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Sample records for macro-residual strains due

  1. Lattice Strain Due to an Atomic Vacancy

    PubMed Central

    Li, Shidong; Sellers, Michael S.; Basaran, Cemal; Schultz, Andrew J.; Kofke, David A.

    2009-01-01

    Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations. PMID:19582230

  2. 38 CFR 4.58 - Arthritis due to strain.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 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...

  3. 38 CFR 4.58 - Arthritis due to strain.

    Code of Federal Regulations, 2010 CFR

    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...

  4. 38 CFR 4.58 - Arthritis due to strain.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 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...

  5. 38 CFR 4.58 - Arthritis due to strain.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 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...

  6. 38 CFR 4.58 - Arthritis due to strain.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 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...

  7. Are quantum dots in unexpected locations due to strain?

    NASA Astrophysics Data System (ADS)

    Zimmerman, Neil; Thorbeck, Ted

    It is a fairly common occurrence that, in top-gated Si quantum dots, the dots appear in reproducible but unexpected positions. For instance, sometimes a group will make gates in order to electrostatically generate tunnel barriers, but discover that the quantum dot is formed underneath the gate rather than between two barrier gates. We will discuss the possibility that such quantum dots arise from the mechanical strain induced by the gate. The model is simple: i) We simulate metal or polysilicon gates on top of a Si/SiO2 wafer, and calculate the stress and strain from differential thermal contraction of the materials; ii) Using the fact that the energy of the Si conduction band depends on strain through the deformation potential, we then convert the strain modulation to a potential energy modulation. As an example, we find that, for a single Al gate, there is a potential well directly underneath the gate with the size of a few meV, in agreement with recent experimental results. We also show that polysilicon gates will not produce such strain-induced quantum dots.

  8. Meltwater production due to strain heating in Storglaciären, Sweden

    NASA Astrophysics Data System (ADS)

    Aschwanden, Andy; Blatter, Heinz

    2005-12-01

    Storglaciären, northern Sweden, is temperate in most parts except for a cold surface layer in the ablation zone. One of four possible sources for liquid water in temperate ice is melting due to strain heating. Velocity fields are calculated with an ice flow model, so that calculated and observed surface velocities agree. Meltwater accumulation is computed by integrating strain heating along trajectories starting at the surface in the accumulation area and ending at the cold-temperate transition surface in the ablation zone. The distribution of moisture content due to strain heating alone is mapped in a longitudinal section of Storglaciären. Values reach more than 10 g of water per kilogram ice-water mixture in the lowest parts of the temperate domain. For this moisture content the rate factor is more than 3 times higher than for water-free ice, and therefore water production by strain heating is important for the modeling of temperate and polythermal glaciers.

  9. Atomistic mechanisms of strain relaxation due to ductile void growth in ultrathin films of face-centered-cubic metals

    NASA Astrophysics Data System (ADS)

    Gungor, M. Rauf; Maroudas, Dimitrios

    2005-06-01

    A comprehensive computational analysis is reported of the atomistic mechanisms of strain relaxation and failure in free-standing Cu thin films under applied biaxial tensile strain for strain levels up to 6%. The analysis focuses on nanometer-scale-thick films with a preexisting void extending across the film thickness and the film plane oriented normal to the [111] crystallographic direction. Our computational study is based on isothermal-isostrain large-scale molecular-dynamics simulations within an embedded-atom-method parametrization for Cu. Our analysis has revealed various regimes in the film's mechanical response as the applied strain level increases. Within the considered strain range, after an elastic response at a low strain (<2%), void growth is the major strain relaxation mechanism mediated by the emission of perfect screw dislocation pairs from the void surface and subsequent dislocation propagation; as a result, a plastic zone forms around the void. Plastic deformation is accompanied by the glide motion of the dislocations emitted from the void surface, void surface morphological transitions, formation of a step pattern on the film's surfaces, dislocation jogging, vacancy generation due to gliding jogged dislocations, dislocation-vacancy interactions, vacancy pipe diffusion along dislocation cores, as well as dislocation-dislocation interactions. The increase in film surface roughness with increasing strain eventually leads to nucleation and propagation from the film surfaces of threading dislocation loops, which ultimately break up when they reach the opposite free surface of the thin film.

  10. Group A Escherichia coli-Related Purpura Fulminans: an Unusual Manifestation Due to an Unusual Strain?

    PubMed Central

    Amara, Marlène; Bonacorsi, Stéphane; Bedel, Jérôme; Mira, Jean-Paul; Laurent, Virginie; Socha, Koryna; Bruneel, Fabrice; Pangon, Béatrice; Bédos, Jean-Pierre

    2014-01-01

    We describe an exceptional case of life-threatening group A Escherichia coli-induced purpura fulminans. Genotyping of common polymorphisms in genes involved in innate immunity or coagulation did not reveal known susceptibility to such a manifestation. Genetic analysis of the strain revealed an unusual conserved virulence plasmidic region, pointing out its potential virulence. PMID:25232165

  11. Topological end states due to inhomogeneous strains in wrinkled semiconducting ribbons

    NASA Astrophysics Data System (ADS)

    Pandey, Sudhakar; Ortix, Carmine

    2016-05-01

    We show that curvature-induced inhomogeneous strain distributions in nanoscale buckled semiconducting ribbons lead to the existence of end states which are topologically protected by inversion symmetry. These end-state doublets, corresponding to the so-called Maue-Shockley states, are robust against weak disorder. By identifying and calculating the corresponding topological invariants, we further show that a buckled semiconducting ribbon undergoes topological phase transitions between trivial and nontrivial insulating phases by varying its real-space geometry.

  12. Highly localized strain fields due to planar defects in epitaxial SrBi2Nb2O9 thin films

    NASA Astrophysics Data System (ADS)

    Boulle, A.; Guinebretière, R.; Dauger, A.

    2005-04-01

    Thin films of (00l) oriented SrBi2Nb2O9 epitaxially grown on SrTiO3 by sol-gel spin coating have been studied by means of high-resolution x-ray diffraction reciprocal space mapping. It is shown that these materials contain highly localized heterogeneous strain fields due to imperfect stacking faults (i.e., faults that do not propagate throughout the crystallites building up the film). In the film plane, the strain fields are confined to 11 nm wide regions and characterized by a vertical displacement of 0.18c (where c is the cell parameter) showing that the stacking faults are mainly composed of one additional (or missing) perovskite layer. Prolonged thermal annealing at 700 °C strongly reduces the density of stacking faults and yields a more uniform strain distribution within the film volume without inducing significant grain growth.

  13. Stored energy in metallic glasses due to strains within the elastic limit

    NASA Astrophysics Data System (ADS)

    Greer, A. L.; Sun, Y. H.

    2016-06-01

    Room temperature loading of metallic glasses, at stresses below the macroscopic yield stress, raises their enthalpy and causes creep. Thermal cycling of metallic glasses between room temperature and 77 K also raises their enthalpy. In both cases, the enthalpy increases are comparable to those induced by heavy plastic deformation, but, as we show, the origins must be quite different. For plastic deformation, the enthalpy increase is a fraction (<10%) of the work done (WD) (and, in this sense, the behaviour is similar to that of conventional polycrystalline metals and alloys). In contrast, the room temperature creep and the thermal cycling involve small strains well within the elastic limit; in these cases, the enthalpy increase in the glass exceeds the WD, by as much as three orders of magnitude. We argue that the increased enthalpy can arise only from an endothermic disordering process drawing heat from the surroundings. We examine the mechanisms of this process. The increased enthalpy ('stored energy') is a measure of rejuvenation and appears as an exothermic heat of relaxation on heating the glass. The profile of this heat release (the 'relaxation spectrum') is analysed for several metallic glasses subjected to various treatments. Thus, the effects of the small-strain processing (creep and thermal cycling) can be better understood, and we can explore the potential for improving properties, in particular the plasticity, of metallic glasses. Metallic glasses can exhibit a wide range of enthalpy at a given temperature, and small-strain processing may assist in accessing this for practical purposes.

  14. Single 1 g dose of cefotaxime in the treatment of infections due to penicillinase-producing strains of Neisseria gonorrhoeae.

    PubMed Central

    de Koning, G A; Tio, D; van den Hoek, J A; van Klingeren, B

    1983-01-01

    One hundred and two patients with an uncomplicated infection due to penicillinase-producing strains of Neisseria gonorrhoeae (PPNG) were treated with a single 1 g dose of cefotaxime. At follow-up within 15 days all genital and rectal infections were cured. Pharyngeal infections also seemed to respond to this treatment. A relatively high proportion (30.9%) of patients, however, developed post-gonococcal urethritis. PMID:6299449

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

    PubMed Central

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

    2015-01-01

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

  16. Impact comminution of solids due to local kinetic energy of high shear strain rate: I. Continuum theory and turbulence analogy

    NASA Astrophysics Data System (ADS)

    Bažant, Zdeněk P.; Caner, Ferhun C.

    2014-03-01

    The modeling of high velocity impact into brittle or quasibrittle solids is hampered by the unavailability of a constitutive model capturing the effects of material comminution into very fine particles. The present objective is to develop such a model, usable in finite element programs. The comminution at very high strain rates can dissipate a large portion of the kinetic energy of an impacting missile. The spatial derivative of the energy dissipated by comminution gives a force resisting the penetration, which is superposed on the nodal forces obtained from the static constitutive model in a finite element program. The present theory is inspired partly by Grady's model for expansive comminution due to explosion inside a hollow sphere, and partly by analogy with turbulence. In high velocity turbulent flow, the energy dissipation rate gets enhanced by the formation of micro-vortices (eddies) which dissipate energy by viscous shear stress. Similarly, here it is assumed that the energy dissipation at fast deformation of a confined solid gets enhanced by the release of kinetic energy of the motion associated with a high-rate shear strain of forming particles. For simplicity, the shape of these particles in the plane of maximum shear rate is considered to be regular hexagons. The particle sizes are assumed to be distributed according to the Schuhmann power law. The condition that the rate of release of the local kinetic energy must be equal to the interface fracture energy yields a relation between the particle size, the shear strain rate, the fracture energy and the mass density. As one experimental justification, the present theory agrees with Grady's empirical observation that, in impact events, the average particle size is proportional to the (-2/3) power of the shear strain rate. The main characteristic of the comminution process is a dimensionless number Ba (Eq. (37)) representing the ratio of the local kinetic energy of shear strain rate to the maximum possible

  17. TESTING AND ANALYSIS OF CAP CONCRETE STRESS AND STRAIN DUE TO SHRINKAGE, CREEP, AND EXPANSION FINAL REPORT

    SciTech Connect

    Guerrero, H.; Restivo, M.

    2011-08-01

    In-situ decommissioning of Reactors P- and R- at the Savannah River Site will require filling the reactor vessels with a special concrete based on materials such as magnesium phosphate, calcium aluminate or silica fume. Then the reactor vessels will be overlain with an 8 ft. thick layer of Ordinary Portland Cement (OPC) steel reinforced concrete, called the 'Cap Concrete'. The integrity of this protective layer must be assured to last for a sufficiently long period of time to avoid ingress of water into the reactor vessel and possible movement of radioactive contamination into the environment. During drying of this Cap Concrete however, shrinkage strains are set up in the concrete as a result of diffusion and evaporation of water from the top surface. This shrinkage varies with depth in the poured slab due to a non-uniform moisture distribution. This differential shrinkage results in restraint of the upper layers with larger shrinkage by lower layers with lesser displacements. Tensile stresses can develop at the surface from the strain gradients in the bulk slab, which can lead to surface cracking. Further, a mechanism called creep occurs during the curing period or early age produces strains under the action of restraining forces. To investigate the potential for surface cracking, an experimental and analytical program was started under TTQAP SRNL-RP-2009-01184. Slab sections made of Cap Concrete mixture were instrumented with embedded strain gages and relative humidity sensors and tested under controlled environmental conditions of 23 C and relative humidities (RH) of 40% and 80% over a period of 50 days. Calculation methods were also developed for predictions of stress development in the full-scale concrete placement over the reactor vessels. These methods were evaluated by simulating conditions for the test specimens and the calculation results compared to the experimental data. A closely similar test with strain gages was performed by Kim and Lee for a

  18. [Epidural abscess due to a Mycobacterium tuberculosis strain with primary resistance to isoniazid and ethambutol].

    PubMed

    Sener, Alper; Akçalı, Alper; Karatağ, Ozan; Koşar, Sule; Değirmenci, Yıldız; Akman, Tarık

    2012-10-01

    Tuberculosis is primarily characterized by pulmonary involvement, however, one third of the cases exhibit extrapulmonary tuberculosis. In this report, a case of epidural abscess due to Mycobacterium tuberculosis with primary resistance to isoniazid and ethambutol was presented. A 57-year-old male patient was admitted to emergency service with ten days history of weakness in legs, disability of walking and fever. Neurological examination revealed paraplegia of lower extremities, numbness distal to T2 disc level and hyperactivity of deep tendon reflexes indicating transverse myelitis. Laboratory findings were as follows; ESR: 74 mm/hour, CRP: 22 g/L, ALT: 42 IU/L, AST: 45 IU/L and white blood cell count 23.000/mm3 (45% polymorphonuclear leukocyte, 45% lymphocyte, 10% monocyte). Spinal magnetic resonance imaging showed a fusiform abscess localized at anterior epidural space and extending along levels of C5-6 and C6-7. The longitudinal dimension of the abscess was 3 cm. The lesion was hypointense on T1 and hyperintense on T2 weighted MRI images with prominent rim shaped contrast enhancement on contrast-enhanced T1-weighted images. At fourth day of hospitalization the patient underwent neurosurgical management. M.tuberculosis was isolated from the cultures of operation material by Mycobacteria Growth Incubator Tube system (MGIT, BBL; BD, USA) on the 12th day. The isolate was found susceptible to streptomycin and rifampisin, but resistant to isoniazid and ethambutol. The treatment was initiated with rifampicin 600 mg/day, pyrazinamid 2 g/day, ethambutol 1.5 g/day and levofloxacin 500 mg/day. At the end of second month levofloxacin 500 mg/day and rifampisin 600 mg/day combination was sustained and total treatment period was planned as nine months. As far as the national literature was considered, this was the first case of extrapulmonary tuberculosis with primary resistance to isoniazid and ethambutol. PMID:23188583

  19. Temperature increase of Zircaloy-4 cladding tubes due to plastic heat dissipation during tensile tests at 0.1-10 s-1 strain rates

    NASA Astrophysics Data System (ADS)

    Hellouin de Menibus, Arthur; Auzoux, Quentin; Besson, Jacques; Crépin, Jérôme

    2014-11-01

    This study is focused on the impact of rapid Reactivity Initiated Accident (RIA) representative strain rates (about 1 s-1 NEA, 2010) on the behavior and fracture of unirradiated cold work stress relieved Zircaloy-4 cladding tubes. Uniaxial ring tests (HT) and plane strain ring tensile tests (PST) were performed in the 0.1-10 s-1 strain rate range, at 25 °C. The local temperature increase due to plastic dissipation was measured with a high-speed infrared camera. Limited temperature increases were measured at 0.1 s-1 strain rate. Limited but not strongly localized temperature increases were measured at 1 s-1. Large temperature increase were measured at 5 and 10 s-1 (142 °C at 5 s-1 strain rate in HT tests). The local temperature increase induced heterogeneous temperature fields, which enhanced strain localization and resulted in a reduction of the plastic elongation at fracture.

  20. Impact Fragmentation and Crushing of Concrete and Other Solids Due to Kinetic Energy of High Shear Strain Rate

    NASA Astrophysics Data System (ADS)

    Bazant, Zdenek; Kirane, Kedar

    While numerous studies have dealt with dynamic crack propagation, they have not led to a macroscopic continuum model usable in FE analysis. Recent work on such a model is reviewed. The key idea is that comminution under high-rate shear is driven by the release local kinetic (rather than strain) energy of the shear strain rate field in forming finite-size fragments. At strain rates >103/s, this energy exceeds the maximum possible elastic strain energy by orders of magnitude. It is found that the particle size scales as the -2/3 power of the shear strain rate and as the 2/3 power of interface fracture energy, and the released and dissipated kinetic energy as the 2/3 power of the shear strain rate. These results explain the long debated phenomenon of ``dynamic overstress''. In FE simulations, this kinetic energy of strain rate field can be dissipated either by equivalent viscosity or by the work of increased strength limits. In simulating the impact of missiles into concrete walls, both approaches give nearly equivalent results. A dimensionless indicator of the comminution intensity is also formulated. The theory was inspired by noting that the local kinetic energy of shear strain rate plays a role analogous to the local kinetic energy of eddies in turbulent flow.

  1. Molecular epidemiology of recurrent clinical mastitis due to Streptococcus uberis: evidence of both an environmental source and recurring infection with the same strain.

    PubMed

    Abureema, Salem; Smooker, Peter; Malmo, Jakob; Deighton, Margaret

    2014-01-01

    This study was undertaken because clinicians and farmers have observed that a considerable number of cows diagnosed with Streptococcus uberis mastitis have recurrences of mastitis in the same or a different quarter. The study was an attempt to answer whether these recurring cases were due to treatment failure (in which case a search would have begun for a better treatment for Strep. uberis mastitis) or due to reinfection with a different strain of Strep. uberis. Using pulsed-field gel electrophoresis (PFGE), we determined that the majority of recurrences (20 of 27) were caused by a new strain of Strep. uberis, indicating that treatment of the initial infection had been successful. A small number of recurrences (5 of 27) were caused by the initial strain, indicating persistence. The remaining 2 recurrences occurred in a new quarter but with the initial strain of Strep. uberis, indicating either spread between quarters or reactivation of a previous subclinical infection. Analysis of the PFGE profiles failed to reveal any strain-specific propensity to persist, because strains causing recurrences occurred in most of the major clusters. PMID:24239086

  2. Change of the V I curve and critical current with applied tensile strain due to cracking of filaments in Bi2223 composite tape

    NASA Astrophysics Data System (ADS)

    Shin, J. K.; Ochiai, S.; Okuda, H.; Sugano, M.; Oh, S. S.

    2008-11-01

    The critical current at 77 K of multifilamentary Bi2223 composite tape was studied under applied tensile strain experimentally and analytically. Beyond the irreversible strain, the critical currents (IC) decreased significantly with increasing applied tensile strain (ɛc), due to the enhanced cracking of the Bi2223 filaments. The voltage generation in the voltage-current relation was calculated by the current share model in which the transport current is shared by the Bi2223 filament and Ag near the cracked portion. Then the critical current was estimated with a 1 µV cm-1 criterion. By the application of the current share model to the experimental result, the effective crack length responsible for the reduction in critical current was estimated, with which the change of critical current could be described satisfactorily as a function of applied strain.

  3. Sequential Outbreaks Due to a New Strain of Neisseria Meningitidis Serogroup C in Northern Nigeria, 2013-14

    PubMed Central

    Funk, Anna; Uadiale, Kennedy; Kamau, Charity; Caugant, Dominique A.; Ango, Umar; Greig, Jane

    2014-01-01

    Background Neisseria meningitidis serogroup C (NmC) outbreaks occur infrequently in the African meningitis belt; the most recent report of an outbreak of this serogroup was in Burkina Faso, 1979. Médecins sans Frontières (MSF) has been responding to outbreaks of meningitis in northwest Nigeria since 2007 with no reported cases of serogroup C from 2007-2012. MenAfrivac®, a serogroup A conjugate vaccine, was first used for mass vaccination in northwest Nigeria in late 2012. Reactive vaccination using polysaccharide ACYW135 vaccine was done by MSF in parts of the region in 2008 and 2009; no other vaccination campaigns are known to have occurred in the area during this period. We describe the general characteristics of an outbreak due to a novel strain of NmC in Sokoto State, Nigeria, in 2013, and a smaller outbreak in 2014 in the adjacent state, Kebbi. Methods Information on cases and deaths was collected using a standard line-list during each week of each meningitis outbreak in 2013 and 2014 in northwest Nigeria. Initial serogroup confirmation was by rapid Pastorex agglutination tests. Cerebrospinal fluid (CSF) samples from suspected meningitis patients were sent to the WHO Reference Laboratory in Oslo, where bacterial isolates, serogrouping, antimicrobial sensitivity testing, genotype characterisation and real-time PCR analysis were performed. Results In the most highly affected outbreak areas, all of the 856 and 333 clinically suspected meningitis cases were treated in 2013 and 2014, respectively. Overall attack (AR) and case fatality (CFR) rates were 673/100,000 population and 6.8% in 2013, and 165/100,000 and 10.5% in 2014. Both outbreaks affected small geographical areas of less than 150km2 and populations of less than 210,000, and occurred in neighbouring regions in two adjacent states in the successive years. Initial rapid testing identified NmC as the causative agent. Of the 21 and 17 CSF samples analysed in Oslo, NmC alone was confirmed in 11 and 10

  4. Strain evolution in Si substrate due to implantation of MeV ion observed by extremely asymmetric x-ray diffraction

    SciTech Connect

    Emoto, T.; Ghatak, J.; Satyam, P. V.; Akimoto, K.

    2009-08-15

    We studied the strain introduced in a Si(111) substrate due to MeV ion implantation using extremely asymmetric x-ray diffraction and measured the rocking curves of asymmetrical 113 diffraction for the Si substrates implanted with a 1.5 MeV Au{sup 2+} ion at fluence values of 1x10{sup 13}, 5x10{sup 13}, and 1x10{sup 14}/cm{sup 2}. The measured curves consisted of a bulk peak and accompanying subpeak with an interference fringe. The positional relationship of the bulk peak to the subpeak and the intensity variation of those peaks with respect to the wavelengths of the x rays indicated that crystal lattices near the surface were strained; the lattice spacing of surface normal (111) planes near the surface was larger than that of the bulk. Detailed strain profiles along the depth direction were successfully estimated using a curve-fitting method based on Darwin's dynamical diffraction theory. Comparing the shapes of resultant strain profiles, we found that a strain evolution rapidly occurred within a depth of approx300 nm at fluence values between 1x10{sup 13} and 5x10{sup 13}/cm{sup 2}. This indicates that formation of the complex defects progressed near the surface when the fluence value went beyond a critical value between 1x10{sup 13} and 5x10{sup 13}/cm{sup 2} and the defects brought a large strain to the substrate.

  5. A nosocomial outbreak due to Enterobacter cloacae strains with the E. hormaechei genotype in patients treated with fluoroquinolones.

    PubMed Central

    Davin-Regli, A; Bosi, C; Charrel, R; Ageron, E; Papazian, L; Grimont, P A; Cremieux, A; Bollet, C

    1997-01-01

    During a 7-month period, we isolated 21 highly fluoroquinolone-resistant Enterobacter cloaecae strains in units from two hospitals in Marseille, France. Random amplification of polymorphic DNA showed clonal identity between isolates which, furthermore, presented the Enterobacter hormaechei genotype on DNA-DNA hybridization. The emergence of this clone was observed only in patients treated with fluoroquinolones. PMID:9157119

  6. Finite element modelling predicts changes in joint shape and cell behaviour due to loss of muscle strain in jaw development

    PubMed Central

    Brunt, Lucy H.; Norton, Joanna L.; Bright, Jen A.; Rayfield, Emily J.; Hammond, Chrissy L.

    2015-01-01

    Abnormal joint morphogenesis is linked to clinical conditions such as Developmental Dysplasia of the Hip (DDH) and to osteoarthritis (OA). Muscle activity is known to be important during the developmental process of joint morphogenesis. However, less is known about how this mechanical stimulus affects the behaviour of joint cells to generate altered morphology. Using zebrafish, in which we can image all joint musculoskeletal tissues at high resolution, we show that removal of muscle activity through anaesthetisation or genetic manipulation causes a change to the shape of the joint between the Meckel's cartilage and Palatoquadrate (the jaw joint), such that the joint develops asymmetrically leading to an overlap of the cartilage elements on the medial side which inhibits normal joint function. We identify the time during which muscle activity is critical to produce a normal joint. Using Finite Element Analysis (FEA), to model the strains exerted by muscle on the skeletal elements, we identify that minimum principal strains are located at the medial region of the joint and interzone during mouth opening. Then, by studying the cells immediately proximal to the joint, we demonstrate that biomechanical strain regulates cell orientation within the developing joint, such that when muscle-induced strain is removed, cells on the medial side of the joint notably change their orientation. Together, these data show that biomechanical forces are required to establish symmetry in the joint during development. PMID:26253758

  7. True polar wander of a quasi-fluid planet with a fossil shape: Effect of strain energy due to tidal deformation

    NASA Astrophysics Data System (ADS)

    Harada, Y.

