature Anomaly Database (CoRTAD) - Global, 4 km, Sea Surface Temperature and Related Thermal Stress Metrics for 1985-2005 (NCEI Accession 0044419)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coral Reef Temperature Anomaly Database (CoRTAD) is a collection of sea surface temperature (SST) and related thermal stress metrics, developed specifically for...

  10. The Contribution of Cell Surface Components to the Neutrophil Mechanosensitivity to Shear Stresses

    Directory of Open Access Journals (Sweden)

    Michael L. Akenhead

    2015-08-01

    Full Text Available This review discusses the regulation of neutrophils by fluid shear stress in the context of factors that may govern cell mechanosensitivity and its influence on cell functions. There is substantial evidence that mechanoreceptors located on the peripheral membrane contribute to the ability of shear stress to regulate cell activity. In the case of neutrophils, the formyl peptide receptor (FPR and the CD18 integrins on the cell membrane have been shown to provide neutrophils with the ability to sense shear stresses in their local environment and alter their physiological state, accordingly. This configuration is also found for other types of cells, although they involve different cell-specific mechanoreceptors. Moreover, from an examination of the neutrophil mechanotransducing capacity, it is apparent that cellular mechanosensitivity depends on a number of factors that, if altered, contribute to dysregulation and ultimately pathophysiology. To exemplify this, we first describe the neutrophil responses to shear exposure. We then review two neutrophil mechanoreceptors, specifically FPR and CD18 integrins, which participate in controlling cell activity levels under physiological conditions. Next, we discuss the various factors that may alter neutrophil mechanosensitivity to shear stress and how these may underlie the circulatory pathobiology of two cardiovascular disease states: hypertension and hypercholesterolemia. Based on the material presented, it is conceivable that cell mechanosensitivity is a powerful global metric that permits a more efficient approach to understanding the contribution of mechanobiology to physiology and to disease processes.

  11. Clinical value of the major types of reactions of the body’s stress-regulating systems in ischemic stroke

    Directory of Open Access Journals (Sweden)

    Aleksandr Mikhailovich Dolgov

    2013-01-01

    Full Text Available The time course of changes in the parameters reflecting the status of different components of the body’s regulatory systems was studied in 125patients with hemispheric ischemic stroke via comprehensive evaluation of the hypothalamo-pituitary axes and some endocrine glands. There were three types of reactions of the body’s stress-regulating systems: 1 normergic; 2 hyperergic; 3 disergic, which characterized adaptive and disadaptive reactions in stroke. The changes in the nitroxydergic mechanisms of vascular tone regulation, which constrain the possible involvement of the vascular wall endothelium in the body’s adaptive reactions, progress as the condition becomes severe.

  12. Lubrication of textured surfaces: a general theory for flow and shear stress factors.

    Science.gov (United States)

    Scaraggi, Michele

    2012-08-01

    We report on a mean field theory of textured surface lubrication. We study the fluid flow dynamics occurring at the interface as a function of the texture characteristics, e.g. texture area density, shape and distribution of microstructures, and local slip lengths. The present results may be very important for the investigation of tailored microtextured surfaces for low-friction hydrodynamic applications.

  13. Influence of the hydrostatic stress component on critical surface expansion in forging compound products

    DEFF Research Database (Denmark)

    Vorm, T; Bay, Niels; Wanheim, Tarras

    1974-01-01

    of a superimposed hydrostatic pressure on the critical surface expansion during a forging process. The critical surface expansion appears to decrease with increasing hydrostatic pressure. This may be due to the fact that the close contact between the materials necessary to obtain bonding is created by a micro...

  14. Critical shear stress on the surface of a cuttings bed; Tensao critica de cisalhamento na superficie de um leito de cascalhos

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Luciana Mancor [Universidade Estadual Norte Fluminense (UENF), Macae, RJ (Brazil). Lab. de Engenharia de Petroleo]. E-mail: luciana@lenep.uenf.br; Campos, Wellington [PETROBRAS, S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas]. E-mail: campos@cenpes.petrobras.com.br; Braga, Luiz Carvalho [Centro Federal de Educacao Tecnologica (CEFET), Macae, RJ (Brazil). Unidade de Ensino Descentralizada]. E-mail: luiz@lenep.uenf.br

    2000-07-01

    The cuttings transport during the drilling of highly inclined and horizontal wells is hindered by the creation of a cuttings bed in the annulus. In this work, it is shown that the equilibrium height of this bed can be determined from the shear stress on its surface. This fact enables the formulation of a methodology for evaluating the equilibrium height of the cuttings bed through the introduction of a new concept, that of critical shear stress. This is the shear stress that acts on the bed surface at the imminence of movement of the particles on the bed surface. The use of the methodology requires the determination of the acting shear stress and of the required critical shear stress. The acting shear stress is calculated by means of a computer program that solve the motion differential equations in the annular space; covering the cases of the laminar and turbulent flow regimes. The actuating shear stress is a function of flow rate and of the annular geometry in the presence of a cuttings bed; it is also a function of the physical properties of the fluid. On the other hand, the required critical shear stress is a function of the particles diameters and physical properties of the fluid and particles. A mechanistic model for the critical shear stress is also presented. (author)

  15. The Effect Of Two-Stage Age Hardening Treatment Combined With Shot Peening On Stress Distribution In The Surface Layer Of 7075 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Kaczmarek Ł.

    2015-09-01

    Full Text Available The article present the results of the study on the improvement of mechanical properties of the surface layer of 7075 aluminum alloy via two-stage aging combined with shot peening. The experiments proved that thermo-mechanical treatment may significantly improve hardness and stress distribution in the surface layer. Compressive stresses of 226 MPa±5.5 MPa and hardness of 210±2 HV were obtained for selected samples.

  16. Use of response surface methodology to optimise environmental stress conditions on Penicillium glabrum, a food spoilage mould.

    Science.gov (United States)

    Nevarez, Laurent; Vasseur, Valérie; Debaets, Stella; Barbier, Georges

    2010-01-01

    Fungi are ubiquitous microorganisms often associated with spoilage and biodeterioration of a large variety of foods and feedstuffs. Their growth may be influenced by temporary changes in intrinsic or environmental factors such as temperature, water activity, pH, preservatives, atmosphere composition, all of which may represent potential sources of stress. Molecular-based analyses of their physiological responses to environmental conditions would help to better manage the risk of alteration and potential toxicity of food products. However, before investigating molecular stress responses, appropriate experimental stress conditions must be precisely defined. Penicillium glabrum is a filamentous fungus widely present in the environment and frequently isolated in the food processing industry as a contaminant of numerous products. Using response surface methodology, the present study evaluated the influence of two environmental factors (temperature and pH) on P. glabrum growth to determine 'optimised' environmental stress conditions. For thermal and pH shocks, a large range of conditions was applied by varying factor intensity and exposure time according to a two-factorial central composite design. Temperature and exposure duration varied from 30 to 50 °C and from 10 min to 230 min, respectively. The effects of interaction between both variables were observed on fungal growth. For pH, the duration of exposure, from 10 to 230 min, had no significant effect on fungal growth. Experiments were thus carried out on a range of pH from 0.15 to 12.50 for a single exposure time of 240 min. Based on fungal growth results, a thermal shock of 120 min at 40 °C or a pH shock of 240 min at 1.50 or 9.00 may therefore be useful to investigate stress responses to non-optimal conditions.

  17. FINITE ELEMENT METHOD AS A BASIS FOR THE MODELING OF ROAD SURFACE STRESS-STRAIN STATE

    OpenAIRE

    2011-01-01

    Problem statement. Despite the fact that rigid roads with asphalt concrete pavement widespread,their design and calculation provide for approximate data with some number of hidden factors. Thepresent paper proposes to use finite element method to model stress-strain state of rigid roads withasphalt concrete pavement.Results. The use of the finite element method enables one to construct the precise model ofstress-strain state of road pavement. The calculations performed on the basis of the mod...

  18. Pull-in instability analysis of rectangular nanoplate based on strain gradient theory considering surface stress effects

    Science.gov (United States)

    Mirkalantari, S. Amin; Hashemian, Mohammad; Eftekhari, S. Ali; Toghraie, Davood

    2017-08-01

    In this study, a model is developed based on strain gradient, considering surface stress effect. Then, higher-order nonlinear governing equations and corresponding boundary condition for a hydrostatically and electrostatically actuated rectangular nanoplate are obtained using principle of minimum potential energy. The derived nonlinear differential equations are linearized by step-by-step linearization method, and then the obtained linear equations are discretized by generalized differential quadrature (GDQ) method. The effects of three length scale parameters, boundary conditions, thickness of nanoplate, and surface material properties on pull-in instability behavior are investigated. The obtained results demonstrate that the effects of length scale parameter can influence pull-in instability, and for greater amounts of length scale parameter, higher amounts of voltage are concluded.

  19. A method for canopy water content estimation for highly vegetated surfaces-shortwave infrared perpendicular water stress index

    Institute of Scientific and Technical Information of China (English)

    GHULAM; Abduwasit; LI; Zhao-Liang; QIN; QiMing; TONG; QingXi; WANG; JiHua; KASIMU; Alimujiang; ZHU; Lin

    2007-01-01

    In this paper, a new method for canopy water content (FMC) estimation for highly vegetated surfaces- shortwave infrared perpendicular water stress index (SPSI) is developed using NIR, SWIR wavelengths of Enhanced Thematic Mapper Plus (ETM+) on the basis of spectral features and distribution of surface targets with different water conditions in NIR-SWIR spectral space. The developed method is further explored with radiative transfer simulations using PROSPECT, Lillesaeter, SailH and 6S. It is evident from the results of validation derived from satellite synchronous field measurements that SPSI is highly correlated with FMC, coefficient of determination (R squared) and root mean square error are 0.79 and 26.41%. The paper concludes that SPSI has a potential in vegetation water content estimation in terms of FMC.

  20. A model and experimental study of phosphate uptake kinetics in algae:Considering surface adsorption and P-stress

    Institute of Scientific and Technical Information of China (English)

    Bo Yao; Beidou Xi; Chunming Hu; Shouliang Huo; Jing Su; Hongliang Liu

    2011-01-01

    Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by eutrophication. The co-existence of surface adsorbed and intracellular phosphorus pools indicate that phosphate uptake by phytoplankton is, to some extent, a two-stage kinetic process. However, almost all previous uptake models considered the internal uptake stage only and ignored the possible impact of surface adsorption. In this article, a two-stage kinetic uptake model considering both surface adsorption and P-stress on phosphate uptake by algae was constructed and compared to conventional one-stage models, based on experimental data on short-term uptake kinetics of a green algae S. quadricauda. Results indicated that with suitable parameters, the two-stage uptake model not only fit the experimental data better, but also gave more reasonable and realistic explanations to the phosphate uptake process. The results are meaningful as surface-adsorption of phosphate may affect the uptake process of phosphate and assist in understanding realistic phosphate uptake kinetics in phytoplankton.

  1. Continual Measuring of Local Stress Values on Shell of the Blast Furnace Hearth and of Total Shell Expansion

    Directory of Open Access Journals (Sweden)

    P. Bigoš

    2012-01-01

    Full Text Available This paper deals with installation of strain gauges on the external surface of the blast furnace shell in two rows, whereas there will be defi ned 8 measuring points in every row. The fi nal result is evaluation of data obtained during up to 45 days of the operation. In this papers are commentary and discussions to measured time behaviours. The main purpose of this measuring was investigation of impact of salamander on blast furnace shell expansion after its lay off , cooling and next starting of operation.

  2. Delayed baroclinic response of the Antarctic circumpolar current to surface wind stress

    Institute of Scientific and Technical Information of China (English)

    YANG XiaoYi; HUANG RuiXin; WANG Jia; WANG DongXiao

    2008-01-01

    The Antarctic Circumpolar Current (ACC) responds to the surface windstress via two processes,i.e.,the instant barotropic process and the delayed baroclinic process. This study focuses on the baroclinic instability mechanism in ACC,which was less reported in the literatures. Results show that the strengthening of surface zonal windstress causes the enhanced tilting of the isopycnal surface,leading to more intense baroclinic instability. Simultaneously,the mesoscale eddies resulting from the baroclinic instability facilitate the transformation of mean potential energy to eddy energy,which causes the remarkable decrease of the ACC volume transport with the 2-year lag time. This delayed negative correlation between the ACC transport and the zonal windstress may account for the steadiness of the ACC transport during last two decades.

  3. Delayed baroclinic response of the Antarctic circum-polar current to surface wind stress

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Antarctic Circumpolar Current (ACC) responds to the surface windstress via two processes, i.e., the instant barotropic process and the delayed baroclinic process. This study focuses on the baroclinic instability mechanism in ACC, which was less reported in the literatures. Results show that the strengthening of surface zonal windstress causes the enhanced tilting of the isopycnal surface, leading to more intense baroclinic instability. Simultaneously, the mesoscale eddies resulting from the baro- clinic instability facilitate the transformation of mean potential energy to eddy energy, which causes the remarkable decrease of the ACC volume transport with the 2-year lag time. This delayed negative cor- relation between the ACC transport and the zonal windstress may account for the steadiness of the ACC transport during last two decades.

  4. Altimeter Estimation of Sea Surface Wind Stress for Light to Moderate Winds

    Science.gov (United States)

    Vandemark, Douglas; Edson, James B.; Chapron, Bertrand

    1997-01-01

    Aircraft altimeter and in situ measurements are used to examine relationships between altimeter backscatter and the magnitude of near-surface wind and friction velocities. Comparison of altimeter radar cross section with wind speed is made through the modified Chelton-Wentz algorithm. Improved agreement is found after correcting 10-m winds for both surface current and atmospheric stability. An altimeter friction velocity algorithm is derived based on the wind speed model and an open-ocean drag coefficient. Close agreement between altimeter- and in situ-derived friction velocities is found. For this dataset, quality of the altimeter inversion to surface friction velocity is comparable to that for adjusted winds and clearly better than the inversion to true 10-m wind speed.

  5. Analyses of freshwater stress with a couple ground and surface water model in the Pra Basin, Ghana

    Science.gov (United States)

    Owusu, George; Owusu, Alex B.; Amankwaa, Ebenezer Forkuo; Eshun, Fatima

    2015-04-01

    The optimal management of water resources requires that the collected hydrogeological, meteorological, and spatial data be simulated and analyzed with appropriate models. In this study, a catchment-scale distributed hydrological modeling approach is applied to simulate water stress for the years 2000 and 2050 in a data scarce Pra Basin, Ghana. The model is divided into three parts: The first computes surface and groundwater availability as well as shallow and deep groundwater residence times by using POLFLOW model; the second extends the POLFLOW model with water demand (Domestic, Industrial and Agricultural) model; and the third part involves modeling water stress indices—from the ratio of water demand to water availability—for every part of the basin. On water availability, the model estimated long-term annual Pra river discharge at the outflow point of the basin, Deboase, to be 198 m3/s as against long-term average measurement of 197 m3/s. Moreover, the relationship between simulated discharge and measured discharge at 9 substations in the basin scored Nash-Sutcliffe model efficiency coefficient of 0.98, which indicates that the model estimation is in agreement with the long-term measured discharge. The estimated total water demand significantly increases from 959,049,096 m3/year in 2000 to 3,749,559,019 m3/year in 2050 (p < 0.05). The number of districts experiencing water stress significantly increases (p = 0.00044) from 8 in 2000 to 21 out of 35 by the year 2050. This study will among other things help the stakeholders in water resources management to identify and manage water stress areas in the basin.

  6. Metal accumulation and oxidative stress biomarkers in liver of freshwater fish Carassius auratus following in vivo exposure to waterborne zinc under different pH values.

    Science.gov (United States)

    Qu, Ruijuan; Feng, Mingbao; Wang, Xinghao; Qin, Li; Wang, Chao; Wang, Zunyao; Wang, Liansheng

    2014-05-01

    In this study, laboratory experiments were conducted to investigate the combined effect of zinc and pH on metal accumulation and oxidative stress biomarkers in Carassius auratus. Fish were exposed to 0.1 and 1.0mg Zn/L at three pH values (5.0, 7.25, 9.0) for 3, 12, and 30 d. After each exposure, the contents of three trace elements (Zn, Fe and Cu) were determined in liver. Generally, longer exposure to zinc (12d and 30 d) increased hepatic Zn and Cu deposition, but decreased Fe content. Increasing accumulation of Zn in the tissue was also observed with increasing zinc concentration in the exposure medium. Moreover, hepatic antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), together with the level of glutathione (GSH) were measured to evaluate the oxidative stress status. The decreases in the four measured biochemical parameters after 3d exposure might reflect the failure of the antioxidant defense system in neutralizing the ROS generated during the metabolic process, while the recovery of the antioxidants at days 12 and 30 suggested a possible shift toward a detoxification mechanism. With regard to the influence of pH on zinc toxicity, the general observation was that the living environment became more stressful when the water conditions changed from an acidic state toward a near-neutral or alkaline state.

  7. Final Report: Mechanisms of sputter ripple formation: coupling among energetic ions, surface kinetics, stress and composition

    Energy Technology Data Exchange (ETDEWEB)

    Chason, Eric; Shenoy, Vivek

    2013-01-22

    Self-organized pattern formation enables the creation of nanoscale surface structures over large areas based on fundamental physical processes rather than an applied template. Low energy ion bombardment is one such method that induces the spontaneous formation of a wide variety of interesting morphological features (e.g., sputter ripples and/or quantum dots). This program focused on the processes controlling sputter ripple formation and the kinetics controlling the evolution of surfaces and nanostructures in high flux environments. This was done by using systematic, quantitative experiments to measure ripple formation under a variety of processing conditions coupled with modeling to interpret the results.

  8. The effects of surface decarburization on the failure behaviour of structural components under cyclic stress. Einfluss von Randentkohlungserscheinungen auf das Versagensverhalten schwingend beanspruchter Stahlbauteile

    Energy Technology Data Exchange (ETDEWEB)

    Wittmann, K.; Mueller, H.; Macherauch, E. (Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Werkstoffkunde 1)

    1989-01-01

    For quantitative acquisition of the influence of surface decarburizing phenomena on the failure of construction parts under cyclic stress different surface decarburization stages were generated in the steels 42CrMo4 and 100Cr6. After construction part-specific thermal treatment the generated states of residual stress were then determined and life span-oriented fatigue tests were conducted. The studies showed that already a small decarburization in martensitic material conditions of the steels 42CrMo4 and 100Cr6 led to a reduction of the alternating bending strength. The decrease of alternate strength can be associated with the micro-notch effects caused by the internal oxides formed by surface oxidation and/or the residual tension stress developed during the hardening in sub-surface sample areas. Decarburization degrees of more than 50% cause a noticeable decrease of surface stability, an increase of residual tension stresses close to the surface and as a result a pronounced decrease in the alternating bending strength. Fracture surface investigations with scanning electron microscope showed that partially decarburized and surface-oxidized alternating bending samples create many incipient cracks which will initiate the break. (orig./MM).

  9. Role of Mechanical Stress in Regulating Airway Surface Hydration and Mucus Clearance Rates

    Science.gov (United States)

    Button, Brian; Boucher, Richard C.

    2008-01-01

    Effective clearance of mucus is a critical innate airway defense mechanism, and under appropriate conditions, can be stimulated to enhance clearance of inhaled pathogens. It has become increasingly clear that extracellular nucleotides (ATP and UTP) and nucleosides (adenosine) are important regulators of mucus clearance in the airways as a result of their ability to stimulate fluid secretion, mucus hydration, and cilia beat frequency (CBF). One ubiquitous mechanism to stimulate ATP release is through external mechanical stress. This article addresses the role of physiologically-relevant mechanical forces in the lung and their effects on regulating mucociliary clearance (MCC). The effects of mechanical forces on the stimulating ATP release, fluid secretion, CBF, and MCC are discussed. Also discussed is evidence suggesting that airway hydration and stimulation of MCC by stress-mediated ATP release may play a role in several therapeutic strategies directed at improving mucus clearance in patients with obstructive lung diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). PMID:18585484

  10. Field and material stresses predict observable surface forces in optical and electrostatic manipulation

    Science.gov (United States)

    Kemp, Brandon A.; Sheppard, Cheyenne J.

    2016-09-01

    The momentum of light in media has been one of the most debated topics in physics over the past one hundred years. Originally a theoretical debate over the electrodynamics of moving media, practical applications have emerged over the past few decades due to interest in optical manipulation and nanotechnology. Resolution of the debate identifies a kinetic momentum as the momentum of the fields responsible for center of mass translations and a canonical momentum related to the coupled field and material system. The optical momentum resolution has been considered incomplete because it did not uniquely identify the full stress-energy-momentum (SEM) tensor of the field-kinetic subsystem. A consequence of this partial resolution is that the field-kinetic momentum could be described by three of the leading formulations found in the literature. The Abraham, Einstein-Laub, and Chu SEM tensors share the field-kinetic momentum, but their SEM tensors differ resulting in competing force densities. We can show now that the Abraham and Einstein-Laub formulations are invalid since their SEM tensors are not frame invariant, whereas the Chu SEM tensor satisfies relativistic principles as the field-kinetic formulation. However, a number of reports indicate that the force distribution in matter may not accurately represent experimental observations. In this correspondence, we show that the field-kinetic SEM tensor can be used along with the corresponding material subsystem to accurately predict experimental force and stress distributions. We model experimental examples from optical and static manipulation of particles and fluids.

  11. Concomitant production of lipids and carotenoids in Rhodosporidium toruloides under osmotic stress using response surface methodology

    Directory of Open Access Journals (Sweden)

    Gunjan Singh

    2016-10-01

    Full Text Available As a replacement to existing fossil fuels, biofuels, have proven their worth; however, their widespread use is limited due to inconsistent yields, higher costs and poor productivity. An oleaginous yeast, Rhodosporidium toruloides has been reported to accumulate substantial amounts of lipids (that can be converted to biofuels and therefore, it was selected for study and optimization. Apart from lipids, R. toruloides is also reported to produce carotene that can be used as a therapeutic agent. In this study, the culture medium was statistically modelled and optimized for concomitant production of lipids and carotenoids and for improving and maximizing the productivity of lipids as well as carotenes. The two metabolites were expressed differentially in the growth cycle of this organism. Culture medium components were simultaneously varied at 5 different levels using statistical modelling employing RSM. Osmotic stress was introduced in order to simulate saline conditions and optimize the production process to be used in conditions with high salt contents. In this study, we demonstrate 36.2% (w/v lipid production and 27.2% (w/v carotenoid production, under osmotic stress with high salt concentrations, for the first time.

  12. Environmental Degradation of Materials: Surface Chemistry Related to Stress Corrosion Cracking

    Science.gov (United States)

    Schwarz, J. A.

    1985-01-01

    Parallel experiments have been performed in order to develop a comprehensive model for stress cracking (SCC) in structural materials. The central objective is to determine the relationship between the activity and selectivity of the microstructure of structural materials to their dissolution kinetics and experimentally measured SCC kinetics. Zinc was chosen as a prototype metal system. The SCC behavior of two oriented single-crystal disks of zinc in a chromic oxide/sodium sulfate solution (Palmerton solution) were determined. It was found that: (1) the dissolution rate is strongly (hkil)-dependent and proportional to the exposure time in the aggressive environment; and (2) a specific slip system is selectively active to dissolution under applied stress and this slip line controls crack initiation and propagation. As a precursor to potential microgrvity experiments, electrophoretic mobility measurements of zinc particles were obtained in solutions of sodium sulfate (0.0033 M) with concentrations of dissolved oxygen from 2 to 8 ppm. The equilibrium distribution of exposed oriented planes as well as their correlation will determine the particle mobility.

  13. Environmental Degradation of Materials: Surface Chemistry Related to Stress Corrosion Cracking

    Science.gov (United States)

    Schwarz, J. A.

    1985-01-01

    Parallel experiments have been performed in order to develop a comprehensive model for stress cracking (SCC) in structural materials. The central objective is to determine the relationship between the activity and selectivity of the microstructure of structural materials to their dissolution kinetics and experimentally measured SCC kinetics. Zinc was chosen as a prototype metal system. The SCC behavior of two oriented single-crystal disks of zinc in a chromic oxide/sodium sulfate solution (Palmerton solution) were determined. It was found that: (1) the dissolution rate is strongly (hkil)-dependent and proportional to the exposure time in the aggressive environment; and (2) a specific slip system is selectively active to dissolution under applied stress and this slip line controls crack initiation and propagation. As a precursor to potential microgrvity experiments, electrophoretic mobility measurements of zinc particles were obtained in solutions of sodium sulfate (0.0033 M) with concentrations of dissolved oxygen from 2 to 8 ppm. The equilibrium distribution of exposed oriented planes as well as their correlation will determine the particle mobility.

