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Sample records for me49 strain experimentally

  1. Experimental infection with the Toxoplasma gondii ME-49 strain in the Brazilian BR-1 mini pig is a suitable animal model for human toxoplasmosis.

    PubMed

    Miranda, Farlen José Bebber; Souza, Diogo Benchimol de; Frazão-Teixeira, Edwards; Oliveira, Fábio Conceição de; Melo, João Cardoso de; Mariano, Carlos Magno Anselmo; Albernaz, Antonio Peixoto; Carvalho, Eulógio Carlos Queiróz de; Oliveira, Francisco Carlos Rodrigues de; Souza, Wanderley de; DaMatta, Renato Augusto

    2015-02-01

    Toxoplasma gondii causes toxoplasmosis, a worldwide disease. Experimentation with pigs is necessary for the development of new therapeutic approaches to human diseases. BR-1 mini pigs were intramuscularly infected with T. gondii with tachyzoites (RH strain) or orally infected with cysts (ME-49 strain). Haematology and serum biochemistry were analysed and buffy coat cells were inoculated in mice to determine tachyzoite circulation. No alterations were observed in erythrocyte and platelet values; however, band neutrophils increased seven days after infection with ME-49. Serology of the mice inoculated with pig blood leucocytes revealed circulating ME-49 or RH strain tachyzoites in the pigs' peripheral blood at two and seven or nine days post-infection. The tachyzoites were also directly observed in blood smears from the infected pigs outside and inside leucocytes for longer periods. Alanine-aminotransferase was high at days 21 and 32 in the RH infected pigs. After 90 days, the pigs were euthanised and their tissue samples were processed and inoculated into mice. The mice serology revealed the presence of parasites in the hearts, ileums and mesenteric lymph nodes of the pigs. Additionally, cysts in the mice were only observed after pig heart tissue inoculation. The infected pigs presented similar human outcomes with relatively low pathogenicity and the BR-1 mini pig model infected with ME-49 is suitable to monitor experimental toxoplasmosis.

  2. Experimental infection with the Toxoplasma gondii ME-49 strain in the Brazilian BR-1 mini pig is a suitable animal model for human toxoplasmosis.

    PubMed

    Miranda, Farlen José Bebber; Souza, Diogo Benchimol de; Frazão-Teixeira, Edwards; Oliveira, Fábio Conceição de; Melo, João Cardoso de; Mariano, Carlos Magno Anselmo; Albernaz, Antonio Peixoto; Carvalho, Eulógio Carlos Queiróz de; Oliveira, Francisco Carlos Rodrigues de; Souza, Wanderley de; DaMatta, Renato Augusto

    2015-02-03

    Toxoplasma gondii causes toxoplasmosis, a worldwide disease. Experimentation with pigs is necessary for the development of new therapeutic approaches to human diseases. BR-1 mini pigs were intramuscularly infected with T. gondii with tachyzoites (RH strain) or orally infected with cysts (ME-49 strain). Haematology and serum biochemistry were analysed and buffy coat cells were inoculated in mice to determine tachyzoite circulation. No alterations were observed in erythrocyte and platelet values; however, band neutrophils increased seven days after infection with ME-49. Serology of the mice inoculated with pig blood leucocytes revealed circulating ME-49 or RH strain tachyzoites in the pigs' peripheral blood at two and seven or nine days post-infection. The tachyzoites were also directly observed in blood smears from the infected pigs outside and inside leucocytes for longer periods. Alanine-aminotransferase was high at days 21 and 32 in the RH infected pigs. After 90 days, the pigs were euthanised and their tissue samples were processed and inoculated into mice. The mice serology revealed the presence of parasites in the hearts, ileums and mesenteric lymph nodes of the pigs. Additionally, cysts in the mice were only observed after pig heart tissue inoculation. The infected pigs presented similar human outcomes with relatively low pathogenicity and the BR-1 mini pig model infected with ME-49 is suitable to monitor experimental toxoplasmosis.

  3. Experimental infection with the Toxoplasma gondii ME-49 strain in the Brazilian BR-1 mini pig is a suitable animal model for human toxoplasmosis

    PubMed Central

    Miranda, Farlen José Bebber; de Souza, Diogo Benchimol; Frazão-Teixeira, Edwards; de Oliveira, Fábio Conceição; de Melo, João Cardoso; Mariano, Carlos Magno Anselmo; Albernaz, Antonio Peixoto; de Carvalho, Eulógio Carlos Queiróz; de Oliveira, Francisco Carlos Rodrigues; de Souza, Wanderley; DaMatta, Renato Augusto

    2015-01-01

    Toxoplasma gondii causes toxoplasmosis, a worldwide disease. Experimentation with pigs is necessary for the development of new therapeutic approaches to human diseases. BR-1 mini pigs were intramuscularly infected with T. gondii with tachyzoites (RH strain) or orally infected with cysts (ME-49 strain). Haematology and serum biochemistry were analysed and buffy coat cells were inoculated in mice to determine tachyzoite circulation. No alterations were observed in erythrocyte and platelet values; however, band neutrophils increased seven days after infection with ME-49. Serology of the mice inoculated with pig blood leucocytes revealed circulating ME-49 or RH strain tachyzoites in the pigs' peripheral blood at two and seven or nine days post-infection. The tachyzoites were also directly observed in blood smears from the infected pigs outside and inside leucocytes for longer periods. Alanine-aminotransferase was high at days 21 and 32 in the RH infected pigs. After 90 days, the pigs were euthanised and their tissue samples were processed and inoculated into mice. The mice serology revealed the presence of parasites in the hearts, ileums and mesenteric lymph nodes of the pigs. Additionally, cysts in the mice were only observed after pig heart tissue inoculation. The infected pigs presented similar human outcomes with relatively low pathogenicity and the BR-1 mini pig model infected with ME-49 is suitable to monitor experimental toxoplasmosis. PMID:25742268

  4. Morphometric changes in C57BL/6 mice retina infected by Toxoplasma gondii ME 49 strain.

    PubMed

    Rocha, Ana Cristina Higino; Calabrese, Kátia da Silva; Tedesco, Roberto Carlos; Campos, Wesley Ribeiro; Neto, Miguel Houri; Vasconcelos, Anilton Cezar; Oréfice, Fernando

    2014-01-01

    This study evaluated the morphometric implications in C57BL/6 mouse retina infected by Toxoplasma gondii, ME 49 strain. Twenty C57BL/6 female mice were divided into group 1 (n=8, intraperitoneally infected with 30 cysts of T. gondii ME 49 strain) and group 2 (n=12 non-infected controls). The eyes were enucleated on the 60th day after infection, fixed and processed for light microscopy. Changes in retinal thickness and in the perimeter/area ratio (P/A) of the retinal layers were analyzed by digital morphometry. We considered that P/A was the measurement of retinal architecture distortion induced by toxoplasmosis. This study considered the ganglion cells and nerve fiber layers as a monolayer, thus six layers of retina were evaluated: photoreceptors (PRL), outer nuclear (ONL), outer plexiform (OPL), inner nuclear (INL), inner plexiform (IPL) and ganglion cells/nerve fiber monolayer (GNL). Histological analysis of infected mouse retina showed inflammatory infiltrate, necrosis, glial reaction and distortion of the retina architecture. It also presented increased thickness (167.8±24.9μm versus 121.1±15.4μm, in controls) and increased retinal thickness within the retinitis foci (187.7±16.6μm versus 147.9±12.2μm out of the retinitis foci). A statistically significant difference in P/A was observed between infected and uninfected mouse retinas. The same was observed in PRL, OPL, INL and GNL. Retinal morphometry may be used to demonstrate differences between infected and uninfected mouse retinas.

  5. Influence of infection by Toxoplasma gondii on purine levels and E-ADA activity in the brain of mice experimentally infected mice.

    PubMed

    Tonin, Alexandre A; Da Silva, Aleksandro S; Casali, Emerson A; Silveira, Stephanie S; Moritz, Cesar E J; Camillo, Giovana; Flores, Mariana M; Fighera, Rafael; Thomé, Gustavo R; Morsch, Vera M; Schetinger, Maria Rosa C; Rue, Mario De La; Vogel, Fernanda S F; Lopes, Sonia T A

    2014-07-01

    The aim of this study was to assess the purine levels and E-ADA activity in the brain of mice (BALB/c) experimentally infected with Toxoplasma gondii. In experiment I (n=24) the mice were infected with RH strain of T. gondii, while in experiment II (n=36) they were infected with strain ME-49 of T. gondii. Our results showed that, for RH strain (acute phase), an increase in both periods in the levels of ATP, ADP, AMP, adenosine, hypoxanthine, xanthine (only on day 6 PI) and uric acid (only on day 6 PI). By the other hand, the RH strain led, on days 4 and 6 PI, to a reduction in the concentration of inosine. ME-49, a cystogenic strain, showed some differences in acute and chronic phase, since on day 6 PI the levels of ATP and ADP were increased, while on day 30 these same nucleotides were reduced. On day 60 PI, ME-49 induced a reduction in the levels of ATP, ADP, AMP, adenosine, inosine and xanthine, while uric acid was increased. A decrease of E-ADA activity was observed in brain on days 4 and 6 PI (RH), and 30 PI (ME-49); however on day 60 PI E-ADA activity was increased for infection by ME-49 strain. Therefore, it was possible to conclude that infection with T. gondii changes the purine levels and the activity of E-ADA in brain, which may be associated with neurological signs commonly observed in this disease.

  6. Tests of strain analysis by experimental deformation

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.; McArthur, J.

    1991-01-01

    The linearisation method and Robin's method of strain analysis of granular materials yield accurate strain estimates for a variety of materials deformed experimentally in pure shear. The breakdown of continuum behaviour at high pore fluid pressures causes the methods to overestimate the strain because they do not take added rigid-body rotation into account. Both methods tolerate some variation in initial shape ratio and some degree of initial preferred orientation at modest strains. Results of tests on polymict sandstone indicate that the lower than average ductility of competent clasts may be balanced against an unfavourable degree of preferred orientation to yield an improved strain estimate.

  7. Tectonic strain and paleomagnetism: experimental investigation

    NASA Astrophysics Data System (ADS)

    Borradaile, G.; Mothersill, J.

    1989-09-01

    A porous, clay-rich sandstone with a natural remanent magnetisation shows complex changes in the orientation of the remanence vector when the sandstone is subjected to experimental deformation, at 100 MPa, room temperature and constant natural strain rates of 1 × 10 -5 s -1. The paleomagnetic vector does not simply rotate away from the axis of compression. When the rock is shortened perpendicular to bedding the remanence vector rotates toward the bedding, as expected, but the remanence also rotates toward bedding when the rock is shortened parallel to bedding. Moreover, in some cases the remanence vector changes azimuth within the specimen during experimental deformation. Thus bedding anisotropy and the accompanying mineral-fabric anisotropy are more influential than strain in controlling deflections of the paleomagnetic vector in this study. This anisotropy also influences the post-deformational behaviour of remanence: 4 months after deformation, some cores shortened perpendicular to bedding relaxed their remanence vectors back towards the pre-deformational attitude whereas some other cores continued to show progressive changes. Intragranular, recoverable elastic strains in the magnetic grains may be partly responsible for the experimentally induced deflections of remanence.

  8. Experimental qualification by extensive evaluation of fibre optic strain sensors

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Kusche, Nadine; Schukar, Vivien G.; Münzenberger, Sven; Habel, Wolfgang R.

    2013-09-01

    Fibre optic strain sensors used in practical applications have to provide reliable measurements. Therefore, the applied sensor and the sensor systems must be validated experimentally. This can be achieved with facilities which use physically independent measurement systems in order to avoid the influences caused by the application of a reference sensor. This paper describes the testing methods of the specially developed validation facility KALFOS for the qualification and evaluation of surface-applied strain sensors. For reliable sensor results, the performance of fibre optic strain patches with and without FBG under combined thermal and mechanical loading was investigated. Additionally, the strain gauge factor of the fibre optic strain patches with FBG was determined experimentally and compared to the specified strain gauge factor. These results will be the basis for the development of guidelines and standards concerning the application of the sensors.

  9. An experimental/analytical comparison of strains in encapsulated assemblies

    SciTech Connect

    Guess, T.R.; Burchett, S.N.

    1991-11-01

    A combined experimental and analytical study of strains developed in encapsulated assemblies during casting, curing and thermal excursions is described. The experimental setup, designed to measure in situ strains, consisted of thin, closed-end, Kovar tubes that were instrumented with strain gages and thermocouples before being over-cast with a polymeric encapsulant. Four bisphenol A (three diethanolamine cured and one anhydride cured) epoxy-based materials and one urethane elastomeric material were studied. After cure of the encapsulant, tube strains were measured over the temperature range of {minus}55{degrees}C to 90{degrees}C. The thermal excursion experiments were then numerically modeled using finite element analyses and the computed strains were compared to the experimental strains. The predicted strains were over estimated (conservative) when a linear, elastic, temperature-dependent material model was assumed for the encapsulant and the stress free temperature T{sub i} was assumed to correspond to the cure temperature {Tc} of the encapsulant. Very good agreement was obtained with linear elastic calculations provided that the stress free temperature corresponded to the onset of the glassy-to-rubbery transition range of the encapsulant. Finally, excellent agreement was obtained in one of the materials (828/DEA) when a viscoelastic material model was utilized and a stress free temperature corresponding to the cure temperature was assumed. 13 refs., 20 figs., 3 tabs.

  10. An experimental/analytical study of strains in encapsulated assemblies

    NASA Astrophysics Data System (ADS)

    Guess, T. R.; Burchett, S. N.

    1991-12-01

    A combined experimental and analytical study of strains that develop in encapsulated assemblies during casting, curing and thermal excursions is described. The experimental setup, designed to measure in situ strains, consisted of thin, closed-end, metal tubes that were instrumented with strain gages and thermocouples before being over-potted with an encapsulant. Three epoxy-based materials were studied. After cure of the encapsulant, tube strains were measured over the temperature range of minus 55 C to 90 C. The thermal excursion experiments were then numerically modeled using finite element analyses and the results were compared to the experimental results. The predicted strains are overestimated (conservative) when a linear, elastic, temperature-dependent material model was assumed for the encapsulant and the stress free temperature was assumed to correspond to the cure temperature of the encapsulant. Very good agreement was obtained with the linear elastic calculations provided that the stress free temperature corresponds to the onset of the glassy-to-rubbery transition range of the encapsulant. Finally, very good agreement was obtained when a viscoelastic material model was utilized and a stress free temperature corresponding to the cure temperature was assumed.

  11. Theoretical and experimental plastic strain ratios in planar isotropic textures

    NASA Astrophysics Data System (ADS)

    Kim, Insoo

    1996-06-01

    The plastic strain ratios of planar isotropic sheet specimens were studied by using unidirectionally solidified commercial Al. Sn and Al-Cu alloy sheets and Cu sheets electrodeposited under the various electrolysis conditions. The measured plastic strain ratios of [100] planar isotropic sheets by using unidirectionally solidified Al and Al-Cu alloy are about 0.17-0.52, that of [110] planar isotropic sheets using unidirectionally solidified Sn(BCT) are about 2.5, that of [110] planar isotropic sheets using electrodeposited Cu are 1.38-2.05 and that of [111] planar isotropic sheets using electrodeposited Cu are 2.61-2.85. There is a substantial discrepancy between the experimental plastic strain ratios which are measured from planar isotropic sheets and theoretical plastic strain ratios which are calculated by Backofen method and Bunge method, but the measured plastic strain ratio of [100] planar isotropic sheet using unidirectionally solidified Al and Al-Cu alloy is in good agreement with Bunge method and the measured plastic strain ratio of [110] and [111] planar isotropic sheets using electrodeposited Cu are in good agreement with Backofen method.

  12. Perceptual strain index for heat strain assessment in an experimental study: an application to construction workers.

    PubMed

    Yang, Y; Chan, Albert P C

    2015-02-01

    Although the physiological strain index (PhSI) is universal and comprehensive, its restrictions are recognized in terms of invasive on-site measurements and the requirement of accurate instruments. The perceptual strain index (PeSI) has been proposed as a user-friendly and practical indicator for heat strain. However, the application of this index in assessing the heat strain of construction workers has yet to be examined and documented. This study aims to ascertain the reliability and applicability of PeSI in an experimental setting that simulates a stressful working environment (i.e., environment, work uniform, and work pace) experienced by construction workers. Ten males and two females performed intermittent exercise on a treadmill while wearing a summer work uniform at 34.5 °C and 75% relative humidity in a climatic chamber. Physiological parameters (core temperature, heart rate) and perceptual variables (thermal sensation, perceived exertion) were collated synchronously at 3 min intervals. The results of two-way repeated measures analysis of variance (clothing×time) revealed that the PeSI was useful in differentiating the heat strain levels between different work uniforms. Not only did the PeSI change in the same general manner with the PhSI, but it was also powerful in reflecting different levels of physiological strain. Thus, the PeSI offers considerable promise for heat strain assessment under simulated working conditions.

  13. Experimental Pneumocystis carinii pneumonia in different strains of cortisonized mice.

    PubMed Central

    Walzer, P D; Powell, R D; Yoneda, K

    1979-01-01

    Pneumocystis carinii pneumonia was produced in eight different strains of mice by the administration of corticosteroids, low (8%)-protein diet, and tetracycline in the drinking water. Heavier degrees of P. carinii infection were most consistently found in C3H/HeN mice; intermediate levels occurred in BALB/c AnN, C57BL/6N, B10.A(2R), AKR/J, and Swiss Webster mice; lighter degrees were found in DBA/2N and DBA/IJ mice. Histopathologically, P. carinii organisms were morphologically indistinguishable from human and rat P. carinii, and elicited a predominantly mononuclear response that was similar among the various mouse strains. The optimal cortisone acetate regimen was 1 mg injected subcutaneously twice weekly. Higher doses shortened the life span of the mice, presumably by inducing overwhelming bacterial infection. This problem occurred not only in different strains of mice, but also in the same strain of mice obtained from different breeders. Thus, cortisonized mice should be useful in the study of experimental P. carinii infection. Success of this model depends on the corticosteroid dose, as well as the strain, source, general health, and preexisting microbial flora of the mice chosen for study. Images PMID:313907

  14. Strain difference in rats with experimental giant cell myocarditis.

    PubMed

    Shioji, K; Kishimoto, C; Nakayama, Y; Sasayama, S

    2000-04-01

    Immunogenetic mechanisms may be involved in the pathogenesis of myocarditis and dilated cardiomyopathy. The present study investigated the incidence, histopathology and histocompatibility characteristics of experimental giant cell myocarditis in various strains of rats. Experimental giant cell myocarditis was induced by immunization with porcine cardiac myosin in Lewis (RT-1(l)), Dahl (DIR/Eis) (RT-1(l)), Fisher (RT-1(lv 1)) rats, but not in Dahl (DIS/Eis) (RT-1(l)) or Brown Norway (RT-1(n)). Myocarditis was most severe in the Lewis rats and their heart weight/body weight ratio was significantly higher than that of control rats immunized with Freund's complete adjuvant alone. In conclusion, this study provides evidence that the expression and severity of experimental giant cell myocarditis may be determined mainly by genetic factors, including both major histocompatibility complex genes as well as other genes, which may be controlled by an immune mechanism.

  15. Experimental determination of plastic strain in the extrusion process

    NASA Astrophysics Data System (ADS)

    Kronsteiner, J.; Horwatitsch, D.; Hinterer, A.; Gusenbauer, C.; Zeman, K.

    2016-10-01

    Simulating strain requires experimental validation. In this work, a method for the non-destructive determination of plastic strain in an extruded tube profile is presented. A copper coating, which deforms with the billet material, was used in the developed non-destructive method and was detected by computed tomography (CT) to analyze the deformation. The pattern was applied on cast billet halves (in the longitudinal direction) by a plasma coating technology. It was thus possible to determine the deformation of the pattern during the extrusion process in the billet as well as in the final profile without disassembling the extruded parts. A comparison of specimen using two different patterns shows the superiority of the simpler pattern consisting of only cross markers.

  16. Experimental and Computational Investigations of Strain Localization in Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Bharathula, Ashwini

    Metallic glasses are metallic alloy systems with disordered atomic structure. Due to their unique amorphous structure, they exhibit an extraordinary set of properties that are ideal for a wide variety of applications ranging from electrical transformers, armor-piercing projectiles, sporting goods and fuel cells to precision gears for micromotors. In particular, owing to their exceptional mechanical properties like near-theoretical strength (1--3 GPa), large elastic strain range (2--3%), and unusual formability above the glass transition temperature, metallic glasses have tremendous potential in structural applications. Unfortunately, their unique structure also gives rise to significant limitations, such as limited ductility at room temperature due to rapid localization of plastic flow in shear bands. However, when the test volumes approach the size of a shear band nucleus (˜50--500 nm), it is believed that shear band formation and propagation can be constrained, leading to enhanced plasticity and failure strength. This study investigates the phenomenon of strain localization using both experimental and computational techniques. On the experimental front, sample size effects on strength, plasticity and deformation modes were explored in a Zr-based bulk metallic glass via micron- and sub-micron scale compression testing. Specimens with diameters ranging from 200 nm to a few microns were fabricated using Focused Ion Beam technique and were tested under uniaxial compression in a nanoindentation set-up with a flat punch tip. Effect of extrinsic factors like specimen geometry and machine stiffness on deformation behavior was discussed. Shear banding was shown to be more stable at this length scale than in macro-scale testing because of a smaller specimen to load frame stiffness ratio. It was found that as the specimen size is reduced to below 300 nm, the deformation mode changes from being discrete and inhomogeneous to more continuous flow including both localized and

  17. Experimental Anelastic Strain Recovery Compliance of Three Typical Rocks

    NASA Astrophysics Data System (ADS)

    Gao, Lu; Lin, Weiren; Sun, Dongsheng; Wang, Hongcai

    2014-11-01

    The experimental determination of anelastic strain recovery (ASR) compliances for three types of rocks (granite, marble, and sandstone) was performed in the laboratory. Preloading of specimens for uniaxial compression creep tests was at 50 % of the uniaxial compressive strength (UCS) for each rock type. We obtained the shear mode Jas( t) and volumetric mode Jav( t) ASR compliances and calculated the ratio of Jas( t) to Jav( t). The Kelvin model for rock rheology was then applied in numerical simulations and the results were in good agreement with the measured data for Jas( t) and Jav( t). These results showed that both the magnitude and rate of increase of the ASR compliances are strongly dependent on the rock type, and the values of the Jas( t)/Jav( t) ratio for a loading of 50 % of the UCS showed a trend leading to different constants for each of the three rock types. Further experimental and numerical analyses showed approximate power-law relationships between the ASR compliances at 50 % of UCS, and both the UCS and the tangential Young's modulus at 50 % of UCS ( E t50). These relationships may be useful for the preliminary estimation of ASR compliances.

  18. Atomistic modeling at experimental strain rates and timescales

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Cao, Penghui; Tao, Weiwei; Sharma, Pradeep; Park, Harold S.

    2016-12-01

    Modeling physical phenomena with atomistic fidelity and at laboratory timescales is one of the holy grails of computational materials science. Conventional molecular dynamics (MD) simulations enable the elucidation of an astonishing array of phenomena inherent in the mechanical and chemical behavior of materials. However, conventional MD, with our current computational modalities, is incapable of resolving timescales longer than microseconds (at best). In this short review article, we briefly review a recently proposed approach—the so-called autonomous basin climbing (ABC) method—that in certain instances can provide valuable information on slow timescale processes. We provide a general summary of the principles underlying the ABC approach, with emphasis on recent methodological developments enabling the study of mechanically-driven processes at slow (experimental) strain rates and timescales. Specifically, we show that by combining a strong physical understanding of the underlying phenomena, kinetic Monte Carlo, transition state theory and minimum energy pathway methods, the ABC method has been found to be useful in a variety of mechanically-driven problems ranging from the prediction of creep-behavior in metals, constitutive laws for grain boundary sliding, void nucleation rates, diffusion in amorphous materials to protein unfolding. Aside from reviewing the basic ideas underlying this approach, we emphasize some of the key challenges encountered in our own personal research work and suggest future research avenues for exploration.

  19. Toxoplasma gondii strain-dependent effects on mouse behaviour.

    PubMed

    Kannan, Geetha; Moldovan, Krisztina; Xiao, Jian-Chun; Yolken, Robert H; Jones-Brando, Lorraine; Pletnikov, Mikhail V

    2010-06-01

    Toxoplasma gondii reportedly manipulates rodent behaviour to increase transmission to its definitive feline host. We compared the effects of mouse infection by two Type II strains of T. gondii, Prugniaud (PRU) and ME49, on attraction to cat odour, locomotor activity, anxiety, sensorimotor gating, and spatial working and recognition memory 2 months post-infection (mpi). Attraction to cat odour was reassessed 7 mpi. At 2 mpi, mice infected with either strain exhibited significantly more attraction to cat odour than uninfected animals did, but only PRU-infected mice exhibited this behaviour 7 mpi. PRU-infected mice had significantly greater body weights and hyperactivity, while ME49-infected mice exhibited impaired spatial working memory. No differences in parasite antibody titres were seen between PRU- and ME49-infected mice. The present data suggest the effect of T. gondii infection on mouse behaviour is parasite strain-dependent.

  20. Toxoplasma gondii: differential protection rates by two strains against cyst formation in a rat model.

    PubMed

    Freyre, A; Falcón, J; Mendez, J; González, M

    2006-12-01

    A previous infection with the ME-49 strain of Toxoplasma gondii (of low pathogenicity for mice), protected 17 of 20 rats against formation of brain cysts, following challenge with 10(3) oocysts of the high pathogenicity M3 strain, as determined by bioassay of rat brains in mice. The low pathogenic KSU strain did not afford comparable protection. Protection was further tested in rats that were orally or subcutaneously immunized with cysts or oocysts of the ME-49 strain, and later challenged with 2 x 10(2) cysts or 10(2) oocysts of the highly pathogenic strains M3, M-7741 and C. Protection ranged from 43 to 100%, compared to non immunized control rats and was independent of the stage of ME-49 strain and of the routes used to immunize the rats. The results obtained encourage further investigation into prevention of toxoplasmosis in humans and food animals.

  1. Dielectric anisotropy and strain of experimentally deformed talc aggregates

    NASA Astrophysics Data System (ADS)

    Borradaile, G.; Hawton, M.

    The electrical conductivity of talc aggregates containing adsorbed water is strongly influenced by the degree of preferred orientation of the talc crystals in the frequency range 10 Hz to 1 MHz. It is not influenced appreciably by the grain size of the talc in the range investigated. For specimens triaxially deformed at a confining pressure of 200 MPa there exists a limited powerlaw correlation between conductivity (at a frequency of 100 Hz) and strain ratio, up to a strain corresponding to an axial shortening of about 30%. At higher strains a saturation alignment is achieved which may cause the electrical conductivity to reach a plateau level.

  2. Experimental study on strain sensing by small-diameter FBG

    NASA Astrophysics Data System (ADS)

    Liu, Rong-mei; Li, Qiufeng; Zhu, Lujia; Liang, Dakai

    2016-11-01

    Fiber Bragg grating (FBG) sensors were attractive in various fields for structural health monitoring. Because of their accurate performance and real time response, embedded FBG sensors are promising for strain monitoring in composite materials. As an optical fiber sensor was embedded inside a composite, interface would form around the embedded optical fiber and the host polymer composite. In order to study the influence of the embedded optical fiber to the mechanical character, finite elemental analysis was applied to study the stress distribution inside the composite. Keeping the resin rich area the same size, laminates with optical fibers in different diameters, which were 250 and 125 micrometers, were analyzed. The simulation results represent that stress singularity would occur around the embedded optical fiber. The singularity value for the laminate with optical fiber at 250 micrometer was higher than that with optical fiber at 125 micrometer. Micro- cracks would arise at the stress singularity point. Therefore, the optical fiber in smaller diameter was preferred since the mechanical strength could be higher. Four points bending test was carried out on a steel beam with a small-diameter FBG on the bottom surface. Besides, a strain gauge was stuck on bottom to validate the monitoring results by FBG sensor. The tested results indicated that the strain monitoring results by the small-diameter FBG sensor almost identical with the theoretical ones and what recorded by strain gauge. The maximum testing error for the designed FBG is less than 2% compared with the theoretical one.

  3. A new experimental murine aspergillosis model to identify strains of Aspergillus fumigatus with reduced virulence.

    PubMed

    Sarfati, J; Diaquin, M; Debeaupuis, J P; Schmidt, A; Lecaque, D; Beauvais, A; Latge, J P

    2002-01-01

    Experimental animals are an obligate screen to investigate microorganism pathogenicity. Numerous animal models have been used to analyse the virulence of the opportunistic human pathogen Aspergillus fumigatus but none of the experimental models used previously have been satisfactory. This report discuss these models and presents a murine model of pulmonary aspergillosis that is very easy and the most adapted to compare the pathogenicity of A. fumigatus strains. Strains to be tested are inoculated intranasally and synchronously to mice and strains isolated from the lung of mice killed by the infection are typed. The number of colonies recovered is directly correlated to the virulence of the strain.

  4. Experimental study on strain distribution of ionic polymer-metal composite actuator using digital image correlation

    NASA Astrophysics Data System (ADS)

    Liu, Hongguang; Xiong, Ke; Wang, Man; Bian, Kan; Zhu, Kongjun

    2017-02-01

    Ionic polymer-metal composite (IPMC) cantilever actuators demonstrate significant bending deformation upon application of excitation voltage across the electrodes. In this paper a cantilever beam shaped IPMC actuator with platinum (Pt) electrodes is fabricated to investigate the micro-scale lateral deformation behavior under DC voltages using a digital microscope to measure the deformation. The digital image correlation (DIC) method is utilized to analyze the displacement and strain fields of the sample. The experimental results indicate that the longitudinal normal strain is linearly distributed along the thickness direction and the strain gradient is approximately exponential with excitation voltage. The amplitude of the transverse strain is bigger than the longitudinal strain, and the strains are also found to decrease along the length direction of the IPMC cantilever actuator. The longitudinal and transverse normal strains of the IPMC actuator under DC voltages are compressive strains due to water loss effect in the air.

  5. Design and experimental study on FBG hoop-strain sensor in pipeline monitoring

    NASA Astrophysics Data System (ADS)

    Ren, Liang; Jia, Zi-guang; Li, Hong-nan; Song, Gangbing

    2014-01-01

    Pipeline monitoring is an important task for the economic and safe operation of pipelines as well as for loss prevention and environmental protection. The circumferential strain is of significance in pipeline integrity monitoring. In this paper, an indirect pipeline corrosion monitoring method based on the circumferential strain measurement is firstly proposed, with main objectives at designing a circumferential strain measuring device. Combined with unique advantages of optical fiber sensing, an FBG hoop-strain sensor was designed and encapsulated. Its enhanced sensitivity mechanism in the circumferential strain measurement and manufacturing technique is detailed. The experimental study of the developed FBG hoop-strain sensor is conducted on a PVC model pipeline to investigate its characteristics, including reliability and some tentative dynamic tests. Results of model tests show that the FBG hoop-strain sensor demonstrates good performance in the circumferential strain measurement, and can be considered as a practical device for pipeline health monitoring.

  6. Experimental strain of isothermal remanent magnetization in ductile sandstone

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Mothersill, John S.

    A macroscopically ductile sandstone, to which a homogeneous isothermal remanent magnetization (IRM) was applied, has been deformed at 150 MPa confining pressure and constant strain rate of 10 -5 s -1. Hydrostatic compaction does not produce a deflection of the IRM vector although it is reduced in intensity. Pure shear producing shortening in the range 2 to 35% steadily reduces the intensity of magnetization but also homogeneously rotates the remanence vector toward the plane of flattening. The amount of rotation is slightly less than that expected for a non-material line undergoing homogeneous strain. Deformation selectively removes weakly coercive components of remanence, as revealed by alternating field (AF) demagnetization. During deformation a weak deformational viscous remanent magnetization (DVRM) is acquired from the pressure vessel. This is different from a conventional viscous remanent magnetization (VRM) in that it is not acquired when the specimen is subject to hydrostatic confining pressure alone, even for periods three times longer than the longest deformation test.

  7. Free edge strain concentrations in real composite laminates: Experimental-theoretical correlation

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Post, D.; Buczek, M. B.; Czarnek, R.

    1984-01-01

    The magnitude of the maximum shear strain at the free edge of axially loaded theta (2)/-theta(2)(s) and (+ or - theta(2) (s) composite laminates was investigated experimentally and numerically to ascertain the actual value of strain concentration in resin matrix laminates and to determine the accuracy of finite element results. Experimental results using moire interferometry show large, but finite, shear strain concentrations at the free edge of graphite-epoxy and graphite-polyimide laminates. Comparison of the experimental results with those obtained using several different finite element representations showed that a four node isoparametric finite element provided the best and most trouble free numerical results. The results indicate that the ratio of maxium shear strain at the free edge to applied axial strain varies with fiber orientation and does not exceed nine for the most critical angle which is 15 deg.

  8. Localized Strain Bands Before Stress Drop - An Experimental Study

    NASA Astrophysics Data System (ADS)

    Ji, Y.; Zhuo, Y. Q.; Liu, L.; Ma, J.

    2016-12-01

    High frequency observation indicates that there is a meta-instability stage (MIS) between a fault reaching the peak differential stress and the onset of the final stress drop. MIS is crucial because a fault transits from "stick" to "slip" during it. If one can quantitatively analyze the spatial and temporal characteristics of the deformation field of a fault at MIS, the result will be of great significance both to fault mechanics and earthquake prediction study. In order to do so, a series of stick-slip experiments were conducted on a biaxial servo-controlled pressure machine. Digital images of the sample surfaces were captured by a high speed camera and processed using a digital image correlation method (DIC). In our study, sample images were captured at the rate of 1000 frame per second and the resolution of 2048 by 2048 in pixel. The displacement filed, strain filed and fault displacement were calculated from the captured images. Our data shows that (1) pre-sliding can be a two-step process, including a relative long and slow first step and a short and fast second one. (2) Localized strain bands were observed oblique or nearly perpendicular to the fault. A possible mechanism is that the pre-sliding is distributed heterogeneously along the fault, which means there are relatively adequately sliding segments and the less sliding ones, they become the constrain condition of deformation of the adjacent sub-region. The localized deformation band tends to radiate from the discontinuity point of sliding. While the adequately sliding segments are competing with the less sliding ones, the strain bands are evolving accordingly.

  9. Experimental Evaluation of White Light Fabry-Perot Interferometry Fiber-Optic Strain Gages when Measuring Small Strains

    NASA Technical Reports Server (NTRS)

    St.Cyr, William; Figueroa, Fernando; VanDyke, David; McVay, Greg; Mitchell, Mark

    2002-01-01

    An experimental study was conducted to evaluate whether fiber optic strain gages (FOSG) are "better" sensors than typical foil gages. A particularly attractive feature of FOSG was their specified resolution of 0.01% of full-scale (0.1 micro strain for 1000 micro strain full-scale). This feature would make FOSG practical tank level sensors, by measuring very small strains on the support structure of a tank. A specific application in mind was to measure liquid oxygen tank level, with support beams that were predicted to contract approximately 11 micro strain as the tank goes from empty to full. Among various fiber optic technologies currently available, Fabry-Perot Interferometry using white light was selected. This technology exhibits highly desirable feature such as absolute strain measurement, linearity over its full-scale, and temperature compensation. However, experiment results suggest that the resolution is 0.8 micro strain, at best, calibration from one sensor to another can be off by 2.4 - 11.2%, and that temperature compensation is not fully predictable, with errors of up to 3.5 micro strain over an 11C range. Hence, when compared with classic foil gages, FOSG possess less accuracy, similar resolution and repeatability (precision), and superior linearity over their entire operating range. They are immune to EMI and their signals suffer minimal degradation over long distances. It is also expected that drift with time will be minimal in FOSG whereas the gage factor of foil sensors changes over time when exposed to varying environmental conditions. In conclusion, FOSG are "better" than foil gages as long as the application allows calibration of individual units as installed for operation.

  10. Experimental Investigations of Woven Textile Tape as Strain Sensor

    NASA Astrophysics Data System (ADS)

    Kannaian, T.; Naveen, V. S.; Muthukumar, N.; Thilagavathi, G.

    2015-10-01

    In this article, a strain sensitive textile based elastomeric tape sensor has been developed and process parameters for sensor development are optimized. Polyester yarns are used as base threads and rubber threads are used as elastomer for the sensor development. The sensor has been developed with the help of narrow width tape loom by introducing the silver coated nylon yarn in the middle of the tape structure. The influence of weave structure, number of conductive threads and rubber thread tension on sensor development has been optimized by using the Box-Behnken method and the results are analyzed using the Design expert software. From the results, it is found that six numbers of conductive threads in a plain weave structure with rubber thread tension of 750 g is suitable for the sensor to give high gauge factor of 1.626.

  11. Experimental Evaluation of the Pathogenicity of Different Strains of Schistosoma mansoni.

    PubMed

    Euzébio, Antônio Aurélio; Zuim, Nádia Regina Borim; Linhares, Arício Xavier; Magalhães, Luiz Augusto; Zanotti-Magalhães, Eliana Maria

    2012-01-01

    The pathogenesis of three different Schistosoma mansoni strains from the Brazilian states of Minas Gerais (BH strain) and São Paulo (SJ and SD strains) was evaluated in experimentally infected mice. Observations of the most severe clinical cases among local patients treated (SD strain) in the city of Campinas (São Paulo, Brazil) formed the basis of this study. Mice were used as definitive hosts and were infected with cercariae from Biomphalaria tenagophila (SJ and SD strains) and Biomphalaria glabrata (BH strains). The parameters analyzed were as follows: number of S. mansoni eggs in mice feces; number of granulomas per tissue area in liver, spleen, lungs, pancreas, and ascending colon; measurements of hepatic and intestinal granulomas; number of adult worms; and measurements of trematode eggs. The comparison among the three strains indicated that the SD strain, isolated in Campinas, presented a higher worm recovery relative to the number of penetrating cercariae. In addition, when compared to the SJ and BH strains, the SD strain demonstrated similar pathogenicity to the BH strain, with a greater quantity of granulomas in the viscera, as well as larger granulomas and eggs. Furthermore, a greater quantity of trematode eggs was also shed in the feces.

  12. Experimental determination of the strain and strain rate dependence of the fraction of plastic work converted to heat

    SciTech Connect

    Hodowany, J.; Ravichandran, G.; Rosakis, A.J.

    1995-12-31

    When metals are deformed dynamically, there is insufficient time for heat generated by plastic deformation to be conducted to the surroundings. Thus, the conversion of plastic work into heat at high strain rates can result in significant temperature increases, which contribute to thermal softening, thereby altering a material`s constitutive response. The fraction of plastic work converted to heat represents the strength of the coupling term between temperature and mechanical fields in thermalmechanical problems involving plastic flow. The experimental determination of this constitutive function is important since it is an integral part of the formulation of coupled thermomechanical field equations. This fraction also plays an important role in failure mode characterization for metals deforming at high rates of strain, such as the formation of adiabatic shear bands. This investigation systematically examines the rate of conversion of plastic work to heat in metals under dynamic loading. Temperature was measured in-situ using an array of high speed In-Sb infrared detectors. The plastic work rate and the heat generation rate were determined directly from experimental data. The ratio of heat generation rate to plastic work rate, i.e., the relative rate at which plastic work is converted to heat, was calculated from this data. The functional dependence of this quantity upon strain and strain rate is reported for 1020 steel, 2024 aluminum, Ti-6Al-4V titanium alloy, and C300 maraging steel.

  13. Amorphous material in high strain experimental fault gouges

    SciTech Connect

    Yund, R.A.; Blanpied, M.L.; Tullis, T.E.; Weeks, J.D. )

    1990-09-10

    The microstructures of gouges produced in room temperature, rotary shear sliding experiments were examined by transmission electron microscopy. Gouges were produced by sliding on ground surfaces of granite, quartzite, or marble except for one experiment in which a 1-mm-thick simulated gouge layer was used. Water was added to the sliding surfaces of all but one sample. Crystal plastic processes play no role in the granite and quartzite gouges and a minor role in the marbles. All of the gouges consist of mostly submicron crystalline fragments; in addition, the granite gouges contain 5-60% amorphous material, and the quartzite gouge contains {approximately}50% amorphous material. In the granite samples the composition of the amorphous material commonly lies between K-rich and Na, Ca-rich feldspars, although portions may be silica-rich. The microstructural relations suggest that the amorphous material forms by comminution of fragments rather than by melting. The amount of amorphous material increases, and the size of the largest crystalline fragments decreases, with an increase in average shear strain, although the microstructure is nearly uniform throughout each granite gouge layer. These observations suggest that after slip becomes localized on Y shear surfaces and/or R{sub 1} Riedel shears the entire gouge layer must continue to undergo deformation. It is suggested that cyclic deformation in the gouge must occur to accommodate the passage of geometric irregularities on the active slip surfaces.

  14. Study of shrinkage-strain and contraction rates of commercial and experimental compomers.

    PubMed

    Latorre-García, Mariana; Alvarez-Gayosso, Carlos; Barceló-Santana, Federico; Vera-Graziano, Ricardo

    2006-11-01

    To asses the contraction rate and shrinkage-strain of a new experimental compomer in comparison with four commercial compomers and a flowable composite resin. Shrinkage-strain and contraction rate were calculated by measuring the deflection of a disc in a developed instrument using "bonded disk" method. Both shrinkage-strain and contraction rate are reported. Total shrinkage-strain for compomer systems varies from 2.59 to 3.34%, whereas the flowable composite resin showed a value of 3.50%. The contraction rate for compomers varies from 81.60 to 109.80 microm/min, whereas the flowable composite resin obtained 141.6 microm/min. Commercial compomers show a lower contraction rate than the control group, whereas the experimental group only shows statistical differences with a commercial compomer (Dyract AP). The shrinkage-strain and contraction rate results for the experimental compomer are as good as those obtained for a commercial flowable compomer and a flowable composite resin. The contraction rates of all compomers could be directly related to polymerization rates. The method used to measure shrinkage-strain and contraction rate is adequate because it simulates conditions in situ. It can be inferred that the contraction rate is directly related to shrinkage-strain.

  15. Experimental and Numerical Study on Tensile Strength of Concrete under Different Strain Rates

    PubMed Central

    Min, Fanlu; Yao, Zhanhu; Jiang, Teng

    2014-01-01

    The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10−7 s−1 to 10−4 s−1 in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates. PMID:24883355

  16. Experimental and numerical study on tensile strength of concrete under different strain rates.

    PubMed

    Min, Fanlu; Yao, Zhanhu; Jiang, Teng

    2014-01-01

    The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10(-7) s(-1) to 10(-4) s(-1) in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates.

  17. Experimental study of a vortex subjected to imposed strain

    NASA Technical Reports Server (NTRS)

    Panton, Ronald L.; Stifle, Kirk E.

    1991-01-01

    An experimental project was undertaken to investigate the character of vortex breakdown with particular regard to the waveguide theories of vortex breakdown. A rectangular wing based on the NACA 0012 airfoil was used to produce a trailing vortex which convected downstream without undergoing breakdown. Dye marked the vortex location. A disturbance was then introduced onto the vortex using a small moving wire to 'cut' the vortex. The development of upstream and downstream propagating disturbance waves was observed and the propagation velocities measured. The downstream traveling wave produced a structure similar in appearance to a vortex breakdown. The upstream wave produced a moving, swirling, turbulent region that was not a vortex breakdown. The waves moving in either direction have the same swirl velocity profiles but quite different axial velocity profiles. The upstream disturbance (turbulence) moved into a flow with an axial velocity profile that had a wake-like defect in the core region. The downstream moving vortex breakdown moved into a flow with a jet-like overshoot in the core region. The fact that no breakdown was observed for the wake-like defect and breakdown was observed for the jet-like overshoot is not consistent with computational fluid dynamics (CFD) calculations. Although there are not a lot of examples, CFD results show breakdown for both types of profiles. The longitudinal and swirl velocity profiles were documented by Laser Doppler Velocimeter (LDV) measurement. Wave velocities, swirl angles, and swirl parameters are reported.

  18. Schistosoma mansoni experimental infection in Mus spretus (SPRET/EiJ strain) mice

    PubMed Central

    Pérez del Villar, Luis; Vicente, Belén; Galindo-Villardón, Purificación; Castellanos, Andrés; Pérez-Losada, Jesús; Muro, Antonio

    2013-01-01

    Most Schistosoma mansoni experimental infections are developed in several inbred strains of Mus musculus as definitive host. In contrast, Mus spretus is unexplored in Schistosoma infection studies. Mus spretus provides a high variation of immunological phenotypes being an invaluable tool for genetic studies and gene mapping. The aim of this study is to characterize hematological and immunological responses against Schistosoma mansoni infection in Mus spretus (SPRET/EiJ strain) vs. Mus musculus (CD1 strain) mice. Nine weeks after cercarial exposure, animals were perfused and the parasite burden was assessed. The parasitological data suggests that SPRET/EiJ mice tolerate higher parasite loads compared to CD1 strain. In addition, hematological parameters measured in Mus spretus group showed a significant increase in granulocytes population in early stages of infection compared to the CD1 cohort. Meanwhile, CD1 presented higher levels of lymphocytes and IgG1 in the late stages of S. mansoni experimental infection. PMID:23985166

  19. Experimentally induced abutment strains in three types of single-molar implant restorations.

    PubMed

    Seong, W J; Korioth, T W; Hodges, J S

    2000-09-01

    The choice of single-molar implant design is difficult because of a lack of controlled, quantitative biomechanical analyses. This study determined the effect of 3 single-molar implant designs on implant strains under a variety of homologous loading conditions. On each implant abutment, 4 strain gauges were placed axially at 90 degrees to each other on the buccal, lingual, mesial, and distal surfaces. Effects of implant design, load location, direction, and magnitude were tested on axial and bending (buccolingual and mesiodistal) strains of 3 single-molar implant designs: (1) single, 3.75-mm (regular) diameter implant, (2) single, 5-mm (wide) diameter implant, and (3) two 3.75-mm diameter (double) implants connected through a single-molar crown. Results were analyzed with ANOVA. Variations in loading conditions induced 3-dimensionally complex abutment strains on the tested implant designs. Peak absolute strains in mesiodistal direction were 6493 microepsilon for design 1 and 3958 microepsilon on design 2, and 3160 microepsilon in buccolingual direction on design 3. For all loading conditions, the single 3.75-mm diameter implant consistently experienced the largest strains compared with wide-diameter and double implant designs. Changes in centric contact location affected implant abutment strains differently among the 3 designs. Angulated force direction resulted in larger bending strains. For single-molar implant designs, an increase in implant number and diameter may effectively reduce experimental implant abutment strains.

  20. Experimental infection of specific pathogen free piglets with French strains of Streptococcus suis capsular type 2.

    PubMed Central

    Berthelot-Hérault, F; Cariolet, R; Labbé, A; Gottschalk, M; Cardinal, J Y; Kobisch, M

    2001-01-01

    A standardized model of Streptococcus suis type 2 infection in specific-pathogen-free piglets, housed in high-security barns, was used to compare the virulence of 3 French field strains of S. suis serotype 2 isolated from tonsils of a healthy pig (strain 65) or from diseased pigs (meningitis, strain 166', or septicemia, strain 24). In one of the 2 trials, 7-week-old pigs, in 3 groups of 8, were inoculated intravenously with 2 x 10(8) colony-forming units of S. suis type 2. In each group, 1 uninfected animal was a sentinel. Eight animals were also used as negative control group. The experiment was repeated under similar conditions with strains 65 and 166'. Virulence differed markedly among these S. suis strains when clinical signs, zootechnical performances, lesions, and bacteriological data were analyzed. Strain 65 did not induce clinical signs in inoculated pigs. In contrast, pigs infected with the other 2 strains exhibited clinical signs and typical lesions of S. suis type 2 infections. Differences in virulence were also observed between the 2 virulent strains. Sentinel animals exhibited the same manifestations as those recorded in inoculated piglets. Results were similar in the second trial, indicating that under the present experimental conditions, results were reproducible. The standardized conditions described in this study could be a useful tool to further study about the S. suis infection. PMID:11480526

  1. An ultrastructural study of the effect of treatment with atovaquone in brains of mice chronically infected with the ME49 strain of Toxoplasma gondii.

    PubMed Central

    Ferguson, D. J.; Huskinson-Mark, J.; Araujo, F. G.; Remington, J. S.

    1994-01-01

    The morphological effects of drug treatment with atovaquone in the brains of mice chronically infected with Toxoplasma gondii was examined by light and electron microscopy. As early as 1 and 2 weeks of treatment there appeared to be fewer tissue cysts compared to untreated controls and this reduction was more significant after 4 weeks treatment. There also appeared to be a decrease in the number of inflammatory nodules and the severity of the meningitis. Ultrastructurally, the cysts of both treated and control animals were located within host cells. There was a marked increase in both the number of cysts with lysed bradyzoites and the number of degenerate bradyzoites after 4 weeks treatment. It is probable that the drug is more active against the metabolically active immature bradyzoites than the mature organisms. Drug treatment does not appear to result in rupture of tissue cysts or release of Toxoplasma antigens since there is a reduction rather than an increase in the inflammatory response. This drug may be useful in treating chronic toxoplasmosis since it appears to be active against the bradyzoites reducing the parasite burden (cyst number) without initiating a destructive inflammatory response. Images Figure 1 Figure 2 Figure 3 Figure 4 Figures 5 and 6 Figure 7 Figure 8 PMID:8199003

  2. Strain localization in carbonate rocks experimentally deformed in the ductile field

    NASA Astrophysics Data System (ADS)

    Rybacki, E.; Morales, L. F. G.; Dresen, G.

    2012-04-01

    The deformation of rocks in the Earth's crust is often localized, varying from brittle fault gauges in shallow environments to mylonites in ductile shear zones at greater depth. A number of theoretical, experimental, and field studies focused on the evolution and extend of brittle fault zones, but little is known so far about initiation of ductile shear zones. Strain localization in rocks deforming at high temperature and pressure may be induced by several physical, chemical, or structurally-related mechanisms. We performed simple and pure shear deformation experiments on carbonate rocks containing structural inhomogenities in the ductile deformation regime. The results may help to gain insight into the evolution of high temperature shear zones. As starting material we used cylindrical samples of coarse-grained Carrara marble containing one or two 1 mm thin artificially prepared sheets of fine-grained Solnhofen limestone, which act as soft inclusions under the applied experimental conditions. Length and diameter of the investigated solid and hollow cylinders were 10-20 mm and 10-15 mm, respectively. Samples were deformed in a Paterson-type gas deformation apparatus at 900° C temperature and confining pressures of 300 and 400 MPa. Three samples were deformed in axial compression at a bulk strain rate of 8x10-5 s-1to axial strains between 0.02 and 0.21 and 15 samples were twisted in torsion at a bulk shear strain rate of 2x10-4 s-1 to shear strains between 0.01 and 3.74. At low strain, specimens deformed axially and in torsion show minor strain hardening that is replaced by strain weakening at shear strains in excess of about 0.2. Peak shear stress at the imposed condition is about 20 MPa. Strain localized strongly within the weak inclusions as indicated by inhomogeneous bending of initially straight strain markers on sample jackets. Maximum strain concentration within inclusions with respect to the adjacent matrix was between 4 and 40, depending on total strain and

  3. Experimental amoebic liver abscess in hamsters caused by trophozoites of a Brazilian strain of Entamoeba dispar.

    PubMed

    Guzmán-Silva, Maria Angélica; Santos, Helena Lúcia Carneiro; Peralta, Regina Saramago; Peralta, José Mauro; de Macedo, Heloisa Werneck

    2013-05-01

    It has been claimed that amoebic molecules such as amoebapore, galactose/N-acetyl galactosamine inhibitable lectin, and cysteine proteases are responsible for host tissue destruction and are present in both pathogenic Entamoeba histolytica and non-pathogenic Entamoeba dispar. Some reports have provided evidence that after infection with E. dispar, pathological changes may occur in some humans. The aim of this study was to evaluate E. dispar pathogenicity by comparing it to the pathogenicity of E. histolytica through liver abscesses induced in hamsters. Syrian golden hamsters were challenged by intrahepatic inoculation with the 03C E. dispar strain or with two strains of E. histolytica (HM1:IMSS and EGG) to compare their virulence grades. As control groups, we used bacterial flora and Pavlova's modified medium. Lesions were verified at 1, 3 and 6 days after inoculation. Multiplex Polymerase Chain Reaction was performed to characterize each strain using EdP1/EdP2 and EhP1/EhP2 primers. The EGG and HM1:IMSS E. histolytica strains and 03C E. dispar were able to cause liver lesions. The EGG strain caused extensive hepatic abscesses, and trophozoites were found in the lesions throughout the three periods of study. The HM1:IMSS strain caused smaller abscesses when compared to EGG lesions; however, trophozoites were observed at 1 and 3 days after inoculation. The 03C E. dispar strain caused intermediate abscesses when compared to the others; trophozoites were observed in all periods analyzed. The EGG strain caused progressive evolution of the injury, which differed from the HM1:IMSS and 03C strains. These results strongly suggest that the 03C E. dispar strain is pathogenic in the experimental hamster model. Additional studies are necessary to identify potential factors that regulate the manifestation of virulence of this strain and others. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Experimental characterization and modelling of UO2 behavior at high temperatures and high strain rates

    NASA Astrophysics Data System (ADS)

    Salvo, Maxime; Sercombe, Jérôme; Ménard, Jean-Claude; Julien, Jérôme; Helfer, Thomas; Désoyer, Thierry

    2015-01-01

    This work presents an experimental characterization of uranium dioxide (UO2) in compression under Reactivity Initiated Accident (RIA) conditions. Pellet samples were tested at four temperatures (1100, 1350, 1550 and 1700 °C) and at a strain rate varying over 4 decades (10-4-10-3-10-2-10-1 /s). The experimental results show that the stress-strain curves cannot be fitted with a unique power law as it is the case at smaller strain rates (10-9-10-5 /s). A strain-hardening also appears in most of the tests. The microstructural observations show a pronounced evolution of the porosity at the pellet center during the tests. A hyperbolic sine model which accounts for volume variations (pore compressibility) was therefore proposed to describe the behavior of UO2 on a large range of temperatures (1100 - 1700 °C) and strain rates (10-9-10-1 /s). The Finite Element simulations of the compression tests lead to results (maximum stress, axial and hoop strain distribution, porosity distribution) in good agreement with the measurements. The model was then assessed on a database of more than two hundred creep tests.

  5. The experimental evaluation of FBG sensors for strain measurement of prestressed steel strand

    NASA Astrophysics Data System (ADS)

    Li, Enbang; Xi, Jiangtao; Chicharo, Joe F.; Liu, Tiegen; Li, Xin; Jiang, Junfeng; Li, Lina; Wang, Yunxin; Zhang, Yimo

    2005-02-01

    Multi-wire steel strands have been widely used in various prestressed concrete structures. In this study, experimental evaluation of fiber Bragg grating (FBG) sensors for strain measurements in a seven-wire prestressed steel strand has been carried out. An installation technique of FBG sensors has been developed to fulfill the special requirements of the prestressed steel strand. The experiment results show that fiber Bragg gratings can represent the overall stress of the prestressed steel strand without being affected by the specific structure of the strand when it is only fixed on one wire. It is also demonstrated that the maximum strain that the FBG sensor can measure is 6260 μɛ, while the prestressed steel strand usually endures the strain greater than 10000 μɛ. This means that an offset of about 4000 μɛ is necessary to measure the maximum strain that the strand could experience in its applications.

  6. Strain Compensation in Single ZnSe/CdSe Quantum Wells: Analytical Model and Experimental Evidence.

    PubMed

    Rieger, Torsten; Riedl, Thomas; Neumann, Elmar; Grützmacher, Detlev; Lindner, Jörg K N; Pawlis, Alexander

    2017-03-08

    The lattice mismatch between CdSe and ZnSe is known to limit the thickness of ZnSe/CdSe quantum wells on GaAs (001) substrates to about 2-3 monolayers. We demonstrate that this thickness can be enhanced significantly by using In0.12Ga0.88As pseudo substrates, which generate alternating tensile and compressive strains in the ZnSe/CdSe/ZnSe layers resulting in an efficient strain compensation. This method enables to design CdSe/ZnSe quantum wells with CdSe thicknesses ranging from 1 to 6 monolayers, covering the whole visible spectrum. The strain compensation effect is investigated by high resolution transmission electron microscopy and supported by molecular statics simulations. The model approach with the supporting experimental measurements is sufficiently general to be also applied to other highly mismatched material combinations for the design of advanced strained heterostructures.

  7. Growth Parameter of Wild and Selected Strains of Atlantic Salmon (Salmo salar) on Two Experimental Diets

    USDA-ARS?s Scientific Manuscript database

    Atlantic salmon parr from Penobscot (wild) and St. John’s River (selected) strains were cultured in 0.265m3 tanks filled with 2-3 ppt salinity well water and connected to a common bio-filter system. Salmon parr were stocked at 100 fish/tank and fed one of two experimental diets in a 2 x 2 factorial...

  8. Experimental Investigations on Anisotropic Evolution of 304 Stainless Sheets under Tensile Pre-Strains

    NASA Astrophysics Data System (ADS)

    Teng, Lai; Guo, Cheng

    2011-08-01

    The anisotropic evolution of cold rolled 304 stainless steel sheets under pre-strains is investigated experimentally. Uni-axial tensile yield stress and r-value are measured in experiments to represent the anisotropy. The tensile pre-strains under plane stress are achieved by cutting large specimens into small one at different angles to rolling direction. Then the uni-axial tensile tests are performed on the small specimens to investigate the anisotropic evolution. It is found that the yield stress increases with the increase of the pre-strains and decreases with the increase of the angles. However, the changes of r-value are hardly affected by the pre-strains, the small changes of r-value show that the material may remember the rolling direction even after the pre-strains. The sigmoidal shape can be observed in the tensile curves, and its shape depends on the pre-strains and angles. The change of hardening rate can be divided into three stages, and is the most significant at 90° to the rolling direction in the three stages, at the same time the pre-strains cause noncoincidence of the hardening rate curves at the same angle. Moreover, the hardening rate depends on the directions of tensile loading. Second derivative of the hardening rate also can be divided into three stages, and the differences of three stages may mainly be controlled by the different volume fraction of martensite.

  9. Characterization of Saccharomyces cerevisiae strains isolated from must of grape grown in experimental vineyard.

    PubMed

    Cappello, M S; Bleve, G; Grieco, F; Dellaglio, F; Zacheo, G

    2004-01-01

    Isolation and characterization of indigenous Saccharomyces cerevisiae strains from 12 grape varieties grown in an experimental vineyard of Apulia. Thirty to 40 colonies from each of the 12 fermentations were obtained at the end stage of spontaneous fermentation. By using morphological and physiological methods and by the PCR analysis of internal transcribed ITS1-5,8S-ITS2, the isolates belonging to Saccharomyces genus were identified. These isolates were further characterized by amplification with S. cerevisiae species- and delta element-specific primers, thus allowing the identification of S. cerevisiae strains selected from each of the 12 fermentations. By means of RFLP analysis of mtDNA, each S. cerevisiae population isolated from a single fermentation appeared to constitute a genetically homogenous group. The comparison of the 12 cultivar-specific mtDNA RFLP patterns, allowed classifying the 12 S. cerevisiae populations into three genetically homogenous groups. The isolated strains fermented vigorously in synthetic and grape juice medium and showed high alcohol and sulphur dioxide (SO(2)) resistance and low hydrogen sulphite (H(2)S) production. The molecular analysis, in conjunction with the traditional morphological and physiological methods, was useful in discriminating at strain level the indigenous population of S. cerevisiae present in a vineyard of Apulia. The dominant S. cerevisiae strains identified in the 12 fermented musts showed potentially important oenological characteristics. The characterization of natural S. cerevisiae strains from several typical Italian grapes grown in a restricted experimental vineyard is an important step towards the preservation and exploitation of yeast biodiversity of Apulia, a relevant wine-producing region. The close relationship between the S. cerevisiae strains from different grapes grown in the same vineyard indicated that the occurrence of native strains is representative of the area rather than of the variety of

  10. FE and experimental study on how the cortex material properties of synthetic femurs affect strain levels.

    PubMed

    Lopes, Vitor M M; Neto, Maria A; Amaro, Ana M; Roseiro, Luis M; Paulino, M F

    2017-08-01

    The primary aim of this work was to validate the "numerical" cortex material properties (transversely isotropic) of synthetic femurs and to evaluate how the strain level of the cancellous bone can be affected by the FE modeling of the material's behavior. Sensitivity analysis was performed to find out if the parameters of the cortex material affect global strain results more than the Polyurethane (PU) foam used to simulate cancellous bone. Standard 4th generation composite femurs were made with 0.32g/cm(3) solid PU foam to model healthy cancellous bone, while 0.2g/cm(3) cellular PU was used to model unhealthy cancellous bone. Longitudinal and transversal Young's moduli of cortical bone were defined according the manufacturer data, while shear modulus and Poisson's ratios were defined from the literature. All femurs were instrumented with rosette strain gauges and loaded according to ISO7206 standards, simulating a one-legged stance. The experimental results were then compared with those from finite element analysis. When cortical bone was modelled as transversely isotropic, an overall FE/experimental error of 11% was obtained. However, with isotropic material the error rose to 20%. Strain field distributions predicted inside the two bone models were similar, but the strain state of a healthy cancellous bone was much more a compression state than that of unhealthy bone, the compression state decreased about 90%. Strain magnitudes show that average strain-levels of cancellous bone can be significantly affected by the properties of the cortical bone material and, therefore, simulations of femur-implanted systems must account for the composite behavior of the cortex, since small shear strains would develop near isotropic cancellous bone-implant interfaces. Moreover, the authors suggest that changing the volume fraction of glass fibers used to manufacture the cortical bone would allow a more realistic osteoporotic synthetic femurs to be produced. Copyright © 2017 IPEM

  11. 3D Strain Geometry and Crystallographic Fabric in Experimental HT Deformation of Solnhofen Limestone

    NASA Astrophysics Data System (ADS)

    Llana-Funez, S.; Rutter, E. H.

    2003-12-01

    Under conditions where calcite deforms plastically, high temperature deformation tests on Solnhofen limestone have been run using different strain configurations: axi-symmetric shortening and extension, and direct shear. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. In addition to this, we were also able to obtain strain geometries where the vorticity axis in a non-coaxial deformation was either perpendicular to the extension direction (as in simple and sub-simple shear) or parallel to it. In order to keep constant as many parameters as possible, all experiments used the same starting material and the same experimental conditions of temperature 600 \\deg C, confining pressure 200 MPa and comparable strain rates 10-4s-1. At these conditions, and taking into account the special features of Solnhofen limestone (i.e. fine grain size and the presence of impurities preventing grain growth), the predominant deformation mechanism was intracrystalline plasticity. We used pole figures of different calcite lattice elements, measured by electron back-scattered diffraction techniques (EBSD), to characterize the asymmetry of the crystallographic patterns and particularly c-axis pole figures to identify the presence of different fabric components. Further analysis of inverse pole figures in particular experimental directions allowed us to characterize the extension and compression directions of the strain ellipsoid as they geometrically determine the operation of slip systems. Two main aspects can be highlighted from our experimental results. First, it proved particularly useful to combine inverse pole figures with pole figures to characterize not only the shape of the strain ellipsoid in predominantly plastic deformation but also the sense of shear. Second, there is an extraordinary sensitivity of crystal-plastic deformation

  12. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling.

    PubMed

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-28

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10(3) to 10(4) s(-1) using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  13. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    NASA Astrophysics Data System (ADS)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  14. Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations.

    PubMed

    Lee, Bo Mi; Loh, Kenneth J

    2017-04-18

    Carbon nanotubes can be randomly deposited in polymer thin film matrices to form nanocomposite strain sensors. However, a computational framework that enables the direct design of these nanocomposite thin films is still lacking. The objective of this study is to derive an experimentally validated and two-dimensional numerical model of carbon nanotube-based thin film strain sensors. This study consisted of two parts. First, multi-walled carbon nanotube (MWCNT)-Pluronic strain sensors were fabricated using vacuum filtration, and their physical, electrical, and electromechanical properties were evaluated. Second, scanning electron microscope images of the films were used for identifying topological features of the percolated MWCNT network, where the information obtained was then utilized for developing the numerical model. Validation of the numerical model was achieved by ensuring that the area ratios (of MWCNTs relative to the polymer matrix) were equivalent for both the experimental and modeled cases. Strain sensing behavior of the percolation-based model was simulated and then compared to experimental test results.

  15. Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations

    NASA Astrophysics Data System (ADS)

    Lee, Bo Mi; Loh, Kenneth J.

    2017-04-01

    Carbon nanotubes can be randomly deposited in polymer thin film matrices to form nanocomposite strain sensors. However, a computational framework that enables the direct design of these nanocomposite thin films is still lacking. The objective of this study is to derive an experimentally validated and two-dimensional numerical model of carbon nanotube-based thin film strain sensors. This study consisted of two parts. First, multi-walled carbon nanotube (MWCNT)-Pluronic strain sensors were fabricated using vacuum filtration, and their physical, electrical, and electromechanical properties were evaluated. Second, scanning electron microscope images of the films were used for identifying topological features of the percolated MWCNT network, where the information obtained was then utilized for developing the numerical model. Validation of the numerical model was achieved by ensuring that the area ratios (of MWCNTs relative to the polymer matrix) were equivalent for both the experimental and modeled cases. Strain sensing behavior of the percolation-based model was simulated and then compared to experimental test results.

  16. Experimental measurement of the near tip strain field in an iron-silicon single crystal

    NASA Astrophysics Data System (ADS)

    Shield, T. W.; Kim, K.-S.

    1994-05-01

    EXPERIMENTAL RESULTS are presented for the plastic deformation field near a crack (200 μm wide notch) tip in an iron-3% silicon single crystal. The specimen was loaded in four point bending and the measurements were made at zero load after extensive plastic deformation had occurred. Results are given for a crack on the (011) plane with its tip along the [01|T] direction. The surface deformation field was measured using moire microscopy and a grating on the specimen surface. The in-plane Almansi strain components have been obtained by digitally processing the moire fringes. A well-structured asymptotic field has been found at a distance of 350-500 μm from the notch tip, where the maximum plastic strain is about 9%. The asymptotic field is observed to be composed of many distinct angular sectors. Three (six symmetric) of these sectors are found to have approximately constant strains. In a fourth (two symmetric) sector, the surface strains are approximately 1/ r singular. Between these sectors there are interconnecting transition sectors. The location of the stress state on the yield surface and the active slip systems in each sector are identified by assuming that the plastic strain rates are normal to a Schmid law yield surface. The slip systems identified in this manner show excellent agreement with direct observations of the slip texture on the surface and dislocation etch pits in the interior of the specimen. The experimental strain measurements also show that the constant strain sectors are regions in which unloading occurs. Because of this unloading, the crack tip stress and deformation state is substantially different from an HRR type field which assumes proportional loading. This strong nonproportional loading is thought to be caused by the presence of material anisotropy. The nonproportional loading also provides a large amount of crack tip shielding that is evidence of a toughening mechanism that results from the presence of material anisotropy.

  17. Experimental investigation of strains in fabric under biaxial and shear forces.

    NASA Technical Reports Server (NTRS)

    Alley, V. L., Jr.; Faison, R. W.

    1972-01-01

    The paper defines the experimental phase of an objective to obtain the mechanical characteristics and coefficients required by the generalized form of Hooke's law for nylon-polyurethane-coated fabric. Test specimens were cylindrical fabric sleeves and were loaded in axial tension by an Instron, in hoop tension by pressurizing, and in shear by a torquing fixture. An extensive amount of strain data is included for a wide combination of the three membrane loads. The tests indicate highly nonlinear stress-strain characteristics of the fabric and a strong dependency on all three membrane loads.

  18. Virulent Properties of Russian Bovine Viral Diarrhea Virus Strains in Experimentally Infected Calves

    PubMed Central

    Koteneva, Svetlana V.; Semenova, Olga V.; Sergeev, Alexander A.; Titova, Ksenya A.; Morozova, Anastasia A.

    2016-01-01

    The results of experimental study of three noncytopathic and two cytopathic bovine viral diarrhea virus (BVDV) strains isolated from cattle in the Siberian region and belonging to the type 1 (subtypes 1a, 1b, and 1d) have been presented. All investigated strains caused the development of infectious process in the seronegative 4–6-month-old calves after aerosol challenge with the dose of 6 log10 TCID50. The greatest virulence had noncytopathic strain and cytopathic strain related to the subtypes 1d and 1b, respectively. All strains in infected calves caused some signs of moderate acute respiratory disease and diarrhea: depression 3–5 days postinfection (p.i.), refusal to food, severe hyperthermia to 41.9°С, serous exudate discharges from the nasal cavity and eyes, transient diarrhea with blood, leukopenia (up to 2700 cells/mm3), and macroscopic changes in the respiratory organs and intestine. The infected animals recovered from 12 to 15 days p.i. and in 90% cases formed humoral immune response 25 days p.i. (antibody titers to BVDV: 1 : 4–1 : 16). Our results confirmed the presence of virulent BVDV1 strains and showed the need for researches on the molecular epidemiology of the disease, development of more effective diagnostic systems, and optimization of control programs with use of vaccines. PMID:27190687

  19. Experimental studies on the effect of coherency strains on coarsening kinetics: Current status and future outlook

    SciTech Connect

    Muralidharan, G.; Epperson, J.E.; Chen, H.

    1994-03-01

    The effect of coherency strains on the coarsening rate constant in Ostwald ripening is an area that is not well understood. We briefly review the extant experimental data on the effect of coherency strains on coarsening rates and explain the need to account for variations in coarsening rates due to composition and diffusivity effects before drawing any conclusions on the dependence of coarsening rates on the misfit parameter. Using the preexisting theories for coarsening rates in multi-component systems, we suggest a simple method to account for the composition dependence of coarsening rates arising from factors unrelated to coherency strain effects. We then present some of the results from our on-going work in the Ni-Al-Si system and explain the relevance of this study to our understanding of coarsening in internally-stressed systems. We conclude the presentation with our views on the direction of future research in this aspect of coarsening.

  20. Behavior of spinning laminated composite plates with initial twist-experimental vibrations, strain, and deflection results

    NASA Technical Reports Server (NTRS)

    Lapid, A. J.; Kosmatka, J. B.; Mehmed, O.

    1993-01-01

    The experimental behavior of spinning, pre-twisted laminated composite plates was investigated. The purpose of these experiments was to establish an experimental database consisting of strain, deflections, and natural frequencies as a function of rotational velocity. Six different plate sets were tested, that included three different stacking sequences (two symmetric, one asymmetric), two different initial twist levels (0 deg, 30 deg), and two different initial twist axis locations (midchord, quarter-chord). The plates were spin tested at four different combinations of pitch and sweep. It was observed that the location of the pretwist axis and the level of pretwist greatly affects the strain and deflections of the spinning plate, while only the pretwist level affects the measured natural frequencies.