    2011-12-01

    In the present study, temporal variation of a paleo-pole position due to TPW is formulated and calculated based on strain energy in a previous study. Especially, quasi-fluid approximation is suitable to deal with large-scale and long-term variation of a paleo-pole position. Thus, an orientation of a paleo-rotation axis in each time step is estimated in here by following conventional formulation with the quasi-fluid approximation for TPW, and simultaneously by taking total energy minimization into account. In practice, this procedure is physically same as to incorporate elastic torque due to tidal deformation of a lithosphere into the Liouville equation including the quasi-fluid approximation. In this study, like the previous one, only one symmetric surface load is regarded as a driving force of TPW for convenience sake. In this calculation, variable parameters are defined as follows: a location of emplacement, duration of formation, and maximum of intensity of a load. The result with strain energy is compared with that without strain energy. As a result, the case with the strain energy indicates different characteristics from that without the strain energy in the following points. First, the paleo-poles under steady states are different each other in the cases for same parameters. These results are not consistent even with the previous results concerning just the final condition. Second, also in the cases for same parameters, time scales when the paleo-poles reach the static limits are different. These results demonstrate the fact that strain energy within a lithosphere effectively weakens influence of a load on TPW. Although this kind of influence has already been pointed out by the previous results just in the cases of the steady states, the present results further revealed similar effect also on a characteristic time scale of TPW. Strictly speaking, however, it is impossible to estimate this exact time scale only by reducing an effective size of a load. This is

  8. Use of multiple molecular subtyping techniques to investigate a Legionnaires' disease outbreak due to identical strains at two tourist lodges.

    PubMed Central

    Mamolen, M; Breiman, R F; Barbaree, J M; Gunn, R A; Stone, K M; Spika, J S; Dennis, D T; Mao, S H; Vogt, R L

    1993-01-01

    A multistate outbreak of Legionnaires' disease occurred among nine tour groups of senior citizens returning from stays at one of two lodges in a Vermont resort in October 1987. Interviews and serologic studies of 383 (85%) of the tour members revealed 17 individuals (attack rate, 4.4%) with radiologically documented pneumonia and laboratory evidence of legionellosis. A survey of tour groups staying at four nearby lodges and of Vermont-area medical facilities revealed no additional cases. Environmental investigation of common tour stops revealed no likely aerosol source of Legionella infection outside the lodges. Legionella pneumophila serogroup 1 was isolated from water sources at both implicated lodges, and the monoclonal antibody subtype matched those of the isolates from six patients from whom clinical isolates were obtained. The cultures reacted with monoclonal antibodies MAB1, MAB2, 33G2, and 144C2 to yield a 1,2,5,7 or a Benidorm 030E pattern. The strains were also identical by alloenzyme electrophoresis and DNA ribotyping techniques. The epidemiologic and laboratory data suggest that concurrent outbreaks occurred following exposures to the same L. pneumophila serogroup 1 strain at two separate lodges. Multiple molecular subtyping techniques can provide essential information for epidemiologic investigations of Legionnaires' disease. PMID:8253953

  9. Diarrhea, bacteremia and multiorgan dysfunction due to an extraintestinal pathogenic Escherichia coli strain with enteropathogenic E. coli genes

    PubMed Central

    Kessler, Robert; Nisa, Shahista; Hazen, Tracy H.; Horneman, Amy; Amoroso, Anthony; Rasko, David A.; Donnenberg, Michael S.

    2015-01-01

    A 55-year-old man with well-controlled HIV had severe diarrhea for 3 weeks and developed multiorgan dysfunction and bacteremia due to Escherichia coli. The genome of the patient's isolate had features characteristic of extraintestinal pathogenic E. coli and genes distantly related to those defining enteropathogenic E. coli. PMID:26410828

  10. Computer Simulation of Stress-Strain State of Pipeline Section Affected by Abrasion Due to Mechanical Impurities

    NASA Astrophysics Data System (ADS)

    Burkov, P. V.; Afanas’ev, R. G.; Burkova, S. P.

    2016-04-01

    The paper presents the effect of abrasive wear of the pipeline section occurred due to mechanical impurities in the transported gas flow. The approaches to the detection of the maximum specific wear of the pipeline wall and the geometry of abrasion are the main problems of computer simulation described in this paper.

  11. Diarrhea, bacteremia and multiorgan dysfunction due to an extraintestinal pathogenic Escherichia coli strain with enteropathogenic E. coli genes.

    PubMed

    Kessler, Robert; Nisa, Shahista; Hazen, Tracy H; Horneman, Amy; Amoroso, Anthony; Rasko, David A; Donnenberg, Michael S

    2015-11-01

    A 55-year-old man with well-controlled HIV had severe diarrhea for 3 weeks and developed multiorgan dysfunction and bacteremia due to Escherichia coli. The genome of the patient's isolate had features characteristic of extraintestinal pathogenic E. coli and genes distantly related to those defining enteropathogenic E. coli. PMID:26410828

  12. Necrotizing pneumonia due to clonally diverse Staphylococcus aureus strains producing Panton-Valentine leukocidin: the Czech experience.

    PubMed

    Rájová, J; Pantůček, R; Petráš, P; Varbanovová, I; Mašlaňová, I; Beneš, J

    2016-02-01

    A prospective study (2007-2013) was undertaken to investigate clinical features and prognostic factors of necrotizing pneumonia caused by Staphylococcus aureus producing Panton-Valentine leukocidin (PVL) in the Czech Republic. Twelve cases of necrotizing pneumonia were detected in 12 patients (median age 25 years) without severe underlying disease. Eight cases occurred in December and January and the accumulation of cases in the winter months preceding the influenza season was statistically significant (P < 0·001). The course of pneumonia was very rapid, leading to early sepsis and/or septic shock in all but one patient. Seven patients died and mortality was fourfold higher in those patients presenting with primary pneumonia than with pneumonia complicating other staphylococcal/pyogenic infection elsewhere in the body. The S. aureus isolates displayed considerable genetic variability and were assigned to five lineages CC8 (n = 3), CC15 (n = 2), CC30 (n = 2), CC80 (n = 1), and CC121 (n = 3) and one was a singleton of ST154 (n = 1), all were reported to be associated with community-acquired infection. Four strains were methicillin resistant. The high case-fatality rate can only be reduced by improving the speed of diagnosis and a rapid test to detect S. aureus in the airways is needed. PMID:26201459

  13. Hospital Acquired Pneumonia Due to Achromobacter spp. in a Geriatric Ward in China: Clinical Characteristic, Genome Variability, Biofilm Production, Antibiotic Resistance and Integron in Isolated Strains

    PubMed Central

    Liu, Chao; Pan, Fei; Guo, Jun; Yan, Weifeng; Jin, Yi; Liu, Changting; Qin, Long; Fang, Xiangqun

    2016-01-01

    Background: Hospital-acquired pneumonia (HAP) due to Achromobacter has become a substantial concern in recent years. However, HAP due to Achromobacter in the elderly is rare. Methods: A retrospective analysis was performed on 15 elderly patients with HAP due to Achromobacter spp., in which the sequence types (STs), integrons, biofilm production and antibiotic resistance of the Achromobacter spp. were examined. Results: The mean age of the 15 elderly patients was 88.8 ± 5.4 years. All patients had at least three underlying diseases and catheters. Clinical outcomes improved in 10 of the 15 patients after antibiotic and/or mechanical ventilation treatment, but three patients had chronic infections lasting more than 1 year. The mortality rate was 33.3% (5/15). All strains were resistant to aminoglycosides, aztreonam, nitrofurantoin, and third- and fourth-generation cephalosporins (except ceftazidime and cefoperazone). Six new STs were detected. The most frequent ST was ST306. ST5 was identified in two separate buildings of the hospital. ST313 showed higher MIC in cephalosporins, quinolones and carbapenems, which should be more closely considered in clinical practice. All strains produced biofilm and had integron I and blaOXA-114-like. The main type was blaOXA-114q. The variable region of integron I was different among strains, and the resistance gene of the aminoglycosides was most commonly inserted in integron I. Additionally, blaPSE-1 was first reported in this isolate. Conclusion: Achromobacter spp. infection often occurs in severely ill elders with underlying diseases. The variable region of integrons differs, suggesting that Achromobacter spp. is a reservoir of various resistance genes. PMID:27242678

  14. Material property discontinuities in intervertebral disc porohyperelastic finite element models generate numerical instabilities due to volumetric strain variations.

    PubMed

    Ruiz, C; Noailly, J; Lacroix, D

    2013-10-01

    Numerical studies of the intervertebral disc (IVD) are important to better understand the load transfer and the mechanobiological processes within the disc. Among the relevant calculations, fluid-related outputs are critical to describe and explore accurately the tissue properties. Porohyperelastic finite element models of IVD can describe accurately the disc behaviour at the organ level and allow the inclusion of fluid effects. However, results may be affected by numerical instabilities when fast load rates are applied. We hypothesized that such instabilities would appear preferentially at material discontinuities such as the annulus-nucleus boundary and should be considered when testing mesh convergence. A L4-L5 IVD model including the nucleus, annulus and cartilage endplates were tested under pure rotational loads, with different levels of mesh refinement. The effect of load relaxation and swelling were also studied. Simulations indicated that fluid velocity oscillations appeared due to numerical instability of the pore pressure spatial derivative at material discontinuities. Applying local refinement only was not enough to eliminate these oscillations. In fact, mesh refinements had to be local, material-dependent, and supplemented by the creation of a material transition zone, including interpolated material properties. Results also indicated that oscillations vanished along load relaxation, and faster attenuation occurred with the incorporation of the osmotic pressure. We concluded that material discontinuities are a major cause of instability for poromechanical calculations in multi-tissue models when load velocities are simulated. A strategy was presented to address these instabilities and recommendations on the use of IVD porohyperelastic models were given. PMID:23796430

  15. Nosocomial Outbreak Due to a Multiresistant Strain of Pseudomonas aeruginosa P12: Efficacy of Cefepime-Amikacin Therapy and Analysis of β-Lactam Resistance

    PubMed Central

    Dubois, Véronique; Arpin, Corinne; Melon, Monique; Melon, Bernard; Andre, Catherine; Frigo, Cécile; Quentin, Claudine

    2001-01-01

    Over a 3-year period, 67 patients of the Hospital of Pau (Pau, France), including 64 patients hospitalized in the adult intensive care unit (ICU), were colonized and/or infected by strains of Pseudomonas aeruginosa P12, resistant to all potentially active antibiotics except colistin. Most patients were mechanically ventilated and presented respiratory tract infections. Since cefepime and amikacin were the least inactive antibiotics by MIC determination, all ICU patients were treated with this combination, and most of them benefited. Cefepime-amikacin was found highly synergistic in vitro. Ribotyping and arbitrary primer-PCR analysis confirmed the presence of a single clonal isolate. Isoelectrofocusing revealed that the epidemic strain produced large amounts of the chromosomal cephalosporinase and an additional enzyme with a pI of 5.7, corresponding to PSE-1, as demonstrated by PCR and sequencing. Outer membrane protein profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the absence of a ca. 46-kDa protein, likely to be OprD, and increased production of two ca. 49- and 50-kDa proteins, consistent with the outer membrane components of the efflux systems, MexAB-OprM and MexEF-OprN. Thus, we report here a nosocomial outbreak due to multiresistant P. aeruginosa P12 exhibiting at least four mechanisms of β-lactam resistance, i.e., production of the penicillinase PSE-1, overproduction of the chromosomal cephalosporinase, loss of OprD, and overexpression of efflux systems, associated with a better activity of cefepime than ceftazidime. PMID:11376037

  16. New aspects about reduced LCF-life time of spherical ductile cast iron due to dynamic strain aging at intermediate temperatures

    NASA Astrophysics Data System (ADS)

    Mouri, Hayato; Wunderlich, Wilfried; Hayashi, Morihito

    2009-06-01

    Spherical ductile cast iron (FCD400) is widely used as container material in nuclear energy processing line due to its superior mechanical properties and low price. Fatigue properties in low cycle fatigue (LCF) can be described well by the Manson-Coffin-Basquin's rule. However, at intermediate temperature range between 453 and 723 K the elongation-temperature-diagram shows a significantly 20-10% reduced elongation and an increase in yield stress in tensile test experiments. These non-linear deviations and the phenomenon of less ductility at intermediate temperatures are known for a long time [1] [K. Chijiiwa, M. Hayashi, Mechanical properties of ductile cast iron at temperature in the region of room temperature to liquid, Imono 51 (7) (2004) 395-400]. But the following explanation is presented for the first time. In the same temperature range as the reduced fatigue life time dynamic strain ageing (DSA) also known as Portevin-le-Chartelier effect with the formation of visible serrations occurs. Both phenomena are explained by interaction effects between carbon diffusion and dislocation velocity which have at this temperature the same order of magnitude. However, this phenomenon shows interesting behavior at intermediate temperature range. During the low cycle fatigue test, DSA phenomenon disappeared, but mechanical properties show clear evidence of DSA phenomenon. Therefore, the purpose of this paper is to study the correlation of DSA occurrence, LCF and mechanical properties.

  17. Increased prevalence of carbapenem resistant Enterobacteriaceae in hospital setting due to cross-species transmission of the bla NDM-1 element and clonal spread of progenitor resistant strains.

    PubMed

    Wang, Xuan; Chen, Gongxiang; Wu, Xiaoyan; Wang, Liangping; Cai, Jiachang; Chan, Edward W; Chen, Sheng; Zhang, Rong

    2015-01-01

    This study investigated the transmission characteristics of carbapenem-resistant Enterobacteriaceae (CRE) strains collected from a hospital setting in China, in which consistent emergence of CRE strains were observable during the period of May 2013 to February 2014. Among the 45 CRE isolates tested, 21 (47%) strains were found to harbor the bla NDM-1 element, and the rest of 24 CRE strains were all positive for bla KPC-2. The 21 bla NDM-1-borne strains were found to comprise multiple Enterobacteriaceae species including nine Enterobacter cloacae, three Escherichia coli, three Citrobacter freundii, two Klebsiella pneumoniae, two Klebsiella oxytoca, and two Morganella morganii strains, indicating that cross-species transmission of bla NDM-1 is a common event. Genetic analyses by PFGE and MLST showed that, with the exception of E. coli and E. cloacae, strains belonging to the same species were often genetically unrelated. In addition to bla NDM-1, several CRE strains were also found to harbor the bla KPC-2, bla VIM-1, and bla IMP-4 elements. Conjugations experiments confirmed that the majority of carbapenem resistance determinants were transferable. Taken together, our findings suggest that transmission of mobile resistance elements among members of Enterobacteriaceae and clonal spread of CRE strains may contribute synergistically to a rapid increase in the population of CRE in clinical settings, prompting a need to implement more rigorous infection control measures to arrest such vicious transmission cycle in CRE-prevalent areas. PMID:26136735

  18. Rapid spread of Neisseria gonorrhoeae ciprofloxacin resistance due to a newly introduced resistant strain in Nuuk, Greenland, 2012–2015: a community-based prospective cohort study

    PubMed Central

    Pedersen, Michael Lynge; Poulsen, Peter; Berthelsen, Lene; Nørgaard, Christina; Hoffmann, Steen; Jensen, Jørgen Skov

    2016-01-01

    Objectives To determine the antimicrobial susceptibility and genotype distribution of Neisseria gonorrhoeae strains isolated from a cohort of patients in Nuuk, Greenland in order to assess the risk of rapid spread in the event of introduction of new strains. Methods Gonococcal isolates (n=102) obtained from a prospective cohort study of ciprofloxacin resistance were collected between March 2012 and February 2013. Etest minimal inhibitory concentrations (MICs) were determined for ciprofloxacin, azithromycin, ceftriaxone, penicillin, tetracycline, spectinomycin and gentamicin. All isolates were subjected to molecular typing using N. gonorrhoeae multiantigen sequence typing (NG-MAST). After the introduction of a ciprofloxacin-resistant strain in early 2014, an additional 18 isolates were characterised. Results During the study period, all 102 isolates were fully susceptible to ciprofloxacin (≤0.03 mg/L), azithromycin, spectinomycin, gentamicin and ceftriaxone. 10 different NG-MAST types circulated in Nuuk but 7 were found as single isolates, and 3 of the 7 belonged to 1 of the 3 major genogroups (G210, G9816 and G9817) together comprising 96% of the 102 isolates. ST210 accounted for 55% of the 102 strains. The newly introduced ciprofloxacin resistant strain belonged to ST2400 and dominated the population with 59% resistant strains within 6 months after its introduction. All G2400 strains had MICs≥2 mg/L. Conclusions Introduction of a ciprofloxacin-resistant strain into a very homogeneous N. gonorrhoeae population led to an explosive spread of the resistant clone, probably as a result of large sexual networks suggested by the strain homogeneity. Careful surveillance of antimicrobial susceptibility is essential to avoid widespread treatment failure in closed populations. PMID:27577587

  19. An attenuated Salmonella enterica serovar Typhimurium strain reduces disease severity, fecal shedding, and gastrointestinal colonization in swine due to virulent S. Typhimurium challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Salmonella serovars frequently colonize swine without causing overt disease. Pathogen interventions are needed to limit Salmonella colonization in swine. Vaccination with an attenuated Salmonella strain may reduce pathogen carriage in swine and enhance food safety. Methods: Swine study ...

  20. Evaluation of mosquito densoviruses for controlling Aedes aegypti (Diptera: Culicidae): variation in efficiency due to virus strain and geographic origin of mosquitoes.

    PubMed

    Hirunkanokpun, Supanee; Carlson, Jonathan O; Kittayapong, Pattamaporn

    2008-05-01

    Four mosquito densovirus strains were assayed for mortality and infectivity against Aedes aegypti larvae from different geographic regions. The viral titers were quantified by real-time PCR using TaqMan technology. Firstinstar larvae were exposed to the same titer of each densovirus strain for 48 hours. All strains of densoviruses exhibited larvicidal activity and caused more than 80% mortality and infectivity in the three mosquito strains. AalDNV-exposed larvae had the highest mortality rate. The mean time to death of AalDNV-exposed larvae was shorter than other DNVs-exposed larvae. We can conclude that different densovirus strains exhibit some variations in their pathogenicity to different populations of Ae. aegypti mosquitoes. A few mosquitoes from Chachoengsao and Bangkok exposed to AeDNV and AThDNV survived to the adult stage to lay eggs and showed 22% to 50% vertical transmission in the F1 generation. Phylogenetic analysis of four densovirus strains indicated that mosquito densoviruses are separated into two distinct clades. PMID:18458314

  1. Serological response of swine to an attenuated Salmonella enterica serovar Typhimurium strain that reduces gastrointestinal colonization, fecal shedding and disease due to virulent Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine are often asymptomatic carriers of Salmonella spp. Interventions are needed to limit Salmonella colonization of swine to enhance food safety. An attenuated Salmonella enterica serovar Typhimurium mutant strain (BBS 202) was tested in swine to determine whether vaccination could provide protect...

  2. Co-production of 3ADON and 15ADON by cultures of Fusarium graminearum 15ADON strains, but not 3ADON strains, is due to differences in acetyltransferase activity and substrate specificity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium graminearum strains can be assigned to chemotypes, e.g. 3ADON or 15ADON, on the basis of PCR analysis using polymorphisms in the trichothecene biosynthetic genes TRI3 and TRI12. Trichothecene production in liquid culture is consistent with the chemotype predicted with PCR analyses, i.e., ac...

  3. Increased furfural tolerance due to overexpression of NADH-dependent oxidoreductase FucO in Escherichia coli strains engineered for the production of ethanol and lactate.

    PubMed

    Wang, X; Miller, E N; Yomano, L P; Zhang, X; Shanmugam, K T; Ingram, L O

    2011-08-01

    Furfural is an important fermentation inhibitor in hemicellulose sugar syrups derived from woody biomass. The metabolism of furfural by NADPH-dependent oxidoreductases, such as YqhD (low K(m) for NADPH), is proposed to inhibit the growth and fermentation of xylose in Escherichia coli by competing with biosynthesis for NADPH. The discovery that the NADH-dependent propanediol oxidoreductase (FucO) can reduce furfural provided a new approach to improve furfural tolerance. Strains that produced ethanol or lactate efficiently as primary products from xylose were developed. These strains included chromosomal mutations in yqhD expression that permitted the fermentation of xylose broths containing up to 10 mM furfural. Expression of fucO from plasmids was shown to increase furfural tolerance by 50% and to permit the fermentation of 15 mM furfural. Product yields with 15 mM furfural were equivalent to those of control strains without added furfural (85% to 90% of the theoretical maximum). These two defined genetic traits can be readily transferred to enteric biocatalysts designed to produce other products. A similar strategy that minimizes the depletion of NADPH pools by native detoxification enzymes may be generally useful for other inhibitory compounds in lignocellulosic sugar streams and with other organisms. PMID:21685167

  4. Neisseria gonorrhoeae strain with high-level resistance to spectinomycin due to a novel resistance mechanism (mutated ribosomal protein S5) verified in Norway.

    PubMed

    Unemo, Magnus; Golparian, Daniel; Skogen, Vegard; Olsen, Anne Olaug; Moi, Harald; Syversen, Gaute; Hjelmevoll, Stig Ove

    2013-02-01

    Gonorrhea may become untreatable, and new treatment options are essential. Verified resistance to spectinomycin is exceedingly rare. However, we describe a high-level spectinomycin-resistant (MIC, >1,024 μg/ml) Neisseria gonorrhoeae strain from Norway with a novel resistance mechanism. The resistance determinant was a deletion of codon 27 (valine) and a K28E alteration in the ribosomal protein 5S. The traditional spectinomycin resistance gene (16S rRNA) was wild type. Despite this exceedingly rare finding, spectinomycin available for treatment of ceftriaxone-resistant urogenital gonorrhea would be very valuable. PMID:23183436

  5. Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn(4+)-Rich Antiphase Boundaries.

    PubMed

    MacLaren, I; Sala, B; Andersson, S M L; Pennycook, T J; Xiong, J; Jia, Q X; Choi, E-M; MacManus-Driscoll, J L

    2015-12-01

    The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions. PMID:26474888

  6. Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn4+-Rich Antiphase Boundaries

    NASA Astrophysics Data System (ADS)

    MacLaren, I.; Sala, B.; Andersson, S. M. L.; Pennycook, T. J.; Xiong, J.; Jia, Q. X.; Choi, E.-M.; MacManus-Driscoll, J. L.

    2015-10-01

    The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn4+-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.

  7. GENERAL ENHANCEMENT OF MUTAGENIC POTENCY OF VARIOUS MUTAGENS DUE TO DELETED GENES IN THE ΔuvrB STRAINS TA 98 AND TA 100 OF SALMONELLA COMPARED WITH STRAINS CONTAINING ONLY A POINT MUTATION IN uvrB

    EPA Science Inventory

    The two most common strains used in Ames mutagenicity assays, TA98 and TA 100, contain a �uvrB mutation designed to enhance the mutagenicity of compounds, presumably due to the loss of the nucleotide excision repair system. We showed previously that the �uvrB mutations in these s...

  8. Long Range Ferromagnetic Order in LaCoO3-δ epitaxial films due to the interplay of epitaxial strain and oxygen vacancy ordering

    DOE PAGESBeta

    Mehta, Virat; Biskup, Nevenko; Arenholz, E; Varela del Arco, Maria; Suzuki, Yuri

    2015-04-23

    We demonstrate that a combination of electronic structure modification and oxygen vacancy ordering can stabilize a long-range ferromagnetic ground state in epitaxial LaCoO3 thin films. Highest saturation magnetization values are found in the thin films in tension on SrTiO3 and (La,Sr)(Al,Ta)O3 substrates and the lowest values are found in thin films in compression on LaAlO3. Electron microscopy reveals oxygen vacancy ordering to varying degrees in all samples, although samples with the highest magnetization are the most defective. Element-specific x-ray absorption techniques reveal the presence of high spin Co2+ and Co3+ as well as low spin Co3+ in different proportions dependingmore » on the strain state. The interactions among the high spin Co ions and the oxygen vacancy superstructure are correlated with the stabilization of the long-range ferromagnetic order.« less

  9. Extensional strain and displacement distribution due to mesoscale normal faults in Late Miocene-Pliocene sedimentary rocks along the northwestern side of the Red Sea, Egypt

    NASA Astrophysics Data System (ADS)

    Zaky, Kh. S.

