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Sample records for vibrational induced stresses

  1. Stress wave propagation analysis on vortex-induced vibration of marine risers

    Science.gov (United States)

    Li, Hua-jun; Wang, Chao; Liu, Fu-shun; Hu, Sau-Lon James

    2017-03-01

    To analyze the stress wave propagation associated with the vortex-induced vibration (VIV) of a marine riser, this paper employed a multi-signal complex exponential method. This method is an extension of the classical Prony's method which decomposes a complicated signal into a number of complex exponential components. Because the proposed method processes multiple signals simultaneously, it can estimate the "global" dominating frequencies (poles) shared by those signals. The complex amplitude (residues) corresponding to the estimated frequencies for those signals is also obtained in the process. As the signals were collected at different locations along the axial direction of a marine riser, the phenomena of the stress wave propagation could be analyzed through the obtained residues of those signals. The Norwegian Deepwater Program (NDP) high mode test data were utilized in the numerical studies, including data sets in both the in-line (IL) and cross-flow (CF) directions. It was found that the most dominant component in the IL direction has its stress wave propagation along the riser being dominated by a standing wave, while that in the CF direction dominated by a traveling wave.

  2. Man-Induced Vibrations

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Hansen, Lars Pilegaard

    1994-01-01

    concerned with spectator-induced vertical vibrations on grandstands. The idea is to use impulse response analysis and base the load description on the load impulse. If the method is feasable, it could be used in connection with the formulation of requirements in building codes. During the last two decades...... work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

  3. Stress analysis of vibrating pipelines

    Science.gov (United States)

    Zachwieja, Janusz

    2017-03-01

    The pipelines are subject to various constraints variable in time. Those vibrations, if not monitored for amplitude and frequency, may result in both the fatigue damage in the pipeline profile at high stress concentration and the damage to the pipeline supports. If the constraint forces are known, the system response may be determined with high accuracy using analytical or numerical methods. In most cases, it may be difficult to determine the constraint parameters, since the industrial pipeline vibrations occur due to the dynamic effects of the medium in the pipeline. In that case, a vibration analysis is a suitable alternative method to determine the stress strain state in the pipeline profile. Monitoring the pipeline vibration levels involves a comparison between the measured vibration parameters and the permissible values as depicted in the graphs for a specific pipeline type. Unfortunately, in most cases, the studies relate to the petrochemical industry and thus large diameter, long and straight pipelines. For a pipeline section supported on both ends, the response in any profile at the entire section length can be determined by measuring the vibration parameters at two different profiles between the pipeline supports. For a straight pipeline section, the bending moments, variable in time, at the ends of the analysed section are a source of the pipe excitation. If a straight pipe section supported on both ends is excited by the bending moments in the support profile, the starting point for the stress analysis are the strains, determined from the Euler-Bernoulli equation. In practice, it is easier to determine the displacement using the experimental methods, since the factors causing vibrations are unknown. The industrial system pipelines, unlike the transfer pipelines, are straight sections at some points only, which makes it more difficult to formulate the equation of motion. In those cases, numerical methods can be used to determine stresses using the

  4. Evaluation of Flow-Induced Dynamic Stress and Vibration of Volute Casing for a Large-Scale Double-Suction Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Fu-Jun Wang

    2013-01-01

    Full Text Available The transient analysis was carried out to investigate the dynamic stress and vibration of volute casing for a large double-suction centrifugal pump by using the transient fluid-structure interaction theory. The flow pulsations at flow rate ranging from 60% to 100% of the nominal flow rate (Qd were taken as the boundary conditions for FEM analysis of the pump volute casing structure. The results revealed that, for all operating conditions, the maximum stress located at the volute tongue region, whereas the maximum vibration displacement happened close to the shaft hole region. It was also found that the blade passing frequency and its harmonics were dominant in the variations of dynamic stress and vibration displacement. The amplitude of the dominant frequency for the maximum stress detected at 0.6 Qd was 1.14 times that at Qd, lower than the related difference observed for pressure fluctuations (3.23 times. This study provides an effective method to quantify the flow-induced structural dynamic characteristics for a large-scale double-suction pump. It can be used to direct the hydraulic and structural design and stable operation, as well as fatigue life prediction for large-scale pumps.

  5. Chaotic vortex induced vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Sheridan, J. [Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Victoria 3800 (Australia); Leontini, J. S. [Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Lo Jacono, D. [Institut de Mécanique des Fluides de Toulouse (IMFT), CNRS, UPS and Université de Toulouse, 31400 Toulouse (France)

    2014-12-15

    This study investigates the nature of the dynamic response of an elastically mounted cylinder immersed in a free stream. A novel method is utilized, where the motion of the body during a free vibration experiment is accurately recorded, and then a second experiment is conducted where the cylinder is externally forced to follow this recorded trajectory. Generally, the flow response during both experiments is identical. However, particular regimes exist where the flow response is significantly different. This is taken as evidence of chaos in these regimes.

  6. Stress-anneal-induced magnetic anisotropy in highly textured Fe-Ga and Fe-Al magnetostrictive strips for bending-mode vibrational energy harvesters

    Directory of Open Access Journals (Sweden)

    Jung Jin Park

    2016-05-01

    Full Text Available Magnetostrictive Fe-Ga and Fe-Al alloys are promising materials for use in bending-mode vibrational energy harvesters. For this study, 50.8 mm × 5.0 mm × 0.5 mm strips of Fe-Ga and Fe-Al were cut from 0.50-mm thick rolled sheet. An atmospheric anneal was used to develop a Goss texture through an abnormal grain growth process. The anneal lead to large (011 grains that covered over 90% of sample surface area. The resulting highly-textured Fe-Ga and Fe-Al strips exhibited saturation magnetostriction values (λsat =  λ∥ − λ⊥ of ∼280 ppm and ∼130 ppm, respectively. To maximize 90° rotation of magnetic moments during bending of the strips, we employed compressive stress annealing (SA. Samples were heated to 500°C, and a 100-150 MPa compressive stress was applied while at 500°C for 30 minutes and while being cooled. The effectiveness of the SA on magnetic moment rotation was inferred by comparing post-SA magnetostriction with the maximum possible yield of rotated magnetic moments, which is achieved when λ∥ = λsat and λ⊥ = 0. The uniformity of the SA along the sample length and the impact of the SA on sensing/energy harvesting performance were then assessed by comparing pre- and post-SA bending-stress-induced changes in magnetization at five different locations along the samples. The SA process with a 150 MPa compressive load improved Fe-Ga actuation along the sample length from 170 to 225 ppm (from ∼60% to within ∼80% of λsat. The corresponding sensing/energy harvesting performance improved by as much as a factor of eight in the best sample, however the improvement was not at all uniform along the sample length. The SA process with a 100 MPa compressive load improved Fe-Al actuation along the sample length from 60 to 73 ppm (from ∼46% to ∼56% of λsat, indicating only a marginally effective SA and suggesting the need for modification of the SA protocol. In spite of this, the SA was effective at improving the sensing

  7. Prediction of induced vibrations in stall

    Energy Technology Data Exchange (ETDEWEB)

    Thirstrup Petersen, J.; Thomsen, K.; Aagaard Madsen, H. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    The main results from recent research in stall induced vibrations are presented. The focus is on the edgewise blade vibrations, which during the last decade have turned out to be a potential threat against the stable operation of stall regulated wind turbines and a fact, which must be dealt with by the designer. The basic physical explanation for the phenomenon and examples of design precaution, which can be taken, are presented. (au)

  8. Stochastic analysis of self-induced vibrations

    DEFF Research Database (Denmark)

    Rüdinger, Finn; Krenk, Steen

    2002-01-01

    Vortex-induced vibrations of a structurl element are modelled as a non-linear stochastic single-degree-of-freedom system. The deterministic part of the governing equation represents laminar flow conditions with a stationary non-zero solution corresponding to lock-in. Across-wind turbulence...

  9. Hubungan Phantom Vibration Syndrome Terhadap Sleep Disorder dan Kondisi Stress

    Directory of Open Access Journals (Sweden)

    Ajeng Yeni Setianingrum

    2017-10-01

    Full Text Available Phantom vibration syndrome is a condition where a person would feel the sensation of vibration of a cell phone as if there were incoming notification but the fact is not. This research investigated the relationship between phantom vibration syndromes, sleep disorder and stress condition. Questionnaires were distributed to 120 participants with age range 18 to 23 years old. Data of participants showed that all of participants using a smart mobile phone and 24% of them have more than one cell phone. Time usage of cell phone is at least 1 hour. 23% of participants using a cell phone for social media activity, followed by 21% related to entertainment (music, video and games. The results showed a positive relationship between phantom vibration syndrome, sleep disorder and stress condition. Insomnia contributed a greater influence on stress condition. However, the phantom vibration syndrome is more directly affecting the sleep apnea compared to insomnia and stress condition. Therefore, the phantom vibration syndrome more affects stress condition indirectly, through sleep disorder (sleep apnea and insomnia. Consequently, phantom vibration syndrome has a strong relationship with stress condition at the time of the phantom vibration syndrome can cause sleep disorder.

  10. Hubungan Phantom Vibration Syndrome Terhadap Sleep Disorder dan Kondisi Stress

    OpenAIRE

    Ajeng Yeni Setianingrum

    2017-01-01

    Phantom vibration syndrome is a condition where a person would feel the sensation of vibration of a cell phone as if there were incoming notification but the fact is not. This research investigated the relationship between phantom vibration syndromes, sleep disorder and stress condition. Questionnaires were distributed to 120 participants with age range 18 to 23 years old. Data of participants showed that all of participants using a smart mobile phone and 24% of them have more than one cell p...

  11. Alleviation of Buffet-Induced Vibration Using Piezoelectric Actuators

    National Research Council Canada - National Science Library

    Morgenstern, Shawn D

    2006-01-01

    .... The objective of this research was to determine the most critical natural modes of vibration for the F-16 ventral fin and design piezoelectric actuators capable of reducing buffet-induced ventral fin vibration...

  12. Experimental Study of Pressure Drop and Wall Shear Stress Characteristics of γ /Al2O3-Water Nanofluid in a Circular pipe under Turbulent flow induced vibration.

    Directory of Open Access Journals (Sweden)

    Adil Abbas AL-Moosawy

    2016-09-01

    Full Text Available Experimental study of γ /Al2O3 with mean diameter of less than 50 nm was dispersed in the distilled water that flows through a pipe consist of five sections as work station ,four sections made of carbon steel metal and one sections made of Pyrex glass pipe, with five nanoparticles volume concentrations of 0%,0.1%,0.2%,0.3%,and 0.4% with seven different volume flow rates 100, 200 , 300, 400, 500, 600 ,and 700ℓ/min were investigated to calculated pressure distribution for the cases without rubber ,with 3mm rubber and with 6mm rubber used to support the pipe. Reynolds number was between 20000 and 130000. Frequency value through pipe was measured for all stations of pipe for all cases. The results show that the pressure drop and wall shear stress of the nanofluid increase by increasing the nanoparticles volume concentrations or Reynolds number, the values of frequency through the pipe increase continuously when wall shear stress increases and the ratio of increment increases as nanofluid concentrations increase. Increasing of vibration frequency lead to increasing the friction factor between the pipe and the wall and thus increasing in pressure drop. Several equations between the wall shear stress and frequency for all volume concentration and for three cases without rubber, with rubber has 3mm thickness ,and with rubber has 6mm thickness. Finally, the results led to that γ /Al2O3 could function as a good and alternative conventional working fluid in heat transfer applications. A good agreement is seen between the experimental and those available in the literature

  13. Induced Current Measurement of Rod Vibrations

    Science.gov (United States)

    Sawicki, Charles A.

    2003-01-01

    The longitudinal normal modes of vibration of rods are similar to the modes seen in pipes open at both ends. A maximum of particle displacement exists at both ends and an integral number (n) of half wavelengths fit into the rod length. The frequencies fn of the normal modes is given by Eq. (1), where L is the rod length and V is the wave velocity: fn = nV/2L. Many methods have been used to measure the velocity of these waves. The Kundt's tube method commonly used in student labs will not be discussed here. A simpler related method has been described by Nicklin.2 Kluk3 measured velocities in a wide range of materials using a frequency counter and microphone to study sounds produced by impacts. Several earlier methods4,5 used phonograph cartridges complete with needles to detect vibrations in excited rods. A recent interesting experiment6 used wave-induced changes in magnetization produced in an iron rod by striking one end. The travel time, measured as the impulsive wave reflects back and forth, gave the wave velocity for the iron rod. In the method described here, a small magnet is attached to the rod with epoxy, and vibrations are detected using the current induced in a few loops of wire. The experiment is simple and yields very accurate velocity values.

  14. Study on residual stresses in ultrasonic torsional vibration assisted micro-milling

    Science.gov (United States)

    Lu, Zesheng; Hu, Haijun; Sun, Yazhou; Sun, Qing

    2010-10-01

    It is well known that machining induced residual stresses can seriously affect the dimensional accuracy, corrosion and wear resistance, etc., and further influence the longevity and reliability of Micro-Optical Components (MOC). In Ultrasonic Torsional Vibration Assisted Micro-milling (UTVAM), cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank are the main factors which affect residual stresses. A 2D model of UTVAM was established with FE analysis software ABAQUS. Johnson-Cook's flow stress model and shear failure principle are used as the workpiece material model and failure principle, while friction between tool and workpiece uses modified Coulomb's law whose sliding friction area is combined with sticking friction. By means of FEA, the influence rules of cutting parameters, vibration parameters, mill cutter parameters, the status of wear length of tool flank on residual stresses are obtained, which provides a basis for choosing optimal process parameters and improving the longevity and reliability of MOC.

  15. Field Investigations On the Lateral Vibration Features Of Prestressed Concrete Stress Ribbon Footbridges

    Directory of Open Access Journals (Sweden)

    Fukada Saiji

    2015-01-01

    Full Text Available The prestressed concrete (PC stress ribbon footbridge is a type of suspension bridge without towers, which has been applied in Japan and all over the world for years in light of its low construction cost and aesthetic merit. It generally consists of the precast concrete slabs with embedded cables. However, the walking-induced lateral vibration trouble of the Millennium Bridge in London in 2000 gave a lesson to the engineers that the lateral vibration feature must be taken into consideration for the footbridge vibration evaluation. In this sense, the field investigations on the lateral vibration features of 14 pre-stressed concrete stress ribbon footbridge in Japan was carried out by artificial impact and damping free vibration tests. According to the investigations, the larger the bridge span, the lower the frequencies of lateral-related vibration modes. In addition, based on the damping-free vibration field tests, there was a tendency toward the damping constant degradation when bridge span became larger.

  16. Induced vibrations facilitate traversal of cluttered obstacles

    Science.gov (United States)

    Thoms, George; Yu, Siyuan; Kang, Yucheng; Li, Chen

    When negotiating cluttered terrains such as grass-like beams, cockroaches and legged robots with rounded body shapes most often rolled their bodies to traverse narrow gaps between beams. Recent locomotion energy landscape modeling suggests that this locomotor pathway overcomes the lowest potential energy barriers. Here, we tested the hypothesis that body vibrations induced by intermittent leg-ground contact facilitate obstacle traversal by allowing exploration of locomotion energy landscape to find this lowest barrier pathway. To mimic a cockroach / legged robot pushing against two adjacent blades of grass, we developed an automated robotic system to move an ellipsoidal body into two adjacent beams, and varied body vibrations by controlling an oscillation actuator. A novel gyroscope mechanism allowed the body to freely rotate in response to interaction with the beams, and an IMU and cameras recorded the motion of the body and beams. We discovered that body vibrations facilitated body rolling, significantly increasing traversal probability and reducing traversal time (P probability increased with and traversal time decreased with beam separation. These results confirmed our hypothesis and support the plausibility of locomotion energy landscapes for understanding the formation of locomotor pathways in complex 3-D terrains.

  17. Post-stressed concrete foundation may reduce machinery vibration

    Science.gov (United States)

    Fistedis, S. H.

    1967-01-01

    Post-stressing concrete mat foundation reduces excessive vibrations in machinery. The mat is stressed in compression after the machinery is mounted, thus closing any cracks in it, altering the distribution of the soil subgrade reaction on the mat, and changing the mat-subgrade natural frequency.

  18. Vibrations and alternated stresses in turbomachineries; Vibrations et contraintes alternees dans les turbomachines

    Energy Technology Data Exchange (ETDEWEB)

    Naudin, M. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)]|[FRAMATOME, 92 - Paris-La-Defense (France); Pugnet, J.M. [Conservatoire National des Arts et Metiers (CNAM), Grenoble-1 Univ., 38 (France)]|[FRAMATOME, 92 - Paris-La-Defense (France)

    1999-07-01

    Vibration phenomena are sources of mechanical incidents in turbomachineries. A calculation of the Eigenmodes of machine parts and a knowledge of their possible excitation during the machine operation can greatly improve the reliability and availability of the equipments. The development of computer tools and in particular the use of finite-element codes has allowed a more and more precise calculation of Eigenmodes and Eigenfrequencies. However, the analysis of excitation sources remains sometimes insufficient to explain and anticipate some complex vibrational phenomena encountered in rotative machines. The aim of this paper is to present, using two different examples, the methodology to be used in order to perform a complete vibrational analysis of mechanical components. The following aspects are reviewed successively: 1 - the damped vibrational system: study of the free motion, study of the response to an harmonic forced excitation; 2 - vibrational analysis of turbine blades: steam turbine blades, Eigenmodes of mobile blades, excitation sources, Campbell diagram, calculation of static and dynamical stresses, Haigh diagram, acceptance criteria and safety coefficient, influence of corrosion; 3 - dynamical analysis of the bending of a lineshaft: different flexion Eigenmodes, stiffness and damping of bearings, calculation of flexion Eigenmodes, excitation sources, vibrational stability of the lineshaft and vibration level; 3 - generalization: vibration of blades, shaft dynamics, alternative machines. (J.S.) 10 refs.

  19. Stress-induced cardiomyopathy.

    Science.gov (United States)

    Boland, Torrey A; Lee, Vivien H; Bleck, Thomas P

    2015-03-01

    Reversible stress-induced cardiac dysfunction is frequently seen as a complication of a multitude of acute stress states, in particular neurologic injuries. This dysfunction may be difficult to distinguish between that caused by myocardial ischemia and may impact both the treatment strategies and prognosis of the underlying condition. Critical care practitioners should have an understanding of the epidemiology, pathophysiology, clinical characteristics, precipitating conditions, differential diagnosis, and proposed treatments for stress-induced cardiomyopathy. MEDLINE database search conducted from inception to August 2014, including the search terms "tako-tsubo," "stress-induced cardiomyopathy," "neurogenic cardiomyopathy," "neurogenic stress cardiomyopathy," and "transient left ventricular apical ballooning syndrome". In addition, references from pertinent articles were used for a secondary search. After review of peer-reviewed original scientific articles, guidelines, and reviews resulting from the literature search described above, we made final selections for included references and data based on relevance and author consensus. Stress-induced cardiomyopathy occurs most commonly in postmenopausal women. It can be precipitated by emotional stress, neurologic injury, and numerous other stress states. Patients may present with symptoms indistinguishable from acute coronary syndrome or with electrocardiogram changes and wall motion abnormalities on echocardiogram following neurologic injury. Nearly all patients will have an elevated cardiac troponin. The underlying etiology is likely related to release of catecholamines, both locally in the myocardium and in the circulation. Differential diagnosis includes myocardial infarction, myocarditis, neurogenic pulmonary edema, and nonischemic cardiomyopathy. Although the natural course of stress-induced cardiomyopathy is resolution, treatment strategies include sympathetic blockade and supportive care. Stress-induced

  20. Strategy for predicting railway-induced vibrations in buildings

    DEFF Research Database (Denmark)

    Persson, Peter; Persson, Kent; Andersen, Lars Vabbersgaard

    2016-01-01

    for the residents. It is necessary, even at an early stage of planning, to assess the extent of the vibrations and state requirements for the building in order to avoid costly changes at later stages. Ground vibration induced by railway traffic is studied in the paper. The aim is to develop a strategy...... for predicting vibrations in nearby buildings in an early stage of the building process. The strategy is based on that there is a fairly good knowledge of the properties of the ground and that some on-site vibration measurements are made. By combining these with finite-element analysis, the vibration level...... a strategy for predicting railway-induced vibrations....

  1. Airflow induced vibration of the Si-IT prototype

    CERN Document Server

    Dijkstra, H; De Aguiar, V; Rigo, V

    2014-01-01

    In this note we present the results of air-flow induced vibration tests performed on mechanical prototypes of the Si option of the Inner Tracker upgrade. We made a modal analyze where we observed the eigenfrequency of the Si-ladder structure at ∼30 Hz as previously measured at CERN. Flowing dry-air to cool the prototypes we do not observe a lock-in state of the vortex induced vibration (VIV). The maximum observed vibration amplitude is calculated. We conclude that the VIV excites the eigenfrequency almost independently from the air-flow speed, and with an amplitude which does not damage the structure.

  2. Distinct Skeletal Muscle Gene Regulation from Active Contraction, Passive Vibration, and Whole Body Heat Stress in Humans.

    Directory of Open Access Journals (Sweden)

    Michael A Petrie

    Full Text Available Skeletal muscle exercise regulates several important metabolic genes in humans. We know little about the effects of environmental stress (heat and mechanical stress (vibration on skeletal muscle. Passive mechanical stress or systemic heat stress are often used in combination with many active exercise programs. We designed a method to deliver a vibration stress and systemic heat stress to compare the effects with active skeletal muscle contraction.The purpose of this study is to examine whether active mechanical stress (muscle contraction, passive mechanical stress (vibration, or systemic whole body heat stress regulates key gene signatures associated with muscle metabolism, hypertrophy/atrophy, and inflammation/repair.Eleven subjects, six able-bodied and five with chronic spinal cord injury (SCI participated in the study. The six able-bodied subjects sat in a heat stress chamber for 30 minutes. Five subjects with SCI received a single dose of limb-segment vibration or a dose of repetitive electrically induced muscle contractions. Three hours after the completion of each stress, we performed a muscle biopsy (vastus lateralis or soleus to analyze mRNA gene expression.We discovered repetitive active muscle contractions up regulated metabolic transcription factors NR4A3 (12.45 fold, PGC-1α (5.46 fold, and ABRA (5.98 fold; and repressed MSTN (0.56 fold. Heat stress repressed PGC-1α (0.74 fold change; p < 0.05; while vibration induced FOXK2 (2.36 fold change; p < 0.05. Vibration similarly caused a down regulation of MSTN (0.74 fold change; p < 0.05, but to a lesser extent than active muscle contraction. Vibration induced FOXK2 (p < 0.05 while heat stress repressed PGC-1α (0.74 fold and ANKRD1 genes (0.51 fold; p < 0.05.These findings support a distinct gene regulation in response to heat stress, vibration, and muscle contractions. Understanding these responses may assist in developing regenerative rehabilitation interventions to improve muscle cell

  3. Flow-Induced Vibration of Circular Cylindrical Structures

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shoei-Sheng [Argonne National Lab. (ANL), Argonne, IL (United States). Components Technology Division

    1985-06-01

    Flow-induced vibration is a term to denote those phenomena associated with the response of structures placed in or conveying fluid flow. More specifically, the terra covers those cases in which an interaction develops between fluid-dynamic forces and the inertia, damping or elastic forces in the structures. The study of these phenomena draws on three disciplines: (1) structural mechanics, (2) mechanical vibration, and (3) fluid dynamics. The vibration of circular cylinders subject to flow has been known to man since ancient times; the vibration of a wire at its natural frequency in response to vortex shedding was known in ancient Greece as aeolian tones. But systematic studies of the problem were not made until a century ago when Strouhal established the relationship between vortex shedding frequency and flow velocity for a given cylinder diameter. The early research in this area has beer summarized by Zdravkovich (1985) and Goldstein (1965). Flow-induced structural vibration has been experienced in numerous fields, including the aerospace industry, power generation/transmission (turbine blades, heat exchanger tubes, nuclear reactor components), civil engineering (bridges, building, smoke stacks), and undersea technology. The problems have usually been encountered or created accidentally through improper design. In most cases, a structural or mechanical component, designed to meet specific objectives, develops problems when the undesired effects of flow field have not been accounted for in the design. When a flow-induced vibration problem is noted in the design stage, the engineer has different options to eliminate the detrimental vibration. Unfortunately, in many situations, the problems occur after the components are already in operation; the "fix" usually is very costly. Flow-induced vibration comprises complex and diverse phenomena; subcritical vibration of nuclear fuel assemblies, galloping of transmission lines, flutter of pipes conveying fluid, and whirling

  4. Optimum vibrating beams with stress and deflection constraints

    Science.gov (United States)

    Kamat, M. P.

    1976-01-01

    The fundamental frequency of vibration of an Euler-Bernoulli or a Timoshenko beam of a specified constant volume is maximized subject to the constraint that under a prescribed loading the maximum stress or maximum deflection at any point along the beam axis will not exceed a specified value. In contrast with the inequality constraint which controls the minimum cross-section, the present inequality constraints lead to more meaningful designs. The inequality constraint on stresses is as easily implemented as the minimum cross-section constraint but the inequality constraint on deflection uses a treatment which is an extension of the matrix partitioning technique of prescribing displacements in finite element analysis.

  5. Concorde Noise-Induced Building Vibrations, Montgomery County, Maryland

    Science.gov (United States)

    Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Finley, T. D.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

    1976-01-01

    A series of studies are reported to assess the noise induced building vibrations associated with Concorde operations. The levels of induced vibration and associated indoor/outdoor noise levels resulting from aircraft and nonaircraft events in selected homes, historic and other buildings near Dulles International Airport were recorded. The building response resulting from aircraft operations was found to be directly proportional to the overall sound pressure level and approximately independent of the aircraft type. The noise levels and, consequently, the response levels were observed to be higher for the Concorde operations than for the CTOL operations. Furthermore, the vibration could be closely reproduced by playing aircraft noise through a loudspeaker system located near the vibration measurement location. Nonaircraft events such as door closing were again observed to result in higher response levels than those induced by aircraft.

  6. Evolution of microstructure and residual stress under various vibration modes in 304 stainless steel welds.

    Science.gov (United States)

    Hsieh, Chih-Chun; Wang, Peng-Shuen; Wang, Jia-Siang; Wu, Weite

    2014-01-01

    Simultaneous vibration welding of 304 stainless steel was carried out with an eccentric circulating vibrator and a magnetic telescopic vibrator at subresonant (362 Hz and 59.3 Hz) and resonant (376 Hz and 60.9 Hz) frequencies. The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process. During simultaneous vibration welding primary δ -ferrite can be refined and the morphologies of retained δ-ferrite become discontinuous so that δ-ferrite contents decrease. The smallest content of δ-ferrite (5.5%) occurred using the eccentric circulating vibrator. The diffraction intensities decreased and the FWHM widened with both vibration and no vibration. A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency. The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.

  7. First international symposium on Flow Induced Noise and Vibration Issues and Aspects

    CERN Document Server

    Rosa, Sergio; Franco, Francesco; Guyader, Jean-Louis; Hambric, Stephen; Flinovia - Flow Induced Noise and Vibration Issues and Aspects

    2015-01-01

    Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. It describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation;
for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays;
for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements;
for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses. This book p...

  8. Attenuation of cryocooler induced vibration in spaceborne infrared payloads

    Science.gov (United States)

    Veprik, A.; Twitto, A.

    2014-01-01

    Recent advancement of operational responsive space programs calls for a development of compact, reliable, low power and vibration free cryogenic cooling for sophisticated infrared payloads. The refrigeration in a typical closed cycle split Stirling linear cryocooler is achieved by a cyclic compression and expansion of a gaseous working agent due to a synchronized reciprocation of electro-dynamically and pneumatically actuated compressor and expander pistons. Attenuation of the cryocooler induced vibration usually relies on the concept of actively assisted momentum cancellation. In a typical dual-piston compressor this objective is achieved by actively synchronizing the motion of oppositely moving piston assemblies; a typical single-piston expander may be counterbalanced by a motorized counter-balancer. The above approach produces complexity, weight, size, high incurred costs and affects reliability. The authors analyze the case of passive attenuation the vibration export induced by the split Stirling linear cryocooler comprised of inline mounted single-piston compressor and expander. Placement of all the moving components onto a common axis results in a single axis consolidation of vibration export and enables use of single tuned dynamic absorber and low frequency vibration mount. From theoretical analysis and full-scale testing, the performance of such vibration protection arrangement is similar to known systems of active vibration cancellation.

  9. Measuring unbalance-induced vibrations in rotating tools

    Directory of Open Access Journals (Sweden)

    Kimmelmann Martin

    2017-01-01

    Full Text Available Unbalances in a tool cause vibrations of the spindle and the machine itself and lead to a waviness of the machined workpiece surface. This paper presents an experimental and analytical procedure for optically measuring the unbalance-induced displacements of the tool centre point (TCP. Therefore, a new method is introduced to determine the dynamic vibrations of a tool by comparing the geometrical profile of the tool with the dynamical profile at a high rotational speed. The necessary steps for measuring the signals and calculating the underlying dynamic vibrations of the tool are presented here. Afterwards, the unbalance-induced vibrations of a milling tool are shown as well as their influence on the eccentricity of the rotation axis. With this newly introduced method it is possible to directly link the displacements of the tool under rotation to the waviness of the workpiece surface and the dynamic stiffness of machine tools.

  10. Wind-induced vibration of stay cables

    Science.gov (United States)

    2007-08-01

    Cable-stayed bridges have become the form of choice over the past several decades for bridges in the medium- to long-span range. In some cases, serviceability problems involving large amplitude vibrations of stay cables under certain wind and rain co...

  11. Fatigue Failure Results for Multi-Axial versus Uniaxial Stress Screen Vibration Testing

    Directory of Open Access Journals (Sweden)

    Wayne E. Whiteman

    2002-01-01

    Full Text Available To date, the failure potential and prediction between simultaneous multi-axial versus sequentially applied uniaxial vibration stress screen testing has been the subject of great debate. In most applications, current vibration tests are done by sequentially applying uniaxial excitation to the test specimen along three orthogonal axes. The most common standards for testing military equipment are published in MIL-STD-810F and NAVMAT P-9492. Previous research had shown that uniaxial testing may be unrealistic and inadequate. This current research effort is a continuing effort to systematically investigate the differences between fatigue damage mechanisms and the effects of uniaxial versus tri-axial testing. This includes assessing the ability of the tri-axial method in predicting the formation of damage mechanisms, specifically looking at the effects of stress or fatigue failure. Multi-axial testing achieves the synergistic effect of exciting all modes simultaneously and induces a more realistic vibration stress loading condition. As such, it better approximates real-world operating conditions. This paper provides the latest results on the differences between multi-axial and uniaxial testing of a simple notched cantilever beam.

  12. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    DEFF Research Database (Denmark)

    Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

    2016-01-01

    We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples fro...... and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces....

  13. Flow-induced vibrations an engineering guide

    CERN Document Server

    Naudascher, Eduard

    2012-01-01

    Despite their variety, the vibration phenomena from many different engineering fields can be classified into a relatively few basic excitation mechanisms. The classification enables engineers to identify all possible sources of excitation in a given system and to assess potential dangers. This graduate-level text presents a synthesis of research results and practical experience from disparate fields in the form of engineering guidelines. It is particularly geared toward assessing the possible sources of excitation in a flow system, in identifying the actual danger spots, and in finding appropr

  14. Low Head, Vortex Induced Vibrations River Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Bernitsas, Michael B.; Dritz, Tad

    2006-06-30

    Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.

  15. Evaluation of blast-induced vibration effects on structures 1

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Rim; Jeon, Gyu Shick; Lee, Dae Soo; Joo, Kwang Ho; Lee, Woong Keon [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of); Ryu, Chang Ha; Chung, So Keul; Lee, Kyung Won; Shin, Hee Soon; Chun, Sun Woo; Park, Yeon Jun; Synn, Joong Ho; Choi, Byung Hee [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

    1995-12-31

    Due to the difficulties of obtaining construction site for new plants, following ones are inevitably being built in the site adjacent to existing power plants. Therefore considerable thought has been recently given to the dynamic loading generated by blasting works near the plants to maintain the safety of structures and facilities in power plants. Our own standard for safety level of blast vibration is not prepared yet, and foreign standards have been generally employed without theoretical and experimental verification. Safety-related structures of power plants and facilities have to be protected against the effects of possible hazards due to blast vibration. Earthquakes have been considered a major dynamic design loading as a requirement of plant design, but the effects of blast-induced vibration are not. In order to ensure the safety, rational safe criterion should be established and blast design should be satisfy it, which requires the development of a model for prediction of vibration level through more systematic measurement and analysis. The main objectives of the study are : to provide background data for establishing the rational safe vibration limits, to develop models for prediction of blast vibration level, to establish safe blast design criterion, and to accumulate techniques for field measurements, data acquisition and analysis (author). 80 refs., 347 figs.

  16. Reducing friction-induced vibration using intelligent active force ...

    Indian Academy of Sciences (India)

    (FIV). Thus, it should be reduced or controlled as much as possible in order to achieve quieter vehicle (brake system), better performance (position control systems and clutches) and quality products. There were typically three major mechanisms that contributing to the generation of friction induced vibration namely: negative ...

  17. Modelling flow-induced vibrations of gates in hydraulic structures

    NARCIS (Netherlands)

    Erdbrink, C.D.

    2014-01-01

    The dynamic behaviour of gates in hydraulic structures caused by passing flow poses a potential threat to flood protection. Complex interactions between the turbulent flow and the suspended gate body may induce undesired vibrations. This thesis contributes to a better understanding and prevention of

  18. Laser-induced vibrational dynamics of ozone in solid argon

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

    1997-01-01

    We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...

  19. Predicting vibration-induced displacement for a resonant friction slider

    DEFF Research Database (Denmark)

    Fidlin, A.; Thomsen, Jon Juel

    2001-01-01

    A mathematical model is set up to quantify vibration-induced motions of a slider, sandwiched between friction layers with different coefficients of friction, and equipped with an imbedded resonator that oscillates at high frequency and small amplitude. This model is highly nonlinear, involving no...

  20. Train induced vibrations in geosynthetic reinforced railway embankments

    DEFF Research Database (Denmark)

    Zania, Varvara; Hededal, Ole; Krogsbøll, Anette

    2011-01-01

    High–speed trains may generate ground vibrations which cause undesirable environmental and economical impacts such as nuisance of the passengers, deflections along the rail, and possibly impairment of the stability of the embankments. The increase of the velocity of a moving load on homogeneous...... includes usually the application of stabilization techniques like geosynthetic reinforcement. Hence, in the current study the ground vibration, which is induced by a train passage in geosynthetic reinforced embankments, is investigated. In addition the impact of the soil conditions is examined. In order...

  1. Stress and free vibration analyses of multilayered composite plates

    Science.gov (United States)

    Noor, Ahmed K.; Burton, W. Scott

    1989-01-01

    This paper presents a two-phase computational procedure for the accurate prediction of vibration frequencies, stresses, and deformations in simply supported bidirectional multilayered composite plates. The range of applicability of this procedure in terms of the plate's parameters is determined, and the potential of the proposed procedure for use in conjunction with large-scale finite element modeling of composite structures is discussed. It is shown that the use of the shear correction factors calculated by this procedure extends the range of the validity of the first-order shear deformation theory, used in the first phase of the procedure, to fairly thick multilayered plates with the h/L1 ratio of the order of 0.3.

  2. A hybrid-stress finite element approach for stress and vibration analysis in linear anisotropic elasticity

    Science.gov (United States)

    Oden, J. Tinsley; Fly, Gerald W.; Mahadevan, L.

    1987-01-01

    A hybrid stress finite element method is developed for accurate stress and vibration analysis of problems in linear anisotropic elasticity. A modified form of the Hellinger-Reissner principle is formulated for dynamic analysis and an algorithm for the determination of the anisotropic elastic and compliance constants from experimental data is developed. These schemes were implemented in a finite element program for static and dynamic analysis of linear anisotropic two dimensional elasticity problems. Specific numerical examples are considered to verify the accuracy of the hybrid stress approach and compare it with that of the standard displacement method, especially for highly anisotropic materials. It is that the hybrid stress approach gives much better results than the displacement method. Preliminary work on extensions of this method to three dimensional elasticity is discussed, and the stress shape functions necessary for this extension are included.

  3. A unified solution for vibration analysis of plates with general structural stress distributions

    Directory of Open Access Journals (Sweden)

    Nian Yang

    2016-11-01

    Full Text Available Complex stress distributions often exist in ocean engineering structures. This stress influences structural vibrations. Finite Element Methods exhibit some shortcomings for solving non-uniform stress problems, such as an unclear physical interpretation, complicated operation, and large number of computations. Analytical methods research considers mainly uniform stress problems, and often, their methods cannot be applied in practical marine structures with non-uniform stress. In this paper, an analytical method is proposed to solve the vibration of plates with general stress distributions. Non-uniform stress is expressed as a special series, and the stress influence is inserted into a vibration equation that is solved through decoupling to obtain an analytical solution. This method has been verified using numerical examples and can be used in arbitrary stress distribution cases. This method requires fewer computations and it provides a clearer physical interpretation, so it has advantages in some qualitative research.

  4. Streaming Induced by Ultrasonic Vibration in a Water Vessel

    Science.gov (United States)

    Nomura, Shinfuku; Murakami, Koichi; Sasaki, Yuuichi

    2000-06-01

    The flow pattern induced by ultrasonic vibration in a water vessel is investigated experimentally using several liquids. In tap water, vortex streaming of cavitation bubbles around the pressure node of a standing wave occurred because of the large number of cavitation bubbles generated by the ultrasonic vibration. Acoustic streaming of the Rayleigh type caused by cavitation bubble streaming is also induced in tap water. In a glycerin aqueous solution of 30%, Eckart streaming, which flowed upward from the vibrator, occurred due to the dissipation of ultrasonic energy caused by viscosity. On the other hand, in degassed water, streaming is hardly generated at all since a uniform and stable standing wave is formed in the water vessel. The velocity of the acoustic streaming generated in the water vessel by 27.8 kHz vibration is 1 to 6 mm/s. The cavitation bubble streaming in tap water is completely independent of normal Rayleigh or Eckart streaming. This bubble streaming is considerably faster than previous streaming.

  5. Pedestrian-induced lateral vibrations of footbridges

    DEFF Research Database (Denmark)

    Ingólfsson, Einar Thór

    and the frequency of the lateral movement. These forces are self-excited in the sense that they are generated by the movement of the body’s centre of mass, which in turn is caused by the lateral acceleration of the underlying pavement. Due to the random nature of the human-induced loadings and a large scatter...

  6. Flow-induced vibration of component cooling water heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Y.S.; Chen, S.S. (Taiwan Power Co., Taipei (Taiwan). Nuclear Engineering Dept.; Argonne National Lab., IL (USA))

    1990-01-01

    This paper presents an evaluation of flow-induced vibration problems of component cooling water heat exchangers in one of Taipower's nuclear power stations. Specifically, it describes flow-induced vibration phenomena, tests to identify the excitation mechanisms, measurement of response characteristics, analyses to predict tube response and wear, various design alterations, and modifications of the original design. Several unique features associated with the heat exchangers are demonstrated, including energy-trapping modes, existence of tube-support-plate (TSP)-inactive modes, and fluidelastic instability of TSP-active and -inactive modes. On the basis of this evaluation, the difficulties and future research needs for the evaluation of heat exchangers are identified. 11 refs., 19 figs., 3 tabs.

  7. Stress Analysis of Rotary Vibration of Rigid Friction Pile and Stress General Solution of Central Symmetry Plane Elastic Problem

    OpenAIRE

    Fu-yao Zhao; Er-xiang Song; Jun Yang

    2015-01-01

    The rotary vibration of rigid friction pile can be seen approximately as a central symmetry plane problem in elasticity. The stress general solution of central symmetry plane problem in elasticity can be constructed by technique such as the Laurent expansion of the volume force. This solution has some decoupling, generalized, and convergent properties, and it can be used in stress analysis of the rotary vibration of pile. The analysis results show that the maximum value of displacement will n...

  8. Evaluation of human-induced vibration of continuous footbridges

    Directory of Open Access Journals (Sweden)

    El-Robaa Ahmed

    2015-01-01

    Full Text Available With the development of construction materials and the introduction of high strength steel and concrete, the human-induced vibration became a dominant criterion for the design of pedestrian bridges. Currently, longer spans and lightweight bridges have been comprised in most of design trends. This leads to lower the natural frequencies of the system which have a great effect on the dynamic performance of bridges subjected to human activities. Although the design of steel footbridges could reach the optimum level of design in terms of strength criterion, it might not reach the acceptance level for vibration condition. This will enforce the designer to choose section profiles with higher inertia to enhance stiffness of the whole system. This paper presents an overall assessment for floor vibration problem due to pedestrian induced vertical forces on continuous composite footbridges. The footfall method presented by concrete centre “CCIP-016” is adopted in this study to evaluate the response factor and acceleration of pedestrian bridges using a FEA software package “Robot Structural Analysis”.

  9. Experimental and analytical studies on pedestrian induced footbridge vibrations

    DEFF Research Database (Denmark)

    Gudmundsson, Gudmundur Valur; Ingólfsson, Einar Thór; Einarsson, Baldvin

    2007-01-01

    This paper presents results from experimental study on human-induced vibrations of three lively footbridges in Reykjavik. The project was funded by the Icelandic Public Roads Administration with two main focus areas; validating the FE-models used at the design stage in terms of dynamic characteri......This paper presents results from experimental study on human-induced vibrations of three lively footbridges in Reykjavik. The project was funded by the Icelandic Public Roads Administration with two main focus areas; validating the FE-models used at the design stage in terms of dynamic...... with two equal spans crossing the same highway and was built in 2000. A commercially available finite element program (SAP2000) was used in the design phase to model the bridges. The FE-models were updated after the initial tests in order to have the frequencies and damping of the fundamental vibration...... modes corresponding to the measured values. The models were subsequently used to calculate the predicted acceleration according to the preliminary version of the Eurocode (ENV 1992-2: Concrete bridges) using time-history analysis with a moving load as representative for a single pedestrian. The load...

  10. Hydroxyurea-Induced Replication Stress

    Directory of Open Access Journals (Sweden)

    Kenza Lahkim Bennani-Belhaj

    2010-01-01

    Full Text Available Bloom's syndrome (BS displays one of the strongest known correlations between chromosomal instability and a high risk of cancer at an early age. BS cells combine a reduced average fork velocity with constitutive endogenous replication stress. However, the response of BS cells to replication stress induced by hydroxyurea (HU, which strongly slows the progression of replication forks, remains unclear due to publication of conflicting results. Using two different cellular models of BS, we showed that BLM deficiency is not associated with sensitivity to HU, in terms of clonogenic survival, DSB generation, and SCE induction. We suggest that surviving BLM-deficient cells are selected on the basis of their ability to deal with an endogenous replication stress induced by replication fork slowing, resulting in insensitivity to HU-induced replication stress.

  11. Attenuation of cryocooler induced vibration using multimodal tuned dynamic absorber

    Science.gov (United States)

    Veprik, A.; Babitsky, V.; Tuito, A.

    2017-12-01

    Modern infrared imagers often rely on low Size, Weight and Power split Stirling linear cryocoolers comprised of side-by-side packed compressor and expander units fixedly mounted upon a common frame and interconnected by the configurable transfer line. Imbalanced reciprocation of moving assemblies generates vibration export in the form of tonal force couple producing angular and translational dynamic responses. Resulting line of sight jitter and dynamic defocusing may affect the image quality. The authors explore the concept of multimodal tuned dynamic absorber, the translational and tilting modal frequencies of which are essentially matched to the driving frequency. Dynamic analysis and full-scale testing show that the dynamic reactions (forces and moments) produced by such a device may effectively attenuate both translational and angular components of cryocooler-induced vibration.

  12. Laser-induced vibration of a thin soap film.

    Science.gov (United States)

    Emile, Olivier; Emile, Janine

    2014-09-21

    We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

  13. Experimental chaotic quantification in bistable vortex induced vibration systems

    Science.gov (United States)

    Huynh, B. H.; Tjahjowidodo, T.

    2017-02-01

    The study of energy harvesting by means of vortex induced vibration systems has been initiated a few years ago and it is considered to be potential as a low water current energy source. The energy harvester is realized by exposing an elastically supported blunt structure under water flow. However, it is realized that the system will only perform at a limited operating range (water flow) that is attributed to the resonance phenomenon that occurs only at a frequency that corresponds to the fluid flow. An introduction of nonlinear elements seems to be a prominent solution to overcome the problem. Among many nonlinear elements, a bistable spring is known to be able to improve the harvested power by a vortex induced vibrations (VIV) based energy converter at the low velocity water flows. However, it is also observed that chaotic vibrations will occur at different operating ranges that will erratically diminish the harvested power and cause a difficulty in controlling the system that is due to the unpredictability in motions of the VIV structure. In order to design a bistable VIV energy converter with improved harvested power and minimum negative effect of chaotic vibrations, the bifurcation map of the system for varying governing parameters is highly on demand. In this study, chaotic vibrations of a VIV energy converter enhanced by a bistable stiffness element are quantified in a wide range of the governing parameters, i.e. damping and bistable gap. Chaotic vibrations of the bistable VIV energy converter are simulated by utilization of a wake oscillator model and quantified based on the calculation of the Lyapunov exponent. Ultimately, a series of experiments of the system in a water tunnel, facilitated by a computer-based force-feedback testing platform, is carried out to validate the existence of chaotic responses. The main challenge in dealing with experimental data is in distinguishing chaotic response from noise-contaminated periodic responses as noise will smear

  14. Does stress induce salt intake?

    Science.gov (United States)

    Torres, Susan J; Turner, Anne I; Nowson, Caryl A

    2010-06-01

    Psychological stress is a common feature of modern day societies, and contributes to the global burden of disease. It was proposed by Henry over 20 years ago that the salt intake of a society reflects the level of stress, and that stress, through its effect on increasing salt intake, is an important factor in the development of hypertension. This review evaluates the evidence from animal and human studies to determine if stress does induce a salt appetite and increase salt consumption in human subjects. Findings from animal studies suggest that stress may drive salt intake, with evidence for a potential mechanism via the sympatho-adrenal medullary system and/or the hypothalamo-pituitary-adrenal axis. In contrast, in the few laboratory studies conducted in human subjects, none has found that acute stress affects salt intake. However, one study demonstrated that life stress (chronic stress) was associated with increased consumption of snack foods, which included, but not specifically, highly salty snacks. Studies investigating the influence of chronic stress on eating behaviours are required, including consumption of salty foods. From the available evidence, we can conclude that in free-living, Na-replete individuals, consuming Na in excess of physiological requirements, stress is unlikely to be a major contributor to salt intake.

  15. Vortex-induced vibration of a slender single-span cylinder

    NARCIS (Netherlands)

    Oikou, N.

    2014-01-01

    The goal of this paper is to study the vortex-induced vibration of slender cylindrical structures. For this purpose, a 2D model that calculates the coupled cross-flow and in-line vibrations of a flexible single span beam is developed. A wake oscillator known to match well with free vibration

  16. Effect of Blast-Induced Vibration from New Railway Tunnel on Existing Adjacent Railway Tunnel in Xinjiang, China

    Science.gov (United States)

    Liang, Qingguo; Li, Jie; Li, Dewu; Ou, Erfeng

    2013-01-01

    The vibrations of existing service tunnels induced by blast-excavation of adjacent tunnels have attracted much attention from both academics and engineers during recent decades in China. The blasting vibration velocity (BVV) is the most widely used controlling index for in situ monitoring and safety assessment of existing lining structures. Although numerous in situ tests and simulations had been carried out to investigate blast-induced vibrations of existing tunnels due to excavation of new tunnels (mostly by bench excavation method), research on the overall dynamical response of existing service tunnels in terms of not only BVV but also stress/strain seemed limited for new tunnels excavated by the full-section blasting method. In this paper, the impacts of blast-induced vibrations from a new tunnel on an existing railway tunnel in Xinjiang, China were comprehensively investigated by using laboratory tests, in situ monitoring and numerical simulations. The measured data from laboratory tests and in situ monitoring were used to determine the parameters needed for numerical simulations, and were compared with the calculated results. Based on the results from in situ monitoring and numerical simulations, which were consistent with each other, the original blasting design and corresponding parameters were adjusted to reduce the maximum BVV, which proved to be effective and safe. The effect of both the static stress before blasting vibrations and the dynamic stress induced by blasting on the total stresses in the existing tunnel lining is also discussed. The methods and related results presented could be applied in projects with similar ground and distance between old and new tunnels if the new tunnel is to be excavated by the full-section blasting method.

  17. Improved assumed-stress hybrid shell element with drilling degrees of freedom for linear stress, buckling, and free vibration analyses

    Science.gov (United States)

    Rengarajan, Govind; Aminpour, Mohammad A.; Knight, Norman F., Jr.

    1992-01-01

    An improved four-node quadrilateral assumed-stress hybrid shell element with drilling degrees of freedom is presented. The formulation is based on Hellinger-Reissner variational principle and the shape functions are formulated directly for the four-node element. The element has 12 membrane degrees of freedom and 12 bending degrees of freedom. It has nine independent stress parameters to describe the membrane stress resultant field and 13 independent stress parameters to describe the moment and transverse shear stress resultant field. The formulation encompasses linear stress, linear buckling, and linear free vibration problems. The element is validated with standard tests cases and is shown to be robust. Numerical results are presented for linear stress, buckling, and free vibration analyses.

  18. Antioxidant-Induced Stress

    Science.gov (United States)

    Villanueva, Cleva; Kross, Robert D.

    2012-01-01

    Antioxidants are among the most popular health-protecting products, sold worldwide without prescription. Indeed, there are many reports showing the benefits of antioxidants but only a few questioning the possible harmful effects of these “drugs”. The normal balance between antioxidants and free radicals in the body is offset when either of these forces prevails. The available evidence on the harmful effects of antioxidants is analyzed in this review. In summary, a hypothesis is presented that “antioxidant-induced stress” results when antioxidants overwhelm the body’s free radicals. PMID:22408440

  19. Antioxidant-Induced Stress

    Directory of Open Access Journals (Sweden)

    Robert D. Kross

    2012-02-01

    Full Text Available Antioxidants are among the most popular health-protecting products, sold worldwide without prescription. Indeed, there are many reports showing the benefits of antioxidants but only a few questioning the possible harmful effects of these “drugs”. The normal balance between antioxidants and free radicals in the body is offset when either of these forces prevails. The available evidence on the harmful effects of antioxidants is analyzed in this review. In summary, a hypothesis is presented that “antioxidant-induced stress” results when antioxidants overwhelm the body’s free radicals.

  20. Wave-induced Ship Hull Vibrations in Stochastic Seaways

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Dogliani, M.

    1996-01-01

    A theoretical Study is undertaken on the determination of wave-induced loads in flexible ship hulls. The calculations are performed within the framework of a non-linear, quadratic strip theory formulated in the frequency domain. Included are non-linear effects due to changes in added mass......, hydrodynamic damping and water line breadth with sectional immersion in waves. The study is limited to continuous excitations from the waves and thus transient so-called whipping vibrations due to slamming loads are not considered.Because of the non-linearities the ship hull responses become non...... to the large separation between dominating wave frequencies and the lowest two-node frequency of the hull beam. Both extreme value predictions and fatigue damage are considered.For a fast container ship the rigid body and two-node (springing) vertical wave-induced bending moments amidship are calculated...

  1. STABILITY AND NATURAL VIBRATIONS OF INHOMOGENEOUS SHELLS TAKING INTO ACCOUNT THE STRESS STATE

    Directory of Open Access Journals (Sweden)

    Bazhenov V.A.

    2015-12-01

    Full Text Available The work is devoted to the problem of developing a unified methodology based on the efficient numerical analysis of problems of stability and natural vibrations of a wide class of inhomogeneous shells, thin and medium thickness. In problems of its natural vibrations takes into account the presence of a pre-stressed state of the structure from the action of static loads, which significantly affect the spectrum of natural vibrations and allows determining the bifurcation point and the value of the critical force of buckling by dynamic criteria.

  2. Modeling and Mechanism of Rain-Wind Induced Vibration of Bundled Conductors

    Directory of Open Access Journals (Sweden)

    Chao Zhou

    2016-01-01

    Full Text Available Under the certain rain-wind conditions, bundled conductors exhibit a rain-wind induced large-amplitude vibration. This type of vibration can cause the fatigue fractures of conductors and fatigue failures of spacers, which threaten the safety operation and serviceability of high-voltage transmission line. To reveal the mechanism of rain-wind induced vibration of bundled conductors, a series of 2-dimensional CFD models about the twin bundled conductors with rivulets are developed to obtain the curves of aerodynamic coefficients with the upper rivulet angle. The influences of the forward conductor’s aerodynamic shielding and the upper rivulet’s aerodynamic characteristics on the leeward conductor are discussed. Furthermore, a 2-dimensional 3DOF model for the rain-wind induced vibration of the leeward conductor is established. The model is solved by finite element method and Newmark method, and the effects of the wind velocity and the upper rivulet’s motion on vibration amplitude of the leeward conductor are analyzed. By contrast with the wake-induced vibration, it can easily find that the characteristics of rain-wind vibration are obviously different from those of the wake-induced vibration, and the main reason of the rain-induced vibration may be due to the upper rivulet’s motion.

  3. Exact Vibration Solution for initially stressed Beams resting on ...

    African Journals Online (AJOL)

    It is observed that, as the values of these structural parameters increase, the transverse deflections of the finite elastic beam under the actions of moving masses decreases. Furthermore, the conditions under which the vibrating systems will experience resonance phenomenon are highlighted. Results presented in this paper ...

  4. A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping.

    Science.gov (United States)

    Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu

    2014-02-01

    In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

  5. Neuromuscular fatigue induced by whole-body vibration exercise.

    Science.gov (United States)

    Maffiuletti, Nicola A; Saugy, Jonas; Cardinale, Marco; Micallef, Jean-Paul; Place, Nicolas

    2013-06-01

    The aim of this study was to examine the magnitude and the origin of neuromuscular fatigue induced by half-squat static whole-body vibration (WBV) exercise, and to compare it to a non-WBV condition. Nine healthy volunteers completed two fatiguing protocols (WBV and non-WBV, randomly presented) consisting of five 1-min bouts of static half-squat exercise with a load corresponding to 50 % of their individual body mass. Neuromuscular fatigue of knee and ankle muscles was investigated before and immediately after each fatiguing protocol. The main outcomes were maximal voluntary contraction (MVC) torque, voluntary activation, and doublet peak torque. Knee extensor MVC torque decreased significantly (P fatiguing protocols. Doublet peak torque decreased significantly and to a similar extent following WBV and non-WBV exercise, for both knee extensors (-25 %; P fatigue and did not change its causative factors compared to non-WBV half-squat resistive exercise in recreationally active subjects.

  6. Dynamic Characteristics of Flow Induced Vibration in a Rotor-Seal System

    Directory of Open Access Journals (Sweden)

    Nan Zhang

    2011-01-01

    Full Text Available Flow induced vibration is an important factor affecting the performance of the rotor-seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the fluid force, which is induced by the interaction between the unstable fluid flow in the seal and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear models. Various nonlinear phenomena of flow induced vibration in the rotor-seal system, such as synchronization phenomenon and amplitude mutation, are reproduced.

  7. Enhancement of Energy Harvesting Performance by a Coupled Bluff Splitter Body and PVEH Plate through Vortex Induced Vibration near Resonance

    Directory of Open Access Journals (Sweden)

    Wei Ken Chin

    2017-09-01

    Full Text Available Inspired by vortex induced vibration energy harvesting development as a new source of renewable energy, a T-shaped design vibration energy harvester is introduced with the aim of enhancing its performance through vortex induced vibration at near resonance conditions. The T-shaped structural model designed consists of a fixed boundary aluminum bluff splitter body coupled with a cantilever piezoelectric vibration energy harvesters (PVEH plate model which is a piezoelectric bimorph plate made of a brass plate sandwiched between 2 lead zirconate titanate (PZT plates. A 3-dimensional Fluid-Structure Interaction simulation analysis is carried out with Reynolds Stress Turbulence Model under wind speed of 7, 10, 12, 14, 16, 18, 19, 20, 22.5, and 25 m/s. The results showed that with 19 m/s wind speed, the model generates 75.758 Hz of vortex frequency near to the structural model’s natural frequency of 76.9 Hz. Resonance lock-in therefore occurred, generating a maximum displacement amplitude of 2.09 mm or a 49.76% increment relatively in vibrational amplitude. Under the effect of resonance at the PVEH plate’s fundamental natural frequency, it is able to generate the largest normalized power of 13.44 mW/cm3g2.

  8. The effects of pre-exercise vibration stimulation on the exercise-induced muscle damage.

    Science.gov (United States)

    Kim, Ji-Yun; Kang, Da-Haeng; Lee, Joon-Hee; O, Se-Min; Jeon, Jae-Keun

    2017-01-01

    [Purpose] To investigate the effects of pre-induced muscle damage vibration stimulation on the pressure-pain threshold and muscle-fatigue-related metabolites of exercise-induced muscle damage. [Subjects and Methods] Thirty healthy, adult male subjects were randomly assigned to the pre-induced muscle damage vibration stimulation group, post-induced muscle damage vibration stimulation group, or control group (n=10 per group). To investigate the effects of pre-induced muscle damage vibration stimulation, changes in the pressure-pain threshold (lb), creatine kinase level (U/L), and lactate dehydrogenase level (U/L) were measured and analyzed at baseline and at 24 hours, 48 hours, and 72 hours after exercise. [Results] The pressure-pain thresholds and concentrations of creatine kinase and lactate dehydrogenase varied significantly in each group and during each measurement period. There were interactions between the measurement periods and groups, and results of the post-hoc test showed that the pre-induced muscle damage vibration stimulation group had the highest efficacy among the groups. [Conclusion] Pre-induced muscle damage vibration stimulation is more effective than post-induced muscle damage vibration stimulation for preventing muscle damage.

  9. Characterization of Train-Induced Vibration and its Effect on Fecal Corticosterone Metabolites in Mice.

    Science.gov (United States)

    Atanasov, Nicholas A; Sargent, Jennifer L; Parmigiani, John P; Palme, Rupert; Diggs, Helen E

    2015-11-01

    Excessive environmental vibrations can have deleterious effects on animal health and experimental results, but they remain poorly understood in the animal laboratory setting. The aims of this study were to characterize train-associated vibration in a rodent vivarium and to assess the effects of this vibration on the reproductive success and fecal corticosterone metabolite levels of mice. An instrumented cage, featuring a high-sensitivity microphone and accelerometer, was used to characterize the vibrations and sound in a vivarium that is near an active railroad. The vibrations caused by the passing trains are 3 times larger in amplitude than are the ambient facility vibrations, whereas most of the associated sound was below the audible range for mice. Mice housed in the room closest to the railroad tracks had pregnancy rates that were 50% to 60% lower than those of mice of the same strains but bred in other parts of the facility. To verify the effect of the train vibrations, we used a custom-built electromagnetic shaker to simulate the train-induced vibrations in a controlled environment. Fecal pellets were collected from male and female mice that were exposed to the simulated vibrations and from unexposed control animals. Analysis of the fecal samples revealed that vibrations similar to those produced by a passing train can increase the levels of fecal corticosterone metabolites in female mice. These increases warrant attention to the effects of vibration on mice and, consequently, on reproduction and experimental outcomes.

  10. Vibration induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers

    Science.gov (United States)

    Eger, Tammy; Thompson, Aaron; Leduc, Mallorie; Krajnak, Kristine; Goggins, Katie; Godwin, Alison; House, Ron

    2015-01-01

    BACKGROUND Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk of vibration-induced injury. PARTICIPANTS Workers who operated locomotives (n = 3), bolting platforms (n = 10), jumbo drills (n = 7), raise drilling platforms (n = 4), and crushers (n = 3), participated. METHODS A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury. PMID:24004754

  11. Vibration-induced PM Noise in Oscillators and Measurements of Correlation with Vibration Sensors

    National Research Council Canada - National Science Library

    Howe, D. A; LanFranchi, J. L; Cutsinger, L; Hati, A; Nelson, C

    2005-01-01

    ...) and acceleration/vibration sensors. We describe the equipment setup and measurement procedure. Data are in the form of scatter plots, which we find to be highly informative compared to usual L(f...

  12. Abnormal vibration induced illusion of movement in essential tremor: evidence for abnormal muscle spindle afferent function

    OpenAIRE

    Frima, N; Grunewald, R

    2005-01-01

    Objectives: Vibration induced illusion of movement (VIIM) is abnormal in patients with idiopathic focal dystonia, an abnormality which corrects with fatigue of the vibrated muscle. Since dystonia and essential tremor sometimes coexist in families, we investigated the perception of VIIM and the effect of fatigue on VIIM in patients with essential tremor.

  13. Fatigue failure in metal bellows due to flow-induced vibrations

    Science.gov (United States)

    Daniels, C. M.; Fargo, C. G.

    1969-01-01

    To prevent fatigue due to flow-induced vibrations in metal bellows connected to ducts carrying liquid hydrogen, a study was made which shows that the flexure lines are in general a function of the vibration coupling between the fluid and bellows structure, and the nature of the external environment.

  14. Influence of local geological pattern on values of vibrations induced by road traffic

    Science.gov (United States)

    Kaláb, Zdeněk; Lednická, Markéta; Kořínek, Robert; Hrubešová, Eva

    2012-04-01

    Buildings in the proximity of roads can be affected by vibrations induced by traffic. Local geological pattern is necessary to be taken into account because it has significant influence on values of vibrations and their characteristics. This paper summarizes results of experimental measurements. Four different types of buildings in different types of local geology were used for this purpose. The obtained results document that the generation of significant vibrations is mostly due to heavy vehicles. Some maximum velocity values exceed acceptable limits according to the Czech Technical Standard 73 0040 for evaluation of technical seismicity effect on buildings. Cosmetic damage, meaning the cracking of plaster, might occur due to traffic vibrations.

  15. Wind-induced Vibrations in the European Court Towers

    DEFF Research Database (Denmark)

    Hansen, Jannick B.; Brincker, Rune; Andersen, Ken G.

    2012-01-01

    Issues regarding occupancy comfort in vibration-sensitive structures are the motivation of this study concerning windinduced vibrations in the European Court Towers in Luxembourg. In one of the two identical towers tuned liquid dampers (TLD) have been installed. Recent studies investigate the cha...

  16. Subsurface melting of nylon by friction-induced vibrations

    NARCIS (Netherlands)

    Vroegop, P.H.; Bosma, R.

