WorldWideScience

Sample records for tension effectively induces

  1. Effects of tension on vortex-induced vibration (VIV) responses of a long tensioned cylinder in uniform flows

    Science.gov (United States)

    Kang, Ling; Ge, Fei; Wu, Xiaodong; Hong, Youshi

    2017-02-01

    The effects of tension on vortex-induced vibration (VIV) responses for a tension-dominated long cylinder with an aspect ratio of 550 in uniform flows are experimentally investigated in this paper. The results show that elevated tension suppresses fluctuations of maximum displacement with respect to flow velocity and makes chaotic VIV more likely to appear. With respect to periodic VIV, if elevated tension is applied, the dominant vibration frequency in the in-line (IL) direction will switch from a fundamental vibration frequency to twice the value of the fundamental vibration frequency, which results in a ratio of the dominant vibration frequency in the IL direction to that in the cross-flow direction of 2.0. The suppression of the elevated tension in the fluctuation of the maximum displacement causes the axial tension to become an active control parameter for the VIV maximum displacement of a tension-dominated long riser or tether of an engineering structure in deep oceans. However, the axial tension must be optimized before being used since the high dominant vibration frequency due to the elevated tension may unfavorably affect the fatigue life of the riser or tether.

  2. Effects of Induced Surface Tension in Nuclear and Hadron Matter

    Directory of Open Access Journals (Sweden)

    Sagun V.V.

    2017-01-01

    Full Text Available Short range particle repulsion is rather important property of the hadronic and nuclear matter equations of state. We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard-core repulsion. In addition to the hard-core repulsion taken into account by the proper volumes of particles, this equation of state explicitly contains the surface tension which is induced by another part of the hard-core repulsion between particles. At high densities the induced surface tension vanishes and the excluded volume treatment of hard-core repulsion is switched to its proper volume treatment. Possible applications of this equation of state to a description of hadronic multiplicities measured in A+A collisions, to an investigation of the nuclear matter phase diagram properties and to the neutron star interior modeling are discussed.

  3. Surface Tension Gradients Induced by Temperature: The Thermal Marangoni Effect

    Science.gov (United States)

    Gugliotti, Marcos; Baptisto, Mauricio S.; Politi, Mario J.

    2004-01-01

    Surface tensions gradients were generated in a thin liquid film because of the local increase in temperature, for demonstration purposes. This is performed using a simple experiment and allows different alternatives for heat generation to be used.

  4. Effects of internal pressure and surface tension on the growth-induced wrinkling of mucosae.

    Science.gov (United States)

    Xie, Wei-Hua; Li, Bo; Cao, Yan-Ping; Feng, Xi-Qiao

    2014-01-01

    Surface wrinkling of mucosae is crucial for the biological functions of many living tissues. In this paper, we investigate the instability of a cylindrical tube consisting of a mucosal layer and a submucosal layer. Our attention is focused on the effects of internal pressure and surface tension on the critical condition and mode number of surface wrinkling induced by tissue growth. It is found that the internal pressure plays a stabilizing role but basically has no effect on the critical mode number. Surface tension also stabilizes the system and reduces the critical mode number of surface patterns. Besides, the thinner the mucosal layer, the more significant the effect of surface tension. This work may help gain insights into the surface wrinkling and morphological evolution of such tubular organs as airways and esophagi. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. DHP-derivative and low oxygen tension effectively induces human adipose stromal cell reprogramming.

    Directory of Open Access Journals (Sweden)

    Min Ki Jee

    Full Text Available BACKGROUND AND METHODS: In this study, we utilized a combination of low oxygen tension and a novel anti-oxidant, 4-(3,4-dihydroxy-phenyl-derivative (DHP-d to directly induce adipose tissue stromal cells (ATSC to de-differentiate into more primitive stem cells. De-differentiated ATSCs was overexpress stemness genes, Rex-1, Oct-4, Sox-2, and Nanog. Additionally, demethylation of the regulatory regions of Rex-1, stemnesses, and HIF1alpha and scavenging of reactive oxygen species were finally resulted in an improved stem cell behavior of de-differentiate ATSC (de-ATSC. Proliferation activity of ATSCs after dedifferentiation was induced by REX1, Oct4, and JAK/STAT3 directly or indirectly. De-ATSCs showed increased migration activity that mediated by P38/JUNK and ERK phosphorylation. Moreover, regenerative efficacy of de-ATSC engrafted spinal cord-injured rats and chemical-induced diabetes animals were significantly restored their functions. CONCLUSIONS/SIGNIFICANCE: Our stem cell remodeling system may provide a good model which would provide insight into the molecular mechanisms underlying ATSC proliferation and transdifferentiation. Also, these multipotent stem cells can be harvested may provide us with a valuable reservoir of primitive and autologous stem cells for use in a broad spectrum of regenerative cell-based disease therapy.

  6. Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

    DEFF Research Database (Denmark)

    Balle, S S; Magnusson, S P; McHugh, M P

    2015-01-01

    The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength...... loss compared with SS. These results support the use of SS for stretching the hamstrings....

  7. Effects of electroacupuncture at different points on colorectal distention-induced changes in blood pressure, electrogastrogram, gastric tension and gastric blood flow.

    Science.gov (United States)

    Chen, Shu-Ping; Gao, Yong-Hui; Wang, Jun-Ying; Liu, Jun-Ling

    2011-12-01

    To investigate the specificity of the effects of electroacupuncture (EA) at different acupoints on gastric functional activity and gastric blood flow after colorectal distension (CRD) in the rat. Fifty Wistar rats were randomly divided into 5 groups: a control group, a Zusanli group, a non-point group, a Taichong group and a Neiguan group. Rats were anesthetized after 18 h of fasting, and a rat model of nociceptive blood pressure elevation and abnormal electrogastrogram (EGG) and gastric tension (GT) was prepared by gasbag-induced CRD. EA was given bilaterally, and its effects on gastric blood flow (GBF) of the arcus vasculosi of the greater omentum, blood pressure, EGG fast wave properties, and gastric smooth muscle tension (GT) were quantified. CRD induced an increase in blood pressure that was significantly inhibited by EA at all points (all P waves (all P wave amplitude, GT, and GBF were superior in the Zusanli group compared to the Taichong group, Neiguan group, and the non-point group. EA significantly counteracted CRD-induced changes in blood pressure, GBF, EGG, and GT. The effects of stimulation at Zusanli (ST 36) were significantly greater compared to other points, indicating relative specificity of this acupoint.

  8. Effect of Gravity on Surface Tension

    Science.gov (United States)

    Weislogel, M. M.; Azzam, M. O. J.; Mann, J. A.

    1998-01-01

    Spectroscopic measurements of liquid-vapor interfaces are made in +/- 1-g environments to note the effect of gravity on surface tension. A slight increase is detected at -1-g0, but is arguably within the uncertainty of the measurement technique. An increased dependence of surface tension on the orientation and magnitude of the gravitational vector is anticipated as the critical point is approached.

  9. Effects of eugenol on resting tension of rat atria

    Directory of Open Access Journals (Sweden)

    R.R. Olivoto

    2014-04-01

    Full Text Available In cardiac and skeletal muscle, eugenol (μM range blocks excitation-contraction coupling. In skeletal muscle, however, larger doses of eugenol (mM range induce calcium release from the sarcoplasmic reticulum. The effects of eugenol are therefore dependent on its concentration. In this study, we evaluated the effects of eugenol on the contractility of isolated, quiescent atrial trabeculae from male Wistar rats (250-300 g; n=131 and measured atrial ATP content. Eugenol (1, 3, 5, 7, and 10 mM increased resting tension in a dose-dependent manner. Ryanodine [100 µM; a specific ryanodine receptor (RyR blocker] and procaine (30 mM; a nonspecific RyR blocker did not block the increased resting tension induced by eugenol regardless of whether extracellular calcium was present. The myosin-specific inhibitor 2,3-butanedione monoxime (BDM, however, reversed the increase in resting tension induced by eugenol. In Triton-skinned atrial trabeculae, in which all membranes were solubilized, eugenol did not change resting tension, maximum force produced, or the force vs pCa relationship (pCa=-log [Ca2+]. Given that eugenol reduced ATP concentration, the increase in resting tension observed in this study may have resulted from cooperative activation of cardiac thin filaments by strongly attached cross-bridges (rigor state.

  10. Effects of eugenol on resting tension of rat atria.

    Science.gov (United States)

    Olivoto, R R; Damiani, C E N; Kassouf Silva, I; Lofrano-Alves, M S; Oliveira, M A; Fogaça, R T H

    2014-04-01

    In cardiac and skeletal muscle, eugenol (μM range) blocks excitation-contraction coupling. In skeletal muscle, however, larger doses of eugenol (mM range) induce calcium release from the sarcoplasmic reticulum. The effects of eugenol are therefore dependent on its concentration. In this study, we evaluated the effects of eugenol on the contractility of isolated, quiescent atrial trabeculae from male Wistar rats (250-300 g; n=131) and measured atrial ATP content. Eugenol (1, 3, 5, 7, and 10 mM) increased resting tension in a dose-dependent manner. Ryanodine [100 µM; a specific ryanodine receptor (RyR) blocker] and procaine (30 mM; a nonspecific RyR blocker) did not block the increased resting tension induced by eugenol regardless of whether extracellular calcium was present. The myosin-specific inhibitor 2,3-butanedione monoxime (BDM), however, reversed the increase in resting tension induced by eugenol. In Triton-skinned atrial trabeculae, in which all membranes were solubilized, eugenol did not change resting tension, maximum force produced, or the force vs pCa relationship (pCa=-log [Ca2+]). Given that eugenol reduced ATP concentration, the increase in resting tension observed in this study may have resulted from cooperative activation of cardiac thin filaments by strongly attached cross-bridges (rigor state).

  11. The Jones-Ray effect reinterpreted: Surface tension minima of low ionic strength electrolyte solutions are caused by electric field induced water-water correlations

    Science.gov (United States)

    Okur, H. I.; Chen, Y.; Wilkins, D. M.; Roke, S.

    2017-09-01

    The surface tension of electrolyte solutions exhibits a minimum at millimolar electrolyte concentrations and then rises with increasing concentration. This minimum, known as the Jones-Ray effect, has been hotly debated over the past ∼80 years. If not considered as an artifact, it is typically ascribed to a phenomenological rare binding site for ions or ion pairs. Here, we propose an alternative underlying mechanism, namely that the hydrogen bond network of water responds to the collective electrostatic field of ions by increasing its orientational order, supported by recent surface tension measurements of NaCl solutions in H2O and D2O, and second harmonic scattering experiments in combination with ion resonant second harmonic reflection experiments. Recent thermodynamic and purely electrostatic treatments of the surface tension provide support for this interpretation. In addition, concerns related to possible artifacts influencing the measurements are quantified experimentally.

  12. Dissipative Particle Dynamics of tension-induced membrane fusion

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2009-01-01

    Recent studies of tension-induced membrane fusion using dissipative particle dynamics (DPD) simulations are briefly reviewed. The stochastic nature of the fusion process makes it necessary to simulate a large number of fusion attempts in order to obtain reliable fusion statistics and to extract...

  13. Growth Factors and Tension-Induced Skeletal Muscle Growth

    Science.gov (United States)

    Vandenburgh, Herman H.

    1994-01-01

    have performed experiments to determine whether mechanical stimulation of cultured avian muscle cells alters their response to anabolic steroids or glucocorticoids. In static cultures, testosterone had no effect on muscle cell growth, but 5alpha-dihydrotestosterone and the synthetic steroid stanozolol increased cell growth by up to 18% and 30%, respectively, after a three day exposure. We completed development of a new IBM-based mechanical cell stimulator system to provide greater flexibility in operating and monitoring our experiments. Our previous long term studies on myofiber growth were designed around a perfusion system of our own design. We have recently changed to performing these studies using a modified CELLCO cartridge bioreactor system Z since it has been certified as the ground-based model for the Shuttle's Space Tissue Loss (STL) F= Cell Culture Module. The current goals of this aspect of the project are three fold: 1) to design a Z cell culture system for studying avian skeletal myofiber atrophy on the Shuttle and Space Station; 0 2) to expand the use of bioreactors to cells which do not grow in either suspension or attached to the hollow fibers; and 3) to combine the bioreactor system with our computerized mechanical cell stimulator to have a better in vitro model to study tension/gravity/stretch regulation of skeletal muscle size. Preliminary studies also reported on involved : (1) how release of tension can induce rapid atrophy of tissues cultured avian skeletal muscle cells, and (2) a mechanism to transfer and maintain avian skeletal muscle organoids in modified cartridges in the Space Tissue Loss Module.

  14. The effect of vesicle shape, line tension, and lateral tension on membrane-binding proteins

    Science.gov (United States)

    Hutchison, Jaime B.

    Model membranes allow for the exploration of complex biological phenomena with simple, controllable components. In this thesis we employ model membranes to determine the effect of vesicle properties such as line tension, lateral tension, and shape on membrane-binding proteins. We find that line tension at the boundary between domains in a phase separated vesicle can accumulate model membrane-binding proteins (green fluorescent protein with a histidine tag), and that those proteins can, in turn, alter vesicle shape. These results suggest that domains in biological membranes may enhance the local concentration of membrane-bound proteins and thus alter protein function. We also explore how membrane mechanical and chemical properties alter the function of the N-BAR domain of amphiphysin, a membrane-binding protein implicated in endocytosis. We find that negatively charged lipids are necessary for N-BAR binding to membranes at detectable levels, and that, at least for some lipid species, binding may be cooperative. Measurements of N-BAR binding as a function of vesicle tension reveal that modest membrane tension of around 2 mN/m, corresponding to a strain of around 1%, strongly increases N-BAR binding. We attribute this increase in binding with tension to the insertion of N-BAR's N-terminal amphipathic helix into the membrane which increases the membrane area. We propose that N-BAR, which was previously described as being able to sense membrane curvature, may be sensing strain instead. Measurements of membrane deformation by N-BAR as a function of membrane tension reveal that tension can hinder membrane deformation. Thus, tension may favor N-BAR binding yet suppress membrane deformation/tubulation, which requires work against tension. These results suggest that membrane tension, a parameter that is often not controlled in model membranes but is tightly controlled in biological cells, may be important in regulating protein binding and assembly and, hence, protein

  15. Spontaneous Pattern Formation Induced by Bénard-Marangoni Convection for Sol-Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility.

    Science.gov (United States)

    Uchiyama, Hiroaki; Matsui, Tadayuki; Kozuka, Hiromitsu

    2015-11-17

    Evaporation-driven surface tension gradient in the liquid layer often causes the convective flow, i.e., Bénard-Marangoni convection, resulting in the formation of cell-like patterns on the surface. Here, we prepared sol-gel-derived titania films from Ti(OC3H7(i))4 solutions by dip coating and discussed the effect of the addition of co-solvents with a high surface tension and low volatility on the spontaneous pattern formation induced by Bénard-Marangoni convection. Propylene glycol (PG, with a surface tension of 38.6 mN m(-1)) and dipropylene glycol (DPG, with a surface tension of 33.9 mN m(-1)) were added to the coating solutions containing 2-propanol (2-Pr, with a surface tension of 22.9 mN m(-1)) for controlling the evaporation-driven surface tension gradient in the coating layer on a substrate. During dip coating at a substrate withdrawal speed of 50 cm min(-1) in a thermostatic oven at 60 °C, linearly arranged cell-like patterns on a micrometer scale were spontaneously formed on the titania gel films, irrespective of the composition of coating solutions. Such surface patterns remained even after the heat treatment at 200 and 600 °C, where the densification and crystallization of the titania films progressed. The width and height of the cell-like patterns increased with increasing PG and DPG contents in the coating solutions, where the addition of PG resulted in the formation of cells with a larger height than DPG.

  16. Lateral Tension-Induced Penetration of Particles into a Liposome

    Directory of Open Access Journals (Sweden)

    Kazuki Shigyou

    2017-07-01

    Full Text Available It is important that we understand the mechanism of the penetration of particles into a living cell to achieve advances in bionanotechnology, such as for treatment, visualization within a cell, and genetic modification. Although there have been many studies on the application of functional particles to cells, the basic mechanism of penetration across a biological membrane is still poorly understood. Here we used a model membrane system to demonstrate that lateral membrane tension drives particle penetration across a lipid bilayer. After the application of osmotic pressure, fully wrapped particles on a liposome surface were found to enter the liposome. We discuss the mechanism of the tension-induced penetration in terms of narrow constriction of the membrane at the neck part. The present findings are expected to provide insight into the application of particles to biological systems.

  17. Growth factor involvement in tension-induced skeletal muscle growth

    Science.gov (United States)

    Vandenburgh, Herman H.

    1993-01-01

    Long-term manned space travel will require a better understanding of skeletal muscle atrophy which results from microgravity. Astronaut strength and dexterity must be maintained for normal mission operations and for emergency situations. Although exercise in space slows the rate of muscle loss, it does not prevent it. A biochemical understanding of how gravity/tension/exercise help to maintain muscle size by altering protein synthesis and/or degradation rate should ultimately allow pharmacological intervention to prevent muscle atrophy in microgravity. The overall objective is to examine some of the basic biochemical processes involved in tension-induced muscle growth. With an experimental in vitro system, the role of exogenous and endogenous muscle growth factors in mechanically stimulated muscle growth are examined. Differentiated avian skeletal myofibers can be 'exercised' in tissue culture using a newly developed dynamic mechanical cell stimulator device which simulates different muscle activity patterns. Patterns of mechanical activity which significantly affect muscle growth and metabolic characteristics were found. Both exogenous and endogenous growth factors are essential for tension-induced muscle growth. Exogenous growth factors found in serum, such as insulin, insulin-like growth factors, and steroids, are important regulators of muscle protein turnover rates and mechanically-induced muscle growth. Endogenous growth factors are synthesized and released into the culture medium when muscle cells are mechanically stimulated. At least one family of mechanically induced endogenous factors, the prostaglandins, help to regulate the rates of protein turnover in muscle cells. Endogenously synthesized IGF-1 is another. The interaction of muscle mechanical activity and these growth factors in the regulation of muscle protein turnover rates with our in vitro model system is studied.

  18. Effect of respiratory physiotherapy on arterial oxygen tension.

    Science.gov (United States)

    Hedstrand, U; Liw, M; Rooth, G; Ogren, C H

    1978-01-01

    The effect of deep breathing on arterial oxygen tension was investigated in 45 postoperative patients. Arterial oxygen tension was estimated by the transcutaneous oxygen tension method, which allows continuous non-invasive measurement of the arterial oxygen tension changes. Three deep breaths in 1 min, assisted by three respiratory therapy devices, were compared to a standard physiotherapy programme. A peak increase in arterial oxygen tension of 3--4.5 mmHg occurred after 1 min, and significantly increased values were seen for 2--4 min following deep breathing with the three respiratory devices. From the various physiotherapeutic procedures, verbally and manually assisted deep breathing gave a 7 mmHg PO2 peak and significantly increased values for 6 min. The sign mechanism is discussed in the light of the present knowledge of airway closure, which gives a satisfactory explanation of the short-lasting increase in oxygen tension.

  19. Effects of 1,3-dimethyl-5-aminoadamantane hydrochloride (DMAA) on the stretch-induced reflex tension of flexor muscles and the excitability of the gamma-loop in decerebrate and spinal cats.

    Science.gov (United States)

    Wand, P; Sontag, K H; Cremer, H

    1977-07-01

    The effects of 10 mg/kg i.v. 1,3-dimethyl-5-aminoadamantane hydrochloride (memantine, DMAA) on the stretch-induced reflex tension of flexor muscles extensor digitorum longus and tibialis anterior (EDL/TA) and on the excitability of the neurons relaying transmission in the gamma-loop have been investigated in decerebrate and spinal cats. DMAA essentially reduced the relfex excitability of flexors EDL/TA induced by fusimotor activity in the decerebrate preparation. The drug did not stimulate the reflex activity in acute spinal cats. In the concentration used, DMAA suppressed largely the transmission of the fusimotor reflex in the decerebrate as well as in the spinal preparation, although in spinal cats DMAA increased the average firing rate of muscle spindle primaries originating from EDL/TA muscles. The possible mechanism of action of the compound on dopaminergic and serotonergic systems as well as its basic effects on neuronal membranes is discussed.

  20. The effects of ambient impurities on the surface tension

    OpenAIRE

    Ponce-Torres A.; Vega E. J.

    2016-01-01

    A liquid bridge is a liquid column held captive between two coaxial and parallel solid disks. It is an excellent test bench where measuring the surface tension. In this paper, we used this fluid configuration to examine experimentally the effects of ambient impurities on the surface tension over time. For this purpose, the liquid bridge equilibrium shape was analyzed when the liquid bridge was surrounded by three environments: the uncontrolled ambient, and both air and argon encapsulated in a...

  1. The effects of ambient impurities on the surface tension

    Directory of Open Access Journals (Sweden)

    Ponce-Torres A.

    2016-01-01

    Full Text Available A liquid bridge is a liquid column held captive between two coaxial and parallel solid disks. It is an excellent test bench where measuring the surface tension. In this paper, we used this fluid configuration to examine experimentally the effects of ambient impurities on the surface tension over time. For this purpose, the liquid bridge equilibrium shape was analyzed when the liquid bridge was surrounded by three environments: the uncontrolled ambient, and both air and argon encapsulated in a small glass cover. Ambient contamination produced a sharp decrease of the surface tension of ultra-pure water. The presence of an anionic surfactant in the free surface of an aqueous solution did not inhibit the action of impurities coming from the ambient. Impurities can influence the dynamical behavior of the free surface in flows dominated by the surface tension. Therefore, a careful control of that influence can be crucial in many applications of fluid mechanics.

  2. Mapping surface tension induced menisci with application to tensiometry and refractometry.

    Science.gov (United States)

    Mishra, Avanish; Kulkarni, Varun; Khor, Jian-Wei; Wereley, Steve

    2015-07-28

    In this work, we discuss an optical method for measuring surface tension induced menisci. The principle of measurement is based upon the change in the background pattern produced by the curvature of the meniscus acting as a lens. We measure the meniscus profile over an inclined glass plate and utilize the measured meniscus for estimation of surface tension and refractive index.

  3. Effect of surface tension on the onset of convection in a double-diffusive layer

    Science.gov (United States)

    Chen, C. F.; Su, T. F.

    1992-01-01

    The effect of surface tension on the stability of a double-diffusive layer is considered using linear stability analysis. The surface tension is assumed to vary linearly with temperature and solute concentration. The eigenvalue problem is solved by the Galerkin method. Results show that the predicted stability boundary based on Marangoni effects alone is completely altered in the presence of buoyancy effects induced by low gravity levels (about 10 exp -5 g). At reduced gravity levels, salt-finger instability may onset in the overstable mode due to the stabilizing effect of surface tension. Fluid properties in terms of the Prandtl and the Lewis numbers have a profound effect on the stability conditions; opposite stability characteristics are found in salt solutions and in molten metals.

  4. Surface tension alteration on calcite, induced by ion substitution

    DEFF Research Database (Denmark)

    Sakuma, Hiroshi; Andersson, Martin Peter; Bechgaard, Klaus

    2014-01-01

    The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale...... in the pore water. Incorporation of MgSO4 into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds......., where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg2+ and SO4 2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg2+ substitution for Ca2+ is favored but only when SO4 2- is also present and MgSO4 incorporates...

  5. Tension-induced vesicle fusion: pathways and pore dynamics

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2008-01-01

    and eventually opens a pore to complete the fusion process. In pathway II, at higher tension, a stalk is formed during the fusion process that is then transformed by transmembrane pore formation into a fusion pore. Whereas the latter pathway II resembles stalk pathways as observed in other simulation studies......, fusion pathway I, which does not involve any stalk formation, has not been described previously to the best of our knowledge. A statistical analysis of the various processes shows that fusion is the dominant pathway for releasing the tension of the vesicles. The functional dependence of the observed...

  6. Tension induced phase transitions in biomimetic fluid membranes

    Science.gov (United States)

    Shapiro, Marc; Vlahovska, Petia

    2012-11-01

    Membranes in eukaryotic cells are mixtures of hundreds of lipid species. The lipid diversity enables membranes to phase separate and form domains, called rafts, which play a critical role in cell functions such as signaling and trafficking. The phase transitions underlying raft formation have been extensively studied as a function of temperature and composition. However, the third dimension of the phase diagram, i.e., the tension (2D pressure), is still unexplored because membrane tension is difficult to control and quantify. To overcome this challenge, we develop two approaches, capillary micromechanics and electrodeformation, in which the tension is regulated by the area dilation accompanying deformation of a vesicle (a closed membrane). The first technique consists of forcing an initially quasi-spherical vesicle through a tapered glass microcapillary, while the second method utilizes uniform electric fields to deform the vesicle into an ellipsoid. Domains are visualized using a fluorescent dye, which preferentially partitions in one of the phases. The experimental results suggest that the miscibility temperature (at which domains form in an initially homogeneous membrane) increases with applied tension. Domain motions and coarsening are also investigated.

  7. Size effect in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars

    1999-01-01

    The strength in tension perpendicular to the grain is known to decrease with an increase in the stressed volume. Usually this size effect is explained on a stochastic basis, that is an explanation relying on an increased probability of encountering a strength reducing flaw when the volume...

  8. Plasticity size effects in tension and compression of single crystals

    NARCIS (Netherlands)

    Deshpande, VS; Needleman, A; Van der Giessen, E

    2005-01-01

    The effect of size and loading conditions on the tension and compression stress-strain response of micron-sized planar crystals is investigated using discrete dislocation plasticity. The crystals are taken to have a single active slip system and both small-strain and finite-strain analyses are

  9. Multi-phase-field method for surface tension induced elasticity

    Science.gov (United States)

    Schiedung, Raphael; Steinbach, Ingo; Varnik, Fathollah

    2018-01-01

    A method, based on the multi-phase-field framework, is proposed that adequately accounts for the effects of a coupling between surface free energy and elastic deformation in solids. The method is validated via a number of analytically solvable problems. In addition to stress states at mechanical equilibrium in complex geometries, the underlying multi-phase-field framework naturally allows us to account for the influence of surface energy induced stresses on phase transformation kinetics. This issue, which is of fundamental importance on the nanoscale, is demonstrated in the limit of fast diffusion for a solid sphere, which melts due to the well-known Gibbs-Thompson effect. This melting process is slowed down when coupled to surface energy induced elastic deformation.

  10. EFFECT OF KAYAK ERGOMETER ELASTIC TENSION ON UPPER LIMB EMG ACTIVITY AND 3D KINEMATICS

    Directory of Open Access Journals (Sweden)

    Neil Fleming

    2012-09-01

    Full Text Available Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10 performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001, no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD activity in the latter stages (70 to 90% of the cycle (p < 0.05. No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7° occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05. In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces

  11. Tension-induced fusion of bilayer membranes and vesicles

    Science.gov (United States)

    Shillcock, Julian C.; Lipowsky, Reinhard

    2005-03-01

    Maintaining the integrity of their protective plasma membrane is a primary requirement of cells. Accordingly, cellular events that breach the membrane are tightly regulated. Artificial vesicles used in drug delivery must also stay intact until they have reached the desired target. In both cases, the intrinsic resistance of the membrane to rupture must be overcome to allow the efflux of the vesicle's contents. Here, we use mesoscopic simulations to study the fusion of 28-nm-diameter vesicles to 50 × 50 nm2 planar membrane patches over 2 μs. We monitor the time evolution of 93 different fusion attempts. This allows us to construct a global morphology diagram, using the initial tensions of the vesicle and the planar membrane patch as control parameters, and to determine the corresponding fusion statistics. All successful fusion events are observed to occur within 350 ns, which reflects the presence of alternative pathways for the tension relaxation.

  12. Size Effect in Tension Perpendicular to Grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Clorius, Christian Odin; Hoffmeyer, Preben

    2004-01-01

    The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents a hypothesis where ...

  13. MIGRAIN AND TENSION TYPE HEADACHE IN CHILDREN: THE APPROACH TO EFFECTIVE TREATMENT. PART 1

    Directory of Open Access Journals (Sweden)

    A. V. Sergeev

    2012-01-01

    Full Text Available Headache is one of the most common complaints of children and adolescents. The most often causes of cephalgia in children are primary headaches (mainly migraine and tension-type headache. Recently there has been a significant increase in prevalence of primary headaches, which can be due to the changes of children’s way of life. The lack of the strict recommendations on symptomatic and preventive treatment of primary headaches in children in Russia often leads to erroneous indications. Inappropriate treatment can result in migraine and tension-type headache course aggravation with the formation of chronic daily headache, development of medicine-induced headache and other undesirable side-effects. The literature review covers the questions of therapy of the main forms of primary headaches in children: migraines and tension-type headaches. In the first part of the article the issues of diagnostics, algorithm of treatment and non-medicinal methods of treatment of headaches are discussed.

  14. Communication: Activation energy of tension-induced pore formation in lipid membranes.

    Science.gov (United States)

    Karal, Mohammad Abu Sayem; Yamazaki, Masahito

    2015-08-28

    Tension plays a vital role in pore formation in biomembranes, but the mechanism of pore formation remains unclear. We investigated the temperature dependence of the rate constant of constant tension (σ)-induced pore formation in giant unilamellar vesicles of lipid membranes using an experimental method we developed. By analyzing this result, we determined the activation energy (Ua) of tension-induced pore formation as a function of tension. A constant (U0) that does not depend on tension was found to contribute significantly to Ua. Analysis of the activation energy clearly indicated that the dependence of Ua on σ in the classical theory is correct, but that the classical theory of pore formation is not entirely correct due to the presence of U0. We can reasonably consider that U0 is a nucleation free energy to form a hydrophilic pre-pore from a hydrophobic pre-pore or a region with lower lateral lipid density. After obtaining U0, the evolution of a pre-pore follows a classical theory. Our data provide valuable information that help explain the mechanism of tension-induced pore formation in biomembranes and lipid membranes.

  15. Effects of hydrogen sulfide on the expression of alkaline phosphatase, osteocalcin and collagen type I in human periodontal ligament cells induced by tension force stimulation

    National Research Council Canada - National Science Library

    Qin, Jing; Hua, Yongmei

    2016-01-01

    .... The aim of the present study was to investigate the effects of hydrogen sulfide (H2S) on periodontal tissue remodeling by examining the mRNA and protein expression levels of alkaline phosphatase (ALP), osteocalcin (OCN...

  16. Surface Tension

    Science.gov (United States)

    Theissen, David B.; Man, Kin F.

    1996-01-01

    The effect of surface tension is observed inmany everyday situations. For example, a slowly leaking faucet drips because the force surface tension allows the water to cling to it until a sufficient mass of water is accumulated to break free.

  17. Low oxygen tension increased fibronectin fragment induced catabolic activities--response prevented with biomechanical signals.

    Science.gov (United States)

    Parker, Eleanor; Vessillier, Sandrine; Pingguan-Murphy, Belinda; Abas, Wan; Bader, Dan L; Chowdhury, Tina T

    2013-10-25

    The inherent low oxygen tension in normal cartilage has implications on inflammatory conditions associated with osteoarthritis (OA). Biomechanical signals will additionally contribute to changes in tissue remodelling and influence the inflammatory response. In this study, we investigated the combined effects of oxygen tension and fibronectin fragment (FN-f) on the inflammatory response of chondrocytes subjected to biomechanical signals. Chondrocytes were cultured under free-swelling conditions at 1%, 5% and 21% oxygen tension or subjected to dynamic compression in an ex vivo 3D/bioreactor model with 29 kDa FN-f, interleukin-1beta (IL-1β) and/or the nitric oxide synthase (NOS) inhibitor for 6 and 48 hours. Markers for catabolic activity (NO, PGE2), tissue remodelling (GAG, MMPs) and cytokines (IL-1β, IL-6 and TNFα) were quantified by biochemical assay. Aggrecan, collagen type II, iNOS and COX-2 gene expression were examined by real-time quantitative PCR. Two-way ANOVA and a post hoc Bonferroni-corrected t-test were used to analyse data. Both FN-fs and IL-1β increased NO, PGE2 and MMP production (all Ptreatment with FN-f or IL-1β increased iNOS and COX-2 expression and reduced aggrecan and collagen type II (all P signals abolished catabolic activities in an oxygen-independent manner and NOS inhibitors supported loading-induced recovery resulting in reparative activities. Future investigations will utilize the ex vivo model as a tool to identify key targets and therapeutics for OA treatments.

  18. Perceiving the affordance of string tension for power strokes in badminton: expertise allows effective use of all string tensions.

    Science.gov (United States)

    Zhu, Qin

    2013-01-01

    Affordances mean opportunities for action. These affordances are important for sports performance and relevant to the abilities developed by skilled athletes. In racquet sports such as badminton, different players prefer widely different string tension because it is believed to provide opportunities for effective strokes. The current study examined whether badminton players can perceive the affordance of string tension for power strokes and whether the perception of affordance itself changed as a function of skill level. The results showed that string tension constrained the striking performance of both novice and recreational players, but not of expert players. When perceptual capability was assessed, perceptual mode did not affect perception of the optimal string tension. Skilled players successfully perceived the affordance of string tension, but only experts were concerned about saving energy. Our findings demonstrated that perception of the affordance of string tension in badminton was determined by action abilities. Furthermore, experts could adjust the action to maintain a superior level of performance based on the perception of affordance.

  19. Selective surface tension induced patterning on flexible textiles via click chemistry.

    Science.gov (United States)

    Wang, Ben; Zhang, Yabin; Zhang, Li

    2017-04-06

    A solid surface commonly forms two wetting modes by alternating the type of the liquids, i.e. wetting and nonwetting. Here we report that a textile can be programmed to exhibit three wetting modes by simply alternating the surface tension of the liquids, they are in turn, wetting, selective wetting and nonwetting. The hidden patterns are prepared via a combination of wet chemical etching and two-step UV-induced thiol-ene click chemistry to graft low-surface-tension thiols and high-surface-tension thiols, respectively, on the textile surface. The as-prepared flexible textiles possess the nonwetting and wetting properties of the high-surface-tension liquids, such as water and glycerol, and the low-surface-tension liquids, such as decane and ethanol, respectively. Furthermore, the selective wetting behavior can be revealed only if the surface tension of the liquids is within a narrow range of approximately 44.8 mN m -1 to 28.1 mN m -1 , such as N,N-dimethylformamide and acetonitrile. In addition, the as-patterned textiles demonstrated high mechanical and chemical stability with long-term and repeated usage, which implies their high potential to act as novel encoded information carrier materials for flexible and textile-based devices.

  20. Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension

    NARCIS (Netherlands)

    Papazova, Diana A.; Friederich-Persson, Malou; Joles, Jaap A.|info:eu-repo/dai/nl/070114595; Verhaar, Marianne C.|info:eu-repo/dai/nl/182921840

    2015-01-01

    Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (PO2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney

  1. Effect of Kayak Ergometer Elastic Tension on Upper Limb EMG Activity and 3D Kinematics.

    Science.gov (United States)

    Fleming, Neil; Donne, Bernard; Fletcher, David

    2012-01-01

    Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil forces. Key pointsKayak ergometer elastic tension significantly alters Anterior Deltoid recruitment patterns.Kayakers maintain optimal arm kinematics despite changing external forces via altered shoulder muscle recruitment.Overhead arm movements account for a high proportion of the kayak stroke cycle.

  2. Balance Theory Revisited: Relationship Issue Relevance Affects Imbalance-Induced Tension in Workplace Relationships.

    Science.gov (United States)

    Reid, Chelsea A; Davis, Jody L; Pollack, Jeffrey M; Coughlan, Richard S

    2017-10-06

    The present work applies and extends balance theory by examining the role of relevance of issue to the relationship in balance theory processes within the context of workplace relationships. In Experiment 1, a sample of working adults (N = 81) reported greater job tension when self-supervisor dissimilarity involved a relationship-relevant (vs. non-relationship) ethical dilemma. In Experiment 2, a sample of working students (N = 185) who perceived greater self-supervisor dissimilarity about workplace (vs. family) ethics reported greater job tension, and in turn, less job satisfaction and organizational commitment. Perceiving dissimilarity with a work supervisor in attitudes about relationship-relevant issues may negatively affect outcomes at work. Importantly, these experiments demonstrated that not all dissimilarity is likely to yield negative outcomes; only relationship-relevant (vs. non-relevant) dissimilarity was a catalyst for imbalance-induced tension.

  3. The effect of rigid taping with tension on mechanical displacement of the skin and change in pain perception.

    Science.gov (United States)

    Chen, Shu-Mei; Lo, Sing Kai; Cook, Jill

    2017-07-14

    To investigate the effect of rigid taping that induces mechanical displacement of the skin on pain perception. Single group experiment design with repeated measures. Twenty-three active healthy volunteers (12 men and 11 women) participated in the study. All participants received three different taping procedures: no tape, taping with tension, and taping without tension. The order of three taping conditions was randomised. Skin displacement was measured during taping with tension. A pressure algometer was used to measure the level of pain perception once before taping, and again after each taping condition, in one testing session. The participants were blind to the values of their pressure pain threshold (PPT) during the experimental period. The mean±SD skin displacement in the condition of taping with tension was 2.58±0.49cm. There were significant differences in PPT between taping with tension and taping without tension (mean difference (mean diff)±standard error (SE) 36.43±4.22kPa, p=0.000) and no tape (mean diff±SE 44.31±3.13kPa, p=0.000). No significant difference in PPT between no tape and taping without tension was found (mean diff±SE 7.88±2.83kPa, p=0.067). Taping with tension increases the threshold of pressure pain perception. Therefore, stretch and compression caused by rigid taping with tension could disturb the nociceptive signal transmission and alter pain perception. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  4. Effects of Thermal Tension Transients on the Muscle Crossbridge

    Science.gov (United States)

    Greene, Peter R.

    2016-09-01

    The transverse thermal fluctuations of the myosin molecule are significant. This paper explores the contribution of lateral myosin bending to the developed crossbridge force and power stroke. The equipartition theorem is used to calculate the mode amplitudes for myosin bending. Crossbridge axial force Fx and power stroke Δx are developed by transverse in-plane fluctuations along the y- and z-axes. Practical applications include the effects of temperature on the flexibility of the myosin molecule stiffness and tension, relevant to man-made fabrication of synthetic muscle using micromachines and nanowires. Scaling laws for the S2 bending amplitude depend on filament length, mode number, and stiffness, as n-2,L2, and (EI)-1. This paper quantifies the effects of thermal motion on the mechanics of miniature molecular motors, including the muscle crossbridge.

  5. Gyrotropic elastic response of skyrmion crystals to current-induced tensions

    Science.gov (United States)

    Ochoa, Hector; Kim, Se Kwon; Tchernyshyov, Oleg; Tserkovnyak, Yaroslav

    2017-07-01

    We theoretically study the dynamics of skyrmion crystals in electrically insulating chiral magnets subjected to current-induced spin torques by adjacent metallic layers. We develop an elasticity theory that accounts for the gyrotropic force engendered by the nontrivial topology of the spin texture, tensions at the boundaries due to the exchange of linear and spin angular momentum with the metallic reservoirs, and dissipation in the bulk of the film. A steady translation of the skyrmion crystal is triggered by the current-induced tensions and subsequently sustained by dissipative forces, generating an electromotive force on itinerant spins in the metals. This phenomenon should be revealed as a negative drag in an open two-terminal geometry, or equivalently, as a positive magnetoresistance when the terminals are connected in parallel. We propose nonlocal transport measurements with these salient features as a tool to characterize the phase diagram of insulating chiral magnets.

  6. The Role of Osmotically-induced Tension in Binding of N-BAR to Lipid Vesicles

    Science.gov (United States)

    Dinsmore, Anthony D.; Hutchison, Jaime B.; Wood, Derek A.; Weis, Robert M.

    2014-03-01

    We measured the binding affinity of a curvature-sensing protein domain (N-BAR) as a function of applied membrane tension while the membrane curvature was held nearly constant. We focus on the N-BAR domain of Drosophila amphiphysin, which participates in a range of key cell functions including synaptic vesicle endocytosis. We monitored N-BAR binding on unilamellar vesicles composed of 90 mol% DOPC and 10 mol% PIP. Controlled tension was applied by osmotic stress. We found that the bound fraction of N-BAR was enhanced by a factor 6.5 when the tension increased from zero to 2.6 mN/m. This tension-induced response can be explained by the hydrophobic insertion mechanism with a hydrophobic domain area that is consistent with known structure. These results suggest that membrane strain might explain the previously reported curvature affinity of N-BAR. This work was supported by the National Science Foundation through grant DMR-0907195.

  7. The Cartesian Diver, Surface Tension and the Cheerios Effect

    Science.gov (United States)

    Chen, Chi-Tung; Lee, Wen-Tang; Kao, Sung-Kai

    2014-01-01

    A Cartesian diver can be used to measure the surface tension of a liquid to a certain extent. The surface tension measurement is related to the two critical pressures at which the diver is about to sink and about to emerge. After sinking because of increasing pressure, the diver is repulsed to the centre of the vessel. After the pressure is…

  8. Influência da frequência estimulatória envolvida nos efeitos analgésicos induzidos por eletroacupuntura em cervicalgia tensional Influence of the stimulating frequency involved in analgesic effects induced by electroacupuncture for neck pain due to muscular tension

    Directory of Open Access Journals (Sweden)

    P Nohama

    2009-04-01

    Full Text Available OBJETIVO: Avaliar a influência da frequência estimulatória envolvida na analgesia induzida por eletroacupuntura em cervicalgia. MÉTODOS: Comparou-se o desempenho da analgesia produzida em 2Hz, 100Hz, 1000Hz, 2500Hz e um grupo só com acupuntura, sem estímulo elétrico, avaliado por meio de algometria de pressão, Escala Visual Analógica (EVA e frequência cardíaca. Utilizou-se um estimulador elétrico microprocessado, com forma de pulso em padrão pulsado, monofásico, retangular, balanceado assimétrico, com fase secundária em exponencial decrescente, com período de estimulação de 4 segundos e repouso de 3 segundos. A amostra contou com 66 voluntários com cervicalgia tensional, idade média de 33,67±9,97 anos, 89,5% do gênero feminino e 10,5% do masculino. RESULTADOS: Não houve diferenças entre os grupos para as variáveis nota atribuída à dor pela EVA e frequência cardíaca, sendo que em todos os grupos houve melhoras analgésicas. No entanto, quando comparado o comportamento antes-depois, por meio da algometria de pressão, para um mesmo indivíduo, dentro de seu próprio grupo, houve vantagens analgésicas para o uso de 2500Hz (p=0,006 para a base da região occiptal; p=0,003 para o trapézio direito; e p=0,013 para o trapézio esquerdo, seguido de 100Hz (p=0,035, p=0,016 e p=0,038, para as mesmas regiões, respectivamente. CONCLUSÃO: Recomenda-se preferencialmente a aplicação de 2500Hz e 100Hz em eletroacupuntura para analgesia em cervicalgia tensional.OBJECTIVE: To assess the influence of the stimulating frequency involved in analgesia induced by electroacupuncture for neck pain. METHODS: The performance of the analgesia produced by 2Hz, 100Hz, 1000Hz and 2500Hz was compared with a group with acupuncture alone (without electrical stimulation, by means of pressure algometry, a visual analog scale (VAS and heart rate. We used an electrical stimulator with a microprocessor yielding standard, single-phase, rectangular and

  9. Heterogeneous structure and surface tension effects on mechanical response in pulmonary acinus: A finite element analysis.

    Science.gov (United States)

    Koshiyama, Kenichiro; Nishimoto, Keisuke; Ii, Satoshi; Sera, Toshihiro; Wada, Shigeo

    2018-01-20

    The pulmonary acinus is a dead-end microstructure that consists of ducts and alveoli. High-resolution micro-CT imaging has recently provided detailed anatomical information of a complete in vivo acinus, but relating its mechanical response with its detailed acinar structure remains challenging. This study aimed to investigate the mechanical response of acinar tissue in a whole acinus for static inflation using computational approaches. We performed finite element analysis of a whole acinus for static inflation. The acinar structure model was generated based on micro-CT images of an intact acinus. A continuum mechanics model of the lung parenchyma was used for acinar tissue material model, and surface tension effects were explicitly included. An anisotropic mechanical field analysis based on a stretch tensor was combined with a curvature-based local structure analysis. The airspace of the acinus exhibited nonspherical deformation as a result of the anisotropic deformation of acinar tissue. A strain hotspot occurred at the ridge-shaped region caused by a rod-like deformation of acinar tissue on the ridge. The local structure becomes bowl-shaped for inflation and, without surface tension effects, the surface of the bowl-shaped region primarily experiences isotropic deformation. Surface tension effects suppressed the increase in airspace volume and inner surface area, while facilitating anisotropic deformation on the alveolar surface. In the lungs, the heterogeneous acinar structure and surface tension induce anisotropic deformation at the acinar and alveolar scales. Further research is needed on structural variation of acini, inter-acini connectivity, or dynamic behavior to understand multiscale lung mechanics. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Particle-induced indentation of the alveolar epithelium caused by surface tension forces

    Science.gov (United States)

    Kojic, M.; Tsuda, A.

    2010-01-01

    Physical contact between an inhaled particle and alveolar epithelium at the moment of particle deposition must have substantial effects on subsequent cellular functions of neighboring cells, such as alveolar type-I, type-II pneumocytes, alveolar macrophage, as well as afferent sensory nerve cells, extending their dendrites toward the alveolar septal surface. The forces driving this physical insult are born at the surface of the alveolar air-liquid layer. The role of alveolar surfactant submerging a hydrophilic particle has been suggested by Gehr and Schürch's group (e.g., Respir Physiol 80: 17–32, 1990). In this paper, we extended their studies by developing a further comprehensive and mechanistic analysis. The analysis reveals that the mechanics operating in the particle-tissue interaction phenomena can be explained on the basis of a balance between surface tension force and tissue resistance force; the former tend to move a particle toward alveolar epithelial cell surface, the latter to resist the cell deformation. As a result, the submerged particle deforms the tissue and makes a noticeable indentation, which creates unphysiological stress and strain fields in tissue around the particle. This particle-induced microdeformation could likely trigger adverse mechanotransduction and mechanosensing pathways, as well as potentially enhancing particle uptake by the cells. PMID:20634359

  11. Diet-induced weight loss decreases adipose tissue oxygen tension with parallel changes in adipose tissue phenotype and insulin sensitivity in overweight humans

    NARCIS (Netherlands)

    Vink, R.G.; Roumans, N.J.; Čajlaković, M.; Cleutjens, J.P.M.; Boekschoten, M.V.; Fazelzadeh, P.; Vogel, M.A.A.; Blaak, E.E.; Mariman, E.C.; Baak, van M.A.; Goossens, G.H.

    2017-01-01

    Background/objectives: Although adipose tissue (AT) hypoxia is present in rodent models of obesity, evidence for this in humans is limited. Here, we investigated the effects of diet-induced weight loss (WL) on abdominal subcutaneous AT oxygen tension (pO 2), AT blood flow (ATBF), AT capillary

  12. Genotype tunes pancreatic ductal adenocarcinoma tissue tension to induce matricellular fibrosis and tumor progression

    DEFF Research Database (Denmark)

    Laklai, Hanane; Miroshnikova, Yekaterina A.; Pickup, Michael W.

    2016-01-01

    by increasing matricellular fibrosis and tissue tension. In contrast, epithelial STAT3 ablation attenuated tumor progression by reducing the stromal stiffening and epithelial contractility induced by loss of TGF-β signaling. In PDAC patient biopsies, higher matricellular protein and activated STAT3 were......Fibrosis compromises pancreatic ductal carcinoma (PDAC) treatment and contributes to patient mortality, yet antistromal therapies are controversial. We found that human PDACs with impaired epithelial transforming growth factor-β (TGF-β) signaling have high epithelial STAT3 activity and develop...... stiff, matricellular-enriched fibrosis associated with high epithelial tension and shorter patient survival. In several KRAS-driven mouse models, both the loss of TGF-β signaling and elevated β1-integrin mechanosignaling engaged a positive feedback loop whereby STAT3 signaling promotes tumor progression...

  13. Effects of interplay of nanoparticles, surfactants and base fluid on the interfacial tension of nanocolloids

    CERN Document Server

    Harikrishnan, A R; Agnihotri, PK; Gedupudi, Sateesh; Das, Sarit K

    2016-01-01

    A systematically designed study has been conducted to understand and clearly demarcate the degree of contribution by the constituting elements to the surface tension of nanocolloids. The effects of elements such as surfactants, particles and the combined effects of these on the interfacial tension of these complex fluids are studied employing pendant drop shape analysis method by fitting Young Laplace equation. Only particle has shown considerable increase in surface tension with particle concentration in a polar medium like DI water whereas only marginal effect particles on surface tension in weakly polar mediums like glycerol and ethylene glycol. Such behaviour has been attributed to the enhanced desorption of particles to the interface and a mathematical framework has been derived to quantify this. Combined particle and surfactant effect on surface tension of complex nanofluid system showed a decreasing behaviour with respect to the particle and surfactant concentration with a considerably feeble effect of...

  14. Finite-Size and Solvent Dependent Line Tension Effects for Nanoparticles at the Air-Liquid Surface.

    Science.gov (United States)

    Matsubara, Hiroki; Otsuka, Jo; Law, Bruce M

    2018-01-09

    The line tension for a nanoparticle (NP) at the air-liquid surface can be determined by examining the variation in NP solution surface tension with bulk NP concentration. In this publication the variation in line tension with liquid solvent is examined for the homologous series of liquids from n-decane through to n-octadecane. Finite-size line tension effects are also studied by examining the variation in line tension with NP size for NPs at the air-octadecane surface. Both the line tension variation with solvent and NP size can be qualitatively explained using an interface displacement model for the line tension.

  15. The Effects of Orchestration on Musicians' and Nonmusicians' Perception of Musical Tension

    Science.gov (United States)

    Silvey, Brian A.

    2011-01-01

    The purpose of this study was to examine the effects of orchestration on musicians' and nonmusicians' (N = 40) perception of musical tension. Participants were asked to register their perceptions of tension using the Continuous Response Digital Interface dial while listening to three orchestrations (full orchestra, brass quintet, and solo piano)…

  16. Effect of surfactant headgroups on the oil/water interface: An interfacial tension measurement and simulation study

    Science.gov (United States)

    Xu, Jiafang; Zhang, Yang; Chen, Haixiang; Wang, Pan; Xie, Zhenhua; Yao, Yongji; Yan, Youguo; Zhang, Jun

    2013-11-01

    In the article, four anionic surfactants with different headgroups and same alkyl tail, sodium dodecyl sulfonate (SDSn), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium dodecyl-di(oxyethylene) ether sulfate (AES), are adopted to investigate the influence of headgroup structure on oil-water interfacial tensions. The measured experimental results present that the capability of the four surfactants reducing interfacial tension follows the order of AES > SDBS > SDS > SDSn. Furthermore, molecular dynamic simulation (MD) is conducted to investigate the interfacial property of the four surfactants, and three parameters, interface formation energy, interfacial thickness, interaction between surfactant and water, are proposed to reveal the effecting mechanism of molecular structure on interfacial tension. And then, the polarity is studied by quantum mechanics calculation (QM) to investigate the interaction between headgroup and water molecule. The researched results indicate the addition of oxygen, benzene ring and oxyethyl group would enhance the polarity of surfactant, which induce the increase of interaction between headgroup and water molecule. The inferred interfacial tensions from MD and QM follow the order of AES > SDBS > SDS > SDSn, which is according with the experimental results. The researches explore the correlation between interfacial tensions and different headgroup structures, and these results maybe have some references for designing of high-efficient surfactant.

  17. Nandrolone decanoate reduces changes induced by hindlimb suspension in voltage-dependent tension of rat soleus muscle.

    Science.gov (United States)

    Bouhlel, Aicha; Joumaa, Wissam H; Léoty, Claude

    2003-04-01

    The effect of 8 weeks of nandrolone decanoate treatment (15 mg kg(-1)/week, 5 weeks under normal conditions followed by 3 weeks of unloading) was tested for the voltage-dependence of activation and steady-state inactivation of contraction in isolated small bundles (2-4 cells) of intact slow-twitch skeletal muscle in rats. Twenty-four male rats were divided into three groups (8 rats/group, weight matched) for 8 weeks: (1) control, (2) unloaded, and (3) unloaded-treated. Compared with age-matched control values (unloaded vs. control), suspension induced a shift in the isometric tension characteristics toward fast-twitch types in the soleus muscle. In contrast, nandrolone decanoate treatment of suspended animals reduced unweighting-induced atrophy in the muscle and maintained: (1) the relative amplitude of twitch tension to the maximal Ca(2+) activated in saponin-treated fibers (control: 3.6 +/- 0.4%, unloaded: 6.9 +/- 1.1% and unloaded-treated: 4.6 +/- 0.2%), (2) the time to peak tension (control: 130 +/- 18 ms, unloaded: 85 +/- 12 ms and unloaded-treated: 110 +/- 11 ms), (3) the time constant of relaxation (control: 320 +/- 12 ms, unloaded: 120 +/- 13 ms and unloaded-treated: 349 +/- 20 ms), (4) the relative amplitude of K(+) contracture tension to the maximal Ca(2+) activated in saponin-treated fibers (control: 82.9 +/- 3.1%, unloaded: 65.1 +/- 2.8%, and unloaded-treated: 91.7 +/- 1.9%), (5) the potential at 50% of the activation curve (control: -40.4 +/- 1.2 mV, unloaded: -35.5 +/- 1.6 mV, and unloaded-treated: -48.4 +/- 1.2 mV), and (6) the potential at 50% of the inactivation curve (control: 42.2 +/- 1.9 mV, unloaded: -34.5 +/- 1.1 mV, and unloaded-treated: -37.9 +/- 1.1 mV). This study clearly shows that treatment with anabolic-androgenic steroids can prevent atrophy and functional changes induced by 3 weeks of unweighting in rat skeletal muscles.

  18. Effects of interplay of nanoparticles, surfactants and base fluid on the surface tension of nanocolloids.

    Science.gov (United States)

    Harikrishnan, A R; Dhar, Purbarun; Agnihotri, Prabhat K; Gedupudi, Sateesh; Das, Sarit K

    2017-05-01

    A systematically designed study has been conducted to understand and demarcate the degree of contribution by the constituting elements to the surface tension of nanocolloids. The effects of elements such as surfactants, particles and the combined effects of these on the surface tension of these complex fluids are studied employing the pendant drop shape analysis method by fitting the Young-Laplace equation. Only the particle has shown an increase in the surface tension with particle concentration in a polar medium like DI water, whereas only a marginal effect of particles on surface tension in weakly polar mediums like glycerol and ethylene glycol has been demonstrated. Such behaviour has been attributed to the enhanced desorption of particles to the interface and a theory has been presented to quantify this. The combined particle and surfactant effect on the surface tension of a complex nanofluid system showed a decreasing behaviour with respect to the particle and surfactant concentration with a considerably feeble effect of particle concentration. This combined colloidal system recorded a surface tension value below the surface tension of an aqueous surfactant system at the same concentration, which is a counterintuitive observation as only the particle results in an increase in the surface tension and only the surfactant results in a decrease in the surface tension. The possible physical mechanism behind such an anomaly happening at the complex fluid air interface has been explained. Detailed analyses based on thermodynamic, mechanical and chemical equilibrium of the constituents and their adsorption-desorption characteristics as extracted from the Gibbs adsorption analysis have been provided. The present paper conclusively explains several physical phenomena observed, yet hitherto unexplained, in the case of the surface tension of such complex fluids by segregating the individual contributions of each component of the colloidal system.

  19. Effects of rhythmical muscle tension at 0.1Hz on cardiovascular resonance and the baroreflex.

    Science.gov (United States)

    Lehrer, Paul; Vaschillo, Evgeny; Trost, Zina; France, Christopher R

    2009-04-01

    This paper reports analysis of data from a previous study examining cardiovascular effects of rhythmical skeletal muscle tension (RSMT) at 0.1Hz. Our analysis examined whether 0.1Hz RSMT stimulates resonance properties of the cardiovascular system provided by baroreflex (BR) activity. Thirty-seven study participants tensed their large skeletal muscles, with and without crossing their legs, for 3-min periods at a rate of six tension/relaxation cycles/min. Tensing periods were preceded and followed by 3-min rest periods. RSMT elicited high-amplitude 0.1Hz oscillations in the cardiovascular system. We found increases in spectral power of ECG R-R interbeat interval (RRI), systolic blood pressure (SBP) and pulse transit time (PTT) at this frequency. The increases in SBP and PTT oscillations were greater than those in RRI. Only in SBP and PTT did total variability (standard deviation) increase. The phase angle between RRI and SBP oscillations was approximately 45 degrees . Although alpha low-frequency baroreflex gain was attenuated by RSMT, it was not significantly changed at 0.1Hz, consistent with BR-induced resonance effects. Our results are consistent with previous observations that 0.1Hz RSMT is effective in treating vasovagal reactions and indicate that the pathway is through resonance characteristics of the BR system. Implications for resonance applications for resonance in the sympathetically mediated vascular tone baroreflex closed loop are discussed.

  20. Effects of post mortem temperature on rigor tension, shortening and ...

    African Journals Online (AJOL)

    Fully developed rigor mortis in muscle is characterised by maximum loss of extensibility. The course of post mortem changes in ostrich muscle was studied by following isometric tension, shortening and change in pH during the first 24 h post mortem within muscle strips from the muscularis gastrocnemius, pars interna at ...

  1. Elucidation of the effects of cementite morphology on damage formation during monotonic and cyclic tension in binary low carbon steels using in situ characterization

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Motomichi, E-mail: koyama@mech.kyushu-u.ac.jp [Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395 (Japan); Yu, Yachen; Zhou, Jia-Xi [Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395 (Japan); Yoshimura, Nobuyuki [Nippon Steel & Sumitomo Metal Corporation, 20-1 Shintomi, Futtsu, Chiba 293-8511 (Japan); Sakurada, Eisaku [Nippon Steel & Sumitomo Metal Corporation, 5-3 Tokai, Aichi 476-8686 (Japan); Ushioda, Kohsaku [Nippon Steel & Sumitomo Metal Corporation, 20-1 Shintomi, Futtsu, Chiba 293-8511 (Japan); Noguchi, Hiroshi [Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395 (Japan)

    2016-06-14

    The effects of the morphology and distribution of cementite on damage formation were studied using in situ scanning electron microscopy under monotonic and cyclic tension. To investigate the effects of the morphology/distribution of cementite, intergranular cementite precipitation (ICP) and transgranular cementite precipitation (TCP) steels were prepared from an ingot of Fe-0.017 wt% C binary alloy using different heat treatments. In all cases, the damage incidents were observed primarily at the grain boundaries. The damage morphology was dependent on the cementite morphology and loading condition. Monotonic tension in the ICP steel caused cracks across the cementite plates, located at the grain boundaries. In contrast, fatigue loading in the ICP steel induced cracking at the ferrite/cementite interface. Moreover, in the TCP steel, monotonic tension- and cyclic tension-induced intergranular cracking was distinctly observed, due to the slip localization associated with a limited availability of free slip paths. When a notch is introduced to the ICP steel specimen, the morphology of the cyclic tension-induced damage at the notch tip changed to resemble that across the intergranular cementite, and was rather similar to the monotonic tension-induced damage. The damage at the notch tip coalesced with the main crack, accelerating the growth of the fatigue crack.

  2. Surface tension effects on vertical upward annular flows in a small diameter pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sadatomi, Michio, E-mail: sadatomi@mech.kumamoto-u.ac.jp [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Kawahara, Akimaro [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Suzuki, Aruta [Plant Design & Engineering Dept., Environment, Energy & Plant Headquarters, Hitachi Zosen Corporation, 7-89, Nankokita 1-chome, Suminoe-ku, Osaka, 559-8559 (Japan)

    2016-12-15

    Highlights: • Surface tension effects were clarified on annular flow in a small diameter pipe. • The mean liquid film thickness became thinner with decreasing of surface tension. • The liquid droplet fraction and the interfacial shear stress became higher with it. • New prediction methods for the above parameters were developed and validated. - Abstract: Experiments were conducted to study the surface tension effects on vertical upward annular flows in a 5 mm I.D. pipe using water and low surface tension water with a little surfactant as the test liquid and air as the test gas. Firstly, the experimental results on the mean liquid film thickness, the liquid droplet fraction and the interfacial shear stress in annular flows together with some flow pictures are presented to clarify the surface tension effects. From these, the followings are clarified: In the low surface tension case, the liquid film surface becomes rough, the liquid film thickness thin, the liquid droplet fraction high, and the interfacial shear stress high. Secondary, correlations in literatures for the respective parameters are tested against the present data. The test results show that no correlation for the respective parameters could predict well the present data. Thus, correlations are revised by accounting for the surface tension effects. The results of the experiments, the correlations tests and their revisions mentioned above are presented in the present paper.

  3. Muscle tension induced after learning enhances long-term narrative and visual memory in healthy older adults.

    Science.gov (United States)

    Nielson, Kristy A; Wulff, Laura L; Arentsen, Timothy J

    2014-03-01

    Arousing events are better remembered than mundane events. Indeed, manipulation of arousal, such as by muscle tension, can influence memory even when it occurs shortly after learning. Indeed, our founding study showed this approach can raise delayed memory performance in older adults to a level comparable to that of unaided young adults. Yet, systematic studies, especially those investigating different modalities or types of memory, have not been done. This study investigated the effects of a brief bout of isometric exercise via handgrip on narrative and visuospatial episodic memory in healthy elders. Forty-seven participants completed the Logical Memory subtest of the Wechsler Memory Scales III (LM) and the Benton Visual Retention Test (BVRT), followed alternately by no treatment and by moderately squeezing a sand-filled latex ball for 1-min (counterbalanced order and test forms). Isometric exercise significantly increased both positive and negative affect ratings. Retention was tested 2 weeks later. Delayed recall and recognition of LM was enhanced by arousal relative to control, as was recognition of the BVRT. The results extend past findings that muscle tension induced after learning modulates memory consolidation, extending findings in elders to suggest that a simple form of isometric exercise can have practical effects, such as aiding memory for stories and images. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Nuclear and hadron matter equation of state within the induced surface tension approach

    Science.gov (United States)

    Sagun, V. V.; Bugaev, K. A.; Ivanytskyi, A. I.; Oliinychenko, D. R.; Mishustin, I. N.

    2017-12-01

    We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard core repulsion. The suggested equation of state explicitly contains the surface tension which is induced by particle interaction. At high densities such a surface tension vanishes and in this way it switches the excluded volume treatment of hard core repulsion to its eigen volume treatment. The great advantage of the developed model is that the number of equations to be solved is two and it does not depend on the number of independent hard-core radii. Using the suggested equation of state we obtained a high quality fit of the hadron multiplicities measured at AGS, SPS, RHIC and ALICE energies and studied the properties of the nuclear matter phase diagram. It is shown the developed equation of state is softer than the gas of hard spheres and remains causal up to the several normal nuclear densities. Therefore, it could be applied to the neutron star interior modeling.