  1. Experimental Validation of FE/BEM Dynamic Strain Model Under Diffuse Acoustic Field Loading

    NASA Technical Reports Server (NTRS)

    Tsoi, W. Ben; Gardner, Bryce; Cotoni, Vincent

    2010-01-01

    Structural finite element (FE) models naturally output displacement or acceleration response data. However, they can also be used to compute stress, internal forces, and strain response. When coupled with a boundary element model (BEM) of the fluid surrounding the structure, a fully coupled analysis can be performed. Modeling a diffuse acoustic field in the BEM fluid provides an excitation like that found when the structure is placed in a reverberation chamber. Fully coupling the structural FE model to the acoustic BEM model provides a means to predict not only the acceleration response of the panel to diffuse field loading, but also the ability to predict the dynamic stress and strain response. This type of model has been available with current predictive tools, but experimental validation of the prediction of dynamic stress or strain is difficult to find. An aluminum panel was instrumented with accelerometers and strain gages and hung in a reverberation room and subjected to a diffuse acoustic field. This paper presents the comparison of the experimental and predicted results.

  2. Numerical and experimental investigation of FBG strain response at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Venkatesan, V. N.; Ramalingam, R.

    2017-02-01

    Strain response of FBG sensors are investigated at various temperatures from 298 K to 4.2 K. Numerical modelling is carried out for acrylate coated, substrate-free fiber Bragg grating (FBG) sensors at room temperature of 298 K and cryogenic temperatures of 77 K, 10 K and 4.2 K. A 1550 nm Bragg wavelength (λB) FBG sensor is modelled and simulated for applied strain (ε) ranging from 0 to 800 µm/m. The Bragg wavelength shifts (ΔλB) thus obtained are compared with the experimentally investigated values obtained by subjecting the FBG sensor to axial strain, with its sensing part not being bonded to any surface. The MTS25 tensile machine with a cryostat under vacuum conditions (10-4 mbar pressure) is used for the experiments and the required temperatures are maintained using liquid Nitrogen (LN2) and compressed Helium gas (He). The Bragg wavelength shift (ΔλB) versus induced strain (ε) is regressed with a linear polynomial function and the strain sensitivity obtained in both the cases are discussed.

  3. Circular pre-strained dielectric elastomer actuator: modeling, simulation and experimental verification

    NASA Astrophysics Data System (ADS)

    Wissler, Michael; Mazza, Edoardo; Kovacs, Gabor

    2005-05-01

    Reliable models are required for the design and optimization of dielectric elastomer actuators. Thereby knowledge of the constitutive behavior of the elastomer is of crucial importance. In this work a pre-strained circular actuator made of a dielectric elastomer is investigated: constitutive models based on uniaxial data are verified by comparing calculation results with experimental observations. An analytical model is derived for the instantaneous response to an activation voltage in the pre-strained circular actuator and a finite element (FE) model is used to simulate the time dependent behavior. Hyperelastic models are used and three strain energy formulations (Yeoh, Ogden and Mooney-Rivlin) are compared in their predictive capabilities. The results of the calculations with the three strain energy forms differ significantly, although all forms were successfully fitted to the same uniaxial data set. Predictions of the actuator behavior based on the Yeoh form agree to a great extent with measurements of the response at different pre-strain levels and activation voltages.

  4. The mass normalization of the displacement and strain mode shapes in a strain experimental modal analysis using the mass-change strategy

    NASA Astrophysics Data System (ADS)

    Kranjc, Tadej; Slavič, Janko; Boltežar, Miha

    2013-12-01

    The classic experimental modal analysis (EMA) is a well-known procedure for determining the modal parameters. The less frequently used strain EMA is based on a response measurement using strain sensors. The results of a strain EMA are the modal parameters, where in addition to the displacement mode shapes the strain mode shapes are also identified. The strain EMA can be used for an experimental investigation of a stress-strain distribution without the need to build a dynamical model. It can also be used to determine the modal parameters when, during modal testing, a motion sensor cannot be used and so a strain sensor is used instead. The displacement and strain mode shapes that are determined with the strain EMA are not mass normalized (scaled with respect to the orthogonality properties of the mass-normalized modal matrix), and therefore some dynamical properties of the system cannot be obtained. The mass normalization can be made with the classic EMA, which requires the use of a motion sensor. In this research a new approach to the mass normalization in the strain EMA, without using a motion sensor, is presented. It is based on the recently introduced mass-change structural modification method, which is used for the mass normalization in an operational modal analysis. This method was modified in such a way that it can be used for the mass normalization in the strain EMA. The mass-normalized displacement and strain mode shapes were obtained using a combination of the proposed approach and the strain EMA. The proposed approach was validated on real structures (beam and plate).

  5. Hyperinducibility of Ia antigen on astrocytes correlates with strain-specific susceptibility to experimental autoimmune encephalomyelitis

    SciTech Connect

    Massa, P.T.; ter Meulen, V.; Fontana, A.

    1987-06-01

    In search of a phenotypic marker determining genetically controlled susceptibility to delayed-type hypersensitivity (DTH) reactions in the brain-in particular, experimental autoimmune encephalomyelitis (EAE)- the authors have compared the ..gamma..-interferon (IFN-..gamma..) induction of Ia molecules on astrocytes and macrophages from rat and mouse strains that are susceptible or resistant to this disease. They focused on Ia expression because DTH reactions to self or foreign antigens are largely mediated by lymphocytes restricted by class II (Ia) antigens of the major histocompatibility complex (MHC). The data demonstrate that Lewis (fully susceptible) and Brown Norway (BN) (fully resistant) rats are very different in that Lewis astrocytes express much higher levels of Ia than BN astrocytes. Similar data were obtained from an analysis of EAE-susceptible and -resistant mouse strains (SJL and BALB/c, respectively), which suggest that this phenomenon may be universal and not limited to only one mammalian species. At least one gene responsible for Ia hyperinduction is located outside the rat RT-1 or the mouse MHC locus. Animals congenic at the RT-1 or MHC locus of the resistant strain but with background genes of the susceptible strain exhibit intermediate levels of Ia compared to fully resistant and susceptible rodents, which fits well with the reduced EAE susceptibility of these congenic animals. Furthermore, hyperinduction of Ia is astrocyte specific, since peritoneal macrophages of susceptible and resistant strains exhibit identical profiles of Ia induction. Thus, astrocyte Ia hyperinducibility may be a major strain- and tissue-specific factor that contributes to Ia-restricted DTH reactions in the brain.

  6. Experimental infection with Brazilian Newcastle disease virus strain in pigeons and chickens

    PubMed Central

    Carrasco, Adriano de Oliveira Torres; Seki, Meire Christina; Benevenute, Jyan Lucas; Ikeda, Priscila; Pinto, Aramis Augusto

    2016-01-01

    This study was designed with the goal of adding as much information as possible about the role of pigeons (Columba livia) and chickens (Gallus gallus) in Newcastle disease virus epidemiology. These species were submitted to direct experimental infection with Newcastle disease virus to evaluate interspecies transmission and virus-host relationships. The results obtained in four experimental models were analyzed by hemagglutination inhibition and reverse transcriptase polymerase chain reaction for detection of virus shedding. These techniques revealed that both avian species, when previously immunized with a low pathogenic Newcastle disease virus strain (LaSota), developed high antibody titers that significantly reduced virus shedding after infection with a highly pathogenic Newcastle disease virus strain (São Joao do Meriti) and that, in chickens, prevent clinical signs. Infected pigeons shed the pathogenic strain, which was not detected in sentinel chickens or control birds. When the presence of Newcastle disease virus was analyzed in tissue samples by RT-PCR, in both species, the virus was most frequently found in the spleen. The vaccination regimen can prevent clinical disease in chickens and reduce viral shedding by chickens or pigeons. Biosecurity measures associated with vaccination programs are crucial to maintain a virulent Newcastle disease virus-free status in industrial poultry in Brazil. PMID:26887250

  7. Experimental infection with Brazilian Newcastle disease virus strain in pigeons and chickens.

    PubMed

    Carrasco, Adriano de Oliveira Torres; Seki, Meire Christina; Benevenute, Jyan Lucas; Ikeda, Priscila; Pinto, Aramis Augusto

    2016-01-01

    This study was designed with the goal of adding as much information as possible about the role of pigeons (Columba livia) and chickens (Gallus gallus) in Newcastle disease virus epidemiology. These species were submitted to direct experimental infection with Newcastle disease virus to evaluate interspecies transmission and virus-host relationships. The results obtained in four experimental models were analyzed by hemagglutination inhibition and reverse transcriptase polymerase chain reaction for detection of virus shedding. These techniques revealed that both avian species, when previously immunized with a low pathogenic Newcastle disease virus strain (LaSota), developed high antibody titers that significantly reduced virus shedding after infection with a highly pathogenic Newcastle disease virus strain (São Joao do Meriti) and that, in chickens, prevent clinical signs. Infected pigeons shed the pathogenic strain, which was not detected in sentinel chickens or control birds. When the presence of Newcastle disease virus was analyzed in tissue samples by RT-PCR, in both species, the virus was most frequently found in the spleen. The vaccination regimen can prevent clinical disease in chickens and reduce viral shedding by chickens or pigeons. Biosecurity measures associated with vaccination programs are crucial to maintain a virulent Newcastle disease virus-free status in industrial poultry in Brazil.

  8. Experimental and numerical analysis of HPTE on mechanical properties of materials and strain distribution

    NASA Astrophysics Data System (ADS)

    Omranpour, B.; Kulagin, R.; Ivanisenko, Y.; Garcia Sanchez, E.

    2017-05-01

    High Pressure Torsion Extrusion (HPTE) is a novel technique which has been recently introduced to the society of Nano-SPD researchers. HPTE exploits the deformation mechanics of HPT but in a larger scale within rod-shape samples and is capable of applying high values of strain to materials in one pass. This research aims to evaluate the effect of HPTE on mechanical properties of materials and also to study the effect of geometry of HPTE die on strain distribution in deformed samples by using Finite Element Method (FEM). Commercial pure Aluminium AA1050 was used for experimental work; and eccentric dies with parallel-misaligned channels were developed for evaluation by numerical modelling. Results of this research will help us better understand the effect of process parameters and also geometry of the die on materials.

  9. An experimental study on stress-strain behavior and constitutive model of hardfill material

    NASA Astrophysics Data System (ADS)

    Wu, Mengxi; Du, Bin; Yao, Yuancheng; He, Xianfeng

    2011-11-01

    Hardfill is a new type of artificially cemented material for dam construction works, with a wide application prospect. Its mechanical behavior lies between concrete and rockfill materials. A series of large-scale triaxial tests are performed on hardfill specimens at different ages, and the stress-strain behavior of hardfill is further discussed. The strength and stress-strain relationship of hardfill materials show both frictional mechanism and cohesive mechanism. An age-related constitutive model of hardfill is developed, which is a parallel model consisting of two components, rockfill component and cementation component. Moreover, a comparison is made between the simulated and the experimental results, which shows that the parallel model can reflect the mechanical characteristics of both rockfill-like nonlinearity and concrete-like age relativity. In addition, a simplified method for the determination of parameters is proposed.

  10. Pathobiology of aging mice and GEM: background strains and experimental design.

    PubMed

    Brayton, C F; Treuting, P M; Ward, J M

    2012-01-01

    The use of induced and spontaneous mutant mice and genetically engineered mice (and combinations thereof) to study cancers and other aging phenotypes to advance improved functional human life spans will involve studies of aging mice. Genetic background contributes to pathology phenotypes and to causes of death as well as to longevity. Increased recognition of expected phenotypes, experimental variables that influence phenotypes and research outcomes, and experimental design options and rationales can maximize the utility of genetically engineered mice (GEM) models to translational research on aging. This review aims to provide resources to enhance the design and practice of chronic and longevity studies involving GEM. C57BL6, 129, and FVB/N strains are emphasized because of their widespread use in the generation of knockout, transgenic, and conditional mutant GEM. Resources are included also for pathology of other inbred strain families, including A, AKR, BALB/c, C3H, C57L, C58, CBA, DBA, GR, NOD.scid, SAMP, and SJL/J, and non-inbred mice, including 4WC, AB6F1, Ames dwarf, B6, 129, B6C3F1, BALB/c,129, Het3, nude, SENCAR, and several Swiss stocks. Experimental strategies for long-term cross-sectional and longitudinal studies to assess causes of or contributors to death, disease burden, spectrum of pathology phenotypes, longevity, and functional healthy life spans (health spans) are compared and discussed.

  11. Experimental Clocking of Nanomagnets with Strain for Ultralow Power Boolean Logic.

    PubMed

    D'Souza, Noel; Salehi Fashami, Mohammad; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2016-02-10

    Nanomagnetic implementations of Boolean logic have attracted attention because of their nonvolatility and the potential for unprecedented overall energy-efficiency. Unfortunately, the large dissipative losses that occur when nanomagnets are switched with a magnetic field or spin-transfer-torque severely compromise the energy-efficiency. Recently, there have been experimental reports of utilizing the Spin Hall effect for switching magnets, and theoretical proposals for strain induced switching of single-domain magnetostrictive nanomagnets, that might reduce the dissipative losses significantly. Here, we experimentally demonstrate, for the first time that strain-induced switching of single-domain magnetostrictive nanomagnets of lateral dimensions ∼200 nm fabricated on a piezoelectric substrate can implement a nanomagnetic Boolean NOT gate and steer bit information unidirectionally in dipole-coupled nanomagnet chains. On the basis of the experimental results with bulk PMN-PT substrates, we estimate that the energy dissipation for logic operations in a reasonably scaled system using thin films will be a mere ∼1 aJ/bit.

  12. Experimental Observations on a Low Strain Counter-Flow Diffusion Flame: Flow and Bouyancy Effects

    NASA Technical Reports Server (NTRS)

    Sutula, J. A.; Torero, J. L.; Ezekoye, O. A.

    1999-01-01

    Diffusion flames are of great interest in fire safety and many industrial processes. The counter-flow configuration provides a constant strain flow, and therefore is ideal to study the structure of diffusion flames. Most studies have concentrated on the high velocity, high strain limit, since buoyantly induced instabilities will disintegrate the planar flame as the velocity decreases. Only recently, experimental studies in microgravity conditions have begun to explore the low strain regimes. Numerical work has shown the coupling between gas phase reaction rates, soot reaction rates, and radiation. For these programs, size, geometry and experimental conditions have been chosen to keep the flame unaffected by the physical boundaries. When the physical boundaries can not be considered infinitely far from the reaction zone discrepancies arise. A computational study that includes boundary effects and accounts for the deviations occurring when the major potential flow assumptions are relaxed was presented by Borlik et al. This development properly incorporates all heat loss terms and shows the possibility of extinction in the low strain regime. A major constraint of studying the low strain regime is buoyancy. Buoyant instabilities have been shown to have a significant effect on the nature of reactants and heat transport, and can introduce instabilities on the flow that result in phenomena such as flickering or fingering. The counter-flow configuration has been shown to provide a flame with no symmetry disrupting instabilities for inlet velocities greater than 50 mm/s. As the velocity approaches this limit, the characteristic length of the experiment has to be reduced to a few millimetres so as to keep the Rayleigh number (Ra(sub L) = (Beta)(g(sub 0))(L(exp 3) del T)/(alpha(v))) below 2000. In this work, a rectangular counter-flow burner was used to study a two-dimensional counter-flow diffusion flame. Flow visualisation and Particle Image Velocimetry served to describe

  13. Experimental Observations on a Low Strain Counter-Flow Diffusion Flame: Flow and Bouyancy Effects

    NASA Technical Reports Server (NTRS)

    Sutula, J. A.; Torero, J. L.; Ezekoye, O. A.

    1999-01-01

    Diffusion flames are of great interest in fire safety and many industrial processes. The counter-flow configuration provides a constant strain flow, and therefore is ideal to study the structure of diffusion flames. Most studies have concentrated on the high velocity, high strain limit, since buoyantly induced instabilities will disintegrate the planar flame as the velocity decreases. Only recently, experimental studies in microgravity conditions have begun to explore the low strain regimes. Numerical work has shown the coupling between gas phase reaction rates, soot reaction rates, and radiation. For these programs, size, geometry and experimental conditions have been chosen to keep the flame unaffected by the physical boundaries. When the physical boundaries can not be considered infinitely far from the reaction zone discrepancies arise. A computational study that includes boundary effects and accounts for the deviations occurring when the major potential flow assumptions are relaxed was presented by Borlik et al. This development properly incorporates all heat loss terms and shows the possibility of extinction in the low strain regime. A major constraint of studying the low strain regime is buoyancy. Buoyant instabilities have been shown to have a significant effect on the nature of reactants and heat transport, and can introduce instabilities on the flow that result in phenomena such as flickering or fingering. The counter-flow configuration has been shown to provide a flame with no symmetry disrupting instabilities for inlet velocities greater than 50 mm/s. As the velocity approaches this limit, the characteristic length of the experiment has to be reduced to a few millimetres so as to keep the Rayleigh number (Ra(sub L) = (Beta)(g(sub 0))(L(exp 3) del T)/(alpha(v))) below 2000. In this work, a rectangular counter-flow burner was used to study a two-dimensional counter-flow diffusion flame. Flow visualisation and Particle Image Velocimetry served to describe

  14. Experimental infection of two South American reservoirs with four distinct strains of Trypanosoma cruzi

    PubMed Central

    Roellig, Dawn M.; McMillan, Katherine; Ellis, Angela E.; Vandeberg, John L.; Champagne, Donald E.; Yabsley, Michael J.

    2010-01-01

    SUMMARY Trypanosoma cruzi (Tc), the causative agent of Chagas disease, is a diverse species with 2 primary genotypes, TcI and TcII, with TcII further subdivided into 5 subtypes (IIa–e). This study evaluated infection dynamics of 4 genetically and geographically diverse T. cruzi strains in 2 South American reservoirs, degus (Octodon degus) and grey short-tailed opossums (Monodelphis domestica). Based on prior suggestions of a genotype-host association, we hypothesized that degus (placental) would more readily become infected with TcII strains while short-tailed opossums (marsupial) would be a more competent reservoir for a TcI strain. Individuals (n = 3) of each species were intraperitoneally inoculated with T. cruzi trypomastigotes of TcIIa [North America (NA)-raccoon (Procyon lotor) origin], TcI [NA-Virginia opossum (Didelphis virginiana)], TcIIb [South America (SA)-human], TcIIe (SA-Triatoma infestans), or both TcI and TcIIa. Parasitaemias in experimentally infected degus peaked earlier (7–14 days post-inoculation (p.i.)) compared with short-tailed opossums (21–84 days p.i.). Additionally, peak parasitaemias were higher in degus; however, the duration of detectable parasitaemias for all strains, except TcIIa, was greater in short-tailed opossums. Infections established in both host species with all genotypes, except for TcIIa, which did not establish a detectable infection in short-tailed opossums. These results indicate that both South American reservoirs support infections with these isolates from North and South America; however, infection dynamics differed with host and parasite strain. PMID:20128943

  15. Experimental infection of adult Scapharca broughtonii with Ostreid herpesvirus SB strain.

    PubMed

    Bai, Chang-Ming; Wang, Qing-Chen; Morga, Benjamin; Shi, Jie; Wang, Chong-Ming

    2017-02-01

    We investigated the susceptibility of ark shell, Scapharca broughtonii, adults to Ostreid herpesvirus SB strain (OsHV-1-SB) through experimental infection by intramuscular injection assays. Results showed the onset of mortality occurred at 3days post injection, one day after the water turbidity became evident in rearing tanks. The mortality curves for the challenged group were similar to those observed at affected hatcheries. Histological lesions, herpesvirus-like particles and high OsHV-1-SB quantities were detected in challenged ark shells. This is the first study to successfully reproduce OsHV-1 disease in Arcoida species, and very few studies in adult bivalves (over 24months old).

  16. Draft Genome Sequences of Two Strains of Salmonella enterica Serovar Typhimurium Displaying Different Virulence in an Experimental Chicken Model

    PubMed Central

    Blais, Burton; Huang, Hongsheng; Wang, Linru; Elmufti, Mohamed; Allain, Ray; Hazelwood, Jennifer; Grenier, Chris; Amoako, Kingsley; Savic, Mirjana; Fattahi Ghazi, Nashmil

    2017-01-01

    ABSTRACT Salmonella enterica serovar Typhimurium strains 22495 and 22792, obtained from wild birds, were found to display different virulence attributes in an experimental chicken model. Closed genome sequences were assembled after sequencing with the Roche 454 and Illumina MiSeq platforms. An additional plasmid was present in the more virulent strain 22495. PMID:28183752

  17. Pathogenicity of different strains of Histophilus somni in the experimental induction of ovine epididymitis.

    PubMed

    Díaz-Aparicio, Efrén; Tenorio-Gutiérrez, Víctor R; Arellano-Reynoso, Beatriz; Enríquez-Verdugo, Idalia; Aguilar-Romero, Francisco

    2009-04-01

    The purpose of this study was to determine any differences in pathogenicity when sheep are experimentally infected with different Histophilus somni isolates: a) 2336 bovine origin strain; b) an isolate from ram orchitis and epididymitis; c) an isolate from the brain of a sheep with neurological signs; d) an isolate from the vagina of a clinically healthy ewe. A total of 20 rams divided in groups of 5 animals each were inoculated in the epididymis with 1 x 10(7) CFU/mL of H. somni; a negative control group of 5 rams was used. All groups inoculated with H. somni showed some epididymitis, but the most pathology was caused by the epididymitis isolate, followed by the vaginal isolate. It was demonstrated that there is a difference in experimental infection capacity among isolates from different origins, as epididymitis occurred and the bacteria was recovered only from groups inoculated with isolates originating from epididymitis and vaginal exudate.

  18. Strain-related effects of fenbendazole treatment on murine experimental autoimmune encephalomyelitis.

    PubMed

    Ramp, A A; Hall, C; Orian, J M

    2010-07-01

    Parasitic infections are a concern in animal facilities, in view of their influence on physiological processes and the immune status of animals. Pinworms are effectively controlled with the anthelminthic fenbendazole (FBZ, [5-(phenylthio)-1H-benzamidazol-2-yl]carbamic acid methyl ester; C(15)H(13)N(3)O(2)S); however, questions remain as to whether prolonged FBZ exposure alters the disease course in specific experimental models, such as those pertaining to the immune system. We report that a three-month regimen of FBZ-medicated feed severely affected the onset and disease severity of murine experimental autoimmune encephalomyelitis (EAE), a disease that mimics multiple sclerosis. Differences were recorded between mouse strains used. Our data suggest that where the use of FBZ is mandatory, its full effect should be verified on the particular EAE variant adopted by the laboratory.

  19. Experimental Measurement and Computational Simulation of the Strains on a Single Yarn in a Kevlar Fabric During Stretching

    DTIC Science & Technology

    2010-06-01

    displacement and strain time histories matched reasonably well with the experimental data. 15. SUBJECT TERMS Photogrammetry strain measurements optical...and textile composites. For instance, Lomov et al. (1, 2) studied the in-plane deformation of yarns in a fabric that underwent shearing using two...sensitivity of the friction coefficient between yarns under a static stretching condition. 2. Experimental Method We used a 5x5 plain- weave Kevlar

  20. Virulence Differences among Melissococcus plutonius Strains with Different Genetic Backgrounds in Apis mellifera Larvae under an Improved Experimental Condition

    PubMed Central

    Nakamura, Keiko; Yamazaki, Yuko; Shiraishi, Akiyo; Kobayashi, Sota; Harada, Mariko; Yoshiyama, Mikio; Osaki, Makoto; Okura, Masatoshi; Takamatsu, Daisuke

    2016-01-01

    European foulbrood (EFB) caused by Melissococcus plutonius is an important bacterial disease of honeybee larvae. M. plutonius strains can be grouped into three genetically distinct groups (CC3, CC12 and CC13). Because EFB could not be reproduced in artificially reared honeybee larvae by fastidious strains of CC3 and CC13 previously, we investigated a method to improve experimental conditions using a CC3 strain and found that infection with a potassium-rich diet enhanced proliferation of the fastidious strain in larvae at the early stage of infection, leading to the appearance of clear clinical symptoms. Further comparison of M. plutonius virulence under the conditions revealed that the representative strain of CC12 was extremely virulent and killed all tested bees before pupation, whereas the CC3 strain was less virulent than the CC12 strain, and a part of the infected larvae pupated. In contrast, the tested CC13 strain was avirulent, and as with the non-infected control group, most of the infected brood became adult bees, suggesting differences in the insect-level virulence among M. plutonius strains with different genetic backgrounds. These strains and the improved experimental infection method to evaluate their virulence will be useful tools for further elucidation of the pathogenic mechanisms of EFB. PMID:27625313

  1. Genetic Vaccination against Experimental Infection with Myotropic Parasite Strains of Trypanosoma cruzi

    PubMed Central

    Araújo, Adriano Fernando; de Oliveira, Gabriel; Vasconcelos, Juliana Fraga; Ersching, Jonatan; Dominguez, Mariana Ribeiro; Vasconcelos, José Ronnie; Machado, Alexandre Vieira; Gazzinelli, Ricardo Tostes; Bruna-Romero, Oscar; Soares, Milena Botelho; Rodrigues, Mauricio Martins

    2014-01-01

    In earlier studies, we reported that a heterologous prime-boost regimen using recombinant plasmid DNA followed by replication-defective adenovirus vector, both containing Trypanosoma cruzi genes encoding trans-sialidase (TS) and amastigote surface protein (ASP) 2, provided protective immunity against experimental infection with a reticulotropic strain of this human protozoan parasite. Herein, we tested the outcome of genetic vaccination of F1 (CB10XBALB/c) mice challenged with myotropic parasite strains (Brazil and Colombian). Initially, we determined that the coadministration during priming of a DNA plasmid containing the murine IL-12 gene improved the immune response and was essential for protective immunity elicited by the heterologous prime-boost regimen in susceptible male mice against acute lethal infections with these parasites. The prophylactic or therapeutic vaccination of resistant female mice led to a drastic reduction in the number of inflammatory infiltrates in cardiac and skeletal muscles during the chronic phase of infection with either strain. Analysis of the electrocardiographic parameters showed that prophylactic vaccination reduced the frequencies of sinus arrhythmia and atrioventricular block. Our results confirmed that prophylactic vaccination using the TS and ASP-2 genes benefits the host against acute and chronic pathologies caused by T. cruzi and should be further evaluated for the development of a veterinary or human vaccine against Chagas disease. PMID:25061263

  2. Design, Evaluation and Experimental Effort Toward Development of a High Strain Composite Wing for Navy Aircraft

    NASA Technical Reports Server (NTRS)

    Bruno, Joseph; Libeskind, Mark

    1990-01-01

    This design development effort addressed significant technical issues concerning the use and benefits of high strain composite wing structures (Epsilon(sub ult) = 6000 micro-in/in) for future Navy aircraft. These issues were concerned primarily with the structural integrity and durability of the innovative design concepts and manufacturing techniques which permitted a 50 percent increase in design ultimate strain level (while maintaining the same fiber/resin system) as well as damage tolerance and survivability requirements. An extensive test effort consisting of a progressive series of coupon and major element tests was an integral part of this development effort, and culminated in the design, fabrication and test of a major full-scale wing box component. The successful completion of the tests demonstrated the structural integrity, durability and benefits of the design. Low energy impact testing followed by fatigue cycling verified the damage tolerance concepts incorporated within the structure. Finally, live fire ballistic testing confirmed the survivability of the design. The potential benefits of combining newer/emerging composite materials and new or previously developed high strain wing design to maximize structural efficiency and reduce fabrication costs was the subject of subsequent preliminary design and experimental evaluation effort.

  3. Experimental measurement of lattice strain pole figures using synchrotron x rays

    NASA Astrophysics Data System (ADS)

    Miller, M. P.; Bernier, J. V.; Park, J.-S.; Kazimirov, A.

    2005-11-01

    This article describes a system for mechanically loading test specimens in situ for the determination of lattice strain pole figures and their evolution in multiphase alloys via powder diffraction. The data from these experiments provide insight into the three-dimensional mechanical response of a polycrystalline aggregate and represent an extremely powerful material model validation tool. Relatively thin (0.5mm) iron/copper specimens were axially strained using a mechanical loading frame beyond the macroscopic yield strength of the material. The loading was halted at multiple points during the deformation to conduct a diffraction experiment using a 0.5×0.5mm2 monochromatic (50keV) x ray beam. Entire Debye rings of data were collected for multiple lattice planes ({hkl}'s) in both copper and iron using an online image plate detector. Strain pole figures were constructed by rotating the loading frame about the specimen transverse direction. Ideal powder patterns were superimposed on each image for the purpose of geometric correction. The chosen reference material was cerium (IV) oxide powder, which was spread in a thin layer on the downstream face of the specimen using petroleum jelly to prevent any mechanical coupling. Implementation of the system at the A2 experimental station at the Cornell High Energy Synchrotron Source (CHESS) is described. The diffraction moduli measured at CHESS were shown to compare favorably to in situ data from neutron-diffraction experiments conducted on the same alloys.

  4. Experimental measurement of lattice strain pole figures using synchrotron x rays

    SciTech Connect

    Miller, M.P.; Bernier, J.V.; Park, J.-S.; Kazimirov, A.

    2005-11-15

    This article describes a system for mechanically loading test specimens in situ for the determination of lattice strain pole figures and their evolution in multiphase alloys via powder diffraction. The data from these experiments provide insight into the three-dimensional mechanical response of a polycrystalline aggregate and represent an extremely powerful material model validation tool. Relatively thin (0.5 mm) iron/copper specimens were axially strained using a mechanical loading frame beyond the macroscopic yield strength of the material. The loading was halted at multiple points during the deformation to conduct a diffraction experiment using a 0.5x0.5 mm{sup 2} monochromatic (50 keV) x ray beam. Entire Debye rings of data were collected for multiple lattice planes ({l_brace}hkl{r_brace}'s) in both copper and iron using an online image plate detector. Strain pole figures were constructed by rotating the loading frame about the specimen transverse direction. Ideal powder patterns were superimposed on each image for the purpose of geometric correction. The chosen reference material was cerium (IV) oxide powder, which was spread in a thin layer on the downstream face of the specimen using petroleum jelly to prevent any mechanical coupling. Implementation of the system at the A2 experimental station at the Cornell High Energy Synchrotron Source (CHESS) is described. The diffraction moduli measured at CHESS were shown to compare favorably to in situ data from neutron-diffraction experiments conducted on the same alloys.

  5. Experimental Results of High Pressure and High Strain Rate Tantalum Flow Stress on Omega and NIF

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Arsenlis, A.; Barton, N.; Benedetti, L.; Huntington, C.; McNaney, J.; Orlikowski, D.; Prisbrey, S.; Remington, B.; Rudd, R.; Swift, D.; Weber, S.; Wehrenberg, C.; Comley, A.

    2015-11-01

    Understanding the high pressure, high strain rate plastic deformation dynamics of materials is an area of research of high interest to planetary formation dynamics, meteor impact dynamics, and inertial confinement fusion designs. Developing predictive theoretical and computational descriptions of such systems, however, has been a difficult undertaking. We have performed many experiments on Omega, LCLS and NIF to test Ta strength models at high pressures (~ up to 4 Mbar), high strain rates (~ 107 s-1) and high strains (>30%) under ramped compression conditions using Rayleigh-Taylor and Richtmyer-Meshkov instability properties. These experiments use plasma drive to ramp compress the sample to higher pressure without shock-melting. We also studied lattice level strength mechanisms under shocked compression using a diffraction-based technique. Our studies show that the strength mechanisms from macro to micro scales are different from the traditional strength model predictions and that they are loading path dependent. We will report the experimental results. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  6. Experimental method to characterize the strain dependent permeability of tissue engineering scaffolds.

    PubMed

    Nasrollahzadeh, Naser; Pioletti, Dominique P

    2016-11-07

    Permeability is an overarching mechanical parameter encompassing the effects of porosity, pore size, and interconnectivity of porous structures. This parameter directly influences transport of soluble particles and indirectly regulates fluid pressure and velocity in tissue engineering scaffolds. The permeability also contributes to the viscoelastic behavior of visco-porous material under loading through frictional drag mechanism. We propose a straightforward experimental method for permeability characterization of tissue engineering scaffolds. In the developed set-up a step-wise spacer was designed to facilitate measurement of the permeability under different compressive strains while maintaining similar experimental conditions during the successive measurements. As illustration of the method, we measured the permeability of scaffolds presenting different average pore sizes and subjected to different compression values. Results showed an exponential relationship between the permeability and the average pore size of the scaffolds. Furthermore, the trend of the permeability decrease with compressive strains was depending on pore sizes of the scaffolds. The permeability also appeared to play a role in relaxation behavior of the scaffolds.

  7. Scleral Permeability Varies by Mouse Strain and Is Decreased by Chronic Experimental Glaucoma

    PubMed Central

    Pease, Mary E.; Oglesby, Ericka N.; Cone-Kimball, Elizabeth; Jefferys, Joan L.; Steinhart, Matthew R.; Kim, Anthony J.; Hanes, Justin; Quigley, Harry A.

    2014-01-01

    Purpose. To determine differences in scleral permeability, as measured by diffusion of macromolecules, by using fluorescence recovery after photobleaching (FRAP), with reference to differences by mouse strain, scleral region, and the effect of experimental glaucoma. Methods. In three mouse strains (B6, CD1, and B6 mice with mutation in collagen 8α2 [Aca23]), we used FRAP to measure the diffusion of fluorescein isothiocyanate–dextran, molecular weight 40 kDa, into a photobleached zone of sclera. Scleral regions near the optic nerve head (peripapillary) and two successively more anterior regions were compared. Sclera from mouse eyes subjected to chronically elevated intraocular pressure after bead injection into the anterior chamber were compared to fellow eye controls. FRAP data were compared against estimated retinal ganglion cell axon loss in glaucomatous eyes. Results. Diffusion rates of dextran molecules in the sclera were significantly greater in Aca23 and B6 mice than in CD1 mice in a multivariate model adjusted for region and axial length (P < 0.0001). Dextran diffusion significantly decreased in glaucomatous eyes, and the decline increased with greater axon loss (P = 0.0003, multivariable model). Peripapillary scleral permeability was higher in CD1 than B6 and Aca23 mice (P < 0.05, multivariable model, adjusted by Bonferroni). Conclusions. Measurement of the diffusion rates of dextran molecules in the sclera showed that glaucoma leads to decreased scleral permeability in all three mouse strains tested. Among mouse strains tested, those that were more susceptible to glaucomatous loss of retinal ganglion cells had a lower scleral permeability at baseline. PMID:24557355

  8. An experimental study on the mechanical properties of rat brain tissue using different stress-strain definitions.

    PubMed

    Karimi, Alireza; Navidbakhsh, Mahdi

    2014-07-01

    There are different stress-strain definitions to measure the mechanical properties of the brain tissue. However, there is no agreement as to which stress-strain definition should be employed to measure the mechanical properties of the brain tissue at both the longitudinal and circumferential directions. It is worth knowing that an optimize stress-strain definition of the brain tissue at different loading directions may have implications for neuronavigation and surgery simulation through haptic devices. This study is aimed to conduct a comparative study on different results are given by the various definitions of stress-strain and to recommend a specific definition when testing brain tissues. Prepared cylindrical samples are excised from the parietal lobes of rats' brains and experimentally tested by applying load on both the longitudinal and circumferential directions. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are used to determine the elastic modulus, maximum stress and strain. The highest non-linear stress-strain relation is observed for the Almansi-Hamel strain definition and it may overestimate the elastic modulus at different stress definitions at both the longitudinal and circumferential directions. The Green-St. Venant strain definition fails to address the non-linear stress-strain relation using different definitions of stress and triggers an underestimation of the elastic modulus. The results suggest the application of the true stress-true strain definition for characterization of the brain tissues mechanics since it gives more accurate measurements of the tissue's response using the instantaneous values.

  9. Comparative evaluation of two vaccine candidates against experimental leishmaniasis due to Leishmania major infection in four inbred mouse strains.

    PubMed

    Benhnini, Fouad; Chenik, Mehdi; Laouini, Dhafer; Louzir, Hechmi; Cazenave, Pierre André; Dellagi, Koussay

    2009-11-01

    Experimental leishmaniasis in BALB/c and C57BL/6 mice are the most investigated murine models that were used for the preclinical evaluation of Leishmania vaccine candidates. We have previously described two new inbred mouse strains named PWK and MAI issued from feral founders that also support the development of experimental leishmaniasis due to L. major. In this study, we sought to determine whether different mouse inbred strains generate concordant or discordant results when used to evaluate the potential of Leishmania proteins to protect against experimental leishmaniasis. To this end, two Leishmania proteins, namely, LACK (for Leishmania homolog of receptor for activated C kinase) and LmPDI (for L. major protein disulfide isomerase) were compared for their capacity to protect against experimental leishmaniasis in PWK, MAI, BALB/c, and C57BL/6 inbred mouse strains. Our data show that the capacity of Leishmania proteins to confer protection depends on the mouse strain used, stressing the important role played by the genetic background in shaping the immune response against the pathogen. These results may have important implications for the preclinical evaluation of candidate Leishmania vaccines: rather than using a single mouse strain, a panel of different inbred strains of various genetic backgrounds should be tested in parallel. The antigen that confers protection in the larger range of inbred strains may have better chances to be also protective in outbred human populations and should be selected for clinical trials.

  10. Prediction of the Strain Response of Poly-AlN/(100)Si Surface Acoustic Wave Resonator and Experimental Analysis

    PubMed Central

    Chen, Shuo; You, Zheng

    2016-01-01

    The strain sensitivity of the Aluminum Nitride (AlN)/Silicon (Si) surface acoustic wave resonator (SAWR) is predicted based on a modeling method introduced in this work, and further compared with experimental results. The strain influence on both the period of the inter-digital transducer (IDT) and the sound velocity is taken into consideration when modeling the strain response. From the modeling results, AlN and Si have opposite responses to strain; hence, for the AlN/Si-based SAWR, both a positive and a negative strain coefficient factor can be achieved by changing the thickness of the AlN layer, which is confirmed by strain response testing based on a silicon cantilever structure with two AlN configurations (1 μm and 3 μm in thickness, respectively). PMID:27128922

  11. Experimental infection of duck origin virulent Newcastle disease virus strain in ducks.

    PubMed

    Dai, Yabin; Cheng, Xu; Liu, Mei; Shen, Xinyue; Li, Jianmei; Yu, Shengqing; Zou, Jianmin; Ding, Chan

    2014-07-17

    Newcastle disease (ND) caused by virulent Newcastle disease virus (NDV) is an acute, highly contagious and fatal viral disease affecting most species of birds. Ducks are generally considered to be natural reservoirs or carriers of NDV while being resistant to NDV strains, even those most virulent for chickens; however, natural ND cases in ducks have been gradually increasing in recent years. In the present study, ducks of different breeds and ages were experimentally infected with duck origin virulent NDV strain duck/Jiangsu/JSD0812/2008 (JSD0812) by various routes to investigate the pathogenicity of NDV in ducks. Six breeds (mallard, Gaoyou, Shaoxing, Jinding, Shanma, and Pekin ducks) were infected intramuscularly (IM) with JSD0812 strain at the dose of 5 × 108 ELD50. Susceptibility to NDV infection among breeds varied, per morbidity and mortality. Mallard ducks were the most susceptible, and Pekin ducks the most resistant. Fifteen-, 30-, 45-, 60-, and 110-day-old Gaoyou ducks were infected with JSD0812 strain at the dose of 5 × 108 ELD50 either IM or intranasally (IN) and intraocularly (IO), and their disease development, viral shedding, and virus tissue distribution were determined. The susceptibility of ducks to NDV infection decreased with age. Most deaths occurred in 15- and 30-day-old ducklings infected IM. Ducks infected IN and IO sometimes exhibited clinical signs, but seldom died. Clinical signs were primarily neurologic. Infected ducks could excrete infectious virus from the pharynx and/or cloaca for a short period, which varied with bird age or inoculation route; the longest period was about 7 days. The rate of virus isolation in tissues from infected ducks was generally low, even in those from dead birds, and it appeared to be unrelated to bird age and infection route. The results confirmed that some of the naturally occurring NDV virulent strains can cause the disease in ducks, and that ducks play an important role in the epidemiology of ND. The

  12. Experimental infection of duck origin virulent Newcastle disease virus strain in ducks

    PubMed Central

    2014-01-01

    Background Newcastle disease (ND) caused by virulent Newcastle disease virus (NDV) is an acute, highly contagious and fatal viral disease affecting most species of birds. Ducks are generally considered to be natural reservoirs or carriers of NDV while being resistant to NDV strains, even those most virulent for chickens; however, natural ND cases in ducks have been gradually increasing in recent years. In the present study, ducks of different breeds and ages were experimentally infected with duck origin virulent NDV strain duck/Jiangsu/JSD0812/2008 (JSD0812) by various routes to investigate the pathogenicity of NDV in ducks. Results Six breeds (mallard, Gaoyou, Shaoxing, Jinding, Shanma, and Pekin ducks) were infected intramuscularly (IM) with JSD0812 strain at the dose of 5 × 108 ELD50. Susceptibility to NDV infection among breeds varied, per morbidity and mortality. Mallard ducks were the most susceptible, and Pekin ducks the most resistant. Fifteen-, 30-, 45-, 60-, and 110-day-old Gaoyou ducks were infected with JSD0812 strain at the dose of 5 × 108 ELD50 either IM or intranasally (IN) and intraocularly (IO), and their disease development, viral shedding, and virus tissue distribution were determined. The susceptibility of ducks to NDV infection decreased with age. Most deaths occurred in 15- and 30-day-old ducklings infected IM. Ducks infected IN and IO sometimes exhibited clinical signs, but seldom died. Clinical signs were primarily neurologic. Infected ducks could excrete infectious virus from the pharynx and/or cloaca for a short period, which varied with bird age or inoculation route; the longest period was about 7 days. The rate of virus isolation in tissues from infected ducks was generally low, even in those from dead birds, and it appeared to be unrelated to bird age and infection route. Conclusions The results confirmed that some of the naturally occurring NDV virulent strains can cause the disease in ducks, and that ducks play an important

  13. Prediction of Sinorhizobium meliloti sRNA genes and experimental detection in strain 2011

    PubMed Central

    Valverde, Claudio; Livny, Jonathan; Schlüter, Jan-Philip; Reinkensmeier, Jan; Becker, Anke; Parisi, Gustavo

    2008-01-01

    Background Small non-coding RNAs (sRNAs) have emerged as ubiquitous regulatory elements in bacteria and other life domains. However, few sRNAs have been identified outside several well-studied species of gamma-proteobacteria and thus relatively little is known about the role of RNA-mediated regulation in most other bacterial genera. Here we have conducted a computational prediction of putative sRNA genes in intergenic regions (IgRs) of the symbiotic α-proteobacterium S. meliloti 1021 and experimentally confirmed the expression of dozens of these candidate loci in the closely related strain S. meliloti 2011. Results Our first sRNA candidate compilation was based mainly on the output of the sRNAPredictHT algorithm. A thorough manual sequence analysis of the curated list rendered an initial set of 18 IgRs of interest, from which 14 candidates were detected in strain 2011 by Northern blot and/or microarray analysis. Interestingly, the intracellular transcript levels varied in response to various stress conditions. We developed an alternative computational method to more sensitively predict sRNA-encoding genes and score these predicted genes based on several features to allow identification of the strongest candidates. With this novel strategy, we predicted 60 chromosomal independent transcriptional units that, according to our annotation, represent strong candidates for sRNA-encoding genes, including most of the sRNAs experimentally verified in this work and in two other contemporary studies. Additionally, we predicted numerous candidate sRNA genes encoded in megaplasmids pSymA and pSymB. A significant proportion of the chromosomal- and megaplasmid-borne putative sRNA genes were validated by microarray analysis in strain 2011. Conclusion Our data extend the number of experimentally detected S. meliloti sRNAs and significantly expand the list of putative sRNA-encoding IgRs in this and closely related α-proteobacteria. In addition, we have developed a computational

  14. Prediction of Sinorhizobium meliloti sRNA genes and experimental detection in strain 2011.

    PubMed

    Valverde, Claudio; Livny, Jonathan; Schlüter, Jan-Philip; Reinkensmeier, Jan; Becker, Anke; Parisi, Gustavo

    2008-09-16

    Small non-coding RNAs (sRNAs) have emerged as ubiquitous regulatory elements in bacteria and other life domains. However, few sRNAs have been identified outside several well-studied species of gamma-proteobacteria and thus relatively little is known about the role of RNA-mediated regulation in most other bacterial genera. Here we have conducted a computational prediction of putative sRNA genes in intergenic regions (IgRs) of the symbiotic alpha-proteobacterium S. meliloti 1021 and experimentally confirmed the expression of dozens of these candidate loci in the closely related strain S. meliloti 2011. Our first sRNA candidate compilation was based mainly on the output of the sRNAPredictHT algorithm. A thorough manual sequence analysis of the curated list rendered an initial set of 18 IgRs of interest, from which 14 candidates were detected in strain 2011 by Northern blot and/or microarray analysis. Interestingly, the intracellular transcript levels varied in response to various stress conditions. We developed an alternative computational method to more sensitively predict sRNA-encoding genes and score these predicted genes based on several features to allow identification of the strongest candidates. With this novel strategy, we predicted 60 chromosomal independent transcriptional units that, according to our annotation, represent strong candidates for sRNA-encoding genes, including most of the sRNAs experimentally verified in this work and in two other contemporary studies. Additionally, we predicted numerous candidate sRNA genes encoded in megaplasmids pSymA and pSymB. A significant proportion of the chromosomal- and megaplasmid-borne putative sRNA genes were validated by microarray analysis in strain 2011. Our data extend the number of experimentally detected S. meliloti sRNAs and significantly expand the list of putative sRNA-encoding IgRs in this and closely related alpha-proteobacteria. In addition, we have developed a computational method that proved useful

  15. Analysis and experimental study on the strain transfer mechanism of an embedded basalt fiber-encapsulated fiber Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenglin; Wang, Yuan; Sun, Yangyang; Zhang, Qinghua; You, Zewei; Huang, Xiaodi

    2017-01-01

    The precision of the encapsulated fiber optic sensor embedded into a host suffers from the influences of encapsulating materials. Furthermore, an interface transfer effect of strain sensing exists. This study uses an embedded basalt fiber-encapsulated fiber Bragg grating (FBG) sensor as the research object to derive an expression in a multilayer interface strain transfer coefficient by considering the mechanical properties of the host material. The direct impact of the host material on the strain transfer at an embedded multipoint continuous FBG (i.e., multiple gratings written on a single optical fiber) monitoring strain sensor, which was self-developed and encapsulated with basalt fiber, is studied to present the strain transfer coefficients corresponding to the positions of various gratings. The strain transfer coefficients of the sensor are analyzed based on the experiments designed for this study. The error of the experimental results is ˜2 μɛ when the strain is at 60 μɛ and below. Moreover, the measured curves almost completely coincide with the theoretical curves. The changes in the internal strain field inside the embedded structure of the basalt fiber-encapsulated FBG strain sensor could be easily monitored. Hence, important references are provided to measure the internal stress strain of the sensor.

  16. Tissue tropism and parasite burden of Toxoplasma gondii RH strain in experimentally infected mice.

    PubMed

    Dadimoghaddam, Yousef; Daryani, Ahmad; Sharif, Mehdi; Ahmadpour, Ehsan; Hossienikhah, Zahra

    2014-07-01

    To evaluate parasite distribution and tissue tropism of Toxoplasma gondii tachyzoites in experimentally infected mice using real time QPCR. In this survey 16 Balb/c mice were inoculated with 1 × 10(4) alive tachyzoites of Toxoplasma gondii RH strain. After 1, 2, 3 days post infection and the last day (before death), different tissues of mice including blood, brain, eye, liver, spleen, kidney, heart and muscle were harvested. Following tissues DNA extraction, the parasite burden was quantified using real time QPCR targeting the B1 gene (451 bp). It showed that Toxoplasma after intraperitoneal injection was able to movement to various tissues in 24 hours. Parasite burden was high in all tissues but the most number of parasites were observed in kidney, heart and liver, respectively. These data provide significant baseline information about Toxoplasma pathogenesis, vaccine monitoring and drug efficiency. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  17. EXPERIMENTAL TESTS OF VANADIUM STRENGTH MODELS AT HIGH PRESSURES AND STRAIN RATES

    SciTech Connect

    Park, H; Barton, N R; Becker, R C; Bernier, J V; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Rudd, R E

    2010-03-02

    Experimental results showing significant reductions from classical in the Rayleigh-Taylor (RT) instability growth rate due to high pressure material strength or effective lattice viscosity in metal foils are presented. On the Omega Laser in the Laboratory for Laser Energetics, University of Rochester, target samples of polycrystalline vanadium are compressed and accelerated quasi-isentropically at {approx}1 Mbar pressures, while maintaining the samples in the solid-state. Comparison of the results with constitutive models for solid state strength under these conditions show that the measured RT growth is substantially lower than predictions using existing models that work well at low pressures and long time scales. High pressure, high strain rate data can be explained by the enhanced strength due to a phonon drag mechanism, creating a high effective lattice viscosity.

  18. Experimental Observations of Localization Phenomena in Sands: Plane Strain Versus Triaxial Compression Conditions

    NASA Technical Reports Server (NTRS)

    Alshibli, Khalid A.; Batiste, Susan N.; Sture, Stein; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A comprehensive experimental investigation was conducted to investigate the effects of loading condition and confining pressure on strength properties and instability phenomena in sands. A uniform sub-rounded to rounded natural silica sand known as F-75 Ottawa sand was used in the investigation. The results of a series on Conventional Triaxial Compression (CTC) experiments tested under very low confining pressures (0.05 - 1.30) kPa tested in a Microgravity environment abroad the NASA Space Shuttle are presented in addition to the results similar specimens tested in terrestrial laboratory to investigate the effect of confining pressure on the constitutive behavior of sands. The behavior of the CTC experiments is compared with the results of Plane Strain (PS) experiments. Computed tomography and other digital imaging techniques were used to study the development and evolution of shear bands.

  19. Detailed analysis of an experimental challenge model for Leishmania infantum (JPC strain) in dogs.

    PubMed

    Poot, Jacqueline; Rogers, Matthew E; Bates, Paul A; Vermeulen, Arno

    2005-06-10

    In this study, disease progression after intravenous or subdermal infection of dogs with Leishmania infantum JPC strain was monitored. A challenge performed on 14 dogs via the intravenous route with 5 x 10(7) stationary phase promastigotes of the L. infantum JPC strain was 100% successful. During a follow up period of 1.5 years, several parameters were evaluated in order to find the most reliable disease markers. Parasite detection by culture and histology were found to be very sensitive (100%). Additionally, regular physical examination, serology and serum gamma-globulin levels were found to be useful parameters in the evaluation of disease severity and are recommended for inclusion in vaccination-challenge experiments. Although this intravenous challenge model has practical limitations, the data set confirms it is the best experimental model currently available for vaccine development. Two intravenously infected dogs were treated with corticosteroids for 5 months. This treatment was shown to enhance all aspects of a Leishmania infection. Five more dogs were infected by sub-dermal injection of promastigotes mixed with a proteophosphoglycan-matrix (PSG) secreted by Leishmania that assists in transmission and infection by sand fly bite. The resulting parasite burdens were low and the animals remained asymptomatic during a 2-year follow up period. However, this procedure did result in infection in 80% of the dogs and is appealing for future development as a natural challenge model in vaccine development.

  20. Experimental deformation of partially molten granite and implications for strain localization

    NASA Astrophysics Data System (ADS)

    Goncalves, L.; Hirth, G.; Alkmim, F.; Pedrosa-Soares, A.; Goncalves, C.

    2011-12-01

    To improve our understanding of partially molten systems we conducted a set of hydrostatic, general shear and axial compression experiments on sintered aggregates composed of equal amounts by weight of quartz, albite and microcline (grain size of 37-53μm). All experiments were conducted using a Griggs solid medium apparatus at T=900°C, P=1.5GPa and strain rates from 10-4/s to 10-6/s. Previous hydrostatic and axial compression experiments conducted on partial molten granitic rocks have shown that the initial grain size, amount of melt and strain rate are important parameters for the development of distinct microstructures, LPO, and melt distribution. In addition, some of these studies demonstrated that the strength of granite and aplite decrease significantly for melt contents up to 15%, when compared to similar melt-free rocks. The rock's strength deep within the Earth decreases owing to partial melting which brings up some questions: would strain localization take place when partial melt affects rheology? Would brittle and/or ductile shear zones act as potential regions for concentration of partial melt? Is there a critical fraction of melt responsible for strain localization? How is melt distribution influenced by deformation? How does the kinematics of deformation (i.e., axial compression versus general shear) affect melt distribution? The purpose of our experiments is to investigate the role of melting on the rheological properties of crustal rocks. In addition, we seek to provide new constraints on the grain scale processes that control the properties of partially molten rocks and the importance of these processes in understanding shear localization in the lithosphere. Samples were made from crushed Amelia albite (Ab97Or2An1), Hugo Microcline (Or90) and Black Hills quartzite, which have all been used in previous experimental deformation studies. The albite is essentially pure; the microcline contains ~ 1% of muscovite. The Black Hills quartzite contains < 1

  1. Efficacy of one dose vaccination against experimental infection with two Mycoplasma hyopneumoniae strains.

    PubMed

    Michiels, Annelies; Arsenakis, Ioannis; Boyen, Filip; Krejci, Roman; Haesebrouck, Freddy; Maes, Dominiek

    2017-08-29

    Mycoplasma hyopneumoniae (M. hyopneumoniae) is the primary agent of enzootic pneumonia in pigs. Pigs are often infected with different M. hyopneumoniae strains. This study assessed the efficacy of vaccination against experimental infection with two genetically different M. hyopneumoniae strains in weaned piglets. At 33 days of age (D0), 45 M. hyopneumoniae-free piglets were randomly assigned to three different groups: 1) negative control group (NCG; n = 5): not vaccinated, not infected, 2) positive control group (PCG; n = 20): not vaccinated, infected, and 3) vaccination group (VG; n = 20): single vaccination with an inactivated whole-cell M. hyopneumoniae vaccine (Hyogen®, Ceva) (D1), infected. The PCG and VG were endotracheally inoculated with 7 × 10(7) CCU in 7 ml of the highly virulent M. hyopneumoniae strain F7.2C (D24) and 7 × 10(7) CCU in 7 ml low virulent strain F1.12A (D25). A respiratory disease score (RDS) was assessed from D24 until D53. At D53 (euthanasia), macroscopic lung lesions (MLL) were scored, log copies of M. hyopneumoniae DNA (qPCR) and IL-1 and IL-6-concentrations (ELISA) on bronchoalveolar lavage fluid were determined. The RDS and MLL at euthanasia were respectively 0, 1.20 and 0.55 (P < 0.001) and 0, 7.56 and 0.68 (P < 0.001) for NCG, PCG and VG, respectively. The qPCR results for PCG and VG were 3.99 and 1.78 log copies (P < 0.001), respectively, with a significant difference between PCG and VG. The IL-1 and IL-6 results at euthanasia for NCG, PCG and VG were 17.61, 1283.39 and 53.04 pg/ml (P < 0.001) and 148.10, 493.35 and 259.80 pg/ml (P = 0.004), respectively with a significant difference between PCG and VG. Vaccination with Hyogen® in pigs was efficacious against an experimental challenge with both a low and highly virulent M. hyopneumoniae strain as the vaccinated pigs coughed significantly less, and showed significantly less lung lesions compared to the non-vaccinated challenged pigs: the vaccinated

  2. Effect of Saccharomyces cerevisiae strain UFMG A-905 in experimental model of inflammatory bowel disease.

    PubMed

    Tiago, F C P; Porto, B A A; Ribeiro, N S; Moreira, L M C; Arantes, R M E; Vieira, A T; Teixeira, M M; Generoso, S V; Nascimento, V N; Martins, F S; Nicoli, J R

    2015-01-01

    In the present study, the protective potential of Saccharomyces cerevisiae strain UFMG A-905 was evaluated in a murine model of acute ulcerative colitis (UC). Six groups of Balb/c mice were used: not treated with yeast and not challenged with dextran sulphate sodium (DSS) (control); treated with S. cerevisiae UFMG A-905 (905); treated with the non-probiotic S. cerevisiae W303 (W303); challenged with DSS (DSS); treated with S. cerevisiae UFMG A-905 and challenged with DSS (905 + DSS); and treated with S. cerevisiae W303 and challenged with DSS (W303 + DSS). Seven days after induction of UC, mice were euthanised to remove colon for enzymatic, immunological, and histopathological analysis. In vivo intestinal permeability was also evaluated. An improvement of clinical manifestations of experimental UC was observed only in mice of the 905 + DSS group when compared to animals from DSS and W303 + DSS groups. This observation was confirmed by histological and morphometrical data and determination of myeloperoxidase and eosinophil peroxidase activities, intestinal permeability and some pro-inflammatory cytokines. S. cerevisiae UFMG A-905 showed to be a potential alternative treatment for UC when used in an experimental animal model of the disease.

  3. Experimental Transmission of Eastern Equine Encephalitis Virus by Strains of Aedes albopictus and A. taeniorhynchus (Diptera: Culicidae)

    DTIC Science & Technology

    1994-01-01

    AD-A281 335 0 Experimental Transmission of Eastern Equine Encephaliti Vi 4 by Strains of Aedes albopictus and A. taeniorhynch &1j (Diptera: Culicidae...co m •strains of Aedes albopictus (Skuse) was assessed for eastern equine encephalitis (EEE) virus isolated from Ae. albopictus collected in Polk...County, Florida. Both species became infected with and transmitted EEE virus by bite after feeding on 1-d-old chicks that had _been inoculated with EEE

  4. Overcoming unresponsiveness in experimental autoimmune encephalomyelitis (EAE) resistant mouse strains by adoptive transfer and antigenic challenge.

    PubMed

    Shaw, Michael K; Zhao, Xiao-qing; Tse, Harley Y

    2012-04-09

    Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system (CNS) and has been used as an animal model for study of the human demyelinating disease, multiple sclerosis (MS). EAE is characterized by pathologic infiltration of mononuclear cells into the CNS and by clinical manifestation of paralytic disease. Similar to MS, EAE is also under genetic control in that certain mouse strains are susceptible to disease induction while others are resistant. Typically, C57BL/6 (H-2(b)) mice immunized with myelin basic protein (MBP) fail to develop paralytic signs. This unresponsiveness is certainly not due to defects in antigen processing or antigen presentation of MBP, as an experimental protocol described here had been used to induce severe EAE in C57BL/6 mice as well as other reputed resistant mouse strains. In addition, encephalitogenic T cell clones from C57BL/6 and Balb/c mice reactive to MBP had been successfully isolated and propagated. The experimental protocol involves using a cellular adoptive transfer system in which MBP-primed (200 μg/mouse) C57BL/6 donor lymph node cells are isolated and cultured for five days with the antigen to expand the pool of MBP-specific T cells. At the end of the culture period, 50 million viable cells are transferred into naive syngeneic recipients through the tail vein. Recipient mice so treated normally do not develop EAE, thus reaffirming their resistant status, and they can remain normal indefinitely. Ten days post cell transfer, recipient mice are challenged with complete Freund adjuvant (CFA)-emulsified MBP in four sites in the flanks. Severe EAE starts to develop in these mice ten to fourteen days after challenge. Results showed that the induction of disease was antigenic specific as challenge with irrelevant antigens did not induce clinical signs of disease. Significantly, a titration of the antigen dose used to challenge the recipient mice showed that it could be as low as 5

  5. Experimental Study on the Relationship between Hardness and Principal Strain in Tube Hydroforming Process

    NASA Astrophysics Data System (ADS)

    Wang, G. D.; Chan, L. C.

    2009-11-01

    In order to find a feasible method to evaluate the deformation of tubes during the Tube Hydroforming (THF) process, the hardness and the strain in two selected deformation areas of hydro formed copper tubes (C11000) were measured and tested, and an instinct relationship was found between the hardness and the principal strains of the tubes. The major strain of the surface of tubes had the strongest linear relationship with hardness. A regression formula was used to describe the relationship between hardness and the sensitive strain which is defined in the present work as a dependent variable of major strain and thickness strain.

  6. Comparative Analysis of Conventional Natural Killer Cell Responses to Acute Infection with Toxoplasma gondii Strains of Different Virulence

    PubMed Central

    Ivanova, Daria L.; Fatima, Rida; Gigley, Jason P.

    2016-01-01

    Conventional natural killer (cNK) cells, members of group 1 innate lymphoid cells, are a diverse cell subpopulation based on surface receptor expression, maturation, and functional potential. cNK cells are critical for early immunity to Toxoplasma gondii via IFNγ production. Acute cNK cell responses to infection with different strains of T. gondii have not yet been characterized in detail. Here, we comprehensively performed this analysis with Type I virulent RH, Type II avirulent ME49, and fully attenuated Type I cps1-1 strains. In response to these three parasite strains, murine cNK cells produce IFNγ and become cytotoxic and polyfunctional (IFNγ+CD107a+) at the site of infection. In contrast to virulent RH and avirulent ME49 T. gondii strains, attenuated cps1-1 induced only local cNK cell responses. Infections with RH and ME49 parasites significantly decreased cNK cell frequency and numbers in spleen 5 days post infection compared with cps1-1 parasites. cNK cell subsets expressing activating receptors Ly49H, Ly49D, and NKG2D and inhibitory receptors Ly49I and CD94/NKG2A were similar when compared between the strains and at 5 days post infection. cNK cells were not proliferating (Ki67−) 5 days post infection with any of the strains. cNK cell maturation as measured by CD27, CD11b, and KLRG1 was affected after infection with different parasite strains. RH and ME49 infection significantly reduced mature cNK cell frequency and increased immature cNK cell populations compared with cps1-1 infection. Interestingly, KLRG1 was highly expressed on immature cNK cells after RH infection. After RH and ME49 infections, CD69+ cNK cells in spleen were present at higher frequency than after cps1-1 infection, which may correlate with loss of the mature cNK cell population. Cytokine multiplex analysis indicated cNK cell responses correlated with peritoneal exudate cell, spleen, and serum proinflammatory cytokine levels, including IL-12. qPCR analysis of parasite

  7. Performance Analysis and Experimental Validation of the Direct Strain Imaging Method

    Treesearch

    Athanasios Iliopoulos; John G. Michopoulos; John C. Hermanson

    2013-01-01

    Direct Strain Imaging accomplishes full field measurement of the strain tensor on the surface of a deforming body, by utilizing arbitrarily oriented engineering strain measurements originating from digital imaging. In this paper an evaluation of the method’s performance with respect to its operating parameter space is presented along with a preliminary...

  8. Effect of the Escherichia coli EMO strain on experimental infection by Salmonella enterica serovar Typhimurium in gnotobiotic mice.

    PubMed

    Lima-Filho, J V M; Vieira, L Q; Arantes, R M E; Nicoli, J R

    2004-07-01

    An experimental infection with Salmonella enterica subsp. enterica serovar Typhimurium was evaluated in gnotobiotic mice previously exposed to a plasmid-free non-pathogenic Escherichia coli (EMO strain). Mice were exposed to EMO (experimental) or not (control) 10 days before challenge with Salmonella Typhimurium (10(2) colony forming units (CFU)/mouse). Survival after challenge was higher (P < 0.05) in the experimental group (16%) than in the control animals (0%). Histopathological examination of the colon and ileum mucosa of the experimental group showed less extensive lesions such as edema, cell inflammatory infiltration and hyperemia. The epithelial cells of the mucosal surface and the production of the mucous layer were also better preserved in the experimental group. The population levels of Salmonella Typhimurium in the feces were initially 10-fold lower (P < 0.05) in the experimental groups. However, 3 days after challenge both experimental and control groups showed similar population levels ranging from 10(8) to 10(9) CFU/g of feces. The intestinal contents of total and anti-Salmonella Typhimurium sIgA were higher in the experimental groups 10 days after inoculation of E. coli EMO strain. Translocation of Salmonella Typhimurium to the spleen was 10-fold lower (P < 0.05) in the experimental group only on day 3 after infection. This was not related to an increase in the bacterial blood clearance of the animals, as shown by experimental venous challenge with E. coli B41. In conclusion, treatment of mice with E. coli EMO strain promoted a relative protection against experimental infection with Salmonella Typhimurium. This protection was not due to the reduction of the population of pathogens in the intestine but was probably related to stimulation of the immune response.

  9. Experimental infection of Carrion crows (Corvus corone) with two European West Nile virus (WNV) strains.

    PubMed

    Dridi, Maha; Vangeluwe, Didier; Lecollinet, Sylvie; van den Berg, Thierry; Lambrecht, Bénédicte

    2013-07-26

    West Nile virus (WNV) has become a wide-spread arbovirus in Europe and the Mediterranean Basin countries. This emerging zoonotic disease disseminated 13 years ago in North America where its impact on animal and public health has been considerable. Although American corvids have been the most reliable avian sentinels for WN surveillance in the United States, there is so far no data available about the susceptibility of their Western European counterparts to WNV. Clinical follow-up and serum, oral swabs and feathers viral RNA load monitoring was herein performed on wild-caught Carrion crows (Corvus corone) experimentally inoculated with two WNV strains, Is98 that was isolated from a stork in Israel where it elicited high rates of avian deaths in 1998, and Fr2000 which was only associated to sporadic equine cases in Camargue, France in 2000. Inoculated crows were sensitive to both WNV infections and, as expected from the available epidemiological data, Is98 induced a higher mortality rate (100% vs. 33%) and a quicker fatal outcome, with higher viral RNA loads detected in the serum, oral swabs and feathers than in the Fr2000 group. Therefore, Carrion crows should also be a target species for WNV surveillance in Western Europe, where reporting for abnormal mortalities could be completed by viral detection in the herein described avian matrices. These experimental findings also emphasize the peculiarity of the European situation where a large spectrum of WNV genetic and pathotypic variants have been so far isolated despite limited WN disease reports in wild birds. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Experimental Transmission of Leishmania infantum by Two Major Vectors: A Comparison between a Viscerotropic and a Dermotropic Strain

    PubMed Central

    Maia, Carla; Seblova, Veronika; Sadlova, Jovana; Votypka, Jan; Volf, Petr

    2011-01-01

    We quantified Leishmania infantum parasites transmitted by natural vectors for the first time. Both L. infantum strains studied, dermotropic CUK3 and viscerotropic IMT373, developed well in Phlebotomus perniciosus and Lutzomyia longipalpis. They produced heavy late-stage infection and colonized the stomodeal valve, which is a prerequisite for successful transmission. Infected sand fly females, and especially those that transmit parasites, feed significantly longer on the host (1.5–1.8 times) than non-transmitting females. Quantitative PCR revealed that P. perniciosus harboured more CUK3 strain parasites, while in L. longipalpis the intensity of infection was higher for the IMT373 strain. However, in both sand fly species the parasite load transmitted was higher for the strain with dermal tropism (CUK3). All but one sand fly female infected by the IMT373 strain transmitted less than 600 promastigotes; in contrast, 29% of L. longipalpis and 14% of P. perniciosus infected with the CUK3 strain transmitted more than 1000 parasites. The parasite number transmitted by individual sand flies ranged from 4 up to 4.19×104 promastigotes; thus, the maximal natural dose found was still about 250 times lower than the experimental challenge dose used in previous studies. This finding emphasizes the importance of determining the natural infective dose for the development of an accurate experimental model useful for the evaluation of new drugs and vaccines. PMID:21695108

  11. Development of an improved Streptococcus uberis experimental mastitis challenge model using different doses and strains in lactating dairy cows.

    PubMed

    Khazandi, Manouchehr; Eats, Patricia; Trott, Darren; Ebrahimie, Esmaeil; Perry, Jeanette; Hickey, Elizabeth; Page, Stephen; Garg, Sanjay; Petrovski, Kiro R

    2015-11-01

    Developing a reliable mastitis challenge infection model is required to test new intramammary antimicrobial preparations, other novel bovine mastitis treatments, and study mastitis pathogenesis. Three treatment groups of Holstein Friesian cows in active lactation were administered two doses (10(4) and 10(6) cfu/quarter) on a single occasion with one of the three Streptococcus uberis strains (BFR6019, MFF1283 and SA002) suspended in 5 ml of sterile PBS, administered via intramammary inoculation immediately after milking. All quarters that were challenged with S. uberis strains MLF1283 and BFR6019 showed clinical signs of mastitis on day 1 and 2 after the challenge. Strain SA002 had a lower rate of inducing clinical mastitis which was detected later than day 3 after the challenge. We successfully developed a rapid and reliable model for inducing experimental S. uberis mastitis with 100% success rate in cows in active lactation. On the basis of the correlation results between strains, RAPD fingerprinting results, clinical findings, and a 100% success rate of mastitis induction for low and high doses S. uberis strains MLF1283 and BFR6019, strain virulence seems to be a more important effect than challenge dose in induction of clinical mastitis following experimental challenge.

  12. An experimental method to obtain the elastic strain energy function from torsion-tension tests

    NASA Technical Reports Server (NTRS)

    Peng, S. T. J.; Landel, R. F.

    1976-01-01

    It is shown that by employing a torsion-tension test, it is possible to have a complete mapping near the origin of the two principal strain invariants associated with the rate of change of the strain energy function. However, the mathematical representation of the twist moment and normal forces vs strain and the strain energy function are complex. This problem is solved by using a set of solid cylindrical bars with different diameters such that the difference in diameter of two successive bars is small. The stress-strain equations can be grossly oversimplified by considering differences in twist moment and normal force as a function of difference in radius.

  13. Experimental infection of cows with newly isolated Akabane virus strain (AKAV-7) causing encephalomyelitis.

    PubMed

    Lee, Hyeyeoun; Jeong, Hansol; Park, Surim; Yang, Myeon-Sik; Kim, Jongwon; Bae, Jaehyun; Kwon, Yonghwan; Kim, Min-Su; Oem, Jae-Ku; Lee, Myoung-Heon; Lim, Chae-Woong; Kim, Bumseok

    2016-06-10

    Akabane virus (AKAV), an arthropod-transmitted bunyavirus, is a major cause of congenital abnormalities and encephalomyelitis in ruminants. In 2010, there was a major outbreak of encephalomyelitis in Korea and fifteen AKAV strains, including AKAV-7, were isolated from cows. To identify the neuropathogenicity of AKAV-7, we performed experimental infection of cows. Six-month-old female Korean Holstein dairy cattle were inoculated with AKAV-7 by various routes, including intracerebral (IC), intrasubarachnoid space (IS), subcutaneous (SC) and intravenous (IV); a separate group was vaccinated before intravenous infection. Five of the six cows in the IC group and two of the six cows in the IS group showed clinical signs such as locomotor ataxia and paralysis of the hind limbs. Three of six cows died after IC infection 9-12 days post infection (dpi). Histopathologic changes such as nonsuppurative encephalomyelitis were confirmed in various parts of the central nervous system in the IC, IS and SC groups. Early onset of neutralizing antibodies in the serum and lower viral mRNA levels in the peripheral blood mononuclear cells (PBMCs) and various tissues in the vaccinated group was noticeable compared to the unvaccinated group (IV group). We suggest that the AKAV vaccine currently used in Korea may be partially effective for protection against AKAV-7 in cows.

