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Sample records for field strains reported

  1. Piezoelectric field in strained GaAs.

    SciTech Connect

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

  2. First Report of Avian Metapneumovirus Subtype B Field Strain in a Romanian Broiler Flock During an Outbreak of Respiratory Disease.

    PubMed

    Franzo, Giovanni; Tucciarone, Claudia Maria; Enache, Mirel; Bejan, Violeta; Ramon, Gema; Koutoulis, Konstantinos C; Cecchinato, Mattia

    2017-06-01

    Avian metapneumovirus (aMPV) represents one of the most prevalent diseases of turkey, especially in combination with other pathogens, and its frequency is also increasing among chickens. Despite this evidence, epidemiologic data are poor and scattered, severely preventing control of the disease even in highly developed areas such as Europe. In the present study, the detection and characterization of an aMPV subtype B strain circulating in a vaccinated but symptomatic Romanian broiler flock is reported for the first time. The phylogenetic analysis based on the partial G gene sequence demonstrates the close relationship of the Romanian virus with a group of recently emerged Italian field strains for which vaccine-induced protection was experimentally proven to be partial. These preliminary results allow us to hypothesize the spreading of vaccine-escaping aMPV subtype B strains through Europe and, consequently, dictate the carrying out of a more systematic survey to confirm this theory and enforce adequate countermeasures.

  3. Characterization of BoHV-5 field strains circulation and report of transient specific subtype of bovine herpesvirus 5 in Argentina

    PubMed Central

    2011-01-01

    Background Bovine herpesvirus 5 (BoHV-5) is a member of the subfamily Alphaherpesvirinae responsible for meningo-encephalitis in young cattle. The first case of bovine meningo-encephalitis associated with a herpesvirus infection was reported in Australia. The current geographical distribution of BoHV-5 infection is mainly restricted to South America, especially Brazil and Argentina. Outbreaks of BoHV-5 are regularly observed in Argentina suggesting the circulation of the virus in the bovine population. Results Seventeen field strains of BoHV-5 isolated from 1984 to now were confirmed by differential PCR and subjected to restriction endonuclease analysis (REA). Viral DNA was cleaved with BstEII which allows the differentiation among subtypes a, b and non a, non b. According to the REA with BstEII, only one field strain showed a pattern similar to the Argentinean A663 strain (prototype of BoHV-5b). All other isolates showed a clear pattern similar to the Australian N569 strain (prototype of BoHV-5a) consistent with the subtypes observed in Brazil, the other South-American country where BoHV-5 is known to be prevalent. The genomic region of subtype b responsible for the distinct pattern was determined and amplified by PCR; specifically a point mutation was identified in glycoprotein B gene, on the BstEII restriction site, which generates the profile specific of BoHV-5b. Conclusions This is the first report of circulation of BoHV-5a in Argentina as the prevailing subtype. Therefore the circulation of BoHV-5b was restricted to a few years in Argentina, speculating that this subtype was not able to be maintained in the bovine population. The mutation in the gB gene is associated with the difference in the restriction patterns between subtypes "a" and "b". PMID:21299866

  4. Strain sensors for high field pulse magnets

    SciTech Connect

    Martinez, Christian; Zheng, Yan; Easton, Daniel; Farinholt, Kevin M; Park, Gyuhae

    2009-01-01

    In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Three operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.

  5. Motion Driven by Strain Gradient Fields

    PubMed Central

    Wang, Chao; Chen, Shaohua

    2015-01-01

    A new driving mechanism for direction-controlled motion of nano-scale objects is proposed, based on a model of stretching a graphene strip linked to a rigid base with linear springs of identical stiffness. We find that the potential energy difference induced by the strain gradient field in the graphene strip substrate can generate sufficient force to overcome the static and kinetic friction forces between the nano-flake and the strip substrate, resulting in the nanoscale flake motion in the direction of gradient reduction. The dynamics of the nano-flake can be manipulated by tuning the stiffness of linear springs, stretching velocity and the flake size. This fundamental law of directional motion induced by strain gradient could be very useful for promising designs of nanoscale manipulation, transportation and smart surfaces. PMID:26323603

  6. Field Performance of a Genetically Engineered Strain of Pink Bollworm

    PubMed Central

    Simmons, Gregory S.; McKemey, Andrew R.; Morrison, Neil I.; O'Connell, Sinead; Tabashnik, Bruce E.; Claus, John; Fu, Guoliang; Tang, Guolei; Sledge, Mickey; Walker, Adam S.; Phillips, Caroline E.; Miller, Ernie D.; Rose, Robert I.; Staten, Robert T.; Donnelly, Christl A.; Alphey, Luke

    2011-01-01

    Pest insects harm crops, livestock and human health, either directly or by acting as vectors of disease. The Sterile Insect Technique (SIT) – mass-release of sterile insects to mate with, and thereby control, their wild counterparts – has been used successfully for decades to control several pest species, including pink bollworm, a lepidopteran pest of cotton. Although it has been suggested that genetic engineering of pest insects provides potential improvements, there is uncertainty regarding its impact on their field performance. Discrimination between released and wild moths caught in monitoring traps is essential for estimating wild population levels. To address concerns about the reliability of current marking methods, we developed a genetically engineered strain of pink bollworm with a heritable fluorescent marker, to improve discrimination of sterile from wild moths. Here, we report the results of field trials showing that this engineered strain performed well under field conditions. Our data show that attributes critical to SIT in the field – ability to find a mate and to initiate copulation, as well as dispersal and persistence in the release area – were comparable between the genetically engineered strain and a standard strain. To our knowledge, these represent the first open-field experiments with a genetically engineered insect. The results described here provide encouragement for the genetic control of insect pests. PMID:21931649

  7. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Annual report, March 1996--March 1997

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Groshong, R.H.

    1997-08-01

    Gilbertown Field is the oldest oil field in Alabama and produces oil from chalk of the Upper Cretaceous Selma Group and from sandstone of the Eutaw Formation along the southern margin of the Gilbertown fault system. Most of the field has been in primary recovery since establishment, but production has declined to marginally economic levels. This investigation applies advanced geologic concepts designed to aid implementation of improved recovery programs. The Gilbertown fault system is detached at the base of Jurassic salt. The fault system began forming as a half graben and evolved in to a full graben by the Late Cretaceous. Conventional trapping mechanisms are effective in Eutaw sandstone, whereas oil in Selma chalk is trapped in faults and fault-related fractures. Burial modeling establishes that the subsidence history of the Gilbertown area is typical of extensional basins and includes a major component of sediment loading and compaction. Surface mapping and fracture analysis indicate that faults offset strata as young as Miocene and that joints may be related to regional uplift postdating fault movement. Preliminary balanced structural models of the Gilbertown fault system indicate that synsedimentary growth factors need to be incorporated into the basic equations of area balance to model strain and predict fractures in Selma and Eutaw reservoirs.

  8. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama. Final report, March 1996--September 1998

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.; Groshong, R.H.; Jin, G.

    1998-12-01

    This project was designed to analyze the structure of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas to suggest ways in which oil recovery can be improved. The Eutaw Formation comprises 7 major flow units and is dominated by low-resistivity, low-contrast play that is difficult to characterize quantitatively. Selma chalk produces strictly from fault-related fractures that were mineralized as warm fluid migrated from deep sources. Resistivity, dipmeter, and fracture identification logs corroborate that deformation is concentrated in the hanging-wall drag zones. New area balancing techniques were developed to characterize growth strata and confirm that strain is concentrated in hanging-wall drag zones. Curvature analysis indicates that the faults contain numerous fault bends that influence fracture distribution. Eutaw oil is produced strictly from footwall uplifts, whereas Selma oil is produced from fault-related fractures. Clay smear and mineralization may be significant trapping mechanisms in the Eutaw Formation. The critical seal for Selma reservoirs, by contrast, is where Tertiary clay in the hanging wall is juxtaposed with poorly fractured Selma chalk in the footwall. Gilbertown Field can be revitalized by infill drilling and recompletion of existing wells. Directional drilling may be a viable technique for recovering untapped oil from Selma chalk. Revitalization is now underway, and the first new production wells since 1985 are being drilled in the western part of the field.

  9. Geodetic strain-rate field of Iberia

    NASA Astrophysics Data System (ADS)

    Fernandes, R. M.; Bos, M. S.; Apolinário, J. P.; Dias, N. A.; Neves, M. L.; Miranda, J. M.

    2013-12-01

    Currently, the number of available GNSS (Global Navigation Satellite System) CORS (Continuous Operating Reference Stations) in Iberia reaches almost 300 stations distributed over several national and regional networks. The majority of these stations were installed for surveying and cadaster applications (RTK networks). Although the required stability of the monuments for such applications is lower than for geodynamic purposes, we demonstrate, by investigating the level and type of noise, that the majority of these stations provide reliable information about their secular tectonic motions. The large number and relative uniform distribution over the entire Iberia also facilitate to identify stations showing abnormal and unexplained artifacts in their time-series. We computed the uniform velocity field using the stations with observations spanning 3 years or longer (~100 stations). Most of Iberia shows no relative motion with respect to Eurasia - their residuals are below the computed uncertainty of the velocity. However, the southern part of Iberia is affected by the convergence of Nubia towards Iberia. The clockwise rotation of the southern part of the Peninsula is clearly observed with an increment of the motion towards west until the Gibraltar area. This is also clearly observed in the derived strain rate field, which shows significant deformation rates in this region. The residual westward motion is still evident in the south of Portugal even if the magnitude is smaller - suggesting this area is already more stable with respect to the plate boundary. This work is carried out in the framework of the European Project EPOS and Portuguese Project SMOG (PTDC/CTE-ATM/119922/2010).

  10. Thermographic phosphor strain measurements. Final report

    SciTech Connect

    Allison, S.W.; Capps, G.J.; Smith, D.B.; Cates, M.R.; Gleason, J.; Turley, W.D.

    1994-05-01

    This report describes the first phase of research aimed at developing a high-temperature strain gauge for power equipment use based on materials whose fluorescence characteristics are affected by strain. In electric power generating plants, the combined effect of temperature and strain on equipment and structures is a critical factor in safe, efficient operation and component lifetime. For the first part of this project, the pressure responses of phosphor and crystalline materials were surveyed. Next, pressure measurements on some promising materials, YVO{sub 4}:Dy and Gd{sub 2}O{sub 2}S:Tb, were performed. The latter phosphor appears to exhibit the greatest change with pressure. Its fluorescence lifetime decreases by a factor of 10 with pressure increase of 20 kbar. In a strain test configuration, a tapered sapphire rod compressed a similar phosphor material, La{sub 2}O{sub 2}S:Eu. The intensity level increased, as expected for this material, with compression. Both of the oxysulfide materials possess potential for use in an optical strain gauge for temperatures up to at least 300{degrees}C. It is suggested that a mixture of these two materials may be a useful way to obtain the maximum pressure or strain sensitivity.

  11. Volume strain within the Geysers geothermal field

    SciTech Connect

    Mossop, Antony; Segall, Paul

    1999-12-10

    During the 1970s and 1980s. The Geysers geothermal region was rapidly developed as a site of geothermal power production. The likelihood that this could cause significant strain within the reservoir, with corresponding surface displacements, led to a series of deformation monitoring surveys. In 1973, 1975, 1977, and 1980, The Geysers region was surveyed using first-order, class I, spirit leveling. In 1994, 1995, and 1996, many of the leveling control monuments were resurveyed using high-precision Global Positioning System receivers. The two survey methods are reconciled using the GEOID96 geoid model. The displacements are inverted to determine volume strain within the reservoir. For the period 1980-1994, peak volume strains in excess of 5x10{sup -4} are imaged. There is an excellent correlation between the observed changes in reservoir steam pressures and the imaged volume strain. If reservoir pressure changes are inducing volume strain, then the reservoir quasi-static bulk modulus K must be <4.6x10{sup 9} Pa. However, seismic velocities indicate a much stiffer reservoir with K=3.4x10{sup 10} Pa. This apparent discrepancy is shown to be consistent with predicted frequency dependence in K for fractured and water-saturated rock. Inversion of surface deformation data therefore appears to be a powerful method for imaging pressure change within the body of the reservoir. Correlation between induced seismicity at The Geysers and volume strain is observed. However, earthquake distribution does not appear to have a simple relationship with volume strain rate. (c) 1999 American Geophysical Union.

  12. Strain engineering of graphene nanoribbons: pseudomagnetic versus external magnetic fields

    NASA Astrophysics Data System (ADS)

    Prabhakar, Sanjay; Melnik, Roderick; Bonilla, Luis

    2017-05-01

    Bandgap opening due to strain engineering is a key architect for making graphene's optoelectronic, straintronic, and spintronic devices. We study the bandgap opening due to strain induced ripple waves and investigate the interplay between pseudomagnetic fields and externally applied magnetic fields on the band structures and spin relaxation in graphene nanoribbons (GNRs). We show that electron-hole bands of GNRs are highly influenced (i.e. level crossing of the bands are possible) by coupling two combined effects: pseudomagnetic fields (PMF) originating from strain tensor and external magnetic fields. In particular, we show that the tuning of the spin-splitting band extends to large externally applied magnetic fields with increasing values of pseudomagnetic fields. Level crossings of the bands in strained GNRs can also be observed due to the interplay between pseudomagnetic fields and externally applied magnetic fields. We also investigate the influence of this interplay on the electromagnetic field mediated spin relaxation mechanism in GNRs. In particular, we show that the spin hot spot can be observed at approximately B = 65 T (the externally applied magnetic field) and B0 = 53 T (the magnitude of induced pseudomagnetic field due to ripple waves) which may not be considered as an ideal location for the design of straintronic devices. Our analysis might be used for tuning the bandgaps in strained GNRs and utilized to design the optoelectronic devices for straintronic applications.

  13. Imaging 3D strain field monitoring during hydraulic fracturing processes

    NASA Astrophysics Data System (ADS)

    Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong; Li, Shuo; Lu, Guanyi; Ames, Brandon C.; Zolfaghari, Navid; Bunger, Andrew P.; Li, Ming-Jun; Chen, Kevin P.

    2016-05-01

    In this paper, we present a distributed fiber optic sensing scheme to study 3D strain fields inside concrete cubes during hydraulic fracturing process. Optical fibers embedded in concrete were used to monitor 3D strain field build-up with external hydraulic pressures. High spatial resolution strain fields were interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry. The fiber optics sensor scheme presented in this paper provides scientists and engineers a unique laboratory tool to understand the hydraulic fracturing processes in various rock formations and its impacts to environments.

  14. Strain rate and stress field in Switzerland

    NASA Astrophysics Data System (ADS)

    Houlié, Nicolas; Woessner, Jochen; Giardini, Domenico; Rothacher, Markus

    2016-04-01

    In this study we test whether the surface deformation and the seismic activity are in agreement in terms of seismic moment release and stress/strain orientations within the territory of Switzerland. We find that for most of the country, the stress released (~2.0 10E11 N·m/yr) is consistent with the lithosphere deformation (<5 10E-8 /yr) constrained using the Global Positioning System (GPS). South of the Alpine front, we note that surface strain rates displays few agreement with long-term (and deep) deformation of the upper mantle. In this area, we propose that shear strain is being distributed in the upper crust as a result of the clockwise rotation of the Adria plate. For three regions (Basel, Swiss Jura and Ticino), we find that seismic current activity and surface deformation not to be in agreement. In the Basel area, deep seismicity exists while surface deformation is absent. This situation contrasts to what is found in the Ticino and the Swiss Jura, where seismic activity is close to absent but surface deformation is detected (~2 10E-8 /yr). While the surface deformation and seismic activity is inconsistent for the Ticino, we find them to comply in the Valais region where MW≥6 events are historically documented. Our comparison implies that the Ticino faces the potential of damaging earthquakes every hundred to few hundred years.

  15. Transport in Strained Graphene with Applied Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Aguilera-Servin, Juan; Bockrath, Marc

    2014-03-01

    Strain in graphene layers produces synthetic gauge fields that may be used to modify the properties of its electron system. We study single layers of graphene transferred over Ti/Au electrical contacts on oxidized Si wafers with etched triangular holes in the oxide. The layers are strained by applying pressure either electrostatically from a gate voltage or hydrostatically from an external inert gas. We investigate electronic transport in this suspended variable-strain graphene system under applied magnetic fields and find that the device conductance is modulated by the external pressure as well as by the Hall effect. We will discuss our latest results.

  16. Mapping and load response of overload strain fields: Synchrotron X-ray measurements

    SciTech Connect

    Shukla, V; Jisrawi, N M; Sadangi, R K; Pao, P S; Horvath, K; Sadananda, K; Ignatov, A; Skaritka, J; Tsakalakos, T

    2009-02-05

    High energy synchrotron X-ray diffraction measurements have been performed to provide quantitative microscopic guidance for modeling of fatigue crack growth. Specifically we report local strain mapping, along with in situ loading strain response, results on 4140 steel fatigue specimens exhibiting the crack growth retardation 'overload effect'. Detailed, 2D, {epsilon}{gamma}{gamma}-strain field mapping shows that a single overload (OL) cycle creates a compressive strain field extending millimeters above and below the crack plane. The OL strain field structures are shown to persist after the crack tip has grown well beyond the OL position. The specimen exhibiting the maximal crack growth rate retardation following overload exhibits a tensile residual strain region at the crack tip. Strain field results, on in situ tensile loaded specimens, show a striking critical threshold load, F{sub c}, phenomenon in their strain response. At loads below F{sub c} the strain response is dominated by a rapid suppression of the compressive OL feature with modest response at the crack tip. At loads above F{sub c} the strain response at the OL position terminates and the response at the crack tip becomes large. This threshold load response behavior is shown to exhibit lower F{sub c} values, and dramatically enhanced rates of strain change with load as the crack tip propagates farther beyond the OL position. The OL strain feature behind the crack tip also is shown to be suppressed by removing the opposing crack faces via an electron discharge cut passing through the crack tip. Finally unique 2D strain field mapping (imaging) results, through the depth of the specimen, of the fatigue crack front and the OL feature in the wake are also presented.

  17. A geometric nonlinear degenerated shell element using a mixed formulation with independently assumed strain fields. Final Report; Ph.D. Thesis, 1989

    NASA Technical Reports Server (NTRS)

    Graf, Wiley E.

    1991-01-01

    A mixed formulation is chosen to overcome deficiencies of the standard displacement-based shell model. Element development is traced from the incremental variational principle on through to the final set of equilibrium equations. Particular attention is paid to developing specific guidelines for selecting the optimal set of strain parameters. A discussion of constraint index concepts and their predictive capability related to locking is included. Performance characteristics of the elements are assessed in a wide variety of linear and nonlinear plate/shell problems. Despite limiting the study to geometric nonlinear analysis, a substantial amount of additional insight concerning the finite element modeling of thin plate/shell structures is provided. For example, in nonlinear analysis, given the same mesh and load step size, mixed elements converge in fewer iterations than equivalent displacement-based models. It is also demonstrated that, in mixed formulations, lower order elements are preferred. Additionally, meshes used to obtain accurate linear solutions do not necessarily converge to the correct nonlinear solution. Finally, a new form of locking was identified associated with employing elements designed for biaxial bending in uniaxial bending applications.

  18. A geometric nonlinear degenerated shell element using a mixed formulation with independently assumed strain fields. Final Report; Ph.D. Thesis, 1989

    NASA Technical Reports Server (NTRS)

    Graf, Wiley E.

    1991-01-01

    A mixed formulation is chosen to overcome deficiencies of the standard displacement-based shell model. Element development is traced from the incremental variational principle on through to the final set of equilibrium equations. Particular attention is paid to developing specific guidelines for selecting the optimal set of strain parameters. A discussion of constraint index concepts and their predictive capability related to locking is included. Performance characteristics of the elements are assessed in a wide variety of linear and nonlinear plate/shell problems. Despite limiting the study to geometric nonlinear analysis, a substantial amount of additional insight concerning the finite element modeling of thin plate/shell structures is provided. For example, in nonlinear analysis, given the same mesh and load step size, mixed elements converge in fewer iterations than equivalent displacement-based models. It is also demonstrated that, in mixed formulations, lower order elements are preferred. Additionally, meshes used to obtain accurate linear solutions do not necessarily converge to the correct nonlinear solution. Finally, a new form of locking was identified associated with employing elements designed for biaxial bending in uniaxial bending applications.

  19. MLVA typing of Mycoplasma hyopneumoniae bacterins and field strains

    PubMed Central

    Tamiozzo, P.; Zamora, R.; Lucchesi, P. M. A.; Estanguet, A.; Parada, J.; Carranza, A.; Camacho, P.; Ambrogi, A.

    2015-01-01

    Because of the lack of information about both the genetic characteristics of Mycoplasma hyopneumoniae commercial vaccines and their relationship with field strains, the authors attempted to identify genetic subtypes of some M hyopneumoniae bacterins, and to compare them with M. hyopneumoniae field strains. Six commercial M hyopneumoniae bacterins and 28 bronchoalveolar lavages from pigs at slaughter from three herds were analysed by Multiple-Locus Variable number tandem repeat Analysis (MLVA) on p146R1, p146R3, H4, H5 and p95 loci. The results obtained showed the presence of more than one M hyopneumoniae genotype in some pigs and also in one of the bacterins analysed. It is also worth noting that MLVA typing allowed the distinction among circulating field strains and also when comparing them with vaccine strains, which, knowing the relatedness among them, could be useful in the research of the efficacy of the vaccines. PMID:26495127

  20. Surrogate strains of human pathogens for field release.

    PubMed

    Park, Sangjin; Kim, Chang-Hwan; Jeong, Seong Tae; Lee, Sang Yup

    2017-07-10

    Surrogate microorganisms, in short surrogates, are an essential part of pathogen research. Compared to surrogates used in controlled laboratory environments, surrogates for field release are restricted by concerns about human and environmental safety. For field research of food-borne pathogens, strains of an attenuated pathogen or strains of genetically close non-pathogenic species have been used as surrogates. Genetic modification is usually performed to attenuate virulence, through for examples deletion of genes of virulence and transcriptional regulators and removal of virulence plasmids, and to facilitate detection and monitoring through observing antibiotic resistance, fluorescence, and bioluminescence. For field research of a biological warfare agent Bacillus anthracis, strains of genetically close non-pathogenic species or strains of genetically distant non-pathogenic species have been used, mostly without any genetic modification. Recently, we constructed strains of Bacillus thuringiensis as surrogates for B. anthracis, demonstrating that strain engineering could significantly enhance the utility of surrogates, and that the application of a simple genetic circuit could significantly impact surrogate safety. Thus far, enormous potential of biotechnology has not been exploited enough due to safety concerns regarding the field release of genetically engineered microorganisms. However, synthetic biology is rapidly developing, providing new concepts for biocontainment as well as ingenious genetic circuits and devices, which should be applied in future research of field-use surrogates.

  1. Field practice internship final report

    SciTech Connect

    Foster, T.

    1994-05-01

    This field practice internship final report gives an overview of the field practice, which was completed at the Oak Ridge Y-12 Plant, Martin Marietta Energy Systems, Inc., Environmental Management Department, Oak Ridge, Tennessee. The field practice focused on the completion of the Superfund Amendments and Reauthorization Act (SARA) Title III, Emergency Planning and Community Right-to-Know Act Section 312, Tier II Report. The field practice internship was conducted on a full-time basis between December 13, 1993 through February 18, 1994. Sheila Poligone, Emergency Planning and Community Right-to-Know Act (EPCRA) Coordinator served as the field practice preceptor.

  2. Identification of Strain-Specific Sequences That Distinguish a Mycoplasma gallisepticum Vaccine Strain from Field Isolates

    PubMed Central

    Ricketts, Camir; Pickler, Larissa; Maurer, John; Ayyampalayam, Saravanaraj; García, Maricarmen

    2016-01-01

    ABSTRACT Despite attempts to control avian mycoplasmosis through management, vaccination, and surveillance, Mycoplasma gallisepticum continues to cause significant morbidity, mortality, and economic losses in poultry production. Live attenuated vaccines are commonly used in the poultry industry to control avian mycoplasmosis; unfortunately, some vaccines may revert to virulence and vaccine strains are generally difficult to distinguish from natural field isolates. In order to identify genome differences among vaccine revertants, vaccine strains, and field isolates, whole-genome sequencing of the M. gallisepticum vaccine strain ts-11 and several “ts-11-like” strains isolated from commercial flocks was performed using Illumina and 454 pyrosequencing and the sequenced genomes compared to the M. gallisepticum Rlow reference genome. The collective contigs for each strain were annotated using the fully annotated Mycoplasma reference genome. The analysis revealed genetic differences among vlhA alleles, as well as among genes annotated as coding for a cell wall surface anchor protein (mg0377) and a hypothetical protein gene, mg0359, unique to M. gallisepticum ts-11 vaccine strain. PCR protocols were designed to target 5 sequences unique to the M. gallisepticum ts-11 strain: vlhA3.04a, vlhA3.04b, vlhA3.05, mg0377, and mg0359. All ts-11 isolates were positive for the five gene alleles tested by PCR; however, 5 to 36% of field isolates were also positive for at least one of the alleles tested. A combination of PCR tests for vlhA3.04a, vlhA3.05, and mg0359 was able to distinguish the M. gallisepticum ts-11 vaccine strain from field isolates. This method will further supplement current approaches to quickly distinguish M. gallisepticum vaccine strains from field isolates. PMID:27847370

  3. Area balance and strain in an extensional fault system: Strategies for improved oil recovery in fractured chalk, Gilbertown Field, southwestern Alabama -- Year 2. Annual report, March 1997--March 1998

    SciTech Connect

    Pashin, J.C.; Raymond, D.E.; Rindsberg, A.K.; Alabi, G.G.; Carroll, R.E.

    1998-09-01

    Gilbertown Field is the oldest oil field in Alabama and has produced oil from fractured chalk of the Cretaceous Selma Group and glauconitic sandstone of the Eutaw Formation. Nearly all of Gilbertown Field is still in primary recovery, although waterflooding has been attempted locally. The objective of this project is to analyze the geologic structure and burial history of Mesozoic and Tertiary strata in Gilbertown Field and adjacent areas in order to suggest ways in which oil recovery can be improved. Indeed, the decline of oil production to marginally economic levels in recent years has made this type of analysis timely and practical. Key technical advancements being sought include understanding the relationship of requisite strain to production in Gilbertown reservoirs, incorporation of synsedimentary growth factors into models of area balance, quantification of the relationship between requisite strain and bed curvature, determination of the timing of hydrocarbon generation, and identification of the avenues and mechanisms of fluid transport.

  4. Draft Genome Sequence of Pseudomonas sp. Strain 2-92, a Biological Control Strain Isolated from a Field Plot Under Long-Term Mineral Fertilization.

    PubMed

    Adam, Zaky; Tambong, James Tabi; Chen, Qing; Lewis, Christopher T; Lévesque, C André; Xu, Renlin

    2014-01-09

    Pseudomonas sp. strain 2-92, isolated from a Canadian field plot under long-term mineral fertilization, strongly inhibits the growth of Fusarium graminearum, Rhizoctonia solani, and Gaeumannomyces graminis. Here, we report the draft genome sequence of Pseudomonas sp. strain 2-92.

  5. A seismotectonic model from the strain field of Africa

    NASA Astrophysics Data System (ADS)

    Fernandes, Rui; Meghraoui, Mustapha; Radwan, Ali

    2013-04-01

    Using ~100 available permanent GNSS stations we compute a velocity field to obtain the current strain field in Africa. GPS stations with short data span (>2.5 years data span) and monument/equipment instability are excluded for the estimated velocity field. Although significant gaps of geodetic stations still exist, particularly on the Central and North (include Sahara) Africa, the aim is to produce reliable velocity solutions and evaluate the strain velocity field across the African continent with respect to the latest global reference frame (ITRF2008). We consider in our geodetic data analysis the uncertainties related with the temporal correlations between the daily solutions of stations (computed using HECTOR). The geodynamic characteristics of the African plate and its complex sub-plate distribution are better constrained with the increasing number of GNSS permanent stations in Africa (our latest angular velocity model for the three major tectonic units uses a total of 37 solutions: NUBI: 25; SMLA: 07; VICT: 05). The occurrence of recent large intraplate and interplate earthquakes and volcanic activity in Nubia and Somalia combined with the results of geodetic networks contribute to a better constraint of the kinematics along plate boundaries. The comparison between the geodetic strain rate with the seismic strain release along seismically active plate boundaries permit us to observe the existence of zones of localized active deformation with geodetic rate larger than seismic moment rate. Regional studies also show negligible seismic activity in zones with active faults and where the internal plate deformation estimated with geodetic strain fields is significant. This work is prepared in the framework of the IGCP Project 601 - "Seismotectonics and Seismic Hazards in Africa".

  6. Strain rate orientations near the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Ogasa, N. T.; Kaven, J. O.; Barbour, A. J.; von Huene, R.

    2016-12-01

    Many geothermal reservoirs derive their sustained capacity for heat exchange in large part due to continuous deformation of preexisting faults and fractures that permit permeability to be maintained. Similarly, enhanced geothermal systems rely on the creation of suitable permeability from fracture and faults networks to be viable. Stress measurements from boreholes or earthquake source mechanisms are commonly used to infer the tectonic conditions that drive deformation, but here we show that geodetic data can also be used. Specifically, we quantify variations in the horizontal strain rate tensor in the area surrounding the Coso Geothermal Field (CGF) by analyzing more than two decades of high accuracy differential GPS data from a network of 14 stations from the University of Nevada Reno Geodetic Laboratory. To handle offsets in the data, from equipment changes and coseismic deformation, we segment the data, perform a piecewise linear fit and take the average of each segment's strain rate to determine secular velocities at each station. With respect to North America, all stations tend to travel northwest at velocities ranging from 1 to 10 mm/yr. The nearest station to CGF shows anomalous motion compared to regional stations, which otherwise show a coherent increase in network velocity from the northeast to the southwest. We determine strain rates via linear approximation using GPS velocities in Cartesian reference frame due to the small area of our network. Principal strain rate components derived from this inversion show maximum extensional strain rates of 30 nanostrain/a occur at N87W with compressional strain rates of 37nanostrain/a at N3E. These results generally align with previous stress measurements from borehole breakouts, which indicate the least compressive horizontal principal stress is east-west oriented, and indicative of the basin and range tectonic setting. Our results suggest that the CGF represents an anomaly in the crustal deformation field, which

  7. Demonstration Using Field Collections that Argentina Fall Armyworm Populations Exhibit Strain-specific Host Plant Preferences.

    PubMed

    Murúa, M Gabriela; Nagoshi, Rodney N; Dos Santos, Daniel A; Hay-Roe, Mirian M; Meagher, Robert L; Vilardi, J C

    2015-10-01

    Spodoptera frugiperda, the fall armyworm, is a major economic pest throughout the Western Hemisphere of corn (maize), cotton, sorghum, and a variety of agricultural grasses and vegetable crops. Studies in the United States, the Caribbean, and Brazil demonstrated the existence of two subpopulations (previously designated "host strains") that differ in their choice of plant host. Specifically, the corn strain is preferentially found in corn and sorghum, while the rice strain is dominant in rice, turf grass, and alfalfa. However, inconsistent results were reported in surveys of fall armyworm in Argentina, with some indicating that the host plant preferences of the two strains might be compromised or even nonexistent. If correct, this would complicate efforts to control this pest by considerably expanding the range of habitats that would have to be considered as potential sources for fall armyworm infestations in specific crops. A reexamination of Argentine fall armyworm, this time with field collections rather than the laboratory colonies used in previous studies, confirmed the existence of the two strains and their host preferences. Specifically, the corn strain was consistently the majority population infesting corn and was usually so in sorghum, while the rice strain was predominant in pasture/turf grasses and alfalfa. The one outlier was a collection from rice, which had a corn strain majority. Overall, the data were generally consistent with strain behaviors observed in other areas of the Western Hemisphere.

  8. Characterization of Erwinia amylovora strains from Bulgaria by pulsed-field gel electrophoresis.

    PubMed

    Atanasova, Iliana; Urshev, Zoltan; Hristova, Petya; Bogatzevska, Nevena; Moncheva, Penka

    2012-01-01

    The aim of this study was to characterize genetically Bulgarian Erwinia amylovora strains using pulsed-field gel electrophoresis (PFGE) analysis. Fifty E. amylovora strains isolated from different hosts, locations, as well as in different years were analysed by PFGE after XbaI, SpeI, and XhoI digestion of the genomic DNA. The strains were distributed into four groups according to their XbaI-generated profile. About 82% of the strains displayed a PFGE profile identical to that of type Pt2. Three strains belonged to the Central Europe Pt1 type. Two new PFGE profiles, not reported so far, were established--one for a strain isolated from Malus domestica and another for all Fragaria spp. strains. The same grouping of the strains was obtained after analysis of the SpeI digestion patterns. On the basis of PFGE profiles, after XbaI and SpeI digestion, a genetic differentiation between the strains associated with subfamily Maloideae and subfamily Rosoideae was revealed. The presence of more than one PFGE profile in the population of E. amylovora in Bulgaria suggests a multiple source of inoculum.

  9. Pseudomagnetoexcitons in strained graphene bilayers without external magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Zhigang; Fu, Zhen-Guo; Zheng, Fawei; Zhang, Ping

    2013-03-01

    We propose a strained graphene double-layer (SGDL) system for detecting pseudomagnetoexcitons (PME) in the absence of external magnetic fields. The carriers in each graphene layer experience different strong pseudomagnetic fields (PMFs) due to strain engineering, which give rise to Landau quantization. The pseudo-Landau levels of electron-hole pairs under inhomogeneous PMFs in the SGDL are obtained analytically in the absence of Coulomb interactions. Based on the derived optical absorption selection rule for PMEs, we interpret the optical absorption spectra as indicating the formation of Dirac-type PMEs. We also predict that in the presence of inhomogeneous PMFs, the superfluidity-normal phase-transition temperature of PMEs is greater than that under homogeneous PMFs.

  10. Finite-element study of strain field in strained-Si MOSFET.

    PubMed

    Liu, H H; Duan, X F; Xu, Q X

    2009-02-01

    The strain field in the channel of a p-type metal-oxide-semiconductor field effect transistor fabricated by integrating Ge pre-amorphization implantation for source/drain regions is evaluated using a finite-element method combining with large angle convergent-beam electron diffraction (LACBED). The finite-element calculation shows that there is a very large compressive strain in the top layer of the channel region caused by a low dose of Ge ion implantation in the source and drain extension regions. Moreover, a transition region is formed in the bottom of the channel region and the top of the Si substrate. These calculation results are in good agreement with the LACBED experiments.

  11. Phylogenetic and geographic analysis of fowl adenovirus field strains isolated from poultry in Poland.

    PubMed

    Niczyporuk, Jowita Samanta

    2016-01-01

    Fowl adenoviruses (FAdVs) are widely distributed in chickens in Poland and throughout the world. FAdV infections have been reported in the United States, Australia, Europe, and the Mediterranean basin. Detection of FAdVs strains is very important from the epidemiological point of view and for monitoring disease outbreaks and developing strategies for vaccine development. Several molecular epidemiology and phylogenetic studies have been performed, but the results obtained are still limited, because FAdV strains, even of the same serotype, have very diverse characteristics. Some strains are pathogenic and some are nonpathogenic. This report describes the successful isolation of 96 FAdV field strains from chickens in Poland. A PCR assay specific for the L1 loop region of the hexon gene was conducted, and the products were subjected to sequence analysis. The sequences were analysed using BLAST and Geneious 6.0 software and compared to adenovirus field and reference strain sequences from different parts of the world that are accessible in the NCBI GenBank database. The sequences of the adenovirus strains indicated that they belonged to five species, Fowl aviadenovirus A-E, represented by eight serotypes FAdV-1, FAdV-4, FAdV-5, FAdV-7, FAdV-8a, FAdV-8b, and FAdV-2/11 (FAdV-D). The relationships between FAdVs isolated in Poland and isolates from other regions of the world were determined.

  12. Differences in susceptibility and physiological fitness of Mexican field Trichoplusia ni strains exposed to Bacillus thuringiensis.

    PubMed

    Tamez-Guerra, Patricia; Damas, Gabriela; Iracheta, Maria M; Oppert, Brenda; Gomez-Flores, Ricardo; Rodríguez-Padilla, Cristina

    2006-06-01

    The use of different commercial Bacillus thuringiensis (Bt) products in the Bajio guanajuatense area in Mexico began 12 yr ago, and resistance to Bt in this area has been reported for Plutella xylostella (L.) The current study provides a baseline response and resistance potential to Bt in field and laboratory strains of Bajio Trichoplusia ni (Hübner). Differences in susceptibility to Bt among T. ni populations were observed. T. ni neonates collected in Romita, Guanajuato, were more susceptible to Bt than those collected in Salvatierra or San Luis de la Paz, Guanajuato. After five generations of exposure to XenTari in the laboratory, decreased susceptibility was found only in the Salvatierra insects, with an LC50 that was 2.1-fold greater than that of a Mexican laboratory strain. The XenTari-selected San Luis de la Paz strain was from 16- to 87-fold more resistant to CrylA protoxins than U.S. (US) and Mexican laboratory strains. Although CrylAb is not a component of XenTari, this strain also was significantly less susceptible to CrylAb toxin compared with a US strain, with a resistance ratio of 40.4. The larval weights and lengths, pupal lengths, and percentage of pupation were significantly lower for the Salvatierra strain than for all other strains. The relationship of T. ni susceptibilities to Bt Cry toxins and protoxins after several generations of exposure to XenTari and its similarity to P. xylostella behavior.

  13. Four-wave dark-field electron holography for imaging strain fields

    NASA Astrophysics Data System (ADS)

    Denneulin, T.; Hÿtch, M.

    2016-06-01

    Strain characterization by transmission electron microscopy is an active area of research especially for microelectronics applications. Two-wave dark-field electron holography (DFEH) was previously introduced as a reliable strain mapping technique. Here, DFEH with four electron waves was investigated in order to image equi-displacement lines as amplitude modulations of the holographic fringes. Two perpendicular electrostatic biprisms are used to interfere three reference waves diffracted by a substrate and one object wave diffracted by an epitaxially strained region. This technique provides a different way to represent the displacement field. It might be helpful to obtain information about the strain state during in situ experiments. A dummy p-MOSFET device with embedded SiGe source and drain is used for experimental demonstration.

  14. Developments of scanning probe microscopy with stress/strain fields.

    PubMed

    Guo, H X; Fujita, D

    2011-12-01

    An innovative stress/strain fields scanning probe microscopy in ultra high vacuum (UHV) environments is developed for the first time. This system includes scanning tunneling microscope (STM) and noncontact atomic force microscope (NC-AFM). Two piezo-resistive AFM cantilever probes and STM probes used in this system can move freely in XYZ directions. The nonoptical frequency shift detection of the AFM probe makes the system compact enough to be set in the UHV chambers. The samples can be bent by an anvil driven by a step motor to induce stress and strain on their surface. With a direct current (dc) power source, the sample can be observed at room and high temperatures. A long focus microscope and a monitor are used to observe the samples and the operation of STM and AFM. Silicon(111) surface in room temperature and silicon(001) surface in high temperature with stress were investigated to check the performance of the scanning probe microscope.

  15. Visualizing Strain-Induced Pseudomagnetic Fields in Graphene through an hBN Magnifying Glass

    NASA Astrophysics Data System (ADS)

    Jiang, Yuhang; Mao, Jinhai; Duan, Junxi; Lai, Xinyuan; Watanabe, Kenji; Taniguchi, Takashi; Andrei, Eva Y.

    2017-05-01

    The remarkable properties of graphene are inherent to its 2D honeycomb lattice structure. Its low dimensionality, which makes it possible to rearrange the atoms by applying an external force, offers the intriguing prospect of mechanically controlling the electronic properties. In the presence of strain, graphene develops a pseudo-magnetic field (PMF) which reconstructs the band structure into pseudo Landau levels (PLLs). However, a feasible route to realizing, characterizing and controlling PMFs is still lacking. Here we report on a method to generate and characterize PMFs in a graphene membrane supported on nano-pillars. A direct measure of the local strain is achieved by using the magnifying effect of the Moir\\'e pattern formed against a hexagonal Boron Nitride (hBN) substrate under scanning tunneling microscopy (STM). We quantify the strain induced PMF through the PLLs spectra observed in scanning tunneling spectroscopy (STS). This work provides a pathway to strain induced engineering and electro-mechanical graphene based devices.

  16. Report of near field group

    SciTech Connect

    Palmer, R.B.; Baggett, N.; Claus, J.; Fernow, R.; Stumer, I.; Figueroa, H.; Kroll, N.; Funk, W.; Lee-Whiting, G.; Pickup, M.

    1985-04-01

    Substantial progress since the Los Alamos Workshop two years ago is reported. A radio-frequency model of a grating accelerator has been tested at Cornell, and extensive calculations compared with observations. Alternative structures consisting of either hemispherical bumps on a plane, or conducting spheres in space, have also been rf modeled. The use of liquid droplets to form such structures has been proposed and a conceptual design studied. Calculations and experiments have examined the effects of surface plasmas, and shown that in this case the reflectivity is low. However, calculations and observations suggest that gradients in excess of 1 GeV/meter should be obtainable without forming such plasma. An examination of wake fields shows that, with Landau damping, these are independent of wavelength. The use of near field structures to act as high gradient focusing elements has been studied and shows promise, independent of the acceleration mechanism. A proposal has been made to establish a facility that would enable ''proof of principle experiments'' to be performed on these and other laser driven accelerator mechanisms. 11 refs., 10 figs.

  17. Molecular typing of Leptospira spp. strains isolated from field mice confirms a link to human leptospirosis.

    PubMed

    Li, S J; Wang, D M; Zhang, C C; Li, X W; Yang, H M; Tian, K C; Wei, X Y; Liu, Y; Tang, G P; Jiang, X G; Yan, J

    2013-11-01

    In recent years, human leptospirosis has been reported in Jinping and Liping counties, Guizhou province, but the leptospires have never been isolated. To track the source of infection and understand the aetiological characteristics, we performed surveillance for field mice carriage of leptospirosis in 2011. Four strains of leptospire were isolated from Apodemus agrarius. PCR confirmed the four isolates as pathogenic. Multiple-locus variable-number tandem repeat analysis (MLVA) showed that the four strains were closely related to serovar Lai strain 56601 belonging to serogroup Icterohaemorrhagiae, which is consistent with the antibody detection results from local patients. Furthermore, the diversity of leptospiral isolates from different hosts and regions was demonstrated with MLVA. Our results suggest that A. agrarius may be the main carrier of Leptospira in Jinping and Liping counties, and the serogroup Icterohaemorrhagiae serovar may be the epidemic serogroup of Leptospira. This will contribute to the control and prevention of leptospirosis in these localities.

  18. Comparison of Haemophilus parasuis reference strains and field isolates by using random amplified polymorphic DNA and protein profiles

    PubMed Central

    2012-01-01

    Background Haemophilus parasuis is the causative agent of Glässer’s disease and is a pathogen of swine in high-health status herds. Reports on serotyping of field strains from outbreaks describe that approximately 30% of them are nontypeable and therefore cannot be traced. Molecular typing methods have been used as alternatives to serotyping. This study was done to compare random amplified polymorphic DNA (RAPD) profiles and whole cell protein (WCP) lysate profiles as methods for distinguishing H. parasuis reference strains and field isolates. Results The DNA and WCP lysate profiles of 15 reference strains and 31 field isolates of H. parasuis were analyzed using the Dice and neighbor joining algorithms. The results revealed unique and reproducible DNA and protein profiles among the reference strains and field isolates studied. Simpson’s index of diversity showed significant discrimination between isolates when three 10mer primers were combined for the RAPD method and also when both the RAPD and WCP lysate typing methods were combined. Conclusions The RAPD profiles seen among the reference strains and field isolates did not appear to change over time which may reflect a lack of DNA mutations in the genes of the samples. The recent field isolates had different WCP lysate profiles than the reference strains, possibly because the number of passages of the type strains may affect their protein expression. PMID:22703293

  19. Near tip stress and strain fields for short elastic cracks

    NASA Technical Reports Server (NTRS)

    Soediono, A. H.; Kardomateas, G. A.; Carlson, R. L.

    1994-01-01

    Recent experimental fatigue crack growth studies have concluded an apparent anomalous behavior of short cracks. To investigate the reasons for this unexpected behavior, the present paper focuses on identifying the crack length circumstances under which the requirements for a single parameter (K(sub I) or delta K(sub I) if cyclic loading is considered) characterization are violated. Furthermore, an additional quantity, the T stress, as introduced by Rice, and the related biaxiality ratio, B, are calculated for several crack lengths and two configurations, the single-edge-cracked and the centrally-cracked specimen. It is postulated that a two-parameter characterization by K and T (or B) is needed for the adequate description of the stress and strain field around a short crack. To further verify the validity of this postulate, the influence of the third term of the Williams series on the stress, strain and displacement fields around the crack tip and in particular on the B parameter is also examined. It is found that the biaxiality ratio would be more negative if the third term effects are included in both geometries. The study is conducted using the finite element method with linearly elastic material and isoparametric elements and axial (mode I) loading. Moreover, it is clearly shown that it is not proper to postulate the crack size limits for 'short crack' behavior as a normalized ratio with the specimen width, a/w; it should instead be stated as an absolute, or normalized with respect to a small characteristic dimension such as the grain size. Finally, implications regarding the prediction of cyclic (fatigue) growth of short cracks are discussed.

  20. Progress Report on Alloy 617 Isochronous Stress-Strain Curves

    SciTech Connect

    Jill K. Wright; Richard N. Wright; Nancy J. Lybeck

    2014-03-01

    Isochronous stress-strain curves for Alloy 617 up to a temperature of 1000°C will be required to qualify the material for elevated temperature design in Section III, Division 1, Subsection NH of the ASME Boiler and Pressure Vessel Code. Several potential methods for developing these curves are reviewed in this report. It is shown that in general power-law creep is the rate controlling deformation mechanism for a wide range of alloy heats, test temperatures and stresses. Measurement of the strain rate sensitivity of Alloy 617 indicates that the material is highly strain rate sensitive in the tensile deformation range above about 750°C. This suggests that the concept of a hot tensile curve as a bounding case on the isochronous stress-strain diagrams is problematic. The impact of strain rate on the hot tensile curves is examined and it is concluded that incorporating such a curve is only meaningful if a single tensile strain rate (typically the ASTM standard rate of 0.5%/min) is arbitrarily defined. Current experimentally determined creep data are compared to isochronous stress-strain curves proposed previously by the German programs in the 1980s and by the 1990 draft ASME Code Case. Variability in how well the experimental data are represented by the proposed design curves that suggests further analysis is necessary prior to completing a new draft Code Case.

  1. Wide-field strain imaging with preferentially aligned nitrogen-vacancy centers in polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Trusheim, Matthew E.; Englund, Dirk

    2016-12-01

    We report on wide-field optically detected magnetic resonance imaging of nitrogen-vacancy centers (NVs) in type IIa polycrystalline diamond. These studies reveal a heterogeneous crystalline environment that produces a varied density of NV centers, including preferential orientation within some individual crystal grains, but preserves long spin coherence times. Using the native NVs as nanoscale sensors, we introduce a three-dimensional strain imaging technique with high sensitivity (< {10}-5 Hz-1/2) and diffraction-limited resolution across a wide field of view.

  2. Frequency dependent optical conductivity of strained graphene at T=0 from an effective quantum field theory

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Jiang; Pan, Hui; Wang, Hai-Long

    2017-04-01

    An effective quantum field theory (EQFT) graphene sheet with arbitrary one dimensional strain field is derived from a microscopic effective low energy Hamiltonian. The geometric meaning of the strain-induced complex gauge field is clarified. The optical conductivity is also investigated, and a frequency dependent optical conductivity is obtained. The actual value of interband optical conductivity along the deformed direction is C0 + C1/ω2 in spite of the particular strain fields at T=0.

  3. Hydrogen Concentration and Strain Fields Near Fatigue Cracks in Pipeline Steel Measured Via Neutron Imaging

    NASA Astrophysics Data System (ADS)

    Connolly, Matthew; Slifka, Andrew; Drexler, Elizabeth; Hydrogen Pipeline Safety Team

    Hydrogen (H2) is desirable for energy storage as it is cleaner burning and can store a larger amount of energy than an equal mass of gasoline. One problem in the development of a hydrogen economy is to find or develop materials that ensure the safe, reliable, and cost-effective flow of energy from the source to the user. It is expected steels will be needed to serve this function. However, the existing network of natural gas pipeline, for example, is constructed of ferrous materials which are susceptible to embrittlement and subsequent increased fatigue crack growth rates after exposure to hydrogen. In order to improve current modeling efforts, experimental determination of hydrogen concentration, hydrogen diffusion rates, and strain fields are required to inform and validate the model. Here we report neutron imaging measurements of the hydrogen concentration near a fatigue crack and the corresponding strain field, measured via neutron transmission Bragg edge spectroscopy. Nist Materials Measurement Laboratory, Applied Chemicals and Materials Division.

  4. Viral diversity of Junín virus field strains.

    PubMed

    Goñi, Sandra E; Stephan, Betina I; Iserte, Javier A; Contigiani, Marta S; Lozano, Mario E; Tenorio, Antonio

    2011-09-01

    The Argentine Hemorrhagic Fever, an endemic disease present in a much of Argentina, is caused by the Junín virus (JUNV). Currently, there are sequences available from several strains of this virus, like those belonging to the vaccine lineage (XJ13, XJ#44 and Candid#1), as well as MC2 (rodent isolate) and IV4454 (human isolate). In this article, we report sequence information on two fragments of genomic segment S of viral isolates from the endemic area. A Nested-RT-PCR was used to amplify discrete genomic regions of 13 isolates of rodent and human origin. The bioinformatics studies revealed a great homogeneity of sequences among the JUNV isolates. The phylogenetic classification showed greater evolutionary distance between the old world arenaviruses (Lassa and LCM virus) than between the new world arenaviruses (JUNV and Machupo virus).

  5. Extent of validity of three-parameter crack-tip strain fields

    NASA Astrophysics Data System (ADS)

    Berger, J. R.; Dally, J. W.; Sanford, R. J.

    Error maps showing the differences in strains determined from three-term series representation of the strain field are developed for several different crack lengths in a SEN fracture specimen. To assess the validity of the three-parameter strain field model, a series of FEM analyses was conducted to determine the series coefficients in a large-order expansion of the strain field. Through knowledge of the higher-order (nonsingular) terms, the error was examined over a reasonably sized area between strain calculated from a three-parameter model and a strain calculated using a large-order model. This error is studied by choosing a point in the field, calculating the strain at this point using both three- and large-parameter models, and comparing the two strain values. The gage inclusion/exclusion criteria are determined by performing this analysis for a variety of crack lengths.

  6. Sex linkage of CpGV resistance in a heterogeneous field strain of the codling moth Cydia pomonella (L.).

    PubMed

    Asser-Kaiser, Sabine; Heckel, David G; Jehle, Johannes A

    2010-01-01

    The occurrence of codling moth populations in European apple orchards that were not controlled by Cydia pomonella granulovirus (CpGV) is the first reported case of field resistance against a baculovirus control agent. A monogenic dominant sex-linked mode of inheritance was previously demonstrated in single-pair crosses between a homogeneous resistant (CpRR1) and a susceptible (CpS) laboratory strain of codling moth. However, resistant field populations (CpR) are more heterogeneous in their levels of resistance, and the possibility that they could harbor different resistance genes to CpRR1 had not been directly addressed. Here we report single pair crossing experiments using a resistant codling moth strain collected from an apple orchard in the southwest of Germany. Single-pair crosses within the field strain revealed a genetic basis to the heterogeneity of CpR concerning CpGV resistance. Hybrid crosses to a susceptible laboratory strain and backcrosses of the F1 generation to the resistant CpR strain confirmed that the homogeneous CpRR1 and the heterogeneous field strain CpR share the same mode of inheritance. Thus the variable levels of CpGV resistance in field populations is likely due to frequency differences of the same resistance-conferring gene, rather than different genes, which will facilitate future efforts to monitor and manage resistance.

  7. Field Organizations: Unit Status Reporting

    DTIC Science & Technology

    2001-11-15

    percentage a. Personnel turnover percentage ( APERT ) provides an indicator of unit turmoil (degradation of unit capability). Compute personnel...calculated in step 9. Enter “0” for APS. (5) APERT (field 6, personnel turnover percentage). (a) GAINS (field 6, # gains). Enter the number of gains from...6, # losses). Enter the number of losses from the last 90 days. (c) APERT (field 6, T/O percentage). Use percentage calculated in paragraph 4–8. (6

  8. GPS Velocity and Strain Rate Fields in Southwest Anatolia from Repeated GPS Measurements

    PubMed Central

    Erdoğan, Saffet; Şahin, Muhammed; Tiryakioğlu, İbrahim; Gülal, Engin; Telli, Ali Kazım

    2009-01-01

    Southwestern Turkey is a tectonically active area. To determine kinematics and strain distribution in this region, a GPS network of sixteen stations was established. We have used GPS velocity field data for southwest Anatolia from continuous measurements covering the period 2003 to 2006 to estimate current crustal deformation of this tectonically active region. GPS data were processed using GAMIT/GLOBK software and velocity and strain rate fields were estimated in the study area. The measurements showed velocities of 15–30 mm/yr toward the southwest and strain values up to 0.28–8.23×10−8. Results showed that extension has been determined in the Burdur-Isparta region. In this study, all of strain data reveal an extensional neotectonic regime through the northeast edge of the Isparta Angle despite the previously reported compressional neotectonic regime. Meanwhile, results showed some small differences relatively with the 2006 model of Reilinger et al. As a result, active tectonic movements, in agreement with earthquake fault plane solutions showed important activity. PMID:22573998

  9. Susceptibility of laboratory and field strains of four stored-product insect species to spinosad.

    PubMed

    Huang, Fangneng; Subramanyam, Bhadriraju; Toews, Michael D

    2004-12-01

    Two field strains of the Indianmeal moth, Plodia interpunctella (Hübner); red flour beetle, Tribolium castaneum (Herbst); and lesser grain borer, Rhyzopertha dominica (F.), and one field strain of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were collected from hard red winter wheat stored on farms in northeastern Kansas. Fifty eggs of P. interpunctella and 25 beetle adults of each species were exposed to 100 g of untreated wheat or wheat treated with various rates of spinosad, to determine susceptibility of the field and corresponding insecticide-susceptible laboratory strains. Mortality of beetle adults and P. interpunctella larvae was assessed after 7 and 21 d postinfestation, respectively. Field strains of P. interpunctella, C. ferrugineus, and T. castaneum were less susceptible to spinosad than the corresponding laboratory strains. The LD50 and LD95 values for P. interpunctella and C. ferrugineus field strains were 1.7-2.5 times greater than values for corresponding laboratory strains. Adults of both laboratory and field strains of T. castaneum were tolerant to spinosad, resulting in <88% mortality at 8 mg/kg. The LD50 and LD95 values for the field strains of T. castaneum were 2.0-7.5 times greater compared with similar values for the laboratory strain. The field and laboratory strains of R. dominica were highly susceptible to spinosad, and one of the field strains was relatively less susceptible to spinosad than the laboratory strain. Our results confirm a range of biological variability in field populations, which is consistent with findings for other compounds, and underscores the need to adopt resistance management programs with stored grain insect pests. The baseline data generated on the susceptibility of the four insect species to spinosad will be useful for monitoring resistance development and for setting field rates.

  10. Strain fields and electronic structure of CrN

    NASA Astrophysics Data System (ADS)

    Rojas, Tomas; Ulloa, Sergio E.

    Chromium nitride (CrN) has a promising future for its resistance to corrosion and hardness, and very interesting magnetic and electronic properties. CrN presents a phase transition in which the crystal structure, magnetic ordering and electronic properties change at a (Néel) temperature ~ 280 K . Thin films from different labs exhibit different conductance behavior at low temperature. We study the unusual electronic and magnetic properties of thin layers. For that purpose we develop a tight binding Hamiltonian based on the Slater-Koster approach, and estimate the interaction between the Cr-3d and N-2p orbitals, by analyzing the band structure and comparing it with ab initio calculations performed using the LSDA+U method. These calculations show the system to behave as a semiconductor below the Néel temperature. Based on our model we calculate the effective masses and analyze the effect of strain fields in the electronic structure in order to understand the electronic behavior near the phase transition. Supported by NSF DMR-1508325.

  11. Electric field induced strain, switching and energy storage behaviour of lead free Barium Zirconium Titanate ceramic

    NASA Astrophysics Data System (ADS)

    Badapanda, T.; Chaterjee, S.; Mishra, Anupam; Ranjan, Rajeev; Anwar, S.

    2017-09-01

    There is a huge demand of lead-free high performance ceramics with large strain, low hysteresis loss and high-energy storage ability at room temperature. In this context, we investigated the large electric field induced strain, switching behaviour and energy storage properties of BaZr0.05Ti0.95O3 ceramic (BZT) prepared by high energy ball milling technique, reportedly exhibiting a triple point transition near the room temperature. The X-ray diffraction of the BZT ceramic confirms orthorhombic symmetry with space group Amm2 at room temperature. The room temperature dielectric study reveals that there is a negligible variation of dielectric constant and dielectric loss with frequency. The polarization behaviour at various applied electric fields was studied and the energy storage densities were obtained from the integral area of P-E loops. Electric field induced strain behaviour has been studied with due emphasis on the electrostrictive response at room temperature. The ferroelectric and electromechanical properties derived from the P-E and S-E loops suggest that the present ceramic encompass the properties of actuation and energy storage simultaneously.

  12. Field sampling and travel report

    USDA-ARS?s Scientific Manuscript database

    Dr. Sigua was involved with two field visits of watersheds with different livestock production systems (poultry, swine, and beef/dairy cattle); one in the sub-basins of Pinhal River Watershed (October 23, 2008) and at the micro-basins of the Rio Pine Forest (October 29, 2008) where studies of assess...

  13. Surface mapping of field-induced piezoelectric strain at elevated temperature employing full-field interferometry.

    PubMed

    Stevenson, Tim; Quast, Tatjana; Bartl, Guido; Schmitz-Kempen, Thorsten; Weaver, Paul M

    2015-01-01

    Piezoelectric actuators and sensors are widely used for flow control valves, including diesel injectors, ultrasound generation, optical positioning, printing, pumps, and locks. Degradation and failure of material and electrical properties at high temperature typically limits these applications to operating temperatures below 200°C, based on the ubiquitous Pb(Zr,Ti)O3 ceramic. There are, however, many applications in sectors such as automotive, aerospace, energy and process control, and oil and gas, where the ability to operate at higher temperatures would open up new markets for piezoelectric actuation. Presented here is a review of recent progress and initial results toward a European effort to develop measurement techniques to characterize high-temperature materials. Full-field, multi-wavelength absolute length interferometry has, for the first time, been used to map the electric-field-induced piezoelectric strain across the surface of a PZT ceramic. The recorded variation as a function of temperature has been evaluated against a newly developed commercial single-beam system. Conventional interferometry allows measurement of the converse piezoelectric effect with high precision and resolution, but is often limited to a single point, average measurement and to limited sample environments because of optical aberrations in varying atmospheres. Here, the full-field technique allows the entire surface to be analyzed for strain and, in a bespoke sample chamber, for elevated temperatures.

  14. Mechanisms underlying fipronil resistance in a multiresistant field strain of the German cockroach (Blattodea: Blattellidae).

    PubMed

    Gondhalekar, Ameya D; Scharf, Michael E

    2012-01-01

    German cockroaches (Blattella germanica L.) have significant impacts on human health, most notably they are implicated as causes of childhood asthma. Gel bait formulations of fipronil, a phenylpyrazole insecticide, have been in use for German cockroach control in the United States since 1998. Previously, dieldrin resistant German cockroach strains were shown to have 7- to 17-fold cross-resistance to fipronil. More recently, a field-collected strain (GNV-R) displayed approximately 36-fold resistance to topically applied fipronil at the LD50 level, which is the highest level of fipronil resistance reported to date in the German cockroach. The aim of the current research was to identify mechanism(s) responsible for high-level fipronil resistance in the GNV-R strain. Synergist bioassays conducted using topical and injection application methods implicated cytochrome P450-mediated detoxification in resistance. Electrophysiological recordings using the suction-electrode technique revealed the nervous system of the GNV-R strain is insensitive to fipronil. In agreement with electrophysiology results, the alanine to serine (A302S) mutation encoded by the gamma-amino butyric acid-gated chloride channel subunit gene resistance to dieldrin, which confers limited cross-resistance to fipronil, was detected in 95% of GNV-R strain individuals. Logistic regression analysis showed that A302S mutation frequency correlates with neurological insensitivity as shown by electrophysiology data. Overall, results of synergism bioassays, electrophysiological recordings, and A302S mutation frequency measurements suggest that fipronil resistance in the GNV-R strain is caused by the combined effects of enhanced metabolism by cytochrome P450s and target-site insensitivity caused by the A302S-encoding mutation in the resistance to dieldrin gene.

  15. Ability of vaccine strain induced antibodies to neutralize field isolates of caliciviruses from Swedish cats.

    PubMed

    Wensman, Jonas Johansson; Samman, Ayman; Lindhe, Anna; Thibault, Jean-Christophe; Berndtsson, Louise Treiberg; Hosie, Margaret J

    2015-12-12

    Feline calicivirus (FCV) is a common cause of upper respiratory tract disease in cats worldwide. Its characteristically high mutation rate leads to escape from the humoral immune response induced by natural infection and/or vaccination and consequently vaccines are not always effective against field isolates. Thus, there is a need to continuously investigate the ability of FCV vaccine strain-induced antibodies to neutralize field isolates. Seventy-eight field isolates of FCV isolated during the years 2008-2012 from Swedish cats displaying clinical signs of upper respiratory tract disease were examined in this study. The field isolates were tested for cross-neutralization using a panel of eight anti-sera raised in four pairs of cats following infection with four vaccine strains (F9, 255, G1 and 431). The anti-sera raised against F9 and 255 neutralised 20.5 and 11.5 %, and 47.4 and 64.1 % of field isolates tested, respectively. The anti-sera against the more recently introduced vaccine strains G1 and 431 neutralized 33.3 and 55.1 % (strain G1) or 69.2 and 89.7 % (strain 431) of the field isolates with titres ≥5. [corrected]. Dual vaccine strains displayed a higher cross-neutralization. This study confirms previous observations that more recently introduced vaccine strains induce antibodies with a higher neutralizing capacity compared to vaccine strains that have been used extensively over a long period of time. This study also suggests that dual FCV vaccine strains might neutralize more field isolates compared to single vaccine strains. Vaccine strains should ideally be selected based on updated knowledge on the antigenic properties of field isolates in the local setting, and there is thus a need for continuously studying the evolution of FCV together with the neutralizing capacity of vaccine strain induced antibodies against field isolates at a national and/or regional level.

  16. Comparative histopathological and immunological study of two field strains of chicken anemia virus.

    PubMed

    Rimondi, Agustina; Pinto, Silvina; Olivera, Valeria; Dibárbora, Marina; Pérez-Filgueira, Mariano; Craig, María Isabel; Pereda, Ariel

    2014-10-08

    Infection of poultry with chicken anemia virus (CAV) is implicated in several field problems in broiler flocks due to the immunosuppression generated and, consequently, the increased susceptibility to secondary infections. Recently, we have reported an increased occurrence of clinical cases caused by CAV strains distantly related to those commonly used for vaccination. In order to understand the behavior of two Argentinean CAV strains (CAV-10 and CAV-18) in two-week-old chickens, an immune and histopathological study was performed. Neither mortality nor clinical signs were observed in the infected or control groups. Thymus lobes from chickens infected with both CAV viruses were smaller compared to the negative control group. At 14 days post-infection (dpi), only chickens inoculated with CAV-10 show a severe depletion of lymphocytes in the thymus cortex and in follicles from the bursa of Fabricius. Also thymopoiesis disorders, such as reduction in the percentage of total DP (CD4 + CD8α+) thymocytes and alteration in the percentages of DP subpopulations, were more important in animals inoculated with the CAV-10 than the CAV-18 strain. In addition, only animals infected with CAV-10 show a decrease in CD8αβ splenocytes. Altogether our results show that, although both Argentinean CAV strains produce subclinical infections in chickens causing immunosuppression at 14 dpi, they might differ in their in vivo pathogenicity.

  17. Molecular relationship between field and vaccine strain of measles virus and its persistence in Pakistan

    PubMed Central

    2012-01-01

    Background Countrywide 5.9 million, 0-11 Month old children are immunized annually by EPI (Expended Program on Immunization) against 8 vaccine preventable diseases including measles and so on. Unfortunately the basic immunity centers are not uniform throughout the country. Each center provides services to about 27000 people which is inadequate. The purpose of this study was to explore the development of EPI Pakistan in terms of immunization of measles. Methods Nucleotide sequences were analyzed by neighbor joining method (bootstrap test) using Bio- edit and MEGA-5 software to find evolutionary relationship between wild type measles strain and vaccine strain (Edmonston strain) used in Pakistan. For statistical analysis of data SPSS 16 was used. Results Currently 1.3 vaccinators are working at each U C (union council) which according to national EPI policy should be at least 2. About 56% and 44% children of age 0-11 months did not received second dose of measles in the last two years respectively. Out of these 4231 cases which were reported last year, 1370 have received their first dose of measles vaccine. Conclusion Seroconversion and seroprevalence study of the vaccine and field strain of measles virus is needed to confirm whether its failure is due to service unavailability or vaccine in-affectivity. PMID:22284834

  18. Local magnetic fields, uplift, gravity, and dilational strain changes in Southern California ( USA).

    USGS Publications Warehouse

    Johnston, M.J.S.

    1986-01-01

    Measurements of regional magnetic field near the San Andreas fault at Cajon, Palmdale and Tejon are strongly correlated with changes in gravity, areal strain, and uplift in these regions during the period 1977-1984. Because the inferred relationships between these parameters are in approximate agreement with those obtained from simple deformation models, the preferred explanation appeals to short-term strain episodes independently detected in each data set. Transfer functions from magnetic to strain, gravity, and uplift perturbations, obtained by least-square linear fits to the data, are -0.98 nT/ppm, -0.03 nT/mu Gal, and 9.1 nT/m respectively. Tectonomagnetic model calculations underestimate the observed changes and those reported previously for dam loading and volcano-magnetic observations. A less likely alternative explanation of the observed data appeals to a common source of meteorologically generated crustal or instrumental noise in the strain, gravity, magnetic, and uplift data.-from Author

  19. Strain fields and electronic structure of antiferromagnetic CrN

    NASA Astrophysics Data System (ADS)

    Rojas, Tomas; Ulloa, Sergio E.