  5. Interference fit effect on holed single plates loaded with tension-tension stresses

    Directory of Open Access Journals (Sweden)

    D. Croccolo

    2012-07-01

    Full Text Available This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (1075MPa of Ultimate strength and 990MPa of Yield strength with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: free hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N curves pointed out an increased fatigue life of the interference fit specimens compared with the free hole ones. The numerical investigation was performed in order to analyse the stress fields by applying an elastic plastic 2D simulation with a commercial Finite Element software. The stress history and distribution along the contact interference of the fitted samples indicates a significant reduction of the local stress range due to the externally applied loading (remote stress since a residual and compressive stress field is generated by the pin insertion.

  6. Physicians' perspectives of managing tensions around dimensions of effective communication in the emergency department.

    Science.gov (United States)

    Dean, Marleah; Oetzel, John G

    2014-01-01

    The purpose of this study was to explore emergency department (ED) physicians' perspectives of guidelines for effective communication. More specifically, the ways in which physicians manage the tensions among effective communication dimensions framed by relational dialectics theory are examined. This study used in-depth interviews with 17 ED physicians and 70 hours of observations to identify five dimensions of effective communication: efficiency, clarity/accuracy, relevance, comprehension, and rapport. Two communication tensions resulted from these dimensions: efficiency versus rapport and efficiency versus comprehension. In almost all instances, physicians chose efficient communication at the expense of comprehension or rapport. In addition, there was a tension between patient and physician perspectives of clarity and relevance that physicians tended to resolve by emphasizing what was relevant and clear from their own perspective. Implications for managing tensions in terms of efficiency and a physician-centered approach are discussed.

  7. Effect of epidural blockade and oxygen therapy on changes in subcutaneous oxygen tension after abdominal surgery

    DEFF Research Database (Denmark)

    Rosenberg, J; Pedersen, U; Erichsen, C J

    1994-01-01

    The effect of oxygen therapy (37% by face mask) and epidural local anesthetic blockade (9 ml 0.5% bupivacaine at Th9-11 level) on wound oxygenation was evaluated in eight otherwise healthy patients undergoing elective colorectal resection. The patients were monitored continuously for subcutaneous...... any of the measured values. Oxygen therapy before epidural blockade increased median subcutaneous oxygen tension from 60 to 71 mmHg (P oxygen tension with oxygen therapy was 30 (15-55) min...... without epidural blockade and 15 (10-20) min with blockade (P oxygen tension with or without oxygen therapy after elective uncomplicated major abdominal surgery....

  8. Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips

    KAUST Repository

    Li, Huawei

    2013-04-01

    This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.

  9. Interfacial Tension Effect on Cell Partition in Aqueous Two-Phase Systems.

    Science.gov (United States)

    Atefi, Ehsan; Joshi, Ramila; Mann, Jay Adin; Tavana, Hossein

    2015-09-30

    Aqueous two-phase systems (ATPS) provide a mild environment for the partition and separation of cells. We report a combined experimental and theoretical study on the effect of interfacial tension of polymeric ATPS on the partitioning of cells between two phases and their interface. Two-phase systems are generated using polyethylene glycol and dextran of specific properties as phase-forming polymers and culture media as the solvent component. Ultralow interfacial tensions of the solutions are precisely measured using an axisymmetric drop shape analysis method. Partition experiments show that two-phase systems with an interfacial tension of 30 μJ/m(2) result in distribution of majority of cells to the bottom dextran phase. An increase in the interfacial tension results in a distribution of cells toward the interface. An independent cancer cell spheroid formation assay confirms these observations: a drop of the dextran phase containing cancer cells is dispensed into the immersion polyethylene glycol phase to form a cell-containing drop. Only at very small interfacial tensions do cells remain within the drop to aggregate into a spheroid. We perform a thermodynamic modeling of cell partition to determine variations of free energy associated with displacement of cells in ATPS with respect to the ultralow interfacial tensions. This modeling corroborates with the experimental results and demonstrates that at the smallest interfacial tension of 30 μJ/m(2), the free energy is a minimum with cells in the bottom phase. Increasing the interfacial tension shifts the minimum energy and partition of cells toward the interfacial region of the two aqueous phases. Examining differences in the partition behavior and minimum free energy modeling of A431.H9 cancer cells and mouse embryonic stem cells shows that the surface properties of cells further modulate partition in ATPS. This combined approach provides a fundamental understanding of interfacial tension role on cell partition in

  10. Fluctuation-induced forces between rings threaded around a polymer chain under tension

    CERN Document Server

    Gilles, F M; Pastorino, C

    2016-01-01

    We characterize the fluctuation properties of a polymer chain under external tension and the fluctuation-induced forces between two ring molecules threaded around the chain. The problem is relevant in the context of fluctuation-induced forces in soft matter systems, features of liquid interfaces and to describe properties of polyrotaxanes and slide-ring materials. We perform molecular dynamics simulations of the Kremer-Grest bead-spring model for the polymer and a simple ring-molecule model, in the canonical ensemble. We study transverse fluctuations of the stretched chain, as a function of chain stretching and in the presence of ring-shaped threaded molecules. The fluctuation spectra of the chains are analyzed in equilibrium at constant temperature and the differences in presence of two ring molecules are compared. For the rings located at fixed distances, we find an attractive fluctuation-induced force between the rings, proportional to the temperature and decaying with the ring distance. We characterize th...

  11. Surface tension of polymer melts - experimental investigations of its effect on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    The surface tension of polymer melts is important for the bond strength of two component polymer parts through their roles in the process of wetting, adsorption and adhesion. This investigation deals with the influence of the melt surface tension and substrate surface energy on the polymer......-polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEl, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies....... The results and discussion presented in this paper reflect the temperature dependent behaviours of the surface tension and surface energy of polymers and their effects on the polymer-polymer bond strength....

  12. Surface tension of polymer melts - experimental investigations of its effects on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Jankova Atanasova, Katja; Hansen, Hans Nørgaard

    The surface tension of polymer melts is important for the bond strength of two component polymer parts through their roles in the process of wetting, adsorption and adhesion. This investigation deals with the influence of the melt surface tension and substrate surface energy on the polymer......-polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEI, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies....... The results and discussion presented in this paper reflect the temperature dependent behaviours of the surface tension and surface energy of polymers and their effects on the polymer-polymer bond strength....

  13. Effects of Singing Bowl Sound Meditation on Mood, Tension, and Well-being: An Observational Study.

    Science.gov (United States)

    Goldsby, Tamara L; Goldsby, Michael E; McWalters, Mary; Mills, Paul J

    2016-09-30

    Poor mood and elevated anxiety are linked to increased incidence of disease. This study examined the effects of sound meditation, specifically Tibetan singing bowl meditation, on mood, anxiety, pain, and spiritual well-being. Sixty-two women and men (mean age 49.7 years) participated. As compared with pre-meditation, following the sound meditation participants reported significantly less tension, anger, fatigue, and depressed mood (all Ps meditation experienced a significantly greater reduction in tension compared with participants experienced in this meditation (P meditation may be a feasible low-cost low technology intervention for reducing feelings of tension, anxiety, and depression, and increasing spiritual well-being. This meditation type may be especially useful in decreasing tension in individuals who have not previously practiced this form of meditation. © The Author(s) 2016.

  14. The effect of tension wood on roughness of poplar wood and its modification by steaming

    Directory of Open Access Journals (Sweden)

    اصغر طارمیان

    2016-12-01

    Full Text Available In this research, the effect of tension wood on the roughness of poplar wood in tangential and radial sections was investigated. Steaming at120 ̊C for 30 and 60 min was aslo applied to reduce the roughness. The potential use of roughness measurement technique for macroscopically detection of tension wood was one of the main objectives of this research. Before roughness measurement and for accurate sampling, the detection of tension wood was carried out using Herzberg reagent and microscopic studies. The roughness of samples was measured by stylus profilometer at 12 % moisture content and the surface quality was also studied by stereo-microscope. Results showed that there is no significant difference in the radial and tangential roughness between tension and normal wood. No difference was also observed between the roughness of tangential and radial sections of both types of woods. In contrast, stereo-microscopic studies clearly showed the higher roughness of tension wood. Steaming for 30 min increased the roughness but the treatment for 60 min had a decreasing effect on the roughness of both types of woods. Overall, it can be concluded that the roughness measurement technique cannot be used as a suitable method to nondestructively detect the poplar tension wood.

  15. Effect of Ageing on the Passive and Active Tension and Pharmacodynamic Characteristics of Rat Coronary Arteries

    DEFF Research Database (Denmark)

    Sheykhzade, Majid; Simonsen, Anja Hviid; Boonen, Harrie C.M.

    2012-01-01

    The influence of ageing on the passive and active tension and pharmacodynamic characteristics of intramural coronary arteries from 3-month-old and 2-year-old male Wistar rats was investigated using an isometric myograph. The passive vessel wall tension measured in Ca2+-free physiological salt...... solution at L0 was significantly greater in arteries from old rats (1.46 ± 0.10 Nm–1, n = 7) than in young rats (1.13 ± 0.13 Nm–1, n = 6). However, the maximal active tension at L0 was similar. The spontaneous myogenic tone was increased by age and the vasorelaxation induced by extracellular K...... from both young and old rats. The slopes of the regression lines of the Schild plots were not significantly different from unity and the estimated pKB values for ketanserin were similar. In conclusion, ageing is associated with changes in passive mechanical characteristics as well as changes...

  16. Numerical Study on the Effects of Gravity and Surface Tension on Condensation Process in Square Minichannel

    Science.gov (United States)

    Li, Panpan; Chen, Zhenqian; Shi, Juan

    2017-12-01

    A volume of fluid (VOF) method is adopted to simulate the condensation of R134a in a horizontal single square minichannel with 1 mm side length. The effect of gravity, surface tension and gas-liquid interfacial shear stress are taken into account. The result denotes that condensation is first appeared at the corner of channel, and then the condensation is stretched at the effect of surface tension until the whole channel boundary covered. The effect of gravity on the distribution of the liquid film depends on the channel length. In short channel, the gravity shows no significant effect, the distribution shape of steam in the cross section of the channel is approximately circular. In long channel, due to the influence of gravity, the liquid converges at the bottom under the effect of gravity, and the thickness of the liquid film at the bottom is obviously higher than that of the upper part of the channel. The effect of surface tension on condensation is also analysed. The surface tension can enhance the condensation heat transfer significantly when the inlet mass flux is low. Whilst, at high mass flux, the enhancement of surface tension on heat transfer is unobvious and can be neglected.

  17. The effect of temperature and pH variations on the surface tension of EDTA solutions.

    Science.gov (United States)

    Yılmaz, Zeliha; Aktemur, Sevinc; Buzoglu, Hatice Dogan; Gümüsderelioglu, Menemse

    2011-06-01

    Surface tension of a liquid is one of the major factors that affect the wetting of a solid. The reduction in surface tension could improve the contact of irrigants with the dentinal walls of the root canal system. This in vitro study was conducted to evaluate the effect of pH and temperature variations on the surface tension of EDTA solutions. Three solutions, 17% EDTA, REDTA, and EDTA-T, were prepared and adjusted to have a pH of 5.5, 7.5, and 10.5. The surface tension of the test solutions was measured at 22 °C by the pendant drop technique, and the measurement was repeated after heating the solution at 37 °C. Differences among the experimental groups were statistically analyzed using three-way analysis of variance followed by the Bonferroni test for pair-wise comparison. The results of this study showed that there were significant differences in the surface tension values of solutions depending on the pH and temperature (P surface tension level of the EDTA solution dramatically decreased when surfactant was added to the EDTA solution in both pH and temperature variations (P surface tension value at a pH of 5.5 of all EDTA solutions, at a pH of 7.5 of EDTA and REDTA solutions, and at a pH of 10.5 of only REDTA solution (P surface tension of EDTA with and without surfactant is influenced by pH and temperature. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  18. Effects of small surface tension in Hele-Shaw multifinger dynamics: an analytical and numerical study.

    Science.gov (United States)

    Pauné, E; Siegel, M; Casademunt, J

    2002-10-01

    We study the singular effects of vanishingly small surface tension on the dynamics of finger competition in the Saffman-Taylor problem, using the asymptotic techniques described by Tanveer [Philos. Trans. R. Soc. London, Ser. A 343, 155 (1993)] and Siegel and Tanveer [Phys. Rev. Lett. 76, 419 (1996)], as well as direct numerical computation, following the numerical scheme of Hou, Lowengrub, and Shelley [J. Comput. Phys. 114, 312 (1994)]. We demonstrate the dramatic effects of small surface tension on the late time evolution of two-finger configurations with respect to exact (nonsingular) zero-surface-tension solutions. The effect is present even when the relevant zero-surface-tension solution has asymptotic behavior consistent with selection theory. Such singular effects, therefore, cannot be traced back to steady state selection theory, and imply a drastic global change in the structure of phase-space flow. They can be interpreted in the framework of a recently introduced dynamical solvability scenario according to which surface tension unfolds the structurally unstable flow, restoring the hyperbolicity of multifinger fixed points.

  19. Effects of different femoral tunnel positions on tension changes in anterolateral ligament reconstruction.

    Science.gov (United States)

    Katakura, Mai; Koga, Hideyuki; Nakamura, Kaori; Sekiya, Ichiro; Muneta, Takeshi

    2017-04-01

    Several kinds of anterolateral ligament (ALL) reconstructions to augment intra-articular anterior cruciate ligament reconstruction to better control anterolateral rotational instability (ALRI) have been reported. However, the optimal femoral attachment site for ALL reconstruction is still unclear. The purpose of this study was to investigate the effects of different femoral attachment sites on the tension changes through knee motions in different situations in order to determine a recommended femoral attachment site for ALL reconstruction. Six fresh-frozen cadaveric knees were included. ALL reconstructions were performed with three different femoral attachment sites (F1: 2 mm anterior and 2 mm distal to the lateral epicondyle, F2: 4 mm posterior and 8 mm proximal to the lateral epicondyle and F3: position for the lateral extra-articular tenodesis). The graft tension changes were measured by a graft tensioning system during knee flexion-extension and manual maximum internal/external tibial rotation in the following situations: (1) intact, (2) ALL cut, (3) ALL and ACL cut and (4) ALL cut and ACL reconstructed. Effects of the different femoral attachment sites, the route superficial or deep to the LCL, and the situations of (1) to (4) were calculated via repeated-measures analysis of variance. The tension of F1 was higher in flexion and lower in extension, whereas the tension of F2 and F3 was higher in extension and lower in flexion. F2 showed the smallest tension change. Situations of (1) to (4) did not affect tension changes. The graft tension became higher with internal rotation and lower with external rotation regardless of femoral attachment sites or situations. With F2-4 mm posterior and 8 mm proximal to the lateral epicondyle-the reconstructed ALL had the least tension change with only a slight increase in tension as the knee extended. This result indicates that F2 is recommended for ALL reconstruction to better control ALRI, which will help determine the

  20. Investigations of surface-tension effects due to small-scale complex boundaries

    Science.gov (United States)

    Feng, Jiansheng

    these two different types of surfaces differed by about 50° ˜ 60°, with the low-adhesion surfaces at about 120° ˜ 130° and the high-adhesion surfaces at about 70° ˜ 80°. Characterizations of both the microscopic structures and macroscopic wetting properties of these product surfaces allowed us to pinpoint the structural features responsible for specific wetting properties. It is found that the advancing contact angle was mainly determined by the primary structures while the receding contact angle is largely affected by the side-wall slope of the secondary features. This study established a platform for further exploration of the structure aspects of surface wettability. In the third and final project (Chapter 4), we demonstrated a new type of microfluidic channel that enable asymmetric wicking of wetting fluids based on structure-induced direction-dependent surface-tension effect. By decorating the side-walls of open microfluidic channels with tilted fins, we were able to experimentally demonstrate preferential wicking behaviors of various IPA-water mixtures with a range of contact angles in these channels. A simplified 2D model was established to explain the wicking asymmetry, and a complete 3D model was developed to provide more accurate quantitative predictions. The design principles developed in this study provide an additional scheme for controlling the spreading of fluids. The research presented in this dissertation spreads out across a wide range of physical phenomena (wicking, wetting, and capillarity), and involves a number of computational and experimental techniques, yet all of these projects are intrinsically united under a common theme: we want to better understand how simple fluids respond to small-scale complex surface structures as manifestations of surface-tension effects. We hope our findings can serve as building blocks for a larger scale endeavor of scientific research and engineering development. After all, the pursue of knowledge is most

  1. COMPUTER SIMULATIONS OF SPRAY RETENTION BY A 3D BARLEY PLANT: EFFECT OF FORMULATION SURFACE TENSION.

    Science.gov (United States)

    Massinon, M; De Cock, N; Salah, S Ouled Taleb; Lebeau, F

    2015-01-01

    A spray retention model was used in this study to explore theoretically the effect of a range of mixture surface tension on the spray retention and the variability of deposits. The spray retention model was based on an algorithm that tested whether droplets from a virtual nozzle intercepted a 3D plant model. If so, the algorithm determined the contribution of the droplet to the overall retention depending on the droplet impact behaviour on the leaf; adhesion, rebound or splashing. The impact outcome probabilities, function of droplet impact energy, were measured using high-speed imaging on an excised indoor grown barley leaf (BBCH12) both for pure water (surface tension of 0.072 N/m) and a non-ionic super spreader (static surface tension of 0.021 N/m) depending on the surface orientation. The modification of spray mixture properties in the simulations was performed by gradually changing the spray the droplet impact probabilities between pure water and a solution with non-ionic surfactant exhibiting super spreading properties. The plant architecture was measured using a structured light scanner. The final retention was expressed as the volume of liquid retained by the whole plant relative to the projected leaf surface area in the main spray direction. One hundred simulations were performed at different volumes per hectare and flat-fan nozzles for each formulation surface tension. The coefficient of variation was used as indicator of variability of deposits. The model was able to discriminate between mixture surface tension. The spray retention increased as the mixture surface tension decreased. The variability of deposits also decreased as the surface tension decreased. The proposed modelling approach provides a suited tool for sensitivity analysis: nozzle kind, pressure, volume per hectare applied, spray mixture physicochemical properties, plant species, growth stage could be screened to determine the best spraying characteristics maximizing the retention. The

  2. Effect of an alcohol-based caries detector on the surface tension of sodium hypochlorite preparations.

    Science.gov (United States)

    Rossi-Fedele, Giampiero; Guastalli, Andrea R

    2015-01-01

    The purpose of this study was to evaluate the effect of an alcohol-based caries detector (Kurakay) on the surface tension of a conventional sodium hypochlorite (NaOCl) preparation, and a product containing a surface-active agent (Chlor-XTRA). The surface tensions of the following solutions were tested: NaOCl, a mixture of NaOCl and Kurakay 9:1 w/w, Chlor-XTRA, a mixture of Chlor-XTRA and Kurakay 9:1 w/w. Ten measurements per test solution were made at 20°C, using an optical method called the "Pendant drop method", with a commercially available apparatus. The addition of Kurakay reduced the surface tension for NaOCl (p0.05). Statistically significant differences between the NaOCl and Chlor-XTRA groups were found (psurface tension values for NaOCl only. Taking into account the fact that mixtures of NaOCl and Kurakay have been used to assess the penetration of root canal irrigants in vitro, the related changes in surface tension are a possible source of bias.

  3. Oscillating drop/bubble tensiometry: effect of viscous forces on the measurement of interfacial tension.

    Science.gov (United States)

    Freer, E M; Wong, H; Radke, C J

    2005-02-01

    The oscillating drop/bubble technique is increasingly popular for measuring the interfacial dilatational properties of surfactant/polymer-laden fluid/fluid interfaces. A caveat of this technique, however, is that viscous forces are important at higher oscillation frequencies or fluid viscosities; these can affect determination of the interfacial tension. Here, we experimentally quantify the effect of viscous forces on the interfacial-tension measurement by oscillating 100 and 200 cSt poly(dimethylsiloxane) (PDMS) droplets in water at small amplitudes and frequencies ranging between 0.01 and 1 Hz. Due to viscous forces, the measured interfacial tension oscillates sinusoidally with the same frequency as the oscillation of the drop volume. The tension oscillation precedes that of the drop volume, and the amplitude varies linearly with Capillary number, Ca=DeltamuomegaDeltaV/gammaa(2), where Deltamu=mu(D)-mu is the difference between the bulk Newtonian viscosities of the drop and surrounding continuous fluid, omega is the oscillation frequency of the drop, DeltaV is the amplitude of volume oscillation, gamma is the equilibrium interfacial tension between the PDMS drop and water, and a is the radius of the capillary. A simplified model of a freely suspended spherical oscillating-drop well explains these observations. Viscous forces distort the drop shape at Ca>0.002, although this criterion is apparatus dependent.

  4. Boerhaave's syndrome and tension pneumothorax secondary to Norovirus induced forceful emesis

    DEFF Research Database (Denmark)

    Venø, Søren; Eckardt, Jens

    2013-01-01

    Boerhaave's syndrome or spontaneous esophageal perforation is a rare condition, with high mortality. We describe a case of Boerhaave's syndrome presenting with tension pneumothorax. The patient was infected with Norovirus and developed Boerhaave's syndrome, initially thought to be gastroenteritis...

  5. Effect of concentration and temperature on surface tension of sodium hyaluronate saline solutions.

    Science.gov (United States)

    Ribeiro, Walkiria; Mata, José Luis; Saramago, Benilde

    2007-06-19

    The effect of concentration and temperature on the surface tension of sodium hyaluronate (NaHA) saline solutions was investigated using the technique of the shape of pendant drops. The decay rate of the surface tension with the increase of NaHA concentration was well-described by the empirical Hua-Rosen equation. Adsorption at the air-liquid interface was estimated using the Gibbs equation. The temperature dependence of a dilute solution and a semidilute entangled solution was numerically fitted with a second-order polynomial equation. The surface behavior of the NaHA saline solutions was interpreted in terms of their known viscoelastic properties.

  6. THE EFFECTS OF VARIED TENSIONS OF KINESIOLOGY TAPING ON QUADRICEPS STRENGTH AND LOWER LIMB FUNCTION.

    Science.gov (United States)

    de Jesus, Julio Fernandes; Franco, Yuri Rafael Dos Santos; Nannini, Stella Bispo; Nakaoka, Gustavo Bezerra; Dos Reis, Amir Curcio; Bryk, Flavio Fernandes

    2017-02-01

    Kinesiology Taping (KT) may promote changes in muscle strength and motor performance, topics of great interest in the sports-medicine sciences. These characteristics are purported to be associated with the tension generated by the KT on the skin. However, the most suitable tension for the attainment of these strength and performance effects has not yet been confirmed. The purpose of the present study was to analyze the effects of different tensions of KT on the isometric contraction of the quadriceps and lower limb function of healthy individuals over a period of seven days. Blind, randomized, clinical trial. One hundred and thirty healthy individuals were distributed into the following five groups: control (without KT); KT0 (KT without tension); KT50; KT75 and KT100 (approximately 50%, 75% and 100% tension applied to the tape, respectively). Assessments of isometric quadriceps strength were conducted using a hand held dynamometer. Lower limb function was assessed through Single Hop Test for Distance, with five measurement periods: baseline; immediately after KT application; three days after KT; five days after KT; and 72h after KT removal (follow-up). There were no statistically significant differences ( p  > 0.05) at any of the studied periods on participants' quadriceps strength nor in the function of the lower dominant limb, based on comparisons between the control group and the experimental groups. KT applied with different tensions did not produce modulations, in short or long-term, on quadriceps' strength or lower limb function of healthy individuals. Therefore, this type of KT application, when seeking these objectives, should be reconsidered. 1b.

  7. THE EFFECTS OF VARIED TENSIONS OF KINESIOLOGY TAPING ON QUADRICEPS STRENGTH AND LOWER LIMB FUNCTION

    Science.gov (United States)

    Franco, Yuri Rafael dos Santos; Nannini, Stella Bispo; Nakaoka, Gustavo Bezerra; dos Reis, Amir Curcio; Bryk, Flavio Fernandes

    2017-01-01

    Background Kinesiology Taping (KT) may promote changes in muscle strength and motor performance, topics of great interest in the sports-medicine sciences. These characteristics are purported to be associated with the tension generated by the KT on the skin. However, the most suitable tension for the attainment of these strength and performance effects has not yet been confirmed. Hypothesis/Purpose The purpose of the present study was to analyze the effects of different tensions of KT on the isometric contraction of the quadriceps and lower limb function of healthy individuals over a period of seven days. Study Design Blind, randomized, clinical trial. Methods One hundred and thirty healthy individuals were distributed into the following five groups: control (without KT); KT0 (KT without tension); KT50; KT75 and KT100 (approximately 50%, 75% and 100% tension applied to the tape, respectively). Assessments of isometric quadriceps strength were conducted using a hand held dynamometer. Lower limb function was assessed through Single Hop Test for Distance, with five measurement periods: baseline; immediately after KT application; three days after KT; five days after KT; and 72h after KT removal (follow-up). Results There were no statistically significant differences (p > 0.05) at any of the studied periods on participants’ quadriceps strength nor in the function of the lower dominant limb, based on comparisons between the control group and the experimental groups. Conclusion KT applied with different tensions did not produce modulations, in short or long-term, on quadriceps’ strength or lower limb function of healthy individuals. Therefore, this type of KT application, when seeking these objectives, should be reconsidered. Level of Evidence 1b PMID:28217419

  8. Effect of radioprotective sulphydryl compounds on the oxygen tension in the spleen of mice

    NARCIS (Netherlands)

    Meer, C. van der; Valkenburg, P.W.; Remmelts, M.

    1961-01-01

    In a previous paper the mechanism of the radioprotective action of the biologically active amines histamine, epinephrine, tryptamine and β-phenylethylamine was investigated. In studying the effect of these compounds on the oxygen tension in the spleen and bone marrow of unanæsthetized mice strong

  9. Effect of chromatographic separation on ASP system interface tension and the countermeasures

    Directory of Open Access Journals (Sweden)

    Jiawei REN

    2016-06-01

    Full Text Available Because of the existing chromatographic separation phenomenon, ASP flooding changes original nature of the system. Therefore, in laboratory ultra-low interfacial tension ASP system is preferred for sand packs flow experiment to research on the effect of chromatographic separation on ASP system interface tension. The two parameters of "breakthrough time" and "output difference" are used to describe the degree of chromatographic separation, and the produced fluid interfacial tensions at the outlet end at 120 min is measured. The research shows that there exists chromatographic separation between three chemicals of ASP system, with first polymer breakthrough and finally surfactant breakthrough; there is most serious chromatographic separation between surfactant and polymer, while minimum chromatographic separation between alkali and polymer; chromatographic separation makes ASP interfacial tension increase from 10-3 magnitude to 10-2 magnitude, affecting flooding effect of ASP system. Thus, reducing the loss of surfactant in the formation will be the main measure to reduce the degree of chromatographic separation. Using sophorolipid as sacrificial agent to replace part of the surfactant injected into formation before ASP system can effectively reduce the impact of chromatography separation and more effectively improve the ultimate recovery ratio.

  10. The effect of post-tensioning force magnitude and eccentricity on the natural bending frequency of cracked post-tensioned concrete beams

    Science.gov (United States)

    Noble, D.; Nogal, M.; O'Connor, A. J.; Pakrashi, V.

    2015-07-01

    The effect of prestress force magnitude on the dynamic properties of uncracked prestressed concrete structures is something that has been widely debated among researchers to date. The effect of pre- and post-tensioning force magnitude on the natural bending frequencies of cracked prestressed concrete structures is something that is more established, and widely agreed upon. This paper describes the results of dynamic impact testing on damaged post- tensioned concrete beams. The natural bending frequency of the cracked beams were determined through experimental modal analysis. Dynamic impact response signals were obtained at different levels of post-tensioning force for the cracked beams. The Fast Fourier Transform was implemented and a peak picking algorithm was subsequently used to determine the natural bending frequencies of the beams. The relationship between prestressing force and natural frequency for both the cracked and uncracked beam sections was determined. The results for the cracked beams were compared to the results for the same uncracked beam sections. A marked difference in vibration behaviour was observed for the cracked beams between the nonfully prestressed and the fully prestressed case. Conclusions from the study are drawn and have profound implications in the fields of system identification and structural health monitoring in pre- and post-tensioned concrete structures.

  11. Size Effect Of Glulam Beams In Tension Perpendicular To Grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Odin Clorius, Christian; Damkilde, Lars

    2007-01-01

    The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents the hypothesis that...

  12. Measurement of effective alveolar carbon dioxide tension during spontaneous breathing in normal subjects and patients with chronic airways obstruction.

    OpenAIRE

    Jordanoglou, J.; Koulouris, N; Kyroussis, D.; Rapakoulias, P.; Vassalos, P.; Madianos, J.

    1995-01-01

    BACKGROUND--The measurement of effective alveolar carbon dioxide tension (PA-CO2eff) is still a matter of debate. It has, however, become common practice to use arterial instead of alveolar CO2 tension for computing alveolar oxygen tension (PAO2) and physiological dead space, not only in normal subjects but also in patients. The purpose of this study was to estimate alveolar CO2 tension during spontaneous breathing with a new bedside technique which is simple and non-invasive, and to compare ...

  13. The Effect of String Tension Variation on the Perceived Pitch of a Classical Guitar

    Directory of Open Access Journals (Sweden)

    Wanda Jadwiga Lewis

    2014-09-01

    Full Text Available Actual motion of a vibrating guitar string is a superposition of many possible shapes (modes in which it could vibrate. Each of these modes has a corresponding frequency, and the lowest frequency is associated with a shape idealised as a single wave, referred to as the fundamental mode. The other contributing modes, each with their own progressively higher frequency, are referred to as overtones, or harmonics. By attaching a string to a medium (a soundboard capable of a response to the vibrating string, sound waves are generated. The sound heard is dominated by the fundamental mode, ‘coloured’ by contributions from the overtones, as explained by the classical theory of vibration. The classical theory, however, assumes that the string tension remains constant during vibration, and this cannot be strictly true; when considering just the fundamental mode, string tension will reach two maximum changes, as it oscillates up and down. These changes, occurring twice during the fundamental period match the frequency of the octave higher, 1st overtone. It is therefore plausible to think that the changing tension effect, through increased force on the bridge and, therefore, greater soundboard deflection, could be amplifying the colouring effect of (at least the 1st overtone.In this paper, we examine the possible influence of string tension variation on tonal response of a classical guitar. We use a perturbation model based on the classical result for a string in general vibration in conjunction with a novel method of assessment of plucking force that incorporates the engineering concept of geometric stiffness, to assess the magnitude of the normal force exerted by the string on the bridge. The results of our model show that the effect of tension variation is significantly smaller than that due to the installed initial static tension, and affects predominantly the force contribution arising from the fundamental mode. We, therefore, conclude that string

  14. Fluctuation-induced forces between inclusions in a fluid membrane under tension.

    Science.gov (United States)

    Lin, Hsiang-Ku; Zandi, Roya; Mohideen, Umar; Pryadko, Leonid P

    2011-11-25

    We develop an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each object's shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension.

  15. Size effect of glulam beams in tension perpendicular to grain

    DEFF Research Database (Denmark)

    Astrup, Thomas; Clorius, Christian Odin; Damkilde, Lars

    2007-01-01

    The strength of wood is reduced when the stressed volume is increased. The phenomenon is termed size effect and is often explained as being stochastic in the sense that the probability of weak locations occurring in the wood increases with increased volume. This paper presents the hypothesis...... that the lower strength is caused by stress concentrations. The stress concentrations arise from the anisotropic structure of wood, and are therefore deterministic. The hypothesis is substantiated through extensive FEM-calculations and experiments. A reasonable agreement between ultimate stresses determined...

  16. Effect of tension lap splice on the behavior of high strength concrete (HSC beams

    Directory of Open Access Journals (Sweden)

    Ahmed El-Azab

    2014-12-01

    Full Text Available In the recent years, many research efforts have been carried out on the bond strength between normal strength concrete (NSC and reinforcing bars spliced in tension zones in beams. Many codes gave a minimum splice length for tension and compression reinforcement as a factor of the bar diameter depending on many parameters such as concrete strength, steel yield stress, shape of bar end, shape of bar surface and also bar location. Also, codes gave another restriction about the percentage of total reinforcement to be spliced at the same time. Comparatively limited attention has been directed toward the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. HSC has high modulus of elasticity, high density and long-term durability. This research presents an experimental study on the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. It reports the influence of several parameters on bond in splices. The parameters covered are casting position, splice length as a factor of bar diameter, bar diameter and reinforcement ratio. The research involved tests on sixteen simply-supported beams of 1800 mm span, 200 mm width and 400 mm thickness made of HSC. In each beam, the total tensile steel bars were spliced in the constant moment zone. Crack pattern, crack propagation, cracking load, failure load and mi span deflection were recorded and analyzed to study the mentioned parameters effect.

  17. Surface tension prevails over solute effect in organic-influenced cloud droplet activation.

    Science.gov (United States)

    Ovadnevaite, Jurgita; Zuend, Andreas; Laaksonen, Ari; Sanchez, Kevin J; Roberts, Greg; Ceburnis, Darius; Decesari, Stefano; Rinaldi, Matteo; Hodas, Natasha; Facchini, Maria Cristina; Seinfeld, John H; O' Dowd, Colin

    2017-06-29

    The spontaneous growth of cloud condensation nuclei (CCN) into cloud droplets under supersaturated water vapour conditions is described by classic Köhler theory. This spontaneous activation of CCN depends on the interplay between the Raoult effect, whereby activation potential increases with decreasing water activity or increasing solute concentration, and the Kelvin effect, whereby activation potential decreases with decreasing droplet size or increases with decreasing surface tension, which is sensitive to surfactants. Surface tension lowering caused by organic surfactants, which diminishes the Kelvin effect, is expected to be negated by a concomitant reduction in the Raoult effect, driven by the displacement of surfactant molecules from the droplet bulk to the droplet-vapour interface. Here we present observational and theoretical evidence illustrating that, in ambient air, surface tension lowering can prevail over the reduction in the Raoult effect, leading to substantial increases in cloud droplet concentrations. We suggest that consideration of liquid-liquid phase separation, leading to complete or partial engulfing of a hygroscopic particle core by a hydrophobic organic-rich phase, can explain the lack of concomitant reduction of the Raoult effect, while maintaining substantial lowering of surface tension, even for partial surface coverage. Apart from the importance of particle size and composition in droplet activation, we show by observation and modelling that incorporation of phase-separation effects into activation thermodynamics can lead to a CCN number concentration that is up to ten times what is predicted by climate models, changing the properties of clouds. An adequate representation of the CCN activation process is essential to the prediction of clouds in climate models, and given the effect of clouds on the Earth's energy balance, improved prediction of aerosol-cloud-climate interactions is likely to result in improved assessments of future

  18. A Simple Size Effect Model for Tension Perpendicular to the Grain

    DEFF Research Database (Denmark)

    Pedersen, M. U.; Clorius, Christian Odin; Damkilde, Lars

    2003-01-01

    The strength in tension perpendicular to the grain is known to decrease with an increase in the stressed volume. Usually this size effect is explained on a stochastic basis, that is, an explanation relying on the increased probability of encountering a strength reducing flaw when the volume of th...... on a deterministic basis. Arguments for such a simple deterministic explanation of size effect is found in finite element modelling, using the orthotropic stiffness characteristics in the transverse plane of wood....

  19. The effect of differing ambient oxygen tensions on wound infection.

    Science.gov (United States)

    Hunt, T K; Linsey, M; Grislis, H; Sonne, M; Jawetz, E

    1975-01-01

    Wound infections were studied in rabbits using two standard inocula (approximately equal to 10-4 and approximately equal to 10-6) of Pseudomonas aeruginosa injected into subcutaneous wound dead space made by implantation of standard wire mesh cylinders. The inoculation was done on the fourth day after implantation of the cylinders in animals kept from the day of implantation in atmospheres of 12%, 21%, or 45% oxygen content. Samples of wound fluid (0.2 ml) were removed for quantitative culture just before inoculation and 3, 7, 14, and 21 days later. No positive cultures resulted from samples taken before inoculation. One uninoculated wound served as a control in each animal. None of these control wounds became infected. Culture counts were significantly highest in the anoxic group and lowest in the hyperoxic group. Established infections were significantly lowest in the hyperoxics and highest in the hypoxics. The percent of wounds showing a significant culture count showed a similar trend. The mechanisms of this effect is not known, but a possible mechanism lies in the relative inability of leucocytes to kill this bacterium under hypoxic conditions.

  20. The dependence of surface tension on surface properties of ionic surfactant solution and the effects of counter-ions therein.

    Science.gov (United States)

    Wang, Chuangye; Morgner, Harald

    2014-11-14

    In the present paper, we aim to investigate the dependence of surface tension on the surface properties and reveal the counter-ion effects on the adsorption of ionic surfactants on the solution surface. The surface tension, surface excess and surface concentration (defined as the amount of surfactant adsorbed in the surface phase divided by the surface area) of two anionic surfactants, namely dodecyl sulfate sodium and dodecyl sulfate caesium, dissolved in non-aqueous polar solvent formamide have been separately measured at 6 °C through independent experiments. Then, the correlation of surface tension with surface concentration and that of surface tension with surface excess is inspected in detail. It was found that there is a linear relationship between the surface tension and the surface concentration for the pure solutions of each surfactant, but their surface tension and surface excess cannot be correlated linearly. It is striking that the same surface tension-surface concentration linearity holds for two different surfactants, although they have apparently distinct counter-ions. Based on this finding, it is derived that the surface tension is decided by surface concentration of the surface active ions. After analyzing the surface structure, it is concluded that the counter-ions affect the surface tension indirectly through modifying the adsorption amount of the surface active ions in the surface layer.

  1. Political Skill as Neutralizer of Felt Accountability-Job Tension Effects on Job Performance Ratings: A Longitudinal Investigation

    Science.gov (United States)

    Hochwarter, Wayne A.; Ferris, Gerald R.; Gavin, Mark B.; Perrewe, Pamela L.; Hall, Angela T.; Frink, Dwight D.

    2007-01-01

    This study examined the effects of felt accountability, political skill, and job tension on job performance ratings. Specifically, we hypothesized that felt accountability would lead to higher (lower) job performance ratings when coupled with high (low) levels of political skill, and that these relationships would be mediated by job tension. Data…

  2. Effect of temperature and concentration on the surface tension of chia seed mucilage

    Science.gov (United States)

    Fu, Yuting; Arye, Gilboa

    2017-04-01

    The production of mucilage by the seed coat during hydration is a common adaptation of many different plant species. The mucilage may play many ecological roles in adaptation and seed germination in diverse environments, especially in extreme desert conditions. The major compound of the seed mucilage is polysaccharides (e.g. pectins and hemicelluloses), which makes it highly hydrophilic. Consequently, it can hydrate quickly in the presence of water; forming a gel like coating surrounding the seed. However, the seed mucilage also reported to contain small amounts of protein and lipid which may exhibit surface activity at the water-air interface. As a result, decay in the surface tension of water can be occur and consequently a reduction in soil capillary pressure. This in turn may affect the water retention and transport during seed germination. The physical properties of the seeds mucilage have been studied mainly in conjunction with its rheological properties. To the best of our knowledge, its surface activity at the water-air interface has been reported mainly in the realms of food engineering, using a robust method of extraction. The main objective of this study was to quantify the effect of temperature and concentration on the surface tension of seed mucilage. The mucilage in this study was extracted from chia (Salvia hispanica L.) seeds, using distilled water (1:20 w/w) by shaking for 12 h at 4°C. The extracts were freeze dried after centrifuge (5000rpm for 20min). Fresh samples of different concentrations, ranging from 0.5 to 6 mg/ml, were prepared before each surface tension measurements. The equilibrium surface tension was measured by the Wilhelmy plate method using a tensiometer (DCAT 11, Data Physics) with temperature control unit. For a given mucilage concentration, surface tension measurements carried out at 5, 15, 25, 35, 45 °C. The quantitative and thermodynamic analysis of the results will be presented and discussed.

  3. Effects of the transcutaneous electrode temperature on the accuracy of transcutaneous carbon dioxide tension

    DEFF Research Database (Denmark)

    Sørensen, Line C; Brage-Andersen, Lene; Greisen, Gorm

    2011-01-01

    The harmful effect of hypocapnia on the neonatal brain emphasizes the importance of monitoring arterial carbon dioxide tension (PaCO2). Transcutaneous monitoring of carbon dioxide (tcPCO2) reduces the need for arterial blood sampling. Drawbacks are high electrode temperature causing risks of skin...... burning. The aim was to determine the accuracy and precision of tcPCO2 at reduced electrode temperature....

  4. EFFECT OF KAYAK ERGOMETER ELASTIC TENSION ON UPPER LIMB EMG ACTIVITY AND 3D KINEMATICS

    OpenAIRE

    Neil Fleming; Bernard Donne; David Fletcher

    2012-01-01

    Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-e...

  5. Tensile transmission across the lumbar fasciae in unembalmed cadavers: effects of tension to various muscular attachments.

    Science.gov (United States)

    Barker, Priscilla J; Briggs, Christopher A; Bogeski, Goce

    2004-01-15

    Traction was applied to muscles attaching to the posterior and middle layers of lumbar fascia (PLF, MLF). Effects on fasciae were determined via tensile force measures and movement of markers. To document tensile transmission to the PLF and MLF when traction was applied to latissimus dorsi (LD), gluteus maximus (GM), external and internal oblique (EO, IO), and transversus abdominis (TrA) in unembalmed cadavers. A previous study on embalmed cadavers applied traction to muscle attachments while monitoring fascial movement but did not test TrA or the MLF. The PLF and MLF were dissected then marked on eight unembalmed cadavers. A strain gauge was inserted through fascia at L3; 10N traction was applied to each muscle attachment while photographs and tension measures were taken. Movement of fascial markers was detected photographically. Fascial widths were also measured. Tension was clearly transmitted to fascial vertebral attachments. Tensile forces and fascial areas affected were highest for traction on LD and TrA in the PLF and for TrA in the MLF. Movement of PLF markers from tension on LD and TrA occurred bilaterally between T12 and S1. Effects from other muscles were variably bilateral, with those from GM and IO occurring below L3 and those from EO occurring above L3. Tensile forces were relatively high in the MLF and its width was less than half that of the PLF. Low levels of tension are effectively transmitted between TrA and the MLF or PLF. Via them, TrA may influence intersegmental movement.

  6. Flow-induced elongation of von Willebrand factor precedes tension-dependent activation.

    Science.gov (United States)

    Fu, Hongxia; Jiang, Yan; Yang, Darren; Scheiflinger, Friedrich; Wong, Wesley P; Springer, Timothy A

    2017-08-23

    Von Willebrand factor, an ultralarge concatemeric blood protein, must bind to platelet GPIbα during bleeding to mediate hemostasis, but not in the normal circulation to avoid thrombosis. Von Willebrand factor is proposed to be mechanically activated by flow, but the mechanism remains unclear. Using microfluidics with single-molecule imaging, we simultaneously monitored reversible Von Willebrand factor extension and binding to GPIbα under flow. We show that Von Willebrand factor is activated through a two-step conformational transition: first, elongation from compact to linear form, and subsequently, a tension-dependent local transition to a state with high affinity for GPIbα. High-affinity sites develop only in upstream regions of VWF where tension exceeds ~21 pN and depend upon electrostatic interactions. Re-compaction of Von Willebrand factor is accelerated by intramolecular interactions and increases GPIbα dissociation rate. This mechanism enables VWF to be locally activated by hydrodynamic force in hemorrhage and rapidly deactivated downstream, providing a paradigm for hierarchical mechano-regulation of receptor-ligand binding.Von Willebrand factor (VWF) is a blood protein involved in clotting and is proposed to be activated by flow, but the mechanism is unknown. Here the authors show that VWF is first converted from a compact to linear form by flow, and is subsequently activated to bind GPIbα in a tension-dependent manner.

  7. Tension Headache

    Science.gov (United States)

    ... your head Tenderness on your scalp, neck and shoulder muscles Tension headaches are divided into two main categories — ... that monitor and give you feedback on body functions such as muscle tension, heart rate and blood pressure. You then ...

  8. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids

    OpenAIRE

    Hu, Bin; Kieweg, Sarah L.

    2012-01-01

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading ...

  9. Effects of texture on shear band formation in plane strain tension/compression and bending

    DEFF Research Database (Denmark)

    Kuroda, M.; Tvergaard, Viggo

    2007-01-01

    model analysis. Third, shear band developments in plane strain pure bending of a sheet specimen with the typical textures are studied. Regions near the surfaces in a bent sheet specimen are approximately subjected to plane strain tension or compression. From this viewpoint, the bendability of a sheet......In this study, effects of typical texture components observed in rolled aluminum alloy sheets on shear band formation in plane strain tension/compression and bending are systematically studied. The material response is described by a generalized Taylor-type polycrystal model, in which each grain...... is characterized in terms of an elastic-viscoplastic continuum slip constitutive relation. First, a simple model analysis in which the shear band is assumed to occur in a weaker thin slice of material is performed. From this simple model analysis, two important quantities regarding shear band formation...

  10. Effect of massage therapy on pain, anxiety, relaxation, and tension after colorectal surgery: A randomized study.

    Science.gov (United States)

    Dreyer, Nikol E; Cutshall, Susanne M; Huebner, Marianne; Foss, Diane M; Lovely, Jenna K; Bauer, Brent A; Cima, Robert R

    2015-08-01

    The purpose of this randomized controlled trial was to evaluate the effect of postoperative massage in patients undergoing abdominal colorectal surgery. One hundred twenty-seven patients were randomized to receive a 20-min massage (n = 61) or social visit and relaxation session (no massage; n = 66) on postoperative days 2 and 3. Vital signs and psychological well-being (pain, tension, anxiety, satisfaction with care, relaxation) were assessed before and after each intervention. The study results indicated that postoperative massage significantly improved the patients' perception of pain, tension, and anxiety, but overall satisfaction was unchanged. In conclusion, massage may be beneficial during postoperative recovery for patients undergoing abdominal colorectal surgery. Further studies are warranted to optimize timing and duration and to determine other benefits in this clinical setting. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. MIGRAINE AND TENSION-TYPE HEADACHE IN CHILDREN: THE APPROACH TO EFFECTIVE TREATMENT. PART 2

    Directory of Open Access Journals (Sweden)

    A. V. Sergeev

    2012-01-01

    Full Text Available Pediatric neurologists often have to prescribe drugs off-label in children, according to individual approach to every patient and weighing possible benefits and risk of side-effects. Multidisciplinary approach to migraine and tension-type headache treatment in children, including correction of comorbid psychiatric and somatic disorders, is a critical point in decrease of frequency and severity of headaches and normalization of everyday children’s activity. In the second part of the article the authors discuss the problems of symptomatic (episodic drugs taking in order to arrest a headache attack and preventive (regular prolonged drug taking directed on decrease of frequency and severity of headaches medical treatment of migraine and tension-type headaches in pediatric practice.

  12. Effect of Tension and Curvature of Skin on Insertion Characteristics of Microneedle Array

    Science.gov (United States)

    Tachikawa, Hiroto; Takano, Naoki; Nishiyabu, Kazuaki; Miki, Norihisa; Ami, Yoshimichi

    Recent MEMS (micro electro mechanical system) fabrication techniques have made it possible to produce painless microneedles precisely enough to be inserted into epidermis layer penetrating the stratum corneum of human skin. This paper presents a testing procedure to evaluate the insertion characteristics of microneedle array using cultured human skin considering the tension and the curvature. First, the biaxial strain applied to the cultured human skin was measured by optical technique with image processing. It was found that almost constant strain could be successfully given within a certain area and that error factors in the experiment except the thickness variation of the cultured skin were negligible. Next, using a microneedle square array for brain machine interface (BMI) application, the effects of biaxial tension and the curvature on insertion characteristics were discussed. Within the above mentioned area with high strain, the needles were successfully inserted.

  13. Effectiveness of direct vs indirect technique myofascial release in the management of tension-type headache.

    Science.gov (United States)

    Ajimsha, M S

    2011-10-01

    Tension-type headache (TTH) is essentially defined as bilateral headache of a pressing or tightening quality without a known medical cause. Myofascial release (MFR) is currently being applied for patients with TTH but its efficacy has not been evaluated formally. To investigate whether direct technique myofascial release (DT-MFR) reduces the frequency of headache more effectively than the indirect technique myofascial release (IDT-MFR) in comparison to a Control Group receiving slow soft stroking. Randomized, controlled, single blinded trial. The clinical wing of Myofascial Therapy and Research Foundation, Kerala, India. 63 patients with episodic or chronic tension-type headache. DT-MFR, IDT-MFR or Control. The techniques were administered by certified myofascial release practitioners and consisted of 24 sessions per patient over 12 weeks. Difference in numbers of days with headache between Weeks 1-4 (i.e. 4 weeks prior to start of Intervention) and Weeks 17-20, following 12 weeks of Intervention between Weeks 5-16 as recorded by participants in headache diaries. The number of days with headache per 4 weeks decreased by 7.1 (2.6) [mean (SD)] days in the DT-MFR group compared with 6.7 (1.8) days in the IDT-MFR group and 1.6 (0.5) days in the control group, (P Myofascial Release is more effective than the Control Intervention for tension headache. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Lack of caspase-3 attenuates immobilization-induced muscle atrophy and loss of tension generation along with mitigation of apoptosis and inflammation

    Science.gov (United States)

    Zhu, Shimei; Nagashima, Michio; Khan, Mahammad A.S; Yasuhara, Shingo; Kaneki, Masao; Jeevendra Martyn, J. A.

    2012-01-01

    Introduction Immobilization by casting induces disuse muscle atrophy (DMA). Methods Using wild type (WT) and caspase-3 knockout (KO) mice, we evaluated the effect of caspase-3 on muscle mass, apoptosis and inflammation during DMA. Results Caspase-3 deficiency significantly attenuated muscle mass decrease [gastrocnemius: 28 ± 1% in KO vs. 41 ± 3% in WT; soleus: 47 ± 2% in KO vs. 56 ± 2% in WT; (P immobilized versus contralateral hindlimb. Lack of caspase-3 decreased immobilization-induced increased apoptotic myonuclei (3.2-fold) and macrophage infiltration (2.2-fold) in soleus muscle and attenuated increased monocyte chemoattractant protein-1 mRNA expression (2-fold in KO vs. 18-fold in WT) in gastrocnemius. Conclusion Caspase-3 plays a key role in DMA and associated decreased tension, presumably by acting on the apoptosis and inflammation pathways. PMID:23401051

  15. Skin tension related to tension reduction sutures.

    Science.gov (United States)

    Hwang, Kun; Kim, Han Joon; Kim, Kyung Yong; Han, Seung Ho; Hwang, Se Jin

    2015-01-01

    The aim of this study was to compare the skin tension of several fascial/subcutaneous tensile reduction sutures. Six upper limbs and 8 lower limbs of 4 fresh cadavers were used. At the deltoid area (10 cm below the palpable acromion) and lateral thigh (midpoint from the palpable greater trochanter to the lateral border of the patella), and within a 3 × 6-cm fusiform area of skin, subcutaneous tissue defects were created. At the midpoint of the defect, a no. 5 silk suture was passed through the dermis at a 5-mm margin of the defect, and the defect was approximated. The initial tension to approximate the margins was measured using a tensiometer.The tension needed to approximate skin without any tension reduction suture (S) was 6.5 ± 4.6 N (Newton). The tensions needed to approximate superficial fascia (SF) and deep fascia (DF) were 7.8 ± 3.4 N and 10.3 ± 5.1 N, respectively. The tension needed to approximate the skin after approximating the SF was 4.1 ± 3.4 N. The tension needed to approximate the skin after approximating the DF was 4.9 ± 4.0 N. The tension reduction effect of approximating the SF was 38.8 ± 16.4% (2.4 ± 1.5 N, P = 0.000 [ANOVA, Scheffé]). The tension reduction effect of approximating the DF was 25.2% ± 21.9% (1.5 ± 1.4 N, P = 0.001 [ANOVA, Scheffé]). The reason for this is thought to be that the SF is located closely to the skin unlike the DF. The results of this study might be a basis for tension reduction sutures.

  16. The effect of low-level laser irradiation on muscle tension and hardness compared among three wavelengths

    Science.gov (United States)

    Kogure, Shinichi

    2013-01-01

    Background and Aims: It has been reported that low-level laser irradiation (LLLI) can influence muscle tissue by retarding attenuation of muscle tension. Since the efficacy of LLLI on the effects of muscle contraction remains unclear, we examined in an in vivo animal model whether LLLI affects both muscle tension and muscle hardness in a wavelength-dependent manner, using the rat gastrocnemius muscle. Material and Methods: Forty Sprague-Dawley adult rats were used. Under pentobarbital sodium anesthesia, their gastrocnemius muscle and tibial nerve were exteriorized. Diode LLLI systems delivering 3 wavelengths (405, 532, and 808 nm; 100 mW output) were used. Ten sets of tetanus (tetanic contractions) were delivered to the tibial nerve followed by a brief rest or LLLI for 15 s and an additional 7 sets of tetanus with an inter-stimulus interval of 5 min. The muscle tension and muscle hardness were measured with a tension transducer and hardness meter, respectively. Results: 405 nm LLLI did not influence either muscle tension or hardness. 532 nm LLLI significantly improved the maintenance of muscle tension compared with the 808 nm group (Phardness compared with the other groups (P<0.05). Conclusion: We conclude that LLLI has wavelength-dependent effects on the gastrocnemius muscle and LLLI at appropriate wavelengths and dosimetry offers potential in the treatment to relieve muscle tension or stiffness. PMID:24204094

  17. Cation alkyl side chain length and symmetry effects on the surface tension of ionic liquids.

    Science.gov (United States)

    Almeida, Hugo F D; Freire, Mara G; Fernandes, Ana M; Lopes-da-Silva, José A; Morgado, Pedro; Shimizu, Karina; Filipe, Eduardo J M; Lopes, José N Canongia; Santos, Luís M N B F; Coutinho, João A P

    2014-06-10

    Aiming at providing a comprehensive study of the influence of the cation symmetry and alkyl side chain length on the surface tension and surface organization of ionic liquids (ILs), this work addresses the experimental measurements of the surface tension of two extended series of ILs, namely R,R'-dialkylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(n)C(n)im][NTf2]) and R-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(n)C(1)im][NTf2]), and their dependence with temperature (from 298 to 343 K). For both series of ILs the surface tension decreases with an increase in the cation side alkyl chain length up to aliphatic chains no longer than hexyl, here labeled as critical alkyl chain length (CACL). For ILs with aliphatic moieties longer than CACL the surface tension displays an almost constant value up to [C12C12im][NTf2] or [C16C1im][NTf2]. These constant values further converge to the surface tension of long chain n-alkanes, indicating that, for sufficiently long alkyl side chains, the surface ordering is strongly dominated by the aliphatic tails present in the IL. The enthalpies and entropies of surface were also derived and the critical temperatures were estimated from the experimental data. The trend of the derived thermodynamic properties highlights the effect of the structural organization of the IL at the surface with visible trend shifts occurring at a well-defined CACL in both symmetric and asymmetric series of ILs. Finally, the structure of a long-alkyl side chain IL at the vacuum-liquid interface was also explored using Molecular Dynamics simulations. In general, it was found that for the symmetric series of ILs, at the outermost polar layers, more cations point one of their aliphatic tails outward and the other inward, relative to the surface, than cations pointing both tails outward. The number of the former, while being the preferred conformation, exceeds the latter by around 75%.

  18. The effect of a nonanatomic repair of the meniscal horn attachment on meniscal tension: a biomechanical study.

    Science.gov (United States)

    Stärke, Christian; Kopf, Sebastian; Gröbel, Karl-Heinz; Becker, Roland

    2010-03-01

    The purpose of this biomechanical study was to investigate the potential effect of a nonanatomic repair of the meniscal horn attachment on the resultant circumferential tension in a large animal model and to show that the circumferential tension of the meniscus affects the local stress of the cartilage. All investigations were done in the medial compartment of porcine knees. First, the anterior horn attachment of the meniscus was mechanically separated from the surrounding tibial bone and fitted with a force transducer (n = 8). The femorotibial joint was loaded in compression at different flexion angles, and the resultant tension at the horn attachment was recorded. The measurements were done with the horn attachment at its anatomic position and repeated with the horn attachment being displaced medially or laterally by 3 mm. In the second part the local deformation of the cartilage under a femorotibial compressive load was measured at different levels of meniscal hoop tension (n = 5). A nonanatomic position of the horn attachment had a significant effect on the resultant tension (P horn attachment 3 mm medially decreased the tension at the horn attachment by 49% to 73%, depending on flexion angle and femorotibial load. The opposite placement resulted in a relative increase in the tension by 28% to 68%. Lower levels of meniscal hoop tension caused increased deformation of the cartilage (P horn attachment strongly affects conversion of femorotibial loads into circumferential tension. There is a narrow window for a functionally sufficient repair of meniscal root tears. Although clinical inferences are limited because the specimens used were from a different species, there seems to be only a narrow window for a mechanically sufficient repair of root tears. Copyright 2010 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  19. Driven polymer translocation in good and bad solvent: Effects of hydrodynamics and tension propagation.

    Science.gov (United States)

    Moisio, J E; Piili, J; Linna, R P

    2016-08-01

    We investigate the driven polymer translocation through a nanometer-scale pore in the presence and absence of hydrodynamics both in good and bad solvent. We present our results on tension propagating along the polymer segment on the cis side that is measured for the first time using our method that works also in the presence of hydrodynamics. For simulations we use stochastic rotation dynamics, also called multiparticle collision dynamics. We find that in the good solvent the tension propagates very similarly whether hydrodynamics is included or not. Only the tensed segment is by a constant factor shorter in the presence of hydrodynamics. The shorter tensed segment and the hydrodynamic interactions contribute to a smaller friction for the translocating polymer when hydrodynamics is included, which shows as smaller waiting times and a smaller exponent in the scaling of the translocation time with the polymer length. In the bad solvent hydrodynamics has a minimal effect on polymer translocation, in contrast to the good solvent, where it speeds up translocation. We find that under bad-solvent conditions tension does not spread appreciably along the polymer. Consequently, translocation time does not scale with the polymer length. By measuring the effective friction in a setup where a polymer in free solvent is pulled by a constant force at the end, we find that hydrodynamics does speed up collective polymer motion in the bad solvent even more effectively than in the good solvent. However, hydrodynamics has a negligible effect on the motion of individual monomers within the highly correlated globular conformation on the cis side and hence on the entire driven translocation under bad-solvent conditions.

  20. Surface tension effects on the phase transition of a DPPC bilayer with and without protein: a molecular dynamics simulation.

    Science.gov (United States)

    Kong, Xian; Qin, Shanshan; Lu, Diannan; Liu, Zheng

    2014-05-14

    While the surface tension of a cell membrane, or a plasma membrane, regulates cell functions, little is known about its effect on the conformational changes of the lipid bilayer and hence the resulting changes in the cell membrane. To obtain some insights into the phase transition of the lipid bilayer as a function of surface tension, we used a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayer as a model lipid bilayer and aquaporin (AqpZ), a transmembrane channel protein for water, as a model embedded protein. A coarse-grained molecular dynamics simulation was applied to illustrate the phase transition behavior of the pure DPPC bilayer and aquaporin-embedded DPPC bilayer under different surface tensions. It was shown that an increased surface tension reduced the phase transition temperature of the DPPC bilayer. As for the DPPC bilayer in gel form, no significant changes occurred in the structure of the bilayer in response to the surface tension. Once in a liquid crystal state, both the structure and properties of the DPPC bilayer, such as area per lipid, lipid order parameters, bilayer thickness and lateral diffusion coefficients, were responsive to the magnitude of surface tension in a linear way. The presence of aquaporin attenuated the compact alignment of the lipid bilayer, hindered the parallel movement, and thus made the DPPC bilayer less sensitive to the surface tension.

  1. The energy release rate of a pressurized crack in soft elastic materials: effects of surface tension and large deformation.

    Science.gov (United States)

    Liu, Tianshu; Long, Rong; Hui, Chung-Yuen

    2014-10-21

    In this paper we present a theoretical study on how surface tension affects fracture of soft solids. In classical fracture theory, the resistance to fracture is partly attributed to the energy required to create new surfaces. Thus, the energy released to the crack tip must overcome the surface energy in order to propagate a crack. In soft materials, however, surface tension can cause significant deformation and can reduce the energy release rate for crack propagation by resisting the stretch of crack surfaces. We quantify this effect by studying the inflation of a penny-shaped crack in an infinite elastic body with applied pressure. To avoid numerical difficulty caused by singular fields near the crack tip, we derived an expression for the energy release rate which depends on the applied pressure, the surface tension, the inflated crack volume and the deformed crack area. This expression is evaluated using a newly developed finite element method with surface tension elements. Our calculation shows that, when the elasto-capillary number ω ≡ σ/Ea is sufficiently large, where σ is the isotropic surface tension, E is the small strain Young's modulus and a is the initial crack radius, both the energy release rate and the crack opening displacement of an incompressible neo-Hookean solid are significantly reduced by surface tension. For a sufficiently high elasto-capillary number, the energy release rate can be negative for applied pressure less than a critical amount, suggesting that surface tension can cause crack healing in soft elastic materials.

  2. Effect of low oxygen tension on tissue-engineered cartilage construct development in the concentric cylinder bioreactor.

    Science.gov (United States)

    Saini, Sunil; Wick, Timothy M

    2004-01-01

    Cartilage is exposed to low oxygen tension in vivo, suggesting culture in a low-oxygen environment as a strategy to enhance matrix deposition in tissue-engineered cartilage in vitro. To assess the effects of oxygen tension on cartilage matrix accumulation, porous polylactic acid constructs were dynamically seeded in a concentric cylinder bioreactor with bovine chondrocytes and cultured for 3 weeks at either 20 or 5% oxygen tension. Robust chondrocyte proliferation and matrix deposition were achieved. After 22 days in culture, constructs from bioreactors operated at either 20 or 5% oxygen saturation had similar chondrocyte densities and collagen content. During the first 12 days of culture, the matrix glycosaminoglycan (GAG) deposition rate was 19.5 x 10(-9) mg/cell per day at 5% oxygen tension and 65% greater than the matrix GAG deposition rate at 20% oxygen tension. After 22 days of bioreactor culture, constructs at 5% oxygen contained 4.5 +/- 0.3 mg of GAG per construct, nearly double the 2.5 +/- 0.2 mg of GAG per construct at 20% oxygen tension. These data demonstrate that culture in bioreactors at low oxygen tension favors the production and retention of GAG within cartilage matrix without adversely affecting chondrocyte proliferation or collagen deposition. Bioreactor studies such as these can identify conditions that enhance matrix accumulation and construct development for cartilage tissue engineering.

  3. [Effect of bile acids on surface tension of bronchoalveolar lavage fluid in rabbits].

