WorldWideScience

Sample records for large strain induced

  1. Numerical modeling of large field-induced strains in ferroelastic bodies: a continuum approach

    International Nuclear Information System (INIS)

    Raikher, Yu L; Stolbov, O V

    2008-01-01

    A consistent continuum model of a soft magnetic elastomer (SME) is presented and developed for the case of finite strain. The numeric algorithm enabling one to find the field-induced shape changes of an SME body is described. The reliability of the method is illustrated by several examples revealing specifics of the magnetostriction effect in SME samples of various geometries

  2. A probiotic strain of L. acidophilus reduces DMH-induced large intestinal tumors in male Sprague-Dawley rats.

    Science.gov (United States)

    McIntosh, G H; Royle, P J; Playne, M J

    1999-01-01

    Probiotic bacteria strains were examined for their influence on 1,2-dimethylhydrazine (DMH)-induced intestinal tumors in 100 male Sprague-Dawley rats. Lactobacillus acidophilus (Delvo Pro LA-1), Lactobacillus rhamnosus (GG), Bifidobacterium animalis (CSCC1941), and Streptococcus thermophilus (DD145) strains were examined for their influence when added as freeze-dried bacteria to an experimental diet based on a high-fat semipurified (AIN-93) rodent diet. Four bacterial treatments were compared: L. acidophilus, L. acidophilus + B. animalis, L. rhamnosus, and S. thermophilus, the bacteria being added daily at 1% freeze-dried weight (10(10) colony-forming units/g) to the diet. Trends were observed in the incidence of rats with large intestinal tumors for three treatments: 25% lower than control for L. acidophilus, 20% lower for L. acidophilus + B. animalis and L. rhamnosus treatments, and 10% lower for S. thermophilus. Large intestinal tumor burden was significantly lower for treated rats with L. acidophilus than for the control group (10 and 3 tumors/treatment group, respectively, p = 0.05). Large intestinal tumor mass index was also lower for the L. acidophilus treatment than for control (1.70 and 0.10, respectively, p L. acidophilus, no adenocarcinomas were present in the colons. Pulsed-field gel electrophoresis of bacterial chromosomal DNA fragments was used to differentiate introduced (exogenous) bacterial strains from indigenous bacteria of the same genera present in the feces. Survival during gut passage and displacement of indigenous lactobacilli occurred with introduced L. acidophilus and L. rhamnosus GG during the probiotic treatment period. However, introduced strains of B. animalis and S. thermophilus were not able to be isolated from feces. It is concluded that this strain of L. acidophilus supplied as freeze-dried bacteria in the diet was protective, as seen by a small but significant inhibition of tumors within the rat colon.

  3. Large bandgap blueshifts in the InGaP/InAlGaP laser structure using novel strain-induced quantum well intermixing

    KAUST Repository

    Al-Jabr, Ahmad

    2016-04-04

    We report on a novel quantum well intermixing (QWI) technique that induces a large degree of bandgapblueshift in the InGaP/InAlGaP laser structure. In this technique, high external compressive strain induced by a thick layer of SiO2 cap with a thickness ≥1 μm was used to enhance QWI in the tensile-strained InGaP/InAlGaP quantum well layer. A bandgapblueshift as large as 200 meV was observed in samples capped with 1-μm SiO2 and annealed at 1000 °C for 120 s. To further enhance the degree of QWI, cycles of annealing steps were applied to the SiO2 cap. Using this method, wavelength tunability over the range of 640 nm to 565 nm (∼250 meV) was demonstrated. Light-emitting diodes emitting at red (628 nm), orange (602 nm), and yellow (585 nm) wavelengths were successfully fabricated on the intermixed samples. Our results show that this new QWI method technique may pave the way for the realization of high-efficiency orange and yellow light-emitting devices based on the InGaP/InAlGaP material system.

  4. Large bandgap blueshifts in the InGaP/InAlGaP laser structure using novel strain-induced quantum well intermixing

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jabr, A. A.; Majid, M. A.; Alias, M. S.; Ng, T. K.; Ooi, B. S., E-mail: boon.ooi@kaust.edu.sa [Photonics Laboratory, King Abdullah University of Science & Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia (KSA) (Saudi Arabia); Anjum, D. H. [Advanced Nanofabrication, Imaging and Characterization Core Facilities, (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia (KSA) (Saudi Arabia)

    2016-04-07

    We report on a novel quantum well intermixing (QWI) technique that induces a large degree of bandgap blueshift in the InGaP/InAlGaP laser structure. In this technique, high external compressive strain induced by a thick layer of SiO{sub 2} cap with a thickness ≥1 μm was used to enhance QWI in the tensile-strained InGaP/InAlGaP quantum well layer. A bandgap blueshift as large as 200 meV was observed in samples capped with 1-μm SiO{sub 2} and annealed at 1000 °C for 120 s. To further enhance the degree of QWI, cycles of annealing steps were applied to the SiO{sub 2} cap. Using this method, wavelength tunability over the range of 640 nm to 565 nm (∼250 meV) was demonstrated. Light-emitting diodes emitting at red (628 nm), orange (602 nm), and yellow (585 nm) wavelengths were successfully fabricated on the intermixed samples. Our results show that this new QWI method technique may pave the way for the realization of high-efficiency orange and yellow light-emitting devices based on the InGaP/InAlGaP material system.

  5. Strain Induced Adatom Correlations

    OpenAIRE

    Kappus, Wolfgang

    2012-01-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to sup...

  6. Strain induced adatom correlations

    Science.gov (United States)

    Kappus, Wolfgang

    2012-12-01

    A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from zero to a limit given by stability constraints. W, Nb, Ta and Au surfaces are taken as examples to show the effects of different elastic anisotropy regions. Results of the calculation are shown by appropriate plots and discussed. A mapping to superstructures is tried. Corresponding adatom configurations from Monte Carlo simulations are shown.

  7. Strain induced ferromagnetism and large magnetoresistance of epitaxial La1.5Sr0.5CoMnO6 thin films

    Science.gov (United States)

    Krishna Murthy, J.; Jyotsna, G.; N, Nileena; Anil Kumar, P. S.

    2017-08-01

    In this study, the structural, magnetic, and magneto-transport properties of La1.5Sr0.5CoMnO6 (LSCMO) thin films deposited on a SrTiO3 (001) substrate were investigated. A normal θ/2θ x-ray diffraction, rocking curve, ϕ-scan, and reciprocal space mapping data showed that prepared LSCMO thin films are single phase and highly strained with epitaxial nature. Temperature vs. magnetization of LSCMO films exhibits strain-induced ferromagnetic ordering with TC ˜ 165 K. In contrast to the bulk samples, there was no exchange bias and canted type antiferromagnetic and spin glass behavior in films having thickness (t) ≤ 26 nm. Temperature dependent resistivity data were explained using Schnakenberg's model and the polaron hopping conduction process. The slope change in resistivity and magnetoresistance maximum (˜65%) around TC indicates the existence of a weak double exchange mechanism between the mixed valence states of transition metal ions. Suppression of spin dependent scattering with the magnetic field is attributed for the large negative magnetoresistance in LSCMO films.

  8. Electronic properties of polycrystalline graphene under large local strain

    International Nuclear Information System (INIS)

    He, Xin; Tang, Ning; Duan, Junxi; Mei, Fuhong; Meng, Hu; Lu, Fangchao; Xu, Fujun; Yang, Xuelin; Gao, Li; Wang, Xinqiang; Shen, Bo; Ge, Weikun

    2014-01-01

    To explore the transport properties of polycrystalline graphene under large tensile strain, a strain device has been fabricated using piezocrystal to load local strain onto graphene, up to 22.5%. Ionic liquid gate whose capability of tuning carrier density being much higher than that of a solid gate is used to survey the transfer characteristics of the deformed graphene. The conductance of the Dirac point and field effect mobility of electrons and holes is found to decrease with increasing strain, which is attributed to the scattering of the graphene grain boundaries, the strain induced change of band structure, and defects. However, the transport gap is still not opened. Our study is helpful to evaluate the application of graphene in stretchable electronics.

  9. Antibody induced by immunization with the Jeryl Lynn mumps vaccine strain effectively neutralizes a heterologous wild-type mumps virus associated with a large outbreak.

    Science.gov (United States)

    Rubin, Steven A; Qi, Li; Audet, Susette A; Sullivan, Bradley; Carbone, Kathryn M; Bellini, William J; Rota, Paul A; Sirota, Lev; Beeler, Judy

    2008-08-15

    Recent mumps outbreaks in older vaccinated populations were caused primarily by genotype G viruses, which are phylogenetically distinct from the genotype A vaccine strains used in the countries affected by the outbreaks. This finding suggests that genotype A vaccine strains could have reduced efficacy against heterologous mumps viruses. The remote history of vaccination also suggests that waning immunity could have contributed to susceptibility. To examine these issues, we obtained consecutive serum samples from children at different intervals after vaccination and assayed the ability of these samples to neutralize the genotype A Jeryl Lynn mumps virus vaccine strain and a genotype G wild-type virus obtained during the mumps outbreak that occurred in the United States in 2006. Although the geometric mean neutralizing antibody titers against the genotype G virus were approximately one-half the titers measured against the vaccine strain, and although titers to both viruses decreased with time after vaccination, antibody induced by immunization with the Jeryl Lynn mumps vaccine strain effectively neutralized the outbreak-associated virus at all time points tested.

  10. Large strain cyclic behavior of metastable austenic stainless steel

    International Nuclear Information System (INIS)

    Geijselaers, H.J.M.; Hilkhuijsen, P.; Bor, T.C.; Boogaard, A.H. van den

    2015-01-01

    Metastable austenitic stainless steel will transform to martensite when subjected to mechanical working. In this research an austenitic stainless steel has been subjected to large amplitude strain paths containing a strain reversal. During the tests, apart from the stress and the strain also magnetic induction was measured. From the in situ magnetic induction measurements an estimate of the stress partitioning among the phases is determined. When the strain path reversal is applied at low strains, a classical Bauschinger effect is observed. When the strain reversal is applied at higher strains, a higher flow stress is measured after the reversal compared to the flow stress before reversal. Also a stagnation of the transformation is observed, meaning that a higher strain as well as a higher stress than before the strain path change is required to restart the transformation after reversal. The observed behavior can be explained by a model in which for the martensitic transformation a stress induced transformation model is used. The constitutive behavior of both the austenite phase and the martensite is described by a Chaboche model to account for the Bauschinger effect. Mean-field homogenization of the material behavior of the individual phases is employed to obtain a constitutive behavior of the two-phase composite. The overall applied stress, the stress in the martensite phase and the observed transformation behavior during cyclic shear are very well reproduced by the model simulations

  11. Large strain cyclic behavior of metastable austenic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Geijselaers, H.J.M., E-mail: h.j.m.geijselaers@utwente.nl; Hilkhuijsen, P.; Bor, T.C.; Boogaard, A.H. van den

    2015-04-17

    Metastable austenitic stainless steel will transform to martensite when subjected to mechanical working. In this research an austenitic stainless steel has been subjected to large amplitude strain paths containing a strain reversal. During the tests, apart from the stress and the strain also magnetic induction was measured. From the in situ magnetic induction measurements an estimate of the stress partitioning among the phases is determined. When the strain path reversal is applied at low strains, a classical Bauschinger effect is observed. When the strain reversal is applied at higher strains, a higher flow stress is measured after the reversal compared to the flow stress before reversal. Also a stagnation of the transformation is observed, meaning that a higher strain as well as a higher stress than before the strain path change is required to restart the transformation after reversal. The observed behavior can be explained by a model in which for the martensitic transformation a stress induced transformation model is used. The constitutive behavior of both the austenite phase and the martensite is described by a Chaboche model to account for the Bauschinger effect. Mean-field homogenization of the material behavior of the individual phases is employed to obtain a constitutive behavior of the two-phase composite. The overall applied stress, the stress in the martensite phase and the observed transformation behavior during cyclic shear are very well reproduced by the model simulations.

  12. Towards development of nanofibrous large strain flexible strain sensors with programmable shape memory properties

    Science.gov (United States)

    Khalili, N.; Asif, H.; Naguib, H. E.

    2018-05-01

    Electrospun polymeric fibers can be used as strain sensors due to their large surface to weight/volume ratio, high porosity and pore interconnectivity. Large strain flexible strain sensors are used in numerous applications including rehabilitation, health monitoring, and sports performance monitoring where large strain detection should be accommodated by the sensor. This has boosted the demand for a stretchable, flexible and highly sensitive sensor able to detect a wide range of mechanically induced deformations. Herein, a physically cross-linked polylactic acid (PLA) and thermoplastic polyurethane (TPU) blend is made into nanofiber networks via electrospinning. The PLA/TPU weight ratio is optimized to obtain a maximum attainable strain of 100% while maintaining its mechanical integrity. The TPU/PLA fibers also allowed for their thermally activated recovery due to shape memory properties of the substrate. This novel feature enhances the sensor’s performance as it is no longer limited by its plastic deformation. Using spray coating method, a homogeneous layer of single-walled carbon nanotube is deposited onto the as-spun fiber mat to induce electrical conductivity to the surface of the fibers. It is shown that stretching and bending the sensor result in a highly sensitive and linear response with a maximum gauge factor of 33.

  13. Strain-induced large spin splitting and persistent spin helix at LaAlO$_3$/SrTiO$_3$ interface

    OpenAIRE

    Yamaguchi, Naoya; Ishii, Fumiyuki

    2017-01-01

    We investigated the effect of the tensile strain on the spin splitting at the n-type interface in LaAlO$_3$/SrTiO$_3$ in terms of the spin-orbit coupling coefficient $\\alpha$ and spin texture in the momentum space using first-principles calculations. We found that the $\\alpha$ could be controlled by the tensile strain and be enhanced up to 5 times for the tensile strain of 7%, and the effect of the tensile strain leads to a persistent spin helix, which has a long spin lifetime. These results ...

  14. Resonant tunneling measurements of size-induced strain relaxation

    Science.gov (United States)

    Akyuz, Can Deniz

    Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of

  15. Electric Field-Induced Large Strain in Ni/Sb-co Doped (Bi0.5Na0.5) TiO3-Based Lead-Free Ceramics

    Science.gov (United States)

    Li, Liangliang; Hao, Jigong; Xu, Zhijun; Li, Wei; Chu, Ruiqing

    2018-02-01

    Lead-free piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1- x (Ni0.5Sb0.5) x O3 (BNBT6.5- xNS) have been fabricated using conventional solid sintering technique. The effect of (Ni, Sb) doping on the phase structure and electrical properties of BNBT6.5 ceramics were systematically investigated. Results show that the addition of (Ni, Sb) destroyed the ferroelectric long-range order of BNBT6.5 and shifted the ferroelectric-relaxor transition temperature ( T F-R) down to room temperature. Thus, this process induced an ergodic relaxor phase at zero field in samples with x = 0.005. Under the electric field, the ergodic relaxor phase could reversibly transform to ferroelectric phase, which promotes the strain response with peak value of 0.38% (at 80 kV/cm, corresponding to d 33 * = 479 pm/V) at x = 0.005. Temperature-dependent measurements of both polarization and strain confirmed that the large strain originated from a reversible field-induced ergodic relaxor to ferroelectric phase transformation. The proposed material exhibits potential for nonlinear actuators.

  16. Characterizing large strain crush response of redwood

    International Nuclear Information System (INIS)

    Cramer, S.M.; Hermanson, J.C.

    1996-12-01

    Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most rudimentary information exists on its crush properties. The objectives of the study were to fill the information gap by collecting triaxial load-deformation data for redwood; to use these data to characterize redwood crush, assess current wood failure theories, provide developments toward a complete stress-strain theory for redwood; and to review the literature on strain-rate effects on redwood crush performance. The load-deformation responses of redwood at temperature conditions corresponding to ambient (70 degrees F), 150 degrees F, and -20 degrees F conditions were measured in approximately 100 confined compression tests for crush levels leading to material densification. Data analysis provided a more complete description of redwood crush performance and a basis for assessing proposed general orthotropic stress-strain relationships for redwood. A review of existing literature indicated that strain-rate effects cause at most a 20 percent increase in crush stress parallel to grain

  17. Benchmarking multi-dimensional large strain consolidation analyses

    International Nuclear Information System (INIS)

    Priestley, D.; Fredlund, M.D.; Van Zyl, D.

    2010-01-01

    Analyzing the consolidation of tailings slurries and dredged fills requires a more extensive formulation than is used for common (small strain) consolidation problems. Large strain consolidation theories have traditionally been limited to 1-D formulations. SoilVision Systems has developed the capacity to analyze large strain consolidation problems in 2 and 3-D. The benchmarking of such formulations is not a trivial task. This paper presents several examples of modeling large strain consolidation in the beta versions of the new software. These examples were taken from the literature and were used to benchmark the large strain formulation used by the new software. The benchmarks reported here are: a comparison to the consolidation software application CONDES0, Townsend's Scenario B and a multi-dimensional analysis of long-term column tests performed on oil sands tailings. All three of these benchmarks were attained using the SVOffice suite. (author)

  18. Large-Strain Transparent Magnetoactive Polymer Nanocomposites

    Science.gov (United States)

    Meador, Michael A.

    2012-01-01

    A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

  19. Nature of interstitially induced lattice strains

    International Nuclear Information System (INIS)

    Emin, D.

    1978-01-01

    The addition of interstitial atoms to a metal lattice has been likened to the addition of extra billiard balls to an array of tangentially touching billiard balls. In such a picture the increased clustering of interstitials can lead to the buildup of larger and larger strain fields which ultimately are associated with the production of broken bonds. Simple models of the strain fields associated with the addition of particles to a lattice in which the force exerted between the added atoms and host atoms is finite have been studied. From these studies one can define situations in which the billiard-ball approach has qualitative validity and those in which it is inappropriate. Basically, those situations in which the displacements of the host atoms can be represented as involving acoustic phonons yield long-range strain fields analogous to those of the billiard-ball model with the radius of the extra billiard ball being determined by the stiffness of the host lattice and the forces between the added atom and the surrounding host atoms. If the displacements produced by the added atoms are represented as involving primarily optical phonons the displacement pattern is short-ranged and not described by the usual elasticity theory. For example, Vegard's law does not apply in these instances. Such concerns arise in considering the strains induced by interstitial helium in tritides

  20. Interpretation of large-strain geophysical crosshole tests

    International Nuclear Information System (INIS)

    Drnevich, V.P.; Salgado, R.; Ashmawy, A.; Grant, W.P.; Vallenas, P.

    1995-10-01

    At sites in earthquake-prone areas, the nonlinear dynamic stress-strain behavior of soil with depth is essential for earthquake response analyses. A seismic crosshole test has been developed where large dynamic forces are applied in a borehole. These forces generate shear strains in the surrounding soil that are well into the nonlinear range. The shear strain amplitudes decrease with distance from the source. Velocity sensors located in three additional holes at various distances from the source hole measure the particle velocity and the travel time of the shear wave from the source. This paper provides an improved, systematic interpretation scheme for the data from these large-strain geophysical crosshole tests. Use is made of both the measured velocities at each sensor and the travel times. The measured velocity at each sensor location is shown to be a good measure of the soil particle velocity at that location. Travel times to specific features on the velocity time history, such as first crossover, are used to generate travel time curves for the waves which are nonlinear. At some distance the amplitudes reduce to where the stress-strain behavior is essentially linear and independent of strain amplitude. This fact is used together with the measurements at the three sensor locations in a rational approach for fitting curves of shear wave velocity versus distance from the source hole that allow the determination of the shear wave velocity and the shear strain amplitude at each of the sensor locations as well as the shear wave velocity associated with small-strain (linear) behavior. The method is automated using off-the-shelf PC-based software. The method is applied to large-strain crosshole tests performed as part of the studies for the design and construction of the proposed Multi-Function Waste Tank Facility planned for Hanford Site

  1. Polymer film strain gauges for measuring large elongations

    Science.gov (United States)

    Kondratov, A. P.; Zueva, A. M.; Varakin, R. S.; Taranec, I. P.; Savenkova, I. A.

    2018-02-01

    The paper shows the possibility to print polymer strain gages, microstrip lines, coplanar waveguides, and other prints for avionics using printing technology and equipment. The methods of screen and inkjet printing have been complemented by three new operations of preparing print films for application of an electrically conductive ink layer. Such additional operations make it possible to enhance the conductive ink layer adhesion to the film and to manufacture strain gages for measuring large elongations.

  2. Substrate-induced strain in carbon nanodisks

    International Nuclear Information System (INIS)

    Osváth, Z.; Vértesy, Z.; Lábár, J.; Nemes-Incze, P.; Horváth, Z.E.; Biró, L.P.

    2014-01-01

    Graphitic nanodisks of typically 20–50 nm in thickness, produced by the so-called Kvaerner Carbon Black and Hydrogen Process were dispersed on gold substrate and investigated by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and confocal Raman spectroscopy. The roughness of the gold surface was drastically changed by annealing at 400 °C. AFM measurements show that this change in the surface roughness induces changes also in the topography of the nanodisks, as they closely follow the corrugation of the gold substrate. This leads to strained nanodisks, which is confirmed also by confocal Raman microscopy. We found that the FE-SEM contrast obtained from the disks depends on the working distance used during the image acquisition by In-lens detection, a phenomenon which we explain by the decrease in the amount of electrons reaching the detector due to diffraction. This process may affect the image contrast in the case of other layered materials, like hexagonal boron nitride, and other planar hybrid nanostructures, too. - Highlights: • Bending of carbon nanodisks is induced by the roughness of the gold substrate. • Confocal Raman microscopy shows a compressive strain induced in the nanodisks. • The electron microscopy contrast of nanodisks depends on the working distance

  3. Mechanical strength model for plastic bonded granular materials at high strain rates and large strains

    International Nuclear Information System (INIS)

    Browning, R.V.; Scammon, R.J.

    1998-01-01

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-9501. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate that the observed characteristic behavior is captured by this viscoelastic based model. copyright 1998 American Institute of Physics

  4. Large Strain Transparent Magneto-Active Polymer Nanocomposites

    Science.gov (United States)

    Yoonessi, Mitra (Inventor); Meador, Michael A (Inventor)

    2016-01-01

    A large strain polymer nanocomposite actuator is provided that upon subjected to an external stimulus, such as a magnetic field (static or electromagnetic field), an electric field, thermal energy, light, etc., will deform to thereby enable mechanical manipulations of structural components in a remote and wireless manner.

  5. Influence of plastic strain on deformation-induced martensitic transformations

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Groen, M.

    2008-01-01

    The effects of plastic strain on deformation-induced martensitic transformations have been investigated experimentally. Austenitic metastable stainless steel samples were heated to a temperature at which the transformation is suppressed and were plastically strained to different amounts. The

  6. WIPP Benchmark calculations with the large strain SPECTROM codes

    International Nuclear Information System (INIS)

    Callahan, G.D.; DeVries, K.L.

    1995-08-01

    This report provides calculational results from the updated Lagrangian structural finite-element programs SPECTROM-32 and SPECTROM-333 for the purpose of qualifying these codes to perform analyses of structural situations in the Waste Isolation Pilot Plant (WIPP). Results are presented for the Second WIPP Benchmark (Benchmark II) Problems and for a simplified heated room problem used in a parallel design calculation study. The Benchmark II problems consist of an isothermal room problem and a heated room problem. The stratigraphy involves 27 distinct geologic layers including ten clay seams of which four are modeled as frictionless sliding interfaces. The analyses of the Benchmark II problems consider a 10-year simulation period. The evaluation of nine structural codes used in the Benchmark II problems shows that inclusion of finite-strain effects is not as significant as observed for the simplified heated room problem, and a variety of finite-strain and small-strain formulations produced similar results. The simplified heated room problem provides stratigraphic complexity equivalent to the Benchmark II problems but neglects sliding along the clay seams. The simplified heated problem does, however, provide a calculational check case where the small strain-formulation produced room closures about 20 percent greater than those obtained using finite-strain formulations. A discussion is given of each of the solved problems, and the computational results are compared with available published results. In general, the results of the two SPECTROM large strain codes compare favorably with results from other codes used to solve the problems

  7. Material-Point Analysis of Large-Strain Problems

    DEFF Research Database (Denmark)

    Andersen, Søren

    The aim of this thesis is to apply and improve the material-point method for modelling of geotechnical problems. One of the geotechnical phenomena that is a subject of active research is the study of landslides. A large amount of research is focused on determining when slopes become unstable. Hence......, it is possible to predict if a certain slope is stable using commercial finite element or finite difference software such as PLAXIS, ABAQUS or FLAC. However, the dynamics during a landslide are less explored. The material-point method (MPM) is a novel numerical method aimed at analysing problems involving...... materials subjected to large strains in a dynamical time–space domain. This thesis explores the material-point method with the specific aim of improving the performance for geotechnical problems. Large-strain geotechnical problems such as landslides pose a major challenge to model numerically. Employing...

  8. Fabric strain sensor integrated with CNPECs for repeated large deformation

    Science.gov (United States)

    Yi, Weijing

    Flexible and soft strain sensors that can be used in smart textiles for wearable applications are much desired. They should meet the requirements of low modulus, large working range and good fatigue resistance as well as good sensing performances. However, there were no commercial products available and the objective of the thesis is to investigate fabric strain sensors based on carbon nanoparticle (CNP) filled elastomer composites (CNPECs) for potential wearing applications. Conductive CNPECs were fabricated and investigated. The introduction of silicone oil (SO) significantly decreased modulus of the composites to less than 1 MPa without affecting their deformability and they showed good stability after heat treatment. With increase of CNP concentration, a percolation appeared in electrical resistivity and the composites can be divided into three ranges. I-V curves and impedance spectra together with electro-mechanical studies demonstrated a balance between sensitivity and working range for the composites with CNP concentrations in post percolation range, and were preferred for sensing applications only if the fatigue life was improved. Due to the good elasticity and failure resist property of knitted fabric under repeated extension, it was adopted as substrate to increase the fatigue life of the conductive composites. After optimization of processing parameters, the conductive fabric with CNP concentration of 9.0CNP showed linear I-V curves when voltage is in the range of -1 V/mm and 1 V/mm and negligible capacitive behavior when frequency below 103 Hz even with strain of 60%. It showed higher sensitivity due to the combination of nonlinear resistance-strain behavior of the CNPECs and non-even strain distribution of knitted fabric under extension. The fatigue life of the conductive fabric was greatly improved. Extended on the studies of CNPECs and the coated conductive fabrics, a fabric strain sensor was designed, fabricated and packaged. The Young's modulus of

  9. Metallic nanomaterials formed by exerting large plastic strains

    International Nuclear Information System (INIS)

    Richert, M; Richert, J.; Zasadzinski, J.; Hawrylkiewicz, S.

    2002-01-01

    The investigations included pure Al and Cu single crystals, AlMg5 alloy and AlCuZr alloy have been presented. The materials were deformed by the cyclic extrusion compression method (CEC) within the range of true strains φ = 0.4-59.8 (1 to 67 deformation cycles by the CEC method). In all examined materials a strong tendency to form banded was observed. Within the range of very large plastic strains there was observed intensive rebuilding of the banded microstructure into subgrains, at first of rhombic shape, and next into equiaxial subgrains. A characteristic feature of the newly formed subgrains, not encountered in the range of conventional deformations, was the occurrence of large misorientation angles between the newly formed subgrains. The proportion of large misorientation angles in the microstructure varied, and it increased with increasing deformation. Reduction of the recovery process in AlMg5 and AlCuZr alloys preserved the growth of the newly formed nanograins, favoring the retaining of the nanomeric dimensions. This results show that there is the effective possibility of production of metallic nanomaterials by exerting of very large nonconventional plastic strains. (author)

  10. Flexible textile-based strain sensor induced by contacts

    International Nuclear Information System (INIS)

    Zhang, Hui

    2015-01-01

    In this paper, the contact effects are used as the key sensing element to develop flexible textile-structured strain sensors. The structures of the contact are analyzed theoretically and the contact resistances are investigated experimentally. The electromechanical properties of the textiles are investigated to find the key factors which determine the sensitivity, repeatability, and linearity of the sensor. The sensing mechanism is based on the change of contact resistance induced by the change of the configuration of the textiles. In order to improve the performance of the textile strain sensor, the contact resistance is designed based on the electromechanical properties of the fabric. It can be seen from the results that the performance of the sensor is largely affected by the structure of the contacts, which are determined by the morphology of fiber surface and the structures of the yarn and fabric. (paper)

  11. Strain induced anomalous red shift in mesoscopic iron oxide ...

    Indian Academy of Sciences (India)

    Wintec

    pared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the ..... Shape control can also induce anisotropy and thus modify the coercivity of these ... ppines: Addison-Wesley Publishing Company).

  12. High Strain Rate and Shock-Induced Deformation in Metals

    Science.gov (United States)

    Ravelo, Ramon

    2012-02-01

    Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as

  13. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.

    2012-04-17

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  14. Strain-induced changes to the electronic structure of germanium

    KAUST Repository

    Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Dimoulas, Athanasios Dimoulas

    2012-01-01

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  15. The behavior of intermetallic compounds at large plastic strains

    International Nuclear Information System (INIS)

    Gray, G.T.; Embury, J.D.

    1993-01-01

    This paper contains a summary of a broad study of intermetallics which includes the following materials, Ni 3 Al, Ti-48Al-1V, Ti-24Al-11Nb, Ti-48Al-2Cr-2Nb, and Ti-24.5 Al-10.5Nb-1.5Mo. Much effort has been devoted to the study of ordered materials at modes plastic strains and the problem of premature failure. However by utilizing stress states other than simple tension it is possible to study the deformation of intermetallic compounds up to large plastic strains and to consider the behavior of these materials in the regime where stresses approach the theoretical stress. The current work outlines studies of the work hardening rate of a number of titanium and nickel-based intermetallic compounds deformed in compression. Attention is given to the structural basis of the sustained work hardening. The large strain plasticity of these materials is summarized in a series of diagrams. Fracture in these materials in compression occurs via catastrophic shear at stresses of the order of E/80 (where E is the elastic modulus)

  16. Shear banding in large strain plasticity - Influence of specimen dimensions

    Science.gov (United States)

    Mucha, Marzena; Wcisło, Balbina; Pamin, Jerzy

    2018-01-01

    The paper deals with numerical analysis of shear banding which occurs in an elongated rectangular plate for a large strain elastic-plastic material model. It is focused on the influence of plate size proportions and finite element mesh density on numerical results. The discussion is limited to isothermal conditions and ideal plasticity. First a plain strain case is computed for different lengths of the plate, then simulations are repeated for plane stress for which different thicknesses of the plate are considered. Most of the computations are performed for three finite element meshes to verify discretization sensitivity of the results. The simulations are performed using AceGen and AceFEM packages for Wolfram Mathematica.

  17. A mathematical formulation for large strain analysis of geologic continua

    International Nuclear Information System (INIS)

    Chaudhary, A.B.; Vakili, J.E.; Hume, H.R.

    1987-12-01

    A solution method is presented for finite-deformation analysis of geologic materials. The principle of virtual work is used to state the equations of equilibrium in a weak form. These equations are linearized about the last-established equilibrium configuration. A material constitutive relationship between the Green-Naghdi stress rate and the rate-of-deformation tensor is used to obtain the current stresses. The finite-element governing equations are expressed in a form suitable for an iterative solution strategy. The obtained gradient matrix contains the effects of both material and geometric nonlinearities. The primary application area of this formulation is the analysis of long-term deformation response of the region adjoining the mining shafts and the waste emplacement rooms within a nuclear waste repository. In this region, the strains are expected to be large, and the infinitesimal strain analysis would introduce inaccuracies in the solution. 19 refs., 6 figs

  18. Large isosymmetric reorientation of oxygen octahedra rotation axes in epitaxially strained perovskites.

    Science.gov (United States)

    Rondinelli, James M; Coh, Sinisa

    2011-06-10

    Using first-principles density functional theory calculations, we discover an anomalously large biaxial strain-induced octahedral rotation axis reorientation in orthorhombic perovskites with tendency towards rhombohedral symmetry. The transition between crystallographically equivalent (isosymmetric) structures with different octahedral rotation magnitudes originates from strong strain-octahedral rotation coupling available to perovskites and the energetic hierarchy among competing octahedral tilt patterns. By elucidating these criteria, we suggest many functional perovskites would exhibit the transition in thin film form, thus offering a new landscape in which to tailor highly anisotropic electronic responses.

  19. Formation of strain-induced quantum dots in gated semiconductor nanostructures

    Directory of Open Access Journals (Sweden)

    Ted Thorbeck

    2015-08-01

    Full Text Available A long-standing mystery in the field of semiconductor quantum dots (QDs is: Why are there so many unintentional dots (also known as disorder dots which are neither expected nor controllable. It is typically assumed that these unintentional dots are due to charged defects, however the frequency and predictability of the location of the unintentional QDs suggests there might be additional mechanisms causing the unintentional QDs besides charged defects. We show that the typical strains in a semiconductor nanostructure from metal gates are large enough to create strain-induced quantum dots. We simulate a commonly used QD device architecture, metal gates on bulk silicon, and show the formation of strain-induced QDs. The strain-induced QD can be eliminated by replacing the metal gates with poly-silicon gates. Thus strain can be as important as electrostatics to QD device operation operation.

  20. Angiogenesis is induced by airway smooth muscle strain.

    Science.gov (United States)

    Hasaneen, Nadia A; Zucker, Stanley; Lin, Richard Z; Vaday, Gayle G; Panettieri, Reynold A; Foda, Hussein D

    2007-10-01

    Angiogenesis is an important feature of airway remodeling in both chronic asthma and chronic obstructive pulmonary disease (COPD). Airways in those conditions are exposed to excessive mechanical strain during periods of acute exacerbations. We recently reported that mechanical strain of human airway smooth muscle (HASM) led to an increase in their proliferation and migration. Sustained growth in airway smooth muscle in vivo requires an increase in the nutritional supply to these muscles, hence angiogenesis. In this study, we examined the hypothesis that cyclic mechanical strain of HASM produces factors promoting angiogenic events in the surrounding vascular endothelial cells. Our results show: 1) a significant increase in human lung microvascular endothelial cell (HMVEC-L) proliferation, migration, and tube formation following incubation in conditioned media (CM) from HASM cells exposed to mechanical strain; 2) mechanical strain of HASM cells induced VEGF expression and release; 3) VEGF neutralizing antibodies inhibited the proliferation, migration, and tube formations of HMVEC-L induced by the strained airway smooth muscle CM; 4) mechanical strain of HASM induced a significant increase in hypoxia-inducible factor-1alpha (HIF-1alpha) mRNA and protein, a transcription factor required for VEGF gene transcription; and 5) mechanical strain of HASM induced HIF-1alpha/VEGF through dual phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and ERK pathways. In conclusion, exposing HASM cells to mechanical strain induces signal transduction pathway through PI3K/Akt/mTOR and ERK pathways that lead to an increase in HIF-1alpha, a transcription factor required for VEGF expression. VEGF release by mechanical strain of HASM may contribute to the angiogenesis seen with repeated exacerbation of asthma and COPD.

  1. Strain induced anomalous red shift in mesoscopic iron oxide

    Indian Academy of Sciences (India)

    Nano magnetic oxides; red shift; magnetic storage. ... size and strain induced modifications of various physical properties viz. optical, magnetic and structural. ... ∼2, are synthesized by employing starch and ethylene glycol and starch and ...

  2. Strain-Induced Ferromagnetism in Antiferromagnetic LuMnO3 Thin Films

    Science.gov (United States)

    White, J. S.; Bator, M.; Hu, Y.; Luetkens, H.; Stahn, J.; Capelli, S.; Das, S.; Döbeli, M.; Lippert, Th.; Malik, V. K.; Martynczuk, J.; Wokaun, A.; Kenzelmann, M.; Niedermayer, Ch.; Schneider, C. W.

    2013-07-01

    Single phase and strained LuMnO3 thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

  3. Strain induced optical properties of BaReO3

    Science.gov (United States)

    Kumavat, Sandip R.; Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

    2018-05-01

    Here, we have performed strain induce optical properties of BaReO3 by using density functional theory (DFT). We noticed that after applying intrinsic and extrinsic strain to the BaReO3, it shows the metallic behavior. We also studied optical properties, which show good activity in the ultraviolet region. The results show that after applying intrinsic and extrinsic strain to BaReO3 the absorption peaks are shifted towards the high UV region of the spectrum. Thus, we concluded that, BaReO3 material with extrinsic strain can be useful for high frequency UV device and optoelectronic devices.

  4. Transfer induced compressive strain in graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget; Mackenzie, David; Caridad, Jose

    2014-01-01

    We have used spatially resolved micro Raman spectroscopy to map the full width at half maximum (FWHM) of the graphene G-band and the 2D and G peak positions, for as-grown graphene on copper catalyst layers, for transferred CVD graphene and for micromechanically exfoliated graphene, in order...... to characterize the effects of a transfer process on graphene properties. Here we use the FWHM(G) as an indicator of the doping level of graphene, and the ratio of the shifts in the 2D and G bands as an indicator of strain. We find that the transfer process introduces an isotropic, spatially uniform, compressive...... strain in graphene, and increases the carrier concentration....

  5. Suppressing molecular vibrations in organic semiconductors by inducing strain.

    Science.gov (United States)

    Kubo, Takayoshi; Häusermann, Roger; Tsurumi, Junto; Soeda, Junshi; Okada, Yugo; Yamashita, Yu; Akamatsu, Norihisa; Shishido, Atsushi; Mitsui, Chikahiko; Okamoto, Toshihiro; Yanagisawa, Susumu; Matsui, Hiroyuki; Takeya, Jun

    2016-04-04

    Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors. Improving the performance of organic semiconductor devices by increasing the charge mobility is an ongoing quest, which calls for novel molecular and material design, and improved processing conditions. Here we show a method to increase the charge mobility in organic single-crystal field-effect transistors, by taking advantage of the inherent softness of organic semiconductors. We compress the crystal lattice uniaxially by bending the flexible devices, leading to an improved charge transport. The mobility increases from 9.7 to 16.5 cm(2) V(-1) s(-1) by 70% under 3% strain. In-depth analysis indicates that compressing the crystal structure directly restricts the vibration of the molecules, thus suppresses dynamic disorder, a unique mechanism in organic semiconductors. Since strain can be easily induced during the fabrication process, we expect our method to be exploited to build high-performance organic devices.

  6. The Strain Energy, Seismic Moment and Magnitudes of Large Earthquakes

    Science.gov (United States)

    Purcaru, G.

    2004-12-01

    The strain energy Est, as potential energy, released by an earthquake and the seismic moment Mo are two fundamental physical earthquake parameters. The earthquake rupture process ``represents'' the release of the accumulated Est. The moment Mo, first obtained in 1966 by Aki, revolutioned the quantification of earthquake size and led to the elimination of the limitations of the conventional magnitudes (originally ML, Richter, 1930) mb, Ms, m, MGR. Both Mo and Est, not in a 1-to-1 correspondence, are uniform measures of the size, although Est is presently less accurate than Mo. Est is partitioned in seismic- (Es), fracture- (Eg) and frictional-energy Ef, and Ef is lost as frictional heat energy. The available Est = Es + Eg (Aki and Richards (1980), Kostrov and Das, (1988) for fundamentals on Mo and Est). Related to Mo, Est and Es, several modern magnitudes were defined under various assumptions: the moment magnitude Mw (Kanamori, 1977), strain energy magnitude ME (Purcaru and Berckhemer, 1978), tsunami magnitude Mt (Abe, 1979), mantle magnitude Mm (Okal and Talandier, 1987), seismic energy magnitude Me (Choy and Boatright, 1995, Yanovskaya et al, 1996), body-wave magnitude Mpw (Tsuboi et al, 1998). The available Est = (1/2μ )Δ σ Mo, Δ σ ~=~average stress drop, and ME is % \\[M_E = 2/3(\\log M_o + \\log(\\Delta\\sigma/\\mu)-12.1) ,\\] % and log Est = 11.8 + 1.5 ME. The estimation of Est was modified to include Mo, Δ and μ of predominant high slip zones (asperities) to account for multiple events (Purcaru, 1997): % \\[E_{st} = \\frac{1}{2} \\sum_i {\\frac{1}{\\mu_i} M_{o,i} \\Delta\\sigma_i} , \\sum_i M_{o,i} = M_o \\] % We derived the energy balance of Est, Es and Eg as: % \\[ E_{st}/M_o = (1+e(g,s)) E_s/M_o , e(g,s) = E_g/E_s \\] % We analyzed a set of about 90 large earthquakes and found that, depending on the goal these magnitudes quantify differently the rupture process, thus providing complementary means of earthquake characterization. Results for some

  7. Strain-induced shear instability in Liverpool Bay

    Science.gov (United States)

    Wihsgott, Juliane; Palmer, Matthew R.

    2013-04-01

    Liverpool Bay is a shallow subsection of the eastern Irish Sea with large tides (10 m), which drive strong tidal currents (1 ms-1). The Bay is heavily influenced by large freshwater inputs from several Welsh and English rivers that maintain a strong and persistent horizontal density gradient. This gradient interacts with the sheared tidal currents to strain freshwater over denser pelagic water on a semi-diurnal frequency. This Strain-Induced-Periodic-Stratification (SIPS) has important implications on vertical and horizontal mixing. The subtle interaction between stratification and turbulence in this complex environment is shown to be of critical importance to freshwater transport, and subsequently the fate of associated biogeochemical and pollutant pathways. Recent work identified an asymmetry of current ellipses due to SIPS that increases shear instability in the halocline with the potential to enhance diapycnal mixing. Here, we use data from a short, high intensity process study which reveals this mid-water mechanism maintains prolonged periods of sub-critical gradient Richardson number (Ri ≤ ¼) that suggests shear instability is likely. A time series of measurements from a microstructure profiler identifies the associated increase in turbulence is short lived and 'patchy' but sufficient to promote diapycnal mixing. The significance of this mixing process is further investigated by comparing our findings with long-term observations from the Liverpool Bay Coastal Observatory. We identify that the conditions for shear instability during SIPS are regularly met and suggest that this process contributes to the current underestimates of near coastal mixing observed in regional models. To assist our understanding of the observed processes and to test the current capability of turbulence 'closure schemes' we employ a one-dimensional numerical model to investigate the physical mechanisms driving diapycnal mixing in Liverpool Bay.

  8. Large-strain Soft Sensors Using Elastomers Blended with Exfoliated/Fragmented Graphite Particles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sungmin; Nam, Gyungmok; Kim, Jonghun; Yoon, Sang-Hee [Inha Univ., Incheon (Korea, Republic of)

    2016-09-15

    An elastic polymer (e.g., PDMS) blended with EFG particles is a promising conductive composite for fabricating soft sensors that can detect an object's deformation up to or more than 50 %. Here, we develop large-strain, sprayable soft sensors using a mixture of PDMS and EFG particles, which are used as a host elastomer and electrically conductive particles, respectively. A solution for a conductive composite mixture is prepared by the microwave-assisted graphite exfoliation, followed by ultrasonication-induced fragmentation of the exfoliated graphite and ultrasonic blending of PDMS and EFG. Using the prepared solutions for composite and pure PDMS, 1-, 2-, and 3-axis soft sensors are fabricated by airbrush stencil technique where composite mixture and pure PDMS are materials for sensing and insulating layers, respectively. We characterize the soft strain sensors after investigating the effect of PDMS/EFG wt % on mechanical compliance and electrical conductance of the conductive composite.

  9. Strain-induced generation of silicon nanopillars

    International Nuclear Information System (INIS)

    Bollani, Monica; Osmond, Johann; Nicotra, Giuseppe; Spinella, Corrado; Narducci, Dario

    2013-01-01

    Silicon metal-assisted chemical etching (MACE) is a nanostructuring technique exploiting the enhancement of the silicon etch rate at some metal–silicon interfaces. Compared to more traditional approaches, MACE is a high-throughput technique, and it is one of the few that enables the growth of vertical 1D structures of virtually unlimited length. As such, it has already found relevant technological applications in fields ranging from energy conversion to biosensing. Yet, its implementation has always required metal patterning to obtain nanopillars. Here, we report how MACE may lead to the formation of porous silicon nanopillars even in the absence of gold patterning. We show how the use of inhomogeneous yet continuous gold layers leads to the generation of a stress field causing spontaneous local delamination of the metal—and to the formation of silicon nanopillars where the metal disruption occurs. We observed the spontaneous formation of nanopillars with diameters ranging from 40 to 65 nm and heights up to 1 μm. Strain-controlled generation of nanopillars is consistent with a mechanism of silicon oxidation by hole injection through the metal layer. Spontaneous nanopillar formation could enable applications of this method to contexts where ordered distributions of nanopillars are not required, while patterning by high-resolution techniques is either impractical or unaffordable. (paper)

  10. Cyclic loading of simulated fault gouge to large strains

    Science.gov (United States)

    Jones, Lucile M.

    1980-04-01

    As part of a study of the mechanics of simulated fault gouge, deformation of Kayenta Sandstone (24% initial porosity) was observed in triaxial stress tests through several stress cycles. Between 50- and 300-MPa effective pressure the specimens deformed stably without stress drops and with deformation occurring throughout the sample. At 400-MPa effective pressure the specimens underwent strain softening with the deformation occurring along one plane. However, the difference in behavior seems to be due to the density variation at different pressures rather than to the difference in pressure. After peak stress was reached in each cycle, the samples dilated such that the volumetric strain and the linear strain maintained a constant ratio (approximately 0.1) at all pressures. The behavior was independent of the number of stress cycles to linear strains up to 90% and was in general agreement with laws of soil behavior derived from experiments conducted at low pressure (below 5 MPa).

  11. A wireless sensor network design and evaluation for large structural strain field monitoring

    International Nuclear Information System (INIS)

    Qiu, Zixue; Wu, Jian; Yuan, Shenfang

    2011-01-01

    Structural strain changes under external environmental or mechanical loads are the main monitoring parameters in structural health monitoring or mechanical property tests. This paper presents a wireless sensor network designed for monitoring large structural strain field variation. First of all, a precision strain sensor node is designed for multi-channel strain gauge signal conditioning and wireless monitoring. In order to establish a synchronous strain data acquisition network, the cluster-star network synchronization method is designed in detail. To verify the functionality of the designed wireless network for strain field monitoring capability, a multi-point network evaluation system is developed for an experimental aluminum plate structure for load variation monitoring. Based on the precision wireless strain nodes, the wireless data acquisition network is deployed to synchronously gather, process and transmit strain gauge signals and monitor results under concentrated loads. This paper shows the efficiency of the wireless sensor network for large structural strain field monitoring

  12. Laser-induced photo-thermal strain imaging

    Science.gov (United States)

    Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

    2018-02-01

    Vulnerable plaque is the one of the leading causes of cardiovascular disease occurrence. However, conventional intravascular imaging techniques suffer from difficulty in finding vulnerable plaque due to limitation such as lack of physiological information, imaging depth, and depth sensitivity. Therefore, new techniques are needed to help determine the vulnerability of plaque, Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed that varies with temperature of medium. During temperature increase, strain occurs in the medium and its variation tendency is depending on the type of tissue, which makes it possible to use for tissue differentiation. Here, we demonstrate laser-induced photo-thermal strain imaging (pTSI) to differentiate tissue using an intravascular ultrasound (IVUS) catheter and a 1210-nm continuous-wave laser for heating lipids intensively. During heating, consecutive US images were obtained from a custom-made phantom made of porcine fat and gelatin. A cross correlation-based speckle-tracking algorithm was then applied to calculate the strain of US images. In the strain images, the positive strain produced in lipids (porcine fat) was clearly differentiated from water-bearing tissue (gelatin). This result shows that laser-induced pTSI could be a new method to distinguish lipids in the plaque and can help to differentiate vulnerability of plaque.

  13. Enhanced thermo-mechanical performance and strain-induced ...

    Indian Academy of Sciences (India)

    Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films ... School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea; School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea ...

  14. Self-adapted and tunable graphene strain sensors for detecting both subtle and large human motions.

    Science.gov (United States)

    Tao, Lu-Qi; Wang, Dan-Yang; Tian, He; Ju, Zhen-Yi; Liu, Ying; Pang, Yu; Chen, Yuan-Quan; Yang, Yi; Ren, Tian-Ling

    2017-06-22

    Conventional strain sensors rarely have both a high gauge factor and a large strain range simultaneously, so they can only be used in specific situations where only a high sensitivity or a large strain range is required. However, for detecting human motions that include both subtle and large motions, these strain sensors can't meet the diverse demands simultaneously. Here, we come up with laser patterned graphene strain sensors with self-adapted and tunable performance for the first time. A series of strain sensors with either an ultrahigh gauge factor or a preferable strain range can be fabricated simultaneously via one-step laser patterning, and are suitable for detecting all human motions. The strain sensors have a GF of up to 457 with a strain range of 35%, or have a strain range of up to 100% with a GF of 268. Most importantly, the performance of the strain sensors can be easily tuned by adjusting the patterns of the graphene, so that the sensors can meet diverse demands in both subtle and large motion situations. The graphene strain sensors show significant potential in applications such as wearable electronics, health monitoring and intelligent robots. Furthermore, the facile, fast and low-cost fabrication method will make them possible and practical to be used for commercial applications in the future.

  15. Large area strain analysis using scanning transmission electron microscopy across multiple images

    International Nuclear Information System (INIS)

    Oni, A. A.; Sang, X.; LeBeau, J. M.; Raju, S. V.; Saxena, S.; Dumpala, S.; Broderick, S.; Rajan, K.; Kumar, A.; Sinnott, S.

    2015-01-01

    Here, we apply revolving scanning transmission electron microscopy to measure lattice strain across a sample using a single reference area. To do so, we remove image distortion introduced by sample drift, which usually restricts strain analysis to a single image. Overcoming this challenge, we show that it is possible to use strain reference areas elsewhere in the sample, thereby enabling reliable strain mapping across large areas. As a prototypical example, we determine the strain present within the microstructure of a Ni-based superalloy directly from atom column positions as well as geometric phase analysis. While maintaining atomic resolution, we quantify strain within nanoscale regions and demonstrate that large, unit-cell level strain fluctuations are present within the intermetallic phase

  16. A model for recovery kinetics of aluminum after large strain

    DEFF Research Database (Denmark)

    Yu, Tianbo; Hansen, Niels

    2012-01-01

    A model is suggested to analyze recovery kinetics of heavily deformed aluminum. The model is based on the hardness of isothermal annealed samples before recrystallization takes place, and it can be extrapolated to longer annealing times to factor out the recrystallization component of the hardness...... for conditions where recovery and recrystallization overlap. The model is applied to the isothermal recovery at temperatures between 140 and 220°C of commercial purity aluminum deformed to true strain 5.5. EBSD measurements have been carried out to detect the onset of discontinuous recrystallization. Furthermore...

  17. Actin and microtubule networks contribute differently to cell response for small and large strains

    Science.gov (United States)

    Kubitschke, H.; Schnauss, J.; Nnetu, K. D.; Warmt, E.; Stange, R.; Kaes, J.

    2017-09-01

    Cytoskeletal filaments provide cells with mechanical stability and organization. The main key players are actin filaments and microtubules governing a cell’s response to mechanical stimuli. We investigated the specific influences of these crucial components by deforming MCF-7 epithelial cells at small (≤5% deformation) and large strains (>5% deformation). To understand specific contributions of actin filaments and microtubules, we systematically studied cellular responses after treatment with cytoskeleton influencing drugs. Quantification with the microfluidic optical stretcher allowed capturing the relative deformation and relaxation of cells under different conditions. We separated distinctive deformational and relaxational contributions to cell mechanics for actin and microtubule networks for two orders of magnitude of drug dosages. Disrupting actin filaments via latrunculin A, for instance, revealed a strain-independent softening. Stabilizing these filaments by treatment with jasplakinolide yielded cell softening for small strains but showed no significant change at large strains. In contrast, cells treated with nocodazole to disrupt microtubules displayed a softening at large strains but remained unchanged at small strains. Stabilizing microtubules within the cells via paclitaxel revealed no significant changes for deformations at small strains, but concentration-dependent impact at large strains. This suggests that for suspended cells, the actin cortex is probed at small strains, while at larger strains; the whole cell is probed with a significant contribution from the microtubules.

  18. Strain-induced chiral magnetic effect in Weyl semimetals

    International Nuclear Information System (INIS)

    Cortijo, Alberto; Kharzeev, Dmitri; Vozmediano, Maria A. H.

    2016-01-01

    Here, we argue that strain applied to a time-reversal and inversion breaking Weyl semimetal in a magnetic field can induce an electric current via the chiral magnetic effect. A tight-binding model is used to show that strain generically changes the locations in the Brillouin zone but also the energies of the band touching points (tips of the Weyl cones). Since axial charge in a Weyl semimetal can relax via intervalley scattering processes, the induced current will decay with a time scale given by the lifetime of a chiral quasiparticle. Lastly, we estimate the strength and lifetime of the current for typical material parameters and find that it should be experimentally observable.

  19. Structure and properties of copper after large strain deformation

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Molak, Rafal M.; Pakiela, Zbigniew

    2010-05-15

    Structure and properties of Cu in dependence on strain (from {epsilon}{proportional_to} 0.9 to {epsilon}{proportional_to} 15) during multi-axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The mechanical properties of yield strength (YS), ultimate tensile strength (UTS) and uniform elongation was performed on MTS QTest/10 machine equipped with digital image correlation method (DIC). The structure-flow stress relationship of multi-axial compression processing material at strains {epsilon}{proportional_to} 3.5 and {epsilon}{proportional_to} 5.5 is discussed. It is found that processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recrystallization plays an important role during multi-axial compression process in this range of deformation (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Dynamic strain-induced transformation: An atomic scale investigation

    International Nuclear Information System (INIS)

    Zhang, H.; Pradeep, K.G.; Mandal, S.; Ponge, D.; Springer, H.; Raabe, D.

    2015-01-01

    Phase transformations provide the most versatile access to the design of complex nanostructured alloys in terms of grain size, morphology, local chemical constitution etc. Here we study a special case of deformation induced phase transformation. More specifically, we investigate the atomistic mechanisms associated with dynamic strain-induced transformation (DSIT) in a dual-phased multicomponent iron-based alloy at high temperatures. DSIT phenomena and the associated secondary phase nucleation were observed at atomic scale using atom probe tomography. The obtained local chemical composition was used for simulating the nucleation process which revealed that DSIT, occurring during load exertion, proceeds by a diffusion-controlled nucleation process

  1. Plastic strain induced damage evolution and martensitic transformation in ductile materials at cryogenic temperatures

    International Nuclear Information System (INIS)

    Garion, C.; Skoczen, B.T.

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behavior at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of these irreversible phenomena, associated with the dissipation of plastic power, are included into the constitutive model of stainless steels at cryogenic temperatures. The model is tested on the thin-walled corrugated shells (known as bellows expansion joints) used in the interconnections of the Large Hadron Collider, the new proton storage ring being constructed at present at CERN

  2. Strain-Induced Spin-Resonance Shifts in Silicon Devices

    Science.gov (United States)

    Pla, J. J.; Bienfait, A.; Pica, G.; Mansir, J.; Mohiyaddin, F. A.; Zeng, Z.; Niquet, Y. M.; Morello, A.; Schenkel, T.; Morton, J. J. L.; Bertet, P.

    2018-04-01

    In spin-based quantum-information-processing devices, the presence of control and detection circuitry can change the local environment of a spin by introducing strain and electric fields, altering its resonant frequencies. These resonance shifts can be large compared to intrinsic spin linewidths, and it is therefore important to study, understand, and model such effects in order to better predict device performance. We investigate a sample of bismuth donor spins implanted in a silicon chip, on top of which a superconducting aluminum microresonator is fabricated. The on-chip resonator provides two functions: it produces local strain in the silicon due to the larger thermal contraction of the aluminum, and it enables sensitive electron spin-resonance spectroscopy of donors close to the surface that experience this strain. Through finite-element strain simulations, we are able to reconstruct key features of our experiments, including the electron spin-resonance spectra. Our results are consistent with a recently observed mechanism for producing shifts of the hyperfine interaction for donors in silicon, which is linear with the hydrostatic component of an applied strain.

  3. International Clostridium difficile animal strain collection and large diversity of animal associated strains

    DEFF Research Database (Denmark)

    Janezic, Sandra; Zidaric, Valerija; Pardon, Bart

    2014-01-01

    Background: Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria...... of one strain (PCR ribotype) per animal species per laboratory. Results: Altogether 112 isolates were collected and distributed into 38 PCR ribotypes with agarose based approach and 50 PCR ribotypes with sequencer based approach. Four PCR ribotypes were most prevalent in terms of number of isolates...... as well as in terms of number of different host species: 078 (14.3% of isolates; 4 hosts), 014/020 (11.6%; 8 hosts); 002 (5.4%; 4 hosts) and 012 (5.4%; 5 hosts). Two animal hosts were best represented; cattle with 31 isolates (20 PCR ribotypes; 7 countries) and pigs with 31 isolates (16 PCR ribotypes; 10...

  4. Origin of strain-induced resonances in flexible terahertz metamaterials

    International Nuclear Information System (INIS)

    Sun Xiu-Yun; Li Xiao-Ning; Xu Hua; Liang Xian-Ting; Zheng Li-Ren; Zhang Xian-Peng; Lu Yue-Hui; Song Wei-Jie; Lee, Young-Pak; Rhee, Joo-Yull

    2016-01-01

    Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate (PEN) substrates. The unit cell of one type consists of two identical split-ring resonators (SRRs) that are arranged face-to-face (i.e., FlexMetaF); the unit cell of the other type has nothing different but is arranged back-to-back (i.e., FlexMetaB). FlexMetaF and FlexMetaB illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive (LC) resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend FlexMetaF and FlexMetaB, the new resonant peaks appear: in the case of FlexMetaF, the peaks are located at the lower frequencies; in the case of FlexMetaB, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from FlexMetaF and FlexMetaB are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices. (paper)

  5. Microstructure and micro-texture evolution during large strain deformation of Inconel alloy IN718

    Energy Technology Data Exchange (ETDEWEB)

    Nayan, Niraj [Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum 695 022 (India); Gurao, N.P. [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016 (India); Narayana Murty, S.V.S., E-mail: susarla.murty@gmail.com [Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum 695 022 (India); Jha, Abhay K.; Pant, Bhanu; George, Koshy M. [Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum 695 022 (India)

    2015-12-15

    The hot deformation behaviour of Inconel alloy IN718 was studied in the temperature range of 950–1100 °C and at strain rates of 0.01 and 1 s{sup −1} with a view to understand the microstructural evolution as a function of strain rate and temperature. For this purpose, a single hit, hot isothermal plane strain compression (PSC) technique was used. The flow curves obtained during PSC exhibited weak flow softening at higher temperatures. Electron backscattered diffraction analysis (EBSD) of the PSC tested samples at the location of maximum strain revealed dynamic recrystallisation occurring at higher temperatures. Based on detailed microstructure and microtexture analyses, it was concluded that single step, large strain deformation has a distinct advantage in the thermo-mechanical processing of Inconel alloy IN718. - Highlights: • Plane strain compression (PSC) on IN718 was conducted. • Evolution of microstructure during large strain deformation was studied. • Flow curves exhibited weak softening at higher temperatures and dipping of the flow curve at a strain rate of 1 s{sup −1}. • Optimization of microstructure and process parameter for hot rolling possible by plane strain compression testing • Dynamic recrystallisation occurs in specimens deformed at higher temperatures and lower strain rates.

  6. Large scale high strain-rate tests of concrete

    Directory of Open Access Journals (Sweden)

    Kiefer R.

    2012-08-01

    Full Text Available This work presents the stages of development of some innovative equipment, based on Hopkinson bar techniques, for performing large scale dynamic tests of concrete specimens. The activity is centered at the recently upgraded HOPLAB facility, which is basically a split Hopkinson bar with a total length of approximately 200 m and with bar diameters of 72 mm. Through pre-tensioning and suddenly releasing a steel cable, force pulses of up to 2 MN, 250 μs rise time and 40 ms duration can be generated and applied to the specimen tested. The dynamic compression loading has first been treated and several modifications in the basic configuration have been introduced. Twin incident and transmitter bars have been installed with strong steel plates at their ends where large specimens can be accommodated. A series of calibration and qualification tests has been conducted and the first real tests on concrete cylindrical specimens of 20cm diameter and up to 40cm length have commenced. Preliminary results from the analysis of the recorded signals indicate proper Hopkinson bar testing conditions and reliable functioning of the facility.

  7. Immobilization induced osteopenia is strain specific in mice

    Directory of Open Access Journals (Sweden)

    Andreas Lodberg

    2015-06-01

    Full Text Available Immobilization causes rapid and massive bone loss. By comparing Botulinum Toxin A (BTX-induced bone loss in mouse strains with different genetic backgrounds we investigated whether the genetic background had an influence on the severity of the osteopenia. Secondly, we investigated whether BTX had systemic effects on bone. Female mice from four inbred mouse strains (BALB/cJ, C57BL/6 J, DBA/2 J, and C3H/HeN were injected unilaterally with BTX (n = 10/group or unilaterally with saline (n = 10/group. Mice were euthanized after 21 days, and the bone properties evaluated using μCT, DXA, bone histomorphometry, and mechanical testing. BTX resulted in substantially lower trabecular bone volume fraction (BV/TV and trabecular thickness in all mouse strains. The deterioration of BV/TV was significantly greater in C57BL/6 J (−57% and DBA/2 J (−60% than in BALB/cJ (−45% and C3H/HeN (−34% mice. The loss of femoral neck fracture strength was significantly greater in C57BL/6 J (−47% and DBA/2 J (−45% than in C3H (−25% mice and likewise the loss of mid-femoral fracture strength was greater in C57BL/6 J (−17%, DBA/2 J (−12%, and BALB/cJ (−9% than in C3H/HeN (−1% mice, which were unaffected. Using high resolution μCT we found no evidence of a systemic effect on any of the microstructural parameters of the contralateral limb. Likewise, there was no evidence of a systemic effect on the bone strength in any mouse strain. We did, however, find a small systemic effect on aBMD in DBA/2 J and C3H/HeN mice. The present study shows that BTX-induced immobilization causes the greatest loss of cortical and trabecular bone in C57BL/6 J and DBA/2 J mice. A smaller loss of bone microstructure and fracture strength was seen in BALB/cJ mice, while the bone microstructure and fracture strength of C3H/HeN mice were markedly less affected. This indicates that BTX-induced loss of bone is mouse strain dependent. We found only minimal systemic

  8. Microstructure-grain orientation relationship in coarse grain nickel cold-rolled to large strain

    International Nuclear Information System (INIS)

    Chen, H.S.; Godfrey, A.; Hansen, N.; Xie, J.X.; Liu, Q.

    2008-01-01

    The relationship between crystallographic orientation and the deformation microstructure formed during cold-rolling to high strains (up to ε vM = 4.5) has been investigated. The starting material was Ni (99.96% purity) with a coarse initial average grain size (approximately 500 μm). Microstructural characterization was carried out using a combination of electron channeling contrast imaging and electron back-scatter diffraction orientation mapping. An orientation dependence of the deformation microstructure was observed even at the highest strain examined. A large increase in the average boundary misorientation is found at strains above ε vM = 1.8 for regions with the {1 1 2} and {1 2 3} orientations. This increase accompanies the structural transition from a medium strain microstructure to a high strain lamellar microstructure. In contrast, the average misorientation in regions of {1 1 0} orientation increases only slowly even up to the highest strain examined

  9. Investigation on seasonal variation of thermal-induced strain in flexible pavements based on field and laboratory measurements

    Directory of Open Access Journals (Sweden)

    Simita Biswas

    2016-09-01

    Full Text Available Pavement temperature variation has a large influence on the structural response of flexible pavements. Daily and seasonal temperature fluctuation causes expansion and contraction of pavement material, which then leads to the generation of thermal strain. In this study, field observation and laboratory tests were conducted to investigate seasonal variation of thermal-induced strain in flexible pavement. Field observations were conducted at the Integrated Road Research Facility (IRRF’s test road in Edmonton, Alberta, Canada, which is fully equipped with structural and environmental monitoring instruments. The main objective of the field study was to compare the variation of thermal-induced strain in warm and cold seasons. Field results indicated that thermal-induced strain is 1.4–2.0 times greater in cold seasons than in warm seasons following the same pavement temperature variations; however, strain generation rate was greater in warm seasons. Laboratory testing of asphalt slab and cylindrical samples produced comparable ratios. Moreover, field observation and laboratory testing showed a similar trend of temperature and thermal strain variations. Keywords: Thermal-induced strain, Asphalt strain gauge, Field observation, Flexible pavement, Laboratory testing, Seasonal variation

  10. Microstructure and micro-texture evolution during large strain deformation of aluminium alloy AA 2219

    Energy Technology Data Exchange (ETDEWEB)

    Murty, S.V.S. Narayana [Materials and Mechanical Entity, Vikram Sarabhai Space Center, Trivandrum-695 022 (India); Sarkar, Aditya [Department of Materials Science and Engineering, Indian Institute of Technology, Gandhinagar-382 424 (India); Narayanan, P. Ramesh; Venkitakrishnan, P.V. [Materials and Mechanical Entity, Vikram Sarabhai Space Center, Trivandrum-695 022 (India); Mukhopadhyay, J. [Department of Materials Science and Engineering, Indian Institute of Technology, Gandhinagar-382 424 (India)

    2016-11-20

    Aluminium alloy AA2219 is widely used in the fabrication of propellant tanks of cryogenic stages of satellite launch vehicles. These propellant tanks are welded structures and a fine grained microstructure is usually preferred for sheets/plates and ring rolled rings used in their fabrication. In order to study the effect of large strain deformation on the microstructural evolution, hot isothermal plane strain compression (PSC) tests were conducted on AA 2219 in the temperature range of 250 °C–400 °C and at strain rates of 0.01 s{sup −1} and 1 s{sup −1}. Flow curves obtained at different temperatures and strain rates exhibited two types of behavior; one with a clear stress peak followed by softening, occurring below Z=2.5E+15 and steady state flow behavior above it. Electron Back-Scatter Diffraction (EBSD) analysis of the PSC tested samples at the location of maximum strain revealed the presence of lamellar microstructures with very low fraction of transverse high angle boundaries (HABs). The loss of HABs during large strain deformation is attributed to the occurrence of dynamic recovery (DRV) as the ratio of calculated to measured lamellar boundary width is less than unity. Based on detailed microstructure and micro texture analysis, it was concluded that it is very difficult to obtain large fraction of HABs through uniaxial large strain deformation. Therefore, to obtain fine grain microstructure in thermo-mechanically processed AA2219 products, multi-axial deformation is essential.

  11. Aeromonas caviae strain induces Th1 cytokine response in mouse intestinal tract

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S L; Lye, D J; McKinstry, Craig A.; Vesper, Sephen J.

    2010-01-01

    Aeromonas caviae has been associated with human gastrointestinal disease. Strains of this species typically lack virulence factors (VFs) such as enterotoxins and hemolysins that are produced by other human pathogens of the Aeromonas genus. Microarray profiling of murine small intestinal extracts, 24 hours after oral infection with an A. caviae strain, provides evidence of a Th1 type immune response. A large number of gamma-interferon (γ-IFN) induced genes are up-regulated as well as several tumor necrosis factor-alpha (TNF-α) transcripts. A. caviae has always been considered as opportunistic pathogen because it lacks obvious virulence factors. This current effort suggests that an A. caviae strain can colonize the murine intestinal tract and cause what has been described by others as a dysregulatory cytokine response. This response could explain why a number of diarrheal waterborne disease cases have been attributed to A. caviae even though it lacks obvious enteropathogenic properties.

  12. Strain-induced topological quantum phase transition in phosphorene oxide

    Science.gov (United States)

    Kang, Seoung-Hun; Park, Jejune; Woo, Sungjong; Kwon, Young-Kyun

    Using ab initio density functional theory, we investigate the structural stability and electronic properties of phosphorene oxides (POx) with different oxygen compositions x. A variety of configurations are modeled and optimized geometrically to search for the equilibrium structure for each x value. Our electronic structure calculations on the equilibrium configuration obtained for each x reveal that the band gap tends to increase with the oxygen composition of x 0.5. We further explore the strain effect on the electronic structure of the fully oxidized phosphorene, PO, with x = 1. At a particular strain without spin-orbit coupling (SOC) is observed a band gap closure near the Γ point in the k space. We further find the strain in tandem with SOC induces an interesting band inversion with a reopened very small band gap (5 meV), and thus gives rise to a topological quantum phase transition from a normal insulator to a topological insulator. Such a topological phase transition is confirmed by the wave function analysis and the band topology identified by the Z2 invariant calculation.