    2017-09-01

    We present a theoretical analysis of the role that strain plays on the electronic structure of chromium nitride (CrN) crystals. We use local spin-density approximation + U calculations to study the elastic constants, deformation potentials, and strain dependence of electron and hole masses near the fundamental gap. We consider the lowest energy antiferromagnetic models believed to describe CrN at low temperatures, and apply strain along different directions. We find relatively large deformation potentials for all models, and find increasing gaps for tensile strain along most directions. Most interestingly, we find that compressive strains should be able to close the relatively small indirect gap (≃100 meV) at moderate amplitudes ≃1.3 % . We also find large and anisotropic changes in the effective masses with strain, with principal axes closely related to the magnetic ordering of neighboring layers in the antiferromagnet. It would be interesting to consider the role that these effects may have on typical film growth on different substrates, and the possibility of monitoring optical and transport properties of thin films as strain is applied.

  20. Insecticide Resistance of Several Field-Collected German Cockroach (Dictyoptera: Blattellidae) Strains.

    PubMed

    Wu, Xiaoyan; Appel, Arthur G

    2017-03-08

    German cockroaches, Blattella germanica (L.), remain one of the most difficult indoor insect species to control because of its ability to develop resistance to insecticides. The toxicity and resistance levels of five technical-grade insecticides (permethrin, chlorpyrifos, propoxur, imidacloprid, and fipronil) were determined for adult males of seven strains of the German cockroach, a laboratory-reared susceptible strain (S) and six field-collected strains (B, D, E, G, H, and I). Using topical application methods, fipronil was the most toxic insecticide to all seven strains. The LD50 values of fipronil in the susceptible strain (S) and the field-collected strains B, D, E, G, H, and I were 1.33, 2.62, 11.53, 5.07, 7.66, 5.15, and 10.15 ng/insect, respectively. The field-collected strains were most resistant to permethrin among the five insecticides, except for strain H. The resistance ratios of strains B, D, E, G, and I to permethrin were 31.8, 37.3, 51.9, 34.9, and 37.5, respectively. With a resistance ratio of 6.4, the field-collected strain H was most resistant to chlorpyrifos. The field-collected strains were not significantly resistant to propoxur. Strains B, H, and I were not significantly resistant to imidacloprid when compared with the susceptible strain. Based on the different resistance ratios for each insecticide, we conclude that there are high rates of insecticide resistance in German cockroaches from Franklin County, NC, and that the field-collected strains most likely had different treatment histories.

  1. [Application of reporter strains for new antibiotic screening].

    PubMed

    Sergiev, P V; Osterman, I A; Golovina, A Ya; Laptev, I G; Pletnev, P I; Evfratov, S A; Marusich, E I; Leonov, S V; Ivanenkov, Ya A; Bogdanov, A A; Dontsova, O A

    2016-01-01

    Screening for new antibiotics remains an important area of biology and medical science. Indispensable for this type of research is early identification of antibiotic mechanism of action. Preferentially, it should be studied quickly and cost-effectively, on the stage of primary screening. In this review we describe an application of reporter strains for rapid classification of antibiotics by its target, without prior purification of an active compound and determination of chemical structure.

  2. Direct measurement of strain field evolution during dynamic deformation of an energetic material

    SciTech Connect

    Asay, B.W.; Henson, B.F.; Dickson, P.M.; Fugard, C.S.; Funk, D.J.

    1997-09-01

    The authors previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. They have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  3. Direct measurement of strain field evolution during dynamic deformation of an energetic material

    NASA Astrophysics Data System (ADS)

    Asay, B. W.; Henson, B. F.; Dickson, P. M.; Fugard, C. S.; Funk, D. J.

    1998-07-01

    We previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. We have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  4. Direct Measurement of Strain Field Evolution During Dynamic Deformation of an Energetic Material

    NASA Astrophysics Data System (ADS)

    Asay, B. W.; Henson, B. F.; Funk, D. J.

    1997-07-01

    We previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. We have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  5. Analysis of strains of Campylobacter fetus by pulsed-field gel electrophoresis.

    PubMed Central

    Fujita, M; Fujimoto, S; Morooka, T; Amako, K

    1995-01-01

    Campylobacter fetus chromosomal DNA from 21 strains was analyzed by pulsed-field gel electrophoresis. The fingerprint patterns generated with SmaI and SalI were distinctive. Using the profiles obtained by pulsed-field gel electrophoresis, we established the phylogenetic dendrogram of C. fetus to identify the genetic relationship of the strains. PMID:7650215

  6. Comparison of Haemophilus parasuis reference strains and field isolates by using random amplified polymorphic DNA and protein profiles

    USDA-ARS?s Scientific Manuscript database

    Haemophilus parasuis is the causative agent of Glässer’s disease and is a pathogen of swine in high-health status herds. Reports on serotyping of field strains from outbreaks describe that approximately 30% of them are nontypable and therefore cannot be traced. Molecular typing methods have been use...

  7. Joint Service Lightweight Integrated Suit Technology Program: Heat Strain Evaluation in an Environmental Chamber and in the Field.

    DTIC Science & Technology

    1998-03-01

    Service Lightweight Integrated Suit Technology Program: Heat Strain Evaluation in an Environmental Chamber and in the Field 6. AUTHOR(S) Leslie...public release; distribution is unlimited. 12b. DISTRIBUTION CODE 13. ABSTRACT (Maximum 200 words) The Joint Service Lightweight Integrated Suit...6218. Approved for public release; distribution is unlimited. TECHNICAL REPORT No. TR Joint Service Lightweight Integrated Suit Technology Program

  8. Complete Genome Sequence of a Potential Novel Bacillus sp. Strain, FJAT-18017, Isolated from a Potato Field

    PubMed Central

    Liu, Guo-Hong; Wang, Jie-Ping; Che, Jian-Mei; Chen, Qian-Qian

    2017-01-01

    ABSTRACT Bacillus sp. strain FJAT-18017 was isolated from a potato field in Xinjiang, China. This paper is the first report, to our knowledge, to demonstrate the fully sequenced and completely annotated genome of Bacillus sp. FJAT-18017. The genome size is 5,265,521 bp. The average G+C content was 42.42%. PMID:28104649

  9. Magnetic field gradiometer. Final technical report

    SciTech Connect

    Fraser-Smith, A.C.

    1983-02-01

    This report has two principal goals. First, to present a general review of magnetic field gradiometers and, second, to provide new data concerning these gradiometers, including new information about their response to magnetic dipole fields. A system of nomenclature is introduced that is consistent with the mathematical concept of gradient and which provides a basis for discussions of the different functions of magnetic field gradiometers and differential magnetometers. The distinction between component gradiometers and total field gradiometers is also stressed.

  10. Derivation of Relations and Analysis of Tube Bending Processes Using Discontinuous Fields of Plastic Strains

    NASA Astrophysics Data System (ADS)

    Śloderbach, Z.

    2015-05-01

    The generalized strain scheme in bending metal tubes at bending machines with the use of a mandrel presented in Śloderbach (1999; 2002; 20131,2; 2014) satisfies initial and boundary kinematic conditions of bending, conditions of continuity and inseparability of strains. This paper introduces three formal simplifications gradually imposed into forms of principal components of the generalized strain model giving suitable simplifications of the 1st, 2nd and 3rd types. Such mathematical simplifications cause that the obtained strain fields do not satisfy the condition of consistency of displacements and strain continuity. The simplified methods determine safer values of the wall thickness than those from the generalized continuous strain scheme. The condition of plastic incompressibility was used for the derivation of an expression for distribution of wall thickness of the bent elbow in the layers subjected to tension and compression for three examples of discontinuous kinematic strain fields.

  11. Measurement of inhomogeneous strain fields by fiber optic sensors embedded in a polymer composite material

    NASA Astrophysics Data System (ADS)

    Anoshkin, A. N.; Voronkov, A. A.; Kosheleva, N. A.; Matveenko, V. P.; Serovaev, G. S.; Spaskova, E. M.; Shardakov, I. N.; Shipunov, G. S.

    2016-09-01

    Experimental results of strain field measurement in polymer composite specimens by Bragg grating fiber optic strain sensors embedded in the material are considered. A rectangular plate and a rectangular plate with "butterfly" shaped cuts are used as specimens. The results of uniaxial strain experiments with rectangular plates show that fiber optic strain sensors can be used to measure the strains, and these results can be used to calculate the calibration coefficients for fiber optic strain sensors. A gradient strain field is attained in a plate with cuts, and the possibility of measuring this field by fiber optic strain sensors is the main goal of this paper. The results of measurements of gradient strain fields in the plate with cuts are compared with the results obtained by using the three-dimensional digital optic system Vix-3D and with the results of numerical computations based on finite element methods. It is shown that the difference between the strain values obtained by these three methods does not exceed 5%.

  12. The Anti-Phytophthora Effect of Selected Potato-Associated Pseudomonas Strains: From the Laboratory to the Field

    PubMed Central

    Guyer, Anouk; De Vrieze, Mout; Bönisch, Denise; Gloor, Ramona; Musa, Tomke; Bodenhausen, Natacha; Bailly, Aurélien; Weisskopf, Laure

    2015-01-01

    Late blight, caused by the oomycete Phytophthora infestans, is the most devastating disease of potato. In organic farming, late blight is controlled by repeated applications of copper-based products, which negatively impact the environment. To find alternative solutions for late blight management, we have previously isolated a large collection of bacteria from the phyllosphere and the rhizosphere of potatoes. Here we report the antagonistic potential of these strains when co-cultivated with P. infestans as well as with other potato pathogens. We then focused on three Pseudomonas strains and compared their protective impact against late blight to that of well-known biocontrol strains in planta using a high-throughput leaf disk assay with automated picture analysis. When sprayed on the leaves of potatoes in the greenhouse, the strains were able to survive for at least 15 days. Under field conditions, populations decreased faster but all tested strains could still be retrieved after 8 days. The most active strain in vitro, P. chlororaphis R47, was also the best protectant on leaf disks from plants grown in the greenhouse experiment, but its protection potential could not be verified in the field due to unfavorable infection conditions. However, its protective effect against P. infestans in planta, its survival in the phyllosphere as well as its ability to colonize the potato rhizosphere in very high population densities, suggest a potential for field application, e.g., in the form of tuber treatment or leaf spray. PMID:26640460

  13. Isolation and characterization of a novel deoxynivalenol-transforming strain Paradevosia shaoguanensis DDB001 from wheat field soil.

    PubMed

    Wang, Y; Zhang, H H; Zhao, C; Han, Y T; Liu, Y C; Zhang, X L

    2017-08-11

    A Strain DDB001 having an ability to remove deoxynivalenol (DON) was successfully isolated from wheat field soil. On the basis of phenotypic, genotypic and phylogenetic data, the strain DDB001 was identified as Paradevosia shaoguanensis. Strain DDB001 could grow well and thoroughly eliminate 200 mg l(-1) of DON in complete growth medium, but it could not utilize DON as the sole carbon source for growth in mineral salt medium. Analysing DON transformation products by HPLC-MS assumed that the strain could transform DON into a less toxic stereoisomer, 3-epi-deoxynivalenol (3-epi-DON). In addition, it did not require preincubation with DON for the expression of DON-transforming activity. To the best of our knowledge, this is the first report showing that a Paradevosia strain has the capability of DON-transforming. Therefore, strain DDB001 can be considered as a useful tool in feed decontamination. Deoxynivalenol (DON) is one of the most frequently found mycotoxins in all major cereal grains worldwide. A DON-transforming bacterium, Paradevosia shaoguanensis DDB001, was isolated from wheat field soil. This study is the first report on isolation of a member of the genus Paradevosia as a potent DON-transformation micro-organism. The isolated bacterium has the potential to be utilized for detoxification of DON-contaminated feed. © 2017 The Society for Applied Microbiology.

  14. Giant Electric-Field-Induced Strain in PVDF-Based Battery Separator Membranes Probed by Electrochemical Strain Microscopy.

    PubMed

    Romanyuk, Konstantin; Costa, Carlos M; Luchkin, Sergey Yu; Kholkin, Andrei L; Lanceros-Méndez, Senentxu

    2016-05-31

    Efficiency of lithium-ion batteries largely relies on the performance of battery separator membrane as it controls the mobility and concentration of Li-ions between the anode and cathode electrodes. Recent advances in electrochemical strain microscopy (ESM) prompted the study of Li diffusion and transport at the nanoscale via electromechanical strain developed under an application of inhomogeneous electric field applied via the sharp ESM tip. In this work, we observed unexpectedly high electromechanical strain developed in polymer membranes based on porous poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) and, using it, could study a dynamics of electroosmotic flow of electrolyte inside the pores. We show that, independently of the separator membrane, electric field-induced deformation observed by ESM on wetted membrane surfaces can reach up to 10 nm under a moderate bias of 1 V (i.e., more than an order of magnitude higher than that in best piezoceramics). Such a high strain is explained by the electroosmotic flow in a porous media composed of PVDF. It is shown that the strain-based ESM method can be used to extract valuable information such as average pore size, porosity, elasticity of membrane in electrolyte solvent, and membrane-electrolyte affinity expressed in terms of zeta potential. Besides, such systems can, in principle, serve as actuators even in the absence of apparent piezoelectricity in amorphous PVDF.

  15. Construction of a bioluminescent reporter strain to detect polychlorinated biphenyls

    SciTech Connect

    Layton, A.C.; Muccini, M.; Ghosh, M.M.; Sayler, G.S.

    1998-12-01

    A bioluminescent reporter strain, Ralstonia eutropha ENV307 (pUTK60), was constructed for the detection of polychlorinated biphenyls by inserting the biphenyl promoter upstream of the bioluminescence genes. In the presence of a nonionic surfactant, which enhances the solubility of chlorinated biphenyls, bioluminescence was induced three- to fourfold over background by biphenyl, monochlorinated biphenyls, and Aroclor 1242. The minimum detection limits for these compounds ranged from 0.15 mg/liter for 4-chlorobiphenyl to 1.5 mg/liter for Aroclor 1242.

  16. Large field-induced strains in a lead-free piezoelectric material.

    PubMed

    Zhang, J X; Xiang, B; He, Q; Seidel, J; Zeches, R J; Yu, P; Yang, S Y; Wang, C H; Chu, Y-H; Martin, L W; Minor, A M; Ramesh, R

    2011-02-01

    Piezoelectric materials exhibit a mechanical response to electrical inputs, as well as an electrical response to mechanical inputs, which makes them useful in sensors and actuators. Lead-based piezoelectrics demonstrate a large mechanical response, but they also pose a health risk. The ferroelectric BiFeO(3) is an attractive alternative because it is lead-free, and because strain can stabilize BiFeO(3) phases with a structure that resembles a morphotropic phase boundary. Here we report a reversible electric-field-induced strain of over 5% in BiFeO(3) films, together with a characterization of the origins of this effect. In situ transmission electron microscopy coupled with nanoscale electrical and mechanical probing shows that large strains result from moving the boundaries between tetragonal- and rhombohedral-like phases, which changes the phase stability of the mixture. These results demonstrate the potential of BiFeO(3) as a substitute for lead-based materials in future piezoelectric applications.

  17. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    DOE PAGES

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; ...

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It ismore » found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.« less

  18. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    SciTech Connect

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; Lu, Zhaoping; George, Easo P.; Gao, Yanfei

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It is found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.

  19. Male Mating Competitiveness of a Wolbachia-Introgressed Aedes polynesiensis Strain under Semi-Field Conditions

    PubMed Central

    Bossin, Hervé; Dobson, Stephen L.

    2011-01-01

    Background Lymphatic filariasis (LF), a global public health problem affecting approximately 120 million people worldwide, is a leading cause of disability in the developing world including the South Pacific. Despite decades of ongoing mass drug administration (MDA) in the region, some island nations have not yet achieved the threshold levels of microfilaremia established by the World Health Organization for eliminating transmission. Previously, the generation of a novel Aedes polynesiensis strain (CP) infected with an exogenous type of Wolbachia has been described. The CP mosquito is cytoplasmically incompatible (i.e., effectively sterile) when mated with wildtype mosquitoes, and a strategy was proposed for the control of A. polynesiensis populations by repeated, inundative releases of CP males to disrupt fertility of wild females. Such a strategy could lead to suppression of the vector population and subsequently lead to a reduction in the transmission of filarial worms. Methodology/Principal Findings CP males and F1 male offspring from wild-caught A. polynesiensis females exhibit near equal mating competitiveness with F1 females under semi-field conditions. Conclusions/Significance While laboratory experiments are important, prior projects have demonstrated the need for additional testing under semi-field conditions in order to recognize problems before field implementation. The results reported here from semi-field experiments encourage forward progression toward small-scale field releases. PMID:21829750

  20. Male mating competitiveness of a Wolbachia-introgressed Aedes polynesiensis strain under semi-field conditions.

    PubMed

    Chambers, Eric W; Hapairai, Limb; Peel, Bethany A; Bossin, Hervé; Dobson, Stephen L

    2011-08-01

    Lymphatic filariasis (LF), a global public health problem affecting approximately 120 million people worldwide, is a leading cause of disability in the developing world including the South Pacific. Despite decades of ongoing mass drug administration (MDA) in the region, some island nations have not yet achieved the threshold levels of microfilaremia established by the World Health Organization for eliminating transmission. Previously, the generation of a novel Aedes polynesiensis strain (CP) infected with an exogenous type of Wolbachia has been described. The CP mosquito is cytoplasmically incompatible (i.e., effectively sterile) when mated with wildtype mosquitoes, and a strategy was proposed for the control of A. polynesiensis populations by repeated, inundative releases of CP males to disrupt fertility of wild females. Such a strategy could lead to suppression of the vector population and subsequently lead to a reduction in the transmission of filarial worms. CP males and F1 male offspring from wild-caught A. polynesiensis females exhibit near equal mating competitiveness with F1 females under semi-field conditions. While laboratory experiments are important, prior projects have demonstrated the need for additional testing under semi-field conditions in order to recognize problems before field implementation. The results reported here from semi-field experiments encourage forward progression toward small-scale field releases.

  1. Rotation and strain rate of Sulawesi from geometrical velocity field

    NASA Astrophysics Data System (ADS)

    Sarsito, D. A.; Susilo, Simons, W. J. F.; Abidin, H. Z.; Sapiie, B.; Triyoso, W.; Andreas, H.

    2017-07-01

    One of methods that can be used to determine the tectonic deformation status is rate estimation from geometric rotation and strain using quantitative velocity data from GPS observations. Microplate Sulawesi region located in the zone of triple junction (Eurasia, Australia and Philippine Sea Plates) has very complex tectonic and seismic condition, which is why become very important to know its recent deformation status in order to study neo-tectonic and disaster mitigation. Deformation rate quantification is estimated in two parameters: rotation and geodetic strain rate of each GPS station Delaunay triangle in the study area. The analysis in this study is not done using the grids since there is no rheological information at location that can be used as the interpolation-extrapolation constraints. Our analysis reveals that Sulawesi is characterized by rapid rotation in several different domains and compression-strain pattern that varies depending on the type and boundary conditions of microplate. This information is useful for studying neo tectonic deformation status and earthquake disaster mitigation.

  2. Dielectric breakdown field of strained silicon under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Kim, Chiho; Ramprasad, Rampi

    2017-09-01

    First-principles density functional theory calculations are used to reveal a quantitative relationship between the dielectric breakdown field and hydrostatic pressure of crystalline Si. The electronic band structure, phonon dispersion, and electron scattering rate are computed for pressures from 62.2 kbar (compressive) to -45.6 kbar (tensile) to estimate the rate of kinetic energy gain and loss for the electron. The theoretical dielectric breakdown fields are then determined using the von Hippel-Fröhlich criterion. Compressive stresses lead to a lower breakdown field, while significant increases in the dielectric breakdown field can be achieved by tensile stresses.

  3. Strain and Magnetic Field Induced Spin-Structure Transitions in Multiferroic BiFeO3.

    PubMed

    Agbelele, A; Sando, D; Toulouse, C; Paillard, C; Johnson, R D; Rüffer, R; Popkov, A F; Carrétéro, C; Rovillain, P; Le Breton, J-M; Dkhil, B; Cazayous, M; Gallais, Y; Méasson, M-A; Sacuto, A; Manuel, P; Zvezdin, A K; Barthélémy, A; Juraszek, J; Bibes, M

    2017-03-01

    The magnetic-field-dependent spin ordering of strained BiFeO3 films is determined using nuclear resonant scattering and Raman spectroscopy. The critical field required to destroy the cycloidal modulation of the Fe spins is found to be significantly lower than in the bulk, with appealing implications for field-controlled spintronic and magnonic devices.

  4. Full field stress/strain analysis : use of Moire and TSA for wood structural assemblies

    Treesearch

    R. W. Wolfe; R. E. Rowlands; C. H. Lin

    1994-01-01

    Laboratory and field experiments in wood engineering often rely on different types of devices to measure strain. Each type has certain limitations and characteristics that generally dictate its applicability to wood. Some of the issues related to using traditional strain measurement devices on wood and wood-based materials are discussed in this paper.

  5. Cyromazine resistance in a field strain of house flies, Musca domestica L.: Resistance risk assessment and bio-chemical mechanism.

    PubMed

    Khan, Hafiz Azhar Ali; Akram, Waseem

    2017-01-01

    Developing resistance management strategies for eco-friendly insecticides is essential for the management of insect pests without harming the environment. Cyromazine is a biorational insecticide with very low mammalian toxicity. Resistance to cyromazine has recently been reported in house flies from Punjab, Pakistan. In order to propose a resistance management strategy for cyromazine, experiments were planned to study risk for resistance development, possibility of cross-resistance and bio-chemical mechanisms. A field strain of house flies with 8.78 fold resistance ratio (RR) to cyromazine was re-selected under laboratory conditions. After seven rounds of selection (G1-G7), the RR values rapidly increased from 8.8 to 211 fold. However, these values declined to 81fold when the cyromazine selected (CYR-SEL) strain was reared without selection pressure, suggesting an unstable nature of resistance. The CYR-SEL strain showed lack of cross-resistance to pyriproxyfen, diflubenzuron, and methoxyfenozide. Synergism bioassays using enzyme inhibitors: piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF), and metabolic enzyme analyses revealed increased activity of carboxylesterase (CarE) and mixed-function oxidase (MFO) in the CYR-SEL strain compared to the laboratory susceptible (Lab-susceptible) strain, suggesting the metabolic resistance mechanism responsible for cyromazine resistance in the CYR-SEL strain. In conclusion, risk of rapid development of cyromazine resistance under consistent selection pressure discourages the sole reliance on cyromazine for controlling house flies in the field. The unstable nature of cyromazine resistance provides window for restoring cyromazine susceptibility by uplifting selection pressure in the field. Moreover, lack of cross-resistance between cyromazine and pyriproxyfen, diflubenzuron, or methoxyfenozide in the CYR-SEL strain suggest that cyromazine could be rotated with these insecticides whenever resistance crisis occur

  6. Field methods to measure surface displacement and strain with the Video Image Correlation method

    NASA Technical Reports Server (NTRS)

    Maddux, Gary A.; Horton, Charles M.; Mcneill, Stephen R.; Lansing, Matthew D.

    1994-01-01

    The objective of this project was to develop methods and application procedures to measure displacement and strain fields during the structural testing of aerospace components using paint speckle in conjunction with the Video Image Correlation (VIC) system.

  7. Effect of strain field on displacement cascade in tungsten studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Wang, D.; Gao, N.; Wang, Z. G.; Gao, X.; He, W. H.; Cui, M. H.; Pang, L. L.; Zhu, Y. B.

    2016-10-01

    Using atomistic methods, the coupling effect of strain field and displacement cascade in body-centered cubic (BCC) tungsten is directly simulated by molecular dynamics (MD) simulations at different temperatures. The values of the hydrostatic and uniaxial (parallel or perpendicular to primary knock-on atom (PKA) direction) strains are from -2% to 2% and the temperature is from 100 to 1000 K. Because of the annealing effect, the influence of strain on radiation damage at low temperature has been proved to be more significant than that at high temperature. When the cascade proceeds under the hydrostatic strain, the Frenkel Pair (FP) production, the fraction of defect in cluster and the average size of the defect cluster, all increase at tensile state and decrease at compressive state. When the cascade is under uniaxial strain, the effect of strain parallel to PKA direction is less than the effect of hydrostatic strain, while the effect of strain perpendicular to PKA direction can be negligible. Under the uniaxial strain along <1 1 1> direction, the SIA and SIA cluster is observed to orientate along the strain direction at tensile state and the uniaxial compressive strain with direction perpendicular to <1 1 1> has led to the similar preferred nucleation. All these results indicate that under irradiation, the tensile state should be avoided for materials used in nuclear power plants.

  8. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    DOE PAGES

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heatmore » release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  9. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  10. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  11. Modelling of Drain Current in Tunnelling Field-Effect Transistor Based on Strained Armchair Graphene Nanoribbons

    NASA Astrophysics Data System (ADS)

    Suhendi, E.; Syariati, R.; Noor, F. A.; Khairurrijal

    2017-03-01

    A tunnelling field-effect transistor (TFET) based armchair graphenenanoribbons (AGNRs) with variation of uniaxial strain has been modeled. Bandgap of strained AGNR estimated by an extended tight binding method is applied to obtain electrical characteristics of a TFET under the quantum capacitance limit device approximation. Furthermore, the electron transmittance is calculated by utilizing the WKB (Wentzel–Kramers–Brillouin) approach. The obtained transmittance is then used to calculate the drain current by employing the Landauer formula. The results show that strain parameter has significant effect on the current. In other words, the electrical characteristics of AGNR TFET can be tuned by the strain of AGNR.

  12. Second-harmonic microscopy of strain fields around through-silicon-vias

    NASA Astrophysics Data System (ADS)

    Cho, Yujin; Shafiei, Farbod; Mendoza, B. S.; Lei, Ming; Jiang, Tengfei; Ho, P. S.; Downer, M. C.

    2016-04-01

    Through-Silicon-Vias (TSVs)—10 μm-diameter conducting rods that connect vertically stacked silicon layers—provide three dimensional circuit integration, but introduce strain in the surrounding silicon when thermally cycled. Here, we noninvasively probe strain fields around Cu TSVs in Si(001) using optical second-harmonic generation (SHG) microscopy. Results are compared with micro-Raman spectra of the strained regions. We find that SHG probes strain fields more quickly than Raman spectroscopy, while maintaining comparable sensitivity and spatial resolution, and avoiding the need for spectral analysis. Moreover, SHG is selectively sensitive to axial shear components uiz (i = x, y) of the strain tensor that are often neglected in Raman analysis. Thus, SHG complements Raman spectroscopy.

  13. Comparison of the pathogenicity of the USDA challenge virus strain to a field strain of infectious laryngotracheitis virus.

    PubMed

    Koski, Danielle M; Predgen, Ann S; Trampel, Darrell W; Conrad, Sandra K; Narwold, Debra R; Hermann, Joseph R

    2015-07-01

    Infectious laryngotracheitis virus (ILTV) causes respiratory disease in chickens. This alphaherpesvirus infects laryngeal tracheal epithelial cells and causes outbreaks culminating in decreases in egg production, respiratory distress in chickens and mortality. There are several different vaccines to combat symptoms of the virus, including chicken embryo origin, tissue culture origin and recombinant vaccines. All vaccines licensed for use in the U.S. are tested for efficacy and potency according to U.S. federal regulation using a vaccine challenge assay involving the use of an ILT challenge virus. This challenge virus is provided to biologics companies by the Center for Veterinary Biologics (CVB), United States Department of Agriculture (USDA). The current USDA challenge virus originated from a vaccine strain and has been subjected to multiple passages in eggs, and may not represent what is currently circulating in the field. The objective of this study was to evaluate and compare the pathogenicity of USDA's challenge virus strain to the pathogenicity of a recent ILT field isolate. Using the challenge virus and various dilutions of the field isolate, clinical signs, mortality and pathology were evaluated in chickens. Results indicate that the field isolate at a 1:20 dilution is comparable in pathogenicity to the USDA challenge virus at a 1:4 dilution, and that the ILTV field isolate is a viable candidate that could be used as a challenge virus when evaluating vaccine efficacy. Published by Elsevier Ltd.

  14. Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Usman, M.; Hill, C. D.; Rahman, R.; Klimeck, G.; Simmons, M. Y.; Rogge, S.; Hollenberg, L. C. L.

    2015-06-01

    Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and nonstatic screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric-field-dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multiqubit architectures, based on both strain only as well as hybrid (strain + field) control of qubits. The benefits of strain are uncovered by demonstrating that a hybrid control of qubits based on (001) compressive strain and in-plane (100 or 010) fields results in higher gate fidelities and or faster gate operations, for all of the four donor species considered (P, As, Sb, and Bi). The comparison between different donor species in strained environments further highlights the trends of hyperfine shifts, providing predictions where no experimental data exists. While faster gate operations are realizable with in-plane fields for P, As, and Sb donors, only for the Bi donor, our calculations predict faster gate response in the presence of both in-plane and out-of-plane fields, truly benefiting from the proposed planar field control mechanism of the hyperfine interactions.

  15. Whole-field thickness strain measurement using multiple camera digital image correlation system

    NASA Astrophysics Data System (ADS)

    Li, Junrui; Xie, Xin; Yang, Guobiao; Zhang, Boyang; Siebert, Thorsten; Yang, Lianxiang.

    2017-03-01

    Three Dimensional digital image correlation(3D-DIC) has been widely used by industry, especially for strain measurement. The traditional 3D-DIC system can accurately obtain the whole-field 3D deformation. However, the conventional 3D-DIC system can only acquire the displacement field on a single surface, thus lacking information in the depth direction. Therefore, the strain in the thickness direction cannot be measured. In recent years, multiple camera DIC (multi-camera DIC) systems have become a new research topic, which provides much more measurement possibility compared to the conventional 3D-DIC system. In this paper, a multi-camera DIC system used to measure the whole-field thickness strain is introduced in detail. Four cameras are used in the system. two of them are placed at the front side of the object, and the other two cameras are placed at the back side. Each pair of cameras constitutes a sub stereo-vision system and measures the whole-field 3D deformation on one side of the object. A special calibration plate is used to calibrate the system, and the information from these two subsystems is linked by the calibration result. Whole-field thickness strain can be measured using the information obtained from both sides of the object. Additionally, the major and minor strain on the object surface are obtained simultaneously, and a whole-field quasi 3D strain history is acquired. The theory derivation for the system, experimental process, and application of determining the thinning strain limit based on the obtained whole-field thickness strain history are introduced in detail.

  16. Salmonella Gallinarum field isolates from laying hens are related to the vaccine strain SG9R.

    PubMed

    Van Immerseel, F; Studholme, D J; Eeckhaut, V; Heyndrickx, M; Dewulf, J; Dewaele, I; Van Hoorebeke, S; Haesebrouck, F; Van Meirhaeghe, H; Ducatelle, R; Paszkiewicz, K; Titball, R W

    2013-10-09

    Salmonella enterica subspecies enterica serotype Gallinarum can cause severe systemic disease in chickens and a live Salmonella Gallinarum 9R vaccine (SG9R) has been used widely to control disease. Using whole-genome sequencing we found point mutations in the pyruvate dehydrogenase (aceE) and/or lipopolysaccharide 1,2-glucosyltransferase (rfaJ) genes that likely explain the attenuation of the SG9R vaccine strain. Molecular typing using Pulsed Field Gel Electrophoresis and Multiple-Locus Variable number of tandem repeat Analysis showed that strains isolated from different layer flocks in multiple countries and the SG9R vaccine strain were similar. The genome of one Salmonella Gallinarum field strain, isolated from a flock with a mortality peak and selected on the basis of identical PFGE and MLVA patterns with SG9R, was sequenced. We found 9 non-silent single-nucleotide differences distinguishing the field strain from the SG9R vaccine strain. Our data show that a Salmonella Gallinarum field strain isolated from laying hens is almost identical to the SG9R vaccine. Mutations in the aceE and rfaJ genes could explain the reversion to a more virulent phenotype. Our results highlight the importance of using well defined gene deletion mutants as vaccines.

  17. Array-Based Genomic Comparative Hybridization Analysis of Field Strains of Mycoplasma hyopneumoniae▿ †

    PubMed Central

    Madsen, Melissa L.; Oneal, Michael J.; Gardner, Stuart W.; Strait, Erin L.; Nettleton, Dan; Thacker, Eileen L.; Minion, F. Chris

    2007-01-01

    Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia and a major factor in the porcine respiratory disease complex. A clear understanding of the mechanisms of pathogenesis does not exist, although it is clear that M. hyopneumoniae adheres to porcine ciliated epithelium by action of a protein called P97. Previous studies have shown variation in the gene encoding the P97 cilium adhesin in different strains of M. hyopneumoniae, but the extent of genetic variation among field strains across the genome is not known. Since M. hyopneumoniae is a worldwide problem, it is reasonable to expect that a wide range of genetic variability may exist given all of the different breeds and housing conditions. This variation may impact the overall virulence of a single strain. Using microarray technology, this study examined the potential variation of 14 field strains compared to strain 232, on which the array was based. Genomic DNA was obtained, amplified with TempliPhi, and labeled indirectly with Alexa dyes. After genomic hybridization, the arrays were scanned and data were analyzed using a linear statistical model. The results indicated that genetic variation could be detected in all 14 field strains but across different loci, suggesting that variation occurs throughout the genome. Fifty-nine percent of the variable loci were hypothetical genes. Twenty-two percent of the lipoprotein genes showed variation in at least one field strain. A permutation test identified a location in the M. hyopneumoniae genome where there is spatial clustering of variability between the field strains and strain 232. PMID:17873054

  18. Misleading Performance Reporting in the Supercomputing Field

    NASA Technical Reports Server (NTRS)

    Bailey, David H.; Kutler, Paul (Technical Monitor)

    1992-01-01

    In a previous humorous note, I outlined twelve ways in which performance figures for scientific supercomputers can be distorted. In this paper, the problem of potentially misleading performance reporting is discussed in detail. Included are some examples that have appeared in recent published scientific papers. This paper also includes some proposed guidelines for reporting performance, the adoption of which would raise the level of professionalism and reduce the level of confusion in the field of supercomputing.

  19. Perceptual and physiological heat strain: examination in firefighters in laboratory- and field-based studies.

    PubMed

    Petruzzello, S J; Gapin, J I; Snook, E; Smith, D L

    2009-06-01

    Firefighting demands performing heavy muscular work under adverse and potentially dangerous conditions. Although the physiological and psychological responses to simulated firefighting activities have been described, the heat strain has not been characterised using standardised indices of exercise-heat strain. The purpose of the study is to describe the physiological and perceptual strain associated with working in personal protective equipment and performing simulated firefighting activities in a hot environment using recently developed strain indices (Physiological Strain Index (PhSI); Perceptual Strain Index (PeSI)). Data from two previously published studies (Smith et al. 1995, 2001) - one a laboratory-based study and one a field-based study - were re-analysed incorporating the strain indices. The laboratory study involved walking on a treadmill for 15 min while wearing three different clothing and equipment configurations. The field study involved three trials of standardised firefighting tasks in a live-fire training structure (mean trial length = 5.76 min). Heart rate, rectal temperature, thermal sensations and ratings of perceived exertion were collected in each study. PhSI and PeSI values were calculated using the formulae developed by Moran et al. (1998b) and Tikuisis et al. (2002), respectively. PhSI and PeSI increased significantly over time in both studies. Even relatively brief bouts of exercise while wearing heavy impermeable clothing or simulated firefighting activity in the heat results in moderate to high levels of heat strain as assessed by PhSI and PeSI.

  20. Effect of extended strain fields on point defect phonon scattering in thermoelectric materials

    SciTech Connect

    Ortiz, Brenden R.; Peng, Haowei; Lopez, Armando; Parilla, Philip A.; Lany, Stephan; Toberer, Eric S.

    2015-01-01

    The design of thermoelectric materials often involves the integration of point defects (alloying) as a route to reduce the lattice thermal conductivity. Classically, the point defect scattering strength follows from simple considerations such as mass contrast and the presence of induced strain fields (e.g. radius contrast, coordination changes). While the mass contrast can be easily calculated, the associated strain fields induced by defect chemistry are not readily predicted and are poorly understood. In this work, we use classical and first principles calculations to provide insight into the strain field component of phonon scattering from isoelectronic point defects. Our results also integrate experimental measurements on bulk samples of SnSe and associated alloys with S, Te, Ge, Sr and Ba. These efforts highlight that the strength and extent of the resulting strain field depends strongly on defect chemistry. Strain fields can have a profound impact on the local structure. For example, in alloys containing Ba, the strain fields have significant spatial extent (1 nm in diameter) and produce large shifts in the atomic equilibrium positions (up to 0.5 A). Such chemical complexity suggests that computational assessment of point defects for thermal conductivity depression should be hindered. However, in this work, we present and verify several computational descriptors that correlate well with the experimentally measured strain fields. Furthermore, these descriptors are conceptually transparent and computationally inexpensive, allowing computation to provide a pivotal role in the screening of effective alloys. The further development of point defect engineering could complement or replace nanostructuring when optimizing the thermal conductivity, offering the benefits of thermodynamic stability, and providing more clearly defined defect chemistry.

  1. 3D geometry of the strain-field at transform plate boundaries: Implications for seismic rupture

    SciTech Connect

    Bodin, P.; Bilham, R. |

    1994-11-01

    We examine the amplitude and distribution of slip on vertical frictionless faults in the zone of concentrated shear strain that is characteristic of transform plate boundaries. We study both a 2D and a 3D approximation to this strain field. Mean displacements on ruptures within the zone of concentrated shear strain are proportional to the shear strain at failure when they are short, and are limited by plate displacements since the last major earthquake when they are long. The transition between these two behaviors occurs when the length of the dislocation approaches twice the thickness of the seismogenic crust, approximately the breadth of the zone of concentrated shear strain observed geodetically at transform plate boundaries. This result explains the observed non-linear scaling relation between seismic moment and rupture length. A geometrical consequence of the 3D model, in which the strain-field tapers downward, is that moderate earthquakes with rupture lengths similar to the thickness of the crust tend to slip more at depth than near the surface. Seismic moments estimated from surface slip in moderate earthquakes (M less than or equal to 7) will thus be underestimated. Shallow creep, if its along-strike dimension is extensive, can reduce a surface slip deficit that would otherwise develop on faults on which M less than 7 events are typical. In the absence of surface creep or other forms of off-fault deformation great earthquakes may be necessary features of transform boundaries with downward-tapering strain-fields.

  2. Local and nonlocal strain rate fields and vorticity alignment in turbulent flows.

    PubMed

    Hamlington, Peter E; Schumacher, Jörg; Dahm, Werner J A

    2008-02-01

    Local and nonlocal contributions to the total strain rate tensor S(ij) at any point x in a flow are formulated from an expansion of the vorticity field in a local spherical neighborhood of radius R centered on x. The resulting exact expression allows the nonlocal (background) strain rate tensor S(ij)(B)(x) to be obtained from S(ij)(x). In turbulent flows, where the vorticity naturally concentrates into relatively compact structures, this allows the local alignment of vorticity with the most extensional principal axis of the background strain rate tensor to be evaluated. In the vicinity of any vortical structure, the required radius R and corresponding order n to which the expansion must be carried are determined by the viscous length scale lambda(nu). We demonstrate the convergence to the background strain rate field with increasing R and n for an equilibrium Burgers vortex, and show that this resolves the anomalous alignment of vorticity with the intermediate eigenvector of the total strain rate tensor. We then evaluate the background strain field S(ij)(B)(x) in direct numerical simulations of homogeneous isotropic turbulence where, even for the limited R and n corresponding to the truncated series expansion, the results show an increase in the expected equilibrium alignment of vorticity with the most extensional principal axis of the background strain rate tensor.

  3. Genomic characterization of a broiler reovirus field strain detected in Pennsylvania.

    PubMed

    Tang, Yi; Lu, Huaguang

    2015-04-01

    Avian reovirus (ARV) infections have been increasingly diagnosed in Pennsylvania (PA) from 2011 to the present time. A field ARV strain (Reo/PA/Broiler/05682/12) isolated from sick broilers suffered from severe arthritis/tenosynovitis of a PA broiler flock was conducted full genome sequence studies using RT-PCR and RACE techniques. The complete genome of the PA broiler ARV field strain was 23,494bp in length with an approximately 50% G+C content and 10 dsRNA segments encoding 12 viral proteins. The 10 genomic segments were ranged from 1192bp (S4) to 3958bp (L1) in length, which were almost identical to those of published reference strains. The amino acid (aa) alignments of the putative proteins encoded by the ORF in each segment revealed a high similarity to the counterpart proteins encoded by other avian orthoreoviruses in the Orthoreovirus genus, particularly with the reference strain AVS-B (89.4-98.9%). The phylogenetic analysis of the nucleotide sequences of all 10 genome segments of the PA broiler ARV revealed that a moderate to significant nucleotide sequence divergence from sequences of cognate genome segments of reference ARV S1133 and 138 strains. These genomic data demonstrate that this PA broiler ARV field strain is a unique tenosynovitis ARV and is different from the traditional ARV vaccine strains. Published by Elsevier B.V.

  4. Microbial control of Agrilus planipennis (Coleoptera: Buprestidae) with Beauveria bassiana strain GHA: field applications

    Treesearch

    Houping Liu; Leah S. Bauer

    2008-01-01

    The effects of Beauveria bassiana strain GHA, applied as BotaniGard ES, on newly colonised and well-established populations of emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) were evaluated in the field using foliar and trunk sprays in Michigan in 2004-2005. Results from field trials at a newly colonised white ash...

  5. Strain field reconstruction in shallow trench isolation structures by CBED and LACBED

    NASA Astrophysics Data System (ADS)

    Spessot, A.; Frabboni, S.; Balboni, R.; Armigliato, A.

    2006-12-01

    Using a combination of the CBED and the LACBED techniques in the transmission electron microscopy (TEM), we have investigated the strain field in the silicon active region of a shallow trench isolation structure, underlying a TiSi 2 layer. Starting from the analysis of the deformation in a sample, thinned for TEM analysis, we have reconstructed the displacement field, simulating the split HOLZ lines visible in the experimental CBED patterns. From the comparison between the experimental LACBED patterns, taken in a suitable sample orientation to evidence the stressors distribution in the polycrystalline silicide layer, and the corresponding dynamically simulated ones, we have reproduced the strain field in the unthinned, bulk sample.

  6. Draft Genome Sequence of the Field Isolate Brucella melitensis Strain Bm IND1 from India.

    PubMed

    Rao, Sashi Bhushan; Gupta, Vivek K; Kumar, Mukesh; Hegde, Nagendra R; Splitter, Gary A; Reddanna, Pallu; Radhakrishnan, Girish K

    2014-05-29

    Brucella spp. are facultative intracellular bacterial pathogens causing the zoonotic disease brucellosis. Here, we report the draft genome sequence of the Brucella melitensis strain from India designated Bm IND1, isolated from stomach contents of an aborted goat fetus.

  7. Direct Strain Tensor Approximation for Full-Field Strain Measurement Methods

    DTIC Science & Technology

    2013-01-01

    mathematical theory of elasticity. In fact, the general solution to this problem for an elliptic hole is known [35] and is implemented here for an ellipse of...noise. Because for the current digital imaging technology and for most practical applications , the accuracy in coordinate measurement is... applications where the knowledge of the uncertainty of the full-field measurements is of importance. 7. CONCLUSIONS In this work, the numerical foundation

  8. High-resolution melt PCR analysis for rapid identification of Chlamydia abortus live vaccine strain 1B among C. abortus strains and field isolates.

    PubMed

    Vorimore, Fabien; Cavanna, Noémie; Vicari, Nadia; Magnino, Simone; Willems, Hermann; Rodolakis, Annie; Siarkou, Victoria I; Laroucau, Karine

    2012-09-01

    We describe a novel high-resolution melt assay that clearly differentiates Chlamydia abortus live vaccine strain 1B from field C. abortus strains and field wild-type isolates based on previously described single nucleotide polymorphisms. This modern genotyping technique is inexpensive, easy to use, and less time-consuming than PCR-RFLP.

  9. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts

    PubMed Central

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S.

    2017-01-01

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2. PMID:28186113

  10. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts.

    PubMed

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S

    2017-02-10

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2.

  11. Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts

    NASA Astrophysics Data System (ADS)

    Chai, Yu; Su, Shanshan; Yan, Dong; Ozkan, Mihrimah; Lake, Roger; Ozkan, Cengiz S.

    2017-02-01

    Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25 eV, the band gap decreases as the tensile strain increases on an average of ~100 meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2.

  12. Interrelationship between flexoelectricity and strain gradient elasticity in ferroelectric nanofilms: A phase field study

    NASA Astrophysics Data System (ADS)

    Jiang, Limei; Xu, Xiaofei; Zhou, Yichun

    2016-12-01

    With the development of the integrated circuit technology and decreasing of the device size, ferroelectric films used in nano ferroelectric devices become thinner and thinner. Along with the downscaling of the ferroelectric film, there is an increasing influence of two strain gradient related terms. One is the strain gradient elasticity and the other one is flexoelectricity. To investigate the interrelationship between flexoelectricity and strain gradient elasticity and their combined effect on the domain structure in ferroelectric nanofilms, a phase field model of flexoelectricity and strain gradient elasticity on the ferroelectric domain evolution is developed based on Mindlin's theory of strain-gradient elasticity. Weak form is derived and implemented in finite element formulations for numerically solving the model equations. The simulation results show that upper bounds for flexoelectric coefficients can be enhanced by increasing strain gradient elasticity coefficients. While a large flexoelectricity that exceeds the upper bound can induce a transition from a ferroelectric state to a modulated/incommensurate state, a large enough strain gradient elasticity may lead to a conversion from an incommensurate state to a ferroelectric state. Strain gradient elasticity and the flexoelectricity have entirely opposite effects on polarization. The observed interrelationship between the strain gradient elasticity and flexoelectricity is rationalized by an analytical solution of the proposed theoretical model. The model proposed in this paper could help us understand the mechanism of phenomena observed in ferroelectric nanofilms under complex electromechanical loads and provide some guides on the practical application of ferroelectric nanofilms.

  13. Mapping the three-dimensional strain field around a microindentation on silicon using polishing and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Puech, Pascal; Pinel, Stéphane; Jasinevicius, Renato G.; Pizani, Paolo Sergio

    2000-10-01

    The strain field around a Vickers microindentation of crystalline silicon (001) has been mapped using Raman spectroscopy. The nature of the three-dimensional strain field of the microindentation was determined by comparing the parallel and crossed scattering geometries and applying the relations between the optical phonon frequency shift and strain. A surface layer (2 μm) was then removed by abrasive chemical polishing. The strain is preserved by the polishing process and information on microindentation depth is obtained. The produced maps give a good idea of the strain field after unloading. We find a quasicircular zone of plastic deformation where the strain follows a 1/r law.

  14. A high accuracy automated strain-field mapper

    SciTech Connect

    James, M.R.; Morris, W.L.; Cox, B.N. )

    1990-03-01

    The design and capabilities of a computer-automated high-spatial-resolution displacement-measurement system are described. The system is used to determine the relative displacement fields generated by thermal or mechanical loads by comparing a pair of SEM or optical micrographs, one recorded before the load is applied and the other afterwards. The displacements are measured by cross-correlation analysis of the relative positions of visible surface texture on the micrographs. Displacement accuracy on a specimen surface is + or - 60 A for optical microscopy, and + or - 10 A for SEM. Both in-plane or out-of-plane deformation can be characterized, depending on the angle at which the specimen is viewed. This instrument has the potential of quantifying surface deformation over submicron-gage lengths and will be an invaluable tool in experimental micromechanics. 15 refs.

  15. Focus on the electrical field-induced strain of electroactive polymers and the observed saturation

    NASA Astrophysics Data System (ADS)

    Guyomar, D.; Yuse, K.; Cottinet, P.-J.; Kanda, M.; Lebrun, L.

    2010-12-01

    Thanks to their large electrical field-induced strains, electroactive polymers can be used in various applications; as electroactive materials for artificial muscles or as active materials of membranes, due to their flexibility. One drawback concerning their use involves the saturation of the electrical field-induced strain which occurs at around 20% for a polymer film with a thickness of 80 μm. Few studies have been devoted to the understanding of this saturation. To this end, the present paper describes mechanical measurements of the extensive strain versus stress and the determination of the current flowing through an electroactive polymer driven by an electrical field. These experiments have clearly demonstrated that the observed saturation of the electrical induced strain was not due to a mechanical saturation within the sample but to the saturation of the electrically induced polarization. By carrying out a suitable modeling of the polarization versus electrical field, it was possible to calculate the strain and current versus electrical field. These values were then compared to experimental data, and were found to show a very good agreement.

  16. Micromotion-induced strain fields influence early stages of repair at bone-implant interfaces

    PubMed Central

    Wazen, Rima M.; Currey, Jennifer A.; Guo, Hongqiang; Brunski, John B.; Helms, Jill A.; Nanci, Antonio

    2013-01-01

    Implant loading can create micromotion at the bone-implant interface. The interfacial strain associated with implant micromotion could contribute to regulating the tissue healing response. Excessive micromotion can lead to fibrous encapsulation and implant loosening. Our objective was to characterize the influence of interfacial strain on bone regeneration around implants in mouse tibiae. A micromotion system was used to create strain under conditions of (1) no initial contact between implant and bone, and (2) a direct bone-implant contact. Pin- and screw-shaped implants were subjected to displacements of 150 μm or 300 μm, 60 cycles/day, for 7 days. Pin-shaped implants placed in 5 animals were subjected to 3 sessions of 150 μm displacement per day, with 60 cycles per session. Control implants in both types of interfaces were stabilized throughout the healing period. Experimental strain analyses, microtomography, image-based displacement mapping, and finite element simulations were used to characterize interfacial strain fields. Calcified tissue sections were prepared and stained with Goldner to evaluate tissue reaction in higher and lower strain regions. In stable implants, bone formation occurred consistently around the implants. In implants subjected to micromotion, bone regeneration was disrupted in areas of high strain concentrations (e.g. > 30%), whereas lower strain values were permissive of bone formation. Increasing implant displacement or number of cycles per day also changed the strain distribution and disturbed bone healing. These results indicate that not only implant micromotion but also the associated interfacial strain field contributes to regulating the interfacial mechanobiology at healing bone-implant interfaces. PMID:23337705

  17. Strain of optic-fiber/giant magnetostrictive film structure in magnetic field by finite element analysis

    NASA Astrophysics Data System (ADS)

    Hu, Jiafei; Pan, Mengchun; Xin, Jianguang; Chen, Dixiang

    2008-12-01

    The magnetostrictive transducer is the most important part of the optic-fiber magnetic field sensor, and the optic-fiber/giant magnetostrictive(GMS) film coupled structure is a novel coupling form of the magnetostrictive transducer. Always we analyze the coupled structure based on the entire coupled structure being sputtered GMS material without tail-fibers. In practical application, the coupled structure has tail-fibers without films at two ends. When the entire coupled structure is immersed in the detected magnetic field, the detected magnetic field causes the GMS film strain then causing optic-fiber strain. This strain transmission process is different from it in the coupled structure entirely with GMS films without tail-fibers. The strain transmission relationship can be calculated theoretically in the coupled structure without tail-fibers, but it's complicated to theoretically calculate the strain transmission relationship in the coupled structure with tail-fibers. After large numbers of calculations and analyses by ANSYS software, we figure out some relationships of the two strain transmission processes in the respective structures and the stress distribution in the tail-fibers. These results are helpful to the practical application of the optic-fiber/ GMS film coupled structure.

  18. 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.

  19. Characterization of dynamic three-dimensional strain fields in the canine radius.

    PubMed

    Coleman, John C; Hart, Richard T; Owan, Ichiro; Tankano, Yuichi; Burr, David B

    2002-12-01

    This note describes a method to approximate the 3-D mechanical environment of a long bone during a normal daily activity. Our specific goal was to characterize the temporal and spatial strain distributions in the mid-shaft region of the canine radius during gait. Direct measurement of strains along the entire surface of in vivo bone is not feasible, so we employed a combination of experimental measurements and numerical interpolation techniques to approximate the time-varying longitudinal strain distribution. Using standard in vivo strain gauging techniques, we measured dynamic strains at nine locations (three locations on each of three cross sections, data pooled from two experimental animals) on the canine radius during trotting gait. These in vivo strain measurements were then used to approximate the time course of the strain field for the entire radius mid-shaft region using a 3-D numerical interpolation scheme using finite element basis functions. Despite limitations in the present implementation of the method, the results show that there are considerable time-dependent variations in the strain distribution occurring at different transverse sections along the length of the diaphysis with substantial anteroposterior bending and rotation of neutral axis locations during the gait cycle.

  20. Low-Field-Triggered Large Magnetostriction in Iron-Palladium Strain Glass Alloys

    NASA Astrophysics Data System (ADS)

    Ren, Shuai; Xue, Dezhen; Ji, Yuanchao; Liu, Xiaolian; Yang, Sen; Ren, Xiaobing

    2017-09-01

    Development of miniaturized magnetostriction-associated devices requires low-field-triggered large magnetostriction. In this study, we acquired a large magnetostriction (800 ppm) triggered by a low saturation field (0.8 kOe) in iron-palladium (Fe-Pd) alloys. Magnetostriction enhancement jumping from 340 to 800 ppm was obtained with a slight increase in Pd concentration from 31.3 to 32.3 at. %. Further analysis showed that such a slight increase led to suppression of the long-range ordered martensitic phase and resulted in a frozen short-range ordered strain glass state. This strain glass state possessed a two-phase nanostructure with nanosized frozen strain domains embedded in the austenite matrix, which was responsible for the unique magnetostriction behavior. Our study provides a way to design novel magnetostrictive materials with low-field-triggered large magnetostriction.

  1. Improved thermoelectric properties of TiNiSn through enhancing strain field fluctuation

    NASA Astrophysics Data System (ADS)

    Lkhagvasuren, Enkhtaivan; Fu, Chenguang; Fecher, Gerhard H.; Auffermann, Gudrun; Kreiner, Guido; Schnelle, Walter; Felser, Claudia

    2017-10-01

    MNiSn (M  =  Hf, Zr, Ti) -based half Heusler compounds have attracted extensive attention as promising materials in thermoelectric power generation. In this work, the thermoelectric properties of the cheapest composition TiNiSn from this system are investigated. Isoelectronic substitutions of Si and Ge on Sn site are employed to reduce the lattice thermal conductivity. It is found that Si substitution leads to simultaneously enhanced mass and strain field fluctuations in TiNiSn, while the strain field fluctuation dominates the decrease of thermal conductivity in Ge substituted TiNiSn. A maximum ZT of 0.48 at 740 K is obtained in TiNiSn0.975 Ge0.025 , which is a 23% increase compared to TiNiSn. This result highlights the role of strain field fluctuation in suppressing lattice thermal conductivity and improving the thermoelectric performance of half-Heusler compounds.

  2. Controlling the exciton energy of a nanowire quantum dot by strain fields

    SciTech Connect

    Chen, Yan; Zhang, Jiaxiang; Ding, Fei; Zadeh, Iman Esmaeil; Jöns, Klaus D.; Fognini, Andreas; Zwiller, Val; Reimer, Michael E.; Dalacu, Dan; Poole, Philip J.; Schmidt, Oliver G.

    2016-05-02

    We present an experimental route to engineer the exciton energies of single quantum dots in nanowires. By integrating the nanowires onto a piezoelectric crystal, we controllably apply strain fields to the nanowire quantum dots. Consequently, the exciton energy of a single quantum dot in the nanowire is shifted by several meVs without degrading its optical intensity and single-photon purity. Second-order autocorrelation measurements are performed at different strain fields on the same nanowire quantum dot. The suppressed multi-photon events at zero time delay clearly verify that the quantum nature of single-photon emission is well preserved under external strain fields. The work presented here could facilitate on-chip optical quantum information processing with the nanowire based single photon emitters.

  3. Strain field evolution at the ductile-to-brittle transition: a case study on ice

    NASA Astrophysics Data System (ADS)

    Chauve, Thomas; Montagnat, Maurine; Lachaud, Cedric; Georges, David; Vacher, Pierre

    2017-09-01

    This paper presents, for the first time, the evolution of the local heterogeneous strain field around intra-granular cracking in polycrystalline ice, at the onset of tertiary creep. Owing to the high homologous temperature conditions and relatively low compressive stress applied, stress concentration at the crack tips is relaxed by plastic mechanisms associated with dynamic recrystallization. Strain field evolution followed by digital image correlation (DIC) directly shows the redistribution of strain during crack opening, but also the redistribution driven by crack tip plasticity mechanisms and recrystallization. Associated local changes in microstructure induce modifications of the local stress field evidenced by crack closure during deformation. At the ductile-to-brittle transition in ice, micro-cracking and dynamic recrystallization mechanisms can co-exist and interact, the later being efficient to relax stress concentration at the crack tips.

  4. Full-field, high-spatial-resolution detection of local structural damage from low-resolution random strain field measurements

    NASA Astrophysics Data System (ADS)

    Yang, Yongchao; Sun, Peng; Nagarajaiah, Satish; Bachilo, Sergei M.; Weisman, R. Bruce

    2017-07-01

    Structural damage is typically a local phenomenon that initiates and propagates within a limited area. As such high spatial resolution measurement and monitoring is often needed for accurate damage detection. This requires either significantly increased costs from denser sensor deployment in the case of global simultaneous/parallel measurements, or increased measurement time and labor in the case of global sequential measurements. This study explores the feasibility of an alternative approach to this problem: a computational solution in which a limited set of randomly positioned, low-resolution global strain measurements are used to reconstruct the full-field, high-spatial-resolution, two-dimensional (2D) strain field and rapidly detect local damage. The proposed approach exploits the implicit low-rank and sparse data structure of the 2D strain field: it is highly correlated without many edges and hence has a low-rank structure, unless damage-manifesting itself as sparse local irregularity-is present and alters such a low-rank structure slightly. Therefore, reconstruction of the full-field, high-spatial-resolution strain field from a limited set of randomly positioned low-resolution global measurements is modeled as a low-rank matrix completion framework and damage detection as a sparse decomposition formulation, enabled by emerging convex optimization techniques. Numerical simulations on a plate structure are conducted for validation. The results are discussed and a practical iterative global/local procedure is recommended. This new computational approach should enable the efficient detection of local damage using limited sets of strain measurements.

  5. Influence of strain and electric field on the properties of silicane

    NASA Astrophysics Data System (ADS)

    Cheng, Gang; Liu, Peng-Fei; Li, Zi-Tao

    2013-04-01

    We investigate the influence of strain and electric field on the properties of a silicane sheet. Some elastic parameters of silicane, such as an in-plane stiffness of 52.55 N/m and a Poisson's ratio of 0.24, are obtained by calculating the strain energy. Compared with silicene, silicane is softer because of its relatively weaker Si—Si bonds. The band structure of silicane is tunable by a uniform tensile strain, with the increase of which the band gap decreases monotonously. Moreover, silicane undergoes an indirect—direct gap transition under a small strain, and a semiconductor-metal transition under a large strain. The electric field can change the Si—H bond length of silicane significantly. When a strong field is applied, the H atom at the high potential side becomes desorbed, while the H atom at the low potential side keeps bonded. So an external electric field can help to produce single-side hydrogenated silicene from silicane. We believe this study will be helpful for the application of silicane in the future.

  6. Simultaneous assessment of Lagrangian strain and temperature fields by improved IR-DIC strategy

    NASA Astrophysics Data System (ADS)

    Wang, X. G.; Liu, C. H.; Jiang, C.

    2017-07-01

    This paper focuses on the development of a novel digital image correlation strategy based on infrared imaging (IR-DIC) for realizing simultaneous assessment of Lagrangian strain and temperature fields. A major difficulty in the IR-DIC is the evolution of the thermal field during deformation that is unexpected in the image correlation. Two solutions are proposed to tackle this difficulty. The first solution is to utilize a high-pass filter to eliminate the variation part of the thermal signal, and the second solution is to employ an advanced metric, the mutual information, as the correlation criterion. Both methods are verified through a tensile test performed on a notched specimen. The estimated displacement and strain fields demonstrate well the desirable performance of the proposed methods. Thanks to the kinematic field assessment, the obtained thermal fields can be described in the Lagrangian coordinate system, thus the temperature evolution of the material points during deformation can be followed effectively.

  7. Phototaxis in the magnetotactic bacterium Magnetospirillum magneticum strain AMB-1 is independent of magnetic fields.

    PubMed

    Chen, Chuanfang; Ma, Qiufeng; Jiang, Wei; Song, Tao

    2011-04-01

    Magnetotactic bacteria (MTB) can rapidly relocate to optimal habitats by magneto-aerotaxis. Little is known about MTB phototaxis, a response that might also aid navigation. In this study, we analyzed the relationship between phototaxis and magnetotaxis in Magnetospirillum magneticum strain AMB-1. Magnotactic AMB-1 cells migrated toward light, and migration increased with higher light intensity. This response was independent of wavelength, as AMB-1 cells migrated equally toward light from 400 to 750 nm. When AMB-1 cells were exposed to zero magnetic fields or to 0.2 mT magnetic fields that were opposite or orthogonal to the light beam, cells still migrated toward the light, indicating that phototaxis was independent of magnetotaxis. The R(mag) value and coercive force (H(c)) of AMB-1 increased when the bacteria were illuminated for 20 h, consistent with an increase in magnetosome synthesis or in magnetosome-containing cells. These results demonstrated that the M. magneticum AMB-1 responded to light as well as other environmental factors. To our knowledge, this is the first report of phototactic behavior in the bacteria of Magnetospirillum.

  8. Toxicity and Metabolism of Zeta-Cypermethrin in Field-Collected and Laboratory Strains of the Neotropical Predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae).

    PubMed

    Haramboure, M; Smagghe, G; Niu, J; Christiaens, O; Spanoghe, P; Alzogaray, R A

    2017-03-09

    Resistance to pesticides has been studied in several insect pests, but information on the natural enemies of pests-including the Neotropical predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae), a major biological control agent in South America-is lacking. We report here a comparative study between a field-collected strain of C. externa subjected to monthly sprayings of pyrethroids and neonicotinoids and a laboratory strain without exposure to pesticides. The tolerance of both strains against zeta-cypermethrin was similar, and addition of the synergist piperonyl butoxide increased the toxicity by 30% in both strains. Gas-chromatography analyses and mixed-function-oxidase measurements indicated similar values in both strains and also confirmed the key role of oxidative metabolism in this species. Because C. externa has maintained a tolerance to zeta-cypermethrin without previous pesticide exposure, this species could potentially be mass-reared and released in fields in the presence of pesticide pressure.

  9. Molecular characteristics of Polish field strains of Marek's disease herpesvirus isolated from vaccinated chickens

    PubMed Central

    2011-01-01

    Background Twenty-nine Marek's disease virus (MDV) strains were isolated during a 3 year period (2007-2010) from vaccinated and infected chicken flocks in Poland. These strains had caused severe clinical symptoms and lesions. In spite of proper vaccination with mono- or bivalent vaccines against Marek's disease (MD), the chickens developed symptoms of MD with paralysis. Because of this we decided to investigate possible changes and mutations in the field strains that could potentially increase their virulence. We supposed that such mutations may have been caused by recombination with retroviruses of poultry - especially reticuloendotheliosis virus (REV). Methods In order to detect the possible reasons of recent changes in virulence of MDV strains, polymerase chain reaction (PCR) analyses for meq oncogene and for long-terminal repeat (LTR) region of REV were conducted. The obtained PCR products were sequenced and compared with other MDV and REV strains isolated worldwide and accessible in the GeneBank database. Results Sequencing of the meq oncogene showed a 68 basepair insertion and frame shift within 12 of 24 field strains. Interestingly, the analyses also showed 0.78, 0.8, 0.82, 1.6 kb and other random LTR-REV insertions into the MDV genome in 28 of 29 of strains. These genetic inserts were present after passage in chicken embryo kidney cells suggesting LTR integration into a non-functional region of the MDV genome. Conclusion The results indicate the presence of a recombination between MDV and REV under field conditions in Polish chicken farms. The genetic changes within the MDV genome may influence the virus replication and its features in vivo. However, there is no evidence that meq alteration and REV insertions are related to the strains' virulence. PMID:21320336

  10. Strain hardening and ductility of iron: axisymmetric vs plane strain elongation. Technical progress report

    SciTech Connect

    Langford, G.

    1980-05-01

    The strain hardening of iron at high strains in plane strain elongation (strip drawing) is shown to fall increasingly below that of drawn iron wires at true strains above 2, going through zero strain hardening at epsilon = 3.0, and becoming strongly negative thereafter, at least up to epsilon = 4.1. High resolution selected area electron diffraction has been used to map the size, shape and crystallographic orientations of a group of about 50 contiguous cells centered around an incipient shear band in an edge section of a strip drawn to epsilon = 1.8. This map shows no textural instability or change in orientation associated with the shear band, although it does show substantial misorientations throughout the group of cells, the axis of these misorientations lying in the same direction as the trace of the shear band. No other large misorientations (i.e. 5/sup 0/ or so) are present. The only instability seen in this shear band is microstructural: the slip distances in the two primary slip directions are quite anisotropic, being much longer along the trace of the shear band. Note that this shear band has appeared during the linear hardening portion of the high-strain hardening curve of the drawn strip. It is therefore considered a direct weakening mechanism rather than a result of another weakening effect. Further such orientation maps have been or are being prepared for more highly deformed strip, and for wire and pure-shear specimens as well.

  11. Production of Apx toxins by field strains of Actinobacillus pleuropneumoniae and Actinobacillus suis.

    PubMed Central

    Kamp, E M; Vermeulen, T M; Smits, M A; Haagsma, J

    1994-01-01

    The three Apx toxins of Actinobacillus pleuropneumoniae have potential value for use in vaccines and diagnostic tests which will be species specific instead of serotype specific, provided that the Apx toxins are species specific and all field strains produce these toxins. We examined 114 A. pleuropneumoniae field strains and found that they secreted either ApxI, ApxII, ApxI and ApxII, or ApxII and ApxIII and secreted no other cytolytic activities. However, proteins similar to ApxI and ApxII were also produced by Actinobacillus suis. Images PMID:8063425

  12. Dynamic Recrystallization in Ice : In-Situ Observation of the Strain Field during Grain Nucleation.

    NASA Astrophysics Data System (ADS)

    Chauve, T.; Montagnat, M.; Tommasi, A.; Vacher, P.