    Science.gov (United States)

    Wang, Fei; Zhao, Cong; Tian, Yinghong; Yin, Yanru

    2014-10-01

    To observe changes in surface tension of bronchoalveolar lavage fluids (BALF) in rabbits with hyperbilirubinemia and the influence of bile diluents and 5 different bile acids on BALF surface tension to provide better insight into the regulatory role of bile acids on respiratory function. Bronchoalveolar lavage with 0.9% normal saline was carried out in 30 male New Zealand rabbits and the surface tensions of BALF were measured. The changes in BALF surface tension was measured in rabbits with hyperbilirubinemia. Different concentrations of bile diluents, normal saline, or water solutions of 5 bile acids were added into the collected BALF to test their influence on the surface tension of BALF. The BALF from rabbits with hyperbilirubinemia showed a significantly increased surface tension (Psurface tension of the BALF by 21.15%, 26.09%, and 19.64%, respectively. Among the water solutions of the 5 bile acids, UDCA produced no significant influence on the surface tension of BALF while CDCA, CA, LCA, and DCA increased the surface tension by 16.10%, 21.66%, 14.21%, and 13.05%, respectively. The surface tension of BALF increases significantly during hyperbilirubinemia. Bile diluents as well as the free bile acids CDCA, CA, LCA and DCA, but not UDCA, can increase the surface tension of BALF, suggesting that these bile acids may emulsify pulmonary alveolar surfactants to increase the alveolar surface tension.

  4. Treatment of General Tension: Subjective and Physiological Effects of Progressive Relaxation.

    Science.gov (United States)

    Borkovec, T. D.; And Others

    1978-01-01

    Presence or absence of tension release significantly influenced the number of relaxation cycles necessary to produce reports of deep relaxation, frequency of practice, and successfulness of eliminating daily tension at follow-up. Subject's ability to reduce physiological activity by a procedure contributed to reductions in subjective tension.…

  5. Effectiveness of Physical Therapy in Patients with Tension-type Headache: Literature Review.

    Science.gov (United States)

    Espí-López, Gemma Victoria; Arnal-Gómez, Anna; Arbós-Berenguer, Teresa; González, Ángel Arturo López; Vicente-Herrero, Teófila

    2014-01-01

    Tension-type headache (TTH) is a disease with a great incidence on quality of life and with a significant socioeconomic impact. The aim of this review is to determine the effectiveness of physical therapy by using manual therapy (MT) for the relief of TTH. A review was done identifying randomized controlled trials through searches in MEDLINE, PEDro, Cochrane and CINAHL (January 2002 - April 2012). English-language studies, with adult patients and number of subjects not under 11, diagnosed with episodic tension-type headache (ETTH) and chronic tension-type headache (CTTH) were included. Initial search was undertaken with the words Effectiveness, Tension-type headache, and Manual therapy (39 studies). In addition, a search which included terms related to treatments such as physiotherapy, physical therapy, spinal manipulation was performed (25 studies). From the two searches 9 studies met the inclusion criteria and were analysed finding statistically significant results: 1) myofascial release, cervical traction, neck muscles trigger points in cervical thoracic muscles and stretching; 2) Superficial heat and massage, connective tissue manipulation and vertebral Cyriax mobilization; 3) cervical or thoracic spinal manipulation and cervical chin-occipital manual traction; 4) massage, progressive relaxation and gentle stretching, program of active exercises of shoulder, neck and pericranial muscles; 5) massage, passive rhythmic mobilization techniques, cervical, thoracic and lumbopelvic postural correction and cranio-cervical exercises; 6) progressive muscular relaxation combined with joint mobilization, functional, muscle energy, and strain/counterstrain techniques, and cranial osteopathic treatment; 7) massage focused on relieving myofascial trigger point activity; 8) pressure release and muscle energy in suboccipital muscles; 9) combination of mobilizations of the cervical and thoracic spine, exercises and postural correction. All studies used a combination of different

  6. Indomethacin lowers optic nerve oxygen tension and reduces the effect of carbonic anhydrase inhibition and carbon dioxide breathing

    DEFF Research Database (Denmark)

    Pedersen, D B; Eysteinsson, T; Stefánsson, E

    2004-01-01

    Prostaglandins are important in blood flow regulation. Carbon dioxide (CO(2)) breathing and carbonic anhydrase inhibition increase the oxygen tension in the retina and optic nerve. To study the mechanism of this effect and the role of cyclo-oxygenase in the regulation of optic nerve oxygen tension...... (ONPO(2)), the authors investigated how indomethacin affects ONPO(2) and the ONPO(2) increases caused by CO(2) breathing and carbonic anhydrase inhibition in the pig....

  7. Effect of oxygen tension on bioenergetics and proteostasis in young and old myoblast precursor cells

    Directory of Open Access Journals (Sweden)

    M. Konigsberg

    2013-01-01

    Full Text Available In the majority of studies using primary cultures of myoblasts, the cells are maintained at ambient oxygen tension (21% O2, despite the fact that physiological O2 at the tissue level in vivo is much lower (~1–5% O2. We hypothesized that the cellular response in presence of high oxygen concentration might be particularly important in studies comparing energetic function or oxidative stress in cells isolated from young versus old animals. To test this, we asked whether oxygen tension plays a role in mitochondrial bioenergetics (oxygen consumption, glycolysis and fatty acid oxidation or oxidative damage to proteins (protein disulfides, carbonyls and aggregates in myoblast precursor cells (MPCs isolated from young (3–4 m and old (29–30 m C57BL/6 mice. MPCs were grown under physiological (3% or ambient (21% O2 for two weeks prior to exposure to an acute oxidative insult (H2O2. Our results show significantly higher basal mitochondrial respiration in young versus old MPCs, an increase in basal respiration in young MPCs maintained at 3% O2 compared to cells maintained at 21% O2, and a shift toward glycolytic metabolism in old MPCs grown at 21% O2. H2O2 treatment significantly reduced respiration in old MPCs grown at 3% O2 but did not further repress respiration at 21% O2 in old MPCs. Oxidative damage to protein was higher in cells maintained at 21% O2 and increased in response to H2O2 in old MPCs. These data underscore the importance of understanding the effect of ambient oxygen tension in cell culture studies, in particular studies measuring oxidative damage and mitochondrial function.

  8. A theoretical study on surfactant adsorption kinetics: effect of bubble shape on dynamic surface tension.

    Science.gov (United States)

    Yang, Ming-Wei; Wei, Hsien-Hung; Lin, Shi-Yow

    2007-12-04

    A planar or spherical fluid-liquid interface was commonly assumed on studying the surfactant adsorption kinetics for a pendant bubble in surfactant solutions. However, the shape of a pendant bubble deviates from a sphere unless the bubble's capillary constant is close to zero. Up to date, the literature has no report about the shape effect on the relaxation of surface tension due to the shape difference between a pendant bubble and a sphere. The dynamic surface tension (DST), based on the actual shape of a pendant bubble with a needle, of the diffusion-controlled process is simulated using a time-dependent finite element method in this work. The shape effect and the existence of a needle on DST are investigated. This numerical simulation resolves also the time-dependent bulk surfactant concentration. The depth of solution needed to satisfy the classical Ward-Tordai infinite-solution assumption was also studied. For a diffusion-controlled adsorption process, bubble shape and needle size are two major factors affecting the DST. The existence of a needle accelerates the bulk diffusion for a small bubble; however, the shape of a large pendant bubble decelerates the bulk diffusion. An example using this method on the DST data of C12E4 is illustrated at the end of this work.

  9. Effects of BAK-free travoprost treatment for 3 years in patients with normal tension glaucoma.

    Science.gov (United States)

    Inoue, Kenji; Iwasa, Mayumi; Wakakura, Masato; Tomita, Goji

    2012-01-01

    The purpose of this study was to evaluate the effects of benzalkonium (BAK)-free travoprost monotherapy administered for 3 years on intraocular pressure and visual field performance. The intraocular pressure of 76 patients with normal tension glaucoma was monitored every 1-3 months. A Humphrey visual field test was performed every 6 months after treatment and compared with the results before treatment. Visual field performance was also evaluated by trend and event analysis. Thirty cases discontinued within 3 years. Mean intraocular pressure after 3 years of travoprost treatment (14.1 ± 2.4 mmHg) was significantly lower than that before treatment (16.8 ± 2.6 mmHg, P trend analysis and five patients (13.9%) by event analysis. Treatment was discontinued in six cases (7.9%) due to the appearance of adverse reactions. BAK-free travoprost monotherapy was effective in reducing intraocular pressure for at least 3 years; however, visual field performance worsened in 2.8%-13.9% of patients with normal tension glaucoma.

  10. Evaluation of tension stiffening effect on the crack width calculation of flexural RC members

    Directory of Open Access Journals (Sweden)

    Said M. Allam

    2013-06-01

    Full Text Available Building codes consider the tension stiffening when calculating the crack width of the flexural members. A simple analytical procedure is proposed for the determination of forces, stresses and strains acting on a reinforced concrete section subjected to flexure considering the concrete contribution in tension up to tensile concrete strain corresponding to the cracking strength of concrete. This analytical method gives the minimum value (lower bound of tension stiffening. Also, a commercial Finite Element Program (ABAQUS 2007 was used to perform non-linear analysis in order to evaluate the total contribution of the tensioned concrete in carrying loads which may be considered as the upper bound of tension stiffening. In addition, a comparison is carried out among the different codes using four reinforced concrete rectangular models to compare and evaluate the tension stiffening with proposed analytical lower bound tension stiffening and upper bound as obtained by ABAQUS. The models include different percentages of flexural steel ratio. The comparison revealed that the codes’ equations always consider tension stiffening lying between lower and upper bound of tension stiffening proposed in this study. Also, the study showed that the tension stiffening decreases with the increase of the percentage of the flexural reinforcement ratio.

  11. Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

    Directory of Open Access Journals (Sweden)

    Deng Zhenghua

    2013-03-01

    Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.

  12. Effect of tendon tensioning: an in vitro study in porcine extensor tendons.

    Science.gov (United States)

    Figueroa, David; Calvo, Rafael; Vaisman, Alex; Meleán, Patricio; Figueroa, Francisco

    2010-06-01

    Graft tensioning is a controversial issue in anterior cruciate ligament reconstruction (ACLR) that has not achieved consensus between peers. The purpose of this study is to determine if after tensioning tendon length and resistance to maximal load changes. We performed an in vitro study with 50 porcine extensors tendons. The first group (P=25) was tensioned with 80 N (19.97 lb) for 10 min, using an ACL graft preparation board. The second group (C=25) was used as control and was not tensioned. The average initial (groups P and C) and post tensioning tendon length (group C) were measured; the average initial and post tensioning tendon diameter were measured as well. All samples were fixated in a tube-clamp system connected to a tension sensor. The samples were stressed with continuous and progressive tension until ultimate failure at maximum load (UFML) occurs. The initial mean length was: P before tensioning=13.4 mm+/-1.4 mm (range 10.5-16.5); P after tensioning=13.8 mm+/-1.4 mm (range 11.5-16.5); C=13 mm+/-1.35 mm (p=0.005). The mean diameter was: P=5.6 mm (4.5-6); C=5.5 mm (range 4.5-6) (p>0.05). The UFML was: P=189.7 N (114-336); C=229.9 N (143-365) (p=0.029). Tendon tensioning with 80 N for 10 min produced 3% average elongation. These could be beneficial in ACLR since tendon tensioning decreases elongation of the graft after fixation. Regardless, tendon tensioning is not innocuous since it diminishes their resistance when continuously stressed until complete failure occurs.

  13. Effect of temperature, viscosity and surface tension on gelatine structures produced by modified 3D printer

    Science.gov (United States)

    Kalkandelen, C.; Ozbek, B.; Ergul, N. M.; Akyol, S.; Moukbil, Y.; Oktar, F. N.; Ekren, N.; Kılıc, O.; Kılıc, B.; Gunduz, O.

    2017-12-01

    In the present study, gelatine scaffolds were manufactured by using modified 3D (3 Dimensional) printing machine and the effect of different parameters on scaffold structure were investigated. Such as; temperature, viscosity and surface tension of the gelatine solutions. The varying of gelatine solutions (1, 3, 5, 10, 15 and 20 wt.%) were prepared and characterized. It has been detected that, viscosity of those solutions were highly influenced by temperature and gelatine concentration. Specific CAD (Computer Assistant Design) model which has 67% porosity and original design were created via computer software. However, at high temperatures gelatine solutions caused like liquid but at the lower temperatures were observed the opposite behaviour. In addition to that, viscosity of 1,3,5 wt.% solutions were not enough to build a structure and 20 wt.% gelatine solution too hard to handle, because of the sudden viscosity changes with temperature. Even though, scaffold of the 20 wt.% gelatine solution printed hardly but it was observed the best printed solutions, which were 10 and 15 wt.% gelatine solutions. As a result, 3D printing of gelatine were found the values of the best temperature, viscosity, surface tension and gelatine concentration such as 25-35 °C, 36-163 cP, 46-59 mN/m and 15 wt.% gelatine concentration respectively.

  14. Effects of surface tension and viscosity on the forming and transferring process of microscale droplets

    Science.gov (United States)

    Chen, Shulei; Liu, Kun; Liu, Cunbin; Wang, Dongyang; Ba, Dechun; Xie, Yuanhua; Du, Guangyu; Ba, Yaoshuai; Lin, Qiao

    2016-12-01

    Surface tension and viscosity act as important roles on the fluid flow in microchannel channels. In order to understand the influencing mechanism, three dimensional numerical simulations as well as experimental investigations were carried out on the slug formation and transfer in a rectangle T-junction microchannel. The simulation showed that the increasing Capillary number (Ca) resulted in the decreasing slug volume. Due to the existence of film thickness and corner flow, the characteristic length of slug was not the same trend completely. The results also showed that the pressure of junction point fluctuated periodically in the process of slug formation, which can reflect the slug formation period and the effect of the various conditions on pressure change. Two other pressure monitoring points were located in vertical channel and main channel and they monitored the pressure of two phase flow respectively. The increasing surface tension resulted in an increasing of total pressure, the interface pressure drop of two phases and the period of slug formation. The frequency of slug formation and two phases total pressure increased with the viscosity of continuous phase.

  15. Outflow and plasma acceleration in Titan's induced magnetotail: Evidence of magnetic tension forces

    OpenAIRE

    Romanelli, N.; Modolo, Ronan; Dubinin, E.; Berthelier, Jean-Jacques; Bertucci, C.; Wahlund, J. E.; Leblanc, François; Canu, P.; Edberg, Niklas JT; Waite, H.; Kurth, W. S.; Gurnett, D.; Coates, A.; Dougherty, M.

    2014-01-01

    International audience; Cassini plasma wave and particle observations are combined with magnetometer measurements to study Titan's induced magnetic tail. In this study, we report and analyze the plasma acceleration in Titan's induced magnetotail observed in flybys T17, T19 and T40. Radio and Plasma Wave Science (RPWS) observations show regions of cold plasma with electron densities between 0.1 and a few tens of electrons per cubic centimeter. The Cassini Plasma Spectrometer-Ion Mass Spectrome...

  16. Surface tension induced convection in encapsulated liquid metals in microgravity: Apollo--Soyuz test project experiment No. MA-041. [Pb/Pb--0. 05 at. % Au liquid diffusion couple

    Energy Technology Data Exchange (ETDEWEB)

    Reed, R.E.; Adair, H.L.; Uelhoff, W.

    1976-12-01

    One objective of the Apollo--Soyuz Test Project (ASTP) was to conduct scientific experiments in a gravity-free environment to permit the study of melting and solidification processes as well as liquid processes in space. It has been shown by Skylab experiments that surface driven convection caused by temperature gradients (Marangoni effect) is negligibly small. This experiment was designed to determine the extent of surface tension induced convection caused by a steplike compositional variation in a liquid metal. This report describes preliminary results obtained for ASTP Experiment No. MA-041 entitled ''Surface Tension Induced Convection in Encapsulated Liquid Metal in Microgravity.'' The liquid diffusion couple comprised Pb/Pb--0.05 at. percent Au.

  17. Dynamic Effects of Anchor Positional Tolerance on Tension Moored Floating Wind Turbine

    Science.gov (United States)

    Wright, Christopher; Pakrashi, Vikram; Murphy, Jimmy

    2016-09-01

    For water depths greater than 60m floating wind turbines will become the most economical option for generating offshore wind energy. Tension mooring stabilised units are one type of platform being considered by the offshore wind energy industry. The complex mooring arrangement used by this type of platform means that the dynamics are greatly effected by offsets in the positioning of the anchors. This paper examines the issue of tendon anchor position tolerances. The dynamic effects of three positional tolerances are analysed in survival state using the time domain FASTLink. The severe impact of worst case anchor positional offsets on platform and turbine survivability is shown. The worst anchor misposition combinations are highlighted and should be strongly avoided. Novel methods to mitigate this issue are presented.

  18. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids

    Science.gov (United States)

    Hu, Bin; Kieweg, Sarah L.

    2012-01-01

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability. PMID:23687391

  19. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids.

    Science.gov (United States)

    Hu, Bin; Kieweg, Sarah L

    2012-07-15

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability.

  20. Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Pia [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark); Department of Neurosurgery, University of Bern, CH-3010 Bern (Switzerland); Gramsbergen, Jan-Bert; Zimmer, Jens [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark); Widmer, Hans R. [Department of Neurosurgery, University of Bern, CH-3010 Bern (Switzerland); Meyer, Morten, E-mail: MMeyer@health.sdu.dk [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark)

    2011-07-15

    Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than in high oxygen cultures. Low oxygen during FGF2-mediated expansion resulted also in a significant increase in tyrosine hydroxylase-immunoreactive (TH-ir) dopaminergic neurons as compared to high oxygen tension, but no corresponding effect was observed for dopamine release into the culture medium. However, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH enzyme activity, which may explain the elevated dopamine levels. Our findings demonstrate that modulation of oxygen tension is a recognizable factor for in vitro expansion and dopaminergic differentiation of rat embryonic midbrain precursor cells.

  1. Surface tension effects on the onset of double-diffusive convection

    Science.gov (United States)

    Chen, C. F.

    1992-01-01

    Experiments have been carried out to determine the critical thermal Rayleigh number for onset of convection in a horizontal layer of density-stratified fluid with a free surface when heated from below. Three different aqueous solutions were used: salt, glycerol, and acetic acid. The rates of change in surface tension with concentration for these three solutions are positive, nearly zero, and negative, respectively. Compared to the rigid-rigid boundaries, the critical thermal Rayleigh number was found to be larger by 11.2 percent for the salt solution and smaller by 10.0 percent for the glycerol solution. With the acetic acid solution, however, the effect of the free surface was found to be negligible.

  2. Effect of Reinforcement Architecture on Fracture of Selectively Reinforced Metallic Compact Tension Specimens

    Science.gov (United States)

    Abada, Christopher H.; Farley, Gary L.; Hyer, Michael W.

    2006-01-01

    A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens is performed. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the non-reinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement.

  3. The effect of corneal biomechanical properties on rebound tonometer in patients with normal-tension glaucoma.

    Science.gov (United States)

    Shin, Jonghoon; Lee, Ji-Woong; Kim, Eun-Ah; Caprioli, Joseph

    2015-01-01

    To evaluate the effects of corneal biomechanical properties on intraocular pressure (IOP) measured with the ICare, and to compare IOP readings obtained with ICare, Ocular Response Analyzer (ORA), and Goldmann applanation tonometry (GAT) in normal-tension glaucoma (NTG) and normal subjects. Prospective, cross-sectional, comparative study. IOP was measured with ICare, ORA, and GAT. All subjects had corneal hysteresis (CH) and corneal resistance factor (CRF), which were measured with ORA; and central corneal thickness (CCT), axial length, spherical equivalent, and keratometry. This study enrolled 97 eyes of 97 NTG patients and 89 eyes of 89 normal subjects. CCT, CH, and CRF in NTG patients were significantly lower than those in normal subjects (P = .033, P = .006, and P = .003). The difference in IOP between techniques was highly significant in NTG patients (P biomechanical characteristics in NTG can cause ICare to underestimate IOP. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Effects of tafluprost treatment for 3 years in patients with normal-tension glaucoma

    Directory of Open Access Journals (Sweden)

    Inoue K

    2013-07-01

    Full Text Available Kenji Inoue,1 Ayumi Tanaka,1 Goji Tomita2 1Inouye Eye Hospital, 22nd Department of Ophthalmology, Toho University School of Medicine, Tokyo, Japan Purpose: To evaluate the effects of tafluprost treatment for 3 years on intraocular pressure (IOP and visual field performance. Methods: The IOP of 55 patients with normal-tension glaucoma was monitored every 1–3 months for 3 years. The Humphrey visual field test was performed every 6 months after treatment and results compared with before-treatment results. Visual field performance was also evaluated by trend and event analysis. Results: After 3 years’ tafluprost single-use vials treatment, the IOP (12.8 ± 2.8 mmHg [mean ± standard deviation] was significantly lower than before treatment (15.7 ± 2.2 mmHg; P < 0.0001. When comparing before-treatment Humphrey visual field test findings with those after 3 years of treatment, no change was found in the mean deviation and pattern standard deviation. Visual field performance had worsened in four patients and three patients according to trend analysis and event analysis, respectively. Adverse reactions appeared in ten cases and one patient (1.8% discontinued treatment due to an adverse reaction. Conclusion: Tafluprost single-use vials treatment was effective in reducing IOP over the 3 years of this study, but visual field performance worsened by 10.3%–13.8% in patients with normal-tension glaucoma. Safety was satisfactory. Keywords: intraocular pressure, visual field, trend analysis, event analysis

  5. Effects of BAK-free travoprost treatment for 3 years in patients with normal tension glaucoma

    Directory of Open Access Journals (Sweden)

    Inoue K

    2012-08-01

    Full Text Available Kenji Inoue,1 Mayumi Iwasa,1 Masato Wakakura,1 Goji Tomita21Inouye Eye Hospital, 2Toho University Ohashi Medical Center, Tokyo, JapanBackground: The purpose of this study was to evaluate the effects of benzalkonium (BAK-free travoprost monotherapy administered for 3 years on intraocular pressure and visual field performance.Methods: The intraocular pressure of 76 patients with normal tension glaucoma was monitored every 1–3 months. A Humphrey visual field test was performed every 6 months after treatment and compared with the results before treatment. Visual field performance was also evaluated by trend and event analysis.Results: Thirty cases discontinued within 3 years. Mean intraocular pressure after 3 years of travoprost treatment (14.1 ± 2.4 mmHg was significantly lower than that before treatment (16.8 ± 2.6 mmHg, P ‹ 0.0001. There was no change in the mean deviation and pattern standard deviation as measured by Humphrey visual field test after 3 years of treatment compared with before treatment. Visual field performance was worse in one patient (2.8% by trend analysis and five patients (13.9% by event analysis. Treatment was discontinued in six cases (7.9% due to the appearance of adverse reactions.Conclusion: BAK-free travoprost monotherapy was effective in reducing intraocular pressure for at least 3 years; however, visual field performance worsened in 2.8%–13.9% of patients with normal tension glaucoma.Keywords: BAK-free travoprost, intraocular pressure, visual field, trend analysis, event analysis

  6. Effect of cardiogenic gas mixing on arterial O2 and CO2 tensions during breath holding.

    Science.gov (United States)

    Kelly, S M; Brancatisano, A P; Engel, L A

    1987-04-01

    To examine the effect of cardiogenic gas mixing on gas exchange we measured arterial tension of O2 (PaO2) and arterial tension of CO2 (PaCO2) during 3- to 5-min breath holds (BH) before and after infusing 50 ml of saline into the pericardial space (PCF) of seven anesthetized, paralyzed, mechanically ventilated dogs. During BH the ventilator was disconnected and a bias flow of 50% O2 at 4-5 l/min was delivered through the side ports of a small catheter whose tip was positioned 1 cm cephalad of the carina. Paired runs, alternately with and without PCF, were performed in triplicate in each dog. Initial PaO2 was similar for control runs [81 +/- 3 mmHg (SE)] and PCF runs (78 +/- 3 mmHg; P greater than 0.1). After 3-min BH, PaO2 in PCF runs (33 +/- 3 mmHg) was less than that in control runs (58 +/- 4 mmHg) (P less than 0.001). In contrast, the pattern of PaCO2 during BH did not differ with PCF. After 3-min BH, PaCO2 was 49 +/- 3 mmHg with PCF and 49 +/- 2 mmHg in the control runs (P greater than 0.7). In two dogs, repeated 50-ml reductions in lung volume, produced by rib cage compression, did not alter the time course of PaO2 during BH. Although cardiac output decreased slightly with PCF, hemodynamic changes due to PCF were unlikely to account for the observed fall in PaO2. Our results indicate a substantial effect of cardiogenic gas mixing on O2 uptake when tracheal gas is O2 enriched during breath holding.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Investigating the effects of strap tension during non-invasive ventilation mask application: a combined biomechanical and biomarker approach

    Directory of Open Access Journals (Sweden)

    Worsley PR

    2016-11-01

    Full Text Available Peter R Worsley, George Prudden, George Gower, Dan L Bader Southampton General Hospital, Clinical Academic Facility, Faculty of Health Sciences, University of Southampton, Southampton, UK Abstract: Non-invasive ventilation is commonly used for respiratory support. However, in some cases, mask application can cause pressure ulcers to specific features of the face, resulting in pain and reduced quality of life for the individual. This study investigated the effects of mask strap tension on the biomechanical and biomarker responses at the skin interface. Healthy participants (n=13 were recruited and assigned two different masks in a random order, which were fitted with three strap conditions representing increments of 5 mm to increase tension. Masks were worn for 10 minutes at each tension followed by a 10-minute refractory period. Assessment at the device–skin interface included measurements of pressures at the nose and cheeks, temperature and humidity, a selection of inflammatory cytokine concentrations collected from sebum and scores of comfort. The results indicated significantly higher interface pressures at the bridge of the nose compared to the cheeks for both masks (p<0.05, with nasal interface pressures significantly increasing with elevated strap tension (p<0.05. One inflammatory cytokine, IL-1α, increased following mask application at the highest tension, with median increases from baselines ranging from 21 to 33%. The other cytokines revealed a less consistent trend with strap tension. The participants reported statistically greater discomfort during elevated strap tension. Temperature and humidity values under the mask were elevated from ambient conditions, although no differences were observed between mask type or strap tension. The bony prominence on the bridge of the nose represented a vulnerable area of skin during respiratory mask application. This study has shown that mask strap tension has a significant effect on the

  8. Effects of Environmental Oxygen Content and Dissolved Oxygen on the Surface Tension and Viscosity of Liquid Nickel

    Science.gov (United States)

    SanSoucie, M. P.; Rogers, J. R.; Kumar, V.; Rodriguez, J.; Xiao, X.; Matson, D. M.

    2016-07-01

    The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has recently added an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled in the range from approximately 10^{-28} {to} 10^{-9} bar, while in a vacuum atmosphere. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, has a PID-based current loop and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects on surface tension and viscosity by oxygen partial pressure in the surrounding environment and the melt dissolved oxygen content will be evaluated, and the results will be presented. The surface tension and viscosity will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension and viscosity will be measured using the oscillating droplet method.

  9. Measurement of effective alveolar carbon dioxide tension during spontaneous breathing in normal subjects and patients with chronic airways obstruction.

    Science.gov (United States)

    Jordanoglou, J; Koulouris, N; Kyroussis, D; Rapakoulias, P; Vassalos, P; Madianos, J

    1995-03-01

    The measurement of effective alveolar carbon dioxide tension (PA-CO2eff) is still a matter of debate. It has, however, become common practice to use arterial instead of alveolar CO2 tension for computing alveolar oxygen tension (PAO2) and physiological dead space, not only in normal subjects but also in patients. The purpose of this study was to estimate alveolar CO2 tension during spontaneous breathing with a new bedside technique which is simple and non-invasive, and to compare these values with arterial CO2 tension measured in normal subjects and patients with chronic airways obstruction. The subjects breathed quietly through the equipment assembly (mouthpiece, monitoring ring, Fleisch transducer head) connected to a pneumotachograph and a fast response infrared CO2 analyser. The method is a computerised calculation of the volume weighted effective alveolar CO2 tension obtained from the simultaneously recorded expiratory flow and CO2 concentration versus time curves. An arterial blood sample was taken to measure PaCO2 for comparison during the study. The results showed a mean difference (PACO2eff-PaCO2) of -0.205 kPa in 20 normal subjects and -0.460 kPa in 46 patients. The 95% confidence interval of the bias was -0.029 to -0.379 kPa in normal subjects and -0.213 to -0.707 kPa in patients. The limits of agreement between PACO2eff and PaCO2 were 0.526 to -0.935 in normal subjects and 1.170 to -2.088 in patients. The volume weighted effective alveolar PCO2 in normal subjects and patients with chronic airways obstruction is lower than the arterial PCO2 and is recommended as a better estimate in the classical equations for estimating dead space and intrapulmonary shunt.

  10. Effect of psychological tension on pedestrian counter flow via an extended cost potential field cellular automaton model

    Science.gov (United States)

    Li, Xingli; Guo, Fang; Kuang, Hua; Zhou, Huaguo

    2017-12-01

    Psychology tells us that the different level of tension may lead to different behavior variation for individuals. In this paper, an extended cost potential field cellular automaton is proposed to simulate pedestrian counter flow under an emergency by considering behavior variation of pedestrian induced by psychological tension. A quantitative formula is introduced to describe behavioral changes caused by psychological tension, which also leads to the increasing cost of discomfort. The numerical simulations are performed under the periodic boundary condition and show that the presented model can capture some essential features of pedestrian counter flow, such as lane formation and segregation phenomenon for normal condition. Furthermore, an interesting feature is found that when pedestrians are in an extremely nervous state, a stable lane formation will be broken by a disordered mixture flow. The psychological nervousness under an emergency is not always negative to moving efficiency and a moderate level of tension will delay the occurrence of jamming phase. In addition, a larger asymmetrical ratio of left walkers to right walkers will improve the critical density related to the jamming phase and retard the occurrence of completely jammed phase. These findings will be helpful in pedestrian control and management under an emergency.

  11. The effect of age and sex of normal volunteers upon the transcutaneous oxygen tension in the lower limb.

    Science.gov (United States)

    Dowd, G S; Linge, K; Bentley, G

    1983-02-01

    The transcutaneous oxygen monitor, developed as a non-invasive method of measuring arterial oxygen tension in neonates, has recently been applied to measurement of skin ischaemia in peripheral vascular disease. Since peripheral vascular disease occurs in older age groups and more commonly in men than women, the effects of age and sex on the transcutaneous oxygen tension in the lower limb have been investigated. Two hundred and five normal volunteers of both sexes with a wide age range had measurements taken at a fixed point in the lower limb under similar conditions. The results showed no significant correlation between either the age or sex of the individual when compared to the transcutaneous oxygen tension.

  12. Vortex-induced vibration of a tension leg platform tendon: multi-mode limit cycle oscillations

    Science.gov (United States)

    Datta, Nabanita

    2017-11-01

    This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, analyzed using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation (lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.

  13. Vortex-induced vibration of a tension leg platform tendon: Multi-mode limit cycle oscillations

    Science.gov (United States)

    Datta, Nabanita

    2017-12-01

    This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, analyzed using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation (lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.

  14. Low-frequency electrical stimulation induces long-term depression in patients with chronic tension-type headache

    DEFF Research Database (Denmark)

    Lindelof, Kim; Jung, Kerstin; Ellrich, Jens

    2010-01-01

    Repetitive low-frequency electrical stimulation (LFS) induces pain inhibition in healthy volunteers and in animals, but it is unknown whether it has an analgesic effect in patients with headache. The aim of this study was to investigate if LFS could induce prolonged pain inhibition, called long-t...

  15. Enhanced dopaminergic differentiation of human neural stem cells by synergistic effect of Bcl-xL and reduced oxygen tension

    DEFF Research Database (Denmark)

    Krabbe, Christina; Courtois, Elise; Jensen, Pia

    2009-01-01

    Neural stem cells constitute a promising source of cells for transplantation in Parkinson's disease, but a protocol for controlled dopaminergic differentiation is not yet available. Here we investigated the effect of the anti-apoptotic protein Bcl-x(L) and oxygen tension on dopaminergic different...

  16. Effects of different initial bundle tensioning strategies on the outcome of double-bundle ACL reconstruction: a cohort study

    Directory of Open Access Journals (Sweden)

    Muneta Takeshi

    2011-07-01

    Full Text Available Abstract Background This study was performed to investigate the effects of different strategies and initial tension applied to each one of the bundles, antero-medial (AM and postero-lateral (PL, on clinical outcome in double bundle (DB ACL reconstruction. Methods One hundred fifty-one primary unilateral DB ACL reconstructions performed by a single surgeon from 1994 through 2002 were included in the study with a follow-up of at least 24 months. They were divided in the following 3 groups: Group I - Higher initial tension applied manually in the AM bundle compared to PL. II - Higher tension applied in the PL bundle compared to AM. III - The 2 bundles were attempted to be equally tensioned. All fixations were performed in 30 degrees of flexion. Group I = 59 patients, group II = 53 patients and group III = 39 patients. The groups had no statistical differences concerning demographic distribution. Clinical outcome was retrospectively evaluated by use of knee range of motion, manual knee laxity tests, KT-1000, Lysholm knee scale, subjective recovery scale and sports performance recovery scale. The differences of data were analyzed among the three groups. Results Group I showed a significant extension deficit compared with groups II and III. ANOVA revealed a significant difference of anterior laxity measured by the KT-1000 (average KT difference of 2.1, 2.1 and 1.2 mm in Group I, II and III, respectively. A statistical difference was found among the three groups regarding subjective and sports performance recovery scales with Group II showing higher scores in recovery than Group I. Conclusions The current clinical study does not recommend manual maximum of initial tension applied to the anteromedial or posterolateral bundles with graft tension imbalance at 30 degrees of flexion in double-bundle ACL reconstruction to achieve a better clinical outcome.

  17. Effects of specimen size and crack depth ratio on calibration curves for modified compact tension specimens

    Czech Academy of Sciences Publication Activity Database

    Seitl, Stanislav; Viszlay, V.; Cifuentes, H.; Canteli, A.

    2015-01-01

    Roč. 15, č. 2 (2015) ISSN 1804-4824 Institutional support: RVO:68081723 Keywords : Modified compact tension test * fracture * concrete * core drill * stress intensity factor Subject RIV: JL - Materials Fatigue, Friction Mechanics

  18. Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

    DEFF Research Database (Denmark)

    Stefánsson, E; Jensen, P K; Eysteinsson, T

    1999-01-01

    To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture....

  19. Optic nerve oxygen tension in pigs and the effect of carbonic anhydrase inhibitors

    DEFF Research Database (Denmark)

    Stefánsson, E; Jensen, P K; Eysteinsson, T

    1999-01-01

    To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture.......To evaluate how the oxygen tension of the optic nerve (ONP(O)2) is affected by the administration of the carbonic anhydrase inhibitors dorzolamide and acetazolamide and by alterations in oxygen and carbon dioxide in the breathing mixture....

  20. Computational Study of Surface Tension and Wall Adhesion Effects on an Oil Film Flow Underneath an Air Boundary Layer

    Science.gov (United States)

    Celic, Alan; Zilliac, Gregory G.

    1998-01-01

    The fringe-imaging skin friction (FISF) technique, which was originally developed by D. J. Monson and G. G. Mateer at Ames Research Center and recently extended to 3-D flows, is the most accurate skin friction measurement technique currently available. The principle of this technique is that the skin friction at a point on an aerodynamic surface can be determined by measuring the time-rate-of-change of the thickness of an oil drop placed on the surface under the influence of the external air boundary layer. Lubrication theory is used to relate the oil-patch thickness variation to shear stress. The uncertainty of FISF measurements is estimated to be as low as 4 percent, yet little is known about the effects of surface tension and wall adhesion forces on the measured results. A modified version of the free-surface Navier-Stokes solver RIPPLE, developed at Los Alamos National Laboratories, was used to compute the time development of an oil drop on a surface under a simulated air boundary layer. RIPPLE uses the volume of fluid method to track the surface and the continuum surface force approach to model surface tension and wall adhesion effects. The development of an oil drop, over a time period of approximately 4 seconds, was studied. Under the influence of shear imposed by an air boundary layer, the computed profile of the drop rapidly changes from its initial circular-arc shape to a wedge-like shape. Comparison of the time-varying oil-thickness distributions computed using RIPPLE and also computed using a greatly simplified numerical model of an oil drop equation which does not include surface tension and wall adhesion effects) was used to evaluate the effects of surface tension on FISF measurement results. The effects of surface tension were found to be small but not necessarily negligible in some cases.

  1. Effect of water on nanomechanics of bone is different between tension and compression

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Jitin; Park, Jun-Sang; Almer, Jonathan; Wang, Xiaodu

    2016-04-01

    Water, an important constituent in bone, resides in different compartments in bone matrix and may impose significant effects on its bulk mechanical properties. However, a clear understanding of the mechanistic role of water in toughening bone is yet to emerge. To address this issue, this study used a progressive loading protocol, coupled with measurements of in situ mineral and collagen fibril deformations using synchrotron X-ray diffraction techniques. Using this unique approach, the contribution of water to the ultrastructural behavior of bone was examined by testing bone specimens in different loading modes (tension and compression) and hydration states (wet and dehydrated). The results indicated that the effect of water on the mechanical behavior of mineral and collagen phases at the ultrastructural level was loading mode dependent and correlated with the bulk behavior of bone. Tensile loading elicited a transitional drop followed by an increase in load bearing by the mineral phase at the ultrastructural level, which was correlated with a strain hardening behavior of bone at the bulk level. Compression loading caused a continuous loss of load bearing by the mineral phase, which was reflected at the bulk level as a strain softening behavior. In addition, viscous strain relaxation and pre-strain reduction were observed in the mineral phase in the presence of water. Taken together, the results of this study suggest that water dictates the bulk behavior of bone by altering the interaction between mineral crystals and their surrounding matrix.

  2. Effect of pH on dynamic and equilibrium surface tension of dissolve organic matter

    Science.gov (United States)

    Arye, Gilboa; Trifonov, Pavel; Ilani, Talli

    2014-05-01

    Dissolved organic matter (DOM) in the terrestrial environment may originate from the decomposition of soil organic matter accumulated from the degradation of vegetative residues, the release of root exudates, the lysis of microorganisms and addition of organic wastes, such as livestock manure, biosolids, and different composted organic residues, or from irrigation with wastewater. The structure of DOM macromolecules is known to vary with the following aqueous solution properties: ionic strength, the nature of the inorganic ions, pH and dissolved organic carbon (DOC) concentration. In aqueous solution, the DOM molecules are amphiphilic, that is, it possesses both hydrophilic and hydrophobic functional groups in the same molecule. This simultaneous presence, gave rise to the conceptual surfactant like model for DOM which has been studies in conjunction with the equilibrium surface tension at the liquid-air interface (STeq, mN/m). Measurements of STeq of DOM solution were reported in a relatively small number of studies for the conditions of the aqueous solution (e.g., temperature, pH, ionic strength, the valence of the metal ions, and DOC concentration). All studies demonstrate the decrease in STeq with increase aqueous concentration of the DOC. The effect of pH, however, exhibit contradictory results. Specifically, for a given DOC concentration, the patterns reported for STeq versus pH were different. With increasing pH values, STeq has been reported to decrease, increase or exhibit a minimum. These contradictory results have been attributed to the different DOC concentration examined in each of the studies. In current study we hypothesized that the inconsistent results of STeq vs. pH may also stem from the adsorption kinetics of the DOM amphiphilic molecules at the liquid air interface, which can be evaluated form dynamic surface tension measurements (STt). The STt is approaching STeq values and commonly exhibiting an exponential decay pattern. If for different p

  3. The effects of stress-tension on depression and anxiety symptoms: evidence from a novel twin modelling analysis.

    Science.gov (United States)

    Davey, C G; López-Solà, C; Bui, M; Hopper, J L; Pantelis, C; Fontenelle, L F; Harrison, B J

    2016-11-01

    Negative mood states are composed of symptoms of depression and anxiety, and by a third factor related to stress, tension and irritability. We sought to clarify the nature of the relationships between the factors by studying twin pairs. A total of 503 monozygotic twin pairs completed the Depression Anxiety Stress Scales (DASS), an instrument that assesses symptoms of depression, anxiety and stress-tension. We applied a recently developed twin regression methodology - Inference about Causation from Examination of FAmiliaL CONfounding (ICE FALCON) - to test for evidence consistent with the existence of 'causal' influences between the DASS factors. There was evidence consistent with the stress-tension factor having a causal influence on both the depression (p anxiety factors (p = 0.001), and for the depression factor having a causal influence on the anxiety factor (p stress-tension in the structure of negative mood states, and that interventions that target it may be particularly effective in reducing depression and anxiety symptoms.

  4. Effects of Voice Therapy on Muscle Tension Dysphonia: A Systematic Literature Review.

    Science.gov (United States)

    da Cunha Pereira, Gabriela; de Oliveira Lemos, Isadora; Dalbosco Gadenz, Camila; Cassol, Mauriceia

    2017-07-21

    The present study aimed to carry out a systematic review of the effects of voice therapy on individuals diagnosed with muscle tension dysphonia (MTD) or hyperfunctional dysphonia. This is a systematic literature review on the databases Medline (via PubMed), Cochrane Library, Scopus, and Lilacs using a search strategy related to the theme of the study. The selection included clinical trials that assessed the effects of speech therapy intervention on patients diagnosed with MTD or hyperfunctional dysphonia published over the last 10 years in Portuguese, English, or Spanish. The Physiotherapy Evidence-Based Database (PEDro) Scale was used to assess the methodology of the studies. Of the 634 publications, 12 studies were included in this review, of which three were excluded due to a low score on the PEDro Scale, resulting in a final number of nine publications. Regarding the techniques approached, semioccluded vocal tract exercises (22.22%), nasal sound and frequency modulation (22.22%), maximum phonation time (MPT) technique and vocal hygiene (11.11%), vocal function exercises (11.11%), respiratory exercises along with phonoarticulatory sounds (11.11%), manual laryngeal therapy (11.11%), and manual laryngeal therapy associated with respiratory exercises (11.11%) were identified. These techniques promoted the following effects: improvement in intraoral and subglottal pressure, positive alterations in the glottal contact quotient, significant changes in fundamental frequency measures, increased MPT, and reduced voice roughness. Methodology was identified to be a shortcoming in the studies. The clinical trials reviewed showed positive results in using the therapeutic techniques selected in the speech therapy approach. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  5. The effect of surface tension on steadily translating bubbles in an unbounded Hele-Shaw cell.

    Science.gov (United States)

    Green, Christopher C; Lustri, Christopher J; McCue, Scott W

    2017-05-01

    New numerical solutions to the so-called selection problem for one and two steadily translating bubbles in an unbounded Hele-Shaw cell are presented. Our approach relies on conformal mapping which, for the two-bubble problem, involves the Schottky-Klein prime function associated with an annulus. We show that a countably infinite number of solutions exist for each fixed value of dimensionless surface tension, with the bubble shapes becoming more exotic as the solution branch number increases. Our numerical results suggest that a single solution is selected in the limit that surface tension vanishes, with the scaling between the bubble velocity and surface tension being different to the well-studied problems for a bubble or a finger propagating in a channel geometry.

  6. Changes of blood flow, oxygen tension, action potential and vascular permeability induced by arterial ischemia or venous congestion on the spinal cord in canine model.

    Science.gov (United States)

    Kobayashi, Shigeru; Yoshizawa, Hidezo; Shimada, Seiichiro; Guerrero, Alexander Rodríguez; Miyachi, Masaya

    2013-01-01

    It is generally considered that the genesis of myelopathy associated with the degenerative conditions of the spine may result from both mechanical compression and circulatory disturbance. Many references about spinal cord tissue ischemic damage can be found in the literature, but not detailed studies about spinal cord microvasculature damage related to congestion or blood permeability. This study investigates the effect of ischemia and congestion on the spinal cord using an in vivo model. The aorta was clamped as an ischemia model of the spinal cord and the inferior vena cava was clamped as a congestion model at the 6th costal level for 30 min using forceps transpleurally. Measurements of blood flow, partial oxygen pressure, and conduction velocity in the spinal cord were repeated over a period of 1 h after release of clamping. Finally, we examined the status of blood-spinal cord barrier under fluorescence and transmission electron microscope. Immediately after clamping of the inferior vena cava, the central venous pressure increased by about four times. Blood flow, oxygen tension and action potential were more severely affected by the aorta clamping; but this ischemic model did not show any changes of blood permeability in the spinal cord. The intramedullar edema was more easily produced by venous congestion than by arterial ischemia. In conclusions, venous congestion may be a preceding and essential factor of circulatory disturbance in the compressed spinal cord inducing myelopathy. Copyright © 2012 Orthopaedic Research Society.

  7. Role of extracellular and intracellular acidosis for hypercapnia-induced inhibition of tension of isolated rat cerebral arteries

    DEFF Research Database (Denmark)

    Tian, R; Vogel, P; Lassen, N A

    1995-01-01

    Ho was measured with a glass electrode. In all studies, Ca(2+)-dependent basal tension (in the absence of any agonist) and tension in the presence of arginine vasopressin were investigated. Control solution was physiological saline bubbled with 5% CO2 and containing 25 mmol/L HCO3- (pH 7.45 to 7.50). Induction......The importance of smooth muscle cell pHi and pHo for the hypercapnic vasodilation of rat cerebral arteries was evaluated in vitro. Vessel segments were mounted in a myograph for isometric tension recording; pHi was measured by loading the smooth muscle cells with the fluorescent dye BCECF, and p...

  8. Botulinum toxin A is effective to treat tension-type headache caused by hemifacial spasm.

    Science.gov (United States)

    Mizuma, Atsushi; Nagata, Eiichiro; Yasuda, Takashi; Kouchi, Maiko; Nakayama, Taira; Honma, Kazunari; Tokuoka, Kentaro; Kitagawa, Yasuhisa; Nogawa, Shigeru; Takizawa, Shunya

    2017-10-01

    We examined the relationship between hemifacial spasm (HFS; a form of cranio-cervical dystonia) and chronic primary headache, including tension-type headache (TTH). We also examined whether botulinum toxin A (BoNT/A) therapy for HFS ameliorates concomitant TTH. Fifty-one HFS patients receiving BoNT/A therapy were recruited. Patients' characteristics (including age, gender, chronic headache history, exercise habits, stiff neck, cervical spondylolysis history), stress factors, worsening/new onset of headache associated with HFS, and dose of BoNT/A were examined. We diagnosed headache types according to The International Classification of Headache Disorders, 3rd edition, beta. Numerical Rating Scale (NRS) and Headache Impact Test-6 (HIT-6) scores for headache severity were compared between the 6-week baseline before BoNT/A therapy and 6-week follow-up after BoNT/A therapy. Of 51 patients with HFS, 17 (33.3%) reported worsening or new onset of headache (especially TTH) associated with HFS (Group-S), and 34 were not aware of headache (Group-N). Twelve patients (70.6%) in group-S reported improvement of headache after BoNT/A therapy. NRS (from 7 [5-9] to 0 [0-5], p<0.01) and HIT-6 (from 55 [54-64] to 44 [36-52], p<0.001) scores were significantly improved after BoNT/A therapy. Logistic regression analysis revealed significant interaction between TTH associated with HFS and the presence of stress factors (odds ratio 43.11: 2.95-629.39, p<0.001) and history of chronic headache (odds ratio 28.53: 2.96-275.10, p<0.001). Primary headache, especially TTH, is associated with HFS. BoNT/A therapy for HFS may also be indirectly effective for treatment of TTH. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Antimicrobial Effect and Surface Tension of Some Chelating Solutions with Added Surfactants.

    Science.gov (United States)

    Giardino, Luciano; Andrade, Flaviana Bombarda de; Beltrami, Riccardo

    2016-01-01

    This study assessed the antimicrobial efficacy and surface tension of established irrigating solutions with a new experimental chelating solution in infected dentin tubes. Twenty-five specimens were randomly assigned to each of the irrigating solutions. Twenty specimens were used as negative and positive controls. After 21 days of contamination with E. faecalis, the irrigating solutions MTAD, QMiX and Tetraclean NA were delivered into each infected root canal. The solutions were removed and dentin samples were withdrawn from the root canals with sterile low-speed round burs with increasing ISO diameters. The dentin powder samples obtained with each bur were immediately collected in separate test tubes containing 3 mL of BHI broth. After that, 100 μL from each test tube was cultured on blood agar. The grown colonies were counted and recorded as colony-forming units (CFU). The surface tension of the irrigants was measured using a Cahn DCA-322 Dynamic Contact Angle Analyzer. A Kruskal Wallis nonparametric ANOVA and a Friedman test were used (psurface tension and CFU values than MTAD and QMiX. Better antibacterial action and low surface tension were observed for Tetraclean NA, probably due to the improved penetration into the root canal and dentinal tubes.

  10. Effective Use of Relaxation Training in Dealing with Tension and Anxiety: A Selected Review.

    Science.gov (United States)

    Scherer, Shawn E.; Pass, Larry E.

    1979-01-01

    Relaxation training is employed in relation to systematic desensitization treatment of phobias and as a direct means of dealing with tension and anxiety. Suggests that the greatest benefit may be derived when the procedures are viewed as developing coping skill and are directly related to the individual's daily living situation. (Author)

  11. Effects of non-uniform interfacial tension in small Reynolds number ...

    Indian Academy of Sciences (India)

    Taylor and Acrivos [1] considered the problem of small Reynolds number flow past a spherical liquid drop with uniform interfacial tension between the liquid drop and the sur- rounding fluid. The problem is a singular perturbation problem and Taylor and Acrivos calculated the solution to first order in the Reynolds number.

  12. Oxygen tension affects lubricin expression in chondrocytes.

    Science.gov (United States)

    Hatta, Taku; Kishimoto, Koshi N; Okuno, Hiroshi; Itoi, Eiji

    2014-10-01

    We assessed the effects of oxygen tension on lubricin expression in bovine chondrocytes and cartilage explants and a role for hypoxia-inducible transcription factor (HIF)-1α in regulating lubricin expression was investigated using a murine chondroprogenitor cell line, ATDC5, and bovine chondrocytes isolated from superficial and middle/deep zones of femoral cartilage. ATDC5 cells and bovine chondrocytes were cultured in micromass under different oxygen tensions (21%, 5%, and 1%). ATDC5 cells and middle/deep zone chondrocytes that initially had low lubricin expression levels were also cultured with or without transforming growth factor (TGF)-β1. Quantitative reverse transcription (RT)-PCR was used to determine lubricin and chondrogenic marker gene mRNA levels and immunohistochemistry was used to assess lubricin protein expression. Explant cartilage plugs cultured under different oxygen tensions were also subjected to immunohistological analysis for lubricin. HIF-1α gene silencing was achieved by electroporatic transfer into ATDC5 cells. A low oxygen tension reduced lubricin gene expression levels in bovine superficial chondrocytes, TGF-β1-treated middle/deep zone chondrocytes, and TGF-β1-treated ATDC5 cells. Lubricin expression in explant cartilage was also suppressed under hypoxia. HIF-1α gene silencing in ATDC5 cells attenuated the lubricin expression response to the oxygen tension. These results corroborate with previous studies that the oxygen tension regulates lubricin gene expression and suggest that HIF-1α plays an important role in this regulation. The normal distribution of lubricin in articular cartilage may be due to the hypoxic oxygen environment of cartilage as it is an avascular tissue. An oxygen tension gradient may be a key factor for engineering cartilage tissue with a layered morphology.

  13. The effect of surface tension of dispersion medium on the process of emulsion cooligomerization of ?9 fraction

    OpenAIRE

    Fuch, Ulyana; Subtelnyy, Roman; Guminilovych, Liliya; Maresh, Zoryana

    2013-01-01

    This publication presents the results of research of emulsion cooligomerization of mixture of unsaturated hydrocarbons of C9 fraction from liquid products after diesel pyrolysis. This mixture of hydrocarbons is a by-product of the olefins production. This is one of the possible options to reduce the process temperature and duration of reaction, and hence energy consumption. The effect of surface tension on the process was investigated. The dependence of then concentration of emulsifier E-30 o...

  14. Effects of a Novel Neurodynamic Tension Technique on Muscle Extensibility and Stretch Tolerance: A Counterbalanced Cross-Over Study.

    Science.gov (United States)

    Pietrzak, M; Vollaard, N B J

    2016-12-19

    Neurodynamic tension affects hamstring extensibility and stretch tolerance, and is considered important in hamstring injury management. Neurodynamic tension was postulated to affect segmental muscle extensibility and stretch tolerance, and potentially also demonstrate extra-segmental and contralateral effects. Assess the effects of a novel sciatic-tibial neurodynamic tension technique, the modified long sit slump (MLSS), on segmental, extra-segmental and contralateral muscle extensibility and stretch tolerance. Counterbalanced cross-over study. University research laboratory. Thirteen healthy and active subjects (mean ± SD age 24 ± 8y, BMI 23.1 ± 2.8 kg·m-2). MLSS application (5 seconds, 5 repetitions, 3 sets) on two occasions with a three-week washout period,and either stance or skill leg treated in a counterbalanced manner. Segmental and extra-segmental muscle extensibility were measured utilising passive straight leg raise (PSLR) and prone knee bend (PKB) at pre-, immediately post- and one hour post-intervention. Stretch intensity ratings were measured utilising a simple numerical rating scale (SNRS). MLSS significantly increased PSLR and PKB bilaterally (p < 0.001). The effect for PSLR was greater in the ipsilateral leg compared to the contralateral leg (baseline to one hour post: +9 ± 6° and +5 ± 5° respectively, p < 0.001), but not for PKB (baseline to one hour post: ipsilateral leg +5 ± 5°, contralateral leg +5 ± 4°). For both PSLR and PKB the effect of the first session was retained at the start of the second session 3 weeks later. SNRS data were consistent with increased stretch tolerance. Application of a novel sciatic-tibial neurodynamic tension technique, the MLSS, increases muscle extensibility and stretch tolerance segmentally, extra-segmentally and contra-laterally.

  15. Effective interfacial tension effect on the instability of streaming Rivlin-Ericksen elastico-viscous fluid flow through a porous medium

    Science.gov (United States)

    Singh, M.

    2016-02-01

    The instability of the plane interface between two uniform, superposed and streaming Rivlin-Ericksen elastico-viscous fluids through porous media, including the `effective interfacial tension' effect, is considered. In the absence of the `effective interfacial tension' stability/instability of the system as well as perturbations transverse to the direction of streaming are found to be unaffected by the presence of streaming if perturbations in the direction of streaming are ignored, whereas for perturbation in all other directions, there exists instability for a certain wave number range. The `effective interfacial tension' is able to suppress this Kelvin-Helmholtz instability for small wavelength perturbations, the medium porosity reduces the stability range given in terms of a difference in streaming velocities.

  16. Natural convection with evaporation in a vertical cylindrical cavity under the effect of temperature-dependent surface tension

    Science.gov (United States)

    Kozhevnikov, Danil A.; Sheremet, Mikhail A.

    2018-01-01

    The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number.

  17. Natural convection with evaporation in a vertical cylindrical cavity under the effect of temperature-dependent surface tension

    Science.gov (United States)

    Kozhevnikov, Danil A.; Sheremet, Mikhail A.

    2017-07-01

    The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number.

  18. Pullout reattachment of tibial avulsion fractures of the anterior cruciate ligament: a firm, effective suture-tying method using a tensioner.

    Science.gov (United States)

    Kim, Young-Mo; Kim, Sung-Jae; Yang, Jun-Young; Kim, Kyung-Cheon

    2007-07-01

    We describe a firm, effective suture-tying method using a tensioner for reattaching tibial avulsion fractures of the anterior cruciate ligament. Our simple method achieves strong, firm reattachment of the fracture. In addition, it prevents fixation loosening during suture tying effectively. Since pullout repair using nonabsorbable sutures is commonly used to fix various avulsion fractures, the tensioner helps attain strong, firm reattachment of avulsion fractures simply and effectively.

  19. The in vitro Effect of Irrigants with Low Surface Tension on Enterococcus faecalis.

    Science.gov (United States)

    Giardino, Luciano; Estrela, Carlos; Generali, Luigi; Mohammadi, Zahed; Asgary, Saeed

    2015-01-01

    Due to the complex anatomy of the root canal system and high surface tension of common root canal irrigants (RCI), conducting an investigation on RCIs containing surfactants is a priority. The aim of this in vitro study was to verify the antibacterial potential of RCI with low surface tension in root canals infected with Enterococcus faecalis (E. faecalis). Thirty-five extracted human maxillary anterior teeth were prepared and inoculated with E. faecalis for 60 days. After root canal preparation, the teeth were randomly divided to one positive and one negative control groups and 5 experimental groups: Hypoclean/Tetraclean NA, Hypoclean, Tetraclean, NaOCl/Tetraclean and NaOCl. Bacterial growth was observed by turbidity of culture medium and then measured using a UV spectrophotometer. Data were analyzed in three time intervals (pre-instrumentation and, 20 min and 72 h after canal preparation) using the ANOVA and post hoc Tukey's tests. The level of significance was set at 0.05. The results indicated the presence of E. faecalis in all post-irrigation samples irrespective of the RCI. However, the optical densities in both post-irrigation periods showed bacterial reduction and significant differences between groups. RCI with low surface tension showed antibacterial potential in E. faecalis infected roots.

  20. The effects of alcohol on mood induced by an emotional film. A study among women

    NARCIS (Netherlands)

    van Tilburg, M.A.L.; Vingerhoets, A.J.J.M.

    2002-01-01

    Objective: The present study was designed to investigate the effects of alcohol on women's reactions to a negative mood-inducing stimulus. It is hypothesized that, like in men, alcohol also reduces tension or induces positive mood in women. In addition, we explored whether different mood states were

  1. Multiphase Allen-Cahn and Cahn-Hilliard models and their discretizations with the effect of pairwise surface tensions

    Science.gov (United States)

    Wu, Shuonan; Xu, Jinchao

    2017-08-01

    In this paper, the mathematical properties and numerical discretizations of multiphase models that simulate the phase separation of an N-component mixture are studied. For the general choice of phase variables, the unisolvent property of the coefficient matrix involved in the N-phase models based on the pairwise surface tensions is established. Moreover, the symmetric positive-definite property of the coefficient matrix on an (N - 1)-dimensional hyperplane - which is of fundamental importance to the well-posedness of the models - can be proved equivalent to some physical condition for pairwise surface tensions. The N-phase Allen-Cahn and N-phase Cahn-Hilliard equations can then be derived from the free-energy functional. A natural property is that the resulting dynamics of concentrations are independent of phase variables chosen. Finite element discretizations for N-phase models can be obtained as a natural extension of the existing discretizations for the two-phase model. The discrete energy law of the numerical schemes can be proved and numerically observed under some restrictions pertaining to time step size. Numerical experiments including the spinodal decomposition and the evolution of triple junctions are described in order to investigate the effect of pairwise surface tensions.

  2. Effects of non-woven mesh in preperitoneal tension-free inguinal hernia repair: a retrospective cohort study.

    Science.gov (United States)

    Liu, Yiting; Shen, Yingmo; Chen, Jie

    2017-08-01

    Tension-free hernia repair has been recognized as the gold standard for the treatment of inguinal hernia. Different mesh has different characteristics that influence the efficiency of surgery. We conducted this study to evaluate the effectiveness of non-woven mesh in preperitoneal tension-free inguinal hernia repair under local anesthesia. The medical records of patients who received preperitoneal tension-free inguinal hernia repair under local anesthesia in our hospital from 2012 to 2015 were reviewed. Patients were included if their surgery was conducted using non-woven or woven mesh. Outcome measures were operation time, length of stay in hospital, hospital fees, complications and degree of chronic pain, foreign body sensation and recurrence. A total of 389 cases were included. 186 cases were repaired with non-woven mesh (observation group), and 203 cases were repaired with woven mesh (control group). There were no significant differences in operation time and length of stay in the hospital, but hospital fees were significantly higher in the observation group. Seroma of the inguinal region occurred in 6 cases of the observation group and 8 cases of the control group with no significant difference and no other complications and recurrence in both groups. No cases of chronic pain were recorded in the observation group; 8 cases were recorded in the control group. Foreign body sensation was found in 1 case of the observation group and 9 cases in the control group, which showed attractive advantages of non-woven mesh. Preperitoneal tension-free repair for inguinal hernia under local anesthesia using non-woven or woven mesh is available. The hospital cost of using non-woven mesh is higher than that of woven mesh, but the incidence rate of chronic pain and foreign body sensation are lower in the use of non-woven mesh. Therefore, non-woven mesh may be worth using in the clinical setting.

  3. Social and environmental tensions

    DEFF Research Database (Denmark)

    Saito, Moeko; Rutt, Rebecca Leigh; Chhetri, Bir Bahadur Khanal

    2014-01-01

    to forests. Our case highlights the risk that the mere application of affirmative measures may give rise to difficult social and environmental tensions. Thus, this paper calls for such measures to effectively incorporate local perspectives in their designs and to be reflective, by allowing for regular...

  4. A displacement-based approach for determining non-linear effects on pre-tensioned-cable cross-braced structures

    Science.gov (United States)

    Giaccu, Gian Felice; Caracoglia, Luca

    2017-04-01

    Pre-tensioned-cable bracing systems are widely employed in structural engineering to limit lateral deflections and stabilize structures. A suitable configuration of the pre-tensioned-cable bracing systems in a structure is an important issue since the internal force distribution, emerging from the interaction with the existing structure, significantly affects the structural dynamic behavior. The design, however, is often based on the intuition and the previous experience of the engineer. In recent years, the authors have been investigating the non-linear dynamic response of cable systems, installed on cable-stayed bridges, and in particular the so-called ;cable-cross-tie systems; forming a cable network. The bracing cables (cross-ties) can exhibit slackening or snapping. Therefore, a non-linear unilateral model, combined with the taut-cable theory, is required to simulate the incipient slackening conditions in the stays. Capitalizing from this work on non-linear cable dynamics, this paper proposes a new approach to analyze, in laterally- braced truss structures, the unilateral effects and dynamic response accounting for the loss in the pre-tensioning force imparted to the bracing cables. This effect leads to non-linear vibration of the structure. In this preliminary study, the free vibrations of the structure are investigated by using the ;Equivalent Linearization Method;. A performance coefficient, a real positive number between 0.5 and 1.0, is defined and employed to monitor the relative reduction in the apparent stiffness of the braces during structural vibration, ;mode by mode;. It is shown that the system can exhibit alternate unilateral behavior of the cross-braces. A reduction of the performance coefficient close to fifty percent is observed in the braces when the initial pre-tensioning force is small. On the other hand the performance coefficient tends to one in the case of a high level of pre-stress. It is concluded that the performance coefficient may

  5. Effects of Added Salts on Surface Tension and Aggregation of Crown Ether Surfactants.

    Science.gov (United States)

    Suzuki, Maki; Fujio, Katsuhiko

    2016-01-01

    Two crown ether surfactants, dodecanoyloxymethyl- (C11Φ6) and octanoyloxymethyl-18-crown-6 (C7Φ6), were synthesized and the surface tension dependence on surfactant concentration of their aqueous solutions was measured both in the absence and presence of alkali chlorides to confirm the critical micelle concentration (CMC) is highest for the added cation that have an ionic diameter comparable to the hole size of the crown ether ring and that several break points on the surface tension vs. concentration curves occur for these crown ether surfactants. For C11Φ6 and C7Φ6, in the absence of salt, the surface tension vs. concentration curves had two break points. Using the solubilization of a water-insoluble dye as an indicator, we found that the break point at the higher concentration (m0) for C7Φ6 was due to micelle formation. Two break points were also observed for the aqueous solution of C11Φ6 in the presence of NaCl, KCl, RbCl, and CsCl salts at concentrations of 0.22 mol kg(-1) and for C7Φ6 with 0.22 mol kg(-1) KCl added. The CMC (m0) was found to be the highest for solutions containing K(+) salts because K(+) has an ionic diameter comparable to the hole size of 18-crown-6 ring. Furthermore, the CMC decreased as the ionic diameters of the added cations deviated from the hole size. The molecular areas at two break points, estimated by the Gibbs adsorption isotherm, except for that at the break point at mI of C7Φ6, were very small for an adsorbed monolayer. Further investigation is required to elucidate the reason for the break point at mI.