  13. Large strain variable stiffness composites for shear deformations with applications to morphing aircraft skins

    Science.gov (United States)

    McKnight, G. P.; Henry, C. P.

    2008-03-01

    Morphing or reconfigurable structures potentially allow for previously unattainable vehicle performance by permitting several optimized structures to be achieved using a single platform. The key to enabling this technology in applications such as aircraft wings, nozzles, and control surfaces, are new engineered materials which can achieve the necessary deformations but limit losses in parasitic actuation mass and structural efficiency (stiffness/weight). These materials should exhibit precise control of deformation properties and provide high stiffness when exercised through large deformations. In this work, we build upon previous efforts in segmented reinforcement variable stiffness composites employing shape memory polymers to create prototype hybrid composite materials that combine the benefits of cellular materials with those of discontinuous reinforcement composites. These composites help overcome two key challenges for shearing wing skins: the resistance to out of plane buckling from actuation induced shear deformation, and resistance to membrane deflections resulting from distributed aerodynamic pressure loading. We designed, fabricated, and tested composite materials intended for shear deformation and address out of plane deflections in variable area wing skins. Our designs are based on the kinematic engineering of reinforcement platelets such that desired microstructural kinematics is achieved through prescribed boundary conditions. We achieve this kinematic control by etching sheets of metallic reinforcement into regular patterns of platelets and connecting ligaments. This kinematic engineering allows optimization of materials properties for a known deformation pathway. We use mechanical analysis and full field photogrammetry to relate local scale kinematics and strains to global deformations for both axial tension loading and shear loading with a pinned-diamond type fixture. The Poisson ratio of the kinematically engineered composite is ~3x higher than

  14. Substrate strain induced interaction of adatoms on W (110)

    Science.gov (United States)

    Kappus, W.

    1980-09-01

    The interaction of adatoms due to elastic strains created in an elastically isotropic substrate is investigated. For cases where the adatoms occupy sites with low symmetry, an angular dependent interaction results which falls off as s-3 at large distances. An exact expression is given for the long range interaction in terms of an anisotropy parameter of the force dipole tensor. The short range interaction is calculated by introducing a smooth cutoff. Interactions of adatoms on near neighbour sites on W (110) are given.

  15. 6% magnetic-field-induced strain by twin-boundary motion in ferromagnetic Ni-Mn-Ga

    International Nuclear Information System (INIS)

    Murray, S. J.; Marioni, M.; Allen, S. M.; O'Handley, R. C.; Lograsso, T. A.

    2000-01-01

    Field-induced strains of 6% are reported in ferromagnetic Ni-Mn-Ga martensites at room temperature. The strains are the result of twin boundary motion driven largely by the Zeeman energy difference across the twin boundary. The strain measured parallel to the applied magnetic field is negative in the sample/field geometry used here. The strain saturates in fields of order 400 kA/m and is blocked by a compressive stress of order 2 MPa applied orthogonal to the magnetic field. The strain versus field curves exhibit appreciable hysteresis associated with the motion of the twin boundaries. A simple model accounts quantitatively for the dependence of strain on magnetic field and external stress using as input parameters only measured quantities. (c) 2000 American Institute of Physics

  16. Strain-induced phenomenon in complex oxide thin films

    Science.gov (United States)

    Haislmaier, Ryan

    Complex oxide materials wield an immense spectrum of functional properties such as ferroelectricity, ferromagnetism, magnetoelectricity, optoelectricity, optomechanical, magnetoresistance, superconductivity, etc. The rich coupling between charge, spin, strain, and orbital degrees of freedom makes this material class extremely desirable and relevant for next generation electronic devices and technologies which are trending towards nanoscale dimensions. Development of complex oxide thin film materials is essential for realizing their integration into nanoscale electronic devices, where theoretically predicted multifunctional capabilities of oxides could add tremendous value. Employing thin film growth strategies such as epitaxial strain and heterostructure interface engineering can greatly enhance and even unlock novel material properties in complex oxides, which will be the main focus of this work. However, physically incorporating oxide materials into devices remains a challenge. While advancements in molecular beam epitaxy (MBE) of thin film oxide materials has led to the ability to grow oxide materials with atomic layer precision, there are still major limitations such as controlling stoichiometric compositions during growth as well as creating abrupt interfaces in multi-component layered oxide structures. The work done in this thesis addresses ways to overcome these limitations in order to harness intrinsic material phenomena. The development of adsorption-controlled stoichiometric growth windows of CaTiO3 and SrTiO3 thin film materials grown by hybrid MBE where Ti is supplied using metal-organic titanium tetraisopropoxide material is thoroughly outlined. These growth windows enable superior epitaxial strain-induced ferroelectric and dielectric properties to be accessed as demonstrated by chemical, structural, electrical, and optical characterization techniques. For tensile strained CaTiO3 and compressive strained SrTiO 3 films, the critical effects of

  17. Analysis of Large-Strain Extrusion Machining with Different Chip Compression Ratios

    Directory of Open Access Journals (Sweden)

    Wen Jun Deng

    2012-01-01

    Full Text Available Large-Strain Extrusion Machining (LSEM is a novel-introduced process for deforming materials to very high plastic strains to produce ultra-fine nanostructured materials. Before the technique can be exploited, it is important to understand the deformation behavior of the workpiece and its relationship to the machining parameters and friction conditions. This paper reports finite-element method (FEM analysis of the LSEM process to understand the evolution of temperature field, effective strain, and strain rate under different chip compression ratios. The cutting and thrust forces are also analyzed with respect to time. The results show that LSEM can produce very high strains by changing in the value of chip compression ratio, thereby enabling the production of nanostructured materials. The shape of the chip produced by LSEM can also be geometrically well constrained.

  18. Remarkable strain-induced magnetic anisotropy in epitaxial Co2MnGa (0 0 1) films

    International Nuclear Information System (INIS)

    Pechan, Michael J.; Yu, Chengtao; Carr, David; Palmstroem, Chris J.

    2005-01-01

    Remarkably large, strain-induced anisotropy is observed in the thin-film Heusler alloy Co 2 MnGa. 30 nm Co 2 MnGa (0 0 1) films have been epitaxially grown on different interlayers/substrates with varied strain, and investigated with ferromagnetic resonance. The film grown on ErAs/InGaAs/InP experiences tension strain, resulting in an out-of-plane strain-induced anisotropy (∼1.1x10 6 erg/cm 3 ) adding to the effects of shape anisotropy. In contrast, the film grown on ScErAs/GaAs, experiences a compression strain, resulting in an out-of-plane strain-induced anisotropy (∼3.3x10 6 erg/cm 3 ) which almost totally cancels the effects of shape anisotropy, thus rendering the film virtually isotropic. This results in the formation of stripe domains in remanence. In addition, small, but well-defined 2-fold and 4-fold in-plane anisotropy coexist in each sample with weak, but interesting strain dependence. Transport measurement shows small (<1%) magnetoresistance effects in the compression film, but negligible magnetoresistance in the relaxed and tension strained samples

  19. In situ measurement using FBGs of process-induced strains during curing of thick glass/epoxy laminate plate

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Hattel, Jesper Henri

    2012-01-01

    For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre...... Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary...... conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model...

  20. Mechanisms of large strain, high strain rate plastic flow in the explosively driven collapse of Ni-Al laminate cylinders

    International Nuclear Information System (INIS)

    Olney, K L; Chiu, P H; Nesterenko, V F; Higgins, A; Serge, M; Weihs, T P; Fritz, G; Stover, A; Benson, D J

    2014-01-01

    Ni-Al laminates have shown promise as reactive materials due to their high energy release through intermetallic reaction. In addition to the traditional ignition methods, the reaction may be initiated in hot spots that can be created during mechanical loading. The explosively driven thick walled cylinder (TWC) technique was performed on two Ni-Al laminates composed of thin foil layers with different mesostructues: concentric and corrugated. These experiments were conducted to examine how these materials accommodate large plastic strain under high strain rates. Finite element simulations of these specimens with mesostuctures digitized from the experimental samples were conducted to provide insight into the mesoscale mechanisms of plastic flow. The dependence of dynamic behaviour on mesostructure may be used to tailor the hot spot formation and therefore the reactivity of the material system.

  1. Fabrication and evaluation of hybrid silica/polymer optical fiber sensors for large strain measurement

    Science.gov (United States)

    Huang, Haiying

    2007-04-01

    Silica-based optical fiber sensors are widely used in structural health monitoring systems for strain and deflection measurement. One drawback of silica-based optical fiber sensors is their low strain toughness. In general, silica-based optical fiber sensors can only reliably measure strains up to 2%. Recently, polymer optical fiber sensors have been employed to measure large strain and deflection. Due to their high optical losses, the length of the polymer optical fibers is limited to 100 meters. In this paper, we present a novel economical technique to fabricate hybrid silica/polymer optical fiber strain sensors for large strain measurement. First, stress analysis of a surface-mounted optical fiber sensor is performed to understand the load distribution between the host structure and the optical fiber in relation to their mechanical properties. Next, the procedure of fabricating a polymer sensing element between two optical fibers is explained. The experimental set-up and the components used in the fabrication process are described in details. Mechanical testing results of the fabricated silica/polymer optical fiber strain sensor are presented.

  2. Application of large strain analysis for estimation of behavior and stability of rock mass

    International Nuclear Information System (INIS)

    Nakagawa, Mitsuo; Jiang, Yujing; Esaki, Tetsuro.

    1997-01-01

    It is difficult to simulate a large deformation phenomena with plastic flow after failure by using a general numerical approach, such as the FEM (finite element method), based on the infinitesimal strain theory. In order to investigate the behavior of tunnels excavated in soft rock mass, a new simulation technique which can represent large strain accurately is desired, and the code FLAC (Fast Lagragian Analysis of Continua) adopted in this study is being thought a best mean for this propose. In this paper, the basic principles and the application of the large strain analysis method to stability analysis and prediction of the deformational behavior of tunnels in soft rock are presented. First, the features of the large strain theory and some different points from the infinitesimal strain theory are made up. Next, as the examples, the reproduction of uniaxial compression test for soft rock material and the stability analysis of tunnel in soft rock are tried so as to determine the capability of presenting the large deformational behavior. (author)

  3. Strain Dependent Genetic Networks for Antibiotic-Sensitivity in a Bacterial Pathogen with a Large Pan-Genome.

    Directory of Open Access Journals (Sweden)

    Tim van Opijnen

    2016-09-01

    Full Text Available The interaction between an antibiotic and bacterium is not merely restricted to the drug and its direct target, rather antibiotic induced stress seems to resonate through the bacterium, creating selective pressures that drive the emergence of adaptive mutations not only in the direct target, but in genes involved in many different fundamental processes as well. Surprisingly, it has been shown that adaptive mutations do not necessarily have the same effect in all species, indicating that the genetic background influences how phenotypes are manifested. However, to what extent the genetic background affects the manner in which a bacterium experiences antibiotic stress, and how this stress is processed is unclear. Here we employ the genome-wide tool Tn-Seq to construct daptomycin-sensitivity profiles for two strains of the bacterial pathogen Streptococcus pneumoniae. Remarkably, over half of the genes that are important for dealing with antibiotic-induced stress in one strain are dispensable in another. By confirming over 100 genotype-phenotype relationships, probing potassium-loss, employing genetic interaction mapping as well as temporal gene-expression experiments we reveal genome-wide conditionally important/essential genes, we discover roles for genes with unknown function, and uncover parts of the antibiotic's mode-of-action. Moreover, by mapping the underlying genomic network for two query genes we encounter little conservation in network connectivity between strains as well as profound differences in regulatory relationships. Our approach uniquely enables genome-wide fitness comparisons across strains, facilitating the discovery that antibiotic responses are complex events that can vary widely between strains, which suggests that in some cases the emergence of resistance could be strain specific and at least for species with a large pan-genome less predictable.

  4. Understanding Strain-Induced Phase Transformations in BiFeO3 Thin Films.

    Science.gov (United States)

    Dixit, Hemant; Beekman, Christianne; Schlepütz, Christian M; Siemons, Wolter; Yang, Yongsoo; Senabulya, Nancy; Clarke, Roy; Chi, Miaofang; Christen, Hans M; Cooper, Valentino R

    2015-08-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO 3 thin films, which comprises a tetragonal-like ( T ') and an intermediate S ' polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T ' phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S ' phase is energetically very close to the T ' phase, but is structurally similar to the bulk rhombohedral ( R ) phase. By fully characterizing the intermediate S ' polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T ' and S ' phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S ' and T ' polymorphs, which have very different octahedral rotation patterns and c / a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO 3 films. Additionally, a blueshift in the band gap when moving from R to S ' to T ' is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

  5. Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

    Directory of Open Access Journals (Sweden)

    Xijia Gu

    2010-08-01

    Full Text Available We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.

  6. Microwave interrogated large core fused silica fiber Michelson interferometer for strain sensing.

    Science.gov (United States)

    Hua, Liwei; Song, Yang; Huang, Jie; Lan, Xinwei; Li, Yanjun; Xiao, Hai

    2015-08-20

    A Michelson-type large core optical fiber sensor has been developed, which is designed based on the optical carrier-based microwave interferometry technique, and fabricated by using two pieces of 200-μm diameter fused silica core fiber as two arms of the Michelson interferometer. The interference fringe pattern caused by the optical path difference of the two arms is interrogated in the microwave domain, where the fringe visibility of 40 dB has easily been obtained. The strain sensing at both room temperature and high temperatures has been demonstrated by using such a sensor. Experimental results show that this sensor has a linear response to the applied strain, and also has relatively low temperature-strain cross talk. The dopant-free quality of the fused silica fiber provides high possibility for the sensor to have promising strain sensing performance in a high temperature environment.

  7. Large strain deformation behavior of polymeric gels in shear- and cavitation rheology

    Science.gov (United States)

    Hashemnejad, Seyed Meysam; Kundu, Santanu

    Polymeric gels are used in many applications including in biomedical and in food industries. Investigation of mechanical responses of swollen polymer gels and linking that to the polymer chain dynamics are of significant interest. Here, large strain deformation behavior of two different gel systems and with different network architecture will be presented. We consider biologically relevant polysaccharide hydrogels, formed through ionic and covalent crosslinking, and physically associating triblock copolymer gels in a midblock selective solvent. Gels with similar low-strain shear modulus display distinctly different non-linear rheological behavior in large strain shear deformation. Both these gels display strain-stiffening behavior in shear-deformation prior to macroscopic fracture of the network, however, only the alginate gels display negative normal stress. The cavitation rheology data show that the critical pressure for cavitation is higher for alginate gels than that observed for triblock gels. These distinctly different large-strain deformation behavior has been related to the gel network structure, as alginate chains are much stiffer than the triblock polymer chains.

  8. Entanglement transitions induced by large deviations

    Science.gov (United States)

    Bhosale, Udaysinh T.

    2017-12-01

    The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B , is computed analytically using a Coulomb gas method. It is shown that this probability, for large N , goes as exp[-β N2Φ (ζ ) ] , where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ (ζ ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A , using the properties of the density matrix's partial transpose ρ12Γ. The density of states of ρ12Γ is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ . Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.

  9. Total synthesis and related studies of large, strained, and bioactive natural products

    Science.gov (United States)

    HIRAMA, Masahiro

    2016-01-01

    Our chemical syntheses and related scientific investigations of natural products with complex architectures and powerful biological activities are described, focusing on the very large 3 nm-long polycyclic ethers called the ciguatoxins, highly strained and labile chromoprotein antitumor antibiotics featuring nine-membered enediyne cores, and extremely potent anthelmintic macrolides called the avermectins. PMID:27725470

  10. Numerical simulation of elasto-plastic electro-osmosis consolidation at large strain

    NARCIS (Netherlands)

    Yuan, J.; Hicks, M.A.

    2015-01-01

    n this paper, a numerical solution for the electro-osmosis consolidation of clay in multi-dimensional domains at large strains is presented, with the coupling of the soil mechanical behaviour, pore water transport and electrical fields being considered. In particular, the Modified Cam Clay model is

  11. Corrosion induced strain monitoring through fibre optic sensors

    International Nuclear Information System (INIS)

    Grattan, S K T; Basheer, P A M; Taylor, S E; Zhao, W; Sun, T; Grattan, K T V

    2007-01-01

    The use of strain sensors is commonplace within civil engineering. Fibre optic strain sensors offer a number of advantages over the current electrical resistance type gauges. In this paper the use of fibre optic strain sensors and electrical resistance gauges to monitor the production of corrosion by-products has been investigated and reported

  12. Experimental validation of finite element analysis of human vertebral collapse under large compressive strains.

    Science.gov (United States)

    Hosseini, Hadi S; Clouthier, Allison L; Zysset, Philippe K

    2014-04-01

    Osteoporosis-related vertebral fractures represent a major health problem in elderly populations. Such fractures can often only be diagnosed after a substantial deformation history of the vertebral body. Therefore, it remains a challenge for clinicians to distinguish between stable and progressive potentially harmful fractures. Accordingly, novel criteria for selection of the appropriate conservative or surgical treatment are urgently needed. Computer tomography-based finite element analysis is an increasingly accepted method to predict the quasi-static vertebral strength and to follow up this small strain property longitudinally in time. A recent development in constitutive modeling allows us to simulate strain localization and densification in trabecular bone under large compressive strains without mesh dependence. The aim of this work was to validate this recently developed constitutive model of trabecular bone for the prediction of strain localization and densification in the human vertebral body subjected to large compressive deformation. A custom-made stepwise loading device mounted in a high resolution peripheral computer tomography system was used to describe the progressive collapse of 13 human vertebrae under axial compression. Continuum finite element analyses of the 13 compression tests were realized and the zones of high volumetric strain were compared with the experiments. A fair qualitative correspondence of the strain localization zone between the experiment and finite element analysis was achieved in 9 out of 13 tests and significant correlations of the volumetric strains were obtained throughout the range of applied axial compression. Interestingly, the stepwise propagating localization zones in trabecular bone converged to the buckling locations in the cortical shell. While the adopted continuum finite element approach still suffers from several limitations, these encouraging preliminary results towards the prediction of extended vertebral

  13. The effects of strain induced martensite on stress corrosion cracking in AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Lee, W. S.; Kwon, S. I.

    1989-01-01

    The effects of strain induced martensite on stress corrosion cracking behavior in AISI 304 stainless steel in boiling 42 wt% MgCl 2 solution were investigated using monotonic SSRT and cyclic SSRT with R=0.1 stress ratio. As the amount of pre-strain increased, the failure time of the specimens in monotonic SSRT test decreased independent of the existence of strain induced martensite. The strain induced martensite seems to promote the crack initiation but to retard the crack propagation during stress corrosion cracking

  14. Strain-Based Design Methodology of Large Diameter Grade X80 Linepipe

    Energy Technology Data Exchange (ETDEWEB)

    Lower, Mark D. [ORNL

    2014-04-01

    Continuous growth in energy demand is driving oil and natural gas production to areas that are often located far from major markets where the terrain is prone to earthquakes, landslides, and other types of ground motion. Transmission pipelines that cross this type of terrain can experience large longitudinal strains and plastic circumferential elongation as the pipeline experiences alignment changes resulting from differential ground movement. Such displacements can potentially impact pipeline safety by adversely affecting structural capacity and leak tight integrity of the linepipe steel. Planning for new long-distance transmission pipelines usually involves consideration of higher strength linepipe steels because their use allows pipeline operators to reduce the overall cost of pipeline construction and increase pipeline throughput by increasing the operating pressure. The design trend for new pipelines in areas prone to ground movement has evolved over the last 10 years from a stress-based design approach to a strain-based design (SBD) approach to further realize the cost benefits from using higher strength linepipe steels. This report presents an overview of SBD for pipelines subjected to large longitudinal strain and high internal pressure with emphasis on the tensile strain capacity of high-strength microalloyed linepipe steel. The technical basis for this report involved engineering analysis and examination of the mechanical behavior of Grade X80 linepipe steel in both the longitudinal and circumferential directions. Testing was conducted to assess effects on material processing including as-rolled, expanded, and heat treatment processing intended to simulate coating application. Elastic-plastic and low-cycle fatigue analyses were also performed with varying internal pressures. Proposed SBD models discussed in this report are based on classical plasticity theory and account for material anisotropy, triaxial strain, and microstructural damage effects

  15. Inhomogeneous strain induced by fast neutron irradiation in NaKSO/sub 4/ crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kandil, S.H.; Kassem, M.E.; El-Khatib, A.; El-Gamal, M.A.; El-Wahidy, E.F.

    1987-11-01

    The paper reports the effect of fast neutron irradiation on the thermal properties of NaKSO/sub 4/ crystals in the temperature range 400-475 K. Results are presented for the thermal expansion, tensile strain and specific heat of NaKSO/sub 4/, as a function of neutron irradiation dose. All these results revealed an inhomogeneous strain induced by the radiation. It is suggested that this induced inhomogeneous strain could be used to detect neutron exposure doses.

  16. Inhomogeneous strain induced by fast neutron irradiation in NaKSO4 crystals

    International Nuclear Information System (INIS)

    Kandil, S.H.; Kassem, M.E.; El-Khatib, A.; El-Gamal, M.A.; El-Wahidy, E.F.

    1987-01-01

    The paper reports the effect of fast neutron irradiation on the thermal properties of NaKSO 4 crystals in the temperature range 400-475 K. Results are presented for the thermal expansion, tensile strain and specific heat of NaKSO 4 , as a function of neutron irradiation dose. All these results revealed an inhomogeneous strain induced by the radiation. It is suggested that this induced inhomogeneous strain could be used to detect neutron exposure doses. (UK)

  17. High resolution electron back-scatter diffraction analysis of thermally and mechanically induced strains near carbide inclusions in a superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Karamched, Phani S., E-mail: phani.karamched@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2011-01-15

    Cross-correlation-based analysis of electron back-scatter diffraction (EBSD) patterns has been used to obtain high angular resolution maps of lattice rotations and elastic strains near carbides in a directionally solidified superalloy MAR-M-002. Lattice curvatures were determined from the EBSD measurements and used to estimate the distribution of geometrically necessary dislocations (GNDs) induced by the deformation. Significant strains were induced by thermal treatment due to the lower thermal expansion coefficient of the carbide inclusions compared to that of the matrix. In addition to elastic strains the mismatch was sufficient to have induced localized plastic deformation in the matrix leading to a GND density of 3 x 10{sup 13} m{sup -2} in regions around the carbide. Three-point bending was then used to impose strain levels within the range {+-}12% across the height of the bend bar. EBSD lattice curvature measurements were then made at both carbide-containing and carbide-free regions at different heights across the bar. The average GND density increases with the magnitude of the imposed strain (both in tension and compression), and is markedly higher near the carbides particles. The higher GND densities near the carbides (order of 10{sup 14} m{sup -2}) are generated by the large strain gradients produced around the plastically rigid inclusion during mechanical deformation with some minor contribution from the pre-existing residual deformation caused by the thermal mismatch between carbide and nickel matrix.

  18. Large pericardial effusion induced by minoxidil.

    Science.gov (United States)

    Çilingiroğlu, Mehmet; Akkuş, Nuri; Sethi, Salil; Modi, Kalgi A

    2012-04-01

    A 53-year-old male admitted with increased shortness of breath. In the physical examination, he had dyspnea, tachycardia and tachypnea. An echocardiogram showed large pericardial effusion (PE) as well as significant pulmonary hypertension. He had been started recently on minoxidil for blood pressure control. PE was reported to occur with minoxidil treatment both in patients undergoing dialysis and those with normal renal function. Pulmonary hypertension has been reported to affect the cardiac tamponade physiology. Because of significant pulmonary hypertension in our patient, a right heart catheterization was also done, which prevented cardiac tamponade. He was treated conservatively without any intervention, and PE resolved spontaneously after discontinuation of minoxidil.

  19. Effects of strain and strain-induced α′-martensite on passive films in AISI 304 austenitic stainless steel

    International Nuclear Information System (INIS)

    Lv, Jinlong; Luo, Hongyun

    2014-01-01

    In this paper, the effects of strain and heat treatment on strain-induced α′-martensite of AISI 304 stainless steel tubes were measured by X-ray diffraction. Moreover, the effects of strain and content of α′-martensite on passivated property on the surface of the material in borate buffer solution were evaluated by electrochemical technique. The results showed that the volume fraction of α′-martensite increased gradually with the increase of tensile strain for as-received and solid solution samples. However, α′-martensite in as-received sample was more than that in the solid solution sample. The electrochemical impedance spectroscopy results showed that the solid solution treatment improved corrosion resistance of the steel, especially for samples with small strain. Moreover, acceptor densities were always higher than donor densities for as-received and solid solution samples. With the increase of strain, the increase tendency of acceptor density was more significant than that of donor density. We also found that the total density of the acceptor and donor almost increased linearly with the increase of α′-martensite. The present results indicated that the increased acceptor density might lead to the decreased corrosion resistance of the steel. - Highlights: • The solid solution treatment improved corrosion resistance of the stainless steel. • The deteriorated passivated property after strain could be attributed to the increased acceptor density. • The α′-martensite reduced corrosion resistance of the stainless steel

  20. Measurement of earthquake-induced shear strain in sandy gravel

    International Nuclear Information System (INIS)

    Ohkawa, I.; Futaki, M.; Yamanouchi, H.

    1989-01-01

    The nuclear power reactor buildings have been constructed on the hard rock ground formed in or before the Tertiary in Japan. This is mainly because the nuclear reactor building is much heavier than the common buildings and requires a large bearing capacity of the underlying soil deposit, and additionally the excessive deformation in soil deposit might cause damage in reactor building and subsequently cause the malfunction of the internal important facilities. Another reason is that the Quaternary soil deposit is not fully known with respect to its dynamic property. The gravel, and the sandy gravel, the representative soils of the Quaternary, have been believed to be suitable soil deposits to support the foundation of a common building, although the soils have rarely been investigated so closely on their physical properties quantitatively. In this paper, the dynamic deformability, i.e., the shear stress-strain relationship of the Quaternary diluvial soil deposit is examined through the earthquake ground motion measurement using accelerometers, pore-pressure meters, the specific devices developed in this research work. The objective soil deposit in this research is the sandy gravel of the diluvial and the alluvial

  1. Quasi real-time estimation of the moment magnitude of large earthquake from static strain changes

    Science.gov (United States)

    Itaba, S.

    2016-12-01

    The 2011 Tohoku-Oki (off the Pacific coast of Tohoku) earthquake, of moment magnitude 9.0, was accompanied by large static strain changes (10-7), as measured by borehole strainmeters operated by the Geological Survey of Japan in the Tokai, Kii Peninsula, and Shikoku regions. A fault model for the earthquake on the boundary between the Pacific and North American plates, based on these borehole strainmeter data, yielded a moment magnitude of 8.7. On the other hand, based on the seismic wave, the prompt report of the magnitude which the Japan Meteorological Agency (JMA) announced just after earthquake occurrence was 7.9. Such geodetic moment magnitudes, derived from static strain changes, can be estimated almost as rapidly as determinations using seismic waves. I have to verify the validity of this method in some cases. In the case of this earthquake's largest aftershock, which occurred 29 minutes after the mainshock. The prompt report issued by JMA assigned this aftershock a magnitude of 7.3, whereas the moment magnitude derived from borehole strain data is 7.6, which is much closer to the actual moment magnitude of 7.7. In order to grasp the magnitude of a great earthquake earlier, several methods are now being suggested to reduce the earthquake disasters including tsunami. Our simple method of using static strain changes is one of the strong methods for rapid estimation of the magnitude of large earthquakes, and useful to improve the accuracy of Earthquake Early Warning.

  2. Strain-induced properties of epitaxial VOx thin films

    NARCIS (Netherlands)

    Rata, AD; Hibma, T

    We have grown VOx thin films on different substrates in order to investigate the influence of epitaxial strain on the transport properties. We found that the electric conductivity is much larger for films grown under compressive strain on SrTiO3 substrates, as compared to bulk material and VOx films

  3. In situ study of annealing-induced strain relaxation in diamond nanoparticles using Bragg coherent diffraction imaging

    Directory of Open Access Journals (Sweden)

    S. O. Hruszkewycz

    2017-02-01

    Full Text Available We observed changes in morphology and internal strain state of commercial diamond nanocrystals during high-temperature annealing. Three nanodiamonds were measured with Bragg coherent x-ray diffraction imaging, yielding three-dimensional strain-sensitive images as a function of time/temperature. Up to temperatures of 800 °C, crystals with Gaussian strain distributions with a full-width-at-half-maximum of less than 8×10−4 were largely unchanged, and annealing-induced strain relaxation was observed in a nanodiamond with maximum lattice distortions above this threshold. X-ray measurements found changes in nanodiamond morphology at temperatures above 600 °C that are consistent with graphitization of the surface, a result verified with ensemble Raman measurements.

  4. Strain-induced friction anisotropy between graphene and molecular liquids

    Science.gov (United States)

    Liao, Meng; To, Quy-Dong; Léonard, Céline; Monchiet, Vincent; Vo, Van-Hoang

    2017-01-01

    In this paper, we study the friction behavior of molecular liquids with anisotropically strained graphene. Due to the changes of lattice and the potential energy surface, the friction is orientation dependent and can be computed by tensorial Green-Kubo formula. Simple quantitative estimations are also proposed for the zero-time response and agree reasonably well with the molecular dynamics results. From simulations, we can obtain the information of structures, dynamics of the system, and study the influence of strain and molecular shapes on the anisotropy degree. It is found that unilateral strain can increase friction in all directions but the strain direction is privileged. Numerical evidences also show that nonspherical molecules are more sensitive to strain and give rise to more pronounced anisotropy effects.

  5. A large-strain radial consolidation theory for soft clays improved by vertical drains

    OpenAIRE

    Geng, X; Yu, H-S

    2017-01-01

    A system of vertical drains with combined vacuum and surcharge preloading is an effective solution for promoting radial flow, accelerating consolidation. However, when a mixture of soil and water is deposited at a low initial density, a significant amount of deformation or surface settlement occurs. Therefore, it is necessary to introduce large-strain theory, which has been widely used to manage dredged disposal sites in one-dimensional theory, into radial consolidation theory. A governing eq...

  6. A large strain radial consolidation theory for soft clays improved by vertical drains\\ud

    OpenAIRE

    Geng, Xueyu; Yu, Hai-sui

    2017-01-01

    A system of vertical drains with combined vacuum and surcharge preloading is an effective 10 solution for promoting radial flow, accelerating consolidation. However, when a mixture of soil and\\ud 11 water is deposited at a low initial density, a significant amount of deformation or surface settlement 12 occurs. Therefore, it is necessary to introduce large strain theory, which has been widely used to manage\\ud 13 dredged disposal sites in one-dimensional theory, into radial consolidation theo...

  7. Micromagnetic Simulation of Strain-Assisted Current-Induced Magnetization Switching

    Directory of Open Access Journals (Sweden)

    H. B. Huang

    2016-01-01

    Full Text Available We investigated the effect of substrate misfit strain on the current-induced magnetization switching in magnetic tunnel junctions by combining micromagnetic simulation with phase-field microelasticity theory. Our results indicate that the positive substrate misfit strain can decrease the critical current density of magnetization switching by pushing the magnetization from out-of-plane to in-plane directions, while the negative strain pushes the magnetization back to the out-of-plane directions. The magnetic domain evolution is obtained to demonstrate the strain-assisted current-induced magnetization switching.

  8. Low cycle fatigue strength of austenitic stainless steel under large strain regime

    International Nuclear Information System (INIS)

    Sakai, Michiya; Saito, Kiyoshi; Matsuura, Shinichi

    1998-01-01

    In order to establish realistic seismic safety of nuclear power plants, it is necessary to clarify the failure mode of each components and prepare a damage evaluation method. The authors have proposed the damage evaluation method based on the fully numerical approach to evaluate the low cycle fatigue (LCF) failure under seismic loadings. This method has been validated by comparison with the dynamic failure tests of thin elbows which should be the one of the important components of the FBR primary piping system. However, since there exists limited LCF data, fatigue lives under large strain regime have been extrapolated by available fatigue data. In this study, LCF tests have been conducted over a large strain range from 2% to 10% on austenitic stainless steel SUS304. From the results, the regressive LCF curve has been proposed to modify the Wada's best-fit LCF curve under large strain regime. The usage factors calculated by author's numerical approach using proposed LCF curve have been improved to correct the underestimation of the fatigue damage. (author)

  9. Stability of surface plastic flow in large strain deformation of metals

    Science.gov (United States)

    Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

    We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

  10. Cerium-144-induced lung gumors in two strains of mice

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, F.F.; Griffith, W.C.

    1995-12-01

    A major problem in the extrapolation of radiation cancer risk factors from one species or population to another is the choice of the risk model to use, either absolute or relative. The purpose of this study was to compare absolute and relative risk models in predicting the lung-tumor risks between a low lung-tumor incidence strain of mice and a high-incidence strain of mice. The conclusion from this study is that absolute risk is more accurate than relative risk for predicting lung tumor risk from high to low lung-tumor incidence strains of mice.

  11. Strain-induced internal fibrillation in looped aramid filaments

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell

    2010-01-01

    in the scattering pattern is observed. One model capable of describing the intensity is a model of stacked cylinders. These cylinders could be part of the fibrillar structure present in the PPTA fibres, which consist of cylinder- to tape-like objects, the presence of which is supported by SEM images. One...... hypothetical physical interpretation presented here for the appearance of a regular internal structure is the occurrence of fibrillar separation in regions undergoing axially compressive strain, and the appearance of strain relief/slip planes between packs of fibrils in regions undergoing tensile strain...

  12. Tuning martensitic transformation, large magnetoresistance and strain in Ni50-xFexMn36Sn14 Heusler alloys

    Science.gov (United States)

    Liao, Pan; Jing, Chao; Zheng, Dong; Li, Zhe; Kang, Baojuan; Deng, Dongmei; Cao, Shixun; Lu, Bo; Zhang, Jincang

    2015-09-01

    We have investigated the martensitic transformation, exchange bias, magnetoresistance (MR) and strain in Ni50-xFexMn36Sn14 (x=1, 2, 3, 4) Heusler alloys. With the increase of Fe content, the austenite phase could be stabilized with L21 structure and hence the martensitic transition shifts to a lower temperature and finally disappears. This behavior can be understood by the weakening of Ni-Mn hybridization to suppress AFM interactions and enhancement of Fe-Fe ferromagnetic exchange interactions. The same reason can account for the slight decrease of exchange bias field (HEB) with the increase of the Fe content from x=1 to 2 and the disappearance of HEB for x=3. We observed MR effect for x=3, and a maximum MR value of -52% was achieved, which can be explained by the change in the electronic structure during martensitic transformation induced by the magnetic field. In addition, a large strain of 0.207% in Ni49Fe1Mn36Sn14 was observed due to the changes of lattice parameters during the martensitic transformation induced by temperature.

  13. Soft network materials with isotropic negative Poisson's ratios over large strains.

    Science.gov (United States)

    Liu, Jianxing; Zhang, Yihui

    2018-01-31

    Auxetic materials with negative Poisson's ratios have important applications across a broad range of engineering areas, such as biomedical devices, aerospace engineering and automotive engineering. A variety of design strategies have been developed to achieve artificial auxetic materials with controllable responses in the Poisson's ratio. The development of designs that can offer isotropic negative Poisson's ratios over large strains can open up new opportunities in emerging biomedical applications, which, however, remains a challenge. Here, we introduce deterministic routes to soft architected materials that can be tailored precisely to yield the values of Poisson's ratio in the range from -1 to 1, in an isotropic manner, with a tunable strain range from 0% to ∼90%. The designs rely on a network construction in a periodic lattice topology, which incorporates zigzag microstructures as building blocks to connect lattice nodes. Combined experimental and theoretical studies on broad classes of network topologies illustrate the wide-ranging utility of these concepts. Quantitative mechanics modeling under both infinitesimal and finite deformations allows the development of a rigorous design algorithm that determines the necessary network geometries to yield target Poisson ratios over desired strain ranges. Demonstrative examples in artificial skin with both the negative Poisson's ratio and the nonlinear stress-strain curve precisely matching those of the cat's skin and in unusual cylindrical structures with engineered Poisson effect and shape memory effect suggest potential applications of these network materials.

  14. External-strain-induced semimetallic and metallic phase of chlorographene

    Science.gov (United States)

    Puri, Shivam; Bhowmick, Somnath

    2018-04-01

    To overcome the limitations of graphene due to lack of intrinsic band gap, it is generally functionalized with hydrogen or halogen atoms such as fluorine and chlorine. Generally, such functionalization yields a moderate- to high-band-gap material in case of 100% coverage, for example ≈1.5 eV in graphene functionalized with chlorine atoms or chlorographene. In this paper, using ab initio calculations, we report very interesting transformations observed in chlorographene under external strain, driving it to a state with nearly vanishing band gap (under tensile strain) and even converting it to a metal (under compressive strain). We also show the importance of spin-orbit coupling, responsible for the few meV band gap of chlorographene observed under high tensile strain, which would have been a gapless semimetal otherwise.

  15. Enhanced thermo-mechanical performance and strain-induced ...

    Indian Academy of Sciences (India)

    gap compared with pure TiO2, which can be attributed to the strain within the nanocomposite, thereby affecting .... TGA is an analytical technique used to determine the thermal ..... Program through the National Research Foundation of.

  16. Strain induced novel quantum magnetotransport properties of topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ning, E-mail: maning@stu.xjtu.edu.cn [Department of Physics, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, Shengli, E-mail: zhangsl@mail.xjtu.edu.cn [Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi’an 710049 (China); Liu, Daqing, E-mail: liudq@cczu.edu.cn [School of Mathematics and Physics, Changzhou University, Changzhou 213164 (China)

    2016-12-15

    Recent theoretical and experimental researches have revealed that the strained bulk HgTe can be regarded as a three-dimensional topological insulator (TI). Motivated by this, we explore the strain effects on the transport properties of the HgTe surface states, which are modulated by a weak 1D in-plane electrostatic periodic potential in the presence of a perpendicular magnetic field. We analytically derive the zero frequency (dc) diffusion conductivity for the case of quasielastic scattering in the Kubo formalism, and find that, in strong magnetic field regime, the Shubnikov–de Haas oscillations are superimposed on top of the Weiss oscillations due to the electric modulation for null and finite strain. Furthermore, the strain is shown to remove the degeneracy in inversion symmetric Dirac cones on the top and bottom surfaces. This accordingly gives rise to the splitting and mixture of Landau levels, and the asymmetric spectrum of the dc conductivity. These phenomena, not known in a conventional 2D electron gas and even in a strainless TI and graphene, are a consequence of the anomalous spectrum of surface states in a fully stained TI. These results should be valuable for electronic and spintronic applications of TIs, and thus we fully expect to see them in the further experiment. - Highlights: • The strain removes the degeneracy in inversion symmetric Dirac cones. • The strain gives rise to the splitting and mixture of the Landau levels. • The strain leads to the asymmetric spectrum of the dc conductivity. • Shubnikov de Haas oscillations are shown to be superimposed on Weiss oscillations. • Interplay between strain and electric field causes different occupancy of TI states.

  17. The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

    Science.gov (United States)

    Cios, G.; Tokarski, T.; Żywczak, A.; Dziurka, R.; Stępień, M.; Gondek, Ł.; Marciszko, M.; Pawłowski, B.; Wieczerzak, K.; Bała, P.

    2017-10-01

    This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (-60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to 70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α' → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov-Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

  18. Plastic Strain Induced Damage Evolution and Martensitic Transformation in Ductile Materials at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behaviour at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of thes...

  19. Modification of γ-induced mutagenesis in Ames test-strains

    International Nuclear Information System (INIS)

    Basha, S.G.; Krasavin, E.A.; Kozubek, S.; Amirtaev, K.G.

    1990-01-01

    Glycerine and cysteamine protective effect on mutagenesis was studied in 3 strains of Salmonella typhimurium under γ-radiation. Glycerine modifying effect was shown to be not similar for various test-strains and depended on DNA injury nature. DNA complex injuries were shown to play significant role in mutagenesis of TA100 and TA102 strains. Absence of cysteamine modifying effect on γ-induced mutagenesis testified to cysteamine effect on enzyme balance. 20 refs.; 2 figs.; 1 tab

  20. Electric Field Induced Strain in Electrostrictive Polymers Under High Hydrostatic Pressure - System Development and Material Characterization

    National Research Council Canada - National Science Library

    Zhang, Q

    2000-01-01

    ... of (i) developing a high performance piezo-bimorph based dilatometer which can be used to characterize the electric field induced strain response in polymer films under high hydrostatic pressure, (ii...

  1. Strain-induced modulation of near-field radiative transfer.

    Science.gov (United States)

    Ghanekar, Alok; Ricci, Matthew; Tian, Yanpei; Gregory, Otto; Zheng, Yi

    2018-06-11

    In this theoretical study, we present a near-field thermal modulator that exhibits change in radiative heat transfer when subjected to mechanical stress/strain. The device has two terminals at different temperatures separated by vacuum: one fixed and one stretchable. The stretchable side contains one-dimensional grating. When subjected to mechanical strain, the effective optical properties of the stretchable side are affected upon deformation of the grating. This results in modulation of surface waves across the interfaces influencing near-field radiative heat transfer. We show that for a separation of 100 nm, it is possible to achieve 25% change in radiative heat transfer for a strain of 10%.

  2. Cell culture isolation and sequence analysis of genetically diverse US porcine epidemic diarrhea virus strains including a novel strain with a large deletion in the spike gene.

    Science.gov (United States)

    Oka, Tomoichiro; Saif, Linda J; Marthaler, Douglas; Esseili, Malak A; Meulia, Tea; Lin, Chun-Ming; Vlasova, Anastasia N; Jung, Kwonil; Zhang, Yan; Wang, Qiuhong

    2014-10-10

    The highly contagious and deadly porcine epidemic diarrhea virus (PEDV) first appeared in the US in April 2013. Since then the virus has spread rapidly nationwide and to Canada and Mexico causing high mortality among nursing piglets and significant economic losses. Currently there are no efficacious preventive measures or therapeutic tools to control PEDV in the US. The isolation of PEDV in cell culture is the first step toward the development of an attenuated vaccine, to study the biology of PEDV and to develop in vitro PEDV immunoassays, inactivation assays and screen for PEDV antivirals. In this study, nine of 88 US PEDV strains were isolated successfully on Vero cells with supplemental trypsin and subjected to genomic sequence analysis. They differed genetically mainly in the N-terminal S protein region as follows: (1) strains (n=7) similar to the highly virulent US PEDV strains; (2) one similar to the reportedly US S INDEL PEDV strain; and (3) one novel strain most closely related to highly virulent US PEDV strains, but with a large (197aa) deletion in the S protein. Representative strains of these three genetic groups were passaged serially and grew to titers of ∼5-6log10 plaque forming units/mL. To our knowledge, this is the first report of the isolation in cell culture of an S INDEL PEDV strain and a PEDV strain with a large (197aa) deletion in the S protein. We also designed primer sets to detect these genetically diverse US PEDV strains. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Stepwise transformation behavior of the strain-induced martensitic transformation in a metastable stainless steel

    International Nuclear Information System (INIS)

    Hedstroem, Peter; Lienert, Ulrich; Almer, Jon; Oden, Magnus

    2007-01-01

    In situ high-energy X-ray diffraction during tensile loading has been used to investigate the evolution of lattice strains and the accompanying strain-induced martensitic transformation in cold-rolled sheets of a metastable stainless steel. At high applied strains the transformation to α-martensite occurs in stepwise bursts. These stepwise transformation events are correlated with stepwise increased lattice strains and peak broadening in the austenite phase. The stepwise transformation arises from growth of α-martensite embryos by autocatalytic transformation

  4. Solid-solid phase transitions in Fe nanowires induced by axial strain

    International Nuclear Information System (INIS)

    Sandoval, Luis; Urbassek, Herbert M

    2009-01-01

    By means of classical molecular-dynamics simulations we investigate the solid-solid phase transition from a bcc to a close-packed crystal structure in cylindrical iron nanowires, induced by axial strain. The interatomic potential employed has been shown to be capable of describing the martensite-austenite phase transition in iron. We study the stress versus strain curves for different temperatures and show that for a range of temperatures it is possible to induce a solid-solid phase transition by axial strain before the elasticity is lost; these transition temperatures are below the bulk transition temperature. The two phases have different (non-linear) elastic behavior: the bcc phase softens, while the close-packed phase stiffens with temperature. We also consider the reversibility of the transformation in the elastic regimes, and the role of the strain rate on the critical strain necessary for phase transition.

  5. Radiation-induced mutagenicity and lethality in Ames tester strains of Salmonella

    International Nuclear Information System (INIS)

    Isildar, M.; Bakale, G.

    1984-01-01

    Mutation and killing induced by X radiation and 60 Co γ radiation were studied in six different histidine-requiring auxotrophs of Salmonella typhimurium. Strain TA100, which is sensitive to base-pair substitutions, and strains TA2637 and TA98, which are sensitive to frameshifts, carry the pKM101 plasmid and exhibit significantly higher radiation-induced mutations compared to their plasmidless parent strains TA1535, TA1537, and TA1538, respectively. Among the plasmid-containing strains, TA98 and TA2637 are much more sensitive to the mutagenic action of radiation than is TA100 based on a comparison with their respective spontaneous mutation rates; however, no uniformity was observed in the responses of the strains to the lethal action of ionizing radiation. The following conclusions are consistent with these observations: (1) the standard Ames Salmonella assay correctly identifies ionizing radiation as a mutagenic agent; (2) frameshift-sensitive parent strains are more sensitive to the mutagenic effects of ionizing radiation than is the only strain studied that is sensitive to base-pair substitutions; and (3) enhancement of mutagenesis and survival is related to plasmid-mediated repair of DNA damage induced by ionizing radiation and does not involve damage induced by Cerenkov-generated uv radiation which is negligible for our irradiation conditions

  6. Antibodies with higher bactericidal activity induced by a Neisseria gonorrhoeae Rmp deletion mutant strain.

    Directory of Open Access Journals (Sweden)

    Guocai Li

    Full Text Available Neisseria gonorrhoeae (N. gonorrhoeae outer membrane protein reduction modifiable protein (Rmp has strong immunogenicity. However, anti-Rmp antibodies block rather than preserve the antibacterial effects of protective antibodies, which hampers the development of vaccines for gonococcal infections. We herein constructed an Rmp deletion mutant strain of N. gonorrhoeae by gene homologous recombination. The 261-460 nucleotide residues of Rmp gene amplified from N. gonorrhoeae WHO-A strain were replaced with a kanamycin-resistant Kan gene amplified from pET-28a. The resultant hybridized DNA was transformed into N. gonorrhoeae WHO-A strain. PCR was used to screen the colonies in which wild-type Rmp gene was replaced with a mutant gene fragment. Western blotting revealed that the Rmp deletion mutant strain did not express Rmp protein. Rmp deletion did not alter the morphological and Gram staining properties of the mutant strain that grew slightly more slowly than the wild-type one. Rmp gene mutated stably throughout 25 generations of passage. Antibody-mediated complement-dependent cytotoxicity assay indicated that the antibodies induced by the mutant strain had evidently higher bactericidal activities than those induced by the wild-type strain. Further modification of the Rmp deletion mutant strain is still required in the development of novel live attenuated vaccines for gonorrhea by Opa genes deletion or screening of phenotypic variant strains that do not express Opa proteins.

  7. Strain-typical patterns of pregnancy-induced nestbuilding in mice: maternal and experiential influences.

    Science.gov (United States)

    Broida, J; Svare, B

    1982-07-01

    Pregnant C57BL/6J mice incorporate less material into maternal nests and build fewer fully enclosed nests than do pregnant DBA/2J mice. These strain differences are not ameliorated by additional reproductive experience since multiparous animals also exhibit a similar pattern. Reciprocally-crossed hybrid females exhibit DBA-like levels of pregnancy-induced nestbuilding and cross-fostered C57BL and DBA females retain the phenotype of their strain. Experiential and maternal environmental factors apparently are not responsible for strain differences in pregnancy-induced nestbuilding. Differences in ovarian function and/or central neural tissue sensitivity to ovarian hormones may modulate strain differences in pregnancy-induced nestbuilding.

  8. Buckling induced by cyclic straining: Analysis of simple models

    International Nuclear Information System (INIS)

    Devos, J.; Gontier, C.; Hoffmann, A.

    1983-01-01

    Progressive buckling of a structure may occur under imposed loads below the critical value in cases where progressive distortion due to cyclic straining is possible. This interaction between ratchetting and buckling is usually not taken into account in design rules, such as the ASME rules. This paper presents the complete analysis of two simple cases and gives rules established on this basis. The first model is a modified version of SHANLEY's two bars; it is submitted to a constant axial compressive force F and a variable thermal stress Q. It simulates a compressed clamped-clamped beam subjected to a variable through-thickness thermal gradient. The second model is a refined version of the first taking into account strain-hardening of the deformable sections. One finds that progressive buckling is possible only if the applied force F is greater than SHANLEY's critical load and tangent moduli of the moment-curvature law, respectively. (orig./GL)

  9. Immobilization induced osteopenia is strain specific in mice

    DEFF Research Database (Denmark)

    Lodberg, Andreas; Vegger, Jens Bay; Jensen, Michael Vinkel

    2015-01-01

    systemic effects on bone. Female mice from four inbred mouse strains (BALB/cJ, C57BL/6 J, DBA/2 J, and C3H/HeN) were injected unilaterally with BTX (n = 10/group) or unilaterally with saline (n = 10/group). Mice were euthanized after 21 days, and the bone properties evaluated using μCT, DXA, bone...... resolution μCT we found no evidence of a systemic effect on any of the microstructural parameters of the contralateral limb. Likewise, there was no evidence of a systemic effect on the bone strength in any mouse strain. We did, however, find a small systemic effect on aBMD in DBA/2 J and C3H/HeN mice...

  10. Strain-induced gap transition and anisotropic Dirac-like cones in monolayer and bilayer phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Can; Xia, Qinglin, E-mail: qlxia@csu.edu.cn; Nie, Yaozhuang; Guo, Guanghua, E-mail: guogh@csu.edu.cn [School of Physics and Electronics, Central South University, Changsha 410083 (China)

    2015-03-28

    The electronic properties of two-dimensional monolayer and bilayer phosphorene subjected to uniaxial and biaxial strains have been investigated using first-principles calculations based on density functional theory. Strain engineering has obvious influence on the electronic properties of monolayer and bilayer phosphorene. By comparison, we find that biaxial strain is more effective in tuning the band gap than uniaxial strain. Interestingly, we observe the emergence of Dirac-like cones by the application of zigzag tensile strain in the monolayer and bilayer systems. For bilayer phosphorene, we induce the anisotropic Dirac-like dispersion by the application of appropriate armchair or biaxial compressive strain. Our results present very interesting possibilities for engineering the electronic properties of phosphorene and pave a way for tuning the band gap of future electronic and optoelectronic devices.

  11. Investigation of strain-induced magnetization change in ferromagnetic microparticles

    International Nuclear Information System (INIS)

    Chuklanov, A P; Nurgazizov, N I; Bizyaev, D A; Khanipov, T F; Bukharaev, A A; Yu Petukhov, V; Chirkov, V V; Gumarov, G G

    2016-01-01

    This work is devoted to investigation of magnetoelastic strain effect on the ferromagnetic microparticles of permalloy. An original method of sample fabrication with compressed microparticles is proposed. Magnetic force microscopy and magneto-optical Kerr experiments were carried out with unstrained and compressed microparticles. The domain walls transformation in compressed microparticles is in good agreement with numerical calculations. Hard axis of magnetization was observed on the compressed sample. (paper)

  12. Strain rate sensitivity and evolution of dislocations and twins in a twinning-induced plasticity steel

    International Nuclear Information System (INIS)

    Liang, Z.Y.; Wang, X.; Huang, W.; Huang, M.X.

    2015-01-01

    The present work investigated the effect of strain rates (10 −3 to 10 3 s −1 ) on the deformation behaviour of a twinning-induced plasticity (TWIP) steel. The strain rate sensitivity was studied in terms of instantaneous strain rate sensitivity (ISRS) and strain rate sensitivity of work-hardening (SRSW). While ISRS concerns the instantaneous flow stress change upon strain rate jump, SRSW deals with the subsequent modification in microstructure evolution, i.e. change of work-hardening rate. The present TWIP steel demonstrates a positive ISRS which remains stable during deformation and a negative SRSW, i.e. lower work-hardening rate at higher strain rate. Synchrotron X-ray diffraction experiments indicate that the negative SRSW should be attributed to the suppression of dislocations and deformation twins at high strain rate. This unexpected finding is different to conventional face-centred cubic (fcc) metals which generally show enhanced work-hardening rate at higher strain rate. A constitutive model which is strain rate- and temperature-dependent is developed to explain the stable ISRS and the negative SRSW. The modelling results reveal that the stable ISRS should be attributed to the thermally-activated dislocation motion dominated by interstitial carbon atoms and the negative SRSW should be due to the suppression of the dislocations and deformation twins caused by the adiabatic heating associated with high strain rate deformation

  13. Biaxial direct tensile tests in a large range of strain rates. Results on a ferritic nuclear steel

    Energy Technology Data Exchange (ETDEWEB)

    Albertini, C.; Labibes, K.; Montagnani, M.; Pizzinato, E.V.; Solomos, G.; Viaccoz, B. [Commission of the European Communities, Ispra (Italy). Joint Research Centre

    2000-09-01

    Constitutive equations are usually calibrated only trough the experimental results obtained by means of unixial tests because of the lack of adequate biaxial experimental data especially at high strain rate conditions. These data are however important for the validation of analytical models and also for the predictions of mechanical behaviour of real structures subjected to multiaxial loading by numerical simulations. In this paper some developments are shown concerning biaxial cruciform specimens and different experimental machines allowing biaxial tests in a large range of strain rates. This experimental campaign has also allowed study of the influence of changing the strain paths. Diagrams of equivalent stress versus straining direction and also equivalent plastic fracture strain versus straining direction are shown. (orig.)

  14. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    Science.gov (United States)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-01

    A spintronic device, called the "strain assisted spin transfer torque (STT) random access memory (RAM)," is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  15. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    International Nuclear Information System (INIS)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-01-01

    A spintronic device, called the “strain assisted spin transfer torque (STT) random access memory (RAM),” is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  16. Lattice strain induced multiferroicity in PZT-CFO particulate composite

    Science.gov (United States)

    Pradhan, Lagen Kumar; Pandey, Rabichandra; Kumar, Rajnish; Kar, Manoranjan

    2018-02-01

    Lead Zirconate Titanate [Pb(Zr0.52Ti0.48)O3/PZT] and Cobalt Ferrite [CoFe2O4/CFO] based multiferroic composites [(1-x)PZT-(x)CFO] with (x = 0.10-0.40) have been prepared to study its magnetoelectric (ME) and multiferroic properties. X-ray diffraction method along with the Rietveld refinement technique reveals that the crystal symmetries corresponding to PZT and CFO exist independently in the composites. The effect of interfacial strain on lattice distortion in PZT has been observed. It is well correlated with the magnetoelectric coupling of the composites. Dispersion behavior of dielectric constant with frequency can be explained by the modified Debye model. Different relaxation phenomena have been observed in PZT-CFO particulate composites. The ferroelectric properties of composites decrease with the increase in percentage of CFO in the composite. Both saturation (Ms) and remanent (Mr) magnetization increase with the increase in CFO content in the composite. The maximum ME coupling was found to be 1.339 pC/cm2 Oe for the composition (0.80) PZT-(0.20) CFO at the application of maximum magnetic field of 50 Oe. The multiferroic properties in CFO-PZT can be explained by the lattice strain at the CFO-PZT interfaces.

  17. On modeling the large strain fracture behaviour of soft viscous foods

    Science.gov (United States)

    Skamniotis, C. G.; Elliott, M.; Charalambides, M. N.

    2017-12-01

    Mastication is responsible for food breakdown with the aid of saliva in order to form a cohesive viscous mass, known as the bolus. This influences the rate at which the ingested food nutrients are later absorbed into the body, which needs to be controlled to aid in epidemic health problems such as obesity, diabetes, and dyspepsia. The aim of our work is to understand and improve food oral breakdown efficiency in both human and pet foods through developing multi-scale models of oral and gastric processing. The latter has been a challenging task and the available technology may be still immature, as foods usually exhibit a complex viscous, compliant, and tough mechanical behaviour. These are all addressed here through establishing a novel material model calibrated through experiments on starch-based food. It includes a new criterion for the onset of material stiffness degradation, a law for the evolution of degradation governed by the true material's fracture toughness, and a constitutive stress-strain response, all three being a function of the stress state, i.e., compression, shear, and tension. The material model is used in a finite element analysis which reproduces accurately the food separation patterns under a large strain indentation test, which resembles the boundary conditions applied in chewing. The results lend weight to the new methodology as a powerful tool in understanding how different food structures breakdown and in optimising these structures via parametric analyses to satisfy specific chewing and digestion attributes.

  18. Sensitivity of Spores of Eight Bacillus Cereus Strains to Pressure-Induced Germination by Moderate Hydrostatic Pressure, Time and Temperature

    National Research Council Canada - National Science Library

    Kalchayanand, Norasak; Ray, Bibek; Dunne, C. P; Sikes, Anthony

    2005-01-01

    The spores of eight Bacillus cereus strains were pressurized at 138 to 483 MPa for 5 to 20 min at 25 to 70 C in order to determine the sensitive and the resistant strains to pressure-induced germination...

  19. Dynamic strain aging of twinning-induced plasticity (TWIP) steel in tensile testing and deep drawing

    International Nuclear Information System (INIS)

    Kim, J.G.; Hong, S.; Anjabin, N.; Park, B.H.; Kim, S.K.; Chin, K.-G.; Lee, S.; Kim, H.S.

    2015-01-01

    The dynamic strain aging (DSA) of metallic materials due to solute atom diffusion to mobile dislocations induce deformation instability with load fluctuations and deformation localizations, hence reducing their sheet formability. In this paper, DSA behaviors of twinning induced plasticity (TWIP) steel with and without Al during tensile testing and deep drawing are investigated in terms of strain localization and the Portevin-Le Chatelier (PLC) band. A theoretical DSA model with internal variables of dislocation density and twin volume fraction is presented for an estimation of strain localization and strain hardening behavior of TWIP steels. The simulation results of the load history and PLC bands during tensile testing and deep drawing are in good agreement with the experimental values. A serration behavior is observed in high-Mn TWIP steels and its tensile residual stress is higher than that in the Al-added TWIP steels, which results in a deformation crack or delayed fracture of deep drawn specimens

  20. Coupled modeling and simulation of electro-elastic materials at large strains

    Science.gov (United States)

    Possart, Gunnar; Steinmann, Paul; Vu, Duc-Khoi

    2006-03-01

    In the recent years various novel materials have been developed that respond to the application of electrical loading by large strains. An example is the class of so-called electro-active polymers (EAP). Certainly these materials are technologically very interesting, e.g. for the design of actuators in mechatronics or in the area of artificial tissues. This work focuses on the phenomenological modeling of such materials within the setting of continuum-electro-dynamics specialized to the case of electro-hyperelastostatics and the corresponding computational setting. Thereby a highly nonlinear coupled problem for the deformation and the electric potential has to be considered. The finite element method is applied to solve the underlying equations numerically and some exemplary applications are presented.

  1. Strain induced irreversible critical current degradation in highly dense Bi-2212 round wire

    CERN Document Server

    Bjoerstad, R; Rikel, M.O.; Ballarino, A; Bottura, L; Jiang, J; Matras, M; Sugano, M; Hudspeth, J; Di Michiel, M

    2015-01-01

    The strain induced critical current degradation of overpressure processed straight Bi 2212/Ag wires has been studied at 77 K in self-field. For the first time superconducting properties, lattice distortions, composite wire stress and strain have been measured simultaneously in a high energy synchrotron beamline. A permanent Ic degradation of 5% occurs when the wire strain exceeds 0.60%. At a wire strain of about 0.65% a drastic n value and Ic reduction occur, and the composite stress and the Bi-2212 lattice parameter reach a plateau, indicating Bi-2212 filament fracturing. The XRD measurements show that Bi-2212 exhibits linear elastic behaviour up to the irreversible strain limit.

  2. Partial characterization of bacteriocin induced by irradiated and non-irradiated strain of yersinia enterocolitical

    International Nuclear Information System (INIS)

    Awny, N.M.

    1991-01-01

    Twenty isolates of yersinia enterocolitica were tested for the inhibition of the growth of different strains of yersinia. The screening tests revealed three possible bacteriocinogenic strains. One of them was selected for additional studies after it was shown that its inhibitory substances differed in their activity spectra. The gamma irradiated strain lost the ability to produce bacteriocin at 0.6 kGy level. Crude preparation of bacteriocin obtained from the wild strain were not affected by chloroform or other organic solvents but inactivated by trypsin and heating at 80 C for 45 min. Bacteriocin induced by irradiated strain was easily inactivated by thermal treatment. Exposure of agar fragments containing the inhibitory active component to a pH value ranging between 2 to 11 did not affect bactericidal activity.4 tab

  3. Ultraviolet-induced reversion of cyc1 alleles in radiation-sensitive strains of yeast. III. rev 3 mutant strains

    International Nuclear Information System (INIS)

    Lawrence, C.W.; Crhistensen, R.B.

    1979-01-01

    The role of rev3 gene function in uv-induced mutagenesis in the yeast Saccharomyces cerevisiae has been examined by determining the reversion of 12 well-defined cyc1 mutations in diploid strains homozygous for the rev3-1 or rev3-3 allale. The 12 cyc1 alleles include one ochre, one amber, four initiation, two proline missense, and four frameshift mutations. We find that the rev3 mutations reduce the frequency of UV-induced reversion of all of the cyc1 alleles, though different classes of alleles respond to a different extent. These results imply that the rev3 gene function is required for the production of a wide variety of mutational events, though probably not all, and show that each of the three rev loci have different mutational phenotypes. Such diverse phenotypes are not predicted by the unitary model for bacterial mutagenes, suggesting that this is at best an incomplete description of eukaryotic mutagenesis

  4. Strain-induced fermi contour anisotropy of GaAs 2D holes.

    Science.gov (United States)

    Shabani, J; Shayegan, M; Winkler, R

    2008-03-07

    We report measurements of magnetoresistance commensurability peaks, induced by a square array of antidots, in GaAs (311)A two-dimensional holes as a function of applied in-plane strain. The data directly probe the shapes of the Fermi contours of the two spin subbands that are split thanks to the spin-orbit interaction and strain. The experimental results are in quantitative agreement with the predictions of accurate energy band calculations, and reveal that the majority spin subband has a severely distorted Fermi contour whose anisotropy can be tuned with strain.

  5. Modeling Shock Induced Plasticity in Copper Single Crystal: Numerical and Strain Localization Issues

    International Nuclear Information System (INIS)

    Shehadeh, M

    2011-01-01

    Multiscale dislocation dynamics plasticity (MDDP) simulations are carried out to address the following issues in modeling shock-induced plasticity: 1- the effect of finite element (FE) boundary conditions on shock wave characteristics and wave-dislocation interaction, 2- the effect of the evolution of the dislocation microstructure on lattice rotation and strain localization. While uniaxial strain is achieved with high accuracy using confined boundary condition, periodic boundary condition yields a disturbed wave profile due the edge effect. Including lattice rotation in the analysis leads to higher dislocation density and more localized plastic strain. (author)

  6. Exercise-induced bone formation is poorly linked to local strain magnitude in the sheep tibia.

    Directory of Open Access Journals (Sweden)

    Ian J Wallace

    Full Text Available Functional interpretations of limb bone structure frequently assume that diaphyses adjust their shape by adding bone primarily across the plane in which they are habitually loaded in order to minimize loading-induced strains. Here, to test this hypothesis, we characterize the in vivo strain environment of the sheep tibial midshaft during treadmill exercise and examine whether this activity promotes bone formation disproportionately in the direction of loading in diaphyseal regions that experience the highest strains. It is shown that during treadmill exercise, sheep tibiae were bent in an anteroposterior direction, generating maximal tensile and compressive strains on the anterior and posterior shaft surfaces, respectively. Exercise led to significantly increased periosteal bone formation; however, rather than being biased toward areas of maximal strains across the anteroposterior axis, exercise-related osteogenesis occurred primarily around the medial half of the shaft circumference, in both high and low strain regions. Overall, the results of this study demonstrate that loading-induced bone growth is not closely linked to local strain magnitude in every instance. Therefore, caution is necessary when bone shaft shape is used to infer functional loading history in the absence of in vivo data on how bones are loaded and how they actually respond to loading.

  7. Strain-induced bi-thermoelectricity in tapered carbon nanotubes

    Science.gov (United States)

    Algharagholy, L. A. A.; Pope, T.; Lambert, C. J.

    2018-03-01

    We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient. These results reveal that tapered CNTs form a new class of bi-thermoelectric materials, exhibiting both positive and negative thermopower. This ability to change the sign of the Seebeck coefficient allows the thermovoltage in carbon-based thermoelectric devices to be boosted by placing CNTs with alternating-sign Seebeck coefficients in tandem.

  8. Screening and characterization of Lactobacillus strains producing large amounts of exopolysaccharides

    NARCIS (Netherlands)

    Geel-Schutten, G.H. van; Flesch, F.; Brink, B. ten; Smith, M.R.; Dijkhuizen, L.

    1998-01-01

    A total of 182 Lactobacillus strains were screened for production of extracellular polysaccharides (EPS) by a new method: growth in liquid media with high sugar concentrations. Sixty EPS-positive strains were identified; 17 strains produced more than 100 mg/l soluble EPS. Sucrose was an excellent

  9. Investigation of strain-induced martensitic transformation in metastable austenite using nanoindentation

    International Nuclear Information System (INIS)

    Ahn, T.-H.; Oh, C.-S.; Kim, D.H.; Oh, K.H.; Bei, H.; George, E.P.; Han, H.N.

    2010-01-01

    Strain-induced martensitic transformation of metastable austenite was investigated by nanoindentation of individual austenite grains in multi-phase steel. A cross-section prepared through one of these indented regions using focused ion beam milling was examined by transmission electron microscopy. The presence of martensite underneath the indent indicates that the pop-ins observed on the load-displacement curve during nanoindentation correspond to the onset of strain-induced martensitic transformation. The pop-ins can be understood as resulting from the selection of a favorable martensite variant during nanoindentation.

  10. Investigation of Strain-Induced Martensitic Transformation in Metastable Austenite using Nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, T.-H. [Seoul National University; Oh, C.-S. [Korean Institute of Materials Science; Kim, D. H. [Seoul National University; Oh, K. H. [Seoul National University; Bei, Hongbin [ORNL; George, Easo P [ORNL; Han, H. N. [Seoul National University

    2010-01-01

    Strain-induced martensitic transformation of metastable austenite was investigated by nanoindentation of individual austenite grains in multi-phase steel. A cross-section prepared through one of these indented regions using focused ion beam milling was examined by transmission electron microscopy. The presence of martensite underneath the indent indicates that the pop-ins observed on the load-displacement curve during nanoindentation correspond to the onset of strain-induced martensitic transformation. The pop-ins can be understood as resulting from the selection of a favorable martensite variant during nanoindentation.

  11. Strain- and electric field-induced band gap modulation in nitride nanomembranes

    International Nuclear Information System (INIS)

    Amorim, Rodrigo G; Zhong Xiaoliang; Mukhopadhyay, Saikat; Pandey, Ravindra; Rocha, Alexandre R; Karna, Shashi P

    2013-01-01

    The hexagonal nanomembranes of the group III-nitrides are a subject of interest due to their novel technological applications. In this paper, we investigate the strain- and electric field-induced modulation of their band gaps in the framework of density functional theory. For AlN, the field-dependent modulation of the bandgap is found to be significant whereas the strain-induced semiconductor-metal transition is predicted for GaN. A relatively flat conduction band in AlN and GaN nanomembranes leads to an enhancement of their electronic mobility compared to that of their bulk counterparts. (paper)

  12. Quantification of gravity-induced skin strain across the breast surface.

    Science.gov (United States)

    Sanchez, Amy; Mills, Chris; Haake, Steve; Norris, Michelle; Scurr, Joanna

    2017-12-01

    Quantification of the magnitude of skin strain in different regions of the breast may help to estimate possible gravity-induced damage whilst also being able to inform the selection of incision locations during breast surgery. The aim of this study was to quantify static skin strain over the breast surface and to estimate the risk of skin damage caused by gravitational loading. Fourteen participants had 21 markers applied to their torso and left breast. The non-gravity breast position was estimated as the mid-point of the breast positions in water and soybean oil (higher and lower density than breast respectively). The static gravity-loaded breast position was also measured. Skin strain was calculated as the percentage extension between adjacent breast markers in the gravity and non-gravity loaded conditions. Gravity induced breast deformation caused peak strains ranging from 14 to 75% across participants, with potentially damaging skin strain (>60%) in one participant and skin strains above 30% (skin resistance zone) in a further four participants. These peak strain values all occurred in the longitudinal direction in the upper region of the breast skin. In the latitudinal direction, smaller-breasted participants experienced greater strain on the outer (lateral) breast regions and less strain on the inner (medial) breast regions, a trend which was reversed in the larger breasted participants (above size 34D). To reduce tension on surgical incisions it is suggested that preference should be given to medial latitudinal locations for smaller breasted women and lateral latitudinal locations for larger breasted women. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Studies on the graphite rupture under irradiation induced strains

    International Nuclear Information System (INIS)

    Jouquet, G.; Berthion, Y.; L'Homme, A.