  14. Detection of antibodies against Theiler's murine encephalomyelitis virus GDVII strain in experimental guinea pigs.

    PubMed

    Häger, C; Glage, S; Held, N; Bleich, E M; Burghard, A; Mähler, M; Bleich, André

    2016-10-01

    A disease affecting guinea pigs called 'guinea pig lameness' characterized by clinical signs of depression, lameness of limbs, flaccid paralysis, weight loss and death within a few weeks was first described by Römer in 1911. After a research group in our facility kept laboratory guinea pigs from two different origins together in one room, lameness was observed in two animals. Further investigations revealed a serological immune response against Theiler's murine encephalomyelitis virus (TMEV; GDVII strain) in these animals. Histopathology of the lumbar spinal cord of these animals showed mononuclear cell infiltration and necrotic neurons in the anterior horn. Therefore, all guinea pigs from this contaminated animal unit, from other units in our facility, as well as from different European institutions and breeding centres were screened for antibodies directed against GDVII. Our investigations showed that approximately 80% of all guinea pigs from the contaminated animal unit were seropositive for GDVII, whereas animals from other separate units were completely negative. In addition, 43% of tested sera from the different European institutions and breeding centres contained antibodies against GDVII. The present data confirm that an unknown viral infection causes an immune response in experimental guinea pigs leading to seroconversion against GDVII and that guinea pigs from a commercial breeder are the source of the infection. © The Author(s) 2015.

  15. Regulatory T cells control strain specific resistance to Experimental Autoimmune Prostatitis.

    PubMed

    Breser, Maria L; Lino, Andreia C; Motrich, Ruben D; Godoy, Gloria J; Demengeot, Jocelyne; Rivero, Virginia E

    2016-09-14

    Susceptibility to autoimmune diseases results from the encounter of a complex and long evolved genetic context with a no less complex and changing environment. Major actors in maintaining health are regulatory T cells (Treg) that primarily dampen a large subset of autoreactive lymphocytes escaping thymic negative selection. Here, we directly asked whether Treg participate in defining susceptibility and resistance to Experimental Autoimmune Prostatitis (EAP). We analyzed three common laboratory strains of mice presenting with different susceptibility to autoimmune prostatitis upon immunization with prostate proteins. The NOD, the C57BL/6 and the BALB/c mice that can be classified along a disease score ranging from severe, mild and to undetectable, respectively. Upon mild and transient depletion of Treg at the induction phase of EAP, each model showed an increment along this score, most remarkably with the BALB/c mice switching from a resistant to a susceptible phenotype. We further show that disease associates with the upregulation of CXCR3 expression on effector T cells, a process requiring IFNγ. Together with recent advances on environmental factors affecting Treg, these findings provide a likely cellular and molecular explanation to the recent rise in autoimmune diseases incidence.

  16. Regulatory T cells control strain specific resistance to Experimental Autoimmune Prostatitis

    PubMed Central

    Breser, Maria L.; Lino, Andreia C.; Motrich, Ruben D.; Godoy, Gloria J.; Demengeot, Jocelyne; Rivero, Virginia E.

    2016-01-01

    Susceptibility to autoimmune diseases results from the encounter of a complex and long evolved genetic context with a no less complex and changing environment. Major actors in maintaining health are regulatory T cells (Treg) that primarily dampen a large subset of autoreactive lymphocytes escaping thymic negative selection. Here, we directly asked whether Treg participate in defining susceptibility and resistance to Experimental Autoimmune Prostatitis (EAP). We analyzed three common laboratory strains of mice presenting with different susceptibility to autoimmune prostatitis upon immunization with prostate proteins. The NOD, the C57BL/6 and the BALB/c mice that can be classified along a disease score ranging from severe, mild and to undetectable, respectively. Upon mild and transient depletion of Treg at the induction phase of EAP, each model showed an increment along this score, most remarkably with the BALB/c mice switching from a resistant to a susceptible phenotype. We further show that disease associates with the upregulation of CXCR3 expression on effector T cells, a process requiring IFNγ. Together with recent advances on environmental factors affecting Treg, these findings provide a likely cellular and molecular explanation to the recent rise in autoimmune diseases incidence. PMID:27624792

  17. A numerical and experimental study of temperature effects on deformation behavior of carbon steels at high strain rates

    NASA Astrophysics Data System (ADS)

    Pouya, M.; Winter, S.; Fritsch, S.; F-X Wagner, M.

    2017-03-01

    Both in research and in the light of industrial applications, there is a growing interest in methods to characterize the mechanical behavior of materials at high strain rates. This is particularly true for steels (the most important structural materials), where often the strain rate-dependent material behavior also needs to be characterized in a wide temperature range. In this study, we use the Finite Element Method (FEM), first, to model the compressive deformation behavior of carbon steels under quasi-static loading conditions. The results are then compared to experimental data (for a simple C75 steel) at room temperature, and up to testing temperatures of 1000 °C. Second, an explicit FEM model that captures wave propagation phenomena during dynamic loading is developed to closely reflect the complex loading conditions in a Split-Hopkinson Pressure Bar (SHPB) – an experimental setup that allows loading of compression samples with strain rates up to 104 s-1 The dynamic simulations provide a useful basis for an accurate analysis of dynamically measured experimental data, which considers reflected elastic waves. By combining numerical and experimental investigations, we derive material parameters that capture the strain rate- and temperature-dependent behavior of the C75 steel from room temperature to 1000 °C, and from quasi-static to dynamic loading.

  18. Comparison of abortion and infection after experimental challenge of pregnant bison and cattle with Brucella abortus strain 2308

    USDA-ARS?s Scientific Manuscript database

    A comparative study was conducted using data from naive bison (n=45) and cattle (n=46) from 8 and 6 studies, respectively, in which a standardized Brucella abortus strain 2308 experimental challenge was administered. The incidence of abortion, fetal infection, uterine or mammary infection, or infec...

  19. Probiotic yeasts: Anti-inflammatory potential of various non-pathogenic strains in experimental colitis in mice

    PubMed Central

    Foligné, Benoît; Dewulf, Joëlle; Vandekerckove, Pascal; Pignède, Georges; Pot, Bruno

    2010-01-01

    AIM: To evaluate the in vitro immunomodulation capacity of various non-pathogenic yeast strains and to investigate the ability of some of these food grade yeasts to prevent experimental colitis in mice. METHODS: In vitro immunomodulation was assessed by measuring cytokines [interleukin (IL)-12p70, IL-10, tumor necrosis factor and interferon γ] released by human peripheral blood mononuclear cells after 24 h stimulation with 6 live yeast strains (Saccharomyces ssp.) and with bacterial reference strains. A murine model of acute 2-4-6-trinitrobenzene sulfonic acid (TNBS)-colitis was next used to evaluate the distinct prophylactic protective capacities of three yeast strains compared with the performance of prednisolone treatment. RESULTS: The six yeast strains all showed similar non-discriminating anti-inflammatory potential when tested on immunocompetent cells in vitro. However, although they exhibited similar colonization patterns in vivo, some yeast strains showed significant anti-inflammatory activities in the TNBS-induced colitis model, whereas others had weaker or no preventive effect at all, as evidenced by colitis markers (body-weight loss, macroscopic and histological scores, myeloperoxidase activities and blood inflammatory markers). CONCLUSION: A careful selection of strains is required among the biodiversity of yeasts for specific clinical studies, including applications in inflammatory bowel disease and other therapeutic uses. PMID:20440854

  20. Experimental and Analytical Investigations on Plane Strain Toughness for 7085 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Shuey, R. T.; Barlat, F.; Karabin, M. E.; Chakrabarti, D. J.

    2009-02-01

    Data are presented on plane strain fracture toughness, yield strength, and strain hardening for three orientations of samples from quarter-thickness ( t/4) and midthickness ( t/2) locations of alloy 7085 plates with different gages aged past peak strength with different 2nd step aging times (T7X). These data are fit to an expression adapted from Hahn and Rosenfield (1968), in which toughness is proportional to strain hardening, the square root of yield strength, and the square root of a critical strain ɛ c . Strain-hardening exponent n is replaced by an alternative measure, since the stress-strain data do not follow a power law. With increased overaging, the increase of strain hardening dominates the decrease of strength, such that toughness increases. The critical strain, which represents the influence of the microstructure on toughness, has no trend with overaging time. Constituents and grain boundary precipitates, thought to be the microstructural elements most differentiating alloy 7085 from alloy 7050, are quantified at t/4 and at t/2 on one plate. From this the greater critical strain at t/2 than at t/4 is mainly attributed to greater effective spacing of constituents. Critical strain is also greater with longitudinal loading and crack propagating in the long transverse direction, but definite understanding of this will require better anisotropic fracture mechanics and further microstructural characterization.

  1. Experimental infection of lambs with C and S-type strains of Mycobacterium avium subspecies paratuberculosis: immunological and pathological findings

    PubMed Central

    2014-01-01

    The two main genotypes of recognized isolates of Mycobacterium avium subsp. paratuberculosis (Map) are cattle (C) and sheep (S) strains. An experimental infection was conducted to establish the effect of Map strain on the pathogenesis of ovine paratuberculosis. Twenty-four out of thirty 1.5-month-old Assaf lambs were divided into 4 groups of 6 and infected orally with three low passage field isolates, two of S- (22G and the pigmented Ovicap49) and one of C– (764) type, and the reference K-10 strain (C type). The remaining six animals were unchallenged controls. Animals were euthanized at 150 and 390 days post-infection (dpi). Throughout the experiment, the peripheral immune response was assessed and histological and molecular (PCR) studies were conducted on samples of intestine and related lymphoid tissue. Specific antibody and IFN-γ production was significantly higher in animals infected with the C strains, while no consistent IFN- γ responses were observed in the S-type strain infected groups. A positive intradermal skin test response was detected in all infected groups. Lambs infected with S-type strains had granulomatous lesions restricted to the lymphoid tissue with no differences in the lesion intensity over time. In both C–type strain groups, lesions were more severe at 150 dpi while at 390 dpi lesions, characterized by well-demarcated granulomas with fibrosis, decreased in severity. Only infected lambs were positive to PCR. These results suggest that the strain of Map has a strong influence over the immune and pathological responses developed by the host. Lesions induced by C–type strains in lambs show a regressive character and tend to decrease as the infection progresses. PMID:24428881

  2. Experimental infection of lambs with C and S-type strains of Mycobacterium avium subspecies paratuberculosis: immunological and pathological findings.

    PubMed

    Fernández, Miguel; Benavides, Julio; Sevilla, Iker A; Fuertes, Miguel; Castaño, Pablo; Delgado, Laetitia; García Marín, J Francisco; Garrido, Joseba M; Ferreras, M Carmen; Pérez, Valentín

    2014-01-16

    The two main genotypes of recognized isolates of Mycobacterium avium subsp. paratuberculosis (Map) are cattle (C) and sheep (S) strains. An experimental infection was conducted to establish the effect of Map strain on the pathogenesis of ovine paratuberculosis. Twenty-four out of thirty 1.5-month-old Assaf lambs were divided into 4 groups of 6 and infected orally with three low passage field isolates, two of S- (22G and the pigmented Ovicap49) and one of C- (764) type, and the reference K-10 strain (C type). The remaining six animals were unchallenged controls. Animals were euthanized at 150 and 390 days post-infection (dpi). Throughout the experiment, the peripheral immune response was assessed and histological and molecular (PCR) studies were conducted on samples of intestine and related lymphoid tissue. Specific antibody and IFN-γ production was significantly higher in animals infected with the C strains, while no consistent IFN- γ responses were observed in the S-type strain infected groups. A positive intradermal skin test response was detected in all infected groups. Lambs infected with S-type strains had granulomatous lesions restricted to the lymphoid tissue with no differences in the lesion intensity over time. In both C-type strain groups, lesions were more severe at 150 dpi while at 390 dpi lesions, characterized by well-demarcated granulomas with fibrosis, decreased in severity. Only infected lambs were positive to PCR. These results suggest that the strain of Map has a strong influence over the immune and pathological responses developed by the host. Lesions induced by C-type strains in lambs show a regressive character and tend to decrease as the infection progresses.

  3. Effect of vaccination of pigs against experimental infection with high and low virulence Mycoplasma hyopneumoniae strains.

    PubMed

    Villarreal, I; Maes, D; Vranckx, K; Calus, D; Pasmans, F; Haesebrouck, F

    2011-02-17

    This study investigated the infection pattern and lung lesion development in pigs caused by a low and highly virulent Mycoplasma hyopneumoniae strain at 4 and 8 weeks (w) post infection (PI). It also determined the efficacy of a commercial inactivated whole-cell vaccine against infection with each one of these M. hyopneumoniae strains. Ninety piglets free of M. hyopneumoniae were selected, and 40 of them were randomly vaccinated during their first week of life. At weaning, all piglets were allocated to 10 different groups and housed in pens with absolute filters. At 4 weeks of age, pigs were inoculated intratracheally with either a highly virulent M. hyopneumoniae strain, a low virulent strain or with sterile culture medium. Half of all animals were euthanized at 4 w PI, while the remaining half was euthanized at 8 w PI. Coughing was assessed daily, and lung lesions, immunofluorescence (IF), bacteriological analysis and nested PCR were assessed after necropsy. It was demonstrated that contrary to the highly virulent strain, the low virulent strain required more than 4 weeks PI (commonly accepted as the standard infection model) to reach maximum clinical symptoms. Vaccination significantly reduced clinical symptoms, macroscopic and microscopic lung lesions in pigs infected with the highly virulent strain. This effect was more pronounced at 4 than at 8 weeks PI. Protective efficacy was also observed in pigs infected with the low virulent strain, but the effect was less pronounced than on the highly virulent strain.

  4. Experimental study of a further attenuated live measles vaccine of the Sugiyama strain in Iran

    PubMed Central

    Mirchamsy, H.; Shafyi, A.; Rafyi, M. R.; Bahrami, S.; Nazari, P.; Fatemie, S.

    1974-01-01

    After encouraging results of the mass vaccination programme in Iran, in which 5 million children in rural areas were vaccinated with the Japanese Sugiyama strain at its 82nd passage in baby calf kidney, and a progressive decrease in the incidence of measles as well as a reduction of excessive infant mortality, a further attenuated vaccine, produced with the same strain, cloned in Japan, was compared in a field trial with the parent vaccine. The new strain caused fewer reactions than the original strain. Seroconversion with a geometric mean antibody titre of 6·1 was observed in 95% of susceptible children. PMID:4522721

  5. Strain-specific protective immunity following vaccination against experimental Trypanosoma cruzi infection.

    PubMed

    Haolla, Filipe A; Claser, Carla; de Alencar, Bruna C G; Tzelepis, Fanny; de Vasconcelos, José Ronnie; de Oliveira, Gabriel; Silvério, Jaline C; Machado, Alexandre V; Lannes-Vieira, Joseli; Bruna-Romero, Oscar; Gazzinelli, Ricardo T; dos Santos, Ricardo Ribeiro; Soares, Milena B P; Rodrigues, Mauricio M

    2009-09-18

    Immunisation with Amastigote Surface Protein 2 (asp-2) and trans-sialidase (ts) genes induces protective immunity in highly susceptible A/Sn mice, against infection with parasites of the Y strain of Trypanosoma cruzi. Based on immunological and biological strain variations in T. cruzi parasites, our goal was to validate our vaccination results using different parasite strains. Due to the importance of the CD8(+) T cells in protective immunity, we initially determined which strains expressed the immunodominant H-2K(k)-restricted epitope TEWETGQI. We tested eight strains, four of which elicited immune responses to this epitope (Y, G, Colombian and Colombia). We selected the Colombian and Colombia strains for our studies. A/Sn mice were immunised with different regimens using both T. cruzi genes (asp-2 and ts) simultaneously and subsequently challenged with blood trypomastigotes. Immune responses before the challenge were confirmed by the presence of specific antibodies and peptide-specific T cells. Genetic vaccination did not confer protective immunity against acute infection with a lethal dose of the Colombian strain. In contrast, we observed a drastic reduction in parasitemia and a significant increase in survival, following challenge with an otherwise lethal dose of the Colombia strain. In many surviving animals with late-stage chronic infection, we observed alterations in the heart's electrical conductivity, compared to naive mice. In summary, we concluded that immunity against T. cruzi antigens, similar to viruses and bacteria, may be strain-specific and have a negative impact on vaccine development.

  6. The Brazilian Zika virus strain causes birth defects in experimental models

    PubMed Central

    Cugola, Fernanda R.; Fernandes, Isabella R.; Russo, Fabiele B.; Freitas, Beatriz C.; Dias, João L.M.; Guimarães, Katia P.; Benazzato, Cecília; Almeida, Nathalia; Pignatari, Graciela C.; Romero, Sarah; Polonio, Carolina M.; Cunha, Isabela; Freitas, Carla L.; Brandão, Wesley N.; Rossato, Cristiano; Andrade, David G.; Faria, Daniele de P.; Garcez, Alexandre T.; Buchpigel, Carlos A..; Braconi, Carla T.; Mendes, Erica; Sall, Amadou A.; Zanotto, Paolo M. de A.; Peron, Jean Pierre S.; Muotri, Alysson R.; Beltrão-Braga, Patricia C. B.

    2016-01-01

    Summary Zika virus (ZIKV) is an arbovirus belonging to the genus Flavivirus (Family Flaviviridae) and was first described in 1947 in Uganda following blood analyses of sentinel Rhesus monkeys1. Until the 20th century, the African and Asian lineages of the virus did not cause meaningful infections in humans. However, in 2007, vectored by Aedes aegypti mosquitoes, ZIKV caused the first noteworthy epidemic on the island of Yap in Micronesia2. Patients experienced fever, skin rash, arthralgia and conjunctivitis2. From 2013 to 2015, the Asian lineage of the virus caused further massive outbreaks in New Caledonia and French Polynesia. In 2013, ZIKV reached Brazil, later spreading to other countries in South and Central America3. In Brazil, the virus has been linked to congenital malformations, including microcephaly and other severe neurological diseases, such as Guillain-Barré syndrome4,5. Despite clinical evidence, direct experimental proof showing that the Brazilian ZIKV (ZIKVBR) strain causes birth defects remains missing6. Here we demonstrate that the ZIKVBR infects fetuses, causing intra-uterine growth restriction (IUGR), including signs of microcephaly in mice. Moreover, the virus infects human cortical progenitor cells, leading to an increase in cell death. Finally, we observed that the infection of human brain organoids resulted in a reduction of proliferative zones and disrupted cortical layers. These results indicate that ZIKVBR crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death by apoptosis and autophagy, impairing neurodevelopment. Our data reinforce the growing body of evidence linking the ZIKVBR outbreak to the alarming number of cases of congenital brain malformations. Our model can be used to determine the efficiency of therapeutic approaches to counteracting the harmful impact of ZIKVBR in human neurodevelopment. PMID:27279226

  7. The Brazilian Zika virus strain causes birth defects in experimental models.

    PubMed

    Cugola, Fernanda R; Fernandes, Isabella R; Russo, Fabiele B; Freitas, Beatriz C; Dias, João L M; Guimarães, Katia P; Benazzato, Cecília; Almeida, Nathalia; Pignatari, Graciela C; Romero, Sarah; Polonio, Carolina M; Cunha, Isabela; Freitas, Carla L; Brandão, Wesley N; Rossato, Cristiano; Andrade, David G; Faria, Daniele de P; Garcez, Alexandre T; Buchpigel, Carlos A; Braconi, Carla T; Mendes, Erica; Sall, Amadou A; Zanotto, Paolo M de A; Peron, Jean Pierre S; Muotri, Alysson R; Beltrão-Braga, Patricia C B

    2016-06-09

    Zika virus (ZIKV) is an arbovirus belonging to the genus Flavivirus (family Flaviviridae) and was first described in 1947 in Uganda following blood analyses of sentinel Rhesus monkeys. Until the twentieth century, the African and Asian lineages of the virus did not cause meaningful infections in humans. However, in 2007, vectored by Aedes aegypti mosquitoes, ZIKV caused the first noteworthy epidemic on the Yap Island in Micronesia. Patients experienced fever, skin rash, arthralgia and conjunctivitis. From 2013 to 2015, the Asian lineage of the virus caused further massive outbreaks in New Caledonia and French Polynesia. In 2013, ZIKV reached Brazil, later spreading to other countries in South and Central America. In Brazil, the virus has been linked to congenital malformations, including microcephaly and other severe neurological diseases, such as Guillain-Barré syndrome. Despite clinical evidence, direct experimental proof showing that the Brazilian ZIKV (ZIKV(BR)) strain causes birth defects remains absent. Here we demonstrate that ZIKV(BR) infects fetuses, causing intrauterine growth restriction, including signs of microcephaly, in mice. Moreover, the virus infects human cortical progenitor cells, leading to an increase in cell death. We also report that the infection of human brain organoids results in a reduction of proliferative zones and disrupted cortical layers. These results indicate that ZIKV(BR) crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death by apoptosis and autophagy, and impairing neurodevelopment. Our data reinforce the growing body of evidence linking the ZIKV(BR) outbreak to the alarming number of cases of congenital brain malformations. Our model can be used to determine the efficiency of therapeutic approaches to counteracting the harmful impact of ZIKV(BR) in human neurodevelopment.

  8. Effect of experimental exposure to differently virulent Aphanomyces astaci strains on the immune response of the noble crayfish Astacus astacus.

    PubMed

    Becking, Thomas; Mrugała, Agata; Delaunay, Carine; Svoboda, Jiří; Raimond, Maryline; Viljamaa-Dirks, Satu; Petrusek, Adam; Grandjean, Frédéric; Braquart-Varnier, Christine

    2015-11-01

    European crayfish are sensitive to the crayfish plague pathogen, Aphanomyces astaci, carried by North American crayfish species due to their less effective immune defence mechanisms against this disease. During a controlled infection experiment with a susceptible crayfish species Astacus astacus using three A. astaci strains (representing genotype groups A, B, and E), we investigated variation in their virulence and in crayfish immune defence indicators (haemocyte density, phenoloxidase activity, and production of reactive oxygen species). Experimental crayfish were exposed to two dosages of A. astaci spores (1 and 10 spores mL(-1)). The intensity and timing of the immune response differed between the strains as well as between the spore concentrations. Stronger and faster change in each immune parameter was observed in crayfish infected with two more virulent strains, indicating a relationship between crayfish immune response and A. astaci virulence. Similarly, the immune response was stronger and was observed earlier for the higher spore concentration. For the first time, the virulence of a strain of the genotype group E (isolated from Orconectes limosus) was experimentally tested. Total mortality was reached after 10 days for the two higher spore dosages (10 and 100 spores mL(-1)), and after 16 days for the lowest (1 spore mL(-1)), revealing equally high and rapid mortality as caused by the genotype group B (from Pacifastacus leniusculus). No mortality occurred after infection with genotype group A during 60 days of the experimental trial.

  9. Evaluation of capsular and acapsular strains of S. aureus in an experimental brain abscess model

    PubMed Central

    Esen, Nilufer; Wagoner, Gail; Philips, Napoleon

    2011-01-01

    Brain abscesses are mainly caused by either direct or indirect inoculation of gram positive bacteria including Stapylococcus aureus (S. aureus) or Streptococcus species into the central nervous system. In the present study, we aimed to compare potential changes in brain abscess pathogenesis induced by two different strains of S. aureus, namely the laboratory strain RN6390 and the clinical isolate Reynolds. Although the Reynolds strain was expected to be more resistant to eradication by the host, due to the existence of a polysaccharide capsule, and subsequently to be more virulent, instead we found parenchymal damage and mortality rates to be more prominent following RN6390 infection. In contrast, the Reynolds strain proliferated faster and induced early expression of the chemokine CXCL2, matrix metalloproteinase-9 (MMP-9), and complement 3a and C5. Furthermore, there were early and more abundant infiltration of PMNs, T cells and erythrocyte extravasation in brain abscesses induced by the Reynolds strain. However, several immune parameters were not different between the two strains during the later stages of the disease. These results suggest that capsular S. aureus can modulate innate immunity and complement system activation differently than the acapsular strain RN6390, and the early changes induced by Reynolds strain may have an important impact on survival. PMID:19906446

  10. Experimental infection of gnotobiotic piglets with Escherichia coli strains positive for EAST1 and AIDA.

    PubMed

    Zajacova, Zuzana Sramkova; Faldyna, Martin; Kulich, Pavel; Kummer, Vladimir; Maskova, Jarmila; Alexa, Pavel

    2013-03-15

    The virulence factors EAST1 and AIDA are often detected in ETEC/VTEC strains isolated from pigs and their role in diarrhoeal infections is discussed. In order to elucidate the pathogenesis of AIDA, the colonisation patterns of F4 positive and AIDA positive strains were investigated. Two wild-type Escherichia coli strains AIDA/EAST1 and F4/EAST1 isolated from diarrhoeal piglets were used for animal experiment to evaluate the ability of the EAST1 toxin to be involved in induction of diarrhoea. Gnotobiotic piglets were supplemented with normal porcine serum and orally inoculated with the strains. Faecal bacterial shedding of the challenge strains was observed during the experiment. Light microscopy and scanning electron microscopy were used to detect the colonisation pattern of both challenge strains. Although bacterial isolation demonstrated shedding of the challenge strains until the end of the experiment, diarrhoea did not develop in any piglet. Based on histological examination, piglets were more heavily colonised in the case of infection with E. coli O149/F4/EAST1 strain. Scanning electron microscopy showed bacterial cells of F4/EAST1 E. coli adhering to enterocytes, in contrast to AIDA/EAST1 which were poorly present on the intestinal surface. The EAST1 toxin alone was not able to induce diarrhoea in animals. Therefore our results demonstrate that the function/role of EAST1 and AIDA in colibacillosis of pigs remains to be elucidated.

  11. Experimental strain modal analysis for beam-like structure by using distributed fiber optics and its damage detection

    NASA Astrophysics Data System (ADS)

    Cheng, Liangliang; Busca, Giorgio; Cigada, Alfredo

    2017-07-01

    Modal analysis is commonly considered as an effective tool to obtain the intrinsic characteristics of structures including natural frequencies, modal damping ratios, and mode shapes, which are significant indicators for monitoring the health status of engineering structures. The complex mode indicator function (CMIF) can be regarded as an effective numerical tool to perform modal analysis. In this paper, experimental strain modal analysis based on the CMIF has been introduced. Moreover, a distributed fiber-optic sensor, as a dense measuring device, has been applied to acquire strain data along a beam surface. Thanks to the dense spatial resolution of the distributed fiber optics, more detailed mode shapes could be obtained. In order to test the effectiveness of the method, a mass lump—considered as a linear damage component—has been attached to the surface of the beam, and damage detection based on strain mode shape has been carried out. The results manifest that strain modal parameters can be estimated effectively by utilizing the CMIF based on the corresponding simulations and experiments. Furthermore, damage detection based on strain mode shapes benefits from the accuracy of strain mode shape recognition and the excellent performance of the distributed fiber optics.

  12. Fly's proprioception-inspired micromachined strain-sensing structure: idea, design, modeling and simulation, and comparison with experimental results

    NASA Astrophysics Data System (ADS)

    Wicaksono, D. H. B.; Zhang, L.-J.; Pandraud, G.; French, P. J.; Vincent, J. F. V.

    2006-04-01

    A new strain-sensing structure inspired from insect's (especially the Fly) propricoception sensor is devised. The campaniform sensillum is a strain-sensing microstructure with very high sensitivity despite its small dimension (diameter ~10 µm in a relatively stiff material of insect's exocuticle (E = ~109 Pa). Previous work shows that the high sensitivity of this structure towards strain is due to its membrane-in-recess- and strainconcentrating- hole- features. Based on this inspiration, we built similar structure using silicon micromachining technology. Then a simple characterisation setup was devised. Here, we present briefly, finite-element modeling and simulation based on this actual sample preparation for the characterisation. As comparison and also to understand mechanical features responsible for the strain-sensitivity, we performed the modeling on different mechanical structures: bulk chunk, blind-hole, thorugh-hole, surface membrane, and membrane-in-recess. The actual experimental characterisation was performed previously using optical technique to membranein- recess micromachined Si structure. The FEM simulation results confirm that the bending stress and strain are concentrated in the hole-vicinity. The membrane inside the hole acts as displacement transducer. The FEM is in conformity with previous analytical results, as well as the optical characterisation result. The end goal is to build a new type MEMS strain sensor.

  13. 3D Arrangement of Slip Systems in Non-Plane Strain: Experimental Plastic Deformation of Fine-Grained Limestone

    NASA Astrophysics Data System (ADS)

    Llana-Funez, S.; Rutter, E. H.

    2006-12-01

    The condition of simultaneous operation of five slip systems to produce homogeneous deformation by intracrystalline plasticity in polycrystalline aggregates is frequently simplified when applied to studying deformation in nature by considering other deformation mechanisms that relax the strict geometric condition. Insufficient knowledge of how these complementary mechanisms interact and accommodate geometrically non-plane strain situations obscure somehow subsequent interpretation of slip patterns in relation to principal strain axes. We ran an experimental program isolating intracrystalline plasticity from other deformation mechanisms with the aim of testing the effect of non-plane strain geometries in the 3D arrangement of crystallographic elements from which we inferred the orientation of active slip systems. We use a fine grained polycrystalline aggregate (Solnhofen Limestone), naturally doped at grain boundaries with organic matter preventing grain growth, that deforms plastically at the experimental conditions used (600 °C, 200 MPa confining pressure and 10^{- 4}s-1 strain rates). To maximize the number of strain geometries we used different experimental configurations (axi-symmetric shortening and extension, and direct shear) and also study in detail volumes where deformation is heterogeneous but still relatively simple. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. We were also able to obtain strain geometries where the vorticity axis in a non-coaxial deformation was either perpendicular to the extension direction (as in simple and sub-simple shear) or parallel to it. We measured the crystallographic preferred orientation (CPO) of calcite in deformed specimens by electron back-scattered diffraction techniques (EBSD), which allowed us to scan relatively small areas within already small specimens

  14. Experimental modal analysis and dynamic strain fiber Bragg gratings for structural health monitoring of composite antenna sub-reflector

    NASA Astrophysics Data System (ADS)

    Panopoulou, A.; Fransen, S.; Gomez-Molinero, V.; Kostopoulos, V.

    2013-09-01

    The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fiber Bragg grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behavior has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces an eigenfrequency shifting to lower values in the same sense as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. The correlation between the simulated damage and the loss of stiffness was analytically defined. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub-reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able

  15. Experimental Modal Analysis and Dynaic Strain Fiber Bragg Gratings for Structural Health Monitoring of Composite Aerospace Structures

    NASA Astrophysics Data System (ADS)

    Panopoulou, A.; Fransen, S.; Gomez Molinero, V.; Kostopoulos, V.

    2012-07-01

    The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces the same result as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub- reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation of both structures was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able via the FBG responses to identify a potential failure.

  16. Experimental Infection of Horses with an Attenuated Venezuelan Equine Encephalomyelitis Vaccine (Strain TC-83)

    PubMed Central

    Walton, Thomas E.; Alvarez, Otto; Buckwalter, Ross M.; Johnson, Karl M.

    1972-01-01

    Ten horses (Equus caballus) were vaccinated with strain TC-83 Venezuelan equine encephalomyelitis (VEE) virus vaccine. Febrile responses and leukopenia due to a reduction of lymphocytes and neutrophils were observed in all animals. Viremias were demonstrable in eight horses, with a maximum of 103.5 median tissue culture infectious dose units per ml of serum in two horses. Clinical illness with depression and anorexia were observed in five horses. Neutralizing (N), hemagglutination-inhibiting, and complement-fixing antibodies to the vaccine virus were demonstrable by 5, 6.5, and 7 days, respectively, after vaccination. Differential titrations of serum to six VEE strains revealed high titers of N antibody to vaccine virus, moderate titers to the epizootic Trinidad donkey no. 1 strain (VEE antigenic subtype I, variant A) from which TC-83 was derived, and low titers to two other epizootic strains (subtype I, variants B and C) in all horses at 1 month after vaccination; some animals responded with low levels of N antibody to the enzootic viruses (subtype I, variants D and E). Fourteen months after vaccination, six animals with detectable N antibody were challenged with MF-8 (subtype I, variant B), an epidemic-epizootic strain isolated in 1969 from a man in Honduras. All horses resisted challenge with the equine pathogenic strain of VEE. Marked increases of N antibody in most horses were demonstrable to some VEE strains when tested 1 month after challenge. PMID:4637604

  17. Assessment of attenuated Salmonella vaccine strains in controlling experimental Salmonella Typhimurium infection in chickens.

    PubMed

    Pei, Yanlong; Parreira, Valeria R; Roland, Kenneth L; Curtiss, Roy; Prescott, John F

    2014-01-01

    Salmonella hold considerable promise as vaccine delivery vectors for heterologous antigens in chickens. Such vaccines have the potential additional benefit of also controlling Salmonella infection in immunized birds. As a way of selecting attenuated strains with optimal immunogenic potential as antigen delivery vectors, this study screened 20 novel Salmonella Typhimurium vaccine strains, differing in mutations associated with delayed antigen synthesis and delayed attenuation, for their efficacy in controlling colonization by virulent Salmonella Typhimurium, as well as for their persistence in the intestine and the spleen. Marked differences were observed between strains in these characteristics, which provide the basis for selection for further study as vaccine vectors.

  18. Experimental Study of Solder/Copper Interface Failure Under Varying Strain Rates

    DTIC Science & Technology

    2011-03-01

    subjected to dynamic axial loads at strain rates between 10.0 s-1 and 0.05 s-1. The copper is alloy 101 and the lead-free solder has a composition of 96...OF SOLDER/COPPER INTERFACE FAILURE UNDER VARYING STRAIN RATES by Andrew Michael Luteran March 2011 Thesis Advisor: Young W. Kwon Second...tin and 4% silver. The tests results revealed that as the strain rate increases so do the ultimate and yield strengths but the elastic modulus

  19. Metal-backed versus all-polyethylene unicompartmental knee arthroplasty: Proximal tibial strain in an experimentally validated finite element model.

    PubMed

    Scott, C E H; Eaton, M J; Nutton, R W; Wade, F A; Evans, S L; Pankaj, P

    2017-01-01

    Up to 40% of unicompartmental knee arthroplasty (UKA) revisions are performed for unexplained pain which may be caused by elevated proximal tibial bone strain. This study investigates the effect of tibial component metal backing and polyethylene thickness on bone strain in a cemented fixed-bearing medial UKA using a finite element model (FEM) validated experimentally by digital image correlation (DIC) and acoustic emission (AE). A total of ten composite tibias implanted with all-polyethylene (AP) and metal-backed (MB) tibial components were loaded to 2500 N. Cortical strain was measured using DIC and cancellous microdamage using AE. FEMs were created and validated and polyethylene thickness varied from 6 mm to 10 mm. The volume of cancellous bone exposed to < -3000 µε (pathological loading) and < -7000 µε (yield point) minimum principal (compressive) microstrain and > 3000 µε and > 7000 µε maximum principal (tensile) microstrain was computed. Experimental AE data and the FEM volume of cancellous bone with compressive strain < -3000 µε correlated strongly: R = 0.947, R(2) = 0.847, percentage error 12.5% (p < 0.001). DIC and FEM data correlated: R = 0.838, R(2) = 0.702, percentage error 4.5% (p < 0.001). FEM strain patterns included MB lateral edge concentrations; AP concentrations at keel, peg and at the region of load application. Cancellous strains were higher in AP implants at all loads: 2.2- (10 mm) to 3.2-times (6 mm) the volume of cancellous bone compressively strained < -7000 µε. AP tibial components display greater volumes of pathologically overstrained cancellous bone than MB implants of the same geometry. Increasing AP thickness does not overcome these pathological forces and comes at the cost of greater bone resection.Cite this article: C. E. H. Scott, M. J. Eaton, R. W. Nutton, F. A. Wade, S. L. Evans, P. Pankaj. Metal-backed versus all-polyethylene unicompartmental knee arthroplasty: Proximal tibial strain in an experimentally validated

  20. Experimental model of infection with non-toxigenic strains of Corynebacterium diphtheriae and development of septic arthritis.

    PubMed

    Puliti, Manuela; von Hunolstein, Christina; Marangi, Maurizio; Bistoni, Francesco; Tissi, Luciana

    2006-02-01

    Corynebacterium diphtheriae is a well-known cause of localized respiratory tract infections. However, this micro-organism can also be associated with invasive infections, such as endocarditis, septic arthritis and osteomyelitis. Invasive infections are often caused by non-toxigenic strains. To set up an in vivo experimental model of C. diphtheriae infection, mice were infected intravenously with different doses (ranging from 1 x 10(7) to 5 x 10(8) bacteria per mouse) of three non-toxigenic strains, namely ISS-4749, ISS-4746 and ISS-3319. Similar mortality rates were observed with the three strains, with an LD50 ranging from 9 x 10(7) to 1.2 x 10(8). All strains were arthritogenic, although to different extents. ISS-4749 and ISS-4746 infection resulted in a maximum of 60 and 50 %, respectively, of animals with articular lesions, while in the ISS-3319-infected group only 25 % were positive. There were differences in systemic and joint cytokine production in the three experimental groups. ISS-4749- and ISS-4746-infected mice exhibited higher local levels of interleukin (IL)-6 and IL-1beta than ISS-3319-infected animals. At systemic levels, ISS-3319 was able to induce early and sustained production of interferon-gamma (IFN-gamma), but not IL-6. Conversely, infection with the other strains resulted in high IL-6, but not IFN-gamma, production. In conclusion, an experimental model of C. diphtheriae infection was set up, with development of septic arthritis. This model could be useful in studies on the pathogenicity and characterization of virulence factors other than toxin production.

  1. Experimental studies the evolution of stress-strain state in structured rock specimens under uniaxial loading

    NASA Astrophysics Data System (ADS)

    Oparin, Viktor; Tsoy, Pavel; Usoltseva, Olga; Semenov, Vladimir

    2014-05-01

    The aim of this study was to analyze distribution and development of stress-stress state in structured rock specimens subject to uniaxial loading to failure. Specific attention was paid to possible oscillating motion of structural elements of the rock specimens under constraints (pre-set stresses at the boundaries of the specimens) and the kinetic energy fractals. The detailed studies into the micro-level stress-strain state distribution and propagation over acting faces of rock specimens subject to uniaxial loading until failure, using automated digital speckle photography analyzer ALMEC-tv, have shown that: • under uniaxial stiff loading of prismatic sandstone, marble and sylvinite specimens on the Instron-8802 servohydraulic testing machine at the mobile grip displacement rate 0.02-0.2 mm/min, at a certain level of stressing, low-frequency micro-deformation processes originate in the specimens due to slow (quasi-static) force; • the amplitude of that deformation-wave processes greatly depends on the micro-loading stage: — at the elastic deformation stage, under the specimen stress lower than half ultimate strength of the specimen, there are no oscillations of microstrains; —at the nonlinearly elastic deformation stage, under stress varied from 0.5 to 1 ultimate strength of the specimens, the amplitudes of microstrains grow, including the descending stage 3; the oscillation frequency f=0.5-4 Hz; —at the residual strength stage, the amplitudes of the microstrains drop abruptly (3-5 times) as against stages 2 and 3; • in the elements of the scanned specimen surface in the region with the incipient crack, the microstrain rate amplitudes are a few times higher than in the undamged surface region of the same specimen. Sometimes, deformation rate greatly grows with increase in the load. The authors have used the energy scanning function of the deformation-wave processes in processing experimental speckle-photography data on the surface of the test specimen

  2. Simulation and experimental characterization of polymer/carbon nanotubes composites for strain sensor applications

    NASA Astrophysics Data System (ADS)

    De Vivo, B.; Lamberti, P.; Spinelli, G.; Tucci, V.; Vertuccio, L.; Vittoria, V.

    2014-08-01

    In this paper, a numerical model is presented in order to analyze the electrical characteristics of polymer composites filled by carbon nanotubes (CNTs) subject to tensile stress and investigate the possible usage of such materials as innovative sensors for small values of strain. The simulated mechano-electrical response of the nanocomposite is obtained through a multi-step approach which, through different modeling stages, provides a simple and effective tool for material analysis and design. In particular, at first, the morphological structures of the composites are numerically simulated by adopting a previously presented model based on a Monte Carlo procedure in which uniform distributions of the CNTs, approximated as of solid cylinders and ensuring some physical constraints, are dispersed inside a cubic volume representing the polymer matrix. Second, a geometrical analysis allows to obtain the percolation paths detected in the simulated structures. Suitable electrical networks composed by resistors and capacitors associated to the complex charge transport and polarization mechanisms occurring in the percolation paths are then identified. Finally, the variations of these circuit parameters, which are differently affected by the mechanical stresses applied to the composites, are considered to analyze the electromechanical characteristics of the composites and hence their performances as stress sensors. The proposed approach is used to investigate the impact on the electro-mechanical response of some physical properties of the base materials, such as the type of carbon nanotube, the height of energy barrier of polymer resin, as well as characteristics of the composite, i.e., the volume fraction of the filler. The tunneling effect between neighboring nanotubes is found to play a dominant role in determining the composite sensitivity to mechanical stresses. The simulation results are also compared with the experimental data obtained by performing stress tests on

  3. Experimental investigation of the behaviour of tungsten and molybdenum alloys at high strain-rate and temperature

    NASA Astrophysics Data System (ADS)

    Scapin, Martina; Fichera, Claudio; Carra, Federico; Peroni, Lorenzo

    2015-09-01

    The introduction in recent years of new, extremely energetic particle accelerators such as the Large Hadron Collider (LHC) gives impulse to the development and testing of refractory metals and alloys based on molybdenum and tungsten to be used as structural materials. In this perspective, in this work the experimental results of a tests campaign on Inermet® IT180 and pure Molybdenum (sintered by two different producers) are presented. The investigation of the mechanical behaviour was performed in tension varying the strain-rates, the temperatures and both of them. Overall six orders of magnitude in strain-rate (between 10-3 and 103 s-1) were covered, starting from quasi-static up to high dynamic loading conditions. The high strain-rate tests were performed using a direct Hopkinson Bar setup. Both in quasi-static and high strain-rate conditions, the heating of the specimens was obtained with an induction coil system, controlled in feedback loop, based on measurements from thermocouples directly welded on the specimen. The temperature range varied between 25 and 1000°C. The experimental data were, finally, used to extract the parameters of the Zerilli-Armstrong model used to reproduce the mechanical behaviour of the investigated materials.

  4. Safety and Protective Effectiveness of Two Strains of Lactobacillus with Probiotic Features in an Experimental Model of Salmonellosis

    PubMed Central

    Steinberg, Raphael S.; Silva, Lilian C. S.; Souza, Tássia C.; Lima, Maurício T.; de Oliveira, Nayara L. G.; Vieira, Leda Q.; Arantes, Rosa M. E.; Miyoshi, Anderson; Nicoli, Jacques R.; Neumann, Elisabeth; Nunes, Álvaro C.

    2014-01-01

    Two strains of Lactobacillus, previously isolated from bovine faeces and tested in vitro for properties desired in probiotics, were evaluated for their in vivo effectiveness in protecting against experimental salmonellosis. L. salivarius L38 and L. acidophilus L36 previously demonstrated the ability to successfully colonize the gastrointestinal tract of germ-free mice and stimulate the immune system associated with the intestinal mucosa. L38- or L36-feeding showed no detrimental effect on the general health indicators and did not induce changes in normal architecture of liver and small intestine, indicating that the use of these strains is apparently safe. In control animals fed L38 strain, several cytokines had augmented mRNA levels that can be associated with a homeostatic state of intestinal mucosa, while L36 had less diverse regulation. IgA production and secretion in the intestinal lumen induced by infection was abrogated by pretreating with both lactobacilli. In addition, liver and small intestine histological scores and, translocation of Salmonella cells to liver and spleen, indicated that these strains did not confer protection against the infection. So, the IL-12:IL-18➔IFN-γ axis, essential for an effective immune response against Salmonella, was not favored with L38 or L36 strains. However, increased expression of IL-10 in different portions of the gastrointestinal tract of L38-fed animals is indicative of anti-inflammatory effect to be explored furthermore. PMID:25162711

  5. Safety and protective effectiveness of two strains of Lactobacillus with probiotic features in an experimental model of salmonellosis.

    PubMed

    Steinberg, Raphael S; Silva, Lilian C S; Souza, Tássia C; Lima, Maurício T; de Oliveira, Nayara L G; Vieira, Leda Q; Arantes, Rosa M E; Miyoshi, Anderson; Nicoli, Jacques R; Neumann, Elisabeth; Nunes, Alvaro C

    2014-08-26

    Two strains of Lactobacillus, previously isolated from bovine faeces and tested in vitro for properties desired in probiotics, were evaluated for their in vivo effectiveness in protecting against experimental salmonellosis. L. salivarius L38 and L. acidophilus L36 previously demonstrated the ability to successfully colonize the gastrointestinal tract of germ-free mice and stimulate the immune system associated with the intestinal mucosa. L38- or L36-feeding showed no detrimental effect on the general health indicators and did not induce changes in normal architecture of liver and small intestine, indicating that the use of these strains is apparently safe. In control animals fed L38 strain, several cytokines had augmented mRNA levels that can be associated with a homeostatic state of intestinal mucosa, while L36 had less diverse regulation. IgA production and secretion in the intestinal lumen induced by infection was abrogated by pretreating with both lactobacilli. In addition, liver and small intestine histological scores and, translocation of Salmonella cells to liver and spleen, indicated that these strains did not confer protection against the infection. So, the IL-12:IL-18àIFN-g axis, essential for an effective immune response against Salmonella, was not favored with L38 or L36 strains. However, increased expression of IL-10 in different portions of the gastrointestinal tract of L38-fed animals is indicative of anti-inflammatory effect to be explored furthermore.

  6. Experimental study of the efficacy of linezolid alone and in combinations against experimental meningitis due to Staphylococcus aureus strains with decreased susceptibility to beta-lactams and glycopeptides.

    PubMed

    Cabellos, Carmen; Garrigós, Carmen; Taberner, Ferran; Force, Enriqueta; Pachón-Ibañez, M Eugenia

    2014-09-01

    To evaluate in vitro and in vivo efficacies of linezolid, vancomycin, and the combination of linezolid and rifampicin against two Staphylococcus aureus strains with reduced susceptibility to beta-lactams and one of them also to glycopeptides. In vitro killing curves and a rabbit model: Meningitis was induced by intracisternal inoculation of 10(8) CFU/ml of each strain. Five hours later (0 h), rabbits were randomly assigned to control or to therapeutic groups. CSF bacterial counts, lactate and protein concentrations, and pharmacokinetic parameters were determined. In vivo: linezolid and its combination with rifampicin reduced bacterial concentrations at 24 h, median cfu/mL 4.85 vs 3.87 (p < 0.05) for linezolid and 5.02 vs 4.21 (p < 0.05) for linezolid + rifampicin, against the glycopeptide intermediate S. aureus (GISA) strain and improved inflammatory parameters. Despite the need for more experimental data, our results suggest that linezolid and its combinations could be considered as a potential alternative in difficult-to-treat CNS infections and especially in those due to GISA strains and deserve more studies. Copyright © 2014 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  7. A musculoskeletal model of the equine forelimb for determining surface stresses and strains in the humerus-part II. Experimental testing and model validation.

    PubMed

    Pollock, Sarah; Stover, Susan M; Hull, M L; Galuppo, Larry D

    2008-08-01

    The first objective of this study was to experimentally determine surface bone strain magnitudes and directions at the donor site for bone grafts, the site predisposed to stress fracture, the medial and cranial aspects of the transverse cross section corresponding to the stress fracture site, and the middle of the diaphysis of the humerus of a simplified in vitro laboratory preparation. The second objective was to determine whether computing strains solely in the direction of the longitudinal axis of the humerus in the mathematical model was inherently limited by comparing the strains measured along the longitudinal axis of the bone to the principal strain magnitudes and directions. The final objective was to determine whether the mathematical model formulated in Part I [Pollock et al., 2008, ASME J. Biomech. Eng., 130, p. 041006] is valid for determining the bone surface strains at the various locations on the humerus where experimentally measured longitudinal strains are comparable to principal strains. Triple rosette strain gauges were applied at four locations circumferentially on each of two cross sections of interest using a simplified in vitro laboratory preparation. The muscles included the biceps brachii muscle in addition to loaded shoulder muscles that were predicted active by the mathematical model. Strains from the middle grid of each rosette, aligned along the longitudinal axis of the humerus, were compared with calculated principal strain magnitudes and directions. The results indicated that calculating strains solely in the direction of the longitudinal axis is appropriate at six of eight locations. At the cranial and medial aspects of the middle of the diaphysis, the average minimum principal strain was not comparable to the average experimental longitudinal strain. Further analysis at the remaining six locations indicated that the mathematical model formulated in Part I predicts strains within +/-2 standard deviations of experimental strains at

  8. Relating Histopathology and Mechanical Strain in Experimental Contusion Spinal Cord Injury in a Rat Model

    PubMed Central

    Liu, Jie; Yung, Andrew; Cripton, Peter; Kozlowski, Piotr; Tetzlaff, Wolfram; Oxland, Thomas

    2016-01-01

    Abstract During traumatic spinal cord injury (SCI), the spinal cord is subject to external displacements that result in damage of neural tissues. These displacements produce complex internal deformations, or strains, of the spinal cord parenchyma. The aim of this study is to determine a relationship between these internal strains during SCI and primary damage to spinal cord gray matter (GM) in an in vivo rat contusion model. Using magnetic resonance imaging and novel image registration methods, we measured three-dimensional (3D) mechanical strain in in vivo rat cervical spinal cord (n = 12) during an imposed contusion injury. We then assessed expression of the neuronal transcription factor, neuronal nuclei (NeuN), in ventral horns of GM (at the epicenter of injury as well as at intervals cranially and caudally), immediately post-injury. We found that minimum principal strain was most strongly correlated with loss of NeuN stain across all animals (R2 = 0.19), but varied in strength between individual animals (R2 = 0.06–0.52). Craniocaudal distribution of anatomical damage was similar to measured strain distribution. A Monte Carlo simulation was used to assess strain field error, and minimum principal strain (which ranged from 8% to 36% in GM ventral horns) exhibited a standard deviation of 2.6% attributed to the simulated error. This study is the first to measure 3D deformation of the spinal cord and relate it to patterns of ensuing tissue damage in an in vivo model. It provides a platform on which to build future studies addressing the tolerance of spinal cord tissue to mechanical deformation. PMID:26729511

  9. Relating Histopathology and Mechanical Strain in Experimental Contusion Spinal Cord Injury in a Rat Model.

    PubMed

    Bhatnagar, Tim; Liu, Jie; Yung, Andrew; Cripton, Peter; Kozlowski, Piotr; Tetzlaff, Wolfram; Oxland, Thomas

    2016-09-15

    During traumatic spinal cord injury (SCI), the spinal cord is subject to external displacements that result in damage of neural tissues. These displacements produce complex internal deformations, or strains, of the spinal cord parenchyma. The aim of this study is to determine a relationship between these internal strains during SCI and primary damage to spinal cord gray matter (GM) in an in vivo rat contusion model. Using magnetic resonance imaging and novel image registration methods, we measured three-dimensional (3D) mechanical strain in in vivo rat cervical spinal cord (n = 12) during an imposed contusion injury. We then assessed expression of the neuronal transcription factor, neuronal nuclei (NeuN), in ventral horns of GM (at the epicenter of injury as well as at intervals cranially and caudally), immediately post-injury. We found that minimum principal strain was most strongly correlated with loss of NeuN stain across all animals (R(2) = 0.19), but varied in strength between individual animals (R(2) = 0.06-0.52). Craniocaudal distribution of anatomical damage was similar to measured strain distribution. A Monte Carlo simulation was used to assess strain field error, and minimum principal strain (which ranged from 8% to 36% in GM ventral horns) exhibited a standard deviation of 2.6% attributed to the simulated error. This study is the first to measure 3D deformation of the spinal cord and relate it to patterns of ensuing tissue damage in an in vivo model. It provides a platform on which to build future studies addressing the tolerance of spinal cord tissue to mechanical deformation.

  10. Pathogenic outcome following experimental infection of sheep with Chlamydia abortus variant strains LLG and POS.

    PubMed

    Livingstone, Morag; Wheelhouse, Nicholas; Ensor, Hannah; Rocchi, Mara; Maley, Stephen; Aitchison, Kevin; Wattegedera, Sean; Wilson, Kim; Sait, Michelle; Siarkou, Victoria; Vretou, Evangelia; Entrican, Gary; Dagleish, Mark; Longbottom, David

    2017-01-01

    This study investigated the pathogenesis of two variant strains (LLG and POS) of Chlamydia abortus, in comparison to a typical wild-type strain (S26/3) which is known to be responsible for late term abortion in small ruminants. Challenge with the three strains at mid-gestation resulted in similar pregnancy outcomes, with abortion occurring in approximately 50-60% of ewes with the mean gestational lengths also being similar. However, differences were observed in the severity of placental pathology, with infection appearing milder for strain LLG, which was reflected in the lower number of organisms shed in vaginal swabs post-partum and less gross pathology and organisms present in placental smears. Results for strain POS were somewhat different than LLG with a more focal restriction of infection observed. Post-abortion antibody responses revealed prominent differences in seropositivity to the major outer membrane protein (MOMP) present in elementary body (EB) preparations under denaturing conditions, most notably with anti-LLG and anti-POS convalescent sera where there was no or reduced detection of MOMP present in EBs derived from the three strains. These results and additional analysis of whole EB and chlamydial outer membrane complex preparations suggest that there are conformational differences in MOMP for the three strains. Overall, the results suggest that gross placental pathology and clinical outcome is not indicative of bacterial colonization and the severity of infection. The results also highlight potential conformational differences in MOMP epitopes that perhaps impact on disease diagnosis and the development of new vaccines.

  11. Characterization of Two Campylobacter jejuni Strains for Use in Volunteer Experimental-Infection Studies▿ †

    PubMed Central

    Poly, Frédéric; Read, Timothy D.; Chen, Yu-Han; Monteiro, Mario A.; Serichantalergs, Oralak; Pootong, Piyarat; Bodhidatta, Ladaporn; Mason, Carl J.; Rockabrand, David; Baqar, Shahida; Porter, Chad K.; Tribble, David; Darsley, Michael; Guerry, Patricia

    2008-01-01

    The development of vaccines against Campylobacter jejuni would be facilitated by the ability to perform phase II challenge studies. However, molecular mimicry of the lipooligosaccharide (LOS) of most C. jejuni strains with human gangliosides presents safety concerns about the development of Guillain-Barré syndrome. Clinical isolates of C. jejuni that appeared to lack genes for the synthesis of ganglioside mimics were identified by DNA probe analyses. Two clinical isolates from Southeast Asia (strains BH-01-0142 and CG8421) were determined to express the LOS type containing N-acetyl quinovosamine. No ganglioside structures were observed to be present in the LOSs of these strains, and pyrosequence analyses of the genomes of both strains confirmed the absence of genes involved in ganglioside mimicry. The capsule polysaccharide (CPS) of BH-01-0142 was determined to be composed of galactose (Gal), 6-deoxy-ido-heptose, and, in smaller amounts, d-glycero-d-ido-heptose, and the CPS of CG8421 was observed to contain Gal, 6-deoxy-altro-heptose, N-acetyl-glucosamine, and minor amounts of 6-deoxy-3-O-Me-altro-heptose. Both CPSs were shown to carry O-methyl-phosphoramidate. The two genomes contained strain-specific zones, some of which could be traced to a plasmid origin, and both contained a large chromosomal insertion related to the CJEI3 element of C. jejuni RM1221. The genomes of both strains shared a high degree of similarity to each other and, with the exception of the capsule locus of CG8421, to the type strain of the HS3 serotype, TGH9011. PMID:18809665

  12. Natural and experimental infection with an attaching and effacing strain of Escherichia coli in calves.

    PubMed Central

    Moxley, R A; Francis, D H

    1986-01-01

    Gnotobiotic calves were inoculated with an O5:K4:H-, urease-positive strain of Escherichia coli isolated from a 2-day-old calf with diarrhea. The calves developed elevated temperatures and passed loose mucoid feces, with or without blood. The E. coli strain was negative for heat-stable and heat-labile enterotoxins but produced high levels of Shiga-like toxin. Bacteria attached diffusely to the epithelium of the large intestine and multifocally to the epithelium of the ileum. The duodenum and jejunum were not affected. At the sites of bacterial attachment, microvilli were effaced, enterocytes were degenerate, and necrosis and exfoliation had occurred. These results confirm a previous report from England that calves may naturally contract infections similar to those caused by enteropathogenic E. coli strains pathogenic to humans or rabbits. This suggests that the calf bacterial strains, like some enteropathogenic E. coli strains, produce high levels of Shiga-like toxin and cause attachment and effacement lesions in the colonic epithelium of the infected host. Images PMID:3525410

  13. Experimental Infection of Calves by Two Genetically-Distinct Strains of Rift Valley Fever Virus

    PubMed Central

    Wilson, William C.; Davis, A. Sally; Gaudreault, Natasha N.; Faburay, Bonto; Trujillo, Jessie D.; Shivanna, Vinay; Sunwoo, Sun Young; Balogh, Aaron; Endalew, Abaineh; Ma, Wenjun; Drolet, Barbara S.; Ruder, Mark G.; Morozov, Igor; McVey, D. Scott; Richt, Juergen A.

    2016-01-01

    Recent outbreaks of Rift Valley fever in ruminant livestock, characterized by mass abortion and high mortality rates in neonates, have raised international interest in improving vaccine control strategies. Previously, we developed a reliable challenge model for sheep that improves the evaluation of existing and novel vaccines in sheep. This sheep model demonstrated differences in the pathogenesis of Rift Valley fever virus (RVFV) infection between two genetically-distinct wild-type strains of the virus, Saudi Arabia 2001 (SA01) and Kenya 2006 (Ken06). Here, we evaluated the pathogenicity of these two RVFV strains in mixed breed beef calves. There was a transient increase in rectal temperatures with both virus strains, but this clinical sign was less consistent than previously reported with sheep. Three of the five Ken06-infected animals had an early-onset viremia, one day post-infection (dpi), with viremia lasting at least three days. The same number of SA01-infected animals developed viremia at 2 dpi, but it only persisted through 3 dpi in one animal. The average virus titer for the SA01-infected calves was 1.6 logs less than for the Ken06-infected calves. Calves, inoculated with either strain, seroconverted by 5 dpi and showed time-dependent increases in their virus-neutralizing antibody titers. Consistent with the results obtained in the previous sheep study, elevated liver enzyme levels, more severe liver pathology and higher virus titers occurred with the Ken06 strain as compared to the SA01 strain. These results demonstrate the establishment of a virulent challenge model for vaccine evaluation in calves. PMID:27223298

  14. Experimental Infection of Calves by Two Genetically-Distinct Strains of Rift Valley Fever Virus.

    PubMed

    Wilson, William C; Davis, A Sally; Gaudreault, Natasha N; Faburay, Bonto; Trujillo, Jessie D; Shivanna, Vinay; Sunwoo, Sun Young; Balogh, Aaron; Endalew, Abaineh; Ma, Wenjun; Drolet, Barbara S; Ruder, Mark G; Morozov, Igor; McVey, D Scott; Richt, Juergen A

    2016-05-23

    Recent outbreaks of Rift Valley fever in ruminant livestock, characterized by mass abortion and high mortality rates in neonates, have raised international interest in improving vaccine control strategies. Previously, we developed a reliable challenge model for sheep that improves the evaluation of existing and novel vaccines in sheep. This sheep model demonstrated differences in the pathogenesis of Rift Valley fever virus (RVFV) infection between two genetically-distinct wild-type strains of the virus, Saudi Arabia 2001 (SA01) and Kenya 2006 (Ken06). Here, we evaluated the pathogenicity of these two RVFV strains in mixed breed beef calves. There was a transient increase in rectal temperatures with both virus strains, but this clinical sign was less consistent than previously reported with sheep. Three of the five Ken06-infected animals had an early-onset viremia, one day post-infection (dpi), with viremia lasting at least three days. The same number of SA01-infected animals developed viremia at 2 dpi, but it only persisted through 3 dpi in one animal. The average virus titer for the SA01-infected calves was 1.6 logs less than for the Ken06-infected calves. Calves, inoculated with either strain, seroconverted by 5 dpi and showed time-dependent increases in their virus-neutralizing antibody titers. Consistent with the results obtained in the previous sheep study, elevated liver enzyme levels, more severe liver pathology and higher virus titers occurred with the Ken06 strain as compared to the SA01 strain. These results demonstrate the establishment of a virulent challenge model for vaccine evaluation in calves.

  15. Experimental and computational exploration of ground and excited state properties of highly strained ruthenium terpyridine complexes.

    PubMed

    Vallett, Paul J; Damrauer, Niels H

    2013-08-01

    Dissociative electron transfer reactions are prevalent in one-electron reduced aryl halides; however, calculations applied to charge-transfer excited states of metal complexes suggest that this reaction would be strongly endergonic unless attention is paid to specific structural details. In this current study, we explore the effect of introducing intramolecular strain into a series of halogenated ruthenium(II) polypyridyls. Parent [Ru(tpy)2](2+) (1) (tpy = 2,2':6',2″-terpyridine) is compared with two complexes, [Ru(6,6″-Br2-tpy)(tpy)](2+) (2) and [Ru(6,6″-Br2-tpy)2](2+) (3) (6,6″-Br2-tpy = 6,6″-dibromo-tpy) that incorporate interligand van der Waals strain derived from the large halogen substituents. DFT calculations and the crystal structure of 3 show how this strain distorts the geometry of 3 as compared to 1. Time-dependent DFT calculations are used to explain the effect of this strain on electronic absorption spectra where, in particular, a transition observed in 3 is attenuated in 2 and absent in 1 and heralds interligand charge transfer mediated by the halogen substituent. Ultrafast transient absorption spectroscopy reveals coherent vibrational dynamics particularly in 3 but also in 2 that is interpreted as reflecting heavy-atom motion. Surprisingly, in spite of the additional strain, the excited-state lifetime of 3 is observed to be approximately a factor of 6 longer than 2. Constrained-DFT calculations show that while the excited behavior of 2 is similar to 1, the strain-induced geometric distortions in 3 cause a nesting of excited state triplet surfaces resulting in a longer excited state lifetime. This may afford the additional time needed to engage in photochemistry, and kinetic evidence is observed for the breaking of a C-Br bond in 3 and formation of a contact ion pair state.

  16. Experimental deformation of coarse-grained rock salt to high strain

    NASA Astrophysics Data System (ADS)

    Linckens, J.; Zulauf, G.; Hammer, J.

    2016-08-01

    The processes and deformation mechanisms (e.g., dislocation creep, pressure solution, grain boundary sliding, and recrystallization) of rock salt are still a matter of debate. In order to fill this gap, high strain constriction experiments at 345°C, atmospheric pressure and a strain rate of 10-7 s-1 have been conducted on natural halite cuboids (60 × 60 × 45 mm) from the Morsleben mine of Northern Germany. Most samples were almost single crystals and contain a small amount of smaller grains (10-26%). The grain boundaries are decorated with fluid inclusions. The experiments were stopped at different final strains (ɛy = z of 10, 20, 30, and 40%) corresponding to a maximum strain (ɛx) range of 20-170%. The halite is deformed by dislocation creep, and the size of developed subgrains corresponds to the applied stress. The combined Schmid factor and subgrain boundary analysis indicate that slip was largely accommodated by the {110} < 110 > slip systems, with possible minor contribution by slip on the {100} < 110 > slip systems. Some of the deformed samples show evidence of grain boundary migration. In addition, subgrains with small misorientations form that result in large cumulative misorientations within a single grain (>40°). However, no subgrain rotation recrystallization is observed (i.e., misorientation angles are <10°). All the experiments show strain hardening, suggesting that recrystallization by grain boundary migration was not extensive and did not reset the microstructure. The experiments show that high finite strain in coarse-grained relatively dry rock salt can be accommodated by dislocation creep, without extensive dynamic recrystallization.

  17. Experimental characterisation of macro fibre composites and monolithic piezoelectric transducers for strain energy harvesting

    NASA Astrophysics Data System (ADS)

    Pozzi, Michele; Canziani, Alfredo; Durazo-Cardenas, Isidro; Zhu, Meiling

    2012-04-01

    μCompact and lightweight energy harvesters are needed to power wireless sensor nodes (WSNs). WSNs can provide health monitoring of aircraft structures, improving safety and reducing costs by enabling predictive maintenance. A simple solution, which meets the requirements for lightness and compactness, is represented by piezoelectric generators fixed to the surface of the wing (i.e. the wing skin). Such piezoelectric patches can harvest the strain energy available when the wing is flexed, as occurs, for example, in the presence of gust loading. For this study, monolithic piezoelectric sheets and macro fibre composite (MFC) generators were fixed to plates made of two materials commonly used for aircraft wing skin: Al-2024 aluminium alloy and an epoxy-carbon fibre composite. The plates then underwent harmonically varying loading in a tensile testing machine. The power generation of the harvesters was measured at a selection of strain levels and excitation frequencies, across a range of electrical loads. The optimal electrical load, yielding maximum power extraction, was identified for each working condition. The generated power increases quadratically with the strain and linearly with the frequency. The optimal electrical load decreases with increasing frequency and is only marginally dependent on strain. Absolute values of generated power were highest with the MFC, reaching 12mW (330μW/cm2) under 1170μstrain peak-to-peak excitation at 10Hz with a 66kΩ load. Power generation densities of 600μW/cm2 were achieved under 940μstrain with the monolithic transducers at 10Hz. It is found that MFCs have a lower power density than monolithic transducers, but, being more resilient, could be a more reliable choice. The power generated and the voltage outputs are appropriate for the intended application.

  18. Characterization of mechanisms of quinolone resistance in Pseudomonas aeruginosa strains isolated in vitro and in vivo during experimental endocarditis.

    PubMed Central

    Chamberland, S; Bayer, A S; Schollaardt, T; Wong, S A; Bryan, L E

    1989-01-01

    Mechanisms of resistance to quinolones were characterized in Pseudomonas aeruginosa strains isolated after Tn5 insertional mutagenesis and in resistant strains that emerged during pefloxacin therapy of experimental aortic endocarditis. Quinolone resistance achieved in in vitro-selected mutants Qr-1 and Qr-2 was associated with cross-resistance to several groups of antimicrobial agents, including beta-lactams, tetracycline, and chloramphenicol. A significant reduction of norfloxacin uptake was also observed. After ether permeabilization of the cells, DNA synthesis of these two isolates was as susceptible to norfloxacin as DNA synthesis of the parent strain (PAO1). These results indicate that alteration of outer membrane permeability is the primary determinant of resistance in these isolates. This altered cell permeability was correlated with reduction of outer membrane protein G (25.5 kilodaltons) and loss of a 40-kilodalton outer membrane protein in strain Qr-1. Resistance to quinolones that emerged during experimental endocarditis therapy was associated with both modification of outer membrane permeability (decreased uptake of norfloxacin) and decreased susceptibility of DNA synthesis to norfloxacin. Resistance was limited to quinolones and chloramphenicol. For these strains, norfloxacin inhibitory doses (50%) for DNA synthesis were identical to the drug MICs, suggesting that despite the identification of a permeability change, perhaps due to changes of lipopolysaccharide, the alteration of the quinolone intracellular target(s) susceptibility constitutes the primary determinant of resistance. Also, two distinct levels of norfloxacin resistance of DNA synthesis were found in these isolates, indicating that at least two distinct alterations of the drug target(s) are possible in P. aeruginosa. Images PMID:2502066

  19. Experimental infection of chickens with an atypical Mycoplasma gallisepticum strain: comparison of diagnostic methods.

    PubMed

    Kempf, I; Gesbert, F; Guittet, M

    1997-01-01

    Fifteen chickens were inoculated with the atypical Mycoplasma gallisepticum (MG) K703 strain. On different dates post inoculation, tracheal swab samples were collected for mycoplasma culture and blood samples were analysed by slide agglutination test (SA) with commercial or homologous antigen and enzyme-linked immunosorbent assay (ELISA) with three different kits. Results showed that MG isolation rate was low on several sampling dates. The SA with commercial antigen did not yield positive results, although birds were positive when tested with homologous antigen. With commercial ELISA kits, the numbers of positive samples remained low. These results illustrate the difficulty of diagnosis of infections with such MG variant strains.

  20. Comparison of abortion and infection after experimental challenge of pregnant bison and cattle with Brucella abortus strain 2308.

    PubMed

    Olsen, S C; Johnson, C

    2011-12-01

    A comparative study was conducted using data from naive bison (n = 45) and cattle (n = 46) from 8 and 6 studies, respectively, in which a standardized Brucella abortus strain 2308 experimental challenge was administered during midgestation. The incidence of abortion, fetal infection, uterine or mammary infection, or infection in maternal tissues after experimental challenge was greater (P < 0.05) in bison than in cattle. In animals that did abort, the time between experimental challenge and abortion was shorter (P < 0.05) for bison than for cattle. Brucella colonization of four target tissues and serologic responses on the standard tube agglutination test at the time of abortion did not differ (P > 0.05) between cattle and bison. The results of our study suggest that naive bison and cattle have similarities and differences after experimental exposure to a virulent B. abortus strain. Although our data suggest that bison may be more susceptible to infection with Brucella, some pathogenic characteristics of brucellosis were similar between bison and cattle.

  1. Reproduction of mucohaemorrhagic diarrhea and colitis indistinguishable from swine dysentery following experimental inoculation with "Brachyspira hampsonii" strain 30446.

    PubMed

    Rubin, Joseph E; Costa, Matheus O; Hill, Janet E; Kittrell, Heather E; Fernando, Champika; Huang, Yanyun; O'Connor, Brendan; Harding, John C S

    2013-01-01

    Mucohaemorrhagic diarrhea caused by Brachyspira hyodysenteriae, swine dysentery, is a severe production limiting disease of swine. Recently, pigs in western Canada with clinical signs indistinguishable from swine dysentery were observed. Despite the presence of spirochetes on fecal smears, recognized Brachyspira spp. including B. hyodysenteriae could not be identified. A phylogenetically distinct Brachyspira, called "B. hampsonii" strain 30446, however was isolated. The purpose of this study was to experimentally reproduce mucohaemorrhagic colitis and characterize strain 30446 shedding following inoculation. Eighteen 13-week-old pigs were randomly assigned to inoculation (n = 12) or control (n = 6) groups in each of two trials. In trial 1, pigs were inoculated with a tissue homogenate collected from clinically affected field cases. In trial 2, pigs were inoculated with a pure broth culture of strain 30446. In both trials, mucohaemorrhagic diarrhea was significantly more common in inoculated pigs than controls, all of which remained healthy. In animals with mucohaemorrhagic diarrhea, significantly more spirochetes were observed on Gram stained fecal smears, and higher numbers of strain 30446 genome equivalents were detected by quantitative PCR (qPCR). Strain 30446 was cultured from colon and/or feces of all affected but no control animals at necropsy. "Brachyspira hampsonii" strain 30446 causes mucohaemorrhagic diarrhea in pigs following a 4-9 day incubation period. Fecal shedding was detectable by day 4 post inoculation, and rarely preceded the onset of mucoid or haemorrhagic diarrhea by more than 2 days. Culture and 30446-specific qPCR are reliable methods of detection of this organism in feces and tissues of diarrheic pigs. The emergence of a novel Brachyspira spp., such as "B. hampsonii", creates diagnostic challenges including higher risk of false negative diagnostic tests. We therefore recommend diagnostic laboratories routinely use Brachyspira culture

  2. Analytical and experimental studies on the strain rate effects in penetration of 10wt % ballistic gelatin

    NASA Astrophysics Data System (ADS)

    Liu, L.; Jia, Z.; Ma, X. L.; Fan, Y. R.