    2015-09-01

    Field observations are presented on the NW-SE mesoscale, dip-slip, normal faults in the Late Miocene-Pliocene sedimentary rocks, along the northwestern part of the SW side of the Red Sea, Egypt. These faults were initiated parallel to the Red Sea, and were originated by the NE-SW extension associated with the Red Sea opening in the Late Oligocene-Early Miocene time. About 100 mesoscale normal faults were measured in the Late Miocene-Pliocene sedimentary rocks along seven scan-lines. The extensional strain determined in five scan-lines ranges from 2.6393 to 5.12% with an average of 3.53145%. The other two scan-lines have anomalous values of 6.2988 and 15.53%. The represented data demonstrate that the extensional strain varies significantly from profile to profile and even along the fault because of several surficial factors. The first factor is a difference in lithology. The second and third factors are the local stress and the difference between perpendicular to the direction of maximum lateral extension of area and strike of faults. The L-D (Length-Displacement) diagrams along twelve selected faults reveal three patterns. These patterns include a cone-shaped (C-type), meso-shaped (M-type), and a zigzag-shaped (Z-type). The remarkable variation of displacement (D) along the fault plane (L) is a result of the difference in lithology, and/or the overlapping fault segments, as well as the local stress along the faults.

  10. Decrease of U(VI) immobilization capability of the facultative anaerobic strain Paenibacillus sp. JG-TB8 under anoxic conditions due to strongly reduced phosphatase activity.

    PubMed

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2014-01-01

    Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

  11. Decrease of U(VI) Immobilization Capability of the Facultative Anaerobic Strain Paenibacillus sp. JG-TB8 under Anoxic Conditions Due to Strongly Reduced Phosphatase Activity

    PubMed Central

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Selenska-Pobell, Sonja; Merroun, Mohamed L.

    2014-01-01

    Interactions of a facultative anaerobic bacterial isolate named Paenibacillus sp. JG-TB8 with U(VI) were studied under oxic and anoxic conditions in order to assess the influence of the oxygen-dependent cell metabolism on microbial uranium mobilization and immobilization. We demonstrated that aerobically and anaerobically grown cells of Paenibacillus sp. JG-TB8 accumulate uranium from aqueous solutions under acidic conditions (pH 2 to 6), under oxic and anoxic conditions. A combination of spectroscopic and microscopic methods revealed that the speciation of U(VI) associated with the cells of the strain depend on the pH as well as on the aeration conditions. At pH 2 and pH 3, uranium was exclusively bound by organic phosphate groups provided by cellular components, independently on the aeration conditions. At higher pH values, a part (pH 4.5) or the total amount (pH 6) of the dissolved uranium was precipitated under oxic conditions in a meta-autunite-like uranyl phosphate mineral phase without supplying an additional organic phosphate substrate. In contrast to that, under anoxic conditions no mineral formation was observed at pH 4.5 and pH 6, which was clearly assigned to decreased orthophosphate release by the cells. This in turn was caused by a suppression of the indigenous phosphatase activity of the strain. The results demonstrate that changes in the metabolism of facultative anaerobic microorganisms caused by the presence or absence of oxygen can decisively influence U(VI) biomineralization. PMID:25157416

  12. Long Range Ferromagnetic Order in LaCoO3-δ epitaxial films due to the interplay of epitaxial strain and oxygen vacancy ordering

    SciTech Connect

    Mehta, Virat; Biskup, Nevenko; Arenholz, E; Varela del Arco, Maria; Suzuki, Yuri

    2015-04-23

    We demonstrate that a combination of electronic structure modification and oxygen vacancy ordering can stabilize a long-range ferromagnetic ground state in epitaxial LaCoO3 thin films. Highest saturation magnetization values are found in the thin films in tension on SrTiO3 and (La,Sr)(Al,Ta)O3 substrates and the lowest values are found in thin films in compression on LaAlO3. Electron microscopy reveals oxygen vacancy ordering to varying degrees in all samples, although samples with the highest magnetization are the most defective. Element-specific x-ray absorption techniques reveal the presence of high spin Co2+ and Co3+ as well as low spin Co3+ in different proportions depending on the strain state. The interactions among the high spin Co ions and the oxygen vacancy superstructure are correlated with the stabilization of the long-range ferromagnetic order.

  13. Study on the effect of etofenamate 10% cream in comparison with an oral NSAID in strains and sprains due to sports injuries.

    PubMed

    Vanderstraeten, G; Schuermans, P

    1990-01-01

    In this 60 patient study of sports traumatology due to football injuries, etofenamate gel proved equally effective as oral naproxen on the overall pain scores (65% none to mild pain for etofenamate versus 86% for naproxen; p greater than 0.05). The global clinical impression results have been rated as good or excellent in 44% in the naproxen group versus 50% in the etofenamate group. The incidence of side effects in the etofenamate group (3%) was lower than in the naproxen group (20%). This study demonstrates that etofenamate gel has equal efficacy as oral NSAIDS but a better side effect profile in sport injuries in football players. PMID:2094113

  14. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  15. Restricted replication of simian immunodeficiency virus strain 239 in macrophages is determined by env but is not due to restricted entry.

    PubMed Central

    Mori, K; Ringler, D J; Desrosiers, R C

    1993-01-01

    Virus derived from the infectious, pathogenic, molecular clone of simian immunodeficiency virus (SIV) called SIVmac239 replicates poorly in primary rhesus monkey alveolar macrophage cultures. Variants with three to nine amino acid changes in the envelope replicate 100 to 1,000 times more efficiently in these macrophage cultures than parental SIVmac239. Early events, including virus entry into cells, were analyzed by measuring the amounts of newly synthesized viral DNA 14 to 16 h after infection of macrophages by using a quantitative polymerase chain reaction method. SIVmac239 ws found to enter macrophages with an efficiency similar to that of the macrophage-tropic derivatives. The assay indeed measured newly synthesized viral DNA since detection was inhibited by the reverse transcriptase inhibitors azidothymidine and foscarnet and by heat inactivation of the virus stock prior to infection. Furthermore, entry of SIVmac239 and macrophage-tropic variant into macrophages was inhibited by monoclonal antibody against CD4. Analysis of the time course of viral DNA accumulation showed that although initial entry of SIVmac239 into cells occurred normally, subsequent logarithmic increases in the amounts of viral DNA associated with spread of virus through the macrophage cultures was blocked. Increasing the amount of SIVmac239 incubated with macrophages increased the amount of virus entering the cell, but this could not overcome the block to replication. Thus, restricted replication of SIVmac239 in macrophages is determined by the envelope, but surprisingly it is not due to restricted virus entry. Images PMID:7682627

  16. [Work strain by anaesthetic gas and surgical smoke due to tissue coagulation as well as safety measures in surgical operating rooms - what the surgeon needs to know].

    PubMed

    Boeckelmann, I; Sammito, S; Meyer, F

    2013-02-01

    Exposure of the respiratory tract during surgical interventions is an important topic of occupational medicine, which has only rarely been investigated. Based on a literature search, relevant information on the possible health risk is summarised. Within the operating room, an exposure of the respiratory tract to gas (volatile anaesthetics) and aerosols (smoking gas by coagulation) can occur. This exposure needs to be considered as a potential health risk if safety measures are not sufficient. Health risks comprise possible disturbances of gravidity and fertility, neurotoxicity and cancer generation. Such health risks can be prevented with primary preventive measures and can be early recognised/diagnosed by preventive investigations of occupational medicine (secondary prevention). Safety measures are developed according to the STOP principle (substitution, technical, organisatory and personal measures). Assessment of the potential danger begins with an appropriate description of the working procedure and detection of the toxic features of the drugs and medical products, which helps to determine individual exposure and to estimate risk potential. Required occupational safety measures can be derived from this and, subsequently, the work organisation can be optimised. In addition, employees in the operating room are to be instructed about the indicated preventive mode of behaviour. Due to better implementation of the above-mentioned basic principles, introduction of novel narcotics and technological developments, potential exposure of the respiratory tract within the operating room has been reduced over the last 10 years. Thus, risks for gravidity and possible disturbances of fertility by exposure to volatile narcotics are currently assessed to be low. However, available data on health risks of the chronic exposure to smoking gases are still deficient although toxic and cancerogenic organic pyrolysis products are generated. The protection effect of modern air

  17. Large enhancement of magnetic anisotropy and laser induced resistive switching effect in La0.7Sr0.3MnO3 films due to strain from BaTiO3 substrates

    NASA Astrophysics Data System (ADS)

    Kalappattil, V.; Das, R.; Srikanth, H.; Phan, M. H.; Moya, X.

    Multifunctional oxide materials are interesting for their fundamental physical properties and technological applications. Epitaxial films of La0.7Sr0.3MnO3 (LSMO) on BaTiO3 (BTO) show intriguing properties such as a giant magnetoelectric effect due to strain from BTO substrate. The LSMO film shows sharp jumps in magnetization M(T) and resistance R(T) at first-order structural phase transitions of BTO (TR-O 200K and TO-T 270 K) due to strain coupling from BTO. A temperature evolution of effective in-plane anisotropy field (HK) measured using the radio-frequency transverse susceptibility (TS) shows a sharp increase in HK around TR-O, which vanishes around TO-T.The in-plane magnetic anisotropy plays an important role in changing the magnetic and resistive states around TO-T. A switchable laser-induced resistive change of up to 300 %, which is about 10 times greater than those of conventional oxide systems, has been achieved in LSMO films using a 0.5 W violet laser just below the TO-T.The repeatability and stability of the laser-induced resistive switching effect reveal potential applications of LSMO/BTO heterostructures in developing new type of temperature sensors and memory devices. Work at USF supported by ARO Grant No. W911NF-15-1-0626.

  18. Increased prevalence of carbapenem resistant Enterobacteriaceae in hospital setting due to cross-species transmission of the blaNDM-1 element and clonal spread of progenitor resistant strains

    PubMed Central

    Wang, Xuan; Chen, Gongxiang; Wu, Xiaoyan; Wang, Liangping; Cai, Jiachang; Chan, Edward W.; Chen, Sheng; Zhang, Rong

    2015-01-01

    This study investigated the transmission characteristics of carbapenem-resistant Enterobacteriaceae (CRE) strains collected from a hospital setting in China, in which consistent emergence of CRE strains were observable during the period of May 2013 to February 2014. Among the 45 CRE isolates tested, 21 (47%) strains were found to harbor the blaNDM-1 element, and the rest of 24 CRE strains were all positive for blaKPC-2. The 21 blaNDM-1—borne strains were found to comprise multiple Enterobacteriaceae species including nine Enterobacter cloacae, three Escherichia coli, three Citrobacter freundii, two Klebsiella pneumoniae, two Klebsiella oxytoca, and two Morganella morganii strains, indicating that cross-species transmission of blaNDM-1 is a common event. Genetic analyses by PFGE and MLST showed that, with the exception of E. coli and E. cloacae, strains belonging to the same species were often genetically unrelated. In addition to blaNDM-1, several CRE strains were also found to harbor the blaKPC-2, blaVIM-1, and blaIMP-4 elements. Conjugations experiments confirmed that the majority of carbapenem resistance determinants were transferable. Taken together, our findings suggest that transmission of mobile resistance elements among members of Enterobacteriaceae and clonal spread of CRE strains may contribute synergistically to a rapid increase in the population of CRE in clinical settings, prompting a need to implement more rigorous infection control measures to arrest such vicious transmission cycle in CRE-prevalent areas. PMID:26136735

  19. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1997-01-01

    Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

  20. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  1. First detection of Aspergillus fumigatus azole-resistant strain due to Cyp51A TR46/Y121F/T289A in an azole-naive patient in Spain.

    PubMed

    Pelaez, T; Monteiro, M C; Garcia-Rubio, R; Bouza, E; Gomez-Lopez, A; Mellado, E

    2015-07-01

    We report the first isolation of a voriconazole-resistant Aspergillus fumigatus strain harbouring the azole resistance mechanism TR46/Y121F/T289A, recovered from an azole-naive patient in Spain with chronic obstructive pulmonary disease. This new finding in Spain suggests the spread of this resistance mechanism and reinforces the need for antifungal susceptibility surveillance. PMID:26082842

  2. The multiple forms of trypsin-like activity present in various strains of Porphyromonas gingivalis are due to the presence of either Arg-gingipain or Lys-gingipain.

    PubMed Central

    Potempa, J; Pike, R; Travis, J

    1995-01-01

    Porphyromonas gingivalis contains high concentrations of numerous cysteine proteinases with trypsin-like activity which have been implicated as important virulence factors in adult-onset periodontitis. We have analyzed the subfractions of six P. gingivalis strains for the presence of arginine-X- and lysine-X-specific proteinases (Arg-gingipain [RGP] and Lys-gingipain [KGP]) previously purified from P. gingivalis H66. Western blot (immunoblot) analysis using antibodies produced against RGP and the N-terminal peptides of RGP or the catalytic subunit of KGP indicated that these enzymes are synthesized by the strains studied and exist as multiple molecular mass species. The major forms of RGP were identified as 110-, 95-, 70- to 90-, and 50-kDa proteins, the first two being a complex of the 50-kDa catalytic subunit with hemagglutinins, with or without an added membrane anchorage peptide. The other forms are single-chain enzymes. While the 95- and 50-kDa RGP were found predominantly in culture medium, the 110- and 70- to 90-kDa forms associated with membranous fractions of the bacteria. The predominant form of KGP in all strains was a complex of the 60-kDa catalytic domain with hemagglutinins, and vesicle- and membrane-associated KGP was about 15 kDa larger than the 105-kDa enzyme present in culture media. These data explain the apparent complexity of P. gingivalis proteinases and indicate that in all strains tested there are two identical enzymes, one with arginine-X specificity and the other with lysine-X specificity, which, working in concert, are responsible for the trypsin-like activity associated with this bacterium. PMID:7890369

  3. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

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

  4. Multiple-Antibiotic Resistance in Salmonella enterica Serotype Paratyphi B Isolates Collected in France between 2000 and 2003 Is Due Mainly to Strains Harboring Salmonella Genomic Islands 1, 1-B, and 1-C

    PubMed Central

    Weill, François-Xavier; Fabre, Laëtitia; Grandry, Bernadette; Grimont, Patrick A. D.; Casin, Isabelle

    2005-01-01

    This study was conducted to investigate the occurrence of multiple-antibiotic resistance among 261 clinical isolates of Salmonella enterica serotype Paratyphi B strains collected between 2000 and 2003 through the network of the French National Reference Center for Salmonella. The 47 multidrug-resistant (MDR) isolates identified (18%), were characterized on the basis of the presence of several resistance genes (blaTEM, blaPSE-1, blaCTX-M, floR, aadA2, qacEΔ1, and sul1), the presence of Salmonella genomic island 1 (SGI1) by PCR mapping and hybridization, and the clonality of these isolates by several molecular (ribotyping, IS200 profiling, and pulsed-field gel electrophoresis [PFGE]) and phage typing methods. The results of PCR and Southern blot experiments indicated that 39 (83%) of the 47 S. enterica serotype Paratyphi B biotype Java MDR isolates possessed the SGI1 cluster (MDR/SGI1). Among these 39 MDR/SGI1 isolates, only 3 contained variations in SGI1, SGI1-B (n = 1) and SGI1-C (n = 2). The 39 MDR/SGI1 isolates showed the same specific PstI-IS200 profile 1, which contained seven copies from 2.6 to 18 kb. Two PstI ribotypes were found in MDR/SGI1 isolates, RP1 (n = 38) and RP6 (n = 1). Ribotype RP1 was also found in two susceptible strains. Analysis by PFGE using XbaI revealed that all the MDR/SGI1 isolates were grouped in two related clusters, with a similarity percentage of 82%. Isolation of MDR/SGI1 isolates in France was observed mainly between the second quarter of 2001 and the end of 2002. The source of the contamination has not been identified to date. A single isolate possessing the extended-spectrum β-lactamase blaCTX-M-15 gene was also identified during the study. PMID:15980351

  5. Decreased fecal corticosterone levels due to domestication: a comparison between the white-backed Munia (Lonchura striata) and its domesticated strain, the Bengalese finch (Lonchura striata var. domestica) with a suggestion for complex song evolution.

    PubMed

    Suzuki, Kenta; Yamada, Hiroko; Kobayashi, Tetsuya; Okanoya, Kazuo

    2012-11-01

    The Bengalese finch (BF; Lonchura striata var. domestica) is a domesticated strain of the white-backed munia (WBM; Lonchura striata). Environmental stresses activate the hypothalamic-pituitary-adrenal (HPA) axis and release corticosterone (CORT). We hypothesized that domesticated songbirds have reduced CORT levels because of reduced levels of environmental stresses (compared to wild conditions) and reductions in the role of CORT, which is necessary for survival in the wild. However, no study has examined the effects of domestication on songbird CORT levels. To explore the domestication effects, we compared CORT levels between domesticated BFs and their wild ancestors WBMs. We also compared CORT levels between bought and aviary-raised BFs, and between wild-caught and captive-raised WBMs to examine the influence of being raised. However, blood collection causes stress, which affects endocrine dynamics and makes continuous sampling difficult in small birds. Therefore, we used a non-invasive method to measure fecal CORT. Parallelism between diluted fecal extracts and a CORT standard, extraction efficiency, and ACTH challenge demonstrated the effectiveness of this method. This study demonstrates that BFs have lower fecal CORT than do WBMs, regardless of whether the WBMs were wild-caught or captive-raised. In addition, BFs sing more complex songs than WBMs. Considerable evidence suggests that song complexity is related to CORT levels. Previously, we found that the corticosteroid receptors were expressed in song-control areas of the BF brain. Based on these results, we hypothesize that reduced CORT levels through domestication might be one factor allowing for the development of more complex songs in BFs. PMID:22927235

  6. Inhomogeneous strains in small particles

    NASA Astrophysics Data System (ADS)

    Marks, L. D.

    1985-02-01

    This paper considers the evidence for strains in small particles. Firstly, the dynamical electron diffraction theory for dark field imaging of small particles is briefly reviewed, considering primarily the effects of strain on wedge crystals and identifying the fingerprint of strain contrast effects under strong beam conditions. Evidence included herein and from published papers by other authors clearly shows inhomogeneous strain effects in both multiply twinned particles and single crystals. Considering these results and earlier reports of lattice parameter changes, there are problems with the uniqueness of these analyses, and the strains in the small single crystals are thought more likely to be due to interfacial stresses or contaminants than any intrinsic particle effect; there are so many different origins of this type of strain that we cannot with confidence isolate a unique source. It is emphasised that the uniqueness of any interpretation of experimental results from small particles must be very carefully considered.

  7. Extended-Spectrum-β-Lactamase-Producing Escherichia coli as a Cause of Pediatric Infections: Report of a Neonatal Intensive Care Unit Outbreak Due to a CTX-M-14-Producing Strain

    PubMed Central

    Oteo, Jesús; Cercenado, Emilia; Fernández-Romero, Sara; Saéz, David; Padilla, Belén; Zamora, Elena; Cuevas, Oscar; Bautista, Verónica

    2012-01-01

    Little information is available about pediatric infections caused by extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli. We characterized an outbreak caused by a CTX-M-14-producing E. coli isolate in a neonatal intensive care unit (NICU) and studied other infections caused by ESBL-producing E. coli in non-NICU pediatric units. All children ≤4 years old who were infected or colonized by ESBL-producing E. coli isolates between January 2009 and September 2010 were included. Molecular epidemiology was studied by phylogroup analysis, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing. Antibiotic resistance genes were analyzed by PCR and sequencing. Plasmids were studied by PFGE with S1 nuclease digestion and by incompatibility group analysis using a PCR-based replicon-typing scheme. Of the ESBL-producing E. coli isolates colonizing or infecting the 30 newborns, identical PFGE results were observed for 21 (70%) isolates, which were classified as CTX-M-14-producing E. coli of ST23 phylogroup A. blaCTX-M-14a was linked to ISEcp1 and was carried on an ∼80-bp IncK plasmid. A smaller ongoing outbreak due to SHV-12-producing ST131 E. coli was also identified in the same NICU. Fifteen additional infections with ESBL-producing E. coli were identified in non-NICU pediatric units, but none was caused by the CTX-M-14-producing E. coli epidemic clone. Overall, CTX-M-14 (71.1%), CTX-M-15 (13.3%), and SHV-12 (13.3%) were the most important ESBLs causing pediatric infections in this study. Infections of newborns with CTX-M-14-producing E. coli were caused by both clonal and nonclonal isolates. PMID:21986825

  8. MEMS Graphene Strain Sensor

    NASA Astrophysics Data System (ADS)

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  9. Piezoelectric field in strained GaAs.

    SciTech Connect

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

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

  10. Enhancement of two dimensional electron gas concentrations due to Si{sub 3}N{sub 4} passivation on Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructure: strain and interface capacitance analysis

    SciTech Connect

    Dinara, Syed Mukulika Jana, Sanjay Kr.; Ghosh, Saptarsi; Mukhopadhyay, Partha; Kumar, Rahul; Chakraborty, Apurba; Biswas, Dhrubes; Bhattacharya, Sekhar

    2015-04-15

    Enhancement of two dimensional electron gas (2DEG) concentrations at Al{sub 0.3}Ga{sub 0.7}N/GaN hetero interface after a-Si{sub 3}N{sub 4} (SiN) passivation has been investigated from non-destructive High Resolution X-ray Diffraction (HRXRD) analysis, depletion depth and capacitance-voltage (C-V) profile measurement. The crystalline quality and strained in-plane lattice parameters of Al{sub 0.3}Ga{sub 0.7}N and GaN were evaluated from double axis (002) symmetric (ω-2θ) diffraction scan and double axis (105) asymmetric reciprocal space mapping (DA RSM) which revealed that the tensile strain of the Al{sub 0.3}Ga{sub 0.7}N layer increased by 15.6% after SiN passivation. In accordance with the predictions from theoretical solution of Schrödinger-Poisson’s equations, both electrochemical capacitance voltage (ECV) depletion depth profile and C-V characteristics analyses were performed which implied effective 9.5% increase in 2DEG carrier density after passivation. The enhancement of polarization charges results from increased tensile strain in the Al{sub 0.3}Ga{sub 0.7}N layer and also due to the decreased surface states at the interface of SiN/Al{sub 0.3}Ga{sub 0.7}N layer, effectively improving the carrier confinement at the interface.

  11. Hip flexor strain - aftercare

    MedlinePlus

    Pulled hip flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  12. Strainrange partitioning: A total strain range version

    NASA Technical Reports Server (NTRS)

    Halford, G. R.; Saltsman, J. F.

    1983-01-01

    Procedures are presented for expressing the Strainrange Partitioning (SRP) method for creep fatigue life prediction in terms of total strain range. Inelastic and elastic strain-range - life relations are summed to give total strain-range - life relations. The life components due to inelastic strains are dealt with using conventional SRP procedures while the life components due to elastic strains are expressed as families of time-dependent terms for each type of SRP cycle. Cyclic constitutive material behavior plays an important role in establishing the elastic strain-range - life relations as well as the partitioning of the inelastic strains. To apply the approach, however, it is not necessary to have to determine the magnitude of the inelastic strain range. The total strain SRP approach is evaluated and verified using two nickel base superalloys, AF2-1DA and Rene 95. Excellent agreement is demonstrated between observed and predicted cyclic lifetimes with 70 to 80 percent of the predicted lives falling within factors of two of the observed lives. The total strain-range SRP approach should be of considerable practical value to designers who are faced with creep-fatigue problems for which the inelastic strains cannot be calculated with sufficient accuracy to make reliable life predictions by the conventional inelastic strain range SRP approach.

  13. An experimental evaluation of apparent strain from foil strain gauges attached to carbon composite substrates

    NASA Technical Reports Server (NTRS)

    Scott, B. R.; Lanius, S. J.; Auer, C. W.

    1987-01-01

    An experimental evaluation of apparent thermal strains is conducted using various combinations of substrate/gauge/attachment structure and redundant high temperature extensometry. It is found that the extensometry could either confirm independent measurements of the substrate's thermal expansion, or quantify nonzero mechanical strains resulting from uncertain material behavior and boundary conditions. Apparent strain and thermal expansion behavior data can then be used to modify the raw strain measurements in order to determine either stress producing or total strains. Limitation of the correction procedure for the three selected strain gauges is noted which is due to relatively large gauge/attachment variability.

  14. Progress in optical strain measurement system development

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.; Qaqish, Walid

    1987-01-01

    A laser speckle strain measurement system has been built and tested for the NASA Lewis Research Center. The system is based on a speckle shift technique, which automatically corrects for error due to rigid body motion, and provides a near real time measure of strain. The first stage of a multiphase effort to develop an optical strain gauge capable of mapping in two dimensions the strain on the surface of a hot specimen is discussed. The objectives of this first phase have been to provide a noncontact, one-dimensional, differential strain gauge for experimental purposes, and to determine the maximum open air temperature limit of the system.