    1980-01-01

    Following the RMG experiments (failure of graphite by mechanical effect, i.e. under very high temperature gradient) an experimental program called RWG (Failure of Graphite by WIGNER effect) was initiated in 75 at C.E.A. 3 experiments have been already performed in the OSIRIS reactor at Saclay: RWG 01, 02 and 03. A 4th one, RWG04, is scheduled for the end of 79, may be in collaboration with GERMANY. The aim of the RWG experiments is to induce internal stresses in graphite blocks by irradiation at high temperature which would lead or not to their failure so one could bracket, as tightly as possible, the critical value for failure onset in given experimental conditions

  14. Large-strain time-temperature equivalence in high density polyethylene for prediction of extreme deformation and damage

    Directory of Open Access Journals (Sweden)

    Gray G.T.

    2012-08-01

    Full Text Available Time-temperature equivalence is a widely recognized property of many time-dependent material systems, where there is a clear predictive link relating the deformation response at a nominal temperature and a high strain-rate to an equivalent response at a depressed temperature and nominal strain-rate. It has been found that high-density polyethylene (HDPE obeys a linear empirical formulation relating test temperature and strain-rate. This observation was extended to continuous stress-strain curves, such that material response measured in a load frame at large strains and low strain-rates (at depressed temperatures could be translated into a temperature-dependent response at high strain-rates and validated against Taylor impact results. Time-temperature equivalence was used in conjuction with jump-rate compression tests to investigate isothermal response at high strain-rate while exluding adiabatic heating. The validated constitutive response was then applied to the analysis of Dynamic-Tensile-Extrusion of HDPE, a tensile analog to Taylor impact developed at LANL. The Dyn-Ten-Ext test results and FEA found that HDPE deformed smoothly after exiting the die, and after substantial drawing appeared to undergo a pressure-dependent shear damage mechanism at intermediate velocities, while it fragmented at high velocities. Dynamic-Tensile-Extrusion, properly coupled with a validated constitutive model, can successfully probe extreme tensile deformation and damage of polymers.

  15. Anisotropic chemical strain in cubic ceria due to oxygen-vacancy-induced elastic dipoles.

    Science.gov (United States)

    Das, Tridip; Nicholas, Jason D; Sheldon, Brian W; Qi, Yue

    2018-06-06

    Accurate characterization of chemical strain is required to study a broad range of chemical-mechanical coupling phenomena. One of the most studied mechano-chemically active oxides, nonstoichiometric ceria (CeO2-δ), has only been described by a scalar chemical strain assuming isotropic deformation. However, combined density functional theory (DFT) calculations and elastic dipole tensor theory reveal that both the short-range bond distortions surrounding an oxygen-vacancy and the long-range chemical strain are anisotropic in cubic CeO2-δ. The origin of this anisotropy is the charge disproportionation between the four cerium atoms around each oxygen-vacancy (two become Ce3+ and two become Ce4+) when a neutral oxygen-vacancy is formed. Around the oxygen-vacancy, six of the Ce3+-O bonds elongate, one of the Ce3+-O bond shorten, and all seven of the Ce4+-O bonds shorten. Further, the average and maximum chemical strain values obtained through tensor analysis successfully bound the various experimental data. Lastly, the anisotropic, oxygen-vacancy-elastic-dipole induced chemical strain is polarizable, which provides a physical model for the giant electrostriction recently discovered in doped and non-doped CeO2-δ. Together, this work highlights the need to consider anisotropic tensors when calculating the chemical strain induced by dilute point defects in all materials, regardless of their symmetry.

  16. Cyclic strain-induced endothelial MMP-2: role in vascular smooth muscle cell migration

    International Nuclear Information System (INIS)

    Sweeney, Nicholas von Offenberg; Cummins, Philip M.; Birney, Yvonne A.; Redmond, Eileen M.; Cahill, Paul A.

    2004-01-01

    Matrix metalloproteinases (MMPs) play a vital role in vasculature response to hemodynamic stimuli via the degradation of extracellular matrix substrates. In this study, we investigated the putative role of cyclic strain-induced endothelial MMP-2 (and MMP-9) expression and release in modulating bovine aortic smooth muscle cell (BASMC) migration in vitro. Equibiaxial cyclic strain of bovine aortic endothelial cells (BAECs) leads to elevation in cellular MMP-2 (and MMP-9) expression, activity, and secretion into conditioned media, events which were time- and force-dependent. Subsequent incubation of BASMCs with conditioned media from chronically strained BAECs (5%, 24 h) significantly reduces BASMC migration (38 ± 6%), an inhibitory effect which could be completely reversed by targeted siRNA 'knock-down' of MMP-2 (but not MMP-9) expression and activity in BAECs. Moreover, inhibition of strain-mediated MMP-2 expression in BAECs by protein tyrosine kinase (PTK) blockade with genistein (50 μM) was also found to completely reverse this inhibitory effect on BASMC migration. Finally, direct supplementation of recombinant MMP-2 into the BASMC migration assay was found to have no significant effect on migration. However, the effect on BASMC migration of MMP-2 siRNA transfection in BAECs could be reversed by supplementation of recombinant MMP-2 into BAEC media prior to (and for the duration of) strain. These findings reveal a potentially novel role for strain-induced endothelial MMP-2 in regulating vascular SMC migration

  17. Effect of strain-induced precipitation on dynamic recrystallization in Mg–Al–Sn alloys

    International Nuclear Information System (INIS)

    Kabir, Abu Syed Humaun; Sanjari, Mehdi; Su, Jing; Jung, In-Ho; Yue, Stephen

    2014-01-01

    Two different amounts of tin (Sn) were added to a Mg–3 wt% Al binary alloy to form different amounts of precipitates during hot deformation. The thermodynamic modeling software, FactSage ™ , was used to calculate the amounts of Sn to generate the desired relative levels of precipitation. The alloys were deformed at four different temperatures and three different strain rates to generate different amounts of precipitates. The objective was to study the effect of these precipitates on dynamic recrystallization. The results indicated that the formation of strain-induced precipitates is a function of deformation temperature, strain, and strain rate. The findings also revealed that higher amounts of precipitates reduced the volume fraction of dynamic recrystallization and refined the dynamically recrystallized grain size

  18. Anisotropic Constitutive Model of Strain-induced Phenomena in Stainless Steels at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2004-01-01

    A majority of the thin-walled components subjected to intensive plastic straining at cryogenic temperatures are made of stainless steels. The examples of such components can be found in the interconnections of particle accelerators, containing the superconducting magnets, where the thermal contraction is absorbed by thin-walled, axisymetric shells called bellows expansion joints. The stainless steels show three main phenomena induced by plastic strains at cryogenic temperatures: serrated (discontinuous) yielding, gamma->alpha' phase transformation and anisotropic ductile damage. In the present paper, a coupled constitutive model of gamma->alpha' phase transformation and orthotropic ductile damage is presented. A kinetic law of phase transformation, and a kinetic law of evolution of orthotropic damage are presented. The model is extended to anisotropic plasticity comprising a constant anisotropy (texture effect), which can be classically taken into account by the Hill yield surface, and plastic strain induced ...

  19. Novel spin-electronic properties of BC{sub 7} sheets induced by strain

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Dai, ZhenHong, E-mail: zhdai@ytu.edu.cn; Sui, PengFei; Sun, YuMing; Wang, WeiTian [Computational Physics Laboratory, Institute of Opto-Electronic Information Science and Technology, Yantai University, Yantai 264005 (China)

    2014-11-01

    Based on first-principles calculations, the authors have investigated the electronic and magnetic properties of BC{sub 7} sheets with different planar strains. It is found that metal–semiconductor transition appears at the biaxial strain of 15.5%, and the sheets are characteristic of spin-polarized semiconductor with a zero band-gap. The band-gap rapidly increases with strain, and reaches a maximum value of 0.60 eV at the strain of 20%. Subsequently, the band-gap decreases until the strain reaches up to 22% and shows a semiconductor-half metal transformation. It will further present metal properties until the strain is up to the maximum value of 35%. The magnetic moments also have some changes induced by biaxial strain. The numerical analysis shows that the two-dimensional distortions have great influences on the magnetic moments. The novel spin-electronic properties make BC{sub 7} sheets have potential applications in future spintronic nanodevices.

  20. Novel spin-electronic properties of BC7 sheets induced by strain

    International Nuclear Information System (INIS)

    Xu, Lei; Dai, ZhenHong; Sui, PengFei; Sun, YuMing; Wang, WeiTian

    2014-01-01

    Based on first-principles calculations, the authors have investigated the electronic and magnetic properties of BC 7 sheets with different planar strains. It is found that metal–semiconductor transition appears at the biaxial strain of 15.5%, and the sheets are characteristic of spin-polarized semiconductor with a zero band-gap. The band-gap rapidly increases with strain, and reaches a maximum value of 0.60 eV at the strain of 20%. Subsequently, the band-gap decreases until the strain reaches up to 22% and shows a semiconductor-half metal transformation. It will further present metal properties until the strain is up to the maximum value of 35%. The magnetic moments also have some changes induced by biaxial strain. The numerical analysis shows that the two-dimensional distortions have great influences on the magnetic moments. The novel spin-electronic properties make BC 7 sheets have potential applications in future spintronic nanodevices

  1. Parameters of straining-induced corrosion cracking in low-alloy steels in high temperature water

    International Nuclear Information System (INIS)

    Lenz, E.; Liebert, A.; Stellwag, B.; Wieling, N.

    Tensile tests with slow deformation speed determine parameters of corrosion cracking at low strain rates of low-alloy steels in high-temperature water. Besides the strain rate the temperature and oxygen content of the water prove to be important for the deformation behaviour of the investigated steels 17MnMoV64, 20 MnMoNi55 and 15NiCuMoNb 5. Temperatures about 240 0 C, increased oxygen contents in the water and low strain rates cause a decrease of the material ductility as against the behaviour in air. Tests on the number of stress cycles until incipient cracking show that the parameters important for corrosion cracking at low strain velocities apply also to low-frequency cyclic loads with high strain amplitude. In knowledge of these influencing parameters the strain-induced corrosion cracking is counteracted by concerted measures taken in design, construction and operation of nuclear power stations. Essential aims in this matter are to avoid as far as possible inelastic strains and to fix and control suitable media conditions. (orig.) [de

  2. Eraser-based eco-friendly fabrication of a skin-like large-area matrix of flexible carbon nanotube strain and pressure sensors.

    Science.gov (United States)

    Sahatiya, Parikshit; Badhulika, Sushmee

    2017-03-03

    This paper reports a new type of electronic, recoverable skin-like pressure and strain sensor, produced on a flexible, biodegradable pencil-eraser substrate and fabricated using a solvent-free, low-cost and energy efficient process. Multi-walled carbon nanotube (MWCNT) film, the strain sensing element, was patterned on pencil eraser with a rolling pin and a pre-compaction mechanical press. This induces high interfacial bonding between the MWCNTs and the eraser substrate, which enables the sensor to achieve recoverability under ambient conditions. The eraser serves as a substrate for strain sensing, as well as acting as a dielectric for capacitive pressure sensing, thereby eliminating the dielectric deposition step, which is crucial in capacitive-based pressure sensors. The strain sensing transduction mechanism is attributed to the tunneling effect, caused by the elastic behavior of the MWCNTs and the strong mechanical interlock between MWCNTs and the eraser substrate, which restricts slippage of MWCNTs on the eraser thereby minimizing hysteresis. The gauge factor of the strain sensor was calculated to be 2.4, which is comparable to and even better than most of the strain and pressure sensors fabricated with more complex designs and architectures. The sensitivity of the capacitive pressure sensor was found to be 0.135 MPa -1 .To demonstrate the applicability of the sensor as artificial electronic skin, the sensor was assembled on various parts of the human body and corresponding movements and touch sensation were monitored. The entire fabrication process is scalable and can be integrated into large areas to map spatial pressure distributions. This low-cost, easily scalable MWCNT pin-rolled eraser-based pressure and strain sensor has huge potential in applications such as artificial e-skin in flexible electronics and medical diagnostics, in particular in surgery as it provides high spatial resolution without a complex nanostructure architecture.

  3. Quantifying the strain-induced dissolution of precipitates in Al alloy microstructures using nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Hutchinson, C.R.; Loo, P.T.; Bastow, T.J.; Hill, A.J.; Costa Teixeira, J. da

    2009-01-01

    Nuclear magnetic resonance (NMR) has been used for the first time to directly monitor the dynamic partitioning of Cu atoms from shearable precipitates into the solid solution as a function of straining at room temperature in two Al-Cu-based alloys. Al-3Cu-0.05Sn (wt.%) and Al-2.5Mg-1.5Cu (wt.%) alloys were heat-treated to provide a fine distribution of ∼5 nm Guinier-Preston (GP) zones and <1 nm Guinier-Preston-Bagaryatsky (GPB) zones, respectively, and were then subjected to rolling strains up to 100%. It is shown that in the Al-Cu-0.05Sn alloy, strains up to ∼40% can pump solute from the ∼5 nm GP zones back into solid solution for the temperature and strain-rate of deformation employed here. In the case of the Al-Cu-Mg alloy, no dissolution of the GPB zones is observed. A simple model for the strain-induced dissolution of the shearable precipitates is given and compared with the experimental results. The dependence of the Cu repartitioning process on the precipitate size is emphasized. These observations and modeling give guidelines for the design of Al-Cu-based alloys to exploit the dynamic interplay of strain-induced Cu partitioning between metastable states, e.g. solid solution and GP (or GPB) zones, for tailoring ultimate mechanical properties. It is proposed that this strain-induced phase transformation is a form of dynamically responding microstructure that can be employed to obtain aluminum alloys with well-designed microstructures.

  4. The demand-induced strain compensation model : renewed theoretical considerations and empirical evidence

    NARCIS (Netherlands)

    de Jonge, J.; Dormann, C.; van den Tooren, M.; Näswall, K.; Hellgren, J.; Sverke, M.

    2008-01-01

    This chapter presents a recently developed theoretical model on jobrelated stress and performance, the so-called Demand-Induced Strain Compensation (DISC) model. The DISC model predicts in general that adverse health effects of high job demands can best be compensated for by matching job resources

  5. Comparative Study of Histopathologic Characterization of Azoxymethane-induced Colon Tumors in Three Inbred Rat Strains

    DEFF Research Database (Denmark)

    Kobæk Larsen, Morten; Fenger, Claus; Hansen, Ket

    2002-01-01

    To obtain controlled genetic variation, colon cancer was chemically induced by use of four subcutaneous injections of azoxymethane (15 mg/kg of body weight/wk) to rats of 3 inbred strains (BDIX/OrlIco, F344/NHsd, WAG/Rij). The selection was based on the availability of established colon cancer cell...

  6. Quantum transport in graphene in presence of strain-induced pseudo-Landau levels

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Leconte, Nicolas; Barrios-Vargas, Jose E.

    2016-01-01

    We report on mesoscopic transport fingerprints in disordered graphene caused by strain-field induced pseudomagnetic Landau levels (pLLs). Efficient numerical real space calculations of the Kubo formula are performed for an ordered network of nanobubbles in graphene, creating pseudomagnetic fields...

  7. Coculture-inducible bacteriocin biosynthesis of different probiotic strains by dairy starter culture Lactococcus lactis

    Directory of Open Access Journals (Sweden)

    Blaženka Kos

    2011-12-01

    Full Text Available Bacteriocins produced by probiotic strains effectively contribute to colonization ability of probiotic strains and facilitate their establishment in the competitive gut environment and also protect the gut from gastrointestinal pathogens. Moreover, bacteriocins have received considerable attention due to their potential application as biopreservatives, especially in dairy industry. Hence, the objective of this research was to investigate antimicrobial activity of probiotic strains Lactobacillus helveticus M92, Lactobacillus plantarum L4 and Enterococcus faecium L3, with special focus on their bacteriocinogenic activity directed towards representatives of the same or related bacterial species, and towards distant microorganisms including potential food contaminants or causative agents of gut infections. In order to induce bacteriocin production, probiotic cells were cocultivated with Lactococcus lactis subsp. lactis LMG 9450, one of the most important starter cultures in cheese production. The presence of bacteriocin coding genes was investigated by PCR amplification with sequence-specific primers for helveticin and was confirmed for probiotic strain L. helveticus M92. All examined probiotic strains have shown bacteriocinogenic activity against Staphylococcus aureus 3048, Staphylococcus aureus K-144, Escherichia coli 3014, Salmonella enterica serovar Typhimurium FP1, Bacillus subtilis ATCC 6633, Bacillus cereus TM2, which is an important functional treat of probiotic strains significant in competitive exclusion mechanism which provides selective advantage of probiotic strains against undesirable microorganisms in gastrointestinal tract of the host. According to obtained results, living cells of starter culture Lc. lactis subsp. lactis LMG 9450 induced bacteriocin production by examined probiotic strains but starter culture itself was not sensitive to bacteriocin activity.

  8. Fiber Optic Rosette Strain Gauge Development and Application on a Large-Scale Composite Structure

    Science.gov (United States)

    Moore, Jason P.; Przekop, Adam; Juarez, Peter D.; Roth, Mark C.

    2015-01-01

    A detailed description of the construction, application, and measurement of 196 FO rosette strain gauges that measured multi-axis strain across the outside upper surface of the forward bulkhead component of a multibay composite fuselage test article is presented. A background of the FO strain gauge and the FO measurement system as utilized in this application is given and results for the higher load cases of the testing sequence are shown.

  9. Thermal Stability of Ultrafine Grained Pure Copper Prepared by Large Strain Extrusion Machining

    Directory of Open Access Journals (Sweden)

    Bangxian Wu

    2018-05-01

    Full Text Available Ultrafine grained (UFG pure copper chips with improved material strength have been successfully prepared by large strain extrusion machining (LSEM. However, the thermal stability of the UFG chips has been a key characteristic that has restricted their use in practical applications. To understand the influence of annealing temperature and annealing time on their microstructures and mechanical properties, the UFG chips were subjected to isochronous and isothermal annealing treatments as well as Vickers hardness tests in the present study. From the results, we found that the UFG chips maintain high hardness when annealing at temperatures up to 160 °C but begin to exhibit a reduction in their hardness while the annealing temperature reached above 200 °C. When annealed at 280 °C for 10–240 min, the grain size increased slightly and reached a stable value of 2 µm with an increase in annealing time and with a decrease in the hardness of the chips. These results indicated that UFG pure copper chips have good thermal stability at temperatures below 160 °C.

  10. Commercial biocides induce transfer of prophage Φ13 from human strains of Staphylococcus aureus to livestock CC398

    DEFF Research Database (Denmark)

    Tang, Yuanyue; Nielsen, Lene Nørby; Hvitved, Annemette

    2017-01-01

    if exposure to biocidal products induces phage transfer, and find that during co-culture, Φ13 from strain 8325, belonging to ΦSa3 group, is induced and transferred from a human strain to LA-MRSA CC398 when exposed to sub-lethal concentrations of commercial biocides containing hydrogen peroxide. Integration...... variation in CC398 strains that disrupts the phage attachment site, but not the expression of β-hemolysin. Our results show that hydrogen peroxide present in biocidal products stimulate transfer of ΦSa3 from human to LA-MRSA CC398 strains and that in these strains prophage stability depends...

  11. Strain-dependent Damage Evolution and Velocity Reduction in Fault Zones Induced by Earthquake Rupture

    Science.gov (United States)

    Zhong, J.; Duan, B.

    2009-12-01

    Low-velocity fault zones (LVFZs) with reduced seismic velocities relative to the surrounding wall rocks are widely observed around active faults. The presence of such a zone will affect rupture propagation, near-field ground motion, and off-fault damage in subsequent earth-quakes. In this study, we quantify the reduction of seismic velocities caused by dynamic rup-ture on a 2D planar fault surrounded by a low-velocity fault zone. First, we implement the damage rheology (Lyakhovsky et al. 1997) in EQdyna (Duan and Oglesby 2006), an explicit dynamic finite element code. We further extend this damage rheology model to include the dependence of strains on crack density. Then, we quantify off-fault continuum damage distribution and velocity reduction induced by earthquake rupture with the presence of a preexisting LVFZ. We find that the presence of a LVFZ affects the tempo-spatial distribu-tions of off-fault damage. Because lack of constraint in some damage parameters, we further investigate the relationship between velocity reduction and these damage prameters by a large suite of numerical simulations. Slip velocity, slip, and near-field ground motions computed from damage rheology are also compared with those from off-fault elastic or elastoplastic responses. We find that the reduction in elastic moduli during dynamic rupture has profound impact on these quantities.

  12. Stacked bilayer phosphorene: strain-induced quantum spin Hall state and optical measurement

    Science.gov (United States)

    Zhang, Tian; Lin, Jia-He; Yu, Yan-Mei; Chen, Xiang-Rong; Liu, Wu-Ming

    2015-01-01

    Bilayer phosphorene attracted considerable interest, giving a potential application in nanoelectronics owing to its natural bandgap and high carrier mobility. However, very little is known regarding the possible usefulness in spintronics as a quantum spin Hall (QSH) state of material characterized by a bulk energy gap and gapless spin-filtered edge states. Here, we report a strain-induced topological phase transition from normal to QSH state in bilayer phosphorene, accompanied by band-inversion that changes number from 0 to 1, which is highly dependent on interlayer stacking. When the bottom layer is shifted by 1/2 unit-cell along zigzag/armchair direction with respect to the top layer, the maximum topological bandgap 92.5 meV is sufficiently large to realize QSH effect even at room-temperature. An optical measurement of QSH effect is therefore suggested in view of the wide optical absorption spectrum extending to far infra-red, making bilayer phosphorene a promising candidate for opto-spintronic devices. PMID:26370771

  13. Genetic mapping of xenotropic murine leukemia virus-inducing loci in five mouse strains.

    Science.gov (United States)

    Kozak, C A; Rowe, W P

    1980-07-01

    A single mendelian gene was identified for induction of the endogenous xenotropic murine leukemia virus in five mouse strains (C57BL/10, C57L, C57BR, AKR, and BALB/c). This locus, designated Bxv-1, mapped to the same site on chromosome 1 in all strains: Id-1-Pep-3-[Bxv-1-Lp]. Thus, inducibility loci for xenotropic virus are more limited in number and chromosomal distribution than ecotropic inducibility loci. Virus expression in mice with Bxv-1 was induced by treatment of fibroblasts with 5-iododeoxyuridine or by exposure of spleen cells to a B cell mitogen, bacterial lipopolysaccharide. An analysis of the hamster X mouse somatic cell hybrids indicated that chromosome 1, alone, was sufficient for virus induction.

  14. Strain-induced collagen organization at the micro-level in fibrin-based engineered tissue constructs

    NARCIS (Netherlands)

    Jonge, de N.; Kanters, F.M.W.; Baaijens, F.P.T.; Bouten, C.V.C.

    2013-01-01

    Full understanding of strain-induced collagen organization in complex tissue geometries to create tissues with predefined collagen architecture has not been achieved. This is mainly due to our limited knowledge of collagen remodeling in developing tissues. Here we investigate strain-induced collagen

  15. An affine microsphere approach to modeling strain-induced crystallization in rubbery polymers

    Science.gov (United States)

    Nateghi, A.; Dal, H.; Keip, M.-A.; Miehe, C.

    2018-01-01

    Upon stretching a natural rubber sample, polymer chains orient themselves in the direction of the applied load and form crystalline regions. When the sample is retracted, the original amorphous state of the network is restored. Due to crystallization, properties of rubber change considerably. The reinforcing effect of the crystallites stiffens the rubber and increases the crack growth resistance. It is of great importance to understand the mechanism leading to strain-induced crystallization. However, limited theoretical work has been done on the investigation of the associated kinetics. A key characteristic observed in the stress-strain diagram of crystallizing rubber is the hysteresis, which is entirely attributed to strain-induced crystallization. In this work, we propose a micromechanically motivated material model for strain-induced crystallization in rubbers. Our point of departure is constructing a micromechanical model for a single crystallizing polymer chain. Subsequently, a thermodynamically consistent evolution law describing the kinetics of crystallization on the chain level is proposed. This chain model is then incorporated into the affine microsphere model. Finally, the model is numerically implemented and its performance is compared to experimental data.

  16. Inducing and manipulating magnetization in 2D zinc–oxide by strain and external voltage

    Science.gov (United States)

    Taivansaikhan, P.; Tsevelmaa, T.; Rhim, S. H.; Hong, S. C.; Odkhuu, D.

    2018-04-01

    Two-dimensional (2D) structures that exhibit intriguing magnetic phenomena such as perpendicular magnetic anisotropy and its switchable feature are of great interests in spintronics research. Herein, the density functional theory studies reveal the critical impacts of strain and external gating on vacancy-induced magnetism and its spin direction in a graphene-like single layer of zinc oxide (ZnO). In contrast to the pristine and defective ZnO with an O-vacancy, the presence of a Zn-vacancy induces significant magnetic moments to its first neighboring O and Zn atoms due to the charge deficit. We further predict that the direction of magnetization easy axis reverses from an in-plane to perpendicular orientation under a practically achievable biaxial compressive strain of only ~1–2% or applying an electric field by means of the charge density modulation. This magnetization reversal is mainly driven by the strain- and electric-field-induced changes in the spin–orbit coupled d states of the first-neighbor Zn atom to a Zn-vacancy. These findings open interesting prospects for exploiting strain and electric field engineering to manipulate magnetism and magnetization orientation of 2D materials.

  17. Culture supernatants from V. cholerae O1 El Tor strains isolated from different geographic areas induce cell vacuolation and cytotoxicity.

    Science.gov (United States)

    Vidal, Jorge E; Enríquez-Rincón, Fernando; Giono-Cerezo, Silvia; Ribas-Aparicio, Rosa María; Figueroa-Arredondo, Paula

    2009-01-01

    To investigate whether the HlyA-induced vacuolating effect is produced by V. cholerae O1 ElTor strains isolated from different geographic origins, including Mexico. Supernatant-induced haemolysis, vacuolating activity and cytotoxicity in Vero cells were recorded. PCR, RFLP analysis and molecular cloning were performed. All ElTor strains analyzed induced cellular vacuolation. Ribotype 2 strains isolates from the U.S. gulf coast yielded the highest titer of vacuolating activity. Eight of nine strains were haemolytic, while all strains were PCR positive for the hlyA gene. We cloned the hlyA gene from two ElTor strains, a toxigenic (2514-88, ctxAB+) and a non-toxigenic Mexican strain (CM 91-3, ctxAB-). Supernatant from those recombinant E. coli strains induced haemolysis, cell vacuolation and cytotoxicity. RFLP-PCR analysis revealed similarities in the hlyA gene from all strains tested. The HlyA-induced vacuolating effect is a widespread phenotype of epidemic V. cholerae O1 ElTor strains.

  18. Compressive strain induced enhancement in thermoelectric-power-factor in monolayer MoS2 nanosheet

    International Nuclear Information System (INIS)

    Dimple; Jena, Nityasagar; De Sarkar, Abir

    2017-01-01

    Strain and temperature induced tunability in the thermoelectric properties in monolayer MoS 2 (ML-MoS 2 ) has been demonstrated using density functional theory coupled to semi-classical Boltzmann transport theory. Compressive strain, in general and uniaxial compressive strain (along the zig-zag direction), in particular, is found to be most effective in enhancing the thermoelectric power factor, owing to the higher electronic mobility and its sensitivity to lattice compression along this direction. Variation in the Seebeck coefficient and electronic band gap with strain is found to follow the Goldsmid–Sharp relation. n-type doping is found to raise the relaxation time-scaled thermoelectric power factor higher than p-type doping and this divide widens with increasing temperature. The relaxation time-scaled thermoelectric power factor in optimally n-doped ML-MoS 2 is found to undergo maximal enhancement under the application of 3% uniaxial compressive strain along the zig-zag direction, when both the ( direct ) electronic band gap and the Seebeck coefficient reach their maximum, while the electron mobility drops down drastically from 73.08 to 44.15 cm 2 V −1 s −1 . Such strain sensitive thermoelectric responses in ML-MoS 2 could open doorways for a variety of applications in emerging areas in 2D-thermoelectrics, such as on-chip thermoelectric power generation and waste thermal energy harvesting. (paper)

  19. Micromechanical modeling of stress-induced strain in polycrystalline Ni–Mn–Ga by directional solidification

    International Nuclear Information System (INIS)

    Zhu, Yuping; Shi, Tao; Teng, Yao

    2015-01-01

    Highlights: • A micromechanical model of directional solidification Ni–Mn–Ga is developed. • The stress–strain curves in different directions are tested. • The martensite Young’s moduli in different directions are predicted. • The macro reorientation strains in different directions are investigated. - Abstract: Polycrystalline ferromagnetic shape memory alloy Ni–Mn–Ga produced by directional solidification possess unique properties. Its compressive stress–strain behaviors in loading–unloading cycle show nonlinear and anisotropic. Based on the self-consistent theory and thermodynamics principle, a micromechanical constitutive model of polycrystalline Ni–Mn–Ga by directional solidification is developed considering the generating mechanism of the macroscopic strain and anisotropy. Then, the stress induced strains at different angles to solidification direction are calculated, and the results agree well with the experimental data. The predictive curves of martensite Young’s modulus and macro reorientation strain in different directions are investigated. It may provide theoretical guidance for the design and use of ferromagnetic shape memory alloy

  20. Genomic characterization of a large outbreak of Legionella pneumophila serogroup 1 strains in Quebec City, 2012.

    Directory of Open Access Journals (Sweden)

    Simon Lévesque

    Full Text Available During the summer of 2012, a major Legionella pneumophila serogroup 1 outbreak occurred in Quebec City, Canada, which caused 182 declared cases of Legionnaire's disease and included 13 fatalities. Legionella pneumophila serogroup 1 isolates from 23 patients as well as from 32 cooling towers located in the vicinity of the outbreak were recovered for analysis. In addition, 6 isolates from the 1996 Quebec City outbreak and 4 isolates from patients unrelated to both outbreaks were added to allow comparison. We characterized the isolates using pulsed-field gel electrophoresis, sequence-based typing, and whole genome sequencing. The comparison of patients-isolated strains to cooling tower isolates allowed the identification of the tower that was the source of the outbreak. Legionella pneumophila strain Quebec 2012 was identified as a ST-62 by sequence-based typing methodology. Two new Legionellaceae plasmids were found only in the epidemic strain. The LVH type IV secretion system was found in the 2012 outbreak isolates but not in the ones from the 1996 outbreak and only in half of the contemporary human isolates. The epidemic strains replicated more efficiently and were more cytotoxic to human macrophages than the environmental strains tested. At least four Icm/Dot effectors in the epidemic strains were absent in the environmental strains suggesting that some effectors could impact the intracellular replication in human macrophages. Sequence-based typing and pulsed-field gel electrophoresis combined with whole genome sequencing allowed the identification and the analysis of the causative strain including its likely environmental source.

  1. Analysis of optical properties of strained semiconductor quantum dots for electromagnetically induced transparency

    DEFF Research Database (Denmark)

    Barettin, D.; Houmark-Nielsen, Jakob; Lassen, B.

    2010-01-01

    different k*p band structure models. In addition to the separation of the heavy and light holes due to the biaxial strain component, we observe a general reduction in the transition strengths due to energy crossings in the valence bands caused by strain and band mixing effects. We furthermore find a non......Using multiband k*p theory we study the size and geometry dependence on the slow light properties of conical semiconductor quantum dots. We find the V-type scheme for electromagnetically induced transparency (EIT) to be most favorable, and identify an optimal height and size for efficient EIT...... operation. In case of the ladder scheme, the existence of additional dipole allowed intraband transitions along with an almost equidistant energy level spacing adds additional decay pathways, which significantly impairs the EIT effect. We further study the influence of strain and band mixing comparing four...

  2. Strain-induced phase transition and electron spin-polarization in graphene spirals.

    Science.gov (United States)

    Zhang, Xiaoming; Zhao, Mingwen

    2014-07-16

    Spin-polarized triangular graphene nanoflakes (t-GNFs) serve as ideal building blocks for the long-desired ferromagnetic graphene superlattices, but they are always assembled to planar structures which reduce its mechanical properties. Here, by joining t-GNFs in a spiral way, we propose one-dimensional graphene spirals (GSs) with superior mechanical properties and tunable electronic structures. We demonstrate theoretically the unique features of electron motion in the spiral lattice by means of first-principles calculations combined with a simple Hubbard model. Within a linear elastic deformation range, the GSs are nonmagnetic metals. When the axial tensile strain exceeds an ultimate strain, however, they convert to magnetic semiconductors with stable ferromagnetic ordering along the edges. Such strain-induced phase transition and tunable electron spin-polarization revealed in the GSs open a new avenue for spintronics devices.

  3. Effect of lithographically-induced strain relaxation on the magnetic domain configuration in microfabricated epitaxially grown Fe81Ga19

    Science.gov (United States)

    Beardsley, R. P.; Parkes, D. E.; Zemen, J.; Bowe, S.; Edmonds, K. W.; Reardon, C.; Maccherozzi, F.; Isakov, I.; Warburton, P. A.; Campion, R. P.; Gallagher, B. L.; Cavill, S. A.; Rushforth, A. W.

    2017-02-01

    We investigate the role of lithographically-induced strain relaxation in a micron-scaled device fabricated from epitaxial thin films of the magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic patterning induces a magnetic anisotropy that competes with the magnetocrystalline and shape induced anisotropies to play a crucial role in stabilising a flux-closing domain pattern. We use magnetic imaging, micromagnetic calculations and linear elastic modelling to investigate a region close to the edges of an etched structure. This highly-strained edge region has a significant influence on the magnetic domain configuration due to an induced magnetic anisotropy resulting from the inverse magnetostriction effect. We investigate the competition between the strain-induced and shape-induced anisotropy energies, and the resultant stable domain configurations, as the width of the bar is reduced to the nanoscale range. Understanding this behaviour will be important when designing hybrid magneto-electric spintronic devices based on highly magnetostrictive materials.

  4. High-strain-induced deformation mechanisms in block-graft and multigraft copolymers

    KAUST Repository

    Schlegel, Ralf

    2011-12-13

    The molecular orientation behavior and structural changes of morphology at high strains for multigraft and block-graft copolymers based on polystyrene (PS) and polyisoprene (PI) were investigated during uniaxial monotonic loading via FT-IR and synchrotron SAXS. Results from FT-IR revealed specific orientations of PS and PI segments depending on molecular architecture and on the morphology, while structural investigations revealed a typical decrease in long-range order with increasing strain. This decrease was interpreted as strain-induced dissolution of the glassy blocks in the soft matrix, which is assumed to affect an additional enthalpic contribution (strain-induced mixing of polymer chains) and stronger retracting forces of the network chains during elongation. Our interpretation is supported by FT-IR measurements showing similar orientation of rubbery and glassy segments up to high strains. It also points to highly deformable PS domains. By synchrotron SAXS, we observed in the neo-Hookean region an approach of glassy domains, while at higher elongations the intensity of the primary reflection peak was significantly decreasing. The latter clearly verifies the assumption that the glassy chains are pulled out from the domains and are partly mixed in the PI matrix. Results obtained by applying models of rubber elasticity to stress-strain and hysteresis data revealed similar correlations between the softening behavior and molecular and morphological parameters. Further, an influence of the network modality was observed (random grafted branches). For sphere forming multigraft copolymers the domain functionality was found to be less important to achieve improved mechanical properties but rather size and distribution of the domains. © 2011 American Chemical Society.

  5. Influence of mechanically-induced dilatation on the shape memory behavior of amorphous polymers at large deformation

    Science.gov (United States)

    Hanzon, Drew W.; Lu, Haibao; Yakacki, Christopher M.; Yu, Kai

    2018-01-01

    In this study, we explore the influence of mechanically-induced dilatation on the thermomechanical and shape memory behavior of amorphous shape memory polymers (SMPs) at large deformation. The uniaxial tension, glass transition, stress relaxation and free recovery behaviors are examined with different strain levels (up to 340% engineering strain). A multi-branched constitutive model that incorporates dilatational effects on the polymer relaxation time is established and applied to assist in discussions and understand the nonlinear viscoelastic behaviors of SMPs. It is shown that the volumetric dilatation results in an SMP network with lower viscosity, faster relaxation, and lower Tg. The influence of the dilatational effect on the thermomechanical behaviors is significant when the polymers are subject to large deformation or in a high viscosity state. The dilation also increases the free recovery rate of SMP at a given recovery temperature. Even though the tested SMPs are far beyond their linear viscoelastic region when a large programming strain is applied, the free recovery behavior still follows the time-temperature superposition (TTSP) if the dilatational effect is considered during the transformation of time scales; however, if the programming strain is different, TTSP fails in predicting the recovery behavior of SMPs because the network has different entropy state and driving force during shape recovery. Since most soft active polymers are subject to large deformation in practice, this study provides a theoretical basis to better understand their nonlinear viscoelastic behaviors, and optimize their performance in engineering applications.

  6. A comparative investigation on strain induced crystallization for graphene and carbon nanotubes filled natural rubber composites

    Directory of Open Access Journals (Sweden)

    D. H. Fu

    2015-07-01

    Full Text Available Natural rubber containing graphene and carbon nanotubes (CNTs composites were prepared by ultrasonicallyassisted latex mixing. Natural rubber filled by both graphene and CNTs show significant enhanced tensile strength, while graphene exhibits a better reinforcing effect than CNTs. Strain-induced crystallization in natural rubber composites during stretching was determined by synchrotron wide-angle X-ray diffraction. With the addition of CNTs or graphene, the crystallization for natural rubber occurs at a lower strain compared to unfilled natural rubber, and the strain amplification effects were observed. The incorporation of graphene results in a faster strain-induced crystallization rate and a higher crystallinity compared to CNTs. The entanglement-bound rubber tube model was used to analyze the chain network structure and determine the network parameters of composites. The results show that the addition of graphene or CNTs has an influence on the molecular network structure and improves the contribution of entanglement to the conformational constraint, while graphene has a more marked effect than CNTs.

  7. Induced systemic resistance against Botrytis cinerea by Micromonospora strains isolated from root nodules

    Directory of Open Access Journals (Sweden)

    Pilar eMartínez-Hidalgo

    2015-09-01

    Full Text Available Micromonospora is a Gram positive bacterium that can be isolated from nitrogen fixing nodules from healthy leguminous plants, where they could be beneficial to the plant. Their plant growth promoting activity in legume and non-legume plants has been previously demonstrated. The present study explores the ability of Micromonospora strains to control fungal pathogens and to stimulate plant immunity. Micromonospora strains isolated from surface sterilized nodules of alfalfa showed in vitro antifungal activity against several pathogenic fungi. Moreover, root inoculation of tomato plants with these Micromonospora strains effectively reduced leaf infection by the fungal pathogen Botrytis cinerea, despite spatial separation between both microorganisms. This induced systemic resistance, confirmed in different tomato cultivars, is long lasting. Gene expression analyses evidenced that Micromonospora stimulates the plant capacity to activate defense mechanisms upon pathogen attack. The defensive response of tomato plants inoculated with Micromonospora spp. differs from that of non-inoculated plants, showing a stronger induction of jasmonate-regulated defenses when the plant is challenged with a pathogen. The hypothesis of jasmonates playing a key role in this defense priming effect was confirmed using defense-impaired tomato mutants, since the JA-deficient line def1 was unable to display a long term induced resistance upon Micromonospora spp. inoculation.In conclusion, nodule isolated Micromonospora strains should be considered excellent candidates as biocontrol agents as they combine both direct antifungal activity against plant pathogens and the ability to prime plant immunity.

  8. Strain-induced oxygen vacancies in ultrathin epitaxial CaMnO3 films

    Science.gov (United States)

    Chandrasena, Ravini; Yang, Weibing; Lei, Qingyu; Delgado-Jaime, Mario; de Groot, Frank; Arenholz, Elke; Kobayashi, Keisuke; Aschauer, Ulrich; Spaldin, Nicola; Xi, Xiaoxing; Gray, Alexander

    Dynamic control of strain-induced ionic defects in transition-metal oxides is considered to be an exciting new avenue towards creating materials with novel electronic, magnetic and structural properties. Here we use atomic layer-by-layer laser molecular beam epitaxy to synthesize high-quality ultrathin single-crystalline CaMnO3 films with systematically varying coherent tensile strain. We then utilize a combination of high-resolution soft x-ray absorption spectroscopy and bulk-sensitive hard x-ray photoemission spectroscopy in conjunction with first-principles theory and core-hole multiplet calculations to establish a direct link between the coherent in-plane strain and the oxygen-vacancy content. We show that the oxygen vacancies are highly mobile, which necessitates an in-situ-grown capping layer in order to preserve the original strain-induced oxygen-vacancy content. Our findings open the door for designing and controlling new ionically active properties in strongly-correlated transition-metal oxides.

  9. Strain-induced structural changes and chemical reactions. 1: Thermomechanical and kinetic models

    International Nuclear Information System (INIS)

    Levitas, V.I.; Nesterenko, V.F.; Meyers, M.A.

    1998-01-01

    Strain-induced chemical reactions were observed recently (Nesterenko et al) in experiments in the shear band in both Ti-Si and Nb-Si mixtures. Reactions can start in the solid state or after melting of at least one component. One of the aims is to find theoretically whether there are possible macroscopic mechanisms of mechanical intensification of the above and other chemical reactions due to plastic shear in the solid state. Continuum thermodynamical theory of structural changes with an athermal kinetics, which includes martensitic phase transformations, plastic strain-induced chemical reactions and polymorphic transformations, is developed at finite strains. The theory includes kinematics, criterion of structural change and extremum principle for determination of all unknown variable parameters for the case with neglected elastic strains. Thermodynamically consistent kinetic theory of thermally activated structural changes is suggested. The concept of the effective temperature is introduced which takes into account that temperature can vary significantly (on 1,000 K) during the chemical reactions under consideration. The theory will be applied in Part 2 of the paper for the description of chemical reactions in the shear band

  10. Large Eddy Simulations of Severe Convection Induced Turbulence

    Science.gov (United States)

    Ahmad, Nash'at; Proctor, Fred

    2011-01-01

    Convective storms can pose a serious risk to aviation operations since they are often accompanied by turbulence, heavy rain, hail, icing, lightning, strong winds, and poor visibility. They can cause major delays in air traffic due to the re-routing of flights, and by disrupting operations at the airports in the vicinity of the storm system. In this study, the Terminal Area Simulation System is used to simulate five different convective events ranging from a mesoscale convective complex to isolated storms. The occurrence of convection induced turbulence is analyzed from these simulations. The validation of model results with the radar data and other observations is reported and an aircraft-centric turbulence hazard metric calculated for each case is discussed. The turbulence analysis showed that large pockets of significant turbulence hazard can be found in regions of low radar reflectivity. Moderate and severe turbulence was often found in building cumulus turrets and overshooting tops.

  11. Biological consequences of ancient gene acquisition and duplication in the large genome soil bacterium, ""solibacter usitatus"" strain Ellin6076

    Energy Technology Data Exchange (ETDEWEB)

    Challacombe, Jean F [Los Alamos National Laboratory; Eichorst, Stephanie A [Los Alamos National Laboratory; Xie, Gary [Los Alamos National Laboratory; Kuske, Cheryl R [Los Alamos National Laboratory; Hauser, Loren [ORNL; Land, Miriam [ORNL

    2009-01-01

    Bacterial genome sizes range from ca. 0.5 to 10Mb and are influenced by gene duplication, horizontal gene transfer, gene loss and other evolutionary processes. Sequenced genomes of strains in the phylum Acidobacteria revealed that 'Solibacter usistatus' strain Ellin6076 harbors a 9.9 Mb genome. This large genome appears to have arisen by horizontal gene transfer via ancient bacteriophage and plasmid-mediated transduction, as well as widespread small-scale gene duplications. This has resulted in an increased number of paralogs that are potentially ecologically important (ecoparalogs). Low amino acid sequence identities among functional group members and lack of conserved gene order and orientation in the regions containing similar groups of paralogs suggest that most of the paralogs were not the result of recent duplication events. The genome sizes of cultured subdivision 1 and 3 strains in the phylum Acidobacteria were estimated using pulsed-field gel electrophoresis to determine the prevalence of the large genome trait within the phylum. Members of subdivision 1 were estimated to have smaller genome sizes ranging from ca. 2.0 to 4.8 Mb, whereas members of subdivision 3 had slightly larger genomes, from ca. 5.8 to 9.9 Mb. It is hypothesized that the large genome of strain Ellin6076 encodes traits that provide a selective metabolic, defensive and regulatory advantage in the variable soil environment.

  12. Tip-induced local strain on Mo S2/graphite detected by inelastic electron tunneling spectroscopy

    Science.gov (United States)

    Ko, Wonhee; Hus, Saban M.; Li, Xufan; Berlijn, Tom; Nguyen, Giang D.; Xiao, Kai; Li, An-Ping

    2018-03-01

    We report the detection of tip-induced local strain applied to the monolayer Mo S2 grown on a graphite substrate by scanning tunneling microscope. Monolayer Mo S2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Our results demonstrate a way to apply local mechanical strain and simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.

  13. Constitutive Model Of Graded Micro-Structure Obtained Via Strain Induced Phase Transformation

    CERN Document Server

    Ortwein, Rafał

    The literature review has been divided into three main sub-chapters. The first one is concentrated on the general information about stainless steels and their applications. It is important to perform a general overview and get an idea where the results of the present thesis could be applied. Description of all the brands of stainless steels, their microstructures and properties are important, as similar characteristics can be found in the newly created functionally graded structures. The second sub-chapter is an overview of the most important constitutive models and the experimental results for materials that undergo plastic strain induced phase transformation. Finally, the last one is devoted to functionally graded microstructures obtained via strain induced martensitic transformation – the subject of particular importance for the present thesis. As a general note, the literature review is organized mainly in a chronological order. In some cases similar publications or publications of the same Authors were...

  14. Aging enhances the vulnerability of mesenchymal stromal cells to uniaxial tensile strain-induced apoptosis.

    Science.gov (United States)

    McKayed, Katey; Prendergast, Patrick J; Campbell, Veronica A

    2016-02-08

    Mechanical priming can be employed in tissue engineering strategies to control the fate and differentiation pattern of mesenchymal stromal cells. This is relevant to regenerative medicine whereby mechanical cues can promote the regeneration of a specific tissue type from mesenchymal precursors. The ability of cells to respond to mechanical forces is dependent upon mechanotransduction pathways that involve membrane-associated proteins, such as integrins. During the aging process changes in the mechanotransduction machinery may influence how cells from aged individuals respond to mechanical priming. In this study mesenchymal stromal cells were prepared from young adult and aged rats and exposed to uniaxial tensile strain at 5% and 10% for 3 days, or 2.5% for 7 days. Application of 5% tensile strain had no impact on cell viability. In contrast, application of 10% tensile strain evoked apoptosis and the strain-induced apoptosis was significantly higher in the mesenchymal stromal cells prepared from the aged rats. In parallel to the age-related difference in cellular responsiveness to strain, an age-related decrease in expression of α2 integrin and actin, and enhanced lipid peroxidation was observed. This study demonstrates that mesenchymal stem cells from aged animals have an altered membrane environment, are more vulnerable to the pro-apoptotic effects of 10% tensile strain and less responsive to the pro-osteogenic effects of 2.5% tensile strain. Thus, it is essential to consider how aged cells respond to mechanical stimuli in order to identify optimal mechanical priming strategies that minimise cell loss, particularly if this approach is to be applied to an aged population. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Robert, C., E-mail: cedric.robert@insa-rennes.fr, E-mail: cedric.robert@tyndall.ie; Pedesseau, L.; Cornet, C.; Jancu, J.-M.; Even, J.; Durand, O. [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France); Nestoklon, M. O. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pereira da Silva, K. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, Fortaleza–CE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goñi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)

    2014-01-06

    The nature of the ground optical transition in an (In,Ga)As/GaP quantum dot is thoroughly investigated through a million atoms supercell tight-binding simulation. Precise quantum dot morphology is deduced from previously reported scanning-tunneling-microscopy images. The strain field is calculated with the valence force field method and has a strong influence on the confinement potentials, principally, for the conduction band states. Indeed, the wavefunction of the ground electron state is spatially confined in the GaP matrix, close to the dot apex, in a large tensile strain region, having mainly Xz character. Photoluminescence experiments under hydrostatic pressure strongly support the theoretical conclusions.

  16. The Investigation on Strain Strengthening Induced Martensitic Phase Transformation of Austenitic Stainless Steel: A Fundamental Research for the Quality Evaluation of Strain Strengthened Pressure Vessel

    Science.gov (United States)

    Li, Bo; Cai Ren, Fa; Tang, Xiao Ying

    2018-03-01

    The manufacture of pressure vessels with austenitic stainless steel strain strengthening technology has become an important technical means for the light weight of cryogenic pressure vessels. In the process of increasing the strength of austenitic stainless steel, strain can induce the martensitic phase transformation in austenite phase. There is a quantitative relationship between the transformation quantity of martensitic phase and the basic mechanical properties. Then, the martensitic phase variables can be obtained by means of detection, and the mechanical properties and safety performance are evaluated and calculated. Based on this, the quantitative relationship between strain hardening and deformation induced martensite phase content is studied in this paper, and the mechanism of deformation induced martensitic transformation of austenitic stainless steel is detailed.

  17. Seasonal variations of seismicity and geodetic strain in the Himalaya induced by surface hydrology

    OpenAIRE

    Bettinelli, Pierre; Avouac, Jean-Philippe; Flouzat, Mireille; Bollinger, Laurent; Ramillien, Guillaume; Rajaure, Sudhir; Sapkota, Som

    2008-01-01

    One way to probe earthquake nucleation processes and the relation between stress buildup and seismicity is to analyze the sensitivity of seismicity to stress perturbations. Here, we report evidence for seasonal strain and stress (~ 2–4 kPa) variations in the Nepal Himalaya, induced by water storage variations which correlate with seasonal variations of seismicity. The seismicity rate is twice as high in the winter as in the summer, and correlates with stress rate variations. We infer ~ 10–20 ...

  18. Large-scale bioreactor production of the herbicide-degrading Aminobacter sp. strain MSH1

    DEFF Research Database (Denmark)

    Schultz-Jensen, Nadja; Knudsen, Berith Elkær; Frkova, Zuzana

    2014-01-01

    The Aminobacter sp. strain MSH1 has potential for pesticide bioremediation because it degrades the herbicide metabolite 2,6-dichlorobenzamide (BAM). Production of the BAM-degrading bacterium using aerobic bioreactor fermentation was investigated. A mineral salt medium limited for carbon and with ......The Aminobacter sp. strain MSH1 has potential for pesticide bioremediation because it degrades the herbicide metabolite 2,6-dichlorobenzamide (BAM). Production of the BAM-degrading bacterium using aerobic bioreactor fermentation was investigated. A mineral salt medium limited for carbon...... and with an element composition similar to the strain was generated. The optimal pH and temperature for strain growth were determined using shaker flasks and verified in bioreactors. Glucose, fructose, and glycerol were suitable carbon sources for MSH1 (μ =0.1 h−1); slower growth was observed on succinate and acetic...... acid (μ =0.01 h−1). Standard conditions for growth of theMSH1 strain were defined at pH 7 and 25 °C, with glucose as the carbon source. In bioreactors (1 and 5 L), the specific growth rate of MSH1 increased from μ =0.1 h−1 on traditional mineral salt medium to μ =0.18 h−1 on the optimized mineral salt...

  19. Comparative genome analysis identifies two large deletions in the genome of highly-passaged attenuated Streptococcus agalactiae strain YM001 compared to the parental pathogenic strain HN016.

    Science.gov (United States)

    Wang, Rui; Li, Liping; Huang, Yan; Luo, Fuguang; Liang, Wanwen; Gan, Xi; Huang, Ting; Lei, Aiying; Chen, Ming; Chen, Lianfu

    2015-11-04

    Streptococcus agalactiae (S. agalactiae), also known as group B Streptococcus (GBS), is an important pathogen for neonatal pneumonia, meningitis, bovine mastitis, and fish meningoencephalitis. The global outbreaks of Streptococcus disease in tilapia cause huge economic losses and threaten human food hygiene safety as well. To investigate the mechanism of S. agalactiae pathogenesis in tilapia and develop attenuated S. agalactiae vaccine, this study sequenced and comparatively analyzed the whole genomes of virulent wild-type S. agalactiae strain HN016 and its highly-passaged attenuated strain YM001 derived from tilapia. We performed Illumina sequencing of DNA prepared from strain HN016 and YM001. Sequencedreads were assembled and nucleotide comparisons, single nucleotide polymorphism (SNP) , indels were analyzed between the draft genomes of HN016 and YM001. Clustered regularly interspaced short palindromic repeats (CRISPRs) and prophage were detected and analyzed in different S. agalactiae strains. The genome of S. agalactiae YM001 was 2,047,957 bp with a GC content of 35.61 %; it contained 2044 genes and 88 RNAs. Meanwhile, the genome of S. agalactiae HN016 was 2,064,722 bp with a GC content of 35.66 %; it had 2063 genes and 101 RNAs. Comparative genome analysis indicated that compared with HN016, YM001 genome had two significant large deletions, at the sizes of 5832 and 11,116 bp respectively, resulting in the deletion of three rRNA and ten tRNA genes, as well as the deletion and functional damage of ten genes related to metabolism, transport, growth, anti-stress, etc. Besides these two large deletions, other ten deletions and 28 single nucleotide variations (SNVs) were also identified, mainly affecting the metabolism- and growth-related genes. The genome of attenuated S. agalactiae YM001 showed significant variations, resulting in the deletion of 10 functional genes, compared to the parental pathogenic strain HN016. The deleted and mutated functional genes all

  20. Nucleation and evolution of strain-induced martensitic (b.c.c.) embryos and substructure in stainless steel: a transmission electron microscope study

    International Nuclear Information System (INIS)

    Staudhammer, K.P.; Hecker, S.S.; Murr, L.E.

    1983-01-01

    The deformation of type 304 stainless steel produces a preponderance of strain-induced /chi/ (b.c.c.) martensite, which nucleates as stable embryos at micro-shear band or twin-fault intersections as proposed by Olson and Cohen. The two intersecting micro-shear bands must have a specific defect (fault-displacement) structure, and for stable martensite embryos to form requires a minimal micro-shear band thickness ranging from 50-70 A. The critical nature of nucleation is influenced by the local temperature and strain. The structure, geometry, and morphology of strain-induced martensite embryos is essentially invariant regardless of the strain rate, strain state or temperature. Larger volume fractions of martensite evolve at large strains (greater than or equal to 20%) as a result of embryo coalescence to produce a blocky-type morphology. Martensite embryos and coalesced volume elements of /chi/ are frequently characterized by an irregular non-homogeneous distribution of smaller b.c.c. regimes which result from the irregular satisfaction of the necessary and specific fault-displacement requirements within a larger intersection volume

  1. Detection and characterisation of Yersinia enterocolitica strains in cold-stored carcasses of large game animals in Poland.

    Science.gov (United States)

    Bancerz-Kisiel, Agata; Socha, Piotr; Szweda, Wojciech

    2016-02-01

    Yersinia enterocolitica is an important foodborne pathogen. The aim of the present study was to identify the bioserotypes and virulence markers of Y.enterocolitica strains isolated from three different anatomical regions of cold-stored carcasses of large game animals intended for human consumption. Y.enterocolitica strains were found in 12/20 (60%) of the roe deer carcasses examined, 7/16 (43.8%) of red deer carcasses and 11/20 (55%) of wild boar carcasses. Of the 52 Y.enterocolitica strains, 19 were isolated from the perineum, followed by 17 strains from the peritoneum of the longissimus dorsi muscle and 16 from the tonsils. Only one strain was isolated from warm culture. Bioserotype 1A/NI was the most commonly found and was detected in 29/52 isolates. All isolates contained amplicons corresponding to ystB gene fragments. The relatively high degree of carcass contamination with Y.enterocolitica is of concern due to the growing popularity of game meat with consumers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Associations between Job Strain and Arterial Stiffness: A Large Survey among Enterprise Employees from Thailand

    Directory of Open Access Journals (Sweden)

    Orawan Kaewboonchoo

    2018-04-01

    Full Text Available As an intermediate endpoint to cardiovascular disease, arterial stiffness has received much attention recently. So far, the research on work stress and arterial stiffness is still sparse and inconsistent, and no investigations on work stress and cardiovascular health among the Thai working population have been reported. Therefore, we conducted an epidemiological study among 2141 Thai enterprise employees (858 men and 1283 women who were free from any diagnosed cardiovascular disease. Work stress was measured using Karasek’s Job Demand–Control model for job strain (a combination of high demand and low control. Arterial stiffness was evaluated by a non-invasive approach using pulse-wave analysis based on a finger photoplethysmogram. Multivariable linear regression was applied to examine associations between job strain and arterial stiffness. In men, job strain was significantly associated with arterial stiffness (β  =  0.078, 95% confidence interval  =  0.026 to 0.130, after accounting for sociodemographic, behavioral, dietary and biomedical factors. However, the association in women was not significant. As the first study in Thailand on work stress and cardiovascular risk, we found that job strain might be an important risk factor for cardiovascular disease among Thai working men. Further studies with longitudinal design are warranted.

  3. Large-strain optical fiber sensing and real-time FEM updating of steel structures under the high temperature effect

    International Nuclear Information System (INIS)

    Huang, Ying; Fang, Xia; Xiao, Hai; Bevans, Wesley James; Chen, Genda; Zhou, Zhi

    2013-01-01

    Steel buildings are subjected to fire hazards during or immediately after a major earthquake. Under combined gravity and thermal loads, they have non-uniformly distributed stiffness and strength, and thus collapse progressively with large deformation. In this study, large-strain optical fiber sensors for high temperature applications and a temperature-dependent finite element model updating method are proposed for accurate prediction of structural behavior in real time. The optical fiber sensors can measure strains up to 10% at approximately 700 °C. Their measurements are in good agreement with those from strain gauges up to 0.5%. In comparison with the experimental results, the proposed model updating method can reduce the predicted strain errors from over 75% to below 20% at 800 °C. The minimum number of sensors in a fire zone that can properly characterize the vertical temperature distribution of heated air due to the gravity effect should be included in the proposed model updating scheme to achieve a predetermined simulation accuracy. (paper)

  4. Effects of gauge volume on pseudo-strain induced in strain measurement using time-of-flight neutron diffraction

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Harjo, Stefanus; Abe, Jun; Xu, Pingguang; Aizawa, Kazuya; Akita, Koichi

    2013-01-01

    Spurious or pseudo-strains observed in time-of-flight (TOF) neutron diffraction due to neutron attenuation, surface-effects and a strain distribution within the gauge volume were investigated. Experiments were carried out on annealed and bent ferritic steel bars to test these effects. The most representative position in the gauge volume corresponds to the neutron-weighted center of gravity (ncog), which takes into account variations in intensity within the gauge volume due to neutron attenuation and/or absence of material in the gauge volume. The average strain in the gauge volume was observed to be weighted towards the ncog position but following an increase in the size of the gauge volume the weighted average strain was changed because of the change in the ncog position when a strain gradient appeared within the gauge volume. On the other hand, typical pseudo-strains, which are well known, did appear in through-surface strain measurements when the gauge volume was incompletely filled by the sample. Tensile pseudo-strains due to the surface-effect increased near the sample surface and exhibited a similar trend regardless of the size of the gauge volume, while the pseudo-strains increased faster for the smaller gauge volume. Furthermore, a pseudo-strain due to a change in the ncog position was observed even when the gauge volume was perfectly filled in the sample, and it increased with an increase in the size of the gauge volume. These pseudo-strains measured were much larger than those simulated by the conventional modeling, whereas they were simulated by taking into account an incident neutron beam divergence additionally in the model. Therefore, the incident divergence of the incident neutron beam must be carefully designed to avoid pseudo-strains in time-of-flight neutron diffractometry

  5. The demonstration of nonlinear analytic model for the strain field induced by thermal copper filled TSVs (through silicon via

    Directory of Open Access Journals (Sweden)

    M. H. Liao

    2013-08-01

    Full Text Available The thermo-elastic strain is induced by through silicon vias (TSV due to the difference of thermal expansion coefficients between the copper (∼18 ppm/ °C and silicon (∼2.8 ppm/ °C when the structure is exposed to a thermal ramp budget in the three dimensional integrated circuit (3DIC process. These thermal expansion stresses are high enough to introduce the delamination on the interfaces between the copper, silicon, and isolated dielectric. A compact analytic model for the strain field induced by different layouts of thermal copper filled TSVs with the linear superposition principle is found to have large errors due to the strong stress interaction between TSVs. In this work, a nonlinear stress analytic model with different TSV layouts is demonstrated by the finite element method and the analysis of the Mohr's circle. The characteristics of stress are also measured by the atomic force microscope-raman technique with nanometer level space resolution. The change of the electron mobility with the consideration of this nonlinear stress model for the strong interactions between TSVs is ∼2–6% smaller in comparison with those from the consideration of the linear stress superposition principle only.

  6. Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

    International Nuclear Information System (INIS)

    Liu, Taixiang; Gong, Xinglong; Xu, Yangguang; Pang, Haoming; Xuan, Shouhu

    2014-01-01

    A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magneto-induced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m −1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP. (paper)

  7. EBSD-based techniques for characterization of microstructural restoration processes during annealing of metals deformed to large plastic strains

    DEFF Research Database (Denmark)

    Godfrey, A.; Mishin, Oleg; Yu, Tianbo

    2012-01-01

    Some methods for quantitative characterization of the microstructures deformed to large plastic strains both before and after annealing are discussed and illustrated using examples of samples after equal channel angular extrusion and cold-rolling. It is emphasized that the microstructures...... in such deformed samples exhibit a heterogeneity in the microstructural refinement by high angle boundaries. Based on this, a new parameter describing the fraction of regions containing predominantly low angle boundaries is introduced. This parameter has some advantages over the simpler high angle boundary...... on mode of the distribution of dislocation cell sizes is outlined, and it is demonstrated how this parameter can be used to investigate the uniformity, or otherwise, of the restoration processes occurring during annealing of metals deformed to large plastic strains. © (2012) Trans Tech Publications...

  8. Intestinal metaplasia induced by x-irradiation in different strains of rats

    International Nuclear Information System (INIS)

    Watanabe, Hiromitsu; Naito, Masashi; Kawashima, Kengo; Ito, Akihiro

    1985-01-01

    Attempts were made to examine strain differences in the susceptibility of rats to intestinal metaplasia induced by X-irradiation. The gastric regions of 4 inbred male rats (SHR, F344, WKY, and LEW strains) in 5-week-old and 2 random bred male rats (SD, and WIS strains) were irradiated with a total dose of 20 Gy X-ray given in two equal fractions separated by three days. Upon sacrifice at 6 months after the last irradiation, the number of intestinal metaplastic crypts with positive reaction to alkaline phosphatase (ALP) appeared highest in the SHR and lowest in the WIS rats. Morphologically, the number of crypts with intestinal metaplasia in whole glandular stomachs of SHR, WIS, F344, and SD rats were higher than those in WKY and LEW rats. In the pyloric gland, it was highest in WIS rats, while in the fundic gland it was highest in SHR rats. The results show that the appearance and location of intestinal metaplasia by X-irradiation are greatly influenced by the strain of the rat. (author)

  9. Electric field-induced valley degeneracy lifting in uniaxial strained graphene: Evidence from magnetophonon resonance

    Science.gov (United States)

    Assili, Mohamed; Haddad, Sonia; Kang, Woun

    2015-03-01

    A double peak structure in the magnetophonon resonance (MPR) spectrum of uniaxial strained graphene, under crossed electric and magnetic fields, is predicted. We focus on the Γ point optical phonon modes coupled to the inter-Landau level transitions 0 ⇆±1 where MPR is expected to be more pronounced at high magnetic field. We derive the frequency shifts and the broadenings of the longitudinal and transverse optical phonon modes taking into account the effect of the strain modified electronic spectrum on the electron-phonon coupling. We show that the MPR line for a given phonon mode acquires a double peak structure originating from the twofold valley degeneracy lifting. The latter is due to the different Landau level spacings in the two Dirac valleys resulting from the simultaneous action of the inplane electric field and the strain-induced Dirac cone tilt. We discuss the role of some key parameters such as disorder, strain, doping, and electric field amplitude on the emergence of the double peak structure.

  10. Strain-Induced Pseudo--Magnetic Fields in Graphene: MegaGauss in Nanobubbles

    Science.gov (United States)

    Levy, Niv

    2011-03-01

    Recent theoretical proposals suggest that strain can be used to modify graphene electronic states through the creation of a pseudo--magnetic field. This effect is unique to graphene because of its massless Dirac fermion-like band structure and particular lattice symmetry (C3v). Scanning tunneling microscopy shows that graphene grown on a platinum (111) surface forms nanobubbles, which are highly strained due to thermal expansion mismatch between the film and the substrate. We find that scanning tunneling spectroscopy measurements of these nanobubbles exhibit Landau levels that form in the presence of strain-induced pseudo--magnetic fields greater than 300 Tesla. This demonstration of enormous pseudo--magnetic fields opens the door to both the study of charge carriers in previously inaccessible high magnetic field regimes and deliberate mechanical control over electronic structure in graphene or so-called ``strain engineering''. In collaboration with S. A. Burke ,2 , K. L. Meaker 2 , M. Panlasigui 2 , A. Zettl 2,3 , F. Guinea 4 , A. H. Castro Neto 5 and M. F. Crommie 2,3 . 1. Present address: Department of Physics and Astronomy and Department of Chemistry, University of British Columbia, Vancouver, BC V6T 121, Canada. 2. Department of Physics, University of California, Berkeley, CA 94720, USA. 3. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 4. Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid 28049, Spain. 5. Department of Physics, Boston University, Boston, MA 02215, USA.

  11. Genetic analysis of γ-ray induced W-translocation strain on Bombyx nori

    International Nuclear Information System (INIS)

    Onuma, Akio; Murakami, Akio

    1976-01-01

    In the process of analyzing a γ-ray induced mutant of Bombyx nori oo cyte, new type translocation strains of W chromosomes and No.5 chromosomes were detected. The constitution of their translocated chromosomes was assumed to be Z/(W-V) + sup(pe)-V + sup(oc)/v. Owing to such chromosome constitution, it was considered that non-disjunction was induced at meiosis, and Z/(W-V) + sup(pe)/V, Z/(W-V) + sup(pe), V/V were produced besides Z/(W-V) + sup(pe)-V + sup(oc)/V in the female chromosomes (gene) of the next progeny, while V/V and Z/Z, V + sup(oc)/V were produced besides Z/Z, V/V in male. Death of some male eggs in this translocation strain was also observed. No dissociated individual of translocated chromosomes was segregated in the next progeny of the female moth with Z/(W-V) + sup(pe), V/V chromosome constitution and the marker stock male moth, while a few dissociated individuals appeared in the next progeny of Z/(W-V) + sup(pe)-V + sup(oc)/V female moth group. This fact seemed to be resulted from the complicated translocated chromosome constitution of the translocation strain. (Kobatake, H.)