  6. EFFECT OF PROPHYLACTIC ANTIBIOTIC ON SURGICAL SITE INFECTION AFTER TENSION-FREE HERNIOPLASTY

    Directory of Open Access Journals (Sweden)

    Y Saskia-Javi

    2013-05-01

    Full Text Available Objective: prophylactic antibiotics were remains applied for hernioplasty treatment at Sanglah General Hospital Bali-Indonesia. On the other hand, there were no comprehensive infection incidence data gathered. This research aims to determine incidence differences of post operative infection inpatients underwent tension-free hernioplasty and received prophylactic antibiotics compared to thosewho received placebo. The general purpose of this research is to determine the necessity of prophylactic antibiotics in the hope of setting new procedural standards in elective hernia procedures thus reducing cost and bacteria resistance.Patients and Method: This was an open label randomizedclinical trial conducted at Sanglah General Hospital Department of General Surgery from October 2011. The target population was all patients who underwent tension-free hernioplasty procedure, in Sanglah General Hospital. The acquired data was analyzed after an independent t test was performed. a Mann-Whitney U test, Fisher’s exact test, and Two-Sample Kolmogorov-Smirnov test were used todetermine the correlations between variables, where p < 0.05 was regardless of significant.Results: From 54 subjects 3 (5.6% of them were found to have a slight erythema around the operation wound,on the 7th,14th,21th, and 28th day no signs of erythema were found. From the three subjects two (7.4% were from the placebo group and one (3.7% from the antibiotic group. All clinical assessment of post operative wound was made using Southampton Wound Assessment Scale, where erythema is a grade 1C, all subjects healed primarily.Conclusion: An Open Label Randomized Clinical Trial comparing SSI in post tension-free hernioplasty patients who were given prophylactic antibiotics and placebo.No significant difference were found.

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

    Science.gov (United States)

    Rolland, A.; Aufray, B.

    1985-10-01

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

  8. Effects of sample storage time, temperature and syringe type on blood gas tensions in samples with high oxygen partial pressures.

    OpenAIRE

    Pretto, J. J.; Rochford, P D

    1994-01-01

    BACKGROUND--Although plastic arterial sampling syringes are now commonly used, the effects of sample storage time and temperature on blood gas tensions are poorly described for samples with a high oxygen partial pressure (PaO2) taken with these high density polypropylene syringes. METHODS--Two ml samples of tonometered whole blood (PaO2 86.7 kPa, PaCO2 4.27 kPa) were placed in glass syringes and in three brands of plastic blood gas syringes. The syringes were placed either at room temperature...

  9. 3D simulations of rising magnetic flux tubes in a compressible rotating interior: The effect of magnetic tension

    Science.gov (United States)

    Fournier, Y.; Arlt, R.; Ziegler, U.; Strassmeier, K. G.

    2017-10-01

    Context. Long-term variability in solar cycles represents a challenging constraint for theoretical models. Mean-field Babcock-Leighton dynamos that consider non-instantaneous rising flux tubes have been shown to exhibit long-term variability in their magnetic cycle. However a relation that parameterizes the rise-time of non-axisymmetric magnetic flux tubes in terms of stellar parameters is still missing. Aims: We aim to find a general parameterization of the rise-time of magnetic flux tubes for solar-like stars. Methods: By considering the influence of magnetic tension on the rise of non-axisymmetric flux tubes, we predict the existence of a control parameter referred as Γα1α2. This parameter is a measure of the balance between rotational effects and magnetic effects (buoyancy and tension) acting on the magnetic flux tube. We carry out two series of numerical experiments (one for axisymmetric rise and one for non-axisymmetric rise) and demonstrate that Γα1α2 indeed controls the rise-time of magnetic flux tubes. Results: We find that the rise-time follows a power law of Γα1α2 with an exponent that depends on the azimuthal wavenumber of the magnetic flux loop. Conclusions: Compressibility does not impact the rise of magnetic flux tubes, while non-axisymmetry does. In the case of non-axisymmetric rise, the tension force modifies the force balance acting on the magnetic flux tube. We identified the three independent parameters required to predict the rise-time of magnetic flux tubes, that is, the stellar rotation rate, the magnetic flux density of the flux tube, and its azimuthal wavenumber. We combined these into one single relation that is valid for any solar-like star. We suggest using this generalized relation to constrain the rise-time of magnetic flux tubes in Babcock-Leighton dynamo models.

  10. Surface tension of aqueous humor.

    Science.gov (United States)

    Ross, Andrew; Blake, Robert C; Ayyala, Ramesh S

    2010-09-01

    To measure and compare the surface tension of aqueous humor in patients with and without glaucoma. The surface tension of aqueous humor was measured using a commercially available instrument and software that were validated by using a known fluid (deionized water and methanol). Analysis of aqueous and vitreous samples obtained from 20 rabbit eyes showed that the system could be used successfully for small amounts of ocular fluid. The effect of glaucoma drugs on the surface tension of aqueous humor was then studied in a rabbit model. Comparison of aqueous humor from 66 patients with glaucoma and 53 patients with cataracts but no glaucoma was carried out. The surface tension of rabbit aqueous humor was 65.9 ± 1.2; vitreous, 60.6 ± 2.6; and balanced salt solution, 70.7 ± 0.9. Timolol and latanoprost did not alter the surface tension of the aqueous humor in the rabbit model. The average surface tension of human aqueous humor was 63.33 ± 4.0 (glaucomatous eyes) and 66.19 ± 2.64 (nonglaucomatous eyes with cataracts) (P=0.0001). A technique of measuring the surface tension from small quantities of aqueous humor is validated. Surface tension of the aqueous humor in glaucoma patients was less than that of cataract patients.

  11. Reduction in wire tension caused by wire clamping and wire tensioner removal: an experimental Ilizarov frame study.

    Science.gov (United States)

    La Russa, Valentina; Skallerud, Bjørn; Klaksvik, Jomar; Foss, Olav A

    2011-03-01

    The stability of an external ring fixator mainly depends on wire tension. Wire fixators should maintain the tension during both wire clamping to the ring and removal of the tensioner device. In the present study the loss in wire tension related to fixator clamping and wire tensioner removal using three different wire fixator designs was studied. The fixators were based on two different cannulated bolts and a washer. Effects from two different pretension levels in combination with three different bolt torque levels upon loss in wire tension were described. Emitted wire vibration frequency was used to assess the corresponding wire tension. Wire tension was determined after each wire fixator tightening and after the removal of the wire tensioner. Increased bolt torque led to a small decrease in tension for both pretension levels. A considerable higher tension loss was measured when removing the wire tensioner. In all cases, the combination of a new cannulated bolt and a washer maintained the highest tension.

  12. Effect of manual therapy techniques on headache disability in patients with tension-type headache. Randomized controlled trial.

    Science.gov (United States)

    Espí-López, G V; Rodríguez-Blanco, C; Oliva-Pascual-Vaca, A; Benítez-Martínez, J C; Lluch, E; Falla, D

    2014-12-01

    Tension-type headache (TTH) is the most common type of primary headache however there is no clear evidence as to which specific treatment is most effective or whether combined treatment is more effective than individual treatments. To assess the effectiveness of manual therapy techniques, applied to the suboccipital region, on aspects of disability in a sample of patients with tension-type headache. Randomized Controlled Trial. Specialized centre for headache treatment. Seventy-six (62 women) patients (age: 39.9 ± 10.9 years) with episodic chronic TTH. Patients were randomly divided into four treatment groups: 1) suboccipital soft tissue inhibition; 2) occiput-atlas-axis manipulation; 3) combined treatment of both techniques; 4) control. Four sessions were applied over 4 weeks and disability was assessed before and after treatment using the Headache Disability Inventory (HDI). Headache frequency, severity and the functional and emotional subscales of the questionnaire were assessed. Photophobia, phonophobia and pericranial tenderness were also monitored. Headache frequency was significantly reduced with the manipulative and combined treatment (Pmanual therapy treatments showed a positive change in headache features, measures of photophobia, photophobia and pericranial tenderness only improved in the group that received the combined treatment suggesting that combined treatment is the most appropriate for symptomatic relief of TTH.

  13. Effect of tension and curvature on the chemical potential of lipids in lipid aggregates.

    Science.gov (United States)

    Grafmüller, Andrea; Lipowsky, Reinhard; Knecht, Volker

    2013-01-21

    Understanding the factors that influence the free energy of lipids in bilayer membranes is an essential step toward understanding exchange processes of lipids between membranes. In general, both lipid composition and membrane geometry can affect lipid exchange rates between bilayer membranes. Here, the free energy change ΔG(des) for the desorption of dipalmitoyl-phosphatidylcholine (DPPC) lipids from different lipid aggregates has been computed using molecular dynamics simulations and umbrella sampling. The value of ΔG(des) is found to depend strongly on the local properties of the aggregate, in that both tension and curvature lead to an increase in ΔG(des). A detailed analysis shows that the increased desorption free energy for tense bilayers arises from the increased conformational entropy of the lipid tails, which reduces the favorable component -TΔS(L) of the desorption free energy.

  14. Theory and computer simulation of solute effects on the surface tension of liquids.

    Science.gov (United States)

    Chen, Feng; Smith, Paul E

    2008-07-31

    A complete description of the thermodynamics of planar mixed solute-solvent interfaces suitable for the analysis of computer simulation data is provided. The approach uses surface probability distributions to characterize the interface regions, coupled with radial distribution functions and the Kirkwood-Buff theory of solutions to characterize the bulk solution properties. The approach is then used to understand the relationship between changes in the surface tension, the degree of surface adsorption or depletion, and the bulk solution properties of two aqueous solute systems. The first, aqueous NaCl solutions, provides an example of a surface excluded solute. The second, aqueous methanol solutions, provides an example of a surface adsorbed solute. The numerical results support the theoretical relationships described here and provide a consistent picture of the thermodynamics of solution interfaces involving any number of components which can be applied to a wide variety of systems.

  15. Effects of contact line hysteresis and surface tension on contact line pinning of inclined droplets.

    Science.gov (United States)

    Berejnov, Viatcheslav; Thorne, Robert E.

    2006-03-01

    The stability and pinning of drops on inclined surfaces is of fundamental and technological interest. Contact line dynamics depends on the properties of the liquid, the solid surface and the manner in which line motion is driven. Achieving reproducible final contact line and drop shapes is important in biotechnology applications where drops are used as mini-reactors, such as in structural genomics where sessile drops are used for protein and virus crystallization. We will describe experiments investigating pinning and deformation of drops containing pure liquids, proteins and colloids, placed on substrates with a range of surface treatments. Proteins affect contact angle hysteresis at low concentrations, and surface tension at high concentration, leading to two different regimes of pinning. Theoretical approaches that can be useful in understanding our results will also be presented.

  16. Effect of crack curvature on stress intensity factors for ASTM standard compact tension specimens

    Science.gov (United States)

    Alam, J.; Mendelson, A.

    1983-01-01

    The stress intensity factors (SIF) are calculated using the method of lines for the compact tension specimen in tensile and shear loading for curved crack fronts. For the purely elastic case, it was found that as the crack front curvature increases, the SIF value at the center of the specimen decreases while increasing at the surface. For the higher values of crack front curvatures, the maximum value of the SIF occurs at an interior point located adjacent to the surface. A thickness average SIF was computed for parabolically applied shear loading. These results were used to assess the requirements of ASTM standards E399-71 and E399-81 on the shape of crack fronts. The SIF is assumed to reflect the average stress environment near the crack edge.

  17. Effects of mindfulness-based stress reduction on perceived stress and psychological health in patients with tension headache.

    Science.gov (United States)

    Omidi, Abdollah; Zargar, Fatemeh

    2015-11-01

    Programs for improving health status of patients with illness related to pain, such as headache, are often still in their infancy. Mindfulness-based stress reduction (MBSR) is a new psychotherapy that appears to be effective in treating chronic pain and stress. This study evaluated efficacy of MBSR in treatment of perceived stress and mental health of client who has tension headache. This study is a randomized clinical trial. Sixty patients with tension type headache according to the International Headache Classification Subcommittee were randomly assigned to the Treatment As Usual (TAU) group or experimental group (MBSR). The MBSR group received eight weekly classmates with 12-min sessions. The sessions were based on MBSR protocol. The Brief Symptom Inventory (BSI) and Perceived Stress Scale (PSS) were administered in the pre- and posttreatment period and at 3 months follow-up for both the groups. The mean of total score of the BSI (global severity index; GSI) in MBSR group was 1.63 ± 0.56 before the intervention that was significantly reduced to 0.73 ± 0.46 and 0.93 ± 0.34 after the intervention and at the follow-up sessions, respectively (P stress in comparison with the control group at posttest evaluation. The mean of perceived stress before the intervention was 16.96 ± 2.53 and was changed to 12.7 ± 2.69 and 13.5 ± 2.33 after the intervention and at the follow-up sessions, respectively (P stress in the TAU group at pretest was 15.9 ± 2.86 and that was changed to 16.13 ± 2.44 and 15.76 ± 2.22 at posttest and follow-up, respectively (P stress and improve general mental health in patients with tension headache.

  18. Butler-Sugimoto monomolecular bilayer interface model: the effect of oxygen on the surface tension of a liquid metal and its wetting of a ceramic.

    Science.gov (United States)

    Yen, Pei-Shan; Datta, Ravindra

    2014-07-15

    The influence of oxygen on liquid-gas surface tension of molten metals has been well-investigated experimentally and modeled theoretically via the Szyszkowski equation, derivable from the Butler molecular monolayer interface model. However, there is no corresponding model describing the experimentally observed profound effect of oxygen partial pressure on solid-liquid surface tension as well as on contact angle of molten metals on ceramic substrates. Here, we utilize the Butler-Sugimoto thermodynamic approach based on a monomolecular bilayer interface model to investigate the effect of oxygen partial pressure on liquid-gas as well as solid-liquid surface tension of molten Cu/Al2O3 and molten Ag/Al2O3 systems. It is shown that both liquid-gas and solid-liquid surface tension are a strong function of oxygen activity in the melt, which, in turn, depends on gas-phase oxygen partial pressure, in conformity with experiments. The change in solid-liquid surface tension and wetting is also greatly affected by the change in liquid-gas surface tension. This improved understanding is of practical significance in many applications. Copyright © 2014. Published by Elsevier Inc.

  19. An ecological approach to learning with technology: responding to tensions within the "wow-effect" phenomenon in teaching practices

    Science.gov (United States)

    Herro, Danielle

    2016-12-01

    This review explores Anne Kamstrupp's "The Wow-effect in Science Teacher Education" by examining her theorized "wow-effect" as a teaching enactment that may serve to engage students, but often fails to provide deep understanding of science content. My response extends her perspective of socio-materiality as means to understand the "wow-effect" by suggesting social constructivism provides a more accurate lens to disentangle the phenomenon. I react to her position that tension fields within the phenomenon include the relationship between new and old technologies, boredom and engagement, and active and sedentary learning. In this conversation, I point to a new way of conceptualizing using digital media in the classroom as ecology of learning that may serve to decrease problems associated with the "wow-effect".

  20. Effects of sodium substitutes on transient inward current and tension in guinea-pig and ferret papillary muscle.

    Science.gov (United States)

    Arlock, P; Katzung, B G

    1985-03-01

    We used ouabain-treated guinea-pig and ferret papillary muscles to study transient inward current (Iti), after-contractions, and tonic tension development during voltage-clamp pulses. Li, sucrose and choline were used isosmotically as Na substitutes to evaluate the effect of altering the Na equilibrium potential. We were unable to detect outward Iti at any potential up to +30 mV in normal or Na-depleted solutions. However, reduction of Na had a biphasic effect on Iti, initially increasing it and then reducing it at all clamp potentials from -50 to +20 mV. After-contractions were also initially increased and, in sufficiently Na-depleted solutions, decreased by reduction of extracellular Na. However, the peak in the after-contraction always occurred later than the increase in Iti and frequently coincided with the maximum suppression of the current. Complete suppression of after-contractions was not often achieved and always required more complete Na replacement than Iti suppression. Tonic tension responses were reduced by Na replacement, usually in synchrony with the reduction of Iti. The responses of Iti to Na replacement are consistent with a model of electrogenic Na-Ca exchange over the potential range positive to -50 mV. The responses deviate from the predictions of the model at more negative potentials. The results are consistent with the previous proposal that oscillatory changes in internal free Ca concentration underlie both Iti and after-contractions.

  1. Effectiveness of a Treatment Involving Soft Tissue Techniques and/or Neural Mobilization Techniques in the Management of Tension-Type Headache: A Randomized Controlled Trial.

    Science.gov (United States)

    Ferragut-Garcías, Alejandro; Plaza-Manzano, Gustavo; Rodríguez-Blanco, Cleofás; Velasco-Roldán, Olga; Pecos-Martín, Daniel; Oliva-Pascual-Vaca, Jesús; Llabrés-Bennasar, Bartomeu; Oliva-Pascual-Vaca, Ángel

    2017-02-01

    To evaluate the effects of a protocol involving soft tissue techniques and/or neural mobilization techniques in the management of patients with frequent episodic tension-type headache (FETTH) and those with chronic tension-type headache (CTTH). Randomized, double-blind, placebo-controlled before and after trial. Rehabilitation area of the local hospital and a private physiotherapy center. Patients (N=97; 78 women, 19 men) diagnosed with FETTH or CTTH were randomly assigned to groups A, B, C, or D. (A) Placebo superficial massage; (B) soft tissue techniques; (C) neural mobilization techniques; (D) a combination of soft tissue and neural mobilization techniques. The pressure pain threshold (PPT) in the temporal muscles (points 1 and 2) and supraorbital region (point 3), the frequency and maximal intensity of pain crisis, and the score in the Headache Impact Test-6 (HIT-6) were evaluated. All variables were assessed before the intervention, at the end of the intervention, and 15 and 30 days after the intervention. Groups B, C, and D had an increase in PPT and a reduction in frequency, maximal intensity, and HIT-6 values in all time points after the intervention as compared with baseline and group A (P<.001 for all cases). Group D had the highest PPT values and the lowest frequency and HIT-6 values after the intervention. The application of soft tissue and neural mobilization techniques to patients with FETTH or CTTH induces significant changes in PPT, the characteristics of pain crisis, and its effect on activities of daily living as compared with the application of these techniques as isolated interventions. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  2. Noradrenaline-induced increases in calcium and tension in skeletal muscle conductance and resistance arteries from rats with post-infarction heart failure

    DEFF Research Database (Denmark)

    Trautner, Simon; Amtorp, Ole; Boesgaard, Soren

    2006-01-01

    We tested the hypothesis that arterial reactivity to noradrenaline is augmented in congestive heart failure (CHF), which could contribute to the deleterious changes in peripheral vascular resistance and compliance in this condition. From male Wistar rats with post-infarction CHF and sham-operated......We tested the hypothesis that arterial reactivity to noradrenaline is augmented in congestive heart failure (CHF), which could contribute to the deleterious changes in peripheral vascular resistance and compliance in this condition. From male Wistar rats with post-infarction CHF and sham......-operated rats, skeletal muscle conductance and resistance arteries (mean lumen diameters: 514 and 186 microm) were isolated and mounted on wire myographs, and wall tension was recorded in response to cumulative application of acetylcholine and noradrenaline to the vessel segments. In a subset of experiments....... In the resistance arteries of CHF rats, the noradrenaline-induced increases in [Ca(2+)](i) were significantly enhanced (P=0.003). Despite the augmented [Ca(2+)](i) levels, the tension responses to noradrenaline were unaltered in these arteries. In the conductance arteries, there were no significant differences...

  3. Effects of tension on specific conductivity and vulnerability to embolism of Quercus ilex seedlings grown at two atmospheric CO{sub 2} concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Gartner, B. L.; Roy, J. [Centre National de la Recherce Scientifique, Centre d' Ecologie Functionelle et Evolutive, Montpellier (France); Huc, R. [Institut National de la Recherche Agronomique, Avignon (France)

    2003-04-01

    Decreases in the hydraulic function of a woody stem with increased mechanical loading were measured using oak seedlings grown upright or inclined to force the production of large amounts of tension wood. The seedlings were grown in ambient or elevated carbon dioxide concentrations for 16-17 months to provide two sets of seedlings differing in growth rates and allocation patterns. Results in both carbon dioxide environments showed that inclination caused the formation of large amounts of tension wood at the base and mid-sections of most stems, although not at the stem tips. No significant effects of stem inclination or amount of tension wood on specific conductivity or vulnerability to embolism were observed. Vessel frequency, average vessel lumen area, vessel lumen functions, frequency of vessels in the smallest diameter class, and wood density were similar in samples with high tension wood to those found in samples with very little tension wood. The same characteristics were observed in samples grown in elevated carbon dioxide concentration and samples grown in ambient carbon dioxide concentration. Position of the seedlings was significant: wood density was highest and specific conductivity was lowest at the stem base, intermediate at the middle, while density was lowest and specific conductivity highest at the stem tip. These results led to the conclusion that in a species that uses different cells for mechanical support and water transport, tension wood formation may not impact on water transport functions or vulnerability to embolism. 47 refs., 3 tabs., 3 figs.

  4. Molecular-Level Insight of the Effect of Hofmeister Anions on the Interfacial Surface Tension of a Model Protein.

    Science.gov (United States)

    Willow, Soohaeng Yoo; Xantheas, Sotiris S

    2017-04-06

    The effect of the Hofmeister anions on the precipitation of proteins is often discussed using liquid-vapor coexisting systems with the assumption that the liquid-vapor interface mimics the liquid-protein interface. Solvated proteins, however, have both hydrophobic and hydrophilic regions on their surfaces rather than just a pure hydrophobic one. Using a solvated parallel β-sheet layer consisting of both hydrophobic and positively charged hydrophilic surfaces, we investigated the adsorption of kosmotropic (SO 4 2- ) and chaotropic (ClO 4 - ) anions toward the protein's hydrophobic and hydrophilic surfaces via Born-Oppenheimer molecular dynamics simulations using the BLYP density functional theory. It was found that both anions prefer to reside on the hydrophilic surface. Furthermore, kosmotropic anions, like SO 4 2- , enhance the interfacial surface tension of the protein and stabilize the protein, whereas, in contrast, chaotropic anions, like ClO 4 - , weaken the interfacial surface tension of the protein and allow water molecules to penetrate toward the peptide bonds to form water-peptide hydrogen bonds, thus destabilizing the protein.

  5. The Effect of Additional Mooring Chains on the Motion Performance of a Floating Wind Turbine with a Tension Leg Platform

    Directory of Open Access Journals (Sweden)

    Jinping Ou

    2012-04-01

    Full Text Available In this study, two types of floating offshore wind turbine (FOWT systems were proposed: a traditional tension leg platform (TLP type and a new TLP type with additional mooring chains. They were both based on the National Renewable Energy Laboratory 5 MW offshore wind turbine model. Taking the coupled effect of dynamic response of the top wind turbine, tower support structure and lower mooring system into consideration, not only were the 1/60 scale model tests for the two floating wind turbine systems done in HIT’s wind-wave tunnel according to the typical design conditions in IEC61400-3 code, but also the numerical simulations corresponding to the scaled model tests were performed by advanced numerical tools. As a result, the numerical results displayed good agreement with the test data. Moreover, the additional mooring chains could play an active role in reducing the surge displacement, surge acceleration and typical tension leg force responses of the FOWT system, which is very beneficial for ensuring the good operational performance and the safety of the FOWT system.

  6. Travoprost with sofZia® preservative system lowered intraocular pressure of Japanese normal tension glaucoma with minimal side effects

    Directory of Open Access Journals (Sweden)

    Mizoue S

    2014-02-01

    Full Text Available Shiro Mizoue,1 Tadashi Nakano,2 Nobuo Fuse,3 Aiko Iwase,4 Shun Matsumoto,5 Keiji Yoshikawa6 On behalf of the IOP CHANGE Study Group7 1Department of Ophthalmology, Ehime University Graduate School of Medicine, Ehime, Japan; 2Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; 3Department of Integrative Genomics, Tohoku Medical Megabank Organization, Miyagi, Japan; 4Tajimi Iwase Eye Clinic, Gifu, Japan; 5Department of Ophthalmology, Tokyo Teishin Hospital, 6Yoshikawa Eye Clinic, Tokyo, Japan; 7IOP CHecked and Assessed in Normal tension Glaucoma by Exceptional Glaucomatologists Study Group, Japan Background: This study aimed to evaluate the effect of travoprost with sofZia® preservative system for lowering the intraocular pressure (IOP of Japanese normal tension glaucoma (NTG patients. Methods: In this prospective, multicenter, open-label study, Japanese NTG patients with baseline IOPs <20 mmHg were enrolled after three consecutive time measurements taken at screening and baseline visits. Travoprost with sofZia® was instilled once daily. Lowering effect on IOP, conjunctival hyperemia, superficial punctate keratopathy, and adverse events were examined at week 4, 8, and 12 after drug instillation. Results: One-hundred and three of the 107 enrolled patients (baseline IOP =15.2±2.0 mmHg [mean ± standard deviation] completed the study. The mean IOP value as well as percent reduction was significantly reduced at each visit after travoprost with sofZia® initiation (P<0.0001. The conjunctival hyperemia score was 1 or less throughout the study, though it increased significantly over time. No significant change was observed in superficial punctate keratopathy. The cumulative incidence of side effects such as eyelash changes, eyelid pigmentation, and deepening of the upper lid was 47.6%, 27.2%, and 16.5%, respectively. Conclusion: Travoprost preserved with sofZia® effectively lowered the IOP of Japanese NTG patients. It was

  7. STUDY THE EFFECTS OF PRESTRAINS IN UNIAXIAL TENSION ON THE FORMING LIMIT DIAGRAM OF ALUMINUM ALLOY SHEETS(2024 T3

    Directory of Open Access Journals (Sweden)

    Waleed J. Ali

    2013-05-01

    Full Text Available           The strain path for sheet metal may be changed during forming , this may be affect the forming limit curve (FLC . In this work the FLC before and after prestraining was determined for aluminum alloy (2024 T3 to study the effect of this type of prestraining and in different values on the FLC. This alloy was chosen because it is used widely , specially in aircraft structures .It was shown that the using of uniaxial tension prestrain affects the FLC . The major strain in right side is increased with the increasing in the prestrain , while in the left side the effect is small .  

  8. Elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity existing in orthotropic media under uniform tension at infinity

    Science.gov (United States)

    Guo, Lei; Nie, Guohua

    2008-02-01

    This paper presents an analytical solution for the elastic fields induced by non-elastic eigenstrains in a plane elliptical inhomogeneity embedded in the orthotropic matrix under tension at infinity and inclined at any angle. The conformal transformation and complex function method for the anisotropic elastic material were used to determine the strain energies in the inhomogeneity and matrix, which were expressed by four undetermined coefficients characterizing the equilibrium boundary of the inhomogeneity due to the acting eigenstrains and external load. The use of the principle of the minimum potential energy led to analytical expressions for these coefficients and thus generated a closed-form solution for the elastic strain/stress fields. The resulting stress field in the inhomogeneity was examined and verified by checking the continuity conditions for the normal and shear stresses on the interior boundary of the matrix.

  9. Tension-Enhanced Hydrogen Evolution Reaction on Vanadium Disulfide Monolayer

    Science.gov (United States)

    Pan, Hui

    2016-02-01

    Water electrolysis is an efficient way for hydrogen production. Finding efficient, cheap, and eco-friendly electrocatalysts is essential to the development of this technology. In the work, we present a first-principles study on the effects of tension on the hydrogen evolution reaction of a novel electrocatalyst, vanadium disulfide (VS2) monolayer. Two electrocatalytic processes, individual and collective processes, are investigated. We show that the catalytic ability of VS2 monolayer at higher hydrogen coverage can be efficiently improved by escalating tension. We find that the individual process is easier to occur in a wide range of hydrogen coverage and the collective process is possible at a certain hydrogen coverage under the same tension. The best hydrogen evolution reaction with near-zero Gibbs free energy can be achieved by tuning tension. We further show that the change of catalytic activity with tension and hydrogen coverage is induced by the change of free carrier density around the Fermi level, that is, higher carrier density, better catalytic performance. It is expected that tension can be a simple way to improve the catalytic activity, leading to the design of novel electrocatalysts for efficient hydrogen production from water electrolysis.

  10. The immediate effects of tension of counterforce forearm brace on neuromuscular performance of wrist extensor muscles in subjects with lateral humeral epicondylosis.

    Science.gov (United States)

    Ng, G Y F; Chan, H L

    2004-02-01

    Within-subject repeated-measures study. To examine the immediate effects of counterforce forearm brace on isokinetic strenght stretch reflex, passive stretching pain threshold of the wrist extensors, and proprioception of the wrist in subjects with lateral humeral epicondylosis for different strap tensions of a forearm brace. Counterforce forearm bracing has been used for treating lateral humeral epicondylosis, but the effect of brace tension has not been well reported. Fifteen subjects diagnosed with lateral humeral epicondylosis on their dominant arm were tested under 4 randomized conditions: (1) no brace, (2) brace with minimal tension, (3) brace with 25-N tension, and (4) brace with 50-N tension. The tests included isokinetic wrist extensors strength, passive stretching force in wrist flexion to elicit pain in the wrist extensors, wrist proprioception, and stretch reflex latency of the extensor carpi ulnari. A repeated-measures MANOVA was used to analyze the data and significant results were further analyzed with post hoc linear contrasts (alpha = .05). Among the 4 conditions, significant differences were found in wrist proprioception P = .032) and pain threshold to passive stretching of the wrist extensors (P = .05), but were not found in wrist extension isokinetic strength and stretch reflex latency of the extensor carpi ulnaris. A forearm counterforce brace, as applied in this study, affects wrist joint proprioception and increases the pain threshold to passive stretching of the wrist extensors in subjects with lateral humeral epicondylosis, but it has no effect on wrist extensor strength and stretch reflex latency of the extensor carpi ulnaris.

  11. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  12. Determining and Optimizing Effective Factors in Laser Irradiation on Skin Tensional Strength using a Hybrid DOE and DEA Approach

    Directory of Open Access Journals (Sweden)

    Mehdi Bashiri

    2010-03-01

    Full Text Available Introduction: We investigated the characteristic of a suitable irradiation on skin's tensional strength using design of experiments (DOE. The experiments in this research are designed in two phases and data envelopment analysis (DEA is used for performance measurement of each phase. Material and Methods: Samples were provided from pleura as surface tissue made of collagen and elastin fibers. In each experiment, the sample was stretched before and after irradiation. Variation of the sample length was measured. Then force-length data were plotted and the slope of the fitted line was calculated. Variation in these slopes was used as a criterion to determine tissue strength variation after laser irradiation. Furthermore, the output oriented DEA model by variable return to scale was used to examine performance of the designed experiments for each phase. Results: Results of the first phase experiments showed that the main effect of time duration was significant; but this was not the case for beam radius. Regarding polarization, only its interaction effect with time duration was significant. Results of the second phase indicated that laser irradiation with parallel polarization for 10 seconds caused a greater increase in tensional strength. Resultant efficiencies of applying DEA showed that the first phase experiments were more efficient. Discussion and Conclusions: This research has combined DEA and DOE to investigate the effects of laser on skin elasticity. Comparing the results of the two phases indicates that it is more efficient to use the experimental design of phase 1 in our experiment. So for similar future studies, we suggest using more levels for experiments of phase 1 instead of doing the experimental design in two phases.

  13. Effect of Couple Stresses on the Stress Intensity Factors for Two Parallel Cracks in an Infinite Elastic Medium under Tension

    Directory of Open Access Journals (Sweden)

    Shouetsu Itou

    2012-01-01

    Full Text Available Stresses around two parallel cracks of equal length in an infinite elastic medium are evaluated based on the linearized couple-stress theory under uniform tension normal to the cracks. Fourier transformations are used to reduce the boundary conditions with respect to the upper crack to dual integral equations. In order to solve these equations, the differences in the displacements and in the rotation at the upper crack are expanded through a series of functions that are zero valued outside the crack. The unknown coefficients in each series are solved in order to satisfy the boundary conditions inside the crack using the Schmidt method. The stresses are expressed in terms of infinite integrals, and the stress intensity factors can be determined using the characteristics of the integrands for an infinite value of the variable of integration. Numerical calculations are carried out for selected crack configurations, and the effect of the couple stresses on the stress intensity factors is revealed.

  14. Effects of treatment with bimatoprost 0.03% for 3 years in patients with normal-tension glaucoma

    Directory of Open Access Journals (Sweden)

    Inoue K

    2014-06-01

    Full Text Available Kenji Inoue,1 Minako Shiokawa,1 Takayuki Fujimoto,1 Goji Tomita21Inouye Eye Hospital, Tokyo, Japan; 22nd Department of Ophthalmology, Toho University School of Medicine, Tokyo, JapanPurpose: To evaluate the effects of bimatoprost 0.03% single treatment for 3 years on intraocular pressure (IOP and visual field performance.Methods: We monitored the IOP of 62 patients with normal-tension glaucoma every 1–3 months. The Humphrey visual field test was performed every 6 months after treatment and the results obtained were compared to those before treatment. In addition, visual field performance was evaluated using trend and event analysis.Results: The mean ± standard deviation (SD of IOP after treatment with bimatoprost for 3 years (13.6±3.1 mmHg was significantly lower than that before treatment (16.8±2.4 mmHg, P<0.0001. No change was observed in the mean deviation and pattern SD values of the Humphrey visual field before and 3 years after treatment. Worsening of visual field performance was observed in one patient (3.0% by using trend analysis and in four patients (12.1% by using event analysis. Treatment was discontinued in 17 patients (27.4% because of adverse reactions.Conclusion: Bimatoprost 0.03% single treatment was effective in reducing the IOP at least during the 3 years of treatment, but visual field performance worsened by 3.0%–12.1% in patients with normal-tension glaucoma.Keywords: IOP, visual field, trend analysis, event analysis

  15. Effects of mindfulness-based stress reduction on perceived stress and psychological health in patients with tension headache

    Directory of Open Access Journals (Sweden)

    Abdollah Omidi

    2015-01-01

    Full Text Available Background: Programs for improving health status of patients with illness related to pain, such as headache, are often still in their infancy. Mindfulness-based stress reduction (MBSR is a new psychotherapy that appears to be effective in treating chronic pain and stress. This study evaluated efficacy of MBSR in treatment of perceived stress and mental health of client who has tension headache. Materials and Methods: This study is a randomized clinical trial. Sixty patients with tension type headache according to the International Headache Classification Subcommittee were randomly assigned to the Treatment As Usual (TAU group or experimental group (MBSR. The MBSR group received eight weekly classmates with 12-min sessions. The sessions were based on MBSR protocol. The Brief Symptom Inventory (BSI and Perceived Stress Scale (PSS were administered in the pre- and posttreatment period and at 3 months follow-up for both the groups. Results: The mean of total score of the BSI (global severity index; GSI in MBSR group was 1.63 ± 0.56 before the intervention that was significantly reduced to 0.73 ± 0.46 and 0.93 ± 0.34 after the intervention and at the follow-up sessions, respectively (P < 0.001. In addition, the MBSR group showed lower scores in perceived stress in comparison with the control group at posttest evaluation. The mean of perceived stress before the intervention was 16.96 ± 2.53 and was changed to 12.7 ± 2.69 and 13.5 ± 2.33 after the intervention and at the follow-up sessions, respectively (P < 0.001. On the other hand, the mean of GSI in the TAU group was 1.77 ± 0.50 at pretest that was significantly reduced to 1.59 ± 0.52 and 1.78 ± 0.47 at posttest and follow-up, respectively (P < 0.001. Also, the mean of perceived stress in the TAU group at pretest was 15.9 ± 2.86 and that was changed to 16.13 ± 2.44 and 15.76 ± 2.22 at posttest and follow-up, respectively (P < 0.001. Conclusion: MBSR could reduce stress and improve

  16. Tension pneumocephalus: Mount Fuji sign

    Directory of Open Access Journals (Sweden)

    Pulastya Sanyal

    2015-01-01

    Full Text Available A 13-year-old male was operated for a space occupying lesion in the brain. A noncontrast computed tomography scan done in the late postoperative period showed massive subdural air collection causing compression of bilateral frontal lobes with widening of interhemispheric fissure and the frontal lobes acquiring a peak like configuration - causing tension pneumocephalus-"Mount Fuji sign." Tension pneumocephalus occurs when air enters the extradural or intradural spaces in sufficient volume to exert a mass or pressure effect on the brain, leading to brain herniation. Tension pneumocephalus is a surgical emergency, which needs immediate intervention in the form of decompression of the cranial cavity by a burr hole or needle aspiration. The Mount Fuji sign differentiates tension pneumocephalus from pneumocephalus.

  17. Effect of oocyte maturation time, sperm selection method and oxygen tension on in vitro embryo development in alpacas.

    Science.gov (United States)

    Ruiz, Jaime; Paulo Santayana, R; José Mendoza, M; Leandra Landeo, J; Huamán, Elizabeth; Ticllacuri, Flamel; Fidel Mujica, L; Silva, Mauricio; Ratto, Marcelo H

    2017-06-01

    We evaluated the effect of in vitro maturation time, sperm selection and oxygen tension on alpaca embryo development. In Experiment I, Cumulus Oocyte- Complexes (COCs) were obtained from abattoir ovaries and in vitro matured in TCM-199 for 24 (n = 217), 28 (215), or 32 h (223) at 38.5 °C, high humidity and 5% CO2 in air. Oocytes from 24 (n = 392), 28 (n = 456) or 32 (n = 368) h groups were in vitro fertilized with epididymal sperm and cultured in SOFaa at 38.5 °C, high humidity and 5% CO2, 5% O2 and 90% N2 for 7 days. Embryo development was evaluated on Day 2, 5 and Day 7 of in vitro culture (Day 0 = in vitro fertilization). In Experiment II, a 2 by 2-factorial design was used to determine the effect of sperm selection (Swim-up vs Percoll) and oxygen tension (20% vs 5%) during embryo culture and their interaction on embryo development. COCs were in vitro matured for 32 h at 38.5 °C and 5% CO2 in air and then in vitro inseminated with epididymal sperm processed by swim-up or Percoll. Zygotes were cultured in SOFaa + cumulus cells at 38.5 °C under 20 or 5% of O2 tension and high humidity for 7 days. A total of 235, 235, 253 and 240 oocytes were assigned to: swim-up+20 O2, swim-up+5 O2 or Percoll+20 O2, Percoll+5 O2, groups respectively. The proportion of oocytes reaching MII stage was highest after 32 h of in vitro maturation (P < 0.05). Blastocyst rate (29.1 ± 2.7%) was also highest for COCs matured for 32 h (Exp I). In Experiment II, Blastocysts rate (26.03 ± 4.7; 27.7 ± 4.3; 29.7 ± 3.8 and 27.6 ± 4.2% for swim-up+20 O2, swim-up+5 O2 or Percoll+20 O2, Percoll+5 O2, respectively) was not affected by sperm selection method (P = 0.8), oxygen tension (P = 0.9) or their interaction (P = 0.5). Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Expression of tropomyosin-κ induces dilated cardiomyopathy and depresses cardiac myofilament tension by mechanisms involving cross-bridge dependent activation and altered tropomyosin phosphorylation.

    Science.gov (United States)

    Karam, Chehade N; Warren, Chad M; Rajan, Sudarsan; de Tombe, Pieter P; Wieczorek, David F; Solaro, R John

    2011-03-01

    Tropomyosin-kappa (TPM1-κ) is a newly discovered tropomyosin (TM) isoform that is exclusively expressed in the human heart and generated by an alternative splicing of the α-TM gene. We reported that TPM1-κ expression was increased in the hearts of patients with chronic dilated cardiomyopathy (DCM). To increase our understanding of the significance of this shift in isoform population, we generated transgenic (TG) mice expressing TPM1-κ in the cardiac compartment where TPM1-κ replaces 90% of the native TM. We previously showed that there was a significant inhibition of the ability of strongly bound cross-bridges to induce activation of TG myofilaments (Rajan et al., Circulation 121:410-418, 2010). Here, we compared the force-Ca(2+) relations in detergent extracted (skinned) fiber bundles isolated from non-transgenic (NTG) and TG-TPM1-κ hearts at two sarcomere lengths (SLs). Our data demonstrated a significant decrease in the Ca(2+) sensitivity of the myofilaments from TG-TPM1-κ hearts with no change in the maximum developed tension, length-dependent activation, and the ratio of ATPase rate to tension. There was also no difference in the affinity and cooperativity of Ca(2+)-binding to troponin in thin filaments reconstituted with either TPM1-κ or α-TM. We also compared protein phosphorylation in NTG and TG-TPM1-κ myofilaments. There was a decrease in the total phosphorylation of TPM1-κ compared to α-TM, but no significant change in other major sarcomeric proteins. Our results identify a novel mode of myofilament desensitization to Ca(2+) associated with a DCM linked switch in TM isoform population.

  19. Pre-tension generates strongly reversible adhesion of a spatula pad on substrate.

    Science.gov (United States)

    Chen, Bin; Wu, Peidong; Gao, Huajian

    2009-06-06

    Motivated by recent studies on reversible adhesion mechanisms of geckos and insects, we investigate the effect of pre-tension on the orientation-dependent adhesion strength of an elastic tape adhering on a substrate. Our analysis shows that the pre-tension can significantly increase the peel-off force at small peeling angles while decreasing it at large peeling angles, leading to a strongly reversible adhesion. More interestingly, we find that there exists a critical value of pre-tension beyond which the peel-off force plunges to zero at a force-independent critical peeling angle. We further show that the level of pre-tension required for such force-independent detachment at a critical angle can be induced by simply dragging a spatula pad along a substrate at sufficiently low angles. These results provide a feasible explanation of relevant experimental observations on gecko adhesion and suggest possible strategies to design strongly reversible adhesives via pre-tension.

  20. In tension

    DEFF Research Database (Denmark)

    Bøje, Jakob Ditlev; Nielsen, Steen Baagøe

    Across most of the western world, neo-liberal and neo-conservative tendencies have, since the 1980’s, made their impact on the educational systems of the welfare state. In particular lower and upper secondary school have felt the impact of educational reform, but also higher education and pre...... not been placed under exactly the same regimes of truth and technologies of curriculum, teaching, testing and evaluation as has, for instance, lower and upper secondary school. Instead, pre-school in Denmark is still very much a warehouse for kids (while their parents go to work) and at the same time......-school has been scrutinized and transformed in accordance with ideas about, for instance, higher standards, better teachers, more effective management etc. In a Danish context pre-school somehow seems to have escaped some of the neo-liberal and neo-conservative tendencies. More specifically, pre-school has...

  1. Damage development in woven fabric composites during tension-tension fatigue

    DEFF Research Database (Denmark)

    Hansen, U.

    1999-01-01

    Impacted woven fabric composites were tested in tension-tension fatigue. In contrast to results from static testing, the effects of low energy impact damage in a fatigue environment were found to be the critical element leading to failure of the specimen. This difference emphasizes the need...... to identify and understand the fatigue damage mechanism. A relatively new non-destructive inspection technique using infrared thermography was found to be a very useful tool in detecting damage initiation and growth. Furthermore, this technique supplies valuable information to the characterization...... of the operating fatigue damage mechanism(s). Fatigue leads to a degradation of material properties. Consequently, in connection with impact induced local stress raisers, fatigue produces continuously changing non-uniform stress fields because of stress redistribution effects. Other models addressing evolution...

  2. Demonstration of Surface Tension.

    Science.gov (United States)

    Rosenthal, Andrew J.

    2001-01-01

    Surface tension is a fundamental obstacle in the spontaneous formation of bubbles, droplets, and crystal nuclei in liquids. Describes a simple overhead projector demonstration that illustrates the power of surface tension that can prevent so many industrial processes. (ASK)

  3. The Effect of Text Translation on Perceived Musical Tension in Debussy's "Noel des enfants qui n'ont plus de maisons"

    Science.gov (United States)

    Hackworth, Rhonda S.; Fredrickson, William E.

    2010-01-01

    The primary focus of the present study was to investigate the effect participants' (N = 100) knowledge of a text translation may have on their perceived musical tension while listening to a piece of choral music sung in another language. When examining the graphs that show the group mean responses of the participants, control (without text…

  4. The Effect of Instruction on Children's Perceived Musical Tension in Debussy's "Noel des enfants qui n'ont plus de maisons"

    Science.gov (United States)

    Hackworth, Rhonda S.; Fredrickson, William E.

    2012-01-01

    The study explored possible effects of instruction (highlighting a choral composition's historical and social context) on perceived musical tension recorded by children (N = 62). Children listened to a recording of Debussy's "Noel des enfants qui n'ont plus de maisons" (The Christmas Carol of the Children who No Longer Have a House/Home)…

  5. Travoprost with sofZia® preservative system lowered intraocular pressure of Japanese normal tension glaucoma with minimal side effects.

    Science.gov (United States)

    Mizoue, Shiro; Nakano, Tadashi; Fuse, Nobuo; Iwase, Aiko; Matsumoto, Shun; Yoshikawa, Keiji

    2014-01-01

    This study aimed to evaluate the effect of travoprost with sofZia® preservative system for lowering the intraocular pressure (IOP) of Japanese normal tension glaucoma (NTG) patients. In this prospective, multicenter, open-label study, Japanese NTG patients with baseline IOPs superficial punctate keratopathy, and adverse events were examined at week 4, 8, and 12 after drug instillation. One-hundred and three of the 107 enrolled patients (baseline IOP =15.2±2.0 mmHg [mean ± standard deviation]) completed the study. The mean IOP value as well as percent reduction was significantly reduced at each visit after travoprost with sofZia® initiation (Psuperficial punctate keratopathy. The cumulative incidence of side effects such as eyelash changes, eyelid pigmentation, and deepening of the upper lid was 47.6%, 27.2%, and 16.5%, respectively. Travoprost preserved with sofZia® effectively lowered the IOP of Japanese NTG patients. It was well tolerated with few discontinuations due to adverse events.

  6. Effect of nimodipine on ocular blood flow and colour contrast sensitivity in patients with normal tension glaucoma

    Science.gov (United States)

    Luksch, A; Rainer, G; Koyuncu, D; Ehrlich, P; Maca, T; Gschwandtner, M E; Vass, C; Schmetterer, L

    2005-01-01

    Aim: To investigate the effects of oral nimodipine on ocular haemodynamic parameters and colour contrast sensitivity in patients with normal tension glaucoma (NTG). Design: The study was performed in a randomised, placebo controlled, double masked, crossover design. Participants: Nimodipine (60 mg) or placebo was administered to 14 consecutive NTG patients. Methods: The effects or oral nimodipine or placebo on ocular and systemic haemodynamic parameters and colour contrast sensitivity along the tritan axis were studied two hours after administration. Optic nerve head blood flow (ONHBF) and choroidal blood flow (CHBF) were assessed with laser Doppler flowmetry. Ocular fundus pulsation amplitude (FPA) was measured with laser interferometry. Colour contrast sensitivity (CCS) was determined along the tritan colour axis. Main outcome measures: ONHBF, CHBF, FPA, intraocular pressure and CCS were assessed in patients with NTG. Results: Mean ocular FPA increased by 14% (SD 14%) (p = 0.0008), ONHBF by 18% (SD 16%) (p = 0.0031), and CHBF by 12% (SD 14%) (pnimodipine. Nimodipine also decreased the threshold of colour contrast sensitivity along the tritan colour axis (−14% (SD 12%); p = 0.048). However, individual changes in FPA, ONHBF, or CHBF were not correlated with changes in threshold of CCS along the tritan colour axis. Conclusions: The results indicate that nimodipine increases ONH and choroidal blood flow in NTG patients and improves CCS. The latter effect does not, however, seem to be a direct consequence of the blood flow improvement. PMID:15615740

  7. Comparing effectiveness of combined transobturator tension-free vaginal mesh (Perigee) and transobturator tension-free vaginal tape (TVT-O) versus anterior colporrhaphy and TVT-O for associated cystocele and urodynamic stress incontinence.

    Science.gov (United States)

    Lau, Hei-Yu; Twu, Nae-Fang; Chen, Yi-Jen; Horng, Huann-Cheng; Juang, Chi-Mou; Chao, Kuan-Chong

    2011-06-01

    To evaluate the efficacy and safety of transobturator tension-free vaginal mesh (Perigee) and concomitant transobturator tension-free vaginal tape (TVT-O) for treating cystocele with urodynamic stress incontinence (UDSI). A retrospective study of 115 patients with symptomatic stages 2-3 cystocele and UDSI who were treated with a Perigee system (Group I, n=68) plus TVT-O procedure or traditional anterior colporrhaphy (Group II, n=47) plus TVT-O procedure. All patients were followed up for more than one year. Objective and subjective symptoms were evaluated at one year postoperatively. Statistical analysis was performed using SPSS software. The objective cure rates for cystocele at one year were significantly higher in Group I than in Group II (98.5% and 86.9%, P=0.018), respectively. The cure rates for UDSI in the two groups were 91.0% vs. 91.3% (P=1.000). Symptomatic improvement of frequency was better in Group I than Group II (87.7% vs. 70.0%, P=0.030). There were no significant differences with regard to intraoperative and postoperative complications between the two groups. The combination of the Perigee system and TVT-O offers a safe and effective treatment for cystocele with UDSI and may be performed as first-line treatment. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  8. Effects of Singing Bowl Sound Meditation on Mood, Tension, and Well-being: An Observational Study

    National Research Council Canada - National Science Library

    Goldsby, Tamara L; Goldsby, Michael E; McWalters, Mary; Mills, Paul J

    Poor mood and elevated anxiety are linked to increased incidence of disease. This study examined the effects of sound meditation, specifically Tibetan singing bowl meditation, on mood, anxiety, pain, and spiritual well-being...

  9. Synergistic Effects of Frequency and Temperature on Damage Evolution and Life Prediction of Cross-Ply Ceramic Matrix Composites under Tension-Tension Fatigue Loading

    Science.gov (United States)

    Longbiao, Li

    2017-10-01

    In this paper, the synergistic effects of loading frequency and testing temperature on the fatigue damage evolution and life prediction of cross-ply SiC/MAS ceramic-matrix composite have been investigated. The damage parameters of the fatigue hysteresis modulus, fatigue hysteresis dissipated energy and the interface shear stress were used to monitor the damage evolution inside of SiC/MAS composite. The evolution of fatigue hysteresis dissipated energy, the interface shear stress and broken fibers fraction versus cycle number, and the fatigue life S-N curves of SiC/MAS composite under the loading frequency of 1 and 10 Hz at 566 °C and 1093 °C in air condition have been predicted. The synergistic effects of the loading frequency and testing temperature on the degradation rate of fatigue hysteresis dissipated energy and the interface shear stress have been analyzed.

  10. Bone Formation and Skeletal Aging - The effects of oxygen tension and DNA repair

    NARCIS (Netherlands)

    C. Nicolaije (Claudia)

    2012-01-01

    textabstractAging is a process that affects everybody and importantly, affects all cells and therefore all the tissues in our body. In the worst cases, tissue aging leads to organ failure and death; in other cases, the effects of aging are more subtle and less dramatic. In our tissue of choice –

  11. Effect of oxygen tension on adult articular chondrocytes in microcarrier bioreactor culture

    NARCIS (Netherlands)

    Malda, J.; Brink, van den P.; Meeuwse, P.; Grojec, M.; Martens, D.E.; Tramper, J.; Riesle, J.; Blitterswijk, van C.A.

    2004-01-01

    Tissue-engineering approaches for cartilage repair hold promise for the treatment of cartilage defects. Various methods to prevent or reduce dedifferentiation during chondrocyte expansion are currently under investigation. In the present study we evaluated the effect of oxygen on chondrocyte

  12. Mechanical tension in the median nerve: The effects of joint positions

    NARCIS (Netherlands)

    G.J. Kleinrensink (Gert Jan); R. Stoeckart (Rob); A. Vleeming (Andry); C.J. Snijders (Chris); P.G.H. Mulder (Paul)

    1995-01-01

    textabstractStretch tests are attractive in the diagnosis of nerve root or peripheral nerve lesion. Interpretation of the test results is often difficult since the distribution of tensile forces along the nerve caused by the test manoeuvre is not known. In this study the effect on median nerve

  13. Effect of vanadate and of removal of extracellular Ca2+ and Na+ on tension development and 45Ca efflux in rat and frog myocardium

    DEFF Research Database (Denmark)

    Gesser, H; Bonefeld-Jørgensen, Eva Cecilie

    1983-01-01

    Vanadate in the range 0-5 mM has positive inotropic effects on myocardial strips of frog and to a lesser extent on those of rat. Inhibiting the sarcolemmal Na+, Ca2+ exchange by a solution free of Ca2+ and Na+ caused a drop in 45Ca efflux and a transient increase in resting tension. These effects...... were more expressed for the frog than for the rat myocardium, which suggests that the Na+ for Ca2+ exchange across the cell membrane is more important in the frog than in the rat myocardium. A subsequent addition of vanadate at 2 or 5 mM had no effect on 45Ca efflux, while it increased the resting...... tension. This increase was higher for the frog than for the rat myocardium. These results suggest that the inotropic effects of vanadate may be due to an effect on membrane-bound Ca2+-ATPase....

  14. Effects of Al(OH)O nanoparticle agglomerate size in epoxy resin on tension, bending, and fracture properties

    Energy Technology Data Exchange (ETDEWEB)

    Jux, Maximilian, E-mail: maximilian.jux@dlr.de [TU Braunschweig, Institute of Adaptronic and Functional Integration (IAF) (Germany); Finke, Benedikt [TU Braunschweig, Institute for Particle Technology (IPAT) (Germany); Mahrholz, Thorsten [DLR Braunschweig, Institute of Composite Structures and Adaptive Systems (FA) (Germany); Sinapius, Michael [TU Braunschweig, Institute of Adaptronic and Functional Integration (IAF) (Germany); Kwade, Arno; Schilde, Carsten [TU Braunschweig, Institute for Particle Technology (IPAT) (Germany)

    2017-04-15

    Several epoxy Al(OH)O (boehmite) dispersions in an epoxy resin are produced in a kneader to study the mechanistic correlation between the nanoparticle size and mechanical properties of the prepared nanocomposites. The agglomerate size is set by a targeted variation in solid content and temperature during dispersion, resulting in a different level of stress intensity and thus a different final agglomerate size during the process. The suspension viscosity was used for the estimation of stress energy in laminar shear flow. Agglomerate size measurements are executed via dynamic light scattering to ensure the quality of the produced dispersions. Furthermore, various nanocomposite samples are prepared for three-point bending, tension, and fracture toughness tests. The screening of the size effect is executed with at least seven samples per agglomerate size and test method. The variation of solid content is found to be a reliable method to adjust the agglomerate size between 138–354 nm during dispersion. The size effect on the Young’s modulus and the critical stress intensity is only marginal. Nevertheless, there is a statistically relevant trend showing a linear increase with a decrease in agglomerate size. In contrast, the size effect is more dominant to the sample’s strain and stress at failure. Unlike microscaled agglomerates or particles, which lead to embrittlement of the composite material, nanoscaled agglomerates or particles cause the composite elongation to be nearly of the same level as the base material. The observed effect is valid for agglomerate sizes between 138–354 nm and a particle mass fraction of 10 wt%.

  15. Short-term effects of traditional Thai massage on electromyogram, muscle tension and pain among patients with upper back pain associated with myofascial trigger points.

    Science.gov (United States)

    Buttagat, Vitsarut; Narktro, Thitipong; Onsrira, Kamonporn; Pobsamai, Chaithawat

    2016-10-01

    To investigate effects of traditional Thai massage (TTM) on electromyographic (EMG) activity, muscle tension and pain intensity in patients with upper back pain associated with myofascial trigger points (MTrPs). A single-blind, randomized clinical trial. The Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Thailand. Fifty patients were randomly assigned to receive a 30-min session of either TTM or control (sham microwave diathermy). Electromyogram (EMG), Muscle tension rating, and pain intensity rating TTM were associated with significant decreases in EMG, muscle tension and pain intensity after the end of treatment session (p0.05) except for muscle tension (p<0.05). In addition, there was a significantly greater reduction in all parameters for the TTM group when compared with the control group. We therefore suggest that TTM can increase physical relaxation and reduce pain in patients with upper back pain associated with MTrPs. ClinicalTrials.gov Identifier: NCT02067325. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Parametric Study of the Effect of Membrane Tension on Sunshield Dynamics

    Science.gov (United States)

    Ross, Brian; Johnston, John D.; Smith, James

    2002-01-01

    The NGST sunshield is a lightweight, flexible structure consisting of pretensioned membranes supported by deployable booms. The structural dynamic behavior of the sunshield must be well understood in order to predict its influence on observatory performance. A 1/10th scale model of the sunshield has been developed for ground testing to provide data to validate modeling techniques for thin film membrane structures. The validated models can then be used to predict the behaviour of the full scale sunshield. This paper summarizes the most recent tests performed on the 1/10th scale sunshield to study the effect of membrane preload on sunshield dynamics. Topics to be covered include the test setup, procedures, and a summary of results.

  17. Viscosity and surface tension effects during multiphase flow in propped fractures

    Science.gov (United States)

    Dzikowski, Michał; Dąbrowski, Marcin

    2017-04-01

    Geological sequestration of CO2 was proposed as an important mechanism to reduce its emission into atmosphere. CO2 exhibits a higher affinity to organic matter than methane molecules and, potentially, it could be pumped and stored in shale reservoirs while enhancing late stage shale gas production. A successful analysis of CO2 sequestration in low matrix permeability rocks such as shales requires a thorough understanding of multiphase flow in stimulated rock fractures, which provide most significant pathways for fluids in such systems. Multiphase fracture flows are also of great relevance to brine, oil and gas migration in petroleum systems, water and stream circulation in geothermal reservoirs, and chemical transport of non-aqueous phase liquids in shallow hydrogeological systems, particularly in partially saturated zones. There are various physical models that describe phenomena taking place during multiphase flow through porous media. One of key aspects that need to be considered are pore-scale effects related to capillarity. Unfortunately, detailed models that describe motion and evolution of phase or component boundary require direct numerical simulations and spatial resolutions that are hard to reach when considering industrial relevant systems. Main aim of the presented work was the development of reduced 2.5D models based on Brinkman approximation of thin domain flow that would be able to capture local scale phenomena without expensive 3D simulations. Presented approach was designed specifically to tackle incompressible and immiscible systems and is based on Continuous Surface Force approach presented by Brackbill et al., implemented using Lattice Boltzmann Method. Presented approach where firstly validated against standard test cases with known classical solution and known experimental data. In the second part, we present and discuss two component, immiscible permeability data for rough and propped fracture obtained with our code for a rage of proppants

  18. Permanent tensions in organization.

    Science.gov (United States)

    Jansson, Noora

    2015-01-01

    The purpose of this paper is to investigate the relationship between permanent tensions and organizational change. This study used paradox theory and a case study. The case organization is a public university hospital in Finland involving several stakeholders. The analysis suggests that the relationship between permanent tensions and organizational change is a paradox that is part of organizational reality. As an organization learns to live with its permanent tensions, the renewal paradox settles into equilibrium. When tensions are provoked, the paradox is disturbed until it finds a new balance. This flexible nature of the paradox is the force that keeps the different stakeholders simultaneously empowered to maintain their unique missions and cohesive in order to benefit from the larger synergy. This research suggests that identification and evaluation of each permanent tension within an organization is important when executing organizational change. The fact that certain tensions are permanent and cannot be solved may have an influence on how planned change initiatives are executed. The results show that permanent tensions may be harnessed for the benefit of an organizational change. This research demonstrates originality by offering an alternative view of tensions, a view which emphasizes not only their permanent and plural nature but their importance for enabling the organization to change at its own, non-disruptive pace. The research also proposes a new concept, the "renewal paradox", to enhance understanding of the relationship between permanent tensions and organizational change.

  19. A Multiparameter Damage Constitutive Model for Rock Based on Separation of Tension and Shear

    Directory of Open Access Journals (Sweden)

    YanHui Yuan

    2015-01-01

    Full Text Available By analysis of the microscopic damage mechanism of rock, a multiparameter elastoplastic damage constitutive model which considers damage mechanism of tension and shear is established. A revised general form of elastoplastic damage model containing damage internal variable of tensor form is derived by considering the hypothesis that damage strain is induced by the degeneration of elastic modulus. With decomposition of plastic strain introduced, the forms of tension damage variable and shear damage variable are derived, based on which effects of tension and shear damage on material’s stiffness and strength are considered simultaneously. Through the utilizing of Zienkiewicz-Pande criterion with tension limit, the specific form of the multiparameter damage model is derived. Numerical experiments show that the established model can simulate damage behavior of rock effectively.

  20. Tension type headaches: a review

    African Journals Online (AJOL)

    Acetaminophen (paracetamol) 500-1 000 mg and aspirin 500-. 1 000 mg, have been demonstrated to be an effective first-line treatment for episodic tension-type headaches in most placebo- controlled trials. 23,24 Fast absorptive formulations of the latter are preferred for rapidity of action.25 It is worth noting that these.

  1. Molecular-Level Insight of the Effect of Hofmeister Anions on the Interfacial Surface Tension of a Model Protein

    Energy Technology Data Exchange (ETDEWEB)

    Willow, Soohaeng Yoo; Xantheas, Sotiris S.

    2017-03-21

    The effect of the Hofmeister anion series on the structure and stability of proteins is often discussed using simple systems such as a water-vapor interface with the assumption that the vapor region mimics the hydrophobic surface. Microscopic theories suggest that the Hofmeister anion series is highly correlated with the different contributions of the various ions to the surface tension of such a water-vapor interface. Proteins, however, have both hydrophobic and hydrophilic regions rather than just a pure hydrophobic one. Using a solvated parallel β -sheet layer consisting of both hydrophobic and positively charged hydrophilic surfaces as a more realistic model to represent a protein surface, we investigated the interaction of such a system with hydrophilic-like (SO42-) and hydrophobic-like (ClO4-) anions via Born-Oppenheimer Molecular Dynamics (BOMD) simulations. We found that both the SO42- and ClO4- anions prefer to reside on the hydrophilic rather than on the hydrophobic surface of the parallel β -sheet layer. In addition, our simulations suggest that the ClO4- ions not only penetrate towards the peptide groups through the hydrophilic residues, but also allow water molecules to penetrate as well to form water-peptide hydrogen bonds, while the SO42- ions stabilize the interface of the water-hydrophilic surface. Our results render a plausible explanation of why hydrophobic-like Hofmeister anions act as protein denaturants. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  2. Surface Tension Measurements of Chemically Modified Oleochemical

    Science.gov (United States)

    Surface tension is an important physical property of a substance, which plays a part in a variety of physical phenomenon relevant to many industrial processes. For example, the efficiency of the atomization of a fuel has been shown to be effected dramatically by surface tension and viscosity. Beca...