  15. Strain balanced quantum posts

    SciTech Connect

    Alonso-Alvarez, D.; Alen, B.; Ripalda, J. M.; Llorens, J. M.; Taboada, A. G.; Briones, F.; Roldan, M. A.; Hernandez-Saz, J.; Hernandez-Maldonado, D.; Herrera, M.; Molina, S. I.

    2011-04-25

    Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here, we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.

  16. Geobacteraceae strains and methods

    DOEpatents

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  17. Muscle strain (image)

    MedlinePlus

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

  18. Muscle strain treatment

    MedlinePlus

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

  19. Strains and Sprains

    MedlinePlus

    ... Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken Bones, Sprains, and Strains Strains and Sprains ... Pain Going to a Physical Therapist Hamstring Strain Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries ...

  20. Program Calibrates Strain Gauges

    NASA Technical Reports Server (NTRS)

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  1. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  2. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  3. Distributed strain monitoring for bridges: temperature effects

    NASA Astrophysics Data System (ADS)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

    To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic strain sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for strain to be measured with the same accuracy and gage lengths as conventional strain sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed strain sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. Strain data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the strain measurements are affected by the bridge behavior as a whole. The strain measurements due to temperature are compared to strain measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and strain changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.

  4. Mechanical strain effects on black phosphorus nanoresonators.

    PubMed

    Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon

    2016-01-14

    We perform classical molecular dynamics simulations to investigate the effects of mechanical strain on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. PMID:26649476

  5. Papilledema Due to Mirtazapine

    PubMed Central

    Ceylan, Mehmet Emin; Evrensel, Alper; Cömert, Gökçe

    2016-01-01

    Background: Mirtazapine is a tetracyclic antidepressant that enhances both noradrenergic and serotonergic transmission. The most common cause of papilledema is increased intracranial pressure due to brain tumor. Also it may occur as a result of idiopathic intracranial hypertension (IIH, pseudo tumor cerebri). Moreover, papilledema may also develop due to retinitis, vasculitis, Graves’ disease, hypertension, leukemia, lymphoma, diabetes mellitus and radiation. Case Report: In this article, a patient who developed papilledema while under treatment with mirtazapine (30 mg/day) for two years and recovered with termination of mirtazapine treatment was discussed to draw the attention of clinicians to this side effect of mirtazapine. Conclusion: Idiopathic intracranial hypertension and papilledema due to psychotropic drugs has been reported in the literature. Mirtazapine may rarely cause peripheral edema. However, papilledema due to mirtazapine has not been previously reported. Although papilledema is a very rare side effect of an antidepressant treatment, fundoscopic examinations of patients must be performed regularly. PMID:27308085

  6. Optical Strain Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lant, C. T.

    1985-01-01

    Investigations of physical phenomena affecting the durability of SSME components require measurement systems operational in hostile environments. The need for such instrumentation caused the definition and operation of an optical strain measurement system. This optical strain measurement system based on the speckle shift method is being developed. This is a noncontact, automatic method of measuring surface strain in one dimension that corrects for error due to rigid body motion. It provides a gauge length of 1 to 2 mm and allows the region of interest on the test specimen to be mapped point by point. The output is a graphics map of the points inspected on the specimen; data points is stored in quasi-real time. This is the first phase of a multiphase effort in optical strain measurement. The speckle pattern created by the test specimen is interpreted as high order interference fringes resulting from a random diffraction grating, being the natural surface roughness of the specimen. Strain induced on the specimen causes a change in spacing of the surface roughness, which in turn shifts the position of the interference pattern (speckles).

  7. Miniature biaxial strain transducer

    NASA Technical Reports Server (NTRS)

    Hoffman, I. S. (Inventor)

    1976-01-01

    A reusable miniature strain transducer for use in the measurement of static or quasi-static, high level, biaxial strain on the surface of test specimens or structures was studied. Two cantilever arms, constructed by machining the material to appropriate flexibility, are self-aligning and constitute the transducing elements of the device. Used in conjunction with strain gages, the device enables testing beyond normal gage limits for high strains and number of load cycles. The device does not require conversion computations since the electrical output of the strain gages is directly proportional to the strain measured.

  8. Providers get their due.

    PubMed

    Morrissey, J

    1994-11-01

    Providers are getting their due, but only after employing computer software programs to help sort through the complex managed-care contracts they've negotiated. More and more accounting departments are relying on contract management systems to ensure accurate billing. PMID:10138187

  9. Paying Their Dues.

    ERIC Educational Resources Information Center

    Scalzo, Teresa

    1995-01-01

    Some colleges and universities have found that alumni prefer to have ownership of their alumni association, and such a membership program can raise revenues for the institution while providing a valuable communication tool. A strong dues program can work well with an annual giving campaign. A variety of membership structures is possible. Details…

  10. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  11. Strains and Sprains

    MedlinePlus

    ... move the injured part, and you might even think you have broken a bone. How Does a Strain or Sprain Happen? Strains often happen when you put a lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains may be more likely to happen if ...

  12. High strain rate damage of Carrara marble

    NASA Astrophysics Data System (ADS)

    Doan, Mai-Linh; Billi, Andrea

    2011-10-01

    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  13. Human due diligence.

    PubMed

    Harding, David; Rouse, Ted

    2007-04-01

    Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly. PMID:17432159

  14. Nanoscale strain mapping in battery nanostructures

    SciTech Connect

    Ulvestad, A. Kim, J. W.; Dietze, S. H.; Shpyrko, O. G.; Cho, H. M.; Meng, Y. S.; Harder, R.; Fohtung, E.

    2014-02-17

    Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi{sub 0.5}Mn{sub 1.5}O{sub 4−δ} cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn{sup 3+}. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

  15. Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition

    PubMed Central

    Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.

    2015-01-01

    Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential. PMID:26529510

  16. Hydraulic Calibrator for Strain-Gauge Balances

    NASA Technical Reports Server (NTRS)

    Skelly, Kenneth; Ballard, John

    1987-01-01

    Instrument for calibrating strain-gauge balances uses hydraulic actuators and load cells. Eliminates effects of nonparallelism, nonperpendicularity, and changes of cable directions upon vector sums of applied forces. Errors due to cable stretching, pulley friction, and weight inaccuracy also eliminated. New instrument rugged and transportable. Set up quickly. Developed to apply known loads to wind-tunnel models with encapsulated strain-gauge balances, also adapted for use in calibrating dynamometers, load sensors on machinery and laboratory instruments.

  17. Strain gage balances and buffet gages

    NASA Technical Reports Server (NTRS)

    Ferris, A. T.

    1983-01-01

    One-piece strain gage force balances were developed for use in the National Transonic Facility (NTF). This was accomplished by studying the effects of the cryogenic environment on materials, strain gages, cements, solders, and moisture proofing agents, and selecting those that minimized strain gage output changes due to temperature. In addition, because of the higher loads that may be imposed by the NTF, these balances are designed to carry a larger load for a given diameter than conventional balances. Full cryogenic calibrations were accomplished, and wind tunnel results that were obtained from the Langley 0-3-Meter Transonic Cryogenic Tunnel were used to verify laboratory test results.

  18. Stretchable and highly sensitive graphene-on-polymer strain sensors

    PubMed Central

    Li, Xiao; Zhang, Rujing; Yu, Wenjian; Wang, Kunlin; Wei, Jinquan; Wu, Dehai; Cao, Anyuan; Li, Zhihong; Cheng, Yao; Zheng, Quanshui; Ruoff, Rodney S.; Zhu, Hongwei

    2012-01-01

    The use of nanomaterials for strain sensors has attracted attention due to their unique electromechanical properties. However, nanomaterials have yet to overcome many technological obstacles and thus are not yet the preferred material for strain sensors. In this work, we investigated graphene woven fabrics (GWFs) for strain sensing. Different than graphene films, GWFs undergo significant changes in their polycrystalline structures along with high-density crack formation and propagation mechanically deformed. The electrical resistance of GWFs increases exponentially with tensile strain with gauge factors of ~103 under 2~6% strains and ~106 under higher strains that are the highest thus far reported, due to its woven mesh configuration and fracture behavior, making it an ideal structure for sensing tensile deformation by changes in strain. The main mechanism is investigated, resulting in a theoretical model that predicts very well the observed behavior. PMID:23162694

  19. Can strain magnetize light?

    NASA Astrophysics Data System (ADS)

    2013-02-01

    Strain in photonic structures can induce pseudomagnetic fields and Landau levels. Nature Photonics spoke to Mordechai Segev, Mikael Rechtsman, Alexander Szameit and Julia Zeuner about their unique approach.

  20. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1986-01-01

    One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

  1. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  2. Introducing lattice strain to graphene encapsulated in hBN

    NASA Astrophysics Data System (ADS)

    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.

  3. Geodetic Strain Analysis Tool

    NASA Technical Reports Server (NTRS)

    Kedar, Sharon; Baxter, Sean C.; Parker, Jay W.; Webb, Frank H.; Owen, Susan E.; Sibthorpe, Anthony J.; Dong, Danan

    2011-01-01

    A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user s data. Users may change parameters on-the-fly and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available. This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the "best practices" strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.

  4. Giant Reduction of Charge Carrier Mobility in Strained Graphene

    NASA Astrophysics Data System (ADS)

    Shah, Raheel; Mohiuddin, Tariq M. G.; Singh, Ram N.

    2013-01-01

    Impact of induced strain on charge carrier mobility is investigated for a monolayer graphene sheet. The unsymmetrical hopping parameters between nearest neighbor atoms which emanate from induced strain are included in the density of states description. Mobility is then computed within the Born approximation by including three scattering mechanisms; charged impurity, surface roughness and lattice phonons interaction. Unlike its strained silicon counterpart, simulations reveal a significant drop in mobility for graphene with increasing strain. Additionally, mobility anisotropy is observed along the zigzag and armchair orientations. The prime reason for the drop in mobility can be attributed to the change in Fermi velocity due to strain induced distortions in the graphene honeycomb lattice.

  5. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  6. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  7. Negative strain rate sensitivity in bulk metallic glass and its similarities with the dynamic strain aging effect during deformation

    SciTech Connect

    Dalla Torre, Florian H.; Dubach, Alban; Siegrist, Marco E.; Loeffler, Joerg F.

    2006-08-28

    Detailed investigations were carried out on the deformation behavior of Zr-based monolithic bulk metallic glass and bulk metallic glass matrix composites. The latter, due to splitting and multiplication of shear bands, exhibits larger compressive strains than the former, without significant loss of strength. Serrated flow in conjunction with a negative strain rate sensitivity was observed in both materials. This observation, together with an increase in stress drops with increasing strain and their decrease with increasing strain rate, indicates phenomenologically close similarities with the dynamic strain aging deformation mechanism known for crystalline solids. The micromechanical mechanism of a shear event is discussed in light of these results.

  8. Determining Micromechanical Strain in Nitinol

    SciTech Connect

    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.

  9. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  10. Mechanochromic polyurethane strain sensor

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Khapli, S.; Peterson, S. D.; Porfiri, M.

    2014-08-01

    In this Letter, we study the mechanical and optical response of a thermoplastic polyurethane blended with 0.5 wt. % of bis(benzoxazolyl)stilbene dye. The mechanochromic behavior of the material is characterized in a uniaxial stress-relaxation test by simultaneously acquiring the applied force, mechanical deformation, and fluorescence emission. To offer insight into the stress-strain response of the polymer-dye blend, we adapt a classical nonlinear constitutive behavior for elastomeric materials that accounts for stress-induced softening. We correlate the fluorescent response with the mechanical strain to demonstrate the possibility of accurate strain sensing for a broad range of deformations during both loading and unloading.

  11. Strain gauge installation tool

    SciTech Connect

    Conard, Lisa Marie

    1997-12-01

    A tool and a method for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  12. Revisiting borehole strain, typhoons, and slow earthquakes using quantitative estimates of precipitation-induced strain changes

    NASA Astrophysics Data System (ADS)

    Hsu, Ya-Ju; Chang, Yuan-Shu; Liu, Chi-Ching; Lee, Hsin-Ming; Linde, Alan T.; Sacks, Selwyn I.; Kitagawa, Genshio; Chen, Yue-Gau

    2015-06-01

    Taiwan experiences high deformation rates, particularly along its eastern margin where a shortening rate of about 30 mm/yr is experienced in the Longitudinal Valley and the Coastal Range. Four Sacks-Evertson borehole strainmeters have been installed in this area since 2003. Liu et al. (2009) proposed that a number of strain transient events, primarily coincident with low-barometric pressure during passages of typhoons, were due to deep-triggered slow slip. Here we extend that investigation with a quantitative analysis of the strain responses to precipitation as well as barometric pressure and the Earth tides in order to isolate tectonic source effects. Estimates of the strain responses to barometric pressure and groundwater level changes for the different stations vary over the ranges -1 to -3 nanostrain/millibar(hPa) and -0.3 to -1.0 nanostrain/hPa, respectively, consistent with theoretical values derived using Hooke's law. Liu et al. (2009) noted that during some typhoons, including at least one with very heavy rainfall, the observed strain changes were consistent with only barometric forcing. By considering a more extensive data set, we now find that the strain response to rainfall is about -5.1 nanostrain/hPa. A larger strain response to rainfall compared to that to air pressure and water level may be associated with an additional strain from fluid pressure changes that take place due to infiltration of precipitation. Using a state-space model, we remove the strain response to rainfall, in addition to those due to air pressure changes and the Earth tides, and investigate whether corrected strain changes are related to environmental disturbances or tectonic-original motions. The majority of strain changes attributed to slow earthquakes seem rather to be associated with environmental factors. However, some events show remaining strain changes after all corrections. These events include strain polarity changes during passages of typhoons (a characteristic that is

  13. The Course of Due Process.

    ERIC Educational Resources Information Center

    Getty, Laura A.; Summy, Sarah E.

    2004-01-01

    Discussion of due process rights for children with disabilities considers common issues leading to due process requests, due process procedures, hearing officers, procedural violations, effects of due process meetings, and areas for improvement (i.e., accountability, paperwork). Tables list categories of procedural violations with examples and…

  14. Attaching strain transducers to fragile materials

    NASA Technical Reports Server (NTRS)

    Duggan, M. F.

    1979-01-01

    A-shaped clamp prevents damage to thin, brittle specimens and supports displacement transducer away from heated zone. Also it defines reference points for strain measurement on specimen surface thus preventing specimen cracking due to unequal thermal expansion between clamp and holder.

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

    PubMed

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

    2016-08-01

    The promising and versatile applications of low dimensional materials are largely due to their surface properties, which along with their underlying electronic structures have been well studied. However, these materials may not be directly useful for applications requiring properties other than their natal ones. In recent years, strain has been shown to be an additionally useful handle to tune the physical and chemical properties of materials by changing their geometric and electronic structures. The strategies for producing strain are summarized. Then, the electronic structure of quasi-two dimensional layered non-metallic materials (e.g., graphene, MX2, BP, Ge nanosheets) under strain are discussed. Later, the strain effects on catalytic properties of metal-catalyst loaded with strain are focused on. Both experimental and computational perspectives for dealing with strained systems are covered. Finally, an outlook on engineering surface properties utilizing strain is provided. PMID:27376498

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  17. What Are Sprains and Strains?

    MedlinePlus

    ... sprain, one or more ligaments is stretched or torn. What Causes a Sprain? Where Do Sprains Usually ... strain, a muscle or tendon is stretched or torn. What Causes Strains? A strain is caused by ...

  18. Nanowires enabling strained photovoltaics

    SciTech Connect

    Greil, J.; Bertagnolli, E.; Lugstein, A.; Birner, S.

    2014-04-21

    Photovoltaic nano-devices have largely been relying on charge separation in conventional p-n junctions. Junction formation via doping, however, imposes major challenges in process control. Here, we report on a concept for photovoltaic energy conversion at the nano scale without the need for intentional doping. Our approach relies on charge carrier separation in inhomogeneously strained germanium nanowires (Ge NWs). This concept utilizes the strain-induced gradient in bandgap along tapered NWs. Experimental data confirms the feasibility of strain-induced charge separation in individual vapor-liquid-solid grown Ge NW devices with an internal quantum efficiency of ∼5%. The charge separation mechanism, though, is not inherently limited to a distinct material. Our work establishes a class of photovoltaic nano-devices with its opto-electronic properties engineered by size, shape, and applied strain.

  19. Sprains and Strains

    MedlinePlus

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  20. A high-strain-rate superplastic ceramic.

    PubMed

    Kim, B N; Hiraga, K; Morita, K; Sakka, Y

    2001-09-20

    High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great technological interest for the shape-forming of engineering materials. High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates of the order of 10-5 to 10-4 s-1 for most oxides and nitrides with the presence of intergranular cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminate spinel and alpha-alumina phases exhibits superplasticity at strain rates up to 1 s-1. The composite also exhibits a large tensile elongation, exceeding 1,050 per cent for a strain rate of 0.4 s-1. The tensile flow behaviour and deformed microstructure of the material indicate that superplasticity is due to a combination of limited grain growth in the constitutive phases and the intervention of dislocation-induced plasticity in the zirconium oxide phase. We suggest that the present results hold promise for the application of shape-forming technologies to ceramic materials. PMID:11565026

  1. Ecoepidemics with Two Strains: Diseased Prey.

    NASA Astrophysics Data System (ADS)

    Elena, Elisa; Grammauro, Maria; Venturino, Ezio

    2011-09-01

    In this work we present a minimal model for an ecoepidemic situation with two diseases affecting the prey population. The main assumptions are the following ones. The predators recognize and hunt only the healthy prey. An infected prey of one strain becomes immune to the other one. The major finding shows that the two strains cannot simultaneously thrive in the system, contrary to the standard assumptions in epidemiology. But this rather unexpected and remarkable result, paralleling another one when the epidemics affects the predators, is most likely due to the assumptions made.

  2. Annihilation of strained vortices

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshifumi

    2014-11-01

    As an initial stage of vortex reconnection, approach of nearly anti-parallel vortices has often been observed experimentally and studied numerically. Inspired by the recent experiment by Kleckner and Irvine on the dynamics of knotted vortices, we have studied the motion of two anti-parellel Burgers vortices driven by an axisymmetric linear straining field. We first extend the Burgers vortex solution which is a steady exact solution of the Navier-Stokes equation to a time-dependent exact solution. Then by superposing two such solutions, we investigate the annihilation process analytically. We can demonstrate that during the annihilation process the total vorticity decays exponentially on a time-scale proportional to the inverse of the rate of strain, even as the kinematic viscosity tends to 0. The analytic results are compared with the numerical simulations of two strained vortices with the vortex-vortex nonlinear interaction by Buntine and Pullin.

  3. The atomic strain tensor

    SciTech Connect

    Mott, P.H.; Argon, A.S. ); Suter, U.W. Massachusetts Institute of Technology, Cambridge, MA )

    1992-07-01

    A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated in to Delaunay tetrahedra, identifying interstices, and Voronoi polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronoi polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronoi polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level. 6 refs. 10 figs.

  4. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  5. Diffusion on strained surfaces

    NASA Astrophysics Data System (ADS)

    Schroeder, M.; Wolf, D. E.

    1997-03-01

    The change of diffusion kinetics when elastic fields are present is discussed for diffusion on (001) surfaces of simple cubic, fcc and bcc lattices. All particles interact pairwise with a Lennard-Jones potential. The simple cubic lattice was stabilized by an anisotropic prefactor. It is found that generically compressive strain enhances diffusion whereas tensile strain increases the activation barrier. An approximately linear dependence of the barrier in a wide range of misfits is found. In heteroepitaxy, diffusion on top of large clusters is inhomogeneous and anisotropic. The kinetics close to edges and centers of islands are remarkably different. In many cases changes of binding energies are small compared to those of saddle point energies. Thermodynamic arguments (minimization of free energy) are not appropriate to describe diffusion on strained surfaces in these cases.

  6. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  7. The apparent strain stability and repeatability of a BCL3 resistance strain gage

    NASA Astrophysics Data System (ADS)

    Lei, Jih-Fen

    1991-02-01

    Experiments were conducted at NASA-Lewis to study the effect of microstructural instability on the apparent strain stability and reproducibility of a BCL3 resistance strain gage. The resistance drift of the gage at various temperatures in the phase transition temperature range (PTTR) was measured. The effects of the heating and cooling rates with which the gage passed through the PTTR on the apparent strain characteristics of the gage were also studied. BCL3 gage, like other Fe-Cr-Al based gages, exhibited apparent strain instability in the temperature range of 700 to 1100 F due to the reversible microstructural transition the gage materials experienced in this temperature range. The BCL3 gage had a maximum apparent strain drift in the neighborhood of 770 F with an average drift rate of approx. -440 microstrain/hr in 2 hrs. The use of the BCL3 gage as well as other Fe-Cl-Al based gages for static strain measurements within the PTTR should be avoided unless the time durations in the PTTR are small enough to introduce a neglible drift. The microstructure transition that the BCL3 gage underwent occurred in the temperature range of 750 to 1050 F during heating and around 1000 to 800 F during cooling. The heating rate, and, in particular, the cooling rate with which the gage passed through the PTTR affected the shape and the repeatability of the apparent strain curve of the gage.

  8. Microstructural changes, steady-state deformation and strain localisation during large strain deformation of rocks

    NASA Astrophysics Data System (ADS)

    Barnhoorn, A.

    2012-04-01

    Ductile deformation in the Earth's crust and mantle is often concentrated in narrow shear zones. These shear zones play a fundamental role in the deformation dynamics of the earth's lithosphere during mountain building, subduction and continental break-up. Shear zones exhibit large amounts of strain with an increase in strain from the edge to the center of the shear zone. Those large strains are often accompanied with large changes in microstructure due to processes such as dynamic recrystallization, grain size refinement, development of strong foliations, development of crystallographic preferred orientations, weakening of the rock as well as progressive localisation of the deformation into more and more concentrated zones. The interplay between all those different processes produce the various microstructures that are often studied in natural shear zones to assess the deformation conditions and history of plate tectonic processes. Experimental deformation studies under controlled conditions are used to produce relationships between the different processes active in shear zones (rheology, microstructural changes, and CPO development) in order to make those quantitative inferences on natural shear zones, Here I will present the outcomes from large strain torsion experiments at elevated temperatures and pressures on monophase calcitic rocks showing that very large strains are needed before true steady-state conditions in rocks are attained. Continuous changes in crystallographic preferred orientations and continuous dynamic recrystallization by grain boundary migration and subgrain rotation recrystallization occur up to the largest shear strains achieved in the study (shear strain of 50). Dynamic recrystallization from an undeformed coarse-grained calcite rock types towards a fine-grained ultramylonite is accompanied by a modest (~20%) weakening of the rock. However, this modest weakening never caused strain localisation in the samples. In contrast to the

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

    PubMed Central

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

    2014-01-01

    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. PMID:25170683

  10. ConStrains identifies microbial strains in metagenomic datasets

    PubMed Central

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-01-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived data sets provides insights into microbial community dynamics. PMID:26344404

  11. Local Strain Evaluation of Strained-SOI Structures

    NASA Astrophysics Data System (ADS)

    Usuda, Koji; Mizuno, Tomohisa; Numata, Toshinori; Tezuka, Tsutomu; Sugiyama, Naoharu; Moriyama, Yoshihiko; Nakaharai, Shu; Takagi, Shin-Ichi

    The strain relaxation within a strained-Si on SiGe on insulator (SGOI) structure might be one of the key issues in development of strained-Si MOSFET devices for high-performance ULSIs. In order to investigate the strain relaxation within the thin strained-Si layers, a new characterization technique to directly evaluate a local strain variation in the layers is required. Hence, we have developed the nano-beam electron diffraction (NBD) method which has a lateral resolution of 10 nm and a strain resolution of 0.1%. In this paper, we discuss a detailed investigation of whether the NBD method could be utilized to clarify a strain in a strained-Si layer on the SGOI structures.

  12. ConStrains identifies microbial strains in metagenomic datasets.

    PubMed

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-10-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  13. Numerical calculations of strained premixed laminar flames

    NASA Astrophysics Data System (ADS)

    Darabiha, N.; Candel, S.; Marble, F. E.

    The structure of a strained laminar flame in the vicinity of a stagnation point is examined numerically. The stagnation point is established by the counterflow of fresh mixture and hot products. This situation is described by standard reactive boundary layer equations. The numerical scheme used to solve the similar boundary layer equations put in F-V form (block-implicit) is an adaptation of the schemes proposed by Blottner (1979). The calculations are performed first on an uniform grid and then confirmed with an adaptive grid method due to Smooke (1982). Numerical calculations allow an exact description of the flame structure in physical and also reduced coordinates. Predictions of Libby and Williams (1982) for high and intermediate values of the strain rate based on activation energy asymptotics are confirmed. For low strain rates (ordinary unstrained laminar flame) the mass rate of reaction per unit flame area differs from that obtained by activation energy asymptotics.