  12. Elasto-optics in double-coated optical fibers induced by axial strain and hydrostatic pressure.

    Science.gov (United States)

    Yang, Yu-Ching; Lee, Haw-Long; Chou, Huann-Ming

    2002-04-01

    Stresses, microbending loss, and refractive-index changes induced simultaneously by axial strain and hydrostatic pressure in double-coated optical fibers are analyzed. The lateral pressure and normal stresses in the optical fiber, primary coating, and secondary coating are derived. Also presented are the microbending loss and refractive-index changes in the glass fiber. The normal stresses are affected by axial strain, hydrostatic pressure, material properties, and thickness of the primary and secondary coatings. It is found that microbending loss decreases with increasing thickness, the Young's modulus, and the Poisson's ratio of the secondary coating but increases with the increasing Young's modulus and Poisson's ratio of the primary coating. Similarly, changes in refractive index in the glass fiber decrease with the increasing Young's modulus and Poisson's ratio of the secondary coating but increase with the increasing Young's modulus and Poisson's ratio of the primary coating. Therefore, to minimize microbending loss induced simultaneously by axial strain and hydrostatic pressure in the glass fiber, the polymeric coatings should be suitably selected. An optimal design procedure is also indicated.

  13. Numerical and experimental evaluation of residual strains induced by pulsed laser welding

    International Nuclear Information System (INIS)

    Touvrey, C.; Bruyere, V.; Namy, P.

    2014-01-01

    The aim of the present study is to compare the residual strains induced by different welding processes during the assembly of two Ti6Al4V thin sheets. Several welding configurations and two means (pulsed laser and continuous one) are tested. The first part of the study intends to experimentally quantify strains induced by laser-matter interaction when one of the plates can freely bend. In this configuration the residual stresses are minimum, and consequently the strains measurement constitute a good indicator of the mechanical evolution. The displacements are in-situ reported thanks to a mechanical sensor. The second part of the study is dedicated to the numerical modeling of the processes. Unfortunately, the model is not completely predictive and appears to be oversimplified to describe the measured distortion. As it appears difficult to model the laser-matter interaction (especially in the case of many impacts recovering), we have adopted an equivalent approach to simulate the thermal evolution within the work pieces. An optimization procedure has been developed to determine an equivalent thermal flux, which leads to a melted zone shape in good agreement with experimental evaluations. The thermo-mechanical problem is computed by means of the finite elements software COMSOL Multiphysics. The results are compared to experimental data (displacement measurements) throughout the complete simulation. We plan to apply the complete model for more complex geometries, involving the generation of residual stresses. (authors)

  14. Strain-dependent sex differences in the effects of alcohol on cocaine-induced taste aversions.

    Science.gov (United States)

    Jones, Jermaine D; Busse, Gregory D; Riley, Anthony L

    2006-04-01

    Research using the conditioned taste aversion procedure has reported that a cocaine/alcohol combination induces a significantly stronger taste aversion than either cocaine or alcohol alone. These findings suggest that the co-administration of alcohol intensifies the aversive effects of cocaine. Although the behavioral interaction of cocaine and alcohol is well established, little is known about how the effects of this drug combination might be modulated by a variety of subject variables. The current investigation addressed this by assessing if the ability of alcohol to potentiate cocaine-induced taste aversions is dependent upon the strain and/or sex of the subject. In this series of studies, male and female rats of Long-Evans (Experiment 1) and Sprague-Dawley (Experiment 2) descent were given limited access to a novel saccharin solution to drink and were then injected with either vehicle, cocaine (20 mg/kg), alcohol (0.56 g/kg) or the alcohol/cocaine combination. This procedure was repeated every fourth day for a total of four conditioning trials. All subjects were then compared on an Aversion Test that followed the fourth conditioning cycle. In three of the groups tested (male Long-Evans; male and female Sprague-Dawley), cocaine induced a significant taste aversion that was unaffected by the co-administration of alcohol. However, in female Long-Evans subjects, the addition of alcohol significantly strengthened the avoidance of the saccharin solution. Although the effects of alcohol on cocaine-induced taste aversions are dependent upon an interaction of sex and strain, the basis for this SexxStrain interaction is not known. That such an interaction is evident suggests that attention to such factors in assessing the effects of drug combinations is important to understanding the likelihood of the use and abuse of such drugs.

  15. Rapid MALDI-TOF Mass Spectrometry Strain Typing during a Large Outbreak of Shiga-Toxigenic Escherichia coli

    Science.gov (United States)

    Christner, Martin; Trusch, Maria; Rohde, Holger; Kwiatkowski, Marcel; Schlüter, Hartmut; Wolters, Manuel; Aepfelbacher, Martin; Hentschke, Moritz

    2014-01-01

    Background In 2011 northern Germany experienced a large outbreak of Shiga-Toxigenic Escherichia coli O104:H4. The large amount of samples sent to microbiology laboratories for epidemiological assessment highlighted the importance of fast and inexpensive typing procedures. We have therefore evaluated the applicability of a MALDI-TOF mass spectrometry based strategy for outbreak strain identification. Methods Specific peaks in the outbreak strain’s spectrum were identified by comparative analysis of archived pre-outbreak spectra that had been acquired for routine species-level identification. Proteins underlying these discriminatory peaks were identified by liquid chromatography tandem mass spectrometry and validated against publicly available databases. The resulting typing scheme was evaluated against PCR genotyping with 294 E. coli isolates from clinical samples collected during the outbreak. Results Comparative spectrum analysis revealed two characteristic peaks at m/z 6711 and m/z 10883. The underlying proteins were found to be of low prevalence among genome sequenced E. coli strains. Marker peak detection correctly classified 292 of 293 study isolates, including all 104 outbreak isolates. Conclusions MALDI-TOF mass spectrometry allowed for reliable outbreak strain identification during a large outbreak of Shiga-Toxigenic E. coli. The applied typing strategy could probably be adapted to other typing tasks and might facilitate epidemiological surveys as part of the routine pathogen identification workflow. PMID:25003758

  16. Mice: progesterone and the regulation of strain differences in pregnancy-induced nest building.

    Science.gov (United States)

    Broida, J; Svare, B

    1983-12-01

    Pregnant DBA/2J females built significantly larger and more completely enclosed nests than did pregnant C57BL/6J mice. This strain difference was restricted to the last half of gestation and was not observed during either the virgin state or lactation. Genotype-based differences in pregnancy-induced nest building were not related to circulating levels of progesterone (P), core temperature, or body weight. Exposure to supplemented P during pregnancy elevated nest building exhibited by pregnant C57BL females but did not induce DBA-like levels of the behavior. Also, virgin DBA females built larger nests in response to P than did C57BL females. These findings suggest that differences in the sensitivity of central neural tissue to steroid hormones may account for genotypically determined variation in patterns of pregnancy-induced nest building.

  17. Analysis of mutagenic effects induced by carbon beams at different LET in a red yeast strain

    International Nuclear Information System (INIS)

    Sun Haining; Wang Jufang; Ma Shuang; Lu Dong; Wu Xin; Li Wenjian

    2011-01-01

    To evaluate inactive and mutagenic effects of carbon beam at different LET, the inactivation cross section and mutation cross section induced by carbon beams of different LET values were investigated in a red yeast strain Rhodotorula glutinis AY 91015. It was found that the maximum inactivation cross section of 4.37μm 2 , which was very close to the average nucleus cross section, was at LET of 120.0 keV/μm. The maximum mutation cross section was at LET of 96.0 keV/μm. Meanwhile, the highest mutagenicity of carbon ion was found around 58.2 keV/μm. It implied that the most efficient LET to induce mutation in survival yeasts was 58.2 keV/μm, which corresponded to energy of 35 MeV/u carbon beam. The most effective carbon beam to induce inactivation and mutation located at different energy region. (authors)

  18. Optimization of laccase production by two strains of Ganoderma lucidum using phenolic and metallic inducers

    Directory of Open Access Journals (Sweden)

    Francisco Kuhar

    Full Text Available Ganoderma lucidum (Curtis P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.

  19. Evolution behavior of nanohardness after thermal-aging and hydrogen-charging on austenite and strain-induced martensite in pre-strained austenitic stainless steel

    Science.gov (United States)

    Zheng, Yuanyuan; Zhou, Chengshuang; Hong, Yuanjian; Zheng, Jinyang; Zhang, Lin

    2018-05-01

    Nanoindentation has been used to study the effects of thermal-aging and hydrogen on the mechanical property of the metastable austenitic stainless steel. Thermal-aging at 473 K decreases the nanohardness of austenite, while it increases the nanohardness of strain-induced ɑ‧ martensite. Hydrogen-charging at 473 K increases the nanohardness of austenite, while it decreases the nanohardness of strain-induced ɑ‧ martensite. The opposite effect on austenite and ɑ‧ martensite is first found in the same pre-strained sample. This abnormal evolution behavior of hardness can be attributed to the interaction between dislocation and solute atoms (carbon and hydrogen). Carbon atoms are difficult to move and redistribute in austenite compared with ɑ‧ martensite. Therefore, the difference in the diffusivity of solute atoms between austenite and ɑ‧ martensite may result in the change of hardness.

  20. Storm induced large scale TIDs observed in GPS derived TEC

    Directory of Open Access Journals (Sweden)

    C. Borries

    2009-04-01

    Full Text Available This work is a first statistical analysis of large scale traveling ionospheric disturbances (LSTID in Europe using total electron content (TEC data derived from GNSS measurements. The GNSS receiver network in Europe is dense enough to map the ionospheric perturbation TEC with high horizontal resolution. The derived perturbation TEC maps are analysed studying the effect of space weather events on the ionosphere over Europe.

    Equatorward propagating storm induced wave packets have been identified during several geomagnetic storms. Characteristic parameters such as velocity, wavelength and direction were estimated from the perturbation TEC maps. Showing a mean wavelength of 2000 km, a mean period of 59 min and a phase speed of 684 ms−1 in average, the perturbations are allocated to LSTID. The comparison to LSTID observed over Japan shows an equal wavelength but a considerably faster phase speed. This might be attributed to the differences in the distance to the auroral region or inclination/declination of the geomagnetic field lines.

    The observed correlation between the LSTID amplitudes and the Auroral Electrojet (AE indicates that most of the wave like perturbations are exited by Joule heating. Particle precipitation effects could not be separated.

  1. Storm induced large scale TIDs observed in GPS derived TEC

    Directory of Open Access Journals (Sweden)

    C. Borries

    2009-04-01

    Full Text Available This work is a first statistical analysis of large scale traveling ionospheric disturbances (LSTID in Europe using total electron content (TEC data derived from GNSS measurements. The GNSS receiver network in Europe is dense enough to map the ionospheric perturbation TEC with high horizontal resolution. The derived perturbation TEC maps are analysed studying the effect of space weather events on the ionosphere over Europe. Equatorward propagating storm induced wave packets have been identified during several geomagnetic storms. Characteristic parameters such as velocity, wavelength and direction were estimated from the perturbation TEC maps. Showing a mean wavelength of 2000 km, a mean period of 59 min and a phase speed of 684 ms−1 in average, the perturbations are allocated to LSTID. The comparison to LSTID observed over Japan shows an equal wavelength but a considerably faster phase speed. This might be attributed to the differences in the distance to the auroral region or inclination/declination of the geomagnetic field lines. The observed correlation between the LSTID amplitudes and the Auroral Electrojet (AE indicates that most of the wave like perturbations are exited by Joule heating. Particle precipitation effects could not be separated.

  2. Failure of orally administered attenuated goose parvovirus strain B to induce a humoral immune response in adult geese.

    Science.gov (United States)

    Kisary, J; Kelemen, M

    1981-01-01

    Two-month-old geese responded with the production of virus neutralising antibodies against virulent goose parvovirus strain B administered either per os or intramuscularly. They were shedding the virus within a short period after exposure. Humoral immune response in geese of the same age was induced by the attenuated goose parvovirus strain B only by intramuscular injection but not with per os administration.

  3. Largely Tunable Band Structures of Few-Layer InSe by Uniaxial Strain.

    Science.gov (United States)

    Song, Chaoyu; Fan, Fengren; Xuan, Ningning; Huang, Shenyang; Zhang, Guowei; Wang, Chong; Sun, Zhengzong; Wu, Hua; Yan, Hugen

    2018-01-31

    Because of the strong quantum confinement effect, few-layer γ-InSe exhibits a layer-dependent band gap, spanning the visible and near infrared regions, and thus recently has been drawing tremendous attention. As a two-dimensional material, the mechanical flexibility provides an additional tuning knob for the electronic structures. Here, for the first time, we engineer the band structures of few-layer and bulk-like InSe by uniaxial tensile strain and observe a salient shift of photoluminescence peaks. The shift rate of the optical gap is approximately 90-100 meV per 1% strain for four- to eight-layer samples, which is much larger than that for the widely studied MoS 2 monolayer. Density functional theory calculations well reproduce the observed layer-dependent band gaps and the strain effect and reveal that the shift rate decreases with the increasing layer number for few-layer InSe. Our study demonstrates that InSe is a very versatile two-dimensional electronic and optoelectronic material, which is suitable for tunable light emitters, photodetectors, and other optoelectronic devices.

  4. Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV) Aided Photogrammetry

    Science.gov (United States)

    Ong, Wern Hann; Chiu, Wing Kong; Kuen, Thomas; Kodikara, Jayantha

    2017-01-01

    Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM) of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV) mounted with a digital camera and a global positioning system (GPS) tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM) for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures. PMID:28788081

  5. Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV) Aided Photogrammetry.

    Science.gov (United States)

    Ong, Wern Hann; Chiu, Wing Kong; Kuen, Thomas; Kodikara, Jayantha

    2017-07-28

    Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM) of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV) mounted with a digital camera and a global positioning system (GPS) tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM) for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures.

  6. Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV Aided Photogrammetry

    Directory of Open Access Journals (Sweden)

    Wern Hann Ong

    2017-07-01

    Full Text Available Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV mounted with a digital camera and a global positioning system (GPS tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures.

  7. Commercial Biocides Induce Transfer of Prophage Φ13 from Human Strains of Staphylococcus aureus to Livestock CC398

    Directory of Open Access Journals (Sweden)

    Yuanyue Tang

    2017-12-01

    Full Text Available Human strains of Staphylococcus aureus commonly carry the bacteriophage ΦSa3 that encodes immune evasion factors. Recently, this prophage has been found in livestock-associated, methicillin resistant S. aureus (MRSA CC398 strains where it may promote human colonization. Here, we have addressed if exposure to biocidal products induces phage transfer, and find that during co-culture, Φ13 from strain 8325, belonging to ΦSa3 group, is induced and transferred from a human strain to LA-MRSA CC398 when exposed to sub-lethal concentrations of commercial biocides containing hydrogen peroxide. Integration of ΦSa3 in LA-MRSA CC398 occurs at multiple positions and the integration site influences the stability of the prophage. We did not observe integration in hlb encoding β-hemolysin that contains the preferred ΦSa3 attachment site in human strains, and we demonstrate that this is due to allelic variation in CC398 strains that disrupts the phage attachment site, but not the expression of β-hemolysin. Our results show that hydrogen peroxide present in biocidal products stimulate transfer of ΦSa3 from human to LA-MRSA CC398 strains and that in these strains prophage stability depends on the integration site. Knowledge of ΦSa3 transfer and stability between human and livestock strains may lead to new intervention measures directed at reducing human infection by LA-MRSA strains.

  8. Commercial Biocides Induce Transfer of Prophage Φ13 from Human Strains of Staphylococcus aureus to Livestock CC398.

    Science.gov (United States)

    Tang, Yuanyue; Nielsen, Lene N; Hvitved, Annemette; Haaber, Jakob K; Wirtz, Christiane; Andersen, Paal S; Larsen, Jesper; Wolz, Christiane; Ingmer, Hanne

    2017-01-01

    Human strains of Staphylococcus aureus commonly carry the bacteriophage ΦSa3 that encodes immune evasion factors. Recently, this prophage has been found in livestock-associated, methicillin resistant S. aureus (MRSA) CC398 strains where it may promote human colonization. Here, we have addressed if exposure to biocidal products induces phage transfer, and find that during co-culture, Φ13 from strain 8325, belonging to ΦSa3 group, is induced and transferred from a human strain to LA-MRSA CC398 when exposed to sub-lethal concentrations of commercial biocides containing hydrogen peroxide. Integration of ΦSa3 in LA-MRSA CC398 occurs at multiple positions and the integration site influences the stability of the prophage. We did not observe integration in hlb encoding β-hemolysin that contains the preferred ΦSa3 attachment site in human strains, and we demonstrate that this is due to allelic variation in CC398 strains that disrupts the phage attachment site, but not the expression of β-hemolysin. Our results show that hydrogen peroxide present in biocidal products stimulate transfer of ΦSa3 from human to LA-MRSA CC398 strains and that in these strains prophage stability depends on the integration site. Knowledge of ΦSa3 transfer and stability between human and livestock strains may lead to new intervention measures directed at reducing human infection by LA-MRSA strains.

  9. Strain Induced Magnetism in SrRuO3 Epitaxial Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Grutter, A.; Wong, F.; Arenholz, E.; Liberati, M.; Suzuki, Y.

    2010-01-10

    Epitaxial SrRuO{sub 3} thin films were grown on SrTiO{sub 3}, (LaAlO{sub 3}){sub 0.3}(SrAlO{sub 3}){sub 0.7} and LaAlO{sub 3} substrates inducing different biaxial compressive strains. Coherently strained SrRuO{sub 3} films exhibit enhanced magnetization compared to previously reported bulk and thin film values of 1.1-1.6 {micro}{sub B} per formula unit. A comparison of (001) and (110) SrRuO{sub 3} films on each substrate indicates that films on (110) oriented have consistently higher saturated moments than corresponding (001) films. These observations indicate the importance of lattice distortions in controlling the magnetic ground state in this transitional metal oxide.

  10. Constitutive modelling of stainless steels for cryogenic applications. Strain induced martensitic transformation

    CERN Document Server

    Garion, C

    2001-01-01

    The 300-series stainless steels are metastable austenitic alloys: martensitic transformation occurs at low temperatures and/or when plastic strain fields develop in the structures. The transformation influences the mechanical properties of the material. The present note aims at proposing a set of constitutive equations describing the plastic strain induced martensitic transformation in the stainless steels at cryogenic temperatures. The constitutive modelling shall create a bridge between the material sciences and the structural analysis. For the structures developing and accumulating plastic deformations at sub-zero temperatures, it is of primary importance to be able to predict the intensity of martensitic transformation and its effect on the material properties. In particular, the constitutive model has been applied to predict the behaviour of the components of the LHC interconnections, the so-called bellows expansion joints (the LHC mechanical compensation system).

  11. Strain induced room temperature ferromagnetism in epitaxial magnesium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Zhenghe; Kim, Ki Wook [Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Nori, Sudhakar; Lee, Yi-Fang; Narayan, Jagdish [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Kumar, D. [Department of Mechanical Engineering, North Carolina A & T State University, Greensboro, North Carolina 27411 (United States); Wu, Fan [Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, New Jersey 08540 (United States); Prater, J. T. [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States)

    2015-10-28

    We report on the epitaxial growth and room-temperature ferromagnetic properties of MgO thin films deposited on hexagonal c-sapphire substrates by pulsed laser deposition. The epitaxial nature of the films has been confirmed by both θ-2θ and φ-scans of X-ray diffraction pattern. Even though bulk MgO is a nonmagnetic insulator, we have found that the MgO films exhibit ferromagnetism and hysteresis loops yielding a maximum saturation magnetization up to 17 emu/cc and large coercivity, H{sub c} = 1200 Oe. We have also found that the saturation magnetization gets enhanced and that the crystallization degraded with decreased growth temperature, suggesting that the origin of our magnetic coupling could be point defects manifested by the strain in the films. X-ray (θ-2θ) diffraction peak shift and strain analysis clearly support the presence of strain in films resulting from the presence of point defects. Based on careful investigations using secondary ion mass spectrometer and X-ray photoelectron spectroscopy studies, we have ruled out the possibility of the presence of any external magnetic impurities. We discuss the critical role of microstructural characteristics and associated strain on the physical properties of the MgO films and establish a correlation between defects and magnetic properties.

  12. Circular High-Q Resonating Isotropic Strain Sensors with Large Shift of Resonance Frequency under Stress

    Directory of Open Access Journals (Sweden)

    Hilmi Volkan Demir

    2009-11-01

    Full Text Available We present circular architecture bioimplant strain sensors that facilitate a strong resonance frequency shift with mechanical deformation. The clinical application area of these sensors is for in vivo assessment of bone fractures. Using a rectangular geometry, we obtain a resonance shift of 330 MHz for a single device and 170 MHz for its triplet configuration (with three side-by-side resonators on chip under an applied load of 3,920 N. Using the same device parameters with a circular isotropic architecture, we achieve a resonance frequency shift of 500 MHz for the single device and 260 MHz for its triplet configuration, demonstrating substantially increased sensitivity.

  13. Molecular Detection of Inducible Clindamycin Resistance among Staphylococcal Strains Isolated from Hospital Patients

    Directory of Open Access Journals (Sweden)

    Shadiyeh Abdollahi

    2013-04-01

    Full Text Available Background & Objectives: Macrolide, lincosamide and streptogramin B (MLSB antimicrobial agents are used in the treatment of staphylococcal infections. They prevent the microbial protein synthesis system through binding to 23 S rRNA. The aim of this study was to apply molecular methods to detect inducible clindamycin resistance genes among staphylococcal strains isolated from clinical specimens.   Methods : Two hundred staphylococcus strains were isolated from nose and throat swabs of patients in Toohid and Besat hospitals in Sanandaj . Antimicrobial susceptibilities of isolates were determined using disc diffusion method, agar screen test and D-Test. A multiplex PCR was performed using primers specific for erm (A, B, C, TR genes.   Results: Out of 200 isolates, 18.5 % were MRSA and 32% were MRCNS (methicillin resistant coagulase negative staphylococci. Of 80 erythromycin resistant isolates, 48 were coagulase negative and 32 were S. aureus. Among the 48 coagulase negative staphylococci (CONS isolates, 11.63% expressed the MLSB-inducible phenotypes. Using PCR, the frequency of different genes in the collection of isolates were as follows: ermA 5.41 % , erm B 5.41 % , and erm C 3.13%. The ermTR gene was negative in all isolates. Among the 32 S. aureus isolates, 9.38% expressed the MLSB-nducible phenotype. Using PCR, these isolates harbored erm A (2.22%, ermB (2.22%, ermC (2.22% and ermTR (2.22% .   Conclusion: This is the first study to show the rate of inducible clindamycin clinical isolates of staphylococci harboring erm genes in Sananadaj. It also demonstrated the frequency of erm genes was higher among CONS isolates than S. aureus. This data suggested the transfer of resistance gene from nonpathogenic to pathogenic strains is likely to happen. Therefore, screening and control of these resistance genes is recommended at clinical laboratories.

  14. New therapeutic approaches for management of sport-induced muscle strains.

    Science.gov (United States)

    De Carli, Angelo; Volpi, Piero; Pelosini, Iva; Ferretti, Andrea; Melegati, Gianluca; Mossa, Luigi; Tornese, Davide; de Girolamo, Laura; Scarpignato, Carmelo

    2009-12-01

    Muscle strains are one of the most common sports-induced injuries. Depending on the severity and location of the muscle strain, different treatment approaches can be taken. This review highlights recent trends in conservative, pharmacologic, and surgical approaches to the management of sports-induced muscle injuries as presented at a symposium held during the 93rd Annual Congress of the Italian Society of Orthopedics and Traumatology (SIOT) in Rome, Italy in November 2008. Conservative approaches now include growth factor therapy and administration of autologous platelet-rich plasma during the early postinjury period; however, its use is currently considered a doping violation under the World Anti-Doping Agency code, therefore restricting its use to nonelite sports people only. Topical anti-inflammatory therapy is a promising therapeutic strategy, since it allows local analgesic and anti-inflammatory effects while minimizing systemic adverse events. As the drug delivery system is critical to clinical effectiveness, the advent of a new delivery system for ketoprofen via a new-generation plaster with a marked increase in tissue penetration and a clinical efficacy comparable with that of oral administration, provides a viable option in the treatment of single sport lesions. Surgical treatment of muscle lesions is less common than conservative and topical therapies and indications are limited to more serious injuries. Presentations from SIOT 2008 show that advances in our understanding of the healing process and in conservative, pharmacologic, and surgical treatment approaches to the management of sports-induced muscle strains contribute to better clinical outcomes, faster healing, and a swifter return to normal training and activity levels.

  15. Differential infection properties of three inducible prophages from an epidemic strain of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    James Chloe E

    2012-09-01

    Full Text Available Abstract Background Pseudomonas aeruginosa is the most common bacterial pathogen infecting the lungs of patients with cystic fibrosis (CF. The Liverpool Epidemic Strain (LES is transmissible, capable of superseding other P. aeruginosa populations and is associated with increased morbidity. Previously, multiple inducible prophages have been found to coexist in the LES chromosome and to constitute a major component of the accessory genome not found in other sequenced P. aerugionosa strains. LES phages confer a competitive advantage in a rat model of chronic lung infection and may, therefore underpin LES prevalence. Here the infective properties of three LES phages were characterised. Results This study focuses on three of the five active prophages (LESφ2, LESφ3 and LESφ4 that are members of the Siphoviridae. All were induced from LESB58 by norfloxacin. Lytic production of LESφ2 was considerably higher than that of LESφ3 and LESφ4. Each phage was capable of both lytic and lysogenic infection of the susceptible P. aeruginosa host, PAO1, producing phage-specific plaque morphologies. In the PAO1 host background, the LESφ2 prophage conferred immunity against LESφ3 infection and reduced susceptibility to LESφ4 infection. Each prophage was less stable in the PAO1 chromosome with substantially higher rates of spontaneous phage production than when residing in the native LESB58 host. We show that LES phages are capable of horizontal gene transfer by infecting P. aeruginosa strains from different sources and that type IV pili are required for infection by all three phages. Conclusions Multiple inducible prophages with diverse infection properties have been maintained in the LES genome. Our data suggest that LESφ2 is more sensitive to induction into the lytic cycle or has a more efficient replicative cycle than the other LES phages.

  16. Spontaneous and mutagen-induced deletions: mechanistic studies in Salmonella tester strain TA102

    International Nuclear Information System (INIS)

    Levin, D.E.; Marnett, L.J.; Ames, B.N.

    1984-01-01

    Salmonella tester strain TA102 carries the hisG428 ochre mutation on the multicopy plasmid pAQ1. DNA sequence analysis of 45 spontaneous revertants of hisG428 on the chromosome in the presence of pKM101 (strain TA103) indicates that hisG428 revertants fall into three major categories: (i) small, in-frame deletions (3 or 6 base pairs) that remove part or all of the ochre triplet; (ii) base substitution mutations at the ochre site; (iii) extragenic ochre suppressors. Deletion revertants are identified in a simple phenotypic screen by their resistance to the inhibitory histidine analog thiazolealanine, which feedback inhibits the wild-type hisG enzyme but not the enzyme resulting from the deletions. The effect of various genetic backgrounds on the generation of spontaneous deletion revertants was examined. The presence of a uvrB mutation or a recA mutation suppressed the generation of spontaneous deletion revertants to approximately 1/2.5. When hisG428 was in multiple copies on pAQ1, the frequency of spontaneous deletion revertants increased by 40-fold, which is the approximate copy number of pAQ1. Mutagenic agents that induce single-strand breaks in DNA (e.g., x-rays, bleomycin, and nalidixic acid) induced deletion revertants in TA102. These agents induced deletion revertants only in hisG428 on pAQ1 and only in the presence of pKM101. Deletion revertants were not induced by frameshift mutagens (i.e., ICR-191 and 9aminoacridine). These results indicate that different pathways exist for the generation of spontaneous and mutagen-induced deletion revertants of hisG428. 41 references, 2 figures, 3 tables

  17. Identification of an Actual Strain-Induced Effect on Fast Ion Conduction in a Thin-Film Electrolyte.

    Science.gov (United States)

    Ahn, Junsung; Jang, Ho Won; Ji, Hoil; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon; Lee, Jong-Ho

    2018-05-09

    Strain-induced fast ion conduction has been a research area of interest for nanoscale energy conversion and storage systems. However, because of significant discrepancies in the interpretation of strain effects, there remains a lack of understanding of how fast ionic transport can be achieved by strain effects and how strain can be controlled in a nanoscale system. In this study, we investigated strain effects on the ionic conductivity of Gd 0.2 Ce 0.8 O 1.9-δ (100) thin films under well controlled experimental conditions, in which errors due to the external environment could not intervene during the conductivity measurement. In order to avoid any interference from perpendicular-to-surface defects, such as grain boundaries, the ionic conductivity was measured in the out-of-plane direction by electrochemical impedance spectroscopy analysis. With varying film thickness, we found that a thicker film has a lower activation energy of ionic conduction. In addition, careful strain analysis using both reciprocal space mapping and strain mapping in transmission electron microscopy shows that a thicker film has a higher tensile strain than a thinner film. Furthermore, the tensile strain of thicker film was mostly developed near a grain boundary, which indicates that intrinsic strain is dominant rather than epitaxial or thermal strain during thin-film deposition and growth via the Volmer-Weber (island) growth mode.

  18. Strain-assisted current-induced magnetization reversal in magnetic tunnel junctions: A micromagnetic study with phase-field microelasticity

    International Nuclear Information System (INIS)

    Huang, H. B.; Hu, J. M.; Yang, T. N.; Chen, L. Q.; Ma, X. Q.

    2014-01-01

    Effect of substrate misfit strain on current-induced in-plane magnetization reversal in CoFeB-MgO based magnetic tunnel junctions is investigated by combining micromagnetic simulations with phase-field microelasticity theory. It is found that the critical current density for in-plane magnetization reversal decreases dramatically with an increasing substrate strain, since the effective elastic field can drag the magnetization to one of the four in-plane diagonal directions. A potential strain-assisted multilevel bit spin transfer magnetization switching device using substrate misfit strain is also proposed.

  19. Inhomogeneous strain induced by fast neutron irradiation in NaKSO4 crystals

    International Nuclear Information System (INIS)

    Kandil, S.H.; El Gamal, M.A.; El Khatib, A.; El Wahidy, E.F.

    1987-06-01

    The effect of fast neutron irradiation on the thermal properties of NaKSO 4 crystals was studied around the phase transition temperature T c =453 K. The thermal expansion coefficient as well as the phase transition temperature were found to be dependent upon the irradiation dose. The specific heat, C p , showed multiple peaks in the phase transition temperature region. An explanation of this behaviour was based on the induced inhomogeneous strain in the crystal casued by the neutron irradiation process. (author). 10 refs, 3 figs

  20. Cyclic mechanical strain-induced proliferation and migration of human airway smooth muscle cells: role of EMMPRIN and MMPs.

    Science.gov (United States)

    Hasaneen, Nadia A; Zucker, Stanley; Cao, Jian; Chiarelli, Christian; Panettieri, Reynold A; Foda, Hussein D

    2005-09-01

    Airway smooth muscle (ASM) proliferation and migration are major components of airway remodeling in asthma. Asthmatic airways are exposed to mechanical strain, which contributes to their remodeling. Matrix metalloproteinase (MMP) plays an important role in remodeling. In the present study, we examined if the mechanical strain of human ASM (HASM) cells contributes to their proliferation and migration and the role of MMPs in this process. HASM were exposed to mechanical strain using the FlexCell system. HASM cell proliferation, migration and MMP release, activation, and expression were assessed. Our results show that cyclic strain increased the proliferation and migration of HASM; cyclic strain increased release and activation of MMP-1, -2, and -3 and membrane type 1-MMP; MMP release was preceded by an increase in extracellular MMP inducer; Prinomastat [a MMP inhibitor (MMPI)] significantly decreased cyclic strain-induced proliferation and migration of HASM; and the strain-induced increase in the release of MMPs was accompanied by an increase in tenascin-C release. In conclusion, cyclic mechanical strain plays an important role in HASM cell proliferation and migration. This increase in proliferation and migration is through an increase in MMP release and activation. Pharmacological MMPIs should be considered in the pursuit of therapeutic options for airway remodeling in asthma.

  1. Probing the Evolution of Retained Austenite in TRIP Steel During Strain-Induced Transformation: A Multitechnique Investigation

    Science.gov (United States)

    Haidemenopoulos, G. N.; Constantinou, M.; Kamoutsi, H.; Krizan, D.; Bellas, I.; Koutsokeras, L.; Constantinides, G.

    2018-06-01

    X-ray diffraction analysis, magnetic force microscopy, and the saturation magnetization method have been employed to study the evolution of the percentage and size of retained austenite (RA) particles during strain-induced transformation in a transformation-induced plasticity (TRIP) steel. A low-alloy TRIP-700 steel with nominal composition Fe-0.2C-0.34Si-1.99Mn-1Al (mass%) was subjected to interrupted tensile testing at strain levels of 0-22% and the microstructure subsequently studied. The results of the three experimental techniques were in very good agreement regarding the estimated austenite volume fraction and its evolution with strain. Furthermore, this multitechnique approach revealed that the average particle size of RA reduced as the applied strain was increased, suggesting that larger particles are less stable and more susceptible to strain-induced phase transformation. Such experimentally determined evolution of the austenite size with strain could serve as an input to kinetic models that aim to predict the strain-induced transformation in low-alloy TRIP steels.

  2. Time-scale invariant changes in atmospheric radon concentration and crustal strain prior to a large earthquake

    Directory of Open Access Journals (Sweden)

    Y. Kawada

    2007-01-01

    Full Text Available Prior to large earthquakes (e.g. 1995 Kobe earthquake, Japan, an increase in the atmospheric radon concentration is observed, and this increase in the rate follows a power-law of the time-to-earthquake (time-to-failure. This phenomenon corresponds to the increase in the radon migration in crust and the exhalation into atmosphere. An irreversible thermodynamic model including time-scale invariance clarifies that the increases in the pressure of the advecting radon and permeability (hydraulic conductivity in the crustal rocks are caused by the temporal changes in the power-law of the crustal strain (or cumulative Benioff strain, which is associated with damage evolution such as microcracking or changing porosity. As the result, the radon flux and the atmospheric radon concentration can show a temporal power-law increase. The concentration of atmospheric radon can be used as a proxy for the seismic precursory processes associated with crustal dynamics.

  3. Establishment of a tamoxifen-inducible Cre-driver mouse strain for widespread and temporal genetic modification in adult mice.

    Science.gov (United States)

    Ichise, Hirotake; Hori, Akiko; Shiozawa, Seiji; Kondo, Saki; Kanegae, Yumi; Saito, Izumu; Ichise, Taeko; Yoshida, Nobuaki

    2016-07-29

    Temporal genetic modification of mice using the ligand-inducible Cre/loxP system is an important technique that allows the bypass of embryonic lethal phenotypes and access to adult phenotypes. In this study, we generated a tamoxifen-inducible Cre-driver mouse strain for the purpose of widespread and temporal Cre recombination. The new line, named CM32, expresses the GFPneo-fusion gene in a wide variety of tissues before FLP recombination and tamoxifen-inducible Cre after FLP recombination. Using FLP-recombined CM32 mice (CM32Δ mice) and Cre reporter mouse lines, we evaluated the efficiency of Cre recombination with and without tamoxifen administration to adult mice, and found tamoxifen-dependent induction of Cre recombination in a variety of adult tissues. In addition, we demonstrated that conditional activation of an oncogene could be achieved in adults using CM32Δ mice. CM32Δ;T26 mice, which harbored a Cre recombination-driven, SV40 large T antigen-expressing transgene, were viable and fertile. No overt phenotype was found in the mice up to 3 months after birth. Although they displayed pineoblastomas (pinealoblastomas) and/or thymic enlargement due to background Cre recombination by 6 months after birth, they developed epidermal hyperplasia when administered tamoxifen. Collectively, our results suggest that the CM32Δ transgenic mouse line can be applied to the assessment of adult phenotypes in mice with loxP-flanked transgenes.

  4. A study of the relationship between saturated zone response and longwall mining-induced ground strain

    International Nuclear Information System (INIS)

    Trevits, M.A.; Matetic, R.J.

    1992-01-01

    The effects of longwall mining operations on near-surface water are not well understood. The sparse information that is available indicates a correlation between the proximity of the approaching longwall face and fluctuations in observation water wells. Furthermore, the magnitude of mining-induced subsidence appears to coincide with the degree of water level fluctuation. To provide additional information about these effects, the US Bureau of Mines has been installing well arrays over select longwall operations and observing the change as mining progresses through the area. Studies have been conducted at mine sites located in Pennsylvania and Ohio. The results of the research suggest that a relationship exists between water level fluctuations and the ground strain developed by the approaching longwall face. This paper explores research conducted at three mine sites and explains both the magnitude and timing of the observed water level fluctuations as a function of longwall mining-induced ground movement

  5. Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors

    Directory of Open Access Journals (Sweden)

    C. Gadermaier

    2014-03-01

    Full Text Available We use femtosecond optical spectroscopy to systematically measure the primary energy relaxation rate Γ_{1} of photoexcited carriers in cuprate and pnictide superconductors. We find that Γ_{1} increases monotonically with increased negative strain in the crystallographic a axis. Generally, the Bardeen-Shockley deformation potential theorem and, specifically, pressure-induced Raman shifts reported in the literature suggest that increased negative strain enhances electron-phonon coupling, which implies that the observed direct correspondence between a and Γ_{1} is consistent with the canonical assignment of Γ_{1} to the electron-phonon interaction. The well-known nonmonotonic dependence of the superconducting critical temperature T_{c} on the a-axis strain is also reflected in a systematic dependence T_{c} on Γ_{1}, with a distinct maximum at intermediate values (∼16  ps^{−1} at room temperature. The empirical nonmonotonic systematic variation of T_{c} with the strength of the electron-phonon interaction provides us with unique insight into the role of electron-phonon interaction in relation to the mechanism of high-T_{c} superconductivity as a crossover phenomenon.

  6. Rapid estimation of the moment magnitude of large earthquake from static strain changes

    Science.gov (United States)

    Itaba, S.

    2014-12-01

    The 2011 off the Pacific coast of Tohoku earthquake, of moment magnitude (Mw) 9.0, occurred on March 11, 2011. Based on the seismic wave, the prompt report of the magnitude which the Japan Meteorological Agency announced just after earthquake occurrence was 7.9, and it was considerably smaller than an actual value. On the other hand, using nine borehole strainmeters of Geological Survey of Japan, AIST, we estimated a fault model with Mw 8.7 for the earthquake on the boundary between the Pacific and North American plates. This model can be estimated about seven minutes after the origin time, and five minute after wave arrival. In order to grasp the magnitude of a great earthquake earlier, several methods are now being suggested to reduce the earthquake disasters including tsunami (e.g., Ohta et al., 2012). Our simple method of using strain steps is one of the strong methods for rapid estimation of the magnitude of great earthquakes.

  7. Use of endochronic plasticity for multi-dimensional small and large strain problems

    International Nuclear Information System (INIS)

    Hsieh, B.J.

    1980-04-01

    The endochronic plasticity theory was proposed in its general form by K.C. Valanis. An intrinsic time measure, which is a property of the material, is used in the theory. the explicit forms of the constitutive equation resemble closely those of the classical theory of linear viscoelasticity. Excellent agreement between the predicted and experimental results is obtained for some metallic and non-metallic materials for one dimensional cases. No reference on the use of endochronic plasticity consistent with the general theory proposed by Valanis is available in the open literature. In this report, the explicit constitutive equations are derived that are consistent with the general theory for one-dimensional (simple tension or compression), two-dimensional plane strain or stress and three-dimensional axisymmetric problems

  8. Large-Strain Monitoring Above a Longwall Coal Mine With GPS and Seismic Measurements

    Science.gov (United States)

    Swanson, P. L.; Andreatta, V.; Meertens, C. M.; Krahenbuhl, T.; Kenner, B.

    2001-12-01

    As part of an effort to evaluate continuous GPS measurements for use in mine safety studies, a joint GPS-seismic experiment was conducted at an underground longwall coal mine near Paonia, Colorado in June, 2001. Seismic and deformation signals were measured using prototype low-cost monitoring systems as a longwall panel was excavated 150 m beneath the site. Data from both seismic and GPS instruments were logged onto low-power PC-104 Linux computers which were networked using a wireless LAN. The seismic system under development at NIOSH/SRL is based on multiple distributed 8-channel 24-bit A/D converters. The GPS system uses a serial single-frequency (L1) receiver and UNAVCO's "Jstream" Java data logging software. For this experiment, a continuously operating dual-frequency GPS receiver was installed 2.4 km away to serve as a reference site. In addition to the continuously operating sites, 10 benchmarks were surveyed daily with short "rapid-static" occupations in order to provide greater spatial sampling. Two single-frequency sites were located 35 meters apart on a relatively steep north-facing slope. As mining progressed from the east, net displacements of 1.2 meters to the north and 1.65 meters of subsidence were observed over a period of 6 days. The east component exhibited up to 0.45 meters of eastward displacement (toward the excavation) followed by reverse movement to the west. This cycle, observed approximately two days earlier at the eastern L1 site, is consistent with a change in surface strain from tension to compression as the excavation front passed underneath. As this strain "wave" propagated across the field site, surface deformation underwent a cycle of tension crack nucleation, crack opening (up to 15 cm normal displacements), subsequent crack closure, and production of low-angle-thrust compressional deformation features. Analysis of seismic results, surface deformation, and additional survey results are presented.

  9. Strain-induced alignment and phase behavior of blue phase liquid crystals confined to thin films.

    Science.gov (United States)

    Bukusoglu, Emre; Martinez-Gonzalez, Jose A; Wang, Xiaoguang; Zhou, Ye; de Pablo, Juan J; Abbott, Nicholas L

    2017-12-06

    We report on the influence of surface confinement on the phase behavior and strain-induced alignment of thin films of blue phase liquid crystals (BPs). Confining surfaces comprised of bare glass, dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride (DMOAP)-functionalized glass, or polyvinyl alcohol (PVA)-coated glass were used with or without mechanically rubbing to influence the azimuthal anchoring of the BPs. These experiments reveal that confinement can change the phase behavior of the BP films. For example, in experiments performed with rubbed-PVA surfaces, we measured the elastic strain of the BPs to change the isotropic-BPII phase boundary, suppressing formation of BPII for film thicknesses incommensurate with the BPII lattice. In addition, we observed strain-induced alignment of the BPs to exhibit a complex dependence on both the surface chemistry and azimuthal alignment of the BPs. For example, when using bare glass surfaces causing azimuthally degenerate and planar anchoring, BPI oriented with (110) planes of the unit cell parallel to the contacting surfaces for thicknesses below 3 μm but transitioned to an orientation with (200) planes aligned parallel to the contacting surfaces for thicknesses above 4 μm. In contrast, BPI aligned with (110) planes parallel to confining surfaces for all other thicknesses and surface treatments, including bare glass with uniform azimuthal alignment. Complementary simulations based on minimization of the total free energy (Landau-de Gennes formalism) confirmed a thickness-dependent reorientation due to strain of BPI unit cells within a window of surface anchoring energies and in the absence of uniform azimuthal alignment. In contrast to BPI, BPII did not exhibit thickness-dependent orientations but did exhibit orientations that were dependent on the surface chemistry, a result that was also captured in simulations by varying the anchoring energies. Overall, the results in this paper reveal that the orientations

  10. Slow Light Using Electromagnetically Induced Transparency from Spin Coherence in [110] Strained Quantum Wells

    Science.gov (United States)

    Chang, Shu-Wei; Chang-Hasnain, Connie J.; Wang, Hailin

    2005-03-01

    The electromagnetically induced transparency from spin coherence has been proposed in [001] quantum wells recently. [1] The spin coherence is a potential candidate to demonstrate semiconductor-based slow light at room temperature. However, the spin coherence time is not long enough to demonstrate a significant slowdown factor in [001] quantum wells. Further, the required transition of light-hole excitons lies in the absorption of heavy-hole continuum states. The extra dephasing and absorption from these continuum states are drawbacks for slow light. Here, we propose to use [110] strained quantum wells instead of [001] quantum wells. The long spin relaxation time in [110] quantum wells at room temperature, and thus more robust spin coherence, [2] as well as the strain-induced separation [3, 4] of the light-hole exciton transition from the heavy-hole continuum absorption can help to slow down light in quantum wells. [1] T. Li, H. Wang, N. H. Kwong, and R. Binder, Opt. Express 11, 3298 (2003). [2] Y. Ohno, R. Terauchi, T. Adachi, F. Matsukura, and H. Ohno, Phys. Rev. Lett. 83, 4196 (1999). [3] C. Y. P. Chao and S. L. Chuang, Phys. Rev. B 46, 4110 (1992). [4] C. Jagannath, E. S. Koteles, J. Lee, Y. J. Chen, B. S. Elman, and J. Y. Chi, Phys. Rev. B 34, 7027 (1986).

  11. Penicillin G-Induced Chlamydial Stress Response in a Porcine Strain of Chlamydia pecorum

    Directory of Open Access Journals (Sweden)

    Cory Ann Leonard

    2016-01-01

    Full Text Available Chlamydia pecorum causes asymptomatic infection and pathology in ruminants, pigs, and koalas. We characterized the antichlamydial effect of the beta lactam penicillin G on Chlamydia pecorum strain 1710S (porcine abortion isolate. Penicillin-exposed and mock-exposed infected host cells showed equivalent inclusions numbers. Penicillin-exposed inclusions contained aberrant bacterial forms and exhibited reduced infectivity, while mock-exposed inclusions contained normal bacterial forms and exhibited robust infectivity. Infectious bacteria production increased upon discontinuation of penicillin exposure, compared to continued exposure. Chlamydia-induced cell death occurred in mock-exposed controls; cell survival was improved in penicillin-exposed infected groups. Similar results were obtained both in the presence and in the absence of the eukaryotic protein translation inhibitor cycloheximide and at different times of initiation of penicillin exposure. These data demonstrate that penicillin G induces the chlamydial stress response (persistence and is not bactericidal, for this chlamydial species/strain in vitro, regardless of host cell de novo protein synthesis.

  12. Finite-strain micromechanical model of stress-induced martensitic transformations in shape memory alloys

    International Nuclear Information System (INIS)

    Stupkiewicz, S.; Petryk, H.

    2006-01-01

    A micromechanical model of stress-induced martensitic transformation in single crystals of shape memory alloys is developed. This model is a finite-strain counterpart to the approach presented recently in the small-strain setting [S. Stupkiewicz, H. Petryk, J. Mech. Phys. Solids 50 (2002) 2303-2331]. The stress-induced transformation is assumed to proceed by the formation and growth of parallel martensite plates within the austenite matrix. Propagation of phase transformation fronts is governed by a rate-independent thermodynamic criterion with a threshold value for the thermodynamic driving force, including in this way the intrinsic dissipation due to phase transition. This criterion selects the initial microstructure at the onset of transformation and governs the evolution of the laminated microstructure at the macroscopic level. A multiplicative decomposition of the deformation gradient into elastic and transformation parts is assumed, with full account for the elastic anisotropy of the phases. The pseudoelastic behavior of Cu-Zn-Al single crystal in tension and compression is studied as an application of the model

  13. Large scale vibration tests on pile-group effects using blast-induced ground motion

    International Nuclear Information System (INIS)

    Katsuichirou Hijikata; Hideo Tanaka; Takayuki Hashimoto; Kazushige Fujiwara; Yuji Miyamoto; Osamu Kontani

    2005-01-01

    Extensive vibration tests have been performed on pile-supported structures at a large-scale mining site. Ground motions induced by large-scale blasting operations were used as excitation forces for vibration tests. The main objective of this research is to investigate the dynamic behavior of pile-supported structures, in particular, pile-group effects. Two test structures were constructed in an excavated 4 m deep pit. Their test-structures were exactly the same. One structure had 25 steel piles and the other had 4 piles. The test pit was backfilled with sand of appropriate grain size distributions to obtain good compaction, especially between the 25 piles. Accelerations were measured at the structures, in the test pit and in the adjacent free field, and pile strains were measured. Dynamic modal tests of the pile-supported structures and PS measurements of the test pit were performed before and after the vibration tests to detect changes in the natural frequencies of the soil-pile-structure systems and the soil stiffness. The vibration tests were performed six times with different levels of input motions. The maximum horizontal acceleration recorded at the adjacent ground surface varied from 57 cm/s 2 to 1,683 cm/s 2 according to the distances between the test site and the blast areas. (authors)

  14. Coculture-inducible bacteriocin activity of Lactobacillus plantarum strain J23 isolated from grape must.

    Science.gov (United States)

    Rojo-Bezares, Beatriz; Sáenz, Yolanda; Navarro, Laura; Zarazaga, Myriam; Ruiz-Larrea, Fernanda; Torres, Carmen

    2007-08-01

    Detection and characterization of bacteriocin production by Lactobacillus plantarum strain J23, recovered from a grape must sample in Spain, have been carried out. Bacteriocin activity was degraded by proteolytic enzymes (trypsin, alfa-chymotrypsin, papaine, protease, proteinase K and acid proteases), and it was stable at high temperatures (121 degrees C, 20min), in a wide range of pH (1-12), and after treatment with organic solvents. L. plantarum J23 showed antimicrobial activity against Oenococcus oeni, and a range of Lactobacillus and Pediococcus species. Bacteriocin production was detected in liquid media only when J23 was cocultivated with some inducing bacteria, and induction took place when intact cells or 55 degrees C heated cells of the inducer were cocultivated with J23, but not with their autoclaved cells. Bacteriocin activity of J23 was not induced by high initial J23 inocula, and it was detected in cocultures during the exponential phase. The presence of ethanol or acidic pH in the media reduced bacteriocin production in the cocultures of J23 with the inducing bacteria. The presence of plantaricin-related plnEF and plnJ genes was detected by PCR and sequencing. Nevertheless, negative results were obtained for plnA, plnK, plNC8, plS and plW genes.

  15. Characterization of an exo-chitinase from a Citrobacter strain isolated from the intestine content of large yellow croakers.

    Science.gov (United States)

    Xu, Jie; Yang, Yalin; Liu, Yang; Ran, Chao; Li, Juan; He, Suxu; Xu, Li; Ai, Xhunxiang; Zhou, Zhigang

    2016-07-04

    We isolated bacterial strains with chitin-degrading activity from the digesta of large yellow croakers (Pseudosciaena crocea) fed with chitin-enriched trash fish, and characterized potential chitinases thereof. Chitin-degrading strains were screened with colloidal chitin agar from the digesta of P. crocea fed with trash fish. The chitinase gene (chi-X) was cloned and expressed in Escherichia coli, and the enzymatic properties of the chitinase (CHI-X) were characterized. A Citrobacter freundii strain with chitin-degrading activity was isolated. The chitinase gene encodes a protein containing 493 amino acid residues, with a proposed glycoside hydrolase family-18 catalytic domain. CHI-X could hydrolyze colloidal chitin. The optimal pH for CHI-X was 4.0 at optimal temperature (60 ℃). CHI-X was active over a broad pH range, with around 90% of the activity maintained after incubation at pH between 3.0 and 11 for 1 h. The enzymatic activity of CHI-X was stimulated by Mn2+, Li+, and K+, but inhibited by Ag+. The enzyme was stable after treatment by proteases and grouper intestinal juice. CHI-X hydrolyzes colloidal chitin into GlcNAc and (GlcNAc)2. Furthermore, an synergic effect was observed between CHIX and ChiB565 (a chitinase from Aeromonas veronii B565) on colloidal chitin. CHI-X from intestinal bacterium may be potentially used as feed additive enzyme for warm water marine fish.

  16. Large diameter femoral heads impose significant alterations on the strains developed on femoral component and bone: a finite element analysis.

    Science.gov (United States)

    Theodorou, E G; Provatidis, C G; Babis, G C; Georgiou, C S; Megas, P D

    2011-01-01

    Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost's law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used.

  17. A Pseudomonas aeruginosa strain isolated from a contact lens-induced acute red eye (CLARE) is protease-deficient.

    Science.gov (United States)

    Estrellas, P S; Alionte, L G; Hobden, J A

    2000-03-01

    Pseudomonas aeruginosa proteases are thought to be important virulence factors in the pathogenesis of corneal disease. This study examined protease production from two strains of P. aeruginosa responsible for two very distinct clinical diseases: strain Paer1, isolated from a Contact Lens-induced Acute Red Eye (CLARE), and strain KEI 1025, isolated from a corneal ulcer. Strains were compared to a laboratory strain (ATCC 19660) known to produce severe keratitis in experimentally infected mice for protease production and for ocular virulence. Protease production was examined with colorimetric assays, gelatin zymography and western blots. Elastase A activity was quantitated with a staphylolytic assay. Ocular virulence was examined using a mouse scratch model of keratitis. In contrast to strains KEI 1025 or ATCC 19660, Paer1 was unable to produce enzymatically active elastase A, elastase, and protease IV. All three strains produced active alkaline protease. Strains KEI 1025 and ATCC 19660 produced a fulminant keratitis in mice whereas Paer1 produced a mild transient infection. Restoration of elastase activity in Paer1 via genetic complementation did not result in a virulent phenotype. Co-infection of mouse eyes with strains Paer1 and ATCC 19660 resulted in the eventual loss of Paer1 from corneal tissue. These studies suggest that P. aeruginosa elastase A and/or protease IV, but not alkaline protease or elastase, contribute to the ocular virulence of this organism.

  18. Spontaneous and UV-induced variations in the activity of biomass synthesis in Candida utilis haploid and diploid strains

    International Nuclear Information System (INIS)

    Kondrat'eva, T.F.; Lin'kova, M.A.; Lobacheva, N.A.

    1988-01-01

    Candida utilis diploid strains have greater variations induced by UV irradiation in the activity of biomass synthesis as compared with the parent haploid culture. Clones with an activity of the synthesis greater that the mean population one appear more frequently in the diploid strains. Mathematical analysis has confirmed the significance of the results and the hypothesis according to which the frequency of variants more active in biomass synthesis rises after the action of UV

  19. Hormone-induced protection against mammary tumorigenesis is conserved in multiple rat strains and identifies a core gene expression signature induced by pregnancy.

    Science.gov (United States)

    Blakely, Collin M; Stoddard, Alexander J; Belka, George K; Dugan, Katherine D; Notarfrancesco, Kathleen L; Moody, Susan E; D'Cruz, Celina M; Chodosh, Lewis A

    2006-06-15

    Women who have their first child early in life have a substantially lower lifetime risk of breast cancer. The mechanism for this is unknown. Similar to humans, rats exhibit parity-induced protection against mammary tumorigenesis. To explore the basis for this phenomenon, we identified persistent pregnancy-induced changes in mammary gene expression that are tightly associated with protection against tumorigenesis in multiple inbred rat strains. Four inbred rat strains that exhibit marked differences in their intrinsic susceptibilities to carcinogen-induced mammary tumorigenesis were each shown to display significant protection against methylnitrosourea-induced mammary tumorigenesis following treatment with pregnancy levels of estradiol and progesterone. Microarray expression profiling of parous and nulliparous mammary tissue from these four strains yielded a common 70-gene signature. Examination of the genes constituting this signature implicated alterations in transforming growth factor-beta signaling, the extracellular matrix, amphiregulin expression, and the growth hormone/insulin-like growth factor I axis in pregnancy-induced alterations in breast cancer risk. Notably, related molecular changes have been associated with decreased mammographic density, which itself is strongly associated with decreased breast cancer risk. Our findings show that hormone-induced protection against mammary tumorigenesis is widely conserved among divergent rat strains and define a gene expression signature that is tightly correlated with reduced mammary tumor susceptibility as a consequence of a normal developmental event. Given the conservation of this signature, these pathways may contribute to pregnancy-induced protection against breast cancer.

  20. Prediction of process induced shape distortions and residual stresses in large fibre reinforced composite laminates

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani

    to their accuracy in predicting process induced strain and stress development in thick section laminates during curing, and more precisely regarding the evolution of the composite thermoset polymer matrix mechanical behaviour during the phase transitions experienced during curing. The different constitutive...

  1. Analysis of the strain induced martensitic transformation in austenitic steel subjected to dynamic perforation

    Directory of Open Access Journals (Sweden)

    Zaera R.

    2012-08-01

    Full Text Available An experimental and numerical analysis on the martensitic transformation in AISI 304 steel sheets subjected to perforation by conical and hemispherical projectiles is reported. Two target thicknesses are considered, 0.5 and 1.0 mm, and impact velocities range from 35 to 200 m/s. The perforation mechanisms are identified and the effect of the projectile nose-shape on the ability of the target for energy absorption is evaluated. Martensite has been detected in all the impacted samples and the role played by the projectile nose-shape on the transformation is highlighted. A 3D model implemented in ABAQUS/Explicit allowed to simulate the perforation tests. The material is defined through a constitutive description developed by the authors to describe the strain induced martensitic transformation taking place in metastable austenitic steels at high strain rates. The numerical results are compared with the experimental evidence and satisfactory matching is obtained. The numerical model succeeds in describing the perforation mechanisms associated to each projectile-target configuration analysed.

  2. Tear energy and strain-induced crystallization of natural rubber/styrene-butadiene rubber blend

    International Nuclear Information System (INIS)

    Noguchi, F; Akabori, K; Yamamoto, Y; Kawahara, S; Kawazura, T

    2009-01-01

    Strain-induced crystallization of natural rubber (NR), dispersed in styrene-butadiene rubber (SBR), was investigated in relation to dimensional feature of a dispersoid and crosslink density of NR by measuring tear energy (G) of crosslinked NR/SBR blends. The crosslinked NR/SBR blends in ratios of 1/9 and 3/7 by weight were prepared by mixing masticated NR and SBR with an internal mixer at a rotor speed of 30 rpm, followed by crosslinking with dicumyl peroxide on a hot press at 444 K for 60 min. The G, measured in wide-ranges of temperature and tear rate, was superposed into a master curve with a Williams-Landel-Ferry shift factor. The G of the NR/SBR(3/7) blend abruptly decreased to a level comparable to that of SBR at about melting temperature of NR crystals formed on straining. The temperature, at which the dramatic decrease in the G occurred, was associated with the dimensional feature of the NR dispersoid and the crosslink density.

  3. Strain-Induced Martensitic Transformation and Texture Evolution in Cold-Rolled Co–Cr Alloys

    Directory of Open Access Journals (Sweden)

    Yusuke Onuki

    2018-05-01

    Full Text Available Co–Cr alloys have been used in biomedical purposes such as stents and artificial hip joints. However, the difficulty of plastic deformation limits the application of the alloys. During the deformation, Co–Cr alloys often exhibit strain-induced martensitic transformation (SIMT, which is a possible reason for the low formability. The distinct increase in dislocation density in the matrix phase may also result in early fractures. Since these microstructural evolutions accompany the textural evolution, it is crucial to understand the relationship among the SIMT, the increase in dislocations, and the texture evolution. To characterize those at the same time, we conducted time-of-flight neutron diffraction experiments at iMATERIA beamline at the Japan Proton Accelerator Research Complex (J-PARC Materials and Life Science Experimental Facility (MLF, Ibaraki, Japan. The cold-rolled sheets of Co–29Cr–6Mo (CCM and Co–20Cr–15W–10Ni (CCWN alloys were investigated in this study. As expected from the different stacking fault energies, the SIMT progressed more rapidly in the CCM alloy. The dislocation densities of the matrix phases of the CCM and CCWN alloys increased similarly with an increase in the rolling reduction. These results suggest that the difference in deformability between the CCM and CCWN alloys originate not from the strain hardening of the matrix phase but from the growth behaviors of the martensitic phase.

  4. Strain-induced corrosion cracking in ferritic components of BWR primary circuits

    International Nuclear Information System (INIS)

    Seifert, H.-P.; Ritter, S.; Ineichen, U.; Tschanz, U.; Gerodetti, B.

    2003-04-01

    The present final report of the RIKORR project is a summary of a literature survey and of the experimental work performed by PSI on the environmentally-assisted cracking (EAC) and dynamic strain ageing (DSA) susceptibility of low-alloy steels (LAS) in high-temperature (HT) water. Within this project, the EAC crack growth behaviour of different low-alloy RPV steels, weld filler and weld heat-affected zone materials has been investigated under simulated transient and steady-state BWR/NWC power operation conditions. The strain-induced corrosion cracking (SICC) / low-frequency corrosion fatigue (CF) and stress corrosion cracking (SCC) crack growth behaviour of different low-alloy RPV steels under simulated transient and stationary BWR/NWC conditions was characterized by slow rising load / low-frequency corrosion fatigue and constant load / periodical partial unloading / ripple load tests with pre-cracked fracture mechanics specimens in oxygenated HT water at temperatures of either 288, 250, 200 or 150 o C. Modern high-temperature water loops, on-line crack growth monitoring and fractographic analysis by scanning electron microscopy (SEM) were used to quantify the cracking response. (author)

  5. Morphology and formation mechanism in precipitation of calcite induced by Curvibacter lanceolatus strain HJ-1

    Science.gov (United States)

    Zhang, Chonghong; Li, Fuchun; Lv, Jiejie

    2017-11-01

    Precipitation of calcium carbobate induced by microbial activities is common occurrence in controlled solution, but the formation mechanism and morphology in precipitation of calcite in solution systems is unclear, and the role of microbes is disputed. Here, culture experiment was performed for 50 days using the Curvibacter lanceolatus strain HJ-1 in a M2 culture medium, and the phase composition and morphology of the precipitates were characterized by the X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) techniques. We show that the precipitation processes in our experiment lead to unusual morphologies of crystals corresponding to different growth stages, and the morphologies of the precipitated crystal aggregates ranging from the main rod-, cross-, star-, cauliflower-like morphologies to spherulitic structure. The complex and unusual morphologies of the precipitated calcite by strain HJ-1 may provide a reference point for better understanding the biomineralization mechanism of calcite, moreover, morphological transition of minerals revealed that the multi-ply crystals-aggregation mechanism for calcite growth in crystallisation media.

  6. Vortex-ring-induced large bubble entrainment during drop impact

    KAUST Repository

    Thoraval, Marie-Jean

    2016-03-29

    For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

  7. The influence of grain size on the strain-induced martensite formation in tensile straining of an austenitic 15Cr–9Mn–Ni–Cu stainless steel

    International Nuclear Information System (INIS)

    Kisko, A.; Misra, R.D.K.; Talonen, J.; Karjalainen, L.P.

    2013-01-01

    In order to improve understanding on the behavior of ultrafine-grained austenitic stainless steels during deformation, the influence of the austenite grain size and microstructure on the strain-induced martensite transformation was investigated in an austenitic 15Cr–9Mn–Ni–Cu (Type 204Cu) stainless steel. By different reversion treatments of the 60% cold-rolled sheet, varying grain sizes from ultrafine (0.5 μm), micron-scale (1.5 μm), fine (4 μm) to coarse (18 μm) were obtained. Some microstructures also contained a mixture of ultrafine or micron-scale and coarse initially cold-worked austenite grains. Samples were tested in tensile loading and deformation structures were analyzed after 2%, 10% and 20% engineering strains by means of martensite content measurements, scanning electron microscope together with a electron backscatter diffraction device and transmission electron microscope. The results showed that the martensite nucleation sites and the rate of transformation vary. In ultrafine grains strain-induced α′-martensite nucleates at grain boundaries and twins, whereas in coarser grains as well as in coarse-grained retained austenite, α′-martensite formation occurs at shear bands, sometimes via ε-martensite. The transformation rate of strain-induced α′-martensite decreases with decreasing grain size to 1.5 μm. However, the rate is fastest in the microstructure containing a mixture of ultrafine and retained cold-worked austenite grains. There the ultrafine grains transform quite readily to martensite similarly as the coarse retained austenite grains, where the previous cold-worked microstructure is still partly remaining

  8. Detecting hepatic steatosis using ultrasound-induced thermal strain imaging: an ex vivo animal study

    International Nuclear Information System (INIS)

    Mahmoud, Ahmed M; Ding, Xuan; Dutta, Debaditya; Kim, Kang; Singh, Vijay P

    2014-01-01

    Hepatic steatosis or fatty liver disease occurs when lipids accumulate within the liver and can lead to steatohepatitis, cirrhosis, liver cancer and eventual liver failure requiring liver transplant. Conventional brightness mode (B-mode) ultrasound (US) is the most common noninvasive diagnostic imaging modality used to diagnose hepatic steatosis in clinics. However, it is mostly subjective or requires a reference organ such as the kidney or spleen with which to compare. This comparison can be problematic when the reference organ is diseased or absent. The current work presents an alternative approach to noninvasively detecting liver fat content using US-induced thermal strain imaging (US-TSI). This technique is based on the difference in the change in the speed of sound as a function of temperature between water- and lipid-based tissues. US-TSI was conducted using two system configurations including a mid-frequency scanner with a single linear array transducer (5–14 MHz) for both imaging and heating and a high-frequency (13–24 MHz) small animal imaging system combined with a separate custom-designed US heating transducer array. Fatty livers (n = 10) with high fat content (45.6 ± 11.7%) from an obese mouse model and control livers (n = 10) with low fat content (4.8 ± 2.9%) from wild-type mice were embedded in gelatin. Then, US imaging was performed before and after US induced heating. Heating time periods of ∼3 s and ∼9.2 s were used for the mid-frequency imaging and high-frequency imaging systems, respectively, to induce temperature changes of approximately 1.5 °C. The apparent echo shifts that were induced as a result of sound speed change were estimated using 2D phase-sensitive speckle tracking. Following US-TSI, histology was performed to stain lipids and measure percentage fat in the mouse livers. Thermal strain measurements in fatty livers (−0.065 ± 0.079%) were significantly (p < 0.05) higher than those measured in control livers (−0.124

  9. Large-scale coastal impact induced by a catastrophic storm

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Andersen, Thorbjørn Joest; Johannessen, Peter N

    breaching. Our results demonstrate that violent, millennial-scale storms can trigger significant large-scale and long-term changes on barrier coasts, and that coastal changes assumed to take place over centuries or even millennia may occur in association with a single extreme storm event....

  10. Vortex-ring-induced large bubble entrainment during drop impact

    KAUST Repository

    Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T

    2016-01-01

    , produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self

  11. MD simulations to evaluate effects of applied tensile strain on irradiation-induced defect production at various PKA energies

    International Nuclear Information System (INIS)

    Miyashiro, S.; Fujita, S.; Okita, T.; Okuda, H.

    2012-01-01

    Highlights: ► Strain effects on defect formation were evaluated at various PKA energies by MD. ► Radiation-induced defects were increased numerically by external strain. ► Enhanced formation of larger clusters causes the numerical increase of defects. ► Strain influence on the number of defects was greatest at about 20 keV PKA. ► Cluster size, which is mostly affected by strain, was greater with higher PKA energy. - Abstract: Molecular Dynamics (MD) simulations were conducted to investigate the influence of applied tensile strain on defect production during cascade damages at various Primary Knock-on Atom (PKA) energies of 1–30 keV. When 1% strain was applied, the number of surviving defects increased at PKA energies higher than 5 keV, although they did not increase at 1 keV. The rate of increase by strain application was higher with higher PKA energy, and attained the maximum at 20 keV PKA energy with a subsequent gradual decrease at 30 keV PKA energy The cluster size, mostly affected by strain, was larger with higher PKA energy, although clusters with fewer than seven interstitials did not increase in number at any PKA energy.

  12. Acid resistance and response to pH-induced stress in two Lactobacillus plantarum strains with probiotic potential.

    Science.gov (United States)

    Šeme, H; Gjuračić, K; Kos, B; Fujs, Š; Štempelj, M; Petković, H; Šušković, J; Bogovič Matijašić, B; Kosec, G

    2015-01-01

    Two new Lactobacillus plantarum strains, KR6-DSM 28780 and M5 isolated from sour turnip and traditional dried fresh cheese, respectively, were evaluated for species identity, antibiotic susceptibility, resistance to gastrointestinal conditions and adaptive response to low pH. Resistance mechanisms involved in the adaptation to acid-induced stress in these two strains were investigated by quantitative PCR of the atpA, cfa1, mleS and hisD genes. In addition to absence of antibiotic resistance, the two L. plantarum strains showed excellent survival rates at pH values as low as 2.4. Adaptive response to low pH was clearly observed in both strains; strain KR6 was superior to M5, as demonstrated by its ability to survive during 3 h incubation at pH 2.0 upon adaptation to moderately acidic conditions. In contrast, acid adaptation did not significantly affect the survival rate during simulated passage through the gastrointestinal tract. In both strains, induction of histidine biosynthesis (hisD) was upregulated during the acid adaptation response. In addition, significant upregulation of the cfa1 gene, involved in modulation of membrane fatty acid composition, was observed during the adaptation phase in strain KR6 but not in strain M5. Cells adapted to moderately acidic conditions also showed a significantly increased viability after the lyophilisation procedure, a cross-protection phenomenon providing additional advantage in probiotic application.