    2014-12-01

    Dynamic recrystallization (DRX) occurs in minerals, metals, ice and impact on large scale mechanisms as seismic anisotropy, mechanical properties inside the Earth mantle, material forming and anisotropic flow in polar ice sheet, for instance. In this frame, ice can be considered as a model material due to a strong viscoplastic anisotropy and deformation heterogeneities, which are precursors of the recrystallization. During creep deformation at high temperature, DRX occurs from 1% strain and involves grain nucleation and grain boundary migration. As DRX induces an evolution of microstructure and texture, it strongly affects the mechanical behavior, and it is expected to modify the strain field at the grain and/or the sample scale. Creep test (σ=0.5-0.8 MPa) were performed at high temperature (T/Tf 0,98) on granular polycrystalline ice (grains size 1mm) and columnar polycrystalline ice (microstructure 2D 1/2 in plane grain size 10mm) up to 18 % strain. Columnar ice provides interesting feature as it contains only one grain through the thickness and the columns are parallel. Post-deformation texture analysis with an Automatic Ice Texture Analyzer (AITA) and with EBSD (Geoscience Montpellier) were used to investigate DRX impact on texture and microstructure, at different scales. With increasing strain texture evolves to a strong concentrated girdle with a preferential orientation of c-axis close to 35° from the compression axis. During the experiment, local strain field is measured on the surface of the sample by Digital Image Correlation (DIC) with a spatial resolution between 0.2 and 0.5 mm, and a strain resolution between 0.2% to 1%. Grain size being large, we obtain a relatively good intra-granular resolution of the strain field. Thanks to the 2D configuration of the columnar ice samples, we can superimpose the strain field measured by DIC. We will present an overview of the impact of DRX on the texture and microstructure, from the 3D configuration down to a

  13. Laboratory and field performance of FOS sensors in static and dynamic strain monitoring in concrete bridge decks

    NASA Astrophysics Data System (ADS)

    Benmokrane, B.; Debaiky, A.; El-Ragaby, A.; Roy, R.; El-Gamal, S.; El-Salakawy, E.

    2006-03-01

    There is a growing need for designing and constructing innovative concrete bridges using FRP reinforcing bars as internal reinforcement to avoid the corrosion problems and high costs of maintenance and repair. For efficient use and to increase the lifetime of these bridges, it is important to develop efficient monitoring systems for such innovative structures. Fabry-Perot and Bragg fibre optic sensors (FOS) that can measure the strains and temperature are promising candidates for life-long health monitoring of these structures. This article reports laboratory and field performance of Fabry-Perot and Bragg FOS sensors as well as electrical strain gauges in static and dynamic strain monitoring in concrete bridge decks. The laboratory tests include tensile testing of glass FRP bars and testing of full-scale concrete bridge deck slabs reinforced with glass and carbon FRP bars under static and cyclic concentrated loads. The field tests include static and dynamic testing of two bridges reinforced with steel and glass FRP bars. The obtained strain results showed satisfactory agreement between the different gauges.

  14. Different resistance patterns of reference and field strains of Brucella abortus

    PubMed Central

    Miranda, Karina L.; Dorneles, Elaine M. S.; Poester, Fernando P.; Martins, Paulo S.; Pauletti, Rebeca B.; Lage, Andrey P.

    2015-01-01

    The aim of this study was to evaluate the growth of the B. abortus reference strains and field isolates on media containing different inhibitor agents. Reference strains were seeded on tryptose agar containing: i-erythritol (1.0 mg/mL), fuchsin (20 μg/mL and 80 μg/mL), thionin (2.5 μg/mL and 10 μg/mL), rifampicin (200 μg/mL) and safranin O (200 μg/mL). Field isolates were tested only on media containing i-erythritol, rifampicin and thionin. Furthermore, each suspension was also inoculated on tryptose agar incubated in air, to test its ability to grow without CO 2 . Sensitivity to fuchsin was similar among reference strains evaluated. Growth of S19, 544 and 2308 but not RB51 were inhibited on media containing rifampicin. Medium with safranin O showed no inhibition for RB51, 544 and 2308, but it partially inhibited the S19 growth as well as medium containing i-erythritol. Treatment/control growth ratio for 2308 on tryptose agar containing thionin (2.5 μg/mL) was approximatelly 1.0, whereas S19 and RB51 showed 0.85 and 0.89 ratios, respectively. Growth of 544, S19 and RB51 but not 2308 was completely inhibited on medium with thionin (10 μg/mL). All field strains grew on medium containing i-erythritol, but were completelly inhibited by rifampicin. With exception of A1 ( B. abortus biovar 3) all field isolates grew on medium with thionin, although some strains showed a treatment/control growth ratio of 0.75–0.80 (10 μg/mL). These results showed that tryptose agar with thionin, i-erythritol or rifampicin could be useful for differentiating vaccine, challenge and field strains of B. abortus. PMID:26221116

  15. Different resistance patterns of reference and field strains of Brucella abortus.

    PubMed

    Miranda, Karina L; Dorneles, Elaine M S; Poester, Fernando P; Martins Filho, Paulo S; Pauletti, Rebeca B; Lage, Andrey P

    2015-03-01

    The aim of this study was to evaluate the growth of the B. abortus reference strains and field isolates on media containing different inhibitor agents. Reference strains were seeded on tryptose agar containing: i-erythritol (1.0 mg/mL), fuchsin (20 μg/mL and 80 μg/mL), thionin (2.5 μg/mL and 10 μg/mL), rifampicin (200 μg/mL) and safranin O (200 μg/mL). Field isolates were tested only on media containing i-erythritol, rifampicin and thionin. Furthermore, each suspension was also inoculated on tryptose agar incubated in air, to test its ability to grow without CO 2 . Sensitivity to fuchsin was similar among reference strains evaluated. Growth of S19, 544 and 2308 but not RB51 were inhibited on media containing rifampicin. Medium with safranin O showed no inhibition for RB51, 544 and 2308, but it partially inhibited the S19 growth as well as medium containing i-erythritol. Treatment/control growth ratio for 2308 on tryptose agar containing thionin (2.5 μg/mL) was approximatelly 1.0, whereas S19 and RB51 showed 0.85 and 0.89 ratios, respectively. Growth of 544, S19 and RB51 but not 2308 was completely inhibited on medium with thionin (10 μg/mL). All field strains grew on medium containing i-erythritol, but were completelly inhibited by rifampicin. With exception of A1 ( B. abortus biovar 3) all field isolates grew on medium with thionin, although some strains showed a treatment/control growth ratio of 0.75-0.80 (10 μg/mL). These results showed that tryptose agar with thionin, i-erythritol or rifampicin could be useful for differentiating vaccine, challenge and field strains of B. abortus.

  16. Second-Harmonic Generation scanning microscopy of strain fields around Through-Silicon-Vias

    NASA Astrophysics Data System (ADS)

    Cho, Yujin; Shafiei, Farbod; Mendoza, Bernardo; Jiang, Tengfei; Ho, Paul; Downer, Michael

    Through-Silicon-Vias (TSVs) improve electrical performance of integrated circuits and reduce power consumption by interconnecting vertically stacked silicon layers. Cu has been commonly used for TSVs because of its good electrical and mechanical properties. However, mismatch in thermal expansion coefficient of Si and Cu induces strain fields on the surfaces, which can degrade the performance of nearby devices and crack the surfaces. In this work, using non-invasive Second Harmonic Generation (SHG) microscopy, we successfully characterized inhomogeneous distribution of the thermally induced strain fields. High strain gradients strengthen SHG intensity, since it breaks centrosymmetry in Si. In p-polarized incoming beam and s-polarized SHG configuration, we were able to see the strain effect directly, while in p-in/ p-out polarization, strain-induced SHG was coupled with background SHG from Si. We will present SHG micrographs compared with Raman measurement and the theory of strain-induced SHG, as well as wavelength and power dependence of SHG

  17. Strain on field effect transistors with single–walled–carbon nanotube network on flexible substrate

    SciTech Connect

    Kim, T. G.; Kim, U. J.; Lee, E. H.; Hwang, J. S.; Hwang, S. W. E-mail: sangsig@korea.ac.kr; Kim, S. E-mail: sangsig@korea.ac.kr

    2013-12-07

    We have systematically analyzed the effect of strain on the electrical properties of flexible field effect transistors with a single-walled carbon nanotube (SWCNT) network on a polyethersulfone substrate. The strain was applied and estimated at the microscopic scale (<1 μm) by using scanning electron microscope (SEM) equipped with indigenously designed special bending jig. Interestingly, the strain estimated at the microscopic scale was found to be significantly different from the strain calculated at the macroscopic scale (centimeter-scale), by a factor of up to 4. Further in-depth analysis using SEM indicated that the significant difference in strain, obtained from two different measurement scales (microscale and macroscale), could be attributed to the formation of cracks and tears in the SWCNT network, or at the junction of SWCNT network and electrode during the strain process. Due to this irreversible morphological change, the electrical properties, such as on current level and field effect mobility, lowered by 14.3% and 4.6%, respectively.

  18. The in vitro response of field strains of sheep blowflies Lucilia sericata and L. cuprina (Calliphoridae) in New Zealand to dicyclanil and triflumuron.

    PubMed

    Waghorn, T S; McKay, C H; Heath, A Cg

    2013-09-01

    To evaluate the in vitro efficacy of triflumuron and dicyclanil against field strains of Lucilia sericata and L. cuprina in New Zealand to establish whether anecdotal reports of declining protection periods afforded by dips containing these active ingredients had validity. Strains of field-derived blowflies (Lucilia cuprina and L. sericata) were obtained from adult flies from flytraps or larvae from sheep with flystrike submitted from seven regions of the North and two regions of the South Islands of New Zealand. A total of 27 strains of L. sericata and 19 of L. cuprina were established in culture and first instar larvae obtained were exposed in vitro to dilution series of technical-grade dicyclanil (a pyrimidine carbonitrile) and triflumuron (a benzoyl urea). Concentrations lethal to 50% (LC50) and 95% (LC95) of each strain were calculated and tested by probit analysis, with the ratio of LC50 of each strain divided by LC50 of the most susceptible strain (resistance factor) derived in order to facilitate between-strain comparisons of susceptibility. There was considerable variation between strains of L. sericata larvae in their susceptibility to triflumuron, with those least susceptible originating from the Waikato region. Strains from both Tararua and Manawatu regions were most susceptible and East Coast strains intermediate. All strains of the species tested showed a narrow band of susceptibility to dicyclanil with no regional trends apparent. Representative field-strains of sheep blowflies exhibited a range of susceptibilities to both triflumuron and dicyclanil, suggestive of both genetic heterogeneity among fly populations and the spectrum of dip use in their source areas. This means there should be concerns for the long-term benefits of benzoyl urea insecticides for sheep farmers in New Zealand, but not yet for dicyclanil-based formulations. Flystrike is a debilitating and occasionally lethal disease in sheep such that efficacious sheep dips have prophylactic

  19. 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

  20. High resolution monitoring of strain fields in concrete during hydraulic fracturing processes.

    PubMed

    Chen, Rongzhang; Zaghloul, Mohamed A S; Yan, Aidong; Li, Shuo; Lu, Guanyi; Ames, Brandon C; Zolfaghari, Navid; Bunger, Andrew P; Li, Ming-Jun; Chen, Kevin P

    2016-02-22

    We present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this paper provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.

  1. High resolution monitoring of strain fields in concrete during hydraulic fracturing processes

    DOE PAGES

    Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong; ...

    2016-02-17

    Here, we present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this papermore » provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.« less

  2. Full-field strain measurements on turbomachinery components using 3D SLDV technology

    NASA Astrophysics Data System (ADS)

    Maguire, Martyn; Sever, Ibrahim

    2016-06-01

    This paper focuses on measurements of 3D Operating Deflection Shapes (ODSs), and subsequently, construction of full-field surface strain maps of a number of turbomachinery components. For this purpose a 3D Scanning Laser Doppler Vibrometer (SLDV) is used. The ODS measurements are performed for a large number of modes and results obtained are compared with the 1-D shapes that are most commonly measured. It is demonstrated that the 3D measurements are a significant improvement over the 1-D case in terms of independent amount of extra information they provide. This is confirmed through comparisons with FE results. Special tests are carried out to recover the full-field strain on scanned faces of the components used. Visual comparison of these measurements with FE counterparts reveal that strain maps can be successfully measured, not only for low frequency modes but also for highly complex high frequency ones. These maps are measured with different levels of input force to assess the linearity of strain results to varying response amplitudes. Lessons learnt and observations made are summarised in concluding remarks and the scope of future work to take this study into the production environment is discussed. This study constitutes a unique comprehensive investigation into full-field strain measurements using real application hardware and a large frequency range.

  3. High resolution monitoring of strain fields in concrete during hydraulic fracturing processes

    SciTech Connect

    Chen, Rongzhang; Zaghloul, Mohamed A. S.; Yan, Aidong; Li, Shuo; Lu, Guanyi; Ames, Brandon C.; Zolfaghari, Navid; Bunger, Andrew P.; Li, Ming -Jun; Chen, Kevin P.

    2016-02-17

    Here, we present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this paper provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.

  4. Computational study on electrical properties of transition metal dichalcogenide field-effect transistors with strained channel

    SciTech Connect

    Harada, Naoki; Sato, Shintaro; Yokoyama, Naoki

    2014-01-21

    The performance limits of monolayer transition metal dichalcogenide (TMDC) field-effect transistors (FETs) with isotropic biaxial strain were examined with the “top-of-the-barrier” ballistic MOSFET model. Using a first-principle theory, we calculated the band structures and density of states of strained monolayer MoS{sub 2} and WS{sub 2}, and used the results in model calculations. Introducing strain moves the positions of the conduction band minimum and valence band maximum in k-space with resultant variation in the effective mass and population of carriers. Introducing 2% tensile strain into n-type MoS{sub 2} FETs decreases the electron effective mass and, at the same time, increases energy separation between the lower and the higher valleys in the conduction band, resulting in 26% improvement of the ON current up to 1260 A/m. Whereas compressive strain results in complicated effects, −2% strain also improves the ON current by 15%. These results suggest that introducing artificial strain is promising to improve TMDC FET performance.

  5. Aflatoxigenic Aspergillus flavus and Aspergillus parasiticus strains in Hungarian maize fields.

    PubMed

    Sebők, Flóra; Dobolyi, Csaba; Zágoni, Dóra; Risa, Anita; Krifaton, Csilla; Hartman, Mátyás; Cserháti, Mátyás; Szoboszlay, Sándor; Kriszt, Balázs

    2016-12-01

    Due to the climate change, aflatoxigenic Aspergillus species and strains have appeared in several European countries, contaminating different agricultural commodities with aflatoxin. Our aim was to screen the presence of aflatoxigenic fungi in maize fields throughout the seven geographic regions of Hungary. Fungi belonging to Aspergillus section Flavi were isolated in the ratio of 26.9% and 42.3% from soil and maize samples in 2013, and these ratios decreased to 16.1% and 34.7% in 2014. Based on morphological characteristics and the sequence analysis of the partial calmodulin gene, all isolates proved to be Aspergillus flavus, except four strains, which were identified as Aspergillus parasiticus. About half of the A. flavus strains and all the A. parasiticus strains were able to synthesize aflatoxins. Aflatoxigenic Aspergillus strains were isolated from all the seven regions of Hungary. A. parasiticus strains were found in the soil of the regions Southern Great Plain and Southern Transdanubia and in a maize sample of the region Western Transdanubia. In spite of the fact that aflatoxins have rarely been detected in feeds and foods in Hungary, aflatoxigenic A. flavus and A. parasiticus strains are present in the maize culture throughout Hungary posing a potential threat to food safety.

  6. Trip Report-Produced-Water Field Testing

    SciTech Connect

    Sullivan, Enid J.

    2012-05-25

    Los Alamos National Laboratory (LANL) conducted field testing of a produced-water pretreatment apparatus with assistance from faculty at the Texas A&M University (TAMU) protein separation sciences laboratory located on the TAMU main campus. The following report details all of the logistics surrounding the testing. The purpose of the test was to use a new, commercially-available filter media housing containing modified zeolite (surfactant-modified zeolite or SMZ) porous medium for use in pretreatment of oil and gas produced water (PW) and frac-flowback waters. The SMZ was tested previously in October, 2010 in a lab-constructed configuration ('old multicolumn system'), and performed well for removal of benzene, toluene, ethylbenzene, and xylenes (BTEX) from PW. However, a less-expensive, modular configuration is needed for field use. A modular system will allow the field operator to add or subtract SMZ filters as needed to accommodate site specific conditions, and to swap out used filters easily in a multi-unit system. This test demonstrated the use of a commercial filter housing with a simple flow modification and packed with SMZ for removing BTEX from a PW source in College Station, Texas. The system will be tested in June 2012 at a field site in Pennsylvania for treating frac-flowback waters. The goals of this test are: (1) to determine sorption efficiency of BTEX in the new configuration; and (2) to observe the range of flow rates, backpressures, and total volume treated at a given flow rate.

  7. Strain field evolution during creep on ice. Impact of dynamic recrystallization mechanisms.

    NASA Astrophysics Data System (ADS)

    Chauve, Thomas; Montagnat, Maurine; Barou, Fabrice; Hidas, Karoly; Tommasi, Andréa; Vacher, Pierre

    2015-04-01

    Discontinuous Dynamic Recrystallization (DDRX) occurs in minerals, metals, ice and impacts on texture and microstructure evolution during deformation. It therefore impacts on large scale mechanisms as seismic anisotropy, mechanical properties inside the Earth mantle, material forming and anisotropic flow in polar ice sheet, for instance. In this frame, ice can be considered as a model material due to a strong viscoplastic anisotropy inducing strong deformation heterogeneities, that are precursors of recrystallization. During creep deformation at high temperature in the laboratory, DDRX occurs from 1% strain and involves grain nucleation and grain boundary migration. As DDRX induces an evolution of microstructure and texture, it strongly affects the mechanical behavior (1,2), and it is expected to modify the strain field at the grain and/or the sample scale. Compressive creep test (σ=0.5-0.8 MPa) were performed at high temperature (T/Tf 0,98) on granular polycrystalline ice (grains size 1mm) and columnar polycrystalline ice (microstructure 2D 1/2 in plane grain size 10mm) up to 18 % strain. Columnar ice provides interesting feature as it contains only one grain through the thickness and the columns are parallel. Post-deformation texture analyses with an Automatic Ice Texture Analyzer (AITA) and with EBSD (CrystalProbe MEB of Geoscience Montpellier) were used to investigate DDRX mechanisms at high resolution, and deduce their impact on texture and microstructure, at different scales. During the experiment, local strain field is measured on the surface of the sample by Digital Image Correlation (DIC) (3) with a spatial resolution between 0.2 and 0.5 mm, and a strain resolution between 0.2% to 1%. Grain size being large, we obtain a relatively good intra-granular resolution of the strain field. Thanks to the 2D configuration of the columnar ice samples, we can superimpose the initial microstructure to the strain field measured by DIC. We will present an overview of

  8. Application of the digital volume correlation technique for the measurement of displacement and strain fields in bone: a literature review.

    PubMed

    Roberts, Bryant C; Perilli, Egon; Reynolds, Karen J

    2014-03-21

    Digital volume correlation (DVC) provides experimental measurements of displacements and strains throughout the interior of porous materials such as trabecular bone. It can provide full-field continuum- and tissue-level measurements, desirable for validation of finite element models, by comparing image volumes from subsequent µCT scans of a sample in unloaded and loaded states. Since the first application of DVC for measurement of strain in bone tissue, subsequent reports of its application to trabecular bone cores up to whole bones have appeared within the literature. An "optimal" set of procedures capable of precise and accurate measurements of strain, however, still remains unclear, and a systematic review focussing explicitly on the increasing number of DVC algorithms applied to bone or structurally similar materials is currently unavailable. This review investigates the effects of individual parameters reported within individual studies, allowing to make recommendations for suggesting algorithms capable of achieving high accuracy and precision in displacement and strain measurements. These recommendations suggest use of subsets that are sufficiently large to encompass unique datasets (e.g. subsets of 500 µm edge length when applied to human trabecular bone cores, such as cores 10mm in height and 5mm in diameter, scanned at 15 µm voxel size), a shape function that uses full affine transformations (translation, rotation, normal strain and shear strain), the robust normalized cross-correlation coefficient objective function, and high-order interpolation schemes. As these employ computationally burdensome algorithms, researchers need to determine whether they have the necessary computational resources or time to adopt such strategies. As each algorithm is suitable for parallel programming however, the adoption of high precision techniques may become more prevalent in the future.

  9. Earth Strain Measurements with a Laser Interferometer: An 800-meter Michelson interferometer monitors the earth's strain field on the surface of the ground.

    PubMed

    Berger, J; Lovberg, R H

    1970-10-16

    The development of the laser as a source of coherent optical radiation has permitted the application of interferometric techniques to the problem of earth strain measurement. By use of this technology, an 800-meter laser strain meter has been developed which operates above the surface of the ground. The instrument has a strain least count of 10(-10), requires no calibration, and has a flat and linear response from zero frequency to 1 megahertz. The linearity and large dynamic range of the laser strain meter offer unprecedented versatility in the recording of seismic strains associated with earthquakes and nuclear blasts. The extremely wide bandwidth opens new areas of the strain spectrum to investigation. A key to the understanding of the state of stress of the earth and the association phenomona of tectonic activity and earthquakes is a knowledge of the spatial distribution of the earth strain. Measurements of secular strain and earth tides indicate that, even at these long periods, surface strain measurements are valid representations of earth strain at depth. The LSM thus provides a means of making crustal strain measurements at points selected for maximum geophysical interest and ultimately allow the mapping of strain field distributions.

  10. Note: Dynamic strain field mapping with synchrotron X-ray digital image correlation

    SciTech Connect

    Lu, L.; Fan, D.; Luo, S. N.; Bie, B. X.; Ran, X. X.; Qi, M. L.; Parab, N.; Sun, J. Z.; Liao, H. J.; Hudspeth, M. C.; Claus, B.; Fezzaa, K.; Sun, T.; Chen, W.; Gong, X. L.

    2014-07-15

    We present a dynamic strain field mapping method based on synchrotron X-ray digital image correlation (XDIC). Synchrotron X-ray sources are advantageous for imaging with exceptional spatial and temporal resolutions, and X-ray speckles can be produced either from surface roughness or internal inhomogeneities. Combining speckled X-ray imaging with DIC allows one to map strain fields with high resolutions. Based on experiments on void growth in Al and deformation of a granular material during Kolsky bar/gas gun loading at the Advanced Photon Source beamline 32ID, we demonstrate the feasibility of dynamic XDIC. XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation.

  11. Strain measurement in ferromagnetic crystals using dark-field electron holography

    NASA Astrophysics Data System (ADS)

    Murakami, Yasukazu; Niitsu, Kodai; Kaneko, Syuhei; Tanigaki, Toshiaki; Sasaki, Taisuke; Akase, Zentaro; Shindo, Daisuke; Ohkubo, Tadakatsu; Hono, Kazuhiro

    2016-11-01

    This study proposes a method to separate the geometric phase shift due to lattice strain from the undesired phase information, resulting from magnetic fields that are superposed in the dark-field electron holography (DFEH) observations. Choosing a distinct wave vector for the Bragg reflection reversed the sense of the geometric phase shift, while the sense of the magnetic information remained unchanged. In the case of an Nd-Fe-B permanent magnet, once the unwanted signal was removed by data processing, the residual phase image revealed a strain map. Even though the applications of DFEH have thus far been limited to non-magnetic systems, the method proposed in this work is also applicable to strain measurements in various ferromagnetic systems.

  12. Giant electric-field-induced strain in lead-free piezoelectric materials

    PubMed Central

    Chen, Lan; Yang, Yurong; Meng, X. K.

    2016-01-01

    First-principles calculations are performed to investigate the structures, electrical, and magnetic properties of compressive BiFeO3 films under electric-field and pressure perpendicular to the films. A reversible electric-field-induced strain up 10% is achieved in the compressive BiFeO3 films. The giant strain originates from rhombohedral-tetragonal (R-T) phase transition under electric-filed, and is recoverable from tetragonal-rhombohedral (T-R) phase transition by compressive stress. Additionally, the weak ferromagnetism in BiFeO3 films is largely changed in R-T phase transition under electric-filed and T-R phase transition under pressure – reminiscent of magnetoelectric effect and magnetoelastic effect. These results suggest exciting device opportunities arising from the giant filed-induced strain, large magnetoelectric effect and magnetoelastic effect. PMID:27139526

  13. Strain fields induced by kink band propagation in Cu-Nb nanolaminate composites

    DOE PAGES

    Nizolek, T. J.; Begley, M. R.; McCabe, R. J.; ...

    2017-07-01

    Kink band formation is a common deformation mode for anisotropic materials and has been observed in polymer matrix fiber composites, single crystals, geological formations, and recently in metallic nanolaminates. While numerous studies have been devoted to kink band formation, the majority do not consider the often rapid and unstable process of kink band propagation. In this paper, we take advantage of stable kink band formation in Cu-Nb nanolaminates to quantitatively map the local strain fields surrounding a propagating kink band during uniaxial compression. Kink bands are observed to initiate at specimen edges, propagate across the sample during a rising globalmore » stress, and induce extended strain fields in the non-kinked material surrounding the propagating kink band. Finally, it is proposed that these stress/strain fields significantly contribute to the total energy dissipated during kinking and, analogous to crack tip stress/strain fields, influence the direction of kink propagation and therefore the kink band inclination angle.« less

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

    NASA Astrophysics Data System (ADS)

    Levy, Niv

    2011-03-01

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

  15. Effect of Agave tequilana age, cultivation field location and yeast strain on tequila fermentation process.

    PubMed

    Pinal, L; Cornejo, E; Arellano, M; Herrera, E; Nuñez, L; Arrizon, J; Gschaedler, A

    2009-05-01

    The effect of yeast strain, the agave age and the cultivation field location of agave were evaluated using kinetic parameters and volatile compound production in the tequila fermentation process. Fermentations were carried out with Agave juice obtained from two cultivation fields (CF1 and CF2), as well as two ages (4 and 8 years) and two Saccharomyces cerevisiae yeast strains (GU3 and AR5) isolated from tequila fermentation must. Sugar consumption and ethanol production varied as a function of cultivation field and agave age. The production of ethyl acetate, 1-propanol, isobutanol and amyl alcohols were influenced in varying degrees by yeast strain, agave age and cultivation field. Methanol production was only affected by the agave age and 2-phenylethanol was influenced only by yeast strain. This work showed that the use of younger Agave tequilana for tequila fermentation resulted in differences in sugar consumption, ethanol and volatile compounds production at the end of fermentation, which could affect the sensory quality of the final product.

  16. Surface strain-field determination of tympanic membrane using 3D-digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Hernandez-Montes, María del S.; Mendoza Santoyo, Fernando; Muñoz, Silvino; Perez, Carlos; de la Torre, Manuel; Flores, Mauricio; Alvarez, Luis

    2015-08-01

    In order to increase the understanding of soft tissues mechanical properties, 3D Digital Holographic Interferometry (3D-DHI) was used to quantify the strain-field on a cat tympanic membrane (TM) surface. The experiments were carried out applying a constant sound-stimuli pressure of 90 dB SPL (0.632 Pa) on the TM at 1.2 kHz. The technique allows the accurate acquisition of the micro-displacement data along the x, y and z directions, which is a must for a full characterization of the tissue mechanical behavior under load, and for the calculation of the strain-field in situ. The displacements repeatability in z direction shows a standard deviation of 0.062 μm at 95% confidence level. In order to realize the full 3D characterization correctly the contour of the TM surface was measured employing the optically non-contact two-illumination positions contouring method. The x, y and z displacements combined with the TM contour data allow the evaluation its strain-field by spatially differentiating the u(m,n), v(m,n), and w(m,n) deformation components. The accurate and correct determination of the TM strain-field leads to describing its elasticity, which is an important parameter needed to improve ear biomechanics studies, audition processes and TM mobility in both experimental measurements and theoretical analysis of ear functionality and its modeling.

  17. Simulation-based design of a strained graphene field effect transistor incorporating the pseudo magnetic field effect

    SciTech Connect

    Souma, Satofumi Ueyama, Masayuki; Ogawa, Matsuto

    2014-05-26

    We present a numerical study on the performance of strained graphene-based field-effect transistors. A local strain less than 10% is applied over a central channel region of the graphene to induce the shift of the Dirac point in the channel region along the transverse momentum direction. The left and the right unstrained graphene regions are doped to be either n-type or p-type. By using the atomistic tight-binding model and a Green's function method, we predict that the gate voltage applied to the central strained graphene region can switch the drain current on and off with an on/off ratio of more than six orders of magnitude at room temperature. This is in spite of the absence of a bandgap in the strained channel region. Steeper subthreshold slopes below 60 mV/decade are also predicted at room temperature because of a mechanism similar to the band-to-band tunneling field-effect transistors.

  18. Simulation-based design of a strained graphene field effect transistor incorporating the pseudo magnetic field effect

    NASA Astrophysics Data System (ADS)

    Souma, Satofumi; Ueyama, Masayuki; Ogawa, Matsuto

    2014-05-01

    We present a numerical study on the performance of strained graphene-based field-effect transistors. A local strain less than 10% is applied over a central channel region of the graphene to induce the shift of the Dirac point in the channel region along the transverse momentum direction. The left and the right unstrained graphene regions are doped to be either n-type or p-type. By using the atomistic tight-binding model and a Green's function method, we predict that the gate voltage applied to the central strained graphene region can switch the drain current on and off with an on/off ratio of more than six orders of magnitude at room temperature. This is in spite of the absence of a bandgap in the strained channel region. Steeper subthreshold slopes below 60 mV/decade are also predicted at room temperature because of a mechanism similar to the band-to-band tunneling field-effect transistors.

  19. Construction of bioluminescent cyanobacterial reporter strains for detection of nickel, cobalt and zinc.

    PubMed

    Peca, Loredana; Kós, Péter B; Máté, Zoltan; Farsang, Andrea; Vass, Imre

    2008-12-01

    Two whole-cell bioluminescent reporters were constructed by fusing the reporter genes luxAB with the Co(2+) and Zn(2+) inducible coaT promoter or the Ni(2+)-inducible nrsBACD promoter, respectively, in the genome of Synechocystis sp. PCC 6803. The obtained reporters, designated coaLux and nrsLux, respectively, responded quantitatively to metal ions. After 3 h incubation at 40 micromol m(-2) s(-1) visible light, the detection range of coaLux was 0.3-6 microM for Co(2+) and 1-3 microM for Zn(2+). Incubation in darkness increased the detection range by about four times. The nrsLux reporter was specific to Ni(2+), with a detection range of 0.2-6 microM. However, its activity was inhibited by Zn(2+) with a half maximal inhibitory concentration c. 6 microM, and totally inhibited by darkness. This is the first whole-cell Ni(2+)-specific reporter with a clear dose-signal relationship. In a soil-like mixture of different chemical and oil industry wastes, the coaLux reporter strain detected about 90% of the zinc content of the sample. This study demonstrates the potential for development of a rapid, simple and economical field assay for nickel, cobalt and zinc detection using the coaLux and nrsLux reporters.

  20. Broad-range lytic bacteriophages that kill Staphylococcus aureus local field strains.

    PubMed

    Abatángelo, Virginia; Peressutti Bacci, Natalia; Boncompain, Carina A; Amadio, Ariel A; Carrasco, Soledad; Suárez, Cristian A; Morbidoni, Héctor R

    2017-01-01

    Staphylococcus aureus is a very successful opportunistic pathogen capable of causing a variety of diseases ranging from mild skin infections to life-threatening sepsis, meningitis and pneumonia. Its ability to display numerous virulence mechanisms matches its skill to display resistance to several antibiotics, including β-lactams, underscoring the fact that new anti-S. aureus drugs are urgently required. In this scenario, the utilization of lytic bacteriophages that kill bacteria in a genus -or even species- specific way, has become an attractive field of study. In this report, we describe the isolation, characterization and sequencing of phages capable of killing S. aureus including methicillin resistant (MRSA) and multi-drug resistant S. aureus local strains from environmental, animal and human origin. Genome sequencing and bio-informatics analysis showed the absence of genes encoding virulence factors, toxins or antibiotic resistance determinants. Of note, there was a high similarity between our set of phages to others described in the literature such as phage K. Considering that reported phages were obtained in different continents, it seems plausible that there is a commonality of genetic features that are needed for optimum, broad host range anti-staphylococcal activity of these related phages. Importantly, the high activity and broad host range of one of our phages underscores its promising value to control the presence of S. aureus in fomites, industry and hospital environments and eventually on animal and human skin. The development of a cocktail of the reported lytic phages active against S. aureus-currently under way- is thus, a sensible strategy against this pathogen.

  1. Broad-range lytic bacteriophages that kill Staphylococcus aureus local field strains

    PubMed Central

    Boncompain, Carina A.; Amadio, Ariel A.; Carrasco, Soledad; Suárez, Cristian A.

    2017-01-01

    Staphylococcus aureus is a very successful opportunistic pathogen capable of causing a variety of diseases ranging from mild skin infections to life-threatening sepsis, meningitis and pneumonia. Its ability to display numerous virulence mechanisms matches its skill to display resistance to several antibiotics, including β-lactams, underscoring the fact that new anti-S. aureus drugs are urgently required. In this scenario, the utilization of lytic bacteriophages that kill bacteria in a genus -or even species- specific way, has become an attractive field of study. In this report, we describe the isolation, characterization and sequencing of phages capable of killing S. aureus including methicillin resistant (MRSA) and multi-drug resistant S. aureus local strains from environmental, animal and human origin. Genome sequencing and bio-informatics analysis showed the absence of genes encoding virulence factors, toxins or antibiotic resistance determinants. Of note, there was a high similarity between our set of phages to others described in the literature such as phage K. Considering that reported phages were obtained in different continents, it seems plausible that there is a commonality of genetic features that are needed for optimum, broad host range anti-staphylococcal activity of these related phages. Importantly, the high activity and broad host range of one of our phages underscores its promising value to control the presence of S. aureus in fomites, industry and hospital environments and eventually on animal and human skin. The development of a cocktail of the reported lytic phages active against S. aureus–currently under way- is thus, a sensible strategy against this pathogen. PMID:28742812

  2. Deep Borehole Field Test Conceptual Design Report

    SciTech Connect

    Hardin, Ernest L.

    2016-09-30

    This report documents conceptual design development for the Deep Borehole Field Test (DBFT), including test packages (simulated waste packages, not containing waste) and a system for demonstrating emplacement and retrieval of those packages in the planned Field Test Borehole (FTB). For the DBFT to have demonstration value, it must be based on conceptualization of a deep borehole disposal (DBD) system. This document therefore identifies key options for a DBD system, describes an updated reference DBD concept, and derives a recommended concept for the DBFT demonstration. The objective of the DBFT is to confirm the safety and feasibility of the DBD concept for long-term isolation of radioactive waste. The conceptual design described in this report will demonstrate equipment and operations for safe waste handling and downhole emplacement of test packages, while contributing to an evaluation of the overall safety and practicality of the DBD concept. The DBFT also includes drilling and downhole characterization investigations that are described elsewhere (see Section 1). Importantly, no radioactive waste will be used in the DBFT, nor will the DBFT site be used for disposal of any type of waste. The foremost performance objective for conduct of the DBFT is to demonstrate safe operations in all aspects of the test.

  3. Genotypic diversity in Babesia bovis field isolates and vaccine strains from South Africa.

    PubMed

    Combrink, M P; Troskie, P C; Pienaar, R; Latif, A A; Mans, B J

    2014-01-31

    Genotypic diversity in Babesia bovis (cause of Asiatic redwater in cattle) vaccine strains and field isolates from South Africa were investigated using the Bv80 gene as well as microsatellites. The S11 vaccine strain possessed both A and B alleles of the Bv80 gene, as well as genotypic diversity within each allele type as defined by repeat variation resulting in different amplicon sizes. Rapid serial passage of vaccine strain from passage S10 to S24 resulted in loss of genotypic diversity that yielded a single allele A genotype with an amplicon size of 558 bp. This suggested that clonal selection occurred during rapid passaging. Extensive genotypic diversity exists in 44 field isolates characterized with both Bv80 A and B alleles, but can be readily distinguished from the S24 vaccine strain using either the Bv80 allele specific PCR assays or using multi-locus micro-satellite typing. This indicated that no recent documented clinical cases of Asiatic redwater were caused by the reversion to virulence of the current vaccine strain.

  4. Correlation between clinico-pathological outcome and typing of Haemophilus parasuis field strains.

    PubMed

    Aragon, Virginia; Cerdà-Cuéllar, Marta; Fraile, Lorenzo; Mombarg, Mark; Nofrarías, Miquel; Olvera, Alexandre; Sibila, Marina; Solanes, David; Segalés, Joaquim

    2010-05-19

    Haemophilus parasuis is the etiologic agent of Glässer's disease in pigs, which is pathologically characterized by serofibrinous polyserositis and arthritis. H. parasuis include virulent and non-virulent strains and confirmation of virulence in H. parasuis is still dependent on experimental reproduction of the disease. Since the variability in virulence is supported by serotyping and genotyping (particularly, multilocus sequence typing [MLST]), we examined the relationship between the classification of 8 field strains by these methods and their capacity to cause disease in snatch-farrowed, colostrum-deprived piglets. The severity of clinical signs and lesions produced by the different strains correlated with the quantity of H. parasuis recovered from the lesions. However, the virulence of the strains in the animal model did not show a total correlation with their serovar or their classification by MLST. More studies are needed to identify a virulence marker that could substitute animal experimentation in H. parasuis. In addition, we reproduced disease in domestic pigs with a strain isolated from the nasal cavity of wild boars. This result indicates the existence of virulent strains of H. parasuis in wild suids, which could produce disease under appropriate circumstances, and suggests a possible source of infection for domestic pigs. Copyright 2009 Elsevier B.V. All rights reserved.

  5. Direct observation of nanometer-scale strain field around CoSi{sub 2}/Si interface using scanning moiré fringe imaging

    SciTech Connect

    Kim, Suhyun; Jung, Younheum; Jung Kim, Joong; Byun, Gwangseon; Lee, Sunyoung; Lee, Heabum

    2014-04-21

    We report the use of scanning moiré fringe (SMF) imaging through high-angle annular dark-field scanning transmission electron microscopy (STEM) to measure the strain field around a CoSi{sub 2} contact embedded in the source and drain (S/D) region of a transistor. The atomic arrangement of the CoSi{sub 2}/Si (111) interface was determined from the high-resolution (HR)-STEM images, and the strain field formed around the S/D region was revealed by nanometer-scale SMFs appearing in the STEM image. In addition, we showed that the strain field in the S/D region measured by SMF imaging agreed with results obtained via peak-pairs analysis of HR-STEM images.

  6. Simultaneous 3D Strain and Flow Fields Measurement of a Model Artery under Unsteady Flows

    NASA Astrophysics Data System (ADS)

    Toloui, Mostafa; Sheng, Jian

    2011-11-01

    Fluid-Structure Interaction imposes challenges in both aero-elasticity and biomedical studies. A simultaneous solid deformation and fluid flow measurement technique based on digital in-line holographic particle tracking velocimetry (PTV) has been developed. It allows us to measure concurrently 3D strain field of a deforming structure and the unsteady flow near it. To facilitate the measurement, both wall and flow are seeded with tracer particles distinguished by size. The motion of these tracers provides the 3D deformation of the wall and the 3D velocity distribution of the flow separately. A fully index matched facility including transparent artery and NaI solution is constructed to enable observations near the wall or through the complex geometry. An arterial model with the inner diameter of 9.5 mm and the thickness of 0.9 mm is manufactured from the cross-linked transparent PDMS at the mixing ratio of 1:10 and doped with mono-dispersed 19 μm polystyrene particles. A cinematic holographic PTV system is used to trace the 3D particle motion in the model and flow simultaneously. Preliminary study is performed within a sample volume of 15 × 15 × 75 mm with the spatial resolution of 7.4 μm in lateral and 10 μm in depth. Uncertainty and accuracy analysis will be reported. NSF Grant No: CBET-0844647.

  7. Strain-Induced Gauge Field and Landau Levels in Acoustic Structures

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoju; Gao, Fei; Yang, Yahui; Zhang, Baile

    2017-05-01

    The emerging field of topological acoustics that explores novel gauge-field-related phenomena for sound has drawn attention in recent years. However, previous approaches constructing a synthetic gauge field for sound predominantly relied on a periodic system, being unable to form a uniform effective magnetic field, thus lacking access to some typical magnetic-induced quantum phenomena such as Landau energy quantization. Here we introduce strain engineering, previously developed in graphene electronics and later transferred to photonics, into a two-dimensional acoustic structure in order to form a uniform effective magnetic field for airborne acoustic wave propagation. Landau levels in the energy spectrum can be formed near the Dirac cone region. We also propose an experimentally feasible scheme to verify the existence of acoustic Landau levels with an acoustic measurement. As a new freedom of constructing a synthetic gauge field for sound, our study offers a path to previously inaccessible magneticlike effects in traditional periodic acoustic structures.

  8. Strain and stress fields in the Southern Apennines (Italy) constrained by geodetic, seismological and borehole data

    NASA Astrophysics Data System (ADS)

    Palano, M.; Cannavò, F.; Ferranti, L.; Mattia, M.; Mazzella, M. E.

    2011-12-01

    We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated comparison between the accrued strain recorded by geodetic data, and the strain released by seismic activity in a region hit by destructive historical earthquakes. To this end, we have used nine years of GPS observations (2001-2010) from a dense network of permanent stations, a data set of 73 well-constrained stress indicators (borehole breakouts and focal mechanisms of moderate-to-large earthquakes) and published estimations of the geological strain accommodated by active faults in the region. Although geodetic data are generally consistent with seismic and geological information, previously unknown features of the current deformation in southern Italy emerge from this analysis. The newly obtained GPS velocity field supports the well-established notion of a dominant NE-SW-oriented extension concentrated in a ˜50-km-wide belt along the topographic relief of the Apennines, as outlined by the distribution of seismogenic normal faults. Geodetic deformation is, however, non-uniform along the belt, with two patches of higher strain-rate and shear-stress accumulation in the north (Matese Mountains) and in the south (Irpinia area). Low geodetic strain-rates are found in the Bradano basin and Apulia plateau to the east. Along the Ionian Sea margin of southern Italy, in southern Apulia and eastern Basilicata and Calabria, geodetic velocities indicate NW-SE extension that is consistent with active shallow-crustal gravitational motion documented by geological studies. In the west, along the Tyrrhenian margin of the Campania region, the tectonic geodetic field is disturbed by volcanic processes. Comparison between the magnitude of the geodetic and the seismic strain rates (computed using a long historical seismicity catalogue) allow detecting

  9. Tuning the energy gap of bilayer α-graphyne by applying strain and electric field

    NASA Astrophysics Data System (ADS)

    Yang, Hang; Wu, Wen-Zhi; Jin, Yu; Wan-Lin, Guo

    2016-02-01

    Our density functional theory calculations show that the energy gap of bilayer α-graphyne can be modulated by a vertically applied electric field and interlayer strain. Like bilayer graphene, the bilayer α-graphyne has electronic properties that are hardly changed under purely mechanical strain, while an external electric field can open the gap up to 120 meV. It is of special interest that compressive strain can further enlarge the field induced gap up to 160 meV, while tensile strain reduces the gap. We attribute the gap variation to the novel interlayer charge redistribution between bilayer α-graphynes. These findings shed light on the modulation of Dirac cone structures and potential applications of graphyne in mechanical-electric devices. Project supported by the National Key Basic Research Program of China (Grant Nos. 2013CB932604 and 2012CB933403), the National Natural Science Foundation of China (Grant Nos. 51472117 and 51535005), the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures, China (Grant No. 0414K01), the Nanjing University of Aeronautics and Astronautics (NUAA) Fundamental Research Funds, China (Grant No. NP2015203), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

  10. Phenotypic and molecular characterization of native Azospirillum strains from rice fields to improve crop productivity.

    PubMed

    Sahoo, Ranjan K; Ansari, Mohammad W; Pradhan, Madhusmita; Dangar, Tushar K; Mohanty, Santanu; Tuteja, Narendra

    2014-07-01

    Beneficial microorganisms have been considered as an important tool for crop improvement. Native isolates of Azospirillum spp. were obtained from the rhizospheres of different rice fields. Phenotypic, biochemical and molecular characterizations of these isolates led to the identification of six efficient strain of Azospirillum. PCR amplification of the nif genes (nifH, nifD and nifK) and protein profile of Azospirillum strains revealed inter-generic and inter-specific diversity among the strains. In vitro nitrogen fixation performance and the plant growth promotion activities, viz. siderophore, HCN, salicylic acid, IAA, GA, zeatin, ABA, NH3, phosphorus metabolism, ACC deaminase and iron tolerance were found to vary among the Azospirillum strains. The effect of Azospirillum formulations on growth of rice var. Khandagiri under field condition was evaluated, which revealed that the native formulation of Azospirillum of CRRI field (As6) was most effective to elevate endogenous nutrient content, and improved growth and better yield are the result. The 16S rRNA sequence revealed novelty of native Azospirillum lipoferum (As6) (JQ796078) in the NCBI database.

  11. 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.

  12. Mapping Three-Dimensional Stress and Strain Fields within a Soft Hydrogel Using a Fluorescence Microscope

    PubMed Central

    Hall, Matthew S.; Long, Rong; Hui, Chung-Yuen; Wu, Mingming

    2012-01-01

    Three-dimensional cell culture is becoming mainstream as it is recognized that many animal cell types require the biophysical and biochemical cues within the extracellular matrices to perform truly physiologically realistic functions. However, tools for characterizing cellular mechanical environment are largely limited to cell culture plated on a two-dimensional substrate. We present a three-dimensional traction microscopy that is capable of mapping three-dimensional stress and strain within a soft and transparent extracellular matrix using a fluorescence microscope and a simple forward data analysis algorithm. We validated this technique by mapping the strain and stress field within the bulk of a thin polyacrylamide gel layer indented by a millimeter-size glass ball, together with a finite-element analysis. The experimentally measured stress and strain fields are in excellent agreements with results of the finite-element simulation. The unique contributions of the presented three-dimensional traction microscopy technique are: 1), the use of a fluorescence microscope in contrast with the confocal microscope that is required for the current three-dimensional traction microscopes in the literature; 2), the determination of the pressure field of an incompressible gel from strains; and 3), the simple forward-data-analysis algorithm. Future application of this technique for mapping animal cell traction in three-dimensional nonlinear biological gels is discussed. PMID:22677377

  13. MoS2/MX2 heterobilayers: bandgap engineering via tensile strain or external electrical field

    NASA Astrophysics Data System (ADS)

    Lu, Ning; Guo, Hongyan; Li, Lei; Dai, Jun; Wang, Lu; Mei, Wai-Ning; Wu, Xiaojun; Zeng, Xiao Cheng

    2014-02-01

    We have performed a comprehensive first-principles study of the electronic and magnetic properties of two-dimensional (2D) transition-metal dichalcogenide (TMD) heterobilayers MX2/MoS2 (M = Mo, Cr, W, Fe, V; X = S, Se). For M = Mo, Cr, W; X = S, Se, all heterobilayers show semiconducting characteristics with an indirect bandgap with the exception of the WSe2/MoS2 heterobilayer which retains the direct-bandgap character of the constituent monolayer. For M = Fe, V; X = S, Se, the MX2/MoS2 heterobilayers exhibit metallic characters. Particular attention of this study has been focused on engineering the bandgap of the TMD heterobilayer materials via application of either a tensile strain or an external electric field. We find that with increasing either the biaxial or uniaxial tensile strain, the MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can undergo a semiconductor-to-metal transition. For the WSe2/MoS2 heterobilayer, a direct-to-indirect bandgap transition may occur beyond a critical biaxial or uniaxial strain. For M (=Fe, V) and X (=S, Se), the magnetic moments of both metal and chalcogen atoms are enhanced when the MX2/MoS2 heterobilayers are under a biaxial tensile strain. Moreover, the bandgap of MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can be reduced by the vertical electric field. For two heterobilayers MSe2/MoS2 (M = Mo, Cr), PBE calculations suggest that the indirect-to-direct bandgap transition may occur under an external electric field. The transition is attributed to the enhanced spontaneous polarization. The tunable bandgaps in general and possible indirect-direct bandgap transitions due to tensile strain or external electric field make the TMD heterobilayer materials a viable candidate for optoelectronic applications.We have performed a comprehensive first-principles study of the electronic and magnetic properties of two-dimensional (2D) transition-metal dichalcogenide (TMD) heterobilayers MX2/MoS2 (M = Mo, Cr, W, Fe, V; X = S, Se). For

  14. Demonstration test of burner liner strain measuring system. Final Report

    SciTech Connect

    Stetson, K.A.

    1984-06-01

    A demonstration test was conducted for two systems of static strain measurement that had been shown to have potential for application jet engine combustors. A modified JT12D combustor was operated in a jet burner test stand while subjected simultaneously to both systems of instrumentation, i.e., Kanthal A-1 wire strain gages and laser speckle photography. A section of the burner was removed for installation and calibration of the wire gages, and welded back into the burner. The burner test rig was modified to provide a viewing port for the laser speckle photography such that the instrumented section could be observed during operation. Six out of ten wire gages survived testing and showed excellent repeatability. The extensive precalibration procedures were shown to be effective in compensating for the large apparent strains associated with these gages. Although all portions of the speckle photography system operated satisfactorily, a problem was encountered in the form of optical inhomogeneities in the hot, high-pressure gas flowing by the combustor case which generate large and random apparent strain distributions.

  15. Exploring the Diversity of Field Strains of Brucella abortus Biovar 3 Isolated in West Africa

    PubMed Central

    Sanogo, Moussa; Fretin, David; Thys, Eric; Saegerman, Claude

    2017-01-01

    Brucellosis is one of the most widespread bacterial zoonotic diseases in the world, affecting both humans and domestic and wild animals. Identification and biotyping of field strains of Brucella are of key importance for a better knowledge of the epidemiology of brucellosis, for identifying appropriate antigens, for managing disease outbreaks and for setting up efficient preventive and control programmes. Such data are required both at national and regional level to assess potential threats for public health. Highly discriminative genotyping methods such as the multiple locus variable number of tandem repeats analysis (MLVA) allow the comparison and assessment of genetic relatedness between field strains of Brucella within the same geographical area. In this study, MLVA biotyping data retrieved from the literature using a systematic review were compared using a clustering analysis and the Hunter-Gaston diversity index (HGDI). Thus, the analysis of the 42 MLVA genotyping results found in the literature on West Africa [i.e., from Ivory Coast (1), Niger (1), Nigeria (34), The Gambia (3), and Togo (3)] did not allow a complete assessment of the actual diversity among field strains of Brucella. However, it provided some preliminary indications on the co-existence of 25 distinct genotypes of Brucella abortus biovar 3 in this region with 19 genotypes from Nigeria, three from Togo and one from Ivory Coast, The Gambia, and Niger. The strong and urgent need for more sustainable molecular data on prevailing strains of Brucella in this sub-region of Africa and also on all susceptible species including humans is therefore highlighted. This remains a necessary stage to allow a comprehensive understanding of the relatedness between field strains of Brucella and the epidemiology of brucellosis within West Africa countries. PMID:28713359

  16. MoS2/MX2 heterobilayers: bandgap engineering via tensile strain or external electrical field.

    PubMed

    Lu, Ning; Guo, Hongyan; Li, Lei; Dai, Jun; Wang, Lu; Mei, Wai-Ning; Wu, Xiaojun; Zeng, Xiao Cheng

    2014-03-07

    We have performed a comprehensive first-principles study of the electronic and magnetic properties of two-dimensional (2D) transition-metal dichalcogenide (TMD) heterobilayers MX2/MoS2 (M = Mo, Cr, W, Fe, V; X = S, Se). For M = Mo, Cr, W; X = S, Se, all heterobilayers show semiconducting characteristics with an indirect bandgap with the exception of the WSe2/MoS2 heterobilayer which retains the direct-bandgap character of the constituent monolayer. For M = Fe, V; X = S, Se, the MX2/MoS2 heterobilayers exhibit metallic characters. Particular attention of this study has been focused on engineering the bandgap of the TMD heterobilayer materials via application of either a tensile strain or an external electric field. We find that with increasing either the biaxial or uniaxial tensile strain, the MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can undergo a semiconductor-to-metal transition. For the WSe2/MoS2 heterobilayer, a direct-to-indirect bandgap transition may occur beyond a critical biaxial or uniaxial strain. For M (=Fe, V) and X (=S, Se), the magnetic moments of both metal and chalcogen atoms are enhanced when the MX2/MoS2 heterobilayers are under a biaxial tensile strain. Moreover, the bandgap of MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can be reduced by the vertical electric field. For two heterobilayers MSe2/MoS2 (M = Mo, Cr), PBE calculations suggest that the indirect-to-direct bandgap transition may occur under an external electric field. The transition is attributed to the enhanced spontaneous polarization. The tunable bandgaps in general and possible indirect-direct bandgap transitions due to tensile strain or external electric field make the TMD heterobilayer materials a viable candidate for optoelectronic applications.

  17. Characterization of Genomic Island 3 and Genetic Variability of Chilean Field Strains of Brucella abortus▿

    PubMed Central

    Céspedes, Sandra; Salgado, Paulina; Valenzuela, Patricio; Vidal, Roberto; Oñate, Angel A.

    2011-01-01

    One of the capabilities developed by bacteria is the ability to gain large fragments of DNA from other bacteria or to lose portions of their own genomes. Among these exchangeable fragments are the genomic islands (GIs). Nine GIs have been identified in Brucella, and genomic island 3 (GI-3) is shared by two pathogenic species, B. melitensis and B. abortus. GI-3 encodes mostly unknown proteins. One of the aims of this study was to perform pulsed-field gel electrophoresis (PFGE) on field isolates of B. abortus from Chile to determine whether these isolates are clonally related. Furthermore, we focused on the characterization of GI-3, studying its organization and the genetic conservation of the GI-3 sequence using techniques such as tiling-path PCR (TP-PCR) and restriction fragment length polymorphism-PCR (RFLP-PCR). Our results, after PFGE was performed on 69 field isolates of B. abortus from Chile, showed that the strains were genetically homogeneous. To increase the power of genetic discrimination among these strains, we used multiple locus variable-number tandem-repeat (VNTR) analysis with 16 loci (MLVA-16). The results obtained by MLVA-16 showed that the strains of B. abortus were genetically heterogeneous and that most of them clustered according to their geographic origin. Of the genetic loci studied, panel 2B was the one describing the highest diversity in the analysis, as well as locus Bruce19 in panel 2A. In relation to the study of GI-3, our experimental analysis by TP-PCR identified and confirmed that GI-3 is present in all wild strains of B. abortus, demonstrating the high stability of gene cluster GI-3 in Chilean field strains. PMID:21543580

  18. Characterization of genomic island 3 and genetic variability of Chilean field strains of Brucella abortus.

    PubMed

    Céspedes, Sandra; Salgado, Paulina; Valenzuela, Patricio; Vidal, Roberto; Oñate, Angel A

    2011-07-01

    One of the capabilities developed by bacteria is the ability to gain large fragments of DNA from other bacteria or to lose portions of their own genomes. Among these exchangeable fragments are the genomic islands (GIs). Nine GIs have been identified in Brucella, and genomic island 3 (GI-3) is shared by two pathogenic species, B. melitensis and B. abortus. GI-3 encodes mostly unknown proteins. One of the aims of this study was to perform pulsed-field gel electrophoresis (PFGE) on field isolates of B. abortus from Chile to determine whether these isolates are clonally related. Furthermore, we focused on the characterization of GI-3, studying its organization and the genetic conservation of the GI-3 sequence using techniques such as tiling-path PCR (TP-PCR) and restriction fragment length polymorphism-PCR (RFLP-PCR). Our results, after PFGE was performed on 69 field isolates of B. abortus from Chile, showed that the strains were genetically homogeneous. To increase the power of genetic discrimination among these strains, we used multiple locus variable-number tandem-repeat (VNTR) analysis with 16 loci (MLVA-16). The results obtained by MLVA-16 showed that the strains of B. abortus were genetically heterogeneous and that most of them clustered according to their geographic origin. Of the genetic loci studied, panel 2B was the one describing the highest diversity in the analysis, as well as locus Bruce19 in panel 2A. In relation to the study of GI-3, our experimental analysis by TP-PCR identified and confirmed that GI-3 is present in all wild strains of B. abortus, demonstrating the high stability of gene cluster GI-3 in Chilean field strains.

  19. Vadose Zone Transport Field Study: Summary Report

    SciTech Connect

    Ward, Andy L.; Conrad, Mark E.; Daily, William D.; Fink, James B.; Freedman, Vicky L.; Gee, Glendon W.; Hoversten, Gary M.; Keller, Jason M.; Majer, Ernest L.; Murray, Christopher J.; White, Mark D.; Yabusaki, Steven B.; Zhang, Z. F.

    2006-07-31

    From FY 2000 through FY 2003, a series of vadose zone transport field experiments were conducted as part of the U.S. Department of Energy’s Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, and managed by the Pacific Northwest National Laboratory (PNNL). The series of experiments included two major field campaigns, one at a 299-E24-11 injection test site near PUREX and a second at a clastic dike site off Army Loop Road. The goals of these experiments were to improve our understanding of vadose zone transport processes; to develop data sets to validate and calibrate vadose zone flow and transport models; and to identify advanced monitoring techniques useful for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford’s vadose zone. Results of these tests have led to a better understanding of the vadose zone. Fine-scale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy. Conceptual models have been updated to include lateral spreading and numerical models of unsaturated flow and transport have revised accordingly. A new robust model based on the concept of a connectivity tensor was developed to describe saturation-dependent anisotropy in strongly heterogeneous soils and has been incorporated into PNNL’s Subsurface Transport Over Multiple Phases (STOMP) simulator. Application to field-scale transport problems have led to a better understanding plume behavior at a number of sites where lateral spreading may have dominated waste

  20. Differentiation of Erysipelothrix rhusiopathiae strains by nucleotide sequence analysis of a hypervariable region in the spaA gene: discrimination of a live vaccine strain from field isolates.

    PubMed

    Nagai, Shinya; To, Ho; Kanda, Akira

    2008-05-01

    Erysipelothrix rhusiopathiae causes erysipelas in swine and is considered a reemerging disease contributing substantially to economic losses in the swine industry. Since an attenuated live vaccine was commercialized in 1974 in Japan, outbreaks of acute septicemia or subacute urticaria of erysipelas have decreased dramatically. In contrast, a chronic form of erysipelas found during meat inspections in slaughterhouses has been increasing. In this study, a new strain-typing method was developed based on nucleotide sequencing of a hypervariable region in the surface protective antigen (spaA) gene for discrimination of the live vaccine strain from field isolates. Sixteen strains isolated from arthritic lesions found in slaughtered pigs were segregated into 4 major patterns: 1) identical nucleotide sequence with the vaccine strain: 3 isolates; 2) 1 nucleotide substitution (C to A) at position 555: 5 isolates; 3) 1 nucleotide substitution at various positions: 5 isolates; and 4) 2 nucleotide substitutions: 3 isolates. Isolates with the same nucleotide sequence as the vaccine strain were further characterized by other properties, including the mouse pathogenicity test. One strain isolated from pigs on a farm where the live vaccine had been used was found to be closely related to the vaccine strain. The phylogenetic tree constructed based on the spaA sequence suggests that the evolutionary distance of the isolates is related to the pathogenicity in mice. The new strain-typing system based on nucleotide sequencing of the spaA region is useful to discriminate the vaccine strain from field isolates.

  1. Two-dimensional mapping of triaxial strain fields in a multiferroic BiFeO3 thin film using scanning x-ray microdiffraction

    NASA Astrophysics Data System (ADS)

    Bark, Chung W.; Cho, Kyung C.; Koo, Yang M.; Tamura, Nobumichi; Ryu, Sangwoo; Jang, Hyun M.

    2007-03-01

    The dramatically enhanced polarizations and saturation magnetizations observed in the epitaxially constrained BiFeO3 (BFO) thin films with their pronounced grain-orientation dependence have attracted much attention and are attributed largely to the constrained in-plane strain. Thus, it is highly desirable to directly obtain information on the two-dimensional (2D) distribution of the in-plane strain and its correlation with the grain orientation of each corresponding microregion. Here the authors report a 2D quantitative mapping of the grain orientation and the local triaxial strain field in a 250nm thick multiferroic BFO film using a synchrotron x-ray microdiffraction technique. This direct scanning measurement demonstrates that the deviatoric component of the in-plane strain tensor is between 5×10-3 and 6×10-3 and that the local triaxial strain is fairly well correlated with the grain orientation in that particular region.

  2. Largely defocused probe scanning transmission electron microscopy for imaging local modulation of strain field in a hetero interface

    SciTech Connect

    Kim, Suhyun Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum; Oshima, Yoshifumi

    2014-10-13

    We present an innovative method for characterizing the strain field in three dimensions in a hetero interface. Largely defocused probe scanning transmission electron microscopy (LDP-STEM) was employed for imaging the inhomogeneous strain field in a germanium (Ge) layer deposited on a silicon (Si) substrate. In the LDP-STEM image, Ge-atomic columns that are relaxed or strained to the Si substrate in the Si/Ge hetero interface were observed to be distinguishable, allowing for the qualitative characterization of the coherency of the crystal growth. Our results revealed that the strain field is locally modulated along the in-plane direction in the Si/Ge hetero interface.

  3. Electric field controlled strain induced reversible switching of magnetization in Galfenol nanomagnets delineated on PMN-PT substrate

    NASA Astrophysics Data System (ADS)

    Ahmad, Hasnain; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo

    We report a non-volatile converse magneto-electric effect in elliptical Galfenol (FeGa) nanomagnets of ~300 nm lateral dimensions and ~10nm thickness delineated on a PMN-PT substrate. This effect can be harnessed for energy-efficient non-volatile memory. The nanomagnets are fabricated with e-beam lithography and sputtering. Their major axes are aligned parallel to the direction in which the substrate is poled and they are magnetized in this direction with a magnetic field. An electric field in the opposite direction generates compressive strain in the piezoelectric substrate which is partially transferred to the nanomagnets and rotates their magnetization away from the major axes to metastable orientations. There they remain after the field is removed, resulting in non-volatility. Reversing the electric field generates tensile strain which returns the magnetization to the original state. The two states can encode two binary bits which can be written using the correct voltage polarity, resulting in non-toggle behavior. Scaled memory fashioned on this effect can exhibit write energy dissipation of only ~2 aJ. Work is supported by NSF under ECCS-1124714 and CCF-1216614. Sputtering was carried out at NIST Gaithersburg.

  4. Working Group Report: Lattice Field Theory

    SciTech Connect

    Blum, T.; et al.,

    2013-10-22

    This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

  5. Temperature and Field Induced Strain Measurements in Single Crystal Gd5Si2Ge2

    NASA Astrophysics Data System (ADS)

    McCall, S. K.; Nersessian, N.; Carman, G. P.; Pecharsky, V. K.; Schlagel, D. L.; Radousky, H. B.

    2016-06-01

    The first-order magneto-structural transformation that occurs in Gd5Si2Ge2 near room temperature makes it a strong candidate for many energy harvesting applications. Understanding the single crystal properties is crucial for allowing simulations of device performance. In this study, magnetically and thermally induced transformation strains were measured in a single crystal of Gd5Si2.05Ge1.95 as it transforms from a high-temperature monoclinic paramagnet to a lower-temperature orthorhombic ferromagnet. Thermally induced transformation strains of -8500 ppm, +960 ppm and +1800 ppm, and magnetically induced transformation strains of -8500 ppm, +900 ppm and +2300 ppm were measured along the a, b and c axes, respectively. Using experimental data coupled with general thermodynamic considerations, a universal phase diagram was constructed showing the transition from the monoclinic to the orthorhombic phase as a function of temperature and magnetic field.

  6. Strain-Modulated Bandgap and Piezo-Resistive Effect in Black Phosphorus Field-Effect Transistors.

    PubMed

    Zhang, Zuocheng; Li, Likai; Horng, Jason; Wang, Nai Zhou; Yang, Fangyuan; Yu, Yijun; Zhang, Yu; Chen, Guorui; Watanabe, Kenji; Taniguchi, Takashi; Chen, Xian Hui; Wang, Feng; Zhang, Yuanbo

    2017-09-11

    Energy bandgap largely determines the optical and electronic properties of a semiconductor. Variable bandgap therefore makes versatile functionality possible in a single material. In layered material black phosphorus, the bandgap can be modulated by the number of layers; as a result, few-layer black phosphorus has discrete bandgap values that are relevant for optoelectronic applications in the spectral range from red, in monolayer, to mid-infrared in the bulk limit. Here, we further demonstrate continuous bandgap modulation by mechanical strain applied through flexible substrates. The strain-modulated bandgap significantly alters the density of thermally activated carriers; we for the first time observe a large piezo-resistive effect in black phosphorus field-effect transistors (FETs) at room temperature. The effect opens up opportunities for future development of electromechanical transducers based on black phosphorus, and we demonstrate an ultrasensitive strain gauge constructed from black phosphorus thin crystals.