  14. The breaking strain of neutron star crust

    SciTech Connect

    Kadau, Kai; Horowitz, C J

    2009-01-01

    Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking strain of neutron star crust. With multimillion ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the breaking strain of pure single crystals is very large and that impurities, defects, and grain boundaries only modestly reduce the breaking strain to around 0.1. Due to the collective behavior of the ions during failure found in our simulations, the neutron star crust is likely very strong and can support mountains large enough so that their gTavitational wave radiation could limit the spin periods of some stars and might be detectable in large scale interferometers. Furthermore, our microscopic modeling of neutron star crust material can help analyze mechanisms relevant in Magnetar Giant and Micro Flares.

  15. Dialysis Culture of T-Strain Mycoplasmas

    PubMed Central

    Masover, Gerald K.; Hayflick, Leonard

    1974-01-01

    Using dialyzing cultures of T-strain mycoplasmas, it was possible to make some observations relevant to the growth and metabolism of these organisms which would not be possible in nondialyzing cultures due to growth inhibition of the organisms by elevated pH and increased ammonium ion concentration in media containing urea. The rate of ammonia accumulation was found to be related to the initial urea concentration in the medium and could not be accounted for by any change in the multiplication rate of the organisms. More ammonia was generated than could be accounted for by the added urea alone, suggesting that an ammonia-producing activity other than urease may be present in T-strain mycoplasmas. Titers above 107 color change units per ml were achieved in dialysis cultures of a T-strain mycoplasma in the presence of urea, and such titers were maintained for approximately 60 h during dialysis culture in the absence of added urea. PMID:4595203

  16. Apparent-Strain Correction for Combined Thermal and Mechanical Testing

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; O'Neil, Teresa L.

    2007-01-01

    Combined thermal and mechanical testing requires that the total strain be corrected for the coefficient of thermal expansion mismatch between the strain gage and the specimen or apparent strain when the temperature varies while a mechanical load is being applied. Collecting data for an apparent strain test becomes problematic as the specimen size increases. If the test specimen cannot be placed in a variable temperature test chamber to generate apparent strain data with no mechanical loads, coupons can be used to generate the required data. The coupons, however, must have the same strain gage type, coefficient of thermal expansion, and constraints as the specimen to be useful. Obtaining apparent-strain data at temperatures lower than -320 F is challenging due to the difficulty to maintain steady-state and uniform temperatures on a given specimen. Equations to correct for apparent strain in a real-time fashion and data from apparent-strain tests for composite and metallic specimens over a temperature range from -450 F to +250 F are presented in this paper. Three approaches to extrapolate apparent-strain data from -320 F to -430 F are presented and compared to the measured apparent-strain data. The first two approaches use a subset of the apparent-strain curves between -320 F and 100 F to extrapolate to -430 F, while the third approach extrapolates the apparent-strain curve over the temperature range of -320 F to +250 F to -430 F. The first two approaches are superior to the third approach but the use of either of the first two approaches is contingent upon the degree of non-linearity of the apparent-strain curve.

  17. Stochastic disease extinction in multistrain diseases with interacting strains

    NASA Astrophysics Data System (ADS)

    Bianco, Simone; Shaw, Leah; Schwartz, Ira

    2009-03-01

    The study of multistrain diseases, diseases with several coexisting strains, is a major challenge for mathematical biology. Examples of such diseases are influenza, HIV, dengue and ebola. In this work we present an agent-based model for multistrain diseases with strain interactions mediated by antibody-dependent enhancement. An individual infected with a strain develops antibodies which will protect him/her against all the strains. When the level of protection wanes, the presence of antibodies will enhance the infectiousness of the individual when an infection with a different strain occurs. This mechanism is called antibody-dependent enhancement (ADE). We use this model to investigate the role that fluctuations due to system size have on disease extinction paths and discuss how interactions mediated by ADE affect rates of disease fade-out. Finally, we discuss the effect that varying the number of strains has on disease extinction.

  18. Biaxial compressive strain engineering in graphene/boron nitride heterostructures.

    PubMed

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

    2012-01-01

    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. PMID:23189242

  19. Strain engineering of diamond silicon vacancy centers in MEMS cantilevers

    NASA Astrophysics Data System (ADS)

    Meesala, Srujan; Sohn, Young-Ik; Atikian, Haig; Holzgrafe, Jeffrey; Zhang, Mian; Burek, Michael; Loncar, Marko

    2016-05-01

    The silicon vacancy (SiV) center in diamond has recently attracted attention as a solid state quantum emitter due to its attractive optical properties. We fabricate diamond MEMS cantilevers, and use electrostatic actuation to apply controlled strain fields to single SiV centers implanted in these devices. The strain response of the four electronic transitions of the SiV at 737 nm is measured via cryogenic (4 K) photoluminescence excitation. We demonstrate over 300 GHz of tuning for the mean transition frequency between the ground and excited states, and over 100 GHz of tuning for the orbital splittings within the ground and excited states. The interaction Hamiltonian for strain fields is inferred, and large strain susceptibilities of the order 1 PHz/strain are measured. We discuss prospects to utilize our device to reduce phonon-induced decoherence in SiV spin qubits, and to exploit the large strain susceptibilities for hybrid quantum systems based on nanomechanical resonators.

  20. In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri

    PubMed Central

    Porro, Laura B.; Ross, Callum F.; Iriarte-Diaz, Jose; O'Reilly, James C.; Evans, Susan E.; Fagan, Michael J.

    2014-01-01

    In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology. PMID:24577443

  1. The strained state cosmology

    NASA Astrophysics Data System (ADS)

    Tartaglia, Angelo

    2016-01-01

    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity 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 reproduces 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 theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  2. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  3. Accurate strain measurements in highly strained Ge microbridges

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Osvaldo Dias, G.; Pauc, N.; Duchemin, I.; Rouchon, D.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Niquet, Y.-M.; Geiger, R.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2016-06-01

    Ge under high strain is predicted to become a direct bandgap semiconductor. Very large deformations can be introduced using microbridge devices. However, at the microscale, strain values are commonly deduced from Raman spectroscopy using empirical linear models only established up to ɛ100 = 1.2% for uniaxial stress. In this work, we calibrate the Raman-strain relation at higher strain using synchrotron based microdiffraction. The Ge microbridges show unprecedented high tensile strain up to 4.9% corresponding to an unexpected Δω = 9.9 cm-1 Raman shift. We demonstrate experimentally and theoretically that the Raman strain relation is not linear and we provide a more accurate expression.

  4. Network of flexible capacitive strain gauges for the reconstruction of surface strain

    NASA Astrophysics Data System (ADS)

    Wu, Jingzhe; Song, Chunhui; Saleem, Hussam S.; Downey, Austin; Laflamme, Simon

    2015-05-01

    Monitoring of surface strain on mesosurfaces is a difficult task, often impeded by the lack of scalability of conventional sensing systems. A solution is to deploy large networks of flexible strain gauges, a type of large area electronics. The authors have recently proposed a soft elastomeric capacitor (SEC) as an economical skin-type solution for large-scale deployment onto mesosurfaces. The sensing principle is based on a measurable change in the sensor’s capacitance upon strain. In this paper, we study the performance of the sensor at reconstructing surface strain map and deflection shapes. A particular feature of the sensor is that it measures surface strain additively, because it is not utilized within a Wheatstone bridge configuration. An algorithm is proposed to decompose the additive in-plane strain measurements from the SEC into principal components. The algorithm consists of assuming a polynomial shape function, and deriving the strain based on Kirchhoff plate theory. A least-squares estimator (LSE) is used to minimize the error between the assumed model and the SEC signals after the enforcement of boundary conditions. Numerical simulations are conducted on a symmetric rectangular cantilever thin plate under symmetric and asymmetric static loads to demonstrate the accuracy and real-time applicability of the algorithm. The performance of the algorithm is further examined on an asymmetric cantilever laminated thin plate constituted with orthotropic materials mimicking a wind turbine blade, and subjected to a non-stationary wind load. Results from simulations show good performance of the algorithm at reconstructing the surface strain maps for both in-plane principal strain components, and that it can be applied in real time. However, its performance can be improved by strengthening assumptions on boundary conditions. The algorithm exhibits robustness in performance with respect to load and noise in signals, except when most of the sensors’ signals are

  5. [Acetobutylic fermentation: strains and regional raw materials].

    PubMed

    Benassi, F O; Bloos, R K; de Rambaldo, L A

    1983-01-01

    The purpose of the present work was to show, as a first stage, that it is possible to characterize autochtohnous strains of Clostridium acetobutilicum of a good solvent producing capacity, specially N-butanol, through the utilization of suitable techniques for isolating anaerobic microorganisms. Cassava roots were employed as raw material using suitable culture media and an anaerobic jar of cold catalyst. The fermentative capacity of the strains thus isolated was evaluated against a control strain of Clostridium acetobutilicum. Even though some of the strains showed a greater solvent producing power, most of them showed lower fermentation capacity than the control strain, which could be increased, by applying successive thermic treatments. As a second stage, and due to the low cost production of cassava in the Province of Misiones, we studied its utilization as an acetone-butanol fermentation substrate. Mashes composed of binary mixtures of cassava flour and variable amounts of integral flour maize or soy were treated with selected "starters" of Clostridium acetobutilicum, being further processed according to standardized techniques in order to obtain the already mentioned solvents. Mashes concentration influence was also studied using culture media the composition of which proved to be excellent in all experiments carried out under "static system" conditions. The highest fermentative yields (maximum value recorded: 26,20 g of total solvents, with respect to dry solids), were recorded for mashes obtained from mixtures containing integral maize flour; these showed a higher degree of nutrients utilization than those prepared with integral soy flour. PMID:6400763

  6. Crack initiation under generalized plane strain conditions

    SciTech Connect

    Shum, D.K.M.; Merkle, J.G.

    1991-01-01

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab.

  7. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  8. On Boreholes and PBO Borehole Strain

    NASA Astrophysics Data System (ADS)

    Gladwin, M. T.; Mee, M. W.

    2003-12-01

    Borehole tensor strainmeters (GTSM) installed in Australia and California have established a baseline of data spanning more than twenty years. The current baseline of data allows characterisation of a moderate number of instruments in a range of very different environments in a way which defines reasonable performance expectations for the upcoming PBO deployments. A generic understanding of effects which result from the process of installation of the instrument in a stressed rock mass emerges. This indicates that, provided due allowance is made for experimentally determined borehole recovery effects, the contribution of borehole strain meters more than adequately fills the observational gap between high stability/long term geodetic measurements of strain and strain rates and high resolution/high frequency seismic observations of earth deformation processes. The various strain relief processes associated with the installation procedures and borehole recovery effects associated with pre-existing stress fields will be documented. Procedures for calibration of the total borehole inclusion and for progressive removal of effects due to rock anisotropy and visco-elastic creep of the grout and rock close to the borehole from far field tectonic effects will be defined and illustrated with examples. Observed deviations from these processes will be shown to be small and consistent with otherwise observed or implied fault motions. Full details of these borehole induced processes are, however, difficult to determine in the early years following installation, particularly if there is significant tectonic activity at the time. Once quantified for each site, the effects can be robustly removed from data streams.

  9. The meaning of role strain.

    PubMed

    Ward, C R

    1986-01-01

    Explicating the meaning of the concept of role strain is important in role theory formulation, an area requiring further development to provide explanations and predictions for both patient and provider roles. In this analysis, the use of the term role strain is traced from the structural-functionalist and symbolic-interactionist perspectives. Descriptive, stipulative, and connotative definitions of role strain are derived, and necessary and relevant properties are proposed. Antecedent and intervening conditions for role strain are outlined from the literature. Role strain manifestations and empirical referents are presented, and an initial step is taken toward a theoretical formulation by defining role strain within the context of role stress. PMID:3079985

  10. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGESBeta

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  11. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  12. Carbon fiber-ZnO nanowire hybrid structures for flexible and adaptable strain sensors

    NASA Astrophysics Data System (ADS)

    Liao, Qingliang; Mohr, Markus; Zhang, Xiaohui; Zhang, Zheng; Zhang, Yue; Fecht, Hans-Jörg

    2013-11-01

    We report the flexible piezotronic strain sensors fabricated using carbon fiber-ZnO nanowire hybrid structures by a novel and reliable method. The I-V characteristic of the sensor shows high sensitivity to external strain due to the change in Schottky barrier height (SBH), which has a linear relationship with strain. This fabricated strain sensor has a quick, real-time current response under both static and dynamic mechanical loads. The change in SBH resulted from the strain-induced piezoelectric potential is investigated by band gap theory. In this work we develop a new feasible method to fabricate a flexible strain sensor within the fabric adapted to textile structures, able to measure their strain.We report the flexible piezotronic strain sensors fabricated using carbon fiber-ZnO nanowire hybrid structures by a novel and reliable method. The I-V characteristic of the sensor shows high sensitivity to external strain due to the change in Schottky barrier height (SBH), which has a linear relationship with strain. This fabricated strain sensor has a quick, real-time current response under both static and dynamic mechanical loads. The change in SBH resulted from the strain-induced piezoelectric potential is investigated by band gap theory. In this work we develop a new feasible method to fabricate a flexible strain sensor within the fabric adapted to textile structures, able to measure their strain. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03536k

  13. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  14. Novel strained superjunction VDMOS

    NASA Astrophysics Data System (ADS)

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.

    2015-09-01

    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  15. Strain Release Amination

    PubMed Central

    Gianatassio, Ryan; Lopchuk, Justin M.; Wang, Jie; Pan, Chung-Mao; Malins, Lara R.; Prieto, Liher; Brandt, Thomas A.; Collins, Michael R.; Gallego, Gary M.; Sach, Neal W.; Spangler, Jillian E.; Zhu, Huichin; Zhu, Jinjiang; Baran, Phil S.

    2015-01-01

    To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C–C and C–N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late-stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation. PMID:26816372

  16. Ultrasonic actuators: Remote strain measurements, high strain horns and ultrasonic chromatography

    NASA Astrophysics Data System (ADS)

    Lee, Chung Hoon

    In this thesis, optical diffraction strain measurement, silicon-based ultrasonic horn actuators for thin film testing, and mufluidic assay systems are presented. Optical ultrasonic strain measurement: Using optical diffraction gratings integrated on a PZT/silicon laminate actuator, the strain on the actuator was optically and remotely measured. The methodology, limitations, analytical and numerical (ANSYS) analysis are presented. This technology of diffraction grating for ultrasonic strain measurements could lead to an instrument useful for remote monitoring of strain on MEMS sensors. Design of high efficiency silicon-based ultrasonic horn, and their fabrication for thin film testing under cyclic load: A detailed ultrasonic horn design and its analysis are resented. For this application a Gaussian horn is utilized. Most ultrasonic horns have a single point maximum strain point along the horn resulting in strain gradient at all points. For the purpose of straining thin films it is desirable to have areas of spatially constant strain fields. Remarkably, the Gaussian horn has a constant strain area suitable for thin film testing. High strain values can lead to testing not only fatigue, but also fracture of thin films. We feel that the ability to generate constant ultrasonic strain areas on silicon is a technique suitable for industrial and academic material characterization. A portable high-intensity ultrasonic actuator for mufluidic separation (ultrasonic chromatography): Micro-particle manipulation in a liquid using ultrasonic fields in a micro-channel, principle of operation, and analysis are presented. Beads of different sizes could be separated within an optically viewable aperture (˜100 mum). It is found that the separation occurs due to ultrasonic radiation force and a new inertial force, acting on the beads. The key mechanism of focusing beads at the nodes of ultrasonic standing waves, and the origin of the inertial force for the separation are described. The

  17. Prolonged cyclic strain inhibits human endothelial cell growth.

    PubMed

    Peyton, Kelly J; Liu, Xiao-ming; Durante, William

    2016-01-01

    The vascular endothelium is continuously exposed to cyclic mechanical strain due to the periodic change in vessel diameter as a result of pulsatile blood flow. Since emerging evidence indicates the cyclic strain plays an integral role in regulating endothelial cell function, the present study determined whether application of a physiologic regimen of cyclic strain (6% at 1 hertz) influences the proliferation of human arterial endothelial cells. Prolonged exposure of human dermal microvascular or human aortic endothelial cells to cyclic strain for up to 7 days resulted in a marked decrease in cell growth. The strain-mediated anti-proliferative effect was associated with the arrest of endothelial cells in the G2/M phase of the cell cycle, did not involve cell detachment or cytotoxicity, and was due to the induction of p21. Interestingly, the inhibition in endothelial cell growth was independent of the strain regimen since prolonged application of constant or intermittent 6% strain was also able to block endothelial cell proliferation. The ability of chronic physiologic cyclic strain to inhibit endothelial cell growth represents a previously unrecognized mechanism by which hemodynamic forces maintain these cells in a quiescent, non-proliferative state. PMID:26709656

  18. Interfacial residual thermal strain

    NASA Astrophysics Data System (ADS)

    Kasen, M.; Santoyo, R.

    A method has been developed for assessing the influence of polymer chemical composition and of processing parameters on the magnitude of residual stress developed in glass-fibre-reinforced composites subjected to various cure cycles and subsequently cooled to cryogenic temperatures. The test method was applied to nine resin types, including epoxy, vinyl ester, polyester, cyanate ester and phenolic formulations. Results suggest that polyester resin develops substantially less overall residual strain than do the other resin systems.

  19. Ovulation and Due Date Calculator

    MedlinePlus

    ... Mom-to-be tools Ovulation and due date calculator Preconception health quiz Pregnancy know-how quiz Government ... Pregnancy > Pregnancy This information in Spanish ( en español ) Calculator Content last updated September 27, 2010. Resources last ...

  20. Reliable strain measurement in transistor arrays by robust scanning transmission electron microscopy

    SciTech Connect

    Kim, Suhyun; Kim, Joong Jung; Jung, Younheum; Lee, Kyungwoo; Byun, Gwangsun; Hwang, KyoungHwan; Lee, Sunyoung; Lee, Kyupil

    2013-09-15

    Accurate measurement of the strain field in the channels of transistor arrays is critical for strain engineering in modern electronic devices. We applied atomic-resolution high-angle annular dark-field scanning transmission electron microscopy to quantitative measurement of the strain field in transistor arrays. The quantitative strain profile over 20 transistors was obtained with high reliability and a precision of 0.1%. The strain field was found to form homogeneously in the channels of the transistor arrays. Furthermore, strain relaxation due to the thin foil effect was quantitatively investigated for thicknesses of 35 to 275 nm.

  1. Sports Hernia: Misdiagnosed Muscle Strain

    MedlinePlus

    ... Manipulative Treatment Becoming a DO Video Library Misdiagnosed Muscle Strain Can Be A Pain Page Content If ... speeds, sports hernias are frequently confused with common muscle strain ,” says Michael Sampson, DO, who practices in ...

  2. Genealogies of mouse inbred strains.

    PubMed

    Beck, J A; Lloyd, S; Hafezparast, M; Lennon-Pierce, M; Eppig, J T; Festing, M F; Fisher, E M

    2000-01-01

    The mouse is a prime organism of choice for modelling human disease. Over 450 inbred strains of mice have been described, providing a wealth of different genotypes and phenotypes for genetic and other studies. As new strains are generated and others become extinct, it is useful to review periodically what strains are available and how they are related to each other, particularly in the light of available DNA polymorphism data from microsatellite and other markers. We describe the origins and relationships of inbred mouse strains, 90 years after the generation of the first inbred strain. Given the large collection of inbred strains available, and that published information on these strains is incomplete, we propose that all genealogical and genetic data on inbred strains be submitted to a common electronic database to ensure this valuable information resource is preserved and used efficiently. PMID:10615122

  3. Construction of the Inbred Strain.

    PubMed

    Shinya, Minori

    2016-01-01

    Genetically homogeneous populations such as inbred strains are valuable experimental tools in various fields of biomedical analyses. In many animals, inbred strains are established by consecutive sib-pair mating for a minimum of 20 generations. As the generation proceeds, fitness of the population reduces usually. Therefore, in order to establish inbred strains, the important point is the selection of pairs in good condition at each generation. Here, I describe the procedure and tips for generating inbred strains in zebrafish. PMID:27464804

  4. Strain calibration of optical FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  5. Strainrange partitioning - A total strain range version. [for creep fatigue life prediction by summing inelastic and elastic strain-range-life relations for two Ni base superalloys

    NASA Technical Reports Server (NTRS)

    Halford, G. R.; Saltsman, J. F.

    1983-01-01

    Procedures are presented for expressing the Strainrange Partitioning (SRP) method for creep fatigue life prediction in terms of total strain range. Inelastic and elastic strain-range - life relations are summed to give total strain-range - life relations. The life components due to inelastic strains are dealt with using conventional SRP procedures while the life components due to elastic strains are expressed as families of time-dependent terms for each type of SRP cycle. Cyclic constitutive material behavior plays an important role in establishing the elastic strain-range life relations as well as the partitioning of the inelastic strains. To apply the approach, however, it is not necessary to have to determine the magnitude of the inelastic strain range. The total strain SRP approach is evaluated and verified using two nickel base superalloys, AF2-1DA and Rene 95. Excellent agreement is demonstrated between observed and predicted cyclic lifetimes with 70 to 80 percent of the predicted lives falling within factors of two of the observed lives. The total strain-range SRP approach should be of considerable practical value to designers who are faced with creep-fatigue problems for which the inelastic strains cannot be calculated with sufficient accuracy to make reliable life predictions by the conventional inelastic strain range SRP approach.

  6. Structural studies of fungal cell-wall polysaccharides from two strains of Talaromyces flavus.

    PubMed

    Parra, E; Jiménez-Barbero, J; Bernabé, M; Leal, J A; Prieto, A; Gómez-Miranda, B

    1994-01-01

    The water-soluble cell-wall polysaccharides isolated from strains CBS 352.72 and 310.38 of Talaromyces flavus have been investigated by chemical analyses and NMR studies. Two different skeletons coexist, having the structures: [formula:see text]. The small differences between the polysaccharides isolated from both strains are probably due to slight diminution of branching in strain 352.72, as compared with strain 310.38. PMID:8149378

  7. Marble decay due to microcracking

    NASA Astrophysics Data System (ADS)

    Shushakova, V.; Fuller, E. R., Jr.; Heidelbach, F.; Siegesmund, S.

    2012-04-01

    An actual degradation phenomenon of marble structures, i.e., microcracking, is examined via computer simulations with a microstructure-based finite element modelling. Crack initiation and crack propagation were characterized, as well their dependence on grain- shape preferred orientation (SPO), lattice preferred orientation (LPO), grain size and grain-boundary fracture toughness. Calcite is used as an illustrative example. Results are expected to be general for myriad marble microstructures, as the thermophysical properties of various marbles do not differ that much. Three SPOs were analyzed: equiaxed grains; elongated grains and a mixture of equiaxed and elongated grains. Six LPOs were considered: a random orientation distribution function (ODF); an ODF with strong directional crystal texture generated via March Dollase fiber-texture; and four types of actual marble texture as measured on marble samples with electron back-scattered diffraction (EBSD). Two different grain sizes were analyzed: fine grains range up to 200μm and medium size grains of approximate 1mm. The fracture surface energy for the grain boundaries was chosen to be 20 % and 40 % of the fracture surface energy of a grain, so that both intergranular and transgranular fractures were possible. Simulations were performed for both heating and cooling by 50 °C in steps of 1 °C. Microcracking results were correlated with the thermoelastic responses (indicators) related to degradation. Certain combinations of SPO, LPO, grain size, and grain-boundary fracture toughness have a significant influence on the thermal-elastic response of marble. For instance, thermal stresses and elastic strain energy are a strong function of the LPO. With increasing LPO the strain energy density and the maximum principal stress decreases. With decreasing grain size and increasing LPO and SPO, the area of microcracking is smaller and microcracking commences at a higher temperature differential.