  13. Self-consistent modelling of lattice strains during the in-situ tensile loading of twinning induced plasticity steel

    International Nuclear Information System (INIS)

    Saleh, Ahmed A.; Pereloma, Elena V.; Clausen, Bjørn; Brown, Donald W.; Tomé, Carlos N.; Gazder, Azdiar A.

    2014-01-01

    The evolution of lattice strains in a fully recrystallised Fe–24Mn–3Al–2Si–1Ni–0.06C TWinning Induced Plasticity (TWIP) steel subjected to uniaxial tensile loading up to a true strain of ∼35% was investigated via in-situ neutron diffraction. Typical of fcc elastic and plastic anisotropy, the {111} and {200} grain families record the lowest and highest lattice strains, respectively. Using modelling cases with and without latent hardening, the recently extended Elasto-Plastic Self-Consistent model successfully predicted the macroscopic stress–strain response, the evolution of lattice strains and the development of crystallographic texture. Compared to the isotropic hardening case, latent hardening did not have a significant effect on lattice strains and returned a relatively faster development of a stronger 〈111〉 and a weaker 〈100〉 double fibre parallel to the tensile axis. Close correspondence between the experimental lattice strains and those predicted using particular orientations embedded within a random aggregate was obtained. The result suggests that the exact orientations of the surrounding aggregate have a weak influence on the lattice strain evolution

  14. Electrically Induced Strain and Polarization Fatigue in Lead-Free Ceramics

    Science.gov (United States)

    Sommer, Daniel

    Piezoelectric ceramics have traditionally been used in commercial applications such as actuators and sensors. By far the most popular piezoceramics currently in use are Pb(Zr,Ti)O3-based (PZT) ceramics. PZT ceramics are able to produce large strain and polarization with the application of an electric field, and this is due to the Morphotropic phase boundary (MPB). A MPB is associated with the boundary between tetragonal and rhombohedral perovskite phases. A disadvantage of PZT ceramics is that they contain ? 60 wt. % of lead. Since lead is toxic, this poses an environmental and health hazard because lead is released into the surroundings during fabrication and disposal. Because of this, there is a push to discover lead-free alternatives that have comparable properties to PZT but none of the health risks. One possibility is Bi 1/2(Na0.8K0.2)1/2Ti0.985 Ta0.015O3 (BNKT-1.5Ta). In addition to comparable electrical properties, any lead-free alternatives must have decent fatigue resistance to be useful for applications. This thesis focuses on the fatigue properties of BNKT-1.5Ta. The composition demonstrates high strain for a given applied electric field. To determine the fatigue resistance of BNKT-1.5Ta, data was gathered on how strain and polarization changed over number of cycles. Furthermore, fatigue tests at different temperatures were performed to ascertain if temperature affected fatigue life. X-ray diffraction (XRD) patterns and dielectric measurements were also collected to further examine any change in crystal structure and relative permittivity, respectively, before and after cycling.

  15. Low-voltage, large-strain soft electrothermal actuators based on laser-reduced graphene oxide/Ag particle composites

    Science.gov (United States)

    Wang, Qian; Li, Yu-Tao; Zhang, Tian-Yu; Wang, Dan-Yang; Tian, Ye; Yan, Jun-Chao; Tian, He; Yang, Yi; Yang, Fan; Ren, Tian-Ling

    2018-03-01

    In this paper, low-voltage, large-strain flexible electrothermal actuators (ETAs) based on laser-reduced graphene oxide (LRGO)/Ag particle composites were fabricated in a simple and cost-efficient process. By adding Ag particles to the LRGO, the sheet resistance decreased effectively. Under a driving voltage of 28 V, the actuator obtained a bending angle of 192° within 6 s. Besides, the bending deformation could be precisely controlled by the driving voltage ranging from 10° to 192°. Finally, a gripper composed of two actuators was demonstrated to manipulate a piece of polydimethylsiloxane block. With the advantages of low-voltage, fast-response, and easy-to-manufacture, the graphene based ETAs have a promising application in soft robotics and soft machines.

  16. Strain differences in the somnogenic effects of interferon inducers in mice.

    Science.gov (United States)

    Toth, L A

    1996-12-01

    Increased slow-wave sleep accompanies influenza infection in C57BL/6 mice but not BALB/c mice. These strains of mice possess different alleles of the genetic lucus If-1, which codes for high (If-1h; C57BL/6) and low (If-1(1); BALB/c) production of interferon (IFN), a putative sleep-inducing cytokine. To evaluate the contribution of the If-1 gene to differences in murine sleep propensity, sleep patterns were evaluated in mice treated with the IFN inducers polyinosinic:polycytidilic acid (pIC) or Newcastle disease virus (NDV), with influenza virus, or with murine interferon (IFN-alpha) or IFN-alpha/beta. As compared with baseline values, C57BL/6 mice exhibited increased slow-wave sleep after all three challenges, but BALB/c mice did not. Congenic B6.C-H28c mice, which bear the BALB/c allele for low IFN production on the C57BL/6 genetic background, showed enhanced slow-wave sleep after influenza infection but not after NDV. Exogenous IFN did not enhance slow-wave sleep in either C57BL/6 or BALB/c mice. These data suggest that the If-1 allele may influence the somnogenic responsiveness of mice under some conditions but that additional mechanisms may contribute to sleep enhancement during infectious disease.

  17. Ultrafast photo-induced hidden phases in strained manganite thin films

    Science.gov (United States)

    Zhang, Jingdi; McLeod, A. S.; Zhang, Gu-Feng; Stoica, Vladimir; Jin, Feng; Gu, Mingqiang; Gopalan, Venkatraman; Freeland, John W.; Wu, Wenbin; Rondinelli, James; Wen, Haidan; Basov, D. N.; Averitt, R. D.

    Correlated transition metal oxides (TMOs) are particularly sensitive to external control because of energy degeneracy in a complex energy landscape that promote a plethora of metastable states. However, it remains a grand challenge to actively control and fully explore the rich landscape of TMOs. Dynamic control with pulsed photons can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. In the past, we have demonstrated that mode-selective single-laser-pulse excitation of a strained manganite thin film La2/3Ca1/3MnO3 initiates a persistent phase transition from an emergent antiferromagnetic insulating ground state to a ferromagnetic metallic metastable state. Beyond the photo-induced insulator to metal transition, we recently discovered a new peculiar photo-induced hidden phase, identified by an experimental approach that combines ultrafast pump-probe spectroscopy, THz spectroscopy, X-ray diffraction, cryogenic near-field spectroscopy and SHG probe. This work is funded by the DOE, Office of Science, Office of Basic Energy Science under Award Numbers DE-SC0012375 and DE-SC0012592.

  18. A Lactobacillus rhamnosus strain induces a heme oxygenase dependent increase in Foxp3+ regulatory T cells.

    Directory of Open Access Journals (Sweden)

    Khalil Karimi

    Full Text Available We investigated the consequences of feeding with a Lactobacillus species on the immune environment in GALT, and the role of dendritic cells and heme oxygenase-1 in mediating these responses. Feeding with a specific strain of Lactobacillus rhamnosus induced a significant increase in CD4+CD25+Foxp3+ functional regulatory T cells in GALT. This increase was greatest in the mesenteric lymph nodes and associated with a marked decrease in TNF and IFNγ production. Dendritic cell regulatory function and HO-1 expression was also increased. The increase in Foxp3+ T cells could be prevented by treatment with a heme oxygenase inhibitor. However, neither inhibition of heme oxygenase nor blockade of IL-10 and TGFβ prevented the inhibition of inflammatory cytokine production. In conclusion Lactobacillus feeding induced a tolerogenic environment in GALT. HO-1 was critical to the enhancement of Foxp3+ regulatory T cells while additional, as yet unknown, pathways were involved in the down-regulation of inflammatory cytokine production by T cells.

  19. Desorption of large organic molecules by laser-induced plasmon excitation

    International Nuclear Information System (INIS)

    Lee, I.; Callcott, T.A.

    1991-01-01

    Ejection of large organic molecules from surfaces by laser-induced electronic-excited desorption has attracted considerable interest in recent years. In addition to the importance of this effect for fundamental investigations of the ejection process, this desorption technique has been applied to the study of large, fragile molecules by mass spectrometry. In this paper, we present a new method to induce electronic excitation on the metal surface for the desorption of large organic molecules. 3 refs., 3 figs

  20. Laser-induced production of large carbon-based toroids

    International Nuclear Information System (INIS)

    Lyn, M. Elizabeth; He Jibao; Koplitz, Brent

    2005-01-01

    We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures

  1. Nanoscale multiphase phase field approach for stress- and temperature-induced martensitic phase transformations with interfacial stresses at finite strains

    Science.gov (United States)

    Basak, Anup; Levitas, Valery I.

    2018-04-01

    A thermodynamically consistent, novel multiphase phase field approach for stress- and temperature-induced martensitic phase transformations at finite strains and with interfacial stresses has been developed. The model considers a single order parameter to describe the austenite↔martensitic transformations, and another N order parameters describing N variants and constrained to a plane in an N-dimensional order parameter space. In the free energy model coexistence of three or more phases at a single material point (multiphase junction), and deviation of each variant-variant transformation path from a straight line have been penalized. Some shortcomings of the existing models are resolved. Three different kinematic models (KMs) for the transformation deformation gradient tensors are assumed: (i) In KM-I the transformation deformation gradient tensor is a linear function of the Bain tensors for the variants. (ii) In KM-II the natural logarithms of the transformation deformation gradient is taken as a linear combination of the natural logarithm of the Bain tensors multiplied with the interpolation functions. (iii) In KM-III it is derived using the twinning equation from the crystallographic theory. The instability criteria for all the phase transformations have been derived for all the kinematic models, and their comparative study is presented. A large strain finite element procedure has been developed and used for studying the evolution of some complex microstructures in nanoscale samples under various loading conditions. Also, the stresses within variant-variant boundaries, the sample size effect, effect of penalizing the triple junctions, and twinned microstructures have been studied. The present approach can be extended for studying grain growth, solidifications, para↔ferro electric transformations, and diffusive phase transformations.

  2. Combined model of strain-induced phase transformation and orthotropic damage in ductile materials at cryogenic temperatures

    CERN Document Server

    Garion, Cedric

    2003-01-01

    Ductile materials (like stainless steel or copper) show at cryogenic temperatures three principal phenomena: serrated yielding (discontinuous in terms of dsigma/depsilon), plastic strain-induced phase transformations and evolution of ductile damage. The present paper deals exclusively with the two latter cases. Thus, it is assumed that the plastic flow is perfectly smooth. Both in the case of damage evolution and for the gamma-alpha prime phase transformation, the principal mechanism is related to the formation of plastic strain fields. In the constitutive modeling of both phenomena, a crucial role is played by the accumulated plastic strain, expressed by the Odqvist parameter p. Following the general trends, both in the literature concerning the phase transformation and the ductile damage, it is assumed that the rate of transformation and the rate of damage are proportional to the accumulated plastic strain rate. The gamma-alpha prime phase transformation converts the initially homogenous material to a two-p...

  3. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    Directory of Open Access Journals (Sweden)

    Wang Lin

    2015-01-01

    Full Text Available Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy with alpha/beta phases exhibits various strain rate hardening effects, both failure through adiabatic shear band. Ti-5553 alloy with Widmannstatten microstructure exhibit more obvious strain rate hardening effect, lower critical strain rate for ASB nucleation, compared with the alloy with Bimodal microstructures. Under dynamic compression, shock-induced beta to alpha” martensite transformation occurs.

  4. WE-EF-210-06: Ultrasound 2D Strain Measurement of Radiation-Induced Toxicity: Phantom and Ex Vivo Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T; Torres, M; Rossi, P; Jani, A; Curran, W; Yang, X [Emory Univ, Atlanta, GA (United States)

    2015-06-15

    Purpose: Radiation-induced fibrosis is a common long-term complication affecting many patients following cancer radiotherapy. Standard clinical assessment of subcutaneous fibrosis is subjective and often limited to visual inspection and palpation. Ultrasound strain imaging describes the compressibility (elasticity) of biological tissues. This study’s purpose is to develop a quantitative ultrasound strain imaging that can consistently and accurately characterize radiation-induce fibrosis. Methods: In this study, we propose a 2D strain imaging method based on deformable image registration. A combined affine and B-spline transformation model is used to calculate the displacement of tissue between pre-stress and post-stress B-mode image sequences. The 2D displacement is estimated through a hybrid image similarity measure metric, which is a combination of the normalized mutual information (NMI) and normalized sum-of-squared-differences (NSSD). And 2D strain is obtained from the gradient of the local displacement. We conducted phantom experiments under various compressions and compared the performance of our proposed method with the standard cross-correlation (CC)- based method using the signal-to-noise (SNR) and contrast-to-noise (CNS) ratios. In addition, we conducted ex-vivo beef muscle experiment to further validate the proposed method. Results: For phantom study, the SNR and CNS values of the proposed method were significantly higher than those calculated from the CC-based method under different strains. The SNR and CNR increased by a factor of 1.9 and 2.7 comparing to the CC-based method. For the ex-vivo experiment, the CC-based method failed to work due to large deformation (6.7%), while our proposed method could accurately detect the stiffness change. Conclusion: We have developed a 2D strain imaging technique based on the deformable image registration, validated its accuracy and feasibility with phantom and ex-vivo data. This 2D ultrasound strain imaging

  5. Immunohistochemical characterisation of the local immune response in azoxymethane-induced colon tumours in the BDIX inbred rat strain

    DEFF Research Database (Denmark)

    Kobæk Larsen, Morten; Diederichsen, Axel Cosmus Pyndt; Agger, Ralf

    2004-01-01

    by four weekly subcutaneous azoxymethane injections in inbred rats of the BDIX/OrlIco strain in two separate studies. Azoxymethane-induced tumours show many similarities to spontaneously occurring human colon carcinomas with respect to histopathological appearance. In our studies, the overall inflammatory...

  6. Creation of High Mobility Two-Dimensional Electron Gases via Strain Induced Polarization at an Otherwise Nonpolar Complex Oxide Interface

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Trier, Felix; Kasama, Takeshi

    2015-01-01

    The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based heterostructures provides new opportunities for nanoelectronics. Herein, we create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Rem...

  7. Strains of bacterial species induce a greatly varied acute adaptive immune response: The contribution of the accessory genome.

    Directory of Open Access Journals (Sweden)

    Uri Sela

    2018-01-01

    Full Text Available A fundamental question in human susceptibility to bacterial infections is to what extent variability is a function of differences in the pathogen species or in individual humans. To focus on the pathogen species, we compared in the same individual the human adaptive T and B cell immune response to multiple strains of two major human pathogens, Staphylococcus aureus and Streptococcus pyogenes. We found wide variability in the acute adaptive immune response induced by various strains of a species, with a unique combination of activation within the two arms of the adaptive response. Further, this was also accompanied by a dramatic difference in the intensity of the specific protective T helper (Th response. Importantly, the same immune response differences induced by the individual strains were maintained across multiple healthy human donors. A comparison of isogenic phage KO strains, demonstrated that of the pangenome, prophages were the major contributor to inter-strain immune heterogeneity, as the T cell response to the remaining "core genome" was noticeably blunted. Therefore, these findings extend and modify the notion of an adaptive response to a pathogenic bacterium, by implying that the adaptive immune response signature of a bacterial species should be defined either per strain or alternatively to the species' 'core genome', common to all of its strains. Further, our results demonstrate that the acquired immune response variation is as wide among different strains within a single pathogenic species as it is among different humans, and therefore may explain in part the clinical heterogeneity observed in patients infected with the same species.

  8. The effect of air permeability characteristics of protective garments on the induced physiological strain under exercise-heat stress.

    Science.gov (United States)

    Epstein, Yoram; Heled, Yuval; Ketko, Itay; Muginshtein, Jeni; Yanovich, Ran; Druyan, Amit; Moran, Daniel S

    2013-08-01

    The high values of thermal resistance (Rct) and/or vapor resistance (Ret) of chemical protective clothing (CPC) induce a considerable thermal stress. The present study compared the physiological strain induced by CPCs and evaluates the relative importance of the fabrics' Rct, Ret, and air permeability in determining heat strain. Twelve young (20-30 years) healthy, heat-acclimated male subjects were exposed fully encapsulated for 3h daily to an exercise-heat stress (35°C and 30% relative humidity, walking on a motor-driven treadmill at a pace of 5 km h(1) and a 4% inclination, in a work-rest cycle of 45 min work and 15 min rest). Two bipack CPCs (PC1 and PC2) were tested and the results were compared with those attained by two control suits-a standard cotton military BDU (CO1) and an impermeable material suit (CO2). The physiological burden imposed by the two bilayer garments was within the boundaries set by the control conditions. Overall, PC2 induced a lower strain, which was closer to CO1, whereas PC1 was closer to CO2. Air permeability of the PC2 cloth was almost three times higher than that of PC1, enabling a better heat dissipation and consequently a lower physiological strain. Furthermore, air permeability characteristic of the fabrics, which is associated with its construction and weave, significantly correlated with the physiological strain, whereas the correlation with Rct, Ret, and weight was poor. The results emphasize the importance of air permeability in reducing the physiological strain induced by CPCs.

  9. Uniaxial Strain Induced Critical Current Degradation of Ag-Sheathed Bi-2212 Round Wire

    NARCIS (Netherlands)

    Dai, Chao; Qin, Jinggang; Liu, Bo; Liu, Peihang; Wu, Yu; Nijhuis, Arend; Zhou, Chao; Li, Chenshan; Hao, Qingbin; Liu, Sheng

    2018-01-01

    The critical current degradation of Bi-2212 Ag-sheathed round wire subjected to uniaxial strain was studied at 4.2 K in 14 T background field. The strains applied on the sample are both tension and compression. The additional tensile strain caused by the difference in thermal expansion between the

  10. UV light-induced mutability in Salmonella strains containing the umuDC or the mucAB operon

    International Nuclear Information System (INIS)

    Herrera, G.; Urios, A.; Aleixandre, V.; Blanco, M.

    1988-01-01

    Multicopy plasmids carrying either the umuDC operon of Escherichia coli or its analog mucAB operon, were introduced into Ames Salmonella strains in order to analyze the influence of UmuDC and MucAB proteins on repair and mutability after UV irradiation. It was found that in uvr + bacteria, plasmid pICV80:mucAB increased the frequency of UV-induced His + revertants whereas pSE117:umuDC caused a smaller increase in UV mutagenesis. In ΔuvrB bacteria, the protective role of pSE117 against UV killing was weak, and there was a great reduction in the mutant yield. In contrast, in these cells, pICV80 led to a large increase in both cell survival and mutation frequency. These results suggest that in Salmonella, as in E. coli, MucAB proteins mediate UV mutagenesis more efficiently than UmuDC proteins do. Plasmid pICV84:umuD + C - significantly increased UV mutagenesis of TA2659:ΔuvrB cells whereas in them, pICV77:mucA + B - had no effect on mutability indicating the presence in Salmonella TA2659 of a gene functionally homologous to umuC. 18 refs.; 1 figure; 3 tabs

  11. Effect of large compressive strain on low field electrical transport in La0.88Sr0.12MnO3 thin films

    International Nuclear Information System (INIS)

    Prasad, Ravikant; Gaur, Anurag; Siwach, P K; Varma, G D; Kaur, A; Singh, H K

    2007-01-01

    We have investigated the effect of large in-plane compressive strain on the electrical transport in La 0.88 Sr 0.12 MnO 3 in thin films. For achieving large compressive strain, films have been deposited on single crystal LaAlO 3 (LAO, a = 3.798 A) substrate from a polycrystalline bulk target having average in-plane lattice parameter a av = (a b + b b )/2 = 3.925 A. The compressive strain was further relaxed by varying the film thickness in the range ∼6-75 nm. In the film having least thickness (∼6 nm) large increase (c = 3.929 A) in the out-of-plane lattice parameter is observed which gradually decreases towards the bulk value (c bulk = 3.87 A) for ∼75 nm thick film. This shows that the film having the least thickness is under large compressive strain, which partially relaxes with increasing film thickness. The T IM of the bulk target ∼145 K goes up to ∼235 K for the ∼6 nm thin film and even for partially strain relaxed ∼75 nm thick film T IM is as high as ∼200 K. This enhancement in T IM is explained in terms of suppression of Jahn-Teller distortion of the MnO 6 octahedra by the large in-plane compressive strain. We observe a large enhancement in the low field magnetoresistance (MR) just below T IM in the films having partial strain relaxation. Thick films of 6 and 20 nm have MR ∼14% at 3 kOe that almost doubles in 35 nm film to ∼27%. Similar enhancement is also obtained in the case of the temperature coefficient of resistivity. The near doubling of low field MR is explained in terms of delocalization of weakly localized carriers around T IM by small magnetic fields

  12. Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperature. II. Optical strain of remaining stress type

    International Nuclear Information System (INIS)

    Okubo, H.; Yoshii, F.; Kaetsu, I.; Honda, S.

    1978-01-01

    Previously it was found that casting could be carried out efficiently without strain formation by radiation-induced polymerization of glass-forming monomers. Two types of strain were observed in casting: thermal stream type, which was studied previously, and remained stress type. In this report, the effect of various factors on the formation of remaining stress-type strain in radiation-induced casting polymerization was studied. It was found that the molecular weight of prepolymer did not affect strain formation, while prepolymer concentration and viscosity of the system had a serious influence on strain formation. It could be deduced that this type of strain formed as a result of remaining inner stress due to poor relaxation of the shrinking stress. It was realized that less volume shrinkage of glass-forming monomers accompanying casting polymerization reduced the strain formation of this type in radiation-induced casting polymerization at low temperatures

  13. Comparative genomics of 12 strains of Erwinia amylovora identifies a pan-genome with a large conserved core.

    Directory of Open Access Journals (Sweden)

    Rachel A Mann

    Full Text Available The plant pathogen Erwinia amylovora can be divided into two host-specific groupings; strains infecting a broad range of hosts within the Rosaceae subfamily Spiraeoideae (e.g., Malus, Pyrus, Crataegus, Sorbus and strains infecting Rubus (raspberries and blackberries. Comparative genomic analysis of 12 strains representing distinct populations (e.g., geographic, temporal, host origin of E. amylovora was used to describe the pan-genome of this major pathogen. The pan-genome contains 5751 coding sequences and is highly conserved relative to other phytopathogenic bacteria comprising on average 89% conserved, core genes. The chromosomes of Spiraeoideae-infecting strains were highly homogeneous, while greater genetic diversity was observed between Spiraeoideae- and Rubus-infecting strains (and among individual Rubus-infecting strains, the majority of which was attributed to variable genomic islands. Based on genomic distance scores and phylogenetic analysis, the Rubus-infecting strain ATCC BAA-2158 was genetically more closely related to the Spiraeoideae-infecting strains of E. amylovora than it was to the other Rubus-infecting strains. Analysis of the accessory genomes of Spiraeoideae- and Rubus-infecting strains has identified putative host-specific determinants including variation in the effector protein HopX1(Ea and a putative secondary metabolite pathway only present in Rubus-infecting strains.

  14. X-ray-induced mutations in Escherichia coli K-12 strains with altered DNA polymerase I activities

    International Nuclear Information System (INIS)

    Nagata, Yuki; Kawata, Masakado; Komura, Jun-ichiro; Ono, Tetsuya; Yamamoto, Kazuo

    2003-01-01

    Spectra of ionizing radiation mutagenesis were determined by sequencing X-ray-induced endogenous tonB gene mutations in Escherichia coli polA strains. We used two polA alleles, the polA1 mutation, defective for Klenow domain, and the polA107 mutation, defective for flap domain. We demonstrated that irradiation of 75 and 50 Gy X-rays could induce 3.8- and 2.6-fold more of tonB mutation in polA1 and polA107 strains, respectively, than spontaneous level. The radiation induced spectrum of 51 tonB mutations in polA1 and 51 in polA107 indicated that minus frameshift, A:T→T:A transversion and G:C→T:A transversion were the types of mutations increased. Previously, we have reported essentially the same X-ray-induced tonB mutation spectra in the wild-type strain. These results indicate that (1) X-rays can induce minus frameshift, A:T→T:A transversion and G:C→T:A transversion in E. coli and (2) presence or absence of polymerase I (PolI) of E. coli does not have any effects on the process of X-ray mutagenesis

  15. Strain and thermally induced magnetic dynamics and spin current in magnetic insulators subject to transient optical grating

    Science.gov (United States)

    Wang, Xi-Guang; Chotorlishvili, Levan; Berakdar, Jamal

    2017-07-01

    We analyze the magnetic dynamics and particularlythe spin current in an open-circuit ferromagnetic insulator irradiated by two intense, phase-locked laser pulses. The interference of the laser beams generates a transient optical grating and a transient spatio-temporal temperature distribution. Both effects lead to elastic and heat waves at the surface and into the bulk of the sample. The strain induced spin current as well as the thermally induced magnonic spin current are evaluated numerically on the basis of micromagnetic simulations using solutions of the heat equation. We observe that the thermo-elastically induced magnonic spin current propagates on a distance larger than the characteristic size of thermal profile, an effect useful for applications in remote detection of spin caloritronics phenomena. Our findings point out that exploiting strain adds a new twist to heat-assisted magnetic switching and spin-current generation for spintronic applications.

  16. Hydrogen embrittlement of austenitic stainless steels revealed by deformation microstructures and strain-induced creation of vacancies

    International Nuclear Information System (INIS)

    Hatano, M.; Fujinami, M.; Arai, K.; Fujii, H.; Nagumo, M.

    2014-01-01

    Hydrogen embrittlement of austenitic stainless steels has been examined with respect to deformation microstructures and lattice defects created during plastic deformation. Two types of austenitic stainless steels, SUS 304 and SUS 316L, uniformly hydrogen-precharged to 30 mass ppm in a high-pressure hydrogen environment, are subjected to tensile straining at room temperature. A substantial reduction of tensile ductility appears in hydrogen-charged SUS 304 and the onset of fracture is likely due to plastic instability. Fractographic features show involvement of plasticity throughout the crack path, implying the degradation of the austenitic phase. Electron backscatter diffraction analyses revealed prominent strain localization enhanced by hydrogen in SUS 304. Deformation microstructures of hydrogen-charged SUS 304 were characterized by the formation of high densities of fine stacking faults and ε-martensite, while tangled dislocations prevailed in SUS 316L. Positron lifetime measurements have revealed for the first time hydrogen-enhanced creation of strain-induced vacancies rather than dislocations in the austenitic phase and more clustering of vacancies in SUS 304 than in SUS 316L. Embrittlement and its mechanism are ascribed to the decrease in stacking fault energies resulting in strain localization and hydrogen-enhanced creation of strain-induced vacancies, leading to premature fracture in a similar way to that proposed for ferritic steels

  17. Nitric oxide (NO) production in mammalian non-tumorigenic epithelial cells of the small intestine and macrophages induced by individual strains of lactobacilli and bifidobacteria

    DEFF Research Database (Denmark)

    Pipenbaher, Natasa; Møller, Peter Lange; Dolinsek, Jan

    2009-01-01

    and absence of interferon gamma (INF-¿). Production of NO in intestinal epithelium was stimulated by individual strains of lactobacilli without INF-¿ priming. While none of the tested bifidobacteria were capable of inducing NO production, most constitutively secreted NO. Most tested strains induced...

  18. Large piezoelectric strain with ultra-low strain hysteresis in highly c-axis oriented Pb(Zr0.52Ti0.48)O3 films with columnar growth on amorphous glass substrates.

    Science.gov (United States)

    Nguyen, Minh D; Houwman, Evert P; Rijnders, Guus

    2017-10-10

    Thin films of PbZr 0 . 52 Ti 0 . 48 O 3 (PZT) with largely detached columnar grains, deposited by pulsed laser deposition (PLD) on amorphous glass substrates covered with Ca 2 Nb 3 O 10 nanosheets as growth template and using LaNiO 3 electrode layers, are shown to exhibit very high unipolar piezoelectric strain and ultra-low strain hysteresis. The observed increase of the piezoelectric coefficient with increasing film thickness is attributed to the reduction of clamping, because of the increasingly less dense columnar microstructure (more separation between the grains) with across the film thickness. A very large piezoelectric coefficient (490 pm/V) and a high piezoelectric strain (~0.9%) are obtained in 4-µm-thick film under an applied electric field of 200 kV/cm, which is several times larger than in usual PZT ceramics. Further very low strain hysteresis (H≈2-4%) is observed in 4 to 5 µm thick films. These belong to the best values demonstrated so far in piezoelectric films. Fatigue testing shows that the piezoelectric properties are stable up to 10 10 cycles. The growth of high quality PZT films with very large strain and piezoelectric coefficients, very low hysteresis and with long-term stability on a technologically important substrate as glass is of great significance for the development of practical piezo driven microelectromechanical actuator systems.

  19. Control of superconductivity by means of electric-field-induced strain in superconductor/piezoelectric hybrids

    Science.gov (United States)

    Stamopoulos, D.; Zeibekis, M.; Zhang, S. J.

    2018-01-01

    The controlled modification of superconductivity by any means, specifically in hybrid systems, has attracted much interest in the recent decades. Here, we present experimental data and phenomenological modeling on the control of TC of superconducting (SC) Nb thin films, with thickness 3 nm ≤ dN b≤50 nm, under the application of in-plane strain, S(Eex) induced by an external out-of-plane electric field, Eex to piezoelectric (PE) single crystals, namely, ( 1 -x )Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT), with x = 0.27 and 0.31. We report experimental modification of TC of Nb by Eex, accurately described by a phenomenological model that incorporates the constitutive relation S(Eex) of PMN-xPT. The systematic experimental-phenomenological modeling approach introduced here is generic and paves the way for an understanding of the underlying physical mechanisms in any SC/PE hybrid.

  20. Chiral Anomaly from Strain-Induced Gauge Fields in Dirac and Weyl Semimetals

    Directory of Open Access Journals (Sweden)

    D. I. Pikulin

    2016-10-01

    Full Text Available Dirac and Weyl semimetals form an ideal platform for testing ideas developed in high-energy physics to describe massless relativistic particles. One such quintessentially field-theoretic idea of the chiral anomaly already resulted in the prediction and subsequent observation of the pronounced negative magnetoresistance in these novel materials for parallel electric and magnetic fields. Here, we predict that the chiral anomaly occurs—and has experimentally observable consequences—when real electromagnetic fields E and B are replaced by strain-induced pseudo-electromagnetic fields e and b. For example, a uniform pseudomagnetic field b is generated when a Weyl semimetal nanowire is put under torsion. In accordance with the chiral anomaly equation, we predict a negative contribution to the wire resistance proportional to the square of the torsion strength. Remarkably, left- and right-moving chiral modes are then spatially segregated to the bulk and surface of the wire forming a “topological coaxial cable.” This produces hydrodynamic flow with potentially very long relaxation time. Another effect we predict is the ultrasonic attenuation and electromagnetic emission due to a time-periodic mechanical deformation causing pseudoelectric field e. These novel manifestations of the chiral anomaly are most striking in the semimetals with a single pair of Weyl nodes but also occur in Dirac semimetals such as Cd_{3}As_{2} and Na_{3}Bi and Weyl semimetals with unbroken time-reversal symmetry.

  1. Chiral Anomaly from Strain-Induced Gauge Fields in Dirac and Weyl Semimetals

    Science.gov (United States)

    Pikulin, D. I.; Chen, Anffany; Franz, M.

    2016-10-01

    Dirac and Weyl semimetals form an ideal platform for testing ideas developed in high-energy physics to describe massless relativistic particles. One such quintessentially field-theoretic idea of the chiral anomaly already resulted in the prediction and subsequent observation of the pronounced negative magnetoresistance in these novel materials for parallel electric and magnetic fields. Here, we predict that the chiral anomaly occurs—and has experimentally observable consequences—when real electromagnetic fields E and B are replaced by strain-induced pseudo-electromagnetic fields e and b . For example, a uniform pseudomagnetic field b is generated when a Weyl semimetal nanowire is put under torsion. In accordance with the chiral anomaly equation, we predict a negative contribution to the wire resistance proportional to the square of the torsion strength. Remarkably, left- and right-moving chiral modes are then spatially segregated to the bulk and surface of the wire forming a "topological coaxial cable." This produces hydrodynamic flow with potentially very long relaxation time. Another effect we predict is the ultrasonic attenuation and electromagnetic emission due to a time-periodic mechanical deformation causing pseudoelectric field e . These novel manifestations of the chiral anomaly are most striking in the semimetals with a single pair of Weyl nodes but also occur in Dirac semimetals such as Cd3 As2 and Na3Bi and Weyl semimetals with unbroken time-reversal symmetry.

  2. 3D characterization of coal strains induced by compression, carbon dioxide sorption, and desorption at in-situ stress conditions

    International Nuclear Information System (INIS)

    Pone, J. Denis N.; Halleck, Phillip M.; Mathews, Jonathan P.

    2010-01-01

    Sequestration of carbon dioxide in unmineable coal seams is an option to combat climate change and an opportunity to enhance coalbed methane production. Prediction of sequestration potential in coal requires characterization of porosity, permeability, sorption capacity and the magnitude of swelling due to carbon dioxide uptake or shrinkage due to methane and water loss. Unfortunately, the majority of data characterizing coal-gas systems have been obtained from powdered, unconfined coal samples. Little is known about confined coal behavior during carbon dioxide uptake and methane desorption. The present work focuses on the characterization of lithotype specific deformation, and strain behavior during CO 2 uptake at simulated in-situ stress conditions. It includes the evaluation of three-dimensional strain induced by the confining stress, the sorption, and the desorption of carbon dioxide. X-ray computed tomography allowed three-dimensional characterization of the bituminous coal deformation samples under hydrostatic stress. The application of 6.9 MPa of confining stress contributes an average of - 0.34% volumetric strain. Normal strains due to confining stress were - 0.08%, - 0.15% and - 0.11% along the x, y and z axes respectively. Gas injection pressure was 3.1 MPa and the excess sorption was 0.85 mmol/g. Confined coal exposed to CO 2 for 26 days displays an average volumetric expansion of 0.4%. Normal strains due to CO 2 sorption were 0.11%, 0.22% and 0.11% along x, y and z axes. Drainage of the CO 2 induced an average of - 0.33% volumetric shrinkage. Normal strains due to CO 2 desorption were - 0.23%, - 0.08% and - 0.02% along x, y and z axes. Alternating positive and negative strain values observed along the sample length during compression, sorption and desorption respectively emphasized that both localized compression/compaction and expansion of coal will occur during CO 2 sequestration. (author)

  3. Absence of ultraviolet-inducible DNA polymerase I-like activity in Escherichia coli strains harbouring R plasmids

    International Nuclear Information System (INIS)

    Upton, C.; Pinney, R.J.

    1981-01-01

    No DNA polymerase I-like activity was found associated with the ultraviolet (u.v.)-protecting plasmids R205, R46 or pKM101 in either uninduced or u.v.-induced wild-type or DNA polymerase I-deficient strains of Escherichia coli. Nor was any plasmid-associated polymerase activity detectable in similar systems containing u.v.-irradiated DNA as template. However, plasmids R205, R46 and pKM 101 still increased survival and mutagenesis of the polymerase I-deficient E. coli strain after u.v. irradiation. (author)

  4. Semi-solid process of 2024 wrought aluminum alloy by strain induced melt activation

    Directory of Open Access Journals (Sweden)

    Surachai Numsarapatnuk

    2013-10-01

    Full Text Available The aim of this study is to develop a production process of a fine globular structure feedstock of the 2024 aluminumalloy suitable for subsequent semi-solid forming. The 2024 wrought aluminum alloy was first annealed to reduce the effect ofwork hardening. Then, strain was induced in the alloy by cold compression. After that the microstructural evolution duringpartial melting was investigated. The samples were subjected to full annealing at 415°C for 3 hrs prior to cold compression of40% reduction of area (RA with 3 mm/min strain rate. After that samples were partially melted at 620°C with varying holdingtime from 0 to 60 min followed by water quenching. The grain size and the average grain diameter of solid grains weremeasured using the linear intercept method. The globularization was interpreted in terms of shape factor. Liquid fraction andthe distribution of the eutectic liquid was also investigated. It was found that during partial melting, the globular morphologywas formed by the liquid wetting and fragmentation of high angle boundaries of recrystallized grains. The suitable semi-solidmicrostructure was obtained from a condition of full annealing, 40% cold working and partial melting at 620°C for 6 minholding time. The near globular grains obtained in the range of 0-60 min consisted of uniform spheroid grains with an averagegrain diameter ranged from 73 to 121 m, quenched liquid fraction was approximately 13–27% and the shape factor was greaterthan 0.6. At a holding time of less than 6 min, grain coarsening was dominant by the immigration of high-angle grainboundaries. At a longer holding time, liquid fraction increased and Ostwald ripening was dominant. The coarsening rateconstant for the 2024 Al alloy was 400.36 mm3.s-1. At a soaking time of 60 min, it was found that a minimum diameter differencewas 1.06% with coarsening index n=3 in a power law equation. The non-dendritic slug of 2024 alloy was rapid compressedinto a disc with 90%RA

  5. Large piezoelectric strain with ultra-low strain hysteresis in highly c-axis oriented Pb(Zr0.52Ti0.48)O3 films with columnar growth on amorphous glass substrates

    NARCIS (Netherlands)

    Nguyen, Minh D.; Houwman, Evert P.; Rijnders, Guus

    2017-01-01

    Thin films of PbZr0.52Ti0.48O3 (PZT) with largely detached columnar grains, deposited by pulsed laser deposition (PLD) on amorphous glass substrates covered with Ca2Nb3O10 nanosheets as growth template and using LaNiO3 electrode layers, are shown to exhibit very high unipolar piezoelectric strain

  6. Discovery of a new strain of murine rotavirus that is consistently shed in large quantities after oral inoculation of adult mice

    International Nuclear Information System (INIS)

    McNeal, Monica M.; Belli, Janine; Basu, Mitali; Choi, Anthony H.-C.; Ward, Richard L.

    2004-01-01

    In 1990, we developed the adult mouse model for studies on active immunity against shedding of the EDIM strain of murine rotavirus. Low and inconsistent levels of EDIM shedding in some strains of adult mice, particularly those on C57BL/6 backgrounds, established the need for an alternative murine rotavirus strain for these studies. Fortuitously, such a rotavirus strain was obtained from mice housed within the conventional colony at Children's Hospital. This strain, named EMcN, was clearly distinguishable from EDIM based on electropherotype. Furthermore, sequence analyses of VP4 and VP7 genes of EMcN revealed non-identities in 5% of the amino acids of both proteins relative to EDIM but established EMcN as another G3P[16] strain of murine rotavirus. Subgroup analysis showed EMcN belonged to SG1 while EDIM was found to be non-SG1/SG2. Similarly, unlike EDIM, the EMcN strain was identified as serotype G3 based on neutralization by hyperimmune antisera developed against prototype human and simian G3 rotavirus strains. Although EDIM produced more days of diarrhea and was shed in greater quantities in neonatal BALB/c mice, EMcN was shed in much greater quantities in adult BALB/c mice. More importantly, in contrast to the EDIM strain, EMcN was shown to be consistently shed in large quantities in adult C57BL/6 mice and ko mice on this background. Therefore, it is recommended that the EMcN strain be used for future challenge studies with mice on this background

  7. A thermodynamically consistent model of magneto-elastic materials under diffusion at large strains and its analysis

    Science.gov (United States)

    Roubíček, Tomáš; Tomassetti, Giuseppe

    2018-06-01

    A theory of elastic magnets is formulated under possible diffusion and heat flow governed by Fick's and Fourier's laws in the deformed (Eulerian) configuration, respectively. The concepts of nonlocal nonsimple materials and viscous Cahn-Hilliard equations are used. The formulation of the problem uses Lagrangian (reference) configuration while the transport processes are pulled back. Except the static problem, the demagnetizing energy is ignored and only local non-self-penetration is considered. The analysis as far as existence of weak solutions of the (thermo) dynamical problem is performed by a careful regularization and approximation by a Galerkin method, suggesting also a numerical strategy. Either ignoring or combining particular aspects, the model has numerous applications as ferro-to-paramagnetic transformation in elastic ferromagnets, diffusion of solvents in polymers possibly accompanied by magnetic effects (magnetic gels), or metal-hydride phase transformation in some intermetallics under diffusion of hydrogen accompanied possibly by magnetic effects (and in particular ferro-to-antiferromagnetic phase transformation), all in the full thermodynamical context under large strains.

  8. Thermal Annealing induced relaxation of compressive strain in porous GaN structures

    KAUST Repository

    Ben Slimane, Ahmed

    2012-01-01

    The effect of annealing on strain relaxation in porous GaN fabricated using electroless chemical etching is presented. The Raman shift of 1 cm-1 in phonon frequency of annealed porous GaN with respect to as-grown GaN corresponds to a relaxation of compressive strain by 0.41 ± 0.04 GPa. The strain relief promises a marked reduction in threading dislocation for subsequent epitaxial growth.

  9. Coalescence of DNA Double Strand Breaks Induced by Galactic Cosmic Radiation is Modulated by Genetics in 15 Inbred Strains of Mice

    Science.gov (United States)

    Penninckx, Sebastien; Ray, Shayoni; Staatz, Kevin; Degorre, Charlotte; Guiet, Elodie; Viger, Louise; Snijders, Antoine M.; Mao, Jian-Hua; Karpen, Gary; Costes, Sylvain V.

    2018-01-01

    In this manuscript we address the challenges associated with the ability to predict radiation sensitivity associated with exposure to either cosmic radiation or X-rays in a population study, by monitoring DNA damage sensing protein 53BP1 forming small nuclear radiation-induced foci (RIF) as a surrogate biomarker of DNA double strand breaks (DSB). 76 primary skin fibroblasts were isolated from 10 collaborative cross strains and five reference inbred mice (C57Bl/6, BALB/CByJ, B6C3, C3H and CBA/CaJ) and exposed to three different charged nuclei of increasing LET (350 MeV/n Si, 350 MeV/n Ar and 600 MeV/n Fe) and X-ray. Our data brings strong evidence against the classic "contact-first" model where DSBs are assumed to be immobile and repaired at the lesion site. In contrast, our model suggests nearby DSBs move into single repair unit characterized by large RIF before the repair machinery kicks in. Such model has the advantage of being much more efficient molecularly but is poorly suited to deal with cosmic radiation, where energy is concentrated along the particle trajectory, inducing a large density of DSBs along each particle track. In accordance with this model, RIF quantification after X-ray exposition showed a saturated dose response for early time points post-irradiation for all strains. Similarly, the high-LET response showed that RIF number matched the number of track per cell, not the number of expected DSB per cell (1). At the temporal level, we noted that the percentage of unrepaired high-LET tracks over a 48 hour time-course increased with LET, confirming that the DNA repair process becomes more difficult as more DSB coalesce into single RIF. There was also good agreement between persistent RIF levels measured in-vitro in the primary skin cultures and survival levels of T-cells and B-cells collected in blood samples from 10 CC strains 24 hours after 0.1 Gy whole-body dose of X-ray. This suggests that persistent RIF 24 hour post-IR is a good surrogate in

  10. Field-induced strain memory with non-180 .deg. domain-reorientation control

    International Nuclear Information System (INIS)

    Kadota, Yoichi; Hosaka, Hiroshi; Morita, Takeshi

    2010-01-01

    Using non-180 .deg. domain-reorientation control, we propose the strain memory effect in ferroelectric ceramics. Electric fields with asymmetric amplitudes were applied to soft-type lead zirconate titanate (PZT) ceramics, and the strain hysteresis and the polarization loop were measured. The butterfly curve became asymmetric under an electric field with a particular asymmetric amplitude. The asymmetric butterfly curve had two stable strain states at zero electric field. Thus, the strain memory effect was realized as the difference between the two stable strain states. An XRD analysis was carried out to verify the contribution of the non-180 .deg. domain reorientation to the strain memory effect. The non-180 .deg. domain reorientation was determined as the intensity ratio of the (002) to the (200) peak. The strain memory determined from macroscopic strain measurements had a linear relationship to the non-180 .deg. domain volume fraction. This result indicated the origin of the strain memory to be the non-180 .deg. domain reorientation.

  11. Optical properties and optimization of electromagnetically induced transparency in strained InAs/GaAs quantum dot structures

    DEFF Research Database (Denmark)

    Barettin, D.; Houmark-Nielsen, Jakob; Lassen, B.

    2009-01-01

    comparing four different k center dot p band-structure models. In addition to the separation of the heavy and light holes due to the biaxial-strain component, we observe a general reduction in the transition strengths due to energy crossings in the valence bands caused by strain and band-mixing effects. We......Using multiband k center dot p theory we study the size and geometry dependence on the slow light properties of conical semiconductor quantum dots. We find the V-type scheme for electromagnetically induced transparency (EIT) to be most favorable and identify an optimal height and size for efficient...... EIT operation. In case of the ladder scheme, the existence of additional dipole allowed intraband transitions along with an almost equidistant energy-level spacing adds additional decay pathways, which significantly impairs the EIT effect. We further study the influence of strain and band mixing...

  12. Dominant phonon wave vectors and strain-induced splitting of the 2D Raman mode of graphene

    Science.gov (United States)

    Narula, Rohit; Bonini, Nicola; Marzari, Nicola; Reich, Stephanie

    2012-03-01

    The dominant phonon wave vectors q* probed by the 2D Raman mode of pristine and uniaxially strained graphene are determined via a combination of ab initio calculations and a full two-dimensional integration of the transition matrix. We show that q* are highly anisotropic and rotate about K with the polarizer and analyzer condition relative to the lattice. The corresponding phonon-mediated electronic transitions show a finite component along K-Γ that sensitively determines q*. We invalidate the notion of “inner” and “outer” processes. The characteristic splitting of the 2D mode of graphene under uniaxial tensile strain and given polarizer and analyzer setting is correctly predicted only if the strain-induced distortion and red-shift of the in-plane transverse optical (iTO) phonon dispersion as well as the changes in the electronic band structure are taken into account.

  13. Genetic sexing strains in Mediterranean fruit fly, an example for other species amenable to large-scale rearing for the sterile insect technique

    International Nuclear Information System (INIS)

    Franz, G.

    2005-01-01

    Through genetic and molecular manipulations, strains can be developed that are more suitable for the sterile insect technique (SIT). In this chapter the development of genetic sexing strains (GSSs) is given as an example. GSSs increase the effectiveness of area-wide integrated pest management (AW-IPM) programmes that use the SIT by enabling the large-scale release of only sterile males. For species that transmit disease, the removal of females is mandatory. For the Mediterranean fruit fly Ceratitis capitata (Wiedemann), genetic sexing systems have been developed; they are stable enough to be used in operational programmes for extended periods of time. Until recently, the only way to generate such strains was through Mendelian genetics. In this chapter, the basic principle of translocation-based sexing strains is described, and Mediterranean fruit fly strains are used as examples to indicate the problems encountered in such strains. Furthermore, the strategies used to solve these problems are described. The advantages of following molecular strategies in the future development of sexing strains are outlined, especially for species where little basic knowledge of genetics exists. (author)

  14. Method for generation of THz frequency radiation and sensing of large amplitude material strain waves in piezoelectric materials

    Science.gov (United States)

    Reed, Evan J.; Armstrong, Michael R.

    2010-09-07

    Strain waves of THz frequencies can coherently generate radiation when they propagate past an interface between materials with different piezoelectric coefficients. Such radiation is of detectable amplitude and contains sufficient information to determine the time-dependence of the strain wave with unprecedented subpicosecond, nearly atomic time and space resolution.

  15. Exercise-induced changes in left ventricular global longitudinal strain in asymptomatic severe aortic stenosis.

    Science.gov (United States)

    Lech, Agnieszka K; Dobrowolski, Piotr P; Klisiewicz, Anna; Hoffman, Piotr

    2017-01-01

    The management of patients with asymptomatic severe aortic stenosis (ASAS) is still under discussion. Therefore, it is advisable to search for the parameters of early damage to left ventricular (LV) function. The aim of the study was to assess exercise-induced changes in LV global longitudinal strain (GLS) in ASAS. The ASAS group consisted of 50 patients (26 women and 24 men, aged 38.4 ± 18.1 years) meeting the echocardiographic criteria of severe aortic stenosis (AVA 4 m/s, mean aortic gradient > 40 mm Hg), with normal LV ejection fraction (LVEF ≥ 55%) and sinus rhythm on electrocardiogram, and without significant concomitant valvular heart diseases. The control group consisted of 21 people matched for age and sex. Echocardiographic examinations and echocardiographic stress tests with the assessment of GLS using the speckle tracking imaging were performed. The ASAS group was characterised by statistically significantly higher LV mass index (LVMI) and higher LVEF. GLS values at rest in both groups were within normal limits but were significantly higher in the control group (-18.9 ± 2.4% vs. -20.7 ± 1.7%, p = 0.006). An increase in GLS at peak exercise in both groups was observed, lower in the ASAS group (the difference was not statistically significant: -0.8 ± 3.0% vs. -2.2 ± 3.1%, p = 0.086). Changes in GLS during exercise (ΔGLS) did not correlate with the parameters of the severity of aortic stenosis. In the multivariate model, LVMI proved to be a factor associated with GLS at rest and during exercise. In patients with ASAS, GLS is a non-invasive marker of an early stage of LV myocardial damage associated with myocardial hypertrophy. An increase in GLS during exercise in the ASAS group, smaller than in the control group, indicates a preserved functional reserve of the LV myocardium but smaller than in healthy individuals. The assessment of the clinical usefulness of exercise-induced changes in GLS requires further research.

  16. Cytokine production induced by non-encapsulated and encapsulated Porphyromonas gingivalis strains

    NARCIS (Netherlands)

    Kunnen, A.; Dekker, D.C.; van Pampus, M.G.; Harmsen, H.J.; Aarnoudse, J.G.; Abbas, F.; Faas, M.M.

    Objective: Although the exact reason is not known, encapsulated gram-negative Porphyromonas gingivalis strains are more virulent than non-encapsulated strains. Since difference in virulence properties may be due to difference in cytokine production following recognition of the bacteria or their

  17. Strain differences of cadmium-induced hepatotoxicity in Wistar-Imamichi and Fischer 344 rats: involvement of cadmium accumulation

    International Nuclear Information System (INIS)

    Shimada, Hideaki; Takamure, Yasutaka; Shimada, Akinori; Yasutake, Akira; Waalkes, Michael P.; Imamura, Yorishige

    2004-01-01

    We previously reported that Wistar-Imamichi (WI) rats have a strong resistance to cadmium (Cd)-induced lethality compared to other strains such as Fischer 344 (Fischer) rats. The present study was designed to establish biochemical and histological differences in Cd toxicity in WI and Fischer rats, and to clarify the mechanistic basis of these strain differences. A single Cd (4.5 mg/kg, s.c.) treatment caused a significant increase in serum alanine aminotransferase activity, indicative of hepatotoxicity, in Fischer rats, but did not in WI rats. This difference in hepatotoxic response to Cd was supported by pathological analysis. After treatment with Cd at doses of 3.0, 3.5 and 4.5 mg/kg, the hepatic and renal accumulation of Cd was significantly lower in the WI rats than in the Fischer rats, indicating a kinetic mechanism for the observed strain differences in Cd toxicity. Thus, the remarkable resistance to Cd-induced hepatotoxicity in WI rats is associated, at least in part, with a lower tissue accumulation of the metal. Hepatic and renal zinc (Zn) contents after administration were similarly lower in WI than in Fischer rats. When Zn was administered in combination with Cd to Fischer rats, it decreased Cd contents in the liver and kidney, and exhibited a significant protective effect against the toxicity of Cd. We propose the possibility that Zn transporter plays an important role in the strain difference of Cd toxicity in WI and Fischer rats

  18. Fiber Bragg grating based spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples

    International Nuclear Information System (INIS)

    Latka, Ines; Habisreuther, Tobias; Litzkendorf, Doris

    2011-01-01

    Highlights: → Fiber Bragg gratings (FBG) act as strain sensors, also at cryogenic temperatures. → FBGs are not sensitive to magnetic fields. → Local, shape dependent magnetostriction was detected on rectangular samples. → Magnetostrictive effects of the top surface and in a gap between two samples are different. - Abstract: We report on measurements of the spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples. The spatially resolved strain measurements are accomplished by the use 2 fiber Bragg grating arrays, which are with an included angle of 45 o fixed to the surface. In this paper first attempts to confirm the shape distortions caused by the flux-pinning induced strain as predicted in will be presented. Two sample setups, a single bulk and a 'mirror' arrangement, will be compared. This mirror setup represents a model configuration for a measurement inside the superconductor, where demagnetization effects can be neglected and the magnetic field merely has a z-component.

  19. Computer simulation of strain-induced ordering in interstitial solutions based on the b.c.c. Ta lattice

    International Nuclear Information System (INIS)

    Blanter, M.S.; Khachaturyan, A.G.

    1980-01-01

    A computer simulation is made of strain-induced ordering of interstitial atoms within octahedral interstices in the Ta host lattice. The calculation technique allows to take into account infinite-range strain-induced interaction. Computer simulation of ordering process enables to model the sequence of structure changes which occur during the ordering process and to find the equilibrium structure of the stable interstitial superstructures. The structures of high-temperature ordering phases obtained by the method of static concentration waves coincide with those obtained by means of computer simulation. However computer simulation enables to predict the structures of low-temperature ordered phases which cannot be obtained by the method of concentration waves. Comparison of computer simulation results and structures of observed ordered phases demonstrates good agreement. (author)

  20. Tbc1d1 mutation in lean mouse strain confers leanness and protects from diet-induced obesity

    DEFF Research Database (Denmark)

    Chadt, Alexandra; Leicht, Katja; Deshmukh, Atul

    2008-01-01

    We previously identified Nob1 as a quantitative trait locus for high-fat diet-induced obesity and diabetes in genome-wide scans of outcross populations of obese and lean mouse strains. Additional crossbreeding experiments indicated that Nob1 represents an obesity suppressor from the lean Swiss Jim...... Lambert (SJL) strain. Here we identify a SJL-specific mutation in the Tbc1d1 gene that results in a truncated protein lacking the TBC Rab-GTPase-activating protein domain. TBC1D1, which has been recently linked to human obesity, is related to the insulin signaling protein AS160 and is predominantly...... and reduced glucose uptake in isolated skeletal muscle. Our data strongly suggest that mutation of Tbc1d1 suppresses high-fat diet-induced obesity by increasing lipid use in skeletal muscle....

  1. Characterization of a Large Antibiotic Resistance Plasmid Found in Enteropathogenic Escherichia coli Strain B171 and Its Relatedness to Plasmids of Diverse E. coli and Shigella Strains.

    Science.gov (United States)

    Hazen, Tracy H; Michalski, Jane; Nagaraj, Sushma; Okeke, Iruka N; Rasko, David A

    2017-09-01

    Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe infantile diarrhea in developing countries. Previous research has focused on the diversity of the EPEC virulence plasmid, whereas less is known regarding the genetic content and distribution of antibiotic resistance plasmids carried by EPEC. A previous study demonstrated that in addition to the virulence plasmid, reference EPEC strain B171 harbors a second, larger plasmid that confers antibiotic resistance. To further understand the genetic diversity and dissemination of antibiotic resistance plasmids among EPEC strains, we describe the complete sequence of an antibiotic resistance plasmid from EPEC strain B171. The resistance plasmid, pB171_90, has a completed sequence length of 90,229 bp, a GC content of 54.55%, and carries protein-encoding genes involved in conjugative transfer, resistance to tetracycline ( tetA ), sulfonamides ( sulI ), and mercury, as well as several virulence-associated genes, including the transcriptional regulator hha and the putative calcium sequestration inhibitor ( csi ). In silico detection of the pB171_90 genes among 4,798 publicly available E. coli genome assemblies indicates that the unique genes of pB171_90 ( csi and traI ) are primarily restricted to genomes identified as EPEC or enterotoxigenic E. coli However, conserved regions of the pB171_90 plasmid containing genes involved in replication, stability, and antibiotic resistance were identified among diverse E. coli pathotypes. Interestingly, pB171_90 also exhibited significant similarity with a sequenced plasmid from Shigella dysenteriae type I. Our findings demonstrate the mosaic nature of EPEC antibiotic resistance plasmids and highlight the need for additional sequence-based characterization of antibiotic resistance plasmids harbored by pathogenic E. coli . Copyright © 2017 American Society for Microbiology.

  2. Strain difference of cadmium-induced testicular toxicity in inbred Wistar-Imamichi and Fischer 344 rats

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hideaki; Narumi, Rika [Kumamoto University, Faculty of Education, Kumamoto (Japan); Nagano, Masaaki; Yasutake, Akira [National Institute for Minamata Disease, Biochemistry Section, Kumamoto (Japan); Waalkes, Michael P. [National Cancer Institute at the National Institute of Environmental Health Sciences, Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, Research Triangle Park, NC (United States); Imamura, Yorishige [Kumamoto University, Graduate School of Pharmaceutical Sciences, Kumamoto (Japan)

    2009-07-15

    Previously, we reported that Wistar-Imamichi (WI) rats are highly resistant to cadmium (Cd)-induced lethality and hepatotoxicity compared to Fischer 344 (F344) rats. Since the testes are one of the most sensitive organs to acute Cd toxicity, we examined possible strain-related differences in Cd-induced testicular toxicity between inbred WI and F344 rats. Rats were treated with a single dose of 0.5, 1.0 or 2.0 mg Cd/kg, as CdCl{sub 2}, sc and killed 24 h later. Cd at doses of 1.0 and 2.0 mg/kg induced severe testicular hemorrhage, as assessed by pathological and testis hemoglobin content, in F344 rats, but not WI rats. After Cd treatment (2.0 mg/kg), the testicular Cd content was significantly lower in WI rats than in the F344 rats, indicating a toxiokinetic mechanism for the observed strain difference. Thus, the remarkable resistance to Cd-induced testicular toxicity in WI rats is associated, at least in part, with lower testicular accumulation of Cd. When zinc (Zn; 10 mg/kg, sc) was administered in combination with Cd (2.0 mg/kg) to F344 rats, the Cd-induced increase in testicular hemoglobin content, indicative of hemorrhage, was significantly reduced. Similarly, the testicular Cd content was significantly decreased with Zn co-treatment compared to Cd treatment alone. Thus, it can be concluded that the testicular Cd accumulation partly competes with Zn transport systems and that these systems may play an important role in the strain-related differences in Cd-induced testicular toxicity between WI and F344 rats. (orig.)

  3. Elucidating and tuning the strain-induced non-linear behavior of polymer nanocomposites: a detailed molecular dynamics simulation study.

    Science.gov (United States)

    Shen, Jianxiang; Liu, Jun; Gao, Yangyang; Li, Xiaolin; Zhang, Liqun

    2014-07-28

    By setting up a coarse-grained model of polymer nanocomposites, we monitored the change in the elastic modulus as a function of the strain, derived from the stress-strain behavior by determining uniaxial tension and simple shear of two typical spatial distribution states (aggregation and dispersion) of nanoparticles (NPs). In both these cases, we observed that the elastic modulus decreases non-linearly with the increase of strain and reaches a low plateau at larger strains. This phenomenon is similar to the so-called "Payne effect" for elastomer nanocomposites. Particularly, the modulus of the aggregation case is more sensitive to the imposed strain. By examining the structural parameters, such as the number of neighboring NPs, coordination number of NPs, root-mean-squared average force exerted on the NPs, local strain, chain conformations (bridge, dangle, loop, interface bead and connection bead), and the total interaction energy of NP-polymer and NP-NP, we inferred that the underlying mechanism of the aggregation case is the disintegration of the NP network or clusters formed through direct contact; however, for the dispersion case, the non-linear behavior is attributed to the destruction of the NP network or clusters formed through the bridging of adsorbed polymer segments among the NPs. The former physical network is influenced by NP-NP interaction and NP volume fraction, while the latter is influenced by NP-polymer interaction and NP volume fraction. Lastly, we found that for the dispersion case, further increasing the inter-particle distance or grafting NPs with polymer chains can effectively reduce the non-linear behavior due to the decrease of the physical network density. In general, this simulation work, for the first time, establishes the correlation between the micro-structural evolution and the strain-induced non-linear behavior of polymer nanocomposites, and sheds some light on how to reduce the "Payne effect".

  4. Influence of strain-induced martensitic transformation on fatigue short crack behaviour in an austenitic stainless steel

    International Nuclear Information System (INIS)

    Baffie, N.; Stolarz, J.; Magnin, Th.

    2000-01-01

    The influence of martensitic transformation induced by cyclic straining on the mechanisms of low cycle fatigue damage in a metastable austenitic stainless steel with different grain sizes has been investigated using macroscopic measurements and microscopic observations of short crack evolutions. The amount of martensite formed during cyclic straining increases with increasing plastic strain amplitude and cumulative plastic strain but the dominant parameter is the grain size of austenite. The fine microstructure (D = 10 μm) with maximum martensite fraction of about 20% is characterised by a better fatigue resistance than the coarse one (D 40μm and only 2% of martensite) for the same plastic strain amplitude. Martensitic transformation is found to radically modify the cyclic response of the alloy and consequently the damage mechanisms. Indeed, both short crack nucleation and growth take place exclusively in the transformed regions. A mechanism of short crack propagation based on the γ→ α' transformation assisted by stress concentration at the crack tip is proposed. The indirect influence of grain boundaries in the austenite on crack propagation in the martensite is demonstrated. The better fatigue resistance of metastable alloys with fine granular structure can thus be understood. (authors)

  5. Model for field-induced reorientation strain in magnetic shape memory alloy with tensile and compressive loads

    International Nuclear Information System (INIS)

    Zhu Yuping; Dui Guansuo

    2008-01-01

    A model based on the micromechanical and the thermodynamic theory is presented for field-induced martensite reorientation in magnetic shape memory alloy (MSMA) single crystals. The influence of variants morphology and the material property to constitutive behavior is considered. The nonlinear and hysteretic strain and magnetization response of MSMA are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants under constant compressive stress and tensile stress. The predicted results have shown that increasing tensile loading reduces the required field for actuation, while increasing compressive loads result in the required magnetic field growing considerably. It is helpful to design the intelligent composite with MSMA fibers

  6. Improvement of strain Penicillium sp. EZ-ZH190 for tannase production by induced mutation.

    Science.gov (United States)

    Zakipour-Molkabadi, E; Hamidi-Esfahani, Z; Sahari, M A; Azizi, M H

    2013-11-01

    In the search for an efficient producer of tannase, Penicillium sp. EZ-ZH190 was subjected to mutagenesis using heat treatment and strain EZ-ZH290 was isolated. The maximum tannase in this mutant strain was 4.32 U/mL with an incubation period of 84 h as compared to wild strain EZ-ZH190 where the incubation period was 96 h with a maximum enzyme activity of 4.33 U/mL. Also, the Penicillium sp. EZ-ZH290 tannase had a maximum activity at 40 °C and pH 5.5. Then, the spores of strain EZ-ZH290 were subjected to γ irradiation mutagenesis and strain EZ-ZH390 was isolated. Strain EZ-ZH390 exhibited higher tannase activity (7.66 U/mL) than the parent strain EZ-ZH290. It was also found that Penicillium sp. EZ-ZH390 tannase had an optimum activity at 35 °C and a broad pH profile with an optimum at pH 5.5. The tannase pH stability of Penicillium sp. EZ-ZH390 and its maximum production of tannase followed the same trend for five generations confirming the occurrence of stable mutant. This paper is shown that γ irradiation can mutate the Penicillium sp. leading to increase the tannase production.

  7. Gamma-irradiation induced mutagenesis on some microbial strains of interest in food biotechnologies

    International Nuclear Information System (INIS)

    Ferdes, O.S.; Ferdes, M.; Dumitru, E.; Mencinicopschi, G.

    1993-01-01

    In this paper there were presented the results concerning gamma-ray effects on some microbial strains which are of interest in food biotechnologies. The irradiations are performed to a Co-60 source, under several condition, at dose rates between 0.1-2.0 kGy/h and in a dose range between 0.1-20.0 kGy. The microbial strains are of Bacillus subtilis, Aspergillus niger, Mucor pusillus and Monascus rubens from IFC collection. There were established the survival curves and the optimum irradiation doses for mutagenic effects. There were isolated, analysed and characterised some mutant strains, with better properties in obtaining food enzymes and pigments. (orig.)

  8. Pilot study on rugged fiber optic brillouin sensors for large-strain measurements to ensure the safety of transportation structures.

    Science.gov (United States)

    2012-07-01

    Brillouin-scattering Optical Time Domain Reflectometry (BOTDR) is a viable technology for simultaneous, distributed : strain and temperature measurements for miles-long transportation structures. It is a promising tool to ensure the smooth : operatio...

  9. Aeromonas caviae strain induces Th1 cytokine response in mouse intestinal tract

    Science.gov (United States)

    Aeromonas caviae has been associated with human gastrointestinal disease. Strains of this species typically lack virulence factors (VFs) such as enterotoxins and hemolysins that are produced by other human pathogens of the Aeromonas genus,. Microarray profiling of...

  10. Mechanically Strain-Induced Modification of Selenium Powders in the Amorphization Process

    International Nuclear Information System (INIS)

    Fuse, Makoto; Shirakawa, Yoshiyuki; Shimosaka, Atsuko; Hidaka, Jusuke

    2003-01-01

    For the fabrication of particles designed in the nanoscale structure, or the nanostructural modification of particles using mechanical grinding process, selenium powders ground by a planetary ball mill at various rotational speeds have been investigated. Structural analyses, such as particle size distributions, crystallite sizes, lattice strains and nearest neighbour distances were performed using X-ray diffraction, scanning electron microscopy and dynamical light scattering.By grinding powder particles became spherical composites consisting of nanocrystalline and amorphous phase, and had a distribution with the average size of 2.7 μm. Integral intensities of diffraction peaks of annealed crystal selenium decreased with increasing grinding time, and these peaks broadened due to lattice strains and reducing crystallite size during the grinding. The ground powder at 200 rpm did not have the lattice strain and showed amorphization for the present grinding periods. It indicates that the amorphization of Se by grinding accompanies the lattice strain, and the lattice strain arises from a larger energy concerning intermolecular interaction. In this process, the impact energy is spent on thermal and structural changes according to energy accumulation in macroscopic (the particle size distribution) and microscopic (the crystallite size and the lattice strain) range

  11. Mitochondrial proteomics of the acetic acid – induced programmed cell death response in a highly tolerant Zygosaccharomyces bailii – derived hybrid strain

    Directory of Open Access Journals (Sweden)

    Joana F Guerreiro

    2016-01-01

    Full Text Available Very high concentrations of acetic acid at low pH induce programmed cell death (PCD in both the experimental model Saccharomyces cerevisiae and in Zygosaccharomyces bailii, the latter being considered the most problematic acidic food spoilage yeast due to its remarkable intrinsic resistance to this food preservative. However, while the mechanisms underlying S. cerevisiae PCD induced by acetic acid have been previously examined, the corresponding molecular players remain largely unknown in Z. bailii. Also, the reason why acetic acid concentrations known to be necrotic for S. cerevisiae induce PCD with an apoptotic phenotype in Z. bailii remains to be elucidated. In this study, a 2-DE-based expression mitochondrial proteomic analysis was explored to obtain new insights into the mechanisms involved in PCD in the Z. bailii derived hybrid strain ISA1307. This allowed the quantitative assessment of expression of protein species derived from each of the parental strains, with special emphasis on the processes taking place in the mitochondria known to play a key role in acetic acid – induced PCD. A marked decrease in the content of proteins involved in mitochondrial metabolism, in particular, in respiratory metabolism (Cor1, Rip1, Lpd1, Lat1 and Pdb1, with a concomitant increase in the abundance of proteins involved in fermentation (Pdc1, Ald4, Dld3 was registered. Other differentially expressed identified proteins also suggest the involvement of the oxidative stress response, protein translation, amino acid and nucleotide metabolism, among other processes, in the PCD response. Overall, the results strengthen the emerging concept of the importance of metabolic regulation of yeast PCD.

  12. Unique Piezoelectric Properties of the Monoclinic Phase in Pb (Zr ,Ti )O3 Ceramics: Large Lattice Strain and Negligible Domain Switching

    Science.gov (United States)

    Fan, Longlong; Chen, Jun; Ren, Yang; Pan, Zhao; Zhang, Linxing; Xing, Xianran

    2016-01-01

    The origin of the excellent piezoelectric properties at the morphotropic phase boundary is generally attributed to the existence of a monoclinic phase in various piezoelectric systems. However, there exist no experimental studies that reveal the role of the monoclinic phase in the piezoelectric behavior in phase-pure ceramics. In this work, a single monoclinic phase has been identified in Pb (Zr ,Ti )O3 ceramics at room temperature by in situ high-energy synchrotron x-ray diffraction, and its response to electric field has been characterized for the first time. Unique piezoelectric properties of the monoclinic phase in terms of large intrinsic lattice strain and negligible domain switching have been observed. The extensional strain constant d33 and the transverse strain constant d31 are calculated to be 520 and -200 pm /V , respectively. These large piezoelectric coefficients are mainly due to the large intrinsic lattice strain, with very little extrinsic contribution from domain switching. The unique properties of the monoclinic phase provide new insights into the mechanisms responsible for the piezoelectric properties at the morphotropic phase boundary.

