WorldWideScience

Sample records for vgnki strain bor-74

  1. Strain Gage

    Science.gov (United States)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  2. Muscle strain treatment

    Science.gov (United States)

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  3. Muscle strain (image)

    Science.gov (United States)

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  4. Strains and Sprains

    Science.gov (United States)

    ... long winter off might lead to a strained calf or thigh muscle. Sprains are caused by injuries, such as twisting your ankle. This kind of injury is common in sports, but can also happen any time you trip or fall. What if I Get a Strain or Sprain? If you get a strain or ...

  5. Obturator internus muscle strains

    OpenAIRE

    Byrne, Caoimhe; Alkhayat, Abdullah; O'Neill, Pat; Eustace, Stephen; Kavanagh, Eoin

    2017-01-01

    We report 2 cases of obturator internus muscle strains. The injuries occurred in young male athletes involved in kicking sports. Case 1 details an acute obturator internus muscle strain with associated adductor longus strain. Case 2 details an overuse injury of the bilateral obturator internus muscles. In each case, magnetic resonance imaging played a crucial role in accurate diagnosis.

  6. Obturator internus muscle strains.

    Science.gov (United States)

    Byrne, Caoimhe; Alkhayat, Abdullah; O'Neill, Pat; Eustace, Stephen; Kavanagh, Eoin

    2017-03-01

    We report 2 cases of obturator internus muscle strains. The injuries occurred in young male athletes involved in kicking sports. Case 1 details an acute obturator internus muscle strain with associated adductor longus strain. Case 2 details an overuse injury of the bilateral obturator internus muscles. In each case, magnetic resonance imaging played a crucial role in accurate diagnosis.

  7. Obturator internus muscle strains

    Directory of Open Access Journals (Sweden)

    Caoimhe Byrne, MB BCh, BAO

    2017-03-01

    Full Text Available We report 2 cases of obturator internus muscle strains. The injuries occurred in young male athletes involved in kicking sports. Case 1 details an acute obturator internus muscle strain with associated adductor longus strain. Case 2 details an overuse injury of the bilateral obturator internus muscles. In each case, magnetic resonance imaging played a crucial role in accurate diagnosis.

  8. Strain-engineered MOSFETs

    CERN Document Server

    Maiti, CK

    2012-01-01

    Currently strain engineering is the main technique used to enhance the performance of advanced silicon-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Written from an engineering application standpoint, Strain-Engineered MOSFETs introduces promising strain techniques to fabricate strain-engineered MOSFETs and to methods to assess the applications of these techniques. The book provides the background and physical insight needed to understand new and future developments in the modeling and design of n- and p-MOSFETs at nanoscale. This book focuses on recent developments in st

  9. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction. The reinforce......The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

  10. Chitinase producing Bt strains

    Science.gov (United States)

    Haim B. Gunner; Matthew Zimet; Sarah Berger

    1985-01-01

    Screening of 402 strains of more than 18 varieties of Bacillus thuringiensis showed chitinase to be inducible in virtually every serovar tested. Though the chitinase titre varied among strains, there was a strong correlation between enhanced lethality to spruce budworm, Choristoneura fumiferana (Clemens), and an increase in...

  11. The strained state cosmology

    CERN Document Server

    Tartaglia, Angelo

    2015-01-01

    Starting from some relevant facts concerning the behaviour of the universe over large scale and time span, the analogy between the geometric approach of General Relativ- ity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time repro- duces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theor...

  12. Hamstring strain - aftercare

    Science.gov (United States)

    ... does not seem to be healing as expected. Alternative Names Pulled hamstring muscle; Sprain - hamstring References Ali K, Leland JM. Hamstring strains and tears in the athlete. Clin Sports Med . 2012;31(2):263-272. PMID: 22341016 ...

  13. Psychological strain between nurses

    Directory of Open Access Journals (Sweden)

    Andrea Obročníková

    2015-12-01

    Full Text Available Aim: The aim of the study was to identify differences in perception of work (mental workload among nurses providing acute and chronic nursing care. Design: Study design is cross-sectional and descriptive. Methods: The sample of respondents consisted of 97 nurses working in departments Neurology, Anesthesiology and Intensive Care Unit of the hospital St. James in Bardejov, University Hospital of L. Pasteur in Košice and University Hospital J. A. Reiman in Prešov. To measure psychological strain, Meister's questionnaire for neuropsychological strain was used. Results: Increased psychological strain was observed in nurses providing acute care versus nurses providing chronic care, particularly in job satisfaction, long-term tolerance, time constraints, high responsibility, nervousness, fatigue and satiety. In comparison with the population norm, nurses in acute care achieved significantly higher indicators of factor I (strain and gross score as nurses in neurological care. A statistically significant relationship between psychological stress and age of nurses working in anesthesiology and intensive care departments was confirmed. Nurses with long term practical experience are exposed to intense mental stress (especially in the areas of strain and monotony. Conclusion: The results of our study suggest the reality that variable qualities of work related strain among nurses can lead to physical and emotional exhaustion.

  14. Strain: Fact or Fiction?

    Science.gov (United States)

    Heilbronner, Renée

    2017-04-01

    2017 marks the 50th anniversary of the publication of John Ramsay's well known textbook "Folding and Fracturing of Rocks" - ... and the 30th anniversary of the rejection of a rather less well known paper entitled "Strain: Fact or Fiction?" submitted by Renée Panozzo to the Journal of Structural Geology. The gist of the paper was simple and straight forward: it was argued that not every fabric that can be observed in deformed rocks is necessarily a measure of the amount of strain the rock incurred. A distinction was made between a general "fabric", i.e., the traceable geometry of grain boundaries, for example, and a so-called "strain fabric", i.e., the model geometry that would result from homogeneously straining an initially isotropic fabric and that would exhibit at least orthorhombic symmetry. To verify if a given fabric was indeed a strain fabric it was therefore suggested to use the SURFOR method (published by Panozzo) and to carry out a so-called strain test, i.e., a check of symmetry, before interpreting the results of a fabric analysis in terms of strain. The problem with the paper was that it was very obviously written out of frustration. The frustration came form having reviewed a number of manuscripts which tried to use the then novel SURFOR method for strain analysis without first checking if the the fabric was a indeed a "strain fabric" or not, and then blaming the SURFOR method for producing ambiguous results. As a result, the paper was not exactly well balanced and carefully thought out. It was considered "interesting but not scholarly" by one of the reviewers and down-right offensive by the second. To tell the truth, however, the paper was not formally rejected. The editor Sue Treagus strongly encouraged Panozzo to revise the paper, ... and 30 years later, I will follow her advise and offer a revised paper as a tribute to John Ramsay. To quote from the original manuscript: "We should be a little more impressed that strain works so well, and less

  15. Running Title: Strained Yoghurts

    African Journals Online (AJOL)

    USER

    2012-09-27

    Sep 27, 2012 ... prebiotics (inulin and oligofructose) added in different ratios. Al Otaibi and El Demerdash (2008) investigated the quality and shelf life of concentrated yoghurt (labneh) by the addition of some essential oils. Şenel et al. (2009) also determined some compounds affecting aroma and flavour of strained yoghurt ...

  16. LAOS: The strain softening/strain hardening paradox

    NARCIS (Netherlands)

    Mermet-Guyennet, M.R.B.; de Castro, J.G.; Habibi, M.; Martzel, N.; Denn, M.M.; Bonn, D.

    2015-01-01

    Numerous materials, from biopolymers to filled rubbers, exhibit strain softening at high strain amplitudes during a strain sweep in oscillatory rheology: The modulus decreases with increasing deformation. On the other hand, if the nonlinear elastic response is analyzed within a single oscillation

  17. Strain measurement based battery testing

    Science.gov (United States)

    Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

    2017-05-23

    A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

  18. Strain gradients in epitaxial ferroelectrics

    NARCIS (Netherlands)

    Catalan, G; Noheda, Beatriz; McAneney, J; Sinnamon, LJ; Gregg, JM

    2005-01-01

    X-ray analysis of ferroelectric thin layers of Ba1/2Sr1/2TiO3 with different thicknesses reveals the presence of strain gradients across the films and allows us to propose a functional form for the internal strain profile. We use this to calculate the influence of strain gradient, through

  19. Strain incompatibility and residual strains in ferroelectric single crystals.

    Science.gov (United States)

    Pramanick, A; Jones, J L; Tutuncu, G; Ghosh, D; Stoica, A D; An, K

    2012-01-01

    Residual strains in ferroelectrics are known to adversely affect the material properties by aggravating crack growth and fatigue degradation. The primary cause for residual strains is strain incompatibility between different microstructural entities. For example, it was shown in polycrystalline ferroelectrics that residual strains are caused due to incompatibility between the electric-field-induced strains in grains with different crystallographic orientations. However, similar characterization of cause-effect in multidomain ferroelectric single crystals is lacking. In this article, we report on the development of plastic residual strains in [111]-oriented domain engineered BaTiO(3) single crystals. These internal strains are created due to strain incompatibility across 90° domain walls between the differently oriented domains. The average residual strains over a large crystal volume measured by in situ neutron diffraction is comparable to previous X-ray measurements of localized strains near domain boundaries, but are an order of magnitude lower than electric-field-induced residual strains in polycrystalline ferroelectrics.

  20. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid (101) positioned on the carrier layer, wherein the measurement grid comprises a number of measurement grid sections placed side by side with gaps in between, and a number of end loops (106) interconnecting...... the measurement grid sections at their ends. The end loops at both ends of the measurement grid extend a length (L, 500) in the axial direction in millimetres of a factor times a ratio between a width of a grid section and the gap distance, wherein the factor is larger or equal to 1.5. The invention further...

  1. Reconstruction of axisymmetric strain distributions via neutron strain tomography

    Energy Technology Data Exchange (ETDEWEB)

    Abbey, Brian, E-mail: b_abbey80@yahoo.co.uk [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); ARC Centre of Excellence for Coherent X-ray Science, School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Zhang Shuyan [Rutherford Appleton Laboratory, ISIS Facility, Chilton OX11 0QX (United Kingdom); Vorster, Wim; Korsunsky, Alexander M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom)

    2012-01-01

    Predicting the behaviour of structural components under a particular set of loading conditions requires knowledge of the residual elastic strain distribution throughout the bulk of these components. Characterising the 3D strain state at any particular point involves the measurement of six independent components which make up the second order strain tensor. Mapping the complete strain distribution throughout large volumes thus presents significant practical challenges. One possible solution to this problem is to reconstruct the 3D variation of strain components using tomographic techniques. The basic principle underpinning this idea is that the multi-component strain tensor can be reconstructed from a redundant set of lower order projection data. Here we demonstrate this fundamental concept for two samples: a shrink fit 'ring-and-plug' sample, and a spray-quenched circular cylinder, both possessing axially symmetric internal strain distribution. We present and contrast different approaches to the strain tomography problem. The methods described here can also be readily applied to high-energy X-ray diffraction measurements and represent an important step toward developing the tomographic reconstruction framework for strain tensor distributions of arbitrary complexity. The major benefit of neutron strain tomography is that the incident beam flux is utilised more fully, greatly reducing the data collection times. Using micro-channel plate (MCP) neutron detectors, a spatial resolution of the order of 0.1 mm can be achieved .

  2. Colony Dimorphism in Bradyrhizobium Strains

    Science.gov (United States)

    Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

    1988-01-01

    Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

  3. Hydrogen production from microbial strains

    Science.gov (United States)

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  4. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...... to uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

  5. Adductor muscle strains in sport.

    Science.gov (United States)

    Nicholas, Stephen J; Tyler, Timothy F

    2002-01-01

    An in-season adductor muscle strain may be debilitating for the athlete. Furthermore, an adductor strain that is treated improperly could become chronic and career threatening. Any one of the six muscles of the adductor group could be involved. The degree of injury can range from a minor strain (Grade I), where minimal playing time is lost, to a severe strain (Grade III) in which there is complete loss of muscle function. Ice hockey and soccer players seem particularly susceptible to adductor muscle strains. In professional ice hockey players throughout the world, approximately 10% of all injuries are groin strains. These injuries, which have been linked to hip muscle weakness, previous injuries to that area, preseason practice sessions and level of experience, may be preventable if such risk factors can be addressed before each season. Hip-strengthening exercises were shown to be an effective method of reducing the incidence of adductor strains in one closely followed National Hockey League ice hockey team. Despite the identification of risk factors and strengthening intervention for ice hockey players, adductor strains continue to occur throughout sport. Clinicians feel an active training programme, along with completely restoring the strength of the adductor muscle group, is the key to successful rehabilitation. Surgical intervention is available if nonoperative treatment fails for 6 months or longer. Adductor release and tenotomy was reported to have limited success in athletes.

  6. Piezoelectric strain modulation in FETs

    NARCIS (Netherlands)

    van Hemert, T.; Hueting, Raymond Josephus Engelbart

    2013-01-01

    We report on a feature for the transistor, a piezoelectric layer to modulate the strain in the channel. The strain is proportional to the gate-source voltage, and thus increases as the device is turned on. As a result, the device has the leakage current of a relaxed device and the lower threshold

  7. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... circumstances both materials show good bonding, but the high purity material is excluded because of recrystallisation and the resulting loss of mechanical properties. The effect of cross stacking and roll bonding pre-strained sheets of the commercial purity material is investigated and some dependence...

  8. Low TCR nanocomposite strain gages

    Science.gov (United States)

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  9. Effective Hamiltonian of strained graphene

    Science.gov (United States)

    Linnik, T. L.

    2012-05-01

    Based on the symmetry properties of the graphene lattice, we derive the effective Hamiltonian of graphene under spatially nonuniform acoustic and optical strains. Comparison with the published results of the first-principles calculations allows us to determine the values of some Hamiltonian parameters, and suggests the validity of the derived Hamiltonian for acoustical strain up to 10%. The results are generalized for the case of graphene with broken plane reflection symmetry, which corresponds, for example, to the case of graphene placed on a substrate. Here, essential modifications to the Hamiltonian give rise, in particular, to the gap opening in the spectrum in the presence of the out-of-plane component of optical strain, which is shown to be due to the lifting of the sublattice symmetry. The developed effective Hamiltonian can be used as a convenient tool for analysis of a variety of strain-related effects, including electron-phonon interaction or pseudo-magnetic fields induced by the nonuniform strain.

  10. Taxonomy of oxalotrophic Methylobacterium strains

    Science.gov (United States)

    Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

    2008-10-01

    Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

  11. Strained-layer electronics and optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Myers, D.R.

    1990-01-01

    Strained-layer epitaxy involves more than the dislocation-free growth of dissimilar materials: effective strained-layer epitaxy exploits lattice-mismatch-induced strain to fine-tune material properties. This paper describes strained-layer epitaxy and describes its application to electronic and optoelectronic device to improve performance.

  12. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Science.gov (United States)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  13. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...

  14. Job strain and tobacco smoking

    DEFF Research Database (Denmark)

    Heikkilä, Katriina; Nyberg, Solja T; Fransson, Eleonor I

    2012-01-01

    Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job...... strain, is associated with tobacco smoking in working adults....

  15. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    Science.gov (United States)

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  16. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale.......A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...

  17. Strain-Detecting Composite Materials

    Science.gov (United States)

    Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

    2016-01-01

    A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

  18. Strain Monitoring of Flexible Structures

    Science.gov (United States)

    Litteken, Douglas A.

    2017-01-01

    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  19. Strain stiffening in collagen I networks.

    Science.gov (United States)

    Motte, Stéphanie; Kaufman, Laura J

    2013-01-01

    Biopolymer gels exhibit strain stiffening that is generally not seen in synthetic gels. Here, we investigate the strain-stiffening behavior in collagen I gels that demonstrate elasticity derived from a variety of sources including crosslinking through telopeptides, bundling through low-temperature gelation, and exogenous crosslinking with genipin. In all cases, it is found that these gels exhibit strain stiffening; in general, onset of strain stiffening occurs earlier, yield strain is lower, and degree of strain stiffening is smaller in higher concentration gels and in those displaying thick fibril bundles. Recovery after exposure to high strains is substantial and similar in all gels, suggesting that much of the stiffening comes from reversible network deformations. A key finding of this study is that collagen I gels of identical storage and loss moduli may display different nonlinear responses and different capacities to recover from high strain. Copyright © 2012 Wiley Periodicals, Inc.

  20. Role strain in occupational therapy fieldwork educators.

    Science.gov (United States)

    Barton, Rebecca; Corban, Ashley; Herrli-Warner, Lauren; McClain, Emily; Riehle, Danielle; Tinner, Eboni

    2013-01-01

    The purpose of this study was to determine if occupational therapy fieldwork educators are experiencing role strain. Were recruited from a convenience sample of a university database of 315 fieldwork sites. The Role Strain in Occupational Therapy Fieldwork Educators Inventory was used to gather qualitative and quantitative data about practice. The overall mean for role strain was 2.34/5 with a 73% return rate. The majority of participants fell into the moderate to low role strain category. Individuals with 5-10 years of practice had the greatest amount of role strain (2.43, SD 0.51, n=60). Participants working in pediatric settings had role strain in the moderate range. Nine items emerged with the highest amount of role strain, such as coping with job expectations and inadequate time to meet role expectations. Creation of strategies to reduce role strain should be a priority in our changing healthcare environment.

  1. Piezoelectric field in strained GaAs.

    Energy Technology Data Exchange (ETDEWEB)

    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. Intraspecies genotypic heterogeneity among Mycoplasma gallisepticum strains.

    OpenAIRE

    Santha, M; Lukacs, K; Burg, K; Bernath, S; Rasko, I; Stipkovits, L.

    1988-01-01

    The DNA cleavage patterns and protein profiles of six Mycoplasma gallisepticum strains from various parts of the world were compared. Obvious differences among the strains were obtained by DNA restriction analysis. Reflection of genotypic variations in the polypeptide patterns was less pronounced; slight differences in the protein profiles of the strains were found. The data presented here indicate that some intraspecies polymorphism exists among M. gallisepticum strains.

  3. Intraspecies genotypic heterogeneity among Mycoplasma gallisepticum strains.

    Science.gov (United States)

    Santha, M; Lukacs, K; Burg, K; Bernath, S; Rasko, I; Stipkovits, L

    1988-01-01

    The DNA cleavage patterns and protein profiles of six Mycoplasma gallisepticum strains from various parts of the world were compared. Obvious differences among the strains were obtained by DNA restriction analysis. Reflection of genotypic variations in the polypeptide patterns was less pronounced; slight differences in the protein profiles of the strains were found. The data presented here indicate that some intraspecies polymorphism exists among M. gallisepticum strains. PMID:2895605

  4. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Science.gov (United States)

    Gangaiah, Dharanesh; Webb, Kristen M; Humphreys, Tricia L; Fortney, Kate R; Toh, Evelyn; Tai, Albert; Katz, Samantha S; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A; Munson, Robert S; Spinola, Stanley M

    2015-01-01

    Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  5. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

    Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  6. Phenotypic characterization of Lactobacillus strains isolated from ...

    African Journals Online (AJOL)

    Thirty three strains of Lactobacillus were isolated from human milk and infant faeces, animal (cow and goat) milks and from plants (Anagalis arvensis and Bromus mango species). The various strains were identified based on phenotypic tests. Amongst them, 12 strains belonged to group 1, which comprised L. acidophilus, ...

  7. CONDITIONS FOR DEVELOPMENT DYNAMIC STRAIN STEEL AGEING

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2010-12-01

    Full Text Available Contrary to the one-sided straining, after compressive predeformation with subsequent tension the shift of appearing the first stress stall to higher values of strains can be observed. The values of compressive predeformation and the strain of first stress stall appearance are approximately equal.

  8. The characterization of African strains of capripoxvirus.

    OpenAIRE

    Kitching, R. P.; Bhat, P. P.; Black, D. N.

    1989-01-01

    Isolates of capripoxvirus collected from sub-Saharan Africa were compared in sheep, goats and cattle and by restriction endonuclease digestion of their purified DNA. Biochemical techniques were used to precisely identify strains of capripoxvirus for epidemiological investigations. Strains of capripoxvirus infecting cattle have remained very stable over a 30-year period and are closely related to strains recovered from sheep in Africa.

  9. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads

    2008-01-01

    of the piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity...

  10. Job Strain in Physical Therapists

    Science.gov (United States)

    Campo, Marc A.; Weiser, Sherri; Koenig, Karen L.

    2009-01-01

    Background: Job stress has been associated with poor outcomes. In focus groups and small-sample surveys, physical therapists have reported high levels of job stress. Studies of job stress in physical therapy with larger samples are needed. Objective: The purposes of this study were: (1) to determine the levels of psychological job demands and job control reported by physical therapists in a national sample, (2) to compare those levels with national norms, and (3) to determine whether high demands, low control, or a combination of both (job strain) increases the risk for turnover or work-related pain. Design: This was a prospective cohort study with a 1-year follow-up period. Methods: Participants were randomly selected members of the American Physical Therapy Association (n=882). Exposure assessments included the Job Content Questionnaire (JCQ), a commonly used instrument for evaluation of the psychosocial work environment. Outcomes included job turnover and work-related musculoskeletal disorders. Results: Compared with national averages, the physical therapists reported moderate job demands and high levels of job control. About 16% of the therapists reported changing jobs during follow-up. Risk factors for turnover included high job demands, low job control, job strain, female sex, and younger age. More than one half of the therapists reported work-related pain. Risk factors for work-related pain included low job control and job strain. Limitations: The JCQ measures only limited dimensions of the psychosocial work environment. All data were self-reported and subject to associated bias. Conclusions: Physical therapists’ views of their work environments were positive, including moderate levels of demands and high levels of control. Those therapists with high levels of demands and low levels of control, however, were at increased risk for both turnover and work-related pain. Physical therapists should consider the psychosocial work environment, along with other

  11. Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group

    DEFF Research Database (Denmark)

    Jensen, L.; Petersen, E.; Henriksen, S.A.

    1998-01-01

    Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain restricted markers. Strain restriction extended beyond discrimination of the 119 and RH...

  12. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, T K; Bonde, J P

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  13. Strain-dependent norovirus bioaccumulation in oysters.

    Science.gov (United States)

    Maalouf, Haifa; Schaeffer, Julien; Parnaudeau, Sylvain; Le Pendu, Jacques; Atmar, Robert L; Crawford, Sue E; Le Guyader, Françoise S

    2011-05-01

    Noroviruses (NoVs) are the main agents of gastroenteritis in humans and the primary pathogens of shellfish-related outbreaks. Some NoV strains bind to shellfish tissues by using carbohydrate structures similar to their human ligands, leading to the hypothesis that such ligands may influence bioaccumulation. This study compares the bioaccumulation efficiencies and tissue distributions in oysters (Crassostrea gigas) of three strains from the two principal human norovirus genogroups. Clear differences between strains were observed. The GI.1 strain was the most efficiently concentrated strain. Bioaccumulation specifically occurred in digestive tissues in a dose-dependent manner, and its efficiency paralleled ligand expression, which was highest during the cold months. In comparison, the GII.4 strain was very poorly bioaccumulated and was recovered in almost all tissues without seasonal influence. The GII.3 strain presented an intermediate behavior, without seasonal effect and with less bioaccumulation efficiency than that of the GI.1 strain during the cold months. In addition, the GII.3 strain was transiently concentrated in gills and mantle before being almost specifically accumulated in digestive tissues. Carbohydrate ligand specificities of the strains at least partly explain the strain-dependent bioaccumulation characteristics. In particular, binding to the digestive-tube-specific ligand should contribute to bioaccumulation, whereas we hypothesize that binding to the sialic acid-containing ligand present in all tissues would contribute to retain virus particles in the gills or mantle and lead to rapid destruction.

  14. Graphene electronics via strain engineering

    Science.gov (United States)

    Pereira, Vitor

    2009-03-01

    Recently, graphene has been confirmed as the strongest material ever measured, being able to sustain reversible deformations in excess of 20%. These mechanical measurements arise at a time where graphene draws considerable attention on account of its unusual and rich electronic properties. Besides the great crystalline quality, high mobility and resilience to high current densities, they include a strong field effect, absence of backscattering and a minimum metallic conductivity. While many such properties might prove instrumental if graphene is to be used in future technological applications in the ever pressing demand for miniaturization in electronics, the latter is actually a strong deterrent: it hinders the pinching off of the charge flow and the creation of quantum point contacts. In addition, graphene has a gapless spectrum with linearly dispersing, Dirac-like, excitations. Although a gap can be induced by means of quantum confinement in the form of nanoribbons and quantum dots, these ``paper-cutting'' techniques are prone to edge roughness, which has detrimental effects on the electronic properties. We explore an alternative route for tailoring the electronic structure of graphene, based on a strain engineering. We will discuss how local and global strain profiles can be suitably tailored to impact the bandstructure of graphene and control its transport characteristics. Electron confinement, electron beam collimation, energy filtering, surface modes and bulk spectral gaps are some examples of what might be achieved.

  15. Strain engineering of van der Waals heterostructures.

    Science.gov (United States)

    Vermeulen, Paul A; Mulder, Jefta; Momand, Jamo; Kooi, Bart J

    2018-01-18

    Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS2, and Bi2Te3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals interfaces. Here we present direct observations of the contrary by showing growth of vdWaals heterostructures with persistent in-plane strains up to 5% and we show that strain relaxation follows a not yet reported process distinctly different from strain relaxation in three-dimensionally bonded (3D) materials. For this, 2D bonded Bi2Te3-Sb2Te3 and 2D/3D bonded Bi2Te3-GeTe multilayered films are grown using Pulsed Laser Deposition (PLD) and their structure is monitored in situ using Reflective High Energy Electron Diffraction (RHEED) and post situ analysis is performed using Transmission Electron Microscopy (TEM). Strain relaxation is modeled and found to solely depend on the layer being grown and its initial strain. This insight demonstrates that strain engineering of 2D bonded heterostructures obeys different rules than hold for epitaxial 3D materials and opens the door to precise tuning of the strain state of the individual layers to optimize functional performance of vdWaals heterostructures.

  16. Determining Micromechanical Strain in Nitinol

    Energy Technology Data Exchange (ETDEWEB)

    Strasberg, Matthew; /SLAC

    2006-09-27

    Nitinol is a superelastic alloy made of equal parts nickel and titanium. Due to its unique shape memory properties, nitinol is used to make medical stents, lifesaving devices used to allow blood flow in occluded arteries. Micromechanical models and even nitinol-specific finite element analysis (FEA) software are insufficient for unerringly predicting fatigue and resultant failure. Due to the sensitive nature of its application, a better understanding of nitinol on a granular scale is being pursued through X-ray diffraction techniques at the Stanford Synchrotron Radiation Laboratory (SSRL) at the Stanford Linear Accelerator Center (SLAC). Through analysis of powder diffraction patterns of nitinol under increasing tensile loads, localized strain can be calculated. We compare these results with micromechanical predictions in order to advance nitinol-relevant FEA tools. From this we hope to gain a greater understanding of how nitinol fatigues under multi-axial loads.

  17. Mechanical properties of biaxially strained poly(L-lactide) tubes: Strain rate and temperature dependence

    DEFF Research Database (Denmark)

    Løvdal, Alexandra Liv Vest; Andreasen, Jens Wenzel; Mikkelsen, Lars Pilgaard

    2017-01-01

    their Tg for improvement of their strength, in a two-step process (sequential straining). Mechanical properties and crystal morphology were investigated as a function of processing strain rate and temperature. DSC revealed that a low processing strain rate allows molecular chain relaxation in the direction...... of strain and the crystallization is suppressed. Faster strain rates on the other hand suppress chain relaxation, and results in crystalline tubes. The mechanical properties are influenced by both processing strain rate and temperature. Low strain rates allow chain relaxation resulting in the lowest...... strength and stiffness, whereas a larger stiffness and strength is achieved by increasing strain rate and temperature. Isotropic mechanical properties are only observed at high processing strain rates....

  18. Noninvasive characterization of carotid plaque strain.

    Science.gov (United States)

    Khan, Amir A; Sikdar, Siddhartha; Hatsukami, Thomas; Cebral, Juan; Jones, Michael; Huston, John; Howard, George; Lal, Brajesh K

    2017-06-01

    Current risk stratification of internal carotid artery plaques based on diameter-reducing percentage stenosis may be unreliable because ischemic stroke results from plaque disruption with atheroembolization. Biomechanical forces acting on the plaque may render it vulnerable to rupture. The feasibility of ultrasound-based quantification of plaque displacement and strain induced by hemodynamic forces and their relationship to high-risk plaques have not been determined. We studied the feasibility and reliability of carotid plaque strain measurement from clinical B-mode ultrasound images and the relationship of strain to high-risk plaque morphology. We analyzed carotid ultrasound B-mode cine loops obtained in patients with asymptomatic ≥50% stenosis during routine clinical scanning. Optical flow methods were used to quantify plaque motion and shear strain during the cardiac cycle. The magnitude (maximum absolute shear strain rate [MASSR]) and variability (entropy of shear strain rate [ESSR] and variance of shear strain rate [VSSR]) of strain were combined into a composite shear strain index (SSI), which was assessed for interscan repeatability and correlated with plaque echolucency. Nineteen patients (mean age, 70 years) constituting 36 plaques underwent imaging; 37% of patients (n = 7) showed high strain (SSI ≥0.5; MASSR, 2.2; ESSR, 39.7; VSSR, 0.03) in their plaques; the remaining clustered into a low-strain group (SSI <0.5; MASSR, 0.58; ESSR, 21.2; VSSR, 0.002). The area of echolucent morphology was greater in high-strain plaques vs low-strain plaques (28% vs 17%; P = .018). Strain measurements showed low variability on Bland-Altman plots with cluster assignment agreement of 76% on repeated scanning. Two patients developed a stroke during 2 years of follow-up; both demonstrated high SSI (≥0.5) at baseline. Carotid plaque strain is reliably computed from routine B-mode imaging using clinical ultrasound machines. High plaque strain correlates with known

  19. The many shades of prion strain adaptation.

    Science.gov (United States)

    Baskakov, Ilia V

    2014-01-01

    In several recent studies transmissible prion disease was induced in animals by inoculation with recombinant prion protein amyloid fibrils produced in vitro. Serial transmission of amyloid fibrils gave rise to a new class of prion strains of synthetic origin. Gradual transformation of disease phenotypes and PrP(Sc) properties was observed during serial transmission of synthetic prions, a process that resembled the phenomenon of prion strain adaptation. The current article discusses the remarkable parallels between phenomena of prion strain adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion strain adaptation and synthetic strain evolution are discussed. The current article highlights the complexity of the prion transmission barrier and strain adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.

  20. Vortical and internal wave shear and strain

    OpenAIRE

    Pinkel, R.

    2014-01-01

    Depth-time records of isopycnal vertical strain have been collected from intensive CTD profiling programs on the research platform (R/P) Floating Instrument Platform (FLIP). The associated vertical wavenumber frequency spectrum of strain, when viewed in an isopycnal-following frame, displays a clear spectral gap at low vertical wavenumber, separating the quasigeostrophic (vortical) strain field and the superinertial internal wave continuum. This gap enables both model and linear-filter-based ...

  1. Surface Acoustic Wave Strain Sensor Model

    OpenAIRE

    Wilson, William; Gary ATKINSON

    2011-01-01

    NASA Langley Research Center is investigating Surface Acoustic Wave (SAW) sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC) reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasi...

  2. Immunological Characterization of Pectinatus cerevisiophilus Strains

    OpenAIRE

    Haikara, Auli

    1983-01-01

    Eleven Pectinatus cerevisiophilus strains of brewery origin were classified serologically by gel diffusion precipitin tests, immunoelectrophoresis, and the fluorescent antibody staining technique. The Pectinatus strains could be assigned immunologically to three different groups. Groups I and III were found to be very closely related, and only some of the antisera used showed differences. The antisera against the strains belonging to group II contained a common group antigen. A strong precipi...

  3. Investigation of Electronic Devices for Strain Measurement

    Directory of Open Access Journals (Sweden)

    Ričardas Masiulionis

    2011-08-01

    Full Text Available Importance of strain measuring for safety of buildings is shown. The strain monitoring should be one of the buildings security systems. Often used balanced and non-balanced Wheatstone bridge strain measurement methods are analyzed. The Wheatstone bridge method with feedback is improved. A new method based on small resistance changes by the digital balancing currents is presented. Computer and experimental models of measurement are investigated. The received results confirm theoretical assumptions.Article in Lithuanian

  4. Microminiature temperature-compensated magnetoelastic strain gauge

    Science.gov (United States)

    Arms, Steven W.; Townsend, Christopher P.

    2002-07-01

    Our objective was to demonstrate a microminiature magnetoelastic strain gauge that provides both strain and temperature signals without additional sensors. Iron based magnetoelastic materials were embedded within superelastic nickel/titanium (NiTi) tubing. NiTi stress was transferred to the ferrite, causing a permeability change sensed by a tiny coil. The coil/bridge was excited (70 KHz AC), synchronously demodulated, and amplified to produce a voltage output proportional to coil/ferrite impedance. A DC voltage was also applied and separately conditioned to provide an output proportional to coil resistance; this signal was used to provide thermal compensation. Controlled strains were applied and 6 Hz cyclic outputs recorded simultaneously from the magnetoelastic strain gauge and conventional foil strain gauges. The magnetoelastic strain gauge tracked the foil gauge with minimal hysteresis and good linearity over 600 microstrain; repeatability was approximately 1.5 microstrain. The magnetoelastic strain gauge's gauge factor was computed from delta inductance/original inductance under static strain conditions. Temperatures of 25-140 deg C resulted in an uncompensated shift of 15 microstrain/deg C, and compensated shift of 1.0 microstrain/deg C. A sensitive micro-magnetoelastic strain gauge was demonstrated using the same sensor to detect stress and temperature with no moving parts, high gauge factor, and good thermal stability.

  5. Surface Acoustic Wave Strain Sensor Model

    Directory of Open Access Journals (Sweden)

    William WILSON

    2011-04-01

    Full Text Available NASA Langley Research Center is investigating Surface Acoustic Wave (SAW sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasite substrate. The results of the model of a SAW Strain Sensor on Langasite are presented.

  6. Biochemical properties of highly neuroinvasive prion strains.

    Directory of Open Access Journals (Sweden)

    Cyrus Bett

    2012-02-01

    Full Text Available Infectious prions propagate from peripheral entry sites into the central nervous system (CNS, where they cause progressive neurodegeneration that ultimately leads to death. Yet the pathogenesis of prion disease can vary dramatically depending on the strain, or conformational variant of the aberrantly folded and aggregated protein, PrP(Sc. Although most prion strains invade the CNS, some prion strains cannot gain entry and do not cause clinical signs of disease. The conformational basis for this remarkable variation in the pathogenesis among strains is unclear. Using mouse-adapted prion strains, here we show that highly neuroinvasive prion strains primarily form diffuse aggregates in brain and are noncongophilic, conformationally unstable in denaturing conditions, and lead to rapidly lethal disease. These neuroinvasive strains efficiently generate PrP(Sc over short incubation periods. In contrast, the weakly neuroinvasive prion strains form large fibrillary plaques and are stable, congophilic, and inefficiently generate PrP(Sc over long incubation periods. Overall, these results indicate that the most neuroinvasive prion strains are also the least stable, and support the concept that the efficient replication and unstable nature of the most rapidly converting prions may be a feature linked to their efficient spread into the CNS.

  7. Using strain rates to forecast seismic hazards

    Science.gov (United States)

    Evans, Eileen

    2017-01-01

    One essential component in forecasting seismic hazards is observing the gradual accumulation of tectonic strain accumulation along faults before this strain is suddenly released as earthquakes. Typically, seismic hazard models are based on geologic estimates of slip rates along faults and historical records of seismic activity, neither of which records actively accumulating strain. But this strain can be estimated by geodesy: the precise measurement of tiny position changes of Earth’s surface, obtained from GPS, interferometric synthetic aperture radar (InSAR), or a variety of other instruments.

  8. Material approaches to stretchable strain sensors.

    Science.gov (United States)

    Park, Jaeyoon; You, Insang; Shin, Sangbaie; Jeong, Unyong

    2015-04-27

    With the recent progress made in wearable electronics, devices now require high flexibility and stretchability up to large strain levels (typically larger than 30 % strain). Wearable strain sensors or deformable strain sensors have been gaining increasing research interest because of the rapid development of electronic skins and robotics and because of their biomedical applications. Conventional brittle strain sensors made of metals and piezoresistors are not applicable for such stretchable sensors. This Review summarizes recent advances in stretchable sensors and focuses on material aspects for high stretchability and sensitivity. It begins with a brief introduction to the Wheatstone bridge circuit of conventional resistive strain sensors. Then, studies on the manipulation of materials are reviewed, including waved structural approaches for making metals and semiconductors stretchable, the use of liquid metals, and conductive filler/elastomer composites by using percolation among the fillers. For capacitive strain sensors, the constant conductivity of the electrode is a key factor in obtaining reliable sensors. Possible approaches to developing capacitive strain sensors are presented. This Review concludes with a discussion on the major challenges and perspectives related to stretchable strain sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. True stress–strain curves of cold worked stainless steel over a large range of strains

    Energy Technology Data Exchange (ETDEWEB)

    Kamaya, Masayuki, E-mail: kamaya@inss.co.jp; Kawakubo, Masahiro

    2014-08-01

    True stress–strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress–strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress–strain curves. The stress–strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress–strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress–strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg–Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be n{sub S} = 0.5.

  10. True stress-strain curves of cold worked stainless steel over a large range of strains

    Science.gov (United States)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

    True stress-strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress-strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress-strain curves. The stress-strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress-strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress-strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg-Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5.

  11. Rotavirus strains circulating in Africa during 1996-1999: emergence of G9 strains and P[6] strains.

    Science.gov (United States)

    Steele, A D; Ivanoff, B

    2003-01-17

    Rotavirus infection is associated with 150000-200000 deaths annually in Africa. Although the withdrawal of the RotaShield vaccine has been a major setback in rotavirus vaccine development, new vaccine candidates are under development and approaching phase II and III trials. Before these trials could be conducted in Africa, a comprehensive survey of the circulating VP7 serotypes and VP4 genotypes is required. During the past 3 years, over 3000 rotavirus-positive specimens from several African countries have been analysed. RT-PCR techniques for the VP7 and VP4 genotypes and by monoclonal antibodies to the VP6 subgroup and VP7 serotype have been performed. Almost 75% of the strains were typed by the VP7 monoclonal antibodies or RT-PCR. VP4 genotyping was done in approximately half of these strains. The predominant strains circulating across Africa during 1996-1999 were P[6]G1 and P[6]G3 strains. Geographic differences were noted and West Africa displayed the most diverse strains with G3/8 and G1/3 "mosaic" viruses occurring commonly. G9 strains were identified in several countries indicating that the strain is emerging in Africa too. G9 was the predominant strain in certain countries during 1999. The circulating types observed will have implications for the new rotavirus vaccine candidates.

  12. Enzymes From Rare Actinobacterial Strains.

    Science.gov (United States)

    Suriya, J; Bharathiraja, S; Manivasagan, P; Kim, S-K

    Actinobacteria constitute rich sources of novel biocatalysts and novel natural products for medical and industrial utilization. Although actinobacteria are potential source of economically important enzymes, the isolation and culturing are somewhat tough because of its extreme habitats. But now-a-days, the rate of discovery of novel compounds producing actinomycetes from soil, freshwater, and marine ecosystem has increased much through the developed culturing and genetic engineering techniques. Actinobacteria are well-known source of their bioactive compounds and they are the promising source of broad range of industrially important enzymes. The bacteria have the capability to degrade a range of pesticides, hydrocarbons, aromatic, and aliphatic compounds (Sambasiva Rao, Tripathy, Mahalaxmi, & Prakasham, 2012). Most of the enzymes are mainly derived from microorganisms because of their easy of growth, minimal nutritional requirements, and low-cost for downstream processing. The focus of this review is about the new, commercially useful enzymes from rare actinobacterial strains. Industrial requirements are now fulfilled by the novel actinobacterial enzymes which assist the effective production. Oxidative enzymes, lignocellulolytic enzymes, extremozymes, and clinically useful enzymes are often utilized in many industrial processes because of their ability to catalyze numerous reactions. Novel, extremophilic, oxidative, lignocellulolytic, and industrially important enzymes from rare Actinobacterial population are discussed in this chapter. © 2016 Elsevier Inc. All rights reserved.

  13. High-strain, high-strain-rate deformation of tantalum and tantalum-tungsten alloys

    OpenAIRE

    Vecchio, K.

    1994-01-01

    Under certain high strain rate conditions, plastic deformation can be assumed to be adiabatic, and a significant temperature increase can occur at large strains. In this study, tantalum and tantalum-tungsten alloys were subjected to high shear strains at high strain rate using a specially-designed stepped specimen in a Hopkinson bar. Upon completion of the deformation, the region is cooled to below one-half of the temperature achieved due to the adiabatic heating in less than one millisecond....

  14. Petroleum-hydrocarbons biodegradation by Pseudomonas strains ...

    African Journals Online (AJOL)

    Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. In this study, two bacterial strains were isolated from a contaminated soil of a refinery of Arzew (Oran). The isolated strains were identified as Pseudomonas aeruginosa (P3) and Pseudomonas fluoresens (P4).

  15. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, Tina Kold; Bonde, J P

    1998-01-01

    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  16. Active strain modulation in field effect devices

    NARCIS (Netherlands)

    van Hemert, T.; Hueting, Raymond Josephus Engelbart

    2012-01-01

    In this work we propose a novel feature for the transistor: a piezo-electric layer for strain modulation of the channel. The strain is formed at strong inversion only, to obtain a lower threshold voltage, but will be absent in the off-state to preserve the unstrained leakage current. Our results,

  17. Unpolished Thai Rice Strain of Leum Phua

    African Journals Online (AJOL)

    Erah

    Additionally, phenolic content and anthocyanin pigment were also assayed. Results: Oryza sativa, unpolished Thai rice strain of Leum Phua showed the highest antioxidant activity. It was also highest in anthocyanin pigment. The strains of Leum Phua, Klam, Hawm Nil and Black Rose showed high levels of phenolic content: ...

  18. Strain differentiation of polioviruses with monoclonal antibodies.

    NARCIS (Netherlands)

    A.D.M.E. Osterhaus (Albert); A.L. van Wezel; A.J.H. Stegmann; J.A.A.M. van Asten (Jack)

    1984-01-01

    textabstractPanels of monoclonal antibodies raised against different poliovirus type 1, 2 and 3 strains, were tested in a micro-neutralization test and in a micro-enzyme linked immunosorbent assay against a large number of poliovirus strains. The results were compared with those obtained with the

  19. Strain mapping analysis of textile composites

    NARCIS (Netherlands)

    Ivanov, Dimitry; Ivanov, S.; Lomov, Stepan; Verpoest, Ignaas

    2009-01-01

    The focus of the work is meso-scale analysis (scale level of the fabric unit cell) of textile composite deformation and failure. The surface strain measurement is used for: (1) experimental investigation, which includes study of strain distribution at various stages of deformation, plasticity

  20. Organic metabolites produced by Vibrio parahaemolyticus strain ...

    African Journals Online (AJOL)

    Identification and action of several antibacterial metabolites produced by a fish pathogen Vibrio parahaemolyticus strain An3 from marine ecosystem of Goa has been demonstrated. Antibacterial activity of the crude cell extract of the test bacterium has been evaluated against indicator pathogenic bacterial strains such as ...

  1. Medically Complex Home Care and Caregiver Strain

    Science.gov (United States)

    Moorman, Sara M.; Macdonald, Cameron

    2013-01-01

    Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' strain and (b) whether the level of complexity of nursing tasks contributes to variation in strain among caregivers providing help with such tasks. Design and methods: The data came from the Cash…

  2. Broken Bones, Sprains, and Strains (For Parents)

    Science.gov (United States)

    ... a muscle or tendon is overstretched or torn. Sprains and strains generally cause swelling and pain, and there may be bruises ... you can, lift the legs. For a Suspected Sprain or Strain: If the ... Movement can cause serious nerve damage. Phone for emergency medical help. ...

  3. drug resistant strains of Salmonella enterica

    African Journals Online (AJOL)

    Background : The emergence of strains of S.enterica with multiple drug resistance (MDR) is of great concern worldwide.The extracts of flowers of Thonningia sanguinea are used in traditional medicine in Ivory Coast to treat diarrhoeal diseases including salmonellosis. Previous studies had shown inhibition of the MDR strain ...

  4. Preliminary characterization of slow growing rhizobial strains ...

    African Journals Online (AJOL)

    In this paper, we did some preliminary characterization of six slow growing rhizobial strains, isolated from Retama monosperma (L.) Boiss. root nodules sampled from 3 sites along the coast of Oran (CapeFalcon, Bousfer and MersElHadjadj) in Northwestern Algeria. Results of this study showed that all strains had a very ...

  5. Nanocomposite Strain Gauges Having Small TCRs

    Science.gov (United States)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  6. Strain engineering in graphene by laser irradiation

    Science.gov (United States)

    Papasimakis, N.; Mailis, S.; Huang, C. C.; Al-Saab, F.; Hewak, D. W.; Luo, Z.; Shen, Z. X.

    2015-02-01

    We demonstrate that the Raman spectrum of graphene on lithium niobate can be controlled locally by continuous exposure to laser irradiation. We interpret our results in terms of changes to doping and mechanical strain and show that our observations are consistent with light-induced gradual strain relaxation in the graphene layer.

