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Sample records for large strain bulk

  1. Bulk metallic glass composite with good tensile ductility, high strength and large elastic strain limit

    PubMed Central

    Wu, Fu-Fa; Chan, K. C.; Jiang, Song-Shan; Chen, Shun-Hua; Wang, Gang

    2014-01-01

    Bulk metallic glasses exhibit high strength and large elastic strain limit but have no tensile ductility. However, bulk metallic glass composites reinforced by in-situ dendrites possess significantly improved toughness but at the expense of high strength and large elastic strain limit. Here, we report a bulk metallic glass composite with strong strain-hardening capability and large elastic strain limit. It was found that, by plastic predeformation, the bulk metallic glass composite can exhibit both a large elastic strain limit and high strength under tension. These unique elastic mechanical properties are attributed to the reversible B2↔B19′ phase transformation and the plastic-predeformation-induced complicated stress state in the metallic glass matrix and the second phase. These findings are significant for the design and application of bulk metallic glass composites with excellent mechanical properties. PMID:24931632

  2. Bulk Nanolayered Composites: Interfacial Influence on Microstructural Evolution at Large Plastic Strains

    SciTech Connect

    Mara, Nathan A.; Carpenter, John S.; Han, Weizhong; Zheng, Shijian; McCabe, Rodney J.; Wang, Jian; Beyerlein, Irene J.

    2012-07-31

    Conclusions are: (1) As-processed ARB material has similar morphology, chemistry as PVD, but different interfacial structure; (2) Density of interfaces AND interfacial structure play a role in determining hardness, an example is twinning in Cu at the {l_brace}112{r_brace}Cu//{l_brace}112{r_brace}Nb interface and higher strength, no twinning in Cu in the {l_brace}111{r_brace}Cu//{l_brace}110{r_brace}Nb interface; and (3) Need to understand effects of processing history to predict the effects on the interfaces we produce - Amount of strain, Strain Path, Annealing.

  3. Genetic Variation among Staphylococcus aureus Strains from Norwegian Bulk Milk

    PubMed Central

    Jørgensen, H. J.; Mørk, T.; Caugant, D. A.; Kearns, A.; Rørvik, L. M.

    2005-01-01

    Strains of Staphylococcus aureus obtained from bovine (n = 117) and caprine (n = 114) bulk milk were characterized and compared with S. aureus strains from raw-milk products (n = 27), bovine mastitis specimens (n = 9), and human blood cultures (n = 39). All isolates were typed by pulsed-field gel electrophoresis (PFGE). In addition, subsets of isolates were characterized using multilocus sequence typing (MLST), multiplex PCR (m-PCR) for genes encoding nine of the staphylococcal enterotoxins (SE), and the cloverleaf method for penicillin resistance. A variety of genotypes were observed, and greater genetic diversity was found among bovine than caprine bulk milk isolates. Certain genotypes, with a wide geographic distribution, were common to bovine and caprine bulk milk and may represent ruminant-specialized S. aureus. Isolates with genotypes indistinguishable from those of strains from ruminant mastitis were frequently found in bulk milk, and strains with genotypes indistinguishable from those from bulk milk were observed in raw-milk products. This indicates that S. aureus from infected udders may contaminate bulk milk and, subsequently, raw-milk products. Human blood culture isolates were diverse and differed from isolates from other sources. Genotyping by PFGE, MLST, and m-PCR for SE genes largely corresponded. In general, isolates with indistinguishable PFGE banding patterns had the same SE gene profile and isolates with identical SE gene profiles were placed together in PFGE clusters. Phylogenetic analyses agreed with the division of MLST sequence types into clonal complexes, and isolates within the same clonal complex had the same SE gene profile. Furthermore, isolates within PFGE clusters generally belonged to the same clonal complex. PMID:16332822

  4. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    SciTech Connect

    Shvartz, A. Samsonov, A.; Dreiden, G.; Semenova, I.

    2015-10-28

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

  5. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    NASA Astrophysics Data System (ADS)

    Shvartz, A.; Samsonov, A.; Dreiden, G.; Semenova, I.

    2015-10-01

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

  6. On the origin of elastic strain limit of bulk metallic glasses

    SciTech Connect

    Ding, J. Ma, E.; Cheng, Y. Q.

    2014-01-06

    All bulk metallic glasses exhibit a large and almost universal elastic strain limit. Here, we show that the magnitude of the yield strain of the glass state can be quantitatively derived from a characteristic property of the flow state typical in running shear bands (the root cause of yielding). The strain in the shear flow is mostly plastic, but associated with it there is an effective elastic atomic strain. The latter is almost identical for very different model systems in our molecular dynamics simulations, such that the corresponding yield strain is universal at any given homologous temperature.

  7. The bulk piezoresistive characteristics of carbon nanotube composites for strain sensing of structures.

    PubMed

    Kang, Inpil; Joung, Kwan Young; Choi, Gyeong-Rak; Schulz, Mark J; Choi, Yeon-Sun; Hwang, Sung-Ho; Ko, Han Seo

    2007-11-01

    The bulk piezoresistivity of carbon nanotube (CNT) in polymer matrix was discussed to develop a strain sensor for engineering applications. The polymer improves interfacial bonding between the nanotubes and the CNT composite and that enhances the strain transfer, repeatability, and linearity of the sensor. The largest contribution of piezoresistivity of the sensor may come from slippage of overlaying or bundled nanotubes in the matrix, from a macroscopic point of view. Nano interfaces of CNTs in a matrix polymer also contribute to the linear strain response compared to other micro size carbon filler. The strain sensor had a low bandwidth and adequate strain sensitivity. The nanocomposite strain sensor is particularly useful for detecting large strains which can monitor strain and stress on a structure with simple electric circuit for strain monitoring of structures. PMID:18047048

  8. Effect of strain on electronic and thermoelectric properties of few layers to bulk MoS₂.

    PubMed

    Bhattacharyya, Swastibrata; Pandey, Tribhuwan; Singh, Abhishek K

    2014-11-21

    The sensitive dependence of the electronic and thermoelectric properties of MoS₂ on applied strain opens up a variety of applications in the emerging area of straintronics. Using first-principles-based density functional theory calculations, we show that the band gap of a few layers of MoS₂ can be tuned by applying normal compressive (NC) strain, biaxial compressive (BC) strain, and biaxial tensile (BT) strain. A reversible semiconductor-to-metal transition (S-M transition) is observed under all three types of strain. In the case of NC strain, the threshold strain at which the S-M transition occurs increases when the number of layers increase and becomes maximum for the bulk. On the other hand, the threshold strain for the S-M transition in both BC and BT strains decreases when the number of layers increase. The difference in the mechanisms for the S-M transition is explained for different types of applied strain. Furthermore, the effect of both strain type and the number of layers on the transport properties are also studied using Botzmann transport theory. We optimize the transport properties as a function of the number of layers and the applied strain. 3L- and 2L-MoS₂ emerge as the most efficient thermoelectric materials under NC and BT strain, respectively. The calculated thermopower is large and comparable to some of the best thermoelectric materials. A comparison among the feasibility of these three types of strain is also discussed. PMID:25354843

  9. Plasticity in bulk metallic glasses investigated via the strain distribution

    SciTech Connect

    Das, Jayanta; Mattern, Norbert; Eckert, Juergen; Bostroem, Magnus; Kvick, Aake; Yavari, Alain Reza; Greer, Alan Lindsay

    2007-09-01

    We measured the atomic-scale elastic strain in order to investigate the yielding of Zr{sub 55}Cu{sub 20}Ni{sub 10}Al{sub 10}Ti{sub 5} and Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} bulk metallic glasses (BMGs) by x-ray synchrotron radiation at room temperature. High resolution strain scanning reveals a deviation from the linear stress-strain relationship at the onset of macroplastic flow. Similar to polycrystalline metals, a saturation of the elastic strain components has been revealed in the case of the ''plastic'' Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} BMG. The results show that the atomic-level elastic strains of the plastic Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} BMG are more homogeneous compared to the 'brittle' Zr{sub 55}Cu{sub 20}Ni{sub 10}Al{sub 10}Ti{sub 5} glass.

  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. Soft metal constructs for large strain sensor membrane

    NASA Astrophysics Data System (ADS)

    Michaud, Hadrien O.; Teixidor, Joan; Lacour, Stéphanie P.

    2015-03-01

    Thin gold films on silicone display large reversible change in electrical resistance upon stretching. Eutectic liquid metal conductors maintain bulk metal conductivity, even upon extensive elongation. When integrated together, the soft metals enable multidirectional, large strain sensor skin. Their fabrication process combines thermal evaporation of thin gold film patterns through stencil mask with microplotting of eutectic gallium indium microwires, and packaging in silicone rubber. Using three-element rectangular rosettes, we demonstrate a sensor skin that can reliably and locally quantify the plane strain vector in surfaces subject to stretch (up to 50% strain) and indentation. This hybrid technology will find applications in soft robotics, prosthetics and wearable health monitoring systems.

  13. Straining Ge bulk and nanomembranes for optoelectronic applications: a systematic numerical analysis

    NASA Astrophysics Data System (ADS)

    Scopece, Daniele; Montalenti, Francesco; Bollani, Monica; Chrastina, Daniel; Bonera, Emiliano

    2014-09-01

    Germanium is known to become a direct band gap material when subject to a biaxial tensile strain of 2% (Vogl et al 1993 Phys. Scr. T49B 476) or uniaxial tensile strain of 4% (Aldaghri et al 2012 J. Appl. Phys. 111 053106). This makes it appealing for the integration of optoelectronics into current CMOS technology. It is known that the induced strain is highly dependent on the geometry and composition of the whole system (stressors and substrate), leaving a large number of variables to the experimenters willing to realize this transition and just a trial-and-error procedure. The study in this paper aims at reducing this freedom. We adopt a finite element approach to systematically study the elastic strain induced by different configurations of lithographically-created SiGe nanostructures on a Ge substrate, by focusing on their composition and geometries. We numerically investigate the role played by the Ge substrate by comparing the strain induced on a bulk or on a suspended membrane. These results and their interpretation can provide the community starting guidelines to choose the appropriate subset of parameters to achieve the desired strain. A case of a very large optically active area of a Ge membrane is reported.

  14. Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

    2016-01-01

    Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

  15. Impacts of additive uniaxial strain on hole mobility in bulk Si and strained-Si p-MOSFETs

    NASA Astrophysics Data System (ADS)

    Shuo, Zhao; Lei, Guo; Jing, Wang; Jun, Xu; Zhihong, Liu

    2009-10-01

    Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained-Si (s-Si) p-MOSFETs (metal-oxide-semiconductor field-effect transistors) along (110) and (100) channel directions. In bulk Si, a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field. The combination of (100) direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the (110) direction, opposite to the situation in bulk Si. But the combinational strain experiences a gain loss at high field, which means that uniaxial compressive strain may still be a better choice. The mobility enhancement of SiGe-induced strained p-MOSFETs along the (110) direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.

  16. 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.

  17. Theoretical expectations for bulk flows in large-scale surveys

    NASA Technical Reports Server (NTRS)

    Feldman, Hume A.; Watkins, Richard

    1994-01-01

    We calculate the theoretical expectation for the bulk motion of a large-scale survey of the type recently carried out by Lauer and Postman. Included are the effects of survey geometry, errors in the distance measurements, clustering properties of the sample, and different assumed power spectra. We considered the power spectrum calculated from the Infrared Astronomy Satellite (IRAS)-QDOT survey, as well as spectra from hot + cold and standard cold dark matter models. We find that measurement uncertainty, sparse sampling, and clustering can lead to a much larger expectation for the bulk motion of a cluster sample than for the volume as a whole. However, our results suggest that the expected bulk motion is still inconsistent with that reported by Lauer and Postman at the 95%-97% confidence level.

  18. Large-scale HTS bulks for magnetic application

    NASA Astrophysics Data System (ADS)

    Werfel, Frank N.; Floegel-Delor, Uta; Riedel, Thomas; Goebel, Bernd; Rothfeld, Rolf; Schirrmeister, Peter; Wippich, Dieter

    2013-01-01

    ATZ Company has constructed about 130 HTS magnet systems using high-Tc bulk magnets. A key feature in scaling-up is the fabrication of YBCO melts textured multi-seeded large bulks with three to eight seeds. Except of levitation, magnetization, trapped field and hysteresis, we review system engineering parameters of HTS magnetic linear and rotational bearings like compactness, cryogenics, power density, efficiency and robust construction. We examine mobile compact YBCO bulk magnet platforms cooled with LN2 and Stirling cryo-cooler for demonstrator use. Compact cryostats for Maglev train operation contain 24 pieces of 3-seed bulks and can levitate 2500-3000 N at 10 mm above a permanent magnet (PM) track. The effective magnetic distance of the thermally insulated bulks is 2 mm only; the stored 2.5 l LN2 allows more than 24 h operation without refilling. 34 HTS Maglev vacuum cryostats are manufactured tested and operate in Germany, China and Brazil. The magnetic levitation load to weight ratio is more than 15, and by group assembling the HTS cryostats under vehicles up to 5 t total loads levitated above a magnetic track is achieved.

  19. High Strain-Rate Compressive Behavior of Bulk Structural Adhesives: Epoxy and Methacrylate Adhesives

    NASA Astrophysics Data System (ADS)

    Yokoyama, Takashi; Nakai, Kenji; Yatim, Norfazrina Hayati Mohd

    The present paper describes the determination of high strain-rate compressive stress-strain loops for bulk specimens of two different epoxy and methacrylate structural adhesives on the standard split Hopkinson pressure bar with a tapered striker bar. The full compressive stress-strain data including unloading process are obtained over a wide range of strain rates from 10-3 to 103/s at room temperature. The effects of strain rate on the initial (secant) modulus, flow stress, dissipation energy and hysteresis loss ratio are studied. The experimental results show that both bulk structural adhesives exhibit highly strain-rate dependent viscoelastic behavior like polymeric materials.

  20. Shear bands in a bulk metallic glass after large plastic deformation

    SciTech Connect

    Qu, D.D.; Wang, Y.B.; Liao, X.Z.; Shen, J.

    2012-10-23

    A transmission electron microscopy investigation is conducted to trace shear bands in a Zr{sub 53}Cu{sub 18.7}Ni{sub 12}Al{sub 16.3} bulk metallic glass after experiencing 4% plastic deformation. Shear band initiation, secondary shear band interactions, mature shear band broadening and the interactions of shear bands with shear-induced nanocrystals are captured. Results suggest that the plasticity of the bulk metallic glass is enhanced by complex shear bands and their interactions which accommodate large plastic strain and prevent catastrophic shear band propagation.

  1. Sheath folds as discriminators of bulk strain type

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Holdsworth, R. E.

    2006-09-01

    bulk strain type.

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

    SciTech Connect

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

    1997-07-01

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

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

    SciTech Connect

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

    1998-07-01

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

  4. Fabrication of Large Bulk High Temperature Superconducting Articles

    NASA Technical Reports Server (NTRS)

    Koczor, Ronald (Inventor); Hiser, Robert A. (Inventor)

    2003-01-01

    A method of fabricating large bulk high temperature superconducting articles which comprises the steps of selecting predetermined sizes of crystalline superconducting materials and mixing these specific sizes of particles into a homogeneous mixture which is then poured into a die. The die is placed in a press and pressurized to predetermined pressure for a predetermined time and is heat treated in the furnace at predetermined temperatures for a predetermined time. The article is left in the furnace to soak at predetermined temperatures for a predetermined period of time and is oxygenated by an oxygen source during the soaking period.

  5. Strain dependent electron spin dynamics in bulk cubic GaN

    SciTech Connect

    Schaefer, A.; Buß, J. H.; Hägele, D.; Rudolph, J.; Schupp, T.; Zado, A.; As, D. J.

    2015-03-07

    The electron spin dynamics under variable uniaxial strain is investigated in bulk cubic GaN by time-resolved magneto-optical Kerr-rotation spectroscopy. Spin relaxation is found to be approximately independent of the applied strain, in complete agreement with estimates for Dyakonov-Perel spin relaxation. Our findings clearly exclude strain-induced relaxation as an effective mechanism for spin relaxation in cubic GaN.

  6. Strain-controlled fundamental gap and structure of bulk black phosphorus

    NASA Astrophysics Data System (ADS)

    Guan, Jie; Song, Wenshen; Yang, Li; Tománek, David

    2016-07-01

    We study theoretically the structural and electronic response of layered bulk black phosphorus to in-layer strain. Ab initio density functional theory (DFT) calculations reveal that the strain energy and interlayer spacing display a strong anisotropy with respect to the uniaxial strain direction. To correctly describe the dependence of the fundamental band gap on strain, we used the computationally more involved GW quasiparticle approach that is free of parameters and is superior to DFT studies, which are known to underestimate gap energies. We find that the band gap depends sensitively on the in-layer strain and even vanishes at compressive strain values exceeding ≈2 %, thus suggesting a possible application of black P in strain-controlled infrared devices.

  7. Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect

    SciTech Connect

    Hao, Shijie; Cui, Lishan; Guo, Fangmin; Liu, Yinong; Shi, Xiaobin; Jiang, Daqiang; Brown, Dennis E.; Ren, Yang

    2015-03-09

    Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm³ that is almost one order of larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components.

  8. Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect

    NASA Astrophysics Data System (ADS)

    Hao, Shijie; Cui, Lishan; Guo, Fangmin; Liu, Yinong; Shi, Xiaobin; Jiang, Daqiang; Brown, Dennis E.; Ren, Yang

    2015-03-01

    Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm3 that is almost one order of larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components.

  9. Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect

    DOE PAGESBeta

    Hao, Shijie; Cui, Lishan; Guo, Fangmin; Liu, Yinong; Shi, Xiaobin; Jiang, Daqiang; Brown, Dennis E.; Ren, Yang

    2015-03-09

    Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm³ that is almost one order ofmore » larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components.« less

  10. Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect.

    PubMed

    Hao, Shijie; Cui, Lishan; Guo, Fangmin; Liu, Yinong; Shi, Xiaobin; Jiang, Daqiang; Brown, Dennis E; Ren, Yang

    2015-01-01

    Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm(3) that is almost one order of larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components. PMID:25749549

  11. Achieving large linear elasticity and high strength in bulk nanocompsite via synergistic effect

    PubMed Central

    Hao, Shijie; Cui, Lishan; Guo, Fangmin; Liu, Yinong; Shi, Xiaobin; Jiang, Daqiang; Brown, Dennis E.; Ren, Yang

    2015-01-01

    Elastic strain in bulk metallic materials is usually limited to only a fraction of 1%. Developing bulk metallic materials showing large linear elasticity and high strength has proven to be difficult. Here, based on the synergistic effect between nanowires and orientated martensite NiTi shape memory alloy, we developed an in-situ Nb nanowires -orientated martensitic NiTi matrix composite showing an ultra-large linear elastic strain of 4% and an ultrahigh yield strength of 1.8 GPa. This material also has a high mechanical energy storage efficiency of 96% and a high energy storage density of 36 J/cm3 that is almost one order of larger than that of spring steel. It is demonstrated that the synergistic effect allows the exceptional mechanical properties of nanowires to be harvested at macro scale and the mechanical properties of matrix to be greatly improved, resulting in these superior properties. This study provides new avenues for developing advanced composites with superior properties by using effective synergistic effect between components. PMID:25749549

  12. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  13. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  14. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  15. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

  16. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Seed in bulk or large quantities; seed for cleaning or... (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling in General § 201.33 Seed in bulk or large quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required...

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

    SciTech Connect

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

    2015-05-16

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

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

    DOE PAGESBeta

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

    2015-05-16

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

  19. Compressive behavior of bulk metallic glass under different conditions --- Coupled effect of temperature and strain rate

    NASA Astrophysics Data System (ADS)

    Yin, Weihua

    Metallic glass was first reported in 1960 by rapid quenching of Au-Si alloys. But, due to the size limitation, this material did not attract remarkable interest until the development of bulk metallic glasses (BMGs) with specimen sizes in excess of 1 mm. BMGs are considered to be promising engineering materials because of their ultrahigh strength, high elastic limit and wear resistance. However, they usually suer from a strong tendency for localized plastic deformation with catastrophic failure. Many basic questions, such as the origin of shear softening and the strain rate eect remain unclear. In this thesis, the mechanical behavior of the Zr55Al 10Ni5Cu30 bulk metallic glass and a metallic glass composite is investigated. The stress-strain relationship for Zr55Al10Ni 5Cu30 over a wide range of strain rate (5x10 --5 to 2x103 s--1) was investigated in uniaxial compression loading using both MTS servo-hydraulic system (quasi-static) and compression Kolsky bar system (dynamic). The effect of the strain rate on the fracture stress at room temperature was discussed. Based on the experimental results, the strain rate sensitivity of the bulk metallic glass changes from a positive value to a negative value at high strain rate, which is a consequence of the significant adiabatic temperature rise during the dynamic testing. In order to characterize the temperature eect on the mechanical behavior of the metallic glass, a synchronically assembled heating unit was designed to be attached onto the Kolsky bar system to perform high temperature and high strain rate mechanical testing. A transition from inhomogeneous deformation to homogeneous deformation has been observed during the quasi-static compressive experiments at testing temperatures close to the glass transition temperature. However, no transition has been observed at high strain rates at all the testing temperatures. A free volume based model is applied to analyze the stress-strain behavior of the homogeneous

  20. Experimental determination of strain partitioning among individual grains in the bulk of an aluminium multicrystal

    SciTech Connect

    Haldrup, K.

    2008-07-15

    A recently developed marker-based technique for mapping of the displacement gradient tensor and the strain throughout the bulk of optically opaque specimens is presented and applied to an aluminium alloy multicrystal. Through investigations at 4%, 10% and 14% axial strains, the internal strain field is observed to be non-homogenous with the observed patterns present throughout the range of strains investigated. The morphology of the strain field is visualized with a resolution better than 50{mu}m and variations are tentatively associated with the grain structure as recorded by EBSD. Future applications of the technique in combination with other 3-dimensional approaches are discussed with respect to comparison with Finite Element modelling approaches.

  1. Determination of third-order elastic moduli via parameters of bulk strain solitons

    NASA Astrophysics Data System (ADS)

    Garbuzov, F. E.; Samsonov, A. M.; Semenov, A. A.; Shvartz, A. G.

    2016-02-01

    A method is proposed aimed for determination of the third-order elastic moduli (Murnaghan moduli) based on the estimation of measured parameters of bulk strain solitons in the three main waveguide configurations, a rod, a plate, and a shell. Formulas connecting the third-order moduli of the waveguide material and the parameters of a solitary strain wave (amplitude, velocity, full width at half-maximum) are derived. If the soliton parameters measured in three waveguide types manufactured from the same material are available, determination of the third-order elastic moduli is reduced to the solution of a system of three algebraic equations with a nondegenerate matrix.

  2. Bulk strain solitary waves in bonded layered polymeric bars with delamination

    NASA Astrophysics Data System (ADS)

    Dreiden, G. V.; Khusnutdinova, K. R.; Samsonov, A. M.; Semenova, I. V.

    2012-09-01

    We report the registration of delamination induced variations in the dynamics of bulk strain solitary waves in layered polymeric bars with the glassy and rubber-like adhesives, for the layers made of the same material. The key phenomenon in a layered structure with the glassy bonding is the delamination caused fission of a single incident soliton into a wave train of solitons, with the detectable increase in the amplitude of the leading solitary wave. The significant feature of bulk strain solitons in structures bonded with the rubber-like adhesive is the generation of radiating solitary waves, whilst co-propagating ripples disappear in the delaminated area. The observed variations may be used for the detection of delamination in lengthy layered structures.

  3. Effect of mechanical strain on electronic properties of bulk MoS{sub 2}

    SciTech Connect

    Kumar, Sandeep Kumar, Jagdish Sastri, O. S. K. S.

    2015-05-15

    Ab-initio density functional theory based calculations of electronic properties of bulk and monolayer Molybdenum di-Sulfide (MoS{sub 2}) have been performed using all electron Full Potential Linearised Augmentad Plane Wave (FPLAPW) method using Elk code. We have used Generalised Gradient Approximation (GGA) for exchange and correlation functionals and performed calculaitons of Lattice parameters, Density Of States (DOS) and Band Structure (BS). Band structure calculations revealed that bulk MoS{sub 2} has indirect band gap of 0.97 eV and mono-layer MoS{sub 2} has direct band gap which has increased to 1.71 eV. These are in better agreement with experimental values as compared with the other calculations using pseudo-potential code. The effect of mechanical strain on the electronic properties of bulk MoS{sub 2} has also been studied. For the different values of compressive strain (varying from 2% to 8% in steps of 2%) along the c-axis, the corresponding DOS and BS are obtained. We observed that the band gap decreases by about 15% for every 2% increase in strain along the c-axis.

  4. Spin splitting in bulk wurtzite AlN under biaxial strain

    NASA Astrophysics Data System (ADS)

    Kao, Hsiu-Fen; Lo, Ikai; Chiang, Jih-Chen; Lee, Meng-En; Wu, C. L.; Wang, W. T.; Chen, Chun-Nan; Hsu, Y. C.

    2012-05-01

    The spin-splitting energies in biaxially strained bulk wurtzite material AlN are calculated using the linear combination of atomic orbital (LCAO) method, and the equi-spin-splitting distributions in k-space near the minimum-spin-splitting (MSS) surfaces are illustrated. These data are compared with those derived analytically by two-band k . p (2KP) model. It is found that the results from these two methods are in good agreement for small k. However, the ellipsoidal MSS surface under biaxial compressive strain does not exist in the 2KP model, because the data points are far from the Γ point. Instead, three basic shapes of the MSS surface occur in the wurtzite Brillouin zone: a hyperboloid of two sheets, a hexagonal cone, and a hyperboloid of one sheet, evaluated from the LCAO method across the range of biaxial strains from compressive to tensile.

  5. Characterizing large strain crush response of redwood

    SciTech Connect

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

    1996-12-01

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

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

    SciTech Connect

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

    2014-11-17

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

  7. Effect of high strain rates on peak stress in a Zr-based bulk metallic glass

    SciTech Connect

    Sunny, George; Yuan Fuping; Prakash, Vikas; Lewandowski, John

    2008-11-01

    The mechanical behavior of Zr{sub 41.25}Ti{sub 13.75}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (LM-1) has been extensively characterized under quasistatic loading conditions; however, its mechanical behavior under dynamic loading conditions is currently not well understood. A Split-Hopkinson pressure bar (SHPB) and a single-stage gas gun are employed to characterize the mechanical behavior of LM-1 in the strain-rate regime of 10{sup 2}-10{sup 5}/s. The SHPB experiments are conducted with a tapered insert design to mitigate the effects of stress concentrations and preferential failure at the specimen-insert interface. The higher strain-rate plate-impact compression-and-shear experiments are conducted by impacting a thick tungsten carbide (WC) flyer plate with a sandwich sample comprising a thin bulk metallic glass specimen between two thicker WC target plates. Specimens employed in the SHPB experiments failed in the gage-section at a peak stress of approximately 1.8 GPa. Specimens in the high strain-rate plate-impact experiments exhibited a flow stress in shear of approximately 0.9 GPa, regardless of the shear strain-rate. The flow stress under the plate-impact conditions was converted to an equivalent flow stress under uniaxial compression by assuming a von Mises-like material behavior and accounting for the plane strain conditions. The results of these experiments, when compared to the previous work conducted at quasistatic loading rates, indicate that the peak stress of LM-1 is essentially strain rate independent over the strain-rate range up to 10{sup 5}/s.

  8. High-zirconium bulk metallic glasses with high strength and large ductility

    NASA Astrophysics Data System (ADS)

    Yang, YaoWei; Hua, NengBin; Li, Ran; Pang, ShuJie; Zhang, Tao

    2013-03-01

    In this paper, high-zirconium Zr66+2 x Al9- x (Ni1/3Cu2/3)25- x ( x=0,1,2 at.%) bulk metallic glasses with high strength and large ductility were fabricated by copper mould casting. The effects of zirconium content on the glass-forming ability (GFA), thermal properties and mechanical properties were investigated using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and mechanical testing system in compressive and three-point bending modes, respectively. The high-zirconium BMGs show the critical diameters of 3-5 mm, the supercooled liquid region ranging from 70 K to 99 K, and the yield strength of over 1700 MPa. The Zr70Al7(Ni1/3Cu2/3)23 BMG exhibits a large compressive plastic strain up to 21% and a high notch toughness value of 60.6 MPa m1/2. The increase in Zr content results in the decrease in GFA and thermostability, and in the improvement of plasticity under compressive and three-point bending conditions. The superior plasticity of high-zirconium BMGs is attributed to their high Poisson's ratio and small elastic modulus ratio µ/ B.

  9. Tuning quantum dot luminescence below the bulk band gap using tensile strain.

    PubMed

    Simmonds, Paul J; Yerino, Christopher D; Sun, Meng; Liang, Baolai; Huffaker, Diana L; Dorogan, Vitaliy G; Mazur, Yuriy; Salamo, Gregory; Lee, Minjoo Larry

    2013-06-25

    Self-assembled quantum dots (SAQDs) grown under biaxial tension could enable novel devices by taking advantage of the strong band gap reduction induced by tensile strain. Tensile SAQDs with low optical transition energies could find application in the technologically important area of mid-infrared optoelectronics. In the case of Ge, biaxial tension can even cause a highly desirable crossover from an indirect- to a direct-gap band structure. However, the inability to grow tensile SAQDs without dislocations has impeded progress in these directions. In this article, we demonstrate a method to grow dislocation-free, tensile SAQDs by employing the unique strain relief mechanisms of (110)-oriented surfaces. As a model system, we show that tensile GaAs SAQDs form spontaneously, controllably, and without dislocations on InAlAs(110) surfaces. The tensile strain reduces the band gap in GaAs SAQDs by ~40%, leading to robust type-I quantum confinement and photoluminescence at energies lower than that of bulk GaAs. This method can be extended to other zinc blende and diamond cubic materials to form novel optoelectronic devices based on tensile SAQDs. PMID:23701255

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

    NASA Astrophysics Data System (ADS)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

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

  11. 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. Large-Strain Transparent Magnetoactive Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    2012-01-01

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

  13. Effect of Large Bulk Viscosity on Two-Dimensional Transonic Flow

    NASA Astrophysics Data System (ADS)

    Cramer, Mark

    2012-11-01

    We examine steady two-dimensional transonic flows over a thin airfoil or turbine blade. The wing Reynolds number is taken to be large and the fluid is described by the classical Navier-Stokes equations. The bulk viscosity is taken to be large compared to the shear viscosity. We use the Method of Matched Asymptotic Expansions to give the conditions under which the effects of large bulk viscosity are no longer negligible. We show that longitudinal viscous effects must be considered at lowest order when the ratio of bulk to shear viscosity is on the order of the product of the conventional Reynolds number times the two-thirds power of the non-dimensional airfoil thickness. Under these conditions the flow is shown to be frictional, irrotational, and governed by the viscous form of the transonic small disturbance equation. This work was supported by NSF Grant CBET-0625015.

  14. Wideband model of a reflective tensile-strained bulk semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Connelly, M. J.

    2014-05-01

    Reflective semiconductor optical amplifiers (RSOAs) have shown promise for applications in WDM optical networks and in fiber ring mode-locked lasers. Polarization insensitive SOAs can be fabricated using tensile-strained bulk material and a rectangular cross section waveguide. The introduction of tensile strain can be used to compensate for the different confinement factors experienced by the waveguide TE and TM modes. There is a need for models that can be used to predict RSOA static characteristics such as the dependency of the signal gain on bias current and input optical power, the amplified spontaneous emission spectrum and noise figure. In this paper we extend our prior work on non-reflective SOAs to develop a static model that includes facet reflections. The model uses a detailed band structure description, which is used to determine the wavelength and carrier density dependency of the material gain and additive spontaneous emission. The model and includes a full geometrical description of the amplifier waveguide, including the input taper and the position dependency of the TE/TM confinement factors. The amplified signal and spontaneous emission are described by detailed travelling-wave equations and numerically solved in conjunction with a carrier density rate equation. The model uses material and geometric parameters for a commercially available RSOA. The versatility of the model is shown by several simulations that are used to predict the SOA operational characteristics as well as internal variables such as the amplified spontaneous emission and signal and the carrier density.

  15. Electronic properties of polycrystalline graphene under large local strain

    SciTech Connect

    He, Xin; Tang, Ning E-mail: geweikun@mail.tsinghua.edu.cn Duan, Junxi; Mei, Fuhong; Meng, Hu; Lu, Fangchao; Xu, Fujun; Yang, Xuelin; Gao, Li; Wang, Xinqiang; Shen, Bo E-mail: geweikun@mail.tsinghua.edu.cn; Ge, Weikun E-mail: geweikun@mail.tsinghua.edu.cn

    2014-06-16

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

  16. Interpretation of large-strain geophysical crosshole tests

    SciTech Connect

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

    1995-10-01

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

  17. Bulk arc strain, crustal thickening, magma emplacement, and mass balances in the Mesozoic Sierra Nevada arc

    NASA Astrophysics Data System (ADS)

    Cao, Wenrong; Paterson, Scott; Saleeby, Jason; Zalunardo, Sean

    2016-03-01

    Quantifying crustal deformation is important for evaluating mass balance, material transfer, and the interplay between tectonism and magmatism in continental arcs. We present a dataset of >650 finite strain analyses compiled from published works and our own studies with associated structural, geochronologic, and geobarometric information in central and southern Sierra Nevada, California, to quantify the arc crust deformation. Our results show that Mesozoic tectonism results in 65% arc-perpendicular bulk crust shortening under a more or less plane strain condition. Mesozoic arc magmatism replaced ∼80% of this actively deforming arc crust with plutons requiring significantly greater crustal thickening. We suggest that by ∼85 Ma, the arc crust thickness was ∼80 km with a 30-km-thick arc root, resulting in a ∼5 km elevation. Most tectonic shortening and magma emplacement must be accommodated by downward displacements of crustal materials into growing crustal roots at the estimated downward transfer rate of 2-13 km/Myr. The downward transfer of crustal materials must occur in active magma channels, or in "escape channels" in between solidified plutons that decrease in size with time and depth resulting in an increase in the intensity of constrictional strain with depth. We argue that both tectonism and magmatism control the thickness of the crust and surface elevation with slight modification by surface erosion. The downward transported crustal materials initially fertilize the MASH zone thus enhancing to the generation of additional magmas. As the crustal root grows it may potentially pinch out and cool the mantle wedge and thus cause reduction of arc magmatism.

  18. 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

  19. Measurement of large strains in ropes using plastic optical fibers

    DOEpatents

    Williams, Jerry Gene; Smith, David Barton; Muhs, Jeffrey David

    2006-02-14

    A method for the direct measurement of large strains in ropes in situ using a plastic optical fiber, for example, perfluorocarbon or polymethyl methacrylate and Optical Time-Domain Reflectometer or other light time-of-flight measurement instrumentation. Protective sheaths and guides are incorporated to protect the plastic optical fiber. In one embodiment, a small rope is braided around the plastic optical fiber to impose lateral compressive forces to restrain the plastic optical fiber from slipping and thus experience the same strain as the rope. Methods are described for making reflective interfaces along the length of the plastic optical fiber and to provide the capability to measure strain within discrete segments of the rope. Interpretation of the data allows one to calculate the accumulated strain at any point in time and to determine if the rope has experienced local damage.