  3. Effect of two hydrocarbon and one fluorocarbon surfactant mixtures on the surface tension and wettability of polymers.

    Science.gov (United States)

    Szymczyk, Katarzyna; González-Martín, Maria Luisa; Bruque, Jose Morales; Jańczuk, Bronisław

    2014-03-01

    The advancing contact angle of water, formamide and diiodomethane on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) surfaces covered with the film of ternary mixtures of surfactants including p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethyleneglycols), Triton X-100 (TX100) and Triton X-165 (TX165) and the fluorocarbon surfactants, Zonyl FSN-100 (FSN100) or Zonyl FSO-100 (FSO100) was measured. The obtained results were used for the surface tension of PTFE and PMMA covered with this film determination from the Young equation on the basis of van Oss et al. and Neumann et al. approaches to the interfacial tension. The surface tension of PTFE and PMMA was also determined using the Neumann et al. equation and the contact angle values for the aqueous solutions of the above mentioned ternary surfactants mixtures which were taken from the literature. As follows from our calculations mainly the presence of the fluorocarbon surfactant in the mixture considerably changes the surface properties of PTFE and PMMA causing that in contrast to hydrocarbon surfactants and their mixtures there is no linear dependence between adhesion and surface tension in the whole range of concentration of the ternary mixtures of surfactants including the fluorocarbon one. The behavior of fluorocarbon surfactants at the polymer-air and polymer-water interfaces is quite different from those of hydrocarbons. In the case of fluorocarbon surfactants not only adsorption but also sorption can occur on the polymer surface. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Effects of physical therapy and relaxation techniques on the parameters of pain in university students with tension-type headache: A randomised controlled clinical trial.

    Science.gov (United States)

    Álvarez-Melcón, A C; Valero-Alcaide, R; Atín-Arratibel, M A; Melcón-Álvarez, A; Beneit-Montesinos, J V

    2016-08-01

    Non-pharmacological treatments help control tension-type headache; however, evidence about their effectiveness is still limited. This study evaluates the effectiveness of physical therapy based on cervical spine kinesiotherapy and posture correction exercises compared to a programme of relaxation techniques only (Schultz's Autogenic Training, AT). Tension-type headache is very common among university students. We randomly selected 152 university students with a diagnosis of tension-type headache according to the criteria of the International Headache Society. Eighty-four were women (55.3%) and 68 were men (44.7%). Mean age was 20.42±2.36 years. The study design is a randomised controlled trial of a non-pharmacological intervention with a blinded evaluation of response variables. We compared the results of two independent samples: AT was used in one of the groups while the other group received AT plus cervical spine kinesiotherapy and posture correction training. Patients recorded any changes in the parameters of pain (frequency, intensity, and duration) and drug consumption in a headache diary before treatment, at 4 weeks, and at 3 months. Both interventions achieved a decrease in all the parameters of pain; however, decreases in frequency and intensity were more significant in the combined treatment group (P<0.01) (d=0.4). Such active, non-invasive therapies as AT and cervical spine kinesiotherapy, and especially the combination of both, effectively reduce tension-type headache by preventing and managing the potential psychophysical causes of this disorder. Future research should aim to assess the long-term effects of these interventions. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  5. Effect of progressive muscular relaxation exercises versus transcutaneous electrical nerve stimulation on tension headache: A comparative study

    Directory of Open Access Journals (Sweden)

    Sanjiv Kumar, MPT, PhD

    2014-12-01

    Full Text Available Tension-type headache (TTH is most frequent among all types of headaches. According to the International Headache Classification Subcommittee of the International Headache Society (2004, TTH occurs in 30–78% of the population. Progressive muscular relaxation exercises have been shown to reduce TTH, and home-based relaxation programmes can result in significant improvement in headaches. Transcutaneous electrical nerve stimulation (TENS is a method of electrical stimulation that primarily aims to provide a degree of symptomatic pain relief by exciting sensory nerves and stimulating either the pain gate mechanisms or the opioid systems. The objective of this study was to compare between the effects of progressive muscular relaxation exercises and TENS on pain intensity and stress in people with TTH. Thirty patients with TTH were allocated to either Group A or Group B. Group A practised progressive muscular relaxation exercise, whereas Group B received TENS. In the latter group, TENS electrodes were placed bilaterally either on the head at the site of pain or on the occiput. The treatment was carried out for 15 minutes a day, for 7 days. Patients were assessed for pain intensity (Visual Analogue Scale and level of stress (Lakaev Academic Stress Response Scale before and after the intervention period. The results showed that progressive muscular relaxation exercises were effective in reducing pain as well as stress (p < 0.001. TENS, by contrast, reduced stress significantly (p < 0.001, but not pain (p = 0.233. Between-group analysis revealed that there was no statistically significant difference in reduction of pain between the two groups (p = 0.595, but the amount of stress reduction in Group A (p = 0.002 was significantly more than that in Group B. In conclusion, progressive muscular relaxation exercises were more effective in reducing stress level than TENS in patients with TTH. The effect on pain reduction was similar between the two

  6. The effect of rotator cuff malreduction on tendon tension: an evaluation of a custom-made digital tensiometer clamp.

    Science.gov (United States)

    Pastor, Marc-Frederic; Kraemer, Manuel; Schwarze, Michael; Hurschler, Christof; Smith, Tomas; Wellmann, Mathias

    2017-10-27

    Rotator cuff tears are common and good-to-excellent clinical outcome is reported after subsequent repair. However, the retear rate of rotator cuff repairs has been shown to be as high as 20%. The reasons for retear seem to be multifactorial, mainly comprised by mechanical and biological aspects. Regarding mechanical causes, the role of the tendon tension and malreduction is so far unknown. First, we hypothesized that the tendon tension depends on the technique of tendon reposition and that malreduction of the tendon results in an increased tendon tension. Second, we aimed to demonstrate the inter- and intraobserver reliability of a novel custom-made digital tensiometer clamp. A tendon defect of posterosuperior rotator cuff (reverse L-shaped) was simulated in seven cadaveric human shoulder specimens. By use of a custom-made tensiometer clamp, the supraspinatus tendon was reduced by pulling it in (1) an anterolateral direction (anatomical reduction) and (2) in a straight lateral direction (malreduction) until the footprint was completely covered. The reduction procedure was consecutively repeated to evaluate the inter- and intraobserver reliability. The mean traction forces for anatomical reduction and malreduction were 16.02 N (SD 8.06) and 19.52 N (SD 9.95), respectively. The difference between the two groups was statistically significant (p = 0.028). The interobserver reliability showed a correlation of r = 0.757 [95% confidence interval (CI) 0.092-0.955]. The intraobserver reliability of the three surgeons was observed to be between r = 0.905 and 0.986. The malreduction of the rotator cuff has a significant influence on the tendon tension and may therefore affect the healing rate of the tendon after the repair, so that a tension-balanced repair could improve the clinical results. Furthermore, the application of a novel custom-made tensiometer clamp showed good interobserver and excellent intraobserver reliabilities.

  7. Headache (chronic tension-type).

    Science.gov (United States)

    Krishnan, Anita; Silver, Nicholas

    2009-07-22

    Chronic tension-type headache (CTTH) is a disorder that evolves from episodic tension-type headache, with daily or very frequent episodes of headache lasting minutes to days. It affects 4.1% of the general population in the USA, and is more prevalent in women (up to 65% of cases). We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments for chronic tension-type headache? What are the effects of non-drug treatments for chronic tension-type headache? We searched: Medline, Embase, The Cochrane Library, and other important databases up to March 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 50 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acupuncture; amitriptyline; analgesics; anticonvulsant drugs; benzodiazepines; botulinum toxin; chiropractic and osteopathic manipulations; cognitive behavioural therapy (CBT); Indian head massage; mirtazapine; relaxation and electromyographic biofeedback; selective serotonin reuptake inhibitor antidepressants (SSRIs); and tricyclic antidepressants (other than amitriptyline).

  8. Tensions in Distributed Leadership

    Science.gov (United States)

    Ho, Jeanne; Ng, David

    2017-01-01

    Purpose: This article proposes the utility of using activity theory as an analytical lens to examine the theoretical construct of distributed leadership, specifically to illuminate tensions encountered by leaders and how they resolved these tensions. Research Method: The study adopted the naturalistic inquiry approach of a case study of an…

  9. Therapeutic effects of traditional Thai massage on pain, muscle tension and anxiety in patients with scapulocostal syndrome: a randomized single-blinded pilot study.

    Science.gov (United States)

    Buttagat, Vitsarut; Eungpinichpong, Wichai; Chatchawan, Uraiwon; Arayawichanon, Preeda

    2012-01-01

    The purpose of this study was to investigate the therapeutic effects of traditional Thai massage (TTM) on pain intensity, pressure pain threshold (PPT), muscle tension and anxiety associated with scapulocostal syndrome (SCS). Twenty patients were randomly allocated to receive a 30-min session of either TTM or physical therapy modalities (PT: ultrasound therapy and hot pack) for 9 sessions over a period of 3 weeks. Pain intensity, PPT, muscle tension and anxiety were measured before and immediately after the first treatment session, 1 day after the last treatment session and 2 weeks after the last treatment session. Results indicated that the TTM group showed a significant improvement in all parameters after the first treatment session and at 1 day and 2 weeks after the last treatment session (p  0.05). We therefore suggest that TTM could be an alternative treatment for the patient with SCS. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Effect of Elastase-induced Emphysema on the Force-generating Ability of the Diaphragm

    Science.gov (United States)

    Supinski, Gerald S.; Kelsen, Steven G.

    1982-01-01

    The effect of emphysema on the ability of the diaphragm to generate force was examined in costal diaphragm muscle strips from 10 Golden hamsters killed 18 mo after intratracheal injection of pancreatic elastase in a dose producing hyperinflation (mean total lung capacity [TLC] = 163% of control) and generalized panacinar emphysema. 13 saline-injected normal animals served as controls. The time course of isometric tension and the effect of alterations in muscle fiber and sarcomere length on the isometric tension (T) generated in response to tetanizing electrical stimuli (length-tension [L-T] relationship) were examined. Elastase administration caused an increase in diaphragm muscle thickness and reduction in the length of costal diaphragm muscle fibers measured in situ. Emphysema significantly increased the maximum tetanic tension as a result of hypertrophy. Maximal tension corrected for increases in muscle cross-sectional area (T/cm2), however, was the same in emphysematous (E) and control (C) animals. Emphysema also shifted the muscle fiber L-T curve of the diaphragm but not of a control muscle, the soleus, toward shorter lengths. In contrast to the effects of E on the diaphragm muscle fiber L-T curve, the sarcomere L-T curve was the same in E and C. Since the length at which tension was maximal correlated closely with sarcomere number (r = 0.94; P < 0.001) reduction in the number of sarcomeres in series in muscles from emphysematous animals appeared to explain the shift in the muscle fiber L-T curve. We conclude that in elastase-induced emphysema adaptive changes both in diaphragm cross-sectional area and sarcomere number augment the force-generating ability of the diaphragm. We speculate that changes in sarcomere number compensate for alterations in muscle fiber length resulting from chronic hyperinflation of the thorax, while diaphragmatic muscle hypertrophy represents a response to changes in respiratory load and/or diaphragm configuration (La

  11. Effect of mindfulness-based stress reduction on pain severity and mindful awareness in patients with tension headache: a randomized controlled clinical trial.

    Science.gov (United States)

    Omidi, Abdollah; Zargar, Fatemeh

    2014-09-01

    Programs to improve the pain and health status in illnesses with pain such as headache are still in their infancy. Mindfulness-based stress reduction (MBSR) is a new psychotherapy that appears to be effective in treating chronic pain. This study evaluated efficacy of MBSR in improving pain severity and mindful awareness in patients with tension headache. This study was a randomized controlled clinical trial that was conducted in 2012 in Shahid Beheshti Hospital of Kashan City. Sixty patients who were diagnosed with tension-type headache according to the International Headache Classification Subcommittee were randomly assigned to treatment as usual (TAU) or MBSR groups. The MBSR group received eight weekly treatments. Any session lasted 120 minutes. The sessions were based on MBSR protocol. Diary scale for measuring headache and Mindful Attention Awareness Scale (MAAS) were administered at pretreatment, and posttreatment, and three-month follow-up in both groups. The data was analyzed using repeated measures analysis of variance. The mean of pain severity was 7.36 ± 1.25 before intervention that was significantly reduced to 5.62 ± 1.74 and 6.07 ± 1.08 after the intervention and follow-up (P MBSR group showed higher scores in mindful awareness in comparison with the control group at posttest session. The mean of mindful awareness before intervention was 34.9 ± 10.5 and changed to 53.8 ± 15.5 and 40.7 ± 10.9 after the intervention and follow-up sessions (P MBSR could reduce pain and improve mindfulness skills in patients with tension headache. It appears that MBSR is an effective psychotherapy for treatment of patients with tension headache.

  12. The effect of a curvature-dependent surface tension on the singularities at the tips of a straight interface crack

    KAUST Repository

    Zemlyanova, A. Y.

    2013-03-08

    A problem of an interface crack between two semi-planes made out of different materials under an action of an in-plane loading of general tensile-shear type is treated in a semi-analytical manner with the help of Dirichlet-to-Neumann mappings. The boundaries of the crack and the interface between semi-planes are subjected to a curvature-dependent surface tension. The resulting system of six singular integro-differential equations is reduced to the system of three Fredholm equations. It is shown that the introduction of the curvature-dependent surface tension eliminates both classical integrable power singularity of the order 1/2 and an oscillating singularity present in a classical linear elasticity solutions. The numerical results are obtained by solving the original system of singular integro-differential equations by approximating unknown functions with Taylor polynomials. © 2013 The Author.

  13. Thermocapillary-driven motion of a sessile drop: effect of non-monotonic dependence of surface tension on temperature.

    Science.gov (United States)

    Karapetsas, George; Sahu, Kirti Chandra; Sefiane, Khellil; Matar, Omar K

    2014-04-22

    We study the thermocapillary-driven spreading of a droplet on a nonuniformly heated substrate for fluids associated with a non-monotonic dependence of the surface tension on temperature. We use lubrication theory to derive an evolution equation for the interface that accounts for capillarity and thermocapillarity. The contact line singularity is relieved by using a slip model and a Cox-Voinov relation; the latter features equilibrium contact angles that vary depending on the substrate wettability, which, in turn, is linked to the local temperature. We simulate the spreading of droplets of fluids whose surface tension-temperature curves exhibit a turning point. For cases wherein these turning points correspond to minima, and when these minima are located within the droplet, then thermocapillary stresses drive rapid spreading away from the minima. This gives rise to a significant acceleration of the spreading whose characteristics resemble those associated with the "superspreading" of droplets on hydrophobic substrates. No such behavior is observed for cases in which the turning point corresponds to a surface tension maximum.

  14. The effect of a soap film on a catenary: measurement of surface tension from the triangular configuration

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, F [Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614 (United States); Behroozi, P S, E-mail: behroozi@uni.edu [Department of Physics, Stanford University, Stanford, CA 94305 (United States)

    2011-09-15

    A chain assumes the well-known shape known as a catenary when it hangs loosely from two points in a gravitational field. The correct solution of the catenary was one of the early triumphs of the newly invented calculus of variations at the end of the 17th century. Here we revisit the catenary and show that, for a chain hanging from a horizontal rod, three new and distinct configurations are possible if a soap film covers the area bounded by the chain and the rod. We first review the general problem and discuss the conditions under which the chain assumes a concave, triangular or convex configuration. The deciding factor is the strength of surface tension relative to the gravitational force per unit length of the chain. The conditions under which the chain assumes the shape of a perfect triangle are discussed in greater detail and analysed to obtain the tension along the chain. The triangular configuration is especially intriguing to undergraduates and may be used as a simple experiment to obtain the surface tension of the soap solution by measuring just one angle of the triangle.

  15. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2015-08-01

    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. The effect of the volume fraction and viscosity on the compression and tension behavior of the cobalt-ferrite magneto-rheological fluids

    Directory of Open Access Journals (Sweden)

    H. Shokrollahi

    2016-03-01

    Full Text Available The purpose of this work is to investigate the effects of the volume fraction and bimodal distribution of solid particles on the compression and tension behavior of the Co-ferrite-based magneto-rheological fluids (MRFs containing silicon oil as a carrier. Hence, Co-ferrite particles (CoFe2O4 with two various sizes were synthesized by the chemical co-precipitation method and mixed so as to prepare the bimodal MRF. The X-Ray Diffraction (XRD analysis, Fourier Transform Infrared Spectroscopy (FTIR, Laser Particle Size Analysis (LPSA and Vibrating Sample Magnetometer (VSM were conducted to examine the structural and magnetic properties, respectively. The results indicated that the increase of the volume fraction has a direct increasing influence on the values of the compression and tension strengths of fluids. In addition, the compression and tension strengths of the mixed MRF sample (1.274 and 0.647 MPa containing 60 and 550 nm samples were higher than those of the MRF sample with the same volume fraction and uniform particle size of 550 nm.

  17. The effect of foetal growth restriction on the development of migraine and tension-type headache in adulthood. The HUNT Study.

    Directory of Open Access Journals (Sweden)

    Sigrid Børte

    Full Text Available There is little knowledge about how factors early in life affect the development of migraine and tension-type headache. We aimed to examine whether growth restriction in utero is associated with development of migraine and frequent tension-type headache in adults.The population-based Nord-Trøndelag Health Study (HUNT 3 contained a validated headache questionnaire, which differentiated between migraine and tension-type headache. These data were linked to information on weight and gestational age at birth from the Norwegian Medical Birth Registry. In total 4557 females and 2789 males, aged 19-41 years, were included in this registry-based study. Participants were categorized as appropriate for gestational age (AGA, 10th-90th percentile, small for gestational age (SGA, 3rd-10th percentile or very small for gestational age (VSGA, < 3rd percentile. Logistic regression was used to calculate odds ratios (OR with 95% confidence intervals (CI for migraine and tension-type headache, with exposure being growth restriction at birth.The effect of growth restriction on migraine was modified by sex, with a significant association in males (p<0.001, but not in females (p = 0.20. In particular, males born VSGA were at increased risk of developing migraine (OR 2.73, 95% CI 1.63-4.58, p<0.001, with an intermediate risk among those born SGA (OR 1.50, 95% CI 0.96-2.35, p = 0.08 compared to those born AGA. There was no significant association between growth restriction and frequent TTH (p = 0.051.Growth restriction was associated with increased risk of migraine in adulthood among males, but not among females. This suggests that migraine might, in part, be influenced by early life events, and that males seem to be particularly vulnerable.

  18. Effect of oxygen tension on the generation of F2-isoprostanes and malondialdehyde in peroxidizing rat liver microsomes.

    Science.gov (United States)

    Longmire, A W; Swift, L L; Roberts, L J; Awad, J A; Burk, R F; Morrow, J D

    1994-03-29

    Although numerous methods have been developed for the detection of lipid peroxidation, it is generally recognized that most of these lack specificity and/or sensitivity, particularly when applied to in vivo situations. We have reported recently that a series of prostaglandin F2-like compounds, termed F2-isoprostanes, are formed in vivo from the free radical catalyzed peroxidation of arachidonic acid and appear to be a useful marker of oxidant stress. Because of formation of other products of lipid peroxidation, such as alkanes and malondialdehyde (MDA), are affected by oxygen tension, which may influence their usefulness as markers of oxidant stress, we carried out a systematic study of the generation of F2-isoprostanes at various oxygen concentrations and compared these changes with the generation of MDA. The disappearance of the F2-isoprostane precursor, arachidonic acid, was used as a reference measure. Rat liver microsomes were peroxidized using an iron-ascorbate system. The incubations were carried out in sealed flasks at 37 degrees under N2 and various concentrations of O2 up to 100%. F2-isoprostanes were quantified by mass spectrometry and MDA by the thiobarbituric acid reaction. Microsomal fatty acids were measured by gas chromatography. Both MDA and F2-isoprostane formation increased in a time-dependent manner up to 15 min. Their formation correlated with a loss of polyunsaturated fatty acid and with an increase in O2 tension up to 21% O2. At oxygen tensions above 21%, MDA generation continued to increase, while F2-isoprostane generation and arachidonic acid loss did not. Levels of MDA and F2-isoprostanes increased a maximum of 65 and 9.4 times baseline values, respectively. These studies, therefore, define factors that influence the formation of F2-isoprostanes in an in vitro model of lipid peroxidation. Further, they demonstrate that higher O2 tensions do not block formation of F2-isoprostanes and validate their usefulness for assessing lipid

  19. Oxygen tension level and human viral infections

    Energy Technology Data Exchange (ETDEWEB)

    Morinet, Frédéric, E-mail: frederic.morinet@sls.aphp.fr [Centre des Innovations Thérapeutiques en Oncologie et Hématologie (CITOH), CHU Saint-Louis, Paris (France); Université Denis Diderot, Sorbonne Paris Cité Paris, Paris (France); Casetti, Luana [Institut Cochin INSERM U1016, Paris (France); François, Jean-Hugues; Capron, Claude [Institut Cochin INSERM U1016, Paris (France); Laboratoire d' Hématologie, Hôpital Ambroise Paré, Boulogne (France); Université de Versailles Saint-Quentin en Yvelynes, Versailles (France); Pillet, Sylvie [Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Saint-Etienne, Saint-Etienne (France); Université de Lyon et Université de Saint-Etienne, Jean Monnet, GIMAP EA3064, F-42023 Saint-Etienne, Lyon (France)

    2013-09-15

    The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition. - Highlights: • Oxygen tension level regulates viral replication in vitro and possibly in vivo. • Hypoxia-inducible factor 1 (HIF-1α) is the principal factor involved in Oxygen tension level. • HIF-1α upregulates gene expression for example of HIV, JC and Kaposi sarcoma viruses. • In addition to classical chemotherapy inhibition of HIF-1α may constitute a new track to treat human viral infections.

  20. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

    2000-01-01

    To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

  1. Investigating the tension load of rubber composites by impact ...

    Indian Academy of Sciences (India)

    An increase in the allowable stress when the belt is tensioned was examined during the test, to determine the effect of impact on the tension load. The obtained values of tension load are assessed using basic mathematical and statistical methods. Using the Design of Experiments method, factors that significantly affect the ...

  2. Tension-filled Governance?

    DEFF Research Database (Denmark)

    Celik, Tim Holst

    on the statesituated tension-filled functional relationship between legitimation and accumulation, the study both historically and theoretically reworks this approach and reapplies it for the post-1970s/1990s governance period. It asks whether and to what extent governance has served as a distinctive post- 1970s/1990s...... state-facilitated way of bridging/altering the tension-filled relationship between legitimation and fiscal accumulation in Western European liberal-capitalist democratic polities....

  3. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

    2000-01-01

    To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide.......To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

  4. Effects of a semi-infinite stratification on the Rayleigh-Taylor instability in an interface with surface tension

    Directory of Open Access Journals (Sweden)

    Ángel de Andrea González

    2017-09-01

    Full Text Available The Rayleigh-Taylor instability (RTI in an infinite slab where a constant density lower fluid is initially separated from an upper stratified fluid is discussed in linear regime. The upper fluid is of increasing exponential density and surface tension is considered between both of them. It was found useful to study stability by using the initial value problem approach (IVP, so that we ensure the inclusion of certain continuum modes, otherwise neglected. This methodology includes the branch cut in the complex plane, consequently, in addition to discrete modes (surface RTI modes, a set of continuum modes (internal RTI modes also appears. As a result, the usual information given by the normal mode method is now complete. Furthermore, a new role is found for surface tension: to transform surface RTI modes (discrete spectrum into internal RTI modes belonging to a continuous spectrum at a critical wavenumber. As a consequence, the cut-off wavenumber disappears: i.e. the growth rate of the RTI surface mode does not decay to zero at the cut-off wavenumber, as previous researchers used to believe. Finally, we found that, due to the continuum, the asymptotic behavior of the perturbation with respect to time is slower than the exponential when only the continuous spectrum exists.

  5. Effects of Thai traditional massage on pressure pain threshold and headache intensity in patients with chronic tension-type and migraine headaches.

    Science.gov (United States)

    Chatchawan, Uraiwan; Eungpinichpong, Wichai; Sooktho, Suparat; Tiamkao, Somsak; Yamauchi, Junichiro

    2014-06-01

    To investigate the effects of Thai traditional massage (TTM) on pressure pain threshold (PPT) and headache intensity in patients with chronic tension-type and migraine headaches. Randomized controlled trial of TTM compared with the sham ultrasound (nine sessions each) during a 3-week period. Seventy-two participants who had had a headache diagnosis for at least 3 months before the experiment was recruited. After the treatment and at 3 and 9 weeks of follow-up, the TTM group showed a significant increase in PPT (p0.05). TTM could increase PPT and reduce headache intensity, suggesting that this is a possible alternative treatment for chronic headaches.

  6. Effect of Ginkgo biloba on visual field and contrast sensitivity in Chinese patients with normal tension glaucoma: a randomized, crossover clinical trial.

    Science.gov (United States)

    Guo, Xinxing; Kong, Xiangbin; Huang, Rui; Jin, Ling; Ding, Xiaohu; He, Mingguang; Liu, Xing; Patel, Mehul Chimanlal; Congdon, Nathan G

    2014-01-07

    We evaluated the effect of ginkgo biloba extract on visual field defect and contrast sensitivity in a Chinese cohort with normal tension glaucoma. In this prospective, randomized, placebo-controlled crossover study, patients newly diagnosed with normal tension glaucoma, either in a tertiary glaucoma clinic (n = 5) or in a cohort undergoing routine general physical examinations in a primary care clinic (n = 30), underwent two 4-week phases of treatment, separated by a washout period of 8 weeks. Randomization determined whether ginkgo biloba extract (40 mg, 3 times per day) or placebo (identical-appearing tablets) was received first. Primary outcomes were change in contrast sensitivity and mean deviation on 24-2 SITA standard visual field testing, while secondary outcomes included IOP and self-reported adverse events. A total of 35 patients with mean age 63.7 (6.5) years were randomized to the ginkgo biloba extract-placebo (n = 18) or the placebo-ginkgo biloba extract (n = 17) sequence. A total of 28 patients (80.0%, 14 in each group) who completed testing did not differ at baseline in age, sex, visual field mean deviation, contrast sensitivity, IOP, or blood pressure. Changes in visual field and contrast sensitivity did not differ by treatment received or sequence (P > 0.2 for all). Power to have detected a difference in mean defect as large as previously reported was 80%. In contrast to some previous reports, ginkgo biloba extract treatment had no effect on mean defect or contrast sensitivity in this group of normal tension glaucoma patients. (http://www.chictr.org number, ChiCTR-TRC-08000724).

  7. Amrinone effects on electromechanical coupling and depolarization-induced automaticity in ventricular muscle of guinea pigs and ferrets.

    Science.gov (United States)

    Malécot, C O; Arlock, P; Katzung, B G

    1985-01-01

    The effects of the cardiotonic agent, amrinone (0.05-4 mM), on electrical and mechanical activities of ferret and guinea-pig papillary muscles were studied using current and voltage clamp (single sucrose gap) techniques. In current clamp studies, amrinone increased, in a dose-dependent manner, contractile force elicited by action potential in both species. Depolarization-induced automaticity was facilitated in ferret muscles at all maximum diastolic potentials between -70 and -15 mV. Facilitation of automaticity in guinea-pig muscles occurred only at potentials more negative than -35 mV and was suppressed at more positive potentials. Cimetidine (10 microM) partially reversed the effects of amrinone on automaticity in both species. In voltage clamp studies, amrinone increased the slow inward current. Steady-state outward current was increased in guinea-pig but not in ferret muscles. A dual effect of amrinone on tension was observed. Amrinone was found to increase phasic tension of ferret papillary muscles only for depolarizations lasting less than 250 to 300 msec. For longer depolarizations, amrinone decreased the phasic tension (in a dose-dependent manner), whereas the tonic tension was not modified. The decrease as well as the increase in tension was associated with an increase of the slow inward current. The results suggest that amrinone may be arrhythmogenic and may have an intracellular action at the sarcoplasmic reticulum level (partial inhibition) in addition to its action on the calcium current.

  8. Membrane tension and membrane fusion

    OpenAIRE

    Kozlov, Michael M.; Chernomordik, Leonid V.

    2015-01-01

    Diverse cell biological processes that involve shaping and remodeling of cell membranes are regulated by membrane lateral tension. Here we focus on the role of tension in driving membrane fusion. We discuss the physics of membrane tension, forces that can generate the tension in plasma membrane of a cell, and the hypothesis that tension powers expansion of membrane fusion pores in late stages of cell-to-cell and exocytotic fusion. We propose that fusion pore expansion can require unusually la...

  9. Radiation-induced cardiovascular effects

    Science.gov (United States)

    Tapio, Soile

    Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

  10. The Dynamic Surface Tension of Water.

    Science.gov (United States)

    Hauner, Ines M; Deblais, Antoine; Beattie, James K; Kellay, Hamid; Bonn, Daniel

    2017-04-06

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m -1 ) than under equilibrium conditions (∼72 mN m -1 ) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments.

  11. The Dynamic Surface Tension of Water

    Science.gov (United States)

    2017-01-01

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m–1) than under equilibrium conditions (∼72 mN m–1) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments. PMID:28301160

  12. Surface Tension of Spacetime

    Science.gov (United States)

    Perko, Howard

    2017-01-01

    Concepts from physical chemistry and more specifically surface tension are introduced to spacetime. Lagrangian equations of motion for membranes of curved spacetime manifold are derived. The equations of motion in spatial directions are dispersion equations and can be rearranged to Schrodinger's equation where Plank's constant is related to membrane elastic modulus. The equation of motion in the time-direction has two immediately recognizable solutions: electromagnetic waves and corpuscles. The corpuscular membrane solution can assume different genus depending on quantized amounts of surface energy. A metric tensor that relates empty flat spacetime to energetic curved spacetime is found that satisfies general relativity. Application of the surface tension to quantum electrodynamics and implications for quantum chromodynamics are discussed. Although much work remains, it is suggested that spacetime surface tension may provide a classical explanation that combines general relativity with field theories in quantum mechanics and atomic particle physics.

  13. Modeling of flow stress size effect based on variation of dislocation substructure in micro-tension of pure nickel

    Science.gov (United States)

    Wang, Chuanjie; Liu, Huan; Zhang, Ying; Chen, Gang; Li, Yujie; Zhang, Peng

    2017-12-01

    Micro-forming is one promising technology for manufacturing micro metal parts. However, the traditional metal-forming theories fail to analyze the plastic deformation behavior in micro-scale due to the size effect arising from the part geometry scaling down from macro-scale to micro-scale. To reveal the mechanism of plastic deformation behavior size effect in micro-scale, the geometrical parameters and the induced variation of microstructure by them need to be integrated in the developed constitutive models considering the free surface effect. In this research, the variations of dislocation cell diameter with original grain size, strain and location (surface grain or inner grain) are derived according the previous research data. Then the overall flow stress of the micro specimen is determined by employing the surface layer model and the relationship between dislocation cell diameter and the flow stress. This new developed constitutive model considers the original grain size, geometrical dimension and strain simultaneously. The flow stresses in micro-tensile tests of thin sheets are compared with calculated results using the developed constitutive model. The calculated and experimental results match well. Thus the validity of the developed constitutive model is verified.

  14. Twin stability in highly nanotwinned Cu under compression, torsion and tension

    DEFF Research Database (Denmark)

    Hodge, A.M.; Furnish, T.A.; Shute, C.J.

    2012-01-01

    Twin stability under four distinct mechanical loading states has been investigated for highly nanotwinned Cu containing parallel nanotwins 40 nm thick. Observed deformation-induced microstructural changes under tension, compression, tension–tension fatigue and torsion are qualitatively compared...

  15. Critical oxygen tension and the effect of hypoxia on the oxygen consumption of the striped catfish, Pangasius hypophthaimos (Pangasiidae)

    DEFF Research Database (Denmark)

    Lefevre, S.; Bayley, Mark; Wang, Tobias

    2008-01-01

    consumption (VO2), measured with intermittent closed respirometry, was 67.8 ± 5.1 mLO2/kg/h when the fish were maintained without access to air at 27 °C. The critical oxygen tension (Pcrit) at these conditions was 57.9 ± 8.9 mmHg (N = 7). The metabolic response to aquatic hypoxia was studied in fish subjected...... of studies to characterize oxygen consumption and the partitioning of gas exchange under a variety of environmental conditions. Contrary to early studies, we have shown that Pangasius is a facultative air-breather, with 100% survival after 7 days of forced submergence at 27 °C (N = 18). Resting oxygen...

  16. A simulation analysis of the combined effects of muscle strength and surgical tensioning on lateral pinch force following brachioradialis to flexor pollicis longus transfer.

    Science.gov (United States)

    Mogk, Jeremy P M; Johanson, M Elise; Hentz, Vincent R; Saul, Katherine R; Murray, Wendy M

    2011-02-24

    Biomechanical simulations of tendon transfers performed following tetraplegia suggest that surgical tensioning influences clinical outcomes. However, previous studies have focused on the biomechanical properties of only the transferred muscle. We developed simulations of the tetraplegic upper limb following transfer of the brachioradialis (BR) to the flexor pollicis longus (FPL) to examine the influence of residual upper limb strength on predictions of post-operative transferred muscle function. Our simulations included the transfer, ECRB, ECRL, the three heads of the triceps, brachialis, and both heads of the biceps. Simulations were integrated with experimental data, including EMG and joint posture data collected from five individuals with tetraplegia and BR-FPL tendon transfers during maximal lateral pinch force exertions. Given a measured co-activation pattern for the non-paralyzed muscles in the tetraplegic upper limb, we computed the highest activation for the transferred BR for which neither the elbow nor the wrist flexor moment was larger than the respective joint extensor moment. In this context, the effects of surgical tensioning were evaluated by comparing the resulting pinch force produced at different muscle strength levels, including patient-specific scaling. Our simulations suggest that extensor muscle weakness in the tetraplegic limb limits the potential to augment total pinch force through surgical tensioning. Incorporating patient-specific muscle volume, EMG activity, joint posture, and strength measurements generated simulation results that were comparable to experimental results. Our study suggests that scaling models to the population of interest facilitates accurate simulation of post-operative outcomes, and carries utility for guiding and developing rehabilitation training protocols. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. Dynamic surface tension of heat transfer additives suitable for use in steam condensers and absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Yong-Du [Department of Mechanical and Automotive Engineering, Kongju National University, Kongju, Chungnam, 314-701 (Korea); Kim, Kwang J.; Kennedy, John M. [Department of Mechanical Engineering, University of Nevada-Reno, MS 312, Reno, NV 89557 (United States)

    2010-03-15

    Additives are often effectively used in enhancing heat transfer by creating a surface tension gradient on the surface of a condensate film to induce Marangoni driven ''dropwise-like'' condensation. The objective of the current study is to use the Maximum Bubble Pressure Method (MBPM) to evaluate dynamic behavior of the surface tension of solutions of three different additives (2-ethoxy ethanol, isobutylamine, and 2-ethyl-1-hexanol) of varying concentrations with water. It was shown that the effects of 2-ethoxy ethanol on surface tension was primarily dependent on solute concentration and showed little dependence on time (i.e. surface age of bubble). While both isobutylamine and 2-ethyl-1-hexanol showed strong dependence on both concentration and time, the effects of the later were far more dramatic. The results for all solutions are presented as functions of concentration and time (i.e. surface age of bubble). (author)

  18. Short term effectiveness of neural sliders and neural tensioners as an adjunct to static stretching of hamstrings on knee extension angle in healthy individuals: A randomized controlled trial.

    Science.gov (United States)

    Sharma, Saurab; Balthillaya, Ganesh; Rao, Roopa; Mani, Ramakrishnan

    2016-01-01

    To investigate the added benefit of nerve-biased interventions over static stretching in hamstring flexibility and to compare the effectiveness of two types of nerve-biased interventions over a week. Three-arm assessor-blinded randomized controlled trial. University Laboratory. Sixty healthy individuals (mean age = 22 ± 2.4 years) with reduced hamstring flexibility were randomized to three groups who received static stretching and neurodynamic sliders (NS-SS); static stretching with neurodynamic tensioner (NT-SS) and static stretching (SS) alone. Knee extension angle (KEA) in degrees. Baseline characteristics including demographic, anthropomorphic and KEA between groups were comparable. A significant interaction was observed between group (intervention) and time, [F (2,114) = 3.595; p = 0.031]. Post-hoc pairwise comparisons analyses revealed significant differences at post-intervention measurement time point between NS-SS and SS (mean difference: -6.8; 95%CI = -12, -1.5; p = 0.011) and NT-SS and SS (mean difference: -11.6; 95%CI = -16.7, -6.3; p tensioners are both effective in increasing hamstring flexibility as an adjunct to static hamstring stretching when compared to static stretching alone. No neural mobilization technique proved to be superior over another. This clinical trial is registered in Clinical Trials Registry- India (CTRI) with registration number CTRI/2012/05/002619. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Tension-type headache

    DEFF Research Database (Denmark)

    Bendtsen, Lars; Jensen, Rigmor

    2009-01-01

    The substantial societal and individual burdens associated with tension-type headache (TTH) constitute a previously overlooked major public health issue. TTH is prevalent, affecting up to 78% of the general population, and 3% suffer from chronic TTH. Pericranial myofascial nociception probably...

  20. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    Kiilgaard, Jens Folke; Pedersen, D B; Eysteinsson, T

    2004-01-01

    The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta...

  1. Rein tension during canter

    NARCIS (Netherlands)

    Egenvall, Agneta; Eisersiö, Marie; Rhodin, Marie; van Weeren, P.R.|info:eu-repo/dai/nl/074628550; Roepstorff, Lars

    2015-01-01

    Riders generally use reins as a means for communication with the horse. At present, the signalling pattern is poorly understood. The aim of this study was to illustrate and analyse the rein tension patterns in a number of rider/horse combinations across a variety of exercises in the canter gait. Our

  2. Melt-Bubble Surface Tension in Hydrous Magmas and the Effects of Alkalinity, Temperature, and Water Content

    Science.gov (United States)

    Lewis, A. E.; Gardner, J. E.

    2009-12-01

    Understanding the kinetics and controls on bubble nucleation in hydrous magmas is of fundamental importance to understanding volcanic eruptions. Eruptive style, whether explosive or effusive, may in fact be intrinsically linked to the nature of the nucleation of bubbles in the melt. The most abundant dissolved volatile to form bubbles in magma is H2O. To first order, melt-bubble surface tension (σ) and the supersaturation (ΔP) of water in the melt govern the onset and rate of bubble nucleation, assuming homogenous nucleation. The sensitivity of σ and its ability to significantly impact when nucleation occurs and ΔP warrants closer investigation. From the limited published data gathered, we know that surface tension varies in response to changes in temperature, water content, and melt composition, but their full impact is poorly constrained. For our analysis of σ we focus on the impact of melt composition, and have begun by using a trachytic melt with similar SiO2 content yet elevated alkali contents in comparison to available dacitic melt data (Mangan and Sisson, 2005). We have approached the problem by subjecting the trachyte melt to several hydrothermal decompression experiments at a single water content. We first hydrated the melt at super-liquidus conditions (1050° C and 150 MPa) for 5 days. Fourier transform infrared spectroscopy reveal consistent dissolved water contents of 4.70 (± 0.07) wt.% H2O in all samples. Five decompressions have been executed at 900°C, from the initial pressure of 150 MPa to various lower final pressures corresponding to ΔP values ranging from 94 MPa to 114 MPa. All samples were nearly instantaneously decompressed to the final pressure and held for 60 seconds before being rapidly quenched. Preliminary results tentatively indicate a σ of 0.078 N/m for hydrous trachyte. This value correlates well with the dacitic data, although those experiments were not conducted isothermally, suggesting the greater proportion of alkalis

  3. Surface tension of spherical drops from surface of tension

    Energy Technology Data Exchange (ETDEWEB)

    Homman, A.-A.; Bourasseau, E. [CEA/DAM DIF, F-91297 Arpajon Cedex (France); Stoltz, G. [Université Paris-Est, CERMICS (ENPC), INRIA, F-77455 Marne-la-Vallée (France); Malfreyt, P. [Institut de Chimie de Clermont-Ferrand, Université Blaise Pascal, UMR CNRS 6296, ICCF, BP 10448, F-63000 Clermont-Ferrand (France); Strafella, L.; Ghoufi, A., E-mail: aziz.ghoufi@univ-rennes1.fr [Institut de Physique de Rennes, Université de Rennes 1 UMR 6251 CNRS, 263 avenue Général Leclerc, 35042 Rennes (France)

    2014-01-21

    The determination of surface tension of curved interfaces is a topic that raised many controversies during the last century. Explicit liquid-vapor interface modelling (ELVI) was unable up to now to reproduce interfacial behaviors in drops due to ambiguities in the mechanical definition of the surface tension. In this work, we propose a thermodynamic approach based on the location of surface of tension and its use in the Laplace equation to extract the surface tension of spherical interfaces from ELVI modelling.

  4. A review on applications of nanotechnology in the enhanced oil recovery part A: effects of nanoparticles on interfacial tension

    Science.gov (United States)

    Cheraghian, Goshtasp; Hendraningrat, Luky

    2016-01-01

    Chemical enhanced oil recovery is another strong growing technology with the potential of a step change innovation, which will help to secure future oil supply by turning resources into reserves. While Substantial amount of crude oil remains in the reservoir after primary and secondary production, conventional production methods give access to on average only one-third of original oil in place, the use of surfactants and polymers allows for recovery of up to another third of this oil. Chemical flooding is of increasing interest and importance due to high oil prices and the need to increase oil production. Research in nanotechnology in the petroleum industry is advancing rapidly and an enormous progress in the application of nanotechnology in this area is to be expected. Nanotechnology has the potential to profoundly change enhanced oil recovery and to improve mechanism of recovery. This paper, therefore, focuses on the reviews of the application of nano technology in chemical flooding process in oil recovery and reviews the application nano in the polymer and surfactant flooding on the interfacial tension process.

  5. Effect of tension-free vaginal tape and TVT-obturator on lower urinary tract symptoms other than stress urinary incontinence.

    Science.gov (United States)

    Ballert, Katie N; Kanofsky, Jamie A; Nitti, Victor W

    2008-03-01

    Variable effects on lower urinary tract symptoms (LUTS) other than stress urinary incontinence (SUI) have been reported after tension-free vaginal tape (TVT). We measured the effect of TVT on LUTS using the American Urological Association Symptom Index (AUASI). Patients undergoing TVT completed the AUASI pre- and post-operatively. Total scores (TS), storage scores (SS), and voiding scores (VS) were compared overall and among patients with SUI vs mixed urinary incontinence (MUI) and those who underwent TVT vs TVT-obturator (TVT-O). The mean change in TS and SS was -3.6 and -3.0. Mean reductions in TS and SS were significant in all patient subsets with no change in VS. There was no significant difference in the mean changes in TS between patients with SUI vs MUI or those undergoing TVT vs TVT-O. LUTS are improved after TVT in most patients. In general, voiding symptoms were not adversely affected.

  6. Surface Tension and Capillary Rise

    Science.gov (United States)

    Walton, Alan J.

    1972-01-01

    Discussion of the shortcomings of textbook explanations of surface tension, distinguishing between concepts of tension and capillary rise. The arguments require only a clear understanding of Newtonian mechanics, notably potential energy. (DF)

  7. Necessary Tension in Marine Risers Tension des colonnes montantes en mer

    Directory of Open Access Journals (Sweden)

    Lubinski A.

    2006-11-01

    Full Text Available The tension governing transverse static and dynamic deflections in a riser is not the actual tension but the so-called « effective tension » The concept of effective tension and effective compression is thoroughly explained, and means for calculating effective forces are given. Numerical examples are worked out for risers whose length is between 152 m (520 ft and 920 m (3020 ft. The reciprocal of maximum bending moment of the vicinity of the hall joint is plotted versus the effective tension of the ball joint. Bending moments used were obtained through use of static and dynamic computer programs applied ta a variety of conditions of wave loading, use or non-use of buoyant moterial sleeves, etc. The most important parameters affecting riser performance are the effective La tension régissant les déflections transversales statiques et dynamiques d'une colonne montante n'est pas la tension réelle mais ce qu'on appelle « la tension effective ». Le concept de tension ou de compression effective est expliqué en détail et la façon de calculer les forces effectives est indiquée dans cet article. Des exemples numériques sont développés pour des colonnes montantes de longueur comprise entre 152 m (520 ft et 920 m (3 020 ft. On a tracé la courbe de l'inverse du moment fléchissant en fonction de la tension effective à l'articulation. Les moments fléchissants utilisés ont été calculés par ordinateur en utilisant des programmes dynamiques et statiques pour des conditions variées d'action des vagues, la colonne montante étant ou non munie de manchettes de flottabilité, etc. Les deux paramètres les plus importants qui affectent le bon comportement d'une colonne montante sont la tension effective et la charge latérale.

  8. The effects of cervical traction, cranial rhythmic impulse, and Mckenzie exercise on headache and cervical muscle stiffness in episodic tension-type headache patients.

    Science.gov (United States)

    Choi, Sung-Yong; Choi, Jung-Hyun

    2016-03-01

    [Purpose] The purpose of this study was to examine the effects of cervical traction treatment, cranial rhythmic impulse treatment, a manual therapy, and McKenzie exercise, a dynamic strengthening exercise, on patients who have the neck muscle stiffness of the infrequent episodic tension-type (IETTH) headache and frequent episodic tension-type headache(FETTH), as well as to provide the basic materials for clinical interventions. [Subjects] Twenty-seven subjects (males: 15, females: 12) who were diagnosed with IETTH and FETTH after treatment by a neurologist were divided into three groups: (a cervical traction group (CTG, n=9), a cranial rhythmic contractiongroup (CRIG, n=9), and a McKenzie exercise group (MEG, n=9). An intervention was conducted for each group and the differences in their degrees of neck pain and changes in muscle tone were observed. [Results] In the within-group comparison of each group, headache significantly decreased in CTG. According to the results of the analysis of the muscle tone of the upper trapezius, there was a statistically significant difference in MEG on the right side and in CRIG on the left side. According to the results of the analysis of the muscle tone of the sternocleidomastoid muscle, there was a statistically significant difference in MEG on the right side and in CRIG on the left side. [Conclusion] In the comparison of the splenius capitis muscle between the groups, there was a statistically significant difference on the right side. Hence, compared to the other methods, cervical traction is concluded to be more effective at reducing headaches in IETTH and FETTH patients.

  9. The effects of aerobic exercise for persons with migraine and co-existing tension-type headache and neck pain. A randomized, controlled, clinical trial

    DEFF Research Database (Denmark)

    Krøll, Lotte Skytte; Hammarlund, Catharina Sjödahl; Linde, Mattias

    2018-01-01

    Aim To evaluate aerobic exercise in migraine and co-existing tension-type headache and neck pain. Methods Consecutively recruited persons with migraine and co-existing tension-type headache and neck pain were randomized into an exercise group or control group. Aerobic exercise consisted of bike/c...

  10. Fatigue in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben

    1999-01-01

    Traditinally fatigue resistance is quantified as number of cycles to failure at a given stress level. A previous study by the authors showed that fatigue in compression parallel to the grain is governed partly by duration of load and partly by an effect of loading, i.e. a combination of a creep...... and on dowel type joints with slotted in steel plates. In series of ten, the small specimens are taken to fatigue failure in uniform tension at square wave shaped load cycles at 0.01 Hz and 0.1 Hz. In order to test the predictive validity of the result from the small tension specimens, fatigue experiments...... mechanism and a mechanism connected to damage introduce in the loading sequences. The purpose of the present study is to disentangle the effect of duration of load from the effect of load oscillation in fatigue in tension perpendicular to the grain. Fatigue experiments are made on small specimens...

  11. Fatigue In Tension Perpendicular to the Grain

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Uhre; Hoffmeyer, Preben

    2004-01-01

    Traditionally fatigue resistance is quantified as number of cycles to failure at a given stress level. A previous study by the authors showed that fatigue in compression parallel to the grain is governed partly by duration of load and partly by an effect of loading, i.e. a combination of a creep...... and on dowel type joints with slotted in steel plates. In series of ten, the small specimens are taken to fatigue failure in uniform tension at square wave shaped load cycles at 0.01 Hz and 0.1 Hz. In arder to test the predictive validity of the result from the small tension specimens, fatigue experiments...... mechanism and a mechanism connected to damage introduced in the loading sequences. The purpose of the present study is to disentangle the effect of duration of load from the effect of load oscillation in fatigue in tension perpendicular to the grain. Fatigue experiments are made on small specimens...

  12. Cable tensioned membrane solar collector module with variable tension control

    Science.gov (United States)

    Murphy, Lawrence M.

    1985-01-01

    Disclosed is a solar collector comprising a membrane for concentrating sunlight, a plurality of elongated structural members for suspending the membrane member thereon, and a plurality of control members for adjustably tensioning the membrane member, as well as for controlling a focus produced by the membrane members. Each control member is disposed at a different corresponding one of the plurality of structural members. The collector also comprises an elongated flexible tensioning member, which serves to stretch the membrane member and to thereafter hold it in tension, and a plurality of sleeve members, which serve to provide the membrane member with a desired surface contour during tensioning of the membrane member. The tensioning member is coupled to the structural members such that the tensioning member is adjustably tensioned through the structural members. The tensioning member is also coupled to the membrane member through the sleeve members such that the sleeve members uniformly and symmetrically stretch the membrane member upon applying tension to the tensioning member with the control members.

  13. Effectiveness of manual therapy compared to usual care by the general practitioner for chronic tension-type headache: design of a randomised clinical trial

    Directory of Open Access Journals (Sweden)

    Dekker Joost

    2009-02-01

    Full Text Available Abstract Background Patients with Chronic Tension Type Headache (CTTH report functional and emotional impairments (loss of workdays, sleep disturbances, emotional well-being and are at risk for overuse of medication. Manual therapy may improve symptoms through mobilisation of the spine, correction of posture, and training of cervical muscles. We present the design of a randomised clinical trial (RCT evaluating the effectiveness of manual therapy (MT compared to usual care by the general practitioner (GP in patients with CTTH. Methods and design Patients are eligible for participation if they present in general practice with CTTH according to the classification of the International Headache Society (IHS. Participants are randomised to either usual GP care according to the national Dutch general practice guidelines for headache, or manual therapy, consisting of mobilisations (high- and low velocity techniques, exercise therapy for the cervical and thoracic spine and postural correction. The primary outcome measures are the number of headache days and use of medication. Secondary outcome measures are severity of headache, functional status, sickness absence, use of other healthcare resources, active cervical range of motion, algometry, endurance of the neckflexor muscles and head posture. Follow-up assessments are conducted after 8 and 26 weeks. Discussion This is a pragmatic trial in which interventions are offered as they are carried out in everyday practice. This increases generalisability of results, but blinding of patients, GPs and therapists is not possible. The results of this trial will contribute to clinical decision making of the GP regarding referral to manual therapy in patients with chronic tension headache.

  14. Effects of xylazine on acid-base balance and arterial blood-gas tensions in goats under different environmental temperature and humidity conditions

    Directory of Open Access Journals (Sweden)

    E.G.M. Mogoa

    2000-07-01

    Full Text Available The effects of acute exposure to 3 different temperature and humidity conditions on arterial blood-gas and acid-base balance in goats were investigated after intravenous bolus administration of xylazine at a dose of 0.1 mg/kg. Significant (P < 0.05 changes in the variables occurred under all 3 environmental conditions. Decreases in pH, partial pressure of oxygen and oxyhaemoglobin saturation were observed, and the minimum values for oxygen tension and oxyhaemoglobin saturation were observed within 5 min of xylazine administration. The pH decreased to its minimum values between 5 and 15 min. Thereafter, the variables started to return towards baseline, but did not reach baseline values at the end of the 60 min observation period. Increases in the partial pressure of carbon dioxide, total carbon dioxide content, bicarbonate ion concentration, and the actual base excess were observed. The maximum increase in the carbon dioxide tension occurred within 5 min of xylazine administration. The increase in the actual base excess only became significant after 30 min in all 3 environments, and maximal increases were observed at 60 min. There were no significant differences between the variables in the 3 different environments. It was concluded that intravenous xylazine administration in goats resulted in significant changes in arterial blood-gas and acid-base balance that were associated with hypoxaemia and respiratory acidosis, followed by metabolic alkalosis that continued for the duration of the observation period. Acute exposure to different environmental temperature and humidity conditions after xylazine administration did not influence the changes in arterial blood-gas and acid-base balance.

  15. Estimation of solid-liquid interfacial tension using curved surface of a soft solid.

    Science.gov (United States)

    Mondal, Subrata; Phukan, Monmee; Ghatak, Animangsu

    2015-10-13

    Unlike liquids, for crystalline solids the surface tension is known to be different from the surface energy. However, the same cannot be said conclusively for amorphous materials like soft cross-linked elastomers. To resolve this issue we have introduced here a direct method for measuring solid-liquid interfacial tension by using the curved surface of a solid. In essence, we have used the inner surface of tiny cylindrical channels embedded inside a soft elastomeric film for sensing the effect of the interfacial tension. When a liquid is inserted into the channel, because of wetting-induced alteration in interfacial tension, its thin wall deflects considerably; the deflection is measured with an optical profilometer and analyzed using the Föppl-von Kármán equation. We have used several liquids and cross-linked poly(dimethylsiloxane) as the solid to show that the estimated values of the solid-liquid interfacial tension matches with the corresponding solid-liquid interfacial energy reasonably well.

  16. Radiation Induced Bystander Effect in vivo

    OpenAIRE

    Chai, Yunfei; Hei K. Tom

    2009-01-01

    Radiation-induced bystander effect is defined as the induction of biological effects in cells that are not directly traversed by radiation, but merely in the presence of cells that are. Although radiation induced bystander effects have been well defined in a variety of in vitro models using a range of endpoints including clonogenic survival, mutations, neoplastic transformation, apoptosis, micronucleus, chromosomal aberrations and DNA double strand breaks, the mechanism(s) as well as the pres...

  17. Societal costs in displaced transverse olecranon fractures: using decision analysis tools to find the most cost-effective strategy between tension band wiring and locked plating.

    Science.gov (United States)

    Francis, Tittu; Washington, Travis; Srivastava, Karan; Moutzouros, Vasilios; Makhni, Eric C; Hakeos, William

    2017-11-01

    Tension band wiring (TBW) and locked plating are common treatment options for Mayo IIA olecranon fractures. Clinical trials have shown excellent functional outcomes with both techniques. Although TBW implants are significantly less expensive than a locked olecranon plate, TBW often requires an additional operation for implant removal. To choose the most cost-effective treatment strategy, surgeons must understand how implant costs and return to the operating room influence the most cost-effective strategy. This cost-effective analysis study explored the optimal treatment strategies by using decision analysis tools. An expected-value decision tree was constructed to estimate costs based on the 2 implant choices. Values for critical variables, such as implant removal rate, were obtained from the literature. A Monte Carlo simulation consisting of 100,000 trials was used to incorporate variability in medical costs and implant removal rates. Sensitivity analysis and strategy tables were used to show how different variables influence the most cost-effective strategy. TBW was the most cost-effective strategy, with a cost savings of approximately $1300. TBW was also the dominant strategy by being the most cost-effective solution in 63% of the Monte Carlo trials. Sensitivity analysis identified implant costs for plate fixation and surgical costs for implant removal as the most sensitive parameters influencing the cost-effective strategy. Strategy tables showed the most cost-effective solution as 2 parameters vary simultaneously. TBW is the most cost-effective strategy in treating Mayo IIA olecranon fractures despite a higher rate of return to the operating room. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  18. A microprocessor based portable bolt tension monitor

    Science.gov (United States)

    Perey, D. F.

    1991-01-01

    A bolt tension monitor (BTM) which uses ultrasonics and a pulsed phase locked loop circuit to measure load-induced acoustic phase shifts which are independent of friction is described. The BTM makes it possible to measure the load in a bolt that was tightened at some time in the past. This capability to recertify a load after-the-fact will help to insure the integrity of a bolted joint.

  19. Effect of overloading on fatigue performance of reinforced concrete beams strengthened with externally post-tensioned carbon-fibre-reinforced polymer tendons

    National Research Council Canada - National Science Library

    Elrefai, Ahmed; West, Jeffrey S; Soudki, Khaled A

    2008-01-01

    This paper presents the results of an experimental and analytical study of the fatigue performance of reinforced concrete beams strengthened with externally post-tensioned carbon-fibre-reinforced polymer (CFRP) tendons...

  20. A continuum method for modeling surface tension

    Science.gov (United States)

    Brackbill, J. U.; Kothe, D. B.; Zemach, C.

    1992-01-01

    In the novel method presented for modeling the effects of surface tension on fluid motion, the interfaces between fluids with different, color-represented properties are finite-thickness transition regions across which the color varies continuously. A force density proportional to the surface curvature of constant color is defined at each point in the transition region; this force-density is normalized in such a way that the conventional description of surface tension on an interface is recovered when the ratio of local transition-reion thickness to local curvature radius approaches zero. The properties of the method are illustrated by computational results for 2D flows.

  1. Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

    DEFF Research Database (Denmark)

    Jensen, Pia; Gramsbergen, Jan-Bert; Zimmer, Jens

    2011-01-01

    Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation o...

  2. Static tensioning promotes hamstring tendons force relaxation more reliably than cycling tensioning.

    Science.gov (United States)

    Piedade, Sérgio Rocha; Dal Fabbro, Inácio Maria; Mischan, Martha Maria; Piedade, Cezar; Maffulli, Nicola

    2017-08-01

    Graft elongation might be a major reason for increased anterior laxity after anterior cruciate ligament (ACL) reconstruction. This study analyzed the force relaxation values and their stabilization when single strands of the gracilis and semitendinosus tendons underwent cyclic and static tensioning at 2.5% strain level, and compared the efficiency of static and cyclic tensioning in promoting force relaxation. Eighteen gracilis tendons and 18 semitendinosus tendons from nine male cadavers (mean age: 22.44years) were subjected to 10 in vitro cyclic loads at 2.5% strain level, or to a static load at 2.5% strain level. During cyclic loading, the reduction in force values tended to stabilize after the sixth cyclic load, while, in the case of static loading, this stabilization occurred by the second minute. Comparing static and cyclic loading, the gracilis tendon had similar mechanical responses in both conditions, while the semitendinosus tendon showed greater force relaxation in static compared with cyclic loading. Considering that the semitendinosus tendon is the main component of the hamstring graft, its biomechanical response to loading should guide the tensioning protocol. Therefore, static tensioning seems more effective for promoting force relaxation of the semitendinosus tendon than cyclic tensioning. The gracilis tendon showed a similar mechanical response to either tensioning protocols. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Holding the Tension.

    Science.gov (United States)

    Feudtner, Chris

    2016-05-01

    My colleagues and I had been asked by a member of a clinical team to help sort through the ethics of stopping a life-sustaining intervention for a very ill child. We had already talked with the parents, the physicians, and the folks from nursing, social work, and chaplaincy. Terms like "suffering," "cruel," "compassion," and "moral distress" had been uttered, as had terms like "inappropriate," "unethical," "neglectful," and "risk-management." The group had now stuffed all of these polarizing thoughts and feelings into this cramped room with only one door. And everyone was looking at me. What skill, competency, or inner capacity must one possess to hold and manage such tension? © 2016 The Hastings Center.

  4. Changes of blood flow, oxygen tension, action potential and vascular permeability induced by arterial ischemia or venous congestion on the spinal cord in canine model

    National Research Council Canada - National Science Library

    Kobayashi, Shigeru; Yoshizawa, Hidezo; Shimada, Seiichiro; Guerrero, Alexander Rodríguez; Miyachi, Masaya

    2013-01-01

    ... disturbance induced by venous congestion is not fully understood. Since Kadyi's first description of the venous system of the spinal cord, there have been few other studies on the subject. 3 Regarding the intramedullary vascular system, the central part of the spinal cord is supplied unilaterally by branches from the central artery enteri...

  5. Maintenance of Smoking Cessation: Effect of Follow-Up Letters, Smoking Motivation, Muscle Tension, and Health Locus of Control.

    Science.gov (United States)

    Shipley, Robert H.

    1981-01-01

    Following smoking-cessation treatment, half of 44 subjects were sent supportive maintenance letters. Letters produced no main effect but reduced smoking in subjects who smoked from habit or received little pleasure from smoking. Letters increased smoking among opposite subject groups and those believing powerful others could not influence their…

  6. The effect of plate thickness, surface tension and fluid flow on detachment of drops from a plate

    NARCIS (Netherlands)

    Lexmond, A.S.; Geld, C.W.M. van der

    2005-01-01

    The pinch-off of drops from the downstream end of plates is an important re-entrainment mechanism of condensate in compact condensers. The present experimental study complements a previous one [A.S. Lexmond, C.W.M. van der Geld, The effect of fluid flow on detachment of drops from the downstream end

  7. Hygroscopic properties of Amazonian biomass burning and European background HULIS and investigation of their effects on surface tension with two models linking H-TDMA to CCNC data

    Directory of Open Access Journals (Sweden)

    E. O. Fors

    2010-06-01

    Full Text Available HUmic-LIke Substances (HULIS have been identified as major contributors to the organic carbon in atmospheric aerosol. The term "HULIS" is used to describe the organic material found in aerosol particles that resembles the humic organic material in rivers and sea water and in soils. In this study, two sets of filter samples from atmospheric aerosols were collected at different sites. One set of samples was collected at the K-puszta rural site in Hungary, about 80 km SE of Budapest, and a second was collected at a site in Rondônia, Amazonia, Brazil, during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC biomass burning season experiment. HULIS were extracted from the samples and their hygroscopic properties were studied using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA at relative humidity (RH <100%, and a cloud condensation nucleus counter (CCNC at RH >100%. The H-TDMA measurements were carried out at a dry diameter of 100 nm and for RH ranging from 30 to 98%. At 90% RH the HULIS samples showed diameter growth factors between 1.04 and 1.07, reaching values of 1.4 at 98% RH. The cloud nucleating properties of the two sets of aerosol samples were analysed using two types of thermal static cloud condensation nucleus counters. Two different parameterization models were applied to investigate the potential effect of HULIS surface activity, both yielding similar results. For the K-puszta winter HULIS sample, the surface tension at the point of activation was estimated to be lowered by between 34% (47.7 mN/m and 31% (50.3 mN/m for dry sizes between 50 and 120 nm in comparison to pure water. A moderate lowering was also observed for the entire water soluble aerosol sample, including both organic and inorganic compounds, where the surface tension was decreased by between 2% (71.2 mN/m and 13% (63.3 mN/m.