  7. Strain histograms are equal to strain ratios in predicting malignancy in breast tumours

    DEFF Research Database (Denmark)

    Carlsen, Jonathan Frederik; Ewertsen, Caroline; Sletting, Susanne

    2017-01-01

    could be upgraded for immediate biopsy. Linear regression was performed to evaluate the effect of tumour depth and size, and breast density on strain elastography. Results: Forty-four of 99 (44.4%) tumours were malignant. AUROC of BI-RADS, strain histograms and strain ratios were 0.949, 0.830 and 0...

  8. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    Science.gov (United States)

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  9. Strain rate effects in stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

    1990-03-01

    Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

  10. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka

    2016-01-01

    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  11. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjøllund, Niels Henrik Ingvar; Jensen, T.K.; Bonde, J.P.

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... time periods are the relevant measure. We followed a cohort of first pregnancy planners from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses include 181 pregnancies, of which 32 were subclinical pregnancies detected by hCG analysis only. During early...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  12. Atlas of stress-strain curves

    CERN Document Server

    2002-01-01

    The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...

  13. Strain in Archean Granite-Greenstone terrains

    Science.gov (United States)

    Robin, C. M.; Bailey, R. C.

    2009-12-01

    A long-standing problem in Archean tectonics is the mode of origin of granite-greenstone belts. Based on structural and morphological similarities to salt domes and Rayleigh-Taylor structures, diapirism has long been an obvious but controversial candidate, as it implies the operation of vertical tectonics in the Archean. Current strain patterns are one of the few field observables available to test hypotheses about the kinematic history of granite-greenstone belts. Previous laboratory (Dixon & Summers, 1983) and numerical (Mareschal & West, 1980) experiments which have been used to predict strain in diapiric structures may not be realistic because of the lack of large thermally activated viscosity contrasts in these models. We have numerically modeled temperature-dependent, non-Newtonian visco-elastic solid-state diapirism under conditions appropriate to Archean crust (Robin & Bailey, 2009). Here we present analyses of strain derived from these models. Our results show important differences from those of previous modelers. These include the formation of narrow high strain zones in the greenstone at the batholith contact and in the axis of the keel, with a low-strain zone between the two, as well as only very small strains in the batholith itself. This suggests that strain recorded in the granitic domes of granite-greenstone terrains must be unrelated to the diapiric overturn mechanism. Our strain analyses should be useful for comparison with published and future field observations, and provide a basis for the interpretation of strain in these ubiquitous Archean structures. Principle strain directions for an evolved diapir resulting from an altered basaltic crust deposited over a granitic basement. Viscosities are temperature- and stress-dependent and viscoelastic.

  14. Strain specificity and simultaneous transmission of closely related strains of a Potyvirus by Myzus persicae.

    Science.gov (United States)

    Srinivasan, Rajagopalbabu; Hall, Darren G; Cervantes, Felix A; Alvarez, Juan M; Whitworth, Jonathan L

    2012-06-01

    Potato virus Y (PVY), a Potyvirus, is transmitted by aphids in a nonpersistent manner. PVY severely affects potato production worldwide. Single and mixed infections of PVY strains, namely PVY(O), PVY(NTN), and PVY(N:O) are a common occurrence in potato systems. However, information available on the ability of aphids to simultaneously transmit multiple PVY strains, specificity associated with simultaneous transmission, and factors affecting specificity are limited. Aphid-mediated transmission experiments were conducted to test the ability of individual aphids to transmit multiple strains using a PVY indicator host. Preliminary results revealed that aphids can transmit at least two viral strains simultaneously. Subsequently, aphid-mediated transmission of three dual-strain combinations was tested using potato plants. Individual aphids transmitted two viral strains simultaneously for all three dual-strain combinations. In all aphid-mediated dual-strain infections involving PVY(NTN), the rate of PVY(NTN) infection was greater than the infection rates of the second strain and dual-strain combinations, indicating specificity associated with transmission of PVY strains. Results of aphid-mediated transmission experiments were compared with results obtained through mechanical transmission. In general, PVY infection rates from aphid-mediated transmission were lower than the rates obtained through mechanical transmission. Unlike aphid-mediated transmission, component strains in dual-strain inoculations were not eliminated during mechanical transmission. These results suggest that there may also be interference associated with aphid-mediated transmission of closely related PVY strains. Perhaps, the observed specificity and/or interference may explain the increase in the incidence of PVY(NTN) and other necrotic strains in recent years.

  15. Strain relaxation in nano-patterned strained-Si/SiGe heterostructure on insulator

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xuyn, E-mail: liuyan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Graduate University of Chinese Academy of Sciences, Beijing 100080 (China); Liu Weili, E-mail: rabbitlwl@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Ma Xiaobo [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China); Graduate University of Chinese Academy of Sciences, Beijing 100080 (China); Lv Shilong; Song Zhitang; Lin Chenglu [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)

    2010-03-15

    In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by Electron-Beam Lithography (EBL) and Reactive-Ion Etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of <15% is observed in pillars with a dimension of 150 nm x 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.

  16. Chemical Profile of Monascus ruber Strains

    Directory of Open Access Journals (Sweden)

    Ahamed M. Moharram

    2012-01-01

    Full Text Available Chemical profile of Monascus ruber strains has been studied using gas chromatography-mass spectrometry (GC/MS analysis. The colour intensity of the red pigment and secondary metabolic products of two M. ruber strains (AUMC 4066 and AUMC 5705 cultivated on ten different media were also studied. Metabolic products can be classified into four categories: anticholesterol, anticancer, food colouring, and essential fatty acids necessary for human health. Using GC/MS, the following 88 metabolic products were detected: butyric acid and its derivatives (25 products, other fatty acids and their derivatives (19 products, pyran and its derivatives (22 products and other metabolites (22 products. Among these, 32 metabolites were specific for AUMC 4066 strain and 34 for AUMC 5705 strain, whereas 22 metabolites were produced by both strains on different tested substrates. Production of some metabolites depended on the substrate used. High number of metabolites was recorded in the red pigment extract obtained by both strains grown on malt broth and malt agar. Also, 42 aroma compounds were recorded (4 alcohols, 2 benzaldehydes, 27 esters, 3 lactones, 1 phenol, 1 terpenoid, 3 thiol compounds and acetate-3-mercapto butyric acid. Thin layer chromatography and GC/MS analyses revealed no mycotoxin citrinin in any media used for the growth of the two M. ruber strains.

  17. Measuring strength at ultrahigh strain rates.

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Tracy John

    2010-03-01

    The strain rate sensitivity of materials is measured through a combination of quasistatic, Hopkinson bar, and pressure-shear experiments. The pressure-shear technique has largely been limited to strain rates of order 1E6 1/s. Recent advances in laser and magnetically driven ramp loading have made it possible to achieve significantly higher rates, 1E5-1E8 1/s, under uniaxial strain compression. Strength in these experiments can be calculated by comparing the loading response to the hydrostatic (pressure-density) response of the material for the same density and temperature [Fowles, 1961]. This must be done accounting for the heating due to plastic work in the experiments. Experimental uniaxial strain data for aluminum for strain rates up to 1E8 1/s are examined and compared with existing data. The results are consistent with conventional views of the strain rate sensitivity of aluminum. However, when one considers the higher mean stress (pressure) present in the uniaxial strain experiments and, to a lesser extent, the pressure-shear experiments, one finds the material remains rate insensitive to about 1E7 1/s, two orders of magnitude higher than previously thought. Important caveats about determining strength in this manner will be discussed, and recommendations for future work will be made.

  18. [Screening and optimization of cholesterol conversion strain].

    Science.gov (United States)

    Fan, Dan; Xiong, Bingjian; Pang, Cuiping; Zhu, Xiangdong

    2014-10-04

    Bacterial strain SE-1 capable of transforming cholesterol was isolated from soil and characterized. The transformation products were identified. Fermentation conditions were optimized for conversion. Cholesterol was used as sole carbon source to isolate strain SE-1. Morphology, physiological and biochemical characteristics of strain SE-1 were studied. 16S rRNA gene was sequenced and subjected to phylogenetic analysis. Fermentation supernatants were extracted with chloroform, the transformation products were analyzed by silica gel thin layer chromatography and Sephadex LH20. Their structures were identified by 1H-NMR and 13C-NMR. Fermentation medium including carbon and nitrogen, methods of adding substrates and fermentation conditions for Strain SE-1 were optimized. Strain SE-1 was a Gram-negative bacterium, exhibiting the highest homologs to Burkholderia cepacia based on the physiological analysis. The sequence analysis of 16S rRNA gene of SE-1 strain and comparison with related Burkholderia show that SE-1 strain was very close to B. cepacia (Genbank No. U96927). The similarity was 99%. The result of silica gel thin layer chromatography shows that strain SE-1 transformed cholesterol to two products, 7beta-hydroxycholesterol and the minor product was 7-oxocholesterol. The optimum culture conditions were: molasses 5%, (NH4 )2SO4 0.3%, 4% of inoculation, pH 7.5 and 36 degrees C. Under the optimum culture condition, the conversion rate reached 34.4% when concentration of cholesterol-Tween 80 was 1 g/L. Cholesterol 7beta-hydroxylation conversion rate under optimal conditions was improved by 20.8%. Strain SE-1 isolated from soil is capable of converting cholesterol at lab-scale.

  19. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-09-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  20. Biological characterization of Trypanosoma cruzi strains

    Directory of Open Access Journals (Sweden)

    Martínez-Díaz Rafael A

    2001-01-01

    Full Text Available Biological parameters of five Trypanosoma cruzi strains from different sources were determined in order to know the laboratory behaviour of natural populations. The parameters evaluated were growth kinetics of epimastigotes, differentiation into metacyclic forms, infectivity in mammalian cells grown in vitro and parasite susceptibility to nifurtimox, benznidazole and gentian violet. Differences in transformation to metacyclic, in the percentage of infected cells as well as in the number of amastigotes per cell were observed among the strains. Regarding to pharmacological assays, Y strain was the most sensitive to the three assayed compounds. These data demonstrate the heterogeneity of natural populations of T. cruzi, the only responsible of infection in humans.

  1. ANTIBIOTIC SUSCEPTIBILITY OF POTENTIALLY PROBIOTIC LACTOBACILLUS STRAINS

    Directory of Open Access Journals (Sweden)

    Junhua Han

    2015-09-01

    Full Text Available Susceptibility of 29 Lactobacilli to 13 antibiotics was assayed by paper disc diffusion method. Plasmids and gastrointestinal tolerance were detected. The relationship between plasmids andantibiotic resistance was discussed. The results showed that all of the strains were resistant to bacitracin, polymyxin B, kanamycin, and nalidixic acid. Many strains were relatively sensitive tochloramphenicol and tetracycline. Six strains contained plasmids and showed good gastrointestinal tolerance. β-lactam resistance gene blr was found in the plasmid of L. plantarum CICC 23180by PCR. The study will be helpful to promote the safety evaluation and development of potentially probiotic lactic acid bacteria.

  2. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the t...... the tangential moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that appears to be unphysical....

  3. Immunological Characterization of Pectinatus cerevisiophilus Strains.

    Science.gov (United States)

    Haikara, A

    1983-11-01

    Eleven Pectinatus cerevisiophilus strains of brewery origin were classified serologically by gel diffusion precipitin tests, immunoelectrophoresis, and the fluorescent antibody staining technique. The Pectinatus strains could be assigned immunologically to three different groups. Groups I and III were found to be very closely related, and only some of the antisera used showed differences. The antisera against the strains belonging to group II contained a common group antigen. A strong precipitation band found near the antigen was shown to represent the interaction of the lipopolysaccharide antibody and the respective antigen.

  4. Fractional Josephson effect in nonuniformly strained graphene

    Science.gov (United States)

    Lee, Shu-Ping; Nandi, Debaleena; Marsiglio, Frank; Maciejko, Joseph

    2017-05-01

    Nonuniform strain distributions in a graphene lattice can give rise to uniform pseudomagnetic fields and associated pseudo-Landau levels without breaking time-reversal symmetry. We demonstrate that by inducing superconductivity in a nonuniformly strained graphene sheet, the lowest pseudo-Landau levels split by a pairing gap can be inverted by changing the sign of the pairing potential. As a consequence of this inversion, we predict that a Josephson π junction deposited on top of a strained graphene sheet exhibits one-dimensional gapless modes propagating along the junction. These gapless modes mediate single electron tunneling across the junction, giving rise to the 4 π -periodic fractional Josephson effect.

  5. Serologic differences in strains of Sporothrix schenckii.

    Science.gov (United States)

    Nishikawa, T; Harada, T; Harada, S; Hatano, H

    1975-11-01

    To obtain evidence that Sporothrix scheneckii enters the body by contact with contaminated materials, the antigenic property of strains from different sources was investigated. The reciprocal absorption test of the antisera against a soil isolate and a human isolate (KO 4606) showed that the absorbed antisera against KO 4606 possessed unique antigen(s) in addition to the common antigen of both strains. Twenty-three clinical isolates were tested with absorbed antisera. Not all of them possessed the unique antigen(s), but there were serologic varieties among S. schenckii strains, regardless of their sources, clinical type of the disease and the morphology of the yeast phase cells.

  6. Rat Strain Ontology: structured controlled vocabulary designed to facilitate access to strain data at RGD.

    Science.gov (United States)

    Nigam, Rajni; Munzenmaier, Diane H; Worthey, Elizabeth A; Dwinell, Melinda R; Shimoyama, Mary; Jacob, Howard J

    2013-11-22

    The Rat Genome Database (RGD) ( http://rgd.mcw.edu/) is the premier site for comprehensive data on the different strains of the laboratory rat (Rattus norvegicus). The strain data are collected from various publications, direct submissions from individual researchers, and rat providers worldwide. Rat strain, substrain designation and nomenclature follow the Guidelines for Nomenclature of Mouse and Rat Strains, instituted by the International Committee on Standardized Genetic Nomenclature for Mice. While symbols and names aid in identifying strains correctly, the flat nature of this information prohibits easy search and retrieval, as well as other data mining functions. In order to improve these functionalities, particularly in ontology-based tools, the Rat Strain Ontology (RS) was developed. The Rat Strain Ontology (RS) reflects the breeding history, parental background, and genetic manipulation of rat strains. This controlled vocabulary organizes strains by type: inbred, outbred, chromosome altered, congenic, mutant and so on. In addition, under the chromosome altered category, strains are organized by chromosome, and further by type of manipulations, such as mutant or congenic. This allows users to easily retrieve strains of interest with modifications in specific genomic regions. The ontology was developed using the Open Biological and Biomedical Ontology (OBO) file format, and is organized on the Directed Acyclic Graph (DAG) structure. Rat Strain Ontology IDs are included as part of the strain report (RS: ######). As rat researchers are often unaware of the number of substrains or altered strains within a breeding line, this vocabulary now provides an easy way to retrieve all substrains and accompanying information. Its usefulness is particularly evident in tools such as the PhenoMiner at RGD, where users can now easily retrieve phenotype measurement data for related strains, strains with similar backgrounds or those with similar introgressed regions. This

  7. Effect of strain and strain rate on fatigue-accelerated biodegradation of polyurethane.

    Science.gov (United States)

    Wiggins, Michael J; Anderson, James M; Hiltner, Anne

    2003-09-01

    A diaphragm-type film specimen was used to study in vitro degradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading. This geometry allowed both uniaxial and biaxial loading in a single experiment. During testing, the film was exposed to a H(2)O(2)/CoCl(2) solution that simulated in vivo oxidation of PEUU. The combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation. The effects of biaxial strain magnitude and strain rate were examined separately by increasing the frequency of fatigue loading from 0 to 1 Hz with constant maximum biaxial strain and by changing the maximum biaxial strain while maintaining constant strain rate. In the ranges of biaxial strain energy (0.17 to 0.55 MPa) and strain rate (0 to 46% s(-1)) tested, the rate of degradation increased with increasing strain rate whereas strain magnitude had essentially no effect on degradation rate. Although loading conditions affected the rate of oxidative degradation, ATR-FTIR analysis suggested that in all cases the mechanism of degradation did not change. Chemical degradation produced a brittle crosslinked surface layer marked by dimpling and pitting, as observed with scanning electron microscopy. Pits served as stress concentrators and initiated environmental stress cracks under dynamic loading but not under static (creep) loading. Small pits were sufficient to initiate cracks at higher strain rates whereas only large pits initiated cracks at lower strain rates. Consequently, a higher strain rate produced more profuse cracking. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 463-475, 2003

  8. Energy Harvesting Wireless Strain Networks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Prime Research LC (PPLC) and Virginia Tech (VT) propose to develop an energy harvesting wireless strain node technology that utilizes single-crystal piezoelectric...

  9. Characterization of 3 Strains of Yersinia Pestis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    .... Antibiotic sensitivities showed that the 3 strains were sensitive to aminoglycosides, the cephalosporins/ cephams, most of the beta lactams/penicillins (e.g. ampicillin) and quinolones (e.g. ciprofloxacin...

  10. Characterization of 21 Strains of Bacillus Anthracis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    Twenty-one strains of Bacillus anthracis currently held in the culture collection at DRES were characterized by colonial morphology, antibiotic sensitivity and BiologTM metabolic identification profiles...

  11. Gap discrete breathers in strained boron nitride

    Science.gov (United States)

    Barani, Elham; Korznikova, Elena A.; Chetverikov, Alexander P.; Zhou, Kun; Dmitriev, Sergey V.

    2017-11-01

    Linear and nonlinear dynamics of hexagonal boron nitride (h-BN) lattice is studied by means of molecular dynamics simulations with the use of the Tersoff interatomic potentials. It is found that sufficiently large homogeneous elastic strain along zigzag direction opens a wide gap in the phonon spectrum. Extended vibrational mode with boron and nitrogen sublattices vibrating in-plane as a whole in strained h-BN has frequency within the phonon gap. This fact suggests that a nonlinear spatially localized vibrational mode with frequencies in the phonon gap, called discrete breather (also often termed as intrinsic localized mode), can be excited. Properties of the gap discrete breathers in strained h-BN are contrasted with that for analogous vibrational mode found earlier in strained graphene. It is found that h-BN modeled with the Tersoff potentials does not support transverse discrete breathers.

  12. Optical physics: Magnetic appeal in strained lattice

    Science.gov (United States)

    Lepetit, Thomas

    2013-02-01

    Using strain to induce a pseudomagnetic field in a photonic lattice at optical frequencies might bring improvements to fields such as photonic crystal fibres, supercontinuum generation and frequency combs.

  13. Job strain and the risk of stroke

    DEFF Research Database (Denmark)

    Fransson, Eleonor I; Nyberg, Solja T; Heikkilä, Katriina

    2015-01-01

    BACKGROUND AND PURPOSE: Psychosocial stress at work has been proposed to be a risk factor for cardiovascular disease. However, its role as a risk factor for stroke is uncertain. METHODS: We conducted an individual-participant-data meta-analysis of 196 380 males and females from 14 European cohort...... studies to investigate the association between job strain, a measure of work-related stress, and incident stroke. RESULTS: In 1.8 million person-years at risk (mean follow-up 9.2 years), 2023 first-time stroke events were recorded. The age- and sex-adjusted hazard ratio for job strain relative to no job....... CONCLUSION: Job strain may be associated with an increased risk of ischemic stroke, but further research is needed to determine whether interventions targeting job strain would reduce stroke risk beyond existing preventive strategies....

  14. Anterior Cruciate Ligament Strain In Vivo

    Science.gov (United States)

    Luque-Seron, Juan Antonio; Medina-Porqueres, Ivan

    2016-01-01

    Context: Distinct exercises have been proposed for knee rehabilitation after anterior cruciate ligament (ACL) reconstruction. There is a need to understand ACL strain behavior during different rehabilitation exercises to protect the graft from excessive strain that could interfere with its healing process. Objective: To critically review studies that directly measured normal ACL strain in vivo during different movements, conditions, or exercises to gain insight into which of them may produce more strain on the ligament or the ligament graft in the case of reconstructed knees. Data Sources: A literature search of PubMed, CINAHL, SPORTDiscus, and PEDro databases was conducted. Keywords included anterior cruciate ligament, strain, stress, deformation, transducer, rehabilitation, rehabilitation exercise, physical therapy, and physiotherapy. Study Selection: Inclusion criteria were (1) peer-reviewed studies published in English or Spanish, (2) research conducted on adult human subjects with normal ACLs and healthy knees, and (3) ACL strain directly measured during different movements, conditions, or exercises by using a transducer. Study Design: Systematic review. Level of Evidence: Level 4. Data Extraction: Specific data were abstracted from the selected studies, including isometric quadriceps and hamstrings activity, active and passive flexion-extension of the knee, closed kinetic chain exercises, and application of joint compressive load. Results: A total of 10 studies met all criteria and were included in the final analysis. The strain values produced by closed kinetic chain and open kinetic chain exercises were similar. However, closed kinetic chain exercises appear to attenuate the strain increase that occurs in open kinetic chain exercises when increasing resistance. Conclusion: These data may be relevant to develop rehabilitation exercises or programs that do not endanger the healing ACL graft and to provide a basis for future clinical trials. PMID:27418161

  15. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  16. A closer look at prion strains

    Science.gov (United States)

    Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

    2013-01-01

    Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

  17. Differentiation of Mycoplasma gallisepticum Strains through RFLP

    Directory of Open Access Journals (Sweden)

    Luis José Carrión

    2012-12-01

    Full Text Available Avian mycoplasmosis is a disease that considerably affects the poultry sector, which is reflected in the decrease of the production parameters in fertile and commercial egg laying broilers. Presentation costs are so high that it is impossible for the poultry industry to survive without thinking of its effective control or eradication. There is great interest in the type of M. gallisepticum (Mg strains, both vaccine and field, which are key aspects to handle the disease, but there is still no definitive method for Mg strain characterization. Genes related to surface proteins —gapA and mgc2,lipoprotein (lp— that make it possible to identify and characterize the Mg genomically are currently being studied. In this study, regions of the lp gene were amplified from strains F and Ts-11 of Mg through the polymerase chain reaction (PCR technique, which gave an amplicon of 455 bp for each of the strains; each of the amplicons was applied the restriction fragment length polymorphism (RFLP test with the Taq I enzyme, which made it possible to differentiate vaccine strains from field strains obtained from tracheal swab samples taken at commercial farms. It was demonstrated that PCRRFLP is an appropriate method of diagnosis of mycoplasmosis in our environment.

  18. Polymerization shrinkage strain of interocclusal recording materials.

    Science.gov (United States)

    Chun, Jung-hyun; Pae, Ahran; Kim, Sung-hun

    2009-01-01

    The aim of this in vitro study was to investigate the polymerization shrinkage behavior and to measure the polymerization shrinkage-strain of interocclusal recording materials. The materials investigated in this study were five polyvinylsiloxane (Imprint Bite, Silagum Automix Bite, O-Bite, Blu-Mousse Classic and Exabite II), one polyether (Ramitec) and one dimethacrylatebased (Luxabite) materials. The polymerization shrinkage values of ten specimens for each material were measured by the Bonded-disk method at 1, 3, 5, 7 and 10 min after mixing at 37 degrees C. The amount of shrinkage-strain (%) was derived and all data were statistically analyzed by one-way ANOVA and the multiple comparison Scheffé test (alpha=0.05). The representative shrinkage-strain kinetic graphs showed that all specimens shrank immediately, except Luxabite which expanded for the initial few seconds. After that, the shrinkage-strain values increased in the magnitude up to 10 min, but its rate decreased gradually with time. The shrinkage-strain values (0.18+/-0.03-0.16+/-0.03%) of O-Bite at 5, 7 and 10 min were significantly lower than the other materials, but Luxabite exhibited the highest values (3.10+/-0.17-3.30+/-0.16%). The interocclusal recording materials investigated presented significantly different polymerization shrinkage-strain kinetics and showed dimensional changes even after the setting time indicated by respective manufacturers.

  19. Skeletal muscle tensile strain dependence: hyperviscoelastic nonlinearity

    Science.gov (United States)

    Wheatley, Benjamin B; Morrow, Duane A; Odegard, Gregory M; Kaufman, Kenton R; Donahue, Tammy L Haut

    2015-01-01

    Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of strain. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% strain. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for strain dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the strain dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are strain-dependent at the tissue level. This strain dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model. PMID:26409235

  20. Strain-controlled electrocatalysis on multimetallic nanomaterials

    Science.gov (United States)

    Luo, Mingchuan; Guo, Shaojun

    2017-11-01

    Electrocatalysis is crucial for the development of clean and renewable energy technologies, which may reduce our reliance on fossil fuels. Multimetallic nanomaterials serve as state-of-the-art electrocatalysts as a consequence of their unique physico-chemical properties. One method of enhancing the electrocatalytic performance of multimetallic nanomaterials is to tune or control the surface strain of the nanomaterials, and tremendous progress has been made in this area in the past decade. In this Review, we summarize advances in the introduction, tuning and quantification of strain in multimetallic nanocrystals to achieve more efficient energy conversion by electrocatalysis. First, we introduce the concept of strain and its correlation with other key physico-chemical properties. Then, using the electrocatalytic reduction of oxygen as a model reaction, we discuss the underlying mechanisms behind the strain-adsorption-reactivity relationship based on combined classical theories and models. We describe how this knowledge can be harnessed to design multimetallic nanocrystals with optimized strain to increase the efficiency of oxygen reduction. In particular, we highlight the unexpectedly beneficial (and previously overlooked) role of tensile strain from multimetallic nanocrystals in improving electrocatalysis. We conclude by outlining the challenges and offering our perspectives on the research directions in this burgeoning field.

  1. Elastically Relaxed Free-standing Strained-Si Nanomembranes

    OpenAIRE

    Roberts, Michelle M.; Klein, Levente J.; Savage, Don E.; Slinker, Keith A.; Friesen, Mark; Celler, George; Eriksson, Mark A.; Lagally, Max G.

    2006-01-01

    Strain plays a critical role in the properties of materials. In silicon and silicon-germanium, strain provides a mechanism for control of both carrier mobility and band offsets. In materials integra-tion, strain is typically tuned through the use of dislocations and elemental composition. We demonstrate a versatile method to control strain, by fabricating membranes in which the final strain state is controlled by elastic strain sharing, i.e., without the formation of defects. We grow Si/SiGe ...

  2. Purification of Helicobacter suis Strains From Biphasic Cultures by Single Colony Isolation: Influence on Strain Characteristics.

    Science.gov (United States)

    Liang, Jungang; De Bruyne, Ellen; Ducatelle, Richard; Smet, Annemieke; Haesebrouck, Freddy; Flahou, Bram

    2015-06-01

    Helicobacter (H.) suis causes gastritis and decreased weight gain in pigs. It is also the most prevalent non-Helicobacter pylori Helicobacter species in humans with gastric disease. H. suis is extremely fastidious, and so far, biphasic culture conditions were essential for isolation and culture, making it impossible to obtain single colonies. Hence, cultures obtained from an individual animal may contain multiple H. suis strains, which is undesirable for experiments aiming for instance at investigating H. suis strain differences. Pure cultures of H. suis were established by growing bacteria as colonies on 1% brucella agar plates, followed by purification and enrichment by biphasic subculture. Characteristics of these single colony-derived strains were compared with those of their parent strains using multilocus sequence typing (MLST) and by studying bacterium-host interactions using a gastric epithelial cell line and Mongolian gerbil model. The purification/enrichment procedure required a nonstop culture of several weeks. For 4 of 17 H. suis strains, MLST revealed differences between parental and single colony-derived strains. For three of four single colony-derived strains tested, the cell death-inducing capacity was higher than for the parental strain. One single colony-derived strain lost its capacity to colonize Mongolian gerbils. For the four other strains tested, colonization capacity and histopathologic changes were similar to what has been described when using strains with only a history of limited biphasic culture. A method was developed to obtain single colony-derived H. suis strains, but this procedure may affect the bacterial genotype and phenotype. © 2015 John Wiley & Sons Ltd.

  3. Intramyocardial strain estimation from cardiac cine MRI.

    Science.gov (United States)

    Elnakib, Ahmed; Beache, Garth M; Gimel'farb, Georgy; El-Baz, Ayman

    2015-08-01

    Functional strain is one of the important clinical indicators for the quantification of heart performance and the early detection of cardiovascular diseases, and functional strain parameters are used to aid therapeutic decisions and follow-up evaluations after cardiac surgery. A comprehensive framework for deriving functional strain parameters at the endocardium, epicardium, and mid-wall of the left ventricle (LV) from conventional cine MRI data was developed and tested. Cine data were collected using short TR-/TE-balanced steady-state free precession acquisitions on a 1.5T Siemens Espree scanner. The LV wall borders are segmented using a level set-based deformable model guided by a stochastic force derived from a second-order Markov-Gibbs random field model that accounts for the object shape and appearance features. Then, the mid-wall of the segmented LV is determined based on estimating the centerline between the endocardium and epicardium of the LV. Finally, a geometrical Laplace-based method is proposed to track corresponding points on successive myocardial contours throughout the cardiac cycle in order to characterize the strain evolutions. The method was tested using simulated phantom images with predefined point locations of the LV wall throughout the cardiac cycle. The method was tested on 30 in vivo datasets to evaluate the feasibility of the proposed framework to index functional strain parameters. The cine MRI-based model agreed with the ground truth for functional metrics to within 0.30 % for indexing the peak systolic strain change and 0.29 % (per unit time) for indexing systolic and diastolic strain rates. The method was feasible for in vivo extraction of functional strain parameters. Strain indexes of the endocardium, mid-wall, and epicardium can be derived from routine cine images using automated techniques, thereby improving the utility of cine MRI data for characterization of myocardial function. Unlike traditional texture-based tracking, the

  4. Pathogenicity of rabies viruses isolated in China: two fixed strains and a street strain.

    Science.gov (United States)

    Huang, Ying; Tang, Qing; Rayner, Simon; Gong, Kai; Song, Bo; Liang, Guo Dong

    2013-07-01

    To investigate the virulence characteristics of two fixed strains (CTN and aG) and a street strain (HN10) of rabies viruses isolated in China. ICR mice of different age groups were inoculated with CTN, aG and HN10 rabies virus strains via the intracracerebral (i.c.) or intramuscular (i.m.) routes, and observed for 20 days. The CTN strain was pathogenic to 7-day-old suckling mice that received i.c. inoculations and 3-day-old suckling mice that received i.m. inoculations. The aG strain was pathogenic to 4-week-old mice that received i.c. inoculations and 7-day-old suckling mice that received i.m. inoculations. The HN10 strain was pathogenic to mice of all age groups via both inoculation routes. In moribund mice, the viruses had spread to most regions of the brain. The CTN and HN10 strains had similar dissemination patterns in the brain; both viral antigens could be found in the dentate gyrus (DG), whereas few viral antigens were present in the DG from specimens that had been infected with the aG strain. A comprehensive sequence analysis of the G protein suggested that differences in gene sequences may be responsible for producing strain-specific differences in pathogenicity and distribution in the brain. Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  5. Two strains of Crocosphaera watsonii with highly conserved genomes are distinguished by strain-specific features

    Directory of Open Access Journals (Sweden)

    Shellie Roxanne Bench

    2011-12-01

    Full Text Available Unicellular nitrogen-fixing cyanobacteria are important components of marine phytoplankton. Although non-nitrogen-fixing marine phytoplankton generally exhibit high gene sequence and genomic diversity, gene sequences of natural populations and isolated strains of Crocosphaera watsonii, one of two most abundant open ocean unicellular cyanobacteria groups, have been shown to be 98-100% identical.. The low sequence diversity in Crocosphaera is a dramatic contrast to sympatric species of Prochlorococcus and Synechococcus, and raises the question of how genome differences can explain observed phenotypic diversity among Crocosphaera strains. Here we show, through whole genome comparisons of two phenotypically different strains, that there are strain-specific sequences in each genome, and numerous genome rearrangements, despite exceptionally low sequence diversity in shared genomic regions. Some of the strain-specific sequences encode functions that explain observed phenotypic differences, such as exopolysaccharide biosynthesis. The pattern of strain-specific sequences distributed throughout the genomes, along with rearrangements in shared sequences is evidence of significant genetic mobility that may be attributed to the hundreds of transposase genes found in both strains. Furthermore, such genetic mobility appears to be the main mechanism of strain divergence in Crocosphaera which do not accumulate DNA microheterogeneity over the vast majority of their genomes. The strain-specific sequences found in this study provide tools for future physiological studies, as well as genetic markers to help determine the relative abundance of phenotypes in natural populations.

  6. Bone strain magnitude is correlated with bone strain rate in tetrapods: implications for models of mechanotransduction.

    Science.gov (United States)

    Aiello, B R; Iriarte-Diaz, J; Blob, R W; Butcher, M T; Carrano, M T; Espinoza, N R; Main, R P; Ross, C F

    2015-07-07

    Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar-canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone strain rate and gradient, but does not provide a mechanism for detection of strain magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because strain magnitude is an important determinant of skeletal fracture. Using strain gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between strain rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone strain magnitude is encoded in strain rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  7. Diversity of Bacillus anthracis Strains in Georgia and of Vaccine Strains from the Former Soviet Union

    Science.gov (United States)

    Merabishvili, Maya; Natidze, Merab; Rigvava, Sergo; Brusetti, Lorenzo; Raddadi, Noura; Borin, Sara; Chanishvili, Nina; Tediashvili, Marina; Sharp, Richard; Barbeschi, Maurizio; Visca, Paolo; Daffonchio, Daniele

    2006-01-01

    Despite the increased number of anthrax outbreaks in Georgia and the other Caucasian republics of the former Soviet Union, no data are available on the diversity of the Bacillus anthracis strains involved. There is also little data available on strains from the former Soviet Union, including the strains previously used for vaccine preparation. In this study we used eight-locus variable-number tandem repeat analyses to genotype 18 strains isolated from infected animals and humans at different sites across Georgia, where anthrax outbreaks have occurred in the last 10 years, and 5 strains widely used for preparation of human and veterinary vaccines in the former Soviet Union. Three different genotypes affiliated with the A3.a cluster were detected for the Georgian isolates. Two genotypes were previously shown to include Turkish isolates, indicating that there is a regional strain pattern in the South Caucasian-Turkish region. Four of the vaccine strains were polymorphic, exhibiting three different patterns of the cluster A1.a genotype and the cluster A3.b genotype. The genotype of vaccine strain 71/12, which is considered an attenuated strain in spite of the presence of both of the virulence pXO plasmids, appeared to be a novel genotype in the A1.a cluster. PMID:16885320

  8. The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding

    Energy Technology Data Exchange (ETDEWEB)

    Link, T.M.; Motta, A.T.; Koss, D.A. [Pennsylvania State Univ., University Park, PA (United States)

    1998-03-01

    The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.

  9. Ultrasound strain mapping of Achilles tendon compressive strain patterns during dorsiflexion.

    Science.gov (United States)

    Chimenti, Ruth L; Flemister, A Samuel; Ketz, John; Bucklin, Mary; Buckley, Mark R; Richards, Michael S

    2016-01-04

    Heel lifts are commonly prescribed to patients with Achilles tendinopathy, yet little is known about the effect on tendon compressive strain. The purposes of the current study were to (1) develop a valid and reliable ultrasound elastography technique and algorithm to measure compressive strain of human Achilles tendon in vivo, (2) examine the effects of ankle dorsiflexion (lowering via controlled removal of a heel lift and partial squat) on compressive strain of the Achilles tendon insertion and (3) examine the relative compressive strain between the deep and superficial regions of the Achilles tendon insertion. All tasks started in a position equivalent to standing with a 30mm heel lift. An ultrasound transducer positioned over the Achilles tendon insertion was used to capture radiofrequency images. A non-rigid image registration-based algorithm was used to estimate compressive strain of the tendon, which was divided into 2 regions (superficial, deep). The bland-Altman test and intraclass correlation coefficient were used to test validity and reliability. One-way repeated measures ANOVA was used to compare compressive strain between regions and across tasks. Compressive strain was accurately and reliably (ICC>0.75) quantified. There was greater compressive strain during the combined task of lowering and partial squat compared to the lowering (P=.001) and partial squat (Ptendon compared to the superficial for all tasks (P=.001). While these findings need to be examined in a pathological population, heel lifts may reduce tendon compressive strain during daily activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. CHROMOSOME TRANSFER KINETICS OF SALMONELLA HFR STRAINS.

    Science.gov (United States)

    JOHNSON, E M; FALKOW, S; BARON, L S

    1964-08-01

    Johnson, E. M. (Walter Reed Army Institute of Research, Washington, D.C.), Stanley Falkow, and L. S. Baron. Chromosome transfer kinetics of Salmonella Hfr strains. J. Bacteriol. 88:395-400. 1964.-The kinetics of chromosome transfer of an Hfr strain of Salmonella typhosa and an Hfr strain of S. typhimurium were examined in interrupted matings with multiply auxotrophic S. typhimurium recipients. The S. typhosa Hfr, TD-7, was found to transfer the pro-A, met-A, arg (A, C, F, or H), and ile markers at 8, 32, 36, and 51 min, respectively, after contact with the recipient strain. Comparison of these entry times with those of the analogous Escherichia coli Hfr P4X-6 for the same markers showed the gene order to be identical. However, the TD-7 entry times were considerably extended over those of P4X-6, which transfers these markers of E. coli F(-) strains at, respectively, 5, 20, 22.5, and 28 min. A similar extension of the entry times was noted with the S. typhimurium Hfr, SR-305, which transfers the markers in the reverse order, ile-met-A-pro-A, at 3 to 4, 18, and 46 min, respectively. Examination of P4X-6/Salmonella Hfr entry time ratios showed them to be constant at 0.63 for the earlier markers transferred by both TD-7 and SR-305. These data suggest that the physical length of the Salmonella chromosome is the same as that of E. coli, and that the rate of chromosome transfer of the Salmonella Hfr strains to S. typhimurium recipients is only 0.63 that of P4X-6 to E. coli F(-) strains under the same physical conditions.

  11. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

    Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004–2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site–station effects and source–path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal‐type classifications from the CRUST1.0 global velocity model, which demonstrates that high‐frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous strain records derived from triangulation of 137 high‐rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.

  12. Psychological strains found in the suicides of 72 celebrities.

    Science.gov (United States)

    Zhang, Jie; Tan, Jiandan; Lester, David

    2013-07-01

    The interpretation of suicide involves theories from many disciplines, and the strain theory of suicide is a social-psychological model that attempts to account for this complicated behavior. We have earlier explored the presence of psychological strains in a number of diverse samples of suicides and in the present study, we identified the strains experienced throughout the lives as documented in the biographies of 72 celebrities. The biographies were systematically identified through a number of requirements and composed by one of the authors of this study years before the strain theory of suicide was proposed. A graduate student coder, who was unaware of the strain theory of suicide, was hired to carry out a content analysis of the biography essays and categorize the life events and the responses of the suicide in terms of the four types of strains. Of the 72 suicides, one had no strains, one had all the four strains, four had only one, 30 had two, and 36 had three strains. The most common strain was aspiration strain (97%), followed by deprivation strain (89%), value strain (54%) and coping deficiency strain (4%). It is also noted that religious celebrities were more likely to experience value strain, while those celebrities who had experienced a downhill path in their careers were more likely to experience deprivation and coping strains. This analysis of the 72 celebrity suicides supported the strain theory of suicide. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. The Effect of Ivermectin in Seven Strains of Aedes aegypti (Diptera: Culicidae) Including a Genetically Diverse Laboratory Strain and Three Permethrin Resistant Strains

    Science.gov (United States)

    Deus, K. M.; Saavedra-rodriguez, K.; Butters, M. P.; Black, W. C.; Foy, B. D.

    2014-01-01

    Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all strains. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among strains, and all three permethrin-resistant strains were significantly less susceptible to ivermectin than the standard reference strain. The hatch rate after an ivermectin bloodmeal was less variable among strains, and only one of the permethrin-resistant strains differed significantly from the standard reference strain. Our studies suggest that ivermectin induces adult mortality and decreases the hatch rate of eggs through different mechanisms. A correlation analysis of log-transformed LC50 among strains suggests that permethrin and ivermectin cross-resistance may occur. PMID:22493855

  14. [Carbapenem-resistant Acinetobacter baumannii strains].

    Science.gov (United States)

    Bogiel, Tomasz; Kwiecińska-Piróg, Joanna; Jachna-Sawicka, Katarzyna; Gospodarek, Eugenia

    2010-01-01

    A. baumannii rods are opportunistic pathogens responsible generally for nosocomial infections. Resistance to carbapenems, observed among them, is a serious threat due to ability to be transmitted between bacterial species. The aim of our study was to evaluate the frequency of isolation and susceptibility to antibiotics of resistant to imipenem and/or meropenem A. baumannii strains isolated between 2007 and 2009 from patients of University Hospital of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Study shows increasing frequency of isolation that type of strains from 4 in 2007 to 95 in 2008 and 67 in 2009. Percentage of imipenem-resistant isolates raised to 27.6% in 2008 and 31.0% in 2009. Meropenem-resistant A. baumannii isolates frequency changed from 2.1% in 2007 to 31.2% and 34.6%, in 2008 and 2009, respectively. The majority of strains were obtained from patients of the Intensive Care Units and surgery clinics. Examined A. baumannii strains were generally isolated from bronchoalveolar lavage (25.3%) and wound (18.1%) or throat (12.0%) swabs samples. The isolates demonstrated full resistance to norfloxacin, ciprofloxacin, and chloramphenicol. Ampicillin/sulbactam (24.8%), tobramycin (8.1%) and colistin (1.5%) presented the highest in vitro activity against isolated strains.

  15. [Vancomycin-resistant Enterococcus spp. strains].

    Science.gov (United States)

    Kozuszko, Sylwia; Bogiel, Tomasz; Gospodarek, Eugenia

    2009-01-01

    The aim of our study was to evaluate a frequency of isolation and susceptibility to antibiotics of vancomycin-resistant enterococci isolated between 2005 and the first half of the 2009 from patients of University Hospital of Dr. A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruli. Study shows increasing frequency of VRE isolation from two in 2005, 8 in 2006, 30 in 2007 to 79 in 2008 and 40 in the first half of 2009 year. Among all isolated VRE strains E. faecium definitely predominated (75.0-90.0% in 2006-2009). The majority of strains were obtained from patients of the Pediatrics, Hematology and Oncology Clinic (43,4%) and Pediatric Surgery Clinic (41.5%). VRE strains were mainly isolated from digestive tract (79,9%). The isolates demonstrated frequently resistance to penicillin, ampicillin, ciprofloxacin, rifampicin and chloramphenicol. Percentage of VRE strain resistant to aminoglycosides decreased during the last four years of study. Over 56% of VRE isolates showed resistance to teicoplanin. Linezolid and quinupristin-dalfopristin were the only drugs presenting activity against isolated VRE strains.

  16. Strain differences in hippocampal EEG are related to strain differences in behaviour in rats

    NARCIS (Netherlands)

    Lier, H. van; Drinkenburg, W.H.I.M.; Coenen, A.M.L.

    2003-01-01

    To date, EEG studies towards strain differences have focussed on pharmacologically altered or pathological EEG activity, but only few studies have investigated strain differences and normal EEG activity. A strong relation between behaviour and EEG activity has been demonstrated, especially for

  17. Strain histograms are equal to strain ratios in predicting malignancy in breast tumours

    DEFF Research Database (Denmark)

    Carlsen, Jonathan Frederik; Ewertsen, Caroline; Sletting, Susanne

    2017-01-01

    Objectives: To assess whether strain histograms are equal to strain ratios in predicting breast tumour malignancy and to see if either could be used to upgrade Breast Imaging Reporting and Data System (BI-RADS) 3 tumours for immediate biopsy. Methods: Ninety-nine breast tumours were examined usin...

  18. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tension...... of principal overall strain. For other orientations surface instabilities are seen when non-associated plastic flow is taken into account. Compared to tension, smaller compressive deformations are needed in order to initiate a surface instability....... investigated, it is found that isotropic plasticity can only predict surface instabilities if non-associated plastic flow is accounted for. However, for anisotropic plasticity a surface instability is observed for associated plastic flow if the principal axes of anisotropy coincide with the directions...

  19. Survival and activity of individual bioaugmentation strains

    DEFF Research Database (Denmark)

    Dueholm, Morten Simonsen; G. Marquesa, Irina; Karst, Søren Michael

    2015-01-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now...... allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific...... qPCR and RT-qPCR tools for cell enumerations and expression of involved genes, stable isotope probing to follow growth on the target compounds and GFP-tagging to visualize the bioaugmentation strains directly in samples, all in combination with removal studies of the target compounds. The concept...

  20. MWCNTs based flexible and stretchable strain sensors

    Science.gov (United States)

    Khan, Saeed Ahmed; Gao, Min; Zhu, Yuechang; Yan, Zhuocheng; Lin, Yuan

    2017-06-01

    Carbon nanotubes have potential applications in flexible and stretchable devices due to their remarkable electromechanical properties. Flexible and stretchable strain sensors of multi-walled carbon nanotubes (MWCNTs) with aligned or random structures were fabricated on poly-dimethylsiloxane (PDMS) substrate with different techniques. It was observed that the spraycoatedtechniquebased strain sensor fabricated on PDMS substrate showed higher sensitivity higher stretchability, better linearity and excellent longer time stability than the sensor fabricated with other methods presented in this work. The scanning electron microscopy images indicated the spray coating technique can produce a better uniform and compact CNT network, which is the important role affecting the performance of CNT-based flexible strain sensors. Project supported by the National Basic Research Program of China (No. 2015CB351905), the National Natural Science Foundation of China (No. 61306015), the Technology Innovative Research Team of Sichuan Province of China (No.2015TD0005), and “111” Project (No. B13042)

  1. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains.