    2013-07-01

    This work concentrates on modeling the super-elastic behavior of 10wt% ballistic gelatin at 4°C and the mechanical responses at quasi-static and high-speed penetrations. Uniaxial compression and simple shearing experiments were carried out to determine the moduli in Mooney-Rivlin model describing the elastic behavior of gelatin at low strain rates. The failure mode is determined to be elastic fracture as the tensile stretch ratio exceeds a critical value. For high compression strain rates, the available results from the split Hopkinson pressure bar (SHPB) experiments for 10wt% gelatin were carefully examined and assessed. Linear relationship between the moduli and the strain rate is established. Based on these material parameters, an analytic solution of stress for the quasi-static and quasi-dynamic expansion of spherical cavity in gelatin is derived. As a consequence, the work needed to open unit volume of cavity, Ps, which is the key parameter in studying penetration problems, is linearly increasing with the characteristic strain rate. The application of Ps to our quasi-static and high-speed penetration experiments is discussed and assessed.

  3. Lactobacillus casei strains isolated from cheese reduce biogenic amine accumulation in an experimental model.

    PubMed

    Herrero-Fresno, Ana; Martínez, Noelia; Sánchez-Llana, Esther; Díaz, María; Fernández, María; Martin, Maria Cruz; Ladero, Victor; Alvarez, Miguel A

    2012-07-02

    Tyramine and histamine are the biogenic amines (BAs) most commonly found in cheese, in which they appear as a result of the microbial enzymatic decarboxylation of tyrosine and histidine respectively. Given their toxic effects, their presence in high concentrations in foods should be avoided. In this work, samples of three cheeses (Zamorano, Cabrales and Emmental) with long ripening periods, and that often have high BA concentrations, were screened for the presence of BA-degrading lactic acid bacteria (LAB). Seventeen isolates were found that were able to degrade tyramine and histamine in broth culture. All 17 isolates were identified by 16S rRNA sequencing as belonging to Lactobacillus casei. They were typed by plasmid S1-PFGE and genomic macrorestriction-PFGE analysis. Two strains (L. casei 4a and 5b) associated with high degradation rates for both BAs were selected to test how this ability might affect histamine and tyramine accumulation in a Cabrales-like mini-cheese manufacturing model. The quantification of BAs and the monitoring of the strains' growth over ripening were undertaken by RP-HPLC and qPCR respectively. Both strains were found to reduce histamine and tyramine accumulation. These two strains might be suitable for use as adjunct cultures for reducing the presence of BAs in cheese. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Experimental studies with homologous subtype vaccines produced with multiple antigenically different seed strains

    USDA-ARS?s Scientific Manuscript database

    Due to the high antigenic variability of avian influenza virus, vaccines need to be continually updated to maintain adequate protection to evolving field strains. One possible approach, to mitigating the effects of antigenic change, is to use vaccines containing more than one isolate of the same su...

  5. ORGANIZATION TYPES AND ROLE STRAINS--AN EXPERIMENTAL STUDY OF COMPLEX ORGANIZATIONS.

    ERIC Educational Resources Information Center

    PALOLI, ERNEST G.

    AN INVESTIGATION WAS MADE ON THE RELATIONSHIP BETWEEN CONTRASTING ORGANIZATIONAL TYPES CREATED IN THE LABORATORY SETTING AND THE DISTRIBUTION OF THREE TYPES OF ROLE STRAINS--ROLE UNCERTAINTY, ROLE DISPARITY, AND ROLE INCOMPATIBILITY. THE TWO ORGANIZATION TYPES STUDIED DIFFERED IN DEGREE OF SPECIALIZATION, EMPHASIS ON RULES AND REGULATIONS, AMOUNT…

  6. Experimental Infection of Calves with Escherichia coli O104:H4 outbreak strain

    PubMed Central

    Hamm, K.; Barth, S. A.; Stalb, S.; Geue, L.; Liebler-Tenorio, E.; Teifke, J. P.; Lange, E.; Tauscher, K.; Kotterba, G.; Bielaszewska, M.; Karch, H.; Menge, C.

    2016-01-01

    In 2011, a severe outbreak of hemolytic-uremic syndrome was caused by an unusual, highly virulent enterohemorrhagic E. coli (EHEC) O104:H4 strain, which possessed EHEC virulence traits in the genetic background of human-adapted enteroaggregative E. coli. To determine magnitude of fecal shedding and site of colonization of EHEC O104:H4 in a livestock host, 30 (ten/strain) weaned calves were inoculated with 1010 CFU of EHEC O104:H4, EHEC O157:H7 (positive control) or E. coli strain 123 (negative control) and necropsied (4 or 28 d.p.i.). E. coli O157:H7 was recovered until 28 d.p.i. and O104:H4 until 24 d.p.i. At 4 d.p.i., EHEC O104:H4 was isolated from intestinal content and detected associated with the intestinal mucosa. These results are the first evidence that cattle, the most important EHEC reservoir, can also carry unusual EHEC strains at least transiently, questioning our current understanding of the molecular basis of host adaptation of this important E. coli pathovar. PMID:27600997

  7. Molecular characterization of Trypanosoma cruzi Mexican strains and their behavior in the mouse experimental model.

    PubMed

    Gómez-Hernández, César; Rezende-Oliveira, Karine; Nascentes, Gabriel Antônio Nogueira; Batista, Lara Rocha; Kappel, Henrique Borges; Martinez-Ibarra, José Alejandro; Trujillo Contreras, Francisco; Lages-Silva, Eliane; Ramírez, Luis Eduardo

    2011-01-01

    For a long time, the importance of Chagas disease in Mexico, where many regarded it as an exotic malady, was questioned. Considering the great genetic diversity among isolates of Trypanosoma cruzi, the importance of this biological characterization, and the paucity of information on the clinical and biological aspects of Chagas disease in Mexico, this study aimed to identify the molecular and biological characterization of Trypanosoma cruzi isolates from different endemic areas of this country, especially of the State of Jalisco. Eight Mexican Trypanosoma cruzi strains were biologically and genetically characterized (PCR specific for Trypanosoma cruzi, multiplex-PCR, amplification of space no transcript of the genes of the mini-exon, amplification of polymorphic regions of the mini-exon, classification by amplification of intergenic regions of the spliced leader genes, RAPD (random amplified polymorphic DNA). Two profiles of parasitaemia were observed, patent (peak parasitaemia of 4.6×10(6) to 10(7) parasites/mL) and subpatent. In addition, all isolates were able to infect 100% of the animals. The isolates mainly displayed tropism for striated (cardiac and skeletal) muscle. PCR amplification of the mini-exon gene classified the eight strains as TcI. The RAPD technique revealed intraspecies variation among isolates, distinguishing strains isolated from humans and triatomines and according to geographic origin. The Mexican T. cruzi strains are myotrophic and belong to group TcI.

  8. Experimental Infection of Richardson's Ground Squirrels (Spermophilus richardsonii) with Attenuated and Virulent Strains of Brucella abortus

    USDA-ARS?s Scientific Manuscript database

    Exposure of non-target species to wildlife vaccines is an important concern when evaluating a candidate vaccine for use in the field. A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various non-target species suggested that Richardson’s ground squirrels (Spermophil...

  9. Experimental Comparison of Tantalum Material Strength between Single Crystal [100] and [111] Samples at High Pressure and Strain Rates

    NASA Astrophysics Data System (ADS)

    Plechaty, Christopher; Park, Hye-Sook; Cavallo, Rob; Prisbrey, Shon; Rudd, Robert; Wehrenberg, Christopher; Huntington, Channing; Maddox, Brian; May, Mark; Remington, Bruce

    2013-10-01

    Experiments were performed using the OMEGA laser to investigate Ta material strength at high pressure (1 Mbar), and high strain rates (106-108 s-1) . To achieve these pressures and strain rates in experiment without melting the sample, a quasi-isentropic drive was employed to drive the growth of pre-imposed sinusoidal perturbations embedded on the surface of the Ta sample, via the Rayleigh-Taylor (RT) instability. By measuring the ripple amplitude using face-on high energy (~ 22 KeV) radiography, the strength of the Ta sample was inferred from the amount of RT growth observed. Under these experimental conditions, the Ta material strength can be modeled by the Multiscale (MS) model, developed at LLNL. In this study, we performed a side-by-side comparison of the ripple growth on [100] and [111] orientated single-crystal Ta samples for the same shot and drive conditions. The objective was to determine if a difference in the growth predicted by the MS model could be observed at the high pressure and strain rates present in our experiments, and within the error bars of the experimental technique. Prepared by LLNL under Contract DE-AC52-07NA27344.

  10. Experimental Techniques for Evaluating the Effects of Aging on Impact and High Strain Rate Properties of Triaxial Braided Composite Materials

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.; Ruggeri, Charles R.; Gilat, Amos; Matrka, Thomas

    2010-01-01

    An experimental program is underway to measure the impact and high strain rate properties of triaxial braided composite materials and to quantify any degradation in properties as a result of thermal and hygroscopic aging typically encountered during service. Impact tests are being conducted on flat panels using a projectile designed to induce high rate deformation similar to that experienced in a jet engine fan case during a fan blade-out event. The tests are being conducted on as-fabricated panels and panels subjected to various numbers of aging cycles. High strain rate properties are being measured using a unique Hopkinson bar apparatus that has a larger diameter than conventional Hopkinson bars. This larger diameter is needed to measure representative material properties because of the large unit cell size of the materials examined in this work. In this paper the experimental techniques used for impact and high strain rate testing are described and some preliminary results are presented for both as-fabricated and aged composites.

  11. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: Experimental design and preliminary results

    NASA Astrophysics Data System (ADS)

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  12. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

    PubMed

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed.

  13. Inbred Strains Derived from Feral Mice Reveal New Pathogenic Mechanisms of Experimental Leishmaniasis Due to Leishmania major

    PubMed Central

    Babay, Besma E. C.; Louzir, Hechmi; Kebaïer, Chahnaz; Boubaker, Samir; Dellagi, Koussay; Cazenave, Pierre-André

    2004-01-01

    Two inbred mouse strains, derived from feral founders, are susceptible to experimental leishmaniasis due to Leishmania major and support a disease of a severity intermediate between those observed in strains C57BL/6 and BALB/c. Mice of the MAI strain develop a severe, nonhealing, but nonfatal disease with no resistance to a secondary parasite challenge. The immunological responses showed a TH2 dominance characterized by an early peak of interleukin-4 (IL-4) and IL-13. However, neutralization of IL-4, which leads to a resistance phenotype in BALB/c mice, has no effect on disease progression in MAI mice. Mice of strain PWK develop a protracted but self-healing disease, characterized by a mixed TH1-plus-TH2 pattern of immune responses in which IL-10 plays an aggravating role, and acquire resistance to a secondary challenge. These features are close to those observed in human cutaneous leishmaniasis due to L. major and make PWK mice a suitable model for the human disease. PMID:15271920

  14. Inbred strains derived from feral mice reveal new pathogenic mechanisms of experimental leishmaniasis due to Leishmania major.

    PubMed

    Babay, Besma E C; Louzir, Hechmi; Kebaïer, Chahnaz; Boubaker, Samir; Dellagi, Koussay; Cazenave, Pierre-André

    2004-08-01

    Two inbred mouse strains, derived from feral founders, are susceptible to experimental leishmaniasis due to Leishmania major and support a disease of a severity intermediate between those observed in strains C57BL/6 and BALB/c. Mice of the MAI strain develop a severe, nonhealing, but nonfatal disease with no resistance to a secondary parasite challenge. The immunological responses showed a TH2 dominance characterized by an early peak of interleukin-4 (IL-4) and IL-13. However, neutralization of IL-4, which leads to a resistance phenotype in BALB/c mice, has no effect on disease progression in MAI mice. Mice of strain PWK develop a protracted but self-healing disease, characterized by a mixed TH1-plus-TH2 pattern of immune responses in which IL-10 plays an aggravating role, and acquire resistance to a secondary challenge. These features are close to those observed in human cutaneous leishmaniasis due to L. major and make PWK mice a suitable model for the human disease.

  15. Experimental characterization and modeling of UO2 grain boundary cracking at high temperatures and high strain rates

    NASA Astrophysics Data System (ADS)

    Salvo, Maxime; Sercombe, Jérôme; Helfer, Thomas; Sornay, Philippe; Désoyer, Thierry

    2015-05-01

    In this paper, the behavior of a dense UO2 (porosity less than 2%) was studied experimentally on a range of temperatures (1100-1700 °C) and strain rates (10-4-10-1 /s) representative of RIA loading conditions. The yield stress was found to increase with strain rate and to decrease with temperature. Macroscopic cracking of the samples was apparent after the tests at 1100 °C. Scanning Electron Microscopy (SEM) image analyses revealed a pronounced grain boundary cracking in the core of the samples tested at 10-1 /s and at 1550-1700 °C. A hyperbolic sine model for the viscoplastic strain rate with a clear dependency on porosity was first developed. It was completed by a Drucker-Prager yield criterion with associated plastic flow to account for the porosity increase induced by grain boundary cracking. Finite Elements simulations of the compression tests on the dense UO2 were then successfully compared to the stress-strain curves, post-test diameter profiles and porosities at the pellets' center, periphery and top extremity. The response of the grain boundary cracking model was then studied in biaxial compression, this condition being closer to that of the pellet during a RIA power transient.

  16. Rheology of Arc Dacite Lavas: Experimental Determination at Low Strain Rates

    NASA Astrophysics Data System (ADS)

    Avard, G.; Whittington, A. G.

    2010-12-01

    Andesitic-dacitic volcanoes exhibit a large variety of eruption styles, including explosive eruptions, endogenous and exogenous dome growth, and km-long lava flows. The rheology of these lavas can be investigated through field observations of flow and dome morphology, but this approach integrates the properties of lava over a wide range of temperatures. Another approach is through laboratory experiments, however previous studies have used higher shear stresses and strain rates than are appropriate to lava flows. We measured the apparent viscosity of several lavas from Santiaguito and Bezymianny by uniaxial compression, between 1153 and 1313 K, at low shear stress (0.085 to 0.42 MPa), low strain rate (between 1.1●10-8 and 1.9●10-5 s-1), and up to 43.7 % total deformation. The results show a strong variability of the apparent viscosity between different samples, which can be ascribed to differences in initial porosity and crystallinity. Our experiments yield apparent viscosities more than 1 order of magnitude lower than predicted by models based on experiments at higher strain rates. At lava flow conditions, no evidence of a yield strength is observed and the apparent viscosity is best approached by a strain rate- and temperature-dependent power law equation. The best fit for data from juvenile Santiaguito lava, for temperatures between ~890 and ~950○C, and strain rates lower than ~1.8●10-4 s-1, is log ηapp = -0.738+9.24●103/T(K)-0.654●log dɛ/dt, where ηapp is apparent viscosity and dɛ/dt is strain rate. This equation also reproduced 45 data for a juvenile sample from Bezymianny with a root mean square deviation of 0.19 log unit Pa.s. Applying the rheological model to lava flow conditions at Santiaguito yields calculated apparent viscosities that are in reasonable agreement with field observations, and suggests that internal shear heating may be significant ongoing heat source within these flows, enabling highly viscous lava to travel long distances.

  17. Rheology of arc dacite lavas: experimental determination at low strain rates

    NASA Astrophysics Data System (ADS)

    Avard, Geoffroy; Whittington, Alan G.

    2012-07-01

    Andesitic-dacitic volcanoes exhibit a large variety of eruption styles, including explosive eruptions, endogenous and exogenous dome growth, and kilometer-long lava flows. The rheology of these lavas can be investigated through field observations of flow and dome morphology, but this approach integrates the properties of lava over a wide range of temperatures. Another approach is through laboratory experiments; however, previous studies have used higher shear stresses and strain rates than are appropriate to lava flows. We measured the apparent viscosity of several lavas from Santiaguito and Bezymianny volcanoes by uniaxial compression, between 1,109 and 1,315 K, at low shear stress (0.085 to 0.42 MPa), low strain rate (between 1.1 × 10-8 and 1.9 × 10-5 s-1), and up to 43.7 % total deformation. The results show a strong variability of the apparent viscosity between different samples, which can be ascribed to differences in initial porosity and crystallinity. Deformation occurs primarily by compaction, with some cracking and/or vesicle coalescence. Our experiments yield apparent viscosities more than 1 order of magnitude lower than predicted by models based on experiments at higher strain rates. At lava flow conditions, no evidence of a yield strength is observed, and the apparent viscosity is best approached by a strain rate- and temperature-dependent power law equation. The best fit for Santiaguito lava, for temperatures between 1,164 and 1,226 K and strain rates lower than 1.8 × 10-4 s-1, is log {η_{{app}}} = - 0.738 + 9.24 × {10^3}{/}T(K) - 0.654 \\cdot log dot{\\varepsilon } where η app is apparent viscosity and dot{\\varepsilon } is strain rate. This equation also reproduced 45 data for a sample from Bezymianny with a root mean square deviation of 0.19 log unit Pa s. Applying the rheological model to lava flow conditions at Santiaguito yields calculated apparent viscosities that are in reasonable agreement with field observations and suggests that

  18. Quantitative detection of Toxoplasma gondii in tissues of experimentally infected turkeys and in retail turkey products by magnetic-capture PCR.

    PubMed

    Koethe, Martin; Straubinger, Reinhard K; Pott, Susan; Bangoura, Berit; Geuthner, Anne-Catrin; Daugschies, Arwid; Ludewig, Martina

    2015-12-01

    Magnetic-capture PCR was applied for the quantitative detection of Toxoplasma gondii in tissues of experimentally infected turkeys and retail turkey meat products. For experimental infection, three T. gondii strains (ME49, CZ-Tiger, NED), varying infectious doses in different matrices (organisms in single mouse brains or 10(3), 10(5), or 10(6) oocysts in buffer) were used. From all animals, breast, thigh, and drumstick muscle tissues and for CZ-Tiger-infected animals additionally brains and hearts were analyzed. Using the magnetic-capture PCR large volumes of up to 100 g were examined. Our results show that most T. gondii parasites are present in brain and heart tissue. Of the three skeletal muscle types, drumsticks were affected at the highest and breast at the lowest level. Type III strain (NED) seems to be less efficient in infecting turkeys compared to type II strains, because only few tissues of NED infected animals contained T. gondii DNA. Furthermore, the number of detected parasitic stages increased with the level of infectious dose. Infection mode by either oocyst or tissue cyst stage did not have an effect on the amount of T. gondii present in tissues. In retail turkey meat products T. gondii DNA was not detectable although a contact with the parasite was inferred by serology.

  19. Predictions and Experimental Microstructural Characterization of High Strain Rate Failure Modes in Layered Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Khanikar, Prasenjit

    Different aluminum alloys can be combined, as composites, for tailored dynamic applications. Most investigations pertaining to metallic alloy layered composites, however, have been based on quasi-static approaches. The dynamic failure of layered metallic composites, therefore, needs to be characterized in terms of strength, toughness, and fracture response. A dislocation-density based crystalline plasticity formulation, finite-element techniques, rational crystallographic orientation relations and a new fracture methodology were used to predict the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on an overlap method and phantom nodes, is used with a fracture criteria specialized for fracture on different cleavage planes. One of the objectives of this investigation, therefore, was to determine the optimal arrangements of the 2139 and 2195 aluminum alloys for a metallic layered composite that would combine strength, toughness and fracture resistance for high strain-rate applications. Different layer arrangements were investigated for high strain-rate applications, and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance. The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-boned interface and the potential delamination of the layers. Shear strain localization, dynamic cracking and delamination were the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be optimized for high strain

  20. Enhanced Reactivity in Dioxirane C-H Oxidations via Strain Release: A Computational and Experimental Study

    PubMed Central

    Zou, Lufeng; Paton, Robert S.; Eschenmoser, Albert; Newhouse, Timothy R.; Baran, Phil S.; Houk, K. N.

    2013-01-01

    The site- and stereo-selectivities of C-H oxidations of substituted cyclohexanes and trans-decalins by dimethyldioxirane (DMDO) were investigated computationally with quantum mechanical density functional theory (DFT). The multi-configuration CASPT2 method was employed on model systems to establish the preferred mechanism and transition state geometry. The reaction pathway involving a rebound step is established to account for the retention of stereochemistry. The oxidation of sclareolide with dioxirane reagents is reported, including the oxidation by the in situ generated tBu-TFDO, a new dioxirane that better discriminates between C-H bonds based on steric effects. The release of 1,3-diaxial strain in the transition state contributes to the site selectivity and enhanced axial reactivity for tertiary C-H bonds, a result of the lowering of distortion energy. In addition to this strain release factor, steric and inductive effects contribute to the rates of C-H oxidation by dioxiranes. PMID:23461537

  1. Determination and Finite Element Validation of the WYPIWYG Strain Energy of Superficial Fascia from Experimental Data.

    PubMed

    Latorre, Marcos; Peña, Estefanía; Montáns, Francisco J

    2017-03-01

    What-You-Prescribe-Is-What-You-Get (WYPIWYG) procedures are a novel and general phenomenological approach to modelling the behavior of soft materials, applicable to biological tissues in particular. For the hyperelastic case, these procedures solve numerically the nonlinear elastic material determination problem. In this paper we show that they can be applied to determine the stored energy density of superficial fascia. In contrast to the usual approach, in such determination no user-prescribed material parameters and no optimization algorithms are employed. The strain energy densities are computed solving the equilibrium equations of the set of experiments. For the case of superficial fascia it is shown that the mechanical behavior derived from such strain energies is capable of reproducing simultaneously the measured load-displacement curves of three experiments to a high accuracy.

  2. Time Domain Strain/Stress Reconstruction Based on Empirical Mode Decomposition: Numerical Study and Experimental Validation

    PubMed Central

    He, Jingjing; Zhou, Yibin; Guan, Xuefei; Zhang, Wei; Zhang, Weifang; Liu, Yongming

    2016-01-01

    Structural health monitoring has been studied by a number of researchers as well as various industries to keep up with the increasing demand for preventive maintenance routines. This work presents a novel method for reconstruct prompt, informed strain/stress responses at the hot spots of the structures based on strain measurements at remote locations. The structural responses measured from usage monitoring system at available locations are decomposed into modal responses using empirical mode decomposition. Transformation equations based on finite element modeling are derived to extrapolate the modal responses from the measured locations to critical locations where direct sensor measurements are not available. Then, two numerical examples (a two-span beam and a 19956-degree of freedom simplified airfoil) are used to demonstrate the overall reconstruction method. Finally, the present work investigates the effectiveness and accuracy of the method through a set of experiments conducted on an aluminium alloy cantilever beam commonly used in air vehicle and spacecraft. The experiments collect the vibration strain signals of the beam via optical fiber sensors. Reconstruction results are compared with theoretical solutions and a detailed error analysis is also provided. PMID:27537889

  3. Rapid multiple-level coevolution in experimental populations of yeast killer and nonkiller strains.

    PubMed

    Pieczynska, Magdalena D; Wloch-Salamon, Dominika; Korona, Ryszard; de Visser, J Arjan G M

    2016-06-01

    Coevolution between different biological entities is considered an important evolutionary mechanism at all levels of biological organization. Here, we provide evidence for coevolution of a yeast killer strain (K) carrying cytoplasmic dsRNA viruses coding for anti-competitor toxins and an isogenic toxin-sensitive strain (S) during 500 generations of laboratory propagation. Signatures of coevolution developed at two levels. One of them was coadaptation of K and S. Killing ability of K first increased quickly and was followed by the rapid invasion of toxin-resistant mutants derived from S, after which killing ability declined. High killing ability was shown to be advantageous when sensitive cells were present but costly when they were absent. Toxin resistance evolved via a two-step process, presumably involving the fitness-enhancing loss of one chromosome followed by selection of a recessive resistant mutation on the haploid chromosome. The other level of coevolution occurred between cell and killer virus. By swapping the killer viruses between ancestral and evolved strains, we could demonstrate that changes observed in both host and virus were beneficial only when combined, suggesting that they involved reciprocal changes. Together, our results show that the yeast killer system shows a remarkable potential for rapid multiple-level coevolution. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  4. Integrated experimental and computational studies of deformation of single crystal copper at high strain rates

    NASA Astrophysics Data System (ADS)

    Rawat, S.; Chandra, S.; Chavan, V. M.; Sharma, S.; Warrier, M.; Chaturvedi, S.; Patel, R. J.

    2014-12-01

    Quasi-static (0.0033 s-1) and dynamic (103 s-1) compression experiments were performed on single crystal copper along ⟨100⟩ and ⟨110⟩ directions and best-fit parameters for the Johnson-Cook (JC) material model, which is an important input to hydrodynamic simulations for shock induced fracture, have been obtained. The deformation of single crystal copper along the ⟨110⟩ direction showed high yield strength, more strain hardening, and less strain rate sensitivity as compared to the ⟨100⟩ direction. Although the JC model at the macro-scale is easy to apply and describes a general response of material deformation, it lacks physical mechanisms that describe the influence of texture and initial orientation on the material response. Hence, a crystal plasticity model based on the theory of thermally activated motion of dislocations was used at the meso-scale, in which the evolution equations permit one to study and quantify the influence of initial orientation on the material response. Hardening parameters of the crystal plasticity model show less strain rate sensitivity along the ⟨110⟩ orientation as compared to the ⟨100⟩ orientation, as also shown by the JC model. Since the deformation process is inherently multiscale in nature, the shape changes observed in the experiments due to loading along ⟨100⟩ and ⟨110⟩ directions are also validated by molecular dynamics simulations at the nano-scale.

  5. Time Domain Strain/Stress Reconstruction Based on Empirical Mode Decomposition: Numerical Study and Experimental Validation.

    PubMed

    He, Jingjing; Zhou, Yibin; Guan, Xuefei; Zhang, Wei; Zhang, Weifang; Liu, Yongming

    2016-08-16

    Structural health monitoring has been studied by a number of researchers as well as various industries to keep up with the increasing demand for preventive maintenance routines. This work presents a novel method for reconstruct prompt, informed strain/stress responses at the hot spots of the structures based on strain measurements at remote locations. The structural responses measured from usage monitoring system at available locations are decomposed into modal responses using empirical mode decomposition. Transformation equations based on finite element modeling are derived to extrapolate the modal responses from the measured locations to critical locations where direct sensor measurements are not available. Then, two numerical examples (a two-span beam and a 19956-degree of freedom simplified airfoil) are used to demonstrate the overall reconstruction method. Finally, the present work investigates the effectiveness and accuracy of the method through a set of experiments conducted on an aluminium alloy cantilever beam commonly used in air vehicle and spacecraft. The experiments collect the vibration strain signals of the beam via optical fiber sensors. Reconstruction results are compared with theoretical solutions and a detailed error analysis is also provided.

  6. The influence of strain localisation on the rotation behaviour of rigid objects in experimental shear zones

    NASA Astrophysics Data System (ADS)

    ten Grotenhuis, Saskia M.; Passchier, Cees W.; Bons, Paul D.

    2002-03-01

    Mica fish and tourmaline fish from natural mylonites were analysed in thin section to determine their orientation distribution. They are oriented with their long axes tilted with respect to the mylonitic foliation, and fish with a small aspect ratio exhibit a slightly larger angle than fish with a large aspect ratio. This orientation seems to be a stable orientation for the mica and tourmaline fish. Analogue experiments with two rheologically different matrix materials were performed to explain the data. One material was PDMS, a linear viscous polymer. The other was tapioca pearls, a granular material with low cohesion and Mohr-Coulomb type behaviour. In contrast to a fairly homogeneous strain distribution in PDMS, distinct small-scale shear bands developed in tapioca pearls during deformation. Experiments modelled different vorticity numbers and parallelogram-shaped rigid objects with different aspect ratios were used. Rotation rates of objects in a viscous matrix are very similar to analytical solutions for ellipses in viscous flow, but stable orientations differ from data of natural examples. In all experiments with a Mohr-Coulomb matrix elongated objects had a stable orientation due to small-scale strain localisation. We therefore suggest that small-scale strain localisation (≤mm) that might be hidden by ongoing deformation and recrystallisation processes, is an important characteristic of the rheology of mylonites.

  7. Experimental mouse lethality of Escherichia coli strains isolated from free ranging Tibetan yaks.

    PubMed

    Rehman, Mujeeb Ur; Zhang, Hui; Wang, Yajing; Mehmood, Khalid; Huang, Shucheng; Iqbal, Muhammad Kashif; Li, Jiakui

    2017-08-01

    The present study has examined the virulence potential of Escherichia coli isolates harboring at least one virulence gene (associated with ExPEC or InPEC pathotype and belonging to different phylogenetic groups: A, B1, B2 or D), isolated from free ranging Tibetan yak feces. The E. coli isolates (n = 87) were characterized for different serogroups and a mouse model of subcutaneous-infection was used to envisage the virulence within these E. coli strains. Of the 87 E. coli isolates examined, 23% of the E. coli isolates caused lethal infections in a mouse model of subcutaneous infection and were classified as killer. Moreover, the majority of the killer strains belonged to phylogroup A (65%) and serogroup O60 or O101 (35%). Phylogroup B1, serogroups O60 and O101 were statistically associated with the killer status (P < 0.05). However, positive associations (OR >1) were observed between the killer status isolates and all other bacterial virulence traits. This study comprises the first report on the virulence potential of E. coli strains isolated from free-ranging Tibetan yaks feces. Our findings suggest that pathogenic E. coli of free ranging yaks is highly worrisome, as these feces are used as manures by farmers and therewith pose a health risk to humans upon exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Experimental tests of host-virus coevolution in natural killer yeast strains.

    PubMed

    Pieczynska, M D; Korona, R; De Visser, J A G M

    2017-04-01

    Fungi may carry cytoplasmic viruses that encode anticompetitor toxins. These so-called killer viruses may provide competitive benefits to their host, but also incur metabolic costs associated with viral replication, toxin production and immunity. Mechanisms responsible for the stable maintenance of these endosymbionts are insufficiently understood. Here, we test whether co-adaptation of host and killer virus underlies their stable maintenance in seven natural and one laboratory strain of the genus Saccharomyces. We employ cross-transfection of killer viruses, all encoding the K1-type toxin, to test predictions from host-virus co-adaptation. These tests support local adaptation of hosts and/or their killer viruses. First, new host-virus combinations have strongly reduced killing ability against a standard sensitive strain when compared with re-constructed native combinations. Second, viruses are more likely to be lost from new than from original hosts upon repeated bottlenecking or the application of stressful conditions. Third, host fitness is increased after the re-introduction of native viruses, but decreased after the introduction of new viruses. Finally, rather than a trade-off, original combinations show a positive correlation between killing ability and fitness. Together, these results suggest that natural yeast killer strains and their viruses have co-adapted, allowing the transition from a parasitic to a mutualistic symbiosis.

  9. Experimental Infections of the Reservoir Species Peromyscus leucopus with Diverse Strains of Borrelia burgdorferi, a Lyme Disease Agent

    PubMed Central

    Baum, Elisabeth; Hue, Fong; Barbour, Alan G.

    2012-01-01

    ABSTRACT The rodent Peromyscus leucopus is a major natural reservoir for the Lyme disease agent Borrelia burgdorferi and a host for its vector Ixodes scapularis. At various locations in northeastern United States 10 to 15 B. burgdorferi strains coexist at different prevalences in tick populations. We asked whether representative strains of high or low prevalence differed in their infections of P. leucopus. After 5 weeks of experimental infection of groups with each of 6 isolates, distributions and burdens of bacteria in tissues were measured by quantitative PCR, and antibodies to B. burgdorferi were evaluated by immunoblotting and protein microarray. All groups of animals were infected in their joints, ears, tails, and hearts, but overall spirochete burdens were lower in animals infected with low-prevalence strains. Animals were similar regardless of the infecting isolate in their levels of antibodies to whole cells, FlaB, BmpA, and DbpB proteins, and the conserved N-terminal region of the serotype-defining OspC proteins. But there were strain-specific antibody responses to full-length OspC and to plasmid-encoded VlsE, BBK07, and BBK12 proteins. Sequencing of additional VlsE genes revealed substantial diversity within some pairs of strains but near-identical sequences within other pairs, which otherwise differed in their ospC alleles. The presence or absence of full-length bbk07 and bbk12 genes accounted for the differences in antibody responses. We propose that for B. burgdorferi, there is selection in reservoir species for (i) sequence diversity, as for OspC and VlsE, and (ii) the presence or absence of polymorphisms, as for BBK07 and BBK12. PMID:23221801

  10. Calomys callosus chronically infected by Toxoplasma gondii clonal type II strain and reinfected by Brazilian strains is not able to prevent vertical transmission

    PubMed Central

    Franco, Priscila S.; da Silva, Neide M.; de Freitas Barbosa, Bellisa; de Oliveira Gomes, Angelica; Ietta, Francesca; Shwab, E. K.; Su, Chunlei; Mineo, José R.; Ferro, Eloisa A. V.

    2015-01-01

    Considering that Toxoplasma gondii has shown high genetic diversity in Brazil, the aim of this study was to determine whether Calomys callosus chronically infected by the ME-49 strain might be susceptible to reinfection by these Brazilian strains, including vertical transmission of the parasite. Survival curves were analyzed in non-pregnant females chronically infected with ME-49 and reinfected with the TgChBrUD1 or TgChBrUD2 strain, and vertical transmission was analyzed after reinfection of pregnant females with these same strains. On the 19th day of pregnancy (dop), placentas, uteri, fetuses, liver, spleen, and lung were processed for detection of the parasite. Blood samples were collected for humoral and cellular immune response analyses. All non-pregnant females survived after reinfection and no changes were observed in body weight and morbidity scores. In pregnant females, parasites were detected in the placentas of ME-49 chronically infected females and reinfected females, but were only detected in the fetuses of reinfected females. TgChBrUD2 reinfected females showed more impaired pregnancy outcomes, presenting higher numbers of animals with fetal loss and a higher resorption rate, in parallel with higher levels of pro-inflammatory cytokines and IgG2a subclass antibodies. Vertical transmission resulting from chronic infection of immunocompetent C. callosus is considered a rare event, being attributed instead to either reactivation or reinfection. That is, the pregnancy may be responsible for reactivation of the latent infection or the reinfection may promote T. gondii vertical transmission. Our results clearly demonstrate that, during pregnancy, protection against T. gondii can be breached after reinfection with parasites belonging to different genotypes, particularly when non-clonal strains are involved in this process and in this case the reinfection promoted vertical transmission of both type II and Brazilian T. gondii strains. PMID:25806028

  11. Experimental demonstration of a semi-brittle origin for crustal strain transients

    NASA Astrophysics Data System (ADS)

    Reber, J. E.; Lavier, L. L.; Hayman, N. W.

    2015-12-01

    Tectonic motions that give rise to destructive earthquakes and enigmatic transient slip events are commonly explained by friction laws that describe slip on fault surfaces and gouge-filled zones. Friction laws with the added effects of pore fluid pressure, shear heating, and chemical reactions as currently applied do not take into account that over a wide range of pressure and temperature conditions rocks deform following a complex mixed brittle-ductile rheology. In semi-brittle materials, such as polymineralic rocks, elasto-plastic and visco-elastic defamation can be observed simultaneously in different phases of the material. Field observations of such semi-brittle rocks at the mesoscale have shown that for a given range of composition, temperature, and pressure, the formation of fluid-filled brittle fractures and veins can precede and accompany the development of localized ductile flow. We propose that the coexistence of brittle and viscous behavior controls some of the physical characteristics of strain transients and slow slip events. Here we present results from shear experiments on semi-brittle rock analogues investigating the effect of yield stress on fracture propagation and connection, and how this can lead to reoccurring strain transients. During the experiments we monitor the evolution of fractures and flow as well as the force development in the system. We show that the nature of localized slip and flow in semi-brittle materials depends on the initiation and formation of mode I and II fractures and does not involve frictional behavior, supporting an alternative mechanism for the development of tectonic strain transients.

  12. An Experimental Technique for Developing Intermediate Strain Rates in Ductile Metals

    DTIC Science & Technology

    2008-03-01

    the test apparatus which is treated as a linear spring. Assuming a stress-strain relation given by Eε̇ = σ̇ + g(σ, ε) (2.24) where g(σ, ε) is a...and (c) [24] . . . . . . . . . 35 2.7. Schematic of Split Hopkinson Bar Tensile Test [38] . . . . . . . 41 2.8. Charpy Test Apparatus and Diagrams of...The ability to in- vestigate the dynamic response of structural metals with a relatively inexpensive test apparatus and a simple test procedure would

  13. Lucilia sericata strain from Colombia: Experimental colonization, life tables and evaluation of two artificial diets of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae), Bogotá, Colombia strain.

    PubMed

    Rueda, Luis C; Ortega, Luis G; Segura, Nidya A; Acero, Víctor M; Bello, Felio

    2010-01-01

    The objective of this work was to establish, under experimental laboratory conditions, a colony of Lucilia sericata, Bogotá-Colombia strain, to build life tables and evaluate two artificial diets. This blowfly is frequently used in postmortem interval studies and in injury treatment. The parental adult insects collected in Bogotá were maintained in cages at 22°C±1 average temperature, 60%±5 relative humidity and 12 h photoperiodicity. The blowflies were fed on two artificial diets that were evaluated over seven continuous generations. Reproductive and population parameters were assessed. The life cycle of the species was expressed in the number of days of the different stages: egg = 0.8±0.1, larvae I = 1.1±0.02, larvae II = 1.94±0.16, larvae III = 3.5±0.54, pupae = 6.55±0.47, male adult = 28.7±0.83 and female adult = 33.5±1.0. Total survival from egg stage to adult stage was 91.2% for diet 1, while for diet 2 this parameter was 40.5%. The lifetime reproductive output was 184.51±11.2 eggs per female. The population parameters, as well as the reproductive output of the blowflies that were assessed, showed relatively high values, giving evidence of the continuous increase of the strain over the different generations and making possible its maintenance as a stable colony that has lasted for more than two years.

  14. White and red blood cell picture in rabbits experimentally infected with strains of the rabbit haemorrhagic disease (RHD) virus without or with variable haemagglutination capacity.

    PubMed

    Niedźwiedzka-Rystwej, P; Tokarz-Deptuła, B; Deptuła, W

    2016-12-01

    The aim of the study was to establish if haemagglutination of rabbit haemorrhagic disease virus (RHDV) affects haematological picture of peripheral blood in rabbits and the pathogenicity of the virus. The study analyzed white and red blood cell picture in rabbits experimentally infected with two non-haemagglutinating (HA-) RHDV strains (Frankfurt and Asturias) and one strain with variable haemagglutination capacity (HA+/-) (Hagenow). Studies with HA- and HA +/- are rare and relate only to 4 HA- strains (2 RHDV: BLA and Rainham; 2 RHDVa: Pv97 and 9905) and 1 HA+/- RHDV strain: ŻD, where less changes in haematological indices and less pathogenicity were observed. We found that changes caused by HA- Frankfurt strain were related to the number of neutrophils and thrombocytes, while in HA- strain Asturias, in thrombocytes and leukocytes. Changes evoked by HA+/- Hagenow strain pertained to the number of eosinophils, thrombocytes, leukocytes, monocytes, and concentration of hemoglobin. Mortality caused by the Frankfurt strain was 100% between 36 and 48 h post infection (p.i.), while that caused by Asturias strain was 100% between 24 and 36 h p.i., and that observed in case of Hagenow strain was 90% between 36 and 48 h p.i. The changes in haematological picture caused by the HA- and HA+/- RHDV strains were less intensive than those found in case of the HA+ RHDV strains, which cannot be confirmed for pathogenicity, and is not in line with the existing hypothesis suggesting higher pathogenicity in HA+ viruses.

  15. Experimental study of steel welded joints localization with using fiber Bragg grating strain sensor

    NASA Astrophysics Data System (ADS)

    Harasim, Damian

    2015-12-01

    Optical sensing systems has a not weakening research and development in recent years. Because of its unique properties of being unsusceptible to electromagnetic interference, having wide range of operational temperature and having extreme small physical dimensions, optical fiber sensors has increasing acceptance. Fiber Bragg Gratings (FBG) is the most frequently used type of optical sensor types because of its huge multiplexing potential and potentiality of being embedded into composite material (e.g. in structural health monitoring) or attached into measured structure. Embedding or attaching FBG into an inhomogeneous environment, spectral characteristic of the sensing grating do not retain full symmetry, which is due to related differences in the distribution of the axial stress of the grating. When periodicity of the grating is constant, the peak of FBG reflection spectrum should be narrow and sharp. An inhomogeneous axial strain distribution will cause a distorsion in measured transmission or reflection spectrum. This paper shows an distorsions in FBG reflection spectrum measured from sensor attached on surface with welded joint. The sensor strain-to-wavelength shift processing characteristics obtained for homogeneous and welded steel samples were compared.

  16. Quantification of substrate and cellular strains in stretchable 3D cell cultures: an experimental and computational framework.

    PubMed

    González-Avalos, P; Mürnseer, M; Deeg, J; Bachmann, A; Spatz, J; Dooley, S; Eils, R; Gladilin, E

    2017-05-01

    The mechanical cell environment is a key regulator of biological processes . In living tissues, cells are embedded into the 3D extracellular matrix and permanently exposed to mechanical forces. Quantification of the cellular strain state in a 3D matrix is therefore the first step towards understanding how physical cues determine single cell and multicellular behaviour. The majority of cell assays are, however, based on 2D cell cultures that lack many essential features of the in vivo cellular environment. Furthermore, nondestructive measurement of substrate and cellular mechanics requires appropriate computational tools for microscopic image analysis and interpretation. Here, we present an experimental and computational framework for generation and quantification of the cellular strain state in 3D cell cultures using a combination of 3D substrate stretcher, multichannel microscopic imaging and computational image analysis. The 3D substrate stretcher enables deformation of living cells embedded in bead-labelled 3D collagen hydrogels. Local substrate and cell deformations are determined by tracking displacement of fluorescent beads with subsequent finite element interpolation of cell strains over a tetrahedral tessellation. In this feasibility study, we debate diverse aspects of deformable 3D culture construction, quantification and evaluation, and present an example of its application for quantitative analysis of a cellular model system based on primary mouse hepatocytes undergoing transforming growth factor (TGF-β) induced epithelial-to-mesenchymal transition. © 2017 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

  17. Experimental and analytical program to determine strains in 737 LAP splice joints subjected to normal fuselage pressurization loads

    SciTech Connect

    Roach, D.P.; Jeong, D.Y.

    1996-02-01

    The Federal Aviation Administration Technical Center (FAATC) has initiated several research projects to assess the structural integrity of the aging commercial aircraft fleet. One area of research involves the understanding of a phenomenon known as ``Widespread Fatigue Damage`` or WFD, which refers to a type of multiple element cracking that degrades the damage tolerance capability of an aircraft structure. Research on WFD has been performed both experimentally and analytically including finite element modeling of fuselage lap splice joints by the Volpe Center. Fuselage pressurization tests have also been conducted at the FAA`s Airworthiness Assurance NDI Validation Center (AANC) to obtain strain gage data from select locations on the FAA/AANC 737 Transport Aircraft Test Bed. One-hundred strain channels were used to monitor five different lap splice bays including the fuselage skin and substructure elements. These test results have been used to evaluate the accuracy of the analytical models and to support general aircraft analysis efforts. This paper documents the strain fields measured during the AANC tests and successfully correlates the results with analytical predictions.

  18. [Discriminating concentrations for three insecticides used in public health in a Lutzomyia longipalpis experimental strain from Colombia].

    PubMed

    Marceló, Catalina; Cabrera, Olga Lucía; Santamaría, Erika

    2014-01-01

    In Colombia, periurban populations of Lutzomyia longipalpis , vector of the causative agent of visceral leishmaniasis in the upper and middle valley of the Magdalena River, may be exposed to insecticide applications with different purposes. Thus, it is important to begin a susceptibility surveillance of this species to insecticides. To determine indicators of susceptibility to three insecticides habitually used in public health, such as malathion, deltamethrin and lambda-cyhalothrin in an experimental strain of L. longipalpis . We used the method proposed by the Centers for Disease Control and Prevention. Groups of 10 to 15 unfed females were exposed to different concentrations of the insecticides using 250 ml glass bottles as test chambers. Mortality was registered every five minutes for an hour. Diagnostic concentrations and lethal times for each insecticide were calculated. In the evaluated L. longipalpis strain, the diagnostic concentrations and times were 75 µg/ml and 25 minutes for malathion, 10 µg/ml and 35 minutes for deltamethrin, and 15 µg/ml during 30 minutes for lambda-cyhalothrin. Baseline data over mortality response to three insecticides were established in a susceptibility strain of L. longipalpis vector. These indicators will allow establishing comparisons with populations of L. longipalpis exposed regularly or sporadically to chemical control measures to detect changes in their resistance to these insecticides.

  19. Efficacy of Ampicillin plus Ceftriaxone in Treatment of Experimental Endocarditis Due to Enterococcus faecalis Strains Highly Resistant to Aminoglycosides

    PubMed Central

    Gavaldà, Joan; Torres, Carmen; Tenorio, Carmen; López, Pedro; Zaragoza, Myriam; Capdevila, Josep A.; Almirante, Benito; Ruiz, Fernanda; Borrell, Nuria; Gomis, Xavier; Pigrau, Carles; Baquero, Fernando; Pahissa, Albert

    1999-01-01

    The purpose of this work was to evaluate the in vitro possibilities of ampicillin-ceftriaxone combinations for 10 Enterococcus faecalis strains with high-level resistance to aminoglycosides (HLRAg) and to assess the efficacy of ampicillin plus ceftriaxone, both administered with humanlike pharmacokinetics, for the treatment of experimental endocarditis due to HLRAg E. faecalis. A reduction of 1 to 4 dilutions in MICs of ampicillin was obtained when ampicillin was combined with a fixed subinhibitory ceftriaxone concentration of 4 μg/ml. This potentiating effect was also observed by the double disk method with all 10 strains. Time-kill studies performed with 1 and 2 μg of ampicillin alone per ml or in combination with 5, 10, 20, 40, and 60 μg of ceftriaxone per ml showed a ≥2 log10 reduction in CFU per milliliter with respect to ampicillin alone and to the initial inoculum for all 10 E. faecalis strains studied. This effect was obtained for seven strains with the combination of 2 μg of ampicillin per ml plus 10 μg of ceftriaxone per ml and for six strains with 5 μg of ceftriaxone per ml. Animals with catheter-induced endocarditis were infected intravenously with 108 CFU of E. faecalis V48 or 105 CFU of E. faecalis V45 and were treated for 3 days with humanlike pharmacokinetics of 2 g of ampicillin every 4 h, alone or combined with 2 g of ceftriaxone every 12 h. The levels in serum and the pharmacokinetic parameters of the humanlike pharmacokinetics of ampicillin or ceftriaxone in rabbits were similar to those found in humans treated with 2 g of ampicillin or ceftriaxone intravenously. Results of the therapy for experimental endocarditis caused by E. faecalis V48 or V45 showed that the residual bacterial titers in aortic valve vegetations were significantly lower in the animals treated with the combinations of ampicillin plus ceftriaxone than in those treated with ampicillin alone (P < 0.001). The combination of ampicillin and ceftriaxone showed in vitro and

  20. Determining the Mechanical Constitutive Properties of Metals as Function of Strain Rate and temperature: A Combined Experimental and Modeling Approach

    SciTech Connect

    Ian Robertson

    2007-04-28

    Development and validation of constitutive models for polycrystalline materials subjected to high strain-rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions. To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be integrated fully with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experiment is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models. One aspect of the program involves the direct observation of specific mechanisms of micro-plasticity, as these indicate the boundary value problem that should be addressed. This focus on the pre-yield region in the quasi-static effort (the elasto-plastic transition) is also a tractable one from an

  1. Experimental infection of dogs with a Brazilian strain of Rickettsia rickettsii: clinical and laboratory findings.

    PubMed

    Piranda, Eliane M; Faccini, João Luis H; Pinter, Adriano; Saito, Tais B; Pacheco, Richard C; Hagiwara, Mitika K; Labruna, Marcelo B

    2008-11-01

    The bacterium Rickettsia rickettsii is the etiological agent of an acute, severe disease called Rocky Mountain spotted fever in the United States or Brazilian spotted fever (BSF) in Brazil. In addition to these two countries, the disease has also been reported to affect humans in Mexico, Costa Rica, Panama, Colombia and Argentina. Like humans, dogs are also susceptible to R. rickettsii infection. However, despite the wide distribution of R. rickettsii in the Western Hemisphere, reports of R. rickettsii-induced illness in dogs has been restricted to the United States. The present study evaluated the pathogenicity for dogs of a South American strain of R. rickettsii. Three groups of dogs were evaluated: group 1 (G1) was inoculated ip with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and the control group (G3) was infested by uninfected ticks. During the study, no clinical abnormalities, Rickettsia DNA or R. rickettsii-reactive antibodies were detected in G3. In contrast, all G1 and G2 dogs developed signs of rickettsial infection, i.e., fever, lethargy, anorexia, ocular lesions, thrombocytopenia, anemia and detectable levels of Rickettsia DNA and R. rickettsii-reactive antibodies in their blood. Rickettsemia started 3-8 days after inoculation or tick infestation and lasted for 3-13 days. Our results indicate that a Brazilian strain of R. rickettsii is pathogenic for dogs, suggesting that canine clinical illness due to R. rickettsii has been unreported in Brazil and possibly in the other South American countries where BSF has been reported among humans.

  2. Sex-independent suppression of experimental inflammatory pain by minocycline in two mouse strains.

    PubMed

    Bastos, Leandro F S; Prazeres, Júlia D M; Godin, Adriana M; Menezes, Raquel R; Soares, Darly G; Ferreira, Wallace C; Dutra, Marcela M G B; Machado, Renes R; Coelho, Márcio M

    2013-10-11

    The research on sex differences in nociception and antinociception as well as sex and gender differences in pain and analgesia is a maturing field. There is a vast literature showing experimental and clinical pain suppressive effects induced by minocycline, especially in inflammatory pain. However, as far as we know, possible qualitative or quantitative sex differences in those effects remained to be examined. By employing the formalin test, which has two phases of experimental pain behavior that models nociceptive pain (i.e., first phase) and inflammatory pain (i.e., second phase), we initially evaluated the effect induced by minocycline in female or male C57BL/6 mice. The treatment reduced the second phase of licking behavior in both females and males, and the effects were quantitatively similar in both sexes. Likewise, the same sex-independent effect was observed in Swiss mice, suggesting a genotype-unspecific sex-independent effect. While minocycline is already being tested in clinical trials, this appears to be the first preclinical investigation of sex differences in the experimental pain suppressive effects induced by this widely studied drug. The independence of sex in the antinociceptive effect induced by minocycline may be hopefully translated to gender-independent analgesic effects, which would be surely promising in a therapeutic paradigm. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  3. Experimental verification of the Neuber relation at room and elevated temperatures. M.S. Thesis; [to predict stress-strain behavior in notched specimens of hastelloy x

    NASA Technical Reports Server (NTRS)

    Lucas, L. J.

    1982-01-01

    The accuracy of the Neuber equation at room temperature and 1,200 F as experimentally determined under cyclic load conditions with hold times. All strains were measured with an interferometric technique at both the local and remote regions of notched specimens. At room temperature, strains were obtained for the initial response at one load level and for cyclically stable conditions at four load levels. Stresses in notched members were simulated by subjecting smooth specimens to he same strains as were recorded on the notched specimen. Local stress-strain response was then predicted with excellent accuracy by subjecting a smooth specimen to limits established by the Neuber equation. Data at 1,200 F were obtained with the same experimental techniques but only in the cyclically stable conditions. The Neuber prediction at this temperature gave relatively accurate results in terms of predicting stress and strain points.

  4. Experimental single-strain mobilomics reveals events that shape pathogen emergence

    PubMed Central

    Schoeniger, Joseph S.; Hudson, Corey M.; Bent, Zachary W.; Sinha, Anupama; Williams, Kelly P.

    2016-01-01

    Virulence genes on mobile DNAs such as genomic islands (GIs) and plasmids promote bacterial pathogen emergence. Excision is an early step in GI mobilization, producing a circular GI and a deletion site in the chromosome; circular forms are also known for some bacterial insertion sequences (ISs). The recombinant sequence at the junctions of such circles and deletions can be detected sensitively in high-throughput sequencing data, using new computational methods that enable empirical discovery of mobile DNAs. For the rich mobilome of a hospital Klebsiella pneumoniae strain, circularization junctions (CJs) were detected for six GIs and seven IS types. Our methods revealed differential biology of multiple mobile DNAs, imprecision of integrases and transposases, and differential activity among identical IS copies for IS26, ISKpn18 and ISKpn21. Using the resistance of circular dsDNA molecules to exonuclease, internally calibrated with the native plasmids, showed that not all molecules bearing GI CJs were circular. Transpositions were also detected, revealing replicon preference (ISKpn18 prefers a conjugative IncA/C2 plasmid), local action (IS26), regional preferences, selection (against capsule synthesis) and IS polarity inversion. Efficient discovery and global characterization of numerous mobile elements per experiment improves accounting for the new gene combinations that arise in emerging pathogens. PMID:27378783

  5. Experimental infections of the reservoir species Peromyscus leucopus with diverse strains of Borrelia burgdorferi, a Lyme disease agent.

    PubMed

    Baum, Elisabeth; Hue, Fong; Barbour, Alan G

    2012-12-04

    The rodent Peromyscus leucopus is a major natural reservoir for the Lyme disease agent Borrelia burgdorferi and a host for its vector Ixodes scapularis. At various locations in northeastern United States 10 to 15 B. burgdorferi strains coexist at different prevalences in tick populations. We asked whether representative strains of high or low prevalence differed in their infections of P. leucopus. After 5 weeks of experimental infection of groups with each of 6 isolates, distributions and burdens of bacteria in tissues were measured by quantitative PCR, and antibodies to B. burgdorferi were evaluated by immunoblotting and protein microarray. All groups of animals were infected in their joints, ears, tails, and hearts, but overall spirochete burdens were lower in animals infected with low-prevalence strains. Animals were similar regardless of the infecting isolate in their levels of antibodies to whole cells, FlaB, BmpA, and DbpB proteins, and the conserved N-terminal region of the serotype-defining OspC proteins. But there were strain-specific antibody responses to full-length OspC and to plasmid-encoded VlsE, BBK07, and BBK12 proteins. Sequencing of additional VlsE genes revealed substantial diversity within some pairs of strains but near-identical sequences within other pairs, which otherwise differed in their ospC alleles. The presence or absence of full-length bbk07 and bbk12 genes accounted for the differences in antibody responses. We propose that for B. burgdorferi, there is selection in reservoir species for (i) sequence diversity, as for OspC and VlsE, and (ii) the presence or absence of polymorphisms, as for BBK07 and BBK12. Humans are dead-end hosts for Borrelia agents of Lyme disease (LD), and, thus, irrelevant for the pathogens' maintenance. Many reports of human cases and laboratory mouse infections exist, but less is known about infection and immunity in natural reservoirs, such as the rodent Peromyscus leucopus. We observed that high- and low

  6. Contributed Review: Experimental characterization of inverse piezoelectric strain in GaN HEMTs via micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bagnall, Kevin R.; Wang, Evelyn N.

    2016-06-01

    Micro-Raman thermography is one of the most popular techniques for measuring local temperature rise in gallium nitride (GaN) high electron mobility transistors with high spatial and temporal resolution. However, accurate temperature measurements based on changes in the Stokes peak positions of the GaN epitaxial layers require properly accounting for the stress and/or strain induced by the inverse piezoelectric effect. It is common practice to use the pinched OFF state as the unpowered reference for temperature measurements because the vertical electric field in the GaN buffer that induces inverse piezoelectric stress/strain is relatively independent of the gate bias. Although this approach has yielded temperature measurements that agree with those derived from the Stokes/anti-Stokes ratio and thermal models, there has been significant difficulty in quantifying the mechanical state of the GaN buffer in the pinched OFF state from changes in the Raman spectra. In this paper, we review the experimental technique of micro-Raman thermography and derive expressions for the detailed dependence of the Raman peak positions on strain, stress, and electric field components in wurtzite GaN. We also use a combination of semiconductor device modeling and electro-mechanical modeling to predict the stress and strain induced by the inverse piezoelectric effect. Based on the insights gained from our electro-mechanical model and the best values of material properties in the literature, we analyze changes in the E2 high and A1 (LO) Raman peaks and demonstrate that there are major quantitative discrepancies between measured and modeled values of inverse piezoelectric stress and strain. We examine many of the hypotheses offered in the literature for these discrepancies but conclude that none of them satisfactorily resolves these discrepancies. Further research is needed to determine whether the electric field components could be affecting the phonon frequencies apart from the inverse

  7. Contributed Review: Experimental characterization of inverse piezoelectric strain in GaN HEMTs via micro-Raman spectroscopy

    SciTech Connect

    Bagnall, Kevin R.; Wang, Evelyn N.

    2016-06-15

    Micro-Raman thermography is one of the most popular techniques for measuring local temperature rise in gallium nitride (GaN) high electron mobility transistors with high spatial and temporal resolution. However, accurate temperature measurements based on changes in the Stokes peak positions of the GaN epitaxial layers require properly accounting for the stress and/or strain induced by the inverse piezoelectric effect. It is common practice to use the pinched OFF state as the unpowered reference for temperature measurements because the vertical electric field in the GaN buffer that induces inverse piezoelectric stress/strain is relatively independent of the gate bias. Although this approach has yielded temperature measurements that agree with those derived from the Stokes/anti-Stokes ratio and thermal models, there has been significant difficulty in quantifying the mechanical state of the GaN buffer in the pinched OFF state from changes in the Raman spectra. In this paper, we review the experimental technique of micro-Raman thermography and derive expressions for the detailed dependence of the Raman peak positions on strain, stress, and electric field components in wurtzite GaN. We also use a combination of semiconductor device modeling and electro-mechanical modeling to predict the stress and strain induced by the inverse piezoelectric effect. Based on the insights gained from our electro-mechanical model and the best values of material properties in the literature, we analyze changes in the E{sub 2} high and A{sub 1} (LO) Raman peaks and demonstrate that there are major quantitative discrepancies between measured and modeled values of inverse piezoelectric stress and strain. We examine many of the hypotheses offered in the literature for these discrepancies but conclude that none of them satisfactorily resolves these discrepancies. Further research is needed to determine whether the electric field components could be affecting the phonon frequencies apart from the

  8. Contributed Review: Experimental characterization of inverse piezoelectric strain in GaN HEMTs via micro-Raman spectroscopy.

    PubMed

    Bagnall, Kevin R; Wang, Evelyn N

    2016-06-01

    Micro-Raman thermography is one of the most popular techniques for measuring local temperature rise in gallium nitride (GaN) high electron mobility transistors with high spatial and temporal resolution. However, accurate temperature measurements based on changes in the Stokes peak positions of the GaN epitaxial layers require properly accounting for the stress and/or strain induced by the inverse piezoelectric effect. It is common practice to use the pinched OFF state as the unpowered reference for temperature measurements because the vertical electric field in the GaN buffer that induces inverse piezoelectric stress/strain is relatively independent of the gate bias. Although this approach has yielded temperature measurements that agree with those derived from the Stokes/anti-Stokes ratio and thermal models, there has been significant difficulty in quantifying the mechanical state of the GaN buffer in the pinched OFF state from changes in the Raman spectra. In this paper, we review the experimental technique of micro-Raman thermography and derive expressions for the detailed dependence of the Raman peak positions on strain, stress, and electric field components in wurtzite GaN. We also use a combination of semiconductor device modeling and electro-mechanical modeling to predict the stress and strain induced by the inverse piezoelectric effect. Based on the insights gained from our electro-mechanical model and the best values of material properties in the literature, we analyze changes in the E2 high and A1 (LO) Raman peaks and demonstrate that there are major quantitative discrepancies between measured and modeled values of inverse piezoelectric stress and strain. We examine many of the hypotheses offered in the literature for these discrepancies but conclude that none of them satisfactorily resolves these discrepancies. Further research is needed to determine whether the electric field components could be affecting the phonon frequencies apart from the inverse

  9. Experimental single-strain mobilomics reveals events that shape pathogen emergence

    DOE PAGES

    Schoeniger, Joseph S.; Hudson, Corey M.; Bent, Zachary W.; ...

    2016-07-04

    Virulence and resistance genes carried on mobile DNAs such as genomic islands (GIs) and plasmids promote bacterial pathogen emergence. An early step in the mobilization of GIs is their excision, which produces both a circular form of the GI and a deletion site in the chromosome; circular forms have also been described for some bacterial insertion sequences (ISs). We demonstrate that the recombinant sequence produced at the junction of such circles, and their corresponding deletion sites, can be detected sensitively in high throughput sequencing data, using new computational methods that enable empirical discovery of new mobile DNAs. Applied to themore » rich mobilome of a single strain (Kpn2146) of the emerging multidrug-resistant pathogen Klebsiella pneumoniae, our approach detected circular junctions for six GIs and seven IS types (several of the latter not previously known to circularize). Our methods further revealed differential biology of multiple mobile DNAs, imprecision of integrases and transposases, and differential activity among identical IS copies for IS26, ISKpn18 and ISKpn21. Exonuclease was used to enrich for circular dsDNA molecules, and internal calibration with the native Kpn2146 plasmids showed that not all molecules bearing GI and IS circular junctions were circular dsDNAs. Transposition events were also detected, revealing replicon preference (ISKpn18 preferring a conjugative IncA/C2 plasmid), local action (IS26), regional preferences, selection (against capsule synthesis), and left-right IS end swapping. Efficient discovery and global characterization of numerous mobile elements per experiment will allow detailed accounting of bacterial evolution, explaining the new gene combinations that arise in emerging pathogens.« less

  10. Experimental single-strain mobilomics reveals events that shape pathogen emergence

    SciTech Connect

    Schoeniger, Joseph S.; Hudson, Corey M.; Bent, Zachary W.; Sinha, Anupama; Williams, Kelly P.

    2016-07-04

    Virulence and resistance genes carried on mobile DNAs such as genomic islands (GIs) and plasmids promote bacterial pathogen emergence. An early step in the mobilization of GIs is their excision, which produces both a circular form of the GI and a deletion site in the chromosome; circular forms have also been described for some bacterial insertion sequences (ISs). We demonstrate that the recombinant sequence produced at the junction of such circles, and their corresponding deletion sites, can be detected sensitively in high throughput sequencing data, using new computational methods that enable empirical discovery of new mobile DNAs. Applied to the rich mobilome of a single strain (Kpn2146) of the emerging multidrug-resistant pathogen Klebsiella pneumoniae, our approach detected circular junctions for six GIs and seven IS types (several of the latter not previously known to circularize). Our methods further revealed differential biology of multiple mobile DNAs, imprecision of integrases and transposases, and differential activity among identical IS copies for IS26, ISKpn18 and ISKpn21. Exonuclease was used to enrich for circular dsDNA molecules, and internal calibration with the native Kpn2146 plasmids showed that not all molecules bearing GI and IS circular junctions were circular dsDNAs. Transposition events were also detected, revealing replicon preference (ISKpn18 preferring a conjugative IncA/C2 plasmid), local action (IS26), regional preferences, selection (against capsule synthesis), and left-right IS end swapping. Efficient discovery and global characterization of numerous mobile elements per experiment will allow detailed accounting of bacterial evolution, explaining the new gene combinations that arise in emerging pathogens.

  11. Recovery of Toxoplasma gondii DNA in experimentally mummified skin and bones: Prospects for paleoparasitological studies to unveil the origin of toxoplasmosis.

    PubMed

    Leles, Daniela; Lobo, Amanda; Rhodes, Taís; Millar, Patrícia Riddell; Amendoeira, Maria Regina Reis; Araújo, Adauto

    2016-09-01

    Paleoparasitology studies parasite infections by finding the parasites' remains in preserved organic remains such as natural or artificial mummy tissues, skeletons, teeth, and coprolites, among others. However, some currently important infections like toxoplasmosis have not been studied by paleoparasitology. The reasons include this parasite's complex life cycle, the resulting difficulties in locating this protozoan in the intermediate host tissues, and the limitation of coprolite studies to felines, the protozoan's definitive host. The current study thus aimed to produce an experimental model for molecular diagnosis of toxoplasmosis, prioritizing its study in bones and skin, the most abundant materials in archeological collections and sites. The study demonstrated the feasibility of recovering Toxoplasma gondii DNA from desiccated material, including bones and skin, in experimental models both with circulating tachyzoites (RH strain), characteristic of acute infection, and with cysts (ME49 cystogenic strain), characteristic of chronic infection. At present, most individuals with T. gondii infection are in the chronic phase, and the same was probably true in the past. The current study thus expands the odds of finding the parasite in archeological material, enhanced by the nature of the material in which the diagnosis was made. Finding the parasite may help answer questions that are widely debated in the literature on this protozoan's origin (Old World versus New World). In addition, when conditions do not allow ideal storage of samples for molecular tests, the methodology creates the possibility of testing oven-dried samples transported at room temperature.

  12. In situ determination of alveolar septal strain, stress and effective Young's modulus: an experimental/computational approach

    PubMed Central

    Wu, You

    2014-01-01

    Alveolar septa, which have often been modeled as linear elements, may distend due to inflation-induced reduction in slack or increase in tissue stretch. The distended septum supports tissue elastic and interfacial forces. An effective Young's modulus, describing the inflation-induced relative displacement of septal end points, has not been determined in situ for lack of a means of determining the forces supported by septa in situ. Here we determine such forces indirectly according to Mead, Takishima, and Leith's classic lung mechanics analysis (J Appl Physiol 28: 596–608, 1970), which demonstrates that septal connections transmit the transpulmonary pressure, PTP, from the pleural surface to interior regions. We combine experimental septal strain determination and computational stress determination, according to Mead et al., to calculate effective Young's modulus. In the isolated, perfused rat lung, we label the perfusate with fluorescence to visualize the alveolar septa. At eight PTP values around a ventilation loop between 4 and 25 cmH2O, and upon total deflation, we image the same region by confocal microscopy. Within an analysis region, we measure septal lengths. Normalizing by unstressed lengths at total deflation, we calculate septal strains for all PTP > 0 cmH2O. For the static imaging conditions, we computationally model application of PTP to the boundary of the analysis region and solve for septal stresses by least squares fit of an overdetermined system. From group septal strain and stress values, we find effective septal Young's modulus to range from 1.2 × 105 dyn/cm2 at low PTP to 1.4 × 106 dyn/cm2 at high PTP. PMID:24951778

  13. In situ determination of alveolar septal strain, stress and effective Young's modulus: an experimental/computational approach.

    PubMed

    Perlman, Carrie E; Wu, You

    2014-08-15

    Alveolar septa, which have often been modeled as linear elements, may distend due to inflation-induced reduction in slack or increase in tissue stretch. The distended septum supports tissue elastic and interfacial forces. An effective Young's modulus, describing the inflation-induced relative displacement of septal end points, has not been determined in situ for lack of a means of determining the forces supported by septa in situ. Here we determine such forces indirectly according to Mead, Takishima, and Leith's classic lung mechanics analysis (J Appl Physiol 28: 596-608, 1970), which demonstrates that septal connections transmit the transpulmonary pressure, PTP, from the pleural surface to interior regions. We combine experimental septal strain determination and computational stress determination, according to Mead et al., to calculate effective Young's modulus. In the isolated, perfused rat lung, we label the perfusate with fluorescence to visualize the alveolar septa. At eight PTP values around a ventilation loop between 4 and 25 cmH2O, and upon total deflation, we image the same region by confocal microscopy. Within an analysis region, we measure septal lengths. Normalizing by unstressed lengths at total deflation, we calculate septal strains for all PTP > 0 cmH2O. For the static imaging conditions, we computationally model application of PTP to the boundary of the analysis region and solve for septal stresses by least squares fit of an overdetermined system. From group septal strain and stress values, we find effective septal Young's modulus to range from 1.2 × 10(5) dyn/cm(2) at low P(TP) to 1.4 × 10(6) dyn/cm(2) at high P(TP).

  14. Comparative pathogenicity study of ten different betanodavirus strains in experimentally infected European sea bass, Dicentrarchus labrax (L.).

    PubMed

    Vendramin, N; Toffan, A; Mancin, M; Cappellozza, E; Panzarin, V; Bovo, G; Cattoli, G; Capua, I; Terregino, C

    2014-04-01

    Viral encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN), is a severe pathological condition caused by RNA viruses belonging to the Nodaviridae family, genus Betanodavirus. The disease, described in more than 50 fish species worldwide, is considered as the most serious viral threat affecting marine farmed species in the Mediterranean region, thus representing one of the bottlenecks for further development of the aquaculture industry. To date, four different genotypes have been identified, namely red-spotted grouper nervous necrosis virus (RGNNV), striped jack nervous necrosis virus (SJNNV), tiger puffer nervous necrosis virus and barfin flounder nervous necrosis virus, with the RGNNV genotype appearing as the most widespread in the Mediterranean region, although SJNNV-type strains and reassortant viruses have also been reported. The existence of these genetically different strains could be the reason for the differences in mortality observed in the field. However, very little experimental data are available on the pathogenicity of these viruses in farmed fish. Therefore, in this study, the pathogenicity of 10 isolates has been assessed with an in vivo trial. The investigation was conducted using the European sea bass, the first target fish species for the disease in the Mediterranean basin. Naive fish were challenged by immersion and clinical signs and mortality were recorded for 68 days; furthermore, samples collected at selected time points were analysed to evaluate the development of the infection. Finally, survivors were weighed to estimate the growth reduction. The statistically supported results obtained in this study demonstrated different pathogenicity patterns, underlined the potential risk represented by different strains in the transmission of the infection to highly susceptible species and highlighted the indirect damage caused by a clinical outbreak of VER/VNN.

  15. Experimental infection of nontarget species of rodents and birds with Brucella abortus strain RB51 vaccine

    USGS Publications Warehouse

    Januszewski, M.C.; Olsen, S.C.; McLean, R.G.; Clark, L.; Rhyan, Jack C.