  20. Analysis of Bulk and Thin Film Model Samples Intended for Investigating the Strain Sensitivity of Niobium-Tin

    SciTech Connect

    Mentink, M. G. T.; Anders, A.; Dhalle, M. M. J.; Dietderich, D. R.; Godeke, A.; Goldacker, W.; Hellman, F.; Kate, H. H. J. ten; Putnam, D.; Slack, J. L.; Sumption, M. D.; Susner, M. A.

    2010-08-01

    Bulk samples and thin films were fabricated and characterized to determine their suitability for studying the effect of composition and morphology on strain sensitivity. Heat capacity and resistivity data are used to determine the critical temperature distribution. It is found that all bulk samples contain stoichiometric Nb{sub 3}Sn regardless of their nominal Nb to Sn ratio. Furthermore, in bulk samples with Cu additions, a bi-modal distribution of stoichiometric and off-stoichiometric Nb-Sn is found. Thus the nominally off-stoichiometric bulk samples require additional homogenization steps to yield homogeneous off-stoichiometric samples. A binary magnetron-sputtered thin film has the intended off-stoichiometric Nb-Sn phase with a mid-point critical temperature of 16.3 K. This type of sample is a suitable candidate for investigating the strain sensitivity of A15 Nb{sub 1-{beta}}Sn{sub {beta}}, with 0.18 < {beta} < 0.25. The strain sensitivity of Nb-Sn as a function of composition and morphology is important for an in-depth understanding of the strain sensitivity of composite Nb{sub 3}Sn wires.

  1. Sprayable birefringent coating enables strain measurements on large surfaces

    NASA Technical Reports Server (NTRS)

    Humphrey, F. T.; Mcgee, W. M.

    1966-01-01

    Birefringent coating for strain measurements on large surfaces contains constituents that can be premixed and sprayed as a single component with conventional paint spray equipment. Elevated temperatures are not required for spraying or curing of the coating material which has long pot life.

  2. Large Strain Transparent Magneto-Active Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  3. WIPP Benchmark calculations with the large strain SPECTROM codes

    SciTech Connect

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

    1995-08-01

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

  4. Large bulk-yard 3D measurement based on videogrammetry and projected contour aiding

    NASA Astrophysics Data System (ADS)

    Ou, Jianliang; Zhang, Xiaohu; Yuan, Yun; Zhu, Xianwei

    2011-07-01

    Fast and accurate 3D measurement of large stack-yard is important job in bulk load-and-unload and logistics management. Stack-yard holds its special characteristics as: complex and irregular shape, single surface texture and low material reflectivity, thus its 3D measurement is quite difficult to be realized by traditional non-contacting methods, such as LiDAR(LIght Detecting And Ranging) and photogrammetry. Light-section is good at the measurement of small bulk-flow but not suitable for large-scale bulk-yard yet. In the paper, an improved method based on stereo cameras and laser-line projector is proposed. The due theoretical model is composed from such three key points: corresponding point of contour edge matching in stereo imagery based on gradient and epipolar-line constraint, 3D point-set calculating for stereo imagery projected-contour edge with least square adjustment and forward intersection, then the projected 3D-contour reconstructed by RANSAC(RANdom SAmpling Consensus) and contour spatial features from 3D point-set of single contour edge. In this way, stack-yard surface can be scanned easily by the laser-line projector, and certain region's 3D shape can be reconstructed automatically by stereo cameras on an observing position. Experiment proved the proposed method is effective for bulk-yard 3D measurement in fast, automatic, reliable and accurate way.

  5. Electrospun Fibrous Membranes with Super-large-strain Electric Superhydrophobicity

    NASA Astrophysics Data System (ADS)

    Zhou, Hua; Wang, Hongxia; Niu, Haitao; Lin, Tong

    2015-10-01

    Large-strain elastic superhydrophobicity is highly desirable for its enhanced use performance and functional reliability in mechanically dynamic environments, but remains challenging to develop. Here we have, for the first time, proven that an elastic fibrous membrane after surface hydrophobization can maintain superhydrophobicity during one-directional (uniaxial) stretching to a strain as high as 1500% and two-direction (biaxial) stretching to a strain up to 700%. The fibrous membrane can withstand at least 1,000 cycles of repeated stretching without losing the superhydrophobicity. Stretching slightly increases the membrane air permeability and reduces water breakthrough pressure. It is highly stable in acid and base environments. Such a permeable, highly-elastic superhydrophobic membrane may open up novel applications in membrane separation, healthcare, functional textile and energy fields.

  6. Electrospun Fibrous Membranes with Super-large-strain Electric Superhydrophobicity

    PubMed Central

    Zhou, Hua; Wang, Hongxia; Niu, Haitao; Lin, Tong

    2015-01-01

    Large-strain elastic superhydrophobicity is highly desirable for its enhanced use performance and functional reliability in mechanically dynamic environments, but remains challenging to develop. Here we have, for the first time, proven that an elastic fibrous membrane after surface hydrophobization can maintain superhydrophobicity during one-directional (uniaxial) stretching to a strain as high as 1500% and two-direction (biaxial) stretching to a strain up to 700%. The fibrous membrane can withstand at least 1,000 cycles of repeated stretching without losing the superhydrophobicity. Stretching slightly increases the membrane air permeability and reduces water breakthrough pressure. It is highly stable in acid and base environments. Such a permeable, highly-elastic superhydrophobic membrane may open up novel applications in membrane separation, healthcare, functional textile and energy fields. PMID:26511520

  7. Fabrication of pixilated architecture large panel organic flexible solar cell by reducing bulk electrical resistance

    NASA Astrophysics Data System (ADS)

    Panag, Jasmeet Singh

    This study investigates experimentally the photovoltaic behavior and performance of a new pixilated architecture of large organic photovoltaic panels made of a large array of high-aspect ratio three-dimensional pillars surrounded by a matrix of polymer photoactive material. A least addressed problem in organic and thin-film solar cells is the high bulk resistance of cathodic and anodic layers that result in drastic reduction of currents and power conversion efficiency (PCE). For such panels to be practical and commercially competitive, this huge bulk-resistance has to be minimized as much as possible. In this study, therefore, we introduce a new novel architecture that essentially compartmentalizes large panels into smaller modules that are connected to each other in a parallel fashion. In this architecture, the metal cathode layer is applied on the top as a series of lines whereas the anodic layer is independently connected to the pixilated cells at the bottom. As a result, these modules act like independent pixel cells wherein the damage from process and operation is limited individual pixel cells. The factors considered in validating the pixilated architecture presented here consisted of effect of number of pixels on efficiency and bulk electrical resistance. In addition, the study shows that pixilated architecture offers more uniform photoactive layers, and hence better photovoltaic performance because of the compartmentalization.

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

    NASA Astrophysics Data System (ADS)

    Yi, Weijing

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

  9. Band-gap shrinkage calculations and analytic model for strained bulk InGaAsP

    NASA Astrophysics Data System (ADS)

    Connelly, Michael J.

    2015-02-01

    Band-gap shrinkage is an important effect in semiconductor lasers and optical amplifiers. In the former it leads to an increase in the lasing wavelength and in the latter an increase in the gain peak wavelength as the bias current is increased. The most common model used for carrier-density dependent band-gap shrinkage is a cube root dependency on carrier density, which is strictly only true for high carrier densities and low temperatures. This simple model, involves a material constant which is treated as a fitting parameter. Strained InGaAsP material is commonly used to fabricate polarization insensitive semiconductor optical amplifiers (SOAs). Most mathematical models for SOAs use the cube root bandgap shrinkage model. However, because SOAs are often operated over a wide range of drive currents and input optical powers leading to large variations in carrier density along the amplifier length, for improved model accuracy it is preferable to use band-gap shrinkage calculated from knowledge of the material bandstructure. In this letter the carrier density dependent band-gap shrinkage for strained InGaAsP is calculated by using detailed non-parabolic conduction and valence band models. The shrinkage dependency on temperature and both tensile and compressive strain is investigated and compared to the cube root model, for which it shows significant deviation. A simple power model, showing an almost square-root dependency, is derived for carrier densities in the range usually encountered in InGaAsP laser diodes and SOAs.

  10. New materials for large-strain actuator applications

    NASA Astrophysics Data System (ADS)

    Rittenmyer, Kurt M.; Ting, Robert Y.

    1994-05-01

    Several new materials capable of generating large strains under an electric field are being developed for applications as actuators and high-drive sonar projectors. These materials are capable of generating strains that are several times large than those produced by conventional lead zirconate-titanate ceramics. The first group of materials are the class of lead magnesium niobate-lead titanate (PMNPT) ceramics. These materials are electrostrictive and, therefore, are operated under dc bias fields. The largest strains are obtained when the temperature is maintained in the region of the order-disorder phase transition of the material. This, however, makes the properties of the material temperature dependent. An alternative material is the family of lanthanum-modified lead zirconate-titanate (PLZT) ceramics. These materials have been developed extensively for electro-optic applications. They can generate even higher levels of strain compared with the PMNPT ceramics with less temperature dependence. They, however, suffer from higher dielectric hysteresis and are more suitable for actuator applications because of dielectric heating. Results are presented for measurements on several compositions of PMNPT and PLZT.

  11. How large grains increase bulk friction in bi-disperse granular chute flows

    NASA Astrophysics Data System (ADS)

    Staron, Lydie; Phillips, Jeremy C.

    2016-07-01

    In this contribution, we apply contact dynamics discrete simulations to explore how the mechanical properties of simple bi-dimensional granular chute flows are affected by the existence of two grain sizes. Computing partial stress tensors for the phases of small and large grains, we show that the phase of large grain exhibits a much larger shear strength than the phase of small grains. This difference translates in terms of the flow internal friction: adopting the μ (I) dependence to describe the flow frictional properties, we establish that the flow mean friction coefficient increases with the volume fraction of large grains. Hence, while the presence of large grains may induce lubrication in 3D unconfined flows due to the self-channelisation and levées formation, the effect of large grains on the bulk properties is to decrease the flow mobility.

  12. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  13. Compliant composite electrodes and large strain bistable actuation

    NASA Astrophysics Data System (ADS)

    Yun, Sungryul; Yu, Zhibin; Niu, Xiaofan; Hu, Weili; Li, Lu; Brochu, Paul; Pei, Qibing

    2012-04-01

    Dielectric elastomer actuators (DEA) and bistable electroactive polymers (BSEP) both require compliant electrodes with rubbery elasticity and high conductivity at large strains. Stretchable opto-electronic devices additionally require the compliant electrodes to be optically transparent. Many candidate materials have been investigated. We report a new approach to mechanically robust, stretchable compliant electrodes. A facile in-situ composite synthesis and transfer technique is employed, and the resulting composite electrodes retain the high surface conductivity of the original conductive network formed by nanowires or nanotubes, while exhibiting the mechanical flexibility of the matrix polymer. The composite electrodes have high transparency and low surface roughness useful for the fabrication of polymer thinfilm electronic devices. The new electrodes are suitable for high-strain actuation, as a complaint resistive heating element to administer the temperature of shape memory polymers, and as the charge injection electrodes for flexible/stretchable polymer light emitting diodes. Bistable electroactive polymers employing the composite electrodes can be actuated to large strains via heating-actuation-cooling cycles.

  14. Modeling Large-Strain, High-Rate Deformation in Metals

    SciTech Connect

    Lesuer, D R; Kay, G J; LeBlanc, M M

    2001-07-20

    The large strain deformation response of 6061-T6 and Ti-6Al-4V has been evaluated over a range in strain rates from 10{sup -4} s{sup -1} to over 10{sup 4} s{sup -1}. The results have been used to critically evaluate the strength and damage components of the Johnson-Cook (JC) material model. A new model that addresses the shortcomings of the JC model was then developed and evaluated. The model is derived from the rate equations that represent deformation mechanisms active during moderate and high rate loading. Another model that accounts for the influence of void formation on yield and flow behavior of a ductile metal (the Gurson model) was also evaluated. The characteristics and predictive capabilities of these models are reviewed.

  15. Large anisotropic thermal transport properties observed in bulk single crystal black phosphorus

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Xu, Guizhou; Hou, Zhipeng; Yang, Bingchao; Zhang, Xiaoming; Liu, Enke; Xi, Xuekui; Liu, Zhongyuan; Zeng, Zhongming; Wang, Wenhong; Wu, Guangheng

    2016-02-01

    The anisotropy of thermal transport properties for bulk black phosphorus (BP) single crystal, which might be of particular interest in the fabrication of thermoelectric/optoelectronic devices, was investigated by using angular dependent thermal conductivity and Seebeck coefficient measurements at various temperatures. We found that the maximum thermal conductivities in x (zigzag), y (armchair), and z (perpendicular to the puckered layers) directions are 34, 17, and 5 W m-1 K-1, respectively, exhibiting large anisotropy. At temperature around 200 K, a large Seebeck coefficient up to +487 ± 10 μV/K has been obtained in x direction, which is 1.5 times higher than that in z direction. The large anisotropy of thermal transport properties can be understood from the crystal structure and bonding characters of BP. In addition, the energy gap has been obtained from nuclear spin lattice relaxation measurements, which is consistent with the value derived from temperature-dependent Seebeck coefficient measurements.

  16. Structures in an anhydrite layer embedded in halite matrix: Results from thermomechanical experiments under bulk plain strain

    NASA Astrophysics Data System (ADS)

    Mertineit, M.; Zulauf, G.; Peinl, M.; Zanella, F.; Bornemann, O.

    2009-04-01

    considers rheological parameters. Moreover experiments carried out under bulk constrictional strain (Zulauf et al., 2007, 2009) show a similar dependency of the initial layer thickness and boudin width. For microstructual investigations of the halite matrix, thin sections (XZ- and YZ-sections) were prepared and etched following the method of Urai et al. (1987). First microfabric data show that halite behaves viscous whereas anhydrite deforms by fracturing or rare folding under the chosen deformation conditions. Halite deforms by climb-controlled dislocation creep with strain hardening (Carter et al., 1993). Anhydrite, on the other hand, was deformed in the brittle-plastic regime, characterized by twinning, kinking and fracturing. The subgrain size of halite has been used to estimate the differential stress (Schléder & Urai, 2005, 2007), that was compared with the stress recorded by the load cells. The subgrain size of deformed halite varies between 0.04 and 0.07mm, resulting in differential stresses between 3.3 +1.5/-0.8 MPa (S⊥X) and 4.2 +3.0/-1.2 MPa (S⊥Z), although the conditions for piezometry are not completely fulfilled (e.g. lack of steady state during deformation in some samples). These stress values in the matrix fit with the stress values recorded during deformation. Close to rigid anhydrite the subgrain size decreases to values of 0.02 - 0.03 mm, reflecting peak stress up to 6.7 +3.7/-0.7 MPa. We do not know the reasons why folding of the anhydrite layer is largely lacking, although the viscosity contrast between halite and anhydrite should be appropriate for folding. Possible reasons are the lack in confining pressure or mechanical anisotropies in the undeformed anhydrite. Further investigations will focus on the texture of halite and on microfabrics of the anhydrite. References Carter, N.L., Horseman, S.T., Russel, J.E. & Handin, J (1993): Rheology of rocksalt, J. Struct. Geol., Vol. 15, No. 9/10, p. 1257-1271 Price, N.J.; Cosgrove, J.W. (1990

  17. Large Scale 3-D Dislocation Dynamics and Atomistic Simulations of Flow and Strain-Hardening Behavior of Metallic Micropillars

    NASA Astrophysics Data System (ADS)

    Rao, Satish

    2015-03-01

    Experimental studies show strong strengthening effects for micrometer-scale FCC as well as two-phase superalloy crystals, even at high initial dislocation densities. This talk shows results from large-scale 3-D discrete dislocation simulations (DDS) used to explicitly model the deformation behavior of FCC Ni (flow stress and strain-hardening) as well as superalloy microcrystals for diameters ranging from 1 - 20 microns. The work shows that two size-sensitive athermal hardening processes, beyond forest and precipitation hardening, are sufficient to develop the dimensional scaling of the flow stress, stochastic stress variation, flow intermittency and, high initial strain-hardening rates, similar to experimental observations for various materials. In addition, 3D dislocation dynamics simulations are used to investigate strain-hardening characteristics and dislocation microstructure evolution with strain in large 20 micron size Ni microcrystals (bulk-like) under three different loading axes: 111, 001 and 110. Three different multi-slip loading axes, < 111 > , < 001 > and < 110 > , are explored for shear strains of ~0.03 and final dislocation densities of ~1013/m2. The orientation dependence of initial strain hardening rates and dislocation microstructure evolution with strain are discussed. The simulated strain hardening results are compared with experimental data under similar loading conditions from bulk single-crystal Ni. Finally, atomistic simulation results on the operation of single arm sources in Ni bipillars with a large angle grain boundary is discussed. The atomistic simulation results are compared with experimental mechanical behavior data on Cu bipillars with a similar large angle grain boundary. This work was supported by AFOSR (Dr. David Stargel), and by a grant of computer time from the DOD High Performance Computing Modernization Program, at the Aeronautical Systems Center/Major Shared Resource Center.

  18. Lead-free ternary perovskite compounds with large electromechanical strains

    NASA Astrophysics Data System (ADS)

    Jarupoom, Parkpoom; Patterson, Eric; Gibbons, Brady; Rujijanagul, Gobwute; Yimnirun, Rattikorn; Cann, David

    2011-10-01

    Lead-free compounds based on perovskite solid solutions in the ternary system (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-Bi(X1/2Ti1/2)O3, where X = Ni and Mg have been shown to exhibit large electromechanical strains. While the perovskite end members Bi(Mg1/2Ti1/2)O3 and Bi(Ni1/2Ti1/2)O3 display limited stability in their pure state, both compounds were found to have solid solubilities of at least 50 mol. % with (Bi1/2Na1/2)TiO3 and (Bi1/2K1/2)TiO3. Most importantly, under relatively large applied fields, these materials exhibited large hysteretic electromechanical strains characterized by a parabolic shape. With effective piezoelectric coefficients (d33*) greater than 500 pm/V, these systems have excellent potential as a Pb-free piezoelectric materials.

  19. The visioplastic method for analysis of large extrusion strains

    SciTech Connect

    Peacock, H. ); Berghaus, D. . School of Civil Engineering)

    1990-01-01

    Large plastic strains are produced when a metal billet is pressed through an extrusion die. This paper describes a method for obtaining the distribution of these strains during axisymmetric extrusion. The method is experimental-numerical and is based on a study of laminar flow lines produced in the extruded material. Several results are obtained using this analysis. These include the effects of extrusion tooling temperature and extrusion ratio. The method is also modified to study extrusion of powder metal, where the variable density invalidates the usual assumption of incompressibility. The flowline-strain relationship was originally set forth by Thomsen, Yang and Kobayashi and is referred to as viscoplasticity. The method described in this paper proceeds from that developed by Medrano and Gillis for axisymmetric extrusion. There are several differences. The experimental procedure has been changed to permit extrusion analysis at the high aluminum forming temperature (up to 430{degrees}C), thus allowing temperature effects to be studied. Numerical improvements permit the analysis at high extrusion ratios. The flow function has been redefined to permit the study of variable density material. 6 refs., 8 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

    Polyzois, Ioannis

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

  1. Bulk glassy Cu-based alloys with a large supercooled liquid region of 110 K

    NASA Astrophysics Data System (ADS)

    Inoue, Akihisa; Zhang, Wei

    2003-09-01

    The replacement of Cu by 5%Ag for Cu50Hf45Al5 glassy alloy was found to increase significantly the stability of supercooled liquid against crystallization. The supercooled liquid region reached as large as 110 K for Cu45Hf45Al5Ag5. The extension of the supercooled liquid region is due to an increase in the crystallization temperature, accompanying the change in the primary crystalline phases. The effectiveness of Ag addition was interpreted to result from the retardation of long-range atomic rearrangements for the progress of crystallization reaction. The selection of the quaternary composition enabled us to form bulk glassy alloys with diameters up to 3 mm. The Young's modulus and compressive fracture strength of the 5%Ag-containing alloy are 119 GPa and 2220 MPa, respectively.

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

    NASA Astrophysics Data System (ADS)

    Latka, Ines; Habisreuther, Tobias; Zeisberger, Matthias

    2009-07-01

    A new optical method for the characterization of magnetostrictive effects in bulk superconductors will be presented. Several of wavelength encoded fiber Bragg gratings can be inscribed in one fiber with small spatial distances, which gives the possibility to measure magnetostrictive effects spatially resolved. To demonstrate the performance, samples with Bragg grating arrays glued onto the surface of an YBCO disk where tested in a superconducting solenoid at temperatures of 60 K and magnetic inductances of 6.5 T. For the first time the radius position dependent strain and not only sum effects could be measured. It was stated that in the remnant state both, elongating and compressive strain, occur. This is in agreement with our simulations.

  3. Fast inspection of bulk and surface defects of large aperture optics in high power lasers

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan'an; Hu, Guohang; Liu, Shijie; Yi, Kui; Shao, Jianda

    2015-05-01

    Laser induced damage for nanosecond pulse duration is attributed to the existence of defects. The growth and polishing, as well as coating deposition, may induce versatile kinds of defects, including dig, scratch and inclusion. It is special important to get the information of the defects, such as size and location, which is the basis to know the origin of the defects and figures out effective techniques to eliminate it. It is quite easy to get the information of the defects with micron-level resolution, but it is time-consuming and is not suitable for fast inspection of the large aperture (hundreds of millimeters). In this work, on-the-fly image capture technique was employed to realize fast inspection of large aperture optics. A continuous green laser was employed as illumination source to enhance and enlarge the image of bulk defects. So it could detect the submicron-scale defects. A transmission microscopy with white light illumination was employed to detect the surface defect. Its field of view was about 2.8mm×1.6mm. The sample was raster scanned driving by a stepper motor through the stationary illumination laser and digital camera, and the speed to scan the sample was about 10mm/s. The results of large aperture optics proved the functions of this fast inspection technique.

  4. A flux extraction device to measure the magnetic moment of large samples; application to bulk superconductors.

    PubMed

    Egan, R; Philippe, M; Wera, L; Fagnard, J F; Vanderheyden, B; Dennis, A; Shi, Y; Cardwell, D A; Vanderbemden, P

    2015-02-01

    We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm(3)) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m(2) (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K). PMID:25725888

  5. A flux extraction device to measure the magnetic moment of large samples; application to bulk superconductors

    NASA Astrophysics Data System (ADS)

    Egan, R.; Philippe, M.; Wera, L.; Fagnard, J. F.; Vanderheyden, B.; Dennis, A.; Shi, Y.; Cardwell, D. A.; Vanderbemden, P.

    2015-02-01

    We report the design and construction of a flux extraction device to measure the DC magnetic moment of large samples (i.e., several cm3) at cryogenic temperature. The signal is constructed by integrating the electromotive force generated by two coils wound in series-opposition that move around the sample. We show that an octupole expansion of the magnetic vector potential can be used conveniently to treat near-field effects for this geometrical configuration. The resulting expansion is tested for the case of a large, permanently magnetized, type-II superconducting sample. The dimensions of the sensing coils are determined in such a way that the measurement is influenced by the dipole magnetic moment of the sample and not by moments of higher order, within user-determined upper bounds. The device, which is able to measure magnetic moments in excess of 1 A m2 (1000 emu), is validated by (i) a direct calibration experiment using a small coil driven by a known current and (ii) by comparison with the results of numerical calculations obtained previously using a flux measurement technique. The sensitivity of the device is demonstrated by the measurement of flux-creep relaxation of the magnetization in a large bulk superconductor sample at liquid nitrogen temperature (77 K).

  6. Transparent Large Strain Thermoplastic Polyurethane Magneto-Active Nanocomposites

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Carpen, Ileana; Peck, John; Sola, Francisco; Bail, Justin; Lerch, Bradley; Meador, Michael

    2010-01-01

    Smart adaptive materials are an important class of materials which can be used in space deployable structures, morphing wings, and structural air vehicle components where remote actuation can improve fuel efficiency. Adaptive materials can undergo deformation when exposed to external stimuli such as electric fields, thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation, and magnetic field. Large strain, controlled and repetitive actuation are important characteristics of smart adaptive materials. Polymer nanocomposites can be tailored as shape memory polymers and actuators. Magnetic actuation of polymer nanocomposites using a range of iron, iron cobalt, and iron manganese nanoparticles is presented. The iron-based nanoparticles were synthesized using the soft template (1) and Sun's (2) methods. The nanoparticles shape and size were examined using TEM. The crystalline structure and domain size were evaluated using WAXS. Surface modifications of the nanoparticles were performed to improve dispersion, and were characterized with IR and TGA. TPU nanocomposites exhibited actuation for approximately 2wt% nanoparticle loading in an applied magnetic field. Large deformation and fast recovery were observed. These nanocomposites represent a promising potential for new generation of smart materials.

  7. On the anelasticity and strain induced structural changes in a Zr-based bulk metallic glass

    SciTech Connect

    Caron, A.; Louzguine-Luzguin, D. V.; Kawashima, A.; Inoue, A.; Fecht, H.-J.

    2011-10-24

    We report on the anelastic behavior of a cyclically loaded Zr{sub 62.5}Fe{sub 5}Cu{sub 22.5}Al{sub 10} bulk metallic glass well below its yield strength. The dynamic mechanical behavior of the glass is discussed on the basis of its structural and thermodynamic properties before and after tests. We show how the kinetically frozen anelastic deformation accumulates at room temperature and causes a structural relaxation and densification of the glass and further leads to its partial crystallization.

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

    NASA Astrophysics Data System (ADS)

    Purcaru, G.

    2004-12-01

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

  9. Studies of Shear Band Velocity Using Spatially and Temporally Resolved Measurements of Strain During Quasistatic Compression of Bulk Metallic Glass

    SciTech Connect

    Wright, W J; Samale, M; Hufnagel, T; LeBlanc, M; Florando, J

    2009-06-15

    We have made measurements of the temporal and spatial features of the evolution of strain during the serrated flow of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass tested under quasistatic, room temperature, uniaxial compression. Strain and load data were acquired at rates of up to 400 kHz using strain gages affixed to all four sides of the specimen and a piezoelectric load cell located near the specimen. Calculation of the displacement rate requires an assumption about the nature of the shear displacement. If one assumes that the entire shear plane displaces simultaneously, the displacement rate is approximately 0.002 m/s. If instead one assumes that the displacement occurs as a localized propagating front, the velocity of the front is approximately 2.8 m/s. In either case, the velocity is orders of magnitude less than the shear wave speed ({approx}2000 m/s). The significance of these measurements for estimates of heating in shear bands is discussed.

  10. Experimental study of cancellous bone under large strains and a constitutive probabilistic model.

    PubMed

    Kefalas, V; Eftaxiopoulos, D A

    2012-02-01

    Experimental study of bovine cancellous bone up to compaction under uniaxial compression and up to fracture under tension, has been pursued in this article. Compression experiments have revealed the known three stages of the constitutive response, namely the initial increasing and softening branches at moderate strains, the plateau region at large strains and the hardening part at very large strains under compaction. Tension tests have quantified the increasing and softening branches of the stress-strain curve up to fracture. Subsequently, a constitutive mechanical model, for the simulation of the experimental findings up to very large strains (75% engineering strain under compression), is proposed. The model is based on the statistical description of (a) the failure process of the trabecular structure at small and moderate strains and (b) the compaction process of the trabecular mass at very large strains under compression. Several fitting cases indicated that the presented constitutive law can capture the evolution of the experimental results. PMID:22301172

  11. Silicon doping of HVPE GaN bulk-crystals avoiding tensile strain generation

    NASA Astrophysics Data System (ADS)

    Hofmann, Patrick; Röder, Christian; Habel, Frank; Leibiger, Gunnar; Beyer, Franziska C.; Gärtner, Günter; Eichler, Stefan; Mikolajick, Thomas

    2016-02-01

    Doped GaN:Si crystals were grown in a commercially available vertical HVPE reactor. The templates used for the HVPE heteroepitaxy were so-called FACELO seeds, with a starting GaN layer thickness of 3-4 μm. The FWHM of the 0002 and the 30\\bar{3}2 reflection of the HVPE-grown GaN:Si crystals with a thickness of 3 mm are {{31}\\prime\\prime} and {{78}\\prime\\prime} , respectively, indicating excellent crystal quality. Hall measurements resulted in a charge carrier concentration of 1.5× {{10}18} cm-3, while exhibiting a mobility of 250 cm-2V-1 s-1. These values coincide with the values extracted from FTIR measurements and the lineshape fitting of the A1(LO)/plasmon coupled phonon mode of the confocal Raman measurements. SIMS investigations yielded a silicon atom concentration of 1.8× {{10}18} cm-3. This indicates an activation of the dopant atoms of approximately 90%. The TDD determined by CL dark spot counting was 2× {{10}6} cm-2. Within the measurement accuracy, the confocal Raman measurements did not show a tensile strain generation due to the silicon doping with resulting charge carrier concentrations of 1.5× {{10}18} cm-3.

  12. Large enhancements of thermopower and carrier mobility in quantum dot engineered bulk semiconductors.

    PubMed

    Liu, Yuanfeng; Sahoo, Pranati; Makongo, Julien P A; Zhou, Xiaoyuan; Kim, Sung-Joo; Chi, Hang; Uher, Ctirad; Pan, Xiaoqing; Poudeu, Pierre F P

    2013-05-22

    The thermopower (S) and electrical conductivity (σ) in conventional semiconductors are coupled adversely through the carriers' density (n) making it difficult to achieve meaningful simultaneous improvements in both electronic properties through doping and/or substitutional chemistry. Here, we demonstrate the effectiveness of coherently embedded full-Heusler (FH) quantum dots (QDs) in tailoring the density, mobility, and effective mass of charge carriers in the n-type Ti(0.1)Zr(0.9)NiSn half-Heusler matrix. We propose that the embedded FH QD forms a potential barrier at the interface with the matrix due to the offset of their conduction band minima. This potential barrier discriminates existing charge carriers from the conduction band of the matrix with respect to their relative energy leading to simultaneous large enhancements of the thermopower (up to 200%) and carrier mobility (up to 43%) of the resulting Ti(0.1)Zr(0.9)Ni(1+x)Sn nanocomposites. The improvement in S with increasing mole fraction of the FH-QDs arises from a drastic reduction (up to 250%) in the effective carrier density coupled with an increase in the carrier's effective mass (m*), whereas the surprising enhancement in the mobility (μ) is attributed to an increase in the carrier's relaxation time (τ). This strategy to manipulate the transport behavior of existing ensembles of charge carriers within a bulk semiconductor using QDs is very promising and could pave the way to a new generation of high figure of merit thermoelectric materials. PMID:23607819

  13. Large epitaxial bi-axial strain induces a Mott-like phase transition in VO{sub 2}

    SciTech Connect

    Kittiwatanakul, Salinporn; Wolf, Stuart A.; Lu, Jiwei

    2014-08-18

    The metal insulator transition (MIT) in vanadium dioxide (VO{sub 2}) has been an important topic for recent years. It has been generally agreed upon that the mechanism of the MIT in bulk VO{sub 2} is considered to be a collaborative Mott-Peierls transition, however, the effect of strain on the phase transition is much more complicated. In this study, the effect of the large strain on the properties of VO{sub 2} films was investigated. One remarkable result is that highly strained epitaxial VO{sub 2} thin films were rutile in the insulating state as well as in the metallic state. These highly strained VO{sub 2} films underwent an electronic phase transition without the concomitant Peierls transition. Our results also show that a very large tensile strain along the c-axis of rutile VO{sub 2} resulted in a phase transition temperature of ∼433 K, much higher than in any previous report. Our findings elicit that the metal insulator transition in VO{sub 2} can be driven by an electronic transition alone, rather the typical coupled electronic-structural transition.

  14. Analytical model for quantization on strained and unstrained bulk nMOSFET and its impact on quasi-ballistic current

    NASA Astrophysics Data System (ADS)

    Ferrier, M.; Clerc, R.; Ghibaudo, G.; Boeuf, F.; Skotnicki, T.

    2006-01-01

    This work presents a fully analytical model for the evaluation of quasi-ballistic transport in advanced bulk nMOS devices. Starting from the Lundstrom approach, an original analytical evaluation of energy levels advantageously replaces numerical time-consuming Poisson-Schrödinger simulations or usual analytical single subband approximations. This model allows an accurate estimation of quantum mechanical effects and their impact on quasi-ballistic performances. Based on an improved Airy method, it accounts for the non-linearity of the depletion potential, the wave function oxide penetration and a generalized concept of effective field. As it relies on subband structure, it can easily be extended to biaxially strained devices provided that the band modifications are known. Interest of strained channels is confirmed even on the base of ballistic or quasi-ballistic hypothesis. This model has been used for the evaluation of the "ballisticity" along the ITRS roadmap, showing for next generation devices a quasi-ballistic current slightly higher than that predicted with the usual drift diffusion and saturation velocity equations. However, as already reported, MOS devices still operate far from their ballistic limit down to HP45 nm node.

  15. Mapping strain fields induced in Zr-based bulk metallic glasses during in-situ nanoindentation by X-ray nanodiffraction

    NASA Astrophysics Data System (ADS)

    Gamcová, J.; Mohanty, G.; Michalik, Š.; Wehrs, J.; Bednarčík, J.; Krywka, C.; Breguet, J. M.; Michler, J.; Franz, H.

    2016-01-01

    A pioneer in-situ synchrotron X-ray nanodiffraction approach for characterization and visualization of strain fields induced by nanoindentation in amorphous materials is introduced. In-situ nanoindentation experiments were performed in transmission mode using a monochromatic and highly focused sub-micron X-ray beam on 40 μm thick Zr-based bulk metallic glass under two loading conditions. Spatially resolved X-ray diffraction scans in the deformed volume of Zr-based bulk metallic glass covering an area of 40 × 40 μm2 beneath the pyramidal indenter revealed two-dimensional map of elastic strains. The largest value of compressive elastic strain calculated from diffraction data at 1 N load was -0.65%. The region of high elastic compressive strains (<-0.3%) is located beneath the indenter tip and has radius of 7 μm.

  16. Stabilization of laser-induced plasma in bulk water using large focusing angle

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Xue, Boyang; Song, Jiaojian; Lu, Yuan; Zheng, Ronger

    2016-08-01

    Laser focusing geometry effects on plasma emissions in bulk water were investigated with five focusing angles ranging from 11.9° to 35.4°. Fast imaging and space-resolved spectroscopy techniques were used to observe the plasma emission distributions and fluctuations. We demonstrated that by increasing the focusing angle, discrete and irregular plasma formed in multiple sites could be turned into continuous and stable plasma with single core fixed at the laser focal point. This indicates the key role of laser focusing angle in the stabilization of plasma positions, which is crucial to the improvement of laser-induced breakdown spectroscopy repeatability in bulk water.