    Science.gov (United States)

    Pereira, Gabriela Andrade; Pimenta, Fabrícia Pires; Santos, Fátima Rejane Wink dos; Damasco, Paulo Vieira; Hirata Júnior, Raphael; Mattos-Guaraldi, Ana Luíza

    2008-08-01

    The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC tested. Although erythromycin (MIC90 0.75 microg/ml) and azithromycin (MIC90 0.064 microg/ml) were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 microg/ml) to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74%) showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

  2. Photo-induced strain imaging of semiconductors

    Directory of Open Access Journals (Sweden)

    Keiji Takata

    2017-04-01

    Full Text Available This paper presents a novel method for high-resolutions imaging of band-gap energies of semiconductors. When electron-hole pairs are generated in a semiconductor irradiated with a laser, they induce electronic strains in the semiconductor. The electronic strains can be detected and imaged by a scanning probe microscope. The electron-hole-pair generation depends on the band-gap and photon energies. When there are variations in band-gap energies in a sample, strains could be detected in regions having narrower gaps than the irradiated photon energy, and so their distributions can be imaged. The threshold of electron-hole-pair generation can be varied by changing the irradiated photon energies. Consequently, we can quantitatively image the band-gap energy distributions of semiconductors.

  3. Research of strain distribution and strain rate change in the fracture surroundings by the videoextensometric methode

    Directory of Open Access Journals (Sweden)

    M. Mihaliková

    2010-07-01

    Full Text Available The paper deals with the strain distribution and the strain rate of material in the surroundings of its fracture. Three steels applied in the automotive industry (DP - dual phase steel, microalloyed steel HR 45 and IF - interstitial free steel were used as the experimental material. The videoextensometric technique was used for sensing with CCD camera and computer. During the test, software records the coordinates of the centres of gravity of individual points, from which the respective strain values are then obtained. For individual steel grades, strain field maps in the fracture surroundings were plotted. The change in the strain rate in the fracture surroundings and at places more distant from the fracture was observed.

  4. The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Ulett, G.C.; Schembri, M.A.

    2006-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract....... The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory...... to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human...

  5. Quantitative assessment of viable cells of Lactobacillus plantarum strains in single, dual and multi-strain biofilms.

    Science.gov (United States)

    Fernández Ramírez, Mónica D; Kostopoulos, Ioannis; Smid, Eddy J; Nierop Groot, Masja N; Abee, Tjakko

    2017-03-06

    Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential

  6. Silicon-on-insulator interferometric strain sensor

    Science.gov (United States)

    Pearson, Graham N.; Jessop, Paul E.

    2003-06-01

    An integrated optical strain sensor based on a silicon-on-insulator (SOI) optical waveguide Mach-Zehnder interferometer has been demonstrated. The common problem of cross sensitivity to temperature changes has been greatly reduced by designing the lengths of the two interferometer arms to be exactly equal, in the absence of strain, so that thermally induced changes in the optical path lengths cancel out in the interference signal. The waveguide path in both arms of the interferometer has a long straight section and is folded back by a 180 degree bend. The straight section in one arm is perpendicular to that in the other arm so that the symmetry in the optical path lengths is broken when the applied strain in these two orthogonal directions is different. The interferometer output is thus a measure of the difference in strain along these two directions. For the initial device, the interferometer's size was approximately 15 x 15 mm, with the straight sections in each of the two arms being 12 mm long. For TM polarized light at a wavelength of 1.55 microns, the interferometer output intensity was observed to vary sinusoidally with applied uniaxial strain at a rate of 10 degrees per microstrain. This is in good agreement with the theoretical prediction. The strain sensitivity, as limited by system noise, was below one microstrain. SOI is an ideal material choice for this device. It is suitable for passive fiber alignment using V-groove techniques, and the ability to use small waveguide bending radii makes possible sensors that are more compact than has been demonstrated here.

  7. Nucleation versus instability race in strained films

    Science.gov (United States)

    Liu, Kailang; Berbezier, Isabelle; David, Thomas; Favre, Luc; Ronda, Antoine; Abbarchi, Marco; Voorhees, Peter; Aqua, Jean-Noël

    2017-10-01

    Under the generic term "Stranski-Krastanov" are grouped two different growth mechanisms of SiGe quantum dots. They result from the self-organized Asaro-Tiller-Grinfel'd (ATG) instability at low strain, while at high strain, from a stochastic nucleation. While these regimes are well known, we elucidate here the origin of the transition between these two pathways thanks to a joint theoretical and experimental work. Nucleation is described within the master equation framework. By comparing the time scales for ATG instability development and three-dimensional (3D) nucleation onset, we demonstrate that the transition between these two regimes is simply explained by the crossover between their divergent evolutions. Nucleation exhibits a strong exponential deviation at low strain while ATG behaves only algebraically. The associated time scale varies with exp(1 /x4) for nucleation, while it only behaves as 1 /x8 for the ATG instability. Consequently, at high (low) strain, nucleation (instability) occurs faster and inhibits the alternate evolution. It is then this different kinetic evolution which explains the transition from one regime to the other. Such a kinetic view of the transition between these two 3D growth regimes was not provided before. The crossover between nucleation and ATG instability is found to occur both experimentally and theoretically at a Ge composition around 50% in the experimental conditions used here. Varying the experimental conditions and/or the system parameters does not allow us to suppress the transition. This means that the SiGe quantum dots always grow via ATG instability at low strain and nucleation at high strain. This result is important for the self-organization of quantum dots.

  8. Pheromonal divergence between two strains of Spodoptera frugiperda

    NARCIS (Netherlands)

    Unbehend, M.; Hänniger, S.; Meagher, R.L.; Heckel, D.G.; Groot, A.T.

    2013-01-01

    Spodoptera frugiperda consists of two genetically and behaviorally different strains, the corn- and the rice-strain, which seem to be in the process of sympatric speciation. We investigated the role of strain-specific sexual communication as a prezygotic mating barrier between both strains by

  9. Characterization of Integrated Optical Strain Sensors Based on Silicon Waveguides

    NARCIS (Netherlands)

    Westerveld, W.J.; Leinders, S.M.; Muilwijk, P.M.; Pozo, J.

    2013-01-01

    Microscale strain gauges are widely used in micro electro-mechanical systems (MEMS) to measure strains such as those induced by force, acceleration, pressure or sound. We propose all-optical strain sensors based on micro-ring resonators to be integrated with MEMS. We characterized the strain-induced

  10. Unsteady Aerodynamic Force Sensing from Strain Data

    Science.gov (United States)

    Pak, Chan-Gi

    2017-01-01

    A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm.

  11. Low Strain Rate Failure of Compliant Flexures

    Science.gov (United States)

    2011-10-01

    exponentials, also known as a Prony series. 22 Distribution A: Approved for public release; distribution is unlimited. FA8655-10-1-3065 M. Santer, Imperial...dependent stress σ(t) may be represented by the Prony series σ(t) = ∂W ∂ϵ ( 1− ∑ i wi ( 1− e−t/τi )) (6) in which W is the strain energy, wi are a set of...such a viscoelastic material hypothe- sis could replicate the observed strain evolution behavior. A single term Prony series representation is

  12. Miniature ultrasonic transducers with optical strain readout

    Science.gov (United States)

    Lee, Chung-Hoon; Lal, Amit

    1999-09-01

    In this paper we demonstrate the use of diffractive gratings to optically measure strain in miniature ultrasonic transducers. Aluminum diffraction gratings were fabricated on silicon-microfabricated ultrasonic horns and beams which were actuated by bonded piezoelectric PZT (Lead-Zirconate Titanate) plates. A He-Ne laser beam was diffracted from the grating and a knife-edge was used to measure small changes in the diffraction angle as a result of time varying grating space and width. The measured strain and displacement profiles agreed with the expected mode patterns for the silicon resonators.

  13. Cells as strain-cued automata

    Science.gov (United States)

    Cox, Brian N.; Snead, Malcolm L.

    2016-02-01

    We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions other than those implied by external energy gradients. Evidence of cells acting as strain-cued automata have been inferred from patterns observed in nature and from experiments conducted in vitro. Simulations that mimic particular cases of pattern forming share the idealization that cells are assumed to pass information among themselves solely via mechanical boundary conditions, i.e., the tractions and displacements present at their membranes. This assumption opens three mechanisms for pattern formation in large cell populations: wavelike behavior, kinematic feedback in cell motility that can lead to sliding and rotational patterns, and directed migration during invasions. Wavelike behavior among ameloblast cells during amelogenesis (the formation of dental enamel) has been inferred from enamel microstructure, while strain waves in populations of epithelial cells have been observed in vitro. One hypothesized kinematic feedback mechanism, "enhanced shear motility", accounts successfully for the spontaneous formation of layered patterns during amelogenesis in the mouse incisor. Directed migration is exemplified by a theory of invader cells that sense and respond to the strains they themselves create in the host population as they invade it: analysis shows that the strain fields contain positional information that could aid the formation of cell network structures, stabilizing the slender geometry of branches and helping govern the frequency of branch bifurcation and branch coalescence (the formation of closed networks). In simulations of pattern formation in

  14. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  15. Dynamics of Dual Infection with Campylobacter jejuni Strains in Chickens Reveals Distinct Strain-to-Strain Variation in Infection Ecology

    Science.gov (United States)

    Wigley, Paul; Humphrey, Suzanne; Kemmett, Kirsty; Lacharme-Lora, Lizeth; Humphrey, Tom; Williams, Nicola

    2014-01-01

    Although multiple genotypes of Campylobacter jejuni may be isolated from the same commercial broiler flock, little is known about the infection dynamics of different genotypes within individuals or their colonization sites within the gut. Single experimental infections with C. jejuni M1 (sequence type 137, clonal complex 45) and C. jejuni 13126 (sequence type 21, clonal complex 21) revealed that 13126 colonized the ceca at significantly higher levels. The dissemination and colonization sites of the two C. jejuni strains then were examined in an experimental broiler flock. Two 33-day-old broiler chickens were infected with M1 and two with 13126, and 15 birds were left unchallenged. Cloacal swabs were taken postinfection to determine the colonization and shedding of each strain. By 2 days postinfection (dpi), 8/19 birds were shedding M1 whereas none were shedding 13126. At 8 dpi, all birds were shedding both strains. At 18 dpi, liver and cecal levels of each isolate were quantified, while in 10 birds they also were quantified at nine sites throughout the gastrointestinal (GI) tract. 13126 was found throughout the GI tract, while M1 was largely restricted to the ceca and colon. The livers of 7/19 birds were culture positive for 13126 only. These data show that 13126 has a distinctly different infection biology than strain M1. It showed slower colonization of the lower GI tract but was more invasive and able to colonize at a high level throughout the GI tract. The finding that C. jejuni strains have markedly different infection ecologies within the chicken has implications for control in the poultry industry and suggests that the contamination risk of edible tissues is dependent on the isolate involved. PMID:25107966

  16. Probiotic Potential of Lactobacillus Strains with Antimicrobial Activity against Some Human Pathogenic Strains

    Science.gov (United States)

    Shokryazdan, Parisa; Sieo, Chin Chin; Kalavathy, Ramasamy; Liang, Juan Boo; Alitheen, Noorjahan Banu; Faseleh Jahromi, Mohammad; Ho, Yin Wan

    2014-01-01

    The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits. PMID:25105147

  17. Probiotic Potential of Lactobacillus Strains with Antimicrobial Activity against Some Human Pathogenic Strains

    Directory of Open Access Journals (Sweden)

    Parisa Shokryazdan

    2014-01-01

    Full Text Available The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits.

  18. Probiotic potential of Lactobacillus strains with antimicrobial activity against some human pathogenic strains.

    Science.gov (United States)

    Shokryazdan, Parisa; Sieo, Chin Chin; Kalavathy, Ramasamy; Liang, Juan Boo; Alitheen, Noorjahan Banu; Faseleh Jahromi, Mohammad; Ho, Yin Wan

    2014-01-01

    The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits.

  19. Electronic and optical properties of strained graphene and other strained 2D materials: a review

    Science.gov (United States)

    Naumis, Gerardo G.; Barraza-Lopez, Salvador; Oliva-Leyva, Maurice; Terrones, Humberto

    2017-09-01

    This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

  20. Electronic and optical properties of strained graphene and other strained 2D materials: a review.

    Science.gov (United States)

    Naumis, Gerardo G; Barraza-Lopez, Salvador; Oliva-Leyva, Maurice; Terrones, Humberto

    2017-09-01

    This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-07-01

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-950l. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate the viscoelastic based model show that the observed characteristic behavior is captured by this model.

  2. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  3. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  4. A self-supporting strain transducer

    Science.gov (United States)

    Hoffman, I. S.

    1973-01-01

    Self-contained mechanical measuring system is handmounted by simply compressing installation spring and inserting device into hole of matching size. It is self-aligning as each contact pin maintains constant contact with surface being measured. Strain level is controlled by design to provide for measurements over almost unlimited number of load cycles.

  5. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

    Directory of Open Access Journals (Sweden)

    Gabriela Andrade Pereira

    2008-08-01

    Full Text Available The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 µg/ml to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 µg/ml and azithromycin (MIC90 0.064 µg/ml were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 µg/ml to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74% showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

  6. Relation between job strain and myocardial infarction

    DEFF Research Database (Denmark)

    Netterstrøm, B; Nielsen, F E; Kristensen, T S

    1999-01-01

    to MI were job category (blue collar workers v white collar workers, OR 2.8 (1.6 to 5.8)), and employment sector (private v public, OR 3.1 (1.8 to 6.1)). CONCLUSIONS: Thus, the study confirmed the job strain model as well as the well known association between socioeconomic status and risk of MI, whereas...

  7. Evolution and Strain Variation in BCG.

    Science.gov (United States)

    Abdallah, Abdallah M; Behr, Marcel A

    2017-01-01

    BCG vaccines were derived by in vitro passage, during the years 1908-1921, at the Pasteur Institute of Lille. Following the distribution of stocks of BCG to vaccine production laboratories around the world, it was only a few decades before different BCG producers recognized that there were variants of BCG, likely due to different passaging conditions in the different laboratories. This ultimately led to the lyophilization of stable BCG products in the 1950s and 1960s, but not before considerable evolution of the different BCG strains had taken place. The application of contemporary research methodologies has now revealed genomic, transcriptomic and proteomic differences between BCG strains. These molecular differences in part account for phenotypic differences in vitro between BCG strains, such as their variable secretion of antigenic proteins. Yet, the relevance of BCG variability for immunization policy remains elusive. In this chapter we present an overview of what is known about BCG evolution and its resulting strain variability, and provide some speculation as to the potential relevance for a vaccine given to over 100 million newborns each year.

  8. Characterization and monitoring of selected rhizobial strains ...

    African Journals Online (AJOL)

    SERVER

    2007-06-18

    Jun 18, 2007 ... sulfated methyl fucose (Ferro et al., 2000). Nearly full- length 16S rRNA sequences and partial 23S rRNA sequences confirmed that two isolates from D. retusa were highly similar or identical to Bradyrhizobium strains isolated from the legumes Erythrina and Clitoria (Papilio- noideae tribe Phaseoleae) in ...

  9. Thermal strain analysis of optic fiber sensors.

    Science.gov (United States)

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2013-01-31

    An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating.

  10. Thermal Strain Analysis of Optic Fiber Sensors

    Directory of Open Access Journals (Sweden)

    Chih-Ying Huang

    2013-01-01

    Full Text Available An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating.

  11. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

    frequently encounter high substrate concentrations, low pH, high temperatures and various inhibitory compounds originating either from the raw material used or from cellular metabolism. The aim of this research project is to develop robust platform strains of Saccharomyces cerevisiae based on industrial...

  12. Plane strain problem in microstretch elastic solid

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    MS received 17 February 2000; revised 1 August 2003. Abstract. The eigenvalue approach is developed for the two-dimensional plane strain problem in a microstretch elastic medium. Applying Laplace and Fourier transforms, an infinite space subjected to a concentrated force is studied. The inte- gral transforms are ...

  13. Strain Analysis of the de Mattia Test

    Directory of Open Access Journals (Sweden)

    Reiter M.

    2010-06-01

    Full Text Available The de Mattia test is a well-known, standardized and widely used method in the rubber industry for characterizing the fatigue behaviour of rubbers. Due to the visual observation and classification of the crack initiated, high data scatter were usually observed in these tests. To improve the quality of the de Mattia test and to support the applicability of the test method in modern design procedures, two novel experimental methods were proposed. Full-field strain analysis experiments using digital image correlation technique were performed and the local strains at the notch tip determined in the first. A global displacement vs. local strain calibration curves makes the design and conduction of strain based Wöhler curves possible. The crack initiation and crack growth is detected by an image analysis system and the crack growth rate was determined in the second method. To gain more insight into the fatigue behaviour of rubbers, these two novel methods were combined and can efficiently be used for characterizing the fatigue behaviour of rubbers.

  14. Strain Analysis of the de Mattia Test

    Science.gov (United States)

    Feichter, C.; Vezer, S.; Reiter, M.; Major, Z.

    2010-06-01

    The de Mattia test is a well-known, standardized and widely used method in the rubber industry for characterizing the fatigue behaviour of rubbers. Due to the visual observation and classification of the crack initiated, high data scatter were usually observed in these tests. To improve the quality of the de Mattia test and to support the applicability of the test method in modern design procedures, two novel experimental methods were proposed. Full-field strain analysis experiments using digital image correlation technique were performed and the local strains at the notch tip determined in the first. A global displacement vs. local strain calibration curves makes the design and conduction of strain based Wöhler curves possible. The crack initiation and crack growth is detected by an image analysis system and the crack growth rate was determined in the second method. To gain more insight into the fatigue behaviour of rubbers, these two novel methods were combined and can efficiently be used for characterizing the fatigue behaviour of rubbers.

  15. Survival and activity of individual bioaugmentation strains.

    Science.gov (United States)

    Dueholm, Morten S; Marques, Irina G; Karst, Søren M; D'Imperio, Seth; Tale, Vaibhav P; Lewis, Derrick; Nielsen, Per Halkjær; Nielsen, Jeppe Lund

    2015-06-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific qPCR and RT-qPCR tools for cell enumerations and expression of involved genes, stable isotope probing to follow growth on the target compounds and GFP-tagging to visualize the bioaugmentation strains directly in samples, all in combination with removal studies of the target compounds. The concept of the approach is demonstrated through a case study involving degradation of aromatic hydrocarbons in activated sludge augmented with the bioaugmentation strain Pseudomonas monteilii SB3078. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Preliminary characterization of Rhizobium strains isolated from ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... range of carbohydrates and salts of organic acids as carbon sources which are also diagnostic for root nodule bacteria (Sa et al., 1993; Rodriguez-Navarro et al., 2000;. Zerhari et al., 2000). Utilizasation of different compounds by strains, as sole carbon and nitrogen sources is one of the most useful traits for ...

  17. Polyhydroxyalkanoate (PHA) production by Lynisibacillus sp. strain ...

    African Journals Online (AJOL)

    ... thermoplastic produced from renewable bioresources and is hence attracting attention as a plastic material for use in the environment and medical fields. In the present study, the Lynisibacillus sp. strain UEA-20.171 was selected for production of polyhydroxyalkanoate (PHA) in bioreactor. The accumulation of polymer in ...

  18. Evolution and Strain Variation in BCG

    KAUST Repository

    Abdallah, Abdallah

    2017-11-07

    BCG vaccines were derived by in vitro passage, during the years 1908–1921, at the Pasteur Institute of Lille. Following the distribution of stocks of BCG to vaccine production laboratories around the world, it was only a few decades before different BCG producers recognized that there were variants of BCG, likely due to different passaging conditions in the different laboratories. This ultimately led to the lyophilization of stable BCG products in the 1950s and 1960s, but not before considerable evolution of the different BCG strains had taken place. The application of contemporary research methodologies has now revealed genomic, transcriptomic and proteomic differences between BCG strains. These molecular differences in part account for phenotypic differences in vitro between BCG strains, such as their variable secretion of antigenic proteins. Yet, the relevance of BCG variability for immunization policy remains elusive. In this chapter we present an overview of what is known about BCG evolution and its resulting strain variability, and provide some speculation as to the potential relevance for a vaccine given to over 100 million newborns each year.

  19. Antifungal and antibacterial compounds from Streptomyces strains ...

    African Journals Online (AJOL)

    In addition, antibacterial activity of this strain was determined against human pathogenic bacteria such as. Staphylococcus aureus, Klebsiella pneumoniae, Kocuria ... aureus (MRSA). The present results indicate that isolate KEH23 is a potential antibiotic producer agent for the biocontrol of plant and human pathogens.

  20. Anisotropic Thermoplasticty and Strain Localization in Shale

    Science.gov (United States)

    Semnani, S. J.; White, J. A.; Borja, R. I.

    2016-12-01

    Sedimentary rocks such as shale are inherently anisotropic due to their layered structure, and sensitive to temperature changes caused by various engineering applications e.g. carbon sequestration, waste disposal, wellbore drilling, as well as geothermal and heat storage applications. These materials are also prone to strain localization in the form of a shear band when subjected to critical loads. Strain localization is generally considered as a manifestation of material instability, which has been linked traditionally to failure of materials. While isotropic material models simplify the modeling process, they fail to accurately describe the mechanical behavior and onset of instability in anisotropic rocks. We present a thermo-plastic framework for modeling the coupled thermo-mechanical response and for predicting the inception of a shear band in shale using the general framework of critical state plasticity and the specific framework of modified Cam-Clay model. Under the assumption of infinitesimal deformation, the formulation incorporates anisotropy in both elastic and plastic responses. The model is first calibrated using experimental data from triaxial tests to demonstrate its capability in capturing anisotropy in the mechanical response. Subsequently, stress-point simulations of strain localization are carried out under two different conditions, namely, isothermal localization and adiabatic localization. The adiabatic formulation investigates the effect of temperature on localization via thermo-mechanical coupling. Numerical simulations are presented to demonstrate the effect of anisotropy, hardening, and thermal softening on strain localization.

  1. Life Stress, Strain, and Deviance Across Schools: Testing the Contextual Version of General Strain Theory in China.

    Science.gov (United States)

    Zhang, Jinwu; Liu, Jianhong; Wang, Xin; Zou, Anquan

    2017-08-01

    General Strain Theory delineates different types of strain and intervening processes from strain to deviance and crime. In addition to explaining individual strain-crime relationship, a contextualized version of general strain theory, which is called the Macro General Strain Theory, has been used to analyze how aggregate variables influence aggregate and individual deviance and crime. Using a sample of 1,852 students (Level 1) nested in 52 schools (Level 2), the current study tests the Macro General Strain Theory using Chinese data. The results revealed that aggregate life stress and strain have influences on aggregate and individual deviance, and reinforce the individual stress-deviance association. The current study contributes by providing the first Macro General Strain Theory test based on Chinese data and offering empirical evidence for the multilevel intervening processes from strain to deviance. Limitations and future research directions are discussed.

  2. Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains.

    Science.gov (United States)

    Maassen, C B; van Holten-Neelen, C; Balk, F; den Bak-Glashouwer, M J; Leer, R J; Laman, J D; Boersma, W J; Claassen, E

    2000-05-22

    Different Lactobacillus strains are frequently used in consumer food products. In addition, recombinant lactobacilli which contain novel expression vectors can now be used in immunotherapeutic applications such as oral vaccination strategies and in T cell tolerance induction approaches for autoimmune disease. Both for food and clinical applications of lactobacilli, proper selection of wild type strains is crucial. For that purpose, eight different common Lactobacillus strains were analysed with respect to mucosal induction of pro- and anti-inflammatory cytokines, IgA-producing plasma cells in the gut, as well as systemic antibody responses against a parenterally administered antigen. Immunohistochemical analysis of cytokine-producing cells in the gut villi showed no significant induction of the cytokines IL-1alpha, IFN-gamma, IL-4 or IL-10 after oral administration of wild type Lactobacillus strains. In contrast, oral administration of L. reuteri and L. brevis induced expression of the proinflammatory/Th1 cytokines TNF-alpha, IL-2 and/or IL-1beta. Oral administration of these two strains and L. fermentum also significantly enhanced the IgG response against parenterally administered haptenated chicken gamma globulin (TNP-CGG). The five other strains did not show this adjuvanticity. L. reuteri induced relatively high levels of IgG2a compared to L. murines, a nonadjuving Lactobacillus strain. These findings imply that different Lactobacillus strains induce distinct mucosal cytokine profiles and possess differential intrinsic adjuvanticity. This suggests that rational Lactobacillus strain selection provides a strategy to influence cytokine expression and thereby influence immune responses.

  3. Hot Electron Injection into Uniaxially Strained Silicon

    Science.gov (United States)

    Kim, Hyun Soo

    In semiconductor spintronics, silicon attracts great attention due to the long electron spin lifetime. Silicon is also one of the most commonly used semiconductor in microelectronics industry. The spin relaxation process of diamond crystal structure such as silicon is dominant by Elliot-Yafet mechanism. Yafet shows that intravalley scattering process is dominant. The conduction electron spin lifetime measured by electron spin resonance measurement and electronic measurement using ballistic hot electron method well agrees with Yafet's theory. However, the recent theory predicts a strong contribution of intervalley scattering process such as f-process in silicon. The conduction band minimum is close the Brillouin zone edge, X point which causes strong spin mixing at the conduction band. A recent experiment of electric field-induced hot electron spin relaxation also shows the strong effect of f-process in silicon. In uniaxially strained silicon along crystal axis [100], the suppression of f-process is predicted which leads to enhance electron spin lifetime. By inducing a change in crystal structure due to uniaxial strain, the six fold degeneracy becomes two fold degeneracy, which is valley splitting. As the valley splitting increases, intervalley scattering is reduced. A recent theory predicts 4 times longer electron spin lifetime in 0.5% uniaxially strained silicon. In this thesis, we demonstrate ballistic hot electron injection into silicon under various uniaxial strain. Spin polarized hot electron injection under strain is experimentally one of the most challenging part to measure conduction electron spin lifetime in silicon. Hot electron injection adopts tunnel junction which is a thin oxide layer between two conducting materials. Tunnel barrier, which is an oxide layer, is only 4 ˜ 5 nm thick. Also, two conducting materials are only tens of nanometer. Therefore, under high pressure to apply 0.5% strain on silicon, thin films on silicon substrate can be easily

  4. Recent advances in echocardiography: strain and strain rate imaging [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Oana Mirea

    2016-04-01

    Full Text Available Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications.

  5. A comparison of brazed metal and epoxied fibre Bragg grating strain sensors under high strain regimes

    Science.gov (United States)

    Mckeeman, I.; Niewczas, P.; Khan, S.

    2017-04-01

    Three different fibre Bragg grating strain sensors were tested for their suitability for measuring high strain. The sensor types were: a bare epoxied fibre Bragg grating, a standard fibre Bragg grating epoxied into a metal capillary and, finally, a metal coated fibre Bragg grating brazed into a metal capillary. The sensors were calibrated on a steel specimen up to 1400MPa (equivalent to 7.3mɛ). The results show that the bare epoxied Bragg grating and the metal packaged grating are suitable for measuring strains of this level.

  6. Intermediate strain rate testing methodologies and full-field optical strain measurement techniques for composite materials characterisation

    OpenAIRE

    Longana, M.L.

    2014-01-01

    Two optical full-field strain measurement techniques, Digital Image Correlation and the Grid Method, are applied to characterise the strain-rate dependent constitutive behaviour of composite materials. Optical strain measurement techniques based on full-field images are well established for material characterisation in the quasi-static strain rate region, however in this work they are developed to study the material behaviour at intermediate strain rates, which is relatively unexplored. For t...

  7. Strain rate effects for spallation of concrete

    Directory of Open Access Journals (Sweden)

    Häussler-Combe Ulrich

    2015-01-01

    Full Text Available Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property – which can be covered by rate dependent stress strain relations – or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  8. Characterization of autochthonous Lactobacillus paracasei strains on potential probiotic ability

    Directory of Open Access Journals (Sweden)

    Zorica Radulović

    2010-06-01

    Full Text Available Lactic acid bacteria strains isolated from traditional made cheeses constitute a reservoir of unexplored potential in biotechnology. In this study four autochthonous lactobacilli strains, isolated from traditional white brined cheeses and identified as Lactobacillus paracasei (08, 564, 05 and 02, were investigated on potential probiotic ability. The investigation comprised sensitivity to simulated gastrointestinal tract conditions, antimicrobial activity against wide range of pathogens, antibiotic resistance as well as autoaggregation ability. Lactobacillus rhamnosus GG was used as referent strain. Three tested strains grew well in simulated gastrointestinal conditions, but their sensitivity was greater on bile acids and pancreatin compared with pepsin low pH 2.5. The examined strains had different sensitivity to antibiotics, but three strains showed very good antimicrobial activity to pathogens. All strains demonstrated very good autoaggregation ability. For three of four examined strains of Lb. paracasei probiotic potential was similar with referent strain Lb. rhamnosus GG, determined in vitro

  9. First strains of the genus Kluyvera in Czechoslovakia.

    Science.gov (United States)

    Aldová, E; Hausner, O; Svihálková, A; Láznicková, K; Sobotková, J; Smolka, J; Horácková, O

    1985-08-01

    Fourteen of 21 strains isolated from stools, urine specimens and the hospital environment were identified as Kluyvera. All of these 14 strains corresponded with the literary description of the genus Kluyvera and were identical with two reference strains except that one of them failed to utilize sodium acetate within 7 days. One strain (No. 23441) produced massive growth on Jordan's tartrate, which some Kluyvera do. Important in differentiating indole- and Simmons' citrate-negative Kluyvera strains from Escherichia vulneris (two other of our 21 strains) is negative ornithin decarboxylase and negative Christensen citrate in the latter. Three strains were identified as Citrobacter, where especially indole-positive and urease-negative strains may be reminiscent of Kluyvera. An aberrant strain, No. 25115, which alone failed to grow at 42 degrees C and by some characters differed from Kluyvera, E. vulneris and Enteric Group 10, was identified as E. coli.

  10. Influences of misfit strains on liquid phase heteroepitaxial growth

    Science.gov (United States)

    Lu, Yanli; Peng, Yingying; Yu, Genggeng; Chen, Zheng

    2017-10-01

    Influences of misfit strains with different signs on liquid phase heteroepitaxial growth are studied by binary phase field crystal model. It is amazing to find that double islands are formed because of lateral and vertical separation. The morphological evolution of epitaxial layer depends on signs of misfit strains. The maximum atomic layer thickness of double islands under negative misfit strain is larger than that of under positive misfit strain at the same evolutional time, and size differences between light and dark islands is much smaller under negative misfit strain than that of under positive misfit strain. In addition, concentration field and density field approximately have similar variational law along x direction under the same misfit strain but show opposite variational trend under misfit strains with different signs. Generally, free energy of epitaxial growth systems keeps similar variational trend under misfit strains with different signs.

  11. Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains

    NARCIS (Netherlands)

    Maassen, C.B.M.; Holten-Neelen, C. van; Balk, F.; Bak-Glashouwer, M.-J.H. den; Leer, R.J.; Laman, J.D.; Boersma, W.J.A.; Claassen, E.

    2000-01-01

    Different Lactobacillus strains are frequently used in consumer food products. In addition, recombinant lactobacilli which contain novel expression vectors can now be used in immunotherapeutic applications such as oral vaccination strategies and in T cell tolerance induction approaches for

  12. Strain measurement within a single-lap joint using embedded strain gages

    Science.gov (United States)

    Tuttle, M. E.; Barthelemy, B. M.; Brinson, H. F.

    1984-01-01

    An experimental method used to measure the in-plane normal-axial strains produced within a single-lap joint is described in which a resistance-foil strain gage is embedded within the joint prior to curing of the adhesive. Nominal dimensions of the titanium Ti-6-4 adherends were 0.13 x 2.5 x 12.7 cm and an overlap of 2.5 cm was used. The joint was bonded with FM-300 structural adhesive. The average ultimate shear strength of the gaged specimens and control specimens was 16.1 MPa and 14.1 MPa. A significant advantage of the proposed method is that strains internal to the joint are measured, rather than strains at an external edge. The presence of the gage was found to be not detrimental to bond performance.

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

    DEFF Research Database (Denmark)

    Janezic, Sandra; Zidaric, Valerija; Pardon, Bart

    2014-01-01

    Background: Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria...... countries). Conclusions: This results show that although PCR ribotype 078 is often reported as the major animal C. difficile type, especially in pigs, the variability of strains in pigs and other animal hosts is substantial. Most common human PCR ribotypes (014/020 and 002) are also among most prevalent...... animal associated C. difficile strains worldwide. The widespread dissemination of toxigenic C. difficile and the considerable overlap in strain distribution between species furthers concerns about interspecies, including zoonotic, transmission of this critically important pathogen....

  14. Development of quantitative PCR and metagenomics-based approaches for strain quantification of a defined mixed-strain starter culture.

    Science.gov (United States)

    Johansen, Pernille; Vindeløv, Jannik; Arneborg, Nils; Brockmann, Elke

    2014-05-01

    Although the strain composition of mixed cultures may hugely affect production of various fermented foods, such as e.g. cheese, tools for investigating it have so far been limited. In this study, two new approaches for quantification of seven Lactococcus lactis subsp. cremoris strains (S1-S7) in a defined mixed-strain starter culture were developed and verified. By mapping NGS reads from 47 sequenced L. lactis strains to de novo assembly contigs of the seven strains, two strain-specific sequence regions (SEQ1 and SEQ2) were identified for each strain for qPCR primer design (A1 and A2). The qPCR assays amplified their strain-specific sequence region target efficiently. Additionally, high reproducibility was obtained in a validation sample containing equal amounts of the seven strains, and assay-to-assay coefficients of variance (CVs) for six (i.e. S1, S2, S4-S7) of the seven strains correlated to the inter-plate CVs. Hence, at least for six strains, the qPCR assay design approach was successful. The metagenomics-based approach quantified the seven strains based on average coverage of SEQ1 and SEQ2 by mapping sequencing reads from the validation sample to the strain-specific sequence regions. Average coverages of the SEQ1 and SEQ2 in the metagenomics data showed CVs of ≤17.3% for six strains (i.e. S1-S4, S6, S7). Thus, the metagenomics-based quantification approach was considered successful for six strains, regardless of the strain-specific sequence region used. When comparing qPCR- and metagenomics-based quantifications of the validation sample, the identified strain-specific sequence regions were considered suitable and applicable for quantification at a strain level of defined mixed-strain starter cultures. Copyright © 2014 Elsevier GmbH. All rights reserved.

  15. Robust mutant strain design by pessimistic optimization.

    Science.gov (United States)

    Apaydin, Meltem; Xu, Liang; Zeng, Bo; Qian, Xiaoning

    2017-10-03

    Flux Balance Analysis (FBA) based mathematical modeling enables in silico prediction of systems behavior for genome-scale metabolic networks. Computational methods have been derived in the FBA framework to solve bi-level optimization for deriving "optimal" mutant microbial strains with targeted biochemical overproduction. The common inherent assumption of these methods is that the surviving mutants will always cooperate with the engineering objective by overproducing the maximum desired biochemicals. However, it has been shown that this optimistic assumption may not be valid in practice. We study the validity and robustness of existing bi-level methods for strain optimization under uncertainty and non-cooperative environment. More importantly, we propose new pessimistic optimization formulations: P-ROOM and P-OptKnock, aiming to derive robust mutants with the desired overproduction under two different mutant cell survival models: (1) ROOM assuming mutants have the minimum changes in reaction fluxes from wild-type flux values, and (2) the one considered by OptKnock maximizing the biomass production yield. When optimizing for desired overproduction, our pessimistic formulations derive more robust mutant strains by considering the uncertainty of the cell survival models at the inner level and the cooperation between the outer- and inner-level decision makers. For both P-ROOM and P-OptKnock, by converting multi-level formulations into single-level Mixed Integer Programming (MIP) problems based on the strong duality theorem, we can derive exact optimal solutions that are highly scalable with large networks. Our robust formulations P-ROOM and P-OptKnock are tested with a small E. coli core metabolic network and a large-scale E. coli iAF1260 network. We demonstrate that the original bi-level formulations (ROOM and OptKnock) derive mutants that may not achieve the predicted overproduction under uncertainty and non-cooperative environment. The knockouts obtained by the

  16. Bioconjugation with strained alkenes and alkynes.

    Science.gov (United States)

    Debets, Marjoke F; van Berkel, Sander S; Dommerholt, Jan; Dirks, A Ton J; Rutjes, Floris P J T; van Delft, Floris L

    2011-09-20

    The structural complexity of molecules isolated from biological sources has always served as an inspiration for organic chemists. Since the first synthesis of a natural product, urea, chemists have been challenged to prepare exact copies of natural structures in the laboratory. As a result, a broad repertoire of synthetic transformations has been developed over the years. It is now feasible to synthesize organic molecules of enormous complexity, and also molecules with less structural complexity but prodigious societal impact, such as nylon, TNT, polystyrene, statins, estradiol, XTC, and many more. Unfortunately, only a few chemical transformations are so mild and precise that they can be used to selectively modify biochemical structures, such as proteins or nucleic acids; these are the so-called bioconjugation strategies. Even more challenging is to apply a chemical reaction on or in living cells or whole organisms; these are the so-called bioorthogonal reactions. These fields of research are of particular importance because they not only pose a worthy challenge for chemists but also offer unprecedented possibilities for studying biological systems, especially in areas in which traditional biochemistry and molecular biology tools fall short. Recent years have seen tremendous growth in the chemical biology toolbox. In particular, a rapidly increasing number of bioorthogonal reactions has been developed based on chemistry involving strained alkenes or strained alkynes. Such strained unsaturated systems have the unique ability to undergo (3 + 2) and (4 + 2) cycloadditions with a diverse set of complementary reaction partners. Accordingly, chemistry centered around strain-promoted cycloadditions has been exploited to precisely modify biopolymers, ranging from nucleic acids to proteins to glycans. In this Account, we describe progress in bioconjugation centered around cycloadditions of these strained unsaturated systems. Being among the first to recognize the utility

  17. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Directory of Open Access Journals (Sweden)

    Moriah L Szpara

    2011-10-01

    Full Text Available Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1 and 2, and varicella zoster virus (VZV. These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV, causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs, a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit

  18. Hole doped Dirac states in silicene by biaxial tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-03-11

    The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.

  19. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Energy Technology Data Exchange (ETDEWEB)

    Oliva-Leyva, M., E-mail: moliva@fisica.unam.mx [Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 20-364, 01000 México, Distrito Federal (Mexico); Naumis, Gerardo G., E-mail: naumis@fisica.unam.mx [Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 20-364, 01000 México, Distrito Federal (Mexico); School of Physics Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States)

    2015-10-23

    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation and the true shift of the Dirac point. Pseudomagnetic fields are thus explained by means of position-dependent Dirac cones, whereas complex gauge fields appear as a consequence of a position-dependent Fermi velocity. Also, position-dependent Fermi velocity effects on the spinor wavefunction are considered for interesting cases of deformations such as flexural modes. - Highlights: • The relevance of the strain-induced Dirac point shift to obtain the anisotropic Fermi velocity is shown. • An appropriate expression of the position-dependent Fermi velocity is reported. • A position-dependent Fermi velocity induces an inhomogeneity in the carrier probability density.

  20. Strain and strain rate echocardiography findings in children with asymptomatic congenital aortic stenosis.

    Science.gov (United States)

    Dogan, Vehbi; Öcal, Burhan; Orun, Utku Arman; Ozgur, Senem; Yılmaz, Osman; Keskin, Mahmut; Ceylan, Ozben; Karademir, Selmin; Şenocak, Filiz

    2013-06-01

    The aim of our study was to evaluate myocardial functions with strain/strain rate echocardiography in asymptomatic patients having congenital aortic stenosis (CAS) with normal cardiac functions as determined by conventional echocardiographic techniques and comparing them with those of healthy controls. A total of 58 patients with various degrees of isolated CAS and 52 healthy controls were enrolled in this study. Conventional and two-dimensional speckle tracking (2DSTE) echocardiography were performed. Global longitudinal strain (LS) (-23.1 ± 3.6 and -23.8 ± 4.7), and longitudinal strain rate (LSR) (-1.49 ± 0.32 and -1.76 ± 0.39) values were lower, whereas circumferential strain (CS) (-25.9 ± 4.7 and -22.8 ± 6.4) and circumferential strain rate (CSR) (-1.82 ± 0.46 and -1.69 ± 0.49) values were greater in the patient group than in the control subjects. The difference was significant for global LSR and CS (p children with CAS. Impairment of LV long-axis function occurred earlier and was more prominent in basal parts of the interventricular septum and the free wall of the left ventricle.

  1. Creep Strain and Strain Rate Response of 2219 Al Alloy at High Stress Levels

    Science.gov (United States)

    Taminger, Karen M. B.; Wagner, John A.; Lisagor, W. Barry

    1998-01-01

    As a result of high localized plastic deformation experienced during proof testing in an International Space Station connecting module, a study was undertaken to determine the deformation response of a 2219-T851 roll forging. After prestraining 2219-T851 Al specimens to simulate strains observed during the proof testing, creep tests were conducted in the temperature range from ambient temperature to 107 C (225 F) at stress levels approaching the ultimate tensile strength of 2219-T851 Al. Strain-time histories and strain rate responses were examined. The strain rate response was extremely high initially, but decayed rapidly, spanning as much as five orders of magnitude during primary creep. Select specimens were subjected to incremental step loading and exhibited initial creep rates of similar magnitude for each load step. Although the creep rates decreased quickly at all loads, the creep rates dropped faster and reached lower strain rate levels for lower applied loads. The initial creep rate and creep rate decay associated with primary creep were similar for specimens with and without prestrain; however, prestraining (strain hardening) the specimens, as in the aforementioned proof test, resulted in significantly longer creep life.

  2. Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Lacroute, Y.; Markey, L.; Salazar, M.; Vignal, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France)

    2011-05-15

    Research highlights: > Surface strains measured using nanogauge were compared to the texture obtained by EBSD. > Statistics of the principal strain discern the grains according to the Schmid factor. > Strain hotspots were localized near a triple junction of alloy 600 under tensile loading. > Asymetrical profile of the GB strains is a criterion for surface cracking initiation. - Abstract: A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then investigated both statistically for each grain and locally at the grain boundaries. The superimposition of microstructure and strain maps allows the high strain gradient (reaching 3-fold the applied strain) to be localized at preferential grain boundaries near the triple junction. The Schmid factors and the KAM were compared to the maximum principal strain and the in-plane shear strain respectively. The polycrystalline deformation was attributable first to the rotation of some grains, followed by the elongation of all grains along their preferential activated slip systems.

  3. SNIT: SNP identification for strain typing

    Directory of Open Access Journals (Sweden)

    Reifman Jaques

    2011-09-01

    Full Text Available Abstract With ever-increasing numbers of microbial genomes being sequenced, efficient tools are needed to perform strain-level identification of any newly sequenced genome. Here, we present the SNP identification for strain typing (SNIT pipeline, a fast and accurate software system that compares a newly sequenced bacterial genome with other genomes of the same species to identify single nucleotide polymorphisms (SNPs and small insertions/deletions (indels. Based on this information, the pipeline analyzes the polymorphic loci present in all input genomes to identify the genome that has the fewest differences with the newly sequenced genome. Similarly, for each of the other genomes, SNIT identifies the input genome with the fewest differences. Results from five bacterial species show that the SNIT pipeline identifies the correct closest neighbor with 75% to 100% accuracy. The SNIT pipeline is available for download at http://www.bhsai.org/snit.html

  4. Strain induced highly oriented graphene wrinkles

    Science.gov (United States)

    Wang, Wen; Yang, Shudu; Wang, Ashu

    2017-07-01

    Graphene, a two-dimensional (2D) material, is an important constituent part for the development of mechanic, electronic and photonic systems due to its remarkable properties, however, wrinkling is a ubiquitous phenomenon in 2D membranes. As a 2D material with atomic thickness, graphene is found to be wrinkled easily because of its relatively low bending rigidity, and besides, wrinkle affects graphene’s remarkable physical property severely. Despite their prevalence and potential impact on large-scale graphene properties, only a several approaches have been dedicated to control their structural morphology and orientation by transferring graphene onto polymer substrates. Here we report a new route to control the orientation of wrinkles by directly applying external mechanical strains to metal substrates until plastic deformation happens. By changing direction and magnitude of tension strain, wrinkles with different spacing but all with orientations perpendicular to the tensile direction can be obtained.

  5. Transfer induced compressive strain in graphene

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  6. OTDR strain gauge for smart skins

    Energy Technology Data Exchange (ETDEWEB)

    Kercel, S.W.

    1993-09-01

    Optical time-domain reflectometry (OTDR) is a simple and rugged technique for measuring quantities such as strain that affect the propagation of light in an optical fiber. For engineering applications of OTDR, it is important to know the repeatable limits of its performance. The author constructed an OTDR-based, submillimeter resolution strain measurement system from off-the-shelf components. The systems repeatably resolves changes in time of flight to within {plus_minus}2 ps. Using a 1-m, single-mode fiber as a gauge and observing the time of flight between Fresnel reflections, a repeatable sensitivity of 400 microstrains was observed. Using the same fiber to connect the legs of a 3-dB directional coupler to form a loop, a repeatable sensitivity of 200 microstrains was observed. Realizable changes to the system that should improve the repeatable sensitivity to 20 microstrains or less are discussed.