  7. Whole Field Strain Measurement on Complex Surfaces by Digital Speckle Pattern Interferometry

    PubMed Central

    Wang, Yanghong; Thomas, Dan; Zhang, Ping; Yokota, Hiroki; Yang, Lianxiang

    2010-01-01

    Digital Speckle Pattern Interferometry (DSPI), originally known as electronic speckle pattern interferometry (ESPI), is an interferometry based method applicable for conducting 3-dimensional whole field strain characterization. The present DSPI systems are suited for analyzing a relatively simple surface (e.g., a plane surface). However, few existing systems are able to accurately determine strain distributions on a surface with significant contour complexity. Here, we present development of a novel DSPI system that allows strain characterization of a sample with a complex surface. In the described DSPI system, deformations and contours as well as an absolute phase value are determined. Furthermore, variations in measurement sensitivity are considered. We describe a principle and methodology using two examples in the area of mechanical engineering and biomedical engineering, and discuss potential usages and future directions. PMID:21709738

  8. Magnetic-field-induced recovery strain in polycrystalline Ni-Mn-Ga foam

    NASA Astrophysics Data System (ADS)

    Chmielus, Markus; Witherspoon, Cassie; Wimpory, Robert C.; Paulke, Andreas; Hilger, André; Zhang, Xuexi; Dunand, David C.; Müllner, Peter

    2010-12-01

    Recently, we have shown that a polycrystalline Ni-Mn-Ga magnetic shape-memory alloy, when containing two populations of pore sizes, shows very high magnetic-field-induced strain of up to 8.7%. Here, this double-porosity sample is imaged by x-ray microtomography, showing a homogenous distribution of both pore populations. The orientation of six large grains—four with 10M and two with 14M structure—is identified with neutron diffraction. In situ magnetomechanical experiments with a rotating magnetic field demonstrate that strain incompatibilities between misoriented grains are effectively screened by the pores which also stop the propagation of microcracks. During uniaxial compression performed with an orthogonal magnetic bias field, a strain as high as 1% is recovered on unloading by twinning, which is much larger than the elastic value of <0.1% measured without field. At the same time, repeated loading and unloading results in a reduction in the yield stress, which is a training effect similar to that in single crystals.

  9. Near Field Environment Process Model Report

    SciTech Connect

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  10. Field Operations Program Activities Status Report

    SciTech Connect

    J. E. Francfort; D. V. O'Hara; L. A. Slezak

    1999-05-01

    The Field Operations Program is an electric vehicle testing and evaluation program sponsored by US Department of Energy and managed by the Idaho National Engineering and Environmental Laboratory. The Program's goals are to evaluate electric vehicles in real-world applications and environments, support electric vehicle technology advancement, develop infrastructure elements necessary to support significant electric vehicle use, support increased use of electric vehicles in federal fleets, and increase overall awareness and acceptance of electric vehicles. This report covers Program activities from fiscal year 1997 through mid-fiscal year 1999. The Field Operations Program succeeded the Site Operator Program, which ended in September 1996. Electric vehicle testing conducted by the Program includes baseline performance testing (EV America testing), accelerated reliability (life-cycle) testing, and fleet testing. The baseline performance parameters include accelerations, braking, range, energy efficiency, and charging time. The Program collects accelerated reliability and fleet operations data on electric vehicles operated by the Program's Qualified Vehicle Testing (QVT) partners. The Program's QVT partners have over 3 million miles of electric vehicle operating experience.

  11. Extracting full-field dynamic strain response of a rotating wind turbine using photogrammetry

    NASA Astrophysics Data System (ADS)

    Baqersad, Javad; Poozesh, Peyman; Niezrecki, Christopher; Avitabile, Peter

    2015-04-01

    Health monitoring of wind turbines is typically performed using conventional sensors (e.g. strain-gages and accelerometers) that are usually mounted to the nacelle or gearbox. Although many wind turbines stop operating due to blade failures, there are typically few to no sensor mounted on the blades. Placing sensors on the rotating parts of the structure is a challenge due to the wiring and data transmission constraints. Within the current work, an approach to monitor full-field dynamic response of rotating structures (e.g. wind turbine blades or helicopter rotors) is developed and experimentally verified. A wind turbine rotor was used as the test structure and was mounted to a block and horizontally placed on the ground. A pair of bearings connected to the rotor shaft allowed the turbine to freely spin along the shaft. Several optical targets were mounted to the blades and a pair of high-speed cameras was used to monitor the dynamics of the spinning turbine. Displacements of the targets during rotation were measured using three-dimensional point tracking. The point tracking technique measured both rigid body displacement and flexible deformation of the blades at target locations. While the structure is rotating, only flap displacements of optical targets (displacements out of the rotation plane) were used in strain prediction process. The measured displacements were expanded and applied to the finite element model of the turbine to extract full-field dynamic strain on the structure. The proposed approach enabled the prediction of dynamic response on the outer surface as well as within the inner points of the structure where no other sensor could be easily mounted. In order to validate the proposed approach, the predicted strain was compared to strain measured at four locations on the spinning blades using a wireless strain-gage system.

  12. Electronic properties of nanowire superlattices in the presence of strain and magnetic-field effects

    NASA Astrophysics Data System (ADS)

    Willatzen, M.; Voon, L. C. Lew Yan

    2008-08-01

    A calculation of the effective electron barrier potential in quantum-wire superlattices subject to magnetic-field and strain effects is presented. It is shown that, besides the lateral-confinement contributions to the barrier potential emphasized by the authors in earlier work (Lew Yan Voon and Willatzen 2003 J. Appl. Phys. 93 9997; Lew Yan Voon et al 2004 J. Appl. Phys. 96 4660), strong contributions from strain (lattice mismatch) may be present as well. This is due to the fact that strain values can be several percent in heterostructures while electron deformation potentials are of the order of 10 eV. It is also shown that Landau and Landé magnetic-field contributions become important at magnetic fields of 10 T or higher. The driving force behind the lateral-confinement and the Landau magnetic-field contributions is the same, namely, the electron effective-mass difference in the two material constituents forming the superlattice structure; however, the dependences of the two contributions on lateral dimensions are inverse squared and squared, respectively. Similarly, the driving force behind the Landé magnetic-field contribution, being independent of lateral dimensions, is the difference in electron g factors between the two material constituents. We note that, for InAs/GaAs nanowire superlattices, it is possible to tune the effective barrier potential around 0 for cross-sectional dimensions of 5-6 nm by use of a magnetic field. Further, since the effective barrier potential is different for spin-up and spin-down polarized electrons, magnetic-field tuning can be used to separate spin-up and spin-down electrons in quantum-wire superlattices.

  13. Diversity of Proteolytic Clostridium botulinum Strains, Determined by a Pulsed-Field Gel Electrophoresis Approach

    PubMed Central

    Nevas, Mari; Lindström, Miia; Hielm, Sebastian; Björkroth, K. Johanna; Peck, Michael W.; Korkeala, Hannu

    2005-01-01

    Pulsed-field gel electrophoresis (PFGE) was applied to the study of the similarity of 55 strains of proteolytic Clostridium botulinum (C. botulinum group I) types A, AB, B, and F. Rare-cutting restriction enzymes ApaI, AscI, MluI, NruI, PmeI, RsrII, SacII, SmaI, and XhoI were tested for their suitability for the cleavage of DNA of five proteolytic C. botulinum strains. Of these enzymes, SacII, followed by SmaI and XhoI, produced the most convenient number of fragments for genetic typing and were selected for analysis of the 55 strains. The proteolytic C. botulinum species was found to be heterogeneous. In the majority of cases, PFGE enabled discrimination between individual strains of proteolytic C. botulinum types A and B. The different toxin types were discriminated at an 86% similarity level with both SacII and SmaI and at an 83% similarity level with XhoI. Despite the high heterogeneity, three clusters at a 95% similarity level consisting of more than three strains of different origin were noted. The strains of types A and B showed higher diversity than the type F organisms which formed a single cluster. According to this survey, PFGE is to be considered a useful tool for molecular epidemiological analysis of proteolytic C. botulinum types A and B. However, epidemiological conclusions based on PFGE data only should be made with discretion, since highly similar PFGE patterns were noticed, especially within the type B strains. PMID:15746333

  14. Diversity of proteolytic Clostridium botulinum strains, determined by a pulsed-field gel electrophoresis approach.

    PubMed

    Nevas, Mari; Lindström, Miia; Hielm, Sebastian; Björkroth, K Johanna; Peck, Michael W; Korkeala, Hannu

    2005-03-01

    Pulsed-field gel electrophoresis (PFGE) was applied to the study of the similarity of 55 strains of proteolytic Clostridium botulinum (C. botulinum group I) types A, AB, B, and F. Rare-cutting restriction enzymes ApaI, AscI, MluI, NruI, PmeI, RsrII, SacII, SmaI, and XhoI were tested for their suitability for the cleavage of DNA of five proteolytic C. botulinum strains. Of these enzymes, SacII, followed by SmaI and XhoI, produced the most convenient number of fragments for genetic typing and were selected for analysis of the 55 strains. The proteolytic C. botulinum species was found to be heterogeneous. In the majority of cases, PFGE enabled discrimination between individual strains of proteolytic C. botulinum types A and B. The different toxin types were discriminated at an 86% similarity level with both SacII and SmaI and at an 83% similarity level with XhoI. Despite the high heterogeneity, three clusters at a 95% similarity level consisting of more than three strains of different origin were noted. The strains of types A and B showed higher diversity than the type F organisms which formed a single cluster. According to this survey, PFGE is to be considered a useful tool for molecular epidemiological analysis of proteolytic C. botulinum types A and B. However, epidemiological conclusions based on PFGE data only should be made with discretion, since highly similar PFGE patterns were noticed, especially within the type B strains.

  15. Characterization of two bioluminescent Rhizobium meliloti strains constructed for field releases.

    PubMed

    Dammann-Kalinowski, T; Niemann, S; Keller, M; Selbitschka, W; Tebbe, C C; Pühler, A

    1996-05-01

    The deliberate release of genetically engineered microorganisms requires a thorough characterization of the microbes in question. For the two bioluminescent Rhizobium meliloti strains, L1 and L33 [Selbitschka et al. (1992) Mol Ecol 1:9-19; Selbitschka et al. (1995) FEMS Microbiol Ecol 16:223-232], designated for field release, the sites of genetic modifications in the chromosomes were sequenced from amplified genomic DNA. This indicated no unexpected alterations in the nucleotide sequence. The bioluminescent phenotype was stably inherited over more than 100 generations in liquid cultures. The presence of the luciferase gene in both strains did not have secondary effects on a variety of metabolic pathways as assessed by the Biolog GN system. A specific polymerase chain reaction amplification, based on the chromosomal insertion site of the luc cassette, allowed the discrimination between the two strains and thus simplifies monitoring. The RecA-deficient strain L1 showed a strongly (more than 90%) reduced ability to nodulate alfalfa in competition with its parent strain R. meliloti 2011 and its RecA+ counterpart L33.

  16. Electric fields and valence-band offsets at strained [111] heterojunctions

    NASA Astrophysics Data System (ADS)

    Picozzi, S.; Continenza, A.; Freeman, A. J.

    1997-05-01

    Ab initio full-potential linearized augmented plane wave (FLAPW) [H. J. F. Jansen and A. J. Freeman, Phys. Rev. B 30, 561 (1984); M. Weinert, H. Krakauer, E. Wimmer, and A. J. Freeman, ibid. 24, 864 (1981)] calculations have been performed for the [111] ordered common atom strained layer superlattices (in particular, the common-anion GaSb/InSb system and the common-cation InAs/InSb system). We have focused our attention on the potential line up at the two sides of the homopolar isovalent heterojunctions considered, and, in particular, on its dependence on the strain conditions and on the strain induced electric fields. We propose a procedure to locate the interface plane, where the band alignment could be evaluated; furthermore, we suggest that the polarization charges, due to piezoelectric effects, are approximately confined to a narrow region close to the interface and do not affect the potential discontinuity. We find that the interface contribution to the valence band offset is substantially unaffected by strain conditions, whereas the total band line up is highly tunable as a function of the strain conditions. Finally, we compare our results with those obtained for the [001] heterojunctions.

  17. In situ SEM observation of microscale strain fields around a crack tip in polycrystalline molybdenum

    NASA Astrophysics Data System (ADS)

    Li, J. J.; Li, W. C.; Jin, Y. J.; Wang, L. F.; Zhao, C. W.; Xing, Y. M.; Lang, F. C.; Yan, L.; Yang, S. T.

    2016-06-01

    In situ scanning electron microscopy was employed to investigate the crack initiation and propagation in polycrystalline molybdenum under uniaxial tensile load at room temperature. The microscale grid pattern was fabricated using the sputtering deposition technology on the specimen surface covered with a fine square mesh copper grid. The microscale strain fields around the crack tip were measured by geometric phase analysis technique and compared with the theoretical solutions based on the linear elastic fracture mechanics theory. The results showed that as the displacement increases, the crack propagated mainly perpendicular to the tensile direction during the fracture process of molybdenum. The normal strain ɛ xx and shear strain ɛ xy are relatively small, and the normal strain ɛ yy holds a dominant position in the deformation fields and plays a key role in the whole fracture process of molybdenum. With the increase in displacement, the ɛ yy increases rapidly and the two lobes grow significantly but maintain the same shape and orientation. The experimental ɛ yy is in agreement with the theoretical solution. Along the x-axis in front of the crack tip, there is minor discrepancy between the experimental ɛ yy and theoretical ɛ yy within 25 μm from the crack tip, but the agreement between them is very good far from the crack tip (>25 μm).

  18. Near-field/altered-zone models report

    SciTech Connect

    Hardin, E. L., LLNL

    1998-03-01

    lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF/AZ performance. The selection and

  19. The application of strain field intensity method in the steel bridge fatigue life evaluation

    NASA Astrophysics Data System (ADS)

    Zhao, Xuefeng; Wang, Yanhong; Cui, Yanjun; Cao, Kaisheng

    2012-04-01

    Asce's survey shows that 80%--90% bridge damage were associated with fatigue and fracture problems. With the operation of vehicle weight and traffic volume increases constantly, the fatigue of welded steel bridge is becoming more and more serious in recent years. A large number of studies show that most prone to fatigue damage of steel bridge is part of the welding position. Thus, it's important to find a more precise method to assess the fatigue life of steel bridge. Three kinds of fatigue analysis method is commonly used in engineering practice, such as nominal stress method, the local stress strain method and field intensity method. The first two methods frequently used for fatigue life assessment of steel bridge, but field intensity method uses less ,and it widely used in fatigue life assessment of aerospace and mechanical. Nominal stress method and the local stress strain method in engineering has been widely applied, but not considering stress gradient and multiaxial stress effects, the accuracy of calculation stability is relatively poor, so it's difficult to fully explain the fatigue damage mechanism. Therefore, it used strain field intensity method to evaluate the fatigue life of steel bridge. The fatigue life research of the steel bridge based on the strain field method and the fatigue life of the I-section plate girder was analyzed. Using Ansys on the elastoplastic finite element analysis determined the dangerous part of the structure and got the stress-strain history of the dangerous point. At the same time, in order to divide the unit more elaborate introduced the sub-structure technology. Finally, it applies K.N. Smith damage equation to calculate the fatigue life of the dangerous point. In order to better simulating the actual welding defects, it dug a small hole in the welding parts. It dug different holds from different view in the welding parts and plused the same load to calculate its fatigue life. Comparing the results found that the welding

  20. Long-term field release of bioluminescent Sinorhizobium meliloti strains to assess the influence of a recA mutation on the strains' survival.

    PubMed

    Selbitschka, W; Keller, M; Miethling-Graff, R; Dresing, U; Schwieger, F; Krahn, I; Homann, I; Dammann-Kalinowski, T; Pühler, A; Tebbe, C C

    2006-10-01

    A field release experiment was carried out to study the fate of the isogenic, firefly luciferase (luc) gene-tagged Sinorhizobium meliloti strains L1 (RecA-) and L33 (RecA+) in the environment. Both strains were released at concentrations of approximately 10(6) cfu g(-1) soil in replicate and randomized field plots, which had been sown with alfalfa (Medicago sativa). The survival of both strains during the following 7 years could be subdivided into three phases: a sharp decline for more than two orders of magnitude within the first 4 months (phase I), followed by fluctuations around an average number of 10(4) cfu g(-1) soil for nearly 4 years (phase II), and a further decline to approximately 60 cfu g(-1) (phase III). At most sampling dates, no significant differences in the survival of both strains were detected, indicating that the recA gene function was dispensable under these environmental conditions. During the field inoculation, both strains were dispersed accidentally by wind in small numbers to noninoculated field plots. Strain L33 established at a concentration of more than 10(3) cfu g(-1) soil with subsequent seasonal fluctuations. Although strain L1 must have been disseminated to a similar extent, it could never be recovered from noninoculated field plots, indicating that the recA mutation interfered with the strain's capability to establish there. At the beginning of the field experiment, an indigenous alfalfa-nodulating population was below the limit of detection. In the following years, however, an indigenous population arose, which finally outcompeted both strains for saprophytic growth and alfalfa nodulation. RecA- strain L1 was outcompeted for alfalfa nodulation slightly faster than its RecA+ counterpart L33. The diversity of the indigenous population was characterized by employing the Enterobacterial Repetitive Intergenic Consensus polymerase chain reaction fingerprint method. Typing of 2731 root nodule isolates revealed a total of 38 fingerprint

  1. In vitro study of the effect of cyclic strains on the dermal fibroblast (GM3384) morphology--mapping of cell responses to strain field.

    PubMed

    Xie, Kelvin Y; Yang, Lingyan; Chen, Kevin; Li, Qing

    2012-09-01

    Cells can respond to mechanical forces and actively interact with mechanical stimulations in vitro. Understanding the effect of mechanical loading on cell morphology signifies a critical biomechanics issue in tissue engineering. In this study, human dermal fibroblasts (GM3384) underwent cyclic strain. This was done by culturing a monolayer of the cells onto a transparent membrane and applying a cyclic stress using a computer controlled bioreactor. The cells were mechanically stimulated at around 7% strain with 1 cycle per minute for 2 days. Finite element analysis (FEA) was then employed to characterize the strain field across the substrate membrane in the bioreactor. The results showed that strain distribution were non-uniform in the substrate membrane. The mapping of cell morphology with the strain field revealed that the cells exposed to the equibiaxial strain exhibited the classical spindle morphology while the cells subjected to uniaxial strain changed to a polygonal morphology. It is concluded that the nature of the strain has significant impact on the final cell morphology.

  2. Draft Genome Sequence of the Biofilm-Producing Bacillus subtilis Strain B-1, Isolated from an Oil Field

    PubMed Central

    Kesel, S.; Moormann, F.; Gümperlein, I.; Mader, A.; Morikawa, M.; Lieleg, O.

    2014-01-01

    We report here the draft genome sequence of the Bacillus subtilis strain B-1, a strain known to form biofilms. The biofilm matrix mainly consists of the biopolymer γ-polyglutamate (γ-PGA). The sequence of the genome of this strain allows the study of specific genes involved in biofilm formation. PMID:25502661

  3. Molecular characterization of Clostridium tetani strains by pulsed-field gel electrophoresis and colony PCR.

    PubMed

    Plourde-Owobi, Lucile; Seguin, Delphine; Baudin, Marie-Anne; Moste, Catherine; Rokbi, Bachra

    2005-09-01

    Pulsed-field gel electrophoresis and PCR were applied for the first time to the molecular characterization of Clostridium tetani. Among five strains tested, one (CN1339) turned out to contain a mixture of two genetically different clones and two (D11 and G761) to contain bacteria differing by the presence or absence of the 74-kb plasmid harboring the tetX gene.

  4. Molecular Characterization of Clostridium tetani Strains by Pulsed-Field Gel Electrophoresis and Colony PCR

    PubMed Central

    Plourde-Owobi, Lucile; Seguin, Delphine; Baudin, Marie-Anne; Moste, Catherine; Rokbi, Bachra

    2005-01-01

    Pulsed-field gel electrophoresis and PCR were applied for the first time to the molecular characterization of Clostridium tetani. Among five strains tested, one (CN1339) turned out to contain a mixture of two genetically different clones and two (D11 and G761) to contain bacteria differing by the presence or absence of the 74-kb plasmid harboring the tetX gene. PMID:16151158

  5. Tune the electronic and phonon properties of silicene and germanene through biaxial strain and electric field

    NASA Astrophysics Data System (ADS)

    Yan, Jia-An; Stein, Ryan; Coard, Gregory

    2014-03-01

    We presented a density-functional study of the effects of biaxial strain and perpendicular electric field on the electronic and phonon properties of the two-dimensional (2D) silicene and germanene sheets. The two factors can be applied along the parallel and perpendicular directions independently, and therefore increase the tunability on the electronic band structure and phonon properties in these 2D systems. Important quantities such as the Grüneisen parameters will be calculated.

  6. Levels of Reported Stressors and Strains Amongst Schoolteachers: Some UK Data.

    ERIC Educational Resources Information Center

    Fletcher, Ben C.; Payne, Roy L.

    1982-01-01

    Reports the results of an empirical study of psychological stress and strain among teachers. A number of strain variables were sampled: various aspects of job satisfaction and felt pressure; self-esteem assessed against the perceived qualities of other teachers; and clinically validated measures of depression, anxiety, somaticism, and…

  7. Comparison of hatchery and field performance between a whirling-disease-resistant strain and the Ten Sleep strain of rainbow trout.

    PubMed

    Wagner, Eric J; Bartley, Matt; Arndt, Ronney; Oplinger, Randall W; Routledge, M Douglas

    2012-06-01

    A whirling-disease-resistant strain of rainbow trout Oncorhynchus mykiss (GRHL strain) derived from a backcross of an F1 hybrid of two strains (German strain x Harrison Lake strain) with German strain females, was compared with the Ten Sleep (TS) strain of rainbow trout. The GRHL strain had consistently superior growth and feed conversion in two consecutive hatchery trials. Hatching and mortality rates were similar between strains. Both strains were stocked into two Utah reservoirs (Hyrum, Porcupine), and a third, Causey Reservoir, was monitored as a control for seasonal variation in prevalence of Myxobolus cerebralis. A total of 1,323 salmonids captured by gill net in spring and fall sampling between 2006 and 2008 were tested for M. cerebralis via pepsin-trypsin digest methods. Only eight of these (< 1% per species) had clinical signs consistent with whirling disease. In both reservoirs, GRHL survived better than the TS and had higher growth rates. The prevalence of M. cerebralis was significantly lower for GRHL (18.1%) than TS (50.0%) in Porcupine Reservoir. In Hyrum Reservoir the trend was similar, but prevalence was lower and did not significantly differ between GRHL (9.6%) and TS (23.1%). For infected fish, no significant differences were observed between strains in myxospore counts in either Hyrum (GRHL = 911-28,244 spores/fish [spf], TS = 1,822-155,800 spf) or Porcupine (GRHL = 333-426,667spf, TS = 333-230,511 spf) reservoirs. Unmarked rainbow trout in both reservoirs had significantly higher myxospore counts than stocked fish of either strain. There were significant differences in M. cerebralis prevalence and myxospore loads among other naturally reproducing salmonids in the reservoirs. The trend in susceptibility was cutthroat trout Oncorhynchus clarkii > kokanee Oncorhynchus nerka > brown trout Salmo trutta. The GRHL performed well in both hatchery and field settings and is recommended for stocking programs.

  8. Influence of dislocation strain fields on the diffusion of interstitial iron impurities in silicon

    NASA Astrophysics Data System (ADS)

    Ziebarth, Benedikt; Mrovec, Matous; Elsässer, Christian; Gumbsch, Peter

    2015-09-01

    The efficiency of silicon (Si)-based solar cells is strongly affected by crystal defects and impurities. Metallic impurities, in particular interstitial iron (Fe) atoms, cause large electric losses because they act as recombination centers for photogenerated charge carriers. Here, we present a systematic first-principles density functional theory (DFT) study focusing on the influence of hydrostatic, uniaxial, and shear strains on the thermodynamic stability and the diffusivity of Fe impurities in crystalline Si. Our calculations show that the formation energy of neutral Fe interstitials in tetrahedral interstitial sites is almost unaffected by uniform deformations of the Si crystal up to strains of 5%. In contrast, the migration barrier varies significantly with strain, especially for hydrostatic deformation. In order to determine effective diffusion coefficients for different strain states, a kinetic Monte Carlo (kMC) model was set up based on the activation energy barriers and frequency factors obtained from the DFT simulations. By using the strain dependence of the migration barrier, we examined the migration of Fe interstitials in the vicinity of perfect 1 /2 <110 > screw and 60∘ mixed dislocations, and 1 /6 <112 > 90∘ and 30∘ partial dislocations. While the strain field of the perfect screw dislocation always enhances the local Fe diffusion, the existence of tensile and compressive regions around the 60∘ mixed dislocation results in a strong anisotropic diffusion profile with significantly faster and slower diffusivities on its tensile and compressive sides. The influences of the partial dislocations are qualitatively similar to that of the 60∘ mixed dislocation.

  9. Differential reactivity of immune sera from human vaccinees with field strains of eastern equine encephalitis virus.

    PubMed

    Strizki, J M; Repik, P M

    1995-11-01

    Eastern equine encephalitis (EEE) virus is a mosquito-borne alphavirus that can produce a severe and often fatal acute encephalitis in humans, with significant neurologic sequelae in survivors. Due to the serious nature of the disease, an investigational inactivated EEE vaccine (PE-6) is available to individuals at risk for infection. Both serologic and recent molecular analyses of EEE viruses have demonstrated marked differences between the two antigenic varieties of EEE virus, designated North American (NA) and South American (SA). In view of these findings, we have examined the reactivity of sera from three individuals immunized with the EEE vaccine, derived from an NA isolate, with field strains of EEE virus. Anti-EEE serum antibodies from vaccinees reacted strongly in Western blot assays with both of the envelope (E1 and E2) glycoproteins of each NA strain examined, while reactivities with the glycoproteins of SA strains were substantially weaker and variable and dependent upon both the immune response of the vaccinee and the virus isolate assayed. Most striking was the modest to virtual lack of reactivity with the E2 protein of SA strains. Antigenic differences among the glycoproteins of EEE viruses were not as pronounced in immunoprecipitation analysis. Most significantly, although human immune sera displayed high neutralizing titers against each of the NA isolates examined, only negligible neutralizing titers were obtained against SA isolates. These data suggest that immunized individuals would mount an effective antibody response against infection with NA strains of EEE virus, but that further investigation is clearly warranted to fully assess the protective capability of the vaccine against infection with SA strains.

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

    SciTech Connect

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

    2014-09-22

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

  11. Posttranslationally caused bioluminescence burst of the Escherichia coli luciferase reporter strain.

    PubMed

    Ideguchi, Yamato; Oshikoshi, Yuta; Ryo, Masashi; Motoki, Shogo; Kuwano, Takashi; Tezuka, Takafumi; Aoki, Setsuyuki

    2016-01-01

    We continuously monitored bioluminescence from a wild-type reporter strain of Escherichia coli (lacp::luc+/WT), which carries the promoter of the lac operon (lacp) fused with the firefly luciferase gene (luc+). This strain showed a bioluminescence burst when shifted into the stationary growth phase. Bioluminescence profiles of other wild-type reporter strains (rpsPp::luc+ and argAp::luc+) and gene-deletion reporter strains (lacp::luc+/crp- and lacp::luc+/lacI-) indicate that transcriptional regulation is not responsible for generation of the burst. Consistently, changes in the luciferase protein levels did not recapitulate the profile of the burst. On the other hand, dissolved oxygen levels increased over the period across the burst, suggesting that the burst is, at least partially, caused by an increase in intracellular oxygen levels. We discuss limits of the firefly luciferase when used as a reporter for gene expression and its potential utility for monitoring metabolic changes in cells.

  12. Validity of self-reporting and video-recording for measuring knee-straining work postures.

    PubMed

    Jensen, L K; Eenberg, W; Mikkelsen, S

    2000-03-01

    The aim of this study was to compare the validity of self-reporting and video-recording as methods of measuring the duration of knee-straining work postures, and to evaluate the reproducibility of timings of the video-recordings. Thirty-nine carpenters and 33 floorlayers were video-filmed while working, and were asked immediately afterwards to quantify the amount of time spent in knee-straining positions. The investigators recorded the periods of knee-straining work with a stopwatch during playback of the video-film, and the agreement between the two investigators' measurements was studied in 13 pairs of measurements. The video-observation method was very effective for timing knee-strain work. Furthermore, Spearman's correlation coefficient (0.88) indicated a good association between observed and self-reported knee-straining work. Estimation of self-reported knee-straining work collected by interview showed good correlation with measurements of video-recordings. When judging the repeatability of timings of knee-straining work from the video-recordings, a high level of agreement was seen between the two observers in the 13 dual measurements of time spent in knee-straining work positions.

  13. Approximate Analysis on Strain Rate Effects and Behavior of Stress and Strain Fields at the Crack Tip in Mode II in Metallic Materials. Appendix Number 1

    DTIC Science & Technology

    1992-10-01

    increasing the loading rate, specimens smaller in dimensions can be employed in KIC tests at high loading rates. An example of correlation between B and...difficulties arise in numerical simulation of crack behavior at high loading rates. An analytic solution for the stress field at a stationary crack tip in...with prime attention paid to use adequate stress-strain, strain-rate, temperature constitutive relations governing material behavior at the crack tip

  14. Strain gage sting balance 204-6. Calibration report

    NASA Astrophysics Data System (ADS)

    Blaettler, Heinz

    1986-12-01

    The strain gage sting balance 204-6 was developed for aerodynamic measurements on rocket models in the transonic and supersonic wind tunnel. Data are: X = +/- 50 (N); Y = +/- 150 (N); Z = +/- 400 (N); Mx = +/- 1.5 (Nm); My = +/- 20 (Nm); and Mz = +/- 10 (Nm). Compared to the existing balances of same size the ratio Y/Z is changed from 1:8 to 1:3.75. This change of specifications was introduced with regard to measurements to be taken with a sting providing automatic roll positioning around the X-axis. The resistance module was separately constructed and prestressed by a factor of 0.5, and connected to the model and sting part of the balance by electron-beam welding.

  15. Mechanical deformation model of the western United States instantaneous strain-rate field

    USGS Publications Warehouse

    Pollitz, F.F.; Vergnolle, M.

    2006-01-01

    We present a relationship between the long-term fault slip rates and instantaneous velocities as measured by Global Positioning System (GPS) or other geodetic measurements over a short time span. The main elements are the secularly increasing forces imposed by the bounding Pacific and Juan de Fuca (JdF) plates on the North American plate, viscoelastic relaxation following selected large earthquakes occurring on faults that are locked during their respective interseismic periods, and steady slip along creeping portions of faults in the context of a thin-plate system. In detail, the physical model allows separate treatments of faults with known geometry and slip history, faults with incomplete characterization (i.e. fault geometry but not necessarily slip history is available), creeping faults, and dislocation sources distributed between the faults. We model the western United States strain-rate field, derived from 746 GPS velocity vectors, in order to test the importance of the relaxation from historic events and characterize the tectonic forces imposed by the bounding Pacific and JdF plates. Relaxation following major earthquakes (M ??? 8.0) strongly shapes the present strain-rate field over most of the plate boundary zone. Equally important are lateral shear transmitted across the Pacific-North America plate boundary along ???1000 km of the continental shelf, downdip forces distributed along the Cascadia subduction interface, and distributed slip in the lower lithosphere. Post-earthquake relaxation and tectonic forcing, combined with distributed deep slip, constructively interfere near the western margin of the plate boundary zone, producing locally large strain accumulation along the San Andreas fault (SAF) system. However, they destructively interfere further into the plate interior, resulting in smaller and more variable strain accumulation patterns in the eastern part of the plate boundary zone. Much of the right-lateral strain accumulation along the SAF

  16. Full-Field Strain Measurement On Titanium Welds And Local Elasto-Plastic Identification With The Virtual Fields Method

    SciTech Connect

    Tattoli, F.; Casavola, C.; Pierron, F.; Rotinat, R.; Pappalettere, C.

    2011-01-17

    One of the main problems in welding is the microstructural transformation within the area affected by the thermal history. The resulting heterogeneous microstructure within the weld nugget and the heat affected zones is often associated with changes in local material properties. The present work deals with the identification of material parameters governing the elasto--plastic behaviour of the fused and heat affected zones as well as the base material for titanium hybrid welded joints (Ti6Al4V alloy). The material parameters are identified from heterogeneous strain fields with the Virtual Fields Method. This method is based on a relevant use of the principle of virtual work and it has been shown to be useful and much less time consuming than classical finite element model updating approaches applied to similar problems. The paper will present results and discuss the problem of selection of the weld zones for the identification.

  17. Full-Field Strain Measurement On Titanium Welds And Local Elasto-Plastic Identification With The Virtual Fields Method

    NASA Astrophysics Data System (ADS)

    Tattoli, F.; Pierron, F.; Rotinat, R.; Casavola, C.; Pappalettere, C.

    2011-01-01

    One of the main problems in welding is the microstructural transformation within the area affected by the thermal history. The resulting heterogeneous microstructure within the weld nugget and the heat affected zones is often associated with changes in local material properties. The present work deals with the identification of material parameters governing the elasto—plastic behaviour of the fused and heat affected zones as well as the base material for titanium hybrid welded joints (Ti6Al4V alloy). The material parameters are identified from heterogeneous strain fields with the Virtual Fields Method. This method is based on a relevant use of the principle of virtual work and it has been shown to be useful and much less time consuming than classical finite element model updating approaches applied to similar problems. The paper will present results and discuss the problem of selection of the weld zones for the identification.

  18. Effect of Strain Field on Threshold Displacement Energy of Tungsten Studied by Molecular Dynamics Simulation

    SciTech Connect

    Wang, Dong; Gao, Ning; Setyawan, W.; Kurtz, R. J.; Wang, Zhi-Guang; Gao, Xing; He, Wen-Hao; Pang, Li-Long

    2016-09-01

    The influence of strain field on defect formation energy and threshold displacement energy (Ed) in body-centered cubic (BCC) tungsten (W) has been studied with molecular dynamics simulations. Two different W potentials (Fikar and Juslin) were compared and the results indicate that the connection distance and selected function linking the short-range and long-range portions of the potentials affects the threshold displacement energy and its direction-specific values. The minimum Ed direction calculated with the Fikar-potential is <100> and with the Juslin-potential is <111>. Nevertheless, the most stable self-interstitial configuration is found to be a <111>-crowdion for both potentials. This stable configuration does not change with applied strain. Varying the strain from compression to tension increases the vacancy formation energy but decreases the self-interstitial formation energy. The formation energy of a self-interstitial changes more significantly than a vacancy such that Ed decreases with applied hydrostatic strain from compression to tension.

  19. Survival and development of ivermectin-resistant or susceptible strains of Haemonchus contortus under field and laboratory conditions.

    PubMed

    Echevarria, F A; Armour, J; Borba, M F; Duncan, J L

    1993-03-01

    The free-living development of three strains of Haemonchus contortus was studied in two experiments. Day 21 faecal samples were collected from lambs infected with either a susceptible strain, a laboratory-selected ivermectin (IVM) resistant strain or a South African field strain showing multiple anthelmintic resistance, which included IVM. No eggs hatched in samples cultured at 4 or 10 degrees C. At 22 degrees C the laboratory-selected strain showed the highest rate of development while at 27 degrees C the susceptible strain produced the highest yield of third stage larvae (L3): at both temperatures the field strain showed the lowest percentage development to L3. The second experiment was a field study carried out in southern Brazil. Faeces containing either an IVM-susceptible or an IVM-resistant strain of H contortus were placed in two series of grass plots during each of three summer months. Soil subsequently yielded more larvae than did grass suggesting migration or mechanical transport into the soil. For plots contaminated during the first two months there was no significant difference in recovery rate between the two strains (P > 0.05). When contamination occurred during the third month, the IVM-resistant strain produced significantly higher recovery rates (P < 0.05) from both pasture and soil.

  20. The unique effect of in-plane anisotropic strain in the magnetization control by electric field

    NASA Astrophysics Data System (ADS)

    Zhao, Y. Y.; Wang, J.; Hu, F. X.; Liu, Y.; Kuang, H.; Wu, R. R.; Sun, J. R.; Shen, B. G.

    2016-05-01

    The electric field control of magnetization in both (100)- and (011)-Pr0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PSMO/PMN-PT) heterostructures were investigated. It was found that the in-plane isotropic strain induced by electric field only slightly reduces the magnetization at low temperature in (100)-PSMO/PMN-PT film. On the other hand, for (011)-PSMO/PMN-PT film, the in-plane anisotropic strain results in in-plane anisotropic, nonvolatile change of magnetization at low-temperature. The magnetization, remanence and coercivity along in-plane [100] direction are suppressed by the electric field while the ones along [01-1] direction are enhanced, which is ascribed to the extra effective magnetic anisotropy induced by the electric field via anisotropic piezostrains. More interestingly, such anisotropic modulation behaviors are nonvolatile, demonstrating a memory effect.

  1. Quantitative full-field strain measurements by SAOED (SrAl2O4:Eu2+,Dy3+) mechanoluminescent materials

    NASA Astrophysics Data System (ADS)

    Imani Azad, Ali; Rahimi, Mohammad Reza; Yun, Gun Jin

    2016-09-01

    In this paper, a new calibration method for mechano-luminescence (ML) thin film sensors was proposed to enable quantitative full-field strain measurements in pixel-level resolution for the first time along with two standard reference test methods. The proposed method has a distinct advantage of its facet-free full-field strain sensing capability with pixel-level resolution. For the ML sensor, standard reference test methods were proposed for developing calibrated relationships between ML light intensity and effective strains: (1) uniaxial tensile reference test and (2) non-uniform strain reference test. From the reference tests, two different calibration models were developed in a recurrence equation form and validated measuring general strain distributions on different experimental specimens. Verified finite element (FE) simulation results were compared with ML effective strains to confirm its accuracy. The comparisons of the ML effective strains with FE simulation results showed that the calibration models can acceptably measure full-field strains. Limitations, sources of errors, suggestions for improving accuracy and practical considerations were also discussed. A conclusion of this research is that the proposed method enables ML sensing films to measure quantitative full-field strain distributions.

  2. Calculating Strain Rate Field for Active Fault in Small Area Based on GPS and InSAR Geodetic Observations

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Shan, X.; Song, X.

    2016-12-01

    How to estimate strain rate field of active faults is a key question in geophysics science. With the rapid development of geodetic techniques, GPS and InSAR are powerful techniques to monitor crustal deformation, and provide essential dataset for strain rate calculation. However, there are multiple methods of calculating strain rate field, and some of them may lead to entirely different results even with common data. Two experiments are conducted in this study, and all of them are based on simulated data. The aim of the first experiment is to compare three methods of calculating strain rate, I: triangular mesh method, II: neighboring point method in Cartesian coordinate system, whose weight is a function of distance, III: our method-applying method II in spherical coordinate system. The theoretical GPS velocity field and strain rate field are designed with resolution of 0.01, and close to an active fault. Observation velocity field is processed sparsely to 0.1 from theoretical velocity field. Three methods are used to compute strain rate field based on observation velocity field, and the results indicate that (1) result of method I is not smooth due to the mesh network, and several areas with high strain rate are unexpected; (2) results of method II and III are smooth, and their spatial patterns fit the theoretical strain rate field; (3) RMS magnitude related to coordinate system is same as magnitude of theoretical strain rate field. In real case, observation error is inevitable in GPS data, so random error is added in the second experiment. Based on method III, we calculate strain rate field from GPS data with observation error. The result shows that observation error causes a gross distortion. Then we add InSAR with random error to GPS data, and the result shows that based on the combination of GPS and InSAR, RMS magnitude of velocity field and strain rate field is much smaller than that based on GPS only. This experiment suggests that combining GPS and In

  3. Second order nonlinearity in Si by inhomogeneous strain and electric fields

    NASA Astrophysics Data System (ADS)

    Schilling, Jörg; Schriever, Clemens; Bianco, Federica; Cazzanelli, Massimo; Pavesi, Lorenzo

    2015-08-01

    The lack of a dipolar second order susceptibility (χ(2)) in silicon due to its centro-symmetric diamond lattice usually inhibits efficient second order nonlinear optical processes in the silicon bulk. Depositing stressed silicon nitride layers or growing a thermal oxide layer introduces an inhomogeneous strain into the silicon lattice and breaks the centro-symmetry of its crystal structure thereby creating a χ(2). This causes enhanced second harmonic generation and was observed in reflection and transmission measurements for wavelengths in the infrared. However strain is not the only means to break the structures symmetry. Fixed charges at the silicon nitride/silicon interface cause a high electric field close to the silicon interface which causes electric-field-induced-second-harmonic (EFISH) contributions too. The combination of both effects leads to χ(2) values which are estimated to be of the order as classic χ(2) materials like KDP or LiNiO3. This paves the way for the exploitation of other second order nonlinear processes in the area of silicon photonics and is an example how fundamental optical properties of materials can be altered by strain.

  4. Field validation of road roughness evaluation using in-pavement strain sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Deng, F.; Huang, Y.; Bridgelall, R.

    2016-04-01

    Most transportation agencies now collect pavement roughness data using the inertial profilers, which requires instrumented vehicles and technicians with specialized training to interpret the results. The extensive labor requirements of the profiling activities limit data collection for portions of the national highway system to at most once per year, resulting in outdated roughness data for decision making of maintenance needs. In this paper, a real-time roughness evaluation method was developed by linking the output of durable in-pavement strain sensors to road roughness level. The durable in-pavement sensors will continuously provide information of road roughness in real time after they are installed and calibrated during the road construction until the service life of the associated pavement. Field tests validated the developed strain method by comparison with standard inertial profiling method and the connected-vehicle method. The comparison of the results from the field tests approves the effectiveness of the developed road roughness evaluation method using in-pavement strain sensors, which can be further applied practically for needed concrete pavements.

  5. The dynamic Virtual Fields Method on rubbers at medium and high strain rates

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Ho; Siviour, Clive R.

    2015-09-01

    Elastomeric materials are widely used for energy absorption applications, often experiencing high strain rate deformations. The mechanical characterization of rubbers at high strain rates presents several experimental difficulties, especially associated with achieving adequate signal to noise ratio and static stress equilibrium, when using a conventional technique such as the split Hopkinson pressure bar. In the present study, these problems are avoided by using the dynamic Virtual Fields Method (VFM) in which acceleration fields, clearly generated by the non-equilibrium state, are utilized as a force measurement with in the frame work of the principle of virtual work equation. In this paper, two dynamic VFM based techniques are used to characterise an EPDM rubber. These are denoted as the linear and nonlinear VFM and are developed for (respectively) medium (drop-weight) and high (gas-gun) strain-rate experiments. The use of the two VFMs combined with high-speed imaging analysed by digital imaging correlation allows the identification of the parameters of a given rubber mechanical model; in this case the Ogden model is used.

  6. Optical characterization of acceleration-induced strain fields in inhomogeneous brain slices.

    PubMed

    Lauret, C; Hrapko, M; van Dommelen, J A W; Peters, G W M; Wismans, J S H M

    2009-04-01

    The aim of this study was to measure high-resolution strain fields in planar sections of brain tissue during translational acceleration to obtain validation data for numerical simulations. Slices were made from fresh, porcine brain tissue, and contained both grey and white matter as well as the complex folding structure of the cortex. The brain slices were immersed in artificial cerebrospinal fluid (aCSF) and were encapsulated in a rigid cavity representing the actual shape of the skull. The rigid cavity sustained an acceleration of about 900m/s(2) to a velocity of 4m/s followed by a deceleration of more than 2000m/s(2). During the experiment, images were taken using a high-speed video camera and Von Mises strains were calculated using a digital image correlation technique. The acceleration of the sampleholder was determined using the same digital image correlation technique. A rotational motion of the brain slice relative to the sampleholder was observed, which may have been caused by a thicker posterior part of the slice. Local variations in the displacement field were found, which were related to the sulci and the grey and white matter composition of the slice. Furthermore, higher Von Mises strains were seen in the areas around the sulci.

  7. Genetic characterization of vaccine and field strains of serotype A foot-and-mouth disease virus from India.

    PubMed

    Mohapatra, J K; Pawar, S S; Tosh, C; Subramaniam, S; Palsamy, R; Sanyal, A; Hemadri, D; Pattnaik, B

    2011-01-01

    Extreme antigenic and genetic heterogeneity of serotype A foot-and-mouth disease virus (FMDV) population has resulted in change of vaccine strains in India twice in the last decade. In such a situation, complete characterization of the vaccine strains is imperative. With regard to the frequent outbreaks of this disease, FMDV field strains are also of interest. Therefore three vaccine strains and two field strains of type A FMDV from India were completely sequenced and the obtained sequences were subjected to sequence and phylogenetic analyses. Based on the complete coding region, all the Indian strains clustered in the Asia topotype and exhibited a more than 11% nt divergence from the other Asian strains. The 5'-UTR of some Indian strains revealed block deletions of 43 and 86 nt corresponding to the pseudoknot region. Amino acids S44 in VP2 and F164 in VP1 were found to be the exclusive signatures for the Asia topotype. The vaccine strains differed at 65 aa positions in the capsid region, 13 of them antigenically critical. Variability at such positions is likely to affect the antigenic profile of these strains. Complete genome sequences of the vaccine strains presented here could serve as the reference for any comparative genomics in future.

  8. Field study of vaccination of cattle with Brucella abortus strains RB51 and 19 under high and low disease prevalence.

    PubMed

    Lord, V R; Schurig, G G; Cherwonogrodzky, J W; Marcano, M J; Melendez, G E

    1998-08-01

    To assess humoral and protective immunity in cattle vaccinated by 12 months with Brucella abortus vaccine strains RB51 and 19 under field conditions of high and low brucellosis prevalence. 450 seronegative female cattle: 330 three to eight months old (calves), and 120 ten to twelve months old (heifers). Ranch A had high prevalence (39%) of brucellosis, and ranch B had low prevalence (2%), as determined by results of conventional serologic testing: agar gel immunodiffusion and the ring test. Seronegative cattle were vaccinated once or twice with 5 x 10(9) colony-forming units of B abortus strain RB51 or once with strain 19. After vaccinating 285 cattle with strain RB51 and 165 with strain 19, 74 (26%) and 30 (18%), respectively, were bred to seropositive bulls, then were kept within the infected herd of origin. All cattle vaccinated with strain 19 seroconverted 30 days later. All 285 cattle vaccinated with strain RB51 had negative results for all serologic tests, including agar gel immunodiffusion. All RB51-vaccinated cattle that became pregnant had negative results for the ring test and for conventional serologic tests after their first calving. Strain RB51 can be used as a live organism vaccine without inducing antibody titers that interfere with serodiagnosis, and induced 100% protection against field strain B abortus-induced abortion in cattle vaccinated at least 1 year before mating to an infected bull. Vaccination with strain 19 under similar conditions was less effective than vaccination with strain RB51.

  9. Orientation effect on the giant stress field induced in a single Ni nanowire by mechanical strain

    NASA Astrophysics Data System (ADS)

    Melilli, G.; Madon, B.; Clochard, M.-C.; Wegrowe, J.-E.

    2015-09-01

    The change of magnetization (i.e. using the inverse magnetostriction effect) allows to investigate at the nanoscale the effects of thermoelastic and piezoelectric strain of an active track-etched β-PVDF polymer matrix on an electrodeposited single-contacted Ni nanowire (NW). The magnetization state is measured locally by anisotropic magnetoresitance (AMR). The ferromagnetic NW plays thus the role of a mechanical probe that allows the effects of mechanical strain to be characterized and described qualitatively and quantitatively. Due to the inverse magnetostriction, a quasi-disappearance of the AMR signal for a variation of the order of ΔT ≍ 10 K has been evidenced. The coplanarity of the vectors between the magnetization and the magnetic field is broken. A way of studying the effect of the geometry on such a system, is to fabricate oriented polymer templates. Track-etched polymer membranes were thus irradiated at various angles (αirrad) leading, after electrodeposition, to embedded Ni NWs of different orientations. With cylindrical Ni NW oriented normally to the template surface, the induced stress field in a single Ni NW was found 1000 time higher than the bulk stress field (due to thermal expansion measured on the PVDF). This amplification results in three nanoscopic effects: (1) a stress mismatch between the Ni NW and the membrane, (2) a non-negligible role of the surface tension on Ni NW Young modulus, and (3) the possibility of non-linear stress-strain law. When the Ni NWs are tilted from the polymer template surface normality, the induced stress field is reduced and the amplification phenomenon is less important.

  10. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect

    Barabash, Rozaliya; Xu, Ruqing; Barabash, Oleg M; Sozinov, Alexei

    2014-01-01

    Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

  11. Statistics of vertical vorticity, divergence, and strain in a developed submesoscale turbulence field

    NASA Astrophysics Data System (ADS)

    Shcherbina, Andrey Y.; D'Asaro, Eric A.; Lee, Craig M.; Klymak, Jody M.; Molemaker, M. Jeroen; McWilliams, James C.

    2013-09-01

    detailed view of upper ocean vorticity, divergence, and strain statistics was obtained by a two-vessel survey in the North Atlantic Mode Water region in winter 2012. Synchronous Acoustic Doppler Current Profiler sampling provided the first in situ estimates of the full velocity gradient tensor at O(1 km) scale without the usual mix of spatial and temporal aliasing. The observed vorticity distribution in the mixed layer was markedly asymmetric (skewness 2.5), with sparse strands of strong cyclonic vorticity embedded in a weak, predominantly anticyclonic background. Skewness of the vorticity distribution decreased linearly with depth, disappearing completely in the pycnocline. Statistics of divergence and strain rate generally followed the normal and χ distributions, respectively. These observations confirm a high-resolution numerical model prediction for the structure of the active submesoscale turbulence field in this area.

  12. Local strain field fluctuations in quasi-two-dimensional colloidal glasses

    NASA Astrophysics Data System (ADS)

    Xu, Ye; Still, Tim; Aptowicz, Kevin; Yodh, Arjun

    2013-03-01

    We investigate the local strain field fluctuations in a quasi-two-dimensional colloidal glass as a function of packing fraction as the jamming transition is approached. Using standard video microscopy and particle tracking techniques, we derive the best-fit affine strain tensor and the non-affinity for each particle in the sample; this information is obtained by analyzing the variations of local configurations around each particle due to thermal motion. The spatial and temporal distributions of this local deformation permit us to probe the mechanical properties of our colloidal systems. We study how these mechanical properties evolve as the systems approaches the jamming transition. Furthermore, we explore the connection between the mechanical heterogeneity and the onset of irreversible rearrangements. We gratefully acknowledge financial support from the National Science Foundation through DMR12-05463, the PENN MRSEC DMR11-20901, NASA NNX08AO0G, and COMPASS

  13. Local strain fields in two-dimensional colloidal crystals with bond strength disorder

    NASA Astrophysics Data System (ADS)

    Gratale, Matthew; Xu, Ye; Still, Tim; Yodh, Arjun

    2013-03-01

    We study the local strain fields of two-dimensional colloidal crystals consisting of random distributions of hard polystyrene particles and soft microgel particles. Using standard video microscopy and particle tracking techniques, we analyze the variations of local configurations around each particle due to thermal motion. With this information we derive the best-fit affine strain tensor and the non-affinity for each particle in the sample, which allow us to study the mechanical properties of our colloidal crystals. We than observe the changes in these properties as we transition from a predominately hard-sphere crystal to predominately soft-sphere crystal, that is we explore how the mechanical properties are affected by replacing hard inter-particle bonds with soft inter-particle bonds. We gratefully acknowledge financial support from the National Science Foundation through DMR12-05463, the PENN MRSEC DMR11-20901, and NASA NNX08AO0G.

  14. Whole field displacement and strain rosettes by grating objective speckle method

    NASA Astrophysics Data System (ADS)

    Tu, Meirong; Gielisse, Peter J.; Xu, Wei

    1991-12-01

    The grating objective speckle method was applied for whole field displacement measurements to a high transition temperature superconductor (YBa2Cu3Ox) disk under diametral-compression. Four fringe patterns were obtained from one single specklegram, indicating the displacement components along four different directions, with 45 degree intervals. The spatial frequencies, which represent the sensitivities of the fringe intervals, were 2400 lines/mm for Ux and Uy, and 1697 lines/mm for U45 and U135, respectively. The normal strain components, (epsilon) x, (epsilon) y, (epsilon) 135, can be directly transformed. The shear strain, (gamma) xy, can therefore be calculated by the rosette equations without the need for first cross-derivatives from two displacement contour maps, which is highly sensitive to accidental rigid-body rotations. The technique provides an extremely simple set-up for the recording system. There is no laser, no camera, no laborious optical alignment, and no requirement for vibration isolation.

  15. [Multidrug-Resistant Tuberculosis by Strains of Beijing Family, in Patients from Lisbon, Portugal: Preliminary Report].

    PubMed

    Maltez, Fernando; Martins, Teresa; Póvoas, Diana; Cabo, João; Peres, Helena; Antunes, Francisco; Perdigão, João; Portugal, Isabel

    2017-03-31

    Beijing family strains of Mycobacterium tuberculosis are associated with multidrug-resistance. Although strains of the Lisboa family are the most common among multidrug-resistant and extensively drug-resistant patients in the region, several studies have reported the presence of the Beijing family. However, the features of patients from whom they were isolated, are not yet known. Retrospective study involving 104 multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis, from the same number of patients, isolated and genotyped between 1993 and 2015 in Lisbon. We assessed the prevalence of strains of both families and the epidemiologic and clinical features of those infected with Beijing family strains. Seventy-four strains (71.2%) belonged to the Lisboa family, 25 (24.0%) showed a unique genotypic pattern and five (4.8%) belonged to the Beijing family, the latter identified after 2009. Those infected with Beijing family strains were angolan (n = 1), ukrainian (n = 2) and portuguese (n = 2), mainly young-aged and, four of five immunocompetent and with no past history of tuberculosis. All had multidrug-resistant tuberculosis. We did not find any distinctive clinical or radiological features, neither a predominant resistance pattern. Cure rate was high (four patients). Although the number of infected patients with Beijing strains was small, it suggests an important proportion of primary tuberculosis, a potential for transmission in the community but also a better clinical outcome when compared to other reported strains, such as W-Beijing and Lisboa. Although Lisboa family strains account for most of the multidrug and extensively drug-resistant tuberculosis cases in Lisbon area, Beijing strains are transmitted in the city and might change the local characteristics of the epidemics.

  16. 43 CFR 3.13 - Report of field officer.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Report of field officer. 3.13 Section 3.13 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.13 Report of field officer. The field officer in charge of land owned or controlled by the...

  17. 43 CFR 3.13 - Report of field officer.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Report of field officer. 3.13 Section 3.13 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.13 Report of field officer. The field officer in charge of land owned or controlled by the...

  18. 43 CFR 3.13 - Report of field officer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Report of field officer. 3.13 Section 3.13 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.13 Report of field officer. The field officer in charge of land owned or controlled by the...

  19. 43 CFR 3.13 - Report of field officer.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Report of field officer. 3.13 Section 3.13 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.13 Report of field officer. The field officer in charge of land owned or controlled by the...

  20. 43 CFR 3.13 - Report of field officer.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Report of field officer. 3.13 Section 3.13 Public Lands: Interior Office of the Secretary of the Interior PRESERVATION OF AMERICAN ANTIQUITIES § 3.13 Report of field officer. The field officer in charge of land owned or controlled by the...

  1. In vitro activity of tylvalosin against Spanish field strains of Mycoplasma hyopneumoniae.

    PubMed

    Tavío, M M; Poveda, C; Assunção, P; Ramírez, A S; Poveda, J B

    2014-11-29

    Mycoplasma hyopneumoniae is involved in the porcine enzootic pneumonia and respiratory disease complex; therefore, the search for new treatment options that contribute to the control of this organism is relevant. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations of tylvalosin and 19 other antimicrobial agents against 20 Spanish field isolates of M. hyopneumoniae were determined using the broth microdilution method, with the type strain (J) as a control strain. Tylvalosin had MIC50 and MIC90 values of 0.016 and 0.06 µg/ml, respectively, and was the second-most effective of the assayed antibiotics, after valnemulin. Tiamulin, tylosin and lincomycin were also among the antibiotics with the lowest MIC50 and MIC90 values against the 20 field isolates (0.06-0.25 µg/ml). However, resistance to tylosin and spiramycin, which like tylvalosin, are 16-membered macrolides, was observed. The MIC50 and MIC90 values for ciprofloxacin and enrofloxacin ranged from 0.125 to 1 µg/ml; the corresponding values ranged from 2 to 4 µg/ml for oxytetracyline, which was the most active tetracycline. Furthermore, tylvalosin and valnemulin exhibited the highest bactericidal activities. In conclusion, the macrolide tylvalosin and the pleuromutilin valnemulin exhibited the highest in vitro antimicrobial activities against M. hyopneumoniae field isolates in comparison with the other tested antibiotics.

  2. The 3-D strain patterns in Turkey using geodetic velocity fields from the RTK-CORS (TR) network

    NASA Astrophysics Data System (ADS)

    Kutoglu, Hakan Senol; Toker, Mustafa; Mekik, Cetin

    2016-03-01

    This study presents our use of GPS data to obtain and quantify the full continuous strain tensor using a 3-D velocity field in Turkey. In this study, GPS velocities improve the estimation of short-term strain tensor fields for determining the seismic hazard of Turkey. The tensorial analysis presents different aspects of deformation, such as the normal and shear strains, including their directions, the compressional and extensional strains. This analysis is appropriate for the characterizing the state of the current seismic deformation. GPS velocity data from continuous measurements (2009-2012) to estimate deformations were processed using the GAMIT/GLOBK software. Using high-rate GPS data from permanent 146 GNSS stations (RTK-CORS-TR network), the strain distribution was determined and interpolated using a biharmonic spline technique. We show the strain field patterns within axial and plane form at several critical locations, and discuss these results within the context of the seismic and tectonic deformation of Turkey. We conclude that the knowledge of the crustal strain patterns provides important information on the location of the main faults and strain accumulation for the hazard assessment. The results show an agreement between the seismic and tectonic strains confirming that there are active crustal deformations in Turkey.

  3. Enriched Open Field Facilitates Exercise and Social Interaction in 2 Strains of Guinea Pigs (Cavia porcellus)

    PubMed Central

    Brewer, Jacob S; Bellinger, Seanceray A; Joshi, Prianca; Kleven, Gale A

    2014-01-01

    Current housing guidelines for laboratory rodents include recommendations for enrichment. Working with guinea pigs, we have developed an open-field enrichment paradigm that provides several aspects of this species’ natural environment. These naturalistic aspects include access to increased space for exploration, access to western timothy (Phleum pratense L.) hay, and grouping as a herd to facilitate social interaction. To determine the immediate effect on behavior from access to the enriched environment, female guinea pigs from 2 strains, IAF Hairless and NIH Hartley, were observed in both standard home cages and an open-field enriched environment. Subjects were housed with cagemates in pairs for the home-cage observation and were grouped as a herd when in the open-field arena. Behaviors were videorecorded for 1 h and then scored. Salivary cortisol levels were measured both prior to and immediately after behavioral observations. Analyses revealed higher levels of activity and social interaction in the open-field arena compared with the home cage, with no significant change in salivary cortisol levels. These results suggest that exposure to the open-field environment provide increased opportunities for exercise and social enrichment. Although additional studies are needed to determine long-term effects on experimental outcomes, the open-field configuration holds promise as a laboratory enrichment paradigm for guinea pigs. PMID:25199089

  4. Microbial control of emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) with Beauveria bassiana strain GHA: Greenhouse and field trials

    Treesearch

    Houping Liu; Leah S. Bauer

    2008-01-01

    In 2003-2004, the lethal and sublethal effects of Beauveria bassiana strain GHA on emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) adults and larvae were evaluated using topical spray and fungal band treatments in the greenhouse and field. B. bassiana strain GHA was moderately effective against...

  5. Draft Genome Sequences of Two Janthinobacteriumlividum Strains, Isolated from Pristine Groundwater Collected from the Oak Ridge Field Research Center.

    PubMed

    Wu, Xiaoqin; Deutschbauer, Adam M; Kazakov, Alexey E; Wetmore, Kelly M; Cwick, Bryson A; Walker, Robert M; Novichkov, Pavel S; Arkin, Adam P; Chakraborty, Romy

    2017-06-29

    We present here the draft genome sequences of two Janthinobacterium lividum strains, GW456P and GW458P, isolated from groundwater samples collected from a background site at the Oak Ridge Field Research Center. Production of a purple pigment by these two strains was observed when grown on diluted (1/10) LB agar plates. Copyright © 2017 Wu et al.

  6. Treatment of multiple resistant field strain of Ostertagia spp. in Cashmere and Angora goats.

    PubMed

    Várady, M; Praslicka, J; Corba, J

    1994-05-01

    A multiple resistant field strain of gastro-intestinal nematodes was detected in Cashmere and Angora goats imported from New Zealand. Different treatments with three types of broad spectrum anthelmintics (albendazole, levamisole/tetramisole and ivermectin) at various dose rates are described. Satisfactory effect in Angora goats was not achieved until all three anthelmintics were administered simultaneously at twice the normal sheep dose. Post mortem worm counts and identification revealed that the resistant population consisted of 89% Ostertagia circumcincta, 6% Ostertagia ostertagi and 5% Ostertagia trifurcata. However, egg hatch assay carried out seven months later detected the presence of resistant nematodes again.

  7. Tuning Magnetism and Electronic Phase Transitions by Strain and Electric Field in Zigzag MoS2 Nanoribbons.

    PubMed

    Kou, Liangzhi; Tang, Chun; Zhang, Yi; Heine, Thomas; Chen, Changfeng; Frauenheim, Thomas

    2012-10-18

    Effective modulation of physical properties via external control may open various potential nanoelectronic applications of single-layer MoS2 nanoribbons (MoS2NRs). We show by first-principles calculations that the magnetic and electronic properties of zigzag MoS2NRs exhibit sensitive response to applied strain and electric field. Tensile strain in the zigzag direction produces reversible modulation of magnetic moments and electronic phase transitions among metallic, half-metallic, and semiconducting states, which stem from the energy-level shifts induced by an internal electric polarization and the competing covalent/ionic interactions. A simultaneously applied electric field further enhances or suppresses the strain-induced modulations depending on the direction of the electric field relative to the internal polarization. These findings suggest a robust and efficient approach to modulating the properties of MoS2NRs by a combination of strain engineering and electric field tuning.

  8. Phylogenomics of Xanthomonas field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity

    PubMed Central

    Schwartz, Allison R.; Potnis, Neha; Timilsina, Sujan; Wilson, Mark; Patané, José; Martins, Joaquim; Minsavage, Gerald V.; Dahlbeck, Douglas; Akhunova, Alina; Almeida, Nalvo; Vallad, Gary E.; Barak, Jeri D.; White, Frank F.; Miller, Sally A.; Ritchie, David; Goss, Erica; Bart, Rebecca S.; Setubal, João C.; Jones, Jeffrey B.; Staskawicz, Brian J.

    2015-01-01

    Bacterial spot disease of pepper and tomato is caused by four distinct Xanthomonas species and is a severely limiting factor on fruit yield in these crops. The genetic diversity and the type III effector repertoires of a large sampling of field strains for this disease have yet to be explored on a genomic scale, limiting our understanding of pathogen evolution in an agricultural setting. Genomes of 67 Xanthomonas euvesicatoria (Xe), Xanthomonas perforans (Xp), and Xanthomonas gardneri (Xg) strains isolated from diseased pepper and tomato fields in the southeastern and midwestern United States were sequenced in order to determine the genetic diversity in field strains. Type III effector repertoires were computationally predicted for each strain, and multiple methods of constructing phylogenies were employed to understand better the genetic relationship of strains in the collection. A division in the Xp population was detected based on core genome phylogeny, supporting a model whereby the host-range expansion of Xp field strains on pepper is due, in part, to a loss of the effector AvrBsT. Xp-host compatibility was further studied with the observation that a double deletion of AvrBsT and XopQ allows a host range expansion for Nicotiana benthamiana. Extensive sampling of field strains and an improved understanding of effector content will aid in efforts to design disease resistance strategies targeted against highly conserved core effectors. PMID:26089818

  9. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    SciTech Connect

    Barettin, Daniele Auf der Maur, Matthias; De Angelis, Roberta; Prosposito, Paolo; Casalboni, Mauro; Pecchia, Alessandro

    2015-03-07

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In{sub 0.48}Ga{sub 0.52 }P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k{sup →}·p{sup →} bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots.

  10. Strain Fields And Crystallographic Characteristics Of Interstitial Dislocation Loops of Various Geometry In BCC Iron

    SciTech Connect

    Sivak, Alexander B.; Chernov, Viatcheslav M.; Romanov, Vladimir A.

    2008-04-10

    The formation energy, the relaxation volume, the dipole-force tensor, the self strain tensor and strain fields of interstitial dislocation loops in bcc iron (clusters of self interstitial atoms) have been calculated by molecular statics. Hexagonal and square dislocation loops of different types with different Burgers vectors, directions of dislocation segments and habit planes containing up to {approx}2500 self-interstitials have been considered. Analytical expressions describing size dependence of the formation energy, the relaxation volume and the self strain tensor for the loops stated have been obtained. The most energetically favorable loops are hexagonal loops with Burgers vector a/2<111> and habit plane {l_brace}11x{r_brace}, where x takes values in the range from 0 to 1 depending on the loop size. The formation energy of a<100> loops with <100> and <110> dislocation segments is {approx}14% and 23% greater than that of hexagonal a/2<111> loops at N>500, respectively. The analysis of the formation energies of a/2<111> and a<100> loops demonstrated that the nucleation of an a<100> loop by joining of two a/2<111> loops is possible when the total number of constituent self-interstitials in these loops is larger than 13.

  11. Field bioassay of Metarhizium anisopliae strains to control the poultry red mite Dermanyssus gallinae.

    PubMed

    Tavassoli, M; Allymehr, M; Pourseyed, S H; Ownag, A; Bernousi, I; Mardani, K; Ghorbanzadegan, M; Shokrpoor, S

    2011-06-10

    The poultry red mite, Dermanyssus gallinae is one of the most economically deleterious ectoparasite of laying hens worldwide. To evaluate the efficacy of three strains (V245, 3247 and 715C) of entomopathogenic fungus Metarhizium anisopliae with potential as acaricides against D. gallinae, this investigation was carried out in a commercial caged laying poultry farm in Naghedeh, West Azarbaijan of Iran. The parasite infestation already existed in the farm. Sunflower oil suspension of all fungal strains, each in two concentrations (1×10(7) and 1×10(9) conidia/ml) were used separately as spray on hens and cages, and in the control group the cages were only sprayed with sunflower oil and sterile distilled water. For estimating the population rate of mites before and after treatment, special cardboard traps were fixed to cages during a 1-month period. The traps were placed on weeks -1, 0, 1, 2 and 3 and always removed after 1 w. The results showed that the population rates post fungal treatment with the lower concentration were not significantly different compared to the control group. However, the reduction in mite numbers induced by all three strains at the concentration of 1×10(9) conidia/ml was significantly higher than the control (P<0.05). The results revealed that under field conditions, higher concentrations of M. anisopliae will be required for controlling D. gallinae.