  8. Genotypic comparison of Pantoea agglomerans plant and clinical strains

    PubMed Central

    2009-01-01

    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. agglomerans clinical reports

  9. The relationship between strain geometry and geometrically necessary dislocations

    NASA Astrophysics Data System (ADS)

    Hansen, Lars; Wallis, David

    2016-04-01

    The kinematics of past deformations are often a primary goal in structural analyses of strained rocks. Details of the strain geometry, in particular, can help distinguish hypotheses about large-scale tectonic phenomena. Microstructural indicators of strain geometry have been heavily utilized to investigate large-scale kinematics. However, many of the existing techniques require structures for which the initial morphology is known, and those structures must undergo the same deformation as imposed macroscopically. Many deformed rocks do not exhibit such convenient features, and therefore the strain geometry is often difficult (if not impossible) to ascertain. Alternatively, crystallographic textures contain information about the strain geometry, but the influence of strain geometry can be difficult to separate from other environmental factors that might affect slip system activity and therefore the textural evolution. Here we explore the ability for geometrically necessary dislocations to record information about the deformation geometry. It is well known that crystallographic slip due to the motion of dislocations yields macroscopic plastic strain, and the mathematics are established to relate dislocation glide on multiple slip systems to the strain tensor of a crystal. This theoretical description generally assumes that dislocations propagate across the entire crystal. However, at any point during the deformation, dislocations are present that have not fully transected the crystal, existing either as free dislocations or as dislocations organized into substructures like subgrain boundaries. These dislocations can remain in the lattice after deformation if the crystal is quenched sufficiently fast, and we hypothesize that this residual dislocation population can be linked to the plastic strain geometry in a quantitative manner. To test this hypothesis, we use high-resolution electron backscatter diffraction to measure lattice curvatures in experimentally deformed

  10. Prosthetic Valve Endocarditis and Bloodstream Infection Due to Mycobacterium chimaera

    PubMed Central

    Achermann, Yvonne; Rössle, Matthias; Hoffmann, Matthias; Deggim, Vanessa; Kuster, Stefan; Zimmermann, Dieter R.; Hombach, Michael; Hasse, Barbara

    2013-01-01

    Prosthetic valve endocarditis (PVE) due to fast-growing nontuberculous mycobacteria (NTM) has been reported anecdotally. Reports of PVE with slowly growing NTM, however, are lacking. We present here one case of PVE and one case of bloodstream infection caused by Mycobacterium chimaera. Randomly amplified polymorphic DNA (RAPD)-PCR indicated a relatedness of the two M. chimaera strains. Both patients had heart surgery 2 years apart from each other. A nosocomial link was not detected. PMID:23536407

  11. Large anisotropic deformation of skyrmions in strained crystal.

    PubMed

    Shibata, K; Iwasaki, J; Kanazawa, N; Aizawa, S; Tanigaki, T; Shirai, M; Nakajima, T; Kubota, M; Kawasaki, M; Park, H S; Shindo, D; Nagaosa, N; Tokura, Y

    2015-07-01

    Mechanical control of magnetism is an important and promising approach in spintronics. To date, strain control has mostly been demonstrated in ferromagnetic structures by exploiting a change in magnetocrystalline anisotropy. It would be desirable to achieve large strain effects on magnetic nanostructures. Here, using in situ Lorentz transmission electron microscopy, we demonstrate that anisotropic strain as small as 0.3% in a chiral magnet of FeGe induces very large deformations in magnetic skyrmions, as well as distortions of the skyrmion crystal lattice on the order of 20%. Skyrmions are stabilized by the Dzyaloshinskii-Moriya interaction, originating from a chiral crystal structure. Our results show that the change in the modulation of the strength of this interaction is amplified by two orders of magnitude with respect to changes in the crystal lattice due to an applied strain. Our findings may provide a mechanism to achieve strain control of topological magnetic structures based on the Dzyaloshinskii-Moriya interaction. PMID:26030654

  12. Spall Response of Tantalum at Extreme Strain-Rates

    NASA Astrophysics Data System (ADS)

    Hahn, Eric; Germann, Tim; Meyers, Marc

    Strain-rate and microstructure play a significant role in the ultimate mechanical response of materials. Using non-equilibrium molecular dynamics simulations, we characterize the ductile tensile failure of single and nanocrystalline tantalum over multiple orders of magnitude of strain-rate. This comparison is extended to over nine orders of magnitude including experimental results from resent laser shock campaigns. Spall strength primarily follows a power law dependence with strain-rate over this extensive range. In all cases, voids nucleate heterogeneously at pre-existing defects. Predictions based on traditional theory suggest that, as strain-rate increases, tensile strength should increase. Alternatively, as grain size decreases, tensile strength may decrease due to an increased propensity to fail at a growing volume fraction of grain boundaries. Strain-rate and grain size dictate void nucleation sites by changing the type and density of available defects: vacancies, dislocations, twins, and grain boundaries.

  13. Strain relaxation in graphene grown by chemical vapor deposition

    SciTech Connect

    Troppenz, Gerald V. Gluba, Marc A.; Kraft, Marco; Rappich, Jörg; Nickel, Norbert H.

    2013-12-07

    The growth of single layer graphene by chemical vapor deposition on polycrystalline Cu substrates induces large internal biaxial compressive strain due to thermal expansion mismatch. Raman backscattering spectroscopy and atomic force microscopy were used to study the strain relaxation during and after the transfer process from Cu foil to SiO{sub 2}. Interestingly, the growth of graphene results in a pronounced ripple structure on the Cu substrate that is indicative of strain relaxation of about 0.76% during the cooling from the growth temperature. Removing graphene from the Cu substrates and transferring it to SiO{sub 2} results in a shift of the 2D phonon line by 27 cm{sup −1} to lower frequencies. This translates into additional strain relaxation. The influence of the processing steps, used etching solution and solvents on strain, is investigated.

  14. Development of a high temperature static strain sensor

    NASA Astrophysics Data System (ADS)

    Hulse, Charles O.; Bailey, Richard S.; Grant, Howard P.

    1986-10-01

    The goal of this program is to develop an electrical resistance strain gage system which will accurately measure the static strains of superalloy blades and vanes in gas turbine engines running on a test stand. Accurate knowledge of these strains is essential to reaching the goals of the HOST program in the selection and experimental verification of the various theoretical models developed to understand and improve the performance of these engines. The specific objective is to develop a complete system capable of making strain measurements of up to + or - 10 percent of full scale during a 50 hour period at temperatures as high as 1250 K. In addition to survival and stability, attaining a low temperature coefficient of resistance, of the order of 20 ppm/K or less, was a major goal. This requirement arises from the presently unavoidable uncertainties in measurement of the exact temperatures inside gas turbines for use in making corrections for apparent strain due to temperature.

  15. Development of a high temperature static strain sensor

    NASA Technical Reports Server (NTRS)

    Hulse, Charles O.; Bailey, Richard S.; Grant, Howard P.

    1986-01-01

    The goal of this program is to develop an electrical resistance strain gage system which will accurately measure the static strains of superalloy blades and vanes in gas turbine engines running on a test stand. Accurate knowledge of these strains is essential to reaching the goals of the HOST program in the selection and experimental verification of the various theoretical models developed to understand and improve the performance of these engines. The specific objective is to develop a complete system capable of making strain measurements of up to + or - 10 percent of full scale during a 50 hour period at temperatures as high as 1250 K. In addition to survival and stability, attaining a low temperature coefficient of resistance, of the order of 20 ppm/K or less, was a major goal. This requirement arises from the presently unavoidable uncertainties in measurement of the exact temperatures inside gas turbines for use in making corrections for apparent strain due to temperature.

  16. Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors.

    PubMed

    Amjadi, Morteza; Turan, Mehmet; Clementson, Cameron P; Sitti, Metin

    2016-03-01

    There is an increasing demand for flexible, skin-attachable, and wearable strain sensors due to their various potential applications. However, achieving strain sensors with both high sensitivity and high stretchability is still a grand challenge. Here, we propose highly sensitive and stretchable strain sensors based on the reversible microcrack formation in composite thin films. Controllable parallel microcracks are generated in graphite thin films coated on elastomer films. Sensors made of graphite thin films with short microcracks possess high gauge factors (maximum value of 522.6) and stretchability (ε ≥ 50%), whereas sensors with long microcracks show ultrahigh sensitivity (maximum value of 11,344) with limited stretchability (ε ≤ 50%). We demonstrate the high performance strain sensing of our sensors in both small and large strain sensing applications such as human physiological activity recognition, human body large motion capturing, vibration detection, pressure sensing, and soft robotics. PMID:26842553

  17. Strain actuated aeroelastic control

    NASA Technical Reports Server (NTRS)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  18. [Echinococcus and strain concepts].

    PubMed

    Utük, Armağan Erdem; Simsek, Sami

    2008-01-01

    Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Echinococcus granulosus includes a number of genetic variants and, up to date, analyses of mitochondrial DNA sequences have identified ten distinct genetic types (genotypes G1-10). This categorization follows closely the pattern of strain variation emerging based on biological characteristics. The extensive variation in E. granulosus may influence life-cycle patterns, host specificity, development rate, antigenicity, transmission dynamics, sensitivity to chemotherapeutic agents, and pathology. In this review, the recent genetic characterizations of Echinococcus genus have been summarized. PMID:18351549

  19. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  20. Characterization of oriented cracks with differential strain analysis

    NASA Technical Reports Server (NTRS)

    Siegfried, R.; Simmons, G.

    1978-01-01

    Linear strain of a rock sample as a function of hydrostatic pressure can be measured with a precision of 2 millionths. Such high-precision data for three orthogonal directions allow calculation of the distribution function for the porosity due to cracks' closing completely at a given pressure. Such data for at least six independent directions yield the zero-pressure strain tensor due to cracks' closing completely at a given pressure. The principal values and axes of this tensor distribution function provide information about the orientation of cracks as a function of closure pressure. The mathematical basis for the technique is developed, and the technique is illustrated with differential strain data for two samples, the Westerly (Rhode Island) granite and the Twin Sisters (Washington) dunite. Strain-tensor calculations reveal that each of these samples has a different type of anisotropic crack distribution.

  1. Due Process Hearing Case Study

    ERIC Educational Resources Information Center

    Bateman, David F.

    2008-01-01

    Ben is a 16-year-old student who resides with his family in an unnamed School District. He is eligible for special education by reason of specific learning disability and ADHD. His parents requested a due process hearing, alleging that the District failed to provide him with a free appropriate public education (FAPE) and requesting reimbursement…

  2. Economic losses due to catastrophes

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-04-01

    Worldwide economic loss due to catastrophic events added up to US140 billion in 2013, with insured losses adding up to 45 billion, according to a report by the insurance provider Swiss Re. Though these numbers are down from 196 billion in economic losses and 81 billion in insurance losses in 2012, Swiss Re reports an upward trend in losses.

  3. Due Process Hearing Case Study

    ERIC Educational Resources Information Center

    Bateman, David F.; Jones, Marni Gail

    2010-01-01

    This article presents a due process hearing case study of a mother who contended that his son, D.J., has been denied of a free and appropriate public education (FAPE) of his School District after being suspended from school. D.J., an elementary student, had been described as hyperactive, inattentive, defiant, and often volatile. He was identified…

  4. Strain Analysis of the de Mattia Test

    NASA Astrophysics Data System (ADS)

    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.

  5. Quality Control On Strained Semiconductor Devices

    SciTech Connect

    Dommann, Alex; Neels, Antonia

    2010-11-24

    New semiconductor devices are based very often on strained silicon which promises to squeeze more device performance out of current devices. With strained silicon it is possible to get the same device performance using less power. The technique is using strain as a 'design element' for silicon to improve the device performance and has become a hot topic in semiconductor research in the past years. However in the same time topics like 'System in Package'(SiP) on thin wafers are getting more and more important. The chips of thin wafers in advanced packaging are extremely sensitive to induced stresses due to packaging issues. If we are using now strain as a design element for improving device performance we increase the sensitivity again and therefore also the risk of aging of such SiP's. High Resolution X-ray diffraction (HRXRD) techniques such as Rocking Curves (RC's) and Reciprocal Space Mapping (RSM) are therefore very powerful tools to study the stresses in packaged devices.

  6. High strain-rate magnetoelasticity in Galfenol

    NASA Astrophysics Data System (ADS)

    Domann, J. P.; Loeffler, C. M.; Martin, B. E.; Carman, G. P.

    2015-09-01

    This paper presents the experimental measurements of a highly magnetoelastic material (Galfenol) under impact loading. A Split-Hopkinson Pressure Bar was used to generate compressive stress up to 275 MPa at strain rates of either 20/s or 33/s while measuring the stress-strain response and change in magnetic flux density due to magnetoelastic coupling. The average Young's modulus (44.85 GPa) was invariant to strain rate, with instantaneous stiffness ranging from 25 to 55 GPa. A lumped parameters model simulated the measured pickup coil voltages in response to an applied stress pulse. Fitting the model to the experimental data provided the average piezomagnetic coefficient and relative permeability as functions of field strength. The model suggests magnetoelastic coupling is primarily insensitive to strain rates as high as 33/s. Additionally, the lumped parameters model was used to investigate magnetoelastic transducers as potential pulsed power sources. Results show that Galfenol can generate large quantities of instantaneous power (80 MW/m3 ), comparable to explosively driven ferromagnetic pulse generators (500 MW/m3 ). However, this process is much more efficient and can be cyclically carried out in the linear elastic range of the material, in stark contrast with explosively driven pulsed power generators.

  7. Finite Element Analysis of Brain Injury due to Head Impact

    NASA Astrophysics Data System (ADS)

    Suh, Chang Min; Kim, Sung Ho; Goldsmith, Werner

    Traumatic Brain Injury (TBI) due to head impact by external impactor was analyzed using Finite Element Method (FEM). Two-dimensiona modeling was performed according to Magnetic Resonance Imaging (MRI) data of Mongolian subject. Pressure variation in a cranium due to external impact was analyzed in order to simulate Nahum et al.'s cadaver test.6 And, analyzed results were compared with Nahum et al.'s experimental data.6 As results, stress and strain behaviors of the brain during impact were accorded with experimental data qualitatively even though there were some differences in quantitative values. In addition, they were accorded with other references about brain injury as well.

  8. Multiple Rescue Factors Within a Wolbachia Strain

    PubMed Central

    Zabalou, Sofia; Apostolaki, Angeliki; Pattas, Savvas; Veneti, Zoe; Paraskevopoulos, Charalampos; Livadaras, Ioannis; Markakis, George; Brissac, Terry; Merçot, Hervé; Bourtzis, Kostas

    2008-01-01

    Wolbachia-induced cytoplasmic incompatibility (CI) is expressed when infected males are crossed with either uninfected females or females infected with Wolbachia of different CI specificity. In diploid insects, CI results in embryonic mortality, apparently due to the the loss of the paternal set of chromosomes, usually during the first mitotic division. The molecular basis of CI has not been determined yet; however, several lines of evidence suggest that Wolbachia exhibits two distinct sex-dependent functions: in males, Wolbachia somehow “imprints” the paternal chromosomes during spermatogenesis (mod function), whereas in females, the presence of the same Wolbachia strain(s) is able to restore embryonic viability (resc function). On the basis of the ability of Wolbachia to induce the modification and/or rescue functions in a given host, each bacterial strain can be classified as belonging in one of the four following categories: mod+ resc+, mod− resc+, mod− resc−, and mod+ resc−. A so-called “suicide” mod+ resc− strain has not been found in nature yet. Here, a combination of embryonic cytoplasmic injections and introgression experiments was used to transfer nine evolutionary, distantly related Wolbachia strains (wYak, wTei, wSan, wRi, wMel, wHa, wAu, wNo, and wMa) into the same host background, that of Drosophila simulans (STCP strain), a highly permissive host for CI expression. We initially characterized the modification and rescue properties of the Wolbachia strains wYak, wTei, and wSan, naturally present in the yakuba complex, upon their transfer into D. simulans. Confocal microscopy and multilocus sequencing typing (MLST) analysis were also employed for the evaluation of the CI properties. We also tested the compatibility relationships of wYak, wTei, and wSan with all other Wolbachia infections. So far, the cytoplasmic incompatibility properties of different Wolbachia variants are explained assuming a single pair of modification and rescue

  9. Strain mapping on gold thin film buckling and siliconblistering

    SciTech Connect

    Goudeau, P.; Tamura, N.; Parry, G.; Colin, J.; Coupeau, C.; Cleymand, F.; Padmore, H.

    2005-09-01

    Stress/Strain fields associated with thin film buckling induced by compressive stresses or blistering due to the presence of gas bubbles underneath single crystal surfaces are difficult to measure owing to the microscale dimensions of these structures. In this work, we show that micro Scanning X-ray diffraction is a well suited technique for mapping the strain/stress tensor of these damaged structures.

  10. Thermal conductivity of graphene mediated by strain and size

    DOE PAGESBeta

    Kuang, Youdi; Shi, Sanqiang; Wang, Xinjiang; Huang, Baoling; Lindsay, Lucas

    2016-06-09

    Based on first-principles calculations and full iterative solution of the linearized Boltzmann–Peierls transport equation for phonons, we systematically investigate effects of strain, size and temperature on the thermal conductivity k of suspended graphene. The calculated size-dependent and temperature-dependent k for finite samples agree well with experimental data. The results show that, contrast to the convergent room-temperature k = 5450 W/m-K of unstrained graphene at a sample size ~8 cm, k of strained graphene diverges with increasing the sample size even at high temperature. Out-of-plane acoustic phonons are responsible for the significant size effect in unstrained and strained graphene due tomore » their ultralong mean free path and acoustic phonons with wavelength smaller than 10 nm contribute 80% to the intrinsic room temperature k of unstrained graphene. Tensile strain hardens the flexural modes and increases their lifetimes, causing interesting dependence of k on sample size and strain due to the competition between boundary scattering and intrinsic phonon–phonon scattering. k of graphene can be tuned within a large range by strain for the size larger than 500 μm. These findings shed light on the nature of thermal transport in two-dimensional materials and may guide predicting and engineering k of graphene by varying strain and size.« less

  11. Active and structural strain model for magnetostrictive transducers

    NASA Astrophysics Data System (ADS)

    Dapino, Marcelo J.; Smith, Ralph C.; Flatau, Alison B.

    1998-07-01

    We consider the modeling of strains generated by magnetostrictive materials in response to applied magnetic fields. The active or external component of the strain is due to the rotation of magnetic moments within the material to align with the applied field. This is characterized through consideration of the Jiles-Atherton mean field theory for ferromagnetic hysteresis in combination with a quadratic moment rotation model for magnetostriction. The second component of the strain reflects the passive or internal dynamics of the rod as it vibrates. This is modeled through force balancing which yields a wave equation with magnetostrictive inputs. The validity of a combined transducer model is illustrated through comparison with experimental data.

  12. Strain hardening of metal parts with use of impulse wave

    NASA Astrophysics Data System (ADS)

    Kirichek, A. V.; Soloviev, D. L.

    2016-04-01

    This work describes a strain hardening method with the use of impulse waves. This method increases energy transfer to the strained material extending its technological capabilities with development of a deep strengthened layer and allowing formation of a heterogeneous hardened structure using plastic deformation. This structure has specified distribution of the hard and soft (visco-plastic) areas. Due to development of the heterogeneous structure in the surface layer created by strain hardening with impulse wave, durability of parts that suffer contact fatigue loading is significantly increased.

  13. Geodetic strain measurements in Washington.

    USGS Publications Warehouse

    Savage, J.C.; Lisowski, M.; Prescott, W.H.

    1981-01-01

    Two new geodetic measurements of strain accumulation in the state of Washington for the interval 1972-1979 are reported. Near Seattle the average principal strain rates are 0.07 + or - 0.03 mu strain/yr N19oW and -0.13 + or - 0.02 mu strain/yr N71oE, and near Richland (south central Washington) the average principal strain rates are -0.02 + or - 0.01 mu strain/yr N36oW and -0.04 + or - 0.01 mu strain/yr N54oE. Extension is taken as positive, and the uncertainties quoted are standard deviations. A measurement of shear strain accumulation (dilation not determined) in the epoch 1914- 1966 along the north coast of Vancouver Island by the Geodetic Survey of Canada indicates a marginally significant accumulation of right-lateral shear (0.06 + or - 0.03 mu rad/yr) across the plate boundary (N40oW strike). Although there are significant differences in detail, these strain measurements are roughly consistent with a crude dislocation model that represents subduction of the Juan de Fuca plate. The observed accumulation of strain implies that large, shallow, thrust earthquakes should be expected off the coast of Washington and British Columbia. However, this conclusion is not easily reconciled with either observations of elevation change along the Washington coast or the focal mechanism solutions for shallow earthquakes in Washington. -Authors

  14. Subsidence due to geothermal fluid withdrawal

    SciTech Connect

    Narasimhan, T.N.; Goyal, K.P.

    1982-10-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the U.S. and elsewhere. Vertical ground displacements of upto 4.5 m and horizontal ground displacements of up t o 0.5 m have been observed at Wairakei, New Zealand that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy and Cerro Prieto, Mexico. Observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant therma mechanisms. Although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  15. Subsidence due to geothermal fluid withdrawal

    SciTech Connect

    Narasimhan, T. N.; Goyal, K. P.

    1984-12-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the United States, and elsewhere. Vertical ground displacements of up to 4.5 m and horizontal ground displacements of up to 0.5 m have been observed at Wairakei, New Zealand, that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy, and Cerro Prieto, Mexico. In this paper, observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence, and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant thermal mechanisms. Finally, although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  16. Severe hypercalcemia due to teriparatide

    PubMed Central

    Karatoprak, Cumali; Kayatas, Kadir; Kilicaslan, Hanifi; Yolbas, Servet; Yazimci, Nurhan Aliye; Gümüskemer, Tolga; Demirtunç, Refik

    2012-01-01

    Osteoporosis that is by far the most common metabolic bone disease, has been defined as a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. Anabolic therapy with teriparatide, recombinant human parathyroid hormone (PTH 1-34), stimulates bone formation and resorption and improves trabecular and cortical microarchitecture. Teriparatide is indicated for the treatment of men and postmenopausal women with osteoporosis who are at high risk for fracture, including those who have failed or are intolerant of previous osteoporosis therapy. In conclusion, although teriparatide seems quite effective in the treatment of osteoporosis, it may cause life-threatening hypercalcemia. Therefore, patients should be closely monitored if symptoms of hypercalcemia are present during teriparatide treatment. Sustained hypercalcemia due to teriparatide treatment can not be seen in literature so we wanted to emphasize that severe hypercalcemia may develop due to teriperatide. PMID:22529492

  17. Parotitis due to anaerobic bacteria.

    PubMed

    Matlow, A; Korentager, R; Keystone, E; Bohnen, J

    1988-01-01

    Although Staphylococcus aureus remains the pathogen most commonly implicated in acute suppurative parotitis, the pathogenic role of gram-negative facultative anaerobic bacteria and strict anaerobic organisms in this disease is becoming increasingly recognized. This report describes a case of parotitis due to Bacteroides disiens in an elderly woman with Sjögren's syndrome. Literature reports on seven additional cases of suppurative parotitis due to anaerobic bacteria are reviewed. Initial therapy of acute suppurative parotitis should include coverage for S. aureus and, in a very ill patient, coverage of gram-negative facultative organisms with antibiotics such as cloxacillin and an aminoglycoside. A failure to respond clinically to such a regimen or isolation of anaerobic bacteria should lead to the consideration of the addition of clindamycin or penicillin. PMID:3287567

  18. Oxytocin and the oxytocin receptor underlie intra-strain, but not inter-strain, social recognition

    PubMed Central

    Macbeth, Abbe H.; Lee, Heon-Jin; Edds, Jennifer; Young, W. Scott

    2009-01-01

    We studied three lines of oxytocin (Oxt) and oxytocin receptor (Oxtr) knockout (KO) male mice (Oxt−/−, total Oxtr−/−, and partial-forebrain Oxtr (OxtrFB/FB)) with established deficits in social recognition to further refine our understanding of their deficits with regard to stimulus female's strain. We used a modified social discrimination paradigm in which subjects are singly housed only for the duration of the test. Additionally, stimulus females are singly-housed throughout testing and are presented within corrals for rapid comparison of investigation by subject males. Wildtype (WT) males from all three lines discriminated between familiar and novel females of three different strains (C57BL/6, Balb/c, Swiss-Webster). No KO males discriminated between familiar and novel Balb/c or C57BL/6 females. Male Oxt−/− and Oxtr−/− mice, but not OxtrFB/FB mice, discriminated between familiar and novel Swiss-Webster females. As this might indicate a global deficit in individual recognition for OxtrFB/FB males, we examined their ability to discriminate between females from different strains and compared performance with Oxtr−/− males. WT and KO males from both lines were able to distinguish between familiar and novel females from different strains, indicating the social recognition deficit is not universal. Instead, we hypothesize that the Oxtr is involved in “fine” intra-strain recognition, but is less important in “broad” inter-strain recognition. We also present the novel finding of decreased investigation across tests, which is likely an artifact of repeated testing and not due to stimulus female's strain or age of subject males. PMID:19531157

  19. Ventriculitis due to Cryptococcus uniguttulatus.

    PubMed

    McCurdy, L H; Morrow, J D

    2001-01-01

    Infections due to non-neoformans cryptococci are rare. We report the first case of a human infection caused by Cryptococcus uniguttulatus. Ventriculitis caused by this organism developed in a 65-year-old woman who had had repair of an internal carotid aneurysm. In vitro sensitivity testing showed the Cryptococcus species sensitive to amphotericin B and itraconazole. Treatment with amphotericin led to resolution of the infection. PMID:11213945

  20. Printing of stretchable silk membranes for strain measurements.

    PubMed

    Ling, Shengjie; Zhang, Qiang; Kaplan, David L; Omenetto, Fiorenzo; Buehler, Markus J; Qin, Zhao

    2016-07-01

    Quantifying the deformation of biological tissues under mechanical loading is crucial to understand its biomechanical response in physiological conditions and important for designing materials and treatments for biomedical applications. However, strain measurements for biological tissues subjected to large deformations and humid environments are challenging for conventional methods due to several limitations such as strain range, boundary conditions, surface bonding and biocompatibility. Here we propose the use of silk solutions and printing to synthesize prototype strain gauges for large strain measurements in biological tissues. The study shows that silk-based strain gauges can be stretched up to 1300% without failure, which is more than two orders of magnitude larger than conventional strain gauges, and the mechanics can be tuned by adjusting ion content. We demonstrate that the printing approach can accurately provide well bonded fluorescent features on the silk membranes using designs which can accurately measure strain in the membrane. The results show that these new strain gauges measure large deformations in the materials by eliminating the effects of sliding from the boundaries, making the measurements more accurate than direct outputs from tensile machines. PMID:27241909

  1. Two-strain competition in quasineutral stochastic disease dynamics.

    PubMed

    Kogan, Oleg; Khasin, Michael; Meerson, Baruch; Schneider, David; Myers, Christopher R

    2014-10-01

    We develop a perturbation method for studying quasineutral competition in a broad class of stochastic competition models and apply it to the analysis of fixation of competing strains in two epidemic models. The first model is a two-strain generalization of the stochastic susceptible-infected-susceptible (SIS) model. Here we extend previous results due to Parsons and Quince [Theor. Popul. Biol. 72, 468 (2007)], Parsons et al. [Theor. Popul. Biol. 74, 302 (2008)], and Lin, Kim, and Doering [J. Stat. Phys. 148, 646 (2012)]. The second model, a two-strain generalization of the stochastic susceptible-infected-recovered (SIR) model with population turnover, has not been studied previously. In each of the two models, when the basic reproduction numbers of the two strains are identical, a system with an infinite population size approaches a point on the deterministic coexistence line (CL): a straight line of fixed points in the phase space of subpopulation sizes. Shot noise drives one of the strain populations to fixation, and the other to extinction, on a time scale proportional to the total population size. Our perturbation method explicitly tracks the dynamics of the probability distribution of the subpopulations in the vicinity of the CL. We argue that, whereas the slow strain has a competitive advantage for mathematically "typical" initial conditions, it is the fast strain that is more likely to win in the important situation when a few infectives of both strains are introduced into a susceptible population. PMID:25375480

  2. Influence of Lysobacter enzymogenes Strain C3 on Nematodes

    PubMed Central

    Chen, J.; Moore, W. H.; Yuen, G. Y.; Kobayashi, D.; Caswell-Chen, E. P.