  14. Sea surface temperature anomalies in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    . Further analysis has shown that the sea surface anomalies are well correlated to the anomalies of air temperature and latent heat flux values; whereas they are least correlated to the anomalies of wind stress and net radiation values, except over...

  15. CHARACTERISTICS OF ADHESION AND PROLIFERATION OF MOUSE NIH/3T3 FIBROBLASTS ON THE POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE FILMS WITH DIFFERENT SURFACE ROUGHNESS VALUES

    Directory of Open Access Journals (Sweden)

    V.А. Surguchenko

    2012-01-01

    Full Text Available Adhesion and proliferation of NIH/3Т3 mouse fibroblasts on the surfaces of bacterial copolymer poly(3-hydroxy- butyrate-co-3-hydroxyvalerate films with different roughness was investigated. Atomic force microscopic analysis showed that surface roughness values of all films were significantly greater (92.0 ± 7.0; 290.8 ± 7.0; 588.8 ± 16.0 nm than that of the cultural plastic control (9.5 ±0.6 nm. It was revealed that adhesion and metabolic activity of the cells decreases with the increase of surface roughness values. NIH/3Т3 mouse fibroblasts attached weakly to the surface of copolymer films and washed away the substrate during rinsing and staining. 

  16. The effect of prolonged immersion of giomer bulk-fill composite resin on the pH value of artificial saliva and resin surface roughness

    Science.gov (United States)

    Ratna, A. A.; Triaminingsih, S.; Eriwati, Y. K.

    2017-08-01

    This study aimed to determine the effect of immersion time on the surface roughness of Giomer Bulk-Fill composite resin and on the pH value of artificial saliva. Sixty-three specimens were divided into nine groups and immersed in artificial saliva with pH values of 7, 5.5, and 4.5 for 1 hour, 24 hours, and 72 hours at 37 °C. The changes in artificial saliva pH were measured using a pH meter and the surface roughness was measured using a surface roughness tester. Longer immersion time increases the pH of artificial saliva and the surface roughness of Giomer Bulk-Fill composite resin.

  17. Finite Element Analysis for Cohesive Soil, Stress and Consolidation Problems Using Bounding Surface Plasticity Theory.

    Science.gov (United States)

    1983-12-01

    Formulation of Soil Plasticity ," Chapter in Soils under Cyclic and Transient Loading, 3. Wiley and Sons, 0. C. Zienkiewiez and G. N. Pande, eds., 1982. 2...and . S. DeNatale, "Numerical ’-’. Implementation of a Bounding Surface Soil Plasticity Model," Proc. of theInt. Symp. on Num. Models in Geomech. , V2

  18. Micro-swimmer dynamics in free-surface turbulence subject to wind stress

    Science.gov (United States)

    Marchioli, Cristian; Lovecchio, Salvatore; Soldati, Alfredo

    2016-11-01

    We examine the effect of wind-induced shear on the orientation and distribution of motile micro-swimmers in free-surface turbulence. Winds blowing above the air-water interface can influence the distribution and productivity of motile organisms via the shear generated just below the surface. Swimmer dynamics depend not only by the advection of the fluid but also by external stimuli like nutrient concentration, light, gravity. Here we focus on gyrotaxis, resulting from the gravitational torque generated by an asymmetric mass distribution within the organism. The combination of such torque with the viscous torque due to shear can re-orient swimmers, reducing their vertical migration and causing entrapment in horizontal fluid layers. Through DNS-based Euler-Lagrangian simulations we investigate the effect of wind-induced shear on the motion of gyrotactic swimmers in turbulent open channel flow. We consider different wind directions and swimmers with different reo-rientation time (reflecting the ability to react to turbulent fluctuations). We show that only stable (high-gyrotaxis) swimmers may reach the surface and form densely concentrated filaments, the topology of which depends on the wind direction. Otherwise swimmers exhibit weaker vertical fluxes and segregation at the surface.

  19. Stress-magnetization properties of a silicon iron single crystal under stress

    Science.gov (United States)

    Saito, Akihiko; Hashimoto, Masaaki; Kawaguchi, Eiji; Murashige, Shinichi

    1996-07-01

    The effects of tensile and compressive stress on magnetization changes in a Si-Fe single crystal with a (110) surface and longitudinal directions declined from the [001] direction were investigated. We found a peculiar magnetization change, namely a reversible magnetization change due to stress consisting of two peak values in a constant magnetic field. The double peak characteristic appears in samples with angle smaller than 55° for compressive stress and with angle larger than 60° for tensile stress.

  20. Effects of the Surface Densities of Glycoclusters on the Determination of Their IC50 and Kd Value Determination by Using a Microarray.

    Science.gov (United States)

    Dupin, Lucie; Zuttion, Francesca; Géhin, Thomas; Meyer, Albert; Phaner-Goutorbe, Magali; Vasseur, Jean-Jacques; Souteyrand, Eliane; Morvan, François; Chevolot, Yann

    2015-11-02

    Pseudomonas aeruginosa (PA) is an opportunistic bacterium involved in 10-30% of nosocomial diseases. It causes severe lung injury to cystic fibrosis patients, often leading to patient death. PA strains are multidrug resistant, thus making the design of new therapeutics a challenge for public health. One promising therapeutic option is to design glycoclusters that target the virulence factor of PA. LecA is a galactose-specific lectin that might be involved in adhesion and biofilm formation by PA. The DNA-directed immobilization (DDI) microarray is a powerful tool for screening and understanding of structure-activity relationships between glycoclusters and lectins. High-throughput and multiplexed analysis of lectin-glycocluster interactions on a DDI microarray allows measurement of IC50 and dissociation constant (Kd ) values with minute amounts of material. In order to study the robustness of the DDI microarray in determination of IC50 and Kd values, the impact of glycocluster surface density was investigated. The data obtained show that measured IC50 values were influenced by glycocluster surface density: as the density of glycoclusters increases, the measured IC50 values increase too. In contrast, the measured Kd values were not affected by glycocluster surface density, provided that the experimental conditions allow interaction between glycocluster and lectin at single-molecule level (no surface cluster effect).

  1. Eddy Current Residual Stress Profiling in Surface-Treated Engine Alloys

    Science.gov (United States)

    2009-06-01

    during this process. This method is inherently destructive since it leaves a deep hole on the surface. Although the accuracy of XRD measurements is quite...SP), laser shock peening (LSP), and low-plasticity burnishing (LPB), significantly improve the fatigue resistance and foreign object damage...and XRD results in low-plasticity burnished Waspaloy of approximately 15% maximum plastic strain. There is a fairly good agreement between the non

  2. Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Ingo [Research Institute for Global Change, JAMSTEC, Yokohama (Japan); University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); Xie, Shang-Ping [University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); University of Hawaii at Manoa, Department of Meteorology, Honolulu, HI (United States); Wittenberg, Andrew T. [NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States); Masumoto, Yukio [Research Institute for Global Change, JAMSTEC, Yokohama (Japan)

    2012-03-15

    Most coupled general circulation models (GCMs) perform poorly in the tropical Atlantic in terms of climatological seasonal cycle and interannual variability. The reasons for this poor performance are investigated in a suite of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) coupled GCM. The experiments show that a significant portion of the equatorial SST biases in the model is due to weaker than observed equatorial easterlies during boreal spring. Due to these weak easterlies, the tilt of the equatorial thermocline is reduced, with shoaling in the west and deepening in the east. The erroneously deep thermocline in the east prevents cold tongue formation in the following season despite vigorous upwelling, thus inhibiting the Bjerknes feedback. It is further shown that the surface wind errors are due, in part, to deficient precipitation over equatorial South America and excessive precipitation over equatorial Africa, which already exist in the uncoupled atmospheric GCM. Additional tests indicate that the precipitation biases are highly sensitive to land surface conditions such as albedo and soil moisture. This suggests that improving the representation of land surface processes in GCMs offers a way of improving their performance in the tropical Atlantic. The weaker than observed equatorial easterlies also contribute remotely, via equatorial and coastal Kelvin waves, to the severe warm SST biases along the southwest African coast. However, the strength of the subtropical anticyclone and along-shore winds also play an important role. (orig.)

  3. Vibration of bioliquid-filled microtubules embedded in cytoplasm including surface effects using modified couple stress theory.

    Science.gov (United States)

    Ghorbanpour Arani, A; Abdollahian, M; Jalaei, M H

    2015-02-21

    This paper aims to investigate vibrational behavior of bioliquid-filled microtubules (MTs) embedded in cytoplasm considering surface effects. The interactions between the MT, considered as an orthotropic beam within the framework of Euler-Bernoulli beam (EBB) and Timoshenko beam (TB) models, and its surrounding elastic media are simulated by Pasternak foundation model. The modified couple stress theory (MCST) is applied so as to consider the small scale effects while motion equations are derived using energy method and Hamilto's principle for both EBB and TB models. Finally, an analytical method is employed to obtain the frequency of a bioliquid-filled MT, and therefore frequency-response curves are plotted to investigate the influences of small scale parameter, mass density of bioliquid, surface layer and surrounding elastic medium graphically. The results indicate that bioliquid and surface layers play a key role on the frequency of MTs and that the frequency of MTs is decreased with increasing of the mass density of the bioliquid. Vibration analysis of MTs is being considered as a vital problem since MTs look like the nervous system of the biological cells and transmit vibrational signals. It should be noted that the results of this work are hoped to be of use in advanced medical applications especially in the forthcoming use of MTs in transporters for bio-nanosensors.

  4. Controlled FCC/on-top binding of H/Pt(111) using surface stress

    Science.gov (United States)

    Shuttleworth, I. G.

    2016-08-01

    The preferred binding site of H/Pt(111) has been shown to be change from the on-top to FCC as the Pt(111) surface goes approximately from a state of compressive to tensile strain. A chemical analysis of the system has shown that for both FCC and on-top bound cases the H ssbnd Pt s and H ssbnd Pt d interactions have a similar importance in determining the preferred binding position. It has been seen that FCC-bound H forms a distinct state below the Pt d-band, whereas the on-top bound H does not.

  5. Recovery and Behaviour of Stressed Escherichia coli O157:H7 Cells on Rocket Leaf Surfaces Inoculated by Different Methods

    Directory of Open Access Journals (Sweden)

    ANAS A. AL-NABULSI

    2016-03-01

    Full Text Available E. coli O157:H7 is an emerging public health concern worldwide because of its low infectious dose and ability to survive under adverse conditions. Tests were conducted to determine the abilityof unstressed E. coli O157:H7 cells or those stressed by acid, cold, salt exposure or starvation to survive on the surfaces of rocket leaves after contamination by three methods (dip, spray or spot inoculation and following storage at 10 or 25ºC. E. coli O157:H7 numbers recovered from rocket leaves contaminated by the different techniques were in the order of dip > spot > spray inoculation.Numbers of stressed E. coli O157:H7 recovered after inoculation by all three methods increased significantly over 7d storage at 10 or 25ºC, while unstressed E. coli O157:H7 only grew following dip inoculation. Exposure to adverse environmental conditions may increase the risk of E. coli O157:H7 survival and spread on leafy green vegetables.

  6. Fast in situ phase and stress analysis during laser surface treatment: a synchrotron x-ray diffraction approach.

    Science.gov (United States)

    Kostov, V; Gibmeier, J; Wilde, F; Staron, P; Rössler, R; Wanner, A

    2012-11-01

    An in situ stress analysis by means of synchrotron x-ray diffraction was carried out during laser surface hardening of steel. A single exposure set-up that based on a special arrangement of two fast silicon strip line detectors was established, allowing for fast stress analysis according to the sin(2)ψ x-ray analysis method. For the in situ experiments a process chamber was designed and manufactured, which is described in detail. First measurements were carried out at the HZG undulator imaging beamline (IBL, beamline P05) at the synchrotron storage ring PETRA III, DESY, Hamburg (Germany). The laser processing was carried out using a 6 kW high power diode laser system. Two different laser optics were compared, a Gaussian optic with a focus spot of ø 3 mm and a homogenizing optic with a rectangular spot dimension of 8 × 8 mm(2). The laser processing was carried out using spot hardening at a heating-/cooling rate of 1000 K/s and was controlled via pyrometric temperature measurement using a control temperature of 1150 °C. The set-up being established during the measuring campaign allowed for this first realization data collection rates of 10Hz. The data evaluation procedure applied enables the separation of thermal from elastic strains and gains unprecedented insight into the laser hardening process.

  7. Influences of stress dilation on shape of failure surface for shallow tunnels

    Institute of Scientific and Technical Information of China (English)

    杨小礼; 王金明

    2008-01-01

    For shallow tunnels of single-lane railway and four-lane road,numerical simulation using finite differential code was conducted.The mechanical behavior of loose rock masses was studied considering the influences of shear dilation on the shape of the failure surface for the shallow tunnels,and the break angles using numerical simulation was compared with those using the Rankine’s analytical solutions and design code.From the comparisons,it is found that the difference between the break angle by numerical simulation and the design code is small when the shear dilation angle is equal to 0,with the maximum relative difference being less than 0.2% in road tunnels.With the dilation angle’s increase,the loose plasticity zone area of surrounding rock reduces obviously,and the break angle increases gradually.When the dilation angle is equal to the internal friction angle,the materials follow associated flow rule,and the numerical solution of the break angle is larger than the analytical solution,with the maximum relative difference being greater than 16.7% in road tunnels.Therefore,associated flow rule leads to overestimating break angle,and the dilation angle has an important influence on the failure surface shape for shallow tunnels in the loose surrounding rocks.

  8. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    Science.gov (United States)

    Bottoli, Federico; Christiansen, Thomas L.; Winther, Grethe; Somers, Marcel A. J.

    2016-08-01

    The present work deals with the evaluation of the residual stress profiles in expanded austenite by applying grazing incidence X-ray diffraction (GI-XRD) combined with successive sublayer removal. Annealed and deformed ( ɛ eq=0.5) samples of stable stainless steel EN 1.4369 were nitrided or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa's in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic deformation in the steel prior to thermochemical treatment has a hardly measurable influence on the nitrogen-rich zone, while it has a measurable effect on the stresses and depth of the carbon-rich zone.

  9. Thermal neutrons' flux near the Earth's surface as an evidence of the crustal stress

    Science.gov (United States)

    Sigaeva, Ekaterina; Nechayev, Oleg; Volodichev, Nikolay; Antonova, Valentina; Kryukov, Sergey; Chubenko, Alexander; Shchepetov, Alexander

    There are some ideas about the Earth’s global seismic activity appearance due to tidal forces. At the same time, the correlations between the big series of the earthquakes and the New and Full Moons and between the New and Full Moons and the increasings of the thermal neutrons’ flux from the Earth’s crust were observed. It is as though there are internal links between these three natural phenomena and the physical reasons for their appearance are the same. The paper presents the results of the ground-based thermal neutrons observations during different time periods characterized with phenomena in the near-Earth space (for instance, the New and Full Moon). Basing on the up-to-date conception of the tidal waves influence on the Earth's crust the authors confirm the role of the Moon in the production of the neutron flux near the Earth's surface.

  10. Relation of gender to physician use of test results and to the prognostic value of stress technetium 99m sestamibi myocardial single-photon emission computed tomography scintigraphy.

    Science.gov (United States)

    Travin, M I; Duca, M D; Kline, G M; Herman, S D; Demus, D D; Heller, G V

    1997-07-01

    We analyzed potential gender differences in the use and prognostic value of stress technetium 99m sestamibi tomography, image results, and cardiac event rates over a period of 15 +/- 8 months in 1226 men and 1151 women. Men had more abnormal tomographic images, but referral for catheterization and revascularization similarly increased in relation to the number of defects. Men and women with abnormal images had similar event rates, 19.6% and 18.2%, respectively, although men more often had myocardial infarction or cardiac death (7.6% vs 4.1 %, p < 0.05), whereas women had an increased likelihood of unstable angina or congestive heart failure (11.5% vs 7.6%, p < 0.05). Normal images predicted a low yearly rate of myocardial infarction or death: 1.7% for men and 0.8% for women. Image findings, particularly defect extent, were independent predictors of events in both groups. Thus, after stress Tc-99m sestamibi single-photon emission computed tomography perfusion imaging, there was no gender bias in referral for invasive procedures, and for both men and women image findings were strongly associated with prognostic outcome.

  11. Inactivation model equations and their associated parameter values obtained under static acid stress conditions cannot be used directly for predicting inactivation under dynamic conditions.

    Science.gov (United States)

    Janssen, M; Verhulst, A; Valdramidis, V; Devlieghere, F; Van Impe, J F; Geeraerd, A H

    2008-11-30

    Organic acids (e.g., lactic acid, acetic acid and citric acid) are popular preservatives. In this study, the Listeria innocua inactivation is investigated under dynamic conditions of pH and undissociated lactic acid ([LaH]). A combined primary (Weibull-type) and secondary model developed for the L. innocua inactivation under static conditions [Janssen, M., Geeraerd, A.H., Cappuyns, A., Garcia-Gonzalez, L., Schockaert, G., Van Houteghem, N., Vereecken, K.M., Debevere, J., Devlieghere, F., Van Impe, J.F., 2007. Individual and combined effects of pH and lactic acid concentration on L. innocua inactivation: development of a predictive model and assessment of experimental variability. Applied and Environmental Microbiology 73(5), 1601-1611] was applied to predict the microbial inactivation under dynamic conditions. Because of its non-autonomous character, two approaches were proposed for the application of the Weibull-type model to dynamic conditions. The results quantitatively indicated that the L. innocua cell population was able to develop an induced acid stress resistance under dynamic conditions of pH and [LaH]. From a modeling point of view, it needs to be stressed that (i) inactivation model equations and associated parameter values, derived under static conditions, may not be suitable for use as such under dynamic conditions, and (ii) non-autonomous dynamic models reveal additional technical intricacies in comparison with autonomous models.

  12. Surface Engineering of Polycrystalline Silicon for Long-term Mechanical Stress Endurance Enhancement in Flexible Low Temperature Poly-Si Thin-Film Transistors.

    Science.gov (United States)

    Chen, Bo-Wei; Chang, Ting-Chang; Hung, Yu-Ju; Huang, Shin-Ping; Chen, Hua-Mao; Liao, Po-Yung; Lin, Yu-Ho; Huang, Hui-Chun; Chiang, Hsiao-Cheng; Yang, Chung-I; Zheng, Yu-Zhe; Chu, Ann-Kuo; Li, Hung-Wei; Tsai, Chih-Hung; Lu, Hsueh-Hsing; Wang, Terry Tai-Jui; Chang, Tsu-Chiang

    2017-02-08

    Surface morphology in polycrystalline silicon (poly-Si) film is an issue regardless of whether conventional excimer laser annealing (ELA) or the newer metal-induced lateral crystallization (MILC) process is used. This paper investigates the stress distribution while undergoing long-term mechanical stress and the influence of stress on electrical characteristics. Our simulated results show that the non-uniform stress in the gate insulator is more pronounced near the polysilicon/gate insulator edge and at the two sides of the polysilicon protrusion. This stress results in defects in the gate insulator and leads to a non-uniform degradation phenomenon, which affects both the performance and reliability in thin-film transistors (TFTs). The degree of degradation is similar regardless of bending axis (channel-length axis, channel-width axis) or bending type (compression, tension), which means that the degradation is dominated by the protrusion effects. Furthermore, by utilizing long-term electrical bias stresses after undergoing long-tern bending stress, it is apparent that the carrier injection is severe in the sub-channel region, which confirms that the influence of protrusions is crucial. To eliminate the influence of surface morphology in poly-Si, three kinds of laser energy density were used during crystallization to control the protrusion height. The device with lowest protrusions demonstrates the smallest degradation after undergoing long-term bending.

  13. Prognostic value of dobutamine stress myocardial perfusion echocardiography in patients with known or suspected coronary artery disease and normal left ventricular function

    Science.gov (United States)

    Mattoso, Angele A. A.; Tsutsui, Jeane M.; Kowatsch, Ingrid; Cruz, Vitória Y. L.; Sbano, João C. N.; Ribeiro, Henrique B.; Kalil Filho, Roberto; Porter, Thomas R.; Mathias, Wilson

    2017-01-01

    Objective We sought to determine the prognostic value of qualitative and quantitative analysis obtained by real-time myocardial perfusion echocardiography (RTMPE) in patients with known or suspected coronary artery disease (CAD). Background Quantification of myocardial blood flow reserve (MBFR) in patients with CAD using RTMPE has been demonstrated to further improve accuracy over the analysis of wall motion (WM) and qualitative analysis of myocardial perfusion (QMP). Methods From March 2003 to December 2008, we prospectively studied 168 patients with normal left ventricular function (LVF) who underwent dobutamine stress RTMPE. The replenishment velocity reserve (β) and MBFR were derived from RTMPE. Acute coronary events were: cardiac death, myocardial infarction and unstable angina with need for urgent coronary revascularization. Results During a median follow-up of 34 months (5 days to 6.9 years), 17 acute coronary events occurred. Abnormal β reserve in ≥2 coronary territories was the only independent predictor of events hazard ratio (HR) = 21, 95% CI = 4.5–99; p<0.001). Both, abnormal β reserve and MBFR added significant incremental value in predicting events over qualitative analysis of WM and MP (χ2 = 6.6 and χ2 = 24.6, respectively; p = 0.001 and χ2 = 6.6 and χ2 = 15.5, respectively; p = 0.012, respectively). When coronary angiographic data was added to the multivariate analysis model, β reserve remained the only predictor of events with HR of 21.0 (95% CI = 4.5–99); p<0.001. Conclusion Quantitative dobutamine stress RTMPE provides incremental prognostic information over clinical variables, qualitative analysis of WM and MP, and coronary angiography in predicting acute coronary events. PMID:28234978

  14. Electrostatic contribution of surface charge residues to the stability of a thermophilic protein: benchmarking experimental and predicted pKa values.

    Directory of Open Access Journals (Sweden)

    Chi-Ho Chan

    Full Text Available Optimization of the surface charges is a promising strategy for increasing thermostability of proteins. Electrostatic contribution of ionizable groups to the protein stability can be estimated from the differences between the pKa values in the folded and unfolded states of a protein. Using this pKa-shift approach, we experimentally measured the electrostatic contribution of all aspartate and glutamate residues to the stability of a thermophilic ribosomal protein L30e from Thermococcus celer. The pKa values in the unfolded state were found to be similar to model compound pKas. The pKa values in both the folded and unfolded states obtained at 298 and 333 K were similar, suggesting that electrostatic contribution of ionizable groups to the protein stability were insensitive to temperature changes. The experimental pKa values for the L30e protein in the folded state were used as a benchmark to test the robustness of pKa prediction by various computational methods such as H++, MCCE, MEAD, pKD, PropKa, and UHBD. Although the predicted pKa values were affected by crystal contacts that may alter the side-chain conformation of surface charged residues, most computational methods performed well, with correlation coefficients between experimental and calculated pKa values ranging from 0.49 to 0.91 (p<0.01. The changes in protein stability derived from the experimental pKa-shift approach correlate well (r = 0.81 with those obtained from stability measurements of charge-to-alanine substituted variants of the L30e protein. Our results demonstrate that the knowledge of the pKa values in the folded state provides sufficient rationale for the redesign of protein surface charges leading to improved protein stability.

  15. Cell-surface signaling in Pseudomonas: stress responses, iron transport, and pathogenicity.

    Science.gov (United States)

    Llamas, María A; Imperi, Francesco; Visca, Paolo; Lamont, Iain L

    2014-07-01

    Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling (CSS) systems, which are tripartite molecular devices that allow Gram-negative bacteria to transduce an extracellular stimulus into a coordinated transcriptional response. Typically, CSS systems are composed of the following: (1) an outer membrane receptor, which senses the extracellular stimulus; (2) a cytoplasmic membrane-spanning protein involved in signal transduction from the periplasm to the cytoplasm; and (3) an extracytoplasmic function (ECF) sigma factor that initiates expression of the stimulus-responsive gene(s). Members of genus Pseudomonas provide a paradigmatic example of how CSS systems contribute to the global control of gene expression. Most CSS systems enable self-regulated uptake of iron via endogenous (pyoverdine) or exogenous (xenosiderophores, heme, and citrate) carriers. Some are also implicated in virulence, biofilm formation, and cell-cell interactions. Incorporating insights from the well-characterized alginate regulatory circuitry, this review will illustrate common themes and variations at the level of structural and functional properties of Pseudomonas CSS systems. Control of the expression and activity of ECF sigma factors are central to gene regulation via CSS, and the variety of intrinsic and extrinsic factors influencing these processes will be discussed.