  17. Large-strain quasi-static compression materials tests in support of penetration modeling research

    SciTech Connect

    Brandon, S.L.; Totten, J.J.

    1990-09-01

    Target penetration by projectiles typically generates large strains, at least locally. Hence, accurate analytic modeling of penetration demands that constitutive models be calibrated using large strain material test data. Tensile test data is limited by specimen necking (the Considere criterion), restricting attainable strains. Linear extrapolation of tensile data to target strains can seriously overestimate the material flow stress, resulting in erroneously stiff analytical predictions. That is, other tests which can attain larger strains often reveal a continually decreasing tangent modulus at large strains. We report quasistatic room temperature compression tests approaching true strains of {var epsilon} = {minus}1. A few tensile tests are included to illustrate the previous point. Materials tested are 7075-T651, 5083-H131, and 6061-T651 aluminum alloys, 4340 steel and X21-C tungsten alloy. 7 refs., 6 figs.

  18. A novel Ho 36Dy 20Al 24Co 20 bulk metallic glass with large magnetocaloric effect

    NASA Astrophysics Data System (ADS)

    Liang, L.; Hui, X.; Zhang, C. M.; Lu, Z. P.; Chen, G. L.

    2008-04-01

    A new heavy rare-earth-based Ho 36Dy 20Al 24Co 20 bulk metallic glass (BMG) has been prepared by a copper mold casting. A maximum magnetic entropy change of 11.77 J/kg K has been measured in Ho 36Dy 20Al 24Co 20 bulk metallic glass under a magnetic field of 5 Tesla, which is larger than that of the early reported Ho-based bulk metallic glass Ho 30Y 26Al 24Co 20. The half-maximum temperature range of the entropy change peak is as large as 40 K, leading to a superior refrigerant capacity to those of the Gd 5Si 2Ge 2 and Gd 5Si 2Ge 1.9Fe 0.1 crystalline compounds. The excellent magnetocaloric effect together with the unique properties of metallic glass makes this alloy a promising candidate for a magnetic refrigerant in the temperature range below 50 K.

  19. Comparative genome analysis of a large Dutch Legionella pneumophila strain collection identifies five markers highly correlated with clinical strains

    PubMed Central

    2010-01-01

    Background Discrimination between clinical and environmental strains within many bacterial species is currently underexplored. Genomic analyses have clearly shown the enormous variability in genome composition between different strains of a bacterial species. In this study we have used Legionella pneumophila, the causative agent of Legionnaire's disease, to search for genomic markers related to pathogenicity. During a large surveillance study in The Netherlands well-characterized patient-derived strains and environmental strains were collected. We have used a mixed-genome microarray to perform comparative-genome analysis of 257 strains from this collection. Results Microarray analysis indicated that 480 DNA markers (out of in total 3360 markers) showed clear variation in presence between individual strains and these were therefore selected for further analysis. Unsupervised statistical analysis of these markers showed the enormous genomic variation within the species but did not show any correlation with a pathogenic phenotype. We therefore used supervised statistical analysis to identify discriminating markers. Genetic programming was used both to identify predictive markers and to define their interrelationships. A model consisting of five markers was developed that together correctly predicted 100% of the clinical strains and 69% of the environmental strains. Conclusions A novel approach for identifying predictive markers enabling discrimination between clinical and environmental isolates of L. pneumophila is presented. Out of over 3000 possible markers, five were selected that together enabled correct prediction of all the clinical strains included in this study. This novel approach for identifying predictive markers can be applied to all bacterial species, allowing for better discrimination between strains well equipped to cause human disease and relatively harmless strains. PMID:20630115

  20. Retaining Large and Adjustable Elastic Strains of Kilogram-Scale Nb Nanowires.

    PubMed

    Hao, Shijie; Cui, Lishan; Wang, Hua; Jiang, Daqiang; Liu, Yinong; Yan, Jiaqiang; Ren, Yang; Han, Xiaodong; Brown, Dennis E; Li, Ju

    2016-02-10

    Individual metallic nanowires can sustain ultralarge elastic strains of 4-7%. However, achieving and retaining elastic strains of such magnitude in kilogram-scale nanowires are challenging. Here, we find that under active load, ∼ 5.6% elastic strain can be achieved in Nb nanowires embedded in a metallic matrix deforming by detwinning. Moreover, large tensile (2.8%) and compressive (-2.4%) elastic strains can be retained in kilogram-scale Nb nanowires when the external load was fully removed, and adjustable in magnitude by processing control. It is then demonstrated that the retained tensile elastic strains of Nb nanowires can increase their superconducting transition temperature and critical magnetic field, in comparison with the unstrained original material. This study opens new avenues for retaining large and tunable elastic strains in great quantities of nanowires and elastic-strain-engineering at industrial scale. PMID:26745016

  1. Determining meteoroid bulk densities using a plasma scattering model with high-power large-aperture radar data

    NASA Astrophysics Data System (ADS)

    Close, Sigrid; Volz, Ryan; Loveland, Rohan; Macdonell, Alex; Colestock, Patrick; Linscott, Ivan; Oppenheim, Meers

    2012-09-01

    We present an improved technique for calculating bulk densities of low-mass (<1 g) meteoroids using a scattering model applied to the high-density plasma formed around the meteoroid as it enters Earth’s atmosphere. These plasmas, referred to as head echoes, travel at or near the speed of the meteoroid, thereby allowing the determination of the ballistic coefficient (mass divided by physical cross-section), which depends upon speed and deceleration. Concurrently, we apply a scattering model to the returned signal strength of the head echo in order to correlate radar-cross-section (RCS) to plasma density and meteoroid mass. In this way, we can uniquely solve for the meteoroid mass, radius and bulk density independently. We have applied this new technique to head echo data collected in 2007 and 2008 simultaneously at VHF (160 MHz) and UHF (422 MHz) at ALTAIR, which is a high-power large-aperture radar located on the Kwajalein Atoll. These data include approximately 20,000 detections with dual-frequency, dual-polarization, and monopulse (i.e. angle) returns. From 2000 detections with the smallest monopulse errors, we find a mean meteoroid bulk density of 0.9 g/cm3 with observations spanning almost three orders of magnitude from 0.01 g/cm3 to 8 g/cm3. Our results show a clear dependence between meteoroid bulk density and altitude of head echo formation, as well as dependence between meteoroid bulk density and 3D speed. The highest bulk densities are detected at the lowest altitudes and lowest speeds. Additionally, we stipulate that the approximations used to derive the ballistic parameter, in addition to neglecting fragmentation, suggest that the traditional ballistic parameter must be used with caution when determining meteoroid parameters.

  2. Characterizing chaotic dynamics from simulations of large strain behavior of a granular material under biaxial compression

    NASA Astrophysics Data System (ADS)

    Small, Michael; Walker, David M.; Tordesillas, Antoinette; Tse, Chi K.

    2013-03-01

    For a given observed time series, it is still a rather difficult problem to provide a useful and compelling description of the underlying dynamics. The approach we take here, and the general philosophy adopted elsewhere, is to reconstruct the (assumed) attractor from the observed time series. From this attractor, we then use a black-box modelling algorithm to estimate the underlying evolution operator. We assume that what cannot be modeled by this algorithm is best treated as a combination of dynamic and observational noise. As a final step, we apply an ensemble of techniques to quantify the dynamics described in each model and show that certain types of dynamics provide a better match to the original data. Using this approach, we not only build a model but also verify the performance of that model. The methodology is applied to simulations of a granular assembly under compression. In particular, we choose a single time series recording of bulk measurements of the stress ratio in a biaxial compression test of a densely packed granular assembly—observed during the large strain or so-called critical state regime in the presence of a fully developed shear band. We show that the observed behavior may best be modeled by structures capable of exhibiting (hyper-) chaotic dynamics.

  3. Strain localization in usnaturated soils with large deformation

    NASA Astrophysics Data System (ADS)

    Song, X.; Borja, R. I.

    2014-12-01

    Strain localization is a ubiquitous feature of granular materials undergoing nonhomogeneous deformation. In unsaturated porous media, how the localized deformation band is formed depends crucially on the degree of saturation, since fluid in the pores of a solid imposes a volume constraint on the deformation of the solid. When fluid flow is involved, the inception of the localized deformation band also depends on the heterogeneity of a material, which is quantified in terms of the spatial variation of density, the degree of saturation, and matric suction. We present a mathematical framework for coupled solid-deformation/fluid-diffusion in unsaturated porous media that takes into account material and geometric nonlinearities [1, 2]. The framework relies on the continuum principle of thermodynamics to identify an effective, or constitutive, stress for the solid matrix, and a water retention law that highlights the interdependence of degree of saturation, suction, and porosity of the material. We discuss the role of heterogeneity, quantified either deterministically or stochastically, on the development of a persistent shear band. We derive bifurcation conditions [3] governing the initiation of such a shear band. This research is inspired by current testing techniques that allow nondestructive and non-invasive measurement of density and the degree of saturation through high-resolution imaging [4]. The numerical simulations under plane strain condition demonstrate that the bifurcation not only manifests itself on the loading response curve and but also in the space of the degree of saturation, specific volume and suction stress. References[1] Song X, Borja RI, Mathematical framework for unsaturated flow in the finite deformation range. Int. J. Numer. Meth. Engng 2014; 97: 658-686. [2] Song X, Borja RI, Finite deformation and fluid flow in unsaturated soils with random heterogeneity. Vadose Zone Journal 2014; doi:10.2136/vzj2013.07.0131. [3] Song X, Borja RI, Instability

  4. Large strain under a low electric field in lead-free bismuth-based piezoelectrics

    NASA Astrophysics Data System (ADS)

    Ullah, Aman; Won Ahn, Chang; Ullah, Amir; Won Kim, Ill

    2013-07-01

    In this letter, the composition and electric field dependent strain behavior of (1 - x)Bi0.5(Na0.78K0.22)0.5TiO3-xBi(Mg0.5Ti0.5)O3 (BNKT-BMT) were investigated to develop lead-free piezoelectric materials with a large strain response at a low driving field for actuator applications. A large strain of 0.35% (Smax/Emax = 636 pm/V) at an applied field of 55 kV/cm was obtained with a composition of 4 mol. % BMT. In particular, the electric field required to deliver large strains was reduced to a level that revealed not only a large Smax/Emax of 542 pm/V at a driving field as low as 35 kV/cm, but also remarkably suppressed the large hysteresis.

  5. Large tunability of lattice thermal conductivity of monolayer silicene via mechanical strain

    NASA Astrophysics Data System (ADS)

    Xie, Han; Ouyang, Tao; Germaneau, Éric; Qin, Guangzhao; Hu, Ming; Bao, Hua

    2016-02-01

    Strain engineering is one of the most promising and effective routes toward continuously tuning the electronic and optic properties of materials, while thermal properties are generally believed to be insensitive to mechanical strain. In this paper, the strain-dependent thermal conductivity of monolayer silicene under uniform biaxial tension is computed by solving the phonon Boltzmann transport equation with interatomic force constants extracted from first-principles calculations. Unlike the commonly believed understanding that thermal conductivity only slightly decreases with increased tensile strain for bulk materials, it is found that the thermal conductivity of silicene can increase dramatically with strain. Depending on the size, the maximum thermal conductivity of strained silicene can be a few times higher than that of the unstrained case. Such an unusual strain dependence is mainly attributed to the dramatic enhancement in the acoustic phonon lifetime. Such enhancement plausibly originates from the flattening of the buckling of the silicene structure upon stretching, which is unique for silicene as compared with other common two-dimensional materials. Our findings offer perspectives on modulating the thermal properties of low-dimensional structures for applications such as thermoelectrics, thermal circuits, and nanoelectronics.

  6. Bistable electroactive polymers (BSEP): large-strain actuation of rigid polymers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin; Niu, Xiaofan; Brochu, Paul; Yuan, Wei; Li, Huafeng; Chen, Bin; Pei, Qibing

    2010-04-01

    Reversible, large-strain, bistable actuation has been a lasting puzzle in the pursuit of smart materials and structures. Conducting polymers are bistable, but the achievable strain is small. Large deformations have been achieved in dielectric elastomers at the expense of mechanical strength. The gel or gel-like soft polymers generally have elastic moduli around or less than 10 MPa. The deformed polymer relaxes to its original shape once the applied electric field is removed. We report new, bistable electroactive polymers (BSEP) that are capable of electrically actuated strains as high as 335% area strain. The BSEP could be useful for constructing rigid structures. The structures can support high mechanical loads, and be actuated to large-strain deformations. We will present one unique application of the BSEP for Braille displays that can be quickly refreshed and maintain the displayed contents without a bias voltage.

  7. Characterization of the Bauschinger effect in sheet metal undergoing large strain reversals in bending

    NASA Astrophysics Data System (ADS)

    Hanzon, Drew Wyatt

    This work consists on the quantification of sheet metal uniaxial stress-strain reversals from pure bending tests. Bending strains to approximately 10% were measured by strain gages and interferometry. Bending-unbending moments and strains were modeled and compared closely to the experimental data. The reverse uniaxial stress-strains curves were determined from the optimal fit of the model. Bauschinger effects were described by the reverse uniaxial response at the elasto-plastic range, between the elastic and the large strain, power fit ranges. Arc and straight line fittings on the lnsigma-lnepsilon scale proved accurate to describe the elasto-plastic behavior. Reverse uniaxial data determined for DP590 and DP780 steels and two Aluminum alloys showed significant Bauschinger effects with distinct features. For the DP steels the magnitudes of the reverse compressive sigma-epsilon curves compared moderately higher, and merging to a power curve with parameters K, n previously defined by tension testing. Bauschinger effects at small reversed strains were less pronounced for the aluminum alloys. However, at higher strains the reverse elasto-plastic response softened considerably, and during the unbending span the magnitudes of the reverse compressive strains remained below the corresponding K, n tensile values. The results showed pure bending as an efficient, simple to use technique to generate sigma-epsilon data for sheet metal at large reverse strains without the complicating restraining hardware required by direct compression methods.

  8. Transparent large-strain thermoplastic polyurethane magnetoactive nanocomposites.

    PubMed

    Yoonessi, Mitra; Peck, John A; Bail, Justin L; Rogers, Richard B; Lerch, Bradley A; Meador, Michael A

    2011-07-01

    Organically modified superparamagnetic MnFe(2)O(4)/thermoplastic polyurethane elastomer (TPU) nanocomposites (0.1-8 wt %) were prepared by solvent mixing followed by solution casting. Linear aliphatic alkyl chain modification of spherical MnFe(2)O(4) provided compatibility with the TPU containing a butanediol extended polyester polyol-MDI. All MnFe(2)O(4)/TPU nanocomposite films were superparamagnetic and their saturation magnetization, σ(s), increased with increasing MnFe(2)O(4) content. All nanocomposite films exhibited large deformations (>10 mm) under a magneto-static field. This is the first report of large actuation of magnetic nanoparticle nanocomposites at low-loading levels of 0.1 wt % (0.025 vol %). The maximum actuation deformation of the MnFe(2)O(4)/TPU nanocomposite films increased exponentially with increasing nanoparticle concentration. An empirical correlation between the maximum displacement, saturation magnetization, and magnetic nanoparticle loading is proposed. The cyclic deformation actuation of a 6 wt % surface modified MnFe(2)O(4)/TPU, in a low magnetic field 151 < B(y) < 303 Oe, exhibited excellent reproducibility and controllability. MnFe(2)O(4)/TPU nanocomposite films (0.1-2 wt %) were transparent and semitransparent over the wavelengths from 350 to 700 nm. PMID:21710967

  9. Large-Strain Time-Temperature Equivalence and Adiabatic Heating of Polyethylene

    SciTech Connect

    Furmanski, Jevan; Brown, Eric; Cady, Carl M.

    2012-06-06

    Time-temperature equivalence is a well-known phenomenon in time-dependent material response, where rapid events at a moderate temperature are indistinguishable from some occurring at modest rates but elevated temperatures. However, there is as-yet little elucidation of how well this equivalence holds for substantial plastic strains. In this work, we demonstrate time-temperature equivalence over a large range in a previously studied high-density polyethylene formulation (HDPE). At strain-rates exceeding 0.1/s, adiabatic heating confounds the comparison of nominally isothermal material response, apparently violating time-temperature equivalence. Strain-rate jumps can be employed to access the instantaneous true strain rate without heating. Adiabatic heating effects were isolated by comparing a locus of isothermal instantaneous flow stress measurements from strain-rate jumps up to 1/s with the predicted equivalent states at 0.01/s and 0.001/s in compression. Excellent agreement between the isothermal jump condition locus and the quasi-static tests was observed up to 50% strain, yielding one effective isothermal plastic response for each material for a given time-temperature equivalent state. These results imply that time-temperature equivalence can be effectively used to predict the deformation response of polymers during extreme mechanical events (large strain and high strain-rate) from measurements taken at reduced temperatures and nominal strain-rates in the laboratory.

  10. Large strain dynamic compression for soft materials using a direct impact experiment

    NASA Astrophysics Data System (ADS)

    Meenken, T.; Hiermaier, S.

    2006-08-01

    Measurement of strain rate dependent material data of low density low strength materials like polymeric foams and rubbers still poses challenges of a different kind to the experimental set up. For instance, in conventional Split Hopkinson Pressure Bar tests the impedance mismatch between the bars and the specimen makes strain measurement almost impossible. Application of viscoelastic bars poses new problems with wave dispersion. Also, maximum achievable strains and strain rates depend directly on the bar lengths, resulting in large experimental set ups in order to measure relevant data for automobile crash applications. In this paper a modified SHPB will be presented for testing low impedance materials. High strains can be achieved with nearly constant strain rate. A thin film stress measurement has been applied to the specimen/bar interfaces to investigate the initial sample ring up process. The process of stress homogeneity within the sample was investigated on EPDM and PU rubber.

  11. A simple multi-seeding approach to growth of large YBCO bulk with a diameter above 53 mm

    NASA Astrophysics Data System (ADS)

    Tang, Tian-wei; Wu, Dong-jie; Wu, Xing-da; Xu, Ke-Xi

    2015-12-01

    A successful simple multi-seeding approach to growing large size Y-Ba-C-O (YBCO) bulks is reported. Compared with the common single seeding method, our multi-seeding method is more efficient. By using four SmBa2Cu3O7-δ (Sm-123) seeds cut from a large size Sm-Ba-C-O (SmBCO) single domain, large YBCO samples up to 53 mm in diameter could be produced successfully and 100 mm diameter samples can also be grown. Experimental results show that the processing time can be shortened greatly by using this new approach, and the superconducting properties can also be improved. The Hall probe mapping shows that the trapped field distribution of 53 mm diameter multi-seeded sample is homogeneous and the peak value is up to 0.53 T. The magnetic levitation force density reaches to 14.7 N/cm2 (77 K, 0.5 T).

  12. Determination of bulk properties of tropical cloud clusters from large scale heat and moisture budgets, appendix B

    NASA Technical Reports Server (NTRS)

    Yanai, M.; Esbensen, S.; Chu, J.

    1972-01-01

    The bulk properties of tropical cloud clusters, as the vertical mass flux, the excess temperature, and moisture and the liquid water content of the clouds, are determined from a combination of the observed large-scale heat and moisture budgets over an area covering the cloud cluster, and a model of a cumulus ensemble which exchanges mass, heat, vapor and liquid water with the environment through entrainment and detrainment. The method also provides an understanding of how the environmental air is heated and moistened by the cumulus convection. An estimate of the average cloud cluster properties and the heat and moisture balance of the environment, obtained from 1956 Marshall Islands data, is presented.

  13. Modelling Deformation and Texture Evolution in OFHC Copper at Large Strain and High Strain Rate

    NASA Astrophysics Data System (ADS)

    Bonora, Nicola; Testa, Gabriel; Ruggiero, Andrew; Iannitti, Gianluca; Hörnqvist, Magnus; Mortazavi, Nooshin

    2015-06-01

    In this work, a two-scale approach to simulate high rate deformation and texture evolution in OFHC copper is presented. The modified Rusinek-Klepaczko material model was used to simulate the response of the material at continuum scale accounting for different deformation mechanisms occurring over an extensive range of strain rate and temperature. Material model parameters were determined from characterization test (mainly uniaxial tests) results. Successively, the model was validated simulating material deformation in Taylor anvil impact, symmetric Taylor impact (rod-on-rod) and dynamic tensile extrusion (DTE) tests. Texture evolution, under different deformation paths was simulated using the crystal plasticity package CPFEM and results were compared with those obtained by EBSD analysis. The possibility to incorporate the effect of grain size evolution and fragmentation at continuum scale is discussed.

  14. Retaining large and adjustable elastic strains of kilogram-scale Nb nanowires [Better Superconductor by Elastic Strain Engineering: Kilogram-scale Free-Standing Niobium Metal Composite with Large Retained Elastic Strains

    DOE PAGESBeta

    Hao, Shijie; Cui, Lishan; Wang, Hua; Jiang, Daqiang; Liu, Yinong; Yan, Jiaqiang; Ren, Yang; Han, Xiaodong; Brown, Dennis E.; Li, Ju

    2016-02-10

    Crystals held at ultrahigh elastic strains and stresses may exhibit exceptional physical and chemical properties. Individual metallic nanowires can sustain ultra-large elastic strains of 4-7%. However, retaining elastic strains of such magnitude in kilogram-scale nanowires is challenging. Here, we find that under active load, ~5.6% elastic strain can be achieved in Nb nanowires in a composite material. Moreover, large tensile (2.8%) and compressive (-2.4%) elastic strains can be retained in kilogram-scale Nb nanowires when the composite is unloaded to a free-standing condition. It is then demonstrated that the retained tensile elastic strains of Nb nanowires significantly increase their superconducting transitionmore » temperature and critical magnetic fields, corroborating ab initio calculations based on BCS theory. This free-standing nanocomposite design paradigm opens new avenues for retaining ultra-large elastic strains in great quantities of nanowires and elastic-strain-engineering at industrial scale.« less

  15. Simultaneous Large Enhancements in Thermopower and Electrical Conductivity of Bulk Nanostructured Half-Heusler Alloys

    SciTech Connect

    Makongo, Julien P. A.; Misra, Dinesh K.; Zhou, Xiaoyuan; Pant, Aditya; Shabetai, Michael R.; Su, Xianli; Uher, Ctirad; Stokes, Kevin L.; Poudeu, Pierre F. P.

    2011-10-04

    Large reductions in the thermal conductivity of thermoelectrics using nanostructures have been widely demonstrated. Some enhancements in the thermopower through nanostructuring have also been reported. However, these improvements are generally offset by large drops in the electrical conductivity due to a drastic reduction in the mobility. Here, we show that large enhancements in the thermopower and electrical conductivity of half-Heusler (HH) phases can be achieved simultaneously at high temperatures through coherent insertion of nanometer scale full-Heusler (FH) inclusions within the matrix. The enhancements in the thermopower of the HH/FH nanocomposites arise from drastic reductions in the “effective” carrier concentration around 300 K. Surprisingly, the mobility increases drastically, which compensates for the decrease in the carrier concentration and minimizes the drop in the electrical conductivity. Interestingly, the carrier concentration in HH/FH nanocomposites increases rapidly with temperature, matching that of the HH matrix at high temperatures, whereas the temperature dependence of the mobility significantly deviates from the typical T–α law and slowly decreases (linearly) with rising temperature. This remarkable interplay between the temperature dependence of the carrier concentration and mobility in the nanocomposites results in large increases in the power factor at 775 K. In addition, the embedded FH nanostructures also induce moderate reductions in the thermal conductivity leading to drastic increases in the ZT of HH(1 – x)/FH(x) nanocomposites at 775 K. By combining transmission electron microscopy and charge transport data, we propose a possible charge carrier scattering mechanism at the HH/FH interfaces leading to the observed anomalous electronic transport in the synthesized HH(1 – x)/FH(x) nanocomposites.

  16. FeCoSiBNbCu bulk metallic glass with large compressive deformability studied by time-resolved synchrotron X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Stoica, Mihai; Scudino, Sergio; Bednarčik, Jozef; Kaban, Ivan; Eckert, Jürgen

    2014-02-01

    By adding 0.5 at. % Cu to the strong but brittle [(Fe0.5Co0.5)0.75Si0.05B0.20]96Nb4 bulk metallic glass, fully amorphous rods with diameters up to 2 mm were obtained. The monolithic samples with 1 mm diameter revealed a fracture strain of 3.80% and a maximum stress of 4143 MPa upon compression, together with a slight work-hardening behavior. SEM micrographs of fractured samples did neither reveal any shear bands on the lateral surface nor the typical vein patterns which characterize ductile fracture. However, some layers appear to have flowed and this phenomenon took place before the brittle final fracture. An estimate of the temperature rise ΔT in the shear plane gives 1039 K, which is large enough to melt a layer of 120 nm. The overall performance and the macroscopic plastic strain depend on the interaction between cleavage-like and viscous flow-like features. Mechanical tests performed in-situ under synchrotron radiation allowed the calculation of the strain tensor components, using the reciprocal-space data and analyzing the shift of the first (the main) and the second broad peak positions in the X-ray diffraction patterns. The results revealed that each atomic shell may have a different stiffness, which may explain the macroscopic compressive plastic deformation. Also, there were no signs of (nano) crystallization induced by the applied stress, but the samples preserve a monolithic amorphous structure until catastrophic failure occurs.

  17. FeCoSiBNbCu bulk metallic glass with large compressive deformability studied by time-resolved synchrotron X-ray diffraction

    SciTech Connect

    Stoica, Mihai Scudino, Sergio; Bednarčik, Jozef; Kaban, Ivan; Eckert, Jürgen

    2014-02-07

    By adding 0.5 at. % Cu to the strong but brittle [(Fe{sub 0.5}Co{sub 0.5}){sub 0.75}Si{sub 0.05}B{sub 0.20}]{sub 96}Nb{sub 4} bulk metallic glass, fully amorphous rods with diameters up to 2 mm were obtained. The monolithic samples with 1 mm diameter revealed a fracture strain of 3.80% and a maximum stress of 4143 MPa upon compression, together with a slight work-hardening behavior. SEM micrographs of fractured samples did neither reveal any shear bands on the lateral surface nor the typical vein patterns which characterize ductile fracture. However, some layers appear to have flowed and this phenomenon took place before the brittle final fracture. An estimate of the temperature rise ΔT in the shear plane gives 1039 K, which is large enough to melt a layer of 120 nm. The overall performance and the macroscopic plastic strain depend on the interaction between cleavage-like and viscous flow-like features. Mechanical tests performed in-situ under synchrotron radiation allowed the calculation of the strain tensor components, using the reciprocal-space data and analyzing the shift of the first (the main) and the second broad peak positions in the X-ray diffraction patterns. The results revealed that each atomic shell may have a different stiffness, which may explain the macroscopic compressive plastic deformation. Also, there were no signs of (nano) crystallization induced by the applied stress, but the samples preserve a monolithic amorphous structure until catastrophic failure occurs.

  18. Structure/property development in aPET during large strain, solid phase polymer processing

    NASA Astrophysics Data System (ADS)

    Martin, Peter; Mohamed, Raja Roslan Raja

    2015-12-01

    Amorphous Polyethylene terephthalate (aPET) is increasingly of interest for the polymer packaging industry due to its blend of excellent mechanical properties and most importantly its ease of recyclability. Among the major commercial polymers it is almost unique in the degree of improvement in mechanical properties that can be obtained through process-induced strain. For many years these unique properties have been very successfully exploited in the injection stretch blow molding process, where it is deliberately stretched to very large strains using extremely high pressures. However, the material is now also being used in much lower pressure processes such as thermoforming where its properties are often not fully exploited. In this work the change in structure and properties of aPET with strain is systematically investigated using a high speed biaxial stretching machine. The aim was to demonstrate how the properties of the material could be controlled by large strain, high temperature biaxial stretching processes such as thermoforming and blow molding. The results show that property changes in the material are driven by orientation and the onset of rapid strain hardening at large strains. This in turn is shown to vary strongly with process-induced parameters such as the strain rate and the mode and magnitude of biaxial deformation.

  19. Processing of high performance (LRE)-Ba Cu O large, single-grain bulk superconductors in air

    NASA Astrophysics Data System (ADS)

    Hari Babu, N.; Iida, K.; Shi, Y.; Cardwell, D. A.

    2006-10-01

    We report the fabrication of large (LRE)BCO single-grains with improved superconducting properties for LRE = Nd, Sm and Gd using a practical process via both conventional top seeded melt growth (TSMG) and seeded infiltration-growth (SIG). This process uses a new generic seed crystal that promotes heterogeneous grain nucleation in the required orientation and suppresses the formation of solid solution in a controlled manner within individual grains by the addition of excess BaO2 to the precursor powder. The spatial distribution of the superconducting properties of LRE bulk superconductors as a function of BaO2 addition for large (LRE)BCO grains fabricated in air by TSMG and SIG for LRE = Gd, Sm and Nd are compared. The optimum BaO2 content required to fabricate single-grain (LRE)BCO with high and homogeneous Tc is determined from these experiments for each LRE system. The irreversibility fields of (LRE)BCO bulk superconductors processed in air are as high as those processed in reduced PO2. Critical current densities in excess of 105 A/cm2 at 77 K and higher trapped fields have been achieved in optimized (LRE)BCO superconductors fabricated in air for the first time.

  20. Synthesis and properties of ferromagnetic Fe-based (Fe, Ni, Co)-Mo-P-C-B bulk metallic glasses with large supercooled liquid region

    NASA Astrophysics Data System (ADS)

    Jia, Xingjie; Li, Yanhui; Wang, Hao; Xie, Guoqiang; Yamaura, Shinichi; Zhang, Wei

    2015-11-01

    New ferromagnetic Fe-based (Fe, Co, Ni)67.5Mo7.5P10C10B5 bulk metallic glasses have been developed based on an Fe75P10C10B5 alloy. These alloys exhibit large supercooled liquid region of 97-102 K, low glass transition temperature of 727-738 K, high glass-forming ability (GFA) with critical sample diameters of 3-4 mm, and low viscosity values on the order of 107 Pa s in the supercooled liquid state. The magnetic and mechanical measurements reveal that the alloys also possess good soft magnetic and mechanical properties, i.e., low coercive force of 3.04-4.37 A/m, rather high saturation magnetization of 0.77-0.83 T, high yield strength of 3344-3463 MPa, and large plastic strain of 0.6-1.1%. In addition, the effects of Mo, Co and Ni addition on the stabilization of supercooled liquid and GFA in the Fe-P-C-B alloy system have been discussed.

  1. Influence of large strain rheology on the peeling performances of Pressure Sensitive Adhesives

    NASA Astrophysics Data System (ADS)

    Villey, Richard; Ciccotti, Matteo; Creton, Costantino; Cortet, Pierre-Philippe; Yarusso, David J.

    2015-03-01

    The dependence of adhesion energy of Pressure Sensitive Adhesives (PSA) on peeling velocity reduces to a master curve using a time-temperature superposition principle, usually verified by the linear rheology of polymers. This result has guided models predicting peeling energy of PSA to consider the small strain rheology of the glue only, despite it can experience very large strains before debonding. The argument of the time-temperature superposition principle can actually also be applied to large strains and is thus not a stringent one. To clarify the role of large strain rheology during the peeling of PSA, we present experiments on commercial and custom-made tapes supplied by 3M Company. Small and large strain rheology differences are obtained by changing the glass transition temperature, the cross-linking density and the density of entanglements, yet remaining close to commercial PSA. The rheology influence is decoupled from geometrical effects, by examining the nontrivial dependence of the adhesion energy on the peeling angle. Finally, adhesion energy measurements and visualizations of the process zone, over a large range of peeling velocities, are discussed, in the perspective of building a model for the adherence considering the complete rheology of the glue.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  3. Study of Etching Pits in a Large-grain Single Cell Bulk Niobium Cavity

    SciTech Connect

    Zhao, Xin; Ciovati, Gianluigi; Reece, Charles E.; Wu, Andy T.

    2009-11-01

    Performance of SRF cavities are limited by non-linear localized effects. The variation of local material characters between "hot" and "cold" spots is thus of intense interest. Such locations were identified in a BCP-etched large-grain single-cell cavity and removed for examination by high resolution electron microscopy (SEM), electron-back scattering diffraction microscopy (EBSD), optical microscopy, and 3D profilometry. Pits with clearly discernable crystal facets were observed in both "hotspot" and "coldspot" specimens. The pits were found in-grain, at bi-crystal boundaries, and on tri-crystal junctions. They are interpreted as etch pits induced by surface crystal defects (e.g. dislocations). All "coldspots" examined had qualitatively low density of etching pits or very shallow tri-crystal boundary junction. EBSD revealed crystal structure surrounding the pits via crystal phase orientation mapping, while 3D profilometry gave information on the depth and size of the pits. In addition, a survey of the samples by energy dispersive X-ray analysis (EDX) did not show any significant contamination of the samples surface.

  4. A large-eddy simulation study on statistical attributes of urban-like geometries relevant to parameterizing bulk aerodynamic characteristics

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaowei; Anderson, William

    2015-11-01

    The inherent spatial heterogeneity exhibited by real urban environments complicates a priori estimation of the roughness height needed to parameterize the inertial layer mean streamwise velocity. A large-eddy simulation study of turbulent flow over 3-D random urban-like topographies is conducted to explore the effects of surface geometry on bulk aerodynamic characterization. In a mean sense, we find that statistical attributes including surface height root mean square and skewness can adequately capture the spatial heterogeneities and randomness of real urban geometries. We find, however, that higher-order statistical moments have a negligible affect on aerodynamic drag (i.e. kurtosis may be omitted). The results enable exploration of applicability of some recently-proposed roughness parameterizations that are relevant to complex, urban-like roughness (including the model proposed by Flack and Schultz, 2010: J. Fluids Eng. 132, 041203-1). We evaluate empirical parameters needed in these models for the present urban-like cases. We find that two empirical parameters (relevant to height rms and skewness) can characterize the bulk aerodynamic roughness of topographies with statistical attributes comparable to dense urban environments. This work was supported by the Army Research Office, Atmospheric Sciences Program (PM: Dr. S. Collier) under Grant # W911NF-13-1-0474. Computational resources were provided by the Texas Advanced Computing Center at the University of Texas.

  5. A new RE + 011 TSIG method for the fabrication of high quality and large size single domain YBCO bulk superconductors

    NASA Astrophysics Data System (ADS)

    Yang, W. M.; Chen, L. P.; Wang, X. J.