  12. Strain and deformations engineered germanene bilayer double gate-field effect transistor by first principles

    NASA Astrophysics Data System (ADS)

    Meher Abhinav, E.; Chandrasekaran, Gopalakrishnan; Kasmir Raja, S. V.

    2017-10-01

    Germanene, silicene, stanene, phosphorene and graphene are some of single atomic materials with novel properties. In this paper, we explored bilayer germanene-based Double Gate-Field Effect Transistor (DG-FET) with various strains and deformations using Density Functional Theory (DFT) and Green's approach by first-principle calculations. The DG-FET of 1.6 nm width, 6 nm channel length (Lch) and HfO2 as gate dielectric has been modeled. For intrinsic deformation of germanene bilayer, we have enforced minute mechanical deformation of wrap and twist (5°) and ripple (0.5 Å) on germanene bilayer channel material. By using NEGF formalism, I-V Characteristics of various strains and deformation tailored DG-FET was calculated. Our results show that rough edge and single vacancy (5-9) in bilayer germanene diminishes the current around 47% and 58% respectively as compared with pristine bilayer germanene. In case of strain tailored bilayer DG-FET, multiple NDR regions were observed which can be utilized in building stable multiple logic states in digital circuits and high frequency oscillators using negative resistive techniques.

  13. Biodegradation of buprofezin by Rhodococcus sp. strain YL-1 isolated from rice field soil.

    PubMed

    Li, Chao; Zhang, Ji; Wu, Zhi-Guo; Cao, Li; Yan, Xin; Li, Shun-Peng

    2012-03-14

    A buprofezin-degrading bacterium, YL-1, was isolated from rice field soil. YL-1 was identified as Rhodococcus sp. on the basis of the comparative analysis of 16S rDNA sequences. The strain could use buprofezin as the sole source of carbon and nitrogen for growth and was able to degrade 92.4% of 50 mg L(-1) buprofezin within 48 h in liquid culture. During the degradation of buprofezin, four possible metabolites, 2-tert-butylimino-3-isopropyl-1,3,5-thiadiazinan-4-one, N-tert-butyl-thioformimidic acid formylaminomethyl ester, 2-isothiocyanato-2-methyl-propane, and 2-isothiocyanato-propane, were identified using gas chromatography-mass spectrometry (GC-MS) analysis. The catechol 2,3-dioxygenase activity was strongly induced during the degradation of buprofezin. A novel microbial biodegradation pathway for buprofezin was proposed on the basis of these metabolites. The inoculation of soils treated with buprofezin with strain YL-1 resulted in a higher degradation rate than that observed in noninoculated soils, indicating that strain YL-1 has the potential to be used in the bioremediation of buprofezin-contaminated environments.

  14. Temperature and field induced strain measurements in single crystal Gd5Si2Ge2

    DOE PAGES

    McCall, S. K.; Nersessian, N.; Carman, G. P.; ...

    2016-03-29

    The first-order magneto-structural transformation that occurs in Gd5Si2Ge2 near room temperature makes it a strong candidate for many energy harvesting applications. Understanding the single crystal properties is crucial for allowing simulations of device performance. In this study, magnetically and thermally induced transformation strains were measured in a single crystal of Gd5Si2.05Ge1.95 as it transforms from a high-temperature monoclinic paramagnet to a lower-temperature orthorhombic ferromagnet. Thermally induced transformation strains of –8500 ppm, +960 ppm and +1800 ppm, and magnetically induced transformation strains of –8500 ppm, +900 ppm and +2300 ppm were measured along the a, b and c axes, respectively. Furthermore,more » using experimental data coupled with general thermodynamic considerations, a universal phase diagram was constructed showing the transition from the monoclinic to the orthorhombic phase as a function of temperature and magnetic field.« less

  15. Giant magnetic-field-induced strains in polycrystalline Ni-Mn-Ga foams

    NASA Astrophysics Data System (ADS)

    Chmielus, M.; Zhang, X. X.; Witherspoon, C.; Dunand, D. C.; Müllner, P.

    2009-11-01

    The magnetic shape-memory alloy Ni-Mn-Ga shows, in monocrystalline form, a reversible magnetic-field-induced strain (MFIS) up to 10%. This strain, which is produced by twin boundaries moving solely by internal stresses generated by magnetic anisotropy energy, can be used in actuators, sensors and energy-harvesting devices. Compared with monocrystalline Ni-Mn-Ga, fine-grained Ni-Mn-Ga is much easier to process but shows near-zero MFIS because twin boundary motion is inhibited by constraints imposed by grain boundaries. Recently, we showed that partial removal of these constraints, by introducing pores with sizes similar to grains, resulted in MFIS values of 0.12% in polycrystalline Ni-Mn-Ga foams, close to those of the best commercial magnetostrictive materials. Here, we demonstrate that introducing pores smaller than the grain size further reduces constraints and markedly increases MFIS to 2.0-8.7%. These strains, which remain stable over >200,000cycles, are much larger than those of any polycrystalline, active material.

  16. Genetic variability among Chlamydia trachomatis reference and clinical strains analyzed by pulsed-field gel electrophoresis.

    PubMed Central

    Rodriguez, P; Allardet-Servent, A; de Barbeyrac, B; Ramuz, M; Bebear, C

    1994-01-01

    Pulsed-field gel electrophoresis (PFGE) was applied to Chlamydia trachomatis reference strains representing each of the 18 serovars and to 29 clinical isolates from genital specimens collected in Bordeaux, France, or Malmö, Sweden. Comparison of the fingerprint patterns of the reference strains revealed a high level of polymorphism of the total DNA when SmaI was used (14 profiles), whereas the other enzymes, Sse8387I and ApaI, showed fewer differences. Some serovars, considered to be closely related on the basis of their antigenic determinants located on the major outer membrane protein (MOMP), such as D and Da or I and Ia, were shown to be different after PFGE of their genomic DNAs. However, serovars B and Ba and serovars L2 and L2a had identical patterns after analysis with the three endonucleases. When applied to clinical isolates, which were typed by restriction fragment length polymorphism analysis of the MOMP gene, PFGE allowed the detection of intragenotype polymorphisms and showed the identity of two strains successively isolated from the same patient. This technique seems to be an efficient tool for epidemiological studies when used in addition to serotyping or genotyping by restriction fragment length polymorphism analysis of the MOMP gene. Images PMID:7883878

  17. Survival and catabolic performance of introduced Pseudomonas strains during phytoremediation and bioaugmentation field experiment.

    PubMed

    Juhanson, Jaanis; Truu, Jaak; Heinaru, Eeva; Heinaru, Ain

    2009-12-01

    A long-term field experiment was carried out to estimate the efficiency of bioaugmentation in combination with phytoremediation for oil shale chemical industry solid waste dump area remediation. Soil samples for microbiological and chemical analysis were collected during 3 years after bacterial biomass application. Microbial communities in soil samples were analysed using both culture-based and molecular methods. The survival of the introduced bacterial strains was confirmed by cultivation-based Box-PCR genomic fingerprints and denaturing gradient gel electrophoresis fingerprinting of the 16S rRNA and lmPH genes. The introduced bacterial strains as well as corresponding catabolic genes were recovered several years after biomass application, predominantly from the rhizosphere of birches. Soil samples from bioaugmented plots showed an elevated potential for degradation of phenolic compounds even 40 months after treatment. Based on our results we can conclude that the introduced Pseudomonas strains both survived, and their metabolic traits have persisted at the contaminated site over a long period of time.

  18. Correlation-based methods in calibrating an FBG sensor with strain field non-uniformity

    NASA Astrophysics Data System (ADS)

    Cieszczyk, S.

    2015-12-01

    Fibre Bragg gratings have many sensing applications, mainly for measuring strain and temperature. The physical quantity that influences grating uniformly along its length causes a related shift of the Bragg wavelength. Many peak detection algorithms have been proposed, among which the most popular are the detection of maximum intensity, the centroid detection, the least square method, the cross-correlation, auto-correlation and fast phase correlation. Nonuniform gratings elongation is a cause of spectrum deformation. The introduction of non-uniformity can be intentional or appear as an unintended effect of placing sensing elements in the tested structure. Heterogeneous impacts on grating may result in additional errors and the difficulty in tracking the Bragg wavelength based on a distorted spectrum. This paper presents the application of correlation methods of peak wavelength shifts estimation for non-uniform Bragg grating elongation. The autocorrelation, cross-correlation and fast phase correlation algorithms are considered and experimental spectra measured for axisymmetric strain field along the Bragg grating are analyzed. The strain profile consists of constant and variable components. The results of this study indicate the properties of correlation algorithms applied to moderately non-uniform elongation of an FBG sensor.

  19. Colonization of a marker and field strain of Salmonella Enteritidis and a marker strain of Salmonella Typhimurium in vancomycin pretreated and non-pretreated laying hens

    USDA-ARS?s Scientific Manuscript database

    This study was conducted to evaluate the effects of a vancomycin pre-treatment on the ability of marker (nalidixic acid-resistant) S. Enteritidis (SE-M), field S. Enteritidis (SE-F), and marker S. Typhimurium (ST-M) strains to colonize within the intestinal and reproductive tracts and translocate to...

  20. Electric-field control of magnetism via strain transfer across ferromagnetic/ferroelectric interfaces.

    PubMed

    Taniyama, Tomoyasu

    2015-12-23

    By taking advantage of the coupling between magnetism and ferroelectricity, ferromagnetic (FM)/ferroelectric (FE) multiferroic interfaces play a pivotal role in manipulating magnetism by electric fields. Integrating the multiferroic heterostructures into spintronic devices significantly reduces energy dissipation from Joule heating because only an electric field is required to switch the magnetic element. New concepts of storage and processing of information thus can be envisioned when the electric-field control of magnetism is a viable alternative to the traditional current based means of controlling magnetism. This article reviews some salient aspects of the electric-field effects on magnetism, providing a short overview of the mechanisms of magneto-electric (ME) coupling at the FM/FE interfaces. A particular emphasis is placed on the ME effect via interfacial magneto-elastic coupling arising from strain transfer from the FE to FM layer. Recent results that demonstrate the electric-field control of magnetic anisotropy, magnetic order, magnetic domain wall motion, and etc are described. Obstacles that need to be overcome are also discussed for making this a reality for future device applications.

  1. Strain field of the monovacancy in silicene: First-principles study

    SciTech Connect

    Li, Rui Liu, Zhongli; Ma, Wenqiang; Tan, Yonggang

    2016-05-15

    The in-plane strain fields of single-vacancy silicene with different monovacancy (MV) concentrations, as well as the corresponding electronic band structures, are investigated by using the first-principle calculations. Firstly the self-healing MV is found to be the most stable ground structure in silicene, which is different from the other 2D hexagonal honeycomb materials, e.g. graphene, h-BN. In the isolated MV center, the bonds along the pentagons are compressed, creating a compress field, and those close to the distorted hexagons are stretched, creating a stretch field. As the MV concentration increasing, the interacted compress field tends to corrugate the defected silicene, while the interacted stretch field impacts little on the low-buckled structure. Especially, the corrugation presents in those supercells with small MV concentration, just as the (4, 5), (4, 6), (4, 7), (4, 8) supercells. The corrugations approach zero at both low and high MV concentrations, and the (4, 6) supercell with a MV concentration of about 0.021, has a peak value of 3.23Å. The electronic calculations show that the linear dispersion at Γ point in pristine silicene is broken by the lower lattice symmetry of the self-healing MV reconstruction, which translates it into metal as well.

  2. Strain field of the monovacancy in silicene: First-principles study

    NASA Astrophysics Data System (ADS)

    Li, Rui; Liu, Zhongli; Ma, Wenqiang; Tan, Yonggang

    2016-05-01

    The in-plane strain fields of single-vacancy silicene with different monovacancy (MV) concentrations, as well as the corresponding electronic band structures, are investigated by using the first-principle calculations. Firstly the self-healing MV is found to be the most stable ground structure in silicene, which is different from the other 2D hexagonal honeycomb materials, e.g. graphene, h-BN. In the isolated MV center, the bonds along the pentagons are compressed, creating a compress field, and those close to the distorted hexagons are stretched, creating a stretch field. As the MV concentration increasing, the interacted compress field tends to corrugate the defected silicene, while the interacted stretch field impacts little on the low-buckled structure. Especially, the corrugation presents in those supercells with small MV concentration, just as the (4, 5), (4, 6), (4, 7), (4, 8) supercells. The corrugations approach zero at both low and high MV concentrations, and the (4, 6) supercell with a MV concentration of about 0.021, has a peak value of 3.23Å. The electronic calculations show that the linear dispersion at Γ point in pristine silicene is broken by the lower lattice symmetry of the self-healing MV reconstruction, which translates it into metal as well.

  3. Isolation of an attenuated myxoma virus field strain that can confer protection against myxomatosis on contacts of vaccinates.

    PubMed

    Bárcena, J; Pagès-Manté, A; March, R; Morales, M; Ramírez, M A; Sánchez-Vizcaíno, J M; Torres, J M

    2000-01-01

    Twenty MV strains obtained from a survey of field strains currently circulating throughout Spain were analyzed for their virulence and horizontal spreading among rabbits by contact transmission. A virus strain with suitable characteristics to be used as a potential vaccine against myxomatosis in wild rabbit populations was selected. Following inoculation, the selected MV strain elicited high levels of MV specific antibodies and induced protection of rabbits against a virulent MV challenge. Furthermore, the attenuated MV was transmitted to 9 out of 16 uninoculated rabbits by contact, inducing protection against myxomatosis.

  4. 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.

  5. 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.

  6. Fractional quantum Hall effect in strained graphene: Stability of Laughlin states in disordered pseudomagnetic fields

    NASA Astrophysics Data System (ADS)

    Bagrov, Andrey A.; Principi, Alessandro; Katsnelson, Mikhail I.

    2017-03-01

    We address the question of the stability of the fractional quantum Hall effect in the presence of pseudomagnetic disorder generated by mechanical deformations of a graphene sheet. Neglecting the potential disorder and taking into account only strain-induced random pseudomagnetic fields, it is possible to write down a Laughlin-like trial ground-state wave function explicitly. Exploiting the Laughlin plasma analogy, we demonstrate that in the case of fluctuating pseudomagnetic fluxes of a relatively small amplitude, the fractional quantum Hall effect is always stable upon the deformations. By contrast, in the case of bubble-induced pseudomagnetic fields in graphene on a substrate (a small number of large fluxes) the disorder can be strong enough to cause a glass transition in the corresponding classical Coulomb plasma, resulting in the destruction of the fractional quantum Hall regime and in a quantum phase transition to a nonergodic state of the lowest Landau level.

  7. Amphidial structure of ivermectin-resistant and susceptible laboratory and field strains of Haemonchus contortus.

    PubMed

    Freeman, Andrea S; Nghiem, Catherine; Li, Jian; Ashton, Francis T; Guerrero, Jorge; Shoop, Wesley L; Schad, Gerhard A

    2003-01-02

    The development of anthelmintic resistance by nematode parasites is a growing problem for veterinarians, pet owners, and producers. The intensive use of the macrocyclic lactones for the treatment of a variety of parasitic diseases has hastened the development of resistance to this family of parasiticides. As a result, resistance to ivermectin, moxidectin, nemadectin, and doramectin by Haemonchus contortus has been documented throughout the world. Sensory neurons located in the cephalic end of nematodes are in close contact with the external environment. Through these neurons, important chemical and thermal cues are gathered by the parasite. Examination of serial electron micrographs of ivermectin-susceptible and ivermectin-resistant H. contortus allows for comparison of neuronal structure, arrangement of neurons within the amphidial channel, and distance of the tip of the dendritic processes to the amphidial pore. The latter of these characteristics provides a useful means by which to compare the association between the neurons and the external environment of the worm. Comparison of parental laboratory strains of ivermectin-susceptible strains of H. contortus with related selected, ivermectin-resistant strains and with a wild-type ivermectin-susceptible field strain of H. contortus from Louisiana reveal that the ivermectin-resistant worms examined have markedly shorter sensory cilia than their ivermectin-susceptible parental counterparts. Additionally, the amphidial neurons of ivermectin-resistant worms are characterized by generalized degeneration and loss of detail, whereas other neurons outside of the channels, such as the labial and cephalic neurons, are normal in structure. These findings raise a number of questions regarding the relationship between amphidial structure and ivermectin resistance as well as the role of amphids as a means of entry for ivermectin. While shortened amphidial sensilla are associated with ivermectin resistance, it remains unclear if

  8. Phase field approach with anisotropic interface energy and interface stresses: Large strain formulation

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; Warren, James A.

    2016-06-01

    A thermodynamically consistent, large-strain, multi-phase field approach (with consequent interface stresses) is generalized for the case with anisotropic interface (gradient) energy (e.g. an energy density that depends both on the magnitude and direction of the gradients in the phase fields). Such a generalization, if done in the "usual" manner, yields a theory that can be shown to be manifestly unphysical. These theories consider the gradient energy as anisotropic in the deformed configuration, and, due to this supposition, several fundamental contradictions arise. First, the Cauchy stress tensor is non-symmetric and, consequently, violates the moment of momentum principle, in essence the Herring (thermodynamic) torque is imparting an unphysical angular momentum to the system. In addition, this non-symmetric stress implies a violation of the principle of material objectivity. These problems in the formulation can be resolved by insisting that the gradient energy is an isotropic function of the gradient of the order parameters in the deformed configuration, but depends on the direction of the gradient of the order parameters (is anisotropic) in the undeformed configuration. We find that for a propagating nonequilibrium interface, the structural part of the interfacial Cauchy stress is symmetric and reduces to a biaxial tension with the magnitude equal to the temperature- and orientation-dependent interface energy. Ginzburg-Landau equations for the evolution of the order parameters and temperature evolution equation, as well as the boundary conditions for the order parameters are derived. Small strain simplifications are presented. Remarkably, this anisotropy yields a first order correction in the Ginzburg-Landau equation for small strains, which has been neglected in prior works. The next strain-related term is third order. For concreteness, specific orientation dependencies of the gradient energy coefficients are examined, using published molecular dynamics

  9. Microbial field pilot study. Final report

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Coates, J.D.; Chisholm, J.L.

    1993-05-01

    A multi-well microbially enhanced oil recovery field pilot has been performed in the Southeast Vassar Vertz Sand Unit in Payne County, Oklahoma. The primary emphasis of the experiment was preferential plugging of high permeability zones for the purpose of improving waterflood sweep efficiency. Studies were performed to determine reservoir chemistry, ecology, and indigenous bacteria populations. Growth experiments were used to select a nutrient system compatible with the reservoir that encouraged growth of a group of indigenous nitrate-using bacteria and inhibit growth of sulfate-reducing bacteria. A specific field pilot area behind an active line drive waterflood was selected. Surface facilities were designed and installed. Injection protocols of bulk nutrient materials were prepared to facilitate uniform distribution of nutrients within the pilot area. By the end of December, 1991, 82.5 tons (75.0 tonnes) of nutrients had been injected in the field. A tracer test identified significant heterogeneity in the SEVVSU and made it necessary to monitor additional production wells in the field. The tracer tests and changes in production behavior indicate the additional production wells monitored during the field trial were also affected. Eighty two and one half barrels (13.1 m{sup 3}) of tertiary oil have been recovered. Microbial activity has increased CO{sub 2} content as indicated by increased alkalinity. A temporary rise in sulfide concentration was experienced. These indicate an active microbial community was generated in the field by the nutrient injection. Pilot area interwell pressure interference test results showed that significant permeability reduction occurred. The interwell permeabilities in the pilot area between the injector and the three pilot production wells were made more uniform which indicates a successful preferential plugging enhanced oil recovery project.

  10. Severe Congenital Toxoplasmosis: A Case Report and Strain Characterization

    PubMed Central

    Sarkari, Bahador; Abdolahi Khabisi, Samaneh

    2015-01-01

    We report a fatal congenital toxoplasmosis case in an Iranian woman in the south of Iran. A pregnant mother had been admitted at the 15th week of her pregnancy on account of a febrile illness, symptoms of common cold, and enlargement of submandibular lymph nodes. Serological testing of the mother's serum revealed positive IgG and IgM anti-Toxoplasma antibodies. Amniotic fluid was taken and evaluated by polymerase chain reaction (PCR) assay with a direct amplification of the Toxoplasma URPT gene which was found to be positive. Sequencing and analysis of PCR product revealed that the isolate has the most similarity with type I of Toxoplasma gondii. Fetal scan showed anomaly in fetus including mild hydrocephaly. Termination of the pregnancy was suggested by the physician and pregnancy was terminated 178 days after conception. PMID:25685568

  11. Higher Drop in Speed during a Repeated Sprint Test in Soccer Players Reporting Former Hamstring Strain Injury.

    PubMed

    Røksund, Ola D; Kristoffersen, Morten; Bogen, Bård E; Wisnes, Alexander; Engeseth, Merete S; Nilsen, Ann-Kristin; Iversen, Vegard V; Mæland, Silje; Gundersen, Hilde

    2017-01-01

    Aim: Hamstring strain injury is common in soccer. The aim of this study was to evaluate the physical capacity of players who have and have not suffered from hamstring strain injury in a sample of semi-professional and professional Norwegian soccer players in order to evaluate characteristics and to identify possible indications of insufficient rehabilitation. Method: Seventy-five semi-professional and professional soccer players (19 ± 3 years) playing at the second and third level in the Norwegian league participated in the study. All players answered a questionnaire, including one question about hamstring strain injury (yes/no) during the previous 2 years. They also performed a 40 m maximal sprint test, a repeated sprint test (8 × 20 m), a countermovement jump, a maximal oxygen consumption (VO2max) test, strength tests and flexibility tests. Independent sample t-tests were used to evaluate differences in the physical capacity of the players who had suffered from hamstring strain injury and those who had not. Mixed between-within subject's analyses of variance was used to compare changes in speed during the repeated sprint test between groups. Results: Players who reported hamstring strain injury during the previous two years (16%) had a significantly higher drop in speed (0.07 vs. 0.02 s, p = 0.007) during the repeated sprint test, compared to players reporting no previous hamstring strain injury. In addition, there was a significant interaction (groups × time) (F = 3.22, p = 0.002), showing that speed in the two groups changed differently during the repeated sprint test. There were no significant differences in relations to age, weight, height, body fat, linear speed, countermovement jump height, leg strength, VO2max, or hamstring flexibility between the groups. Conclusion: Soccer players who reported hamstring strain injury during the previous 2 years showed significant higher drop in speed during the repeated sprint test compared to players with no hamstring

  12. Higher Drop in Speed during a Repeated Sprint Test in Soccer Players Reporting Former Hamstring Strain Injury

    PubMed Central

    Røksund, Ola D.; Kristoffersen, Morten; Bogen, Bård E.; Wisnes, Alexander; Engeseth, Merete S.; Nilsen, Ann-Kristin; Iversen, Vegard V.; Mæland, Silje; Gundersen, Hilde

    2017-01-01

    Aim: Hamstring strain injury is common in soccer. The aim of this study was to evaluate the physical capacity of players who have and have not suffered from hamstring strain injury in a sample of semi-professional and professional Norwegian soccer players in order to evaluate characteristics and to identify possible indications of insufficient rehabilitation. Method: Seventy-five semi-professional and professional soccer players (19 ± 3 years) playing at the second and third level in the Norwegian league participated in the study. All players answered a questionnaire, including one question about hamstring strain injury (yes/no) during the previous 2 years. They also performed a 40 m maximal sprint test, a repeated sprint test (8 × 20 m), a countermovement jump, a maximal oxygen consumption (VO2max) test, strength tests and flexibility tests. Independent sample t-tests were used to evaluate differences in the physical capacity of the players who had suffered from hamstring strain injury and those who had not. Mixed between-within subject's analyses of variance was used to compare changes in speed during the repeated sprint test between groups. Results: Players who reported hamstring strain injury during the previous two years (16%) had a significantly higher drop in speed (0.07 vs. 0.02 s, p = 0.007) during the repeated sprint test, compared to players reporting no previous hamstring strain injury. In addition, there was a significant interaction (groups × time) (F = 3.22, p = 0.002), showing that speed in the two groups changed differently during the repeated sprint test. There were no significant differences in relations to age, weight, height, body fat, linear speed, countermovement jump height, leg strength, VO2max, or hamstring flexibility between the groups. Conclusion: Soccer players who reported hamstring strain injury during the previous 2 years showed significant higher drop in speed during the repeated sprint test compared to players with no hamstring

  13. Reliability of photovoltaic systems: A field report

    NASA Astrophysics Data System (ADS)

    Thomas, M. G.; Fuentes, M. K.; Lashway, C.; Black, B. D.

    Performance studies and field measurements of photovoltaic systems indicate a 1 to 2% per year degradation in array energy production. The cause for much of the degradation has been identified as soiling, failed modules, and failures in interconnections. System performance evaluation continues to be complicated by the poor reliability of some power conditioning hardware that has greatly diminished the system availability and by inconsistent field ratings. Nevertheless, the current system reliability is consistent with degradation of less than 10% in 5 years and with estimates of less than 10% per year of the energy value for O and M.

  14. Reliability of photovoltaic systems - A field report

    NASA Astrophysics Data System (ADS)

    Thomas, M. G.; Fuentes, M. K.; Lashway, C.; Black, B. D.

    Performance studies and field measurements of photovoltaic systems indicate a 1-2-percent/yr degradation in array energy production. The cause for much of the degradation has been identified as soiling, failed modules, and failures in interconnections. System performance evaluation continues to be complicated by the poor reliability of some power conditioning hardware (which greatly diminished system availability) and by inconsistent field ratings. Nevertheless, the current system reliability is consistent with degradation of less than 10 percent in 5 years and with estimates of less than 10 percent/yr of the energy value for O&M.

  15. Strain-induced modulation on phonon and electronic properties of suspended black phosphorus field effect transistor

    NASA Astrophysics Data System (ADS)

    Zheng, Bo; Si, Naichao; Xie, Guoxin; Wang, Quan

    2017-02-01

    Black phosphorus has recently appeared as a promising two-dimensional material for applications in high performance nanoelectronics. Its single- and few-atomic layer forms in field-effect transistors have attracted a lot of attention due to the tunable bandgap (0.3-2.0 eV), high carrier mobility (1000 cm2 V-1 s-1) and decent on-off ratios (105). Here, we demonstrate a suspended black phosphorus field effect transistor (BP-FET) and utilize Raman spectroscope to characterize the strain on the effects of Raman phonon. We find that red shifts appear in all the three vibrational modes (Ag1 , B2g and Ag2) in different degrees. Among them, Ag1 mode is most sensitive to the tensile strain. We further investigate the electronic properties with a Cascade semi-automatic probe station. The linear relationships in the output curves indicate the contacts between black phosphorus and electrodes are ohmic contacts. The transfer characteristic curves declare the drain current modulation is ∼ 7.6 ×103 for the hole conduction and ∼57 for the electron conduction. Mobility of this device is found to be 347.5 cm2 V-1 s-1 and 4.9 cm2 V-1 s-1 for the hole and electron conduction, respectively. These results provide a theoretical basis for the coordination of high-performance black phosphorus electronic components.

  16. Studies of Ultrafast Femtosecond-Laser-Generated Strain Fields with Coherent X-rays

    SciTech Connect

    Dufresne, Eric M.; Adams, Bernhard; Landahl, Eric C.; Khounsary, Ali M.; Reis, David; Fritz, David M.; Lee, SooHeyong

    2007-01-19

    In its 324 bunch-mode of operation, the Advanced Photon Source (APS) has opened new avenues of femtosecond-laser science and techniques. In this new mode, if one uses the tightly focused low-pulse energy (nJ), high repetition rate fs-laser Ti:sapphire oscillator (88 MHz) on beamline 7ID, every laser pulse and X-ray bunch can be overlapped and delayed with respect to each other, resulting in a high-repetition rate pump-probe experiment that uses all the APS X-ray bunches. This paper describes an example of how coherent X-ray experiments may be used to study laser-generated strain fields in semiconductors. With an oscillator beam focused to 6 {mu}m onto GaAs, we have observed coherent X-ray diffraction patterns with a high-resolution camera. We have developed two techniques to observe the strain field, a topographic technique and a coherent diffraction technique. The topographic technique is quite useful to achieve a coarse spatial overlap of the the laser and X-ray beams. The coherent X-ray technique allows one to push the alignment to a few microns. This paper focuses solely on the latter technique. This experiment may help to develop techniques that will be used at the future free electron laser sources, where coherent and pump-probe experiments can be done simultaneously.

  17. Small strain multiphase-field model accounting for configurational forces and mechanical jump conditions

    NASA Astrophysics Data System (ADS)

    Schneider, Daniel; Schoof, Ephraim; Tschukin, Oleg; Reiter, Andreas; Herrmann, Christoph; Schwab, Felix; Selzer, Michael; Nestler, Britta

    2017-08-01

    Computational models based on the phase-field method have become an essential tool in material science and physics in order to investigate materials with complex microstructures. The models typically operate on a mesoscopic length scale resolving structural changes of the material and provide valuable information about the evolution of microstructures and mechanical property relations. For many interesting and important phenomena, such as martensitic phase transformation, mechanical driving forces play an important role in the evolution of microstructures. In order to investigate such physical processes, an accurate calculation of the stresses and the strain energy in the transition region is indispensable. We recall a multiphase-field elasticity model based on the force balance and the Hadamard jump condition at the interface. We show the quantitative characteristics of the model by comparing the stresses, strains and configurational forces with theoretical predictions in two-phase cases and with results from sharp interface calculations in a multiphase case. As an application, we choose the martensitic phase transformation process in multigrain systems and demonstrate the influence of the local homogenization scheme within the transition regions on the resulting microstructures.

  18. CO-CO coupling on Cu facets: Coverage, strain and field effects

    DOE PAGES

    Sandberg, Robert B.; Montoya, Joseph H.; Chan, Karen; ...

    2016-08-21

    We present a DFT study on the effect of coverage, strain, and electric field on CO-CO coupling energetics on Cu (100), (111), and (211). Our calculations indicate that CO-CO coupling is facile on all three facets in the presence of a cation-induced electric field in the Helmholtz plane, with the lowest barrier on Cu(100). The CO dimerization pathway is therefore expected to play a role in C2 formation at potentials negative of the Cu potential of zero charge, corresponding to CO2/CO reduction conditions at high pH. Both increased *CO coverage and tensile strain further improve C-C coupling energetics on Cumore » (111) and (211). Since CO dimerization is facile on all 3 Cu facets, subsequent surface hydrogenation steps may also play an important role in determining the overall activity towards C2 products. Adsorption of *CO, *H, and *OH on the 3 facets were investigated with a Pourbaix analysis. Here, the (211) facet has the largest propensity to co-adsorb *CO and *H, which would favor surface hydrogenation following CO dimerization.« less

  19. CO-CO coupling on Cu facets: Coverage, strain and field effects

    SciTech Connect

    Sandberg, Robert B.; Montoya, Joseph H.; Chan, Karen; Nørskov, Jens K.

    2016-08-21

    We present a DFT study on the effect of coverage, strain, and electric field on CO-CO coupling energetics on Cu (100), (111), and (211). Our calculations indicate that CO-CO coupling is facile on all three facets in the presence of a cation-induced electric field in the Helmholtz plane, with the lowest barrier on Cu(100). The CO dimerization pathway is therefore expected to play a role in C2 formation at potentials negative of the Cu potential of zero charge, corresponding to CO2/CO reduction conditions at high pH. Both increased *CO coverage and tensile strain further improve C-C coupling energetics on Cu (111) and (211). Since CO dimerization is facile on all 3 Cu facets, subsequent surface hydrogenation steps may also play an important role in determining the overall activity towards C2 products. Adsorption of *CO, *H, and *OH on the 3 facets were investigated with a Pourbaix analysis. Here, the (211) facet has the largest propensity to co-adsorb *CO and *H, which would favor surface hydrogenation following CO dimerization.

  20. CO-CO coupling on Cu facets: Coverage, strain and field effects

    NASA Astrophysics Data System (ADS)

    Sandberg, Robert B.; Montoya, Joseph H.; Chan, Karen; Nørskov, Jens K.

    2016-12-01

    We present a DFT study on the effect of coverage, strain, and electric field on CO-CO coupling energetics on Cu (100), (111), and (211). Our calculations indicate that CO-CO coupling is facile on all three facets in the presence of a cation-induced electric field in the Helmholtz plane, with the lowest barrier on Cu(100). The CO dimerization pathway is therefore expected to play a role in C2 formation at potentials negative of the Cu potential of zero charge, corresponding to CO2/CO reduction conditions at high pH. Both increased *CO coverage and tensile strain further improve C-C coupling energetics on Cu (111) and (211). Since CO dimerization is facile on all 3 Cu facets, subsequent surface hydrogenation steps may also play an important role in determining the overall activity towards C2 products. Adsorption of *CO, *H, and *OH on the 3 facets were investigated with a Pourbaix analysis. The (211) facet has the largest propensity to co-adsorb *CO and *H, which would favor surface hydrogenation following CO dimerization.

  1. Determination of strain fields in porous shape memory alloys using micro-computed tomography

    NASA Astrophysics Data System (ADS)

    Bormann, Therese; Friess, Sebastian; de Wild, Michael; Schumacher, Ralf; Schulz, Georg; Müller, Bert

    2010-09-01

    Shape memory alloys (SMAs) belong to 'intelligent' materials since the metal alloy can change its macroscopic shape as the result of the temperature-induced, reversible martensite-austenite phase transition. SMAs are often applied for medical applications such as stents, hinge-less instruments, artificial muscles, and dental braces. Rapid prototyping techniques, including selective laser melting (SLM), allow fabricating complex porous SMA microstructures. In the present study, the macroscopic shape changes of the SMA test structures fabricated by SLM have been investigated by means of micro computed tomography (μCT). For this purpose, the SMA structures are placed into the heating stage of the μCT system SkyScan 1172™ (SkyScan, Kontich, Belgium) to acquire three-dimensional datasets above and below the transition temperature, i.e. at room temperature and at about 80°C, respectively. The two datasets were registered on the basis of an affine registration algorithm with nine independent parameters - three for the translation, three for the rotation and three for the scaling in orthogonal directions. Essentially, the scaling parameters characterize the macroscopic deformation of the SMA structure of interest. Furthermore, applying the non-rigid registration algorithm, the three-dimensional strain field of the SMA structure on the micrometer scale comes to light. The strain fields obtained will serve for the optimization of the SLM-process and, more important, of the design of the complex shaped SMA structures for tissue engineering and medical implants.

  2. Quantitative determination of strain fields around Ni{sub 4}Ti{sub 3} precipitates in NiTi

    SciTech Connect

    Tirry, W. . E-mail: wim.tirry@ua.ac.be; Schryvers, D.

    2005-02-01

    High-resolution transmission electron microscopy and image-processing techniques are used to measure the strain fields surrounding coherent Ni{sub 4}Ti{sub 3} precipitates in an austenitic Ni{sub 51}Ti{sub 49} matrix. Images are recorded in the [111-bar ]{sub B2} and the [101-bar ]{sub B2} zones, and the (110){sub B2} interplanar spacings are used to determine the strain induced by both small (50 nm diameter) and large (300 nm diameter) precipitates. From these observations, the maximum strain in the surrounding matrix is mapped and identified as compressive or tensile. Interactions between strain fields of different precipitates are also investigated. A simple model for the observed strain is proposed and compared to the classical Eshelby solution for an ellipsoidal inclusion.

  3. Biochemical studies on different field strains of the pink bollworm Pectinophora gossypiella (Saund.) (Lepidoptera: Gelechiidae) in Egypt.

    PubMed

    Massoud, M A; Mourad, A K; El, Beltagy A; El, Salamony M E

    2006-01-01

    The specific activity of the esterases and the corresponding total proteins of the diapaused pink bollworm, Pectinophora gossypiella larvae taken from dry bolls which had been left in the cotton fields of the growing seasons of 2000&2001 were measured in four field strains representing the four Governorates: Alexandria, Al-Behaira , Kafr El-Shaikh, and Al-Gharbia. Parallel to these larvae the last generation of the pink bollworm moths trapped from Al-Behaira fields at the end of the same seasons were included in the comparative study. Besides, the susceptible strain larvae and moths from the Lab. of Bollworms Department at the Institute of Plant Protection, Cairo were used as a reference for comparing levels of resistance in the four bollworm strains representing the four Governorates and its impact on proteins and esterases types and activity. Gel scanning with respective standard molecular weights revealed variation in protein bands number and molecular weight type among the four tested field strains. Similarly, the sites of esterases on the SDS-PAGE proved high level of resistance reflected in appearance of isozymes, especially in Al-Gharbia field strain. Generally, Alexandria field strain showed the least level of resistance due to the limited area of cotton fields and the less use of insecticides in Alexandria fields. It is suggested that SDS-PAGE technique can be a biomarker for detection of susceptibility levels or resistance in the field strains, which should lead to a change in the currently applied chemicals. All field strains which had exposed annually to successive insecticide applications revealed an increase of protein bands and a decrease of esterases of lower molecular weight than those in the susceptible strain. Chemical insecticides are known to be able to act as inducers for the biosynthesis of cellular proteins or as inhibitors of enzymes; so, the molecular biochemical explanation of variations among the tested field strains can be attributed to

  4. Methane Emissions from Rice Fields - Final Report

    SciTech Connect

    Khalil, M. Aslam; Rasmussen,Reinhold A.

    2002-12-03

    Methane (Ch4) is a greenhouse gas regarded second only to carbon dioxide in its ability to cause global warming. Methane is important because of its relatively fast increase, and also because it is, per molecule, some 60 times more effective than carbon dioxide in causing global warming. The largest present anthropogenic sources of methane are rice fields, cattle and biomass burning.

  5. Most effective way to improve the hydrogen storage abilities of Na-decorated BN sheets: applying external biaxial strain and an electric field.

    PubMed

    Tang, Chunmei; Zhang, Xue; Zhou, Xiaofeng

    2017-02-15

    Density functional calculations were used to investigate the hydrogen storage abilities of Na-atoms-decorated BN sheets under both external biaxial strain and a vertical electric field. The Na atom generally has the weakest binding strength to a given substrate compared with the other elements in the periodic table [PANS, 2016, 113, 3735]. Consequently, it is understudied in comparison to other elements and there are few reports about the hydrogen storage abilities of Na-decorated nanomaterials. We calculated that the average binding energy (Eb) of Na atoms to the pure BN sheet is 1.08 eV, which is smaller than the cohesive energy of bulk Na (1.11 eV). However, the Eb can be increased to 1.15 eV under 15% biaxial strain, and further up to 1.53 eV with the control of both 15% biaxial strain and a 5.14 V nm(-1) electric field (E-field). Therefore, the application of biaxial strain and an external upward E-field can prevent clustering of the Na atoms on the surface of a BN sheet, which is crucial for the hydrogen storage. Each Na atom on the surface of a BN sheet can adsorb only one H2 molecule when no strain or E-field is applied; however, the absorption increases to five H2 molecules under 15% biaxial strain and six H2 molecules under both 15% biaxial strain combined with a 5.14 V nm(-1)E-field. The average adsorption energies for H2 of BN-(Na-mH2) (m = 1-6) are within the range of practical applications (0.2-0.6 eV). The hydrogen gravimetric density of the periodic BN-(Na-6H2)4 structure is 9 wt%, which exceeds the 5.5 wt% value that should be met by 2017 as specified by the US Department of Energy. On the other side, removal of the biaxial strain and E-field can help to desorb the H2 molecule. These findings suggest a new route to design hydrogen storage materials under near-ambient conditions.

  6. Direct synchrotron x-ray measurements of local strain fields in elastically and plastically bent metallic glasses

    DOE PAGES

    Wu, Yuan; Stoica, Alexandru Dan; Ren, Yang; ...

    2015-09-03

    In situ high-energy synchrotron X-ray diffraction was conducted on elastically and plastically bent bulk metallic glass (BMG) thin plates, from which distinct local elastic strain fields were mapped spatially. These directly measured residual strain fields can be nicely interpreted by our stress analysis, and also validate a previously proposed indirect residual-stress-measurement method by relating nanoindentation hardness to residual stresses. Local shear strain variations on the cross sections of these thin plates were found in the plastically bent BMG, which however cannot be determined from the indirect indentation method. As a result, this study has important implications in designing and manipulatingmore » internal strain fields in BMGs for the purpose of ductility enhancement.« less

  7. Direct synchrotron x-ray measurements of local strain fields in elastically and plastically bent metallic glasses

    SciTech Connect

    Wu, Yuan; Stoica, Alexandru Dan; Ren, Yang; Ma, Dong; Gao, Yanfei F.; Bei, Hongbin

    2015-09-03

    In situ high-energy synchrotron X-ray diffraction was conducted on elastically and plastically bent bulk metallic glass (BMG) thin plates, from which distinct local elastic strain fields were mapped spatially. These directly measured residual strain fields can be nicely interpreted by our stress analysis, and also validate a previously proposed indirect residual-stress-measurement method by relating nanoindentation hardness to residual stresses. Local shear strain variations on the cross sections of these thin plates were found in the plastically bent BMG, which however cannot be determined from the indirect indentation method. As a result, this study has important implications in designing and manipulating internal strain fields in BMGs for the purpose of ductility enhancement.

  8. Laser range pole field evaluation report

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A field evaluation was made of the laser pole equipment. The basic plan for the evaluation was to expose the equipment to the actual people and environment for which it was intended and determine, through the use of the equipment, its resultant effectivity in terms of improved performance. Results show the equipment performed better than expected in the high elevation clean air of Colorado, and did as well in Tennessee.

  9. Complete genome sequence of the biofilm-forming Microbacterium sp. strain BH-3-3-3, isolated from conventional field-grown lettuce (Lactuca sativa) in Norway.

    PubMed

    Dees, Merete Wiken; Brurberg, May Bente; Lysøe, Erik

    2017-03-01

    The genus Microbacterium contains bacteria that are ubiquitously distributed in various environments and includes plant-associated bacteria that are able to colonize tissue of agricultural crop plants. Here, we report the 3,508,491 bp complete genome sequence of Microbacterium sp. strain BH-3-3-3, isolated from conventionally grown lettuce (Lactuca sativa) from a field in Vestfold, Norway. The nucleotide sequence of this genome was deposited into NCBI GenBank under the accession CP017674.

  10. Termiticide field test report: New termiticides & emerging technologies

    Treesearch

    Bradford M. Kard

    2000-01-01

    Testing at our nationwide field sites detemines the years-of-effectiveness of currently marketed and potentially new termiticides as treatments to soil under long-term field conditions. Several new termiticide candidates and formulations have been placed in the field during the past four years and will be reported on after they complete five years of testing.

  11. Magnetic-Field-Induced Strain of Shape-Memory Alloy Fe3Pt Studied by a Capacitance Method in a Pulsed Magnetic Field

    NASA Astrophysics Data System (ADS)

    Sakon, Takuo; Takaha, Atsuo; Obara, Kenji; Dejima, Koutatsu; Nojiri, Hiroyuki; Motokawa, Mitsuhiro; Fukuda, Takashi; Kakeshita, Tomoyuki

    2007-01-01

    The precise magnetic-field-induced strain (MFIS) and magnetization of the martensite metallic compound Fe3Pt in a martensitic phase were studied in a pulsed magnetic field using the capacitance method at low temperatures down to 4.2 K, which is much lower than the martensitic transformation temperature TM=85 K. After zero field cooling, a pulsed magnetic field with a maximum frequency of 160 Hz was applied parallel to the [001]p axis. A large MFIS was measured. The value of the MFIS is Δ L/L=-1.7%. When the magnetic field was decreased, the recovery of the strain was observed. In the second applied field, a strain of about 0.6% was observed. This means that MFIS occurs even in short-pulse magnetic fields. MFIS was observed below 70 K. The largest strain was observed at 20 K. These results are almost the same as the MFIS in a steady magnetic field using a superconducting magnet.

  12. RMDF leach-field decontamination. Final report

    SciTech Connect

    Carroll, J W; Marzec, J M; Stelle, A M

    1982-09-15

    The objective of the decontamination effort was to place the Radioactive Materials Disposal Facility (RMDF) leach field in a condition suitable for release for unrestricted use. Radioactively contaminated soil was excavated from the leach field to produce a condition of contamination as low as reasonably achievable (ALARA). The contaminated soil was boxed and shipped to an NRC-licensed burial site at Beatty, Nevada, and to the DOE burial site at Hanford, Washington. The soil excavation project successfully reduced the contamination level in the leach field to background levels, except for less than 0.6 mCi of Sr-90 and trace amounts of Cs-137 that are isolated in cracks in the bedrock. The cracks are greater than 10 ft below the surface and have been sealed with a bituminous asphalt mastic. A pathways analysis for radiation exposure to humans from the remaining radionuclides was performed, assuming intensive home gardening, and the results show that the total first year whole body dose equivalent would be about 0.1 mrem/year. This dose equivalent is a projection for the hypothetical ingestion of vegetables grown on the site. Assuming that an average adult consumes 64 kg of green leafy vegetables per year and that the entire yearly supply could be grown on the site, the amount of ingested Sr-90 and Cs-137 is calculated to be 1100 pCi/year and 200 pCi/year. This ingested quantity would produce a total first year whole body dose equivalent of 0.10 mrem, using the accepted soil-to-plant transfer factors of 0.0172 and 0.010 for Sr-90 and Cs-137, respectively. The whole body dose equivalent exposure value of 0.1 mrem/year is far below the tentative limit established by NRC of 5 mrem/year for areas released for unrestricted use.

  13. Finite Element Analysis of Cross Rolling on AISI 304 Stainless Steel: Prediction of Stress and Strain Fields

    NASA Astrophysics Data System (ADS)

    Rout, Matruprasad; Pal, Surjya Kanta; Singh, Shiv Brat

    2017-02-01

    Studies on the effect of strain path during rolling has been carried out for a long time, but the same has not been done using Finite Element Analysis (FEA). Change in strain path affects the state variables in the rolled plate like stress, strain, temperature etc. In the current work, Finite Element Analysis for cross rolling of AISI 304 austenitic stainless steel has been carried out by rotating the plate by 90° in between the passes. To analyze stress and strain fields in the material for cross rolling, a full 3D model of work-roll and plate has been developed using rigid-viscoplastic finite element method. The stress and strain fields, considering von-Mises yield criteria, are calculated by using updated Lagrangian method. In addition to these, the model also calculates the normal pressure and strain rate distribution in the plate during cross rolling. The nature of the variations of stress and strain fields in the plate, predicted by the model, is in good agreement with the previously published works for unidirectional rolling.

  14. Genetics, cross-resistance and mechanism of resistance to spinosad in a field strain of Musca domestica L. (Diptera: Muscidae).

    PubMed

    Khan, Hafiz Azhar Ali; Akram, Waseem; Shad, Sarfraz Ali

    2014-02-01

    The house fly, Musca domestica L., is a cosmopolitan insect with the ability to develop resistance to insecticides used for their management. In the present study, we investigated the genetics of spinosad resistance, and cross-resistance potential to other insecticides by selecting a field strain with a commercial spinosad formulation. Bioassays with the field strain, before selection with spinosad, gave resistance ratios (RRs) of 4, 5, 66, 21 and 5 fold for spinosad, indoxacarb, abamectin, imidacloprid and deltamethrin, respectively, in comparison to a laboratory susceptible (Lab-susceptible) strain. After continuous selection of the field strain (Spin-SEL) with spinosad, the RR was increased up to 155 fold; however, the resistance was unstable (RR decreased 1.43 fold) when this strain was not exposed to spinosad for five generations. The Spin-SEL strain did not show cross-resistance to abamectin, indoxacarb or deltamethrin, but showed negative cross-resistance to imidacloprid. Crosses between the Spin-SEL and Lab-susceptible strains revealed an autosomal and incomplete dominant mode of resistance to spinosad. A direct test using a monogenic inheritance model based on Chi-square analysis revealed that the resistance was governed by more than one gene. Moreover, the resistance was neither overcome with the insecticide synergist piperonyl butoxide nor with S,S,S-tributylphosphorotrithioate. Lack of cross-resistance and instability of resistance suggest that rotation with spinosad could be an effective resistance management strategy.

  15. Microhardness and Strain Field Characterization of Self-Reacting Friction Stir and Plug Welds of Dissimilar Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Horton, Karla Renee

    2011-01-01

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA 2014-T6 plate on the advancing side and an AA 2219-T87 plate on the retreating side and a SR-FSW (AA 2014-T6 to AA 2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures.

  16. ICD-10 FIELD TRIALS IN INDIA - A REPORT

    PubMed Central

    Raghuram, R.; Shamasundar, C.

    1992-01-01

    The draft of the tenth revision of the International Classification Of Diseases, Chapter V (ICD-10) was subjected to extensive field trials throughout the world. In India, Nine Field Trial Centres (PTCs) conducted the field trials. The results showed that the ICD-10 was quite adequate in its face-validity, reliability, applicability and ease of use. A brief account of the field trials and the result are reported. PMID:21776123

  17. Large field-induced-strain at high temperature in ternary ferroelectric crystals.

    PubMed

    Wang, Yaojin; Chen, Lijun; Yuan, Guoliang; Luo, Haosu; Li, Jiefang; Viehland, D

    2016-10-13

    The new generation of ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ferroelectric single crystals have potential applications in high power devices due to their surperior operational stability relative to the binary system. In this work, a reversible, large electric field induced strain of over 0.9% at room temperature, and in particular over 0.6% above 380 K was obtained. The polarization rotation path and the phase transition sequence of different compositions in these ternary systems have been determined with increasing electric field applied along [001] direction based on x-ray diffraction data. Thereafter, composition dependence of field-temperature phase diagrams were constructed, which provide compositional and thermal prospectus for the electromechanical properties. It was found the structural origin of the large stain, especially at higher temperature is the lattice parameters modulated by dual independent variables in composition of these ternary solid solution crystals.

  18. Large field-induced-strain at high temperature in ternary ferroelectric crystals

    PubMed Central

    Wang, Yaojin; Chen, Lijun; Yuan, Guoliang; Luo, Haosu; Li, Jiefang; Viehland, D.

    2016-01-01

    The new generation of ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ferroelectric single crystals have potential applications in high power devices due to their surperior operational stability relative to the binary system. In this work, a reversible, large electric field induced strain of over 0.9% at room temperature, and in particular over 0.6% above 380 K was obtained. The polarization rotation path and the phase transition sequence of different compositions in these ternary systems have been determined with increasing electric field applied along [001] direction based on x-ray diffraction data. Thereafter, composition dependence of field-temperature phase diagrams were constructed, which provide compositional and thermal prospectus for the electromechanical properties. It was found the structural origin of the large stain, especially at higher temperature is the lattice parameters modulated by dual independent variables in composition of these ternary solid solution crystals. PMID:27734908

  19. Large field-induced-strain at high temperature in ternary ferroelectric crystals

    NASA Astrophysics Data System (ADS)

    Wang, Yaojin; Chen, Lijun; Yuan, Guoliang; Luo, Haosu; Li, Jiefang; Viehland, D.

    2016-10-01

    The new generation of ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ferroelectric single crystals have potential applications in high power devices due to their surperior operational stability relative to the binary system. In this work, a reversible, large electric field induced strain of over 0.9% at room temperature, and in particular over 0.6% above 380 K was obtained. The polarization rotation path and the phase transition sequence of different compositions in these ternary systems have been determined with increasing electric field applied along [001] direction based on x-ray diffraction data. Thereafter, composition dependence of field-temperature phase diagrams were constructed, which provide compositional and thermal prospectus for the electromechanical properties. It was found the structural origin of the large stain, especially at higher temperature is the lattice parameters modulated by dual independent variables in composition of these ternary solid solution crystals.

  20. Strain fields around high-energy ion tracks in {alpha}-quartz

    SciTech Connect

    Follstaedt, D. M.; Norman, A. K.; Doyle, B. L.; McDaniel, F. D.

    2006-09-15

    Transmission electron microscopy has been used to image the tracks of high-energy {sup 197}Au{sup +26} (374 MeV) and {sup 127}I{sup +18} (241 MeV) ions incident in a nonchanneling direction through a prethinned specimen of hexagonal {alpha}-quartz (SiO{sub 2}). These ions have high electronic stopping powers in quartz, 24 and 19 keV/nm, respectively, which are sufficient to produce a disordered latent track. When the tracks are imaged with diffraction contrast using several different reciprocal lattice vectors, they exhibit a radial strain extending outward from their disordered centerline approximately 16 nm into the crystalline surroundings. The images are consistent with a radial strain field with cylindrical symmetry around the amorphous track, like that found in models developed to account for the lateral expansion of amorphous SiO{sub 2} films produced by irradiation with high-energy ions. These findings provide an experimental basis for increased confidence in such modeling.

  1. Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions

    PubMed Central

    Brearley, Matt B.; Norton, Ian; Rush, Daryl; Hutton, Michael; Smith, Steve; Ward, Linda; Fuentes, Hector

    2016-01-01

    Objective: To examine whether non-heat acclimatized (NHA) emergency responders endure greater physiological and perceptual strain than heat acclimatized (HA) counterparts in tropical field settings. Methods: Eight HA and eight NHA men urban search and rescue personnel had physiological and perceptual responses compared during the initial 4 hours shift of a simulated disaster in tropical conditions (ambient temperature 34.0 °C, 48% relative humidity, wet bulb globe temperature [WBGT] 31.4 °C). Results: From the 90th minute through to end of shift, HA (38.5 °C) sustained a significantly higher gastrointestinal temperature than NHA (38.1 °C) (mean difference 0.4 ± 0.2 °C, 95% confidence interval [CI] 0.2 to 0.7 °C, P = 0.005) despite comparable heart rate (P = 0.30), respiratory rate (P = 0.88), and axilla skin temperature (P = 0.47). Overall, perception of body temperature was similar between cohorts (P = 0.87). Conclusions: The apparent tolerance of greater physiological strain by HA responders occurred in the absence of perceptual differences. PMID:27930487

  2. Performance optimization of a diagnostic system based upon a simulated strain field for fatigue damage characterization

    NASA Astrophysics Data System (ADS)

    Sbarufatti, C.; Manes, A.; Giglio, M.

    2013-11-01

    The work presented hereafter is about the development of a diagnostic system for crack damage detection, localization and quantification on a typical metallic aeronautical structure (skin stiffened through riveted stringers). Crack detection and characterization are based upon strain field sensitivity to damage. The structural diagnosis is carried out by a dedicated smart algorithm (Artificial Neural Network) which is trained on a database of Finite Element simulations relative to damaged and undamaged conditions, providing the system with an accurate predictor at low overall cost. The algorithm, trained on numerical damage experience, is used in a simulated environment to provide reliable preliminary information concerning the algorithm performances for damage diagnosis, thus further reducing the experimental costs and efforts associated with the development and optimization of such systems. The same algorithm has been tested on real experimental strain patterns acquired during real fatigue crack propagation, thus verifying the capability of the numerically trained algorithm for anomaly detection, damage assessment and localization on a real complex structure. The load variability, the discrepancy between the Finite Element Model and the real structure, and the uncertainty in the algorithm training process have been addressed in order to enhance the robustness of the system inference process. Some further algorithm training strategies are discussed, aimed at minimizing the risk for false alarms while maintaining a high probability of damage detection.

  3. Monitoring dyke injection and strain field evolution using shear-wave splitting.

    NASA Astrophysics Data System (ADS)

    Kendall, J.-M.; Verdon, J. P.; Keir, D.; Baird, A.

    2012-04-01

    Magma storage and dyke injection in the shallow crust is a fundamental process in rifting and volcanic environments. The dyking will tend to align with directions of maximum compressive stress, and the associated aligned fracturing and melt migration provides a very effective means of generating seismic anisotropy. Observations of shear-wave splitting provide one of the most unambiguous indicators of such anisotropy. As such, shear-wave splitting can be used to monitor the evolving strain field in volcanic and rifting environments. Here we apply lessons learned from monitoring fracture propagation during the hydraulic stimulation of tight-gas reservoirs. In a number of experiments we observe spatial and temporal variations in shear-wave splitting magnitude and orientation. We invert shear-wave observations for fracture properties, including the tangential and normal compliance, the ratio of which is a good indicator of fluid flow and permeability. Frequency dependent affects can be also used to indicate the length scales of the causative cracks or fractures. We apply these insights to microseismic data recently acquired across the volcanically active Afar triple junction in Ethiopia. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The results help in our understanding of the role of melt in strain accommodation in rifting and volcanic environments.

  4. Field study of age-differentiated strain for assembly line workers in the automotive industry.

    PubMed

    Börner, Kerstin; Scherf, Christian; Leitner-Mai, Bianca; Spanner-Ulmer, Birgit

    2012-01-01

    A field study in an automotive supply industry company was conducted to explore age-differentiated strain of assembly line workers. Subjective and objective data from 23 female workers aged between 27 and 57 years were collected at the workplace belt buckle assembly during morning shifts. Subjects with medication or chronic diseases affecting heart rate and breath rate were excluded. For subjective data generation different questionnaires were used. Before the Work Ability Index and the Munich Chronotype Questionnaire were completed by the subjects. Short questionnaires (strain-ratings, NASA-TLX) directly at begin and end of the work were used for obtaining shift-related data. During the whole shift (6 a.m. - 2.45 p.m.) bodily functions were logged with a wireless chest strap. In addition, the motion of the hand-arm-system was recorded for 30 times, 3 minutes each after a fixed time-schedule. First results show that younger subjects need significant less time for assembly (mean = 14.940 s) compared to older subjects (mean = 17.040 s; t(472.026) = -9.278 , p < 0.01).

  5. Genotyping of Yersinia enterocolitica biotype 1A strains from clinical and nonclinical origins by pulsed-field gel electrophoresis.

    PubMed

    Campioni, Fábio; Falcão, Juliana P

    2014-06-01

    Yersinia enterocolitica biotype 1A (B1A) strains are considered mainly nonpathogenic. However, some studies considered strains of this biotype to be the causal agents of infections in humans and animals. In South America, there are no studies that have compared clinical and nonclinical strains of B1A typed by pulsed-field gel electrophoresis (PFGE) and none that have compared the capability of different enzymes on typing these strains. This study typed 51 Y. enterocolitica B1A strains isolated in Brazil and Chile by PFGE, testing the enzymes XbaI, NotI, and XhoI. The resulting dendrograms discriminated the strains in 47, 40, and 49 pulsotypes generated by the cleavage with the enzymes XbaI, NotI, and XhoI, respectively. The majority of the strains were grouped independently of their clinical or nonclinical origins. The high discriminatory power of PFGE confirmed the heterogeneity of B1A strains but could not divide the strains studied into clusters that differed in the frequency of some virulence genes as observed in studies using other methodologies.

  6. Report on the Summer MONEX Field Phase

    NASA Technical Reports Server (NTRS)

    Fein, J. S.; Kuettner, J. P.

    1980-01-01

    The Summer Monsoon Experiment (MONEX) which was conducted over the Indian Ocean and adjacent land areas from May to August 1979, and overlapped with the second Special Observing Period of the Global Weather Experiment (FGGE). Attention is given to the scientific goals of Summer MONEX which cover (1) planetary scale aspects, (2) synoptic scale aspects, (3) interactions with atmospheric circulation in the Pacific, Southern Hemisphere, Northern midlatitudes, and stratosphere, and (4) numerical simulation and prediction. The observing system and field operations designed to attain these goals are discussed in detail. In conclusion, it is noted that the combined MONEX and FGGE observations should provide an unprecedented data set for a basic study of the monsoon phenomena.

  7. Field-Induced Strain of Shape Memory Alloy Fe-31.2%Pd Using a Capacitance Method in a Pulsed Magnetic Field

    NASA Astrophysics Data System (ADS)

    Sakon, Takuo; Takaha, Atsuo; Matsuoka, Yoshitaka; Obara, Kenji; Saito, Taku; Motokawa, Mitsuhiro; Fukuda, Takashi; Kakeshita, Tomoyuki

    2004-11-01

    A system for the simultaneous measurement of magnetization and magnetic strain, which is designed to be used in a pulsed magnetic field, has been developed. In this system, a capacitor on a sample is used and its capacitance changes with the displacement of a sample due to the strain on the sample in a magnetic field. The most significant feature of this system is that magnetization and strain can be measured simultaneously. It is useful to compare the magnetization and magnetic strain (magnetostriction) with each other. Using this system, we have studied the precise magnetization and magnetic field-induced strain (MFIS) of the martensite metallic compound Fe-31.2%Pd (at.%) at temperatures down to 80 K in martensite phase, which is much lower than the martensitic transformation temperature TM=230 K. Large MFIS has been measured under a pulsed magnetic field with the time constant 6 ms, which corresponds to 80 Hz in frequency. It means that the MFIS occurs even in short-pulse magnetic fields.

  8. Thermal conductivity of bulk GaN—Effects of oxygen, magnesium doping, and strain field compensation

    SciTech Connect

    Simon, Roland B.; Anaya, Julian; Kuball, Martin

    2014-11-17

    The effect of oxygen doping (n-type) and oxygen (O)-magnesium (Mg) co-doping (semi-insulating) on the thermal conductivity of ammonothermal bulk GaN was studied via 3-omega measurements and a modified Callaway model. Oxygen doping was shown to significantly reduce thermal conductivity, whereas O-Mg co-doped GaN exhibited a thermal conductivity close to that of undoped GaN. The latter was attributed to a decreased phonon scattering rate due the compensation of impurity-generated strain fields as a result of dopant-complex formation. The results have great implications for GaN electronic and optoelectronic device applications on bulk GaN substrates.

  9. A stabilized finite element method for finite-strain three-field poroelasticity

    NASA Astrophysics Data System (ADS)

    Berger, Lorenz; Bordas, Rafel; Kay, David; Tavener, Simon

    2017-07-01

    We construct a stabilized finite-element method to compute flow and finite-strain deformations in an incompressible poroelastic medium. We employ a three-field mixed formulation to calculate displacement, fluid flux and pressure directly and introduce a Lagrange multiplier to enforce flux boundary conditions. We use a low order approximation, namely, continuous piecewise-linear approximation for the displacements and fluid flux, and piecewise-constant approximation for the pressure. This results in a simple matrix structure with low bandwidth. The method is stable in both the limiting cases of small and large permeability. Moreover, the discontinuous pressure space enables efficient approximation of steep gradients such as those occurring due to rapidly changing material coefficients or boundary conditions, both of which are commonly seen in physical and biological applications.

  10. Phase field modelling of strain induced crystal growth in an elastic matrix.

    PubMed

    Laghmach, Rabia; Candau, Nicolas; Chazeau, Laurent; Munch, Etienne; Biben, Thierry

    2015-06-28

    When a crystal phase grows in an amorphous matrix, such as a crystallisable elastomer, containing cross-links and/or entanglements, these "topological constraints" need to be pushed away from the crystal phase to allow further crystallization. The accumulation of these topological constraints in the vicinity of the crystal interface may store elastic energy and affect the phase transition. To evaluate the consequences of such mechanism, we introduce a phase field model based on the Flory theory of entropic elasticity. We show that the growth process is indeed sensibly affected, in particular, an exponential increase of the surface energy with the displacement of the interface is induced. This explains the formation of stable nano-crystallites as it is observed in the Strain Induced Crystallization (SIC) of natural rubber. Although simple, the model developed here is able to account for many interesting features of SIC, for instance, the crystallite shapes and their sizes which depend on the applied deformation.

  11. Emergence of antigenic variants of Foot-and-Mouth Disease Virus serotype O in Ecuador and preliminary evaluation of a field strain as a vaccine candidate.

    PubMed

    Maradei, Eduardo; Malirat, Viviana; Beascoechea, Claudia Perez; Espinoza, Ana María; Novo, Sabrina Galdo; Smitsaart, Eliana; Salgado, Gustavo; Mattion, Nora; Toledo, Jorge Rodriguez; Bergmann, Ingrid E

    2014-05-01

    Foot-and-Mouth Disease Virus serotype O has been circulating regularly throughout most provinces of Ecuador, one of the two South American countries that still remain endemic, although satisfactory vaccination coverage was reported. This study concentrates in the characterization of isolates collected during 2008-2011, focusing particularly on the antigenic and immunogenic relationships of the field viruses with the O1/Campos vaccine strain in use in the region and with an experimental vaccine formulated with a representative strain of the 2010 epidemic. The results established that antigenically divergent variants poorly protected by the vaccine in use emerged and co-circulated in a limited period of time. A monovalent vaccine formulated with the representative 2010 strain elicited high antibody titers and protected against challenge with homologous virus. In addition, cross-reactive antibodies to predominant viruses in the region were established. In overall this study indicates the ability of the virus to diversify under field conditions in which a vaccine strain with poor match is applied, and the potential of the selected 2010 field virus as a vaccine candidate for incorporation into strategic antigen banks and/or for addition to current formulations for systematic vaccination, in order to prevent the emergence of even more divergent isolates in the future. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Substrate-mediated strain effect on the role of thermal heating and electric field on metal-insulator transition in vanadium dioxide nanobeams

    PubMed Central

    Kim, Min-Woo; Jung, Wan-Gil; Hyun-Cho; Bae, Tae-Sung; Chang, Sung-Jin; Jang, Ja-Soon; Hong, Woong-Ki; Kim, Bong-Joong

    2015-01-01

    Single-crystalline vanadium dioxide (VO2) nanostructures have recently attracted great attention because of their single domain metal-insulator transition (MIT) nature that differs from a bulk sample. The VO2 nanostructures can also provide new opportunities to explore, understand, and ultimately engineer MIT properties for applications of novel functional devices. Importantly, the MIT properties of the VO2 nanostructures are significantly affected by stoichiometry, doping, size effect, defects, and in particular, strain. Here, we report the effect of substrate-mediated strain on the correlative role of thermal heating and electric field on the MIT in the VO2 nanobeams by altering the strength of the substrate attachment. Our study may provide helpful information on controlling the properties of VO2 nanobeam for the device applications by changing temperature and voltage with a properly engineered strain. PMID:26040637

  13. Balancing ballistic protection against physiological strain: evidence from laboratory and field trials.

    PubMed

    Taylor, Nigel A S; Burdon, Catriona A; van den Heuvel, Anne M J; Fogarty, Alison L; Notley, Sean R; Hunt, Andrew P; Billing, Daniel C; Drain, Jace R; Silk, Aaron J; Patterson, Mark J; Peoples, Gregory E

    2016-02-01

    This project was based on the premise that decisions concerning the ballistic protection provided to defence personnel should derive from an evaluation of the balance between protection level and its impact on physiological function, mobility, and operational capability. Civilians and soldiers participated in laboratory- and field-based studies in which ensembles providing five levels of ballistic protection were evaluated, each with progressive increases in protection, mass (3.4-11.0 kg), and surface-area coverage (0.25-0.52 m(2)). Physiological trials were conducted on volunteers (N = 8) in a laboratory, under hot-dry conditions simulating an urban patrol: walking at 4 km·h(-1) (90 min) and 6 km·h(-1) (30 min or to fatigue). Field-based trials were used to evaluate tactical battlefield movements (mobility) of soldiers (N = 31) under tropical conditions, and across functional tests of power, speed, agility, endurance, and balance. Finally, trials were conducted at a jungle training centre, with soldiers (N = 32) patrolling under tropical conditions (averaging 5 h). In the laboratory, work tolerance was reduced as protection increased, with deep-body temperature climbing relentlessly. However, the protective ensembles could be grouped into two equally stressful categories, each providing a different level of ballistic protection. This outcome was supported during the mobility trials, with the greatest performance decrement evident during fire and movement simulations, as the ensemble mass was increased (-2.12%·kg(-1)). The jungle patrol trials similarly supported this outcome. Therefore, although ballistic protection does increase physiological strain, this research has provided a basis on which to determine how that strain can be balanced against the mission-specific level of required personal protection.