  8. Effects of Low and High Oxygen Tensions and Related Respiratory Conditions on Visual Performance: A Literature Review

    Science.gov (United States)

    1988-07-01

    Chapter 14: "Intraocular oxygen"). This oxygen is used in the eye to prevent depolarization of neurons (operate the Na/K pump) and to maintain synaptic...different species. In the rabbit, cat, and man the site was determined to be neurons of the ganglionic cell layer. Early processes of retinal excitation were...1983) used the technique of laser Doppler velocimetry to study the effect of pure oxIgen breathing on retinal blood flow in normal human subjects

  9. Effects of toughness anisotropy and combined tension, torsion, and bending loads on fracture behavior of ferritic nuclear pipe

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, R.; Marshall, C.; Ghadiali, N.; Wilkowski, G. [Battelle, Columbus, OH (United States)

    1997-04-01

    This paper summarizes work on angled through-wall-crack initiation and combined loading effects on ferritic nuclear pipe performed as part of the Nuclear Regulatory Commission`s research program entitled {open_quotes}Short Cracks In Piping an Piping Welds{close_quotes}. The reader is referred to Reference 1 for details of the experiments and analyses conducted as part of this program. The major impetus for this work stemmed from the observation that initially circumferentially oriented cracks in carbon steel pipes exhibited a high tendency to grow at a different angle when the cracked pipes were subjected to bending or bending plus pressure loads. This failure mode was little understood, and the effect of angled crack grown from an initially circumferential crack raised questions about how cracks in a piping system subjected to combined loading with torsional stresses would behave. There were three major efforts undertaken in this study. The first involved a literature review to assess the causes of toughness anisotropy in ferritic pipes and to develop strength and toughness data as a function of angle from the circumferential plane. The second effort was an attempt to develop a screening criterion based on toughness anisotropy and to compare this screening criterion with experimental pipe fracture data. The third and more significant effort involved finite element analyses to examine why cracks grow at an angle and what is the effect of combined loads with torsional stresses on a circumferentially cracked pipe. These three efforts are summarized.

  10. Effect on intraocular pressure of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in patients with normal-tension glaucoma.

    Science.gov (United States)

    Igarashi, Ryoko; Togano, Tetsuya; Sakaue, Yuta; Yoshino, Takaiko; Ueda, Jun; Fukuchi, Takeo

    2014-01-01

    Purpose. To evaluate the effect on intraocular pressure (IOP) of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in Japanese patients with normal-tension glaucoma (NTG). Methods. 27 NTG patients (54 eyes) were compared IOP, superficial punctuate keratitis (SPK) scores, and conjunctival injection scores in eyes treated with prostaglandin (PG) or PG analog/beta-blocker (PG/b) fixed-combination 6 months after the change in therapy. Results. The mean baseline intraocular pressure was 17.4 ± 1.59 mmHg in eyes receiving PG therapy only and 17.4 ± 1.69 mmHg in eyes switched to PG/b. Switching to fixed combination therapy from PG monotherapy, the mean IOP was 13.1 ± 1.79 mmHg (P < 0.001)  (-24.71% reduction from baseline) at 6 months. The mean conjunctival injection score was 0.69 for eyes on PG monotherapy and 0.56 for eyes on fixed combination therapy (P = 0.028). The mean SPK scores were 0.46 and 0.53. This difference was not statistically significant (P = 0.463). Conclusions. Switching from PG monotherapy to PG/b fixed combination therapy for NTG resulted in a greater intraocular pressure reduction than PG alone without increasing the number of instillations.

  11. Effect on Intraocular Pressure of Switching from Latanoprost and Travoprost Monotherapy to Timolol Fixed Combinations in Patients with Normal-Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ryoko Igarashi

    2014-01-01

    Full Text Available Purpose. To evaluate the effect on intraocular pressure (IOP of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in Japanese patients with normal-tension glaucoma (NTG. Methods. 27 NTG patients (54 eyes were compared IOP, superficial punctuate keratitis (SPK scores, and conjunctival injection scores in eyes treated with prostaglandin (PG or PG analog/beta-blocker (PG/b fixed-combination 6 months after the change in therapy. Results. The mean baseline intraocular pressure was 17.4±1.59 mmHg in eyes receiving PG therapy only and 17.4±1.69 mmHg in eyes switched to PG/b. Switching to fixed combination therapy from PG monotherapy, the mean IOP was 13.1±1.79 mmHg (P<0.001  (-24.71% reduction from baseline at 6 months. The mean conjunctival injection score was 0.69 for eyes on PG monotherapy and 0.56 for eyes on fixed combination therapy (P=0.028. The mean SPK scores were 0.46 and 0.53. This difference was not statistically significant (P=0.463. Conclusions. Switching from PG monotherapy to PG/b fixed combination therapy for NTG resulted in a greater intraocular pressure reduction than PG alone without increasing the number of instillations.

  12. Comparison of Effectiveness between Tension-Free Vaginal Tape (TVT) and Trans-Obturator Tape (TOT) in Patients with Stress Urinary Incontinence and Intrinsic Sphincter Deficiency.

    Science.gov (United States)

    Kim, Hyeong Gon; Park, Hyoung Keun; Paick, Sung Hyun; Choi, Woo Suk

    2016-01-01

    The aim of this study was to compare the two types of mid-urethral slings for stress urinary incontinence (SUI) with intrinsic sphincter deficiency (ISD). This retrospective study included patients who underwent tension-free vaginal tape (TVT) procedure or transobturator tape (TOT) procedure by a single surgeon for SUI with ISD, defined as Valsalva leak point pressure (VLPP) TVT and 52 patients received TOT. Age, underlying diseases, Stamey grade, cystocele grade, and presence of urge incontinence were not significantly different between the two groups. Urodynamic parameters including maximal urethral closing pressure, detrusor overactivity, VLPP, urethral hypermobility (Q-tip ≥ 30°), were also comparable between the two groups. Success rate was significantly higher in the TVT group than in the TOT group (95.2% vs. 82.7%, p = 0.009). On multivariate analysis, only TOT surgery (OR = 3.922, 95%CI = 1.223-12.582, p = 0.022) was a risk factor for failure following surgical treatment. TVT is more effective than TOT in treatment of female SUI with ISD.

  13. A Randomized Controlled Trial on the Effectiveness of Court-Type Traditional Thai Massage versus Amitriptyline in Patients with Chronic Tension-Type Headache.

    Science.gov (United States)

    Damapong, Peerada; Kanchanakhan, Naowarat; Eungpinichpong, Wichai; Putthapitak, Prasobsook; Damapong, Pongmada

    2015-01-01

    This study aimed to evaluate the effectiveness of the court-type traditional Thai massage (CTTM) to treat patients with chronic tension-type headaches (CTTHs) comparing with amitriptyline taking. A randomized controlled trial was conducted. Sixty patients diagnosed with CTTH were equally divided into a treatment and a control group. The treatment group received a 45-minute course of CTTM twice per week lasting 4 weeks while the control group was prescribed 25 mg of amitriptyline once a day before bedtime lasting 4 weeks. Outcome measures were evaluated in week 2, week 4 and followed up in week 6 consisting of visual analog scale (VAS), tissue hardness, pressure pain threshold (PPT), and heart rate variability (HRV). The results demonstrated a significant decrease in VAS pain intensity for the CTTM group at different assessment time points while a significant difference occurred in within-group and between-group comparison (P < 0.05) for each evaluated measure. Moreover, the tissue hardness of the CTTM group was significantly lower than the control group at week 4 (P < 0.05). The PPT and HRV of the CTTM group were significantly increased (P < 0.05). CTTM could be an alternative therapy for treatment of patients with CTTHs.

  14. A Randomized Controlled Trial on the Effectiveness of Court-Type Traditional Thai Massage versus Amitriptyline in Patients with Chronic Tension-Type Headache

    Directory of Open Access Journals (Sweden)

    Peerada Damapong

    2015-01-01

    Full Text Available This study aimed to evaluate the effectiveness of the court-type traditional Thai massage (CTTM to treat patients with chronic tension-type headaches (CTTHs comparing with amitriptyline taking. A randomized controlled trial was conducted. Sixty patients diagnosed with CTTH were equally divided into a treatment and a control group. The treatment group received a 45-minute course of CTTM twice per week lasting 4 weeks while the control group was prescribed 25 mg of amitriptyline once a day before bedtime lasting 4 weeks. Outcome measures were evaluated in week 2, week 4 and followed up in week 6 consisting of visual analog scale (VAS, tissue hardness, pressure pain threshold (PPT, and heart rate variability (HRV. The results demonstrated a significant decrease in VAS pain intensity for the CTTM group at different assessment time points while a significant difference occurred in within-group and between-group comparison (P < 0.05 for each evaluated measure. Moreover, the tissue hardness of the CTTM group was significantly lower than the control group at week 4 (P < 0.05. The PPT and HRV of the CTTM group were significantly increased (P < 0.05. CTTM could be an alternative therapy for treatment of patients with CTTHs.

  15. Comparison of Effectiveness between Tension-Free Vaginal Tape (TVT and Trans-Obturator Tape (TOT in Patients with Stress Urinary Incontinence and Intrinsic Sphincter Deficiency.

    Directory of Open Access Journals (Sweden)

    Hyeong Gon Kim

    Full Text Available The aim of this study was to compare the two types of mid-urethral slings for stress urinary incontinence (SUI with intrinsic sphincter deficiency (ISD.This retrospective study included patients who underwent tension-free vaginal tape (TVT procedure or transobturator tape (TOT procedure by a single surgeon for SUI with ISD, defined as Valsalva leak point pressure (VLPP < 60 cmH2O in a urodynamic study. Cases of neurogenic bladder, previous SUI surgery, and concomitant cystocele repair were excluded. The primary outcome was treatment success at 12 months, defined by self-reported absence of symptoms, no leakage episodes recorded, and no retreatment.Among the 157 women who were included in the final analysis, 105 patients received TVT and 52 patients received TOT. Age, underlying diseases, Stamey grade, cystocele grade, and presence of urge incontinence were not significantly different between the two groups. Urodynamic parameters including maximal urethral closing pressure, detrusor overactivity, VLPP, urethral hypermobility (Q-tip ≥ 30°, were also comparable between the two groups. Success rate was significantly higher in the TVT group than in the TOT group (95.2% vs. 82.7%, p = 0.009. On multivariate analysis, only TOT surgery (OR = 3.922, 95%CI = 1.223-12.582, p = 0.022 was a risk factor for failure following surgical treatment.TVT is more effective than TOT in treatment of female SUI with ISD.

  16. Effect of the emotional freedom technique on perceived stress, quality of life, and cortisol salivary levels in tension-type headache sufferers: a randomized controlled trial.

    Science.gov (United States)

    Bougea, Anastasia M; Spandideas, Nick; Alexopoulos, Evangelos C; Thomaides, Thomas; Chrousos, George P; Darviri, Christina

    2013-01-01

    To evaluate the short-term effects of the emotional freedom technique (EFT) on tension-type headache (TTH) sufferers. We used a parallel-group design, with participants randomly assigned to the emotional freedom intervention (n = 19) or a control arm (standard care n = 16). The study was conducted at the outpatient Headache Clinic at the Korgialenio Benakio Hospital of Athens. Thirty-five patients meeting criteria for frequent TTH according to International Headache Society guidelines were enrolled. Participants were instructed to use the EFT method twice a day for two months. Study measures included the Perceived Stress Scale, the Multidimensional Health Locus of Control Scale, and the Short-Form questionnaire-36. Salivary cortisol levels and the frequency and intensity of headache episodes were also assessed. Within the treatment arm, perceived stress, scores for all Short-Form questionnaire-36 subscales, and the frequency and intensity of the headache episodes were all significantly reduced. No differences in cortisol levels were found in any group before and after the intervention. EFT was reported to benefit patients with TTH. This randomized controlled trial shows promising results for not only the frequency and severity of headaches but also other lifestyle parameters. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Do manual therapy techniques have a positive effect on quality of life in people with tension-type headache? A randomized controlled trial.

    Science.gov (United States)

    Espí-López, Gemma V; Rodríguez-Blanco, Cleofás; Oliva-Pascual-Vaca, Angel; Molina-Martínez, Francisco; Falla, Deborah

    2016-08-01

    Controversy exists regarding the effectiveness of manual therapy for the relief of tension-type headache (TTH). However most studies have addressed the impact of therapy on the frequency and intensity of pain. No studies have evaluated the potentially significant effect on the patient's quality of life. To assess the quality of life of patients suffering from TTH treated for 4 weeks with different manual therapy techniques. Factorial, randomized, single-blinded, controlled clinical trial. Specialized center for the treatment of headache. Seventy-six (62 women) patients aged between 18 and 65 years (age: 39.9±10.9) with either episodic or chronic TTH. Patients were divided into four groups: suboccipital inhibitory pressure; suboccipital spinal manipulation; a combination of the two treatments; control. Quality of life was assessed using the SF-12 questionnaire (considering both the overall score and the different dimensions) at the beginning and end of treatment, and after a one month follow-up. Compared to baseline, the suboccipital inhibition treatment group showed a significant improvement in their overall quality of life at the one month follow-up and also showed specific improvement in the dimensions related to moderate physical activities, and in their emotional role. All the treatment groups, but not the control group, showed improvements in their physical role, bodily pain, and social functioning at the one month follow-up. Post treatment and at the one month follow-up, the combined treatment group showed improved vitality and the two treatment groups that involved manipulation showed improved mental health. All three treatments were effective at changing different dimensions of quality of life, but the combined treatment showed the most change. The results support the effectiveness of treatments applied to the suboccipital region for patients with TTH. Manual therapy techniques applied to the suboccipital region, for as little as four weeks, offered a

  18. Análise tensional e morfológica da anastomose colônica na colite induzida por ácido acético a 10%, em ratos Wistar, tratados com extrato aquoso de aroeira-do-sertão a 10% (Myracrodruon urundeuva fr. all. Tensional and morphologic analysis of the colonic anastomosis on 10% acetic acid induced colitis, in Wistar rats, treated with 10% aroeira-do-sertão (Myracrodruon urundeuva fr. all. aqueous extract

    Directory of Open Access Journals (Sweden)

    Antonio Rubens Soares Martins Cavalcante

    2005-04-01

    Full Text Available OBJETIVO: Verificar, do ponto de vista tensional e morfológico, o efeito do extrato aquoso de aroeira-do-sertão a 10% na anastomose colônica, na vigência de colite induzida por ácido acético a 10%, em ratos Wistar. MÉTODOS: Foram utilizados 48 ratos da linhagem Wistar, distribuídos em dois grupos. Todos os animais foram submetidos à indução da colite por solução aquosa de ácido acético a 10%. Vinte e quatro horas após, os animais foram submetidos à laparotomia, colotomia transversa total e anastomose término-terminal com fio de polipropileno 5-0. Grupo A (veículo, animais tratados com veículo à base de carboximetilcelulose. Grupo B (aroeira, animais tratados com extrato aquoso de aroeira a 10%. Ambos tratamentos foram sob a forma de enema. Os grupos A e B foram distribuídos em subgrupos A3, A7, A14 e A21; B3, B7, B14 e B21, respectivamente, conforme a data prevista para a eutanásia (3, 7, 14 e 21 dias. Nas respectivas datas, os animais foram relaparotomizados, o segmento colônico contendo a anastomose foi ressecado, submetido ao teste de pressão e em seguida à análise histológica. Para o estudo morfológico, as lâminas foram coradas com hematoxilina-eosina e avaliou-se a condição de cicatrização baseado numa tabela de escores que variava de 0 a 16. Quanto maior o escore melhor o grau de cicatrização. RESULTADOS: Na avaliação do estudo morfológico, que quantifica a evolução e o grau de cicatrização, como resultado final do processo cicatricial, o grupo aroeira foi superior ao grupo veículo (pPURPOSE: Verify, from a morphologic and tensional view point, the effect of the 10% aqueous extract of aroeira-do-sertão on the colonic anastomosis, during the occurrence of 10% acetic acid induced colitis, in Wistar rats. METHODS: There were used 48 Wistar rats, distributed in two groups. All animals were subjected to induction of colitis by aqueous solution of 10% acetic acid. Twenty-four hours later, the animals

  19. The long-term effect of acupuncture for patients with chronic tension-type headache: study protocol for a randomized controlled trial.

    Science.gov (United States)

    Lu, Lingyun; Zheng, Hui; Zheng, Qianhua; Hao, Xinyu; Zhou, Siyuan; Zhang, Shusen; Wei, Tao; Gao, Tao; Duan, Duoxi; Zhao, Ling; Li, Ning; Li, Ying

    2017-10-03

    The effectiveness of acupuncture for patients with chronic tension-type headache (CTTH) is controversial. In this article, we report the protocol for a randomized controlled trial aiming to evaluate the long-term effect of acupuncture for CTTH, in comparison with superficial acupuncture. A two-armed, parallel-design, patient-assessor blind, randomized controlled trial is underway in China. A total of 218 participants with CTTH will be randomly assigned to the treatment group or the control group in a 1:1 ratio. Participants in the treatment group and control group will receive acupuncture or superficial acupuncture treatments in a fixed prescription of acupoints respectively, for a total of 20 sessions over 8 weeks. The posttreatment follow-up period will be 24 weeks. The primary outcome will be the proportion of responders assessed at week 16 after randomization. The secondary outcomes will include the number of headache days, the mean intensity of headache, the reduction of medication intake, results from the 36-item short form health survey, the Hamilton Depression Scale and the Hamilton Anxiety Scale, the number of participants with adverse events, the expectation value of acupuncture treatment, and the intensity of deqi sensation. The first five secondary outcomes will be assessed or calculated at baseline, and at 4, 8, 12, 16, 20, 24, 28, and 32 weeks after randomization. Moreover, the expectation value will be collected at baseline and at week 8 after randomization, the intensity of deqi sensation will be assessed at 5 minutes after each treatment and adverse events will be summarized at the end of the follow-up period. Results from this trial will provide evidence for the long-term effect of acupuncture for CTTH with a long follow-up period. ClinicalTrial.gov NCT03133884 . Registered on 25 April 2017.

  20. The dynamics of nucleation and growth of a particle in the ternary alloy melt with anisotropic surface tension.

    Science.gov (United States)

    Chen, Ming-Wen; Li, Lin-Yan; Guo, Hui-Min

    2017-08-28

    The dynamics of nucleation and growth of a particle affected by anisotropic surface tension in the ternary alloy melt is studied. The uniformly valid asymptotic solution for temperature field, concentration field, and interface evolution of nucleation and particle growth is obtained by means of the multiple variable expansion method. The asymptotic solution reveals the critical radius of nucleation in the ternary alloy melt and an inward melting mechanism of the particle induced by the anisotropic effect of surface tension. The critical radius of nucleation is dependent on isotropic surface tension, temperature undercooling, and constitutional undercooling in the ternary alloy melt, and the solute diffusion melt decreases the critical radius of nucleation. Immediately after a nucleus forms in the initial stage of solidification, the anisotropic effect of surface tension makes some parts of its interface grow inward while some parts grow outward. Until the inward melting attains a certain distance (which is defined as "the melting depth"), these parts of interface start to grow outward with other parts. The interface of the particle evolves into an ear-like deformation, whose inner diameter may be less than two times the critical radius of nucleation within a short time in the initial stage of solidification. The solute diffusion in the ternary alloy melt decreases the effect of anisotropic surface tension on the interface deformation.

  1. Effects of hydrophilicity/lipophilicity of nano-TiO2 on surface tension of TiO2-water nanofluids

    Science.gov (United States)

    Zhang, Shenghan; Han, Xiaoxue; Tan, Yu; Liang, Kexin

    2018-01-01

    Platinum plate method based on Wilhelmy plate was used to measure the surface tension of hydrophilic nano-titanium dioxide-deionized water (nano-TiO2- DIW) fluids and hydrophilic lipophilic nano-TiO2-DIW fluids. Experimental results show that the surface adsorption of hydrophilic lipophilic nano-TiO2 is positive adsorption, and hydrophilic nano-TiO2 is negative adsorption. The hydrophilic nano-TiO2 in deionized water increases the surface tension of base fluid, and hydrophilic lipophilic nano-TiO2 in deionized water decreases. The surface tension of hydrophilic TiO2-DIW nanofluids increases, and hydrophilic lipophilic TiO2-DIW nanofluids decreases linearly with an increase in the natural logarithm of the molar concentration of nanofluids.

  2. Comparison of the intraocular pressure-lowering effect and safety of brimonidine/timolol fixed combination and 0.5% timolol in normal-tension glaucoma patients.

    Science.gov (United States)

    Kim, Joon Mo; Kim, Tae-Woo; Kim, Chan Yun; Kim, Hwang Ki; Park, Ki Ho

    2016-01-01

    To compare the therapeutic efficacy and safety of brimonidine/timolol fixed-combination (BTFC) and 0.5% timolol ophthalmic solution in normal-tension glaucoma (NTG) patients. This was a multi-institution, randomized, active-controlled, open-label, parallel-group study. After a full ophthalmic and glaucoma examination, a total of 110 NTG patients--55 undergoing therapy with BTFC and 55 0.5%, with timolol--participated in this study. Among them, 1 failed to meet the inclusion/exclusion criteria, 10 revoked their consent to participate in the study, 3 had adverse reactions, and 1 had a drug adherence rate of less than 70%. Ultimately, a total of 95 patients--48 in the BTFC group and 47 in the 0.5% timolol group--completed the study. The study visits took place at baseline and at 4 and 12 weeks. Diurnal IOP was measured at 9 a.m., 11 a.m., and 5 p.m. during the baseline visit and the visit at 12 weeks after eye-drop instillation. At each follow-up visit, compliance was assessed. Throughout the study, all adverse events were recorded and monitored by the investigators. The average difference in IOP change measured at 11 a.m. 12 weeks after administration between the two groups was 2.10 ± 2.59 mmHg. The BTFC group had a better IOP-lowering effect at all time points than did the 0.5% timolol group. The ratio of patients whose average IOP had decreased by >20% after 4 and 12 weeks was 50 and 56% in the BTFC group, respectively, whereas it was 29.41 and 23.53% in the 0.5% timolol group, respectively (p = 0.034, <0.001). BTFC has a superior IOP-lowering effect than 0.5% timolol in NTG patients.

  3. Competing effects of viscosity and surface-tension depression on the hygroscopicity and CCN activity of laboratory surrogates for oligomers in atmospheric aerosol

    Science.gov (United States)

    Hodas, N.; Zuend, A.; Shiraiwa, M.; Flagan, R. C.; Seinfeld, J.; Schilling, K.; Berkemeier, T.

    2015-12-01

    The presence of oligomers in biomass burning aerosol, as well as secondary organic aerosol derived from other sources, influences particle viscosity and can introduce kinetic limitations to water uptake. This, in turn, impacts aerosol optical properties and the efficiency with which these particles serve as cloud condensation nuclei (CCN). To explore the influence of organic-component viscosity on aerosol hygroscopicity, the water-uptake behavior of aerosol systems comprised of polyethylene glycol (PEG) and mixtures of PEG and ammonium sulfate (AS) was measured under sub- and supersaturated relative humidity (RH) conditions. Experiments were conducted with systems containing PEG with average molecular weights ranging from 200 to 10,000 g/mol, corresponding to a range in viscosity of 0.004 - 4.5 Pa s under dry conditions. While evidence suggests that viscous aerosol components can suppress water uptake at RH activity with increasing PEG molecular weight was observed. We attribute this to an increase in the efficiency with which PEG serves as a surfactant with increasing molecular weight. This effect is most pronounced for PEG-AS mixtures and, in fact, a modest increase in CCN activity is observed for the PEG 10,000-AS mixture as compared to pure AS, as evidenced by a 4% reduction in critical activation diameter. Experimental results are compared with calculations of hygroscopic growth at thermodynamic equilibrium using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model and the potential influence of kinetic limitations to observed water uptake is further explored with the Kinetic Multi-Layer Model of Gas-Particle Interactions. Results suggest the competing effects of organic-component viscosity and surface-tension depression may lead to RH-dependent differences in hygroscopicity for oligomers and other surface-active compounds present in atmospheric aerosols, for which PEG serves as a surrogate in these experiments.

  4. The effect of myofascial release and microwave diathermy combined with acupuncture versus acupuncture therapy in tension-type headache patients: A pragmatic randomized controlled trial.

    Science.gov (United States)

    Georgoudis, George; Felah, Bledjana; Nikolaidis, Pantelis; Damigos, Dimitrios

    2017-12-20

    Nonpharmacological therapies for tension-type headache (TTH) and cervicogenic cephalalgia are often a treatment choice, despite the weak to moderate evidence. The aim of this study was to compare the effectiveness of an acupuncture/stretching protocol versus acupuncture/stretching plus physiotherapy techniques, in patients with TTH cephalalgia. A single-blind, prospective, multicentre, randomized controlled trial was designed considering the pragmatic situation of administering such protocols and treating the 44 headache patients participating in this study. The patients were randomly assigned in 2 treatment groups (control group, n = 20, acupuncture/stretching; experimental group, n = 24, acupuncture/stretching plus physiotherapy) and completed 10 treatment sessions within 4 weeks with measurements taking place before treatment, after the fifth treatment and after the 10th treatment. The mechanical pressure pain threshold (PPT) was considered as the main outcome measure, using a mechanical algometer to measure 7 bilateral somatic points. Acupuncture in both groups included 17-20 acupuncture points, whereas stretching was initially taught and subsequently self-administered (self-stretches), following a standardized set of movements of the cervical spine. Physiotherapy consisted of microwave diathermy and myofascial release with hands-on techniques. An improvement was noted in both groups/treatments regarding the main outcome measure PPT, all the way from the first to fifth and the 10th treatment, at all measuring sites and at all measurements in both groups (p acupuncture and stretching but further PPT improvements were evidenced when physiotherapy hands-on techniques were added. In clinical terms, the combination of physiotherapy in the form of myofascial release and microwave diathermy with acupuncture and stretching in order to improve the analgesic effect (PPT) is strongly recommended. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Hofmeister salt effects on surface tension arise from partitioning of anions and cations between bulk water and the air-water interface.

    Science.gov (United States)

    Pegram, Laurel M; Record, M Thomas

    2007-05-17

    We apply a recently developed surface-bulk partitioning model to interpret the effects of individual Hofmeister cations and anions on the surface tension of water. The most surface-excluded salt (Na2SO4) provides a minimum estimate for the number of water molecules per unit area of the surface region of 0.2 H2O A-2. This corresponds to a lower bound thickness of the surface region of approximately 6 A, which we assume is a property of this region and not of the salt investigated. At salt concentrations anions and cations follow the conventional Hofmeister series, qualitative rankings of ions based on their effects on protein processes (folding, precipitation, assembly). Most anions that favor processes that expose protein surface to water (e.g., SCN-), and hence must interact favorably with (i.e., accumulate at) protein surface, are also accumulated at the air-water interface (Kp >1, e.g., Kp,SCN- =1.6). Most anions that favor processes that remove protein surface from water (e.g., F-), and hence are excluded from protein surface, are also excluded from the air-water interface (Kp,F- = 0.5). The guanidinium cation, a strong protein denaturant and therefore accumulated at the protein surface exposed in unfolding, is somewhat excluded from the air-water surface (Kp,GuH+ = 0.7), but is much less excluded than alkali metal cations (e.g., Kp,Na+ identical with 0, Kp,K+ = 0.1). Hence, cation Kp values for the air-water surface appear shifted (toward exclusion) as compared with values inferred for interactions of these cations with protein surface.

  6. ET-1 modulates KCa-channel activity and arterial tension in normoxic and hypoxic human pulmonary vasculature.

    Science.gov (United States)

    Peng, W; Michael, J R; Hoidal, J R; Karwande, S V; Farrukh, I S

    1998-10-01

    The molecular mechanisms by which endothelin (ET)-1 induces pulmonary hypertension are poorly understood. We investigated the effects of ET-1 on outward K+ currents of normoxic and chronically hypoxic human pulmonary arterial (PA) smooth muscle cells (HPSMCs). In normoxic HPSMCs, ET-1 has dual effects. In intact cells, 5 nM ET-1 activates the large-conductance and Ca2+-activated K+ (KCa)-channel current [IK(Ca)] by increasing intracellular Ca2+ concentration, whereas it directly inhibits IK(Ca) in isolated membrane patches. At a higher concentration (10 nM), ET-1-induced IK(Ca) inhibition predominates. In hypoxic HPSMCs, ET-1 at 5 nM significantly reduces IK(Ca). The ETA-receptor antagonist BQ-123 reverses the ET-1-induced decrease in IK(Ca). Chronic BQ-123 treatment also prevents the hypoxia-induced decrease in IK(Ca). In PA rings obtained from human organ donors, ET-1 causes a concentration-dependent increase in tension. The ET-1-mediated increase in tension is reversed by a KCa-channel agonist. The increase in tension at the highest concentration studied (9 nM) was more pronounced in PA rings obtained from patients with chronic obstructive pulmonary disease. These results imply that an ET-1-induced decrease in IK(Ca) contributes to chronic hypoxia-induced pulmonary hypertension.

  7. Laser-induced photodynamic effect

    Science.gov (United States)

    Kolarova, Hana; Kubinek, Roman; Navratil, Leos; Strnad, Miroslav; Reblova, Kamila; Skopek, Jiri

    2001-10-01

    Photodynamic therapy is a treatment that is used for destruction of certain tumors. The treatment is performed with photosensitizers that generate reactive oxygen species in the presence of light and oxygen. The absorption and fluorescence spectra of the ClAlPcS2 and ZnPcS2 photosensitizers were measured. From this analysis a semiconductor laser emitting a beam of 50 mW cw power at the wavelength of 675 nm for our experiments was chosen, because this wavelength corresponded with the absorption maximum (675 nm) in long-wave region of the visible part of electromagnetic spectra. B16 (cells line of mouse melanoma) was chosen as a standard testing system for definition of the in vitro phototoxicity after photodynamic reaction. The optimal phototoxic effect on B16 cells was observed at 2 (mu) g/ml ClAlPcS2 in combination with laser irradiation of 10 J/cm2.

  8. Tension stimulation drives tissue formation in scaffold-free systems

    Science.gov (United States)

    Lee, Jennifer K.; Huwe, Le W.; Paschos, Nikolaos; Aryaei, Ashkan; Gegg, Courtney A.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2017-08-01

    Scaffold-free systems have emerged as viable approaches for engineering load-bearing tissues. However, the tensile properties of engineered tissues have remained far below the values for native tissue. Here, by using self-assembled articular cartilage as a model to examine the effects of intermittent and continuous tension stimulation on tissue formation, we show that the application of tension alone, or in combination with matrix remodelling and synthesis agents, leads to neocartilage with tensile properties approaching those of native tissue. Implantation of tension-stimulated tissues results in neotissues that are morphologically reminiscent of native cartilage. We also show that tension stimulation can be translated to a human cell source to generate anisotropic human neocartilage with enhanced tensile properties. Tension stimulation, which results in nearly sixfold improvements in tensile properties over unstimulated controls, may allow the engineering of mechanically robust biological replacements of native tissue.

  9. Measuring Surface Tension of a Flowing Soap Film

    Science.gov (United States)

    Sane, Aakash; Kim, Ildoo; Mandre, Shreyas

    2016-11-01

    It is well known that surface tension is sensitive to the presence of surfactants and many conventional methods exist to measure it. These techniques measure surface tension either by intruding into the system or by changing its geometry. Use of conventional methods in the case of a flowing soap film is not feasible because intruding the soap film changes surface tension due to Marangoni effect. We present a technique in which we measure the surface tension in situ of a flowing soap film without intruding into the film. A flowing soap film is created by letting soap solution drip between two wires. The interaction of the soap film with the wires causes the wires to deflect which can be measured. Surface tension is calculated using a relation between curvature of the wires and the surface tension. Our measurements indicate that the surface tension of the flowing soap film for our setup is around 0.05 N/m. The nature of this technique makes it favorable for measuring surface tension of flowing soap films whose properties change on intrusion.

  10. Space station induced electromagnetic effects

    Science.gov (United States)

    Singh, N.

    1988-01-01

    Several mechanisms which can cause electric (E) and magnetic (B) field contaminations of the Space Station environment are identified. The level of E and B fields generated by some of them such as the motion of the vehicle across the ambient magnetic field B(0) and the 20-kHz leakage currents and charges can be controlled by proper design considerations. On the other hand, there are some mechanisms which are inherent to the interaction of large vehicles with the plasma and probably their contributions to E and B fields cannot be controlled; these include plasma waves in the wake and ram directions and the effects of the volume current generated by the ionization of neutrals. The interaction of high-voltage solar arrays with plasma is yet another rich source of E and B fields and it is probably uncontrollable. Wherever possible, quantitative estimates of E and B are given. A set of recommendations is included for further study in areas where indepth knowledge is seriously lacking.

  11. Innovative Concrete Repairing Technique Using Post Tensioning Steel Straps

    Directory of Open Access Journals (Sweden)

    Ma Chau-Khun

    2017-01-01

    Full Text Available In this paper, innovative technique using low-cost recycled steel straps confinement to repair load-induced damaged high-strength concrete (HSC columns were studied. This paper explains the effects of repairing technique using post tensioning steel straps. A series of experimental test was carried out to investigate the stress-strain relationships of such concrete. A total of 6 HSC columns were compressed 50% of their ultimate strength, then repaired by using steel straps. The proposed repairing technique significantly improved the performance of damaged concrete columns, in both strength and ductility. It was evidenced from this study that the steel strapping confining technique is effective in repairing of damaged HSC columns but ensured reasonable operating costs.

  12. Determination of residual stresses and natural frequencies of roll-tensioned disc by a dynamic simulation of the rolling process

    Science.gov (United States)

    Skordaris, G.; Bouzakis, K.-D.; Tasoulas, D.

    2017-02-01

    Roll tensioning is a common method for increasing locally the superficial strength of thin circular saws and in this way their dynamic stability. Through roll tensioning, residual stresses are induced into the disc material leading to a significant enhancement of its dynamic stiffness. In this paper, a FEM-methodology is proposed for determining the developed residual stresses in the discs after rolling and for investigating their effects on the circular saw natural frequencies. More specifically, a 3D-FEM model was developed for the dynamic simulation of the rolling process on circular saws, using the LS-DYNA software. This model enables the explicit determination of the developed residual stresses in the roll-tensioned discs. Furthermore, the natural frequencies of the pre-stressed circular saws were calculated by the ANSYS software. In these calculations, the already determined residual stresses were taken into consideration. Different distances of the roll-tensioned zone from the disc centre were taken into account for estimating their effect on the disc’s natural frequencies. By the proposed methodology, optimum roll-tensioning conditions can be predicted for improving the dynamic behaviour of thin circular saws during cutting.

  13. Near-infrared spectroscopy as a possible device for continuous monitoring of arterial carbon dioxide tension during cardiac surgery.

    Science.gov (United States)

    Park, C S; Kwak, J G; Lee, C; Lee, C-H; Lee, S K; Kim, Y L

    2011-11-01

    Insufflation of carbon dioxide (CO(2)) to the operative field has been used to prevent major organ injury attributed to air embolisms in cardiac surgery. However, it may be preferable to avoid hypercapnia induced by CO(2) insufflation, owing to its potentially harmful effect. To investigate the effectiveness of near-infrared spectroscopy (NIRS) as a possible method for continuous monitoring of arterial CO(2) tension during cardiac surgery, we evaluated the correlation between the change in arterial CO(2) tension and the change in regional cerebral oxygen saturation (rScO(2)) obtained from NIRS in as controlled a condition as possible. Thirty patients who underwent surgical correction for atrial or ventricular septal defects were enrolled in this study. Patients who had pulmonary hypertension or other intracardiac anomalies were excluded. Anesthetic and cardiopulmonary bypass (CPB) management were conducted according to our standard institutional practice. Data obtained from arterial blood gas analyses and corresponding regional cerebral oxygen saturation (rScO(2)) recorded from NIRS before and after the insufflations of CO(2) during CPB were used for analysis. The change in arterial CO(2) tension correlated with the change in rScO(2) in the left hemisphere (r = 0.681, p arterial CO(2) tension during mild hypothermic CPB, NIRS might be a possible non-invasive method for monitoring of arterial CO(2) tension without incurring additional cost in this setting.

  14. Effectiveness of Retropubic Tension-Free Vaginal Tape and Transobturator Inside-Out Tape Procedures in Women With Overactive Bladder and Stress Urinary Incontinence

    Science.gov (United States)

    Han, Ji-Yeon; Choo, Myung-Soo; Lee, Young-Suk; Seo, Ju Tae; Kim, Jang Hwan; Kim, Young Ho

    2013-01-01

    Purpose We compared the effectiveness of the retropubic tension-free vaginal tape (TVT) and the transobturator inside-out tape (TVT-O) in treating symptoms of overactive bladder (OAB) in women with stress urinary incontinence (SUI). Methods Women with urodynamic SUI and OAB (mean urgency episodes ≥1 and frequency ≥8/24 hours on a 3-day voiding diary) were assigned to the TVT or TVT-O group. Preoperative measures were based on a urodynamic study, 3-day voiding diary, the Bristol Female Lower Urinary Tract Symptoms questionnaire (BFLUTSSF), and the urgency perception scale (UPS). At 12 postoperative months, the 3-day voiding diary, symptoms questionnaire, patient satisfaction, and standing stress test were assessed. The primary endpoint was change in the number of urgency episodes/24 hours from baseline to 12 months. Results In this group of 132 women, 42 received TVT and 90 received TVT-O. The mean urgency episodes/24 hours decreased from 6.3±5.5 to 1.6±3.2 in the TVT group and from 5.1±4.4 to 1.8±3.0 in the TVT-O group. The mean percent change was significantly greater after TVT than after TVT-O (73% vs. 60%, P=0.049). All subscales of BFLUTSSF and UPS were significantly improved using either method, with significantly greater improvement seen in the quality of life (QoL) domain after TVT (P=0.002). There were no significant differences in the cure and satisfaction rates between the two groups. Conclusions Intervention with the TVT or the TVT-O significantly improved symptoms of OAB in women with SUI and OAB. Urgency and QoL significantly improved after TVT compared with that after TVT-O. PMID:24143294

  15. Ion beam induced luminescence: Relevance to radiation induced bystander effects

    Science.gov (United States)

    Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.

    2012-10-01

    The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

  16. Chemical responses to modified lignin composition in tension wood of hybrid poplar (Populus tremula x Populus alba).

    Science.gov (United States)

    Al-Haddad, Jameel M; Kang, Kyu-Young; Mansfield, Shawn D; Telewski, Frank W

    2013-04-01

    The effect of altering the expression level of the F5H gene was investigated in three wood tissues (normal, opposite and tension wood) in 1-year-old hybrid poplar clone 717 (Populus tremula × Populus alba L.), containing the F5H gene under the control of the C4H promoter. Elevated expression of the F5H gene in poplar has been previously reported to increase the percent syringyl content of lignin. The wild-type and three transgenic lines were inclined 45° for 3 months to induce tension wood formation. Tension and opposite wood from inclined trees, along with normal wood from control trees, were analyzed separately for carbohydrates, lignin, cellulose crystallinity and microfibril angle (MFA). In the wild-type poplar, the lignin in tension wood contained a significantly higher percentage of syringyl than normal wood or opposite wood. However, there was no significant difference in the percent syringyl content of the three wood types within each of the transgenic lines. Increasing the F5H gene expression caused an increase in the percent syringyl content and a slight decrease in the total lignin in normal wood. In tension wood, the addition of a gelatinous layer in the fiber walls resulted in a consistently lower percentage of total lignin in the tissue. Acid-soluble lignin was observed to increase by up to 2.3-fold in the transgenic lines. Compared with normal wood and opposite wood, cell wall crystallinity in tension wood was higher and the MFA was smaller, as expected, with no evidence of an effect from modifying the syringyl monomer ratio. Tension wood in all the lines contained consistently higher total sugar and glucose percentages when compared with normal wood within the respective lines. However, both sugar and glucose percentages were lower in the tension wood of transgenic lines when compared with the tension wood of wild-type trees. Evaluating the response of trees with altered syringyl content to gravity will improve our understanding of the changes

  17. A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients

    NARCIS (Netherlands)

    Wahr, J. A.; Trouwborst, A.; Spence, R. K.; Henny, C. P.; Cernaianu, A. C.; Graziano, G. P.; Tremper, K. K.; Flaim, K. E.; Keipert, P. E.; Faithfull, N. S.; Clymer, J. J.

    1996-01-01

    A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension. Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute

  18. Effect of second-order and fully nonlinear wave kinematics on a tension-leg-platform wind turbine in extreme wave conditions

    DEFF Research Database (Denmark)

    Pegalajar Jurado, Antonio Manuel; Borg, Michael; Robertson, Amy

    2017-01-01

    In this study, we assess the impact of different wave kinematics models on the dynamic response of a tension-leg-platform wind turbine. Aero-hydro-elastic simulations of the floating wind turbine are carried out employing linear, second-order, and fully nonlinear kinematics using the Morison equa...

  19. Low physiologic oxygen tensions reduce proliferation and differentiation of human multipotent mesenchymal stromal cells

    Directory of Open Access Journals (Sweden)

    Handgretinger Rupert

    2010-01-01

    Full Text Available Abstract Background Human multipotent mesenchymal stromal cells (MSC can be isolated from various tissues including bone marrow. Here, MSC participate as bone lining cells in the formation of the hematopoietic stem cell niche. In this compartment, the oxygen tension is low and oxygen partial pressure is estimated to range from 1% to 7%. We analyzed the effect of low oxygen tensions on human MSC cultured with platelet-lysate supplemented media and assessed proliferation, morphology, chromosomal stability, immunophenotype and plasticity. Results After transferring MSC from atmospheric oxygen levels of 21% to 1%, HIF-1α expression was induced, indicating efficient oxygen reduction. Simultaneously, MSC exhibited a significantly different morphology with shorter extensions and broader cell bodies. MSC did not proliferate as rapidly as under 21% oxygen and accumulated in G1 phase. The immunophenotype, however, was unaffected. Hypoxic stress as well as free oxygen radicals may affect chromosomal stability. However, no chromosomal abnormalities in human MSC under either culture condition were detected using high-resolution matrix-based comparative genomic hybridization. Reduced oxygen tension severely impaired adipogenic and osteogenic differentiation of human MSC. Elevation of oxygen from 1% to 3% restored osteogenic differentiation. Conclusion Physiologic oxygen tension during in vitro culture of human MSC slows down cell cycle progression and differentiation. Under physiological conditions this may keep a proportion of MSC in a resting state. Further studies are needed to analyze these aspects of MSC in tissue regeneration.

  20. Managing tension headaches at home

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000421.htm Managing tension headaches at home To use the sharing ... have glasses, use them. Learn and practice stress management. Some people find relaxation exercises or meditation helpful. ...

  1. Tension pile study : final report.

    Science.gov (United States)

    1970-07-01

    This report contains the results of a short term study of a pile in tension loads. The piles tested were driven on Louisiana Department of Highway's property in response to preceding research work entitled "Stability of Slender Prestressed Concrete P...

  2. Pathomorphological effects of Alloxan induced acute hypoglycaemia ...

    African Journals Online (AJOL)

    In the present investigation the pathological effects of alloxan induced acute hypoglycaemia were studied in rabbits. New Zealand White rabbits, 1–1.5 kg body weight, were administered alloxan @100 mg/kg b.w., as a single intravenous dose. Blood glucose levels were monitored (0 h, 20 min, 1 h, and then hourly up to 5 h) ...

  3. Experimentally induced secondary cryptorchidism: Effects on growth ...

    African Journals Online (AJOL)

    Cryptorchidism may interfere with spermatogenesis but not the functions of the Leydig cells. This study investigated the effects of induced Secondary cryptorchidism growth performance of Djallonké lambs. A total of eighteen Djallonké lambs were assigned randomly to one of six treatments in a 2 × 3 factorial arrangement of ...

  4. Neutron induced bystander effect among zebrafish embryos

    Science.gov (United States)

    Ng, C. Y. P.; Kong, E. Y.; Kobayashi, A.; Suya, N.; Uchihori, Y.; Cheng, S. H.; Konishi, T.; Yu, K. N.

    2015-12-01

    The present paper reported the first-ever observation of neutron induced bystander effect (NIBE) using zebrafish (Danio rerio) embryos as the in vivo model. The neutron exposure in the present work was provided by the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. Two different strategies were employed to induce NIBE, namely, through directly partnering and through medium transfer. Both results agreed with a neutron-dose window (20-50 mGy) which could induce NIBE. The lower dose limit corresponded to the threshold amount of neutron-induced damages to trigger significant bystander signals, while the upper limit corresponded to the onset of gamma-ray hormesis which could mitigate the neutron-induced damages and thereby suppress the bystander signals. Failures to observe NIBE in previous studies were due to using neutron doses outside the dose-window. Strategies to enhance the chance of observing NIBE included (1) use of a mono-energetic high-energy (e.g., between 100 keV and 2 MeV) neutron source, and (2) use of a neutron source with a small gamma-ray contamination. It appeared that the NASBEE facility used in the present study fulfilled both conditions, and was thus ideal for triggering NIBE.

  5. Sexual side effects induced by psychotropic drugs

    DEFF Research Database (Denmark)

    Kristensen, Ellids

    2002-01-01

    The majority of psychotropic drugs entail sexual side effects. The sexual side effects may reduce quality of life and may give rise to non-compliance. For example, 30-60 per cent of patients treated with antidepressants are known to develop a sexual dysfunction. However, some psychotropic drugs...... with no or very few sexual side effects have begun to emerge. The treatment of sexual side effects induced by psychotropic drugs may consist of: modified sexual habits, reduction in dosage, switching to another medication, possibly in combination with different psychotropic agents, other varieties...

  6. Corrosion characteristics of unprotected post-tensioning strands under stress.

    Science.gov (United States)

    2014-05-01

    An investigation was conducted to determine the effect of stress condition : and environmental exposure on corrosion of post-tensioned strands during ungrouted periods. : Exposures for periods of up to 4 weeks of stressed, as-received strand placed i...

  7. Surface tension confined liquid cryogen cooler

    Science.gov (United States)

    Castles, Stephen H.; Schein, Michael E.

    1989-04-01

    A cryogenic cooler is provided for use in craft such as launch, orbital, and space vehicles subject to substantial vibration, changes in orientation, and weightlessness. The cooler contains a small pore, large free volume, low density material to restrain a cryogen through surface tension effects during launch and zero-g operations and maintains instrumentation within the temperature range of 10 to 140 K. The cooler operation is completely passive, with no inherent vibration or power requirements.

  8. The effects of wire diameter and an additional lateral wire on pin and tension-band fixation subjected to cyclic loads.

    Science.gov (United States)

    Neat, B; Kowaleski, M P; Litsky, A S; Boudrieau, R J

    2006-01-01

    Despite reports of frequent complications, pin and tension- band wire remains the most common repair of simple olecranon fractures and osteotomies. A recent mechanical study found wire diameter to be the key determinant of pin and tension-band construct strength; models with 1.25-mm wire were much stronger than those with standard 1.0-mm wire exposed to single loads to failure. Additionally, fixation strength was also increased when a lateral wire was used in combination with a standard figure-of-eight wire. The purpose of the present study was to assess any advantages provided by 1.25-mm wire or an additional lateral wire over 1.0-mm wire for pin and tension-band fixation subjected to cyclic loading. Pin and tension-band fixation was applied to plastic olecranon osteotomy models with three wire configurations: 1.0-mm figure-of-eight, 1.25-mm figure-of-eight, and combined 1.0-mm figure-of-eight and lateral. Cyclic load was applied while caudal osteotomy displacement was measured with an extensometer. The three groups were compared in terms of cycles to failure, mean minimum displacement, mean maximum displacement, and mean displacement per cycle. Models with an additional lateral wire survived significantly more cycles than those with a solitary 1.0-mm figure-of-eight wire, although caudal osteotomy displacements were not significantly different. Conversely, models with 1.25-mm wire allowed significantly smaller minimum and maximum displacements than those with 1.0-mm wire, but did not survive significantly more cycles. It therefore appears that clinical use of 1.25-mm wire may improve stability, while use of an additional lateral wire may improve durability.

  9. A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients.

    Science.gov (United States)

    Wahr, J A; Trouwborst, A; Spence, R K; Henny, C P; Cernaianu, A C; Graziano, G P; Tremper, K K; Flaim, K E; Keipert, P E; Faithfull, N S; Clymer, J J

    1996-01-01

    A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension. Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute normovolemic hemodilution (ANH). Hemodynamic and oxygen transport data were collected before and after ANH, immediately after PFC infusion, and at approximate 15-min intervals throughout the surgical period. There were no clinically significant hemodynamic changes associated with the administration of the PFC emulsion. There was a significant increase in mixed venous oxygen tension (PVO2) after the PFC infusion, while cardiac output and oxygen consumption were unchanged. As surgery progressed, the hemoglobin concentration decreased with ongoing blood loss while PVO2 values remained at or above predosing levels. Peak perflubron blood levels were 0.8 g/dL immediately postinfusion, and approximately 0.3 g/dL at 1 h. This pilot study demonstrates that administration of perflubron emulsion results in measurable changes in mixed venous oxygen tension during intraoperative ANH.

  10. Water surface tension modulates the swarming mechanics of Bacillus subtilis.

    Science.gov (United States)

    Ke, Wan-Ju; Hsueh, Yi-Huang; Cheng, Yu-Chieh; Wu, Chih-Ching; Liu, Shih-Tung

    2015-01-01

    Many Bacillus subtilis strains swarm, often forming colonies with tendrils on agar medium. It is known that B. subtilis swarming requires flagella and a biosurfactant, surfactin. In this study, we find that water surface tension plays a role in swarming dynamics. B. subtilis colonies were found to contain water, and when a low amount of surfactin is produced, the water surface tension of the colony restricts expansion, causing bacterial density to rise. The increased density induces a quorum sensing response that leads to heightened production of surfactin, which then weakens water surface tension to allow colony expansion. When the barrier formed by water surface tension is breached at a specific location, a stream of bacteria swarms out of the colony to form a tendril. If a B. subtilis strain produces surfactin at levels that can substantially weaken the overall water surface tension of the colony, water floods the agar surface in a thin layer, within which bacteria swarm and migrate rapidly. This study sheds light on the role of water surface tension in regulating B. subtilis swarming, and provides insight into the mechanisms underlying swarming initiation and tendril formation.

  11. Pulmonary surfactant surface tension influences alveolar capillary shape and oxygenation.

    Science.gov (United States)

    Ikegami, Machiko; Weaver, Timothy E; Grant, Shawn N; Whitsett, Jeffrey A

    2009-10-01

    Alveolar capillaries are located in close proximity to the alveolar epithelium and beneath the surfactant film. We hypothesized that the shape of alveolar capillaries and accompanying oxygenation are influenced by surfactant surface tension in the alveolus. To prove our hypothesis, surfactant surface tension was regulated by conditional expression of surfactant protein (SP)-B in Sftpb(-/-) mice, thereby inhibiting surface tension-lowering properties of surfactant in vivo within 24 hours after depletion of Sftpb. Minimum surface tension of isolated surfactant was increased and oxygen saturation was significantly reduced after 2 days of SP-B deficiency in association with deformation of alveolar capillaries. Intravascularly injected 3.2-mum-diameter microbeads through jugular vein were retained within narrowed pulmonary capillaries after reduction of SP-B. Ultrastructure studies demonstrated that the capillary protrusion typical of the normal alveolar-capillary unit was reduced in size, consistent with altered pulmonary blood flow. Pulmonary hypertension and intrapulmonary shunting are commonly associated with surfactant deficiency and dysfunction in neonates and adults with respiratory distress syndromes. Increased surfactant surface tension caused by reduction in SP-B induced narrowing of alveolar capillaries and oxygen desaturation, demonstrating an important role of surface tension-lowering properties of surfactant in the regulation of pulmonary vascular perfusion.

  12. Propulsion Induced Effects (PIE) Test Program

    Science.gov (United States)

    Cappuccio, Gelsomina; Won, Mark J.

    1999-01-01

    The Propulsion Induced Effects (PIE) test program is being lead by NASA Ames for Configuration Aerodynamics (CA). Representatives from CA, Technology Integration (TI), Inlet, and the Nozzle ITD's are working with Ames in defining and executing this test program. The objective of the CA 4-14 milestone is to assess the propulsion/airframe integration characteristics of the Technology Concept Airplane (TCA) and design variations using computational and experimental methods. The experimental aspect includes static calibrations, transonic and supersonic wind tunnel testing. The test program will generate a comprehensive database that will include all appropriate wind tunnel corrections, with emphasis placed on establishing the propulsion induced effects on the flight performance of the TCA.

  13. Surface tension of Nanofluid-type fuels containing suspended nanomaterials.

    Science.gov (United States)

    Tanvir, Saad; Qiao, Li

    2012-04-18

    The surface tension of ethanol and n-decane based nanofluid fuels containing suspended aluminum (Al), aluminum oxide (Al2O3), and boron (B) nanoparticles as well as dispersible multi-wall carbon nanotubes (MWCNTs) were measured using the pendant drop method by solving the Young-Laplace equation. The effects of nanoparticle concentration, size and the presence of a dispersing agent (surfactant) on surface tension were determined. The results show that surface tension increases both with particle concentration (above a critical concentration) and particle size for all cases. This is because the Van der Waals force between particles at the liquid/gas interface increases surface free energy and thus increases surface tension. At low particle concentrations, however, addition of particles has little influence on surface tension because of the large distance between particles. An exception is when a surfactant was used or when (MWCNTs) was involved. For such cases, the surface tension decreases compared to the pure base fluid. The hypothesis is the polymer groups attached to (MWCNTs) and the surfactant layer between a particle and the surround fluid increases the electrostatic force between particles and thus reduce surface energy and surface tension.

  14. Surface tension of Nanofluid-type fuels containing suspended nanomaterials

    Science.gov (United States)

    2012-01-01

    The surface tension of ethanol and n-decane based nanofluid fuels containing suspended aluminum (Al), aluminum oxide (Al2O3), and boron (B) nanoparticles as well as dispersible multi-wall carbon nanotubes (MWCNTs) were measured using the pendant drop method by solving the Young-Laplace equation. The effects of nanoparticle concentration, size and the presence of a dispersing agent (surfactant) on surface tension were determined. The results show that surface tension increases both with particle concentration (above a critical concentration) and particle size for all cases. This is because the Van der Waals force between particles at the liquid/gas interface increases surface free energy and thus increases surface tension. At low particle concentrations, however, addition of particles has little influence on surface tension because of the large distance between particles. An exception is when a surfactant was used or when (MWCNTs) was involved. For such cases, the surface tension decreases compared to the pure base fluid. The hypothesis is the polymer groups attached to (MWCNTs) and the surfactant layer between a particle and the surround fluid increases the electrostatic force between particles and thus reduce surface energy and surface tension. PMID:22513039

  15. Induced effects of advanced oxidation processes

    Science.gov (United States)

    Liu, Peng; Li, Chaolin; Zhao, Zhuanjun; Lu, Gang; Cui, Haibo; Zhang, Wenfang

    2014-02-01

    Hazardous organic wastes from industrial, military, and commercial activities represent one of the greatest challenges to human beings. Advanced oxidation processes (AOPs) are alternatives to the degradation of those organic wastes. However, the knowledge about the exact mechanisms of AOPs is still incomplete. Here we report a phenomenon in the AOPs: induced effects, which is a common property of combustion reaction. Through analysis EDTA oxidation processes by Fenton and UV-Fenton system, the results indicate that, just like combustion, AOPs are typical induction reactions. One most compelling example is that pre-feeding easily oxidizable organic matter can promote the oxidation of refractory organic compound when it was treated by AOPs. Connecting AOPs to combustion, it is possible to achieve some helpful enlightenment from combustion to analyze, predict and understand AOPs. In addition, we assume that maybe other oxidation reactions also have induced effects, such as corrosion, aging and passivation. Muchmore research is necessary to reveal the possibilities of induced effects in those fields.

  16. Induced effects of advanced oxidation processes.

    Science.gov (United States)

    Liu, Peng; Li, Chaolin; Zhao, Zhuanjun; Lu, Gang; Cui, Haibo; Zhang, Wenfang

    2014-02-07

    Hazardous organic wastes from industrial, military, and commercial activities represent one of the greatest challenges to human beings. Advanced oxidation processes (AOPs) are alternatives to the degradation of those organic wastes. However, the knowledge about the exact mechanisms of AOPs is still incomplete. Here we report a phenomenon in the AOPs: induced effects, which is a common property of combustion reaction. Through analysis EDTA oxidation processes by Fenton and UV-Fenton system, the results indicate that, just like combustion, AOPs are typical induction reactions. One most compelling example is that pre-feeding easily oxidizable organic matter can promote the oxidation of refractory organic compound when it was treated by AOPs. Connecting AOPs to combustion, it is possible to achieve some helpful enlightenment from combustion to analyze, predict and understand AOPs. In addition, we assume that maybe other oxidation reactions also have induced effects, such as corrosion, aging and passivation. Muchmore research is necessary to reveal the possibilities of induced effects in those fields.

  17. Effect of Added Surfactants on the Dynamic Interfacial Tension Behaviour of Alkaline/Diluted Heavy Crude Oil System Effet de l’ajout de tensioactifs sur le comportement dynamique de la tension interfaciale du système solution alcaline/brut dilué

    Directory of Open Access Journals (Sweden)

    Trabelsi S.

    2013-02-01

    Full Text Available This study has been undertaken to get a better understanding of the interactions between Enhanced Oil Recovery (EOR surfactants used in chemical flooding and in situ surfactants present in an heavy oil. We report an experimental study of dynamic Interfacial Tension (IFT behaviour of diluted heavy oil/surfactant enhanced-alkaline systems. The dynamic IFT was measured using pendant drop and spinning drop tensiometers. The dynamic IFT between diluted heavy oil and alkaline solution (pH 11 with no added surfactant increased sharply with time, which was attributed to the transfer of the in situ surfactant (produced by saponification of the acids groups present in the crude oil across the oil/water interface. The addition of Sodium Dodecyl Benzene Sulfonate (SDBS above the Critical Micellar Concentration (CMC ~ 0.002%, changed completely the dynamic IFT behaviour of the diluted heavy oil as the IFT strongly decreased and finally reached a plateau, of about 1.5 × 10-3 mN/m at a concentration of only 0.02%. We attributed the efficiency of SDBS to a synergistic effect between the in situ surfactant and the added surfactant that form a mixed interfacial monolayer, which is very efficient in decreasing the IFT to ultra low values and in resisting mass transfer across the oil/water interface. Cette étude a été réalisée pour mieux comprendre les interactions entre les tensioactifs utilisés pour la récupération assistée de pétrole et les tensioactifs in situ présents dans le brut. Nous expérimentons le comportement dynamique des tensions interfaciales (mesurées par les méthodes de goutte pendante et goutte tournante entre le brut lourd dilué et les solutions alcalines avec ajout de tensioactif. La tension interfaciale dynamique entre le brut dilué et une solution alcaline (pH 11 sans ajout de tensioactif croît fortement au cours du temps, cette augmentation est attribuée au transfert des tensioactifs in situ (produits par saponification des

  18. Matrix stiffness and oxigen tension modulate epigenetic conversion of mouse dermal fibroblasts into insulin producing cells.

    Directory of Open Access Journals (Sweden)

    Alessandro Zenobi

    2017-05-01

    Full Text Available In vivo, cells are surrounded by a three-dimensional (3-D organization of supporting matrix, neighboring cells and a gradient of chemical and mechanical signals (Antoni, et al., 2015. However, the present understanding of many biological processes is mainly based on two-dimensional (2-D systems that typically provides a static environment. In the present study, we tested two different 3-D culture systems and apply them to the epigenetic conversion of mouse dermal fibroblasts into insulin producing-cells (Pennarossa, et al., 2013; Brevini, et al., 2015, combining also the use of two oxygen tensions. In particular, cells were differentiated using the Polytetrafluoroethylene micro-bioreactor (PTFE and the Polyacrylamide (PAA gels with different stiffness (1 kPa; 4 kPa, maintained either in the standard 20% or in the more physiological 5% oxygen tensions. Standard differentiation performed on plastic substrates was assessed as a control. Cell morphology (Fig.1A, insulin expression and release were analyzed to evaluate the role of both stiffness and oxygen tension in the process. The results obtained showed that 1 kPa PAA gel and PTFE system induced a significantly higher insulin expression and release than plastic and 4 kPa PAA gel, especially in low oxygen condition (Fig.1B. Furthermore, comparing the efficiency of the two systems tested, 1 kPa PAA gel ensured a higher insulin transcription than PTFE (Fig.1C. Recent studies show the direct influence of substrates on lineage commitment and cell differentiation (Engler, et al., 2006; Evans, et al., 2009. The evidence here presented confirm that the use of an appropriate stiffness (similar to the pancreatic tissue, combined with a physiological oxygen tension, promote β-cell differentiation, with beneficial effects on cell functional activity and insulin release. The present results highlight the importance of 3-D cell rearrangement and oxigen tension to promote in vitro epigenetic conversion of

  19. Historical Tensions in Engineering Education

    DEFF Research Database (Denmark)

    Jamison, Andrew; Heymann, Matthias

    2012-01-01

    Ever since institutions for educating engineers first began to be ­established in Europe, there have been a number of fundamental tensions as to how that ­educating should best be conducted, what it should consist of, and who should do the educating. These tensions are based on different styles...... or approaches to ­engineering education that have developed historically in different parts of Europe and which have led to what we characterize as “theory-driven,” “practice-driven,” and “technology-driven” approaches. This chapter explores some of the historical roots of these tensions in medieval Europe...... and briefly traces their developmental trajectories through the subsequent formation of institutions of engineering ­education. It has been written as part of PROCEED (Program of Research on Opportunities and Challenges in Engineering Education in Denmark)....

  20. Induced charge effects on electrokinetic entry flow

    Science.gov (United States)

    Prabhakaran, Rama Aravind; Zhou, Yilong; Zhao, Cunlu; Hu, Guoqing; Song, Yongxin; Wang, Junsheng; Yang, Chun; Xuan, Xiangchun

    2017-06-01

    Electrokinetic flow, due to a nearly plug-like velocity profile, is the preferred mode for transport of fluids (by electroosmosis) and species (by electrophoresis if charged) in microfluidic devices. Thus far there have been numerous studies on electrokinetic flow within a variety of microchannel structures. However, the fluid and species behaviors at the interface of the inlet reservoir (i.e., the well that supplies the fluid and species) and microchannel are still largely unexplored. This work presents a fundamental investigation of the induced charge effects on electrokinetic entry flow due to the polarization of dielectric corners at the inlet reservoir-microchannel junction. We use small tracing particles suspended in a low ionic concentration fluid to visualize the electrokinetic flow pattern in the absence of Joule heating effects. Particles are found to get trapped and concentrated inside a pair of counter-rotating fluid circulations near the corners of the channel entrance. We also develop a depth-averaged numerical model to understand the induced charge on the corner surfaces and simulate the resultant induced charge electroosmosis (ICEO) in the horizontal plane of the microchannel. The particle streaklines predicted from this model are compared with the experimental images of tracing particles, which shows a significantly better agreement than those from a regular two-dimensional model. This study indicates the strong influences of the top/bottom walls on ICEO in shallow microchannels, which have been neglected in previous two-dimensional models.

  1. Effect of hypocarbia and hypercarbia on the antagonism of pancuronium-induced neuromuscular blockade with neostigmine in man.