    1985-01-01

    Dry sliding of nylon on steel may lead to subsurface recrystallization of the polymer. This phenomenon is described and explained by subsurface melting due to internal heating as a result of the dissipation of frictioninduced vibrations at frequencies above 10 kHz. A vibration model relating the

  17. Vortex-Induced Vibration of a Cable-Stayed Bridge

    Directory of Open Access Journals (Sweden)

    M. T. Song

    2016-01-01

    Full Text Available The dynamic response of a cable-stayed bridge that consists of a simply supported four-cable-stayed deck beam and two rigid towers, subjected to a distributed vortex shedding force on the deck beam with a uniform rectangular cross section, is studied in this work. The cable-stayed bridge is modeled as a continuous system, and the distributed vortex shedding force on the deck beam is modeled using Ehsan-Scanlan’s model. Orthogonality conditions of exact mode shapes of the linearized undamped cable-stayed bridge model are employed to convert coupled governing partial differential equations of the original cable-stayed bridge model with damping to a set of ordinary differential equations by using Galerkin method. The dynamic response of the cable-stayed bridge is calculated using Runge-Kutta-Felhberg method in MATLAB for two cases with and without geometric nonlinear terms. Convergence of the dynamic response from Galerkin method is investigated. Numerical results show that the geometric nonlinearities of stay cables have significant influence on vortex-induced vibration of the cable-stayed bridge. There are different limit cycles in the case of neglecting the geometric nonlinear terms, and there are only one limit cycle and chaotic responses in the case of considering the geometric nonlinear terms.

  18. FLOW-INDUCED VIBRATION IN PIPES: CHALLENGESS AND SOLUTIONS - A REVIEW

    Directory of Open Access Journals (Sweden)

    M. SIBA

    2016-03-01

    Full Text Available The Flow-induced vibration has recently been the topic of experimental, numerical, and theoretical studies. It was intended to implement better applications for controlling the flow using orifice technique. Having the flow under control, the orifice becomes an instrument for measuring the flow. The flow of all fluid such as water, oil, gas and vapours through an orifice was tested and mathematical models were developed adequately. The basic theme for these enormous studies was the need for the very accurate flow measurements through orifices. All experimental, theoretical, numerical, and analytical studies have agreed that there is more than one avenue to develop, modify, and enhance such measurements. However, one factor that affects the flow measurements is the vibration which was not treated as required until the mid-20th century due to enormous discoveries that damages could be rooted to vibration. Researchers have studied vibration and then proposed mathematical models in conjunction with the pressure and velocity measurements of the flowing fluids and then the effect of the vibration, induced or not induced, has been under continuous investigation. This paper is an attempt to review the previous studies regarding understanding the nature of the vibration and the possible effects of vibration on the flow and on the piping structure in order to limit the damage caused by the vibration. This study shows that the need for more experimental studies and more comprehensive analytical approaches are, in particular, very essential to develop better results.

  19. A Comparative Study of Ground and Underground Vibrations Induced by Bench Blasting

    Directory of Open Access Journals (Sweden)

    Xiuzhi Shi

    2016-01-01

    Full Text Available Ground vibrations originating from bench blasting may cause damage to slopes, structures, and underground workings in close proximity to an operating open-pit mine. It is important to monitor and predict ground vibration levels induced by blasting and to take measures to reduce their hazardous effects. The aims of this paper are to determine the weaker protection objects by comparatively studying bench blasting induced vibrations obtained at surface and in an underground tunnel in an open-pit mine and thus to seek vibration control methods to protect engineering objects at the site. Vibrations arising from measurement devices at surface and in an underground tunnel at the Zijinshan Open-Pit Mine were obtained. Comparative analysis of the peak particle velocities shows that, in the greatest majority of cases, surface values are higher than underground values for the same vibration distance. The transmission laws of surface and underground vibrations were established depending on the type of rock mass, the explosive charge, and the distance. Compared with the Chinese Safety Regulations for Blasting (GB6722-2014, the bench blasting induced vibrations would not currently cause damage to the underground tunnel. According to the maximum allowable peak particle velocities for different objects, the permitted maximum charges per delay are obtained to reduce damage to these objects at different distances.

  20. Topographic analysis of the skull vibration-induced nystagmus test with piezoelectric accelerometers and force sensors.

    Science.gov (United States)

    Dumas, Georges; Lion, Alexis; Perrin, Philippe; Ouedraogo, Evariste; Schmerber, Sébastien

    2016-03-23

    Vibration-induced nystagmus is elicited by skull or posterior cervical muscle stimulations in patients with vestibular diseases. Skull vibrations delivered by the skull vibration-induced nystagmus test are known to stimulate the inner ear structures directly. This study aimed to measure the vibration transfer at different cranium locations and posterior cervical regions to contribute toward stimulus topographic optimization (experiment 1) and to determine the force applied on the skull with a hand-held vibrator to study the test reproducibility and provide recommendations for good clinical practices (experiment 2). In experiment 1, a 100 Hz hand-held vibrator was applied on the skull (vertex, mastoids) and posterior cervical muscles in 11 healthy participants. Vibration transfer was measured by piezoelectric sensors. In experiment 2, the vibrator was applied 30 times by two experimenters with dominant and nondominant hands on a mannequin equipped to measure the force. Experiment 1 showed that after unilateral mastoid vibratory stimulation, the signal transfer was higher when recorded on the contralateral mastoid than on the vertex or posterior cervical muscles (Pvibration transfer was measured on vertex and posterior cervical muscles. Experiment 2 showed that the force applied to the mannequin varied according to the experimenters and the handedness, higher forces being observed with the most experienced experimenter and with the dominant hand (10.3 ± 1.0 and 7.8 ± 2.9 N, respectively). The variation ranged from 9.8 to 29.4% within the same experimenter. Bone transcranial vibration transfer is more efficient from one mastoid to the other mastoid than other anatomical sites. The mastoid is therefore the optimal site for skull vibration-induced nystagmus test in patients with unilateral vestibular lesions and enables a stronger stimulation of the healthy side. In clinical practice, the vibrator should be placed on the mastoid and should be held by the clinician

  1. Flow induced vibrations of the CLIC X-Band accelerating structures

    CERN Document Server

    Charles, Tessa; Boland, Mark; Riddone, Germana; Samoshkin, Alexandre

    2011-01-01

    Turbulent cooling water in the Compact Linear Collider (CLIC) accelerating structures will inevitably induce some vibrations. The maximum acceptable amplitude of vibrations is small, as vibrations in the accelerating structure could lead to beam jitter and alignment difficulties. A Finite Element Analysis model is needed to identify the conditions under which turbulent instabilities and significant vibrations are induced. Due to the orders of magnitude difference between the fluid motion and the structure’s motion, small vibrations of the structure will not contribute to the turbulence of the cooling fluid. Therefore the resonant conditions of the cooling channels presented in this paper, directly identify the natural frequencies of the accelerating structures to be avoided under normal operating conditions. In this paper a 2D model of the cooling channel is presented finding spots of turbulence being formed from a shear layer instability. This effect is observed through direct visualization and wavelet ana...

  2. Analysis of flow-induced vibrations in turbomachinery by mapping of complex fluid pressures

    Directory of Open Access Journals (Sweden)

    N Wirth

    2016-10-01

    Full Text Available In this paper we introduce a mapping procedure which facilitates the simulation of flow-induced vibrations in turbomachinery. The transient steady state pressure fluctuations in the flow field (which excite vibrations are computed in the frequency domain by what are generally referred to as “harmonic CFD” methods where the pressure oscillations are expressed by complex amplitudes. They are mapped using the Fraunhofer software FSIMapper to a structural vibration analysis. A main focus lies in the provision of mapping methods for cyclic symmetric models. The process provides a fast numerical assessment of flow-induced vibrations where the resulting vibration amplitudes can be used for realistic fatigue estimations of flow-excited turbine components. The procedure is applied to a ceramic impeller of a micro gas turbine.

  3. Influence of the pavement surface on the vibrations induced by heavy traffic in road bridges

    National Research Council Canada - National Science Library

    Paje, S.E; Vázquez, V.F; Camara, A; Ruiz-Teran, A.M

    2017-01-01

    The irregularity of the pavement surface governs the traffic-induced vibrations in road bridges, but it is either ignored or simulated by means of ideal pavements that differ significantly from real cases...

  4. Floor Vibrations - as Induced and Reduced by Humans

    DEFF Research Database (Denmark)

    Pedersen, Lars

    . As for dynamic loads focus is placed on heel impact excitation and actions of jumping people causing floor vibrations. As for interaction between stationary humans and the vibrating floor focus is on modelling humans as oscillating spring-mass-damper systems attached to the floor rather than as simple added mass...... on the effectiveness of tuned mass dampers fitted to floors carrying humans is further examined....

  5. Imaging the surface stress and vibration modes of a microcantilever by laser beam deflection microscopy.

    Science.gov (United States)

    Tamayo, Javier; Pini, Valerio; Kosaka, Prisicila; Martinez, Nicolas F; Ahumada, Oscar; Calleja, Montserrat

    2012-08-10

    There is a need for noninvasive techniques for simultaneous imaging of the stress and vibration mode shapes of nanomechanical systems in the fields of scanning probe microscopy, nanomechanical biological and chemical sensors and the semiconductor industry. Here we show a novel technique that combines a scanning laser, the beam deflection method and digital multifrequency excitation and analysis for simultaneous imaging of the static out-of-plane displacement and the shape of five vibration modes of nanomechanical systems. The out-of-plane resolution is at least 100 pm Hz⁻¹/² and the lateral resolution, which is determined by the laser spot size, is 1-1.5 μm. The capability of the technique is demonstrated by imaging the residual surface stress of a microcantilever together with the shape of the first 22 vibration modes. The vibration behavior is compared with rigorous finite element simulations. The technique is suitable for major improvements in the imaging of liquids, such as higher bandwidth and enhanced spatial resolution.

  6. Stress Analysis of Rotary Vibration of Rigid Friction Pile and Stress General Solution of Central Symmetry Plane Elastic Problem

    Directory of Open Access Journals (Sweden)

    Fu-yao Zhao

    2015-01-01

    Full Text Available The rotary vibration of rigid friction pile can be seen approximately as a central symmetry plane problem in elasticity. The stress general solution of central symmetry plane problem in elasticity can be constructed by technique such as the Laurent expansion of the volume force. This solution has some decoupling, generalized, and convergent properties, and it can be used in stress analysis of the rotary vibration of pile. The analysis results show that the maximum value of displacement will not occur at the edge of the pile and the assumption that pile cross section remains unchanged is no longer applicable, if the value of one dimensionless quantity, reflecting the angular frequency of the rotation, radius, and material properties of the pile, is larger than 1.84. Once the rotary vibration of rigid friction pile happens, the pile may lose its bearing capacity under the comprehensive effect of normal and shear stress of the pile-soil interface and it will be very difficult to recover.

  7. Vibration induced sliding: theory and experiment for a beam with a spring-loaded mass

    DEFF Research Database (Denmark)

    Miranda, Erik; Thomsen, Jon Juel

    1998-01-01

    The study sets up a simple model for predicting vibration induced sliding of mass, and provides quantitative experimental evidence for the validity of the model. The results lend confidence to recent theoretical developments on using vibration induced sliding for passive vibration damping......, and contributes to a further understanding of this nonlinear phenomenon. A mathematical model is set up to describe vibration induced sliding for a base-excited cantilever beam with a spring-loaded pointmass. Approximations simplify the model into two nonlinear ordinary differential equations, describing motions...... of the system at near-resonant excitation of a single beam mode. This simplified model is studied numerically and analytically, and tested against laboratory experiments. The experiments provide evidence that the simplified mathematical model retains those features of the real system that are necessary...

  8. Noise-Induced Building Vibrations Caused by Concorde and Conventional Aircraft Operations at Dulles and Kennedy International Airports

    Science.gov (United States)

    Mayes, W. H.; Stephens, D. G.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Ward, D. W.; Deloach, R.; Cawthorn, J. M.; Finley, T. D.; Lynch, J. W.

    1978-01-01

    Outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded, as were the associated vibration levels in the walls, windows, and floors at building test sites. In addition, limited subjective tests were conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise. Representative peak levels of aircraft noise-induced building vibrations are reported and comparisons are made with structural damage criteria and with vibration levels induced by common domestic events. In addition, results of a pilot study are reported which indicate the human detection threshold for noise-induced floor vibrations.

  9. Surface instabilities and reorientation induced by vibration in microgravity conditions

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier; Ezquerro Navarro, Jose Miguel

    2012-07-01

    The behavior of vibrated fluids and, in particular, the surface or interfacial instabilities that commonly arise in these systems have been the subject of continued experimental and theoretical attention since Faraday's seminal experiments in 1831. Both orientation and frequency are critical in determining the response of the fluid to excitation. Low frequencies are associated with sloshing while higher frequencies may generate Faraday waves or cross-waves, depending on whether the axis of vibration is perpendicular or parallel to the interface. In addition, high frequency vibrations are known to produce large scale reorientation of the fluid (vibroequilibria), an effect that becomes especially pronounced in the absence of gravity. We describe the results of investigations conducted at the ESA affiliated Spanish User Support and Operations Centre (E-USOC) on the effect of vibrations on fluid interfaces, particularly the interaction between Faraday waves, which arise in vertically vibrated systems, cross-waves, which are found in horizontally forced systems, and large scale reorientation (vibroequilibria). Ongoing ground experiments utilizing a dual-axis shaker configuration are described, including the effect on pattern formation of varying the two independent forcing frequencies, amplitudes, and phases. Theoretical results, based on the analysis of reduced models, and on numerical simulations, are then described and compared to experiment. Finally, the interest of a corresponding microgravity experiment is discussed and implications for fluid management strategies considered.

  10. Field measurements and analyses of environmental vibrations induced by high-speed Maglev.

    Science.gov (United States)

    Li, Guo-Qiang; Wang, Zhi-Lu; Chen, Suwen; Xu, You-Lin

    2016-10-15

    Maglev, offers competitive journey-times compared to the railway and subway systems in markets for which distance between the stations is 100-1600km owing to its high acceleration and speed; however, such systems may have excessive vibration. Field measurements of Maglev train-induced vibrations were therefore performed on the world's first commercial Maglev line in Shanghai, China. Seven test sections along the line were selected according to the operating conditions, covering speeds from 150 to 430km/h. Acceleration responses of bridge pier and nearby ground were measured in three directions and analyzed in both the time and frequency domain. The effects of Maglev train speed on vibrations of the bridge pier and ground were studied in terms of their peak accelerations. Attenuation of ground vibration was investigated up to 30m from the track centerline. Effects of guideway configuration were also analyzed based on the measurements through two different test sections with same train speed of 300km/h. The results showed that peak accelerations exhibited a strong correlation with both train speed and distance off the track. Guideway configuration had a significant effect on transverse vibration, but a weak impact on vertical and longitudinal vibrations of both bridge pier and ground. Statistics indicated that, contrary to the commonly accepted theory and experience, vertical vibration is not always dominant: transverse and longitudinal vibrations should also be considered, particularly near turns in the track. Moreover, measurements of ground vibration induced by traditional high-speed railway train were carried out with the same testing devices in Bengbu in the Anhui Province. Results showed that the Maglev train generates significantly different vibration signatures as compared to the traditional high-speed train. The results obtained from this paper can provide good insights on the impact of Maglev system on the urban environment and the quality of human life

  11. Active Control of Panel Vibrations Induced by a Boundary Layer Flow

    Science.gov (United States)

    Chow, Pao-Liu

    1998-01-01

    In recent years, active and passive control of sound and vibration in aeroelastic structures have received a great deal of attention due to many potential applications to aerospace and other industries. There exists a great deal of research work done in this area. Recent advances in the control of sound and vibration can be found in the several conference proceedings. In this report we will summarize our research findings supported by the NASA grant NAG-1-1175. The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to study the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. The vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings will be presented in the next three sections. In Section II we shall describe our results on the boundary control of nonlinear panel vibration, with or without flow excitation. Section III is concerned with active control of the vibration and sound radiation from a nonlinear elastic panel. A detailed description of our work on the parametric vibrational control of nonlinear elastic panel will be presented in Section IV. This paper will be submitted to the Journal

  12. Effect of structural design on traffic-induced building vibrations

    DEFF Research Database (Denmark)

    Persson, Peter; Andersen, Lars Vabbersgaard; Persson, Kent

    2017-01-01

    are related to the type of construction material (if it would be a light or heavy structure), and to the slab thickness. The finite element method is employed for discretizing the building structure that is coupled to a semi-analytical model considering a layered ground. © 2017 The Authors. Published......Population growth and urbanization results in densified cities, where new buildings are being built closer to existing vibration sources such as road-, tram- and rail traffic. In addition, new transportation systems are constructed closer to existing buildings. Potential disturbing vibrations...... properties, and type and size of the building are governing factors. In the paper, a study is presented aiming at investigating the influence of various parameters of the building's structural design on vibration levels in the structure caused by ground surface loads, e.g. traffic. Parameters studied...

  13. Corrosion Product Film-Induced Stress Facilitates Stress Corrosion Cracking.

    Science.gov (United States)

    Wang, Wenwen; Zhang, Zhiliang; Ren, Xuechong; Guan, Yongjun; Su, Yanjing

    2015-06-11

    Finite element analyses were conducted to clarify the role of corrosion product films (CPFs) in stress corrosion cracking (SCC). Flat and U-shaped edge-notched specimens were investigated in terms of the CPF-induced stress in the metallic substrate and the stress in the CPF. For a U-shaped edge-notched specimen, the stress field in front of the notch tip is affected by the Young's modulus of the CPF and the CPF thickness and notch geometry. The CPF-induced tensile stress in the metallic substrate is superimposed on the applied load to increase the crack tip strain and facilitate localized plasticity deformation. In addition, the stress in the CPF surface contributes to the rupture of the CPFs. The results provide physical insights into the role of CPFs in SCC.

  14. Mechanisms of Stress-induced Visceral Pain

    OpenAIRE

    Greenwood-Van Meerveld, Beverley; Johnson, Anthony C

    2018-01-01

    Evidence suggests that long-term stress facilitates visceral pain through sensitization of pain pathways and promotes chronic visceral pain disorders such as the irritable bowel syndrome (IBS). This review will describe the importance of stress in exacerbating IBS-induced abdominal pain. Additionally, we will briefly review our understanding of the activation of the hypothalamic-pituitary-adrenal axis by both chronic adult stress and following early life stress in the pathogenesis of IBS. The...

  15. Stark-induced adiabatic Raman ladder for preparing highly vibrationally excited quantum states of molecular hydrogen

    Science.gov (United States)

    Mukherjee, Nandini; Perreault, William E.; Zare, Richard N.

    2017-07-01

    We present a multi-color ladder excitation scheme that exploits Stark-induced adiabatic Raman passage to selectively populate a highly excited vibrational level of a molecule. We suggest that this multi-color coherent ladder excitation provides a practical way of accessing levels near the vibrational dissociation limit as well as the dissociative continuum, which would allow the generation of an entangled pair of fragments with near-zero relative kinetic energy. Specifically, we consider four- and six-photon coherent excitation of molecular hydrogen to high vibrational levels via intermediate vibrational levels, which are pairwise coupled by two-photon resonant interaction. Using a sequence of three partially overlapping, single-mode, nanosecond laser pulses we show that the sixth vibrational level of H2, which is too weakly coupled to be easily accessed by direct two-photon Raman excitation from the ground vibrational level, can be efficiently populated without leaving any population stranded in the intermediate level. Furthermore, we show that the fourteenth vibrational level of H2, which is the highest vibrational level in the ground electronic state with a binding energy of 22 meV, can be efficiently and selectively populated using a sequence of four pulses. The present technique offers the unique possibility of preparing entangled quantum states of H atoms without resorting to an ultracold system.

  16. Incorporating a disturbance observer with direct velocity feedback for control of human-induced vibrations

    Science.gov (United States)

    Nyawako, Donald; Reynolds, Paul; Hudson, Emma

    2016-04-01

    Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.

  17. Research on wall shear stress considering wall roughness when shear swirling flow vibration cementing

    Science.gov (United States)

    Cui, Zhihua; Ai, Chi; Feng, Fuping

    2017-01-01

    When shear swirling flow vibration cementing, the casing is revolving periodically and eccentrically, which leads to the annulus fluid in turbulent swirling flow state. The wall shear stress is more than that in laminar flow field when conventional cementing. The paper mainly studied the wall shear stress distribution on the borehole wall when shear swirling flow vibration cementing based on the finite volume method. At the same time, the wall roughness affected and changed the turbulent flow near the borehole wall and the wall shear stress. Based on the wall function method, the paper established boundary conditions considering the wall roughness and derived the formula of the wall shear stress. The results showed that the wall roughness significantly increases the wall shear stress. However, the larger the wall roughness, the greater the thickness of mud cake, which weakening the cementing strength. Considering the effects in a comprehensive way, it is discovered that the particle size of solid phase in drilling fluid is about 0.1 mm to get better cementing quality.

  18. Self-excited vibration of the shell-liquid coupled system induced by dry friction

    Science.gov (United States)

    Xijun, Liu; Dajun, Wang; Yushu, Chen

    1995-11-01

    The nonlinear vibration theory and the experimental modal analysis are used in this paper to study the self-excited vibration of the shell-liquid coupled system induced by dry friction. The effect of dry friction stick-slip coefficients and rubbing velocity on self-excited vibration, and the limit cycle and Hopf bifurcation solution of the system are obtained. In particular, it is shown that the phenomenon of 4 point (or 6 point) water droplet spurting of the Chinese cultural relic Dragon Washbasin is the result of the perfect combination of the self-excited vibration induced by dry friction and its special modes, which indicates the significant scientific value of the Chinese cultural relic Dragon Washbasin.

  19. Vibrations of composite steel-concrete floors induced by human activities

    Directory of Open Access Journals (Sweden)

    Gluhović Nina

    2016-01-01

    Full Text Available The latest demands in construction design towards slender structures with large spans, large open interiors, unconventional shapes and constructional solutions are leading to the extensive problems related to the serviceability limit state. Slender structures with large spans have lower natural frequencies and lower natural damping, considerably influencing the dynamic response of the structure. Annoying vibrations induced by human activities can significantly affect the structure's functionality, comfort of people and quality of life. Design recommendations for composite steel-concrete floor vibrations can be found in different standards. This paper presents a short overview of design procedures for vibrations of composite steel-concrete beams and design recommendations of floor vibrations induced by human activities, through two design criteria.

  20. Some Transverse Resonant Vibration Characteristics of Wire Rope with Application to Flow-Induced Cable Vibrations

    Science.gov (United States)

    1974-12-10

    A cabhle in tOw second mode We will use the approach developed by Murthy and Ramakrishna 181 to determine tie stretching contril )ution for the...resonantly vibrating wire. From that paper, the damping quality factor, Q = 27/T , of the first four modes of a piano wire yields essentially the same value...when divided by the corresponding resonant frequency. Both the quality factor Q and the quotient Q/f 21/6f are listed in Table 3 for comparison

  1. Whole-body vibration and postural stress among operators of construction equipment: a literature review.

    Science.gov (United States)

    Kittusamy, N Kumar; Buchholz, Bryan

    2004-01-01

    Operators of construction equipment perform various duties at work that expose them to a variety of risk factors that may lead to health problems. A few of the health hazards among operators of construction equipment are: (a) whole-body vibration, (b) awkward postural requirements (including static sitting), (c) dust, (d) noise, (e) temperature extremes, and (f) shift work. It has been suggested that operating engineers (OEs) are exposed to two important risk factors for the development of musculoskeletal disorders: whole-body vibration and non-neutral body postures. This review evaluates selected papers that have studied exposure to whole-body vibration and awkward posture among operators of mobile equipment. There have been only few studies that have specifically examined exposure of these risk factors among operators of construction equipment. Thus other studies from related industry and equipment were reviewed as applicable. In order to better understand whole-body vibration and postural stress among OEs, it is recommended that future studies are needed in evaluating these risk factors among OEs.

  2. Train-induced ground vibrations : Modeling and experiments

    NARCIS (Netherlands)

    Ditzel, A.

    2003-01-01

    Ground vibrations generated by high-speed trains are of great concern because of the possible damage they can cause to buildings or other structures near the track, and the annoyance to the public living in the vicinity of the track. Particularly in soft-soil regions, where the wave speed is

  3. Effect of Building Characteristics on Vibration-Induced Acceleration ...

    African Journals Online (AJOL)

    The effective accelerations for non-structural components located at different heights in a building are amplified due to the vibrations of the building and the components themselves. The amplifications along the height of buildings having different heights, structural systems and stiffness were studied. Four, eight and sixteen ...

  4. The effect of fatigue on abnormal vibration induced illusion of movement in idiopathic focal dystonia.

    Science.gov (United States)

    Frima, N; Rome, S M; Grünewald, R A

    2003-08-01

    Perception of vibration induced illusionary movement (VIIM) is subnormal in dystonic patients, suggesting abnormal sensory-motor processing in patients with idiopathic focal dystonia. To examine the effects of fatigue on VIIM in patients with idiopathic torticollis. An illusionary sensation of arm extension was evoked by an 80 Hz transcutaneous vibratory stimulus applied to the biceps brachii tendon while the arm was restrained. Blindfolded patients attempted to copy the perceived movement of the vibrated arm with the opposite (tracking) arm and the change in elbow angle of the tracking arm was quantified over 45 seconds. The tasks were repeated following volitional fatigue of the vibrated arm. The subnormal perception of VIIM perceived by patients with torticollis, occurring bilaterally and remote from the location of dystonic symptoms, was corrected by fatigue of the vibrated arm compared with prefatigue values (mean (SEM): 19.04 degrees (1.76) degrees v 24.25 degrees (2.41 degrees ); p = 0.01, paired t test). While a combination of central or peripheral factors may be involved in the correction of abnormal perception of the vibration induced illusion of movement in dystonia, subnormal elasticity of muscle spindles could be implicated in the impaired perception of vibration induced illusionary movement and may predispose an individual towards developing idiopathic focal dystonia.

  5. A two scale modeling and computational framework for vibration-induced Raynaud syndrome.

    Science.gov (United States)

    Hua, Yue; Lemerle, Pierre; Ganghoffer, Jean-François

    2017-07-01

    Hand-Arm Vibration syndrome (HAVS), usually caused by long-term use of hand-held power tools, can in certain manifestations alter the peripheral blood circulation in the hand-arm region. HAVS typically occurs after exposure to cold, causing an abnormally strong vasoconstriction of blood vessels. A pathoanatomical mechanism suggests that a reduction of the lumen of the blood vessels in VWF (Vibration White Finger) subjects, due to either hypertrophy or thickening of the vessel wall, may be at the origin of the disease. However, the direct and indirect effects of the load of the hand-held tools on the structure of blood vessels remain controversial:.one hypothesis is the mechanical action of vibration on the local acral dysregulation and/or on the vessel histomorphological modifications. Another hypothesis is the participation of the sympathetic nervous system to this dysregulation. In this paper, we assume the modifications as mechanobiological growth and the load-effect relationship may be interpreted as directly or indirectly induced. This work is the first attempt to model the effect of vibration through soft tissues onto the distal capillaries, addressing the double paradigm of multi space-time scales, i.e. low period vibration versus high time constant of the growth phenomenon as well as vibrations propagating in the macroscopic tissue including the microscopic capillary structures subjected to a pathological microstructural evolution. The objective is to lay down the theoretical basis of growth modeling for the small distal artery, with the ability to predict the geometrical and structural changes of the arterial walls caused by vibration exposure. We adopt the key idea of splitting the problem into one global vibration problem at the macroscopic scale and one local growth problem at the micro level. The macroscopic hyperelastic viscous dynamic model of the fingertip cross-section is validated by fitting experimental data. It is then used in steady

  6. Estimation of Subjective Difficulty and Psychological Stress by Ambient Sensing of Desk Panel Vibrations

    Science.gov (United States)

    Hamaguchi, Nana; Yamamoto, Keiko; Iwai, Daisuke; Sato, Kosuke

    We investigate ambient sensing techniques that recognize writer's psychological states by measuring vibrations of handwriting on a desk panel using a piezoelectric contact sensor attached to its underside. In particular, we describe a technique for estimating the subjective difficulty of a question for a student as the ratio of the time duration of thinking to the total amount of time spent on the question. Through experiments, we confirm that our technique correctly recognizes whether or not a person writes something down on paper by measured vibration data at the accuracy of over 80 %, and that the order of computed subjective difficulties of three questions is coincident with that reported by the subject in 60 % of experiments. We also propose a technique to estimate a writer's psychological stress by using the standard deviation of the spectrum of the measured vibration. Results of a proof-of-concept experiment show that the proposed technique correctly estimates whether or not the subject feels stress at least 90 % of the time.

  7. Vibration Mitigation without Dissipative Devices: First Large-Scale Testing of a State Switched Inducer

    Directory of Open Access Journals (Sweden)

    Daniel Tirelli

    2014-01-01

    Full Text Available A new passive device for mitigating cable vibrations is proposed and its efficiency is assessed on 45-meter long taut cables through a series of free and forced vibration tests. It consists of a unilateral spring attached perpendicularly to the cable near the anchorage. Because of its ability to change the cable dynamic behaviour through intermittent activation, the device has been called state switched inducer (SSI. The cable behaviour is shown to be deeply modified by the SSI: the forced vibration response is anharmonicc and substantially reduced in amplitude whereas the free vibration decay is largely sped up through a beating phenomenon. The vibration mitigation effect is mainly due to the activation and coupling of various vibration modes, as evidenced in the response spectra of the equipped cable. This first large-scale experimental campaign shows that the SSI outperforms classical passive devices, thus paving the way to a new kind of low-cost vibration mitigation systems which do not rely on dissipation.

  8. Vortex-Induced Vibrations of a Riser with Design Variations

    Science.gov (United States)

    2016-06-19

    profile (x-z plane) reveals how the VIV amplitude changes along the river. Each of the two profiles consists of a series of snapshots every 0.01...stiffness in the z-direction, which in turn allows the amplitude of VIV to increase. In summary, this pendulation and any shape/tension changes are...for this is that as the pendulum vibrates up into a more horizontal orientation, stiffness decreases. This then allows the inter-cycle sub- amplitude

  9. Vortex-Induced Vibration Suppression of a Circular Cylinder with Vortex Generators

    Directory of Open Access Journals (Sweden)

    Shi-bo Tao

    2016-01-01

    Full Text Available The vortex-induced vibration is one of the most important factors to make the engineering failure in wind engineering. This paper focuses on the suppression method of vortex-induced vibration that occurs on a circular cylinder fitted with vortex generators, based on the wind tunnel experiment. The effect of the vortex generators is presented with comparisons including the bare cylinder. The experimental results reveal that the vortex generators can efficiently suppress vortex-induced vibration of the circular cylinder. Vortex generator control can make the boundary layer profile fuller and hence more resistant to separation. The selections of skew angles and the angular position have a significant influence on the vortex generator control effect. By correlation analysis, it can be concluded that the vortex generators can inhibit the communication between the two shear layers and produce streamwise vortices to generate a disturbance in the spanwise direction.

  10. Self-induced vibrations of a DU96-W-180 airfoil in stall

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Sørensen, Niels N.

    2014-01-01

    vibrations. The analysis showed significant differences between the aerodynamic stability limits predicted by 2D and 3D CFD computations. A general agreement was reached between the prescribed motion and elastically mounted airfoil computations. 3D computations indicated that vortex-induced vibrations......This work presents an analysis of two-dimensional (2D) and three-dimensional (3D) non-moving, prescribed motion and elastically mounted airfoil computational fluid dynamics (CFD) computations. The elastically mounted airfoil computations were performed by means of a 2D structural model with two...... degrees of freedom. The computations aimed at investigating the mechanisms of both vortex-induced and stall-induced vibrations related to a wind turbine blade at standstill conditions. In this work, a DU96-W-180 airfoil was used in the angle-of-attack region potentially corresponding to stallinduced...

  11. Stress-induced senescence and plant tolerance to abiotic stress.

    Science.gov (United States)

    Sade, Nir; Del Mar Rubio-Wilhelmi, María; Umnajkitikorn, Kamolchanok; Blumwald, Eduardo

    2017-07-26

    Senescence is an age-dependent process, ultimately leading to plant death, that in annual crop plants overlaps with the reproductive stage of development. Research on the molecular and biochemical mechanisms of leaf senescence has revealed a multi-layered regulatory network operating to control age-dependent processes. Abiotic stress-induced senescence challenges source-sink relationships and results in significant reduction in crop yields. Although processes associated with plant senescence are well studied, the mechanisms regulating stress-induced senescence are not well known. Here, we discuss the effects of abiotic stress on crop productivity, mechanisms associated with stress-induced senescence, and the possible use of these mechanisms for the generation of plant stress tolerance. We emphasize the involvement of source strength and stability of the photosynthetic apparatus in this process, and suggest a possible role of a perennial plant life strategy for the amelioration of stress-induced senescence. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  12. Coupling system dynamics and contact behaviour: Modelling bearings subjected to environmental induced vibrations and ‘false brinelling’ degradation

    Science.gov (United States)

    Massi, Francesco; Rocchi, J.; Culla, A.; Berthier, Y.

    2010-05-01

    During the last decades the increase in power of mechanical systems and the demand for increasing service life leads mechanical components of a system to work in extreme conditions. Moreover, actual mechanical systems include surfaces in sliding contact that are subjected to wear if exposed to high vibration. In fact, the vibration of components in contact results in large oscillations of the local contact stresses, due to the local deformation of the components at the contact interfaces. To approach correctly tribological problems, the coupling between the scale of the mechanism (system dynamics) and the scale of the contact needs to be accounted for. This paper presents an analysis concerning the influence of the vibrations induced by aircraft engines on the contact stresses of rolling bearings of the bleed system valves. To study the wear, resulting from false brinelling at the contact surfaces between balls and races of the bearings, it is then necessary to determine the forces due to the system vibrations and acting at the bearing connections with the structure. In order to perform a numerical transient analysis of the system dynamics a nonlinear simplified model of the valve (mechanism scale) is developed. The model is validated by comparing the numerical results with experimental tests. The time behaviour of the global forces on the bearings, and the respective displacements between the contact surfaces, are then used as inputs for a finite element model of the bearings (contact scale). The model is used to calculate and analyze the behaviour in time of the local contact constraints between race and balls. This analysis, developed in the framework of a European project, is an example of the proposed general approach to contact problems, by coupling the analysis of the mechanism and contact scales.

  13. Stress induced obesity: lessons from rodent models of stress.

    Science.gov (United States)

    Patterson, Zachary R; Abizaid, Alfonso

    2013-01-01

    Stress was once defined as the non-specific result of the body to any demand or challenge to homeostasis. A more current view of stress is the behavioral and physiological responses generated in the face of, or in anticipation of, a perceived threat. The stress response involves activation of the sympathetic nervous system and recruitment of the hypothalamic-pituitary-adrenal (HPA) axis. When an organism encounters a stressor (social, physical, etc.), these endogenous stress systems are stimulated in order to generate a fight-or-flight response, and manage the stressful situation. As such, an organism is forced to liberate energy resources in attempt to meet the energetic demands posed by the stressor. A change in the energy homeostatic balance is thus required to exploit an appropriate resource and deliver useable energy to the target muscles and tissues involved in the stress response. Acutely, this change in energy homeostasis and the liberation of energy is considered advantageous, as it is required for the survival of the organism. However, when an organism is subjected to a prolonged stressor, as is the case during chronic stress, a continuous irregularity in energy homeostasis is considered detrimental and may lead to the development of metabolic disturbances such as cardiovascular disease, type II diabetes mellitus and obesity. This concept has been studied extensively using animal models, and the neurobiological underpinnings of stress induced metabolic disorders are beginning to surface. However, different animal models of stress continue to produce divergent metabolic phenotypes wherein some animals become anorexic and lose body mass while others increase food intake and body mass and become vulnerable to the development of metabolic disturbances. It remains unclear exactly what factors associated with stress models can be used to predict the metabolic outcome of the organism. This review will explore a variety of rodent stress models and discuss the

  14. Numerical investigation on vibration and noise induced by unsteady flow in an axial-flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Eryun; Ma, Zui Ling; Yang, Ai Ling; Nan, Guo Fang [School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai (China); Zhao, Gai Ping [School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai (China); Li, Guo Ping [Shanghai Marine Equipment Research Institute, Shanghai (China)

    2016-12-15

    Full-scale structural vibration and noise induced by flow in an axial-flow pump was simulated by a hybrid numerical method. An unsteady flow field was solved by a large eddy simulation-based computational fluid dynamics commercial code, Fluent. An experimental validation on pressure fluctuations was performed to impose an appropriate vibration exciting source. The consistency between the computed results and experimental tests were interesting. The modes of the axial-flow pump were computed by the finite element method. After that, the pump vibration and sound field were solved using a coupled vibro-acoustic model. The numerical results indicated that the the blade-passing frequency was the dominant frequency of the vibration acceleration of the pump. This result was consistent with frequency spectral characteristics of unsteady pressure fluctuation. Finally, comparisons of the vibration acceleration between the computed results and the experimental test were conducted. These comparisons validated the computed results. This study shows that using the hybrid numerical method to evaluate the flow-induced vibration and noise generated in an axial-flow pump is feasible.

  15. Tactile perception of skin and skin cream by friction induced vibrations.

    Science.gov (United States)

    Ding, Shuyang; Bhushan, Bharat

    2016-11-01

    Skin cream smooths, softens, and moistens skin by altering surface roughness and tribological properties of skin. Sliding generates vibrations that activate mechanoreceptors located in skin. The brain interprets tactile information to identify skin feel. Understanding the tactile sensing mechanisms of skin with and without cream treatment is important to numerous applications including cosmetics, textiles, and robotics sensors. In this study, frequency spectra of friction force and friction induced vibration signals were carried out to investigate tactile perception by an artificial finger sliding on skin. The influence of normal load, velocity, and cream treatment time were studied. Coherence between friction force and vibration signals were found. The amplitude of vibration decreased after cream treatment, leading to smoother perception. Increasing normal load or velocity between contacting surfaces generated a smoother perception with cream treatment, but rougher perception without treatment. As cream treatment time increases, skin becomes smoother. The related mechanisms are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Vibrational resonance induced by transition of phase-locking modes in excitable systems.

    Science.gov (United States)

    Yang, Lijian; Liu, Wangheng; Yi, Ming; Wang, Canjun; Zhu, Qiaomu; Zhan, Xuan; Jia, Ya

    2012-07-01

    We study the occurrence of vibrational resonance as well as the underlying mechanism in excitable systems. The single vibration resonance and vibration bi-resonance are observed when tuning the amplitude and frequency of high-frequency force simultaneously. Furthermore, by virtue of the phase diagram of low-frequency-signal-free FitzHugh-Nagumo model, it is found that each maxima of response measure is located exactly at the transition boundary of phase patterns. Therefore, it is the transition between different phase-locking modes that induces vibrational resonance in the excitable systems. Finally, this mechanism is verified in the Hodgkin-Huxley neural model. Our results provide insights into the transmission of weak signals in nonlinear systems, which are valuable in engineering for potential applications.

  17. Toxicant-induced oxidative stress in cancer.

    Science.gov (United States)

    Upham, B L; Wagner, J G

    2001-11-01

    The article highlighted in this issue is "The Role of Oxidative Stress in Indium Phosphide-Induced Lung Carcinogenesis in Rats" by Barbara C. Gottschling, Robert R. Maronpot, James R. Hailey, Shyamal Peddada, Cindy R. Moomaw, James E. Klaunig, and Abraham Nyska (pp. 28-40). The article integrates a traditional pathologic study of toxicant-induced pulmonary carcinogenesis with an immunohistologic assessment of oxidative stress, thereby determining a potential mechanism of action of a toxicant, specifically indium phosphide.

  18. Cholinergic Modulation of Restraint Stress Induced Neurobehavioral ...

    African Journals Online (AJOL)

    The involvement of the cholinergic system in restraint stress induced neurobehavioral alterations was investigated in rodents using the hole board, elevated plus maze, the open field and the light and dark box tests. Restraint stress (3h) reduced significantly (p<0.05) the number of entries and time spent in the open arm, ...

  19. Measurement of ground and nearby building vibration and noise induced by trains in a metro depot.

    Science.gov (United States)

    Zou, Chao; Wang, Yimin; Wang, Peng; Guo, Jixing

    2015-12-01

    Metro depots are where subway trains are parked and where maintenance is carried out. They usually occupy the largest ground areas in metro projects. Due to land utilization problems, Chinese cities have begun to develop over-track buildings above metro depots for people's life and work. The frequently moving trains, when going into and out of metro depots, can cause excessive vibration and noise to over-track buildings and adversely affect the living quality of the building occupants. Considering the current need of reliable experimental data for the construction of metro depots, field measurements of vibration and noise on the ground and inside a nearby 3-story building subjected to moving subway trains were conducted in a metro depot at Guangzhou, China. The amplitudes and frequency contents of velocity levels were quantified and compared. The composite A-weighted equivalent sound levels and maximum sound levels were captured. The predicted models for vibration and noise of metro depot were proposed based on existing models and verified. It was found that the vertical vibrations were significantly greater than the horizontal vibrations on the ground and inside the building near the testing line. While at the throat area, the horizontal vibrations near the curved track were remarkably greater than the vertical vibrations. The attenuation of the vibrations with frequencies above 50 Hz was larger than the ones below 50 Hz, and the frequencies of vibration transmitting to adjacent buildings were mainly within 10-50 Hz. The largest equivalent sound level generated in the throat area was smaller than the testing line one, but the instantaneous maximum sound level induced by wheels squeal, contact between wheels and rail joints as well as turnout was close to or even greater than the testing line one. The predicted models gave a first estimation for design and assessment of newly built metro depots. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. An investigation of vibration-induced protein desorption mechanism using a micromachined membrane and PZT plate.

    Science.gov (United States)

    Yeh, Po Ying; Le, Yevgeniya; Kizhakkedathu, Jayachandran N; Chiao, Mu

    2008-10-01

    A micromachined vibrating membrane is used to remove adsorbed proteins on a surface. A lead zirconate titanate (PZT) composite (3 x 1 x 0.5 mm) is attached to a silicon membrane (2,000 x 500 x 3 microm) and vibrates in a flexural plate wave (FPW) mode with wavelength of 4,000/3 microm at a resonant frequency of 308 kHz. The surface charge on the membrane and fluid shear stress contribute in minimizing the protein adsorption on the SiO(2) surface. In vitro characterization shows that 57 +/- 10% of the adsorbed bovine serum albumin (BSA), 47 +/- 13% of the immunoglobulin G (IgG), and 55.3~59.2 +/- 8% of the proteins from blood plasma are effectively removed from the vibrating surface. A simulation study of the vibration-frequency spectrum and vibrating amplitude distribution matches well with the experimental data. Potentially, a microelectromechanical system (MEMS)-based vibrating membrane could be the tool to minimize biofouling of in vivo MEMS devices.

  1. STRESS INDUCED OBESITY: LESSONS FROM RODENT MODELS OF STRESS

    Directory of Open Access Journals (Sweden)

    Zachary Robert Patterson

    2013-07-01

    Full Text Available Stress is defined as the behavioral and physiological responses generated in the face of, or in anticipation of, a perceived threat. The stress response involves activation of the sympathetic nervous system and recruitment of the hypothalamic-pituitary-adrenal (HPA axis. When an organism encounters a stressor (social, physical, etc., these endogenous stress systems are stimulated in order to generate a fight-or-flight response, and manage the stressful situation. As such, an organism is forced to liberate energy resources in attempt to meet the energetic demands posed by the stressor. A change in the energy homeostatic balance is thus required to exploit an appropriate resource and deliver useable energy to the target muscles and tissues involved in the stress response. Acutely, this change in energy homeostasis and the liberation of energy is considered advantageous, as it is required for the survival of the organism. However, when an organism is subjected to a prolonged stressor, as is the case during chronic stress, a continuous irregularity in energy homeostasis is considered detrimental and may lead to the development of metabolic disturbances such as cardiovascular disease, type II diabetes mellitus and obesity. This concept has been studied extensively using animal models, and the neurobiological underpinnings of stress induced metabolic disorders are beginning to surface. However, different animal models of stress continue to produce divergent metabolic phenotypes wherein some animals become anorexic and loose body mass while others increase food intake and body mass and become vulnerable to the development of metabolic disturbances. It remains unclear exactly what factors associated with stress models can be used to predict the metabolic outcome of the organism. This review will explore a variety of rodent stress models and discuss the elements that influence the metabolic outcome in order to further our understanding of stress-induced

  2. Analytical Model of Rain-Wind Induced Vibration of High-Voltage Transmission Line

    Directory of Open Access Journals (Sweden)

    Chao Zhou

    2014-10-01

    Full Text Available Under rainfall conditions, rain-wind induced vibration occurs on high-voltage transmission line occasionally. This phenomenon is caused by raindrops hitting the high-voltage conductor with a certain velocity and suspends to the bottom surface of the high-voltage conductor. By action of wind velocity and high-voltage conductor's motion, some suspended raindrops will be blown away or shaken off. The remaining water may be reformed as upper rivulet and lower rivulet. Like the effect of icing galloping, this type of vibration can cause metal fatigue on fittings and towers, while its mechanism remains unknown. The objective of this paper is to validate an analytical model of rain-wind induced vibration of the high-voltage transmission line and to investigate the effect of wind velocity, rivulet motion, raindrop velocity, and time varying mass on the vibration amplitude. Taking Tuo-chang transmission line as an example, the analytical model is solved by Galerkin weighted residual method and central difference method. The numerical results are in agreement with the experimental data available in the literature. The analytical model enables more comprehensive understanding of the rain-wind induced vibration mechanism.

  3. Vortex-induced vibrations on a modern wind turbine blade

    DEFF Research Database (Denmark)

    Heinz, Joachim Christian; Sørensen, Niels N.; Zahle, Frederik

    2016-01-01

    . Aero-elastic computations of the elastic blade confirmed the findings of the frequency analysis. Inflow conditions with inclination angles between Ψ = 20° and Ψ = 55° and relatively low to moderate wind speeds between V = 16 and V = 26 m s-1 were sufficient to trigger severe edgewise blade vibrations......-body-based structural model of HAWC2 and the incompressible computational fluid dynamics solver EllipSys3D. The study utilizes detached eddy simulation computations and considers the three-dimensional blade geometry including blade twist and taper. A preliminary frequency analysis of the load variations on a stiff...

  4. Building vibrations induced by noise from rotorcraft and propeller aircraft flyovers

    Science.gov (United States)

    Shepherd, Kevin P.; Hubbard, Harvey H.

    1992-06-01

    Noise and building vibrations were measured for a series of helicopter and propeller-driven aircraft flyovers at WFF during May 1978. The building response data are compared with similar data acquired earlier at sites near Dulles and Kennedy Airports for operation of commercial jet transports, including the Concorde supersonic transport. Results show that noise-induced vibration levels in windows and walls are directly proportional to sound pressure level and that for a given noise level, the acceleration levels induced by a helicopter or a propeller-driven aircraft flyover cannot be distinguished from the acceleration levels induced by a commercial jet transport flyover. Noise-induced building acceleration levels were found to be lower than those levels which might be expected to cause structural damage and were also lower than some acceleration levels induced by such common domestic events as closing windows and doors.

  5. A distributed fiber vibration sensor utilizing dispersion induced walk-off effect in a unidirectional Mach-Zehnder interferometer.

    Science.gov (United States)

    Chen, Qingming; Jin, Chao; Bao, Yuan; Li, Zhaohui; Li, Jianping; Lu, Chao; Yang, Liang; Li, Guifang

    2014-02-10

    We propose and experimentally demonstrate a novel ultra-long range and sensitive distributed fiber vibration sensor. Only one unidirectional Mach-Zehnder interferometer (MZI) is employed in this scheme as the sensing element. In this sensor structure, we utilize chromatic dispersion-induced walk-off effect between the vibration signals sensed by two distributed feedback (DFB) lasers at different wavelengths to locate the vibration position. Vibration signals with frequencies up to 9 MHz can be detected and the spatial resolution of 31 m is achieved over 320 km of the standard single mode fiber. Monitoring multiple vibration sources can also be realized using this scheme.

  6. Vertical motion of particles in vibration-induced granular capillarity

    Directory of Open Access Journals (Sweden)

    Fan Fengxian

    2017-01-01

    Full Text Available When a narrow tube inserted into a static container filled with particles is subjected to vertical vibration, the particles rise in the tube, much resembling the ascending motion of a liquid column in a capillary tube. To gain insights on the particle dynamics dictating this phenomenon – which we term granular capillarity – we numerically investigate the system using the Discrete Element Method (DEM. We reproduce the dynamical process of the granular capillarity and analyze the vertical motion of the individual particles in the tube, as well as the average vertical velocities of the particles. Our simulations show that the height of the granular column fluctuates in a periodic or period-doubling manner as the tube vibrates, until a steady-state (capillary height is reached. Moreover, our results for the average vertical velocity of the particles in the tube at different radial positions suggest that granular convection is one major factor underlying the particle-based dynamics that lead to the granular capillarity phenomenon.

  7. Dissociative ionization of liquid water induced by vibrational overtone excitation

    Energy Technology Data Exchange (ETDEWEB)

    Natzle, W.C.

    1983-03-01

    Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

  8. Stochastic Response of Energy Balanced Model for Vortex-Induced Vibration

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Krenk, S.

    of lightly damped structures are found on two branches, with the highest amplification branch on the low-frequency branch. The effect free wind turbulence is to destabilize the vibrations on the high amplification branch, thereby reducing the oscillation amplitude. The effect is most pronounced for very......A double oscillator model for vortex-induced oscillations of structural elements based on exact power exchange between fluid and structure, recently proposed by authors, is extended to include the effect of the turbulent component of the wind. In non-turbulent flow vortex-induced vibrations...... lightly damped structures. The character of the structural vibrations changes with increasing turbulence and damping from nearly regular harmonic oscillation to typical narrow-banded stochastic response, closely resembling observed behaviour in experiments and full-scale structures....

  9. Reactive oxygen species regulatory mechanisms associated with rapid response of MC3T3-E1 cells for vibration stress

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ling; Gan, Xueqi; Zhu, Zhuoli; Yang, Yang; He, Yuting; Yu, Haiyang, E-mail: yhyang6812@scu.edu.cn

    2016-02-12

    Although many previous studies have shown that refractory period-dependent memory effect of vibration stress is anabolic for skeletal homeostasis, little is known about the rapid response of osteoblasts simply derived from vibration itself. In view of the potential role of reactive oxygen species (ROS) in mediating differentiated activity of osteoblasts, whether and how ROS regulates the rapid effect of vibration deserve to be demonstrated. Our findings indicated that MC3T3-E1 cells underwent decreased gene expression of Runx2, Col-I and ALP and impaired ALP activity accompanied by increased mitochondrial fission immediately after vibration loading. Moreover, we also revealed the involvement of ERK-Drp1 signal transduction in ROS regulatory mechanisms responsible for the rapid effect of vibration stress. - Highlights: • ROS contributed to the rapid response of MC3T3-E1 cells for vibration stress. • Imbalance of mitochondrial dynamics were linked to the LMHFV-derived rapid response. • The role of ERK-Drp1 signal pathway in the LMHFV-derived osteoblast rapid response.

  10. Investigation into the vibration of metro bogies induced by rail corrugation

    Science.gov (United States)

    Ling, Liang; Li, Wei; Foo, Elbert; Wu, Lei; Wen, Zefeng; Jin, Xuesong

    2017-01-01

    The current research of rail corrugation mainly focuses on the mechanisms of its formation and development. Compared with the root causes and development mechanisms, the wheel-rail impacts, the fatigue failure of vehicle-track parts, and the loss of ride comfort due to rail corrugation should also be taken into account. However, the influences of rail corrugation on vehicle and track vibration, and failure of vehicle and track structural parts are barely discussed in the literature. This paper presents an experimental and numerical investigation of the structural vibration of metro bogies caused by rail corrugation. Extensive experiments are conducted to investigate the effects of short-pitch rail corrugation on the vibration accelerations of metro bogies. A dynamic model of a metro vehicle coupled with a concrete track is established to study the influence of rail corrugation on the structural vibration of metro bogies. The field test results indicate that the short-pitch rail corrugation generates strong vibrations on the axle-boxes and the bogie frames, therefore, accelerates the fatigue failure of the bogie components. The numerical results show that short-pitch rail corrugation may largely reduce the fatigue life of the coil spring, and improving the damping value of the primary vertical dampers is likely to reduce the strong vibration induced by short-pitch rail corrugation. This research systematically studies the effect of rail corrugation on the vibration of metro bogies and proposes some remedies for mitigating strong vibrations of metro bogies and reducing the incidence of failure in primary coil springs, which would be helpful in developing new metro bogies and track maintenance procedures.

  11. Regarding "A new method for predicting nonlinear structural vibrations induced by ground impact loading" [Journal of Sound and Vibration, 331/9 (2012) 2129-2140

    Science.gov (United States)

    Cartmell, Matthew P.

    2016-09-01

    The Editor wishes to make the reader aware that the paper "A new method for predicting nonlinear structural vibrations induced by ground impact loading" by Jun Liu, Yu Zhang, Bin Yun, Journal of Sound and Vibration, 331 (2012) 2129-2140, did not contain a direct citation of the fundamental and original work in this field by Dr. Mark Svinkin. The Editor regrets that this omission was not noted at the time that the above paper was accepted and published.

  12. Effect of angle on flow-induced vibrations of pinniped vibrissae.

    Directory of Open Access Journals (Sweden)

    Christin T Murphy

    Full Text Available Two types of vibrissal surface structures, undulated and smooth, exist among pinnipeds. Most Phocidae have vibrissae with undulated surfaces, while Otariidae, Odobenidae, and a few phocid species possess vibrissae with smooth surfaces. Variations in cross-sectional profile and orientation of the vibrissae also exist between pinniped species. These factors may influence the way that the vibrissae behave when exposed to water flow. This study investigated the effect that vibrissal surface structure and orientation have on flow-induced vibrations of pinniped vibrissae. Laser vibrometry was used to record vibrations along the whisker shaft from the undulated vibrissae of harbor seals (Phoca vitulina and northern elephant seals (Mirounga angustirostris and the smooth vibrissae of California sea lions (Zalophus californianus. Vibrations along the whisker shaft were measured in a flume tank, at three orientations (0°, 45°, 90° to the water flow. The results show that vibration frequency and velocity ranges were similar for both undulated and smooth vibrissae. Angle of orientation, rather than surface structure, had the greatest effect on flow-induced vibrations. Vibration velocity was up to 60 times higher when the wide, flat aspect of the whisker faced into the flow (90°, compared to when the thin edge faced into the flow (0°. Vibration frequency was also dependent on angle of orientation. Peak frequencies were measured up to 270 Hz and were highest at the 0° orientation for all whiskers. Furthermore, CT scanning was used to quantify the three-dimensional structure of pinniped vibrissae that may influence flow interactions. The CT data provide evidence that all vibrissae are flattened in cross-section to some extent and that differences exist in the orientation of this profile with respect to the major curvature of the hair shaft. These data support the hypothesis that a compressed cross-sectional profile may play a key role in reducing self

  13. Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

    Science.gov (United States)

    Delor, Milan; Archer, Stuart A.; Keane, Theo; Meijer, Anthony J. H. M.; Sazanovich, Igor V.; Greetham, Gregory M.; Towrie, Michael; Weinstein, Julia A.

    2017-11-01

    Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer donor-bridge-acceptor-bridge-donor 'fork' system: asymmetric 13C isotopic labelling of one of the two -C≡C- bridges makes the two parallel and otherwise identical donor→acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UVpump(excitation)-IRpump(perturbation)-IRprobe(monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices.

  14. Concorde noise-induced building vibrations for Sully Plantation, Chantilly, Virginia

    Science.gov (United States)

    Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

    1976-01-01

    A study to assess the noise-induced building vibrations associated with Concorde operations is presented. The approach is to record the levels of induced vibrations and associated indoor/outdoor noise levels in selected homes, historic and other buildings near Dulles and Kennedy International Airports. Presented is a small, representative sample of data recorded at Sully Plantation, Chantilly, Virginia during the period of May 20 through May 28, 1976. Recorded data provide relationships between the vibration levels of walls, floors, windows, and the noise associated with Concorde operations (2 landings and 3 takeoffs), other aircraft, nonaircraft sources, and normal household activities. Results suggest that building vibrations resulting from aircraft operations were proportional to the overall sound pressure levels and relatively insensitive to spectral differences associated with the different types of aircraft. Furthermore, the maximum levels of vibratory response resulting from Concorde operations were higher than those associated with conventional aircraft. The vibrations of nonaircraft events were observed in some cases to exceed the levels resulting from aircraft operations. These nonaircraft events are currently being analyzed in greater detail.

  15. Pedestrian induced vertical vibrations: Response to running using the Response Spectrum Method

    DEFF Research Database (Denmark)

    Matteoni, Giulia; Georgakis, Christos

    2010-01-01

    Footbridges are increasingly prone to vibrations and designers are generally unable to predict pedestrian-induced vertical vibrations. Many aspects of human loading are infact not properly taken into account for in the load models employed by the international codes of practice, such as the rando...... into account variations in the structural characteristics, crowd morphology and return period. The correction factors, together with the reference acceleration, are used to determine the final response of the footbridge, for a given probability of load occurrence.......Footbridges are increasingly prone to vibrations and designers are generally unable to predict pedestrian-induced vertical vibrations. Many aspects of human loading are infact not properly taken into account for in the load models employed by the international codes of practice......, such as the randomness of crowds travelling across the footbridge. Moreover, the codes, for most of the part, do not deal with pedestrian loading other than walking, even though running and jumping can often produce larger loads and vibration amplitudes. In this paper, an investigation inot the response of footbridges...

  16. Numerical investigation of vortex shedding and vortex-induced vibration for flexible riser models

    Directory of Open Access Journals (Sweden)

    Zheng-Shou Chen

    2010-06-01

    Full Text Available The numerical study about the vortex-induced vibration and vortex shedding in the wake has been presented. Prior to the numerical simulation of flexible riser systems concerning engineering conditions, efficiency validating of the proposed FSI solution method have been performed. The comparison between numerical simulation and published experimental data shows that the CFD method designed for FSI solution could give acceptable result for the VIV prediction of flexible riser/pipe system. As meaningful study on VIV and vortex shedding mode with the focus on flexible riser model systems, two kinds of typical simulation cases have been carried out. One was related to the simulation of vortex visualization in the wake for a riser model subject to forced oscillation, and another was related to the simulation of fluid-structure interaction between the pipes of coupled multi-assembled riser system. The result from forced oscillation simulation shows that the vortex-induced vibration with high response frequency but small instantaneous vibration amplitude contributes to vortex conformation as much as the forced oscillation with large normalized amplitude does, when the frequency of forced oscillation was relatively high. In the multi-assembled riser systems, it has been found that the external current velocity and the distance between two pipes are the critical factors to determine the vibration state and the steady vibration state emerging in quad-pipe system may be destroyed more easily than dual-pipe system.

  17. Flow induced vibration of subsea gas production systems caused by choke valves

    NARCIS (Netherlands)

    Ligterink, N.E.; Groot, R. de; Gharaibah, E.; Slot, H.J.

    2012-01-01

    In the design of subsea flow systems the integrity and reliability is paramount. As the equipment must be designed to operate at a large variety of conditions, inherent to the many processes, evaluation of the integrity is complex. . Flow induced pulsations and vibrations can cause serious design

  18. Flow induced vibration of subsea gas production system caused by choke valves

    NARCIS (Netherlands)

    Ligterink, N.E.; Groot, R. de; Gharaibah, E.; Slot, H.J.

    2012-01-01

    In the design of subsea flow systems the integrity and reliability is paramount. As the equipment must be designed to operate at a large variety of conditions, inherent to the many processes, evaluation of the integrity is complex. . Flow induced pulsations and vibrations can cause serious design

  19. Two improvements on numerical simulation of 2-DOF vortex-induced vibration with low mass ratio

    Science.gov (United States)

    Kang, Zhuang; Ni, Wen-chi; Zhang, Xu; Sun, Li-ping

    2017-12-01

    Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vortex-induced vibration with low mass ratio, the accuracy is not satisfactory, especially for the maximum amplitudes. In Jauvtis and Williamson's work, the maximum amplitude of the cylinder with low mass ratio m*=2.6 can reach as large as 1.5 D to be called as the "super-upper branch", but from current literatures, few simulation results can achieve such value, even fail to capture the upper branch. Besides, it is found that the amplitude decays too fast in the lower branch with the RANS-based turbulence model. The reason is likely to be the defects of the turbulence model itself in the prediction of unsteady separated flows as well as the unreasonable setting of the numerical simulation parameters. Aiming at above issues, a modified turbulence model is proposed in this paper, and the effect of the acceleration of flow field on the response of vortex-induced vibration is studied based on OpenFOAM. By analyzing the responses of amplitude, phase and trajectory, frequency and vortex mode, it is proved that the vortex-induced vibration can be predicted accurately with the modified turbulence model under appropriate flow field acceleration.

  20. Laser-induced photochemical gas-phase reactions of vibrationally excited triplet molecules

    Science.gov (United States)

    Zalesskaya, G. A.; Yakovlev, D. L.; Sambor, E. G.

    2002-05-01

    Mechanisms and rates of laser-induced gas-phase reactions of vibrationally excited triplet ketones were studied after adding electron and hydrogen donors using time-resolved delayed fluorescence. The influence of various bimolecular competing processes on DF quenching was analyzed.

  1. Numerical Study of Structural Vibration Induced by Combustion Noise - One Way Interaction

    NARCIS (Netherlands)

    Pozarlik, Artur Krzysztof; Kok, Jacobus B.W.

    2007-01-01

    The turbulent flame in the lean combustion regime in a gas turbine combustor generates significant thermo-acoustic noise. The thermo-acoustic noise induces liner vibrations that may lead to fatigue damage of the combustion system. This phenomenon is investigated in the project FLUISTCOM using both

  2. Vibration-induced displacement using high-frequency resonators and friction layers

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    1998-01-01

    A mathematical model is set up to quantify vibration-induced motions of a slider with an imbedded resonator. A simple approximate expression is presented for predicting average velocities of the slider, agreeing fairly well with numerical integration of the full equations of motion. The simple ex...

  3. Nonlinear Vibrational Analysis of Nanobeams Embedded in an Elastic Medium including Surface Stress Effects

    Directory of Open Access Journals (Sweden)

    S. Azizi

    2015-01-01

    Full Text Available Due to size-dependent behavior of nanostructures, the classical continuum models are not applicable for the analyses at this submicron size. Surface stress effect is one of the most important matters which make the nanoscale structures have different properties compared to the conventional structures due to high surface to volume ratio. In the present study, nonlinear free vibrational characteristics of embedded nanobeams are investigated including surface stress effects. To this end, a thin surface layer is assumed on the upper and lower surfaces of the cross section to separate the surface and bulk of nanobeams with their own different material properties. Based on harmonic balance method, closed-form analytical solution is conducted for nonlinear vibrations to obtain natural frequencies of embedded nanobeams with and without considerations of surface elasticity and residual surface tension effects corresponding to the various values of nondimensional amplitude, elastic foundation modulus, and geometrical variables of the system. Selected numerical results are given to indicate the influence of each one in detail.

  4. PREFACE: 7th International Conference on Modern Practice in Stress and Vibration Analysis

    Science.gov (United States)

    Dulieu-Barton, J. M.