  14. Risk assessment, cross-resistance potential, and biochemical mechanism of resistance to emamectin benzoate in a field strain of house fly (Musca domestica Linnaeus).

    PubMed

    Khan, Hafiz Azhar Ali; Akram, Waseem; Khan, Tiyyabah; Haider, Muhammad Saleem; Iqbal, Naeem; Zubair, Muhammad

    2016-05-01

    Reduced sensitivity to insecticides in insect pests often results in control failures and increases in the dose and frequency of applications, ultimately polluting the environment. Reduced sensitivity to emamectin benzoate, a broad-spectrum agrochemical belonging to the avermectin group of pesticides, was reported in house flies (Musca domestica L.) collected from Punjab, Pakistan, in 2013. The aim of the present study was to investigate the risk for resistance development, biochemical mechanism, and cross-resistance potential to other insecticides in an emamectin benzoate selected (EB-SEL) strain of house flies. A field-collected strain showing reduced sensitivity to emamectin was re-selected in the laboratory for five consecutive generations and compared with a laboratory susceptible (Lab-Susceptible) reference strain, using bioassays. The field strain showed rapid development of resistance to emamectin (resistance ratio (RR) increased from 35.15 to 149.26-fold) as a result of selection experiments; however, resistance declined when the selection pressure uplifted. The EB-SEL strain showed reduction in resistance to abamectin, indoxacarb, and thiamethoxam. The results of synergism experiments using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) enzyme inhibitors and biochemical analyses revealed that the metabolic resistance mechanism was not responsible in developing emamectin resistance in the EB-SEL strain. In conclusion, the risk for the rapid development of emamectin resistance under continuous selection pressure suggests using a multifaceted integrated pest management approach for house flies. Moreover, the instable nature of emamectin resistance in the EB-SEL strain and lack of cross-resistance to other insecticides provide windows for the rotational use of insecticides with different modes of action. This will ultimately reduce emamectin selection pressure and help improving management programs for house flies without polluting the

  15. Stability of Markers Used for Identification of Two Rhizobium galegae Inoculant Strains after Five Years in the Field

    PubMed Central

    Lindström, K.; Lipsanen, P.; Kaijalainen, S.

    1990-01-01

    The stability of identification markers was examined for two Rhizobium galegae inoculant strains after 5 years in the field. The two strains are genetically closely related, but differ in their lipopolysaccharides. Strain HAMBI 540 has lipopolysaccharide of the rough type, whereas that of strain HAMBI 1461 is of the smooth type. The properties that were examined for 10 field isolates of each inoculant type were symbiotic phenotype, phage type, intrinsic antibiotic resistance, maximum growth temperature, lipopolysaccharide and total soluble protein patterns, immunological properties, DNA restriction profiles, and DNA hybridization patterns, which were determined by using nifHDK and recA sequences as probes. Of these properties, all remained stable in soil, with the exception of some variation in intrinsic antibiotic resistance and the acquisition of an extra EcoRI restriction fragment by one of the isolates. Thus, both the rough and the smooth lipopolysaccharide phenotypes persisted equally well in soil. Images PMID:16348119

  16. Band Gap Modulation of Bilayer MoS2 Under Strain Engineering and Electric Field: A Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Nguyen, Chuong V.; Hieu, Nguyen N.; Ilyasov, Victor V.

    2016-08-01

    In this work, we investigate band-gap tuning in bilayer MoS2 by an external electric field and by applied biaxial strain. Our calculations show that the band gaps of bilayer MoS2 can be tuned by the perpendicular electric field or biaxial strain. The band gaps of bilayer MoS2 decrease with increasing applied electric field or biaxial strain. When the electric field was introduced, electronic levels are split due to the separation of the valence sub-band and the conduction sub-band states. Our calculations also show that the change in the band gap of bilayer MoS2 is due to the separation of electronic levels by electric field via the Stark effect. At the electric field E_{Field} = 5.5 V/nm or biaxial strain ɛ = 15%, bilayer MoS2 becomes metallic. The semiconductor-metal phase transition in bilayer MoS2 plays an important role in its application for nanodevices.

  17. TRMM Field Campaigns: Objectives and Status Report

    NASA Technical Reports Server (NTRS)

    Zipser, Edward I.; Heymsfield, Gerald; Kummerow, Christian; Simpson, Joanne; Thiele, Otto; Rutledge, Steven; Dias, Maria Assuncio Silva; Houze, Robert A., Jr.; Yuter, Sandra; Kakar, Ramesh

    1999-01-01

    The Tropical Rainfall Measuring Mission (TRMM) satellite has been sending valuable data since launch in November 1997. Some of the key goals of the joint NASA (US) and NASDA (Japan) mission are: (1) to estimate the four-dimensional diabatic heating in the tropical and subtropical atmosphere, (2) understand the role of latent heating in driving tropical and extratropical circulations, (3) obtain monthly area-averaged estimates of rainfall over the data-sparse oceans, and (4) estimate the relative contribution of convective and stratiform precipitation over different regions during different seasons. The overarching scientific objective is to understand and improve estimates of rainfall and latent heating profiles throughout the global tropics. This requires observations for fundamental understanding of cloud dynamics and microphysics, as well as for validation, testing assumptions and error estimates of cloud-resolving models, forward radiative transfer models, algorithms used to estimate rainfall statistics and vertical structure of precipitation from surface-based radar, and from satellites. Field experiments designed to contribute to this understanding have been conducted in Texas and the South China Sea in spring of 1998, Florida in summer of 1998, and interior Brazil in (boreal) winter 1999. In summer 1999, a major oceanic campaign will be based at Kwajalein Atoll. Some early results will be highlighted, noting some significant contrasts between oceanic and continental convective systems.

  18. Afar-wide Crustal Strain Field from Multiple InSAR Tracks

    NASA Astrophysics Data System (ADS)

    Pagli, C.; Wright, T. J.; Wang, H.; Calais, E.; Bennati Rassion, L. S.; Ebinger, C. J.; Lewi, E.

    2010-12-01

    Onset of a rifting episode in the Dabbahu volcanic segment, Afar (Ethiopia), in 2005 renewed interest in crustal deformation studies in the area. As a consequence, an extensive geodetic data set, including InSAR and GPS measurements have been acquired over Afar and hold great potential towards improving our understanding of the extensional processes that operate during the final stages of continental rupture. The current geodetic observational and modelling strategy has focused on detailed, localised studies of dyke intrusions and eruptions mainly in the Dabbahu segment. However, an eruption in the Erta ‘Ale volcanic segment in 2008, and cluster of earthquakes observed in the Tat Ale segment, are testament to activity elsewhere in Afar. Here we make use of the vast geodetic dataset available to obtain strain information over the whole Afar depression. A systematic analysis of all the volcanic segments, including Dabbahu, Manda-Hararo, Alayta, Tat ‘Ale Erta Ale and the Djibouti deformation zone, is undertaken. We use InSAR data from multiple tracks together with available GPS measurements to obtain a velocity field model for Afar. We use over 300 radar images acquired by the Envisat satellite in both descending and ascending orbits, from 12 distinct tracks in image and wide swath modes, spanning the time period from October 2005 to present time. We obtain the line-of-sight deformation rates from each InSAR track using a network approach and then combine the InSAR velocities with the GPS observations, as suggested by Wright and Wang (2010) following the method of England and Molnar (1997). A mesh is constructed over the Afar area and then we solve for the horizontal and vertical velocities on each node. The resultant full 3D Afar-wide velocity field shows where current strains are being accumulated within the various volcanic segments of Afar, the width of the plate boundary deformation zone and possible connections between distinct volcanic segments on a

  19. Phase field simulations of plastic strain-induced phase transformations under high pressure and large shear

    NASA Astrophysics Data System (ADS)

    Javanbakht, Mahdi; Levitas, Valery I.

    2016-12-01

    Pressure and shear strain-induced phase transformations (PTs) in a nanograined bicrystal at the evolving dislocations pile-up have been studied utilizing a phase field approach (PFA). The complete system of PFA equations for coupled martensitic PT, dislocation evolution, and mechanics at large strains is presented and solved using the finite element method (FEM). The nucleation pressure for the high-pressure phase (HPP) under hydrostatic conditions near a single dislocation was determined to be 15.9 GPa. Under shear, a dislocation pile-up that appears in the left grain creates strong stress concentration near its tip and significantly increases the local thermodynamic driving force for PT, which causes nucleation of HPP even at zero pressure. At pressures of 1.59 and 5 GPa and shear, a major part of a grain transforms to HPP. When dislocations are considered in the transforming grain as well, they relax stresses and lead to a slightly smaller stationary HPP region than without dislocations. However, they strongly suppress nucleation of HPP and require larger shear. Unexpectedly, the stationary HPP morphology is governed by the simplest thermodynamic equilibrium conditions, which do not contain contributions from plasticity and surface energy. These equilibrium conditions are fulfilled either for the majority of points of phase interfaces or (approximately) in terms of stresses averaged over the HPP region or for the entire grain, despite the strong heterogeneity of stress fields. The major part of the driving force for PT in the stationary state is due to deviatoric stresses rather than pressure. While the least number of dislocations in a pile-up to nucleate HPP linearly decreases with increasing applied pressure, the least corresponding shear strain depends on pressure nonmonotonously. Surprisingly, the ratio of kinetic coefficients for PT and dislocations affect the stationary solution and the nanostructure. Consequently, there are multiple stationary solutions

  20. Draft Genome Sequence of Strain ATCC 33958, Reported To Be Elizabethkingia miricola

    PubMed Central

    Matyi, Stephanie A.; Hoyt, Peter R.; Ayoubi-Canaan, Patricia; Hasan, Nabeeh A.

    2015-01-01

    We report the draft genome of Elizabethkingia strain ATCC 33958, which has been classified as Elizabethkingia miricola. Similar to other Elizabethkingia species, the ATCC 33958 draft genome contains numerous β-lactamase genes. ATCC 33958 also harbors a urease gene cluster which supports classification as E. miricola. PMID:26205869

  1. Strain characterization of fin-shaped field effect transistors with SiGe stressors using nanobeam electron diffraction

    SciTech Connect

    Kim, Sun-Wook; Byeon, Dae-Seop; Jang, Hyunchul; Koo, Sang-Mo; Ko, Dae-Hong; Lee, Hoo-Jeong

    2014-08-25

    This study undertook strain analysis on fin-shaped field effect transistor structures with epitaxial Si{sub 1−x}Ge{sub x} stressors, using nano-beam electron diffraction and finite elements method. Combining the two methods disclosed dynamic strain distribution in the source/drain and channel region of the fin structure, and the effects of dimensional factors such as the stressor thickness and fin width, offering valuable information for device design.

  2. A Guide to Writing Student Laboratory and Field Research Reports.

    ERIC Educational Resources Information Center

    Schlenker, Richard M.

    This document outlines the procedures to be followed in writing a field or research report. It describes the rationale behind a good report and explains the proper format and use of title, introduction, methods, data, discussion, conclusion, references, and abstract or summary elements. This guide gives aids to writing a good report. Finally, it…

  3. A Guide to Writing Student Laboratory and Field Research Reports.

    ERIC Educational Resources Information Center

    Schlenker, Richard M.

    This document outlines the procedures to be followed in writing a field or research report. It describes the rationale behind a good report and explains the proper format and use of title, introduction, methods, data, discussion, conclusion, references, and abstract or summary elements. This guide gives aids to writing a good report. Finally, it…

  4. Manus Water Isotope Investigation Field Campaign Report

    SciTech Connect

    Conroy, Jessica L; Cobb, Kim M; Noone, David

    2016-03-01

    The objective of this field campaign was to investigate climatic controls on the stable isotopic composition of water vapor, precipitation, and seawater in the western tropical Pacific. Simultaneous measurements of the stable isotopic composition of vapor and precipitation from April 28 to May 8, 2013, at the Manus Tropical Western Pacific Atmospheric Radiation Measurement site, provided several key insights into the nature of the climate signal archived in precipitation and vapor isotope ratios. We observed a large shift from lower to higher isotopic values in vapor and precipitation because of the passage of a mesoscale convective system west of the site and a transition from a regional stormy period into a more quiescent period. During the quiescent period, the stable isotopic composition of vapor and precipitation indicated the predominance of oceanic evaporation in determining the isotopic composition of boundary-layer vapor and local precipitation. There was not a consistent relationship between intra-event precipitation amount at the site and the stable isotopic composition of precipitation, thus challenging simplified assumptions about the isotopic “amount effect” in the tropics on the time scale of individual storms. However, some storms did show an amount effect, and deuterium excess values in precipitation had a significant relationship with several meteorological variables, including precipitation, temperature, relative humidity, and cloud base height across all measured storms. The direction of these relationships points to condensation controls on precipitation deuterium excess values on intra-event time scales. The relationship between simultaneous measurements of vapor and precipitation isotope ratios during precipitation events indicates the ratio of precipitation-to-vapor isotope ratios can diagnose precipitation originating from a vapor source unique from boundary-layer vapor and rain re-evaporation.

  5. Direct estimation of the lateral strain field using a double oscillating point spread function with a scaling factor estimator

    NASA Astrophysics Data System (ADS)

    Liebgott, Herve; Fromageau, Jeremie; Wilhjelm, Jens E.; Vray, Didier; Delachartre, Philippe

    2004-04-01

    This work presents a new approach to lateral strain estimation in the field of tissue elasticity imaging with ultrasound. A particular beamforming is used to produce a point spread function (PSF) with lateral oscillations. Lateral RF signals can then be considered as the juxtaposition of RF samples coming from the same depth. This enables to estimate the lateral strain with a scaling factor estimator applied to the lateral signals. The approach is validated in simulation on a medium stretched only in the lateral direction. The estimation is unbiased for lateral strain values from 0.5 to 7 % with standard deviation less than 0.5 %.

  6. Identification of a novel equine infectious anemia virus field strain isolated from feral horses in southern Japan.

    PubMed

    Dong, Jian-Bao; Zhu, Wei; Cook, Frank R; Goto, Yoshitaka; Horii, Yoichiro; Haga, Takeshi

    2013-02-01

    Although equine infectious anemia (EIA) was described more than 150 years ago, complete genomic sequences have only been obtained from two field strains of EIA virus (EIAV), EIAV(Wyoming) and EIAV(Liaoning). In 2011, EIA was detected within the distinctive feral Misaki horse population that inhabits the Toi-Cape area of southern Japan. Complete proviral sequences comprising a novel field strain were amplified directly from peripheral blood of one of these EIAV-infected horses and characterized by nucleotide sequencing. The complete provirus of Miyazaki2011-A strain is 8208 bp in length with an overall genomic organization typical of EIAV. However, this field isolate possesses just 77.2 and 78.7 % nucleotide sequence identity with the EIAV(Wyoming) and EIAV(Liaoning) strains, respectively, while similarity plot analysis suggested all three strains arose independently. Furthermore, phylogenetic studies using sequences obtained from all EIAV-infected Misaki horses against known viral strains strongly suggests these Japanese isolates comprise a separate monophyletic group.

  7. Arctic Clouds Infrared Imaging Field Campaign Report

    SciTech Connect

    Shaw, J. A.

    2016-03-01

    The Infrared Cloud Imager (ICI), a passive thermal imaging system, was deployed at the North Slope of Alaska site in Barrow, Alaska, from July 2012 to July 2014 for measuring spatial-temporal cloud statistics. Thermal imaging of the sky from the ground provides high radiometric contrast during night and polar winter when visible sensors and downward-viewing thermal sensors experience low contrast. In addition to demonstrating successful operation in the Arctic for an extended period and providing data for Arctic cloud studies, a primary objective of this deployment was to validate novel instrument calibration algorithms that will allow more compact ICI instruments to be deployed without the added expense, weight, size, and operational difficulty of a large-aperture onboard blackbody calibration source. This objective was successfully completed with a comparison of the two-year data set calibrated with and without the onboard blackbody. The two different calibration methods produced daily-average cloud amount data sets with correlation coefficient = 0.99, mean difference = 0.0029 (i.e., 0.29% cloudiness), and a difference standard deviation = 0.054. Finally, the ICI instrument generally detected more thin clouds than reported by other ARM cloud products available as of late 2015.

  8. Molecular typing of Japanese field isolates and live commercial vaccine strain of Mycoplasma synoviae using improved pulsed-field gel electrophoresis and vlhA gene sequencing.

    PubMed

    Harada, Kazuki; Kijima-Tanaka, Mayumi; Uchiyama, Mariko; Yamamoto, Tomoko; Oishi, Koji; Arao, Megumi; Takahashi, Toshio

    2009-12-01

    In the present study, pulsed-field gel electrophoresis (PFGE) and vlhA gene sequence analysis were applied and verified for typing the Mycoplasma synoviae live vaccine MS-H strain and field isolates from diseased chickens in Japan. The previously published PFGE protocol using SmaI digestion could not allow the discrimination of two of the 11 M. synoviae field isolates from the vaccine strain and had relatively low discrimination power (D = 0.885). On the other hand, our new PFGE protocols using BlnI and BamHI digestions as well as the vlhA sequence analysis allowed the discrimination of all 11 M. synoviae field isolates from the vaccine strain. In addition, these PFGE protocols using BlnI and BamHI digestions generated unique fragment patterns in epidemiologically unrelated isolates, including those with identical SmaI-digested patterns or vlhA gene sequences (D = 0.987 and 1.000, respectively), and generated indistinguishable or closely related patterns in epidemiologically related isolates. Therefore, we believe that they would be useful tools to determine whether M. synoviae clinical isolates from diseased chickens are derived from the vaccine strain or wild-type strain and to further elucidate the epidemiology of M. synoviae infection.

  9. Phase field approach to martensitic phase transformations with large strains and interface stresses

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.

    2014-10-01

    Thermodynamically consistent phase field theory for multivariant martensitic transformations, which includes large strains and interface stresses, is developed. Theory is formulated in a way that some geometrically nonlinear terms do not disappear in the geometrically linear limit, which in particular allowed us to introduce the expression for the interface stresses consistent with the sharp interface approach. Namely, for the propagating nonequilibrium interface, a structural part of the interface Cauchy stresses reduces to a biaxial tension with the magnitude equal to the temperature-dependent interface energy. Additional elastic and viscous contributions to the interface stresses do not require separate constitutive equations and are determined by solution of the coupled system of phase field and mechanics equations. Ginzburg-Landau equations are derived for the evolution of the order parameters and temperature evolution equation. Boundary conditions for the order parameters include variation of the surface energy during phase transformation. Because elastic energy is defined per unit volume of unloaded (intermediate) configuration, additional contributions to the Ginzburg-Landau equations and the expression for entropy appear, which are important even for small strains. A complete system of equations for fifth- and sixth-degree polynomials in terms of the order parameters is presented in the reference and actual configurations. An analytical solution for the propagating interface and critical martensitic nucleus which includes distribution of components of interface stresses has been found for the sixth-degree polynomial. This required resolving a fundamental problem in the interface and surface science: how to define the Gibbsian dividing surface, i.e., the sharp interface equivalent to the finite-width interface. An unexpected, simple solution was found utilizing the principle of static equivalence. In fact, even two equations for determination of the

  10. Observation of Rashba zero-field spin splitting in a strained germanium 2D hole gas

    SciTech Connect

    Morrison, C. Rhead, S. D.; Foronda, J.; Leadley, D. R.; Myronov, M.; Wiśniewski, P.

    2014-11-03

    We report the observation, through Shubnikov-de Haas oscillations in the magnetoresistance, of spin splitting caused by the Rashba spin-orbit interaction in a strained Ge quantum well epitaxially grown on a standard Si(001) substrate. The Shubnikov-de Haas oscillations display a beating pattern due to the spin split Landau levels. The spin-orbit parameter and Rashba spin-splitting energy are found to be 1.0 × 10{sup −28 } eVm{sup 3} and 1.4 meV, respectively. This energy is comparable to 2D electron gases in III-V semiconductors, but substantially larger than in Si, and illustrates the suitability of Ge for modulated hole spin transport devices.

  11. Manipulation of magnetic phase separation and orbital occupancy in manganites by strain engineering and electric field

    NASA Astrophysics Data System (ADS)

    Cui, Bin; Song, Cheng; Pan, Feng; Key Laboratory of Advanced Materials (MOE) Team

    2015-03-01

    The modification of electronic phases in correlated oxides is one of the core issues of condensed matter. We report the reversible control of ferromagnetic phase transition in manganite films by ionic liquid gating, replicating the La1-xSrxMnO3 (LSMO) phase diagram. The formation and annihilation of an insulating and magnetically hard phase in the soft magnetic matrix, which randomly nucleates and grows across the film, is directly observed under different gate voltages (VG) . The realization of reversible metal-insulator transition in colossal magnetoresistance materials can lead to the development of four-state memories. The orbital occupancy and magnetic anisotropy of LSMO films are manipulated by VG in a reversible and quantitative manner. Positive and negative VG increases and reduces the occupancy of the orbital and magnetic anisotropy that were initially favored by strain (irrespective of tensile and compressive), respectively. This finding fills in the blank of electrical manipulation of four degrees of freedom in correlated system.

  12. Report on Non-Contact DC Electric Field Sensors

    SciTech Connect

    Miles, R; Bond, T; Meyer, G

    2009-06-16

    This document reports on methods used to measure DC electrostatic fields in the range of 100 to 4000 V/m using a non-contact method. The project for which this report is written requires this capability. Non-contact measurements of DC fields is complicated by the effect of the accumulation of random space-charges near the sensors which interfere with the measurement of the field-of-interest and consequently, many forms of field measurements are either limited to AC measurements or use oscillating devices to create pseudo-AC fields. The intent of this document is to report on methods discussed in the literature for non-contact measurement of DC fields. Electric field meters report either the electric field expressed in volts per distance or the voltage measured with respect to a ground reference. Common commercial applications for measuring static (DC) electric fields include measurement of surface charge on materials near electronic equipment to prevent arcing which can destroy sensitive electronic components, measurement of the potential for lightning to strike buildings or other exposed assets, measurement of the electric fields under power lines to investigate potential health risks from exposure to EM fields and measurement of fields emanating from the brain for brain diagnostic purposes. Companies that make electric field sensors include Trek (Medina, NY), MKS Instruments, Boltek, Campbell Systems, Mission Instruments, Monroe Electronics, AlphaLab, Inc. and others. In addition to commercial vendors, there are research activities continuing in the MEMS and optical arenas to make compact devices using the principles applied to the larger commercial sensors.

  13. Spin- and valley-dependent electronic band structure and electronic heat capacity of ferromagnetic silicene in the presence of strain, exchange field and Rashba spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Hoi, Bui Dinh; Yarmohammadi, Mohsen; Kazzaz, Houshang Araghi

    2017-10-01

    We studied how the strain, induced exchange field and extrinsic Rashba spin-orbit coupling (RSOC) enhance the electronic band structure (EBS) and electronic heat capacity (EHC) of ferromagnetic silicene in presence of external electric field (EF) by using the Kane-Mele Hamiltonian, Dirac cone approximation and the Green's function approach. Particular attention is paid to investigate the EHC of spin-up and spin-down bands at Dirac K and K‧ points. We have varied the EF, strain, exchange field and RSOC to tune the energy of inter-band transitions and consequently EHC, leading to very promising features for future applications. Evaluation of EF exhibits three phases: Topological insulator (TI), valley-spin polarized metal (VSPM) and band insulator (BI) at given aforementioned parameters. As a new finding, we have found a quantum anomalous Hall phase in BI regime at strong RSOCs. Interestingly, the effective mass of carriers changes with strain, resulting in EHC behaviors. Here, exchange field has the same behavior with EF. Finally, we have confirmed the reported and expected symmetry results for both Dirac points and spins with the study of valley-dependent EHC.

  14. Analysis of Genomic Diversity among Helicobacter pylori Strains Isolated from Iranian Children by Pulsed Field Gel Electrophoresis

    PubMed Central

    Falsafi, Tahereh; Sotoudeh, Nazli; Feizabadi, Mohammad-Mehdi; Mahjoub, Fatemeh

    2014-01-01

    Objective: Presence of genomic diversity among Helicobacter pylori (H. pylori) strains have been suggested by numerous investigators. Little is known about diversity of H. pylori strains isolated from Iranian children and their association with virulence of the strains. Our purpose was to assess the degree of genomic diversity among H. pylori strains isolated from Iranian-children, on the basis of vacA genotype, cagA status of the strains, sex, age as well as the pathological status of the patients. Methods: Genomic DNA from 44 unrelated H. pylori strains isolated during 1997–2009, was examined by pulse-field gel electrophoresis (PFGE). Pathological status of the patients was performed according to the modified Sydney-system and genotype/status of vacA/cagA genes was determined by PCR. PFGE was performed using XbaI restriction-endonuclease and the field inversion-gel electrophoresis system. Findings: No significant relationship was observed between the patterns of PFGE and the cagA/vacA status/genotype. Also no relationship was observed between age, sex, and pathological status of the children and the PFGE patterns of their isolates. Similar conclusion was obtained by Total Lab software. However, more relationship was observed between the strains isolated in the close period (1997–2009, 2001–2003, 2005–2007, and 2007–2009) and more difference was observed among those obtained in the distant periods (1997 and 2009). Conclusion: H. pylori strains isolated from children in Iran are extremely diverse and this diversity is not related to their virulence characteristics. Occurrence of this extreme diversity may be related to adaptation of H. pylori strains to variable living conditions during transmission between various host individuals. PMID:26019775

  15. FIELD ANALYTICAL SCREENING PROGRAM: PCB METHOD - INNOVATIVE TECHNOLOGY REPORT

    EPA Science Inventory

    This innovative technology evaluation report (ITER) presents information on the demonstration of the U.S. Environmental Protection Agency (EPA) Region 7 Superfund Field Analytical Screening Program (FASP) method for determining polychlorinated biphenyl (PCB) contamination in soil...

  16. FIELD ANALYTICAL SCREENING PROGRAM: PCB METHOD - INNOVATIVE TECHNOLOGY REPORT

    EPA Science Inventory

    This innovative technology evaluation report (ITER) presents information on the demonstration of the U.S. Environmental Protection Agency (EPA) Region 7 Superfund Field Analytical Screening Program (FASP) method for determining polychlorinated biphenyl (PCB) contamination in soil...

  17. [Repetitive strain injury (RSI); a report from the Health Council of the Netherlands].

    PubMed

    Willems, J H B M

    2002-10-19

    The Health Council of the Netherlands has published its advisory report on Repetitive Strain Injury (RSI). The report provides clear information on the state of this syndrome, including the definition of the problem, the epidemiology, various hypothetical pathophysiological mechanisms, occupational and personal risk factors, and possible methods of treatment. The council states that with regard to the last aspect, too few data are available to draw any conclusion as to the most promising therapy. Nevertheless, patients should get consistent advice from their GP or company doctor. The council emphasises that encouraging physical exercise and eliminating any possible causative strain should be part of an integrated approach, embracing work-related psychosocial and personal issues. Of particular interest is the council's advice to prevent RSI by improving the physical condition and by selective training of muscle function. The report recommends that more research be carried out in order to provide insight into the effectiveness of the treatment of RSI.

  18. Deep sequencing and variant analysis of an Italian pathogenic field strain of equine infectious anaemia virus.

    PubMed

    Cappelli, K; Cook, R F; Stefanetti, V; Passamonti, F; Autorino, G L; Scicluna, M T; Coletti, M; Verini Supplizi, A; Capomaccio, S

    2017-03-15

    Equine infectious anaemia virus (EIAV) is a lentivirus with an almost worldwide distribution that causes persistent infections in equids. Technical limitations have restricted genetic analysis of EIAV field isolates predominantly to gag sequences resulting in very little published information concerning the extent of inter-strain variation in pol, env and the three ancillary open reading frames (ORFs). Here, we describe the use of long-range PCR in conjunction with next-generation sequencing (NGS) for rapid molecular characterization of all viral ORFs and known transcription factor binding motifs within the long terminal repeat of two EIAV isolates from the 2006 Italian outbreak. These isolates were from foals believed to have been exposed to the same source material but with different clinical histories: one died 53 days post-infection (SA) while the other (DE) survived 5 months despite experiencing multiple febrile episodes. Nucleotide sequence identity between the isolates was 99.358% confirming infection with the same EIAV strain with most differences comprising single nucleotide polymorphisms in env and the second exon of rev. Although the synonymous:non-synonymous nucleotide substitution ratio was approximately 2:1 in gag and pol, the situation is reversed in env and ORF3 suggesting these sequences are subjected to host-mediated selective pressure. EIAV proviral quasispecies complexity in vivo has not been extensively investigated; however, analysis suggests it was relatively low in SA at the time of death. These results highlight advantages of NGS for molecular characterization of EIAV namely it avoids potential artefacts generated by traditional composite sequencing strategies and can provide information about viral quasispecies complexity. © 2017 Blackwell Verlag GmbH.

  19. Study of effectiveness of bioluminescent reporter phage assay on Y. pseudotuberculosis strains.

    PubMed

    Mitiashvili, M R

    2013-05-01

    The method describes the phage-mediated transduction of a bioluminescent phenotype to cultivated Y. pseudotuberculosis cells which are subsequently measured using a microplate luminometer. Reporter phage assay is rapid detection technique and its efficiency is not affected by presence of contaminating bacteria, no sample preparation is needed and it has the ability to test multiple samples simultaneously in a 96-well microtiter plate format. Experiments were performed to develop the rapid detection technique for Y. pseudotuberculosis strains and study the ability of a reporter Yersinia phage to confer a bioluminescent signal to Y. pseudotuberculosis strains under different environmental conditions (media, temperature, bacterial number) for detection. Further, to determine if the Yersinia phage can detect Y. pseudotuberculosis in presence of other bacterial species. The results revealed that the developed reporter phage assay is not effective against wide range of Y. pseudotuberculosis. Y. pseudotuberculosis could be rapidly detected within 30 minutes at 28°C. The reporter phage assay could detect luminescence within 45 minutes when the bacterial cells were at the minimal concentration 105 cells/mL. The optimal detectable concentrations were 106-107 cells/mL at 28 and 37°C. The reporter phage assay could detect Y. pseudotuberculosis within 30 minutes in presence of other enteric bacteria without selective enrichment. It should be noted that the Yersinia reporter phage is specific to Yersinia pestis strains and it can be used to detect Y. pseudotuberculosis when samples exclude the existence of Y. pestis strains. In the presented study this aspect was foreseen.

  20. Electric-field-induced AFE-FE transitions and associated strain/preferred orientation in antiferroelectric PLZST

    PubMed Central

    Lu, Teng; Studer, Andrew J.; Noren, Lasse; Hu, Wanbiao; Yu, Dehong; McBride, Bethany; Feng, Yujun; Withers, Ray L.; Chen, Hua; Xu, Zhuo; Liu, Yun

    2016-01-01

    Electric-field-induced, antiferroelectric-ferroelectric (AFE-FE) phase transitions are common for AFE materials. To date, the strain and preferred orientation evolution as well as the role of the intermediate FE state during the successive AFE-FE-AFE phase transitions has not been clear. To this end, we have herein studied a typical AFE Pb0.97La0.02(Zr0.56Sn0.33Ti0.11)O3 (PLZST) material using in-situ neutron diffraction. It is striking that the AFE-FE phase transition is not fully reversible: in the electric-field-induced FE state, the induced strain exhibits an elliptical distribution, which in turn leads to significant preferred orientation in the final AFE state after withdrawal of the applied electric-field. The ω-dependent neutron diffraction patterns show clear evidence of the induced strain distribution and associated preferred orientation arising from the AFE-FE phase transition. The current work also provides an explanation for several temperature and electric-field dependent dielectric anomalies as well as unrecovered strain change which appear in AFE materials after exposure to sufficiently high electric fields. PMID:27025685

  1. Lactose consuming strains of Xanthomonas citri subsp. citri (Xcc) insight into the emergence of natural field resources for xanthan gum production.

    PubMed

    Ramezani, Aghdas; Jafari, Mahyat; Goodarzi, Tannaz; Alavi, Seyed Mehdi; Salmanian, Ali Hatef; Azin, Mehrdad

    2014-05-01

    Xanthomonas genus possesses a low level of β-galactosidase gene expression and is therefore unable to produce xanthan gum in lactose-based media. In this study, we report the emergence of some natural field strains of Xanthomonas citri subsp. citri (Xcc) capable to use lactose as a sole carbon source to produce xanthan gum. From 210 Xcc strains isolated from key lime (C. aurantifolia), 27 showed the capacity to grow on lactose containing medium. Xcc lactose consuming strains demonstrated a good level of xanthan production. Amongst all, NIGEBK37 produced the greatest (14.62 g/l) amount of xanthan gum in experimental laboratory conditions. By evaluating the viscosity of the biopolymer at 25 °C, it was demonstrated that xanthan synthesized by strain NIGEBK37 has the highest viscosity (44,170.66 cP). Our results were indicative for the weakness of a commercial strain of Xanthomonas campestris pv. Campestris DSM1706 (Xcc/DSM1706) to produce xanthan in lactose containing medium.

  2. Use of pulsed-field gel electrophoresis to monitor a five-strain mixture of Listeria monocytogenes in frankfurter packages.

    PubMed

    Porto, Anna C S; Wonderling, Laura; Call, Jeffrey E; Luchansky, John B

    2003-08-01

    In a previous study, the viability of a five-strain mixture of Listeria monocytogenes (including Scott A [serotype 4b, clinical isolate], 101M [serotype 4b, beef-pork sausage isolate], F6854 [serotype 1/2a, turkey frankfurter isolate], H7776 [serotype 4b, frankfurter isolate], and MFS-2 [serotype 1/2a, pork plant isolate]) was monitored during refrigerated storage of frankfurters prepared with and without 3.0% added potassium lactate. Throughout a 90-day period of storage at 4 degrees C, the initial inoculum level of 20 CFU per package remained relatively constant in packages containing frankfurters prepared with potassium lactate, but pathogen counts increased to 4.6 log10 CFU in packages containing frankfurters prepared without added potassium lactate. To determine which of the five strains persisted under these conditions, randomly selected colonies obtained after 28 and 90 days of refrigerated storage of frankfurters were analyzed by pulsed-field gel electrophoresis (PFGE) with the restriction enzyme SmaI to generate distinct banding patterns for each of the five strains. Then, with the use of PFGE as a tool for identification, the percentages of the strains on days 28 and 90 of the growth study were compared. In the absence of any added potassium lactate in the product, 43% of the 58 isolates recovered on day 28 were identified as strain Scott A, 12% were identified as strain 101M, 22% were identified as strain F6854, 10% were identified as strain H7776, and 12% were identified as strain MFS-2. However, by day 90, an appreciable number (83%) of the 60 isolates analyzed were identified as strain MFS-2. In packages containing frankfurters formulated with 3.0% potassium lactate, all five strains were present at frequencies of 5 to 36% among the 19 isolates tested on day 28; however, by day 90, strain MFS-2 made up the statistical majority (63%) of the 27 isolates tested. The results of this study indicate that strain MFS-2, a serotype 1/2a isolate recovered from

  3. Job strain, sleep and alertness in shift working health care professionals -- a field study.

    PubMed

    Karhula, Kati; Härmä, Mikko; Sallinen, Mikael; Hublin, Christer; Virkkala, Jussi; Kivimäki, Mika; Vahtera, Jussi; Puttonen, Sampsa

    2013-01-01

    We explored the associations of job strain with sleep and alertness of shift working female nurses and nursing assistants. Participants (n=95) were recruited from the Finnish Public Sector Study, from hospital wards that belonged to the top or bottom quartiles on job strain. Participants' own job strain was at least as high in high-strain group or low in low-strain group as the ward's average. The study included three-week measurements with sleep diary and actigraphy. Psychomotor Vigilance Test (PVT) was performed during one pre-selected morning and night shift and a day off. Sleep efficiency before morning shifts was lower in the high-strain than low-strain group (p=0.03). Low-strain group took more often (72 vs. 45%; p<0.01) and longer naps (62 vs. 35 min; p=0.01) before the first night shift than high-strain group. Difficulties initiating sleep were more common in high-strain group, especially after evening shifts (p<0.01). High-strain group had more often at least one lapse in PVT during the night shift (p=0.02). Average sleep duration (06:49 h) and efficiency (89%) did not differ between these groups. In conclusion, high job strain is associated with difficulties initiating sleep and reduced psychomotor vigilance in night shifts. Shift working contributed to impaired sleep in both high and low job strain group. Individual and organization-based actions are needed to promote sufficient sleep in shift working nurses, especially with high job strain.

  4. Isolation and characterization of Klebsiella oxytoca strain degrading crude oil from a Tunisian off-shore oil field.

    PubMed

    Chamkha, Mohamed; Trabelsi, Yosra; Mnif, Sami; Sayadi, Sami

    2011-12-01

    A facultatively anaerobic, Gram-negative, mesophilic, moderately halotolerant, non-motile, and non-sporulated bacterium, designated strain BSC5 was isolated from an off-shore "Sercina" oil field, located near the Kerkennah island, Tunisia. Yeast extract was not required for growth. Phenotypic characteristics and phylogenetic analysis of the 16S rRNA gene sequence of strain BSC5 revealed that it was related to members of the genus Klebsiella, being most closely related to the type strain of K. oxytoca (99% sequence similarity). Strain BSC5 was capable of using aerobically the crude oil as substrate growth. The growth of strain BSC5 on crude oil was followed by measuring the OD(600 nm) and by enumeration of viable cells at different culture's time. GC-MS analysis showed that strain BSC5 was capable of degrading a wide range of aliphatic hydrocarbons from C(13) to C(30) . The biodegradation rate for n -alkanes reached 44% and 75%, after 20 and 45 days of incubation, respectively. Addition of the synthetic surfactant, Tween 80, accelerated the crude oil degradation. The biodegradation rate for n -alkanes reached 61% and 98%, after 20 and 45 days of incubation, respectively. Moreover, three aromatic compounds, p -hydroxybenzoate, protocatechuate and gentisate, were metabolized completely by strain BSC5 after 24 h, under aerobic conditions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Genetic Diversity of Streptococcus suis Strains Isolated from Pigs and Humans as Revealed by Pulsed-Field Gel Electrophoresis

    PubMed Central

    Berthelot-Hérault, Florence; Marois, Corinne; Gottschalk, Marcelo; Kobisch, Marylène

    2002-01-01

    The genetic diversity of 123 Streptococcus suis strains of capsular types 2, 1/2, 3, 7, and 9, isolated from pigs in France and from humans in different countries, was evaluated by pulsed-field gel electrophoresis (PFGE) of DNA restricted with SmaI. The method was highly discriminative (D = 0.98), results were reproducible, and the PFGE analysis was easy to interpret. Among all S. suis strains, 74 PFGE patterns were shown. At 60% homology, three groups (A, B, and C) were identified, and at 69% homology, eight subgroups (a to h) were observed. Strains isolated from diseased pigs or from humans were statistically clustered in group B, especially in subgroup d. By contrast, S. suis strains isolated from clinically healthy pigs were preferentially included in subgroup b of group A. Relationships could be established between capsular types 1/2, 3, and 9 and groups A, e, and B, respectively. S. suis strains isolated from humans were homogeneous, and a very high level of association between these strains and four DNA patterns was observed. The PFGE used in this study is a very useful tool for evaluating the genetic diversity of S. suis strains, and it would be used for epidemiological investigations. PMID:11825980

  6. Genetic diversity of Streptococcus suis strains isolated from pigs and humans as revealed by pulsed-field gel electrophoresis.

    PubMed

    Berthelot-Hérault, Florence; Marois, Corinne; Gottschalk, Marcelo; Kobisch, Marylène

    2002-02-01

    The genetic diversity of 123 Streptococcus suis strains of capsular types 2, 1/2, 3, 7, and 9, isolated from pigs in France and from humans in different countries, was evaluated by pulsed-field gel electrophoresis (PFGE) of DNA restricted with SmaI. The method was highly discriminative (D = 0.98), results were reproducible, and the PFGE analysis was easy to interpret. Among all S. suis strains, 74 PFGE patterns were shown. At 60% homology, three groups (A, B, and C) were identified, and at 69% homology, eight subgroups (a to h) were observed. Strains isolated from diseased pigs or from humans were statistically clustered in group B, especially in subgroup d. By contrast, S. suis strains isolated from clinically healthy pigs were preferentially included in subgroup b of group A. Relationships could be established between capsular types 1/2, 3, and 9 and groups A, e, and B, respectively. S. suis strains isolated from humans were homogeneous, and a very high level of association between these strains and four DNA patterns was observed. The PFGE used in this study is a very useful tool for evaluating the genetic diversity of S. suis strains, and it would be used for epidemiological investigations.

  7. a Computational Study of Strain Effects in the Band-To Carbon Nanotube Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Yousefi, Reza; Ghoreishi, Seyyed Saleh

    2012-11-01

    In this paper, the transport properties of the band-to-band-tunneling carbon nanotube field-effect transistors (BTBT-CNTFETs) under uniaxial strain are studied, with the nonequilibrium Green's function (NEGF) formalism. The effects of the uniaxial strain on the electrical properties, such as the ON current (ION), OFF current (IOFF), ION/IOFF ratio, subthreshold swing and intrinsic delay are evaluated. It was observed that the uniaxial strain has strong effects on the transport properties of these transistors. The results show that appropriate uniaxial strain, although degrades the ON current and the intrinsic delay, it also decreases the power consumption of the BTBT-CNTFETs and as a result can be used for low-power applications.

  8. A comparison of susceptibility to Myxobolus cerebralis among strains of rainbow trout and steelhead in field and laboratory trials

    USGS Publications Warehouse

    Densmore, Christine L.; Blazer, V.S.; Cartwright, Deborah D.; Schill, W.B.; Schachte, J.H.; Petrie, C.J.; Batur, M.V.; Waldrop, T.B.; Mack, A.; Pooler, P.S.

    2001-01-01

    Three strains of rainbow trout and steelhead Oncorhynchus mykiss were evaluated for the presence of whirling disease in field and laboratory trials. In the field exposures, fingerling Salmon River steelhead and Cayuga Lake and Randolph strains of rainbow trout were placed in wire cages in an earthen, stream-fed pond in New York State that was known to harbor Myxobolus cerebralis. Control fish were held at another hatchery that was free of whirling disease. In the controlled trials at the National Fish Health Research Laboratory, fingerling steelhead and Cayuga Lake and Mount Lassen rainbow trout were exposed to triactinomyxons at low (200 triactinomyxons/fish) or high (2,000 triactinomyxons/fish) levels for 2 h. Controls of each group were sham-exposed. Following an incubation period of 154 d for laboratory trials and 180 d for field trials, cranial tissue samples were taken for spore enumeration (field and laboratory trials) and histological analyses (laboratory only). Clinical signs of disease, including whirling behavior, blacktail, and skeletal deformities, were recorded for each fish in the laboratory trial at the terminal sampling. No clinical evidence of disease was noted among fish in the field trials. Clinical signs were noted among all strains in the laboratory trials at both exposure levels, and these signs were consistently greatest for the Mount Lassen strain. Whirling and skeletal deformities were more evident in the steelhead than in the Cayuga Lake rainbow trout; blacktail was more common in the Cayuga Lake fish. In both field and laboratory trials, spore counts were significantly higher for Cayuga Lake rainbow trout than in steelhead. In laboratory trials, moderate to marked cranial tissue lesions predominated in all three strains.

  9. Colonization of a marker and field strain of Salmonella enteritidis and a marker strain of Salmonella typhimurium in vancomycin-pretreated and nonpretreated laying hens.

    PubMed

    Hannah, J F; Wilson, J L; Cox, N A; Richardson, L J; Cason, J A; Bourassa, D V; Buhr, R J

    2011-12-01

    This study was conducted to evaluate the influence of a vancomycin pretreatment on the ability of marker (nalidixic-acid resistant) Salmonella Enteritidis (SE(M)), field Salmonella Enteritidis (SE(E)), and marker Salmonella Typhimurium (ST(M)) strains to colonize within the intestinal and reproductive tracts and translocate to other organs of leghorn laying hens. In each of three trials, caged laying hens (76, 26, and 33 wk ofage) were divided into six groups designated to receive SE(M), SE(F), or ST(M), and half were pretreated with vancomycin (n = 11-12 hens). Vancomycin-treated hens received 10 mg vancomycin in saline/kilogram body weight orally for 5 days to inhibit Gram-positive bacteria within the intestines. On Day 6, all hens were concurrently challenged by oral, intravaginal, and intracolonal routes with Salmonella and placed into separate floor chambers by Salmonella strain. Two weeks postinoculation, all hens were euthanatized and the ceca, spleen, liver/gall bladder (LGB), upper (URT), and lower (LRT) reproductive tracts, and ovarian follicles were aseptically collected, and analyzed for Salmonella. Results did not differ for the three hen's ages and were therefore combined. The vancomycin pretreatment also had no significant effect on the colonization ability of SE(M), SE(F) or ST(M), and therefore results were combined within Salmonella strain. The marker strain of Salmonella Enteritidis was recovered from 21% of ceca, 4% of LGB, 9% of LRT, and 17% of the fecal samples. The field strain of Salmonella Enteritidis was recovered from 88% of ceca, 96% of spleen, 92% of LGB, 30% of LRT, 4% of URT, 13% of follicle, and 42% of the fecal samples. The marker strain of Salmonella Typhimurium was recovered from 100% of ceca, 74% of spleen, 91% of LGB, 30% of LRT, 9% of URT, 9% of follicle, and 100% of the fecal samples. Among ceca, spleen, LGB, and fecal samples, SE(F) and ST(M) colonization was significantly greater than SE(M) colonization. Overall prevalence

  10. Effect of residual strain in Fe-based amorphous alloys on field induced magnetic anisotropy and domain structure

    NASA Astrophysics Data System (ADS)

    Azuma, Daichi; Hasegawa, Ryusuke; Saito, Shin; Takahashi, Migaku

    2013-05-01

    Field induced magnetic anisotropy in two Fe-based amorphous alloys with different saturation induction levels (1.56 T and 1.64 T) was investigated by varying magnetic field strength and annealing temperature and domain images were taken on these samples. Residual strain was evaluated by measuring coercivities of the materials after stress-relief annealing. These results are discussed, clarifying the difference between the two Fe-based amorphous alloys.

  11. Hamiltonian bifurcation theory for a rotating flow subject to elliptic straining field

    NASA Astrophysics Data System (ADS)

    Fukumoto, Y.; Mie, Y.

    2013-07-01

    A weakly nonlinear stability theory is developed for a rotating flow confined in a cylinder of elliptic cross-section. The straining field associated with elliptic deformation of the cross-section breaks the SO(2)-symmetry of the basic flow and amplifies a pair of Kelvin waves whose azimuthal wavenumbers are separated by 2, being referred to as the Moore-Saffman-Tsai-Widnall (MSTW) instability. The Eulerian approach is unable to fully determine the mean flow induced by nonlinear interaction of the Kelvin waves. We establish a general framework for deriving the mean flow by a restriction to isovortical disturbances with use of the Lagrangian variables and put it on the ground of the generalized Lagrangian-mean theory. The resulting formula reveals enhancement of mass transport in regions dominated by the vorticity of the basic flow. With the mean flow at hand, we derive unambiguously the weakly nonlinear amplitude equations to third order for a nonstationary mode. By an appropriate normalization of the amplitude, the resulting equations are made Hamiltonian systems of four degrees of freedom, possibly with three first integrals identifiable as the wave energy and the mean flow.

  12. Tuning Magnetism and Electronic Phase Transitions by Strain and Electric Field in Zigzag MoS2 Nanoribbons

    NASA Astrophysics Data System (ADS)

    Kou, Liangzhi

    2013-03-01

    Effective modulation of physical properties via external control may open various potential nanoelectronic applications of single-layer MoS2 nanoribbons (MoS2NRs). We show by first-principles calculations that the magnetic and electronic properties of zigzag MoS2NRs exhibit sensitive response to applied strain and electric field. Tensile strain in the zigzag direction produces reversible modulation of magnetic moments and electronic phase transitions among metallic, half-metallic, and semiconducting states, which stem from the energy-level shifts induced by an internal electric polarization and the competing covalent/ionic interactions. A simultaneously applied electric field further enhances or suppresses the strain-induced modulations depending on the direction of the electric field relative to the internal polarization. These findings suggest a robust and efficient approach to modulating the properties of MoS2NRs by a combination of strain engineering and electric field tuning. L.K. acknowledges the financial support by the Alexander von Humboldt Foundation of Germany.

  13. Electric and magnetic fields and tumor progression. Final report

    SciTech Connect

    Keng, P.C.; Grota, L.J.; Michaelson, S.; Lu, S.T.

    1994-12-01

    This laboratory study has rigorously investigated two previously reported biological effects of 60-Hz electric and magnetic fields. The first effect involves nighttime suppression of melatonin synthesis in the pineal glands of rats exposed to high electric fields. The second concerns the increase in colony forming ability of human colon cancer cells exposed to 1.4-G magnetic fields. Neither effect was detected in the present study. A series of published laboratory studies on rats reported that 60-Hz electric fields at various field levels up to 130 kV/m suppress the nighttime synthesis of melatonin, a hormone produced by the pineal gland. Since melatonin is known to modulate the immune system and may inhibit cancer cell activity, changes in physiological levels of melatonin may have significant health consequences. In the repeat experiments, field exposure did not alter nighttime levels of melatonin or enzyme activities in the pineal gland. A small but statistically significant reduction of about 20% in serum melatonin was seen in exposed animals. Pineal melatonin was also unaffected by the presence of red light as a cofactor with field exposure or by time-shifting the daily field exposure period. Another study reported that 60-Hz magnetic fields can affect the colony forming ability of human cancer cells after exposure in a culture medium. In the repeat experiments, field exposure did not alter the colony forming ability of human Colo 205 cells in two different cell concentrations at plating or in two different incubation conditions. Field exposure also did not affect cell cycling in any of the four cell lines tested.

  14. Variation in susceptibility of field strains of three stored grain insect species to spinosad and chlorpyrifos-methyl plus deltamethrin on hard red winter wheat.

    PubMed

    Sehgal, Blossom; Subramanyam, Bhadriraju; Arthur, Frank H; Gill, Bikram S

    2013-08-01

    Spinosad and chlorpyrifos-methyl plus deltamethrin efficacy at labeled rates on hard red winter wheat were evaluated against 11 field strains of the red flour beetle, Tribolium castaneum (Herbst); six strains of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.); and two strains of the lesser grain borer, Rhyzopertha dominica (F.), collected mostly from farm-stored grain in Kansas. Adults were exposed to wheat treated with spinosad at 1 mg (active ingredient)/kg or chlorpyrifos-methyl plus deltamethrin at three plus 0.5 mg (active ingredient)/kg. Adult mortality was assessed after 7 and 14 d and progeny production after 42 d. Spinosad did not provide complete mortality or progeny suppression of T. castaneum and O. surinamensis field strains, but was effective against R. dominica strains. Chlorpyrifos-methyl plus deltamethrin produced complete mortality and progeny suppression of field strains all three species. The two least susceptible T. castaneum and O. surinamensis strains and the two R. dominica strains were chosen for dose-response tests only with spinosad. The LD99 values for T. castaneum and R. dominica field strains were similar to that of the corresponding laboratory strains. Corresponding values for the two O. sturinamensis field strains were significantly greater (approximately 6 times) than the laboratory strain. The effective dose for progeny reduction (ED99) of only one R. dominica field strain was significantly greater (approximately 2 times) than the laboratory strain. The baseline susceptibility data of field strains of three insect species to spinosad will be useful for monitoring resistance development when this product is commercially released as a grain protectant.

  15. Self-reported sleep quality, strain and health in relation to perceived working conditions in females.

    PubMed

    Edéll-Gustafsson, Ulla M; Kritz, Eivor I K; Bogren, I Kristina

    2002-06-01

    Self-reported sleep quality, strain and health in relation to perceived working conditions in females The aims of this study were to examine self-reported sleep quality, perceived strain and health in relation to working conditions; the prevalence and severity of sleep disturbances and daytime distress arising from poor sleep in women on different work shifts. Furthermore, to see whether females with gastrointestinal symptoms, joint-, back- or muscle-pain and who are dissatisfied with working hours differ with regard to the above aspects. Finally, degree of strain-related symptoms and sleep difficulties were tested as predictors of sleep quality and general health outcome. Important research questions are whether registered nurses and those on rotating work shifts have greater sleep problems than others. A total of 156 females, aged 20-59 years, working at three different casualty departments, answered structured questionnaires. The results showed a persistently high rate of psycho-physiological long-term effects of stress related to working conditions. Thirty-four per cent were dissatisfied with their working hours, and exhibited significantly more mental strain, fatigue/excessive tiredness and inability to relax after work because of involuntary thoughts, in relation to working conditions than others did. Sixty-two females (39.7%) complained of insufficient sleep. The sleep quality outcome was significantly predicted by difficulty falling asleep (odds ratio 8.4), difficulty in falling asleep after nocturnal awakening (odds ratio 3.4) and perceived exhaustion (odds ratio 2.6). Females suffering from gastrointestinal symptoms and joint-, back- and muscle symptoms for several days in a week or even everyday were especially sensitive to worse sleep quality. Independent of work shifts, registered nurses exhibited a higher degree of mental strain and prolonged recovery in comparison with others. In conclusions, sleep initiation difficulties, troubled sleep and

  16. Estimation of a Time-Dependent Strain Rate Field in Southern California Using Continuous GPS Stations in the SCIGN Network.

    NASA Astrophysics Data System (ADS)

    Hernandez, D.; Holt, W. E.; Bennett, R. A.; Li, C.; Dimitrova, L. L.; Haines, A. J.

    2005-12-01

    Advancements in the recognition of fine-scale deformation fluctuations have prompted a great deal of attention to be focused on identifying and characterizing transient strain phenomena. We have developed a tool for recognizing strain rate transients as well as for quantifying the magnitude and style of their temporal and spatial variations. Using time-varying velocity estimates for continuous GPS station data from the Southern California Integrated GPS Network (SCIGN) for the time period between October 1999 and February 2004 [Li et al., 2005]. We determine time-averaged velocity values in 0.05 year epochs for each continuous velocity series. For each velocity field solution we determine a self-consistent model velocity gradient tensor field solution for the region using bi-cubic Bessel interpolation of the GPS velocity vectors. For each epoch solution we plot dilatation strain rates, shear strain rates, and the rotation rates. We also investigate the departures of the model strain rate field and velocity field from a master solution, obtained from a time-averaged solution for the period 1999-2004, as well as estimating the departures of the time variable velocity gradient tensor field from other master solutions, including models that incorporate plate motion constraints and Quaternary fault data. By combining the epoch solution plots, we create movies that allow us to view the spatial and temporal changes in the dilation and shear strain rate field in southern California. In the present solution several time-dependent changes are noteworthy. The Eastern California Shear Zone (ECSZ) region, immediately following the October 1999 Hector Mine earthquake, shows a significant spatial change of relatively high shear strain rate that increases from the immediate area of the earthquake to an area that almost spans the entire ECSZ from east to west. Also following the Hector Mine event, there is a strain rate corridor that extends through the Pinto Mt. fault connecting

  17. Geodetic Monitoring of The Strain Evolution Field During The July - August 2001 Mt. Etna Eruption

    NASA Astrophysics Data System (ADS)

    Puglisi, G.; Etna01-Geo Team

    Since the beginning of the 2001 Etna eruption, EDM and GPS measurements have been carried out to monitor the evolution of the ground deformation pattern of the volcano during the particular period of activity. The ground deformation pattern pre- ceding the eruption was known thanks to previous EDM and GPS surveys carried out and completed just few days before the onset of the eruption. During the period of activity, EDM measurements have been carried out daily on the uppermost part of the southern and northeastern trilateration networks in order to monitor the strain of the areas surrounding the eruptive fractures. These surveys allowed following the evolu- tion of the strain field since the beginning of the seismic swarm preceding the opening of the eruptive fracture system. Most of the ground deformation has been observed during the very first days of the eruption. Starting from the last days of the activity, the three EDM networks located on the NE, SW and S flanks of the volcano have been completely measured to fix the ground deformation pattern caused by the eruption. During the opening of the fracture system, the N-S GPS profile (17 stations), starting from the NE Rift to the Rifugio Sapienza area, has been measured together with a few GPS stations on the upper part of the volcano. The comparison of these measurements with the previous ones carried out the day before the seismic swarm, depicts a strong ground deformation pattern in good agreement with the dynamics of the intrusion. Later, several measurements have been carried out also during the eruption, on part of the N-S profile (12 stations), from the NE rift to the Piano del Lago area, very near the upper part of the eruptive fracture, because some of the southernmost stations were covered by the lava flows during the first days of the eruption. GPS sessions have been also carried out almost daily on an E-W profile, consisting of 16 stations and cross- ing the Rifugio Sapienza and the 1989 fracture

  18. Development, validation and field evaluation of a quantitative real-time PCR able to differentiate between field Mycoplasma synoviae and the MS-H-live vaccine strain.

    PubMed

    Dijkman, R; Feberwee, A; Landman, W J M

    2017-08-01

    A quantitative PCR (qPCR) able to differentiate between field Mycoplasma synoviae and MS-H vaccine strain was developed, validated and evaluated. It was developed using nucleotide differences in the obg gene. Analytical specificity and sensitivity assessed using DNA from 194 M. synoviae field samples, three different batches of MS-H vaccine and from 43 samples representing four other avian Mycoplasma species proved to be 100%. The detection limit for field M. synoviae and MS-H vaccine strain was 10(2-3) and 10(2) colony-forming units PCR equivalents/g trachea mucus, respectively. The qPCR was able to detect both, field M. synoviae and MS-H vaccine strain in ratios of 1:100 determined both using spiked and field samples. One hundred and twenty samples from M. synoviae-infected non-vaccinated birds, 110 samples from M. synoviae-vaccinated birds from a bird experiment and 224 samples from M. synoviae negative (serology and PCR) birds were used to determine the relative sensitivity and specificity using a previously described M. synoviae PCR as reference. The relative sensitivity and specificity for field M. synoviae were 95.0% and 99.6%, respectively, and 94.6% and 100% for the MS-H-live vaccine, respectively. Field validation and confirmation by multi locus sequence typing revealed that the qPCR correctly distinguished between MS-H and field M. synoviae. Evaluation of the differentiating M. synoviae qPCR in three commercial flocks suggested transmission of MS-H-live vaccine from vaccinated to non-vaccinated flocks at the same farm. Furthermore, it showed evidence for the colonization with field M. synoviae in MS-H-vaccinated flocks.

  19. Full-field dynamic displacement and strain measurement using pulsed and high-speed 3D image correlation photogrammetry

    NASA Astrophysics Data System (ADS)

    Schmidt, Timothy; Tyson, John; Galanulis, Konstantin

    2004-02-01

    3D image correlation is a robust method for measuring full-field displacements and strains using a calibrated pair of video cameras. Underlying principles and benefits are reviewed, and the method is compared to both 3D ESPI and 2D image correlation. Several applications combining image correlation photogrammetry with stroboscopic illumination and/or high-speed video cameras are presented. Operational strains in ionic polymeric muscle samples and electro-restrictive actuators are determined. The use of short-duration white light pulses to study automobile tires on road wheels at speeds up to 150 miles per hour is demonstrated. Initial work measuring strains on an 18" flywheel in a spin pit at up to 35,000 rpm is described. A notched rubber dogbone sample is pulled to failure at 125% strain in 38 milliseconds, and hundreds of full-field strain maps are captured. This paper includes discussion of sample preparation methods and special lighting systems, including pulsed arc lamps and pulsed lasers. A matrix of capability using available high speed cameras is included.

  20. Measurement of high temperature full-field strain up to 2000 °C using digital image correlation

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Xu, Chenghai; Jin, Hua; Meng, Songhe; Zhang, Yumin; Xie, Weihua

    2017-03-01

    Understanding the deformation and strain at elevated temperature is a critical factor for the stability of aerodynamic shape, and an important consideration for the thermal protection system design. However, accurate measurement of deformation and strain at high temperatures is a challenge. Here, we present a measurement study for full-field strain mapping up to 2000 °C using digital image correlation (DIC) method, which mainly depends on the quality of speckle patterns on the specimen surface. In our study, the strain values are analyzed by DIC method while specimens are heated using a large electric current. Improvements in filtering and speckling allow the measured temperatures using this method to reach 2000 °C. We confirmed the validity of this method by comparison of measured Young’s modulus values with reference data for Inconel 718 Ni-based superalloy and graphite at different temperatures. Additionally, the full-field strain and Young’s modulus were demonstrated for a carbon fiber-reinforced carbon (C/C) composite uniaxial tensile specimen at 2000 °C.

  1. Stubborn Disease in Iran: Diversity of Spiroplasma citri Strains in Circulifer haematoceps Leafhoppers Collected in Sesame Fields in Fars Province.

    PubMed

    Zarei, Zahra; Salehi, Mohammad; Azami, Zabihallah; Salari, Khadijeh; Béven, Laure

    2017-02-01

    Spiroplasma citri is a bacterial pathogen responsible for the economically important citrus stubborn disease. Sesame and citrus seeds serve as hosts for both S. citri and its leafhopper vector Circulifer haematoceps. To evaluate whether sesame could act as a reservoir for citrus-infecting strains or not, the genetic diversity among S. citri strains found in leafhoppers collected in citrus and citrus-free sesame fields was investigated. Among 26 periwinkle plants exposed to the collected C. haematoceps leafhoppers, 12 plants developed typical stubborn symptoms. All symptomatic periwinkles were polymerase chain reaction positive using S. citri-specific primer pairs targeting the spiralin and P89 genes. Phylogenetic trees based on spiralin gene sequence analysis indicated that the novel field-collected strains clustered with those belonging to two formerly defined S. citri groups (groups 6 and 1). In addition, our results strongly suggest that group 1 strains could be transmitted from sesame-infected plants to citrus trees by C. haematoceps, while group 6 strains may not infect citrus trees.

  2. Population Genetic Structure of Listeria monocytogenes Strains as Determined by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing

    PubMed Central

    Henri, Clémentine; Félix, Benjamin; Guillier, Laurent; Leekitcharoenphon, Pimlapas; Michelon, Damien; Mariet, Jean-François; Aarestrup, Frank M.; Mistou, Michel-Yves; Hendriksen, René S.

    2016-01-01

    ABSTRACT Listeria monocytogenes is a ubiquitous bacterium that may cause the foodborne illness listeriosis. Only a small amount of data about the population genetic structure of strains isolated from food is available. This study aimed to provide an accurate view of the L. monocytogenes food strain population in France. From 1999 to 2014, 1,894 L. monocytogenes strains were isolated from food at the French National Reference Laboratory for L. monocytogenes and classified according to the five risk food matrices defined by the European Food Safety Authority (EFSA). A total of 396 strains were selected on the basis of different pulsed-field gel electrophoresis (PFGE) clusters, serotypes, and strain origins and typed by multilocus sequence typing (MLST), and the MLST results were supplemented with MLST data available from Institut Pasteur, representing human and additional food strains from France. The distribution of sequence types (STs) was compared between food and clinical strains on a panel of 675 strains. High congruence between PFGE and MLST was found. Out of 73 PFGE clusters, the two most prevalent corresponded to ST9 and ST121. Using original statistical analysis, we demonstrated that (i) there was not a clear association between ST9 and ST121 and the food matrices, (ii) serotype IIc, ST8, and ST4 were associated with meat products, and (iii) ST13 was associated with dairy products. Of the two major STs, ST121 was the ST that included the fewest clinical strains, which might indicate lower virulence. This observation may be directly relevant for refining risk analysis models for the better management of food safety. IMPORTANCE This study showed a very useful backward compatibility between PFGE and MLST for surveillance. The results enabled better understanding of the population structure of L. monocytogenes strains isolated from food and management of the health risks associated with L. monocytogenes food strains. Moreover, this work provided an accurate view

  3. Population Genetic Structure of Listeria monocytogenes Strains as Determined by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing.