  7. Dynamic strain aging in Haynes 282 superalloy

    Directory of Open Access Journals (Sweden)

    Hörnqvist Magnus

    2014-01-01

    Full Text Available Haynes 282 is a newly introduced Ni-based superallony, developed to provide a combination of high-temperature mechanical properties, thermal stability and processability. The present contribution investigates the effect of dynamic strain aging (DSA on the deformation behaviour of Haynes 282 during monotonic and cyclic loading. It is shown that DSA (presumably related to carbon diffusion based on rough estimates of the activation energy completely dominates the development of the stress during cycling at intermediate temperatures, leading to extensive cyclic hardening and serrated yielding. However, no clear effects on the fatigue life or the resulting dislocation structure could be observed. The tensile properties were not severely affected, in spite of the presence of extensive serrated yielding, although a reduction in ductility was observed in the DSA temperature regime. During monotonic loading at lower strain rates indications of an additional DSA mechanism due to substitutional elements were observed.

  8. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... a linear elastic specimen to reach a state of constant strain rate before fracture. This was in contrast to ductile materials, which are widely tested with for the High-speed servohydraulic test machine. The development of the analysis and the interpretation of the results, were based on the experience...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...

  9. Statistics of twinning in strained ferroelastics

    Science.gov (United States)

    Ding, Xiangdong; Aktas, Oktay; Wang, Xiaofei; Li, Suzhi; Zhao, Ziyuan; Zhang, Libo; He, Xiaomei; Lookman, Turab; Saxena, Avadh; Sun, Jun

    2017-10-01

    In this review, we show that the evolution of the microstructure and kinetics of ferroelastic crystals under external shear can be explored by computer simulations of 2D model materials. We find that the nucleation and propagation of twin boundaries in ferroelastics depend sensitively on temperature. In the plastic regime, the evolution of the ferroelastic microstructure under strain deformation maintains a stick-and-slip mechanism in all temperature regimes, whereas the dynamic behavior changes dramatically from power-law statistics at low temperature to a Kohlrausch law at intermediate temperature, and then to a Vogel-Fulcher law at high temperature. In the yield regime, the distribution of jerk energies follows power-law statistics in all temperature regimes for a large range of strain rates. The non-spanning avalanches in the yield regime follow a parabolic temporal profile. The changes of twin pattern and twin boundaries density represent an important step towards domain boundary engineering.

  10. A Novel Strain Gauge with Damping Capability

    Directory of Open Access Journals (Sweden)

    Xiaohua LI

    2009-10-01

    Full Text Available The goal of this work is to investigate the properties of a new type of multifunctional composite which is based on multi-walled carbon nanotubes (MWCNT. The composite was prepared from a paper like MWCNT film which was sandwiched between two adhesive layers. Two point probe and four point probe methods were used to test its mechanical strain sensing properties. Nanoindentation and direct shear tests were used to acquire the Young’s modulus and shear modulus of MWCNT film composite. Its structural damping properties were investigated via a free vibration test. This new type of carbon nanotube based composite may potentially serve simultaneously as both a strain gauge and a damping treatment for use in structural vibration control.

  11. A Tunable Strain Sensor Using Nanogranular Metals

    Directory of Open Access Journals (Sweden)

    Friedemann Völklein

    2010-11-01

    Full Text Available This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals.

  12. Strain monitoring of a composite wing

    Science.gov (United States)

    Strathman, Joseph; Watkins, Steve E.; Kaur, Amardeep; Macke, David C.

    2016-04-01

    An instrumented composite wing is described. The wing is designed to meet the load and ruggedness requirements for a fixed-wing unmanned aerial vehicle (UAV) in search-and-rescue applications. The UAV supports educational systems development and has a 2.1-m wingspan. The wing structure consists of a foam core covered by a carbon-fiber, laminate composite shell. To quantify the wing characteristics, a fiber-optic strain sensor was surface mounted to measure distributed strain. This sensor is based on Rayleigh scattering from local index variations and it is capable of high spatial resolution. The use of the Rayleigh-scattering fiber-optic sensors for distributed measurements is discussed.

  13. Embedded silicon nanocrystal interface structure and strain

    Science.gov (United States)

    Shenoy, Bhamy Maithry; Hegde, G. M.; Mahapatra, D. Roy

    2018-01-01

    The structure of nanocrystal-matrix interface and strain in embedded nanocrystals are studied using large-scale atomistic simulations, with the examples of Si nanocrystal embedded in amorphous matrix of SiO2. Photoluminescence from silicon nanocrystals embedded in a dielectric matrix like SiO2 and Si3N4 are promising for Si-based optical devices. The nanocrystal-matrix interface plays a crucial role in understanding its optical and electrical properties. Nanocrystals with diameters varying from 2.17 to 4.56 nm are studied. A detailed quantitative analysis of the variation of Si/SiO2 interface structure and strain distribution with nanocrystal diameter is reported. A linear variation of the interface width with nanocrystal diameter is observed with thinner interfaces for larger nanocrystals. Local deformation analysis reveals that the smaller nanocrystals are highly strained, whereas the strain in the larger ones shifts to the interface. This is in accordance with observed increase in total percentage of defect states in the interface from 39 to 70 % for diameter increasing from 2.17 to 4.56 nm. Moreover, based on the atomic arrangements at the interface, optically active defects like Pb centres, E centres and non-bridging oxygen centres are identified and a dominance of Pb centres is observed for all the nanocrystals. The detailed structural characterization-related investigations using the proposed simulation approach will find useful application in designing system-level response of embedded nanocrystals and also to correlate various experimental observations.

  14. PNNL Stress/Strain Correlation for Zircaloy

    Energy Technology Data Exchange (ETDEWEB)

    Geelhood, Kenneth J.; Beyer, Carl E.; Luscher, Walter G.

    2008-07-18

    Pacific Northwest National Laboratory (PNNL) was tasked with incorporating cladding mechanical property data into the Nuclear Regulatory Commission (NRC) fuel codes, FRAPCON-31 and FRAPTRAN2, by the NRC Office of Nuclear Reactor Research. The objective of that task was to create a mechanical model that can calculate true stress, true strain, and the possible failure of the fuel rod cladding based on uniaxial test data.

  15. Systems strategies for developing industrial microbial strains

    DEFF Research Database (Denmark)

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different...... performance under industrial fermentation conditions. These challenges can be overcome by taking systems approaches through the use of state-of-the-art tools of systems biology, synthetic biology and evolutionary engineering in the context of industrial bioprocess. Major systems metabolic engineering...

  16. Note on Strain Release Variation with Depth

    Directory of Open Access Journals (Sweden)

    A. G. GALANOPOULOS

    1964-06-01

    Full Text Available In the present paper an attempt is made to approach
    the problem of the upper mantle structure by studying the strain relea.se
    variation with depth. If the method and data used in this paper are adequate,
    we may be allowed to say that although there is no strain release
    evidence for the depth of the upper boundary of the asthenospliere zone on
    account of lack of adequate accuracy in the determination of focal depths,
    nevertheless there is ample indication of a discontinuity at about 125 km
    depth. The abrupt change in the rate of decrease in the strain release
    with depth near this level clearly indicates that a sudden decrease in the
    yield strength of the material in the earth should occur at about this depth.
    I t might even be possible to think that the melting point of some kind of
    crystal grains or rocks in the earth is attained at that depth. However,
    this does not involve a completely molten state. This state should rather
    occur at depths where there is a complete lack of strain release. Regionally
    this state is attained at different depths, but in some regions the partially
    molten state, i. e. the heterogeneity of the mantle, probably recurs or increases
    due to the pressure increase or some other reason and reaches a minor
    maximum beyond which it might be possible to speculate that the heterogeneity
    of the mantle falls off rapidly and a continuous layer of material
    in molten state covers the whole earth. If data from other sources will
    confirm this structure, there will be good reasons to think of redefining
    the upper boundaries of surface and intermediate shocks at depths of 125
    and 425 km or thereabouts, respectively.

  17. Development of an Onboard Strain Recorder

    Science.gov (United States)

    1990-01-01

    Amidships Electrical Resistance N/A _________________ -____________ (PAS) ______ MOSSIER STATE Fore A Aft Strains Main Deck Amidships Electrical...Vu’in 1 1/4" 1 21 Conduit WOLVERINE STATE N/A N/A N/A CALIFORNIA OEM N/A NIA N/A MOSSIER STATE N/A N/A N/A MR1CCNN/A N/A N/A EDWAD L. RYERSON N/A N/A

  18. Strain Analysis of the de Mattia Test

    OpenAIRE

    Reiter M; Vezer S.; Feichter C.; Major Z.

    2010-01-01

    The de Mattia test is a well-known, standardized and widely used method in the rubber industry for characterizing the fatigue behaviour of rubbers. Due to the visual observation and classification of the crack initiated, high data scatter were usually observed in these tests. To improve the quality of the de Mattia test and to support the applicability of the test method in modern design procedures, two novel experimental methods were proposed. Full-field strain analysis experiments usi...

  19. Molecular evolution of GII-4 Norovirus strains.

    Directory of Open Access Journals (Sweden)

    Katherina Zakikhany

    Full Text Available BACKGROUND: Human Noroviruses (NoV are the major cause of acute nonbacterial gastroenteritis and the leading cause of outbreaks of gastroenteritis worldwide. Genotype II-4 (GII-4 NoV has been shown to spread rapidly and is the most commonly detected strain worldwide, particularly in association with outbreaks. Previously, we have shown that circulating GII-4 NoV strains exist as populations of selectively neutral variants, and that the emergence of epidemic GII-4 NoV strains correlated with mutations in at least two key sites (Sites A and B within the P2 domain of the surface exposed major capsid protein (VP1. METHODOLOGY: We developed a rapid pyrosequencing method for screening of the two Sites A and B and a homology based modelling system was used to predict the effects of amino acid substitutions at these sites on the antigenic properties of the virus (defined as surface motif types. PRINCIPLE FINDING/CONCLUSION: Here, we describe the characterisation of amino acid diversity at Sites A and B for 1062 GII-4 NoV strains from clinical specimen associated with outbreak of gastroenteritis (2000-2011 and 250 GII-4 NoV sequences from Genbank. Our data identified a high diversity of different Site A and B site combinations at amino acid level and amino acid diversity was higher at Site B than Site A. Site A motifs could be grouped into 3 clusters based on similar surface motif types. We predict that Site A is a major epitope on the virus surface, responsible for defining the antigenic profile, and a more subtle role for Site B, maintaining minor antigenic variation within the virus population.

  20. Elastic strain engineering in silicon and silicon-germanium nanomembranes

    Science.gov (United States)

    Paskiewicz, Deborah Marie

    Strain in crystalline materials alters the atomic symmetry, thereby changing materials properties. Controlling the strain allows tunability of these new properties. Elastic strain engineering in crystalline nanomembranes (NMs) provides ways to induce and relax strain in thin sheets of single-crystalline materials without exposing the material to the formation of extended defects. I use strain engineering in NMs in two ways: (1) elastic strain sharing between multiple layers using the crystalline symmetry of the layers to induce unique strain distributions, and (2) complete elastic relaxation of single-crystalline alloy NMs. In both cases, NM strain engineering methods enable the introduction of unique strain profiles or strain relaxation in ways not compatible with conventional bulk processing, where strain destroys the long-range crystallinity. Elastically strain-shared NMs are fabricated by releasing multi-layer thin film heterostructures from the original host substrate. If one layer of the original heterostructure contains strain, the strain will share between the layers of the freestanding NM. The extent of strain sharing will depend on the relative thicknesses, the ratio of the elastic moduli between the materials, and elastic symmetry of the layers. I calculate strain distributions in flat NMs between layers with 2-fold and 4-fold elastic symmetry. I verify my calculations with experimental proof of two examples: (1) strain sharing between biaxially isotropic layers, Si/SiGe/Si(001), and (2) strain sharing between biaxially anisotropic layers, Si/SiGe/Si(110). Strain engineering in NMs is also used to relax strain elastically in thin materials that are difficult to fabricate with conventional bulk crystal growth techniques. Thin films of SiGe grow uniformly and elastically strained on Si substrates. I release the SiGe layer from the Si growth template with NM fabrication processes and allow the SiGe allow to relax elastically to the appropriate bulk lattice

  1. Mycotoxin-degradation profile of Rhodococcus strains.

    Science.gov (United States)

    Cserháti, M; Kriszt, B; Krifaton, Cs; Szoboszlay, S; Háhn, J; Tóth, Sz; Nagy, I; Kukolya, J

    2013-08-16

    Mycotoxins are secondary fungal metabolites that may have mutagenic, carcinogenic, cytotoxic and endocrine disrupting effects. These substances frequently contaminate agricultural commodities despite efforts to prevent them, so successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins is a novel strategy that shows potential for application in food and feed processing. In this study we investigated the mycotoxin degradation ability of thirty-two Rhodococcus strains on economically important mycotoxins: aflatoxin B1, zearalenone, fumonisin B1, T2 toxin and ochratoxin A, and monitored the safety of aflatoxin B1 and zearalenone degradation processes and degradation products using previously developed toxicity profiling methods. Moreover, experiments were performed to analyse multi-mycotoxin-degrading ability of the best toxin degrader/detoxifier strains on aflatoxin B1, zearalenone and T2 toxin mixtures. This enabled the safest and the most effective Rhodococcus strains to be selected, even for multi-mycotoxin degradation. We concluded that several Rhodococcus species are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Strain sensors for high field pulse magnets

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Christian [Los Alamos National Laboratory; Zheng, Yan [Los Alamos National Laboratory; Easton, Daniel [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory

    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.

  3. Social relations: network, support and relational strain.

    Science.gov (United States)

    Due, P; Holstein, B; Lund, R; Modvig, J; Avlund, K

    1999-03-01

    We introduce a conceptual framework with social relations as the main concept and the structure and the function of social relations as subconcepts. The structure of social relations covers aspects of formal relations and social network. The function of social relations covers social support, social anchorage and relational strain. We use this conceptual framework to describe social relations in the Danish population, with questionnaire data from the Danish Longitudinal Health Behaviour Study including a random sample of each of the age groups 25-, 50-, 60-and 70-year olds, N = 2,011. The postal questionnaires were answered by a random sample in each of the age groups. The results show marked age and gender differences in both the structure and the function of social relations. The social network, measured as weekly contacts, weakens with age and so does instrumental support. Emotional support is unrelated to this decline in contact frequency and appears to be at the same level for younger and older individuals. Relational strain, measured as conflicts, declines with age for all kinds of social relations. The weakening of the social network with age does not seem to affect the level of emotional support and in turn seems to be partly compensated for by a simultaneous decline in relational strain.

  4. Integrated strain array for cellular mechanobiology studies

    Science.gov (United States)

    Simmons, C. S.; Sim, J. Y.; Baechtold, P.; Gonzalez, A.; Chung, C.; Borghi, N.; Pruitt, B. L.

    2011-05-01

    We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblasts on the device for 6 h. At higher strains, cells and actin stress fibers realign with a circumferential preference.

  5. Genetic characterization of measles vaccine strains.

    Science.gov (United States)

    Bankamp, Bettina; Takeda, Makoto; Zhang, Yan; Xu, Wenbo; Rota, Paul A

    2011-07-01

    The complete genomic sequences of 9 measles vaccine strains were compared with the sequence of the Edmonston wild-type virus. AIK-C, Moraten, Rubeovax, Schwarz, and Zagreb are vaccine strains of the Edmonston lineage, whereas CAM-70, Changchun-47, Leningrad-4 and Shanghai-191 were derived from 4 different wild-type isolates. Nucleotide substitutions were found in the noncoding regions of the genomes as well as in all coding regions, leading to deduced amino acid substitutions in all 8 viral proteins. Although the precise mechanisms involved in the attenuation of individual measles vaccines remain to be elucidated, in vitro assays of viral protein functions and recombinant viruses with defined genetic modifications have been used to characterize the differences between vaccine and wild-type strains. Although almost every protein contributes to an attenuated phenotype, substitutions affecting host cell tropism, virus assembly, and the ability to inhibit cellular antiviral defense mechanisms play an especially important role in attenuation. Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.

  6. Shewanella strain isolated from black powder

    Energy Technology Data Exchange (ETDEWEB)

    Lutterbach, Marcia T.S.; Contador, Luciana S.; Oliveira, Ana Lucia C.; Galvao, Mariana M. [National Institute of Technology (INT), Rio de Janeiro, RJ (Brazil); Pimenta, Gutemberg S. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Black powder is a term frequently used to refer to residues formed by various types of iron sulfides mixed with contaminants eventually present in the natural gas flow. According to some researchers, the occurrence of black powder in gas pipelines, besides its chemical corrosion origin, can be directly related to the sulfate-reducing bacteria (SRB) metabolism in this environment. A black powder sample was inoculated in a Post gate E medium modified with the addition of thioglycolate. The resulting positive culture was kept in the laboratory for four years until its use. A dilution technique was then performed aiming to isolate an SRB strain. The bacterial strain isolated and identified through DNA sequencing was not an SRB but rather a Shewanella sp. Compared to the sulfate-reducing bacteria group-traditionally considered the foremost responsible for microbially-influenced corrosion (MIC) - Shewanella is a facultative anaerobe and has a versatile metabolism. Shewanella is able to reduce ferric iron and sulfite, oxidize hydrogen gas, and produce hydrogen sulfide; therefore, these bacteria can be responsible for MIC and pit formation. The isolated Shewanella was used in a corrosion experiment, and the corrosion products were characterized by X-ray diffraction, identifying iron sulfides, iron oxides, and sulfur. Our results indicate that the strain isolated, S. putrefaciens, plays a key role in corrosion problems in gas pipelines. (author)

  7. Ultrafast vascular strain compounding using plane wave transmission

    NARCIS (Netherlands)

    Hansen, H.H.G.; Saris, A.E.C.M.; Vaka, N.R.; Nillesen, M.M.; Korte, C.L. de

    2014-01-01

    Deformations of the atherosclerotic vascular wall induced by the pulsating blood can be estimated using ultrasound strain imaging. Because these deformations indirectly provide information on mechanical plaque composition, strain imaging is a promising technique for differentiating between stable

  8. Genetic variations among Mycoplasma bovis strains isolated from Danish cattle

    DEFF Research Database (Denmark)

    Kusiluka, L.J.M.; Kokotovic, Branko; Ojeniyi, B.

    2000-01-01

    The genetic heterogeneity of Mycoplasma bovis strains isolated in Denmark over a 17-year period was investigated. Forty-two field strains isolated from different geographic locations and specimens, including strains from 21 herds involved in two outbreaks of M. bovis-induced mastitis, and the type....... Among the analyzed strains, 18 different AFLP profiles were detected. The similarity between individual fingerprints, calculated by Dice similarity coefficient, ranged from 0.9 to 1.0. Twenty-five strains, including 23 which were isolated during two outbreaks of M. bovis-induced mastitis which occurred...... 2 years apart; showed indistinguishable AFLP patterns. More genetic diversify was observed among the recent strains. The similarity of the genotypes of the field strains to that of the M. bovis type strain (PG45(T)) was 97.7%. The results of this study have demonstrated a remarkable genomic...

  9. Teacher Interrupted: Work Stress, Strain, and Teaching Role

    National Research Council Canada - National Science Library

    Mulholland, Rosie; McKinlay, Andy; Sproule, John

    2013-01-01

    ...) presented a unique opportunity to compare teachers’ perception of strain with a “general” and “clinical” population. Positive correlations were observed between work stress and strain...

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  11. Thermal and Cardiovascular Strain from Hypohydration: Influence of Exercise Intensity

    National Research Council Canada - National Science Library

    Montain, S

    1996-01-01

    ...) strain induced from hypohydration during heat stress. We hypothesized that the added thermal and cardiovascular strain induced by hypohydration would be greater during high intensity than low intensity exercise...

  12. Whole Genome Analysis of a Wine Yeast Strain

    Science.gov (United States)

    Hauser, Nicole C.; Fellenberg, Kurt; Gil, Rosario; Bastuck, Sonja; Hoheisel, Jörg D.

    2001-01-01

    Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 and the standard laboratory background in S288c. Our analysis shows that even under normal conditions, logarithmic growth in YPD medium, the two strains have expression patterns that differ significantly in more than 40 genes. Subsequent studies indicated that these differences correlate with small changes in promoter regions or variations in gene copy number. Blotting copy numbers vs. transcript levels produced patterns, which were specific for the individual strains and could be used for a characterization of unknown samples. PMID:18628902

  13. Assigning strains to bacterial species via the internet

    National Research Council Canada - National Science Library

    Bishop, Cynthia J; Aanensen, David M; Jordan, Gregory E; Kilian, Mogens; Hanage, William P; Spratt, Brian G

    2009-01-01

    .... The advantage of this approach (multilocus sequence analysis; MLSA) is that, for any group of related species, a strain database can be produced and combined with software that allows query strains to be assigned to species via the internet...

  14. Introducing lattice strain to graphene encapsulated in hBN

    Science.gov (United States)

    Tomori, Hikari; Hiraide, Rineka; Ootuka, Youiti; Watanabe, Kenji; Taniguchi, Takashi; Kanda, Akinobu

    Due to the characteristic lattice structure, lattice strain in graphene produces an effective gauge field. Theories tell that by controlling spatial variation of lattice strain, one can tailor the electronic state and transport properties of graphene. For example, under uniaxial local strain, graphene exhibits a transport gap at low energies, which is attractive for a graphene application to field effect devices. Here, we develop a method for encapsulating a strained graphene film in hexagonal boron-nitride (hBN). It is known that the graphene carrier mobility is significantly improved by the encapsulation of graphene in hBN, which has never been applied to strained graphene. We encapsulate graphene in hBN using the van der Waals assembly method. Strain is induced by sandwiching a graphene film between patterned hBN sheets. Spatial variation of strain is confirmed with micro Raman spectroscopy. Transport measurement of encapsulated strained graphene is in progress.

  15. Strain predominance following exposure of vaccinated and naive pregnant gilts to multiple strains of porcine reproductive and respiratory syndrome virus.

    Science.gov (United States)

    Lager, Kelly M; Mengeling, William L; Wesley, Ronald D

    2003-05-01

    Two studies were performed in order to test the relative ability of different strains of porcine reproductive and respiratory syndrome virus (PRRSV) to replicate and cross the placental barrier in pregnant gilts. Study 1 comprised 6 nonvaccinated gilts. Study 2 comprised 8 nonvaccinated gilts and 12 gilts that were vaccinated twice before conception. On, or about, gestation day 90 all gilts were simultaneously exposed to 20 field strains of PRRSV (all strains were distinguishable by restriction fragment length polymorphism (RFLP) patterns). Gilts of study 1 were euthanized on day 7 postpartum. Gilts of study 2 were euthanized on, or about, gestation day 111. All gilts, pigs, and fetuses were tested for the presence and type of strain of PRRSV. Of 128 samples shown to contain PRRSV, 118 contained a single strain, 4 contained 2 strains, and 2 contained a strain or strains for which the RFLP pattern was undecipherable. Only 8 of the 20 strains were isolated from nonvaccinated gilts and their litters. And only 2 of the 20 strains (notably 2 of the same strains isolated from nonvaccinated gilts and their litters), were isolated from vaccinated gilts and their litters. Moreover, 1 of the 2 strains accounted for most (31 of 37; 84%) of the isolates from the vaccinated group. Collectively these results indicate that strains differ in their ability to replicate in pregnant gilts and cross the placental barrier. And they suggest that maternal immunity, although sometimes insufficient to prevent transplacental infection, can exert additional selective pressure.

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

    KAUST Repository

    Tahini, H. A.

    2012-04-17

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

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

    Science.gov (United States)

    Tahini, H; Chroneos, A; Grimes, R W; Schwingenschlögl, U; Dimoulas, A

    2012-05-16

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

  18. Wireless Passive Strain Sensor Based on Surface Acoustic Wave Devices

    OpenAIRE

    Nomura, T.; Kawasaki, K.; Saitoh, A

    2008-01-01

    Surface acoustic wave (SAW) devices offer many attractive features for applications as chemical and physical sensors. In this paper, a novel SAW strain sensor that employs SAW delay lines has been designed. Two crossed delay lines were used to measure the two-dimensional strain. A wireless sensing system is also proposed for effective operation of the strain sensor. In addition, an electronic system for accurately measuring the phase characteristics of the signal wave from the passive strain ...

  19. Ultrafast vascular strain compounding using plane wave transmission

    OpenAIRE

    Hansen, H.H.G.; Saris, A.E.C.M.; Vaka, N.R.; Nillesen, M.M.; de Korte, C.L.

    2014-01-01

    Deformations of the atherosclerotic vascular wall induced by the pulsating blood can be estimated using ultrasound strain imaging. Because these deformations indirectly provide information on mechanical plaque composition, strain imaging is a promising technique for differentiating between stable and vulnerable atherosclerotic plaques. This paper first explains 1-D radial strain estimation as applied intravascularly in coronary arteries. Next, recent methods for noninvasive vascular strain es...

  20. Heavy metal resistance by two bacteria strains isolated from a ...

    African Journals Online (AJOL)

    The strain DX-T3-03 had a larger range of antibiotic resistance than DX-T3-01. On the basis of 16S rDNA sequencing, the two strains were identified as Ralstonia pickettii strain DX-T3-01 and Sphingomonas sp. strain DX-T3-03, respectively. This study supplied potential bacterial materials for tailing bioremediation in the ...

  1. Long term strain behavior of PMMA based polymer optical fibers

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Nielsen, Kristian; Woyessa, Getinet

    2015-01-01

    We are reporting on the viscoelasticity of PMMA based Fiber Bragg Grating (FBG) strain sensors when exposed to repeated sequences of long term strain and relaxation with various duty-cycles. In terms of the FBG wavelength and how it follows the strain cycle, we have shown that in the small strain...... duration, for the same relaxation time, this range will be shortened, which might influence the sensing capabilities of the fiber sensor....

  2. Antimicrobial resistance of bacterial strains isolated from orange ...

    African Journals Online (AJOL)

    ... obtained for the strains of S. aureus. The MIC for cloxacillin was 0.1-1.0mg/ml for E. coli strains, and 0.01-1.0mg/ml for S. aureus strains. In all, ten strains of the bacterial isolates had evidence for the production of β-lactamases. Key words: Orange juice, antibiotics, resistance pattern, β-lactamase, microbiological standard.

  3. Ultra-responsive soft matter from strain-stiffening hydrogels

    NARCIS (Netherlands)

    Jaspers, M.; Dennison, M.; Mabesoone, M.F.J.; MacKintosh, F.C.; Rowan, A.E.; Kouwer, P.H.J.

    2014-01-01

    The stiffness of hydrogels is crucial for their application. Naturea(tm) s hydrogels become stiffer as they are strained. This stiffness is not constant but increases when the gel is strained. This stiffening is used, for instance, by cells that actively strain their environment to modulate their

  4. Strain improvement of Gluconacetobacter xylinus NCIM 2526 for ...

    African Journals Online (AJOL)

    GHEM4 gave cellulose yield of 5.96 g/l which was 50% more than the parent strain (GHUV4) and 98% more than the wild strain (NCIM 2526). The results indicated that UV and EMS were effective mutagenic agents for strain improvement. Key words: Bacterial cellulose, Gluconacetobacter xylinus, ultraviolet mutagenesis, ...

  5. Bordetella pertussis Strain Lacking Pertactin and Pertussis Toxin.

    Science.gov (United States)

    Williams, Margaret M; Sen, Kathryn; Weigand, Michael R; Skoff, Tami H; Cunningham, Victoria A; Halse, Tanya A; Tondella, M Lucia

    2016-02-01

    A Bordetella pertussis strain lacking 2 acellular vaccine immunogens, pertussis toxin and pertactin, was isolated from an unvaccinated infant in New York State in 2013. Comparison with a French strain that was pertussis toxin-deficient, pertactin wild-type showed that the strains carry the same 28-kb deletion in similar genomes.

  6. Biochemical Characterization of Prion Strains in Bank Voles

    Directory of Open Access Journals (Sweden)

    Romolo Nonno

    2013-07-01

    Full Text Available Prions exist as different strains exhibiting distinct disease phenotypes. Currently, the identification of prion strains is still based on biological strain typing in rodents. However, it has been shown that prion strains may be associated with distinct PrPSc biochemical types. Taking advantage of the availability of several prion strains adapted to a novel rodent model, the bank vole, we investigated if any prion strain was actually associated with distinctive PrPSc biochemical characteristics and if it was possible to univocally identify strains through PrPSc biochemical phenotypes. We selected six different vole-adapted strains (three human-derived and three animal-derived and analyzed PrPSc from individual voles by epitope mapping of protease resistant core of PrPSc (PrPres and by conformational stability and solubility assay. Overall, we discriminated five out of six prion strains, while two different scrapie strains showed identical PrPSc types. Our results suggest that the biochemical strain typing approach here proposed was highly discriminative, although by itself it did not allow us to identify all prion strains analyzed.

  7. Identification of pH tolerant Bradyrhizobium japonicum strains and ...

    African Journals Online (AJOL)

    Eight strains of Bradyrhizobium japonicum were isolated from the root nodules of soybean cultivar PK 472 collected from Adaptive Trial Centre, Bundi, India. All the isolates were authenticated through plant assay test in germination pouches. Growth of the isolated strains on different pH levels was observed and three strains ...

  8. [Bacillus subtilis and phenotypically similar strains producing hexaene antibiotics].

    Science.gov (United States)

    Kudriashova, E B; Vinokurova, N G; Ariskina, E V

    2005-01-01

    We studied metabolites synthesized by Bacillus subtilis strains, including the type strain of B. atrophaeus and phenotypically similar cultures. These metabolites were presented by polyene antibiotics with conjugated double bonds. Hexaenes from study strains inhibited the growth of phytopathogenic fungi Fusarium culmorum, F. sporotrichiella, F. oxysporum, Botrytis sorokiniana, Alternaria tenuis, and Phytophtora infestans. The degree of growth inhibition depended on the test fungus.

  9. Draft genome sequence of Agrobacterium rhizogenes strain NCPPB2659

    Science.gov (United States)

    This work reports the draft genome of Agrobacterium rhizogenes strain NCPPB2659 (also known as strain K599). The assembled genome contains 5,277,347 bp, and is composed of 1 circular chromosome, the Ri virulence plasmid, and 17 scaffolds pertaining to the linear chromosome. The wild type strain cau...

  10. Enrichment and isolation of microbial strains degrading bioplastic ...

    African Journals Online (AJOL)

    Polyvinyl alcohol (PVA) degrading bacterial strains were isolated from various environmental sites rich in plastic wastes by using the enrichment culture technique. Among the various isolated strains, the selected potent PVA degrading bacterial strains were tentatively characterized as Bacillus and Pseudomonas sp.

  11. Transversely loaded fiber optic grating strain sensors for aerospace applications

    Science.gov (United States)

    Udd, Eric; Schulz, Whitten L.; Seim, John M.; Trego, Angela; Haugse, Eric D.; Johnson, Patrick E.

    2000-05-01

    Most fiber grating sensor technology that has been developed to support strain sensing involves the measurement of axial strain. Fiber grating sensors are however capable of monitoring transverse as well as axial strain. This paper reviews a series of applications of this technology that are of particular interest to aerospace applications.

  12. Large strain cyclic behavior of metastable austenic stainless steel

    NARCIS (Netherlands)

    Geijselaers, Hubertus J.M.; Hilkhuijsen, P.; Bor, Teunis Cornelis; van den Boogaard, Antonius H.

    2015-01-01

    Metastable austenitic stainless steel will transform to martensite when subjected to mechanical working. In this research an austenitic stainless steel has been subjected to large amplitude strain paths containing a strain reversal. During the tests, apart from the stress and the strain also

  13. Draft Genome Sequence of Lactobacillus gasseri Strain 2016

    OpenAIRE

    Karlyshev, A. V.; V. G. Melnikov; Kosarev, I.V.; Khlebnikov, V.C.; Sukhikh, G T; Abramov, V.M.

    2013-01-01

    Different common factors contribute to the antagonistic properties of Lactobacillus gasseri toward various pathogens. However, there is strain-to-strain variation in the probiotic properties of this bacterium. The draft genome sequence of L. gasseri strain 2016 determined in this study will assist in understanding the genetic basis for such variation.

  14. Comparison of the adhesion ability of Candida albicans strains to ...

    African Journals Online (AJOL)

    Our results showed that oral C. albicans strains were able to adhere to epithelial cell lines and biomaterials with different degree. In fact, more than 61% of the tested strains were adhesive to Hep-2 and 83% to Caco-2 cells. Strong slime production after safranin stain was found in 40% of strains. Slime producer C. albicans ...

  15. Nociception and Conditioned Fear in Rats: Strains Matter

    NARCIS (Netherlands)

    Schaap, M.W.H.|info:eu-repo/dai/nl/314411488; van Oostrom, H.|info:eu-repo/dai/nl/340414634; Doornenbal, A.; van 't Klooster, J.; Baars, A.M.; Arndt, S.S.|info:eu-repo/dai/nl/30483615X; Hellebrekers, L.J.|info:eu-repo/dai/nl/073499234

    2013-01-01

    When using rats in pain research, strain-related differences in outcomes of tests for pain and nociception are acknowledged. However, very little is known about the specific characteristics of these strain differences. In this study four phylogenetically distant inbred rat strains, i.e. Wistar Kyoto

  16. Changes in job strain and subsequent weight gain

    DEFF Research Database (Denmark)

    Vesterlund, Gitte Kingo; Keller, Amélie Cléo; Heitmann, Berit Lilienthal

    2017-01-01

    Objective: Obesity as well as job strain is increasing, and job strain might contribute to weight gain. The objective of the current study was to examine associations between longitudinal alterations in the components of job strain and subsequent weight gain. Design: The study was designed...

  17. The Relationship of Coping Resources to Occupational Stress and Strain.

    Science.gov (United States)

    Osipow, Samuel H.; Davis, Anne S.

    1988-01-01

    Conducted a field study using the Osipow and Spokane (1983) scales to test the relationship of coping resources as moderators to stress-strain relationships. Found role overload to be the most significant source of strain but that coping resources contributed to moderating this and other stress-strain relationships. (Author/KS)

  18. Enrichment and isolation of microbial strains degrading bioplastic ...

    African Journals Online (AJOL)

    acer

    2015-07-08

    Jul 8, 2015 ... Polyvinyl alcohol (PVA) degrading bacterial strains were isolated from various environmental sites rich in plastic wastes by using the enrichment culture technique. Among the various isolated strains, the selected potent PVA degrading bacterial strains were tentatively characterized as Bacillus and.

  19. Measuring autogenous strain of concrete with corrugated moulds

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2008-01-01

    A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...

  20. strain partitioning and dimensional preferred orientation in a syn

    African Journals Online (AJOL)

    Administrator

    grain orientation. Calculated values of strain–arithmetic mean R, geometric mean G and harmonic mean H, show minimum strain for grains in E-W orientation and maximum strain for grains in N-S orientation. Phenocrysts in NE-SW and NW-SE orientations showed intermediate values of strain, with the latter axis having ...

  1. THE EFFECT OF DIFFERENT PROBIOTIC STRAINS ON FATTENINTHE EFFECT OF DIFFERENT PROBIOTIC STRAINS ON F

    Directory of Open Access Journals (Sweden)

    Cyril Hrnčár

    2013-02-01

    Full Text Available The aim of this work was to verify the effect of different probiotic strains applied through a drinking water source to fattening and carcass parameters of broiler ducks. Fattening experiment was realised in half-operating conditions of experimental basis of Department of Poultry Science and Small Animal Husbandry in three-floor cage technology. Totally 90 broiler duck were divided to three groups. Experimental group 1 (n=30 received probiotic strain Lactobacillus fermentum CCM 7158 with concentration of 1x109 colony forming units (CFU in drinking water daily addition of 0.90 g day 1 to day 56 of fattening. Experimental group 2 (n=30 received probiotic strain Enterococcus faecium M 74 with concentration of 1x109 colony forming units (CFU in drinking water daily addition of 0.45 g day 1 to day 56 of fattening. The control group of birds (n=30 received water without any probiotics. The supplementation of probiotic strains Lactobacillus fermentum and Enterococcus faecium no significant affected (P≥0.05 final body weight, feed consumption and mortality of broiler ducks. From carcass parameters, we recorded statistically significant (P<0.05 reduction in weight of abdominal fat of broiler ducks for application of tested probiotic strains.

  2. Mismatching between circulating strains and vaccine strains of influenza: Effect on Hajj pilgrims from both hemispheres.

    Science.gov (United States)

    Alfelali, Mohammad; Khandaker, Gulam; Booy, Robert; Rashid, Harunor

    2016-03-03

    The trivalent seasonal influenza vaccine is expected to provide optimum protection if the vaccine strains match the circulating strains. The effect of worldwide mismatch between the vaccine strains and extant strains on travelers attending Hajj pilgrimage is not known. Annually 2-3 million Muslims coming from north and south hemispheres congregate at Hajj in Mecca, Saudi Arabia, where intense congestion amplifies the risk of respiratory infection up to eight fold. In order to estimate, to what extent mismatching increases the risk of vaccine failure in Hajj pilgrims, we have examined the global data on influenza epidemiology since 2003, in light of the available data from Hajj. These data demonstrate that globally mismatching between circulating and vaccine strains has occurred frequently over the last 12 years, and the mismatch seems to have affected the Hajj pilgrims, however, influenza virus characteristics were studied only in a limited number of Hajj seasons. When the vaccines are different, dual vaccination of travelers by vaccines for southern and northern hemispheres should be considered for Hajj pilgrims whenever logistically feasible. Consideration should also be given to the use of vaccines with broader coverage, i.e., quadrivalent, or higher immunogenicity. Continuous surveillance of influenza at Hajj is important.

  3. Early detection of left ventricular dysfunction in asymptomatic diabetic patient using strain and strain rate echocardiographic imaging

    Directory of Open Access Journals (Sweden)

    Rania Gaber

    2014-03-01

    Conclusion: Type 2 diabetes mellitus deteriorate both LV systolic and diastolic performance. Strain and strain rate by tissue Doppler Imaging is superior to conventional Doppler in early detection and evaluation of systolic and diastolic dysfunction in type 2 diabetic patients.

  4. Radial and longitudinal strain and strain rate assessed by speckle-tracking echocardiography in dogs with myxomatous mitral valve disease

    DEFF Research Database (Denmark)

    Zois, Nora Elisabeth; Tidholm, A.; Nägga, K.M.

    2012-01-01

    Assessment of left ventricular (LV) function using conventional echocardiographic methods is difficult in mitral regurgitation (MR) owing to altered hemodynamic loading conditions. Newer methods such as speckle-tracking echocardiography (STE) provide assessment of LV strain (St) and strain rates ...

  5. [Comparison of genotype characteristics between the circulating mumps virus strain in Beijing area and the vaccine strain].

    Science.gov (United States)

    Chen, Meng; Zhang, Tie-gang; Chen, Li-juan; Wu, Jiang; Yang, Jie; Zhang, Wei

    2009-11-01

    To compare the genetic characteristics of mumps virus strain circulating in Beijing with vaccine strain and to preliminarily analysis the reasons of vaccine ineffectiveness. The following methods were used: Isolation and identification of the mumps virus which had been circulating in Beijing, immunization history analysis, SH gene sequence analysis and comparison genotype homology with reference strains and analysis of the key amino acid sites of HN variation. In 38 mumps cases that virus had been isolated from, another seven cases were IgM negative. In 2007 and 2008, the positive rates on virus isolation, RT-PCR and IgM-decreased significantly, while the cases with immunization history had an increase. Cases without histories of vaccination had both higher positive rates on virus isolation and IgM. Thirty-eight strains belonged to F genotype virus, but vaccine strain was A genotype. The circulating viruses showed 5.6% sequence divergence on SH gene nucleotide and 16.0% - 18.1% from vaccine strain. Conservative hydrophobic amino acids on SH protein of some Beijing strains had changed. For example, there were 6 strains, from No.8: L-->F. The circulating viruses showed 2.3% sequence divergence on HN protein amino acid sequences and 4.2% - 5.3% from vaccine strain. Amino acids sites, which deciding the ability of cross-neutralization of the Beijing strains and vaccine strains were different. At the 354 and 356 sites, all the Beijing strains were different from the vaccine strains. The N-glycosylation sites on HN of Beijing strains were also different from those on vaccine strains. Locations 464 - 466 appeared to be NCS on Beijing strain, but locations 464 - 466 were NCR on the vaccine strains. Another 18 unknown function amino acids sites of all Beijing strains were different from those on vaccine strains. In recent years, genotype F became the main genotype of circulating strains in Beijing without genotype variation, but larger difference was found between them

  6. High-Strain, High-Strain-Rate Deformation Behavior of Tantalum and Tantalum-Tungsten Based Alloys

    OpenAIRE

    Marquis, F; Chen, Y.; Chen, Y.

    1997-01-01

    The microstructural evolution in high-strain, high-strain-rate deformation of annealed tantalum and tantalum-tungsten alloys with 1 and 2.5 wt.% and the occurrence of shear localization has been investigated. The microstructure generated at high strain rates progresses from highly dislocated grains, to lath cells, to subgrains, and finally to small grains as the shear strain increases. The temperature rise predictions from the constitutive equations which describe the materials behavior indic...

  7. Body fat distribution and organ weights of 14 common strains and a 22-strain consomic panel of rats

    OpenAIRE

    Reed, Danielle R.; Duke, Fujiko F.; Ellis, Hillary K.; Rosazza, Matthew R.; Lawler, Maureen P.; Alarcon, Laura K.; Tordoff, Michael G.

    2011-01-01

    The goal of this study was to determine the adiposity of a range of rat strains including a panel of consomics to estimate the heritability of fatness as measured by necropsy. To that end, we assessed the body fat distribution and organ weights of groups of adult male rats from 3 outbred strains, 11 inbred strains and 22 consomic strains. We measured the weights of the gonadal, retroperitoneal, mesenteric, femoral, subscapular and pericardial white fat depots, the subscapular brown fat depot,...

  8. Selective enrichment media bias the types of Salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths.

    Science.gov (United States)

    Gorski, Lisa

    2012-01-01

    For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the pathogen the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown in one set of standard enrichment media to see if culture bias patterns emerged. Nineteen strains representing four serogroups and ten serotypes were compared in four-strain mixtures in Salmonella-only and in cattle fecal culture enrichment backgrounds using Salmonella enrichment media. One or more strain(s) emerged as dominant in each mixture. No serotype was most fit, but strains of serogroups C2 and E were more likely to dominate enrichment culture mixtures than strains of serogroups B or C1. Different versions of Rappaport-Vassiliadis (RV) medium gave different patterns of strain dominance in both Salmonella-only and fecal enrichment culture backgrounds. The fittest strains belonged to serogroups C1, C2, and E, and included strains of S. Infantis, S. Thompson S. Newport, S. 6,8:d:-, and S. Give. Strains of serogroup B, which included serotypes often seen in outbreaks such as S. Typhimurium, S. Saintpaul, and S. Schwarzengrund were less likely to emerge as dominant strains in the mixtures when using standard RV as part of the enrichment. Using a more nutrient-rich version of RV as part of the protocol led to a different pattern of strains emerging, however some were still present in very low numbers in the resulting population. These results indicate that outbreak investigations of food and/or other environmental samples should include multiple enrichment protocols to ensure isolation of target strains of Salmonella.

  9. Revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus CGMCC 2955.

    Directory of Open Access Journals (Sweden)

    Cheng Zhong

    Full Text Available A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955 using DEC (diethyl sulfate and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA cycle was obtained in mutant strain (57.0% compared with parent strain (17.0%. It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH, which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53-6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.

  10. Kinases of two strains of Mycoplasma hyopneumoniae and a strain of Mycoplasma synoviae: an overview

    Directory of Open Access Journals (Sweden)

    Alexandre Melo Bailão

    2007-01-01

    Full Text Available Mycoplasma synoviae and Mycoplasma hyopneumoniae are wall-less eubacteria belonging to the class of Mollicutes. These prokaryotes have a reduced genome size and reduced biosynthetic machinery. They cause great losses in animal production. M. synoviae is responsible for an upper respiratory tract disease of chickens and turkeys. M. hyopneumoniae is the causative agent of enzootic pneumonia in pigs. The complete genomes of these organisms showed 17 ORFs encoding kinases in M. synoviae and 15 in each of the M. hyopneumoniae strain. Four kinase genes were restricted to the avian pathogen while three were specific to the pig pathogen when compared to each other. All deduced kinases found in the non pathogenic strain (J[ATCC25934] were also found in the pathogenic M. hyopneumoniae strain. The enzymes were classified in nine families composing five fold groups.

  11. Low-cycle fatigue behavior of 316 stainless steel at FBR temperature. Effects of strain rate and strain wave form

    Energy Technology Data Exchange (ETDEWEB)

    Nonaka, Isamu; Kitagawa, Masaki; Ohtomo, Akira (Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan))

    1983-07-01

    The effects of strain rate and strain wave form on the low-cycle fatigue behavior of 316 stainless steel at FBR temperature were studied in order to clarify the controlling factor of fatigue strength and fracture mechanism. The following major results are obtained. (1) Under symmetrical and asymmetrical straining (slow-fast and fast-slow wave) with the strain rate between 10/sup 0/%/sec to 10/sup -3/%/sec, the fatigue life decreases with a decrease of strain rate in tension going period. The fatigue life is affected only by the strain rate in tension going period, and is not affected by the strain rate in compression going period. Slow-fast wave is most damaging, but the effect of saw-tooth wave is not significant. (2) The dependence of fatigue life on the strain rate in tension going period may not be due to the creep effect but due to the dynamic strain aging effect proper to FBR temperature (500/sup 0/C to 600/sup 0/C) (3) The fracture mode changes from transgranular cracking to intergranular cracking with a decrease of strain rate in tension going period. Slow-fast wave enhances the intergranular cracking, whereas fast-slow wave enhances the transgranular cracking. (4) Thermal aging increases the fatigue life under symmetrical and asymmetrical straining, and the life reduction with the strain rate reduction in tension going period is not so significant for the thermally aged condition.