    2001-01-01

    The Brucella abortus vaccine strain RB51 (SRB51) is being considered for use in the management of bnucellosis in wild bison (Bison bison) and elk (Cervus elaphus) populations in the Greater Yellowstone Area (USA). Evaluation of the vaccines safety in non-target species was considered necessary prior to field use. Between June 1998 and December 1999, ground squirrels (Spermophilus richardsonii, n = 21), deer mice (Peromyscus maniculatus, n = 14), prairie voles (Microtus ochrogaster, n = 21), and ravens (Corvus corax, n = 13) were orally inoculated with SRB51 or physiologic saline. Oral and rectal swabs and blood samples were collected for bacteriologic evaluation. Rodents were necropsied at 8 to 10 wk and 12 to 21 wk post inoculation (PI), and ravens at 7 and 11 wk PI. Spleen, liver and reproductive tissues were collected for bacteriologic and histopathologic evaluation. No differences in clinical signs, appetite, weight loss or gain, or activity were observed between saline- and SRB51-inoculated animals in all four species. Oral and rectal swabs from all species were negative throughout the study. In tissues obtained from SRB51-inoculated animals, the organism was isolated from six of seven (86%) ground squirrels, one of six (17%) deer mice, none of seven voles, and one of five (20%) ravens necropsied at 8, 8, 10, and 7 wk PI, respectively. Tissues from four of seven (57%) SRB51-inoculated ground squirrels were culture positive for the organism 12 wk PI; SRB51 was not recovered from deer mice, voles. or ravens necropsied 12, 21, or 11 wk, respectively, PI. SRB51 was not recovered from saline-inoculated ground squirrels, deer mice, or voles at any time but was recovered from one saline-inoculated raven at necropsy, 7 wk PI, likely attributable to contact with SRB51-inoculated ravens in an adjacent aviary room. Spleen was time primary tissue site of colonization in ground squirrels, followed by the liver and reproductive organs. The results indicate oral exposure to

  16. Experimental Comparison of Tantalum Material Strength between Single Crystal [100] and [111] Samples at High Pressure and Strain Rates

    NASA Astrophysics Data System (ADS)

    Plechaty, Christopher; Park, Hye-Sook; Cavallo, Rob; Rudd, Robert; Prisbrey, Shon; Maddox, Brian; Wehrenberg, Christopher; May, Mark; Remington, Bruce

    2013-06-01

    Experiments were performed using the OMEGA laser to investigate the strength difference between single crystal [100] and [111] Ta samples at high pressure (1 Mbar), and high strain rates (106- 108 s-1) . To achieve these pressures and strain rates in experiment without melting the sample, a quasi-isentropic drive was employed to drive the growth of pre-imposed sinusoidal perturbations on the surface of the Ta samples, via the Rayleigh-Taylor (RT) instability. By measuring the ripple amplitude using face-on high energy (~22 KeV) radiography, the strength of the Ta sample is inferred from the amount of RT growth observed. Under these experimental conditions, the Ta material strength can be modeled by the Multiscale (MS) model, developed at LLNL. The value of the ``Taylor Factor'' (a MS model parameter), is thought to vary for [100] and [111] crystal orientations. To investigate this difference under these conditions, a comparison of the ripple growth was performed on the two samples for the same shot and drive conditions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Influence of the strain path on crash properties of a crash-box structure by experimental and numerical approaches

    NASA Astrophysics Data System (ADS)

    Durrenberger, L.; Even, D.; Molinari, A.; Rusinek, A.

    2006-08-01

    In order to reduce the gas emission without decreasing the passengers safety, the UHSS (Ultra High Strength Steel) steels are more and more used in the automotive industry. The very high mechanical characteristics of these steels allow to reduce the car weight thanks to the thickness reduction of the structure parts. The aim of this study is to analyse the plastic pre-strain effect (forming) on the crash properties of a crash-box structure. In order to achieve this goal, experimental rheological tests have been performed by combining quasi-static tensile tests followed by dynamic tensile test (8.10 - 3 s - 1 ≤ dot{\\varepsilon} ≤ 1000 s - 1) for a TRIP steel produced by ARCELOR. The combination of these results allows to obtain a better understanding of the steel behaviour in dynamic loading under different strain paths. All these information are necessary for an efficient simulation of crash test by including a pertinent material response. A special attention is given to the influence of the previous forming process on the dynamical response of crash boxes.

  18. Experimental Identification of Actinobacillus pleuropneumoniae Strains L20 and JL03 Heptosyltransferases, Evidence for a New Heptosyltransferase Signature Sequence

    PubMed Central

    Merino, Susana; Knirel, Yuriy A.; Regué, Miguel; Tomás, Juan M.

    2013-01-01

    We experimentally identified the activities of six predicted heptosyltransferases in Actinobacillus pleuropneumoniae genome serotype 5b strain L20 and serotype 3 strain JL03. The initial identification was based on a bioinformatic analysis of the amino acid similarity between these putative heptosyltrasferases with others of known function from enteric bacteria and Aeromonas. The putative functions of all the Actinobacillus pleuropneumoniae heptosyltrasferases were determined by using surrogate LPS acceptor molecules from well-defined A. hydrophyla AH-3 and A. salmonicida A450 mutants. Our results show that heptosyltransferases APL_0981 and APJL_1001 are responsible for the transfer of the terminal outer core D-glycero-D-manno-heptose (D,D-Hep) residue although they are not currently included in the CAZY glycosyltransferase 9 family. The WahF heptosyltransferase group signature sequence [S(T/S)(GA)XXH] differs from the heptosyltransferases consensus signature sequence [D(TS)(GA)XXH], because of the substitution of D261 for S261, being unique. PMID:23383222

  19. Pathogenicity of three type 2 porcine reproductive and respiratory syndrome virus strains in experimentally inoculated pregnant gilts.

    PubMed

    Ladinig, Andrea; Detmer, Susan E; Clarke, Kyle; Ashley, Carolyn; Rowland, Raymond R R; Lunney, Joan K; Harding, John C S

    2015-05-04

    Mechanisms of reproductive failure resulting from infection with porcine reproductive and respiratory syndrome virus (PRRSV) are still poorly understood. Presented herein are the results of a side-by-side evaluation of the pathogenicity of three type 2 PRRSV strains in a reproductive model, from a pilot study used to develop experimental conditions and laboratory methods for a larger experiment. Pregnant gilts were experimentally infected with PRRSV at gestation day 85 or served as uninfected negative controls. After 21 days, all gilts and fetuses were necropsied. Clinical signs, litter outcome, viral load, cytokine levels, and pathology were compared from samples collected among pigs exposed to the three PRRSV strains. Based on differences in histologic lesions, and fetal weights, and numeric differences in gilt serum cytokine levels, litter outcome and virus replication in fetal tissues KS06-483 appeared less virulent than NVSL 97-7895 and KS06-72109 isolates. Levels of chemokine ligand 2 (CCL2), interferon alpha (IFNα), and interferon gamma (IFNγ) were increased in PPRRSV-infected compared to non-infected gilts (0.01 > P < 0.06). Inoculation with NVSL 97-7895 induced higher levels of all three cytokines. All three PRRSV isolates were able to induce high mean viral load in individual litters, which was closely related to the proportion of PRRSV positive fetuses in the litter. Viral load in fetal samples was also positively associated with viral load at the maternal-fetal interface. All but one dead fetus were positive for PRRSV RNA, and higher concentrations of PRRSV RNA in fetal thymus increased the odds of fetal death. Our results suggest that virus replication in fetal tissues and the maternal-fetal interface, but not in other gilt tissues, are important for the outcome of reproductive PRRS. Additionally, our data indicate that umbilical lesions decreased corresponding to the use of pentobarbital sedation prior to euthanasia of pregnant gilts by captive bolt

  20. Interfacial kinematics and governing mechanisms under the influence of high strain rate impact conditions: Numerical computations of experimental observations

    NASA Astrophysics Data System (ADS)

    Raoelison, R. N.; Sapanathan, T.; Padayodi, E.; Buiron, N.; Rachik, M.

    2016-11-01

    This paper investigates the complex interfacial kinematics and governing mechanisms during high speed impact conditions. A robust numerical modelling technique using Eulerian simulations are used to explain the material response of the interface subjected to a high strain rate collision during a magnetic pulse welding. The capability of this model is demonstrated using the predictions of interfacial kinematics and revealing the governing mechanical behaviours. Numerical predictions of wave formation resulted with the upward or downward jetting and complex interfacial mixing governed by wake and vortex instabilities corroborate the experimental observations. Moreover, the prediction of the material ejection during the simulation explains the experimentally observed deposited particles outside the welded region. Formations of internal cavities along the interface is also closely resemble the resulted confined heating at the vicinity of the interface appeared from those wake and vortex instabilities. These results are key features of this simulation that also explains the potential mechanisms in the defects formation at the interface. These results indicate that the Eulerian computation not only has the advantage of predicting the governing mechanisms, but also it offers a non-destructive approach to identify the interfacial defects in an impact welded joint.

  1. Walleye Sander vitreus (Mitchill) are relatively resistant to experimental infection with VHSV IVb and extant walleye strains vary in susceptibility.

    PubMed

    Grice, J; Reid, A; Peterson, A; Blackburn, K; Tubbs, L; Lord, S; Huber, P; Horricks, R; Dixon, B; Bols, N C; Lumsden, J S

    2014-09-15

    Compared to fathead minnow, walleye demonstrate low susceptibility to experimental infection with VHSV IVb, regardless of route of exposure or water temperature at time of infection. In triplicate and duplicate groups, walleye were intraperitoneally (i.p.) injected (10(2) -10(8)  pfu/fish) or waterborne-exposed (w; 1.4 × 10(7)  pfu mL(-1) ) with VHSV IVb. High cumulative mortality (64-100%) and severe gross lesions associated with VHSV IVb infection were evident only in fish i.p. injected with 10(8)  pfu at 12 °C. These fish had multifocal necrosis of several tissues including the gill and heart. There was no difference in mortality between walleye infected (w or i.p.) at 12 °C (spring stocking) compared with a declining temperature profile from 18 to 12 °C (fall stocking). There were significant differences (P < 0.05) in mortality between four extant walleye strains following i.p. infection, indicating that the choice of walleye strain for stocking might be an important consideration. Viral antigen was found in both i.p. and w-exposed walleye using immunohistochemistry, mostly within the gill and skin of w-exposed fish and most prominently in dermal fibrocytes. VHSV IVb was detected in multiple tissues from 6 to 21 days post-infection using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR).

  2. Experimental and first-principles study of the electronic transport properties of strained Bi2Te3 thin films on a flexible substrate

    NASA Astrophysics Data System (ADS)

    Inamoto, Takuya; Takashiri, Masayuki

    2016-09-01

    On the basis of an experimental and first-principles study, strain effects on the thermoelectric properties of bismuth telluride (Bi2Te3) thin films were investigated. Bi2Te3 thin films were deposited on flexible polyimide substrates using a radio frequency magnetron sputtering method at a substrate temperature of 200 °C. Prior to deposition, various compressive and tensile bending strains were applied to the films by changing the bending radii of the flexible substrates. The structural and thermoelectric properties of the completed samples were analyzed. It was found that the lattice parameters of all samples exhibited smaller values compared to that of standard data for Bi2Te3 (JCPDS 15-0863) because the substrates might have shrunk during the film deposition, indicated by the fact that all the samples presented various compressive lattice strains. A theoretical analysis was performed using the first-principles study based on density functional theory. We calculated the electronic band structures for Bi2Te3 with the different lattice strains and predicted the thermoelectric properties based on the semi-classical Boltzmann transport equation in the rigid band approximation. The lowest conduction band edge in the Bi2Te3 band structure narrowed as the compressive lattice strain increased, indicating that the effective mass became smaller. Finally, the experimentally measured thermoelectric properties were compared with those obtained by the calculation. It was found that the calculated results were in good agreement with the experimental results.

  3. Experimental and Computational Study of the Shearing Resistance of Polyurea at High Pressures and High Strain Rates

    NASA Astrophysics Data System (ADS)

    Grujicic, Mica; Yavari, R.; Snipes, J. S.; Ramaswami, S.; Jiao, T.; Clifton, R. J.

    2015-02-01

    Mechanical response of polyurea, a nanophase segregated elastomeric co-polymer, is investigated using all-atom, equilibrium, molecular-dynamics methods and tools. Specifically, the effects of high pressure (1-30 GPa) and high strain rate (105-106 s-1) on the shearing resistance of polyurea are examined. Such loading conditions are encountered by polyurea coatings subjected to impact by high-velocity projectiles, shell shrapnel, and improvised explosive device fragments. Computed results are compared with their experimental counterparts obtained using the so-called pressure-shear plate impact experiments. Computed results have also been rationalized in terms of the nanosegregated polyurea microstructure consisting of rod-shaped, discrete, the so-called hard domains embedded in a highly compliant, the so-called soft matrix. By analyzing molecular-level microstructure and its evolution during high-rate deformation and under high imposed pressures, an attempt is made to identify and quantify main phenomena in viscous/inelastic deformation and microstructure-reorganization processes that are most likely responsible for the observed mechanical response of polyurea.

  4. An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain

    PubMed Central

    Cabrera-Covarrubias, Francisca Guadalupe; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Arredondo-Rea, Susana Paola; Gómez-Soberón, María Consolación; Corral-Higuera, Ramón

    2016-01-01

    The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications. PMID:28774151

  5. An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain.

    PubMed

    Cabrera-Covarrubias, Francisca Guadalupe; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Arredondo-Rea, Susana Paola; Gómez-Soberón, María Consolación; Corral-Higuera, Ramón

    2016-12-21

    The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications.

  6. Experimental Study on the Effect of freeze-thaw cycle on Silty Clay Stress-Strain Behaviour

    NASA Astrophysics Data System (ADS)

    Chen, Rong; Xue, Nan; Hao, Dong-xue; Gao, Yu-cong

    2017-06-01

    The area of seasonally frozen soil in China accounts for about 54% of the national territorial area. The property of seasonally frozen soil has a great influence on highway, railway and architectural foundation. The effect of freeze-thaw cycle for saturated silty clay in Northeast Area on stress-strain behaviour was investigated by triaxial test in this paper, where three different freezing temperature and five different freeze-thaw cycle times were considered. The results showed that silty clay exhibited strain softening characteristics for small number of freeze-thaw cycles, while strain hardening characteristics will appear with the increase in freeze-thaw cycles. The deviatoric stress-axial strain relationship shows the transitional form from strain softening to strain hardening. It will be helpful to understand the strain behaviour of soil under freeze-thaw cycle.

  7. Optimization of Magnetosome Production and Growth by the Magnetotactic Vibrio Magnetovibrio blakemorei Strain MV-1 through a Statistics-Based Experimental Design

    PubMed Central

    Silva, Karen T.; Leão, Pedro E.; Abreu, Fernanda; López, Jimmy A.; Gutarra, Melissa L.; Farina, Marcos; Bazylinski, Dennis A.; Freire, Denise M. G.

    2013-01-01

    The growth and magnetosome production of the marine magnetotactic vibrio Magnetovibrio blakemorei strain MV-1 were optimized through a statistics-based experimental factorial design. In the optimized growth medium, maximum magnetite yields of 64.3 mg/liter in batch cultures and 26 mg/liter in a bioreactor were obtained. PMID:23396329

  8. Experimental high strain-rate deformation products of carbonate-silicate rocks: Comparison with terrestrial impact materials

    NASA Astrophysics Data System (ADS)

    van der Bogert, C. H.; Schultz, P. H.; Spray, J. G.

    2008-09-01

    MgO with CO2. However, both CaO and MgO were also incorporated into secondary silicates, which reduced the total amount available to back-react with CO2. It appears that all CaO released from the dolomitic marble formed secondary minerals (carbonates and silicates), because it is not present as pure CaO. The MgO released from the dolomitic marble primarily formed secondary silicates, periclase, and minor secondary carbonate. As a result, the secondary carbonates cannot be a sink for all the CO2 gas released from the dolomitic marble, unless a much higher proportion of the huntite-like phase was present. Thus, there was a net release of CO2 gas from the original dolomitic marble. A portion of this CO2 remained trapped in vesicles, but CO2 gas also escaped from the shear zone. This is consistent with compositional measurements of the shear zone that suggest a release of at least 5 wt% CO2 relative to the original dolomitic marble. Comparison with terrestrial craters. Many of the descriptions of deformation features in carbonates at terrestrial craters, such as mechanical twinning and bent fractures [9-11], are similar to those seen in our experimental products. Carbonates that survive impact seem to accommodate both shock and shear deformation primarily through mechanical fracturing and twinning. Impact melts at craters in carbonate-rich targets have been found to contain both silicic and carbonatitic melts [e.g., 12], with mineral phases that are indicative of high temperature reactions between carbonate and silicate rocks [e.g., 9]. Our experiments also showed these characteristics, however, the mineral phases produced were slightly different and we have not observed silicate glass in our experimental products. The segregation of MgO from CaO has been observed, for example, at Haughton [12] and Popigai [13], and was also seen in our experimental products [6]. Implications. The products of high strain-rate deformation experiments with carbonate-silicate rocks are

  9. Effect of Kaiyu Qingwei Jianji on the morphometry and residual strain distribution of small intestine in experimental diabetic rats

    PubMed Central

    Sha, Hong; Zhao, Jing-Bo; Zhang, Zhi-Yuan; Zhou, Shui-Ping; Tong, Xiao-Lin; Zhuang, Feng-Yuan; Gregersen, Hans

    2006-01-01

    AIM: To investigate the effect of a Chinese medicine, Kaiyu Qingwei Jianji (KYQWJJ) used for diabetic treatment, on the morphometry and residual strain distribution of the small intestine in streptozotocin (STZ) -induced diabetic rats. Correlation analysis was also performed between the opening angle and residual strain with the blood glucose level. METHODS: Forty-two male Wistar rats weighing 220-240 g were included in this study. Thirty-two STZ-induced diabetic rats were subdivided into four groups (n = 8 in each group), i.e. diabetic control group (DM); high dose of KYQWJJ (T1, 36g/kg per day); low dose of KYQWJJ (T2, 17 g/kg per day) and Gliclazide (T3, 50 mg/kg per day). Another ten rats were used as non-diabetic control (CON). The medicines were poured directly into stomach lumen by gastric lavage twice daily. The rats of CON and DM groups were only poured the physiological saline. Blood glucose and plasma insulin levels were measured. Experimental period was 35 d. At the end of experiment, three 5-cm long segments were harvested from the duodenum, jejunum and ileum. Three rings of 1-2 mm in length for no-load and zero-stress state tests were cut from the middle of different segments. The morphometric data, such as the circumferential length, the wall thickness and the opening angle were measured from the digitized images of intestinal segments in the no-load state and zero-stress state. The residual strain was computed from the morphometry data. Furthermore, the linear regression analysis was performed between blood glucose level with morphometric and biomechanical data in the different intestinal segments. RESULTS: The blood glucose level of DM group was consistent 4-fold to 5-fold higher than those in CON group during the experiment (16.89 ± 1.11 vs 3.44 ± 0.15 mmol/L, P < 0.001). The blood glucose level in the T1 (16.89 ± 1.11 vs 11.08 ± 2.67 mmol/L, P < 0.01) and T3 groups (16.89 ± 1.11 vs 13.54 ± 1.73 mmol/L, P < 0.05), but not in T2 group (P > 0

  10. Coherency strain and its effect on ionic conductivity and diffusion in solid electrolytes--an improved model for nanocrystalline thin films and a review of experimental data.

    PubMed

    Korte, C; Keppner, J; Peters, A; Schichtel, N; Aydin, H; Janek, J

    2014-11-28

    A phenomenological and analytical model for the influence of strain effects on atomic transport in columnar thin films is presented. A model system consisting of two types of crystalline thin films with coherent interfaces is assumed. Biaxial mechanical strain ε0 is caused by lattice misfit of the two phases. The conjoined films consist of columnar crystallites with a small diameter l. Strain relaxation by local elastic deformation, parallel to the hetero-interface, is possible along the columnar grain boundaries. The spatial extent δ0 of the strained hetero-interface regions can be calculated, assuming an exponential decay of the deformation-forces. The effect of the strain field on the local ionic transport in a thin film is then calculated by using the thermodynamic relation between (isostatic) pressure and free activation enthalpy ΔG(#). An expression describing the total ionic transport relative to bulk transport of a thin film or a multilayer as a function of the layer thickness is obtained as an integral average over strained and unstrained regions. The expression depends only on known material constants such as Young modulus Y, Poisson ratio ν and activation volume ΔV(#), which can be combined as dimensionless parameters. The model is successfully used to describe own experimental data from conductivity and diffusion studies. In the second part of the paper a comprehensive literature overview of experimental studies on (fast) ion transport in thin films and multilayers along solid-solid hetero-interfaces is presented. By comparing and reviewing the data the observed interface effects can be classified into three groups: (i) transport along interfaces between extrinsic ionic conductors (and insulator), (ii) transport along an open surface of an extrinsic ionic conductor and (iii) transport along interfaces between intrinsic ionic conductors. The observed effects in these groups differ by about five orders of magnitude in a very consistent way. The

  11. Experimental infection of specific pathogen-free New Zealand White rabbits with five strains of amyxomatous myxoma virus.

    PubMed

    Marlier, D; Cassart, D; Boucraut-Baralon, C; Coignoul, F; Vindevogel, H

    1999-11-01

    Myxomatosis is a specific disease of the European rabbit (Oryctolagus cuniculus) due to a virus belonging to the genus Leporipoxvirus. Forty-seven years after its deliberate introduction into Europe, the clinical aspects and the epizootiology of myxomatosis have changed. Two forms (nodular and amyxomatous) of the disease have been identified to date. A comparative study was made of the clinical signs, pathogenesis and gross lesions observed in male specific pathogen-free New Zealand White rabbits inoculated with five strains of amyxomatous myxoma virus. All five strains induced the characteristic amyxomatous myxomatosis clinical syndrome with clinical signs that differed only in intensity. The varying clinical intensity, together with the results of virological examination question the virulence of at least three of the five strains. Genomic analysis confirmed that the five strains came from the Lausanne strain introduced in 1952 in France and not from an unnoticed introduction of a Californian strain of myxoma virus. No link was found between the amyxomatous myxoma virus strains and the SG33 vaccine strain. 1999 Harcourt Publishers Ltd.

  12. Virulence attenuation of a Mycobacterium avium subspecies paratuberculosis S-type strain prepared from intestinal mucosa after bacterial culture. Evaluation in an experimental ovine model.

    PubMed

    Fernández, Miguel; Delgado, Laetitia; Sevilla, Iker A; Fuertes, Miguel; Castaño, Pablo; Royo, Marcos; Ferreras, M Carmen; Benavides, Julio; Pérez, Valentín

    2015-04-01

    The differences in pathogenicity between an inoculum derived directly from an intestinal tissue homogenate from a paratuberculosis affected sheep and the S-type Mycobacterium avium subsp. partuberculosis (Map) strain isolated in laboratory media from the mentioned homogenate were assessed in two experiments in lambs. Specific peripheral immune responses were significantly lower in animals inoculated with the cultured organisms that showed only granulomatous lesions in the intestinal lymphoid tissue. However, in the homogenate group, more abundant granulomata also occurred in the lamina propria. Map was isolated only in lambs infected with the culture strain. Map DNA was demonstrated by nested-PCR in all the lambs but in a lower proportion (57.1% vs 100%) in those from the culture group. Under these particular experimental conditions, the results suggest that an attenuation of Map virulence has occurred in the cultured strain compared to the initial tissue homogenate, even after a low number of passages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Enterococcus faecium strain L-3 and glatiramer acetate ameliorate experimental allergic encephalomyelitis in rats by affecting different populations of immune cells.

    PubMed

    Abdurasulova, I N; Matsulevich, A V; Tarasova, E A; Kudryavtsev, I V; Serebrjakova, M K; Ermolenko, E I; Bisaga, G N; Klimenko, V M; Suvorov, A N

    2016-11-30

    The effect of probiotic Enterococcus faecium strain L-3 was studied in rats with experimental allergic encephalomyelitis (EAE). Glatiramer acetate (GA) was used as control drug. E. faecium strain L-3 and GA both were able to reduce the severity of EAE in a similar fashion. Both approaches increased the proportion of EAE resistant rats and rats with mild disease, prolonged the inductive phase of EAE and reduced the disease duration. Study of the phenotypes of immune cells in blood revealed the differences in immunoregulatory pathways that mediate the protective action of probiotic or GA treatment of EAE. The presence of pronounced protective and immunomodulating effects of the probiotic E. faecium strain L-3 opens an opportunity of its application for the treatment of multiple sclerosis.

  14. Comparison of the immune responses associated with experimental bovine mastitis caused by different strains of Escherichia coli.

    PubMed

    Blum, Shlomo E; Heller, Elimelech D; Jacoby, Shamay; Krifucks, Oleg; Leitner, Gabriel

    2017-05-01

    We studied the mammary immune response to different mammary pathogenic Escherichia coli (MPEC) strains in cows, hypothesising that the dynamics of response would differ. E. coli is a major aetiologic agent of acute clinical bovine mastitis of various degrees of severity with specific strains being associated with persistent infections. We compared challenge with three distinct pathogenic MPEC strains (VL2874, VL2732 and P4), isolated from different forms of mastitis (per-acute, persistent and acute, respectively). A secondary objective was to verify the lack of mammary pathogenicity of an environmental isolate (K71) that is used for comparison against MPEC in genomic and phenotypic studies. Twelve cows were challenged by intra-mammary infusion with one of the strains. Cellular and chemokine responses and bacterial culture follow-up were performed for 35 d. All cows challenged by any of the MPEC strains developed clinical mastitis. Differences were found in the intensity and duration of response, in somatic cell count, secreted cytokines (TNF-α, IL-6 and IL-17) and levels of milk leucocyte membrane Toll-like receptor 4 (TLR4). A sharp decrease of TLR4 on leucocytes was observed concomitantly to peak bacterial counts in milk. Intra-mammary infusion of strain K71 did not elicit inflammation and bacteria were not recovered from milk. Results suggest some differences in the mammary immune response to distinct MPEC strains that could be correlated to their previously observed pathogenic traits. This is also the first report of an E. coli strain that is non-pathogenic to the bovine mammary gland.

  15. Experimental Determination of the Surface Displacement of a Small Flexural Disk Sonar Transducer From Surface Strain Measurements

    DTIC Science & Technology

    1993-06-01

    frequency sources has stimulated the research and development of large arrays of flexural mode (" flextensional ") transducers . the development of such...OF A SMALL FLEXURAL DISK SONAR TRANSDUCER FROM SURFACE STRAIN MEASUREMENTS by Douglas L. Cuthbert June 1993 Thesis Advisor: S.R. Baker Approved for...Of The Surface Displacement Of A Small Flexural Disk Sonar Transducer From Surface Strain Measurements by Douglas Lee Cuthbert Lieutenant, United

  16. Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

    DOE PAGES

    Coriton, Bruno; Frank, Jonathan H.

    2016-02-16

    In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet withmore » Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal to s3¯.« less

  17. Experimental and computational investigation of the response of an elastomer at pressures up to 18 GPa and strain rates of 105 -106 s-1

    NASA Astrophysics Data System (ADS)

    Jiao, T.; Clifton, Rodney J.

    2017-01-01

    Pressure-shear plate impact (PSPI) experiments have been conducted to study the mechanical response of an elastomer (polyurea) at high pressures and high strain rate. The previously determined isentrope has been extended to 18 GPa. At this pressure, the high-strain-rate shearing resistance of polyurea is approximately 1 GPa. From the PSPI tests, it is evident that the shearing resistance of polyurea is quite sensitive to pressure. Based on the experimental results, a quasilinear viscoelasticity model is introduced and implemented in ABAQUS to simulate the response of polyurea P1000 under the impact conditions of the various PSPI experiments. Results of these simulations are compared with the experimental results to gain insight into the viability of the proposed model.

  18. [Biological features and experimental pathogenicity of Candida strains isolated by hemoculture at the Hospital Infantil de México "Federico Gómez"].

    PubMed

    Ramírez Aguilar, M L; Pérez Miravete, A; Santos Preciado, J I

    1992-01-01

    In a period of 15 months (1990-1991) it was carried out 5781 blood cultures in which 180 strains of yeast-like were isolated. 116 of these strains were selected for biochemical classification, cellular and colonial morphology and experimental determination of virulence in mice. Most of the strains were classified as Candida albicans (60%) and the others were C. tropicalis (15.5%); C. guillermondii (10.3%); T. glabrata (6.8%); Rhodotorula rubra (3.4%); Cryptococcus neoformans (2.58%) y C. parapsilosis (0.86%). C. albicans ATCC14053, y C. tropicalis ATCC14056 and T. glabrata ATCC15545 were employed as controls. The virulence test was performed using mice of 20-30 gr (4-6 weeks age) by intravenous injection in caudal vein with 0.5 ml of different suspension from 10(5) to 10(9) CFU/ml. Observation time was 10 days. Target organ was kidney by macro and microscopic observation of micro-abscess death. LD50 was estimated by the Reed-muench method. Intraspecific and interspecific differences were observed. It is more valid if we take into account that the experiment was done in homogenous population of host without risk factor which influences the human population in hospitals. Experimental virulence was compared with the evolution of diseases in the human host of which the strain was isolated.

  19. Immune Response Induced by an Immunodominant 60 kDa Glycoprotein of the Cell Wall of Sporothrix schenckii in Two Mice Strains with Experimental Sporotrichosis

    PubMed Central

    Alba-Fierro, Carlos A.; Pérez-Torres, Armando; Toriello, Conchita; Pulido-Camarillo, Evelyn; Romo-Lozano, Yolanda; Gutiérrez-Sánchez, Gerardo

    2016-01-01

    Cell wall (CW) components of fungus Sporothrix schenckii are the major inductors antigens of immune responses. The immunodominant 60 kDa glycoprotein (gp60) has been shown to be associated with the virulence of this fungus but its role in experimental sporotrichosis is unknown. In this work, the immunological effects of CW-purified gp60 were investigated in a model of experimental subcutaneous sporotrichosis in normal and gp60-preimmunized C57BL/6 and BALB/c mice strains which were then infected with S. schenckii conidia. Results showed that both mice strains use different cytokine profiles in order to fight S. schenckii infection; C57BL/6 mice seem to use a Th17 response while BALB/c mice tend to depend on a Th1 profile. Preimmunization with gp60 showed a downregulatory effect on the immune response since cytokines levels were diminished in both strains. There were no significant differences in the magnitude of dorsoplantar inflammation between gp60-preimmunized and nonimmunized mice of both strains. However, skin lesions due to the infection in gp60-preimmunized mice were more severe in BALB/c than in C57BL/6 mice, suggesting that the antigen exerts a higher downregulatory effect on the Th1 response. PMID:27051673

  20. Immune Response Induced by an Immunodominant 60 kDa Glycoprotein of the Cell Wall of Sporothrix schenckii in Two Mice Strains with Experimental Sporotrichosis.

    PubMed

    Alba-Fierro, Carlos A; Pérez-Torres, Armando; Toriello, Conchita; Pulido-Camarillo, Evelyn; López-Romero, Everardo; Romo-Lozano, Yolanda; Gutiérrez-Sánchez, Gerardo; Ruiz-Baca, Estela

    2016-01-01

    Cell wall (CW) components of fungus Sporothrix schenckii are the major inductors antigens of immune responses. The immunodominant 60 kDa glycoprotein (gp60) has been shown to be associated with the virulence of this fungus but its role in experimental sporotrichosis is unknown. In this work, the immunological effects of CW-purified gp60 were investigated in a model of experimental subcutaneous sporotrichosis in normal and gp60-preimmunized C57BL/6 and BALB/c mice strains which were then infected with S. schenckii conidia. Results showed that both mice strains use different cytokine profiles in order to fight S. schenckii infection; C57BL/6 mice seem to use a Th17 response while BALB/c mice tend to depend on a Th1 profile. Preimmunization with gp60 showed a downregulatory effect on the immune response since cytokines levels were diminished in both strains. There were no significant differences in the magnitude of dorsoplantar inflammation between gp60-preimmunized and nonimmunized mice of both strains. However, skin lesions due to the infection in gp60-preimmunized mice were more severe in BALB/c than in C57BL/6 mice, suggesting that the antigen exerts a higher downregulatory effect on the Th1 response.

  1. Lethal Experimental Tick-Borne Encephalitis Infection: Influence of Two Strains with Similar Virulence on the Immune Response

    PubMed Central

    Shevtsova, Anastasia S.; Motuzova, Oxana V.; Kuragina, Vera M.; Akhmatova, Nelli K.; Gmyl, Larissa V.; Kondrat'eva, Yaroslava I.; Kozlovskaya, Liubov I.; Rogova, Yulia V.; Litov, Alexander G.; Romanova, Lidiya Iu.; Karganova, Galina G.

    2017-01-01

    Tick-borne encephalitis virus (TBEV) is a tick-transmitted arbovirus that causes serious diseases in humans in Europe and Northern Asia. About 6000–10,000 cases are registered annually, and one-third of them lead to sequela with different degrees of severity. Two TBEV strains (Absettarov and EK-328) similar in virulence rate in laboratory mice were used to study pathogenesis and immune response upon lethal infection in mice. The strains differed in the dynamics of appearance of virus, IFNs and other cytokines in blood of mice, and ability to induce a cytokine storm in the terminal stages of disease and a non-sterile immunity. Moreover, the TBEV strains differed in characteristics of their interactions with DCs: level of reproduction in these cells, virus dose triggering IFN-α production, and impact on DCs' maturation. Infection of DCs with Absettarov strain led to IFN-α induction only at high multiplicity of infection (MOI), and an increased amount of the mature DCs with high adhesion activity and low-level of MHCII positive cells. While reproduction of the EK-328 strain in DCs was less efficient, a low dose of the virus induced IFN-α production and stimulated maturation of DCs with relatively low adhesive capacity, but with the high percentage of cells expressing MHCII molecules. Thus, the studied strains differed significantly in the impact on DCs' maturation and antigen presentation to CD4+ lymphocytes. Injection of low (103 PFU) and high (106 PFU) doses of both TBEV strains caused a lethal infection in mice. At the same time, the dose of the virus in the inoculum, regardless of the strain properties, affected the following virulence characteristics: the time of virus appearance in brain (day 4–5 vs. day 1 p.i.), time of IFN-α appearance in blood (10 h vs. 5 h p.i.), concentration of IFN-α in blood, and induction of IFN-α during infection of DCs. Therefore, virulent TBEV strains during lethal infection can interact differently with the host immune

  2. An experimental investigation of strain rate, temperature and humidity effects on the mechanical behavior of a perfluorosulfonic acid membrane

    NASA Astrophysics Data System (ADS)

    Lu, Zongwen; Lugo, Melissa; Santare, Michael H.; Karlsson, Anette M.; Busby, F. Colin; Walsh, Peter

    2012-09-01

    The time-dependent hygro-thermal mechanical behavior of a perfluorosulfonic acid (PFSA) membrane (Nafion® 211 membrane) commonly used in Proton Exchange Membrane Fuel Cells (PEMFCs) is investigated at selected strain rates for a broad range of temperatures and humidities. Tensile tests and relaxation tests are conducted to determine Young's modulus and proportional limit stress as functions of strain rate, temperature and humidity. The results show that Young's modulus and proportional limit stress increase as the strain rate increases, and decrease as the temperature or humidity increases. The results also show that the mechanical response of Nafion® 211 membrane is more sensitive to typical changes in strain rate or temperature than to typical changes in humidity. In addition, two temperature/humidity cycles are conducted to determine the steady state swelling behavior of Nafion® 211 membrane as a function of temperature and humidity. The results show that the membrane swells with increasing temperature and humidity, and that there is little or no hygro-thermal history effect for the swelling strains.

  3. Susceptibility to Experimental Cerebral Malaria Induced by Plasmodium berghei ANKA in Inbred Mouse Strains Recently Derived from Wild Stock

    PubMed Central

    Bagot, S.; Idrissa Boubou, M.; Campino, S.; Behrschmidt, C.; Gorgette, O.; Guénet, J.-L.; Penha-Gonçalves, C.; Mazier, D.; Pied, S.; Cazenave, P.-A.

    2002-01-01

    The neurological syndrome caused by Plasmodium berghei ANKA in rodents partially mimics the human disease. Several rodent models of cerebral malaria (CM) exist for the study of the mechanisms that cause the disease. However, since common laboratory mouse strains have limited gene pools, the role of their phenotypic variations causing CM is restricted. This constitutes an obstacle for efficient genetic analysis relating to the pathogenesis of malaria. Most common laboratory mouse strains are susceptible to CM, and the same major histocompatibility complex (MHC) haplotype may exhibit different levels of susceptibility. We analyzed the influence of the MHC haplotype on overcoming CM by using MHC congenic mice with C57BL/10 and C3H backgrounds. No correlation was found between MHC molecules and the development of CM. New wild-derived mouse strains with wide genetic polymorphisms were then used to find new models of resistance to CM. Six of the twelve strains tested were resistant to CM. For two of them, F1 progeny and backcrosses performed with the reference strain C57BL/6 showed a high level of heterogeneity in the number and characteristics of the genetic factors associated with resistance to CM. PMID:11895970

  4. Ductile failure of steel HY80 under high strain rates and triaxial stress states, experimental results and damage description

    NASA Astrophysics Data System (ADS)

    Abdel-Malek, S.; Halle, Th.; Meyer, L. W.

    2003-09-01

    Ductile fracture investigations are an important part in current research. The simulation of fracture by means of numerical codes needs precise material data that may be reached from accurate mechanical testing. In order to predict failure processes, the stress state history as a function of strain development has to be known. In this work tensile tests on HY80 steel were performed under quasistatic and high strain rate loading conditions at room temperature using smooth and notched specimens. The force-time and displacement-time behaviour was measured during testing. Additionally, scanning electron microscopy was used to investigate the fractured surfaces. Furthermore, different models were applied to describe the failure process. FE-calculations were used to receive the stress state in the material in the region of the notch as a function of strain development.

  5. Experimental infection and comparative genomic analysis of a highly pathogenic PRRSV-HBR strain at different passage levels.

    PubMed

    Wei, Yanwu; Li, Shengbin; Huang, Liping; Tang, Qinghai; Liu, Jianbo; Liu, Dan; Wang, Yiping; Wu, Hongli; Liu, Changming

    2013-10-25

    A highly pathogenic strain of porcine reproductive and respiratory syndrome virus (PRRSV-HBR) was passaged on Marc-145 cells for 125 passages. In order to elucidate the change in virulence of PRRSV-HBR strain during the process of passage in vitro, swine infection experiment was performed with the viruses of low (F5 and F10) and high passage (F125). In addition, to identify the mutations related to the change in virulence of PRRSV-HBR strain, we compared and analyzed the genomic sequences of the F5, F10 and F125 of the strain. The virulence of F125 was significantly lower than that of F5 in the virus-infected pigs. In comparison with F5 and F125, there were 45 amino acids (aa) mutations and a deletion of 2 continuous aa by means of the virus genome sequence analysis. For these mutations, 33 aa (73.3%) occurred in the viral nonstructural proteins and the other 12 aa (26.7%) were contained in the viral structural proteins. Of the mutations, only 15 aa (33.3%) appeared in F10 and 30 aa (66.7%) occurred during passage from F10 to F125. The data showed that the latter 30 aa mutations were probably associated with attenuation of PRRSV-HBR strain, and that the change in virulence of the virus was determined by multiple alterations both in the structural and nonstructural genes. The virulence of PRRSV-HBR strain was remarkably attenuated after serial passages, and it can be used as vaccine candidate for control of the PRRS.

  6. Experimental Study of Anisotropic Stress/Strain Relationships of Aortic and Pulmonary Artery Homografts and Synthetic Vascular Grafts.

    PubMed

    Jia, Yueqian; Qiao, Yangyang; Ricardo Argueta-Morales, I; Maung, Aung; Norfleet, Jack; Bai, Yuanli; Divo, Eduardo; Kassab, Alain J; DeCampli, William M

    2017-10-01

    Homografts and synthetic grafts are used in surgery for congenital heart disease (CHD). Determining these materials' mechanical properties will aid in understanding tissue behavior when subjected to abnormal CHD hemodynamics. Homograft tissue samples from anterior/posterior aspects, of ascending/descending aorta (AA, DA), innominate artery (IA), left subclavian artery (LScA), left common carotid artery (LCCA), main/left/right pulmonary artery (MPA, LPA, RPA), and synthetic vascular grafts, were obtained in three orientations: circumferential, diagonal (45 deg relative to circumferential direction), and longitudinal. Samples were subjected to uniaxial tensile testing (UTT). True strain-Cauchy stress curves were individually fitted for each orientation to calibrate Fung model. Then, they were used to calibrate anisotropic Holzapfel-Gasser model (R2 > 0.95). Most samples demonstrated a nonlinear hyperelastic strain-stress response to UTT. Stiffness (measured by tangent modulus at different strains) in all orientations were compared and shown as contour plots. For each vessel segment at all strain levels, stiffness was not significantly different among aspects and orientations. For synthetic grafts, stiffness was significantly different among orientations (p < 0.042). Aorta is significantly stiffer than pulmonary artery at 10% strain, comparing all orientations, aspects, and regions (p = 0.0001). Synthetic grafts are significantly stiffer than aortic and pulmonary homografts at all strain levels (p < 0.046). Aortic, pulmonary artery, and synthetic grafts exhibit hyperelastic biomechanical behavior with anisotropic effect. Differences in mechanical properties among vascular grafts may affect native tissue behavior and ventricular/arterial mechanical coupling, and increase the risk of deformation due to abnormal CHD hemodynamics.

  7. Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

    SciTech Connect

    Coriton, Bruno; Frank, Jonathan H.

    2016-02-16

    In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet with Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal

  8. Efficacy of dart or booster vaccination with strain RB51 in protecting bison against experimental Brucella abortus challenge

    USDA-ARS?s Scientific Manuscript database

    Vaccination is an effective tool for reducing the prevalence of brucellosis in natural hosts. In this study, we characterized the efficacy of the Brucella abortus strain RB51 (RB51) vaccine in bison when delivered by single intramuscular vaccination (Hand RB51), single pneumatic dart delivery (Dart ...

  9. Pathogenicity of three type 2 Porcine Reproductive and Respiratory Syndrome virus strains in experimentally inoculated pregnant gilts

    USDA-ARS?s Scientific Manuscript database

    Mechanisms of reproductive failure resulting from infection with porcine reproductive and respiratory syndrome virus (PRRSv) are still poorly understood. The present study, a side-by-side evaluation of the pathogenicity of three type 2 PRRSv strains in a reproductive model, was used as a pilot study...

  10. Experimental insight into the proximate causes of male persistence variation among two strains of the androdioecious Caenorhabditis elegans (Nematoda)

    PubMed Central

    Wegewitz, Viktoria; Schulenburg, Hinrich; Streit, Adrian

    2008-01-01

    Background In the androdioecious nematode Caenorhabditis elegans virtually all progeny produced by hermaphrodite self-fertilization is hermaphrodite while 50% of the progeny that results from cross-fertilization by a male is male. In the standard laboratory wild type strain N2 males disappear rapidly from populations. This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856. Results We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences. We performed systematic inter- and intra-strain crosses with N2 and CB4856 and show that the males and the hermaphrodites contribute to the difference in male maintenance between these two strains. In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny. On the other hand, N2 hermaphrodites produced a higher number of self-progeny, both when singly mated and when not mated. Conclusion These two differences have the potential to explain the observed variation in male persistence, since they should lead to a predominance of self-progeny (and thus hermaphrodites) in N2 and, at the same time, a high proportion of cross-progeny (and thus the presence of males as well as hermaphrodites) in CB4856. PMID:18620600

  11. Theoretical and Experimental Study of Lower-Dimensional One-Dimensional and Zero-Dimensional Strained Quantum System.

    NASA Astrophysics Data System (ADS)

    Tan, I.-Hsing

    1992-01-01

    With the success of the optoelectronic devices based on the two-dimensional (2D) quantum well, it is a natural trend to continue to reduce system's dimensionality to 1D and 0D systems. However, extrinsic fabrication defects such as process-induced damage and pattern non-uniformity and intrinsic defects such as a slower hot carrier cooling rate can render the luminescence of the wires and dots extremely poor. In this dissertation, I will show that strain modulation and low-damage dry/wet etching techniques allow one to obtain high luminescence strain-induced quantum wires (SIQWs) and dots (SIQDs) with lateral dimensions less than 100 nm. The reduction of the fabrication-induced defects has allowed us to examine the intrinsic optical properties of the SIQWs and SIQDs through the photoluminescence (PL), PL excitation (PLE), and PL decay spectroscopy. Using epitaxial InGaAs layer as a stressor, we have achieved a ~20 meV of strain modulation and a ~7 meV of subband spacing in the SIQW structures having a lateral dimension of 75 nm and have observed an increase of FL decay time in the SIQD structures. The energy shifts, subband spacing, and increased PL decay time observed in the SIQWs and SIQDs can be well interpreted by our theoretical model, based on solving both the elasticity equation as well as the Luttinger-Kohn four-band Hamiltonian including strain.

  12. Transcriptome Profiling in Rat Inbred Strains and Experimental Cross Reveals Discrepant Genetic Architecture of Genome-Wide Gene Expression

    PubMed Central

    Kaisaki, Pamela J.; Otto, Georg W.; Argoud, Karène; Collins, Stephan C.; Wallis, Robert H.; Wilder, Steven P.; Yau, Anthony C. Y.; Hue, Christophe; Calderari, Sophie; Bihoreau, Marie-Thérèse; Cazier, Jean-Baptiste; Mott, Richard; Gauguier, Dominique

    2016-01-01

    To test the impact of genetic heterogeneity on cis- and trans-mediated mechanisms of gene expression regulation, we profiled the transcriptome of adipose tissue in 20 inbred congenic strains derived from diabetic Goto–Kakizaki (GK) rats and Brown–Norway (BN) controls, which contain well-defined blocks (1–183 Mb) of genetic polymorphisms, and in 123 genetically heterogeneous rats of an (GK × BN)F2 offspring. Within each congenic we identified 73–1351 differentially expressed genes (DEGs), only 7.7% of which mapped within the congenic blocks, and which may be regulated in cis. The remainder localized outside the blocks, and therefore must be regulated in trans. Most trans-regulated genes exhibited approximately twofold expression changes, consistent with monoallelic expression. Altered biological pathways were replicated between congenic strains sharing blocks of genetic polymorphisms, but polymorphisms at different loci also had redundant effects on transcription of common distant genes and pathways. We mapped 2735 expression quantitative trait loci (eQTL) in the F2 cross, including 26% predominantly cis-regulated genes, which validated DEGs in congenic strains. A hotspot of >300 eQTL in a 10 cM region of chromosome 1 was enriched in DEGs in a congenic strain. However, many DEGs among GK, BN and congenic strains did not replicate as eQTL in F2 hybrids, demonstrating distinct mechanisms of gene expression when alleles segregate in an outbred population or are fixed homozygous across the entire genome or in short genomic regions. Our analysis provides conceptual advances in our understanding of the complex architecture of genome expression and pathway regulation, and suggests a prominent impact of epistasis and monoallelic expression on gene transcription. PMID:27646706

  13. Cross-neutralization studies with salmonid alphavirus subtype 1-6 strains: results with sera from experimental studies and natural infections.

    PubMed

    Graham, D A; Rowley, H R; Frost, P

    2014-08-01

    The serological reactivity between strains of each of the six currently genetically defined subtypes of salmonid alphavirus (SAV) was examined by comparison of homologous and heterologous virus neutralization titres on sera from experimentally infected fish. With the exception of the level of SAV subtype 6 neutralization by heterologous sera, good cross-neutralization was detected between all subtypes, albeit with variation in geometric mean titres when each subtype-specific serum set was tested against the panel of virus subtypes. A similar pattern was evident with field sera, except that heterologous neutralization of the SAV6 strain was more evident. In only 23% of available pairwise comparisons was the homologous titre recorded with an experimentally derived serum fourfold or greater than the heterologous titre, and in only two instances was this difference demonstrated in both directions. No virus strains consistently met the old serology-based criteria (Sub-committee on Inter-relationships Among Catalogued Alphaviruses) to be considered separate subtypes within an alphavirus species. Only when testing with an SAV subtype-2-specific monoclonal antibody was a major difference between homologous and heterologous neutralization capacity evident. These results provide new direct or indirect information in terms of SAV classification, vaccine efficacy and the selection and validation of reagents for serological and immunological diagnostic purposes.

  14. [Efficacy of levofloxacin, lomefloxacin and moxifloxacin vs. other fluoroquinolones in experimental plague due to FI+ and FI- strains of Yersinia pestis in Albino mice].

    PubMed

    Ryzhko, I V; Tsuraeva, R I; Anisimov, B I; Trishina, A V

    2009-01-01

    Activity of levofloxacin, lomefloxacin and moxifloxacin against 20 FI+ and 20 FI- strains of Yersinia pestis was studied. It was shown that the strains were highly susceptible to the fluoroquinolones. In the experiments on mice subcutaneously infected with suspension of strains 231 FI+ and 231 FI- of Y. pestis in a dose of about 1000 LD50 (10(4) microbial cells) the ED50 of levofloxacin and moxifloxacin was 5.5-14.0 mg/kg independent of the infective culture phenotype and that of lomefloxacin was 18.5 mg/kg. Estimation of the impact of the pathogen infective dose value on the results of the experimental plague treatment with the therapeutic dose equivalent to the human one showed high efficacy of the fluoroquinolones (efficacy index of 10(4)). The treatment for 7 days provided 90-100-percent survival of the animals. The prophylactive use of lomefloxacin (in 5 hours - 5 days) was less efficient (70-80% of the survivals) in the animals infected with the antigen-changed (FI-) variant of the pathogen. Levofloxacin and moxifloxacin provided 90-100-percent survival of the animals treated for a course of 5 days independent of the pathogen phenotype. The study demonstrated that the use oflevofloxacin, lomefloxacin and moxifloxacin was prospective for the prophylaxis and therapy of experimental plague.

  15. Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach

    SciTech Connect

    I. M. Robertson; A. Beaudoin; J. Lambros

    2004-01-05

    OAK-135 Development and validation of constitutive models for polycrystalline materials subjected to high strain rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be closely coupled with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experimentation is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models, which will include dislocation-grain boundary interactions for polycrystalline systems. One aspect of the program will involve the dire ct

  16. Vaccination of Elk (Cervus canadensis) with Brucella abortus Strain RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes Does Not Induce Adequate Protection against Experimental Brucella abortus Challenge

    PubMed Central

    Nol, Pauline; Olsen, Steven C.; Rhyan, Jack C.; Sriranganathan, Nammalwar; McCollum, Matthew P.; Hennager, Steven G.; Pavuk, Alana A.; Sprino, Phillip J.; Boyle, Stephen M.; Berrier, Randall J.; Salman, Mo D.

    2016-01-01

    In recent years, elk (Cervus canadensis) have been implicated as the source of Brucella abortus infection for numerous cattle herds in the Greater Yellowstone Area. In the face of environmental and ecological changes on the landscape, the range of infected elk is expanding. Consequently, the development of effective disease management strategies for wild elk herds is of utmost importance, not only for the prevention of reintroduction of brucellosis to cattle, but also for the overall health of the Greater Yellowstone Area elk populations. In two studies, we evaluated the efficacy of B. abortus strain RB51 over-expressing superoxide dismutase and glycosyltransferase for protecting elk from infection and disease caused by B. abortus after experimental infection with a virulent B. abortus strain. Our data indicate that the recombinant vaccine does not protect elk against brucellosis. Further, work is needed for development of an effective brucellosis vaccine for use in elk. PMID:26904509

  17. Vaccination of Elk (Cervus canadensis) with Brucella abortus Strain RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes Does Not Induce Adequate Protection against Experimental Brucella abortus Challenge.

    PubMed

    Nol, Pauline; Olsen, Steven C; Rhyan, Jack C; Sriranganathan, Nammalwar; McCollum, Matthew P; Hennager, Steven G; Pavuk, Alana A; Sprino, Phillip J; Boyle, Stephen M; Berrier, Randall J; Salman, Mo D

    2016-01-01

    In recent years, elk (Cervus canadensis) have been implicated as the source of Brucella abortus infection for numerous cattle herds in the Greater Yellowstone Area. In the face of environmental and ecological changes on the landscape, the range of infected elk is expanding. Consequently, the development of effective disease management strategies for wild elk herds is of utmost importance, not only for the prevention of reintroduction of brucellosis to cattle, but also for the overall health of the Greater Yellowstone Area elk populations. In two studies, we evaluated the efficacy of B. abortus strain RB51 over-expressing superoxide dismutase and glycosyltransferase for protecting elk from infection and disease caused by B. abortus after experimental infection with a virulent B. abortus strain. Our data indicate that the recombinant vaccine does not protect elk against brucellosis. Further, work is needed for development of an effective brucellosis vaccine for use in elk.

  18. Experimental and theoretical studies of the superposition of intergranular and macroscopic strains in Ni-based industrial alloys

    SciTech Connect

    Holden, T.M.; Tome, C.N.; Holt, R.A.

    1998-12-01

    Measurements of the strain response to applied stress in polycrystalline MONEL-400 by neutron diffraction are modeled with the elastoplastic self-consistent (EPSC) theory. The strains in the different crystallographic orientations of grains, which are generated i the tensile test experiments, are shown to be caused by the anisotropy of elastic and plastic deformation with respect to crystallographic orientation. On the basis of the description of the results in the theory, the origin of a number of anomalies of a general nature in measurements by high neutron and X-ray diffraction can be understood. The theory is used to calculate which crystallographic reflections are least sensitive to intergranular effects under uniaxial tension.

  19. Effects of nutritional supplementation with l-arginine on repair of injuries due to muscle strain: experimental study on rats☆

    PubMed Central

    Couto, Lauren Izabel Medeiros; Wuicik, William Luiz; Kuhn, Ivan; Capriotti, Juan Rodolfo Vilela; Repka, João Carlos

    2015-01-01

    Objective To evaluate the influence of oral supplementation with arginine on regeneration of injuries due to straining of the anterior tibial muscle of rats. Methods Twenty-four Wistar rats of weight 492.5 ± 50.45 g were used. Injuries were induced through straining the anterior tibial muscles. The rats were separated into three groups of eight rats each. In the untreated group (UTG), after induction of injuries, the rats were observed for 24 h. In the simulation group (SG) and the arginine group (AG) respectively, the rats received isotonic saline solution and arginine solution via direct gavage, over a seven-day period. At the end of the period, blood samples were collected for serum evaluations of creatine kinase (CK), lactic dehydrogenase (LDH), aspartate aminotransferase (AST) and C-reactive protein (CRP). The right and left anterior tibial muscles were resected for histopathological evaluations on the muscle injuries, investigating edema, hemorrhage and disorganization or morphometric alteration of the muscle fibers. The tissue repair was investigated in terms of proliferation of adipose tissue, angiogenesis and collagen fibers. The ANOVA and Student's t methods were used and p ≤ 0.05 was taken to be statistically significant. Results In the serum evaluations, the AG showed lower CK assay values and higher AST values. In the histopathological evaluation, the UTG presented edema and hemorrhage compatible with injuries due to strain; the SG presented edema and hemorrhage with proliferation of adipose tissue and collagen fibers; and the AG presented not only the findings of the SG but also, especially, intense angiogenesis. Conclusion Oral supplementation with arginine did not cause any significant metabolic alterations that would contraindicate its use and it induced angiogenesis during the repair of muscles injured due to strain. PMID:26401505

  20. Immunohistochemistry for detection of avian infectious bronchitis virus strain M41 in the proventriculus and nervous system of experimentally infected chicken embryos

    PubMed Central

    Abdel-Moneim, Ahmed S; Zlotowski, Priscila; Veits, Jutta; Keil, Günther M; Teifke, Jens P

    2009-01-01

    Background Infectious bronchitis virus primarily induces a disease of the respiratory system, different IBV strains may show variable tissue tropisms and also affect the oviduct and the kidneys. Proventriculitis was also associated with some new IBV strains. Aim of this study was to investigate by immunohistochemistry (IHC) the tissue tropism of avian infectious bronchitis virus (IBV) strain M41 in experimentally infected chicken embryos. Results To this end chicken embryos were inoculated in the allantoic sac with 103 EID50 of IBV M41 at 10 days of age. At 48, 72, and 120 h postinoculation (PI), embryos and chorioallantoic membranes (CAM) were sampled, fixed, and paraffin-wax embedded. Allantoic fluid was also collected and titrated in chicken embryo kidney cells (CEK). The sensitivity of IHC in detecting IBV antigens in the CAM of inoculated eggs matched the virus reisolation and detection in CEK. Using IHC, antigens of IBV were detected in nasal epithelium, trachea, lung, spleen, myocardial vasculature, liver, gastrointestinal tract, kidney, skin, sclera of the eye, spinal cord, as well as in brain neurons of the inoculated embryos. These results were consistent with virus isolation and denote the wide tissue tropism of IBV M41 in the chicken embryo. Most importantly, we found infection of vasculature and smooth muscle of the proventriculus which has not seen before with IBV strain M41. Conclusion IHC can be an additional useful tool for diagnosis of IBV infection in chickens and allows further studies to foster a deeper understanding of the pathogenesis of infections with IBV strains of different virulence. Moreover, these results underline that embryonic tissues in addition to CAM could be also used as possible source to generate IBV antigens for diagnostic purposes. PMID:19196466

  1. Protective effects of recombinant staphylococcal enterotoxin type C mutant vaccine against experimental bovine infection by a strain of Staphylococcus aureus isolated from subclinical mastitis in dairy cattle.

    PubMed

    Chang, Byoung Sun; Moon, Jin San; Kang, Hyun-Mi; Kim, Young-In; Lee, Hong-Kyun; Kim, Jong-Duk; Lee, Byung-Saeng; Koo, Hye Cheong; Park, Yong Ho

    2008-04-16

    Staphylococcus aureus is one of the main etiological agents of bovine mastitis; however, antibiotics that are effective against bovine strains of S. aureus are not currently available. Staphylococcal enterotoxin type C (SEC), a superantigen, is the enterotoxin most frequently expressed by bovine strains of S. aureus and one of immunogenic determinants. The purpose of this study was to evaluate the protective effectiveness of recombinant SEC mutant vaccine (MastaVactrade mark) against experimentally induced bovine infection. Three representative SEC secreting strains were selected from 9 candidate isolates that showed various intensities of pathogenicity on mice and inoculated into 5 lactating dairy cattle at a concentration of 50-5.0x10(8) CFU per quarter. The optimal experimental bovine subclinical mastitis model was produced by inoculation with 50 CFU of S. aureus 409 per quarter, a level which was not lethal to mice. After the experimental model was determined, other 3 cattle were intramuscularly administered three doses of vaccine at day 0, at 2 wks and at 6 wks. Nine quarters of 3 vaccinated cattle and 8 quarters of 3 control cattle were then challenged with S. aureus 409. An SEC-specific ELISA test conducted at 4 wks post-immunization confirmed the presence of a high antibody titer against SEC in all vaccinated cattle. The somatic cell counts from the vaccinated group remained relatively low, whereas those of control group increased significantly after challenge with S. aureus. After challenge, S. aureus was not isolated from any cattle in the vaccinated group, whereas it was isolated from 75% of the cattle in the control group. These results indicate that recombinant SEC mutant vaccine had a protective effect against S. aureus intramammary infection in lactating cattle.

  2. Experimental Challenge of Atlantic Cod (Gadus morhua) with a Brucella pinnipedialis Strain from Hooded Seal (Cystophora cristata)

    PubMed Central

    Nymo, Ingebjørg Helena; Seppola, Marit; Al Dahouk, Sascha; Bakkemo, Kathrine Ryvold; Jiménez de Bagüés, María Pilar; Godfroid, Jacques; Larsen, Anett Kristin

    2016-01-01

    Pathology has not been observed in true seals infected with Brucella pinnipedialis. A lack of intracellular survival and multiplication of B. pinnipedialis in hooded seal (Cystophora cristata) macrophages in vitro indicates a lack of chronic infection in hooded seals. Both epidemiology and bacteriological patterns in the hooded seal point to a transient infection of environmental origin, possibly through the food chain. To analyse the potential role of fish in the transmission of B. pinnipedialis, Atlantic cod (Gadus morhua) were injected intraperitoneally with 7.5 x 107 bacteria of a hooded seal field isolate. Samples of blood, liver, spleen, muscle, heart, head kidney, female gonads and feces were collected on days 1, 7, 14 and 28 post infection to assess the bacterial load, and to determine the expression of immune genes and the specific antibody response. Challenged fish showed an extended period of bacteremia through day 14 and viable bacteria were observed in all organs sampled, except muscle, until day 28. Neither gross lesions nor mortality were recorded. Anti-Brucella antibodies were detected from day 14 onwards and the expression of hepcidin, cathelicidin, interleukin (IL)-1β, IL-10, and interferon (IFN)-γ genes were significantly increased in spleen at day 1 and 28. Primary mononuclear cells isolated from head kidneys of Atlantic cod were exposed to B. pinnipedialis reference (NCTC 12890) and hooded seal (17a-1) strain. Both bacterial strains invaded mononuclear cells and survived intracellularly without any major reduction in bacterial counts for at least 48 hours. Our study shows that the B. pinnipedialis strain isolated from hooded seal survives in Atlantic cod, and suggests that Atlantic cod could play a role in the transmission of B. pinnipedialis to hooded seals in the wild. PMID:27415626

  3. Experimental infection of ectoparasitic arthropods with Rickettsia prowazekii (GvF-16 strain) and transmission to flying squirrels.

    PubMed

    Bozeman, F M; Sonenshine, D E; Williams, M S; Chadwick, D P; Lauer, D M; Elisberg, B L

    1981-01-01

    Epizootiologic studies conducted during the past few years showed the existence of widespread natural infection of the southern flying squirrel, Glaucomys volans, with epidemic typhus rickettsiae, Rickettsia prowazekii. The ecological findings strongly implicated transmission of the etiologic agent by an arthropod vector. Studies were conducted under controlled laboratory conditions to determine whether ectoparasites naturally associated with flying squirrels (squirrel fleas, lice, mites and ticks) were capable of acquiring, maintaining and transmitting the infection. Also studied were the cat flea, oriental rat flea and the human body louse. Flying squirrels inoculated with the GvF-16 strain of R. prowazekii circulated rickettsiae in their blood for 2-3 weeks, thus providing ample opportunity for arthropods feeding on them to become infected. The results with Dermacentor variabilis ticks indicated that the rickettsiae did not consistently survive in this insect and were not passed to the eggs of adult females that had been infected subcuticularly. Mites became infected by feeding on infectious blood but failed to sustain the infection. Also, mites fed on an infected flying squirrel did not transmit the infection to a normal squirrel. Squirrel, cat, and oriental rat fleas readily became infected by feeding on a rickettsemic host or on infectious blood through membranes, but failed to transmit the infection to susceptible flying squirrels. In the studies with flying squirrel lice, however, transmission of epidemic typhus from infected to uninfected flying squirrels was demonstrated. Infection of the human body louse with the GvF-16 flying squirrel strain of R. prowazekii was similar to that previously observed with classical human strains, viz., multiplication of the rickettsiae and excretion in the feces.

  4. Experimental Challenge of Atlantic Cod (Gadus morhua) with a Brucella pinnipedialis Strain from Hooded Seal (Cystophora cristata).

    PubMed

    Nymo, Ingebjørg Helena; Seppola, Marit; Al Dahouk, Sascha; Bakkemo, Kathrine Ryvold; Jiménez de Bagüés, María Pilar; Godfroid, Jacques; Larsen, Anett Kristin

    2016-01-01

    Pathology has not been observed in true seals infected with Brucella pinnipedialis. A lack of intracellular survival and multiplication of B. pinnipedialis in hooded seal (Cystophora cristata) macrophages in vitro indicates a lack of chronic infection in hooded seals. Both epidemiology and bacteriological patterns in the hooded seal point to a transient infection of environmental origin, possibly through the food chain. To analyse the potential role of fish in the transmission of B. pinnipedialis, Atlantic cod (Gadus morhua) were injected intraperitoneally with 7.5 x 107 bacteria of a hooded seal field isolate. Samples of blood, liver, spleen, muscle, heart, head kidney, female gonads and feces were collected on days 1, 7, 14 and 28 post infection to assess the bacterial load, and to determine the expression of immune genes and the specific antibody response. Challenged fish showed an extended period of bacteremia through day 14 and viable bacteria were observed in all organs sampled, except muscle, until day 28. Neither gross lesions nor mortality were recorded. Anti-Brucella antibodies were detected from day 14 onwards and the expression of hepcidin, cathelicidin, interleukin (IL)-1β, IL-10, and interferon (IFN)-γ genes were significantly increased in spleen at day 1 and 28. Primary mononuclear cells isolated from head kidneys of Atlantic cod were exposed to B. pinnipedialis reference (NCTC 12890) and hooded seal (17a-1) strain. Both bacterial strains invaded mononuclear cells and survived intracellularly without any major reduction in bacterial counts for at least 48 hours. Our study shows that the B. pinnipedialis strain isolated from hooded seal survives in Atlantic cod, and suggests that Atlantic cod could play a role in the transmission of B. pinnipedialis to hooded seals in the wild.

  5. Oral Outbreak of Chagas Disease in Santa Catarina, Brazil: Experimental Evaluation of a Patient’s Strain

    PubMed Central

    Domingues, Carolina S.; Hardoim, Daiana J.; Souza, Celeste S. F.; Cardoso, Flávia O.; Mendes, Verônica G.; Previtalli-Silva, Henrique; Abreu-Silva, Ana L.; Pelajo-Machado, Marcelo; Gonçalves da Costa, Sylvio Celso; Calabrese, Kátia S.

    2015-01-01

    Chagas disease is a worldwide public health problem. Although the vectorial transmission of Chagas disease has been controlled in Brazil there are other ways of transmission, such as the ingestion of T. cruzi contaminated food, which ensures the continuation of this zoonosis. Here, we demonstrate the influence of the inoculation route on the establishment and development of the SC2005 T. cruzi strain infection in mice. Groups of Swiss mice were infected intragastrically (IG) or intraperitoneally (IP) with the T. cruzi SC2005 strain derived from an outbreak of oral Chagas disease. The results revealed that 100% of IP infected mice showed parasitemia, while just 36% of IG infected showed the presence of the parasite in blood. The parasitemia peaks were later and less intense in the IG infected mice. Mortality of the IP infected animals was more intense and earlier when compared to the IG infected mice. In the IP infected mice leucopenia occurred in the early infection followed by leucocytosis, correlating positively with the increase of the parasites. However, in the IG infected mice only an increase in monocytes was observed, which was positively correlated with the increase of the parasites. Histopathological analyses revealed a myotropic pattern of the SC2005 strain with the presence of inflammatory infiltrates and parasites in different organs of the animals infected by both routes as well as fibrosis foci and collagen redistribution. The flow cytometric analysis demonstrated a fluctuation of the T lymphocyte population in the blood, spleen and mesenteric lymph nodes of the infected animals. T. cruzi DNA associated with the presence of inflammatory infiltrates was detected by PCR in the esophagus, stomach and intestine of all infected mice. These findings are important for the understanding of the pathogenesis of T. cruzi infection by both inoculation routes. PMID:26469517

  6. Comparison tests and experimental compliance calibration of the proposed standard round compact plane strain fracture toughness specimen

    NASA Technical Reports Server (NTRS)

    Fisher, D. M.; Buzzard, R. J.

    1979-01-01

    Standard round specimen fracture test results compared satisfactorily with results from standard rectangular compact specimens machined from the same material. The location of the loading pin holes was found to provide adequate strength in the load bearing region for plane strain fracture toughness testing. Excellent agreement was found between the stress intensity coefficient values obtained from compliance measurements and the analytic solution proposed for inclusion in the standard test method. Load displacement measurements were made using long armed displacement gages and hollow loading cylinders. Gage points registered on the loading hole surfaces through small holes in the walls of the loading cylinders.

  7. Experimental and numerical thermo-mechanical analysis of shape memory alloy subjected to tension with various stress and strain rates

    NASA Astrophysics Data System (ADS)

    Dunić, V.; Pieczyska, E. A.; Tobushi, H.; Staszczak, M.; Slavković, R.

    2014-05-01

    TiNi shape memory alloy (SMA) is experimentally and numerically investigated in tension tests under different loading rates. The thermomechanical behaviour of the SMA, related to the stress-induced martensitic transformation (SIMT) noticed during the experimental tests, is analysed and the observations are considered for numerical analysis. Initiation, development and saturation of the SIMT are monitored by a fast and sensitive infrared camera. The estimated temperature changes of the SMA sample, related to the exothermic martensitic forward and endothermic reverse transformation, have been analysed with the focus on the rate-dependent response and on the influence of the heat transfer on the mechanical behaviour. The effectively modified constitutive model, proposed by Lagoudas, is implemented in structural PAK finite element method (FEM) software and is thermomechanically coupled with the heat transfer FEM software in a partitioned approach. The experimental results are quantitatively and qualitatively reproduced by the numerical FEM model, which verifies the efficiency and accuracy of the proposed investigation method.

  8. Comparative experimental investigation on the efficacy of mono- and multiprobiotic strains in non-alcoholic fatty liver disease prevention.

    PubMed

    Kobyliak, Nazarii; Falalyeyeva, Tetyana; Virchenko, Oleksandr; Mykhalchyshyn, Galyna; Bodnar, Petro; Spivak, Mykola; Yankovsky, Dmytro; Beregova, Tetyana; Ostapchenko, Lyudmyla

    2016-03-15

    To investigate the efficacy of different probiotic strains, their combinations and forms (alive or lyophilized) in nonalcoholic fatty liver disease (NAFLD) prevention. In this study, 70 rats have been used divided into 7 groups of 10 animals in each: I - intact rats, II-VII - rats with monosodium glutamate (MSG)-induced NAFLD. Rats with NAFLD were untreated (group II, MSG-obesity group) and treated with probiotics (groups III-VII). In order to develop NAFLD, newborn rats of groups II-VII were injected with a solution of monosodium glutamate (MSG) (4 mg/g) subcutaneously (s.c.) at 2nd,4th, 6th, 8th,10th postnatal day. The groups III-V received lyophilized monoprobiotics B. animalis VKL, B. animalis VKB, L.casei IMVB-7280, respectively. The group VI received 2.5 ml/kg of an aqueous solution of a mixture of the three probiotic strains (2:1:1 Lactobacillus casei IMVB-7280, Bifidobacterium animalis VKL, Bifidobacterium animalis VKB) at a dose of 50 mg/kg (5 × 10(9) CFU/kg) (g) (intragastrically). The group VII was treated with multiprobiotic "Symbiter" containing biomass of 14 alive probiotic strains (Lactobacillus + Lactococcus (6 × 10(10) CFU/g), Bifidobacterium (1 × 10(10)/g), Propionibacterium (3 × 10(10)/g), Acetobacter (1 × 10(6)/g)) at a dose of 140 mg/kg (1.4 × 10(10) CFU/kg). The treatment with probiotics was started at the age of 1 month. There were 3 courses of treatment, each included 2-week administration and 2-week break. All parameters were measured in 4-month aged rats. Introduction of MSG during the neonatal period leads to the NAFLD development in the 4-months old rats. For steatosis degree there was no significant difference between MSG-obesity group and lyophilized monocomponent probiotics groups (III-V). The highest manifestation of steatosis was observed for B. animalis VKL group (2.0 ± 0.25) as compared to B. animalis VKB (1.70 ± 0.21) and L. casei IMVB-7280 (1.80 ± 0.20). The steatosis score changes between all monoprobiotics groups (III

  9. Experimental and Computational Investigation of the Shearing Resistance of an Elastomer at Pressures Up to 18 GPa and Strain Rates of 105 -106s-1

    NASA Astrophysics Data System (ADS)

    Jiao, Tong; Clifton, Rodney

    2015-06-01

    Pressure-shear plate impact (PSPI) experiments have been conducted to study the mechanical response of an elastomer (polyurea) at high pressures and high strain rates. The previously determined isentrope has been extended to 18 GPa. At this pressure, the high-strain-rate shearing resistance of polyurea is approximately 1 GPa-comparable to, or greater than, that of high strength steels and at much lower weight. From the PSPI experiments it is evident that the shearing resistance of polyurea increases essentially proportionately with increasing pressure. Polyurea's response to volumetric changes is largely reversible whereas its response to distortional changes is largely dissipative. These effects are modeled by introducing a constitutive model that incorporates a finite deformation isotropic elasticity model for the instantaneous response and a quasilinear viscoelasticity model-with distributed relaxation times-to model relaxation from the instantaneous elastic response. In order to model a dependence of shear wave speed on pressure, the strain energy function for the instantaneous elastic response is comprised of a distortion-dependent term multiplied by a factor that depends only on the change in volume. This model has been implemented into Abaqus™ to simulate the response of polyurea P1000 under the impact conditions of a variety of PSPI experiments. Results of these simulations suggest that the main features of the experimental results can be explained by such a model.