  16. Design of low surface roughness-low residual stress-high optoelectronic merit a-IZO thin films for flexible OLEDs

    Science.gov (United States)

    Kumar, Naveen; Wilkinson, Taylor M.; Packard, Corinne E.; Kumar, Mukesh

    2016-06-01

    The development of efficient and reliable large-area flexible optoelectronic devices demands low surface roughness-low residual stress-high optoelectronic merit transparent conducting oxide (TCO) thin films. Here, we correlate surface roughness-residual stress-optoelectronic properties of sputtered amorphous indium zinc oxide (a-IZO) thin films using a statistical design of experiment (DOE) approach and find a common growth space to achieve a smooth surface in a stress-free and high optoelectronic merit a-IZO thin film. The sputtering power, growth pressure, oxygen partial pressure, and RF/(RF+DC) are varied in a two-level system with a full factorial design, and results are used to deconvolve the complex growth space, identifying significant control growth parameters and their possible interactions. The surface roughness of a-IZO thin film varies over 0.19 nm to 3.97 nm, which is not in line with the general assumption of low surface roughness in a-IZO thin films. The initial regression model and analysis of variance reveal no single optimum growth sub-space to achieve low surface roughness (≤0.5 nm), low residual stress (-1 to 0 GPa), and industrially acceptable electrical conductivity (>1000 S/cm) for a-IZO thin films. The extrapolation of growth parameters in light of the current results and previous knowledge leads to a new sub-space, resulting in a low residual stress of -0.52±0.04 GPa, a low surface roughness of 0.55±0.03 nm, and moderate electrical conductivity of 1962±3.84 S/cm in a-IZO thin films. These results demonstrate the utility of the DOE approach to multi-parameter optimization, which provides an important tool for the development of flexible TCOs for the next-generation flexible organic light emitting diodes applications.

  17. Design of Low Surface Roughness-Low Residual Stress-High Optoelectronic Merit a-IZO Thin Films for Flexible OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Naveen; Wilkinson, Taylor M.; Packard, Corinne E.; Kumar, Mukesh

    2016-06-14

    The development of efficient and reliable large-area flexible optoelectronic devices demands low surface roughness-low residual stress-high optoelectronic merit transparent conducting oxide (TCO) thin films. Here, we correlate surface roughness-residual stress-optoelectronic properties of sputtered amorphous indium zinc oxide (a-IZO) thin films using a statistical design of experiment (DOE) approach and find a common growth space to achieve a smooth surface in a stress-free and high optoelectronic merit a-IZO thin film. The sputtering power, growth pressure, oxygen partial pressure, and RF/(RF+DC) are varied in a two-level system with a full factorial design, and results are used to deconvolve the complex growth space, identifying significant control growth parameters and their possible interactions. The surface roughness of a-IZO thin film varies over 0.19 nm to 3.97 nm, which is not in line with the general assumption of low surface roughness in a-IZO thin films. The initial regression model and analysis of variance reveal no single optimum growth sub-space to achieve low surface roughness (=0.5 nm), low residual stress (-1 to 0 GPa), and industrially acceptable electrical conductivity (>1000 S/cm) for a-IZO thin films. The extrapolation of growth parameters in light of the current results and previous knowledge leads to a new sub-space, resulting in a low residual stress of -0.52 +/- 0.04 GPa, a low surface roughness of 0.55 +/- 0.03 nm, and moderate electrical conductivity of 1962 +/- 3.84 S/cm in a-IZO thin films. These results demonstrate the utility of the DOE approach to multi-parameter optimization, which provides an important tool for the development of flexible TCOs for the next-generation flexible organic light emitting diodes applications.

  18. Strategy for Ranking the Science Value of the Surface of Asteroid 101955 Bennu for Sample Site Selection for Osiris-REx

    Science.gov (United States)

    Nakamura-Messenger, K.; Connolly, H. C., Jr.; Lauretta, D. S.

    2014-01-01

    OSRIS-REx is NASA's New Frontiers 3 sample return mission that will return at least 60 g of pristine surface material from near-Earth asteroid 101955 Bennu in September 2023. The scientific value of the sample increases enormously with the amount of knowledge captured about the geological context from which the sample is collected. The OSIRIS-REx spacecraft is highly maneuverable and capable of investigating the surface of Bennu at scales down to the sub-cm. The OSIRIS-REx instruments will characterize the overall surface geology including spectral properties, microtexture, and geochemistry of the regolith at the sampling site in exquisite detail for up to 505 days after encountering Bennu in August 2018. The mission requires at the very minimum one acceptable location on the asteroid where a touch-and-go (TAG) sample collection maneuver can be successfully per-formed. Sample site selection requires that the follow-ing maps be produced: Safety, Deliverability, Sampleability, and finally Science Value. If areas on the surface are designated as safe, navigation can fly to them, and they have ingestible regolith, then the scientific value of one site over another will guide site selection.

  19. Improvement of Wetting Tension Values of Battery Foil Surface%电池箔表面润湿张力值的提高

    Institute of Scientific and Technical Information of China (English)

    陈志轩; 刘英超

    2015-01-01

    Measurement method of wetting tension of battery foil surface was introduced, as well as dyne value, liquid dyne, wettability, surface tension, contact angle and so on theoretical knowledge. The effect of rolling oil on surface wetting tension values was analyzed. Experiments show that the surface wetting tension value of the battery foil products can be improved using A70 base oil and about 8% additive proportion.%分析了轧制油对表面润湿张力值的影响,并根据基础油及添加剂比例配置了不同油样,设计了实验,验证不同油样对于产品表面润湿张力值的影响.实验表明,采用A70基础油和8%左右的添加剂比例可以提升电池箔产品的表面润湿张力值.

  20. The Air-Sea Interface and Surface Stress under Tropical Cyclones

    Science.gov (United States)

    Soloviev, Alexander; Lukas, Roger; Donelan, Mark; Ginis, Isaac

    2013-04-01

    of the drag coefficient wind speed dependence around 65 m/s. This minimum may contribute to the rapid intensification of storms to major tropical cyclones. The subsequent slow increase of the drag coefficient with wind above 65 m/s serves as an obstacle for further intensification of tropical cyclones. Such dependence may explain the observed bi-modal distribution of tropical cyclone intensity. Implementation of the new parameterization into operational models is expected to improve predictions of tropical cyclone intensity and the associated wave field. References: Donelan, M. A., B. K. Haus, N. Reul, W. Plant, M. Stiassnie, H. Graber, O. Brown, and E. Saltzman, 2004: On the limiting aerodynamic roughness of the ocean in very strong winds, Farrell, B.F, and P.J. Ioannou, 2008: The stochastic parametric mechanism for growth of wind-driven surface water waves. Journal of Physical Oceanography 38, 862-879. Kelly, R.E., 1965: The stability of an unsteady Kelvin-Helmholtz flow. J. Fluid Mech. 22, 547-560. Koga, M., 1981: Direct production of droplets from breaking wind-waves-Its observation by a multi-colored overlapping exposure technique, Tellus 33, 552-563. Miles, J.W., 1959: On the generation of surface waves by shear flows, part 3. J. Fluid. Mech. 6, 583-598. Soloviev, A.V. and R. Lukas, 2010: Effects of bubbles and sea spray on air-sea exchanges in hurricane conditions. Boundary-Layer Meteorology 136, 365-376. Soloviev, A., A. Fujimura, and S. Matt, 2012: Air-sea interface in hurricane conditions. J. Geophys. Res. 117, C00J34.

  1. Observation of the Effect of the Jue-tone Music to Reduction of Electricity Value on Channel Points Post-stress%角音对应激后经络电流值回复影响的观察

    Institute of Scientific and Technical Information of China (English)

    周萍; 周象贤

    2003-01-01

    Objective:To observe the effect of the Jue - tone music on the stress. Methods:49 students from Shankou middle school were randomly divided into two groups, one group listened to Jue - tone music for ten minute and the other had a rest for ten minute after speed composition, then measured the electricity value on their channel points. Results: The electricity value on their channel points of the group that they listened to Jue - tone music were reduced more than that of the other group even on Shenmen point , Taichong point and Taixi point (P < 0.05). Conclusion: Jue - tone Music can reduce the electricity value on channel points post - stress.

  2. Quantifying Residual Stresses by Means of Thermoelastic Stress Analysis

    Science.gov (United States)

    Gyekenyesi, Andrew L.; Baaklini, George Y.

    2001-01-01

    This study focused on the application of the Thermoelastic Stress Analysis (TSA) technique as a tool for assessing the residual stress state of structures. TSA is based on the fact that materials experience small temperature changes when compressed or expanded. When a structure is cyclically loaded, a surface temperature profile results which correlates to the surface stresses. The cyclic surface temperature is measured with an infrared camera. Traditionally, the amplitude of a TSA signal was theoretically defined to be linearly dependent on the cyclic stress amplitude. Recent studies have established that the temperature response is also dependent on the cyclic mean stress (i.e., the static stress state of the structure). In a previous study by the authors, it was shown that mean stresses significantly influenced the TSA results for titanium- and nickel-based alloys. This study continued the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in-depth analysis was conducted which involved analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point on a structure subjected to a cyclic load can be simultaneously obtained. The experimental results showed good agreement with the theoretical predictions for both the first and second harmonics of the temperature response. As a result, confidence was achieved concerning the ability to simultaneously obtain values for the static stress state as well as the cyclic stress amplitude of structures subjected to cyclic loads using the TSA technique. With continued research, it is now feasible to establish a protocol that would enable the monitoring of residual stresses in structures utilizing TSA.

  3. Influence of osmotic stress on the profile and gene expression of surface layer proteins in Lactobacillus acidophilus ATCC 4356.

    Science.gov (United States)

    Palomino, María Mercedes; Waehner, Pablo M; Fina Martin, Joaquina; Ojeda, Paula; Malone, Lucía; Sánchez Rivas, Carmen; Prado Acosta, Mariano; Allievi, Mariana C; Ruzal, Sandra M

    2016-10-01

    In this work, we studied the role of surface layer (S-layer) proteins in the adaptation of Lactobacillus acidophilus ATCC 4356 to the osmotic stress generated by high salt. The amounts of the predominant and the auxiliary S-layer proteins SlpA and SlpX were strongly influenced by the growth phase and high-salt conditions (0.6 M NaCl). Changes in gene expression were also observed as the mRNAs of the slpA and slpX genes increased related to the growth phase and presence of high salt. A growth stage-dependent modification on the S-layer protein profile in response to NaCl was observed: while in control conditions, the auxiliary SlpX protein represented less than 10 % of the total S-layer protein, in high-salt conditions, it increased to almost 40 % in the stationary phase. The increase in S-layer protein synthesis in the stress condition could be a consequence of or a way to counteract the fragility of the cell wall, since a decrease in the cell wall thickness and envelope components (peptidoglycan layer and lipoteichoic acid content) was observed in L. acidophilus when compared to a non-S-layer-producing species such as Lactobacillus casei. Also, the stationary phase and growth in high-salt medium resulted in increased release of S-layer proteins to the supernatant medium. Overall, these findings suggest that pre-growth in high-salt conditions would result in an advantage for the probiotic nature of L. acidophilus ATCC 4356 as the increased amount and release of the S-layer might be appropriate for its antimicrobial capacity.

  4. Reusing recycled fibers in high-value fiber-reinforced polymer composites: Improving bending strength by surface cleaning

    OpenAIRE

    Shi, Jian; Bao, Limin; Kobayashi, Ryouhei; Kato, Jun; Kemmochi, Kiyoshi

    2012-01-01

    Glass fiber-reinforced polymer (GFRP) composites and carbon fiber-reinforced polymer (CFRP) composites were recycled using superheated steam. Recycled glass fibers (R-GFs) and recycled carbon fibers (R-CFs) were surface treated for reuse as fiber-reinforced polymer (FRP) composites. Treated R-GFs (TR-GFs) and treated R-CFs (TR-CFs) were characterized by scanning electron microscopy (SEM) and remanufactured by vacuum-assisted resin transfer molding (VARTM). Most residual resin impurities were ...

  5. Reusing recycled fibers in high-value fiber-reinforced polymer composites: Improving bending strength by surface cleaning

    OpenAIRE

    Shi, Jian; Bao, Limin; Kobayashi, Ryouhei; Kato, Jun; Kemmochi, Kiyoshi

    2012-01-01

    Glass fiber-reinforced polymer (GFRP) composites and carbon fiber-reinforced polymer (CFRP) composites were recycled using superheated steam. Recycled glass fibers (R-GFs) and recycled carbon fibers (R-CFs) were surface treated for reuse as fiber-reinforced polymer (FRP) composites. Treated R-GFs (TR-GFs) and treated R-CFs (TR-CFs) were characterized by scanning electron microscopy (SEM) and remanufactured by vacuum-assisted resin transfer molding (VARTM). Most residual resin impurities were ...

  6. Determining the values of second-order surface nonlinearities by measurements with wave plates of different retardations.

    Science.gov (United States)

    Valev, Ventsislav K; Foerier, Stijn; Verbiest, Thierry

    2009-06-01

    We measured the second harmonic generation response of a thin film consisting of chiral molecules with four wave plates having different retardation coefficients. By means of the fitting procedure described in a previously reported formalism, we demonstrated that a single set of tensor components of second order surface nonlinearities fits all the data. Our results provide clear experimental evidence for the validity of this method, which can find applications in the studies of chiral structures and achiral anisotropic materials.

  7. First-Principles Surface Stress Calculations and Multiscale Deformation Analysis of a Self-Assembled Monolayer Adsorbed on a Micro-Cantilever

    Directory of Open Access Journals (Sweden)

    Yu-Ching Shih

    2014-04-01

    Full Text Available Micro-cantilever sensors are widely used to detect biomolecules, chemical gases, and ionic species. However, the theoretical descriptions and predictive modeling of these devices are not well developed, and lag behind advances in fabrication and applications. In this paper, we present a novel multiscale simulation framework for nanomechanical sensors. This framework, combining density functional theory (DFT calculations and finite element method (FEM analysis, is capable of analyzing molecular adsorption-induced deformation and stress fields in the sensors from the molecular scale to the device scale. Adsorption of alkanethiolate self-assembled monolayer (SAM on the Au(111 surface of the micro-cantilever sensor is studied in detail to demonstrate the applicability of this framework. DFT calculations are employed to investigate the molecular adsorption-induced surface stress upon the gold surface. The 3D shell elements with initial stresses obtained from the DFT calculations serve as SAM domains in the adsorption layer, while FEM is employed to analyze the deformation and stress of the sensor devices. We find that the micro-cantilever tip deflection has a linear relationship with the coverage of the SAM domains. With full coverage, the tip deflection decreases as the molecular chain length increases. The multiscale simulation framework provides a quantitative analysis of the displacement and stress fields, and can be used to predict the response of nanomechanical sensors subjected to complex molecular adsorption.

  8. Effects of Strengthening Process on Surface Stress of Cylindrical Rollers%强化处理对圆柱滚子表面应力的影响

    Institute of Scientific and Technical Information of China (English)

    董汉杰; 谢华永

    2015-01-01

    圆柱滚子工作表面及次表面的应力状态对轴承的使用寿命和早期剥落有直接影响,为此对圆柱滚子进行了强化处理试验。结果表明:强化处理后,滚子的表面应力和次表面应力均为压应力;与未强化处理的产品相比,强化处理的滚子次表面压应力明显增加;随着强化时间的延长,表面变质层深度有一定的增加。%The stress state of working surface and subsurface for cylindrical rollers has a direct effect on service life and early spalling of bearings.Therefor,the strengthening process test is carried out for cylindrical rollers.The results show that the surface stress and subsurface stress of rollers are compressive stress after strengthening process.The compres-sive stress of subsurface is obviously larger than that before strengthening process.The depth of surface metamorphic layer is certainly increased with the increase of strengthening time.

  9. Effect of Specific Oil Surface Area on the Thermal Stressing of Rapeseed Oil During Heating in an Electric Frying Pan.

    Science.gov (United States)

    Kobyliński, Jakub P; Krygier, Krzysztof; Karlovits, György; Szydłowska-Czerniak, Aleksandra

    The effect of specific oil surface (SOS) during pan frying of rapeseed oil on its thermal stability and antioxidant capacity (AC) was evaluated. Rapeseed oils with different oil layer heights (OLH = 0.5, 1.0, 1.5, 2.0, and 2.5 cm) were heated on an electric frying pan coated with Teflon at 180 ± 10 °C until a selected end point of 25 % total polar compounds (TPC) was reached. The changes of chemical parameters of oil samples such as peroxide value, p-anisidine value, Totox value, free fatty acids, TPC and AC using the 2,2-diphenyl-1-picrylhydrazyl assay were determined. Irrespective of the applied methods, the highest changes in oil with OLH = 0.5 cm were observed. Heating in low OLH also led to the fastest time of TPC formation in rapeseed oil; the 0.5-cm layer reached 25 % TPC in a relatively short time (71.5 min) compared to the highest OLH = 2.5 cm (t = 315.1 min). The SOS and the rate of change in the heated oils decreased with increasing OLH. Crucial effects of SOS on physicochemical oil changes were observed. The present study demonstrated the protective effect of increasing the OLH on the quality of the heated rapeseed oils.

  10. Propagation of Surface Waves in a Homogeneous Layer of Finite Thickness over an Initially Stressed Functionally Graded Magnetic-Electric-Elastic Half-Space

    Directory of Open Access Journals (Sweden)

    Li Li

    2015-03-01

    Full Text Available The propagation behaviour of Love wave in an initially stressed functionally graded magnetic-electric-elastic half-space carrying a homogeneous layer is investigated. The material parameters in the substrate are assumed to vary exponentially along the thickness direction only. The velocity equations of Love wave are derived on the electrically or magnetically open circuit and short circuit boundary conditions, based on the equations of motion of the graded magnetic-electric-elastic mate- rial with the initial stresses and the free traction boundary conditions of surface and the continuous boundary conditions of interface. The dispersive curves are obtained numerically and the influences of the initial stresses and the material gradient index on the dispersive curves are dis- cussed. The investigation provides a basis for the development of new functionally graded magneto-electro-elastic surface wave devices.

  11. Incremental prognostic value of dobutamine-atropine stress{sup 99m}Tc-tetrofosmin myocardial perfusion imaging for predicting outcome in diabetic patients with limited exercise capacity

    Energy Technology Data Exchange (ETDEWEB)

    Pedone, Chiara [Bellaria Hospital, Department of Cardiology, Bologna (Italy); Schinkel, Arend F.L.; Elhendy, Abdou; Domburg, Ron T. van; Biagini, Elena; Simoons, Maarten L. [Erasmus Medical Center, Department of Cardiology, Rotterdam (Netherlands); Valkema, Roelf [Erasmus Medical Center, Department of Nuclear Medicine, Rotterdam (Netherlands); Bax, Jeroen J. [University Medical Center, Department of Cardiology, Leiden (Netherlands); Poldermans, Don [Erasmus Medical Center, Department of Cardiology, Rotterdam (Netherlands); Erasmus Medical Center, Thoraxcenter, Rotterdam (Netherlands)

    2005-09-01

    This study assessed the incremental value of dobutamine stress{sup 99m}Tc-tetrofosmin single-photon emission computed tomography (SPECT) for the prediction of cardiac events in diabetic patients with limited exercise capacity. The study population comprised 125 consecutive diabetic patients (mean age 61{+-}9 years, 61% men) who were unable to perform an exercise test and underwent dobutamine{sup 99m}Tc-tetrofosmin SPECT. Follow-up was successful in 124 (99%) patients. Three patients who underwent early revascularisation (within 60 days) were excluded. End-points during follow-up were cardiac death and non-fatal myocardial infarction. An abnormal scan (with the presence of reversible or fixed perfusion defects) was observed in 76 (63%) patients. During the follow-up (3.4{+-}1.5 years), 36 patients died (19 cardiac deaths) and four patients had non-fatal myocardial infarction. Cardiac death occurred in one of 49 (2%) patients with a normal myocardial perfusion study and in 18 of 75 (24%) patients with an abnormal study (p<0.001). Abnormal scan was incremental to the clinical parameters in predicting cardiac death ({chi}{sup 2}=48 vs 39, p<0.05) and hard cardiac events ({chi}{sup 2}=50 vs 43, p<0.05). Dobutamine stress{sup 99m}Tc-tetrofosmin SPECT provides prognostic information additional to clinical data for the prediction of cardiac death and hard cardiac events in diabetic patients unable to perform an exercise test. (orig.)

  12. The influence of transition metal solutes on the dislocation core structure and values of the Peierls stress and barrier in tungsten.

    Science.gov (United States)

    Samolyuk, G D; Osetsky, Y N; Stoller, R E

    2013-01-16

    Several transition metals were examined to evaluate their potential for improving the ductility of tungsten. The dislocation core structure and Peierls stress and barrier of 1/2 screw dislocations in binary tungsten-transition metal alloys (W(1-x)TM(x)) were investigated using density functional theory calculations. The periodic quadrupole approach was applied to model the structure of the 1/2 dislocation. Alloying with transition metals was modeled using the virtual crystal approximation and the applicability of this approach was assessed by calculating the equilibrium lattice parameter and elastic constants of the tungsten alloys. Reasonable agreement was obtained with experimental data and with results obtained from the conventional supercell approach. Increasing the concentration of a transition metal from the VIIIA group, i.e. the elements in columns headed by Fe, Co and Ni, leads to reduction of the C' elastic constant and increase of the elastic anisotropy A = C(44)/C'. Alloying W with a group VIIIA transition metal changes the structure of the dislocation core from symmetric to asymmetric, similarly to results obtained for W(1-x)Re(x) alloys in the earlier work of Romaner et al (2010 Phys. Rev. Lett. 104 195503). In addition to a change in the core symmetry, the values of the Peierls stress and barrier are reduced. The latter effect could lead to increased ductility in a tungsten-based alloy. Our results demonstrate that alloying with any of the transition metals from the VIIIA group should have a similar effect to alloying with Re.

  13. DNA damage and oxidative stress in human liver cell L-02 caused by surface water extracts during drinking water treatment in a waterworks in China.

    Science.gov (United States)

    Xie, Shao-Hua; Liu, Ai-Lin; Chen, Yan-Yan; Zhang, Li; Zhang, Hui-Juan; Jin, Bang-Xiong; Lu, Wen-Hong; Li, Xiao-Yan; Lu, Wen-Qing

    2010-04-01

    Because of the daily and life-long exposure to disinfection by-products formed during drinking water treatment, potential adverse human health risk of drinking water disinfection is of great concern. Toxicological studies have shown that drinking water treatment increases the genotoxicity of surface water. Drinking water treatment is comprised of different potabilization steps, which greatly influence the levels of genotoxic products in the surface water and thus may alter the toxicity and genotoxicity of surface water. The aim of the present study was to understand the influence of specific steps on toxicity and genotoxicity during the treatment of surface water in a water treatment plant using liquid chlorine as the disinfectant in China. An integrated approach of the comet and oxidative stress assays was used in the study, and the results showed that both the prechlorination and postchlorination steps increased DNA damage and oxidative stress caused by water extracts in human derived L-02 cells while the tube settling and filtration steps had the opposite effect. This research also highlighted the usefulness of an integrated approach of the comet and oxidative stress assays in evaluating the genotoxicity of surface water during drinking water treatment.

  14. The influence of laser-induced nanosecond rise-time stress waves on the microstructure and surface chemical activity of single crystal Cu nanopillars.