  13. Unique Piezoelectric Properties of the Monoclinic Phase in Pb(Zr,Ti)O_{3} Ceramics: Large Lattice Strain and Negligible Domain Switching.

    Science.gov (United States)

    Fan, Longlong; Chen, Jun; Ren, Yang; Pan, Zhao; Zhang, Linxing; Xing, Xianran

    2016-01-15

    The origin of the excellent piezoelectric properties at the morphotropic phase boundary is generally attributed to the existence of a monoclinic phase in various piezoelectric systems. However, there exist no experimental studies that reveal the role of the monoclinic phase in the piezoelectric behavior in phase-pure ceramics. In this work, a single monoclinic phase has been identified in Pb(Zr,Ti)O_{3} ceramics at room temperature by in situ high-energy synchrotron x-ray diffraction, and its response to electric field has been characterized for the first time. Unique piezoelectric properties of the monoclinic phase in terms of large intrinsic lattice strain and negligible domain switching have been observed. The extensional strain constant d_{33} and the transverse strain constant d_{31} are calculated to be 520 and -200  pm/V, respectively. These large piezoelectric coefficients are mainly due to the large intrinsic lattice strain, with very little extrinsic contribution from domain switching. The unique properties of the monoclinic phase provide new insights into the mechanisms responsible for the piezoelectric properties at the morphotropic phase boundary.

  14. Bending-induced electromechanical coupling and large piezoelectric response in a micromachined diaphragm

    KAUST Repository

    Wang, Zhihong

    2013-11-04

    We investigated the dependence of electromechanical coupling and the piezoelectric response of a micromachined Pb(Zr 0.52 Ti 0.48)O 3 (PZT) diaphragm on its curvature by observing the impedance spectrum and central deflection responses to a small AC voltage. The curvature of the diaphragm was controlled by applying air pressure to its back. We found that a depolarized flat diaphragm does not initially exhibit electromechanical coupling or the piezoelectric response. However, upon the application of static air pressure to the diaphragm, both electromechanical coupling and the piezoelectric response can be induced in the originally depolarized diaphragm. The piezoelectric response increases as the curvature increases and a giant piezoelectric response can be obtained from a bent diaphragm. The obtained results clearly demonstrate that a high strain gradient in a diaphragm can polarize a PZT film through a flexoelectric effect, and that the induced piezoelectric response of the diaphragm can be controlled by adjusting its curvature.

  15. 3D characterization of coal strains induced by compression, carbon dioxide sorption, and desorption at in-situ stress conditions

    Energy Technology Data Exchange (ETDEWEB)

    Pone, J. Denis N.; Halleck, Phillip M.; Mathews, Jonathan P. [Department of Energy and Mineral Engineering and The EMS Energy Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

    2010-06-01

    Sequestration of carbon dioxide in unmineable coal seams is an option to combat climate change and an opportunity to enhance coalbed methane production. Prediction of sequestration potential in coal requires characterization of porosity, permeability, sorption capacity and the magnitude of swelling due to carbon dioxide uptake or shrinkage due to methane and water loss. Unfortunately, the majority of data characterizing coal-gas systems have been obtained from powdered, unconfined coal samples. Little is known about confined coal behavior during carbon dioxide uptake and methane desorption. The present work focuses on the characterization of lithotype specific deformation, and strain behavior during CO{sub 2} uptake at simulated in-situ stress conditions. It includes the evaluation of three-dimensional strain induced by the confining stress, the sorption, and the desorption of carbon dioxide. X-ray computed tomography allowed three-dimensional characterization of the bituminous coal deformation samples under hydrostatic stress. The application of 6.9 MPa of confining stress contributes an average of - 0.34% volumetric strain. Normal strains due to confining stress were - 0.08%, - 0.15% and - 0.11% along the x, y and z axes respectively. Gas injection pressure was 3.1 MPa and the excess sorption was 0.85 mmol/g. Confined coal exposed to CO{sub 2} for 26 days displays an average volumetric expansion of 0.4%. Normal strains due to CO{sub 2} sorption were 0.11%, 0.22% and 0.11% along x, y and z axes. Drainage of the CO{sub 2} induced an average of - 0.33% volumetric shrinkage. Normal strains due to CO{sub 2} desorption were - 0.23%, - 0.08% and - 0.02% along x, y and z axes. Alternating positive and negative strain values observed along the sample length during compression, sorption and desorption respectively emphasized that both localized compression/compaction and expansion of coal will occur during CO{sub 2} sequestration. (author)

  16. Strain-induced ordered structure of titanium carbide during depositing diamond on Ti alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.J., E-mail: lixj@alum.imr.ac.cn [College of Material Science and Engineering, Key Laboratory of Advanced Structural Materials, Ministry of Education, Changchun University of Technology, Changchun, 130012 (China); He, L.L., E-mail: llhe@imr.ac.cn [Shenyang National Lab of Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Y.S. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon S7N 5A9, SK (Canada); Plasma Physics Laboratory, University of Saskatchewan, Saskatoon, SK S7N 5E2 (Canada); Yang, Q. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon S7N 5A9, SK (Canada); Hirose, A. [Plasma Physics Laboratory, University of Saskatchewan, Saskatoon, SK S7N 5E2 (Canada)

    2017-01-15

    During the deposition of diamond films on Ti alloy substrates, titanium carbide is a common precipitated phase, preferentially formed at the interfacial region. However, in this case, the precipitation of an ordered structure of titanium carbide has not been reported. In our work, a long periodic ordered structure of TiC has been observed at the deposited diamond film/Ti alloy interface by high resolution transmission electron microscopy (HRTEM). The long periodic ordered structure is identified as 6H-type. The formation mechanism is revealed by comparative studies on the different structures of TiC precipitated under different diamond deposition conditions in terms of deposition time, atmosphere and temperature. A large number of carbon vacancies in the interfacial precipitated TiC phase are verified through electron energy loss spectroscopy (EELS) quantification analysis. However, an ordered arrangement of these carbon vacancies occurs only when the interfacial stress is large enough to induce the precipitation of 6H-type TiC. The supplementary analysis by X-ray diffraction (XRD) further confirms that additional diffraction peaks presented in the XRD patterns are corresponding to the precipitation of 6H-type TiC. - Highlights: •Different structures of TiC are observed during deposited diamond on Ti alloy. •One is common NaCl structure, the other is periodic structure. •The periodic structure is identified as 6H-type by HRTEM. •Carbon vacancies are verified to always exist in the TiC phase. •The precipitation of 6H-type TiC is mainly affected by interfacial stress.

  17. Strain-induced ordered structure of titanium carbide during depositing diamond on Ti alloy substrate

    International Nuclear Information System (INIS)

    Li, X.J.; He, L.L.; Li, Y.S.; Yang, Q.; Hirose, A.

    2017-01-01

    During the deposition of diamond films on Ti alloy substrates, titanium carbide is a common precipitated phase, preferentially formed at the interfacial region. However, in this case, the precipitation of an ordered structure of titanium carbide has not been reported. In our work, a long periodic ordered structure of TiC has been observed at the deposited diamond film/Ti alloy interface by high resolution transmission electron microscopy (HRTEM). The long periodic ordered structure is identified as 6H-type. The formation mechanism is revealed by comparative studies on the different structures of TiC precipitated under different diamond deposition conditions in terms of deposition time, atmosphere and temperature. A large number of carbon vacancies in the interfacial precipitated TiC phase are verified through electron energy loss spectroscopy (EELS) quantification analysis. However, an ordered arrangement of these carbon vacancies occurs only when the interfacial stress is large enough to induce the precipitation of 6H-type TiC. The supplementary analysis by X-ray diffraction (XRD) further confirms that additional diffraction peaks presented in the XRD patterns are corresponding to the precipitation of 6H-type TiC. - Highlights: •Different structures of TiC are observed during deposited diamond on Ti alloy. •One is common NaCl structure, the other is periodic structure. •The periodic structure is identified as 6H-type by HRTEM. •Carbon vacancies are verified to always exist in the TiC phase. •The precipitation of 6H-type TiC is mainly affected by interfacial stress.

  18. Strain-induced grain growth of cryomilled nanocrystalline Al in trimodal composites during forging

    International Nuclear Information System (INIS)

    Yao, B.; Simkin, B.; Majumdar, B.; Smith, C.; Bergh, M. van den; Cho, K.; Sohn, Y.H.

    2012-01-01

    Highlights: ► Grain growth of cryomilled nanocrystalline aluminum during hot forging. ► Use of hollow cone dark field imaging technique in TEM for grain size measurement. ► Grain growth model of strain, strain rate and temperature for forging optimization. - Abstract: Grain growth of nanocrystalline aluminum ( nc Al) in trimodal Al metal-matrix-composites (MMCs) during hot forging was investigated. The nc Al phase formed through cryomilling of inert gas-atomized powders in liquid nitrogen has an average grain size down to 21 nm, exhibits excellent thermal stability. However, substantial grain growth of nc Al up to 63 nm was observed when the Al MMCs were thermo-mechanically processed even at relatively low temperatures. Grain growth of the cryomilled nc Al phase in trimodal Al MMCs after hot forging was documented with respect to temperature ranging from 175 °C to 287 °C, true strain ranging from 0.4 to 1.35 and strain rate ranging from 0.1 to 0.5 s −1 . Hollow cone dark field imaging technique was employed to provide statistically confident measurements of nc Al grain size that ranged from 21 to 63 nm. An increase in forging temperature and an increase in true strain were correlated with an increase in grain size of nc Al. Results were correlated to devise a phenomenological grain growth model for forging that takes strain, strain rate and temperature into consideration. Activation energy for the grain growth during thermo-mechanical hot-forging was determined to be 35 kJ/mol, approximately a quarter of activation energy for bulk diffusion of Al and a half of activation energy for static recrystallization.

  19. On the lag time between internal strain and basement involved thrust induced exhumation: The case of the Colombian Eastern Cordillera

    Science.gov (United States)

    Mora, Andrès; Blanco, Vladimir; Naranjo, Julian; Sanchez, Nelson; Ketcham, Richard A.; Rubiano, Jorge; Stockli, Daniel F.; Quintero, Isaid; Nemčok, Michal; Horton, Brian K.; Davila, Hamblet

    2013-07-01

    Thrust sheets accumulate internal strain before they start moving along discrete fault planes. However, there are no previous studies evaluating the time difference between initiation of strain and fault displacement. In this paper we use observations from the Eastern Cordillera of Colombia to evaluate this interval. We utilize multiple thermochronometers and paleothermometers to refine the timing of deformation. Based on these new data we build time-temperature path estimates that together with geometric outcrop-based structural analysis and fluid inclusions allow us to assign relative timing to features associated with strain, such as cleavage, veins and certain types of fractures, and compare that with the timing of thrusting. We find that cleavage was only formed close to maximum paleotemperatures, almost coeval with the onset of thrust-induced denudation by the Late Oligocene. The corresponding structural level of fold-related veins suggest that they were formed later but still when the country rocks were at temperatures higher than 160 °C, mostly during the Early Miocene and still coexisted with the latest stages of cleavage formation. Our data show that the main period of strain hardening was short (probably a few million years) and occurred before first-order basement thrusting was dominant, but was associated with second-order folding.

  20. Strain induced effects on the transport properties of metamorphic InAlAs/InGaAs quantum wells

    International Nuclear Information System (INIS)

    Capotondi, F.; Biasiol, G.; Ercolani, D.; Grillo, V.; Carlino, E.; Romanato, F.; Sorba, L.

    2005-01-01

    The relationship between structural and low-temperature transport properties is explored for In x Al 1 - x As/In x Ga 1 - x As metamorphic quantum wells with x > 0.7 grown on GaAs by molecular beam epitaxy. Different step-graded buffer layers are used to gradually adapt the in-plane lattice parameter from the GaAs towards the InGaAs value. We show that using buffer layers with a suitable maximum In content the residual compressive strain in the quantum well region can be strongly reduced. Samples with virtually no residual strain in the quantum well region show a low-temperature electron mobility up to 29 m 2 /V s while for samples with higher residual compressive strain the low-temperature mobility is reduced. Furthermore, for samples with buffers inducing a tensile strain in the quantum well region, deep grooves are observed on the surface, and in correspondence we notice a strong deterioration of the low-temperature transport properties

  1. Direct production of feruloyl oligosaccharides and hemicellulase inducement and distribution in a newly isolated Aureobasidium pullulans strain.

    Science.gov (United States)

    Yu, Xiao-hong; Gu, Zhen-xin

    2014-02-01

    Studies were carried out to screen and identify strains that are able to directly produce ferulic oligosaccharides (FOs) from wheat bran (WB). The inducement and distribution of hemicellulases from strain 2012, which was identified as a non-melanin secreting strain of Aureobasidium pullulans (A. pullulans), were also determined. In a 60 g/L WB solution, A. pullulans could produce 545 nmol/L FOs, 64.12 IU/mL xylanase and 0.14 IU/mL ferulic acid esterase (FAE). A. pullulans was cultivated in media with WB, glucose, xylose, sucrose, lactose or xylan as the carbon source, and hemicellulases were mainly induced by xylan and WB and inhibited by glucose and sucrose. Xylanase and FAE were mainly present in the culture filtrate, xylosidase in the hyphal filaments and arabinofuranosidase was a membrane-bound enzyme. The yield of FOs was positively correlated to the hemicellulases activity, and significantly positively (P < 0.05) correlated to the xylanase activity (r = 0.992).

  2. X-Ray-Induced Damage to the Submandibular Salivary Glands in Mice: An Analysis of Strain-Specific Responses

    Science.gov (United States)

    Kamiya, Mana; Kawase, Tomoyuki; Hayama, Kazuhide; Tsuchimochi, Makoto; Okuda, Kazuhiro; Yoshie, Hiromasa

    2015-01-01

    Abstract Radiation therapy for head and neck cancers often causes xerostomia (dry mouth) by acutely damaging the salivary glands through the induction of severe acute inflammation. By contrast, the mechanism underlying the X-ray-induced delayed salivary dysfunction is unknown and has attracted increasing attention. To identify and develop a mouse model that distinguishes the delayed from the acute effects, we examined three different mouse strains (C57BL/6, ICR, and ICR-nu/nu) that showed distinct T-cell activities to comparatively analyze their responses to X-ray irradiation. Three strains were irradiated with X-rays (25 Gy), and functional changes of the submandibular glands were examined by determining pilocarpine-induced saliva secretion. Structural changes were evaluated using histopathological and immunohistochemical examinations of CD3, cleaved poly (ADP-ribose) polymerase (PARP), and Bcl-xL. In C57BL/6 mice, the X-ray irradiation induced acute inflammation accompanied by severe inflammatory cell infiltration at 4 days postirradiation, causing substantial destruction and significant dysfunction at 2 weeks. Fibrotic repair was observed at 16 weeks. In ICR-nu/nu mice, the inflammation and organ destruction were much milder than in the other mice strains, but increased apoptotic cells and a significant reduction in salivary secretion were observed at 4 and 8 weeks and beyond, respectively. These results suggest that in C57BL/6 mice, X-ray-induced functional and structural damage to the salivary glands is caused mainly by acute inflammation. By contrast, although neither acute inflammation nor organ destruction was observed in ICR-nu/nu mice, apoptotic cell death preceded the dysfunction in salivary secretion in the later phase. These data suggest that the X-ray-irradiated ICR-nu/nu mouse may be a useful animal model for developing more specific therapeutic methods for the delayed dysfunction of salivary glands. PMID:26309806

  3. Strain-induced recovery of electronic anisotropy in 90°-twisted bilayer phosphorene

    Science.gov (United States)

    Xie, Jiafeng; Luo, Qiangjun; Jia, Lei; Zhang, Z. Y.; Shi, H. G.; Yang, D. Z.; Si, M. S.

    2018-01-01

    It is well known that anisotropy determines the preferred transport direction of carriers. To manipulate the anisotropy is an exciting topic in two-dimensional materials, where the carriers are confined within individual layers. In this work, it is found that uniaxial strain can tune the electronic anisotropy of the 90°-twisted bilayer phosphorene. In this unique bilayer structure, the zigzag direction of one layer corresponds to the armchair one of the other layer and vice versa. Owing to this complementary structure, the directional (zigzag or armchair) deformation response to strain of one layer is opposite to that of the other layer, where the in-plane positive Poisson's ratio plays a key role. As a result, the doubly degenerate highest valence bands split, followed by a recovery of anisotropy. More interestingly, such an anisotropy, namely, the ratio of the effective mass along the Γ \\text- X direction to that along the Γ \\text- Y direction, reaches as high as 6 under a small strain of 1%, and keeps nearly unchanged up to a strain of 3%. In addition, high anisotropy only holds for hole carriers as the conduction band is insensitive to strain. These findings should shed new light on the design of semiconducting devices, where the hole acts as the transport carrier.

  4. Temperature Driven Topological Switch in 1T'-MoTe2 and Strain Induced Nematicity in NaFeAs

    Science.gov (United States)

    Berger, Ayelet Denise Notis

    Quasiparticle interference (QPI) is a powerful technique within Scanning Tunneling Microscopy (STM) that is used to probe the electronic bandstructure of materials. This thesis presents two examples using QPI to measure the bandstructure in materials with exotic electronic states that can be tuned via outside parameters (temperature and strain). In Part I of the thesis, we discuss the temperature dependence of Fermi Arcs in 1T'-MoTe 2, and then in Part II, the strain dependent nematic state in NaFeAs. The recent discovery of Weyl semimetals has introduced a new family of materials with topologically protected electronic properties and potential applications due to their anomalous transport effects. Even more useful is a Weyl semimetal that can be turned "on" and "off," switching between a topological and trivial state. One possible material is MoTe2, which undergoes a phase transition at 240K. This thesis consists of experiments using Scanning Tunneling Microscopy (STM) and Spectroscopy (STS) at different temperatures to visualize changes in the electronic bandstructure of MoTe2 across the topological phase transition. We show that a signature of topologically protected Fermi Arcs is present at low temperatures but disappears at room temperature, in the trivial phase. We include an in-depth discussion of how to account for thermal effects when comparing these two types of measurements. In Part II, we discuss strain induced nematicity in NaFeAs, an iron pnictide. Nematic fluctuations and spin correlations play an important role in the phase diagram of the iron pnictides, a family of unconventional superconductors. Illuminating the mechanism behind this symmetry breaking is key to understanding the superconducting state. Previous work has shown that nematicity in the iron pnictides responds strongly to applied strain [1, 2]. In this thesis, I present results from a new experimental technique, elasto-scanning tunneling microscopy (E-STM), which combines in situ strain

  5. An Inducible Operon Is Involved in Inulin Utilization in Lactobacillus plantarum Strains, as Revealed by Comparative Proteogenomics and Metabolic Profiling.

    Science.gov (United States)

    Buntin, Nirunya; Hongpattarakere, Tipparat; Ritari, Jarmo; Douillard, François P; Paulin, Lars; Boeren, Sjef; Shetty, Sudarshan A; de Vos, Willem M

    2017-01-15

    The draft genomes of Lactobacillus plantarum strains isolated from Asian fermented foods, infant feces, and shrimp intestines were sequenced and compared to those of well-studied strains. Among 28 strains of L. plantarum, variations in the genomic features involved in ecological adaptation were elucidated. The genome sizes ranged from approximately 3.1 to 3.5 Mb, of which about 2,932 to 3,345 protein-coding sequences (CDS) were predicted. The food-derived isolates contained a higher number of carbohydrate metabolism-associated genes than those from infant feces. This observation correlated to their phenotypic carbohydrate metabolic profile, indicating their ability to metabolize the largest range of sugars. Surprisingly, two strains (P14 and P76) isolated from fermented fish utilized inulin. β-Fructosidase, the inulin-degrading enzyme, was detected in the supernatants and cell wall extracts of both strains. No activity was observed in the cytoplasmic fraction, indicating that this key enzyme was either membrane-bound or extracellularly secreted. From genomic mining analysis, a predicted inulin operon of fosRABCDXE, which encodes β-fructosidase and many fructose transporting proteins, was found within the genomes of strains P14 and P76. Moreover, pts1BCA genes, encoding sucrose-specific IIBCA components involved in sucrose transport, were also identified. The proteomic analysis revealed the mechanism and functional characteristic of the fosRABCDXE operon involved in the inulin utilization of L. plantarum The expression levels of the fos operon and pst genes were upregulated at mid-log phase. FosE and the LPXTG-motif cell wall anchored β-fructosidase were induced to a high abundance when inulin was present as a carbon source. Inulin is a long-chain carbohydrate that may act as a prebiotic, which provides many health benefits to the host by selectively stimulating the growth and activity of beneficial bacteria in the colon. While certain lactobacilli can catabolize

  6. Islanding and strain-induced shifts in the infrared absorption peaks of cubic boron nitride thin films

    International Nuclear Information System (INIS)

    Fahy, S.; Taylor, C.A. II and; Clarke, R.

    1997-01-01

    Experimental and theoretical investigations of the infrared-active, polarization-dependent phonon frequencies of cubic boron nitride films have been performed in light of recent claims that large frequency shifts during initial nucleation are the result of strain caused by highly nonequilibrium growth conditions. We show that the formation of small, separate grains of cubic boron nitride during the initial growth leads to a frequency shift in the infrared-active transverse-optic mode, polarized normal to the substrate, which is opposite in sign and twice the magnitude of the shift for modes polarized parallel to the substrate. In contrast, film strain causes a frequency shift in the mode polarized normal to the substrate, which is much smaller in magnitude than the frequency shift for modes polarized parallel to the substrate. Normal and off-normal incidence absorption measurements, performed at different stages of nucleation and growth, show that large frequency shifts in the transverse-optic-phonon modes during the initial stage of growth are not compatible with the expected effects of strain, but are in large part due to nucleation of small isolated cubic BN grains which coalesce to form a uniform layer. Numerical results from a simple model of island nucleation and growth are in good agreement with experimental results. copyright 1997 The American Physical Society

  7. Flexible Polydimethylsiloxane Foams Decorated with Multiwalled Carbon Nanotubes Enable Unprecedented Detection of Ultralow Strain and Pressure Coupled with a Large Working Range.

    Science.gov (United States)

    Iglio, Rossella; Mariani, Stefano; Robbiano, Valentina; Strambini, Lucanos; Barillaro, Giuseppe

    2018-04-25

    Low-cost piezoresistive strain/pressure sensors with large working range, at the same time able to reliably detect ultralow strain (≤0.1%) and pressure (≤1 Pa), are one of the challenges that have still to be overcome for flexible piezoresistive materials toward personalized health-monitoring applications. In this work, we report on unprecedented, simultaneous detection of ultrasmall strain (0.1%, i.e., 10 μm displacement over 10 mm) and subtle pressure (20 Pa, i.e., a force of only 2 mN over an area of 1 cm 2 ) in compression mode, coupled with a large working range (i.e., up to 60% for strain-6 mm in displacement-and 50 kPa for pressure) using piezoresistive, flexible three-dimensional (3D) macroporous polydimethylsiloxane (pPDMS) foams decorated with pristine multiwalled carbon nanotubes (CNTs). pPDMS/CNT foams with pore size up to 500 μm (i.e., twice the size of those of commonly used foams, at least) and porosity of 77%, decorated with a nanostructured surface network of CNTs at densities ranging from 7.5 to 37 mg/cm 3 are prepared using a low-cost and scalable process, through replica molding of sacrificial sugar templates and subsequent drop-casting of CNT ink. A thorough characterization shows that piezoresistive properties of the foams can be finely tuned by controlling the CNT density and reach an optimum at a CNT density of 25 mg/cm 3 , for which a maximum change of the material resistivity (e.g., ρ 0 /ρ 50 = 4 at 50% strain) is achieved under compression. Further static and dynamic characterization of the pPDMS/CNT foams with 25 mg/cm 3 of CNTs highlights that detection limits for strain and pressure are 0.03% (3 μm displacement over 10 mm) and 6 Pa (0.6 mN over an area of 1 cm 2 ), respectively; moreover, good stability and limited hysteresis are apparent by cycling the foams with 255 compression-release cycles over the strain range of 0-60%, at different strain rates up to 10 mm/min. Our results on piezoresistive, flexible pPDMS/CNT foams

  8. Strain-induced band engineering in monolayer stanene on Sb(111)

    Science.gov (United States)

    Gou, Jian; Kong, Longjuan; Li, Hui; Zhong, Qing; Li, Wenbin; Cheng, Peng; Chen, Lan; Wu, Kehui

    2017-10-01

    The two-dimensional (2D) allotrope of tin with low buckled honeycomb structure named stanene is proposed to be an ideal 2D topological insulator with a nontrivial gap larger than 0.1 eV. Theoretical works also pointed out the topological property of stanene amenability to strain tuning. In this paper we report the successful realization of high quality, monolayer stanene film as well as monolayer stanene nanoribbons on Sb(111) surface by molecular-beam epitaxy, providing an ideal platform to the study of stanene. More importantly, we observed a continuous evolution of the electronic bands of stanene across the nanoribbon, related to the strain field gradient in stanene. Our work experimentally confirmed that strain is an effective method for band engineering in stanene, which is important for fundamental research and application of stanene.

  9. Strain-induced formation of fourfold symmetric SiGe quantum dot molecules.

    Science.gov (United States)

    Zinovyev, V A; Dvurechenskii, A V; Kuchinskaya, P A; Armbrister, V A

    2013-12-27

    The strain field distribution at the surface of a multilayer structure with disklike SiGe nanomounds formed by heteroepitaxy is exploited to arrange the symmetric quantum dot molecules typically consisting of four elongated quantum dots ordered along the [010] and [100] directions. The morphological transition from fourfold quantum dot molecules to continuous fortresslike quantum rings with an increasing amount of deposited Ge is revealed. We examine key mechanisms underlying the formation of lateral quantum dot molecules by using scanning tunneling microscopy and numerical calculations of the strain energy distribution on the top of disklike SiGe nanomounds. Experimental data are well described by a simple thermodynamic model based on the accurate evaluation of the strain dependent part of the surface chemical potential. The spatial arrangement of quantum dots inside molecules is attributed to the effect of elastic property anisotropy.

  10. Migration and strains induced by different designs of force-closed stems for THA.

    Science.gov (United States)

    Griza, Sandro; Gomes, Luiz Sérgio Marcelino; Cervieri, André; Strohaecker, Telmo Roberto

    2015-01-01

    Subtle differences in stem design can result in different mechanical responses of the total hip arthroplasty. Tests measuring migration of the stem relative to the femur, as well as the strains in the cement mantle and on the femur can detect different mechanical behavior between stems. In this article, conical, double and triple tapered stems were implanted in composite femurs and subjected to static and cyclic loads. Stems differed mainly on taper angle, calcar radius and proximal stiffness. Stem migration and strains on the femur and in the cement mantle were achieved. Significant differences (p mechanical tests were able to detect significant differences in the behavior of these resembling stems. Stem proximal stiffness and the calcar radius of the stem influence its rotational stability and the strain transmission to the femur.

  11. Strain induced tunable wavelength filters based on flexible polymer waveguide Bragg reflector.

    Science.gov (United States)

    Kim, Kyung-Jo; Seo, Jun-Kyu; Oh, Min-Cheol

    2008-02-04

    A tunable wavelength filter is demonstrated by imposing a strain on a polymeric Bragg reflection waveguide fabricated on a flexible substrate. The highly elastic property of flexible polymer device enables much wider tuning than the silica fiber. To produce a uniform grating pattern on a flexible plastic substrate, a post lift-off process along with an absorbing layer is incorporated. The flexible Bragg reflector shows narrow bandwidth, which is convincing the uniformity of the grating structure fabricated on plastic film. By stretching the flexible polymer device, the Bragg reflection wavelength is tuned continuously up to 45 nm for the maximum strain of 31,690 muepsilon, which is determined by the elastic expansion limit of waveguide polymer. From the linear wavelength shift proportional to the strain, the photoelastic coefficient of the ZPU polymer is found.

  12. The Role of Hydrogen-Enhanced Strain-Induced Lattice Defects on Hydrogen Embrittlement Susceptibility of X80 Pipeline Steel

    Science.gov (United States)

    Hattori, M.; Suzuki, H.; Seko, Y.; Takai, K.

    2017-08-01

    Studies to date have not completely determined the factors influencing hydrogen embrittlement of ferrite/bainite X80 pipeline steel. Hydrogen embrittlement susceptibility was evaluated based on fracture strain in tensile testing. We conducted a thermal desorption analysis to measure the amount of tracer hydrogen corresponding to that of lattice defects. Hydrogen embrittlement susceptibility and the amount of tracer hydrogen significantly increased with decreasing crosshead speed. Additionally, a significant increase in the formation of hydrogen-enhanced strain-induced lattice defects was observed immediately before the final fracture. In contrast to hydrogen-free specimens, the fracture surface of the hydrogen-charged specimens exhibited shallower dimples without nuclei, such as secondary phase particles. These findings indicate that the presence of hydrogen enhanced the formation of lattice defects, particularly just prior to the occurrence of final fracture. This in turn enhanced the formation of shallower dimples, thereby potentially causing premature fracture of X80 pipeline steel at lower crosshead speeds.

  13. Uniaxial Drawing of Graphene-PVA Nanocomposites: Improvement in Mechanical Characteristics via Strain-Induced Exfoliation of Graphene

    Science.gov (United States)

    Jan, Rahim; Habib, Amir; Akram, Muhammad Aftab; Zia, Tanveer-ul-Haq; Khan, Ahmad Nawaz

    2016-08-01

    Polyvinyl alcohol (PVA)-stabilized graphene nanosheets (GNS) of lateral dimension ( L) ~1 μm are obtained via liquid phase exfoliation technique to prepare its composites in the PVA matrix. These composites show low levels of reinforcements due to poor alignment of GNS within the matrix as predicted by the modified Halpin-Tsai model. Drawing these composites up to 200 % strain, a significant improvement in mechanical properties is observed. Maximum values for Young's modulus and strength are ~×4 and ~×2 higher respectively than that of neat PVA. Moreover, the rate of increase of the modulus with GNS volume fraction is up to 700 GPa, higher than the values predicted using the Halpin-Tsai theory. However, alignment along with strain-induced de-aggregation of GNS within composites accounts well for the obtained results as confirmed by X-ray diffraction (XRD) characterization.

  14. Extensional Strain Hardening Induced by π -π Interactions in Barely Entangled Polymer Chains: The Curious Case of Poly(4-vinylbiphenyl)

    Science.gov (United States)

    López-Barrón, Carlos R.; Zhou, Huaxing

    2017-12-01

    Aromatic π -π interactions between phenyl groups of adjacent chains in poly(4-vinylbiphenyl) (PVBP) have profound effects on the dynamics of this polymer. We report two unexpected nonlinear viscoelastic responses of PVBP when subjected to uniaxial flow. One is the unprecedented observation of extensional strain hardening (SH) in a barely entangled polymer melt. An even more intriguing finding is that SH of lightly (or even barely) entangled melts occurs at strain rates one order of magnitude below the coil-stretch transition predicted by Rouse theory (ɛ˙ H=0.5 /τR ).We postulate that this behavior is due to a molecular rearrangement mechanism (supported by x-ray diffraction measurements) that involves flow-induced π -π stacking of the phenyl groups, which results in an enhancement of the friction coefficient between polymer chains.

  15. Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

    KAUST Repository

    Cheng, Yingchun

    2012-10-01

    The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon–heptagon pairs (from hexagon–hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

  16. Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

    KAUST Repository

    Cheng, Yingchun; Schwingenschlö gl, Udo; Zhu, Zhiyong

    2012-01-01

    The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon–heptagon pairs (from hexagon–hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

  17. Systemic resistance and lipoxygenase-related defence response induced in tomato by Pseudomonas putida strain BTP1

    Directory of Open Access Journals (Sweden)

    Dommes Jacques

    2008-11-01

    Full Text Available Abstract Background Previous studies showed the ability of Pseudomonas putida strain BTP1 to promote induced systemic resistance (ISR in different host plants. Since ISR is long-lasting and not conducive for development of resistance of the targeted pathogen, this phenomenon can take part of disease control strategies. However, in spite of the numerous examples of ISR induced by PGPR in plants, only a few biochemical studies have associated the protective effect with specific host metabolic changes. Results In this study, we showed the protective effect of this bacterium in tomato against Botrytis cinerea. Following treatment by P. putida BTP1, analyses of acid-hydrolyzed leaf extracts showed an accumulation of antifungal material after pathogen infection. The fungitoxic compounds thus mainly accumulate as conjugates from which active aglycones may be liberated through the activity of hydrolytic enzymes. These results suggest that strain BTP1 can elicit systemic phytoalexin accumulation in tomato as one defence mechanism. On another hand, we have shown that key enzymes of the lipoxygenase pathway are stimulated in plants treated with the bacteria as compared with control plants. Interestingly, this stimulation is observed only after pathogen challenge in agreement with the priming concept almost invariably associated with the ISR phenomenon. Conclusion Through the demonstration of phytoalexin accumulation and LOX pathway stimulation in tomato, this work provides new insights into the diversity of defence mechanisms that are inducible by non-pathogenic bacteria in the context of ISR.

  18. Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions.

    Science.gov (United States)

    Costa, Suelen B; Campos, Ana Carolina C; Pereira, Ana Claudia M; de Mattos-Guaraldi, Ana Luiza; Júnior, Raphael Hirata; Rosa, Ana Cláudia P; Asad, Lídia M B O

    2014-09-01

    During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the

  19. A triply cloned strain of xylella fastidiosa multiplies and induces symptoms of citrus variegated chlorosis in sweet orange

    Science.gov (United States)

    Li; Zreik; Fernandes; Miranda; Teixeira; Ayres; Garnier; Bov

    1999-08-01

    Xylella fastidiosa isolate 8.1.b obtained from a sweet orange tree affected by citrus variegated chlorosis in the state of Sao Paulo, Brazil, and shown in 1993 to be the causal agent of the disease, was cloned by repeated culture in liquid and on solid PW medium, yielding triply cloned strain 9a5c. The eighth and the 16th passages of strain 9a5c were mechanically inoculated into sweet orange plants. Presence of X. fastidiosa in sweet orange leaves of shoots having grown after inoculation (first-flush shoots) was detected by DAS-ELISA and PCR. Thirty-eight days after inoculation, 70% of the 20 inoculated plants tested positive, and all plants gave strong positive reactions 90 days after inoculation. Symptoms first appeared after 3 months and were conspicuous after 5 months. X. fastidiosa was reisolated from sweet orange leaves, 44 days after inoculation. These results indicate that X. fastidiosa strain 9a5c, derived from pathogenic isolate 8.1.b by triply cloning, is also pathogenic. Strain 9a5c is now used for the X. fastidiosa genome sequencing project undertaken on a large scale in Brazil.http://link. springer-ny.com/link/service/journals/00284/bibs/39n2p106.html

  20. Genetic affinities within a large global collection of pathogenic Leptospira: implications for strain identification and molecular epidemiology.

    Directory of Open Access Journals (Sweden)

    Kishore Nalam

    Full Text Available Leptospirosis is an important zoonosis with widespread human health implications. The non-availability of accurate identification methods for the individualization of different Leptospira for outbreak investigations poses bountiful problems in the disease control arena. We harnessed fluorescent amplified fragment length polymorphism analysis (FAFLP for Leptospira and investigated its utility in establishing genetic relationships among 271 isolates in the context of species level assignments of our global collection of isolates and strains obtained from a diverse array of hosts. In addition, this method was compared to an in-house multilocus sequence typing (MLST method based on polymorphisms in three housekeeping genes, the rrs locus and two envelope proteins. Phylogenetic relationships were deduced based on bifurcating Neighbor-joining trees as well as median joining network analyses integrating both the FAFLP data and MLST based haplotypes. The phylogenetic relationships were also reproduced through Bayesian analysis of the multilocus sequence polymorphisms. We found FAFLP to be an important method for outbreak investigation and for clustering of isolates based on their geographical descent rather than by genome species types. The FAFLP method was, however, not able to convey much taxonomical utility sufficient to replace the highly tedious serotyping procedures in vogue. MLST, on the other hand, was found to be highly robust and efficient in identifying ancestral relationships and segregating the outbreak associated strains or otherwise according to their genome species status and, therefore, could unambiguously be applied for investigating phylogenetics of Leptospira in the context of taxonomy as well as gene flow. For instance, MLST was more efficient, as compared to FAFLP method, in clustering strains from the Andaman island of India, with their counterparts from mainland India and Sri Lanka, implying that such strains share genetic

  1. Thermomechanically induced residual strains in Al/SiCp metal-matrix composites

    DEFF Research Database (Denmark)

    Lorentzen, T.; Clarke, A.P.

    1998-01-01

    Residual lattice strains in the aluminium and SiC phases of F3S.20S extruded A359 20% SiC metal-matrix composite were measured by using neutron diffi action at room and elevated temperatures to monitor the effects of in situ uniaxial plastic deformations. The results are interpreted with referenc...

  2. Thermal Annealing induced relaxation of compressive strain in porous GaN structures

    KAUST Repository

    Ben Slimane, Ahmed; Najar, Adel; Ng, Tien Khee; Ooi, Boon S.

    2012-01-01

    The effect of annealing on strain relaxation in porous GaN fabricated using electroless chemical etching is presented. The Raman shift of 1 cm-1 in phonon frequency of annealed porous GaN with respect to as-grown GaN corresponds to a relaxation

  3. Numerical and experimental study of moisture-induced stress and strain field developments in timber logs

    DEFF Research Database (Denmark)

    Larsen, Finn; Ormarsson, Sigurdur

    2013-01-01

    shrinkage and the inhomogeneity of the material. To obtain a better understanding of how stresses develop during climatic variations, the field histories of stresses (and strains) in cross sections in their entirety need to be studied. The present paper reports on experiments and numerical simulations...

  4. Hydrogen-induced delayed cracking: 1. Strain energy effects on hydrogen solubility

    International Nuclear Information System (INIS)

    Puls, M.P.

    1978-08-01

    Based on Li, Oriani and Darken's derivation of the chemical potential of a solute in a stressed solid and Eshelby's method for obtaining the strain energy of solids containing coherent inhomogeneous inclusions, we have carried out a detailed theoretical analysis of the factors governing hydrogen solubility in stressed and unstressed zirconium and its alloys. Specifically, the analysis demonstrates the strong influence hydride self-stresses may have on the terminal solid solubility of hydrogen in zirconium. The self-energy arises due to the misfit strains between matrix and precipitate. We have calculated the total molal self-strain energy of some commonly observed δ and γ-hydride shapes and orientations. The magnitude of this energy is substantial. Thus for γ-hydride plates lying on basal planes, it is 4912 J/mol, while for γ-hydride needles with the needle axis parallel to the directions of the α-zirconium matrix, it is 2662 J/mol. This self-strain energy causes a shift in the terminal solid solubility. For example, at 77 o C, assuming fully constrained basal plane δ-hydride plates, the terminal solid solubility is increased 5.4 times over the stress-free case. We have also calculated the effect of external stress on the terminal solid solubility. This is governed by the interaction energy arising from the interaction of the applied stresses with the precipitate's misfit strain components. The interaction energy has been calculated for δ and γ-hydride plates and needles, taking full account of the anisotropy of the misfit. The interaction energy is negative for tensile applied stresses and, as a result of the anisotropic misfit, is texture-dependent. Its magnitude is small for most applied stresses but can achieve values of the order of the self-strain energy in the plastic zone of a plane-strain crack. We have also carried out a careful analysis of the solubility data of Kearns and Erickson and Hardie. This analysis is based partly on the theoretical

  5. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Mark, J. Abraham Hudson, E-mail: a.john.peter@gmail.com; Peter, A. John, E-mail: a.john.peter@gmail.com [Dept. of Physics, SSM Institute of Engineering and Technology, Dindigul-624002 (India)

    2014-04-24

    Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  6. Tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge

    Energy Technology Data Exchange (ETDEWEB)

    Inaoka, Takeshi, E-mail: inaoka@phys.u-ryukyu.ac.jp; Furukawa, Takuro; Toma, Ryo; Yanagisawa, Susumu [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213 (Japan)

    2015-09-14

    By means of a hybrid density-functional method, we investigate the tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge. We consider [001], [111], and [110] uniaxial tensility and (001), (111), and (110) biaxial tensility. Under the condition of no normal stress, we determine both normal compression and internal strain, namely, relative displacement of two atoms in the primitive unit cell, by minimizing the total energy. We identify those strain types which can induce the band-gap transition, and evaluate the critical strain coefficient where the gap transition occurs. Either normal compression or internal strain operates unfavorably to induce the gap transition, which raises the critical strain coefficient or even blocks the transition. We also examine how each type of tensile strain decreases the band-gap energy, depending on its orientation. Our analysis clearly shows that synergistic operation of strain orientation and band anisotropy has a great influence on the gap transition and the gap energy.

  7. Cafestol Inhibits Cyclic-Strain-Induced Interleukin-8, Intercellular Adhesion Molecule-1, and Monocyte Chemoattractant Protein-1 Production in Vascular Endothelial Cells

    Science.gov (United States)

    Hao, Wen-Rui; Sung, Li-Chin; Chen, Chun-Chao; Chen, Jin-Jer

    2018-01-01

    Moderate coffee consumption is inversely associated with cardiovascular disease mortality; however, mechanisms underlying this causal effect remain unclear. Cafestol, a diterpene found in coffee, has various properties, including an anti-inflammatory property. This study investigated the effect of cafestol on cyclic-strain-induced inflammatory molecule secretion in vascular endothelial cells. Cells were cultured under static or cyclic strain conditions, and the secretion of inflammatory molecules was determined using enzyme-linked immunosorbent assay. The effects of cafestol on mitogen-activated protein kinases (MAPK), heme oxygenase-1 (HO-1), and sirtuin 1 (Sirt1) signaling pathways were examined using Western blotting and specific inhibitors. Cafestol attenuated cyclic-strain-stimulated intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 8 secretion. Cafestol inhibited the cyclic-strain-induced phosphorylation of extracellular signal-regulated kinase and p38 MAPK. By contrast, cafestol upregulated cyclic-strain-induced HO-1 and Sirt1 expression. The addition of zinc protoporphyrin IX, sirtinol, or Sirt1 silencing (transfected with Sirt1 siRNA) significantly attenuated cafestol-mediated modulatory effects on cyclic-strain-stimulated ICAM-1, MCP-1, and IL-8 secretion. This is the first study to report that cafestol inhibited cyclic-strain-induced inflammatory molecule secretion, possibly through the activation of HO-1 and Sirt1 in endothelial cells. The results provide valuable insights into molecular pathways that may contribute to the effects of cafestol. PMID:29854096

  8. Isolation and characterization of large spectrum and multiple bacteriocin-producing Enterococcus faecium strain from raw bovine milk.

    Science.gov (United States)

    Gaaloul, N; ben Braiek, O; Hani, K; Volski, A; Chikindas, M L; Ghrairi, T

    2015-02-01

    To assess the antimicrobial properties of lactic acid bacteria from Tunisian raw bovine milk. A bacteriocin-producing Enterococcus faecium strain was isolated from raw cow milk with activity against Gram-positive and Gram-negative bacteria. Antimicrobial substances produced by this strain were sensitive to proteolytic enzymes and were thermostable and resistant to a broad range of pH (2-10). Mode of action of antimicrobial substances was determined as bactericidal. Maximum activity was reached at the end of the exponential growth phase when checked against Listeria ivanovii BUG 496 (2366.62 AU ml(-1)). However, maximum antimicrobial activity against Pseudomonas aeruginosa 28753 was recorded at the beginning of the exponential growth phase. Enterococcus faecium GGN7 was characterized as free from virulence factors and was susceptible to tested antibiotics. PCR analysis of the micro-organism's genome revealed the presence of genes coding for enterocins A and B. Mass spectrometry analysis of RP-HPLC active fractions showed molecular masses corresponding to enterocins A (4835.77 Da) and B (5471.56 Da), and a peptide with a molecular mass of 3215.5 Da active only against Gram-negative indicator strains. The latter was unique in the databases. Enterococcus faecium GGN7 produces three bacteriocins with different inhibitory spectra. Based on its antimicrobial properties and safety, Ent. faecium GGN7 is potentially useful for food biopreservation. The results suggest the bacteriocins from GGN7 strain could be useful for food biopreservation. © 2014 The Society for Applied Microbiology.

  9. Genomic Variability of Mycobacterium tuberculosis Strains of the Euro-American Lineage Based on Large Sequence Deletions and 15-Locus MIRU-VNTR Polymorphism

    Science.gov (United States)

    Rindi, Laura; Medici, Chiara; Bimbi, Nicola; Buzzigoli, Andrea; Lari, Nicoletta; Garzelli, Carlo

    2014-01-01

    A sample of 260 Mycobacterium tuberculosis strains assigned to the Euro-American family was studied to identify phylogenetically informative genomic regions of difference (RD). Mutually exclusive deletions of regions RD115, RD122, RD174, RD182, RD183, RD193, RD219, RD726 and RD761 were found in 202 strains; the RDRio deletion was detected exclusively among the RD174-deleted strains. Although certain deletions were found more frequently in certain spoligotype families (i.e., deletion RD115 in T and LAM, RD174 in LAM, RD182 in Haarlem, RD219 in T and RD726 in the “Cameroon” family), the RD-defined sublineages did not specifically match with spoligotype-defined families, thus arguing against the use of spoligotyping for establishing exact phylogenetic relationships between strains. Notably, when tested for katG463/gyrA95 polymorphism, all the RD-defined sublineages belonged to Principal Genotypic Group (PGG) 2, except sublineage RD219 exclusively belonging to PGG3; the 58 Euro-American strains with no deletion were of either PGG2 or 3. A representative sample of 197 isolates was then analyzed by standard 15-locus MIRU-VNTR typing, a suitable approach to independently assess genetic relationships among the strains. Analysis of the MIRU-VNTR typing results by using a minimum spanning tree (MST) and a classical dendrogram showed groupings that were largely concordant with those obtained by RD-based analysis. Isolates of a given RD profile show, in addition to closely related MIRU-VNTR profiles, related spoligotype profiles that can serve as a basis for better spoligotype-based classification. PMID:25197794

  10. Enhanced saturated fatty acids accumulation in cultures of newly-isolated strains of Schizochytrium sp. and Thraustochytriidae sp. for large-scale biodiesel production.

    Science.gov (United States)

    Wang, Qiuzhen; Sen, Biswarup; Liu, Xianhua; He, Yaodong; Xie, Yunxuan; Wang, Guangyi

    2018-08-01

    Heterotrophic marine protists (Thraustochytrids) have received increasingly global attention as a renewable, sustainable and alternative source of biodiesel because of their high ability of saturated fatty acids (SFAs) accumulation. Yet, the influence of extrinsic factors (nutrients and environmental conditions) on thraustochytrid culture and optimal conditions for high SFAs production are poorly described. In the present study, two different thraustochytrid strains, Schizochytrium sp. PKU#Mn4 and Thraustochytriidae sp. PKU#Mn16 were studied for their growth and SFAs production profiles under various conditions (carbon, nitrogen, temperature, pH, KH 2 PO 4 , salinity, and agitation speed). Of the culture conditions, substrates (C and N) source and conc., temperature, and agitation speed significantly influenced the cell growth and SFAs production of both strains. Although both the strains were capable of growth and SFAs production in the broad range of culture conditions, their physiological responses to KH 2 PO 4 , pH, and salinity were dissimilar. Under their optimal batch culture conditions, peak SFAs productions of 3.3g/L and 2.2g/L with 62% and 49% SFAs contents (relative to total fatty acids) were achieved, respectively. The results of 5-L fed-batch fermentation under optimal conditions showed a nearly 4.5-fold increase in SFAs production (i.e., 7.5g/L) by both strains compared to unoptimized conditions. Of the two strains, the quality of biodiesel produced from the fatty acids of PKU#Mn4 met the biodiesel standard defined by ASTM6751. This study, to the knowledge of the authors, is the first comprehensive report of optimal fermentation conditions demonstrating enhanced SFAs production by strains belonging to two different thraustochytrid genera and provides the basis for large-scale biodiesel production. Copyright © 2018. Published by Elsevier B.V.

  11. A large-scale perspective on stress-induced alterations in resting-state networks

    Science.gov (United States)

    Maron-Katz, Adi; Vaisvaser, Sharon; Lin, Tamar; Hendler, Talma; Shamir, Ron

    2016-02-01

    Stress is known to induce large-scale neural modulations. However, its neural effect once the stressor is removed and how it relates to subjective experience are not fully understood. Here we used a statistically sound data-driven approach to investigate alterations in large-scale resting-state functional connectivity (rsFC) induced by acute social stress. We compared rsfMRI profiles of 57 healthy male subjects before and after stress induction. Using a parcellation-based univariate statistical analysis, we identified a large-scale rsFC change, involving 490 parcel-pairs. Aiming to characterize this change, we employed statistical enrichment analysis, identifying anatomic structures that were significantly interconnected by these pairs. This analysis revealed strengthening of thalamo-cortical connectivity and weakening of cross-hemispheral parieto-temporal connectivity. These alterations were further found to be associated with change in subjective stress reports. Integrating report-based information on stress sustainment 20 minutes post induction, revealed a single significant rsFC change between the right amygdala and the precuneus, which inversely correlated with the level of subjective recovery. Our study demonstrates the value of enrichment analysis for exploring large-scale network reorganization patterns, and provides new insight on stress-induced neural modulations and their relation to subjective experience.

  12. Two-dimensional silica: Structural, mechanical properties, and strain-induced band gap tuning

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Enlai; Xie, Bo [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); Xu, Zhiping, E-mail: xuzp@tsinghua.edu.cn [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2016-01-07

    Two-dimensional silica is of rising interests not only for its practical applications as insulating layers in nanoelectronics, but also as a model material to understand crystals and glasses. In this study, we examine structural and electronic properties of hexagonal and haeckelite phases of silica bilayers by performing first-principles calculations. We find that the corner-sharing SiO{sub 4} tetrahedrons in these two phases are locally similar. The robustness and resilience of these tetrahedrons under mechanical perturbation allow effective strain engineering of the electronic structures with band gaps covering a very wide range, from of that for insulators, to wide-, and even narrow-gap semiconductors. These findings suggest that the flexible 2D silica holds great promises in developing nanoelectronic devices with strain-tunable performance, and lay the ground for the understanding of crystalline and vitreous phases in 2D, where bilayer silica provides an ideal test-bed.

  13. MODELING OF STRAIN-INDUCED PRECIPITATION KINETICS IN Nb MICROALLOYED STEELS

    Institute of Scientific and Technical Information of China (English)

    X.G. Zhou; Z.Y. Liu; D. Wu; Z.Li; C.M. Li

    2006-01-01

    On the basis of the thermodynamic calculation of precipitation and considering the effect of strain on the precipitation behavior and chemical composition (Si and Mn), the kinetics of precipitation from austenite has been investigated for different temperatures and strains. Nucleation theory and the solubility product of niobium, carbon, and nitrogen in austenite have been used to derive equations for the start time of precipitation as a function of temperature and composition. The value of n in Avrami equation was determined using the available experimental data from the published reports, which indicated that n is a constant independent of temperature and the end time of precipitation is a function of n and the start time of precipitation. The values of the start time and end time of precipitation predicted by the new model are compared with the experimental values and a good agreement was obtained between both.

  14. Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

    Science.gov (United States)

    Habermeier, H.-U.

    2008-10-01

    Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

  15. Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

    International Nuclear Information System (INIS)

    Habermeier, H-U

    2008-01-01

    Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

  16. Strain-induced tunable negative differential resistance in triangle graphene spirals

    Science.gov (United States)

    Tan, Jie; Zhang, Xiaoming; Liu, Wenguan; He, Xiujie; Zhao, Mingwen

    2018-05-01

    Using non-equilibrium Green’s function formalism combined with density functional theory calculations, we investigate the significant changes in electronic and transport properties of triangle graphene spirals (TGSs) in response to external strain. Tunable negative differential resistance (NDR) behavior is predicted. The NDR bias region, NDR width, and peak-to-valley ratio can be well tuned by external strain. Further analysis shows that these peculiar properties can be attributed to the dispersion widths of the p z orbitals. Moreover, the conductance of TGSs is very sensitive to the applied stress, which is promising for applications in nanosensor devices. Our findings reveal a novel approach to produce tunable electronic devices based on graphene spirals.

  17. Bifidobacterium adolescentis Exerts Strain-Specific Effects on Constipation Induced by Loperamide in BALB/c Mice

    Directory of Open Access Journals (Sweden)

    Linlin Wang

    2017-02-01

    Full Text Available Constipation is one of the most common gastrointestinal complaints worldwide. This study was performed to determine whether Bifidobacterium adolescentis exerts inter-strain differences in alleviating constipation induced by loperamide in BALB/c mice and to analyze the main reasons for these differences. BALB/c mice underwent gavage with B. adolescentis (CCFM 626, 667, and 669 once per day for 17 days. The primary outcome measures included related constipation indicators, and the secondary outcome measures were the basic biological characteristics of the strains, the concentration changes of short-chain fatty acids in feces, and the changes in the fecal flora. B. adolescentis CCFM 669 and 667 relieved constipation symptoms by adhering to intestinal epithelial cells, growing quickly in vitro and increasing the concentrations of propionic and butyric acids. The effect of B. adolescentis on the gut microbiota in mice with constipation was investigated via 16S rRNA metagenomic analysis. The results revealed that the relative abundance of Lactobacillus increased and the amount of Clostridium decreased in the B. adolescentis CCFM 669 and 667 treatment groups. In conclusion, B. adolescentis exhibits strain-specific effects in the alleviation of constipation, mostly due to the strains’ growth rates, adhesive capacity and effects on the gut microbiome and microenvironment.

  18. Effect of lattice mismatch-induced strains on coupled diffusive and displacive phase transformations

    OpenAIRE

    Bouville, Mathieu; Ahluwalia, Rajeev

    2006-01-01

    Materials which can undergo slow diffusive transformations as well as fast displacive transformations are studied using the phase-field method. The model captures the essential features of the time-temperature-transformation (TTT) diagrams, continuous cooling transformation (CCT) diagrams, and microstructure formation of these alloys. In some materials systems there can exist an intrinsic volume change associated with these transformations. We show that these coherency strains can stabilize m...

  19. Effect of Mouse Strain in a Model of Chemical-induced Respiratory Allergy

    OpenAIRE

    Nishino, Risako; Fukuyama, Tomoki; Watanabe, Yuko; Kurosawa, Yoshimi; Ueda, Hideo; Kosaka, Tadashi

    2014-01-01

    The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical–related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical–related respiratory allergens by using a long-term sensitization–challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences ...

  20. Electric field-induced valley degeneracy lifting in uniaxial strained graphene: evidence from magnetophonon resonance

    OpenAIRE

    Assili, Mohamed; Haddad, Sonia; Kang, Woun

    2015-01-01

    A double peak structure in the magneto-phonon resonance (MPR) spectrum of uniaxial strained graphene, under crossed electric and magnetic fields, is predicted. We focus on the $\\Gamma$ point optical phonon modes coupled to the inter-Landau level transitions $0 \\leftrightarrows \\pm 1$ where MPR is expected to be more pronounced at high magnetic field. We derive the frequency shifts and the broadenings of the longitudinal (LO) and transverse (TO) optical phonon modes taking into account the eff...

  1. Hyphal-like extension and pseudohyphal formation in industrial strains of yeasts induced by isoamyl alcohol

    Directory of Open Access Journals (Sweden)

    Ceccato-Antonini Sandra Regina

    2002-01-01

    Full Text Available Yeasts can produce pseudohyphae and hyphal-like extensions under certain growth conditions like isoamyl alcohol (IAA induction, a chief constituent of fusel oil, which is a subproduct from the ethanolic fermentation. The morphology switch from yeast to a filamentous form can be troublesome to the process. In this work it was studied the influence of fusel alcohols, nitrogen sources (ammonium sulphate and leucine and glifosate (a chemical maturator for sugar cane added to a complex medium on some industrial strains of yeasts isolated from the fermentative process. Two industrial strains showed transition to hyphal-like extensions or pseudohyphae (clusters of cells upon addition of IAA from 0.3 to 0.9% /v. The alterations were reversible when the yeasts were reinoculated in YEPD without IAA. Although pseudohyphae are a result of nitrogen-limited medium, we observed them as a result of IAA addition. No influence of the nitrogen source or isopropilic alcohol or glifosate was detected for any strain studied in the concentrations used.

  2. Strain-induced topological magnon phase transitions: applications to kagome-lattice ferromagnets

    Science.gov (United States)

    Owerre, S. A.

    2018-06-01

    A common feature of topological insulators is that they are characterized by topologically invariant quantity such as the Chern number and the index. This quantity distinguishes a nontrivial topological system from a trivial one. A topological phase transition may occur when there are two topologically distinct phases, and it is usually defined by a gap closing point where the topologically invariant quantity is ill-defined. In this paper, we show that the magnon bands in the strained (distorted) kagome-lattice ferromagnets realize an example of a topological magnon phase transition in the realistic parameter regime of the system. When spin–orbit coupling (SOC) is neglected (i.e. no Dzyaloshinskii–Moriya interaction), we show that all three magnon branches are dispersive with no flat band, and there exists a critical point where tilted Dirac and semi-Dirac point coexist in the magnon spectra. The critical point separates two gapless magnon phases as opposed to the usual phase transition. Upon the inclusion of SOC, we realize a topological magnon phase transition point at the critical strain , where D and J denote the perturbative SOC and the Heisenberg spin exchange interaction respectively. It separates two distinct topological magnon phases with different Chern numbers for and for . The associated anomalous thermal Hall conductivity develops an abrupt change at , due to the divergence of the Berry curvature in momentum space. The proposed topological magnon phase transition is experimentally feasible by applying external perturbations such as uniaxial strain or pressure.

  3. Radiation-induced pulmonary endothelial dysfunction and hydroxyproline accumulation in four strains of mice

    International Nuclear Information System (INIS)

    Ward, W.F.; Sharplin, J.; Franko, A.J.; Hinz, J.M.

    1989-01-01

    C57BL mice exposed to 14 Gy of whole-thorax irradiation develop significant histologic lung fibrosis within 52 weeks, whereas CBA and C3H mice do not exhibit substantial fibrosis during this time. The purpose of the present study was to determine whether this strain-dependent difference in radiation histopathology is associated with genetic differences in pulmonary endothelial metabolic activity or in endothelial radioresponsiveness. C57BL/6J, C57BL/10J, CBA/J, and C3H/HeJ mice were sacrificed 12 weeks after exposure to 0 or 14 Gy of 300-kV X rays to the whole thorax. Lung angiotensin converting enzyme (ACE) activity and plasminogen activator (PLA) activity were measured as indices of pulmonary endothelial function; and lung hydroxyproline (HP) content served as an index of pulmonary fibrosis. Lung ACE and PLA activities in sham-irradiated C57BL/6J and CB57BL/10J mice were only half as high as those in sham-irradiated CBA/J and C3H/HeJ mice. Exposure to 14 Gy of X rays produced a slight but nonsignificant reduction in lung ACE and PLA activity in the C57BL strains, and a significant reduction in the CBA/J and C3H/HeJ mice. Even after 14 Gy, however, lung ACE and PLA activities in CBA/J and C3H/HeJ mice were higher than those in sham-irradiated C57BL/6J and C57BL/10J mice. Lung HP content in all four strains increased significantly after irradiation, but this increase was accompanied by an increase in lung wet weight. As a result, HP concentration (per milligram wet weight) remained constant or increased slightly in both C57BL strains and actually decreased in the CBA/J and C3H/HeJ mice. These data demonstrate significant genetic differences in both intrinsic pulmonary endothelial enzyme activity and endothelial radioresponsiveness among the four strains of mice

  4. Pseudo-variables method to calculate HMA relaxation modulus through low-temperature induced stress and strain

    International Nuclear Information System (INIS)

    Canestrari, Francesco; Stimilli, Arianna; Bahia, Hussain U.; Virgili, Amedeo

    2015-01-01

    Highlights: • Proposal of a new method to analyze low-temperature cracking of bituminous mixtures. • Reliability of the relaxation modulus master curve modeling through Prony series. • Suitability of the pseudo-variables approach for a close form solution. - Abstract: Thermal cracking is a critical failure mode for asphalt pavements. Relaxation modulus is the major viscoelastic property that controls the development of thermally induced tensile stresses. Therefore, accurate determination of the relaxation modulus is fundamental for designing long lasting pavements. This paper proposes a reliable analytical solution for constructing the relaxation modulus master curve by measuring stress and strain thermally induced in asphalt mixtures. The solution, based on Boltzmann’s Superposition Principle and pseudo-variables concepts, accounts for time and temperature dependency of bituminous materials modulus, avoiding complex integral transformations. The applicability of the solution is demonstrated by testing a reference mixture using the Asphalt Thermal Cracking Analyzer (ATCA) device. By applying thermal loadings on restrained and unrestrained asphalt beams, ATCA allows the determination of several parameters, but is still unable to provide reliable estimations of relaxation properties. Without them the measurements from ATCA cannot be used in modeling of pavement behavior. Thus, the proposed solution successfully integrates ATCA experimental data. The same methodology can be applied to all test methods that concurrently measure stress and strain. The statistical parameters used to evaluate the goodness of fit show optimum correlation between theoretical and experimental results, demonstrating the accuracy of this mathematical approach

  5. Theory of the electronic structure and carrier dynamics of strain-induced (Ga, In)As quantum dots

    International Nuclear Information System (INIS)

    Boxberg, Fredrik; Tulkki, Jukka

    2007-01-01

    Strain-induced quantum dots (SIQD) confine electrons and holes to a lateral potential minimum within a near-surface quantum well (QW). The potential minimum is located in the QW below a nanometre-sized stressor crystal grown on top of the QW. SIQD exhibit well-resolved and prominently atomic-like optical spectra, making them ideal for experimental and theoretical studies of mesoscopic phenomena in semiconductor nanocrystals. In this report we review the theory of strain-induced confinement, electronic structure, photonics and carrier relaxation dynamics in SIQD. The theoretical results are compared with available experimental data. Electronic structure calculations are mainly performed using the multiband envelope function approach. Many-body effects are discussed using a direct diagonalization method, albeit, for the sake of computational feasibility, within a two-band model. The QD carrier dynamics are discussed in terms of a master equation model, which accounts for the details of the electronic structure as well as the leading photon, phonon and Coulomb interaction processes. We also discuss the quantum confined Stark effect, the Zeeman splitting and the formation of Landau levels in external fields. Finally, we review a recent theory of the cooling of radiative QD excitons by THz radiation. In particular we discuss the resonance charge transfer of holes between piezoelectric trap states and the deformation potential minima. The agreement between the theory and experiment is fair throughout, but calls for further investigations

  6. A large-strain, fast-response, and easy-to-manufacture electrothermal actuator based on laser-reduced graphene oxide

    Science.gov (United States)

    Zhang, Tian-Yu; Wang, Qian; Deng, Ning-Qin; Zhao, Hai-Ming; Wang, Dan-Yang; Yang, Zhen; Liu, Ying; Yang, Yi; Ren, Tian-Ling

    2017-09-01

    In this paper, we have developed a high-performance graphene electrothermal actuator (ETA). The fabrication method is easy, fast, environmentally friendly, and suitable for preparing both large-size and miniature graphene ETAs. When applied with the driving voltage of 65 V, the graphene ETA achieves a large bending angle of 270° with a fast response of 8 s and the recovery process costs 19 s. The large bending deformation is reversible and can be precisely controlled by the driving voltage. A simple robotic hand prepared by using a single graphene ETA can hold the object, which is more than ten times the weight of itself. By virtue of its large-strain, fast response, and easy-to-manufacture, we believe that the graphene ETA has tremendous potential in extensive applications involving biomimetic robotics, artificial muscles, switches, and microsensors in both macroscopic and microscopic fields.

  7. Microbial induced corrosion (MIC) on DHP copper by Desulfovibrio desulfuricans and Bacillus megaterium strains in media simulating heater waters

    International Nuclear Information System (INIS)

    Zumelzu, E.; Cabezas, C.; Schoebitz, R.; Ugarte, R.; Rodriguez, E.D.; Rios, J.

    2003-01-01

    The complexity and diversity of microbial populations in water heating systems of steam generators make it necessary to study the magnitude of the metabolic activity of bacteria and biofilm development that may lead to degradation of metal components through microbial induced corrosion (MIC). Electrolytes simulating the conditions found in heater water networks were used to induce biofilm formation on DHP copper coupons by Desulfovibrio desulfuricans DSMZ and Bacillus megaterium C10, a commercial strain and an isolate from these waters, respectively. In order to enhance their action, industrial waters enriched with the minimum nutrient content such as sodium lactate and sodium sulphite for the DSMZ strain and glucose, proteose peptone and starch for the C10 strain were employed. Biofilm formation was studied under controlled temperature, time, shaking, pH and concentrations of the media used in this study. Then, the samples were electrochemically tested in an artificial solution of sea water as control medium, based on the hypothesis that the action of an aggressive biofilm/electrolyte medium generates damaged and non-damaged areas on the metal surface, and assuming that the sea water trial can detect the latter. Hence, a higher anodic current was associated with a lower degradation of the metal surface by the action of one of the media under study. All these trials were performed along with bacterial count, scanning electron microscopy (SEM) and atomic absorption spectroscopy (AAS). Furthermore, it was possible to identify under which conditions MIC on DHP copper occurred and complex mechanisms from retention of cations to diffusion processes at the biofilm/tested media interface level were proposed. Surface corrosion by MIC took place on DHP copper; therefore, greater control on the treatment of industrial waters is highly desirable. (author)

  8. Controlling residual dipolar couplings in high-resolution NMR of proteins by strain induced alignment in a gel

    International Nuclear Information System (INIS)

    Ishii, Yoshitaka; Markus, Michelle A.; Tycko, Robert

    2001-01-01

    Water-soluble biological macromolecules can be weakly aligned by dissolution in a strained, hydrated gel such as cross-linked polyacrylamide, an effect termed 'strain-induced alignment in a gel' (SAG). SAG induces nonzero nuclear magnetic dipole-dipole couplings that can be measured in high-resolution NMR spectra and used as structural constraints. The dependence of experimental 15 N- 1 H dipolar couplings extracted from two-dimensional heteronuclear single quantum coherence (HSQC) spectra on several properties of compressed polyacrylamide, including the extent of compression, the polyacrylamide concentration, and the cross-link density, is reported for the B1 immunoglobulin binding domain of streptococcal protein G (protein G/B1, 57 residues). It is shown that the magnitude of macromolecular alignment can be widely varied by adjusting these properties, although the orientation and asymmetry of the alignment tensor are not affected significantly. The dependence of the 15 N relaxation times T 1 and T 2 of protein G/B1 on polyacrylamide concentration are also reported. In addition, the results of 15 N relaxation and HSQC experiments on the RNA binding domain of prokaryotic protein S4 from Bacillus stearothermophilus (S4 Δ41, residues 43-200) in a compressed polyacrylamide gel are presented. These results demonstrate the applicability of SAG to proteins of higher molecular weight and greater complexity. A modified in-phase/anti-phase (IPAP) HSQC technique is described that suppresses natural-abundance 15 N background signals from amide groups in polyacrylamide, resulting in cleaner HSQC spectra in SAG experiments. The mechanism of protein alignment in strained polyacrylamide gels is contrasted with that in liquid crystalline media

  9. [Diffuse large B-cell lymphoma complicated with drug-induced vasculitis during administration of pegfilgrastim].

    Science.gov (United States)

    Ito, Yuta; Noda, Kentaro; Aiba, Keisuke; Yano, Shingo; Fujii, Tsunehiro

    A 59-year-old female with diffuse large B-cell lymphoma was treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) regimen. In addition, we administered pegfilgrastim for treating chemotherapy-induced febrile neutropenia. She complained of fever and neck and chest pain a few days after pegfilgrastim administration during the third and fourth courses of R-CHOP. Radiological imaging revealed an inflammation of large vessels, which led to the diagnosis of drug-associated vasculitis. We confirmed that vasculitis observed in this case was caused by pegfilgrastim administration because similar symptoms appeared with both injections of pegfilgrastim.