  12. Complete Genome Sequences of Bovine Parainfluenza Virus Type 3 Strain BN-1 and Vaccine Strain BN-CE.

    Science.gov (United States)

    Ohkura, Takashi; Kokuho, Takehiro; Konishi, Misako; Kameyama, Ken-Ichiro; Takeuchi, Kaoru

    2013-01-01

    Bovine parainfluenza virus type 3 (BPIV3) is associated with upper respiratory disease in cattle in many countries. Here, we report the complete genome sequences of the BPIV3 BN-1 strain, isolated from cattle in Japan, and the BN-CE vaccine strain, derived from the BN-1 strain by passages in chicken embryo fibroblasts.

  13. Sequential acquisition of Potato virus Y strains by Myzus persicae favors the transmission of the emerging recombinant strains

    Science.gov (United States)

    In the past decade recombinant strains of potato virus Y (PVY) have overtaken the ordinary strain, PVYO, as the predominant viruses affecting the US seed potato crop. Aphids may be a contributing factor in the emergence of the recombinant strains, but studies indicate that differences in transmissio...

  14. Repeated Strains, Social Control, Social Learning, and Delinquency: Testing an Integrated Model of General Strain Theory in China

    Science.gov (United States)

    Bao, Wan-Ning; Haas, Ain; Chen, Xiaojin; Pi, Yijun

    2014-01-01

    In Agnew's general strain theory, repeated strains can generate crime and delinquency by reducing social control and fostering social learning of crime. Using a sample of 615 middle-and high-school students in China, this study examines how social control and social learning variables mediate the effect of repeated strains in school and at home on…

  15. A Comprehensive Test of General Strain Theory: Key Strains, Situational- and Trait-Based Negative Emotions, Conditioning Factors, and Delinquency

    Science.gov (United States)

    Moon, Byongook; Morash, Merry; McCluskey, Cynthia Perez; Hwang, Hye-Won

    2009-01-01

    Using longitudinal data on South Korean youth, the authors addressed limitations of previous tests of general strain theory (GST), focusing on the relationships among key strains, situational- and trait-based negative emotions, conditioning factors, and delinquency. Eight types of strain previously shown most likely to result in delinquency,…

  16. Examining the Links between Strain, Situational and Dispositional Anger, and Crime: Further Specifying and Testing General Strain Theory.

    Science.gov (United States)

    Mazerolle, Paul; Piquero, Alex R.; Capowich, George E.

    2003-01-01

    Explored whether relationships between strain, anger, and deviant outcomes varied when using trait- or situational-based measures of anger, noting whether people with higher trait anger had increased likelihood of experiencing strain, becoming angry from strain, and responding deviantly. Relying on trait-based static indicators of anger was…

  17. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Science.gov (United States)

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water.

  18. Forming limit strains for non-linear strain path of AA6014 aluminium sheet deformed at room temperature

    Science.gov (United States)

    Bressan, José Divo; Liewald, Mathias; Drotleff, Klaus

    2017-10-01

    Forming limit strain curves of conventional aluminium alloy AA6014 sheets after loading with non-linear strain paths are presented and compared with D-Bressan macroscopic model of sheet metal rupture by critical shear stress criterion. AA6014 exhibits good formability at room temperature and, thus, is mainly employed in car body external parts by manufacturing at room temperature. According to Weber et al., experimental bi-linear strain paths were carried out in specimens with 1mm thickness by pre-stretching in uniaxial and biaxial directions up to 5%, 10% and 20% strain levels before performing Nakajima testing experiments to obtain the forming limit strain curves, FLCs. In addition, FLCs of AA6014 were predicted by employing D-Bressan critical shear stress criterion for bi-linear strain path and comparisons with the experimental FLCs were analyzed and discussed. In order to obtain the material coefficients of plastic anisotropy, strain and strain rate hardening behavior and calibrate the D-Bressan model, tensile tests, two different strain rate on specimens cut at 0°, 45° and 90° to the rolling direction and also bulge test were carried out at room temperature. The correlation of experimental bi-linear strain path FLCs is reasonably good with the predicted limit strains from D-Bressan model, assuming equivalent pre-strain calculated by Hill 1979 yield criterion.

  19. Strain and strain rate by two-dimensional speckle tracking echocardiography in a maned wolf

    Directory of Open Access Journals (Sweden)

    Matheus M. Mantovani

    2012-12-01

    Full Text Available The measurement of cardiovascular features of wild animals is important, as is the measurement in pets, for the assessment of myocardial function and the early detection of cardiac abnormalities, which could progress to heart failure. Speckle tracking echocardiography (2D STE is a new tool that has been used in veterinary medicine, which demonstrates several advantages, such as angle independence and the possibility to provide the early diagnosis of myocardial alterations. The aim of this study was to evaluate the left myocardial function in a maned wolf by 2D STE. Thus, the longitudinal, circumferential and radial strain and strain rate were obtained, as well as, the radial and longitudinal velocity and displacement values, from the right parasternal long axis four-chamber view, the left parasternal apical four chamber view and the parasternal short axis at the level of the papillary muscles. The results of the longitudinal variables were -13.52±7.88, -1.60±1.05, 4.34±2.52 and 3.86±3.04 for strain (%, strain rate (1/s, displacement (mm and velocity (cm/s, respectively. In addition, the radial and circumferential Strain and Strain rate were 24.39±14.23, 1.86±0.95 and -13.69±6.53, -1.01±0.48, respectively. Thus, the present study provides the first data regarding the use of this tool in maned wolves, allowing a more complete quantification of myocardial function in this species.

  20. Improved Hardware for Higher Spatial Resolution Strain-ENCoded (SENC) Breast MRI for Strain Measurements

    Science.gov (United States)

    Harouni, Ahmed A.; Hossain, Jakir; Jacobs, Michael A.; Osman, Nael F.

    2012-01-01

    Introduction Early detection of breast lesions using mammography has resulted in lower mortality-rates. However, some breast lesions are mammography occult and magnetic resonance imaging (MRI) is recommended, but has lower specificity. It is possible to achieve higher specificity by using Strain-ENCoded (SENC) MRI and/or magnetic resonance elastography(MRE). SENC breast MRI can measure the strain properties of breast tissue. Similarly, MRE is used to measure elasticity (i.e., shear stiffness) of different tissue compositions interrogating the tissue mechanical properties. Reports have shown that malignant tumors are 3–13 times stiffer than normal tissue and benign tumors. Methods We have developed a Strain-ENCoded (SENC) breast hardware device capable of periodically compressing the breast, thus allowing for longer scanning time and measuring the strain characteristics of breast tissue. This hardware enabled us to use SENC MRI with high spatial resolution (1×1×5mm3) instead of Fast SENC(FSENC). Simple controls and multiple safety measures were added to ensure accurate, repeatable and safe in-vivo experiments. Results Phantom experiments showed that SENC breast MRI has higher SNR and CNR than FSENC under different scanning resolutions. Finally, the SENC breast device reproducibility measurements resulted in a difference of less than one mm with a 1% strain difference. Conclusion SENC breast MR images have higher SNR and CNR than FSENC images. Thus, combining SENC breast strain measurements with diagnostic breast MRI to differentiate benign from malignant lesions could potentially increase the specificity of diagnosis in the clinical setting. PMID:21440464

  1. Hydrogen production by recombinant Escherichia coli strains

    Science.gov (United States)

    Maeda, Toshinari; Sanchez‐Torres, Viviana; Wood, Thomas K.

    2012-01-01

    Summary The production of hydrogen via microbial biotechnology is an active field of research. Given its ease of manipulation, the best‐studied bacterium Escherichia coli has become a workhorse for enhanced hydrogen production through metabolic engineering, heterologous gene expression, adaptive evolution, and protein engineering. Herein, the utility of E. coli strains to produce hydrogen, via native hydrogenases or heterologous ones, is reviewed. In addition, potential strategies for increasing hydrogen production are outlined and whole‐cell systems and cell‐free systems are compared. PMID:21895995

  2. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    2012-01-01

    The effective stress coefficient, introduced by Biot, is used for predicting effective stress or pore pressure in the subsurface. It is not a constant value. It is different for different types of sediment and it is stress dependent. We used a model, based on contact between the grains to describe...... one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective stress...... determined under uniaxial strain condition will be more relevant in reservoir studies....

  3. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

    Alam, M.M.; Fabricius, I.L.

    2012-01-01

    The effective stress coefficient, introduced by Biot, is used for predicting effective stress or pore pressure in the subsurface. It is not a constant value. It is different for different types of sediment and it is stress dependent. We used a model, based on contact between the grains to describe...... one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective stress...... determined under uniaxial strain condition will be more relevant in reservoir studies. Copyright 2012 ARMA, American Rock Mechanics Association....

  4. Quantum Chemical Strain Analysis For Mechanochemical Processes.

    Science.gov (United States)

    Stauch, Tim; Dreuw, Andreas

    2017-04-18

    The use of mechanical force to initiate a chemical reaction is an efficient alternative to the conventional sources of activation energy, i.e., heat, light, and electricity. Applications of mechanochemistry in academic and industrial laboratories are diverse, ranging from chemical syntheses in ball mills and ultrasound baths to direct activation of covalent bonds using an atomic force microscope. The vectorial nature of force is advantageous because specific covalent bonds can be preconditioned for rupture by selective stretching. However, the influence of mechanical force on single molecules is still not understood at a fundamental level, which limits the applicability of mechanochemistry. As a result, many chemists still resort to rules of thumb when it comes to conducting mechanochemical syntheses. In this Account, we show that comprehension of mechanochemistry at the molecular level can be tremendously advanced by quantum chemistry, in particular by using quantum chemical force analysis tools. One such tool is the JEDI (Judgement of Energy DIstribution) analysis, which provides a convenient approach to analyze the distribution of strain energy in a mechanically deformed molecule. Based on the harmonic approximation, the strain energy contribution is calculated for each bond length, bond angle and dihedral angle, thus providing a comprehensive picture of how force affects molecules. This Account examines the theoretical foundations of quantum chemical force analysis and provides a critical overview of the performance of the JEDI analysis in various mechanochemical applications. We explain in detail how this analysis tool is to be used to identify the "force-bearing scaffold" of a distorted molecule, which allows both the rationalization and the optimization of diverse mechanochemical processes. More precisely, we show that the inclusion of every bond, bending and torsion of a molecule allows a particularly insightful discussion of the distribution of mechanical

  5. [Carbohydrate assimilation by clinical and environmental Rhodotorula glutinis strains].

    Science.gov (United States)

    García-Martos, Pedro; García-Agudo, Lidia; Ruiz-Aragón, Jesús; Saldarreaga, Abel; Marín, Pilar

    2004-06-01

    This study was carried to determine the carbohydrate assimilation patterns of Rhodotorula strains isolated from clinical and environmental specimens. We have tested the commercial system ID 32C (bioMerieux, France) on 80 different strains of Rhodotorula glutinis: 47 strains from clinical samples and 33 strains from environmental samples. The assimilation percentages obtained in our study for galactose, cellobiose, gluconate and sorbose were lower than those showed in the identification table of the method. However, the assimilation percentages for mannitol and esculin were higher. According to our results, we conclude that the numerical profiles and the identification software of the commercial system present limitations for the characterization of some R. glutinis strains.

  6. Dermatophilus congolensis: strain differences in expression of phospholipase activities.

    Science.gov (United States)

    Masters, A M; Ellis, T M; Grein, S B

    1997-09-01

    Interactions between Dermatophilus congolensis strains and with other bacteria of known haemolytic activities were used to elucidate the complex nature of haemolytic activities present in various D. congolensis strains. This was further analysed by measuring their specific phospholipase activities against defined substrates by thin layer chromatography. D. congolensis strains demonstrated haemolytic interactions (synergistic or antagonistic) with other D. congolensis strains and also other species of bacteria. Most isolates expressed lyso-phospholipase-D activity, while various strains also expressed sphingomyelinase-D activity, phospholipase-A versus phosphatidylcholines and/or cephalins, phospholipase-D versus phosphatidylcholines or all these activities, under the culture conditions used.

  7. Piezoelectric effect in non-uniform strained carbon nanotubes

    Science.gov (United States)

    Ilina, M. V.; Blinov, Yu F.; Ilin, O. I.; Rudyk, N. N.; Ageev, O. A.

    2017-10-01

    The piezoelectric effect in non-uniform strained carbon nanotubes (CNTs) has been studied. It is shown that the magnitude of strained CNTs surface potential depends on a strain value. It is established that the resistance of CNT also depends on the strain and internal electric field, which leads to the hysteresis in the current-voltage characteristics. Analysis of experimental studies of the non-uniform strained CNT with a diameter of 92 nm and a height of 2.1 μm allowed us to estimate the piezoelectric coefficient 0.107 ± 0.032 C/m2.

  8. The effect of strain rate on the viscoplastic behavior of isotactic polypropylene at finite strains

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville

    2002-01-01

    stresses (which is observed as strain-hardening of specimens in the post-yield regions of deformations) elastic moduli are assumed to depend on the principal invariants of the right Cauchy–Green tensor for the viscoplastic flow. Stress–strain relations for a semicrystalline polymer are derived by using...... the laws of thermodynamics. The constitutive equations are determined by five adjustable parameters that are found by matching observations. Fair agreement is demonstrated between the experimental data and the results of numerical simulation. A noticeable difference is revealed between the mechanical...

  9. The genome of Shigella dysenteriae strain Sd1617 comparison to representative strains in evaluating pathogenesis.

    Science.gov (United States)

    Vongsawan, Ajchara A; Kapatral, Vinayak; Vaisvil, Benjamin; Burd, Henry; Serichantalergs, Oralak; Venkatesan, Malabi M; Mason, Carl J

    2015-03-01

    We sequenced and analyzed Shigella dysenteriae strain Sd1617 serotype 1 that is widely used as model strain for vaccine design, trials and research. A combination of next-generation sequencing platforms and assembly yielded two contigs representing a chromosome size of 4.34 Mb and the large virulence plasmid of 177 kb. This genome sequence is compared with other Shigella genomes in order to understand gene complexity and pathogenic factors. © The Author 2015. Published by Oxford University Press on behalf of on behalf of Federation of European Microbiological Society.

  10. Genome Sequence of Campylobacter jejuni strain 327, a strain isolated from a turkey slaughterhouse

    DEFF Research Database (Denmark)

    Takamiya, Monica; Özen, Asli Ismihan; Rasmussen, Morten

    2011-01-01

    , catalase positive bacterium obtains energy from the metabolism of amino acids and Krebs cycle intermediates. Strain 327 was isolated from a turkey slaughter production line and is considered environmentally sensitive to food processing (cold, heat, drying) and storage conditions. The 327 whole genome...... shotgun sequence of 1,618,613 bp long consists of 1,740 protein-coding genes, 46 tRNA genes and 3 rRNA operons. A protein based BLAST analysis places the turkey isolate 327 close to the human clinical strain 81116 (NCTC 11828)....

  11. High spatial resolution distributed optical fiber dynamic strain sensor with enhanced frequency and strain resolution.

    Science.gov (United States)

    Masoudi, Ali; Newson, Trevor P

    2017-01-15

    A distributed optical fiber dynamic strain sensor with high spatial and frequency resolution is demonstrated. The sensor, which uses the ϕ-OTDR interrogation technique, exhibited a higher sensitivity thanks to an improved optical arrangement and a new signal processing procedure. The proposed sensing system is capable of fully quantifying multiple dynamic perturbations along a 5 km long sensing fiber with a frequency and spatial resolution of 5 Hz and 50 cm, respectively. The strain resolution of the sensor was measured to be 40 nε.

  12. Clinical strains of acinetobacter classified by DNA-DNA hybridization

    Energy Technology Data Exchange (ETDEWEB)

    Tjernberg, I.; Ursing, J. (Department of Medical Microbiology, University of Lund, Malmoe General Hospital, Malmoe (Sweden))

    1989-01-01

    A collection of Acinetobacter strains consisting of 168 consecutive clinical strains and 30 type and reference strains was studied by DNA-DNA hybridization and a few phenotypic tests. The field strains could be allotted to 13 DNA groups. By means of reference strains ten of these could be identified with groups described by Bouvet and Grimont (1986), while three groups were new; they were given the numbers 13-15. The type strain of A. radioresistens- recently described by Nishimura et al. (1988) - was shown to be a member of DNA group 12, which comprised 31 clinical isolates. Of the 19 strains of A. junii, eight showed hemolytic acitivity on sheep and human blood agar and an additional four strains on human blood agar only. Strains of this species have previously been regarded as non-hemolytic. Reciprocal DNA pairing data for the reference strains of the DNA gropus were treated by UPGMA clustering. The reference strains for A. calcoaceticus, A. baumannii and DNA groups 3 and 13 formed a cluster with about 70% relatedness within the cluster. Other DNA groups joined at levels below 60%. (author).

  13. Strain-Dependent Norovirus Bioaccumulation in Oysters ▿

    Science.gov (United States)

    Maalouf, Haifa; Schaeffer, Julien; Parnaudeau, Sylvain; Le Pendu, Jacques; Atmar, Robert L.; Crawford, Sue E.; Le Guyader, Françoise S.

    2011-01-01

    Noroviruses (NoVs) are the main agents of gastroenteritis in humans and the primary pathogens of shellfish-related outbreaks. Some NoV strains bind to shellfish tissues by using carbohydrate structures similar to their human ligands, leading to the hypothesis that such ligands may influence bioaccumulation. This study compares the bioaccumulation efficiencies and tissue distributions in oysters (Crassostrea gigas) of three strains from the two principal human norovirus genogroups. Clear differences between strains were observed. The GI.1 strain was the most efficiently concentrated strain. Bioaccumulation specifically occurred in digestive tissues in a dose-dependent manner, and its efficiency paralleled ligand expression, which was highest during the cold months. In comparison, the GII.4 strain was very poorly bioaccumulated and was recovered in almost all tissues without seasonal influence. The GII.3 strain presented an intermediate behavior, without seasonal effect and with less bioaccumulation efficiency than that of the GI.1 strain during the cold months. In addition, the GII.3 strain was transiently concentrated in gills and mantle before being almost specifically accumulated in digestive tissues. Carbohydrate ligand specificities of the strains at least partly explain the strain-dependent bioaccumulation characteristics. In particular, binding to the digestive-tube-specific ligand should contribute to bioaccumulation, whereas we hypothesize that binding to the sialic acid-containing ligand present in all tissues would contribute to retain virus particles in the gills or mantle and lead to rapid destruction. PMID:21441327

  14. [Xylanase activity of phytopathogenic and endophytic strains of Ceratocystis sp].

    Science.gov (United States)

    Kurchenko, I M; Sokolova, O V; Iur'ieva, O M

    2010-01-01

    A comparative analysis of xylanase activity of 36 phytopathogenic and endophytic Ceratocystis sp. strains was conducted. The rate of their linear growth on the medium with xylan was studied. The rate of linear growth of phytopathogenic strains was 0.003-0.004 mm/h that was almost 70 times less than in endophytic ones. There were no correlation between levels of xylanase activity of studied strains and rates of their linear growth. Xylanase activity ofendophytic Ceratocystis sp. strains varied from complete absence to high level. Phytopathogenic strains possessed only high xylanase activity; maximum values of their xylanase activity zones were three times more than in endophytic strains. The differences in xylanase activity were observed on the strain level. The xylanase activity of 24% endophytic and 64% phytopathogenic strains became higher with increasing of cultivation period. The clear dependence of xylanase activity on the species and organs of host plants was not demonstrated. It was shown that the xylanase activity level of phytopathogenic Ceratocystis sp. strains was too much higher than in such phytopathogens as Fusarium poae, F. oxysporum and Alternaria alternata strains. The conclusion was made that the studied endophytic Ceratocystis sp. strains can be related to latent pathogens, which are able to cause the diseases of host plants in conditions favorable for them.

  15. FLO gene-dependent phenotypes in industrial wine yeast strains.

    Science.gov (United States)

    Govender, Patrick; Bester, Michael; Bauer, Florian F

    2010-04-01

    Most commercial yeast strains are nonflocculent. However, controlled flocculation phenotypes could provide significant benefits to many fermentation-based industries. In nonflocculent laboratory strains, it has been demonstrated that it is possible to adjust flocculation and adhesion phenotypes to desired specifications by altering expression of the otherwise silent but dominant flocculation (FLO) genes. However, FLO genes are characterized by high allele heterogeneity and are subjected to epigenetic regulation. Extrapolation of data obtained in laboratory strains to industrial strains may therefore not always be applicable. Here, we assess the adhesion phenotypes that are associated with the expression of a chromosomal copy of the FLO1, FLO5, or FLO11 open reading frame in two nonflocculent commercial wine yeast strains, BM45 and VIN13. The chromosomal promoters of these genes were replaced with stationary phase-inducible promoters of the HSP30 and ADH2 genes. Under standard laboratory and wine making conditions, the strategy resulted in expected and stable expression patterns of these genes in both strains. However, the specific impact of the expression of individual FLO genes showed significant differences between the two wine strains and with corresponding phenotypes in laboratory strains. The data suggest that optimization of the flocculation pattern of individual commercial strains will have to be based on a strain-by-strain approach.

  16. Strain engineering on transmission carriers of monolayer phosphorene

    Science.gov (United States)

    Zhang, Wei; Li, Feng; Hu, Junsong; Zhang, Ping; Yin, Jiuren; Tang, Xianqiong; Jiang, Yong; Wu, Bozhao; Ding, Yanhuai

    2017-11-01

    The effects of uniaxial strain on the structure, band gap and transmission carriers of monolayer phosphorene were investigated by first-principles calculations. The strain induced semiconductor-metal as well as direct–indirect transitions were studied in monolayer phosphorene. The position of CBM which belonged to indirect gap shifts along the direction of the applied strain. We have concluded the change rules of the carrier effective mass when plane strains are applied. In band structure, the sudden decrease of band gap or the new formation of CBM (VBM) causes the unexpected change in carrier effective mass. The effects of zigzag and armchair strain on the effective electron mass in phosphorene are different. The strain along zigzag direction has effects on the electrons effective mass along both zigzag and armchair direction. By contrast, armchair-direction strain seems to affect only on the free electron mass along zigzag direction. For the holes, the effective masses along zigzag direction are largely affected by plane strains while the effective mass along armchair direction exhibits independence in strain processing. The carrier density of monolayer phosphorene at 300 K is calculated about 1.25× {{10}6} cm‑2, which is greatly influenced by the temperature and strain. Strain engineering is an efficient method to improve the carrier density in phosphorene.

  17. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  18. Tuning Surface Properties of Low Dimensional Materials via Strain Engineering.

    Science.gov (United States)

    Yang, Shengchun; Liu, Fuzhu; Wu, Chao; Yang, Sen

    2016-08-01

    The promising and versatile applications of low dimensional materials are largely due to their surface properties, which along with their underlying electronic structures have been well studied. However, these materials may not be directly useful for applications requiring properties other than their natal ones. In recent years, strain has been shown to be an additionally useful handle to tune the physical and chemical properties of materials by changing their geometric and electronic structures. The strategies for producing strain are summarized. Then, the electronic structure of quasi-two dimensional layered non-metallic materials (e.g., graphene, MX2, BP, Ge nanosheets) under strain are discussed. Later, the strain effects on catalytic properties of metal-catalyst loaded with strain are focused on. Both experimental and computational perspectives for dealing with strained systems are covered. Finally, an outlook on engineering surface properties utilizing strain is provided. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Mechanical Behavior of 316L Stainless Steel after Strain Hardening

    Directory of Open Access Journals (Sweden)

    Li Kaishang

    2017-01-01

    Full Text Available The effects of strain hardening on the mechanical behavior of 316L stainless steel were studied in the paper. The original and different strain hardening materials were compared to investigate the mechanical behavior. The results demonstrate that the yield strengths increase with the magnitude of strain hardening significantly, but the ultimate strengths of the original and different strain hardening materials are closed. In addition, the plastic parameters of 316L stainless steel including fracture elongation and fracture surface shrinkage decrease with the magnitude of strain hardening. Finally, the Ramberg-Osgood equation is used to predict the stress-strain curves after strain hardening, and the results indicate that the predicted values agree with the experimental values.

  20. Tensile stress-strain behavior of boron/aluminum laminates

    Science.gov (United States)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  1. Strain engineering on thermoelectric performance of Mg2Si

    Science.gov (United States)

    Kaur, Kulwinder; Dhiman, Shobhna; Kumar, Ranjan

    2017-07-01

    In this work, we propose to boost the thermoelectric performance of bulk magnesium silicide using isotropic strain. The effect of strain on the electronic and thermoelectric properties of Mg2Si is analyzed using first principles calculations combined with semi-classical Boltzmann theory. The Seebeck coefficient, power factor and electrical conductivity are strongly modified with strain. The lattice thermal conductivity is also tuned with strain. However, the strain effect on the lattice thermal conductivity of Mg2Si has not yet been systematically studied. The effect of strain on lattice thermal conductivity, specific heat, phonon dispersion curves and phonon density of states of Mg2Si are studied for the first time in this paper. The lattice thermal conductivity of bulk Mg2Si is shown to decrease continuously when applied strain changes from compressive to tensile. The results obtained in this paper have great importance in the thermoelectric field.

  2. Selection of strains for shiitake production in axenic substrate.

    Science.gov (United States)

    Zied, Diego Cunha; Maciel, William Pereira; Marques, Simone Cristina; da Silveira E Santos, Débora Marques; Rinker, Danny Lee; Dias, Eustáquio Souza

    2016-10-01

    Shiitake mushroom consumption is increasing in Brazil. In addition to the implementation of new production methods, it is also important to increase productivity, quality and reduce production costs. In this study, six commercial Lentinula edodes strains were characterized for genetic diversity (rep-PCR analysis) and mushroom production (yield, number and weight of individual mushrooms) using different substrates and cultural conditions. All strains showed genetic differences by repetitive element palindromic based-polymerase chain reaction (rep-PCR). The richest substrate resulted in the greatest production under both environmental conditions. Strains LE4 and LE6 produced the majority of their mushrooms earlier than the other strains. The highest number of mushrooms was observed in the LE6 strain while the highest weights of individual mushrooms were observed in the LE4 strain. Controlled environmental conditions resulted in superior production for all strains, except for LE4, which had empirically greater yield in the semi-controlled environmental condition.

  3. FTIR spectroscopic discrimination of Saccharomyces cerevisiae and Saccharomyces bayanus strains.

    Science.gov (United States)

    Adt, Isabelle; Kohler, Achim; Gognies, Sabine; Budin, Julien; Sandt, Christophe; Belarbi, Abdelkader; Manfait, Michel; Sockalingum, Ganesh D

    2010-09-01

    In this study, we tested the potential of Fourier-transform infrared absorption spectroscopy to screen, on the one hand, Saccharomyces cerevisiae and non-S. cerevisiae strains and, on the other hand, to discriminate between S. cerevisiae and Saccharomyces bayanus strains. Principal components analysis (PCA), used to compare 20 S. cerevisiae and 21 non-Saccharomyces strains, showed only 2 misclassifications. The PCA model was then used to classify spectra from 14 Samos strains. All 14 Samos strains clustered together with the S. cerevisiae group. This result was confirmed by a routinely used electrophoretic pattern obtained by pulsed-field gel electrophoresis. The method was then tested to compare S. cerevisiae and S. bayanus strains. Our results indicate that identification at the strain level is possible. This first result shows that yeast classification and S. bayanus identification can be feasible in a single measurement.

  4. Fermentation characteristics of Dekkera bruxellensis strains.

    Science.gov (United States)

    Blomqvist, Johanna; Eberhard, Thomas; Schnürer, Johan; Passoth, Volkmar

    2010-07-01

    The influence of pH, temperature and carbon source (glucose and maltose) on growth rate and ethanol yield of Dekkera bruxellensis was investigated using a full-factorial design. Growth rate and ethanol yield were lower on maltose than on glucose. In controlled oxygen-limited batch cultivations, the ethanol yield of the different combinations varied from 0.42 to 0.45 g (g glucose)(-1) and growth rates varied from 0.037 to 0.050 h(-1). The effect of temperature on growth rate and ethanol yield was negligible. It was not possible to model neither growth rate nor ethanol yield from the full-factorial design, as only marginal differences were observed in the conditions tested. When comparing three D. bruxellensis strains and two industrial isolates of Saccharomyces cerevisiae, S. cerevisiae grew five times faster, but the ethanol yields were 0-13% lower. The glycerol yields of S. cerevisiae strains were up to six-fold higher compared to D. bruxellensis, and the biomass yields reached only 72-84% of D. bruxellensis. Our results demonstrate that D. bruxellensis is robust to large changes in pH and temperature and may have a more energy-efficient metabolism under oxygen limitation than S. cerevisiae.

  5. Physics of strained quantum well lasers

    CERN Document Server

    Loehr, John P

    1998-01-01

    When this publisher offered me the opportunity to \\\\Tite a book, some six years ago, I did not hesitate to say yes. I had just spent the last four years of graduate school struggling to understand the physics of strained quantum well lasers, and it seemed to me the whole experience was much more difficult that it should have been. For although many of the results I needed were easy to locate, the underlying physical premises and intervening steps were not. If only I had a book providing the derivations, I could have absorbed them and gone on my way. Such a book lies before you. It provides a unified and self-contained descrip­ tion of the essential physics of strained quantum well lasers, starting from first principles whenever feasible. The presentation I have chosen requires only the standard introductory background in quantum mechanics, solid state physics, and electromagnetics expected of entering graduate students in physics or elec­ trical engineering. A single undergraduate course in each of these su...

  6. Strain sweeps from Oldroyd 8-constant framework

    Science.gov (United States)

    Saengow, Chaimongkol; Giacomin, Alan Jeffrey

    2017-05-01

    Large-amplitude oscillatory shear flow is a popular experiment for studying the nonlinear physics of complex fluids. Specifically, the strain sweep is used routinely to identify when a complex fluid begins to exhibit nonlinear behavior. In this paper, we give the exact shear stress expression for the Oldroyd 8-constant framework evaluated for large-amplitude oscillatory shear flow (LAOS). We choose the Oldroyd 8-constant framework for its rich diversity of popular special cases (we list 14 of these cases). From our shear stress expression, we get exact expressions for the real and imaginary parts of the complex viscosity as functions of both the test frequency, and the shear rate amplitude. We then demonstrate the use of our results for our favorite special case of the Oldroyd 8-constant framework, the corotational Jeffreys model. In our Worked Example, we use this case to explore the influence of η∞ on the strain sweep response. We find that increasing η∞ raises the real part of the complex viscosity, and decreases its imaginary part.

  7. Selection of Xilose-Fermenting Yeast Strains

    Directory of Open Access Journals (Sweden)

    Rosimeire Oenning da Silva

    Full Text Available ABSTRACT In Brazil, ethanol is obtained by fermentat of sugar cane juice using Saccharomyces cerevisiae. The cane juice extraction generates the bagasse that has been used for obtaining generation biofuel. However, the sugarcane bagasse has 30% pentose that cannot be fermented to ethanol by S. cerevisiae. Thus the aim of this study was to isolate a yeast able to ferment xylose to ethanol. Samples of cane juice and flowers were used for the isolation of 165 strains that were then screened for ethanol production using plate testing. Among them, the ethanol positive strains Wickerhamomyces anomalus, Schizosaccharomyces pombe and Starmerella meliponinorum were selected for a xylose fermentation assay, using a semi-synthetic and bagasse hydrolysate as must. S. meliponinorum and S. pombe produced 0.63 and 2.7 gL-1 of ethanol, respectively, from xylose in a semisynthetic medium. In the medium consisting of bagasse hydrolysate must, 0.67 and 1.1 gL-1 of ethanol were obtained from S. meliponinorum and S. pombe, respectively. All the yeasts produced xylitol from xylose in the semisynthetic medium and S. meliponinorum was that which produced the highest quantity (14.5 g L-1.

  8. Mutational landscape of yeast mutator strains.

    Science.gov (United States)

    Serero, Alexandre; Jubin, Claire; Loeillet, Sophie; Legoix-Né, Patricia; Nicolas, Alain G

    2014-02-04

    The acquisition of mutations is relevant to every aspect of genetics, including cancer and evolution of species on Darwinian selection. Genome variations arise from rare stochastic imperfections of cellular metabolism and deficiencies in maintenance genes. Here, we established the genome-wide spectrum of mutations that accumulate in a WT and in nine Saccharomyces cerevisiae mutator strains deficient for distinct genome maintenance processes: pol32Δ and rad27Δ (replication), msh2Δ (mismatch repair), tsa1Δ (oxidative stress), mre11Δ (recombination), mec1Δ tel1Δ (DNA damage/S-phase checkpoints), pif1Δ (maintenance of mitochondrial genome and telomere length), cac1Δ cac3Δ (nucleosome deposition), and clb5Δ (cell cycle progression). This study reveals the diversity, complexity, and ultimate unique nature of each mutational spectrum, composed of punctual mutations, chromosomal structural variations, and/or aneuploidies. The mutations produced in clb5Δ/CCNB1, mec1Δ/ATR, tel1Δ/ATM, and rad27Δ/FEN1 strains extensively reshape the genome, following a trajectory dependent on previous events. It comprises the transmission of unstable genomes that lead to colony mosaicisms. This comprehensive analytical approach of mutator defects provides a model to understand how genome variations might accumulate during clonal evolution of somatic cell populations, including tumor cells.

  9. Uniaxial tension test on Rubber at constant true strain rate

    Directory of Open Access Journals (Sweden)

    Sourne H.L.

    2012-08-01

    Full Text Available Elastomers are widely used for damping parts in different industrial contexts because of their remarkable dissipation properties. Indeed, they can undergo severe mechanical loading conditions, i.e., high strain rates and large strains. Nevertheless, the mechanical response of these materials can vary from purely rubber-like to glassy depending on the strain rate undergone. Classically, uniaxial tension tests are made in order to find a relation between the stress and the strain in the material at various strain rates. However, even if the strain rate is searched to be constant, it is the nominal strain rate that is considered. Here we develop a test at constant true strain rate, i.e. the strain rate that is experienced by the material. In order to do such a test, the displacement imposed by the machine is an exponential function of time. This test has been performed with a high speed hydraulic machine for strain rates between 0.01/s and 100/s. A specific specimen has been designed, yielding a uniform strain field (and so a uniform stress field. Furthermore, an instrumented aluminum bar has been used to take into account dynamic effects in the measurement of the applied force. A high speed camera enables the determination of strain in the sample using point tracking technique. Using this method, the stress-strain curve of a rubber-like material during a loading-unloading cycle has been determined, up to a stretch ratio λ = 2.5. The influence of the true strain rate both on stiffness and on dissipation of the material is then discussed.

  10. [Isolation and identification of Cronobacter (Enterobacter sakazakii) strains from food].

    Science.gov (United States)

    Dong, Xiaohui; Li, Chengsi; Wu, Qingping; Zhang, Jumei; Mo, Shuping; Guo, Weipeng; Yang, Xiaojuan; Xu, Xiaoke

    2013-05-04

    This study aimed to detect and quantify Cronobacter in 300 powdered milk samples and 50 non-powdered milk samples. Totally, 24 Cronobacter (formerly Enterobacter sakazakii) strains isolated from powdered milk and other foods were identified and confirmed. Cronobacter strains were detected quantitatively using most probable number (MPN) method and molecular detection method. We identified 24 Cronobacter strains using biochemical patterns, including indole production and dulcitol, malonate, melezitose, turanose, and myo-Inositol utilization. Of the 24 strains, their 16S rRNA genes were sequenced, and constructed phylogenetic tree by N-J (Neighbour-Joining) with the 16S rRNA gene sequences of 17 identified Cronobacter strains and 10 non-Cronobacter strains. Quantitative detection showed that Cronobacter strains were detected in 23 out of 350 samples yielding 6.6% detection rate. Twenty-four Cronobacter strains were isolated from 23 samples and the Cronobacter was more than 100 MPN/100g in 4 samples out of 23 samples. The 24 Cronobacter spp. isolates strains were identified and confirmed, including 19 Cronobacter sakazakii strains, 2 C. malonaticus strains, 2 C. dubliensis subsp. lactaridi strains, and 1 C. muytjensii strain. The combination of molecular detection method and most probable number (MPN) method could be suitable for the detection of Cronobacter in powdered milk, with low rate of contamination and high demand of quantitative detection. 24 isolated strains were confirmed and identified by biochemical patterns and molecular technology, and C. sakazakii could be the dominant species. The problem of Cronobacter in powdered milk should be a hidden danger to nurseling, and should catch the government and consumer's attention.

  11. Splicing landscape of the eight collaborative cross founder strains.

    Science.gov (United States)

    Zheng, Christina L; Wilmot, Beth; Walter, Nicole Ar; Oberbeck, Denesa; Kawane, Sunita; Searles, Robert P; McWeeney, Shannon K; Hitzemann, Robert

    2015-02-05

    The Collaborative Cross (CC) is a large panel of genetically diverse recombinant inbred mouse strains specifically designed to provide a systems genetics resource for the study of complex traits. In part, the utility of the CC stems from the extensive genome-wide annotations of founder strain sequence and structural variation. Still missing, however, are transcriptome-specific annotations of the CC founder strains that could further enhance the utility of this resource. We provide a comprehensive survey of the splicing landscape of the 8 CC founder strains by leveraging the high level of alternative splicing within the brain. Using deep transcriptome sequencing, we found that a majority of the splicing landscape is conserved among the 8 strains, with ~65% of junctions being shared by at least 2 strains. We, however, found a large number of potential strain-specific splicing events as well, with an average of ~3000 and ~500 with ≥3 and ≥10 sequence read coverage, respectively, within each strain. To better understand strain-specific splicing within the CC founder strains, we defined criteria for and identified high-confidence strain-specific splicing events. These splicing events were defined as exon-exon junctions 1) found within only one strain, 2) with a read coverage ≥10, and 3) defined by a canonical splice site. With these criteria, a total of 1509 high-confidence strain-specific splicing events were identified, with the majority found within two of the wild-derived strains, CAST and PWK. Strikingly, the overwhelming majority, 94%, of these strain-specific splicing events are not yet annotated. Strain-specific splicing was also located within genomic regions recently reported to be over- and under-represented within CC populations. Phenotypic characterization of CC populations is increasing; thus these results will not only aid in further elucidating the transcriptomic architecture of the individual CC founder strains, but they will also help in guiding

  12. Strain bidimensional na cardiopatia de Takotsubo Two-dimensional strain in Takotsubo cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Carlos Bellini G. Gomes

    2010-08-01

    Full Text Available Este relato apresenta o seguimento tardio de um caso de cardiomiopatia de Takotsubo com boa evolução clínica e melhora da função sistólica global ventricular esquerda. Contudo, observou-se persistência de significativa disfunção sistólica regional longitudinal que foi avaliada por meio de nova técnica ecocardiográfica (speckle tracking, com as medidas do strain (S e strain rate (SR correspondentes. Ressaltamos a importância desse novo método para o acompanhamento dessa cardiopatia, pois permite identificar os pacientes que persistem com disfunção sistólica e que possivelmente serão beneficiados com a manutenção da terapêutica clínica.This report presents the late follow-up of a case of Takotsubo cardiomyopathy with good clinical outcome and improved left ventricular global systolic function. However, there was persistence of significant regional longitudinal systolic dysfunction evaluated using a new echocardiographic technique (speckle tracking, with corresponding measures of strain (S and strain rate (SR. We emphasize the importance of this new method to monitoring this cardiomyopathy, since it identifies patients with persistent systolic dysfunction who will possibly benefit from maintenance of clinical therapy

  13. Bacillus amyloliquefaciens strain 32a as a source of lipopeptides for biocontrol of Agrobacterium tumefaciens strains.

    Science.gov (United States)

    Ben Abdallah, D; Frikha-Gargouri, O; Tounsi, S

    2015-07-01

    A Bacillus amyloliquefaciens strain, designated 32a, was used to identify new compounds active against Agrobacterium tumefaciens and to evaluate their efficiency to control crown gall on carrot discs. Based on PCR-assays, four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A, bacillomycin D and fengycin. Mass spectrometry analysis of culture supernatant led to the identification of these secondary metabolites, except bacillomycin, with heterogeneous mixture of homologues. Antimicrobial assays using lipopeptides-enriched extract showed a strong inhibitory activity against several bacterial and fungal strains, including Ag. tumefaciens. Biological control assays on carrot discs using both 32a spores and extract resulted in significant protection against crown gall disease, similar to that provided by the reference antagonistic strain Agrobacterium rhizogenes K1026. In contrast to all active compounds against Ag. tumefaciens that are of proteinaceous nature, this work enables for the first time to correlate the strong protective effect of B. amyloliquefaciens strain 32a towards crown gall disease with the production of a mixture of lipopeptides. The findings could be useful for growers and nursery men who are particularly interested in the biocontrol of the crown gall disease. © 2015 The Society for Applied Microbiology.

  14. Finite Strain Behavior of Polyurea for a Wide Range of Strain Rates

    Science.gov (United States)

    2010-02-01

    open loop mode, the user can preset the position of the inlet servo valve. Furthermore, the initial pressure of the in-flowing fluid may be controlled... Mecanique , 13:679-713. [94] Simo, J.C. (1987) "On a fully 3-dimensional finite-strain viscoelastic damage model - Formulation and computational aspects

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

    Science.gov (United States)

    2013-01-01

    DC, USA 2Code 6394 Computational Multiphysics Systems Laboratory, Center of Computational Material Science, Naval Research Laboratory, Washington DC... Shearography [16–18] and Moiré interferometry [19, 20] that exploit implicit differentiations of the displacement fields, com- pute only a subset of the strain...Michopoulos, Code 6394 Computational Multiphysics Systems Laboratory, Center of Computational Material Science, Naval Research Laboratory, Washington DC

  16. The MG1363 and IL1403 Laboratory Strains of Lactococcus lactis and Several Dairy Strains Are Diploid

    DEFF Research Database (Denmark)

    Michelsen, Ole; Hansen, Flemming G.; Albrechtsen, B.

    2010-01-01

    Bacteria are normally haploid, maintaining one copy of their genome in one circular chromosome. We have examined the cell cycle of laboratory strains of Lactococcus lactis, and, to our surprise, we found that some of these strains were born with two complete nonreplicating chromosomes. We...... determined the cellular content of DNA by flow cytometry and by radioactive labeling of the DNA. These strains thus fulfill the criterion of being diploid. Several dairy strains were also found to be diploid while a nondairy strain and several other dairy strains were haploid in slow-growing culture....... The diploid and haploid strains differed in their sensitivity toward UV light, in their cell size, and in their D period, the period between termination of DNA replication and cell division....

  17. Bias in the Listeria monocytogenes enrichment procedure: Lineage 2 strains outcompete lineage 1 strains in University of Vermont selective enrichments

    DEFF Research Database (Denmark)

    Bruhn, Jesper Bartholin; Vogel, Birte Fonnesbech; Gram, Lone

    2005-01-01

    of the present study was to investigate if the selective enrichment procedure results in a true representation of the subtypes of L. monocytogenes present in a sample. Eight L. monocytogenes strains (four lineage 1 strains and four lineage 2 strains) and one Listeria innocua strain grew with identical growth...... tested, indicating a bias in strains selected by the enrichment procedures. Bias also occurred when coinoculating two lineage 2 or lineage 1 strains; however, it did not appear to correlate with origin (clinical versus food). Identical coinoculation experiments in BHI suggested that the selective......Listeria monocytogenes can be isolated from a range of food products and may cause food-borne outbreaks or sporadic cases of listeriosis. L. monocytogenes is divided into three genetic lineages and 13 serotypes. Strains of three serotypes (1/2a, 1/2b, and 4b) are associated with most human cases...

  18. Finite Element Modeling of the Behavior of Armor Materials Under High Strain Rates and Large Strains

    Science.gov (United States)

    Polyzois, Ioannis

    For years high strength steels and alloys have been widely used by the military for making armor plates. Advances in technology have led to the development of materials with improved resistance to penetration and deformation. Until recently, the behavior of these materials under high strain rates and large strains has been primarily based on laboratory testing using the Split Hopkinson Pressure Bar apparatus. With the advent of sophisticated computer programs, computer modeling and finite element simulations are being developed to predict the deformation behavior of these metals for a variety of conditions similar to those experienced during combat. In the present investigation, a modified direct impact Split Hopkinson Pressure Bar apparatus was modeled using the finite element software ABAQUS 6.8 for the purpose of simulating high strain rate compression of specimens of three armor materials: maraging steel 300, high hardness armor (HHA), and aluminum alloy 5083. These armor materials, provided by the Canadian Department of National Defence, were tested at the University of Manitoba by others. In this study, the empirical Johnson-Cook visco-plastic and damage models were used to simulate the deformation behavior obtained experimentally. A series of stress-time plots at various projectile impact momenta were produced and verified by comparison with experimental data. The impact momentum parameter was chosen rather than projectile velocity to normalize the initial conditions for each simulation. Phenomena such as the formation of adiabatic shear bands caused by deformation at high strains and strain rates were investigated through simulations. It was found that the Johnson-Cook model can accurately simulate the behavior of body-centered cubic (BCC) metals such as steels. The maximum shear stress was calculated for each simulation at various impact momenta. The finite element model showed that shear failure first occurred in the center of the cylindrical specimen and

  19. Immunity raised by recent European subtype 1 PRRSV strains allows better replication of East European subtype 3 PRRSV strain Lena than that raised by an older strain

    DEFF Research Database (Denmark)

    Trus, Ivan; Frydas, Ilias S.; Reddy, Vishwanatha R. A. P.