    2016-02-01

    High quality single domain YBCO bulk superconductors, 20 mm in diameter, have been fabricated using a new top seeded infiltration and growth method (called the RE + 011 TSIG method), with a new solid phase (Y2O3 + xBaCuO2) instead of the conventional Y2BaCuO5 solid phase, x = 0, 0.5, 1.0, 1.2, 1.5, 1.8, 2.0, 2.5, 3.0. The effects of different BaCuO2 contents x on the growth morphology, microstructure, and levitation force have been investigated. The results show that the levitation force of the YBCO bulks first increases and then decreases with increasing x, and reaches maximum levitation forces of about 49.2 N (77 K, 0.5 T, with the traditional liquid phase of YBa2Cu3O y + 3 BaCuO2 + 2 CuO) and 47 N (77.3 K, 0.5 T, with the new liquid phase of Y2O3 + 10 BaCuO2 + 6 CuO) when x = 1.2, which is much higher than that of the samples fabricated with the conventional solid phases (23 N). The average Y2BaCuO5 particle size is about 1 μm, which is much smaller than the 3.4 μm in the samples prepared with the conventional Y2BaCuO5 solid phase; this means that the flux pinning force of the sample can be improved by using the new solid phase. Based on this method, single domain YBCO bulks 40 mm, 59 mm, and 93 mm in diameter have also been fabricated using the TSIG process with the new solid phases (Y2O3 + 1.2BaCuO2). These results indicate that the new TSIG process developed by our lab is a very important and practical method for the fabrication of low cost, large size, and high quality single domain REBCO bulk superconductors.

  6. Coherent piezoelectric strain transfer to thick epitaxial ferromagnetic films with large lattice mismatch.

    PubMed

    Kim, Jang-Yong; Yao, Lide; van Dijken, Sebastiaan

    2013-02-27

    Strain control of epitaxial films using piezoelectric substrates has recently attracted significant scientific interest. Despite its potential as a powerful test bed for strain-related physical phenomena and strain-driven electronic, magnetic, and optical technologies, detailed studies on the efficiency and uniformity of piezoelectric strain transfer are scarce. Here, we demonstrate that full and uniform piezoelectric strain transfer to epitaxial films is not limited to systems with small lattice mismatch or limited film thickness. Detailed transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements of 100 nm thick CoFe(2)O(4) and La(2/3)Sr(1/3)MnO(3) epitaxial films on piezoelectric 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) substrates (+4.3% and -3.8% lattice mismatch) indicate that misfit dislocations near the interface do not hamper the transfer of piezoelectric strain. Instead, the epitaxial magnetic oxide films and PMN-PT substrates are strained coherently and their lattice parameters change linearly as a function of applied electric field when their remnant growth-induced strain state is negligible. As a result, ferromagnetic properties such as the coercive field, saturation magnetization, and Curie temperature can be reversibly tuned by electrical means. The observation of efficient piezoelectric strain transfer in large-mismatch heteroepitaxial structures opens up new possibilities for the engineering of strain-controlled physical properties in a broad class of hybrid material systems. PMID:23370268

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

    PubMed Central

    Feng, Aihen; Chen, Daolun; Li, Cheng; Gu, Xijia

    2010-01-01

    We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor. PMID:22163621

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

    PubMed

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

    2015-08-20

    A Michelson-type large core optical fiber sensor has been developed, which is designed based on the optical carrier-based microwave interferometry technique, and fabricated by using two pieces of 200-μm diameter fused silica core fiber as two arms of the Michelson interferometer. The interference fringe pattern caused by the optical path difference of the two arms is interrogated in the microwave domain, where the fringe visibility of 40 dB has easily been obtained. The strain sensing at both room temperature and high temperatures has been demonstrated by using such a sensor. Experimental results show that this sensor has a linear response to the applied strain, and also has relatively low temperature-strain cross talk. The dopant-free quality of the fused silica fiber provides high possibility for the sensor to have promising strain sensing performance in a high temperature environment. PMID:26368751

  9. The role of fabric in the large strain compressive behavior of human trabecular bone.

    PubMed

    Charlebois, Mathieu; Pretterklieber, Michael; Zysset, Philippe K

    2010-12-01

    Osteoporosis-related vertebral body fractures involve large compressive strains of trabecular bone. The small strain mechanical properties of the trabecular bone such as the elastic modulus or ultimate strength can be estimated using the volume fraction and a second order fabric tensor, but it remains unclear if similar estimations may be extended to large strain properties. Accordingly, the aim of this work is to identify the role of volume fraction and especially fabric in the large strain compressive behavior of human trabecular bone from various anatomical locations. Trabecular bone biopsies were extracted from human T12 vertebrae (n=31), distal radii (n=43), femoral head (n=44), and calcanei (n=30), scanned using microcomputed tomography to quantify bone volume fraction (BV/TV) and the fabric tensor (M), and tested either in unconfined or confined compression up to very large strains (∼70%). The mechanical parameters of the resulting stress-strain curves were analyzed using regression models to examine the respective influence of BV/TV and fabric eigenvalues. The compressive stress-strain curves demonstrated linear elasticity, yielding with hardening up to an ultimate stress, softening toward a minimum stress, and a steady rehardening followed by a rapid densification. For the pooled experiments, the average minimum stress was 1.89 ± 1.77 MPa, while the corresponding mean strain was 7.15 ± 1.84%. The minimum stress showed a weaker dependence with fabric as the elastic modulus or ultimate strength. For the confined experiments, the stress at a logarithmic strain of 1.2 was 8.08 ± 7.91 MPa, and the dissipated energy density was 5.67 ± 4.42 MPa. The latter variable was strongly related to the volume fraction (R(2)=0.83) but the correlation improved only marginally with the inclusion of fabric (R(2)=0.84). The influence of fabric on the mechanical properties of human trabecular bone decreases with increasing strain, while the role of volume fraction remains

  10. Whole-genome mapping reveals a large chromosomal inversion on Iberian Brucella suis biovar 2 strains.

    PubMed

    Ferreira, Ana Cristina; Dias, Ricardo; de Sá, Maria Inácia Corrêa; Tenreiro, Rogério

    2016-08-30

    Optical mapping is a technology able to quickly generate high resolution ordered whole-genome restriction maps of bacteria, being a proven approach to search for diversity among bacterial isolates. In this work, optical whole-genome maps were used to compare closely-related Brucella suis biovar 2 strains. This biovar is the unique isolated in domestic pigs and wild boars in Portugal and Spain and most of the strains share specific molecular characteristics establishing an Iberian clonal lineage that can be differentiated from another lineage mainly isolated in several Central European countries. We performed the BamHI whole-genome optical maps of five B. suis biovar 2 field strains, isolated from wild boars in Portugal and Spain (three from the Iberian lineage and two from the Central European one) as well as of the reference strain B. suis biovar 2 ATCC 23445 (Central European lineage, Denmark). Each strain showed a distinct, highly individual configuration of 228-231 BamHI fragments. Nevertheless, a low divergence was globally observed in chromosome II (1.6%) relatively to chromosome I (2.4%). Optical mapping also disclosed genomic events associated with B. suis strains in chromosome I, namely one indel (3.5kb) and one large inversion (944kb). By using targeted-PCR in a set of 176 B. suis strains, including all biovars and haplotypes, the indel was found to be specific of the reference strain ATCC 23445 and the large inversion was shown to be an exclusive genomic marker of the Iberian clonal lineage of biovar 2. PMID:27527786

  11. Facile strain analysis of largely bending films by a surface-labelled grating method

    NASA Astrophysics Data System (ADS)

    Akamatsu, Norihisa; Tashiro, Wataru; Saito, Keisuke; Mamiya, Jun-Ichi; Kinoshita, Motoi; Ikeda, Tomiki; Takeya, Jun; Fujikawa, Shigenori; Priimagi, Arri; Shishido, Atsushi

    2014-06-01

    Mechanical properties of flexible films, for example surface strain of largely bending films, are key to design of stretchable electronic devices, wearable biointegrated devices, and soft microactuators/robots. However, existing methods are mainly based on strain-gauge measurements that require miniaturized array sensors, lead wires, and complicated calibrations. Here we introduce a facile method, based on surface-labelled gratings, for two-dimensional evaluation of surface strains in largely bending films. With this technique, we demonstrate that soft-matter mechanics can be distinct from the mechanics of hard materials. In particular, liquid-crystalline elastomers may undergo unconventional bending in three dimensions, in which both the inner and outer surfaces of the bending film are compressed. We also show that this method can be applied to amorphous elastomeric films, which highlights the general importance of this new mechanical evaluation tool in designing soft-matter-based electronic/photonic as well as biointegrated materials.

  12. Facile strain analysis of largely bending films by a surface-labelled grating method

    PubMed Central

    Akamatsu, Norihisa; Tashiro, Wataru; Saito, Keisuke; Mamiya, Jun-ichi; Kinoshita, Motoi; Ikeda, Tomiki; Takeya, Jun; Fujikawa, Shigenori; Priimagi, Arri; Shishido, Atsushi

    2014-01-01

    Mechanical properties of flexible films, for example surface strain of largely bending films, are key to design of stretchable electronic devices, wearable biointegrated devices, and soft microactuators/robots. However, existing methods are mainly based on strain-gauge measurements that require miniaturized array sensors, lead wires, and complicated calibrations. Here we introduce a facile method, based on surface-labelled gratings, for two-dimensional evaluation of surface strains in largely bending films. With this technique, we demonstrate that soft-matter mechanics can be distinct from the mechanics of hard materials. In particular, liquid-crystalline elastomers may undergo unconventional bending in three dimensions, in which both the inner and outer surfaces of the bending film are compressed. We also show that this method can be applied to amorphous elastomeric films, which highlights the general importance of this new mechanical evaluation tool in designing soft-matter-based electronic/photonic as well as biointegrated materials. PMID:24948462

  13. Stress-strain state simulation of large-sized cable-stayed shell structures

    NASA Astrophysics Data System (ADS)

    Ponomarev, S.; Zhukov, A.; Belkov, A.; Ponomarev, V.; Belov, S.; Pavlov, M.

    2015-12-01

    This paper studies the opportunities for applying framed cable-stayed shell structures to generate innovative structures in civil engineering. Numerical solution methods for stress-strain state problems of these kinds of geometrically nonlinear structures were developed. Developed methods efficiency is presented by a range of large-dimensional space antenna reflectors.

  14. Novel Ti-base superelastic alloys with large recovery strain and excellent biocompatibility.

    PubMed

    Fu, Jie; Yamamoto, Akiko; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-04-01

    In this study, a new Ti-Zr-Nb-Sn alloy system was developed as Ni-free biomedical superelastic alloys with a large recovery strain and excellent biocompatibility. Ti-18Zr-(9-16)Nb-(0-4)Sn alloys were prepared by an Ar arc melting method and the effect of composition on the crystal structure and superelastic properties was investigated. A large superelastic recovery strain of 6.0% was observed in Ti-18Zr-12.5Nb-2Sn, Ti-18Zr-11Nb-3Sn, and Ti-18Zr-9.5Nb-4Sn alloys subjected to cold-rolling and solution treatment. XRD results showed that the large recovery strain of Sn-added alloys is due to a combination effect of a large transformation strain and a strong recrystallization texture. The Ti-18Zr-11Nb-3Sn alloy exhibited excellent cyclic stability with an extremely narrow stress hysteresis about 20MPa. Cytocompatibility was also examined using three types of cell lines, murine fibroblast L929, human osteosarcoma SaOS-2, and human umbilical vein endothelial cell HUVEC and the results showed that the Ti-18Zr-11Nb-3Sn alloy exhibited larger cell covering ratios when compared with those of the Ti-50.5Ni alloy for all kinds of cells. PMID:25676584

  15. Dispersion-Corrected Density Functional Theory Investigations of Structural and Electronic Properties of Bulk MoS2: Effect of Uniaxial Strain

    NASA Astrophysics Data System (ADS)

    Nguyen, Chuong V.; Hieu, Nguyen N.; Nguyen, Duong T.

    2015-11-01

    Strain-dependent structural and electronic properties of MoS2 materials are investigated using first principles calculations. The structural and electronic band structures of the MoS2 with relaxed unit cells are optimized and calculated by the dispersion-corrected density functional theory (DFT-D2). Calculations within the local density approximation (LDA) and GGA using PAW potentials were also performed for specific cases for the purpose of comparison. The effect of strain on the band gap and the dependence of formation energy on strain of MoS2 are also studied and discussed using the DFT-D2 method. In bulk MoS2, the orbitals shift towards the higher/lower energy area when strain is applied along the z/ x direction, respectively. The energy splitting of Mo4 d states is in the range from 0 to 2 eV, which is due to the reduction of the electronic band gap of MoS2.

  16. Large-scale structure challenges dilaton gravity in a 5D brane scenario with AdS bulk

    NASA Astrophysics Data System (ADS)

    Konikowska, Dominika

    2014-02-01

    We study a theory of dilaton gravity in a five-dimensional brane scenario, with a non-minimal coupling of the dilaton to the matter content of the universe localized on the brane. The effective gravitational equations at the brane are derived in the Einstein frame in the covariant approach, addressing certain misconceptions in the literature. We then investigate whether the observed large-scale structure of the universe can exist on the brane in this dilaton gravity scenario with an exact anti de Sitter bulk, assuming that the matter energy-momentum tensor has the form of an inhomogeneous perfect fluid. The corresponding constraint on the spatial derivative of the matter energy density is derived, and subsequently quantified using the current limits resulting from searches for variation of the Newton's constant. By confronting it with the observational data from galaxy surveys, we show that up to scales of the order of 104 Mpc, the derived bound on the spatial derivative of the matter energy density does not allow for the existence of the large-scale structure as observed today. Thus, such a dilaton gravity brane scenario is ruled out.

  17. Polydimethylsiloxane-fabricated optical fiber sensor capable of measuring both large axial and shear strain

    NASA Astrophysics Data System (ADS)

    Shen, Yu; Wang, Ziyuan; Wen, Huaihai; Zhou, Zhi

    2014-11-01

    Fiber optic sensor (FOS) has received much attention in the field of Structure Health Monitoring (SHM) due to its advantages of low weight, small size, high sensitivity multiplexing ability, free of electromagnetic interference and long durability. However, in harsh environments, structures often undergo large strain where few traditional fiber optic sensors could survive. This paper report a novel material with features of light-transparent, chemically inert, thermally stable material Polydimethylsiloxane(PDMS) fabricated large axial/shearing strain sensor. The sensor was fabricated by directly coupling a conventional signal mode fiber into half cured PDMS material using a translation stage under the inspection of a microscope. Meanwhile, a laser diode and a photo detector were used in the fabrication process to make sure the sensor achieved minimum light loss. An experiment was conducted later to investigate the sensor's transmission characteristic in 1310nm infrared laser relating with the applied axial/shearing strain. The results show that the proposed sensor survived an axial strain of 6 7.79 x 106 μɛ ; a shear of 4 6.49 x 104 μɛ with good linearity and repetition. The experiment indicates that the proposed sensor can potentially be used as strain sensing elements in Structure Health Monitoring systems under earthquake or explosion.

  18. Study on the sensing performance of OFBG under large-scale negative strain

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Hu, Qingli; Ou, Jinping

    2010-03-01

    As a new and sensitive sensing element, OFBG(Optical Fiber Bragg Grating) has been widely used in aerospace engineering and civil engineering. The sensing mechanism and properties have been widely studied by lots of researchers, but the sensing properties of OFBG under large negative strain are still destitute. In this paper, with the aids of large shrinkage performance of PP(polypropylene) during its curing, we gained about -13000 μɛ's strain changes by embeding bare OFBG inside the PP bar to study the sensing properties of OFBG in this strain level. The results show that OFBG can remain its sensing properties well---- linearity, repeatability and the shape of centre wavelength are both reasonably. And the strain sensitivity coefficient of PP-OFBG is about 0.85 pm/μɛ, this is very near with that of calculating results considering strain transmission between PP and OFBG. Which are all helpful and useful for further use of OFBG in other applications.

  19. Interband absorption strength in long-wave infrared type-II superlattices with small and large superlattice periods compared to bulk materials

    NASA Astrophysics Data System (ADS)

    Vurgaftman, I.; Belenky, G.; Lin, Y.; Donetsky, D.; Shterengas, L.; Kipshidze, G.; Sarney, W. L.; Svensson, S. P.

    2016-05-01

    The absorption spectra for the antimonide-based type-II superlattices (SLs) for detection in the long-wave infrared (LWIR) are calculated and compared to the measured data for SLs and bulk materials with the same energy gap (HgCdTe and InAsSb). We include the results for the metamorphic InAsSbx/InAsSby SLs with small periods as well as the more conventional strain-balanced InAs/Ga(In)Sb and InAs/InAsSb SLs on GaSb substrates. The absorption strength in small-period metamorphic SLs is similar to the bulk materials, while the SLs with an average lattice constant matched to GaSb have significantly lower absorption. This is because the electron-hole overlap in the strain-balanced type-II LWIR SLs occurs primarily in the hole well, which constitutes a relatively small fraction of the total thickness.

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

    SciTech Connect

    Lower, Mark D.

    2014-04-01

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

  1. Large-strain, rigid-to-rigid deformation of bistable electroactive polymers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin; Yuan, Wei; Brochu, Paul; Chen, Bin; Liu, Zhitian; Pei, Qibing

    2009-11-01

    Thermoplastic poly(tert-butyl acrylate) (PTBA) is reported as an electroactive polymer that is rigid at ambient conditions and turns into a dielectric elastomer above a transition temperature. In the rubbery state, a PTBA thin film can be electrically actuated to strains up to 335% in area expansion. The calculated actuation pressure is 3.2 MPa. The actuation is made bistable by cooling to below glass transition temperature. The PTBA represents the bistable electroactive polymer (BSEP) that can be actuated to various largely strained, rigid shapes. The application of the BSEP for refreshable Braille display, an active tactile display, is also demonstrated.

  2. Stored energy function and compressibility of compressible rubberlike materials under large strain

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    By using new invariants in the theory of finite elasticity an expression is obtained for the stored energy function of slightly compressible materials in which the effects of the distortional change (change of shape) and of the volume change are clearly separated. The volume-related terms are expressed as a function of the third invariant, the classical compressibility, and an induced anisotropy of the effective compressibility which is due to the large deformations. After evaluating the terms, using data on pressure, volume, uniaxial strain, and fractional volume change vs strain data on natural rubber from the literature, it is shown that the volume change contribution to the total stress observed in a simple tensile experiment can be clearly separated from the distortional contribution, even at finite strains.

  3. Perovskite Solar Cells with Near 100% Internal Quantum Efficiency Based on Large Single Crystalline Grains and Vertical Bulk Heterojunctions

    SciTech Connect

    Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; Keum, Jong; Puretzky, Alexander; Das, Sanjib; Ivanov, Ilia; Rouleau, Christopher; Duscher, Gerd; Geohegan, David; Xiao, Kai

    2015-07-09

    Grain boundaries (GBs) as defects in the crystal lattice detrimentally impact the power conversion efficiency (PCE) of polycrystalline solar cells, particularly in recently emerging hybrid perovskites where non-radiative recombination processes lead to significant carrier losses. Here, the beneficial effects of activated vertical GBs are demonstrated by first growing large, vertically-oriented methylammonium lead tri-iodide (CH3NH3PbI3) single-crystalline grains. We show that infiltration of p-type doped 2 -7,7 -tetrakis(N,Ndi-p-methoxyphenylamine)-9,9-spirobifluorene (Spiro-OMeTAD) into CH3NH3PbI3 films along the GBs creates space charge regions to suppress non-radiative recombination and enhance carrier collection efficiency. Solar cells with such activated GBs yielded average PCE of 16.3 ± 0.9%, which are among the best solution-processed perovskite devices. As an important alternative to growing ideal CH3NH3PbI3 single crystal films, which is difficult to achieve for such fast-crystallizing perovskites, activating GBs paves a way to design a new type of bulk heterojunction hybrid perovskite photovoltaics toward theoretical maximum PCE.

  4. Perovskite Solar Cells with Near 100% Internal Quantum Efficiency Based on Large Single Crystalline Grains and Vertical Bulk Heterojunctions

    DOE PAGESBeta

    Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; Keum, Jong; Puretzky, Alexander; Das, Sanjib; Ivanov, Ilia; Rouleau, Christopher; Duscher, Gerd; Geohegan, David; et al

    2015-07-09

    Grain boundaries (GBs) as defects in the crystal lattice detrimentally impact the power conversion efficiency (PCE) of polycrystalline solar cells, particularly in recently emerging hybrid perovskites where non-radiative recombination processes lead to significant carrier losses. Here, the beneficial effects of activated vertical GBs are demonstrated by first growing large, vertically-oriented methylammonium lead tri-iodide (CH3NH3PbI3) single-crystalline grains. We show that infiltration of p-type doped 2 -7,7 -tetrakis(N,Ndi-p-methoxyphenylamine)-9,9-spirobifluorene (Spiro-OMeTAD) into CH3NH3PbI3 films along the GBs creates space charge regions to suppress non-radiative recombination and enhance carrier collection efficiency. Solar cells with such activated GBs yielded average PCE of 16.3 ± 0.9%, whichmore » are among the best solution-processed perovskite devices. As an important alternative to growing ideal CH3NH3PbI3 single crystal films, which is difficult to achieve for such fast-crystallizing perovskites, activating GBs paves a way to design a new type of bulk heterojunction hybrid perovskite photovoltaics toward theoretical maximum PCE.« less

  5. Characterization of etch pits found on a large-grain bulk niobium superconducting radio-frequency resonant cavity

    DOE PAGESBeta

    Zhao, Xin; Ciovati, G.; Bieler, T. R.

    2010-12-15

    The performance of superconducting radio-frequency (SRF) resonant cavities made of bulk niobium is limited by nonlinear localized effects. Surface analysis of regions of higher power dissipation is thus of intense interest. Such areas (referred to as “hotspots”) were identified in a large-grain single-cell cavity that had been buffered-chemical polished and dissected for examination by high resolution electron microscopy, electron backscattered diffraction microscopy (EBSD), and optical microscopy. Pits with clearly discernible crystal facets were observed in both “hotspot” and “coldspot” specimens. The pits were found in-grain, at bicrystal boundaries, and on tricrystal junctions. They are interpreted as etch pits induced bymore » crystal defects (e.g. dislocations). All coldspots examined had a qualitatively lower density of etch pits or relatively smooth tricrystal boundary junctions. EBSD mapping revealed the crystal orientation surrounding the pits. Locations with high pit density are correlated with higher mean values of the local average misorientation angle distributions, indicating a higher geometrically necessary dislocation content. In addition, a survey of the samples by energy dispersive x-ray analysis did not show any significant contamination of the samples’ surface. In conclusion, the local magnetic field enhancement produced by the sharp-edge features observed on the samples is not sufficient to explain the observed degradation of the cavity quality factor, which starts at peak surface magnetic field as low as 20 mT.« less

  6. Characterization of etch pits found on a large-grain bulk niobium superconducting radio-frequency resonant cavity

    SciTech Connect

    Zhao, Xin; Ciovati, G.; Bieler, T. R.

    2010-12-15

    The performance of superconducting radio-frequency (SRF) resonant cavities made of bulk niobium is limited by nonlinear localized effects. Surface analysis of regions of higher power dissipation is thus of intense interest. Such areas (referred to as “hotspots”) were identified in a large-grain single-cell cavity that had been buffered-chemical polished and dissected for examination by high resolution electron microscopy, electron backscattered diffraction microscopy (EBSD), and optical microscopy. Pits with clearly discernible crystal facets were observed in both “hotspot” and “coldspot” specimens. The pits were found in-grain, at bicrystal boundaries, and on tricrystal junctions. They are interpreted as etch pits induced by crystal defects (e.g. dislocations). All coldspots examined had a qualitatively lower density of etch pits or relatively smooth tricrystal boundary junctions. EBSD mapping revealed the crystal orientation surrounding the pits. Locations with high pit density are correlated with higher mean values of the local average misorientation angle distributions, indicating a higher geometrically necessary dislocation content. In addition, a survey of the samples by energy dispersive x-ray analysis did not show any significant contamination of the samples’ surface. In conclusion, the local magnetic field enhancement produced by the sharp-edge features observed on the samples is not sufficient to explain the observed degradation of the cavity quality factor, which starts at peak surface magnetic field as low as 20 mT.

  7. Large strain stimulation promotes extracellular matrix production and stiffness in an elastomeric scaffold model.

    PubMed

    D׳Amore, Antonio; Soares, Joao S; Stella, John A; Zhang, Will; Amoroso, Nicholas J; Mayer, John E; Wagner, William R; Sacks, Michael S

    2016-09-01

    Mechanical conditioning of engineered tissue constructs is widely recognized as one of the most relevant methods to enhance tissue accretion and microstructure, leading to improved mechanical behaviors. The understanding of the underlying mechanisms remains rather limited, restricting the development of in silico models of these phenomena, and the translation of engineered tissues into clinical application. In the present study, we examined the role of large strip-biaxial strains (up to 50%) on ECM synthesis by vascular smooth muscle cells (VSMCs) micro-integrated into electrospun polyester urethane urea (PEUU) constructs over the course of 3 weeks. Experimental results indicated that VSMC biosynthetic behavior was quite sensitive to tissue strain maximum level, and that collagen was the primary ECM component synthesized. Moreover, we found that while a 30% peak strain level achieved maximum ECM synthesis rate, further increases in strain level lead to a reduction in ECM biosynthesis. Subsequent mechanical analysis of the formed collagen fiber network was performed by removing the scaffold mechanical responses using a strain-energy based approach, showing that the denovo collagen also demonstrated mechanical behaviors substantially better than previously obtained with small strain training and comparable to mature collagenous tissues. We conclude that the application of large deformations can play a critical role not only in the quantity of ECM synthesis (i.e. the rate of mass production), but also on the modulation of the stiffness of the newly formed ECM constituents. The improved understanding of the process of growth and development of ECM in these mechano-sensitive cell-scaffold systems will lead to more rational design and manufacturing of engineered tissues operating under highly demanding mechanical environments. PMID:27344402

  8. Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

    PubMed Central

    Yao, Yao; Glisic, Branko

    2015-01-01

    Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs. PMID:25853407

  9. Biaxial Tensile Test of Cold Rolled IF Steel Sheet for Large Plastic Strain Range

    NASA Astrophysics Data System (ADS)

    Enatsu, Ryotaro; Kuwabara, Toshihiko

    2011-08-01

    Deformation behavior of cold rolled IF steel sheet (SPCE) under biaxial tension has been investigated for large plastic strain range over 15%. The test material was bent and TIG welded to form a tubular specimen with an outer diameter of 46.2 mm and wall thickness of 0.8 mm. The tubular specimens have been subjected to linear stress paths in the first quadrant of stress space with the use of a servo-controlled tension-internal pressure testing machine developed by one of the authors [T. Kuwabara, K. Yoshida, K. Narihara, S. Takahashi, Anisotropic plastic deformation of extruded aluminum alloy tube under axial forces and internal pressure, Int. J. Plasticity 21, 101-117 (2005)]. Moreover, biaxial tensile tests using a cruciform specimen have also been carried out to more precisely measure the deformation behavior for a small strain range following initial yielding. True stress-true plastic strain curves, contours of plastic work in stress space and the directions of plastic strain rates have been measured and compared with those calculated using selected yield functions: the von Mises, Hill's quadratic and Yld2000-2d [Barlat, F., Brem, J.C., Yoon, J.W., Chung, K., Dick, R.E., Lege, D.J., Pourboghrat, F., Choi, S.H., Chu, E., Plane stress yield function for aluminum alloy sheets—Part 1: Theory. Int. J. Plasticity 19, 1297-1319 (2003)]. The plastic deformation behavior up to a work equivalent plastic strain of ɛ0p = 0.19 has been successfully measured. It is found that the test material exhibits differential hardening and that the Yld2000-2d yield function with an exponent of six most closely predicts the contours of plastic work and the directions of plastic strain rates.

  10. High-rate Plastic Deformation of Nanocrystalline Tantalum to Large Strains: Molecular Dynamics Simulation

    SciTech Connect

    Rudd, R E

    2009-02-05

    Recent advances in the ability to generate extremes of pressure and temperature in dynamic experiments and to probe the response of materials has motivated the need for special materials optimized for those conditions as well as a need for a much deeper understanding of the behavior of materials subjected to high pressure and/or temperature. Of particular importance is the understanding of rate effects at the extremely high rates encountered in those experiments, especially with the next generation of laser drives such as at the National Ignition Facility. Here we use large-scale molecular dynamics (MD) simulations of the high-rate deformation of nanocrystalline tantalum to investigate the processes associated with plastic deformation for strains up to 100%. We use initial atomic configurations that were produced through simulations of solidification in the work of Streitz et al [Phys. Rev. Lett. 96, (2006) 225701]. These 3D polycrystalline systems have typical grain sizes of 10-20 nm. We also study a rapidly quenched liquid (amorphous solid) tantalum. We apply a constant volume (isochoric), constant temperature (isothermal) shear deformation over a range of strain rates, and compute the resulting stress-strain curves to large strains for both uniaxial and biaxial compression. We study the rate dependence and identify plastic deformation mechanisms. The identification of the mechanisms is facilitated through a novel technique that computes the local grain orientation, returning it as a quaternion for each atom. This analysis technique is robust and fast, and has been used to compute the orientations on the fly during our parallel MD simulations on supercomputers. We find both dislocation and twinning processes are important, and they interact in the weak strain hardening in these extremely fine-grained microstructures.

  11. Influence of the Crystalline Phase on Strain-Rate Sensitivity of a Zr-Cu-Ni-Al Bulk Metallic Glass at Room Temperature

    NASA Astrophysics Data System (ADS)

    Huang, Yongjiang; Zheng, Wei; Shen, Jun

    2012-12-01

    In this work, Zr53Cu18.7Ni12Al16.3 alloy has been cast into rod samples with different diameters. Glassy composites with various volume fractions of quenched-in crystalline are obtained. Their mechanical behaviors and fracture mechanisms have been investigated upon both quasistatic and dynamic loading. As the volume fraction of crystalline phase increases, the increase in the strain-rate sensitivity exponent could be attributed to the combination of the reduction of the shear band-related deformability and the enhancement of the dislocation-related deformability. These results may shed more insight on optimizing the microstructure and performance of bulk metallic glass composites in the future.

  12. Large difference between the magnetic properties of Ba and Ti co-doped BiFeO3 bulk materials and their corresponding nanoparticles prepared by ultrasonication

    NASA Astrophysics Data System (ADS)

    Ahmmad, Bashir; Kanomata, Kensaku; Koike, Kunihiro; Kubota, Shigeru; Kato, Hiroaki; Hirose, Fumihiko; Billah, Areef; Jalil, M. A.; Basith, M. A.

    2016-07-01

    The ceramic pellets of the nominal compositions Bi0.7Ba0.3Fe1‑x Ti x O3 (x  =  0.00–0.20) were prepared initially by standard solid state reaction technique. The pellets were then ground into micrometer-sized powders and mixed with isopropanol in an ultrasonic bath to prepare nanoparticles. The x-ray diffraction patterns demonstrate the presence of a significant number of impurity phases in bulk powder materials. Interestingly, these secondary phases were completely removed due to the sonication of these bulk powder materials for 60 minutes. The field and temperature dependent magnetization measurements exhibited significant difference between the magnetic properties of the bulk materials and their corresponding nanoparticles. We anticipate that the large difference in the magnetic behavior may be associated with the presence and absence of secondary impurity phases in the bulk materials and their corresponding nanoparticles, respectively. The leakage current density of the bulk materials was also found to suppress in the ultrasonically prepared nanoparticles compared to that of bulk counterparts.

  13. Quantifying Bulk Electrode Strain and Material Displacement within Lithium Batteries via High‐Speed Operando Tomography and Digital Volume Correlation

    PubMed Central

    Finegan, Donal P.; Tudisco, Erika; Scheel, Mario; Robinson, James B.; Taiwo, Oluwadamilola O.; Eastwood, David S.; Lee, Peter D.; Di Michiel, Marco; Bay, Brian; Hall, Stephen A.; Hinds, Gareth; Brett, Dan J. L.

    2015-01-01

    Tracking the dynamic morphology of active materials during operation of lithium batteries is essential for identifying causes of performance loss. Digital volume correlation (DVC) is applied to high‐speed operando synchrotron X‐ray computed tomography of a commercial Li/MnO2 primary battery during discharge. Real‐time electrode material displacement is captured in 3D allowing degradation mechanisms such as delamination of the electrode from the current collector and electrode crack formation to be identified. Continuum DVC of consecutive images during discharge is used to quantify local displacements and strains in 3D throughout discharge, facilitating tracking of the progression of swelling due to lithiation within the electrode material in a commercial, spiral‐wound battery during normal operation. Displacement of the rigid current collector and cell materials contribute to severe electrode detachment and crack formation during discharge, which is monitored by a separate DVC approach. Use of time‐lapse X‐ray computed tomography coupled with DVC is thus demonstrated as an effective diagnostic technique to identify causes of performance loss within commercial lithium batteries; this novel approach is expected to guide the development of more effective commercial cell designs. PMID:27610334

  14. An Evaluation of Constitutive Laws and their Ability to Predict Flow Stress over Large Variations in Temperature, Strain, and Strain Rate Characteristic of Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kuykendall, Katherine

    2011-07-01

    Constitutive laws commonly used to model friction stir welding have been evaluated, both qualitatively and quantitatively, and a new application of a constitutive law which can be extended to materials commonly used in FSW is presented. Existing constitutive laws have been classified as path-dependent or path-independent. Path-independent laws have been further classified according to the physical phenomena they capture: strain hardening, strain rate hardening, and/or thermal softening. Path-dependent laws can track gradients in temperature and strain rate characteristic to friction stir welding; however, path-independent laws cannot. None of the path-independent constitutive laws evaluated has been validated over the full range of strain, strain rate, and temperature in friction stir welding. Holding all parameters other than constitutive law constant in a friction stir weld model resulted in temperature differences of up to 21%. Varying locations for maximum temperature difference indicate that the constitutive laws resulted in different temperature profiles. The Sheppard and Wright law is capable of capturing saturation but incapable of capturing strain hardening with errors as large as 57% near yield. The Johnson-Cook law is capable of capturing strain hardening; however, its inability to capture saturation causes over-predictions of stress at large strains with errors as large as 37% near saturation. The Kocks and Mecking model is capable of capturing strain hardening and saturation with errors less than 5% over the entire range of plastic strain. The Sheppard and Wright and Johnson-Cook laws are incapable of capturing transients characteristic of material behavior under interrupted temperature or strain rate. The use of a state variable in the Kocks and Mecking law allows it to predict such transients. Constants for the Kocks and Mecking model for AA 5083, AA 3004, and Inconel 600 were determined from Atlas of Formability data. Constants for AA 5083 and AA

  15. The effect of stress-state on the large strain inelastic deformation behavior of 304L stainless steel

    SciTech Connect

    Miller, M.P.; McDowell, D.L.

    1996-01-01

    In metals, large strain inelastic deformation processes such as the formation of a preferred crystallographic orientation (crystallographic texture) and strain hardening processes such as the formation and evolution of dislocation substructures depend on stress-state. Much of the current large strain research has focused on texture. Crystallographic texture development and strain-hardening processes each contribute to the overall material behavior, and a complete description of large strain inelastic material response should reflect both. An investigation of the large strain behavior of 304L stainless steel (SS 304L) subjected to compression, torsion, and sequences of compression followed by torsion and torsion followed by tension is reported. This paper focuses on the stress-state dependence of strain-hardening processes as well as the relative effect such processes have on the overall material behavior. To characterize these processes, transmission electron microscopy (TEM) as well as magnetization investigations were conducted at different strain levels and under different deformation modes. The {gamma} {yields} {alpha}{prime} martensitic transformation which occurs in this material was found to be related to both the strain level and stress state. Dislocation substructures in the form of Taylor lattices, dense dislocation walls, and microbands were also present. The ramifications of using a thin-walled tubular torsion specimen were also explored.