    2009-07-01

    The proceedings contain the papers presented at the 7th International Conference on Modern Practice in Stress and Vibration Analysis. The collection of papers represents the range of activities that are carried out to understand the functionality of engineering systems and structures through stress/strain based evaluation and dynamic response. The scope is broad and covers theoretical studies, modelling and experimental evaluations. Many of the papers cover integration techniques and approaches to better understanding of system performance and failure. All of the papers have been peer reviewed by at least two experts and represent the state of the art of research in this area. The conference is the seventh in the series, following on from previous conferences in Bath, Glasgow, Nottingham, Dublin, Sheffield and Liverpool. Although based in the British Isles the conference has a truly international flavour with offerings from 22 countries. The conference is organised by the Institute of Physics Applied Mechanics Group (formerly the Stress and Vibration Group). It incorporates activities associated with the British Society for Strain Measurement including the Measurements Lecture, the EMex Exhibition and the Young Stress Analyst Competition. The organising committee is grateful for the support of all of the authors, the scientific committee and keynote speakers who played a significant role in the review process, to John Edwards who was instrumental in managing the paper review and submission process, Dawn Stewart and Claire Garland of the Institute of Physics for organising the conference, social programme and registration and Biana Gale of the British Society for Strain Measurement for organising the Exhibition. The organising committee is also grateful to the sponsors of the conference for their kind support and to the co-sponsors for distributing information on the conference. Professor Janice M Dulieu-Barton Professor of Experimental Mechanics University of

  5. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  6. Gravity-induced stresses in finite slopes

    Science.gov (United States)

    Savage, W.Z.

    1994-01-01

    An exact solution for gravity-induced stresses in finite elastic slopes is presented. This solution, which is applied for gravity-induced stresses in 15, 30, 45 and 90?? finite slopes, has application in pit-slope design, compares favorably with published finite element results for this problem and satisfies the conditions that shear and normal stresses vanish on the ground surface. The solution predicts that horizontal stresses are compressive along the top of the slopes (zero in the case of the 90?? slope) and tensile away from the bottom of the slopes, effects which are caused by downward movement and near-surface horizontal extension in front of the slope in response to gravity loading caused by the additional material associated with the finite slope. ?? 1994.

  7. Magnetically induced rotor vibration in dual-stator permanent magnet motors

    Science.gov (United States)

    Xie, Bang; Wang, Shiyu; Wang, Yaoyao; Zhao, Zhifu; Xiu, Jie

    2015-07-01

    Magnetically induced vibration is a major concern in permanent magnet (PM) motors, which is especially true for dual-stator motors. This work develops a two-dimensional model of the rotor by using energy method, and employs this model to examine the rigid- and elastic-body vibrations induced by the inner stator tooth passage force and that by the outer. The analytical results imply that there exist three typical vibration modes. Their presence or absence depends on the combination of magnet/slot, force's frequency and amplitude, the relative position between two stators, and other structural parameters. The combination and relative position affect these modes via altering the force phase. The predicted results are verified by magnetic force wave analysis by finite element method (FEM) and comparison with the existing results. Potential directions are also given with the anticipation of bringing forth more interesting and useful findings. As an engineering application, the magnetically induced vibration can be first reduced via the combination and then a suitable relative position.

  8. Diabetic Cardiovascular Disease Induced by Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Yosuke Kayama

    2015-10-01

    Full Text Available Cardiovascular disease (CVD is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM. DM can lead to multiple cardiovascular complications, including coronary artery disease (CAD, cardiac hypertrophy, and heart failure (HF. HF represents one of the most common causes of death in patients with DM and results from DM-induced CAD and diabetic cardiomyopathy. Oxidative stress is closely associated with the pathogenesis of DM and results from overproduction of reactive oxygen species (ROS. ROS overproduction is associated with hyperglycemia and metabolic disorders, such as impaired antioxidant function in conjunction with impaired antioxidant activity. Long-term exposure to oxidative stress in DM induces chronic inflammation and fibrosis in a range of tissues, leading to formation and progression of disease states in these tissues. Indeed, markers for oxidative stress are overexpressed in patients with DM, suggesting that increased ROS may be primarily responsible for the development of diabetic complications. Therefore, an understanding of the pathophysiological mechanisms mediated by oxidative stress is crucial to the prevention and treatment of diabetes-induced CVD. The current review focuses on the relationship between diabetes-induced CVD and oxidative stress, while highlighting the latest insights into this relationship from findings on diabetic heart and vascular disease.

  9. Cell death induced by endoplasmic reticulum stress.

    Science.gov (United States)

    Iurlaro, Raffaella; Muñoz-Pinedo, Cristina

    2016-07-01

    The endoplasmic reticulum is an organelle with multiple functions. The synthesis of transmembrane proteins and proteins that are to be secreted occurs in this organelle. Many conditions that impose stress on cells, including hypoxia, starvation, infections and changes in secretory needs, challenge the folding capacity of the cell and promote endoplasmic reticulum stress. The cellular response involves the activation of sensors that transduce signaling cascades with the aim of restoring homeostasis. This is known as the unfolded protein response, which also intersects with the integrated stress response that reduces protein synthesis through inactivation of the initiation factor eIF2α. Central to the unfolded protein response are the sensors PERK, IRE1 and ATF6, as well as other signaling nodes such as c-Jun N-terminal kinase 1 (JNK) and the downstream transcription factors XBP1, ATF4 and CHOP. These proteins aim to restore homeostasis, but they can also induce cell death, which has been shown to occur by necroptosis and, more commonly, through the regulation of Bcl-2 family proteins (Bim, Noxa and Puma) that leads to mitochondrial apoptosis. In addition, endoplasmic reticulum stress and proteotoxic stress have been shown to induce TRAIL receptors and activation of caspase-8. Endoplasmic reticulum stress is a common feature in the pathology of numerous diseases because it plays a role in neurodegeneration, stroke, cancer, metabolic diseases and inflammation. Understanding how cells react to endoplasmic reticulum stress can accelerate discovery of drugs against these diseases. © 2015 FEBS.

  10. Concorde noise-induced building vibrations: International Airport Dulles. [studies by Langley Research Center

    Science.gov (United States)

    Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Finley, T. D.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

    1977-01-01

    A series of studies were conducted to assess the noise-induced building vibrations associated with Concorde operations. The vibration levels of windows, walls, and floors were measured along with the associated noise levels of Concorde, subsonic aircraft and some nonaircraft events. Test sites included Sully Plantation which is adjacent to Dulles International Airport and three residential homes located in Montgomery County, Maryland. The measured vibration response levels due to Concorde operations were found to be: (1) higher than the levels due to other aircraft, (2) less than the levels due to certain household events which involve direct impulsive loading such as door and window closing, (3) less than criteria levels for building damage, and (4) comparable to levels which are perceptible to people.

  11. Fatigue behavior of flexhoses and bellows due to flow-induced vibrations

    Science.gov (United States)

    Desai, P. V.; Thornhill, L.

    1986-01-01

    The analysis and results developed in a fresh approach to calculate flow induced vibration response of a flexible flow passage are summarized. The vibration results are further examined in the frequency domain to obtain dominant frequency information. A cumulative damage analysis due to cyclic strains is performed to obtain the number of cycles to failure for a metallic bellows of particular specifications under a variety of operational conditions. Sample plots of time and frequency domain responses are included. The complex listing of a computer program is provided. The program successively executes each of the analyses needed to calculate the vibration response, the frequency response, the cyclic strains and the number of cycles to failure. The program prompts the user for necessary input information. Sample data from the program is provided. The fatigue life results obtained by the computer model lie within an acceptable range of previously measured available data.

  12. Induced vibrations increase performance of a winged self-righting robot

    Science.gov (United States)

    Othayoth, Ratan; Xuan, Qihan; Li, Chen

    When upside down, cockroaches can open their wings to dynamically self-right. In this process, an animal often has to perform multiple unsuccessful maneuvers to eventually right, and often flails its legs. Here, we developed a cockroach-inspired winged self-righting robot capable of controlled body vibrations to test the hypothesis that vibrations assist self-righting transitions. Robot body vibrations were induced by an oscillating mass (10% of body mass) and varied by changing oscillation frequency. We discovered that, as the robot's body vibrations increased, righting probability increased, and righting time decreased (P <0.0001, ANOVA), confirming our hypothesis. To begin to understand the underlying physics, we developed a locomotion energy landscape model. Our model revealed that the kinetic energy fluctuations due to vibrations were comparable to the potential energy barriers required to transition from a metastable overturned orientation to an upright orientation. Our study supports the plausibility of locomotion energy landscapes for understanding locomotor transitions, but highlights the need for further stochastic modeling to capture the uncertain nature of when righting maneuvers result in successful righting.

  13. FIVPET Flow-Induced Vibration Test Report (1) - Candidate Spacer Grid Type I (Optimized H Type)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hee; Kang, Heung Seok; Yoon, Kyung Ho; Song, Kee Nam; Kim, Jae Yong

    2006-03-15

    The flow-induced vibration (FIV) test using a 5x5 partial fuel assembly was performed to evaluate mechanical/structural performance of the candidate spacer grid type I (Optimized H shape). From the measured vibration response of the test bundle and the flow parameters, design features of the spacer strap can be analyzed in the point of vibration and hydraulic aspect, and also compared with other spacer strap in simple comparative manner. Furthermore, the FIV test will contributes to understand behaviors of nuclear fuel in operating reactor. The FIV test results will be used to verify the theoretical model of fuel rod and assembly vibration. The aim of this report is to present the results of the FIV test of partial fuel assembly and to introduce the detailed test methodology and analysis procedure. In chapter 2, the overall configuration of test bundle and instrumented tube is remarked and chapter 3 will introduce the test facility (FIVPET) and test section. Chapter 4 deals with overall test condition and procedure, measurement and data acquisition devices, instrumentation equipment and calibration, and error analysis. Finally, test result of vibration and pressure fluctuation is presented and discussed in chapter 5.

  14. The efficacy of airflow and seat vibration on reducing visually induced motion sickness.

    Science.gov (United States)

    D'Amour, Sarah; Bos, Jelte E; Keshavarz, Behrang

    2017-09-01

    Visually induced motion sickness (VIMS) is a well-known sensation in virtual environments and simulators, typically characterized by a variety of symptoms such as pallor, sweating, dizziness, fatigue, and/or nausea. Numerous methods to reduce VIMS have been previously introduced; however, a reliable countermeasure is still missing. In the present study, the effect of airflow and seat vibration to alleviate VIMS was investigated. Eighty-two participants were randomly assigned to one of four groups (airflow, vibration, combined airflow and vibration, and control) and then exposed to a 15 min long video of a bicycle ride shot from first-person view. VIMS was measured using the Fast Motion Sickness Scale (FMS) and the Simulator Sickness Questionnaire (SSQ). Results showed that the exposure of airflow significantly reduced VIMS, whereas the presence of seat vibration, in contrast, did not have an impact on VIMS. Additionally, we found that females reported higher FMS scores than males, however, this sex difference was not found in the SSQ scores. Our findings demonstrate that airflow can be an effective and easy-to-apply technique to reduce VIMS in virtual environments and simulators, while vibration applied to the seat is not a successful method.

  15. Importance of Added Mass and Damping in Flow-Induced Vibration Analysis of Tubes Bundle: An Overview

    Directory of Open Access Journals (Sweden)

    Faisal Karim Shami

    2012-01-01

    Full Text Available Flow-induced vibration is of prime concern to the designers of heat exchangers subjected to high flows of gases or liquids. Excessive vibration may cause tube failure due to fatigue or fretting-wear. Tube failure results in, expensive plant upholding and suffers loss of production. Therefore, tube failure due to unwarranted vibration must be avoided in process heat exchangers and nuclear steam generators, preferably at design stage. Such vibration problems may be avoided through a comprehensive flowinduced vibration analysis before fabrication of heat exchangers. However, it requires an understanding of vibration mechanism and parameters related to flow-induced vibration. For an accurate vibration analysis, it is of prime importance to have good estimates of structural and flow related dynamic parameters. Thus dynamic parameters such as added mass and damping are of significant concern in a flow regime. The purpose of this paper is to provide an overview of our state of knowledge and role of dynamic parameters in flow-induced vibration on tube bundles due to current trend of larger heat exchangers. The present paper provides published data, analysis, evaluation, formulation, and experimental studies related to hydrodynamic mass and damping by a large number of researchers. Guidelines for experimental research and heat exchangers design related to added mass and damping mechanisms subjected to both single and two-phase flow are outlined in this paper.

  16. STUDY ON DE-NOISING METHODS FOR SOIL COMPRESSIVE STRESS SIGNAL DURING VIBRATION COMPACTION

    Directory of Open Access Journals (Sweden)

    Qingzhe Zhang

    2017-12-01

    Full Text Available The compressive stress signal of soil during vibration compaction is an unstable and transient saltation signal accompanied by broadband noise, and the spectra of the signal and noise always overlap. To extract the ideal original signal from noisy data, this paper studies several signal de-noising methods such as low-pass filtering, multi-resolution wavelet transform, spectrum subtraction and independent component analysis. Experiments show that the traditional low-pass filter is only applicable when the spectra of the signal and noise can be separated in the frequency domain. The multi-resolution wavelet transform can decompose the signal into different frequency bands and remove the noise efficiently by extracting useful the frequency band of the signal, but this method is not reliable when the signal to noise ratio (SNR is low. Spectrum subtraction can remove strong background noise with stationary statistical characteristics even if the noise level is high and the spectrum of the signal overlaps with that of the noise. Independent component analysis can extract weak signals which are combined with heavy noise and can separate the noise from signal effectively when the independent channel hypothesis holds. These de-noising methods are of great importance for further analysing vibration signals in engineering.

  17. Concorde noise-induced building vibrations, Sully Plantation - Report no. 2, Chantilly, Virginia

    Science.gov (United States)

    1976-01-01

    Noise-induced building vibrations associated with Concorde operations were studied. The approach is to record the levels of induced vibrations and associated indoor/outdoor noise levels in selected homes, historic and other buildings near Dulles International Airport. Representative data are presented which were recorded at Sully Plantation, Chantilly, Virginia during the periods of May 20 through May 28, 1976, and June 14 through June 17, 1976. Recorded data provide relationships between the vibration levels of windows, walls, floors, and the noise associated with Concorde operations, other aircraft, and nonaircraft events. The results presented are drawn from the combined May-June data base which is considerably larger than the May data base covered. The levels of window, wall and floor vibratory response resulting from Concorde operations are higher than the vibratory levels associated with conventional aircraft. Furthermore, the vibratory responses of the windows are considerably higher than those of the walls and floors. The window response is higher for aircraft than recorded nonaircraft events and exhibits a linear response relationship with the overall sound pressure level. For a given sound pressure level, the Concorde may cause more vibration than a conventional aircraft due to spectral or other differences. However, the responses associated with Concorde appear to be much more dependent upon sound pressure level than spectral or other characteristics of the noise.

  18. Using Fast Vibrations to Quench Friction-induced Oscillations

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    1999-01-01

    This work examines how friction-induced self-excited oscillations are affected by high-frequency ex-ternal excitation. Simple analytical approximations are derived for predicting the occurence of self-excited oscillations for the traditional mass-on-moving-belt model – with and without high-frequ...

  19. Suppression of wind-induced vibrations of a seesaw-type oscillator by means of a dynamic absorber

    NARCIS (Netherlands)

    Lumbantobing, H.

    2003-01-01

    In this paper the suppression of wind-induced vibrations of a seesaw-type oscillator by means of a dynamic absorber is considered. With suppression the shift of the critical flow velocity to higher values as well as the reduction of vibration amplitudes is meant. The equations of motion are derived

  20. Free vibration analysis of pre-stressed FGM Timoshenko beams under large transverse deflection by a variational method

    OpenAIRE

    Paul, Amlan; Das, Debabrata

    2017-01-01

    A theoretical study on free vibration behavior of pre-stressed functionally graded material (FGM) beam is carried out. Power law variation of volume fraction along the thickness direction is considered. Geometric non-linearity is incorporated through von Kármán non-linear strain–displacement relationship. The governing equation for the static problem is obtained using minimum potential energy principle. The dynamic problem for the pre-stressed beam is formulated as an eigenvalue problem using...

  1. Fatigue-induced changes in tonic vibration response (TVR) in humans: relationships between electromyographic and biochemical events.

    Science.gov (United States)

    Brerro-Saby, Christelle; Delliaux, Stéphane; Steinberg, Jean Guillaume; Jammes, Yves

    2008-11-01

    Fatigue-induced changes in the proprioceptive reflex loop were explored in humans by using the tonic electromyographic (EMG) response to vibration (TVR) and relating it to lactic acidosis (LA) and oxidative stress. TVR was measured in flexor digitorum superficialis before and after sustained or intermittent handgrip at maximal voluntary contraction (MVC). TVR variations were compared with the changes in EMG power spectrum preceding contractile fatigue, the Hoffman reflex (H-reflex), and plasma concentrations of LA and thiobarbituric acid reactive substances (TBARS). After both sustained and intermittent handgrips, TVR amplitude first declined then increased, independently from the changes in EMG power spectrum and H-reflex. TVR depression and facilitation were respectively concomitant with increases in LA and TBARS. The TVR depression was proportional to the increased LA level. The origin of TVR changes after muscle fatigue is questioned because the relationship between TVR depression and LA accumulation might be temporal, not causal, and changes in muscle stiffness were not explored.

  2. Noise-induced hearing loss and combined noise and vibration exposure.

    Science.gov (United States)

    Turcot, A; Girard, S A; Courteau, M; Baril, J; Larocque, R

    2015-04-01

    While there is a wide body of literature addressing noise-induced hearing loss (NIHL) and hand-arm vibration syndrome (HAVS) independently, relatively few studies have considered the combined effects of noise and vibration. These studies have suggested an increased risk of NIHL in workers with vibration white finger (VWF), though the relationship remains poorly understood. To determine whether hearing impairment is worse in noise-exposed workers with VWF than in workers with similar noise exposures but without VWF. The Quebec National Institute of Public Health audiometric database was used in conjunction with work-related accident and occupational diseases data from the Quebec workers' compensation board to analyse differences in audiometry results between vibration-exposed workers in the mining and forestry industries and the overall source population, and between mining and forestry workers with documented VWF and those without VWF. The International Organization for Standardization (ISO) 7029 standards were used to calculate hearing loss not attributable to age. 15751 vibration-exposed workers were identified in an overall source population of 59339. Workers with VWF (n = 96) had significantly worse hearing at every frequency studied (500, 1000, 2000 4000 Hz) compared with other mining and forestry workers without VWF. This study confirms previous findings of greater hearing loss at higher frequencies in workers with VWF, but also found a significant difference in hearing loss at low frequencies. It therefore supports the association between combined noise and hand-arm vibration (HAV) exposure and NIHL. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Study of flow induce vibration inside 3.5 inch hard disk drives

    Directory of Open Access Journals (Sweden)

    Wichitpon Seepangmon

    2014-06-01

    Full Text Available This study focused on flow induced vibration of head stack assembly (HSA in a 3.5 inch hard disk drive with 5 disks and 10 read/write heads. We studied the effects of air flow on gimbal flex and resonance on arm. The comparison of vibrations on slider between the normal model and the experiment has been done for verifying the model. The peaks of frequency in experiment match the normal model at 1,040 1,320 and 1,400 Hz respectively. After that, the RNG K-ε turbulence model was used to determine the turbulent air flow of 7,200 rpm hard disk drive. The comparison between the normal model and the model with spoiler was investigated by using, computational fluid dynamics software (ANSYS and FLUENT. The results shown velocity magnitudes at the arm were decreased by 0.725 - 57.689 % and pressure dropped by 74.028 - 87.222 %. The velocity magnitudes at the gimbal flex were decreased by 5.522 - 14.291 % and pressure dropped by 48.440 - 82.947 %. The peak of vibrations on arm and gimbal flex was occurred at the frequency 1200 Hz. The model with spoiler could reduce vibration at arm by 2.56 - 95.601 % and reduce vibration at gimbal flex by 4.065 - 95.503 %. In the conclusion, the model with a spoiler could decrease the vibration at all surface of the arm and gimbal flex due to the velocity and pressure reduction[1][4].

  4. Whole-body vibration induces distinct reflex patterns in human soleus muscle.

    Science.gov (United States)

    Karacan, Ilhan; Cidem, Muharrem; Cidem, Mehmet; Türker, Kemal S

    2017-06-01

    The neuronal mechanisms underlying whole body vibration (WBV)-induced muscular reflex (WBV-IMR) are not well understood. To define a possible pathway for WBV-IMR, this study investigated the effects of WBV amplitude on WBV-IMR latency by surface electromyography analysis of the soleus muscle in human adult volunteers. The tendon (T) reflex was also induced to evaluate the level of presynaptic Ia inhibition during WBV. WBV-IMR latency was shorter when induced by low- as compared to medium- or high-amplitude WBV (33.9±5.3msvs. 43.8±3.6 and 44.1±4.2ms, respectively). There was no difference in latencies between T-reflex elicited before WBV (33.8±2.4ms) and WBV-IMR induced by low-amplitude WBV. Presynaptic Ia inhibition was absent during low-amplitude WBV but was present during medium- and high-amplitude WBV. Consequently, WBV induces short- or long-latency reflexes depending on the vibration amplitude. During low-amplitude WBV, muscle spindle activation may induce the short- but not the long-latency WBV-IMR. Furthermore, unlike the higher amplitude WBV, low-amplitude WBV does not induce presynaptic inhibition at the Ia synaptic terminals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Long-term daily vibration exposure alters current perception threshold (CPT) sensitivity and myelinated axons in a rat-tail model of vibration-induced injury.

    Science.gov (United States)

    Krajnak, Kristine; Raju, Sandya G; Miller, G Roger; Johnson, Claud; Waugh, Stacey; Kashon, Michael L; Riley, Danny A

    2016-01-01

    Repeated exposure to hand-transmitted vibration through the use of powered hand tools may result in pain and progressive reductions in tactile sensitivity. The goal of the present study was to use an established animal model of vibration-induced injury to characterize changes in sensory nerve function and cellular mechanisms associated with these alterations. Sensory nerve function was assessed weekly using the current perception threshold test and tail-flick analgesia test in male Sprague-Dawley rats exposed to 28 d of tail vibration. After 28 d of exposure, Aβ fiber sensitivity was reduced. This reduction in sensitivity was partly attributed to structural disruption of myelin. In addition, the decrease in sensitivity was also associated with a reduction in myelin basic protein and 2',3'- cyclic nucleotide phosphodiasterase (CNPase) staining in tail nerves, and an increase in circulating calcitonin gene-related peptide (CGRP) concentrations. Changes in Aβ fiber sensitivity and CGRP concentrations may serve as early markers of vibration-induced injury in peripheral nerves. It is conceivable that these markers may be utilized to monitor sensorineural alterations in workers exposed to vibration to potentially prevent additional injury.

  6. CFD simulation of flow-induced vibration of an elastically supported airfoil

    OpenAIRE

    Šidlof Petr

    2016-01-01

    Flow-induced vibration of lifting or control surfaces in aircraft may lead to catastrophic consequences. Under certain circumstances, the interaction between the airflow and the elastic structure may lead to instability with energy transferred from the airflow to the structure and with exponentially increasing amplitudes of the structure. In the current work, a CFD simulation of an elastically supported NACA0015 airfoil with two degrees of freedom (pitch and plunge) coupled with 2D incompress...

  7. On vortex shedding and prediction of vortex-induced vibrations of circular cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Halse, Karl Henning

    1997-12-31

    In offshore installations, many crucial components can be classified as slender marine structures: risers, mooring lines, umbilicals and cables, pipelines. This thesis studies the vortex shedding phenomenon and the problem of predicting vortex-induced vibrations of such structures. As the development of hydrocarbons move to deeper waters, the importance of accurately predicting the vortex-induced response has increased and so the need for proper response prediction methods is large. This work presents an extensive review of existing research publications about vortex shedding from circular cylinders and the vortex-induced vibrations of cylinders and the different numerical approaches to modelling the fluid flow. The response predictions from different methods are found to disagree, both in response shapes and in vibration amplitudes. This work presents a prediction method that uses a fully three-dimensional structural finite element model integrated with a laminar two-dimensional Navier-Stokes solution modelling the fluid flow. This solution is used to study the flow both around a fixed cylinder and in a flexibly mounted one-degree-of-freedom system. It is found that the vortex-shedding process (in the low Reynolds number regime) is well described by the computer program, and that the vortex-induced vibration of the flexibly mounted section do reflect the typical dynamic characteristics of lock-in oscillations. However, the exact behaviour of the experimental results found in the literature was not reproduced. The response of the three-dimensional structural model is larger than the expected difference between a mode shape and a flexibly mounted section. This is due to the use of independent hydrodynamic sections along the cylinder. The predicted response is not unrealistic, and the method is considered a powerful tool. 221 refs., 138 figs., 36 tabs.

  8. Acute stress may induce ovulation in women.

    Science.gov (United States)

    Tarín, Juan J; Hamatani, Toshio; Cano, Antonio

    2010-05-26

    This study aims to gather information either supporting or rejecting the hypothesis that acute stress may induce ovulation in women. The formulation of this hypothesis is based on 2 facts: 1) estrogen-primed postmenopausal or ovariectomized women display an adrenal-progesterone-induced ovulatory-like luteinizing hormone (LH) surge in response to exogenous adrenocorticotropic hormone (ACTH) administration; and 2) women display multiple follicular waves during an interovulatory interval, and likely during pregnancy and lactation. Thus, acute stress may induce ovulation in women displaying appropriate serum levels of estradiol and one or more follicles large enough to respond to a non-midcycle LH surge. A literature search using the PubMed database was performed to identify articles up to January 2010 focusing mainly on women as well as on rats and rhesus monkeys as animal models of interaction between the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes. Whereas the HPA axis exhibits positive responses in practically all phases of the ovarian cycle, acute-stress-induced release of LH is found under relatively high plasma levels of estradiol. However, there are studies suggesting that several types of acute stress may exert different effects on pituitary LH release and the steroid environment may modulate in a different way (inhibiting or stimulating) the pattern of response of the HPG axis elicited by acute stressors. Women may be induced to ovulate at any point of the menstrual cycle or even during periods of amenorrhea associated with pregnancy and lactation if exposed to an appropriate acute stressor under a right estradiol environment.

  9. Acute stress may induce ovulation in women

    Directory of Open Access Journals (Sweden)

    Cano Antonio

    2010-05-01

    Full Text Available Abstract Background This study aims to gather information either supporting or rejecting the hypothesis that acute stress may induce ovulation in women. The formulation of this hypothesis is based on 2 facts: 1 estrogen-primed postmenopausal or ovariectomized women display an adrenal-progesterone-induced ovulatory-like luteinizing hormone (LH surge in response to exogenous adrenocorticotropic hormone (ACTH administration; and 2 women display multiple follicular waves during an interovulatory interval, and likely during pregnancy and lactation. Thus, acute stress may induce ovulation in women displaying appropriate serum levels of estradiol and one or more follicles large enough to respond to a non-midcycle LH surge. Methods A literature search using the PubMed database was performed to identify articles up to January 2010 focusing mainly on women as well as on rats and rhesus monkeys as animal models of interaction between the hypothalamic-pituitary-adrenal (HPA and hypothalamic-pituitary-gonadal (HPG axes. Results Whereas the HPA axis exhibits positive responses in practically all phases of the ovarian cycle, acute-stress-induced release of LH is found under relatively high plasma levels of estradiol. However, there are studies suggesting that several types of acute stress may exert different effects on pituitary LH release and the steroid environment may modulate in a different way (inhibiting or stimulating the pattern of response of the HPG axis elicited by acute stressors. Conclusion Women may be induced to ovulate at any point of the menstrual cycle or even during periods of amenorrhea associated with pregnancy and lactation if exposed to an appropriate acute stressor under a right estradiol environment.

  10. Tactile Perception and Friction-Induced Vibrations: Discrimination of Similarly Patterned Wood-Like Surfaces.

    Science.gov (United States)

    Dacleu Ndengue, Jessica; Cesini, Ilaria; Faucheu, Jenny; Chatelet, Eric; Zahouani, Hassan; Delafosse, David; Massi, Francesco

    2017-01-01

    The tactile perception of a surface texture is mediated by factors such as material, topography, and vibrations induced by the sliding contact. In this paper, sensory characterizations are developed together with topographical and tribo-tactile characterizations to relate perceived features with objective measurements of tribological and dynamic signals. Two sets of surface samples are used in this study: the first set is made of a commercial floor covering tiles that aim at counter-typing natural wood flooring, with both a visual and a tactile texture mimicking wood. A second set is custom-made by replicating the first set using a plain purple polyurethane resin. The comparison between tribo-tactile signals and sensory analysis allowed the identification of objective indices for textures with slight topographical differences. Even though the topography of the replicated samples is the same as their corresponding commercial products, the fact that the material is different, induces differences in the contact and vibrational parameters. This in turn modifies the discrimination performances during the sensory experiment. Tactile characteristics collected during sensory procedures are found to be in agreement with objective indices such as friction coefficients and induced vibrations.

  11. Non-linear system identification in flow-induced vibration

    Energy Technology Data Exchange (ETDEWEB)

    Spanos, P.D.; Zeldin, B.A. [Rice Univ., Houston, TX (United States); Lu, R. [Hudson Engineering Corp., Houston, TX (United States)

    1996-12-31

    The paper introduces a method of identification of non-linear systems encountered in marine engineering applications. The non-linearity is accounted for by a combination of linear subsystems and known zero-memory non-linear transformations; an equivalent linear multi-input-single-output (MISO) system is developed for the identification problem. The unknown transfer functions of the MISO system are identified by assembling a system of linear equations in the frequency domain. This system is solved by performing the Cholesky decomposition of a related matrix. It is shown that the proposed identification method can be interpreted as a {open_quotes}Gram-Schmidt{close_quotes} type of orthogonal decomposition of the input-output quantities of the equivalent MISO system. A numerical example involving the identification of unknown parameters of flow (ocean wave) induced forces on offshore structures elucidates the applicability of the proposed method.

  12. Radar detection of pedestrian-induced vibrations on Michelangelo's David.

    Science.gov (United States)

    Pieraccini, Massimiliano; Betti, Michele; Forcellini, Davide; Dei, Devis; Papi, Federico; Bartoli, Gianni; Facchini, Luca; Corazzi, Riccardo; Kovacevic, Vladimir Cerisano

    2017-01-01

    This paper summarizes the results of a two-day dynamic monitoring of Michelangelo's David subject to environmental loads (city traffic and pedestrian loading induced by tourists visiting the Accademia Gallery). The monitoring was carried out by a no-contact technique using an interferometric radar, whose effectiveness in measuring the resonant frequencies of structures and historic monuments has proved over the last years through numerous monitoring activities. Owing to the dynamic behavior of the measurement system (radar and tripod), an accelerometer has been installed on the radar head to filter out the movement component of the measuring instrument from the measurement of the David's displacement. Measurements were carried out in the presence and absence of visitors, to assess their influence on the dynamic behavior of the statue. A numerical model of the statue was employed to evaluate the experimental results.

  13. 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.

  14. Diagnosis and control of machine induced noise and vibration in steel construction

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei Yu; Wang, Wei Hui [National Taiwan Ocean University, Keelung (China)

    2008-11-15

    Most high-rise buildings constructed of steel or steel reinforced concrete have to install various vital equipment. Among these equipment machinery noise is especially annoying for accommodation close to them. In attempting to control the machine-induced structure-borne noise and vibration, the methodology by employing mobility functions to identify the dominant frequency band of vibrational power flow transmission and to assess the isolation effectiveness of isolators is established. The proposed method of diagnosis procedure is applied to the structure-borne vibration power flow transmission for a steel construction parking tower. After proper check and replacement of the isolators of the power unit platform of the mechanical parking tower, the improvement results in a substantial structure-borne noise reduction of 16 dB(NC). The unique parts of the paper include the establishment of the relation of mobility functions with respect to four-pole parameters for a coupled machine/mount/foundation system. Also expressions to represent the vibrational input power, the output power and the transmitted power in relation to mobility functions are clarified

  15. 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.

  16. Coupled dynamics of vortex-induced vibration and stationary wall at low Reynolds number

    Science.gov (United States)

    Li, Zhong; Jaiman, Rajeev K.; Khoo, Boo Cheong

    2017-09-01

    The flow past an elastically mounted circular cylinder placed in proximity to a plane wall is numerically studied in both two dimensions (2D) and three dimensions (3D). This paper aims to explain the mechanism of the cylinder bottom shear layer roll-up suppression in the context of laminar vortex-induced vibration (VIV) of a cylinder placed in the vicinity of a plane stationary wall. In 2D simulations, VIV of a near-wall cylinder with structure-to-displaced fluid mass ratios of m* = 2 and 10 is investigated at the Reynolds number of Re = 100 at a representative gap ratio of e/D = 0.90, where e denotes the gap distance between the cylinder surface and the plane wall. First, the cylinder is placed at five different upstream distances, LU, to study the effects of the normalized wall boundary layer thickness, δ /D , on the hydrodynamic quantities involved in the VIV of a near-wall cylinder. It is found that the lock-in range shifts towards the direction of the higher reduced velocity Ur as δ /D increases and that the lock-in range widens as m* reduces. Second, via visualization of the vortex shedding patterns, four different modes are classified and the regime maps are provided for both m* = 2 and 10. Third, the proper orthogonal decomposition analysis is employed to assess the cylinder bottom shear layer roll-up suppression mechanism. For 3D simulations at Re = 200, the circular cylinder of a mass ratio of m* = 10 with a spanwise length of 4D is placed at a gap ratio of e/D = 0.90 and an upstream distance of LU = 10D. The 3D vortex patterns are investigated to re-affirm the vortex shedding suppression mechanism. The pressure distributions around the cylinder are identified within one oscillation cycle of VIV. The pressure and the shear stress distributions on the bottom wall are examined to demonstrate the effects of near-wall VIV on the force distributions along the plane wall. It is found that both the suction pressure and the shear stress right below the cylinder

  17. Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters

    Science.gov (United States)

    Sharpes, Nathan; Abdelkefi, Abdessattar; Priya, Shashank

    2015-08-01

    Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm2 area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.

  18. A general higher-order nonlocal couple stress based beam model for vibration analysis of porous nanocrystalline nanobeams

    Science.gov (United States)

    Ebrahimi, Farzad; Barati, Mohammad Reza

    2017-12-01

    This paper develops a higher order refined beam model with a parabolic shear strain function for vibration analysis of porous nanocrystalline nanobeams based on nonlocal couple stress theory. Nanocrystalline nanobeam is composed from three phases which are nano-grains, nano-voids and interface. Nano-voids or porosities inside the material have a stiffness-softening impact on the nanobeam. Nonlocal elasticity theory of Eringen is applied in analysis of nanocrystalline nanobeams for the first time. Also, modified couple stress theory is employed to capture grains rigid rotations. The governing equations obtained from Hamilton's principle are solved applying an analytical approach which satisfies various boundary conditions. The reliability of present approach is verified by comparing obtained results with those provided in literature. Finally the influences of nonlocal parameter, couple stress, grain size, porosities and shear deformation on the vibration characteristics of nanocrystalline nanobeams are explored.

  19. Three-dimensional solutions for the free vibrations and buckling of thermally stressed multilayered angle-ply composite plates

    Science.gov (United States)

    Noor, Ahmed K.; Burton, W. S.

    1992-01-01

    Analytic three-dimensional elasticity solutions are developed for the free vibration and buckling of thermally stressed rectangular multilayered angle-ply anisotropic plates which are assumed to have an antisymmetric lamination with respect to the middle plane. Sensitivity derivatives are evaluated and used to investigate the sensitivity of the vibration and buckling responses to variations in the different lamination and material parameters of the plate. A Duhamel-Neumann-type constitutive model is used, and the material properties are assumed to be independent of temperature. Numerical results are presented, showing the effects of variations in the material characteristics and fiber orientation of different layers, as well as the effect of initial thermal deformation on the vibrational and buckling responses of the plate.

  20. Analytical Model of Underground Train Induced Vibrations on Nearby Building Structures in Cameroon: Assessment and Prediction

    Directory of Open Access Journals (Sweden)

    Lezin Seba MINSILI

    2013-11-01

    Full Text Available The purpose of this research paper was to assess and predict the effect of vibrations induced by an underground railway on nearby-existing buildings prior to the construction of projected new railway lines of the National Railway Master Plan of Cameroon and after upgrading of the railway conceded to CAMRAIL linking the two most densely populated cities of Cameroon: Douala and Yaoundé. With the source-transmitter-receiver mathematical model as the train-soil-structure interaction model, taking into account sub-model parameters such as type of the train-railway system, typical geotechnical conditions of the ground and the sensitivity of the nearby buildings, the analysis is carried out over the entire system using the dynamic finite element method in the time domain. This subdivision of the model is a powerful tool that allows to consider different alternatives of sub-models with different characteristics, and thus to determine any critical excessive vibration impact. Based on semi-empirical analytical results obtained from presented models, the present work assesses and predicts characteristics of traffic-induced vibrations as a function of time duration, intensity and vehicle speed, as well as their influence on buildings at different levels.

  1. Effect of Induced Vibration on the Blood Flow Properties in a Mechanical Aortic Valve

    Directory of Open Access Journals (Sweden)

    Kadhim Saleem Khalefa

    2014-07-01

    Full Text Available The effect of induced vibration on velocity distribution for the blood flow in the bileaflet mechanical heart valves conveying blood was investigated in this study. The bileaflet valve was simulated as an orifice. The induced vibration is due to the pulsed blood flow in the artery. Results presented in this study were performed using CFD FLUENT software. This analysis is based on the non-linear numerical solution by using a finite-element method, for the system of governing partial differential equations (continuity, momentum of Navier - Stokes equation of blood flow through the orifice. It has been found that as the flow through the orifice increased, the vibration at the orifice inlet increased. For steady state conditions, at Reynolds number 50 the recorded frequency was 20Hz. When the Reynolds number increased to 100 due to the increase in the blood flow the recorded frequency increased to 30Hz. The increase in frequency may result in damaging the blood red cells and platelets which subsequently results in increasing the blood clogging downstream of the orifice.

  2. Modal Analysis and Measurement of Water Cooling Induced Vibrations on a CLIC Main Beam Quadrupole Prototype

    CERN Document Server

    Artoos, K; Esposito, M; Fernandez Carmona, P; Guinchard, M; Janssens, S; Leuxe, R; Modena, M; Moron Ballester, R; Struik, M; Deleglise, C; Jeremie, A

    2011-01-01

    To reach the Compact Linear Collider (CLIC) design luminosity, the mechanical jitter of the CLIC main beam quadrupoles should be smaller than 1.5 nm integrated root mean square (r.m.s.) displacement above 1 Hz. A stiff stabilization and nano-positioning system is being developed but the design and effectiveness of such a system will greatly depend on the stiffness of the quadrupole magnet which should be as high as possible. Modal vibration measurements were therefore performed on a first assembled prototype magnet to evaluate the different mechanical modes and their frequencies. The results were then compared with a Finite Element (FE) model. The vibrations induced by water-cooling without stabilization were measured with different flow rates. This paper describes and analyzes the measurement results.

  3. Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

    2009-05-07

    Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

  4. Smooth polishing of femtosecond laser induced craters on cemented carbide by ultrasonic vibration method

    Science.gov (United States)

    Wang, H. P.; Guan, Y. C.; Zheng, H. Y.

    2017-12-01

    Rough surface features induced by laser irradiation have been a challenging for the fabrication of micro/nano scale features. In this work, we propose hybrid ultrasonic vibration polishing method to improve surface quality of microcraters produced by femtosecond laser irradiation on cemented carbide. The laser caused rough surfaces are significantly smoothened after ultrasonic vibration polishing due to the strong collision effect of diamond particles on the surfaces. 3D morphology, SEM and AFM analysis has been conducted to characterize surface morphology and topography. Results indicate that the minimal surface roughness of Ra 7.60 nm has been achieved on the polished surfaces. The fabrication of microcraters with smooth surfaces is applicable to molding process for mass production of micro-optical components.

  5. Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

    Science.gov (United States)

    Yang, Yang; Pan, Yayue; Guo, Ping

    2017-04-01

    Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

  6. Coupled analysis of multi-impact energy harvesting from low-frequency wind induced vibrations

    Science.gov (United States)

    Zhu, Jin; Zhang, Wei

    2015-04-01

    Energy need from off-grid locations has been critical for effective real-time monitoring and control to ensure structural safety and reliability. To harvest energy from ambient environments, the piezoelectric-based energy-harvesting system has been proven very efficient to convert high frequency vibrations into usable electrical energy. However, due to the low frequency nature of the vibrations of civil infrastructures, such as those induced from vehicle impacts, wind, and waves, the application of a traditional piezoelectric-based energy-harvesting system is greatly restrained since the output power drops dramatically with the reduction of vibration frequencies. This paper focuses on the coupled analysis of a proposed piezoelectric multi-impact wind-energy-harvesting device that can effectively up-convert low frequency wind-induced vibrations into high frequency ones. The device consists of an H-shape beam and four bimorph piezoelectric cantilever beams. The H-shape beam, which can be easily triggered to vibrate at a low wind speed, is originated from the first Tacoma Narrows Bridge, which failed at wind speeds of 18.8 m s-1 in 1940. The multi-impact mechanism between the H-shape beam and the bimorph piezoelectric cantilever beams is incorporated to improve the harvesting performance at lower frequencies. During the multi-impact process, a series of sequential impacts between the H-shape beam and the cantilever beams can trigger high frequency vibrations of the cantilever beams and result in high output power with a considerably high efficiency. In the coupled analysis, the coupled structural, aerodynamic, and electrical equations are solved to obtain the dynamic response and the power output of the proposed harvesting device. A parametric study for several parameters in the coupled analysis framework is carried out including the external resistance, wind speed, and the configuration of the H-shape beam. The average harvested power for the piezoelectric cantilever

  7. Ethanol-induced oxidative stress: basic knowledge

    Science.gov (United States)

    Signorini, Cinzia; Leoncini, Silvia; Gardi, Concetta; Ciccoli, Lucia; Giardini, Anna; Vecchio, Daniela; Arezzini, Beatrice

    2009-01-01

    After a general introduction, the main pathways of ethanol metabolism (alcohol dehydrogenase, catalase, coupling of catalase with NADPH oxidase and microsomal ethanol-oxidizing system) are shortly reviewed. The cytochrome P450 isoform (CYP2E1) specifically involved in ethanol oxidation is discussed. The acetaldehyde metabolism and the shift of the NAD/NADH ratio in the cellular environment (reductive stress) are stressed. The toxic effects of acetaldehyde are mentioned. The ethanol-induced oxidative stress: the increased MDA formation by incubated liver preparations, the absorption of conjugated dienes in mitochondrial and microsomal lipids and the decrease in the most unsaturated fatty acids in liver cell membranes are discussed. The formation of carbon-centered (1-hydroxyethyl) and oxygen-centered (hydroxyl) radicals during the metabolism of ethanol is considered: the generation of hydroxyethyl radicals, which occurs likely during the process of univalent reduction of dioxygen, is highlighted and is carried out by ferric cytochrome P450 oxy-complex (P450–Fe3+O2·−) formed during the reduction of heme-oxygen. The ethanol-induced lipid peroxidation has been evaluated, and it has been shown that plasma F2-isoprostanes are increased in ethanol toxicity. PMID:20606811

  8. Simulations of vortex-induced vibrations of long cylinders with two degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Bell, T.A.; Militzer, J. [Dalhousie Univ., Dept. of Mechanical Engineering, Halifax, Nova Scotia (Canada)]. E-mail: tabell@dal.ca; Julio.Militzer@dal.ca; Ham, F. [Stanford Univ., Center for Turbulence Research, Stanford, California (United States)]. E-mail: fham@stanford.edu

    2003-07-01

    Long cylindrical risers are required for deep water exploration and production of petroleum or natural gas. The flow of seawater around these long cylinders is subject to vortex shedding. This is an unsteady oscillatory phenomenon, which causes the pressure distribution around the cylinders to fluctuate. If the vortex shedding frequency is equal to a natural frequency of the riser, then the vortex shedding will induce the riser to vibrate. These are known are Vortex Induced Vibrations or VIV. These vibrations cause premature fatigue or clashing between neighbouring risers. In the current contribution we carry out an unsteady two-dimensional numerical simulation of VIV. The numerical algorithm incorporates several desirable features for such simulations, namely, it uses an adaptive non-isotropic Cartesian grid and the Immersed Boundary Method for boundary condition specification around the cylinder. The current simulations use LES with a Smagorinsky model to calculate the effective viscosity. Its main advantage, however, is the ability to easily handle flows with moving boundaries. The cylinder is assumed to be 1800 m long with a diameter of 0.25 m and subjected to traction force of 10{sup 6} N, with a flow Reynolds number of 8640. The cylinder vibration is assumed to lock in to the 2nd natural mode with a frequency of 0.0473 Hz. At each time step the flow velocity and pressure distributions are calculated. The pressure distribution around the cylinder is used to calculate the drag and lift coefficients. This information is then used to solve two 2nd order simple harmonic motion ODEs, which give the velocity and displacement of the cylinder in cross flow and stream-wise directions. This information is used to update the position of the cylinder and its velocity. Most results available in the literature for cylinders subjected to vortex induced forces are limited to either stationary or one degree of freedom (usually compare the results for a rigid cylinder, a

  9. Integrated Advanced Microwave Sounding Unit-A (AMSU-A) METOP Stress Analysis Report (Qual Level Random Vibration) A1 Module

    Science.gov (United States)

    Mehitretter, R.

    1996-01-01

    Stress analysis of the primary structure of the Meteorological Satellites Project (METSAT) Advanced Microwave Sounding Units-A, A1 Module performed using the Meteorological Operational (METOP) Qualification Level 9.66 grms Random Vibration PSD Spectrum is presented. The random vibration structural margins of safety and natural frequency predictions are summarized.

  10. A Refined Higher-Order Hybrid Stress Quadrilateral Element for Free Vibration and Buckling Analyses of Reissner-Mindlin Plates

    Directory of Open Access Journals (Sweden)

    Tan Li

    2017-01-01

    Full Text Available This paper is devoted to develop a new 8-node higher-order hybrid stress element (QH8 for free vibration and buckling analysis based on the Mindlin/Reissner plate theory. In particular, a simple explicit expression of a refine method with an adjustable constant is introduced to improve the accuracy of the analysis. A combined mass matrix for natural frequency analysis and a combined geometric stiffness matrix for buckling analysis are obtained using the refined method. It is noted that numerical examples are presented to show the validity and efficiency of the present element for free vibration and buckling analysis of plates. Furthermore, satisfactory accuracy for thin and moderately thick plates is obtained and it is free from shear locking for thin plate analysis and can pass the nonzero shear stress patch test.

  11. Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters

    Energy Technology Data Exchange (ETDEWEB)

    Sharpes, Nathan [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Abdelkefi, Abdessattar [Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2015-08-31

    Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm{sup 2} area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.

  12. Vibration-induced extra torque during electrically-evoked contractions of the human calf muscles

    Directory of Open Access Journals (Sweden)

    Kohn André F

    2010-06-01

    stimulation could be beneficial for many therapeutic interventions and vibration-based exercise programs. The command for the vibration-induced extra torques presumably activates spinal motoneurons following the size principle, which is a desirable feature for stimulation paradigms.

  13. Reduced plantar sole sensitivity induces balance control modifications to compensate ankle tendon vibration and vision deprivation.

    Science.gov (United States)

    Billot, Maxime; Handrigan, Grant A; Simoneau, Martin; Teasdale, Normand

    2015-02-01

    The aim of this study was to investigate if sensory reweighting occurred to control balance when the sensitivity of the plantar sole is reduced using cooling. To address this question, visual information was manipulated and/or ankle proprioception was altered by Achilles tendon vibration. It was expected that Achilles tendon vibration and vision deprivation would induce greater center of pressure (CoP) excursions and/or increase of electromyographic (EMG) activity of the ankle muscles (triceps surea and tibialis anterior) with than without cooling of the plantar sole. To verify these hypotheses, the CoP and EMG activity of the ankle muscles were simultaneously recorded during quiet standing trials of 30s before and after feet cooling procedure. Results showed that plantar sole sensitivity alteration did not lead to larger CoP excursions even during Achilles tendon vibration in absence of vision. This could be explained by an increase in the EMG activity of the triceps surae after the cooling procedure without modification of tibialis anterior EMG activity. This study suggests that to compensate alteration in plantar sole sensitivity, the central nervous system increased the muscular activity of the triceps surae to limit CoP excursions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Prediction of Acoustically Induced Random Vibration Response of Satellite Equipments with Proposed Asymptotic Apparent Mass

    Science.gov (United States)

    Ando, Shigemasa; Shi, Qinzhong

    Acoustically induced random vibration of satellite equipment mounted on honeycomb panels is a critical design consideration in satellite equipment development. Prediction of this random vibration is performed in the early stage of satellite design to specify the design limit value of random vibration excitation for satellite equipment. Various prediction methods for response prediction using Statistical Energy Analysis (SEA) have been developed: (i) NASA Lewis method, (ii) point-mass impedance method, and (iii) area-coupling impedance method. However, the first method has limited accuracy for heavy and concentrated equipment, the second one often overestimates, and the third one requires a detailed parameter. A new method combining the asymptotic apparent mass of specific equipment with NASA Lewis method is proposed herein. This proposed method takes the elastic behavior of satellite equipment rather than a rigid mass. The acoustic excitation experiments for nine real satellites (404 equipments in all) were conducted to compare existing methods to the proposed method statistically. Results show that the proposed method provides the most accurate prediction in the important frequency range.

  15. Numerical simulations of the dynamic of steel catenary riser under the influence of VIV-Vortex-Induced Vibration

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, Raphael I.; Morooka, Celso K. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Franciss, Ricardo; Matt, Cyntia G.C. [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2009-07-01

    Hydrocarbon discoveries in ultra deep waters and the recent pre-salt deep carbonate reservoirs along the Brazilian coast demand further technological development in order to exploit these resources. These developments usually require new concepts for offshore sea surface structures and subsea systems for the petroleum and gas production, which means cost effective solutions that provides higher operational safety on drilling and production operations. In this scenario, the effect of the natural phenomenon of Vortex-Induced Vibration (VIV) on risers is one of the concerns for its design due to the tendency of VIV to increase levels of stresses in the riser structure. Therefore the correct prediction of stresses and displacements due to VIV is of great importance for designing riser systems. The present work presents new developments based on previous results for VIV in vertical risers extended to curved risers such as steel catenary risers (SCR). Numerical simulations have been performed in time domain, and experimental results from model tests with a scaled SCR in a towing tank have been used to evaluate the proposed developments. Finally, the conclusions from the analysis of the results bring very promising results. (author)

  16. Collaboratively Adaptive Vibration Sensing System for High-fidelity Monitoring of Structural Responses Induced by Pedestrians

    Directory of Open Access Journals (Sweden)

    Shijia Pan

    2017-05-01

    Full Text Available This paper presents a collaboratively adaptive vibration monitoring system that captures high-fidelity structural vibration signals induced by pedestrians. These signals can be used for various human activities’ monitoring by inferring information about the impact sources, such as pedestrian footsteps, door opening and closing, and dragging objects. Such applications often require high-fidelity (high resolution and low distortion signals. Traditionally, expensive high resolution and high dynamic range sensors are adopted to ensure sufficient resolution. However, for sensing systems that use low-cost sensing devices, the resolution and dynamic range are often limited; hence this type of sensing methods is not well explored ubiquitously. We propose a low-cost sensing system that utilizes (1 a heuristic model of the investigating excitations and (2 shared information through networked devices to adapt hardware configurations and obtain high-fidelity structural vibration signals. To further explain the system, we use indoor pedestrian footstep sensing through ambient structural vibration as an example to demonstrate the system performance. We evaluate the application with three metrics that measure the signal quality from different aspects: the sufficient resolution rate to present signal resolution improvement without clipping, the clipping rate to measure the distortion of the footstep signal, and the signal magnitude to quantify the detailed resolution of the detected footstep signal. In experiments conducted in a school building, our system demonstrated up to 2× increase on the sufficient resolution rate and 2× less error rate when used to locate the pedestrians as they walk along the hallway, compared to a fixed sensing setting.

  17. Occurrence of fatigue induced by a whole-body vibration session is not frequency dependent.

    Science.gov (United States)

    Zory, Raphael F; Raphael, Zory F; Aulbrook, Wesley; Wesley, Aulbrook; Keir, Daniel A; Daniel, Keir A; Serresse, Olivier; Olivier, Serresse

    2013-09-01

    The aim of this study was to determine whether neuromuscular adaptations (magnitude and location) induced by isometric exercise performed on an oscillating platform are dependent on whole-body vibration (WBV) frequency. Eleven young men performed 4 separate fatigue sessions of static squatting exercise at 3 frequencies of WBV (V20, V40, and V60) and 1 session without vibration (V0). Isometric torque and electromyographic activity of the vastus lateralis, rectus femoris, and biceps femoris were recorded during maximal voluntary and evoked contractions of the knee extensor muscles before and after each fatigue session to examine both peripheral and central adaptations. Isometric torque decreased significantly after each of the 4 frequency sessions (V0: -9.4 ± 6.1%, p = 0.003; V20: -8.1 ± 9.9%, p = 0.010; V40: -11.9 ± 12.7%, p = 0.011; and V60: -7.8 ± 9.2%, p = 0.001, respectively), but this reduction was not significantly different between frequencies. The torque produced by evoked contraction significantly decreased from pre-exercise values after each session (V0: -14.9 ± 15.6%, p = 0.012; V20: -15.8 ± 16.4%, p = 0.010; V40: -21.0 ± 14.3%, p = 0.004; and V60: -17.3 ± 11.6%, p = 0.005, respectively); however, there was no effect of vibration frequency. In both conditions, the maximal voluntary contraction torque reduction observed was mainly attributable to peripheral fatigue and was not because of central modifications of the neuromuscular system. The present study demonstrates that the frequency of vibration does not significantly influence the magnitude and location of neuromuscular fatigue, suggesting that adding WBV to static squat exercise (on a vertically oscillating platform) does not provide an additional training stimulus.

  18. Symposium on Flow-Induced Vibrations Held in New Orleans, Louisiana on 9-14 December 1984. Volume 1. Excitation and Vibration of Bluff Bodies in Cross Flow

    Science.gov (United States)

    1984-12-14

    goes back to the time of Leonardo da Vinci , and even to the first mention in anticuity of the wind-induced vibration and sound of the Aeolian harp...Cylinder material Investigator( s ) A Flexible Water PVC King (1977T - *cantilever PVC Aluminum Stainle3s steel 0 Pivoted Water Brass Vickery and rigid...case of flexible, cylindrical marine structures by Griffin (41 in a study of OTEC cold water pipe vibra- tions. Measurements of the drag coefficient

  19. Comparative assessment of different treatment modalities in miners with vibration- and noise-induced disease

    Energy Technology Data Exchange (ETDEWEB)

    Velskaya, M.L.; Nekhorosheva, M.A.; Konovalova, S.I.; Kukhtina, G.V.; Gonchar, I.G.; Terentyeva, D.P.; Grishchenko, L.A.; Soboleva, N.P.; Kharitonov, S.A.; Priklonskiy, I.V.

    1985-02-01

    A group of 71 miners with vibration sickness and noise-induced pathology were managed either by standard methods, or in combination with acupuncture and/or hyperbaric oxygenation for a comparative assessment of the effectiveness of the different therapeutic approaches. Analysis of subjective factors as well as standard physiological parameters (EKG, rheoencephalography, peripheral rheography, EEG, neuropsychological tests) demonstrate that both acupuncture and hyperbaric oxygenation are effective modalities in the majority of the subjects. Nevertheless, the lack of improvement in certain criteria, or even what could be regarded as adverse sequelae, suggest that the use of hyperbaric oxygenation in the management of such disorders be approached with considerable care.

  20. Accelerated Vibration Test of coolant channel components under simulated flow induced excitation

    Energy Technology Data Exchange (ETDEWEB)

    Meher, K.K., E-mail: kkmeher@barc.gov.in; Pandey, J.K., E-mail: jkpandey@barc.gov.in; RamaRao, A., E-mail: arr@barc.gov.in

    2016-04-15

    Highlights: • The present study deals with the issue of loosening of the nut in the Grayloc joint due to flow induced vibration and fret in the feeder pipes in contact due to differential creep in the neighbouring channels. • Accelerated test has been done on the Grayloc joint on simulated flow induced vibration to study the effect of loosening of the nut. • In the present accelerated test, the component has not been led to failure (loosening) and an estimation of its service life has been approached based on the severity of test. • The inverse square law approach based on PSD comparison for severity of test have been used to correlate the actual operational hours and the Laboratory test hours to verify the loosening of the Grayloc nut for the present study. • By inverse power law approach, the minimum number of reactor-hours equivalent to 80 h of testing is 46,080 h (5.26 full power years). - Abstract: The present study outlines the accelerated testing procedure of a Grayloc joint assembly for possible loosening of its nut due to flow induced vibration. The concern of the Grayloc nut getting loosened in the absence of a lock nut due to flow induced vibration and the resulting fretting in the feeder pipes in contact due to differential creep in the neighbouring channels has been addressed here. The severity of the test was decided based on actual site measurement under different operating flow conditions and comparison of power spectral density (PSD). The laboratory test results were extrapolated for estimation of life of the component under operating condition using inverse power law approach. The uniqueness of the accelerated test is that the component under test has not been led to failure for assessing its operating life unlike conventional accelerated testing. From the tests and analysis, it was deduced that 80 h of accelerated laboratory testing was equivalent to 5.26 full power years (46,080 h) of the reactor operating life. The test duration was

  1. Melamine Induces Oxidative Stress in Mouse Ovary.

    Directory of Open Access Journals (Sweden)

    Xiao-Xin Dai

    Full Text Available Melamine is a nitrogen heterocyclic triazine compound which is widely used as an industrial chemical. Although melamine is not considered to be acutely toxic with a high LD50 in animals, food contaminated with melamine expose risks to the human health. Melamine has been reported to be responsible for the renal impairment in mammals, its toxicity on the reproductive system, however, has not been adequately assessed. In the present study, we examined the effect of melamine on the follicle development and ovary formation. The data showed that melamine increased reactive oxygen species (ROS levels, and induced granulosa cell apoptosis as well as follicle atresia. To further analyze the mechanism by which melamine induces oxidative stress, the expression and activities of two key antioxidant enzymes superoxide dismutase (SOD and glutathione peroxidase (GPX were analyzed, and the concentration of malondialdehyde (MDA were compared between control and melamine-treated ovaries. The result revealed that melamine changed the expression and activities of SOD and GPX in the melamine-treated mice. Therefore, we demonstrate that melamine causes damage to the ovaries via oxidative stress pathway.

  2. Smog induces oxidative stress and microbiota disruption

    Directory of Open Access Journals (Sweden)

    Tit-Yee Wong

    2017-04-01

    Full Text Available Smog is created through the interactions between pollutants in the air, fog, and sunlight. Air pollutants, such as carbon monoxide, heavy metals, nitrogen oxides, ozone, sulfur dioxide, volatile organic vapors, and particulate matters, can induce oxidative stress in human directly or indirectly through the formation of reactive oxygen species. The outermost boundary of human skin and mucous layers are covered by a complex network of human-associated microbes. The relation between these microbial communities and their human host are mostly mutualistic. These microbes not only provide nutrients, vitamins, and protection against other pathogens, they also influence human's physical, immunological, nutritional, and mental developments. Elements in smog can induce oxidative stress to these microbes, leading to community collapse. Disruption of these mutualistic microbiota may introduce unexpected health risks, especially among the newborns and young children. Besides reducing the burning of fossil fuels as the ultimate solution of smog formation, advanced methods by using various physical, chemical, and biological means to reduce sulfur and nitrogen contains in fossil fuels could lower smog formation. Additionally, information on microbiota disruption, based on functional genomics, culturomics, and general ecological principles, should be included in the risk assessment of prolonged smog exposure to the health of human populations.

  3. The Skull Vibration-Induced Nystagmus Test of Vestibular Function—A Review

    Science.gov (United States)

    Dumas, Georges; Curthoys, Ian S.; Lion, Alexis; Perrin, Philippe; Schmerber, Sébastien

    2017-01-01

    A 100-Hz bone-conducted vibration applied to either mastoid induces instantaneously a predominantly horizontal nystagmus, with quick phases beating away from the affected side in patients with a unilateral vestibular loss (UVL). The same stimulus in healthy asymptomatic subjects has little or no effect. This is skull vibration-induced nystagmus (SVIN), and it is a useful, simple, non-invasive, robust indicator of asymmetry of vestibular function and the side of the vestibular loss. The nystagmus is precisely stimulus-locked: it starts with stimulation onset and stops at stimulation offset, with no post-stimulation reversal. It is sustained during long stimulus durations; it is reproducible; it beats in the same direction irrespective of which mastoid is stimulated; it shows little or no habituation; and it is permanent—even well-compensated UVL patients show SVIN. A SVIN is observed under Frenzel goggles or videonystagmoscopy and recorded under videonystagmography in absence of visual-fixation and strong sedative drugs. Stimulus frequency, location, and intensity modify the results, and a large variability in skull morphology between people can modify the stimulus. SVIN to 100 Hz mastoid stimulation is a robust response. We describe the optimum method of stimulation on the basis of the literature data and testing more than 18,500 patients. Recent neural evidence clarifies which vestibular receptors are stimulated, how they cause the nystagmus, and why the same vibration in patients with semicircular canal dehiscence (SCD) causes a nystagmus beating toward the affected ear. This review focuses not only on the optimal parameters of the stimulus and response of UVL and SCD patients but also shows how other vestibular dysfunctions affect SVIN. We conclude that the presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears, but in order to identify which is the affected ear, other information and careful clinical judgment are

  4. Non-traditional vibration mitigation methods for reciprocating compressor system

    NARCIS (Netherlands)

    Eijk, A.; Lange, T.J. de; Vreugd, J. de; Slis, E.J.P.

    2016-01-01

    Reciprocating compressors generate vibrations caused by pulsation-induced forces, mechanical (unbalanced) free forces and moments, crosshead guide forces and cylinder stretch forces. The traditional way of mitigating the vibration and cyclic stress levels to avoid fatigue failure of parts of the

  5. Wind-Induced Vibration Control of Dalian International Trade Mansion by Tuned Liquid Dampers

    Directory of Open Access Journals (Sweden)

    Hong-Nan Li

    2012-01-01

    Full Text Available This paper focuses on the wind-induced vibration control of the Dalian international trade mansion (DITM by using the tuned liquid dampers (TLDs. To avoid the intensive computationally demanding problem caused by tens of thousand of degrees of freedom (DOF of the structure in the numerical analysis, the three-dimension finite element model of the DITM is first simplified to the equivalent series multi-DOF system. The wind loading is subsequently simulated by the Davenport model according to the structural environmental condition where the actual samples of wind speed are measured. Following that, the shallow- and deep-water wave theories are applied to model the liquid sloshing inside TLDs, the tank sizing, and required water depth, and numbers of TLDs are given according to the numerical results of different cases. Comparisons between uncontrolled and controlled displacement and acceleration responses of the DITM under wind forces show that the designed shallow tank has higher efficiency than the deep one, which can effectively reduce the structural response amplitudes and enhance the comfortableness of the mansion. The preliminary TLD design procedure presented in this paper could be applied as a reference to the analysis and design of the wind-induced vibration for high-rise buildings using the TLD.