    2016-01-01

    Stable spatial distribution of porcine reproductive and respiratory syndrome (PRRSV)-1 subtypes in Europe is accompanied by a strong population immunity induced by local PRRSV strains. In the present study, it was examined if the immunity induced by three West European subtype 1 PRRSV strains (20...

  20. Determination of strain hardening parameters of tailor hardened boron steel up to high strains using inverse FEM optimization and strain field matching

    NARCIS (Netherlands)

    Eller, Tom; Greve, L; Andres, M.T.; Medricky, M; Meinders, Vincent T.; van den Boogaard, Antonius H.

    2016-01-01

    In this article, an inverse FEM optimization strategy is proposed for identification of the strain hardening parameters of boron alloyed steel 22MnB5 in five different hardness grades. In the proposed elasto-plastic constitutive model, the strain hardening is represented by a nonlinear combination

  1. Elastically relaxed free-standing strained-silicon nanomembranes.

    Science.gov (United States)

    Roberts, Michelle M; Klein, Levente J; Savage, Donald E; Slinker, Keith A; Friesen, Mark; Celler, George; Eriksson, Mark A; Lagally, Max G

    2006-05-01

    Strain plays a critical role in the properties of materials. In silicon and silicon-germanium, strain provides a mechanism for control of both carrier mobility and band offsets. In materials integration, strain is typically tuned through the use of dislocations and elemental composition. We demonstrate a versatile method to control strain by fabricating membranes in which the final strain state is controlled by elastic strain sharing, that is, without the formation of defects. We grow Si/SiGe layers on a substrate from which they can be released, forming nanomembranes. X-ray-diffraction measurements confirm a final strain predicted by elasticity theory. The effectiveness of elastic strain to alter electronic properties is demonstrated by low-temperature longitudinal Hall-effect measurements on a strained-silicon quantum well before and after release. Elastic strain sharing and film transfer offer an intriguing path towards complex, multiple-layer structures in which each layer's properties are controlled elastically, without the introduction of undesirable defects.

  2. Bacteriocin production and gene sequencing analysis from vaginal Lactobacillus strains.

    Science.gov (United States)

    Stoyancheva, Galina; Marzotto, Marta; Dellaglio, Franco; Torriani, Sandra

    2014-09-01

    The human vagina is a complex and dynamic ecosystem containing an abundance of microorganisms. In women of childbearing age, this system is dominated by Lactobacillus spp. In the present work, seventeen newly isolated vaginal strains were identified by 16S rDNA sequencing and were investigated for their antimicrobial properties. Twelve of the isolated Lactobacillus strains showed activity against one or more microorganisms. Six and five of them produced substances that inhibited the growth of two different Klebsiella strains and Staphylococcus aureus, respectively. Two lactobacilli strains were active against an Escherichia coli strain, one isolate was active against an Enterococus faecalis strain and another lactobacilli strain showed antimicrobial activity against a Candida parapsilosis strain. The nature of the active compounds was additionally studied, and the presence of bacteriocin-like substances was proved. The genes related to the bacteriocin production in three of the newly isolated strains were identified and sequenced. The presence of gassericin A operon in the genome of the species Lactobacillus crispatus was described for the first time. The presence of antimicrobial activity contributes to their possible use as potential probiotic strains after further research.

  3. Testing of fiber composites at high strain rates

    Science.gov (United States)

    Daniel, I. M.; Liber, T.

    1978-01-01

    An experimental investigation was conducted to determine strain rate effects in fiber composites. Unidirectional composite specimens of boron/epoxy, graphite/epoxy, S-glass/epoxy and Kevlar/epoxy were tested at tensile strain rates of up to 27 m/m/sec. Longitudinal, transverse and in-plane shear properties, including modulus, Poisson's ratio, strength and ultimate strain, were determined by testing 0-, 90and 10-degree unidirectional coupons. Strains were measured by means of strain gages bonded on the coupons and loads were measured by means of a strain gage load cell. All specimens were loaded in an electrohydraulic loading system. The 0-degree properties which are governed by the fibers do not vary much with strain rate except for the Kevlar/epoxy material which shows an increase in both modulus and strength. The strain rate effects on 90-degree properties were small with a general trend toward higher strength with increasing strain rate. The most noticeable effect was on in-plane shear properties with shear strength values at high strain rates approximately fifteen percent higher than static values.

  4. Principal Strain Vascular Elastography: Simulation and Preliminary Clinical Evaluation.

    Science.gov (United States)

    Nayak, Rohit; Huntzicker, Steven; Ohayon, Jacques; Carson, Nancy; Dogra, Vikram; Schifitto, Giovanni; Doyley, Marvin M

    2017-03-01

    It is difficult to produce reliable polar strain elastograms (radial and circumferential) because the center of the carotid artery is typically unknown. Principal strain imaging can overcome this limitation, but suboptimal lateral displacement estimates make this an impractical approach for visualizing mechanical properties within the carotid artery. We hypothesized that compounded plane wave imaging can minimize this problem. To test this hypothesis, we performed (i) simulations with vessels of varying morphology and mechanical behavior (i.e., isotropic and transversely isotropic), and (ii) a pilot study with 10 healthy volunteers. The accuracy of principal and polar strain (computed using knowledge of the precise vessel center) elastograms varied between 7% and 17%. In both types of elastograms, strain concentrated at the junction between the fibrous cap and the vessel wall, and the strain magnitude decreased with increasing fibrous cap thickness. Elastograms of healthy volunteers were consistent with those of transversely isotropic homogeneous vessels; they were spatially asymmetric, a trend that was common to both principal and polar strains. No significant differences were observed in the mean strain recovered from principal and polar strains (p > 0.05). This investigation indicates that principal strain elastograms measured with compounding plane wave imaging overcome the problems incurred when polar strain elastograms are computed with imprecise estimates of the vessel center. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  5. Atomistic simulations of focused ion beam machining of strained silicon

    Science.gov (United States)

    Guénolé, J.; Prakash, A.; Bitzek, E.

    2017-09-01

    The focused ion beam (FIB) technique has established itself as an indispensable tool in the material science community, both to analyze samples and to prepare specimens by FIB milling. In combination with digital image correlation (DIC), FIB milling can, furthermore, be used to evaluate intrinsic stresses by monitoring the strain release during milling. The irradiation damage introduced by such milling, however, results in a change in the stress/strain state and elastic properties of the material; changes in the strain state in turn affect the bonding strength, and are hence expected to implicitly influence irradiation damage formation and sputtering. To elucidate this complex interplay between strain, irradiation damage and sputtering, we perform TRIM calculations and molecular dynamics simulations on silicon irradiated by Ga+ ions, with slab and trench-like geometries, whilst simultaneously applying uniaxial tensile and compressive strains up to 4%. In addition we calculate the threshold displacement energy (TDE) and the surface binding energy (SBE) for various strain states. The sputter rate and amount of damage produced in the MD simulations show a clear influence of the strain state. The SBE shows no significant dependence on strain, but is strongly affected by surface reconstructions. The TDE shows a clear strain-dependence, which, however, cannot explain the influence of strain on the extent of the induced irradiation damage or the sputter rate.

  6. Nutritional values of different strains of mushrooms (Agaricus bisporus

    Directory of Open Access Journals (Sweden)

    Józef Bąkowski

    2013-12-01

    Full Text Available The nutritional values and chemical composition of different strains of the mushroom (Agaricus bisporus were studied. The study covered four strains cultivated in Poland: OCNOS-1, Somycel-11 , Somycel-92, and Somycel-653. The samples were analyzed for dry matter, vitamin C, nitrates, nitrites, total nitrogen and crude protein (N × 4.38, amino acid composition, soluble carbohydrates composition, and minerals content. Besides, whiteness values were determined by Hunter's method. All determinations were made on two of fruit-bodies of two sizes: 25-40 mm in pileus diameter (small and 40-50 mm in pileus diameter (large. A significantly higher dry matter content was found in strain 1 in comparison with strain 92. The lowest value of total nitrogen was detected for strain 92 and the highest for strain 653. From among the four analyzed strains, strain 92 contained the highest amount of essential amino acids. Trehalose content was significantly lower in strain 11 in comparison with other strains both in small and large fruit-body.

  7. Evidence for a radial strain gradient in apple fruit cuticles.

    Science.gov (United States)

    Khanal, Bishnu Prasad; Knoche, Moritz; Bußler, Sara; Schlüter, Oliver

    2014-10-01

    The morphological outer side of the apple fruit cuticle is markedly more strained than the inner side. This strain is released upon wax extraction. This paper investigates the effect of ablating outer and inner surfaces of isolated cuticular membranes (CM) of mature apple (Malus × domestica) fruit using cold atmospheric pressure plasma (CAPP) on the release of strain after extraction of waxes. Strain release was quantified as the decrease in area of CM discs following CAPP treatment and subsequent solvent extraction of wax. Increasing duration of CAPP treatment proportionally decreased CM mass per unit area. There was no difference in mass loss rate between CAPP treatments of outer or inner surfaces. Also, there was no difference in surface area of CMs before and after CAPP treatment. However, upon subsequent wax extraction, surface area of CMs decreased indicating the release of strain. Increasing the duration of CAPP treatment resulted in increasing strain release up to 47.7 ± 8.0 % at 20 min when CAPP was applied to the inner surface. In contrast, strain release was independent of CAPP duration averaging about 12.1 ± 0.6 % when applied to the outer surface of the CM. Our results provide evidence for a marked gradient of strain between the outer side (strained) and the inner side of the CM (not strained) of mature apple fruit.

  8. Antimicrobial drug susceptibility of Neisseria meningitidis strains isolated from carriers

    Directory of Open Access Journals (Sweden)

    Dayamí García

    2000-06-01

    Full Text Available When it is necessary to determine the susceptibility of Neisseria meningitidis (Nm strains to antimicrobial drugs, it is important to consider that it should be analyzed in a double context. One of them related to the use of drugs in a specific medical treatment; and the other; to chemoprophylatic drugs, both with the same purpose: the accurate selection of the “in vivo” antimicrobial agent. This requires the study of the sensitivity and resistance of strains isolated in both carriers and patients. With the aim of further studying the behavior of the strains that currently circulate in Cuba, an antimicrobial drug susceptibility study was conducted in 90 strains isolated from carriers during the first half of 1998. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs to: penicillin, ampicillin, rifampin, sulfadiazine, chloramphenicol, ciprofloxacin, ceftriaxone, cefotaxime. The study of the three latter drugs was done for the first time in our country. The search for β- lactamase-producer strains was also performed. There was a predominance of penicillin sensitive strains (82,2% with an intermediate sensitivity to ampicillin (57,8%, while 70% of the strains were sensitive to sulfadiazine. Regarding the rest of the antimicrobial drugs, 100% of the strains were sensitive. The paper shows the MICs for each drug as well as the phenotypic characteristics of the strains with the penicillin and sulfadiazine sensitivity and resistance patterns. No β-lactamase-producer strains were found.

  9. Identification of Bacillus Strains for Biological Control of Catfish Pathogens

    Science.gov (United States)

    Ran, Chao; Carrias, Abel; Williams, Malachi A.; Capps, Nancy; Dan, Bui C. T.; Newton, Joseph C.; Kloepper, Joseph W.; Ooi, Ei L.; Browdy, Craig L.; Terhune, Jeffery S.; Liles, Mark R.

    2012-01-01

    Bacillus strains isolated from soil or channel catfish intestine were screened for their antagonism against Edwardsiella ictaluri and Aeromonas hydrophila, the causative agents of enteric septicemia of catfish (ESC) and motile aeromonad septicaemia (MAS), respectively. Twenty one strains were selected and their antagonistic activity against other aquatic pathogens was also tested. Each of the top 21 strains expressed antagonistic activity against multiple aquatic bacterial pathogens including Edwardsiella tarda, Streptococcus iniae, Yersinia ruckeri, Flavobacterium columnare, and/or the oomycete Saprolegnia ferax. Survival of the 21 Bacillus strains in the intestine of catfish was determined as Bacillus CFU/g of intestinal tissue of catfish after feeding Bacillus spore-supplemented feed for seven days followed by normal feed for three days. Five Bacillus strains that showed good antimicrobial activity and intestinal survival were incorporated into feed in spore form at a dose of 8×107 CFU/g and fed to channel catfish for 14 days before they were challenged by E. ictaluri in replicate. Two Bacillus subtilis strains conferred significant benefit in reducing catfish mortality (PBacillus strains also showed protective effects against E. ictaluri in striped catfish. Safety of the four strains exhibiting the strongest biological control in vivo was also investigated in terms of whether the strains contain plasmids or express resistance to clinically important antibiotics. The Bacillus strains identified from this study have good potential to mediate disease control as probiotic feed additives for catfish aquaculture. PMID:23029244

  10. Curvature reduces bending strains in the quokka femur

    Directory of Open Access Journals (Sweden)

    Kyle McCabe

    2017-03-01

    Full Text Available This study explores how curvature in the quokka femur may help to reduce bending strain during locomotion. The quokka is a small wallaby, but the curvature of the femur and the muscles active during stance phase are similar to most quadrupedal mammals. Our hypothesis is that the action of hip extensor and ankle plantarflexor muscles during stance phase place cranial bending strains that act to reduce the caudal curvature of the femur. Knee extensors and biarticular muscles that span the femur longitudinally create caudal bending strains in the caudally curved (concave caudal side bone. These opposing strains can balance each other and result in less strain on the bone. We test this idea by comparing the performance of a normally curved finite element model of the quokka femur to a digitally straightened version of the same bone. The normally curved model is indeed less strained than the straightened version. To further examine the relationship between curvature and the strains in the femoral models, we also tested an extra-curved and a reverse-curved version with the same loads. There appears to be a linear relationship between the curvature and the strains experienced by the models. These results demonstrate that longitudinal curvature in bones may be a manipulable mechanism whereby bone can induce a strain gradient to oppose strains induced by habitual loading.

  11. Thoracolumbar spinal ligaments exhibit negative and transverse pre-strain.

    Science.gov (United States)

    Robertson, Daniel J; Von Forell, Gregory A; Alsup, Jeremy; Bowden, Anton E

    2013-07-01

    The present work represents the first reported bi-axial spinal ligament pre-strain data for the thoracic and lumbar spine. Ligament pre-strain (in-situ strain) is known to significantly alter joint biomechanics. However, there is currently a lack of comprehensive data with regards to spinal ligament pre-strain. The current work determined the pre-strain of 71 spinal ligaments (30 anterior longitudinal ligaments, 27 supraspinous ligaments and 14 interspinous ligaments). The interspinous ligament and the anterior longitudinal ligament exhibited bi-axial pre-strain distributions, demonstrating they are not uniaxial structures. The supraspinous ligament frequently exhibited large amounts of negative pre-strain or laxity suggesting it makes no mechanical contribution to spinal stability near the neutral posture. Upon implementing multi-axial pre-strain results into a finite element model of the lumbar spine, large differences in spinal biomechanics were observed. These results demonstrate the necessity of accounting for ligament pre-strain in biomechanical models. In addition, the authors present a unique experimental method for obtaining ligament pre-strain that presents a number of advantages when compared to standard techniques. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Influence of catheter position on estimated strain in intravascular elastography.

    Science.gov (United States)

    De Korte, C L; Cespedes, E I; Van Der Steen, A W

    1999-01-01

    In elastography, an erroneous strain estimate is obtained when the radial strain and the probing ultrasound beam are not properly aligned: the "strain projection artifact". In practice, an angle between the strain and the ultrasound beam will be present in most of the cases due to inhomogeneities or nonuniform compression. In this study, a theoretical function describing the strain projection artifact is derived as a function of the angle between the radial strain and the ultrasound beam. Two main factors for an angle between strain and ultrasound beam in intravascular elastographic experiments are eccentricity and tilt of the transducer. The theoretical functions describing these errors are corroborated with strain estimates from an experiment with a circular, homogeneous gel-based vessel phantom. Comparison between the theoretical functions and the experimental results reveals that the strain projection artifact is well described by the theoretical findings. As a result, the experimental data can be corrected for this artifact. The corrected elastograms reveal that correct strain estimates are obtained when the eccentricity of the intravascular catheter is less than 63%. An "off-the-wall" device may be required to advance intravascular elastography to in vivo implementation.

  13. A prospective study of iliotibial band strain in runners.

    Science.gov (United States)

    Hamill, Joseph; Miller, Ross; Noehren, Brian; Davis, Irene

    2008-10-01

    Iliotibial band syndrome is the leading cause of lateral knee pain in runners. It is thought that pain develops from strain on the iliotibial band due to friction of the iliotibial band sliding over the lateral femoral epicondyle. The purpose of this study was to investigate mechanical strain in the iliotibial band as a possible causative factor in the development of iliotibial band syndrome. From a large prospective study, female runners who incurred iliotibial band syndrome during the study were compared to a control group who incurred no injuries. Strain, strain rate and duration of impingement were determined from a musculoskeletal model of the lower extremity. The results indicated that the iliotibial band syndrome subjects exhibited greater strain throughout the support period, but particularly at midsupport compared to the control group. Strain rate was significantly greater in the iliotibial band syndrome group compared to the control group and was greater in the involved limb of the iliotibial band syndrome group compared to their contralateral limb. However, there were no differences in the duration of impingement between the groups. This study indicates that a major factor in the development of iliotibial band syndrome is strain rate. Therefore, we suggest that strain rate, rather than the magnitude of strain, may be a causative factor in developing iliotibial band syndrome. The effect size (>0.5) indicated that strain rate may be biologically significant in the etiology of iliotibial band syndrome.

  14. Strain-dependent carotenoid productions in metabolically engineered Escherichia coli.

    Science.gov (United States)

    Chae, Han Seung; Kim, Kong-Hwan; Kim, Sun Chang; Lee, Pyung Cheon

    2010-12-01

    Seven Escherichia coli strains, which were metabolically engineered with carotenoid biosynthetic pathways, were systematically compared in order to investigate the strain-specific formation of carotenoids of structural diversity. C30 acyclic carotenoids, diaponeurosporene and diapolycopene were well produced in all E. coli strains tested. However, the C30 monocyclic diapotorulene formation was strongly strain dependent. Reduced diapotorulene formation was observed in the E. coli strain Top10, MG1655, and MDS42 while better formation was observed in the E. coli strain JM109, SURE, DH5a, and XL1-Blue. Interestingly, C40 carotenoids, which have longer backbones than C30 carotenoids, also showed strain dependency as C30 diapotorulene did. Quantitative analysis showed that the SURE strain was the best producer for C40 acyclic lycopene, C40 dicyclic β-carotene, and C30 monocyclic diapotorulene. Of the seven strains examined, the highest volumetric productivity for most of the carotenoids structures was observed in the recombinant SURE strain. In conclusion, we showed that recombinant hosts and carotenoid structures influenced carotenoid productions significantly, and this information can serve as the basis for the subsequent development of microorganisms for carotenoids of interest.

  15. Differentiation of mycoplasma gallisepticum strains using molecular methods.

    Science.gov (United States)

    Biró, Judit; Erdei, Noémi; Székely, Ibolya; Stipkovits, L

    2006-12-01

    Increasing use of Mycoplasma gallisepticum (MG) live vaccines has led to a need for the differentiation of MG strains. The MG strains MK-7, MS-16, S6, FS-9 and R strains and the MG live vaccine strain F were compared by random amplification of polymorphic DNA (RAPD) in this study. Using RAPD, different patterns were found among the MG strains. In addition to this, we examined the differentiating potential of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) primers targeted at the crmA, crmB, crmC, gapA, mgc2 and pvpA genes encoding cytadherence-related surface proteins. These proteins may take part in the pathogenesis of MG-induced disease. Differentiation of strain F is based on the identification of restriction enzyme sites in the PCR amplicons. Using HphI enzyme, crmC PCR amplicons produced different RFLP patterns. Digestion of amplicons of gapA-specific PCR with MboI enzyme also produced distinct patterns. Differences were observed among strains R and F by digestion of mgc2 PCR amplicons with HaelIl and VspI enzymes and digestion of pvpA PCR amplicons with AccI, PvulI and ScrFI endonucleases. This method can be used for the rapid differentiation of vaccine strain from wild strains. Differentiation of MG strains is a great advantage for diagnosticians or practitioners and it is useful for epidemiological studies.

  16. Serological characterization of Actinobacillus pleuropneumoniae biotype 1 strains antigenically related to both serotypes 2 and 7

    DEFF Research Database (Denmark)

    Nielsen, R.; Andresen, Lars Ole; Plambeck, Tamara

    1996-01-01

    Nine Danish Actinobacillus pleuropneumoniae biotype 1 isolates were shown by latex agglutination and indirect haemagglutination to possess capsular polysaccharide epitopes identical to those of serotype 2 strain 1536 (reference strain of serotype 2) and strain 4226 (Danish serotype 2 strain...

  17. Easy storage strategies for Sporothrix spp. strains.

    Science.gov (United States)

    Brilhante, Raimunda Sâmia Nogueira; Silva, Natalya Fechine; Lima, Rita Amanda Chaves de; Caetano, Érica Pacheco; Alencar, Lucas Pereira de; Castelo-Branco, Débora de Souza Collares Maia; Moreira, José Luciano Bezerra; Bandeira, Silviane Praciano; Camargo, Zoilo Pires de; Rodrigues, Anderson Messias; Bandeira, Tereza de Jesus Pinheiro Gomes; Monteiro, André Jalles; Cordeiro, Rossana de Aguiar; Sidrim, José Júlio Costa; Rocha, Marcos Fábio Gadelha

    2015-04-01

    The present study evaluated the maintenance of Sporothrix spp. (6 Sporothrix brasiliensis; 6 S. schenckii; 5 S. mexicana, and 3 S. globosa) in saline at 4°C, and in 10% glycerol plus either 10% lactose or 10% sucrose, at -20°C and -80°C. Viability was assessed after 3, 6, and 9 months of storage, through the recovery of strains on potato dextrose agar and analysis of macro- and micromorphological features. Conidium quantification was performed before and after storage, at 3, 6 and 9 months. 100% viability was observed, regardless of storage conditions or time period. Storage at 4°C and at -20°C did not alter the number of conidia, but lower conidium counts were observed at -80°C. This study shows that the combination of glycerol with lactose or sucrose is effective to maintain Sporothrix spp. at freezing temperatures.

  18. 3D shearography for surface strain analysis

    Science.gov (United States)

    James, Stephen W.; Tatam, Ralph P.

    1999-10-01

    The development of a time-division-multiplexed 3D digital shearography instrument is described. The system provides simultaneous measurement of the in-plane and out-of-plane deformation gradients, allowing full surface strain analysis. The object under investigation is sequentially illuminated from three directions by three fiber coupled high power laser diode sources, and imaged onto a CCD camera through a single shearing interferometer. The pulsing of the sources is synchronized with the camera frame rate. Phase stepping is achieved using laser diode wavelength tuning combined with a path length imbalance in the shearing interferometer. The source pulsing schedule and image acquisition are controlled from a PC. An analysis of the optimum illumination geometry is presented. The performance of the system is evaluated on laboratory test samples.

  19. Quantum ballistic transport in strained epitaxial germanium

    Science.gov (United States)

    Gul, Y.; Holmes, S. N.; Newton, P. J.; Ellis, D. J. P.; Morrison, C.; Pepper, M.; Barnes, C. H. W.; Myronov, M.

    2017-12-01

    Large scale fabrication using Complementary Metal Oxide Semiconductor compatible technology of semiconductor nanostructures that operate on the principles of quantum transport is an exciting possibility now due to the recent development of ultra-high mobility hole gases in epitaxial germanium grown on standard silicon substrates. We present here a ballistic transport study of patterned surface gates on strained Ge quantum wells with SiGe barriers, which confirms the quantum characteristics of the Ge heavy hole valence band structure in 1-dimension. Quantised conductance at multiples of 2e2/h is a universal feature of hole transport in Ge up to 10 × (2e2/h). The behaviour of ballistic plateaus with finite source-drain bias and applied magnetic field is elucidated. In addition, a reordering of the ground state is observed.

  20. Strained Compromises? Danish Flexicurity During Crisis

    DEFF Research Database (Denmark)

    Ibsen, Christian Lyhne

    2011-01-01

    . The article therefore introduces, ‘centralized decentralization’ – a concept that directs our attention to forms of flexibility and security primarily for people in work. Most studies on Danish flexicurity have been carried out under favorable economic conditions. In light of the economic slump hitting....... For example the case studies show that the hypothesized preference for external numerical flexibility is perhaps too crude as employers use different ways to restructure employment. Especially the examples of de facto concessionary bargaining to save jobs are important here – although the extent...... of concessions is modest. The evidence thus suggests that the ‘Golden Triangle’ flexicurity compromises are indeed strained by the economic cycle and that responses to impetus for restructuring are far more nuanced than sometimes portrayed. It is argues that more company studies across national labor markets...

  1. High strain rate deformation of layered nanocomposites

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  2. Cryopreservation of basidiomycete strains using perlite.

    Science.gov (United States)

    Homolka, L; Lisá, L; Eichlerová, I; Nerud, F

    2001-12-01

    A new alternative method using perlite as a particulate solid carrier in the growth medium with a cryoprotectant was successfully tested for cryopreservation of several basidiomycete species from different genera (Armillaria, Pleurotus, Pluteus, Polyporus) which failed to survive or retain their properties in cryopreservation procedures routinely used in our laboratory. Frozen basidiomycete strains were kept in cryovials submerged in liquid nitrogen and were either immediately after the freezing process or after a 6-month storage thawed and checked for viability, purity and changes in growth, morphology and biochemical characteristics. All cultures survived the cryopreservation procedure and no negative effects of cryopreservation by this method have been observed after 6 months of storage in liquid nitrogen.

  3. Social relations: network, support and relational strain

    DEFF Research Database (Denmark)

    Due, P; Holstein, B; Lund, Rikke

    1999-01-01

    We introduce a conceptual framework with social relations as the main concept and the structure and the function of social relations as subconcepts. The structure of social relations covers aspects of formal relations and social network. The function of social relations covers social support......,011. The postal questionnaires were answered by a random sample in each of the age groups. The results show marked age and gender differences in both the structure and the function of social relations. The social network, measured as weekly contacts, weakens with age and so does instrumental support. Emotional...... support is unrelated to this decline in contact frequency and appears to be at the same level for younger and older individuals. Relational strain, measured as conflicts, declines with age for all kinds of social relations. The weakening of the social network with age does not seem to affect the level...

  4. Discrete shaped strain sensors for intelligent structures

    Science.gov (United States)

    Andersson, Mark S.; Crawley, Edward F.

    Design of discrete, highly distributed sensor systems for intelligent structures has been studied. Data obtained indicate that discrete strain-averaging sensors satisfy the functional requirements for distributed sensing of intelligent structures. Bartlett and Gauss-Hanning sensors, in particular, provide good wavenumber characteristics while meeting the functional requirements. They are characterized by good rolloff rates and positive Fourier transforms for all wavenumbers. For the numerical integration schemes, Simpson's rule is considered to be very simple to implement and consistently provides accurate results for five sensors or more. It is shown that a sensor system that satisfies the functional requirements can be applied to a structure that supports mode shapes with purely sinusoidal curvature.

  5. Associations between Mycobacterium tuberculosis Strains and Phenotypes

    Science.gov (United States)

    Brown, Timothy; Nikolayevskyy, Vladyslav; Velji, Preya

    2010-01-01

    To inform development of tuberculosis (TB) control strategies, we characterized a total of 2,261 Mycobacterium tuberculosis complex isolates by using multiple phenotypic and molecular markers, including polymorphisms in repetitive sequences (spoligotyping and variable-number tandem repeats [VNTRs]) and large sequence and single-nucleotide polymorphisms. The Beijing family was strongly associated with multidrug resistance (p = 0.0001), and VNTR allelic variants showed strong associations with spoligotyping families: >5 copies at exact tandem repeat (ETR) A, >2 at mycobacterial interspersed repetitive unit 24, and >3 at ETR-B associated with the East African–Indian and M. bovis strains. All M. tuberculosis isolates were differentiated into 4 major lineages, and a maximum parsimony tree was constructed suggesting a more complex phylogeny for M. africanum. These findings can be used as a model of pathogen global diversity. PMID:20113558

  6. Indices of Psychological Strain During Hypoxis Bedrest

    Science.gov (United States)

    Stavrou, Nektarios A.; McDonnell, Adam C.; Eiken, Ola; Mekjavic, Igor B.

    2013-02-01

    Much attention has been devoted to the physiological changes that occur during bed rest. However, there has been a lack of focus on the psychological aspects per se. We investigated indices of psychological strain during three 10-d interventions, designed to assess the combined effects of inactivity/unloading and normobaric hypoxia on several physiological systems. Eleven male participants underwent three 10-d campaigns in a randomized manner: 1) normobaric hypoxic ambulatory confinement (HAMB), 2) normobaric hypoxic bed rest (HBR) and 3) normoxic bed rest (NBR). The most negative psychological profile appeared on BR10 of HBR and HAmb conditions (hypoxic conditions). Concomitantly a decrease in positive emotions was observed from BR-2 to BR10. Bed rest and exposure to hypoxic environments seems to exert a negative effect on person’s psychological mood.

  7. Engineering clostridium strain to accept unmethylated DNA.

    Directory of Open Access Journals (Sweden)

    Hongjun Dong

    Full Text Available It is difficult to genetically manipulate the medically and biotechnologically important genus Clostridium due to the existence of the restriction and modification (RM systems. We identified and engineered the RM system of a model clostridial species, C. acetobutylicum, with the aim to allow the host to accept the unmethylated DNA efficiently. A gene CAC1502 putatively encoding the type II restriction endonuclease Cac824I was identified from the genome of C. acetobutylicum DSM1731, and disrupted using the ClosTron system based on group II intron insertion. The resulting strain SMB009 lost the type II restriction endonuclease activity, and can be transformed with unmethylated DNA as efficiently as with methylated DNA. The strategy reported here makes it easy to genetically modify the clostridial species using unmethylated DNA, which will help to advance the understanding of the clostridial physiology from the molecular level.

  8. Strain driven fast osseointegration of implants

    Directory of Open Access Journals (Sweden)

    Wiesmann Hans-Peter

    2005-09-01

    Full Text Available Abstract Background Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved. Methods We examined the bone reaction around non- and immediately loaded dental implants inserted in the mandible of mature minipigs during the presently assumed time for osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide surface, allowing direct bone contact after insertion. The external geometry was designed according to finite element analysis: the calculation showed that physiological amplitudes of strain (500–3,000 ustrain generated through mastication were homogenously distributed in peri-implant bone. The strain-energy density (SED rate under assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak dislocations were lower then nm. Results Bone was in direct contact to the implant surface (bone/implant contact rate 90% from day one of implant insertion, as quantified by undecalcified histological sections. This effect was substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond during the experimental period of either control or experimental animals, indicating that immediate load had no adverse effect on bone structure in peri-implant bone. Conclusion In terms of clinical relevance, the load related bone reaction at the implant interface may in combination with substrate effects be responsible for an immediate osseointegration state.

  9. Alteration in left ventricular normal and shear strains evaluated by 2D-strain echocardiography in the athlete's heart

    Science.gov (United States)

    Nottin, S; Doucende, G; Schuster-Beck, I; Dauzat, M; Obert, P

    2008-01-01

    The contraction of cardiomyocytes induces a systolic increase in left ventricular (LV) normal (radial, circumferential and longitudinal) and shear strains, whose functional consequences have not been evaluated, so far, in athletes. We used 2D ultrasound speckle tracking imaging (STI) to evaluate LV regional strain in high-level cyclists compared to sedentary controls. Sixteen male elite cyclists and 23 sedentary controls underwent conventional, tissue Doppler, and STI echocardiography at rest. We assessed LV long and short axis normal strains and shear strains. We evaluated circumferential–longitudinal shear strain from LV torsion, and circumferential–radial shear strain from the difference between subendocardial and subepicardial torsion. Apical radial strain (42.7 ± 10.5%versus 52.2 ± 14.3%, P subendocardial than in the subepicardial region in sedentary controls, but not in cyclists. Haemodynamic and tissue Doppler based indexes of global LV diastolic and systolic functions were not different between cyclists and controls. Athlete's heart is associated with specific LV adaptation including lower apical strain and lower myocardial shear strains, with no change in global LV diastolic and systolic function. These mechanical alterations could improve the cardiovascular adjustments to exercise by increasing the radial strain and torsional (and thus untwisting) response to exercise, a key element of diastolic filling and thus of cardiac performance in athletes. PMID:18687717

  10. Ultra-responsive soft matter from strain-stiffening hydrogels

    Science.gov (United States)

    Jaspers, Maarten; Dennison, Matthew; Mabesoone, Mathijs F. J.; Mackintosh, Frederick C.; Rowan, Alan E.; Kouwer, Paul H. J.

    2014-12-01

    The stiffness of hydrogels is crucial for their application. Nature’s hydrogels become stiffer as they are strained. This stiffness is not constant but increases when the gel is strained. This stiffening is used, for instance, by cells that actively strain their environment to modulate their function. When optimized, such strain-stiffening materials become extremely sensitive and very responsive to stress. Strain stiffening, however, is unexplored in synthetic gels since the structural design parameters are unknown. Here we uncover how readily tuneable parameters such as concentration, temperature and polymer length impact the stiffening behaviour. Our work also reveals the marginal point, a well-described but never observed, critical point in the gelation process. Around this point, we observe a transition from a low-viscous liquid to an elastic gel upon applying minute stresses. Our experimental work in combination with network theory yields universal design principles for future strain-stiffening materials.

  11. Reclassification of 30 Pasteurellaceae strains isolated from rodents.

    Science.gov (United States)

    Boot, R; Bisgaard, M

    1995-07-01

    Thirty Pasteurellaceae strains isolated from gerbil, guineapig, hamster, mouse, muskrat and rat were reinvestigated and reclassified after comparison with reference strains. Strains originally described as Pasteurella pneumotropica were reclassified as [Pasteurella] pneumotropica Heyl biotype (7), [P.] pneumotropica Jawetz biotype (1), Pasteurella dagmatis (1) or Taxon 22 (2). Strains previously reported as Actinobacillus sp. were reclassified as [P.] pneumotropica biotype Jawetz (3), P. dagmatis (3) or Taxon 6 (7). Strains earlier described as Pasteurella gallinarum were renamed as SP group pasteurella (4) or Taxon 25 (2). Some of these reclassified Pasteurellaceae have not been reported previously in rodents. The present findings underline the importance of extended characterization of isolates and comparison with references strains to avoid misclassification within the family Pasteurellaceae Pohl 1981.

  12. Strain effects on rotational property in nanoscale rotation system.

    Science.gov (United States)

    Huang, Jianzhang; Han, Qiang

    2018-01-11

    This paper presents a study of strain effects on nanoscale rotation system consists of double-walls carbon nanotube and graphene. It is found that the strain effects can be a real-time controlling method for nano actuator system. The strain effects on rotational property as well as the effect mechanism is studied systematically through molecular dynamics simulations, and it obtains valuable conclusions for engineering application of rotational property management of nanoscale rotation system. It founds that the strain effects tune the rotational property by influencing the intertube supporting effect and friction effect of double-walls carbon nanotube, which are two critical factors of rotational performance. The mechanism of strain effects on rotational property is investigated in theoretical level based on analytical model established through lattice dynamics theory. This work suggests great potentials of strain effects for nanoscale real-time control, and provides new ideas for design and application of real-time controllable nanoscale rotation system.

  13. Effects of Strain on Notched Zigzag Graphene Nanoribbons

    Directory of Open Access Journals (Sweden)

    Jack Baldwin

    2013-01-01

    Full Text Available The combined effects of an asymmetric (square or V-shaped notch and uniaxial strain are studied in a zigzag graphene nanoribbon (ZGNR device using a generalized tight-binding model. The spin-polarization and conductance-gap properties, calculated within the Landauer–B¨uttiker formalism, were found to be tunable for uniaxial strain along the ribbon-length and ribbon-width for an ideal ZGNR and square (V-shaped notched ZGNR systems. Uniaxial strain along the ribbon-width for strains 10% initiated significant notch-dependent reductions to the conduction-gap. For the V-shaped notch, such strains also induced spin-dependent changes that result, at 20% strain, in a semi-conductive state and metallic state for each respective spin-type, thus demonstrating possible quantum mechanisms for spin-filtration.

  14. Evolutionary perspective on the origin of Haitian cholera outbreak strain.

    Science.gov (United States)

    Dasgupta, Anirban; Banerjee, Rachana; Das, Santasabuj; Basak, Surajit

    2012-01-01

    Cholera epidemic has not been reported in Haiti for at least 100 years, although cholera has been present in Latin America since 1991. Surprisingly, the recent cholera epidemic in Haiti (October 2010) recorded more than 250,000 cases and 4000 deaths in the first 6 months and became one of the most explosive and deadly cholera outbreak in recent history. In the present study, we conducted genomic analyses of pathogenicity islands of three Haitian Vibrio cholerae strains and compared them with nine different V. cholerae O1 El Tor genomes. Although CIRS101 is evolutionarily most similar to the Haitian strains, our study also provides some important differences in the genetic organization of pathogenicity islands of Haitian strains with CIRS101. Evolutionary analysis suggests that unusual functional constraints have been imposed on the Haitian strains and we hypothesize that amino acid substitution is more deleterious in Haitian strains than in nonHaitian strains.

  15. Strain-induced negative differential resistance in ultrasmall carbon nanotube

    Science.gov (United States)

    Fang, Hui; Zhang, Fei-Peng; Ruan, Xing-Xiang; Huang, Can-Sheng; Jiang, Zhi-Nian; Peng, Jin-Yun; Wang, Ru-Zhi

    2017-08-01

    The transport properties in ultrasmall single-wall carbon nanotubes (SWCNTs) under tensile strain have been theoretically investigated. The regular negative differential resistance (NDR) induced by the strain undergoes a process from enhancement to weakening in the zigzag (3,0) SWCNT. The NDR achieves maximum with applying 4% tensile strain. Compared to the case of (3,0) SWCNT, that NDR cannot be manipulated by applying strain clearly in (4,0) and (5,0) ultrasmall SWCNTs with tensile strain lower than 10%. It proposes this strain-induced NDR effect to demonstrate the possibility of finding potential applications in SWCNT-based NDR nanodevices such as in memory devices, oscillators and fast switching devices.

  16. Genetic engineering of industrial strains of Saccharomyces cerevisiae.

    Science.gov (United States)

    Le Borgne, Sylvie

    2012-01-01

    Genetic engineering has been successfully applied to Saccharomyces cerevisiae laboratory strains for different purposes: extension of substrate range, improvement of productivity and yield, elimination of by-products, improvement of process performance and cellular properties, and extension of product range. The potential of genetically engineered yeasts for the massive production of biofuels as bioethanol and other nonfuel products from renewable resources as lignocellulosic biomass hydrolysates has been recognized. For such applications, robust industrial strains of S. cerevisiae have to be used. Here, some relevant genetic and genomic characteristics of industrial strains are discussed in relation to the problematic of the genetic engineering of such strains. General molecular tools applicable to the manipulation of S. cerevisiae industrial strains are presented and examples of genetically engineered industrial strains developed for the production of bioethanol from lignocellulosic biomass are given.

  17. Biaxial Compressive Strain Engineering in Graphene/Boron Nitride Heterostructures

    Science.gov (United States)

    Pan, Wei; Xiao, Jianliang; Zhu, Junwei; Yu, Chenxi; Zhang, Gang; Ni, Zhenhua; Watanabe, K.; Taniguchi, T.; Shi, Yi; Wang, Xinran

    2012-11-01

    Strain engineered graphene has been predicted to show many interesting physics and device applications. Here we study biaxial compressive strain in graphene/hexagonal boron nitride heterostructures after thermal cycling to high temperatures likely due to their thermal expansion coefficient mismatch. The appearance of sub-micron self-supporting bubbles indicates that the strain is spatially inhomogeneous. Finite element modeling suggests that the strain is concentrated on the edges with regular nano-scale wrinkles, which could be a playground for strain engineering in graphene. Raman spectroscopy and mapping is employed to quantitatively probe the magnitude and distribution of strain. From the temperature-dependent shifts of Raman G and 2D peaks, we estimate the TEC of graphene from room temperature to above 1000K for the first time.

  18. Environment Identification in Flight using Sparse Approximation of Wing Strain

    CERN Document Server

    Manohar, Krithika; Kutz, J Nathan

    2016-01-01

    This paper addresses the problem of identifying different flow environments from sparse data collected by wing strain sensors. Insects regularly perform this feat using a sparse ensemble of noisy strain sensors on their wing. First, we obtain strain data from numerical simulation of a Manduca sexta hawkmoth wing undergoing different flow environments. Our data-driven method learns low-dimensional strain features originating from different aerodynamic environments using Proper Orthogonal Decomposition (POD) modes in the frequency domain, and leverages compressed sensing and sparse approximation to classify a set of strain frequency signatures using a dictionary of POD modes. This bio-inspired machine learning architecture for dictionary learning and sparse classification permits fewer costly physical strain sensors while being simultaneously robust to sensor noise. A sensor placement algorithm identifies the frequency samples that best separate the different aerodynamic environments in rank-reduced POD feature...

  19. Strain sensitivity of band gaps of Sn-containing semiconductors

    DEFF Research Database (Denmark)

    Li, Hong; Castelli, Ivano Eligio; Thygesen, Kristian Sommer

    2015-01-01

    Tuning of band gaps of semiconductors is a way to optimize materials for applications within photovoltaics or as photocatalysts. One way to achieve this is through applying strain to the materials. We investigate the effect of strain on a range of Sn-containing semiconductors using density...... functional theory and many-body perturbation theory calculations. We find that the band gaps of bulk Sn oxides with SnO6 octahedra are highly sensitive to volumetric strain. By applying a small isotropic strain of 2% (-2%), a decrease (increase) of band gaps as large as 0.8 to 1.0 eV are obtained. We...... attribute the ultrahigh strain sensitivity to the pure Sn s-state character of the conduction-band edges. Other Sn-containing compounds may show both increasing and decreasing gaps under tensile strain and we show that the behavior can be understood by analyzing the role of the Sn s states in both...

  20. Strain effects on valence bands of wurtzite ZnO

    Science.gov (United States)

    Qiao, LiPing; Chai, ChangChun; Jin, Zhao; Yang, YinTang; Ma, ZhenYang

    2013-09-01

    Based on the k.p theory of Luttinger-Kohn and Bir-Pikus, analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained. Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed. In comparison with unstrained ZnO materials, apparent movement of valence band edges such as "light hole band", "heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials. Moreover, effective masses of "light hole band", "heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given. The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.

  1. "Behaviour changes in Permethrin-resistant strain of Anopheles Stephensi "

    Directory of Open Access Journals (Sweden)

    Vatandoost H

    2000-09-01

    Full Text Available Behaviour studies indicated that the permethrin resistant strin of An. Stephensi was 3-fold resistant to knock-down compared with the susceptible strain. The resistant strain was however 3-fold less irritable to permethrin and less responsive than the susceptible strain to the movement of an aspirator. If reduced irritability and reduced responsiveness to catch are consequences of the changes in the nervous system, then such a form of resistance may be disadvantageous to mosquitoes in natural populations.

  2. Strain Hardening of Polymer Glasses: Entanglements, Energetics, and Plasticity

    OpenAIRE

    Hoy, Robert S.; Robbins, Mark O.

    2007-01-01

    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are ...

  3. The Attenuation of Torsional Strain Wave in a PMMA Rod

    OpenAIRE

    田辺, 裕治; 前川, 一郎; 半田, 晋一; 原, 利昭; Tanabe, Yuji; Maekawa, Ichiro; Handa, Shinichi; Hara, Toshiaki

    1990-01-01

    In order to clarify the strain attenuation during shear wave propagation, impact torsion experiments are carried out using a PMMA rod specimen. The strain pulses measured by strain gages are complicated due to the superposition of many reflected and transmitted waves from the supported end of the specimen. To obtain data from such pulses for determining a viscoelastic model, a method which modifies the pulse form is developed taking into account wave propagation behavior in the experimental s...

  4. The development of a surface acoustic wave strain sensor

    OpenAIRE

    Donohoe, Brian

    2011-01-01

    Multi sensors networks are becoming increasingly prevalent in modern engineering applications. In multi sensor networks, wireless sensors are preferred over traditional wired methods. Sensors based upon the surface acoustic wave resonators (SAWR) are often identified as a potential candidate to act as wireless and passive strain sensors. This thesis details the design, fabrication, modelling, calibration and packaging of SAW strain sensors as a general purpose modular strain sensor. The motiv...

  5. Fiber-Optic Strain Sensors With Linear Characteristics

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1993-01-01

    Fiber-optic modal domain strain sensors having linear characteristics over wide range of strains proposed. Conceived in effort to improve older fiber-optic strain sensors. Linearity obtained by appropriate choice of design parameters. Pattern of light and dark areas at output end of optical fiber produced by interference between electromagnetic modes in which laser beam propagates in fiber. Photodetector monitors intensity at one point in pattern.

  6. Studies on probiotics properties of two lactobacillus strains

    OpenAIRE

    María Antonieta Brizuela; Paulina Serrano; Yovanka Pérez

    2001-01-01

    "In vitro" studies were carried out for the selection of Lactobacillus strains with probiotics characteristics. Two strains of Lactobacillus were evaluated for the growth specific rate, generation time, acids, bile and antimicrobial resistances. "In vitro" tests indicated that the strains presented a potential for being used as probiotics.Foram realizados estudos "in vitro" para selecionar cepas de Lactobacillus com características probióticas. Duas cepas de Lactobacillus foram avaliadas quan...