    Science.gov (United States)

    Youssef, G; Crum, R; Prikhodko, S V; Seif, D; Po, G; Ghoniem, N; Kodambaka, S; Gupta, V

    2013-02-28

    An apparatus and test procedure for fabrication and loading of single crystal metal nanopillars under extremely high pressures (>1 GPa) and strain rates (>10(7) s(-1)), using laser-generated stress waves, are presented. Single-crystalline Cu pillars (∼1.20 μm in tall and ∼0.45 μm in diameter) prepared via focused ion beam milling of Cu(001) substrates are shock-loaded using this approach with the dilatational stress waves propagating along the [001] axis of the pillars. Transmission electron microscopy observations of shock-loaded pillars show that dislocation density decreases and that their orientation changes with increasing stress wave amplitude, indicative of dislocation motion. The shock-loaded pillars exhibit enhanced chemical reactivity when submerged in oil and isopropyl alcohol solutions, due likely to the exposure of clean surfaces via surface spallation and formation of surface steps and nanoscale facets through dislocation motion to the surface of the pillars, resulting in growth of thin oxide films on the surfaces of the pillars.

  15. Photogrammetrical deformation measurements at structures located in the vicinity of surface mine slopes, and forecasting of expected deformation values

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, O. (Ingenieurschule fuer Geodaesie und Kartographie, Dresden (German Democratic Republic))

    1990-02-01

    Discusses measurement of equipment stability in brown coal surface mines. A long conveyor belt system installed parallel to the spoil bank slope and a spoil belt conveyor bridge were surveyed for movements of position. Photogrammetrical measuring instrument was the UMK 10/1318 unit of Carl Zeiss Jena; for data analysis the Stecometer G and the TEBIT program systems were used. Measurement results are provided. Forecasting possible future movement of belt conveyor supports was further carried out using a mathematical collocation model and the empirical Moeser auto-covariance function of the bell shaped cosinus type. Results of mathematical forecasting are compared to repeated measurements carried out after 6 months, proving suitability of the mathematical method. 3 refs.

  16. Vaspin is an adipokine ameliorating ER stress in obesity as a ligand for cell-surface GRP78/MTJ-1 complex.

    Science.gov (United States)

    Nakatsuka, Atsuko; Wada, Jun; Iseda, Izumi; Teshigawara, Sanae; Higashio, Kanji; Murakami, Kazutoshi; Kanzaki, Motoko; Inoue, Kentaro; Terami, Takahiro; Katayama, Akihiro; Hida, Kazuyuki; Eguchi, Jun; Horiguchi, Chikage Sato; Ogawa, Daisuke; Matsuki, Yasushi; Hiramatsu, Ryuji; Yagita, Hideo; Kakuta, Shigeru; Iwakura, Yoichiro; Makino, Hirofumi

    2012-11-01

    It is unknown whether adipokines derived from adipose tissues modulate endoplasmic reticulum (ER) stress induced in obesity. Here, we show that visceral adipose tissue-derived serine protease inhibitor (vaspin) binds to cell-surface 78-kDa glucose-regulated protein (GRP78), which is recruited from ER to plasma membrane under ER stress. Vaspin transgenic mice were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis, while vaspin-deficient mice developed glucose intolerance associated with upregulation of ER stress markers. With tandem affinity tag purification using HepG2 cells, we identified GRP78 as an interacting molecule. The complex formation of vaspin, GRP78, and murine tumor cell DnaJ-like protein 1 (MTJ-1) (DnaJ homolog, subfamily C, member 1) on plasma membrane was confirmed by cell-surface labeling with biotin and immunoprecipitation in liver tissues and H-4-II-E-C3 cells. The addition of recombinant human vaspin in the cultured H-4-II-E-C3 cells also increased the phosphorylation of Akt and AMP-activated protein kinase (AMPK) in a dose-dependent manner, and anti-GRP78 antibodies completely abrogated the vaspin-induced upregulation of pAkt and pAMPK. Vaspin is a novel ligand for cell-surface GRP78/MTJ-1 complex, and its subsequent signals exert beneficial effects on ER stress-induced metabolic dysfunctions.

  17. Lassen's equation is a good approximation of permeability-surface model: new α values for ⁹⁹mTc-HMPAO and ⁹⁹mTc-ECD.

    Science.gov (United States)

    Kameyama, Masashi

    2014-07-01

    Brain perfusion tracers like [(99m)Tc] d,l-hexamethyl-propyeneamine oxime ((99m)Tc-HMPAO) and [(99m)Tc] ethyl-cysteinate dimer ((99m)Tc-ECD) underestimate regional cerebral blood flow (rCBF) at high flow values. To improve linearity between tracer accumulation and rCBF, two different models have been proposed. One is Lassen's correction algorithm for back-diffusion of tracer, and the other is based on the permeability-surface (PS) model for correction of low first-pass extraction. Although both these models have the same goal, they have completely different forms of equation. It was demonstrated that mathematical approximation of the PS model equation leads to Lassen's equation. In this process, the relationship between PS, CBF values and Lassen's parameter was acquired, and how to correct both the back-diffusion and low first-pass extraction was also demonstrated. A computer simulation confirmed that the two models provided similar consequences when the parameter value is chosen according to the relationship found. Lassen's equation can be used to correct not only back-diffusion but also low first-pass extraction. To perform overall correction, the parameter value we have been using for decades may be too weak. I estimated that the parameter value for overall correction of HMPAO would be around 0.5, and that of ECD would be around 0.65.

  18. Future trend of extreme value distributions of wintertime surface air temperatures over Korea and the associated physical changes

    Science.gov (United States)

    Kim, Kwang-Yul; Kim, Ji-Won; Kim, Maeng-Ki; Cho, Chun-Ho

    2013-11-01

    Daily winter temperatures in Korea have been analyzed via CSEOF analysis. Then, each PC time series was detrended and was fitted to an AR (autoregressive) model. Based on the identified AR model, an artificial time series of arbitrary length can be generated by using an arbitrary white-noise time series. In this way, one hundred new sets of PC time series were generated over the period of 1973-2058. Then, the trend for each PC time series was added back to the artificial PC time series extending the trend until 2058. Ultimately, artificial daily winter temperatures in Korea have been constructed by using the artificial PC time series and the original loading vectors derived from the observational data. The 100 new data sets have been investigated in order to understand the winter temperature variability 50 years into the future. Regression analysis in CSEOF space shows that temperature increase in Korea is associated with increased 850-hPa air temperature over most of the Asian domain (97°-153°E × 22°-73°N) and increased 850-hPa geopotential height in the southern part of the domain. As a result, southerly and southeasterly wind anomalies develop carrying positive temperature anomalies northward and northwestward. Both the 200-hPa air temperature and geopotential height changes indicate that there will be fairly significant northward shift of the jet stream in future. The standard deviation of the 200-hPa potential vorticity increases implying that shortwave trough and henceforth baroclinic instability will increase in future. Finally, GEV (Generalized Extreme Value) distribution and GPD (Generalized Pareto distribution) distribution have been compared between the observational records and the future records of the same length. The extreme value distributions based on the synthetic datasets show that warm extreme events will be more extreme in future and cold extreme events, on the other hand, will be less extreme. This study provides an estimate of future

  19. The Measurement of the Surface Residual Stresses Induced by Turning in TB2 Parts and the Deformation Prediction Based on FEM%TB2零件表面加工应力的测量及其有限元变形预测∗

    Institute of Scientific and Technical Information of China (English)

    王毅

    2015-01-01

    When TB2 parts have been machined, there will be high residual stresses induced by machining in the surface layers, the surface residual stresses were calculated based on the changing strains when remo-ving the material layer by layer. As to predict the deformations of the parts caused by the surface residual stresses, the residual stresses values changing along the depth direction should be loaded to the FEM model, and the part is cylinder, the stress value in each element is different, a programing method has been presen-ted in this paper. The stress value of each element can be determined based on the coordinates of the nodes, and the stress values of all the elements can be calculated out. The stress file calculated was loaded to the model, with FEM calculation, the deformation of the part caused by surface residual stresses was calculated at last.%在对TB2零件车削加工后,被加工面会有一层加工引起的内应力层,通过对加工进行逐层腐蚀剥层,并用应变片测量此过程中零件内壁应变的变化,最终得到了其加工表面随深度变化的内应力值。为计算此表面内应力对于零件变形的影响,将测得的随深度变化的内应力施加给有限元模型进行计算。由于零件是圆柱形,因此模型中的不同的网格单元所施加内应力均不一样,编程的方法,根据节点的坐标计算网格单元的应力,最终算得的应力文件中包括每个网格单元的所要施加的不同的应力值,将计算结果通过文件导入的方法施加给有限元软件,通过有限元的计算,最终得到了零件因表面内应力而引起的变形。

  20. Optimization on hardness and internal stress of micro-electroformed NiCo/nano-Al2O3 composites with the constraint of low surface roughness

    Science.gov (United States)

    Hung, Shih-Yu

    2009-01-01

    In this paper, Ni-Co/nano-Al2O3 composite electroforming was used to make the metallic micro-mold for a microlens array. The microstructures require higher hardness to improve the wear resistance and lifetime. Nano-Al2O3 was applied to strengthen the Ni-Co matrix by a new micro-electroforming technique. The hardness and internal stress of Ni-Co/nano-Al2O3 composite deposit were investigated. The results showed that the hardness increased with the increasing Al2O3 content, but at the cost of deformation. Increasing the Al2O3 content in the composite was not always beneficial to the electroformed mold for microlens array fabrication. This work will concentrate on the relationship between important mechanical properties and electrolyte parameters of Ni-Co/nano-Al2O3 composite electroforming. Electrolyte parameters such as Al2O3 content, Al2O3 particle diameter, Co content, stress reducer and current density will be examined with respect to internal stress and hardness. In the present study, low stress and high hardness electroforming with the constraint of low surface roughness is carried out using SNAOA algorithm to reduce internal stress and increase service life of micro-mold during the forming process. The results show that the internal stress and the RMS roughness are only 0.54 MPa and 4.8 nm, respectively, for the optimal electrolyte parameters combination of SNAOA design.

  1. The predictive value of post-traumatic stress disorder symptoms for quality of life: a longitudinal study of physically injured victims of non-domestic violence

    Directory of Open Access Journals (Sweden)

    Eilertsen Dag

    2007-05-01

    Full Text Available Abstract Background Little is known about longitudinal associations between post-traumatic stress disorder (PTSD and quality of life (QoL after exposure to violence. The aims of the current study were to examine quality of life (QoL and the predictive value of post-traumatic stress disorder (PTSD for QoL in victims of non-domestic violence over a period of 12 months. Methods A single-group (n = 70 longitudinal design with three repeated measures over a period of 12 months were used. Posttraumatic psychological symptoms were assessed by using the Impact of Event Scale, a 15-item self-rating questionnaire comprising two subscales (intrusion and avoidance as a screening instrument for PTSD. The questionnaire WHOQOL-Bref was used to assess QoL. The WHOQOL-BREF instrument comprises 26 items, which measure the following broad domains: physical health, psychological health, social relationships, and environment. Results of the analysis were summarized by fitting Structural Equation Modelling (SEM. Results For each category of PTSD (probable cases, risk level cases and no cases, the mean levels of the WHOQOL-Bref subscales (the four domains and the two single items were stable across time of assessment. Individuals who scored as probable PTSD or as risk level cases had significantly lower scores on the QoL domains such as physical health, psychological health, social relationships and environmental than those without PTSD symptoms. In addition, the two items examining perception of overall quality of life and perception of overall health in WHOQOL showed the same results according to PTSD symptoms such as QoL domains. PTSD symptoms predicted lower QoL at all three assessments. Similarly PTSD symptoms at T1 predicted lower QoL at T2 and PTSD symptoms at T2 predicted lower QoL at T3. Conclusion The presence of PTSD symptoms predicted lower QoL, both from an acute and prolonged perspective, in victims of non-domestic violence. Focusing on the individual

  2. The predictive value of post-traumatic stress disorder symptoms for quality of life: a longitudinal study of physically injured victims of non-domestic violence.

    Science.gov (United States)

    Johansen, Venke A; Wahl, Astrid K; Eilertsen, Dag Erik; Weisaeth, Lars; Hanestad, Berit R

    2007-05-21

    Little is known about longitudinal associations between post-traumatic stress disorder (PTSD) and quality of life (QoL) after exposure to violence. The aims of the current study were to examine quality of life (QoL) and the predictive value of post-traumatic stress disorder (PTSD) for QoL in victims of non-domestic violence over a period of 12 months. A single-group (n = 70) longitudinal design with three repeated measures over a period of 12 months were used. Posttraumatic psychological symptoms were assessed by using the Impact of Event Scale, a 15-item self-rating questionnaire comprising two subscales (intrusion and avoidance) as a screening instrument for PTSD. The questionnaire WHOQOL-Bref was used to assess QoL. The WHOQOL-BREF instrument comprises 26 items, which measure the following broad domains: physical health, psychological health, social relationships, and environment. Results of the analysis were summarized by fitting Structural Equation Modelling (SEM). For each category of PTSD (probable cases, risk level cases and no cases), the mean levels of the WHOQOL-Bref subscales (the four domains and the two single items) were stable across time of assessment. Individuals who scored as probable PTSD or as risk level cases had significantly lower scores on the QoL domains such as physical health, psychological health, social relationships and environmental than those without PTSD symptoms. In addition, the two items examining perception of overall quality of life and perception of overall health in WHOQOL showed the same results according to PTSD symptoms such as QoL domains. PTSD symptoms predicted lower QoL at all three assessments. Similarly PTSD symptoms at T1 predicted lower QoL at T2 and PTSD symptoms at T2 predicted lower QoL at T3. The presence of PTSD symptoms predicted lower QoL, both from an acute and prolonged perspective, in victims of non-domestic violence. Focusing on the individual's perception of his/her QoL in addition to the illness may

  3. Analysis of the probabilistic characteristics of the dynamic stress of the highspeed railway subgrade surface%高速铁路路基面动应力概率特性研究

    Institute of Scientific and Technical Information of China (English)

    蒋武军

    2016-01-01

    路基动应力特性在高铁路基设计中非常重要,因此对其进行研究具有一定的意义.通过列车-轨道-路基三维有限元数值方法,计算得到了在京津城际轨道不平顺谱下路基面横向各位置处的动应力.利用概率统计理论,统计得到了3种列车速度下路基面横向各位置处动应力的均值和变异系数;并通过对路基面中心位置处动应力计算结果进行统计分析得到了京津城际轨道不平顺谱下路基动应力的最优概率分布模型.结果表明,在京津城际轨道不平顺谱下,路基面动应力均值沿横向呈现“M”型分布,变异系数沿横向逐渐减小.列车速度对路基动应力均值及变异系数具有一定的放大效应,且路基动应力沿纵向近似服从对数正态分布.%This paper intends to provide its analysis of the probabilistic characteristic features of the dynamic stress of the highspeed railway subgrade surface of Beijing-Tianjin inter-city communal railway in the broadwise direction of 6 nodes and in the longitudinal direction of 321 nodes of the subgrade surface under the track irregularity spectrum.According to the vehicle-tracksubgrade dimensional finite element model,there can be found three typical high-speed railway driving speeds,known as 150km/h,250 km/h and 350 km/h.However,based on the reliability theory and the probability statistics theory,the mean value and coefficients of the variations(COVs) of the dynamic stress of subgrade in the said direction can be gained by calculating the dynamic stress of the subgrade in the aforementioned situations.And,finally,we have worked out the mean values and the coefficient of variations (COVs) of the dynamic stress of the subgrade in the broadwise direction of the subgrade surface through comparison of the probability distribution of the dynamic stress of the subgrade in the central position of subgrade surface and the histogram of the data predicted of log-normal distribution

  4. Development of a novel non-contact inspection technique to detect micro cracks under the surface of a glass substrate by thermal stress-induced light scattering method

    Science.gov (United States)

    Sakata, Yoshitaro; Terasaki, Nao; Nonaka, Kazuhiro

    2017-05-01

    Fine polishing techniques, such as a chemical mechanical polishing treatment, are important techniques in glass substrate manufacturing. However, these techniques may cause micro cracks under the surface of glass substrates because they used mechanical friction. A stress-induced light scattering method (SILSM), which was combined with light scattering method and mechanical stress effects, was proposed for inspecting surfaces to detect polishing-induced micro cracks. However, in the conventional SILSM, samples need to be loaded with physical contact, and the loading point is invisible in transparent materials. Here, we introduced a novel non-contact SILSM using a heating device. A glass substrate was heated first, and then the light scattering intensity of micro cracks was detected by a cooled charge-couple device camera during the natural cooling process. Results clearly showed during the decreasing surface temperature of a glass substrate, appropriate thermal stress is generated for detecting micro cracks by using the SILSM and light scattering intensity from micro cracks changes. We confirmed that non-contact thermal SILSM (T-SILSM) can detect micro cracks under the surface of transparent materials.

  5. Treatment of electronic waste to recover metal values using thermal plasma coupled with acid leaching--a response surface modeling approach.

    Science.gov (United States)

    Rath, Swagat S; Nayak, Pradeep; Mukherjee, P S; Roy Chaudhury, G; Mishra, B K

    2012-03-01

    The global crisis of the hazardous electronic waste (E-waste) is on the rise due to increasing usage and disposal of electronic devices. A process was developed to treat E-waste in an environmentally benign process. The process consisted of thermal plasma treatment followed by recovery of metal values through mineral acid leaching. In the thermal process, the E-waste was melted to recover the metal values as a metallic mixture. The metallic mixture was subjected to acid leaching in presence of depolarizer. The leached liquor mainly contained copper as the other elements like Al and Fe were mostly in alloy form as per the XRD and phase diagram studies. Response surface model was used to optimize the conditions for leaching. More than 90% leaching efficiency at room temperature was observed for Cu, Ni and Co with HCl as the solvent, whereas Fe and Al showed less than 40% efficiency.

  6. Coastal sea-surface temperature anomalies during the 2014-2016 northeast Pacific marine heat wave: regional variability, timing, and relation to wind stress anomalies

    Science.gov (United States)

    Gentemann, C. L.; Fewings, M. R.; Garcia-Reyes, M.

    2016-12-01

    In 2014-2016, sea-surface temperatures (SSTs) in the region along the Washington, Oregon, and California coasts were significantly warmer than usual, with a maximum SST anomaly of 6.2°C measured near Santa Barbara. This marine heat wave was associated with major ecosystem disturbances, including a toxic algae bloom of Pseudo-nitzschia that had massive economic and ecological impacts. Here, we use satellite and blended reanalysis products to report the magnitude, extent, duration, and evolution of SST, wind stress, and wind stress curl anomalies along the west coast of the continental United States during 2014-2016. Using high-resolution wind stress instead of the Bakun upwelling index shows clear differences in upwelling phenology in 2015.

  7. Protocol for the value of urodynamics prior to stress incontinence surgery (VUSIS study: a multicenter randomized controlled trial to assess the cost effectiveness of urodynamics in women with symptoms of stress urinary incontinence in whom surgical treatment is considered

    Directory of Open Access Journals (Sweden)

    Kleinjan Jan H

    2009-07-01

    Full Text Available Abstract Background Stress urinary incontinence (SUI is a common problem. In the Netherlands, yearly 64.000 new patients, of whom 96% are women, consult their general practitioner because of urinary incontinence. Approximately 7500 urodynamic evaluations and approximately 5000 operations for SUI are performed every year. In all major national and international guidelines from both gynaecological and urological scientific societies, it is advised to perform urodynamics prior to invasive treatment for SUI, but neither its effectiveness nor its cost-effectiveness has been assessed in a randomized setting. The Value of Urodynamics prior to Stress Incontinence Surgery (VUSIS study evaluates the positive and negative effects with regard to outcome, as well as the costs of urodynamics, in women with symptoms of SUI in whom surgical treatment is considered. Methods/design A multicentre diagnostic cohort study will be performed with an embedded randomized controlled trial among women presenting with symptoms of (predominant SUI. Urinary incontinence has to be demonstrated on clinical examination and/or voiding diary. Physiotherapy must have failed and surgical treatment needs to be under consideration. Patients will be excluded in case of previous incontinence surgery, in case of pelvic organ prolapse more than 1 centimeter beyond the hymen and/or in case of residual bladder volume of more than 150 milliliter on ultrasound or catheterisation. Patients with discordant findings between the diagnosis based on urodynamic investigation and the diagnosis based on their history, clinical examination and/or micturition diary will be randomized to operative therapy or individually tailored therapy based on all available information. Patients will be followed for two years after treatment by their attending urologist or gynaecologist, in combination with the completion of questionnaires. Six hundred female patients will be recruited for registration from

  8. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    DEFF Research Database (Denmark)

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo;

    2015-01-01

    -dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses...... acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis....

  9. Forecasting of Surface Currents via Correcting Wind Stress with Assimilation of High-Frequency Radar Data in a Three-Dimensional Model

    Directory of Open Access Journals (Sweden)

    Lei Ren

    2016-01-01

    Full Text Available This paper details work in assessing the capability of a hydrodynamic model to forecast surface currents and in applying data assimilation techniques to improve model forecasts. A three-dimensional model Environment Fluid Dynamics Code (EFDC was forced with tidal boundary data and onshore wind data, and so forth. Surface current data from a high-frequency (HF radar system in Galway Bay were used for model intercomparisons and as a source for data assimilation. The impact of bottom roughness was also investigated. Having developed a “good” water circulation model the authors sought to improve its forecasting ability through correcting wind shear stress boundary conditions. The differences in surface velocity components between HF radar measurements and model output were calculated and used to correct surface shear stresses. Moreover, data assimilation cycle lengths were examined to extend the improvements of surface current’s patterns during forecasting period, especially for north-south velocity component. The influence of data assimilation in model forecasting was assessed using a Data Assimilation Skill Score (DASS. Positive magnitude of DASS indicated that both velocity components were considerably improved during forecasting period. Additionally, the improvements of RMSE for vector direction over domain were significant compared with the “free run.”

  10. The Value of Value

    DEFF Research Database (Denmark)

    Sørensen, Asger

    parts of business ethics given prominence to especially one term, namely `value'. The question that interests me is the following: What does the articulation of ethics and morality in terms of values mean for ethics and morality as such. Or, to put the question in a more fashionably way: What...... is the value of value for morality and ethics?To make things a bit more precise, we can make use of the common distinction between ethics and morality, i.e. that morality is the immediate, collective and unconscious employment of morals, whereas ethics is the systematic, individual and conscious reflections...

  11. Intercomparison of four remote-sensing-based energy balance methods to retrieve surface evapotranspiration and water stress of irrigated fields in semi-arid climate

    Science.gov (United States)

    Chirouze, J.; Boulet, G.; Jarlan, L.; Fieuzal, R.; Rodriguez, J. C.; Ezzahar, J.; Er-Raki, S.; Bigeard, G.; Merlin, O.; Garatuza-Payan, J.; Watts, C.; Chehbouni, G.

    2014-03-01

    Instantaneous evapotranspiration rates and surface water stress levels can be deduced from remotely sensed surface temperature data through the surface energy budget. Two families of methods can be defined: the contextual methods, where stress levels are scaled on a given image between hot/dry and cool/wet pixels for a particular vegetation cover, and single-pixel methods, which evaluate latent heat as the residual of the surface energy balance for one pixel independently from the others. Four models, two contextual (S-SEBI and a modified triangle method, named VIT) and two single-pixel (TSEB, SEBS) are applied over one growing season (December-May) for a 4 km × 4 km irrigated agricultural area in the semi-arid northern Mexico. Their performance, both at local and spatial standpoints, are compared relatively to energy balance data acquired at seven locations within the area, as well as an uncalibrated soil-vegetation-atmosphere transfer (SVAT) model forced with local in situ data including observed irrigation and rainfall amounts. Stress levels are not always well retrieved by most models, but S-SEBI as well as TSEB, although slightly biased, show good performance. The drop in model performance is observed for all models when vegetation is senescent, mostly due to a poor partitioning both between turbulent fluxes and between the soil/plant components of the latent heat flux and the available energy. As expected, contextual methods perform well when contrasted soil moisture and vegetation conditions are encountered in the same image (therefore, especially in spring and early summer) while they tend to exaggerate the spread in water status in more homogeneous conditions (especially in winter). Surface energy balance models run with available remotely sensed products prove to be nearly as accurate as the uncalibrated SVAT model forced with in situ data.

  12. Surface wetting strategy prevents acute heat exposure-induced alterations of hypothalamic stress- and metabolic-related genes in broiler chickens.