  6. Enhancement of wind energy harvesting by interaction between vortex-induced vibration and galloping

    Science.gov (United States)

    He, Xuefeng; Yang, Xiaokang; Jiang, Senlin

    2018-01-01

    Most wind energy harvesters (WEHs) that have been reported in the literature collect wind energy using only one type of wind-induced vibration, such as vortex-induced vibration (VIV), galloping, and flutter or wake galloping. In this letter, the interaction between VIV and galloping is used to improve the performance of WEHs. For a WEH constructed by attaching a bluff body with a rectangular cross-section to the free end of a piezoelectric cantilever, the measures to realize the interaction are theoretically discussed. Experiments verified the theoretical prediction that the WEHs with the same piezoelectric beam may demonstrate either separate or interactive VIV and galloping, depending on the geometries of the bluff bodies. For the WEHs with the interaction, the wind speed region of the VIV merges with that of the galloping to form a single region with high electrical outputs, which greatly increases the electrical outputs at low wind speeds. The interaction can be realized even when the predicted galloping critical speed is much higher than the predicted VIV critical speed. The proposed interaction is thus an effective approach to improve the scavenging efficiencies of WEHs operating at low wind speeds.

  7. The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available Based on forced vibration tests for high-performance concrete (HPC, the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

  8. Vibration and stress analysis of soft-bonded shuttle insulation tiles. Modal analysis with compact widely space stringers

    Science.gov (United States)

    Ojalvo, I. U.; Austin, F.; Levy, A.

    1974-01-01

    An efficient iterative procedure is described for the vibration and modal stress analysis of reusable surface insulation (RSI) of multi-tiled space shuttle panels. The method, which is quite general, is rapidly convergent and highly useful for this application. A user-oriented computer program based upon this procedure and titled RESIST (REusable Surface Insulation Stresses) has been prepared for the analysis of compact, widely spaced, stringer-stiffened panels. RESIST, which uses finite element methods, obtains three dimensional tile stresses in the isolator, arrestor (if any) and RSI materials. Two dimensional stresses are obtained in the tile coating and the stringer-stiffened primary structure plate. A special feature of the program is that all the usual detailed finite element grid data is generated internally from a minimum of input data. The program can accommodate tile idealizations with up to 850 nodes (2550 degrees-of-freedom) and primary structure idealizations with a maximum of 10,000 degrees-of-freedom. The primary structure vibration capability is achieved through the development of a new rapid eigenvalue program named ALARM (Automatic LArge Reduction of Matrices to tridiagonal form).

  9. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    National Research Council Canada - National Science Library

    Manke, Amruta; Wang, Liying; Rojanasakul, Yon

    2013-01-01

    .... Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration...

  10. Comparison of Vibrations and Emissions of Conventional Jet Fuel with Stressed 100% SPK and Fully Formulated Synthetic Jet Fuel

    Directory of Open Access Journals (Sweden)

    Bhupendra Khandelwal

    2014-08-01

    Full Text Available The rapid growth of the aviation sector around the globe has witnessed an overwhelming impact on fossil fuel resources. With the implementation of stricter environmental laws over emissions by conventional jet fuels, growing demand for research on alternative fuels has become imperative. One-hundred percent Synthetic Paraffinic Kerosene (SPK and Fully Formulated Synthetic Jet Fuel have surfaced as viable alternatives for gas turbine engines due to their similar properties as that of Jet Fuel. This paper presents results from an experimental study performed on a small gas turbine engine, comparing emissions performance and vibrations for conventional Jet A-1 Fuel, thermally stressed 100% SPK and Fully Formulated Synthetic Jet Fuel. Different vibration frequencies, power spectra were observed for different fuels. Gaseous emissions observed were nearly the same, whereas, significant changes in particulates emissions were observed.

  11. Pre-cold stress increases acid stress resistance and induces amino ...

    African Journals Online (AJOL)

    Pre-cold stress increases acid stress resistance and induces amino acid homeostasis in Lactococcus lactis NZ9000. ... Compared to exposure to acid stress only, pre-adaptation to cold stress decreased the redox balance ratio and the formation of hydroxyl radicals, indicating a change in aerobic respiration and oxidative ...

  12. Vortex-induced vibrations of a DU96-W-180 airfoil at 90° angle of attack

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Sørensen, Niels N.

    2014-01-01

    This work presents an analysis of vortex-induced vibrations of a DU96-W-180 airfoil in deep stall at a 90 degrees angle of attack, based on 2D and 3D Reynolds Averaged Navier Stokes and 3D Detached Eddy Simulation unsteady Computational Fluid Dynamics computations with non-moving, prescribed motion...... motion. Even though the 2D computations seemed to be capable of indicating the presence of vortex-induced vibrations, the 3D computations seemed to reflect the involved physics more accurately. Copyright (c) 2013 John Wiley & Sons, Ltd....

  13. Stress induced obesity: lessons from rodent models of stress

    OpenAIRE

    Zachary Robert Patterson; Alfonso Bucio Abizaid

    2013-01-01

    Stress was once defined as the non-specific result of the body to any demand or challenge to homeostasis. A more current view of stress is the behavioral and physiological responses generated in the face of, or in anticipation of, a perceived threat. The stress response involves activation of the sympathetic nervous system and recruitment of the hypothalamic-pituitary-adrenal (HPA) axis. When an organism encounters a stressor (social, physical, etc.), these endogenous stress systems are stimu...

  14. Cell death induced by endoplasmic reticulum stress

    National Research Council Canada - National Science Library

    Iurlaro, Raffaella; Muñoz‐Pinedo, Cristina

    2016-01-01

    .... Many conditions that impose stress on cells, including hypoxia, starvation, infections and changes in secretory needs, challenge the folding capacity of the cell and promote endoplasmic reticulum stress...

  15. 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.

  16. A study on anti-stress property of Nardostachys jatamamsi on stress induced Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Shilpashree R.

    2011-09-01

    Full Text Available Stress is a feeling that’s created when we react to particular events. It s the body’s way of rising to a challenge and preparing to meet a tough situation with focus, strength, stamina, and heightened alertness. As a result of the stress immune system can be suppressed by chronic stress opening to increased infections and increasing the risk of autoimmune diseases. So one has to learn away to overcome stress. Here is an attempt made to overcome the stress induced in Drosophila melanogaster a model organism, in this study. Methotrexate is used to induce the stress at different concentration taking different group of flies and a Nardostachys jatamamsi plant extract having antistress property is used to relieve the stress induced. This stress relieve measured by the various stress related enzymes like catalase and Superoxide dismutase by this antistress property of the plant Nardostachys jatamamsi was shown.

  17. On the Shaker Simulation of Wind-Induced Non-Gaussian Random Vibration

    Directory of Open Access Journals (Sweden)

    Fei Xu

    2016-01-01

    Full Text Available Gaussian signal is produced by ordinary random vibration controllers to test the products in the laboratory, while the field data is usually non-Gaussian. Two methodologies are presented in this paper for shaker simulation of wind-induced non-Gaussian vibration. The first methodology synthesizes the non-Gaussian signal offline and replicates it on the shaker in the Time Waveform Replication (TWR mode. A new synthesis method is used to model the non-Gaussian signal as a Gaussian signal multiplied by an amplitude modulation function (AMF. A case study is presented to show that the synthesized non-Gaussian signal has the same power spectral density (PSD, probability density function (PDF, and loading cycle distribution (LCD as the field data. The second methodology derives a damage equivalent Gaussian signal from the non-Gaussian signal based on the fatigue damage spectrum (FDS and the extreme response spectrum (ERS and reproduces it on the shaker in the closed-loop frequency domain control mode. The PSD level and the duration time of the derived Gaussian signal can be manipulated for accelerated testing purpose. A case study is presented to show that the derived PSD matches the damage potential of the non-Gaussian environment for both fatigue and peak response.

  18. Vortex-induced vibrations of a cylinder in planar shear flow

    Science.gov (United States)

    Gsell, Simon; Bourguet, Remi; Braza, Marianna

    2017-11-01

    Vortex-induced vibrations (VIV) of bluff bodies are common in nature and in engineering applications where flexible or flexibly mounted structures are exposed to wind and ocean currents. VIV have been thoroughly studied through the canonical problem of an elastically mounted, rigid cylinder immersed in uniform flow. However, in the real physical systems where VIV develop, the oncoming flows are usually non-uniform. The present work investigates the impact of a shear of the oncoming current in the cross-flow direction. As a first preliminary step, focus is placed on the fixed cylinder case; the analysis is based on a series of numerical simulations over a wide range of shear rates, at Reynolds number 100. It is found that the shear leads to the cancellation of wake unsteadiness beyond a critical value of the shear rate. Once the rigid cylinder is elastically mounted, free vibrations arise over the entire range of shear rates under study, including beyond the above mentioned critical value. Different flow-structure interaction regimes are uncovered. Some of them exhibit a major deviation from the uniform-flow case, with a profound reconfiguration of the wake patterns and a dramatic amplification of the structural response amplitudes.

  19. Hummingbird feather sounds are produced by aeroelastic flutter, not vortex-induced vibration.

    Science.gov (United States)

    Clark, Christopher J; Elias, Damian O; Prum, Richard O

    2013-09-15

    Males in the 'bee' hummingbird clade produce distinctive, species-specific sounds with fluttering tail feathers during courtship displays. Flutter may be the result of vortex shedding or aeroelastic interactions. We investigated the underlying mechanics of flutter and sound production of a series of different feathers in a wind tunnel. All feathers tested were capable of fluttering at frequencies varying from 0.3 to 10 kHz. At low airspeeds (Uair) feather flutter was highly damped, but at a threshold airspeed (U*) the feathers abruptly entered a limit-cycle vibration and produced sound. Loudness increased with airspeed in most but not all feathers. Reduced frequency of flutter varied by an order of magnitude, and declined with increasing Uair in all feathers. This, along with the presence of strong harmonics, multiple modes of flutter and several other non-linear effects indicates that flutter is not simply a vortex-induced vibration, and that the accompanying sounds are not vortex whistles. Flutter is instead aeroelastic, in which structural (inertial/elastic) properties of the feather interact variably with aerodynamic forces, producing diverse acoustic results.

  20. Design and experiment of controlled bistable vortex induced vibration energy harvesting systems operating in chaotic regions

    Science.gov (United States)

    Huynh, B. H.; Tjahjowidodo, T.; Zhong, Z.-W.; Wang, Y.; Srikanth, N.

    2018-01-01

    Vortex induced vibration based energy harvesting systems have gained interests in these recent years due to its potential as a low water current energy source. However, the effectiveness of the system is limited only at a certain water current due to the resonance principle that governs the concept. In order to extend the working range, a bistable spring to support the structure is introduced on the system. The improvement on the performance is essentially dependent on the bistable gap as one of the main parameters of the nonlinear spring. A sufficiently large bistable gap will result in a significant performance improvement. Unfortunately, a large bistable gap might also increase a chance of chaotic responses, which in turn will result in diminutive harvested power. To mitigate the problem, an appropriate control structure is required to stabilize the chaotic vibrations of a VIV energy converter with the bistable supporting structure. Based on the nature of the double-well potential energy in a bistable spring, the ideal control structure will attempt to drive the responses to inter-well periodic vibrations in order to maximize the harvested power. In this paper, the OGY control algorithm is designed and implemented to the system. The control strategy is selected since it requires only a small perturbation in a structural parameter to execute the control effort, thus, minimum power is needed to drive the control input. Facilitated by a wake oscillator model, the bistable VIV system is modelled as a 4-dimensional autonomous continuous-time dynamical system. To implement the controller strategy, the system is discretized at a period estimated from the subspace hyperplane intersecting to the chaotic trajectory, whereas the fixed points that correspond to the desired periodic orbits are estimated by the recurrence method. Simultaneously, the Jacobian and sensitivity matrices are estimated by the least square regression method. Based on the defined fixed point and the

  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. 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.

  3. Identification of genes induced by salt stress from Medicago ...

    African Journals Online (AJOL)

    In order to identify genes induced during the salt stress response in barrel medic (Medicago truncatula L) seedlings, a cDNA library by salt stress was constructed by suppression subtractive hybridization (SSH). Total RNA from 15-day-old seedlings was used as a 'driver', and total RNA from seedlings induced by salt was ...

  4. Stress, stress?induced cortisol responses, and eyewitness identification performance

    OpenAIRE

    Sauerland, Melanie; Raymaekers, Linsey H.C.; Otgaar, Henry; Memon, Amina; Waltjen, Thijs T.; Nivo, Maud; Slegers, Chiel; Broers, Nick J; Smeets, Tom

    2016-01-01

    Abstract In the eyewitness identification literature, stress and arousal at the time of encoding are considered to adversely influence identification performance. This assumption is in contrast with findings from the neurobiology field of learning and memory, showing that stress and stress hormones are critically involved in forming enduring memories. This discrepancy may be related to methodological differences between the two fields of research, such as the tendency for immediate testing or...

  5. Orientation of bluff body for designing efficient energy harvesters from vortex-induced vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Dai, H. L. [Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Abdelkefi, A. [Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Yang, Y., E-mail: cywyang@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, L. [Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-02-01

    The characteristics and performances of four distinct vortex-induced vibrations (VIVs) piezoelectric energy harvesters are experimentally investigated and compared. The difference between these VIV energy harvesters is the installation of the cylindrical bluff body at the tip of cantilever beam with different orientations (bottom, top, horizontal, and vertical). Experiments show that the synchronization regions of the bottom, top, and horizontal configurations are almost the same at low wind speeds (around 1.5 m/s). The vertical configuration has the highest wind speed for synchronization (around 3.5 m/s) with the largest harvested power, which is explained by its highest natural frequency and the smallest coupled damping. The results lead to the conclusion that to design efficient VIV energy harvesters, the bluff body should be aligned with the beam for low wind speeds (<2 m/s) and perpendicular to the beam at high wind speeds (>2 m/s)

  6. CFD simulation of flow-induced vibration of an elastically supported airfoil

    Science.gov (United States)

    Šidlof, Petr

    2016-03-01

    Flow-induced vibration of lifting or control surfaces in aircraft may lead to catastrophic consequences. Under certain circumstances, the interaction between the airflow and the elastic structure may lead to instability with energy transferred from the airflow to the structure and with exponentially increasing amplitudes of the structure. In the current work, a CFD simulation of an elastically supported NACA0015 airfoil with two degrees of freedom (pitch and plunge) coupled with 2D incompressible airflow is presented. The geometry of the airfoil, mass, moment of inertia, location of the centroid, linear and torsional stiffness was matched to properties of a physical airfoil model used for wind-tunnel measurements. The simulations were run within the OpenFOAM computational package. The results of the CFD simulations were compared with the experimental data.

  7. CFD simulation of flow-induced vibration of an elastically supported airfoil

    Directory of Open Access Journals (Sweden)

    Šidlof Petr

    2016-01-01

    Full Text Available Flow-induced vibration of lifting or control surfaces in aircraft may lead to catastrophic consequences. Under certain circumstances, the interaction between the airflow and the elastic structure may lead to instability with energy transferred from the airflow to the structure and with exponentially increasing amplitudes of the structure. In the current work, a CFD simulation of an elastically supported NACA0015 airfoil with two degrees of freedom (pitch and plunge coupled with 2D incompressible airflow is presented. The geometry of the airfoil, mass, moment of inertia, location of the centroid, linear and torsional stiffness was matched to properties of a physical airfoil model used for wind-tunnel measurements. The simulations were run within the OpenFOAM computational package. The results of the CFD simulations were compared with the experimental data.

  8. Research and design of underwater flow-induced vibration energy harvester based on Karman vortex street

    Science.gov (United States)

    Yao, Gang; Wang, Hai; Yang, Chunlai; Wen, Li

    2017-03-01

    With the increasing development of wireless sensor network (WSN), power supply for WSN nodes had attracted increasing attention, and the energy harvesting system based on Karman vortex street has been widely used in underwater WSN. But the research of the influences of affecting factors towards the energy harvesting system is yet to be completed. So, in this paper, an underwater flow-induced vibration energy harvesting system based on Karman vortex street was proposed and tested. The influence of bluff body geometry and flow velocity towards the performance of the energy harvesting has been researched. The results showed that the output voltage increased as the diameter of bluff body and the water velocity increase. The power generation efficiency was the best when the shape of bluff body was circular.

  9. Estimation of the effects of rain-wind induced vibration in the design stage of inclined stay cables

    NARCIS (Netherlands)

    Geurts, C.P.W.; Staalduinen, P.C. van

    1999-01-01

    Rain-wind induced vibration of stay cables is a great concern for the designers of cable stayed bridges. Despite numerous experimental investigations, an accurate quantitative prediction of this effect in the design stage is not feasible without extensive experiments. This paper presents a model to

  10. Oximetry: a new non-invasive method to detect metabolic effects induced by a local application of mechanical vibration

    Science.gov (United States)

    Felici, A.; Trombetta, C.; Abundo, P.; Foti, C.; Rosato, N.

    2012-10-01

    Mechanical vibrations application is increasingly common in clinical practice due to the effectiveness induced by these stimuli on the human body. Local vibration (LV) application allows to apply and act only where needed, focusing the treatment on the selected body segment. An experimental device for LV application was used to generate the vibrations. The aim of this study was to detect and analyze the metabolic effects induced by LV on the brachial bicep muscle by means of an oximeter. This device monitors tissue and muscle oxygenation using NIRS (Near Infrared Spectroscopy) and is able to determine the concentration of haemoglobin and oxygen saturation in the tissue. In a preliminary stage we also investigated the effects induced by LV application, by measuring blood pressure, heart rate, oxygen saturation and temperature. These data confirmed that the effects induced by LV application are actually localized. The results of the measurements obtained using the oximeter during the vibration application, have shown a variation of the concentrations. In particular an increase of oxygenate haemoglobin was shown, probably caused by an increased muscle activity and/or a rise in local temperature detected during the application.

  11. Electron-Induced Vibrational Spectroscopy. A New and Unique Tool To Unravel the Molecular Structure of Polymer Surfaces

    NARCIS (Netherlands)

    Pireaux, J.J.; Gregoire, Ch.; Caudano, R.; Rei Vilar, M.; Brinkhuis, R.; Schouten, A.J.

    1991-01-01

    Among the surface-sensitive spectroscopies used to characterize clean and surface-modified polymers, one technique has rather recently emerged as a very promising complementary tool. High-resolution electron energy loss spectroscopy, or electron-induced vibrational spectroscopy, has potentially all

  12. Concorde noise-induced building vibrations: John F. Kennedy International Airport

    Science.gov (United States)

    Mayes, W. H.; Stephens, D. G.; Deloach, R.; Cawthorn, J. M.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Ward, D. W.; Miller, W. T.

    1978-01-01

    Outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded at eight homesites and a school along with the associated vibration levels in the walls, windows, and floors at these test sites. Limited subjective tests were conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise. Both vibration and rattle were detected subjectively in several houses for some operations of both the Concorde and subsonic aircraft. Seated subjects more readily detected floor vibrations than wall or window vibrations. Aircraft noise generally caused more window vibrations than common nonaircraft events such as walking and closing doors. Nonaircraft events and aircraft flyovers resulted in comparable wall vibration levels, while floor vibrations were generally greater for nonaircraft events than for aircraft flyovers. The relationship between structural vibration and aircraft noise is linear, with vibration levels being accurately predicted from overall sound pressure levels (OASPL) measured near the structure. Relatively high levels of structural vibration measured during Concorde operations are due more to higher OASPL levels than to unique Concorde-source characteristics.

  13. Pre-dive Whole-Body Vibration Better Reduces Decompression-Induced Vascular Gas Emboli than Oxygenation or a Combination of Both

    Science.gov (United States)

    Balestra, Costantino; Theunissen, Sigrid; Papadopoulou, Virginie; Le Mener, Cedric; Germonpré, Peter; Guerrero, François; Lafère, Pierre

    2016-01-01

    Purpose: Since non-provocative dive profiles are no guarantor of protection against decompression sickness, novel means including pre-dive “preconditioning” interventions, are proposed for its prevention. This study investigated and compared the effect of pre-dive oxygenation, pre-dive whole body vibration or a combination of both on post-dive bubble formation. Methods: Six healthy volunteers performed 6 no-decompression dives each, to a depth of 33 mfw for 20 min (3 control dives without preconditioning and 1 of each preconditioning protocol) with a minimum interval of 1 week between each dive. Post-dive bubbles were counted in the precordium by two-dimensional echocardiography, 30 and 90 min after the dive, with and without knee flexing. Each diver served as his own control. Results: Vascular gas emboli (VGE) were systematically observed before and after knee flexing at each post-dive measurement. Compared to the control dives, we observed a decrease in VGE count of 23.8 ± 7.4% after oxygen breathing (p < 0.05), 84.1 ± 5.6% after vibration (p < 0.001), and 55.1 ± 9.6% after vibration combined with oxygen (p < 0.001). The difference between all preconditioning methods was statistically significant. Conclusions: The precise mechanism that induces the decrease in post-dive VGE and thus makes the diver more resistant to decompression stress is still not known. However, it seems that a pre-dive mechanical reduction of existing gas nuclei might best explain the beneficial effects of this strategy. The apparent non-synergic effect of oxygen and vibration has probably to be understood because of different mechanisms involved. PMID:27965591

  14. Hand-arm vibration syndrome and dose-response relation for vibration induced white finger among quarry drillers and stonecarvers. Italian Study Group on Physical Hazards in the Stone Industry.

    Science.gov (United States)

    Bovenzi, M

    1994-09-01

    To investigate the occurrence of disorders associated with the hand arm vibration syndrome in a large population of stone workers in Italy. The dose-response relation for vibration induced white finger (VWF) was also studied. The study population consisted of 570 quarry drillers and stonecarvers exposed to vibration and 258 control stone workers who performed only manual activity. Each subject was interviewed with health and workplace assessment questionnaires. Sensorineural and VWF disorders were staged according to the Stockholm workshop scales. Vibration was measured on a representative sample of percussive and rotary tools. The 8 h energy equivalent frequency weighted acceleration (A (8)) and lifetime vibration doses were calculated for each of the exposed stone workers. Sensorineural and musculoskeletal symptoms occurred more frequently in the workers exposed to vibration than in the controls, but trend statistics did not show a linear exposure-response relation for these disorders. The prevalence of VWF was found to be 30.2% in the entire group exposed to vibration. Raynaud's phenomenon was discovered in 4.3% of the controls. VWF was strongly associated with exposure to vibration and a monotonic dose-response relation was found. According to the exposure data of this study, the expected percentage of stone workers affected with VWF tends to increase roughly in proportion to the square root of A(8) (for a particular exposure period) or in proportion to the square root of the duration of exposure (for a constant magnitude of vibration). Even although limited to a specific work situation, the dose-response relation for VWF estimated in this study suggests a time dependency such that halving the years of exposure allows a doubling of the energy equivalent vibration. According to these findings, the vibration exposure levels currently under discussion within the European Community seem to represent reasonable exposure limits for the protection of workers against

  15. Application of Vortex Induced Vibration Energy Generation Technologies to the Offshore Oil and Gas Platform: The Preliminary Study

    OpenAIRE

    M. A. Zahari; S. S. Dol

    2014-01-01

    The global demand for continuous and eco-friendly renewable energy as alternative to fossils fuels is large and ever growing in nowadays. This paper will focus on capability of Vortex Induced Vibration (VIV) phenomenon in generating alternative energy for offshore platform application. In order to maximize the potential of energy generation, the effects of lock in phenomenon and different geometries of cylinder were studied in this project. VIV is the motion induced on bl...

  16. Whole Body Vibration Improves Insulin Resistance in db/db Mice: Amelioration of Lipid Accumulation and Oxidative Stress.

    Science.gov (United States)

    Liu, Ying; Zhai, Mingming; Guo, Fan; Shi, Tengrui; Liu, Jiangzheng; Wang, Xin; Zhang, Xiaodi; Jing, Da; Hai, Chunxu

    2016-07-01

    Insulin resistance (IR) is the hallmark of type 2 diabetes mellitus (T2DM), which is one of the most important chronic noncommunicable diseases. Effective and feasible strategies to treat IR are still urgently needed. Previous research studies reported that whole body vibration (WBV) was beneficial for IR in clinical; however, its underlying mechanisms remains unknown. In the present study, db/db mice were treated with WBV administration 60 min/day for 12 weeks and the impaired insulin sensitivity was improved. Besides, liver steatosis was also ameliorated. Further explorations revealed that WBV could reduce the expression of SREBP1c and increase the expression of GSH-Px and consequently suppress oxidative stress. In conclusion, WBV attenuates oxidative stress to ameliorate liver steatosis and thus improves insulin resistance in db/db mice. Therefore, WBV administration is a promising treatment for individuals who suffered from central obesity and IR.

  17. Forming the stress state of a vibroisolated building in the process of mounting rubber steel vibration isolator

    Directory of Open Access Journals (Sweden)

    Dashevskiy Mikhail Aronovich

    2015-12-01

    Full Text Available The necessity to specificate the formation process of stress-strain state of buildings in the construction process is a new problem which requires including real production characteristics going beyond calculation models into calculation methods. Today the construction process lacks this specification. When mounting vibroisolators the stress-strein of a structure state is changing. The mounting method of vibroisolators is patented and consists in multistage successive compression loading of each vibroisolator with the constant speed and following fixation of this displacement. The specified engineering method of rubber-steel pads calculation in view of change of their form during deformation, nonlinearity, rheological processes is offered. Resilient pads look like rubber plates rectangular in plane reinforced on the basic surfaces with metal sheets. The influence of a time-variable static load and free vibrations of loaded pads are considered.

  18. Prototype observation and influencing factors of environmental vibration induced by flood discharge

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2017-01-01

    Full Text Available Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5–3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.

  19. The Vibration Analysis of Tube Bundles Induced by Fluid Elastic Excitation in Shell Side of Heat Exchanger

    Science.gov (United States)

    Bao, Minle; Wang, Lu; Li, Wenyao; Gao, Tianze

    2017-09-01

    Fluid elastic excitation in shell side of heat exchanger was deduced theoretically in this paper. Model foundation was completed by using Pro / Engineer software. The finite element model was constructed and imported into the FLUENT module. The flow field simulation adopted the dynamic mesh model, RNG k-ε model and no-slip boundary conditions. Analysing different positions vibration of tube bundles by selecting three regions in shell side of heat exchanger. The results show that heat exchanger tube bundles at the inlet of the shell side are more likely to be failure due to fluid induced vibration.

  20. Subcooled boiling-induced vibration of a heater rod located between two metallic walls

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Kenji, E-mail: kenji_takano@mhi.co.jp; Hashimoto, Yusuke; Kunugi, Tomoaki; Yokomine, Takehiko; Kawara, Zensaku

    2016-11-15

    Highlights: • A heating structure in water vibrates itself due to subcooled boiling (SBIV). • Experiments with a heater rod located between two metallic walls were conducted. • Large bubbles growing in 1 mm-gap distance with each wall influenced on the SBIV. • Frequency of large bubble generation corresponded to acceleration of the heater rod. • Acceleration of the heater rod in the direction towards each wall was encouraged. - Abstract: The phenomenon that a heating structure vibrates itself due to the behavior of vapor bubbles generated under subcooled boiling has been known as “Subcooled Boiling-induced Vibration (SBIV)”. As one of such a heating structure, fuel assemblies for Boiling Water Reactors (BWR) are utilized in subcooled boiling of water, and those for Pressurized Water Reactors (PWR) may face unexpected subcooled boiling conditions in case of sudden drop of the system pressure or loss of water flow, though they are utilized in single phase of water under normal operating conditions. As studies on SBIV, some researchers have conducted demonstrative experiments with a partial array of fuel rods simulating the actual BWR fuel assembly in a flow test loop, which showed no significant influences of the SBIV to degrade the integrity of the fuel rods. In addition, in order to investigate the fundamental phenomenon of the SBIV, pool boiling experiments of the SBIV on a single heater rod were performed in other studies with a simplified apparatus of a water tank in laboratory size under atmospheric pressure. In the experiments, behavior of bubbles generated under various degree of subcooling were observed, and the acceleration of the SBIV of the heater rod was measured. The present study, as a series of the above experiments for the fundamental phenomenon of the SBIV, the two thin walls made of stainless steel were installed in parallel to interleave the heater rod with the gap distance of 1 mm or 3 mm to each of the two walls, which was expected

  1. Experimentally Induced Stress Validated by EMG Activity

    Science.gov (United States)

    Luijcks, Rosan; Hermens, Hermie J.; Bodar, Lonneke; Vossen, Catherine J.; Os, Jim van.; Lousberg, Richel

    2014-01-01

    Experience of stress may lead to increased electromyography (EMG) activity in specific muscles compared to a non-stressful situation. The main aim of this study was to develop and validate a stress-EMG paradigm in which a single uncontrollable and unpredictable nociceptive stimulus was presented. EMG activity of the trapezius muscles was the response of interest. In addition to linear time effects, non-linear EMG time courses were also examined. Taking into account the hierarchical structure of the dataset, a multilevel random regression model was applied. The stress paradigm, executed in N = 70 subjects, consisted of a 3-minute baseline measurement, a 3-minute pre-stimulus stress period and a 2-minute post-stimulus phase. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. EMG activity during the entire experiment was conform a priori expectations: the pre-stimulus phase showed a significantly higher mean EMG activity level compared to the other two phases, and an immediate EMG response to the stimulus was demonstrated. In addition, the analyses revealed significant non-linear EMG time courses in all three phases. Linear and quadratic EMG time courses were significantly modified by subjective anticipatory stress level, measured just before the start of the stress task. Linking subjective anticipatory stress to EMG stress reactivity revealed that subjects with a high anticipatory stress level responded with more EMG activity during the pre-stimulus stress phase, whereas subjects with a low stress level showed an inverse effect. Results suggest that the stress paradigm presented here is a valid test to quantify individual differences in stress susceptibility. Further studies with this paradigm are required to demonstrate its potential use in mechanistic clinical studies. PMID:24736740

  2. Experimentally induced stress validated by EMG activity.

    Science.gov (United States)

    Luijcks, Rosan; Hermens, Hermie J; Bodar, Lonneke; Vossen, Catherine J; Van Os, Jim; Lousberg, Richel

    2014-01-01

    Experience of stress may lead to increased electromyography (EMG) activity in specific muscles compared to a non-stressful situation. The main aim of this study was to develop and validate a stress-EMG paradigm in which a single uncontrollable and unpredictable nociceptive stimulus was presented. EMG activity of the trapezius muscles was the response of interest. In addition to linear time effects, non-linear EMG time courses were also examined. Taking into account the hierarchical structure of the dataset, a multilevel random regression model was applied. The stress paradigm, executed in N = 70 subjects, consisted of a 3-minute baseline measurement, a 3-minute pre-stimulus stress period and a 2-minute post-stimulus phase. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. EMG activity during the entire experiment was conform a priori expectations: the pre-stimulus phase showed a significantly higher mean EMG activity level compared to the other two phases, and an immediate EMG response to the stimulus was demonstrated. In addition, the analyses revealed significant non-linear EMG time courses in all three phases. Linear and quadratic EMG time courses were significantly modified by subjective anticipatory stress level, measured just before the start of the stress task. Linking subjective anticipatory stress to EMG stress reactivity revealed that subjects with a high anticipatory stress level responded with more EMG activity during the pre-stimulus stress phase, whereas subjects with a low stress level showed an inverse effect. Results suggest that the stress paradigm presented here is a valid test to quantify individual differences in stress susceptibility. Further studies with this paradigm are required to demonstrate its potential use in mechanistic clinical studies.

  3. Experimentally induced stress validated by EMG activity.

    Directory of Open Access Journals (Sweden)

    Rosan Luijcks

    Full Text Available Experience of stress may lead to increased electromyography (EMG activity in specific muscles compared to a non-stressful situation. The main aim of this study was to develop and validate a stress-EMG paradigm in which a single uncontrollable and unpredictable nociceptive stimulus was presented. EMG activity of the trapezius muscles was the response of interest. In addition to linear time effects, non-linear EMG time courses were also examined. Taking into account the hierarchical structure of the dataset, a multilevel random regression model was applied. The stress paradigm, executed in N = 70 subjects, consisted of a 3-minute baseline measurement, a 3-minute pre-stimulus stress period and a 2-minute post-stimulus phase. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. EMG activity during the entire experiment was conform a priori expectations: the pre-stimulus phase showed a significantly higher mean EMG activity level compared to the other two phases, and an immediate EMG response to the stimulus was demonstrated. In addition, the analyses revealed significant non-linear EMG time courses in all three phases. Linear and quadratic EMG time courses were significantly modified by subjective anticipatory stress level, measured just before the start of the stress task. Linking subjective anticipatory stress to EMG stress reactivity revealed that subjects with a high anticipatory stress level responded with more EMG activity during the pre-stimulus stress phase, whereas subjects with a low stress level showed an inverse effect. Results suggest that the stress paradigm presented here is a valid test to quantify individual differences in stress susceptibility. Further studies with this paradigm are required to demonstrate its potential use in mechanistic clinical studies.

  4. Glycolaldehyde induces endoplasmic reticulum stress and apoptosis in Schwann cells

    Directory of Open Access Journals (Sweden)

    Keisuke Sato

    2015-01-01

    Full Text Available Schwann cell injury is caused by diabetic neuropathy. The apoptosis of Schwann cells plays a pivotal role in diabetic nerve dysfunction. Glycolaldehyde is a precursor of advanced glycation end products that contribute to the pathogenesis of diabetic neuropathy. In this study, we examined whether glycolaldehyde induces endoplasmic reticulum (ER stress and apoptosis in rat Schwann cells. Schwann cells treated with 500 μM glycolaldehyde showed morphological changes characteristic of apoptosis. Glycolaldehyde activated apoptotic signals, such as caspase-3 and caspase-8. Furthermore, it induced ER stress response involving RNA-dependent protein kinase-like ER kinase (PERK, inositol-requiring ER-to-nucleus signal kinase 1α (IRE1α, and eukaryotic initiation factor 2α (eIF2α. In addition, glycolaldehyde activated CCAAT/enhancer-binding homologous protein (CHOP, an ER stress response factor crucial to executing apoptosis. Knockdown of nuclear factor E2-related factor 2 (Nrf2, which is involved in the promotion of cell survival following ER stress, enhanced glycolaldehyde-induced cytotoxicity, indicating that Nrf2 plays a protective role in the cytotoxicity caused by glycolaldehyde. Taken together, these findings indicate that glycolaldehyde is capable of inducing apoptosis and ER stress in Schwann cells. The ER stress induced by glycolaldehyde may trigger the glycolaldehyde-induced apoptosis in Schwann cells. This study demonstrated for the first time that glycolaldehyde induced ER stress.

  5. A direct pedestrian-structure interaction model to characterize the human induced vibrations on slender footbridges

    Directory of Open Access Journals (Sweden)

    Jiménez-Alonso, J. F.

    2014-12-01

    Full Text Available Although the scientific community had knowledge of the human induced vibration problems in structures since the end of the 19th century, it was not until the occurrence of the vibration phenomenon happened in the Millennium Bridge (London, 2000 that the importance of the problem revealed and a higher level of attention devoted. Despite the large advances achieved in the determination of the human-structure interaction force, one of the main deficiencies of the existing models is the exclusion of the effect of changes in the footbridge dynamic properties due to the presence of pedestrians. In this paper, the formulation of a human-structure interaction model, addresses these limitations, is carried out and its reliability is verified from previously published experimental results.Aunque la comunidad científica tenía conocimiento de los problemas vibratorios inducidos por peatones en estructuras desde finales del siglo xix, no fue hasta la ocurrencia de los eventos vibratorios acontecidos en la pasarela del Milenio (Londres, 2000, cuando la importancia del problema se puso de manifiesto y se le comenzó a dedicar un mayor nivel de atención. A pesar de los grandes avances alcanzados en la caracterización de la fuerza de interacción peatón-estructura una de las principales deficiencias de los modelos existentes es la exclusión del cambio en las propiedades dinámicas de la pasarela por la presencia de peatones. En este artículo, se presenta la formulación de un modelo de interacción peatón-estructura que intenta dar respuesta a dichas limitaciones, y su validación a partir de resultados experimentales previamente publicados por otros autores.

  6. Vortex-induced vibrations of three staggered circular cylinders at low Reynolds numbers

    Science.gov (United States)

    Behara, Suresh; Ravikanth, B.; Chandra, Venu

    2017-08-01

    Vortex-induced vibrations of three staggered circular cylinders are investigated via two-dimensional finite element computations. All the cylinders are of equal diameter (D) and are mounted on elastic supports in both streamwise (x -) and transverse (y -) directions. The two downstream cylinders are placed symmetrically on either side of the upstream body at a streamwise gap of 5D, with the vertical distance between them being 3D. Flow simulations are carried out for Reynolds numbers (Re) in the range of Re = 60-160. Reduced mass (m*) of 10 is considered and the damping is set to zero value. The present investigations show that the upstream cylinder exhibits initial and lower synchronization response modes like an isolated cylinder does at low Re. Whereas for both the downstream cylinders, the upper lock-in branch also appears. The initial and the upper modes are characterized by periodic oscillations, while the lower lock-in branch is associated with nonperiodic vibrations. The 2S mode of vortex shedding is observed in the near wake of all the cylinders for all Re, except for the upper branch corresponding to the downstream bodies. In the upper branch, both the downstream cylinders shed the primary vortices of the P+S mode. For the upstream cylinder, the phase between lift and the transverse displacement exhibits a 18 0° jump at certain Re in the lower branch. On the other hand, the downstream bodies undergo transverse oscillations in phase with lift in all lock-in modes, while the phase jumps by 18 0° as the oscillation response reaches the desynchronization regime.

  7. Inspection of arterial-induced skin vibration by Moire fringe with two-dimensional continuous wavelet transform

    Science.gov (United States)

    Wang, Chun-Hsiung; Chiu, Shih-Yung; Hsu, Yu-Hsiang; Lee, Shu-Sheng; Lee, Chih-Kung

    2017-06-01

    A non-contact arterial-induced skin vibration inspection system is implemented. This optical metrology system is constructed with shadow Moiré configuration and the fringe analysis algorithm. Developed with the Region of Interested (ROI) capturing technique and the Two-dimensional Wavelet Transform (2D-CWT) method, this algorithm is able to retrieve the height-correlated phase information from the shadow Moiré fringe patterns. Using a commercial video camera or a CMOS image sensor, this system could monitor the skin-vibration induced by the cyclic deformation of inner layered artery. The cross-sectional variation and the rhythm of heart cycle could be continuously measured for health monitoring purposes. The average vibration amplitude of the artery at the wrist ranges between 20 μm and 50 μm, which is quite subtle comparing with the skin surface structure. Having the non-stationary motion of human body, the traditional phase shifting (PS) technique can be very unstable due to the requirement of several frames of images, especially for case that artery is continuously pumping. To bypass this fundamental issue, the shadow Moiré technique is introduced to enhance the surface deformation characteristic. And the phase information is retrieved by the means of spectrum filtering instead of PS technique, which the phase is calculated from intensity maps of multiple images. The instantaneous surface can therefore be reconstructed individually from each frame, enabling the subtle arterial-induced skin vibration measurement. The comparative results of phase reconstruction between different fringe analysis algorithms will be demonstrated numerically and experimentally. And the electrocardiography (ECG) results will used as the reference for the validity of health monitoring potential of the non-contact arterial-induced skin vibration inspection system.

  8. Stress, stress-induced cortisol responses, and eyewitness identification performance.

    Science.gov (United States)

    Sauerland, Melanie; Raymaekers, Linsey H C; Otgaar, Henry; Memon, Amina; Waltjen, Thijs T; Nivo, Maud; Slegers, Chiel; Broers, Nick J; Smeets, Tom

    2016-07-01

    In the eyewitness identification literature, stress and arousal at the time of encoding are considered to adversely influence identification performance. This assumption is in contrast with findings from the neurobiology field of learning and memory, showing that stress and stress hormones are critically involved in forming enduring memories. This discrepancy may be related to methodological differences between the two fields of research, such as the tendency for immediate testing or the use of very short (1-2 hours) retention intervals in eyewitness research, while neurobiology studies insert at least 24 hours. Other differences refer to the extent to which stress-responsive systems (i.e., the hypothalamic-pituitary-adrenal axis) are stimulated effectively under laboratory conditions. The aim of the current study was to conduct an experiment that accounts for the contemporary state of knowledge in both fields. In all, 123 participants witnessed a live staged theft while being exposed to a laboratory stressor that reliably elicits autonomic and glucocorticoid stress responses or while performing a control task. Salivary cortisol levels were measured to control for the effectiveness of the stress induction. One week later, participants attempted to identify the thief from target-present and target-absent line-ups. According to regression and receiver operating characteristic analyses, stress did not have robust detrimental effects on identification performance. Copyright © 2016 John Wiley & Sons, Ltd. © 2016 The Authors Behavioral Sciences & the Law Published by John Wiley & Sons Ltd. © 2016 The Authors Behavioral Sciences & the Law Published by John Wiley & Sons Ltd.

  9. Investigations on the Effects of Vortex-Induced Vibration with Different Distributions of Lorentz Forces

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2017-01-01

    Full Text Available The control of vortex-induced vibration (VIV in shear flow with different distributions of Lorentz force is numerically investigated based on the stream function–vorticity equations in the exponential-polar coordinates exerted on moving cylinder for Re = 150. The cylinder motion equation coupled with the fluid, including the mathematical expressions of the lift force coefficient C l , is derived. The initial and boundary conditions as well as the hydrodynamic forces on the surface of cylinder are also formulated. The Lorentz force applied to suppress the VIV has no relationship with the flow field, and involves two categories, i.e., the field Lorentz force and the wall Lorentz force. With the application of symmetrical Lorentz forces, the symmetric field Lorentz force can amplify the drag, suppress the flow separation, decrease the lift fluctuation, and then suppress the VIV while the wall Lorentz force decreases the drag only. With the application of asymmetrical Lorentz forces, besides the above-mentioned effects, the field Lorentz force can increase additional lift induced by shear flow, whereas the wall Lorentz force can counteract the additional lift, which is dominated on the total effect.

  10. Vortex-Induced Vibration of an Airfoil Used in Vertical-Axis Wind Turbines

    Science.gov (United States)

    Benner, Bridget; Carlson, Daniel; Seyed-Aghazadeh, Banafsheh; Modarres-Sadeghi, Yahya

    2017-11-01

    In Vertical-axis wind turbines (VAWTs), when the blades are placed at high angles of attack with respect to the incoming flow, they could experience flow-induced oscillations. A series of experiments in a re-circulating water tunnel was conducted to study the possible Vortex-Induced Vibration (VIV) of a fully-submerged, flexibly-mounted NACA 0021 airfoil, which is used in some designs of VAWTs. The airfoil was free to oscillate in the crossflow direction, and the tests were conducted in a Reynolds number range of 600

  11. Buzz pollination in eight bumblebee-pollinated Pedicularis species: does it involve vibration-induced triboelectric charging of pollen grains?

    Science.gov (United States)

    Corbet, Sarah A; Huang, Shuang-Quan

    2014-12-01

    Buzz pollination involves explosive pollen release in response to vibration, usually by bees. The mechanism of pollen release is poorly understood, and it is not clear which component of vibration (acceleration, frequency, displacement or velocity) is critical; the role of buzz frequency has been particularly controversial. This study proposes a novel hypothesis that explosive pollen release results from vibration-induced triboelectric charging. If it does, pollen release is expected to depend on achievement of a critical threshold velocity. Eight sympatric buzz-pollinated species of Pedicularis that share bumblebee pollinator species were studied, giving a rare opportunity to compare sonication behaviour of a shared pollinator on different plant species. Reconsidering previous experimental studies, it is argued that they establish the critical role of the velocity component of vibration in pollen release, and that when displacement is constrained by body size bees can achieve the critical velocity by adjusting frequency. It was shown that workers of Bombus friseanus assorted themselves among Pedicularis species by body size, and that bees adjusted their buzz/wingbeat frequency ratio, which is taken as an index of the velocity component, to a value that corresponds with the galea length and pollen grain volume of each species of Pedicularis. Sonication behaviour of B. friseanus differs among Pedicularis species, not only because worker bees assort themselves among plant species by body size, but also because bees of a given size adjust the buzz frequency to achieve a vibration velocity corresponding to the floral traits of each plant species. These findings, and the floral traits that characterize these and other buzz-pollinated species, are compatible with the hypothesis of vibration-induced triboelectric charging of pollen grains. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For

  12. Concorde noise-induced building vibrations, John F. Kennedy International Airport

    Science.gov (United States)

    Mayes, W. H.; Deloach, R.; Stephens, D. G.; Cawthorn, J. M.; Holmes, H. K.; Lewis, R. B.; Holliday, B. G.; Miller, W. T.; Ward, D. W.

    1978-01-01

    The outdoor/indoor noise levels and associated vibration levels resulting from aircraft and nonaircraft events were recorded at eight homesites and a school. In addition, limited subjective tests were conducted to examine the human detection/annoyance thresholds for building vibration and rattle caused by aircraft noise. Presented herein are the majority of the window and wall vibration data recorded during Concorde and subsonic aircraft overflights.

  13. Pesticide-induced oxidative stress: perspectives and trends.

    Science.gov (United States)

    Banerjee, B D; Seth, V; Ahmed, R S

    2001-01-01

    Pesticide-induced oxidative stress as a possible mechanism of toxicity has been a focus of toxicological research for the last decade. Yet for certain pesticides, mechanisms leading to oxidative stress are only partly understood. Pesticide-induced oxidative stress is the final manifestation of a multi-step pathway, resulting in an imbalance between pro-oxidant and antioxidant defense mechanisms. Concomitantly, pesticide intoxication induces a derangement of certain antioxidant mechanisms in different tissues, including alterations in antioxidant enzymes and the glutathione redox system. In this article, we discuss the impact of certain factors that are important in the potentiation of pesticide-induced oxidative stress, immunotoxicity, and apoptosis. Understanding risk factors largely depends upon the cellular and molecular events underlying pesticide-induced stress in experimental animals. These factors must be considered in the safety/toxicity evaluation of any pesticide. The identification and characterization of plant products/drugs might be helpful for understanding the mechanisms of compensation and repair that are due to oxidative stress-induced injury. This paper reviews the nature of such damage, the cellular conditions in which it occurs, and oxidative-stress data that may be applied to the development of risk-assessment methods and models that are designed to reduce some of these uncertainties.

  14. Salubrious effects of oxytocin on social stress-induced deficits.

    Science.gov (United States)

    Smith, Adam S; Wang, Zuoxin

    2012-03-01

    Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While positive social interactions can attenuate stress and promote health, the social environment can also be a major source of stress when it includes social disruption, confrontation, isolation, or neglect. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to mental and physical health. In contrast, social support can ameliorate stress-induced physiological and immunological deficits, reducing the risk of subsequent psychological distress and improving an individual's overall well-being. For better clinical treatment of these physiological and mental pathologies, it is necessary to understand the regulatory mechanisms of stress-induced pathologies as well as determine the underlying biological mechanisms that regulate social buffering of the stress system. A number of ethologically relevant animal models of social stress and species that form strong adult social bonds have been utilized to study the etiology, treatment, and prevention of stress-related disorders. While undoubtedly a number of biological pathways contribute to the social buffering of the stress response, the convergence of evidence denotes the regulatory effects of oxytocin in facilitating social bond-promoting behaviors and their effect on the stress response. Thus, oxytocin may be perceived as a common regulatory element of the social environment, stress response, and stress-induced risks on mental and physical health. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior. Published by Elsevier Inc.

  15. Stress-Induced Cortisol Hampers Memory Generalization

    Science.gov (United States)

    Dandolo, Lisa C.; Schwabe, Lars

    2016-01-01

    Integrative encoding and generalization across past experiences depends largely on the hippocampus, an area known to be particularly sensitive to stress. Yet, whether stress influences the ability to generalize memories is unknown. We exposed volunteers to a stressor or a control manipulation before they completed an acquired equivalence task…

  16. Experimental study on flow-induced vibration of propeller blades under non-uniform inflow

    Directory of Open Access Journals (Sweden)

    LI Jing

    2017-12-01

    Full Text Available [Objectives] This article presents an experimental study of the flow-induced vibration of propeller blades under periodic inflow, and the dependence of the response on its modes.[Methods] Two seven-bladed highly skewed model propellers of identical proportions but different material are operated in four-cycle and six-cycle inflows to produce a blade vibratory strain response. Two kinds of wire mesh wake screens located 400 mm upstream of the propeller plane are used to generate the four-cycle and six-cycle inflows. A laser Doppler velocimetry system located 100 mm downstream of the wake screen plane is used to measure the axial velocity distributions produced by the wake screens. Strain gauges are attached to the propeller blades at different positions. The data from the strain gauges quantifies the excitation frequencies induced by the wake screens. It is shown that the response will reach peak axial propeller frequency, four times axial propeller frequency and six times axial propeller frequency under uniform inflow, four-cycle inflow and six-cycle inflow respectively.[Results] The effect of resonance on the vibratory strain response is revealed. When six times axial propeller frequency induced by six-cycle inflow coincides with the natural frequency of a flexible propeller, the response of the propeller is at its greatest.[Conclusions] This research reveals that when designing a propeller, it is not sufficient to only focus on its hydrodynamic properties; the effects of the modes of the propeller should also be considered.

  17. The Yeast Environmental Stress Response Regulates Mutagenesis Induced by Proteotoxic Stress

    Science.gov (United States)

    Shor, Erika; Fox, Catherine A.; Broach, James R.

    2013-01-01

    Conditions of chronic stress are associated with genetic instability in many organisms, but the roles of stress responses in mutagenesis have so far been elucidated only in bacteria. Here, we present data demonstrating that the environmental stress response (ESR) in yeast functions in mutagenesis induced by proteotoxic stress. We show that the drug canavanine causes proteotoxic stress, activates the ESR, and induces mutagenesis at several loci in an ESR-dependent manner. Canavanine-induced mutagenesis also involves translesion DNA polymerases Rev1 and Polζ and non-homologous end joining factor Ku. Furthermore, under conditions of chronic sub-lethal canavanine stress, deletions of Rev1, Polζ, and Ku-encoding genes exhibit genetic interactions with ESR mutants indicative of ESR regulating these mutagenic DNA repair processes. Analyses of mutagenesis induced by several different stresses showed that the ESR specifically modulates mutagenesis induced by proteotoxic stress. Together, these results document the first known example of an involvement of a eukaryotic stress response pathway in mutagenesis and have important implications for mechanisms of evolution, carcinogenesis, and emergence of drug-resistant pathogens and chemotherapy-resistant tumors. PMID:23935537

  18. The yeast environmental stress response regulates mutagenesis induced by proteotoxic stress.

    Directory of Open Access Journals (Sweden)

    Erika Shor

    Full Text Available Conditions of chronic stress are associated with genetic instability in many organisms, but the roles of stress responses in mutagenesis have so far been elucidated only in bacteria. Here, we present data demonstrating that the environmental stress response (ESR in yeast functions in mutagenesis induced by proteotoxic stress. We show that the drug canavanine causes proteotoxic stress, activates the ESR, and induces mutagenesis at several loci in an ESR-dependent manner. Canavanine-induced mutagenesis also involves translesion DNA polymerases Rev1 and Polζ and non-homologous end joining factor Ku. Furthermore, under conditions of chronic sub-lethal canavanine stress, deletions of Rev1, Polζ, and Ku-encoding genes exhibit genetic interactions with ESR mutants indicative of ESR regulating these mutagenic DNA repair processes. Analyses of mutagenesis induced by several different stresses showed that the ESR specifically modulates mutagenesis induced by proteotoxic stress. Together, these results document the first known example of an involvement of a eukaryotic stress response pathway in mutagenesis and have important implications for mechanisms of evolution, carcinogenesis, and emergence of drug-resistant pathogens and chemotherapy-resistant tumors.

  19. Possible Biomarkers of Chronic Stress Induced Exhaustion - A Longitudinal Study.

    Science.gov (United States)

    Wallensten, Johanna; Åsberg, Marie; Nygren, Åke; Szulkin, Robert; Wallén, Håkan; Mobarrez, Fariborz; Nager, Anna

    2016-01-01

    Vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and monocyte chemotactic protein-1 (MCP-1) have previously been suggested to be potential biomarkers for chronic stress induced exhaustion. The knowledge about VEGF has increased during the last decades and supports the contention that VEGF plays an important role in stress and depression. There is scarce knowledge on the possible relationship of EGF and MCP-1 in chronic stress and depression. This study further examines the role of VEGF, EGF and MCP-1 in women with chronic stress induced exhaustion and healthy women during a follow-up period of two years. Blood samples were collected from 105 women with chronic stress induced exhaustion on at least 50% sick leave for at least three months, at inclusion (T0), after 12 months (T12) and after 24 months (T24). Blood samples were collected at inclusion (T0) in 116 physically and psychiatrically healthy women. The plasma levels of VEGF, EGF and MCP-1 were analyzed using Biochip Array Technology. Women with chronic stress induced exhaustion had significantly higher plasma levels of VEGF and EGF compared to healthy women at baseline, T12 and at T24. There was no significant difference in plasma levels of MCP-1. Plasma levels of VEGF and EGF decreased significantly in women with chronic stress induced exhaustion during the two years follow-up. The replicated findings of elevated levels of VEGF and EGF in women with chronic stress induced exhaustion and decreasing plasma levels of VEGF and EGF during the two years follow-up add important knowledge to the pathophysiology of chronic stress induced exhaustion.

  20. Discussion of "A new method for predicting nonlinear structural vibrations induced by ground impact loading" by Jun Liu, Yu Zhang, Bin Yun, Journal of Sound and Vibration, 331 (2012) 2129-2140

    Science.gov (United States)

    Svinkin, Mark R.

    2016-12-01

    The authors suggested a hybrid method for modeling the time history of structural vibrations triggered by impact dynamic loads from construction equipment and blasting, and they stated, "In this work, a hybrid method has been proposed to calculate the theoretical seismograms of structural vibrations. The word "hybrid" denotes a combination of field measurements and computer simulations. Then, based on nonlinear system theory, a novel method is proposed to predict the signal induced by impact loading".

  1. 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...

  2. Salubrious effects of oxytocin on social stress-induced deficits

    OpenAIRE

    Adam S. Smith; Wang, Zuoxin

    2011-01-01

    Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While social interactions can attenuate stress and promote health, disruption, confrontations, isolation, or neglect in the social environment can each be major stressors. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to m...

  3. Serotonergic involvement in stress-induced vasopressin and oxytocin secretion

    DEFF Research Database (Denmark)

    Jørgensen, Henrik; Knigge, Ulrich; Kjaer, Andreas

    2002-01-01

    OBJECTIVE: To investigate the involvement of serotonin (5-hydroxytryptamine - 5-HT) receptors in mediation of stress-induced arginine vasopressin (AVP) and oxytocin (OT) secretion in male rats. DESIGN: Experiments on laboratory rats with control groups. METHODS: Different stress paradigms were...

  4. extract on oxidative stress induced by chloroquine in albino rats

    African Journals Online (AJOL)

    This study evaluated the antioxidant and protective effects of Hypoxis hemerocallidea Fisch. & C. A. Mey. (Hypoxidaceae) Corm ('African potato') water extract (HH) against chloroquine induced oxidative stress in albino rats. Chloroquine has been known to generate oxidative stress when used for different types of treatment ...

  5. Emotional Intelligence, Personality, and Task-Induced Stress

    Science.gov (United States)

    Matthews, Gerald; Emo, Amanda K.; Funke, Gregory; Zeidner, Moshe; Roberts, Richard D.; Costa, Paul T.; Schulze, Ralf

    2006-01-01

    Emotional intelligence (EI) may predict stress responses and coping strategies in a variety of applied settings. This study compares EI and the personality factors of the Five Factor Model (FFM) as predictors of task-induced stress responses. Participants (N = 200) were randomly assigned to 1 of 4 task conditions, 3 of which were designed to be…

  6. Water stress induces overexpression of superoxide dismutases that ...

    African Journals Online (AJOL)

    Water stress is known to induce active oxygen species in plants. The accumulation of these harmful species must be prevented by plants as rapidly as possible to maintain growth and productivity. The aim of this study was to determine the effect of water stress on superoxide dismutase isozymes (SOD, EC 1.15.1.1.) in two ...

  7. Serotonergic involvement in stress-induced vasopressin and oxytocin secretion

    DEFF Research Database (Denmark)

    Jørgensen, Henrik; Knigge, Ulrich; Kjaer, Andreas

    2002-01-01

    OBJECTIVE: To investigate the involvement of serotonin (5-hydroxytryptamine - 5-HT) receptors in mediation of stress-induced arginine vasopressin (AVP) and oxytocin (OT) secretion in male rats. DESIGN: Experiments on laboratory rats with control groups. METHODS: Different stress paradigms were ap...

  8. Leader-Member Exchange And Leadership-Induced Stress: When ...

    African Journals Online (AJOL)

    This study examined the extent to which Leader-Member Exchange (LMX) can predict leadership-induced stress (stress that employees experience which they believe is caused by their organizational leaders), and whether and how coworker support intervene in this prediction. A total of 620 junior and middle cadre ...

  9. Altered Gravity Induces Oxidative Stress in Drosophila Melanogaster

    Science.gov (United States)

    Bhattacharya, Sharmila; Hosamani, Ravikumar

    2015-01-01

    Altered gravity environments can induce increased oxidative stress in biological systems. Microarray data from our previous spaceflight experiment (FIT experiment on STS-121) indicated significant changes in the expression of oxidative stress genes in adult fruit flies after spaceflight. Currently, our lab is focused on elucidating the role of hypergravity-induced oxidative stress and its impact on the nervous system in Drosophila melanogaster. Biochemical, molecular, and genetic approaches were combined to study this effect on the ground. Adult flies (2-3 days old) exposed to acute hypergravity (3g, for 1 hour and 2 hours) showed significantly elevated levels of Reactive Oxygen Species (ROS) in fly brains compared to control samples. This data was supported by significant changes in mRNA expression of specific oxidative stress and antioxidant defense related genes. As anticipated, a stress-resistant mutant line, Indy302, was less vulnerable to hypergravity-induced oxidative stress compared to wild-type flies. Survival curves were generated to study the combined effect of hypergravity and pro-oxidant treatment. Interestingly, many of the oxidative stress changes that were measured in flies showed sex specific differences. Collectively, our data demonstrate that altered gravity significantly induces oxidative stress in Drosophila, and that one of the organs where this effect is evident is the brain.

  10. Chlorpyrifos induces endoplasmic reticulum stress in JEG-3 cells.

    Science.gov (United States)

    Reyna, Luciana; Flores-Martín, Jésica; Ridano, Magali E; Panzetta-Dutari, Graciela M; Genti-Raimondi, Susana

    2017-04-01

    Chlorpyrifos (CPF) is an organophosphorous pesticide widely used in agricultural, industrial, and household applications. We have previously shown that JEG-3 cells are able to attenuate the oxidative stress induced by CPF through the adaptive activation of the Nrf2/ARE pathway. Considering that there is a relationship between oxidative stress and endoplasmic reticulum stress (ER), herein we investigated whether CPF also induces ER stress in JEG-3 cells. Cells were exposed to 50μM or 100μM CPF during 24h in conditions where cell viability was not altered. Western blot and PCR assays were used to explore the protein and mRNA levels of ER stress biomarkers, respectively. CPF induced an increase of the typical ER stress-related proteins, such as GRP78/BiP and IRE1α, a sensor for the unfolded protein response, as well as in phospho-eIF2α and XBP1 mRNA splicing. Additionally, CPF led to a decrease in p53 protein expression. The downregulation of p53 levels induced by CPF was partially blocked when cells were exposed to CPF in the presence of the proteasome inhibitor MG132. Altogether, these findings point out that CPF induces ER stress in JEG-3 cells; however these cells are able to attenuate it downregulating the levels of the pro-apoptotic protein p53. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Frequencies in the Vibration Induced by the Rotor Stator Interaction in a Centrifugal Pump Turbine

    DEFF Research Database (Denmark)

    Rodriguez, Cristian; Egusquiza, Eduard; Santos, Ilmar

    2007-01-01

    The highest vibration levels in large pump turbines are, in general, originated in the rotor stator interaction (RSI). This vibration has specific characteristics that can be clearly observed in the frequency domain: harmonics of the moving blade passing frequency and a particular relationship am...

  12. Analysis of muscle fatigue induced by isometric vibration exercise at varying frequencies.

    Science.gov (United States)

    Mischi, M; Rabotti, C; Cardinale, M

    2012-01-01

    An increase in neuromuscular activity, measured by electromyography (EMG), is usually observed during vibration exercise. The underlying mechanisms are however unclear, limiting the possibilities to introduce and exploit vibration training in rehabilitation programs. In this study, a new training device is used to perform vibration exercise at varying frequency and force, therefore enabling the analysis of the relationship between vibration frequency and muscle fatigue. Fatigue is estimated by maximum voluntary contraction measurement, as well as by EMG mean-frequency and conduction-velocity analysis. Seven volunteers performed five isometric contractions of the biceps brachii with a load consisting of a baseline of 80% of their maximum voluntary contraction (MVC), with no vibration and with a superimposed 20, 30, 40, and 50 Hz vibrational force of 40 N. Myoelectric and mechanical fatigue were estimated by EMG analysis and by assessment of the MVC decay, respectively. A dedicated motion artifact canceler, making use of accelerometry, is proposed to enable accurate EMG analysis. Use of this canceler leads to better interpolation of myoelectric fatigue trends and to better correlation between mechanical and myoelectric fatigue. In general, our results suggest vibration at 30 Hz to be the most fatiguing exercise. These results contribute to the analysis of vibration exercise and motivate further research aiming at improved training protocols.

  13. Interfacial stresses in vibration of multilayer composite materials: experimental and theoretical analysis

    Science.gov (United States)

    Agbossou, Amen; Barthod, Christine; Teisseyre, Yves; Gautier, Gérard

    2005-12-01

    In laminated composites, interfaces are the transfer spots of mechanical charges, mechanical over-stress adaptations and energy dissipations. In order to examine the dynamic effects of interface stresses, we have inserted a thin layer of piezoelectric material at the interface of composite plies of a multilayer cantilever beam excited in bending. The voltage signals generated by the piezoelectric elements are seen to be dependent on the expected interlaminar stresses. Moreover, the realized experimental set-up validates the parameters of finite element simulations. Using the implemented finite element model, two different piezoelectric materials are compared with regard to their possibility for interfacial stress measurement and for mechanical energy dissipation.

  14. Potential role of punicalagin against oxidative stress induced testicular damage

    Directory of Open Access Journals (Sweden)

    Faiza Rao

    2016-01-01

    Full Text Available Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98% on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU against oxidative stress-induced infertility. Results demonstrated that 9 mg kg−1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility.