  10. Deciphering the Draft Genome of Toxoplasma gondii RH Strain

    PubMed Central

    Gudimella, Ranganath; Zhang, GuiPing; Ching, Xiao-Teng; Razali, Rozaimi; Aziz, Farhanah; Anwar, Arif; Fong, Mun-Yik

    2016-01-01

    Toxoplasmosis is a widespread parasitic infection by Toxoplasma gondii, a parasite with at least three distinct clonal lineages. This article reports the whole genome sequencing and de novo assembly of T. gondii RH (type I representative strain), as well as genome-wide comparison across major T. gondii lineages. Genomic DNA was extracted from tachyzoites of T. gondii RH strain and its identity was verified by PCR and LAMP. Subsequently, whole genome sequencing was performed, followed by sequence filtering, genome assembly, gene annotation assignments, clustering of gene orthologs and phylogenetic tree construction. Genome comparison was done with the already archived genomes of T. gondii. From this study, the genome size of T. gondii RH strain was found to be 69.35Mb, with a mean GC content of 52%. The genome shares high similarity to the archived genomes of T. gondii GT1, ME49 and VEG strains. Nevertheless, 111 genes were found to be unique to T. gondii RH strain. Importantly, unique genes annotated to functions that are potentially critical for T. gondii virulence were found, which may explain the unique phenotypes of this particular strain. This report complements the genomic archive of T. gondii. Data obtained from this study contribute to better understanding of T. gondii and serve as a reference for future studies on this parasite. PMID:27355363

  11. Mouse-adapted scrapie strains 139A and ME7 overcome species barrier to induce experimental scrapie in hamsters and changed their pathogenic features.

    PubMed

    Shi, Qi; Zhang, Bao-Yun; Gao, Chen; Zhang, Jin; Jiang, Hui-Ying; Chen, Cao; Han, Jun; Dong, Xiao-Ping

    2012-03-09

    Transmissible spongiform encephalopathy (TSE) diseases are known to be zoonotic diseases that can infect different kinds of animals. The transmissibility of TSE, like that of other infectious diseases, shows marked species barrier, either being unable to infect heterologous species or difficult to form transmission experimentally. The similarity of the amino acid sequences of PrP among species is believed to be one of the elements in controlling the transmission TSE interspecies. Other factors, such as prion strains and host's microenvironment, may also participate in the process. Two mouse-adapted strains 139A and ME7 were cerebrally inoculated to Golden hamsters. Presences of scrapie associate fibril (SAF) and PrPSc in brains of the infected animals were tested by TEM assays and Western blots dynamically during the incubation periods. The pathogenic features of the novel prions in hamsters, including electrophoretic patterns, glycosylating profiles, immunoreactivities, proteinase K-resistances and conformational stabilities were comparatively evaluated. TSE-related neuropathological changes were assayed by histological examinations. After long incubation times, mouse-adapted agents 139A and ME7 induced experimental scrapie in hamsters, respectively, showing obvious spongiform degeneration and PrPSc deposits in brains, especially in cortex regions. SAF and PrPSc in brains were observed much earlier than the onset of clinical symptoms. The molecular characteristics of the newly-formed PrPSc in hamsters, 139A-ha and ME7-ha, were obviously distinct from the original mouse agents, however, greatly similar as that of a hamster-adapted scrapie strain 263 K. Although the incubation times and main disease signs of the hamsters of 139A-ha and ME7-ha were different, the pathogenic characteristics and neuropathological changes were highly similar. This finding concludes that mouse-adapted agents 139A and ME7 change their pathogenic characteristics during the transmission to

  12. Experimental pig-to-pig transmission dynamics for African swine fever virus, Georgia 2007/1 strain.

    PubMed

    Guinat, C; Gubbins, S; Vergne, T; Gonzales, J L; Dixon, L; Pfeiffer, D U

    2016-01-01

    African swine fever virus (ASFV) continues to cause outbreaks in domestic pigs and wild boar in Eastern European countries. To gain insights into its transmission dynamics, we estimated the pig-to-pig basic reproduction number (R 0) for the Georgia 2007/1 ASFV strain using a stochastic susceptible-exposed-infectious-recovered (SEIR) model with parameters estimated from transmission experiments. Models showed that R 0 is 2·8 [95% confidence interval (CI) 1·3-4·8] within a pen and 1·4 (95% CI 0·6-2·4) between pens. The results furthermore suggest that ASFV genome detection in oronasal samples is an effective diagnostic tool for early detection of infection. This study provides quantitative information on transmission parameters for ASFV in domestic pigs, which are required to more effectively assess the potential impact of strategies for the control of between-farm epidemic spread in European countries.

  13. A method for assessing the fit of a constitutive material model to experimental stress-strain data.

    PubMed

    Morrow, Duane A; Donahue, Tammy Haut; Odegard, Gregory M; Kaufman, Kenton R

    2010-01-01

    Higher-order polynomial functions can be used as a constitutive model to represent the mechanical behaviour of biological materials. The goal of this study was to present a method for assessing the fit of a given constitutive three-dimensional material model. Goodness of fit was assessed using multiple parameters including the root mean square error and Hotelling's T 2-test. Specifically, a polynomial model was used to characterise the stress-strain data, varying the number of model terms used (45 combinations of between 3 and 11 terms) and the manner of optimisation used to establish model coefficients (i.e. determining coefficients either by parameterisation of all data simultaneously or averaging coefficients obtained by parameterising individual data trials). This framework for model fitting helps to ensure that a given constitutive formulation provides the best characterisation of biological material mechanics.

  14. Efficacy of Dart or Booster Vaccination with Strain RB51 in Protecting Bison against Experimental Brucella abortus Challenge

    PubMed Central

    Johnson, C. S.

    2012-01-01

    This study characterized the efficacy of the Brucella abortus strain RB51 vaccine in bison when delivered by single intramuscular vaccination (hand RB51), by single pneumatic dart delivery (dart RB51), or as two vaccinations approximately 13 months apart (booster RB51) in comparison to control bison. All bison were challenged intraconjunctivally in midgestation with 107 CFU of B. abortus strain 2308 (S2308). Bison were necropsied and sampled within 72 h of abortion or delivery of a live calf. Compared to nonvaccinated bison, bison in the booster RB51 treatment had a reduced (P < 0.05) incidence of abortion, uterine infection, or infection in maternal tissues other than the mammary gland at necropsy. Bison in single-vaccination treatment groups (hand RB51 and dart RB51) did not differ (P > 0.05) from the control group in the incidence of abortion or recovery of S2308 from uterine, mammary, fetal, or maternal tissues at necropsy. Compared to nonvaccinated animals, all RB51 vaccination groups had reduced (P < 0.05) mean colonization or incidence of infection in at least 2 of 4 target tissues, with the booster RB51 group having reduced (P < 0.05) colonization and incidence of infection in all target tissues. Our data suggest that booster vaccination of bison with RB51 enhances protective immunity against Brucella challenge compared to single vaccination with RB51 by hand or by pneumatic dart. Our study also suggests that an initial vaccination of calves followed by booster vaccination as yearlings should be an effective strategy for brucellosis control in bison. PMID:22496493

  15. Mapping of regional myocardial strain and work during ventricular pacing: experimental study using magnetic resonance imaging tagging.

    PubMed

    Prinzen, F W; Hunter, W C; Wyman, B T; McVeigh, E R

    1999-05-01

    The purpose of this study was to determine the spatial distribution of myocardial function (myofiber shortening and work) within the left ventricular (LV) wall during ventricular pacing. Asynchronous electrical activation, as induced by ventricular pacing, causes various abnormalities in LV function, perfusion and structure. These derangements may be caused by abnormalities in regional contraction patterns. However, insight into these patterns during pacing is as yet limited. In seven anesthetized dogs, high spatial and temporal resolution magnetic resonance-tagged images were acquired in three orthogonal planes. Three-dimensional deformation data and LV cavity pressure and volume were used to determine midwall circumferential strain and external and total mechanical work at 192 sites around the left ventricle. During ventricular pacing, systolic fiber strain and external work were approximately zero in regions near the pacing site, and gradually increased to more than twice the normal value in the most remote regions. Total mechanical work, normalized to the value during right atrial pacing, was 38 +/- 13% (right ventricular apex [RVapex] pacing) and 61 +/- 23% (left ventricular base [LVbase] pacing) close to the pacing site, and 125 +/- 48% and 171 +/- 60% in remote regions, respectively (p < 0.05 between RVapex and LVbase pacing). The number of regions with reduced work was significantly larger during RVapex than during LVbase pacing. This was associated with a reduction of global LV pump function during RVapex pacing. Ventricular pacing causes a threefold difference in myofiber work within the LV wall. This difference appears large enough to regard local myocardial function as an important determinant for abnormalities in perfusion, metabolism, structure and pump function during asynchronous electrical activation. Pacing at sites that cause more synchronous activation may limit the occurrence of such derangements.

  16. Efficacy of dart or booster vaccination with strain RB51 in protecting bison against experimental Brucella abortus challenge.

    PubMed

    Olsen, S C; Johnson, C S

    2012-06-01

    This study characterized the efficacy of the Brucella abortus strain RB51 vaccine in bison when delivered by single intramuscular vaccination (hand RB51), by single pneumatic dart delivery (dart RB51), or as two vaccinations approximately 13 months apart (booster RB51) in comparison to control bison. All bison were challenged intraconjunctivally in midgestation with 10(7) CFU of B. abortus strain 2308 (S2308). Bison were necropsied and sampled within 72 h of abortion or delivery of a live calf. Compared to nonvaccinated bison, bison in the booster RB51 treatment had a reduced (P < 0.05) incidence of abortion, uterine infection, or infection in maternal tissues other than the mammary gland at necropsy. Bison in single-vaccination treatment groups (hand RB51 and dart RB51) did not differ (P > 0.05) from the control group in the incidence of abortion or recovery of S2308 from uterine, mammary, fetal, or maternal tissues at necropsy. Compared to nonvaccinated animals, all RB51 vaccination groups had reduced (P < 0.05) mean colonization or incidence of infection in at least 2 of 4 target tissues, with the booster RB51 group having reduced (P < 0.05) colonization and incidence of infection in all target tissues. Our data suggest that booster vaccination of bison with RB51 enhances protective immunity against Brucella challenge compared to single vaccination with RB51 by hand or by pneumatic dart. Our study also suggests that an initial vaccination of calves followed by booster vaccination as yearlings should be an effective strategy for brucellosis control in bison.

  17. Experimental and theoretical study of polarized photoluminescence caused by anisotropic strain relaxation in nonpolar a-plane textured ZnO grown by a low-pressure chemical vapor deposition

    SciTech Connect

    Lai, Chih-Ming; Huang, Yu-En; Feng, Shih-Wei; Kou, Kuang-Yang; Chen, Chien-Hsun; Tu, Li-Wei

    2015-07-13

    Anisotropic strain relaxation and the resulting degree of polarization of photoluminescence (PL) in nonpolar a-plane textured ZnO are experimentally and theoretically studied. A thicker nonpolar a-plane textured ZnO film enhances the anisotropic in-plane strain relaxation, resulting in a larger degree of polarization of PL and better sample quality. Anisotropic in-plane strains, sample quality, and degree of polarization of PL in nonpolar a-plane ZnO are consequences of the degree of anisotropic in-plane strain relaxation. By the k·p perturbation approach, simulation results of the variation of the degree of polarization for the electronic transition upon anisotropic in-plane strain relaxation agree with experimental results.

  18. Genetic resistance to the induction of experimental allergic encephalomyelitis in Lewis rats. I. Genetic analysis of an apparent mutant strain with phenotypic resistance to experimental allergic encephalomyelitis.

    PubMed

    Waxman, F J; Perryman, L E; Hinrichs, D J; Coe, J E

    1981-01-01

    Clinical resistance to the induction of experimental allergic encephalomyelitis was observed in a closed colony of Lewis (designated Le-R) rats. Disease susceptibility in randomly bred animals appeared to increase with increasing age. In the small group of young Le-R rats, which were susceptible, disease onset was delayed, severity of symptoms was reduced, and duration of clinical signs was abbreviated compared to conventional Lewis rats. The severity of histologic neural tissue lesions correlated with clinical observations. Breeding experiments indicated that most Le-R rats were resistant to disease induction regardless of whether their ancestors had been selected for susceptibility or resistance. The F3 generation of resistant lineage was uniformly resistant at all ages tested. Virtually all (Lewis X Le-R)F1 rats of either sex were resistant when challenged at 7-8 wk of age indicating that resistance was a dominant autosomal trait. Approximately half of (F1 X Lewis) backcross rats developed paralytic EAE whereas one-fourth were entirely resistant, suggesting that disease resistance may be mediated by one or two genes. Le-R rats shared at least some of the Lewis rat major histocompatibility antigens. Resistance apparently did not reflect a nonspecific impairment of cellular immune responsiveness. Le-R rats, which had been challenged with myelin basic protein, developed antigen-reactive cells specific for basic protein or its encephalitogenic fragment. Spleen cells obtained from basic protein-sensitized Le-R rats did not adoptively transfer disease into Lewis rats. In contrast, spleen cells obtained from basic protein-sensitized Lewis rats readily transferred disease into both Lewis and Le-R recipients. These data suggest that disease resistance may be a result of an immunologic deficit (or suppressor cell activity) expressed during the differentiation of antigen-reactive cells into disease-inducing effector cells.

  19. Experimental infection of six North American fish species with the North Carolina strain of spring Viremia of Carp Virus

    USGS Publications Warehouse

    Emmenegger, Eveline J.; Sanders, George E.; Conway, Carla M.; Binkowski, Fred P.; Winton, James R.; Kurath, Gael

    2016-01-01

    Three salmonid species, rainbow and steelhead trout (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha), and sockeye salmon (O. nerka), were challenged by immersion or injection with the North Carolina SVCV isolate. Two cyprinid species, koi and fathead minnow (Pimephales promelas) and one percid species, yellow perch (Perca flavescens) were also challenged. Koi were highly susceptible to SVCV up to 11 months of age and fathead minnows had chronic disease expression with moderate mortality (29%). SVCV also induced moderate mortalities (33%) in yellow perch fry. Virus challenged salmonid fish had cumulative percent mortalities ranging from 0 to 100%, with sockeye salmon fry being the most vulnerable. A sub-sample of mortalities and survivors were screened for virus by plaque assay and reverse transcription polymerase chain reaction. In general, all mortalities tested positive for SVCV with high viral titers while survivors had variable persistence of SVCV with overall lower virus titers. Our SVCV challenges of multiple North American fish species suggested that host age is a key factor in determining disease outcome. Other factors, such as fish broodstock, virus strain, water temperature, and rearing conditions in association with the intrinsic level of species susceptibility may also impact infection dynamics. This is the first report of SVCV infecting a species (yellow perch) in the family Percidae and that sockeye salmon fry can suffer similarly high mortalities as the primary SVCV host species.

  20. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium.

    PubMed

    Ben Khedher, Saoussen; Jaoua, Samir; Zouari, Nabil

    2013-01-01

    In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L(-1) starch, 30 g L(-1) soya bean and 9 g L(-1) sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.

  1. Defect induced structural-scaling transitions and shock waves evolution in large range of strain rates (experimental and theoretical study)

    NASA Astrophysics Data System (ADS)

    Naimark, Oleg; Bayandin, Yuri; Zocher, Marvin; Preston, Dean

    2009-06-01

    Statistically based phenomenology allowed formulation of thermodynamic potential and constitutive equations to establish link of defect induced structural-scaling transition, plastic flow and damage-failure transition. Relaxation properties of metals in strain rate range 10^3 10^10s-1 were analyzed that allowed interpretation: (i) self-similarity of shock wave profile for different stress amplitudes, mechanism of generation of second ``elastic precursor'' under reloading tests; (ii) mechanism of transition from thermally activated dislocation glide to regime of steady-state plastic wave and overdriven shock. Comparison of MTS-PTW and statistically based models allowed link hardening law, saturation stress and yield stress in thermal activation regime with non-linearity of thermodynamic potential, to propose interpretation of ``singularity gap'' between thermally activated dislocation glide and overdriven-shock regimes. Using 3D New View profilometry data correspondence of defect induced relaxation properties and multiscale correlation in defects ensemble was established for vanadium recovered specimens subject to quasi-static, dynamic and plate impact tests.

  2. Virus distribution and detection in corn snakes (Pantherophis guttatus) after experimental infection with three different ferlavirus strains.

    PubMed

    Pees, Michael; Neul, Annkatrin; Müller, Kristin; Schmidt, Volker; Truyen, Uwe; Leinecker, Nadja; Marschang, Rachel E

    2016-01-15

    Ferlaviruses are important pathogens of snakes. However, factors influencing the pathogenicity of individual isolates as well as optimal protocols for virus detection in tissues of infected snakes have been insufficiently studied. The objectives of this study were to compare virus detection using previously described PCR and cell culture protocols following infection with three genetically distinct ferlaviruses in corn snakes (Pantherophis guttatus) as a model species. Groups of 12 corn snakes were each inoculated intratracheally with a genogroup A, B, or C ferlavirus. Tracheal washes and cloacal swabs were tested for virus shedding on days 16 and 28. Three animals were each euthanized on days 4, 16, 28, and 49. Beside immunohistochemistry of lung tissue, several organs (lung, intestine, pancreas, kidney, brain) were tested for the presence of ferlavirus. Distinct differences were noted in the pathogenicity of the three viruses, with a genotype B isolate causing the greatest pathology. PCR was more sensitive in comparison to cell culture, but results varied depending on the tissues. Ferlaviruses spread rapidly into the tissues, including the brain. Overall average detection rate was 72%, and was highest on day 16. There were differences between the groups, with the most virulent strain causing 100% positive samples at the end of the study. Some snakes were able to clear the infection. Shedding via cloaca was seen only on day 28. For ante-mortem sampling, a tracheal wash sample is recommended, for post mortem diagnosis, a pooled organ sample should be tested.

  3. Numerical simulation and experimental validation of a large-area capacitive strain sensor for fatigue crack monitoring

    NASA Astrophysics Data System (ADS)

    Kong, Xiangxiong; Li, Jian; Bennett, Caroline; Collins, William; Laflamme, Simon

    2016-12-01

    A large-area electronics in the form of a soft elastomeric capacitor (SEC) has shown great promise as a strain sensor for fatigue crack monitoring in steel structures. The SEC sensors are inexpensive, easy to fabricate, highly stretchable, and mechanically robust. It is a highly scalable technology, capable of monitoring deformations on mesoscale systems. Preliminary experiments verified the SEC sensor’s capability in detecting, localizing, and monitoring crack growth in a compact specimen. Here, a numerical simulation method is proposed to simulate accurately the sensor’s performance under fatigue cracks. Such a method would provide a direct link between the SEC’s signal and fatigue crack geometry, extending the SEC’s capability to dense network applications on mesoscale structural components. The proposed numerical procedure consists of two parts: (1) a finite element (FE) analysis for the target structure to simulate crack growth based on an element deletion method; (2) an algorithm to compute the sensor’s capacitance response using the FE analysis results. The proposed simulation method is validated based on test data from a compact specimen. Results from the numerical simulation show good agreement with the SEC’s response from the laboratory tests as a function of the crack size. Using these findings, a parametric study is performed to investigate how the SEC would perform under different geometries. Results from the parametric study can be used to optimize the design of a dense sensor network of SECs for fatigue crack detection and localization.

  4. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium

    PubMed Central

    Ben Khedher, Saoussen; Jaoua, Samir; Zouari, Nabil

    2013-01-01

    In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L−1 starch, 30 g L−1 soya bean and 9 g L−1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view. PMID:24516462

  5. Application of bioinformatics-coupled experimental analysis reveals a new transport-competent nuclear localization signal in the nucleoprotein of Influenza A virus strain

    PubMed Central

    Ketha, Krishna Mohan V; Atreya, Chintamani D

    2008-01-01

    Background Two nuclear localization sequences (NLS) in influenza A virus nucleoprotein (NP) have been demonstrated to be critical for nuclear import of NP and viral ribonucleoprotein complexes. However, a deletion mutant lacking these two signals was still able to localize to the nucleus suggesting the presence of yet another (a third) potential NLS in the NP protein. In order to identify the nature of this potential NLS signal in the NP of a WS/33L influenza virus A strain, we utilized the tools of bioinformatics coupled with functional experimental analyses in the present study. Results Comparison of the deduced aa sequence of NP of WS/33L strain with the published WS/33 NP sequences revealed that a single amino acid (aa) change (Met to Arg) at position 105 results in converting the flanking regions (between aa position 90–121, a 32-residue stretch) into two classical overlapping bipartite NLS (obpNLS). GenBank search revealed that 9 out of 500 published NP sequences contain a similar Arg at position 105 (instead of Met) with a 100% homology to the obpNLS region. Various NP-green fluorescent protein (GFP) fusion constructs with and without the signal (obpNLS-Arg105) were utilized to understand the functional nature of this signal. We analyzed the transport competency of the expressed chimeric proteins in terms of their cellular localization by confocal immunofluorescence assay. Our analysis revealed that all NP-GFP constructs containing the wild-type (R105) sequence localized predominantly to the nucleus. Constructs lacking the obpNLS or constructs with reverse mutation (R105 to M105) on the other hand exhibited predominant cytoplasmic localization pattern. Interestingly, when the 32 aa obpNLS was fused with an unrelated viral protein (rotavirus NSP6) that has been known to be cytoplasmic protein, the chimeric protein (obpNLS-NSP6) was efficiently transported into the nucleus, indicating an efficient nuclear transport function of the 32-residue obpNLS in the NP

  6. Experimental Gonococcal Infection in Male Volunteers: Cumulative Experience with Neisseria Gonorrhoeae Strains FA1090 and MS11mkC

    DTIC Science & Technology

    2011-05-31

    unpublished data from J. G. Can- non ) and 43 men inoculated with wild-type FA1090 at doses from 1.0× 104 to 3.5× 106 cfu (Cohen et al., 1994 and unpublished...each dose response curve was tested using the Hosmer–Lemeshow statistic (Hosmer and Lemeshow, 2000). A non -significant P value (>0.05) indi- cates a...responses including production of specific anti- bodies are generally thought to require longer exposure than occurs during experimental infection

  7. On the role of delocalization in benzene: Theoretical and experimental investigation of the effects of strained ring fusion

    SciTech Connect

    Faust, Rudiger

    1993-04-01

    When an important compound`s discovery dates back as far as 1825, one would imagine that every facet of its chemical and physical properties has been illuminated in the meantime. Benzene, however, has not ceased to challenge the chemist`s notion of structure and bonding since its first isolation by Michael Faraday. This report is divided into the following six chapters: 1. Aromaticity -- Criteria, manifestations, structural limitations; 2. The role of delocalization in benzene; 3. The thermochemical properties of benzocyclobutadienologs; 4. Ab initio study of benzenes fused to four-membered rings; 5. Non-planar polycyclic aromatic hydrocarbons; and 6. Experimental details and input decks. 210 Refs.

  8. Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach; Progress Report for 2004

    SciTech Connect

    I. Robertson; A. Beaudoin; J. Lambros

    2005-01-31

    Development and validation of constitutive models for polycrystalline materials subjected to high strain rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be closely coupled with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experimentation is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models, which will include dislocation-grain boundary interactions for polycrystalline systems. One aspect of the program will involve the direct observation

  9. Experimental Evolution of Legionella pneumophila in Mouse Macrophages Leads to Strains with Altered Determinants of Environmental Survival

    PubMed Central

    Ensminger, Alexander W.; Yassin, Yosuf; Miron, Alexander; Isberg, Ralph R.

    2012-01-01

    The Gram-negative bacterium, Legionella pneumophila, is a protozoan parasite and accidental intracellular pathogen of humans. We propose a model in which cycling through multiple protozoan hosts in the environment holds L. pneumophila in a state of evolutionary stasis as a broad host-range pathogen. Using an experimental evolution approach, we tested this hypothesis by restricting L. pneumophila to growth within mouse macrophages for hundreds of generations. Whole-genome resequencing and high-throughput genotyping identified several parallel adaptive mutations and population dynamics that led to improved replication within macrophages. Based on these results, we provide a detailed view of the population dynamics of an experimentally evolving bacterial population, punctuated by frequent instances of transient clonal interference and selective sweeps. Non-synonymous point mutations in the flagellar regulator, fleN, resulted in increased uptake and broadly increased replication in both macrophages and amoebae. Mutations in multiple steps of the lysine biosynthesis pathway were also independently isolated, resulting in lysine auxotrophy and reduced replication in amoebae. These results demonstrate that under laboratory conditions, host restriction is sufficient to rapidly modify L. pneumophila fitness and host range. We hypothesize that, in the environment, host cycling prevents L. pneumophila host-specialization by maintaining pathways that are deleterious for growth in macrophages and other hosts. PMID:22693450

  10. Pathology of experimental Machupo virus infection, Chicava strain, in cynomolgus macaques (Macaca fascicularis) by intramuscular and aerosol exposure.

    PubMed

    Bell, T M; Shaia, C I; Bunton, T E; Robinson, C G; Wilkinson, E R; Hensley, L E; Cashman, K A

    2015-01-01

    Machupo virus, the causative agent of Bolivian hemorrhagic fever (BHF), is a highly lethal viral hemorrhagic fever of which little is known and for which no Food and Drug Administration-approved vaccines or therapeutics are available. This study evaluated the cynomolgus macaque as an animal model using the Machupo virus, Chicava strain, via intramuscular and aerosol challenge. The incubation period was 6 to 10 days with initial signs of depression, anorexia, diarrhea, mild fever, and a petechial skin rash. These were often followed by neurologic signs and death within an average of 18 days. Complete blood counts revealed leukopenia as well as marked thrombocytopenia. Serum chemistry values identified a decrease in total protein, marked increases in alanine aminotransferase and aspartate aminotransferase, and moderate increases in alkaline phosphatase. Gross pathology findings included a macular rash extending across the axillary and inguinal regions beginning at approximately 10 days postexposure as well as enlarged lymph nodes and spleen, enlarged and friable liver, and sporadic hemorrhages along the gastrointestinal mucosa and serosa. Histologic lesions consisted of foci of degeneration and necrosis/apoptosis in the haired skin, liver, pancreas, adrenal glands, lymph nodes, tongue, esophagus, salivary glands, stomach, small intestine, and large intestine. Lymphohistiocytic interstitial pneumonia was also present. Inflammation within the central nervous system (nonsuppurative encephalitis) was histologically apparent approximately 16 days postexposure and was generally progressive. This study provides insight into the course of Machupo virus infection in cynomolgus macaques and supports the usefulness of cynomolgus macaques as a viable model of human Machupo virus infection. © The Author(s) 2014.

  11. Transient rheological behavior of natural polysaccharide xanthan gum solutions in start-up shear flow fields: An experimental study using a strain-controlled rheometer

    NASA Astrophysics Data System (ADS)

    Lee, Ji-Seok; Kim, Yong-Seok; Song, Ki-Won

    2015-08-01

    The objective of the present study is to experimentally investigate the transient rheological behavior of concentrated xanthan gum solutions in start-up shear flow fields. Using a strain-controlled rheometer, a number of constant shear rates were suddenly imposed to aqueous xanthan gum solutions with different concentrations and the resultant shear stress responses were measured with time. The main findings obtained from this study can be summarized as follows: (1) For all shear rates imposed, however low it may be, the shear stress is rapidly increased with time (stress overshoot) upon inception of steady shear flow before passing through the maximum stress value and then gradually decreased with time (stress decay) until reaching a steady state flow. (2) As the imposed shear rate is increased, a more pronounced stress overshoot takes place and the maximum stress value becomes larger, whereas both times at which the maximum stress is observed and needed to reach a steady state flow are shortened. (3) The maximum shear stress is linearly increased with shear rate in a double logarithmic scale and becomes larger with increasing concentration at equal shear rates. In addition, the time at which the maximum stress occurs exhibits a linear relationship with the inverse of shear rate in a double logarithmic scale for all xanthan gum solutions, regardless of their concentrations. (4) The shear stress is sharply increased with an increase in strain until reaching the maximum stress at small range of deformations. The maximum stress is observed at similar strain values, irrespective of the imposed shear rates lower than 10 1/s. (5) The Bird-Leider model can be successfully used with regard to quantitatively predicting the transient behavior of concentrated xanthan gum solutions. However, this model has a fatal weakness in terms of describing a decrease in shear stress (stress decay).

  12. An experimental and modeling investigation of the external strain, internal stress and fiber phase transformation behavior of a NiTi actuated aluminum metal matrix composite

    SciTech Connect

    Armstrong, W.D.; Lorentzen, T.; Broendsted, P.; Larsen, P.H.

    1998-06-12

    The present work reports macroscopic thermal mechanical and in-situ neutron diffraction measurements from 22.9 vol. %, 50.7 at. % Ni-Ti fiber actuated 6082-T6 aluminum matrix composite and 6082-T6 homogeneous aluminum control materials subjected to a room temperature 4% tensile elongation, a subsequent room temperature to 120 C unconstrained heating process, and a final 120 C tensile process. During the unconstrained room temperature to 120 C heating process, the composite exhibited a pronounced, non linear thermal contraction, while the homogeneous control exhibited the expected linear thermal expansion. The composite thermal contraction was clearly the result of a powerful shape memory response in the actuating NiTi fibers. The paper further presents a one-dimensional thermal strain, internal stress and fiber phase transformation composite model. Model parameters were identified from tests on extracted single fibers, calculations using these parameters quantitatively agree with experimental thermal mechanical and neutron diffraction measurements.

  13. Interface simulation of strained and non-abrupt III-V quantum wells. Part 2: energy level calculation versus experimental data

    NASA Astrophysics Data System (ADS)

    Lamberti, C.

    1996-01-01

    This work describes a program able to compute the allowed energy levels and the respective wavefunctions of strained {In1 - xGaxAsyP1 - y}/{In1 - zGazAswP1 - w} for electrons, light and heavy holes in single- and multi-quantum wells and superlattices. Ground and excited states can be detected. The problem of non-abrupt interfaces has been taken into account. The computation on intentionally strained QW structures can be performed. The simulation of coupled wells may also be done, allowing theoretical prediction on the 4 K photoluminescence emission of superlattices. The adopted mathematical approach has been treated in details. The results of the presented simulations performed on heterostructures grown by low-pressure metallorganic vapor phase epitaxy and by chemical beam epitaxy heterostructures are compared with 4 K Fourier transform photoluminescence and with room temperature IR absorption data. The data used as input by this program are previously computed by the program BANDSTRAIN (described in a previous paper). In this work also the simulation of high resolution X-ray diffraction patterns is briefly presented and compared with the experimental curves; it is shown how the combined simulations of PL and X-ray data is a powerful tool in the interfaces characterization. Finally, qualitative information is extracted from high-resolution transmission electron microscopy micrographs.

  14. During acute experimental infection with the reticulotropic Trypanosoma cruzi strain Tulahuen IL-22 is induced IL-23-dependently but is dispensable for protection

    PubMed Central

    Erdmann, Hanna; Behrends, Jochen; Hölscher, Christoph

    2016-01-01

    Protective immunity against Trypanosoma cruzi, the causative agent of Chagas disease, depends on the activation of macrophages by IFN-γ and IL-17A. In contrast, IL-10 prevents immunopathology. IL-22 belongs to the IL-10 cytokine family and has pleiotropic effects during host defense and immunopathology, however its role in protection and pathology during T. cruzi infection has not been analyzed yet. Therefore, we examined the role of IL-22 in experimental Chagas disease using the reticulotropic Tulahuen strain of T. cruzi. During infection, IL-22 is secreted by CD4-positive cells in an IL-23-dependent fashion. Infected IL-22−/− mice exhibited an increased production of IFN-γ and TNF and displayed enhanced numbers of activated IFN-γ-producing T cells in their spleens. Additionally, the production of IL-10 was increased in IL-22−/− mice upon infection. Macrophage activation and by association the parasitemia was not affected in the absence of IL-22. Apart from a transient increase in the body weight loss, infected IL-22−/− mice did not show any signs for an altered immunopathology during the first fourteen days of infection. Taken together, although IL-22 is expressed, it seems to play a minor role in protection and pathology during the acute systemic infection with the reticulotropic Tulahuen strain of T. cruzi. PMID:27650379

  15. Accessing ultra-high pressures and strain rates in the solid state: An experimental path to extreme materials science on the Omega and NIF lasers

    NASA Astrophysics Data System (ADS)

    Lorenz, K. Thomas

    2005-03-01

    A new approach to materials science at extreme pressures and strain rates has been developed on the Omega laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample nearly isentropically. The peak pressure on the sample, diagnosed with VISAR measurements, can be varied by adjusting the laser energy and pulse length, gap size, and reservoir density, and obeys a simple scaling relation.^1 This has been demonstrated at OMEGA at pressures to 200 GPa in Al foils. In an important application, using in-flight x-ray radiography, the material strength of solid-state samples at high pressure can be inferred by measuring the reductions in the growth rates (stabilization) of Rayleigh-Taylor (RT) unstable interfaces. RT instability measurements of solid Al-6061-T6 and vanadium, at pressures of 20-100 GPa and strain rates of 10^6 to 10^8 s-1, show clear material strength effects. High-pressure experimental designs based on this drive have been developed for the NIF laser, predicting that solid-state samples can be quasi-isentropically driven to pressures an order of magnitude higher than on Omega - accessing new regimes of dense, high-pressure matter. [1] J. Edwards et al., Phys. Rev. Lett., 92, 075002 (2004).

  16. Experimental characterization of post rigor mortis human muscle subjected to small tensile strains and application of a simple hyper-viscoelastic model.

    PubMed

    Gras, Laure-Lise; Laporte, Sébastien; Viot, Philippe; Mitton, David

    2014-10-01

    In models developed for impact biomechanics, muscles are usually represented with one-dimensional elements having active and passive properties. The passive properties of muscles are most often obtained from experiments performed on animal muscles, because limited data on human muscle are available. The aim of this study is thus to characterize the passive response of a human muscle in tension. Tensile tests at different strain rates (0.0045, 0.045, and 0.45 s⁻¹) were performed on 10 extensor carpi ulnaris muscles. A model composed of a nonlinear element defined with an exponential law in parallel with one or two Maxwell elements and considering basic geometrical features was proposed. The experimental results were used to identify the parameters of the model. The results for the first- and second-order model were similar. For the first-order model, the mean parameters of the exponential law are as follows: Young's modulus E (6.8 MPa) and curvature parameter α (31.6). The Maxwell element mean values are as follows: viscosity parameter η (1.2 MPa s) and relaxation time τ (0.25 s). Our results provide new data on a human muscle tested in vitro and a simple model with basic geometrical features that represent its behavior in tension under three different strain rates. This approach could be used to assess the behavior of other human muscles. © IMechE 2014.

  17. Action of phosphorylated mannanoligosaccharides on immune and hematological responses and fecal consistency of dogs experimentally infected with enteropathogenic Escherichia coli strains

    PubMed Central

    Gouveia, E.M.M.F.; Silva, I.S.; Nakazato, G.; Onselem, V.J.V.; Corrêa, R.A.C.; Araujo, F.R.; Chang, M.R.

    2013-01-01

    The therapeutic action of phosphorylated mannanoligosaccharides (MOS) was investigated regarding its prebiotic activity on enteropathogenic Escherichia coli (EPEC). Diarrhea was induced in dogs by experimental infection with EPEC strains. Then MOS was supplied once a day, in water for 20 days. Immunological (IgA and IgG), hematological (lymphocytes, neutrophils and monocytes) and bacteriological variables (PCR detection of the eae gene of EPEC recovered from stool culture), as well as occurrence of diarrhea were evaluated. All strains caused diarrhea at 24, 48 and 72 h after infection. PCR results indicated that E. coli isolated from stool culture of all infected animals had the eae gene. There was no significant difference among groups as to number of blood cells in the hemogram and IgA and IgG production. MOS was effective in recovering of EPEC-infected dogs since prebiotic-treated animals recovered more rapidly from infection than untreated ones (p < 0.05). This is an important finding since diarrhea causes intense dehydration and nutrient loss. The use of prebiotics for humans and other animals with diarrhea can be an alternative for the treatment and prophylaxis of EPEC infections. PMID:24294246

  18. Elastic strain at interfaces and its influence on ionic conductivity in nanoscaled solid electrolyte thin films--theoretical considerations and experimental studies.

    PubMed

    Schichtel, N; Korte, C; Hesse, D; Janek, J

    2009-05-07

    Ionic transport in solids parallel to grain or phase boundaries is usually strongly enhanced compared to the bulk. Transport perpendicular to an interface (across an interface) is often much slower. Therefore in modern micro- and nanoscaled devices, a severe influence on the ionic/atomic transport properties can be expected due to the high density of interfaces.Transport processes in boundaries of ionic materials are still not understood on an atomic scale. In most of the studies on ionic materials the interfacial transport properties are explained by the influence of space charge regions. Here we discuss the influence of interfacial strain at semicoherent or coherent heterophase boundaries on ionic transport along these interfaces in ionic materials. A qualitative model is introduced for (untilted and untwisted) hetero phase boundaries. For experimental verification, the interfacial oxygen ionic conductivity of different multilayer systems consisting of cubic ZrO(2) stabilised by aliovalent dopands (YSZ, CSZ) and an insulating oxide is investigated as a function of structural mismatch. Recent results on extremely fast ionic conduction in YSZ/SrTiO(3) thin film systems ("colossal ionic concuctivity at interfaces") is discussed from the viewpoint of strain effects.

  19. Pathogenicity of Nc-Bahia and Nc-1 strains of Neospora caninum in experimentally infected cows and buffaloes in early pregnancy.

    PubMed

    Chryssafidis, Andreas Lazaros; Cantón, Germán; Chianini, Francesca; Innes, Elisabeth A; Madureira, Ed Hoffmann; Gennari, Solange Maria

    2014-04-01

    Neospora caninum is a protozoan parasite known as an important cause of bovine abortion worldwide. Little is currently known about how different strains of N. caninum vary in their pathogenicity. In this study, we compared a Brazilian strain, Nc-Bahia, with the first isolate of this coccidian, Nc-1. Eight cows and seven buffaloes were submitted to fixed-time artificial insemination protocols for a better control of pregnancy. Group 1 was inoculated with Nc-Bahia (n = 8; five cows and three buffaloes), and Group 2 was inoculated with Nc-1 (n = 5; two cows and three buffaloes). One nonpregnant female of each species was left uninfected as sentinel controls for potential environmental infection. All inoculated animals received 5 × 10(8) tachyzoites of N. caninum, by intravenous route, on the 70th day of gestation. Uninfected animals remained seronegative throughout the experiment, indicating no exogenous infection, whereas all inoculated animals became seropositive to N. caninum. In Group 1, abortion was found in only one cow on 42 days postinfection (dpi; frequency of abortion = 12.5%), whilst all animals from Group 2 aborted on 35 dpi (frequency of abortion = 100%). Parasite DNA was detected by seminested PCR in maternal, foetal and placental tissues, confirming vertical transmission in Groups 1 and 2, although histological lesions had different frequencies and degrees of severity between the groups. There was evidence of lower pathogenicity of Nc-Bahia compared to Nc-1 when used in experimental infection, as it caused fewer abortions, as well as less frequent and milder histological lesions. This was the first time Nc-Bahia has been used for experimental infection.

  20. Experimental infections of Pacific oyster Crassostrea gigas using the Australian ostreid herpesvirus-1 (OsHV-1) µVar strain.

    PubMed

    Paul-Pont, Ika; Evans, Olivia; Dhand, Navneet K; Whittington, Richard J

    2015-03-09

    In Australia, the spread of the ostreid herpesvirus-1 microvariant (OsHV-1 µVar) threatens the Pacific oyster industry. There is an urgent need to develop an experimental infection model in order to study the pathogenesis of the virus under controlled laboratory conditions. The present study constitutes the first attempt to use archived frozen oysters as a source of inoculum, based on the Australian OsHV-1 µVar strain. Experiments were conducted to test (1) virus infectivity, (2) the dose-response relationship for OsHV-1, and (3) the best conditions in which to store infective viral inoculum. Intramuscular injection of a viral inoculum consistently led to an onset of mortality 48 h post-injection and a final cumulative mortality exceeding 90%, in association with high viral loads (1 × 105 to 3 × 107 copies of virus mg-1) in dead individuals. For the first time, an infective inoculum was produced from frozen oysters (tissues stored at -80°C for 6 mo). Storage of purified viral inoculum at +4°C for 3 mo provided similar results to use of fresh inoculum, whereas storage at -20°C, -80°C and room temperature was detrimental to infectivity. A dose-response relationship for OsHV-1 was identified but further research is recommended to determine the most appropriate viral concentration for development of infection models that would be used for different purposes. Overall, this work highlights the best practices and potential issues that may occur in the development of a reproducible and transferable infection model for studying the pathogenicity of the Australian OsHV-1 strain in Crassostrea gigas under experimental conditions.

  1. Morphologic lesions in type 2 BVDV infections experimentally induced by strain BVDV2-1373 recovered from a field case.

    PubMed

    Stoffregen, B; Bolin, S R; Ridpath, J F; Pohlenz, J

    2000-11-15

    Widespread outbreaks of severe acute BVDV, some associated with hemorrhagic syndrome (HS), were reported in Quebec and Ontario in 1993. These outbreaks caused significant economic hardship in infected herds. In the Ontario outbreak 150 dairy, 600 beef and 100 milk and grain fed veal herds were affected with losses estimated at $40000-$10000 per herd in lost animals, milk production, abortions and genetics. Fever, pneumonia, diarrhea, and sudden death occurred in all age groups of cattle. Abortions were frequently observed in pregnant cattle. The viruses associated with this outbreak were determined to be noncytopathic BVDV from the type 2 genotype. All BVDV2 associated with these outbreaks were noncytopathic. One of the viruses isolated from the Ontario outbreak, BVDV2-1373, was used to experimentally induce HS in 5-6 weeks old colostrum deprived, seronegative calves. All animals developed leukopenia and thrombocytopenia within 6-10 days with some developing bloody diarrhea and becoming moribund. Animals were killed for necropsy between 6 and 11 days postinfection. Histopathologically lesions were similar, but more severe, to those seen early on (within first 9 days after superinfection) in animals with experimentally induced mucosal disease (MD). There were no erosions and ulcerations present in the upper digestive tract. In hemorrhages in the mucosa, virus antigen (VA) was present in macrophages of both the lamina propria and the submucosa and in basal epithelial cells. Cells containing VA were vacuolated and separated from each other. The most severe lesions observed in the digestive tract were in the Peyers patches and were characterized by depletion of lymphocytes and proliferation of crypt cells resulting in crypthyperplasia. Apoptotic cells were present in crypts and areas of lymph follicles where viral antigen was detected. Out of the six animals, VA was present in four animals in the pancreas, three animals in the pituitary and in two animals in the

  2. The preventive effect of Bacillus subtilus strain DB9011 against experimental infection with enterotoxcemic Escherichia coli in weaning piglets.

    PubMed

    Tsukahara, Takamitsu; Tsuruta, Takeshi; Nakanishi, Nobuo; Hikita, Chie; Mochizuki, Masami; Nakayama, Keizo

    2013-04-01

    Porcine edema disease (ED) is caused by Shiga toxin 2e-producing Escherichia coli (STEC). Post-weaned piglets often suffer from ED as a result of intestinal infection with STEC, which causes impaired growth performance and high mortality. Antimicrobial therapy is a curative treatment for piglets infected with STEC, but the emergence of antimicrobial-resistant STEC has become a serious problem for Japanese pig farmers. Therefore, an alternative strategy other than antimicrobial therapy is needed for the prevention or treatment of ED. In this study, we evaluated the effect of oral administration of Bacillus subtilis DB9011 (DB9011) to prevent the experimental infection of STEC in weaning piglets. Eight 21-day-old piglets were divided into two groups: STEC challenge with the basal diet, and STEC challenge with DB9011 supplemented diet. The challenge was carried out when the animals were 25, 26 and 27 days old using STEC contained in capsules resistant against gastric digestion. All pigs were euthanized at 36 days of age. DB9011 improved the symptoms of ED and decreased the number of STEC in the ileal digesta and feces. Accordingly, oral administration of DB9011 in weaned piglets prevents ED through the suppression of the growth of STEC in the ileum.

  3. Collaborative study report: evaluation of the ATCC experimental mycoplasma reference strains panel prepared for comparison of NAT-based and conventional mycoplasma detection methods.

    PubMed

    Dabrazhynetskaya, Alena; Volokhov, Dmitriy V; Lin, Tsai-Lien; Beck, Brian; Gupta, Rajesh K; Chizhikov, Vladimir

    2013-11-01

    The main goal of this collaborative study was to evaluate the experimental panel of cryopreserved mycoplasma reference strains recently prepared by the American Type Culture Collection (ATCC(®)) in order to assess the viability and dispersion of cells in the mycoplasma stocks by measuring the ratio between the number of genomic copies (GC) and the number of colony forming units (CFU) in the reference preparations. The employment of microbial reference cultures with low GC/CFU ratios is critical for unbiased and reliable comparison of mycoplasma testing methods based on different methodological approaches, i.e., Nucleic Acid Testing (NAT) and compendial culture-based techniques. The experimental panel included ten different mycoplasma species known to represent potential human and animal pathogens as well as common contaminants of mammalian and avian cell substrates used in research, development, and manufacture of biological products. Fifteen laboratories with expertise in field of mycoplasma titration and quantification of mycoplasmal genomic DNA participated in the study conducted from February to October of 2012. The results of this study demonstrated the feasibility of preparing highly viable and dispersed (possessing low GC/CFU ratios) frozen stocks of mycoplasma reference materials, required for reliable comparison of NAT-based and conventional mycoplasma detection methods.

  4. Comparison between theoretical and experimental results for energy states of two-dimensional electron gas in pseudomorphically strained InAs high-electron-mobility transistors

    NASA Astrophysics Data System (ADS)

    Nishio, Yui; Tange, Takahiro; Hirayama, Naomi; Iida, Tsutomu; Takanashi, Yoshifumi

    2014-01-01

    The energy states of a two-dimensional electron gas (2DEG) in high-electron-mobility transistors with a pseudomorphically strained InAs channel (PHEMTs) were analyzed rigorously using a recently established theory that takes into account the nonparabolicity of the conduction band of the channel layer. The sheet density of the 2DEG in InxGa1-xAs-PHEMTs and the drain I-V characteristics of those devices were calculated theoretically and compared with the density and characteristics obtained experimentally. Not only the calculated threshold voltage (VTH) but also the calculated transconductance agreed fairly well with the corresponding values obtained experimentally. When the effects of the compositions of the InxGa1-xAs subchannel layer in the composite channel and the channel layer on energy states of 2DEG were investigated in order to establish a guiding principle for a design of the channel structure in PHEMTs, it was found that VTH is determined by the effective conduction-band offset energy ΔEC between the InAlAs barrier and the channel layers.

  5. Efficacies of colistin and tigecycline in mice with experimental pneumonia due to NDM-1-producing strains of Klebsiella pneumoniae and Escherichia coli.

    PubMed

    Docobo-Pérez, Fernando; Nordmann, Patrice; Domínguez-Herrera, Juan; López-Rojas, Rafael; Smani, Younes; Poirel, Laurent; Pachón, Jerónimo

    2012-03-01

    New Delhi metallo-β-lactamase-1 (NDM-1)-producing Enterobacteriaceae have emerged as a global threat. The aim of this study was to assess the efficacies of colistin and tigecycline in an experimental model of pneumonia caused by NDM-1-producing Escherichia coli and Klebsiella pneumoniae. The susceptibilities of K. pneumoniae NDM, E. coli NDM and K. pneumoniae ATCC 29665 were determined using the broth microdilution technique. The pharmacokinetics of colistin and tigecycline in an experimental model of pneumonia were performed using immunocompetent C57BL/6 mice. Mice were treated with colistin (60 mg/kg/day) or tigecycline (10 mg/kg/day). Mortality, bacteraemia and lung bacterial concentrations were recorded. The strains were susceptible to colistin and tigecycline. The ratio of area under the concentration-time curve/minimum inhibitory concentration (AUC/MIC) for colistin was 158.5 (all three strains) and that for tigecycline was 18.5 (K. pneumoniae NDM) and 37 (K. pneumoniae ATCC 29665 and E. coli NDM). In vivo, colistin decreased bacterial lung concentrations of K. pneumoniae NDM and K. pneumoniae ATCC 29665 by 1.16 log colony-forming units (CFU)/g and 2.23 logCFU/g, respectively, compared with controls (not significant). Tigecycline reduced K. pneumoniae NDM and K. pneumoniae ATCC 29665 load by 2.67 logCFU/g and 4.62 logCFU/g (P<0.05). Colistin and tigecycline decreased lung concentrations of E. coli NDM by 2.27 logCFU/g and 4.15 logCFU/g (P<0.05), respectively, compared with controls, and was more active than colistin (P<0.05). In conclusion, these results suggest that colistin is inappropriate for treating pneumonia due to NDM-1-producing K. pneumoniae and its efficacy was suboptimal against NDM-1-producing E. coli. A high tigecycline dose was efficacious for treating experimental pneumonia due to NDM-1-producing E. coli and K. pneumoniae. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  6. Theoretical and Experimental Examination of the Intermediate-Band Concept for Strain-Balanced (In,Ga)As/Ga(As,P) Quantum Dot Solar Cells

    SciTech Connect

    Popescu, V.; Bester, G.; Hanna, M. C.; Norman, A. G.; Zunger, A.

    2008-11-01

    The intermediate-band solar cell (IBSC) concept has been recently proposed to enhance the current gain from the solar spectrum while maintaining a large open-circuit voltage. Its main idea is to introduce a partially occupied intermediate band (IB) between the valence band (VB) and conduction band (CB) of the semiconductor absorber, thereby increasing the photocurrent by the additional VB {yields} IB and IB {yields} CB absorptions. The confined electron levels of self-assembled quantum dots (QDs) were proposed as potential candidates for the implementation of such an IB. Here we report experimental and theoretical investigations on In{sub y}Ga{sub 1-y}As dots in a GaAs{sub 1-x}P{sub x} matrix, examining its suitability for acting as IBSCs. The system has the advantage of allowing strain symmetrization within the structure, thus enabling the growth of a large number of defect-free QD layers, despite the significant size mismatch between the dot material and the surrounding matrix. We examine the various conditions related to the optimum functionality of the IBSC, in particular those connected to the optical and electronic properties of the system. We find that the intensity of absorption between QD-confined electron states and host CB is weak because of their localized-to-delocalized character. Regarding the position of the IB within the matrix band gap, we find that, whereas strain symmetrization can indeed permit growth of multiple dot layers, the current repertoire of GaAs{sub 1-x}P{sub x} barrier materials, as well as In{sub y}Ga{sub 1-y} As dot materials, does not satisfy the ideal energetic locations for the IB. We conclude that other QD systems must be considered for QD-IBSC implementations.

  7. Enterococcus faecalis strains differentially regulate Alix/AIP1 protein expression and ERK 1/2 activation in intestinal epithelial cells in the context of chronic experimental colitis.

    PubMed

    Hoffmann, Micha; Kim, Sandra C; Sartor, R Balfour; Haller, Dirk

    2009-03-01

    Monoassociation of germfree Interleukin 10 gene deficient (IL-10-/-) 129SvEv but not wild-type mice with Enterococcus faecalis induces severe chronic colitis. Bacterial strain-specific effects on the development of chronic intestinal inflammation are not understood. We investigated the molecular mechanisms of E. faecalis OG1RF (human clinical isolate, colitogenic) and E. faecalis ms2 (endogenous isolate from an IL-10-/- mouse) in initiating chronic experimental colitis using IL-10-/- mice. Monoassociation of IL-10-/- mice for 14 weeks revealed significant differences in colonic inflammation (3.6 +/- 0.2 and 2.4 +/- 0.6 for OG1RF and ms2, respectively) (n = 5 mice in each group) (histological scoring (0-4)). Consistent with the tissue pathology, gene expression of the pro-inflammatory chemokine interferon-gamma inducible protein-10 (IP-10) was significantly higher in intestinal epithelial cells (IEC) derived from E. faecalis OG1RF monoassociated IL-10-/- mice. We further compared the differentially E. faecalis induced colitis on the epithelial level by 2D-SDS PAGE coupled with MALDI-TOF MS. Proteome analysis identified 13 proteins which were differentially regulated during disease progression in the epithelium of E. faecalis-monoassociated IL-10-/- mice. Regulation of Alix/AIP1 protein expression and ERK1/2 phosphorylation was validated in primary IEC and epithelial cell lines, suggesting a protective role for Alix/AIP1 in the process of disease progression. Alix/AIP1 protein expression was further characterized in epithelial cell lines using siRNA-mediated knock-down. Our study demonstrates E. faecalis strain-specific induction of colitis in IL-10-/- mice after 14 weeks of monoassociation. Our study suggests that Alix/AIP1 protein expression and ERK1/2 activation are decreased in severe colitis.

  8. Experimental chemotherapy of Schistosoma mansoni with praziquantel and oxamniquine: differential effect of single or combined formulations of drugs on various strains and on both sexes of the parasite.

    PubMed

    Delgado, V S; Suárez, D P; Cesari, I M; Incani, R N

    1992-01-01

    The susceptibility of two Venezuelan (YT and SM) and one Brazilian (BH) strain of Schistosoma mansoni to single oral doses of praziquantel (Pz; 250 or 500 mg/kg), oxamniquine (Ox; 40, 60, or 100 mg/kg) or to low-dose combinations of both drugs (33 mg/kg Pz and 25 mg/kg Ox; 66 mg/kg Pz and 12.5 mg/kg Ox; 250 mg/kg Pz and 40 mg/kg Ox) was experimentally evaluated in mice. At lower doses of either drug, adult worms of the SM isolate were less susceptible than those of the BH and YT isolates. However, no difference in liver or intestinal egg counts (IECs) could be detected among the isolates after this treatment. At such doses, Pz was better than Ox at reducing IECs. In spite of lowered IECs, eggs continued to accumulate in the liver after Ox treatment. At higher individual doses or following treatment with low-dose combinations of both drugs, no difference in susceptibility could be detected among the parasite isolates. Under such conditions, oviposition was drastically reduced in all three isolates. We confirm that Ox preferentially kills male parasites and present for the first time evidence for the preferential killing of female worms by Pz. We propose that the synergistic effect obtained in the present study and in other investigations using low-dose combinations of both drugs may be due to the preferential cytotoxicity of each drug against a different parasite sex.

  9. Isolation, identification and characterization of a novel Rhodococcus sp. strain in biodegradation of tetrahydrofuran and its medium optimization using sequential statistics-based experimental designs.

    PubMed

    Yao, Yanlai; Lv, Zhenmei; Min, Hang; Lv, Zhenhua; Jiao, Huipeng

    2009-06-01

    Statistics-based experimental designs were applied to optimize the culture conditions for tetrahydrofuran (THF) degradation by a newly isolated Rhodococcus sp. YYL that tolerates high THF concentrations. Single factor experiments were undertaken for determining the optimum range of each of four factors (initial pH and concentrations of K(2)HPO(4).3H(2)O, NH(4)Cl and yeast extract) and these factors were subsequently optimized using the response surface methodology. The Plackett-Burman design was used to identify three trace elements (Mg(2+), Zn(2+)and Fe(2+)) that significantly increased the THF degradation rate. The optimum conditions were found to be: 1.80 g/L NH(4)Cl, 0.81 g/L K(2)HPO(4).3H(2)O, 0.06 g/L yeast extract, 0.40 g/L MgSO(4).7H(2)O, 0.006 g/L ZnSO(4).7H(2)O, 0.024 g/L FeSO(4).7H(2)O, and an initial pH of 8.26. Under these optimized conditions, the maximum THF degradation rate increased to 137.60 mg THF h(-1) g dry weight in Rhodococcus sp. YYL, which was nearly five times of that by the previously described THF degrading Rhodococcus strain.

  10. Experimental demonstration of strained Si nanowire GAA n-TFETs and inverter operation with complementary TFET logic at low supply voltages

    NASA Astrophysics Data System (ADS)

    Luong, G. V.; Strangio, S.; Tiedemannn, A.; Lenk, S.; Trellenkamp, S.; Bourdelle, K. K.; Zhao, Q. T.; Mantl, S.

    2016-01-01

    In this work, strained Si (sSi) nanowire array of n-TFETs with gates all around (GAA) yielding ON-currents of 5 μA/μm at a supply voltage Vdd = 0.5 V are presented. Tilted ion implantation with BF2+ into NiSi2 dopant has been used to form a highly doped pocket for the source to channel tunneling junction. These devices indicate sub-threshold slopes (SS) below 60 mV/dec for Id < 10-4 μA/μm at Vds = 0.1 V at room temperature. Common analog device characteristics have been determined at Vdd = 0.5 V resulting in a transconductance gm = 24 μS/μm, transconductance efficiency gm/Id = 23 V-1 and the conductance gd = 0.8 μS/μm normalized to the gate width. Based on the good saturation behavior in the output characteristic, an intrinsic gain of 188 is observed. In addition, we present operation of the first experimental sSi GAA NW C-TFET inverter. In spite of ambipolar behavior, the voltage transfer curves (VTC) indicate wide and constant noise margin levels with steep transitions offering a voltage gain of 25 at Vdd = 1 V.

  11. Experimental and Theoretical Analysis of Strain Engineered Aluminium Nitride on Silicon for High Quality Aluminium(x)Indium(y)Gallium(1-x-y)Nitride Epitaxy

    NASA Astrophysics Data System (ADS)

    Tungare, Mihir

    resembles the experimental substrate engineering process. Finally, crack-free III-N device structures, greater than 3.5 µm in thickness, across an entire 2" Si wafer are developed. The impact of combining our stress dilution technique with conventional strain management techniques on the performance of high electron mobility transistor (HEMT) devices is assessed.

  12. An experimental study and a randomized, double-blind, placebo-controlled clinical trial to evaluate the antisecretory activity of Lactobacillus acidophilus strain LB against nonrotavirus diarrhea.

    PubMed

    Liévin-Le Moal, Vanessa; Sarrazin-Davila, Luis E; Servin, Alain L

    2007-10-01

    Previous studies have shown that selected strains of Lactobacillus have the capacity to antagonize rotavirus-induced diarrhea. However, only a few reports have documented their efficacy against nonrotavirus diarrhea. This study involved an experimental investigation and a clinical trial of the antisecretory activity of Lactobacillus acidophilus strain LB in the context of nonrotavirus diarrhea. The activity of a culture of L. acidophilus LB or of the lyophilized, heat-killed L. acidophilus LB bacteria plus their spent culture medium was tested in inhibiting the formation of fluid-formed domes in cultured human intestinal Caco-2/TC7 cell monolayers infected with diarrheagenic, diffusely adhering Afa/Dr Escherichia coli C1845 bacteria. A randomized, double-blind, placebo-controlled clinical trial of male or female children who were 10 months of age and presented with nonrotavirus, well-established diarrhea was conducted to evaluate the therapeutic efficacy of a pharmaceutical preparation that contains 10 billion heat-killed L. acidophilus LB plus 160 mg of spent culture medium. Infection of the cells with C1845 bacteria that were treated with L. acidophilus LB culture or the lyophilized, heat-killed L. acidophilus LB bacteria plus their culture medium produced a dosage-dependent decrease in the number of fluid-formed domes as compared with cells that were infected with untreated C1845 bacteria. The clinical results show that in selected and controlled homogeneous groups of children with well-established, nonrotavirus diarrhea, adding lyophilized, heat-killed L. acidophilus LB bacteria plus their culture medium to a solution of oral rehydration solution shortened by 1 day the recovery time (ie, the time until the first normal stool was passed) as compared with children who received placebo oral rehydration solution. Heat-killed L. acidophilus LB plus its culture medium antagonizes the C1845-induced increase in paracellular permeability in intestinal Caco-2/TC7 cells

  13. Genomic and Molecular Characterization of Miltefosine Resistance in Leishmania infantum Strains with Either Natural or Acquired Resistance through Experimental Selection of Intracellular Amastigotes

    PubMed Central

    Hendrickx, Sarah; Eberhardt, Eline; Garcia-Hernandez, Raquel; Lachaud, Laurence; Cotton, James; Sanders, Mandy; Cuypers, Bart; Imamura, Hideo; Dujardin, Jean-Claude; Delputte, Peter; Cos, Paul; Caljon, Guy; Gamarro, Francisco; Castanys, Santiago

    2016-01-01

    During the last decade miltefosine (MIL) has been used as first-line treatment for visceral leishmaniasis in endemic areas with antimonial resistance, but a decline in clinical effectiveness is now being reported. While only two MIL-resistant Leishmania infantum strains from HIV co-infected patients have been documented, phenotypic MIL-resistance for L. donovani has not yet been identified in the laboratory. Hence, a better understanding of the factors contributing to increased MIL-treatment failure is necessary. Given the paucity of defined MIL-resistant L. donovani clinical isolates, this study used an experimental amastigote-selected MIL-resistant L. infantum isolate (LEM3323). In-depth exploration of the MIL-resistant phenotype was performed by coupling genomic with phenotypic data to gain insight into gene function and the mutant phenotype. A naturally MIL-resistant L. infantum clinical isolate (LEM5159) was included to compare both datasets. Phenotypically, resistance was evaluated by determining intracellular amastigote susceptibility in vitro and actual MIL-uptake. Genomic analysis provided supportive evidence that the resistance selection model on intracellular amastigotes can be a good proxy for the in vivo field situation since both resistant strains showed mutations in the same inward transporter system responsible for the acquired MIL-resistant phenotype. In line with previous literature findings in promastigotes, our data confirm a defective import machinery through inactivation of the LiMT/LiRos3 protein complex as the main mechanism for MIL-resistance also in intracellular amastigotes. Whole genome sequencing analysis of LEM3323 revealed a 2 base pair deletion in the LiMT gene that led to the formation an early stop codon and a truncation of the LiMT protein. Interestingly, LEM5159 revealed mutations in both the LiMT and LiRos3 genes, resulting in an aberrant expression of the LiMT protein. To verify that these mutations were indeed accountable for

  14. Low-dose benznidazole treatment results in parasite clearance and attenuates heart inflammatory reaction in an experimental model of infection with a highly virulent Trypanosoma cruzi strain.

    PubMed

    Cevey, Ágata Carolina; Mirkin, Gerardo Ariel; Penas, Federico Nicolás; Goren, Nora Beatriz

    2016-04-01

    Chagas disease, caused by Trypanosoma cruzi, is the main cause of dilated cardiomyopathy in the Americas. Antiparasitic treatment mostly relies on benznidazole (Bzl) due to Nifurtimox shortage or unavailability. Both induce adverse drug effects (ADE) of varied severity in many patients, leading to treatment discontinuation or abandonment. Since dosage may influence ADE, we aimed to assess Bzl efficacy in terms of parasiticidal and anti-inflammatory activity, using doses lower than those previously reported. BALB/c mice infected with the T. cruzi RA strain were treated with different doses of Bzl. Parasitaemia, mortality and weight change were assessed. Parasite load, tissue infiltrates and inflammatory mediators were studied in the heart. Serum creatine kinase (CK) activity was determined as a marker of heart damage. The infection-independent anti-inflammatory properties of Bzl were studied in an in vitro model of LPS-treated cardiomyocyte culture. Treatment with 25 mg/kg/day Bzl turned negative the parasitological parameters, induced a significant decrease in IL-1β, IL-6 and NOS2 in the heart and CK activity in serum, to normal levels. No mortality was observed in infected treated mice. Primary cultured cardiomyocytes treated with Bzl showed that inflammatory mediators were reduced via inhibition of the NF-κB pathway. A Bzl dose lower than that previously reported for treatment of experimental Chagas disease exerts adequate antiparasitic and anti-inflammatory effects leading to parasite clearance and tissue healing. This may be relevant to reassess the dose currently used for the treatment of human Chagas disease, aiming to minimize ADE.

  15. Low-dose benznidazole treatment results in parasite clearance and attenuates heart inflammatory reaction in an experimental model of infection with a highly virulent Trypanosoma cruzi strain

    PubMed Central

    Cevey, Ágata Carolina; Mirkin, Gerardo Ariel; Penas, Federico Nicolás; Goren, Nora Beatriz

    2015-01-01

    Chagas disease, caused by Trypanosoma cruzi, is the main cause of dilated cardiomyopathy in the Americas. Antiparasitic treatment mostly relies on benznidazole (Bzl) due to Nifurtimox shortage or unavailability. Both induce adverse drug effects (ADE) of varied severity in many patients, leading to treatment discontinuation or abandonment. Since dosage may influence ADE, we aimed to assess Bzl efficacy in terms of parasiticidal and anti-inflammatory activity, using doses lower than those previously reported. BALB/c mice infected with the T. cruzi RA strain were treated with different doses of Bzl. Parasitaemia, mortality and weight change were assessed. Parasite load, tissue infiltrates and inflammatory mediators were studied in the heart. Serum creatine kinase (CK) activity was determined as a marker of heart damage. The infection-independent anti-inflammatory properties of Bzl were studied in an in vitro model of LPS-treated cardiomyocyte culture. Treatment with 25 mg/kg/day Bzl turned negative the parasitological parameters, induced a significant decrease in IL-1β, IL-6 and NOS2 in the heart and CK activity in serum, to normal levels. No mortality was observed in infected treated mice. Primary cultured cardiomyocytes treated with Bzl showed that inflammatory mediators were reduced via inhibition of the NF-κB pathway. A Bzl dose lower than that previously reported for treatment of experimental Chagas disease exerts adequate antiparasitic and anti-inflammatory effects leading to parasite clearance and tissue healing. This may be relevant to reassess the dose currently used for the treatment of human Chagas disease, aiming to minimize ADE. PMID:26862474

  16. Clinical, virological and serological response of the West African dwarf sheep to experimental infection with different strains of Rift Valley fever virus.

    PubMed

    Tomori, O

    1979-03-01

    West African dwarf sheep were inoculated with three different strains of Rift Valley fever virus (RVFV). Using infective mouse serum as the source of virus classical RVFV disease characterised by sudden onset, a sharp but transient febrile response, viraemia, abortions and the development of specific RVFV antibodies in surviving animals was observed. The severity of clinical response was, however, dependent on the strain of virus used, with animals inoculated with Smithburn's neuroadapted strain showing a milder response than those inoculated with either the Nigerian or Lunyo strain. The inoculation of sheep with RVFV infective mouse brain material of the three different strains resulted in a mild febrile response with low level viraemia. Immune sera from sheep inoculated with both the Nigerian and Smithburn's neurotropic strains did not neutralise the Lunyo virus strain in a mouse intracerebral neutralisation test; the reverse, however, was not the case. The findings indicate that the West African dwarf sheep is highly susceptible to RVFV infection and that previous reports of only a mild clinical response following inoculation with the Nigerian strain were due to infective mouse brain rather than infective mouse serum.

  17. Effects of temperature and strain rate on the deformation of amorphous polyethylene: a comparison between molecular dynamics simulations and experimental results

    NASA Astrophysics Data System (ADS)

    Sahputra, I. H.; Echtermeyer, A. T.

    2013-09-01

    Molecular dynamics simulations are used to investigate the effects of temperature and strain rate on the deformation of amorphous polyethylene. The simulations predict the effects of temperature and strain rate on the stress-strain responses, Young's modulus and Poisson's ratio similar to those observed in laboratory experiments performed by other researchers. The time-temperature superposition principle is applied to the Young's modulus and Poisson's ratio to form a master curve to address the discrepancies in strain rates between the simulations and the experiments. Differences in the numbers of monomers and chains, the degree of crystallinity and molecular orientation lead to discrepancies in the Young's modulus and Poisson's ratio between simulations and experiments.

  18. Mexican Trypanosoma cruzi T. cruzi I strains with different degrees of virulence induce diverse humoral and cellular immune responses in a murine experimental infection model.

    PubMed

    Espinoza, B; Rico, T; Sosa, S; Oaxaca, E; Vizcaino-Castillo, A; Caballero, M L; Martínez, I

    2010-01-01

    It is has been shown that the majority of T. cruzi strains isolated from Mexico belong to the T. cruzi I (TCI). The immune response produced in response to Mexican T. cruzi I strains has not been well characterized. In this study, two Mexican T. cruzi I strains were used to infect Balb/c mice. The Queretaro (TBAR/MX/0000/Queretaro)(Qro) strain resulted in 100% mortality. In contrast, no mortality was observed in mice infected with the Ninoa (MHOM/MX/1994/Ninoa) strain. Both strains produced extended lymphocyte infiltrates in cardiac tissue. Ninoa infection induced a diverse humoral response with a higher variety of immunoglobulin isotypes than were found in Qro-infected mice. Also, a stronger inflammatory TH1 response, represented by IL-12p40, IFNgamma, RANTES, MIG, MIP-1beta, and MCP-1 production was observed in Qro-infected mice when compared with Ninoa-infected mice. We propose that an exacerbated TH1 immune response is a likely cause of pathological damage observed in cardiac tissue and the primary cause of death in Qro-infected mice.

  19. Mexican Trypanosoma cruzi T. cruzi I Strains with Different Degrees of Virulence Induce Diverse Humoral and Cellular Immune Responses in a Murine Experimental Infection Model

    PubMed Central

    Espinoza, B.; Rico, T.; Sosa, S.; Oaxaca, E.; Vizcaino-Castillo, A.; Caballero, M. L.; Martínez, I.