    Science.gov (United States)

    Rajaei-Sharifabadi, H; Greene, E; Piekarski, A; Falcon, D; Ellestad, L; Donoghue, A; Bottje, W; Porter, T; Liang, Y; Dridi, S

    2017-03-01

    Heat stress (HS) is devastating to poultry production worldwide, yet its biology and molecular responses are not well defined. Although advances in management strategy have partially alleviated the negative impact of HS, productivity still continues to decline when the ambient temperature rises. Therefore, identifying mechanism-based approaches to decrease HS susceptibility while improving production traits is critical. Recently, we made a breakthrough by applying a surface wetting strategy and showing that it improves growth performance compared with the current conventional cooling system. In the present study, we aimed to further define molecular mechanisms associated with surface wetting in ameliorating HS productivity loss in broilers. Five-week-old broiler chickens were exposed to acute HS (35°C for 2 h) alone or in combination with surface wetting. A control group was maintained at thermoneutral conditions (25°C). Core body temperature (BT) and feed intake were recorded. Blood was collected and hypothalamic tissues (main site involved in the regulation of energy homeostasis) were harvested to determine the expression profile of stress- and metabolic-related genes. Surface wetting prevents HS from increasing BT and plasma corticosterone levels ( heat shock protein and adenosine monophosphate-activated protein-induced by HS and significantly modulates the expression of feeding-related hypothalamic neuropeptides (agouti-related protein, proopiomelanocortin, orexin, orexin receptor, and leptin receptor). Taken together, our data represent the first evidence that surface wetting alleviates systemic and intracellular stress induced by HS and preserves the intracellular energy status, which, in turn, may result in improved broiler well-being and growth performance.

  13. Comparison of distribution coefficients (K{sub d} values), sorption isotherms and surface complexation models for evaluating radionuclide sorption in geological media

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Timothy E. [Australian Nuclear Science and Technology Organisation (ANSTO), Menai (Australia); Waite, T. David [School of Civil and Environmental Engineering, University of New South Wales, Sydney (Australia)

    1999-07-01

    The safety assessment of repositories requires models of sorption to be included in the computer codes used for predicting radionuclide migration. Typically, these codes rely on the distribution coefficient (K{sub d} value) to describe sorption. In this paper, the sorption behaviour of U is used as a case study for the development of different types of sorption models. Adsorption isotherms relate the amount of absorbed radionuclide to its dissolved concentration, but usually can not account for the effects of variables such as the pH, ionic strength or the presence of complexing ligands without adjustment of parameter values. The surface complexation model (SCM) offers a more fundamental description of sorption, but requires a large experimental data base, with systematic variation of parameters such as pH and radionuclide concentration. Model uncertainties that derive from the experimental data must be taken into account. The SCM can be used to constrain the range of radionuclide K{sub d} values that may occur in a given environment. (author)

  14. Adding value(s)

    DEFF Research Database (Denmark)

    Carré, David

    2015-01-01

    , 1992). In response, behavioral economics (Camerer, 1999) has shown that agents have values other than optimization underpinning their decisions. Therefore, concerns arose regarding which values are guiding the agent but not about how such values became relevant for the agent. In this presentation, I......Most economic inquires revolve around agents making decisions. Getting the ‘best value’, it is assumed, drives such decisions: gaining most while risking least. This assumption has been debunked by showing that people does not always choose neither maximum benefit nor less risk (Kahneman & Tversky...... will explore the consequences of shifting to the latter perspective, i.e. looking for the generative framework of values. Here I argue that economic behavior should also be seen as a sense-making process, guided by values that are chosen/rejected along with fellow human beings, in specific socio...

  15. Polished Stone Value Test and its relationship with petrographic parameters (hardness contrast and modal composition and surface micro-roughness in natural and artificial aggregates

    Directory of Open Access Journals (Sweden)

    Fernández, A.

    2013-09-01

    Full Text Available The goal of this work was first to establish the relationships between the PSV values and the microstructural and mineralogical features of the aggregates and surface micro-roughness, and then to establish the behavioural differences between natural and artificial aggregates. The results obtained indicate that the surface micro-roughness and the different PSV values of the natural aggregates are strongly governed by the existence of minerals with different degrees of hardness, together with the proportion of these minerals. In contrast, the different degree of porosity in artificial aggregates (a furnace slag was seen to be responsible for its high surface micro-roughness and PSV values. Finally, the PSV and a petrographic parameter (Overall Hardness Contrast, ΔH were seen to be related by an exponential curve (PSV=39.726ΔH0.057 with an extremely good fit, providing a good tool to estimate PSVs in natural and artificial aggregates from petrographic parameters.El objetivo de este trabajo es establecer, por un lado, las relaciones existentes del CPA con las características petrográficas de los áridos, así como su microrrugosidad superficial y, por otro, las diferencias de comportamiento entre áridos naturales y artificiales. Los resultados indican que en los áridos naturales la microrrugosidad superficial y el diferente valor del CPA están determinados, en gran medida, por las diferencias de dureza de sus minerales y también por la proporción en la que estos minerales se encuentran en las distintas litologías. Sin embargo, en los áridos artificiales (escorias de fundición su elevada porosidad es la responsable de su marcada microrrugosidad superficial y su elevado valor del CPA. Finalmente, se relaciona el CPA con un parámetro petrográfico (Contraste de Dureza Global, ΔH mediante una curva exponencial, cuyo excelente índice de regresión hace que sea factible estimar mediante el estudio petrográfico de un árido su valor del CPA

  16. Adsorption and diffusion of atomic oxygen and sulfur at pristine and doped Ni surfaces with implications for stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrov, Vitaly; Sushko, Maria L.; Schreiber, Daniel K.; Bruemmer, Stephen M.; Rosso, Kevin M.

    2016-12-01

    A density-functional-theory modeling study of atomic oxygen/sulfur adsorption and diffusion at pristine and doped Ni(111) and (110) surfaces is presented. We find that oxygen and sulfur feature comparable adsorption energies over the same surface sites, however, the surface diffusion of sulfur is characterized by an activation barrier about one half that of oxygen. Calculations with different alloying elements at Ni surfaces show that Cr strongly enhances surface binding of both species in comparison to Al. These results in combination with previous modeling studies help explain the observed differences in selective grain boundary oxidation mechanisms of Ni-Cr and Ni-Al alloys.

  17. Effects of charge and surface ligand properties of nanoparticles on oxidative stress and gene expression within the gut of Daphnia magna

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Gustavo A.; Lohse, Samuel E.; Torelli, Marco; Murphy, Catherine; Hamers, Robert J.; Orr, Galya; Klaper, Rebecca D.

    2015-05-01

    Concern has been raised regarding the current and future release of engineered nanomaterials into aquatic environments from industry and other sources. However, not all nanomaterials may cause an environ-mental impact and identifying which nanomaterials may be of greatest concern has been difficult. It is thought that the surface groups of a functionalized nanoparticles (NPs) may play a significant role in determining their interactions with aquatic organisms, but the way in which surface properties of NPs impact their toxicity in whole organisms has been minimally explored. A major point of interaction of NPs with aquatic organisms is in the gastrointestinal tract as they ingest particulates from the water column or from the sediment. The main goal of this study was to use model gold NP (AuNPs) to evaluate the potential effects of the different surfaces groups on NPs on the gut of an aquatic model organism, Daphnia magna. In this study, we exposed daphnids to a range of AuNPs concentrations and assessed the impact of AuNP exposure in the daphnid gut by measuring reactive oxygen species (ROS) production and expression of genes associated with oxidative stress and general cellular stress: glutathione S-transferase(gst), catalase (cat), heat shock protein 70 (hsp70), and metallothionein1 (mt1). We found ROS formation and gene expression were impacted by both charge and the specific surface ligand used. We detected some degree of ROS production in all NP exposures, but positively charged AuNPs induced a greater ROS response. Similarly, we observed that, compared to controls, both positively charged AuNPs and only one negatively AuNP impacted expression of genes associated with cellular stress. Finally, ligand-AuNP exposures showed a different toxicity and gene expression profile than the ligand alone, indicating a NP specific effect.

  18. Surface-secreted von Willebrand factor mediates aggregation of ADP-activated platelets at moderate shear stress: facilitated by GPIb but controlled by GPIIb-IIIa.

    Science.gov (United States)

    Frojmovic, M M; Kasirer-Friede, A; Goldsmith, H L; Brown, E A

    1997-03-01

    We previously showed that ADP activation of washed human platelets in plasma-free suspensions supports aggregation at moderate shear stress (0.4-1.6 Nm-2) in Poiseuille flow. Although most activated platelets expressed maximal fibrinogen-occupied GPIIb-IIIa receptors, aggregation appeared to be independent of bound fibrinogen, but blocked by the hexapeptide GRGDSP. Here, we tested the hypothesis that von Willebrand factor (vWF) secreted and expressed on activated platelets mediates aggregation at moderate shear rates from 300 to 1000 s-1 corresponding to shear stresses from 0.3 to 1.1 Nm-2. Relatively unactivated platelets (Flow cytometric measurements with monoclonal antibody (mAb) 2.2.9 reporting on surface-bound vWF, and with mAb S12 reporting on alpha-granule secreted P-selectin, showed that 65% and 80%, respectively, of all platelets were maximally activated with respect to maximal secretion and surface expression of these proteins. "Resting" washed platelets exhibited both surface-bound vWF and significant P-selectin secretion. We showed that mAbs 6D1 and NMC4, respectively blocking the adhesive domains on the GPIb receptor recognizing vWF, and on the vWF molecule recognizing the GPIb receptor, partially inhibited ADP-induced aggregation under shear in Couette flow, the degree of inhibition increasing with increasing shear stress. In contrast, mAb 10E5, blocking the vWF binding domain on GPIIb-IIIa, essentially blocked all aggregation at the shear rates tested. We conclude that vWF, expressed on ADP-activated platelets, is at least the predominant cross-bridging molecule mediating aggregation at moderate shear stress. There is an absolute requirement for free activated GPIIb-IIIa receptors, postulated to interact with platelet-secreted, surface bound vWF. The GPIb-vWF cross-bridging reaction plays a facilitative role becoming increasingly important with increasing shear stress. Since aurin tricarboxylic acid, which blocks the GPIb binding domain on vWF, was

  19. 铣削加工曲面残余应力有限元分析%Finite Element Analysis for Residual Stress of Milling Curved Surface

    Institute of Scientific and Technical Information of China (English)

    曾红; 韩笑; 陈燕燕; 王延忠; 吴林峰

    2013-01-01

      基于Abaqus软件对椭圆球面进行铣削加工仿真分析,通过热-力耦合的有限元理论对曲面表面进行残余应力分析,得到不同的加工参数下,表面残余应力的分布规律及变化规律,并通过正交试验得出影响残余应力的主要加工参数。%Elliptic spherical milling simulation analysis was made based on Abaqus software.Finite element theory of thermal-me-chanical coupling was used to make residual stress analysis for curved surface.Under different processing parameters,distribution and variation of surface residual stress were obtained.Through the orthogonal test,the main processing parameters affecting the residual stress were gotten.

  20. Electrical-stress-induced transport and surface potential characterizations of metal/ TiO 2/metal planar junctions

    Science.gov (United States)

    Kim, Haeri; Kim, Dong-Wook

    2011-03-01

    Electric-field-induced resistive switching (RS) phenomena in metal oxides have attracted considerable research interest due to their potential use in nonvolatile memory device applications. Intensive investigations have revealed that coupled electron ion dynamics play a key role the RS mechanism. Metal/single crystal junction can be an ideal model system to study how the ionic drift and diffusion can affect the resistance. We investigated transport and local electrical properties of Pt/ Ti O2 single crystal/Ti planar junctions with micron- sized gaps between the electrodes. Scanning Kelvin probe microscopy (SKPM) showed that negative (positive) electrical stress to the Pt electrodes significantly reduced (hardly affected) the Pt/ Ti O2 contact resistance. The SKPM results also revealed that the electrical stress caused alteration of the local work function of Ti O2 . The comparative investigations of the transport and SKPM results suggested that the electrical stress induced redistribution of ions, resulting in the change of the junction resistance.

  1. The prognostic value of heart rate response during vasodilator stress myocardial perfusion imaging in patients with end-stage renal disease undergoing renal transplantation.

    Science.gov (United States)

    AlJaroudi, Wael; Anokwute, Chiedozie; Fughhi, Ibtihaj; Campagnoli, Tania; Wassouf, Marwan; Vij, Aviral; Kharouta, Michael; Appis, Andrew; Ali, Amjad; Doukky, Rami

    2017-09-18

    In asymptomatic end-stage renal disease (ESRD) patients undergoing vasodilator stress myocardial perfusion imaging (MPI) prior to renal transplantation (RT), the impact of pre-transplant heart rate response (HRR) to vasodilator stress on post-RT outcomes is unknown. We analyzed a retrospective cohort of asymptomatic patients with ESRD who underwent a vasodilator stress SPECT-MPI and subsequently received RT. Blunted HRR was defined as HRR <28% for regadenoson stress and <20% for adenosine stress. The primary endpoint was major adverse cardiac events (MACE), defined as cardiac death or myocardial infarction. Clinical risk was assessed using the sum of risk factors set forth by the AHA/ACCF consensus statement on the assessment of RT candidates. Among 352 subjects, 140 had an abnormal pre-transplant HRR. During a mean follow-up of 3.2 ± 2.0 years, 85 (24%) MACEs were observed. Blunted HRR was associated with increased MACE risk (hazard ratio 1.72; 95% confidence interval 1.12-2.63, P = 0.013), and remained significant after adjustment for gender, sum of AHA/ACCF risk factors, summed stress score, baseline heart rate, and β-blocker use. HRR was predictive of MACE in patients with normal MPI and irrespective of clinical risk. Blunted HRR was associated with a significant increase in post-operative (30-day) MACE risk (17.9% vs 8.5%; P = 0.009). In asymptomatic ESRD patients being evaluated for RT, a blunted pre-transplant HRR was predictive of post-RT MACE. HRR may be a valuable tool in the risk assessment of RT candidates.

  2. Effect of irregularity on torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half-space

    Science.gov (United States)

    Saha, Anup; Kundu, Santimoy; Gupta, Shishir; Vaishnav, Pramod Kumar

    2016-06-01

    The present paper is concerned with the propagation of torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half-space. We assume the quadratic inhomogeneity in rigidity and density in the lower half-space and irregularity is taken in the form of rectangle at the interface separating the layer from the lower half-space. The dispersion equation for torsional waves has been obtained in a closed form. Velocity equation is also obtained in the absence of irregularity. The study reveals that the presence of irregularity, initial stress, porosity, inhomogeneity and anisotropy factor in the dispersion equation approves the significant effect of these parameters in the propagation of torsional waves in porous medium. It has also been observed that for a uniform media, the velocity equation reduces to the classical result of Love wave.

  3. The Coral Reef Temperature Anomaly Database (CoRTAD) Version 3 - Global, 4 km Sea Surface Temperature and Related Thermal Stress Metrics for 1982-2009 (NODC Accession 0068999)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coral Reef Temperature Anomaly Database (CoRTAD) is a collection of sea surface temperature (SST) and related thermal stress metrics, developed specifically for...

  4. The Coral Reef Temperature Anomaly Database (CoRTAD) Version 4 - Global, 4 km Sea Surface Temperature and Related Thermal Stress Metrics for 1981-10-31 to 2010-12-31 (NODC Accession 0087989)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coral Reef Temperature Anomaly Database (CoRTAD) is a collection of sea surface temperature (SST) and related thermal stress metrics, developed specifically for...

  5. The Coral Reef Temperature Anomaly Database (CoRTAD) Version 5 - Global, 4 km Sea Surface Temperature and Related Thermal Stress Metrics for 1982-2012 (NCEI Accession 0126774)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Version 5 of the Coral Reef Temperature Anomaly Database (CoRTAD) is a global, 4 km, sea surface temperature (SST) and related thermal stress metrics dataset for...

  6. The Coral Reef Temperature Anomaly Database (CoRTAD) Version 2 - Global, 4 km Sea Surface Temperature and Related Thermal Stress Metrics for 1982-2008 (NODC Accession 0054501)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coral Reef Temperature Anomaly Database (CoRTAD) is a collection of sea surface temperature (SST) and related thermal stress metrics, developed specifically for...

  7. QT interval variability in body surface ECG : measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESC Working Group on Cardiac Cellular Electrophysiology

    NARCIS (Netherlands)

    Baumert, Mathias; Porta, Alberto; Vos, Marc A; Malik, Marek; Couderc, Jean-Philippe; Laguna, Pablo; Piccirillo, Gianfranco; Smith, Godfrey L; Tereshchenko, Larisa G; Volders, Paul G A

    2016-01-01

    This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the

  8. Production of an antibiotic enterocin from a marine actinobacteria strain H1003 by metal-stress technique with enhanced enrichment using response surface methodology.

    Science.gov (United States)

    Hassan, Syed Shamsul; Shah, Sayed Asmat Ali; Pan, Chengqian; Fu, Leilei; Cao, Xun; Shi, Yutong; Wu, Xiaodan; Wang, Kuiwu; Wu, Bin

    2017-01-01

    Elicitation by chemical means including heavy metals is one of a new technique for drug discoveries. In this research, the effect of heavy metals on marine actinobacteria Streptomyces sp. H-1003 for the production of enterocin, with a strong broad spectrum activity, along optimized fermented medium was firstly investigated. The optimum metal stress conditions consisted of culturing marine actinobacteria strain H-1003 with addition of cobalt ions at 2mM in optimized Gause's medium having starch at 20mg/L for 10 days at 180 revolution/min. Under these conditions, enterocin production was enhanced with a value of 5.33mg/L, which was totally absent at the normal culture of strain H-1003 and much higher than other tested metal-stress conditions. This work triumphantly announced a prodigious effect of heavy metals on marine actinobacteria with fringe benefits as a key tool of enterocin production.

  9. RPG 行星减速器齿面应力均化分析%The homogenization analysis for tooth surface stress of RPG planetary reductor

    Institute of Scientific and Technical Information of China (English)

    孔霞; 蔡云龙

    2015-01-01

    为避免RPG行星减速器因齿面应力分布不均导致的齿面接触应力增加、齿根弯曲强度下降、行星轮轴承受力不均等问题,以RPG39-50型行星减速器为例,利用有限元方法,构建该型减速器的系统柔性模型,依托行星排框架、行星轮销轴、行星轮轴承及输出排齿轮等关键结构件的变形分析,进行了针对性的齿面优化修形,从而实现了齿面应力均化,有效提高了该齿轮系统的寿命与可靠性。%The RPG planetary redactor is a special redactor with the conditions of large power , low speed and large torque output .The output structure of the RPG planetary redactor is easy to deform of many components , and the unbalanced distribution of tooth surface stress is inevitable .All these problems may cause the worse transmission conditions such as the raise of tooth surface contact stress , the drop of tooth flexural strength and the unbalanced loads of planetary gear bears .Taking RPG39-50 planetary redactor as an example , it uses the finite element method to build the flexible model of the redactor , analyzes the deformation of the components such as the planetary gear frame , the planetary gear shafts , the planetary gear bears and the output gears .At last , it re-alizes the tooth optimization repair .The result homogenizes the tooth surface stress and improves the reliability of the gear transmission system .

  10. Determining the Critical Slip Surface of Three-Dimensional Soil Slopes from the Stress Fields Solved Using the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Yu-chuan Yang

    2016-01-01

    Full Text Available The slope stability problem is an important issue for the safety of human beings and structures. The stability analysis of the three-dimensional (3D slope is essential to prevent landslides, but the most important and difficult problem is how to determine the 3D critical slip surface with the minimum factor of safety in earth slopes. Basing on the slope stress field with the finite element method, a stability analysis method is proposed to determine the critical slip surface and the corresponding safety factor of 3D soil slopes. Spherical and ellipsoidal slip surfaces are considered through the analysis. The moment equilibrium is used to compute the safety factor combined with the Mohr-Coulomb criteria and the limit equilibrium principle. Some assumptions are introduced to reduce the search range of center points and the radius of spheres or ellipsoids. The proposed method is validated by a classical 3D benchmark soil slope. Simulated results indicate that the safety factor of the benchmark slope is 2.14 using the spherical slip surface and 2.19 using the ellipsoidal slip surface, which is close to the results of previous methods. The simulated results indicate that the proposed method can be used for the stability analysis of a 3D soil slope.

  11. Simulation Research on the Surface Residual Stress of Ultrasonic Vibration Honing%超声振动珩磨表面残余应力数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    郑华林; 张伟

    2015-01-01

    目的:磨削产生的残余应力对工件表面特性有重要影响,超声振动珩磨使磨粒具有极大的加速度而改变了材料去除机理,研究超声振动对工件表面残余应力的影响及产生机理。方法分析残余应力形成有限元理论,建立基于热弹塑性有限元法的超声振动单颗CBN磨粒切削40 CrNiMoA热力耦合有限元模型,并设置两次切削、卸载、约束转换及冷却等分析步。通过数值模拟得到不同振动参数下表面残余应力的分布情况,并对模拟结果进行分析。结果有限元计算得到的各分析阶段应力分布存在差别,超声振动参数设置达到仿真要求;对磨粒施加超声振动后珩磨力下降约26%,珩磨热降低约17%,切向残余压应力有所减小,垂直珩磨速度方向拉应力减小并向压应力转变。结论超声振动使珩磨力和珩磨热有一定程度降低从而改变了残余应力的分布及数值;振动频率在20 kHz波动时对残余应力的影响不大;磨削速度减小,切向残余压应力增大,垂直磨削方向残余拉应力减小;振幅增大时,切向残余压应力减小,垂直方向残余应力增大。%ABSTRACT:Objective To study the influence on residual stress as the grinding residual stress has important influence on work-piece surface characteristics and ultrasonic vibration honing makes the grains obtain a great acceleration which changes the material removal mechanism. Methods The residual stress finite element theory was analyzed, the coupled thermal-mechanical finite ele-ment model was established for the ultrasonic vibration honing of a single CBN grain cutting 40CrNiMoA based on the thermal elas-tic-plastic theory. Steps of two cutting processes, unloading, constraint transformation and the cooling analysis were set. The sur-face residual stress distribution was obtained by numerical simulation under different vibration parameters and the simulation results

  12. Geopotential Stress

    DEFF Research Database (Denmark)

    Schiffer, Christian; Nielsen, S.B.

    Density heterogeneity in the Earth’s lithosphere causes lateral pressure variations. Horizontal gradients of the vertically integrated lithostatic pressure, the Geopotential Energy (GPE), are a source of stresses (Geopotential Stress) that contribute to the Earth’s Stress Field. In theory the GPE...... is linearly related to the lithospheric part of the Geoid. The Geopotential Stress can be calculated if either the density structure and as a consequence the GPE or the lithospheric contribution to the Geoid is known. The lithospheric Geoid is usually obtained by short pass filtering of satellite Geoid...... are not entirely suitable for the stress calculations but can be compiled and adjusted. We present an approach in which a global lithospheric density model based on CRUST2.0 is obtained by simultaneously fitting topography and surface heat flow in the presence of isostatic compensation and long-wavelength lateral...

  13. Near-surface seismic velocity changes in a salt-dominated environment due to shaking and thermal stressing

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-05-01

    We report on results from a seismic station of the Integrated Plate Boundary Observatory Chile (IPOC) showing a superior sensitivity of seismic velocity changes in the surrounding medium to shaking and temperature. 5 years of daily autocorrelations of the IPOC network are analyzed with passive image interferometry. Due to the particular geological conditions we observe a high sensitivity of the medium around the station near Patache (PATCX) resulting in annual periodic velocity variations and temporary velocity reductions induced by ground shaking. We observe a linear relationship between the amplitude of the velocity reductions and the peak ground acceleration (PGA) of nearby earthquakes at station PATCX. Although velocity reductions are also observed at other stations of the IPOC array for the Mw 7.7 Tocopilla earthquake a clear relationship between the PGA of this earthquake and the induced velocity reductions at the different stations is not visible. Furthermore, we observe velocity variations with an annual and daily period. We present different arguments that these periodic changes are caused by variations of the atmospheric temperature. In this context we construct a model that starts at observed temperature variations and evaluates thermal stresses induced by the temperature gradients. Using radiative transfer based sensitivity kernels and third order elastic constants we relate the distribution of thermal stress in the subsurface to observable time shifts of coda waves. The model is able to reproduce the major features confirming that stress changes in the subsurface can be detected with noise based monitoring.