    Science.gov (United States)

    Wirtavuori, K; Salmenperä, M; Tammisto, T

    1982-01-01

    The effects of variations in carbon dioxide concentration on the antagonism of pancuronium-induced neuromuscular block by neostigmine were studied in 21 patients: normocarbia (PE'CO2 5.4%, PaCO2 4.93 kPa, n = 7), hypocarbia (PE'CO2 3.6%, PaCO2 3.30 kPa, n = 7) and hypercarbia (PE'CO2 7.5%, PaCO2 7.13 kPa, n = 7). Mechanical and electromyographic responses to ulnar nerve stimulation (0.1 Hz and 2 Hz) were recorded. A 90% block during nitrous oxide in oxygen anaesthesia was maintained by incremental single injections of pancuronium and reversed with neostigmine 0.35 mg kg-1 with atropine 0.0175 mg kg-1. The recovery of twitch tension up to 50% was similar in all groups but thereafter slower in the hypercarbia group. The recovery times from 25% to 75% twitch tension correlated with PaCO2 (r = 0.55, P less than 0.05). A residual block of about 10% was seen in hypercarbic patients. However, the recovery of e.m.g. amplitude and train-of-four ratios was similar in all groups. Thus, the impaired recovery of twitch tension seems to be the result of depressed contractility rather than failure of neuromuscular transmission.

  2. Shape accuracy optimization for cable-rib tension deployable antenna structure with tensioned cables

    Science.gov (United States)

    Liu, Ruiwei; Guo, Hongwei; Liu, Rongqiang; Wang, Hongxiang; Tang, Dewei; Song, Xiaoke

    2017-11-01

    Shape accuracy is of substantial importance in deployable structures as the demand for large-scale deployable structures in various fields, especially in aerospace engineering, increases. The main purpose of this paper is to present a shape accuracy optimization method to find the optimal pretensions for the desired shape of cable-rib tension deployable antenna structure with tensioned cables. First, an analysis model of the deployable structure is established by using finite element method. In this model, geometrical nonlinearity is considered for the cable element and beam element. Flexible deformations of the deployable structure under the action of cable network and tensioned cables are subsequently analyzed separately. Moreover, the influence of pretension of tensioned cables on natural frequencies is studied. Based on the results, a genetic algorithm is used to find a set of reasonable pretension and thus minimize structural deformation under the first natural frequency constraint. Finally, numerical simulations are presented to analyze the deployable structure under two kinds of constraints. Results show that the shape accuracy and natural frequencies of deployable structure can be effectively improved by pretension optimization.

  3. Effects of ionic strength on the surface tension and nonequilibrium interfacial characteristics of poly(sodium styrenesulfonate)/dodecyltrimethylammonium bromide mixtures.

    Science.gov (United States)

    Ábrahám, Ágnes; Kardos, Attila; Mezei, Amália; Campbell, Richard A; Varga, Imre

    2014-05-06

    We rationalize the surface tension behavior and nonequilibrium interfacial characteristics of high molecular weight poly(sodium styrenesulfonate)/dodecyltrimethylammonium bromide (NaPSS/DTAB) mixtures with respect to the ionic strength. Excellent agreement is achieved between experimental data and our recent empirical model [Langmuir 2013, 29, 11554], which is based on the lack of colloidal stability of bulk aggregates in the phase separation region and has no free fitting parameters. We show that the size of a surface tension peak positioned at the edge of the phase separation region can be suppressed by the addition of inert electrolyte, which lowers the critical micelle concentration in relation to the phase separation region. Such manipulation of the peak is possible for the 100 ppm NaPSS/DTAB system because there is a high free surfactant concentration in the phase separation region. The close agreement of our model with the experimental data of samples in the phase separation region with respect to the ionic strength indicates that the surface tension behavior can be rationalized in terms of comprehensive precipitation regardless of whether there is a peak or not. The time scale of precipitation for the investigated system is on the order of one month, which emphasizes the need to understand the dynamic changes in the state of bulk aggregation in order to rationalize the surface properties of strongly interacting mixtures; steady state surface properties measured in the interim period will represent samples far from equilibrium. We show also that the surface properties of samples of low ionic strength outside the equilibrium phase separation region can be extreme opposites depending on the sample history, which is attributed to the generation of trapped nonequilibrium states. This work highlights the need to validate the underlying nature of oppositely charged polyelectrolyte/surfactant systems prior to the interpretation of experimental data within an

  4. Calcium Hypochlorite Solutions: Evaluation of Surface Tension and Effect of Different Storage Conditions and Time Periods over pH and Available Chlorine Content.

    Science.gov (United States)

    Leonardo, Natália Gomes e Silva; Carlotto, Israel Bangel; Luisi, Simone Bonato; Kopper, Patrícia Maria Poli; Grecca, Fabiana Soares; Montagner, Francisco

    2016-04-01

    The aim of this study was to evaluate the pH and the available chlorine content from sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca[OCl]2) solutions stored in different conditions and time periods and the surface tension of Ca(OCl)2 solutions in comparison with NaOCl. Solutions at 0.5%, 1%, 2.5%, and 5.25% concentrations were prepared. The pH level and the available chlorine content of freshly prepared solutions and solutions stored for 30, 60, and 90 days at 25°C, 4°C, or 37°C were evaluated in a digital pH meter and by titration, respectively. Surface tension was tested using a Du Nouy tensiometer (Sigma 702, Force Tensiometer; Attension, Espoo, Finland). Descriptive and inferential statistical analyses were performed. A precipitate formed by 2.5% and 5.25% Ca(OCl)2 solutions was observed. Ca(OCl)2 showed a higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 had a decrease in the available chlorine content when compared with freshly prepared solutions; 0.5% and 1% NaOCl tend to have a lower pH compared with 0.5% and 1% Ca(OCl)2. NaOCl, 5.25%, showed higher pH compared with 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentrations tend to show a reduced pH level, whereas 2.5% and 5.25% solutions showed an increase in pH. The heat contributed to the instability of the solutions. NaOCl showed lower surface tension values than Ca(OCl)2. Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl but have a higher surface tension than NaOCl. Regarding the available chlorine content, these solutions tend to be stable to 30 days of storage when kept at 4°C or at 25°C. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Abolishing the maximum tension principle

    Directory of Open Access Journals (Sweden)

    Mariusz P. Da̧browski

    2015-09-01

    Full Text Available We find the series of example theories for which the relativistic limit of maximum tension Fmax=c4/4G represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.

  6. Tensions to Frictions?

    DEFF Research Database (Denmark)

    Stein, Mari-Klara; Lim, Eric T. K.; Tan, Chee-Wee

    2014-01-01

    more value to all members collectively whenever each individual member participates more actively. This example also highlights the importance of usage effectiveness – the rather commonsense, yet often explicitly unexamined, idea that IT systems are not used for their own sake, but to attain relevant...

  7. Effects of streptozotocin-induced diabetes on the pharmacology of rat conduit and resistance intrapulmonary arteries

    Directory of Open Access Journals (Sweden)

    Howarth Frank C

    2009-01-01

    Full Text Available Abstract Background Poor control of blood glucose in diabetes is known to promote vascular dysfunction and hypertension. Diabetes was recently shown to be linked to an increased prevalence of pulmonary hypertension. The aim of this study was to determine how the pharmacological reactivity of intrapulmonary arteries is altered in a rat model of diabetes. Methods Diabetes was induced in rats by the β-cell toxin, streptozotocin (STZ, 60 mg/kg, and isolated conduit and resistance intrapulmonary arteries studied 3–4 months later. Isometric tension responses to the vasoconstrictors phenylephrine, serotonin and PGF2α, and the vasodilators carbachol and glyceryl trinitrate, were compared in STZ-treated rats and age-matched controls. Results STZ-induced diabetes significantly blunted the maximum response of conduit, but not resistance pulmonary arteries to phenylephrine and serotonin, without a change in pEC50. Agonist responses were differentially reduced, with serotonin (46% smaller affected more than phenylephrine (32% smaller and responses to PGF2α unaltered. Vasoconstriction caused by K+-induced depolarisation remained normal in diabetic rats. Endothelium-dependent dilation to carbachol and endothelium-independent dilation to glyceryl trinitrate were also unaffected. Conclusion The small resistance pulmonary arteries are relatively resistant to STZ-induced diabetes. The impaired constrictor responsiveness of conduit vessels was agonist dependent, suggesting possible loss of receptor expression or function. The observed effects cannot account for pulmonary hypertension in diabetes, rather the impaired reactivity to vasoconstrictors would counteract the development of pulmonary hypertensive disease.

  8. CALCULATION OF TENSION FORCE OF BELT CONVEYOR

    OpenAIRE

    Ismet Ibishi; Ahmet Latifi; Gzim Ibishi; Kadri Sejdiu; Melihate Shala-Galica; Bekim Latifi

    2012-01-01

    In this paper is done the explanation on tension fashion of the belt conveyor which is employed in Kosovo Energy Corporation – KEK, for coal transportation to provide electric power plant. The aim of the paper enables to recognize tension forces not to pass with deformation of belt so that this problem will damage the workingprocess. Work principle is based on initial tension and tension during working process. The fact is known that the tension starts from the carriage on the way to tension ...

  9. Surface Tension of Ab Initio Liquid Water at the Water-Air Interface

    CERN Document Server

    Nagata, Yuki; Bonn, Mischa; Kühne, Thomas D

    2016-01-01

    We report calculations of the surface tension of the water-air interface using ab initio molecular dynamics (AIMD) simulations. We investigate the simulation cell size dependence of the surface tension of water from force field molecular dynamics (MD) simulations, which show that the calculated surface tension increases with increasing simulation cell size, thereby illustrating that a correction for finite size effects is required for the small system used in the AIMD simulation. The AIMD simulations reveal that the double-{\\xi} basis set overestimates the experimentally measured surface tension due to the Pulay stress, while the triple and quadruple-{\\xi} basis sets give similar results. We further demonstrate that the van der Waals corrections critically affect the surface tension. AIMD simulations without the van der Waals correction substantially underestimate the surface tension, while van der Waals correction with the Grimme's D2 technique results in the value for the surface tension that is too high. T...

  10. Core vs. Bulk Samples in Soil-Moisture Tension Analyses

    Science.gov (United States)

    Walter M. Broadfoot

    1954-01-01

    The usual laboratory procedure in determining soil-moisture tension values is to use "undisturbed" soil cores for tensions up to 60 cm. of water and bulk soil samples for higher tensions. Low tensions are usually obtained with a tension table and the higher tensions by use of pressure plate apparatus. In tension analysis at the Vicksburg Infiltration Project...

  11. Surface tension of ab initio liquid water at the water-air interface.

    Science.gov (United States)

    Nagata, Yuki; Ohto, Tatsuhiko; Bonn, Mischa; Kühne, Thomas D

    2016-05-28

    We report calculations on the surface tension of the water-air interface using ab initio molecular dynamics (AIMD) simulations. We investigate the influence of the cell size on surface tension of water from force field molecular dynamics simulations. We find that the calculated surface tension increases with increasing simulation cell size, thereby illustrating that a correction for finite size effects is essential for small systems that are customary in AIMD simulations. Moreover, AIMD simulations reveal that the use of a double-ζ basis set overestimates the experimentally measured surface tension due to the Pulay stress while more accurate triple and quadruple-ζ basis sets give converged results. We further demonstrate that van der Waals corrections critically affect the surface tension. AIMD simulations without the van der Waals correction substantially underestimate the surface tension while the van der Waals correction with the Grimme's D2 technique results in a value for the surface tension that is too high. The Grimme's D3 van der Waals correction provides a surface tension close to the experimental value. Whereas the specific choices for the van der Waals correction and basis sets critically affect the calculated surface tension, the surface tension is remarkably insensitive to the details of the exchange and correlation functionals, which highlights the impact of long-range interactions on the surface tension. Our simulated values provide important benchmarks, both for improving van der Waals corrections and AIMD simulations of aqueous interfaces.

  12. Effect of nitric oxide blockade by NG-nitro-L-arginine on cerebral blood flow response to changes in carbon dioxide tension

    DEFF Research Database (Denmark)

    Wang, Qian; Paulson, O B; Lassen, N A

    1992-01-01

    , intracarotid infusion of 1.5, or 7.5, or 30 mg/kg NOLAG induced a dose-dependent increase of arterial blood pressure and a decrease of normocapnic CBF from 85 +/- 10 to 78 +/- 6, 64 +/- 5, and 52 +/- 5 ml 100 g-1 min-1, respectively. This effect lasted for at least 2 h. Raising PaCO2 from a control level of 40...... pressure to the same level as the highest dose of NOLAG did not affect the CBF response to hypercapnia. L-Arginine significantly prevented the effect of NOLAG on normocapnic CBF as well as blood pressure and also abolished its inhibitory effect on hypercapnic CBF. D-Arginine had no such effect. Decreasing...... to 68 mm Hg increased CBF to 230 +/- 27 ml 100 g-1 min-1, corresponding to a percentage CBF response (CO2 reactivity) of 3.7 +/- 0.6%/mm Hg PaCO2 in saline-treated rats. NOLAG attenuated this reactivity by 32, 49, and 51% at the three-dose levels. Hypercapnia combined with angiotensin to raise blood...

  13. Antihypertensive effect of allicin in dexamethasone-induced hypertensive rats

    Directory of Open Access Journals (Sweden)

    Harikesh Dubey

    2017-03-01

    Conclusion: This result suggests antihypertensive effects of allicin in dexamethasone induced hypertension. However, further studies are needed to explore the detailed mechanism of antihypertensive effect of allicin.

  14. Overlapped optics induced perfect coherent effects

    Science.gov (United States)

    Li, Jian Jie; Zang, Xiao Fei; Mao, Jun Fa; Tang, Min; Zhu, Yi Ming; Zhuang, Song Lin

    2013-12-01

    For traditional coherent effects, two separated identical point sources can be interfered with each other only when the optical path difference is integer number of wavelengths, leading to alternate dark and bright fringes for different optical path difference. For hundreds of years, such a perfect coherent condition seems insurmountable. However, in this paper, based on transformation optics, two separated in-phase identical point sources can induce perfect interference with each other without satisfying the traditional coherent condition. This shifting illusion media is realized by inductor-capacitor transmission line network. Theoretical analysis, numerical simulations and experimental results are performed to confirm such a kind of perfect coherent effect and it is found that the total radiation power of multiple elements system can be greatly enhanced. Our investigation may be applicable to National Ignition Facility (NIF), Inertial Confined Fusion (ICF) of China, LED lighting technology, terahertz communication, and so on.

  15. Esomeprazole induced galactorrhea: a novel side effect.

    Science.gov (United States)

    Pipaliya, Nirav; Solanke, Dattatray; Rathi, Chetan; Patel, Ruchir; Ingle, Meghraj; Sawant, Prabha

    2016-02-01

    Proton pump inhibitors (PPIs) are one of the most frequently prescribed medications across the globe. Esomeprazole is the S-isomer of omeprazole, and it is currently the most widely prescribed PPI. The safety profile of esomeprazole is extremely favorable with only minor side effects, like headache and diarrhea, that are encountered in day to day practice. We report a case of a young female with symptoms of gastroesophageal reflux disease who developed galactorrhea after starting esomeprazole therapy. Resolution of galactorrhea after stopping the drug and self-rechallenge by the patient herself with reappearance of galactorrhea confirmed the culprit to be esomeprazole only. We postulate that esomeprazole may have a mild inhibitory effect on CYP3A4, which leads to decreased metabolism of estrogen, thereby increasing serum estrogen levels. Estrogen causes stimulation and production of prolactin release, which results in development of galactorrhea. This is the first case of esomeprazole induced galactorrhea, to the best of our knowledge.

  16. Actin cortex architecture regulates cell surface tension.

    Science.gov (United States)

    Chugh, Priyamvada; Clark, Andrew G; Smith, Matthew B; Cassani, Davide A D; Dierkes, Kai; Ragab, Anan; Roux, Philippe P; Charras, Guillaume; Salbreux, Guillaume; Paluch, Ewa K

    2017-06-01

    Animal cell shape is largely determined by the cortex, a thin actin network underlying the plasma membrane in which myosin-driven stresses generate contractile tension. Tension gradients result in local contractions and drive cell deformations. Previous cortical tension regulation studies have focused on myosin motors. Here, we show that cortical actin network architecture is equally important. First, we observe that actin cortex thickness and tension are inversely correlated during cell-cycle progression. We then show that the actin filament length regulators CFL1, CAPZB and DIAPH1 regulate mitotic cortex thickness and find that both increasing and decreasing thickness decreases tension in mitosis. This suggests that the mitotic cortex is poised close to a tension maximum. Finally, using a computational model, we identify a physical mechanism by which maximum tension is achieved at intermediate actin filament lengths. Our results indicate that actin network architecture, alongside myosin activity, is key to cell surface tension regulation.

  17. Light Scattering by Surface Tension Waves.

    Science.gov (United States)

    Weisbuch, G.; Garbay, F.

    1979-01-01

    This simple and inexpensive experiment is an illustration of the physical concepts of interaction between light and surface tension waves, and provides a new method of measuring surface tension. (Author/GA)

  18. SURFACE TENSION TECHNIQUES FOR MOLTEN SALTS

    Science.gov (United States)

    Some 200 surface tension determinations were made on 107 single-salt melts using eight experimental techniques. From a consideration of the... surface tension range of applicability and temperature limitation for these techniques are briefly considered.

  19. A TOGgle for Tension at Kinetochores

    OpenAIRE

    Cheerambathur, Dhanya K.; Prevo, Bram; Desai, Arshad

    2016-01-01

    Differential stability of kinetochore-microtubule attachments at low versus high tension is critical for accurate chromosome segregation. Miller et al. find that a TOG domain microtubule-binding protein imparts intrinsic tension selectivity to kinetochore-microtubule attachments.

  20. Phenylephrine Decreases Vascular Tension in Goat Arteries in Specific Circumstances.

    Directory of Open Access Journals (Sweden)

    Renu R Raj

    Full Text Available Phenylephrine (PE causes vasoconstriction through alpha adrenergic receptors. PE-induced vasodilatation has also been reported earlier in pre-constricted vessels. Here we demonstrate in spiral strips of goat arteries that addition of PE can decrease tone even from base-line levels (i.e. not pre-constricted and show that this process requires nitric oxide (NO and alpha adrenergic stimulation, but is cGMP-independent. Under control conditions, PE caused vasoconstriction, but under conditions where NO levels are higher, as with L-Arginine or sodium nitroprusside, PE decreased vessel tension. L-Arginine/PE combination was not able to decrease tension when alpha adrenoceptors were blocked with Phentolamine or endothelial nitric oxide synthase (eNOS was blocked with Nω-Nitro-L-arginine (L-NNA. Propranolol, a beta blocker, was unable to prevent the reduction in tension by the L-Arginine/PE combination. Adrenaline and noradrenaline (and not isoproterenol also reduced vessel tension in the presence of L-Arginine. Even when NO levels were not enhanced, relieving NO from having to stimulate the enzyme soluble guanylyl cyclase (sGC (either by using sGC blockers, namely ODQ or methylene blue, or by enhancing cGMP levels (with sildenafil which by negative feedback probably inhibits sGC led to PE-induced reduction of vascular tension. PMA-phorbol myristate acetate-an agonist which stimulates Protein Kinase C was able to prevent the ability of PE to reduce vascular tension in a high NO environment. Our conclusion is that PE reduces vascular tension through alpha adrenoceptors if there is excess NO availability to activate a putative pathway. Though the reduction of vessel tone by PE is dependent on NO, it is independent of cGMP. Prior treatment with PMA or PE itself can prevent further PE-induced reduction of tension in a high NO environment. The results here suggest, counter-intuitively, that alpha blockers may be of help in the treatment of septic shock

  1. Intraoperative Development of Tension Pneumocephalus in a ...

    African Journals Online (AJOL)

    Included is a literature review of studies discussing the role of N2O in the development of tension pneumocephalus. N2O is associated with tension pneumocephalus especially in the setting of preexisting pneumocephalus. Tension pneumocephalus can manifest as Cushing response and immediate decompression is ...

  2. Effect of Second-Order and Fully Nonlinear Wave Kinematics on a Tension-Leg-Platform Wind Turbine in Extreme Wave Conditions: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pegalajar-Jurado, Antonio [Technical University of Denmark; Borg, Michael [Technical University of Denmark; Bredmose, Henrik [Technical University of Denmark

    2017-08-02

    In this study, we assess the impact of different wave kinematics models on the dynamic response of a tension-leg-platform wind turbine. Aero-hydro-elastic simulations of the floating wind turbine are carried out employing linear, second-order, and fully nonlinear kinematics using the Morison equation for the hydrodynamic forcing. The wave kinematics are computed from either theoretical or measured signals of free-surface elevation. The numerical results from each model are compared to results from wave basin tests on a scaled prototype. The comparison shows that sub and superharmonic responses can be introduced by second-order and fully nonlinear wave kinematics. The response at the wave frequency range is better reproduced when kinematics are generated from the measured surface elevation. In the future, the numerical response may be further improved by replacing the global, constant damping coefficients in the model by a more detailed, customizable definition of the user-defined numerical damping.

  3. Effect of Second-Order and Fully Nonlinear Wave Kinematics on a Tension-Leg-Platform Wind Turbine in Extreme Wave Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pegalajar-Jurado, Antonio [Technical University of Denmark; Borg, Michael [Technical University of Denmark; Bredmose, Henrik [Technical University of Denmark

    2017-06-03

    In this study, we assess the impact of different wave kinematics models on the dynamic response of a tension-leg-platform wind turbine. Aero-hydro-elastic simulations of the floating wind turbine are carried out employing linear, second-order, and fully nonlinear kinematics using the Morison equation for the hydrodynamic forcing. The wave kinematics are computed from either theoretical or measured signals of free-surface elevation. The numerical results from each model are compared to results from wave basin tests on a scaled prototype. The comparison shows that sub and superharmonic responses can be introduced by second-order and fully nonlinear wave kinematics. The response at the wave frequency range is better reproduced when kinematics are generated from the measured surface elevation. In the future, the numerical response may be further improved by replacing the global, constant damping coefficients in the model by a more detailed, customizable definition of the user-defined numerical damping.

  4. Rein tension acceptance in young horses in a voluntary test situation.

    Science.gov (United States)

    Christensen, J W; Zharkikh, T L; Antoine, A; Malmkvist, J

    2011-03-01

    During riding, horses are frequently exposed to pressure from the rider, e.g. through the bit and reins, but few studies have investigated at which point rein tension becomes uncomfortable for the horse. To investigate how much rein tension young inexperienced horses are willing to accept in order to obtain a food reward; whether the tension acceptance changes during 3 consecutive test days; and whether rein tension correlates with the expression of conflict behaviour and heart rate. Pressure-naïve horses will apply only little rein tension in the first voluntary trial, but their acceptance will gradually increase. High levels of rein tension will lead to expression of conflict behaviour and increases in heart rate. Fifteen 2-year-old, bridle-naïve mares were encouraged to stretch their head forward (across a 0.95 m high metal bar) to obtain a food reward in a voluntary test situation. On each test day, each horse was exposed to 2 control sessions (loose reins), an intermediate and a short rein session (1 min/session). Rein tension, heart rate and behaviour were recorded. The horses applied significantly more tension on the first day (mean rein tension: 10.2 N), compared to the second and third test day (Day 2: 6.0 and Day 3: 5.7 N). The horses showed significantly more conflict behaviour in the short rein treatment. There was no treatment effect on heart rate. The horses applied the highest rein tension on the first day, and apparently learned to avoid the tension, rather than habituate to it. Rein tension correlated with expression of conflict behaviour, indicating that the horses found the tension aversive. Further studies should focus on the correlation between rein tension and conflict behaviour in ridden horses. © 2010 EVJ Ltd.

  5. The Plastic Tension Field Method

    DEFF Research Database (Denmark)

    Hansen, Thomas

    2005-01-01

    . The emphasis is attached to the presentation of a design method based on the diagonal tension field theory. Also, how to determine the load-carrying capacity of a given steel plate girder with transverse web stiffeners, is briefly presented. The load-carrying capacity may be predicted by applying both......This paper describes a calculation method for steel plate girders with transverse web stiffeners subjected to shear. It may be used for predicting the failure load or, as a design method, to determine the optimal amount of internal web stiffeners. The new method is called the plastic tension field...... method. The method is based on the theory of plasticity and is analogous to the so-called diagonal compression field method developed for reinforced concrete beams with transverse stirrups, which is adopted in the common European concrete code (Eurocode 2). Many other theories have been developed...

  6. The fracture toughness of small animal cortical bone measured using arc-shaped tension specimens: Effects of bisphosphonate and deproteinization treatments.

    Science.gov (United States)

    Hunckler, Michael D; Chu, Ethan D; Baumann, Andrew P; Curtis, Tyler E; Ravosa, Matthew J; Allen, Matthew R; Roeder, Ryan K

    2017-12-01

    Small animal models, and especially transgenic models, have become widespread in the study of bone mechanobiology and metabolic bone disease, but test methods for measuring fracture toughness on multiple replicates or at multiple locations within a single small animal bone are lacking. Therefore, the objective of this study was to develop a method to measure cortical bone fracture toughness in multiple specimens and locations along the diaphysis of small animal bones. Arc-shaped tension specimens were prepared from the mid-diaphysis of rabbit ulnae and loaded to failure to measure the radial fracture toughness in multiple replicates per bone. The test specimen dimensions, crack length, and maximum load met requirements for measuring the plane strain fracture toughness. Experimental groups included a control group, bisphosphonate treatment group, and an ex vivo deproteinization treatment following bisphosphonate treatment (5 rabbits/group and 15 specimens/group). The fracture toughness of ulnar cortical bone from rabbits treated with zoledronic acid for six months exhibited no difference compared with the control group. Partially deproteinized specimens exhibited significantly lower fracture toughness compared with both the control and bisphosphonate treatment groups. The deproteinization treatment increased tissue mineral density (TMD) and resulted in a negative linear correlation between the measured fracture toughness and TMD. Fracture toughness measurements were repeatable with a coefficient of variation of 12-16% within experimental groups. Retrospective power analysis of the control and deproteinization treatment groups indicated a minimum detectable difference of 0.1MPa·m1/2. Therefore, the overall results of this study suggest that arc-shaped tension specimens offer an advantageous new method for measuring the fracture toughness in small animal bones. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Crystallographic Analysis of Fatigue Crack Initiation Behavior in Coarse-Grained Magnesium Alloy Under Tension-Tension Loading Cycles

    Science.gov (United States)

    Tamada, Kazuhiro; Kakiuchi, Toshifumi; Uematsu, Yoshihiko

    2017-07-01

    Plane bending fatigue tests are conducted to investigate fatigue crack initiation mechanisms in coarse-grained magnesium alloy, AZ31, under the stress ratios R = -1 and 0.1. The initial crystallographic structures are analyzed by an electron backscatter diffraction method. The slip or twin operation during fatigue tests is identified from the line angle analyses based on Euler angles of the grains. Under the stress ratio R = -1, relatively thick tension twin bands are formed in coarse grains. Subsequently, compression twin or secondary pyramidal slip operates within the tension twin band, resulting in the fatigue crack initiation. On the other hand, under R = 0.1 with tension-tension loading cycles, twin bands are formed on the specimen surface, but the angles of those bands do not correspond to tension twins. Misorientation analyses of c-axes in the matrix grain and twin band reveal that double twins are activated. Under R = 0.1, fatigue crack initiates along the double twin boundaries. The different manners of fatigue crack initiation at R = -1 and 0.1 are related to the asymmetricity of twining under tension and compression loadings. The fatigue strengths under different stress ratios cannot be estimated by the modified Goodman diagram due to the effect of stress ratio on crack initiation mechanisms.

  8. Robust Tensioned Kevlar Suspension Design

    Science.gov (United States)

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  9. Wavelength mismatch effect in electromagnetically induced absorption

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Vineet [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Wasan, Ajay [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Natarajan, Vasant [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2016-07-15

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  10. Tension and depression in women--the place of hormone therapy.

    Science.gov (United States)

    Taylor, R W

    1980-09-01

    Discussion focused on the use of hormone therapy for treating tension and depression experienced by women at various times during their life cycle. Teenagers frequently experience mood changes and discomfort during the early menstrual years. Most of these problems gradually disappear without treatment. In cases of severe dysmenorrhea, conventional estrogen and progestogen pills can be administered. Many women experience tension or depression during pregnancy. These feelings are usually induced by ambivalent feelings toward the pregnancy, concern about the pregnancy outcome, or fear of labor. Reassurance is the only therapy needed by most of these women. Neurotic puerperal reactions are rare but when they occur they are usually mild and disappear quickly. Prostaglandins are sometimes used to treat puerperal psychosis but prompt psychiatric care is probably more effective. About 10% of all females suffer from premenstrual syndrome. Dydrogesterone is effective in treating about 70% of these cases. Pyridoxine relieves symptoms in about 50% of these patients. Many women experience postmenopausal depression. Depression at that time can be induced by physiological changes; however, women during that stage of life may also be suffering from externally induced depression. If the depression has a physiological basis, estrogen replacement therapy is usually helpful. About 6% of the women who use oral contraceptives experience depression. These symptoms are sometimes relieved by administering pyridoxine or by taking a weak progestogen during the last week of pill taking.

  11. Field Induced Memory Effects in Random Nematics

    Directory of Open Access Journals (Sweden)

    Amid Ranjkesh

    2014-01-01

    Full Text Available We studied numerically external field induced memory effects in randomly perturbed nematic liquid crystals. Random anisotropy nematic-type lattice model was used. The impurities imposing orientational disorder were randomly spatially distributed with the concentration p below the percolation threshold. Simulations were carried for finite temperatures, where we varied p, interaction strength between LC molecules, and impurities and external field B. In the {B,T} plane we determined lines separating short range—quasi long range and quasi long range—long range order. Furthermore, crossover regime separating external field and random field dominated regime was estimated. We calculated remanent nematic ordering in samples at B=0 as a function of the previously experienced external field strength B.

  12. Dynamics of surface tension driven mixing of an alcohol droplet with water

    Science.gov (United States)

    Dandekar, Raj; Pant, Anurag; Puthenveettil, Baburaj

    2016-11-01

    We study the flow induced by the surface tension driven spreading of an ethanol droplet of radius rd on the surface of a 5mm water layer, visualizing the flow using aluminium flakes on the surface of the water layer with backlighting and high speed imaging. The concentration of tracer aluminium particles was found to have no effect on the scaling law for spreading.The drop,when brought in contact with the water surface causes a local depression in surface tension ,resulting in a thin circular region to expand radially outwards.We observe that the dimensionless radius of the expanding front (r* =r/rd) scales with the dimensionless time (t* = μ rd/ Δγ) , as r* t*1/4,where μ is the viscosity of water and Δγ is the surface tension difference between water and the ethanol droplet.A scaling analysis taking the viscous and the marangoni forces into account explains the observed scaling law.Our observations differ from that in the case of continuous alcohol supply where the observed scaling law is r* t*1/2. The expanding front radius reaches a maximum value and then decreases with time.

  13. Effect of loading speed on the stress-induced magnetic behavior of ferromagnetic steel

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Sheng, E-mail: longtubao@zju.edu.cn; Gu, Yibin; Fu, Meili; Zhang, Da; Hu, Shengnan

    2017-02-01

    The primary goal of this research is to investigate the effect of loading speed on the stress-induced magnetic behavior of a ferromagnetic steel. Uniaxial tension tests on Q235 steel were carried out with various stress levels under different loading speeds. The variation of the magnetic signals surrounding the tested specimen was detected by a fluxgate magnetometer. The results indicated that the magnetic signal variations depended not only on the tensile load level but on the loading speed during the test. The magnetic field amplitude seemed to decrease gradually with the increase in loading speed at the same tensile load level. Furthermore, the evolution of the magnetic reversals is also related to the loading speed. Accordingly, the loading speed should be considered as one of the influencing variables in the Jies-Atherton model theory of the magnetomechanical effect. - Highlights: • Magnetic behaviors induced by different loading speeds were investigated. • Loading speed imposes strong impact on the variation of the magnetic field signals. • The magnetic field amplitude reduces gradually with the increasing loading speed. • The Jies-Atherton model theory should consider the effect of loading speed.

  14. PDT-induced in vitro bystander effect

    Science.gov (United States)

    Olivier, David; Douilard, Samuel; Patrice, Thierry

    2009-06-01

    The mechanisms of Photodynamic therapy (PDT) include singlet oxygen and reactive oxygen species (ROS) production that damage tumor cells and vasculature. The resulting effect is a balance between photo-oxidations via primary or secondary ROS and scavenging activity. Sensitizers distribute in the extra-cellular space before and during cell sensitization, suggesting that PDT could act directly on cell structures and on extra-cellular compartments, including sera. In this paper we endeavored to determine whether the application of PDT to culture media could have an effect on cell survival. Culture media (RPMI supplemented with Fetal Calf Serum (FCS)) was incubated with Rose Bengal (RB) and irradiated before being added to cells for various times of contact, as a replacement for untreated media. Treatedmedia reduced cell survival by up to 40% after 30 min of contact for 10 μg/mL of RB and 20 J/cm2. This effect was RB or light dose-dependent. The survival reduction observed when adding treated-media was more pronounced when cell doubling time was shorter. Analysis of ROS or peroxide production in treated-media revealed a long-lasting oxidizing activity. Our findings support the hypothesis of a ROS or peroxide-mediated, PDT-induced, delayed cell toxicity

  15. Surface tension in microsystems engineering below the capillary length

    CERN Document Server

    Lambert, Pierre

    2014-01-01

    This book describes how surface tension effects can be used by engineers to provide mechanical functions in miniaturized products (<1 mm). Even if precursors of this field such as Jurin or Laplace already date back to the 18th century, describing surface tension effects from a mechanical perspective is very recent. The originality of this book is to consider the effects of capillary bridges on solids, including forces and torques exerted both statically and dynamically by the liquid along the 6 degrees-of-freedom. It provides a comprehensive approach to various applications, such as capillary adhesion (axial force), centering force in packaging and micro-assembly (lateral force) and recent developments such as a capillary motor (torque). It devises how surface tension can be used to provide mechanical functions such as actuation (bubble-actuated compliant table), sealing and tightness, energy harvesting, nanodispending.

  16. Study of the function of sarcoplasmic reticulum of vascular smooth muscle during activation due to depolarization-induced calcium influx

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, K.S.

    1987-01-01

    The role of sarcoplasmic reticulum (SR) in vascular smooth muscle was evaluated with respect to regulation of myoplasmic Ca{sup 2+} during the Ca{sup 2+} entry induced by depolarization. Calcium agonist, Bay K8644, stimulated Ca{sup 2+} influx as well as tension in physiological salt solution, (PSS) in contrast to the priming effects due to the depolarization originally reported. Disparity, however, was found between the Ca{sup 2+} entered and tension developed. Correlation between the tension and {sup 45}Ca influx showed a typical threshold phenomenon; the basal Ca{sup 2+} influx can be raised to a certain level (25%) without tension induction, after which a minor increase in Ca{sup 2+} influx produced significant tension. This subthreshold Ca{sup 2+} influx was found accumulated in the caffeine-sensitive Ca stores, the SR. This confirmed the dependency of tension on the rate of Ca{sup 2+} entry demonstrated by a previous report.

  17. Small membranes under negative surface tension.

    Science.gov (United States)

    Avital, Yotam Y; Farago, Oded

    2015-03-28

    We use computer simulations and a simple free energy model to study the response of a bilayer membrane to the application of a negative (compressive) mechanical tension. Such a tension destabilizes the long wavelength undulation modes of giant vesicles, but it can be sustained when small membranes and vesicles are considered. Our negative tension simulation results reveal two regimes-(i) a weak negative tension regime characterized by stretching-dominated elasticity and (ii) a strong negative tension regime featuring bending-dominated elastic behavior. This resembles the findings of the classic Evans and Rawicz micropipette aspiration experiment in giant unilamellar vesicles (GUVs) [E. Evans and W. Rawicz, Phys, Rev. Lett. 64, 2094 (1990)]. However, in GUVs the crossover between the two elasticity regimes occurs at a small positive surface tension, while in smaller membranes it takes place at a moderate negative tension. Another interesting observation concerning the response of a small membrane to negative surface tension is related to the relationship between the mechanical and fluctuation tensions, which are equal to each other for non-negative values. When the tension decreases to negative values, the fluctuation tension γ drops somewhat faster than the mechanical tension τ in the small negative tension regime, before it saturates (and becomes larger than τ) for large negative tensions. The bending modulus exhibits an "opposite" trend. It remains almost unchanged in the stretching-dominated elastic regime, and decreases in the bending-dominated regime. Both the amplitudes of the thermal height undulations and the projected area variations diverge at the onset of mechanical instability.

  18. Anemonia sulcata toxin (ATX II) enhances spontaneous electrical activity and tension in chronically denervated rat diaphragm.

    Science.gov (United States)

    Ravens, U; Wiese, R

    1985-09-01

    In isolated strips of rat diaphragm denervated 9-21 days prior to experimentation, spontaneous action potentials were recorded extracellularly and twitch and resting tension were measured. The sea anemone toxin ATX II enhances the occurrence of spontaneous action potentials, increases resting tension and depresses twitch tension. These effects are essentially irreversible. In low sodium solution substituted with sucrose the effects of ATX II are attenuated, however, they fully develop upon return to normal sodium solution with a marked transient increase in the incidence of spontaneous action potentials and in resting tension. ATX II remains uneffective after pretreatment with tetrodotoxin. Reelevation of the extracellular sodium concentration after exposure to low sodium solution per se causes a marked increase in occurrence of fibrillation potentials, however the transient increase in resting tension was much smaller than in the presence of ATX II. Substitution of chloride with the impermeable anion methylsulphate enhances spontaneous activity and resting tension without an effect on twitch tension. Addition of ATX II elevates resting tension although the concomitant further increase in incidence of spontaneous action potentials is small. It is concluded that the increase in resting tension reflects a summation of the fibrillatory activity, but fibrillations become more effective when the preparations are exposed to ATX II. This finding points at the possible rôle of sodium ions in excitation contraction coupling of denervated skeletal muscle.

  19. A finite-volume HLLC-based scheme for compressible interfacial flows with surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Garrick, Daniel P. [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States); Owkes, Mark [Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT (United States); Regele, Jonathan D., E-mail: jregele@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States)

    2017-06-15

    Shock waves are often used in experiments to create a shear flow across liquid droplets to study secondary atomization. Similar behavior occurs inside of supersonic combustors (scramjets) under startup conditions, but it is challenging to study these conditions experimentally. In order to investigate this phenomenon further, a numerical approach is developed to simulate compressible multiphase flows under the effects of surface tension forces. The flow field is solved via the compressible multicomponent Euler equations (i.e., the five equation model) discretized with the finite volume method on a uniform Cartesian grid. The solver utilizes a total variation diminishing (TVD) third-order Runge–Kutta method for time-marching and second order TVD spatial reconstruction. Surface tension is incorporated using the Continuum Surface Force (CSF) model. Fluxes are upwinded with a modified Harten–Lax–van Leer Contact (HLLC) approximate Riemann solver. An interface compression scheme is employed to counter numerical diffusion of the interface. The present work includes modifications to both the HLLC solver and the interface compression scheme to account for capillary force terms and the associated pressure jump across the gas–liquid interface. A simple method for numerically computing the interface curvature is developed and an acoustic scaling of the surface tension coefficient is proposed for the non-dimensionalization of the model. The model captures the surface tension induced pressure jump exactly if the exact curvature is known and is further verified with an oscillating elliptical droplet and Mach 1.47 and 3 shock-droplet interaction problems. The general characteristics of secondary atomization at a range of Weber numbers are also captured in a series of simulations.

  20. Local deformation method for measuring element tension in space deployable structures

    Directory of Open Access Journals (Sweden)

    Belov Sergey

    2017-01-01

    Full Text Available The article describes the local deformation method to determine the tension of cord and thin membrane elements in space deployable structure as antenna reflector. Possible measuring instrument model, analytical and numerical solutions and experimental results are presented. The boundary effects on measurement results of metallic mesh reflector surface tension are estimated. The study case depicting non-uniform reflector surface tension is considered.

  1. Pre-tension generates strongly reversible adhesion of a spatula pad on substrate

    OpenAIRE

    Chen, Bin; Wu, Peidong; Gao, Huajian

    2008-01-01

    Motivated by recent studies on reversible adhesion mechanisms of geckos and insects, we investigate the effect of pre-tension on the orientation-dependent adhesion strength of an elastic tape adhering on a substrate. Our analysis shows that the pre-tension can significantly increase the peel-off force at small peeling angles while decreasing it at large peeling angles, leading to a strongly reversible adhesion. More interestingly, we find that there exists a critical value of pre-tension beyo...

  2. A space tethered towing method using tension and platform thrusts

    Science.gov (United States)

    Meng, Zhongjie; Wang, Bingheng; Huang, Panfeng

    2017-01-01

    Orbit maneuver via tether is a promising countermeasure for space debris removal and satellite orbit transfer. A space tethered towing method is explored that utilizes thrust to fulfill transfer and bounded tension to stabilize tether heading. For this purpose, a time-energy optimal orbit is designed by Gauss pseudospectral method. The theoretical attitude commands are obtained by equilibria analysis. An effective attitude control strategy is presented where the commands are optimized first and then feedback controller is designed. To deal with the underactuated problem with tension constraint, hierarchical sliding mode theory is employed and an adaptive anti-windup module is added to mitigate the actuator saturation. Simulation results show that the target is towed effectively by the thrusts, and a smooth tracking for the commands of tether length and in-plane tether heading is guaranteed by the bounded tension. In addition, the designed controller also presents appreciable robustness to model error and determination error.

  3. Reefing Line Tension in CPAS Main Parachute Clusters

    Science.gov (United States)

    Ray, Eric S.

    2013-01-01

    Reefing lines are an essential feature to manage inflation loads. During each Engineering Development Unit (EDU) test of the Capsule Parachute Assembly System (CPAS), a chase aircraft is staged to be level with the cluster of Main ringsail parachutes during the initial inflation and reefed stages. This allows for capturing high-quality still photographs of the reefed skirt, suspension line, and canopy geometry. The over-inflation angles are synchronized with measured loads data in order to compute the tension force in the reefing line. The traditional reefing tension equation assumes radial symmetry, but cluster effects cause the reefed skirt of each parachute to elongate to a more elliptical shape. This effect was considered in evaluating multiple parachutes to estimate the semi-major and semi-minor axes. Three flight tests are assessed, including one with a skipped first stage, which had peak reefing line tension over three times higher than the nominal parachute disreef sequence.

  4. Propagation of Financial Tensions from Developed Economies to Emerging Economies

    Directory of Open Access Journals (Sweden)

    Mihaela-Carmen MUNTEAN

    2011-03-01

    Full Text Available This paper aims to present the effect they have financial tensions in countries with developed economies on emerging economies. Because many economies have entered into recession, this has resulted in significant slowing of economic growth. The paper’s objectives are related to the presentation of the current global economic situation, the rapidity with which covered the entire world financial crisis. Also, there are presented the levels of development trade flows, financial and monetary, the financials tensions' effect in developed economies and emerging economies, financial ratios and analysis, their composition and relations between them. The methodologies used in this paper are based on economic analysis and a financial interpretation and econometric calculations of the propagation of financial tensions.

  5. Capsaicin and N-arachidonoyl-dopamine (NADA) decrease tension by activating both cannabinoid and vanilloid receptors in fast skeletal muscle fibers of the frog.

    Science.gov (United States)

    Trujillo, Xóchitl; Ortiz-Mesina, Mónica; Uribe, Tannia; Castro, Elena; Montoya-Pérez, Rocío; Urzúa, Zorayda; Feria-Velasco, Alfredo; Huerta, Miguel

    2015-02-01

    Previous studies have indicated that vanilloid receptor (VR1) mRNA is expressed in muscle fibers. In this study, we evaluated the functional effects of VR1 activation. We measured caffeine-induced contractions in bundles of the extensor digitorum longus muscle of Rana pipiens. Isometric tension measurements showed that two VR1 agonists, capsaicin (CAP) and N-arachidonoyl-dopamine (NADA), reduced muscle peak tension to 57 ± 4 % and 71 ± 3% of control, respectively. The effect of CAP was partially blocked by a VR1 blocker, capsazepine (CPZ), but the effect of NADA was not changed by CPZ. Because NADA is able to act on cannabinoid receptors, which are also present in muscle fibers, we tested the cannabinoid antagonist AM281. We found that AM281 antagonized both CAP and NADA effects. AM281 alone reduced peak tension to 80 ± 6 % of control. With both antagonists, the CAP effect was completely blocked, and the NADA effect was partially blocked. These results provide pharmacological evidence of the functional presence of the VR1 receptor in fast skeletal muscle fibers of the frog and suggest that capsaicin and NADA reduce tension by activating both cannabinoid and vanilloid receptors.

  6. Effect of culture at low oxygen tension on the expression of heat shock proteins in a panel of melanoma cell lines.

    Directory of Open Access Journals (Sweden)

    Christopher Shipp

    Full Text Available Tumours are commonly hypoxic and this can be associated with aggressive tumour type, metastasis and resistance to therapy. Heat shock proteins (hsps are induced in response to hypoxia, provide cancer cells with protection against tumour-associated stressors and chaperone oncoproteins that drive tumour proliferation. This study examined the effect of different oxygen concentrations on the expression of hsps in melanoma cell lines.Melanoma cell lines were cultured in 2% and 20% O(2. Expression of Hsp90, Hsp70, Hsp60, Hsp40 and Hsp32 proteins were determined by flow cytometry.Growth rates and viability were reduced in the majority of cell lines by culture in 2% O(2. Hsp expression was different in 2% compared to 20% O(2 and changes in Hsp90 expression correlated with cell line generation time (P<0.005 and viability (P<0.01. Greater total hsp expression correlated with improved viability in 2% but not 20% O(2 (P<0.05. Relative expression of the different hsps was consistent across cell lines and each correlated with the others (P = 0.0001 but not with Hsp32. Hsp expression was inversely correlated with cell line adhesion to laminin as well as collagen type IV and Breslow depth of the original primary tumour tissue (P<0.05, but not with Clark level or patient survival. All five hsps were identified on the cell surface.Culture in 2% O(2 variably altered hsp expression in a panel of melanoma cell lines. Hsp expression was associated with certain cell line characteristics and clinical parameters of the originating tumour.

  7. Update on normal tension glaucoma

    Directory of Open Access Journals (Sweden)

    Jyotiranjan Mallick

    2016-01-01

    Full Text Available Normal tension glaucoma (NTG is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases, systemic calcium channel blockers (such as nifedipine and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG.

  8. The effects of macromolecular and serum supplements and oxygen tension during bovine in vitro procedures on kinetics of oocyte maturation and embryo development.

    Science.gov (United States)

    Mingoti, Gisele Zoccal; Castro, Viviane Sggobi Dias Caiado; Méo, Simone Cristina; Sá Barretto, Letícia Siqueira; Garcia, Joaquim Mansano

    2011-06-01

    Aiming to standardize in vitro production of bovine embryos and to obtain supplements to replace serum in culture media, this study evaluated the nuclear maturation kinetics and embryonic development in bovine after in vitro maturation (IVM) and culture (IVC) with several macromolecules (animal origin: bovine serum albumin (BSA), fetal calf serum (FCS); synthetic: polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), Ficoll, and Knockout) at two oxygen tensions (20% and 5% O(2)). Regarding nuclear kinetics, neither the presence of the expected stage (metaphase I, transition anaphase to telophase, and metaphase II) at each evaluation moment (6, 18, and 24 h after IVM, respectively) nor the accelerated polar body emission (at 18 h after IVM) related developmental competence to blastocyst stage when different supplements were compared. Independently of supplement, cleavage rates at 20% O(2) (61.6-79.2%) were higher than at 5% O(2) (38.9-58.7%). At 20% O(2), higher blastocyst and hatching rates, respectively, were obtained in treatments BSA, FCS, Knockout, and control group (IVM with FCS and IVC with BSA + FCS, 14.0-23.5% and 6.8-15.4%) in comparison to PVA, PVP, and Ficoll (0%). The same was observed at 5% O(2) for blastocyst rates with BSA, FCS, Knockout, and control (5.4-16.8%) and for hatching rates with BSA, FCS, and control (2.0-11.1%). We can conclude that producing bovine embryos at 20% O(2) during the entire IVP process resulted in higher developmental rates than at 5% O(2). In addition, while defined macromolecules PVA, PVP, and Ficoll were not suitable for embryonic development, the synthetic serum Knockout was able to replace serum and albumin for IVP in bovine at 20% O(2).

  9. Effect of soil-water tension on herbaceous cotton yield Efeito de tensões de água no solo sobre o rendimento do algodoeiro herbáceo

    Directory of Open Access Journals (Sweden)

    Francisco Assis de Oliveira

    1999-10-01

    Full Text Available A field experiment was conducted during two years, 1990/91, in an alluvial soil, in the State of Paraíba, Brazil, to study the effect of the levels of soil-water tension, 50, 100, 200, 300, 400 and 600 kPa, at 20 cm depth, on upland cotton (Gossypium hirsutum L.r. latifolium Hutch, cv. CNPA-6H yield. The experimental design was a complete randomized block with six treatments and four repetitions. There was an effect of the treatments on plant height, leaf area index and cotton yield, but the precocity index was not modified. Water should be applied when the soil-water tension, measured at 20 cm depth, reaches values around 200 kPa. There was a quadratic (R² = 0.893** response of cotton yields to soil water tension, with the maximum when water was applied at 52% of soil water depletion.Durante dois anos, 1990/91, em solo aluvial, no município de Sousa, PB, estudou-se, em condições de irrigação por sulco, o efeito das tensões de água no solo a 50, 100, 200, 300, 400 e 600 kPa, na profundidade de 20 cm, sobre o rendimento do algodoeiro herbáceo (Gossypium hirsutum L.r. latifolium Hutch, cv. CNPA-6H. Adotou-se o delineamento experimental de blocos ao acaso com quatro repetições. Os resultados mostraram que houve efeito significativo dos tratamentos sobre a altura da planta, índice de área foliar e rendimento de algodão em rama, mas não houve efeito sobre os dados de precocidade. A tensão de 200 kPa mostrou-se como o melhor nível de água no solo para se efetuar as irrigações, uma vez que para as tensões superiores o rendimento foi significativamente reduzido.O efeito sobre o rendimento foi de natureza quadrática (R² = 0,893**, o que indica que o rendimento máximo seria atingido irrigando-se a cultura com 52% de esgotamento da água disponível no solo.

  10. Jabuticaba-Induced Endothelium-Independent Vasodilating Effect on Isolated Arteries

    Directory of Open Access Journals (Sweden)

    Daniela Medeiros Lobo de Andrade

    2016-01-01

    Full Text Available Abstract Background: Despite the important biological effects of jabuticaba, its actions on the cardiovascular system have not been clarified. Objectives: To determine the effects of jabuticaba hydroalcoholic extract (JHE on vascular smooth muscle (VSM of isolated arteries. Methods: Endothelium-denuded aortic rings of rats were mounted in isolated organ bath to record isometric tension. The relaxant effect of JHE and the influence of K+ channels and Ca2+ intra- and extracellular sources on JHE-stimulated response were assessed. Results: Arteries pre-contracted with phenylephrine showed concentration-dependent relaxation (0.380 to 1.92 mg/mL. Treatment with K+ channel blockers (tetraethyl-ammonium, glibenclamide, 4-aminopyridine hindered relaxation due to JHE. In addition, phenylephrine-stimulated contraction was hindered by previous treatment with JHE. Inhibition of sarcoplasmic reticulum Ca2+ ATPase did not change relaxation due to JHE. In addition, JHE inhibited the contraction caused by Ca2+ influx stimulated by phenylephrine and KCl (75 mM. Conclusion: JHE induces endothelium-independent vasodilation. Activation of K+ channels and inhibition of Ca2+ influx through the membrane are involved in the JHE relaxant effect.

  11. Surface tension and dynamics of fingering patterns

    OpenAIRE

    Magdaleno Escar, Francesc Xavier; Casademunt i Viader, Jaume

    1998-01-01

    We study the minimal class of exact solutions of the Saffman-Taylor problem with zero surface tension, which contains the physical fixed points of the regularized (non-zero surface tension) problem. New fixed points are found and the basin of attraction of the Saffman-Taylor finger is determined within that class. Specific features of the physics of finger competition are identified and quantitatively defined, which are absent in the zero surface tension case. This has dramatic consequences f...

  12. The Surface Tension of Pure Liquid Compounds,

    Science.gov (United States)

    The surface tension tables presented herein are the result of a literature survey, evaluation, and compilation of data of some 2200 pure liquid... surface tension values to establish the regression curves and their equations. The constants of the equations (slope and intercept), together with the...standard deviations are given for each compound. The selection factors establishing criteria of quality of surface tension data are discussed. These

  13. Coupling of marine riser and tensioner system

    OpenAIRE

    Olssøn, Tor Trainer

    2011-01-01

    A coupled model of a marine riser and a tensioner system is built. The riser is modeled using the multi-body dynamics program MSC Adams, and the tensioner system using the powerful controls and systems simulation tool, MSC Easy5. The hydrodynamic forces on the marine riser are calculated according to linear wave theory, and implemented in the model using a custom made subroutine. The riser is modeled using flexible beam elements according to Timoshenko beam theory. The tensioner system is...

  14. Off-Equilibrium Surface Tension in Colloidal Suspensions

    Science.gov (United States)

    Truzzolillo, Domenico; Mora, Serge; Dupas, Christelle; Cipelletti, Luca

    2014-03-01

    We study the fingering instability of the interface between two miscible fluids, a colloidal suspension and its own solvent. The temporal evolution of the interface in a Hele-Shaw cell is found to be governed by the competition between the nonlinear viscosity of the suspension and an off-equilibrium, effective surface tension Γe. By studying suspensions in a wide range of volume fractions, ΦC, we show that Γe˜ΦC2, in agreement with Korteweg's theory for miscible fluids. The surface tension exhibits an anomalous increase with particle size, which we account for using entropy arguments.

  15. Effect of epithelium ATP release on cyclic pressure-induced airway mucus secretion.

    Science.gov (United States)

    Tong, Jin; Zhou, Xiang-Dong; Perelman, Juliy M; Kolosov, Victor P

    2014-02-01

    The cyclic mechanical effect of airflow during breathing creates the optimal airway hydration state. MUC (mucin) 5AC is an important component of the airway mucus. The formation of MUC5AC is related to ATP and intracellular calcium in the epithelial cells. In this study, we evaluated the effect of ATP release from intracellular calcium in epithelial cells on cyclic pressure-induced mucus secretion in the airway. 16HBE (human bronchial epithelial cells) were cultured in vitro on cyclically tilted cultured plates and divided into five groups: control, tilt, tilt and BAPTA-AM (1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid-acetoxymethyl ester), tilt and EGTA and tilt and RB-2 (reactive blue-2). The shear stress and compressive stress were induced by the surface tension of the liquid, atmospheric pressure and liquid gravity. Cell activity, MUC5AC mRNA expression level, MUC5AC protein expression level and ATP release and intracellular calcium changes were measured with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay, RT-PCR (reverse transcription-PCR), HPLC and inverted fluorescence microscope, respectively. We detected that cyclic pressure significantly increased MUC5AC secretion and ATP release. The enhanced ATP release could be inhibited by both BAPTA-AM and RB-2, while EGTA did not have a suppressive effect. BAPTA-AM, EGTA and RB-2 did not obviously inhibit MUC5AC mRNA expression. Cyclic pressure did not induce MUC5AC secretion in the airway mucus epithelium via Ca(2+)-dependent ATP release, and nearly all Ca(2+) was provided by stored intracellular Ca(2). © 2014 The author(s).

  16. Effect of epithelium ATP release on cyclic pressure-induced airway mucus secretion

    Science.gov (United States)

    Tong, Jin; Zhou, Xiang-dong; Perelman, Juliy M.; Kolosov, Victor P.

    2013-01-01

    The cyclic mechanical effect of airflow during breathing creates the optimal airway hydration state. MUC (mucin) 5AC is an important component of the airway mucus. The formation of MUC5AC is related to ATP and intracellular calcium in the epithelial cells. In this study, we evaluated the effect of ATP release from intracellular calcium in epithelial cells on cyclic pressure-induced mucus secretion in the airway. 16HBE (human bronchial epithelial cells) were cultured in vitro on cyclically tilted cultured plates and divided into five groups: control, tilt, tilt and BAPTA–AM (1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid–acetoxymethyl ester), tilt and EGTA and tilt and RB-2 (reactive blue-2). The shear stress and compressive stress were induced by the surface tension of the liquid, atmospheric pressure and liquid gravity. Cell activity, MUC5AC mRNA expression level, MUC5AC protein expression level and ATP release and intracellular calcium changes were measured with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay, RT–PCR (reverse transcription–PCR), HPLC and inverted fluorescence microscope, respectively. We detected that cyclic pressure significantly increased MUC5AC secretion and ATP release. The enhanced ATP release could be inhibited by both BAPTA–AM and RB-2, while EGTA did not have a suppressive effect. BAPTA–AM, EGTA and RB-2 did not obviously inhibit MUC5AC mRNA expression. Cyclic pressure did not induce MUC5AC secretion in the airway mucus epithelium via Ca2+-dependent ATP release, and nearly all Ca2+ was provided by stored intracellular Ca2+. PMID:27919041

  17. Neuroprotective effect of paeonol against isoflurane- induced ...

    African Journals Online (AJOL)

    expressions of apoptotic pathway proteins and mitogen activated protein kinases (MAPKs) were assessed by ... plants such as Paeonia albiflora and Paeonia moutan. ..... inhibitor of JNK, on transient brain ischemia/reperfusion- induced ...

  18. The effect of temperature on eccentric contraction-induced isometric force loss in isolated perfused rat medial gastrocnemius muscle

    Directory of Open Access Journals (Sweden)

    Vasaghi Gharamaleki B

    2008-09-01

    Full Text Available "nBackground: The typical features of eccentric exercise-induced muscle damage are delayed-onset muscle soreness (DOMS and prolonged loss of muscle strength. It has been shown that passive warmth is effective in reducing muscle injury. Due to the interaction of different systems in vivo, we used isolated perfused medial gastrocnemius skeletal muscle to study the direct effect of temperature on the eccentric contraction-induced force loss. "nMethods: After femoral artery cannulation of a rat, the left medial gastrocnemius muscle was separated and then the entire lower limb was transferred into a prewarmed (35oC chamber. With the chamber temperature at 31, 35 and 39oC before and during eccentric contraction. Isometric force loss was measured after 15 eccentric contractions (N=7-9. "nResults: Maximum contraction force reduction has been used as an index for eccentric contraction-induced force loss. In this study eccentric contraction caused a significant reduction in maximum isometric tension (p<0.01, but no significant difference was seen in isometric force loss at 31oC and 39oC compared with that at 35oC. "nConclusions: Our results suggest that temperature changes before or during eccentric contractions have no effect on eccentric contraction-induced force loss. "nKeywords: Isolated perfused muscle, skeletal muscle, eccentric contractions, isometric force, gastrocnemius muscle, temperature.

  19. Mechanisms of Hexachlorobenzene-induced Adverse Immune Effects

    NARCIS (Netherlands)

    Ezendam, Janine

    2004-01-01

    Hexachlorobenzene (HCB) is an environmental pollutant that can induce adverse immune effects in humans and rats. Brown Norway rats (BN) appeared to be very susceptible to HCB-induced immune effects. Oral exposure causes inflammatory skin and lung lesions, enlarged spleen and lymph nodes (LN) and

  20. Contrast-induced nephrotoxicity: possible synergistic effect of stress hyperglycemia.

    LENUS (Irish Health Repository)

    O'Donnell, David H

    2010-07-01

    Oxidative stress on the renal tubules has been implicated as a mechanism of injury in both stress hyperglycemia and contrast-induced nephrotoxicity. The purpose of this study was to determine whether the combination of these effects has a synergistic effect on accentuating renal tubular apoptosis and therefore increasing the risk of contrast-induced nephrotoxicity.

  1. Tension cost correlates with mechanical and biochemical parameters in different myocardial contractility conditions

    Directory of Open Access Journals (Sweden)

    Cleci M. Moreira

    2012-01-01

    Full Text Available OBJECTIVES: Tension cost, the ratio of myosin ATPase activity to tension, reflects the economy of tension development in the myocardium. To evaluate the mechanical advantage represented by the tension cost, we studied papillary muscle contractility and the activity of myosin ATPase in the left ventricles in normal and pathophysiological conditions. METHODS: Experimental protocols were performed using rat left ventricles from: (1 streptozotocin-induced diabetic and control Wistar rats; (2 N-nitro-L-arginine methyl ester (L-NAME hypertensive and untreated Wistar rats; (3 deoxycorticosterone acetate (DOCA salt-treated, nephrectomized and salt- and DOCA-treated rats; (4 spontaneous hypertensive rats (SHR and Wistar Kyoto (WKY rats; (5 rats with myocardial infarction and shamoperated rats. The isometric force, tetanic tension, and the activity of myosin ATPase were measured. RESULTS: The results obtained from infarcted, diabetic, and deoxycorticosterone acetate-salt-treated rats showed reductions in twitch and tetanic tension compared to the control and sham-operated groups. Twitch and tetanic tension increased in the N-nitro-L-arginine methyl ester-treated rats compared with the Wistar rats. Myosin ATPase activity was depressed in the infarcted, diabetic, and deoxycorticosterone acetate salt-treated rats compared with control and sham-operated rats and was increased in N-nitro-L-arginine methyl ester-treated rats. These parameters did not differ between SHR and WKY rats. In the studied conditions (e.g., post-myocardial infarction, deoxycorticosterone acetate salt-induced hypertension, chronic N-nitro-L-arginine methyl ester treatment, and streptozotocin-induced diabetes, a positive correlation between force or plateau tetanic tension and myosin ATPase activity was observed. CONCLUSION: Our results suggest that the myocardium adapts to force generation by increasing or reducing the tension cost to maintain myocardial contractility with a better

  2. Beneficial effect of Curcumin in Letrozole induced polycystic ovary syndrome

    Directory of Open Access Journals (Sweden)

    P. Sushma Reddy

    2016-04-01

    Conclusion: Curcumin showed beneficial effects in Letrozole induced PCOS in female Wistar rats. Its effect was comparable to that of Clomiphene citrate, most widely used treatment for ovulation induction in PCOS condition.

  3. ANTIOXIDANTS AMELIORATION OF ARSENICAL-INDUCED EFFECTS IN VIVO

    Science.gov (United States)

    Antioxidant amelioration of arsenical-induced effects in vivo. ES Hunter and EH Rogers. Reproductive Toxicology Division, NHEERL, US EPA, RTP, NC. Antioxidants have been reported to ameliorate the effects of many developmental toxicants. We tested the hypothesis that oxi...

  4. Surface tension in human pathophysiology and its application as a medical diagnostic tool.

    Science.gov (United States)

    Fathi-Azarbayjani, Anahita; Jouyban, Abolghasem

    2015-01-01

    Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states. In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed. Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted. It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice.

  5. Analysis of off-axis tension test of wood specimens

    Science.gov (United States)

    Jen Y. Liu

    2002-01-01

    This paper presents a stress analysis of the off-axis tension test of clear wood specimens based on orthotropic elasticity theory. The effects of Poisson's ratio and shear coupling coefficient on stress distribution are analyzed in detail. The analysis also provides a theoretical foundation for the selection of a 10° grain angle in wood specimens for the...