    2006-01-01

    Chitinolytic microflora may contribute to biological control of plant-parasitic nematodes by causing decreased egg viability through degradation of egg shells. Here, the influence of Lysobacter enzymogenes strain C3 on Caenorhabditis elegans, Heterodera schachtii, Meloidogyne javanica, Pratylenchus penetrans, and Aphelenchoides fragariae is described. Exposure of C. elegans to L. enzymogenes strain C3 on agar resulted in almost complete elimination of egg production and death of 94% of hatched juveniles after 2 d. Hatch of H. schachtii eggs was about 50% on a lawn of L. enzymogenes strain C3 on agar as compared to 80% on a lawn of E. coli. Juveniles that hatched on a lawn of L. enzymogenes strain C3 on agar died due to disintegration of the cuticle and body contents. Meloidogyne javanica juveniles died after 4 d exposure to a 7-d-old chitin broth culture of L. enzymogenes strain C3. Immersion of A. fragariae, M. javanica, and P. penetrans juveniles and adults in a nutrient broth culture of L. enzymogenes strain C3 led to rapid death and disintegration of the nematodes. Upon exposure to L. enzymogenes strain C3 cultures in nutrient broth, H. schachtii juveniles were rapidly immobilized and then lysed after three days. The death and disintegration of the tested nematodes suggests that toxins and enzymes produced by this strain are active against a range of nematode species. PMID:19259452

  3. Strains at the myotendinous junction predicted by a micromechanical model

    PubMed Central

    Sharafi, Bahar; Ames, Elizabeth G.; Holmes, Jeffrey W.; Blemker, Silvia S.

    2011-01-01

    The goal of this work was to create a finite element micromechanical model of the myotendinous junction (MTJ) to examine how the structure and mechanics of the MTJ affect the local micro-scale strains experienced by muscle fibers. We validated the model through comparisons with histological longitudinal sections of muscles fixed in slack and stretched positions. The model predicted deformations of the A-bands within the fiber near the MTJ that were similar to those measured from the histological sections. We then used the model to predict the dependence of local fiber strains on activation and the mechanical properties of the endomysium. The model predicted that peak micro-scale strains increase with activation and as the compliance of the endomysium decreases. Analysis of the models revealed that, in passive stretch, local fiber strains are governed by the difference of the mechanical properties between the fibers and the endomysium. In active stretch, strain distributions are governed by the difference in cross-sectional area along the length of the tapered region of the fiber near the MTJ. The endomysium provides passive resistance that balances the active forces and prevents the tapered region of the fiber from undergoing excessive strain. These model predictions lead to the following hypotheses: (i) the increased likelihood of injury during active lengthening of muscle fibers may be due to the increase in peak strain with activation and (ii) endomysium may play a role in protecting fibers from injury by reducing the strains within the fiber at the MTJ. PMID:21945569

  4. Life cycle structural health monitoring of airframe structures by strain mapping using FBG sensors

    NASA Astrophysics Data System (ADS)

    Takahashi, I.; Sekine, K.; Takeya, H.; Iwahori, Y.; Takeda, N.; Koshioka, Y.

    2010-04-01

    The purpose of this research is to develop the structural health monitoring system for composite airframe structures by strain mapping through their life cycles. We apply FBG sensor networks to CFRP pressure bulkheads and monitor the strain through their life cycles: molding, processing, assembly, operation and maintenance. Damages, defects and deformations which occurred in each stage are detected using the strain distribution. At first, we monitored the strain of CFRP laminates during molding and processing with FBG sensors. As a result, not only the thermal strain on curing process but also strain change due to demolding was measured precisely. In addition, we analyzed the change in strain distribution due to damages of CFRP pressure bulkhead such as stringer debonding and impact damage of skin under operational load in flight. On the basis of these results, the location of FBG sensors suitable for the detection of damages was determined.

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

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2013-08-01

    interest in strain studies as well. Researchers in China investigated the effects of tensile strain on the thermal conductivity of graphene nanoribbons. Tuning the thermal conductivity of nanomaterials is highly desirable to optimize their functionality [5]. Wei and colleagues use computer simulations based on reverse nonequilibrium molecular dynamics (RNEMD) to demonstrate what they describe as 'a strain-induced magic flexibility of thermal engineering for carbon-based nanostructures', which may provide a new approach for tailoring nanomaterial functionality. Despite the attractions of more recently discovered carbon nanomaterials silicon remains the bedrock of the semiconductor device industry. Germanium nanostructures also hold significant interest, such as Ge nanowires, which have high mobility and a conveniently low synthesis temperature [6]. In fact the potential applications of germanium nanowires in field effect transistors and nanobridge devices prompted Jagadish and colleagues in Australia, Korea and the UK to investigate the growth of taper-free kinked Ge nanowires in silicon [7]. As they point out many recent reports have highlighted such kinked nanowires as valuable components for novel nanodevices. The work reported by Hrauda and colleagues in this issue looks at the growth of germanium islands on a silicon substrate rather than nanowires [2]. They grow islands on pre-patterned silicon with different levels of Ge deposition with the aim of better understanding how to manage the effects of strain due to lattice mismatch between the two metals. Their results show that considerably more Ge can be deposited without dislocations forming than previously thought and reveal a distinctive cycle of changing island morphologies as Ge is deposited. They add, 'Strain relaxation is revealed to be the main driving force of a rather complex evolution of island shape and Ge distribution'. In reference to his theory of atoms Bohr is once said to have told Werner Heisenberg

  6. Bicrystals with strain gradient effects

    SciTech Connect

    Shu, J.Y.

    1997-01-09

    Boundary between two perfectly bonded single crystals plays an important role in determining the deformation of the bicrystals. This work addresses the role of the grain boundary by considering the elevated hardening of a slip system due to a slip gradient. The slip gradients are associated with geometrically necessary dislocations and their effects become pronounced when a representative length scale of the deformation field is comparable to the dominant microstructural length scale of a material. A new rate-dependent crystal plasticity theory is presented and has been implemented within the finite element method framework. A planar bicrystal under uniform in-plane loading is studied using the new crystal theory. The strain is found to be continuous but nonuniform within a boundary layer around the interface. The lattice rotation is also nonuniform within the boundary layer. The width of the layer is determined by the misorientation of the grains, the hardening of slip systems, and most importantly by the characteristic material length scales. The overall yield strength of the bicrystal is also obtained. A significant grain-size dependence of the yield strength, the Hall- Petch effect is predicted.

  7. Forming patterns and mechanical properties of austenitic chromium-nickel steel due to strain aging

    NASA Astrophysics Data System (ADS)

    Kamyshanchenko, N. V.; Krasilnikov, V. V.; Nikulin, I. S.; Gal'tsev, A. V.; Belenko, V. A.; Gal'tseva, I. N.

    2016-02-01

    The work presents the results of studies of forming patterns and mechanical properties of martensite transformation, found in the chromium-nickel steels of 08X18H10T grade, subjected to pre-heat treatment followed by deformation aging. Internal energy state is determined by using acoustic emission. The observed patterns improve the mechanical parameters of steels quenched and plastically deformed at low temperature and then subjected to temper under load in the optimum temperature being associated with obtaining a more stable condition of the structure through the processes of relaxation of internal stresses, high dispersion and uniform distribution of carbides and intermetallic particles, increasing the density of dislocations as well as through other processes occurring during deformation aging martensite. Start your abstract here...

  8. Strain Engineering in Graphene

    NASA Astrophysics Data System (ADS)

    Castro Neto, Antonio

    2011-03-01

    Graphene is a unique example of a one atom thick metallic membrane. Hence, graphene brings together properties of soft and hard condensed matter systems. The elementary electronic excitations in graphene, the Dirac quasiparticles, couple in a singular way to structural distortions in the form of scalar and vector potentials. Therefore, graphene has an effective electrodynamics where structural deformations couple to the Dirac particles at equal footing to electric and magnetic fields. This so-called strain engineering of the electronic properties of graphene opens doors for a new paradigm in terms of electronic devices, where electronic properties can be manipulated at will using its membrane-like properties. I thank partial support from from DOE Grant DE-FG02-08ER46512 and ONR Grant MURI N00014-09-1-1063.

  9. Searching for Strain Transients in PBO data

    NASA Astrophysics Data System (ADS)

    Wei, M.; McGuire, J. J.; Richardson, E.; Kraft, R. L.; Hardwig, M. D.

    2011-12-01

    We applied a recently developed strain anomaly detector, the Network Stain Filter [Ohtani et al., 2010], to the continuous GPS datasets from the PBO in Alaska and Salton Trough. The strategy of the filter is to find spatially and temporally coherent signals by processing data from the entire network simultaneously. Compared to previous Network Inversion Filter [Segall and Matthews, 1997], the new detector does not require the knowledge of potential sources, which can be either unknown and/or very numerous in a large tectonically active area. At Alaska, we find a strain anomaly between Kodiak Island and Kenai Peninsula that began in early 2010. There are earthquakes that are likely related to the strain anomaly. The physical interpretation of the strain anomaly is still in progress. The secular motion since 2006 that PBO recorded is consistent with a model that consist of two locked patches on Kodiak Island and Kenai Peninsula and a creeping patch near Cook Inlet as determined earlier by Zweck et al. [2002]. Seasonal signals dominate in the data and are highly correlated between stations in the horizontal components. The reason for this correlation in seasonal term azimuths between stations is not clear. At Salton Trough, the post-seismic deformation of the 2010 Mw 7.2 El Mayor Earthquake dominates the transient signals. The maximum post-seismic slip recorded by the GPS is 23 mm during 1.5 years after the earthquake (Site ID P494). Additionally, we are exploring using InSAR data as a complimentary method for detecting strain anomaly in areas with shallow sources, such as in the Salton Trough. A creep event on the Superstition Hills Fault in October 2006 has been observed by InSAR but missed by nearby GPS stations due to low amplitude at the location [Wei et al., 2009].

  10. Transient hypofibrinogenemia due to allopurinol

    PubMed Central

    Yin, ZhiQiang; Xu, JiaLi; Li, YongQiang; Xia, JiPing; Luo, Dan

    2014-01-01

    This study reports a case of an 80-year-old male who suffered from drug eruption due to oral allopurinol for the treatment of gout. This patient complained of widespread erythema and maculopapule with itch, and small quantities of purplish-red rash with diffused distribution on four limbs were noted. After he was hospitalized, the area with purpuric rash increased in size, and hypofibrinogenemia was found. After treatment with intravenous infusion of fibrinogen and cryoprecipitate, and continued treatment with high-dose methylprednisolone, the skin rash gradually went away. This is the first report of purpura and hypofibrinogenemia induced by allopurinol and the pathophysiology underlying this reaction remained unknown. PMID:25214766

  11. Depressive disorder due to craniopharyngioma.

    PubMed Central

    Spence, S A; Taylor, D G; Hirsch, S R

    1995-01-01

    Secondary causes of depression are legion, and must always be considered in patients presenting with features atypical of primary idiopathic depressive disorder. The case described is that of a middle-aged woman presenting initially with a major depressive disorder who was subsequently found to have a craniopharyngioma, leading to a revised diagnosis of mood disorder due to the tumour. Some features of the presentation might have led to earlier diagnosis had their localizing significance been recognized. Diencephalic lesions should always be considered in patients presenting with the hypersomnic-hyperphagic variant of depressive disorder. Images Figure 1 PMID:8544149

  12. Anaphylaxis Due to Head Injury

    PubMed Central

    Bruner, Heather C.; Bruner, David I.

    2015-01-01

    Both anaphylaxis and head injury are often seen in the emergency department, but they are rarely seen in combination. We present a case of a 30-year-old woman who presented with anaphylaxis with urticaria and angioedema following a minor head injury. The patient responded well to intramuscular epinephrine without further complications or airway compromise. Prior case reports have reported angioedema from hereditary angioedema during dental procedures and maxillofacial surgery, but there have not been any cases of first-time angioedema or anaphylaxis due to head injury. PMID:25987924

  13. Thermal strain imaging: a review

    PubMed Central

    Seo, Chi Hyung; Shi, Yan; Huang, Sheng-Wen; Kim, Kang; O'Donnell, Matthew

    2011-01-01

    Thermal strain imaging (TSI) or temporal strain imaging is an ultrasound application that exploits the temperature dependence of sound speed to create thermal (temporal) strain images. This article provides an overview of the field of TSI for biomedical applications that have appeared in the literature over the past several years. Basic theory in thermal strain is introduced. Two major energy sources appropriate for clinical applications are discussed. Promising biomedical applications are presented throughout the paper, including non-invasive thermometry and tissue characterization. We present some of the limitations and complications of the method. The paper concludes with a discussion of competing technologies. PMID:22866235

  14. Hydrogen production from microbial strains

    DOEpatents

    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.

  15. Strain in silicon nanowire beams

    NASA Astrophysics Data System (ADS)

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre

    2012-12-01

    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  16. Strain variation in corrugated graphene

    NASA Astrophysics Data System (ADS)

    Wang, Xuanye; Tantiwanichapan, Khwanchai; Christopher, Jason; Paiella, Roberto; Swan, Anna

    2015-03-01

    Raman spectroscopy is a powerful non-destructive technique for analyzing strain in graphene. Recently there has been interest in making corrugated graphene devices with varying spatial wavelengths Λ for plasmonic and THz applications. Transferring graphene onto corrugated substrates introduces strain, which if there was perfect clamping (high fraction) would cause a periodic strain variation. However, the strain variation for pattern size smaller than the diffraction limit λ makes it hard to precisely model the strain distribution. Here we present a detailed study on how strain varies in corrugated graphene with sub-diffraction limit periodicity Λ < λ. Mechanically exfoliated graphene was deposited onto sinusoidal shape silicon dioxide gratings with Λ=400 nm period using the pick and place transfer technique. We observed that the graphene is not rigidly clamped, but partially slides to relieve the strain. We model the linewidth variation to extract the local strain variation as well as the sliding in the presence of charge puddling in graphene. The method gives us a better understanding on graphene slippage and strain distribution in graphene on a corrugated substrate with sub-diffraction limit spatial period.

  17. A Practical Data Recovery Technique for Long-Term Strain Monitoring of Mega Columns during Construction

    PubMed Central

    Choi, Se Woon; Kwon, EunMi; Kim, Yousok; Hong, Kappyo; Park, Hyo Seon

    2013-01-01

    A practical data recovery method is proposed for the strain data lost during the safety monitoring of mega columns. The analytical relations among the measured strains are derived to recover the data lost due to unexpected errors in long-term measurement during construction. The proposed technique is applied to recovery of axial strain data of a mega column in an irregular building structure during construction. The axial strain monitoring using the wireless strain sensing system was carried out for one year and five months between 23 July 2010 and 22 February 2012. During the long-term strain sensing, three different types of measurement errors occurred. Using the recovery technique, the strain data that could not be measured at different intervals in the measurement were successfully recovered. It is confirmed that the problems that may occur during long-term wireless strain sensing of mega columns during construction could be resolved through the proposed recovery method. PMID:23966189

  18. Strain mapping with parts-per-million resolution in synthetic type-Ib diamond plates

    SciTech Connect

    Macrander, Albert T.; Krasnicki, Szczesny; Zhong Yuncheng; Maj, Josef; Chu, Yong S.

    2005-11-07

    A general method to map strain with parts per million (ppm) resolution in single-crystal wafers and plates is demonstrated. An x-ray technique has been used to obtain separate maps of strain and tilt across synthetic diamond growth sectors. Data consisting of rocking curve maps obtained with a charge coupled device detector were analyzed. The strain results image the growth sectors and reveal a strain pileup near the sector boundaries. The diamond was yellow to the eye due to nitrogen impurities. Not only the topography of the strain map, but also the strain magnitudes, are consistent with the strain arising from nitrogen impurities. High strain resolution in the ppm range is needed to observe these effects.

  19. Strain Dependence of Photoluminescense of Individual Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel N.; Leeuw, Tonya K.; Tsyboulski, Dmitri A.; Bachilo, Sergei M.; Weisman, Bruce; Arepalli, Sivaram

    2007-01-01

    We have investigated strain dependence of photoluminescense (PL) spectra of single wall carbon nanotubes (SWNT). Nanotubes were sparsely dispersed in a thin PMMA film applied to acrylic bar, and strained in both compression and extension by bending this bar in either direction in a homebuilt four-point bending rig. The average surface strain was measured with high accuracy by a resistive strain gage applied on top of the film. The near infrared imaging and spectroscopy were performed on the inverted microscope equipped with high numerical aperture reflective objective lens and InGaAs CCD cameras. PL was excited with a diode laser at either 658, 730 or 785 nm, linearly polarized in the direction of the strain. We were able to measure (n,m) types and orientation of individual nanotubes with respect to strain direction and strain dependence of their PL maxima. It was found that PL peak shifts with respect to the values measured in SDS micelles are a sum of three components. First, a small environmental shift due to difference in the dielectric constant of the surrounding media, that is constant and independent of the nanotube type. Second, shift due to isotropic compression of the film during drying. Third, shifts produced by the uniaxial loading of the film in the experiment. Second and third shifts follow expression based on the first-order expansion of the TB hamiltonian. Their magnitude is proportional to the nanotube chiral angle and strain, and direction is determined by the nanotube quantum number. PL strain dependence measured for a number of various nanotube types allows to estimate TB carbon-carbon transfer integral.

  20. Decoherence due to Scattering Atoms

    NASA Astrophysics Data System (ADS)

    Uys, Hermann; Perreault, John; Cronin, Alex

    2004-05-01

    Coherent manipulation of a quantum system is difficult because of uncontrolled interactions with the system's environment. The study of decoherence so introduced is important for progress in quantum mechanical engineering, and for understanding the transition from quantum to classical behavior. We have observed loss of fringe contrast in a Mach-Zhender atom interferometer due to scattering background gas atoms and propose that this might be interpreted as quantum decoherence. Progress will be reported on the use of a general model of decoherence incorporating a semi-classical picture of atom scattering to explain the contrast loss [1]. A formal analogy is made to decoherence due to scattering photons from atoms in an interferometer [2]. [1] S.M. Tan, D.F. Waals, ``Loss of coherence in interferometry", Phys. Rev. A 47 p.4663 (1993) [2] D.A. Kokorowski, A.D. Cronin, T.D. Roberts, and D.E. Pritchard, ``From single- to multiple-photon decoherence in an atom interferometer", Phys. Rev. Lett. 86 p. 2191 (2001)

  1. The effects of academic and interpersonal stress on dating violence among college students: a test of classical strain theory.

    PubMed

    Mason, Brandon; Smithey, Martha

    2012-03-01

    This study examines Merton's Classical Strain Theory (1938) as a causative factor in intimate partner violence among college students. We theorize that college students experience general life strain and cumulative strain as they pursue the goal of a college degree. We test this strain on the likelihood of using intimate partner violence. Strain due to unrealistic expectations of intimate partnership and economic strain are also examined. The analysis examines the following causative factors representing strain: 1) the College Undergraduate Stress Scale (Renner & Mackin, 1998); 2) cumulative academic strain measured by college classification; 3) cumulative intimate partner strain measured as the length of time in the relationship; 4) academic strain measured by number of hours studied weekly, and 5) economic strain measured by number of hours worked weekly. Additionally, we examine the extent to which gender and race/ethnicity differentially affect intimate partner in the context of these measures of strain. The Conflict Tactics Scales II (Straus et al, 1996) are used to measure dating violence and include indicators for sexual coercion, physical aggression, injury, and psychological aggression. Data were collected from 142 students in lower-division classes from Texas Tech University. Results show that general strain and cumulative intimate partner strain increase the use of dating violence among college students. The longer dating partners are in a relationship, the higher the chances of psychological aggression, physical assault, and sexual coercion. Converse to our expectations, time spent working reduces psychological aggression due to reducing time spent together rather than reflecting economic strain. PMID:21987517

  2. Measured strain in Nb3Sn coils during excitation and quence

    SciTech Connect

    Caspi, S.; Barlett, S.E.; Dietderich, D. R.; Ferracin, P.; Gourlay, S. A.; Hannaford, C. R.; Hafalia, A.R.; Lietzke, A.F.; Mattafirri, S.; Nyman, M.; Sabbi, G.

    2005-06-01

    The strain in a high field Nb{sub 3}Sn coil was measured during magnet assembly, cool-down, excitation and spot heater quenches. Strain was measured with a full bridge strain gauge mounted directly over the turns and impregnated with the coil. Two such coils were placed in a 'common coil' fashion capable of reaching 11 T at 4.2 K. The measured steady state strain in the coil is compared with results obtained using the FEM code ANSYS. During quenches, the transient strain (due to temperature rise) was also measured and compared with the calculated mechanical time response to a quench.