  15. Potential role of punicalagin against oxidative stress induced testicular damage.

    Science.gov (United States)

    Rao, Faiza; Tian, Hui; Li, Wenqing; Hung, Helong; Sun, Fei

    2016-01-01

    Punicalagin is isolated from pomegranate and widely used for the treatment of different diseases in Chinese traditional medicine. This study aimed to evaluate the effect of Punicalagin (purity ≥98%) on oxidative stress induced testicular damage and its effect on fertility. We detected the antioxidant potential of punicalagin in lipopolysaccharide (LPS) induced oxidative stress damage in testes, also tried to uncover the boosting fertility effect of Punicalagin (PU) against oxidative stress-induced infertility. Results demonstrated that 9 mg kg-1 for 7 days treatment significantly decreases LPS induced oxidative damage in testes and nitric oxide production. The administration of oxidative stress resulted in a significant reduction in testes antioxidants GSH, T-SOD, and CAT raised LPO, but treatment with punicalagin for 7 days increased antioxidant defense GSH, T-SOD, and CAT by the end of the experiment and reduced LPO level as well. PU also significantly activates Nrf2, which is involved in regulation of antioxidant defense systems. Hence, the present research categorically elucidates the protective effect of punicalagin against LPS induced oxidative stress induced perturbation in the process of spermatogenesis and significantly increased sperm health and number. Moreover, fertility success significantly decreased in LPS-injected mice compared to controls. Mice injected with LPS had fertility indices of 12.5%, while others treated with a combination of PU + LPS exhibited 75% indices. By promoting fertility and eliminating oxidative stress and inflammation, PU may be a useful nutrient for the treatment of infertility.

  16. Interleukin-6 expression under gravitational stress due to vibration and hypergravity in follicular thyroid cancer cells.

    Science.gov (United States)

    Ma, Xiao; Wehland, Markus; Aleshcheva, Ganna; Hauslage, Jens; Waßer, Kai; Hemmersbach, Ruth; Infanger, Manfred; Bauer, Johann; Grimm, Daniela

    2013-01-01

    It is known that exposing cell lines in vitro to parabolic flights changes their gene expression and protein production patterns. Parabolic flights and spaceflight in general are accompanied by transient hypergravity and vibration, which may impact the cells and therefore, have to be considered too. To estimate the possible impact of transient hypergravity and vibration, we investigated the effects of these forces separately using dedicated ground-based facilities. We placed follicular thyroid ML-1 and CGTH W-1 cancer cells in a specific centrifuge (MuSIC Multi Sample Incubator Centrifuge; SAHC Short Arm Human Centrifuge) simulating the hypergravity phases that occur during one (P1) and 31 parabolas (P31) of parabolic flights, respectively. On the Vibraplex device, the same cell lines were treated with vibration waves corresponding to those that occur during a whole parabolic flight lasting for two hours. After the various treatments, cells were harvested and analyzed by quantitative real-time PCR, focusing on the genes involved in forming (ACTB, MYO9, TUBB, VIM, TLN1, and ITGB1) and modulating (EZR, RDX, and MSN) the cytoskeleton, as well as those encoding growth factors (EGF, CTGF, IL6, and IL8) or protein kinases (PRKAA1 and PRKCA). The analysis revealed alterations in several genes in both cell lines; however, fewer genes were affected in ML-1 than CGTH W-1 cells. Interestingly, IL6 was the only gene whose expression was changed in both cell lines by each treatment, while PKCA transcription remained unaffected in all experiments. We conclude that a PKCa-independent mechanism of IL6 gene activation is very sensitive to physical forces in thyroid cells cultured in vitro as monolayers.

  17. Dynamic characteristics of a cable-stayed bridge measured from traffic-induced vibrations

    Science.gov (United States)

    Wang, Yun-Che; Chen, Chern-Hwa

    2012-09-01

    This paper studies the dynamic characteristics of the Kao-Ping-Hsi cable-stayed bridge under daily traffic conditions. Experimental data were measured from a structural monitoring system, and system-identification techniques, such as the random decrement (RD) technique and Ibrahim time-domain (ITD) method, were adopted. The first five modes of the bridge were identified for their natural frequencies and damping ratios under different traffic loading conditions, in terms of root-mean-square (RMS) deck velocities. The magnitude of the torsion mode of the Kao-Ping-Hsi cable-stayed bridge is found to be one order-of-magnitude less than the transfer mode, and two orders-of-magnitude less than the vertical modes. Out results indicated that vibrations induced by traffic flow can be used as an indicator to monitor the health of the bridge due to their insensitivity to the natural frequencies of the cable-stayed bridge. Furthermore, the damping ratios may be used as a more sensitive indicator to describe the condition of the bridge.

  18. Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

    Directory of Open Access Journals (Sweden)

    Kurian V. J.

    2017-01-01

    Full Text Available Vortex Induced Vibrations (VIV may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP, Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT. VIVFT is a two degree of freedom (2DOF forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes.

  19. Suppression of vortex-induced vibrations in a flexible cylinder with elastic splitter plates

    Science.gov (United States)

    Huera-Huarte, Francisco

    2013-11-01

    Suppression of vortex-induced vibrations (VIV) is a topic that has received a lot of attention due to its practical implications in engineering design. Experiments have been conducted in a recirculating free surface water channel, with a working section of dimensions 1 × 1.1 × 2.5 m. A cylinder model made of a spring and a plastic cover was used for the experiments. It was placed horizontally and fully submerged in the water channel's free stream, hanging from two submersible load cells arranged to measure the total drag force on the cylinder. The model had several white points painted on its surface, so its VIV motion was obtained by imaging it with two cameras synchronised with a strobe light. Image processing allowed to obtain the displacements along the length of the cylinder with sub-pixel accuracy. Digital Particle Image Velocimetry (DPIV) was also used to quantify the wake downstream the cylinder. A full set of experiments was made for reference purposes with a plain cylinder without suppressors, and for the same conditions, several passive suppression devices such as elastic splitter plates of different sizes and shapes, were installed on the cylinder. Passive VIV suppression with drag reduction was achieved with some of the configurations tested. Funding provided by the Spanish Ministry of Science through grant DPI2012-37904 is acknowledged.

  20. Dynamic characteristics of an inclined flexible cylinder undergoing vortex-induced vibrations

    Science.gov (United States)

    Han, Qinghua; Ma, Yexuan; Xu, Wanhai; Lu, Yan; Cheng, Ankang

    2017-04-01

    A series of experimental tests were conducted on vortex-induced vibrations (VIV) of a flexible inclined cylinder with a yaw angle equals 45° for investigating the response characteristics in a towing tank. The flexible cylinder model was 5.6 m in length and 16 mm in diameter with an aspect ratio of 350 and a mass ratio of 1.9. The Reynolds numbers ranged from about 800 to 16,000.The strain responses were measured directly in both cross-flow (CF) and in-line (IL) directions and corresponding displacements were obtained using a modal approach. The dynamic response characteristics of the inclined flexible cylinder excited by vortex shedding was examined from the aspect of strain response, displacement amplitudes, dominant modes, response frequencies and drag force coefficients. The experimental results indicated that the CF response amplitude could be up to a value of 3.0D and the IL one more than 1.1D. The dominant modes were from 1 to 3 in CF direction and 1 to 5 in IL direction. And it was found that dominant frequencies increased linearly with the reduced velocity. The multi-modal response of the flexible inclined cylinder model excited by VIV was observed and analyzed. Moreover, the values of drag coefficients were in the range of 0.9-2.6.

  1. Predicting wind-induced vibrations of high-rise buildings using unsteady CFD and modal analysis

    KAUST Repository

    Zhang, Yue

    2015-01-01

    This paper investigates the wind-induced vibration of the CAARC standard tall building model, via unsteady Computational Fluid Dynamics (CFD) and a structural modal analysis. In this numerical procedure, the natural unsteady wind in the atmospheric boundary layer is modeled with an artificial inflow turbulence generation method. Then, the turbulent flow is simulated by the second mode of a Zonal Detached-Eddy Simulation, and a conservative quadrature-projection scheme is adopted to transfer unsteady loads from fluid to structural nodes. The aerodynamic damping that represents the fluid-structure interaction mechanism is determined by empirical functions extracted from wind tunnel experiments. Eventually, the flow solutions and the structural responses in terms of mean and root mean square quantities are compared with experimental measurements, over a wide range of reduced velocities. The significance of turbulent inflow conditions and aeroelastic effects is highlighted. The current methodology provides predictions of good accuracy and can be considered as a preliminary design tool to evaluate the unsteady wind effects on tall buildings.

  2. Signal analysis of acoustic and flow-induced vibrations of BWR main steam line

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, G., E-mail: gepe@xanum.uam.mx [División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, México, D.F. 09340 (Mexico); Prieto-Guerrero, A. [División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, México, D.F. 09340 (Mexico); Núñez-Carrera, A. [Comisión Nacional de Seguridad Nuclear y Salvaguardias, Doctor Barragán 779, Col. Narvarte, México, D.F. 03020 (Mexico); Vázquez-Rodríguez, A. [División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, México, D.F. 09340 (Mexico); Centeno-Pérez, J. [Instituto Politécnico Nacional, Escuela Superior de Física y Matemáticas Unidad Profesional “Adolfo López Mateos”, Av. IPN, s/n, México, D.F. 07738 (Mexico); Espinosa-Martínez, E.-G. [Departamento de Sistemas Energéticos, Universidad Nacional Autónoma de México, México, D.F. 04510 (Mexico); and others

    2016-05-15

    Highlights: • Acoustic and flow-induced vibrations of BWR are analyzed. • BWR performance after extended power uprate is considered. • Effect of acoustic side branches (ASB) is analyzed. • The ASB represents a reduction in the acoustic loads to the steam dryer. • Methodology developed for simultaneous analyzing the signals in the MSL. - Abstract: The aim of this work is the signal analysis of acoustic waves due to phenomenon known as singing in Safety Relief Valves (SRV) of the main steam lines (MSL) in a typical BWR5. The acoustic resonance in SRV standpipes and fluctuating pressure is propagated from SRV to the dryer through the MSL. The signals are analyzed with a novel method based on the Multivariate Empirical Mode Decomposition (M-EMD). The M-EMD algorithm has the potential to find common oscillatory modes (IMF) within multivariate data. Based on this fact, we implement the M-EMD technique to find the oscillatory mode in BWR considering the measurements obtained collected by the strain gauges located around the MSL. These IMF, analyzed simultaneously in time, allow obtaining an estimation of the effects of the multiple-SRV in the MSL. Two scenarios are analyzed: the first is the signal obtained before the installation of the acoustic dampers (ASB), and the second, the signal obtained after installation. The results show the effectiveness of the ASB to damp the strong resonances when the steam flow increases, which represents an important reduction in the acoustic loads to the steam dryer.

  3. Effects Of Whole Body Vibration On Vertical Jump Performance Following Exercise Induced Muscle Damage

    Directory of Open Access Journals (Sweden)

    Nicole C. Dabbs

    2014-01-01

    Full Text Available Enhancing vertical jump performance is critical for many sports. Following high intensity training, individuals often experience exercise induced muscle damage (EIMD. Many recovery modalities have been tested with conflicting results. The purpose of this investigation was to determine the effect of whole-body vibration (WBV on vertical jump performance following EIMD. 27 females volunteered for 7 sessions and were randomly assigned to a treatment or control group and administered each testing day. Vertical jump performance was assessed via vertical jump height (VJH, peak power output (PPO, rate of force development (RFD, relative ground reaction force (GRFz, and peak activation ratio of the vastus medialis (VM via electromyography (EMG before and after 3 days of EIMD via split squats. Two testing sets were collected each day, consisting of pre measures followed by WBV or control, and then post second measures. A 2x8 (group x time mixed factor analysis of variance (ANOVA was conducted for each variable. No significant interactions or group differences were found in any variable. Significant main effects for time were found in any variable, indicating performance declined following muscle damage. These results indicate that WBV does not aid in muscle recovery or vertical jump performance following EIMD.

  4. Vortex-Induced Vibrations of a Square Cylinder with Damped Free-End Conditions

    Directory of Open Access Journals (Sweden)

    S. Manzoor

    2013-01-01

    Full Text Available The authors report the results of vortex-induced vibrations of a square cylinder in a wind tunnel. This constitutes a high mass ratio environment. The square cylinder is mounted in the wind tunnel in such a fashion that it only performs rigid body oscillations perpendicular to the flow direction with damped free-end conditions. This physical situation allows a direct evaluation for analytical models relying on simplified 2D assumptions. The results are also compared with two-dimensional fluid-structure (CFD-CSD numerical simulations. The comparison shows that despite having one-dimensional motion, the analytical model does not predict the VIV region with correctness. Results show that the numerical simulations and experimental results differ from the analytical model for the prediction of reduced velocity corresponding to peak amplitude. Also the analytical reduced velocity envelope is underpredicted compared to both numerical simulations and experimental data despite the structure being lightly damped. The findings are significant as the experimental results for freely oscillating high mass ratio body show differences from the low mass ratio especially in the transition between VIV and galloping regions. However the numerical simulations show comparatively close agreement.

  5. Assessment of the impact of VIV (Vortex Induced Vibrations) on closely spaced production jumpers

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Marcoux, Jean-Francois; Legras, Jean-Luc; Bastos, Renato; Rochereau, Max [Acergy, London (United Kingdom)

    2009-12-19

    Brazilian deep water projects require new concepts both for Early Production and Extended Tests Systems for which Floating Production units with smaller hulls are cost-efficient. Further more the Brazilian environment precludes spread mooring. This results in closely spaced riser configurations. Acergy has investigated the issue of interference between closely spaced risers for a few years in practice (bundle Riser Towers, SCR's), experimentally (with Scripps Institution of Oceanography), and with CFD (with Texas A and M University). The result has been in 2008 the inclusion of the Blevins model in commercially available software. Nevertheless the assessment of the impact of VIV of the upstream riser remained elusive. Measurements performed in 2007 confirmed that the wake behind a cylinder under VIV was expanded and the hydrodynamic forces on the downstream riser strongly affected when the upstream cylinder was undergoing Vortex Induced Vibrations (VIV). Measurements conducted in 2008 up to a Reynolds number of 140 000 appear to validate an engineering approach of the impact of VIV that can be readily included in commercially available software for design engineering purpose. The paper describes the experimental measurements, the proposed wake model, comparison of the measurements and model. Application to the design of deep water riser and jumper systems is also included. (author)

  6. Harvesting microalgal biomass using a magnetically induced membrane vibration (MMV) system: filtration performance and energy consumption.

    Science.gov (United States)

    Bilad, M R; Discart, V; Vandamme, D; Foubert, I; Muylaert, K; Vankelecom, Ivo F J

    2013-06-01

    This study was performed to investigate the effectiveness of submerged microfiltration to harvest both a marine diatom Phaeodactylum tricornutum and a Chlorella vulgaris in a recently developed magnetically induced membrane vibrating (MMV) system. We assess the filtration performance by conducting the improved flux step method (IFM), fed-batch concentration filtrations and membrane fouling autopsy using two lab-made membranes with different porosity. The full-scale energy consumption was also estimated. Overall results suggest that the MMV offers a good fouling control and the process was proven to be economically attractive. By combining the membrane filtration (15× concentration) with centrifugation to reach a final concentration of 25% w/v, the energy consumption to harvest P. tricornutum and C. vulgaris was, respectively, as low as 0.84 and 0.77kWh/m(3), corresponding to 1.46 and 1.39 kWh/kg of the harvested biomass. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Stress-Induced Neurodegeneration: Mechanisms and Interventions

    National Research Council Canada - National Science Library

    Meyerhoff, James

    2000-01-01

    ...) memory function has been localized to the hippocampus. Humans exposed to extreme stress for sustained periods have suffered deterioration of memory and inability to concentrate, as well as CNS atrophy...

  8. Anharmonicity of lattice vibrations induced by charged nickel additions in A sup 2 B sup 6 semiconductors

    CERN Document Server

    Sokolov, V I; Shirokov, E A; Kislov, A N

    2002-01-01

    Paper presents the results of investigations into lattice vibrations induced by nickel impurities charged negatively as to the lattice in ZnSe:Ni, ZnO:Ni, ZnS:Ni, CdS:Ni semiconductors. To investigate into vibrations one applies a sensitive technique of field exciton-oscillation spectroscopy. One observes experimentally oscillating reiterations of the impurity exciton head line including the intensive peaks of combined repetitions up to the 8-th order. The experimental results are discussed on the basis of the model estimations of oscillations of a lattice with a charged impurity centre, as well as, on the ground of calculations for oscillations of monoatomic chain with high anharmonicity. Charged impurity centres are shown to induce new oscillations of lattice - impurity anharmonic modes

  9. Composite Struts Would Damp Vibrations

    Science.gov (United States)

    Dolgin, Benjamin P.

    1991-01-01

    New design of composite-material (fiber/matrix laminate) struts increases damping of longitudinal vibrations without decreasing longitudinal stiffness or increasing weight significantly. Plies with opposing chevron patterns of fibers convert longitudinal vibrational stresses into shear stresses in intermediate viscoelastic layer, which dissipate vibrational energy. Composite strut stronger than aluminum strut of same weight and stiffness.

  10. Coupling effects of nonlocal and modified couple stress theories incorporating surface energy on analytical transverse vibration of a weakened nanobeam

    Science.gov (United States)

    Sourki, R.; Hosseini, S. A.

    2017-04-01

    An analytical solution to the flexural vibration of a weakened nanobeam on the basis of the nonlocal modified couple stress theory including surface effects is under consideration. In this investigation nanobeams are studied within the framework of the Euler-Bernoulli beam theory. The nanobeam is weakened by a crack modeled as a rotational spring at the crack position. This assumption divides the beam into two sections, invoking additional conditions on the beam. The governing equations and boundary conditions for the beam are obtained by applying the Hamilton principle. The natural frequencies for the cracked nanobeam are determined to investigate the effects of crack severity, crack position, nonlocal parameter, material length scale parameter and surface effect parameters. It has been found that the mentioned parameters have considerable effects on stiffness and have a significant impact the dynamic behavior of the nanobeam.

  11. Analysis of nelfinavir-induced endoplasmic reticulum stress.

    Science.gov (United States)

    Brüning, Ansgar

    2011-01-01

    Nelfinavir (Viracept®) is an HIV protease inhibitor that has been shown to induce the endoplasmic reticulum (ER) stress reaction in human cancer cells. Although the presumed drug doses needed for an efficient ER stress reaction and ensuing apoptosis in cancer cells is somewhat higher than those prescribed for HIV-infected persons, nelfinavir represents one of the few clinically applicable ER stress-inducing agents, and is currently being tested in clinical studies on cancer patients. Therefore, this chapter describes how to obtain and use nelfinavir for in vitro and in vivo studies. In addition, methods are described that might facilitate the analysis and monitoring of the nelfinavir-induced ER stress response either in cancer cells in cell culture or in cancer tissue biopsies. These methods include various fluorescence-based ER staining techniques and the expression analysis of primary and secondary ER stress markers by immunoblotting and RT-PCR analysis. Among the several methods presented, the analysis of an unconventional XBP1 splicing, caused by the ER stress sensor IRE1, is shown to present the most sensitive and most specific marker for nelfinavir-induced ER stress. Primers and PCR conditions suitable for XBP1 PCR and splicing analysis are presented. Such a PCR-based XBP1 splicing analysis might not only be suitable to monitor nelfinavir-induced ER stress, but could also be applied in drug screening programs to test for other ER stress-inducing agents with similar activities or synergistic activities with nelfinavir. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Dependence of the frequency spectrum of small amplitude vibrations superimposed on finite deformations of a nonlinear, cylindrical elastic body on residual stress

    KAUST Repository

    Gorb, Yuliya

    2010-11-01

    We model and analyze the response of nonlinear, residually stressed elastic bodies subjected to small amplitude vibrations superimposed upon large deformations. The problem derives from modeling the use of intravascular ultrasound (IVUS) imaging to interrogate atherosclerotic plaques in vivo in large arteries. The goal of this investigation is twofold: (i) introduce a modeling framework for residual stress that unlike traditional Fung type classical opening angle models may be used for a diseased artery, and (ii) investigate the sensitivity of the spectra of small amplitude high frequency time harmonic vibrations superimposed on a large deformation to the details of the residual stress stored in arteries through a numerical simulation using physiologic parameter values under both low and high blood pressure loadings. The modeling framework also points the way towards an inverse problem using IVUS techniques to estimate residual stress in healthy and diseased arteries. © 2010 Elsevier Ltd. All rights reserved.

  13. Analysis of the Suppression Device as Vortex Induced Vibration (VIV Reducer on Free Span using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Dwi Priyanta

    2016-12-01

    Full Text Available Subsea pipeline is a transportation infrastructure of oil and gas as an alternative for ship tanker. The uneven topography surface of the sea floor resulting the pipe undergoes free span. The free span is a condition endured by the pipe where the pipe position has  distance or gap with the seabed supported by two pivot. The free span is at risk of experiencing a vibration caused by the presence of dynamic load that is current and the wave. The vibration that occurs is the impact of the presence of the phenomenon of Vortex Induced Vibration (VIV. The Phenomenon Of VIV occur on a cylindrical component caused by ocean currents, causing the occurrence of vibration by the movement of fluid on the pipe so that it raises the vortex at the rear of the direction of oncoming flow. One way to dampen or reduce the impact of VIV is by adding suppresion device. VIV suppression device is a tool that is installed on the pipeline on offshore piping installationcthat serves to dampen or reduce the impact of VIV. One of the simulations used to know the characteristics of a fluid is to use (CFD Computational Fluid Dynamic. With the addition of suppression device can add the rest of the operating time on a free span of affected VIV, on the condition of free span critical exposed VIV (Vortex Induced Vibration value has a life time on plain pipe 44.21 years, on pipe with 53.09 years and Fairing on the pipe with the Helical strike 52.95 year.

  14. Simple evaluations of fluid-induced vibrations for steam generator tube arrays in advanced marine reactors (MRX, DRX)

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kazuo [Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan); Ishida, Toshihisa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-06-01

    Advanced Marine Reactor (MRX) and Deep Sea Research Reactor (DRX) are the integral-type PWR, and the steam generators are installed in the reactor vessels. Steam generators are of the once-through, helical-coil tube types. Heat transfer tubes surround inner shroud in annular space of the reactor vessel. Flow-induced vibrations are calculated by simple methods, and the arrangement of tube support structures are evaluated. (author)

  15. Wind-induced cable vibrations and countermeasures of cables of PC cable-stayed bridge. PC syachokyo keburu no kaze ni yoru shindo to sono taisaku

    Energy Technology Data Exchange (ETDEWEB)

    Yoneda, M. (Kawada Industries Inc., Tokyo (Japan))

    1994-05-01

    In recent years, long span of cable-stayed bridges is remarkable. The wind-induced cable vibration called as line vibration and wake galloping was given as an important problem not only in the steel cable-stayed bridges but also in the PC cable-stayed bridges. The technical engineers in design of the cable-stayed bridges have many times to confront the problems on the vibration control of cables, it is considered that sufficient understand of the wind-induced vibration and countermeasures for cables of the PC cable-stayed bridges is necessary. Many reports on the countermeasure examples and trend of vibration control centred on cables of the cable-stayed bridges have been published. In this paper, the wind-induced vibration of cables in the cable-stayed bridges was reviewed, the examples of countermeasures of vibration control on cables in the PC cable-stayed bridges was mainly introduced. The remaining tasks and future prospects on vibration control of the PC cable-stayed bridges were described. 14 refs., 13 figs., 4 tabs.

  16. Interaction dynamics of gap flow with vortex-induced vibration in side-by-side cylinder arrangement

    Science.gov (United States)

    Liu, Bin; Jaiman, Rajeev K.

    2016-12-01

    A numerical investigation of the vortex-induced vibration (VIV) in a side-by-side circular cylinder arrangement has been performed in a two-dimensional laminar flow environment. One of the cylinders is elastically mounted and only vibrates in the transverse direction, while its counterpart remains stationary in a uniform flow stream. When the gap ratio is sufficiently small, the flip-flopping phenomenon of the gap flow can be an additional time-dependent interference to the flow field. This phenomenon was reported in the experimental work of Bearman and Wadcock ["The interaction between a pair of circular cylinders normal to a stream," J. Fluid Mech. 61(3), 499-511 (1973)] in a side-by-side circular cylinder arrangement, in which the gap flow deflects toward one of the cylinders and switched its sides intermittently. Albeit one of the two cylinders is free to vibrate, the flip-flop of a gap flow during VIV dynamics can still be observed outside the lock-in region. The exact moments of the flip-flop phenomenon due to spontaneous symmetry breaking are observed in this numerical study. The significant characteristic vortex modes in the near-wake region are extracted via dynamic modal analysis and the interference between the gap flow and VIV is found to be mutual. In a vibrating side-by-side arrangement, the lock-in region with respect to reduced velocity becomes narrower due to the interference from its stationary counterpart. The frequency lock-in occurs and ends earlier than that of an isolated vibrating circular cylinder subjected to an identical flow environment. Similar to a tandem cylinder arrangement, in the post-lock-in region, the maximum vibration amplitudes are escalated compared with those of an isolated circular cylinder configuration. On the other hand, subjected to the influence from VIV, the biased gap flow deflects toward the vibrating cylinder quasi-stably during the frequency lock-in process. This behavior is different from the reported bi

  17. Embedding human annoyance rate models in wireless smart sensors for assessing the influence of subway train-induced ambient vibration

    Science.gov (United States)

    Sun, Ke; Zhang, Wei; Ding, Huaping; Kim, Robin E.; Spencer, Billie F., Jr.

    2016-10-01

    The operation of subway trains induces ambient vibrations, which may cause annoyance and other adverse effects on humans, eventually leading to physical, physiological, and psychological problems. In this paper, the human annoyance rate (HAR) models, used to assess the human comfort under the subway train-induced ambient vibrations, were deduced and the calibration curves for 5 typical use circumstances were addressed. An autonomous measurement system, based on the Imote2, wireless smart sensor (WSS) platform, plus the SHM-H, high-sensitivity accelerometer board, was developed for the HAR assessment. The calibration curves were digitized and embedded in the computational core of the WSS unit. Experimental validation was conducted, using the developed system on a large underground reinforced concrete frame structure adjoining the subway station. The ambient acceleration of both basement floors was measured; the embedded computation was implemented and the HAR assessment results were wirelessly transmitted to the central server, all by the WSS unit. The HAR distributions of the testing areas were identified, and the extent to which both basements will be influenced by the close-up subway-train’s operation, in term of the 5 typical use circumstances, were quantitatively assessed. The potential of the WSS-based autonomous system for the fast environment impact assessment of the subway train-induced ambient vibration was well demonstrated.

  18. Mercury chloride-induced oxidative stress in human erythrocytes ...

    African Journals Online (AJOL)

    ONOS

    2010-01-25

    Jan 25, 2010 ... Key words: Mercury chloride, vitamins C and E, oxidative stress, erythrocytes, in vitro. ... of free radicals induced by oxidative damage to lipids and lipoproteins in various cellular ... metals toxicity in different experimental systems ..... vitamins C, E and beta carotene aganist gamma-ray-induced DNA damage ...

  19. Effect of stress-induced grain growth during room temperature ...

    Indian Academy of Sciences (India)

    -induced grain ... The TEM observations reveal that stress-induced grain growth during tensile deformation is significantly suppressed for the nc Ni–Co alloys rich in Co in sharp contrast to those poor in Co. We believe that sufficient solutes ...

  20. Environmental stress induces trinucleotide repeat mutagenesis in human cells

    Science.gov (United States)

    Chatterjee, Nimrat; Lin, Yunfu; Santillan, Beatriz A.; Yotnda, Patricia; Wilson, John H.

    2015-01-01

    The dynamic mutability of microsatellite repeats is implicated in the modification of gene function and disease phenotype. Studies of the enhanced instability of long trinucleotide repeats (TNRs)—the cause of multiple human diseases—have revealed a remarkable complexity of mutagenic mechanisms. Here, we show that cold, heat, hypoxic, and oxidative stresses induce mutagenesis of a long CAG repeat tract in human cells. We show that stress-response factors mediate the stress-induced mutagenesis (SIM) of CAG repeats. We show further that SIM of CAG repeats does not involve mismatch repair, nucleotide excision repair, or transcription, processes that are known to promote TNR mutagenesis in other pathways of instability. Instead, we find that these stresses stimulate DNA rereplication, increasing the proportion of cells with >4 C-value (C) DNA content. Knockdown of the replication origin-licensing factor CDT1 eliminates both stress-induced rereplication and CAG repeat mutagenesis. In addition, direct induction of rereplication in the absence of stress also increases the proportion of cells with >4C DNA content and promotes repeat mutagenesis. Thus, environmental stress triggers a unique pathway for TNR mutagenesis that likely is mediated by DNA rereplication. This pathway may impact normal cells as they encounter stresses in their environment or during development or abnormal cells as they evolve metastatic potential. PMID:25775519

  1. Low frequency vibrations induce malformations in two aquatic species in a frequency-, waveform-, and direction-specific manner.

    Directory of Open Access Journals (Sweden)

    Laura N Vandenberg

    Full Text Available Environmental toxicants such as industrial wastes, air particulates from machinery and transportation vehicles, and pesticide run-offs, as well as many chemicals, have been widely studied for their effects on human and wildlife populations. Yet other potentially harmful environmental pollutants such as electromagnetic pulses, noise and vibrations have remained incompletely understood. Because developing embryos undergo complex morphological changes that can be affected detrimentally by alterations in physical forces, they may be particularly susceptible to exposure to these types of pollutants. We investigated the effects of low frequency vibrations on early embryonic development of two aquatic species, Xenopus laevis (frogs and Danio rerio (zebrafish, specifically focusing on the effects of varying frequencies, waveforms, and applied direction. We observed treatment-specific effects on the incidence of neural tube defects, left-right patterning defects and abnormal tail morphogenesis in Xenopus tadpoles. Additionally, we found that low frequency vibrations altered left-right patterning and tail morphogenesis, but did not induce neural tube defects, in zebrafish. The results of this study support the conclusion that low frequency vibrations are toxic to aquatic vertebrates, with detrimental effects observed in two important model species with very different embryonic architectures.

  2. A Numerical Study of the Screening Effectiveness of Open Trenches for High-Speed Train-Induced Vibration

    Directory of Open Access Journals (Sweden)

    Chih-hung Chiang

    2014-01-01

    Full Text Available This study used the 2D boundary element method in time domain to examine the screening effectiveness of open trenches on reducing vibration generated by a high-speed train. The parameters included configurations of the trench, train speed, the distance between the source and the trench, and the Poisson’s ratio of the soil. A reducing displacement level (in dB scale was defined and used to evaluate the screening effectiveness of a wave barrier. The maximal reducing displacement level reached 25 dB when an open trench was used as a wave barrier. The depth of an open trench is a main influential parameter of screening effectiveness. The cutoff frequency of the displacement spectrum increases with decreasing trench depth. The maximal screening effectiveness occurs when the depth is 0.3-0.4 Rayleigh wavelength. Using an open trench as a wave barrier can reduce 10–25 dB of vibration amplitude at frequencies between 30 and 70 Hz. A considerable increase in screening effectiveness of the open trench was observed from 30 to 70 Hz, which matches the main frequencies of vibration induced by Taiwan High Speed Rail. The influence of trench width on screening effectiveness is nonsignificant except for frequencies from 30 to 40 Hz. Poisson’s ratio has various effects on the reduction of vibration at frequencies higher than 30 Hz.

  3. Relationship between sound radiation from sound-induced and force-excited vibration: Analysis using an infinite elastic plate model.

    Science.gov (United States)

    Yairi, Motoki; Sakagami, Kimihiro; Nishibara, Kosuke; Okuzono, Takeshi

    2016-07-01

    Although sound radiation from sound-induced vibration and from force-excited vibration of solid structures are similar phenomena in terms of radiating from vibrating structures, the general relationship between them has not been explicitly studied to date. In particular, airborne sound transmission through walls and sound radiation from structurally vibrating surfaces in buildings are treated as different issues in architectural acoustics. In this paper, a fundamental relationship is elucidated through the use of a simple model. The transmission coefficient for random-incidence sound and the radiated sound power under point force excitation of an infinite elastic plate are both analyzed. Exact and approximate solutions are derived for the two problems, and the relationship between them is theoretically discussed. A conversion function that relates the transmission coefficient and radiated sound power is obtained in a simple closed form through the approximate solutions. The exact solutions are also related by the same conversion function. It is composed of the specific impedance and the wavenumber, and is independent of any elastic plate parameters. The sound radiation due to random-incidence sound and point force excitation are similar phenomena, and the only difference is the gradient of those characteristics with respect to the frequency.

  4. Serotonergic involvement in stress-induced vasopressin and oxytocin secretion

    DEFF Research Database (Denmark)

    Jørgensen, Henrik; Knigge, Ulrich; Kjaer, Andreas

    2002-01-01

    OBJECTIVE: To investigate the involvement of serotonin (5-hydroxytryptamine - 5-HT) receptors in mediation of stress-induced arginine vasopressin (AVP) and oxytocin (OT) secretion in male rats. DESIGN: Experiments on laboratory rats with control groups. METHODS: Different stress paradigms were...... applied after pretreatment with intracerebroventricular infusion of saline or different 5-HT antagonists. RESULTS: Restraint stress (5 min), hypotensive hemorrhage or dehydration for 24 h increased AVP secretion fivefold and OT secretion threefold. Swim stress for 3 min had no effect on AVP secretion...

  5. Vibration-Induced Motor Responses of Infants With and Without Myelomeningocele

    Science.gov (United States)

    Teulier, Caroline; Smith, Beth A.; Kim, Byungji; Beutler, Benjamin D.; Martin, Bernard J.; Ulrich, Beverly D.

    2012-01-01

    Background The severity of myelomeningocele (MMC) stems both from a loss of neurons due to neural tube defect and a loss of function in viable neurons due to reduced movement experience during the first year after birth. In young infants with MMC, the challenge is to reinforce excitability and voluntary control of all available neurons. Muscle vibration paired with voluntary movement may increase motoneuron excitability and contribute to improvements in neural organization, responsiveness, and control. Objectives This study examined whether infants with or without MMC respond to vibration by altering their step or stance behavior when supported upright on a treadmill. Design This was a cross-sectional study. Methods Twenty-four 2- to 10-month-old infants, 12 with typical development (TD) and 12 with MMC (lumbar and sacral lesions), were tested. Infants were supported upright with their feet in contact with a stationary or moving treadmill during 30-second trials. Rhythmic alternating vibrations were applied to the right and left rectus femoris muscles, the lateral gastrocnemius muscle, or the sole of the foot. Two cameras and behavior coding were used to determine step count, step type, and motor response to vibration onset. Results Step count decreased and swing duration increased in infants with TD during vibration of the sole of the foot on a moving treadmill (FT-M trials). Across all groups the percentage of single steps increased during vibration of the lateral gastrocnemius muscle on a moving treadmill. Infants with MMC and younger infants with TD responded to onset of vibration with leg straightening during rectus femoris muscle stimulation and by stepping during FT-M trials more often than older infants with TD. Conclusions Vibration seems a viable option for increasing motor responsiveness in infants with MMC. Follow-up studies are needed to identify optimal methods of administering vibration to maximize step and stance behavior in infants. PMID:22228610

  6. A new paradigm to induce mental stress: The Sing-a-Song Stress Test (SSST

    Directory of Open Access Journals (Sweden)

    Anne-Marie eBrouwer

    2014-07-01

    Full Text Available We here introduce a new experimental paradigm to induce mental stress in a quick and easy way while adhering to ethical standards and controlling for potential confounds resulting from sensory input and body movements. In our Sing-a-Song Stress Test, participants are presented with neutral messages on a screen, interleaved with 1-minute time intervals. The final message is that the participant should sing a song aloud after the interval has elapsed. Participants sit still during the whole procedure. We found that heart rate and skin conductance during the 1-minute intervals following the sing-a-song stress message are substantially higher than during intervals following neutral messages. The order of magnitude of the rise is comparable to that achieved by the Trier Social Stress Test. Skin conductance increase correlates positively with experienced stress level as reported by participants. We also simulated stress detection in real time. When using both skin conductance and heart rate, stress is detected for 18 out of 20 participants, approximately 10s after onset of the sing-a-song message. In conclusion, the Sing-a-Song Stress Test provides a quick, easy, controlled and potent way to induce mental stress and could be helpful in studies ranging from examining physiological effects of mental stress to evaluating interventions to reduce stress.

  7. Stress Leukogram Induced by Acute and Chronic Stress in Zebrafish (Danio rerio).

    Science.gov (United States)

    Grzelak, Agata K; Davis, Daniel J; Caraker, Susan M; Crim, Marcus J; Spitsbergen, Jan M; Wiedmeyer, Charles E

    2017-06-01

    The use of zebrafish (Danio rerio) as an animal model for experimental studies of stress has increased rapidly over the years. Although many physiologic and behavioral characteristics associated with stress have been defined in zebrafish, the effects of stress on hematologic parameters have not been described. The purpose of our study was to induce a rise in endogenous cortisol through various acute and chronic stressors and compare the effects of these stressors on peripheral WBC populations. Acutely stressed fish underwent dorsal or full-body exposure to air for 3 min, repeated every 30 min over the course of 90 min. Chronically stressed fish underwent exposure to stressors twice daily over a period of 5 d. After the last stressful event, fish were euthanized, and whole blood and plasma were obtained. A drop of whole blood was used to create a blood smear, which was subsequently stained with a modified Wright-Giemsa stain and a 50-WBC differential count determined. Plasma cortisol levels were determined by using a commercially available ELISA. Endogenous cortisol concentrations were significantly higher in both stressed groups as compared with control fish. Acutely stressed fish demonstrated significant lymphopenia, monocytosis, and neutrophilia, compared with unstressed, control fish. Chronic stress induced lymphopenia and monocytosis but no significant changes in relative neutrophil populations in zebrafish. The changes in both stressed groups most likely are due to increases in endogenous cortisol concentrations and represent the first description of a stress leukogram in zebrafish.

  8. Stress proteins are induced by space environment

    Science.gov (United States)

    Takahashi, Akihisa; Ohnishi, Takeo

    The space environment contains two major biologically significant influences such as space radiations and microgravity. Almost all organisms possess essential recognition and response systems for environmental changes. The famous one of cellular stress responses is the gene induction of heat shock protein (HSP). HSP expression is increased under elevated temperatures, and also increased by other sources of cellular stress, including ionizing radiation, oxidative injury, osmotic stress and the unfolded protein response. HSPs assist in the folding and maintenance of newly translated proteins, the refolding of denatured proteins and the further unfolding of misfolded or destabilized proteins to protect the cell from crisis. Based on our space experiment, we report the results and discussion from the viewpoint of HSP expression after exposure to space environment.

  9. Stress-Induced Chronic Visceral Pain of Gastrointestinal Origin

    Directory of Open Access Journals (Sweden)

    Beverley Greenwood-Van Meerveld

    2017-11-01

    Full Text Available Visceral pain is generally poorly localized and characterized by hypersensitivity to a stimulus such as organ distension. In concert with chronic visceral pain, there is a high comorbidity with stress-related psychiatric disorders including anxiety and depression. The mechanisms linking visceral pain with these overlapping comorbidities remain to be elucidated. Evidence suggests that long term stress facilitates pain perception and sensitizes pain pathways, leading to a feed-forward cycle promoting chronic visceral pain disorders such as irritable bowel syndrome (IBS. Early life stress (ELS is a risk-factor for the development of IBS, however the mechanisms responsible for the persistent effects of ELS on visceral perception in adulthood remain incompletely understood. In rodent models, stress in adult animals induced by restraint and water avoidance has been employed to investigate the mechanisms of stress-induce pain. ELS models such as maternal separation, limited nesting, or odor-shock conditioning, which attempt to model early childhood experiences such as neglect, poverty, or an abusive caregiver, can produce chronic, sexually dimorphic increases in visceral sensitivity in adulthood. Chronic visceral pain is a classic example of gene × environment interaction which results from maladaptive changes in neuronal circuitry leading to neuroplasticity and aberrant neuronal activity-induced signaling. One potential mechanism underlying the persistent effects of stress on visceral sensitivity could be epigenetic modulation of gene expression. While there are relatively few studies examining epigenetically mediated mechanisms involved in visceral nociception, stress-induced visceral pain has been linked to alterations in DNA methylation and histone acetylation patterns within the brain, leading to increased expression of pro-nociceptive neurotransmitters. This review will discuss the potential neuronal pathways and mechanisms responsible for

  10. Stress-Induced Chronic Visceral Pain of Gastrointestinal Origin

    Science.gov (United States)

    Greenwood-Van Meerveld, Beverley; Johnson, Anthony C.

    2017-01-01

    Visceral pain is generally poorly localized and characterized by hypersensitivity to a stimulus such as organ distension. In concert with chronic visceral pain, there is a high comorbidity with stress-related psychiatric disorders including anxiety and depression. The mechanisms linking visceral pain with these overlapping comorbidities remain to be elucidated. Evidence suggests that long term stress facilitates pain perception and sensitizes pain pathways, leading to a feed-forward cycle promoting chronic visceral pain disorders such as irritable bowel syndrome (IBS). Early life stress (ELS) is a risk-factor for the development of IBS, however the mechanisms responsible for the persistent effects of ELS on visceral perception in adulthood remain incompletely understood. In rodent models, stress in adult animals induced by restraint and water avoidance has been employed to investigate the mechanisms of stress-induce pain. ELS models such as maternal separation, limited nesting, or odor-shock conditioning, which attempt to model early childhood experiences such as neglect, poverty, or an abusive caregiver, can produce chronic, sexually dimorphic increases in visceral sensitivity in adulthood. Chronic visceral pain is a classic example of gene × environment interaction which results from maladaptive changes in neuronal circuitry leading to neuroplasticity and aberrant neuronal activity-induced signaling. One potential mechanism underlying the persistent effects of stress on visceral sensitivity could be epigenetic modulation of gene expression. While there are relatively few studies examining epigenetically mediated mechanisms involved in visceral nociception, stress-induced visceral pain has been linked to alterations in DNA methylation and histone acetylation patterns within the brain, leading to increased expression of pro-nociceptive neurotransmitters. This review will discuss the potential neuronal pathways and mechanisms responsible for stress-induced

  11. Overlay degradation induced by film stress

    Science.gov (United States)

    Huang, Chi-hao; Liu, Yu-Lin; Luo, Shing-Ann; Yang, Mars; Yang, Elvis; Hung, Yung-Tai; Luoh, Tuung; Yang, T. H.; Chen, K. C.

    2017-03-01

    The semiconductor industry has continually sought the approaches to produce memory devices with increased memory cells per memory die. One way to meet the increasing storage capacity demand and reduce bit cost of NAND flash memories is 3D stacked flash cell array. In constructing 3D NAND flash memories, increasing the number of stacked layers to build more memory cell number per unit area necessitates many high-aspect-ratio etching processes accordingly the incorporation of thick and unique etching hard-mask scheme has been indispensable. However, the ever increasingly thick requirement on etching hard-mask has made the hard-mask film stress control extremely important for maintaining good process qualities. The residual film stress alters the wafer shape consequently several process impacts have been readily observed across wafer, such as wafer chucking error on scanner, film peeling, materials coating and baking defects, critical dimension (CD) non-uniformity and overlay degradation. This work investigates the overlay and residual order performance indicator (ROPI) degradation coupling with increasingly thick advanced patterning film (APF) etching hard-mask. Various APF films deposited by plasma enhanced chemical vapor deposition (PECVD) method under different deposition temperatures, chemicals combinations, radio frequency powers and chamber pressures were carried out. And -342MPa to +80MPa film stress with different film thicknesses were generated for the overlay performance study. The results revealed the overlay degradation doesn't directly correlate with convex or concave wafer shapes but the magnitude of residual APF film stress, while increasing the APF thickness will worsen the overlay performance and ROPI strongly. High-stress APF film was also observed to enhance the scanner chucking difference and lead to more serious wafer to wafer overlay variation. To reduce the overlay degradation from ever increasingly thick APF etching hard-mask, optimizing the

  12. Residual Stress Induced by Nitriding and Nitrocarburizing

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2005-01-01

    The present chapter is devoted to the various mechanisms involved in the buildup and relief of residual stress in nitrided and nitrocarburized cases. The work presented is an overview of model studies on iron and iron-based alloys. Subdivision is made between the compound (or white) layer, develo......, developing at the surfce and consisting of iron-based (carbo)nitrides, and the diffusion zone underneath, consisting of iron and alloying element nitrides dispersed in af ferritic matrix. Microstructural features are related directly to the origins of stress buildup and stres relief....

  13. Pre-cold stress increases acid stress resistance and induces amino ...

    African Journals Online (AJOL)

    Pre-cold stress increases acid stress resistance and induces amino acid homeostasis in Lactococcus lactis. NZ9000. Taher Khakpour Moghaddam1,2, Juan Zhang1,2, Guocheng Du1,2*. 1Key Laboratory of Industrial Biotechnology, Ministry of Education, 2School of Biotechnology, Jiangnan University, Wuxi,. Jiangsu ...

  14. A new paradigm to induce mental stress : the Sing-a-Song Stress Test(SSST)

    NARCIS (Netherlands)

    Brouwer, A.M.; Hogervorst, M.A.

    2014-01-01

    We here introduce a new experimental paradigm to induce mental stress in a quick and easy way while adhering to ethical standards and controlling for potential confounds resulting from sensory input and body movements. In our Sing-a-Song Stress Test, participants are presented with neutral messages

  15. Thiamine deficiency induces endoplasmic reticulum stress and oxidative stress in human neurons derived from induced pluripotent stem cells.

    Science.gov (United States)

    Wang, Xin; Xu, Mei; Frank, Jacqueline A; Ke, Zun-Ji; Luo, Jia

    2017-04-01

    Thiamine (vitamin B1) deficiency (TD) plays a major role in the etiology of Wernicke's encephalopathy (WE) which is a severe neurological disorder. TD induces selective neuronal cell death, neuroinflammation, endoplasmic reticulum (ER) stress and oxidative stress in the brain which are commonly observed in many aging-related neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and progressive supranuclear palsy (PSP). However, the underlying cellular and molecular mechanisms remain unclear. The progress in this line of research is hindered due to the lack of appropriate in vitro models. The neurons derived for the human induced pluripotent stem cells (hiPSCs) provide a relevant and powerful tool for the research in pharmaceutical and environmental neurotoxicity. In this study, we for the first time used human induced pluripotent stem cells (hiPSCs)-derived neurons (iCell neurons) to investigate the mechanisms of TD-induced neurodegeneration. We showed that TD caused a concentration- and duration-dependent death of iCell neurons. TD induced ER stress which was evident by the increase in ER stress markers, such as GRP78, XBP-1, CHOP, ATF-6, phosphorylated eIF2α, and cleaved caspase-12. TD also triggered oxidative stress which was shown by the increase in the expression 2,4-dinitrophenyl (DNP) and 4-hydroxynonenal (HNE). ER stress inhibitors (STF-083010 and salubrinal) and antioxidant N-acetyl cysteine (NAC) were effective in alleviating TD-induced death of iCell neurons, supporting the involvement of ER stress and oxidative stress. It establishes that the iCell neurons are a novel tool to investigate cellular and molecular mechanisms for TD-induced neurodegeneration. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Exposure to mobile phone electromagnetic field radiation, ringtone and vibration affects anxiety-like behaviour and oxidative stress biomarkers in albino wistar rats.

    Science.gov (United States)

    Shehu, Abubakar; Mohammed, Aliyu; Magaji, Rabiu Abdussalam; Muhammad, Mustapha Shehu

    2016-04-01

    Research on the effects of Mobile phone radio frequency emissions on biological systems has been focused on noise and vibrations as auditory stressors. This study investigated the potential effects of exposure to mobile phone electromagnetic field radiation, ringtone and vibration on anxiety-like behaviour and oxidative stress biomarkers in albino wistar rats. Twenty five male wistar rats were randomly divided into five groups of 5 animals each: group I: exposed to mobile phone in switched off mode (control), group II: exposed to mobile phone in silent mode, group III: exposed to mobile phone in vibration mode, group IV: exposed to mobile phone in ringtone mode, group V: exposed to mobile phone in vibration and ringtone mode. The animals in group II to V were exposed to 10 min call (30 missed calls for 20 s each) per day for 4 weeks. Neurobehavioural studies for assessing anxiety were carried out 24 h after the last exposure and the animals were sacrificed. Brain samples were collected for biochemical evaluation immediately. Results obtained showed a significant decrease (P electromagnetic radiation, vibration, ringtone or both produced a significant effect on anxiety-like behavior and oxidative stress in young wistar rats.

  17. Predicting Stress-induced Anisotropy around a Borehole

    Science.gov (United States)

    Fang, X.; Fehler, M.; Zhu, Z.; Toksoz, M. N.; Earth Resources Laboratory

    2010-12-01

    The knowledge of the in situ stress state around a borehole is of primary importance for investigating the stability of the borehole, when estimating the likely orientations of open fractures, and for designing hydraulic fracture operations. Two major steps may be used to estimate the in situ stress: first, we measure the near-wellbore anisotropy from acoustic logs, which can be done using a relatively well-developed technique; second, we use some inversion scheme to estimate the in situ stress state by assuming that all near-wellbore anisotropy is caused by the anisotropic near-wellbore stress field that has been altered by the presence of the borehole. In order to develop an accurate and efficient inversion scheme, the relation between the stress and formation anisotropy needs to be quantitatively determined. Because the stress field near the wellbore is strongly influenced by the presence of the borehole, in this paper, we propose an iterative numerical approach to estimate the stress-induced anisotropy around a borehole for any given stress state by applying Mavko’s model (1995) and a finite-element method. The accuracy of our approach is validated through laboratory measurements of the stress-strain relation of Berea sandstone under uniaxial loading. Our numerical studies show that this approach can be applied to calculate the formation anisotropy around a borehole for a wide stress range. This approach could potentially provide a good forward model for the in situ stress inversion.

  18. Oxidative stress and histopathological changes induced by ...

    African Journals Online (AJOL)

    Background: Methyl-thiophanate (MT), a fungicide largely used in agriculture throughout the world including Tunisia, protects many vegetables, fruits and field crops against a wide spectrum of fungal diseases. Oxidative stress has been proposed as a possible mechanism involved in MT toxicity on non-target organism.

  19. Pathophysiology of stress-induced visceral hypersensitivity

    NARCIS (Netherlands)

    Stanisor, O.I.

    2014-01-01

    Visceral hypersensitivity is observed in the majority of patients with IBS and considered a pathophysiological mechanism. The aim of the work described in this thesis was to obtain a better understanding of the stress-related pathophysiology of visceral hypersensitivity. Investigations were carried

  20. Desiccation stress induces developmental heterochrony in

    Indian Academy of Sciences (India)

    Stressful environments are known to perturb developmental patterns in insects. In the purview of desiccation as astressor, relatively little is known about the developmental consequences linked with desiccation tolerance. In thisstudy, we have particularly focused on the exploration of the temporal profile of postembryonic ...

  1. Vibration-Induced Nystagmus in Patients with Unilateral Peripheral Vestibular Disorders

    National Research Council Canada - National Science Library

    Xie, Sujiang; Guo, Jia; Wu, Ziming; Qiang, Dongchang; Huang, Jing; Zheng, Yingjuan; Yao, Qin; Chen, Shan; Tian, Dawei

    2013-01-01

    ...) and to calculate the sensitivity and the specificity of the vibration test. One hundred and twelve patients with unilateral peripheral vestibular disorders and thirty normal subjects were enrolled into this study...

  2. Tactile Perception of Roughness and Hardness to Discriminate Materials by Friction-Induced Vibration

    National Research Council Canada - National Science Library

    Shuyang Ding; Yunlu Pan; Mingsi Tong; Xuezeng Zhao

    2017-01-01

    ... skin. The tactile perception of surface roughness and material hardness can be estimated by skin vibrations generated during a fingertip stroking of a surface instead of being maintained in a static position...

  3. Effect of pile-driving induced vibrations on nearby structures and other assets.

    Science.gov (United States)

    2013-11-01

    The work described here represents an attempt to understand the mechanisms of energy : transfer from steel H-piles driven with diesel hammers to the surrounding soil and the energy : attenuation through the soil by measuring ground motion vibrations ...

  4. Stress-induced premature senescence or stress-induced senescence-like phenotype: one in vivo reality, two possible definitions?

    Science.gov (United States)

    Toussaint, Olivier; Dumont, Patrick; Remacle, José; Dierick, Jean-François; Pascal, Thierry; Frippiat, Christophe; Magalhaes, Joao Pedro; Zdanov, Stéphanie; Chainiaux, Florence

    2002-01-29

    No consensus exists so far on the definition of cellular senescence. The narrowest definition of senescence is irreversible growth arrest triggered by telomere shortening counting cell generations (definition 1). Other authors gave an enlarged functional definition encompassing any kind of irreversible arrest of proliferative cell types induced by damaging agents or cell cycle deregulations after overexpression of proto-oncogenes (definition 2). As stress increases, the proportion of cells in "stress-induced premature senescence-like phenotype" according to definition 1 or "stress-induced premature senescence," according to definition 2, should increase when a culture reaches growth arrest, and the proportion of cells that reached telomere-dependent replicative senescence due to the end-replication problem should decrease. Stress-induced premature senescence-like phenotype and telomere-dependent replicatively senescent cells share basic similarities such as irreversible growth arrest and resistance to apoptosis, which may appear through different pathways. Irreversible growth arrest after exposure to oxidative stress and generation of DNA damage could be as efficient in avoiding immortalisation as "telomere-dependent" replicative senescence. Probabilities are higher that the senescent cells (according to definition 2) appearing in vivo are in stress-induced premature senescence rather than in telomere-dependent replicative senescence. Examples are given suggesting these cells affect in vivo tissue (patho)physiology and aging.

  5. Disk/Shaft Vibration Induced by Bearing Clearance Effects: Analysis and Experiment

    Science.gov (United States)

    Flowers, George T.; Wu, Fangsheng

    1996-01-01

    This study presents an investigation of the dynamics of a rotor system with bearing clearance. Of particular interest is the influence of such effects on coupled disk/shaft vibration. Experimental results for a rotor system with a flexible disk are presented and compared to predictions from a simulation model. Some insights and conclusions are obtained with regard to the conditions under which such vibration may be significant.

  6. Modulating Oxidative Stress Relieves Stress-Induced Behavioral and Cognitive Impairments in Rats.

    Science.gov (United States)

    Solanki, Naimesh; Salvi, Ankita; Patki, Gaurav; Salim, Samina

    2017-07-01

    Persistent psychological stress often leads to anxiety disorders and depression. Benzodiazepines and selective serotonin reuptake inhibitors are popular treatment options but have limited efficacy, supporting the need for alternative treatment. Based on our recent preclinical work suggesting a causal link between neurobehavioral deficits and elevated oxidative stress, we hypothesized that interventions that mitigate oxidative stress can attenuate/overcome neurobehavioral deficits. Here, we employed the rat social defeat model of psychological stress to determine whether increasing antioxidant levels using grape powder would prevent and/or reverse social defeat-induced behavioral and cognitive deficits. Furthermore, a hippocampal-derived HT22 cell culture model of oxidative stress was employed to identify the individual beneficial constituent(s) of grape powder and the underlying mechanism(s) of action. Grape powder treatment prevented and reversed social defeat-induced behavioral and cognitive deficits and also decreased social defeat-induced increase in plasma corticosterone and 8-isoprostane (systemic and oxidative stress markers, respectively). And grape powder treatment replenished social defeat-induced depleted pool of key antioxidant enzymes glyoxalase-1, glutathione reducatse-1, and superoxide dismutase. Grape powder constituents, quercetin and resveratrol, were most effective in preventing oxidative stress-induced decreased cellular antioxidant capacity. Grape powder protected oxidative stress-induced cell death by preventing calcium influx, mitochondrial dysfunction, and release of cytochrome c. Grape powder treatment by increasing antioxidant pool and preventing cell damage and death prevented and reversed social defeat-induced behavioral and cognitive deficits in rats. Quercetin and resveratrol are the major contributors towards beneficial effects of grape powder.

  7. Adsorption-induced symmetry reduction of metal-phthalocyanines studied by vibrational spectroscopy

    Science.gov (United States)

    Sforzini, J.; Bocquet, F. C.; Tautz, F. S.

    2017-10-01

    We investigate the vibrational properties of Pt- and Pd-phthalocyanine (PtPc and PdPc) molecules on Ag(111) with high-resolution electron energy loss spectroscopy (HREELS). In the monolayer regime, both molecules exhibit long-range order. The vibrational spectra prove a flat adsorption geometry. The redshift of specific vibrational modes suggests a moderate interaction of the molecules with the substrate. The presence of asymmetric vibrational peaks indicates an interfacial dynamical charge transfer (IDCT). The molecular orbital that is involved in IDCT is the former Eg lowest unoccupied molecular orbital (LUMO) of the molecules that becomes partially occupied upon adsorption. A group-theoretical analysis of the IDCT modes, based on calculated vibrational frequencies and line shape fits, provides proof for the reduction of the symmetry of the molecule-substrate complex from fourfold D4 h to C2 v(σv) , Cs(σv) , or C2 and the ensuing lifting of the degeneracy of the former LUMO of the molecule. The vibration-based analysis of orbital degeneracies, as carried out here for PtPc/Ag(111) and PdPc/Ag(111), is particularly useful whenever the presence of multiple molecular in-plane orientations at the interface makes the analysis of orbital degeneracies with angle-resolved photoemission spectroscopy difficult.

  8. Vibration-induced nystagmus in patients with vestibular schwannoma: Characteristics and clinical implications.

    Science.gov (United States)

    Lee, Jeon Mi; Kim, Mi Joo; Kim, Jin Won; Shim, Dae Bo; Kim, Jinna; Kim, Sung Huhn

    2017-07-01

    To investigate the clinical significance of vibration-induced nystagmus (VIN) in unilateral vestibular asymmetry and vestibular schwannoma. Thirteen patients with vestibular schwannoma underwent the VIN test, in which stimulation was applied to the mastoid processes and sternocleidomastoid (SCM) muscles on the ipsilateral and contralateral sides of lesions. Preoperative VIN was measured, and changes in VIN were followed up for 6months after tumor removal. Significance of VIN was determined by evaluation of its sensitivity, correlation with vestibular function tests and tumor volume, and postoperative changes. The overall pre and postoperative sensitivities of VIN were 92.3% and 100%, respectively, considering stimulation at all four sites. Maximum slow-phase velocity (MSPV) of VIN was linearly correlated with caloric weakness and tumor volume, especially when stimulation was applied to the SCM muscle. Postoperative MSPV of VIN exhibited stronger linear correlation with postoperative changes in canal paresis value and inverse correlation with tumor size upon stimulation of the ipsilateral SCM muscle than upon stimulation of other sites. During the 6-month follow-up period, persistence of VIN without changes in MSPV was observed even after vestibular compensation. Evoking VIN by stimulation of the mastoid processes and SCM muscles is effective for detecting vestibular asymmetry. It could also help determine the degree of vestibular asymmetry and volume of vestibular schwannoma if stimulation is applied to the SCM muscle. The results of this study could provide clues for the basic application of VIN in patients with vestibular loss and vestibular schwannoma. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  9. (+)-Catechin protects dermal fibroblasts against oxidative stress-induced apoptosis

    Science.gov (United States)

    2014-01-01

    Background Oxidative stress has been suggested as a mechanism underlying skin aging, as it triggers apoptosis in various cell types, including fibroblasts, which play important roles in the preservation of healthy, youthful skin. Catechins, which are antioxidants contained in green tea, exert various actions such as anti-inflammatory, anti-bacterial, and anti-cancer actions. In this study, we investigated the effect of (+)-catechin on apoptosis induced by oxidative stress in fibroblasts. Methods Fibroblasts (NIH3T3) under oxidative stress induced by hydrogen peroxide (0.1 mM) were treated with either vehicle or (+)-catechin (0–100 μM). The effect of (+)-catechin on cell viability, apoptosis, phosphorylation of c-Jun terminal kinases (JNK) and p38, and activation of caspase-3 in fibroblasts under oxidative stress were evaluated. Results Hydrogen peroxide induced apoptotic cell death in fibroblasts, accompanied by induction of phosphorylation of JNK and p38 and activation of caspase-3. Pretreatment of the fibroblasts with (+)-catechin inhibited hydrogen peroxide-induced apoptosis and reduced phosphorylation of JNK and p38 and activation of caspase-3. Conclusion (+)-Catechin protects against oxidative stress-induced cell death in fibroblasts, possibly by inhibiting phosphorylation of p38 and JNK. These results suggest that (+)-catechin has potential as a therapeutic agent for the prevention of skin aging. PMID:24712558

  10. Influence of light-induced conical intersection on the photodissociation dynamics of D2(+) starting from individual vibrational levels.

    Science.gov (United States)

    Halász, Gábor J; Csehi, András; Vibók, Ágnes; Cederbaum, Lorenz S

    2014-12-26

    Previous works have shown that dressing of diatomic molecules by standing or by running laser waves gives rise to the appearance of so-called light-induced conical intersections (LICIs). Because of the strong nonadiabatic couplings, the existence of such LICIs may significantly change the dynamical properties of a molecular system. In our former paper (J. Phys. Chem. A 2013, 117, 8528), the photodissociation dynamics of the D(2)(+) molecule were studied in the LICI framework starting the initial vibrational nuclear wave packet from the superposition of all the vibrational states initially produced by ionizing D(2). The present work complements our previous investigation by letting the initial nuclear wave packets start from different individual vibrational levels of D(2)(+), in particular, above the energy of the LICI. The kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the photofragments are calculated and discussed. An interesting phenomenon has been found in the spectra of the photofragments. Applying the light-induced adiabatic picture supported by LICI, explanations are given for the unexpected structure of the spectra.

  11. Free vibration analysis of pre-stressed FGM Timoshenko beams under large transverse deflection by a variational method

    Directory of Open Access Journals (Sweden)

    Amlan Paul

    2016-06-01

    Full Text Available A theoretical study on free vibration behavior of pre-stressed functionally graded material (FGM beam is carried out. Power law variation of volume fraction along the thickness direction is considered. Geometric non-linearity is incorporated through von Kármán non-linear strain–displacement relationship. The governing equation for the static problem is obtained using minimum potential energy principle. The dynamic problem for the pre-stressed beam is formulated as an eigenvalue problem using Hamilton's principle. Three classical boundary conditions with immovable ends are considered for the present work, namely clamped–clamped, simply supported–simply supported and clamped–simply supported. Four different FGM beams, namely Stainless Steel–Silicon Nitride, Stainless Steel–Zirconia, Stainless Steel–Alumina and Titanium alloy–Zirconia, are considered for generation of results. Numerical results for non-dimensional frequency parameters of undeformed beam are presented. The results are presented in non-dimensional pressure-displacement plane for the static problem and in non-dimensional frequency-displacement plane for the dynamic problem. Comparative frequency-displacement plots are presented for different FGMs and also for different volume fraction indices.

  12. Comparison of finite-difference schemes for analysis of shells of revolution. [stress and free vibration analysis

    Science.gov (United States)

    Noor, A. K.; Stephens, W. B.