  14. Postseismic viscoelastic deformation and stress. Part 2: Stress theory and computation; dependence of displacement, strain, and stress on fault parameters

    Science.gov (United States)

    Cohen, S. C.

    1979-01-01

    A viscoelastic model for deformation and stress associated with earthquakes is reported. The model consists of a rectangular dislocation (strike slip fault) in a viscoelastic layer (lithosphere) lying over a viscoelastic half space (asthenosphere). The time dependent surface stresses are analyzed. The model predicts that near the fault a significant fraction of the stress that was reduced during the earthquake is recovered by viscoelastic softening of the lithosphere. By contrast, the strain shows very little change near the fault. The model also predicts that the stress changes associated with asthenospheric flow extend over a broader region than those associated with lithospheric relaxation even though the peak value is less. The dependence of the displacements, stresses on fault parameters studied. Peak values of strain and stress drop increase with increasing fault height and decrease with fault depth. Under many circumstances postseismic strains and stresses show an increase with decreasing depth to the lithosphere-asthenosphere boundary. Values of the strain and stress at distant points from the fault increase with fault area but are relatively insensitive to fault depth.

  15. Research on the influence of machining introduced sub-surface defects and residue stress upon the mechanical properties of single crystal copper

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Large scale molecular dynamics simulations of nanomachining and stretching of single crystal copper are performed to analyze the machining process’ influence on the material’s mechanical properties. The simulation results show that the machining process will introduce interfacial defects inside the specimen and enhance the compressive stress beneath the surface. Gener- ally speaking, interfacial defects lead to the decrease of the strength limit, while residue compressive stress can enhance the elastic limit and even the strength limit. Various machining parameters are adopted to investigate their influence on the me- chanical behavior of machined specimen. Lower cutting speed and smaller cutting depth lead to less defects and greater residue compressive stress, which brings about better mechanical properties. The elastic limit increases by 36.8% under the cutting depth of 0.73 nm and decreases by 21.1% under the cutting depth of 1.46 nm. The strength limit increases by 7.7% under the cutting speed of 100 m/s and decreases by 28.2% under the cutting speed of 300 m/s.

  16. Surface and Interface Stress Analysis of Thin Film by X-Ray Diffraction%薄膜表面和界面应力的X射线衍射分析(中)

    Institute of Scientific and Technical Information of China (English)

    王宁; 王超群

    2011-01-01

    method can be applied. These methods have very important theoretical and practical value for the stress analysis of thin film, multilayer, hard coating, or near surface area of bulk material. They can also be used for the stress analysis of new electronic thin fdm materials, and supply theoretical basis for the control and improvement of performance.

  17. Surface and Interface Stress Analysis of Thin Film by X-Ray Diffraction%薄膜表面和界面应力的X射线衍射分析(上)

    Institute of Scientific and Technical Information of China (English)

    王宁; 王超群

    2011-01-01

    can be applied. These methods have very important theoretical and practical value for the stress analysis of thin film, multilayer, hard coating, or near surface area of bulk material. They can also be used for the stress analysis of new electronic thin film materials, and supply theoretical basis for the control and improvement of performance.

  18. 薄膜表面和界面应力的X射线衍射分析(下)%Surface and Interface Stress Analysis of Thin Film by X-ray Diffraction

    Institute of Scientific and Technical Information of China (English)

    王宁; 王超群

    2011-01-01

    The measurement of the thin film surface and interface stress is a hot subject in recent years. In principle, there is no significant difference between the stress measurement of thin film and bulk material, which can both be determined by X-ray diffraction. By reference to the literatures involving the stress measurement of thin film and surface region, various analysis methods and measurement strategies in dependence on specimen and measurement conditions, are summarized and evaluated in this research. Some practical measurement methods are commended. For macroscopically e-lastically isotropic and untextured specimens, the thin film stress can be analysized by grazing incident multiple X-ray diffraction method. At this condition, when the incident angle is small, conventional siivty method can be applied. For (hhh) and (MX)) strain measurement, due to the advantage of quasi-isotropy, the sirn)< method can be directly used. For the textured specimen, the material is macroscopically elastically anisotropic. Crystallite group method can be applied. These methods have very important theoretical and practical value for the stress analysis of thin film, multilayer, hard coating, or near surface area of bulk material. They can also be used for the stress analysis of new electronic thin film materials, and supply theoretical basis for the control and improvement of performance.%薄膜表面和界面应力的测量是近年来的热点课题,原则上,薄膜与体材的应力分析方法并无差别,可以通过X射线衍射进行测量.本文以有关薄膜和表面区X射线应力分析的专题评述为蓝本,解读有关依赖于试样和测量条件的分析方法和测量策略.为此,将推荐若干实用的测试方法:对于无织构和宏观弹性各向同性薄膜试样,可采用掠入射多衍射线的薄膜应力分析方法,在这种情况下,当用小入射角时,常规的sin2ψ法可以使用;对于(hhh)和(h00)的应变测量,具有准各向同性

  19. Value of MRI in the diagnosis of stress urinary incontinence in the absence of organ descent; Beitrag der MRT in der Diagnostik der Stress-Harninkontinenz ohne begleitenden Descensus urogenitalis

    Energy Technology Data Exchange (ETDEWEB)

    Beyersdorff, D.; Taupitz, M.; Fischer, T.; Hamm, B. [Humboldt-Univ., Berlin (Germany). Inst. fuer Radiologie; Tunn, R.; Rieprich, M. [Humboldt-Univ., Berlin (Germany). Klinik fuer Gynaekologie und Geburtshilfe

    2001-07-01

    To detect pathomorphological changes of the pelvic floor, the vagina, and the urethra by MR imaging in patients with stress urinary incontinence in the absence of organ descent compared with findings in 10 healthy controls. Materials and Methods: The study included 10 healthy controls and 38 patients with stage II urinary incontinence showing no urge symptoms but a pathological stress profile on urodynamic testing. The subjects underwent MR imaging with a phased-array coil at 1.5 T in addition to urodynamic testing and gynecological examination. The following sequences were used: axial and coronal PD-weighted TSE sequences with a FOV of 20 cm and a section thickness of 4 mm; axial STIR sequence. Sagittal T{sub 2}-weighted HASTE sequences were acquired during pelvic floor contraction, relaxation, and straining maneuvers. Results: In 22/38 cases pathomorphological changes were found by MR imaging. The pathomorphological changes were classified as lateral defects (n = 14) if the musculofascial connection between the levator muscle and the lateral vaginal wall or the butterfly shape of the vagina was absent and as central (n = 16) if changes were detected in the urethral wall. Defects of the pelvic floor muscles were detected in 8 cases. No underlying changes were identified in 16/38 cases. Conclusion: In cases of female urinary incontinence, MR imaging of the pelvic floor can detect pathomorphological changes, which are difficult to identify by clinical examination. MR imaging currently does not allow the detection of morphological changes in all forms of female urinary stress incontinence. (orig.) [German] In einer prospektiven Studie sollen mittels MRT pathomorphologische Veraenderungen des Beckenbodens, der Vagina und der Urethra bei Patientinnen mit Stress-Harninkontinenz (HI) ohne begleitenden Descensus urogenitalis im Vergleich zu Patientinnen ohne HI untersucht werden. Material und Methoden: 38 Patientinnen mit Stress-HI im Stadium II wurden zusaetzlich zur

  20. ESTIMATION OF EFFECTIVE SHEAR STRESS WORKING ON FLAT SHEET MEMBRANE USING FLUIDIZED MEDIA IN MBRs

    Science.gov (United States)

    Zaw, Hlwan Moe; Li, Tairi; Nagaoka, Hiroshi; Mishima, Iori

    This study was aimed at estimating effective shear stress working on flat sheet membrane by the addition of fluidized media in MBRs. In both of laboratory-scale aeration tanks with and without fluidized media, shear stress variations on membrane surface and water phase velocity variations were measured and MBR operation was conducted. For the evaluation of the effective shear stress working on membrane surface to mitigate membrane surface, simulation of trans-membrane pressure increase was conducted. It was shown that the time-averaged absolute value of shear stress was smaller in the reactor with fluidized media than without fluidized media. However, due to strong turbulence in the reactor with fluidized media caused by interaction between water-phase and media and also due to the direct interaction between membrane surface and fluidized media, standard deviation of shear stress on membrane surface was larger in the reactor with fluidized media than without media. Histograms of shear stress variation data were fitted well to normal distribution curves and mean plus three times of standard deviation was defined to be a maximum shear stress value. By applying the defined maximum shear stress to a membrane fouling model, trans-membrane pressure curve in the MBR experiment was simulated well by the fouling model indicting that the maximum shear stress, not time-averaged shear stress, can be regarded as an effective shear stress to prevent membrane fouling in submerged flat-sheet MBRs.

  1. Factors that influence surface PM2.5 values inferred from satellite observations: perspective gained for the Baltimore-Washington Area during DISCOVER-AQ

    Science.gov (United States)

    Crumeyrolle, S.; Chen, G.; Ziemba, L.; Beyersdorf, A.; Thornhill, L.; Winstead, E.; Moore, R.; Shook, M. A.; Anderson, B.

    2013-09-01

    During the NASA DISCOVER-AQ campaign over the Washington D.C., - Baltimore, MD, metropolitan region in July 2011, the NASA P-3B aircraft performed extensive profiling of aerosol optical, chemical, and microphysical properties. These in-situ profiles were coincident with ground based remote sensing (AERONET) and in-situ (PM2.5) measurements. Here, we use this data set to study the correlation between the PM2.5 observations at the surface and the column integrated measurements. Aerosol optical depth (AOD) calculated with the extinction (532 nm) measured during the in-situ profiles was found to be strongly correlated with the volume of aerosols present in the boundary layer (BL). Despite the strong correlation, some variability remains, and we find that the presence of aerosol layers above the BL (in the buffer layer - BuL) introduces a significant uncertainties in PM2.5 estimates based on column-integrated measurements. This motivates the use of active remote sensing techniques to dramatically improve air quality retrievals. Since more than a quarter of the AOD values observed during DISCOVER-AQ are dominated by aerosol water uptake, the f(RH)amb (obtained from two nephelometers at different relative humidities - RHs) is used to study the impact of the aerosol hygroscopicity. The results indicate that PM2.5 can be predicted within a factor of 1.6 even when the vertical variability of the f(RH)amb is assumed to be negligible.

  2. Alkyl hydroperoxide reductase has a role in oxidative stress resistance and in modulating changes in cell-surface properties in Azospirillum brasilense Sp245.

    Science.gov (United States)

    Wasim, Mariam; Bible, Amber N; Xie, Zhihong; Alexandre, Gladys

    2009-04-01

    An ahpC mutant derivative of Azospirillum brasilense Sp245 (strain SK586) that encodes an alkyl hydroperoxide reductase was found to be more sensitive to oxidative stress caused by organic hydroperoxides compared with the wild-type. In addition, the ahpC mutant strain had multiple defects in a large array of cellular functions that were consistent with alteration of cell-surface properties, such as cell morphology in stationary phase, Calcofluor White-, Congo Red- and lectin-binding abilities, as well as cell-to-cell aggregation and flocculation. All phenotypes of the ahpC mutant were complemented by in trans expression of AhpC, and overexpression of AhpC in the wild-type strain was found to affect the same set of phenotypes, suggesting that the pleiotropic effects were caused by the ahpC mutation. SK586 was also found to be fully motile, but it lost motility at a higher rate than the wild-type during growth, such that most SK586 cells were non-motile in stationary phase. Despite these defects, the mutant did not differ from the wild-type in short-term colonization of sterile wheat roots when inoculated alone, and in competition with the wild-type strain; this implied that AhpC activity may not endow the cells with a competitive advantage in colonization under these conditions. Although the exact function of AhpC in affecting these phenotypes remains to be determined, changes in cell morphology, surface properties, cell-to-cell aggregation and flocculation are common adaptive responses to various stresses in bacteria, and the data obtained here suggest that AhpC contributes to modulating such stress responses in A. brasilense.

  3. Bacterial surface appendages strongly impact nanomechanical and electrokinetic properties of Escherichia coli cells subjected to osmotic stress.

    Directory of Open Access Journals (Sweden)

    Grégory Francius

    Full Text Available The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM and electrokinetics (electrophoresis. Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus. From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO(3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (∼700-900 kPa and ∼100-300 kPa respectively. Under similar ionic strength condition, a dramatic ∼50% to ∼70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the

  4. An investigation of Au/Ti multilayer thin-films: surface morphology, structure and interfacial/surface migration of constituents under applied thermal stress

    Science.gov (United States)

    Senevirathne, Indrajith; Kemble, Eric; Lavoie, John

    2014-03-01

    Multilayer thin films are ubiquitous in industry. Au/Ti/substrate is unique due to possible biological applications in proof of concept devices. Material used for substrates include borosilicate glass, and quartz. Typical Ti depositions on substrates give rise to Stanski-Krastonov (SK) like growth while Frank-van der Merwe (FM) like growth is preferred. Ti films with thickness of ~ 100nm were deposited onto varying substrates using a thermal evaporator. The additional Au layer is then deposited via magnetron sputter deposition at 100mtorr at low deposition rates (~ 1ML/min) onto the Ti thin film. These systems were annealed at varying temperatures and at different durations. Systems were investigated via AFM (Atomic Force Microscopy) probes to examine the surface morphology, and structure. Further, the ambient contamination and elemental distribution/diffusion at annealing was investigated via Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). PASSHE FPDC Annual Grant (LOU # 2010-LHU-03)

  5. Near-Surface Sensing of Vegetative Heavy Metal Stress: Method Development for an Accelerated Assessment of Mine Tailing Waste and Remediation Efforts

    Science.gov (United States)

    Lee, M. T.; Gottfried, M.; Berglund, E.; Rodriguez, G.; Ceckanowicz, D. J.; Cutter, N.; Badgeley, J.

    2014-12-01

    The boom and bust history of mineral extraction in the American southwest is visible today in tens of thousands of abandoned and slowly decaying mine installations that scar the landscape. Mine tailing piles, mounds of crushed mineral ore, often contain significant quantities of heavy metal elements which may leach into surrounding soils, surface water and ground water. Chemical analysis of contaminated soils is a tedious and time-consuming process. Regional assessment of heavy metal contamination for treatment prioritization would be greatly accelerated by the development of near-surface imaging indices of heavy-metal vegetative stress in western grasslands. Further, the method would assist in measuring the ongoing effectiveness of phytoremedatian and phytostabilization efforts. To test feasibility we ground truthed nine phytoremediated and two control sites sites along the mine-impacted Kerber Creek watershed in Saguache County, Colorado. Total metal concentration was determined by XRF for both plant and soil samples. Leachable metals were extracted from soil samples following US EPA method 1312. Plants were identified, sorted into roots, shoots and leaves, and digested via microwave acid extraction. Metal concentrations were determined with high accuracy by ICP-OES analysis. Plants were found to contain significantly higher concentrations of heavy metals than surrounding soils, particularly for manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), barium (Ba), and lead (Pb). Plant species accumulated and distributed metals differently, yet most showed translocation of metals from roots to above ground structures. Ground analysis was followed by near surface imaging using an unmanned aerial vehicle equipped with visible/near and shortwave infrared (0.7 to 1.5 μm) cameras. Images were assessed for spectral shifts indicative of plant stress and attempts made to correlate results with measured soil and plant metal concentrations.

  6. Effect of surface stress and irregularity of the interface on the propagation of SH-waves in the magneto-elastic crustal layer based on a solid semi space

    Indian Academy of Sciences (India)

    D P Acharya; Indrajit Roy

    2009-04-01

    The object of the present paper is to investigate plane SH waves through a magneto-elastic crustal layer based over an elastic, solid semi space under the influence of surface stress on the free surface of the crustal layer and irregularity of the interface. Two types of irregularities of the interface namely, rectangular and parabolic have been considered. Modulations of wave velocity due to the presence of surface stress, irregularity and the magnetic field have been studied separately. Their combined effect has also been investigated. Graphs are drawn to highlight some important peculiarities. It is observed that surface stress, irregularity and magnetic field have their respective role to play in the propagation of SH waves in the crustal layer. Further modulation of wave velocity occurs due to their combined effect.

  7. Regional assimilation of CO2 and δ13C surface data to assess terrestrial biosphere models under drought stress

    Science.gov (United States)

    van der Velde, I. R.; Miller, J. B.; Alden, C. B.; Andrews, A. E.; Schaefer, K. M.; Peters, W.; Tans, P. P.; Vaughn, B. H.; White, J. W. C.

    2016-12-01

    Observed atmospheric carbon dioxide (CO2) and the ratios of its stable isotopologue 13CO2/12CO2 (δ13C) contain unique signals of large-scale drought stress that affect the biosphere. When plants experience physiological stress due to heat and drought at leaf level they respond by closing their stomata. This is a safety mechanism that prevents excessive water loss at the expense of carbon uptake, and it changes the overall water-use efficiency. During photosynthesis, 12CO2 is preferentially assimilated over 13CO2, leaving the atmosphere enriched in 13CO2. Water stress slightly changes the ratio of 13CO2 and 12CO2 molecules being removed from the atmosphere, i.e., a reduction of canopy isotope discrimination (Δ), and its changes are evident in atmospheric δ13C.To improve our understanding of the coupled vegetation-atmosphere system we are developing an ensemble Kalman filter assimilation of high precision measurements of CO2 and δ13C from air samples collected over North America. It uses footprints provided by WRF-STILT that allows for efficient atmospheric transport simulations on a much higher horizontal resolution than with a global Eulerian transport model. To force consistency with atmospheric CO2 and δ13C observations we will optimize regional net terrestrial CO2 exchange (NEE) and Δ from a terrestrial biosphere model. We will carefully evaluate the sensitivity of the optimized parameters to uncertainties in the terrestrial biosphere fluxes, observations, time/space aggregation methods, and boundary conditions. Our main questions are: (i) what signal-to-noise in the data, as interpreted by the model, is large enough to robustly estimate Δ and NEE? and (ii) how do the optimized NEE and Δ that are based on the atmospheric constraint compare with the predicted NEE and Δ that are based on biophysical parameterizations? Our ability to accurately predict the responses of the terrestrial biosphere to changing humidity and soil moisture regimes is currently

  8. THERMAL STRESS IN METEOROIDS BY AERODYNAMIC HEATING

    Institute of Scientific and Technical Information of China (English)

    Chi-YuKing

    2003-01-01

    Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heattransfer coefficient. Given enough time,the tensile stress in the interior of the meteoroid can be as high as 10 kb. This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter. Significant thermal stress(1 kb) can develop quickly (within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large(radius<l m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid's interior. Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes, the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters. In large meteoroids that require longer heating for thermal stress to fully develop, its effect is probably insignificant. The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.

  9. THERMAL STRESS IN METEOROIDS BY AERODYNAMIC HEATING

    Institute of Scientific and Technical Information of China (English)

    Chi-Yu King

    2003-01-01

    Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heattransfer coefficient. Given enough time, the tensile stress in the interior of the meteoroid can be as high as 10 kb. This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter. Significant thermal stress(1 kb) can develop quickly within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large radius<l m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid's interior. Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes, the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters. In large meteoroids that require longer heating for thermal stress to fully develop,its effect is probably insignificant. The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.

  10. I. Measuring and Reducing Stress and Surface Roughness in IBAD MgO Films and II. Developing Tools to Measure Transfer in Undergraduate Chemistry Students

    Science.gov (United States)

    Antonakos, Cory Dale

    I. MgO may be grown with a biaxial texture onto an amorphous substrate with the use of ion beam assisted deposition (IBAD). This MgO film may then be used as a platform on which to grow epitaxial films on an amorphous membrane for characterization purposes. However, the IBAD MgO film is stressed, causing buckles in the amorphous membrane and problems with further film growth on the IBAD MgO. This dissertation work explores the source of this film stress and develops methods to relax the stress and reduce surface roughness with annealing and increased growth temperature. It is determined that annealing and increased growth temperature coupled with a higher ion-to-atom ratio (IAR) during film growth reduce stress and surface roughness sufficiently to use even thinner IBAD MgO films as an intermediate layer between an amorphous membrane and epitaxial film. II. Much of the existing literature on knowledge transfer concludes that transfer is rare and does not occur spontaneously. However, studies supporting that transfer is rare often use methods that focus on binary success or failure to solve a problem correctly and do not analyze thought process. This dissertation work aims at developing transfer questions that allow open-ended responses, developing a method of analysis for these responses that looks for transfer in the problem-solving process, and assessing the methodology itself and its sensitivity, validity, and utility as a general transfer measurement technique for use across a broad range of expertise levels in chemistry. Detailed analysis of responses to each transfer question show that some transfer questions are more effective at distinguishing between expertise levels while also allowing responders of all levels to show knowledge transfer. Simpler questions that are more accessible to students of introductory chemistry proved the most useful at eliciting a range of responses that correlate with expertise level while still showing some degree of transfer in

  11. The roles of vertical mixing, solar radiation, and wind stress in a model simulation of the sea surface temperature seasonal cycle in the tropical Pacfic Ocean

    Science.gov (United States)

    Chen, Dake; Busalacchi, Antonio J.; Rothstein, Lewis M.

    1994-01-01

    The climatological seasonal cycle of sea surface temperature (SST) in the tropical Pacific is simulated using a newly developed upper ocean model. The roles of vertical mixing, solar radiation, and wind stress are investigated in a hierarchy of numerical experiments with various combinations of vertical mixing algorithms and surface-forcing products. It is found that the large SST annual cycle in the eastern equatorial Pacific is, to a large extent, controlled by the annually varying mixed layer depth which, in turn, is mainly determined by the competing effects of solar radiation and wind forcing. With the application of our hybrid vertical mixing scheme the model-simulated SST annual cycle is much improved in both amplitude and phase as compared to the case of a constant mixed layer depth. Beside the strong effects on vertical mixing, solar radiation is the primary heating term in the surface layer heat budget, and wind forcing influences SST by driving oceanic advective processes that redistribute heat in the upper ocean. For example, the SST seasonal cycle in the western Pacific basically follows the semiannual variation of solar heating, and the cycle in the central equatorial region is significantly affected by the zonal advective heat flux associated with the seasonally reversing South Equatorial Current. It has been shown in our experiments that the amount of heat flux modification needed to eliminate the annual mean SST errors in the model is, on average, no larger than the annual mean uncertainties among the various surface flux products used in this study. Whereas a bias correction is needed to account for remaining uncertainties in the annual mean heat flux, this study demonstrates that with proper treatment of mixed layer physics and realistic forcing functions the seasonal variability of SST is capable of being simulated successfully in response to external forcing without relying on a relaxation or damping formulation for the dominant surface heat

  12. 钛合金切削加工表面残余应力有限元仿真%Finite Element Simulation on Residual Stress of Machined Titanium Alloy Surface

    Institute of Scientific and Technical Information of China (English)

    刘文文; 刘长毅

    2012-01-01

    采用Johnson- Cook失效准则,建立了钛合金的二维正交切削热-机械应力耦合有限元仿真模型,分析计算了不同切削条件下已加工表面残余应力的分布规律.结果表明:已加工表面层残余应力为拉应力,沿着深度方向由拉应力逐渐过渡到压应力.表面残余应力随着切削速度的增大而增大,在一定的前角变化范围内,随着刀具前角的增大,表面残余拉应力先增大后减小,而随着刀具后角的增大却减小.各加工参数对残余应力层的厚度影响都很小.%Based on Johnson - Cook failure criterion, it establishes 2D orthogonal TC4 cutting model of the coupled temperature - mechanical stress, analyzes the distribution of surface residual stress under different cutting conditions. The results show that the surface residual stress of workpiece is tensile stress. Along the depth direction, the tensile stress is transformed to the compressive stress. Surface residual stress increases with the in-creasing of the cutting speed, in a certain range of rake angle, the tensile residual stress on the workpiece surface increases with rake angle at first and decreases subsequently, while decreases with the in - creasing of the relief angle. All cutting conditions have little influence on the thickness of the residual stress layer.

  13. Gravitational stresses in anisotropic rock masses

    Science.gov (United States)

    Amadei, B.; Savage, W.Z.; Swolfs, H.S.