  16. Bulk undercooling

    NASA Technical Reports Server (NTRS)

    Kattamis, T. Z.

    1984-01-01

    Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.

  17. Large-size ultrahigh strength Ni-based bulk metallic glassy matrix composites with enhanced ductility fabricated by spark plasma sintering

    SciTech Connect

    Xie Guoqiang; Louzguine-Luzgin, Dmitri V.; Kimura, Hisamichi; Inoue, Akihisa; Wakai, Fumihiro

    2008-03-24

    Ni-based bulk glassy alloy composites (GACs) simultaneously with ultrahigh strength and enhanced ductility and satisfying large-size requirements were fabricated by spark plasma sintering of gas-atomized Ni{sub 52.5}Nb{sub 10}Zr{sub 15}Ti{sub 15}Pt{sub 7.5} glassy alloy powder blend with ceramic or metal powders. No crystallization of metallic glassy matrix and good bonding state between the particles are responsible for good mechanical properties of the fabricated bulk GACs. The improvement of plastic ductility of the fabricated bulk GACs originates from the structural inhomogeneity caused by the particles inclusion. The additional particulates act as a resisting media causing deviation, branching, and multiplication of shear bands.

  18. Large-size ultrahigh strength Ni-based bulk metallic glassy matrix composites with enhanced ductility fabricated by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Xie, Guoqiang; Louzguine-Luzgin, Dmitri V.; Kimura, Hisamichi; Inoue, Akihisa; Wakai, Fumihiro

    2008-03-01

    Ni-based bulk glassy alloy composites (GACs) simultaneously with ultrahigh strength and enhanced ductility and satisfying large-size requirements were fabricated by spark plasma sintering of gas-atomized Ni52.5Nb10Zr15Ti15Pt7.5 glassy alloy powder blend with ceramic or metal powders. No crystallization of metallic glassy matrix and good bonding state between the particles are responsible for good mechanical properties of the fabricated bulk GACs. The improvement of plastic ductility of the fabricated bulk GACs originates from the structural inhomogeneity caused by the particles inclusion. The additional particulates act as a resisting media causing deviation, branching, and multiplication of shear bands.

  19. Large elastic strain and elastocaloric effect caused by lattice softening in an iron-palladium alloy.

    PubMed

    Kakeshita, Tomoyuki; Xiao, Fei; Fukuda, Takashi

    2016-08-13

    A Fe-31.2Pd (at.%) alloy exhibits a weak first-order martensitic transformation from a cubic structure to a tetragonal structure near 230 K. This transformation is associated with significant softening of elastic constant C'. Because of the softening, the alloy shows a large elastic strain of more than 6% in the [001] direction. In addition, the alloy has a critical point and shows a high elastocaloric effect in a wide temperature range for both the parent and the martensite phases.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. PMID:27402932

  20. Study of Strains of The Earth Surface In Large Cities By Satellite Methods

    NASA Astrophysics Data System (ADS)

    Blank, L.; Genike, A.; Guseva, T.

    In recent years the problem of learning modern geodynamic processes has increased sharply both within the limits of all terrestrial globe, and in its separate regions. Terri- tories of large cities are the focus of increased attention. Severe distractions of build- ings and engineering facilities take place due to strains on the earth's surface caused by intensive development of underground space, violations and disturbance of hy- drocondition, vibrations of a geologic medium by transportation facilities, and other reasons. Such phenomena became a reason for geodesic monitoring of the largest megalopolis of Russia, the city of Moscow. A geodynamic GPS network was created. The network encompasses the city and its suburbs. At the present time, nine series of high-precision measurements were taken by GPS, mainly during spring and fall seasons. The results of this analysis indicated that the strain on the outer layer of geologic patterns could reach 1-4 centimeters in the territory of Moscow. The central part of the city presents peculiar lowering. The joint analysis of geodesic, geophysical and geologic studies al- lowed the conclusion to be drawn that level variations of groundwaters and formation of depressive whirlpools are the reasons for these deformations. Results of GPS monitoring demonstrate the necessity to continue keeping track of developing strains on the earth's surface, as well as performing additional geophysical observations.

  1. Large strain experiments on crystal- and bubble-bearing silicic magmas

    NASA Astrophysics Data System (ADS)

    Pistone, M.; Caricchi, L.; Burlini, L.; Ulmer, P.

    2009-12-01

    -enriched shear bands. The localization of deformation in these lower viscosity regions results in a decrease of viscosity with increasing strain (shear thinning effects). BIBLIOGRAPHY Paterson M.S., Olgaard D.L. (2000). Rock deformation tests to large shear strains in torsion. Journal of Structural Geology 22, 1341-1358. Webb S.L., Dingwell D.B. (1990). Non-Newtonian rheology of igneous melts at high stresses and strain rates: experimental results for rhyolite, andesite, basalt and nephelinite. Journal of Geophysical Research 95 (B10), 15695-15701.

  2. Thermodynamically consistent phase field approach to dislocation evolution at small and large strains

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; Javanbakht, Mahdi

    2015-09-01

    A thermodynamically consistent, large strain phase field approach to dislocation nucleation and evolution at the nanoscale is developed. Each dislocation is defined by an order parameter, which determines the magnitude of the Burgers vector for the given slip planes and directions. The kinematics is based on the multiplicative decomposition of the deformation gradient into elastic and plastic contributions. The relationship between the rates of the plastic deformation gradient and the order parameters is consistent with phenomenological crystal plasticity. Thermodynamic and stability conditions for homogeneous states are formulated and satisfied by the proper choice of the Helmholtz free energy and the order parameter dependence on the Burgers vector. They allow us to reproduce desired lattice instability conditions and a stress-order parameter curve, as well as to obtain a stress-independent equilibrium Burgers vector and to avoid artificial dissipation during elastic deformation. The Ginzburg-Landau equations are obtained as the linear kinetic relations between the rate of change of the order parameters and the conjugate thermodynamic driving forces. A crystalline energy coefficient for dislocations is defined as a periodic step-wise function of the coordinate along the normal to the slip plane, which provides an energy barrier normal to the slip plane and determines the desired, mesh-independent height of the dislocation bands for any slip system orientation. Gradient energy contains an additional term, which excludes the localization of a dislocation within a height smaller than the prescribed height, but it does not produce artificial interface energy. An additional energy term is introduced that penalizes the interaction of different dislocations at the same point. Non-periodic boundary conditions for dislocations are introduced which include the change of the surface energy due to the exit of dislocations from the crystal. Obtained kinematics, thermodynamics

  3. A computational framework for polyconvex large strain elasticity for geometrically exact beam theory

    NASA Astrophysics Data System (ADS)

    Ortigosa, Rogelio; Gil, Antonio J.; Bonet, Javier; Hesch, Christian

    2016-02-01

    In this paper, a new computational framework is presented for the analysis of nonlinear beam finite elements subjected to large strains. Specifically, the methodology recently introduced in Bonet et al. (Comput Methods Appl Mech Eng 283:1061-1094, 2015) in the context of three dimensional polyconvex elasticity is extended to the geometrically exact beam model of Simo (Comput Methods Appl Mech Eng 49:55-70, 1985), the starting point of so many other finite element beam type formulations. This new variational framework can be viewed as a continuum degenerate formulation which, moreover, is enhanced by three key novelties. First, in order to facilitate the implementation of the sophisticated polyconvex constitutive laws particularly associated with beams undergoing large strains, a novel tensor cross product algebra by Bonet et al. (Comput Methods Appl Mech Eng 283:1061-1094, 2015) is adopted, leading to an elegant and physically meaningful representation of an otherwise complex computational framework. Second, the paper shows how the novel algebra facilitates the re-expression of any invariant of the deformation gradient, its cofactor and its determinant in terms of the classical beam strain measures. The latter being very useful whenever a classical beam implementation is preferred. This is particularised for the case of a Mooney-Rivlin model although the technique can be straightforwardly generalised to other more complex isotropic and anisotropic polyconvex models. Third, the connection between the two most accepted restrictions for the definition of constitutive models in three dimensional elasticity and beams is shown, bridging the gap between the continuum and its degenerate beam description. This is carried out via a novel insightful representation of the tangent operator.

  4. Dislocation accumulation at large plastic strains -- An approach to the theoretical strength of materials

    SciTech Connect

    Embury, J.D. |; Han, K.

    1999-04-01

    The usual method of introducing engineers to the concept of dislocations and their role in plastic flow is to compare an estimate of the theoretical strength of solid (of order {micro}/30 where {micro} is the shear modulus) and the observed strength of either single crystals ({mu}/10{sup 4}) or practical engineering material such as structural steels where the yield stress in shear is of order {mu}/10{sup 3}. However, if one considers the problem in reverse, one can consider the accumulation of dislocations as an important mechanism by which one can produce engineering materials in which the strength level approaches the theoretical strength. If one assumes that the flow stress can be expressed in terms of te mean free path between stored dislocations or as the square root of the global dislocation density, then one can see the influence of dislocation density in a diagrammatic form. It is clear that the strengthening by dislocation accumulation due to large imposed plastic strains represents an important approach both to the development of new, potentially valuable, engineering materials and an important area of basic understanding in terms of the mechanical response of materials close to their theoretical strength. Thus, this article will survey some of the factors which influence dislocation accumulation at large strains and the consequences of such accumulation processes.

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

    SciTech Connect

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

    2014-10-13

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

  6. The response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress

    NASA Astrophysics Data System (ADS)

    Holmquist, T. J.; Bradley, J.; Dwivedi, A.; Casem, D.

    2016-05-01

    This article presents the response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress. Laboratory data from the literature, and new test data provided here, are used in the evaluation. The new data include uniaxial stress compression tests (at various strain rates and temperatures) and uniaxial stress tension tests (at low strain rates and ambient temperatures). The compression tests include experiments at ˙ɛ = 13,000 s-1, significantly extending the range of known strain rate data. The observed behavior of PMMA includes the following: it is brittle in compression at high rates, and brittle in tension at all rates; strength is dependent on the pressure, strain, strain rate, temperature, and the intermediate principal stress; the shear modulus increases as the pressure increases; and it is highly compressible. Also presented are novel, high velocity impact tests (using high-speed imaging) that provide insight into the initiation and evolution of damage. Lastly, computational constitutive models for pressure, strength, and failure are presented that provide responses that are in good agreement with the laboratory data. The models are used to compute several ballistic impact events for which experimental data are available.

  7. Finite-strain large-deflection elastic-viscoplastic finite-element transient response analysis of structures

    NASA Technical Reports Server (NTRS)

    Rodal, J. J. A.; Witmer, E. A.

    1979-01-01

    A method of analysis for thin structures that incorporates finite strain, elastic-plastic, strain hardening, time dependent material behavior implemented with respect to a fixed configuration and is consistently valid for finite strains and finite rotations is developed. The theory is formulated systematically in a body fixed system of convected coordinates with materially embedded vectors that deform in common with continuum. Tensors are considered as linear vector functions and use is made of the dyadic representation. The kinematics of a deformable continuum is treated in detail, carefully defining precisely all quantities necessary for the analysis. The finite strain theory developed gives much better predictions and agreement with experiment than does the traditional small strain theory, and at practically no additional cost. This represents a very significant advance in the capability for the reliable prediction of nonlinear transient structural responses, including the reliable prediction of strains large enough to produce ductile metal rupture.

  8. Fluid-like flows in large-strain deformation of metals

    NASA Astrophysics Data System (ADS)

    Yeung, Ho; Sagapuram, Dinakar; Viswanathan, Koushik; Sundaram, Narayan; Mahato, Anirban; Trumble, Kevin; Chandrasekar, Srinivasan

    Laminar or smooth plastic flow, commonly observed in large deformation of metals, becomes unstable under certain conditions, resulting in inhomogeneous plastic flow. Using in situ imaging, we demonstrate the unique features of two inhomogeneous flow modes in metal plasticity -- the well-known shear band flow and the recently discovered sinuous flow -- and methods for suppressing them. Both modes occur via a two stage process -- nucleation and flow development. The nucleation stage results in a weak material zone and the development stage involves imposition of significant strains. In the case of shear bands, using additional micro-marker techniques, we show that the second stage is well described by a viscous slider model. As a result, controlling the second stage causes band formation to cease. We demonstrate the use of this method -- Passive Geometric Flow control -- to form long strips from metallic alloys that are difficult to form conventionally. For sinuous flow, nucleation and flow formation kinematics show remarkable resemblance with flows in complex fluids. The nucleation stage can be altered using suitable ink coatings on the free surface or by surface pre-straining, and we use this idea to demonstrate complete sinuous flow suppression. Membership pending.

  9. Contribution to the study of the anisotropic viscoelasticity of large strains: The case of the monocrystal

    NASA Astrophysics Data System (ADS)

    Boukadia, Joseph Aime Michel

    1990-01-01

    The anisotropic viscoelasticity of large strains and torsion are investigated. In a phenomenologic approach, it is shown that the problem of applying the concepts of plasticity is the choice of the Torsion's referent system. The viscoplasticity in single crystals is also investigated. A rotating reference system is applied to describe kinetic phenomena of single crystals. The mechanical behavior of a face centered cubic single crystal, concerning viscosity, plasticity, and viscoplasticity, are analyzed by simple shear and failure mechanisms. The Bingham and Norton-Hoff methods are applied. The elastic phenomena can be taken into account without difficulties. The approach is constrained by the hypothesis that symmetric systems are symmetrically activated. However, by the hypothesis a two dimensional response was obtained. The model can be applied to the analysis of polycrystals.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  11. Influence of crossed fields in structures combining large grain, bulk (RE)BCO superconductors and soft ferromagnetic discs

    NASA Astrophysics Data System (ADS)

    Philippe, M. P.; Fagnard, J. F.; Wéra, L.; Morita, M.; Nariki, S.; Teshima, H.; Caps, H.; Vanderheyden, B.; Vanderbemden, P.

    2016-03-01

    Bulk (RE)BCO superconductors are able to trap record magnetic fields and can be used as powerful permanent magnets in various engineering applications such as rotating machines and magnetic bearings. When such superconducting (SC) “trapped field magnets” are combined to a ferromagnetic (FM) disc, the total magnetic moment is increased with respect to that of the superconductor alone. In the present work, we study experimentally the magnetic behaviour of such hybrid FM/SC structures when they are subjected to cycles of applied field that are orthogonal to their permanent magnetization, i.e. a “crossed-field” configuration. Experimental results show that the usual “crossed-field demagnetization” caused by the cycles of transverse field is strongly reduced in the presence of the ferromagnet.

  12. Nonlinear material parameter estimation for characterizing hyper elastic large strain models

    NASA Astrophysics Data System (ADS)

    Gendy, A. S.; Saleeb, A. F.

    An automated, systematic, and computationally efficient methodology to estimate the material parameters for characterizing general nonlinear material models for large strain analysis (e.g., hyperelastic and hyper foam materials) is presented. Such constitutive material models often require a large number of material constants to describe a host of physical phenomena and complicated deformation mechanisms. Extracting such material constants for a model from the volumes of data generated in the test laboratory is usually a very difficult, and frustrating. The integrated code COMPARE (that is an acronym of Constitutive Material PARameter Estimator) is being developed to enable the determination of an ``optimum'' set material parameters by minimizing the errors between the experimental test data and the predicted response. The key ingredients of COMPARE are listed as follows: (i) primal analysis tools (response functionals) for differential form of constitutive models; (ii) sensitivity analysis; (iii) optimization technique of an error/cost function; and (iv) graphical user interface. The code COMPARE casts the estimation of the material parameters as a minimum-error, weighted-multiobjective, optimization problem. Detailed derivations and results generated by applying the proposed technique to a comprehensive set of test data are given. These results have clearly demonstrated the great practical utility of the automated scheme developed.

  13. Microstructural characterization of in situ MXCT images of high density foams under large strains

    SciTech Connect

    Patterson, Brian M; Gleiman, Seth; Marks, Trevor G; Milstein, Fredrick

    2009-01-01

    relative-density of the foam; however, there exists a gap in the understanding of how the foam microstructure affects the mechanical response of the foam. This is due in large part to the difficulty of characterizing foam structures in 3D, especially foams of high relative-density. Most elastomeric foams are manufactured by the introduction of a gas into a cross-linking polymer. The developing foam microstructure has a complex dependence on the polymer viscosity and rate of polymerization, resulting in a randomly arranged pore structure with a large distribution of pore sizes. One approach is to characterize foam microstructures solely in terms of the cross-sectional shape and vector arrangement of the strut matrix, since it is this matrix that supports the stresses upon loading of the foam; yet as the density of a foam is increased, the very definition of what constitutes a strut brakes down. Another, perhaps easier to visualize, characterization of foam microstructure can come from a description of the pore shape and arrangement. Given the random nature of the microstructures of blown foam, both approaches are useful and valid. This paper describes our work aimed at linking the mechanical response and microstructural evolution of high relative-density foam as it undergoes large deformation. This work consists of several inter-related parts, including (i) measuring the compressive stress-strain response, as illustrated in Fig. 1, (ii) obtaining in situ micro X-ray computed tomography (MXCT) images of high relative-density foams undergoing large strains, and (iii) developing mathematical, computer aided, methodologies to perform image analysis and calculations of parameters that characterize the pores and struts. By using MXCT, a non-invasive technique for imaging the internal structure of materials, we are able to observe, internally, individual struts and pores as they undergo large deformation. Here we describe our computer aided image analysis methodologies and present

  14. Large Differences in Aging Phenotype between Strains of the Short-Lived Annual Fish Nothobranchius furzeri

    PubMed Central

    Benedetti, Mauro; Roncaglia, Paola; Cattaneo, Antonino; Domenici, Luciano; Cellerino, Alessandro

    2008-01-01

    Background A laboratory inbred strain of the annual fish Nothobranchius furzeri shows exceptionally short life expectancy and accelerated expression of age markers. In this study, we analyze new wild-derived lines of this short-lived species. Methodology/Principal Findings We characterized captive survival and age-related traits in F1 and F2 offspring of wild-caught N. furzeri. Wild-derived N. furzeri lines showed expression of lipofuscin and neurodegeneration at age 21 weeks. Median lifespan in the laboratory varied from to 20 to 23 weeks and maximum lifespan from 25 to 32 weeks. These data demonstrate that rapid age-dependent decline and short lifespan are natural characteristics of this species. The N. furzeri distribution range overlaps with gradients in altitude and aridity. Fish from more arid habitats are expected to experience a shorter survival window in the wild. We tested whether captive lines stemming from semi-arid and sub-humid habitats differ in longevity and expression of age-related traits. We detected a clear difference in age-dependent cognitive decline and a slight difference in lifespan (16% for median, 15% for maximum lifespan) between these lines. Finally, we observed shorter lifespan and accelerated expression of age-related markers in the inbred laboratory strain compared to these wild-derived lines. Conclusions/Significance Owing to large differences in aging phenotypes in different lines, N. furzeri could represent a model system for studying the genetic control of life-history traits in natural populations. PMID:19052641

  15. Large-scale assembly of highly sensitive Si-based flexible strain sensors for human motion monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Bing-Chang; Wang, Hui; Zhao, Yu; Li, Fan; Ou, Xue-Mei; Sun, Bao-Quan; Zhang, Xiao-Hong

    2016-01-01

    Silicon is the dominant semiconductor in modern society, but the rigid nature of most Si structures hinders its applications in flexible electronics. In this work, Si-based flexible strain sensors are fabricated with Si fabric consisting of long Si nanowires. The as-obtained sensors demonstrate a large strain range of 50% and a gauge factor of up to 350, which are sufficient to detect human motions with superior performance over traditional sensors. The results reveal that the assembling strategy may potentially be applied to large-scale fabrication of highly sensitive, flexible strain sensors for emerging applications such as healthcare and sports monitoring. Moreover, the Si fabric would also enable broad applications of Si materials in other flexible and wearable devices such as flexible optoelectronics and displays.Silicon is the dominant semiconductor in modern society, but the rigid nature of most Si structures hinders its applications in flexible electronics. In this work, Si-based flexible strain sensors are fabricated with Si fabric consisting of long Si nanowires. The as-obtained sensors demonstrate a large strain range of 50% and a gauge factor of up to 350, which are sufficient to detect human motions with superior performance over traditional sensors. The results reveal that the assembling strategy may potentially be applied to large-scale fabrication of highly sensitive, flexible strain sensors for emerging applications such as healthcare and sports monitoring. Moreover, the Si fabric would also enable broad applications of Si materials in other flexible and wearable devices such as flexible optoelectronics and displays. Electronic supplementary information (ESI) available: The morphological and structural characterization of the silicon nanowires, the plot of the relative resistance change versus cubic strain, and the relationship between the width of the gap and the exerted strain. See DOI: 10.1039/c5nr07546g

  16. Low-dimensional transport and large thermoelectric power factors in bulk semiconductors by band engineering of highly directional electronic states.

    PubMed

    Bilc, Daniel I; Hautier, Geoffroy; Waroquiers, David; Rignanese, Gian-Marco; Ghosez, Philippe

    2015-04-01

    Thermoelectrics are promising for addressing energy issues but their exploitation is still hampered by low efficiencies. So far, much improvement has been achieved by reducing the thermal conductivity but less by maximizing the power factor. The latter imposes apparently conflicting requirements on the band structure: a narrow energy distribution and a low effective mass. Quantum confinement in nanostructures and the introduction of resonant states were suggested as possible solutions to this paradox, but with limited success. Here, we propose an original approach to fulfill both requirements in bulk semiconductors. It exploits the highly directional character of some orbitals to engineer the band structure and produce a type of low-dimensional transport similar to that targeted in nanostructures, while retaining isotropic properties. Using first-principle calculations, the theoretical concept is demonstrated in Fe2YZ Heusler compounds, yielding power factors 4 to 5 times larger than in classical thermoelectrics at room temperature. Our findings are totally generic and rationalize the search of alternative compounds with similar behavior. Beyond thermoelectricity, these might be relevant also in the context of electronic, superconducting, or photovoltaic applications. PMID:25884131

  17. Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers

    NASA Astrophysics Data System (ADS)

    Xu, Jin-Long; Sun, Yi-Jian; He, Jing-Liang; Wang, Yan; Zhu, Zhao-Jie; You, Zhen-Yu; Li, Jian-Fu; Chou, Mitch M. C.; Lee, Chao-Kuei; Tu, Chao-Yang

    2015-10-01

    Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm2 at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices.

  18. Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers.

    PubMed

    Xu, Jin-Long; Sun, Yi-Jian; He, Jing-Liang; Wang, Yan; Zhu, Zhao-Jie; You, Zhen-Yu; Li, Jian-Fu; Chou, Mitch M C; Lee, Chao-Kuei; Tu, Chao-Yang

    2015-01-01

    Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm(2) at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices. PMID:26442909

  19. Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers

    PubMed Central

    Xu, Jin-Long; Sun, Yi-Jian; He, Jing-Liang; Wang, Yan; Zhu, Zhao-Jie; You, Zhen-Yu; Li, Jian-Fu; Chou, Mitch M. C.; Lee, Chao-Kuei; Tu, Chao-Yang

    2015-01-01

    Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm2 at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices. PMID:26442909

  20. Large recovery strain in Fe-Mn-Si-based shape memory steels obtained by engineering annealing twin boundaries

    NASA Astrophysics Data System (ADS)

    Wen, Y. H.; Peng, H. B.; Raabe, D.; Gutierrez-Urrutia, I.; Chen, J.; Du, Y. Y.

    2014-09-01

    Shape memory alloys are a unique class of materials that can recover their original shape upon heating after a large deformation. Ti-Ni alloys with a large recovery strain are expensive, while low-cost conventional processed Fe-Mn-Si-based steels suffer from a low recovery strain (<3%). Here we show that the low recovery strain results from interactions between stress-induced martensite and a high density of annealing twin boundaries. Reducing the density of twin boundaries is thus a critical factor for obtaining a large recovery strain in these steels. By significantly suppressing the formation of twin boundaries, we attain a tensile recovery strain of 7.6% in an annealed cast polycrystalline Fe-20.2Mn-5.6Si-8.9Cr-5.0Ni steel (weight%). Further attractiveness of this material lies in its low-cost alloying components and simple synthesis-processing cycle consisting only of casting plus annealing. This enables these steels to be used at a large scale as structural materials with advanced functional properties.

  1. Multilocus analysis reveals large genetic diversity in Kluyveromyces marxianus strains isolated from Parmigiano Reggiano and Pecorino di Farindola cheeses.

    PubMed

    Fasoli, Giuseppe; Barrio, Eladio; Tofalo, Rosanna; Suzzi, Giovanna; Belloch, Carmela

    2016-09-16

    In the present study, we have analysed the genetic diversity in Kluyveromyces marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola cheesemaking environment. Molecular typing methods inter-RTL fingerprint and mtDNA RFLPs, as well as, sequence diversity and heterozygosity in the intergenic region between KmSSB1 and KmRIO2 genes and analysis of the mating locus were applied to 54 K. marxianus strains. Inter-RTL fingerprint revealed a large degree of genetic heterogeneity and clustering allowed differentiation of K. marxianus strains from different geographical origins. In general, inter-LTR profiles were more discriminating than RFLPs of mtDNA; however our results also indicate that both techniques could be complementary unveiling different degrees of genetic diversity. Sequence analysis of the intergenic region between KmSSB1 and KmRIO2 genes revealed 26 variable positions in which a double peak could be observed in the sequence chromatogram. Further analysis revealed the presence of heterozygous strains in the K. marxianus population isolated from Parmigiano Reggiano. On the other hand, all strains isolated from Pecorino di Farindola were homozygous. Two very different groups of haplotypes could be observed as well as mixtures between them. Phylogenetic reconstruction divided K. marxianus dairy strains into two separate populations. A few heterozygous strains in an intermediate position between them could also be observed. Mating type locus analysis revealed a large population of diploid strains containing both MATa and MATα alleles and few haploid strains, most of them presenting the MATα allele. Different scenarios explaining the presence and maintaining of homozygous and heterozygous diploids as well as hybrids between them in the Parmigiano Reggiano K. marxianus population are proposed. A principal component analysis supported the large differences between K. marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola. PMID:27294555

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  3. Suppression of repeated adiabatic shear banding by dynamic large strain extrusion machining

    NASA Astrophysics Data System (ADS)

    Cai, S. L.; Dai, L. H.

    2014-12-01

    High speed machining (HSM) is an advanced production technology with great future potential. Chip serration or segmentation is a commonly observed phenomenon during high speed machining of metals, which is found to be ascribed to a repeated shear band formation fueled by thermo-plastic instability occurring within the primary shear zone. The occurrence of serrated chips leads to the cutting force fluctuation, decreased tool life, degradation of the surface finish and less accuracy in machine parts during high speed machining. Hence, understanding and controlling serrated chip formation in HSM are extremely important. In this work, a novel dynamic large strain extrusion machining (DLSEM) technique is developed for suppressing formation of serrated chips. The systematic DLSEM experiments of Ti-6Al-4V and Inconel 718 alloy with varying degrees of imposed extrusion constraint were carried out. It is found that there is a prominent chip morphology transition from serrated to continuous state and shear band spacing decreases with the constraint degree increasing. In order to uncover underlying mechanism of the imposed extrusion constraint suppressing repeated adiabatic shear banding in DLSEM, new theoretical models are developed where the effects of extrusion constraint, material convection due to chip flow and momentum diffusion during shear band propagation are included. The analytical expressions for the onset criterion of adiabatic shear band and shear band spacing in DLSEM are obtained. The theoretical predictions are in agreement with the experimental results.

  4. Large-scale genomic sequencing of extraintestinal pathogenic Escherichia coli strains

    PubMed Central

    Salipante, Stephen J.; Roach, David J.; Kitzman, Jacob O.; Snyder, Matthew W.; Stackhouse, Bethany; Butler-Wu, Susan M.; Lee, Choli; Cookson, Brad T.

    2015-01-01

    Large-scale bacterial genome sequencing efforts to date have provided limited information on the most prevalent category of disease: sporadically acquired infections caused by common pathogenic bacteria. Here, we performed whole-genome sequencing and de novo assembly of 312 blood- or urine-derived isolates of extraintestinal pathogenic (ExPEC) Escherichia coli, a common agent of sepsis and community-acquired urinary tract infections, obtained during the course of routine clinical care at a single institution. We find that ExPEC E. coli are highly genomically heterogeneous, consistent with pan-genome analyses encompassing the larger species. Investigation of differential virulence factor content and antibiotic resistance phenotypes reveals markedly different profiles among lineages and among strains infecting different body sites. We use high-resolution molecular epidemiology to explore the dynamics of infections at the level of individual patients, including identification of possible person-to-person transmission. Notably, a limited number of discrete lineages caused the majority of bloodstream infections, including one subclone (ST131-H30) responsible for 28% of bacteremic E. coli infections over a 3-yr period. We additionally use a microbial genome-wide-association study (GWAS) approach to identify individual genes responsible for antibiotic resistance, successfully recovering known genes but notably not identifying any novel factors. We anticipate that in the near future, whole-genome sequencing of microorganisms associated with clinical disease will become routine. Our study reveals what kind of information can be obtained from sequencing clinical isolates on a large scale, even well-characterized organisms such as E. coli, and provides insight into how this information might be utilized in a healthcare setting. PMID:25373147

  5. Static FBG strain sensor with high resolution and large dynamic range by dual-comb spectroscopy.

    PubMed

    Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

    2013-05-01

    We demonstrate a fiber Bragg grating (FBG) strain sensor with optical frequency combs. To precisely characterize the optical response of the FBG when strain is applied, dual-comb spectroscopy is used. Highly sensitive dual-comb spectroscopy of the FBG enabled strain measurements with a resolution of 34 nε. The optical spectral bandwidth of the measurement exceeds 1 THz. Compared with conventional FBG strain sensor using a continuous-wave laser that requires rather slow frequency scanning with a limited range, the dynamic range and multiplexing capability are significantly improved by using broadband dual-comb spectroscopy. PMID:23669971

  6. Bulk and Compound-Specific Stable Nitrogen Isotopes in Plankton Reveal Large Impact of Diazotrophy across the Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Mompean de la Rosa, M.; McCarthy, M.; Bode, A.

    2012-12-01

    Enhanced stratification linked to global warming is predicted to decrease nutrient input from deep waters, and may therefore increase oligotrophy in the subtropical ocean. However, nitrogen fixation in many subtropical regions also supports a significant fraction of primary production, a process likely to be enhanced by the same warm/stratified conditions. The shifting balance between major nutrient sources with global change may alter subtropical food webs, possibly strongly affecting the production and export of organic matter. In this study we examined the spatial variability of stable nitrogen isotopes in plankton size fractions in the upper 200 m in a high spatial resolution transect across the Atlantic (24N) during the Malaspina-2010. Our main goal was to determine the major origin of nitrogen for plankton production. Bulk stable isotopes in all size fractions showed a nearly symmetrical spatial distribution, with the lowest values (σ15N <1‰) in the central zone, and were inversely correlated to the abundance of the nitrogen-fixer Trichodesmium. Diazotrophy was estimated to account for >50% of organic nitrogen in the central zone, however it was also very significant (>30%) in eastern and western zones. The relative nitrogen contribution from diazotrophy also increased with increasing plankton size fraction, suggesting the increasing concentration (importance) of recently fixed nitrogen at higher trophic levels, with potential implication for sources of exported organic N. To further explore a possible linkage with trophic position, we also measured compound-specific σ15N values of amino acids, which allowed us to explicitly calculate average trophic position for different plankton size classes. The σ15N value of Phe was then used as direct molecular-level proxy for σ15N value of primary production across the plankton size spectrum. These results indicate that the zone influenced by diazotrophy in the North Atlantic is much larger than reported in

  7. Constitutive Equations and Flow Behavior of an As-Extruded AZ31 Magnesium Alloy Under Large Strain Condition

    NASA Astrophysics Data System (ADS)

    Dong, Yuanyuan; Zhang, Cunsheng; Lu, Xing; Wang, Cuixue; Zhao, Guoqun

    2016-06-01

    A reasonable constitutive model is the key to achieving the accurate numerical simulation of magnesium alloy extrusion process. Based on the hot compression tests of the as-extruded AZ31 magnesium alloy, the strain-compensated Arrhenius equation, the constitutive equation taking into account dynamic recovery (DRV) and dynamic recrystallization (DRX), and the modified Fields-Backofen equation (FB) are established to describe the deformation behavior of this alloy under large strain condition (strain level greater than 1.0) and wide strain rate range (0.01 to 10 s-1), respectively. Then material parameters in each constitutive model are determined by linear fitting method. The comparison of these three kinds of equations shows that the strain-compensated Arrhenius model provides the best prediction of flow stress, and the calculated value of correlation coefficient ( R) is the highest as 0.9945 and the average absolute relative error (AARE) is the lowest as 3.11%. The constitutive equation with DRV + DRX can also predict flow stress accurately, and its values of R and AARE are 0.9920 and 4.41%, respectively. However, compared to the other two constitutive equations, the modified FB equation does not give good description of hot deformation behavior for this magnesium alloy. Finally, the advantages and drawbacks of these three kinds of constitutive models are discussed and compared. Therefore, this work could provide theoretical guidelines for investigating hot deformation behavior of wrought magnesium alloys and determining the appropriate extrusion process parameters under large strain condition.

  8. Constitutive Equations and Flow Behavior of an As-Extruded AZ31 Magnesium Alloy Under Large Strain Condition

    NASA Astrophysics Data System (ADS)

    Dong, Yuanyuan; Zhang, Cunsheng; Lu, Xing; Wang, Cuixue; Zhao, Guoqun

    2016-05-01

    A reasonable constitutive model is the key to achieving the accurate numerical simulation of magnesium alloy extrusion process. Based on the hot compression tests of the as-extruded AZ31 magnesium alloy, the strain-compensated Arrhenius equation, the constitutive equation taking into account dynamic recovery (DRV) and dynamic recrystallization (DRX), and the modified Fields-Backofen equation (FB) are established to describe the deformation behavior of this alloy under large strain condition (strain level greater than 1.0) and wide strain rate range (0.01 to 10 s-1), respectively. Then material parameters in each constitutive model are determined by linear fitting method. The comparison of these three kinds of equations shows that the strain-compensated Arrhenius model provides the best prediction of flow stress, and the calculated value of correlation coefficient (R) is the highest as 0.9945 and the average absolute relative error (AARE) is the lowest as 3.11%. The constitutive equation with DRV + DRX can also predict flow stress accurately, and its values of R and AARE are 0.9920 and 4.41%, respectively. However, compared to the other two constitutive equations, the modified FB equation does not give good description of hot deformation behavior for this magnesium alloy. Finally, the advantages and drawbacks of these three kinds of constitutive models are discussed and compared. Therefore, this work could provide theoretical guidelines for investigating hot deformation behavior of wrought magnesium alloys and determining the appropriate extrusion process parameters under large strain condition.