    1973-01-01

    Several finite difference schemes are applied to the stress and free vibration analysis of homogeneous isotropic and layered orthotropic shells of revolution. The study is based on a form of the Sanders-Budiansky first-approximation linear shell theory modified such that the effects of shear deformation and rotary inertia are included. A Fourier approach is used in which all the shell stress resultants and displacements are expanded in a Fourier series in the circumferential direction, and the governing equations reduce to ordinary differential equations in the meridional direction. While primary attention is given to finite difference schemes used in conjunction with first order differential equation formulation, comparison is made with finite difference schemes used with other formulations. These finite difference discretization models are compared with respect to simplicity of application, convergence characteristics, and computational efficiency. Numerical studies are presented for the effects of variations in shell geometry and lamination parameters on the accuracy and convergence of the solutions obtained by the different finite difference schemes. On the basis of the present study it is shown that the mixed finite difference scheme based on the first order differential equation formulation and two interlacing grids for the different fundamental unknowns combines a number of advantages over other finite difference schemes previously reported in the literature.

  13. Hypoxia-Induced Oxidative Stress Modulation with Physical Activity

    Science.gov (United States)

    Debevec, Tadej; Millet, Grégoire P.; Pialoux, Vincent

    2017-01-01

    Increased oxidative stress, defined as an imbalance between prooxidants and antioxidants, resulting in molecular damage and disruption of redox signaling, is associated with numerous pathophysiological processes and known to exacerbate chronic diseases. Prolonged systemic hypoxia, induced either by exposure to terrestrial altitude or a reduction in ambient O2 availability is known to elicit oxidative stress and thereby alter redox balance in healthy humans. The redox balance modulation is also highly dependent on the level of physical activity. For example, both high-intensity exercise and inactivity, representing the two ends of the physical activity spectrum, are known to promote oxidative stress. Numerous to-date studies indicate that hypoxia and exercise can exert additive influence upon redox balance alterations. However, recent evidence suggests that moderate physical activity can attenuate altitude/hypoxia-induced oxidative stress during long-term hypoxic exposure. The purpose of this review is to summarize recent findings on hypoxia-related oxidative stress modulation by different activity levels during prolonged hypoxic exposures and examine the potential mechanisms underlying the observed redox balance changes. The paper also explores the applicability of moderate activity as a strategy for attenuating hypoxia-related oxidative stress. Moreover, the potential of such moderate intensity activities used to counteract inactivity-related oxidative stress, often encountered in pathological, elderly and obese populations is also discussed. Finally, future research directions for investigating interactive effects of altitude/hypoxia and exercise on oxidative stress are proposed. PMID:28243207

  14. Hypoxia-Induced Oxidative Stress Modulation with Physical Activity.

    Science.gov (United States)

    Debevec, Tadej; Millet, Grégoire P; Pialoux, Vincent

    2017-01-01

    Increased oxidative stress, defined as an imbalance between prooxidants and antioxidants, resulting in molecular damage and disruption of redox signaling, is associated with numerous pathophysiological processes and known to exacerbate chronic diseases. Prolonged systemic hypoxia, induced either by exposure to terrestrial altitude or a reduction in ambient O2 availability is known to elicit oxidative stress and thereby alter redox balance in healthy humans. The redox balance modulation is also highly dependent on the level of physical activity. For example, both high-intensity exercise and inactivity, representing the two ends of the physical activity spectrum, are known to promote oxidative stress. Numerous to-date studies indicate that hypoxia and exercise can exert additive influence upon redox balance alterations. However, recent evidence suggests that moderate physical activity can attenuate altitude/hypoxia-induced oxidative stress during long-term hypoxic exposure. The purpose of this review is to summarize recent findings on hypoxia-related oxidative stress modulation by different activity levels during prolonged hypoxic exposures and examine the potential mechanisms underlying the observed redox balance changes. The paper also explores the applicability of moderate activity as a strategy for attenuating hypoxia-related oxidative stress. Moreover, the potential of such moderate intensity activities used to counteract inactivity-related oxidative stress, often encountered in pathological, elderly and obese populations is also discussed. Finally, future research directions for investigating interactive effects of altitude/hypoxia and exercise on oxidative stress are proposed.

  15. Evaluation of mechanical vibration effect on the residual stresses levels in steel welded joints using an Interface Matlab based on Norm API 579

    Directory of Open Access Journals (Sweden)

    R Rodrigues

    2016-10-01

    Full Text Available Nowadays with the high growth of petrochemical welding technology a great development due to high manufacturing offshore structures, storage tanks of petroleum, boilers and pressure vessels for refining plants have been done. Due to various metallurgical changes and restrictions to contraction and expansion undergone by materials when subjected to welding thermal cycle, internal stresses are generated in welded joint which are nominated residual stresses. It is generally undesirable because it can lead to several problems, such as cracks, cold stress fracture, stress corrosion, among others. Although several studies involving residual stresses have been developed in recent years, few information about the variation of the residual stresses level in welded joints when subjected to stress relief treatment by mechanical vibration have been done. Likewise, there are few information related to the comparison between the degree of efficiency by using the post-weld heat treatment and those treatment. Therefore, the goal of this work was to apply the relieve residual stresses treatment by mechanical vibration in steel welded joints used in oil industry, and compare the results with those obtained by post heat treatment and evaluate the efficiency level of this technique In addition, this works also hope to contribute for a better understanding of this technique and to find which parameters have a greater influence on the results.

  16. Acute stress impairs recognition for positive words--association with stress-induced cortisol secretion.

    Science.gov (United States)

    Domes, Gregor; Heinrichs, Markus; Rimmele, Ulrike; Reichwald, Ursula; Hautzinger, Martin

    2004-09-01

    Some studies suggest that stress-induced effects of cortisol on memory are modulated by the valence of the stimuli to be learned and retrieved. The present study investigated the effect of acute stress-induced cortisol secretion on acquisition and retrieval of pleasant, unpleasant and neutral words. Sixty healthy men were randomly assigned to one of the three experimental groups. Participants were either exposed to a standardized laboratory stressor (the Trier Social Stress Test) before learning a wordlist, or before retrieval, or were not stressed. Free recall and recognition were tested 24 h later. Free recall was not affected by stress exposure. For recognition, there was no main effect of the stressor, but a main effect of valence and a valence by group interaction emerged: recognition for positive words was significantly impaired when subjects were stressed before retrieval. In addition, a positive correlation between the cortisol response and errors of commission was found. The results suggest that acute stress impairs memory for positive stimuli and that stress-induced cortisol secretion interferes with accuracy of memory retrieval, i.e. the ability to discriminate true memories from false ones.

  17. Flow-induced vibration and flow characteristics prediction for a sliding roller gate by two-dimensional unsteady CFD simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nak-Geun; Lee, Kye-Bock [Chungbuk National University, Cheongju (Korea, Republic of); Cho, Yong [Korea Water Resources Corporation, Daejeon (Korea, Republic of)

    2017-07-15

    Numerical analysis on the flow induced vibration and flow characteristics in the water gate has been carried out by 2-dimensional unsteady CFD simulation when sea water flows into the port in the river. Effect of gate opening on the frequency and the mean velocity and the vortex shedding under the water gate were studied. The streamlines were compared for various gate openings. To get the frequency spectrum, Fourier transform should be performed. Spectral analysis of the excitation force signals permitted identification of the main characteristics of the interaction process. The results show that the sources of disturbed frequency are the vortex shedding from under the water gate. As the gate opening ratio increases, the predicted vibration frequency decreases. The bottom scouring occurs for large gate opening rather than smaller one. The unstable operation conditions can be estimated by using the CFD results and the Strouhal number results for various gate opening gaps.

  18. Flow-Induced Pulsation and Vibration in Hydroelectric Machinery Engineer’s Guidebook for Planning, Design and Troubleshooting

    CERN Document Server

    Dörfler, Peter; Coutu, André

    2013-01-01

    Since the 1970’s, an increasing amount of specialized research has focused on the problems created by instability of internal flow in hydroelectric power plants. However, progress in this field is hampered by the inter­disciplinary nature of the subject, between fluid mechanics, structural mechanics and hydraulic transients. Flow-induced Pulsation and Vibration in Hydroelectric Machinery provides a compact guidebook explaining the many different underlying physical mechanisms and their possible effects.   Typical phenomena are described to assist in the proper diagnosis of problems and various key strategies for solution are compared and considered with support from practical experience and real-life examples. The link between state-of the-art CFD computation and notorious practical problems is discussed  and quantitative data is provided on  normal levels of vibration and pulsation so realistic limits can be set for future projects. Current projects are also addressed as the possibilities and limitatio...

  19. Reflective polarization-modulation method of stress estimation using stress-induced birefringence

    Science.gov (United States)

    Kniazkov, A. V.

    2017-09-01

    This paper considers a scan method to measure mechanical stresses for a photoelastic material by the value of the reflection coefficient difference of orthogonal linearly polarized light waves. The results of the estimation of the stress state of a poly(methyl methacrylate) sample using the proposed reflective method are described. The dependencies of change induced by stress birefringence in the stressed sample from the displacement of the measuring beam transverse to the compression axis and along the axis are given. The case of almost normal incidence of light is considered.

  20. Intermittent Noise Induces Physiological Stress in a Coastal Marine Fish.

    Directory of Open Access Journals (Sweden)

    Tye A Nichols

    Full Text Available Anthropogenic noise in the ocean has increased substantially in recent decades, and motorized vessels produce what is likely the most common form of underwater noise pollution. Noise has the potential to induce physiological stress in marine fishes, which may have negative ecological consequences. In this study, physiological effects of increased noise (playback of boat noise recorded in the field on a coastal marine fish (the giant kelpfish, Heterostichus rostratus were investigated by measuring the stress responses (cortisol concentration of fish to increased noise of various temporal dynamics and noise levels. Giant kelpfish exhibited acute stress responses when exposed to intermittent noise, but not to continuous noise or control conditions (playback of recorded natural ambient sound. These results suggest that variability in the acoustic environment may be more important than the period of noise exposure for inducing stress in a marine fish, and provide information regarding noise levels at which physiological responses occur.

  1. Temperature rise and stress induced by microcracks in accelerating structures

    Directory of Open Access Journals (Sweden)

    W. Zhu

    2010-12-01

    Full Text Available The temperature rise and induced stress due to Ohmic heating in the vicinity of microcracks on the walls of high-gradient accelerating structures are considered. The temperature rise and induced stress depend on the orientation of the crack with respect to the rf magnetic field, the shape of the crack, and the power and duration of the rf pulse. Under certain conditions the presence of cracks can double the temperature rise over that of a smooth surface. Stress at the bottom of the cracks can be several times larger than that of the case when there are no cracks. We study these effects both analytically and by computer simulation. It is shown that the stress in cracks is maximal when the crack depth is on the order of the thermal penetration depth.

  2. Experimental study on cross-flow induced vibrations in heat exchanger tube bundle

    Science.gov (United States)

    Khushnood, Shahab; Nizam, Luqman Ahmad

    2017-03-01

    Vibration in heat exchangers is one of the main problems that the industry has faced over last few decades. Vibration phenomenon in heat exchangers is of major concern for designers and process engineers since it can lead to the tube damage, tube leakage, baffle damage, tube collision damage, fatigue, creep etc. In the present study, vibration response is analyzed on single tube located in the centre of the tube bundle having parallel triangular arrangement (60°) with P/ D ratio of 1.44. The experiment is performed for two different flow conditions. This kind of experiment has not been reported in the literature. Under the first condition, the tube vibration response is analyzed when there is no internal flow in the tube and under the second condition, the response is analyzed when the internal tube flow is maintained at a constant value of 0.1 m/s. The free stream shell side velocity ranges from 0.8 m/s to 1.3 m/s, the reduced gap velocity varies from 1.80 to 2.66 and the Reynolds number varies from 44500 to 66000. It is observed that the internal tube flow results in larger vibration amplitudes for the tube than that without internal tube flow. It is also established that over the current range of shell side flow velocity, the turbulence is the dominant excitation mechanism for producing vibration in the tube since the amplitude varies directly with the increase in the shell side velocity. Damping has no significant effect on the vibration behavior of the tube for the current velocity range.

  3. Oxidative stress and histopathological changes induced by ...

    African Journals Online (AJOL)

    was marked by the enhanced TBARS (thiobarbituric acid reactive substances) production in the liver and kidney of. MT treated rats indicating MT pro-oxidant effects to alter membrane integrity and fluidity. Many xenobiotics, such as pesticides, are known to induce oxidative damage through ROS generation and can alter.

  4. Vibration Characteristics Induced by Cavitation in a Centrifugal Pump with Slope Volute

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2015-01-01

    Full Text Available Cavitation is one of the instability sources in centrifugal pump, which would cause some unexpected results. The goal of this paper was to analyze the influence of cavitation process on different frequency bands in a centrifugal pump with slope volute. And special attention was paid to low frequency signals, which were often filtered in the reported researches. Results show that at noncavitation condition, vibration level is closely related to flow structure interior pump. At partial flow rates, especially low flow rates, vibration level increases rapidly with the onset of rotating stall. At cavitation condition, it is proved that cavitation process has a significant impact on low frequency signals. With cavitation number decreasing, vibration level first rises to a local maximum, then it drops to a local minimum, and finally it rises again. At different flow rates, vibration trends in variable frequency bands differ obviously. Critical point inferred from vibration level is much larger than that from 3% head drop, which indicates that cavitation occurs much earlier than that reflected in head curve. Also, it is noted that high frequency signals almost increase simultaneously with cavitation occurring, which can be used to detect cavitation in centrifugal pump.

  5. Gravity-induced stresses near a vertical cliff

    Science.gov (United States)

    Savage, W.Z.

    1993-01-01

    The exact solution for gravity-induced stresses beneath a vertical cliff presented here has application to the design of cut slopes in rock, compares favorably with published photoelastic and finite-element results for this problem, and satisfies the condition that shear and normal stresses vanish on the ground surface, except at the bottom corner where stress concentrations exist. The solution predicts that horizontal stresses are tensile away from the bottom of the cliff-effects caused by movement below the cliff in response to the gravity loading of the cliff. Also, it is shown that along the top of the cliff normal stresses reduce to those predicted for laterally constrained flat-lying topography. ?? 1993.

  6. Implication of Snail in Metabolic Stress-Induced Necrosis

    Science.gov (United States)

    Ju, Min Kyung; Moon, Ji Young; Park, Hye Gyeong; Yoo, Mi-Ae; Choi, Byung Tae; Yook, Jong In; Lim, Sung-Chul; Han, Song Iy; Kang, Ho Sung

    2011-01-01

    Background Necrosis, a type of cell death accompanied by the rupture of the plasma membrane, promotes tumor progression and aggressiveness by releasing the pro-inflammatory and angiogenic cytokine high mobility group box 1. It is commonly found in the core region of solid tumors due to hypoxia and glucose depletion (GD) resulting from insufficient vascularization. Thus, metabolic stress-induced necrosis has important clinical implications for tumor development; however, its regulatory mechanisms have been poorly investigated. Methodology/Principal Findings Here, we show that the transcription factor Snail, a key regulator of epithelial-mesenchymal transition, is induced in a reactive oxygen species (ROS)-dependent manner in both two-dimensional culture of cancer cells, including A549, HepG2, and MDA-MB-231, in response to GD and the inner regions of a multicellular tumor spheroid system, an in vitro model of solid tumors and of human tumors. Snail short hairpin (sh) RNA inhibited metabolic stress-induced necrosis in two-dimensional cell culture and in multicellular tumor spheroid system. Snail shRNA-mediated necrosis inhibition appeared to be linked to its ability to suppress metabolic stress-induced mitochondrial ROS production, loss of mitochondrial membrane potential, and mitochondrial permeability transition, which are the primary events that trigger necrosis. Conclusions/Significance Taken together, our findings demonstrate that Snail is implicated in metabolic stress-induced necrosis, providing a new function for Snail in tumor progression. PMID:21448462

  7. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    Science.gov (United States)

    Wang, Liying

    2013-01-01

    The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NP-induced injury can be developed. PMID:24027766

  8. An Analytical Approach on Thermally Induced Vibrations of Nonhomogeneous Tapered Plate

    Directory of Open Access Journals (Sweden)

    Anupam Khanna

    2013-01-01

    Full Text Available A mathematical model to control the vibrations of a rectangular plate is constructed with an aim to assist engineers in designing and fabrication of various structures used in the field of science and technology, mostly used in satellite and aeronautical engineering. The present study is related to the analysis of free vibrations of nonhomogeneous rectangular plate clamped at all the four edges. Authors studied the bilinear effect of thickness as well as temperature variations in both and directions. Variation in Poisson's ratio is also considered linearly in -direction due to nonhomogeneity. Rayleigh-Ritz method is used to analyze the frequencies for the first two modes of vibrations for different values of thermal gradient, nonhomogeneity constant, taper constants and aspect ratio. All the numerical computations have been performed for an alloy of aluminum, that is, duralumin. All the results are presented in the form of graphs.

  9. Moisture-induced stresses in glulam frames

    DEFF Research Database (Denmark)

    Ormarsson, Sigurdur; Gislason, Oskar V

    2016-01-01

    Wood is a hygroscopic and moisture-sensitive material that seeks to achieve equilibrium moisture content (EMC) with its surrounding environment. For softwood timber structures exposed to variations in climate throughout their service life, this behaviour results in variable moisture-content gradi......Wood is a hygroscopic and moisture-sensitive material that seeks to achieve equilibrium moisture content (EMC) with its surrounding environment. For softwood timber structures exposed to variations in climate throughout their service life, this behaviour results in variable moisture...... is presented. A two-dimensional transient, non-linear moisture transport model for wood is also developed and linked with this beam model. The combined models are used to study the long-term deformations and stresses in a curved frame structure exposed to both mechanical loading and cyclic climate conditions...

  10. Vibration-induced coherence enhancement of the performance of a biological quantum heat engine.

    Science.gov (United States)

    Chen, Hong-Bin; Chiu, Pin-Yi; Chen, Yueh-Nan

    2016-11-01

    Photosynthesis has been a long-standing research interest due to its fundamental importance. Recently, studies on photosynthesis processes also have inspired attention from a thermodynamical aspect when considering photosynthetic apparatuses as biological quantum heat engines. Quantum coherence is shown to play a crucial role in enhancing the performance of these quantum heat engines. Based on the experimentally reported structure, we propose a quantum heat engine model with a non-Markovian vibrational mode. We show that one can obtain a performance enhancement easily for a wide range of parameters in the presence of the vibrational mode. Our results provide insights into the photosynthetic processes and a design principle mimicking natural organisms.

  11. Vibration-induced coherence enhances the performance of a biological quantum heat engine

    CERN Document Server

    Chen, Hong-Bin; Chen, Yueh-Nan

    2016-01-01

    Photosynthesis has been the long-standing research interest due to its fundamental importance. Recently, studies on photosynthesis processes also inspire attention from thermodynamical aspect when considering photosynthetic apparatuses as biological quantum heat engines. Quantum coherence is shown to play a crucial role in enhancing the performance of these quantum heat engines. Based on the experimentally reported structure, we propose a quantum heat engine model with a non-Markovian vibrational mode. We show that one can obtain a performance enhancement easily for a wide range of parameters in the presence of the vibrational mode. Our results suggest new insights into the photosynthetic processes and a design principle mimicking natural organisms.

  12. Simulation of Transient Nonlinear Friction-Induced Vibrations Using Complex Interface Modes: Application to the Prediction of Squeal Events

    Directory of Open Access Journals (Sweden)

    J.-J. Sinou

    2017-01-01

    Full Text Available During the past decades, the problem of friction-induced vibration and noise has been the subject of a huge amount of works. Various numerical simulations with finite elements models have been largely investigated to predict squeal events. Although a nonlinear analysis is more predictive than Complex Eigenvalues Analysis, one of the main drawbacks of the time analysis is the need of large computational efforts. In view of the complexity of the subject, this approach appears still computationally too expensive to be used in industry for finite element models. In this study, the potential of a new reduced model based on a double modal synthesis (i.e., a classical modal reduction via Craig and Bampton plus a condensation at the frictional interface based on complex modes for the prediction of self-excited vibrations of brake squeal is discussed. The effectiveness of the proposed modal reduction is tested on a finite element model of a simplified brake system. It will be shown that numerical results of times analysis by applying the proposed reduction correlate well with those of the nonlinear analysis based on a reference model, hence demonstrating the potential of using adapted modal reductions to predict the squeal propensity and to estimate self-excited vibrations and noise.

  13. Numerical Research about Influence of Blade Outlet Angle on Flow-Induced Noise and Vibration for Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Ailing Yang

    2014-03-01

    Full Text Available A hybrid numerical method was used to calculate the flow-induced noise and vibration of the centrifugal pump in the paper. The unsteady flows inside the centrifugal pumps with different blade outlet angles were simulated firstly. The unsteady pressure on the inner surface of the volute and the unsteady force applied on the impeller were analyzed. Then the vibration of the volute and sound field were calculated based on an acoustic-vibro-coupling method. The results show that the pump head has increased 7% while the hydraulic efficiency decreased 11.75% as blade outlet angles increased from 18° to 39°. The amplitude of pressure fluctuation at the first blade passing frequency has decreased but increased at the second-order blade passing frequency as the angle growing. The total fluctuation power near volute tongue goes up about 12% every 3° increment of blade outlet angle. The results also show that vibrating-velocity of the volute at second-order blade passing frequency is much higher than at other frequencies, and the velocity increases rapidly as blade outlet angle varies from 18° to 39°. At the same time, the sound pressure level outside the pump has increased about 8.6 dB when the angle increased from 18° to 39°.

  14. An Intelligent Optimization Method for Vortex-Induced Vibration Reducing and Performance Improving in a Large Francis Turbine

    Directory of Open Access Journals (Sweden)

    Xuanlin Peng

    2017-11-01

    Full Text Available In this paper, a new methodology is proposed to reduce the vortex-induced vibration (VIV and improve the performance of the stay vane in a 200-MW Francis turbine. The process can be divided into two parts. Firstly, a diagnosis method for stay vane vibration based on field experiments and a finite element method (FEM is presented. It is found that the resonance between the Kármán vortex and the stay vane is the main cause for the undesired vibration. Then, we focus on establishing an intelligent optimization model of the stay vane’s trailing edge profile. To this end, an approach combining factorial experiments, extreme learning machine (ELM and particle swarm optimization (PSO is implemented. Three kinds of improved profiles of the stay vane are proposed and compared. Finally, the profile with a Donaldson trailing edge is adopted as the best solution for the stay vane, and verifications such as computational fluid dynamics (CFD simulations, structural analysis and fatigue analysis are performed to validate the optimized geometry.

  15. Study on the Effect and Mechanism of Aerodynamic Measures for the Vortex-Induced Vibration of Separate Pairs of Box Girders in Cable-Stayed Bridges

    Directory of Open Access Journals (Sweden)

    Han Xin He

    2015-01-01

    Full Text Available Although not always resulting in catastrophic failures, vortex-induced vibration (VIV response can seriously impact the fatigue life and functionality of bridges, especially for separate pairs of box girders in cable-stayed bridges. This study investigates the effects of three aerodynamic measures: grating, inclined web plate, and the baffles on separated box girders in the cable-stayed bridges. The experimental result indicates that the grating of different opening ratios can control the vortex-induced vibration effectively, and the optimized grating opening ratio set in this paper is 40%. Increasing the angle of inclined web plate has a great control on mitigation of the vortex-induced vibration. However, there is an optimum angle where the amplitude of vortex-induced vibration is the smallest at low wind speed. The amplitude of vortex-induced vibration becomes larger with the increase of the web inclined angle that exceeds the optimum angle. Comparatively, the baffles installed on both sides of the inclined webs are more effective to restrain the vortex-induced resonance. The Computational Fluent Dynamics (CFD software is utilized to investigate the mechanism of the experimental results.

  16. Vortex-induced vibrations of a flexibly-mounted inclined cylinder

    Science.gov (United States)

    Jain, Anil; Modarres-Sadeghi, Yahya

    2013-11-01

    The majority of studies on vortex-induced vibrations of a flexibly-mounted rigid cylinder are for the cases where the flow direction is perpendicular to the long axis of the structure. However, in many engineering applications, such as cable stays in bridges and mooring lines of floating offshore wind turbines, the flow direction may not be perpendicular to the structure. To understand the vortex shedding behind a fixed inclined cylinder, the Independence Principle (IP) has been used. The IP assumes that an inclined cylinder behaves similarly to a normal-incidence case, if only the component of the free stream velocity normal to the cylinder axis is considered. The IP neglects the effect of the axial component of the flow, which seems reasonable for small angles of inclination, but not for large angles. In the present study, a series of experiments have been conducted on a flexibly-mounted rigid cylinder placed inclined to the oncoming flow with various angles of inclination (0°<θ<75°) in a range of Reynolds numbers from 500 to 4000 to investigate how the angle of inclination affects VIV. A rigid cylinder was mounted on springs, and air bearings were used to reduce the structural damping of the system. The system was placed in the test-section of a recirculating water tunnel and the crossflow displacements were measured at each flow velocity. Even at high angles of inclination, large-amplitude oscillations were observed. As the angle of inclination was increased, the lock-in range (the range of reduced flow velocities for which the cylinder oscillates with a large amplitude) started at a higher reduced velocity. When only the normal component of the oncoming flow was considered, the onset of lock-in was observed to be at the same normalized flow velocity for all angles of inclination except for 75°. However, the width of the lock-in region, its pattern, the maximum amplitude of oscillations and its corresponding normalized reduced velocity were not following

  17. Combined experimental and numerical investigation of energy harness utilizing vortex induced vibration over half cylinder using piezoelectric beams

    Science.gov (United States)

    Ahmed, Md. Tusher; Hossain, Md. Tanver; Rahman, Md. Ashiqur

    2017-06-01

    Energy harvesting technology has the ability to create self-powered electronic systems that do not rely on battery power for their operation. Wind energy can be converted into electricity via a piezoelectric transducer during the air flow over a cylinder. The vortex-induced vibration over the cylinder causes the piezoelectric beam to vibrate. Thus useful electric energy at the range 0.2-0.3V is found which can be useful for self-powering small electronic devices. In the present study, prototypes of micro-energy harvester with a shape of 65 mm × 37 mm × 0.4 mm are developed and tested for airflow over D-shaped bluff body for diameters of 15, 20 and 28mm in an experimental setup consisting of a long wind tunnel of 57cm × 57cm with variable speeds of the motor for different flow velocities and the experimental setup is connected at the downstream where flow velocity is the maximum. Experimental results show that the velocity and induced voltage follows a regular linear pattern. A maximum electrical potential of 140 mV for velocity of 1.1 ms-1 at a bluff body diameter of 15 mm is observed in the energy harvester that can be applied in many practical cases for self-powering electronic devices. The simulation of this energy harvesting phenomena is then simulated using COMSOLE multi-physics. Diameter of the bluff bodies as well as flow velocity and size of cantilever beam are varied and the experimental findings are found to be in good agreement with the simulated ones. The simulations along with the experimental data show the possibility of generating electricity from vortex induced vibration and can be applied in many practical cases for self-powering electronic devices.

  18. Electric field dependent structural and vibrational properties of the Si(100)-H(2 x 1) surface and its implications for STM induced hydrogen desorption

    DEFF Research Database (Denmark)

    Stokbro, Kurt

    1999-01-01

    We report a first principles study of the structure and the vibrational properties of the Si(100)-H(2 x 1) surface in an electric field. The calculated vibrational parameters are used to model the vibrational modes in the presence of the electric field corresponding to a realistic scanning...... at room temperature). We calculate the implications for current induced desorption of H using a recently developed first principles model of electron inelastic scattering. The calculations show that inelastic scattering events with energy transfer n (h) over bar omega, where n>1, play an important role...

  19. Field measurement of wind pressure and wind-induced vibration of large-span spatial cable-truss system under strong wind or typhoon

    Directory of Open Access Journals (Sweden)

    ZHANG Zhihong

    2013-10-01

    Full Text Available In order to ensure wind-resistance safety of large-span pre-stressed flexible system in southeast coast area of China,and to prepare something for revising of current codes of practice or technical standards,the present paper conducts field measurement of wind pressure and wind-induced vibration of a practical and typical large-span spatial cable-truss system-lunar stadium in Yueqing city.Wind loading and wind effects on full-scale structure under strong wind or typhoon in real architectural environment can be obtained directly and effectively.Field measurement is the best way to investigate the wind loading property,wind effects,and wind-structure interactions of large-span flexible system.Measured data will be highly valuable for scientific research and practical design.On the other hand,it also provides the basis of wind-resistance safety design of this kind of tension structures.If any creative development,it would dramatically improve the research level of large-span pre-stressed flexible system in our country.

  20. Oxidative stress induces mitochondrial fragmentation in frataxin-deficient cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sophie [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); ED515 UPMC, 4 place Jussieu 75005 Paris (France); Sliwa, Dominika [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); Rustin, Pierre [Inserm, U676, Physiopathology and Therapy of Mitochondrial Disease Laboratory, 75019 Paris (France); Universite Paris-Diderot, Faculte de Medecine Denis Diderot, IFR02 Paris (France); Camadro, Jean-Michel [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); Santos, Renata, E-mail: santos.renata@ijm.univ-paris-diderot.fr [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Yeast frataxin-deficiency leads to increased proportion of fragmented mitochondria. Black-Right-Pointing-Pointer Oxidative stress induces complete mitochondrial fragmentation in {Delta}yfh1 cells. Black-Right-Pointing-Pointer Oxidative stress increases mitochondrial fragmentation in patient fibroblasts. Black-Right-Pointing-Pointer Inhibition of mitochondrial fission in {Delta}yfh1 induces oxidative stress resistance. -- Abstract: Friedreich ataxia (FA) is the most common recessive neurodegenerative disease. It is caused by deficiency in mitochondrial frataxin, which participates in iron-sulfur cluster assembly. Yeast cells lacking frataxin ({Delta}yfh1 mutant) showed an increased proportion of fragmented mitochondria compared to wild-type. In addition, oxidative stress induced complete fragmentation of mitochondria in {Delta}yfh1 cells. Genetically controlled inhibition of mitochondrial fission in these cells led to increased resistance to oxidative stress. Here we present evidence that in yeast frataxin-deficiency interferes with mitochondrial dynamics, which might therefore be relevant for the pathophysiology of FA.

  1. Influence of treatment by vibration in residual stress generated in the laser welding of HSLA and IF steels; Influencia do tratamento de vibracao nas tensoes residuais geradas na soldagem a laser de acos ARBL e IF

    Energy Technology Data Exchange (ETDEWEB)

    Chuvas, T.C.; Fonseca, M.P. Cindra, E-mail: chuvas@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Engenharia Mecanica; Castello, D.A. [Universidade Federal do Rio de Janeiro (DEM/UFRJ), RJ (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    The stress relieving treatment by vibration is a new technology under development, which has many advantages over thermal methods. In this work was analyzed the surface residual stress generated in the laser welding of biphasic HSLA and IF steels, both used in the automotive industry. Residual stresses were measured by X-ray diffraction, by the sen{sup 2} {Psi} method. Residual stresses generated in the welding of the samples were tensile at all points measured. After welding, the samples were submitted to the mechanical vibration treatment. Some samples presented a significant reduction in the stress values. The welded joints were also characterized by optical microscopy. (author)

  2. Crowd-induced vibrations of a steel footbridge in Reykjavík

    DEFF Research Database (Denmark)

    Ingólfsson, Einar Thór; Gudmundsson, G. V.; Živanović, S.

    2012-01-01

    in relation to the results obtained from a controlled crowd test on a steel footbridge in Reykjavik, Iceland. A systematic quantification of the measured vibration response is carried out and the results are presented statistically through their probability distributions. Finally, testimonies from...

  3. Mitigation of Traffic-Induced Ground Vibration by Inclined Wave Barriers

    DEFF Research Database (Denmark)

    Andersen, Lars; Augustesen, Anders Hust

    2009-01-01

    Double sheet pile walls can be used as wave barriers in order to mitigate ground vibrations from railways. The present analysis concerns the efficiency of such barriers, especially with regard to the influence of the barrier inclination and the backfill between the walls. Thus, the screening...

  4. Water stress induced changes in antioxidant enzymes, membrane ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-12-01

    Dec 1, 2009 ... Water stress induced changes in antioxidant enzymes membrane stablity index and seed protein profiling of four different wheat (Triticum aestivum L.) accessions (011251, 011417, 011320 and 011393) were determined in a pot study under natural condition during the wheat-growing season 2005 and.

  5. Alleviation of oxidative stress induced by spider mite invasion ...

    African Journals Online (AJOL)

    Spider mite invasion induces oxidative stress on bean plants and increased soluble sugars, phenole, proline and peroxidase activity, but decreased catalase activity and ascorbic acid and carotenoid concentration. Application of elicitors significantly enhanced spider mite tolerance by decreasing hydrogen peroxide, ...

  6. Neuromodulator and Emotion Biomarker for Stress Induced Mental Disorders

    Directory of Open Access Journals (Sweden)

    Simeng Gu

    2016-01-01

    Full Text Available Affective disorders are a leading cause of disabilities worldwide, and the etiology of these many affective disorders such as depression and posttraumatic stress disorder is due to hormone changes, which includes hypothalamus-pituitary-adrenal axis in the peripheral nervous system and neuromodulators in the central nervous system. Consistent with pharmacological studies indicating that medical treatment acts by increasing the concentration of catecholamine, the locus coeruleus (LC/norepinephrine (NE system is regarded as a critical part of the central “stress circuitry,” whose major function is to induce “fight or flight” behavior and fear and anger emotion. Despite the intensive studies, there is still controversy about NE with fear and anger. For example, the rats with LC ablation were more reluctant to leave a familiar place and took longer to consume the food pellets in an unfamiliar place (neophobia, i.e., fear in response to novelty. The reason for this discrepancy might be that NE is not only for flight (fear, but also for fight (anger. Here, we try to review recent literatures about NE with stress induced emotions and their relations with mental disorders. We propose that stress induced NE release can induce both fear and anger. “Adrenaline rush or norepinephrine rush” and fear and anger emotion might act as biomarkers for mental disorders.

  7. Evaluation of cytotoxicity and oxidative stress induced by alcoholic ...

    African Journals Online (AJOL)

    Evaluation of cytotoxicity and oxidative stress induced by alcoholic extract and oil of Lepidium Sativum seeds in human liver cell line HepG2. ... The results show that LSA and LSO reduced cell viability, and altered the cellular morphology in dose dependent manner. Concentrations (100 to 1000 μg/ml) of LSA and LSO were ...

  8. cyclooxygenase inhibitors and the exercise-induced stress response

    African Journals Online (AJOL)

    pain, trauma and exercise, stimulate prostaglandin synthesis. The mechanisms underlying this stimulation usually ... sor-induced prostaglandin synthesis, in turn, initiates and modulates many aspects of the stress .... known.9 The best known is aspirin, synthesised from salicylic acid, which inhibits the activity of COX-1 by ...

  9. extract attenuates MPTP-induced oxidative stress and behavioral

    African Journals Online (AJOL)

    Purpose: To evaluate the protective effects of Cuminum cyminum Linn (Apiaceae, CCY) against 1- methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced oxidative stress and behavioral impairments in mouse model of Parkinson's disease (PD). Methods: MPTP-intoxicated mice model of PD was used for evaluating ...

  10. Severity of Stress Induced Factors Among Students in Tertiary ...

    African Journals Online (AJOL)

    ... stress induced factors were ranked as highly experienced-while physical and health, personal psychological, administrative, future Concerns and moral and religious stressors were ranked as lowly experienced. It was therefore suggested that counselling centers be established in Nigerian institutions of higher learning to ...

  11. Work-Induced Stress and Its Influence on Organizational ...

    African Journals Online (AJOL)

    The study examined work induced stress and its relationship to Organizational Effectiveness and Productivity amongst Nigerian Employees. Employees of Nigerian Television Authority and Nigerian Immigration Services were sampled in this study to observe how workplace has interfered with their inputs and organizational ...

  12. Effect of stress-induced grain growth during room temperature ...

    Indian Academy of Sciences (India)

    Administrator

    Effect of stress-induced grain growth during room temperature tensile deformation on ductility in nanocrystalline metals. WEICHANG XU, PINQIANG DAI* and XIAOLEI WU. †. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China. †. State Key Laboratory of Nonlinear Mechanics, Institute ...

  13. Palladium induced oxidative stress and cell death in normal ...

    African Journals Online (AJOL)

    Pretreatment of hepatocytes with ROS scavengers and MPT pore sealing agents reduced cell death which explains the role of oxidative stress and mitochondrial pathway of ROS formation in Pd hepatocytes cell toxicity. Overall, the results have distinctly determined the mechanism by which Pd-induced toxicity in the ...

  14. Sodium nitroprusside (SNP) alleviates the oxidative stress induced ...

    African Journals Online (AJOL)

    Oxidative damage is often induced by abiotic stress, nitric oxide (NO) is considered as a functional molecule in modulating antioxidant metabolism of plants. In the present study, effects of sodium nitroprusside (SNP), a NO donor, on the phenotype, antioxidant capacity and chloroplast ultrastructure of cucumber leaves were ...

  15. Ovariectomy exacerbates oxidative stress and cardiopathy induced by adriamycin.

    Science.gov (United States)

    Muñoz-Castañeda, Juan Rafael; Muntané, Jordi; Herencia, Carmen; Muñoz, Maria C; Bujalance, Inmaculada; Montilla, Pedro; Túnez, Issac

    2006-02-01

    Ovarian hormone depletion in ovariectomized experimental animals is a useful model with which to study the physiopathological consequences of menopause in women. It has been suggested that menopause is a risk factor for the induction of several cardiovascular disorders. In the present study we analyzed the effects of ovarian hormone depletion by ovariectomy (OVX) in a model of oxidative stress and cardiopathy induced by adriamycin (AD). To evaluate these effects, we measured parameters related to cardiac damage (creatinine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase) and oxidative stress (malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, reduced glutathione, nitric oxide and carbonyl proteins) in cardiac tissue and erythrocytes. OVX was found to alter all markers of oxidative stress and cell damage in cardiac tissue. Similarly, the OVX-derived loss of ovarian hormones enhanced cardiac damage and oxidative stress induced by AD. Our results suggest that antioxidant status in cardiac tissue and erythrocytes is seriously compromised by OVX during the cardiomyopathy induced by AD in experimental animals. In conclusion, the absence of hormones caused by OVX or menopause may induce or accelerate pre-existing cardiovascular dysfunctions.

  16. Vibration analysis of a rotating functionally graded tapered microbeam based on the modified couple stress theory by DQEM

    Science.gov (United States)

    Ghadiri, Majid; Shafiei, Navvab; Alireza Mousavi, S.

    2016-09-01

    Due to having difficulty in solving governing nonlinear differential equations of a non-uniform microbeam, a few numbers of authors have studied such fields. In the present study, for the first time, the size-dependent vibration behavior of a rotating functionally graded (FG) tapered microbeam based on the modified couple stress theory is investigated using differential quadrature element method (DQEM). It is assumed that physical and mechanical properties of the FG microbeam are varying along the thickness that will be defined as a power law equation. The governing equations are determined using Hamilton's principle, and DQEM is presented to obtain the results for cantilever and propped cantilever boundary conditions. The accuracy and validity of the results are shown in several numerical examples. In order to display the influence of size on the first two natural frequencies and consequently changing of some important microbeam parameters such as material length scale, rate of cross section, angular velocity and gradient index of the FG material, several diagrams and tables are represented. The results of this article can be used in designing and optimizing elastic and rotary-type micro-electro-mechanical systems like micro-motors and micro-robots including rotating parts.

  17. Fluid Production Induced Stress Analysis Surrounding an Elliptic Fracture

    Science.gov (United States)

    Pandit, Harshad Rajendra

    Hydraulic fracturing is an effective technique used in well stimulation to increase petroleum well production. A combination of multi-stage hydraulic fracturing and horizontal drilling has led to the recent boom in shale gas production which has changed the energy landscape of North America. During the fracking process, highly pressurized mixture of water and proppants (sand and chemicals) is injected into to a crack, which fractures the surrounding rock structure and proppants help in keeping the fracture open. Over a longer period, however, these fractures tend to close due to the difference between the compressive stress exerted by the reservoir on the fracture and the fluid pressure inside the fracture. During production, fluid pressure inside the fracture is reduced further which can accelerate the closure of a fracture. In this thesis, we study the stress distribution around a hydraulic fracture caused by fluid production. It is shown that fluid flow can induce a very high hoop stress near the fracture tip. As the pressure gradient increases stress concentration increases. If a fracture is very thin, the flow induced stress along the fracture decreases, but the stress concentration at the fracture tip increases and become unbounded for an infinitely thin fracture. The result from the present study can be used for studying the fracture closure problem, and ultimately this in turn can lead to the development of better proppants so that prolific well production can be sustained for a long period of time.

  18. Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

    Science.gov (United States)

    Riad, Sandra; Bougherara, Habiba

    2015-01-01

    Cisplatin (CisPt) is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2) cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death). Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death). PMID:25685789

  19. Diaphragmatic Breathing Reduces Exercise-Induced Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Daniele Martarelli

    2011-01-01

    Full Text Available Diaphragmatic breathing is relaxing and therapeutic, reduces stress, and is a fundamental procedure of Pranayama Yoga, Zen, transcendental meditation and other meditation practices. Analysis of oxidative stress levels in people who meditate indicated that meditation correlates with lower oxidative stress levels, lower cortisol levels and higher melatonin levels. It is known that cortisol inhibits enzymes responsible for the antioxidant activity of cells and that melatonin is a strong antioxidant; therefore, in this study, we investigated the effects of diaphragmatic breathing on exercise-induced oxidative stress and the putative role of cortisol and melatonin hormones in this stress pathway. We monitored 16 athletes during an exhaustive training session. After the exercise, athletes were divided in two equivalent groups of eight subjects. Subjects of the studied group spent 1 h relaxing performing diaphragmatic breathing and concentrating on their breath in a quiet place. The other eight subjects, representing the control group, spent the same time sitting in an equivalent quite place. Results demonstrate that relaxation induced by diaphragmatic breathing increases the antioxidant defense status in athletes after exhaustive exercise. These effects correlate with the concomitant decrease in cortisol and the increase in melatonin. The consequence is a lower level of oxidative stress, which suggests that an appropriate diaphragmatic breathing could protect athletes from long-term adverse effects of free radicals.

  20. Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

    Directory of Open Access Journals (Sweden)

    Laila Ziko

    2015-01-01

    Full Text Available Cisplatin (CisPt is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2 cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death. Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death.

  1. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  2. Modulation of Hypercholesterolemia-Induced Oxidative/Nitrative Stress in the Heart

    National Research Council Canada - National Science Library

    Csonka, Csaba; Sárközy, Márta; Pipicz, Márton; Dux, László; Csont, Tamás

    2016-01-01

    ..., and diminished stress adaptation. Both preclinical and clinical studies suggested that elevated oxidative and/or nitrative stress plays a key role in cardiac complications induced by hypercholesterolemia...

  3. Activation of the hypothalamic-pituitary-adrenal stress axis induces cellular oxidative stress

    Directory of Open Access Journals (Sweden)

    Jereme G. Spiers

    2015-01-01

    Full Text Available Glucocorticoids released from the adrenal gland in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA axis induce activity in the cellular reduction-oxidation (redox system. The redox system is a ubiquitous chemical mechanism allowing the transfer of electrons between donor/acceptors and target molecules during oxidative phosphorylation while simultaneously maintaining the overall cellular environment in a reduced state. The objective of this review is to present an overview of the current literature discussing the link between HPA axis-derived glucocorticoids and increased oxidative stress, particularly focussing on the redox changes observed in the hippocampus following glucocorticoid exposure.

  4. Metformin attenuates ER stress-induced mitochondrial dysfunction.

    Science.gov (United States)

    Chen, Qun; Thompson, Jeremy; Hu, Ying; Das, Anindita; Lesnefsky, Edward J

    2017-12-01

    Endoplasmic reticulum (ER) stress, a disturbance of the ER function, contributes to cardiac injury. ER and mitochondria are closely connected organelles within cells. ER stress contributes to mitochondrial dysfunction, which is a key factor to increase cardiac injury. Metformin, a traditional anti-diabetic drug, decreases cardiac injury during ischemia-reperfusion. Metformin also inhibits ER stress in cultured cells. We hypothesized that metformin can attenuate the ER stress-induced mitochondrial dysfunction and subsequent cardiac injury. Thapsigargin (THAP, 3 mg/kg) was used to induce ER stress in C57BL/6 mice. Cell injury and mitochondrial function were evaluated in the mouse heart 48 hours after 1-time THAP treatment. Metformin was dissolved in drinking water (0.5 g/250 ml) and fed to mice for 7 days before THAP injection. Metformin feeding continued after THAP treatment. THAP treatment increased apoptosis in mouse myocardium compared to control. THAP also led to decreased oxidative phosphorylation in heart mitochondria-oxidizing complex I substrates. THAP decreased the calcium retention capacity, indicating that ER stress sensitizes mitochondria to mitochondrial permeability transition pore opening. The cytosolic C/EBP homologous protein (CHOP) content was markedly increased in THAP-treated hearts compared to control, particularly in the nucleus. Metformin prevented the THAP-induced mitochondrial dysfunction and reduced CHOP content in cytosol and nucleus. Thus, metformin reduces cardiac injury during ER stress through the protection of cardiac mitochondria and attenuation of CHOP expression. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Intense and exhaustive exercise induce oxidative stress in skeletal muscle

    Directory of Open Access Journals (Sweden)

    T Thirumalai

    2011-03-01

    Full Text Available Objective: To assess the oxidative stress and antioxidant defense system in the skeletal muscle of male albino rats subjected to strenuous exercise programme. Methods: Wistar strain albino rats were subjected to exhaustive swimming exercise programme daily for a period of five days. The thiobarbituric acid reactive substances (TBARS, conjugated dienes, superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase were measured in the gastrocnemius muscle of the exercised animals. Results: The elevated levels of TBARS and conjugated dienes indicated the oxidative stress in the gastrocemius muscle of the exercised animals. The depleted activity levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the exercise animals indicated the increased oxidative stress and decreased antioxidative defense system in the muscle. Conclusions: The study suggests that prolonged strenuous exercise programme can induce oxidative stress and therefore an optimal level of exercise schedule should be advocated to obtain the maximum benefit of exercise programme.

  6. Activation of the hypothalamic-pituitary-adrenal stress axis induces cellular oxidative stress

    OpenAIRE

    Spiers, Jereme G.; Hsiao-Jou Cortina eChen; Conrad eSernia; Lavidis, Nickolas A.

    2015-01-01

    Glucocorticoids released from the adrenal gland in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis induce activity in the cellular reduction-oxidation (redox) system. The redox system is a ubiquitous chemical mechanism allowing the transfer of electrons between donor/acceptors and target molecules during oxidative phosphorylation while simultaneously maintaining the overall cellular environment in a reduced state. The objective of this review is to prese...

  7. Stress potentiates decision biases: A stress induced deliberation-to-intuition (SIDI model

    Directory of Open Access Journals (Sweden)

    Rongjun Yu

    2016-06-01

    Full Text Available Humans often make decisions in stressful situations, for example when the stakes are high and the potential consequences severe, or when the clock is ticking and the task demand is overwhelming. In response, a whole train of biological responses to stress has evolved to allow organisms to make a fight-or-flight response. When under stress, fast and effortless heuristics may dominate over slow and demanding deliberation in making decisions under uncertainty. Here, I review evidence from behavioral studies and neuroimaging research on decision making under stress and propose that stress elicits a switch from an analytic reasoning system to intuitive processes, and predict that this switch is associated with diminished activity in the prefrontal executive control regions and exaggerated activity in subcortical reactive emotion brain areas. Previous studies have shown that when stressed, individuals tend to make more habitual responses than goal-directed choices, be less likely to adjust their initial judgment, and rely more on gut feelings in social situations. It is possible that stress influences the arbitration between the emotion responses in subcortical regions and deliberative processes in the prefrontal cortex, so that final decisions are based on unexamined innate responses. Future research may further test this ‘stress induced deliberation-to-intuition’ (SIDI model and examine its underlying neural mechanisms.

  8. 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.

  9. Numerical simulation of an elementary Vortex-Induced-Vibration problem by using fully-coupled fluid solid system computation

    Directory of Open Access Journals (Sweden)

    M Pomarède

    2016-09-01

    Full Text Available Numerical simulation of Vortex-Induced-Vibrations (VIV of a rigid circular elastically-mounted cylinder submitted to a fluid cross-flow has been extensively studied over the past decades, both experimentally and numerically, because of its theoretical and practical interest for understanding Flow-Induced-Vibrations (FIV problems. In this context, the present article aims to expose a numerical study based on fully-coupled fluid-solid computations compared to previously published work [34], [36]. The computational procedure relies on a partitioned method ensuring the coupling between fluid and structure solvers. The fluid solver involves a moving mesh formulation for simulation of the fluid structure interface motion. Energy exchanges between fluid and solid models are ensured through convenient numerical schemes. The present study is devoted to a low Reynolds number configuration. Cylinder motion magnitude, hydrodynamic forces, oscillation frequency and fluid vortex shedding modes are investigated and the “lock-in” phenomenon is reproduced numerically. These numerical results are proposed for code validation purposes before investigating larger industrial applications such as configurations involving tube arrays under cross-flows [4].

  10. Stress-induced birefringence control in femtosecond laser glass welding

    Science.gov (United States)

    Gstalter, M.; Chabrol, G.; Bahouka, A.; Serreau, L.; Heitz, J.-L.; Taupier, G.; Dorkenoo, K.-D.; Rehspringer, J.-L.; Lecler, S.

    2017-11-01

    Glass welding by femtosecond laser pulses causes microscopic structural modifications, affecting the refractive index due to residual stress. Locally induced birefringence is studied by photoelasticimetry using a polarized light microscope. The study is performed on borosilicate thin glass plates using an industrial femtosecond laser generating 300 fs pulses at 500 kHz, with a 100 mm focusing length F-theta lens allowing fast welding. For low-energy deposition, the principal birefringence axes are determined to be homogenous along the seam and perpendicular and parallel to the laser scanning direction. Tensile stress is induced in the laser scanning direction by the welding seams. The induced birefringence is determined to be equivalent for in-volume irradiated track and welding seams. An inhomogeneity of the birefringence within the seam is observed for the first time at high-energy deposition. The distribution of the birefringence can be controlled with the laser scanning patterns. The amount of residual stress is measured by compensating the local birefringence. The birefringence Δ n is estimated at 2.4 × 10^{-4}, corresponding to a residual stress amount around 59 MPa. The influence of the welding geometry is also illustrated.

  11. Exercise-Induced Oxidative Stress Responses in the Pediatric Population

    Directory of Open Access Journals (Sweden)

    Alexandra Avloniti

    2017-01-01

    Full Text Available Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less information exists regarding oxidative stress responses and the underlying mechanisms in the pediatric population. Evidence suggests that exercise-induced redox perturbations may be valuable in order to monitor exercise-induced inflammatory responses and as such training overload in children and adolescents as well as monitor optimal growth and development. The purpose of this review was to provide an update on oxidative stress responses to acute and chronic exercise in youth. It has been documented that acute exercise induces age-specific transient alterations in both oxidant and antioxidant markers in children and adolescents. However, these responses seem to be affected by factors such as training phase, training load, fitness level, mode of exercise etc. In relation to chronic adaptation, the role of training on oxidative stress adaptation has not been adequately investigated. The two studies performed so far indicate that children and adolescents exhibit positive adaptations of their antioxidant system, as adults do. More studies are needed in order to shed light on oxidative stress and antioxidant responses, following acute exercise and training adaptations in youth. Available evidence suggests that small amounts of oxidative stress may be necessary for growth whereas the transition to adolescence from childhood may promote maturation of pro- and anti-oxidant mechanisms. Available evidence also suggests that obesity may negatively affect basal and exercise-related antioxidant responses in the peripubertal period during pre- and early-puberty.

  12. Microcantilever actuation generated by redox-induced surface stress

    Science.gov (United States)

    Tabard-Cossa, Vincent

    Electrochemically-induced changes in surface stress at the solid-liquid interface are measured using a differential cantilever-based sensor. The simultaneous, in situ measurements of the current (charge) and interfacial stress changes are performed by employing an AFM cantilever as both the working electrode (in a conventional three-probe electrochemical cell configuration) and as the mechanical transducer (bending of the cantilever). The custom-built instrument achieves a surface stress sensitivity of 1x10-4 N/m and a dynamic range of 5x105. Combining electrochemistry with cantilever-based sensing provides the extra surface characterization capability essential for the interpretation of the origin of the surface stress. The objective of the present study is to gain a better understanding of the mechanisms responsible for the nanomechanical motion of cantilever sensors during adsorption and absorption processes. The study of these simple model systems will lead to a general understanding of the cantilever-based sensor's response and provide insights into the physical origin of the measured surface stress. The surface stress generated by the electrochemically-controlled absorption of ions into a thin polypyrrole film is investigated. A compressive change in surface stress of about -2 N/m is measured when the polymer is electrochemically switched between its oxidized and neutral (swollen) state. The volume change of the polymer phase with respect to the gold-coated cantilever is shown to be responsible for the mechanical motion observed. The potential-induced surface stress and surface energy change on an Au(111)-textured cantilever, in a 0.1 M HClO4 electrolyte, are simultaneously measured. These measurements revealed that for solid electrodes these two thermodynamic parameters are significantly different. In the double layer region, a surface stress change of -0.55 +/-0.06 N/m is measured during ClO4- adsorption whereas the surface energy variation is smaller by

  13. Vibrations induced by HST passage on ballast and non-ballast tracks

    OpenAIRE

    Galvín, Pedro; Romero Ordóñez, Antonio; Domínguez Abascal, José

    2010-01-01

    Soil Dynamics and Earthquake Engineering, Sept. 2010 - Special Issue in honour of Prof. Anestis Veletsos. Postprint The use of ballastless slab track is significantly increasing in HST line technology. This development is due to some structural and operational advantages over ballasted track. In addition, floating slab tracks can be used to control ground-borne vibrations generated by surface and underground rail transportation systems. In this paper, a general and fully three dimension...

  14. Whole-body-vibration-induced increase in leg muscle activity during different squat exercises.

    Science.gov (United States)

    Roelants, Machteld; Verschueren, Sabine M P; Delecluse, Christophe; Levin, Oron; Stijnen, Valère

    2006-02-01

    This study analyzed leg muscle activity during whole-body vibration (WBV) training. Subjects performed standard unloaded isometric exercises on a vibrating platform (Power Plate): high squat (HS), low squat (LS), and 1-legged squat (OL). Muscle activity of the rectus femoris, vastus lateralis, vastus medialis, and gastrocnemius was recorded in 15 men (age 21.2 +/- 0.8 years) through use of surface electromyography (EMG). The exercises were performed in 2 conditions: with WBV and without (control [CO]) a vibratory stimulus of 35 Hz. Muscle activation during WBV was compared with CO and with muscle activation during isolated maximal voluntary contractions (MVCs). Whole-body vibration resulted in a significantly higher (p < 0.05) EMG root-mean-square compared with CO in all muscle groups and all exercises (between +39.9 +/- 17.5% and +360.6 +/- 57.5%). The increase in muscle activity caused by WBV was significantly higher (p < 0.05) in OL compared with HS and LS. In conclusion, WBV resulted in an increased activation of the leg muscles. During WBV, leg muscle activity varied between 12.6 and 82.4% of MVC values.

  15. Vocal nodules and edema may be due to vibration-induced rises in capillary pressure.

    Science.gov (United States)

    Czerwonka, Lukasz; Jiang, Jack J; Tao, Chao

    2008-04-01

    Vocal fold vibration may physically raise intravascular pressure to levels high enough to damage capillaries and result in leakage of erythrocytes. This type of injury is commonly seen in benign vocal fold lesions and is not well explained. Theoretical, retrospective. The relationship of intravascular pressure to vibration frequency and amplitude is derived and confirmed with a physical blood vessel model, then applied to published human measurements to estimate human intravascular pressures. Vocal fold intravascular pressure is predicted to have a quadratic dependence on both frequency and amplitude. During speaking, the pressure may rise to over 20 cmH2O, and may reach levels far higher for screaming and singing. Such pressure magnitudes are known to trigger inflammatory cascades and can lead to fluid leakage. They also have the potential for pharmacologic control with beta-agonists. Intravascular pressure likely rises significantly during vocal fold vibration and may lead to the type of injury seen in benign vocal fold lesions. The results support voice therapy aimed at reducing vibratory amplitude. More vibratory amplitude measurements need to be performed in a wider range of subjects before the full range of human vocal fold vascular pressures can be estimated.

  16. Low-frequency vibration treatment of bone marrow stromal cells induces bone repair in vivo

    Directory of Open Access Journals (Sweden)

    Shengwei He

    2017-01-01

    Full Text Available Objective(s:To study the effect of low-frequency vibration on bone marrow stromal cell differentiation and potential bone repair in vivo. Materials and Methods:Forty New Zealand rabbits were randomly divided into five groups with eight rabbits in each group. For each group, bone defects were generated in the left humerus of four rabbits, and in the right humerus of the other four rabbits. To test differentiation, bones were isolated and demineralized, supplemented with bone marrow stromal cells, and implanted into humerus bone defects. Varying frequencies of vibration (0, 12.5, 25, 50, and 100 Hz were applied to each group for 30 min each day for four weeks. When the bone defects integrated, they were then removed for histological examination. mRNA transcript levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor k-B ligan, and pre-collagen type 1 a were measured. Results:Humeri implanted with bone marrow stromal cells displayed elevated callus levels and wider, more prevalent, and denser trabeculae following treatment at 25 and 50 Hz. The mRNA levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor k-B ligand, and pre-collagen type 1 a were also markedly higher following 25 and 50 Hz treatment. Conclusion:Low frequency (25–50 Hz vibration in vivo can promote bone marrow stromal cell differentiation and repair bone injury.

  17. Turbulence-induced resonance vibrations cause pollen release in wind-pollinated Plantago lanceolata L. (Plantaginaceae)

    Science.gov (United States)

    Timerman, David; Greene, David F.; Urzay, Javier; Ackerman, Josef D.

    2014-01-01

    In wind pollination, the release of pollen from anthers into airflows determines the quantity and timing of pollen available for pollination. Despite the ecological and evolutionary importance of pollen release, wind–stamen interactions are poorly understood, as are the specific forces that deliver pollen grains into airflows. We present empirical evidence that atmospheric turbulence acts directly on stamens in the cosmopolitan, wind-pollinated weed, Plantago lanceolata, causing resonant vibrations that release episodic bursts of pollen grains. In laboratory experiments, we show that stamens have mechanical properties corresponding to theoretically predicted ranges for turbulence-driven resonant vibrations. The mechanical excitation of stamens at their characteristic resonance frequency caused them to resonate, shedding pollen vigorously. The characteristic natural frequency of the stamens increased over time with each shedding episode due to the reduction in anther mass, which increased the mechanical energy required to trigger subsequent episodes. Field observations of a natural population under turbulent wind conditions were consistent with these laboratory results and demonstrated that pollen is released from resonating stamens excited by small eddies whose turnover periods are similar to the characteristic resonance frequency measured in the laboratory. Turbulence-driven vibration of stamens at resonance may be a primary mechanism for pollen shedding in wind-pollinated angiosperms. The capacity to release pollen in wind can be viewed as a primary factor distinguishing animal- from wind-pollinated plants, and selection on traits such as the damping ratio and flexural rigidity may be of consequence in evolutionary transitions between pollination systems. PMID:25297315

  18. Vibration-induced muscle fatigue, a possible contribution to musculoskeletal injury.

    Science.gov (United States)

    Adamo, Diane E; Martin, Bernard J; Johnson, Peter W

    2002-11-01

    Localized muscle fatigue resulting from 30-min sustained and intermittent grip exertions of 5% maximal voluntary contraction (MVC) with and without hand-vibration exposure (10 Hz, 7 mm displacement amplitude) was investigated. Muscle fatigue was quantified by the magnitude of the twitch force elicited in the right flexor digitorum superficialis muscle of the long finger using the low-frequency fatigue (LFF) method. The influence of vibration in the sustained grip exertion condition exacerbates fatigue as seen with the reduction in twitch force 30-60 min post-work task. Intermittent low grip force exertion conditions with and without vibration exposure show negligible fatigue, suggesting the benefit of rest in the work cycle. Perception of muscle fatigue was dissociated from the objective measure of twitch force, suggesting that LFF was not perceived. The presence of LFF and the lack of perception of LFF may increase the risk for the development of musculoskeletal disorders. The findings of this study may apply to the design of the work cycles and tasks that require the use of vibratory tools.

  19. Oxidative stress in MeHg-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Marcelo, E-mail: farina@ccb.ufsc.br [Departamento de Bioquimica, Centro de Ciencias Biologicas, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States); Rocha, Joao B.T., E-mail: jbtrocha@yahoo.com.br [Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS (Brazil)

    2011-11-15

    Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically

  20. Oxidative stress induces senescence in human mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Brandl, Anita [Department of Anesthesiology, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg (Germany); Meyer, Matthias; Bechmann, Volker [Department of Trauma Surgery, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg (Germany); Nerlich, Michael [Department of Anesthesiology, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg (Germany); Angele, Peter, E-mail: Peter.Angele@klinik.uni-regensburg.de [Department of Trauma Surgery, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg (Germany)

    2011-07-01

    Mesenchymal stem cells (MSCs) contribute to tissue repair in vivo and form an attractive cell source for tissue engineering. Their regenerative potential is impaired by cellular senescence. The effects of oxidative stress on MSCs are still unknown. Our studies were to investigate into the proliferation potential, cytological features and the telomere linked stress response system of MSCs, subject to acute or prolonged oxidant challenge with hydrogen peroxide. Telomere length was measured using the telomere restriction fragment assay, gene expression was determined by rtPCR. Sub-lethal doses of oxidative stress reduced proliferation rates and induced senescent-morphological features and senescence-associated {beta}-galactosidase positivity. Prolonged low dose treatment with hydrogen peroxide had no effects on cell proliferation or morphology. Sub-lethal and prolonged low doses of oxidative stress considerably accelerated telomere attrition. Following acute oxidant insult p21 was up-regulated prior to returning to initial levels. TRF1 was significantly reduced, TRF2 showed a slight up-regulation. SIRT1 and XRCC5 were up-regulated after oxidant insult and expression levels increased in aging cells. Compared to fibroblasts and chondrocytes, MSCs showed an increased tolerance to oxidative stress regarding proliferation, telomere biology and gene expression with an impaired stress tolerance in aged cells.

  1. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadimehr, M., E-mail: mmohammadimehr@kashanu.ac.ir [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Mohammadi-Dehabadi, A.A. [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Department of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Maraghi, Z. Khoddami [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of)

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  2. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Science.gov (United States)

    Mohammadimehr, M.; Mohammadi-Dehabadi, A. A.; Maraghi, Z. Khoddami

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  3. Blood lactate levels as a biomarker for angling-induced stress in ...

    African Journals Online (AJOL)

    induced stress in African gamefish. Blood lactate levels were used as a biomarker for angling-induced metabolic stress in tigerfish caught by angling in the Okavango Delta, Botswana. Blood was drawn and analysed for blood lactate from 66 ...