    PubMed

    Henri, Clémentine; Félix, Benjamin; Guillier, Laurent; Leekitcharoenphon, Pimlapas; Michelon, Damien; Mariet, Jean-François; Aarestrup, Frank M; Mistou, Michel-Yves; Hendriksen, René S; Roussel, Sophie

    2016-09-15

    Listeria monocytogenes is a ubiquitous bacterium that may cause the foodborne illness listeriosis. Only a small amount of data about the population genetic structure of strains isolated from food is available. This study aimed to provide an accurate view of the L. monocytogenes food strain population in France. From 1999 to 2014, 1,894 L. monocytogenes strains were isolated from food at the French National Reference Laboratory for L. monocytogenes and classified according to the five risk food matrices defined by the European Food Safety Authority (EFSA). A total of 396 strains were selected on the basis of different pulsed-field gel electrophoresis (PFGE) clusters, serotypes, and strain origins and typed by multilocus sequence typing (MLST), and the MLST results were supplemented with MLST data available from Institut Pasteur, representing human and additional food strains from France. The distribution of sequence types (STs) was compared between food and clinical strains on a panel of 675 strains. High congruence between PFGE and MLST was found. Out of 73 PFGE clusters, the two most prevalent corresponded to ST9 and ST121. Using original statistical analysis, we demonstrated that (i) there was not a clear association between ST9 and ST121 and the food matrices, (ii) serotype IIc, ST8, and ST4 were associated with meat products, and (iii) ST13 was associated with dairy products. Of the two major STs, ST121 was the ST that included the fewest clinical strains, which might indicate lower virulence. This observation may be directly relevant for refining risk analysis models for the better management of food safety. This study showed a very useful backward compatibility between PFGE and MLST for surveillance. The results enabled better understanding of the population structure of L. monocytogenes strains isolated from food and management of the health risks associated with L. monocytogenes food strains. Moreover, this work provided an accurate view of L. monocytogenes

  4. Full-Field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.

    2008-01-01

    Recent advancements in braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape out of triaxial braided composite materials. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A more detailed investigation of deformation and failure processes in large-unit-cell-size triaxial braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. This report presents some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12- and 24-k yarns and a 0 /+60 /-60 triaxial braid architecture. Local deformation and failure within fiber bundles was observed and correlations were made between these local failures and global composite deformation and strength.

  5. Field monitoring of the ice load of an icebreaker propeller blade using fiber optic strain gauges

    NASA Astrophysics Data System (ADS)

    Morin, Andre; Caron, Serge; Van Neste, Richard; Edgecombe, Merv H.

    1996-05-01

    Navigation in polar waters presents a formidable challenge to ships' propulsion systems as large ice pieces impinging on their propeller blades sometimes result in stresses exceeding the yield strength of the blade material. Damage to propellers is costly and can also spell disaster if a ship becomes disabled in a remote area. To prevent such situations, design practice must be improved and theoretical models of propeller/ice interaction must be validated against experimental data. The blade shape requires that the load be monitored at many locations in order to obtain an accurate picture of the stress and load distribution. Fiber optic sensors are ideally suited for such an application, owing to their small size, stability over time, immunity to electro-magnetic interference, resistance to corrosion and chemical attack by sea water and hydraulic oil. We report the full-scale instrumentation of an icebreaker propeller blade with 54 Fabry-Perot based fiber optic strain gauges and shaft-mounted electronics. The instrumentation design and installation procedures are described. Additional data gathered from the propulsion control system and the ship's navigation equipment is presented and the data fusion performed with underwater video imagery of the instrumented blade is also discussed. An overview of the noise-free data obtained during the Antarctic trials is given. We finally discuss the sensors behavior and long term response, presenting their applicability to smart structures.

  6. Pulsed-field gel electrophoresis typing, antibiotic resistance, and plasmid profiles of Escherichia coli strains isolated from foods.

    PubMed

    Uysal, Ahmet; Durak, Yusuf

    2012-11-01

    Bacterial contamination in foods and antimicrobial resistance levels of common pathogenic strains causing food-borne disease are important in human health. Thus, typing technologies are important tools to determine primary sources of bacterial contamination. In this study, 40 Escherichia coli strains isolated from 85 food samples were evaluated in terms of genetic diversity, susceptibility to certain antibiotics, and plasmid profiles. Pulsed-field gel electrophoresis was used to identify the genetic relations of E. coli isolates. It was determined that the 40 E. coli strains revealed 32 different pulsotypes represented by 6 subtypes. Antibiotic susceptibility tests conducted by using a disc diffusion method against 15 antibiotics showed that although the isolates revealed 14 different types of resistance profiles, the strains showed the greatest resistance to ampicillin (77.5%), followed by ticarcillin-clavulanic acid (30%), tetracycline (22.5%), and cephalothin (14.5%). Plasmid isolations studies of the strains conducted by the method of alkaline lysis revealed that 18 (45%) of 40 E. coli strains contain 31 different plasmid bands ranging between 64.4 and 1 kb. The results showed that PFGE was a powerful method in tracking sources of food contamination and that the antibiotic resistance levels of food isolates were high and should be monitored.

  7. Optical measurement of the dynamic strain field of a fan blade using a 3D scanning vibrometer

    NASA Astrophysics Data System (ADS)

    Vuye, C.; Vanlanduit, S.; Presezniak, F.; Steenackers, G.; Guillaume, P.

    2011-07-01

    Understanding the origin of the stress and strain distribution is crucial to increase the durability of components under dynamic loading. Numerical simulations based on finite element (FE) models help with this understanding but must be validated by real measured data. Updating the FE model using the measured data is often the next step in the design process. In this paper the recently developed 3D-scanning laser doppler vibrometer (3D-SLDV) is used to measure the 3D-displacement of a fan blade, which is then used to calculate the dynamic strain distributions. The measurement principle and experimental setup are discussed thoroughly. The experimental results are validated by using a FE model on the one hand and strain gage measurements on the other. It is shown that this technique is capable of measuring normal strain far below 1 microstrain. This technique has the potential to fill in the gap of accurately measuring small (full-field) normal and shear strains at both low and high frequencies, where other optical techniques (and strain gages) would certainly fail.

  8. Full-field dynamic strain prediction on a wind turbine using displacements of optical targets measured by stereophotogrammetry

    NASA Astrophysics Data System (ADS)

    Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter

    2015-10-01

    Health monitoring of rotating structures (e.g. wind turbines and helicopter blades) has historically been a challenge due to sensing and data transmission problems. Unfortunately mechanical failure in many structures initiates at components on or inside the structure where there is no sensor located to predict the failure. In this paper, a wind turbine was mounted with a semi-built-in configuration and was excited using a mechanical shaker. A series of optical targets was distributed along the blades and the fixture and the displacement of those targets during excitation was measured using a pair of high speed cameras. Measured displacements with three dimensional point tracking were transformed to all finite element degrees of freedom using a modal expansion algorithm. The expanded displacements were applied to the finite element model to predict the full-field dynamic strain on the surface of the structure as well as within the interior points. To validate the methodology of dynamic strain prediction, the predicted strain was compared to measured strain by using six mounted strain-gages. To verify if a simpler model of the turbine can be used for the expansion, the expansion process was performed both by using the modes of the entire turbine and modes of a single cantilever blade. The results indicate that the expansion approach can accurately predict the strain throughout the turbine blades from displacements measured by using stereophotogrammetry.

  9. Magnetic fabrics of diamagnetic rocks and the strain field associated with the Dead Sea Fault, northern Israel

    NASA Astrophysics Data System (ADS)

    Levi, Tsafrir; Weinberger, Ram

    2011-04-01

    In order to exploit the potential of AMS axes ( k1, k2, k3) and magnitudes as a tool to estimate the strain field around major faults, the AMS of calcite-bearing diamagnetic rocks that crop out next to the Dead Sea Fault (transform) (DSF) were measured. The calcite-bearing Bar Kokhba limestone contains magnetic fabrics due mainly to the diamagnetic phase, as indicated by the low iron content (<130 ppm), and strong negative susceptibilities of all the AMS principal axes. The magnetic fabrics are solely controlled by the alignment of c-axes of almost pure calcite crystals and help to assess the strain fields prevailing post-deposition and during the tectonic evolution of the DSF. Based on the AMS measurements of 146 diamagnetic samples as well as 65 paramagnetic samples, three groups of minimum k3 AMS axes are defined: (1) ˜NNE-plunging axis; (2) ˜NW-SE axis; and (3) ˜E-W axis. The latter two groups of k3 axes are aligned sub-parallel to Neogene to Pleistocene finite-strain axes inferred from meso-scale structures (i.e., folds, faults and veins) next to the DSF. This indicates that k3 axes of diamagnetic rocks can be excellent proxies for strain field directions around major faults. Differences in the degree of anisotropy P' (up to ˜2%) and in susceptibility difference Δ k (up to ˜0.2) of the diamagnetic rocks are related to differences in strain magnitudes. Based on the proximity of the studied outcrops to the fault traces, the values of these variables reflect the stored inelastic strain within the calcite matrix due to repeated faulting activity.

  10. Persistent infections of a field strain of rabies virus in murine neuroblastoma (NA-C1300) cell cultures.

    PubMed Central

    Webster, W A; Charlton, K M; Casey, G A

    1989-01-01

    Rabies virus from the brain of a striped skunk (Mephitis mephitis) from Ontario was inoculated into murine neuroblastoma (NA-C1300) cell cultures. These cultures were incubated and the cells were subcultured every three to four days. The presence of viral antigen in the cell cultures was monitored by direct immunofluorescent staining and in the culture fluids by titration in either baby hamster kidney (BHK/C13) or NA cells or in experimental mice. The virus-infected NA cultures evolved from an initial high viral concentration in supernatant fluid through a period of decreasing titers of infectious virus in the supernatant fluids to a final phase where no infectious virus has been found following cell culture and animal inoculation methods attempted although the persistently infected cells remained 95-100% viral nucleocapsid antigen-positive. Possible mechanisms involved in the perpetuation of this infection are discussed. This is the first report of a persistent infection of cell cultures by a field strain of rabies virus. PMID:2590871

  11. Effects of vertical electric field and compressive strain on electronic properties of bilayer ZrS2

    NASA Astrophysics Data System (ADS)

    Shang, Jimin; Huang, Le; Wei, Zhongming

    2017-03-01

    Using first-principles calculations, including Grimme D2 method for van der Waals interactions, we investigate the tuning electronic properties of bilayer zirconium disulfides (ZrS2) subjected to vertical electric field and normal compressive strain. The band gap of ZrS2 bilayer can be flexibly tuned by vertical external electric field. Due to the Stark effect, at critical electric fields about 1.4 V/Å, semiconducting-metallic transition presents. In addition, our results also demonstrated that the compressive strain has an important impact on the electronic properties of ZrS2 bilayer sheet. The widely tunable band gaps confirm possibilities for its applications in electronics and optoelectronics. Project support by the CAS/SAFEA International Partnership Program for Creative Research Teams and the Basic and Frontier Technology Research of Henan (No. 142300410244).

  12. [Production of a vaccine against enterotoxemia from Clostridium perfringens strains isolated in the field].

    PubMed

    Cherfaoui, S; Kadra, B

    1992-01-01

    We have isolated eight strains of C. perfringens from cases of enterotoxaemia. Five of these strains have revealed themselves toxic with respective types (type "A":2, type "C":2, type "D":1). In order to produce anti-enterotoxaemia vaccine, we have proceeded at the cultivation in fermenter of isolated strains and reference strains CWA 35, CWC and CWD AF. At the end of fermentation, we have evaluated the two following parameters: obtained biomass, and toxin titers. With the two classes of strains we reached an important biomass but toxins titers relatively weak comparatively to that which is usually required. It will be necessary then, to demonstrate the immunogen value of the produced vaccines by testing their efficacity.

  13. Improved Newton-Raphson digital image correlation method for full-field displacement and strain calculation.

    PubMed

    Cofaru, Corneliu; Philips, Wilfried; Van Paepegem, Wim

    2010-11-20

    The two-dimensional in-plane displacement and strain calculation problem through digital image processing methods has been studied extensively in the past three decades. Out of the various algorithms developed, the Newton-Raphson partial differential correction method performs the best quality wise and is the most widely used in practical applications despite its higher computational cost. The work presented in this paper improves the original algorithm by including adaptive spatial regularization in the minimization process used to obtain the motion data. Results indicate improvements in the strain accuracy for both small and large strains. The improvements become even more significant when employing small displacement and strain window sizes, making the new method highly suitable for situations where the underlying strain data presents both slow and fast spatial variations or contains highly localized discontinuities.

  14. Evaluation of a New Entomopathogenic Strain of Beauveria bassiana and a New Field Delivery Method against Solenopsis invicta.

    PubMed

    Li, Jun; Guo, Qiang; Lin, Miaofeng; Jiang, Lu; Ye, Jingwen; Chen, Dasong; Li, Zhigang; Dai, Jianqing; Han, Shichou

    2016-01-01

    Solenopsis invicta Buren is one of the most important pests in China, and control measures are mainly based on the use of synthetic pesticides, which may be inadequate and unsustainable. Hence, there is a growing interest in developing biological control alternatives for managing S. invicta, such as the use of entomopathogenic fungi. To facilitate the commercialization of entomopathogenic fungi against S. invicta, 10 Beauveria bassiana isolates originating from different hosts were tested for virulence in laboratory bioassays, and the most pathogenic strain, ZGNKY-5, was tested in field studies using an improved pathogen delivery system. The cumulative mortality rate reached 93.40% at 1×108 mL-1 conidia after 504 h. The germination and invasion of the spores were observed under a scanning electron microscope, and several conidia adhered to the cuticle of S. invicta after 2 h. Furthermore, the germ tubes of the conidia oriented toward the cuticle after 48 h, and the mycelium colonized the entire body after 96 h. Based on the efficacy observed in the laboratory trials, further experiments were performed with ZGNKY-5 strain to evaluate its utility in an injection control technology against S. invicta in the field. We found that three dosage treatments of ZGNKY-5 strain (500 mL, 750 mL, and 1,000 mL per nest) had significant control effects. Our results show that this strain of Beauveria bassiana and our control method were effective against S. invicta in both laboratory and field settings.

  15. Evaluation of a New Entomopathogenic Strain of Beauveria bassiana and a New Field Delivery Method against Solenopsis invicta

    PubMed Central

    Li, Jun; Guo, Qiang; Lin, Miaofeng; Jiang, Lu; Ye, Jingwen; Chen, Dasong; Li, Zhigang; Dai, Jianqing; Han, Shichou

    2016-01-01

    Solenopsis invicta Buren is one of the most important pests in China, and control measures are mainly based on the use of synthetic pesticides, which may be inadequate and unsustainable. Hence, there is a growing interest in developing biological control alternatives for managing S. invicta, such as the use of entomopathogenic fungi. To facilitate the commercialization of entomopathogenic fungi against S. invicta, 10 Beauveria bassiana isolates originating from different hosts were tested for virulence in laboratory bioassays, and the most pathogenic strain, ZGNKY-5, was tested in field studies using an improved pathogen delivery system. The cumulative mortality rate reached 93.40% at 1×108 mL-1 conidia after 504 h. The germination and invasion of the spores were observed under a scanning electron microscope, and several conidia adhered to the cuticle of S. invicta after 2 h. Furthermore, the germ tubes of the conidia oriented toward the cuticle after 48 h, and the mycelium colonized the entire body after 96 h. Based on the efficacy observed in the laboratory trials, further experiments were performed with ZGNKY-5 strain to evaluate its utility in an injection control technology against S. invicta in the field. We found that three dosage treatments of ZGNKY-5 strain (500 mL, 750 mL, and 1,000 mL per nest) had significant control effects. Our results show that this strain of Beauveria bassiana and our control method were effective against S. invicta in both laboratory and field settings. PMID:27341441

  16. 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.

  17. Small animal electric and magnetic field exposure systems. Final report

    SciTech Connect

    Patterson, R.C.; Dietrich, F.M.

    1993-10-01

    Laboratory evaluation of electric and magnetic fields (EMF) and cancer in animals requires exposure of relatively large numbers of animals, usually rats or mice, to 60-Hz fields under very well controlled conditions for periods of up to two years. This report describes two exposure systems, the first of which is based on modifications of an existing electric field exposure system to include magnetic field exposure capability. In this system, each module houses 576--768 mice, which can be exposed to electric field levels of up to 100 kV/m and magnetic field levels of up to 10 Gauss. When a module was operated at 10 Gauss, measured levels of noise and vibration fell substantially below the detection threshold for humans. Moreover, temperature rise in the coils did not exceed 12{degrees}C at the 10 Gauss level. Specifications and test results for the second system, which provides magnetic field exposure capability only, are similar, except that each module houses 624--780 mice. After installation of the second system at the West Los Angeles Veterans Medical Center in Los Angeles, California, additional results were obtained. This report provides a complete description of the engineering design, specifications, and test results for the completed systems.

  18. FIRST REPORT OF METALLO-β-LACTAMASES PRODUCING Enterobacter spp. STRAINS FROM VENEZUELA

    PubMed Central

    Martínez, Dianny; Rodulfo, Hectorina E.; Rodríguez, Lucy; Caña, Luisa E.; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; Donato, Marcos De

    2014-01-01

    Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of bla VIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed bla TEM-1, but only one showed bla CTX-M-15 gene, while no bla SHV was detected. PMID:24553611

  19. First report of metallo-β-lactamases producing Enterobacter spp. strains from Venezuela.

    PubMed

    Martínez, Dianny; Rodulfo, Hectorina E; Rodríguez, Lucy; Caña, Luisa E; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; De Donato, Marcos

    2014-01-01

    Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of blaVIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed blaTEM-1, but only one showed blaCTX-M-15 gene, while no blaSHV was detected.

  20. First report of fluazuron resistance in Rhipicephalus microplus: a field tick population resistant to six classes of acaricides.

    PubMed

    Reck, José; Klafke, Guilherme Marcondes; Webster, Anelise; Dall'Agnol, Bruno; Scheffer, Ramon; Souza, Ugo Araújo; Corassini, Vivian Bamberg; Vargas, Rafael; dos Santos, Julsan Silveira; Martins, João Ricardo de Souza

    2014-03-17

    The control of the cattle tick Rhipicephalus microplus is based mainly on the use of chemical acaricides, which has contributed to the emerging problem of selection of resistant tick populations. Currently, there are six main classes of acaricides commercially available in Brazil to control cattle ticks, with fluazuron, a tick growth regulator with acaricidal properties, being the only active ingredient with no previous reports of resistance. Ticks (designated the Jaguar strain) were collected in a beef cattle ranch located at Rio Grande do Sul state, Southern Brazil, after a complaint of fluazuron treatment failure. To characterise the resistance of this strain against acaricides, larval tests were performed and showed that the Jaguar strain was resistant to all of the drugs tested: cypermethrin (resistance ratio, RR=31.242), chlorpyriphos (RR=103.926), fipronil (RR=4.441), amitraz (RR=11.907) and ivermectin (3.081). A field trial was conducted to evaluate the efficacy of fluazuron treatment in heifers that had been experimentally infested with the Jaguar or a susceptible strain. Between 14 and 28 days after treatment, the average efficacy in cattle experimentally infested with the susceptible strain was 96%, while for the Jaguar strain the efficacy was zero. Additionally, the Jaguar strain response to fluazuron was evaluated in vitro using a modified adult immersion test (AIT) and the artificial feeding assay (AFA). With the AIT, 50 ppm of fluazuron inhibited 99% of larvae hatching in the susceptible strain (POA) and less than 50% in the Jaguar strain. Results of the AFA showed a larval hatching rate of 67% at 2.5 ppm of fluazuron with the Jaguar strain; conversely, only 3% of larvae of the susceptible strain hatched at the same fluazuron concentration. The results showed here demonstrated the first case of fluazuron resistance in R. microplus and the first tick population resistant to six classes of acaricides in Brazil.

  1. Finite element analysis of the plane strain crack-tip mechanical fields in pseudoelastic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Baxevanis, T.; Chemisky, Y.; Lagoudas, D. C.

    2012-09-01

    The plane strain mechanical fields near a stationary crack tip in a pseudoelastic shape memory alloy (SMA) are analyzed via the finite element method. The small scale transformation assumption is employed for the calculations using displacement boundary conditions on a circular region that encloses the stress-induced phase transformation zone. The constitutive law used adopts the classical rate-independent small strain flow theory for the evolution equations of both the transformation and plastic strains. Results on the size and shape of the stress-induced transformation and plastic zone formed near the stationary crack are obtained and a fracture toughness criterion based on the J-integral is discussed in view of the observed path-dependence of J. Moreover, the obtained results are discussed in relation to results for stationary cracks in conventional elastic-plastic materials.

  2. First report of two rapid-onset fatal infections caused by a newly emerging hypervirulent K. Pneumonia ST86 strain of serotype K2 in China.

    PubMed

    Zhang, Yibo; Sun, Jingyong; Mi, Chenrong; Li, Wenhui; Zhao, Shengyuan; Wang, Qun; Shi, Dake; Liu, Luo; Ding, Bingyu; Chang, Yung-Fu; Guo, Hongxiong; Guo, XiaoKui; Li, Qingtian; Zhu, Yongzhang

    2015-01-01

    Here, we present the first report of one suspected dead case and two confirmed rapid-onset fatal infections caused by a newly emerging hypervirulent Klebsiella pneumoniae ST86 strain of serotype K2. The three cases occurred in a surgery ward during 2013 in Shanghai, China. A combination of multilocus sequence typing, pulsed-field gel electrophoresis, phenotypic and PCR tests for detecting virulence factors (VFs) was used to identify the isolates as K2 ST86 strains with common VFs, including Aerobactin and rmpA. Furthermore, the two K2 ST86 strains additionally harbored a distinct VF kfu (responsible for iron uptake system), which commonly existed in invasive K1 strains only. Thus, the unusual presence of both K1 and K2 VFs in the lethal ST86 strain might further enhance its hypervirulence and cause rapid onset of a life-threatening infection. Nevertheless, despite the administration of a combined antibiotic treatment, these three patients all died within 24 h of acute onset, thereby highlighting that the importance of early diagnosis to determine whether the ST86 strains harbor key K2 VF and unusual K1 kfu and whether patients should receive a timely and targeted antibiotic therapy to prevent ST86 induced fatal pneumonia. Finally, even though these patients are clinically improved, keeping on with oral antibiotic treatment for additional 2-3 weeks will be also vital for successfully preventing hvKP reinfection or relapse.

  3. POPLITEUS STRAIN WITH CONCURRENT DELTOID LIGAMENT SPRAIN IN AN ELITE SOCCER ATHLETE: A CASE REPORT

    PubMed Central

    Beaumont, Josh; Tarnay, Lorena; Silvers, Holly

    2013-01-01

    Study Design: Case Report (Differential diagnosis) Background and Purpose: Differential diagnosis of knee pathology after trauma may be difficult when diagnosing an isolated popliteus strain and concurrent medial deltoid ligament sprain. Upon a thorough search of the published literature, the authors found no reports delineating a popliteus strain in professional soccer in the United States. The joints most affected by injury in soccer players are the knee and ankle joints. The purpose of this case report is to describe the presentation of and difficulties encountered in diagnosing a popliteus strain in a Major League Soccer athlete. Case Description: During an in-season away game, an outside defender was slide-tackled from behind when his right shank was caught in an externally rotated position underneath himself and the opposing player. The initial point of contact was made to the proximal third of the posterior right shank with an anteromedially directed force. The medial longitudinal arch of the foot was forced into a more midfoot pronated position and the subtalar joint was forced into eversion. Diagnosis: The athlete was diagnosed with a moderate strain of the right popliteus muscle with a concurrent medial deltoid ligament sprain of the right ankle. This mechanism of injury, pain with passive knee flexion and internal rotation during McMurray's test, pain with Garrick's Test and magnetic resonance imaging (MRI) study confirmed the diagnosis. The athlete returned to full ninety-minute game participation after an intensive 15-day rehabilitation program. Discussion: This case is unique because the injury manifested itself at multiple joints and specifically involved the popliteus muscle. The mechanism of injury can be associated with many other soft tissue injuries to the knee, and thus, may not lead the clinician initially to consider the diagnosis of a popliteus strain. Diagnosis of this entity may be difficult due to the possible shared attachment of the

  4. Two-Dimensional Strain Fields on the Cross-Section of the Human Patellofemoral Joint under Physiological Loading

    PubMed Central

    Guterl, Clare Canal; Gardner, Thomas R.; Rajan, Vikram; Ahmad, Christopher S.; Hung, Clark T.; Ateshian, Gerard A.

    2009-01-01

    The objective of this study was to provide a detailed experimental assessment of the two-dimensional cartilage strain distribution on the cross-section of the human patellofemoral joint (PFJ) subjected to physiological load magnitudes and rates. The medial side of six human PFJs sectioned along their mid-sagittal plane was loaded up to the equivalent of two body weights on a whole joint, and strain measurements obtained from digital image correlation are reported at 0.5s. Normal strains tangential to the articular surface and shear strains in the plane of the cross-section showed consistent patterns among all specimens, whereas normal strains perpendicular to the articular surface exhibited some variability that may be attributed to subject-specific variations in material properties through the depth of the articular layers. Elevated tensile and compressive principal normal strains were observed near the articular surface, around the center of the contact region, with additional locations of elevated compressive strains occurring at the bone-cartilage interface. Under an average contact stress of ∼3.3 MPa, the peak compressive principal normal strains for the patella and femur averaged -0.158 ± 0.072 and -0.118 ± 0.051 respectively, magnitudes that are significantly greater than the relative changes in cartilage thickness, -0.090 ± 0.030 and -0.072 ± 0.038 (p < 0.005). These experimental results provide a detailed description of the manner by which human PFJ articular layers deform in situ under physiological load conditions. PMID:19433326

  5. Microstructure, Magnetism and Magnetic Field Induced-Strain in Er-Doped Co-Ni-Al Polycrystalline Alloy

    NASA Astrophysics Data System (ADS)

    Ju, Jia; Lou, Shuting; Yan, Chen; Yang, Liu; Li, Tao; Hao, Shuai; Wang, Xingyi; Liu, Huan

    2017-04-01

    A large magnetic field-induced strain (MFIS) was discovered in single-crystal alloys, whereas it is proven difficult for such apparent strain values to be obtained in polycrystalline alloys. In order for an apparent strain discovery to occur, the polycrystalline Co-Ni-Al system was doped by 0-1 at.% of Er and the effects of doping on microstructure, magnetism and MFIS were studied via scanning electron microscopy, x-ray diffraction, transmission electron microscopy and vibrating sample magnetometer in the present work. The microstructure of the alloy was a dual-phase microstructure, including the matrix and the γ phase. Following the Er doping, the γ phase was continuously coarsened, forming a network of precipitates surrounding the grains. Also, a Co-Er-rich intermetallic compound was formed in the Co-rich γ phase when the Er content exceeded 0.1 at.%. The martensitic transformation temperature has a decreasing tendency during the Er being doped from 0 at.% to 1 at.% and the martensitic structure of the sample is of the L10 type, forming twin grains in the (111) twinning plane. On the contrary, the magnetic properties were improved by Er doping, especially saturation magnetization and magneto-crystalline anisotropy constantly increased to 60.45 emu/g and 3.13 × 106 erg/cm3 when the Er content reached 1 at.%, respectively. Also, the strain recovery ratio ( R s) of Co-Ni-Al-Er alloys can be enhanced by thermo-mechanical cycles and Er doping. At 5% of the total strain, the R s value exceeded 83% following thermo-mechanical cycles when the Er doping was 1 at.%. The strain in the applied magnetic field was increased by Er doping and an excess of 140 ppm of MFIS was obtained in the polycrystalline Co-Ni-Al-Er alloys.

  6. EFFECT OF STRAIN FIELD ON THRESHOLD DISPLACEMENT ENERGY OF TUNGSTEN STUDIED BY MOLECULAR DYNAMICS SIMULATION

    SciTech Connect

    Wang, D.; Gao, Ning; Setyawan, Wahyu; Kurtz, Richard J.; Gao, X.; He, W. H.

    2016-03-31

    The influence of hydrostatic strain on point defect formation energy and threshold displacement energy (Ed) in body-centered cubic (BCC) tungsten was studied with molecular dynamics simulations. Two different tungsten potentials (Fikar and Juslin) were used. The minimum Ed direction calculated with the Fikar-potential was <100>, but with the Juslin-potential it was <111>. The most stable self-interstitial (SIA) configuration was a <111>-crowdion for both potentials. The stable SIA configuration did not change with applied strain. Varying the strain from compression to tension increased the vacancy formation energy but decreased the SIA formation energy. The SIA formation energy changed more significantly than for a vacancy such that Ed decreased with applied strain from compression to tension.

  7. Annual Report for 2003 Wild Horse Research and Field Activities

    USGS Publications Warehouse

    Ransom, Jason; Singer, Francis J.; Zeigenfuss, Linda C.

    2004-01-01

    This report is meant to highlight the activities of the 2003 field season, as well as to provide a general overview of the data collected. More in-depth data analysis will be conducted following the conclusion of each I phase of the research project, and in many cases will not be possible until several seasons of data are collected.

  8. Anisotropy of magnetic susceptibility in diamagnetic limestones reveals deflection of the strain field near the Dead Sea Fault, northern Israel

    NASA Astrophysics Data System (ADS)

    Issachar, R.; Levi, T.; Marco, S.; Weinberger, R.

    2015-08-01

    To exploit the potential of anisotropy of magnetic susceptibility (AMS) as a tool to estimate the strain field around major faults, we measured the AMS of calcite-bearing diamagnetic rocks that crop out next to the Dead Sea Fault (DSF) in northern Israel. Through integrated magnetic and geochemical methods we found that the rocks are almost pure calcite rocks and therefore the magnetic fabric is primarily controlled by preferred crystallographic orientation (PCO) with the minimum principal AMS axes (k3) parallel to calcite c-axes. We applied a separation procedure in several samples with high Fe content in order to calculate the AMS anisotropy parameters and compare them to pure diamagnetic rocks. AARM, thermo-susceptibility curves and IRM were used to characterize the magnetic phases. We found that for Fe content below 500 ppm the AMS is mostly controlled by the diamagnetic phase and showed that differences in the degree of anisotropy P' up to 3% (P' = 1.005 to 1.023) and in anisotropy difference Δk (up to ~ 0.25 × 10- 6 SI) in diamagnetic rocks are related to differences of strain magnitudes. The spatial distribution of the magnetic fabrics indicates ~ N-S maximum shortening parallel to the strike of the Hula Western Border fault (HWBF), one of the main strands of the DSF in northern Israel. The anisotropy parameters suggest that the strain magnitudes increase eastward with the proximity to the HWBF. These results suggest that the strain field near the HWBF is locally deflected as a consequence of the DSF activity. In light of the "fault weakness" model and geological setting of the study area, we suggest that the area accommodates dominant transtension during the Pleistocene. The present study demonstrates the useful application of AMS measurements in "iron-free" limestones as recorders of the strain field near plate boundaries.

  9. Wild mouse open field behavior is embedded within the multidimensional data space spanned by laboratory inbred strains.

    PubMed

    Fonio, E; Benjamini, Y; Sakov, A; Golani, I

    2006-07-01

    The vast majority of studies on mouse behavior are performed on laboratory mouse strains (Mus laboratorius), while studies of wild-mouse behavior are relatively rare. An interesting question is the relationship between the phenotypes of M. laboratorius and the phenotypes of their wild ancestors. It is commonly believed, often in the absence of hard evidence, that the behavior of wild mice exceeds by far, in terms of repertoire richness, magnitude of variables and variability of behavioral measures, the behavior of the classical inbred strains. Having phenotyped the open field behavior (OF) of eight of the commonly used laboratory inbred strains, two wild-derived strains and a group of first-generation-in-captivity local wild mice (Mus musculus domesticus), we show that contrary to common belief, wild-mouse OF behavior is moderate, both in terms of end-point values and in terms of their variability, being embedded within the multidimensional data space spanned by laboratory inbred strains. The implication could be that whereas natural selection favors moderate locomotor behavior in wild mice, the inbreeding process tends to generate in mice, in some of the features, extreme and more variable behavior.

  10. Phase transition and electric field induced strain properties in Sm modified lead zirconate stannate titanate based antiferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Qingfeng; Yang, Tongqing; Zhang, Yangyang; Yao, Xi

    2013-06-01

    The effect of Sm addition on the crystal structures and electrical properties of Pb1-3x/2Smx(Zr0.63Sn0.26Ti0.11)O3 ceramics were investigated in this work. X-ray diffraction analysis showed that with increasing Sm content from 0.005 to 0.03, the phase structure of the specimens underwent transition from ferroelectric (FE) to antiferroelectric (AFE) state due to the substitution of Sm3+ with smaller ion radius for Pb2+ decreasing the tolerance factor of the ceramics. In addition, it was observed that with the improvement of Sm3+ content, the strain of the specimens first increased and then decreased, and the largest value of 0.735% was obtained in the sample with x = 0.015 near AFE/FE phase boundary at the measuring frequency 1 Hz. This is because the reversal of the domains, which produces the strain, is more consummate in this composition. Further, the strain at different frequencies was nearly the same at high electric field, which was attributed to that the electric field applied to the sample was so large that the reorientation of the domains could finish in all measuring frequencies. Both a high strain level and a relatively good frequency stability in the specimen with x = 0.015 make a potential candidate for actuators applications over a wide-frequency working range.

  11. First report of an OXA-48-producing multidrug-resistant Proteus mirabilis strain from Gaza, Palestine.

    PubMed

    Chen, Liang; Al Laham, Nahed; Chavda, Kalyan D; Mediavilla, Jose R; Jacobs, Michael R; Bonomo, Robert A; Kreiswirth, Barry N

    2015-07-01

    We report the first multidrug-resistant Proteus mirabilis strain producing the carbapenemase OXA-48 (Pm-OXA-48) isolated at Al-Shifa hospital in Gaza, Palestine. Draft genome sequencing of Pm-OXA-48 identified 16 antimicrobial resistance genes, encoding resistance to β-lactams, aminoglycosides, fluoroquinolones, phenicols, streptothricin, tetracycline, and trimethoprim-sulfamethoxazole. Complete sequencing of the bla(OXA-48)-harboring plasmid revealed that it is a 72 kb long IncL/M plasmid, harboring carbapenemase gene bla(OXA-48), extended spectrum β-lactamase gene bla(CTX-M-14), and aminoglycoside resistance genes strA, strB, and aph(3')-VIb.

  12. Surfactant-enhanced alkaline flooding field project. Annual report, Revision

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  13. Full-field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.

    2008-01-01

    Composite materials made with triaxial braid architecture and large tow size carbon fibers are beginning to be used in many applications, including composite aircraft and engine structures. Recent advancements in braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape. Although the large unit cell size of these materials is an advantage for manufacturing efficiency, the fiber architecture presents some challenges for materials characterization, design, and analysis. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A potential problem with using standard tests methods for these materials is that the unit cell size can be an unacceptably large fraction of the specimen dimensions. More detailed investigation of deformation and failure processes in large unit cell size triaxial braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. In recent years, commercial equipment has become available that enables digital image correlation to be used on a more routine basis for investigation of full field 3D deformation in materials and structures. In this paper, some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques are presented. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12 and 24 k yarns and a 0/+60/-60 triaxial braid architecture. Local deformation and failure within fiber bundles was observed, and this local failure had a significant effect on global stiffness and strength. The matrix material had a large effect on local damage initiation for the two matrix materials used in this investigation

  14. Resistance genes, phage types and pulsed field gel electrophoresis pulsotypes in Salmonella enterica strains from laying hen farms in southern Italy.

    PubMed

    Camarda, Antonio; Pugliese, Nicola; Pupillo, Antonia; Oliva, Marta; Circella, Elena; Dionisi, Anna Maria; Ricci, Antonia; Legretto, Marilisa; Caroli, Anna; Pazzani, Carlo

    2013-08-06

    Twenty-four Salmonella enterica isolates (13 serovar Enteritidis and 11 Typhimurium) isolated from 5,600 samples from intensive laying hen farms in Italy in 1998-2007 were characterized for antimicrobial resistance genes, pulsotype and phage type. Most of S. Typhimurium strains were pulsotype STYMXB.0147 (81.8%), phage type DT143 and resistant to sulfamethoxazole encoded by sul2. Two multidrug resistant (MDR) strains were identified. One strain, STYMXB.0061, was resistant to ampicillin (A), chloramphenicol (C), streptomycin (S), sulfamethoxazole (Su) and tetracycline (T) encoded by the Salmonella Genomic Island SGI1. The second MDR strain, STYMXB.0110, was resistant to SSuT encoded by sul1 and sul2, aadA1 and tet(C)-flanked by an IS26 element, respectively. The tet(C) gene has been reported to confer low levels of resistance and it has very rarely been detected in S. Typhimurium from poultry. In the current study, the MIC value (32 µg/mL) was consistent with the breakpoint (≥16 µg/mL) reported for Enterobacteriaceae. Most of the S. Enteritidis strains were resistant to Su (encoded by sul2). One MDR strain (ANxSSuT) was identified. With the exception of nalidixic acid (Nx), the resistances were respectively encoded by bla(TEM), strAB, sul2 and tet(A) harbored by an IncN conjugative plasmid. All isolates were pulsotype SENTXB.0001 with PT14b being the most prevalent identified phage type (57.1%). In Europe, SENTXB.0001 is the predominant PFGE profile from clinical cases and the identification of PT14b has steadily been on the increase since 2001. The findings presented in this study highlight the potential spread of S. Enteritidis phage types PT14b and S. Typhimurium DT143 in a field of particular relevance for zoonoses. Additional, the presence of resistance genes and genetic elements (conjugative plasmid and IS element) underlines the need to assess routinely studies in field, such as poultry farms, relevant fot the public health and suitable for the storage

  15. X-ray dynamical diffraction from single crystals with arbitrary shape and strain field: A universal approach to modeling

    NASA Astrophysics Data System (ADS)

    Yan, Hanfei; Li, Li

    2014-01-01

    The effects of dynamical diffraction in single crystals engender many unique diffraction phenomena that cannot be interpreted by the kinematical-diffraction theory, yet knowledge of them is vital to resolving a vast variety of scientific problems ranging from crystal optics to strain measurements in crystalline specimens. Although the fundamental dynamical-diffraction theory was established decades ago, modeling it remains a challenge in a general case wherein the crystal has complex boundaries and mixed diffraction geometries (Bragg or Laue). Here, we propose a universal approach for modeling x-ray dynamical diffraction from a single crystal with arbitrary shape and strain field that is based on the integral representation of the Takagi-Taupin equations. Using it, we can construct the solution iteratively via a converging series, independent of the diffraction geometry. Moreover, the integral equations offer additional insights into the diffraction physics that are not readily apparent in its differential counterparts. To demonstrate this approach, we studied the dynamical diffraction from a slab of single crystal with both Bragg and Laue diffraction excited on the entrance boundaries, a problem that is difficult to model by other methods. We also explored the mirage effect caused by the presence of a linear strain field and compared it to the Eikonal theory. Lastly, we derived a dynamical-diffraction equation correlating the structural properties of a particle to its far-field Bragg-diffraction pattern, shedding light on how dynamical diffraction affects these kinematical-diffraction-based inverse techniques for reconstructing the shape and the strain field.

  16. Symmetry Breaking and Fine Structure Splitting in Zincblende Quantum Dots: Atomistic Simulations of Long-Range Strain and Piezoelectric Field

    NASA Astrophysics Data System (ADS)

    Ahmed, Shaikh; Usman, Muhammad; Heitzinger, Clemens; Rahman, Rajib; Schliwa, Andrei; Klimeck, Gerhard

    2007-04-01

    Electrons and holes captured in self-assembled quantum dots (QDs) are subject to symmetry breaking that cannot be represented in with continuum material representations. Atomistic calculations reveal symmetry lowering due to effects of strain and piezo-electric fields. These effects are fundamentally based on the crystal topology in the quantum dots. This work studies these two competing effects and demonstrates the fine structure splitting that has been demonstrated experimentally can be attributed to the underlying atomistic structure of the quantum dots.

  17. Neural Network Prediction of Failure of Damaged Composite Pressure Vessels from Strain Field Data Acquired by a Computer Vision Method

    NASA Technical Reports Server (NTRS)

    Russell, Samuel S.; Lansing, Matthew D.

    1997-01-01

    This effort used a new and novel method of acquiring strains called Sub-pixel Digital Video Image Correlation (SDVIC) on impact damaged Kevlar/epoxy filament wound pressure vessels during a proof test. To predict the burst pressure, the hoop strain field distribution around the impact location from three vessels was used to train a neural network. The network was then tested on additional pressure vessels. Several variations on the network were tried. The best results were obtained using a single hidden layer. SDVIC is a fill-field non-contact computer vision technique which provides in-plane deformation and strain data over a load differential. This method was used to determine hoop and axial displacements, hoop and axial linear strains, the in-plane shear strains and rotations in the regions surrounding impact sites in filament wound pressure vessels (FWPV) during proof loading by internal pressurization. The relationship between these deformation measurement values and the remaining life of the pressure vessels, however, requires a complex theoretical model or numerical simulation. Both of these techniques are time consuming and complicated. Previous results using neural network methods had been successful in predicting the burst pressure for graphite/epoxy pressure vessels based upon acoustic emission (AE) measurements in similar tests. The neural network associates the character of the AE amplitude distribution, which depends upon the extent of impact damage, with the burst pressure. Similarly, higher amounts of impact damage are theorized to cause a higher amount of strain concentration in the damage effected zone at a given pressure and result in lower burst pressures. This relationship suggests that a neural network might be able to find an empirical relationship between the SDVIC strain field data and the burst pressure, analogous to the AE method, with greater speed and simplicity than theoretical or finite element modeling. The process of testing SDVIC

  18. Field persistence of the edible ectomycorrhizal fungus Lactarius deliciosus: effects of inoculation strain, initial colonization level, and site characteristics.

    PubMed

    Hortal, Sara; Pera, Joan; Parladé, Javier

    2009-03-01

    Pinus pinea plants were inoculated with different strains of the edible ectomycorrhizal fungus Lactarius deliciosus. The inoculated plants were established in six experimental plantations in two sites located in the Mediterranean area to determine the effect of the initial colonization level and the inoculated strain on fungal persistence in the field. Ectomycorrhizal root colonization was determined at transplantation time and monitored at different times from uprooted plants. Extraradical soil mycelium biomass was determined from soil samples by TaqMan(R) real-time polymerase chain reaction (PCR). The results obtained indicate that the field site played a decisive role in the persistence of L. deliciosus after outplanting. The initial colonization level and the selection of the suitable strain were also significant factors but their effect on the persistence and spread of L. deliciosus was conditioned by the physical-chemical and biotic characteristics of the plantation soil and, possibly, by their influence in root growth. Molecular techniques based on real-time PCR allowed a precise quantification of extraradical mycelium of L. deliciosus in the field. The technique is promising for non-destructive assessment of fungal persistence since soil mycelium may be a good indicator of root colonization. However, the accuracy of the technique will ultimately depend on the development of appropriate soil sampling methods because of the high variability observed.

  19. Symmetry-adapted calculations of strain and polarization fields in (111)-oriented zinc-blende quantum dots

    NASA Astrophysics Data System (ADS)

    Schulz, S.; Caro, M. A.; O'Reilly, E. P.; Marquardt, O.

    2011-09-01

    We present expressions for the elastic and first-order piezoelectric tensor in (111)-oriented III-V zinc-blende semiconductors. Moreover, an equation for the second-order piezoelectric polarization vector in these systems is derived. Together these expressions provide an efficient route to calculate built-in potentials and strain fields in (111)-oriented zinc-blende nanostructures. Our detailed analysis provides insight into the key parameters that modify strain and built-in fields in a (111)-oriented zinc-blende system compared to a conventional (001) structure. We show that the calculated strain field in a (111)-oriented quantum dot displays the correct C3v symmetry of the underlying crystal structure, even though we use a continuum-based approach and the quantum dot geometry is higher in symmetry than C3v, e.g., C∞v. This behavior originates from an in-plane angle dependence of certain elastic tensor components in the (111)-zinc-blende system. In addition, we compare the elastic and the first-order piezoelectric tensor of the (111)-zinc-blende systems with the corresponding quantities in a wurtzite structure and point out similarities and differences. This comparison provides, for example, insight into the sign of the shear piezoelectric coefficient e15 in the wurtzite system, which is still under debate in the literature. Our analysis indicates e15<0, in accordance with recent experimental and theoretical results.

  20. Near-field strain observations of the October 2013 Ruisui, Taiwan, earthquake: source parameters and limits of very short-term strain detection

    NASA Astrophysics Data System (ADS)

    Canitano, Alexandre; Hsu, Ya-Ju; Lee, Hsin-Ming; Linde, Alan T.; Sacks, Selwyn

    2015-08-01

    Volumetric strain changes associated with the October 2013 M w 6.2 Ruisui earthquake were recorded by a network made up with four borehole Sacks-Evertson dilatometers in eastern Taiwan. These instruments are located within 25-30 km of the seismic source providing also high-resolution near-field observations. Co-seismic offsets larger than a few 102 n ɛ were seen by most of the sensors. We relocated the 30 km × 30 km fault plane through a grid-search approach. The inferred fault parameters (217°, 48°, 49°) are in reasonable agreement with those resulting from the inversions of long-period seismic waves (209°, 59°, 50°) as well as from GPS data inversion (200°, 45°, 42°). Moreover, analysis of the 100-Hz sampling data 10 s before seismic radiations indicate no pre-seismic strain change emergent from the instrumental noise level (from 10 -2 to 10 -1 n ɛ). Such an observation sets limits on any precursory change in a nucleation area, taken to have dimensions of about 250-300 m, seconds before the mainshock. Thus, the upper limit of any pre-seismic moment is about 10 -5 % of the total seismic moment of the Ruisui earthquake.

  1. Simultaneous analysis of the nasal shedding kinetics of field and vaccine strains of Bordetella bronchiseptica.

    PubMed

    Iemura, R; Tsukatani, R; Micallef, M J; Taneno, A

    2009-12-26

    Groups of four two-week-old puppies were administered serial dilutions of an intranasal vaccine containing live Bordetella bronchiseptica and canine parainfluenza virus vaccine and housed individually in isolator cages. Three vaccinated groups and one unvaccinated control group were exposed to virulent B bronchiseptica four weeks after vaccination and evaluated. Nasal swabs for bacterial culture and sera for agglutination tests were taken from all the dogs every week for four weeks. The bacteria isolated were identified by growth on specific agar and by specific PCR to distinguish between vaccine and challenge strains. The vaccine strain persisted in the nasal cavity after vaccination but no adverse reactions were observed. Serum agglutination titres were raised in the vaccinated dogs at challenge. Vaccine strains were not isolated after the challenge from most of the vaccinated dogs. The challenge strain was shed in the dogs vaccinated with the lowest dose (10(6.0) cfu/dose) for two to three weeks but the other vaccinated groups (10(7.0) and 10(8.0) cfu/dose) shed the challenge strain transiently or not at all. Only the group vaccinated with 10(6.0) cfu/dose exhibited clinical signs after challenge.

  2. Continuous borehole strain and pore pressure in the near field of the 28 September 2004 M 6.0 parkfield, California, earthquake: Implications for nucleation, fault response, earthquake prediction and tremor

    USGS Publications Warehouse

    Johnston, M.J.S.; Borcherdt, R.D.; Linde, A.T.; Gladwin, M.T.

    2006-01-01

    Near-field observations of high-precision borehole strain and pore pressure, show no indication of coherent accelerating strain or pore pressure during the weeks to seconds before the 28 September 2004 M 6.0 Parkfield earthquake. Minor changes in strain rate did occur at a few sites during the last 24 hr before the earthquake but these changes are neither significant nor have the form expected for strain during slip coalescence initiating fault failure. Seconds before the event, strain is stable at the 10-11 level. Final prerupture nucleation slip in the hypocentral region is constrained to have a moment less than 2 ?? 1012 N m (M 2.2) and a source size less than 30 m. Ground displacement data indicate similar constraints. Localized rupture nucleation and runaway precludes useful prediction of damaging earthquakes. Coseismic dynamic strains of about 10 microstrain peak-to-peak were superimposed on volumetric strain offsets of about 0.5 microstrain to the northwest of the epicenter and about 0.2 microstrain to the southeast of the epicenter, consistent with right lateral slip. Observed strain and Global Positioning System (GPS) offsets can be simply fit with 20 cm of slip between 4 and 10 km on a 20-km segment of the fault north of Gold Hill (M0 = 7 ?? 1017 N m). Variable slip inversion models using GPS data and seismic data indicate similar moments. Observed postseismic strain is 60% to 300% of the coseismic strain, indicating incomplete release of accumulated strain. No measurable change in fault zone compliance preceding or following the earthquake is indicated by stable earth tidal response. No indications of strain change accompany nonvolcanic tremor events reported prior to and following the earthquake.

  3. Field and laboratory investigations of selenium transformation. Quarterly report

    SciTech Connect

    Atalay, A.; Koll, K.J.

    1990-12-01

    This quarterly report discusses the preparation and results of a field investigation of a selected coal mine site in Oklahoma. The field investigation has been on-going since July 1990. An analysis of this data would be useful in providing information for potential Se mobility from a coal mine site and the distribution of Se in a soil profile of reclaimed land. Also, included is the investigation and preliminary results of SeO{sub 3}{sup 2{minus}} adsorption and desorption using different soil media, including coal mine spoils (overburden).

  4. Identification of the Rdl mutation in laboratory and field strains of the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae).

    PubMed

    Bass, Chris; Schroeder, Iris; Turberg, Andreas; Field, Linda M; Williamson, Martin S

    2004-12-01

    In many insect species, resistance to cyclodiene insecticides is caused by amino acid substitutions at a single residue (A302) within the M2 transmembrane region of the gamma-aminobutyric acid (GABA) receptor sub-unit termed Rdl (resistance to dieldrin). These mutations (A302S and A302G) have also been shown to confer varying levels of cross-resistance to fipronil, a phenylpyrazole insecticide with a similar mode of action to cyclodienes. To investigate the possible occurrence of these mutations in the cat flea, Ctenocephalides felis (Bouché), a 176-bp fragment of the cat flea Rdl gene, encompassing the mutation site, was PCR amplified and sequenced from nine laboratory flea strains. The A302S mutation was found in eight of the nine strains analysed, although the relative frequency of the mutant allele varied between strains. Only one strain (R6) was found to be homozygous for the S302 allele in all the individuals tested, and this correlated with previous reports of low-level fipronil resistance in this strain. A PCR-based diagnostic assay, capable of screening individual fleas for this mutation, was developed and used to survey a range of fleas collected at random from veterinary clinics in the UK and USA. The A302S mutation was present at a high frequency in these domestic pet populations.

  5. Ultrathin strain-gated field effect transistor based on In-doped ZnO nanobelts

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Du, Junli; Li, Bing; Zhang, Shuhao; Hong, Mengyu; Zhang, Xiaomei; Liao, Qingliang; Zhang, Yue

    2017-08-01

    In this work, we fabricated a strain-gated piezoelectric transistor based on single In-doped ZnO nanobelt with ±(0001) top/bottom polar surfaces. In the vertical structured transistor, the Pt tip of the AFM and Au film are used as source and drain electrode. The electrical transport performance of the transistor is gated by compressive strains. The working mechanism is attributed to the Schottky barrier height changed under the coupling effect of piezoresistive and piezoelectric. Uniquely, the transistor turns off under the compressive stress of 806 nN. The strain-gated transistor is likely to have important applications in high resolution mapping device and MEMS devices.

  6. Graphene-based spin switch device via modulated Rashba field and strain

    NASA Astrophysics Data System (ADS)

    Diniz, G. S.; Vernek, E.; Souza, F. M.

    2017-01-01

    We investigate the spin-resolved transport in a two-terminal zigzag graphene nanoribbon device with two independent gate induced Rashba spin-orbit coupling regions and in the presence of strain. By employing a recursive Green's function technique to the tight-binding model for the graphene nanoribbon, we calculate the spin-resolved conductance of the system. We show that by switching the sign of one of the gates it is possible to select which spin component will be transmitted. Moreover, our results show that an uniaxial strain applied to the nanoribbon plays a significant role in the transport, providing and additional manner to control the spin-polarized conductance. This makes the present system a potential candidate for future implementations of spin-based mechanical strain sensors.

  7. Single Nucleotide Polymorphism Genotyping and Distribution of Coxiella burnetii Strains from Field Samples in Belgium

    PubMed Central

    Dal Pozzo, Fabiana; Renaville, Bénédicte; Martinelle, Ludovic; Renaville, Robert; Thys, Christine; Smeets, François; Kirschvink, Nathalie; Grégoire, Fabien; Delooz, Laurent; Czaplicki, Guy

    2015-01-01

    The genotypic characterization of Coxiella burnetii provides useful information about the strains circulating at the farm, region, or country level and may be used to identify the source of infection for animals and humans. The aim of the present study was to investigate the strains of C. burnetii circulating in caprine and bovine Belgian farms using a single nucleotide polymorphism (SNP) technique. Direct genotyping was applied to different samples (bulk tank milk, individual milk, vaginal swab, fetal product, and air sample). Besides the well-known SNP genotypes, unreported ones were found in bovine and caprine samples, increasing the variability of the strains found in the two species in Belgium. Moreover, multiple genotypes were detected contemporarily in caprine farms at different years of sampling and by using different samples. Interestingly, certain SNP genotypes were detected in both bovine and caprine samples, raising the question of interspecies transmission of the pathogen. PMID:26475104

  8. Microarray-based comparative genomic profiling of reference strains and selected Canadian field isolates of Actinobacillus pleuropneumoniae

    PubMed Central

    Gouré, Julien; Findlay, Wendy A; Deslandes, Vincent; Bouevitch, Anne; Foote, Simon J; MacInnes, Janet I; Coulton, James W; Nash, John HE; Jacques, Mario

    2009-01-01

    Background Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is a highly contagious respiratory pathogen that causes severe losses to the swine industry worldwide. Current commercially-available vaccines are of limited value because they do not induce cross-serovar immunity and do not prevent development of the carrier state. Microarray-based comparative genomic hybridizations (M-CGH) were used to estimate whole genomic diversity of representative Actinobacillus pleuropneumoniae strains. Our goal was to identify conserved genes, especially those predicted to encode outer membrane proteins and lipoproteins because of their potential for the development of more effective vaccines. Results Using hierarchical clustering, our M-CGH results showed that the majority of the genes in the genome of the serovar 5 A. pleuropneumoniae L20 strain were conserved in the reference strains of all 15 serovars and in representative field isolates. Fifty-eight conserved genes predicted to encode for outer membrane proteins or lipoproteins were identified. As well, there were several clusters of diverged or absent genes including those associated with capsule biosynthesis, toxin production as well as genes typically associated with mobile elements. Conclusion Although A. pleuropneumoniae strains are essentially clonal, M-CGH analysis of the reference strains of the fifteen serovars and representative field isolates revealed several classes of genes that were divergent or absent. Not surprisingly, these included genes associated with capsule biosynthesis as the capsule is associated with sero-specificity. Several of the conserved genes were identified as candidates for vaccine development, and we conclude that M-CGH is a valuable tool for reverse vaccinology. PMID:19239696

  9. Tensile strained Ge tunnel field-effect transistors: k · p material modeling and numerical device simulation

    SciTech Connect

    Kao, Kuo-Hsing; De Meyer, Kristin; Verhulst, Anne S.; Van de Put, Maarten; Soree, Bart; Magnus, Wim; Vandenberghe, William G.

    2014-01-28

    Group IV based tunnel field-effect transistors generally show lower on-current than III-V based devices because of the weaker phonon-assisted tunneling transitions in the group IV indirect bandgap materials. Direct tunneling in Ge, however, can be enhanced by strain engineering. In this work, we use a 30-band k · p method to calculate the band structure of biaxial tensile strained Ge and then extract the bandgaps and effective masses at Γ and L symmetry points in k-space, from which the parameters for the direct and indirect band-to-band tunneling (BTBT) models are determined. While transitions from the heavy and light hole valence bands to the conduction band edge at the L point are always bridged by phonon scattering, we highlight a new finding that only the light-hole-like valence band is strongly coupling to the conduction band at the Γ point even in the presence of strain based on the 30-band k · p analysis. By utilizing a Technology Computer Aided Design simulator equipped with the calculated band-to-band tunneling BTBT models, the electrical characteristics of tensile strained Ge point and line tunneling devices are self-consistently computed considering multiple dynamic nonlocal tunnel paths. The influence of field-induced quantum confinement on the tunneling onset is included. Our simulation predicts that an on-current up to 160 (260) μA/μm can be achieved along with on/off ratio > 10{sup 6} for V{sub DD} = 0.5 V by the n-type (p-type) line tunneling device made of 2.5% biaxial tensile strained Ge.

  10. Determination of elastic strain fields and geometrically necessary dislocation distributions near nanoindents using electron back scatter diffraction

    NASA Astrophysics Data System (ADS)

    Wilkinson, Angus J.; Randman, David

    2010-03-01

    The deformation around a 500-nm deep Berkovich indent in a large grained Fe sample has been studied using high resolution electron back scatter diffraction (EBSD). EBSD patterns were obtained in a two-dimensional map around the indent on the free surface. A cross-correlation-based analysis of small shifts in many sub-regions of the EBSD patterns was used to determine the variation of elastic strain and lattice rotations across the map at a sensitivity of ∼±10-4. Elastic strains were smaller than lattice rotations, with radial strains found to be compressive and hoop strains tensile as expected. Several analyses based on Nye's dislocation tensor were used to estimate the distribution of geometrically necessary dislocations (GNDs) around the indent. The results obtained using different assumed dislocation geometries, optimisation routines and different contributions from the measured lattice rotation and strain fields are compared. Our favoured approach is to seek a combination of GND types which support the six measurable (of a possible nine) gradients of the lattice rotations after correction for the 10 measurable elastic strain gradients, and minimise the total GND line energy using an L1 optimisation method. A lower bound estimate for the noise on the GND density determination is ∼±1012 m-2 for a 200-nm step size, and near the indent densities as high as 1015 m-2 were measured. For comparison, a Hough-based analysis of the EBSD patterns has a much higher noise level of ∼±1014m-2 for the GND density.

  11. Comparison of regional and local horizontal strain field on the area of Central Europe determined from GPS data

    NASA Astrophysics Data System (ADS)

    Kontny, B.

    2012-04-01

    Permanent GPS observations on EPN stations are being continued already about 15 years and so velocities of horizontal and vertical movements of the sites are determined with the great credibility. However density of the EPN sites on the area of Central Europe allow to determine only a very general model of deformation field. For determining the local strain field epoch-making GPS observations in local research networks can be used. As en example the GEOSUD GPS Network located in the area of the Sudeten mountains in South-West Poland were used. Velocities of GPS points were estimated from observations of annually repeated two-day measuring campaigns, connected to the EPN stations. On the basis of these velocities local velocity field and local strain field were estimated. The toolbox grid_strain (Teza, Pesci and Galgaro, 2008) was used. Areas of the maximum compressions and extensions were outlined as well as they were confronted with the tectonic structure of area. In the picture of the deformation field clearly four principal zones of deformations are standing out. The presence of the Sudetic Marginal Fault is becoming scratched slightly in south-eastern his parts. Values of deformations in the vicinity of fault zone are generally smaller than in more distant area. It is proving the hypothesis on interseismic character of changes and the weak tectonic activity of the fault. Such an image of horizontal deformations in which extensions are perpendicular to main direction of the fault line, is matching with the hypothesis on normal character of the SMF. On the entire research area however compression deformations are dominating.

  12. Cascaded fiber-optic Fabry-Perot interferometers with Vernier effect for highly sensitive measurement of axial strain and magnetic field.

    PubMed

    Zhang, Peng; Tang, Ming; Gao, Feng; Zhu, Benpeng; Fu, Songnian; Ouyang, Jun; Shum, Perry Ping; Liu, Deming

    2014-08-11

    We report a highly sensitive fiber-optic sensor based on two cascaded intrinsic fiber Fabry-Perot interferometers (IFFPIs). The cascaded IFFPIs have different free spectral ranges (FSRs) and are formed by a short section of hollow core photonic crystal fiber sandwiched by two single mode fibers. With the superposition of reflective spectrum with different FSRs, the Vernier effect will be generated in the proposed sensor and we found that the strain sensitivity of the proposed sensor can be improved from 1.6 pm/με for a single IFFPI sensor to 47.14 pm/με by employing the Vernier effect. The sensor embed with a metglas ribbon can be also used to measure the magnetic field according to the similar principle. The sensitivity of the magnetic field measurement is achieved to be 71.57 pm/Oe that is significantly larger than the 2.5 pm/Oe for a single IFFPI sensor.

  13. Human melatonin in magnetic fields: Second study. Final report

    SciTech Connect

    Graham, C.; Cook, M.R.; Cohen, H.D.

    1995-11-01

    Melatonin (MLT) is a hormone secreted primarily at night by the pineal gland in the brain. A number of studies suggest it is part of the body`s natural defenses against cancer. This hormone is reported to stimulate immune function and has been implicated in the control of cell proliferation, the growth of transplanted tumors, and the promotion and/or co-promotion of mammary tumors. MLT also plays a key role in the regulation of reproductive hormones implicated in a number of carcinogenic processes. Studies with rodents, although not always consistent, suggest that nocturnal MLT levels may be suppressed by electric or magnetic field (EMF) exposure. This relationship has been proposed as a possible biological mechanism to account for epidemiological reports linking chronic EMF exposure and increased cancer risk. Research was needed to determine if a similar suppression of MLT occurs when humans are exposed to magnetic fields at night.

  14. Microhardness, strength and strain field characterization of self-reacting friction stir and plug welds of dissimilar aluminum alloys

    NASA Astrophysics Data System (ADS)

    Horton, Karla Renee

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side and a SR-FSW (AA2014-T6 to AA2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures. The initial weld microstructure analysis showed a nugget region with fine grains and a displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the nugget region. The displaced material shared the same hardness as the parent material. Dynamic recrystallization was observed in the SR-FSW zone and the displaced weld seam region. The welds revealed a fine grain structure in the SR-FSW zone with a sharp demarcation seen on the advancing side and fairly diffuse flow observed on the retreating side. The parent material hardness is 145 HV700g with a drop in hardness starting at the HAZ to 130 HV700g. The hardness further drops in the TMAZ to118 HV700g with an increase representing a dispersed interface of AA2014-T6 material to 135 HV700g. The hardness then drops significantly within the nugget region to 85 HV700g followed by an increase through the retreating side TMAZ into the HAZ to 135 HV 700g. There was a sharp increase in the hardness value within

  15. Intragranular strain field in columnar ice during elasto-viscoplatic transient creep regime, and relation with the local microstructure

    NASA Astrophysics Data System (ADS)

    Grennerat, F.; Montagnat, M.; Duval, P.; Vacher, P.; Castelnau, O.

    2009-12-01

    The viscoplastic behaviour of polycrystalline ice is strongly affected by the very strong anisotropy of ice crystals. Indeed, in the dislocations creep regime relevant e.g. for ice sheet flow, dislocation glide on the basal plane of ice single crystals leads to strain-rates ˜6 order of magnitude larger than strain-rates that might be obtain if only non-basal glide is activated. At the polycrystal scale, this behaviour is responsible for a strong mechanical interaction between grains in the secondary (stationary) creep regime, and strain-rate is essentially partitioned between soft grains well-oriented for basal glide and hard grains exhibiting an unfavourable orientation for basal slip. As a consequence, the macroscopic flow stress at the polycrystal scale essentially depends on the resistance of the hardest slip systems or on the associated accommodation processes such as climb of basal dislocation on non-basal planes. One therefore expects very strong strain localization in polycrystalline ice in this viscoplastic regime. On the other hand, during transient effects, elasticity comes in plays. But since elasticity of ice single crystal is almost isotropic, very different strain localizations are expected in purely elastic and purely viscoplastic deformation regimes. Consequently, strain-rate decreases by several orders of magnitude during the transient creep of polycrystalline ice. This effect is associated to stress redistribution between hard and soft grains, and is probably of great importance e.g. to understand transient regimes such as tide effects on ice shelves or on icy planets. It can be described by the coupling between elastic and viscoplastic responses, and the associated long-term memory effect. In view of a better understanding of such effects, and development of adapted micromechanical models, we are engaged in the measurement of intragranular strain field and field heterogeneities is columnar ices deformed under loading involving stress increments

  16. Biosynthesis of compatible solutes in rhizobial strains isolated from Phaseolus vulgaris nodules in Tunisian fields

    PubMed Central

    2010-01-01

    Background Associated with appropriate crop and soil management, inoculation of legumes with microbial biofertilizers can improve food legume yield and soil fertility and reduce pollution by inorganic fertilizers. Rhizospheric bacteria are subjected to osmotic stress imposed by drought and/or NaCl, two abiotic constraints frequently found in semi-arid lands. Osmostress response in bacteria involves the accumulation of small organic compounds called compatible solutes. Whereas most studies on rhizobial osmoadaptation have focussed on the model species Sinorhizobium meliloti, little is known on the osmoadaptive mechanisms used by native rhizobia, which are good sources of inoculants. In this work, we investigated the synthesis and accumulations of compatible solutes by four rhizobial strains isolated from root nodules of Phaseolus vulgaris in Tunisia, as well as by the reference strain Rhizobium tropici CIAT 899T. Results The most NaCl-tolerant strain was A. tumefaciens 10c2, followed (in decreasing order) by R. tropici CIAT 899, R. leguminosarum bv. phaseoli 31c3, R. etli 12a3 and R. gallicum bv. phaseoli 8a3. 13C- and 1H-NMR analyses showed that all Rhizobium strains synthesized trehalose whereas A. tumefaciens 10c2 synthesized mannosucrose. Glutamate synthesis was also observed in R. tropici CIAT 899, R. leguminosarum bv. phaseoli 31c3 and A. tumefaciens 10c2. When added as a carbon source, mannitol was also accumulated by all strains. Accumulation of trehalose in R. tropici CIAT 899 and of mannosucrose in A. tumefaciens 10c2 was osmoregulated, suggesting their involvement in osmotolerance. The phylogenetic analysis of the otsA gene, encoding the trehalose-6-phosphate synthase, suggested the existence of lateral transfer events. In vivo 13C labeling experiments together with genomic analysis led us to propose the uptake and conversion pathways of different carbon sources into trehalose. Collaterally, the β-1,2-cyclic glucan from R. tropici CIAT 899 was co

  17. Study of Strain Induction for Metal-Oxide-Semiconductor Field-Effect Transistors using Transparent Dummy Gates and Stress Liners

    NASA Astrophysics Data System (ADS)

    Kosemura, Daisuke; Takei, Munehisa; Nagata, Kohki; Akamatsu, Hiroaki; Kohno, Masayuki; Nishita, Tatsuo; Nakanishi, Toshio; Ogura, Atsushi

    2009-06-01

    Strain induction was studied on a sample that had a dummy gate tetraethyl orthosilicate-silicon dioxide (TEOS-SiO2) and SiN film by UV-Raman spectroscopy with high spatial and high wave-number resolution. The UV laser penetrated through the dummy gate that was transparent to UV light, which enabled us to evaluate strain in the channel of the metal-oxide-semiconductor field-effect transistor (MOSFET) model. Furthermore, we compared stress profiles obtained by finite element (FE) calculations with those obtained by UV-Raman measurements. There was a difference between the stress profiles in the line-and-space pattern sample and in the dummy-gate sample; large compressive (tensile) strains were concentrated at the channel edges in the dummy-gate sample with the compressive (tensile) stress liner, although both tensile and compressive strains existed at the channel edge in the line-and-space pattern sample. The results from UV-Raman spectroscopy were consistent with those obtained by the FE calculation.