  9. Very large strain gauges based on single layer MoSe2 and WSe2 for sensing applications

    NASA Astrophysics Data System (ADS)

    Hosseini, Manouchehr; Elahi, Mohammad; Pourfath, Mahdi; Esseni, David

    2015-12-01

    Here, we propose a strain gauge based on single-layer MoSe2 and WSe2 and show that, in these materials, the strain induced modulation of inter-valley phonon scattering leads to large mobility changes, which in turn result in highly sensitive strain gauges. By employing density-functional theory bandstructure calculations, comprehensive scattering models, and the linearized Boltzmann equation, we explain the physical mechanisms for the high sensitivity to strain of the resistivity in single-layer MoSe2 and WSe2, discuss the reduction of the gauge factor produced by extrinsic scattering sources (e.g., chemical impurities), and propose ways to mitigate such sensitivity degradation.

  10. Self-repairing, interferometric waveguide sensor with a large strain range.

    PubMed

    Song, Young J; Peters, Kara J

    2012-10-01

    We demonstrate a polymer waveguide, Fabry-Perot interferometer strain sensor fabricated through a self-writing process in a photopolymerizable resin bath between two silica optical fibers. The measurable strain range is extended through sensor self-repair and strain measurements are demonstrated up to 150% applied tensile strain. The sensor fabrication and repair is performed in the ultraviolet wavelength range, while the sensor interrogation is performed in the near-infrared wavelength range. A hybrid sensor is fabricated by splicing a short segment of multimode optical fiber to the input single-mode optical fiber. The hybrid sensor provides the high quality of waveguide fabrication previously demonstrated through self-writing between multimode optical fibers with the high fringe visibility of single-mode propagation. The peak frequency shift of the reflected spectrum Fabry-Perot sensor is extremely linear with applied strain for the hybrid sensor, with a sensitivity of 2.3×10(-3) per nanometer per percent strain. The calibrated peak frequency shift with applied strain is the same for both the original sensor and the repaired sensor; therefore, the fact that the sensor has self-repaired does not need to be known. Additionally, this calibration is the same between multiple sensor fabrications. In contrast to a conventional air gap Fabry-Perot cavity sensor, no decrease in the fringe visibility is observed over the measurable strain range. PMID:23033107

  11. Oxygen disorder, a way to accommodate large epitaxial strains in oxides

    SciTech Connect

    Zhang, Yu Yang; Mishra, Rohan; Pennycook, Timothy J.; Borisevich, Albina Y.; Pennycook, Stephen J.; Pantelides, Sokrates T.

    2015-09-22

    Density-functional calculations (total-energy comparisons) and checks for negative-frequency phonon modes are employed as a stability indicator to show that, in rutile- and fluorite-structure oxides, e.g., zirconia strained by a strontium titanate substrate, oxygen-sublattice disorder can be the energetically preferred way to accommodate strain.

  12. Flexible and printable paper-based strain sensors for wearable and large-area green electronics.

    PubMed

    Liao, Xinqin; Zhang, Zheng; Liao, Qingliang; Liang, Qijie; Ou, Yang; Xu, Minxuan; Li, Minghua; Zhang, Guangjie; Zhang, Yue

    2016-07-14

    Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control. PMID:27314505

  13. Ultra-High-Strength Interstitial-Free Steel Processed by Equal-Channel Angular Pressing at Large Equivalent Strain

    NASA Astrophysics Data System (ADS)

    Verma, Deepa; Mukhopadhyay, N. K.; Sastry, G. V. S.; Manna, R.

    2016-04-01

    The billets of interstitial-free (IF) steel are deformed by equal-channel angular pressing (ECAP) at 298 K (25 °C) adopting the route BC up to an equivalent strain ( ɛ vm) of 24. The evolution of microstructures and their effects on the mechanical properties are examined. The microstructural refinement involves the elongation of grains, the subdivision of grains to the bands with high dislocation density, and the splitting of bands into the cell blocks and then cell blocks into the cells. The widths of the bands and the size of cells decrease with strain. The degree of reduction in the grain size is highest at the low strain level. However, most of the boundaries at this stage are of low-angle boundaries (at ɛ vm = 3). Thereafter, the misorientation angle increases by progressive lattice rotation with strain. The coarse bands transform step by step from the lamellar structure to the ribbon-shaped grains and finally to the near-equiaxed grain structures with the subgrains of a saturated low-angle grain boundary fraction of 0.34 at very large strain >15. The as-received coarse-grained microstructure (grain size of 57.6 ± 21 µm) has been refined to 257 ± 48 nm at an equivalent strain of 24. The strength increases considerably up to ɛ vm = 3 due to grain refinement and high dislocation density. However, the strengthening at later stages is mainly due to the increase in misorientation angle and refinement. Initial yield strength of 227 MPa is increased to a record value of 895 MPa on straining up to ɛ vm = 24 at 298 K (25 °C). Uniform elongation decreases drastically at low equivalent strain but it regains marginally later. The ECAPed sample fails by a ductile fracture at ɛ vm = 0.6 to 6 but by a mixed mode of ductile-brittle fracture at larger strain of 9 to 24.

  14. Flexible and printable paper-based strain sensors for wearable and large-area green electronics

    NASA Astrophysics Data System (ADS)

    Liao, Xinqin; Zhang, Zheng; Liao, Qingliang; Liang, Qijie; Ou, Yang; Xu, Minxuan; Li, Minghua; Zhang, Guangjie; Zhang, Yue

    2016-06-01

    Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control.Paper-based (PB) green electronics is an emerging and potentially game-changing technology due to ease of recycling/disposal, the economics of manufacture and the applicability to flexible electronics. Herein, new-type printable PB strain sensors (PPBSSs) from graphite glue (graphite powder and methylcellulose) have been fabricated. The graphite glue is exposed to thermal annealing to produce surface micro/nano cracks, which are very sensitive to compressive or tensile strain. The devices exhibit a gauge factor of 804.9, response time of 19.6 ms and strain resolution of 0.038%, all performance indicators attaining and even surpassing most of the recently reported strain sensors. Due to the distinctive sensing properties, flexibility and robustness, the PPBSSs are suitable for monitoring of diverse conditions such as structural strain, vibrational motion, human muscular movements and visual control. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02172g

  15. Sensitivity-Improved Strain Sensor over a Large Range of Temperatures Using an Etched and Regenerated Fiber Bragg Grating

    PubMed Central

    Wang, Yupeng; Qiao, Xueguang; Yang, Hangzhou; Su, Dan; Li, Ling; Guo, Tuan

    2014-01-01

    A sensitivity-improved fiber-optic strain sensor using an etched and regenerated fiber Bragg grating (ER-FBG) suitable for a large range of temperature measurements has been proposed and experimentally demonstrated. The process of chemical etching (from 125 μm to 60 μm) provides regenerated gratings (at a temperature of 680 °C) with a stronger reflective intensity (from 43.7% to 69.8%), together with an improved and linear strain sensitivity (from 0.9 pm/με to 4.5 pm/με) over a large temperature range (from room temperature to 800 °C), making it a useful strain sensor for high temperature environments. PMID:25299954

  16. Large-scale assembly of highly sensitive Si-based flexible strain sensors for human motion monitoring.

    PubMed

    Zhang, Bing-Chang; Wang, Hui; Zhao, Yu; Li, Fan; Ou, Xue-Mei; Sun, Bao-Quan; Zhang, Xiao-Hong

    2016-01-28

    Silicon is the dominant semiconductor in modern society, but the rigid nature of most Si structures hinders its applications in flexible electronics. In this work, Si-based flexible strain sensors are fabricated with Si fabric consisting of long Si nanowires. The as-obtained sensors demonstrate a large strain range of 50% and a gauge factor of up to 350, which are sufficient to detect human motions with superior performance over traditional sensors. The results reveal that the assembling strategy may potentially be applied to large-scale fabrication of highly sensitive, flexible strain sensors for emerging applications such as healthcare and sports monitoring. Moreover, the Si fabric would also enable broad applications of Si materials in other flexible and wearable devices such as flexible optoelectronics and displays. PMID:26725832

  17. Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

    PubMed

    Pirotte, Geert; Kesters, Jurgen; Verstappen, Pieter; Govaerts, Sanne; Manca, Jean; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter

    2015-10-12

    Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool. In this contribution, a flow protocol is optimized for the high performance benzodithiophene-thienopyrroledione copolymer PBDTTPD and the material quality is probed through systematic solar-cell evaluation. A stepwise approach is adopted to turn the batch process into a reproducible and scalable continuous flow procedure. Solar cell devices fabricated using the obtained polymer batches deliver an average power conversion efficiency of 7.2 %. Upon incorporation of an ionic polythiophene-based cathodic interlayer, the photovoltaic performance could be enhanced to a maximum efficiency of 9.1 %. PMID:26388210

  18. Draft Genome Sequence of Rheinheimera sp. F8, a Biofilm-Forming Strain Which Produces Large Amounts of Extracellular DNA

    PubMed Central

    Szewzyk, Ulrich

    2016-01-01

    Rheinheimera sp. strain F8 is a biofilm-forming gammaproteobacterium that has been found to produce large amounts of filamentous extracellular DNA. Here, we announce the de novo assembly of its genome. It is estimated to be 4,464,511 bp in length, with 3,970 protein-coding sequences and 92 RNA-coding sequences. PMID:26966195

  19. Strength and flexibility of bulk high-T{sub c} superconductors.

    SciTech Connect

    Goretta, K. C.; Jiang, M.; Kupperman, D. S.; Lanagan, M. T.; Singh, J. P.; Vasanthamohan, N.; Hinks, D. G.; Mitchell, J. F.; Richardson, J. W., Jr.

    1997-06-01

    Strength, fracture toughness, and elastic modulus data for bulk high-temperature superconductors, commercial 99.9% Ag, and a 1.2 at.% Mg/Ag alloy have been collected. These data have been used to calculate fracture strains for bulk conductors. The calculations indicate that the superconducting cores of clad tapes should begin to fracture at strains below 0.2%. In addition, residual strains in Ag-clad (Bi,Pb)2Sr2Ca2Cu3Ox tapes have been measured by neutron diffraction. An explanation is offered for why many tapes appear to be able to tolerate large strains before exhibiting a reduction in current transport.

  20. Large physisorption strain and edge modification of Pd on monolayer graphene

    NASA Astrophysics Data System (ADS)

    Zhou, Haiqing; Yu, Fang; Tang, Dongsheng; Chen, Minjiang; Yang, Huaichao; Wang, Gang; Guo, Yanjun; Sun, Lianfeng

    2012-12-01

    Using Raman spectroscopic studies, we firstly report that Pd film deposition can induce a tensile strain at the interface between Pd and n-layer graphenes, which results in the splitting of the G peak and a red Raman shift of the 2D peak in monolayer graphene, and red Raman shifts of G and 2D peaks for other n-layer graphenes. In particular, this kind of tensile strain can be used as an effective way for edge modification or strain engineering in monolayer graphene.

  1. An experimentally verified finite element study of the stress-strain response of crack geometries experiencing large-scale yielding

    SciTech Connect

    Panontin, T.L.; Sheppard, S.D.

    1997-12-01

    Large-strain, 3-D finite element analyses with incremental plasticity were performed for a variety of crack geometries to study local crack-tip stress-strain fields and associated global fracture parameters under conditions of large-scale yielding. The geometries analyzed include thin, single-edge crack tension, single-edge crack bending, and center-crack tension fracture specimens with varying crack depth (a/W) ratios. Two materials were investigated: a high-hardening, low-strength steel and a moderate-hardening, high-strength steel. Mesh refinement studies were performed to ensure convergence of the finite element predictions. The studies examine the effects of in-plane crack-tip element size, initial crack-tip radius size, and number of through-thickness layers on predicted distributions of crack-tip stress and plastic strain and predicted values of the J-integral and CTOD. In addition, the finite element predictions of specimen behavior were verified experimentally by direct measurements, namely load displacement, load longitudinal strain, and load CTOS, made during and following testing of the fracture specimens. Representative results of the finite element analyses are presented and compared to previously published data where pertinent. Results from the mesh refinement studies and the verification testing are shown. Predicted trends among the specimens and materials in local distributions of crack-tip plastic strain, triaxiality, and opening stress as well as in global parameters, J-integral and m-factor, are discussed.

  2. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

    SciTech Connect

    Hegde, Ganesh Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

    2014-03-28

    The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

  3. The choice of strain gage for use in a large superconducting alternator

    SciTech Connect

    Ferrero, C.; Desogus, S.

    1982-01-01

    Electrical strain gages are investigated from ambient to liquid-helium temperatures. Experimental determination of the curves of apparent strain vs. temperature were especially considered, because of the role of thermal and mechanical stresses in a superconducting rotor in the cooling and operational phases. Commercially available Karma and modified-Karma alloy foil strain gages were used. These were either applied on the surface of supports of Cu, Al, Incar, AISI 304L, Araldite, and Nb, or embedded inside the specimen. Results are analyzed in terms of 4.2 to 7.2 range, 4.2 to 30 K range, reversal temperature, behavior with strain, and power dissipation effects. Conclusions are formulated with proposed applications to a wide range of technological items which require stress measurement and control in a narrow temperature range near 4.2 K.

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

    PubMed

    Lévesque, Simon; Plante, Pier-Luc; Mendis, Nilmini; Cantin, Philippe; Marchand, Geneviève; Charest, Hugues; Raymond, Frédéric; Huot, Caroline; Goupil-Sormany, Isabelle; Desbiens, François; Faucher, Sébastien P; Corbeil, Jacques; Tremblay, Cécile

    2014-01-01

    During the summer of 2012, a major Legionella pneumophila serogroup 1 outbreak occurred in Quebec City, Canada, which caused 182 declared cases of Legionnaire's disease and included 13 fatalities. Legionella pneumophila serogroup 1 isolates from 23 patients as well as from 32 cooling towers located in the vicinity of the outbreak were recovered for analysis. In addition, 6 isolates from the 1996 Quebec City outbreak and 4 isolates from patients unrelated to both outbreaks were added to allow comparison. We characterized the isolates using pulsed-field gel electrophoresis, sequence-based typing, and whole genome sequencing. The comparison of patients-isolated strains to cooling tower isolates allowed the identification of the tower that was the source of the outbreak. Legionella pneumophila strain Quebec 2012 was identified as a ST-62 by sequence-based typing methodology. Two new Legionellaceae plasmids were found only in the epidemic strain. The LVH type IV secretion system was found in the 2012 outbreak isolates but not in the ones from the 1996 outbreak and only in half of the contemporary human isolates. The epidemic strains replicated more efficiently and were more cytotoxic to human macrophages than the environmental strains tested. At least four Icm/Dot effectors in the epidemic strains were absent in the environmental strains suggesting that some effectors could impact the intracellular replication in human macrophages. Sequence-based typing and pulsed-field gel electrophoresis combined with whole genome sequencing allowed the identification and the analysis of the causative strain including its likely environmental source. PMID:25105285

  5. Large and Uniform Optical Emission Shifts in Quantum Dots Strained along Their Growth Axis

    NASA Astrophysics Data System (ADS)

    Stepanov, Petr; Elzo-Aizarna, Marta; Bleuse, Joël; Malik, Nitin S.; Curé, Yoann; Gautier, Eric; Favre-Nicolin, Vincent; Gérard, Jean-Michel; Claudon, Julien

    2016-05-01

    We introduce a method which enables to directly compare the impact of elastic strain on the optical properties of distinct quantum dots (QDs). Specifically, the QDs are integrated in a cross-section of a semiconductor core wire which is surrounded by an amorphous straining shell. Detailed numerical simulations show that, thanks to the mechanical isotropy of the shell, the strain field in a core section is homogeneous. Furthermore, we use the core material as an in situ strain gauge, yielding reliable values for the emitter energy tuning slope. This calibration technique is applied to self-assembled InAs QDs submitted to incremental tensile strain along their growth axis. In contrast to recent studies conducted on similar QDs stressed perpendicularly to their growth axis, optical spectroscopy reveals 5-10 times larger tuning slopes, with a moderate dispersion. These results highlight the importance of the stress direction to optimise QD response to applied strain, with implications both in static and dynamic regimes. As such, they are in particular relevant for the development of wavelength-tunable single photon sources or hybrid QD opto-mechanical systems.

  6. Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y-Ba-Cu-O superconductor

    NASA Astrophysics Data System (ADS)

    Philippe, M. P.; Ainslie, M. D.; Wéra, L.; Fagnard, J.-F.; Dennis, A. R.; Shi, Y.-H.; Cardwell, D. A.; Vanderheyden, B.; Vanderbemden, P.

    2015-09-01

    Bulk, high temperature superconductors have significant potential for use as powerful permanent magnets in a variety of practical applications due to their ability to trap record magnetic fields. In this paper, soft ferromagnetic sections are combined with a bulk, large grain Y-Ba-Cu-O high temperature superconductor to form superconductor/ferromagnet hybrid structures. We study how the ferromagnetic sections influence the shape of the profile of the trapped magnetic induction at the surface of each structure and report the surface magnetic flux density measured by Hall probe mapping. These configurations have been modelled using a 2D axisymmetric finite element method based on the H -formulation and the results show excellent qualitative and quantitative agreement with the experimental measurements. The model has also been used to study the magnetic flux distribution and predict the behaviour for other constitutive laws and geometries. The results show that the ferromagnetic material acts as a magnetic shield, but the flux density and its gradient are enhanced on the face opposite to the ferromagnet. The thickness and saturation magnetization of the ferromagnetic material are important and a characteristic ferromagnet thickness d* is derived: below d*, saturation of the ferromagnet occurs, and above d*, a weak thickness-dependence is observed. The influence of the ferromagnet is observed even if its saturation magnetization is lower than the trapped flux density of the superconductor. Conversely, thin ferromagnetic discs can be driven to full saturation even though the outer magnetic field is much smaller than their saturation magnetization.

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

    SciTech Connect

    Challacombe, Jean F; Eichorst, Stephanie A; Xie, Gary; Kuske, Cheryl R; Hauser, Loren; Land, Miriam

    2009-01-01

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

  8. Recrystallization and the Development of Abnormally Large Grains After Small Strain Deformation in a Polycrystalline Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Miller, Victoria M.; Johnson, Anthony E.; Torbet, Chris J.; Pollock, Tresa M.

    2016-04-01

    The formation of abnormally large grains has been investigated in the polycrystalline nickel-based superalloy René 88DT. Cylindrical specimens with a 15 μm grain size were compressed to plastic strains up to 11.0 pct and subsequently rapidly heated to above the γ' solvus at 1423 K (1150° C) and held for 60 seconds. All deformed samples partially recrystallized during the heat treatment, with the recrystallized grain size varying with the degree of deformation. The largest final grain size occurred in samples deformed to approximately 2 pct strain, with isolated grains as large as 700 μm in diameter observed. It is proposed that abnormally large grains appear due to nucleation-limited recrystallization, not abnormal grain growth, based on the high boundary velocities measured and the observed reduction in grain orientation spread.

  9. K and Mn co-doped BaCd2As2: A hexagonal structured bulk diluted magnetic semiconductor with large magnetoresistance

    NASA Astrophysics Data System (ADS)

    Yang, Xiaojun; Li, Yuke; Zhang, Pan; Jiang, Hao; Luo, Yongkang; Chen, Qian; Feng, Chunmu; Cao, Chao; Dai, Jianhui; Tao, Qian; Cao, Guanghan; Xu, Zhu-An

    2013-12-01

    A bulk diluted magnetic semiconductor was found in the K and Mn co-doped BaCd2As2 system. Different from recently reported tetragonal ThCr2Si2-structured II-II-V based (Ba,K)(Zn,Mn)2As2, the Ba1-yKyCd2-xMnxAs2 system has a hexagonal CaAl2Si2-type structure with the Cd2As2 layer forming a honeycomb-like network. The Mn concentration reaches up to x ˜ 0.4. Magnetization measurements show that the samples undergo ferromagnetic transitions with Curie temperature up to 16 K. With low coercive field of less than 10 Oe and large magnetoresistance of about -70%, the hexagonal structured Ba1-yKyCd2-xMnxAs2 can be served as a promising candidate for spin manipulations.

  10. Design of collective Thomson scattering system using 77 GHz gyrotron for bulk and tail ion diagnostics in the large helical device

    SciTech Connect

    Nishiura, M.; Tanaka, K.; Kubo, S.; Kawahata, K.; Shimozuma, T.; Mutoh, T.; Saito, T.; Tatematsu, Y.; Notake, T.

    2008-10-15

    Collective Thomson scattering (CTS) system is expected to be a strong diagnostic tool for measuring thermal and fast ion distribution function at a local point inside plasmas. The electron cyclotron resonance heating system using a gyrotron at the frequency range of 77 GHz has been installed at the large helical device (LHD). The feasibility of CTS system using the 77 GHz gyrotron is assessed in terms of scattering spectrum and a background noise of the electron cyclotron emission, which affect the signal to noise ratio, with the realistic plasma parameters and incident port locations of LHD. Based on the calculated scattering spectra for bulk and tail fast ion diagnostics, the scattering radiation receiver system with gyrotron frequency feedback circuit is proposed to avoid the frequency chirping.

  11. Design of collective Thomson scattering system using 77 GHz gyrotron for bulk and tail ion diagnostics in the large helical device.

    PubMed

    Nishiura, M; Tanaka, K; Kubo, S; Saito, T; Tatematsu, Y; Notake, T; Kawahata, K; Shimozuma, T; Mutoh, T

    2008-10-01

    Collective Thomson scattering (CTS) system is expected to be a strong diagnostic tool for measuring thermal and fast ion distribution function at a local point inside plasmas. The electron cyclotron resonance heating system using a gyrotron at the frequency range of 77 GHz has been installed at the large helical device (LHD). The feasibility of CTS system using the 77 GHz gyrotron is assessed in terms of scattering spectrum and a background noise of the electron cyclotron emission, which affect the signal to noise ratio, with the realistic plasma parameters and incident port locations of LHD. Based on the calculated scattering spectra for bulk and tail fast ion diagnostics, the scattering radiation receiver system with gyrotron frequency feedback circuit is proposed to avoid the frequency chirping. PMID:19044547

  12. An efficient numerical method for predicting the evolution of internal variables and springback in bending under tension at large strains

    NASA Astrophysics Data System (ADS)

    Alexandrov, Sergei; Jeng, Yeau-Ren

    2013-12-01

    Quite a general elastic/plastic material model including evolution equations for internal variables is adopted to predict the distribution of material properties and springback in plane strain bending under tension at large strains. A transformation equation to connect Lagrangian and Eulerian coordinates is used to reduce the original boundary value problem to a system of hyperbolic equations. This system is then solved by the method of characteristics combined with a finite difference scheme. In a particular case of elastic/plastic hardening materials (in this case the only internal variable is the equivalent plastic strain) an analytic solution is available in the literature. Using this solution it is demonstrated that the accuracy of the numerical method is very high.

  13. Large scale analysis of virulence genes in Escherichia coli strains isolated from Avalon Bay, CA.

    PubMed

    Hamilton, Matthew J; Hadi, Asbah Z; Griffith, John F; Ishii, Satoshi; Sadowsky, Michael J

    2010-10-01

    Contamination of recreational waters with Escherichia coli and Enterococcus sp. is a widespread problem resulting in beach closures and loss of recreational activity. While E. coli is frequently used as an indicator of fecal contamination, and has been extensively measured in waterways, few studies have examined the presence of potentially pathogenic E. coli strains in beach waters. In this study, a combination of high-throughput, robot-assisted colony hybridization and PCR-based analyses were used to determine the genomic composition and frequency of virulence genes present in E. coli isolated from beach water in Avalon Bay, Santa Catalina Island, CA. A total of 24,493 E. coli isolates were collected from two sites at a popular swimming beach between August through September 2007 and from July through August 2008. All isolates were examined for the presence of shiga-like toxins (stx1/stx2), intimin (eaeA), and enterotoxins (ST/LT). Of the 24,493 isolates examined, 3.6% contained the eaeA gene, indicating that these isolates were potential EPEC strains. On five dates, however, greater than 10% of the strains were potential EPEC, suggesting that incidence of virulence genes at this beach has a strong temporal component. No STEC or ETEC isolates were detected, and only eight (<1.0%) of the potential EPEC isolates were found to carry the EAF plasmid. The potential EPEC isolates mainly belonged to E. coli phylogenetic groups B1 or B2, and carried the β intimin subtype. DNA fingerprint analyses of the potential EPEC strains indicated that the isolates belonged to several genetically diverse groups, although clonal isolates were frequently detected. While the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potential EPEC strains can be found in marine beach water and their presence needs to be considered as one of the factors used in decisions concerning beach closures. PMID:20643468

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  15. Strength and flexibility of bulk high-{Tc} superconductors

    SciTech Connect

    Goretta, K.C.; Jiang, M.; Kupperman, D.S.; Lanagan, M.T.; Singh, J.P.; Vasanthamohan, N.; Hinks, D.G.; Mitchell, J.F.; Richardson, J.W. Jr.

    1996-08-01

    Strength, fracture toughness, and elastic modulus data have been gathered for bulk high-temperature superconductors, commercial 99.9% Ag, and a 1.2 at.% Mg/Ag alloy. These data have been used to calculate fracture strains for bulk conductors. The calculations indicate that the superconducting cores of clad tapes should begin to fracture at strains below 0.2%. In addition, residual strains in Ag-clad (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} tapes have been measured by neutron diffraction. An explanation is offered for why many tapes appear to be able to tolerate large strains before exhibiting a reduction in current transport.

  16. Large-strain, multiform movements from designable electrothermal actuators based on large highly anisotropic carbon nanotube sheets.

    PubMed

    Li, Qingwei; Liu, Changhong; Lin, Yuan-Hua; Liu, Liang; Jiang, Kaili; Fan, Shoushan

    2015-01-27

    Many electroactive polymer (EAP) actuators use diverse configurations of carbon nanotubes (CNTs) as pliable electrodes to realize discontinuous, agile movements, for CNTs are conductive and flexible. However, the reported CNT-based EAP actuators could only accomplish simple, monotonous actions. Few actuators were extended to complex devices because efficiently preparing a large-area CNT electrode was difficult, and complex electrode design has not been carried out. In this work, we successfully prepared large-area CNT paper (buckypaper, BP) through an efficient approach. The BP is highly anisotropic, strong, and suitable as flexible electrodes. By means of artful graphic design and processing on BP, we fabricated various functional BP electrodes and developed a series of BP-polymer electrothermal actuators (ETAs). The prepared ETAs can realize various controllable movements, such as large-stain bending (>180°), helical curling (∼ 630°), or even bionic actuations (imitating human-hand actions). These functional and interesting movements benefit from flexible electrode design and the anisotropy of BP material. Owing to the advantages of low driving voltage (20-200 V), electrolyte-free and long service life (over 10000 times), we think the ETAs will have great potential applications in the actuator field. PMID:25559661

  17. Crystal plasticity based finite element modelling of large strain deformation in AM30 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Izadbakhsh, Adel; Inal, Kaan; Mishra, Raja K.

    2012-04-01

    In this paper, the finite strain plastic deformation of AM30 magnesium alloy has been simulated using the crystal plasticity finite element method. The simulations have been carried out using a rate-dependent elastic-viscoplastic crystal plasticity constitutive model implemented in a user defined material subroutine (UMAT) in the commercial software LS-DYNA. The plastic deformation mechanisms accounted for in the model are the slip systems in the matrix (parent grain), extension twinning systems and the slip systems inside the extension twinned regions. The parameters of the constitutive model have been calibrated using the experimental data. The calibrated model has then been used to predict the deformation of AM30 magnesium alloy in bending and simple shear. For the bending strain path, the effects of texture on the strain accommodated by the deformation mechanisms and bending moment have been investigated. For simple shear, the effects of texture on the relative activity of deformation mechanisms, shear stress and texture evolution have been investigated. Also, the effect of twinning on shear stress and texture evolution has been studied. The numerical analyses predicted a more uniform strain distribution during bending and simple shear for rolled texture compared with extruded texture.

  18. Large scale parallel pyrosequencing technology: PRRSV strain VR-2332 nsp2 deletion mutant stability in swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomes from fifteen porcine reproductive and respiratory syndrome virus (PRRSV) isolates were derived simultaneously using 454 pyrosequencing technology. The viral isolates sequenced were from a recent swine study, in which engineered Type 2 prototype PRRSV strain VR-2332 mutants, with 87, 184, 200...

  19. Differential segmental strain during active lengthening in a large biarticular thigh muscle during running

    PubMed Central

    Carr, Jennifer A.; Ellerby, David J.; Marsh, Richard L.

    2011-01-01

    SUMMARY The iliotibialis lateralis pars postacetabularis (ILPO) is the largest muscle in the hindlimb of the guinea fowl and is thought to play an important role during the stance phase of running, both absorbing and producing work. Using sonomicrometry and electromyography, we examined whether the ILPO experiences differential strain between proximal, central and distal portions of the posterior fascicles. When the ILPO is being lengthened while active, the distal portion was found to lengthen significantly more than either the proximal or central portions of the muscle. Our data support the hypothesis that the distal segment lengthened farther and faster because it began activity at shorter sarcomere lengths on the ascending limb of the length–tension curve. Probably because of the self-stabilizing effects of operating on the ascending limb of the length–tension curve, all segments reached the end of lengthening and started shortening at the same sarcomere length. During shortening, this similarity in sarcomere length among the segments was maintained, as predicted from force–velocity effects, and shortening strain was similar in all segments. The differential active strain during active lengthening is thus ultimately determined by differences in strain during the passive portion of the cycle. The sarcomere lengths of all segments of the fascicles were similar at the end of active shortening, but after the passive portion of the cycle the distal segment was shorter. Differential strain in the segments during the passive portion of the cycle may be caused by differential joint excursions at the knee and hip acting on the ends of the muscle and being transmitted differentially by the passive visco-elastic properties of the muscle. Alternatively, the differential passive strain could be due to the action of active or passive muscles in the thigh that transmit force to the IPLO in shear. Based on basic sarcomere dynamics we predict that differential strain is

  20. Computational strategy for the solution of large strain nonlinear problems using the Wilkins explicit finite-difference approach

    NASA Technical Reports Server (NTRS)

    Hofmann, R.

    1980-01-01

    The STEALTH code system, which solves large strain, nonlinear continuum mechanics problems, was rigorously structured in both overall design and programming standards. The design is based on the theoretical elements of analysis while the programming standards attempt to establish a parallelism between physical theory, programming structure, and documentation. These features have made it easy to maintain, modify, and transport the codes. It has also guaranteed users a high level of quality control and quality assurance.

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

    PubMed

    van Opijnen, Tim; Dedrick, Sandra; Bento, José

    2016-09-01

    The interaction between an antibiotic and bacterium is not merely restricted to the drug and its direct target, rather antibiotic induced stress seems to resonate through the bacterium, creating selective pressures that drive the emergence of adaptive mutations not only in the direct target, but in genes involved in many different fundamental processes as well. Surprisingly, it has been shown that adaptive mutations do not necessarily have the same effect in all species, indicating that the genetic background influences how phenotypes are manifested. However, to what extent the genetic background affects the manner in which a bacterium experiences antibiotic stress, and how this stress is processed is unclear. Here we employ the genome-wide tool Tn-Seq to construct daptomycin-sensitivity profiles for two strains of the bacterial pathogen Streptococcus pneumoniae. Remarkably, over half of the genes that are important for dealing with antibiotic-induced stress in one strain are dispensable in another. By confirming over 100 genotype-phenotype relationships, probing potassium-loss, employing genetic interaction mapping as well as temporal gene-expression experiments we reveal genome-wide conditionally important/essential genes, we discover roles for genes with unknown function, and uncover parts of the antibiotic's mode-of-action. Moreover, by mapping the underlying genomic network for two query genes we encounter little conservation in network connectivity between strains as well as profound differences in regulatory relationships. Our approach uniquely enables genome-wide fitness comparisons across strains, facilitating the discovery that antibiotic responses are complex events that can vary widely between strains, which suggests that in some cases the emergence of resistance could be strain specific and at least for species with a large pan-genome less predictable. PMID:27607357

  2. Strain modulated large magnetocaloric effect in Sm0.55Sr0.45MnO3 epitaxial films

    NASA Astrophysics Data System (ADS)

    Giri, S. K.; Dasgupta, Papri; Poddar, A.; Sahoo, R. C.; Paladhi, D.; Nath, T. K.

    2015-01-01

    Epitaxial Sm0.55Sr0.45MnO3 thin films were deposited on LAO (001), LSAT (001), and STO (001) single crystalline substrates by pulsed laser deposition technique to investigate the correlation between the substrate induced film lattice strain and magnetocaloric effect (MCE). The film on LAO substrate (S_LAO), which is under compressive strain, undergoes ferromagnetic → paramagnetic transition at TC ˜ 165 K. The films on STO (S_STO) and LSAT (S_LSAT) substrates are under tensile strain and have TC ˜ 120 K and 130 K, respectively. At T < TC, the zero field cooled and field cooled magnetization curves of all the films show huge bifurcation. In case of S_STO and S_LSAT films, hysteresis is also observed between field cooled cooling and warming cycle in magnetization versus temperature measurement at low magnetic field similar to first order-like magnetic phase transition. No signature of first order magnetic phase transition has been observed in the case of S_LAO film. Most interestingly, both normal (i.e., negative ΔSM) and inverse (i.e., positive ΔSM) MCE around TC and above Tp, respectively, for S_STO and S_LSAT films have been observed with maximum value of MCE ˜ 10 J kg-1 K-1. The S_STO film also exhibits a large relative cooling power of 142 J/kg for a magnetic field change of 1 T. Our findings of substrate-induced strain modulated large MCE in epitaxial Sm0.55Sr0.45MnO3 films have been well explained through the substrate induced film lattice strain, and it may be useful for active magnetic refrigerant materials.

  3. Large and Uniform Optical Emission Shifts in Quantum Dots Strained along Their Growth Axis.

    PubMed

    Stepanov, Petr; Elzo-Aizarna, Marta; Bleuse, Joël; Malik, Nitin S; Curé, Yoann; Gautier, Eric; Favre-Nicolin, Vincent; Gérard, Jean-Michel; Claudon, Julien

    2016-05-11

    We introduce a calibration method to quantify the impact of external mechanical stress on the emission wavelength of distinct quantum dots (QDs). Specifically, these emitters are integrated in a cross-section of a semiconductor core wire and experience a longitudinal strain that is induced by an amorphous capping shell. Detailed numerical simulations show that, thanks to the shell mechanical isotropy, the strain in the core is uniform, which enables a direct comparison of the QD responses. Moreover, the core strain is determined in situ by an optical measurement, yielding reliable values for the QD emission tuning slope. This calibration technique is applied to self-assembled InAs QDs submitted to incremental elongation along their growth axis. In contrast to recent studies conducted on similar QDs submitted to a uniaxial stress perpendicular to the growth direction, optical spectroscopy reveals up to ten times larger tuning slopes, with a moderate dispersion. These results highlight the importance of the stress direction to optimize the QD optical shift, with general implications, both in static and dynamic regimes. As such, they are in particular relevant for the development of wavelength-tunable single-photon sources or hybrid QD opto-mechanical systems. PMID:27058255

  4. Strain-Rate Dependence of Material Strength: Large-Scale Atomistic Simulations of Defective Cu and Ta Crystals

    NASA Astrophysics Data System (ADS)

    Abeywardhana, M.; Vasquez, A.; Gaglione, J.; Germann, T. C.; Ravelo, R.