  4. Biologically Synthesized Gold Nanoparticles Ameliorate Cold and Heat Stress-Induced Oxidative Stress in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Xi-Feng Zhang

    2016-06-01

    Full Text Available Due to their unique physical, chemical, and optical properties, gold nanoparticles (AuNPs have recently attracted much interest in the field of nanomedicine, especially in the areas of cancer diagnosis and photothermal therapy. Because of the enormous potential of these nanoparticles, various physical, chemical, and biological methods have been adopted for their synthesis. Synthetic antioxidants are dangerous to human health. Thus, the search for effective, nontoxic natural compounds with effective antioxidative properties is essential. Although AuNPs have been studied for use in various biological applications, exploration of AuNPs as antioxidants capable of inhibiting oxidative stress induced by heat and cold stress is still warranted. Therefore, one goal of our study was to produce biocompatible AuNPs using biological methods that are simple, nontoxic, biocompatible, and environmentally friendly. Next, we aimed to assess the antioxidative effect of AuNPs against oxidative stress induced by cold and heat in Escherichia coli, which is a suitable model for stress responses involving AuNPs. The response of aerobically grown E. coli cells to cold and heat stress was found to be similar to the oxidative stress response. Upon exposure to cold and heat stress, the viability and metabolic activity of E. coli was significantly reduced compared to the control. In addition, levels of reactive oxygen species (ROS and malondialdehyde (MDA and leakage of proteins and sugars were significantly elevated, and the levels of lactate dehydrogenase activity (LDH and adenosine triphosphate (ATP significantly lowered compared to in the control. Concomitantly, AuNPs ameliorated cold and heat-induced oxidative stress responses by increasing the expression of antioxidants, including glutathione (GSH, glutathione S-transferase (GST, super oxide dismutase (SOD, and catalase (CAT. These consistent physiology and biochemical data suggest that AuNPs can ameliorate cold and

  5. Antioxidant therapy for management of oxidative stress induced hypertension.

    Science.gov (United States)

    Ahmad, Khalil Ali; Yuan Yuan, Dai; Nawaz, Waqas; Ze, Hong; Zhuo, Chen Xue; Talal, Bashar; Taleb, Abdoh; Mais, Enos; Qilong, Ding

    2017-04-01

    Hypertension is considered as the most common risk factor for cardiovascular diseases, also is regarded as a leading cause of the mortality and morbidity worldwide. The mechanisms underlying the pathological process of hypertension are not completely explained. However, there is growing evidence that increased oxidative stress plays an important role in the pathophysiology of hypertension. Several preclinical studies and clinical trials have indicated that antioxidant therapy is important for management of hypertension, using antioxidants compounds such as alpha tocopherol (Vit E) and ascorbic acid (Vit C), polyphenols with others and some antihypertensive drugs that are now in clinical use (e.g. ACEIs, ARBs, novel B-blockers, dihydropyridine CCBs) which have antioxidative pleiotropic effects. The purpose of this review is to highlight the importance of antioxidant therapy for management of oxidative stress induced hypertension. Furthermore, we review the current knowledge in the oxidative stress and its significance in hypertension.

  6. Chest Pain and Mental Stress Induced Myocardial Ischemia: Sex Differences.

    Science.gov (United States)

    Pimple, Pratik; Hammadah, Muhammad; Wilmot, Kobina; Ramadan, Ronnie; Mheid, Ibhar Al; Levantsevych, Oleksiy; Sullivan, Samaah; Garcia, Ernest V; Nye, Jonathon; Shah, Amit J; Ward, Laura; Mehta, Puja; Raggi, Paolo; Bremner, J Douglas; Quyyumi, Arshed A; Vaccarino, Viola

    2017-12-07

    Mental stress-induced myocardial ischemia (MSIMI) is a frequent phenomenon in patients with coronary artery disease. Women with coronary artery disease tend to have more MSIMI and more chest pain/anginal symptoms than men, but whether the association between MSIMI and angina burden differs in women and men, is unknown. This was a cross-sectional study with experimental manipulation of 950 individuals with stable coronary artery disease. Chest pain/angina frequency in the previous 4 weeks was assessed with the Seattle Angina Questionnaire's angina-frequency subscale. MSIMI was assessed with myocardial perfusion imaging during mental stress (standardized public speaking task). Presence of MSIMI was based on expert readers and established criteria. A conventional (exercise or pharmacological) stress test was used as a control condition. Overall, 338 individuals (37%) reported angina; 112 (12%) developed MSIMI, and 256 (29%) developed conventional stress ischemia. Women who reported angina had almost double the probability to develop MSIMI (19% vs. 10%), adjusted prevalence rate ratio (PRR)= 1.90, 95% CI: 1.04-3.46), while there was no such difference in men (11% vs. 11%, adjusted PRR= 1.09, 95% CI: 0.66-1.82). No association was found between angina symptoms and conventional stress ischemia for either women or men. Results for ischemia as a continuous variable were similar. In women, but not in men, anginal symptoms may be a marker of vulnerability towards ischemia induced by psychological stress. These results highlight the psychosocial origins of angina in women, and may have important implications for the management and prognosis of women with angina. Copyright © 2017. Published by Elsevier Inc.

  7. A review: oxidative stress in fish induced by pesticides.

    Science.gov (United States)

    Slaninova, Andrea; Smutna, Miriam; Modra, Helena; Svobodova, Zdenka

    2009-01-01

    The knowledge in oxidative stress in fish has a great importance for environmental and aquatic toxicology. Because oxidative stress is evoked by many chemicals including some pesticides, pro-oxidant factors' action in fish organism can be used to assess specific area pollution or world sea pollution. Hepatotoxic effect of DDT may be related with lipid peroxidation. Releasing of reactive oxygen species (ROS) after HCB exposure can be realized via two ways: via the uncoupling of the electron transport chain from monooxygenase activity and via metabolism of HCB major metabolite pentachlorophenol. Chlorothalonil disrupts mitochondrial metabolism due to the impairment of NADPH oxidase function. Activation of spleen macrophages and a decrease of catalase (CAT) activity have been observed after endosulfan exposure. Excessive release of superoxide radicals after etoxazole exposure can cause a decrease of CAT activity and increase phagocytic activity of splenocytes. Anticholinergic activity of organophosphates leads to the accumulation of ROS and resulting lipid peroxidation. Carbaryl induces changes in the content of glutathione and antioxidant enzymes activities. The antioxidant enzymes changes have been observed after actuation of pesticides deltamethrin and cypermethrin. Bipyridyl herbicides are able to form redox cycles and thereby cause oxidative stress. Low concentrations of simazine do not cause oxidative stress in carps during sub-chronic tests while sublethal concentrations of atrazin can induce oxidative stress in bluegill sunfish. Butachlor causes increased activity of superoxide dismutase -catalase system in the kidney. Rotenon can inhibit the electron transport in mitochondria and thereby increase ROS production. Dichloroaniline, the metabolite of diuron, has oxidative effects. Oxidative damage from fenpyroximate actuation is related to the disruption of mitochondrial redox respiratory chain. Low concentration of glyphosate can cause mild oxidative stress.

  8. Silymarin Suppresses Cellular Inflammation By Inducing Reparative Stress Signaling

    Energy Technology Data Exchange (ETDEWEB)

    Lovelace, Erica S.; Wagoner, Jessica; MacDonald, James; Bammler, Theo; Bruckner, Jacob; Brownell, Jessica; Beyer, Richard; Zink, Erika M.; Kim, Young-Mo; Kyle, Jennifer E.; Webb-Robertson, Bobbie-Jo M.; Waters, Katrina M.; Metz, Thomas O.; Farin, Federico; Oberlies, Nicholas H.; Polyak, Steve

    2015-08-28

    Silymarin (SM), a natural product, is touted as a liver protectant and preventer of both chronic inflammation and diseases. To define how SM elicits these effects at a systems level, we performed transcriptional profiling, metabolomics, and signaling studies in human liver and T cell lines. Multiple pathways associated with cellular stress and metabolism were modulated by SM treatment within 0.5 to four hours: activation of Activating Transcription Factor 4 (ATF-4) and adenosine monophosphate protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) signaling, the latter being associated with induction of DNA-damage-inducible transcript 4 (DDIT4). Metabolomics analyses revealed suppression of glycolytic, TCA cycle, and amino acid metabolism by SM treatment. Antiinflammatory effects arose with prolonged (i.e. 24 hours) SM exposure, with suppression of multiple proinflammatory mRNAs and nuclear factor kappa B (NF-κB) and forkhead box O (FOXO) signaling. Studies with murine knock out cells revealed that SM inhibition of both mTOR and NF-κB was partially AMPK dependent, while SM inhibition of the mTOR pathway in part required DDIT4. Thus, SM activates stress and repair responses that culminate in an anti-inflammatory phenotype. Other natural products induced similar stress responses, which correlated with their ability to suppress inflammation. Therefore, natural products like SM may be useful as tools to define how metabolic, stress, and repair pathways regulate cellular inflammation.

  9. Silymarin Suppresses Cellular Inflammation By Inducing Reparative Stress Signaling

    Science.gov (United States)

    Lovelace, Erica S.; Wagoner, Jessica; MacDonald, James; Bammler, Theo; Bruckner, Jacob; Brownell, Jessica; Beyer, Richard; Zink, Erika M.; Kim, Young-Mo; Kyle, Jennifer E.; Webb-Robertson, Bobbie-Jo; Waters, Katrina M.; Metz, Thomas O.; Farin, Federico; Oberlies, Nicholas H.; Polyak, Stephen J.

    2016-01-01

    Silymarin, a characterized extract of the seeds of milk thistle (Silybum marianum), suppresses cellular inflammation. To define how this occurs, transcriptional profiling, metabolomics, and signaling studies were performed in human liver and T cell lines. Cellular stress and metabolic pathways were modulated within 4 h of silymarin treatment: activation of Activating Transcription Factor 4 (ATF-4) and adenosine monophosphate protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) signaling, the latter being associated with induction of DNA-damage-inducible transcript 4 (DDIT4). Metabolomics analyses revealed silymarin suppression of glycolytic, tricarboxylic acid (TCA) cycle, and amino acid metabolism. Anti-inflammatory effects arose with prolonged (i.e. 24 h) silymarin exposure, with suppression of multiple pro-inflammatory mRNAs and signaling pathways including nuclear factor kappa B (NF-κB) and forkhead box O (FOXO). Studies with murine knock out cells revealed that silymarin inhibition of both mTOR and NF-κB was partially AMPK dependent, while silymarin inhibition of mTOR required DDIT4. Other natural products induced similar stress responses, which correlated with their ability to suppress inflammation. Thus, natural products activate stress and repair responses that culminate in an anti-inflammatory cellular phenotype. Natural products like silymarin may be useful as tools to define how metabolic, stress, and repair pathways regulate cellular inflammation. PMID:26186142

  10. Stress-induced cardiomyopathy (Takotsubo – broken heart and mind?

    Directory of Open Access Journals (Sweden)

    Redfors B

    2013-04-01

    Full Text Available Björn Redfors, Yangzhen Shao, Elmir Omerovic Department of Molecular and Clinical Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden Abstract: Stress-induced cardiomyopathy (SIC, also known as Takotsubo cardiomyopathy, is characterized by severe but potentially reversible regional left ventricular wall motion abnormalities, ie, akinesia, in the absence of explanatory angiographic evidence of a coronary occlusion. The typical pattern is that of an akinetic apex with preserved contractions in the base, but other variants are also common, including basal or midmyocardial akinesia with preserved apical function. The pathophysiology of SIC remains largely unknown but catecholamines are believed to play a pivotal role. The diverse array of triggering events that have been linked to SIC are arbitrarily categorized as either emotional or somatic stressors. These categories can be considered as different elements of a continuous spectrum, linked through the interface of neurology and psychiatry. This paper reviews our current knowledge of SIC, with focus on the intimate relationship between the brain and the heart. Keywords: stress-induced cardiomyopathy, takotsubo cardiomyopathy, catecholamine, cerebral injury, emotional stress, somatic stress

  11. Turbulence-induced resonance vibrations cause pollen release in wind-pollinated Plantago lanceolata L. (Plantaginaceae).

    Science.gov (United States)

    Timerman, David; Greene, David F; Urzay, Javier; Ackerman, Josef D

    2014-12-06

    In wind pollination, the release of pollen from anthers into airflows determines the quantity and timing of pollen available for pollination. Despite the ecological and evolutionary importance of pollen release, wind-stamen interactions are poorly understood, as are the specific forces that deliver pollen grains into airflows. We present empirical evidence that atmospheric turbulence acts directly on stamens in the cosmopolitan, wind-pollinated weed, Plantago lanceolata, causing resonant vibrations that release episodic bursts of pollen grains. In laboratory experiments, we show that stamens have mechanical properties corresponding to theoretically predicted ranges for turbulence-driven resonant vibrations. The mechanical excitation of stamens at their characteristic resonance frequency caused them to resonate, shedding pollen vigorously. The characteristic natural frequency of the stamens increased over time with each shedding episode due to the reduction in anther mass, which increased the mechanical energy required to trigger subsequent episodes. Field observations of a natural population under turbulent wind conditions were consistent with these laboratory results and demonstrated that pollen is released from resonating stamens excited by small eddies whose turnover periods are similar to the characteristic resonance frequency measured in the laboratory. Turbulence-driven vibration of stamens at resonance may be a primary mechanism for pollen shedding in wind-pollinated angiosperms. The capacity to release pollen in wind can be viewed as a primary factor distinguishing animal- from wind-pollinated plants, and selection on traits such as the damping ratio and flexural rigidity may be of consequence in evolutionary transitions between pollination systems. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  12. Vortex dynamics and flow-induced vibrations arising from a vortex ring passing tangentially over a flexible plate

    Science.gov (United States)

    Pirnia, Alireza; Hu, JiaCheng; Peterson, Sean D.; Erath, Byron D.

    2017-10-01

    The extraction of energy from vortical structures advecting through an ambient environment is a topic of interest due to the potential to power miniature in situ sensors and monitors. This work investigates the vortex dynamics and flow-induced vibrations of a flexible plate arising from a vortex ring passing tangentially over it. Experimental measurements of the flow field and plate dynamics are performed in tandem with a coupled potential flow/Kirchhoff-Love plate model in order to (i) elucidate the physics of the vortex-plate interactions in the specified orientation and relate the energy exchange between the ring and the plate to the attendant vortex dynamics; (ii) validate the potential flow model and provide any needed corrections to account for the simplifying assumptions; and (iii) provide empirical data for estimating energy harvesting capabilities in the specified orientation. The plate loading arises as a result of an initial down-wash, followed quickly by a region of reduced pressure as the vortex core passes over the plate. The fundamental physics of the interaction is discussed, identifying three regimes. When the centerline of the vortex ring is positioned greater than approximately 2 vortex ring radii away from the plate it can be considered to be in the far-field, and the resulting vibrations are well predicted through potential flow, once the plate dynamics are corrected for edge effects arising from a finite plate width. As the offset distance of the vortex ring is decreased, diffusion of induced vorticity on the plate into the flow field significantly alters the fluid dynamics, pressure loading, and the resultant plate dynamics, and dramatically increases the strain energy in comparison with the potential flow model predictions. A first-order correction to the potential flow model is proposed to account for the finite plate width, while empirical correlations are presented for the plate strain energy in cases where ring/induced vorticity

  13. The prevalence of posttraumatic stress among women requesting induced abortion.

    Science.gov (United States)

    Wallin Lundell, Inger; Sundström Poromaa, Inger; Frans, Orjan; Helström, Lotti; Högberg, Ulf; Moby, Lena; Nyberg, Sigrid; Sydsjö, Gunilla; Georgsson Öhman, Susanne; Östlund, Ingrid; Skoog Svanberg, Agneta

    2013-12-01

    To describe the prevalence and pattern of traumatic experiences, to assess the prevalence of posttraumatic stress disorder (PTSD) and posttraumatic stress symptoms (PTSS), to identify risk factors for PTSD and PTSS, and to analyse the association of PTSD and PTSS with concomitant anxiety and depressive symptoms in women requesting induced abortion. A Swedish multi-centre study of women requesting an induced abortion. The Screen Questionnaire - Posttraumatic Stress Disorder was used for research diagnoses of PTSD and PTSS. Anxiety and depressive symptoms were evaluated by the Hospital Anxiety and Depression Scale (HADS). Of the 1514 respondents, almost half reported traumatic experiences. Lifetime- and point prevalence of PTSD were 7% (95% confidence interval [CI]: 5.8-8.5) and 4% (95% CI: 3.1-5.2), respectively. The prevalence of PTSS was 23% (95% CI: 21.1-25.4). Women who reported symptoms of anxiety or depression when requesting abortion were more likely to have ongoing PTSD or PTSS. Also single-living women and smokers displayed higher rates of ongoing PTSD. Although PTSD is rare among women who request an induced abortion, a relatively high proportion suffers from PTSS. Abortion seeking women with trauma experiences and existing or preexisting mental disorders need more consideration and alertness when counselled for termination.

  14. Cryo Cooler Induced Micro-Vibration Disturbances to the Hubble Space Telescope

    Science.gov (United States)

    Jedrich, Nick; Zimbelman, Darrell; Turczyn, Mark; Sills, Joel; Voorhees, Carl; Clapp, Brian; Brumfield, Mark (Technical Monitor)

    2002-01-01

    This paper presents an overview of the Hubble Space Telescope (HST) Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Cryo Cooler (MCC) system, a description of the micro-vibration characterization testing performed, and a discussion of the simulated performance. The NCC is a reverse Brayton cycle system that employs micro turbo-machinery to provide cooling to the NICMOS instrument. Extensive testing was conducted to quantify the expected on-orbit disturbances caused by the micro turbo-machinery and provide input to a flexible-body dynamic simulation to demonstrate compliance with the HST 7 milli-arcsecond root mean square jitter requirement.

  15. Observation of sound-induced corneal vibrational modes by optical coherence tomography

    OpenAIRE

    Akca, B. Imran; Chang, Ernest W.; Kling, Sabine; Ramier, Antoine; Scarcelli, Giuliano; Marcos, Susana; Yun, Seok H.

    2015-01-01

    The mechanical stability of the cornea is critical for maintaining its normal shape and refractive function. Here, we report an observation of the mechanical resonance modes of the cornea excited by sound waves and detected by using phase-sensitive optical coherence tomography. The cornea in bovine eye globes exhibited three resonance modes in a frequency range of 50-400 Hz. The vibration amplitude of the fundamental mode at 80-120 Hz was ~8 µm at a sound pressure level of 100 dB (2 Pa). Vibr...

  16. Modeling Diffusion Induced Stresses for Lithium-Ion Battery Materials

    Science.gov (United States)

    Chiu Huang, Cheng-Kai

    Advancing lithium-ion battery technology is of paramount importance for satisfying the energy storage needs in the U.S., especially for the application in the electric vehicle industry. To provide a better acceleration for electric vehicles, a fast and repeatable discharging rate is required. However, particle fractures and capacity loss have been reported under high current rate (C-rate) during charging/discharging and after a period of cycling. During charging and discharging, lithium ions extract from and intercalate into electrode materials accompanied with the volume change and phase transition between Li-rich phase and Li-poor phase. It is suggested that the diffusion-induced-stress is one of the main reasons causing capacity loss due to the mechanical degradation of electrode particles. Therefore, there is a fundamental need to provide a mechanistic understanding by considering the structure-mechanics-property interactions in lithium-ion battery materials. Among many cathode materials, the olivine-based lithium-iron-phosphate (LiFePO4) with an orthorhombic crystal structure is one of the promising cathode materials for the application in electric vehicles. In this research we first use a multiphysic approach to investigate the stress evolution, especially on the phase boundary during lithiation in single LiFePO4 particles. A diffusion-controlled finite element model accompanied with the experimentally observed phase boundary propagation is developed via a finite element package, ANSYS, in which lithium ion concentration-dependent anisotropic material properties and volume misfits are incorporated. The stress components on the phase boundary are used to explain the Mode I, Mode II, and Mode III fracture propensities in LiFePO4 particles. The elastic strain energy evolution is also discussed to explain why a layer-by-layer lithium insertion mechanism (i.e. first-order phase transformation) is energetically preferred. Another importation issue is how current

  17. Study of wind-induced vibrations in tall buildings with tuned mass dampers taking into account vortices effects

    Science.gov (United States)

    Momtaz, Ali Ajilian; Abdollahian, Mohamadreza Akhavan; Farshidianfar, Anooshiravan

    2017-11-01

    In recent years, construction of tall buildings has been of great interest. Use of lightweight materials in such structures reduces stiffness and damping, making the building more influenced by wind loads. Moreover, tall buildings of more than 30 to 40 stories, depending on the geographical location, the wind effects are more influential than earthquakes. In addition, the complexity of the effects of wind flow on the structure due to the interaction of the fluid flow and solid body results in serious damages to the structure by eliminating them. Considering the importance of the issue, the present study investigates the phenomenon of wind-induced vibration on high-rise buildings, taking into account the effects of vortices created by the fluid flow and the control of this phenomenon. To this end, the governing equations of the structure, the fluid flow and the tuned mass damper (TMD) are first introduced, and their coefficient values are extracted according to the characteristics of ACT skyscraper in Japan. Then, these three coupled equations are solved using a program coded in MATLAB. After validation of the results, the effects of wind loads are analyzed and considered with regard to the effects of vortices and the use of TMD, and are compared with the results of the state where no vortices are considered. Generally, the results of this study point out the significance of vibrations caused by vortices in construction of engineering structures as well as the appropriate performance of a TMD in reducing oscillations in tall buildings.

  18. Fractalkine Attenuates Microglial Cell Activation Induced by Prenatal Stress

    Directory of Open Access Journals (Sweden)

    Joanna Ślusarczyk

    2016-01-01

    Full Text Available The potential contribution of inflammation to the development of neuropsychiatric diseases has recently received substantial attention. In the brain, the main immune cells are the microglia. As they are the main source of inflammatory factors, it is plausible that the regulation of their activation may be a potential therapeutic target. Fractalkine (CX3CL1 and its receptor CX3CR1 play a crucial role in the control of the biological activity of the microglia. In the present study, using microglial cultures we investigated whether fractalkine is able to reverse changes in microglia caused by a prenatal stress procedure. Our study found that the microglia do not express fractalkine. Prenatal stress decreases the expression of the fractalkine receptor, which in turn is enhanced by the administration of exogenous fractalkine. Moreover, treatment with fractalkine diminishes the prenatal stress-induced overproduction of proinflammatory factors such as IL-1β, IL-18, IL-6, TNF-α, CCL2, or NO in the microglial cells derived from prenatally stressed newborns. In conclusion, the present results revealed that the pathological activation of microglia in prenatally stressed newborns may be attenuated by fractalkine administration. Therefore, understanding of the role of the CX3CL1-CX3CR1 system may help to elucidate the mechanisms underlying the neuron-microglia interaction and its role in pathological conditions in the brain.

  19. Mid-Ventricular Variant of Dobutamine-Induced Stress Cardiomyopathy.

    Science.gov (United States)

    Chandraprakasam, Satish; Kanuri, Swapna; Hunter, Claire

    2015-05-01

    Dobutamine stress testing is a commonly used modality in detecting and estimating the prognosis in coronary artery disease (CAD). Although it is well tolerated by most patients, adverse events have been reported. Rarely, transient wall motion abnormalities can occur in the absence of obstructive CAD to suggest stress cardiomyopathy. We report a 48-year-old female with intermittent chest pain. Her physical exam, cardiac enzymes and transthoracic echocardiogram were unremarkable. She underwent dobutamine stress echocardiogram to rule out obstructive CAD. After 40 micrograms (mcg)/kg/minute and 0.5 mg atropine, she complained of intense chest pain and became hypertensive. Stress echocardiogram demonstrated mid-anterior and mid-septal hypokinesis. Emergent coronary angiogram demonstrated normal coronaries. Left ventricular angiogram in the right anterior oblique projection revealed mid-ventricular ballooning during systole with apical and basal hypercontractility. Patient demonstrated excellent recovery with expectant management. The mechanism of mid-variant of Dobutamine-induced stress cardiomyopathy remains unclear. We think that multiple mechanisms are involved and this risk should be considered in patients with comorbid psychiatric conditions and with use of centrally acting stimulants.

  20. Molecular mechanism of emotional stress-induced and catecholamine-induced heart attack.

    Science.gov (United States)

    Ueyama, Takashi; Senba, Emiko; Kasamatsu, Ken; Hano, Takuzo; Yamamoto, Katsuhiro; Nishio, Ichiro; Tsuruo, Yoshihiro; Yoshida, Ken-ichi

    2003-01-01

    Emotional or physical stress triggers 'tako-tsubo' cardiomyopathy or 'transient left ventricular apical ballooning', but the pathogenesis is unclear. In response to the immobilization stress of rats, a useful model of emotional stress, rapid activation of p44/p42 mitogen-activated protein kinase was observed in the heart, followed by a transient upregulation of immediate early genes in the smooth muscle cells of coronary arteries, the endothelial cells and the myocardium. Heat shock protein 70 was induced in the aortic and coronary arterial smooth muscle cells and in the myocardium. Natriuretic peptide genes were also upregulated in the myocardium. Sequential gene expression can be considered as an adaptive response to emotional stress. Blocking of both alpha-adrenoceptors and beta-adrenoceptors eliminated the upregulation of immediate early genes induced by stress, while alpha-agonists and beta-agonists upregulated immediate early genes in the perfused heart. Activation of alpha-adrenoceptors and beta-adrenoceptors is the primary trigger of emotional stress-induced molecular changes in the heart.

  1. Soyasaponin Bb Protects Rat Hepatocytes from Alcohol-Induced Oxidative Stress by Inducing Heme Oxygenase-1.

    Science.gov (United States)

    Lijie, Zhu; Ranran, Fu; Xiuying, Liu; Yutang, He; Bo, Wang; Tao, Ma

    2016-01-01

    It has been known that oxidative stress induced by alcohol played a crucial role in the formation of alcoholic liver disease. Although the formation mechanisms underlying liver injury induced by alcohol still remained largely unknown, it has been considered that oxidative stress played a core role in the pathogenesis of hepatocyte damage. The aim of this study was to investigate the effects of soyasaponin Bb (Ss-Bb) on oxidative stress in alcohol-induced rat hepatocyte injury. It has been shown that the administration of Ss-Bb could significantly restore antioxidant activity in BRL 3A cells. Moreover, the impaired liver function and morphology changes resulting from ethanol exposure were improved by Ss-Bb treatment. Treatment with a pharmacological inhibitor of haem oxygenase-1 (HO-1) indicated a critical role of HO-1 in mediating the protective role. Finally, we found that pretreatment with Ss-Bb to ethanol exposure cells increased the expression level of HO-1. It was suggested that Ss-Bb may protect against alcohol-induced hepatocyte injury through ameliorating oxidative stress, and the induction of HO-1 was an important protective mechanism. Effects of soyasaponin Bb was investigated on oxidative stress in rat hepatocytesCell viability and antioxidant capacities were evaluated to determine the effectsThe expression level of HO-1 was measured to reveal the proptective mechanisms.

  2. Tactile Perception of Roughness and Hardness to Discriminate Materials by Friction-Induced Vibration.

    Science.gov (United States)

    Ding, Shuyang; Pan, Yunlu; Tong, Mingsi; Zhao, Xuezeng

    2017-11-28

    The human fingertip is an exquisitely powerful bio-tactile sensor in perceiving different materials based on various highly-sensitive mechanoreceptors distributed all over the skin. The tactile perception of surface roughness and material hardness can be estimated by skin vibrations generated during a fingertip stroking of a surface instead of being maintained in a static position. Moreover, reciprocating sliding with increasing velocities and pressures are two common behaviors in humans to discriminate different materials, but the question remains as to what the correlation of the sliding velocity and normal load on the tactile perceptions of surface roughness and hardness is for material discrimination. In order to investigate this correlation, a finger-inspired crossed-I beam structure tactile tester has been designed to mimic the anthropic tactile discrimination behaviors. A novel method of characterizing the fast Fourier transform integral (FFT) slope of the vibration acceleration signal generated from fingertip rubbing on surfaces at increasing sliding velocity and normal load, respectively, are defined as k v and k w , and is proposed to discriminate the surface roughness and hardness of different materials. Over eight types of materials were tested, and they proved the capability and advantages of this high tactile-discriminating method. Our study may find applications in investigating humanoid robot perceptual abilities.

  3. Tactile Perception of Roughness and Hardness to Discriminate Materials by Friction-Induced Vibration

    Directory of Open Access Journals (Sweden)

    Shuyang Ding

    2017-11-01

    Full Text Available The human fingertip is an exquisitely powerful bio-tactile sensor in perceiving different materials based on various highly-sensitive mechanoreceptors distributed all over the skin. The tactile perception of surface roughness and material hardness can be estimated by skin vibrations generated during a fingertip stroking of a surface instead of being maintained in a static position. Moreover, reciprocating sliding with increasing velocities and pressures are two common behaviors in humans to discriminate different materials, but the question remains as to what the correlation of the sliding velocity and normal load on the tactile perceptions of surface roughness and hardness is for material discrimination. In order to investigate this correlation, a finger-inspired crossed-I beam structure tactile tester has been designed to mimic the anthropic tactile discrimination behaviors. A novel method of characterizing the fast Fourier transform integral (FFT slope of the vibration acceleration signal generated from fingertip rubbing on surfaces at increasing sliding velocity and normal load, respectively, are defined as kv and kw, and is proposed to discriminate the surface roughness and hardness of different materials. Over eight types of materials were tested, and they proved the capability and advantages of this high tactile-discriminating method. Our study may find applications in investigating humanoid robot perceptual abilities.

  4. Numerical investigation of the vortex-induced vibration of an elastically mounted circular cylinder at high Reynolds number (Re = 104 and low mass ratio using the RANS code.

    Directory of Open Access Journals (Sweden)

    Niaz Bahadur Khan

    Full Text Available This study numerically investigates the vortex-induced vibration (VIV of an elastically mounted rigid cylinder by using Reynolds-averaged Navier-Stokes (RANS equations with computational fluid dynamic (CFD tools. CFD analysis is performed for a fixed-cylinder case with Reynolds number (Re = 104 and for a cylinder that is free to oscillate in the transverse direction and possesses a low mass-damping ratio and Re = 104. Previously, similar studies have been performed with 3-dimensional and comparatively expensive turbulent models. In the current study, the capability and accuracy of the RANS model are validated, and the results of this model are compared with those of detached eddy simulation, direct numerical simulation, and large eddy simulation models. All three response branches and the maximum amplitude are well captured. The 2-dimensional case with the RANS shear-stress transport k-w model, which involves minimal computational cost, is reliable and appropriate for analyzing the characteristics of VIV.

  5. Adrenal-derived stress hormones modulate ozone-induced ...

    Science.gov (United States)

    Ozone-induced systemic effects are modulated through activation of the neuro-hormonal stress response pathway. Adrenal demedullation (DEMED)or bilateral total adrenalectomy (ADREX) inhibits systemic and pulmonary effect of acute ozone exposure. To understand the influence of adrenal-derived stress hormones in mediating ozone-induced lung injury/inflammation, we assessed global gene expression (mRNA sequencing) and selected proteins in lung tissues from male Wistar-Kyoto rats that underwent DEMED, ADREX, or sham surgery (SHAM)prior to their exposure to air or ozone (1 ppm),4 h/day for 1 or 2days. Ozone exposure significantly changed the expression of over 2300 genes in lungs of SHAM rats, and these changes were markedly reduced in DEMED and ADREX rats. SHAM surgery but not DEMED or ADREX resulted in activation of multiple ozone-responsive pathways, including glucocorticoid, acute phase response, NRF2, and Pl3K-AKT.Predicted targets from sequencing data showed a similarity between transcriptional changes induced by ozone and adrenergic and steroidal modulation of effects in SHAM but not ADREX rats. Ozone-induced Increases in lung 116 in SHAM rats coincided with neutrophilic Inflammation, but were diminished in DEMED and ADREX rats. Although ozone exposure in SHAM rats did not significantly alter mRNA expression of lfny and 11-4, the IL-4 protein and ratio of IL-4 to IFNy (IL-4/IFNy) proteins increased suggesting a tendency for a Th2 response. This did not occur

  6. Hexavalent chromium induced oxidative stress and apoptosis in Pycnoporus sanguineus.

    Science.gov (United States)

    Feng, Mi; Yin, Hua; Peng, Hui; Liu, Zehua; Lu, Guining; Dang, Zhi

    2017-09-01

    White rot fungi have been proved to be a promising option for the removal of heavy metals, understanding their toxic response to heavy metals is conducive to developing and popularizing fungi-based remediation technologies so as to lessen the hazard of heavy metals. In this study, Cr(VI)-induced oxidative stress and apoptosis in Pycnoporus sanguineus, a species of white rot fungi were investigated. The results suggested that high level of Cr(VI) promoted the formation of ROS, including H2O2, O2(•-) and ·OH. With the increment of Cr(VI) concentration, the SOD and CAT activity along with GSH content increased within the first 24 h, but decreased afterward, companied with a significant enhancement of MDA content. Cr(VI)-induced oxidative damage further caused and aggravated apoptosis in P. sanguineus, especially at Cr(VI) concentrations above 20 mg/L. Cr(VI)-induced apoptosis was involved with mitochondrial dysfunction including mitochondrial depolarization, the enhancement of mitochondrial permeability and release of cytochrome c. The early and late apoptosis hallmarks, such as metacaspase activation, phosphatidylserine (PS) externalization, DNA fragmentation and the nuclear condensation and fragmentation were observed. Moreover, we also found disturbances of ion homeostasis, which was featured by K(+) effluxes and overload of cytoplasmic and mitochondrial Ca(2+).Based on these results, we suggest that Cr(VI) induced oxidative stress and apoptosis in white rot fungi, P. sanguineus. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Aloin Protects Skin Fibroblasts from Heat Stress-Induced Oxidative Stress Damage by Regulating the Oxidative Defense System.

    Directory of Open Access Journals (Sweden)

    Fu-Wei Liu

    Full Text Available Oxidative stress is commonly involved in the pathogenesis of skin damage induced by environmental factors, such as heat stress. Skin fibroblasts are responsible for the connective tissue regeneration and the skin recovery from injury. Aloin, a bioactive compound in Aloe vera, has been reported to have various pharmacological activities, such as anti-inflammatory effects. The aim of this study was to investigate the protective effect of aloin against heat stress-mediated oxidative stress in human skin fibroblast Hs68 cells. Hs68 cells were first incubated at 43°C for 30 min to mimic heat stress. The study was further examined if aloin has any effect on heat stress-induced oxidative stress. We found that aloin protected Hs68 cells against heat stress-induced damage, as assessed by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay. Aloin protected Hs68 cells by regulating reactive oxygen species production and increasing the levels of glutathione, cytosolic and mitochondrial superoxide dismutase. Aloin also prevented the elevation of thiobarbituric acid reactive substances and the reduction of 8-OH-dG induced by heat stress. These results indicated that aloin protected human skin fibroblasts from heat stress-induced oxidative stress damage by regulating the oxidative defense system.

  8. Aloin Protects Skin Fibroblasts from Heat Stress-Induced Oxidative Stress Damage by Regulating the Oxidative Defense System.

    Science.gov (United States)

    Liu, Fu-Wei; Liu, Fu-Chao; Wang, Yu-Ren; Tsai, Hsin-I; Yu, Huang-Ping

    2015-01-01

    Oxidative stress is commonly involved in the pathogenesis of skin damage induced by environmental factors, such as heat stress. Skin fibroblasts are responsible for the connective tissue regeneration and the skin recovery from injury. Aloin, a bioactive compound in Aloe vera, has been reported to have various pharmacological activities, such as anti-inflammatory effects. The aim of this study was to investigate the protective effect of aloin against heat stress-mediated oxidative stress in human skin fibroblast Hs68 cells. Hs68 cells were first incubated at 43°C for 30 min to mimic heat stress. The study was further examined if aloin has any effect on heat stress-induced oxidative stress. We found that aloin protected Hs68 cells against heat stress-induced damage, as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay. Aloin protected Hs68 cells by regulating reactive oxygen species production and increasing the levels of glutathione, cytosolic and mitochondrial superoxide dismutase. Aloin also prevented the elevation of thiobarbituric acid reactive substances and the reduction of 8-OH-dG induced by heat stress. These results indicated that aloin protected human skin fibroblasts from heat stress-induced oxidative stress damage by regulating the oxidative defense system.

  9. Hyperglycemia-induced diaphragm weakness is mediated by oxidative stress

    Science.gov (United States)

    2014-01-01

    Introduction A major consequence of ICU-acquired weakness (ICUAW) is diaphragm weakness, which prolongs the duration of mechanical ventilation. Hyperglycemia (HG) is a risk factor for ICUAW. However, the mechanisms underlying HG-induced respiratory muscle weakness are not known. Excessive reactive oxygen species (ROS) injure multiple tissues during HG, but only one study suggests that excessive ROS generation may be linked to HG-induced diaphragm weakness. We hypothesized that HG-induced diaphragm dysfunction is mediated by excessive superoxide generation and that administration of a specific superoxide scavenger, polyethylene glycol superoxide dismutase (PEG-SOD), would ameliorate these effects. Methods HG was induced in rats using streptozotocin (60 mg/kg intravenously) and the following groups assessed at two weeks: controls, HG, HG + PEG-SOD (2,000U/kg/d intraperitoneally for seven days), and HG + denatured (dn)PEG-SOD (2000U/kg/d intraperitoneally for seven days). PEG-SOD and dnPEG-SOD were administered on day 8, we measured diaphragm specific force generation in muscle strips, force-pCa relationships in single permeabilized fibers, contractile protein content and indices of oxidative stress. Results HG reduced diaphragm specific force generation, altered single fiber force-pCa relationships, depleted troponin T, and increased oxidative stress. PEG-SOD prevented HG-induced reductions in diaphragm specific force generation (for example 80 Hz force was 26.4 ± 0.9, 15.4 ± 0.9, 24.0 ± 1.5 and 14.9 ± 0.9 N/cm2 for control, HG, HG + PEG-SOD, and HG + dnPEG-SOD groups, respectively, P hyperglycemia-induced diaphragm dysfunction. This new mechanistic information could explain how HG alters diaphragm function during critical illness. PMID:24886999

  10. Comparison of the cis-bending and C-H stretching vibration on the reaction of C2H2+ with H2 using laser induced reactions.

    Science.gov (United States)

    Schlemmer, Stephan; Asvany, Oskar; Giesen, Thomas

    2005-04-07

    Laser induced reaction (LIR) of C2H2(+) + H2 in a 22-pole ion trap at 90 K has been employed to detect the v3 C-H stretching vibration and the v5 cis bending vibration of the acetylene parent ion using the wide tunability of the free electron laser FELIX. The vibrational frequency of the bending vibration, omega5, and the corresponding Renner-Teller parameter, epsilon5, are determined to be 710 cm(-1) and 0.03, respectively. These results differ quite substantially from previous experimental work but are in line with the most recent and advanced theoretical work. The dependence of the LIR-signal of the two vibrational modes is studied systematically with respect to the laser power, storage time, and number density of the hydrogen collision partner. A reaction scheme describing all steps involved in the LIR process is set up. The corresponding rate equation system is solved numerically. From this solution the lifetimes for the vibrational excited states, tau3 = (3 +/- 1) ms and t5 = (200 +/- 50) ms and the vibrational dipole moments micro3 = 0.19(2) D and micro2 = 0.21(2) D are determined under the assumption that the excited parent ion relaxes or reacts with a net rate coefficient equal to the Langevin limit. The lifetime for the C-H stretching vibration is in agreement with a previous LIR experiment and with ab initio calculations. C-H stretching turns out to be about an order of magnitude more efficient than bending in promoting hydrogen abstraction. This strong mode dependence is discussed on the basis of the energetics for hydrogen abstraction and a possible inhibition of complex formation in the entrance channel of the C2H2+..H2 collision system.

  11. [High speed cinematographic analysis of subglottal mucosal vibration during experimentally induced phonation in excised larynges].

    Science.gov (United States)

    Kurokawa, H

    1992-08-01

    Twenty-seven excised canine larynges and two excised human larynges fixed on a wall of a specially constructed glass box, were blown on and the subglottal mucosal vibrations were photographed using high speed cinematography from the tracheal side. Each film was repeatedly projected at normal speed and analyzed frame by frame. Mucosal upheaval appeared between the anterior commissure and the vocal process. The mucosal wave or "traveling wave" started from the mucosal upheaval and propagated medially and upward. The mucosal upheaval vibrated with a small amplitude and with an earlier phase than any other portion of the vocal fold. Increase of air flow resulted in increased amplitude of the free edge excursion. The mucosal upheaval seemed to shift more laterally after the increase of air flow. But judging from the positional relations between the mucosal upheaval and markers, the origin of the mucosal upheaval was the same despite the increase of air flow. After the increase of vocal fold tension by cricothyroid approximation, the mucosal wave occurred within the limited area near the vocal edge. The mucosal upheaval was located more medially as compared to the original position. The mucosal upheaval appeared on what was actually the superior portion of the vocal fold. Direct electrical stimulation of the thyroarytenoid muscle (TA) bulged the lower surface of the vocal fold medially, and narrowed the subglottic area surrounded by bilateral mucosal upheavals during vibration. The mucosal upheaval seemed to shift more medially after stimulation of TA, but combined with the movements of the marker, the mucosal upheaval appeared on a more inferior portion of the vocal fold compared to its position before the stimulation. Thus, a more dynamic mucosal wave appeared in the vertical direction. Histological examination revealed that the mucosal upheaval arose on the lower surface of the vocal fold, slightly above the area where the muscular layer came close to the epithelial

  12. The physiological determinants of drug-induced lysosomal stress resistance.

    Directory of Open Access Journals (Sweden)

    Tehetina Woldemichael

    Full Text Available Many weakly basic, lipophilic drugs accumulate in lysosomes and exert complex, pleiotropic effects on organelle structure and function. Thus, modeling how perturbations of lysosomal physiology affect the maintenance of lysosomal ion homeostasis is necessary to elucidate the key factors which determine the toxicological effects of lysosomotropic agents, in a cell-type dependent manner. Accordingly, a physiologically-based mathematical modeling and simulation approach was used to explore the dynamic, multi-parameter phenomenon of lysosomal stress. With this approach, parameters that are either directly involved in lysosomal ion transportation or lysosomal morphology were transiently altered to investigate their downstream effects on lysosomal physiology reflected by the changes they induce in lysosomal pH, chloride, and membrane potential. In addition, combinations of parameters were simultaneously altered to assess which parameter was most critical for recovery of normal lysosomal physiology. Lastly, to explore the relationship between organelle morphology and induced stress, we investigated the effects of parameters controlling organelle geometry on the restoration of normal lysosomal physiology following a transient perturbation. Collectively, our results indicate a key, interdependent role of V-ATPase number and membrane proton permeability in lysosomal stress tolerance. This suggests that the cell-type dependent regulation of V-ATPase subunit expression and turnover, together with the proton permeability properties of the lysosomal membrane, is critical to understand the differential sensitivity or resistance of different cell types to the toxic effects of lysosomotropic drugs.

  13. Metformin differentially activates ER stress signaling pathways without inducing apoptosis

    Directory of Open Access Journals (Sweden)

    Thomas Quentin

    2012-03-01

    Endoplasmic reticulum stress signaling (ERSS plays an important role in the pathogenesis of diabetes and heart disease. The latter is a common comorbidity of diabetes and worsens patient outcome. Results from clinical studies suggest beneficial effects of metformin – a widely used oral drug for the treatment of type 2 diabetes – on the heart of diabetic patients with heart failure. We therefore analyzed the effect of metformin on ERSS in primary rat cardiomyocytes. We found that metformin activates the PERK-ATF4 but not the ATF6 or IRE1-XBP1 branch in ERSS and leads to a strong upregulation of CHOP mRNA and protein. Surprisingly, long-term induction of CHOP by metformin is not accompanied by apoptosis even though CHOP is regarded to be a mediator of ER-stress-induced apoptosis. In conclusion, metformin induces distinct ER stress pathways in cardiomyocytes and our results indicate that CHOP is not necessarily a mediator of apoptosis. Metformin might exert its cardioprotective effect through selective activation of ERSS pathways in the cardiomyocyte.

  14. Metformin differentially activates ER stress signaling pathways without inducing apoptosis.

    Science.gov (United States)

    Quentin, Thomas; Steinmetz, Michael; Poppe, Andrea; Thoms, Sven

    2012-03-01

    Endoplasmic reticulum stress signaling (ERSS) plays an important role in the pathogenesis of diabetes and heart disease. The latter is a common comorbidity of diabetes and worsens patient outcome. Results from clinical studies suggest beneficial effects of metformin - a widely used oral drug for the treatment of type 2 diabetes - on the heart of diabetic patients with heart failure. We therefore analyzed the effect of metformin on ERSS in primary rat cardiomyocytes. We found that metformin activates the PERK-ATF4 but not the ATF6 or IRE1-XBP1 branch in ERSS and leads to a strong upregulation of CHOP mRNA and protein. Surprisingly, long-term induction of CHOP by metformin is not accompanied by apoptosis even though CHOP is regarded to be a mediator of ER-stress-induced apoptosis. In conclusion, metformin induces distinct ER stress pathways in cardiomyocytes and our results indicate that CHOP is not necessarily a mediator of apoptosis. Metformin might exert its cardioprotective effect through selective activation of ERSS pathways in the cardiomyocyte.

  15. 2.5D Finite/infinite Element Approach for Simulating Train-Induced Ground Vibrations

    Science.gov (United States)

    Yang, Y. B.; Hung, H. H.; Kao, J. C.

    2010-05-01

    The 2.5D finite/infinite element approach for simulating the ground vibrations by surface or underground moving trains will be briefly summarized in this paper. By assuming the soils to be uniform along the direction of the railway, only a two-dimensional profile of the soil perpendicular to the railway need be considered in the modeling. Besides the two in-plane degrees of freedom (DOFs) per node conventionally used for plane strain elements, an extra DOF is introduced to account for the out-of-plane wave transmission. The profile of the half-space is divided into a near field and a semi-infinite far field. The near field containing the train loads and irregular structures is simulated by the finite elements, while the far field covering the soils with infinite boundary by the infinite elements, by which due account is taken of the radiation effects for the moving loads. Enhanced by the automated mesh expansion procedure proposed previously by the writers, the far field impedances for all the lower frequencies are generated repetitively from the mesh created for the highest frequency considered. Finally, incorporated with a proposed load generation mechanism that takes the rail irregularity and dynamic properties of trains into account, an illustrative case study was performed. This paper investigates the vibration isolation effect of the elastic foundation that separates the concrete slab track from the underlying soil or tunnel structure. In addition, the advantage of the 2.5D approach was clearly demonstrated in that the three-dimensional wave propagation effect can be virtually captured using a two-dimensional finite/infinite element mesh. Compared with the conventional 3D approach, the present approach appears to be simple, efficient and generally accurate.

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

    Science.gov (United States)

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

    2017-02-01

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

  17. Wave-induced stresses and pore pressures near a mudline

    Directory of Open Access Journals (Sweden)

    Andrzej Sawicki

    2008-12-01

    Full Text Available Conventional methods for the determination of water-wave induced stresses inseabeds composed of granular soils are based on Biot-type models, in which the soilskeleton is treated as an elastic medium. Such methods predict effective stressesin the soil that are unacceptable from the physical point of view, as they permittensile stresses to occur near the upper surface of the seabed. Therefore, in thispaper the granular soil is assumed to behave as an elastic-ideally plastic material,with the Coulomb-Mohr yield criterion adopted to bound admissible stress states inthe seabed. The governing equations are solved numerically by a~finite differencemethod. The results of simulations, carried out for the case of time-harmonicwater waves, illustrate the depth distributions of the excess pore pressures and theeffective stresses in the seabed, and show the shapes of zones of soil in the plastic state.~In particular, the effects on the seabed behaviour of suchparameters as the degree of pore water saturation, the soil permeability, and theearth pressure coefficient, are illustrated.

  18. Driving-induced stress in urban college students.

    Science.gov (United States)

    Rasmussen, C; Knapp, T J; Garner, L

    2000-04-01

    Urban college student commuters (N = 407) were surveyed about their experiences with stress induced by driving. Of the participants 23.6% reported becoming angry at another driver more than once per day. They rated stress from other drivers as equal to the stress experienced during a college examination but gave slightly lower ratings to traffic congestion, road construction, and finding a parking place as sources of stress. Slow drivers, a child not restrained, and a vehicle following too closely were the highest rated annoying situations. Of participants, 21.6% had reported another driver to the police; nearly 22% said they carried a weapon for protection from other drivers (5.4% said a gun). Men were more than twice as likely as women to carry a weapon and three times as likely to carry a gun. Of the total sample, 19.1% feared being shot by another driver. Most participants (75.8%) said drivers were more aggressive and dangerous than they were five years ago.

  19. Stress-induced Ageing of Lithium-Ion Batteries.

    Science.gov (United States)

    Held, Marcel; Sennhauser, Urs

    2015-01-01

    Lithium-ion batteries are well established for use in portable consumer products and are increasingly used in high power electro-mobility and photovoltaic storage applications. In hybrid and plug-in electric vehicles degradation and useful lifetime at standard operation conditions are critical parameters in addition to performance and safety. Here stress-induced ageing of commercially available high power battery cells of the type A123 AHR32113M1 Ultra-B, consisting of a LiFePO(4) cathode and a graphite anode have been investigated. A usually accepted capacity loss for electric vehicles of 20% was reached after 8560 stress profiles corresponding to a driving distance of almost 200'000 km. Cycling with a stress profile applying constant power corresponding to the average power and energy of a full stress profile and starting at 60% state of charge showed a much faster capacity loss. Electric impedance measurements show the dependence of the capacity loss and constant phase element at low frequency, indicating Li-ion diffusion blocking in the cathode. Microscopic analysis of anode, separator, and cathode, shows defect formation in bulk material and at interfaces.

  20. The ER stress inducer DMC enhances TRAIL-induced apoptosis in glioblastoma

    NARCIS (Netherlands)

    van Roosmalen, Ingrid A. M.; Dos Reis, Carlos R; Setroikromo, Rita; Yuvaraj, Saravanan; Joseph, Justin V.; Tepper, Pieter G.; Kruyt, Frank A. E.; Quax, Wim J.

    2014-01-01

    Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumour in humans and is highly resistant to current treatment modalities. We have explored the combined treatment of the endoplasmic reticulum (ER) stress-inducing agent 2,5-dimethyl-celecoxib (DMC) and TNF-related

  1. [Exercise-induced shear stress: Physiological basis and clinical impact].

    Science.gov (United States)

    Rodríguez-Núñez, Iván; Romero, Fernando; Saavedra, María Javiera

    2016-01-01

    The physiological regulation of vascular function is essential for cardiovascular health and depends on adequate control of molecular mechanisms triggered by endothelial cells in response to mechanical and chemical stimuli induced by blood flow. Endothelial dysfunction is one of the major risk factors for cardiovascular disease, where an imbalance between synthesis of vasodilator and vasoconstrictor molecules is one of its main mechanisms. In this context, the shear stress is one of the most important mechanical stimuli to improve vascular function, due to endothelial mechanotransduction, triggered by stimulation of various endothelial mechanosensors, induce signaling pathways culminating in increased bioavailability of vasodilators molecules such as nitric oxide, that finally trigger the angiogenic mechanisms. These mechanisms allow providing the physiological basis for the effects of exercise on vascular health. In this review it is discussed the molecular mechanisms involved in the vascular response induced by shear stress and its impact in reversing vascular injury associated with the most prevalent cardiovascular disease in our population. Copyright © 2016 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

  2. Inflammatory Stress Potentiates Emodin-Induced Liver Injury in Rats

    Directory of Open Access Journals (Sweden)

    Can eTu

    2015-10-01

    Full Text Available Herbal medicines containing emodin, widely used for the treatment of hepatitis in clinic, have been reported with hepatotoxicity in individuals. A modest inflammatory stress potentiating liver injury has been linked to the idiosyncratic drug-induced liver injury (IDILI. In this study, we investigated the hypothesis that lipopolysaccharide (LPS interacts with emodin could synergize to cause liver injury in rats. Emodin (ranging from 20, 40 to 80 mg/kg, which is in the range of liver protection, was administered to rats, before LPS (2.8 mg/kg or saline vehicle treatment. The biochemical tests showed that non-toxic dosage of LPS coupled with emodin caused significant increases of plasma ALT and AST activities as compared to emodin alone treated groups (P<0.05. In addition, with LPS or emodin alone could not induce any changes in ALT and AST activity, as compared with the control group (0.5% CMC-Na treatment. Meanwhile, the plasma proinflammatory cytokines, TNF-α, IL-1β, and IL-6 increased significantly in the emodin/LPS groups compared to either emodin groups or the LPS (P<0.05. Histological analysis showed that liver damage was only found in emodin/LPS cotreatmented rat livers samples. These results indicate that non-toxic dosage of LPS potentiates the hepatotoxicity of emodin. This discovery raises the possibility that emodin and herbal medicines containing it may induce liver injury in the inflammatory stress even in their therapeutic dosages.

  3. Indium and indium tin oxide induce endoplasmic reticulum stress and oxidative stress in zebrafish (Danio rerio).

    Science.gov (United States)

    Brun, Nadja Rebecca; Christen, Verena; Furrer, Gerhard; Fent, Karl

    2014-10-07

    Indium and indium tin oxide (ITO) are extensively used in electronic technologies. They may be introduced into the environment during production, use, and leaching from electronic devices at the end of their life. At present, surprisingly little is known about potential ecotoxicological implications of indium contamination. Here, molecular effects of indium nitrate (In(NO3)3) and ITO nanoparticles were investigated in vitro in zebrafish liver cells (ZFL) cells and in zebrafish embryos and novel insights into their molecular effects are provided. In(NO3)3 led to induction of endoplasmic reticulum (ER) stress response, induction of reactive oxygen species (ROS) and induction of transcripts of pro-apoptotic genes and TNF-α in vitro at a concentration of 247 μg/L. In(NO3)3 induced the ER stress key gene BiP at mRNA and protein level, as well as atf6, which ultimately led to induction of the important pro-apoptotic marker gene chop. The activity of In(NO3)3 on ER stress induction was much stronger than that of ITO, which is explained by differences in soluble free indium ion concentrations. The effect was also stronger in ZFL cells than in zebrafish embryos. Our study provides first evidence of ER stress and oxidative stress induction by In(NO3)3 and ITO indicating a critical toxicological profile that needs further investigation.

  4. The Role of Stress-Induced Ligands in Immune Response

    Directory of Open Access Journals (Sweden)

    G.Seyda Seydel

    2011-02-01

    Full Text Available Natural killer (NK cells which are a component of the immune system are capable of killing tumor cells and virally infected cells. The activation of NK cells is regulated by the balance of activating and inhibitory surface receptors. NKG2D is one of the these activating receptors. The ligands of NKG2D are the human class I like molecules MICA and MICB which are encoded within the human MHC. MICA and MICB are not expressed on normal cells but up-regulated under condition of stress such as heat schock and viral infection. Therefore, NKG2D ligands are defined as stress-induced antigens. [Archives Medical Review Journal 2011; 20(1.000: 1-19

  5. Exaggerated haemodynamic and neural responses to involuntary contractions induced by whole-body vibration in normotensive obese versus lean women.

    Science.gov (United States)

    Dipla, Konstantina; Kousoula, Dimitra; Zafeiridis, Andreas; Karatrantou, Konstantina; Nikolaidis, Michalis G; Kyparos, Antonios; Gerodimos, Vassilis; Vrabas, Ioannis S

    2016-06-01

    What is the central question of this study? In obesity, the exaggerated blood pressure response to voluntary exercise is linked to hypertension, yet the mechanisms are not fully elucidated. We examined whether involuntary contractions elicit greater haemodynamic responses and altered neural control of blood pressure in normotensive obese versus lean women. What is the main finding and its importance? During involuntary contractions induced by whole-body vibration, there were augmented blood pressure and spontaneous baroreflex responses in obese compared with lean women. This finding is suggestive of an overactive mechanoreflex in the exercise-induced hypertensive response in obesity. Passive contractions did not elicit differential heart rate responses in obese compared with lean women, implying other mechanisms for the blunted heart rate response reported during voluntary exercise in obesity. In obesity, the exaggerated blood pressure (BP) response to exercise is linked to hypertension, yet the mechanisms are not fully elucidated. In this study, we examined whether involuntary mechanical oscillations, induced by whole-body vibration (WBV), elicit greater haemodynamic responses and altered neural control of BP in obese versus lean women. Twenty-two normotensive, premenopausal women (12 lean and 10 obese) randomly underwent a passive WBV (25 Hz) and a control protocol (similar posture without WVB). Beat-by-beat BP, heart rate, stroke volume, systemic vascular resistance, cardiac output, parasympathetic output (evaluated by heart rate variability) and spontaneous baroreceptor sensitivity (sBRS) were assessed. We found that during WBV, obese women exhibited an augmented systolic BP response compared with lean women that was correlated with body fat percentage (r = 0.77; P obese versus lean women, associated with a greater stroke volume index in obese women. Involuntary contractions did not elicit a differential magnitude of responses in heart rate, heart rate

  6. Aloin Protects Skin Fibroblasts from Heat Stress-Induced Oxidative Stress Damage by Regulating the Oxidative Defense System

    OpenAIRE

    Fu-Wei Liu; Fu-Chao Liu; Yu-Ren Wang; Hsin-I Tsai; Huang-Ping Yu

    2015-01-01

    Oxidative stress is commonly involved in the pathogenesis of skin damage induced by environmental factors, such as heat stress. Skin fibroblasts are responsible for the connective tissue regeneration and the skin recovery from injury. Aloin, a bioactive compound in Aloe vera, has been reported to have various pharmacological activities, such as anti-inflammatory effects. The aim of this study was to investigate the protective effect of aloin against heat stress-mediated oxidative stress in hu...

  7. A study on the evaluation of vibration effect and the development of vibration reduction method for Wolsung unit 1 main steam piping

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun; Kim, Yeon Whan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Tae Ryong; Park, Jin Ho [Korea Atomic Energy Research Inst., Daeduk (Korea, Republic of)

    1996-08-01

    The main steam piping of nuclear power plant which runs between steam generator and high pressure turbine has been experienced to have a severe effect on the safe operation of the plant due to the vibration induced by the steam flowing inside the piping. The imposed cyclic loads by the vibration could result in the degradation of the related structures such as connection parts between main instruments, valves, pipe supports and building. The objective of the study is to reduce the vibration level of Wolsung nuclear power plant unit 1 main steam pipeline by analyzing vibration characteristics of the piping, identifying sources of the vibration and developing a vibration reduction method .The location of the maximum vibration is piping between the main steam header and steam chest .The stress level was found to be within the allowable limit .The main vibration frequency was found to be 4{approx}6 Hz which is the same as the natural frequency from model test .A vibration reduction method using pipe supports of energy absorbing type(WEAR)is selected .The measured vibration level after WEAR installation was reduced about 36{approx}77% in displacement unit (author). 36 refs., 188 figs.

  8. Oxidative stress in NSC-741909-induced apoptosis of cancer cells

    Directory of Open Access Journals (Sweden)

    Huang Peng

    2010-04-01

    Full Text Available Abstract Background NSC-741909 is a novel anticancer agent that can effectively suppress the growth of several cell lines derived from lung, colon, breast, ovarian, and kidney cancers. We recently showed that NSC-741909-induced antitumor activity is associated with sustained Jun N-terminal kinase (JNK activation, resulting from suppression of JNK dephosphorylation associated with decreased protein levels of MAPK phosphatase-1. However, the mechanisms of NSC-741909-induced antitumor activity remain unclear. Because JNK is frequently activated by oxidative stress in cells, we hypothesized that reactive oxygen species (ROS may be involved in the suppression of JNK dephosphorylation and the cytotoxicity of NSC-741909. Methods The generation of ROS was measured by using the cell-permeable nonfluorescent compound H2DCF-DA and flow cytometry analysis. Cell viability was determined by sulforhodamine B assay. Western blot analysis, immunofluorescent staining and flow cytometry assays were used to determine apoptosis and molecular changes induced by NSC-741909. Results Treatment with NSC-741909 induced robust ROS generation and marked MAPK phosphatase-1 and -7 clustering in NSC-741909-sensitive, but not resistant cell lines, in a dose- and time-dependent manner. The generation of ROS was detectable as early as 30 min and ROS levels were as high as 6- to 8-fold above basal levels after treatment. Moreover, the NSC-741909-induced ROS generation could be blocked by pretreatment with antioxidants, such as nordihydroguaiaretic acid, aesculetin, baicalein, and caffeic acid, which in turn, inhibited the NSC-741909-induced JNK activation and apoptosis. Conclusion Our results demonstrate that the increased ROS production was associated with NSC-741909-induced antitumor activity and that ROS generation and subsequent JNK activation is one of the primary mechanisms of NSC-741909-mediated antitumor cell activity.

  9. Acrolein induces endoplasmic reticulum stress and causes airspace enlargement.

    Directory of Open Access Journals (Sweden)

    Yoshiaki Kitaguchi

    Full Text Available BACKGROUND: Given the relative abundance and toxic potential of acrolein in inhaled cigarette smoke, it is surprising how little is known about the pulmonary and systemic effects of acrolein. Here we test the hypothesis whether systemic administration of acrolein could cause endoplasmic reticulum (ER stress, and lung cell apoptosis, leading to the enlargement of the alveolar air spaces in rats. METHODS: Acute and chronic effects of intraperitoneally administered acrolein were tested. Mean alveolar airspace area was measured by using light microscopy and imaging system software. TUNEL staining and immunohistochemistry (IHC for active caspase 3 and Western blot analysis for active caspase 3, and caspase 12 were performed to detect apoptosis. The ER-stress related gene expression in the lungs was determined by Quantitative real-time PCR analysis. Acrolein-protein adducts in the lung tissue were detected by IHC. RESULTS: Acute administration of acrolein caused a significant elevation of activated caspase 3, upregulation of VEGF expression and induced ER stress proteins in the lung tissue. The chronic administration of acrolein in rats led to emphysematous lung tissue remodeling. TUNEL staining and IHC for cleaved caspase 3 showed a large number of apoptotic septal cells in the acrolein-treated rat lungs. Chronic acrolein administration cause the endoplasmic reticulum stress response manifested by significant upregulation of ATF4, CHOP and GADd34 expression. In smokers with COPD there was a considerable accumulation of acrolein-protein adducts in the inflammatory, airway and vascular cells. CONCLUSIONS: Systemic administration of acrolein causes endoplasmic reticulum stress response, lung cell apoptosis, and chronic administration leads to the enlargement of the alveolar air spaces and emphysema in rats. The substantial accumulation of acrolein-protein adducts in the lungs of COPD patients suggest a role of acrolein in the pathogenesis of emphysema.

  10. Circus, software for computation of flow induced vibrations in piping system. General purpose; Code circus, logiciel pour la prediction des vibrations sous ecoulement. Une presentation generale

    Energy Technology Data Exchange (ETDEWEB)

    Seligmann, D.