  10. Investigation of induced radioactivity in the CERN Large Electron Positron collider for its decommissioning

    CERN Document Server

    Silari, Marco

    2004-01-01

    The future installation of the Large Hadron Collider in the tunnel formerly housing the Large Electron Positron collider (LEP) required the dismantling of the latter after 11-year operation. As required by the French legislation, an extensive theoretical study was conducted before decommissioning to establish the possible activation paths both in the accelerator and in the four experiments (L3, ALEPH, OPAL and DELPHI) installed around the ring. The aim was to define which areas may contain activated material and which ones would be completely free of activation. The four major sources of activation in LEP, i.e., distributed and localized beam losses, synchrotron radiation and the super-conducting RF cavities, were investigated. Conversion coefficients from unit lost beam power to induced specific activity were established for a number of materials. A similar study was conducted for the four experiments, evaluating the four potential sources of induced radioactivity, namely e**+e **- annihilation events, two-p...

  11. High mobility AlGaN/GaN heterostructures grown on Si substrates using a large lattice-mismatch induced stress control technology

    International Nuclear Information System (INIS)

    Cheng, Jianpeng; Yang, Xuelin; Sang, Ling; Guo, Lei; Hu, Anqi; Xu, Fujun; Tang, Ning; Wang, Xinqiang; Shen, Bo

    2015-01-01

    A large lattice-mismatch induced stress control technology with a low Al content AlGaN layer has been used to grow high quality GaN layers on 4-in. Si substrates. The use of this technology allows for high mobility AlGaN/GaN heterostructures with electron mobility of 2040 cm 2 /(V·s) at sheet charge density of 8.4 × 10 12  cm −2 . Strain relaxation and dislocation evolution mechanisms have been investigated. It is demonstrated that the large lattice mismatch between the low Al content AlGaN layer and AlN buffer layer could effectively promote the edge dislocation inclination with relatively large bend angles and therefore significantly reduce the dislocation density in the GaN epilayer. Our results show a great potential for fabrication of low-cost and high performance GaN-on-Si power devices

  12. Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hai-ming; Liu, Shao-bin, E-mail: lsb@nuaa.edu.cn; Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun [Key Laboratory of Radar Imaging and Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Shen-yun [Research Center of Applied Electromagnetics, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2015-03-16

    In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

  13. Effects of Fermented Milk with Mixed Strains as a Probiotic on the Inhibition of Loperamide-Induced Constipation.

    Science.gov (United States)

    Kim, Byoung-Kook; Choi, In Suk; Kim, Jihee; Han, Sung Hee; Suh, Hyung Joo; Hwang, Jae-Kwan

    2017-01-01

    To investigate the effects of a single bacterium and a mixture of bacteria as probiotics in loperamide-treated animal models, loperamide (3 mg/kg) was administered to SD rats to induce constipation. The individual lactic acid bacterial doses, Enterococcus faecium (EF), Lactobacillus acidophilus (LA), Streptococcus thermophilus (ST), Bifidobacterium bifidum (BB), Bifidobacterium lactis (BL), Pediococcus pentosaceus (PP), and a mixture of the bacteria were orally administered to loperamide-induced constipated rats at a concentration of 10 8 CFU/kg for 14 days. The weights and water contents of their stools were found to be significantly higher in PP, CKDB (mixture of 5 strains except PP), and CKDBP (CKDB+PP) groups than in the normal (constipation not induced) and the control (constipation-induced) groups ( p mucus secretion were significantly improved in all probiotic-treated-groups, as compared to that in the control group, and the CKDBP group was found to be the most effective according to immunohistochemistry (IHC) staining and total short chain fatty acid content analysis ( p <0.05). Lastly, PP, CKDB, and CKDBP showed relatively higher Lactobacillus sp. ratios of 61.94%, 60.31% and 51.94%, respectively, compared to the other groups, based on metagenomic analysis.

  14. Large Eddy Simulation of turbulence induced secondary flows in stationary and rotating straight square ducts

    Science.gov (United States)

    Sudjai, W.; Juntasaro, V.; Juttijudata, V.

    2018-01-01

    The accuracy of predicting turbulence induced secondary flows is crucially important in many industrial applications such as turbine blade internal cooling passages in a gas turbine and fuel rod bundles in a nuclear reactor. A straight square duct is popularly used to reveal the characteristic of turbulence induced secondary flows which consists of two counter rotating vortices distributed in each corner of the duct. For a rotating duct, the flow can be divided into the pressure side and the suction side. The turbulence induced secondary flows are converted to the Coriolis force driven two large circulations with a pair of additional vortices on the pressure wall due to the rotational effect. In this paper, the Large Eddy Simulation (LES) of turbulence induced secondary flows in a straight square duct is performed using the ANSYS FLUENT CFD software. A dynamic kinetic energy subgrid-scale model is used to describe the three-dimensional incompressible turbulent flows in the stationary and the rotating straight square ducts. The Reynolds number based on the friction velocity and the hydraulic diameter is 300 with the various rotation numbers for the rotating cases. The flow is assumed fully developed by imposing the constant pressure gradient in the streamwise direction. For the rotating cases, the rotational axis is placed perpendicular to the streamwise direction. The simulation results on the secondary flows and the turbulent statistics are found to be in good agreement with the available Direct Numerical Simulation (DNS) data. Finally, the details of the Coriolis effects are discussed.

  15. A mouse strain less responsive to dioxin-induced prostaglandin E2 synthesis is resistant to the onset of neonatal hydronephrosis.

    Science.gov (United States)

    Aida-Yasuoka, Keiko; Yoshioka, Wataru; Kawaguchi, Tatsuya; Ohsako, Seiichiroh; Tohyama, Chiharu

    2014-10-01

    Dioxin is a ubiquitous environmental pollutant that induces toxicity when bound to the aryl hydrocarbon receptor (AhR). Significant differences in susceptibility of mouse strains to dioxin toxicity are largely accounted for by the dissociation constant of binding to dioxins of AhR subtypes encoded by different alleles. We showed that cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1), components of a prostanoid synthesis pathway, play essential roles in the onset of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced hydronephrosis of neonatal mice. Although C57BL/6J and BALB/cA mice harbor AhR receptors highly responsive to TCDD, they were found by chance to differ significantly in the incidence of TCDD-induced hydronephrosis. Therefore, the goal of the present study was to determine the molecular basis of this difference in susceptibility to TCDD toxicity. For this purpose, we administered C57BL/6J and BALB/cA dams' TCDD at an oral dose of 15 or 80 μg/kg on postnatal day (PND) 1 to expose pups to TCDD via lactation, and the pups' kidneys were collected on PND 7. The incidence of hydronephrosis in C57BL/6J pups (64%) was greater than in BALB/cA pups (0%, p hydronephrosis in these mouse strains paralleled the levels of renal mPGES-1 mRNA and early growth response 1 (Egr-1) that modulates mPGES-1 gene expression, as well as PGE2 concentrations in urine. Although these mouse strains possess AhR alleles tightly bound to TCDD, their difference in incidence and severity of hydronephrosis can be explained, in part, by differences in the expression of mPGES-1 and Egr-1. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  16. Effect of mouse strain in a model of chemical-induced respiratory allergy.

    Science.gov (United States)

    Nishino, Risako; Fukuyama, Tomoki; Watanabe, Yuko; Kurosawa, Yoshimi; Ueda, Hideo; Kosaka, Tadashi

    2014-01-01

    The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical-related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical-related respiratory allergens by using a long-term sensitization-challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences in respiratory allergic reactions to the well-known chemical respiratory allergen glutaraldehyde (GA). According to our protocol, BALB/c, NC/Nga, C3H/HeN, C57BL/6N, and CBA/J mice were sensitized dermally with GA for 3 weeks and then challenged with intratracheal or inhaled GA at 2 weeks after the last sensitization. The day after the final challenge, all mice were euthanized, and total serum IgE levels were assayed. In addition, immunocyte counts, cytokine production, and chemokine levels in the hilar lymph nodes (LNs) and bronchoalveolar lavage fluids (BALF) were also assessed. In conclusion, BALB/c and NC/Nga mice demonstrated markedly increased IgE reactions. Inflammatory cell counts in BALF were increased in the treated groups of all strains, especially BALB/c, NC/Nga, and CBA/J strains. Cytokine levels in LNs were increased in all treated groups except for C3H/HeN and were particularly high in BALB/c and NC/Nga mice. According to our results, we suggest that BALB/c and NC/Nga are highly susceptible to respiratory allergic responses and therefore are good candidates for use in our model for detecting environmental chemical respiratory allergens.

  17. Laser-induced novel patterns: As smart strain actuators for new-age dental implant surfaces

    International Nuclear Information System (INIS)

    Çelen, Serap; Özden, Hüseyin

    2012-01-01

    Highlights: ► It is time for that paradigm shift and for an exploration of novel surfaces. ► We developed novel 3D smart surfaces as strain actuators by nanosecond laser pulse energies. ► We analyzed these smart surface morphologies using FEM. ► We estimated their internal stiffness values which play a great role on stress shielding effect. ► We gave the optimum operation parameters. - Abstract: Surface morphologies of titanium implants are of crucial importance for long-term mechanical adaptation for following implantation. One major problem is the stress shielding effect which originates from the mismatch of the bone and the implant elasticity. It is time for a paradigm shift and for an exploration of novel smart surfaces to prevent this problem. Several surface treatment methods have traditionally been used to modify the surface morphology of titanium dental implants. The laser micro-machining can be considered as a unique and promising, non-contact, no media, contamination free, and flexible treatment method for modifying surface properties of materials in the biomedical industry. The aim of the present study is two folds; to develop novel 3D smart surfaces which can be acted as strain actuators by nanosecond laser pulse energies and irradiation strategies. And analyze these smart surface morphologies using finite element methods in order to estimate their internal stiffness values which play a great role on stress shielding effect. Novel 3D smart strain actuators were prepared using an ytterbium fiber laser (λ = 1060 nm) with 200–250 ns pulse durations on commercial pure titanium dental implant material specimen surfaces and optimum operation parameters were suggested.

  18. Laser-induced novel patterns: As smart strain actuators for new-age dental implant surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Celen, Serap, E-mail: serap.celen@ege.edu.tr [Ege University, Faculty of Engineering, Mechanical Engineering Department, Izmir, 35100 (Turkey); Oezden, Hueseyin [Ege University, Faculty of Engineering, Mechanical Engineering Department, Izmir, 35100 (Turkey)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer It is time for that paradigm shift and for an exploration of novel surfaces. Black-Right-Pointing-Pointer We developed novel 3D smart surfaces as strain actuators by nanosecond laser pulse energies. Black-Right-Pointing-Pointer We analyzed these smart surface morphologies using FEM. Black-Right-Pointing-Pointer We estimated their internal stiffness values which play a great role on stress shielding effect. Black-Right-Pointing-Pointer We gave the optimum operation parameters. - Abstract: Surface morphologies of titanium implants are of crucial importance for long-term mechanical adaptation for following implantation. One major problem is the stress shielding effect which originates from the mismatch of the bone and the implant elasticity. It is time for a paradigm shift and for an exploration of novel smart surfaces to prevent this problem. Several surface treatment methods have traditionally been used to modify the surface morphology of titanium dental implants. The laser micro-machining can be considered as a unique and promising, non-contact, no media, contamination free, and flexible treatment method for modifying surface properties of materials in the biomedical industry. The aim of the present study is two folds; to develop novel 3D smart surfaces which can be acted as strain actuators by nanosecond laser pulse energies and irradiation strategies. And analyze these smart surface morphologies using finite element methods in order to estimate their internal stiffness values which play a great role on stress shielding effect. Novel 3D smart strain actuators were prepared using an ytterbium fiber laser ({lambda} = 1060 nm) with 200-250 ns pulse durations on commercial pure titanium dental implant material specimen surfaces and optimum operation parameters were suggested.

  19. Extracellular matrix metabolism disorder induced by mechanical strain on human parametrial ligament fibroblasts.

    Science.gov (United States)

    Min, Jie; Li, Bingshu; Liu, Cheng; Guo, Wenjun; Hong, Shasha; Tang, Jianming; Hong, Li

    2017-05-01

    Pelvic organ prolapse (POP) is a global health problem that may seriously impact the quality of life of the sufferer. The present study aimed to investigate the potential mechanisms underlying alterations in extracellular matrix (ECM) metabolism in the pathogenesis of POP, by investigating the expression of ECM components in human parametrial ligament fibroblasts (hPLFs) subject to various mechanical strain loads. Fibroblasts derived from parametrial ligaments were cultured from patients with POP and without malignant tumors, who underwent vaginal hysterectomy surgery. Fibroblasts at generations 3‑6 of exponential phase cells were selected, and a four‑point bending device was used for 0, 1,333 or 5,333 µ mechanical loading of cells at 0.5 Hz for 4 h. mRNA and protein expression levels of collagen type I α 1 chain (COL1A1), collagen type III α 1 chain (COL3A1), elastin, matrix metalloproteinase (MMP) ‑2 and ‑9, and transforming growth factor (TGF)‑β1 were detected by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. Under increased mechanical strain (5,333 µ), mRNA and protein expression levels of COL1A1, COL3A1 elastin and TGF‑β1 decreased, particularly COL1A1; however, mRNA and protein expression levels of MMP‑2 and ‑9 were significantly increased, compared with the control group (0 µ strain). Following 1,333 µ mechanical strain, mRNA and protein expression levels of COL1A1, COL3A1 elastin and MMP‑2 increased, and MMP‑9 decreased, whereas no significant differences were observed in TGF‑β1 mRNA and protein expression levels. In conclusion, ECM alterations may be involved in pathogenesis of POP, with decreased synthesis and increased degradation of collagen and elastin. Furthermore, the TGF‑β1 signaling pathway may serve an important role in this process and thus may supply a new target and strategy for understanding the etiology and therapy of POP.

  20. Temperature-induced strain release via rugae on the nanometer and micrometer scale in graphene monolayer

    Czech Academy of Sciences Publication Activity Database

    Verhagen, Timotheus; Valeš, Václav; Frank, Otakar; Kalbáč, Martin; Vejpravová, Jana

    2017-01-01

    Roč. 119, Aug (2017), s. 483-491 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : graphene * wrinkle * low temperature Raman mapping * strain * doping * thermal expansion Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Physical chemistry (UFCH-W) Impact factor: 6.337, year: 2016

  1. Hydrogen induced crack propagation in metal under plain-strain deformation

    International Nuclear Information System (INIS)

    Fishgojt, A.V.; Kolachev, B.A.

    1981-01-01

    A model of subcritical crack propagation conditioned by the effect of dissolved hydrogen in the case of plane-strain deformation of high-strength materials, is suggested. It is supposed that diffusion takes place in the isotropic material and hydrogen diffuses in the region of tensile stress maximum before crack tip under the effect of the stress gradient. When hydrogen achieves the critical concentration, microcrack growth takes place. Values of crack growth rates experimentally obtained agree with values calculated according to the suggested formula. Calculation and experimental data on the Ti-6Al-4V alloy, are presented [ru

  2. Genomic diversity of Mycobacterium tuberculosis Beijing strains isolated in Tuscany, Italy, based on large sequence deletions, SNPs in putative DNA repair genes and MIRU-VNTR polymorphisms.

    Science.gov (United States)

    Garzelli, Carlo; Lari, Nicoletta; Rindi, Laura

    2016-03-01

    The Beijing genotype of Mycobacterium tuberculosis is cause of global concern as it is rapidly spreading worldwide, is considered hypervirulent, and is most often associated to massive spread of MDR/XDR TB, although these epidemiological or pathological properties have not been confirmed for all strains and in all geographic settings. In this paper, to gain new insights into the biogeographical heterogeneity of the Beijing family, we investigated a global sample of Beijing strains (22% from Italian-born, 78% from foreign-born patients) by determining large sequence polymorphism of regions RD105, RD181, RD150 and RD142, single nucleotide polymorphism of putative DNA repair genes mutT4 and mutT2 and MIRU-VNTR profiles based on 11 discriminative loci. We found that, although our sample of Beijing strains showed a considerable genomic heterogeneity, yielding both ancient and recent phylogenetic strains, the prevalent successful Beijing subsets were characterized by deletions of RD105 and RD181 and by one nucleotide substitution in one or both mutT genes. MIRU-VNTR analysis revealed 47 unique patterns and 9 clusters including a total of 33 isolates (41% of total isolates); the relatively high proportion of Italian-born Beijing TB patients, often occurring in mixed clusters, supports the possibility of an ongoing cross-transmission of the Beijing genotype to autochthonous population. High rates of extra-pulmonary localization and drug-resistance, particularly MDR, frequently reported for Beijing strains in other settings, were not observed in our survey. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A large portion of meningococcal antigen typing system-negative meningococcal strains from spain is killed by sera from adolescents and infants immunized with 4CMenB.

    Science.gov (United States)

    Abad, R; Biolchi, A; Moschioni, M; Giuliani, M M; Pizza, M; Vázquez, J A

    2015-04-01

    A new vaccine (the 4CMenB 4-component protein vaccine [Bexsero], which includes PorA, factor H-binding protein [fHbp], neisserial heparin-binding antigen [NHBA], and Neisseria adhesin A [NadA]) against serogroup B meningococci has recently been approved for use in people older than age 2 months in Europe, Australia, and Canada. Preapproval clinical efficacy studies are not feasible for invasive meningococcal disease because its incidence is low/very low, and the serum bactericidal antibody (SBA) titer (or the human SBA [hSBA] titer when human complement is used in the assay) has been used as a surrogate marker of protection. However, the hSBA assay cannot be used on a large scale, and therefore, a meningococcal antigen typing system (MATS) was developed. MATS combines conventional PorA genotyping with an enzyme-linked immunosorbent assay (ELISA) that quantifies both the expression and the cross-reactivity of antigenic variants. The assay has been used to evaluate the potential of the 4CMenB meningococcal group B vaccine to cover group B strains in several countries. Some recent data suggest that MATS is a conservative predictor of strain coverage. We used pooled sera from adolescents and infants to test by the hSBA assay 10 meningococcal group B strains isolated in Spain that were negative for the 3 antigens (n = 9) or that had very low levels of the 3 antigens (n = 1) by MATS. We found that all strains were killed by sera from adolescents and that 5 of the 10 strains were also killed, although at a low titer, by sera from infants. Our data confirm that MATS underestimates vaccine coverage. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  4. Characterization and modeling of the magnetic field-induced strain and work output in Ni2MnGa magnetic shape memory alloys

    International Nuclear Information System (INIS)

    Kiefer, B.; Karaca, H.E.; Lagoudas, D.C.; Karaman, I.

    2007-01-01

    This paper is concerned with the experimental characterization and the constitutive modeling of magnetic shape memory alloys (MSMA), in terms of their applicability as actuator materials. The key properties that determine the actuation characteristics are the magnetic field-induced strain (MFIS) and the blocking stress. With the goal of increasing the corresponding actuation output, a material selection strategy was followed which was aimed at obtaining a higher magnetocrystalline anisotropy energy, while keeping the detwinning stress low. This was achieved by choosing a composition in which the separation of the Curie temperature and the martensitic transformation temperatures was large, and then selecting an operating temperature just below the phase transformation temperature. In the selected Ni 51.1 Mn 24.0 Ga 24.9 composition a more than 50% increase of the actuation work output was observed, compared to corresponding data reported in the literature for other off-stoichiometric compositions of the Ni 2 MnGa intermetallic compound. The second part of the paper describes a phenomenological constitutive model that predicts the MFIS hysteresis curves observed in the first part. The model is concerned with the field-induced reorientation of martensitic variants and changes in the magnetic microstructure. Dissipative effects are captured by introducing internal state variables into the free energy function. In its most general form the contributing energy terms are the elastic strain energy, the Zeeman energy, the magnetocrystalline anisotropy energy and appropriate mixing terms. Typical loading cases are considered and the accuracy of the model predictions is evaluated by comparison with the experimental data presented in the first part of this work

  5. Generation of a restriction minus enteropathogenic Escherichia coli E2348/69 strain that is efficiently transformed with large, low copy plasmids

    Directory of Open Access Journals (Sweden)

    Ward Jordan D

    2008-08-01

    Full Text Available Abstract Background Many microbes possess restriction-modification systems that protect them from parasitic DNA molecules. Unfortunately, the presence of a restriction-modification system in a given microbe also hampers genetic analysis. Although plasmids can be successfully conjugated into the enteropathogenic Escherichia coli strain E2348/69 and optimized protocols for competent cell preparation have been developed, we found that a large, low copy (~15 bioluminescent reporter plasmid, pJW15, that we modified for use in EPEC, was exceedingly difficult to transform into E2348/69. We reasoned that a restriction-modification system could be responsible for the low transformation efficiency of E2348/69 and sought to identify and inactivate the responsible gene(s, with the goal of creating an easily transformable strain of EPEC that could complement existing protocols for genetic manipulation of this important pathogen. Results Using bioinformatics, we identified genes in the unfinished enteropathogenic Escherichia coli (EPEC strain E2348/69 genome whose predicted products bear homology to the HsdM methyltransferases, HsdS specificity subunits, and HsdR restriction endonucleases of type I restriction-modification systems. We constructed a strain carrying a deletion of the conserved enzymatic domain of the EPEC HsdR homologue, NH4, and showed that its transformation efficiency was up to four orders of magnitude higher than that of the parent strain. Further, the modification capacity of NH4 remained intact, since plasmids that were normally recalcitrant to transformation into E2348/69 could be transformed upon passage through NH4. NH4 was unaffected in virulence factor production, since bundle forming pilus (BFP subunits and type III secreted (T3S proteins were present at equivalent levels to those seen in E2348/69. Further, NH4 was indistinguishable from E2348/69 in tissue culture infection model assays of localized adherence and T3S. Conclusion We

  6. Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions.

    Science.gov (United States)

    Bazant, Martin Z; Kilic, Mustafa Sabri; Storey, Brian D; Ajdari, Armand

    2009-11-30

    The venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e approximately 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V approximately 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the "compact layer" and "shear plane" effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions.

  7. Generation of Mid-Ocean Ridge Geometries by Strain Induced Damage

    Science.gov (United States)

    Hieronymus, C. F.

    2001-12-01

    Motivated by the success of wax models in which spreading segments, transform faults, and overlapping spreading centers form in a thin plate of solid wax under tension overlying a reservoir of molten wax, the dynamics of an elastic plate with damage is investigated. The effects of the underlying medium are neglected. A thin elastic plate with localized weaknesses in the elastic moduli is exposed to a deviatoric stress field. Stresses and strains are concentrated near the boundaries and inside the weak zones. Weakening of the material is assumed to occur where stress and strain are high, i.e. in regions of high elastic energy. The weak zones typically develop into linear bands of reduced elastic strength resembling fractures and shear zones. Different dependencies of the elastic moduli on damage result in different geometries of weak zones. An initially circular weakness has two locations of normal stress concentration; reduction of bulk and shear modulus there results in formation of an opening mode fracture with low resistance to any type of deformation. Two such fractures offset from each other and propagating toward each other interact by overlapping and curving toward each other. This overlapping geometry, which is observed along the East Pacific Rise, is stable; the fractures do not cut each other off. Introduction of a second type of damage causes the overlapping region between the two fractures to fail, and the more commonly observed transform offset develops. With another type of damage-strain dependency, oblique spreading occurs along lines 45o from the applied stress. Such patterns form frequently in certain types of wax, but are not observed along mid-ocean ridges. The model results suggest that it is the rheology of the solid plate, not the dynamics of the underlying mantle that control the morphology of the spreading ridge. Standard damage theory uses only a single damage parameter. The fact that the failure modes described above are limited to systems

  8. RNA of Enterococcus faecalis Strain EC-12 Is a Major Component Inducing Interleukin-12 Production from Human Monocytic Cells.

    Directory of Open Access Journals (Sweden)

    Ryoichiro Nishibayashi

    Full Text Available Interleukin-12 (IL-12 is an important cytokine for the immunomodulatory effects of lactic acid bacteria (LAB. Using murine immune cells, we previously reported that the RNA of Enterococcus faecalis EC-12, a LAB strain exerting probiotic-like beneficial effects, is the major IL-12-inducing immunogenic component. However, it was recently revealed that bacterial RNA can be a ligand for Toll-like receptor (TLR 13, which is only expressed in mice. Because TLR13 is not expressed in humans, the immuno-stimulatory and -modulatory effects of LAB RNA in human cells should be augmented excluding TLR13 contribution. In experiment 1 of this study, the role of LAB RNA in IL-12 induction in human immune cells was studied using three LAB strains, E.faecalis EC-12, Lactobacillus gasseri JCM5344, and Bifidobacterium breve JCM1192. RNase A treatment of heat-killed LAB significantly decreased the IL-12 production of human peripheral blood mononuclear cells on stimulation, while RNase III treatment revealed virtually no effects. Further, IL-12 production against heat-killed E. faecalis EC-12 was abolished by depleting monocytes. These results demonstrated that single stranded RNA (ssRNA of LAB is a strong inducer of IL-12 production from human monocytes. In experiment 2, major receptor for ssRNA of E. faecalis EC-12 was identified using THP-1 cells, a human monocytic cell line. The type of RNA molecules of E. faecalis EC-12 responsible for IL-12 induction was also identified. IL-12 production induced by the total RNA of E. faecalis EC-12 was significantly reduced by the treatment of siRNA for TLR8 but not for TLR7. Furthermore, both 23S and 16S rRNA, but not mRNA, of E. faecalis EC-12 markedly induced IL-12 production from THP-1 cells. These results suggested that the recognition of ssRNA of E. faecalis EC-12 was mediated by TLR8 and that rRNA was the RNA molecule that exhibited IL-12-inducing ability in human cells.

  9. Deformation induced dynamic recrystallization and precipitation strengthening in an Mg−Zn−Mn alloy processed by high strain rate rolling

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jimiao; Song, Min [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Yan, Hongge [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Yang, Chao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Ni, Song, E-mail: song.ni@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2016-11-15

    The microstructure of a high strain-rate rolled Mg−Zn−Mn alloy was investigated by transmission electron microscopy to understand the relationship between the microstructure and mechanical properties. The results indicate that: (1) a bimodal microstructure consisting of the fine dynamic recrystallized grains and the largely deformed grains was formed; (2) a large number of dynamic precipitates including plate-like MgZn{sub 2} phase, spherical MgZn{sub 2} phase and spherical Mn particles distribute uniformly in the grains; (3) the major facets of many plate-like MgZn{sub 2} precipitates deviated several to tens of degrees (3°–30°) from the matrix basal plane. It has been shown that the high strength of the alloy is attributed to the formation of the bimodal microstructure, dynamic precipitation, and the interaction between the dislocations and the dynamic precipitates. - Highlights: •A bimodal microstructure was formed in a high strain-rate rolled Mg−Zn−Mn alloy. •Plate-like MgZn{sub 2}, spherical MgZn{sub 2} and spherical Mn phases were observed. •The major facet of the plate-like MgZn{sub 2} deviated from the matrix basal plane.

  10. AI-2 signalling is induced by acidic shock in probiotic strains of Lactobacillus spp

    DEFF Research Database (Denmark)

    Moslehi Jenabian, Saloomeh; Gori, Klaus; Jespersen, Lene

    2009-01-01

    Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates...... important physiological traits and a variety of adaptive processes in different bacteria. The aim of this study was to investigate the effect of acidic stress on LuxS-mediated quorum sensing (AI-2 signalling) in four probiotic strains of different Lactobacillus species. Initially, the production of AI-2...... concomitant with the reduction of pH, reaching maximum at late exponential phase (L. rhamnosus GG) or at stationary phase (L. salivarius UCC118, L. acidophilus NCFM and L. johnsonii NCC533). Acidic shock experiments were conducted on L. rhamnosus GG and L. acidophilus NCFM after exposure to different acidic...

  11. Brucella suis vaccine strain 2 induces endoplasmic reticulum stress that affects intracellular replication in goat trophoblast cells in vitro

    Directory of Open Access Journals (Sweden)

    Xiangguo eWang

    2016-02-01

    Full Text Available Brucella has been reported to impair placental trophoblasts, a cellular target where Brucella efficiently replicates in association with the endoplasmic reticulum (ER, and ultimately trigger abortion in pregnant animals. However, the precise effects of Brucella on trophoblast cells remain unclear. Here, we describe the infection and replication of Brucella suis vaccine strain 2 (B.suis.S2 in goat trophoblast cells (GTCs and the cellular and molecular responses induced in vitro. Our studies demonstrated that B.suis.S2 was able to infect and proliferate to high titers, hamper the proliferation of GTCs and induce apoptosis due to ER stress. Tunicamycin (Tm, a pharmacological chaperone that strongly mounts ER stress-induced apoptosis, inhibited B.suis.S2 replication in GTCs. In addition, 4 phenyl butyric acid (4-PBA, a pharmacological chaperone that alleviates ER stress-induced apoptosis, significantly enhanced B.suis.S2 replication in GTCs. The Unfolded Protein Response (UPR chaperone molecule GRP78 also promoted B.suis.S2 proliferation in GTCs by inhibiting ER stress-induced apoptosis. We also discovered that the IRE1 pathway, but not the PERK or ATF6 pathway, was activated in the process. However, decreasing the expression of phosphoIRE1α and IRE1α proteins with Irestatin 9389 (IRE1 antagonist in GTCs did not affect the proliferation of B.suis.S2. Although GTC implantation was not affected upon B.suis.S2 infection, progesterone secretion was suppressed, and prolactin and estrogen secretion increased; these effects were accompanied by changes in the expression of genes encoding key steroidogenic enzymes. This study systematically explored the mechanisms of abortion in Brucella infection from the viewpoint of pathogen invasion, ER stress and reproductive endocrinology. Our findings may provide new insight for understanding the mechanisms involved in goat abortions caused by Brucella infection.

  12. Establishment of the cytoplasmic incompatibility-inducing Wolbachia strain wMel in an important agricultural pest insect.

    Science.gov (United States)

    Zhou, Xiao-Fei; Li, Zheng-Xi

    2016-12-16

    The wMel Wolbachia strain was known for cytoplasmic incompatibility (CI)-induction and blocking the transmission of dengue. However, it is unknown whether it can establish and induce CI in a non-dipteran host insect. Here we artificially transferred wMel from Drosophila melanogaster into the whitefly Bemisia tabaci. Fluorescence in situ hybridisation demonstrated that wMel had successfully transfected the new host. Reciprocal crossing was conducted with wMel-transfected and wild-type isofemale lines, indicating that wMel could induce a strong CI without imposing significant cost on host fecundity. We then determined the maternal transmission efficiency of wMel in the offspring generations, showing a fluctuating trend over a period of 12 generations. We thus detected the titre of wMel during different developmental stages and in different generations by using real-time quantitative PCR, revealing a similar fluctuating mode, but it was not significantly correlated with the dynamics of transmission efficiency. These results suggest that wMel can be established in B.tabaci, a distantly related pest insect of agricultural importance; moreover, it can induce a strong CI phenotype in the recipient host insect, suggesting a potential for its use in biological control of B. tabaci.

  13. Avian influenza A virus PB2 promotes interferon type I inducing properties of a swine strain in porcine dendritic cells

    International Nuclear Information System (INIS)

    Ocaña-Macchi, Manuela; Ricklin, Meret E.; Python, Sylvie; Monika, Gsell-Albert; Stech, Jürgen; Stech, Olga; Summerfield, Artur

    2012-01-01

    The 2009 influenza A virus (IAV) pandemic resulted from reassortment of avian, human and swine strains probably in pigs. To elucidate the role of viral genes in host adaptation regarding innate immune responses, we focussed on the effect of genes from an avian H5N1 and a porcine H1N1 IAV on infectivity and activation of porcine GM-CSF-induced dendritic cells (DC). The highest interferon type I responses were achieved by the porcine virus reassortant containing the avian polymerase gene PB2. This finding was not due to differential tropism since all viruses infected DC equally. All viruses equally induced MHC class II, but porcine H1N1 expressing the avian viral PB2 induced more prominent nuclear NF-κB translocation compared to its parent IAV. The enhanced activation of DC may be detrimental or beneficial. An over-stimulation of innate responses could result in either pronounced tissue damage or increased resistance against IAV reassortants carrying avian PB2.

  14. Avian influenza A virus PB2 promotes interferon type I inducing properties of a swine strain in porcine dendritic cells

    Energy Technology Data Exchange (ETDEWEB)

    Ocana-Macchi, Manuela; Ricklin, Meret E.; Python, Sylvie; Monika, Gsell-Albert [Institute of Virology and Immunoprophylaxis, Mittelhaeusern (Switzerland); Stech, Juergen; Stech, Olga [Friedrich-Loeffler Institut, Greifswald-Insel Riems (Germany); Summerfield, Artur, E-mail: artur.summerfield@ivi.admin.ch [Institute of Virology and Immunoprophylaxis, Mittelhaeusern (Switzerland)

    2012-05-25

    The 2009 influenza A virus (IAV) pandemic resulted from reassortment of avian, human and swine strains probably in pigs. To elucidate the role of viral genes in host adaptation regarding innate immune responses, we focussed on the effect of genes from an avian H5N1 and a porcine H1N1 IAV on infectivity and activation of porcine GM-CSF-induced dendritic cells (DC). The highest interferon type I responses were achieved by the porcine virus reassortant containing the avian polymerase gene PB2. This finding was not due to differential tropism since all viruses infected DC equally. All viruses equally induced MHC class II, but porcine H1N1 expressing the avian viral PB2 induced more prominent nuclear NF-{kappa}B translocation compared to its parent IAV. The enhanced activation of DC may be detrimental or beneficial. An over-stimulation of innate responses could result in either pronounced tissue damage or increased resistance against IAV reassortants carrying avian PB2.

  15. Large vein injection alleviates rocuronium-induced pain in gynaecologic patients.

    Science.gov (United States)

    Zhang, Xing-Mei; Wang, Qun; Wang, Wei-Si; Wang, Meng

    2017-08-01

    Rocuronium-induced pain upon injection is very common in the clinical setting. Using the antecubital rather than the hand vein can avoid pain due to propofol injection. We aimed to investigate whether the use of the antecubital vein for injection would alleviate rocuronium-induced pain in a similar fashion. Sixty patients (ASA classes I and II) scheduled for gynaecologic laparoscopy were randomised into two groups. Rocuronium (0.6mg/kg) was injected either into the vein on the dorsum of the hand (group D) or a large vein in the antecubital fossa (group A). Pain was assessed and recorded using a four-point scale. Compared with group D, the incidence of pain and severe pain was lower in group A patients. The rate of no pain was also higher in group A patients. The incidence and severity of rocuronium-induced injection pain were significantly alleviated via use of a large vein for rocuronium injection. Copyright © 2016 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

  16. Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina [v1; ref status: indexed, http://f1000r.es/o4

    Directory of Open Access Journals (Sweden)

    Lars Behrendt

    2013-02-01

    Full Text Available Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared radiation (NIR for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS. In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS. More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. To our knowledge, this is the first study of ROS generation associated with NIR-driven oxygenic photosynthesis and it suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance.

  17. Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina [v2; ref status: indexed, http://f1000r.es/z7

    Directory of Open Access Journals (Sweden)

    Lars Behrendt

    2013-03-01

    Full Text Available Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared-radiation (NIR for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS. In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS. More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance.

  18. Effects of induced magnetic field on large scale pulsed MHD generator with two phase flow

    International Nuclear Information System (INIS)

    Ishikawa, M.; Koshiba, Y.; Matsushita, T.

    2004-01-01

    A large pulsed MHD generator 'SAKHALIN' was constructed in Russia (the former Soviet-Union) and operated with solid fuels. The 'SAKHALIN' with the channel length of 4.5 m could demonstrate the electric power output of 510 MW. The effects of induced magnetic field and two phase flow on the shock wave within the 'SAKHALIN' generator have been studied by time dependent, one dimensional analyses. It has been shown that the magnetic Reynolds number is about 0.58 for Run No. 1, and the induced magnetic flux density is about 20% at the entrance and exit of the MHD channel. The shock wave becomes stronger when the induced magnetic field is taken into account, when the operation voltage becomes low. The working gas plasma contains about 40% of liquid particles (Al 2 O 3 ) in weight, and the present analysis treats the liquid particles as another gas. In the case of mono-phase flow, the sharp shock wave is induced when the load voltage becomes small such as 500 V with larger Lorentz force, whereas in the case of two phase flow, the shock wave becomes less sharp because of the interaction with liquid particles

  19. Glass-like dynamics of the strain-induced coil/helix transition on a permanent polymer network.

    Science.gov (United States)

    Ronsin, O; Caroli, C; Baumberger, T

    2016-02-14

    We study the stress response to a step strain of covalently bonded gelatin gels in the temperature range where triple helix reversible crosslink formation is prohibited. We observe slow stress relaxation towards a T-dependent finite asymptotic level. We show that this is assignable to the strain-induced coil → helix transition, previously evidenced by Courty et al. [Proc. Natl. Acad. Sci. U. S. A. 102, 13457 (2005)], of a fraction of the polymer strands. Relaxation proceeds, in a first stage, according to a stretched exponential dynamics, then crosses over to a terminal simple exponential decay. The respective characteristic times τK and τf exhibit an Arrhenius-like T-dependence with an associated energy E incompatibly larger than the activation barrier height for the isomerisation process which sets the clock for an elementary coil → helix transformation event. We tentatively assign this glass-like slowing down of the dynamics to the long-range couplings due to the mechanical noise generated by the local elementary events in this random elastic medium.

  20. Near-ultraviolet radiation-induced damage using an actinic reticuloid strain as a possible sensitive model

    International Nuclear Information System (INIS)

    Kralli, A.

    1987-01-01

    The introduction to this thesis consists of a review of current concepts regarding the effects of ultraviolet radiation on living cells. Actinic reticuloid, a disease condition for which a near-ultraviolet radiation cellular sensitivity has been proposed as an underlying cause, is described. The experimental work, the broad aim of which is to expand existing knowledge of the effects of near-ultraviolet radiation that may lead to cell lethality, has centred upon the irradiation of a normal human skin fibroblast strain, GM730, and a strain derived from an actinic reticuloid patient, AR6LO. Parts 1 and 2 examine the effects of the irradiation on both normal and actinic fibroblast sensitivities to a range of ultraviolet wavelengths. The next two sections include observations on the protective effect of Trolox-C, a vitamin E analogue and the sensitization resulting from the replacement of the irradiation medium by a deuterated one, using both normal and actinic reticuloid fibroblasts. The final part examines broad-band near- and far-ultraviolet radiation induced membrane damage by the use of radioactively labelled rubidium as a potassium analogue. (author)

  1. Strain-induced Weyl and Dirac states and direct-indirect gap transitions in group-V materials

    Science.gov (United States)

    Moynihan, Glenn; Sanvito, Stefano; O'Regan, David D.

    2017-12-01

    We perform comprehensive density-functional theory calculations on strained two-dimensional phosphorus (P), arsenic (As) and antimony (Sb) in the monolayer, bilayer, and bulk α-phase, from which we compute the key mechanical and electronic properties of these materials. Specifically, we compute their electronic band structures, band gaps, and charge-carrier effective masses, and identify the qualitative electronic and structural transitions that may occur. Moreover, we compute the elastic properties such as the Young’s modulus Y; shear modulus G; bulk modulus B ; and Poisson ratio ν and present their isotropic averages of as well as their dependence on the in-plane orientation, for which the relevant expressions are derived. We predict strain-induced Dirac states in the monolayers of As and Sb and the bilayers of P, As, and Sb, as well as the possible existence of Weyl states in the bulk phases of P and As. These phases are predicted to support charge velocities up to 106 m {{\\text{s}}-1} and, in some highly anisotropic cases, permit one-dimensional ballistic conductivity in the puckered direction. We also predict numerous band gap transitions for moderate in-plane stresses. Our results contribute to the mounting evidence for the utility of these materials, made possible by their broad range in tuneable properties, and facilitate the directed exploration of their potential application in next-generation electronics.

  2. A sequence in subdomain 2 of DBL1α of Plasmodium falciparum erythrocyte membrane protein 1 induces strain transcending antibodies.

    Directory of Open Access Journals (Sweden)

    Karin Blomqvist

    Full Text Available Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1 present at the surface of the parasitized red blood cell (pRBC confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1α previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14 were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1α-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1α antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surface.

  3. Direct investigations on strain-induced cold crystallization behavior and structure evolutions in amorphous poly(lactic acid) with SAXS and WAXS measurements

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Li, Hongfei; Zhang, Wenyang

    2016-01-01

    scanning calorimetry (DSC) measurements. The data obtained from the stretched samples within 70-90 degrees C showed that all of the formed crystals are disordered alpha' form with more compact chain packing than that of the cold crystallization. Upon stretching at 70 degrees C, the mesocrystal appears......Strain-induced cold crystallization behavior and structure evolution of amorphous poly(lactic acid) (PLA) stretched within 70-90 degrees C were investigated via in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements as well as differential...... in strain-induced crystallization behavior of amorphous PLA within 70-90 degrees C can be attributed to the competition between chain orientation caused by stretching and chain relaxation. It was proposed that the strain-induced mesocrystal/crystal and the lamellae are formed from the mesophase originally...

  4. Human vaccination against Plasmodium vivax Duffy-binding protein induces strain-transcending antibodies

    OpenAIRE

    Payne, Ruth O.; Silk, Sarah E.; Elias, Sean C.; Milne, Kathryn H.; Rawlinson, Thomas A.; Llewellyn, David; Shakri, A. Rushdi; Jin, Jing; Labb?, Genevi?ve M.; Edwards, Nick J.; Poulton, Ian D.; Roberts, Rachel; Farid, Ryan; J?rgensen, Thomas; Alanine, Daniel G.W.

    2017-01-01

    BACKGROUND: Plasmodium vivax is the most widespread human malaria geographically; however, no effective vaccine exists. Red blood cell invasion by the P. vivax merozoite depends on an interaction between the Duffy antigen receptor for chemokines (DARC) and region II of the parasite's Duffy-binding protein (PvDBP_RII). Naturally acquired binding-inhibitory antibodies against this interaction associate with clinical immunity, but it is unknown whether these responses can be induced by human vac...

  5. Efficient Meshfree Large Deformation Simulation of Rainfall Induced Soil Slope Failure

    Science.gov (United States)

    Wang, Dongdong; Li, Ling

    2010-05-01

    An efficient Lagrangian Galerkin meshfree framework is presented for large deformation simulation of rainfall-induced soil slope failure. Detailed coupled soil-rainfall seepage equations are given for the proposed formulation. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is maintained. The initiation and evolution of progressive failure in the soil slope is modeled by the coupled constitutive equations of isotropic damage and Drucker-Prager pressure-dependent plasticity. The gradient smoothing in the stabilized conforming integration also serves as a non-local regularization of material instability and consequently the present method is capable of effectively capture the shear band failure. The efficacy of the present method is demonstrated by simulating the rainfall-induced failure of two typical soil slopes.

  6. Flow induced vibration of the large-sized sodium valve for MONJU

    International Nuclear Information System (INIS)

    Sato, K.

    1977-01-01

    Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

  7. Flow induced vibration of the large-sized sodium valve for MONJU

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K [Sodium Engineering Division, O-arai Engineering Centre, Power Reactor and Nuclear Fuel Development Corporation, Nariata-cho, O-arai Machi, Ibaraki-ken (Japan)

    1977-12-01

    Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

  8. A large area position-sensitive ionization chamber for heavy-ion-induced reaction studies

    CERN Document Server

    Pant, L M; Dinesh, B V; Thomas, R G; Saxena, A; Sawant, Y S; Choudhury, R K

    2002-01-01

    A large area position-sensitive ionization chamber with a wide dynamic range has been developed to measure the mass, charge and energy of the heavy ions and the fission fragments produced in heavy-ion-induced reactions. The split anode geometry of the detector makes it suitable for both particle identification and energy measurements for heavy ions and fission fragments. The detector has been tested with alpha particles from sup 2 sup 4 sup 1 Am- sup 2 sup 3 sup 9 Pu source, fission fragments from sup 2 sup 5 sup 2 Cf and the heavy-ion beams from the 14UD Mumbai Pelletron accelerator facility. Using this detector, measurements on mass and total kinetic energy distributions in heavy-ion-induced fusion-fission reactions have been carried out for a wide range of excitation energies. Results on deep inelastic collisions and mass-energy correlations on different systems using this detector setup are discussed.

  9. On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

    Directory of Open Access Journals (Sweden)

    B. Xiong

    2016-04-01

    Full Text Available The influence of crystalline microstructure and molecular topology on the strain-induced fibrillar transformation of semi-crystalline polyethylenes having various chemical structures including co-unit content and molecular weight and crystallized under various thermal treatments was studied by in situ SAXS at different draw temperatures. The long period of the nascent microfibrils, Lpf, proved to be strongly dependent on the draw temperature but non-sensitive to the initial crystallization conditions. Lpf was smaller than the initial long period. Both findings have been ascribed to the straininduced melting-recrystallization process as generally claimed in the literature. The microfibrils diameter, Df, was shown to depend on the draw temperature and initial microstructure in a different way as Lpf. The evolution of Df was shown to correlate with the interfacial layer thickness that mainly depends on the chemical structure of the chains. It was concluded that, in contrast to Lpf, the microfibril diameter should not be directly sensitive to the strain-induced melting-recrystallization. The proposed scenario is that after the generation of the protofibrils by fragmentation of the crystalline lamellae at yielding, the diameter of the microfibril during the course of their stabilization should be governed by the chain-unfolding and subsequent aggregation of the unfolded chains onto the lateral surface of the microfibrils. The morphogenesis of the microfibrils should therefore essentially depend on the chemical structure of the polymer that governs its crystallization ability, its chain topology and subsequently its fragmentation process at yielding. This scenario is summed up in a sketch.

  10. Lactobacillus reuteri prevents diet-induced obesity, but not atherosclerosis, in a strain dependent fashion in Apoe-/- mice.

    Directory of Open Access Journals (Sweden)

    Frida Fåk

    Full Text Available OBJECTIVE: To investigate whether the specific strains of Lactobacillus reuteri modulates the metabolic syndrome in Apoe-/- mice. METHODS: 8 week-old Apoe-/- mice were subdivided into four groups who received either L. reuteri ATCC PTA 4659 (ATCC, DSM 17938 (DSM, L6798, or no bacterial supplement in the drinking water for 12 weeks. The mice were fed a high-fat Western diet with 0.2% cholesterol and body weights were monitored weekly. At the end of the study, oral glucose and insulin tolerance tests were conducted. In addition, adipose and liver weights were recorded along with analyses of mRNA expression of ileal Angiopoietin-like protein 4 (Angptl4, the macrophage marker F4/80 encoded by the gene Emr1 and liver Acetyl-CoA carboxylase 1 (Acc1, Fatty acid synthase (Fas and Carnitine palmitoyltransferase 1a (Cpt1a. Atherosclerosis was assessed in the aortic root region of the heart. RESULTS AND CONCLUSIONS: Mice receiving L. reuteri ATCC gained significantly less body weight than the control mice, whereas the L6798 mice gained significantly more. Adipose and liver weights were also reduced in the ATCC group. Serum insulin levels were lower in the ATCC group, but no significant effects were observed in the glucose or insulin tolerance tests. Lipogenic genes in the liver were not altered by any of the bacterial treatments, however, increased expression of Cpt1a was found in the ATCC group, indicating increased β-oxidation. Correspondingly, the liver trended towards having lower fat content. There were no effects on inflammatory markers, blood cholesterol or atherosclerosis. In conclusion, the probiotic L. reuteri strain ATCC PTA 4659 partly prevented diet-induced obesity, possibly via a previously unknown mechanism of inducing liver expression of Cpt1a.

  11. AI-2 signalling is induced by acidic shock in probiotic strains of Lactobacillus spp.

    Science.gov (United States)

    Moslehi-Jenabian, Saloomeh; Gori, Klaus; Jespersen, Lene

    2009-11-15

    Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates important physiological traits and a variety of adaptive processes in different bacteria. The aim of this study was to investigate the effect of acidic stress on LuxS-mediated quorum sensing (AI-2 signalling) in four probiotic strains of different Lactobacillus species. Initially, the production of AI-2-like molecule was investigated in four strains of Lactobacillus spp. at standard growth conditions using Vibrio harveyi bioluminescence assay. Species variation in AI-2 activity was observed. AI-2 activity started at early-exponential growth phase and increased during the mid-exponential phase concomitant with the reduction of pH, reaching maximum at late exponential phase (L. rhamnosus GG) or at stationary phase (L. salivarius UCC118, L. acidophilus NCFM and L. johnsonii NCC533). Acidic shock experiments were conducted on L. rhamnosus GG and L. acidophilus NCFM after exposure to different acidic shocks (pH 5.0, 4.0 and 3.0) and to pH 6.5 as control, measuring AI-2 activity and transcription of the luxS gene. AI-2 activity increased by lowering the pH in a dose dependent manner and was negatively influenced by acid adaptation. In both species, the luxS gene was repressed after exposure to pH 6.5 as control. However, after acidic shock (pH 4.0) a transient response of luxS gene was observed and the transcription augmented over time, reaching a maximum level and decreased subsequently. Acid adaptation of cells attenuated the transcription of this gene. Based on the observations done in the present study, the luxS gene appears to have a clear role in acidic stress response in probiotic lactobacilli. This might be important in the survival of these bacteria during the passage

  12. Distribution of strain type and antimicrobial susceptibility of Escherichia coli isolates causing meningitis in a large urban setting in Brazil.

    Science.gov (United States)

    Berman, Hillary; Barberino, Maria Goreth; Moreira, Edson Duarte; Riley, Lee; Reis, Joice N

    2014-05-01

    The clinical management of meningitis caused by Escherichia coli is greatly complicated when the organism becomes resistant to broad-spectrum antibiotics. We sought to characterize the antimicrobial susceptibilities, sequence types (ST), and presence of known drug resistance genes of E. coli isolates that caused meningitis between 1996 and 2011 in Salvador, Brazil. We then compared these findings to those for E. coli isolates from community-acquired urinary tract infections (UTI) that occurred during the same time period and in the same city. We found that 19% of E. coli isolates from cases of meningitis and less than 1% of isolates from UTI were resistant to third-generation cephalosporins. The sequence types of E. coli isolates from cases of meningitis included ST131, ST69, ST405, and ST62, which were also found among isolates from UTI. Additionally, among the E. coli isolates that were resistant to third-generation cephalosporins, we found genes that encode the extended-spectrum beta-lactamases CTX-M-2, CTX-M-14, and CTX-M-15. These observations demonstrate that compared to E. coli strains isolated from cases of community-acquired UTI, those isolated from cases of meningitis are more resistant to third-generation cephalosporins, even though the same sequence types are shared between the two forms of extraintestinal infections.

  13. Three dimensional strained semiconductors

    Science.gov (United States)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  14. Lactobacillus salivarius strain FDB89 induced longevity in Caenorhabditis elegans by dietary restriction.

    Science.gov (United States)

    Zhao, Yang; Zhao, Liang; Zheng, Xiaonan; Fu, Tianjiao; Guo, Huiyuan; Ren, Fazheng

    2013-04-01

    In this study, we utilized the nematode Caenorhabditis elegans to assess potential life-expanding effect of Lactobacillus salivarius strain FDB89 (FDB89) isolated from feces of centenarians in Bama County (Guangxi, China). This study showed that feeding FDB89 extended the mean life span in C. elegans by up to 11.9% compared to that of control nematodes. The reduced reproductive capacities, pharyngeal pumping rate, growth, and increased superoxide dismutase (SOD) activity and XTT reduction capacity were also observed in FDB89 feeding worms. To probe the anti-aging mechanism further, we incorporated a food gradient feeding assay and assayed the life span of eat-2 mutant. The results demonstrated that the maximal life span of C. elegans fed on FDB89 was achieved at the concentration of 1.0 mg bacterial cells/plate, which was 10-fold greater than that of C. elegans fed on E. coli OP50 (0.1 mg bacterial cells/plate). However, feeding FDB89 could not further extend the life span of eat-2 mutant. These results indicated that FDB89 modulated the longevity of C. elegans in a dietary restriction-dependent manner and expanded the understanding of anti-aging effect of probiotics.

  15. Mixed Lactobacillus plantarum Strains Inhibit Staphylococcus aureus Induced Inflammation and Ameliorate Intestinal Microflora in Mice.

    Science.gov (United States)

    Ren, Dayong; Gong, Shengjie; Shu, Jingyan; Zhu, Jianwei; Rong, Fengjun; Zhang, Zhenye; Wang, Di; Gao, Liangfeng; Qu, Tianming; Liu, Hongyan; Chen, Ping

    2017-01-01

    Objective . Staphylococcus aureus is an important pathogen that causes intestinal infection. We examined the immunomodulatory function of single and mixed Lactobacillus plantarum strains, as well as their impacts on the structure of the microbiome in mice infected with Staphylococcus aureus . The experiment was divided into three groups: protection, treatment, and control. Serum IFN- γ and IL-4 levels, as well as intestinal sIgA levels, were measured during and 1 week after infection with Staphylococcus aureus with and without Lactobacillus plantarum treatment. We used 16s rRNA tagged sequencing to analyze microbiome composition. IFN- γ /IL-4 ratio decreased significantly from infection to convalescence, especially in the mixed Lactobacillus plantarum group. In the mixed Lactobacillus plantarum group the secretion of sIgA in the intestine of mice (9.4-9.7 ug/mL) was significantly higher than in the single lactic acid bacteria group. The dominant phyla in mice are Firmicutes , Bacteroidetes , and Proteobacteria . Treatment with mixed lactic acid bacteria increased the anti-inflammatory factor and the secretion of sIgA in the intestine of mice infected with Staphylococcus aureus and inhibited inflammation.

  16. Strain-induced metal-insulator phase coexistence in perovskite manganites.

    Science.gov (United States)

    Ahn, K H; Lookman, T; Bishop, A R

    2004-03-25

    The coexistence of distinct metallic and insulating electronic phases within the same sample of a perovskite manganite, such as La(1-x-y)Pr(y)Ca(x)MnO3, presents researchers with a tool for tuning the electronic properties in materials. In particular, colossal magnetoresistance in these materials--the dramatic reduction of resistivity in a magnetic field--is closely related to the observed texture owing to nanometre- and micrometre-scale inhomogeneities. Despite accumulated data from various high-resolution probes, a theoretical understanding for the existence of such inhomogeneities has been lacking. Mechanisms invoked so far, usually based on electronic mechanisms and chemical disorder, have been inadequate to describe the multiscale, multiphase coexistence within a unified picture. Moreover, lattice distortions and long-range strains are known to be important in the manganites. Here we show that the texturing can be due to the intrinsic complexity of a system with strong coupling between the electronic and elastic degrees of freedom. This leads to local energetically favourable configurations and provides a natural mechanism for the self-organized inhomogeneities over both nanometre and micrometre scales. The framework provides a physical understanding of various experimental results and a basis for engineering nanoscale patterns of metallic and insulating phases.

  17. Strain-Induced Rolled Thin Films for Lightweight Tubular Thermoelectric Generators

    KAUST Repository

    Singh, Devendra; Kutbee, Arwa T.; Ghoneim, Mohamed T.; Hussain, Aftab M.; Hussain, Muhammad Mustafa

    2017-01-01

    with unprecedented length (up to seamless 4 cm and further expandable) are shown. This length allows for large temperature differences between the hot and the cold ends, a critical but untapped enabler for high power generation. Compared with a flat slab, better area

  18. Large potential change induced by pellet injection in JIPP T-IIU tokamak plasmas

    International Nuclear Information System (INIS)

    Hamada, Y.; Sato, K.N.; Sakakita, H.

    1995-05-01

    A large, rapid change in the local plasma potential is found to be induced by off-axis hydrogen ice-pellet injection into a tokamak plasma. The polarity of the rapid change is reversed when the pellet is injected into the upper and lower halves of the poloidal plasma cross-section. This change can be interpreted as being due to the gradient-B drift of particles in the high-density plasmas of the pellet cloud, before the increase of the plasma density due to the ablation becomes uniform on the magnetic surface. (author)

  19. HI responses induced by seasonal influenza vaccination are associated with clinical protection and with seroprotection against non-homologous strains.

    Science.gov (United States)

    Luytjes, Willem; Enouf, Vincent; Schipper, Maarten; Gijzen, Karlijn; Liu, Wai Ming; van der Lubben, Mariken; Meijer, Adam; van der Werf, Sylvie; Soethout, Ernst C

    2012-07-27

    Vaccination against influenza induces homologous as well as cross-specific hemagglutination inhibiting (HI) responses. Induction of cross-specific HI responses may be essential when the influenza strain does not match the vaccine strain, or even to confer a basic immune response against a pandemic influenza virus. We carried out a clinical study to evaluate the immunological responses after seasonal vaccination in healthy adults 18-60 years of age, receiving the yearly voluntary vaccination during the influenza season 2006/2007. Vaccinees of different age groups were followed for laboratory confirmed influenza (LCI) and homologous HI responses as well as cross-specific HI responses against the seasonal H1N1 strain of 2008 and pandemic H1N1 virus of 2009 (H1N1pdm09) were determined. Homologous HI titers that are generally associated with protection (i.e. seroprotective HI titers ≥40) were found in more than 70% of vaccinees. In contrast, low HI titers before and after vaccination were significantly associated with seasonal LCI. Cross-specific HI titers ≥40 against drifted seasonal H1N1 were found in 69% of vaccinees. Cross-specific HI titers ≥40 against H1N1pdm09 were also significantly induced, especially in the youngest age group. More specifically, cross-specific HI titers ≥40 against H1N1pdm09 were inversely correlated with age. We did not find a correlation between the subtype of influenza which was circulating at the age of birth of the vaccinees and cross-specific HI response against H1N1pdm09. These data indicate that the HI titers before and after vaccination determine the vaccination efficacy. In addition, in healthy adults between 18 and 60 years of age, young adults appear to be best able to mount a cross-protective HI response against H1N1pdm09 or drifted seasonal influenza after seasonal vaccination. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. TCDD-induced transcriptional profiles in different mouse strains that have an identical AhR genotype

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qing; Suzuki, Junko S.; Tohyama, Chiharu; Ohsako, Seiichiroh [Environmental Health Sciences Division, National Institute for Environmental Studies, Onogawa, Tsukuba (Japan); Takei, Teiji [Environmental Health and Safety Division, Ministry of the Environment, Kasumigaseki, Tokyo (Japan); Lin, Tinmin; Peterson, R.E. [Wisconsin Univ., Wisconsin, MA (United States). School of Pharmacy and Molecular and Environmental Toxicology Center

    2004-09-15

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant that is known to cause hepatotoxicity, teratogenicity and carcinogenicity. A characteristic feature in the toxicity of TCDD is exceptionally large differences in susceptibility among animal species or even strains belonging to the same species. These strain differences in susceptibility to TCDD have now been elucidated to be due to the difference in ligand binding affinity or transcriptional activity of the aryl hydrocarbon receptor (AhR). Actually the C57BL/6 type AhR (AhR{sup b}) showed 6-fold higher ligand binding affinity than the DBA/2 type AhR (AhR{sup d}). The H/W rat AhR has a C-terminal truncation of the transactivating domain compared to the L-E rat AhR. On the other hand, there is considerable species variability in response sensitivity to TCDD that cannot be ascribed simply to polymorphisms of the AhR gene. A non-AhR gene susceptibility loci for hepatic porphyria has been observed in mice treated with iron compounds prior to TCDD injection by using a quantitative trait locus analysis of an F2 intercross between susceptible C57BL/6 and resistant DBA/2 stains. In the rat, a gene B with Han/Wistar type AhR is likely to be involved in resistance to TCDD lethality. These observations suggest that other modulating genes, so-called ''modifier genes'', have profound effects on the AhR-mediated gene expression phenotype. Based on the nucleotide sequence of the AhR coding region, the BALB/c, CBA/J, and C3H/He mouse strains are clustered together on a single branch. In the present study, we try to confirm the existence of modifiers by using microarray analysis to examine hepatic gene expression after TCDD exposure in BALB/c, CBA/J, and C3H/He mice. To recognize the existence of a modifier besides the AhR, it is a prerequisite experimental condition that the analyzed strains have an identical AhR genotype. Therefore, we selected BALB/c, CBA/J, and C3H/He mice as the model

  1. Nucleoli in large (giant bi- and multinucleate cells after apoptosis-inducing photodynamic treatment

    Directory of Open Access Journals (Sweden)

    K Smetana

    2009-06-01

    Full Text Available The present experimental study was undertaken to provide information on nucleolar changes accompanying the apoptotic process in large or giant binucleate and multinucleate cells (LBMNCs. Such cells were present in a small but constant percentage in cultures of HL-60 cells. The apoptotic process was induced by photodynamic treatment (PDT by means of 5-aminolaevulinic acid (ALA as the precursor of the photosensitizer protoporphyrin IX and irradiation with broad spectrum blue light (BL. Nucleolar changes in LBMNCs were characterized by marked reduction or disappearance of silver stained particles representing AgNORs in nucleoli including the large ones. In addition, PDT also significantly reduced the number of nucleoli regardless of their size. These changes apparently reflected the decrease or cessation of nucleolar biosynthetic activities and resembled those which were previously observed in naturally maturing bone marrow megakaryocytes (Janoutová et al., 2001.

  2. Method for determining correction factors induced by irradiation of ionization chamber cables in large radiation field

    International Nuclear Information System (INIS)

    Rodrigues, L.L.C.

    1988-01-01

    A simple method was developed to be suggested to hospital physicists in order to be followed during large radiation field dosimetry, to evaluate the effects of cables, connectors and extension cables irradiation and to determine correction factors for each system or geometry. All quality control tests were performed according to the International Electrotechnical Commission for three clinical dosimeters. Photon and electron irradiation effects for cables, connectors and extention cables were investigated under different experimental conditions by means of measurements of chamber sensitivity to a standard radiation source of 90 Sr. The radiation induced leakage current was also measured for cables, connectors and extension cables irradiated by photons and electrons. All measurements were performed at standard dosimetry conditions. Finally, measurements were performed in large fields. Cable factors and leakage factors were determined by the relation between chamber responses for irradiated and unirradiated cables. (author) [pt

  3. Maternal Obesity Induces Sustained Inflammation in Both Fetal and Offspring Large Intestine of Sheep

    Science.gov (United States)

    Yan, Xu; Huang, Yan; Wang, Hui; Du, Min; Hess, Bret W.; Ford, Stephen P.; Nathanielsz, Peter W.; Zhu, Mei-Jun

    2010-01-01

    Background Both maternal obesity and inflammatory bowel diseases (IBDs) are increasing. It was hypothesized that maternal obesity induces an inflammatory response in the fetal large intestine, predisposing offspring to IBDs. Methods Nonpregnant ewes were assigned to a control (Con, 100% of National Research Council [NRC] recommendations) or obesogenic (OB, 150% of NRC) diet from 60 days before conception. The large intestine was sampled from fetuses at 135 days (term 150 days) after conception and from offspring lambs at 22.5 ± 0.5 months of age. Results Maternal obesity enhanced mRNA expression tumor necrosis factor (TNF)α, interleukin (IL)1α, IL1β, IL6, IL8, and monocyte/macrophage chemotactic protein-1 (MCP1), as well as macrophage markers, CD11b, CD14, and CD68 in fetal gut. mRNA expression of Toll-like receptor (TLR) 2 and TLR4 was increased in OB versus Con fetuses; correspondingly, inflammatory NF-κB and JNK signaling pathways were also upregulated. Both mRNA expression and protein content of transforming growth factor (TGF) β was increased. The IL-17A mRNA expression and protein content was higher in OB compared to Con samples, which was associated with fibrosis in the large intestine of OB fetuses. Similar inflammatory responses and enhanced fibrosis were detected in OB compared to Con offspring. Conclusions Maternal obesity induced inflammation and enhanced expression of proinflammatory cytokines in fetal and offspring large intestine, which correlated with increased TGFβ and IL17 expression. These data show that maternal obesity may predispose offspring gut to IBDs. PMID:21674707

  4. Grape extract protects against γ-radiation-induced membrane damage strains of human erythrocytes

    International Nuclear Information System (INIS)

    Das, Subir Kumar

    2017-01-01

    The membrane integrity of circulating red blood cells (RBCs) is compromised by the deleterious actions of γ-radiation in humans. Grapes are the richest source of antioxidants due to presence of potentially bioactive phytochemicals. The objective of the present study was to assess the radioprotective actions of grape extracts against the γ-radiation-induced membrane permeability of human erythrocytes. The scavenging activities in seeds of grape in DPPH, hydrogen peroxide and hydroxyl radicals, were higher than skin or pulp of different cultivars. Grape extracts also showed appreciable extent of total antioxidant capacity and effective antihemolytic action. Grape extracts significantly ameliorated the γ-radiation-induced increase of the levels of thiobarbituric acid-reactive substances (TBARS, an index of lipid peroxidation) in the RBC membrane ghosts. Stored blood showed higher levels of K + ion as compared to the normal blood which was elevated by γ-radiation. Membrane ATPase was inhibited by the exposure to γ-radiation.Treatment of RBCs with the grape extracts prior to the exposure of γ-radiation significantly mitigated these changes in the erythrocyte membranes caused by the lower dose of radiation (4 Gy). (author)

  5. Stress, strain, and temperature induced permeability changes in potential repository rocks

    International Nuclear Information System (INIS)

    Heard, H.C.; Duba, A.

    1977-01-01

    Work is in progress to assess the permeability characteristics of coarse-grained igneous rocks as affected by pressure, deviatoric stress, and temperature. In order to predict the long-term behavior of these rocks, both virgin and fractured, permeability and all principal strains resulting from an imposed deviatoric stress under various simulated lithostatic pressures are being measured. In addition, compressional as well as shear velocities and electrical conductivity are being evaluated along these principal directions. These simultaneous measurements are being made initially at 25 0 C on a 15 cm diameter by 30 cm long sample in a pressure apparatus controlled by a mini-computer. Correlation of these data with similar field observations should then allow simplified exploration for a suitable repository site as well as the prediction of the response of a mined cavity with both distance and time at this site. After emplacement of the waste canisters, the mechanical stability and hydrologic integrity of this mined repository will be directly influenced by the fracturing of the surrounding rock which results from local temperature differences and the thermal expansion of that rock. Temperatures (and, hence, these differences) in the vicinity of the repository are expected to be affected by the presence of pore fluids (single- or two-phase) in the rock, the heat capacity and the thermal conductivity of this system. In turn, these are all dependent upon lithostatic pressure, pore pressure, and stress. Thermal expansion (and fracturing) will also be affected by the lithostatic (and effective) pressure, the deviatoric stress field, and the initial anisotropy of the rock

  6. Reversal of fluconazole resistance induced by a synergistic effect with Acca sellowiana in Candida glabrata strains.

    Science.gov (United States)

    R M Machado, Gabriella da; Pippi, Bruna; Dalla Lana, Daiane Flores; Amaral, Ana Paula S; Teixeira, Mário Lettieri; Souza, Kellen C B de; Fuentefria, Alexandre M

    2016-11-01

    The increased incidence of non-albicans Candida (NAC) resistant to fluconazole (FLZ) makes it necessary to use new therapeutic alternatives. Acca sellowiana (O.berg) Burret (Myrtaceae) is a guava with several proven biological activities. The interaction with fluconazole can be a feasible alternative to overcome this resistance. This study evaluates the in vitro antifungal activity of fractions obtained from the lyophilized aqueous extract of the leaves of A. sellowiana against resistant strains of NAC. The antifungal activity of the fractions was evaluated at 500 μg/mL by microdilution method. Checkerboard assay was performed to determine the effect of the combination of the F2 fraction and antifungal at concentrations: MIC/4, MIC/2, MIC, MIC × 2 and MIC × 4. Candida glabrata showed the lowest MIC values (500-3.90 μg/mL) and the F2 active fraction was the most effective. The association of F2 with FLZ showed a strong synergistic effect (FICI ≤ 0.5) against 100% of C. glabrata resistant isolates. Moreover, the F2 active fraction has demonstrated that probably acts in the cell wall of these yeasts. There was no observed acute dermal toxicity of lyophilized aqueous extract of leaves of A. sellowiana on pig ear skin cells. The interaction between substances present in the F2 active fraction is possibly responsible for the antifungal activity presented by this fraction. This study is unprecedented and suggests that the combination of F2 active fraction and FLZ might be used as an alternative treatment for mucocutaneus infections caused by C. glabrata resistant.