  18. Laboratory and field evaluation of an entomopathogenic fungus, Isaria cateniannulata strain 08XS‐1, against Tetranychus urticae (Koch)

    PubMed Central

    Zhang, Xiaona; Zou, Xiao; Guo, Jianjun

    2016-01-01

    Abstract BACKGROUND The two‐spotted mite, Tetranychus urticae Koch, is one of the most serious mite pests of crops throughout the world. Biocontrol of the mite with fungal agents has long been paid much attention because of the development of insecticide resistance and the severe restriction of chemical pesticides. In this study, the efficacy of submerged conidia of the entomopathogenic fungus Isaria cateniannulata strain 08XS‐1 against T. urticae eggs, larvae and female adults was evaluated at different temperatures and humidity in the laboratory and under field conditions. RESULTS The results showed that a suspension of 2 × 107 submerged conidia mL −1 caused the highest mortalities of mite eggs, larvae and females (100, 100 and 70% respectively) at 100% relative humidity and 25 °C in the laboratory. In the field experiments against the mites, a suspension of 2 × 108 submerged conidia mL −1 achieved significant efficiency – the relative control effects were 88.6, 83.8 and 83%, respectively, in cucumber, eggplant and bean fields after 10 days of treatment. CONCLUSION The results suggest that the I. cateniannulata strain 08XS‐1 is a potential fungal agent, with acceptable production cost of conidia, against T. urticae in the field in an area such as southwestern China with higher air humidity. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:26775712

  19. Misfit strain-temperature phase diagrams and domain stability of asymmetric ferroelectric capacitors: Thermodynamic calculation and phase-field simulation

    SciTech Connect

    Chen, W. J.; Zheng, Yue Wu, C. M.; Wang, B. Ma, D. C.

    2014-03-07

    Thermodynamic calculation and phase-field simulation have been conducted to investigate the misfit strain-temperature phase diagrams, dielectric property, and domain stability of asymmetric ferroelectric capacitors (FCs), with considering the effects of dissimilar screening properties and work function steps at the two interfaces. The distinct features of asymmetric FCs from their symmetric counterparts have been revealed and discussed. Polar states with nonzero out-of-plane polarization in parallel with the built-in field are found preferential to form in asymmetric FCs. Meanwhile, the built-in field breaks the degeneracy of states with out-of-plane polarization in anti-directions. This leads to the necessity of redefining phases according to the bistability of out-of-plane polarization. Moreover, the phase stability as well as the dielectric behavior can be significantly controlled by the properties of electrodes, misfit strain, and temperature. The phase-field simulation result also shows that polydomain instability would happen in asymmetric FCs as the equivalence of domain stability in anti-directions is destroyed.

  20. Crustal strain fields in the surrounding areas of the Ordos Block, central China, estimated by the least-squares collocation technique

    NASA Astrophysics Data System (ADS)

    Qu, Wei; Lu, Zhong; Zhang, Ming; Zhang, Qin; Wang, Qingliang; Zhu, Wu; Qu, Feifei

    2017-05-01

    The Ordos Block and its surrounding areas play a special role in the kinetic pattern of current tectonic deformation in mainland China (East Asia). In order to better understand the recent crustal deformation and geodynamics of this region, we use GPS velocities and employ the least-squares collocation (LSC) technique to estimate the distribution of the crustal strain rate fields. We calculate the principal components of strains, such as the maximum shear strains, the plane strain gradients and the principal axes of strains. The strain fields obtained in this paper can well portray crustal deformation in the region. Our results show that the relatively higher maximum shearing strain rates are mainly distributed over region surrounding the Ordos Block, indicating these periphery areas have intense crustal activities. Indeed, these periphery areas encompass major active tectonic belts (e.g., the western edge of the Qilian Fold System, the northeastern margin of the Tibetan Plateau and the Taihang Mountain) and active grabens (e.g., Yinchuan, Hetao, Shanxi and Weihe Grabens). Significant plane strain gradients concentrated over the periphery areas of the Ordos Block, indicating that these areas have more intense crustal activity and are more prone to earthquakes. The principle strain rates also show the strain rates for the periphery of the Ordos Block are higher than other regions. The highest strain rates are along the southwestern side of the Ordos Block, indicating that the eastward extrusion dynamics from the Tibetan Plateau may still be the main cause of tectonic deformation in this region. The extensional strains are present in most parts of the Yinchuan, Hetao and Shanxi Grabens. Finally, the characteristics of the strain fields predicted by the LSC technique are discussed, and some interesting tectonic deformation information can be found through further comparison with the strain results predicted by other methods The detailed results and findings obtained

  1. X-ray microbeam three-dimensional topography for dislocation strain-field analysis of 4H-SiC

    NASA Astrophysics Data System (ADS)

    Tanuma, R.; Mori, D.; Kamata, I.; Tsuchida, H.

    2013-07-01

    This paper describes the strain-field analysis of threading edge dislocations (TEDs) and basal-plane dislocations (BPDs) in 4H-SiC using x-ray microbeam three-dimensional (3D) topography. This 3D topography enables quantitative strain-field analysis, which measures images of effective misorientations (Δω maps) around the dislocations. A deformation-matrix-based simulation algorithm is developed to theoretically evaluate the Δω mapping. Systematic linear calculations can provide simulated Δω maps (Δωsim maps) of dislocations with different Burgers vectors, directions, and reflection vectors for the desired cross-sections. For TEDs and BPDs, Δω maps are compared with Δωsim maps, and their excellent correlation is demonstrated. Two types of asymmetric reflections, high- and low-angle incidence types, are compared. Strain analyses are also conducted to investigate BPD-TED conversion near an epilayer/substrate interface in 4H-SiC.

  2. Faulting of rocks in three-dimensional strain fields I. Failure of rocks in polyaxial, servo-control experiments

    USGS Publications Warehouse

    Reches, Z.; Dieterich, J.H.

    1983-01-01

    The dependence of the number of sets of faults and their orientation on the intermediate strain axis is investigated through polyaxial tests, reported here, and theoretical analysis, reported in an accompanying paper. In the experiments, cubic samples of Berea sandstone, Sierra-White and Westerly granites, and Candoro and Solnhofen limestones were loaded on their three pairs of faces by three independent, mutually perpendicular presses at room temperature. Two of the presses were servo-controlled and applied constant displacement rates throughout the experiment. Most samples display three or four sets of faults in orthorhombic symmetry. These faults form in several yielding events that follow a stage of elastic deformation. In many experiments, the maximum and the intermediate compressive stresses interchange orientations during the yielding events, where the corresponding strains are constant. The final stage of most experiments is characterized by slip along the faults. ?? 1983.

  3. Essential oils as potential adulticides against two populations of Aedes aegypti, the laboratory and natural field strains, in Chiang Mai province, northern Thailand.

    PubMed

    Chaiyasit, Dana; Choochote, Wej; Rattanachanpichai, Eumporn; Chaithong, Udom; Chaiwong, Prasong; Jitpakdi, Atchariya; Tippawangkosol, Pongsri; Riyong, Doungrat; Pitasawat, Benjawan

    2006-11-01

    Essential oils derived from five plant species, celery (Apium graveolens), caraway (Carum carvi), zedoary (Curcuma zedoaria), long pepper (Piper longum), and Chinese star anise (Illicium verum), were subjected to investigation of adulticidal activity against mosquito vectors. Two populations of Aedes aegypti, the laboratory and natural field strains, collected in Chiang Mai province, northern Thailand were tested in pyrethroid-susceptibility bioassays. The results revealed that the natural field strain of A. aegypti was resistant to permethrin, with mortality rates ranging from 51 to 66%. A mild susceptibility, with mortality rates ranging from 82 to 88%, was observed in the natural field strain of A. aegypti exposed to lambdacyhalothrin, which suggested that this strain was tolerant and might be resistant to this insecticide. However, laboratory-reared A. aegypti exposed to discriminating dosages of permethrin and lambdacyhalothrin induced 100% mortality in all cases, thus indicating complete susceptibility of this strain to these insecticides. The adulticidal activity determined by topical application revealed that all five essential oils exerted a promising adulticidal efficacy against both laboratory and natural field strains of A. aegypti. Although the laboratory strain was slightly more susceptible to these essential oils than the natural field strain, no statistically significant difference was observed. Moreover, comparison of the adulticidal activity indicated that the performance of these essential oils against the two strains of A. aegypti was similar. The highest potential was established from caraway, followed by zedoary, celery, long pepper, and Chinese star anise, with an LC(50) in the laboratory strain of 5.44, 5.94, 5.96, 6.21, and 8.52 microg/mg female, respectively, and 5.54, 6.02, 6.14, 6.35, and 8.83 microg/mg female, respectively, in the field strain. These promising essential oils are, therefore, an alternative in developing and producing

  4. Gene transcription and electromagnetic fields. Final progress report

    SciTech Connect

    Henderson, A.S.

    1992-12-31

    Our overall aim is to obtain sufficient information to allow us to ultimately determine whether ELF EM field exposure is an initiating factor in neoplastic transformation and/or if exposure can mimic characteristics of the second-step counterpart in neoplastic disease. This aim is based on our previous findings that levels of some transcripts are increased in cells exposed to EM fields. While the research is basic in nature, the ramifications have bearing on the general safety of exposure to EM fields in industrial and everyday life. A large array of diverse biological effects are reported to occur as the result of exposure to elf EM fields, suggesting that the cell response to EM fields is at a basic level, presumably initiated by molecular and/or biophysical events at the cell membrane. The hypothesized route is a signal transduction pathway involving membrane calcium fluxes. Information flow resulting from signal transduction can mediate the induction of regulatory factors in the cell, and directly affect how transcription is regulated.

  5. Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing

    PubMed Central

    Fardisi, Mahsa; Gondhalekar, Ameya D.

    2017-01-01

    Abstract Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations. PMID:28334270

  6. Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing.

    PubMed

    Fardisi, Mahsa; Gondhalekar, Ameya D; Scharf, Michael E

    2017-03-20

    Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations.

  7. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression.

    PubMed

    Keir, Derek; Belachew, M; Ebinger, C J; Kendall, J-M; Hammond, J O S; Stuart, G W; Ayele, A; Rowland, J V

    2011-01-01

    Rifting of the continents leading to plate rupture occurs by a combination of mechanical deformation and magma intrusion, yet the spatial and temporal scales over which these alternate mechanisms localize extensional strain remain controversial. Here we quantify anisotropy of the upper crust across the volcanically active Afar Triple Junction using shear-wave splitting from local earthquakes to evaluate the distribution and orientation of strain in a region of continental breakup. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The lack of rift-perpendicular anisotropy in the lithosphere, and corroborating geoscientific evidence of extension dominated by dyking, provide strong evidence that magma intrusion achieves the majority of plate opening in this zone of incipient plate rupture.

  8. Typing of field rabies virus strains in FR Yugoslavia by limited sequence analysis and monoclonal antibodies.

    PubMed

    Stankov, S

    2001-01-01

    A total of 32 rabies virus isolates (15 of fox, 14 of cat and 3 of dog origin) from the territory of FR Yugoslavia were collected from December 1996 till February 1998 and analyzed by limited sequencing of N gene and by indirect immunofluorescence and a panel of 20 antinucleocapsid monoclonal antibodies (MAbs). All examined strains were characterized as sylvatic fox strains. Two main genetic variants were detected, 15 isolates belonging to Group I, 14 belonging to Group II, while the remaining 3 could not be classified into any group. This classification was confirmed by MAbs. The obtained results indicate at least two independent cycles of rabies transmission, probably resulting from multiple modes of transmission to the territories now belonging to FR Yugoslavia.

  9. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression

    PubMed Central

    Keir, Derek; Belachew, M.; Ebinger, C.J.; Kendall, J.-M.; Hammond, J.O.S.; Stuart, G.W.; Ayele, A.; Rowland, J.V.

    2011-01-01

    Rifting of the continents leading to plate rupture occurs by a combination of mechanical deformation and magma intrusion, yet the spatial and temporal scales over which these alternate mechanisms localize extensional strain remain controversial. Here we quantify anisotropy of the upper crust across the volcanically active Afar Triple Junction using shear-wave splitting from local earthquakes to evaluate the distribution and orientation of strain in a region of continental breakup. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The lack of rift-perpendicular anisotropy in the lithosphere, and corroborating geoscientific evidence of extension dominated by dyking, provide strong evidence that magma intrusion achieves the majority of plate opening in this zone of incipient plate rupture. PMID:21505441

  10. Exposure to Static Magnetic Field Stimulates Quorum Sensing Circuit in Luminescent Vibrio Strains of the Harveyi Clade

    PubMed Central

    Talà, Adelfia; Delle Side, Domenico; Buccolieri, Giovanni; Tredici, Salvatore Maurizio; Velardi, Luciano; Paladini, Fabio; De Stefano, Mario; Nassisi, Vincenzo; Alifano, Pietro

    2014-01-01

    In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule. PMID:24960170

  11. Bsn-t alleles from french field strains of agaricus bisporus

    PubMed

    Callac; Hocquart; Imbernon; Desmerger; Olivier

    1998-06-01

    In the Agaricus bisporus desert population in California, the dominant Bsn-t allele determines the production of tetrasporic basidia and homokaryotic spores (n) that characterize a heterothallic life cycle. Strains belonging to a French population have the Bsn-b/b genotype that results in bisporic basidia that produce heterokaryotic spores (n + n) which characterize a pseudohomothallic life cycle. More recombination occurs in the tetrasporic population than in the bisporic population. In France, tetrasporic strains are rare. For two such isolates, Bs 261 and Bs 423, we determined the life cycle, the heritability of the tetrasporic trait, the amount of variation in the recombination rate, and the haploid fruiting ability. We found that (i) Bs 261 was heterothallic, (ii) Bs 423 was homokaryotic and homothallic, (iii) Bs 261 was Bsn-t/b, (iv) recombination on a segment of chromosome I depended on the genotype at BSN, (v) some of the homokaryotic offspring of Bs 261 and all of the progeny of Bs 423 were able to fruit, (vi) Bs 261 and Bs 423 were closely related, and (vii) Bs 423 was partially intersterile with other strains of the species.

  12. Band structure engineering via piezoelectric fields in strained anisotropic CdSe/CdS nanocrystals

    PubMed Central

    Christodoulou, Sotirios; Rajadell, Fernando; Casu, Alberto; Vaccaro, Gianfranco; Grim, Joel Q.; Genovese, Alessandro; Manna, Liberato; Climente, Juan I.; Meinardi, Francesco; Rainò, Gabriele; Stöferle, Thilo; Mahrt, Rainer F.; Planelles, Josep; Brovelli, Sergio; Moreels, Iwan

    2015-01-01

    Strain in colloidal heteronanocrystals with non-centrosymmetric lattices presents a unique opportunity for controlling optoelectronic properties and adds a new degree of freedom to existing wavefunction engineering and doping paradigms. We synthesized wurtzite CdSe nanorods embedded in a thick CdS shell, hereby exploiting the large lattice mismatch between the two domains to generate a compressive strain of the CdSe core and a strong piezoelectric potential along its c-axis. Efficient charge separation results in an indirect ground-state transition with a lifetime of several microseconds, almost one order of magnitude longer than any other CdSe/CdS nanocrystal. Higher excited states recombine radiatively in the nanosecond time range, due to increasingly overlapping excited-state orbitals. k̇p calculations confirm the importance of the anisotropic shape and crystal structure in the buildup of the piezoelectric potential. Strain engineering thus presents an efficient approach to highly tunable single- and multiexciton interactions, driven by a dedicated core/shell nanocrystal design. PMID:26219691

  13. Effects of particle morphology and spacing on the strain fields in a plastically deforming matrix

    SciTech Connect

    Watt, D.F.; Xu, X.Q.; Lloyd, D.J.

    1996-02-01

    More than 25 models have been created using the ABAQUS three-dimensional non-linear finite element software to reveal the stress and strain distributions around and within particles in a plastically deforming matrix. The effects of particle shape, volume fraction and distribution have been examined. The major effect is that a fiber-like stress distribution is developed in the matrix, linking the particles in the direction of loading, regardless of the variations in geometry or properties. However the stress and strain distributions are altered in detail in a systematic fashion by all these variables. Stress in cubic particles are much higher than those in spherical particles. Hard particles which are closely spaced in the direction of loading develop very large stresses in the region between them on the line of loading, whereas the stresses are not nearly as significantly increased for particles closely spaced in the transverse direction. The variations in the distributions of stress and strain can be explained in a general way by reference to compatibility and equilibrium arguments.

  14. Measurement and modeling of strain fields in zirconium hydrides precipitated at a stress concentration

    SciTech Connect

    Allen, Gregory B.; Kerr, Matthew; Daymond, Mark R.

    2012-10-23

    Hydrogen adsorption into zirconium, as a result of corrosion in aqueous environments, leads to the precipitation of a secondary brittle hydride phase. These hydrides tend to first form at stress concentrations such as fretting flaws or cracks in engineering components, potentially degrading the structural integrity of the component. One mechanism for component failure is a slow crack growth mechanism known as Delayed Hydride Cracking (DHC), where hydride fracture occurs followed by crack arrest in the ductile zirconium matrix. The current work employs both an experimental and a modeling approach to better characterize the effects and behavior of hydride precipitation at such stress concentrations. Strains around stress concentrations containing hydrides were mapped using High Energy X-ray Diffraction (HEXRD). These studies highlighted important differences in the behavior of the hydride phase and the surrounding zirconium matrix, as well as the strain associated with the precipitation of the hydride. A finite element model was also developed and compared to the X-ray strain mapping results. This model provided greater insight into details that could not be obtained directly from the experimental approaches, as well as providing a framework for future modeling to predict the effects of hydride precipitation under varied conditions.

  15. Bsn-t Alleles from French Field Strains of Agaricus bisporus

    PubMed Central

    Callac, Philippe; Hocquart, Sophie; Imbernon, Micheline; Desmerger, Christophe; Olivier, Jean-Marc

    1998-01-01

    In the Agaricus bisporus desert population in California, the dominant Bsn-t allele determines the production of tetrasporic basidia and homokaryotic spores (n) that characterize a heterothallic life cycle. Strains belonging to a French population have the Bsn-b/b genotype that results in bisporic basidia that produce heterokaryotic spores (n + n) which characterize a pseudohomothallic life cycle. More recombination occurs in the tetrasporic population than in the bisporic population. In France, tetrasporic strains are rare. For two such isolates, Bs 261 and Bs 423, we determined the life cycle, the heritability of the tetrasporic trait, the amount of variation in the recombination rate, and the haploid fruiting ability. We found that (i) Bs 261 was heterothallic, (ii) Bs 423 was homokaryotic and homothallic, (iii) Bs 261 was Bsn-t/b, (iv) recombination on a segment of chromosome I depended on the genotype at BSN, (v) some of the homokaryotic offspring of Bs 261 and all of the progeny of Bs 423 were able to fruit, (vi) Bs 261 and Bs 423 were closely related, and (vii) Bs 423 was partially intersterile with other strains of the species. PMID:9603821

  16. Trip report for field visit to Fayetteville Shale gas wells.

    SciTech Connect

    Veil, J. A.; Environmental Science Division

    2007-09-30

    This report describes a visit to several gas well sites in the Fayetteville Shale on August 9, 2007. I met with George Sheffer, Desoto Field Manager for SEECO, Inc. (a large gas producer in Arkansas). We talked in his Conway, Arkansas, office for an hour and a half about the processes and technologies that SEECO uses. We then drove into the field to some of SEECO's properties to see first-hand what the well sites looked like. In 2006, the U.S. Department of Energy's (DOE's) National Energy Technology Laboratory (NETL) made several funding awards under a program called Low Impact Natural Gas and Oil (LINGO). One of the projects that received an award is 'Probabilistic Risk-Based Decision Support for Oil and Gas Exploration and Production Facilities in Sensitive Ecosystems'. The University of Arkansas at Fayetteville has the lead on the project, and Argonne National Laboratory is a partner. The goal of the project is to develop a Web-based decision support tool that will be used by mid- and small-sized oil and gas companies as well as environmental regulators and other stakeholders to proactively minimize adverse ecosystem impacts associated with the recovery of gas reserves in sensitive areas. The project focuses on a large new natural gas field called the Fayetteville Shale. Part of the project involves learning how the natural gas operators do business in the area and the technologies they employ. The field trip on August 9 provided an opportunity to do that.

  17. Field testing of high-efficiency supermarket refrigeration. Final report

    SciTech Connect

    Walker, D.

    1992-12-01

    The Electric Power Research Institute (EPRI) has undertaken a field test to quantify the performance of high-efficiency supermarket refrigeration. The initial work on this project was presented in EPRI report CU-6268 ``Supermarket Refrigeration Modeling and Field Demonstration.`` The information given here was generated through continued testing at the field test site. The field test was conducted at a supermarket owned by Safeway Stores, Inc., that was located in Menlo Park, CA. Testing was performed with the existing conventional refrigeration system and a high-efficiency multiplex refrigeration system that was installed for these tests. The results of the testing showed that the high-efficiency multiplex system reduced refrigeration energy consumption by 23.9% and peak electric demand for refrigeration by 30.0%. Analyses of these savings showed that the largest portion was due to the use of high-efficiency compressors (29.5% of total saving). Floating head pressure control, ambient and mechanical subcooling, compressor multiplexing and hot gas defrost accounted for 50% of total savings. The remainder of the savings (20.5%) were attributed to the use of an evaporative condenser. Tests were also conducted with several retrofit technologies. The most promising results were obtained with external liquid-suction heat exchangers installed at the outlets of the display cases. Favorable paybacks were calculated for these exchangers when they were used with very low and low temperature refrigeration.

  18. Supermarket refrigeration modeling and field demonstration: Interim report

    SciTech Connect

    Walker, D.H.; Deming, G.I.

    1989-03-01

    The Electric Power Research Institute (EPRI) has undertaken a project to investigate supermarket refrigeration. The objectives of this project are (1) to develop an energy use and demand model of supermarket refrigeration systems and (2) to carry out an extensive field test of such systems in an operating supermarket. To accomplish these goals, a supermarket owned by Safeway Stores, Inc., and located in Menlo Park, CA, with an existing conventional refrigeration system utilizing single compressor units, was equipped with a state-of-the-art system with multiplexed parallel compressors. The store and both refrigeration systems were thoroughly instrumented and a test schedule was prepared and executed. Presented in this report are the preliminary results of this field test along with the initial validation of the energy use and demand model. 62 figs., 47 tabs.

  19. PISCES field chemical emissions monitoring project: Site 21 emissions report

    SciTech Connect

    1995-12-01

    This report is one of a series sponsored by the Electric Power Research Institute in the area of trace substance emissions from fossil-fuel power plants. This report presents the results of a sampling and analytical study to characterize trace substances emissions at Site 21. Site 21 is a pilot-scale electrostatic precipitator and wet flue gas desulfurization (FGD) system. The flue gas for the pilot unit is provided by an adjacent power plant boiler which bums a medium-sulfur bituminous, coal. The primary objective in the Site 21 sampling and analytical program was to quantify the various components of variance in the measurement of trace chemical species. In addition to the replicate sample trains typically conducted at previous PISCES field measurements, duplicate analyses and duplicate (simultaneous) sample trains were also conducted. This enabled the variance due to sampling, analytical, and process conditions to be estimated. The objective of this report is to transmit the detailed data to the U.S. Environmental Protection Agency (EPA) to assist the Agency in evaluating utility trace chemical emissions as well as the associated health risk impacts - as mandated in Title III of the 1990 Clean Air Act Amendments. This report does not attempt to compare the results with other sites. An assessment of data from all plants that have been tested is presented in the Electric Utility Trace Substances Synthesis Report.

  20. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    SciTech Connect

    Mark, J. Abraham Hudson Peter, A. John

    2014-04-24

    Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  1. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    NASA Astrophysics Data System (ADS)

    Mark, J. Abraham Hudson; Peter, A. John

    2014-04-01

    Third order susceptibility of third order harmonic generation is investigated in a Zn0.1Mg0.9Se/Zn0.8Mg0.2Se/Zn0.1Mg0.9Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  2. Field trip report: Observations made at Yucca Mountain, Nye County, Nevada. Special report No. 2

    SciTech Connect

    Hill, C.A.

    1993-03-01

    A field trip was made to the Yucca Mountain area on December 5-9, 1992 by Jerry Frazier, Don Livingston, Christine Schluter, Russell Harmon, and Carol Hill. Forty-three separate stops were made and 275 lbs. of rocks were collected during the five days of the field trip. Key localities visited were the Bare Mountains, Yucca Mountain, Calico Hills, Busted Butte, Harper Valley, Red Cliff Gulch, Wahmonie Hills, Crater Flat, and Lathrop Wells Cone. This report only describes field observations made by Carol Hill. Drawings are used rather than photographs because cameras were not permitted on the Nevada Test Site during this trip.

  3. Myxomatosis: the virulence of field strains of myxoma virus in a population of wild rabbits (Oryctolagus cuniculus L.) with high resistance to myxomatosis.

    PubMed Central

    Edmonds, J. W.; Nolan, I. F.; Shepherd, R. C.; Gocs, A.

    1975-01-01

    The virulence of field strains of myxoma virus is increasing in the Mallee region of Victoria where the resistance of the rabbit to myxomatosis is high. This suggests that the climax association will be a moderately severe disease. PMID:1056963

  4. Myxomatosis: the virulence of field strains of myxoma virus in a population of wild rabbits (Oryctolagus cuniculus L.) with high resistance to myxomatosis.

    PubMed

    Edmonds, J W; Nolan, I F; Shepherd, R C; Gocs, A

    1975-06-01

    The virulence of field strains of myxoma virus is increasing in the Mallee region of Victoria where the resistance of the rabbit to myxomatosis is high. This suggests that the climax association will be a moderately severe disease.

  5. EX SAIF SEREEA II--the field hospital clinical report.

    PubMed

    Bricknell, M C M; Wright, L A

    2004-12-01

    This paper places on record the clinical activity of the hospital facilities run by 22 Field Hospital on Exercise SAIF SEREEA II in Oman from August to November 2001. There were 1322 episodes of illness resulting in a hospital admission. The mean rate of admission was 1.96 patients per thousand per day (SD 13.62). The main causes of admission were gastrointestinal illness, conditions related to the heat and injuries. The reporting of health service utilisation data is an important duty of medical personnel during overseas deployments in order to add to the dataset available for the estimation of medical workload for future operations.

  6. Field transportable beta spectrometer. Innovative technology summary report

    SciTech Connect

    1998-12-01

    The objective of the Large-Scale Demonstration Project (LSDP) is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) Chicago Pile-5 Test Reactor (CP-5). The purpose of the LSDP is to demonstrate that by using innovative and improved deactivation and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies. One such capability being addressed by the D and D Focus Area is rapid characterization for facility contaminants. The technology was field demonstrated during the period January 7 through January 9, 1997, and offers several potential benefits, including faster turn-around time, cost reduction, and reduction in secondary waste. This report describes a PC controlled, field-transportable beta counter-spectrometer which uses solid scintillation coincident counting and low-noise photomultiplier tubes to count element-selective filters and other solid media. The dry scintillation counter used in combination with an element-selective technology eliminates the mess and disposal costs of liquid scintillation cocktails. Software in the instrument provides real-time spectral analysis. The instrument can detect and measure Tc-99, Sr-90, and other beta emitters reaching detection limits in the 20 pCi range (with shielding). Full analysis can be achieved in 30 minutes. The potential advantages of a field-portable beta counter-spectrometer include the savings gained from field generated results. The basis for decision-making is provided with a rapid turnaround analysis in the field. This technology would be competitive with the radiometric analysis done in fixed laboratories and the associated chain of custody operations.

  7. Strain Field in Ultrasmall Gold Nanoparticles Supported on Cerium-Based Mixed Oxides. Key Influence of the Support Redox State.

    PubMed

    López-Haro, Miguel; Yoshida, Kenta; Del Río, Eloy; Pérez-Omil, José A; Boyes, Edward D; Trasobares, Susana; Zuo, Jian-Min; Gai, Pratibha L; Calvino, José J

    2016-05-03

    Using a method that combines experimental and simulated Aberration-Corrected High Resolution Electron Microscopy images with digital image processing and structure modeling, strain distribution maps within gold nanoparticles relevant to real powder type catalysts, i.e., smaller than 3 nm, and supported on a ceria-based mixed oxide have been determined. The influence of the reduction state of the support and particle size has been examined. In this respect, it has been proven that reduction even at low temperatures induces a much larger compressive strain on the first {111} planes at the interface. This increase in compression fully explains, in accordance with previous DFT calculations, the loss of CO adsorption capacity of the interface area previously reported for Au supported on ceria-based oxides.

  8. Pathogenic characteristics of Marek's disease virus field strains prevalent in China and the effectiveness of existing vaccines against them.

    PubMed

    Zhang, Yan-ping; Li, Zhi-jie; Bao, Ke-yan; Lv, Hong-chao; Gao, Yu-long; Gao, Hong-lei; Qi, Xiao-le; Cui, Hong-yu; Wang, Yong-qiang; Ren, Xian-gang; Wang, Xiao-mei; Liu, Chang-jun

    2015-05-15

    The virulence of Marek's disease virus (MDV) is continuously evolving, and more virulent MDV pathotypes are emerging, thereby reducing the effectiveness of the existing vaccines. In this study, feather pulps were collected from diseased chickens in commercial chicken flocks in China that presented significant MD visceral tumors in 2011 and were inoculated into a monolayer of duck embryo fibroblasts (DEFs). Three field isolates of MDV were obtained by plaque cloning and identified as MDV via PCR and designated strains LCC, LLY, and LTS. Unvaccinated and CVI988 vaccine-vaccinated specific pathogen-free chickens were challenged at 7 days post vaccination (dpv) with 1000 plaque forming units of each of the respective MDV isolates. These strains induced gross MD lesions in all (100%) of the unvaccinated chickens, and the mortality rates of the unvaccinated chickens were 42.9%, 46.7%, and 23.1% by 60 days post challenge (dpc), respectively. The CVI988 vaccine induced protective indices (PIs) of 85.7, 92.3, and 66.7, respectively. These results showed that the pathogenic characteristics of the Chinese isolates were diverse and that vaccine CVI988 provided different levels of protection against them. These data indicated that the existence of variant MDV strains was a possible reason of immunity failure in China. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Transfer of the virulence-associated protein a-bearing plasmid between field strains of virulent and avirulent Rhodococcus equi.

    PubMed

    Stoughton, W; Poole, T; Kuskie, K; Liu, M; Bishop, K; Morrissey, A; Takai, S; Cohen, N

    2013-01-01

    Virulent and avirulent isolates of Rhodococcus equi coexist in equine feces and the environment and are a source of infection for foals. The extent to which plasmid transfer occurs among field strains is ill-defined and this information is important for understanding the epidemiology of R. equi infections of foals. To estimate the frequency of transfer of the virulence plasmid between virulent and avirulent strains of R. equi derived from foals and their environment. None. In vitro study; 5 rifampin-susceptible, virulent R. equi isolates obtained from clinically affected foals or air samples from a farm with a history of recurrent R. equi foal pneumonia were each mixed with 5 rifampin-resistant, avirulent isolates derived from soil samples, using solid medium, at a ratio of 10 donor cells (virulent) per recipient cell. Presumed transconjugates were detected by plating on media with rifampin and colony immunoblotting to detect the presence of the virulence-associated protein A. Three presumed transconjugates were detected among 2,037 recipient colonies, indicating an overall estimated transfer frequency of 0.15% (95% CI, 0.03–0.43%). All 3 transconjugates were associated with a single donor and 2 recipient strains. Genotyping and multiplex PCR of presumed transconjugates demonstrated transfer of the virulence-associated protein A-bearing plasmid between virulent and avirulent R. equi. Transfer of the virulence plasmid occurs with relatively high frequency. These findings could impact strategies to control or prevent R. equi through environmental management.

  10. Earth strain measurements with the transportable laser ranging system: Field techniques and planning

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.; Dorman, H. J.; Cahill, T.

    1982-01-01

    The potential of the transportable laser ranging system for monitoring the ground deformation around satellite ranging stations and other geodetic control points was examined with emphasis on testing the usefulness of the relative alteration technique. The temporal variation of the ratio of the length of each survey line to the mean length of all survey lines in a given area is directly related to the mean shear strain rate for the area. The data from a series of experimental measurements taken over the Los Angeles basin from a TLRS station at Mt. Wilson show that such ratios can be determined to an accuracy of one part in 10 million with a measurement program lasting for three days and without using any corrections for variations in atmospheric conditions. A numerical experiment using a set of hypothetical data indicates that reasonable estimates of the present shear strain rate and the direction of the principal axes in southern California can be deduced from such measurements over an interval of one to two years.

  11. Molecular evolution of American field strains of bluetongue and epizootic haemorrhagic disease viruses.

    PubMed

    Wilson, William C; Gaudreault, Natasha N; Jasperson, Dane C; Johnson, Donna J; Ostlund, Eileen N; Chase, Christopher L; Ruder, Mark G; Stallknecht, David E

    2015-01-01

    Recent Orbivirus occurrences in the Americas have been investigated using whole genome amplification and sequencing followed by phylogenetic analysis. The bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) whole genomes were amplified without prior sequence knowledge and deep sequenced. This technology was applied to evaluate BTV‑3 isolates spanning 4 decades from Florida, Arkansas, Mississippi, South Dakota, Central America, and the Caribbean basin. The results of the dataset analysis are consistent with the hypothesis that these viruses were introduced into the United States from Central America and the Caribbean basin. A similar analysis has been performed on a recent BTV‑2 isolate from California. It indicates that the BTV‑2 strain was likely introduced into Florida and then moved South to the Caribbean and West to California. A historical (1955‑2012) molecular characterisation of EHDV strains was also completed, and subsequently used as reference sequence for comparison of genomes from recent 2012 cattle isolates associated with clinical disease. Finally, this analysis was performed on BTV‑11 isolated from 2 canine cases and demonstrated that the genome sequences of the virus isolates from these cases were almost identical. These studies indicate the value of this technology in understanding virus epidemiology and ecology.

  12. [Bioremediation of oil-contaminated field by two Pseudomonas aeruginosa strains].

    PubMed

    Huang, Lei; Zhao, Tingting; He, Yun; Liu, Yilin; Liu, Chang; Jin, Dayao; Jia, Xiaoqiang

    2017-06-25

    We studied the remediation of petroleum-contaminated soils. Two Pseudomonas aeruginosa strains were screened from soil samples in the mine environment. The degradation rate of crude oil was 95.67% after 10 days by mixed culture of the two strains, which was 32% higher than that of single bacterium. It means that the two bacteria had synergistic effect on degrading crude oil. Based on the result, bacterial agent was prepared, and the oil pollution sites were artificially constructed to simulate the degradation of crude oil under different operating conditions. During the experiment, the petroleum hydrocarbon content of the sites after treating with the bacterial agent, decreased obviously in 60 days. The content decreased to among 0.1% and 0.3% from the initial 0.8% per gram of soil. Then, the site with organic manure as supplemental source of carbon and nitrogen had the highest degradation rate of 85.28%, compared to that without adding bacterial agent of only 25.85%.

  13. Photobleaching as a tool to measure the local strain field in fibrous membranes of connective tissues.

    PubMed

    Jayyosi, C; Fargier, G; Coret, M; Bruyère-Garnier, K

    2014-06-01

    Connective tissues are complex structures which contain collagen and elastin fibers. These fiber-based structures have a great influence on material mechanical properties and need to be studied at the microscopic scale. Several microscopy techniques have been developed in order to image such microstructures; among them are two-photon excited fluorescence microscopy and second harmonic generation. These observations have been coupled with mechanical characterization to link microstructural kinematics to macroscopic material parameter evolution. In this study, we present a new approach to measure local strain in soft biological tissues using a side-effect of fluorescence microscopy: photobleaching. Controlling the loss of fluorescence induced by photobleaching, we create a pattern on our sample that we can monitor during mechanical loading. The image analysis allows three-dimensional displacements of the patterns at various loading levels to be computed. Then, local strain distribution is derived using the finite element discretization on a four-node element mesh created from our photobleached pattern. Photobleaching tests on a human liver capsule have revealed that this technique is non-destructive and does not have any impact on mechanical properties. This method is likely to have other applications in biological material studies, considering that all collagen-elastin fiber-based biological tissues possess autofluorescence properties and thus can be photobleached.

  14. Sudden motility reversal indicates sensing of magnetic field gradients in Magnetospirillum magneticum AMB-1 strain

    PubMed Central

    González, Lina M; Ruder, Warren C; Mitchell, Aaron P; Messner, William C; LeDuc, Philip R

    2015-01-01

    Many motile unicellular organisms have evolved specialized behaviors for detecting and responding to environmental cues such as chemical gradients (chemotaxis) and oxygen gradients (aerotaxis). Magnetotaxis is found in magnetotactic bacteria and it is defined as the passive alignment of these cells to the geomagnetic field along with active swimming. Herein we show that Magnetospirillum magneticum (AMB-1) show a unique set of responses that indicates they sense and respond not only to the direction of magnetic fields by aligning and swimming, but also to changes in the magnetic field or magnetic field gradients. We present data showing that AMB-1 cells exhibit sudden motility reversals when we impose them to local magnetic field gradients. Our system employs permalloy (Ni80Fe20) islands to curve and diverge the magnetic field lines emanating from our custom-designed Helmholtz coils in the vicinity of the islands (creating a drop in the field across the islands). The three distinct movements we have observed as they approach the permalloy islands are: unidirectional, single reverse and double reverse. Our findings indicate that these reverse movements occur in response to magnetic field gradients. In addition, using a permanent magnet we found further evidence that supports this claim. Motile AMB-1 cells swim away from the north and south poles of a permanent magnet when the magnet is positioned less than ∼30 mm from the droplet of cells. All together, these results indicate previously unknown response capabilities arising from the magnetic sensing systems of AMB-1 cells. These responses could enable them to cope with magnetic disturbances that could in turn potentially inhibit their efficient search for nutrients. PMID:25478682

  15. Sudden motility reversal indicates sensing of magnetic field gradients in Magnetospirillum magneticum AMB-1 strain.

    PubMed

    González, Lina M; Ruder, Warren C; Mitchell, Aaron P; Messner, William C; LeDuc, Philip R

    2015-06-01

    Many motile unicellular organisms have evolved specialized behaviors for detecting and responding to environmental cues such as chemical gradients (chemotaxis) and oxygen gradients (aerotaxis). Magnetotaxis is found in magnetotactic bacteria and it is defined as the passive alignment of these cells to the geomagnetic field along with active swimming. Herein we show that Magnetospirillum magneticum (AMB-1) show a unique set of responses that indicates they sense and respond not only to the direction of magnetic fields by aligning and swimming, but also to changes in the magnetic field or magnetic field gradients. We present data showing that AMB-1 cells exhibit sudden motility reversals when we impose them to local magnetic field gradients. Our system employs permalloy (Ni(80)Fe(20)) islands to curve and diverge the magnetic field lines emanating from our custom-designed Helmholtz coils in the vicinity of the islands (creating a drop in the field across the islands). The three distinct movements we have observed as they approach the permalloy islands are: unidirectional, single reverse and double reverse. Our findings indicate that these reverse movements occur in response to magnetic field gradients. In addition, using a permanent magnet we found further evidence that supports this claim. Motile AMB-1 cells swim away from the north and south poles of a permanent magnet when the magnet is positioned less than ∼30 mm from the droplet of cells. All together, these results indicate previously unknown response capabilities arising from the magnetic sensing systems of AMB-1 cells. These responses could enable them to cope with magnetic disturbances that could in turn potentially inhibit their efficient search for nutrients.

  16. Constraints on current crustal deformation of the Taiwan plate boundary from CGPS strain rate field and focal mechanism stress inversions

    NASA Astrophysics Data System (ADS)

    Chen, K.; Wu, Y.; Hsu, Y.; Chan, Y.

    2013-12-01

    There are many studies using the continuous GPS (CGPS) observations and forward modeling to represent the current crustal deformation around the global plate boundaries. However, the relation between surface geodetic data and crustal deformation is still a major debate since there are only few available data at depth for constraints. In this study, 3D spatial variations of interseismic surface strain rate and crustal stress state in Taiwan are evaluated by using both CGPS data and earthquake focal mechanisms from 1994 to 2010 and 1991 to 2010, respectively. We estimated strain rate with a simple approach that solves for surface velocity on a 0.1 x 0.1° grid while weighting the distance between observations and each grid node. The surface velocities used in this study are after the process of removing the coseismic and postseismic effects caused by local main shocks. We applied the genetic algorithm in a nonlinear global search for the focal mechanism solution determination with magnitude ranging from ML 1.6 to 7.3 by first motion polarities of P waves. Earthquakes were excluded the redundant aftershock sequences which perturbed the estimation of interseismic stress state. There are 7083 events determined around Taiwan for performing a stress tensor inversion. In the comparison of orientations between strain rate and stress axes, we found the regional variation of stress orientations from surface to the base of crust is significant and not homogenous in Taiwan. In general, the orientations of strain rate and stress axes are consistent from surface to 20 km depth in most of Taiwan regimes. We suggest that the common decoupling phenomenon between both axes starts from 20 km implying a rheological change. The consistency of orientations from strain rate and stress field extends from surface down to more than 30 km in Central Taiwan and southern Coastal Range (COR) could be associated with stress accumulation in the crust for the 1999 Mw 7.6 Chi-Chi and 2003 Mw 6

  17. Small scale field trials of Bacillus sphaericus (strain 2362) against anopheline and culicine mosquito larvae in southern Mexico.

    PubMed

    Arredondo-Jiménez, J I; López, T; Rodríguez, M H; Bown, D N

    1990-06-01

    Experimental breeding sites simulating natural conditions were used to evaluate the efficacy of 2 formulations of Bacillus sphaericus (strain 2362) against Anopheles albimanus and culicine (mostly Culex coronator and Cx. quinquefasciatus) mosquito larvae of southern Mexico. Three doses of each formulation were used in a first field trial: 2, 3 and 4 g/m2 (granular) or 2, 3 and 4 ml/m2 (liquid); and in a second field trial: 0.125, 0.24 and 0.5 g/m2 (granular) or 0.125, 0.25 and 0.5 ml/m2 (liquid). The optimum concentrations of each formulation for effective control of larval populations over periods of 3-4 months were 0.125 ml/m2 of liquid product for Culex spp. and 2 g/m2 of granular product for An. albimanus (ca. 70% mean reduction).

  18. Characterization of High Current RRP(R) Wires as a Function of Magnetic Field, Temperature and Strain

    SciTech Connect

    Godeke, A.; Mentink, M.G.T.; Dietderich, D. R.; den Ouden, A.

    2009-08-16

    A new instrument for the characterization of superconducting materials as a function of Magnetic Field, Temperature and Strain, was designed, constructed and tested at Lawrence Berkeley National Laboratory (LBNL). A U-shaped bending spring was selected, since that design has proven to enable accurate characterizations of a multitude of superconducting materials for more than a decade. The new device is validated though measurements on very high current Rod Restack Processed (RRP) Internal-Tin (IT) wires, for which we will present initial results, including parameterizations of the superconducting phase boundaries and comparisons with other wire types. Accurate parametrization of modern high magnetic field conductors is important for the analysis of the performance of magnet systems.

  19. Enhancing the stability and ecological safety of mass-reared transgenic strains for field release by redundant conditional lethality systems.

    PubMed

    Handler, Alfred M

    2016-04-01

    The genetic manipulation of agriculturally important insects now allows the development of genetic sexing and male sterility systems for more highly efficient biologically-based population control programs, most notably the Sterile Insect Technique (SIT), for both plant and animal insect pests. Tetracycline-suppressible (Tet-off) conditional lethal systems may function together so that transgenic strains will be viable and fertile on a tetracycline-containing diet, but female-lethal and male sterile in tetracycline-free conditions. This would allow their most efficacious use in a unified system for sterile male-only production for SIT. A critical consideration for the field release of such transgenic insect strains, however, is a determination of the frequency and genetic basis of lethality revertant survival. This will provide knowledge essential to evaluating the genetic stability of the lethality system, its environmental safety, and provide the basis for modifications ensuring optimal efficacy. For Tet-off lethal survival determinations, development of large-scale screening protocols should also allow the testing of these modifications, and test the ability of other conditional lethal systems to fully suppress propagation of rare Tet-off survivors. If a dominant temperature sensitive (DTS) pupal lethality system proves efficient for secondary lethality in Drosophila, it may provide the safeguard needed to support the release of sexing/sterility strains, and potentially, the release of unisex lethality strains as a form of genetic male sterility. Should the DTS Prosβ2(1) mutation prove effective for redundant lethality, its high level of structural and functional conservation should allow host-specific cognates to be created for a wide range of insect species. © 2015 Institute of Zoology, Chinese Academy of Sciences.

  20. Inoculation of Acacia mangium with Alginate Beads Containing Selected Bradyrhizobium Strains under Field Conditions: Long-Term Effect on Plant Growth and Persistence of the Introduced Strains in Soil.

    PubMed

    Galiana, A; Prin, Y; Mallet, B; Gnahoua, G M; Poitel, M; Diem, H G

    1994-11-01

    The growth response of Acacia mangium Willd. to inoculation with selected Bradyrhizobium strains was investigated in two field trials in the Ivory Coast (West Africa). In the first trial (Anguededou), four provenances (i.e., trees originating from seeds harvested in different geographical areas) of A. mangium were inoculated with four Bradyrhizobium strains from different origins. Six months after being transplanted in the field, the heights of all inoculated trees showed a statistically significant increase of 9 to 26% compared with those of uninoculated trees, with the most effective strain being Aust 13c. After 19 months, the positive effect of inoculation on tree growth was confirmed. The effect of A. mangium provenance on tree growth was also highly significant. Trees from the Oriomo provenance of Papua New Guinea had a mean height that was 25% greater than those of other provenances. Analysis of variance showed a highly significant effect of interaction between strain and host provenance factors. Thus, most effective strain x provenance combinations could be proposed. Immunological identification of strains clearly showed that 90 to 100% of nodules from trees inoculated with three of the four Bradyrhizobium strains or from uninoculated trees contained exclusively Aust 13c 23 months after tree transplantation. This predominance of Aust 13c in nodules was still observed 42 months after tree transplantation. The second experiment (Port-Bouët), performed with a different soil, confirmed the long-term positive effect of Aust 13c on plant growth, its high competitive ability against indigenous strains, and its persistence in soil. Strain Aust 13c should thus be of great interest for inoculating A. mangium under a wide range of field conditions.

  1. Inoculation of Acacia mangium with Alginate Beads Containing Selected Bradyrhizobium Strains under Field Conditions: Long-Term Effect on Plant Growth and Persistence of the Introduced Strains in Soil

    PubMed Central

    Galiana, Antoine; Prin, Yves; Mallet, Bernard; Gnahoua, Guy-Modeste; Poitel, Mireille; Diem, Hoang Gia

    1994-01-01

    The growth response of Acacia mangium Willd. to inoculation with selected Bradyrhizobium strains was investigated in two field trials in the Ivory Coast (West Africa). In the first trial (Anguededou), four provenances (i.e., trees originating from seeds harvested in different geographical areas) of A. mangium were inoculated with four Bradyrhizobium strains from different origins. Six months after being transplanted in the field, the heights of all inoculated trees showed a statistically significant increase of 9 to 26% compared with those of uninoculated trees, with the most effective strain being Aust 13c. After 19 months, the positive effect of inoculation on tree growth was confirmed. The effect of A. mangium provenance on tree growth was also highly significant. Trees from the Oriomo provenance of Papua New Guinea had a mean height that was 25% greater than those of other provenances. Analysis of variance showed a highly significant effect of interaction between strain and host provenance factors. Thus, most effective strain × provenance combinations could be proposed. Immunological identification of strains clearly showed that 90 to 100% of nodules from trees inoculated with three of the four Bradyrhizobium strains or from uninoculated trees contained exclusively Aust 13c 23 months after tree transplantation. This predominance of Aust 13c in nodules was still observed 42 months after tree transplantation. The second experiment (Port-Bouët), performed with a different soil, confirmed the long-term positive effect of Aust 13c on plant growth, its high competitive ability against indigenous strains, and its persistence in soil. Strain Aust 13c should thus be of great interest for inoculating A. mangium under a wide range of field conditions. PMID:16349430

  2. Identification of nif genes in N2-fixing bacterial strains isolated from rice fields along the Yangtze River Plain.

    PubMed

    Xie, Guang Hui; Cui, Zongjun; Yu, Jun; Yan, Jing; Hai, Weili; Steinberger, Yosef

    2006-01-01

    The aim of this research was to identify nifH and nifHDKYE ' genes in twenty strains of N2-fixing heterotrophic bacteria isolated from rice fields in the Yangtze River Plain. Southern hybridization of the total DNA from each strain was performed with the Klebsiella pneumoniae nifHDKYE ' gene probe (6.2 kb Eco RI fragment from pSA30) and the Azospirillum brasilense nifH gene probe (0.6 kb Eco RI-Hin dIII fragment from pHU8). We found that Eco RI fragments of total DNA from Aeromonas hydrophila HY2, Bacillus azotoformans FD, Bacillus licheniformis NCH1, NCH5, WH4, Bacillus brevis NC2, Bacillus pumilus NC12, Bacillus cereus NCH2, Citrobacter freundii HY5, HY9, Derxia gummosa HZ5, Pseudomonas mendocina HZ1 and Pseudomonas pseudoalcaligenes WH3 were positively hybridized with both of the probes. Agrobacterium radiobacter HY17, Corynebacterium sp. HY12, YZ and Pseudomonas sp. HY11 had Eco RI fragments hybridized with the K. pneumoniae nifHDKYE ' gene probe. An Eco RI fragment of total DNA from Bacillus megaterium YY4 was positively hybridized to the A. brasilense nifH gene probe. No hybridization sign was found in the total DNA fragments from Alcaligenes cupidus YY6 and Corynebacterium sp. NC11 hybridized with either of the gene probes. The data provide the number and size of EcoRI fragments of the total DNA hybridized with the nif gene probes for these strains of rarely studied species, suggesting additional evidence for N2 fixing and nif gene diversity of N2-fixing bacteria in rice fields along the Yangtze River Plain. ((c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  3. Cold and heat strain during cold-weather field training with nuclear, biological, and chemical protective clothing.

    PubMed

    Rissanen, Sirkka; Rintamäki, Hannu

    2007-02-01

    The objective of this study was to quantify the thermal strain of soldiers wearing nuclear, biological, and chemical protective clothing during short-term field training in cold conditions. Eleven male subjects performed marching exercises at moderate and heavy activity levels for 60 minutes. Rectal temperature (Tre), skin temperatures, and heart rate were monitored. Ambient temperature (Ta) varied from -33 to 0 degrees C. Tre was affected by changes in metabolism, rather than in Ta. Tre increased above 38 degrees during heavy exercise even at -33 degrees C. The mean skin temperature decreased to tolerance level (25 degrees C) at Ta below -25 degrees C with moderate exercise. Finger temperature decreased below 15 degrees C (performance degradation) at Ta of -15 degrees C or cooler. The present results from the field confirm the previous results based on laboratory studies and show that risk of both heat and cold strain is evident, with cooling of extremities being most critical, while wearing nuclear, biological, and chemical protective clothing during cold-weather training.

  4. Strain and electric field induced electronic properties of two-dimensional hybrid bilayers of transition-metal dichalcogenides

    SciTech Connect

    Sharma, Munish E-mail: pk-ahluwalia7@yahoo.com; Kumar, Ashok; Ahluwalia, P. K. E-mail: pk-ahluwalia7@yahoo.com; Pandey, Ravindra

    2014-08-14

    Tunability of the electronic properties of two-dimensional bilayer hetero structures of transition-metal dichalcogenides (i.e., MX{sub 2}-M′X′{sub 2} with (M, M′ = Mo, W; X, X′ = S, Se) is investigated. Application of both strain and electric field is found to modify the band gap and carrier effective mass in the hybrid bilayers considered. The calculated results based on density functional theory suggest that the tensile strain considerably changes the band gap of semiconducting bilayers; it makes the band gap to be indirect, and later initiates the semiconductor-to-metal transition. Application of the external electric fields, on the other hand, shows asymmetric variation in the band gap leading to the closure of the gap at about 0.5–1.0 V/Å. Tuning of the band gap and carrier effective mass in such a controlled manner makes the hybrid bilayers of transition metal dichalcogenides to be promising candidates for application in electronic devices at nanoscale.

  5. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation

    NASA Astrophysics Data System (ADS)

    Reinoso, J.; Paggi, M.; Linder, C.

    2017-02-01

    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  6. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation

    NASA Astrophysics Data System (ADS)

    Reinoso, J.; Paggi, M.; Linder, C.

    2017-06-01

    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  7. Genotypes, antibiogram, and pulsed-field gel electrophoresis profiles of Escherichia coli strains from piglets in Korea.

    PubMed

    Lee, Su In; Rayamahji, Nabin; Lee, Won Jung; Cha, Seung Bin; Shin, Min Kyung; Roh, Yu Mi; Yoo, Han Sang

    2009-07-01

    Adherence factors and enterotoxins are major virulence factors of enterotoxigenic Escherichia coli (ETEC). Antibiotics have been used frequently for the treatment and prevention of ETEC infection in piggeries worldwide, including Korea. Therefore, data on both virulence profiles and antibiotic resistance patterns are useful in the epidemiological study of ETEC. A total number of 198 E. coli field isolates were examined. The most prevalent pathotype was F1, followed by a combination of F1 and EAST1. All of the 71 isolates were resistant to more than 2 antibiotics used in a disk diffusion test, and 87.94% of the isolates were found to be resistant to more than 4 antibiotics. Investigations were also conducted to correlate the virulence gene profiles with antibiogram and pulsed-field gel electrophoresis (PFGE). Although a high degree of polymorphism was noted among strains having the same virulence patterns, the highest similarity pattern was observed carrying the same virulence profiles and similar antibiogram. Thus, investigation of both virulence profiles and antibiogram is essential to the epidemiological study of ETEC. Moreover, the PFGE method might be applicable as a tool to reveal genetic relatedness among E. coli strains from piggeries in Korea.

  8. Strain and electric field induced electronic properties of two-dimensional hybrid bilayers of transition-metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.; Pandey, Ravindra

    2014-08-01

    Tunability of the electronic properties of two-dimensional bilayer hetero structures of transition-metal dichalcogenides (i.e., MX2-M'X'2 with (M, M' = Mo, W; X, X' = S, Se) is investigated. Application of both strain and electric field is found to modify the band gap and carrier effective mass in the hybrid bilayers considered. The calculated results based on density functional theory suggest that the tensile strain considerably changes the band gap of semiconducting bilayers; it makes the band gap to be indirect, and later initiates the semiconductor-to-metal transition. Application of the external electric fields, on the other hand, shows asymmetric variation in the band gap leading to the closure of the gap at about 0.5-1.0 V/Å. Tuning of the band gap and carrier effective mass in such a controlled manner makes the hybrid bilayers of transition metal dichalcogenides to be promising candidates for application in electronic devices at nanoscale.

  9. Effects of pulsed magnetic field on the formation of magnetosomes in the Magnetospirillum sp. strain AMB-1.

    PubMed

    Pan, Weidong; Chen, Chuanfang; Wang, Xiaoke; Ma, Qiufeng; Jiang, Wei; Lv, Jing; Wu, Long-Fei; Song, Tao

    2010-04-01

    Magnetotactic bacteria are a diverse group of microorganisms which possess one or more chains of magnetosomes and are endowed with the ability to use geomagnetic fields for direction sensing, thus providing a simple and excellent model for the study of magnetite-based magnetoreception. In this study, a 50 Hz, 2 mT pulsed magnetic field (PMF) was applied to study the effects on the formation of magnetosomes in Magnetospirillum sp. strain AMB-1. The results showed that the cellular magnetism (R(mag)) of AMB-1 culture significantly increased while the growth of cells remained unaffected after exposure. The number of magnetic particles per cell was enhanced by about 15% and slightly increased ratios of magnetic particles of superparamagnetic property (size <20 nm) and mature magnetosomes (size >50 nm) were observed after exposure to PMF. In addition, the intracellular iron accumulation slightly increased after PMF exposure. Therefore, it was concluded that 50 Hz, 2 mT PMF enhances the formation of magnetosomes in Magnetospirillum sp. strain AMB-1. Our results suggested that lower strength of PMF has no significant effects on the bacterial cell morphologies but could affect crystallization process of magnetosomes to some extent. (c) 2009 Wiley-Liss, Inc.

  10. Infection of water buffalo in Rio de Janeiro Brazil with Anaplasma marginale strains also reported in cattle.

    PubMed

    Silva, Jenevaldo B; Cabezas-Cruz, Alejandro; Fonseca, Adivaldo H; Barbosa, José D; de la Fuente, José

    2014-10-15

    Anaplasma marginale is the most prevalent pathogen of cattle in tropical and subtropical regions of the world and causes the disease bovine anaplasmosis. The importance of water buffalo in the world economy is increasing. In addition, while water buffalo may serve as a reservoir host for A. marginale, the susceptibility of this host for A. marginale cattle strains in Brazil has not been reported. The major surface protein 1 alpha (msp1α) gene has been shown to be a stable genetic marker for identification of A. marginale strains. Herein, we analyzed blood samples from 200 water buffalo and identified the A. marginale strains in an endemic area of Rio de Janeiro, Brazil, where ticks were present and water buffalo and cattle co-mingled. Ticks that were feeding on the study buffalo were collected and identified. The prevalence of A. marginale in water buffalo in this study was low (10%). Sequence analysis of the msp1α gene demonstrated the presence of 8 different A. marginale strains. Two A. marginale strains in the water buffalo, (α-β-β-β-Γ) and (α-β-β-Γ), were similar to those reported in cattle from nearby regions. The results of this study suggested that water buffalo in this region are naturally infected with the same strains of A. marginale found in cattle. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Solid Fuel Burning in Steady, Strained, Premixed Flow Fields: The Graphite/Air/Methane System

    NASA Technical Reports Server (NTRS)

    Egolfopoulos, Fokion N.; Wu, Ming-Shin (Technical Monitor)

    2000-01-01

    A detailed numerical investigation was conducted on the simultaneous burning of laminar premixed CH4/air flames and solid graphite in a stagnation flow configuration. The graphite and methane were chosen for this model, given that they are practical fuels and their chemical kinetics are considered as the most reliable ones among solid and hydrocarbon fuels, respectively. The simulation was performed by solving the quasi-one-dimensional equations of mass, momentum, energy, and species. The GRI 2.1 scheme was used for the gas-phase kinetics, while the heterogeneous kinetics were described by a six-step mechanism including stable and radical species. The effects of the graphite surface temperature, the gas-phase equivalence ratio, and the aerodynamic strain rate on the graphite burning rate and NO, production and destruction mechanisms were assessed. Results indicate that as the graphite temperature increases, its burning rate as well as the NO, concentration increase. Furthermore, it was found that by increasing the strain rate, the graphite burning rate increases as a result of the augmented supply of the gas-phase reactants towards the surface, while the NO, concentration decreases as a result of the reduced residence time. The effect of the equivalence ratio on both the graphite burning rate and NO, concentration was found to be non-monotonic and strongly dependent on the graphite temperature. Comparisons between results obtained for a graphite and a chemically inert surface revealed that the chemical activity of the graphite surface can result to the reduction of NO through reactions of the CH3, CH2, CH, and N radicals with NO.

  12. Vaccine-strain herpes zoster found in the trigeminal nerve area in a healthy child: A case report.

    PubMed

    Iwasaki, Sayaka; Motokura, Kouji; Honda, Yoshitaka; Mikami, Masamitsu; Hata, Daisuke; Hata, Atsuko

    2016-12-01

    A previously healthy 2-year-old girl, vaccinated for varicella at 17 months, was admitted because of left-sided facial herpes zoster caused by vaccine-strain varicella-zoster virus (VZV). She recovered fully with no complication after intravenous treatment using acyclovir. Earlier reports have described that herpes zoster (HZ) rashes caused by vaccine-strain VZV tend to occur on the dermis corresponding to the skin area where the varicella vaccine was received. However, rashes appeared on this girl only in the trigeminal nerve area, which is unrelated to the vaccinated site. Results underscore the importance of distinguishing vaccine-strain VZV from wild-type VZV whenever encountering HZ cases after vaccination, even in immunocompetent children, irrespective of the skin lesion site. Monitoring vaccine-strain HZ incidence rates is expected to elucidate many aspects of varicella vaccine safety.

  13. First case report of non-human primates (Alouatta clamitans) with the hypervirulent Klebsiella pneumoniae serotype K1 strain ST 23: A possible emerging wildlife pathogen.

    PubMed

    Anzai, Eleine Kuroki; Souza Júnior, Júlio César de; Peruchi, Amanda Rezende; Fonseca, Juliana Mello; Gumpl, Elke Kreuscher; Pignatari, Antônio Carlos Campos; Hirano, Zelinda Maria Braga; Silveira, Alessandro Conrado de Oliveira

    2017-08-15

    Hypervirulent strain of Klebsiella pneumoniae genotype K1 isolates have recently emerged, causing severe pyogenic liver abscess complicated by devastating metastatic infections in humans. We describe a short outbreak of the non-human primate (NHP) research center, associated with a hypervirulent K. pneumoniae. The genetic similarity of the strains was evaluated by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) techniques, and virulence encoding genes were detected by polymerase chain reaction (PCR). The isolates were phenotypically like strains causing community-acquired invasive liver abscess syndrome in humans. All strains exhibited identical PFGE patterns and were found to belong to ST23 and presented a hypermucovisity phenotype and possessed magA and rmpA gene. This is the first case report of NHPs caused by K. pneumoniae displaying a hypermucoviscosity phenotype and belonging to capsular serotypes K1 and ST23. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Identification and characterization of Clostridium botulinum group III field strains by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS).

    PubMed

    Bano, Luca; Drigo, Ilenia; Tonon, Elena; Pascoletti, Simone; Puiatti, Cinzia; Anniballi, Fabrizio; Auricchio, Bruna; Lista, Florigio; Montecucco, Cesare; Agnoletti, Fabrizio

    2017-08-10

    Animal botulism is primarily due to botulinum neurotoxin (BoNT) types C, D or their chimeric variants C/D or D/C, produced by Clostridium botulinum group III, which appears to include the genetically indistinguishable Clostridium haemolyticum and Clostridium novyi. In the present study, we used matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI TOF MS) to identify and characterize 81 BoNT-producing Clostridia isolated in 47 episodes of animal botulism. The instrument's default database, containing no entries for Clostridium botulinum, permitted reliable identification of 26 strains at the genus level. Although supplementation of the database with reference strains enhanced the instrument's ability to identify the neurotoxic strains at the genus level, resolution was not sufficient to recognize field strains at species level. Characterization by MALDI TOF confirmed the well-documented phenotypic and genetic differences between Clostridium botulinum strains of serotypes normally implicated in human botulism (A, B, E, F) and other Clostridium species able to produce BoNTs type C and D. The chimeric and non-chimeric field strains grouped separately. In particular, very low similarity was found between two non-chimeric type C field strains isolated in the same outbreak and the other field strains. This difference was comparable with the differences among the various Clostridia species included in the study. Characterization by MALDI TOF confirmed that BoNT-producing Clostridia isolated from animals are closely related and indistinguishable at the species level from Clostridium haemolyticum and Clostridium novyi reference strains. On the contrary, there seem to be substantial differences among chimeric and some non-chimeric type C strains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Effect of electric field and strain on the magnetic properties of phase separated manganites

    NASA Astrophysics Data System (ADS)

    Grant, Daniel M.

    Perovskite manganese oxide (manganites) have attracted research attention due to a wide variety of complex behaviors observed, including colossal responses to external perturbations. More recent work has focused on the competing ground states and the coexistence of magnetic and non-magnetic phases in manganites. Anisotropic resistance changes have been observed in high quality thin film manganites, possibly due to dielectrophoresis, upon application of an electric field. Dielectrophoresis is usually observed in fluid-like systems in an electric field but is surprisingly useful in explaining the transport properties of manganites due to the fluid-like behavior of competing phases. A main goal of this dissertation is to explore the role of magnetic interactions on the dielectrophoresis effects on ferromagnetic metallic regions in phase separated manganite thin films. The combined effect of electric and magnetic fields in these manganites could reveal a novel form of magnetoelectric effect. In one set of experiments, a magnetic field decreased the amount of time needed for the dielectrophoresis to lead to a large drop in the resistance along one direction, showing the importance of magnetic interactions in dielectrophoresis. In another set of experiments, breaking down the large resistance of a manganite sample produced a small change in coercive field, further confirming the relationship between electric and magnetic effects in manganites. However, the largest effect on the magnetic properties of the thin films was from confinement of the competing phases in micrometer scale structures fabricated on the thin films. Coercive field increases of about 100- 400% were observed in a certain range of film thicknesses. To analyze such behavior in manganites, high quality thin films of the phase-separated manganite (La1-xPrx)1-yCa yMnO3 (LPCMO) were grown on NdGaO3 (NGO) substrates using pulsed laser deposition. Mangetotransport, magnetization, and scanning probe microscopy

  16. Review of group A rotavirus strains reported in swine and cattle.

    PubMed

    Papp, Hajnalka; László, Brigitta; Jakab, Ferenc; Ganesh, Balasubramanian; De Grazia, Simona; Matthijnssens, Jelle; Ciarlet, Max; Martella, Vito; Bányai, Krisztián

    2013-08-30

    Group A rotavirus (RVA) infections cause severe economic losses in intensively reared livestock animals, particularly in herds of swine and cattle. RVA strains are antigenically heterogeneous, and are classified in multiple G and P types defined by the two outer capsid proteins, VP7 and VP4, respectively. This study summarizes published literature on the genetic and antigenic diversity of porcine and bovine RVA strains published over the last 3 decades. The single most prevalent genotype combination among porcine RVA strains was G5P[7], whereas the predominant genotype combination among bovine RVA strains was G6P[5], although spatiotemporal differences in RVA strain distribution were observed. These data provide important baseline data on epidemiologically important