    2010-01-01

    It is has been shown that the majority of T. cruzi strains isolated from Mexico belong to the T. cruzi I (TCI). The immune response produced in response to Mexican T. cruzi I strains has not been well characterized. In this study, two Mexican T. cruzi I strains were used to infect Balb/c mice. The Queretaro (TBAR/MX/0000/Queretaro)(Qro) strain resulted in 100% mortality. In contrast, no mortality was observed in mice infected with the Ninoa (MHOM/MX/1994/Ninoa) strain. Both strains produced extended lymphocyte infiltrates in cardiac tissue. Ninoa infection induced a diverse humoral response with a higher variety of immunoglobulin isotypes than were found in Qro-infected mice. Also, a stronger inflammatory TH1 response, represented by IL-12p40, IFNγ, RANTES, MIG, MIP-1β, and MCP-1 production was observed in Qro-infected mice when compared with Ninoa-infected mice. We propose that an exacerbated TH1 immune response is a likely cause of pathological damage observed in cardiac tissue and the primary cause of death in Qro-infected mice. PMID:20396398

  20. Experimental infection of Haemonchus contortus strains resistant and susceptible to benzimidazoles and the effect on mast cells distribution in the stomach of Mongolian gerbils (Meriones unguiculatus).

    PubMed

    Königová, Alzbeta; Hrckova, Gabriela; Velebný, Samuel; Corba, Július; Várady, Marián

    2008-03-01

    Establishment rate of Haemonchus contortus in non-suppressed and immunosuppressed gerbils within 14 days post-infection was compared after inoculation with 1,000 third-stage larvae (L3), exsheathed BZ-susceptible larvae. Based on significantly higher number of larvae in gerbils receiving low doses of immunosuppressant agent hydrocortisone, development of benzimidazole (BZ)-susceptible and BZ-resistant strain of nematode in the stomach was studied on days 4, 7, 10, and 14 p.i. Sections of stomach from both groups of animals were examined for overall histopathological response and dynamics of mucosal mast cells (MMC) and connective tissue mast cells (CTMC). In the immunosuppressed gerbils, H. contortus L3 stage larvae developed to the L4 stage on days 10 and 14 p.i., and their sex ratio was higher toward female worms. Significantly higher ratios of establishment rate were recorded for BZ-susceptible than BZ-resistant strain. Infection elicited strong inflammation mainly in the lamina propria mucosae, where MMC numbers peaked on day 7 p.i., being present in a significantly higher numbers in gerbils infected with BZ-susceptible strain. Infection with BZ-susceptible strain of nematode also resulted in a higher number of CTMC in comparison with the effect of BZ-resistant strain, which were observed in the tela submucosa only. Thus, H. contortus infection in gerbils seems to be a suitable model to study host-parasite interactions. Our results indicate that BZ-resistant strain of H. contortus have a decreased capacity to establish infection in direct relation with lower mucosal and connective tissue MCs counts in the stomach.

  1. Experimental determination of the velocity and strain rate field in a laminar H2/Air counter-flow diffusion flame via LDA

    NASA Technical Reports Server (NTRS)

    Yeo, S. H.; Dancey, C. L.

    1991-01-01

    Measurements of the axial and radial components of velocity on the air side of stagnation in an axisymmetric H2/Air laminar counter-flow diffusion flame are reported. Results include the two-dimensional velocity field and computed velocity gradients (strain rates) along the stagnation streamline at two 'characteristic' strain rates, below the extinction limit. The measurements generally verify the modeling assumptions appropriate to the model of Kee et al. (1988). The 'traditional' potential flow model is not consistent with the measured results.

  2. Experimental determination of the velocity and strain rate field in a laminar H2/Air counter-flow diffusion flame via LDA

    NASA Technical Reports Server (NTRS)

    Yeo, S. H.; Dancey, C. L.

    1991-01-01

    Measurements of the axial and radial components of velocity on the air side of stagnation in an axisymmetric H2/Air laminar counter-flow diffusion flame are reported. Results include the two-dimensional velocity field and computed velocity gradients (strain rates) along the stagnation streamline at two 'characteristic' strain rates, below the extinction limit. The measurements generally verify the modeling assumptions appropriate to the model of Kee et al. (1988). The 'traditional' potential flow model is not consistent with the measured results.

  3. 3D Experimental Measurement of Lattice Strain and Fracture Behaviour of Sand Particles Using Synchrotron x-ray Diffraction and Tomography

    DOE PAGES

    Cil, M B; Alshibli, Khalid A.; Kenesei, Peter

    2017-09-01

    3D synchrotron X-ray diffraction (3DXRD) and synchrotron micro-computed tomography (SMT) techniques were used to measure and monitor the lattice strain evolution and fracture behavior of natural Ottawa sand particles subjected to 1D compression loading. The particle-averaged lattice strain within sand particles was measured using 3DXRD and then was used to calculate the corresponding lattice stress tensor. In addition, the evolution and mode of fracture of sand particles was investigated using high-resolution 3D SMT images. The results of diffraction data analyses revealed that the major principal component of the lattice strain or stress tensor increased in most of the particles asmore » the global applied compressive load increased until the onset of fracture. Particle fracture and subsequent rearrangements caused significant variation and fluctuations in measured lattice strain/stress values from one particle to another and from one load step to the next one. SMT image analysis at the particle-scale showed that cracks in fractured sand particles generally initiate and propagate along the plane that connects the two contact points. Fractured particles initially split into two or three major fragments followed by disintegration into multiple smaller fragments in some cases. Micro-scale analysis of fractured particles showed that particle position, morphology, the number and location of contact points play a major role in the occurrence of particle fracture in confined comminution of the sand assembly.« less

  4. Experimental evaluation of killed and live Newcastle disease virus vaccines heterologous to the virulent genotype XII challenge strain from the Peru/2008 outbreak

    USDA-ARS?s Scientific Manuscript database

    While all Newcastle disease viruses (NDV) are contained within one serotype and different NDV provide cross-protection against others, antigenically matched strains have been shown to decrease viral shedding. Therefore, using recombinant technology, some companies have directed efforts in developin...

  5. 3D Experimental Measurement of Lattice Strain and Fracture Behavior of Sand Particles Using Synchrotron X-Ray Diffraction and Tomography

    DOE PAGES

    Cil, Mehmet B.; Alshibli, Khalid A.; Kenesei, Peter

    2017-05-27

    3D synchrotron X-ray diffraction (3DXRD) and synchrotron micro-computed tomography (SMT) techniques were used to measure and monitor the lattice strain evolution and fracture behavior of natural Ottawa sand particles subjected to 1D compression loading. The particle-averaged lattice strain within sand particles was measured using 3DXRD and then was used to calculate the corresponding lattice stress tensor. In addition, the evolution and mode of fracture of sand particles was investigated using high-resolution 3D SMT images. The results of diffraction data analyses revealed that the major principal component of the lattice strain or stress tensor increased in most of the particles asmore » the global applied compressive load increased until the onset of fracture. Particle fracture and subsequent rearrangements caused significant variation and fluctuations in measured lattice strain/stress values from one particle to another and from one load step to the next one. SMT image analysis at the particle-scale showed that cracks in fractured sand particles generally initiate and propagate along the plane that connects the two contact points. Fractured particles initially split into two or three major fragments followed by disintegration into multiple smaller fragments in some cases. In conclusion, microscale analysis of fractured particles showed that particle position, morphology, the number and location of contact points play a major role in the occurrence of particle fracture in confined comminution of the sand assembly.« less

  6. A gE-negative bovine herpesvirus 1 vaccine strain is not re-excreted nor transmitted in an experimental cattle population after corticosteroid treatments.

    PubMed

    Mars, M H; de Jong, M C; van Oirschot, J T

    2000-04-03

    To study possible reactivation and to quantify subsequent transmission of a live gE-negative bovine herpesvirus 1 (BHV1) vaccine strain in cattle populations, four experiments were performed. Two groups of cattle were each tested twice for the possibility of reactivation. Inoculation with a gE-negative BHV1 vaccine was done either intramuscularly or intranasally and treatment with corticosteroids in an attempt to reactivate vaccine virus, was done after 6 or 11 weeks, and again after 6 months. To quantify transmission of vaccine virus following possible reactivation, each cattle was housed together with one susceptible contact-cattle. Contact-infections were monitored using virus shedding and antibody responses. After corticosteroid treatments, re-excretion of virus was never detected in cattle that had been inoculated with the gE-negative BHV1 vaccine strain. Contact cattle did not shed gE-negative BHV1, nor mounted any antibody response against BHV1. In contrast, positive control cattle, inoculated intranasally with wild-type BHV1, re-excreted virus in high titers in nasal fluids and transmitted the virus to contact cattle. Based on these results, the transmission ratio R(0) of the vaccine strain was zero. We concluded that it is highly unlikely that the live gE-negative BHV1 vaccine strain will be re-excreted after possible reactivation, and consequently, it is even less likely that reactivated vaccine virus will spread in the cattle population.

  7. Experimental and analytical analysis of stress-strain behavior in a (90/0 deg)2s, SiC/Ti-15-3 laminate

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Melis, Matthew E.; Tong, Mike

    1991-01-01

    The nonlinear stress strain behavior of 90 degree/0 degree sub 2s, SiC/Ti-15-3 composite laminate was numerically investigated with a finite element, unit cell approach. Tensile stress-strain curves from room temperature experiments depicted three distinct regions of deformation, and these regions were predicted by finite element analysis. The first region of behavior, which was linear elastic, occurred at low applied stresses. As applied stresses increased, fiber/matrix debonding in the 90 degree plies caused a break in the stress-strain curve and initiated a second linear region. In this second region, matrix plasticity in the 90 degree plies developed. The third region, which was typified by nonlinear, stress-strain behavior occr red at high stresses. In this region, the onset of matrix plasticity in the 0 degree plies stiffened the laminate in the direction transverse to the applied load. Metallographic sections confirmed the existence of matrix plasticity in specific areas of the structure. Finite element analysis also predicted these locations of matrix slip.

  8. Development and evaluation of an experimental vaccination program using a live avirulent Salmonella typhimurium strain to protect immunized chickens against challenge with homologous and heterologous Salmonella serotypes.

    PubMed Central

    Hassan, J O; Curtiss, R

    1994-01-01

    A stable live avirulent, genetically modified delta cya delta crp Salmonella typhimurium vaccine strain, chi 3985, was used in several vaccination strategies to evaluate its use in the control of Salmonella infection in chickens. Oral vaccination of chickens at 1 and at 14 days of age with 10(8) CFU of chi 3985 protected against invasion of spleen, ovary, and bursa of Fabricius and colonization of the ileum and cecum in chickens challenged with 10(6) CFU of virulent homologous Salmonella strains from group B. Chickens challenged with heterologous Salmonella strains from groups C, D, and E were protected against visceral invasion of spleen and ovary, while invasion of the bursa of Fabricius and colonization of ileum and cecum was reduced in vaccinated chickens. Oral vaccination at 2 and at 4 weeks of age induced an excellent protection against challenge with virulent group B Salmonella serotypes and very good protection against challenge with group D or E Salmonella serotypes, while protection against challenge with group C Salmonella serotypes was marginal but significant. Vaccination at 2 and at 4 weeks of age also protected vaccinated chickens against challenge with 10(8) CFU of highly invasive S. typhimurium or S. enteritidis strains. The protection of chickens vaccinated with chi 3985 against challenge with homologous and heterologous Salmonella serotypes is outstanding, and the complete protection against ovarian invasion in chickens challenged with 10(8) CFU of highly invasive S. typhimurium or S. enteritidis strains suggests that vaccination of chickens with chi 3985 can complement the present hygiene- and sanitation-based Salmonella control measures. This paper reports a breakthrough in the use of live avirulent vaccine to control Salmonella carriers in chickens. PMID:7960134

  9. Colonization of C57BL/6 Mice by a Potential Probiotic Bifidobacterium bifidum Strain under Germ-Free and Specific Pathogen-Free Conditions and during Experimental Colitis

    PubMed Central

    Grimm, Verena; Radulovic, Katarina; Riedel, Christian U.

    2015-01-01

    The effects of at least some probiotics are restricted to live, metabolically active bacteria at their site of action. Colonization of and persistence in the gastrointestinal tract is thus contributing to the beneficial effects of these strains. In the present study, colonization of an anti-inflammatory Bifidobacterium bifidum strain was studied in C57BL/6J mice under germ-free (GF) and specific pathogen-free (SPF) conditions as well as during dextran sulfate sodium (DSS)-induced colitis. B. bifidum S17/pMGC was unable to stably colonize C57BL/6J mice under SPF conditions. Mono-association of GF mice by three doses on consecutive days led to long-term, stable detection of up to 109 colony forming units (CFU) of B. bifidum S17/pMGC per g feces. This stable population was rapidly outcompeted upon transfer of mono-associated animals to SPF conditions. A B. animalis strain was isolated from the microbiota of these re-conventionalized mice. This B. animalis strain displayed significantly higher adhesion to murine CMT–93 intestinal epithelial cells (IECs) than to human Caco–2 IECs (p = 0.018). Conversely, B. bifidum S17/pMGC, i.e., a strain of human origin, adhered at significantly higher levels to human compared to murine IECs (p < 0.001). Disturbance of the gut ecology and induction of colitis by DSS-treatment did not promote colonization of the murine gastrointestinal tract (GIT) by B. bifidum S17/pMGC. Despite its poor colonization of the mouse GIT, B. bifidum S17/pMGC displayed a protective effect on DSS-induced colitis when administered as viable bacteria but not as UV-inactivated preparation. Collectively, these results suggest a selective disadvantage of B. bifidum S17/pMGC in the competition with the normal murine microbiota and an anti-inflammatory effect that requires live, metabolically active bacteria. PMID:26439388

  10. Colonization of C57BL/6 Mice by a Potential Probiotic Bifidobacterium bifidum Strain under Germ-Free and Specific Pathogen-Free Conditions and during Experimental Colitis.

    PubMed

    Grimm, Verena; Radulovic, Katarina; Riedel, Christian U

    2015-01-01

    The effects of at least some probiotics are restricted to live, metabolically active bacteria at their site of action. Colonization of and persistence in the gastrointestinal tract is thus contributing to the beneficial effects of these strains. In the present study, colonization of an anti-inflammatory Bifidobacterium bifidum strain was studied in C57BL/6J mice under germ-free (GF) and specific pathogen-free (SPF) conditions as well as during dextran sulfate sodium (DSS)-induced colitis. B. bifidum S17/pMGC was unable to stably colonize C57BL/6J mice under SPF conditions. Mono-association of GF mice by three doses on consecutive days led to long-term, stable detection of up to 109 colony forming units (CFU) of B. bifidum S17/pMGC per g feces. This stable population was rapidly outcompeted upon transfer of mono-associated animals to SPF conditions. A B. animalis strain was isolated from the microbiota of these re-conventionalized mice. This B. animalis strain displayed significantly higher adhesion to murine CMT-93 intestinal epithelial cells (IECs) than to human Caco-2 IECs (p = 0.018). Conversely, B. bifidum S17/pMGC, i.e., a strain of human origin, adhered at significantly higher levels to human compared to murine IECs (p < 0.001). Disturbance of the gut ecology and induction of colitis by DSS-treatment did not promote colonization of the murine gastrointestinal tract (GIT) by B. bifidum S17/pMGC. Despite its poor colonization of the mouse GIT, B. bifidum S17/pMGC displayed a protective effect on DSS-induced colitis when administered as viable bacteria but not as UV-inactivated preparation. Collectively, these results suggest a selective disadvantage of B. bifidum S17/pMGC in the competition with the normal murine microbiota and an anti-inflammatory effect that requires live, metabolically active bacteria.

  11. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  12. Sandstone compaction under actively controlled uniaxial strain conditions - an experimental study on the causes of subsidence in the Dutch Wadden Area

    NASA Astrophysics Data System (ADS)

    Hol, Sander; Mossop, Antony; van der Linden, Arjan; Zuiderwijk, Pedro; Makurat, Axel; van Eijs, Rob

    2016-04-01

    In the Wadden Sea, a tidal-flat area located between the North Sea and the Dutch mainland shore, and UNESCO World Heritage site, subsidence could potentially impact the ecological system. To guide the licensing process governing gas extraction for the area by a solid understanding of the system's response to production, Nederlandse Aardolie Maatschappij (NAM) has carried out a study on the magnitudes, timing, and mechanisms of subsidence related to gas production. As part of this study program, we address the effect of production-induced reservoir compaction, using core samples from the Moddergat field located at the Wadden Sea coastline, from a depth of ~3800 m TVDSS, to assess the nature of the compaction mechanisms that operate. In this contribution, we focus on the uniaxial strain response of Permian, Aeolian sandstone to pore pressure depletion. As the majority of experiments reported in the literature are conducted under triaxial stress conditions, this data set is somewhat unique, and can help confirm the validity of micromechanical processes found for triaxial stress conditions. We report over 30 data sets of experiments carried out using 1.0 and 1.5 inch diameter plugs, sub-sampled from the extracted sandstone core material. The experiments start at in-situ conditions of pore pressure (Pf=~57 MPa), stress (Sv=~80 MPa, Sh=~67 MPa) and temperature (T up to 100 °C), and deplete to a pore pressure of 3 MPa, under actively controlled lateral constraint boundary conditions (i.e. uniaxial strain). Care was taken to systematically vary porosity and sample morphology to ensure representation of the intra-reservoir variability. Our laboratory data show that pressure-depletion results in a strain in the range of 5·10-3-1·10-2 over the total duration of the experiments of 5-12 weeks, with approximately 80% of the total strain response being close to instantaneous, and 20% developing over time. The total strain response develops during depletion as a result of

  13. Comparative genomics and experimental evolution of Escherichia coli BL21(DE3) strains reveal the landscape of toxicity escape from membrane protein overproduction

    PubMed Central

    Kwon, Soon-Kyeong; Kim, Seong Keun; Lee, Dae-Hee; Kim, Jihyun F.

    2015-01-01

    Achieving sufficient yields of proteins in their functional form represents the first bottleneck in contemporary bioscience and biotechnology. To accomplish successful overexpression of membrane proteins in a workhorse organism such as E. coli, defined and rational optimization strategies based on an understanding of the genetic background of the toxicity-escape mechanism are desirable. To this end, we sequenced the genomes of E. coli C41(DE3) and its derivative C43(DE3), which were developed for membrane protein production. Comparative analysis of their genomes with those of their ancestral strain E. coli BL21(DE3) revealed various genetic changes in both strains. A series of E. coli variants that are able to tolerate transformation with or overexpression of membrane proteins were generated by in vitro evolution. Targeted sequencing of the evolved strains revealed the mutational hotspots among the acquired genetic changes. By these combinatorial approaches, we found non-synonymous changes in the lac repressor gene of the lac operon as well as nucleotide substitutions in the lacUV5 promoter of the DE3 region, by which the toxic effect to the host caused by overexpression of membrane proteins could be relieved. A mutation in lacI was demonstrated to be crucial for conferring tolerance to membrane protein overexpression. PMID:26531007

  14. Comparative genomics and experimental evolution of Escherichia coli BL21(DE3) strains reveal the landscape of toxicity escape from membrane protein overproduction.

    PubMed

    Kwon, Soon-Kyeong; Kim, Seong Keun; Lee, Dae-Hee; Kim, Jihyun F

    2015-11-04

    Achieving sufficient yields of proteins in their functional form represents the first bottleneck in contemporary bioscience and biotechnology. To accomplish successful overexpression of membrane proteins in a workhorse organism such as E. coli, defined and rational optimization strategies based on an understanding of the genetic background of the toxicity-escape mechanism are desirable. To this end, we sequenced the genomes of E. coli C41(DE3) and its derivative C43(DE3), which were developed for membrane protein production. Comparative analysis of their genomes with those of their ancestral strain E. coli BL21(DE3) revealed various genetic changes in both strains. A series of E. coli variants that are able to tolerate transformation with or overexpression of membrane proteins were generated by in vitro evolution. Targeted sequencing of the evolved strains revealed the mutational hotspots among the acquired genetic changes. By these combinatorial approaches, we found non-synonymous changes in the lac repressor gene of the lac operon as well as nucleotide substitutions in the lacUV5 promoter of the DE3 region, by which the toxic effect to the host caused by overexpression of membrane proteins could be relieved. A mutation in lacI was demonstrated to be crucial for conferring tolerance to membrane protein overexpression.

  15. Real Time Three-Dimensional Echocardiographic Evaluations of Fetal Left Ventricular Stroke Volume, Mass, and Myocardial Strain: In Vitro and In Vivo Experimental Study.

    PubMed

    Zhu, Meihua; Ashraf, Muhammad; Zhang, Zhijun; Streiff, Cole; Shimada, Eriko; Kimura, Sumito; Schaller, Traci; Song, Xubo; Sahn, David J

    2015-11-01

    Left ventricular stroke volume, mass, and myocardial strain are valuable indicators of fetal heart function. This study investigated the feasibility of nongated real time three-dimensional echocardiography (RT3DE) to determine fetal stroke volume (SV), left ventricular mass (LVM), and myocardial strain under different conditions. To evaluate fetal hearts, fetal-sized rabbit hearts were used in this study. The in vitro portion of this study was carried out using a balloon inserted into the LV of eight fresh rabbit hearts and driven by a calibrated pulsatile pump. RT3DE volumes were obtained at various pump-set SVs. The in vivo experiments in this study were performed on open-chest rabbits. RT3DE volumes were acquired at the following conditions: baseline, simulated hypervolemia, inferior vena cava (IVC) ligation, and ascending aorta (AAO) ligation. Displacement values and sonomicrometry data were used as references for RT3DE-derived SV, LVM, longitudinal strain (LS), and circumferential strain (CS). Excellent correlations between RT3DE-derived values and reference values were demonstrated and accompanied by high coefficients of determination (R(2) ) for both in vitro and in vivo studies for SV, LVM, LS, and CS (in vitro: SV: R(2)  = 0.98; LVM: R(2)  = 0.97; LS: R(2)  = 0.87, CS: R(2)  = 0.80; in vivo: SV: R(2)  = 0.92; LVM: R(2)  = 0.98; LS: in vivo: R(2)  = 0.84; CS: in vivo: R(2)  = 0.76; all P < 0.05). RT3DE is capable of quantifying the SV, LVM, and myocardial strain of fetal-sized hearts under different conditions. This nongated RT3DE may aid the evaluation of fetal cardiac function, providing a superior understanding of the progress of fetal heart disorders. © 2015, Wiley Periodicals, Inc.

  16. Experimental study and mathematical modeling of the behavior of St.3, 20Kh13, and 08Kh18N10T steels in wide ranges of strain rates and temperatures

    NASA Astrophysics Data System (ADS)

    Bragov, A. M.; Igumnov, L. A.; Kaidalov, V. B.; Konstantinov, A. Yu.; Lapshin, D. A.; Lomunov, A. K.; Mitenkov, F. M.

    2015-11-01

    Results of an experimental study of the behavior of St.3, 20Kh13, and 08Kh18N10T steels under static and dynamic loading are reported. The influence of the strain rate and temperature on characteristics of strength and plasticity is studied. Based on the data obtained, the parameters of the Johnson-Cook model are determined. This model is used in commercial software to describe the yield surface radius as a function of loading parameters. The adequacy of the identified model is verified in a series of special test experiments.

  17. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  18. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGES

    Song, Bo; Yao, Shurong; Nie, Xu; ...

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  19. On the origin of residual strain in shape memory alloys: experimental investigation on evolutions in the microstructure of CuAlBe during complex thermomechanical loadings

    NASA Astrophysics Data System (ADS)

    Barati, M.; Arbab Chirani, S.; Kadkhodaei, M.; Saint-Sulpice, L.; Calloch, S.

    2017-02-01

    The behaviors of shape memory alloys (SMAs) strongly depend on the presence of different phases: austenite, thermally-induced martensite and stress-induced martensite. Consequently, it is important to know the phase volume fraction of each phases and their evolution during thermomechanical loadings. In this work, a three-phase proportioning method based on electric resistivity variation of a CuAlBe SMA is proposed. Simple thermomechanical loadings (i. e. pseudoplasticity and pseudoelasticity), one-way shape memory effect, recovery stress, assisted two-way memory effect at different level of stress and cyclic pseudoelasticity tests are investigated. Based on the electric resistivity results, during each loading path, evolution of the microstructure is determined. The origin of residual strain observed during the considered thermomechanical loadings is discussed. A special attention is paid to two-way shape memory effect generated after considered cyclic loadings and its relation with the developed residual strain. These results permit to identify and to validate the macroscopic models of SMAs behaviors.

  20. Fulminant Cryptosporidiosis after Near-Drowning: a Human Cryptosporidium parvum Strain Implicated in Invasive Gastrointestinal Adenocarcinoma and Cholangiocarcinoma in an Experimental Model

    PubMed Central

    Benamrouz, Sadia; Guyot, Karine; Mouray, Anthony; Chassat, Thierry; Flament, Nicolas; Delhaes, Laurence; Coiteux, Valerie; Delaire, Baptiste; Praet, Marleen; Cuvelier, Claude; Gosset, Pierre; Dei-Cas, Eduardo; Creusy, Colette

    2012-01-01

    In the present work, we report the characterization of a Cryptosporidium parvum strain isolated from a patient who nearly drowned in the Deule River (Lille, France) after being discharged from the hospital where he had undergone allogeneic stem cell transplantation. After being rescued and readmitted to the hospital, he developed fulminant cryptosporidiosis. The strain isolated from the patient's stools was identified as C. parvum II2A15G2R1 (subtype linked to zoonotic exposure) and inoculated into SCID mice. In this host, this virulent C. parvum isolate induced not only severe infection but also invasive gastrointestinal and biliary adenocarcinoma. The observation of adenocarcinomas that progressed through all layers of the digestive tract to the subserosa and spread via blood vessels confirmed the invasive nature of the neoplastic process. These results indicate for the first time that a human-derived C. parvum isolate is able to induce digestive cancer. This study is of special interest considering the exposure of a large number of humans and animals to this waterborne protozoan, which is highly tumorigenic when inoculated in a rodent model. PMID:22247151

  1. Experimental infections of different carp strains with the carp edema virus (CEV) give insights into the infection biology of the virus and indicate possible solutions to problems caused by koi sleepy disease (KSD) in carp aquaculture.

    PubMed

    Adamek, Mikolaj; Oschilewski, Anna; Wohlsein, Peter; Jung-Schroers, Verena; Teitge, Felix; Dawson, Andy; Gela, David; Piackova, Veronika; Kocour, Martin; Adamek, Jerzy; Bergmann, Sven M; Steinhagen, Dieter

    2017-02-21

    Outbreaks of koi sleepy disease (KSD) caused by carp edema virus (CEV) may seriously affect populations of farmed common carp, one of the most important fish species for global food production. The present study shows further evidence for the involvement of CEV in outbreaks of KSD among carp and koi populations: in a series of infection experiments, CEV from two different genogroups could be transmitted to several strains of naïve common carp via cohabitation with fish infected with CEV. In recipient fish, clinical signs of KSD were induced. The virus load and viral gene expression results confirm gills as the target organ for CEV replication. Gill explants also allowed for a limited virus replication in vitro. The in vivo infection experiments revealed differences in the virulence of the two CEV genogroups which were associated with infections in koi or in common carp, with higher virulence towards the same fish variety as the donor fish. When the susceptibility of different carp strains to a CEV infection and the development of KSD were experimentally investigated, Amur wild carp showed to be relatively more resistant to the infection and did not develop clinical signs for KSD. However, the resistance could not be related to a higher magnitude of type I IFN responses of affected tissues. Despite not having a mechanistic explanation for the resistance of Amur wild carp to KSD, we recommend using this carp strain in breeding programs to limit potential losses caused by CEV in aquaculture.

  2. Immune responses and protection against experimental challenge after vaccination of bison with Brucella abortus strains RB51 or RB51 overexpressing superoxide dismutase and Glycosyltransferase genes

    USDA-ARS?s Scientific Manuscript database

    Vaccination is a tool that could be beneficial in managing the high prevalence of brucellosis in free-ranging bison in Yellowstone National Park. In this study, we characterized immunologic responses and protection against experimental challenge after vaccination of bison with Brucella abortus stra...

  3. Background Strain and the Differential Susceptibility of Podocyte-Specific Deletion of Myh9 on Murine Models of Experimental Glomerulosclerosis and HIV Nephropathy

    PubMed Central

    Johnstone, Duncan B.; Ikizler, Omer; Zhang, Jidong; Holzman, Lawrence B.

    2013-01-01

    We previously reported that podocyte-specific deletion of Myh9 (conventional myosin heavy chain 2A) in C57BL/6 mice does not cause spontaneous kidney disease but instead results in a predisposition to glomerulosclerosis in response to a second model of glomerular injury. In contrast, other investigators reported that podocyte-specific deletion of Myh9 (PodΔMyh9) resulted in spontaneous glomerulosclerosis in mice on a mixed background, suggesting that the glomerulosclerosis is dependent on background strain. In order to elucidate the cause of this strain dependent effect Podocin::Cre and Myh9flox alleles were backcrossed to mouse strain FVB/N, which is highly susceptible to glomerulosclerosis, with the aim of intercrossing susceptible FVB/N and resistant C57BL/6 mice in subsequent congenic analyses. However, after backcrossing mice to FVB/N and aging mice to 28 weeks, we found no evidence of glomerular disease in PodΔMyh9 mice vs control littermates (urine MAC ratio all p>0.05). We also tested C57BL/6 PodΔMyh9 mice for a predisposition to injury from models other than Adriamycin including HIV nephropathy (HIVAN), puromycin nephropathy, and sheep nephrotoxic serum. In the Tg26 model of HIVAN, we found that podocyte-specific deletion of Myh9 resulted in a modest hypersensitivity in adults compared to Tg26+ control littermates (urine MAC ratio, p<0.05 or less). In contrast, we found that PodΔMyh9 mice were not predisposed to injury in response to other injury models including puromycin nephropathy and sheep nephrotoxic serum. While the mechanism of injury in these models is not fully understood, we conclude that PodΔMyh9 results in a variable susceptibility to glomerulosclerosis in response to different models of glomerular injury. In addition, based on the lack of a spontaneous phenotype of glomerulosclerosis in both C57BL/6 and FVB/N mice, we propose that Myh9 is not absolutely required in adult podocytes. PMID:23874454

  4. Insecticidal and sterilizing effect of Olyset Duo®, a permethrin and pyriproxyfen mixture net against pyrethroid-susceptible and -resistant strains of Anopheles gambiae s.s.: a release-recapture assay in experimental huts

    PubMed Central

    Djènontin, Armel; Ahoua Alou, Ludovic P.; Koffi, Alphonsine; Zogo, Barnabas; Duarte, Elves; N’Guessan, Raphael; Moiroux, Nicolas; Pennetier, Cédric

    2015-01-01

    In the context of the widespread distribution of pyrethroid resistance among malaria vectors, we did a release-recapture trial in experimental huts to investigate the insecticidal and sterilizing effects of a novel long-lasting net (LN), Olyset® Duo, incorporating a mixture of permethrin (PER) and the insect growth regulator (IGR), pyri-proxyfen (PPF). An LN containing PPF alone and a classic Olyset® Net were tested in parallel as positive controls. The effect of progressive number of holes (6, 30, or 150) that may accrue in nets over time was simulated. We used two laboratory Anopheles gambiae s.s. strains: the susceptible Kisumu strain and the pyrethroid-resistant VK-Per strain having solely kdr as resistance mechanism. The effect of these nets on the reproductive success of blood-fed females that survived the different LNs conditions was recorded. Regardless of the mosquito strain, the LNs containing PPF alone with as many as 30 holes drastically reduced the number of eggs laid by females succeeding in feeding, i.e. fecundity by 98% and egg hatching rate (fertility) by 93% relative to untreated control net. Very few of the resistant females blood fed and survived under the Olyset® Duo with similar number of holes (up to 30) but of these few, the inhibition of reproductive success was 100%. There was no evidence that the Olyset® Duo LN with 150 holes impacted fecundity or fertility of the resistant colony. The efficacy of Olyset® Duo is encouraging and clearly illustrates that this new net might be a promising tool for malaria transmission control and resistance management. PMID:26489479

  5. Patterns of cellular immunity associated with experimental infection with rDEN2Δ30 (Tonga/74) supports its suitability as a human DENV challenge strain.

    PubMed

    Grifoni, Alba; Angelo, Michael; Sidney, John; Paul, Sinu; Peters, Bjoern; de Silva, Aruna D; Phillips, Elizabeth; Mallal, Simon; Diehl, Sean A; Botten, Jason; Boyson, Jonathan; Kirkpatrick, Beth D; Whitehead, Stephen S; Durbin, Anna P; Sette, Alessandro; Weiskopf, Daniela

    2017-02-01

    A deletion variant of the DENV2 Tonga/74 strain lacking 30 nucleotides from its 3' untranslated region (rDEN2Δ30) has previously been established for use in a controlled DENV human challenge model. To evaluate if this model is appropriate to derive correlates of protection for DENV vaccines based on cellular immunity, we wanted to compare how the cellular immune response to this challenge strain compares to the response induced by natural infection. To achieve this, we predicted HLA class I and class II restricted peptides from rDEN2Δ30 and used them, in an IFN-gamma ELISPOT assay, to interrogate CD8(+) and CD4(+) T cell responses in healthy volunteers infected with rDEN2Δ30. At the level of CD8 responses, vigorous ex vivo responses were detected in approximately 80% of donors. These responses were similar in terms of magnitude and numbers of epitopes recognized to previously reported responses observed in PBMC from donors from DENV hyper-endemic regions. The similarity extended to the immunodominance hierarchy of the DENV nonstructural proteins NS3, NS5, and NS1 being dominant in both donor cohorts. At the CD4 level, responses were less vigorous compared to natural DENV infection, and were more focused on nonstructural proteins. The epitopes recognized following rDEN2Δ30 infection and natural infection were largely overlapping for both CD8 (100%) and CD4 (85%) responses. Finally, rDEN2Δ30 induced stronger CD8 responses compared to other more attenuated DENV isolates.

  6. Strain and magnetic remanence

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1993-05-01

    Experimental data may be compatible with the hypothesis that a single direction of magnetic remanence rotates as a rigid marker with strains up to 40% shortening in coaxial, perfect flattening ( X = Y > Z). Detailed agreement with the passive line model is relatively poor for the specimens in which remanance is carried by magnetite. However, for this range of strains the differences with the passive line model (Wettstein's equation) are so slight that the latter model may be more easily employed to de-strain or restore deformed remanance to its original attitude. In the case of hematite-bearing remanences, the differences between the passive line and rigid marker model are even smaller because of the higher aspect ratios of grains of hematite. Therefore it is suggested that Wettstein's equation may be safely used to restore remanence after even higher strains, where the remanence is carried by hematite.

  7. Nanowires enabling strained photovoltaics

    SciTech Connect

    Greil, J.; Bertagnolli, E.; Lugstein, A.; Birner, S.

    2014-04-21

    Photovoltaic nano-devices have largely been relying on charge separation in conventional p-n junctions. Junction formation via doping, however, imposes major challenges in process control. Here, we report on a concept for photovoltaic energy conversion at the nano scale without the need for intentional doping. Our approach relies on charge carrier separation in inhomogeneously strained germanium nanowires (Ge NWs). This concept utilizes the strain-induced gradient in bandgap along tapered NWs. Experimental data confirms the feasibility of strain-induced charge separation in individual vapor-liquid-solid grown Ge NW devices with an internal quantum efficiency of ∼5%. The charge separation mechanism, though, is not inherently limited to a distinct material. Our work establishes a class of photovoltaic nano-devices with its opto-electronic properties engineered by size, shape, and applied strain.

  8. Effects of extracts from Echinacea purpurea (L) MOENCH on mice infected with different strains of Toxoplasma gondii.

    PubMed

    Gasparotto Junior, Arquimedes; Cosmo, Maria Luiza Antonio; Reis, Michelle de Paula; Dos Santos, Pamela Secundo; Gonçalves, Daniela Dib; Gasparotto, Francielly Mourão; Navarro, Italmar Teodorico; Lourenço, Emerson Luiz Botelho

    2016-10-01

    In recent years, due to the growing concern about recurrent epidemics by Toxoplasma gondii and other pathogens in Brazil, there has been an increase in the use of different preparations obtained from Echinacea purpurea in order to test their effectiveness against these infections. Although studies have suggested the beneficial effects of this species against the influenza virus, no data are available on the use of E. purpurea aqueous extract in T. gondii infections. Thus, the aim of this study was to analyze the effect of its administration in Swiss mice submitted to acute and prolonged infection with different T. gondii strains. This study showed that E. purpurea extract induced a significant reduction in the number of tachyzoites in the peritoneal fluid and liver imprints from mice infected by the RH strain. Moreover, prolonged treatment significantly increased the number of brain cysts of animals infected with ME 49 strain. The results obtained in this study suggest that the crude extract obtained from E. purpurea has important protective activities against infection with different T. gondii strains.

  9. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  10. Escherichia coli strain Nissle 1917 ameliorates experimental colitis by modulating intestinal permeability, the inflammatory response and clinical signs in a faecal transplantation model.

    PubMed

    Souza, Éricka L; Elian, Samir D; Paula, Laís M; Garcia, Cristiana C; Vieira, Angélica T; Teixeira, Mauro M; Arantes, Rosa M; Nicoli, Jacques R; Martins, Flaviano S

    2016-03-01

    Inflammatory bowel diseases (IBDs) are a group of inflammatory conditions of the gut that include ulcerative colitis and Crohn's disease. Probiotics are live micro-organisms that may be used as adjuvant therapy for patients with IBD. The aim of this study was to evaluate the effect of prophylactic ingestion of Escherichia coli strain Nissle 1917 (EcN) in a murine model of colitis. For induction of colitis, mice were given a 3.5% dextran sodium sulfate (DSS) solution for 7 days in drinking water. EcN administration to mice subjected to DSS-induced colitis resulted in significant reduction in clinical and histopathological signs of disease and preservation of intestinal permeability. We observed reduced inflammation, as assessed by reduced levels of neutrophils, eosinophils, chemokines and cytokines. We observed an increase in the number of regulatory T-cells in Peyer's patches. Germ-free mice received faecal content from control or EcN-treated mice and were then subjected to DSS-induced colitis. We observed protection from colitis in animals that were colonized with faecal content from EcN-treated mice. These results suggest that preventative oral administration of EcN or faecal microbiota transplantation with EcN-containing microbiota ameliorates DSS-induced colitis by modifying inflammatory responsiveness to DSS.

  11. Evaluation of four DNA extraction protocols for Brucella abortus detection by PCR in tissues from experimentally infected cows with the 2308 strain.

    PubMed

    Vejarano, M P; Matrone, M; Keid, L B; Rocha, V C M; Ikuta, C Y; Rodriguez, C A R; Salgado, V R; Ferreira, F; Dias, R A; Telles, E O; Ferreira Neto, J S

    2013-04-01

    This study compared 4 protocols for DNA extraction from homogenates of 6 different organs of cows infected with the Brucella abortus 2308 strain. The extraction protocols compared were as follows: GT (guanidine isothiocyanate lysis), Boom (GT lysis with the carrying suspension diatomaceous earth), PK (proteinase K lysis), and Santos (lysis by boiling and freezing with liquid nitrogen). Positive and negative gold standard reference groups were generated by classical bacteriological methods. All samples were processed with the 4 DNA extraction protocols and amplified with the B4 and B5 primers. The number of positive samples in the placental cotyledons was higher than that in the other organs. The cumulated results showed that the Santos protocol was more sensitive than the Boom (p=0.003) and GT (p=0.0506) methods and was similar to the PK method (p=0.2969). All of the DNA extraction protocols resulted in false-negative results for PCR. In conclusion, despite the disadvantages of classical bacteriological methods, the best approach for direct diagnosis of B. abortus in organs of infected cows includes the isolation associated with PCR of DNA extracted from the cotyledon by the Santos or PK methods.

  12. Establishment, in silico analysis, and experimental verification of a large-scale metabolic network of the xanthan producing Xanthomonas campestris pv. campestris strain B100.

    PubMed

    Schatschneider, Sarah; Persicke, Marcus; Watt, Steven Alexander; Hublik, Gerd; Pühler, Alfred; Niehaus, Karsten; Vorhölter, Frank-Jörg

    2013-08-20

    The γ-proteobacterium Xanthomonas campestris pv. campestris (Xcc) B100 synthesizes the polysaccharide xanthan, a commercially important viscosifier. Since the complete genome of Xcc B100 is available, systems biology tools were applied to obtain a deeper understanding of the metabolism involved in xanthan biosynthesis. A large-scale metabolic network was reconstructed and manually curated. The reconstructed network included 352 genes, 437 biochemical reactions, 10 transport reactions, and 338 internal metabolites. To use this network for flux balance analysis, the biomass composition of Xcc B100 was determined. The comprehensive model obtained was applied for in silico analyses to predict biomass generation and gene essentiality. Predictions were extensively validated by analyzing batch culture performance and by carbon balancing including xanthan production. Single gene deletion mutants causing deficiencies in the central carbohydrate metabolism were constructed to enforce major flux redistributions. The impact of xanthan production was studied in vivo and in silico, comparing the physiology of a gumD mutant, negative in xanthan production, with the original strain. The results indicate a redistribution of resources from xanthan to biomass, rather than a reduction in carbon uptake. With this high quality metabolic model, both systems biology analyses and synthetic biology reengineering of Xcc gained an important tool.

  13. Symmetry in strain engineering of nanomembranes: making new strained materials.

    PubMed

    Paskiewicz, Deborah M; Scott, Shelley A; Savage, Donald E; Celler, George K; Lagally, Max G

    2011-07-26

    Strain in a material changes the lattice constant and thereby creates a material with new properties relative to the unstrained, but chemically identical, material. The ability to alter the strain (its magnitude, direction, extent, periodicity, symmetry, and nature) allows tunability of these new properties. A recent development, crystalline nanomembranes, offers a powerful platform for using and tuning strain to create materials that have unique properties, not achievable in bulk materials or with conventional processes. Nanomembranes, because of their thinness, enable elastic strain sharing, a process that introduces large amounts of strain and unique strain distributions in single-crystal materials, without exposing the material to the formation of extended defects. We provide here prescriptions for making new strained materials using crystal symmetry as the driver: we calculate the strain distributions in flat nanomembranes for two-fold and four-fold elastically symmetric materials. We show that we can controllably tune the amount of strain and the asymmetry of the strain distribution in elastically isotropic and anisotropic materials uniformly over large areas. We perform the experimental demonstration with a trilayer Si(110)/Si((1-x))Ge(x)(110)/Si(110) nanomembrane: an elastically two-fold symmetric system in which we can transfer strain that is biaxially isotropic. We are thus able to make uniformly strained materials that cannot be made any other way.

  14. Deformation mechanisms and resealing of damage zones in experimentally deformed cemented and un-cemented clay-rich geomaterials, at low bulk strain

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Urai, Janos L.; Schuck, Bernhardt; Hoehne, Nadine; Oelker, Anne; Bésuelle, Pierre; Viggiani, Gioacchino; Schmatz, Joyce; Klaver, Jop

    2017-04-01

    A microphysics-based understanding of mechanical and fluid flow properties in clay-rich geomaterials is required for extrapolating better constitutive equations beyond the laboratory's time scales, so that predictions over the long term can be made less uncertain. In this contribution, we present microstructural investigations of rocks specimens sheared in triaxial compression at low bulk strain, by using the combination of broad-ion-beam (BIB) milling and scanning electron microscopy (SEM) to infer deformation mechanisms based on microstructures imaged at sub-micron resolution. Two end-member clay-rich geomaterials from European Underground Laboratories (URL) were analysed: (i) the poorly cemented Boom Clay sediment (BC from URL at Mol/Dessel, Belgium; confining pressure [CP] = 0.375 & 1.5 MPa) and (ii) the Callovo-Oxfordian claystone (COx from the URL at Bure, France; CP = 2 & 10 MPa). Although as a first approximation the inelastic bahvior of cemented and uncemented clay-rich geomaterials can be described by similar pressure-dependent hardening plasticity models, deformed samples in this contribution show very contrasting micro-scale behaviour: microstructures reveal brittle-ductile transitional behaviour in BC, whereas deformation in COx is dominantly cataclastic. In Boom Clay, at meso-scale, shear bands exhibit characteristics that are typical of uncemented small-grained clay-rich materials deformed at high shear strains, consisting of anastomosing shears interpreted as Y- and B-shears, which bound the passively deformed microlithons. At micro- down to nano-scale, the strong shape preferential orientation of clay aggregates in the anastomosing shears is interpreted to be responsible of the shear weakness. More over, the reworking of clay aggregates during deformation contributes to the collapsing of porosity in the shear band. Ductile deformation mechanisms represented by grain-rotation, grain-sliding, bending and granular flow mechanisms are strongly involved

  15. Experimental Infection of Ornithodoros erraticus sensu stricto with Two Portuguese African Swine Fever Virus Strains. Study of Factors Involved in the Dynamics of Infection in Ticks.

    PubMed

    Ribeiro, Rita; Otte, Joachim; Madeira, Sara; Hutchings, Geoff H; Boinas, Fernando

    2015-01-01

    African swine fever (ASF) is a frequently devastating hemorrhagic disease of domestic pigs and wild boar and Ornithodoros erraticus sensu stricto argasid ticks are the only biological vectors of African swine fever virus (ASFV) known to occur in Europe. Recently this disease emerged in Eastern Europe and Russian Federation, showing a huge potential for a rapid spread between countries. There is some risk of re-emergence of ASF in the countries where these ticks exist, that can contribute for the persistence of infection and compromise control measures. In this study we aimed to identify factors that determine the probability of infection and its dynamics in the tick vector Ornithodoros erraticus sensu stricto, with two Portuguese strains of ASFV. Our results suggest that these ticks have a high likelihood of excreting the two haemadsorbing ASF viruses of different host origins and that, in field surveys, the analysis of adults and 5th nymphal stage can provide the best chance of detecting virus infection. The results also indicate that infection of pigs with highly virulent ASF viruses will promote higher rates of infection and a higher likelihood for virus excretion by ticks. Nevertheless, there is also a risk, although lower, that ticks can become infected on pigs that have overcome the acute phase of infection, which was simulated in our study by membrane feeding ticks with low titres of virus. We believe these results can be valuable in designing and interpreting the results of ASF control programmes, and future work can also be undertaken as our dataset is released under open access, to perform studies in risk assessment for ASFV persistence in a region where O. erraticus sensu stricto ticks are present.

  16. Evaluation of DNA extraction protocols for Brucella abortus pcr detection in aborted fetuses or calves born from cows experimentally infected with strain 2308

    PubMed Central

    Matrone, M.; Keid, L.B.; Rocha, V.C.M.; Vejarano, M.P.; Ikuta, C.Y.; Rodriguez, C.A.R.; Ferreira, F.; Dias, R.A.; Ferreira Neto, J.S

    2009-01-01

    The objective of the present study was to improve the detection of B. abortus by PCR in organs of aborted fetuses from infected cows, an important mechanism to find infected herds on the eradication phase of the program. So, different DNA extraction protocols were compared, focusing the PCR detection of B. abortus in clinical samples collected from aborted fetuses or calves born from cows challenged with the 2308 B. abortus strain. Therefore, two gold standard groups were built based on classical bacteriology, formed from: 32 lungs (17 positives), 26 spleens (11 positives), 23 livers (8 positives) and 22 bronchial lymph nodes (7 positives). All samples were submitted to three DNA extraction protocols, followed by the same amplification process with the primers B4 and B5. From the accumulated results for organ, the proportion of positives for the lungs was higher than the livers (p=0.04) or bronchial lymph nodes (p=0.004) and equal to the spleens (p=0.18). From the accumulated results for DNA extraction protocol, the proportion of positives for the Boom protocol was bigger than the PK (p< 0.0001) and GT (p=0.0004). There was no difference between the PK and GT protocols (p=0.5). Some positive samples from the classical bacteriology were negative to the PCR and vice-versa. Therefore, the best strategy for B. abortus detection in the organs of aborted fetuses or calves born from infected cows is the use, in parallel, of isolation by classical bacteriology and the PCR, with the DNA extraction performed by the Boom protocol. PMID:24031391

  17. Experimental Infection of Ornithodoros erraticus sensu stricto with Two Portuguese African Swine Fever Virus Strains. Study of Factors Involved in the Dynamics of Infection in Ticks

    PubMed Central

    Madeira, Sara; Hutchings, Geoff H.; Boinas, Fernando

    2015-01-01

    African swine fever (ASF) is a frequently devastating hemorrhagic disease of domestic pigs and wild boar and Ornithodoros erraticus sensu stricto argasid ticks are the only biological vectors of African swine fever virus (ASFV) known to occur in Europe. Recently this disease emerged in Eastern Europe and Russian Federation, showing a huge potential for a rapid spread between countries. There is some risk of re-emergence of ASF in the countries where these ticks exist, that can contribute for the persistence of infection and compromise control measures. In this study we aimed to identify factors that determine the probability of infection and its dynamics in the tick vector Ornithodoros erraticus sensu stricto, with two Portuguese strains of ASFV. Our results suggest that these ticks have a high likelihood of excreting the two haemadsorbing ASF viruses of different host origins and that, in field surveys, the analysis of adults and 5th nymphal stage can provide the best chance of detecting virus infection. The results also indicate that infection of pigs with highly virulent ASF viruses will promote higher rates of infection and a higher likelihood for virus excretion by ticks. Nevertheless, there is also a risk, although lower, that ticks can become infected on pigs that have overcome the acute phase of infection, which was simulated in our study by membrane feeding ticks with low titres of virus. We believe these results can be valuable in designing and interpreting the results of ASF control programmes, and future work can also be undertaken as our dataset is released under open access, to perform studies in risk assessment for ASFV persistence in a region where O. erraticus sensu stricto ticks are present. PMID:26366570

  18. Theoretical analysis of the neuraminidase epitope of the Mexican A H1N1 influenza strain, and experimental studies on its interaction with rabbit and human hosts.

    PubMed

    Loyola, Paola Kinara Reyes; Campos-Rodríguez, R; Bello, Martiniano; Rojas-Hernández, S; Zimic, Mirko; Quiliano, Miguel; Briz, Verónica; Muñoz-Fernández, M Angeles; Tolentino-López, Luis; Correa-Basurto, Jose

    2013-05-01

    The neuraminidase (NA) epitope from the Mexican AH1N1 influenza virus was identified by using sequences registered at the GenBank during the peak of a pandemic (from April 2009 to October 2010). First, NA protein sequences were submitted for multiple alignment analysis, and their three-dimensional models (3-D) were then built by using homology modeling. The most common sequence (denominated wild-type) and its mutants were submitted to linear and nonlinear epitope predictors, which included the major histocompatibility complex type II (MHC II) and B-cell peptides. The epitope prediction was in accordance with evolutionary behavior and some protein structural properties. The latter included a low NA mutation rate, NA 3-D surface exposure, and the presence of high hindrance side chain residues. After selecting the epitope, docking studies and molecular dynamics (MD) simulations were used to explore interactions between the epitope and MHC II. Afterward, several experimental assays were performed to validate the theoretical study by using antibodies from humans (infected by pandemic H1N1) and rabbits (epitope vaccination). The results show 119 complete sequences that were grouped into 28 protein sequences according to their identity (one wild-type and 27 representative mutants (1-5 mutations)). The predictors yielded several epitopes, with the best fit being the one located in the C-terminal region. Theoretical methods demonstrated that the selected epitope reached the P4, P6, P7, and P9 pockets of MHC II, whereas the experimental evidence indicates that the epitope is recognized by human antibodies and also by rabbit antibodies immunized with the peptide.

  19. Efficacies of Imipenem, Meropenem, Cefepime, and Ceftazidime in Rats with Experimental Pneumonia Due to a Carbapenem-Hydrolyzing β-Lactamase-Producing Strain of Enterobacter cloacae

    PubMed Central

    Mimoz, Olivier; Leotard, Sophie; Jacolot, Anne; Padoin, Christophe; Louchahi, Kamel; Petitjean, Olivier; Nordmann, Patrice

    2000-01-01

    The antibacterial activities of imipenem-cilastatin, meropenem-cilastatin, cefepime and ceftazidime against Enterobacter cloacae NOR-1, which produces the carbapenem-hydrolyzing β-lactamase NmcA and a cephalosporinase, and against one of its in vitro-obtained ceftazidime-resistant mutant were compared by using an experimental model of pneumonia with immunocompetent rats. The MICs of the β-lactams with an inoculum of 5 log10 CFU/ml were as follows for E. cloacae NOR-1 and its ceftazidime-resistant mutant, respectively: imipenem, 16 and 128 μg/ml, meropenem, 4 and 32 μg/ml, cefepime, <0.03 and 1 μg/ml, and ceftazidime, 1 and 512 μg/ml. The chromosomally located cephalosporinase and carbapenem-hydrolyzing β-lactamase NmcA were inducible by cefoxitin and meropenem in E. cloacae NOR-1, and both were stably overproduced in the ceftazidime-resistant mutant. Renal impairment was induced (uranyl nitrate, 1 mg/kg of body weight) in rats to simulate the human pharmacokinetic parameters for the β-lactams studied. Animals were intratracheally inoculated with 8.5 log10 CFU of E. cloacae, and therapy was initiated 3 h later. At that time, animal lungs showed bilateral pneumonia containing more than 6 log10 CFU of E. cloacae per g of tissue. Despite the relative low MIC of meropenem for E. cloacae NOR-1, the carbapenem-treated rats had no decrease in bacterial counts in their lungs 60 h after therapy onset compared to the counts for the controls, regardless of whether E. cloacae NOR-1 or its ceftazidime-resistant mutant was inoculated. A significant decrease in bacterial titers was observed for the ceftazidime-treated rats infected with E. cloacae NOR-1 only. Cefepime was the only β-lactam tested effective as treatment against infections due to E. cloacae NOR-1 or its ceftazidime-resistant mutant. PMID:10722486

  20. Strained Ring Energetic Binders

    DTIC Science & Technology

    1993-08-27

    polyhomobenzvalene ( PHBV ). PHBV was not found to have the mechanical instability problems of PBV, but was still thermally unstable (Tonset - 660C, Tmax - 1090C...DISCUSSION 4 Polybenzvalene (PBV) 4 Polyhomobenzvalene ( PHBV ) 6 Chain-Transfer Studies 11 CONCLUSIONS 15 EXPERIMENTAL PROCEDURES 16 .F 4E 19 APPENDICES A...strained ring polymers similar to PBV are known. The investigation of one of these polymers, polyhomobenzvalene ( PHBV ), is also described in this report

  1. Deriving Strain Modes From Vibrational Tests

    NASA Technical Reports Server (NTRS)

    Young, J. W.; Joanides, J. C.

    1985-01-01

    Measurements and theoretical analysis complement each other. Experimental acceleration and strain data used to calculate coefficients of low-frequency vibrational modes of object under test. An iterative comparison of experimental and calculated strains give modal model of improved accuracy that predicts strains under operating conditions. Method useful in fatigue life and reliability analyses of buildings, pumps, engines, vehicles, and other systems subject to vibrations and loud noises during operation.

  2. Efficacy of Bacteriophage Therapy in Experimental Sepsis and Meningitis Caused by a Clone O25b:H4-ST131 Escherichia coli Strain Producing CTX-M-15

    PubMed Central

    Pouillot, Flavie; Chomton, Maryline; Blois, Hélène; Courroux, Celine; Noelig, Julien; Bidet, Philippe; Bingen, Edouard

    2012-01-01

    We evaluated phage therapy in experimental infections due to S242, a fatal neonatal meningitis Escherichia coli strain belonging to the worldwide-distributed O25b:H4-ST131 clone that produces extended-spectrum beta-lactamase CTX-M-15. A lytic phage, EC200PP, active against S242, was isolated from environmental water. After determining in vitro and ex vivo stabilities and pharmacokinetic properties of EC200PP in rat pups, we assessed the therapeutic efficacy of a single dose of 108 PFU using models of sepsis and meningitis in which fatality was 100%. EC200PP was partially neutralized by human serum. In contrast to the high concentration of phage in the spleen and the kidney, low titers in urine and the central nervous system were observed. Nevertheless, in the sepsis model, EC200PP administered 7 h or 24 h postinfection resulted in 100% and 50% pup survival, respectively. In the meningitis model, EC200PP administered 1 h or 7 h postinfection rescued 100% of the animals. The most delayed treatments were associated with the selection of phage-resistant S242 mutants. However, a representative mutant was highly sensitive to killing serum activity and avirulent in an animal model. EC200PP is a potential therapeutic agent for sepsis and meningitis caused by the widespread E. coli O25:H4-ST131 multidrug-resistant clone. PMID:22491690

  3. Efficacy of bacteriophage therapy in experimental sepsis and meningitis caused by a clone O25b:H4-ST131 Escherichia coli strain producing CTX-M-15.

    PubMed

    Pouillot, Flavie; Chomton, Maryline; Blois, Hélène; Courroux, Celine; Noelig, Julien; Bidet, Philippe; Bingen, Edouard; Bonacorsi, Stéphane

    2012-07-01

    We evaluated phage therapy in experimental infections due to S242, a fatal neonatal meningitis Escherichia coli strain belonging to the worldwide-distributed O25b:H4-ST131 clone that produces extended-spectrum beta-lactamase CTX-M-15. A lytic phage, EC200(PP), active against S242, was isolated from environmental water. After determining in vitro and ex vivo stabilities and pharmacokinetic properties of EC200(PP) in rat pups, we assessed the therapeutic efficacy of a single dose of 10(8) PFU using models of sepsis and meningitis in which fatality was 100%. EC200(PP) was partially neutralized by human serum. In contrast to the high concentration of phage in the spleen and the kidney, low titers in urine and the central nervous system were observed. Nevertheless, in the sepsis model, EC200(PP) administered 7 h or 24 h postinfection resulted in 100% and 50% pup survival, respectively. In the meningitis model, EC200(PP) administered 1 h or 7 h postinfection rescued 100% of the animals. The most delayed treatments were associated with the selection of phage-resistant S242 mutants. However, a representative mutant was highly sensitive to killing serum activity and avirulent in an animal model. EC200(PP) is a potential therapeutic agent for sepsis and meningitis caused by the widespread E. coli O25:H4-ST131 multidrug-resistant clone.

  4. Eight-year observation and comparative study of specific pathogen-free cats experimentally infected with feline immunodeficiency virus (FIV) subtypes A and B: terminal acquired immunodeficiency syndrome in a cat infected with FIV petaluma strain.

    PubMed

    Kohmoto, M; Uetsuka, K; Ikeda, Y; Inoshima, Y; Shimojima, M; Sato, E; Inada, G; Toyosaki, T; Miyazawa, T; Doi, K; Mikami, T

    1998-03-01

    Three specific pathogen-free cats experimentally infected with feline immunodeficiency virus (FIV) strains Petaluma, TM1 and TM2, respectively were observed for over 8 years. Without showing any significant clinical signs of immunodeficiency syndrome (AIDS) for 8 years and 4 months of asymptomatic phase, the Petaluma-infected cat exhibited severe stomatitis/gingivitis, anorexia, emaciation, hematological and immunological disorders such as severe anemia, lymphopenia, thrombocytopenia, and decrease of CD4/CD8 ratio to 0.075, and finally died with hemoperitoneum at 8 years and 8 months post-infection. Histopathological studies revealed that the cat had systemic lymphoid atrophy and bone marrow disorders indicating acute myelocytic leukemia (aleukemic type). Plasma viral titer of the cat at AIDS phase was considerably high and anti-FIV antibody titer was slightly low as compared with the other FIV-infected cats. In addition, immunoblotting analysis using serially collected serum/plasma samples of these cats revealed that antibodies against FIV proteins were induced in all the infected cats, however in the Petaluma-infected cat anti-Gag antibodies disappeared during the asymptomatic period. These results suggested that plasma viral load and anti-FIV Gag antibody response correlated with disease progression, and supported FIV-infected cats as a suitable animal model of human AIDS.

  5. Novel rope-based sampling of classical swine fever shedding in a group of wild boar showing low contagiosity upon experimental infection with a classical swine fever field strain of genotype 2.3.

    PubMed

    Mouchantat, Susan; Globig, Anja; Böhle, Wolfgang; Petrov, Anja; Strebelow, Heinz-Günther; Mettenleiter, Thomas C; Depner, Klaus

    2014-06-04

    Several classical swine fever (CSF) epidemics in wild boar and domestic pigs in Europe during the last decades have been caused by CSF virus (CSFV) strains of genotype 2.3. This genotype is known to be virulent leading to high morbidity and mortality. We experimentally infected two eight months old wild boar with 10(5,5) TCID50 of CSFV genotype 2.3 and kept the animals together with five noninoculated wild boar of the same age. Our original purpose was to evaluate a non-invasive sampling method based on saliva collection using "rope-in-a-bait" sampling baits. While expecting high morbidity, high level of virus shedding and some mortality, we actually observed a subclinical course of infection with an unexpected low contagiosity. The two inoculated animals infected only three contact animals while two contact animals remained uninfected. These findings substantially add to our epidemiological understanding of CSFV circulation in wild boar populations. CSFV infected animals older than six months and in good condition may not shed sufficient virus to transmit infection to all seronegative in-contact animals. The contagiosity in relation to the animal's age is discussed. This supports the hypothesis of silent perpetuation of CSFV in wild boar populations for several months if the wild boar density is sufficiently high. The feasibility of the "rope-in-a-bait" sampling method could be proven during the short viraemic phase of infected animals during the second week of infection.

  6. Residual strains in conduit arteries.

    PubMed

    Rachev, A; Greenwald, S E

    2003-05-01

    Residual strains and stresses are those that exist in a body when all external loads are removed. Residual strains in arteries can be characterized by the opening angle of the sector-like cross-section which arises when an unloaded ring segment is radially cut. A review of experimental methods for measuring residual strains and the main results about the variation of the opening angle with arterial localization, age, smooth muscle activity, mechanical environment and certain vascular pathologies are presented and discussed. It is shown that, in addition to their well-established ability to homogenize the stress field in the arterial wall, residual strains make arteries more compliant and thereby improve their performance as elastic reservoirs and ensure more effective local control of the arterial lumen by smooth muscle cells. Finally, evidence that, in some cases, residual strains remain in arteries even after they have been cut radially is discussed.

  7. Hip flexor strain - aftercare

    MedlinePlus

    ... flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  8. Quantification and determination of spread mechanisms of bovine viral diarrhoea virus in blood and tissues from colostrum-deprived calves during an experimental acute infection induced by a non-cytopathic genotype 1 strain.

    PubMed

    Pedrera, M; Gómez-Villamandos, J C; Molina, V; Risalde, M A; Rodríguez-Sánchez, B; Sánchez-Cordón, P J

    2012-10-01

    To detect and monitor the sequential changes in virus levels, a reverse transcription quantitative real-time polymerase chain reaction assay using a TaqMan probe was carried out on frozen blood and tissues samples collected from calves experimentally infected with a non-cytopathic Bovine viral diarrhoea virus (BVDV) genotype 1 strain. Blood samples were collected among days 1-14 post-inoculation (p.i). On day 3 p.i, viral RNA was detected in blood samples from six of the eight inoculated animals. Viral RNA was detected in all remaining inoculated animals between 5 and 12 days p.i. The levels of viral RNA increased along the experiment, with a maximal peak between 6 and 9 days p.i. Analysis of virus load in tissues collected from calves euthanized on days 3, 6, 9 and 14 p.i displayed that BVDV was detected on day 3 p.i, being especially abundant in tonsils and ileocaecal valve, highlighting the role of tonsils as the main earliest viral replication sites as well as the principal source for virus spread to other lymphoid tissues and visceral organs. Coinciding with the highest viraemia levels, the highest viral loads were recorded at 9 days p.i. in tonsils, ileal lymph nodes, distal ileum and spleen, showing the main role of these secondary lymphoid organs in the pathogenic mechanisms of BVDV. However, virus levels in the liver and lung increased only towards the end of the infection. This fact could influence in the appearance of bovine respiratory diseases because of the capacity of BVDV for enhancing susceptibility to secondary infections.

  9. Yield strain in shear banding amorphous solids.

    PubMed

    Dasgupta, Ratul; Hentschel, H George E; Procaccia, Itamar

    2013-02-01

    In recent research it was found that the fundamental shear-localizing instability of amorphous solids under external strain, which eventually results in a shear band and failure, consists of a highly correlated array of Eshelby quadrupoles all having the same orientation and some density ρ. In this paper we calculate analytically the energy E(ρ,γ) associated with such highly correlated structures as a function of the density ρ and the external strain γ. We show that for strains smaller than a characteristic strain γ(Y) the total strain energy initially increases as the quadrupole density increases, but that for strains larger than γ(Y) the energy monotonically decreases with quadrupole density. We identify γ(Y) as the yield strain. Its value, derived from values of the qudrupole strength based on the atomistic model, agrees with that from the computed stress-strain curves and broadly with experimental results.

  10. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  11. Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

    NASA Technical Reports Server (NTRS)

    Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.

    1981-01-01

    A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

  12. Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

    NASA Technical Reports Server (NTRS)

    Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.

    1981-01-01

    A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

  13. Fundamental understanding of piezoelectric strain sensors

    NASA Astrophysics Data System (ADS)

    Sirohi, Jayant; Chopra, Inderjit

    1999-06-01

    This paper investigates the behavior of piezoelectric elements as strain sensors. Strain is measured in terms of the charge generated by the element as a result of the direct piezoelectric effect. Strains from piezoceramic and piezofilm sensors are compared with strains from a conventional foil strain gage and the advantages of each type of sensor are discussed, along with their limitations. The sensors are surface bonded and are calibrated by means of a dynamic beam bending setup over a frequency range of 5 - 500 Hz. Correction factors to account for transverse strain and shear lag effects due to the bond layer are analytically derived and validated experimentally. Additionally, design of signal conditioning electronics to collect the signals from the piezoelectric sensors is addressed. The superior performance of piezoelectric sensors compared to conventional strain gages in terms of sensitivity and signal to noise ratio is demonstrated.

  14. Geobacteraceae strains and methods

    DOEpatents

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  15. Drop of egg production in chickens by experimental infection with an avian metapneumovirus strain PLE8T1 derived from swollen head syndrome and the application to evaluate vaccine.

    PubMed

    Sugiyama, Miki; Koimaru, Hiroyuki; Shiba, Masahiro; Ono, Eriko; Nagata, Tadashi; Ito, Toshihiro

    2006-08-01

    Decreases in egg production and increased incidence of abnormal eggs due to malformation of egg shells were observed in specific pathogen free (SPF) 173-day-old laying hens inoculated intravenously with an avian metapneumovirus (aMPV) strain PLE8T1. This strain was derived from an isolate from broiler birds exhibiting swollen head syndrome (SHS). Some SPF birds inoculated with the virus showed, slight diarrhea without any respiratory symptoms. Thus, the PLE8T1 strain was used as a challenge virus to evaluate efficacy of aMPV vaccines. SPF chickens which received a live attenuated aMPV vaccine (NEMOVAC; Merial) at 7 or 77 days old and an inactivated aMPV vaccine (OVO-4; Merial) at 105 days old were protected against poor egg production caused by the challenge with the PLE8T1 strain. Thus, aMPV, the PLE8T1 strain passaged 22 times after isolation, from birds exhibiting SHS, could induce a drop in egg production in laying hens accompanied by malformation of egg shells. It was suggested that this challenge system could be applied to evaluate the efficacy of aMPV vaccine.

  16. Determination of Dynamic Recrystallization Process by Equivalent Strain

    NASA Astrophysics Data System (ADS)

    Qin, Xiaomei; Deng, Wei

    Based on Tpнoвckiй's displacement field, equivalent strain expression was derived. And according to the dynamic recrystallization (DRX) critical strain, DRX process was determined by equivalent strain. It was found that equivalent strain distribution in deformed specimen is inhomogeneous, and it increases with increasing true strain. Under a certain true strain, equivalent strains at the center, demisemi radius or on tangential plane just below the surface of the specimen are higher than the true strain. Thus, micrographs at those positions can not exactly reflect the true microstructures under the certain true strain. With increasing strain rate, the initial and finish time of DRX decrease. The frozen microstructures of 20Mn23AlV steel with the experimental condition validate the feasibility of predicting DRX process by equivalent strain.

  17. Muscle strain treatment

    MedlinePlus

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  18. Muscle strain (image)

    MedlinePlus

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  19. On the use of strain sensor technologies for strain modal analysis: Case studies in aeronautical applications

    NASA Astrophysics Data System (ADS)

    Marques dos Santos, Fábio Luis; Peeters, Bart

    2016-10-01

    This paper discusses the use of optical fiber Bragg grating (FBG) and piezo strain sensors for structural dynamic measurements. For certain industrial applications, there is an interest to use strain sensors rather than in combination with accelerometers for experimental modal analysis. Classical electrical strain gauges can be used hereto, but other types of strain sensors are an interesting alternative with some very specific advantages. This work gives an overview of two types of dynamic strain sensors, applied to two industrial applications (a helicopter main rotor blade and an F-16 aircraft), FBG sensors and dynamic piezo strain sensors, discussing their use and benefits. Moreover, the concept of strain modal analysis is introduced and it is shown how it can be beneficial to apply strain measurements to experimental modal analysis. Finally, experimental results for the two applications are shown, with an experimental modal analysis carried out on the helicopter main rotor blade using FBG sensors and a similar experiment is done with the aircraft but using piezo strain sensors instead.

  20. A combination of experimental and numerical methods to investigate the role of strain rate on the mechanical properties and collagen fiber orientations of the healthy and atherosclerotic human coronary arteries.

    PubMed

    Karimi, Alireza; Rahmati, Seyyed Mohammadali; Sera, Toshihiro; Kudo, Susumu; Navidbakhsh, Mahdi

    2017-03-04

    Atherosclerosis enables to alter not only the microstructural but also the physical properties of the arterial walls by plaque forming. Few studies so far have been conducted to calculate the isotropic or anisotropic mechanical properties of the healthy and atherosclerotic human coronary arteries. To date there is a paucity of knowledge on the mechanical response of the arteries under different strain rates. Therefore, the objective of the concurrent research was to comprehend whether the alteration in the strain rates of the human atherosclerotic arteries in comparison with the healthy ones contribute to the biomechanical behaviors. To do this, healthy and atherosclerotic human coronary arteries were removed from 18 individuals during autopsy. Histological analyses by both an expert histopathologist and an imaged-based recognizer software were performed to figure out the average angle of collagen fibers in the healthy and atherosclerotic arterial walls. Thereafter, the samples were subjected to 3 diverse strain rates, i.e., 5, 20, and 50 mm/min, until the material failure occurs. The stress-strain diagrams of the arterial tissues were calculated in order to capture their linear elastic and nonlinear hyperelastic mechanical properties. In addition, Artificial Neural Networks (ANNs) was employed to predict the alteration of mean angle of collagen fibers during load bearing up to failure. The findings suggest that strain rate has a significant (p < 0.05) role in the linear elastic and nonlinear hyperelastic mechanical properties as well as the mean angle of collagen fibers of the atherosclerotic arteries, whereas no specific impact on the healthy ones. Furthermore, the mean angle of collagen fibers during the load bearing up to the failure at each strain rate was well predicted by the proposed ANNs code.