  6. Actin filaments as tension sensors.

    Science.gov (United States)

    Galkin, Vitold E; Orlova, Albina; Egelman, Edward H

    2012-02-07

    The field of mechanobiology has witnessed an explosive growth over the past several years as interest has greatly increased in understanding how mechanical forces are transduced by cells and how cells migrate, adhere and generate traction. Actin, a highly abundant and anomalously conserved protein, plays a large role in forming the dynamic cytoskeleton that is so essential for cell form, motility and mechanosensitivity. While the actin filament (F-actin) has been viewed as dynamic in terms of polymerization and depolymerization, new results suggest that F-actin itself may function as a highly dynamic tension sensor. This property may help explain the unusual conservation of actin's sequence, as well as shed further light on actin's essential role in structures from sarcomeres to stress fibers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Stress-state effects on the stress-induced martensitic transformation of carburized 4320 steels

    Science.gov (United States)

    Karaman, I.; Balzer, M.; Sehitoglu, Huseyin; Maier, H. J.

    1998-02-01

    The effect of different stress states on the stress-induced martensitic transformation of retained austenite was investigated in carburized 4320 steels with an initial retained austenite content of 15 pct. Experiments were conducted utilizing a specialized pressure rig and comparison between stress-strain behaviors of specimens with different austenitization and tempering histories was performed under these stress states. Experimental results indicated considerable asymmetry between tension and compression, with triaxial stress states resulting in the highest strength levels for the untempered material. Fine carbide precipitates due to low-temperature tempering increased the strength and ductility of the specimens and also changed the austenite-to-martensite transformation behavior. Numerical simulations of stress-strain behaviors under different stress states were obtained, with an existing micromechanical self-consistent framework utilizing the crystallographic theory of austenite/martensite transformation and the minimum complementary free-energy principle. The model was modified for carburized steels upon microstructural investigation and predicted the same trends in effective stress-effective strain behavior as observed experimentally.

  8. The influence of gradients in surface tension on the mass transfer in gas liquid systems

    NARCIS (Netherlands)

    Klooster, Hubertus Willem van der

    1978-01-01

    In this investigation attention has been paid to the influence of surface tensions gradients on the performance of a packed column. From earlier investigations it is known that surface tensions have a considerable influence on the magnitude of the effective interfacial area. The work presented here

  9. The remains of anterior cruciate ligament graft tension after cyclic knee motion

    NARCIS (Netherlands)

    Arnold, MR; Lie, DTT; Verdonschot, N; de Graaf, R; Amis, AA; van Kampen, A

    Background: There is sometimes a return of excess knee laxity after anterior cruciate ligament reconstruction. One of the contributing factors might be a loss in graft tension. It is unknown whether the tension imposed on an anterior cruciate ligament graft degrades with time and, if so, the effect

  10. The remains of anterior cruciate ligament graft tension after cyclic knee motion.

    NARCIS (Netherlands)

    Arnold, M.P.; Lie, D.T.; Verdonschot, N.J.J.; Graaf, R. de; Amis, A.A.; Kampen, A. van

    2005-01-01

    BACKGROUND: There is sometimes a return of excess knee laxity after anterior cruciate ligament reconstruction. One of the contributing factors might be a loss in graft tension. It is unknown whether the tension imposed on an anterior cruciate ligament graft degrades with time and, if so, the effect

  11. Tension Pneumothorax following an Accidental Kerosene Poisoning ...

    African Journals Online (AJOL)

    Tension pneumothorax is a rare complication following an accidental kerosene poisoning. In such situation, a bed-side needle thoracocentesis is performed because of its potential of becoming fatal; hence its clinical importance. A case of 15 month old boy with tension pneumothorax following accidental kerosene ...

  12. A TOGgle for Tension at Kinetochores.

    Science.gov (United States)

    Cheerambathur, Dhanya K; Prevo, Bram; Desai, Arshad

    2016-06-02

    Differential stability of kinetochore-microtubule attachments at low versus high tension is critical for accurate chromosome segregation. Miller et al. find that a TOG domain microtubule-binding protein imparts intrinsic tension selectivity to kinetochore-microtubule attachments. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Intraoperative Development of Tension Pneumocephalus in a ...

    African Journals Online (AJOL)

    A review of studies discussing the role of N2O in tension pneumocephalus has also been included. The article heightens awareness among. CASE. REPORT. Intraoperative Development of Tension Pneumocephalus in a. Patient Undergoing Repair of a Cranial‑dural Defect Under. Nitrous Oxide Anesthesia. Mansher Singh ...

  14. Tension and robustness in multitasking cellular networks.

    Directory of Open Access Journals (Sweden)

    Jeffrey V Wong

    Full Text Available Cellular networks multitask by exhibiting distinct, context-dependent dynamics. However, network states (parameters that generate a particular dynamic are often sub-optimal for others, defining a source of "tension" between them. Though multitasking is pervasive, it is not clear where tension arises, what consequences it has, and how it is resolved. We developed a generic computational framework to examine the source and consequences of tension between pairs of dynamics exhibited by the well-studied RB-E2F switch regulating cell cycle entry. We found that tension arose from task-dependent shifts in parameters associated with network modules. Although parameter sets common to distinct dynamics did exist, tension reduced both their accessibility and resilience to perturbation, indicating a trade-off between "one-size-fits-all" solutions and robustness. With high tension, robustness can be preserved by dynamic shifting of modules, enabling the network to toggle between tasks, and by increasing network complexity, in this case by gene duplication. We propose that tension is a general constraint on the architecture and operation of multitasking biological networks. To this end, our work provides a framework to quantify the extent of tension between any network dynamics and how it affects network robustness. Such analysis would suggest new ways to interfere with network elements to elucidate the design principles of cellular networks.

  15. Surface tension measurements with a smartphone

    Science.gov (United States)

    Goy, Nicolas-Alexandre; Denis, Zakari; Lavaud, Maxime; Grolleau, Adrian; Dufour, Nicolas; Deblais, Antoine; Delabre, Ulysse

    2017-11-01

    Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept of surface tension through simple experiments.

  16. Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage

    Directory of Open Access Journals (Sweden)

    McLeay Yanita

    2012-07-01

    Full Text Available Abstract Background Exercise-induced muscle damage (EIMD is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise. Methods In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA. Results A significant (p p = 0.047 interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p  Conclusions This study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise

  17. Initial tension loss in cerclage cables.

    Science.gov (United States)

    Ménard, Jérémie; Émard, Maxime; Canet, Fanny; Brailovski, Vladimir; Petit, Yvan; Laflamme, George Y

    2013-10-01

    Cerclage cables, frequently used in the management of fractures and osteotomies, are associated with a high failure rate and significant loosening during surgery. This study compared the capacity to maintain tension of different types of orthopaedic cable systems. Multifilament Cobalt-Chrome (CoCr) cables with four different crimp/clamp devices (DePuy, Stryker, Zimmer and Smith&Nephew) and one non-metallic Nylon (Ny) cable from Kinamed were instrumented with a load cell to measure tension during insertion. Significant tension loss was observed with crimping for all cables (Ptensioner led to an additional unexpected tension loss (CoCr-DePuy: 18%, CoCr-Stryker: 29%, CoCr-Smith&Nephew: 33%, Ny: 46%, and CoCr-Zimmer: 52%). The simple CoCr (DePuy) cable system outperformed the more sophisticated locking devices due to its significantly better ability to prevent tension loss. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Tension permeameter for deep borehole characterization

    Energy Technology Data Exchange (ETDEWEB)

    Sisson, J.B.; Honeycutt, T.K. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

    1994-12-31

    The permeability of geologic materials is an important variable for estimating the rate of transport of contaminants from waste sites. To date, permeability has been estimated in the laboratory from measurements made on small cores, under hydrologic conditions far removed from those of the field. Available field instruments cannot estimate permeabilities at depth under ambient conditions. The authors have constructed a borehole tension permeameter that is capable of operating at near field conditions and at depths of more than 30 m. The tension permeameter consists of a syringe pump, lightweight packer, semipermeable membrane, and pressure transducer, all controlled by a programmable logic controller. Water is metered at a fixed rate through the membrane while monitoring tension. The permeability is estimated from the steady pumping rate for the membrane geometry used at the measured water tension. The permeameter was used to estimate the permeability of Pancheri sandy loam at tensions of 0 to 150 cm.

  19. Aerial inventory of surficial geological effects induced by the recent Emilia earthquake (Italy: preliminary report

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    2012-10-01

    Full Text Available As a consequence of the two main shocks that recently struck the central alluvial Po Plain (May 20, 2012, Ml 5.9, and May 29, 2012, Ml 5.8, a great number of surficial geologic disturbances appeared over a wide area (ca. 500 km2, which extended up to 20 km from the epicenters. The affected area includes Mirabello, San Carlo, Sant'Agostino (Province of Ferrara, San Felice, Cavezzo, Concordia (Modena, Moglia and Quistello (Mantova. Most of the surficial effects that were observed during this study were clearly induced (directly or indirectly by sand liquefaction phenomena, such as sand volcanoes, burst of water and sand from domestic wells, tension cracks, lateral spreading and associated deformation, graben-like fracturing, and sink-holes. Other effects can probably be ascribed simply to the shaking of the ground (e.g., small collapses of irrigation canal walls. Lastly, there were also some features of dubious origin, such as two 'yellow crop spots' that are cited here with reservations. All of these data were surveyed by means of a small airplane that was especially adapted for this purpose. The aim of this study was to furnish a wide-ranging image of the surface deformation over the whole area impacted by these recent earthquakes, as an instrument towards more exhaustive research, both at the scientific and technical levels (e.g., seismic microzonation. […

  20. Evaluation of the Effect of the Volume Throughput and Maximum Flux of Low-Surface-Tension Fluids on Bacterial Penetration of 0.2 Micron-Rated Filters during Process-Specific Filter Validation Testing.

    Science.gov (United States)

    Folmsbee, Martha

    2015-01-01

    Approximately 97% of filter validation tests result in the demonstration of absolute retention of the test bacteria, and thus sterile filter validation failure is rare. However, while Brevundimonas diminuta (B. diminuta) penetration of sterilizing-grade filters is rarely detected, the observation that some fluids (such as vaccines and liposomal fluids) may lead to an increased incidence of bacterial penetration of sterilizing-grade filters by B. diminuta has been reported. The goal of the following analysis was to identify important drivers of filter validation failure in these rare cases. The identification of these drivers will hopefully serve the purpose of assisting in the design of commercial sterile filtration processes with a low risk of filter validation failure for vaccine, liposomal, and related fluids. Filter validation data for low-surface-tension fluids was collected and evaluated with regard to the effect of bacterial load (CFU/cm(2)), bacterial load rate (CFU/min/cm(2)), volume throughput (mL/cm(2)), and maximum filter flux (mL/min/cm(2)) on bacterial penetration. The data set (∼1162 individual filtrations) included all instances of process-specific filter validation failures performed at Pall Corporation, including those using other filter media, but did not include all successful retentive filter validation bacterial challenges. It was neither practical nor necessary to include all filter validation successes worldwide (Pall Corporation) to achieve the goals of this analysis. The percentage of failed filtration events for the selected total master data set was 27% (310/1162). Because it is heavily weighted with penetration events, this percentage is considerably higher than the actual rate of failed filter validations, but, as such, facilitated a close examination of the conditions that lead to filter validation failure. In agreement with our previous reports, two of the significant drivers of bacterial penetration identified were the total

  1. Effect of a heme oxygenase-1 inducer on NADPH oxidase ...

    African Journals Online (AJOL)

    Purpose: To investigated the effect of hemin, a heme oxygenase-1 (HO-1) inducer, on nicotinamide adenine dinucleotide phosphate oxidase (NOX) expression in rats with alcohol-induced liver injury. Methods: Male Wistar rats were randomly divided into four groups consisting of the control group, the ethanol (EtOH) group, ...

  2. Grouping effects in flash-induced perceptual fading

    NARCIS (Netherlands)

    Vergeer, M.L.T.; Lier, R.J. van

    2007-01-01

    We show that the flash-induced fading effect can be influenced by grouping based on colour and shape similarity. In flash-induced fading, peripherally presented elements perceptually disappear after a flash has been presented around or next to the element(s) (Kanai and Kamitani, 2003 Journal of

  3. Chemopreventive effect of Annona muricata on DMBA-induced cell ...

    African Journals Online (AJOL)

    DNA smears obtained from agarose gel electrophoresis suggested possible DMBA-induced damage which was significantly prevented owing to the effect of the leaf extract of A. muricataleaves. Histological assay revealed the presence of DMBA induced lobular alveolar hyperplasia, adenomatoid hyperplasia, fibro adipose ...

  4. Effect of melatonin on carbon tetrachloride- induced kidney injury in ...

    African Journals Online (AJOL)

    Exposure to carbon tetrachloride (CCl4) induces acute and chronic renal injuries as well as oxidative stress in rats. The aim of this study was to evaluate the effect of exogenous melatonin (MEL) treatment on CCl4-induced oxidative stress and nephrotoxicity in rats using histopathological and biochemical parameters. Serum ...

  5. Induced response in Schima superba : Effects of earlyseason ...

    African Journals Online (AJOL)

    Induced response in Schima superba : Effects of earlyseason herbivory on leaf traits and subsequent insect attack. ... This study gave an additional evidence to the induced defense theory through the simulated herbivory in Schima superba, one of the common dominant trees in subtropical evergreen broadleaf forests, ...

  6. Protective effect of nitric oxide against arsenic-induced oxidative ...

    African Journals Online (AJOL)

    Nitric oxide (NO) is a key molecule involved in many physiology processes. The effects of NO on alleviating arsenic-induced oxidative damage in tall fescue leaves were investigated. Arsenic (25 M) treatment induced significantly accumulation of reactive oxygen species (ROS) and led to serious lipid peroxidation in tall ...

  7. Surface Tension Driven Convection Experiment (STDCE)

    Science.gov (United States)

    Ostrach, S.; Kamotani, Y.

    1996-01-01

    This document reports the results obtained from the Surface Tension Driven Convection Experiment (STDCE) conducted aboard the USML-1 Spacelab in 1992. The experiments used 10 cSt silicone oil placed in an open circular container that was 10 cm wide and 5 cm deep. Thermocapillary flow was induced by using either a cylindrical heater placed along the container centerline or by a CO2 laser. The tests were conducted under various power settings, laser beam diameters, and free surface shapes. Thermistors located at various positions in the test section recorded the temperature of the fluid, heater, walls, and air. An infrared imager was used to measure the free surface temperature. The flow field was studied by flow visualization and the data was analyzed by a PTV technique. The results from the flow visualization and the temperature measurements are compared with the numerical analysis that was conducted in conjunction with the experiment. The compared results include the experimental and numerical velocity vector plots, the streamline plots, the fluid temperature, and the surface temperature distribution.

  8. A novel optimal sensitivity design scheme for yarn tension sensor using surface acoustic wave device.

    Science.gov (United States)

    Lei, Bingbing; Lu, Wenke; Zhu, Changchun; Liu, Qinghong; Zhang, Haoxin

    2014-08-01

    In this paper, we propose a novel optimal sensitivity design scheme for the yarn tension sensor using surface acoustic wave (SAW) device. In order to obtain the best sensitivity, the regression model between the size of the SAW yarn tension sensor substrate and the sensitivity of the SAW yarn tension sensor was established using the least square method. The model was validated too. Through analyzing the correspondence between the regression function monotonicity and its partial derivative sign, the effect of the SAW yarn tension sensor substrate size on the sensitivity of the SAW yarn tension sensor was investigated. Based on the regression model, a linear programming model was established to gain the optimal sensitivity of the SAW yarn tension sensor. The linear programming result shows that the maximum sensitivity will be achieved when the SAW yarn tension sensor substrate length is equal to 15 mm and its width is equal to 3mm within a fixed interval of the substrate size. An experiment of SAW yarn tension sensor about 15 mm long and 3mm wide was presented. Experimental results show that the maximum sensitivity 1982.39 Hz/g was accomplished, which confirms that the optimal sensitivity design scheme is useful and effective. Copyright © 2014. Published by Elsevier B.V.

  9. Relaxant effect of U0126 in hemolysate-, oxyhemoglobin-, and bloody cerebrospinal fluid-induced contraction in rabbit basilar artery.

    Science.gov (United States)

    Zubkov, A Y; Rollins, K S; McGehee, B; Parent, A D; Zhang, J H

    2001-01-01

    It has been suggested that mitogen-activated protein kinase (MAPK) is involved in cerebral vasospasm after subarachnoid hemorrhage. The present study was undertaken to explore the inhibitory effect of U0126, a novel MAPK inhibitor, in the contraction of the rabbit basilar artery by 3 spasmogens: hemolysate, oxyhemoglobin, and bloody cerebrospinal fluid (CSF) from patients with vasospasm. The contraction and relaxation of rabbit basilar arteries were measured by isometric tension. MAPK immunoprecipitation was assessed by Western blot analysis. (1) Pretreatment of the rabbit basilar arteries with U0126 reduced contractions to hemolysate, oxyhemoglobin, or bloody CSF applied subsequently. (2) In the absence of endothelial cells, U0126 produced an inhibitory effect similar to the contractions induced by hemolysate, oxyhemoglobin, or bloody CSF. (3) U0126 relaxed the sustained contraction induced by hemolysate, oxyhemoglobin, or bloody CSF. (4) Hemolysate, oxyhemoglobin, and bloody CSF enhanced MAPK immunoprecipitation. (5) U0126 reduced MAPK immunoprecipitation induced by hemolysate, oxyhemoglobin, and bloody CSF. (6) Hemolysate, oxyhemoglobin, and bloody CSF significantly increased MAPK activity in the rabbit basilar artery. (7) U0126 abolished the effect of hemolysate, oxyhemoglobin, or bloody CSF on MAPK activation. This study demonstrated a role of MAPK in the contraction of rabbit basilar arteries by hemolysate, oxyhemoglobin, and bloody CSF. MAPK inhibitor U0126 may be useful in the treatment of cerebral vasospasm.

  10. Do 'sliders' slide and 'tensioners' tension? An analysis of neurodynamic techniques and considerations regarding their application.

    Science.gov (United States)

    Coppieters, Michel W; Butler, David S

    2008-06-01

    Despite the high prevalence of carpal tunnel syndrome and cubital tunnel syndrome, the quality of clinical practice guidelines is poor and non-invasive treatment modalities are often poorly documented. The aim of this cadaveric biomechanical study was to measure longitudinal excursion and strain in the median and ulnar nerve at the wrist and proximal to the elbow during different types of nerve gliding exercises. The results confirmed the clinical assumption that 'sliding techniques' result in a substantially larger excursion of the nerve than 'tensioning techniques' (e.g., median nerve at the wrist: 12.6 versus 6.1mm, ulnar nerve at the elbow: 8.3 versus 3.8mm), and that this larger excursion is associated with a much smaller change in strain (e.g., median nerve at the wrist: 0.8% (sliding) versus 6.8% (tensioning)). The findings demonstrate that different types of nerve gliding exercises have largely different mechanical effects on the peripheral nervous system. Hence different types of techniques should not be regarded as part of a homogenous group of exercises as they may influence neuropathological processes differently. The findings of this study and a discussion of possible beneficial effects of nerve gliding exercises on neuropathological processes may assist the clinician in selecting more appropriate nerve gliding exercises in the conservative and post-operative management of common neuropathies.

  11. Dynamical Modeling of Surface Tension

    Science.gov (United States)

    Brackbill, Jeremiah U.; Kothe, Douglas B.

    1996-01-01

    In a recent review it is said that free-surface flows 'represent some of the difficult remaining challenges in computational fluid dynamics'. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF formulation might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin (1996). This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated. For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin (1996), are discussed.

  12. Effects of Induced Stress on Seismic Forward Modelling and Inversion

    Science.gov (United States)

    Tromp, Jeroen; Trampert, Jeannot

    2018-01-01

    We demonstrate how effects of induced stress may be incorporated in seismic modelling and inversion. Our approach is motivated by the accommodation of prestress in global seismology. Induced stress modifies both the equation of motion and the constitutive relationship. The theory predicts that induced pressure linearly affects the unstressed isotropic moduli with a slope determined by their adiabatic pressure derivatives. The induced deviatoric stress produces anisotropic compressional and shear wavespeeds; the latter result in shear-wave splitting. For forward modelling purposes, we determine the weak form of the equation of motion under induced stress. In the context of the inverse problem, we determine induced stress sensitivity kernels, which may be used for adjoint tomography. The theory is illustrated by considering 2D propagation of SH waves and related Fréchet derivatives based on a spectral-element method.

  13. Cardioprotective Effects Induced by Preconditioning with Halogenated Anesthetics

    Directory of Open Access Journals (Sweden)

    Papurica Marius

    2016-06-01

    Full Text Available Background: Numerous studies discuss the protective effects of halogenated anesthetics on myocyte injury induced by the ischemia-reperfusion syndrome of the heart. This mechanism is known as pharmacological preconditioning.

  14. Effect of Stress Management Training Based on PRECEDE Model on Prehospital Emergency Staff Occupational Tension in Mazandaran University of Medical Sciences in 2016

    Directory of Open Access Journals (Sweden)

    Gholamreza Esmailzadeh Gatabi

    2017-10-01

    Conclusion: The findings showed that education based on PRECEDE model increases the predisposing factor (knowledge and attitude, reinforcing factor, and enhancer factor. These factors have the potential to affect the behavior more effectively. According to this, educational intervention based on PRECEDE model structures is effective on job stress and behavior. Researchers have suggested training on this pattern.

  15. Tension and Robustness in Multitasking Cellular Networks

    Science.gov (United States)

    Wong, Jeffrey V.; Li, Bochong; You, Lingchong

    2012-01-01

    Cellular networks multitask by exhibiting distinct, context-dependent dynamics. However, network states (parameters) that generate a particular dynamic are often sub-optimal for others, defining a source of “tension” between them. Though multitasking is pervasive, it is not clear where tension arises, what consequences it has, and how it is resolved. We developed a generic computational framework to examine the source and consequences of tension between pairs of dynamics exhibited by the well-studied RB-E2F switch regulating cell cycle entry. We found that tension arose from task-dependent shifts in parameters associated with network modules. Although parameter sets common to distinct dynamics did exist, tension reduced both their accessibility and resilience to perturbation, indicating a trade-off between “one-size-fits-all” solutions and robustness. With high tension, robustness can be preserved by dynamic shifting of modules, enabling the network to toggle between tasks, and by increasing network complexity, in this case by gene duplication. We propose that tension is a general constraint on the architecture and operation of multitasking biological networks. To this end, our work provides a framework to quantify the extent of tension between any network dynamics and how it affects network robustness. Such analysis would suggest new ways to interfere with network elements to elucidate the design principles of cellular networks. PMID:22577355

  16. Surface tension of water in the presence of perfluorocarbon vapors.

    Science.gov (United States)

    Chernyshev, Vasiliy S; Skliar, Mikhail

    2014-03-28

    Fluorocarbons are highly hydrophobic, biocompatible compounds with a variety of medical applications. Despite significant interest, the study of interfacial properties of fluorocarbons in aqueous systems has received limited attention. In this study, we investigate the influence of perfluoropentane and perfluorohexane vapors on the surface tension of water at room temperature. The results show a substantial decrease in the surface tension of water in the presence of perfluorocarbon vapors. In the investigated range of partial pressures up to the saturation value, a linear correlation between the surface tension and the partial pressure was found. This suggests that an adsorbed perfluorocarbon layer is formed on the surface of water. For comparison, the effect of the perfluorocarbon vapor on the surface tension of methanol was also investigated and a similar dependence was observed. Our results indicate that the stability and dynamic transitions of fluorocarbon colloids, which may be dispersed under physiological conditions as microdroplets, bubbles, or their combination, are likely affected by the composition of liquid and gas phases.

  17. Masseter muscle tension and chewing ability in older persons.

    Science.gov (United States)

    Ohara, Yuki; Hirano, Hirohiko; Watanabe, Yutaka; Edahiro, Ayako; Sato, Emiko; Shinkai, Shoji; Yoshida, Hiroto; Mataki, Shiro

    2013-04-01

    Mastication is an important function to maintain, not only for oral health, but also for quality of life. An easy-to-use method to evaluate the chewing ability of elderly people in any environment is necessary. Few studies have discussed the effectiveness of the masseter muscle by palpation. The purpose of this study was to clarify the availability of masseter muscle tension assessment methods by investigating its relationship with oral health status, and comparing it with other methods of assessing chewing ability. This cross-sectional study was carried out with 547 community-dwelling elderly subjects (246 men and 301 women; mean age 73.8 ± 6.2 years) who participated in a comprehensive annual geriatric health examination in 2010 at Kusatsu, Gunma, Japan. Chewing ability was evaluated by masseter muscle tension palpation, differences of masseter muscle thickness, occlusal force, self-reported chewing ability, and the number of remaining and functional teeth. Masseter muscle thickness was measured by ultrasonography. Masseter muscle thickness and occlusal force showed significant differences between males and females. The strength of masseter muscle tension palpation was significantly associated with men's occlusal force, masseter muscle thickness, the number of remaining and functional teeth, and self-reported chewing ability (P muscle thickness, the number of remaining teeth, and self-reported chewing ability and results of palpation (P palpation of masseter muscle tension is a reliable and easy-to-use method to evaluate the chewing ability of elderly people. © 2012 Japan Geriatrics Society.

  18. Protective Effect of Antioxidants against Rifampicin Induced ...

    African Journals Online (AJOL)

    Rifampicin is an effective first line drug in the management of tuberculosis. It has been documented to have some toxic effects in humans. Thus, this study intends to investigate the modulatory effects of Vitamins C and E on the haematopoietic suppression caused by Rifampicin. A total of 40 Wister albino rats of 10 animals ...

  19. Viscous Fingering on an Immiscible Reactive Interface with Variation of Interfacial Tension

    Science.gov (United States)

    Tsuzuki, Reiko; Nagatsu, Yuichiro; Li, Qian; Chen, Ching-Yao

    2017-11-01

    The effects of chemical reaction, in which surfactants are produced on the interface of two immiscible fluids, on viscous fingering in a radial Hele-Shaw flow are numerically investigated. The presence of surfactants reduces interfacial tension, which is an important factor to the fingering pattern formation. In the present study, influences of reaction rate and dispersion of produced surfactants, represented respectively by dimensionless parameters of Damkohler number and Peclet number, are evaluated systematically. Secondary fingering instability, e.g., tip-splitting and side-branching, is triggered by chemical reactions. Weaker surface tension generally induces tip-splitting. For the case of high Damkohler number, because of the vortex pairs generated within each finger, surfactant tends to accumulate significantly on the side of finger, so that side-branching is preferred. Nevertheless, side-branching is suppressed in the cases associated with low Peclet number, in which strong dispersion reduces the local variation of surfactant concentration. Considering the coupled effects by Damkohler number and Peclet number, the patterns obtained by the simulations qualitatively agree with the observations in the experiments.

  20. Grander system: a new technology to reduce surface tension of adhesive systems in dentistry.

    Science.gov (United States)

    Gonçalves, Sérgio Eduardo de Paiva; Cruz, Nilson; Brayner, Ricardo; Huhtala, Maria Filomena Rocha Lima; Borges, Alessandra Bühler; Barcellos, Daphne Câmara

    2014-01-01

    Reduced surface tension of liquids results in higher surface wetting ability and diffusivity by the substrate. The objective of this study was to evaluate the influence of the Grander Technology in reducing the surface tension of adhesive systems. Two adhesive systems (self-etch and total-etch) were modified by physical contact with the Grander system Flexible unit to revitalize water, for 48 h. Surface tension of adhesive systems and water in normal and grander-modified conditions was measured with a goniometer. The results showed a reduction of surface tension for all conditions grander-modified between 3-15%. Grander Technology was effective in reducing the surface tension of the Single Bond and Clearfil SE Bond adhesive systems. Clinical significance. Grander technology was employed to restructure the molecular structure of water-based adhesive systems, which can increase their wetness capacity and therefore ensure a greater diffusibility.

  1. Field Evaluation of the System Identification Approach for Tension Estimation of External Tendons

    Directory of Open Access Journals (Sweden)

    Myung-Hyun Noh

    2015-01-01

    Full Text Available Various types of external tendons are considered to verify the applicability of tension estimation method based on the finite element model with system identification technique. The proposed method is applied to estimate the tension of benchmark numerical example, model structure, and field structure. The numerical and experimental results show that the existing methods such as taut string theory and linear regression method show large error in the estimated tension when the condition of external tendon is different with the basic assumption used during the derivation of relationship between tension and natural frequency. However, the proposed method gives reasonable results for all of the considered external tendons in this study. Furthermore, the proposed method can evaluate the accuracy of estimated tension indirectly by comparing the measured and calculated natural frequencies. Therefore, the proposed method can be effectively used for field application of various types of external tendons.

  2. Dynamic surface tension measurements of ionic surfactants using maximum bubble pressure tensiometry

    Science.gov (United States)

    Ortiz, Camilla U.; Moreno, Norman; Sharma, Vivek

    Dynamic surface tension refers to the time dependent variation in surface tension, and is intimately linked with the rate of mass transfer of a surfactant from liquid sub-phase to the interface. The diffusion- or adsorption-limited kinetics of mass transfer to interfaces is said to impact the so-called foamability and the Gibbs-Marangoni elasticity of surfaces. Dynamic surface tension measurements carried out with conventional methods like pendant drop analysis, Wilhelmy plate, etc. are limited in their temporal resolution (>50 ms). In this study, we describe design and application of maximum bubble pressure tensiometry for the measurement of dynamic surface tension effects at extremely short (1-50 ms) timescales. Using experiments and theory, we discuss the overall adsorption kinetics of charged surfactants, paying special attention to the influence of added salt on dynamic surface tension.

  3. Effect of oxidation and surface roughness on the shear strength of single-lap-joint adhesively bonded metal specimens by tension loading

    National Research Council Canada - National Science Library

    Khan, M H; Gali, O A; Edrisy, A; Riahi, A R

    2016-01-01

    An experimental investigation was performed to study the effect of surface roughness and oxidation on the shear strength of single-lap-joints of AA6061, AA7075 aluminum alloys and an AISI 1080 steel...

  4. Designing a tensioning mechanism for a belt-driven integrated starter-generator system

    Energy Technology Data Exchange (ETDEWEB)

    Olatunde, A.O.; Zu, J.W. [Toronto Univ., ON (Canada)

    2009-07-01

    A belt-driven integrated starter generator (B-ISG) system was presented. Equations of motion (EOM) were used to model the system's passive twin-arm tensioner. EOMs were derived by determining moment equilibrium equations for the system's rigid bodies, as well as equations for the relationship between belt span tensions and rigid body displacements. A parametric study was conducted to evaluate the effect of the twin tensioner's parameters on the static tension of each belt span. Genetic algorithms and sequential quadratic programming (SQP) searches were conducted to determine values for the design variables needed to reduce static tension in taut and slack spans. A conventional alternator pulley design was used to model system geometry, inertia, stiffness and damping. The study showed that the twin tensioner reduced the magnitudes of the static tension for the belt spans of the ISG system. The slackest and tautest belt spans decreased and increased together during operational phases. It was concluded that additional pre-tension is required in order to compensate for slack spans in the ISG-driving phase of operation. 3 figs.

  5. Gastrothorax or tension pneumothorax: A diagnostic dilemma

    Directory of Open Access Journals (Sweden)

    Singh Sarvesh

    2011-01-01

    Full Text Available Gastrothorax, a rare complication following thoracoabdominal aortic aneurysm repair, is reported. The clinical features of a gastrothorax and tension pneumothorax are similar and thus, a gastrothorax can masquerade as a tension pneumothorax. The diagnosis is made by a high level of clinical suspicion, chest X-ray shows a distended stomach with air fluid levels and a computerised tomography is useful in assessing the diaphragm and establishing the positions of the various intra-abdominal organs. Also, the risk of an intercostal drainage tube placement and the role of nasogastric tube in avoiding the development of a tension gastrothorax is highlighted.

  6. Surface tension profiles in vertical soap films

    Science.gov (United States)

    Adami, N.; Caps, H.

    2015-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

  7. Chemopreventive effect of tadalafil in cisplatin-induced ...

    African Journals Online (AJOL)

    Summary: Nephrotoxicity remains a common untoward effect of cisplatin therapy with limited effective chemopreventive options available till date. This study aims to evaluate the possible chemopreventive effect and mechanism(s) of action of 2 mgkg-1 and 5 mgkg-1 of Tadalafil in cisplatin-induced nephrotoxic rats. In this ...

  8. Treating tension-type headache -- an expert opinion

    DEFF Research Database (Denmark)

    Bendtsen, Lars; Jensen, Rigmor

    2011-01-01

    INTRODUCTION: Tension-type headache (TTH) is a highly prevalent disorder with enormous costs for the individual and the society. AREAS COVERED: Nonpharmacological and pharmacological treatments are reviewed. Electromyographic (EMG) biofeedback has a documented effect in TTH, while cognitive......-behavioral therapy and relaxation training are most likely to be effective. Physical therapy and acupuncture may be valuable options for patients with frequent TTH. Simple analgesics and nonsteroidal anti-inflammatory drugs are recommended for treatment of episodic TTH. Combination analgesics containing caffeine...

  9. Homeostatic Cell Growth Is Accomplished Mechanically through Membrane Tension Inhibition of Cell-Wall Synthesis.

    Science.gov (United States)

    Rojas, Enrique R; Huang, Kerwyn Casey; Theriot, Julie A

    2017-11-30

    Feedback mechanisms are required to coordinate balanced synthesis of subcellular components during cell growth. However, these coordination mechanisms are not apparent at steady state. Here, we elucidate the interdependence of cell growth, membrane tension, and cell-wall synthesis by observing their rapid re-coordination after osmotic shocks in Gram-positive bacteria. Single-cell experiments and mathematical modeling demonstrate that mechanical forces dually regulate cell growth: while turgor pressure produces mechanical stress within the cell wall that promotes its expansion through wall synthesis, membrane tension induces growth arrest by inhibiting wall synthesis. Tension inhibition occurs concurrently with membrane depolarization, and depolarization arrested growth independently of shock, indicating that electrical signals implement the negative feedback characteristic of homeostasis. Thus, competing influences of membrane tension and cell-wall mechanical stress on growth allow cells to rapidly correct for mismatches between membrane and wall synthesis rates, ensuring balanced growth. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Influence of specimen type and reinforcement on measured tension-tension fatigue life of unidirectional GFRP laminates

    DEFF Research Database (Denmark)

    Korkiakoski, Samuli; Brøndsted, Povl; Sarlin, Essi

    2016-01-01

    It is well known that standardised tension-tension fatigue test specimens of unidirectional (UD) glass-fibre-reinforced plastics (GFRP) laminates tend to fail at end tabs. The true fatigue life is then underestimated. The first objective of this study was to find for UD GFRP laminates a test spec...... a significant effect on the failure mode and measured fatigue life of the laminates. A significantly higher fatigue life was measured for the laminate with the powder-bound fabric reinforcement when compared to the laminate with the stitched reinforcement.......It is well known that standardised tension-tension fatigue test specimens of unidirectional (UD) glass-fibre-reinforced plastics (GFRP) laminates tend to fail at end tabs. The true fatigue life is then underestimated. The first objective of this study was to find for UD GFRP laminates a test...... specimen that fails in the gauge section. The second objective was to compare fatigue performance of two laminates, one having a newly developed UD powder-bound fabric as a reinforcement and the other having a quasi-UD stitched non-crimp fabric as a reinforcement. In the first phase, a rectangular specimen...

  11. Protective Effects of Cilastatin against Vancomycin-Induced Nephrotoxicity

    Directory of Open Access Journals (Sweden)

    Blanca Humanes

    2015-01-01

    Full Text Available Vancomycin is a very effective antibiotic for treatment of severe infections. However, its use in clinical practice is limited by nephrotoxicity. Cilastatin is a dehydropeptidase I inhibitor that acts on the brush border membrane of the proximal tubule to prevent accumulation of imipenem and toxicity. The aim of this study was to investigate the potential protective effect of cilastatin on vancomycin-induced apoptosis and toxicity in cultured renal proximal tubular epithelial cells (RPTECs. Porcine RPTECs were cultured in the presence of vancomycin with and without cilastatin. Vancomycin induced dose-dependent apoptosis in cultured RPTECs, with DNA fragmentation, cell detachment, and a significant decrease in mitochondrial activity. Cilastatin prevented apoptotic events and diminished the antiproliferative effect and severe morphological changes induced by vancomycin. Cilastatin also improved the long-term recovery and survival of RPTECs exposed to vancomycin and partially attenuated vancomycin uptake by RPTECs. On the other hand, cilastatin had no effects on vancomycin-induced necrosis or the bactericidal effect of the antibiotic. This study indicates that cilastatin protects against vancomycin-induced proximal tubule apoptosis and increases cell viability, without compromising the antimicrobial effect of vancomycin. The beneficial effect could be attributed, at least in part, to decreased accumulation of vancomycin in RPTECs.

  12. Rheological Parameters as Affected by Water Tension in Subtropical Soils

    Directory of Open Access Journals (Sweden)

    Patricia Pértile

    2016-01-01

    Full Text Available ABSTRACT Rheological parameters have been used to study the interaction between particles and the structural strength of soils subjected to mechanical stresses, in which soil composition and water content most strongly affect soil resistance to deformation. Our objective was to evaluate the effect of water tension on rheological parameters of soils with different mineralogical, physical, and chemical composition. Surface and subsurface horizons of four Oxisols, two Ultisols, one Alfisol, and one Vertisol were physically and chemically characterized; their rheological parameters were obtained from amplitude sweep tests under oscillatory shear on disturbed soil samples that were saturated and subjected to water tension of 1, 3, 6, and 10 kPa. In these samples, the rheological parameters linear viscoelastic deformation limit (γL, maximum shear stress (τmax, and integral z were determined. By simple regression analysis of the rheological parameters as a function of soil water tension, we observed increased mechanical strength with increasing water tension up to at least 6 kPa, primarily due to increased capillary forces in the soil. However, increased elasticity assessed by γL was not as expressive as the increase in structural rigidity assessed by τmax and integral z. Elastic deformation of the soil (γL increases with the increase in the number of bonds among particles, which depend on the clay, total carbon, expansive clay mineral, and cation contents; however, maximum shear resistance (τmax and structural stiffness (integral z mainly increase with clay, kaolinite, and oxide content by increasing the strength of interparticle bonds. A decrease in mechanical strength occurs for water tension of 10 kPa (the lowest water content evaluated in sandy horizons or in horizons with a high proportion of resistant microaggregates (pseudosand, when associated with low bulk density, due to fewer points of contact between soil particles and therefore

  13. Perception of tension in music: musicians versus nonmusicians.

    Science.gov (United States)

    Fredrickson, W E

    2000-01-01

    Music therapists are often highly trained musicians who deal with diverse populations, most of whom do not have formal musical training. Questions may arise regarding the issue of a therapist's ability to understand, and predict, the musical perceptions and preferences of a client when their own background is so different. The current work is a look at a series of studies using various musical stimuli and comparing responses of musicians and nonmusicians to perceived "musical tension." Subjects (N = 126) included adult musicians and nonmusicians as well as a case study of a father/daughter. All subjects listened to recordings through individual headphones and were physically isolated from other subjects to ensure individuality of responses. Subjects, whether adults or children, were given instructions telling them that they were about to hear a piece of music and that they would be using a Continuous Response Digital Interface (CRDI) dial to trace the musical tension they heard. No specific definition of musical tension was given to any of the subjects. In effect, individual subjects supplied their own definition, either knowingly or unknowingly, in the absence of a formal one. Results indicated that group perceptions of the points at which tension and its release were strongest are remarkably similar between musicians and nonmusicians (correlations ranged from r =.71 to r =.95). Within at least the western art music tradition the likelihood that perceptions of group responses to tension and release in music could be predicted is high. These data indicate that therapists, trained as musicians, might be able to predict with some accuracy the responses of their clients who are not trained musicians.

  14. Modelling Tension Stiffening in Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1997-01-01

    Part I of the present thesis deals with crack formation in reinforced concrete and the phenomenon of tension stiffening in concrete tension rods reinforced with deformed bars.Two physical models are presented for uniaxial tension, and they are modified for application on beams subjected to pure...... predicted by the models are compared with experimental data from tests on tension rods as well as flexural beams.In the light of the simple assumptions made and the random nature of cracking, the accordance between the models and the test data is quite good.Part II of the present thesis deals...... of the simple assumptions, quite good accordance is found.Part III of the thesis deals with the deformations of a beam symmetrically loaded by two concentrated forces. In the shear-flexure beam model it is assumed that the load is carried by means of a stringer system and a diagonal stress field in the shear...

  15. Transcutaneous oxygen tension in imminent foot gangrene

    DEFF Research Database (Denmark)

    Tønnesen, K H

    1978-01-01

    Transcutaneous oxygen tension at 44 degree C and maximal isotope clearance (90m Tc-pretechnetate + histramine) just proximal to the 1st toe and systolic toe blood pressure (strain gauge) were studied on a tilt table in patients with various degrees of obstructive arteriosclerotic disease. In legs...... with moderate obstruction, the oxygen tension reached zero at a toe systolic blood pressure of 5--10 mmHg (tilt toe up) and reached arterial oxygen tension at about 50 to 70 mmHg (tilt toe down). In legs withsevere arterial obstruction and ischaemic rest pain, oxygen tension rose from zero not before systolic...... toe blood pressure reached 20--50 mmHg. Significant isotope clearance was seen at pressures below the limits just mentioned for both types of patients. This phenomenon here seen of a perfusion without oxygen supply is explained by a gas leak (rendered significant because of the slow flow rate) from...

  16. Doppler effect induced spin relaxation boom

    National Research Council Canada - National Science Library

    Zhao, Xinyu; Huang, Peihao; Hu, Xuedong

    2016-01-01

    .... We find that Doppler effect leads to several interesting phenomena. In particular, spin relaxation rate peaks when the QD motion is in the transonic regime, which we term a spin relaxation boom in analogy to the classical sonic boom...

  17. Tension Hydrothorax Related to Disseminated Endometriosis

    Directory of Open Access Journals (Sweden)

    AnnaKate Deal, MD

    2016-01-01

    Full Text Available We present the case of a 34-year-old woman presenting to the emergency department (ED with dyspnea, cough, and fever. She was found to have a tension hydrothorax and was treated with ultrasound-guided thoracentesis in the ED. Subsequent inpatient evaluation showed the patient had disseminated endometriosis. Tension hydrothorax has not been previously described in the literature as a complication of this disease.

  18. Leadership matters: Tensions in evaluating leadership development

    OpenAIRE

    Jarvis, C.; Gulati, A.; McCririck, V.; Simpson, P.

    2013-01-01

    The Problem and Solution: This paper explores some of the tensions that required careful management in the design and delivery of a leadership development program. This discussion draws particularly upon a formal evaluation of two cohorts, each comprising approximately 20 senior managers working in adult social care. Complexity theory, notably Complex Responsive Processes of Relating, is used to make visible, explore and articulate the need to hold in tension apparently contradictory forces a...

  19. The accuracy of fine wire tensioners: a comparison of five tensioners used in hybrid and ring external fixation.

    Science.gov (United States)

    Roberts, Craig S; Antoci, Valentin; Antoci, Valentin; Voor, Michael J

    2004-03-01

    To compare the accuracy of 5 commonly available fine wire tensioners used in hybrid and ring external fixation. A laboratory investigation. The testing of 5 commonly available tensioners was performed with a servohydraulic test frame (MTS Bionix 858, Minneapolis, MN). The real wire tension data of each tensioner provided by the MTS were compared with corresponding nominal values. The percent error for each tensioner was calculated. Clinical ease of usage of the wire tensioners was also evaluated. The EBI tensioner was the most accurate (-0.17% to 0.09% error). The Smith and Nephew tensioner had a -13.97% to -8.61% error, the How medica tensioner a -12.48% to -10.86% error, and the Synthes tensioner a -0.2% to 24.28% error. The DePuyACE tensioner was the least accurate, with errors ranging from -36.76% to -30.92%. The Howmedica tensioner was the easiest to use, followed by the Smith and Nephew tensioner, the DePuyACE tensioner, the Synthes tensioner, and the EBI tensioner. Most commonly available tensioners tend to undertension. Future efforts should focus on the development of wire tensioners that combine accuracy and ease of usage.

  20. Hormetic effect induced by depleted uranium in zebrafish embryos

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.Y.P. [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Cheng, S.H., E-mail: bhcheng@cityu.edu.hk [Department of Biomedical Sciences, City University of Hong Kong (Hong Kong); State Key Laboratory in Marine Pollution, City University of Hong Kong (Hong Kong); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); State Key Laboratory in Marine Pollution, City University of Hong Kong (Hong Kong)

    2016-06-15

    Highlights: • Studied hormetic effect induced by uranium (U) in embryos of zebrafish (Danio rerio). • Hormesis observed at 24 hpf for exposures to 10 μg/l of depleted U (DU). • Hormesis not observed before 30 hpf for exposures to 100 μg/l of DU. • Hormetic effect induced in zebrafish embryos in a dose-and time-dependent manner. - Abstract: The present work studied the hormetic effect induced by uranium (U) in embryos of zebrafish (Danio rerio) using apoptosis as the biological endpoint. Hormetic effect is characterized by biphasic dose-response relationships showing a low-dose stimulation and a high-dose inhibition. Embryos were dechorionated at 4 h post fertilization (hpf), and were then exposed to 10 or 100 μg/l depleted uranium (DU) in uranyl acetate solutions from 5 to 6 hpf. For exposures to 10 μg/l DU, the amounts of apoptotic signals in the embryos were significantly increased at 20 hpf but were significantly decreased at 24 hpf, which demonstrated the presence of U-induced hormesis. For exposures to 100 μg/l DU, the amounts of apoptotic signals in the embryos were significantly increased at 20, 24 and 30 hpf. Hormetic effect was not shown but its occurrence between 30 and 48 hpf could not be ruled out. In conclusion, hormetic effect could be induced in zebrafish embryos in a concentration- and time-dependent manner.

  1. Evaluation of the accuracy of a veterinary dynamometric wire tensioner.

    Science.gov (United States)

    Gauthier, C M; McGilvray, K; Myrick, S; Duerr, F; Palmer, R

    2015-01-01

    The purpose of this study was to determine the accuracy of a commonly used veterinary wire tensioner. Wire tension was measured using a load cell after each of five tensioners were used to tension each of six wires to the 66, 84, and 118 mm ring settings in an adjustable custom testing fixture. Each tensioner then experienced simulated aging and testing was repeated. Percentage error was calculated for each ring size, before and after tensioner aging. Measured tension values were compared to manufacturer reported tension values for each ring size using a one-sample two-way t-test; p tension values were significantly lower for 66 mm and 84 mm rings and significantly higher for 118 mm rings, before and after simulated aging. Mean wire tension values did not significantly differ between individual wire tensioners. The tensioners tested achieved significantly different wire tension values than those reported by the manufacturer. This discrepancy could lead to under-tensioning and allowing excessive movement at a fracture site or over-tensioning, leading to wire breakage. We recommend tensioning wires at least to the recommended line on the device for 66 mm and 84 mm rings and at most to the recommended line for 118 mm rings. Further studies are needed to evaluate other veterinary wire tensioners and to develop a calibration method for these devices in practice.

  2. Ice Accretion with Varying Surface Tension

    Science.gov (United States)

    Bilanin, Alan J.; Anderson, David N.

    1995-01-01

    During an icing encounter of an aircraft in flight, super-cooled water droplets impinging on an airfoil may splash before freezing. This paper reports tests performed to determine if this effect is significant and uses the results to develop an improved scaling method for use in icing test facilities. Simple laboratory tests showed that drops splash on impact at the Reynolds and Weber numbers typical of icing encounters. Further confirmation of droplet splash came from icing tests performed in the NaSA Lewis Icing Research Tunnel (IRT) with a surfactant added to the spray water to reduce the surface tension. The resulting ice shapes were significantly different from those formed when no surfactant was added to the water. These results suggested that the droplet Weber number must be kept constant to properly scale icing test conditions. Finally, the paper presents a Weber-number-based scaling method and reports results from scaling tests in the IRT in which model size was reduced up to a factor of 3. Scale and reference ice shapes are shown which confirm the effectiveness of this new scaling method.

  3. Experimental investigation and damage assessment in a post tensioned concrete beam

    Science.gov (United States)

    Limongelli, Maria; Siegert, Dominique; Merliot, Erick; Waeytens, Julien; Bourquin, Frederic; Vidal, Roland; Le Corvec, Veronique; Guegen, Ivan; Cottineau, Louis-Marie

    2017-04-01

    This paper presents the results of an experimental campaign carried out on a prestressed concrete beam in the realm of the project SIPRIS (Systèmes Intelligents pour la Prévention des Risques Structurels), aimed to develop intelligent systems for the prevention of structural risk related to the aging of large infrastructures. The specimen was tested in several configurations aimed to re-produce several different phases of the 'life' of the beam: in the original undamaged state, under an increasing loss of tension in the cables, during and after cracking induced by a point load, after a strengthening intervention, after new cracking of the 'repaired' beam. Damage was introduced in a controlled way by means of three-point static bending tests. The transverse point loads were ap-plied at several different sections along the beam axis. Before and after each static test, the dy-namical response of the beam was measured under sine-sweep and impact tests by an extensive set of accelerometers deployed along the beam axis. The availability of both static and dynamic tests allows to investigate and compare their effectiveness to detect damages in the tensioned beam and to reliably identify the evolution of damage. The paper discusses the tests program and some results relevant to the dynamic characterization of the beam in the different phases.

  4. Evaluating prestressing strands and post-tensioning cables in concrete structures using nondestructive methods.

    Science.gov (United States)

    2015-11-01

    The objectives were to evaluate the ability of different NDE methods to detect and quantify : defects associated with corrosion of steel reinforcement and grout defects in post-tensioning : applications; and to evaluate the effectiveness of selected ...

  5. Characterization of the Dynamic Surface Tension of Aqueous Film-Forming Foam

    National Research Council Canada - National Science Library

    Hyland, Emily

    2004-01-01

    .... Additionally, the effects of varying the dilution of the AFFF concentrate by water, variation of the salinity of the water and variations in ambient temperature on the dynamic surface tension are investigated...

  6. Finite Element Analysis of Grouting Compactness Monitoring in a Post-Tensioning Tendon Duct Using Piezoceramic Transducers

    Directory of Open Access Journals (Sweden)

    Tianyong Jiang

    2017-09-01

    Full Text Available With the development of the post-tensioning technique, prestressed concrete structures have been widely used in civil engineering. To ensure the long-term effectiveness of the prestressed tendon, the grouting quality of the tendon duct is one of the important factors. However, it is still a challenge to monitor the grouting quality of post-tensioning tendon ducts, due to the invisibility of the grouting. The authors’ previous work proposed a real-time method that employed a stress wave-based active sensing approach with piezoceramic transducers to monitor the grouting compactness of a Post-Tensioning Tendon Duct (PTTD. To further understand the piezoceramic induced stress wave propagation in the PTTD with different grouting levels, this paper develops a two-dimensional finite element model for monitoring the grouting compactness of the tendon duct with a piezoceramic transducer. A smart aggregate (SA developed to utilize one Lead Zirconate Titanate (PZT transducer with marble protection is installed in the center location of the tendon duct as an actuator. Two PZT patches are bonded on the bottom and top surface of the tendon duct as the sensors. The analysis results show that the finite element analysis results are in good agreement with the experimental results, which demonstrates that the finite element analysis is feasible and reliable. For the top half of the specimen, not much stress wave could be detected before the full grouting level, except for negligible signals that may propagate through the walls of the tendon duct. When the tendon duct grouting is at 100%, the stress wave propagates to the top of the specimen, and the displacements are symmetric in both left-right and top-bottom directions before the stress waves reach the boundary. The proposed two-dimensional finite element model has the potential to be implemented to simulate the stress wave propagation principle for monitoring grouting compaction of the post-tensioning tendon

  7. Finite Element Analysis of Grouting Compactness Monitoring in a Post-Tensioning Tendon Duct Using Piezoceramic Transducers.

    Science.gov (United States)

    Jiang, Tianyong; Zheng, Junbo; Huo, Linsheng; Song, Gangbing

    2017-09-29

    With the development of the post-tensioning technique, prestressed concrete structures have been widely used in civil engineering. To ensure the long-term effectiveness of the prestressed tendon, the grouting quality of the tendon duct is one of the important factors. However, it is still a challenge to monitor the grouting quality of post-tensioning tendon ducts, due to the invisibility of the grouting. The authors' previous work proposed a real-time method that employed a stress wave-based active sensing approach with piezoceramic transducers to monitor the grouting compactness of a Post-Tensioning Tendon Duct (PTTD). To further understand the piezoceramic induced stress wave propagation in the PTTD with different grouting levels, this paper develops a two-dimensional finite element model for monitoring the grouting compactness of the tendon duct with a piezoceramic transducer. A smart aggregate (SA) developed to utilize one Lead Zirconate Titanate (PZT) transducer with marble protection is installed in the center location of the tendon duct as an actuator. Two PZT patches are bonded on the bottom and top surface of the tendon duct as the sensors. The analysis results show that the finite element analysis results are in good agreement with the experimental results, which demonstrates that the finite element analysis is feasible and reliable. For the top half of the specimen, not much stress wave could be detected before the full grouting level, except for negligible signals that may propagate through the walls of the tendon duct. When the tendon duct grouting is at 100%, the stress wave propagates to the top of the specimen, and the displacements are symmetric in both left-right and top-bottom directions before the stress waves reach the boundary. The proposed two-dimensional finite element model has the potential to be implemented to simulate the stress wave propagation principle for monitoring grouting compaction of the post-tensioning tendon duct.

  8. A Rare Side Effect of Metformin: Metformin-Induced Hepatotoxicity

    OpenAIRE

    Aksay, Ersin

    2007-01-01

    Metformin is an oral hypoglycemic agent that is commonly used in the treatment of type 2 diabetes mellitus. While metformin-associated metabolic acidosis is a widely recognized side effect of this drug, metformin-induced hepatotoxicity has been rarely reported in the literature. We present herein the case of a 52-year-old male in whom metformin-associated lactic acidosis and metformin-induced hepatotoxicity developed.

  9. Effects of Uric Acid on Exercise-induced Oxidative Stress

    OpenAIRE

    平井, 富弘

    2001-01-01

    We studied effects of uric acid on exercise― induced oxidative stress in humans based on a hypothesis that uric acid acts as an antioxidant to prevent from exercise―induced oxidative stress. Relation between uric acid level in plasma and increase of thiobarbituric acid reactive substance (TBARS)after the cycle ergometer exercise was examined. Thiobarbituricacid reactive substance in plasma increased after the ergometer exercise. High uric acid in plasma did not result in low increase of TBARS...

  10. Effects of vitamins C and E pretreatments on cadmium- induced ...

    African Journals Online (AJOL)

    GREGORY

    2010-09-27

    Sep 27, 2010 ... Animals were given single doses of vitamins C (1.5 mg/kg) and E (50 mg/kg) per oral and (0 - 8 mg Cd/kg ip) for 24 h. Animals were sacrificed and the serum ... effects of pretreatments with vitamins C and E on Cd-induced serum levels of the parameters were ... Furthermore, cadmium-induced toxicity is.

  11. Decision speed induces context effects in choice.

    NARCIS (Netherlands)

    Hawkins, G.; Brown, S.D.; Steyvers, M.; Wagenmakers, E.-J.

    2012-01-01

    The context in which a decision occurs can influence the decision-making process in many ways. In the laboratory, this is often evident in the effects of recent decisions. For instance, many experiments combine easy and difficult decisions, such as when word frequency is manipulated in lexical

  12. Ameliorative effect of ascorbic acid on mercury chloride‑induced ...

    African Journals Online (AJOL)

    Introduction: Mercury is a highly toxic metal that exerts its adverse effects on the health of humans and animals through air, soil, water and food. Aim: The present study was aimed at the evaluation of the effects of ascorbic acid on mercury chloride-induced changes on the histomorphology of the spleen of adult Wistar Rats.

  13. Kinetics of the deformation induced memory effect in polyamide-6

    NARCIS (Netherlands)

    van Drongelen, Martin; Stroeks, Alexander; Peters, Gerrit W.M.

    2015-01-01

    Nascent polyamide-6 shows a peculiar and irreversible effect; the quiescent crystallization kinetics on cooling are accelerated upon deformation in the melt, even after full relaxation of the melt. This phenomenon, known as the orientation (or better, deformation) induced memory effect of polyamide

  14. Protective effect of catalpol on isoproterenol-induced myocardial ...

    African Journals Online (AJOL)

    The neuroprotective effects of catalpol had been well demonstrated in many studies. Nevertheless, little work was done to investigate the cardioprotective effects of catalpol. This study was designed to explore whether catalpol protected myocardium against isoproterenol (ISO)-induced myocardial injury through attenuating ...

  15. Effects of Battery Voltage in Fluorescent Lamps for Use in Photovoltaic Systems; Efectos de la Tension de Bateria en Lamparas Fluorescentes para Uso en Instalaciones Fotovoltaicas

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Rosillo, F.; Egido Aguilera, M. A.

    2008-07-01

    It is known the importance of lighting systems with fluorescent lamps and electronic ballast in isolated photo-voltaic systems. The positive characteristics of the fluorescent lamps sometimes are not developed in full, due to the incorrect choice of ballast The failure of a lamp in the photovoltaic system can have great significance in the subjective perception of the user for the complete system. The purpose of this study is to analyze the behavior of two very similar fluorescent lamps, fed with different electronic ballasts, showing the great influence of the electronic ballast topology in the operation of the fluorescent lamp. In particular, this work aims to analyze the effect of variations of the input voltage to the ballast in the electrical and luminous characteristics of the lamp, as well as to understand the influence of electrical parameters in the life time of the fluorescent lamp. It is also analyzed the operating temperature of the electrode and the time necessary for electrode cooling after switching off the lamp. (Author) 23 refs.

  16. Does lipophilicity per se induce adjuvant effects?

    DEFF Research Database (Denmark)

    Hansen, Jitka Stilund; Larsen, Søren Thor; Poulsen, Lars K.

    2007-01-01

    ) or on lung function parameters. Thus, MP did not possess irritant or inflammatory properties, which may be a precursive stimulus for adjuvant effects. Second, mice were exposed to aerosols of MP, 6 or 323 mg/m3, for 1 h followed by a 20-min low-dose ovalbumin (OVA) inhalation. OVA only and OVA + Al(OH)3...... respiratory patterns were significantly affected in the MP groups. The OVA + Al(OH)3 group had a significantly higher IgG1 and IgE production, as well as higher eosinophil infiltration in the BAL fluid. These studies showed that effects of adjuvants not are necessarily due to their lipophilicity; that is......, additional structural properties are required....

  17. Inter- and intra-operator variability associated with extracapsular suture tensioning: an ex vivo study.

    Science.gov (United States)

    Dunn, A L; Buffa, E A; Marchevsky, A M; Heller, J; Moores, A P; Farrell, M

    2012-01-01

    To determine inter- and intra- operator variability associated with extracapsular suture tensioning as performed during lateral fabello-tibial suture placement. Ex vivo study. Fifteen Greyhound cadaveric pelvic limbs were prepared by cutting the cranial cruciate ligament and placing an extracapsular fabello-tibial suture. On two occasions, three surgeons tensioned the extracapsular suture of each stifle. Stifles were returned to 135 degrees of flexion and the suture tension was measured using a commercially available suture tensioner with inbuilt tensiometer. Intra-operator and inter-operator agreement were assessed using the limits of agreement method. A linear mixed effects model was specified to assess the effect of operator, repeated estimates and stifle order on tension applied. The mean difference within the three operators ranged from 0 to 14.7N. With 95% limits of agreement, on most occasions for all three operators, the difference was between -31.7 and 41.0 N. The mean difference between the three operators ranged from 6.0 to 30.7 N. With 95% limits of agreement, on most occasions the difference between operators was between -25.6 and 62.5 N. Marked variation exists in the tension applied during fabello-tibial suture application, both within and between surgeons. This variation may lead to inconsistent clinical outcomes. Further studies are required to determine the clinical consequences of this marked variation in extracapsular suture tensioning.

  18. The Tension-Stiffening Contribution of NSM CFRP to the Behavior of Strengthened RC Beams

    Directory of Open Access Journals (Sweden)

    Ahmad Azim Shukri

    2015-07-01

    Full Text Available Tension stiffening is a characteristic behavior of reinforced concrete (RC beams which is directly affected by the bond-slip property of steel bar and concrete interfaces. A beam strengthened with a near-surface mounted (NSM technique would be even more affected by tension stiffening, as the NSM reinforcement also possess a bond-slip property. Yet assessing how much the tension stiffening of NSM contributes to the behavior of RC beams is difficult due to the fact that bond-slip effects cannot be directly incorporated into a strain-based moment-curvature analysis. As such, the tension stiffening is typically incorporated through various empirical formulations, which can require a great deal of testing and calibrations to be done. In this paper a relatively new method, which can be called the mechanics-based segmental approach, is used to directly simulate the tension stiffening effect of NSM reinforcements on RC beams, without the need for empirical formulations to indirectly simulate the tension stiffening. Analysis shows that the tension stiffening of NSM fiber reinforced polymer (FRP contributes a significant portion to the stiffness and strength of the strengthened RC beam not only during serviceability, but at all load levels.

  19. The Tension-Stiffening Contribution of NSM CFRP to the Behavior of Strengthened RC Beams.

    Science.gov (United States)

    Shukri, Ahmad Azim; Darain, Kh Mahfuz Ud; Jumaat, Mohd Zamin

    2015-07-08

    Tension stiffening is a characteristic behavior of reinforced concrete (RC) beams which is directly affected by the bond-slip property of steel bar and concrete interfaces. A beam strengthened with a near-surface mounted (NSM) technique would be even more affected by tension stiffening, as the NSM reinforcement also possess a bond-slip property. Yet assessing how much the tension stiffening of NSM contributes to the behavior of RC beams is difficult due to the fact that bond-slip effects cannot be directly incorporated into a strain-based moment-curvature analysis. As such, the tension stiffening is typically incorporated through various empirical formulations, which can require a great deal of testing and calibrations to be done. In this paper a relatively new method, which can be called the mechanics-based segmental approach, is used to directly simulate the tension stiffening effect of NSM reinforcements on RC beams, without the need for empirical formulations to indirectly simulate the tension stiffening. Analysis shows that the tension stiffening of NSM fiber reinforced polymer (FRP) contributes a significant portion to the stiffness and strength of the strengthened RC beam not only during serviceability, but at all load levels.

  20. Propagation of Financial Tensions from Developed Economies to Emerging Economies

    OpenAIRE

    Mihaela-Carmen MUNTEAN; Nistor, Costel; Rozalia NISTOR; Panico, Paolo

    2011-01-01

    This paper aims to present the effect they have financial tensions in countries with developed economies on emerging economies. Because many economies have entered into recession, this has resulted in significant slowing of economic growth. The paper’s objectives are related to the presentation of the current global economic situation, the rapidity with which covered the entire world financial crisis. Also, there are presented the levels of development trade flows, financial and monetary, the...