    1996-11-01

    This paper is a presentation of the code CIRCUS version 2. CIRCUS deals with the hydraulic, acoustic and vibratory behaviour of piping systems under acoustic loads. CIRCUS first computes permanent mean-flow, and associated acoustic loads. It then determines the acoustic and vibration response along the piping system. The CIRCUS software is used at EDF to check the design of piping system and to investigate solutions in case of damage or troubleshooting. (author). 10 refs.

  11. Scientific Exploration of Induced SeisMicity and Stress (SEISMS)

    Science.gov (United States)

    Savage, Heather M.; Kirkpatrick, James D.; Mori, James J.; Brodsky, Emily E.; Ellsworth, William L.; Carpenter, Brett M.; Chen, Xiaowei; Cappa, Frédéric; Kano, Yasuyuki

    2017-11-01

    Several major fault-drilling projects have captured the interseismic and postseismic periods of earthquakes. However, near-field observations of faults immediately before and during an earthquake remain elusive due to the unpredictable nature of seismicity. The Scientific Exploration of Induced SeisMicity and Stress (SEISMS) workshop met in March 2017 to discuss the value of a drilling experiment where a fault is instrumented in advance of an earthquake induced through controlled fluid injection. The workshop participants articulated three key issues that could most effectively be addressed by such an experiment: (1) predictive understanding of the propensity for seismicity in reaction to human forcing, (2) identification of earthquake nucleation processes, and (3) constraints on the factors controlling earthquake size. A systematic review of previous injection experiments exposed important observational gaps in all of these areas. The participants discussed the instrumentation and technological needs as well as faults and tectonic areas that are feasible from both a societal and scientific standpoint.

  12. Identification of 30 protein species involved in replicative senescence and stress-induced premature senescence

    DEFF Research Database (Denmark)

    Dierick, Jean François; Kalume, Dário E; Wenders, Frédéric

    2002-01-01

    Exposure of human proliferative cells to subcytotoxic stress triggers stress-induced premature senescence (SIPS) which is characterized by many biomarkers of replicative senescence. Proteomic comparison of replicative senescence and stress-induced premature senescence indicates that, at the level...... of protein expression, stress-induced premature senescence and replicative senescence are different phenotypes sharing however similarities. In this study, we identified 30 proteins showing changes of expression level specific or common to replicative senescence and/or stress-induced premature senescence....... These changes affect different cell functions, including energy metabolism, defense systems, maintenance of the redox potential, cell morphology and transduction pathways....

  13. Sirtuin1 single nucleotide polymorphism (A2191G is a diagnostic marker for vibration-induced white finger disease

    Directory of Open Access Journals (Sweden)

    Voelter-Mahlknecht Susanne

    2012-10-01

    Full Text Available Abstract Background Vibration-induced white finger disease (VWF, also known as hand-arm vibration syndrome, is a secondary form of Raynaud’s disease, affecting the blood vessels and nerves. So far, little is known about the pathogenesisof the disease. VWF is associated with an episodic reduction in peripheral blood flow. Sirtuin 1, a class III histone deacetylase, has been described to regulate the endothelium dependent vasodilation by targeting endothelial nitric oxide synthase. We assessed Sirt1single nucleotide polymorphisms in patients with VWF to further elucidate the role of sirtuin 1 in the pathogenesis of VWF. Methods Peripheral blood samples were obtained from 74 patients with VWF (male 93.2%, female 6.8%, median age 53 years and from 317 healthy volunteers (gender equally distributed, below 30 years of age. Genomic DNA was extracted from peripheral blood mononuclear cells and screened for potential Sirt1single nucleotide polymorphisms. Four putative genetic polymorphisms out of 113 within the Sirt1 genomic region (NCBI Gene Reference: NM_012238.3 were assessed. Allelic discrimination was performed by TaqMan-polymerasechainreaction-based allele-specific genotyping single nucleotide polymorphism assays. Results Sirt1single nucleotide polymorphism A2191G (Assay C_25611590_10, rs35224060 was identified within Sirt1 exon 9 (amino acid position 731, Ile → Val, with differing allelic frequencies in the VWF population (A/A: 70.5%, A/G: 29.5%, G/G: 0% and the control population (A/A: 99.7%, A/G: 0.3%, G/G: 0.5%, with significance levels of P U test (two-tailed P t-test and Chi-square test with Yates correction (all two-tailed: P Conclusion We identified theSirt1A2191Gsingle nucleotide polymorphism as a diagnostic marker for VWF.

  14. Performance enhancement of a rotational energy harvester utilizing wind-induced vibration of an inclined stay cable

    Science.gov (United States)

    Kim, In-Ho; Jang, Seon-Jun; Jung, Hyung-Jo

    2013-07-01

    In this paper, an innovative strategy for improving the performance of a recently developed rotational energy harvester is proposed. Its performance can be considerably enhanced by replacing the electromagnetic induction part, consisting of moving permanent magnets and a fixed solenoid coil, with a moving mass and a rotational generator (i.e., an electric motor). The proposed system is easily tuned to the natural frequency of a target structure using the position change of a proof mass. Owing to the high efficiency of the rotational generator, the device can more effectively harness electrical energy from the wind-induced vibration of a stay cable. Also, this new configuration makes the device more compact and geometrically tunable. In order to validate the effectiveness of the new configuration, a series of laboratory and field tests are carried out with the prototype of the proposed device, which is designed and fabricated based on the dynamic characteristics of the vibration of a stay cable installed in an in-service cable-stayed bridge. From the field test, it is observed that the normalized output power of the proposed system is 35.67 mW (m s-2)-2, while that of the original device is just 5.47 mW (m s-2)-2. These results show that the proposed device generates much more electrical energy than the original device. Moreover, it is verified that the proposed device can generate sufficient electricity to power a wireless sensor node placed on a cable under gentle-moderate wind conditions.

  15. DHA-induced stress response in human colon cancer cells - Focus on oxidative stress and autophagy.

    Science.gov (United States)

    Pettersen, Kristine; Monsen, Vivi Talstad; Hakvåg Pettersen, Caroline Hild; Overland, Hilde Bremseth; Pettersen, Grete; Samdal, Helle; Tesfahun, Almaz Nigatu; Lundemo, Anne Gøril; Bjørkøy, Geir; Schønberg, Svanhild A

    2016-01-01

    Polyunsaturated fatty acids (PUFAs) are important constituents of the diet and health benefits of omega-3/n-3 PUFAs, especially eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) have been well documented in relation to several diseases. Increasing evidence suggests that n-3 PUFAs may have anticancer activity and improve the effect of conventional cancer therapy. The mechanisms behind these effects are still unclear and need to be elucidated. We have examined the DHA-induced stress response in two human colon cancer cell lines, SW620 and Caco-2. SW620 cells are growth-inhibited at early time points by DHA, while the growth of Caco-2 cells almost remains unaffected by the same treatment. Gene expression analysis of SW620 cells treated with DHA revealed changes at early time points; transcripts involved in oxidative stress and autophagy were among the first to be differentially expressed. We find that oxidative stress is induced in both cell lines, although at different time points and to different extent. DHA induced nuclear translocation of the oxidative stress sensor NFE2L2 in both cell lines, indicating an induction of an anti-oxidative response. However, vitamin E did not counteract ROS-production or the translocation of NFE2L2 to the nucleus. Neither vitamin E nor the antioxidants butylated hydoxyanisole (BHA) and butylated hydoxytoluene (BHT) did affect the growth inhibition in SW620 cells after DHA-treatment. Also, siRNA-mediated down-regulation of NFE2L2 did not sensitize SW620 and Caco-2 cells to DHA. These results indicate that oxidative stress response is not the cause of DHA-induced cytotoxicity in SW620 cells. Using biochemical and imaging based functional assays, we found a low basal level of autophagy and no increase in autophagic flux after adding DHA to the SW620 cells. However, Caco-2 cells displayed a higher level of autophagy, both in the absence and presence of DHA. Inhibition of autophagy by siRNA mediated knock down

  16. Exploratory electromyography in the study of vibration-induced white finger in rock drillers

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, D.S.; Barwick, D.D.; Petrie, A.

    1982-02-01

    Electrophysiological observations made in the hands of a group of 16 rock-drillers were compared with 15 controls. Motor and sensory conduction velocities in the median and ulnar nerves together with the latency, duration, and amplitude of the evoked action potentials were measured. The differences between the groups were statistically significant mainly in latency, duration, and amplitude, especially of the sensory action potentials. Measurement of the conduction velocities, in general, proved to be less sensitive, and the only significant change observed was in the sensory conduction velocity in the median nerve when the first digit in the right hand was stimulated. The most interesting result was evidence of an increased prevalence of possible carpal tunnel syndrome in the exposed (44% compared with 7% in the control group). A similar set of data, but exclusively sensory and not standardised for age and sex, was obtained from 25 university students for comparison with the assigned groups. The results showed that apart from sensory duration the control group had values that were closest to the students while the vibration group had values furthest away.

  17. Prediction of flow induced sound and vibration of periodically stiffened plates.

    Science.gov (United States)

    Maxit, Laurent; Denis, Vivien

    2013-01-01

    Stiffened structures excited by the turbulent boundary layer (TBL) occur very frequently in engineering applications; for instance, in the wings of airplanes or the pressure hulls of submarines. To improve knowledge of the interaction between stiffened structures and TBL, this paper deals with the modeling of infinite periodically stiffened plates excited by TBL. The mathematical formulation of the problem is well-established in the literature. The originality of the present work relies on the use of a wavenumber-point reciprocity technique for evaluating the response of the plate to convected harmonic pressure waves. It follows a methodology for estimating the vibro-acoustic response of the plate excited by the TBL from the wall pressure spectrum and its displacements in the wavenumber space due to point excitations located at the receiving positions. The computing process can be reduced to the numerical integration of an analytical expression in the case of a periodically stiffened plate. An application to a naval test case highlights the effect of Bloch-Floquet waves on the vibrations of the plate and its radiated pressure in the fluid.

  18. Numerical simulation of vortex induced vibrations and its control by suction and blowing

    National Research Council Canada - National Science Library

    Muralidharan, K; Muddada, Sridhar; Patnaik, B.S.V

    2013-01-01

    .... and structural parameters such as, mass ratio, frequency ratio, damping ratio, etc. When a structure is flexibly mounted, the Karman vortex street formed behind the structure gives rise to vortex induced oscillations...

  19. Imagery Scripts and a Computerized Subtraction Stress Task Both Induce Stress in Methamphetamine Users: A Controlled Laboratory Study

    Directory of Open Access Journals (Sweden)

    Kathleen J. Garrison

    2010-01-01

    Full Text Available Patients treated for methamphetamine (MA dependence have a high rate of relapse, and stress is thought to play a key role. We sought to develop a computerized procedure for experimentally inducing stress in MA users. In a within-subjects design, we compared a computerized subtraction stress task (SST to personalized stress-imagery scripts and a control condition (neutral imagery in 9 former MA users, recruited in San Francisco in 2006–2007. We assessed blood hormone levels, anxiety and craving for MA on visual analog scales, and the Positive and Negative Affect Schedule and made linear mixed-effects models to analyze the results. Both the SST and stress scripts were effective in inducing self-report markers of stress in MA users. Because the SST is easily reproducible and requires less time of staff and participants, it may be a useful alternative for measuring stress reactivity in drug users.

  20. Effects of induced vibrations on the explosion hazard in coal seams; Einfluss von induzierten Schwingungen auf die Schlaggefahr in einem Kohlefloez

    Energy Technology Data Exchange (ETDEWEB)

    Guserle, S.

    2001-07-01

    The effects of induced vibrations on the explosion hazard in a coal seam is investigated. Vibration propagation in the seam is analyzed by two theoretical models, which take into account the vibration damping and the loss resulting from geometric dispersion, respectively. The results are compared with vibration amplitudes measured in model experiments. It is found that vibration induction will increase the explosion hazard in general but will reduce the intensity of explosions at the same time. [German] In dieser Arbeit wird der Einfluss einer Schwingungserregung auf die Schlaggefahr in einem Kohlefloez untersucht. Mittels zweier theoretischer Modelle wird die Schwingungsausbreitung im Floez analysiert. Ein Modell beruecksichtigt die Schwingungsdaempfung, das andere den Verlust infolge geometrischer Dispersion. Die Rechenergebnisse werden mit den in Modellversuchen gemessenen Schwingungsamplituden verglichen. In systematisch durchgefuehrten Modell-Versuchsreihen wird geprueft, wie die kritische Schlaglast und die Schlagheftigkeit (hier gemessen in Form der bei einem solchen Schlag freigesetzten elastischen Energie) von der Erregungsfrequenz, der Erregungsrichtung und der Steifigkeit des Modellnebengesteins abhaengen. Es zeigt sich, dass die Schwingungsinduzierung generell zu einer Erhoehung der Schlaggefahr, zum Teil aber zu einer erheblichen Reduktion der Heftigkeit eines solchen Schlages fuehrt. (orig.)

  1. Vortex-induced vibration for an isolated circular cylinder under the wake interference of an oscillating airfoil: Part II. Single degree of freedom

    Science.gov (United States)

    Zhang, G. Q.; Ji, L. C.; Hu, X.

    2017-04-01

    The vortex-induced vibration behind an isolated cylinder under the wake interference of an oscillating airfoil at different oscillating frequencies and amplitudes have been studied numerically. Our previous research [11] mainly focused on the two degree of freedom vibration problem, several types of the phase portraits of the displacement have been newly found, including the "half -8″ and "cone-net" types as reduced velocity increases. At present, we have continued the research to the single degree of freedom vibration, the corresponding results had been found that under the wake of the free steady flow, as the reduced velocity increases, the phase portraits displacements of the single degree of freedom vibrating cylinder will begin to rotate counterclockwise from the first and third quadrants to the second and fourth quadrants in a Cartesian coordinate system. Under the wake of the oscillating airfoil, the single bending curve and the single closed orbit (double "8-shape" like) of the displacements are newly found in the drag and thrust producing cases respectively. Except this, the two triplets of vortices have also been newly found in the pair and single plus pair wakes at each cycle. The vorticity dynamics behind the vibrating cylinder together with the corresponding force variations have also been obtained computationally and analyzed in details.

  2. The diagnosis and treatment of stress-induced anovulation.

    Science.gov (United States)

    Berga, S L; Loucks, T L

    2005-02-01

    Behaviors that activate the hypothalamic-pituitary-adrenal (HPA) axis or suppress the hypothalamic-pituitary-thyroidal (HPT) axis can disrupt the hypothalamic-pituitary-gonadal (HPG) axis in women and men. Individuals with functional hypothalamic hypogonadism typically engage in a combination of behaviors that serve as psychogenic stressors and present metabolic challenges. Complete recovery of gonadal function depends upon restoration of the HPA and HPT axes. Hormone replacement strategies have limited benefit because they do not promote recovery from these allostatic endocrine adjustments in the HPA and HPT axes. Indeed, the rationale for the use of sex steroid replacement is based on the erroneous assumption that functional forms of hypothalamic hypogonadism represent only an alteration in the hypothalamic-pituitary-ovarian (HPO) axis. Further, use of sex hormones masks deficits that accrue from altered HPA and HPT function. Long-term deleterious consequences of stress-induced anovulation may include an increased risk of cardiovascular disease, osteoporosis, depression, other psychiatric conditions, and dementia. Although fertility can be restored with exogenous administration of gonadotropins or pulsatile GnRH, fertility management alone will not permit recovery of the HPA and HPT axes. Failure to reverse the hormonal milieu induced by stress may increase the likelihood of poor obstetrical, fetal, or neonatal outcomes. In contrast, behavioral and psychological interventions that address problematic behaviors and attitudes have the potential to permit resumption of ovarian function along with recovery of the HPT and HPA axes. Full endocrine recovery offers better individual, maternal, and child health.

  3. Effects of Kombucha on oxidative stress induced nephrotoxicity in rats.

    Science.gov (United States)

    Gharib, Ola Ali

    2009-11-27

    Trichloroethylene (TCE) may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radical scavenging enzymes. Twenty male albino rats were divided into four groups: (1) the control group treated with vehicle, (2) Kombucha (KT)-treated group, (3) TCE-treated group and (4) KT/TCE-treated group. Kidney lipid peroxidation, glutathione content, nitric oxide (NO) and total blood free radical concentrations were evaluated. Serum urea, creatinine level, gamma-glutamyl transferase (GGT) and lactate dehydrogenase (LDH) activities were also measured. TCE administration increased the malondiahyde (MDA) and NO contents in kidney, urea and creatinine concentrations in serum, total free radical level in blood and GGT and LDH activities in serum, whereas it decreased the glutathione (GSH) level in kidney homogenate. KT administration significantly improved lipid peroxidation and oxidative stress induced by TCE. The present study indicates that Kombucha may repair damage caused by environmental pollutants such as TCE and may be beneficial to patient suffering from renal impairment.

  4. Effects of Kombucha on oxidative stress induced nephrotoxicity in rats

    Directory of Open Access Journals (Sweden)

    Gharib Ola

    2009-11-01

    Full Text Available Abstract Background Trichloroethylene (TCE may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radical scavenging enzymes. Methods Twenty male albino rats were divided into four groups: (1 the control group treated with vehicle, (2 Kombucha (KT-treated group, (3 TCE-treated group and (4 KT/TCE-treated group. Kidney lipid peroxidation, glutathione content, nitric oxide (NO and total blood free radical concentrations were evaluated. Serum urea, creatinine level, gamma-glutamyl transferase (GGT and lactate dehydrogenase (LDH activities were also measured. Results TCE administration increased the malondiahyde (MDA and NO contents in kidney, urea and creatinine concentrations in serum, total free radical level in blood and GGT and LDH activities in serum, whereas it decreased the glutathione (GSH level in kidney homogenate. KT administration significantly improved lipid peroxidation and oxidative stress induced by TCE. Conclusion The present study indicates that Kombucha may repair damage caused by environmental pollutants such as TCE and may be beneficial to patient suffering from renal impairment.

  5. Vitiligo: How do oxidative stress-induced autoantigens trigger autoimmunity?

    Science.gov (United States)

    Xie, Heng; Zhou, Fubo; Liu, Ling; Zhu, Guannan; Li, Qiang; Li, Chunying; Gao, Tianwen

    2016-01-01

    Vitiligo is a common depigmentation disorder characterized by a loss of functional melanocytes and melanin from epidermis, in which the autoantigens and subsequent autoimmunity caused by oxidative stress play significant roles according to hypotheses. Various factors lead to reactive oxygen species (ROS) overproduction in the melanocytes of vitiligo: the exogenous and endogenous stimuli that cause ROS production, low levels of enzymatic and non-enzymatic antioxidants, disturbed antioxidant pathways and polymorphisms of ROS-associated genes. These factors synergistically contribute to the accumulation of ROS in melanocytes, finally leading to melanocyte damage and the production of autoantigens through the following ways: apoptosis, accumulation of misfolded peptides and cytokines induced by endoplasmic reticulum stress as well as the sustained unfolded protein response, and an 'eat me' signal for phagocytic cells triggered by calreticulin. Subsequently, autoantigens presentation and dendritic cells maturation occurred mediated by the release of antigen-containing exosomes, adenosine triphosphate and melanosomal autophagy. With the involvement of inducible heat shock protein 70, cellular immunity targeting autoantigens takes the essential place in the destruction of melanocytes, which eventually results in vitiligo. Several treatments, such as narrow band ultraviolet, quercetin and α-melanophore-stimulating hormone, are reported to be able to lower ROS thereby achieving repigmentation in vitiligo. In therapies targeting autoimmunity, restore of regulatory T cells is absorbing attention, in which narrow band ultraviolet also plays a role. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. Rapamycin alleviates oxidative stress-induced damage in rat erythrocytes.

    Science.gov (United States)

    Singh, Abhishek Kumar; Singh, Sandeep; Garg, Geetika; Rizvi, Syed Ibrahim

    2016-10-01

    An imbalanced cellular redox system promotes the production of reactive oxygen species (ROS) that may lead to oxidative stress-mediated cell death. Erythrocytes are the best-studied model of antioxidant defense mechanism. The present study was undertaken to investigate the effect of the immunosuppressant drug rapamycin, an inducer of autophagy, on redox balance of erythrocytes and blood plasma of oxidatively challenged rats. Male Wistar rats were oxidatively challenged with HgCl2 (5 mg/kg body mass (b.m.)). A significant (p membrane redox system (PMRS), intracellular Ca2+ influx, lipid peroxidation (LPO), osmotic fragility, plasma protein carbonyl (PCO) content, and plasma advanced oxidation protein products (AOPP) and simultaneously significant reduction in glutathione (GSH) level and ferric reducing ability of plasma (FRAP) were observed in rats exposed to HgCl2. Furthermore, rapamycin (0.5 mg/kg b.m.) provided significant protection against HgCl2-induced alterations in rat erythrocytes and plasma by reducing ROS production, PMRS activity, intracellular Ca2+ influx, LPO, osmotic fragility, PCO content, and AOPP and also restored the level of antioxidant GSH and FRAP. Our observations provide evidence that rapamycin improves redox status and attenuates oxidative stress in oxidatively challenged rats. Our data also demonstrate that rapamycin is a comparatively safe immunosuppressant drug.

  7. Oxidative Stress in Fish induced by Environmental Pollutants

    Directory of Open Access Journals (Sweden)

    Anton Kováčik

    2017-05-01

    Full Text Available Environmental pollutants represent a risk factor for human and animals in all areas of occurrence. Environmental pollution caused by anthropogenic activities is a major problem in many countries. Numbers of studies deals with cumulation of xenobiotics in tissues but not all respond to the real impact on living organisms. Freshwater fishes are exposed to several anthropogenic contaminants. The most commonly studied are three metals: mercury (Hg, lead (Pb, cadmium (Cd. These contaminants could have several impacts to oxidative stress. In the normal healthy cell, ROS and pro-oxidant products are detoxified by antioxidant defences. Redox-active or Redox-inactive metals may cause an increase in production of reactive oxygen species (ROS. Mercury has a high affinity for thiol groups, and can non-specifically affect several enzymes, e. g. GSH (glutathione, which can induce GSH depletion and oxidative stress in tissue, also can induce lipid peroxidation, and mitochondrial dysfunction. The toxicity of Cd to aquatic species depends on speciation, with the free ion, Cd2+ concentration being proportional to bioavailability. Cadmium toxicity worsened of Ca, Na, and Mg ions homeostasis. Lead can be toxic to nervous and skeletal systems; at cellular level can cause apoptosis, also can affect mitochondria, neurotransmitters, and can substitute for Ca.

  8. The 100S ribosome: ribosomal hibernation induced by stress.

    Science.gov (United States)

    Yoshida, Hideji; Wada, Akira

    2014-01-01

    One of the most important cellular events in all organisms is protein synthesis (translation), which is catalyzed by ribosomes. The regulation of translational activity is dependent on the environmental situation of the cell. A decrease in overall translation under stress conditions is mainly accompanied by the formation of functionally inactive 100S ribosomes in bacteria. The 100S ribosome is a dimer of two 70S ribosomes that is formed through interactions between their 30S subunits. Two mechanisms of 100S ribosome formation are known: one involving ribosome modulation factor (RMF) and short hibernation promoting factor (HPF) in a part of Gammaproteobacteria including Escherichia coli, and the other involving only long HPF in the majority of bacteria. The expression of RMF is regulated by ppGpp and cyclic AMP-cAMP receptor protein (cAMP-CRP) induced by amino acid starvation and glucose depletion, respectively. When stress conditions are removed, the 100S ribosome immediately dissociates into the active 70S ribosomes by releasing RMF. The stage in the ribosome cycle at which the ribosome loses translational activity is referred to as 'Hibernation'. The lifetime of cells that cannot form 100S ribosomes by deletion of the rmf gene is shorter than that of parental cells under stress conditions in E. coli. This fact indicates that the interconversion system between active 70S ribosomes and inactive 100S ribosomes is an important survival strategy for bacteria. © 2014 John Wiley & Sons, Ltd.

  9. p53 as a retrovirus-induced oxidative stress modulator.

    Science.gov (United States)

    Kim, Soo Jin; Wong, Paul K Y

    2015-01-01

    Infection of astrocytes by the neuropathogenic mutant of Moloney murine leukemia virus, ts1, exhibits increased levels of reactive oxygen species (ROS) and signs of oxidative stress compared with uninfected astrocytes. Previously, we have demonstrated that ts1 infection caused two separate events of ROS upregulation. The first upregulation occurs during early viral establishment in host cells and the second during the virus-mediated apoptotic process. In this study, we show that virus-mediated ROS upregulation activates the protein kinase, ataxia telangiectasia mutated, which in turn phosphorylates serine 15 on p53. This activation of p53 however, is unlikely associated with ts1-induced cell death. Rather p53 appears to be involved in suppressing intracellular ROS levels in astrocytes under oxidative stress. The activated p53 appears to delay retroviral gene expression by suppressing NADPH oxidase, a superoxide-producing enzyme. These results suggest that p53 plays a role as a retrovirus-mediated oxidative stress modulator. © 2015 The Authors.

  10. Programming stress-induced altruistic death in engineered bacteria

    Science.gov (United States)

    Tanouchi, Yu; Pai, Anand; Buchler, Nicolas E; You, Lingchong

    2012-01-01

    Programmed death is often associated with a bacterial stress response. This behavior appears paradoxical, as it offers no benefit to the individual. This paradox can be explained if the death is ‘altruistic': the killing of some cells can benefit the survivors through release of ‘public goods'. However, the conditions where bacterial programmed death becomes advantageous have not been unambiguously demonstrated experimentally. Here, we determined such conditions by engineering tunable, stress-induced altruistic death in the bacterium Escherichia coli. Using a mathematical model, we predicted the existence of an optimal programmed death rate that maximizes population growth under stress. We further predicted that altruistic death could generate the ‘Eagle effect', a counter-intuitive phenomenon where bacteria appear to grow better when treated with higher antibiotic concentrations. In support of these modeling insights, we experimentally demonstrated both the optimality in programmed death rate and the Eagle effect using our engineered system. Our findings fill a critical conceptual gap in the analysis of the evolution of bacterial programmed death, and have implications for a design of antibiotic treatment. PMID:23169002

  11. Simultaneous determination of the residual stress, elastic modulus, density and thickness of ultrathin film utilizing vibrating doubly clamped micro-/nanobeams

    Energy Technology Data Exchange (ETDEWEB)

    Stachiv, Ivo, E-mail: stachiv@fzu.cz [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan (China); Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic); Kuo, Chih-Yun [Tzu-Chi University, Hualian City, Hualian, Taiwan (China); Fang, Te-Hua [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan (China); Mortet, Vincent [Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic)

    2016-04-15

    Measurement of ultrathin film thickness and its basic properties can be highly challenging and time consuming due to necessity of using several very sophisticated devices. Here, we report an easy accessible resonant based method capable to simultaneously determinate the residual stress, elastic modulus, density and thickness of ultrathin film coated on doubly clamped micro-/nanobeam. We show that a general dependency of the resonant frequencies on the axial load is also valid for in-plane vibrations, and the one depends only on the considered vibrational mode. As a result, we found that the film elastic modulus, density and thickness can be evaluated from two measured in-plane and out-plane fundamental resonant frequencies of micro-/nanobeam with and without film under different prestress forces. Whereas, the residual stress can be determined from two out-plane (in-plane) measured consecutive resonant frequencies of beam with film under different prestress forces without necessity of knowing film and substrate properties and dimensions. Moreover, we also reveal that the common uncertainties in force (and thickness) determination have a negligible (and minor) impact on the determined film properties. The application potential of the present method is illustrated on the beam made of silicon and SiO{sub 2} with deposited 20 nm thick AlN and 40 nm thick Au thin films, respectively.

  12. Simultaneous determination of the residual stress, elastic modulus, density and thickness of ultrathin film utilizing vibrating doubly clamped micro-/nanobeams

    Directory of Open Access Journals (Sweden)

    Ivo Stachiv

    2016-04-01

    Full Text Available Measurement of ultrathin film thickness and its basic properties can be highly challenging and time consuming due to necessity of using several very sophisticated devices. Here, we report an easy accessible resonant based method capable to simultaneously determinate the residual stress, elastic modulus, density and thickness of ultrathin film coated on doubly clamped micro-/nanobeam. We show that a general dependency of the resonant frequencies on the axial load is also valid for in-plane vibrations, and the one depends only on the considered vibrational mode. As a result, we found that the film elastic modulus, density and thickness can be evaluated from two measured in-plane and out-plane fundamental resonant frequencies of micro-/nanobeam with and without film under different prestress forces. Whereas, the residual stress can be determined from two out-plane (in-plane measured consecutive resonant frequencies of beam with film under different prestress forces without necessity of knowing film and substrate properties and dimensions. Moreover, we also reveal that the common uncertainties in force (and thickness determination have a negligible (and minor impact on the determined film properties. The application potential of the present method is illustrated on the beam made of silicon and SiO2 with deposited 20 nm thick AlN and 40 nm thick Au thin films, respectively.

  13. Simultaneous determination of the residual stress, elastic modulus, density and thickness of ultrathin film utilizing vibrating doubly clamped micro-/nanobeams

    Science.gov (United States)

    Stachiv, Ivo; Kuo, Chih-Yun; Fang, Te-Hua; Mortet, Vincent

    2016-04-01

    Measurement of ultrathin film thickness and its basic properties can be highly challenging and time consuming due to necessity of using several very sophisticated devices. Here, we report an easy accessible resonant based method capable to simultaneously determinate the residual stress, elastic modulus, density and thickness of ultrathin film coated on doubly clamped micro-/nanobeam. We show that a general dependency of the resonant frequencies on the axial load is also valid for in-plane vibrations, and the one depends only on the considered vibrational mode. As a result, we found that the film elastic modulus, density and thickness can be evaluated from two measured in-plane and out-plane fundamental resonant frequencies of micro-/nanobeam with and without film under different prestress forces. Whereas, the residual stress can be determined from two out-plane (in-plane) measured consecutive resonant frequencies of beam with film under different prestress forces without necessity of knowing film and substrate properties and dimensions. Moreover, we also reveal that the common uncertainties in force (and thickness) determination have a negligible (and minor) impact on the determined film properties. The application potential of the present method is illustrated on the beam made of silicon and SiO2 with deposited 20 nm thick AlN and 40 nm thick Au thin films, respectively.

  14. Vibration and buckling of orthotropic functionally graded micro-plates on the basis of a re-modified couple stress theory

    Directory of Open Access Journals (Sweden)

    Zihao Yang

    Full Text Available A microstructure-dependent model for the free vibration and buckling analysis of an orthotropic functionally graded micro-plate was proposed on the basis of a re-modified couple stress theory. The macro- and microscopic anisotropy were simultaneously taken into account by introducing two material length scale parameters. The material attributes were assumed to vary continuously through the thickness direction by a power law. The governing equations and corresponding boundary conditions were derived through Hamilton’s principle. The Navier method was used to calculate the natural frequencies and buckling loads of a simply supported micro-plate. The numerical results indicated that the present model predicts higher natural frequencies and critical buckling loads than the classical model, particular when the geometric size of the micro-plates is comparable to the material length scale parameters, i.e., the scale effect is well represented. The scale effect becomes more noticeable as the material length scale parameters increase, the anisotropy weaken or the power law index increases, and vice versa. Keywords: Free vibration, Buckling, Functionally graded materials, Modified couple stress theory, Scale effect

  15. Effects of vibration therapy on hormone response and stress in severely disabled patients: a double-blind randomized placebo-controlled clinical trial.

    Science.gov (United States)

    Seco, J; Rodríguez-Pérez, V; López-Rodríguez, A F; Torres-Unda, J; Echevarria, E; Díez-Alegre, M I; Ortega, A; Morán, P; Mendoza-Laíz, N; Abecia Inchaurregui, L C

    2015-01-01

    To assess the effects of vibration therapy (VT) on quality of life and hormone response in severely disabled patients compared with placebo. A longitudinal prospective, double-blind, randomized placebo-controlled trial, with pre and postintervention assessments. A total of 20 severely disabled individuals were recruited from a National Reference Centre in Spain: 13 (65%) men and 7 (35%) women, 45.5 ± 9.32 years of age (range 41: 22-63). We evaluated their physical stress and state anxiety. No statistically significant changes were found in the socio-psychological variables studied, while in the experimental group state anxiety decreased significantly with p < 0.01 (Z = 2.38; one-tailed p = .009) and, among the biological variables, the level of cortisol fell (p = 0.03). Short periods of exposure to low-frequency and low-amplitude local vibration are a safe and effective mechanical stimulus that can have a positive effect in terms of hormone response. VT can be considered to have an anti-stress effect. © 2013 Association of Rehabilitation Nurses.

  16. Cerebrolysin protects against rotenone-induced oxidative stress and neurodegeneration

    Directory of Open Access Journals (Sweden)

    Abdel-Salam OME

    2014-05-01

    Full Text Available Omar ME Abdel-Salam,1 Nadia A Mohammed,2 Eman R Youness,2 Yasser A Khadrawy,3 Enayat A Omara,4 Amany A Sleem51Department of Toxicology and Narcotics, 2Department of Medical Biochemistry, 3Department of Physiology, 4Department of Pathology, 5Department of Pharmacology, National Research Centre, Dokki, Cairo, EgyptAbstract: We investigated the effect of cerebrolysin, a peptide mixture used for promoting memory and recovery from cerebral stroke, on the development of oxidative stress and nigrostriatal cell injury induced by rotenone administration in rats. Rotenone 1.5 mg/kg was given subcutaneously three times weekly either alone or in combination with cerebrolysin at 21.5, 43, or 86 mg/kg. Rats were euthanized 14 days after starting the rotenone injection. Lipid peroxidation (malondialdehyde, reduced glutathione (GSH, nitric oxide (nitrite concentrations, paraoxonase 1 (PON1, and acetylcholinesterase (AChE activities – as well as the monocyte chemoattractant protein-1 (MCP-1 and the antiapoptotic protein Bcl-2 – were measured in the brain. Histopathology, tyrosine hydroxylase, inducible nitric oxide synthase (iNOS, tumor necrosis factor-α (TNF-α, and cleaved caspase-3 immunohistochemistry were also performed. Rotenone caused a significantly elevated oxidative stress and proinflammatory response in the different brain regions. Malondialdehyde and nitric oxide concentrations were significantly increased, while GSH markedly decreased in the cerebral cortex, striatum, hippocampus, and in the rest of the brain. PON1 and AChE activities significantly decreased with respect to the control levels after rotenone application. Striatal Bcl-2 was significantly decreased while MCP-1 increased following rotenone injection. Rotenone caused prominent iNOS, TNF-α, and caspase-3 immunostaining in the striatum and resulted in markedly decreased tyrosine hydroxylase immunoreactivity in the substantia nigra and striatum. Cerebrolysin coadministered with

  17. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  18. Stress-induced variation in evolution: from behavioural plasticity to genetic assimilation

    Science.gov (United States)

    Badyaev, Alexander V

    2005-01-01

    Extreme environments are closely associated with phenotypic evolution, yet the mechanisms behind this relationship are poorly understood. Several themes and approaches in recent studies significantly further our understanding of the importance that stress-induced variation plays in evolution. First, stressful environments modify (and often reduce) the integration of neuroendocrinological, morphological and behavioural regulatory systems. Second, such reduced integration and subsequent accommodation of stress-induced variation by developmental systems enables organismal ‘memory’ of a stressful event as well as phenotypic and genetic assimilation of the response to a stressor. Third, in complex functional systems, a stress-induced increase in phenotypic and genetic variance is often directional, channelled by existing ontogenetic pathways. This accounts for similarity among individuals in stress-induced changes and thus significantly facilitates the rate of adaptive evolution. Fourth, accumulation of phenotypically neutral genetic variation might be a common property of locally adapted and complex organismal systems, and extreme environments facilitate the phenotypic expression of this variance. Finally, stress-induced effects and stress-resistance strategies often persist for several generations through maternal, ecological and cultural inheritance. These transgenerational effects, along with both the complexity of developmental systems and stressor recurrence, might facilitate genetic assimilation of stress-induced effects. Accumulation of phenotypically neutral genetic variance by developmental systems and phenotypic accommodation of stress-induced effects, together with the inheritance of stress-induced modifications, ensure the evolutionary persistence of stress–response strategies and provide a link between individual adaptability and evolutionary adaptation. PMID:16024341

  19. Fluoride induced endoplasmic reticulum stress and calcium overload in ameloblasts.

    Science.gov (United States)

    Zhang, Ying; Zhang, KaiQiang; Ma, Lin; Gu, HeFeng; Li, Jian; Lei, Shuang

    2016-09-01

    The aim of the study was to evaluate the involvement of endoplasmic reticulum stress and intracellular calcium overload on the development of dental fluorosis. We cultured and exposed rat ameloblast HAT-7 cells to various concentrations of fluoride and measured apoptosis with flow cytometry and intracellular Ca2+ changes using confocal microscopy, investigated the protein levels of GRP78, calreticulin, XBP1 and CHOP by western blotting, and their transcriptional levels with RT-PCR. We also created an in vivo model of dental fluorosis by exposing animals to various concentrations of fluoride. Subsequently, thin dental tissue slices were analyzed with H&E staining, immunohistochemical staining, and transmission electron microscopy, TUNEL assay was also performed on dental tissue slices for assessment of apoptosis. High fluoride concentration was associated with decreased ameloblast proliferation, elevated ameloblast apoptosis, and increased intracellular Ca2+ in vitro. The translation and transcription of the proteins associated with endoplasmic reticulum stress were significantly elevated with high concentrations of fluoride. Based on immunohistochemical staining, these proteins were also highly expressed in animals exposed to high fluoride concentrations. Histologically, we found significant fluorosis-like changes in tissues from animals exposed to high fluoride concentrations. Transmission electron microscopy cytology indicated significant apoptotic changes in tissues exposed to high concentrations of fluoride. These results indicate that exposure to high levels of fluoride led to endoplasmic reticulum stress which induced apoptosis in cultured ameloblasts and in vivo rat model, suggesting an important role of calcium overload and endoplasmic reticulum stress triggered by high concentrations of fluoride in the development of dental fluorosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Increased stress-induced inflammatory responses in male patients with major depression and increased early life stress.

    Science.gov (United States)

    Pace, Thaddeus W W; Mletzko, Tanja C; Alagbe, Oyetunde; Musselman, Dominique L; Nemeroff, Charles B; Miller, Andrew H; Heim, Christine M

    2006-09-01

    The authors sought to determine innate immune system activation following psychosocial stress in patients with major depression and increased early life stress. Plasma interleukin (IL)-6, lymphocyte subsets, and DNA binding of nuclear factor (NF)-kB in peripheral blood mononuclear cells were compared in medically healthy male subjects with current major depression and increased early life stress (N=14) versus nondepressed male comparison subjects (N=14) before and after completion of the Trier Social Stress Test. Trier Social Stress Test-induced increases in IL-6 and NF-kappaB DNA-binding were greater in major depression patients with increased early life stress and independently correlated with depression severity, but not early life stress. Natural killer (NK) cell percentages also increased following stress. However, there were no differences between groups and no correlation between NK cell percentage and stress-induced NF-kappaB DNA-binding or IL-6. Male major depression patients with increased early life stress exhibit enhanced inflammatory responsiveness to psychosocial stress, providing preliminary indication of a link between major depression, early life stress and adverse health outcomes in diseases associated with inflammation.

  1. Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice.

    Science.gov (United States)

    Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

    2015-01-01

    Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia.

  2. Catalase activity as a biomarker for mild-stress-induced robustness in Bacillus weihenstephanensis

    NARCIS (Netherlands)

    Besten, den H.M.W.; Effraimidou, S.; Abee, T.

    2013-01-01

    Microorganisms are able to survive and grow in changing environments by activating stress adaptation mechanisms which may enhance bacterial robustness. Stress-induced enhanced robustness complicates the predictability of microbial inactivation. Using psychrotolerant Bacillus weihenstephanensis

  3. Live-cell Imaging Approaches for the Investigation of Xenobiotic-Induced Oxidant Stress

    Science.gov (United States)

    BACKGROUND: Oxidant stress is arguably a universal feature in toxicology. Research studies on the role of oxidant stress induced by xenobiotic exposures have typically relied on the identification of damaged biomolecules using a variety of conventional biochemical and molecular t...

  4. Stress-induced allodynia--evidence of increased pain sensitivity in healthy humans and patients with chronic pain after experimentally induced psychosocial stress.

    Directory of Open Access Journals (Sweden)

    Benjamin Crettaz

    Full Text Available BACKGROUND: Experimental stress has been shown to have analgesic as well as allodynic effect in animals. Despite the obvious negative influence of stress in clinical pain conditions, stress-induced alteration of pain sensitivity has not been tested in humans so far. Therefore, we tested changes of pain sensitivity using an experimental stressor in ten female healthy subjects and 13 female patients with fibromyalgia. METHODS: Multiple sensory aspects of pain were evaluated in all participants with the help of the quantitative sensory testing protocol before (60 min and after (10 and 90 min inducing psychological stress with a standardized psychosocial stress test ("Trier Social Stress Test". RESULTS: Both healthy subjects and patients with fibromyalgia showed stress-induced enhancement of pain sensitivity in response to thermal stimuli. However, only patients showed increased sensitivity in response to pressure pain. CONCLUSIONS: Our results provide evidence for stress-induced allodynia/hyperalgesia in humans for the first time and suggest differential underlying mechanisms determining response to stressors in healthy subjects and patients suffering from chronic pain. Possible mechanisms of the interplay of stress and mediating factors (e.g. cytokines, cortisol on pain sensitivity are mentioned. Future studies should help understand better how stress impacts on chronic pain conditions.

  5. Whole-body Vibration at Thoracic Resonance Induces Sustained Pain and Widespread Cervical Neuroinflammation in the Rat.

    Science.gov (United States)

    Zeeman, Martha E; Kartha, Sonia; Jaumard, Nicolas V; Baig, Hassam A; Stablow, Alec M; Lee, Jasmine; Guarino, Benjamin B; Winkelstein, Beth A

    2015-09-01

    Whole-body vibration (WBV) is associated with back and neck pain in military personnel and civilians. However, the role of vibration frequency and the physiological mechanisms involved in pain symptoms are unknown. This study asked the following questions: (1) What is the resonance frequency of the rat spine for WBV along the spinal axis, and how does frequency of WBV alter the extent of spinal compression/extension? (2) Does a single WBV exposure at resonance induce pain that is sustained? (3) Does WBV at resonance alter the protein kinase C epsilon (PKCε) response in the dorsal root ganglia (DRG)? (4) Does WBV at resonance alter expression of calcitonin gene-related peptide (CGRP) in the spinal dorsal horn? (5) Does WBV at resonance alter the spinal neuroimmune responses that regulate pain? Resonance of the rat (410 ± 34 g, n = 9) was measured by imposing WBV at frequencies from 3 to 15 Hz. Separate groups (317 ± 20 g, n = 10/treatment) underwent WBV at resonance (8 Hz) or at a nonresonant frequency (15 Hz). Behavioral sensitivity was assessed throughout to measure pain, and PKCε in the DRG was quantified as well as spinal CGRP, glial activation, and cytokine levels at Day 14. Accelerometer-based thoracic transmissibility peaks at 8 Hz (1.86 ± 0.19) and 9 Hz (1.95 ± 0.19, mean difference [MD] 0.290 ± 0.266, p resonant frequency (8 Hz) compared with 15 Hz WBV. PKCε in the nociceptors of the DRG increases according to the severity of WBV with greatest increases after 8 Hz WBV (p resonance. WBV at resonance produces long-lasting pain and widespread activation of a host of nociceptive and neuroimmune responses as compared with WBV at a nonresonance condition. Based on this work, future investigations into the temporal and regional neuroimmune response to resonant WBV in both genders would be useful. Although WBV is a major issue affecting the military population, there is little insight about its mechanisms of injury and pain. The neuroimmune responses

  6. An advanced tube wear and fatigue workstation to predict flow induced vibrations of steam generator tubes; Un outil de prediction de l`usure et de la fatigue des tubes de generateurs de vapeur soumis a des vibrations sous ecoulement

    Energy Technology Data Exchange (ETDEWEB)

    Gay, N. [Electricite de France (EDF), 78 - Chatou (France); Baratte, C. [Electricite de France (EDF), 69 - Villeurbanne (France); Flesch, B. [Electricite de France (EDF), 75 - Paris (France)

    1997-12-31

    Flow induced tube vibration damage is a major concern for designers and operators of nuclear power plant steam generators (SG). The operating flow-induced vibrational behaviour has to be estimated accurately to allow a precise evaluation of the new safety margins in order to optimize the maintenance policy. For this purpose, an industrial `Tube Wear and Fatigue Workstation`, called `GEVIBUS Workstation` and based on an advanced methodology for predictive analysis of flow-induced vibration of tube bundles subject to cross-flow has been developed at Electricite de France. The GEVIBUS Workstation is an interactive processor linking modules as: thermalhydraulic computation, parametric finite element builder, interface between finite element model, thermalhydraulic code and vibratory response computations, refining modelling of fluid-elastic and random forces, linear and non-linear dynamic response and the coupled fluid-structure system, evaluation of tube damage due to fatigue and wear, graphical outputs. Two practical applications are also presented in the paper; the first simulation refers to an experimental set-up consisting of a straight tube bundle subject to water cross-flow, while the second one deals with an industrial configuration which has been observed in some operating steam generators i.e., top tube support plate degradation. In the first case the GEVIBUS predictions in terms of tube displacement time histories and phase planes have been found in very good agreement with experiment. In the second application the GEVIBUS computation showed that a tube with localized degradation is much more stable than a tube located in an extended degradation zone. Important conclusions are also drawn concerning maintenance. (author). 28 refs.

  7. Extinction-induced neuroplasticity attenuates stress-induced cocaine seeking: a state-dependent learning hypothesis.

    Science.gov (United States)

    Self, David W; Choi, Kwang-Ho

    2004-09-01

    Chronic drug use weakens excitatory neocortical input to the nucleus accumbens (NAc). We previously reported that extinction training, a form of inhibitory learning that progressively reduces cocaine-seeking behaviour when reward is withheld, reverses this deficit by up-regulating GluR1 and GluR2/3 subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) glutamate receptors in the NAc. The level of GluR1 up-regulation is positively associated with a reduction in cocaine seeking, suggesting that extinction-induced up-regulation in AMPA receptors in the NAc opposes motivational influences that maintain cocaine seeking. This hypothesis is supported by the finding that over-expression of GluR1 and GluR2 in the NAc facilitates extinction of cocaine self-administration. Furthermore, a single extinction training session conducted during GluR1 and GluR2 over-expression strongly and selectively attenuates the ability of an environmental stressor to trigger relapse to cocaine seeking long after GluR1 and GluR2 over-expression declines. These results could suggest that excitatory input to the NAc promotes extinction learning, but only when memory is recalled under stressful situations. Recent studies indicate that both environmental stress and the frustrative stress of withholding reward during extinction of drug self-administration induce similar neurochemical events in the NAc. These neurochemical events could impose a "state-dependency" on extinction learning such that subsequent exposure to stress acts as a cue to enhance retrieval of extinction memory. Our results suggest that extinction-induced up-regulation in NAc AMPA receptors acts reciprocally to facilitate state-dependent extinction learning, as stressful situations evoke extinction memories that exert powerful inhibitory control over drug-seeking behaviour. These results may have important therapeutic implications for behaviour-based approaches aimed at treating drug addiction.

  8. Azadirachta indica attenuates cisplatin-induced nephrotoxicity and oxidative stress.

    Science.gov (United States)

    Abdel Moneim, Ahmed E; Othman, Mohamed S; Aref, Ahmed M

    2014-01-01

    We investigated the effects of methanolic leaves extract of Azadirachta indica (MLEN, 500 mg/kg bwt) on cisplatin- (CP-) induced nephrotoxicity and oxidative stress in rats. CP (5 mg/kg bwt) was injected intraperitoneally and MLEN was given by gastric gavage for 5 days before or after CP injection. After 5 days of CP injection, CP-induced injury of the renal tissue was evidenced (i) as histopathological damage of the renal tissue, (ii) as increases in serum uric acid, urea, and creatinine, (iii) as increases in malondialdehyde (MDA) and nitric oxide (NO), (iv) as decreases in the level of glutathione and activities of superoxide dismutase, catalase, glutathione reductase, glutathione-S-transferase, and glutathione peroxidase, and (v) as increase in the expression of nuclear factor kappa B and apoptosis in kidney tissues. However, the oral administration of MLEN to CP-intoxicated rats for 5 days brought back MDA, NO production, and enzymatic and nonenzymatic antioxidants to near normalcy. Moreover, the histological observations evidenced that neem extract effectively rescues the kidney from CP-mediated oxidative damage. Furthermore, PCR results for caspase-3 and caspase-9 and Bax genes showed downregulation in MLEN treated groups. Therefore, Azadirachta indica can be considered a potential candidate for protection of nephrotoxicity induced by cisplatin.

  9. Azadirachta indica Attenuates Cisplatin-Induced Nephrotoxicity and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Ahmed E. Abdel Moneim

    2014-01-01

    Full Text Available We investigated the effects of methanolic leaves extract of Azadirachta indica (MLEN, 500 mg/kg bwt on cisplatin- (CP- induced nephrotoxicity and oxidative stress in rats. CP (5 mg/kg bwt was injected intraperitoneally and MLEN was given by gastric gavage for 5 days before or after CP injection. After 5 days of CP injection, CP-induced injury of the renal tissue was evidenced (i as histopathological damage of the renal tissue, (ii as increases in serum uric acid, urea, and creatinine, (iii as increases in malondialdehyde (MDA and nitric oxide (NO, (iv as decreases in the level of glutathione and activities of superoxide dismutase, catalase, glutathione reductase, glutathione-S-transferase, and glutathione peroxidase, and (v as increase in the expression of nuclear factor kappa B and apoptosis in kidney tissues. However, the oral administration of MLEN to CP-intoxicated rats for 5 days brought back MDA, NO production, and enzymatic and nonenzymatic antioxidants to near normalcy. Moreover, the histological observations evidenced that neem extract effectively rescues the kidney from CP-mediated oxidative damage. Furthermore, PCR results for caspase-3 and caspase-9 and Bax genes showed downregulation in MLEN treated groups. Therefore, Azadirachta indica can be considered a potential candidate for protection of nephrotoxicity induced by cisplatin.

  10. Calorie-induced ER stress suppresses uroguanylin satiety signaling in diet-induced obesity.

    Science.gov (United States)

    Kim, G W; Lin, J E; Snook, A E; Aing, A S; Merlino, D J; Li, P; Waldman, S A

    2016-05-23

    The uroguanylin-GUCY2C gut-brain axis has emerged as one component regulating feeding, energy homeostasis, body mass and metabolism. Here, we explore a role for this axis in mechanisms underlying diet-induced obesity (DIO). Intestinal uroguanylin expression and secretion, and hypothalamic GUCY2C expression and anorexigenic signaling, were quantified in mice on high-calorie diets for 14 weeks. The role of endoplasmic reticulum (ER) stress in suppressing uroguanylin in DIO was explored using tunicamycin, an inducer of ER stress, and tauroursodeoxycholic acid (TUDCA), a chemical chaperone that inhibits ER stress. The impact of consumed calories on uroguanylin expression was explored by dietary manipulation. The role of uroguanylin in mechanisms underlying obesity was examined using Camk2a-Cre-ER(T2)-Rosa-STOP(loxP/loxP)-Guca2b mice in which tamoxifen induces transgenic hormone expression in brain. DIO suppressed intestinal uroguanylin expression and eliminated its postprandial secretion into the circulation. DIO suppressed uroguanylin through ER stress, an effect mimicked by tunicamycin and blocked by TUDCA. Hormone suppression by DIO reflected consumed calories, rather than the pathophysiological milieu of obesity, as a diet high in calories from carbohydrates suppressed uroguanylin in lean mice, whereas calorie restriction restored uroguanylin in obese mice. However, hypothalamic GUCY2C, enriched in the arcuate nucleus, produced anorexigenic signals mediating satiety upon exogenous agonist administration, and DIO did not impair these responses. Uroguanylin replacement by transgenic expression in brain repaired the hormone insufficiency and reconstituted satiety responses opposing DIO and its associated comorbidities, including visceral adiposity, glucose intolerance and hepatic steatosis. These studies reveal a novel pathophysiological mechanism contributing to obesity in which calorie-induced suppression of intestinal uroguanylin impairs hypothalamic mechanisms

  11. Vibration Response Characteristics of the Cross Tunnel Structure

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2016-01-01

    Full Text Available It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

  12. Protective Effects of Carvacrol against Oxidative Stress Induced by Chronic Stress in Rat’s Brain, Liver, and Kidney

    Directory of Open Access Journals (Sweden)

    Saeed Samarghandian

    2016-01-01

    Full Text Available Restraint stress may be associated with elevated free radicals, and thus, chronic exposure to oxidative stress may cause tissue damage. Several studies have reported that carvacrol (CAR has a protective effect against oxidative stress. The present study was designed to investigate the protective effects of CAR on restraint stress induced oxidative stress damage in the brain, liver, and kidney. For chronic restraint stress, rats were kept in the restrainers for 6 h every day, for 21 consecutive days. The animals received systemic administrations of CAR daily for 21 days. To evaluate the changes of the oxidative stress parameters following restraint stress, the levels of malondialdehyde (MDA, reduced glutathione (GSH, superoxide dismutase (SOD, glutathione peroxidase (GPx, glutathione reductase (GR, and catalase (CAT activities were measured in the brain, liver, and kidney. In the stressed animals that received vehicle, the MDA level was significantly higher (P<0.001 and the levels of GSH and antioxidant enzymes were significantly lower than the nonstressed animals (P<0.001. CAR ameliorated the changes in the stressed animals as compared with the control group (P<0.001. This study indicates that CAR can prevent restraint stress induced oxidative damage.

  13. Performance Analysis of Wind-Induced Piezoelectric Vibration Bimorph Cantilever for Rotating Machinery

    OpenAIRE

    Gongbo Zhou; Houlian Wang; Zhencai Zhu; Linghua Huang; Wei Li

    2015-01-01

    Harvesting the energy contained in the running environment of rotating machinery would be a good way to supplement energy to the wireless sensor. In this paper, we take piezoelectric bimorph cantilever beam with parallel connection mode as energy collector and analyze the factors which can influence the generation performance. First, a modal response theory model is built. Second, the static analysis, modal analysis, and piezoelectric harmonic response analysis of the wind-induced piezoelectr...

  14. Exercise-induced oxidative stress: A tool for “hormesis” and “adaptive response”

    National Research Council Canada - National Science Library

    Koyama, Katsuhiro

    2014-01-01

    ... adaptation to physical exercise. It is becoming increasingly clear that exercise-related beneficial adaptations are strongly regulated by exercise-induced oxidative stress, consistent with hormesis theory...

  15. Performance Analysis of Wind-Induced Piezoelectric Vibration Bimorph Cantilever for Rotating Machinery

    Directory of Open Access Journals (Sweden)

    Gongbo Zhou

    2015-01-01

    Full Text Available Harvesting the energy contained in the running environment of rotating machinery would be a good way to supplement energy to the wireless sensor. In this paper, we take piezoelectric bimorph cantilever beam with parallel connection mode as energy collector and analyze the factors which can influence the generation performance. First, a modal response theory model is built. Second, the static analysis, modal analysis, and piezoelectric harmonic response analysis of the wind-induced piezoelectric bimorph cantilever beam are given in detail. Finally, an experiment is also conducted. The results show that wind-induced piezoelectric bimorph cantilever beam has low resonant frequency and stable output under the first modal mode and can achieve the maximum output voltage under the resonant condition. The output voltage increases with the increase of the length and width of wind-induced piezoelectric bimorph cantilever beam, but the latter increasing amplitude is relatively smaller. In addition, the output voltage decreases with the increase of the thickness and the ratio of metal substrate to piezoelectric patches thickness. The experiment showed that the voltage amplitude generated by the piezoelectric bimorph cantilever beam can reach the value simulated in ANSYS, which is suitable for actual working conditions.

  16. Maternal chewing during prenatal stress ameliorates stress-induced hypomyelination, synaptic alterations, and learning impairment in mouse offspring.

    Science.gov (United States)

    Suzuki, Ayumi; Iinuma, Mitsuo; Hayashi, Sakurako; Sato, Yuichi; Azuma, Kagaku; Kubo, Kin-Ya

    2016-11-15

    Maternal chewing during prenatal stress attenuates both the development of stress-induced learning deficits and decreased cell proliferation in mouse hippocampal dentate gyrus. Hippocampal myelination affects spatial memory and the synaptic structure is a key mediator of neuronal communication. We investigated whether maternal chewing during prenatal stress ameliorates stress-induced alterations of hippocampal myelin and synapses, and impaired development of spatial memory in adult offspring. Pregnant mice were divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube, and was initiated on day 12 of pregnancy and continued until delivery. Mice in the stress/chewing group were given a wooden stick to chew during restraint. In 1-month-old pups, spatial memory was assessed in the Morris water maze, and hippocampal oligodendrocytes and synapses in CA1 were assayed by immunohistochemistry and electron microscopy. Prenatal stress led to impaired learning ability, and decreased immunoreactivity of myelin basic protein (MBP) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in the hippocampal CA1 in adult offspring. Numerous myelin sheath abnormalities were observed. The G-ratio [axonal diameter to axonal fiber diameter (axon plus myelin sheath)] was increased and postsynaptic density length was decreased in the hippocampal CA1 region. Maternal chewing during stress attenuated the prenatal stress-induced impairment of spatial memory, and the decreased MBP and CNPase immunoreactivity, increased G-ratios, and decreased postsynaptic-density length in the hippocampal CA1 region. These findings suggest that chewing during prenatal stress in dams could be an effective coping strategy to prevent hippocampal behavioral and morphologic impairments in their offspring. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Dezocine for anesthesia and stress reduction in induced abortion

    Directory of Open Access Journals (Sweden)

    Zheng M

    2015-03-01

    Full Text Available Mengliang Zheng, Yanru Guo, Shiqiang Shan, Sen Yang Department of Anesthesiology, Cangzhou Central Hospital, Hebei, People’s Republic of China Background: The purpose of this study was to evaluate the efficacy of dezocine with regard to analgesic and stress reduction outcomes in women undergoing induced abortion.Methods: A total of 126 women in early pregnancy (up to 14 weeks’ gestation who underwent induced abortion at Cangzhou Central Hospital from May 2012 to May 2013 were randomly assigned to a control (propofol group (n=63 or an intervention (propofol + dezocine group (n=63. Wake-up time, orientation force recovery time, incidence of adverse reactions, postoperative visual analog scale (VAS score, analgesic effect, and respiratory and circulatory monitoring before the operation, 5 minutes into the operation, and 5 minutes after the operation were compared between the two groups.Results: The surgical procedure and anesthesia were performed successfully in all patients. Systolic and diastolic blood pressure and oxyhemoglobin saturation in the intervention group were significantly higher than in the control group; however, heart rate was significantly lower in the intervention group than in the control group 5 minutes into the operation (all P<0.05. There were no statistically significant differences in these parameters before surgery and after recovery. The postoperative VAS score (2.82±0.72, Ramsay score (2.65±0.65, and anesthetic effect in the intervention group were better than in the control group (3.90±0.84 and 2.21±0.49, respectively, and all differences were statistically significant (P<0.05. The wake-up time (3.41±0.79 minutes and orientation force recovery time (4.28±0.92 minutes were all significantly shorter (P<0.05 in the intervention group than in the control group, as was the incidence of adverse reactions (7.94% versus 26.98%, respectively.Conclusion: Adverse reactions of propofol combined with dezocine in painless

  18. Laser-induced stress transients: applications for molecular delivery

    Science.gov (United States)

    Flotte, Thomas J.; Lee, Shun; Zhang, Hong; McAuliffe, Daniel J.; Douki, Tina; Doukas, Apostolos G.

    1995-05-01

    Lasers can be used to enhance the delivery of a number of molecules. Other investigators have demonstrated local release of molecules from liposomes following laser irradiation, microbeam disruption of the cell membrane to increase cell transport, microbeam ablation of the zona pellucida surrounding the ovum to increase the chances of fertilization, and increased transcutaneous transport following ablation of the stratum corneum. Our experiments have shown that laser-induced stress transients can be utilized as a vector for intracellular delivery of molecules that may or may not normally cross the cell membrane. These two conditions have been tested with Photofrin and DNA. This technology may have applications in cell and molecular biology, cancer therapy, gene therapy, and others.

  19. Method for analyzing electromagnetic-force-induced vibration and noise analysis; Denjiryoku reiki ni yoru dendoki no shindo hoshaon kaisekiho

    Energy Technology Data Exchange (ETDEWEB)

    Shiohata, K.; Nemoto, K.; Nagawa, Y.; Sakamoto, S.; Kobayashi, T.; Ito, M.; Koharagi, H. [Hitachi, Ltd, Tokyo (Japan)

    1998-11-01

    In this analysis method, electromagnetic force calculated by 2-dimensional analysis is transformed into external force for 3-dimensional structural-vibration analysis. And a modeling procedure for a vibrating structure is developed. Further, a space-modal-resonance criteria which relates electromagnetic force to structural-vibration or noise is introduced. In the structural-vibration analysis, the finite element method is used; and in the noise analysis, the boundary element method is used. Finally, vibration and noise of an induction motor are calculated using this criteria. Consequently, high-accuracy modeling is achieved and noise the calculated by the simulation almost coincides with that obtained by experiments. And it is clarified that the-space-modal resonance criteria is effective in numerical simulation. 11 refs., 9 figs., 3 tabs.

  20. Mathematical quantification of the induced stress resistance of microbial populations during non-isothermal stresses.

    Science.gov (United States)

    Garre, Alberto; Huertas, Juan Pablo; González-Tejedor, Gerardo A; Fernández, Pablo S; Egea, Jose A; Palop, Alfredo; Esnoz, Arturo

    2018-02-02

    This contribution presents a mathematical model to describe non-isothermal microbial inactivation processes taking into account the acclimation of the microbial cell to thermal stress. The model extends the log-linear inactivation model including a variable and model parameters quantifying the induced thermal resistance. The model has been tested on cells of Escherichia coli against two families of non-isothermal profiles with different constant heating rates. One of the families was composed of monophasic profiles, consisting of a non-isothermal heating stage from 35 to 70°C; the other family was composed of biphasic profiles, consisting of a non-isothermal heating stage followed by a holding period at constant temperature of 57.5°C. Lower heating rates resulted in a higher thermal resistance of the bacterial population. This was reflected in a higher D-value. The parameter estimation was performed in two steps. Firstly, the D and z-values were estimated from the isothermal experiments. Next, the parameters describing the acclimation were estimated using one of the biphasic profiles. This set of parameters was able to describe the remaining experimental data. Finally, a methodology for the construction of diagrams illustrating the magnitude of the induced thermal resistance is presented. The methodology has been illustrated by building it for a biphasic temperature profile with a linear heating phase and a holding phase. This diagram provides a visualization of how the shape of the temperature profile (heating rate and holding temperature) affects the acclimation of the cell to the thermal stress. This diagram can be used for the design of inactivation treatments by industry taking into account the acclimation of the cell to the thermal stress. Copyright © 2017 Elsevier B.V. All rights reserved.