    2015-06-01

    Large-Scale molecular dynamics (MD) simulations are used to model shock wave (SW) and quasi-isentropic compression (QIC) in defective copper and tantalum crystals. The atomic interactions were modeled employing embedded-atom method (EAM) potentials. In the QIC simulations, the MD equations of motion are modified by incorporating a collective strain rate function in the positions and velocities equations, so that the change in internal energy equals the PV work on the system. We examined the deformation mechanisms and material strength for strain rates in the 109-1012 s-1 range For both Cu and Ta defective crystals, we find that the strain rate dependence of the flow stress in this strain rate regime, follows a power law with an exponent close to 0.40. This work was supported by the Air Force Office of Scientific Research under AFOSR Award No. FA9550-12-1-0476. Work at Los Alamos was performed under the auspices of the U.S. Department of Energy (DOE) under Contract No. DE-AC52-06NA25396.

  5. Large zeolite H-ZSM-5 crystals as models for the methanol-to-hydrocarbons process: bridging the gap between single-particle examination and bulk catalyst analysis.

    PubMed

    Hofmann, Jan P; Mores, Davide; Aramburo, Luis R; Teketel, Shewangizaw; Rohnke, Marcus; Janek, Jürgen; Olsbye, Unni; Weckhuysen, Bert M

    2013-06-24

    The catalytic, deactivation, and regeneration characteristics of large coffin-shaped H-ZSM-5 crystals were investigated during the methanol-to-hydrocarbons (MTH) reaction at 350 and 500 °C. Online gas-phase effluent analysis and examination of retained material thereof were used to explore the bulk properties of large coffin-shaped zeolite H-ZSM-5 crystals in a fixed-bed reactor to introduce them as model catalysts for the MTH reaction. These findings were related to observations made at the individual particle level by using polarization-dependent UV-visible microspectroscopy and mass spectrometric techniques after reaction in an in situ microspectroscopy reaction cell. Excellent agreement between the spectroscopic measurements and the analysis of hydrocarbon deposits by means of retained hydrocarbon analysis and time-of-flight secondary-ion mass spectrometry of spent catalyst materials was observed. The obtained data reveal a shift towards more condensed coke deposits on the outer zeolite surface at higher reaction temperatures. Zeolites in the fixed-bed reactor setup underwent more coke deposition than those reacted in the in situ microspectroscopy reaction cell. Regeneration studies of the large zeolite crystals were performed by oxidation in O2 /inert gas mixtures at 550 °C. UV-visible microspectroscopic measurements using the oligomerization of styrene derivatives as probe reaction indicated that the fraction of strong acid sites decreased during regeneration. This change was accompanied by a slight decrease in the initial conversion obtained after regeneration. H-ZSM-5 deactivated more rapidly at higher reaction temperature. PMID:23649944

  6. Flow Curve Determination at Large Plastic Strain Levels to Accurately Constitutive Equations of AHSS in Forming Simulation

    NASA Astrophysics Data System (ADS)

    Lemoine, X.; Sriram, S.; Kergen, R.

    2011-05-01

    ArcelorMittal continuously develops new steel grades (AHSS) with high performance for the automotive industry to improve the weight reduction and the passive safety. The wide market introduction of AHSS raises a new challenge for manufacturers in terms of material models in the prediction of forming—especially formability and springback. The relatively low uniform elongation, the high UTS and the low forming limit curve of these AHSS may cause difficulties in forming simulations. One of these difficulties is the consequence of the relatively low uniform elongation on the parameters identification of isotropic hardening model. Different experimental tests allow to reach large plastic strain levels (hydraulic bulge test, stack compression test, shear test…). After a description on how to determine the flow curve in these experimental tests, a comparison of the different flow curves is made for different steel grades. The ArcelorMittal identification protocol for hardening models is only based on stress-strain curves determined in uniaxial tension. Experimental tests where large plastic strain levels are reached are used to validate our identification protocol and to recommend some hardening models. Finally, the influence of isotropic hardening models and yield loci in forming prediction for AHSS steels will be presented.

  7. Identification and characterization of large-effect quantitative trait loci for grain yield under lowland drought stress in rice using bulk-segregant analysis.

    PubMed

    Venuprasad, Ramaiah; Dalid, C O; Del Valle, M; Zhao, D; Espiritu, M; Sta Cruz, M T; Amante, M; Kumar, A; Atlin, G N

    2009-12-01

    An F(4:5) population of 490 recombinant inbred lines (RILs) from the cross Apo/(2*)Swarna was used to detect quantitative trait loci (QTL) with large effects on grain yield under drought stress using bulk-segregant analysis (BSA). Swarna is an important rainfed lowland rice variety grown on millions of hectares in Asia, but is highly susceptible to drought and aerobic soil conditions. Apo is an aerobic-adapted variety with moderate tolerance to drought. Two rice microsatellite (RM) markers, RM324, and RM416, located on chromosomes 2 and 3, respectively, were shown via BSA to be strongly associated with yield under lowland drought stress. The effects of these QTL were tested in a total of eight hydrological environments over a period of 3 years. The QTL linked to RM416 (DTY(3.1)) had a large effect on grain yield under severe lowland drought stress, explaining about 31% of genetic variance for the trait (P < 0.0001). It also explained considerable variance for yield under mild stress in lowland conditions and aerobic environments. To our knowledge this is the first reported QTL that has a large effect on yield in both lowland drought and aerobic environments. The QTL linked to RM324 (DTY(2.1)) had a highly significant effect on grain yield in lowland drought stress (R(2) = 13-16%) and in two aerobic trials. The effect of these QTL on grain yield was verified to be not mainly due to phenology differences. Effects of DTY(3.1) on yield under stress have been observed in several other rice mapping populations studied at IRRI. Results of this study indicate that BSA is an effective method of identifying QTL alleles with large effects on rice yield under severe drought stress. The Apo alleles for these large-effect QTL for grain yield under drought and aerobic conditions may be immediately exploited in marker-assisted-breeding to improve the drought tolerance of Swarna. PMID:19841886

  8. Measuring strain distributions in amorphous materials

    NASA Astrophysics Data System (ADS)

    Poulsen, Henning F.; Wert, John A.; Neuefeind, Jörg; Honkimäki, Veijo; Daymond, Mark

    2005-01-01

    A number of properties of amorphous materials including fatigue, fracture and component performance are governed by the magnitude of strain fields around inhomogeneities such as inclusions, voids and cracks. At present, localized strain information is only available from surface probes such as optical or electron microscopy. This is unfortunate because surface and bulk characteristics in general differ. Hence, to a large extent, the assessment of strain distributions relies on untested models. Here we present a universal diffraction method for characterizing bulk stress and strain fields in amorphous materials and demonstrate its efficacy by work on a material of current interest in materials engineering: a bulk metallic glass. The macroscopic response is shown to be less stiff than the atomic next-neighbour bonds because of structural rearrangements at the scale of 4-10 Å. The method is also applicable to composites comprising an amorphous matrix and crystalline inclusions.

  9. Large-magnitude transient strain accumulation on the Blackwater fault, Eastern California shear zone

    NASA Astrophysics Data System (ADS)

    Oskin, Michael; Iriondo, Alex

    2004-04-01

    We investigate the Quaternary slip rate for the Blackwater fault, Eastern California shear zone, through mapping and geochronology of offset volcanic rocks. Basalt flows of the Black Mountains support the presence of faulting at 3.77 ± 0.11 Ma, 1.8 ± 0.1 km of subsequent slip, and a well-constrained long-term slip rate of 0.49 ± 0.04 mm/yr. Total slip diminishes northward, evidenced by a 0.3 1.8 km offset of a 7.23 ± 1.07 Ma dacite flow in the Black Hills and fault termination in the Lava Mountains, 5 km short of the Garlock fault. Slow long-term slip rate together with sparse evidence for Holocene rupture contradict predictions of rapid slip rate from tectonic geodesy. These results support the conclusion that as much as 95% of geodetic strain accumulation across the Blackwater fault, and thus from 1 to 6 mm/yr of geodetic strain measured across the Eastern California shear zone, is a transitory phenomenon. Discrepant geologic and geodetic results may indicate an increased near-term seismic hazard, but merit caution for interpretation of fault slip rates from geodesy alone.

  10. Shared Genomic Regions Between Derivatives of a Large Segregating Population of Maize Identified Using Bulked Segregant Analysis Sequencing and Traditional Linkage Analysis

    PubMed Central

    Haase, Nicholas J.; Beissinger, Timothy; Hirsch, Candice N.; Vaillancourt, Brieanne; Deshpande, Shweta; Barry, Kerrie; Buell, C. Robin; Kaeppler, Shawn M.; de Leon, Natalia

    2015-01-01

    Delayed transition from the vegetative stage to the reproductive stage of development and increased plant height have been shown to increase biomass productivity in grasses. The goal of this project was to detect quantitative trait loci using extremes from a large synthetic population, as well as a related recombinant inbred line mapping population for these two traits. Ten thousand individuals from a B73 × Mo17 noninbred population intermated for 14 generations (IBM Syn14) were grown at a density of approximately 16,500 plants ha−1. Flowering time and plant height were measured within this population. DNA was pooled from the 46 most extreme individuals from each distributional tail for each of the traits measured and used in bulk segregant analysis (BSA) sequencing. Allelic divergence at each of the ∼1.1 million SNP loci was estimated as the difference in allele frequencies between the selected extremes. Additionally, 224 intermated B73 × Mo17 recombinant inbred lines were concomitantly grown at a similar density adjacent to the large synthetic population and were assessed for flowering time and plant height. Using the BSA sequencing method, 14 and 13 genomic regions were identified for flowering time and plant height, respectively. Linkage mapping with the RIL population identified eight and three regions for flowering time and plant height, respectively. Of the regions identified, three colocalized between the two populations for flowering time and two colocalized for plant height. This study demonstrates the utility of using BSA sequencing for the dissection of complex quantitative traits important for production of lignocellulosic ethanol. PMID:26038364

  11. Whole genome analysis of an MDR Beijing/W strain of Mycobacterium tuberculosis with large genomic deletions associated with resistance to isoniazid.

    PubMed

    Zhang, Qiufen; Wan, Baoshan; Zhou, Aiping; Ni, Jinjing; Xu, Zhihong; Li, Shuxian; Tao, Jing; Yao, YuFeng

    2016-05-15

    Mycobacterium tuberculosis (M.tb) is one of the most prevalent bacterial pathogens in the world. With geographical wide spread and hypervirulence, Beijing/W family is the most successful M.tb lineage. China is a country of high tuberculosis (TB) and high multiple drug-resistant TB (MDR-TB) burden, and the Beijing/W family strains take the largest share of MDR strains. To study the genetic basis of Beijing/W family strains' virulence and drug resistance, we performed the whole genome sequencing of M.tb strain W146, a clinical Beijing/W genotype MDR isolated from Wuxi, Jiangsu province, China. Compared with genome sequence of M.tb strain H37Rv, we found that strain W146 lacks three large fragments and the missing of furA-katG operon confers isoniazid resistance. Besides the missing of furA-katG operon, strain W146 harbored almost all known drug resistance-associated mutations. Comparison analysis of single nucleotide polymorphisms (SNPs) and indels between strain W146 and Beijing/W genotype strains and non-Beijing/W genotype strains revealed that strain W146 possessed some unique mutations, which may be related to drug resistance, transmission and pathogenicity. These findings will help to understand the large sequence polymorphisms (LSPs) and the transmission and drug resistance related genetic characteristics of the Beijing/W genotype of M.tb. PMID:26854371

  12. A corotational flat triangular element for large strain analysis of thin shells with application to soft biological tissues

    NASA Astrophysics Data System (ADS)

    Caselli, Federica; Bisegna, Paolo

    2014-09-01

    A flat triangular element for the nonlinear analysis of thin shells is presented. The formulation relies on (i) a polar decomposition based corotational framework and (ii) a core-element kinematic description adopting the multiplicative superposition of membrane and bending actions. The resulting element is a refined yet simple three-node displacement-based triangle accounting for thickness extensibility and initial shell curvature, and equipped with a fully consistent tangent stiffness. Numerical tests involving shell structures made of rubber-like materials or fibred biological tissues show the effectiveness of the proposed element and its suitability to problems characterized by large displacements, large rotations, large membrane strains and bending. A Matlab toolkit implementing the present formulation is provided as supplementary material.

  13. New Class of Plastic Bulk Metallic Glass

    SciTech Connect

    Chen, L. Y.; Jiang, Q. K.; Wang, X. D.; Cao, Q. P.; Zeng, Y. W.; Jiang, J. Z.; Fu, Z. D.; Zhang, S. L.; Zhang, G. Q.; Hao, X. P.; Wang, B. Y.; Franz, H.; Liu, Y. G.; Xie, H. S.

    2008-02-22

    An intrinsic plastic Cu{sub 45}Zr{sub 46}Al{sub 7}Ti{sub 2} bulk metallic glass (BMG) with high strength and superior compressive plastic strain of up to 32.5% was successfully fabricated by copper mold casting. The superior compressive plastic strain was attributed to a large amount of randomly distributed free volume induced by Ti minor alloying, which results in extensive shear band formation, branching, interaction and self-healing of minor cracks. The mechanism of plasticity presented here suggests that the creation of a large amount of free volume in BMGs by minor alloying or other methods might be a promising new way to enhance the plasticity of BMGs.

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

    SciTech Connect

    Hsieh, B.J.

    1980-04-01

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

  15. Evolution of internal variables in an expanding hollow cylinder at large plastic strains.

    PubMed

    Alexandrov, Sergei; Dinh Kien, Nguyen; Erisov, Yaroslav; Grechnikov, Fedor

    2016-01-01

    An efficient method for calculating the evolution of internal variables in an expanding hollow cylinder of rigid/plastic material is proposed. The conventional constitutive equations for rigid plastic, hardening material are supplemented with quite an arbitrary set of evolution laws for internal variables assuming that the material is incompressible. No restriction is imposed on the hardening law. The problem is solved in Lagrangian coordinates. This significantly facilitates a numerical treatment of the problem. In particular, the initial/boundary value problem is reduced to a system of equations in characteristic coordinates. A finite difference scheme is used for solving these equations. An illustrative example is presented assuming that the internal variables are the equivalent plastic strain and a damage parameter. PMID:27066385

  16. Nonlinear equations for dynamics of pretwisted beams undergoing small strains and large rotations

    NASA Technical Reports Server (NTRS)

    Hodges, D. H.

    1985-01-01

    Nonlinear beam kinematics are developed and applied to the dynamic analysis of a pretwisted, rotating beam element. The common practice of assuming moderate rotations caused by structural deformation in geometric nonlinear analyses of rotating beams was abandoned in the present analysis. The kinematic relations that described the orientation of the cross section during deformation are simplified by systematically ignoring the extensional strain compared to unity in those relations. Open cross section effects such as warping rigidity and dynamics are ignored, but other influences of warp are retained. The beam cross section is not allowed to deform in its own plane. Various means of implementation are discussed, including a finite element formulation. Numerical results obtained for nonlinear static problems show remarkable agreement with experiment.

  17. Large Earthquakes in Low-Strain Regions of Central Asia, Mongolia, and Iran

    NASA Astrophysics Data System (ADS)

    Landgraf, A.

    2014-12-01

    Although often characterized by an apparent low level of seismicity, areas of low-strain accumulation are subjected to considerable seismic and associated natural hazards. However, we are often unaware of these hazards, because in contrast to active plate boundaries, recurrence intervals of ground-rupturing earthquakes are typically on the order of thousands of years. Geodetic or seismicity records may thus not yet reflect full seismic cycles. Low-strain regions may occur in stable continental interiors or tectonically active intracontinental mountain belts, which often comprise areas of spatially disparate reverse and strike-slip faulting, up to thousands of kilometers away from plate boundaries. These regions may be shortened at rates on the order of centimeters per year, with no clear spatiotemporal pattern of seismicity, and single fault-slip rates may attain less than one to a few millimeters per year. The Kyrgyz and Kazakh Tien Shan, the Mongolian Hangay or the Iranian Alborz mountains are prime examples that share these characteristics. These regions are located along the northern rim of the ongoing Indian-Eurasian or Arabian-Eurasian collision, but are hundreds of kilometers away from the corresponding plate boundaries. Historical earthquakes M > 7 are known from the Alborz mountains and several events with M > 8 are known from the northern Tien Shan and Mongolia - all with poorly constrained recurrence rates. We review our ongoing tectonic studies of these areas, which differ in faulting mechanisms, the preservation potential of primary and secondary rupture evidence, and the level of population density and value concentrations. We use paleoseismic trenching, geomorphic and terrestrial LiDAR data analysis, and geochronology to gain insights into the complex deformation processes that govern these areas to better understand how present-day deformation is accommodated in areally extensive deformation zones in continental interiors.

  18. Fracture Toughness Properties of Gd123 Superconducting Bulks

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Murakami, A.

    Fracture toughness properties of melt growth GdBa2Cu3Ox (Gd123) large single domain superconducting bulks with Ag2O of 10 wt% and Pt of 0.5 wt%; 45 mm in diameter and 25 mm in thickness with low void density were evaluated at 77 K through flexural tests of specimens cut from the bulks, and compared to those of a conventional Gd123 with voids. The densified Gd123 bulks were prepared with a seeding and temperature gradient method; first melt processed in oxygen, then crystal growth in air; two-step regulated atmosphere heat treatment. The plane strain fracture toughness, KIC was obtained by the three point flexure test of the specimens with through precrack, referring to the single edge pre-cracked beam (SEPB) method, according to the JIS-R-1607, Testing Methods for Fracture Toughness of High Performance Ceramics. The results show that the fracture toughness of the densified Gd123 bulk with low void density was higher than that of the standard Gd123 bulk with voids, as well as the flexural strength previously reported. We also compared the fracture toughness of as-grown bulks with that of annealed bulks. The relation between the microstructure and the fracture toughness of the Gd123 bulk was clearly shown.

  19. Determination of the shear buckling load of a large polymer composite I-section using strain and displacement sensors.

    PubMed

    Park, Jin Y; Lee, Jeong Wan

    2012-01-01

    This paper presents a method and procedure of sensing and determining critical shear buckling load and corresponding deformations of a comparably large composite I-section using strain rosettes and displacement sensors. The tested specimen was a pultruded composite beam made of vinyl ester resin, E-glass and carbon fibers. Various coupon tests were performed before the shear buckling test to obtain fundamental material properties of the I-section. In order to sensitively detect shear buckling of the tested I-section, twenty strain rosettes and eight displacement sensors were applied and attached on the web and flange surfaces. An asymmetric four-point bending loading scheme was utilized for the test. The loading scheme resulted a high shear and almost zero moment condition at the center of the web panel. The web shear buckling load was determined after analyzing the obtained test data from strain rosettes and displacement sensors. Finite element analysis was also performed to verify the experimental results and to support the discussed experimental approach. PMID:23443364

  20. Compaction process in sedimentary basins: the role of stiffness increase and hardening induced by large plastic strains

    NASA Astrophysics Data System (ADS)

    Deudé, V.; Dormieux, L.; Maghous, S.; Barthélémy, J. F.; Bernaud, D.

    2004-11-01

    This paper is devoted to the simulation of large strain compaction process in sedimentary basins. Special attention is paid to the effects of large porosity changes on the elastic and plastic mechanical properties of the sediment material. The latter are introduced in the constitutive behaviour in the framework of a micromechanical reasoning. In particular, the proposed approach avoids the problem of negative porosities that are predicted by classical models under high confining pressures.Some closed-form solutions are presented in the simplified case of one-dimensional compaction. While the influence of stiffness increase is shown to be negligible as regards the compaction law, it proves to affect significantly the stress and porosity profiles. Copyright

  1. Strain of Synechocystis PCC 6803 with Aberrant Assembly of Photosystem II Contains Tandem Duplication of a Large Chromosomal Region

    PubMed Central

    Tichý, Martin; Bečková, Martina; Kopečná, Jana; Noda, Judith; Sobotka, Roman; Komenda, Josef

    2016-01-01

    Cyanobacterium Synechocystis PCC 6803 represents a favored model organism for photosynthetic studies. Its easy transformability allowed construction of a vast number of Synechocystis mutants including many photosynthetically incompetent ones. However, it became clear that there is already a spectrum of Synechocystis “wild-type” substrains with apparently different phenotypes. Here, we analyzed organization of photosynthetic membrane complexes in a standard motile Pasteur collection strain termed PCC and two non-motile glucose-tolerant substrains (named here GT-P and GT-W) previously used as genetic backgrounds for construction of many photosynthetic site directed mutants. Although, both the GT-P and GT-W strains were derived from the same strain constructed and described by Williams in 1988, only GT-P was similar in pigmentation and in the compositions of Photosystem II (PSII) and Photosystem I (PSI) complexes to PCC. In contrast, GT-W contained much more carotenoids but significantly less chlorophyll (Chl), which was reflected by lower level of dimeric PSII and especially trimeric PSI. We found that GT-W was deficient in Chl biosynthesis and contained unusually high level of unassembled D1-D2 reaction center, CP47 and especially CP43. Another specific feature of GT-W was a several fold increase in the level of the Ycf39-Hlip complex previously postulated to participate in the recycling of Chl molecules. Genome re-sequencing revealed that the phenotype of GT-W is related to the tandem duplication of a large region of the chromosome that contains 100 genes including ones encoding D1, Psb28, and other PSII-related proteins as well as Mg-protoporphyrin methylester cyclase (Cycl). Interestingly, the duplication was completely eliminated after keeping GT-W cells on agar plates under photoautotrophic conditions for several months. The GT-W strain without a duplication showed no obvious defects in PSII assembly and resembled the GT-P substrain. Although, we do not

  2. Strain of Synechocystis PCC 6803 with Aberrant Assembly of Photosystem II Contains Tandem Duplication of a Large Chromosomal Region.

    PubMed

    Tichý, Martin; Bečková, Martina; Kopečná, Jana; Noda, Judith; Sobotka, Roman; Komenda, Josef

    2016-01-01

    Cyanobacterium Synechocystis PCC 6803 represents a favored model organism for photosynthetic studies. Its easy transformability allowed construction of a vast number of Synechocystis mutants including many photosynthetically incompetent ones. However, it became clear that there is already a spectrum of Synechocystis "wild-type" substrains with apparently different phenotypes. Here, we analyzed organization of photosynthetic membrane complexes in a standard motile Pasteur collection strain termed PCC and two non-motile glucose-tolerant substrains (named here GT-P and GT-W) previously used as genetic backgrounds for construction of many photosynthetic site directed mutants. Although, both the GT-P and GT-W strains were derived from the same strain constructed and described by Williams in 1988, only GT-P was similar in pigmentation and in the compositions of Photosystem II (PSII) and Photosystem I (PSI) complexes to PCC. In contrast, GT-W contained much more carotenoids but significantly less chlorophyll (Chl), which was reflected by lower level of dimeric PSII and especially trimeric PSI. We found that GT-W was deficient in Chl biosynthesis and contained unusually high level of unassembled D1-D2 reaction center, CP47 and especially CP43. Another specific feature of GT-W was a several fold increase in the level of the Ycf39-Hlip complex previously postulated to participate in the recycling of Chl molecules. Genome re-sequencing revealed that the phenotype of GT-W is related to the tandem duplication of a large region of the chromosome that contains 100 genes including ones encoding D1, Psb28, and other PSII-related proteins as well as Mg-protoporphyrin methylester cyclase (Cycl). Interestingly, the duplication was completely eliminated after keeping GT-W cells on agar plates under photoautotrophic conditions for several months. The GT-W strain without a duplication showed no obvious defects in PSII assembly and resembled the GT-P substrain. Although, we do not exactly

  3. Bulk nanostructured alloys prepared by flux melting and melt solidification

    SciTech Connect

    Shen, T.D.; Schwarz, R.B.; Zhang, X.

    2005-10-03

    We have prepared bulk nanostructured Ag{sub 60}Cu{sub 40} alloys by a flux-melting and melt-solidification technique. The flux purifies the melts, leading to a large undercooling and nanometer-sized microstructure. The as-prepared alloys are composed of nanolayered Ag and Cu within micrometer-sized grains. The bulk nanostructured alloys have an ultimate tensile strength of approximately 560 MPa, similar yield strength in tension and compression, elongation of 7% in tension, strain hardening exponent of 0.1, and relatively high mechanical and thermal stability up to 400 deg. C.

  4. Large electric-field control of perpendicular magnetic anisotropy in strained [Co/Ni] / PZT heterostructures

    NASA Astrophysics Data System (ADS)

    Gopman, Daniel; Dennis, Cindi; Chen, P. J.; Iunin, Yury; Shull, Robert

    We present a piezoelectric/ferromagnetic heterostructure with PMA - a Co/Ni multilayer sputtered directly onto a Pb(Zr,Ti)O3 (PZT) substrate. Chemical-mechanical polishing was used to reduce the roughness of PZT plates to below 2 nm rms, enabling optimal magnetoelectric coupling via the direct interface between PZT and sputtered Co/Ni films with large PMA (Keff = (95 +/-9 kJ/m3)) . We grew the following layer stack: Ta(3)/Pt(2)/[Co(0.15)/Ni(0.6)]x4/Co(0.15)/Pt(2)/Ta(3); numbers in parentheses indicate thicknesses in nm. Applied electric fields up to +/- 2 MV/m to the PZT generated 0.05% in-plane compression in the Co/Ni multilayer, enabling a large electric-field reduction of the PMA (ΔKeff >= 103 J/m3) and of the coercive field (35%). Our results demonstrate that: (i) heterostructures combining PZT and [Co/Ni] exhibit larger PMA (Keff ~105 J/m3) than previous magnetoelectric heterostructures based on Co/Pt and CoFeB, enabling thermally stable hybrid magnetoelectric/spintronic devices only tens of nm in diameter and (ii) electric-field control of the PMA is promising for more energy efficient switching of spintronic devices.

  5. Large Diameter Femoral Heads Impose Significant Alterations on the Strains Developed on Femoral Component and Bone: A Finite Element Analysis

    PubMed Central

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

    2011-01-01

    Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost’s law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used. PMID:21792381

  6. Micromechanical modelling of short-term and long-term large-strain behaviour of polyethylene terephthalate

    NASA Astrophysics Data System (ADS)

    Poluektov, M.; van Dommelen, J. A. W.; Govaert, L. E.; Yakimets, I.; Geers, M. G. D.

    2013-12-01

    A micromechanically based model is used to describe the mechanical behaviour of polyethylene terephthalate (PET) under uniaxial compression up to large strains and at different temperatures. The creep behaviour of isotropic PET is simulated and compared to experimental data to demonstrate the applicability of the model to describe the long-term response. The material is modelled as an aggregate of two-phase layered domains, where different constitutive laws are used for the phases. A hybrid interaction law between the domains is adopted. The crystalline phase is modelled with crystal plasticity and the amorphous phase with the Eindhoven Glassy Polymer model, taking into account material ageing effects. Model parameters for the selected constitutive laws of the phases are identified from uniaxial compression tests for fully amorphous material and semicrystalline material. Texture evolution during the deformation predicted by the model adequately matches previously observed texture evolution.

  7. Absence of SpeB production in virulent large capsular forms of group A streptococcal strain 64.

    PubMed

    Raeder, R; Harokopakis, E; Hollingshead, S; Boyle, M D

    2000-02-01

    Passage in human blood of group A streptococcal isolate 64p was previously shown to result in the enhanced expression of M and M-related proteins. Similarly, when this isolate was injected into mice via an air sac model for skin infection, organisms recovered from the spleens showed both increased expression of M and M-related proteins and increased skin-invasive potential. We show that these phenotypic changes were not solely the result of increased transcription of the mRNAs encoding the M and M-related gene products. Rather, the altered expression was associated with posttranslational modifications of the M and M-related proteins that occur in this strain, based on the presence or absence of another virulence protein, the streptococcal cysteine protease SpeB. The phenotypic variability also correlates with colony size variation. Large colonies selected by both regimens expressed more hyaluronic acid, which may explain differences in colony morphology. All large-colony variants were SpeB negative and expressed three distinct immunoglobulin G (IgG)-binding proteins in the M and M-related protein family. Small-colony variants were SpeB positive and bound little IgG through their M and M-related proteins because these proteins, although made, were degraded or altered in profile by the SpeB protease. We conclude that passage in either human blood or a mouse selects for a stable, phase-varied strain of group A streptococci which is altered in many virulence properties. PMID:10639442

  8. Absence of SpeB Production in Virulent Large Capsular Forms of Group A Streptococcal Strain 64

    PubMed Central

    Raeder, Roberta; Harokopakis, Evlambia; Hollingshead, Susan; Boyle, Michael D. P.

    2000-01-01

    Passage in human blood of group A streptococcal isolate 64p was previously shown to result in the enhanced expression of M and M-related proteins. Similarly, when this isolate was injected into mice via an air sac model for skin infection, organisms recovered from the spleens showed both increased expression of M and M-related proteins and increased skin-invasive potential. We show that these phenotypic changes were not solely the result of increased transcription of the mRNAs encoding the M and M-related gene products. Rather, the altered expression was associated with posttranslational modifications of the M and M-related proteins that occur in this strain, based on the presence or absence of another virulence protein, the streptococcal cysteine protease SpeB. The phenotypic variability also correlates with colony size variation. Large colonies selected by both regimens expressed more hyaluronic acid, which may explain differences in colony morphology. All large-colony variants were SpeB negative and expressed three distinct immunoglobulin G (IgG)-binding proteins in the M and M-related protein family. Small-colony variants were SpeB positive and bound little IgG through their M and M-related proteins because these proteins, although made, were degraded or altered in profile by the SpeB protease. We conclude that passage in either human blood or a mouse selects for a stable, phase-varied strain of group A streptococci which is altered in many virulence properties. PMID:10639442

  9. Rheology and microstructure of non-Brownian suspensions in the liquid and crystal coexistence region: strain stiffening in large amplitude oscillatory shear.

    PubMed

    Lee, Young Ki; Nam, Jaewook; Hyun, Kyu; Ahn, Kyung Hyun; Lee, Seung Jong

    2015-05-28

    Concentrated hard-sphere suspensions in the liquid and crystal coexistence region show a unique nonlinear behavior under a large amplitude oscillatory shear flow, the so-called strain stiffening, in which the viscosity or modulus suddenly starts to increase near a critical strain amplitude. Even though this phenomenon has been widely reported in experiments, its key mechanism has never been investigated in a systematic way. To have a good understanding of this behavior, a numerical simulation was performed using the lattice Boltzmann method (LBM). Strain stiffening was clearly observed at large strain amplitudes, and the critical strain amplitude showed an angular frequency dependency. The distortion of the shear stress appeared near the critical strain amplitude, and the nonlinear behavior was quantified by the Fourier transformation (FT) and the stress decomposition methods. Above the critical strain amplitude, an increase in the global bond order parameter Ψ(6) was observed at the flow reversal. The maximum of Ψ(6) and the maximum shear stress occurred at the same strain. These results show how strongly the ordered structure of the particles is related to the stress distortion. The ordered particles maintained a bond number of "two" with alignment with the compressive axis, and they were distributed over a narrow range of angular distribution (110°-130°). In addition, the ordered structure was formed near the lowest shear rate region (the flow reversal). The characteristics of the ordered structure were remarkably different from those of the hydroclusters which are regarded as the origin of shear thickening. It is clear that strain stiffening and shear thickening originate from different mechanisms. Our results clearly demonstrate how the ordering of the particles induces strain stiffening in the liquid and crystal coexistence region. PMID:25909879

  10. Strain-driven band inversion and topological aspects in Antimonene

    PubMed Central

    Zhao, Mingwen; Zhang, Xiaoming; Li, Linyang

    2015-01-01

    Searching for the two-dimensional (2D) topological insulators (TIs) with large bulk band gaps is the key to achieve room-temperature quantum spin Hall effect (QSHE). Using first-principles calculations, we demonstrated that the recently-proposed antimonene [Zhang et al., Angew. Chem. Int. Ed. 54, 3112–3115 (2015)] can be tuned to a 2D TI by reducing the buckling height of the lattice which can be realized under tensile strain. The strain-driven band inversion in the vicinity of the Fermi level is responsible for the quantum phase transition. The buckled configuration of antimonene enables it to endure large tensile strain up to 18% and the resulted bulk band gap can be as large as 270 meV. The tunable bulk band gap makes antimonene a promising candidate material for achieving quantum spin Hall effect (QSH) at high temperatures which meets the requirement of future electronic devices with low power consumption. PMID:26537994

  11. Bulk Email Forensics

    NASA Astrophysics Data System (ADS)

    Cohen, Fred

    Legal matters related to unsolicited commercial email often involve several hundred thousand messages. Manual examination and interpretation methods are unable to deal with such large volumes of evidence. Furthermore, as the actors gain experience, it is increasingly difficult to show evidence of spoliation and detect intentional evidence construction. This paper presents improved automated techniques for bulk email analysis and presentation to aid in evidence interpretation.

  12. [INVITED] Ultrafast laser photoinscription of large-mode-area waveguiding structures in bulk dielectrics. Invited paper for the section : Hot topics in Ultrafast Lasers

    NASA Astrophysics Data System (ADS)

    Stoian, R.; D'Amico, C.; Bhuyan, M. K.; Cheng, G.

    2016-06-01

    Ultrafast laser photoinscription and laser-based refractive index engineering develop towards a unique way for three-dimensional optical design inside bulk materials for the conception of embedded photonic applications. The specific optical functions for the light guiding elements, notably their single mode characteristics and the accessible spectral domains, depend on the achieved refractive index contrast in the material transparency window and on the characteristic dimensions of the optical modification. We give here an overview of several laser processing options, developed to increase the effective index area and contrast using pulse engineering methods in space and time, and optical design involving focal shaping, tubular concepts, evanescently coupled waveguide arrays, or structured waveguides.

  13. Predeformation and Subsequent Annealing—A Way for Controlling Morphology of Carbides in Large Dimensional Bulk Nanocrystalline Fe-Al-Cr Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Hongding; La, Peiqing; Shi, Ting; Wei, Yupeng; Jiao, Huisheng

    2014-01-01

    In this study, a processing route is introduced to control the morphology of carbide and the grain size of nanocrystalline matrix of Fe-Al-Cr alloy. After predeformation followed by annealing treatment, the grain size of nanocrystalline matrix decreased slightly and the Cr7C3 phases transformed from a fiber shape to the globular shape. The yield strength and the flow stress of the alloy increased from 1048 to 1338 MPa and 1150 to 1550 MPa, respectively, while the ductility of the alloy also became better. This proposed method may open a way for controlling the morphology of carbide and the grain size of matrix in bulk nanocrystalline materials to receive higher strength and better plasticity.