    1987-01-01

    This paper presents closed-form solutions for the stress field induced by gravity in anisotropic rock masses. These rocks are assumed to be laterally restrained and are modelled as a homogeneous, orthotropic or transversely isotropic, linearly elastic material. The analysis, constrained by the thermodynamic requirement that strain energy be positive definite, gives the following important result: inclusion of anisotropy broadens the range of permissible values of gravity-induced horizontal stresses. In fact, for some ranges of anisotropic rock properties, it is thermodynamically admissible for gravity-induced horizontal stresses to exceed the vertical stress component; this is not possible for the classical isotropic solution. Specific examples are presented to explore the nature of the gravity-induced stress field in anisotropic rocks and its dependence on the type, degree and orientation of anisotropy with respect to the horizontal ground surface. ?? 1987.

  14. Effect of irregularity on torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half-space

    Indian Academy of Sciences (India)

    Anup Saha; Santimoy Kundu; Shishir Gupta; Pramod Kumar Vaishnav

    2016-06-01

    The present paper is concerned with the propagation of torsional surface waves in an initially stressedanisotropic porous layer sandwiched between homogeneous and non-homogeneous half-space. We assumethe quadratic inhomogeneity in rigidity and density in the lower half-space and irregularity is taken inthe form of rectangle at the interface separating the layer from the lower half-space. The dispersionequation for torsional waves has been obtained in a closed form. Velocity equation is also obtained inthe absence of irregularity. The study reveals that the presence of irregularity, initial stress, porosity,inhomogeneity and anisotropy factor in the dispersion equation approves the significant effect of theseparameters in the propagation of torsional waves in porous medium. It has also been observed that fora uniform media, the velocity equation reduces to the classical result of Love wave.

  15. In-situ synchrotron micro-diffraction study of surface, interface, grain structure, and strain/stress evolution during Sn whisker/hillock formation

    Science.gov (United States)

    Pei, Fei; Jadhav, Nitin; Buchovecky, Eric; Bower, Allan F.; Chason, Eric; Liu, Wenjun; Tischler, Jonathan Z.; Ice, Gene E.; Xu, Ruqing

    2016-03-01

    We have performed X-ray synchrotron micro-diffraction measurements to study the processes controlling the formation of hillocks and whiskers in Sn layers on Cu. The studies were done in real-time on Sn layers that were electro-deposited immediately before the X-ray measurements were started. This enabled a region of the sample to be monitored from the as-deposited state until after a hillock feature formed. In addition to measuring the grain orientation and deviatoric strain (via Laue diffraction), the X-ray fluorescence was monitored to quantify the evolution of the Sn surface morphology and the formation of intermetallic compound (IMC) at the Sn-Cu interface. The results capture the simultaneous growth of the feature and the corresponding film stress, grain orientation, and IMC formation. The observations are compared with proposed mechanisms for whisker/hillock growth and nucleation.

  16. In-situ synchrotron micro-diffraction study of surface, interface, grain structure, and strain/stress evolution during Sn whisker/hillock formation

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Fei; Bower, Allan F.; Chason, Eric [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Jadhav, Nitin [IBM, Hopewell Junction, New York 12533 (United States); Buchovecky, Eric [Saint-Gobain, Northboro R& D Center, Northborough, Massachusetts 01532 (United States); Liu, Wenjun; Tischler, Jonathan Z.; Xu, Ruqing [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Ice, Gene E. [Oak Ridge National Lab, Oak Ridge, Tennessee 37831 (United States)

    2016-03-14

    We have performed X-ray synchrotron micro-diffraction measurements to study the processes controlling the formation of hillocks and whiskers in Sn layers on Cu. The studies were done in real-time on Sn layers that were electro-deposited immediately before the X-ray measurements were started. This enabled a region of the sample to be monitored from the as-deposited state until after a hillock feature formed. In addition to measuring the grain orientation and deviatoric strain (via Laue diffraction), the X-ray fluorescence was monitored to quantify the evolution of the Sn surface morphology and the formation of intermetallic compound (IMC) at the Sn-Cu interface. The results capture the simultaneous growth of the feature and the corresponding film stress, grain orientation, and IMC formation. The observations are compared with proposed mechanisms for whisker/hillock growth and nucleation.

  17. Added value of stress related gene inductions in HepG2 cells as effect measurement in monitoring of air pollution

    Science.gov (United States)

    Nobels, Ingrid; Vanparys, Caroline; Van den Heuvel, Rosette; Vercauteren, Jordy; Blust, Ronny

    2012-08-01

    In this study we studied the effects of particulate matter samples (PM) through gene expression analysis in a routine air quality monitoring campaign by the Flemish Environment Agency (VMM, Belgium). We selected a human hepatoma (HepG2) multiple endpoint reporter assay for targeted stress related endpoint screening. Organic extracts of air samples (total suspended particles, TSP) were collected during one year in an industrial, urban and background location in Flanders, Belgium. Simultaneously, meteorological conditions (temperature, wind speed and precipitation) and particulate matter size ≤ 10 μM (PM10), organic (OC), elemental (EC) and total (TC) carbon were monitored and air samples were collected for chemical analysis (11 PAHs). Correlations between the induction of the different stress genes and the chemical pollutants were analysed. Exposure of HepG2 cells to daily air equivalents (20 m3) of organic TSP extracts revealed the dominant induction of the xenobiotic response element (Xre) and phase I (Cyp1A1) and phase II (GstYa) biotransformation enzymes. Additional effects were the induction of c-Fos, a proto-oncogen and Gadd45, a marker for cell cycle disturbance and responsive to genotoxic compounds. Inductions of other relevant pathways, such as sequestration of heavy metals, retinoids response, protein misfolding and increased cAMP levels were measured occasionally. A significant correlation was found between the genes Cyp1A1 (a typical marker for presence of PAHs and dioxin like compounds), c-Fos, Gadd45, (responsive to DNA damaging compounds) and the amount of PM10 and elemental carbon (EC) whereas no correlation was found between these genes and total PAHs content. This may suggest that the observed induction of Cyp1A1 and DNA damage related genes was provoked (partially) by other particle bound compounds (e.g. pesticides, PCBs, brominated flame retardants, dioxins, …), than PAHs. The contribution of particle bound compounds, other than PAHs might

  18. Role of the plant-specific endoplasmic reticulum stress-inducible gene TIN1 in the formation of pollen surface structure in Arabidopsis thaliana

    KAUST Repository

    Iwata, Yuji

    2012-01-01

    Accumulation of unfolded proteins in the endoplasmic reticulum (ER) of eukaryotic cells triggers the transcriptional activation of ER-resident molecular chaperones and folding enzymes to maintain cellular homeostasis. This process is known as the ER stress response or the unfolded protein response. We have identified tunicamycin induced 1 (TIN1), a plant-specific ER stress-inducible Arabidopsis thaliana gene. The TIN1 protein is localized in the ER; however, its molecular function has yet to be clarified. In this study, we performed functional analysis of TIN1 in planta. RT-PCR analysis showed that TIN1 is highly expressed in pollen. Analysis using the β-glucuronidase reporter gene demonstrated that the TIN1 promoter is active throughout pollen development, peaking at the time of flowering and in an ovule of an open flower. Although a T-DNA insertion mutant of TIN1 grows normally under ambient laboratory conditions, abnormal pollen surface morphology was observed under a scanning electron microscope. Based on the current and previous observations, a possible physiological function of TIN1 during pollen development is discussed. © 2012 The Japanese Society for Plant Cell and Molecular Biology.

  19. An oral absorbent, surface-deacetylated chitin nano-fiber ameliorates renal injury and oxidative stress in 5/6 nephrectomized rats.

    Science.gov (United States)

    Anraku, Makoto; Tabuchi, Ryo; Ifuku, Shinsuke; Nagae, Tomone; Iohara, Daisuke; Tomida, Hisao; Uekama, Kaneto; Maruyama, Toru; Miyamura, Shigeyuki; Hirayama, Fumitoshi; Otagiri, Masaki

    2017-04-01

    In this study, we report that surface-deacetylated chitin nano-fibers (SDACNFs) are more effective in decreasing renal injury and oxidative stress than deacetylated chitin powder (DAC) in 5/6 nephrectomized rats. An oral administration of low doses of SDACNFs (40mg/kg/day) over a 4 week period resulted in a significant decrease in serum indoxyl sulfate, creatinine and urea nitrogen levels, compared with a similar treatment with DAC or AST-120. The SDACNFs treatment also resulted in an increase in antioxidant potential, compared with that for DAC or AST-120. Immunohistochemical analyses also demonstrated that SDACNFs treated CRF rats showed a decrease in the amount of accumulated 8-OHdG compared with the CRF group. These results suggest that the ingestion of SDCH-NF results in a significant reduction in the levels of pro-oxidants, such as uremic toxins, in the gastrointestinal tract, thereby inhibiting the subsequent development of oxidative stress in the systemic circulation.

  20. The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

    Science.gov (United States)

    Kahre, Melinda A.; Hollingsworth, Jeffery

    2012-01-01

    The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

  1. On the value of surface saturated area dynamics mapped with thermal infrared imagery for modeling the hillslope-riparian-stream continuum

    Science.gov (United States)

    Glaser, Barbara; Klaus, Julian; Frei, Sven; Frentress, Jay; Pfister, Laurent; Hopp, Luisa

    2016-10-01

    The highly dynamic processes within a hillslope-riparian-stream (HRS) continuum are known to affect streamflow generation, but are yet not fully understood. Within this study, we simulated a headwater HRS continuum in western Luxembourg with an integrated hydrologic surface subsurface model (HydroGeoSphere). The model was setup with thorough consideration of catchment-specific attributes and we performed a multicriteria model evaluation (4 years) with special focus on the temporally varying spatial patterns of surface saturation. We used a portable thermal infrared (TIR) camera to map surface saturation with a high spatial resolution and collected 20 panoramic snapshots of the riparian zone (approx. 10 m × 20 m) under different hydrologic conditions. Qualitative and quantitative comparison of the processed TIR panoramas and the corresponding model output panoramas revealed a good agreement between spatiotemporal dynamic model and field surface saturation patterns. A double logarithmic linear relationship between surface saturation extent and discharge was similar for modeled and observed data. This provided confidence in the capability of an integrated hydrologic surface subsurface model to represent temporal and spatial water flux dynamics at small (HRS continuum) scales. However, model scenarios with different parameterizations of the riparian zone showed that discharge and surface saturation were controlled by different parameters and hardly influenced each other. Surface saturation only affected very fast runoff responses with a small volumetric contribution to stream discharge, indicating that the dynamic surface saturation in the riparian zone does not necessarily imply a major control on runoff generation.

  2. Heat transfer and thermal stress analysis in grooved tubes

    Indian Academy of Sciences (India)

    Veysel Özceyhan; Necdet Altuntop

    2005-08-01

    Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was applied from the external surface of the tube. Energy and governing flow equations were solved using finite difference scheme. Finite element method (FEM) was used to compute the thermal stress fields. Grooving effects on the thermal stress ratio have been discussed. As a result, maximum thermal stress occurs in the case of $p = d$ for all water inlet velocities. The maximum thermal stress ratio positions inside the tube have been indicated as MX for all investigated cases. In the light of the thermal stress values, various designs can be applied to reduce thermal stress in grooved tubes.

  3. A biomarker panel (Bioscore incorporating monocytic surface and soluble TREM-1 has high discriminative value for ventilator-associated pneumonia: a prospective observational study.

    Directory of Open Access Journals (Sweden)

    Vimal Grover

    Full Text Available Ventilator-associated pneumonia (VAP increases mortality in critical illness. However, clinical diagnostic uncertainty persists. We hypothesised that measuring cell-surface and soluble inflammatory markers, incorporating Triggering Receptor Expressed by Myeloid cells (TREM-1, would improve diagnostic accuracy.A single centre prospective observational study, set in a University Hospital medical-surgical intensive Care unit, recruited 91 patients into 3 groups: 27 patients with VAP, 33 ventilated controls without evidence of pulmonary sepsis (non-VAP, and 31 non-ventilated controls (NVC, without clinical infection, attending for bronchoscopy. Paired samples of Bronchiolo-alveolar lavage fluid (BALF and blood from each subject were analysed for putative biomarkers of infection: Cellular (TREM-1, CD11b and CD62L and soluble (IL-1β, IL-6, IL-8, sTREM-1, Procalcitonin. Expression of cellular markers on monocytes and neutrophils were measured by flow cytometry. Soluble inflammatory markers were determined by ELISA. A biomarker panel ('Bioscore', was constructed, tested and validated, using Fisher's discriminant function analysis, to assess its value in distinguishing VAP from non VAP.The expression of TREM-1 on monocytes (mTREM-1 and neutrophils (nTREM-1 and concentrations of IL-1β, IL-8, and sTREM-1 in BALF were significantly higher in VAP compared with non-VAP and NVC (p<0.001. The BALF/blood mTREM-1 was significantly higher in VAP patients compared to non-VAP and NVC (0.8 v 0.4 v 0.3 p<0.001. A seven marker Bioscore (BALF/blood ratio mTREM-1 and mCD11b, BALF sTREM-1, IL-8 and IL-1β, and serum CRP and IL-6 correctly identified 88.9% of VAP cases and 100% of non-VAP cases.A 7-marker bioscore, incorporating cellular and soluble TREM-1, accurately discriminates VAP from non-pulmonary infection.

  4. L band radar backscatter dependence upon surface wind stress - A summary of new Seasat-1 and aircraft observations

    Science.gov (United States)

    Thompson, T. W.; Weissman, D. E.; Gonzalez, F. I.

    1983-01-01

    The wind-scale relationships for L band radar wavelengths near 25 cm and 20 deg angle of incidence and HH polarization are reviewed using a number of aircraft and Seasat-1 SAR observations. The dependence of the L band backscatter coefficient from the ocean upon surface wind speed and direction is stated. The wind speed coefficient is 0.5 + or - 0.1 for a wide range of wind speeds. The wind direction coefficient is near zero for lower winds and stable marine boundary layers, but may be 0.20 + or - 0.05 for moderate wind speeds and an unstable marine boundary layer. These results are interpreted in terms of existing theoretical models for radar scattering from the ocean.

  5. Bone mineral content in the spongiosa of the lumbar spine of healthy perimenopausal women measured by QCT. Normal values and their relationship to mechanical stress of the vertebral column

    Energy Technology Data Exchange (ETDEWEB)

    Montag, M.; Meyer-Galander, H.M.; Peters, P.E.; Doeren, M.; Montag, T.

    1988-04-01

    Healthy perimenopausal women (152) were examined by QCT to quantify the mineral content of the axial skeleton. The density was measured in the spongiosa of the L 2-4, using single energy technique and the Cann-Genant calibration phantom. The women, aged 37 to 64, had no history of pathological fractures, ovariectomy, metabolic disease, or hormone therapy. The age-related mean values were 25 mg K2HP04cm/sup 3/ lower than the normal values reported by Genant et al. for 203 healthy American women. The 95% confidence interval was distinctly narrower (+-40 mgcm/sup 3/) than the American confidence interval (+-60 mgcm/sup 3/). To evaluate the relationship of the BMC to mechanical stress, the BMC was compared with body weight, body mass index (weightheight/sup 2/), and the lumbar muscle mass was estimated from cross sections of the paravertebral muscles in the CT images. The assumption that higher mechanical stress results in higher bone mineralization could not be confirmed.

  6. Guidance proposal for using available DegT50 values for estimation of degradation rates of plant protection products in Dutch surface water and sediment

    NARCIS (Netherlands)

    Boesten, J.J.T.I.; Adriaanse, P.I.; Horst, ter M.M.S.; Tiktak, A.; Linden, van der A.M.A.

    2014-01-01

    The degradation rate of plant protection products and their transformation products in surface water and sediment may influence their concentrations in Dutch surface water. Therefore the estimation of these rates may be an important part of the assessment of the exposure of aquatic organisms. We

  7. Public Values

    DEFF Research Database (Denmark)

    Beck Jørgensen, Torben; Rutgers, Mark R.

    2015-01-01

    administration is approached in terms of processes guided or restricted by public values and as public value creating: public management and public policy-making are both concerned with establishing, following and realizing public values. To study public values a broad perspective is needed. The article suggest......This article provides the introduction to a symposium on contemporary public values research. It is argued that the contribution to this symposium represent a Public Values Perspective, distinct from other specific lines of research that also use public value as a core concept. Public...... a research agenda for this encompasing kind of public values research. Finally the contributions to the symposium are introduced....

  8. Residual stress distribution in rabbit limb bones.

    Science.gov (United States)

    Yamada, Satoshi; Tadano, Shigeru; Fujisaki, Kazuhiro

    2011-04-29

    The presence of the residual stresses in bone tissue has been noted and the authors have reported that there are residual stresses in bone tissue. The aim of our study is to measure the residual stress distribution in the cortical bone of the extremities of vertebrates and to describe the relationships with the osteon population density. The study used the rabbit limb bones (femur, tibia/fibula, humerus, and radius/ulna) and measured the residual stresses in the bone axial direction at anterior and posterior positions on the cortical surface. The osteons at the sections at the measurement positions were observed by microscopy. As a result, the average stresses at the hindlimb bones and the forelimb bones were 210 and 149 MPa, respectively. In the femur, humerus, and radius/ulna, the residual stresses at the anterior position were larger than those at the posterior position, while in the tibia, the stress at the posterior position was larger than that at the anterior position. Further, in the femur and humerus, the osteon population densities in the anterior positions were larger than those in the posterior positions. In the tibia, the osteon population density in the posterior position was larger than that in the anterior position. Therefore, tensile residual stresses were observed at every measurement position in the rabbit limb bones and the value of residual stress correlated with the osteon population density (r=0.55, P<0.01).

  9. Two-dimensional simulation by regularization of free surface viscoplastic flows with Drucker-Prager yield stress and application to granular collapse

    Science.gov (United States)

    Lusso, Christelle; Ern, Alexandre; Bouchut, François; Mangeney, Anne; Farin, Maxime; Roche, Olivier

    2017-03-01

    This work is devoted to numerical modeling and simulation of granular flows relevant to geophysical flows such as avalanches and debris flows. We consider an incompressible viscoplastic fluid, described by a rheology with pressure-dependent yield stress, in a 2D setting with a free surface. We implement a regularization method to deal with the singularity of the rheological law, using a mixed finite element approximation of the momentum and incompressibility equations, and an arbitrary Lagrangian Eulerian (ALE) formulation for the displacement of the domain. The free surface is evolved by taking care of its deposition onto the bottom and of preventing it from folding over itself. Several tests are performed to assess the efficiency of our method. The first test is dedicated to verify its accuracy and cost on a one-dimensional simple shear plug flow. On this configuration we setup rules for the choice of the numerical parameters. The second test aims to compare the results of our numerical method to those predicted by an augmented Lagrangian formulation in the case of the collapse and spreading of a granular column over a horizontal rigid bed. Finally we show the reliability of our method by comparing numerical predictions to data from experiments of granular collapse of both trapezoidal and rectangular columns over horizontal rigid or erodible granular bed made of the same material. We compare the evolution of the free surface, the velocity profiles, and the static-flowing interface. The results show the ability of our method to deal numerically with the front behavior of granular collapses over an erodible bed.

  10. Effects of free air carbon dioxide enrichment and drought stress on the feed value of maize silage fed to sheep at different thermal regimes.

    Science.gov (United States)

    Lohölter, Malte; Meyer, Ulrich; Manderscheid, Remy; Weigel, Hans-Joachim; Erbs, Martin; Flachowsky, Gerhard; Dänicke, Sven

    2012-08-01

    Information about the effects of rising atmospheric CO2 concentration and drought on the feed value of maize silage and interactions with the thermal environment during feeding is limited. A free air carbon dioxide enrichment facility was operated in a maize field to generate an elevated CO2 concentration of 550 ppm. Drought was induced by the exclusion of precipitation in one half of all experimental plots. Plants were harvested, chopped and ensiled. In a balance experiment on sheep, the nutrient digestibility was determined for three climatic treatments (temperate, temperature humidity index (THI) 57-63; mild heat, THI 68-71; severe heat, THI 75-80). The CO2 concentration and drought did not alter the crude nutrient content of silage dry matter (DM) or nutrient and organic matter (OM) digestibility. Drought increased the concentration of deoxynivalenol (DON, p maize silage due to increased atmospheric CO2 and drought. Enriched CO2 may decrease DON contaminations during drought. The thermal environment during the balance experiment did not interact with feeding maize silage grown under elevated CO2, but may affect cell wall and OM digestibility.

  11. 磁共振STIR和DWI在疲劳骨折诊断中的应用价值%The application value of STIR and DWI of MRI in the stress fracture

    Institute of Scientific and Technical Information of China (English)

    石冬; 刘志; 杜天会; 杨东奎; 郑雷

    2014-01-01

    目的:探讨磁共振STIR和DWI对早期疲劳骨折诊断价值,以提高对该病的诊断、鉴别诊断及愈合进行评估。方法通过对43例疲劳骨折患者的X线、C T、M RI影像学资料进行对比、分析,总结疲劳骨折X线、C T、M RI的影像学表现。结果本组病例中早期仅有临床症状的病例,X线及CT检查可为阴性,中晚期病例则X线和CT 的诊断价值无差别;磁共振对疲劳骨折的敏感性、特异性较X线和CT高,特别是T2 WI STIR和DWI敏感性更高,可作为疲劳骨折的早期诊断及对其愈合进行评估。结论疲劳骨折在磁共振检查中STIR和DWI的影像学表现有较高的特异性和敏感性,可对早期疲劳骨折进行诊断、鉴别诊断和对其愈合进行评估。%Objective To discuss the diagnostic value of STIR and DWI of MRI in the earlier phase of stress fracture in order to enhance the ability of diagnosis ,differential diagnosis ,and healing evaluation to the disease .Methods We con-trast and analyze the X-ray ,CT and MRI date of 43 cases of stress fracture ,and summary the radiological manifestion . Results In these cases ,the case that has only clinical symptom in early phase is negtive in X-ray and CT examination ,and there is no different diagnostic value between X-ray and CT in the metaphase and late stage .The specificity and sensitivity of MRI to diagose the stress fracture is higher than X-ray and CT ,especially in the T2 WI STIR and DWI is much higher , and it can make the earlier diagnosis and make evaluation to the healing .Conclusion The stress fracture has high specifici-ty and sensitivity in the STIR and DWI sequences of MRI ,so it can make early diagnosis ,differential diagnosis ,and it can make proper evaluation to the healing .

  12. X-ray residual stress analysis on machined and tempered HPSN-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Immelmann, S.; Welle, E.; Reimers, W. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1997-11-15

    The residual stress state induced by grinding and tempering of hot pressed silicon nitride (HPSN) samples is studied by X-ray diffraction. The results reveal that the residual stress values at the surface of the samples as well as their gradient within the penetration depth of the X-rays depend on the sintering aid and thus, on the glassy phase content of the HPSN. Tempering of the ground HPSN reduces the residual stress values due to microplastic deformation, whereas an oxidation of the glassy phase leads to the formation of compressive residual stresses. (orig.) 35 refs.