  3. Micro-strain sensing using wrinkled stiff thin films on soft substrates as tunable optical grating.

    PubMed

    Ma, Teng; Liang, Hanshuang; Chen, George; Poon, Benny; Jiang, Hanqing; Yu, Hongbin

    2013-05-20

    We report a strain sensing approach that utilizes wrinkled patterns on poly (dimethylsiloxane) (PDMS) as an optical grating to measure thermally-induced strain of different materials. The mechanism for the strain sensing and the effect of PDMS grating on strain sensing are discussed. By bonding the PDMS grating onto a copper or silicon substrate, the coefficient of thermal expansion (CTE) of the substrates can be deduced by measuring the diffraction angle change due to the change in PDMS grating periodicity when thermal strain is introduced. The measured CTEs agree well with the known reference values. PMID:23736421

  4. Highly Stretchable Strain Sensors Using an Electrospun Polyurethane Nanofiber/Graphene Composite.

    PubMed

    Hu, Daqing; Wang, Qinghe; Yu, Jixian; Hao, Wentao; Lu, Hongbo; Zhang, Guobing; Wang, Xianghua; Qiu, Longzhen

    2016-06-01

    A highly flexible and stretchable strain sensor has been prepared by coating chemical reduction of graphene oxide on electrospun polyurethane nanofiber mats. The sensor exhibits an ohmic behavior regardless of applied strains and the current monotonically increases with the increase of the tensile strain. The morphology and stability of electrospun polyurethane nanocomposite mats were also studied. The flexible and stretchable strain sensor has great potential for practical application such as efficient human-motion detection. This cheap and simple process of graphene layer provides an effective fabrication for graphene stretchable electronic devices and strain sensors due to excellent stability and electrical proper. PMID:27427641

  5. Self-affine nature of the stress-strain behavior of thin fiber networks

    NASA Astrophysics Data System (ADS)

    Balankin, Alexander S.; Susarrey, Orlando; Bravo, Armando

    2001-12-01

    The stress-strain behavior of toilet paper is studied. We find that the damaged parts of stress-strain curves possess a self-affine scaling invariance. Moreover, we find that the stress-strain behavior and the rupture line roughness are characterized by the same scaling (Hurst) exponent H, which is not universal: rather it changes from sample to sample. The variations on H are mainly due to fluctuations in the paper structure, which are larger than statistical errors within a sample. Furthermore, the same exponent governs the changes in the stress-strain curve as the strain rate increases. The fractal damage model is employed to explain experimental observations.

  6. Collisional Aggregation Due to Turbulence

    NASA Astrophysics Data System (ADS)

    Pumir, Alain; Wilkinson, Michael

    2016-03-01

    Collisions between particles suspended in a fluid play an important role in many physical processes. As an example, collisions of microscopic water droplets in clouds are a necessary step in the production of macroscopic raindrops. Collisions of dust grains are also conjectured to be important for planet formation in the gas surrounding young stars and to play a role in the dynamics of sand storms. In these processes, collisions are favored by fast turbulent motions. Here we review recent advances in the understanding of collisional aggregation due to turbulence. We discuss the role of fractal clustering of particles and caustic singularities of their velocities. We also discuss limitations of the Smoluchowski equation for modeling such processes. These advances lead to a semiquantitative understanding on the influence of turbulence on collision rates and point to deficiencies in the current understanding of rainfall and planet formation.

  7. Methaemoglobinaemia due to mephedrone ('snow').

    PubMed

    Ahmed, Noor; Hoy, Brent Philip Sew; McInerney, J

    2010-01-01

    Acquired methaemoglobinaemia is a serious complication caused by many oxidising drugs. It presents as cyanosis unresponsive to oxygen therapy. The case of 33-year-old male patient who presented in our department after noticing blue lips and fingers is presented. He had sniffed 1 g of 'snow' after buying it from a head shop. His oxygen saturation by pulse oximeter on room air at presentation was 90%, which did not improve with supplemental oxygen. Arterial blood gas analyses showed partial pressure of oxygen 37 kPa while on supplemental oxygen and a methaemoglobin concentration greater than 25%. The patient denied using any other recreational drugs and was not on regular treatment. Therefore, a diagnosis of methaemoglobinaemia due to mephedrone, which is the active ingredient of 'snow', was made. Treatment is with intravenous methylene blue. Our patient started to improve so methylene blue was not used and he was discharged after 8 h. PMID:22791577

  8. Occupational injuries due to violence.

    PubMed

    Hales, T; Seligman, P J; Newman, S C; Timbrook, C L

    1988-06-01

    Each year in the United States, an estimated 800 to 1,400 people are murdered at work, and an unknown number of nonfatal injuries due to workplace violence occur. Based on Ohio's workers' compensation claims from 1983 through 1985, police officers, gasoline service station employees, employees of the real estate industry, and hotel/motel employees were found to be at the highest risk for occupational violent crime (OVC) injury and death. Grocery store employees, specifically those working in convenience food stores, and employees of the real estate industry had the most reported rapes. Four previously unidentified industries at increased risk of employee victimization were described. Identification of industries and occupations at high risk for crime victimization provides the opportunity to focus preventive strategies to promote employee safety and security in the workplace. PMID:3392614

  9. Inductance due to spin current

    SciTech Connect

    Chen, Wei

    2014-03-21

    The inductance of spintronic devices that transport charge neutral spin currents is discussed. It is known that in a media that contains charge neutral spins, a time-varying electric field induces a spin current. We show that since the spin current itself produces an electric field, this implies existence of inductance and electromotive force when the spin current changes with time. The relations between the electromotive force and the corresponding flux, which is a vector calculated by the cross product of electric field and the trajectory of the device, are clarified. The relativistic origin generally renders an extremely small inductance, which indicates the advantage of spin current in building low inductance devices. The same argument also explains the inductance due to electric dipole current and applies to physical dipoles consist of polarized bound charges.

  10. Single fatherhood due to cancer.

    PubMed

    Yopp, Justin M; Rosenstein, Donald L

    2012-12-01

    Cancer is a leading cause of widowed fatherhood in the USA. Fathers whose spouses have died from cancer constitute a potentially vulnerable population as they adjust to their role as sole or primary caregiver while managing their own grief and that of their children. The importance of addressing the psychological needs of widowed fathers is underscored by data showing that father's coping and emotional availability are closely tied to their bereaved children's mental health. Surprisingly, scant attention has been given to the phenomenon of widowed fatherhood with virtually no clinical resources or research studies devoted to fathers who have lost their wives to cancer. This commentary highlights key challenges facing this underserved population of widowers and calls for development of research agendas and clinical interventions for single fathers due to cancer. PMID:21830258

  11. Spontaneous Pneumoperitoneum due to Constipation

    PubMed Central

    Yamana, Ippei; Noritomi, Tomoaki; Takeno, Shinsuke; Tatsuya, Hashimoto; Sato, Keisuke; Shimaoka, Hideki; Yamaguchi, Ryosuke; Ishii, Fumiaki; Yamada, Teppei; Yamashita, Yuichi

    2015-01-01

    We report a rare case of spontaneous pneumoperitoneum. An 82-year-old Japanese male patient was referred to our hospital because of constipation and abdominal pain. Abdominal computed tomography revealed a large amount of feces in the colon and rectum, and free air in the abdomen. Based on these findings, the patient was diagnosed with gastrointestinal perforation. Emergency exploratory laparotomy was performed. Neither perforation nor ischemic changes were recognized in the digestive tract. The patient's defecation was managed postoperatively until discharge on the 13th postoperative day. The authors assumed that free air, which was released after a mucosal injury due to the internal pressure caused by the presence of a large amount of feces in the colon and rectum, had penetrated the bowel wall through the bowel mucosa. We herein report the present case while also reviewing the pertinent literature. PMID:26676063

  12. Effect of Coating on the Strain Transfer of Optical Fiber Sensors

    PubMed Central

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2011-01-01

    Optical fiber strain sensors with light weight, small dimensions and immunity to electromagnetic interference are widely used in structural health monitoring devices. As a sensor, it is expected that the strains between the optical fiber and host structure are the same. However, due to the shear deformation of the protective coating, the optical fiber strain is different from that of host structure. To improve the measurement accuracy, the strain measured by the optical fiber needs to be modified to reflect the influence of the coating. In this investigation, a theoretical model of the strain transferred from the host material to the optical fiber is developed to evaluate the interaction between the host material and coating. The theoretical predictions are validated with a numerical analysis using the finite element method. Experimental tests are performed to reveal the differential strains between the optical fiber strain sensor and test specimen. The Mach-Zehnder interferometric type fiber-optic sensor is adopted to measure the strain. Experimental results show that the strain measured at the optical fiber is lower than the true strain in the test specimen. The percentage of strain in the test specimen actually transferred to the optical fiber is dependent on the bonded length of the optical fiber and the protective coating. The general trend of the strain transformation obtained from both experimental tests and theoretical predictions shows that the longer the bonded length and the stiffer the coating the more strain is transferred to the optical fiber. PMID:22163993

  13. A method for determination of equine hoof strain patterns using photoelasticity: an in vitro study.

    PubMed

    Dejardin, L M; Arnoczky, S P; Cloud, G L

    1999-05-01

    During impact, equine hooves undergo viscoelastic deformations which may result in potentially harmful strains. Previous hoof strain studies using strain gauges have been inconclusive due to arbitrary gauge placement. Photoelastic stress analysis (PSA) is a full-field technique which visually displays strains over entire loaded surfaces. This in vitro study identifies normal hoof strain patterns using PSA. Custom-made photoelastic plastic sheets were applied to the hoof surface. The hooves were axially loaded (225 kg) under level and varus/valgus conditions. Strain patterns were video-recorded through a polariscope. Strains were concentrated between middle and distal thirds of the hoof wall regardless of the loading conditions. This strain distribution appears to result from the differential expansion of the hoof wall under load. Increasing load resulted in higher strains and asymmetric loading resulted in an ipsilateral increase in strain magnitudes without altering strain locations. This study shows that PSA is a reliable method with which to evaluate hoof strains in vitro and is sensitive enough to reflect subtle load-related strain alterations. PMID:10402137

  14. Inbreeding Ratio and Genetic Relationships among Strains of the Western Clawed Frog, Xenopus tropicalis

    PubMed Central

    Igawa, Takeshi; Watanabe, Ai; Suzuki, Atsushi; Kashiwagi, Akihiko; Kashiwagi, Keiko; Noble, Anna; Guille, Matt; Simpson, David E.; Horb, Marko E.; Fujii, Tamotsu; Sumida, Masayuki

    2015-01-01

    The Western clawed frog, Xenopus tropicalis, is a highly promising model amphibian, especially in developmental and physiological research, and as a tool for understanding disease. It was originally found in the West African rainforest belt, and was introduced to the research community in the 1990s. The major strains thus far known include the Nigerian and Ivory Coast strains. However, due to its short history as an experimental animal, the genetic relationship among the various strains has not yet been clarified, and establishment of inbred strains has not yet been achieved. Since 2003 the Institute for Amphibian Biology (IAB), Hiroshima University has maintained stocks of multiple X. tropicalis strains and conducted consecutive breeding as part of the National BioResource Project. In the present study we investigated the inbreeding ratio and genetic relationship of four inbred strains at IAB, as well as stocks from other institutions, using highly polymorphic microsatellite markers and mitochondrial haplotypes. Our results show successive reduction of heterozygosity in the genome of the IAB inbred strains. The Ivory Coast strains clearly differed from the Nigerian strains genetically, and three subgroups were identified within both the Nigerian and Ivory Coast strains. It is noteworthy that the Ivory Coast strains have an evolutionary divergent genetic background. Our results serve as a guide for the most effective use of X. tropicalis strains, and the long-term maintenance of multiple strains will contribute to further research efforts. PMID:26222540

  15. Inbreeding Ratio and Genetic Relationships among Strains of the Western Clawed Frog, Xenopus tropicalis.

    PubMed

    Igawa, Takeshi; Watanabe, Ai; Suzuki, Atsushi; Kashiwagi, Akihiko; Kashiwagi, Keiko; Noble, Anna; Guille, Matt; Simpson, David E; Horb, Marko E; Fujii, Tamotsu; Sumida, Masayuki

    2015-01-01

    The Western clawed frog, Xenopus tropicalis, is a highly promising model amphibian, especially in developmental and physiological research, and as a tool for understanding disease. It was originally found in the West African rainforest belt, and was introduced to the research community in the 1990s. The major strains thus far known include the Nigerian and Ivory Coast strains. However, due to its short history as an experimental animal, the genetic relationship among the various strains has not yet been clarified, and establishment of inbred strains has not yet been achieved. Since 2003 the Institute for Amphibian Biology (IAB), Hiroshima University has maintained stocks of multiple X. tropicalis strains and conducted consecutive breeding as part of the National BioResource Project. In the present study we investigated the inbreeding ratio and genetic relationship of four inbred strains at IAB, as well as stocks from other institutions, using highly polymorphic microsatellite markers and mitochondrial haplotypes. Our results show successive reduction of heterozygosity in the genome of the IAB inbred strains. The Ivory Coast strains clearly differed from the Nigerian strains genetically, and three subgroups were identified within both the Nigerian and Ivory Coast strains. It is noteworthy that the Ivory Coast strains have an evolutionary divergent genetic background. Our results serve as a guide for the most effective use of X. tropicalis strains, and the long-term maintenance of multiple strains will contribute to further research efforts. PMID:26222540

  16. Complete Genome Sequence of Lactobacillus plantarum Strain B21, a Bacteriocin-Producing Strain Isolated from Vietnamese Fermented Sausage Nem Chua.

    PubMed

    Golneshin, Aida; Adetutu, Eric; Ball, Andrew S; May, Bee K; Van, Thi Thu Hao; Smith, Andrew T

    2015-01-01

    Lactobacillus plantarum strain B21 was isolated from Vietnamese sausage (nem chua) and demonstrated broad antimicrobial activity due to the production of bacteriocins. Here, we report the complete genome sequence of this strain (3,284,260 bp). PMID:25838470

  17. Emerging Enteropathogenic Escherichia coli Strains?

    PubMed Central

    Irino, Kinue; Girão, Dennys M.; Girão, Valéria B.C.; Guth, Beatriz E.C.; Vaz, Tânia M.I.; Moreira, Fabiana C.; Chinarelli, Silvia H.; Vieira, Mônica A.M.

    2004-01-01

    Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic. PMID:15504277

  18. Hypothetical strain-free oligoradicals

    PubMed Central

    Hoffmann, Roald; Eisenstein, Odile; Balaban, Alexandru T.

    1980-01-01

    Several new classes of oligoradicals free of angle strain are suggested and examined by means of molecular orbital calculations. The collapse products of these hypothetical radicals are highly strained molecules. Various electronic strategies for the stabilization of these oligoradicals have been explored. PMID:16592882

  19. Difference Between Strain and Sprain.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Provided in this description of the differences between a strain (damage to the muscle or tendon) and a sprain (damage to the ligament) are definitions of mild, moderate, and severe (first, second, and third degree) strains and sprains. A final caution is given that these are two separate and distinct problems and should be treated as such. (DC)

  20. [Repetition Strain Injury

    PubMed

    Ribeiro

    1997-01-01

    Muscular-skeletal disorders of the upper limbs resulting from work involving repetition strain (RSI) are now the most frequent work-related diseases in early or late industrialized countries. The author maintains that in addition to being work-related diseases, RSIs are symbolic illnesses revealing the contradictions and social pathogenesis of the new cycle of development and crisis in capitalist production. Discussing the social and historical dimensions of this process, the author insists that the low efficacy of technical interventions by labor engineering, ergonomics, and clinical medicine in the prevention, early and adequate diagnosis, and treatment of such post-modern illnesses and the difficulty in rehabilitating and reincorporating such workers reflect precisely a broader determination of health and illness, since the appropriation, incorporation, and use of technological innovations and the new forms of work management are defined according to the exclusive interests of capital. Thus, a growing contingent of young workers (mainly females) from different labor categories are losing or under threat of losing their health and work capacity, two essential and closely linked public values. The solution to the SRI issue must be political and collective. PMID:10886940

  1. Porous silicon strain during in situ ultrahigh vacuum thermal annealing

    NASA Astrophysics Data System (ADS)

    Buttard, D.; Dolino, G.; Faivre, C.; Halimaoui, A.; Comin, F.; Formoso, V.; Ortega, L.

    1999-05-01

    In situ synchrotron radiation measurements of porous silicon (PS) strain have been performed during ultrahigh vacuum (UHV) thermal annealing. For a p+ sample, the initial lattice expansion shifts toward a contraction above 270 °C in relation with hydrogen desorption. For a p- sample, the strain variation is similar to that of a p+ one, but with effects five times larger: after hydrogen desorption, the contraction strain is large (>1.5%) and inhomogeneous. In both cases, most of these strains are elastic as an HF etch re-establishes the initial expansion with a narrow diffraction peak. For p+ samples, the lattice constant exhibited a slow variation during subsequent exposure to air due to a slow oxidation of the annealed porous samples. The origin of these strain variations is discussed in relation with the presence of hydrogen or oxide coverage. The observation of similar variations in other PS properties is also discussed. Finally, the absence of a strain effect during the introduction of water vapor in UHV is discussed as possibly due to a contamination of the PS sample by residual water during the long time passed under UHV at high temperature.

  2. Strain rate sensitivity of nanoindentation creep in an AlCoCrFeNi high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Jiao, Z. M.; Wang, Z. H.; Wu, R. F.; Qiao, J. W.

    2016-09-01

    Creep behaviors of an AlCoCrFeNi high-entropy alloy with the body-centered cubic structure were investigated by nanoindentation. The enhanced strain gradient induced by higher strain rate leads to decreased strain rate sensitivity during creep process. The present alloy exhibits excellent creep resistance, mainly due to its large entropy of mixing and highly distorted lattice structure.

  3. Inelastic Strain Analysis of Solder Joint in NASA Fatigue Specimen

    NASA Technical Reports Server (NTRS)

    Dasgupta, Abhijit; Oyan, Chen

    1991-01-01

    The solder fatigue specimen designed by NASA-GSFC/UNISYS is analyzed in order to obtain the inelastic strain history during two different representative temperature cycles specified by UNISYS. In previous reports (dated July 25, 1990, and November 15, 1990), results were presented of the elastic-plastic and creep analysis for delta T = 31 C cycle, respectively. Subsequent results obtained during the current phase, from viscoplastic finite element analysis of the solder fatigue specimen for delta T = 113 C cycle are summarized. Some common information is repeated for self-completeness. Large-deformation continuum formulations in conjunction with a standard linear solid model is utilized for modeling the solder constitutive creep-plasticity behavior. Relevant material properties are obtained from the literature. Strain amplitudes, mean strains, and residual strains (as well as stresses) accumulated due to a representative complete temperature cycle are obtained as a result of this analysis. The partitioning between elastic strains, time-independent inelastic (plastic) strains, and time-dependent inelastic (creep) strains is also explicitly obtained for two representative cycles. Detailed plots are presented for two representative temperature cycles. This information forms an important input for fatigue damage models, when predicting the fatigue life of solder joints under thermal cycling

  4. Reversible uniaxial strain tuning in atomically thin WSe2

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert; Niehues, Iris; Schneider, Robert; Drüppel, Matthias; Deilmann, Thorsten; Rohlfing, Michael; Michaelis de Vasconcellos, Steffen; Castellanos-Gomez, Andres; Bratschitsch, Rudolf

    2016-06-01

    Due to their unique band structure, single layers of transition metal dichalcogenides are promising for new atomic-scale physics and devices. It has been shown that the band structure and the excitonic transitions can be tuned by straining the material. Recently, the discovery of single-photon emission from localized excitons has put monolayer WSe2 in the spotlight. The localized light emitters might be related to local strain potentials in the monolayer. Here, we measure strain-dependent energy shifts for the A, B, C, and D excitons for uniaxial tensile strain up to 1.4% in monolayer WSe2 by performing absorption measurements. A gauge factor of -54\\tfrac{{{meV}}}{ % }, -50\\tfrac{{{meV}}}{ % }, +17\\tfrac{{{meV}}}{ % }, and -22\\tfrac{{{meV}}}{ % } is derived for the A, B, C, and D exciton, respectively. These values are in good agreement with ab initio GW-BSE calculations. Furthermore, we examine the spatial strain distribution in the WSe2 monolayer at different applied strain levels. We find that the size of the monolayer is crucial for an efficient transfer of strain from the substrate to the monolayer.

  5. Multiple-strain infections of Trypanosoma brucei across Africa.

    PubMed

    Balmer, Oliver; Caccone, Adalgisa

    2008-09-01

    It is becoming increasingly clear that parasitic infections frequently contain multiple strains of the same parasite species. This may have important consequences for the parasite dynamics in the host and thus alter disease and transmission dynamics. In Trypanosoma brucei, the causal agent of human African trypanosomiasis (sleeping sickness), multiple-strain infections have previously been demonstrated to occur. Here, we analyzed field isolates of T. b. gambiense, T. b. rhodesiense, and T. b. brucei, isolated throughout Africa to assess the commonness of multiple-strain infections across the natural range of this parasite. Using eight highly variable microsatellite loci, we found multiple strains in 8.8% of our isolates. Due to the technical challenges of detecting multiple infections this number represents a minimum estimate and the true frequency of multiple-strain infections is likely to be higher. Multiple-strain infections occurred across the entire East-West range of the parasite. Together with previous results, these findings strongly suggest that multiple-strain infections are common for this parasite and that their consequences for epidemiology and parasite evolution should be investigated in detail. PMID:18671933

  6. Strain Discrimination of Staphylococcus aureus Using Superantigen Profiles.

    PubMed

    Tsen, Hau-Yang; Li, Sheng-Chih; Chiang, Yu-Cheng; Tsai, Shuo-Wen

    2016-01-01

    Staphylococcus aureus is one of the major bacterial species that may cause clinical infection and food-poisoning cases. Strains of this species may produce a series of superantigens (SAgs). Due to the importance of staphylococcal infections, reliable methods for the discrimination of strains of this species are important. Such data may allow us to trace the infection origins and be used for epidemiological study. For strain discrimination, genotyping methods, such as pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), and multi-locus sequence typing (MLST), etc., could be used. Recently, toxin gene profiles, which can be used for the elucidation of the genetic and pathogenic relatedness between strains, also have been used to improve the strain discrimination. For S. aureus, as more SAg genes were discovered, the SAg profiles become more useful for the strain discrimination of S. aureus. In this chapter, a method for the discrimination of S. aureus strains using superantigen profiles will be described in detail. PMID:26676035

  7. High-sensitivity strain visualization using electroluminescence technologies

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Jo, Hongki

    2016-04-01

    Visualizing mechanical strain/stress changes is an emerging area in structural health monitoring. Several ways are available for strain change visualization through the color/brightness change of the materials subjected to the mechanical stresses, for example, using mechanoluminescence (ML) materials and mechanoresponsive polymers (MRP). However, these approaches were not effectively applicable for civil engineering system yet, due to insufficient sensitivity to low-level strain of typical civil structures and limitation in measuring both static and dynamic strain. In this study, design and validation for high-sensitivity strain visualization using electroluminescence technologies are presented. A high-sensitivity Wheatstone bridge, of which bridge balance is precisely controllable circuits, is used with a gain-adjustable amplifier. The monochrome electroluminescence (EL) technology is employed to convert both static and dynamic strain change into brightness/color change of the EL materials, through either brightness change mode (BCM) or color alternation mode (CAM). A prototype has been made and calibrated in lab, the linearity between strain and brightness change has been investigated.

  8. Strained graphene Josephson junction with anisotropic d-wave superconductivity

    NASA Astrophysics Data System (ADS)

    Goudarzi, H.; Khezerlou, M.; Kamalipour, H.

    2015-07-01

    Effect of proximity-induced superconductivity in the new two-dimensional structures, as graphene and topological insulator on the Andreev bound states (ABSs) and Josephson supercurrent has attracted much efforts. Motivated by this subject, we study, in particular, the influence of anisotropic Fermi velocity and unconventional d-wave pairing in a strained graphene-based superconductor/normal/ superconductor junction. Strain is applied in the zigzag direction of graphene sheet. In this process, effect of zero energy states and Fermi wavevector mismatch are investigated. It is shown, that strain up to 22% in graphene lattice differently affects Josephson currents in parallel and perpendicular directions of strain. Strain causes to exponentially decrease the supercurrent in the strain direction, whereas increase for other direction. We find that, in one hand, the ABSs strongly depend on strain and, on the other hand, a gap opens in the states with respect to non-zero incidence angle of quasiparticles, where a period of 2 π is obtained for Andreev states. Moreover, we observe no gap for θs ≠ 0 , when the zero energy states (ZESs) occur in α = π / 4 due to anisotropic superconducting gap. In this case, ABSs have a period of 4 π .S

  9. Spherical nanoindentation stress–strain curves

    SciTech Connect

    Pathak, Siddhartha; Kalidindi, Surya R.

    2015-03-24

    Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength in the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.

  10. Spherical nanoindentation stress–strain curves

    DOE PAGESBeta

    Pathak, Siddhartha; Kalidindi, Surya R.

    2015-03-24

    Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength inmore » the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.« less