  7. Microscopic Origin of Strain Hardening in Methane Hydrate

    OpenAIRE

    Jihui Jia; Yunfeng Liang; Takeshi Tsuji; Sumihiko Murata; Toshifumi Matsuoka

    2016-01-01

    It has been reported for a long time that methane hydrate presents strain hardening, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain hardening only if the hydrate is confined to ...

  8. Effects of Value Strains on Psychopathology of Chinese Rural Youths

    OpenAIRE

    Zhang, Jie; Zhao, Sibo

    2013-01-01

    The Strain Theory of Suicide postulates that psychological strains usually precede mental disorders including suicidal behavior. This paper focuses on the effect of conflicting social value strains on the individual’s psychopathology. We analyzed the data of 2,031 respondents who were proxy informants for suicides and community living controls in a large scale psychological autopsy study in rural China, with the CES-D depression measure for the psychopathology. Individuals having experienced ...

  9. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    Energy Technology Data Exchange (ETDEWEB)

    Shvartz, A., E-mail: andrew.shvartz@mail.ioffe.ru; Samsonov, A.; Dreiden, G.; Semenova, I. [Ioffe Institute, 26 Politekhnicheskaya, St Petersburg 194021 (Russian Federation)

    2015-10-28

    Bulk strain solitary waves in nonlinearly elastic thin-walled cylindrical shells with variable geometrical and physical parameters are studied, and equation for the longitudinal strain component with the variable coefficients is derived. A conservative finite difference scheme is proposed, and the results of numerical simulation of the strain soliton evolution in a shell with the abrupt variations of cross section and physical properties of the material are presented.

  10. Characterisation of Bacillus thuringiensis kurstaki strains by toxicity ...

    African Journals Online (AJOL)

    SERVER

    2007-08-06

    Aug 6, 2007 ... Table 1. Flagella serotype and growth pattern of four Btk strains. Growth pattern. Strain. Flagellar serotype ak (h-1). Ag (h). Btk HD73. 3a3b3c. 1.05. 0.42. Btk HD1. 3a3b3c ... rate and generation time for other strains were within the. Kashyap and Amla 1823 .... Afr. J. Biotechnol. stranded DNA intermediate.

  11. Analysis of an asymmetric two-strain dengue model.

    Science.gov (United States)

    Kooi, Bob W; Aguiar, Maíra; Stollenwerk, Nico

    2014-02-01

    In this paper we analyse a two-strain compartmental dengue fever model that allows us to study the behaviour of a Dengue fever epidemic. Dengue fever is the most common mosquito-borne viral disease of humans that in recent years has become a major international public health concern. The model is an extension of the classical compartmental susceptible-infected-recovered (SIR) model where the exchange between the compartments is described by ordinary differential equations (ode). Two-strains of the virus exist so that a primary infection with one strain and secondary infection by the other strain can occur. There is life-long immunity to the primary infection strain, temporary cross-immunity and after the secondary infection followed by life-long immunity, to the secondary infection strains. Newborns are assumed susceptible. Antibody Dependent Enhancement (ade) is a mechanism where the pre-existing antibodies to the previous dengue infection do not neutralize but rather enhance replication of the secondary strain. In the previously studied models the two strains are identical with respect to their epidemiological functioning: that is the epidemiological process parameters of the two strains were assumed equal. As a result the mathematical model possesses a mathematical symmetry property. In this manuscript we study a variant with epidemiological asymmetry between the strains: the force of infection rates differ while all other epidemiological parameters are equal. Comparison with the results for the epidemiologically symmetric model gives insight into its robustness. Numerical bifurcation analysis and simulation techniques including Lyapunov exponent calculation will be used to study the long-term dynamical behaviour of the model. For the single strain system stable endemic equilibria exist and for the two-strain system endemic equilibria, periodic solutions and also chaotic behaviour. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Distribution of Bacillus thuringiensis strains in Southern Sweden.

    Science.gov (United States)

    Landén, R; Bryne, M; Abdel-Hameed, A

    1994-01-01

    Bacillus thuringiensis strains were found to be naturally present in the soils of southern Sweden, being isolated from nine out of 12 sites examined. Forest soil samples were more rich in B. thuringiensis strains than soil samples collected from cultivated areas. A wide diversity of B. thuringiensis strains, representing different biochemical groups, was isolated; samples from Aspö and Fogdö regions showed the highest degree of diversity.

  13. Strain-tuning of edge magnetism in zigzag graphene nanoribbons.

    Science.gov (United States)

    Yang, Guang; Li, Baoyue; Zhang, Wei; Ye, Miao; Ma, Tianxing

    2017-09-13

    Using the determinant quantum Monte-Carlo method, we elucidate the strain tuning of edge magnetism in zigzag graphene nanoribbons. Our intensive numerical results show that a relatively weak Coulomb interaction may induce a ferromagnetic-like behaviour with a proper strain, and the edge magnetism can be enhanced greatly as the strain along the zigzag edge increases, which provides another way to control graphene magnetism even at room temperature.

  14. Resistance fail strain gage technology as applied to composite materials

    Science.gov (United States)

    Tuttle, M. E.; Brinson, H. F.

    1985-01-01

    Existing strain gage technologies as applied to orthotropic composite materials are reviewed. The bonding procedures, transverse sensitivity effects, errors due to gage misalignment, and temperature compensation methods are addressed. Numerical examples are included where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain measurement errors.

  15. Genotypic comparison of Pantoea agglomerans plant and clinical strains

    Directory of Open Access Journals (Sweden)

    Frey Jürg E

    2009-09-01

    Full Text Available Abstract Background Pantoea agglomerans strains are among the most promising biocontrol agents for a variety of bacterial and fungal plant diseases, particularly fire blight of apple and pear. However, commercial registration of P. agglomerans biocontrol products is hampered because this species is currently listed as a biosafety level 2 (BL2 organism due to clinical reports as an opportunistic human pathogen. This study compares plant-origin and clinical strains in a search for discriminating genotypic/phenotypic markers using multi-locus phylogenetic analysis and fluorescent amplified fragment length polymorphisms (fAFLP fingerprinting. Results Majority of the clinical isolates from culture collections were found to be improperly designated as P. agglomerans after sequence analysis. The frequent taxonomic rearrangements underwent by the Enterobacter agglomerans/Erwinia herbicola complex may be a major problem in assessing clinical associations within P. agglomerans. In the P. agglomerans sensu stricto (in the stricter sense group, there was no discrete clustering of clinical/biocontrol strains and no marker was identified that was uniquely associated to clinical strains. A putative biocontrol-specific fAFLP marker was identified only in biocontrol strains. The partial ORF located in this band corresponded to an ABC transporter that was found in all P. agglomerans strains. Conclusion Taxonomic mischaracterization was identified as a major problem with P. agglomerans, and current techniques removed a majority of clinical strains from this species. Although clear discrimination between P. agglomerans plant and clinical strains was not obtained with phylogenetic analysis, a single marker characteristic of biocontrol strains was identified which may be of use in strain biosafety determinations. In addition, the lack of Koch's postulate fulfilment, rare retention of clinical strains for subsequent confirmation, and the polymicrobial nature of P

  16. Low-temperature strain gauges based on silicon whiskers

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2008-08-01

    Full Text Available To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

  17. EDITORIAL: Excelling under strain: band engineering in nanomaterials Excelling under strain: band engineering in nanomaterials

    Science.gov (United States)

    Demming, Anna

    2013-08-01

    A little stress or strain has been known to improve the performance of athletes, actors and of course nanomaterials alike. In fact strain in silicon is now a major engineering tool for improving the performance of devices, and is ubiquitously used in device design and fabrication. Strain engineering alters a material's band structure, a model of electron behaviour that describes how as atoms come together in a solid, their discrete electron orbitals overlap to ultimately give rise to bands of allowed energy levels. In a strained crystal lattice of silicon or silicon germanium the distance between atoms in the lattice is greater than usual and the bands of allowed energy levels change. This July marks 100 years since Bohr submitted his paper 'On the constitution of atoms and molecules' [1] where he describes the structure of the atom in terms of discrete allowed energy levels. The paper was a seminal contribution to the development of quantum mechanics and laid the initial theoretical precepts for band gap engineering in devices. In this issue Nrauda and a collaboration of researchers in Europe and Australia study the growth of defect-free SiGe islands on pre-patterned silicon [2]. They analyse the strain in the islands and determine at what point lattice dislocations set in with a view to informing implementation of strain engineering in devices. The effects of strain on band structure in silicon and germanium were already studied and reported in the 1950s [3, 4]. Since then the increasing focus on nanoscale materials and the hunger for control of electronic properties has prompted further study of strain effects. The increased surface area to volume ratio in nanostructures changes the strain behaviour with respect to bulk materials, and this can also be exploited for handling and fine tuning strain to manipulate material properties. It is perhaps no surprise that graphene, one of the most high-profile materials in current nanotechnology research, has attracted

  18. Modeling of a Surface Acoustic Wave Strain Sensor

    Science.gov (United States)

    Wilson, W. C.; Atkinson, Gary M.

    2010-01-01

    NASA Langley Research Center is investigating Surface Acoustic Wave (SAW) sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC) reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasite substrate. The results of the model of a SAW Strain Sensor on Langasite are presented

  19. Wireless Passive Strain Sensor Based on Surface Acoustic Wave Devices

    Directory of Open Access Journals (Sweden)

    T. Nomura

    2008-04-01

    Full Text Available Surface acoustic wave (SAW devices offer many attractive features for applications as chemical and physical sensors. In this paper, a novel SAW strain sensor that employs SAW delay lines has been designed. Two crossed delay lines were used to measure the two-dimensional strain. A wireless sensing system is also proposed for effective operation of the strain sensor. In addition, an electronic system for accurately measuring the phase characteristics of the signal wave from the passive strain sensor is proposed.

  20. Determination of band offsets in strained-Si heterolayers

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, C.K.; Samanta, S.K.; Chatterjee, S.; Dalapati, G.K.; Bhattacharya, S.; Armstrong, B.M.; Gamble, H.S.; McCarthy, J.; Perova, T.S.; Moore, R.A

    2004-09-01

    Strained-Si/SiGe/Si structures are of increasing importance for microelectronic applications. A fully relaxed-SiGe buffer layer is required for growing strained-Si for applications towards high performance field effect transistors (FETs) having strained-Si as the channel. Preparation of epitaxial strained-Si layers on relaxed-SiGe (001) heterostructures using low pressure chemical vapor deposition (LPCVD) is reported. Gas source molecular beam epitaxy (GSMBE) grown strained-Si films are used to compare with LPCVD strained-Si films. Characterization of the strained-Si layers has been performed using AFM, TEM and Raman spectroscopy. Conduction and valence band offsets of strained-Si on relaxed-SiGe heterostructures have been extracted from measured capacitance-voltage (C-V) profiling of MOS capacitors fabricated on strained-Si using SiO{sub 2} as the dielectric. Extracted experimental values of the valence and conduction band offsets are in good agreement with theoretical predictions.

  1. The measurement of the modal strain fields using digital shearography

    National Research Council Canada - National Science Library

    Lopes, H; Ribeiro, J.E; Vaz, M; Gomes, J.M

    2010-01-01

    This work presents a Michelson shearography interferometer configuration associated with stroboscopic double illumination technique for the measurement of modal rotation fields and their strain fields...

  2. Strain-level diversity of secondary metabolism in Streptomyces albus.

    Directory of Open Access Journals (Sweden)

    Ryan F Seipke

    Full Text Available Streptomyces spp. are robust producers of medicinally-, industrially- and agriculturally-important small molecules. Increased resistance to antibacterial agents and the lack of new antibiotics in the pipeline have led to a renaissance in natural product discovery. This endeavor has benefited from inexpensive high quality DNA sequencing technology, which has generated more than 140 genome sequences for taxonomic type strains and environmental Streptomyces spp. isolates. Many of the sequenced streptomycetes belong to the same species. For instance, Streptomyces albus has been isolated from diverse environmental niches and seven strains have been sequenced, consequently this species has been sequenced more than any other streptomycete, allowing valuable analyses of strain-level diversity in secondary metabolism. Bioinformatics analyses identified a total of 48 unique biosynthetic gene clusters harboured by Streptomyces albus strains. Eighteen of these gene clusters specify the core secondary metabolome of the species. Fourteen of the gene clusters are contained by one or more strain and are considered auxiliary, while 16 of the gene clusters encode the production of putative strain-specific secondary metabolites. Analysis of Streptomyces albus strains suggests that each strain of a Streptomyces species likely harbours at least one strain-specific biosynthetic gene cluster. Importantly, this implies that deep sequencing of a species will not exhaust gene cluster diversity and will continue to yield novelty.

  3. Nuclear magnetic resonance probe head design for precision strain control

    Science.gov (United States)

    Kissikov, T.; Sarkar, R.; Bush, B. T.; Lawson, M.; Canfield, P. C.; Curro, N. J.

    2017-10-01

    We present the design and construction of an NMR probe to investigate single crystals under strain at cryogenic temperatures. The probe head incorporates a piezoelectric-based apparatus from Razorbill Instruments that enables both compressive and tensile strain tuning up to strain values on the order of 0.3% with a precision of 0.001%. 75As NMR in BaFe2As2 reveals large changes to the electric field gradient and indicates that the strain is homogeneous to within 16% over the volume of the NMR coil.

  4. Identification of diarrheagenic Escherichia coli strains from avian organic fertilizers.

    Science.gov (United States)

    Puño-Sarmiento, Juan; Gazal, Luis Eduardo; Medeiros, Leonardo P; Nishio, Erick K; Kobayashi, Renata K T; Nakazato, Gerson

    2014-08-28

    The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC) strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%), three strains as Shiga toxin-producing (STEC; 4.7%), 10 strains as enteroaggregative (EAEC; 12.5%), but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections.

  5. Biodegradation of endosulfan by mixed bacteria culture strains of ...

    African Journals Online (AJOL)

    Biodegradation of endosulfan by mixed bacteria culture strains of Pseudomonas aeruginosa and Staphylococcus aureus. Nsidibeabasi Calvin Nwokem, Calvin Onyedika Nwokem, Casmir Emmanuel Gimba, Beatrice Nkiruka Iwuala ...

  6. Analysis of 3D strain in the human medial meniscus.

    Science.gov (United States)

    Kolaczek, S; Hewison, C; Caterine, S; Ragbar, M X; Getgood, A; Gordon, K D

    2016-10-01

    This study presents a method to evaluate three-dimensional strain in meniscal tissue using medical imaging. Strain is calculated by tracking small teflon markers implanted within the meniscal tissue using computed tomography imaging. The results are presented for strains in the middle and posterior third of the medial menisci of 10 human cadaveric knees, under simulated physiologically relevant loading. In the middle position, an average compressive strain of 3.4% was found in the medial-lateral direction, and average tensile strains of 1.4% and 3.5% were found in the anterior-posterior and superior-inferior directions respectively at 5° of knee flexion with an applied load of 1× body weight. In the posterior position, under the same conditions, average compressive strains of 2.2% and 6.3% were found in the medial-lateral and superior-inferior directions respectively, and an average tensile strain of 3.8% was found in the anterior-posterior direction. No statistically significant difference between strain in the middle or posterior of the meniscus or between the global strains is uncovered. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Influence of pore pressure change on coseismic volumetric strain

    Science.gov (United States)

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-01-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  8. Straining Graphene by Chemical Vapour Deposition Growth on Copper

    OpenAIRE

    Yu, Victor; Whiteway, Eric; Maassen, Jesse; Hilke, Michael

    2011-01-01

    Strain can be used as an alternate way to tune the electronic properties of graphene. Here we demonstrate that it is possible to tune the uniform strain of graphene simply by changing the chemical vapor deposition growth temperature of graphene on copper. Due to the cooling of the graphene on copper system, we can induce a uniform compressive strain on graphene. The strain is analyzed by Raman spectroscopy, where a shift in the 2D peak is observed and compared to our ab initio calculations of...

  9. Molecular characterisation of Xanthomonas strains isolated from aroids in Mauritius.

    Science.gov (United States)

    Khoodoo, M H R; Sahin, F; Donmez, M F; Fakim, Y Jaufeerally

    2005-06-01

    Mauritius is one of the largest world producers of Anthurium cut flowers but outbreaks of bacterial blight have never been reported on the island. This work was about the characterisation and identification of bacterial strains isolated from Anthurium andreanum, Dieffenbachia maculata and Aglaonema simplex in Mauritius. Fifteen strains, that showed the morphological properties of Xanthomonas on conventional media, were tested on two semi-selective media (Esculin-trehalose and cellobiose-starch). ELISA tests using a panel of monoclonal antibodies were carried out and three out of 15 strains reacted with a Xanthomonas-specific monoclonal antibody (MAb XII). Analysis using four sets of ribosomal primers revealed that the same three Mauritius strains shared conserved PCR products with reference xanthomonads including virulent strains of Xanthomonas axonopodis pv. dieffenbachiae (Xad). BIOLOG tests and the Sherlock Microbial Identification system (MIDI) identified these three new strains at the species level as X. axonopodis. The complementary tests that were carried out clearly confirmed that the three strains are xanthomonads and, moreover, a DNA probe which showed specificity to Xad strains suggested that the three Mauritius strains are non-virulent forms of the pathogen causing Anthurium blight.

  10. Research on Fatigue Strain and Fatigue Modulus of Concrete

    Directory of Open Access Journals (Sweden)

    Fangping Liu

    2017-01-01

    Full Text Available Concrete fatigue strain and fatigue modulus evolution play a vital role in the evaluation of the material properties. In this paper, by analyzing the advantages and disadvantages of existing concrete strain analysis methods, the level-S nonlinear fatigue strain model was proposed. The parameters’ physical meaning, the ranges, and the impact on the shape of the curve were all discussed. Then, the evolution model of fatigue modulus was established based on the fatigue strain evolution model and the hypothesis of fatigue modulus inversely related fatigue strain amplitude. The results indicate that the level-S model covered all types of fatigue strain evolution. It is very suitable for the description of strain evolution of concrete for its strong adaptability and high accuracy. It was found that the fitting curves coincided with the experimental curves very well, and the correlation coefficients were all above 0.98. The evolution curves of fatigue strain modulus both have three stages, namely, variation phase, linear change stage, and convergence stage. The difference is that the fatigue strain evolution curve is from the lower left corner to the upper right corner, but the fatigue modulus evolution curve is from the upper left corner to the right lower corner.

  11. A novel strain of porcine deltacoronavirus in Vietnam.

    Science.gov (United States)

    Le, Van Phan; Song, Sok; An, Byung-Hyun; Park, Gyu-Nam; Pham, Ngoc Thach; Le, Dinh Quyen; Nguyen, Van Tam; Vu, Thi Thu Hang; Kim, Ki-Sun; Choe, SeEun; An, Dong-Jun

    2018-01-01

    Two porcine deltacoronavirus (PDCoV) strains (Binh21 and HaNoi6) were isolated from two pig farms in North Vietnam. Phylogenetic analysis of the complete genomes and the Spike and Membrane genes revealed that the two Vietnam PDCoVs belong to the same lineage as PDCoVs from Thailand and Laos; however, the N genes belonged to the same lineage as PDCoVs from the USA, Korea, China, and Hong Kong. The recombination detection program subsequently identified the major parent (S5011 strain) and minor parent (HKU15-44 strain) of the two Vietnam PDCoV strains (p < 0.01).

  12. [Integrons and antimicrobial resistance gene cassettes in Shigella flexneri strains ].

    Science.gov (United States)

    Muñoz, Jeannette; Bello, Helia; Domínguez, Mariana; Mella, Sergio; Zemelman, Raúl; González, Gerardo

    2003-07-01

    The resistance of Shigella flexneri to antimicrobial agents can be associated to the presence of integrons that may contain and express antimicrobial resistance gene cassettes. To study antimicrobial resistance and the presence of integrons and antimicrobial gene cassettes in Shigella flexneri strains. In vitro susceptibility to 27 antimicrobials was studied in twenty four Shigella flexneri strains isolated from stools. The presence of integrons class 1, 2 and 3 and antimicrobial resistance gene cassettes was investigated by polymerase chain reaction (PCR) using specific primers for each gene. Most strains were resistant to one of the following antimicrobials: ampicillin, sulphonamide, trimethoprim, tetracycline, streptomycin, sulfamethoxazole-trimethoprim or chloramphenicol. Twenty nine percent were simultaneously resistant to all these antimicrobials. Integrons class 1 and 2 were found in 19 strains (79%). Class 3 integrons were not found. Gene cassettes dfrA1 and ant(3")I were associated to integrons class 2 in most strains (15/20, 75%). Genes cat, tetB and blarTEM were detected in 18/24 (75%), 7/24 (29%) and 4/24 (17%) of the strains, respectively and were not associated to any of the studied integrons. Genes that codify enzymes AAC(6')Ib and APH(3')VI were not detected in any strain. The high frequency of integrons found in the studied strains, could partly explain the increasing antimicrobial resistance of Shigella flexneri strains, isolated in Chile.

  13. Identification of Diarrheagenic Escherichia coli Strains from Avian Organic Fertilizers

    Directory of Open Access Journals (Sweden)

    Juan Puño-Sarmiento

    2014-08-01

    Full Text Available The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%, three strains as Shiga toxin-producing (STEC; 4.7%, 10 strains as enteroaggregative (EAEC; 12.5%, but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections.

  14. Influence of pore pressure change on coseismic volumetric strain

    Science.gov (United States)

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-10-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  15. Design and Construction of Strain Gauge Interface Pressure ...

    African Journals Online (AJOL)

    Design and Construction of Strain Gauge Interface Pressure Transducer for Measurement of Static and Dynamic Interface Pressure Applied by Pressure Garments and its Relationship to Deep Vein Thrombosis.

  16. Characterization Of Biaxial Strain Of Poly(L-Lactide) Tubes

    DEFF Research Database (Denmark)

    Løvdal, Alexandra Liv Vest; Andreasen, Jens Wenzel; Mikkelsen, Lars Pilgaard

    2016-01-01

    Poly(L-lactide) (PLLA) in its L-form has promising mechanical properties. Being a semi-crystalline polymer, it can be subjected to strain-induced crystallization at temperatures above Tg and can thereby become oriented. Following a simultaneous (SIM) biaxial strain process or a sequential (SEQ......) biaxial strain process, the mechanical properties of biaxial strained tubes can be further improved. This study investigated these properties in relation to their morphology and crystal orientation. Both processes yield the same mechanical strength and modulus, yet exhibit different crystal orientation...

  17. Strain gradient plasticity effects in whisker-reinforced metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2002-01-01

    A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (2001). Cell-model analyzes are used to study the influence of the material length parameters numerically. Different higher order boundary conditions are considered...... at the fiber-matrix interface. The results are presented as overall stress-strain curves for the whisker-reinforced metal, and also contour plots of effective plastic strain are shown. The strain gradient plasticity theory predicts a significant stiffening effect when compared to conventional models...

  18. Complete Genome Sequence of Escherichia coli Strain WG5

    DEFF Research Database (Denmark)

    Imamovic, Lejla; Misiakou, Maria-Anna; van der Helm, Eric

    2018-01-01

    Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain.......Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain....

  19. Isolation, identification and characterization of regional indigenous Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Šuranská, Hana; Vránová, Dana; Omelková, Jiřina

    2016-01-01

    In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir) were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic) wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines. Copyright © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  20. Isolation, identification and characterization of regional indigenous Saccharomyces cerevisiae strains

    Directory of Open Access Journals (Sweden)

    Hana Šuranská

    2016-03-01

    Full Text Available Abstract In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines.

  1. Identification of Bacillus strains for biological control of catfish pathogens.

    Science.gov (United States)

    Ran, Chao; Carrias, Abel; Williams, Malachi A; Capps, Nancy; Dan, Bui C T; Newton, Joseph C; Kloepper, Joseph W; Ooi, Ei L; Browdy, Craig L; Terhune, Jeffery S; Liles, Mark R

    2012-01-01

    Bacillus strains isolated from soil or channel catfish intestine were screened for their antagonism against Edwardsiella ictaluri and Aeromonas hydrophila, the causative agents of enteric septicemia of catfish (ESC) and motile aeromonad septicaemia (MAS), respectively. Twenty one strains were selected and their antagonistic activity against other aquatic pathogens was also tested. Each of the top 21 strains expressed antagonistic activity against multiple aquatic bacterial pathogens including Edwardsiella tarda, Streptococcus iniae, Yersinia ruckeri, Flavobacterium columnare, and/or the oomycete Saprolegnia ferax. Survival of the 21 Bacillus strains in the intestine of catfish was determined as Bacillus CFU/g of intestinal tissue of catfish after feeding Bacillus spore-supplemented feed for seven days followed by normal feed for three days. Five Bacillus strains that showed good antimicrobial activity and intestinal survival were incorporated into feed in spore form at a dose of 8×10(7) CFU/g and fed to channel catfish for 14 days before they were challenged by E. ictaluri in replicate. Two Bacillus subtilis strains conferred significant benefit in reducing catfish mortality (Pcatfish. Safety of the four strains exhibiting the strongest biological control in vivo was also investigated in terms of whether the strains contain plasmids or express resistance to clinically important antibiotics. The Bacillus strains identified from this study have good potential to mediate disease control as probiotic feed additives for catfish aquaculture.

  2. Spin Splitting and Spin Current in Strained Bulk Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-01-15

    We present a theory for two recent experiments in bulk strained semiconductors and show that a new, previously overlooked, strain spin-orbit coupling term may play a fundamental role. We propose simple experiments that could clarify the origin of strain-induced spin-orbit coupling terms in inversion asymmetric semiconductors. We predict that a uniform magnetization parallel to the electric field will be induced in the samples studied in for specific directions of the applied electric field. We also propose special geometries to detect spin currents in strained semiconductors.

  3. Evaluation of Brucella abortus strain RB51 and strain 19 in pronghorn antelope

    Science.gov (United States)

    Elzer, P.H.; Smith, J.; Roffe, T.; Kreeger, T.; Edwards, J.; Davis, D.

    2002-01-01

    Free-roaming elk and bison in the Greater Yellowstone Area remain the only wildlife reservoirs for Brucella abortus in the United States, and the large number of animals and a lack of holding facilities make it unreasonable to individually vaccinate each animal. Therefore, oral delivery is being proposed as a possible option to vaccinate these wild ungulates. One of the main problems associated with oral vaccination is the potential exposure of nontarget species to the vaccines. The purpose of this study was to determine the effects of two Brucella vaccines, strain 19 (S19) and the rough strain RB51 (SRB51), in pregnant pronghorn antelope. We conclude that S19 and SRB51 rarely colonize maternal and fetal tissues of pregnant pronghorn and were not associated with fetal death. Oral delivery of either vaccine at this dose appears to be nonhazardous to pregnant pronghorn.

  4. High Strain and Strain-Rate Behaviour of Ptfe/aluminuim/tungsten Mixtures

    Science.gov (United States)

    Addiss, John; Cai, Jing; Walley, Stephen; Proud, William; Nesterenko, Vitali

    2007-12-01

    Conventional drop-weight techniques were modified to accommodate low-amplitude force transducer signals from low-strength, cold isostatically pressed `heavy' composites of polytetrafluoroethylene, aluminum and tungsten (W). The failure strength, strain and the post-critical behavior of failed samples were measured for samples of different porosity and tungsten grain size. Unusual phenomenon of significantly higher strength (55 MPa) of porous composites (density 5.9 g/cm3) with small W particles (<1 μm) in comparison with strength (32 MPa) of dense composites (7.1 g/cm3) with larger W particles (44 μm) at the same volume content of components was observed. This is attributed to force chains created by a network of small W particles. Interrupted tests at different levels of strain revealed the mechanisms of fracture under dynamic compression.

  5. Draft genome sequences of eight bacteria isolated from the indoor environment: Staphylococcus capitis strain H36, S. capitis strain H65, S. cohnii strain H62, S. hominis strain H69, Microbacterium sp. strain H83, Mycobacterium iranicum strain H39, Plantibacter sp. strain H53, and Pseudomonas oryzihabitans strain H72.

    Science.gov (United States)

    Lymperopoulou, Despoina S; Coil, David A; Schichnes, Denise; Lindow, Steven E; Jospin, Guillaume; Eisen, Jonathan A; Adams, Rachel I

    2017-01-01

    We report here the draft genome sequences of eight bacterial strains of the genera Staphylococcus, Microbacterium, Mycobacterium, Plantibacter, and Pseudomonas. These isolates were obtained from aerosol sampling of bathrooms of five residences in the San Francisco Bay area. Taxonomic classifications as well as the genome sequence and gene annotation of the isolates are described. As part of the "Built Environment Reference Genome" project, these isolates and associated genome data provide valuable resources for studying the microbiology of the built environment.

  6. Improved hardware for higher spatial resolution strain-encoded (SENC) breast MRI for strain measurements.

    Science.gov (United States)

    Harouni, Ahmed A; Hossain, Jakir; Jacobs, Michael A; Osman, Nael F

    2011-06-01

    Early detection of breast lesions using mammography has resulted in lower mortality rates. However, some breast lesions are mammography occult, and magnetic resonance imaging (MRI) is recommended, but it has lower specificity. It is possible to achieve higher specificity by using strain-encoded (SENC) MRI and/or magnetic resonance elastography. SENC breast MRI can measure the strain properties of breast tissue. Similarly, magnetic resonance elastography is used to measure the elasticity (ie, shear stiffness) of different tissue compositions interrogating the tissue mechanical properties. Reports have shown that malignant tumors are three to 13 times stiffer than normal tissue and benign tumors. The investigators have developed a SENC breast hardware device capable of periodically compressing the breast, thus allowing for longer scanning time and measuring the strain characteristics of breast tissue. This hardware enables the use of SENC MRI with high spatial resolution (1 × 1 × 5 mm(3)) instead of fast SENC imaging. Simple controls and multiple safety measures were added to ensure accurate, repeatable, and safe in vivo experiments. Phantom experiments showed that SENC breast MRI has higher signal-to-noise ratio and contrast-to-noise ratio than fast SENC imaging under different scanning resolutions. Finally, the SENC breast device reproducibility measurements resulted in a difference of breast magnetic resonance images have higher signal-to-noise ratio and contrast-to-noise ratios than fast SENC images. Thus, combining SENC breast strain measurements with diagnostic breast MRI to differentiate benign from malignant lesions could potentially increase the specificity of diagnosis in the clinical setting. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  7. Compliant intracortical implants reduce strains and strain rates in brain tissue in vivo

    Science.gov (United States)

    Sridharan, Arati; Nguyen, Jessica K.; Capadona, Jeffrey R.; Muthuswamy, Jit

    2015-06-01

    Objective. The objective of this research is to characterize the mechanical interactions of (1) soft, compliant and (2) non-compliant implants with the surrounding brain tissue in a rodent brain. Understanding such interactions will enable the engineering of novel materials that will improve stability and reliability of brain implants. Approach. Acute force measurements were made using a load cell in n = 3 live rats, each with 4 craniotomies. Using an indentation method, brain tissue was tested for changes in force using established protocols. A total of 4 non-compliant, bare silicon microshanks, 3 non-compliant polyvinyl acetate (PVAc)-coated silicon microshanks, and 6 compliant, nanocomposite microshanks were tested. Stress values were calculated by dividing the force by surface area and strain was estimated using a linear stress-strain relationship. Micromotion effects from breathing and vascular pulsatility on tissue stress were estimated from a 5 s interval of steady-state measurements. Viscoelastic properties were estimated using a second-order Prony series expansion of stress-displacement curves for each shank. Main results. The distribution of strain values imposed on brain tissue for both compliant nanocomposite microshanks and PVAc-coated, non-compliant silicon microshanks were significantly lower compared to non-compliant bare silicon shanks. Interestingly, step-indentation experiments also showed that compliant, nanocomposite materials significantly decreased stress relaxation rates in the brain tissue at the interface (p brain tissue. Understanding the material behavior at the site of tissue contact will help to improve neural implant design.

  8. Conversion of the BASE prion strain into the BSE strain: the origin of BSE?

    Directory of Open Access Journals (Sweden)

    Raffaella Capobianco

    2007-03-01

    Full Text Available Atypical neuropathological and molecular phenotypes of bovine spongiform encephalopathy (BSE have recently been identified in different countries. One of these phenotypes, named bovine "amyloidotic" spongiform encephalopathy (BASE, differs from classical BSE for the occurrence of a distinct type of the disease-associated prion protein (PrP, termed PrP(Sc, and the presence of PrP amyloid plaques. Here, we show that the agents responsible for BSE and BASE possess different biological properties upon transmission to transgenic mice expressing bovine PrP and inbred lines of nontransgenic mice. Strikingly, serial passages of the BASE strain to nontransgenic mice induced a neuropathological and molecular disease phenotype indistinguishable from that of BSE-infected mice. The existence of more than one agent associated with prion disease in cattle and the ability of the BASE strain to convert into the BSE strain may have important implications with respect to the origin of BSE and spongiform encephalopathies in other species, including humans.

  9. Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

    2016-01-01

    Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

  10. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    OpenAIRE

    Wei Wang; Yan Ma; Muxin Yang; Ping Jiang; Fuping Yuan; Xiaolei Wu

    2017-01-01

    The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been ...

  11. Strain predominance following exposure of vaccinated and naive pregnant gilts to multiple strains of porcine reproductive and respiratory syndrome virus

    OpenAIRE

    Lager, Kelly M.; Mengeling, William L.; Wesley, Ronald D.

    2003-01-01

    Two studies were performed in order to test the relative ability of different strains of porcine reproductive and respiratory syndrome virus (PRRSV) to replicate and cross the placental barrier in pregnant gilts. Study 1 comprised 6 nonvaccinated gilts. Study 2 comprised 8 nonvaccinated gilts and 12 gilts that were vaccinated twice before conception. On, or about, gestation day 90 all gilts were simultaneously exposed to 20 field strains of PRRSV (all strains were distinguishable by restricti...

  12. Complete Genome Sequence of the Human Herpesvirus 6A Strain AJ from Africa Resembles Strain GS from North America.

    Science.gov (United States)

    Tweedy, J; Spyrou, M A; Donaldson, C D; Depledge, D; Breuer, J; Gompels, U A

    2015-02-12

    The genome sequence of human herpesvirus 6A (HHV-6A) strain AJ was determined in a comparison of target enrichment and long-range PCR using next-generation sequencing methodologies. The analyses show 85 predicted open reading frames (ORFs), conservation with sequenced HHV-6A reference strain U1102, and closest identity to the recently determined GS strain, despite different geographic origins (United States and Gambia). Copyright © 2015 Tweedy et al.

  13. Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

    Directory of Open Access Journals (Sweden)

    Oswald R Crasta

    Full Text Available The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study is to identify candidate virulence genes by systematic comparative analysis of the attenuated strain with the published genome sequences of two virulent and closely related strains of B. abortus, 9-941 and 2308. The two S19 chromosomes are 2,122,487 and 1,161,449 bp in length. A total of 3062 genes were identified and annotated. Pairwise and reciprocal genome comparisons resulted in a total of 263 genes that were non-identical between the S19 genome and any of the two virulent strains. Amongst these, 45 genes were consistently different between the attenuated strain and the two virulent strains but were identical amongst the virulent strains, which included only two of the 236 genes that have been implicated as virulence factors in literature. The functional analyses of the differences have revealed a total of 24 genes that may be associated with the loss of virulence in S19. Of particular relevance are four genes with more than 60 bp consistent difference in S19 compared to both the virulent strains, which, in the virulent strains, encode an outer membrane protein and three proteins involved in erythritol uptake or metabolism.

  14. Copeptin reflects physiological strain during thermal stress.

    Science.gov (United States)

    Stacey, Michael John; Delves, Simon K; Britland, Sophie E; Allsopp, Adrian J; Brett, Stephen J; Fallowfield, Joanne L; Woods, David R

    2018-01-01

    To prevent heat-related illnesses, guidelines recommend limiting core body temperature (T c) ≤ 38 °C during thermal stress. Copeptin, a surrogate for arginine vasopressin secretion, could provide useful information about fluid balance, thermal strain and health risks. It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect T c responses. Volunteers (n = 15) were recruited from a British Army unit deployed to East Africa. During a simulated combat assault (3.5 h, final ambient temperature 27 °C), T c was recorded by radiotelemetry to differentiate volunteers with maximum T c > 38 °C versus ≤ 38 °C. Blood was sampled beforehand and afterwards, for measurement of copeptin, cortisol, free normetanephrine, osmolality and creatinine. There was a significant (P copeptin from pre- to post-assault (10.0 ± 6.3 vs. 16.7 ± 9.6 pmol L-1, P copeptin correlated strongly with osmolality after the exposure (r = 0.70, P = 0.004). In volunteers with maximum T c > 38 °C (n = 8) vs ≤ 38 °C (n = 7) there were significantly greater elevations in copeptin (10.4 vs. 2.4 pmol L-1) and creatinine (10 vs. 2 μmol L-1), but no differences in cortisol, free normetanephrine or osmolality. Changes in copeptin reflected T c response more closely than sympathoadrenal markers or osmolality. Dynamic relationships with tonicity and kidney function may help to explain this finding. As a surrogate for integrated physiological strain during work in a field environment, copeptin assay could inform future measures to prevent heat-related illnesses.

  15. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-12-01

    Full Text Available The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness.

  16. Body fat distribution and organ weights of 14 common strains and a 22-strain consomic panel of rats.

    Science.gov (United States)

    Reed, Danielle R; Duke, Fujiko F; Ellis, Hillary K; Rosazza, Matthew R; Lawler, Maureen P; Alarcon, Laura K; Tordoff, Michael G

    2011-07-06

    The goal of this study was to determine the adiposity of a range of rat strains, including a panel of consomics, to estimate heritability. To that end, we assessed the body fat distribution and organ weights of groups of adult male rats from 3 outbred strains, 11 inbred strains and 22 consomic strains. We measured the weights of the gonadal, retroperitoneal, mesenteric, femoral, subscapular and pericardial white fat depots, the subscapular brown fat depot, the kidneys, liver, heart, spleen, and brain. Strains were compared for the measured weight of each of these adipose depots and organs, and also for these weights adjusted statistically for body size. All individual adipose depot and organ weights were highly heritable, in most cases h(2)>0.50. The fourteen inbred and outbred rat strains were not very different in body length but there was a three-fold difference in body weight, and up to a twenty-fold difference in the weight of some adipose depots. Comparison of the FHH-Chr n(BN) consomic strains with the FHH host strain revealed 98 quantitative trait loci (QTLs) for body composition and organ weight, with the introgressed chromosome reducing weight or adiposity in most cases. These results can be used to guide the choice of appropriate rat strains for future studies of the genetic architecture of obesity and body size. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. The Genetically Remote Pathogenic Strain NVH391-98 of the Bacillus cereus Group Represents the Cluster of Thermophilic Strains

    Energy Technology Data Exchange (ETDEWEB)

    Auger, Sandrine; Galleron, Nathalie; Bidnenko, Elena; Ehrlich, S. Dusko; Lapidus, Alla; Sorokin, Alexei

    2007-10-02

    Bacteria of the Bacillus cereus group are known to cause food poisoning. A rare phylogenetically remote strain, NVH391-98, was recently characterized to encode a particularly efficient cytotoxin K presumably responsible for food poisoning. This pathogenic strain and its close relatives can be phenotypically distinguished from other strains of the B. cereus group by the inability to grow at temperatures below 17 degrees C and by the ability to grow at temperatures from 48 to 53 degrees C. A temperate phage, phBC391A2, residing in the genome of NVH391-98 allows us to distinguish the three known members of this thermophilic strain cluster.

  18. Genetic analysis of Saccharomyces cerevisiae strains isolated from palm wine in eastern Nigeria. Comparison with other African strains.

    Science.gov (United States)

    Ezeronye, O U; Legras, J-L

    2009-05-01

    To study the yeast diversity of Nigerian palm wines by comparison with other African strains. Twenty-three Saccharomyces cerevisiae strains were obtained from palm wine samples collected at four locations in eastern Nigeria, and characterized using different molecular techniques: internal transcribed spacer restriction fragment length polymorphism and sequence analysis, pulsed field gel electrophoresis, inter delta typing and microsatellite multilocus analysis. These techniques revealed that palm wine yeasts represent a group of closely related strains that includes other West African isolates (CBS400, NCYC110, DVPG6044). Population analysis revealed an excess of homozygote strains and an allelic richness similar to wine suggestive of local domestication. Several other African yeast strains were not connected to this group. Ghana sorghum beer strains and other African strains (DBVPG1853 and MUCL28071) displayed strikingly high relatedness with European bread, beer or wine strains, and the genome of strain MUCL30909 contained African and wine-type alleles, indicating its hybrid origin. Nigerian palm wine yeast represents a local specific yeast flora, whereas a European origin or hybrid was suspected for several other Africa isolates. This study presents the first genetic characterization of an autochthonous African palm wine yeast population and confirms the idea that human intervention has favoured yeast migration.

  19. Cardiac biplane strain imaging: initial in vivo experience

    Science.gov (United States)

    Lopata, R. G. P.; Nillesen, M. M.; Verrijp, C. N.; Singh, S. K.; Lammens, M. M. Y.; van der Laak, J. A. W. M.; van Wetten, H. B.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

    2010-02-01

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (heart were recorded during the cardiac cycle in four dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve (Δp: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy (Δp = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

  20. Fumonisin and Ochratoxin Production in Industrial Aspergillus niger Strains

    Science.gov (United States)

    Frisvad, Jens C.; Larsen, Thomas O.; Thrane, Ulf; Meijer, Martin; Varga, Janos; Samson, Robert A.; Nielsen, Kristian F.

    2011-01-01

    Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains) as well as 228 strains from 17 related black Aspergillus species were examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B2, B4, and B6) were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also produced fumonisins. Strains optimized through random mutagenesis usually maintained their mycotoxin production capability. Toxigenic strains were also able to produce the toxins on media suggested for citric acid production with most of the toxins found in the biomass, thereby questioning the use of the remaining biomass as animal feed. In conclusion it is recommended to use strains of A. niger with inactive or inactivated gene clusters for fumonisins and ochratoxins, or to choose isolates for biotechnological uses in related non-toxigenic species such as A. tubingensis, A. brasiliensis, A vadensis or A. acidus, which neither produce fumonisins nor ochratoxins. PMID:21853139

  1. Fumonisin and ochratoxin production in industrial Aspergillus niger strains.

    Directory of Open Access Journals (Sweden)

    Jens C Frisvad

    Full Text Available Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe. However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains as well as 228 strains from 17 related black Aspergillus species were examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B(2, B(4, and B(6 were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also produced fumonisins. Strains optimized through random mutagenesis usually maintained their mycotoxin production capability. Toxigenic strains were also able to produce the toxins on media suggested for citric acid production with most of the toxins found in the biomass, thereby questioning the use of the remaining biomass as animal feed. In conclusion it is recommended to use strains of A. niger with inactive or inactivated gene clusters for fumonisins and ochratoxins, or to choose isolates for biotechnological uses in related non-toxigenic species such as A. tubingensis, A. brasiliensis, A vadensis or A. acidus, which neither produce fumonisins nor ochratoxins.

  2. Cardiac biplane strain imaging: initial in vivo experience

    Energy Technology Data Exchange (ETDEWEB)

    Lopata, R G P; Nillesen, M M; Thijssen, J M; De Korte, C L [Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Verrijp, C N; Lammens, M M Y; Van der Laak, J A W M [Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Singh, S K; Van Wetten, H B [Department of Cardiothoracic Surgery, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Kapusta, L [Pediatric Cardiology, Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)], E-mail: R.Lopata@cukz.umcn.nl

    2010-02-21

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (<100 Hz) using a commercial platform with an RF interface. For testing the method in vivo, biplane image sequences of the heart were recorded during the cardiac cycle in four dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve ({delta}p: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy ({delta}p = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

  3. Enterococcus faecium strains characterization through polymorphism study of VNTR loci

    Directory of Open Access Journals (Sweden)

    Belteghi, C.,

    2008-12-01

    Full Text Available Enterococci are commensally bacteria of the gastrointestinal and female genital tract in humans and some mammals and birds, and one of the significant causes of hospital-acquired infections, especially in immuno-compromised patients. Genetic fingerprinting (DNA fingerprinting is a tool for identifying, marking and prevention of infectious agents dissemination. SSR (short sequence repeat are known to suffer frequent variations in the number of repetitive units.MLVA (multiple locus variable number tandem repeats analysis is a variant of genetic fingerprinting, in epidemiological studies on the pathogenetic Enterococcus faecium. Our study included laboratory Enterococcus faecium strains or isolated from clinical cases or from the environment (2003-2008. All analyzed strains of Enterococcus faecium were sensitive to vancomycin, except BM4147, and resistant to oxacilin. Strains isolated from the birds’ samples have shown a smaller resistance profile than those of human origin. 33 Enterococus faecium strains were analyzed by PCR amplification. 27 MT (VNTR profiles were obtained: six in the case of the strains isolated from birds, 15 in the case of the strains isolated form humans, 4 in the case of the collection strains and 2 in the case of the strains isolated from water samples. Among the strains isolated from humans and those isolated from animals, identical profiles were not recorded. Within the strains isolated from clinical cases, and those isolated from birds, circulating genotypes were noted, which can be considered as epidemical. The strains used as probiotics proved to be different from those circulating in birds. All MLVA profiles codes compared with those published on line in the UMC Utrecht database proved to be different. Results obtained in this study support the usefulness of the polymorphic VNTR analysis, as genetic marker, inepidemiological investigations.