  1. A combination of experimental and numerical methods to investigate the role of strain rate on the mechanical properties and collagen fiber orientations of the healthy and atherosclerotic human coronary arteries

    PubMed Central

    Karimi, Alireza; Rahmati, Seyyed Mohammadali; Sera, Toshihiro; Kudo, Susumu; Navidbakhsh, Mahdi

    2017-01-01

    ABSTRACT Atherosclerosis enables to alter not only the microstructural but also the physical properties of the arterial walls by plaque forming. Few studies so far have been conducted to calculate the isotropic or anisotropic mechanical properties of the healthy and atherosclerotic human coronary arteries. To date there is a paucity of knowledge on the mechanical response of the arteries under different strain rates. Therefore, the objective of the concurrent research was to comprehend whether the alteration in the strain rates of the human atherosclerotic arteries in comparison with the healthy ones contribute to the biomechanical behaviors. To do this, healthy and atherosclerotic human coronary arteries were removed from 18 individuals during autopsy. Histological analyses by both an expert histopathologist and an imaged-based recognizer software were performed to figure out the average angle of collagen fibers in the healthy and atherosclerotic arterial walls. Thereafter, the samples were subjected to 3 diverse strain rates, i.e., 5, 20, and 50 mm/min, until the material failure occurs. The stress-strain diagrams of the arterial tissues were calculated in order to capture their linear elastic and nonlinear hyperelastic mechanical properties. In addition, Artificial Neural Networks (ANNs) was employed to predict the alteration of mean angle of collagen fibers during load bearing up to failure. The findings suggest that strain rate has a significant (p < 0.05) role in the linear elastic and nonlinear hyperelastic mechanical properties as well as the mean angle of collagen fibers of the atherosclerotic arteries, whereas no specific impact on the healthy ones. Furthermore, the mean angle of collagen fibers during the load bearing up to the failure at each strain rate was well predicted by the proposed ANNs code. PMID:27588460

  2. Predictions Of Fatigue Damage From Strain Histories

    NASA Technical Reports Server (NTRS)

    Sire, Robert A.; Besuner, Philip M.; Toomey, Tim

    1989-01-01

    Semiempirical mathematical model of fatigue damage in stressed objects uses experimental histories of strains in those objects to predict fatigue lives. Accounts for initiation and propagation of fatigue cracks on cycle-by-cycle basis. Measured strain history first digitized, then converted to history of turning-point strains for purposes of analysis. Data between turning points not used. When model calibrated against proper test data for each type of object characterized, its predictions of fatigue lives superior to statistical models as one based on root-mean-square strain.

  3. Rhoptry Proteins ROP5 and ROP18 Are Major Murine Virulence Factors in Genetically Divergent South American Strains of Toxoplasma gondii

    PubMed Central

    Lauron, Elvin J.; Jimah, John R.; Wang, Qiuling; Tolia, Niraj H.; Sibley, L. David

    2015-01-01

    Toxoplasma gondii has evolved a number of strategies to evade immune responses in its many hosts. Previous genetic mapping of crosses between clonal type 1, 2, and 3 strains of T. gondii, which are prevalent in Europe and North America, identified two rhoptry proteins, ROP5 and ROP18, that function together to block innate immune mechanisms activated by interferon gamma (IFNg) in murine hosts. However, the contribution of these and other virulence factors in more genetically divergent South American strains is unknown. Here we utilized a cross between the intermediately virulent North American type 2 ME49 strain and the highly virulent South American type 10 VAND strain to map the genetic basis for differences in virulence in the mouse. Quantitative trait locus (QTL) analysis of this new cross identified one peak that spanned the ROP5 locus on chromosome XII. CRISPR-Cas9 mediated deletion of all copies of ROP5 in the VAND strain rendered it avirulent and complementation confirmed that ROP5 is the major virulence factor accounting for differences between type 2 and type 10 strains. To extend these observations to other virulent South American strains representing distinct genetic populations, we knocked out ROP5 in type 8 TgCtBr5 and type 4 TgCtBr18 strains, resulting in complete loss of virulence in both backgrounds. Consistent with this, polymorphisms that show strong signatures of positive selection in ROP5 were shown to correspond to regions known to interface with host immunity factors. Because ROP5 and ROP18 function together to resist innate immune mechanisms, and a significant interaction between them was identified in a two-locus scan, we also assessed the role of ROP18 in the virulence of South American strains. Deletion of ROP18 in South American type 4, 8, and 10 strains resulted in complete attenuation in contrast to a partial loss of virulence seen for ROP18 knockouts in previously described type 1 parasites. These data show that ROP5 and ROP18 are

  4. Strain softening in stretched DNA

    PubMed Central

    Luan, Binquan; Aksimentiev, Aleksei

    2010-01-01

    The microscopic mechanics of DNA stretching was characterized using extensive molecular dynamics simulations. By employing an anisotropic pressure control method, realistic force-extension dependences of effectively infinite DNA molecules were obtained. A coexistence of B- and S-DNA domains was observed during the overstretching transition. The simulations revealed that strain softening may occur in the process of stretching torsionally constrained DNA. The latter observation was qualitatively reconciled with available experimental data using a random-field Ising model. PMID:18851334

  5. Magnetic susceptibility, petrofabrics and strain

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1988-12-01

    Magnetic susceptibility is a non-destructive technique for quantifying the average fabric of a small sample of rock. The interpretation of the magnetic fabric is not always straightforward. However, the principal directions of the magnitude ellipsoid of susceptibility commonly show orientations consistent with the kinematic interpretations of folds, shear zones and other structural features. The directions may correspond with the orientations of strained objects or with the planar-linear mineral orientations. There will usually be multiple mineralogical sources of susceptibility, often involving silicates. If the sources are known, or if the susceptibility can be attributed to a single mineral species, it may be possible to establish a correlation between the strain ellipsoid and the susceptibility ellipsoid. This correlation will be of principal directions in many instances and occasionally there may be a weak correlation of strain magnitudes as well. In other circumstances it may be possible to establish a correlation between changes in susceptibility and the strain. Nevertheless magnetic fabric studies are not routine substitutes for strain analysis. Even where information on strain is not provided, the magnetic fabrics (and subfabrics) yield a measure of the preferred crystallographic orientation or preferred dimensional orientation of the minerals that may be integrated profitably with other petrofabric data. Experimental deformation of certain synthetic aggregates indicates that directions of magnetic susceptibility spin rapidly with advancing strain, especially where the matrix grains undergo crystal-plastic deformation. In certain experiments, simple shear appears to change the intensity of magnetic fabric more effectively than pure shear. Experiments indicate also that the initial anisotropy of a rock-like material is not easily overprinted by deformation whereas field studies are equivocal.

  6. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  7. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  8. Smart composite structure based on integrated passive wireless strain sensors

    NASA Astrophysics Data System (ADS)

    Wong, Zi Jing; Kim, Chun-Gon

    2008-03-01

    This paper reports the development of low-cost inductively coupled passive wireless strain sensors which could be easily embedded within composite prepreg layers for structural health monitoring application. The sensors of 5 different patterns were fabricated and were experimentally tested. Theoretical modeling utilizing two different approaches and electromagnetic simulation were performed to estimate both the strain-free resonant frequency and the shift of resonant frequency of the sensor due to strain. Both the modeling and simulation results showed satisfactory agreement with the experimental data. The Terman model was found to give a better approximation of the strain-free resonant frequency, but the CAD model managed to predict the resonant frequency shift caused by strain more closer to the simulation result. Experimentally, all the sensors showed great strain sensing potential, as good linearity between resonant frequency and strain and relatively low hysteresis characteristics were observed. Finally, the feasibility of constructing sensor array was verified.

  9. CagA-positive Helicobacter pylori strain containing three EPIYA C phosphorylation sites produces increase of G cell and decrease of D cell in experimentally infected gerbils (Meriones unguiculatus).

    PubMed

    Júnior, Moacir Ferreira; Batista, Sérgio de Assis; Barbuto, Rafael Calvão; Gomes, Adriana Dias; Queiroz, Dulciene Maria Magalhães; Araújo, Ivana Duval; Caliari, Marcelo Vidigal

    2016-09-01

    Human infection by Helicobacter pylori is associated with an increase in the number of gastrin-producing G cells and a concomitant decrease of somatostatin-producing D cells. However, to our knowledge, changes in G and D cell numbers in response to infection with H. pylori CagA-positive strains containing different number of EPIYA-C phosphorylation sites have not been analyzed to date. Therefore, the aim of this study was to perform a quantitative analysis of the number of G and D cells in Mongolian gerbils challenged with H. pylori strains with different numbers of EPIYA-C motifs. Mongolian gerbils were inoculated with isogenic H. pylori strains containing one to three phosphorylation sites. Mucosal fragments were evaluated by morphometry and immunohistochemistry using primary polyclonal rabbit anti-gastrin and anti-somatostatin antibodies. Positive cells were counted using an image analyzer. Forty-five days after infection, there was a decrease in the number of D cells and an increase in the G/D cell ratio in the group with three EPIYA-C. Six months after infection, there was a progressive and significant increase in the number of G cells and in the G/D cell ratio, with a concomitant decrease in the number of D cells, especially in the three EPIYA-C group. CagA-positive H. pylori strains containing a large number of EPIYA-C phosphorylation sites induce a decrease in D cell number and an increase in G cell number and G/D ratio, which were correlated with the number of inflammatory cells of the lamina propria. Copyright © 2016 Medical University of Bialystok. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  10. The lapinized Chinese strain of hog cholera virus (HCV) previously adapted in minipig kidney (MPK) cell line cultures, would also protect pigs to experimental infection with virulent HCV [corrected].

    PubMed

    Rivero, V B; Gualandi, G L; Ferrari, M; Boldini, M; Buonavoglia, C; Mortarino, P

    1990-07-01

    Two-month old piglets previously inoculated with different dilutions of the Lapinized Chinese (LC) strain of Hog Cholera Virus (HCV), adapted in a minipig kidney (MPK) cell line, resisted challenge infection with virulent HCV. All the animals remained healthy and the challenge virus was never recovered from any of them. In contrast, the pigs which served as controls for the challenging virus underwent the clinically lethal form of the disease and HCV was consistently recovered from their tissues.

  11. HLA-DP, HLA-DQ, and HLA-DR-restricted epitopes in GRA5 of toxoplasma gondii strains

    NASA Astrophysics Data System (ADS)

    Haryati, S.; Sari, Y.; Prasetyo, A. A.; Sariyatun, R.

    2016-01-01

    The dense granular (GRA) proteins of Toxoplasma gondii(T. gondii) have been demonstrated as potential sources of T. gondii vaccine antigens. However, data of the GRA5 protein are limited. This study analyzed twenty-one complete GRA5 sequences of T. gondii GT1, RH, ME49, VEG, MAS, RUB, FOU, p89, VAND, and GAB2-2007-GAL-DOM2 strains to identify potential epitopes restricted by Major Histocompatibility Complex class II (MHC- II) molecules (human leukocyte antigen (HLA)-DP, HLA-DQ, and HLA-DR) in the protein. In all T. gondii strains, peptides positioned at amino acid (aa) 15-29, 16-30, 17-31, 18-32, 19-33, 83-97, 84-98, 86-100, 87-101, 89-103, and 90-104 were predicted to pose high affinity and binding with HLA-DRB1*0101, HLA-DRB1*0301 (DR17), HLA-DRB1*0401 (DR4Dw4), HLA-DRB1*0701, HLA-DRB1*1101, HLA-DRB1*1501 (DR2b), and/or HLA-DRB5*0101. Considering the epitope's affinity, ligation strength, and hydrophilicity, LRLLRRRRRRAIQEE sequence (aa 90-104) restricted by HLA-DRB1*0101, HlA- DRB1*0301 (DR17), and HLA-DRB1*0401 (DR4Dw4) was considered as the most potential MHC-II epitope in GRA5 of T. gondii. These results would be useful for studies concerning in developing T. gondii vaccine and diagnostic method.

  12. Influence of toxoplasmosis on acetylcholinesterase activity, nitric oxide levels and cellular lesion on the brain of mice.

    PubMed

    Tonin, Alexandre A; Da Silva, Aleksandro S; Thomé, Gustavo R; Sangoi, Manuela B; Oliveira, Lizielle S; Flores, Mariana M; Schetinger, Maria Rosa C; Fighera, Rafael A; Moresco, Rafael N; Camillo, Giovana; Vogel, Fernanda S F; Lopes, Sonia T A

    2014-08-01

    The objective of this study was to investigate the activity of acetylcholinesterase (AChE), nitrite/nitrate (NOx) levels, as well as the biomarkers of cellular damage in the brain of mice experimentally infected with Toxoplasma gondii. Sixty mice were divided into two experiments: in experiment I the mice were infected with T. gondii/RH strain, while in experiment II they were infected with T. gondii, strains VEG and ME-49. Our evaluations were carried out on brain homogenized samples, assessing the AChE and glutathione reductase (GR) activities, and NOx, TBARS and AOPP levels in all the infected animals, compared with the control group. In both experiments, I and II, it was observed an increase in the activity of AChE and GR, as well as in the levels of NOx in the brain of infected mice with T. gondii. TBARS levels were increased in mice infected with the three different strains, RH, ME-49, and VEG. AOPP concentration was increased only in mice infected with the RH strain. Animals infected with the strains VEG and ME-49 showed histological lesions, associated with the presence of the parasite in the brain. Therefore, the infection by T. gondii is able to interfere in cholinesterase activity and NO levels, in association with oxidative stress and histological lesion. Copyright © 2014 Elsevier GmbH. All rights reserved.

  13. Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions.

    PubMed

    Dubey, Jitender P; Ferreira, Leandra R; Alsaad, Mohammad; Verma, Shiv K; Alves, Derron A; Holland, Gary N; McConkey, Glenn A

    2016-01-01

    The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse. Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains) of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection) of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i.) to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25%) of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg muscle. This study reevaluated in depth the

  14. Experimental Toxoplasmosis in Rats Induced Orally with Eleven Strains of Toxoplasma gondii of Seven Genotypes: Tissue Tropism, Tissue Cyst Size, Neural Lesions, Tissue Cyst Rupture without Reactivation, and Ocular Lesions

    PubMed Central

    Dubey, Jitender P.; Ferreira, Leandra R.; Alsaad, Mohammad; Verma, Shiv K.; Alves, Derron A.; Holland, Gary N.; McConkey, Glenn A.

    2016-01-01

    Background The protozoan parasite Toxoplasma gondii is one of the most widely distributed and successful parasites. Toxoplasma gondii alters rodent behavior such that infected rodents reverse their fear of cat odor, and indeed are attracted rather than repelled by feline urine. The location of the parasite encysted in the brain may influence this behavior. However, most studies are based on the highly susceptible rodent, the mouse. Methodology/Principal Findings Latent toxoplasmosis was induced in rats (10 rats per T. gondii strains) of the same age, strain, and sex, after oral inoculation with oocysts (natural route and natural stage of infection) of 11 T. gondii strains of seven genotypes. Rats were euthanized at two months post inoculation (p.i.) to investigate whether the parasite genotype affects the distribution, location, tissue cyst size, or lesions. Tissue cysts were enumerated in different regions of the brains, both in histological sections as well in saline homogenates. Tissue cysts were found in all regions of the brain. The tissue cyst density in different brain regions varied extensively between rats with many regions highly infected in some animals. Overall, the colliculus was most highly infected although there was a large amount of variability. The cerebral cortex, thalamus, and cerebellum had higher tissue cyst densities and two strains exhibited tropism for the colliculus and olfactory bulb. Histologically, lesions were confined to the brain and eyes. Tissue cyst rupture was frequent with no clear evidence for reactivation of tachyzoites. Ocular lesions were found in 23 (25%) of 92 rat eyes at two months p.i. The predominant lesion was focal inflammation in the retina. Tissue cysts were seen in the sclera of one and in the optic nerve of two rats. The choroid was not affected. Only tissue cysts, not active tachyzoite infections, were detected. Tissue cysts were seen in histological sections of tongue of 20 rats but not in myocardium and leg

  15. Infection with CagA-Positive Helicobacter Pylori Strain Containing Three EPIYA C Phosphorylation Sites is Associated with More Severe Gastric Lesions in Experimentally Infected Mongolian Gerbils (Meriones Unguiculatus)

    PubMed Central

    Junior, M. Ferreira; Batista, S.A.; Vidigal, P.V.T; Cordeiro, A.A.C.; Oliveira, F.M.S.; Prata, L.O.; Diniz, A.E.T.; Barral, C.M.; Barbuto, R.C.; Comes, A.D.; Araujo, I.D.; Queiroz, D.M.M.; Caliari, M.V.

    2015-01-01

    Infection with Helicobacter pylori strains containing high number of EPIYA-C phosphorylation sites in the CagA is associated with significant gastritis and increased risk of developing pre-malignant gastric lesions and gastric carcinoma. However, these findings have not been reproduced in animal models yet. Therefore, we investigated the effect on the gastric mucosa of Mongolian gerbil (Meriones unguiculatus) infected with CagA-positive H. pylori strains exhibiting one or three EPIYA-C phosphorilation sites. Mongolian gerbils were inoculated with H. pylori clonal isolates containing one or three EPIYA-C phosphorylation sites. Control group was composed by uninfected animals challenged with Brucella broth alone. Gastric fragments were evaluated by the modified Sydney System and digital morphometry. Clonal relatedness between the isolates was considered by the identical RAPD-PCR profiles and sequencing of five housekeeping genes, vacA i/d region and of oipA. The other virulence markers were present in both isolates (vacA s1i1d1m1, iceA2, and intact dupA). CagA of both isolates was translocated and phosphorylated in AGS cells. After 45 days of infection, there was a significant increase in the number of inflammatory cells and in the area of the lamina propria in the infected animals, notably in those infected by the CagA-positive strain with three EPIYA-C phosphorylation sites. After six months of infection, a high number of EPIYA-C phosphorylation sites was associated with progressive increase in the intensity of gastritis and in the area of the lamina propria. Atrophy, intestinal metaplasia, and dysplasia were also observed more frequently in animals infected with the CagA-positive isolate with three EPIYA-C sites. We conclude that infection with H. pylori strain carrying a high number of CagA EPIYA-C phosphorylation sites is associated with more severe gastric lesions in an animal model of H. pylori infection. PMID:26150158

  16. Measurement of Sorption-Induced Strain

    SciTech Connect

    Eric P. Robertson; Richard L. Christiansen

    2005-05-01

    Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from east-central Utah, U.S.A. using an apparatus developed jointly at the Idaho National Laboratory (Idaho Falls, Idaho, U.S.A.) and Colorado School of Mines (Golden, Colorado, U.S.A.). The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain instead of the more common usage of strain gauges, which require larger samples and longer equilibration times. With this apparatus, we showed that the swelling and shrinkage processes were reversible and that accurate strain data could be obtained in a shortened amount of time. A suite of strain curves was generated for these coals using gases that included carbon dioxide, nitrogen, methane, helium, and various mixtures of these gases. A Langmuir-type equation was applied to satisfactorily model the strain data obtained for pure gases. The sorption-induced strain measured in the subbituminous coal was larger than the high-volatile bituminous coal for all gases tested over the range of pressures used in the experimentation, with the CO2-induced strain for the subbituminous coal over twice as great at the bituminous coal.

  17. Skeletal muscle tensile strain dependence: hyperviscoelastic nonlinearity

    PubMed Central

    Wheatley, Benjamin B; Morrow, Duane A; Odegard, Gregory M; Kaufman, Kenton R; Donahue, Tammy L Haut

    2015-01-01

    Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of strain. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% strain. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for strain dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the strain dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p<0.0005) and mid-range relaxation (p<0.0005) increased significantly with strain level, while relaxation at longer time periods decreased with strain (p<0.0005). Time constants and overall relaxation ratio did not change with strain level (p>0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are strain-dependent at the tissue level. This strain dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model. PMID:26409235

  18. Micro-scale strain mapping technique: a tool to quantify strain partitioning during creep deformation

    NASA Astrophysics Data System (ADS)

    Quintanilla-Terminel, Alejandra; Zimmerman, Mark; Evans, Brian; Kohlstedt, David

    2016-04-01

    Several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total strain is necessary for establishing a better link between observed microstructures and mechanical data, as well as to allow more confident extrapolation from laboratory to natural conditions. In this contribution, we present the experimental and computational technique involved in micro-scale strain mapping (MSSM). The MSSM technique relies on analyzing the relative displacement of initially regularly spaced markers after deformation. We present several microfabrication techniques that permit us to pattern various rocks with micrometric and nanometric metal markers, as well as the challenges faced in working at high temperatures and pressures. A Hough transform algorithm was used to detect the markers and automate as much as possible the strain analysis. The von Mises strain is calculated for a set of n-points and their relative displacements, which allow us to map the strain at different length scales. We applied the MSSM technique to study strain partitioning during deformation creep of Carrara marble and San Carlos olivine at a confining pressure, Pc, of 300 MPa and homologous temperatures of 0.3 to 0.6. We measured the local strain and strain heterogeneity produced during creep deformation of split cylinders of Carrara marble under conventional triaxial loading to inelastic strains of 11 to 36% at a strain rate of 3x10-5s-1, Pc = 300 MPa and 400o < T <700oC. We conclude that the evolution of deformation structures in marble takes place over a substantial interval in strain and that the duration of this interval depends on strain rate, temperature, and pressure. Our first results on strain mapping of olivine deformed at T = 1150oC and Pc = 300 MPa demonstrate promise for characterizing intragranular strain and better defining the contribution of grain boundary sliding to the total strain.

  19. Experimental envenoming of mice with venom from the scorpion Centruroides limpidus limpidus: differences in mortality and symptoms with and without antibody therapy relating to differences in age, sex and strain of mouse.

    PubMed

    Padilla, Alejandro; Govezensky, Tzipe; Possani, Lourival D; Larralde, Carlos

    2003-06-01

    C57Bl/6J and BALB/cAnN inbred strains of mice differed significantly in mortality and symptoms when intoxicated subcutaneously with one LD(50) of venom from Centruroides limpidus limpidus. Higher mortality was observed in C57Bl/6J than in BALB/cAnN. Also, C57Bl/6J mice more quickly developed muscular and respiratory collapse whilst BALB/cAnN mice were hyperactive before dying. Also, the symptoms in the survivors lasted for 24 h in C57Bl/6J and for 2 h in BALB/cAnN. The age and sex of mice were also related to mortality: younger mice were more resistant than older mice and females were more susceptible than males, especially in the younger groups. Antivenom (horse F(ab')(2)) administration 5-10 min after envenoming of mice with one LD(50) rescued 60% of BALB/cAnN and 52% of C57Bl/6J mice, respectively. Results indicate that genetic background, gender and age differences are of consequence in the pathogenesis of C. limpidus scorpion envenomation in mice, and that timely treatment with active antivenom F(ab')(2) saves a significant fraction of intoxicated mice without statistically significant distinction of strains.

  20. Prediction of Transformation Strain Using Microtexture Data

    NASA Astrophysics Data System (ADS)

    Giri, Sushil K.; Biswas, Pinaki; Kundu, Saurabh

    2017-07-01

    The transformation strain, resulting from austenite-to-bainite transformation induced under both external stress and without stress, is estimated by employing two different mathematical models. These models use actual fractions of individual variants in every prior austenite grain, which are calculated using electron backscattered diffraction (EBSD) scans after reconstruction of prior austenite microstructure. The strains predicted by models match closely with the experimentally determined macrostrain obtained using dilation data.

  1. A balloon strain gage

    NASA Technical Reports Server (NTRS)

    Rand, J. L.

    1981-01-01

    This paper describes the development of a unique strain measuring device which is intended to monitor the state of strain in thin balloon films during flight. The gate is bonded directly to the film without significantly altering the state of strain or stress in the wall of the balloon. Results of a model balloon inflation are presented which indicate the gage to measure strain in a deployed balloon.

  2. Balloon film strain measurement

    NASA Technical Reports Server (NTRS)

    Rand, J. L.

    1983-01-01

    A discussion is presented of the results of a flight test program in which scientific research balloon material strain was measured in order to determine stress levels. Attention is given to material strain characteristics during the inflation, launch, ascent, and flight of a natural shape, zero-pressure scientific balloon. Measurements were conducted with a simple thin film strain transducer. Thermal, meridional and circumferential strain history data for the test flight are given.

  3. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1985-01-01

    Materials were evaluated that could be used in manufacturing electrical resistance strain gages for static strain measurements at temperatures at or above 1273 K. Strain gage materials must have a characteristic response to strain, temperature and time that is reproducible or that varies in a predictable manner within specified limits. Several metallic alloys were evaluated, as well as a series of transition metal carbides, nitrides and silicides.

  4. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  5. Recognition of Highly Diverse Type-1 and -2 Porcine Reproductive and Respiratory Syndrome Viruses (PRRSVs) by T-Lymphocytes Induced in Pigs after Experimental Infection with a Type-2 PRRSV Strain.

    PubMed

    Chung, Chungwon J; Cha, Sang-Ho; Grimm, Amanda L; Chung, Grace; Gibson, Kathleen A; Yoon, Kyoung-Jin; Parish, Steven M; Ho, Chak-Sum; Lee, Stephen S

    2016-01-01

    Live attenuated vaccines confer partial protection in pigs before the appearance of neutralizing antibodies, suggesting the contribution of cell-mediated immunity (CMI). However, PRRSV-specific T-lymphocyte responses and protective mechanisms need to be further defined. To this end, the hypothesis was tested that PRRSV-specific T-lymphocytes induced by exposure to type-2 PRRSV can recognize diverse isolates. An IFN-gamma ELISpot assay was used to enumerate PRRSV-specific T-lymphocytes from PRRSVSD23983-infected gilts and piglets born after in utero infection against 12 serologically and genetically distinct type-1 and -2 PRRSV isolates. The IFN-gamma ELISpot assay using synthetic peptides spanning all open reading frames of PRRSVSD23983 was utilized to localize epitopes recognized by T-lymphocytes. Virus neutralization tests were carried out using the challenge strain (type-2 PRRSVSD23983) and another strain (type-2 PRRSVVR2332) with high genetic similarity to evaluate cross-reactivity of neutralizing antibodies in gilts after PRRSVSD23983 infection. At 72 days post infection, T-lymphocytes from one of three PRRSVSD23983-infected gilts recognized all 12 diverse PRRSV isolates, while T-lymphocytes from the other two gilts recognized all but one isolate. Furthermore, five of nine 14-day-old piglets infected in utero with PRRSVSD23983 had broadly reactive T-lymphocytes, including one piglet that recognized all 12 isolates. Overlapping peptides encompassing all open reading frames of PRRSVSD23983 were used to identify ≥28 peptides with T-lymphocyte epitopes from 10 viral proteins. This included one peptide from the M protein that was recognized by T-lymphocytes from all three gilts representing two completely mismatched MHC haplotypes. In contrast to the broadly reactive T-lymphocytes, neutralizing antibody responses were specific to the infecting PRRSVSD23983 isolate. These results demonstrated that T-lymphocytes recognizing antigenically and genetically diverse

  6. Recognition of Highly Diverse Type-1 and -2 Porcine Reproductive and Respiratory Syndrome Viruses (PRRSVs) by T-Lymphocytes Induced in Pigs after Experimental Infection with a Type-2 PRRSV Strain

    PubMed Central

    Cha, Sang-Ho; Grimm, Amanda L.; Chung, Grace; Gibson, Kathleen A.; Yoon, Kyoung-Jin; Parish, Steven M.; Ho, Chak-Sum; Lee, Stephen S.

    2016-01-01

    Background/Aim Live attenuated vaccines confer partial protection in pigs before the appearance of neutralizing antibodies, suggesting the contribution of cell-mediated immunity (CMI). However, PRRSV-specific T-lymphocyte responses and protective mechanisms need to be further defined. To this end, the hypothesis was tested that PRRSV-specific T-lymphocytes induced by exposure to type-2 PRRSV can recognize diverse isolates. Methods An IFN-gamma ELISpot assay was used to enumerate PRRSV-specific T-lymphocytes from PRRSVSD23983-infected gilts and piglets born after in utero infection against 12 serologically and genetically distinct type-1 and -2 PRRSV isolates. The IFN-gamma ELISpot assay using synthetic peptides spanning all open reading frames of PRRSVSD23983 was utilized to localize epitopes recognized by T-lymphocytes. Virus neutralization tests were carried out using the challenge strain (type-2 PRRSVSD23983) and another strain (type-2 PRRSVVR2332) with high genetic similarity to evaluate cross-reactivity of neutralizing antibodies in gilts after PRRSVSD23983 infection. Results At 72 days post infection, T-lymphocytes from one of three PRRSVSD23983-infected gilts recognized all 12 diverse PRRSV isolates, while T-lymphocytes from the other two gilts recognized all but one isolate. Furthermore, five of nine 14-day-old piglets infected in utero with PRRSVSD23983 had broadly reactive T-lymphocytes, including one piglet that recognized all 12 isolates. Overlapping peptides encompassing all open reading frames of PRRSVSD23983 were used to identify ≥28 peptides with T-lymphocyte epitopes from 10 viral proteins. This included one peptide from the M protein that was recognized by T-lymphocytes from all three gilts representing two completely mismatched MHC haplotypes. In contrast to the broadly reactive T-lymphocytes, neutralizing antibody responses were specific to the infecting PRRSVSD23983 isolate. Conclusion These results demonstrated that T-lymphocytes recognizing

  7. Experimental characterization and theoretical modeling of the strain effect on the evolution and interband transitions of InAs quantum dots grown on InxGa1-xAs (0.0<=x<=0.3) metamorphic pseudosubstrates on GaAs wafers

    NASA Astrophysics Data System (ADS)

    Ghanad-Tavakoli, Shahram; Naser, Mohamed A.; Thompson, David A.; Jamal Deen, M.

    2009-09-01

    Experimental characterization and theoretical study of the interband transitions of self-assembled InAs quantum dots (QDs) grown on metamorphic pseudosubstrates of InxGa1-xAs (0.0⩽x⩽0.3) are reported. The effect of the varying underlying strain on the size distribution of InAs QDs and their photoluminescence emission wavelength is investigated by employing different substrate compositions. Atomic force microscopy images of the QDs show that the ratio of the height/lateral diameter of the QDs decreases with decreasing strain and the photoluminescence of the buried InAs QDs shows that the peak wavelength redshifts with increasing In mole fraction of the underlying pseudosubstrates. A theoretical model based on the Green's function technique is used to calculate the density of states (DOS) of the QDs for the different samples based on the measured dot geometries. From the DOS, the electron and hole energy levels can be obtained, yielding the possible interband transitions. Good agreement between the model and the experimental results is obtained by allowing for Ga incorporation, from the substrate and barrier layers, into the InAs QDs and it is found that the necessary Ga mole fraction varies linearly with the Ga mole fraction in the underlying InxGa1-xAs pseudosubstrate.

  8. Principal component analysis of shear strain effects.

    PubMed

    Chen, Hao; Varghese, Tomy

    2009-05-01

    Shear stresses are always present during quasi-static strain imaging, since tissue slippage occurs along the lateral and elevational directions during an axial deformation. Shear stress components along the axial deformation axes add to the axial deformation while perpendicular components introduce both lateral and elevational rigid motion and deformation artifacts into the estimated axial and lateral strain tensor images. A clear understanding of these artifacts introduced into the normal and shear strain tensor images with shear deformations is essential. In addition, signal processing techniques for improved depiction of the strain distribution is required. In this paper, we evaluate the impact of artifacts introduced due to lateral shear deformations on the normal strain tensors estimated by varying the lateral shear angle during an axial deformation. Shear strains are quantified using the lateral shear angle during the applied deformation. Simulation and experimental validation using uniformly elastic and single inclusion phantoms were performed. Variations in the elastographic signal-to-noise and contrast-to-noise ratios for axial deformations ranging from 0% to 5%, and for lateral deformations ranging from 0 to 5 degrees were evaluated. Our results demonstrate that the first and second principal component strain images provide higher signal-to-noise ratios of 20 dB with simulations and 10 dB under experimental conditions and contrast-to-noise ratio levels that are at least 20 dB higher when compared to the axial and lateral strain tensor images, when only lateral shear deformations are applied. For small axial deformations, the lateral shear deformations significantly reduces strain image quality, however the first principal component provides about a 1-2dB improvement over the axial strain tensor image. Lateral shear deformations also significantly increase the noise level in the axial and lateral strain tensor images with larger axial deformations

  9. The therapeutic effect of tigecycline, unlike that of Ceftazidime, is not influenced by whether the Klebsiella pneumoniae strain produces extended-spectrum β-lactamases in experimental pneumonia in rats.

    PubMed

    Goessens, Wil H F; Mouton, Johan W; Ten Kate, Marian T; Sörgel, Fritz; Kinzig, Martina; Bakker-Woudenberg, Irma A J M

    2013-01-01

    The efficacies of tigecycline and ceftazidime against fatal pneumonia in rats caused by an extended-spectrum β-lactamase (ESBL)-positive Klebsiella pneumoniae strain or its wild-type (WT) progenitor were compared. Ceftazidime at 12.5 or 50 mg/kg of body weight twice daily (b.i.d.) was effective (50% or 100% rat survival) in pneumonia caused by the WT isolate but unsuccessful (100% rat mortality) in pneumonia caused by the ESBL-positive variant. In contrast, tigecycline at 6.25, 12.5, or 25 mg/kg b.i.d. showed dosage-dependent efficacy up to 100% rat survival irrespective of the ESBL character of the infecting organism.

  10. Tensile stress-strain behavior of boron/aluminum laminates

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  11. Strain powered antennas

    NASA Astrophysics Data System (ADS)

    Domann, John P.; Carman, Greg P.

    2017-01-01

    This paper proposes the creation of strain powered antennas that radiate electromagnetic energy by mechanically vibrating a piezoelectric or piezomagnetic material. A closed form analytic model of electromagnetic radiation from a strain powered electrically small antenna is derived and analyzed. Fundamental scaling laws and the frequency dependence of strain powered antennas are discussed. The radiation efficiency of strain powered electrically small antennas is contrasted with a conventional electric dipole. Analytical results show that operating at the first mechanical resonance produces the most efficient strain powered radiation relative to electric dipole antennas. A resonant analysis is exploited to determine the material property space that produces efficient strain powered antennas. These results show how a properly designed strain powered antenna can radiate more efficiently than an equally sized electric dipole antenna.

  12. Strain Rate Effects on the Mechanical Response of Polypropylene-Based Composites Deformed at Small Strains

    SciTech Connect

    Pessey, D.; Bahlouli, N.; Ahzi, Said; Khaleel, Mohammad A.

    2008-06-01

    The mechanical properties and response of two composites based polypropylene (PP) have been determined for small strains and for a range of strain rates in the quasi static domain. These two materials are the talc-filled and non-filled high impact PP. Uni-axial tensile tests were performed at different strain rates in order to characterize the mechanical response and the strain rate effect. Experimental results showed that both unfilled and talc-filled high impact polypropylene were sensitive to strain rate and have a non linear behavior even at relatively low strains. SEM analysis has been conducted to obtain a better comprehension of deformation mechanisms involved during loading by observations of the microstructure evolution. For each of these two materials, two existing modeling approaches are proposed. The first one is a three-parameter nonlinear constitutive model based on the experimental results. The second is a micromechanically-based approach for the elastic-viscoplastic behavior of the composite materials. The stress-strain curves predicted by these models are in fairly good agreement with our experimental results.

  13. Hodographic approach to predicting inelastic strain at high temperature

    NASA Technical Reports Server (NTRS)

    Berkovits, A.

    1972-01-01

    An experimental study of the effect of continuous and discontinuous changes in strain rate on the relationship among strain rate, strain, and stress is described. Data from Udimet 700 in tension at 925 C were used in order to relate cyclic tensile creep to the monotonic properties of the material by means of the hodograph. The nature of modifications caused to the hodograph by discontinuous variation of the strain rate was determined from tests. Reloading at discontinuous strain rate caused reactivation of primary creep. A simple method, based on monotonic material properties, is proposed for predicting cyclic tensile creep response. Preliminary results of cyclic tests agree with predicted response.

  14. Strain measurement of spiral bevel gear using optical fiber gratings

    NASA Astrophysics Data System (ADS)

    Liu, Nianyun; Wang, Yiming; Zhou, Zude; Lou, Ping

    2017-04-01

    This paper presents a spiral bevel gear strain measurement using optical fiber gratings. High-speed and heavy-duty spiral bevel gear (SBG) is the key component of the power transmission of intersection axes. Its dynamic mechanical properties greatly influence the working performance of the machine. By building a strain detecting system based on FBG demodulation, we carried out real-time measurements of the distributed strain in the SBG with different torques and different rotation speed. The experimental results show a complete strain waveform from gear-in to gear-out, verifying the feasibility of measuring the strain of SBG using optical fiber gratings.

  15. Three dimensional strained semiconductors

    DOEpatents

    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.

  16. Strain sensor comprising a strain sensitive, two-mode optical

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1994-01-01

    A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired to be measured. The strain insensitive portion(s) may be fused to the strain sensitive portion to transmit light therethrough, so that the resulting pattern may be detected to determine the amount of strain by comparison with a similar fiber not subjected to strain, or with the light pattern produced when the fiber is not under strain.

  17. Strain-based fatigue data for Ti-6Al-4V ELI under fully-reversed and mean strain loads.

    PubMed

    Carrion, Patricio E; Shamsaei, Nima

    2016-06-01

    This article presents the experimental data supporting the study to obtain the mean strain/stress effects on the fatigue behavior of Ti-6Al-4V ELI. A series of strain-controlled fatigue experiments on Ti-6Al-4V ELI were performed at four strain ratios (-1, -0.5, 0, and 0.5). Two types of data are included for each specimen. These are the hysteresis stress-strain responses for the cycle in a log10 increment, and the maximum and minimum stress-strain responses for each cycle. Fatigue lives are also reported for all the experiments.

  18. Strain-based fatigue data for Ti–6Al–4V ELI under fully-reversed and mean strain loads

    PubMed Central

    Carrion, Patricio E.; Shamsaei, Nima

    2016-01-01

    This article presents the experimental data supporting the study to obtain the mean strain/stress effects on the fatigue behavior of Ti–6Al–4V ELI. A series of strain-controlled fatigue experiments on Ti–6Al–4V ELI were performed at four strain ratios (−1, −0.5, 0, and 0.5). Two types of data are included for each specimen. These are the hysteresis stress–strain responses for the cycle in a log10 increment, and the maximum and minimum stress–strain responses for each cycle. Fatigue lives are also reported for all the experiments. PMID:26952022

  19. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  20. Strained Silicon Photonics

    PubMed Central

    Schriever, Clemens; Bohley, Christian; Schilling, Jörg; Wehrspohn, Ralf B.

    2012-01-01

    A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon. PMID:28817015

  1. A Methodology for Measuring Strain in Power Semiconductors

    NASA Astrophysics Data System (ADS)

    Avery, Seth M.

    The objective of this work is to develop a strain measurement methodology for use in power electronics during electrical operation; such that strain models can be developed and used as the basis of an active strain controller---improving the reliability of power electronics modules. This research involves developing electronic speckle pattern interferometry (ESPI) into a technology capable of measuring thermal-mechanical strain in electrically active power semiconductors. ESPI is a non-contact optical technique capable of high resolution (approx. 10 nm) surface displacement measurements. This work has developed a 3-D ESPI test stand, where simultaneous in- and out-of-plane measured components are combined to accurately determine full-field surface displacement. Two cameras are used to capture both local (interconnect level) displacements and strains, and global (device level) displacements. Methods have been developed to enable strain measurements of larger loads, while avoiding speckle decorrelation (which limits ESPI measurement of large deformations). A method of extracting strain estimates directly from unfiltered and wrapped phase maps has been developed, simplifying data analysis. Experimental noise measurements are made and used to develop optimal filtering using model-based tracking and determined strain noise characteristics. The experimental results of this work are strain measurements made on the surface of a leadframe of an electrically active IGBT. A model-based tracking technique has been developed to allow for the optimal strain solution to be extracted from noisy displacement results. Also, an experimentally validated thermal-mechanical FE strain model has been developed. The results of this work demonstrate that in situ strain measurements in power devices are feasible. Using the procedures developed in the work, strain measurements at critical locations of strain, which limit device reliability, at relevant power levels can be completed.

  2. Mouse model of congenital infection with a non-virulent Toxoplasma gondii strain: Vertical transmission, "sterile" fetal damage, or both?

    PubMed

    Vargas-Villavicencio, J A; Cedillo-Peláez, C; Rico-Torres, C P; Besné-Mérida, A; García-Vázquez, F; Saldaña, J I; Correa, D

    2016-07-01

    Congenital transmission of Toxoplasma gondii may occur if the mother gets infected for the first time while pregnant. The risk of mother-to-child transmission depends on the gestation trimester at infection, being lowest in the first and highest in the last. Conversely, fetal damage is frequent and more severe at the beginning of pregnancy. The objective of this study was to evaluate congenital transmission and pathological aspects in the placenta and the fetus using a mouse model of congenital infection of the second gestation third. Forty-five female BALB/c mice were infected intravenously with 2.5-10.0 × 10(6) tachyzoites of the ME49 strain at middle gestation. Samples of maternal spleen and fetal/placental units were taken 72 h later. We determined parasite load and vertical transmission by qPCR, as well as damage macroscopically and by histopathology. With the lowest dose, 18% of the fetuses were infected. Also, 40% of fetuses/litter were altered, while this value was 10% in the control group (P < 0.05). These results are similar to those described in humans in terms of vertical transmission and fetal damage during the second third of gestation. The maternal spleen had 10-1000 times more tachyzoites than the placenta, and the later retained 90-99% of the parasites that could reach the fetus. Nevertheless, we found resorptions, abortions or fetal tissue damage in the presence but also in the absence of parasites. Our data indicate a strong protective effect of maternal organs and the placenta against fetal infection, but extensive damage of the later may led to resorption or abortion without vertical transmission. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. The premixed flame in uniform straining flow

    NASA Technical Reports Server (NTRS)

    Durbin, P. A.

    1982-01-01

    Characteristics of the premixed flame in uniform straining flow are investigated by the technique of activation-energy asymptotics. An inverse method is used, which avoids some of the restrictions of previous analyses. It is shown that this method recovers known results for adiabatic flames. New results for flames with heat loss are obtained, and it is shown that, in the presence of finite heat loss, straining can extinguish flames. A stability analysis shows that straining can suppress the cellular instability of flames with Lewis number less than unity. Strain can produce instability of flames with Lewis number greater than unity. A comparison shows quite good agreement between theoretical deductions and experimental observations of Ishizuka, Miyasaka & Law (1981).

  4. Raman-strain relations in highly strained Ge: Uniaxial ⟨100⟩, ⟨110⟩ and biaxial (001) stress

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Duchemin, I.; Pauc, N.; Hartmann, J. M.; Rouchon, D.; Widiez, J.; Niquet, Y. M.; Milord, L.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2017-02-01

    The application of high values of strain to Ge considerably improves its light emission properties and can even turn it into a direct band gap semiconductor. Raman spectroscopy is routinely used for strain measurements. Typical Raman-strain relationships that are used for Ge were defined up to ˜1% strain using phonon deformation potential theory. In this work, we have studied this relationship at higher strain levels by calculating and measuring the Raman spectral shift-strain relations in several different strain configurations. Since differences were shown between the usual phonon deformation potential theory and ab-initio calculations, we highlight the need for experimental calibrations. We have then measured the strain in highly strained Ge micro-bridges and micro-crosses using Raman spectroscopy performed in tandem with synchrotron based micro-diffraction. High values of strain are reported, which enable the calibration of the Raman-strain relations up to 1.8% of in plane strain for the (001) biaxial stress, 4.8% strain along ⟨100⟩, and 3.8% strain along ⟨110⟩. For Ge micro-bridges, oriented along ⟨100⟩, the nonlinearity of the Raman shift-strain relation is confirmed. For the ⟨110⟩ orientation, we have shown that an unexpected non-linearity in the Raman-strain relationship has also to be taken into account for high stress induction. This work demonstrates an unprecedented level of strain measurement for the ⟨110⟩ uniaxial stress and gives a better understanding of the Raman-strain relations in Ge.

  5. High temperature static strain measurement with an electrical resistance strain gage

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1992-01-01

    An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

  6. High temperature static strain measurement with an electrical resistance strain gage

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1992-01-01

    An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

  7. Effect of increasing the dietary tryptophan to lysine ratio on plasma levels of tryptophan, kynurenine and urea and on production traits in weaner pigs experimentally infected with an enterotoxigenic strain of Escherichia coli.

    PubMed

    Capozzalo, Meeka M; Kim, Jae Cheol; Htoo, John K; de Lange, Cornelius F M; Mullan, Bruce P; Hansen, Christian Fink; Resink, Jan-Willem; Stumbles, Phillip A; Hampson, David J; Pluske, John R

    2015-01-01

    This experiment examined if immune system stimulation of weaner pigs, initiated by inoculation an enterotoxigenic strain of Escherichia coli (ETEC), increased the requirement for dietary tryptophan (Trp), modulated the inflammatory response, altered plasma levels of Trp and its metabolite kynurenine (Kyn) and effected post-weaning diarrhoea. Individually housed pigs (n = 72) weaned at 21 d of age were allocated to one of six treatments (n = 12) according to a two by three factorial arrangement of (1) with or without ETEC infection and (2) three dietary ratios of standardised ileal digestible (SID) Trp to lysine (Lys) (SID Trp:Lys) of 0.16, 0.20 or 0.24, in a completely randomised block design. Pigs had ad libitum access to diets (per kg 14.13 MJ ME, 12.4 g SID Lys, 195 g crude protein) for 3 weeks after weaning. Pigs were infected with ETEC (O149:K98:K88) at 72, 96 and 120 h after weaning and then bled on day 3, 11 and 19. An increased dietary Trp:Lys ratio increased plasma Trp and Kyn (p < 0.001) without effect of infection. On day 3, pigs fed 0.24 SID Trp:Lys had lower levels of plasma urea than at 0.20 Trp:Lys (p = 0.047) and on day 11, plasma urea was lower at 0.20 than at 0.16 SID Trp:Lys (p = 0.007). Infection increased (p = 0.039) the diarrhoea index and deteriorated faecal consistency from day 4-10 (p < 0.05). Treatments did not affect haptoglobin and acid soluble glycoprotein levels or daily gain and feed intake. However, 0.24 SID Trp:Lys improved (p = 0.021) feed efficiency without an effect of infection. In conclusion, in the absence of dietary antibiotic growth promotants, increasing the dietary SID Trp:Lys ratio to 0.24 improved feed conversion ratio after weaning and increased plasma levels of Trp and Kyn regardless of infection with E. coli.

  8. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  9. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  10. Chitinase producing Bt strains

    Treesearch

    Haim B. Gunner; Matthew Zimet; Sarah Berger

    1985-01-01

    Screening of 402 strains of more than 18 varieties of Bacillus thuringiensis showed chitinase to be inducible in virtually every serovar tested. Though the chitinase titre varied among strains, there was a strong correlation between enhanced lethality to spruce budworm, Choristoneura fumiferana (Clemens), and an increase in...

  11. Hamstring strain - aftercare

    MedlinePlus

    ... mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends on the grade of the ... be healing as expected. Alternative Names Pulled hamstring muscle; Sprain - ... Ali K, Leland JM. Hamstring strains and tears in the athlete. Clin Sports Med . 2012;31( ...

  12. A resistance strain gage with repeatable apparent strain to 800 C

    NASA Technical Reports Server (NTRS)

    Lei, J.-F.

    1991-01-01

    Experimental PdCr temperature-compensated resistance static-strain gages are described. The gages are developed in both fine-wire and thin-film forms. It is found that a PdCr wire strain gage coated with a flame-sprayed mixture of alumina and 4 wt pct zirconia demonstrates the smallest variation in and the best repeatability of apparent strain among the existing gages used at temperatures up to 800 C. Results of preliminary tests indicate uncompensated uncoated thin-film gages have potential usefulness at temperatures up to 1000 C.

  13. Elastoplastic notch root strains - Measurements versus finite-element predictions

    NASA Technical Reports Server (NTRS)

    Tregoning, R. L.

    1992-01-01

    A study intended to experimentally and computationally probe the nature of the elastoplastic strain fields created by notches with various levels of constraint is presented. An interferometric strain/displacement gage is used to measure both the axial and lateral strain at the center of a machined and polished notch. The monotonic response of various notches is determined using 3D finite-element calculations.

  14. Resistance fail strain gage technology as applied to composite materials

    NASA Technical Reports Server (NTRS)

    Tuttle, M. E.; Brinson, H. F.

    1985-01-01

    Existing strain gage technologies as applied to orthotropic composite materials are reviewed. The bonding procedures, transverse sensitivity effects, errors due to gage misalignment, and temperature compensation methods are addressed. Numerical examples are included where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain measurement errors.

  15. High Strain Rate Mechanical Properties of Glassy Polymers

    DTIC Science & Technology

    2012-07-25

    Force Materiel Command  United States Air Force  Eglin Air Force Base AFRL-RW-EG-TP-2012-008 High Strain Rate...TITLE AND SUBTITLE High Strain Rate Mechanical Properties of Glassy Polymers 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...1990s, a range of experimental data has been generated describing the response of glassy polymers to high strain rate loading in compression. More

  16. Potential pitfalls in the nuclear medicine imaging: Experimental models to evaluate the effect of natural products on the radiolabeling of blood constituents, bioavailability of radiopharmaceutical and on the survival of Escherichia coli strains submitted to the treatment with stannous ion

    NASA Astrophysics Data System (ADS)

    Soares, Scheila F.; Brito, Lavínia C.; Souza, Deise E.; Bernardo, Luciana C.; Oliveira, Joelma F.; Bernardo-Filho, Mario

    2006-12-01

    Single photon emission computed tomography (SPECT) allows studies of physiological or pathological processes. Red blood cells labeled with technetium-99m ( 99mTc-RBC) are used as a radiopharmaceutical in several evaluations. The radiolabeling efficiency and bioavailability of radiopharmaceuticals can be altered by natural/synthetic drugs and may induce pitfalls in the analysis of the nuclear medicine imaging. The labeling with 99mTc requires a reducing agent and stannous chloride (SnCl 2) is widely utilized. However, SnCl 2 presents a citotoxic and/or genotoxic potential in Escherichia coli ( E. coli) strains. The aim of this work was to evaluate the influence of aqueous extracts of Baccharis genistelloides (BG), Terminalia chebula (TC), Maytenus ilicifolia (MI), Cassia angustifolia (CA) and Equisetum arvense (EA) on (i) radiolabeling of blood constituents, (ii) bioavailability of sodium pertechnetate(Na 99mTcO 4) radiopharmaceutical, (iii) survival of E. coli. In vitro labeling of RBC was performed with blood ( Wistar rats) incubated with each extract, SnCl 2 and Na 99mTcO 4. Plasma (P) and blood cells (BC) were isolated, another aliquots precipitated and soluble (SF) and insoluble (IF) fractions isolated and counted. In the bioavailability of Na 99mTcO 4, Wistar rats were treated (7 days) with aqueous extract or with 0.9%NaCl, the radiopharmaceutical was administered, the animals sacrificed, the organs isolated, weighted and radioactivity counted. To evaluate the effect on the bacterial survival, E. coli was treated with: (a) SnCl 2; (b) 0.9% NaCl; (c) vegetal extract; or (d) SnCl 2 and vegetal extract. Radiolabeling efficiency showed a significantly decrease (ANOVA/Tukey post-test, p<0.05) after treatment with BG, TC, MI and CA extracts. The bioavailability results showed that the uptake of Na 99mTcO 4 was altered significantly (unpaired t-student test, p<0.05) in blood, lungs (CA/TC extracts), bone, heart, ovary (EA /TC), spleen, kidney (TC) , pancreas, thyroid

  17. Plane-strain tension tests on aluminum alloy sheet

    SciTech Connect

    Taha, F.; Hosford, W.; Graf, A.

    1995-04-01

    A simple way of making plane-strain tension tests on sheet specimens has been developed. This method was used to test sheets of aluminum alloy 2008 T4 and the results were analyzed in terms of a high exponent yield criterion and isotropic hardening. Experimentally measured forces agreed with those calculated from strain measurements using uniaxial tension test curves.

  18. Comparison of Commercial Real-Time Reverse Transcription-PCR Assays for Reliable, Early, and Rapid Detection of Heterologous Strains of Porcine Reproductive and Respiratory Syndrome Virus in Experimentally Infected or Noninfected Boars by Use of Different Sample Types

    PubMed Central

    Gerber, Priscilla F.; O'Neill, Kevin; Owolodun, Olajide; Wang, Chong; Harmon, Karen; Zhang, Jianqiang; Halbur, Patrick G.; Zhou, Lei; Meng, Xiang-Jin

    2013-01-01

    The aims of this study were to compare three commercial porcine reproductive and respiratory syndrome virus (PRRSV) real-time reverse transcription-PCR (RT-PCR) assays for detection of genetically diverse PRRSV isolates in serum, semen, blood swabs, and oral fluids collected from experimentally infected boars and to evaluate the effects of sample pooling. Six groups of three boars negative for PRRSV were each inoculated with one of six PRRSV isolates (sharing 55 to 99% nucleotide sequence identity in ORF5). Samples were collected on days −2, 1, 3, 5, 7, 14, and 21 postinoculation (p.i.) and tested by one of three commercially available real-time RT-PCR assays (VetMax from Applied Biosystems, Foster City, CA [abbreviated AB]; VetAlert from Tetracore, Rockville, MD [TC]; and AcuPig from AnDiaTec GmbH, Kornwestheim, Germany [AD]). At day 1 p.i., all assays detected at least one positive sample in each group. The highest detection rates were on days 3 and 5 p.i. Between days 1 and 7 p.i., serum samples had the highest detection rate (90%) with 100% agreement between tests, followed by blood swabs (kappa value of 0.97) and semen (kappa value of 0.80). Oral fluids had the lowest detection rates (AB, 55%; TC, 41%; AD, 46%) and the highest disagreement between kits (kappa value of 0.63). Pools of five samples did not reduce the detection rates if there was one positive sample with a large amount (cycle threshold, <30) of viral RNA in the pool. Serum and blood swab samples had shorter turnaround times for RNA extraction. The AB assay had a 1.6-times-shorter PCR time. In summary, serum and blood swabs had the best performance with highest detection rates and agreement between assays and the shortest turnaround times. PMID:23224085

  19. CD19 LYMPHOCYTE PROLIFERATION INDUCED BY Bifidobacterium animalis subsp. lactis IN C57BL/6 MICE EXPERIMENTALLY INFECTED WITH Toxoplasma gondii

    PubMed Central

    RIBEIRO, Claudia de Mello; ZORGI, Nahiara Esteves; MEIRELES, Luciana Regina; GARCIA, João Luis; de ANDRADE, Heitor Franco

    2016-01-01

    Toxoplasmosis is frequently acquired through the oral route by the ingestion of cysts or oocysts of Toxoplasma gondii. Once ingested, the parasites penetrate the intestinal epithelial cells and rapidly disseminate to all organs in the host. During T. gondii infection, the intestinal microbiota plays an important role in stimulating a protective immune response against the parasite. In this sense the use of probiotics is worthy of note since they are live microorganisms that have beneficial effects on the host through stimulation of the immune response that can be important in the control of T. gondii proliferation and dissemination in the host. In the present study, the action of the probiotic Bifidobacterium animalis subsp. lactis was investigated in C57BL/6 mice infected with oocysts of ME49 strain of T. gondii. The probiotic had an immunomodulatory action, inducing CD19 lymphocyte proliferation and consequently increasing anti-T. gondii antibody level.Bifidobacterium animalis subsp. lactisprovided protection in supplemented mice, compared to the control group. In addition, supplemented animals had milder inflammatory process in the small intestine, indicating that the probiotic protects the intestinal mucosa during infection with T. gondii. It was concluded that the probioticB. animalis subsp. lactis induces humoral immune response capable of providing protection against T. gondii infection. PMID:27074320

  20. CD19 LYMPHOCYTE PROLIFERATION INDUCED BY Bifidobacterium animalis subsp. lactis IN C57BL/6 MICE EXPERIMENTALLY INFECTED WITH Toxoplasma gondii.

    PubMed

    Ribeiro, Claudia de Mello; Zorgi, Nahiara Esteves; Meireles, Luciana Regina; Garcia, João Luis; Andrade Junior, Heitor Franco de

    2016-01-01

    Toxoplasmosis is frequently acquired through the oral route by the ingestion of cysts or oocysts of Toxoplasma gondii. Once ingested, the parasites penetrate the intestinal epithelial cells and rapidly disseminate to all organs in the host. During T. gondii infection, the intestinal microbiota plays an important role in stimulating a protective immune response against the parasite. In this sense the use of probiotics is worthy of note since they are live microorganisms that have beneficial effects on the host through stimulation of the immune response that can be important in the control of T. gondii proliferation and dissemination in the host. In the present study, the action of the probiotic Bifidobacterium animalis subsp. lactis was investigated in C57BL/6 mice infected with oocysts of ME49 strain of T. gondii. The probiotic had an immunomodulatory action, inducing CD19 lymphocyte proliferation and consequently increasing anti-T. gondii antibody level. Bifidobacterium animalis subsp. lactis provided protection in supplemented mice, compared to the control group. In addition, supplemented animals had milder inflammatory process in the small intestine, indicating that the probiotic protects the intestinal mucosa during infection with T. gondii. It was concluded that the probiotic B. animalis subsp. lactis induces humoral immune response capable of providing protection against T. gondii infection.

  1. Relationship between magnetic susceptibility and strain in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham; Alford, Craig

    1987-02-01

    Under experimental conditions of 1.5 kbar confining pressure and at a strain-rate of 5 × 10 -6 sec -1 at room temperature the principal directions of magnetic susceptibility of a dry, synthetic, magnetite-bearing sandstone rotate toward principal strain directions. The rotation is faster than that expected from rotation of a line in homogeneous strain. Fluid pressures of 200 or 700 bars do not appear to affect the development of anisotropy of susceptibility. The change in bulk anisotropy shows a power law correlation with strain ratio where the initial susceptibility ellipsoid was nearly coaxial with the bulk strain axes during the experiment. More generally, in those situations, as well as ones in which the initial susceptibility ellipsoid was strongly inclined to the bulk strain axes there exists a common matrix M which relates the initial susceptibility tensor kij, the final susceptibility tensor k' ij and the strain tensor eij: eijk' ij = Mk' ij

  2. Tuning Surface Properties of Low Dimensional Materials via Strain Engineering.

    PubMed

    Yang, Shengchun; Liu, Fuzhu; Wu, Chao; Yang, Sen

    2016-08-01

    The promising and versatile applications of low dimensional materials are largely due to their surface properties, which along with their underlying electronic structures have been well studied. However, these materials may not be directly useful for applications requiring properties other than their natal ones. In recent years, strain has been shown to be an additionally useful handle to tune the physical and chemical properties of materials by changing their geometric and electronic structures. The strategies for producing strain are summarized. Then, the electronic structure of quasi-two dimensional layered non-metallic materials (e.g., graphene, MX2, BP, Ge nanosheets) under strain are discussed. Later, the strain effects on catalytic properties of metal-catalyst loaded with strain are focused on. Both experimental and computational perspectives for dealing with strained systems are covered. Finally, an outlook on engineering surface properties utilizing strain is provided. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Joint Actinide Shock Physics Experimental Research - JASPER

    ScienceCinema

    None

    2016-07-12

    Commonly known as JASPER the Joint Actinide Shock Physics Experimental Research facility is a two stage light gas gun used to study the behavior of plutonium and other materials under high pressures, temperatures, and strain rates.

  4. Joint Actinide Shock Physics Experimental Research - JASPER

    SciTech Connect

    2014-10-31

    Commonly known as JASPER the Joint Actinide Shock Physics Experimental Research facility is a two stage light gas gun used to study the behavior of plutonium and other materials under high pressures, temperatures, and strain rates.

  5. Strain effects on oxygen transport in tetragonal zirconium dioxide

    SciTech Connect

    Xian-Ming Bai; Yongfeng Zhang; Michael R. Tonks

    2013-11-01

    Temperature accelerated dynamics and molecular dynamics simulations are used to investigate the strain effects on oxygen interstitial and vacancy migration in tetragonal zirconium dioxide. At zero external strain, the anisotropic migration mechanisms of oxygen defects are characterized. At non-zero strains, both the crystal structure and defect migration barriers are modified by strain. Under compressive strains, the defect migration barrier increases with the increasing strain for both interstitials and vacancies. The crystal structure transforms from a tetragonal to a nearly cubic fluorite structure. Accordingly, the defect migration becomes nearly isotropic. Under dilative strains, the migration barrier first decreases then increases with increasing strain for both types of defects. The tetragonal phase transforms to a lower symmetry structure that is close to the orthorhombic phase. In turn, the defect migration becomes highly anisotropic. Under both compressive and dilative strains, interstitials respond to strain more strongly than vacancies. At small dilative strains, an oxygen interstitial has comparable diffusivity to a vacancy, suggesting that both types of defects can contribute to oxygen transport, if they are present. Although currently no previous result is available to validate oxygen interstitial diffusion behavior, the trend of strain effects on oxygen vacancy diffusion is in good agreement with available experimental and theoretical studies in the literature.

  6. Heat strain in cold.

    PubMed

    Rintamäki, Hannu; Rissanen, Sirkka

    2006-07-01

    In spite of increased environmental cold stress, heat strain is possible also in a cold environment. The body heat balance depends on three factors: environmental thermal conditions, metabolic heat production and thermal insulation of clothing and other protective garments. As physical exercise may increase metabolic heat production from rest values by ten times or even more, the required thermal insulation of clothing may vary accordingly. However, in most outdoor work, and often in indoor cold work, too, the thermal insulation of clothing is impractical, difficult or impossible to adjust according to the changes in physical activity. This is especially true with whole body covering garments like chemical protective clothing. As a result of this imbalance, heat strain may develop. In cold all the signs of heat strain (core temperature above 38 degrees C, warm or hot thermal sensations, increased cutaneous circulation and sweating) may not be present at the same time. Heat strain in cold may be whole body heat strain or related only to torso or core temperature. Together with heat strain in torso or body core, there can be at the same time even cold strain in peripheral parts and/or superficial layers of the body. In cold environment both the preservation of insulation and facilitation of heat loss are important. Development of clothing design is still needed to allow easy adjustments of thermal insulation.

  7. Thin film strain transducer

    NASA Astrophysics Data System (ADS)

    Rand, J. L.

    1981-01-01

    Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

  8. Power-dependent Raman analysis of highly strained Si nanobridges.

    PubMed

    Süess, M J; Minamisawa, R A; Geiger, R; Bourdelle, K K; Sigg, H; Spolenak, R

    2014-03-12

    Strain analysis of complex three-dimensional nanobridges conducted via Raman spectroscopy requires careful experimentation and data analysis supported by simulations. A method combining micro-Raman spectroscopy with finite element analysis is presented, enabling a detailed understanding of strain-sensitive Raman data measured on Si nanobridges. Power-dependent measurements are required to account for the a priori unknown scattering efficiency related to size and geometry. The experimental data is used to assess the validity of previously published phonon deformation potentials.

  9. Experimental challenge of chicken vaccinated with commercially available H5 vaccines reveals loss of protection to some highly pathogenic avian influenza H5N1 strains circulating in Hong Kong/China.

    PubMed

    Connie Leung, Y H; Luk, Geraldine; Sia, Sin-Fun; Wu, Yu-On; Ho, Chuk-Kwan; Chow, Kai-Chi; Tang, Shing-Chun; Guan, Yi; Malik Peiris, J S

    2013-08-02

    Highly pathogenic avian influenza (HPAI) H5N1 virus continues to circulate in poultry in Asia and Africa posing a threat to both public and animal health. Vaccination, used as an adjunct to improved bio-security and stamping-out policies, contributed to protecting poultry in Hong Kong from HPAI H5N1 infection in 2004-2008 although the virus was repeatedly detected in dead wild birds. The detection of clade 2.3.4 H5N1 viruses in poultry markets and a farm in Hong Kong in 2008 raised the question whether this virus has changed to evade protection from the H5 vaccines in use. We tested the efficacy of three commercial vaccines (Nobilis, Poulvac and Harbin Re-5 vaccine) in specific pathogen free white leghorn chickens against a challenge with A/chicken/Hong Kong/8825-2/2008 (clade 2.3.4) isolated from vaccinated poultry in Hong Kong and A/chicken/Hong Kong/782/2009 (clade 2.3.2). Harbin Re5 vaccine provided the best, albeit not complete protection against challenge with the clade 2.3.4 virus. All three vaccines provided good protection from death and significantly reduced virus shedding following challenge with the clade 2.3.2 virus. Only Harbin Re-5 was able to completely protect chickens from virus shedding as well as mortality. Sera from vaccinated chickens had lower geometric hemagglutination inhibition titers against A/chicken/Hong Kong/8825-2/08, as compared to two other clade 2.3.4 and one clade 0 virus. Alignment of amino-acid sequences of the haemagglutinin of A/chicken/Hong Kong/8825-2/08 and the other H5 viruses revealed several mutations in positions including 69, 71, 83, 95, 133,140, 162, 183, 189, 194 and 270 (H5 numbering) which may correlate with loss of vaccine protection. Our results indicated that the tested HPAI H5N1 (2.3.4) virus has undergone antigenic changes that allow it to evade immunity from poultry vaccines. This highlights the need for continued surveillance and monitoring of vaccine induced immunity, with experimental vaccine challenge

  10. Computer modelling of bone's adaptation: the role of normal strain, shear strain and fluid flow.

    PubMed

    Tiwari, Abhishek Kumar; Prasad, Jitendra

    2017-04-01

    Bone loss is a serious health problem. In vivo studies have found that mechanical stimulation may inhibit bone loss as elevated strain in bone induces osteogenesis, i.e. new bone formation. However, the exact relationship between mechanical environment and osteogenesis is less clear. Normal strain is considered as a prime stimulus of osteogenic activity; however, there are some instances in the literature where osteogenesis is observed in the vicinity of minimal normal strain, specifically near the neutral axis of bending in long bones. It suggests that osteogenesis may also be induced by other or secondary components of mechanical environment such as shear strain or canalicular fluid flow. As it is evident from the literature, shear strain and fluid flow can be potent stimuli of osteogenesis. This study presents a computational model to investigate the roles of these stimuli in bone adaptation. The model assumes that bone formation rate is roughly proportional to the normal, shear and fluid shear strain energy density above their osteogenic thresholds. In vivo osteogenesis due to cyclic cantilever bending of a murine tibia has been simulated. The model predicts results close to experimental findings when normal strain, and shear strain or fluid shear were combined. This study also gives a new perspective on the relation between osteogenic potential of micro-level fluid shear and that of macro-level bending shear. Attempts to establish such relations among the components of mechanical environment and corresponding osteogenesis may ultimately aid in the development of effective approaches to mitigating bone loss.

  11. Viscoelastic strain-energy hinge for solar array deployment

    NASA Astrophysics Data System (ADS)

    Kwak, Moon K.; Ra, Wan-Kyu; Yoon, Kwang J.

    1999-07-01

    This paper is concerned with the viscoelastic strain-energy hinge for solar array deployment. The original strain-energy hinge proposed by TRW for solar array deployment was made of strip measures. Due to its structural simplicity, the strain-energy hinge has been considered as an alternative to the torsional spring type deployment mechanism. However, theoretical modeling of the strain-energy hinge is extremely difficult because of its nonlinear pre- and post-buckling dynamic behavior. To investigate its dynamic characteristics, series of buckling and deployment tests on a single strain-energy hinge and a solar array structure equipped with strain-energy hinge have been conducted. The deployment test results show that there remain residual vibrations after deployment, which are resulted from the rapid deployment and the bending flexibility of the strain- energy hinge. We propose the use of viscoelastic material embedded between the layers of the strip measure to increase the passive damping. It results in less residual vibrations and smooth deployment. Experimental results show that viscoelastic strain-energy hinge ins superior to the ordinary strain-energy hinge in deployments. Based on the experiments on the single strain-energy hinge, an equivalent 1D torsional spring model is proposed. Simulation results based on the equivalent model are fairly in good agreement with experimental results.

  12. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  13. Genetics of experimental hypertension.

    PubMed

    Dominiczak, A F; Clark, J S; Jeffs, B; Anderson, N H; Negrin, C D; Lee, W K; Brosnan, M J

    1998-12-01

    Experimental models of genetic hypertension are used to develop paradigms to study human essential hypertension while removing some of the complexity inherent in the study of human subjects. Since 1991 several quantitative trait loci responsible for blood pressure regulation have been identified in various rat crosses. More recently, a series of interesting quantitative trait loci influencing cardiac hypertrophy, stroke, metabolic syndrome and renal damage has also been described. It is recognized that the identification of large chromosomal regions containing a quantitative trait locus is only a first step towards gene identification. The next step is the production of congenic strains and substrains to confirm the existence of the quantitative trait locus and to narrow down the chromosomal region of interest. Several congenic strains have already been produced, with further refinement of the methodology currently in progress. The ultimate goal is to achieve positional cloning of the causal gene, a task which has so far been elusive. There are several areas of cross-fertilization between experimental and human genetics of hypertension, with a successful transfer of two loci directly from rats to humans and with new pharmacogenetic approaches which may be utilized in both experimental and clinical settings.

  14. Experimental evolution.

    PubMed

    Kawecki, Tadeusz J; Lenski, Richard E; Ebert, Dieter; Hollis, Brian; Olivieri, Isabelle; Whitlock, Michael C

    2012-10-01

    Experimental evolution is the study of evolutionary processes occurring in experimental populations in response to conditions imposed by the experimenter. This research approach is increasingly used to study adaptation, estimate evolutionary parameters, and test diverse evolutionary hypotheses. Long applied in vaccine development, experimental evolution also finds new applications in biotechnology. Recent technological developments provide a path towards detailed understanding of the genomic and molecular basis of experimental evolutionary change, while new findings raise new questions that can be addressed with this approach. However, experimental evolution has important limitations, and the interpretation of results is subject to caveats resulting from small population sizes, limited timescales, the simplified nature of laboratory environments, and, in some cases, the potential to misinterpret the selective forces and other processes at work. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Experimental design and husbandry.

    PubMed

    Festing, M F

    1997-01-01

    Rodent gerontology experiments should be carefully designed and correctly analyzed so as to provide the maximum amount of information for the minimum amount of work. There are five criteria for a "good" experimental design. These are applicable both to in vivo and in vitro experiments: (1) The experiment should be unbiased so that it is possible to make a true comparison between treatment groups in the knowledge that no one group has a more favorable "environment." (2) The experiment should have high precision so that if there is a true treatment effect there will be a good chance of detecting it. This is obtained by selecting uniform material such as isogenic strains, which are free of pathogenic microorganisms, and by using randomized block experimental designs. It can also be increased by increasing the number of observations. However, increasing the size of the experiment beyond a certain point will only marginally increase precision. (3) The experiment should have a wide range of applicability so it should be designed to explore the sensitivity of the observed experimental treatment effect to other variables such as the strain, sex, diet, husbandry, and age of the animals. With in vitro data, variables such as media composition and incubation times may also be important. The importance of such variables can often be evaluated efficiently using "factorial" experimental designs, without any substantial increase in the overall number of animals. (4) The experiment should be simple so that there is little chance of groups becoming muddled. Generally, formal experimental designs that are planned before the work starts should be used. (5) The experiment should provide the ability to calculate uncertainty. In other words, it should be capable of being statistically analyzed so that the level of confidence in the results can be quantified.

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