  7. Studies on radiation-induced thymic lymphomagenesis in B10 strain mice

    International Nuclear Information System (INIS)

    Muto, Masahiro

    1989-01-01

    Using B10.Thy 1 congenic strain mice, we reexamined the earlier results by Kaplan and others that lymphomas could develop from lymphocytes present in the nonirradiated parental thymuses grafted into thymectomized, fractionally irradiated H-2 semiincompatible recipient mice. The results indicated that 37 out of 91 thymectomized and irradiated B10.Thy 1.2 mice developed lymphomas of which 75 % were shown to have originated from grafted thymuses. The evidence was not obtained that supported the involvement of endogenous MuLV or some kind of transmissible agents during thymic lymphomagenesis. We found, with intrathymic injection assay, that 'preneoplastic' cells that will eventually develop into thymic lymphomas under the influence of thymic microenvironment first appeared in the thymuses about 4-8 days after irradiation. These thymic prelymphoma cells 'thymus-dependent' preneoplastic cells were detected in 26.1 % of the test donor thymuses when examined at 14 days and in more than 63 % 21 and 31 days after irradiation. It was found that lymphomagenic irradiation resulted in the anomalous appearance of CD4 + and/or CD8 + thymocytes bearing IL-2 receptor (IL-2R) which were different from normal thymocyte subpopulations. Thymic prelymphoma cells existed mainly in CD4 - CD8 - and CD4 - CD8 + thymocyted subpopulations and also in CD4 + CD8 + subpopulation. T cell lymphomas derived from CD4 - CD8 - prelymphoma cells had mainly CD4 - CD8 - or CD4 - CD8 + phenotypes. T cell lymphomas developed from CD4 - CD8 + prelymphoma cells mainly expressed CD4 - CD8 + or CD4 + CD8 + phenotype. T cell lymphomas originated from CD4 + CD8 + prelymphoma cells were mainly CD4 + CD8 + but some CD4 - CD8 + or CD4 + CD8 - cells were also present. These T cell lymphomas expressed IL-2R on various levels. The development of thymic prelymphoma cells is discussed in view of thymocyte differentiation. (J.P.N)

  8. Salt stress-induced transcription of σB- and CtsR-regulated genes in persistent and non-persistent Listeria monocytogenes strains from food processing plants.

    Science.gov (United States)

    Ringus, Daina L; Ivy, Reid A; Wiedmann, Martin; Boor, Kathryn J

    2012-03-01

    Listeria monocytogenes is a foodborne pathogen that can persist in food processing environments. Six persistent and six non-persistent strains from fish processing plants and one persistent strain from a meat plant were selected to determine if expression of genes in the regulons of two stress response regulators, σ(B) and CtsR, under salt stress conditions is associated with the ability of L. monocytogenes to persist in food processing environments. Subtype data were also used to categorize the strains into genetic lineages I or II. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to measure transcript levels for two σ(B)-regulated genes, inlA and gadD3, and two CtsR-regulated genes, lmo1138 and clpB, before and after (t=10 min) salt shock (i.e., exposure of exponential phase cells to BHI+6% NaCl for 10 min at 37°C). Exposure to salt stress induced higher transcript levels relative to levels under non-stress conditions for all four stress and virulence genes across all wildtype strains tested. Analysis of variance (ANOVA) of induction data revealed that transcript levels for one gene (clpB) were induced at significantly higher levels in non-persistent strains compared to persistent strains (p=0.020; two-way ANOVA). Significantly higher transcript levels of gadD3 (p=0.024; two-way ANOVA) and clpB (p=0.053; two-way ANOVA) were observed after salt shock in lineage I strains compared to lineage II strains. No clear association between stress gene transcript levels and persistence was detected. Our data are consistent with an emerging model that proposes that establishment of L. monocytogenes persistence in a specific environment occurs as a random, stochastic event, rather than as a consequence of specific bacterial strain characteristics.

  9. Inactive and mutagenic effects induced by carbon beams of different LET values in a red yeast strain

    International Nuclear Information System (INIS)

    Wang Jufang; Lu Dong; Wu Xin; Sun Haining; Ma Shuang; Li Renmin; Li Wenjian

    2010-01-01

    To evaluate biological action of microorganism exposed to charged particles during the long distance space exploration, induction of inactivation and mutation in a red yeast strain Rhodotorula glutinis AY 91015 by carbon beams of different LET values (14.9-120.0 keV μm -1 ) was investigated. It was found that survival curves were exponential, and mutation curves were linear for all LET values. The dependence of inactivation cross section on LET approached saturation near 120.0 keV μm -1 . The mutation cross section saturated when LET was higher than 58.2 keV μm -1 . Meanwhile, the highest RBE i for inactivation located at 120.0 keV μm -1 and the highest RBE m for mutation was at 58.2 keV μm -1 . The experiments imply that the most efficient mutagenic part of the depth dose profile of carbon ion is at the plateau region with intermediate LET value in which energy deposited is high enough to induce mutagenic lesions but too low to induce over kill effect in the yeast cells.

  10. Inactive and mutagenic effects induced by carbon beams of different LET values in a red yeast strain

    Science.gov (United States)

    Wang, Jufang; Lu, Dong; Wu, Xin; Sun, Haining; Ma, Shuang; Li, Renmin; Li, Wenjian

    2010-09-01

    To evaluate biological action of microorganism exposed to charged particles during the long distance space exploration, induction of inactivation and mutation in a red yeast strain Rhodotorula glutinis AY 91015 by carbon beams of different LET values (14.9-120.0 keV μm -1) was investigated. It was found that survival curves were exponential, and mutation curves were linear for all LET values. The dependence of inactivation cross section on LET approached saturation near 120.0 keV μm -1. The mutation cross section saturated when LET was higher than 58.2 keV μm -1. Meanwhile, the highest RBE i for inactivation located at 120.0 keV μm -1 and the highest RBE m for mutation was at 58.2 keV μm -1. The experiments imply that the most efficient mutagenic part of the depth dose profile of carbon ion is at the plateau region with intermediate LET value in which energy deposited is high enough to induce mutagenic lesions but too low to induce over kill effect in the yeast cells.

  11. Inactive and mutagenic effects induced by carbon beams of different LET values in a red yeast strain

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jufang, E-mail: jufangwang@impcas.ac.c [Institute of Modern Physics, Chinese Academy of Sciences, Nanchang Road No. 509, Lanzhou 730000 (China); Lu Dong; Wu Xin; Sun Haining; Ma Shuang; Li Renmin; Li Wenjian [Institute of Modern Physics, Chinese Academy of Sciences, Nanchang Road No. 509, Lanzhou 730000 (China)

    2010-09-15

    To evaluate biological action of microorganism exposed to charged particles during the long distance space exploration, induction of inactivation and mutation in a red yeast strain Rhodotorula glutinis AY 91015 by carbon beams of different LET values (14.9-120.0 keV {mu}m{sup -1}) was investigated. It was found that survival curves were exponential, and mutation curves were linear for all LET values. The dependence of inactivation cross section on LET approached saturation near 120.0 keV {mu}m{sup -1}. The mutation cross section saturated when LET was higher than 58.2 keV {mu}m{sup -1}. Meanwhile, the highest RBE{sub i} for inactivation located at 120.0 keV {mu}m{sup -1} and the highest RBE{sub m} for mutation was at 58.2 keV {mu}m{sup -1}. The experiments imply that the most efficient mutagenic part of the depth dose profile of carbon ion is at the plateau region with intermediate LET value in which energy deposited is high enough to induce mutagenic lesions but too low to induce over kill effect in the yeast cells.

  12. Effect of strain-induced martensitic transformation on high cycle fatigue behavior in cyclically-prestrained type 304

    International Nuclear Information System (INIS)

    Uematsu, Yoshihiko; Kakiuchi, Toshifumi; Akita, Masayuki; Nakajima, Masaki; Nakamura, Yuki; Yajima, Takumi

    2013-01-01

    The effects of the cyclic prestrain on the fatigue behavior in type 304 austenitic stainless steel were investigated. Rotating bending fatigue tests have been performed in laboratory air using the specimens subjected to ±5% cyclic prestrain at room temperature (R.T.) and -5°C. Martensitic phase volume fraction of the prestrained specimen at -5°C was 48% and larger than 3.8% at R.T. The prestrained specimens exhibited higher fatigue strengths than the as-received ones, and larger volume fraction of martensitic phase resulted in the higher fatigue limit. EBSD analysis revealed that the martensitic phases were more uniformly distributed in the austenitic matrix in the cyclically-prestrained specimens than in the monotonically-prestrained ones. Fatigue crack initiation from inclusion was observed only in the cyclically-prestrained specimens at -5°C. High volume fraction and uniform distribution of martensitic phase induced the transition of crack initiation mechanism and led to the higher fatigue limit. In type 304 stainless steel with high volume fraction of strain-induced martensitic phase, the prediction of fatigue limit based on Vickers hardness could give unconservative results. (author)

  13. Directed partial correlation: inferring large-scale gene regulatory network through induced topology disruptions.

    Directory of Open Access Journals (Sweden)

    Yinyin Yuan

    Full Text Available Inferring regulatory relationships among many genes based on their temporal variation in transcript abundance has been a popular research topic. Due to the nature of microarray experiments, classical tools for time series analysis lose power since the number of variables far exceeds the number of the samples. In this paper, we describe some of the existing multivariate inference techniques that are applicable to hundreds of variables and show the potential challenges for small-sample, large-scale data. We propose a directed partial correlation (DPC method as an efficient and effective solution to regulatory network inference using these data. Specifically for genomic data, the proposed method is designed to deal with large-scale datasets. It combines the efficiency of partial correlation for setting up network topology by testing conditional independence, and the concept of Granger causality to assess topology change with induced interruptions. The idea is that when a transcription factor is induced artificially within a gene network, the disruption of the network by the induction signifies a genes role in transcriptional regulation. The benchmarking results using GeneNetWeaver, the simulator for the DREAM challenges, provide strong evidence of the outstanding performance of the proposed DPC method. When applied to real biological data, the inferred starch metabolism network in Arabidopsis reveals many biologically meaningful network modules worthy of further investigation. These results collectively suggest DPC is a versatile tool for genomics research. The R package DPC is available for download (http://code.google.com/p/dpcnet/.

  14. Gravity-induced rock mass damage related to large en masse rockslides: Evidence from Vajont

    Science.gov (United States)

    Paronuzzi, Paolo; Bolla, Alberto

    2015-04-01

    The Vajont landslide is a well-known, reservoir-induced slope failure that occurred on 9 October 1963 and was characterized by an 'en masse' sliding motion that triggered various large waves, determining catastrophic consequences for the nearby territory and adjacent villages. During the Vajont dam construction, and especially after the disaster, some researchers identified widespread field evidence of heavy rock mass damage involving the presumed prehistoric rockslide and/or the 1963 failed mass. This paper describes evidence of heavy gravitational damage, including (i) folding, (ii) fracturing, (iii) faulting, and (iv) intact rock disintegration. The gravity-induced rock mass damage (GRMD) characterizes the remnants of the basal shear zone, still resting on the large detachment surface, and the 1963 failed rock mass. The comprehensive geological study of the 1963 Vajont landslide, based on the recently performed geomechanical survey (2006-present) and on the critical analysis of the past photographic documentation (1959-1964), allows us to recognize that most GRMD evidence is related to the prehistoric multistage Mt. Toc rockslide. The 1963 catastrophic en masse remobilization induced an increase to the prehistoric damage, reworking preexisting structures and creating additional gravity-driven features (folds, fractures, faults, and rock fragmentation). The gravity-induced damage was formed during the slope instability phases that preceded the collapse (static or quasi-static GRMD) and also as a consequence of the sliding motion and of the devastating impact between the failed blocks (dynamic GRMD). Gravitational damage originated various types of small drag folds such as flexures, concentric folds, chevron, and kink-box folds, all having a radius of 1-5 m. Large buckle folds (radius of 10-50 m) are related to the dynamic damage and were formed during the en masse motion as a consequence of deceleration and impact processes that involved the sliding mass. Prior

  15. Optical anisotropy induced by mechanical strain around the fundamental gap of GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Gallegos, J.; Lastras-Martinez, A.; Lastras-Martinez, L.F. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Balderas-Navarro, R.E. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Facultad de Ciencias, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)

    2008-07-01

    We report on a theoretical-experimental study of reflectance anisotropy spectroscopy (RAS) of GaAs (001) crystals under uniaxial stress. The study was carried out in the energy region around the fundamental transition. RAS spectra in the energy range from 1.2-1.7 eV were measured with a photoelastic-modulator-based spectrometer. To induce an optical anisotropy, the GaAs crystals were thinned down to 400 {mu}m and an calibrated uniaxial stress was applied by deflection. RAS showed a line shape consisting of an oscillation at around E{sub 0}. On the basis of a perturbative approach employing the Pikus-Bir Hamiltonian, we calculated the RAS line shape and found a close agreement with the experimental spectra. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Ferroelectric properties of Pb(Zr,Ti)O3 films under ion-beam induced strain

    Science.gov (United States)

    Lee, Jung-Kun; Nastasi, Michael

    2012-11-01

    The influence of an ion-beam induced biaxial stress on the ferroelectric and dielectric properties of Pb(Zr,Ti)O3 (PZT) films is investigated using the ion beam process as a novel approach to control external stress. Tensile stress is observed to decrease the polarization, permittivity, and ferroelectric fatigue resistance of the PZT films whose structure is monoclinic. However, a compressive stress increases all of them in monoclinic PZT films. The dependence of the permittivity on stress is found not to follow the phenomenological theory relating external forces to intrinsic properties of ferroelectric materials. Changes in the ferroelectric and dielectric properties indicate that the application of a biaxial stress modulates both extrinsic and intrinsic properties of PZT films. Different degrees of dielectric non-linearity suggests the density and mobility of non-180o domain walls, and the domain switching can be controlled by an applied biaxial stress and thereby influence the ferroelectric and dielectric properties.

  17. Prediction of thermal coagulation from the instantaneous strain distribution induced by high-intensity focused ultrasound

    Science.gov (United States)

    Iwasaki, Ryosuke; Takagi, Ryo; Tomiyasu, Kentaro; Yoshizawa, Shin; Umemura, Shin-ichiro

    2017-07-01

    The targeting of the ultrasound beam and the prediction of thermal lesion formation in advance are the requirements for monitoring high-intensity focused ultrasound (HIFU) treatment with safety and reproducibility. To visualize the HIFU focal zone, we utilized an acoustic radiation force impulse (ARFI) imaging-based method. After inducing displacements inside tissues with pulsed HIFU called the push pulse exposure, the distribution of axial displacements started expanding and moving. To acquire RF data immediately after and during the HIFU push pulse exposure to improve prediction accuracy, we attempted methods using extrapolation estimation and applying HIFU noise elimination. The distributions going back in the time domain from the end of push pulse exposure are in good agreement with tissue coagulation at the center. The results suggest that the proposed focal zone visualization employing pulsed HIFU entailing the high-speed ARFI imaging method is useful for the prediction of thermal coagulation in advance.

  18. Nanoscale strain-induced pair suppression as a vortex-pinning mechanism in high-temperature superconductors

    International Nuclear Information System (INIS)

    Llordes, Anna; Palau, A.; Gazquez, J.; Coll, M.; Vlad, R.; Pomar, A.; Arbiol, Jordi; Guzman, Roger; Ye, S.; Rouco, V.; Sandiumenge, Felip; Ricart, Susagna; Puig, Teresa; Varela del Arco, Maria; Chataigner, D.; Vanacken, J.; Gutierrez, J.; Moschalkov, V.; Deutscher, G.; Magen Dominguez, Cesar; Obradors, Xavier

    2012-01-01

    Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centers in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa 2 Cu 3 O 7 matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.

  19. Mycobacterium tuberculosis strains exhibit differential and strain-specific molecular signatures in pulmonary epithelial cells.

    Science.gov (United States)

    Mvubu, Nontobeko Eunice; Pillay, Balakrishna; Gamieldien, Junaid; Bishai, William; Pillay, Manormoney

    2016-12-01

    Although pulmonary epithelial cells are integral to innate and adaptive immune responses during Mycobacterium tuberculosis infection, global transcriptomic changes in these cells remain largely unknown. Changes in gene expression induced in pulmonary epithelial cells infected with M. tuberculosis F15/LAM4/KZN, F11, F28, Beijing and Unique genotypes were investigated by RNA sequencing (RNA-Seq). The Illumina HiSeq 2000 platform generated 50 bp reads that were mapped to the human genome (Hg19) using Tophat (2.0.10). Differential gene expression induced by the different strains in infected relative to the uninfected cells was quantified and compared using Cufflinks (2.1.0) and MeV (4.0.9), respectively. Gene expression varied among the strains with the total number of genes as follows: F15/LAM4/KZN (1187), Beijing (1252), F11 (1639), F28 (870), Unique (886) and H37Rv (1179). A subset of 292 genes was commonly induced by all strains, where 52 genes were down-regulated while 240 genes were up-regulated. Differentially expressed genes were compared among the strains and the number of induced strain-specific gene signatures were as follows: F15/LAM4/KZN (138), Beijing (52), F11 (255), F28 (55), Unique (186) and H37Rv (125). Strain-specific molecular gene signatures associated with functional pathways were observed only for the Unique and H37Rv strains while certain biological functions may be associated with other strain signatures. This study demonstrated that strains of M. tuberculosis induce differential gene expression and strain-specific molecular signatures in pulmonary epithelial cells. Specific signatures induced by clinical strains of M. tuberculosis can be further explored for novel host-associated biomarkers and adjunctive immunotherapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Characterization of recombinant B. abortus strain RB51SOD towards understanding the uncorrelated innate and adaptive immune responses induced by RB51SOD compared to its parent vaccine strain RB51

    Directory of Open Access Journals (Sweden)

    Jianguo eZhu

    2011-11-01

    Full Text Available Brucella abortus is a Gram-negative, facultative intracellular pathogen for several mammals, including humans. Live attenuated B. abortus strain RB51 is currently the official vaccine used against bovine brucellosis in the United States and several other countries. Overexpression of protective B. abortus antigen Cu/Zn superoxide dismutase (SOD in a recombinant strain of RB51 (strain RB51SOD significantly increases its vaccine efficacy against virulent B. abortus challenge in a mouse model. An attempt has been made to better understand the mechanism of the enhanced protective immunity of RB51SOD compared to its parent strain RB51. We previously reported that RB51SOD stimulated enhanced Th1 immune response. In this study, we further found that T effector cells derived from RB51SOD-immunized mice exhibited significantly higher cytotoxic T lymphocyte (CTL activity than T effector cells derived from RB51-immunized mice against virulent B. abortus-infected target cells. Meanwhile, the macrophage responses to these two strains were also studied. Compared to RB51, RB51SOD cells had a lower survival rate in macrophages and induced lower levels of macrophage apoptosis and necrosis. The decreased survival of RB51SOD cells correlates with the higher sensitivity of RB51SOD, compared to RB51, to the bactericidal action of either Polymyxin B or sodium dodecyl sulfate (SDS. Furthermore, a physical damage to the outer membrane of RB51SOD was observed by electron microscopy. Possibly due to the physical damage, overexpressed Cu/Zn SOD in RB51SOD was found to be released into the bacterial cell culture medium. Therefore, the stronger adaptive immunity induced by RB51SOD did not correlate with the low level of innate immunity induced by RB51SOD compared to RB51. This unique and apparently contradictory profile is likely associated with the differences in outer membrane integrity and Cu/Zn SOD release.

  1. Salmonella Typhimurium induces SPI-1 and SPI-2 regulated and strain dependent downregulation of MHC II expression on porcine alveolar macrophages

    Directory of Open Access Journals (Sweden)

    Van Parys Alexander

    2012-06-01

    Full Text Available Abstract Foodborne salmonellosis is one of the most important bacterial zoonotic diseases worldwide. Salmonella Typhimurium is the serovar most frequently isolated from persistently infected slaughter pigs in Europe. Circumvention of the host’s immune system by Salmonella might contribute to persistent infection of pigs. In the present study, we found that Salmonella Typhimurium strain 112910a specifically downregulated MHC II, but not MHC I, expression on porcine alveolar macrophages in a Salmonella pathogenicity island (SPI-1 and SPI-2 dependent way. Salmonella induced downregulation of MHC II expression and intracellular proliferation of Salmonella in macrophages were significantly impaired after opsonization with Salmonella specific antibodies prior to inoculation. Furthermore, the capacity to downregulate MHC II expression on macrophages differed significantly among Salmonella strains, independently of strain specific differences in invasion capacity, Salmonella induced cytotoxicity and altered macrophage activation status. The fact that strain specific differences in MHC II downregulation did not correlate with the extent of in vitro SPI-1 or SPI-2 gene expression indicates that other factors are involved in MHC II downregulation as well. Since Salmonella strain dependent interference with the pig’s immune response through downregulation of MHC II expression might indicate that certain Salmonella strains are more likely to escape serological detection, our findings are of major interest for Salmonella monitoring programs primarily based on serology.

  2. Microbially induced selective flotation of sphalerite from galena using mineral-adapted strains of Bacillus megaterium.

    Science.gov (United States)

    Vasanthakumar, B; Ravishankar, H; Subramanian, S

    2013-12-01

    The selective flotation of sphalerite from a sphalerite-galena mineral mixture has been achieved using cells and extracellular secretions of Bacillus megaterium after adaptation to the chosen minerals. The extracellular secretions obtained after thermolysis of bacterial cells adapted to sphalerite yield the highest flotation recovery of sphalerite with a selectivity index value of 24.5, in comparison to the other cellular and extra-cellular bio-reagents studied. The protein profile for the unadapted and mineral-adapted cells has been found to differ distinctly, attesting to variation in the yield and nature of extra-cellular polymeric substances (EPS). The changes induced in the bacterial cell wall components after adaptation to sphalerite or galena with respect to the contents of phosphate, uronic acid and acetylated sugars of B. megaterium have been quantified. The role of the dissolved metal ions from the minerals as well as that of the constituents of extracellular secretions in modulating the surface charge of the bacterial cells as well as the minerals under study has been confirmed using various enzymatic treatments of the bacterial cells. It has been demonstrated that the induction of additional molecular weight protein fractions as well as the higher amount of extracellular proteins and phosphate secreted after adaptation to sphalerite vis-à-vis galena are contributory factors for the selective separation of sphalerite from galena. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Lactobacillus rhamnosus strain JB-1 reverses restraint stress-induced gut dysmotility.

    Science.gov (United States)

    West, C; Wu, R Y; Wong, A; Stanisz, A M; Yan, R; Min, K K; Pasyk, M; McVey Neufeld, K-A; Karamat, M I; Foster, J A; Bienenstock, J; Forsythe, P; Kunze, W A

    2017-01-01

    Environmental stress affects the gut with dysmotility being a common consequence. Although a variety of microbes or molecules may prevent the dysmotility, none reverse the dysmotility. We have used a 1 hour restraint stress mouse model to test for treatment effects of the neuroactive microbe, L. rhamnosus JB-1 ™ . Motility of fluid-filled ex vivo gut segments in a perfusion organ bath was recorded by video and migrating motor complexes measured using spatiotemporal maps of diameter changes. Stress reduced jejunal and increased colonic propagating contractile cluster velocities and frequencies, while increasing contraction amplitudes for both. Luminal application of 10E8 cfu/mL JB-1 restored motor complex variables to unstressed levels within minutes of application. L. salivarius or Na.acetate had no treatment effects, while Na.butyrate partially reversed stress effects on colonic frequency and amplitude. Na.propionate reversed the stress effects for jejunum and colon except on jejunal amplitude. Our findings demonstrate, for the first time, a potential for certain beneficial microbes as treatment of stress-induced intestinal dysmotility and that the mechanism for restoration of function occurs within the intestine via a rapid drug-like action on the enteric nervous system. © 2016 John Wiley & Sons Ltd.

  4. Constitutive modelling and identification of parameters of the plastic strain-induced martensitic transformation in 316L stainless steel at cryogenic temperatures

    CERN Document Server

    Garion, C; Sgobba, Stefano

    2006-01-01

    The present paper is focused on constitutive modelling and identification of parameters of the relevant model of plastic strain- induced martensitic transformation in austenitic stainless steels at low temperatures. The model used to describe the FCCrightward arrow BCC phase transformation in austenitic stainless steels is based on the assumption of linearization of the most intensive part of the transformation curve. The kinetics of phase transformation is described by three parameters: transformation threshold (p/sub xi/), slope (A) and saturation level (xi/sub L/). It is assumed that the phase transformation is driven by the accumulated plastic strain p. In addition, the intensity of plastic deformation is strongly coupled to the phase transformation via the description of mixed kinematic /isotropic linear plastic hardening based on the Mori-Tanaka homogenization. The theory of small strains is applied. Small strain fields, corresponding to phase transformation, are decomposed into the volumic and the shea...

  5. Recovery from ultraviolet light-induced inhibition of DNA synthesis requires umuDC gene products in recA718 mutant strains but not in recA+ strains of Escherichia coli

    International Nuclear Information System (INIS)

    Witkin, E.M.; Roegner-Maniscalco, V.; Sweasy, J.B.; McCall, J.O.

    1987-01-01

    Ultraviolet light (UV) inhibits DNA replication in Eschericia coli and induces the SOS response, a set of survival-enhancing phenotypes due to derepression of DNA damage-inducible genes, including recA and umuDC. Recovery of DNA synthesis after UV irradiation (induced replisome reactivation, or IRR) is an SOS function requiring RecA protein and postirradiation synthesis of additional protein(s), but this recovery does not require UmuDC protein. IRR occurs in strains carrying either recA718 (which does not reduce recombination, SOS inducibility, or UV mutagenesis) or umuC36 (which eliminates UV mutability), but not in recA718 umuC36 double mutants. In recA430 mutant strains, IRR does not occur whether or not functional UmuDC protein is present. IRR occurs in lexA-(Ind-) (SOS noninducible) strains if they carry an operator-constitutive recA allele and are allowed to synthesize proteins after irradiation. We conclude the following: (i) that UmuDC protein corrects or complements a defect in the ability of RecA718 protein (but not of RecA430 protein) to promote IRR and (ii) that in lexA(Ind-) mutant strains, IRR requires amplification of RecA+ protein (but not of any other LexA-repressed protein) plus post-UV synthesis of at least one other protein not controlled by LexA protein. We discuss the results in relation to the essential, but unidentified, roles of RecA and UmuDC proteins in UV mutagenesis

  6. On strain-induced dissolution of θ' and θ particles in Al-Cu binary alloy during equal channel angular pressing

    International Nuclear Information System (INIS)

    Liu Zhiyi; Bai Song; Zhou Xuanwei; Gu Yanxia

    2011-01-01

    Research highlights: → θ' particles in Al-Cu binary alloy was found to dissolve more rapidly than θ particles. → The different dissolution behavior of the θ' and θ phase was thermodynamically analysed. → The critical radius and free energy barrier for the strain-induced dissolution were calculated. - Abstract: The deformable θ' particle in Al-Cu binary alloy was found to dissolve more rapidly than the indeformable θ particle due to an additional increasing strain energy accumulated in the deformed θ' plate as well as an increasing interface energy led by the formation of sub-boundary in the θ' plate and fragmentation of the particle during equal channel angular pressing (ECAP). The critical radius and the free energy barrier for the strain-induced dissolution of both θ' and θ particles were calculated.

  7. New Insights into the Relationship Between Network Structure and Strain Induced Crystallization in Unvolcanized Natural Rubber by Synchrotron X-ray Diffraction

    International Nuclear Information System (INIS)

    Toki, S.; Hsiao, B.; Amnuaypornsri, S.; Sakdapipanich, J.

    2009-01-01

    The relationship between the network structure and strain-induced crystallization in un-vulcanized as well as vulcanized natural rubbers (NR) and synthetic poly-isoprene rubbers (IR) was investigated via synchrotron wide-angle X-ray diffraction (WAXD) technique. It was found that the presence of a naturally occurring network structure formed by natural components in un-vulcanized NR significantly facilitates strain-induced crystallization and enhances modulus and tensile strength. The stress-strain relation in vulcanized NR is due to the combined effect of chemical and naturally occurring networks. The weakness of naturally occurring network against stress and temperature suggests that vulcanized NR has additional relaxation mechanism due to naturally occurring network. The superior mechanical properties in NR compared with IR are mainly due to the existence of naturally occurring network structure.

  8. Strain-induced enhancement of thermoelectric performance of TiS2 monolayer based on first-principles phonon and electron band structures

    Science.gov (United States)

    Li, Guanpeng; Yao, Kailun; Gao, Guoying

    2018-01-01

    Using first-principle calculations combined with Boltzmann transport theory, we investigate the biaxial strain effect on the electronic and phonon thermal transport properties of a 1 T (CdI2-type) structural TiS2 monolayer, a recent experimental two-dimensional (2D) material. It is found that the electronic band structure can be effectively modulated and that the band gap experiences an indirect-direct-indirect transition with increasing tensile strain. The band convergence induced by the tensile strain increases the Seebeck coefficient and the power factor, while the lattice thermal conductivity is decreased under the tensile strain due to the decreasing group velocity and the increasing scattering chances between the acoustic phonon modes and the optical phonon modes, which together greatly increase the thermoelectric performance. The figure of merit can reach 0.95 (0.82) at an 8 percent tensile strain for the p-type (n-type) doping, which is much larger than that without strain. The present work suggests that the TiS2 monolayer is a good candidate for 2D thermoelectric materials, and that biaxial strain is a powerful tool with which to enhance thermoelectric performance.

  9. Soil microbial species loss affects plant biomass and survival of an introduced bacterial strain, but not inducible plant defences.

    Science.gov (United States)

    Kurm, Viola; van der Putten, Wim H; Pineda, Ana; Hol, W H Gera

    2018-02-12

    Plant growth-promoting rhizobacteria (PGPR) strains can influence plant-insect interactions. However, little is known about the effect of changes in the soil bacterial community in general and especially the loss of rare soil microbes on these interactions. Here, the influence of rare soil microbe reduction on induced systemic resistance (ISR) in a wild ecotype of Arabidopsis thaliana against the aphid Myzus persicae was investigated. To create a gradient of microbial abundances, soil was inoculated with a serial dilution of a microbial community and responses of Arabidopsis plants that originated from the same site as the soil microbes were tested. Plant biomass, transcription of genes involved in plant defences, and insect performance were measured. In addition, the effects of the PGPR strain Pseudomonas fluorescens SS101 on plant and insect performance were tested under the influence of the various soil dilution treatments. Plant biomass showed a hump-shaped relationship with soil microbial community dilution, independent of aphid or Pseudomonas treatments. Both aphid infestation and inoculation with Pseudomonas reduced plant biomass, and led to downregulation of PR1 (salicylic acid-responsive gene) and CYP79B3 (involved in synthesis of glucosinolates). Aphid performance and gene transcription were unaffected by soil dilution. Neither the loss of rare microbial species, as caused by soil dilution, nor Pseudomonas affect the resistance of A. thaliana against M. persicae. However, both Pseudomonas survival and plant biomass respond to rare species loss. Thus, loss of rare soil microbial species can have a significant impact on both above- and below-ground organisms. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Red to green emitters from InGaP/InAlGaP laser structure by strain-induced quantum-well intermixing

    KAUST Repository

    Al-Jabr, Ahmad; Majid, Mohammed Abdul; Shen, Chao; Ng, Tien Khee; Ooi, Boon S.

    2016-01-01

    We increased the Al content in the single quantum well InGaP/InAlGaP laser by strain-induced quantum well intermixing, and obtained a considerable enhancement (close to ten-fold increase) in the photoluminescence (PL) intensity. Among the annealing

  11. Bacterial Polymertropism, the Response to Strain-Induced Alignment of Polymers

    Science.gov (United States)

    Lemon, David J.

    In nature, bacteria often live in surface-associated communities known as biofilms. Biofilm-forming bacteria deposit a layer of polysaccharide on the surfaces they inhabit; hence, polysaccharide is their immediate environment on any surface. In this study, we examined how the physical characteristics of polysaccharide substrates influence the behavior of the biofilm-forming bacterium Myxococcus xanthus. M. xanthus colonies, and indeed those of the majority of biofilm-forming species tested, respond to the compression-induced deformation of polysaccharide substrates by preferentially spreading across the surface perpendicular to the axis of compression. This response is conserved across multiple distantly related phyla and is found in species with an array of distinct motility apparatuses.The birefringence and small angle X-ray scattering patterns of compressed polysaccharide substrates indicate that the directed surface movements of these bacteria consistently match the orientation of the long axes of aligned and tightly packed polysaccharide fibers in compressed substrates. Therefore, we refer to this behavior as polymertropism to denote that the directed movements are a response to the physical arrangement of the change in packing and alignment of the polymers in the substrate. In addition to altering the colony morphology we find the behavior of groups of cells, called flares, is also affected in several species resulting in increased flare speed, duration, and displacement on compressed gel substrates.We suggest that polymertropism, which requires a downward-facing motility apparatus in M. xanthus, may be responsible for the observed tendency of bacterial cells to follow trails of extruded and presumably aligned polysaccharides, which their neighbors secrete and deposit on the substrate as they move across it. Polymertropism may also play a role in the organization of bacteria in a biofilm, as the iterative process of polysaccharide trail deposition and

  12. Listeria monocytogenes strains show large variations in competitive growth in mixed culture biofilms and suspensions with bacteria from food processing environments.

    Science.gov (United States)

    Heir, Even; Møretrø, Trond; Simensen, Andreas; Langsrud, Solveig

    2018-06-20

    Interactions and competition between resident bacteria in food processing environments could affect their ability to survive, grow and persist in microhabitats and niches in the food industry. In this study, the competitive ability of L. monocytogenes strains grown together in separate culture mixes with other L. monocytogenes (L. mono mix), L. innocua (Listeria mix), Gram-negative bacteria (Gram- mix) and with a multigenera mix (Listeria + Gram- mix) was investigated in biofilms on stainless steel and in suspensions at 12 °C. The mixed cultures included resident bacteria from processing surfaces in meat and salmon industry represented by L. monocytogenes (n = 6), L. innocua (n = 5) and Gram-negative bacteria (n = 6; Acinetobacter sp., Pseudomonas fragi, Pseudomonas fluorescens, Serratia liquefaciens, Stenotrophomonas maltophilia). Despite hampered in growth in mixed cultures, L. monocytogenes established in biofilms with counts at day nine between 7.3 and 9.0 log per coupon with the lowest counts in the Listeria + G- mix that was dominated by Pseudomonas. Specific L. innocua inhibited growth of L. monocytogenes strains differently; inhibition that was further enhanced by the background Gram-negative microbiota. In these multispecies and multibacteria cultures, the growth competitive effects lead to the dominance of a strong competitor L. monocytogenes strain that was only slightly inhibited by L. innocua and showed strong competitive abilities in mixed cultures with resident Gram-negative bacteria. The results indicates complex patterns of bacterial interactions and L. monocytogenes inhibition in the multibacteria cultures that only partially depend on cell contact and likely involve various antagonistic and bacterial tolerance mechanisms. The study indicates large variations among L. monocytogenes in their competitiveness under multibacterial culture conditions that should be considered in further studies towards understanding of L

  13. The role of enterovirus 71 and coxsackievirus A strains in a large outbreak of hand, foot, and mouth disease in 2012 in Changsha, China.

    Science.gov (United States)

    Chen, Jing-Fang; Zhang, Ru-Sheng; Ou, Xin-Hua; Chen, Fa-Ming; Sun, Bian-Cheng

    2014-11-01

    During 2012, Changsha experienced a large outbreak of hand, foot, and mouth disease (HFMD), resulting in 25,438 cases, including 42 severe cases and eight deaths. Seven hundred and forty-six clinical specimens were collected from hospital-based surveillance for HFMD in 2012. The detection and genotyping of enterovirus were performed by real-time RT-PCR and sequencing of the VP1 regions; phylogenetic analysis was performed based on the VP1 sequences. A total of 545 (73.1%) enterovirus-positive samples were identified, with the most frequently presenting serotype being enterovirus 71 (EV-71; n=364, 66.8%), followed by coxsackievirus A16 (CV-A16; n=84, 15.4%), CV-A6 (n=22, 4.0%), and CV-A10 (n=19, 3.5%). Most of the affected patients were children aged ≤5 years (n=524, 96.1%). EV-71 was the major pathogen in the severe and fatal cases (n=22, 78.6%). Phylogenetic analysis of VP1 gene sequences showed the EV-71 isolates to belong to subgenotype C4a, and the CV-A16 isolates to belong to subgenotype B1. The Changsha CV-A6 and CV-A10 circulating strains were homologous to strains circulating in other areas of mainland China. Our results demonstrate that EV-71 was the primary causative agent responsible for the HFMD outbreak in Changsha in 2012, and the co-circulation of other coxsackievirus A strains posed a potential risk to public health.

  14. Virulent and avirulent strains of equine arteritis virus induce different quantities of TNF-α and other proinflammatory cytokines in alveolar and blood-derived equine macrophages

    International Nuclear Information System (INIS)

    Moore, Brian D.; Balasuriya, Udeni B.R.; Watson, Johanna L.; Bosio, Catharine M.; MacKay, Robert J.; MacLachlan, N. James

    2003-01-01

    Equine arteritis virus (EAV) infects endothelial cells (ECs) and macrophages in horses, and many of the clinical manifestations of equine viral arteritis (EVA) reflect vascular injury. To further evaluate the potential role of EAV-induced, macrophage-derived cytokines in the pathogenesis of EVA, we infected cultured equine alveolar macrophages (AMphi), blood monocyte-derived macrophages (BMphi), and pulmonary artery ECs with either a virulent (KY84) or an avirulent (CA95) strain of EAV. EAV infection of equine AMphi, BMphi, and ECs resulted in their activation with increased transcription of genes encoding proinflammatory mediators, including interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α. Furthermore, the virulent KY84 strain of EAV induced significantly higher levels of mRNA encoding proinflammatory cytokines in infected AMphi and BMphi than did the avirulent CA95 strain. Treatment of equine ECs with the culture supernatants of EAV-infected AMphi and BMphi also resulted in EC activation with cell surface expression of E-selectin, whereas infection of ECs with purified EAV alone caused only minimal expression of E-selectin. The presence of TNF-α in the culture supernatants of EAV-infected equine AMphi, BMphi, and ECs was confirmed by bioassay, and the virulent KY84 strain of EAV induced significantly more TNF-α in all cell types than did the avirulent CA95 strain. Thus, the data indicate that EAV-induced, macrophage-derived cytokines may contribute to the pathogenesis of EVA in horses, and that the magnitude of the cytokine response of equine AMphi, BMphi, and ECs to EAV infection reflects the virulence of the infecting virus strain

  15. Strain-Induced Rolled Thin Films for Lightweight Tubular Thermoelectric Generators

    KAUST Repository

    Singh, Devendra

    2017-11-24

    Thermoelectric generators (TEGs) are interesting energy harvesters of otherwise wasted heat. Here, a polymer-assisted generic process and its mechanics to obtain sputtered thermoelectric (TE) telluride material-based 3D tubular structures with unprecedented length (up to seamless 4 cm and further expandable) are shown. This length allows for large temperature differences between the hot and the cold ends, a critical but untapped enabler for high power generation. Compared with a flat slab, better area efficiency is observed for a rolled tube and compared with a solid rod architecture, a rolled tube uses less material (thus making it lightweight and cost effective) and has competitive performance advantage due to a smaller contact area. It is also shown that a tubular architecture thermopile-based TEG is able to generate up to 5 μW of power (eight pairs of p- and n-type thermopiles) through a temperature difference of 60 °C. The demonstrated process can play an important role in transforming 2D atomic crystal structure TE materials into 3D tubular thermopiles for effective TEG application, which can maintain higher temperature differences by longer distances between hot and cold ends.

  16. Job strain, effort-reward imbalance and employee well-being: a large-scale cross-sectional study.

    Science.gov (United States)

    de Jonge, J; Bosma, H; Peter, R; Siegrist, J

    2000-05-01

    This study investigated the effects of the Job Demand-Control (JD-C) Model and the Effort-Reward Imbalance (ERI) Model on employee well-being. A cross-sectional survey was conducted comprising a large representative sample of 11,636 employed Dutch men and women. Logistic regression analyses were used. Controlling for job sector, demographic characteristics (including educational level) and managerial position, employees reporting high job demands (i.e. psychological and physical demands) and low job control had elevated risks of emotional exhaustion, psychosomatic and physical health complaints and job dissatisfaction (odds ratios ranged from 2.89 to 10.94). Odds ratios were generally higher in employees reporting both high (psychological and physical) efforts and low rewards (i.e. poor salary, job insecurity and low work support): they ranged from 3.23 to 15.43. Furthermore, overcommitted people had higher risks of poor well-being due to a high effort-low reward mismatch (ORs: 3.57-20.81) than their less committed counterparts (ORs: 3.01-12.71). Finally, high efforts and low occupational rewards were stronger predictors of poor well-being than low job control when both job stress models were simultaneously adjusted. In conclusion, our findings show independent cumulative effects of both the JD-C Model and the ERI Model on employee well-being and are not significantly different in men and women as well as in young and old people. In particular, high (psychological and physical) efforts and low rewards adversely affected employee well-being. Preliminary findings also indicate excess risks of poor well-being in overcommitted persons suffering from high cost--low gain conditions at work.

  17. A Cyanide-Induced 3-Cyanoalanine Nitrilase in the Cyanide-Assimilating Bacterium Pseudomonas pseudoalcaligenes Strain CECT 5344.

    Science.gov (United States)

    Acera, Felipe; Carmona, María Isabel; Castillo, Francisco; Quesada, Alberto; Blasco, Rafael

    2017-05-01

    Pseudomonas pseudoalcaligenes CECT 5344 is a bacterium able to assimilate cyanide as a sole nitrogen source. Under this growth condition, a 3-cyanoalanine nitrilase enzymatic activity was induced. This activity was encoded by nit4 , one of the four nitrilase genes detected in the genome of this bacterium, and its expression in Escherichia coli enabled the recombinant strain to fully assimilate 3-cyanoalanine. P. pseudoalcaligenes CECT 5344 showed a weak growth level with 3-cyanoalanine as the N source, unless KCN was also added. Moreover, a nit4 knockout mutant of P. pseudoalcaligenes CECT 5344 became severely impaired in its ability to grow with 3-cyanoalanine and cyanide as nitrogen sources. The native enzyme expressed in E. coli was purified up to electrophoretic homogeneity and biochemically characterized. Nit4 seems to be specific for 3-cyanoalanine, and the amount of ammonium derived from the enzymatic activity doubled in the presence of exogenously added asparaginase activity, which demonstrated that the Nit4 enzyme had both 3-cyanoalanine nitrilase and hydratase activities. The nit4 gene is located downstream of the cyanide resistance transcriptional unit containing cio1 genes, whose expression levels are under the positive control of cyanide. Real-time PCR experiments revealed that nit4 expression was also positively regulated by cyanide in both minimal and LB media. These results suggest that this gene cluster including cio1 and nit4 could be involved both in cyanide resistance and in its assimilation by P. pseudoalcaligenes CECT 5344. IMPORTANCE Cyanide is a highly toxic molecule present in some industrial wastes due to its application in several manufacturing processes, such as gold mining and the electroplating industry. The biodegradation of cyanide from contaminated wastes could be an attractive alternative to physicochemical treatment. P. pseudoalcaligenes CECT 5344 is a bacterial strain able to assimilate cyanide under alkaline conditions, thus

  18. Development of an Evaluation Methodology for Loss of Large Area induced from extreme events

    International Nuclear Information System (INIS)

    Kim, Sok Chul; Park, Jong Seuk; Kim, Byung Soon; Jang, Dong Ju; Lee, Seung Woo

    2015-01-01

    USNRC announced several regulatory requirements and guidance documents regarding the event of loss of large area including 10CFR 50.54(hh), Regulatory Guide 1.214 and SRP 19.4. In Korea, consideration of loss of large area has been limitedly taken into account for newly constructing NPPs as voluntary based. In general, it is hardly possible to find available information on methodology and key assumptions for the assessment of LOLA due to 'need to know based approach'. Urgent needs exists for developing country specific regulatory requirements, guidance and evaluation methodology by themselves with the consideration of their own geographical and nuclear safety and security environments. Currently, Korea Hydro and Nuclear Power Company (KHNP) has developed an Extended Damage Mitigation Guideline (EDMG) for APR1400 under contract with foreign consulting company. The submittal guidance NEI 06-12 related to B.5.b Phase 2 and 3 focused on unit-wise mitigation strategy instead of site level mitigation or response strategy. Phase 1 mitigating strategy and guideline for LOLA (Loss of Large Area) provides emphasis on site level arrangement including cooperative networking outside organizations and agile command and control system. Korea Institute of Nuclear Safety has carried out a pilot in-house research project to develop the methodology and guideline for evaluation of LOLA since 2014. This paper introduces the summary of major results and outcomes of the aforementioned research project. After Fukushima Dai-Ichi accident, the awareness on countering the event of loss of large area induced from extreme man-made hazards or extreme beyond design basis external event. Urgent need exists to develop regulatory guidance for coping with this undesirable situation, which has been out of consideration at existing nuclear safety regulatory framework due to the expectation of rare possibility of occurrence

  19. Rb-Sr dating of strain-induced mineral growth in two ductile shear zones in the western gneiss region of Nord-Troendelag, Central Norway

    International Nuclear Information System (INIS)

    Piasecki, M.A.; Cliff, R.A.

    1988-01-01

    In the Bjugn district of the northern part of the Western Gneiss Region, Nord-Troendelag, a basement gneiss-cover nappe boundary is marked by a thick zone of ductile shearing. In this zone a layer-parallel mylonitic fabric with related new mineral growth overprints and retrogresses a previous fabric associated with a granulite facies mineral assemblage. Related minor shear belts contain abundant new minerals and vein systems, including pegmatites, believed to represent strain-induced products formed at the time of the shearing movements. Central parts of two large muscovite books from such a pegmatite yielded Rb-Sr, Early to Middle Devonian ages of 389±6 Ma and 386±6 Ma, interpreted as indicating the approximate time of pegmatite formation and of the shearing. Small, matrix-size muscovite and biotite grains from the host mylonite gave ages of 378±6 Ma and 365±5 Ma, respectively, supposed to relate to post-shearing uplift and cooling

  20. Study on severe accident induced by large break loss of coolant accident for pressureized water reactor

    International Nuclear Information System (INIS)

    Zhang Longfei; Zhang Dafa; Wang Shaoming

    2007-01-01

    Using the best estimate computer code SCDAP/RELAP5/MOD3.2 and taking US Westinghouse corporation Surry nuclear power plant as the reference object, a typical three-loop pressurized water reactor severe accident calculation model was established and 25 cm large break loss of coolant accident (LBLOCA) in cold and hot leg of primary loop induced core melt accident was analyzed. The calculated results show that core melt progression is fast and most of the core material melt and relocated to the lower plenum. The lower head of reactor pressure vessel failed at an early time and the cold leg break is more severe than the hot leg break in primary loop during LBLOCA. (authors)

  1. Large Fizeau's light-dragging effect in a moving electromagnetically induced transparent medium.

    Science.gov (United States)

    Kuan, Pei-Chen; Huang, Chang; Chan, Wei Sheng; Kosen, Sandoko; Lan, Shau-Yu

    2016-10-03

    As one of the most influential experiments on the development of modern macroscopic theory from Newtonian mechanics to Einstein's special theory of relativity, the phenomenon of light dragging in a moving medium has been discussed and observed extensively in different types of systems. To have a significant dragging effect, the long duration of light travelling in the medium is preferred. Here we demonstrate a light-dragging experiment in an electromagnetically induced transparent cold atomic ensemble and enhance the dragging effect by at least three orders of magnitude compared with the previous experiments. With a large enhancement of the dragging effect, we realize an atom-based velocimeter that has a sensitivity two orders of magnitude higher than the velocity width of the atomic medium used. Such a demonstration could pave the way for motional sensing using the collective state of atoms in a room temperature vapour cell or solid state material.

  2. Extreme value prediction of the wave-induced vertical bending moment in large container ships

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

    2015-01-01

    increase the extreme hull girder response significantly. Focus in the present paper is on the influence of the hull girder flexibility on the extreme response amidships, namely the wave-induced vertical bending moment (VBM) in hogging, and the prediction of the extreme value of the same. The analysis...... in the present paper is based on time series of full scale measurements from three large container ships of 8600, 9400 and 14000 TEU. When carrying out the extreme value estimation the peak-over-threshold (POT) method combined with an appropriate extreme value distribution is applied. The choice of a proper...... threshold level as well as the statistical correlation between clustered peaks influence the extreme value prediction and are taken into consideration in the present paper....

  3. Dynamical Changes Induced by the Very Large Solar Proton Events in October-November 2003

    Science.gov (United States)

    Jackman, Charles H.; Roble, Raymond G.

    2006-01-01

    The very large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth and impacted the upper atmospheric polar cap regions. The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Mode (TIME-GCM) was used to study the atmospheric dynamical influence of the solar protons that occurred in Oct-Nov 2003, the fourth largest period of SPEs measured in the past 40 years. The highly energetic solar protons caused ionization and changes in the electric field, which led to Joule heating of the mesosphere and lower thermosphere. This heating led to temperature increases up to 4K in the upper mesosphere. The solar proton-induced ionization, as well as dissociation processes, led to the production of odd hydrogen (HO(x)) and odd nitrogen (NO(y)). Substantial (>40%) short-lived ozone decreases followed these enhancements of HO(x) and NO(y) and led to a cooling of the mesosphere and upper stratosphere. This cooling led to temperature decreases up to 2.5K. The solar proton-caused temperature changes led to maximum meridional and zonal wind variations of +/- 2 m/s on background winds up to +/- 30 m/s. The solar proton-induced wind perturbations were computed to taper off over a period of several days past the SPEs. Solar cycle 23 was accompanied by ten very large SPEs between 1998 and 2005, along with numerous smaller events. These solar proton-driven atmospheric variations need to be carefully considered when examining other polar changes.

  4. Contribution to the pathogenesis of radiation-induced injury to large arteries

    International Nuclear Information System (INIS)

    Zidar, Nina; Ferluga, Dusan; Hvala, Asta; Popovic, Mara; Soba, Erika

    1997-01-01

    We report a case of a 35-year-old man who died of a brain infarct 20 months after radiotherapy for carcinoma of the tonsil with metastases to the cervical lymph nodes. Histology revealed mild atherosclerosis, necrotizing vasculitis, and occlusive thrombosis of the internal carotid artery. Significant changes were observed in the vasa vasorum; swelling and detachment of the endothelium, subendothelial oedema, hyaline change, fibrinoid necrosis of the vessel walls with mononuclear cellular infiltration, accompanied by focal haemorrhages and chronic inflammation in the periadventitial soft tissue. We believe that these changes of the vasa vasorum and necrotizing vasculitis are causally related and that vasculitis represents focal ischaemic necroses with inflammatory reaction. Our findings support the hypothesis, based on experimental studies, that injury to the vasa vasorum is an important mechanism in the development of radiation-induced vasculopathy of large arteries. They also suggest an evolution of the injury to the vasa vasorum and periadventitial tissue from the early lesions described in our patient, to late stages resulting in dense periadventitial fibrosis as reported previously. We suggest that injury to the vasa vasorum and the consequent ischaemic lesions of the arterial wall are morphological features distinguishing radiation-induced arterial injury from spontaneous atherosclerosis. (author)

  5. Chronic respiratory aeroallergen exposure in mice induces epithelial-mesenchymal transition in the large airways.

    Directory of Open Access Journals (Sweden)

    Jill R Johnson

    Full Text Available Chronic allergic asthma is characterized by Th2-polarized inflammation and leads to airway remodeling and fibrosis but the mechanisms involved are not clear. To determine whether epithelial-mesenchymal transition contributes to airway remodeling in asthma, we induced allergic airway inflammation in mice by intranasal administration of house dust mite (HDM extract for up to 15 consecutive weeks. We report that respiratory exposure to HDM led to significant airway inflammation and thickening of the smooth muscle layer in the wall of the large airways. Transforming growth factor beta-1 (TGF-β1 levels increased in mouse airways while epithelial cells lost expression of E-cadherin and occludin and gained expression of the mesenchymal proteins vimentin, alpha-smooth muscle actin (α-SMA and pro-collagen I. We also observed increased expression and nuclear translocation of Snail1, a transcriptional repressor of E-cadherin and a potent inducer of EMT, in the airway epithelial cells of HDM-exposed mice. Furthermore, fate-mapping studies revealed migration of airway epithelial cells into the sub-epithelial regions of the airway wall. These results show the contribution of EMT to airway remodeling in chronic asthma-like inflammation and suggest that Th2-polarized airway inflammation can trigger invasion of epithelial cells into the subepithelial regions of the airway wall where they contribute to fibrosis, demonstrating a previously unknown plasticity of the airway epithelium in allergic airway disease.

  6. Methyl CpG–binding proteins induce large-scale chromatin reorganization during terminal differentiation

    Science.gov (United States)

    Brero, Alessandro; Easwaran, Hariharan P.; Nowak, Danny; Grunewald, Ingrid; Cremer, Thomas; Leonhardt, Heinrich; Cardoso, M. Cristina

    2005-01-01

    Pericentric heterochromatin plays an important role in epigenetic gene regulation. We show that pericentric heterochromatin aggregates during myogenic differentiation. This clustering leads to the formation of large chromocenters and correlates with increased levels of the methyl CpG–binding protein MeCP2 and pericentric DNA methylation. Ectopic expression of fluorescently tagged MeCP2 mimicked this effect, causing a dose-dependent clustering of chromocenters in the absence of differentiation. MeCP2-induced rearrangement of heterochromatin occurred throughout interphase, did not depend on the H3K9 histone methylation pathway, and required the methyl CpG–binding domain (MBD) only. Similar to MeCP2, another methyl CpG–binding protein, MBD2, also increased during myogenic differentiation and could induce clustering of pericentric regions, arguing for functional redundancy. This MeCP2- and MBD2-mediated chromatin reorganization may thus represent a molecular link between nuclear genome topology and the epigenetic maintenance of cellular differentiation. PMID:15939760

  7. Electric-field-induced extremely large change in resistance in graphene ferromagnets

    Science.gov (United States)

    Song, Yu

    2018-01-01

    A colossal magnetoresistance (˜100×10^3% ) and an extremely large magnetoresistance (˜1×10^6% ) have been previously explored in manganite perovskites and Dirac materials, respectively. However, the requirement of an extremely strong magnetic field (and an extremely low temperature) makes them not applicable for realistic devices. In this work, we propose a device that can generate even larger changes in resistance in a zero-magnetic field and at a high temperature. The device is composed of graphene under two strips of yttrium iron garnet (YIG), where two gate voltages are applied to cancel the heavy charge doping in the YIG-induced half-metallic ferromagnets. By calculations using the Landauer-Büttiker formalism, we demonstrate that, when a proper gate voltage is applied on the free ferromagnet, changes in resistance up to 305×10^6% (16×10^3% ) can be achieved at the liquid helium (nitrogen) temperature and in a zero magnetic field. We attribute such a remarkable effect to a gate-induced full-polarization reversal in the free ferromagnet, which results in a metal-state to insulator-state transition in the device. We also find that the proposed effect can be realized in devices using other magnetic insulators, such as EuO and EuS. Our work should be helpful for developing a realistic switching device that is energy saving and CMOS-technology compatible.

  8. Large magnetoresistance dips and perfect spin-valley filter induced by topological phase transitions in silicene

    Science.gov (United States)

    Prarokijjak, Worasak; Soodchomshom, Bumned

    2018-04-01

    Spin-valley transport and magnetoresistance are investigated in silicene-based N/TB/N/TB/N junction where N and TB are normal silicene and topological barriers. The topological phase transitions in TB's are controlled by electric, exchange fields and circularly polarized light. As a result, we find that by applying electric and exchange fields, four groups of spin-valley currents are perfectly filtered, directly induced by topological phase transitions. Control of currents, carried by single, double and triple channels of spin-valley electrons in silicene junction, may be achievable by adjusting magnitudes of electric, exchange fields and circularly polarized light. We may identify that the key factor behind the spin-valley current filtered at the transition points may be due to zero and non-zero Chern numbers. Electrons that are allowed to transport at the transition points must obey zero-Chern number which is equivalent to zero mass and zero-Berry's curvature, while electrons with non-zero Chern number are perfectly suppressed. Very large magnetoresistance dips are found directly induced by topological phase transition points. Our study also discusses the effect of spin-valley dependent Hall conductivity at the transition points on ballistic transport and reveals the potential of silicene as a topological material for spin-valleytronics.

  9. Experimental study of strain prediction on wave induced structures using modal decomposition and quasi static Ritz vectors

    DEFF Research Database (Denmark)

    Skafte, Anders; Kristoffersen, Julie; Vestermark, Jonas

    2017-01-01

    into two parts using complementary filters: Low frequency response caused by the quasi-static effect of the waves acting on the structure, and the high frequency response given by the modal properties of the structure. The high frequency response is then decomposed into modal coordinates using...... the experimental mode shapes. Strain histories are predicted by multiplying the modal coordinates with the expanded strain mode shapes. The low frequency response is decomposed using Ritz-vectors corresponding to the shapes that the structure vibrates with due to the wave loading. Strain Ritz......-vectors are then extracted from the finite element model by applying a load corresponding to a representative wave and the strain history for the low frequency response is found by multiplying the decomposed signal with the strain Ritz-vectors. Finally the combined strain history is found by adding the strain histories from...

  10. Field-induced strain and polarization response in lead-free Bi1/2(Na0.80K0.20)1/2TiO3–SrZrO3 ceramics

    International Nuclear Information System (INIS)

    Hussain, Ali; Rahman, Jamil Ur; Zaman, Arif; Malik, Rizwan Ahmed; Kim, Jin Soo; Song, Tae Kwon; Kim, Won Jeong; Kim, Myong Ho

    2014-01-01

    The structure, field-induced strain, polarization and dielectric response of lead-free SrZrO 3 -modified Bi 1/2 (Na 0.80 K 0.20 ) 1/2 TiO 3 (abbreviated as BNKT–SZ100x, with x = 0–0.05) ceramics were investigated. The X-ray diffraction analysis of BNKT–SZ100x ceramics reveals no remarkable change in the crystal structure within the studied composition range. Around critical composition (x = 0.03) at a driving field of 6 kV mm −1 , large unipolar strain of 0.37% (S max /E max = 617) was obtained at room temperature. The ferroelectric and piezoelectric properties of BNKT ceramics were significantly increased at 2 mol%. At x = 0.02, remnant polarization reached a maximum value of 34 μC cm −2 , while the piezoelectric constant (d 33 ) attained maximum value of 190 pC/N. These results indicate that BNKT–SZ100x ceramics can be considered as promising candidate materials for lead-free piezoelectric actuator applications. - Highlights: • BNKT–SZ ceramics were synthesized by a conventional solid state reaction process. • Field-induced strain and piezoelectric constant were increased at critical composition. • BNKT–SZ100x ceramics at x = 0.03 exhibit a large field induced dynamic piezoelectric coefficient. • BNKT–SZ100x ceramics at x = 0.02 exhibit a high static piezoelectric constant. • The depolarization temperature of BNKT–SZ100x ceramics decrease with increase in SZ content

  11. Ultraviolet radiation-induced mutability of isogenic uvrA and uvrB strains of Escherichia coli K-12 W3110

    International Nuclear Information System (INIS)

    Barfknecht, T.R.; Smith, K.C.

    1977-01-01

    E. coli K-12 W3110 uvrB5 strain has been shown to have a higher UV induced reversion frequency than its wild-type parent when plotted on the basis of mutation frequency versus survival. However for the E. coli B/r WP2s uvrA strain this higher mutability has been observed only at survival levels of 80-100%. A study was undertaken to determine if these differences in UV mutability were due primarily to the uvrA and uvrB mutations, or to other genetic background differences. Isogenic strains of E. coli K-12 W3110 carrying uvrA6, uvrB5, uvrA6 and uvrB5, and the uvrA allele from E.coli B/r WP2s were used. Results indicate that the enrichment of minimal medium with a small amount of nutrient broth is sufficient to inhibit minimal medium recovery (MMR) and to enhance leu + reversion of the leu B missense mutation in these uvr - strains. This suggests that there may be a relationship between MMR and error-free postreplication repair. Further research is in progress to clarify the relationship between MMR and broth enhancement of UV-induced mutagenesis in uvr - strains of E. Coli K-12 W3110. (author)

  12. Ultraviolet radiation-induced mutability of isogenic uvrA and uvrB strains of Escherichia coli K-12 W3110

    Energy Technology Data Exchange (ETDEWEB)

    Barfknecht, T R; Smith, K C [Stanford Univ., Calif. (USA). Dept. of Radiology

    1977-12-01

    Escherichia coli K-12 W3110 uvrB5 strain has been shown to have a higher uv-induced reversion frequency than its wild-type parent when plotted on the basis of mutation frequency versus survival. However for the E. coli B/r WP2s uvrA strain this higher mutability has been observed only at survival levels of 80 to 100%. A study was undertaken to determine if ly to the uvrA and uvrB mutations, or to other genetic background differences. Isogenic strains of E. coli K-12 W3110 carrying uvrA6, uvrB5, uvrA6, and uvrB5, and the uvrA allele from E.coli B/r WP2s were used. Results indicate that the enrichment of minimal medium with a small amount of nutrient broth is sufficient to inhibit minimal medium recovery (MMR) and to enhance leu/sup +/ reversion of the leu B missense mutation in these uvr/sup -/ strains. This suggests that there may be a relationship between MMR and error-free postreplication repair. Further research is in progress to clarify the relationship between MMR and broth enhancement of uv-induced mutagenesis in uvr/sup -/ strains of E. Coli K-12 W3110.

  13. Serial Changes of Tendon Histomorphology and Strain Elastography After Induced Achilles Tendinopathy in Rabbits: An In Vivo Study.

    Science.gov (United States)

    Ahn, Kyung-Sik; Lee, Nam Joon; Kang, Chang Ho; Lee, Young Hen; Jeon, Hae Jeong

    2017-04-01

    The purpose of this study was to investigate and compare the serial changes of morphology and strain in the early process of Achilles tendinopathy in a rabbit model. A total of 10 New Zealand white rabbits underwent ligation of one of their Achilles tendons to induce ischemic injury. Both inflamed and contralateral Achilles tendons were serially evaluated with 3 follow-ups: the first on days 3 to 5, the second on days 9 to 13, and the third and last follow-up on days 15 to 20 after surgery. During each examination, tendon thickness was measured and red, green, and blue pixel intensities of the elastogram were analyzed using color histogram analysis software. Differences between the inflamed and control group were compared. The mean thickness of the inflamed tendons increased during consecutive follow-ups and was significantly larger than that of control tendons (P tendons was also serially increased and was higher than that in the control tendons, indicating softening. However, the difference was significant only in the second and third follow-ups (P Tendon thickening and softening developed during the early process of Achilles tendinopathy in a rabbit model. Tendon softening may present later than thickening. © 2017 by the American Institute of Ultrasound in Medicine.

  14. Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

    KAUST Repository

    Mei, Yaochuan

    2017-08-02

    The temperature dependence of the charge-carrier mobility provides essential insight into the charge transport mechanisms in organic semiconductors. Such knowledge imparts critical understanding of the electrical properties of these materials, leading to better design of high-performance materials for consumer applications. Here, we present experimental results that suggest that the inhomogeneous strain induced in organic semiconductor layers by the mismatch between the coefficients of thermal expansion (CTE) of the consecutive device layers of field-effect transistors generates trapping states that localize charge carriers. We observe a universal scaling between the activation energy of the transistors and the interfacial thermal expansion mismatch, in which band-like transport is observed for similar CTEs, and activated transport otherwise. Our results provide evidence that a high-quality semiconductor layer is necessary, but not sufficient, to obtain efficient charge-carrier transport in devices, and underline the importance of holistic device design to achieve the intrinsic performance limits of a given organic semiconductor. We go on to show that insertion of an ultrathin CTE buffer layer mitigates this problem and can help achieve band-like transport on a wide range of substrate platforms.

  15. Recharging processes, radiation induced strain and changes of OH - bands under H + ion implantation in Ti doped lithium niobate

    Science.gov (United States)

    Kumar, P.; Moorthy Babu, S.; Bhaumik, I.; Ganesamoorthy, S.; Karnal, A. K.; Kumar, Praveen; Rodrigues, G. O.; Sulania, I.; Kanjilal, D.; Pandey, A. K.; Raman, R.

    2010-01-01

    A systematic analysis of variations in structural and optical characteristics of Z-cut plates of titanium doped congruent lithium niobate single crystals implanted with 120 keV proton beam at various fluences of 10 15, 10 16 and 10 17 protons/cm 2 is presented. Through, high resolution X-ray diffraction, atomic force microscopy, Fourier transform infrared and UV-visible-NIR analysis of congruent lithium niobate, the correlation of properties before and after implantation are discussed. HRXRD (0 0 6) reflection by Triple Crystal Mode shows that both tensile and compressive strain peak are produced by the high fluence implantation. A distinct tensile peak was observed from implanted region for a fluence of 10 16 protons/cm 2. AFM micrographs indicate mountain ridges, bumps and protrusions on target surface on implantation. UV-visible-NIR spectra reveal an increase in charge transfer between Ti 3+/Ti 4+ and ligand oxygen for implantation with 10 15 protons/cm 2, while spectra for higher fluence implanted samples show complex absorption band in the region from 380-1100 nm. Variations of OH - stretching vibration mode were observed for cLN Pure, cLNT2% virgin, and implanted samples with FTIR spectra. The concentration of OH - ion before and after implantation was calculated from integral absorption intensity. The effect of 120 keV proton implantation induced structural, surface and optical studies were correlated.

  16. Cold exposure affects carbohydrates and lipid metabolism, and induces Hog1p phosphorylation in Dekkera bruxellensis strain CBS 2499.

    Science.gov (United States)

    Galafassi, Silvia; Toscano, Marco; Vigentini, Ileana; Zambelli, Paolo; Simonetti, Paolo; Foschino, Roberto; Compagno, Concetta

    2015-05-01

    Dekkera bruxellensis is a yeast known to affect the quality of wine and beer. This species, due to its high ethanol and acid tolerance, has been reported also to compete with Saccharomyces cerevisiae in distilleries producing fuel ethanol. In order to understand how this species responds when exposed to low temperatures, some mechanisms like synthesis and accumulation of intracellular metabolites, changes in lipid composition and activation of the HOG-MAPK pathway were investigated in the genome sequenced strain CBS 2499. We show that cold stress caused intracellular accumulation of glycogen, but did not induce accumulation of trehalose and glycerol. The cellular fatty acid composition changed after the temperature downshift, and a significant increase of palmitoleic acid was observed. RT-PCR analysis revealed that OLE1 encoding for Δ9-fatty acid desaturase was up-regulated, whereas TPS1 and INO1 didn't show changes in their expression. In D. bruxellensis Hog1p was activated by phosphorylation, as described in S. cerevisiae, highlighting a conserved role of the HOG-MAP kinase signaling pathway in cold stress response.

  17. Strain-induced cracking corrosion in pipelines of conventional power plants; Dehnungsinduzierte Risskorrosion in Rohrsystemen von konventionellen Kraftwerksanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Adamsky, F.J.; Kempkes, B. [PreussenElektra Engineering GmbH, Gelsenkirchen (Germany); Ernst, J. [RWE Energie AG, Essen (Germany)

    2000-07-01

    Since the mid-sixties, stress corrosion cracking has been reported in highly loaded components of conventional power plants. Damage investigations were followed by extensive fundamental studies on crack initiation and propagation mechanisms, with particular regard to the water quality. The contribution presents causes, patterns, preferred sites and operating conditions of strain-induced corrosion. [German] Seit Anfang der 60er-Jahre wird ueber Risskorrosionsschaeden im wasserberuehrten Teil konventioneller Kraftwerksanlagen berichtet, die stets an hochbeanspruchten Bereichen festzustellen sind - vorwiegend in unrunden Rohrbogen oder Fallrohrbohrungen von Kesseltrommeln. Den Schadensuntersuchungen schlossen sich umfangreiche Grundsatzuntersuchungen an, um den Mechanismus von Rissbildung und Rissfortschritt kennenzulernen und daraus dann Abhilfemassnahmen abzuleiten. Bei schadhaften Rohrboegen stellte man in den Rissbereichen meist hoehere Unrundheiten fest und bei Kesseltrommeln Spannungsspitzen an den Lochraendern. Der Wasse