  13. Watershed Scale Analysis of Groundwater Surface Water Interactions and Its Application to Conjunctive Management under Climatic and Anthropogenic Stresses over the US Sunbelt

    Science.gov (United States)

    Seo, Seung Beom

    Although water is one of the most essential natural resources, human activities have been exerting pressure on water resources. In order to reduce these stresses on water resources, two key issues threatening water resources sustainability - interaction between surface water and groundwater resources and groundwater withdrawal impacts of streamflow depletion - were investigated in this study. First, a systematic decomposition procedure was proposed for quantifying the errors arising from various sources in the model chain in projecting the changes in hydrologic attributes using near-term climate change projections. Apart from the unexplained changes by GCMs, the process of customizing GCM projections to watershed scale through a model chain - spatial downscaling, temporal disaggregation and hydrologic model - also introduces errors, thereby limiting the ability to explain the observed changes in hydrologic variability. Towards this, we first propose metrics for quantifying the errors arising from different steps in the model chain in explaining the observed changes in hydrologic variables (streamflow, groundwater). The proposed metrics are then evaluated using a detailed retrospective analyses in projecting the changes in streamflow and groundwater attributes in four target basins that span across a diverse hydroclimatic regimes over the US Sunbelt. Our analyses focused on quantifying the dominant sources of errors in projecting the changes in eight hydrologic variables - mean and variability of seasonal streamflow, mean and variability of 3-day peak seasonal streamflow, mean and variability of 7-day low seasonal streamflow and mean and standard deviation of groundwater depth - over four target basins using an Penn state Integrated Hydrologic Model (PIHM) between the period 1956-1980 and 1981-2005. Retrospective analyses show that small/humid (large/arid) basins show increased (reduced) uncertainty in projecting the changes in hydrologic attributes. Further

  14. Physiological response of Pichia pastoris GS115 to methanol-induced high level production of the Hepatitis B surface antigen: catabolic adaptation, stress responses, and autophagic processes

    Directory of Open Access Journals (Sweden)

    Vanz Ana Leticia

    2012-08-01

    Full Text Available Abstract Background Pichia pastoris is an established eukaryotic host for the production of recombinant proteins. Most often, protein production is under the control of the strong methanol-inducible aox1 promoter. However, detailed information about the physiological alterations in P. pastoris accompanying the shift from growth on glycerol to methanol-induced protein production under industrial relevant conditions is missing. Here, we provide an analysis of the physiological response of P. pastoris GS115 to methanol-induced high-level production of the Hepatitis B virus surface antigen (HBsAg. High product titers and the retention of the protein in the endoplasmic reticulum (ER are supposedly of major impact on the host physiology. For a more detailed understanding of the cellular response to methanol-induced HBsAg production, the time-dependent changes in the yeast proteome and ultrastructural cell morphology were analyzed during the production process. Results The shift from growth on glycerol to growth and HBsAg production on methanol was accompanied by a drastic change in the yeast proteome. In particular, enzymes from the methanol dissimilation pathway started to dominate the proteome while enzymes from the methanol assimilation pathway, e.g. the transketolase DAS1, increased only moderately. The majority of methanol was metabolized via the energy generating dissimilatory pathway leading to a corresponding increase in mitochondrial size and numbers. The methanol-metabolism related generation of reactive oxygen species induced a pronounced oxidative stress response (e.g. strong increase of the peroxiredoxin PMP20. Moreover, the accumulation of HBsAg in the ER resulted in the induction of the unfolded protein response (e.g. strong increase of the ER-resident disulfide isomerase, PDI and the ER associated degradation (ERAD pathway (e.g. increase of two cytosolic chaperones and members of the AAA ATPase superfamily indicating that potential

  15. Wall shear stress measurement in blade end-wall corner region

    Science.gov (United States)

    Bhargava, R.; Raj, R.; Boldman, D. R.

    1987-01-01

    The magnitude and the direction of wall shear stress and surface pressure in the blade end-wall corner region were investigated. The measurements were obtained on a specially designed Preston tube, the tip of which could be concentrically rotated about its axis of rotation at the measurement location. The magnitude of wall shear stress in the vicinity of the corner was observed to increase significantly (170 percent) compared to its far-upstream value; the increase was consistently higher on the blade surface compared to the value on the plate surface of the blade end-wall corner. On both surfaces in the blade end-wall corner, the variation of the wall shear stress direction was found to be more predominant in the vicinity of the blade leading-edge location. The trend of the measured wall shear stress direction showed good agreement with the limiting streamline directions obtained from the flow visualization studies.

  16. Surface microstructure and stress characteristics in pure titanium after high-current pulsed electron beam irradiation%强流脉冲电子束诱发纯钛表面的微观结构及应力状态

    Institute of Scientific and Technical Information of China (English)

    李艳; 蔡杰; 吕鹏; 邹阳; 万明珍; 彭冬晋; 顾倩倩; 关庆丰

    2012-01-01

    利用强流脉冲电子束(HCPEB)装置对金属纯钛进行轰击,采用X射线衍射,扫描电子显微镜及透射电子显微镜技术详细分析了轰击样品表层的结构和缺陷.X射线衍射分析表明,HCPEB能够在材料表层诱发幅值为GPa量级的压应力,并在(100),(102)和(103)晶面出现择优取向.表层微观结构的观察表明:HCPEB轰击后材料表层发生了马氏体相变,形成了大量的片状马氏体组织;此外,HCPEB轰击还在辐照表面诱发了强烈的塑性变形,一次轰击后,晶粒内部的塑性变形以(100)晶面的位错滑移为主,位错密度显著提高;多次轰击后,样品变形结构发生变化,变形孪晶的数量明显增多.这些变形微结构不仅影响表层的织构演化行为,而且还能细化晶粒,进而提高材料表面硬度,为HCPEB技术进行纯钛表面强化提供了一条有效的途径.%The specimens of polycrystalline pure titanium are irradiated by high-current pulsed electron beam (HCPEB). Surface microstruc- tures and defects induced by HCPEB irradiation are investigated by using X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy technique. The XRD results show that the high value of stress (GPa order) is introduced into the irradiated surface layer, and the characteristics of preferential orientations (100), (102) and (103) are present after HCPEB treatment. The surface microstructure observations indicate that martensitic transformation occurs in the irradiated surface and a large number of plate martensite structures are formed in the irradiated surface. Moreover, strong plastic deformation is triggered by HCPEB treatment. After one pulse, (100) type slip bands are formed in the interior of grain, which leads to the increase of dislocation density. After multi- pulses, deformation microstructures change significantly, and the number of deformation twins increases evidently

  17. Surface Effects on Nanoscale Gas Flows

    Science.gov (United States)

    Beskok, Ali; Barisik, Murat

    2010-11-01

    3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

  18. Rheological characteristics of soft rock structural surface

    Institute of Scientific and Technical Information of China (English)

    陈沅江; 吴超; 傅衣铭

    2008-01-01

    There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering the deformation in the starting creep phase,so that the structural surface creep usually displays the strong surface roughness effect,and so does the latter when the asperities in the coarse surface were fractured by shearing.Under the low stress condition,there are only two phases of the decelerating creep and the constant creep for the soft rock structural surface,and as the stress increases and overcomes the rubbing resistance,the accelerating creep failure of the structural surface will happen suddenly.Therefore,a multiple rheological model,which combines the nonlinear NEWTON body(NN) of a certain mass and the empirical plastic body(EM) with the classical SAINT VENANT body,NEWTON body,KELVIN body and HOOKE body,could be used to comprehensively describe the creep characteristics of the soft rock structural surface.Its mechanical parameter values will vary owing to the different surface roughness of the structural surface.The parameters of GH,GK and ηL are positively linearly correlative to the surface roughness.The surface roughness and m are negative exponential function correlation.The long-term strength τS is positively correlative to the surface roughness.

  19. Values Research

    Science.gov (United States)

    2009-10-01

    horizontal vs. vertical. • According to the theory of Planned Behavior ( Ajzen , 1988, 2002) attitude, subjective norms and perceived control...determines intention which may end in behavior . 7 Defining Human Values Cross-cultural theories on values emerged in the 80s developed by three main...attitudes with social structure. 4 Defining Human Values • According to Parsons (Parsons & Shils, 1951), values instigate behavior . • In line

  20. Stress Management: Job Stress

    Science.gov (United States)

    Healthy Lifestyle Stress management Job stress can be all-consuming — but it doesn't have to be. Address your triggers, keep perspective and ... stress triggers, it's often helpful to improve time management skills — especially if you tend to feel overwhelmed ...

  1. Biaxial stress effects on magnetization perpendicular to the stress plane

    Energy Technology Data Exchange (ETDEWEB)

    Sablik, M.J.; Kwun, H.; Burkhardt, G.L. [Southwest Research Inst., San Antonio, TX (United States); Langman, R.A. [Univ. of Tasmania, Hobart, Tasmania (Australia)

    1995-11-01

    Effects of biaxial stress in steel on magnetization in a direction normal to the stress plane were investigated both theoretically and experimentally. The two results, which agreed qualitatively, showed that the magnetization in the normal direction generally decreased with the absolute value of the sum of the two principal stresses. The implication to nondestructive measurements of biaxial stress is discussed.

  2. Childhood Stress

    Science.gov (United States)

    ... Kids to Be Smart About Social Media Childhood Stress KidsHealth > For Parents > Childhood Stress Print A A ... and feel stress to some degree. Sources of Stress Stress is a function of the demands placed ...

  3. Effects of Different pH-Values on the Nanomechanical Surface Properties of PEEK and CFR-PEEK Compared to Dental Resin-Based Materials

    Directory of Open Access Journals (Sweden)

    Shuai Gao

    2015-07-01

    Full Text Available The study determines the stability and durability of polyetheretherketone (PEEK and a carbon fiber-reinforced PEEK (CFR-PEEK with 30% short carbon fibers, a dental composite based on Bis-GMA and polymethylmethacrylate (PMMA under the influence of different pH-values of the oral environment in vitro. Nanomechanical properties were investigated by nanoindentation and nanoscratch tests before and after incubation of the specimens at 37 °C for 30 days in artificial saliva with pH-values of 3, 7 and 10, respectively. Nanoindentation and nanoscratching tests were performed using the Hysitron TI950 TriboIndenter to evaluate the reduced elastic moduli, nanohardness, viscoelasticity, friction coefficient and residual scratch profiles. After treatment, the nanomechanical properties of unfilled PEEK did not change. The reduced elastic moduli and nanohardness of the carbon fiber-reinforced PEEK increased significantly. The reduced elastic moduli and nanohardness of CHARISMA decreased. The plasticity of all materials except that of the unfilled PEEK increased. This indicates that different pH-values of the artificial saliva solutions had no obvious influences on the nanomechanical properties of the PEEK matrix. Therefore, the aging resistance of the unfilled PEEK was higher than those of other materials. It can be deduced that the PEEK matrix without filler was more stable than with filler in the nanoscale.

  4. Linoleic acid derivative DCP-LA ameliorates stress-induced depression-related behavior by promoting cell surface 5-HT1A receptor translocation, stimulating serotonin release, and inactivating GSK-3β.

    Science.gov (United States)

    Kanno, Takeshi; Tanaka, Akito; Nishizaki, Tomoyuki

    2015-04-01

    Impairment of serotonergic neurotransmission is the major factor responsible for depression and glycogen synthase kinase 3β (GSK-3β) participates in serotonergic transmission-mediated signaling networks relevant to mental illnesses. In the forced-swim test to assess depression-like behavior, the immobility time for mice with restraint stress was significantly longer than that for nonstressed control mice. Postsynaptic cell surface localization of 5-HT1A receptor, but not 5-HT2A receptor, in the hypothalamus for mice with restraint stress was significantly reduced as compared with that for control mice, which highly correlated to prolonged immobility time, i.e., depression-like behavior. The linoleic acid derivative 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) restored restraint stress-induced reduction of cell surface 5-HT1A receptor and improved depression-like behavior in mice with restraint stress. Moreover, DCP-LA stimulated serotonin release from hypothalamic slices and cancelled restraint stress-induced reduction of GSK-3β phosphorylation at Ser9. Taken together, the results of the present study indicate that DCP-LA could ameliorate depression-like behavior by promoting translocation of 5-HT1A receptor to the plasma membrane on postsynaptic cells, stimulating serotonin release, and inactivating GSK-3β.

  5. Understanding the Risk of Chloride Induced Stress Corrosion Cracking of Interim Storage Containers for the Dry Storage of Spent Nuclear Fuel: Evolution of Brine Chemistry on the Container Surface.

    Energy Technology Data Exchange (ETDEWEB)

    Enos, David; Bryan, Charles R.

    2015-10-01

    Although the susceptibility of austenitic stainless steels to chloride-induced stress corrosion cracking is well known, uncertainties exist in terms of the environmental conditions that exist on the surface of the storage containers. While a diversity of salts is present in atmospheric aerosols, many of these are not stable when placed onto a heated surface. Given that the surface temperature of any container storing spent nuclear fuel will be well above ambient, it is likely that salts deposited on its surface may decompose or degas. To characterize this effect, relevant single and multi-salt mixtures are being evaluated as a function of temperature and relative humidity to establish the rates of degassing, as well as the likely final salt and brine chemistries that will remain on the canister surface.

  6. 半椭圆表面裂纹应力强度因子公式的评估%Evaluation of the Formula of Stress Intensity Factor K1 for Semi-Elliptical Surface Crack

    Institute of Scientific and Technical Information of China (English)

    许京荆; 王志陵; 邵仁兴; 吴益敏

    2000-01-01

    The stress-intensity factor (SIF) of the semi-elliptical surface crack in the finite body under extensional stress is sclculated by using the FEM software ANSYS release 5.5. The correction factor Mf of SIF at different point along the front of the crack is determined.The relation between Mf and the semi-elliptical shape a lc, the relative crack depth a/b, the variation of angle θ, the relative crack width 2c/w and the relative height-width ratio h/w are calculated respectively. Finally the application range and the modification of the engineering formula about SIF is proposed.

  7. Assimilation of GRACE Terrestrial Water Storage into a Land Surface Model: Evaluation 1 and Potential Value for Drought Monitoring in Western and Central Europe

    Science.gov (United States)

    Li, Bailing; Rodell, Matthew; Zaitchik, Benjamin F.; Reichle, Rolf H.; Koster, Randal D.; van Dam, Tonie M.

    2012-01-01

    A land surface model s ability to simulate states (e.g., soil moisture) and fluxes (e.g., runoff) is limited by uncertainties in meteorological forcing and parameter inputs as well as inadequacies in model physics. In this study, anomalies of terrestrial water storage (TWS) observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission were assimilated into the NASA Catchment land surface model in western and central Europe for a 7-year period, using a previously developed ensemble Kalman smoother. GRACE data assimilation led to improved runoff correlations with gauge data in 17 out of 18 hydrological basins, even in basins smaller than the effective resolution of GRACE. Improvements in root zone soil moisture were less conclusive, partly due to the shortness of the in situ data record. In addition to improving temporal correlations, GRACE data assimilation also reduced increasing trends in simulated monthly TWS and runoff associated with increasing rates of precipitation. GRACE assimilated root zone soil moisture and TWS fields exhibited significant changes in their dryness rankings relative to those without data assimilation, suggesting that GRACE data assimilation could have a substantial impact on drought monitoring. Signals of drought in GRACE TWS correlated well with MODIS Normalized Difference Vegetation Index (NDVI) data in most areas. Although they detected the same droughts during warm seasons, drought signatures in GRACE derived TWS exhibited greater persistence than those in NDVI throughout all seasons, in part due to limitations associated with the seasonality of vegetation.

  8. Features of wind field over the sea surface in the coastal area

    Science.gov (United States)

    Monzikova, A. K.; Kudryavtsev, V. N.; Myasoedov, A. G.; Chapron, B.; Zilitinkevich, S. S.

    2017-01-01

    In this paper we analyze SAR wind field features, in particular the effects of wind shadowing. These effects represent the dynamics of the internal atmospheric boundary layer, which is formed due to the transition of the air flow arriving from the rough land surface to the "smooth" water surface. In the wind-shadowed area, the flow accelerates, and a surface wind stress increases with fetch. The width of the shadow depends not only on the wind speed and atmospheric boundary layer stratification, but also on geographic features such as windflow multiple transformations over the complex surface land-Lake Chudskoe-land-Gulf of Finland. Measurements showed that, in the area of wind acceleration, the surface stress normalized by an equilibrium value (far from the coast) is a universal function of dimensionless fetch Xf/G. Surface wind stress reaches an equilibrium value at Xf/G ≈ 0.4, which is the scale of the planetary-boundary-layer relaxation.

  9. Initial and delayed stress phase imaging in a single-injection double-acquisition SPECT. The potential value of early {sup 99m}Tc-MIBI redistribution in assessment of myocardial perfusion reversibility in patients with coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Beiki, D. [Research Inst. for Nuclear Medicine, Tehran Univ. of Medical Sciences, Tehran (Iran); Dept. of Nuclear Pharmacy, Tehran Univ. of Medical Sciences, Tehran (Iran); Fallahi, B.; Fard-Esfahani, A.; Eftekhari, M. [Research Inst. for Nuclear Medicine, Tehran Univ. of Medical Sciences, Tehran (Iran); Mohseni, Z.; Khalaj, A. [Dept. of Nuclear Pharmacy, Tehran Univ. of Medical Sciences, Tehran (Iran)

    2010-07-01

    Some studies reported that {sup 99m}Tc-MIBI may redistribute in ischaemic myocardium and this phenomenon may have potential role for better assessment of viability by delayed {sup 99m}Tc-MIBI imaging. Some studies also suggested that infusion of low dose dobutamine during delayed imaging may enhance the value of {sup 99m}Tc-MIBI imaging for evaluation of viability. The aim of this study is to determine whether the observed changes of perfusion defects on delayed images are caused by early radiotracer redistribution or as a result of reversal partial volume effect secondary to inotropic stimulation. Patients, methods: 89 patients with angiographically proven coronary artery disease (CAD) were enrolled in this randomized clinical trial study. In all cases, gated-SPECT images were obtained 60 minutes after stress with dipyridamole injection. Subsequently the patients were randomly allocated in two groups and the second imaging was performed at 120{sup th} minute during low dose dobutamine (dobutamine group; 45 cases) or placebo infusion (placebo group; 44 cases). Difference between summed stress score of the first (SSS{sub 1}) and second (SSS{sub 2}) stress images ({delta}SSS) was considered as a marker of reversibility in single-injection double-acquisition (SIDA) protocol. Also summed difference score (SDS) was recorded as a marker of reversibility in standard stress/rest, double-injection double-acquisition (DIDA) protocol. {delta}SSS of the two studied groups were compared. Also the correlation and agreement between {delta}SSS and SDS were analyzed. Results: A significant difference was found between SSS{sub 1} (median 15, range 0-48) and SSS{sub 2} (median 11, range 0-42) in total patients (p < 0.0001). A significant correlation was noted between {delta}SSS and SDS in dobutamine group (r = 0.58, p = 0.002) as well as in placebo group (r = 0.57, p < 0.0001). Considering DIDA protocol as a standard reference method, the influence of dobutamine infusion was not

  10. 药物负荷核素心肌灌注显影对冠心病的诊断价值%Diagnostic value of drug stress nuclide myocardial perfusion imaging to coronary heart disease

    Institute of Scientific and Technical Information of China (English)

    张海英; 郭月玲; 李菲; 蔡丽; 蒲朝煜

    2012-01-01

    Objective To explore the diagnostic value of drug stress nuclide myocardial perfusion imaging ( MPI ) to coronary heart disease ( CHD ). Methods The patients ( n = 88 ) with suspected CHD were simultaneously given coronary angiography ( CAG ) and dipyridamole or adenosine stress nuclide MPI, and then they were given retrospective analysis. The difference was less than 14 days between CAG date and MPI date. Taking CAG results as golden criterion of CHD diagnosis, the sensitivity and specificity of drug stress nuclide MPI were compared and analyzed. Results The sensitivity, specificity and accuracy of drug stress nuclide MPI were, respectively, 91. 4% ,73. 3% and 85. 2% in the diagnosis of CHD. Among 5 false negative cases ,4 with single vessel lesion, 1 with double vessel lesion and all of them had good compensatory circulation. Among 8 false positive cases, 3 with syndrome X and 4 with slow coronary flow. Conclusion Drug stress nuclide MPI is an effective pathway for non-invasive diagnosis of CHD and myocardial ischemia. Most of patients with false positive or false negative have corresponding pathophysiological bases of coronary artery or cardial myodium.%目的 探讨药物负荷核素心肌灌注显像(MPI)对冠心病的诊断价值.方法 回顾性分析88例疑有冠心病且同时行冠状动脉造影(CAG)和双嘧达莫或腺苷药物负荷核素MPI患者,CAG与MPI检查日期相差不超过14 d,以CAG检查结果作为诊断冠心病的金标准,对比分析药物负荷核素MPI敏感度、特异性等指标.结果 药物负荷核素MPI诊断冠心病的敏感度、特异性、准确率分别为91.4%、73.3%、85.2%;在5例假阴性患者中,4例为单支病变,1例为双支病变,侧支循环均良好;8例假阳性患者中,3例为X综合征,4例为冠状动脉血流缓慢.结论 药物负荷核素心肌灌注显像是无创诊断冠心病及心肌缺血的有效途径,其假阳性和假阴性患者多有相应的冠状动脉或心肌的病理生理基础.

  11. 尿中氧化应激指标作为学生体检中测定指标的意义%Value of urine oxidative stress index as a biomarker in student health examination

    Institute of Scientific and Technical Information of China (English)

    郭琪; 吕兆阳; 任艳苹; 王家仲

    2013-01-01

    [Objective] To explore the value of urine oxidative stress index as a biomarker in student health examination. [ Methods ] Through morning urine collection of 34 obesity college students with body mass index ( BMI) over 30, the urinary sodium, creatinine, oxidative stress indices (H2O2 and thiobarbituric acid reactive substances (TBARS) were determined. [Results] The urine TBARS level was significantly correlated with daily salt intake, obesity , blood pressure , blood lipids(P <0. 05). [ Conclusion] It is recommended that the urine oxidative stress index (urine TBARS excretion) as a biomarker in student health examination which can provide specific guidance in lifestyle of the student population with quantitative data basis, at the same time as a risk factor for cardiovascular disease can deepen students'understanding of cardiovascular disease hazards as quantization marker.%目的 探讨尿中氧化应激指标作为学生体检中测定指标的意义.方法 通过对体重指数(BMI)30以上的肥胖大学生34人进行晨尿采集,测定尿钠、肌酐、氧化应激指标[(H202和硫代巴比妥酸反应产物(TBARS)],观察尿中氧化应激水平和摄盐量(通过晨尿钠和肌酐公式测算)及现有体检指标(肥胖、血压、血脂等)的关系.结果 尿中TBARS排泄量和日食盐摄入量、肥胖、血压、血脂之间有统计学意义的相关性(P<0.05).结论 建议学生体检中增加尿中TBARS排泄量测定,可以为学生人群的具体生活方式的指导提供量化的数据依据,同时作为一个心血管疾病的危险因子可以加深学生对心血管等疾病危害性的量化认识.

  12. [Fasciocutaneous flap of the posterior surface of the thigh with distal pedicle. Anatomical study and surgical value. A propos of 3 cases].

    Science.gov (United States)

    Lambert, F; Cariou, J L; Couturaud, B; Bellavoir, A

    1996-04-01

    In the light of previous studies, the authors conducted an anatomical study on 21 cadaveric dissections with injection in order to define the characteristics of the distally based fasciocutaneous flap of the posterior surface of the thigh, described for the first time in 1988 by Maruyama. This leaf-shaped flap extends from the popliteal region to the gluteal sulcus. It possesses an axial arterial network derived from the popliteal artery, reinforced by the perforating arteries derived from the vessel or the profunda femoris artery. The venous return is ensured by venae comitantes and the communicating saphenous vein. The flap raising technique is described. From 1991 to 1994, 3 patients were operated in order to cover a defect of the knee (1 case) and amputation stumps (2 cases). The postoperative course was uneventful and the results were considered to be stable and of excellent quality with a follow-up of 2 to 4 years.

  13. Residual stress in nano-structured stainless steel (AISI 316L) prompted by Xe+ ion bombardment at different impinging angles

    Science.gov (United States)

    Cucatti, S.; Droppa, R.; Figueroa, C. A.; Klaus, M.; Genzel, Ch.; Alvarez, F.

    2016-10-01

    The effect of low energy (316L steel) is reported. The results take into account the influence of the ion incident angle maintaining constant all other bombarding parameters (i.e., ion energy and current density, temperature, and doses). The bombarded surface topography shows that ions prompt the formation of nanometric regular patterns on the surface crystalline grains and stressing the structure. The paper focalizes on the study of the surface residual stress state stemming from the ion bombardment studied by means of the "sin2 ψ" and "Universal Plot" methods. The analysis shows the absence of shear stress in the affected material region and the presence of compressive in-plane residual biaxial stress (˜200 MPa) expanding up to ˜1 μm depth for all the studied samples. Samples under oblique bombardment present higher compressive stress values in the direction of the projected ion beam on the bombarded surface. The absolute value of the biaxial surface stress difference (σ11-σ22) increases on ion impinging angles, a phenomenon associated with the momentum transfer by the ions. The highest stress level was measured for ion impinging angles of 45° ( σ 11 = -380 ± 10 MPa and σ 22 = -320 ± 10 MPa). The different stresses obtained in the studied samples do not affect significantly the formation of characteristic surface patterns.

  14. Study on the Surface Correction for the Mold of Stress Relaxation-forming%应力松弛成形模具型面修正的方法研究

    Institute of Scientific and Technical Information of China (English)

    甘忠;