  4. Job strain in nursing homes - Exploring the impact of leadership.

    Science.gov (United States)

    Backman, Annica; Sjögren, Karin; Lövheim, Hugo; Edvardsson, David

    2017-11-17

    This study aimed to explore the association between leadership behaviours, job strain and social support as perceived by direct care staff in nursing homes. It is well known that aged care staff experience high levels of job strain, and that aged care staff experiencing job strain are exposed to increased risk for adverse health effects. Managerial leadership styles have been associated to job strain in the literature, however, the impact of perceived leadership behaviors' on staff job strain and social support has not been clarified within this context. This study had a cross-sectional design. Participating staff (n=3605) completed surveys which included questions about staff characteristics, valid and reliable measures of managerial leadership behaviors, perceived job strain and social support. Statistical analyses of correlations and multiple regression analysis with interaction terms were conducted. Highly rated leadership behaviors' were significantly associated to lower lever of job strain and higher level of social support. Higher levels of leadership behaviors' also moderated the impact of social support on job strain. Highly rated leadership behaviours in nursing home managers seems to buffer staff job strain and potentiate social support within nursing homes. Thus, nursing home managers' leadership behaviors seem beneficial for the working situation and strain of staff. Promoting a supporting work environment through a positive leadership seems to be an important implication for middle managers in nursing home care as it can influence staff perception of job strain and social support within the unit. By providing leadership, offering support and strategies towards a healthy work environment, nursing home managers may through their leadership, prevent adverse health effects among staff. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  5. Strain - The Heart of the Matter

    Science.gov (United States)

    Gapinski, Wendy R.

    2013-01-01

    Objective: Identify how much exercise is needed to maintain pre-bedrest / pre-spaceflight strength, minimize any flight complications and reduce time required to reacclimate to Earth's gravity. Subjects volunteered to participate in a 70 day 6deg head down tilt (HDT) study at UTMB hospital in Galveston. HDT are used to study microgravity for several reasons: 1. Allows subjects to experience atrophy of lower extremities from disuse. 2. Allows scientist to study the fluid shifts and the subject's cardiovascular and physiological effects. 3. Allows several studies to be measured and conducted simultaneously in a safe and monitored environment. Throughout those 10 weeks, subjects were either in an exercise or control group. Never before has cardiac strain been monitored at set time points throughout spaceflight or bed rest study. Once we clearly understand this technique, protocols can be formulated for astronauts to use on the ISS as both a diagnostic and monitoring tool. Echoes could have the possibility to predict & monitor heart health, cardiac strength, endurance, and overall rate of muscle degradation. Also, echoes can act as an additional factor in determining exercise prescriptions and effectiveness.

  6. Lipase activity from strains of Pasteurella multocida.

    Science.gov (United States)

    Pratt, J; Cooley, J D; Purdy, C W; Straus, D C

    2000-05-01

    Thirteen clinical isolates of Pasteurella multocida from a variety of different animals and humans were examined for their ability to produce lipase. Lipase substrates used included Tween 20, Tween 40, Tween 80, and Tween 85. Lipase activity was detected in the filtrates of organisms grown to the exponential phase in Roswell Park Memorial Institute-1640 defined media (RPMI-1640), but activity increased in the filtrates when the cultures were allowed to proceed to the stationary phase. All strains examined (except for serotype 2) showed lipase activity against at least one of the Tweens. Tween 40 was the best substrate to demonstrate lipase activity. Pasteurella multocida serotype 8 produced the most active lipase against Tween 40 (3,561.7 units of activity/microgram of protein). This activity continued to increase after P. multocida entered a stationary growth phase. P. multocida lipase activity was optimal at pH 8.0. Lipase activity of P. multocida serotype 8 was eluted from a Sepharose 2B column at several points, indicating that several lipases may be produced in vitro by this organism. These data demonstrate that clinical isolates of P. multocida produce lipase; therefore, this enzyme should be considered a potential virulence factors for this organism.

  7. Fatty acid profiling to characterize California strains of Xylella fastidiosa

    Science.gov (United States)

    Different strains of Xylella fastidiosa cause diseases such as Pierce’s disease of grapevine, citrus variegated chlorosis, and bacterial leaf scorch of hardwoods. However, more research is needed to better define subspecies and strains of X. fastidiosa to improve both regulations concerning this bac...

  8. Development of bioluminescent Salmonella strains for use in food safety

    Science.gov (United States)

    Karsi, Attila; Howe, Kevin; Kirkpatrick, Tasha B; Wills, Robert; Bailey, R Hartford; Lawrence, Mark L

    2008-01-01

    Background Salmonella can reside in healthy animals without the manifestation of any adverse effects on the carrier. If raw products of animal origin are not handled properly during processing or cooked to a proper temperature during preparation, salmonellosis can occur. In this research, we developed bioluminescent Salmonella strains that can be used for real-time monitoring of the pathogen's growth on food products. To accomplish this, twelve Salmonella strains from the broiler production continuum were transformed with the broad host range plasmid pAKlux1, and a chicken skin attachment model was developed. Results Salmonella strains carrying pAKlux1 constitutively expressed the luxCDABE operon and were therefore detectable using bioluminescence. Strains were characterized in terms of bioluminescence properties and plasmid stability. To assess the usefulness of bioluminescent Salmonella strains in food safety studies, we developed an attachment model using chicken skin. The effect of washing on attachment of Salmonella strains to chicken skin was tested using bioluminescent strains, which revealed the attachment properties of each strain. Conclusion This study demonstrated that bioluminescence is a sensitive and effective tool to detect Salmonella on food products in real-time. Bioluminescence imaging is a promising technology that can be utilized to evaluate new food safety measures for reducing Salmonella contamination on food products. PMID:18211715

  9. Antagonistic activity of selected strains of Bacillus thuringiensis ...

    African Journals Online (AJOL)

    The aim of this work was to determine, in vitro, the antagonistic effectiveness of 60 strains of Bacillus thuringiensis against damping-off and root and stem rot caused by Rhizoctonia solani. The strains were obtained from the International Collection of Entomopathogenic Bacillus at the FCB-UANL. During the in vitro dual ...

  10. Taxonomy of Streptomyces strains isolated from rhizospheres of ...

    African Journals Online (AJOL)

    This work was designed to identify and taxonomically classify Streptomyces strains isolated from the rhizospheres of various plant species; banana, rose, pomegranate and grape plants, having antagonistic activity against some microbial (bacteria and fungi) tissue culture contaminants. Streptomyces strains with the most ...

  11. Strain engineering of magnetic state in vacancy-doped phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jie [Hunan Provincial Key Laboratory of Micro–Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, Hunan (China); Zhang, Chunxiao, E-mail: zhangchunxiao@xtu.edu.cn [Hunan Provincial Key Laboratory of Micro–Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, Hunan (China); Li, Jin [Hunan Provincial Key Laboratory of Micro–Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, Hunan (China); Guo, Zhixin [Department of Physics, Xiangtan University, Xiangtan 411105, Hunan (China); Xiao, Huaping, E-mail: hpxiao@xtu.edu.cn [Hunan Provincial Key Laboratory of Micro–Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, Hunan (China); Zhong, Jianxin [Hunan Provincial Key Laboratory of Micro–Nano Energy Materials and Devices, Xiangtan University, Xiangtan 411105, Hunan (China)

    2016-09-23

    Inducing and manipulating the magnetism in two-dimensional materials play an important role for the development of the next-generation spintronics. In this letter, the effects of the biaxial strain on magnetic properties of vacancy-doped phosphorene are investigated using first-principles calculation. We find although only SV956 doping induces magnetism for unstrained phosphorene, the biaxial strain induces nonzero magnetic moment for SV5566 and DVa doped phosphorene. The biaxial strain also modulates the magnetic state for SV956, SV5566 and DVa doped phosphorene. The local magnetic moment derives from the spin polarization of the dangling bonds near the vacancy. The biaxial strain influences the local bonding configuration near the vacancy which determines the presence of dangling bonds, and then modulates the magnetic state. Our findings promise the synergistic effect of strain engineering and vacancy decoration is an effective method for the operation of phosphorene-based spintronic devices. - Highlights: • Investigation of the magnetic moment of vacancy-doped phosphorene by DFT calculation. • The modulation of the magnetic moment by the biaxial strain. • The analysis of the bonding configuration with the biaxial strain. • The analysis of the electronic structures to explain the evolution of the magnetic moment. • The effects of the biaxial strain on the band gap and doping levels.

  12. Evaluation of Zinc solubilization potential by different strains of ...

    African Journals Online (AJOL)

    Colony and halo diameters were measured after incubating the plates for 48h in incubator. Zn solubilizing ability of 40 mentioned strains in three replications was studied with ZnO and ZnCO3 solutions in broth assay. The soluble zinc and pH were measured after five days. The results showed, only 8 of 40 strains could form ...

  13. Strain distribution during tensile deformation of nanostructured aluminum samples

    DEFF Research Database (Denmark)

    Kidmose, Jacob; Lu, L.; Winther, Grethe

    2012-01-01

    To optimize the mechanical properties, especially formability, post-process deformation by cold rolling in the range 5–50 % reduction was applied to aluminum sheets produced by accumulative roll bonding to an equivalent strain of 4.8. During tensile testing high resolution maps of the strain...

  14. Optimization of protease production by an actinomycete Strain, PS ...

    African Journals Online (AJOL)

    Actinomycetes were isolated from the sediment samples of an estuarine shrimp pond located along the south east coast of India. During the investigation, a total of 28 strains of actinomycetes were isolated and examined for their protease activity. Among them, one strain PS-18A which was tentatively identified as ...

  15. Strain field due to self-interstitial impurity in Ni

    Indian Academy of Sciences (India)

    Strain field due to self-interstitial impurity in Ni. HITESH SHARMA1 £ and S ... The embedded-atom method have been applied to study the strain field produced by the self-interstitial impurity at the .... where q is a wave vector and the expansion coefficients Q(q)are normal coordinates known in dynamical theory. Since we ...

  16. An embeddable optical strain gauge based on a buckled beam

    Science.gov (United States)

    Du, Yang; Chen, Yizheng; Zhu, Chen; Zhuang, Yiyang; Huang, Jie

    2017-11-01

    We report, for the first time, a low cost, compact, and novel mechanically designed extrinsic Fabry-Perot interferometer (EFPI)-based optical fiber sensor with a strain amplification mechanism for strain measurement. The fundamental design principle includes a buckled beam with a coated gold layer, mounted on two grips. A Fabry-Perot cavity is produced between the buckled beam and the endface of a single mode fiber (SMF). A ceramic ferrule is applied for supporting and orienting the SMF. The principal sensor elements are packaged and protected by two designed metal shells. The midpoint of the buckled beam will experience a deflection vertically when the beam is subjected to a horizontally/axially compressive displacement. It has been found that the vertical deflection of the beam at midpoint can be 6-17 times larger than the horizontal/axial displacement, which forms the basis of a strain amplification mechanism. The user-configurable buckling beam geometry-based strain amplification mechanism enables the strain sensor to achieve a wide range of strain measurement sensitivities. The designed EFPI was used to monitor shrinkage of a square brick of mortar. The strain was measured during the drying/curing stage. We envision that it could be a good strain sensor to be embedded in civil materials/structures under a harsh environment for a prolonged period of time.

  17. Manumycin from a new Streptomyces strain shows antagonistic ...

    African Journals Online (AJOL)

    Manumycin from a new Streptomyces strain shows antagonistic effect against methicillin-resistant Staphylococcus aureus (MRSA)/vancomycin-resistant enterococci (VRE) strains from Korean Hospitals. Yun Hee Choi, Seung Sik Cho, Jaya Ram Simkhada, Chi Nam Seong, Hyo Jeong Lee, Hong Seop Moon, Jin Cheol Yoo ...

  18. Fluorene biodegradation potentials of Bacillus strains isolated from ...

    African Journals Online (AJOL)

    Fluorene biodegradation potentials of Bacillus strains isolated from tropical hydrocarbon-contaminated soils. ... The rate of degradation of fluorene (50 mg/L) by the two isolates, after 30 days of incubation were 0.09 and 0.08 mg/L/h for strains BM1 and BR1, respectively. Gas chromatographic analyses of residual fluorene, ...

  19. Characterization of Bacillus thuringiensis strains from Jordan and ...

    African Journals Online (AJOL)

    Eight serotypes with Bacillus thuringiensis israelensis being the most common. Out of the twenty-six isolated strains, five strains (serotype: kenyae, kurstaki, kurstaki HD1 and thuringiensis) that produced bipyramid crystal proteins were toxic to the lepidoptera larvae of Ephestia kuehniella Zeller. The SDS-PAGE protein ...

  20. SUSCEPTIBILITY OF BORDETELLA PERTUSSIS STRAINS TO ANTIBACTERIAL PREPARATIONS

    Directory of Open Access Journals (Sweden)

    O. Yu. Borisova

    2013-01-01

    Full Text Available 178 strains of B. pertussis isolated from infected individuals in various regions of Russia from 1948 to 2012 have been studied for their susceptibility to six antibacterial preparations. It has been shown, that B. pertussis strains isolated from 1948 to 1989 were predominantly sensitive to erythromycin. In the following years a gradual decrease in susceptibility of circulating strains of B. pertussis to this antibiotic was registered with the emergence of strains with intermediate susceptibility in 22% of cases from 1990 to 2005 (MIC 0,060 mcg/mL, up to 59,3% in the last six years (MIC 0,125 mcg/mL. As for azithromycin, high susceptibility of strains of B. pertussis to this preparation was shown throughout the entire duration of the survey. However, the rate of incidence of intermediate strains reached 14% among those strains isolated from 1990 to 2005, and is now at 32%. Thus, after several decades of active use of antibiotics pertussis underwent a series of transformations resulting in a decrease in susceptibility of B. pertussis strains to erythromycin and azithromycin.

  1. The shape of a strain-based failure assessment diagram

    Energy Technology Data Exchange (ETDEWEB)

    Budden, P.J., E-mail: peter.budden@edf-energy.com [EDF Energy, Barnett Way, Barnwood, Gloucester GL4 3RS (United Kingdom); Ainsworth, R.A. [EDF Energy, Barnett Way, Barnwood, Gloucester GL4 3RS (United Kingdom)

    2012-01-15

    There have been a number of recent developments of strain-based fracture assessment approaches, including proposals by Budden [Engng Frac Mech 2006;73:537-52] for a strain-based failure assessment diagram (FAD) related to the conventional stress-based FAD. However, recent comparisons with finite element (FE) data have shown that this proposed strain-based FAD can be non-conservative in some cases, particularly for deeper cracks and materials with little strain-hardening capacity. Therefore, this paper re-examines the shape of the strain-based FAD, guided by these FE analyses and some theoretical analysis. On this basis, modified proposals for the shape of the strain-based FAD are given, including simplified and more detailed options in line with the options available for stress-based FADs in existing fitness-for-service procedures. The proposals are then illustrated by a worked example and by comparison with FE data, which demonstrate that the new proposals are generally conservative. - Highlights: Black-Right-Pointing-Pointer The strain-based failure assessment diagram approach to fracture is developed. Black-Right-Pointing-Pointer The new approach modifies earlier proposals by Budden. Black-Right-Pointing-Pointer A new generic Option 1 strain-based failure assessment diagram is proposed. Black-Right-Pointing-Pointer Validation based on finite element J data for plates and cylinders is presented. Black-Right-Pointing-Pointer The new approach is generally conservative compared with the finite element data.

  2. 38 CFR 4.58 - Arthritis due to strain.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Arthritis due to strain... FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.58 Arthritis due to strain. With service incurred lower extremity amputation or shortening, a disabling arthritis, developing in...

  3. Validation of binary typing for Staphylococcus aureus strains

    NARCIS (Netherlands)

    N. van Leeuwen; M. Heck; A.F. van Belkum (Alex); H.A. Verbrugh (Henri); W.B. van Leeuwen (Willem); J. van der Velden (Jos)

    1999-01-01

    textabstractMost of the DNA-based methods for genetic typing of Staphylococcus aureus strains generate complex banding patterns. Therefore, we have developed a binary typing procedure involving strain-differentiating DNA probes which were generated on the basis of

  4. Antimicrobial susceptibility pattern of Vibrio cholerae 01 strains ...

    African Journals Online (AJOL)

    Results: A total of 181 V. cholerae 01 strains were studied during two epidemic periods when tetracycline or erythromycin was used for treatment of patients with severe disease. Among the 94 V. cholerae Ol strains isolated in 1997; 98.6%, 93.6%, 83%, 81.9%, 36.2%, 35.5%, 3.2% were sensitive to ciprofloxacin, tetracycline, ...

  5. Passive wireless strain monitoring of tire using capacitance change

    Science.gov (United States)

    Matsuzaki, Ryosuke; Todoroki, Akira

    2004-07-01

    In-service strain monitoring of tires of automobile is quite effective for improving the reliability of tires and Anti-lock Braking System (ABS). Since conventional strain gages have high stiffness and require lead wires, the conventional strain gages are cumbersome for the strain measurements of the tires. In a previous study, the authors proposed a new wireless strain monitoring method that adopts the tire itself as a sensor, with an oscillating circuit. This method is very simple and useful, but it requires a battery to activate the oscillating circuit. In the present study, the previous method for wireless tire monitoring is improved to produce a passive wireless sensor. A specimen made from a commercially available tire is connected to a tuning circuit comprising an inductance and a capacitance as a condenser. The capacitance change of tire causes change of the tuning frequency. This change of the tuned radio wave enables us to measure the applied strain of the specimen wirelessly, without any power supply from outside. This new passive wireless method is applied to a specimen and the static applied strain is measured. As a result, the method is experimentally shown to be effective as a passive wireless strain monitoring of tires.

  6. An electrical strain gage for the tensile testing of paper

    Science.gov (United States)

    Douglas M. Jewett

    1963-01-01

    A direct-reading strain gage has been developed at the U.S. Forest Products Laboratory that provides rapid and accurate measurement of the stress - strain properties of paper. The gage, which employs a differential transformer, is particularly suited to servo-operated x-y recorders.

  7. Autochthonous fungal strains with high ligninolytic activities from ...

    African Journals Online (AJOL)

    These positive strains were further screened in liquid culture and laccase, and lignin and Mn2+-oxidizing peroxidases activities were assayed. Of the 67 strains grown on liquid medium, 28 produced at least one of these 3 enzymes. The 8 highest producers of ligninolytic activities were identified by molecular techniques and ...

  8. Effect of specialized combined strains on reconstituted milk reduced ...

    African Journals Online (AJOL)

    Volatiles of these cheeses were determined by solid phase microextraction-gas chromatography-mass spectrometry and texture by the textural profile analysis. The EPS-producing strain could hold moisture and result in cheese with higher yield compared to the non EPS-producing strain. Meanwhile, the cheese made with ...

  9. Inoculation effects of two South African cyanobacteria strains on ...

    African Journals Online (AJOL)

    Two South African cyanobacteria strains (coded 3g and 7e) of the genus Nostoc were evaluated for improvement of the aggregate stability of a silty loam soil with low organic C content and compared with Nostoc strain 9v isolated from a Tanzanian soil. The soil was either cropped with maize or non-cropped and inoculated ...

  10. Changes occurring in plain, straining and winter yoghurt during the ...

    African Journals Online (AJOL)

    Changes occurring in plain, straining and winter yoghurt during the storage periods. S Köse, E Ocak. Abstract. In this study, winter yoghurt, straining yoghurt and yoghurt samples produced from homogenized and non-homogenized sheep and a mixture of sheep and cows milks were evaluated during the storage periods.

  11. Homology of plasmids in strains of unicellular cyanobacteria

    NARCIS (Netherlands)

    Hondel, C.A.M.J.J. van den; Keegstra, W.; Borrias, W.E.; Arkel, G.A. van

    Six strains of unicellular cyanobacteria were examined for the presence of plasmids. Analysis of lysates of these strains by CsCl-ethidium bromide density centrifugation yielded a major chromosomal DNA band and a minor band containing covalently closed circular plasmid DNA, as shown by electron

  12. Identification of pH tolerant Bradyrhizobium japonicum strains and ...

    African Journals Online (AJOL)

    Owner

    Eight strains of Bradyrhizobium japonicum were isolated from the root nodules of soybean cultivar PK. 472 collected from Adaptive Trial Centre, Bundi, India. All the isolates were authenticated through plant assay test in germination pouches. Growth of the isolated strains on different pH levels was observed and three ...

  13. Draft Genome Sequence of Mycobacterium chimaera Type Strain Fl-0169

    Science.gov (United States)

    We report the draft genome sequence of the type strain Mycobacterium chimaera Fl-0169T, a member of the Mycobacterium avium complex (MAC). M. chimaera Fl-0169T was isolated from a patient in Italy and is highly similar to strains of M. chimaera isolated in Ireland, though Fl-016...

  14. Aflatoxin B 1 producing potential of Aspergillus flavus strains ...

    African Journals Online (AJOL)

    Aflatoxin B 1 (AFB1) producing potential of different strains of Aspergillus flavus, isolated from 1,200 stored rice grains collected from 43 locations in 20 rice growing states in India was investigated. Eighty-five strains of A. flavus were isolated from the discolored rice grains and tested for their AFB1 producing potential on ...

  15. On the role of dislocations in heavily strained materials

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Kanert, O.; Arsenault, RJ; Cole, D; Gross, T; Sizek, H; Liaw, P; Parameswaran, S; Kostorz, G

    1996-01-01

    As a tribute to professor Hans Weertman upon the occasion of his 70th birthday this paper deals with the role of dislocations in materials deformed at very high strain rates. In contrast to classical crystal deformation experiments which occur typically at strain rates of 10(-5) s(-1) to 10(-1)

  16. Formation of biofilm by strains of Listeria monocytogenes isolated ...

    African Journals Online (AJOL)

    Quantification of biofilm formation by 40 Listeria monocytogenes strains from wara soft cheese and its processing environment was assessed on glass vials surfaces. Attachement to glass surface was quantified using a crystal violet binding assay. All the 40 strains produced biofilms after 48 and 72 h incubation at 37oC.

  17. Obturator internus strain in the hip of an adolescent athlete.

    Science.gov (United States)

    Busfield, Benjamin T; Romero, Denise M

    2009-11-01

    A male 13-year-old presented with acute onset of right hip pain as he prepared to kick a soccer ball. A case of acute strain of the obturator internus is reported. The strain resolved completely after a period of activity modification and physical therapy.

  18. ANSYS Simulation of Residual Strains in Butt-welded Joints

    Directory of Open Access Journals (Sweden)

    A. Atroshenko

    2014-07-01

    Full Text Available The effect of thermal-strain cycle on residual strains in thin-walled circular seams of cylindrical shells using TIG butt welds was studied. Estimates were calculated using numerical modelling. The structure was made of corrosion-resistant austenitic steels.

  19. Effect of biosurfactant from two strains of Pseudomonas on ...

    African Journals Online (AJOL)

    Two Pseudomonas strains isolated from oil-contaminated soil which produce biosurfactant were studied. The biosurfactant containing broth formed stable emulsions with liquid light paraffin, cooking medium vegetable oil and toluene. The strains under study produce extra cellular biosurfactant in the culture media.

  20. Genotyping and evaluation of Pleurotus ostreatus (oyster mushroom) strains

    NARCIS (Netherlands)

    Sonnenberg, A.S.M.; Hendrickx, P.M.; Sumiati, E.

    2005-01-01

    Oyster mushrooms (Pleurotus ostreatus) represent one of the most popular mushroom species grown in Indonesia. There is a need for strains that are better adapted to the climate conditions at Java, where most mushrooms in Indonesia are produced. Strains that can produce mushrooms at 22 to 28 oC and

  1. Cardiac biplane strain imaging: initial in vivo experience.

    NARCIS (Netherlands)

    Lopata, R.G.P.; Nillesen, M.M.; Verrijp, C.N.; Singh, S.K.; Lammens, M.M.Y.; Laak, J.A.W.M. van der; Wetten, H.B. van; Thijssen, J.M.; Kapusta, L.; Korte, C.L. de

    2010-01-01

    In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to

  2. Potential application of Saccharomyces cerevisiae strains for the ...

    African Journals Online (AJOL)

    The UFMG-A1240 strain showed the lowest ethanol yield and therefore not suitable for the production of distilled spirits made of bananas, despite being useful for the production of cachaça. Methanol contents did not significantly vary among the five strains tested, except for UFMG-A1007, which produced significantly higher ...

  3. Strain characterization of FinFETs using Raman spectroscopy

    NARCIS (Netherlands)

    Kaleli, B.; van Hemert, T.; Hueting, Raymond Josephus Engelbart; Wolters, Robertus A.M.

    2013-01-01

    Metal induced strain in the channel region of silicon (Si) fin-field effect transistor (FinFET) devices has been characterized using Raman spectroscopy. The strain originates from the difference in thermal expansion coefficient of Si and titanium-nitride. The Raman map of the device region is used

  4. Cervical vertebral strain measurements under axial and eccentric loading.

    Science.gov (United States)

    Pintar, F A; Yoganandan, N; Pesigan, M; Reinartz, J; Sances, A; Cusick, J F

    1995-11-01

    The mid to lower cervical spine is a common site for compression related injury. In the present study, we determined the patterns of localized strain distribution in the anterior aspect of the vertebral body and in the lateral masses of lower cervical three-segment units. Miniature strain gages were mounted to human cadaveric vertebrae. Each preparation was line-loaded using a knife-edge oriented in the coronal plane that was moved incrementally from anterior to posterior to induce compression-flexion or compression-extension loading. Uniform compressive loading and failure runs were also conducted. Failure tests indicated strain shifting to "restabilize" the preparation after failure of a component. Under these various compressive loading vectors, the location which resulted in the least amount of deformation for a given force application (i.e., stiffest axis) was quantified to be in the region between 0.5- 1.0 cm anterior to the posterior longitudinal ligament. The location in which line-loading produced no rotation (i.e., balance point) was in this region; it was also close to where the vertebral body strains change from compressive to tensile. Strain values from line loading in this region produced similar strains as recorded under uniform compressive loading, and this was also the region of minimum strain. The region of minimum strain was also more pronounced under higher magnitudes of loading, suggesting that as the maximum load carrying capacity is reached the stiffest axis becomes more well defined.

  5. Development of bioluminescent Salmonella strains for use in food safety

    Directory of Open Access Journals (Sweden)

    Bailey R Hartford

    2008-01-01

    Full Text Available Abstract Background Salmonella can reside in healthy animals without the manifestation of any adverse effects on the carrier. If raw products of animal origin are not handled properly during processing or cooked to a proper temperature during preparation, salmonellosis can occur. In this research, we developed bioluminescent Salmonella strains that can be used for real-time monitoring of the pathogen's growth on food products. To accomplish this, twelve Salmonella strains from the broiler production continuum were transformed with the broad host range plasmid pAKlux1, and a chicken skin attachment model was developed. Results Salmonella strains carrying pAKlux1 constitutively expressed the luxCDABE operon and were therefore detectable using bioluminescence. Strains were characterized in terms of bioluminescence properties and plasmid stability. To assess the usefulness of bioluminescent Salmonella strains in food safety studies, we developed an attachment model using chicken skin. The effect of washing on attachment of Salmonella strains to chicken skin was tested using bioluminescent strains, which revealed the attachment properties of each strain. Conclusion This study demonstrated that bioluminescence is a sensitive and effective tool to detect Salmonella on food products in real-time. Bioluminescence imaging is a promising technology that can be utilized to evaluate new food safety measures for reducing Salmonella contamination on food products.

  6. Antimicrobial resistance of non-clinical Escherichia coli strains from ...

    African Journals Online (AJOL)

    This study was carried out to determine resistance profiles of Escherichia coli strains isolated from clinically healthy chickens in Nsukka, southeast Nigeria. A total of 324 E. coli strains isolated from cloaca swabs from 390 chickens were tested against 16 antimicrobial agents using the disc diffusion method. The antibiotics ...

  7. Interplay between real and pseudomagnetic field in graphene with strain

    NARCIS (Netherlands)

    Kim, K.J.; Blanter, Y.M.; Ahn, K.H.

    2011-01-01

    We investigate electric and magnetic properties of graphene with rotationally symmetric strain. The strain generates a large pseudomagnetic field with alternating sign in space, which forms a strongly confined quantum dot connected to six chiral channels. The orbital magnetism, degeneracy, and

  8. Draft Genome Sequence of Alicyclobacillus acidoterrestris Strain ATCC 49025

    OpenAIRE

    Shemesh, Moshe; Pasvolsky, Ronit; Sela, Noa; Green, Stefan J.; Zakin, Varda

    2013-01-01

    Alicyclobacillus acidoterrestris is a spore-forming Gram-positive, thermo-acidophilic, nonpathogenic bacterium which contaminates commercial pasteurized fruit juices. The draft genome sequence for A.?acidoterrestris strain ATCC 49025 is reported here, providing genetic data relevant to the successful adaptation and survival of this strain in its ecological niche.

  9. Investigation of stress–strain models for confined high strength ...

    Indian Academy of Sciences (India)

    The ascending branch of stress–strain curves depended on the ratio of confinement reinforcement was similar to the modified Kent–Park model and the descending branch similar to the Nagashima model. Keywords. High strength concrete; confined concrete; stress–strain models; ductility toughness. 1. Introduction.

  10. Stress, strain, ignorance and reinventing the wheel: Understanding ...

    African Journals Online (AJOL)

    Stress, strain, ignorance and reinventing the wheel: Understanding central venous pressure. ... Because of this characteristic stress and strain relationship, the central venous pressure cannot be a simple and static indication of the volume inside the container and ... Keywords: asthma; child; anaesthesia; bronchospasm ...

  11. Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors.

    Science.gov (United States)

    Jiang, Ying; Liu, Zhiyuan; Matsuhisa, Naoji; Qi, Dianpeng; Leow, Wan Ru; Yang, Hui; Yu, Jiancan; Chen, Geng; Liu, Yaqing; Wan, Changjin; Liu, Zhuangjian; Chen, Xiaodong

    2018-01-30

    Stretchable strain sensors play a pivotal role in wearable devices, soft robotics, and Internet-of-Things, yet these viable applications, which require subtle strain detection under various strain, are often limited by low sensitivity. This inadequate sensitivity stems from the Poisson effect in conventional strain sensors, where stretched elastomer substrates expand in the longitudinal direction but compress transversely. In stretchable strain sensors, expansion separates the active materials and contributes to the sensitivity, while Poisson compression squeezes active materials together, and thus intrinsically limits the sensitivity. Alternatively, auxetic mechanical metamaterials undergo 2D expansion in both directions, due to their negative structural Poisson's ratio. Herein, it is demonstrated that such auxetic metamaterials can be incorporated into stretchable strain sensors to significantly enhance the sensitivity. Compared to conventional sensors, the sensitivity is greatly elevated with a 24-fold improvement. This sensitivity enhancement is due to the synergistic effect of reduced structural Poisson's ratio and strain concentration. Furthermore, microcracks are elongated as an underlying mechanism, verified by both experiments and numerical simulations. This strategy of employing auxetic metamaterials can be further applied to other stretchable strain sensors with different constituent materials. Moreover, it paves the way for utilizing mechanical metamaterials into a broader library of stretchable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Strain-induced properties of epitaxial VOx thin films

    NARCIS (Netherlands)

    Rata, AD; Hibma, T

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

  13. the capacity of megasphaera elsdenii strain ncimb 41125 to control ...

    African Journals Online (AJOL)

    David

    these strains have not been commercialised because of one or more reasons which include inadequate growth rate, inability to .... Similarly, the yeast, Saccharomyces cerevisiae, stimulated the growth of .... Table 1 Vessel pH and lactic acid concentration (mM) at 3, 6 and 12 h post-inoculation of Control and strain. 41125 on ...

  14. Drug gastrointestinal absorption in rat: Strain and gender differences.

    Science.gov (United States)

    Oltra-Noguera, Davinia; Mangas-Sanjuan, Victor; González-Álvarez, Isabel; Colon-Useche, Sarin; González-Álvarez, Marta; Bermejo, Marival

    2015-10-12

    Predictive animal models of intestinal drug absorption are essential tools in drug development to identify compounds with promising biopharmaceutical properties. In situ perfusion absorption studies are routinely used in the preclinical setting to screen drug candidates. The objective of this work is to explore the differences in magnitude and variability on intestinal absorption associated with rat strain and gender. Metoprolol and Verapamil absorption rate coefficients were determined using the in situ closed loop perfusion model in four strains of rats and in both genders. Strains used were Sprague-Dawley, Wistar-Han, Wistar-Unilever, Long-Evans and CD∗IGS. In the case of Metoprolol only CD∗IGS and Wistar Unilever showed differences between males and females. For Verapamil, Wistar Han and Sprague-Dawley strains do not show differences between male and female rats. That means that in these strains permeability data from male and female could be combined. In male rats, which are commonly used for permeability estimation, there were differences for Metoprolol permeability between Sprague-Dawley (with lower permeability values) and the other strains, while for Verapamil Sprague-Dawley and Wistar-Han showed the lower permeability values. In conclusion, the selection of rat's strain and gender for intestinal absorption experiments is a relevant element during study design and data from different strains may not be always comparable. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. DNA-based identification of Lentinula edodes strains with species ...

    African Journals Online (AJOL)

    The primer-pair LE1F/R was specific in amplifications of ATCC-defined L. edodes strains and did not amplify DNA from six medicinally and nutritionally important fungal reference strains, Oyster (Pleurotus ostreatus), Maitake (Grifola frondosa), Enoki (Flammulina velutipes), Baby bella (Agaricus bisporus), Porcini (Boletus ...

  16. Antimicrobial Resistance of Staphylococcal Strains Isolated from Various Pathological Products

    Directory of Open Access Journals (Sweden)

    Laura-Mihaela SIMON

    2010-12-01

    Full Text Available Background: The optimal choice of antimicrobial therapy is an important problem in hospital environment in which the selection of resistant and virulent strains easy occurs. S. aureus and especially MRSA(methicillin-resistant S. aureus creates difficulties in both treatment and prevention of nosocomial infections. Aim: The purpose of this study is to determine the sensitivity and the resistance to chemotherapy of staphylococci strains isolated from various pathological products. Material and Method: We identified Staphylococccus species after morphological appearance, culture properties, the production of coagulase, hemolisines and the enzyme activity. The susceptibility tests were performed on Mueller-Hinton medium according to CLSI (Clinical and Laboratory Standards Institute. Results: The strains were: MSSA (methicillin-susceptible S. aureus (74%, MRSA (8%, MLS B (macrolides, lincosamides and type B streptogramines resistance (12% and MRSA and MLS B (6%. MRSA strains were more frequently isolated from sputum. MRSA associated with the MLS B strains were more frequently isolated from pus. MLS B strains were more frequently isolated from sputum and throat secretions. All S. aureus strains were susceptible to vancomycin and teicoplanin. Conclusions: All staphylococcal infections require resistance testing before treatment. MLS B shows a high prevalence among strains of S. aureus. The association between MLS B and MRSA remains a major problem in Romania.

  17. Selection of inoculum size and Saccharomyces cerevisiae strain for ...

    African Journals Online (AJOL)

    SAM

    2014-07-02

    Jul 2, 2014 ... The aim of this work was to select an inoculum concentration and a Saccharomyces cerevisiae strain for ethanol production in the simultaneous saccharification and fermentation (SSF) of sugar cane bagasse. Three concentrations of inoculum (0.4, 4.0 and 8.0 g/L) and two strains of S. cerevisiae. (UFPEDA ...

  18. Rat islet isolation yield and function are donor strain dependent

    NARCIS (Netherlands)

    de Groot, M; de Haan, BJ; Schuurs, TA; van Schilfgaarde, R; Leuvenink, HGD; KEIZER, J

    Effective rat islet isolation is pertinent for successful islet transplantation and islet studies in vitro. To determine which rat strain yields the highest number of pure and functional islets, four commonly used rat strains were compared with regard to islet yield, islet purity and islet function.

  19. Degradation of 4-fluorophenol by Arthrobacter sp strain IF1

    NARCIS (Netherlands)

    Ferreira, Maria Isabel M.; Marchesi, Julian R.; Janssen, Dick B.

    A Gram-positive bacterial strain capable of aerobic biodegradation of 4-fluorophenol (4-FP) as the sole source of carbon and energy was isolated by selective enrichment from soil samples collected near an industrial site. The organism, designated strain IF1, was identified as a member of the genus

  20. Isolation of polyvinyl chloride degrading bacterial strains from ...

    African Journals Online (AJOL)

    In the present investigation, potent microbial strains degrading plastic constituting polymer polyvinyl chloride (PVC) were isolated using enrichment culture technique. To increase the chances of isolating such strain which could have adapted to metabolize plastic constituting polymers, samples were collected from different ...

  1. From Measurements Errors to a New Strain Gauge Design

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard; Zike, Sanita; Salviato, Marco

    2015-01-01

    Significant over-prediction of the material stiffness in the order of 1-10% for polymer based composites has been experimentally observed and numerical determined when using strain gauges for strain measurements instead of non-contact methods such as digital image correlation or less stiff methods...

  2. Job strain and the risk of depression: is reporting biased?

    DEFF Research Database (Denmark)

    Kolstad, Henrik; Hansen, Åse Marie; Kærgaard, Anette

    2011-01-01

    It is unknown whether the relation between job strain and depression reflects causal characteristics of the working environment or reporting bias. The authors investigated reporting bias by analyzing individual versus work-unit measures of job strain and the risk of depressive symptoms (n = 287) ...

  3. Effect of Selected Azotobacter Bacterial Strains on the Enrichment of ...

    African Journals Online (AJOL)

    Effect of Selected Azotobacter Bacterial Strains on the Enrichment of Cassava Waste during Sold State Fermentation. ... The effect of three different strains of Azotobacter bacteria in solid substrate fermentation on cassava waste was evaluated. The substrate was incubated at 300c for 10 days inoculation with the ...

  4. Fusion of two yeast strains for enhanced crude oil degradation ...

    African Journals Online (AJOL)

    A hybrid strain S24 was developed from Saccharomyces cerevisiae Y5A and Saccharomyces carlsbergensis Y7B, using protoplast fusion technique. The yeast protoplasts were prepared using gut juice from Helix pomatia (Land Snail) as cell digesting enzyme. The ability of the wild and the hybrid strains to degrade medium ...

  5. Selection of inoculum size and Saccharomyces cerevisiae strain for ...

    African Journals Online (AJOL)

    Selection of inoculum size and Saccharomyces cerevisiae strain for ethanol production in simultaneous saccharification and fermentation (SSF) of sugar cane ... (0.4, 4.0 and 8.0 g/L) and two strains of S. cerevisiae (UFPEDA 1238 and UFPEDA 1334) were used to ferment a culture medium containing glucose as the carbon ...

  6. Genomic and gene variation in Mycoplasma hominis strains

    DEFF Research Database (Denmark)

    Christiansen, Gunna; Andersen, H; Birkelund, Svend

    1987-01-01

    DNAs from 14 strains of Mycoplasma hominis isolated from various habitats, including strain PG21, were analyzed for genomic heterogeneity. DNA-DNA filter hybridization values were from 51 to 91%. Restriction endonuclease digestion patterns, analyzed by agarose gel electrophoresis, revealed...

  7. Isolation and characterization of lipase-producing Bacillus strains ...

    African Journals Online (AJOL)

    Bacillus strains (B1 - B5) producing extra cellular lipase were isolated from the soil sample of coconut oil industry. The strains were identified by morphological and biochemical characters. Growth of the organisms and lipase production were measured with varying pH (4 - 9) temperature (27, 37 and 47ºC) and various ...

  8. Aflatoxin B1 producing potential of Aspergillus flavus strains isolated ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-07-20

    Jul 20, 2009 ... Extraction of AFB1 from A. flavus strains grown on agar media. Eighty five strains of A. flavus isolated from rice grain samples were grown on sterilized different agar media (AFPA, Czapeks agar, PDA and YES agar) for 5 days at 25 ± 2°C. Three replications were maintained for each isolate for each media.

  9. Full-length genomic analysis of korean porcine sapelovirus strains

    DEFF Research Database (Denmark)

    Son, Kyu-Yeol; Kim, Deok-Song; Kwon, Joseph

    2014-01-01

    the structural features of PSV genomes, the full-length nucleotide sequences of three Korean PSV strains were determined and analyzed using bioinformatic techniques in comparison with other known PSV strains. The Korean PSV genomes ranged from 7,542 to 7,566 nucleotides excluding the 3' poly(A) tail, and showed...

  10. Discrimination of citrus tristeza virus (CTV) strains using Mexican ...

    African Journals Online (AJOL)

    Administrator

    2007-02-19

    Feb 19, 2007 ... zone of Cameroon) on Lisbon lemon tree. The SNCL2 viral strain provokes severe stem-pitting symptoms, whereas the SNCL4 strain provokes moderate symptoms. Plants inoculation. Inoculation was carried out on three years old healthy plants, by double grafting of the shield of Mexican lime on citrange ...

  11. Selective Medium for Mosquito-Pathogenic Strains of Bacillus sphaericus

    OpenAIRE

    Yousten, Allan A.; Fretz, Susan B.; Jelley, Scott A.

    1985-01-01

    A selective medium (BATS), which contains arginine as the sole carbon and nitrogen source and which also contains streptomycin, allowed growth of 18 mosquito-pathogenic strains of Bacillus sphaericus. It inhibited the growth of 68% of the nonpathogenic B. sphaericus strains tested as well as other Bacillus spp. and aquatic bacteria.

  12. Selective Medium for Mosquito-Pathogenic Strains of Bacillus sphaericus

    Science.gov (United States)

    Yousten, Allan A.; Fretz, Susan B.; Jelley, Scott A.

    1985-01-01

    A selective medium (BATS), which contains arginine as the sole carbon and nitrogen source and which also contains streptomycin, allowed growth of 18 mosquito-pathogenic strains of Bacillus sphaericus. It inhibited the growth of 68% of the nonpathogenic B. sphaericus strains tested as well as other Bacillus spp. and aquatic bacteria. PMID:16346821

  13. Autochthonous fungal strains with high ligninolytic activities from ...

    African Journals Online (AJOL)

    This work represents the first report on the ability of autochthonous fungi of Tunisia to produce ligninolytic enzymes. Three hundred fifteen fungal strains were isolated from different Tunisian biotopes. These fungal strains were first screened for lignin-modifying enzymes on solid media containing Poly R-478 or ABTS.

  14. Antibiotics susceptibility pattern of Escherichia coli strains isolated ...

    African Journals Online (AJOL)

    This study was carried out to determine the susceptibility of E coli strains isolated from broiler and layer chicken with colisepticemia to antibiotics used in poultry industry in the country. A total of fifty seven E. coli strains isolated from 43 broiler and14 layer farms with colisepticemia in Khartoum and Gezera state were ...

  15. Job strain in relation to body mass index

    DEFF Research Database (Denmark)

    Nyberg, S T; Heikkilä, K; Fransson, E I

    2012-01-01

    Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses.......Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses....

  16. Strain measurement on a compact nuclear reactor steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Scaldaferri, Denis Henrique Bianchi; Gomes, Paulo de Tarso Vida; Mansur, Tanius Rodrigues, E-mail: dhbs@cdtn.b, E-mail: gomespt@cdtn.b, E-mail: tanius@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Pozzo, Renato del, E-mail: delpozzo@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil); Mola, Jairo [Unitecnica Engenharia, Sao Paulo, SP (Brazil)

    2011-07-01

    This work presents the strain measurement procedures applied to a compact nuclear reactor steam generator, during a hydrostatic test, using strain gage technology. The test was divided in two steps: primary side test and secondary side test. In the primary side test twelve points for strain measurement using rectangular rosettes, three points (two external and one internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. In the secondary side test 18 points for strain measurement using rectangular rosettes, four points (two external and two internal) for temperature measurement using special strain gages and one point for pressure measurement using a pressure transducer were monitored. The measurement points on both internal and external pressurizer walls were established from pre-calculated stress distribution by means of numerical approach (finite elements modeling). Strain values using a quarter Wheatstone bridge circuit were obtained. Stress values, from experimental strain were determined, and to numerical calculation results were compared. (author)

  17. Effect of Strain on the Reactivity of Metal Surfaces

    DEFF Research Database (Denmark)

    Mavrikakis, Manos; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Self-consistent density functional calculations for the adsorption of O and CO, and the dissociation of CO on strained and unstrained Ru(0001) surfaces are used to show how strained metal surfaces have chemical properties that are significantly different from those of unstrained surfaces. Surface...

  18. Gender, General Strain Theory, Negative Emotions, and Disordered Eating

    Science.gov (United States)

    Piquero, Nicole Leeper; Fox, Kristan; Piquero, Alex R.; Capowich, George; Mazerolle, Paul

    2010-01-01

    Much of the prior work on General Strain Theory (GST) has focused on how strain and negative emotions interrelate to produce criminal--especially violent--activity. Very little research has extended GST to examine other types of non-criminal, negative behavior, such as self-harming behaviors associated with disordered eating, a traditionally…

  19. Job strain as a risk factor for coronary heart disease

    DEFF Research Database (Denmark)

    Kivimäki, Mika; Nyberg, Solja T; Batty, G David

    2012-01-01

    Published work assessing psychosocial stress (job strain) as a risk factor for coronary heart disease is inconsistent and subject to publication bias and reverse causation bias. We analysed the relation between job strain and coronary heart disease with a meta-analysis of published and unpublished...

  20. Strain-related acid production by oral streptococci

    DEFF Research Database (Denmark)

    de Soet, JJ; Nyvad, Bente; Kilian, Mogens

    2000-01-01

    that of the other oral streptococci, including S. mitis, S. oralis, S. gordonii, S. sanguis, S. intermedius, S. anginosus, S. constellatus, and S. vestibularis. However, the V(ap) of some strains of S. mitis biovar 1 and S. oralis, particularly at pH values of 7.0 and 6.0, exceeded that of some strains of S. mutans...