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

    DOEpatents

    Reed, Evan J.; Armstrong, Michael R.

    2010-09-07

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

  15. Extraordinarily large perpendicular magnetic anisotropy in epitaxially strained cobalt-ferrite Co{sub x}Fe{sub 3−x}O{sub 4}(001) (x = 0.75, 1.0) thin films

    SciTech Connect

    Niizeki, Tomohiko; Utsumi, Yuji; Aoyama, Ryohei; Yanagihara, Hideto; Inoue, Jun-ichiro; Kita, Eiji; Yamasaki, Yuichi; Nakao, Hironori; Koike, Kazuyuki

    2013-10-14

    Perpendicular magnetic anisotropy (PMA) of cobalt-ferrite Co{sub x}Fe{sub 3-x}O{sub 4} (x = 0.75 and 1.0) epitaxial thin films grown on MgO (001) by a reactive magnetron sputtering technique was investigated. The saturation magnetization was found to be 430 emu/cm{sup 3} for x = 0.75, which is comparable to that of bulk CoFe{sub 2}O{sub 4} (425 emu/cm{sup 3}). Torque measurements afforded PMA constants of K{sub u}{sup eff}=9.0 Merg/cm{sup 3} (K{sub u}=10.0 Merg/cm{sup 3}) and K{sub u}{sup eff}=9.7 Merg/cm{sup 3} for x = 0.75 and 1.0, respectively. The value of K{sub u}{sup eff} extrapolated using Miyajima's plot was as high as 14.7 Merg/cm{sup 3} for x = 1.0. The in-plane four-fold magnetic anisotropy was evaluated to be 1.6 Merg/cm{sup 3} for x = 0.75. X-ray diffraction measurement revealed our films to be pseudomorphically strained on MgO (001) with a Poisson ratio of 0.4, leading to a considerable in-plane tensile strain by which the extraordinarily large PMA could be accounted for.

  16. Effects of airplane flexibility on wing strains in rough air at 35,000 feet as determined by a flight investigation of a large swept-wing airplane

    NASA Technical Reports Server (NTRS)

    Rhyne, Richard H

    1958-01-01

    A flight investigation was made on a large sweptback-wing bomber airplane and the results are compared with data previously obtained at low altitude (5,000 feet). The effects of wing flexibility on the wing strains were, on the average, about 20 percent larger at the higher altitude.

  17. Subunit Q Is Required to Stabilize the Large Complex of NADPH Dehydrogenase in Synechocystis sp. Strain PCC 6803.

    PubMed

    Zhao, Jiaohong; Rong, Weiqiong; Gao, Fudan; Ogawa, Teruo; Ma, Weimin

    2015-06-01

    Two major complexes of NADPH dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1, NdhF1, and NdhP, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, NDH-1-dependent cyclic electron transport around photosystem I, and CO2 uptake. Two mutants sensitive to high light for growth and impaired in cyclic electron transport around photosystem I were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in an open reading frame encoding a product highly homologous to NdhQ, a single-transmembrane small subunit of the NDH-1L complex, identified in Thermosynechococcus elongatus by proteomics strategy. Deletion of ndhQ disassembled about one-half of the NDH-1L to NDH-1M and consequently impaired respiration, but not CO2 uptake. During prolonged incubation of the thylakoid membrane with n-dodecyl-β-D-maltoside at room temperature, the rest of the NDH-1L in ΔndhQ was disassembled completely to NDH-1M and was much faster than in the wild type. In the ndhP-deletion mutant (ΔndhP) background, absence of NdhQ almost completely disassembled the NDH-1L to NDH-1M, similar to the results observed in the ΔndhD1/ΔndhD2 mutant. We therefore conclude that both NdhQ and NdhP are essential to stabilize the NDH-1L complex. PMID:25873552

  18. Comparison of the large-scale periplasmic proteomes of the Escherichia coli K-12 and B strains.

    PubMed

    Han, Mee-Jung; Kim, Jin Young; Kim, Jung A

    2014-04-01

    Escherichia coli typically secretes many proteins into the periplasmic space, and the periplasmic proteins have been used for the secretory production of various proteins by the biotechnology industry. However, the identity of all of the E. coli periplasmic proteins remains unknown. Here, high-resolution periplasmic proteome reference maps of the E. coli K-12 and B strains were constructed and compared. Of the 145 proteins identified by tandem mass spectrometry, 61 proteins were conserved in the two strains, whereas 11 and 12 strain-specific proteins were identified for the E. coli K-12 and B strains, respectively. In addition, 27 proteins exhibited differences in intensities greater than 2-fold between the K-12 and B strains. The periplasmic proteins MalE and OppA were the most abundant proteins in the two E. coli strains. Distinctive differences between the two strains included several proteins that were caused by genetic variations, such as CybC, FliC, FliY, KpsD, MglB, ModA, and Ybl119, hydrolytic enzymes, particularly phosphatases, glycosylases, and proteases, and many uncharacterized proteins. Compared to previous studies, the localization of many proteins, including 30 proteins for the K-12 strain and 53 proteins for the B strain, was newly identified as periplasmic. This study identifies the largest number of proteins in the E. coli periplasm as well as the dynamics of these proteins. Additionally, these findings are summarized as reference proteome maps that will be useful for studying protein secretion and may provide new strategies for the enhanced secretory production of recombinant proteins. PMID:24140104

  19. Experimental and theoretical analyses of the age-dependent large-strain behavior of Sylgard 184 (10:1) silicone elastomer.

    PubMed

    Hopf, R; Bernardi, L; Menze, J; Zündel, M; Mazza, E; Ehret, A E

    2016-07-01

    The commercial polydimethysiloxane elastomer Sylgard(®) 184 with mixing ratio 10:1 is in wide use for biomedical research or fundamental studies of mechanobiology. In this paper, a comprehensive study of the large strain mechanical behavior of this material under multiaxial monotonic and cyclic loads, and its change during the first 26 days after preparation is reported. The equibiaxial stress response studied in inflation experiments reveals a much stiffer and more nonlinear response compared to the uniaxial and pure shear characteristics. The polymer revealed remarkably elastic behavior, in particular, very little dependence on strain rates between 0.3%/s and 11%/s, and on the strain history in cyclic experiments. On the other hand, both the small-strain and large strain nonlinear mechanical characteristics of the elastomer are changing with sample age and the results suggest that this process has not ceased after 26 days. A recent re-interpretation of the well-known Ogden model for incompressible rubber-like materials was applied to rationalize the results and accurate agreement was obtained with the experimental data over all testing configurations and testing times. The change of a single parameter in this model is shown to govern the evolution of the nonlinear material characteristics with sample age, attributed to a continuation of the cross-linking process. Based on a kinetic relation to account for this process over time, the model provided successful predictions of the material behavior even after more than one year. PMID:26990071

  20. Flow Curve Determination at Large Plastic Strain Levels: Limitations of the Membrane Theory in the Analysis of the Hydraulic Bulge Test

    NASA Astrophysics Data System (ADS)

    Lemoine, X.; Iancu, A.; Ferron, G.

    2011-05-01

    Nowadays, an accurate determination of the true stress-strain curve is a key-element for all finite element (FE) forming predictions. Since the introduction of Advanced High Strength Steels (AHSS) for the automotive market, the standard uniaxial tension test suffers the drawback of relatively low uniform elongations. The extrapolation of the uniaxial stress-strain curve up to large strains is not without consequence in forming predictions—especially formability and springback. One of the means to solve this problem is to use experimental tests where large plastic strain levels can be reached. The hydraulic bulge test is one of these tests. The effective plastic strain levels reached in the bulge test are of about 0.7. From an experimental standpoint, the biaxial flow stress is estimated using measurement of fluid pressure, and calculation of thickness and curvature at the pole, via appropriate measurements and assumptions. The biaxial stress at the pole is determined using the membrane equilibrium equation. The analysis proposed in this paper consists of performing "virtual experiments" where the results obtained by means of FE calculations are used as input data for determining the biaxial stress-strain law in agreement with the experimental procedure. In this way, a critical discussion of the experimental procedure can be made, by comparing the "experimental" stress-strain curve (Membrane theory curve) with the "reference" one introduced in the simulations. In particular, the influences of the "(die diameter)/thickness" ratio and of the plastic anisotropy are studied, and limitations of the hydraulic bulge test analysis are discussed.

  1. Bulk pesticide storage - state perspective

    SciTech Connect

    Buzicky, G.

    1994-12-31

    State bulk pesticide storage regulations continue to evolve differentially due, in large part, to the absence of federal regulations. This is about to change because of the pending promulgation of 40 CFR Part 165, as amended in 1988 by the Environmental Protection Agency (EPA) rules regarding storage, handling and disposal. Until final adoption of the rules by EPA, states continue to address bulk pesticide storage and handling according to individual state statute, rules and guidelines.

  2. Unique Piezoelectric Properties of the Monoclinic Phase in Pb (Zr ,Ti )O3 Ceramics: Large Lattice Strain and Negligible Domain Switching

    NASA Astrophysics Data System (ADS)

    Fan, Longlong; Chen, Jun; Ren, Yang; Pan, Zhao; Zhang, Linxing; Xing, Xianran

    2016-01-01

    The origin of the excellent piezoelectric properties at the morphotropic phase boundary is generally attributed to the existence of a monoclinic phase in various piezoelectric systems. However, there exist no experimental studies that reveal the role of the monoclinic phase in the piezoelectric behavior in phase-pure ceramics. In this work, a single monoclinic phase has been identified in Pb (Zr ,Ti )O3 ceramics at room temperature by in situ high-energy synchrotron x-ray diffraction, and its response to electric field has been characterized for the first time. Unique piezoelectric properties of the monoclinic phase in terms of large intrinsic lattice strain and negligible domain switching have been observed. The extensional strain constant d33 and the transverse strain constant d31 are calculated to be 520 and -200 pm /V , respectively. These large piezoelectric coefficients are mainly due to the large intrinsic lattice strain, with very little extrinsic contribution from domain switching. The unique properties of the monoclinic phase provide new insights into the mechanisms responsible for the piezoelectric properties at the morphotropic phase boundary.

  3. A UNIFIED MONTE CARLO TREATMENT OF GAS-GRAIN CHEMISTRY FOR LARGE REACTION NETWORKS. II. A MULTIPHASE GAS-SURFACE-LAYERED BULK MODEL

    SciTech Connect

    Vasyunin, A. I.; Herbst, Eric E-mail: eh2ef@virginia.edu

    2013-01-10

    The observed gas-phase molecular inventory of hot cores is believed to be significantly impacted by the products of chemistry in interstellar ices. In this study, we report the construction of a full macroscopic Monte Carlo model of both the gas-phase chemistry and the chemistry occurring in the icy mantles of interstellar grains. Our model treats icy grain mantles in a layer-by-layer manner, which incorporates laboratory data on ice desorption correctly. The ice treatment includes a distinction between a reactive ice surface and an inert bulk. The treatment also distinguishes between zeroth- and first-order desorption, and includes the entrapment of volatile species in more refractory ice mantles. We apply the model to the investigation of the chemistry in hot cores, in which a thick ice mantle built up during the previous cold phase of protostellar evolution undergoes surface reactions and is eventually evaporated. For the first time, the impact of a detailed multilayer approach to grain mantle formation on the warm-up chemistry is explored. The use of a multilayer ice structure has a mixed impact on the abundances of organic species formed during the warm-up phase. For example, the abundance of gaseous HCOOCH{sub 3} is lower in the multilayer model than in previous grain models that do not distinguish between layers (so-called two phase models). Other gaseous organic species formed in the warm-up phase are affected slightly. Finally, we find that the entrapment of volatile species in water ice can explain the two-jump behavior of H{sub 2}CO previously found in observations of protostars.

  4. Lagrangian numerical techniques for modelling multicomponent flow in the presence of large viscosity contrasts: Markers-in-bulk versus Markers-in-chain

    NASA Astrophysics Data System (ADS)

    Mulyukova, Elvira; Dabrowski, Marcin; Steinberger, Bernhard

    2015-04-01

    Many problems in geodynamic applications may be described as viscous flow of chemically heterogeneous materials. Examples include subduction of compositionally stratified lithospheric plates, folding of rheologically layered rocks, and thermochemical convection of the Earth's mantle. The associated time scales are significantly shorter than that of chemical diffusion, which justifies the commonly featured phenomena in geodynamic flow models termed contact discontinuities. These are spatially sharp interfaces separating regions of different material properties. Numerical modelling of advection of fields with sharp interfaces is challenging. Typical errors include numerical diffusion, which arises due to the repeated action of numerical interpolation. Mathematically, a material field can be represented by discrete indicator functions, whose values are interpreted as logical statements (e.g. whether or not the location is occupied by a given material). Interpolation of a discrete function boils down to determining where in the intermediate node-positions one material ends, and the other begins. The numerical diffusion error thus manifests itself as an erroneous location of the material-interface. Lagrangian advection-schemes are known to be less prone to numerical diffusion errors, compared to their Eulerian counterparts. The tracer-ratio method, where Lagrangian markers are used to discretize the bulk of materials filling the entire domain, is a popular example of such methods. The Stokes equation in this case is solved on a separate, static grid, and in order to do it - material properties must be interpolated from the markers to the grid. This involves the difficulty related to interpolation of discrete fields. The material distribution, and thus material-properties like viscosity and density, seen by the grid is polluted by the interpolation error, which enters the solution of the momentum equation. Errors due to the uncertainty of interface-location can be

  5. Plasticity in the Supercooled Liquid Region of Bulk Metallic Glasses

    SciTech Connect

    Nieh, T G; Wadsworth, J; Liu, C T; Ice, G E

    2000-10-30

    Intensive efforts have been carried out over the past decade to develop means to slow down the phase transformation kinetics during the forming of metallic glasses. As a result of these efforts, some metallic glasses can now be fabricated in bulk forms (BMG) from the liquid state at cooling rates on the order of 1-10 K/s, which is close to that of conventional casting. This enables the production of bulk amorphous alloys with a thickness of {approx}10 mm. While advances in amorphous metallic alloy development have been impressive, they have been made largely through experience [1]. Three main conclusions drawn from this study are: (1) Bulk metallic glasses generally have excellent mechanical formability in the supercooled liquid region. (2) Bulk metallic glasses may not be necessarily behave like a Newtonian fluid (i.e. m=1). The non-Newtonian behavior is associated with glass instability during deformation. (3) Multi-component Bulk metallic glasses can be used as the precursor of a nanocrystalline solid. However, the nanocrystalline solid is not necessarily superplastic. The non-superplastic behavior is caused by the difficult strain accommodation at grain triple junctions.

  6. The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity.

    PubMed

    Bourbouli, Maria; Katsifas, Efstathios A; Papathanassiou, Evangelos; Karagouni, Amalia D

    2015-05-01

    Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds. PMID:25627249

  7. 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.

  8. Infection of a Single Cell Line with Distinct Strains of Human Cytomegalovirus Can Result in Large Variations in Virion Production and Facilitate Efficient Screening of Virus Protein Function

    PubMed Central

    Zavala, Anamaria G.; O'Dowd, John M.

    2015-01-01

    ABSTRACT Previously, we reported that the absence of the ataxia telangiectasia mutated (ATM) kinase, a critical DNA damage response (DDR) signaling component for double-strand breaks, caused no change in HCMV Towne virion production. Later, others reported decreased AD169 viral titers in the absence of ATM. To address this discrepancy, human foreskin fibroblasts (HFF) and three ATM− lines (GM02530, GM05823, and GM03395) were infected with both Towne and AD169. Two additional ATM− lines (GM02052 and GM03487) were infected with Towne. Remarkably, both previous studies' results were confirmed. However, the increased number of cell lines and infections with both lab-adapted strains confirmed that ATM was not necessary to produce wild-type-level titers in fibroblasts. Instead, interactions between individual virus strains and the cellular microenvironment of the individual ATM− line determined efficiency of virion production. Surprisingly, these two commonly used lab-adapted strains produced drastically different titers in one ATM− cell line, GM05823. The differences in titer suggested a rapid method for identifying genes involved in differential virion production. In silico comparison of the Towne and AD169 genomes determined a list of 28 probable candidates responsible for the difference. Using serial iterations of an experiment involving virion entry and input genome nuclear trafficking with a panel of related strains, we reduced this list to four (UL129, UL145, UL147, and UL148). As a proof of principle, reintroduction of UL148 largely rescued genome trafficking. Therefore, use of a battery of related strains offers an efficient method to narrow lists of candidate genes affecting various virus life cycle checkpoints. IMPORTANCE Human cytomegalovirus (HCMV) infection of multiple cell lines lacking ataxia telangiectasia mutated (ATM) protein produced wild-type levels of infectious virus. Interactions between virus strains and the microenvironment of individual

  9. Flexoelectricity as a bulk property

    NASA Astrophysics Data System (ADS)

    Resta, Raffaele

    2010-03-01

    Piezoelectric composites can be created using nonpiezoelectric materials, by exploiting flexoelectricity. This is by definition the linear response of polarization to strain gradient, and is symmetry-allowed even in elemental crystals. However, the basic issue whether flexoelectricity is a bulk or a surface material property is open. We mention that the analogous issue about piezoelectricity is nontrivial either.^1 In this first attempt towards a full theory of flexoelectricity we prove that, for a simple class of strain and strain gradients, flexoelectricity is indeed a bulk effect. The key ingredients of the present theory are the long-range perturbations linearly induced by a unit displacement of a single nucleus in an otherwise perfect crystal: to leading order these are dipolar, quadrupolar, and octupolar. The corresponding tensors have rank 2, 3, and 4, respectively. Whereas dipoles and quadrupoles provide the piezoelectric response,^1 we show that dipoles and octupoles provide the flexoelectric response in nonpiezoelectric crystals. We conjecture that the full dipole and octupole tensors provide the flexoelectric response to the most general form of strain gradient. Our problem has a close relationship to the one of the ``absolute'' deformation potentials, which is based on a similar kind of dipolar and octupolar tensors.^2 ^1 R. M. Martin, Phys. Rev. B 5, 1607 (1972). ^2 R. Resta, L. Colombo and S. Baroni, Phys. Rev. B 41, 12538 (1990).

  10. Micromechanical poroelastic finite element and shear-lag models of tendon predict large strain dependent Poisson's ratios and fluid expulsion under tensile loading.

    PubMed

    Ahmadzadeh, Hossein; Freedman, Benjamin R; Connizzo, Brianne K; Soslowsky, Louis J; Shenoy, Vivek B

    2015-08-01

    As tendons are loaded, they reduce in volume and exude fluid to the surrounding medium. Experimental studies have shown that tendon stretching results in a Poisson's ratio greater than 0.5, with a maximum value at small strains followed by a nonlinear decay. Here we present a computational model that attributes this macroscopic observation to the microscopic mechanism of the load transfer between fibrils under stretch. We develop a finite element model based on the mechanical role of the interfibrillar-linking elements, such as thin fibrils that bridge the aligned fibrils or macromolecules such as glycosaminoglycans (GAGs) in the interfibrillar sliding and verify it with a theoretical shear-lag model. We showed the existence of a previously unappreciated structure-function mechanism whereby the Poisson's ratio in tendon is affected by the strain applied and interfibrillar-linker properties, and together these features predict tendon volume shrinkage under tensile loading. During loading, the interfibrillar-linkers pulled fibrils toward each other and squeezed the matrix, leading to the Poisson's ratio larger than 0.5 and fluid expulsion. In addition, the rotation of the interfibrillar-linkers with respect to the fibrils at large strains caused a reduction in the volume shrinkage and eventual nonlinear decay in Poisson's ratio at large strains. Our model also predicts a fluid flow that has a radial pattern toward the surrounding medium, with the larger fluid velocities in proportion to the interfibrillar sliding. PMID:25934322

  11. Observation of magnetic-field-induced transformation in MnCo0.78Fe0.22Ge alloys with colossal strain output and large magnetocaloric effect

    NASA Astrophysics Data System (ADS)

    Wang, Zilong; Xiu, Pengyuan; Huang, Lian; Nie, Zhihua; Zeng, Junxi; Brown, Dennis E.; Ren, Yang; Wang, Yandong

    2016-05-01

    The thermal, structural and magnetic properties were studied for the hexagonal MnCo0.78Fe0.22Ge alloys, which undergoes a first-order phase transformation from paramagnetic hexagonal phase into ferromagnetic orthorhombic martensite on cooling. Owing to the magnetostructural coupling, large magnetocaloric effect (∆SM=-10.97 J kg-1 K-1) was obtained at 254 K. In-situ synchrotron high-energy X-ray diffraction experiments were conducted to reveal the detailed change in crystallographic structure of phases and the effect of applied magnetic field on phase transformation behaviors. An anomalously huge strain of 11.89% and volume expansion of 4.35% in unit-cell were obtained between martensite and parent phase across the transformation. Furthermore, the magnetic field-induced martensitic transformation was directly evidenced at 250 K, which eventually demonstrates the possibility to achieve magnetic-field-induced strain and large magnetocaloric effect simultaneously.

  12. Interseismic Strain Accumulation in the Imperial Valley and Implications for Triggering of Large Earthquakes in Southern California

    NASA Astrophysics Data System (ADS)

    Crowell, B. W.; Bock, Y.; Sandwell, D. T.

    2009-12-01

    From February, 2008 to March, 2009, we performed three rapid-static Global Positioning System (GPS) surveys of 115 geodetic monuments stretching from the United States-Mexico border into the Coachella Valley using the method of instantaneous positioning. The monuments are located in key areas near the Imperial, Superstition Hills, San Jacinto, San Andreas and Brawley Faults with nominal baselines generally less than 10 km. We perform a bicubic spline interpolation on the crustal motion vectors from the campaign measurements and 1005 continuous GPS monuments in western North America and solve for the velocity gradient tensor to look at the maximum shear strain, dilatation and rotation rates in the Imperial Valley. We then compare our computed strain field to that computed using the Southern California Earthquake Center Crustal Motion Map 3.0, which extends through 2003 and includes 840 measurements. We show that there is an interseismic strain transient that corresponds to an increase in the maximum shear strain rate of 0.7 μstrain/yr near Obsidian Buttes since 2003 along a fault referred to as the Obsidian Buttes Fault (OBF). A strong subsidence signal of 27 mm/yr and a left-lateral increase of 10 mm/yr are centered along the OBF. Changes in the dilatation and rotation rates confirm the increase in left-lateral motion, as well as infer a strong increase in spreading rate in the southern Salton Sea. The increase in spreading rate has caused an accelerated slip rate along the southern San Andreas near Durmid Hill as evidenced by continuous GPS, which has the potential for earthquake triggering.

  13. Structural features and high quasi-static strain rate sensitivity of Au{sub 49}Cu{sub 26.9}Ag{sub 5.5}Pd{sub 2.3}Si{sub 16.3} bulk metallic glass

    SciTech Connect

    Ketov, S. V.; Chen, N.; Inoue, A.; Louzguine-Luzgin, D. V.; Caron, A.

    2012-12-10

    Here we report on the formation of a crystalline Au-based solid solution surface layer on solidification, which is responsible for yellow color of the Au-based bulk metallic glass (BMG) samples. The structure of the BMG alloy was studied by X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. The deformation behavior of these Au-based BMG samples on heating was studied at temperatures above T{sub g} at different strain rates.

  14. Complete Genome Sequence of the Multiresistant Acinetobacter baumannii Strain AbH12O-A2, Isolated during a Large Outbreak in Spain.

    PubMed

    Merino, M; Alvarez-Fraga, L; Gómez, M J; Aransay, A M; Lavín, J L; Chaves, F; Bou, G; Poza, M

    2014-01-01

    We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated during a large outbreak in Spain. The genome has 3,875,775 bp and 3,526 coding sequences, with 39.4% G+C content. The availability of this genome will facilitate the study of the pathogenicity of the Acinetobacter species. PMID:25395646

  15. Complete Genome Sequence of the Multiresistant Acinetobacter baumannii Strain AbH12O-A2, Isolated during a Large Outbreak in Spain

    PubMed Central

    Merino, M.; Alvarez-Fraga, L.; Gómez, M. J.; Aransay, A. M.; Lavín, J. L.; Chaves, F.

    2014-01-01

    We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated during a large outbreak in Spain. The genome has 3,875,775 bp and 3,526 coding sequences, with 39.4% G+C content. The availability of this genome will facilitate the study of the pathogenicity of the Acinetobacter species. PMID:25395646

  16. The adjuvant activity of a non-toxic, water-soluble glycopeptide present in large quantities in the culture filtrate of Mycobacterium tuberculosis strain DT.

    PubMed Central

    Stewart-Tull, D E; Shimono, T; Kotani, S; Kato, M; Ogawa, Y; Yamamura, Y; Koga, T; Pearson, C M

    1975-01-01

    A water-soluble mycobacterial glycopeptide was obtained in large quantities from the culture supernatant fluid of M. tuberculosis strain DT. This glycopeptide was strongly adjuvant-active when injected, in a water-in-oil emulsion contianing ovalbumin, into guinea-pigs. In addition, it was devoid of cord factor toxicity in mice, polyarthritogenic activity in rats and cavity stimulating activity in rabbit lungs. Images FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 FIG. 8 PMID:806515

  17. Long Pathways for Outgassing Generated by a Rapid and Large Shear Strain of Bubbly Fluids Reducing Effective Viscosity and Affecting Eruption Styles

    NASA Astrophysics Data System (ADS)

    Namiki, A.; Tanaka, Y.

    2015-12-01

    The styles of basaltic explosive eruptions have a wide variety, which is usually attributed to the separation of volcanic gas from the surrounding silicate melt. As a mechanism of gas separation, shear deformation has been suggested. However, the bubble shape evolution under large strain at high strain rate and its effects on viscosity have not yet understood well. We thus performed shear deformation experiments of bubbly liquid under high shear rate and large strain with in situ observation of bubble deformation and viscosity measurements. We used syrup solution as a magma analogue whose viscosity of 3, 50, 500 Pa s, similar to that of basaltic magma. We rotated disc-shaped bubbly syrup at shear rates of 0.03-10 s-1 with strains of 3-1000. Experiments show that deformed bubbles coalesce into larger bubbles and finally generate concentric air rings, resulting that the striped shape of air and liquid parts appears. The widths of air rings greatly exceed the bubble sizes and can be long outgassing pathways if those exist in a volcanic conduit. During the evolution of air rings the measured effective viscosity decreases, while after reaching to a steady state, viscous resistance increases again. At this stage, bubble volume and size in the liquid parts become considerably small. Time evolution of bubble size distribution suggests that most of bubbles are assimilated into the air rings and the remnants in the liquid parts break up into small bubbles. Similar shear deformation of bubbly magma could occur in volcanic conduits, which generates large bubbles at a depth where the lower effective viscosity enhances the ascending velocity. The large bubbles may originate Strombolian eruption or suppresses the explosive eruption by making the long outgassing pathways reaching to the Earth's surface. In both cases, bubble free dense melt accumulates at a shallow conduit. Our experiments suggest that, for larger melt viscosity and narrower conduit, the gas separation occurs

  18. A hierarchically structured graphene foam and its potential as a large-scale strain-gauge sensor.

    PubMed

    Kuang, Jun; Liu, Luqi; Gao, Yun; Zhou, Ding; Chen, Zhuo; Han, Baohang; Zhang, Zhong

    2013-12-21

    A hierarchically structured thermal-reduced graphene (ReG) foam with 0.5 S cm(-1) electrical conductivity is fabricated from a well-dispersed graphene oxide suspension via a directional freezing method followed by high-temperature thermal treatment. The as-prepared three-dimensional ReG foam has an ordered macroporous honeycomb-like structure with straight and parallel voids in the range of 30 μm to 75 μm separated by cell walls of several tens of nanometers thick. Despite its ultra-low density, the ReG foam has an excellent compression recovery along its in-plane direction. This property of the ReG foam can be attributed to its hierarchically porous structure, as demonstrated by the compression test. The excellent compression recovery and high conductivity provide the ReG foam with exceptional piezoresistive capabilities. The electrical resistance of the ReG foam shows a linearly decreasing trend with compressive strain increments of up to 60%, which cannot be observed in conventional rigid material-based sensors and carbon nanotube-based polymer sensors. Such intriguing linear strain-responsive behavior, along with the fast response time and high thermal stability, makes the ReG foam a promising candidate for strain sensing. We demonstrated that it could be used as a wearable device for real-time monitoring of human health. PMID:24142261

  19. Deformation mechanism transition caused by strain rate in a pulse electric brush-plated nanocrystalline Cu

    NASA Astrophysics Data System (ADS)

    Jiang, Zhonghao; Zhang, Hanzhuo; Gu, Changdong; Jiang, Qing; Lian, Jianshe

    2008-09-01

    Bulk nanocrystalline Cu was synthesized by a pulse electric brush-plating technique. A very large strength (at 2% plastic strain) increase from 644 to 1451 MPa was obtained by compression tests at room temperature and strain rates from 1×10-5 to 3×100 s-1. A transition in plastic deformation mechanism with strain rate from a combination of the thermally activated grain boundary sliding and the dislocation emission-absorption in grain boundaries to one dominated by the dislocation activity has been revealed by the significant changes in strain rate sensitivity and apparent activation volume with strain rate.

  20. Ductile damage prediction in sheet and bulk metal forming

    NASA Astrophysics Data System (ADS)

    Badreddine, Houssem; Labergère, Carl; Saanouni, Khemais

    2016-04-01

    This paper is dedicated to the presentation of an advanced 3D numerical methodology for virtual sheet and/or bulk metal forming simulation to predict the anisotropic ductile defects occurrence. First, the detailed formulation of thermodynamically-consistent fully coupled and fully anisotropic constitutive equations is given. The proposed constitutive equations account for the main material nonlinearities as the anisotropic plastic flow, the mixed isotropic and kinematic hardening and the anisotropic ductile damage under large inelastic strains. Second, the related numerical aspects required to solve the initial and boundary value problem (IBVP) are very briefly presented in the framework of the 3D finite element method. The global resolution schemes as well as the local integration schemes of the fully coupled constitutive equations are briefly discussed. Finally, some typical examples of sheet and bulk metal forming processes are numerically simulated using the proposed numerical methodology.

  1. A hierarchically structured graphene foam and its potential as a large-scale strain-gauge sensor

    NASA Astrophysics Data System (ADS)

    Kuang, Jun; Liu, Luqi; Gao, Yun; Zhou, Ding; Chen, Zhuo; Han, Baohang; Zhang, Zhong

    2013-11-01

    A hierarchically structured thermal-reduced graphene (ReG) foam with 0.5 S cm-1 electrical conductivity is fabricated from a well-dispersed graphene oxide suspension via a directional freezing method followed by high-temperature thermal treatment. The as-prepared three-dimensional ReG foam has an ordered macroporous honeycomb-like structure with straight and parallel voids in the range of 30 μm to 75 μm separated by cell walls of several tens of nanometers thick. Despite its ultra-low density, the ReG foam has an excellent compression recovery along its in-plane direction. This property of the ReG foam can be attributed to its hierarchically porous structure, as demonstrated by the compression test. The excellent compression recovery and high conductivity provide the ReG foam with exceptional piezoresistive capabilities. The electrical resistance of the ReG foam shows a linearly decreasing trend with compressive strain increments of up to 60%, which cannot be observed in conventional rigid material-based sensors and carbon nanotube-based polymer sensors. Such intriguing linear strain-responsive behavior, along with the fast response time and high thermal stability, makes the ReG foam a promising candidate for strain sensing. We demonstrated that it could be used as a wearable device for real-time monitoring of human health.A hierarchically structured thermal-reduced graphene (ReG) foam with 0.5 S cm-1 electrical conductivity is fabricated from a well-dispersed graphene oxide suspension via a directional freezing method followed by high-temperature thermal treatment. The as-prepared three-dimensional ReG foam has an ordered macroporous honeycomb-like structure with straight and parallel voids in the range of 30 μm to 75 μm separated by cell walls of several tens of nanometers thick. Despite its ultra-low density, the ReG foam has an excellent compression recovery along its in-plane direction. This property of the ReG foam can be attributed to its hierarchically

  2. ROTARY BULK SOLIDS DIVIDER

    DOEpatents

    Maronde, Carl P.; Killmeyer JR., Richard P.

    1992-03-03

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  3. Rotary bulk solids divider

    DOEpatents

    Maronde, Carl P.; Killmeyer, Jr., Richard P.

    1992-01-01

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  4. Bulk Fuel Man.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by bulk fuel workers. Addressed in the four individual units of the course are the following topics: bulk fuel equipment, bulk fuel systems, procedures for handling fuels, and…

  5. On the development of explicit robust schemes for implementation of a class of hyperelastic models in large-strain analysis of rubbers

    NASA Technical Reports Server (NTRS)

    Saleeb, A. F.; Chang, T. Y. P.; Arnold, S. M.

    1992-01-01

    The issue of developing effective and robust schemes to implement a class of the Ogden-type hyperelastic constitutive models, for large-strain analysis of rubber-like materials, is addressed. To this end, explicit forms for the corresponding material tangent-stiffness tensors are developed, and these are valid for the entire deformation range; i.e., with both distinct as well as repeated principal-stretch values. Throughout the analysis the various implications of the underlying property of separability of the strain-energy functions are exploited, thus leading to compact final forms of the tensor expressions. In particular, this facilitated the treatment of the complex cases of uncoupled volumetric/deviatoric formulations for incompressible materials, which are becoming increasingly popular in recent years. The forms derived are also amenable for use with symbolic-manipulation packages for systematic code generation.

  6. A Large Portion of Meningococcal Antigen Typing System-Negative Meningococcal Strains from Spain Is Killed by Sera from Adolescents and Infants Immunized with 4CMenB

    PubMed Central

    Biolchi, A.; Moschioni, M.; Giuliani, M. M.; Pizza, M.; Vázquez, J. A.

    2015-01-01

    A new vaccine (the 4CMenB 4-component protein vaccine [Bexsero], which includes PorA, factor H-binding protein [fHbp], neisserial heparin-binding antigen [NHBA], and Neisseria adhesin A [NadA]) against serogroup B meningococci has recently been approved for use in people older than age 2 months in Europe, Australia, and Canada. Preapproval clinical efficacy studies are not feasible for invasive meningococcal disease because its incidence is low/very low, and the serum bactericidal antibody (SBA) titer (or the human SBA [hSBA] titer when human complement is used in the assay) has been used as a surrogate marker of protection. However, the hSBA assay cannot be used on a large scale, and therefore, a meningococcal antigen typing system (MATS) was developed. MATS combines conventional PorA genotyping with an enzyme-linked immunosorbent assay (ELISA) that quantifies both the expression and the cross-reactivity of antigenic variants. The assay has been used to evaluate the potential of the 4CMenB meningococcal group B vaccine to cover group B strains in several countries. Some recent data suggest that MATS is a conservative predictor of strain coverage. We used pooled sera from adolescents and infants to test by the hSBA assay 10 meningococcal group B strains isolated in Spain that were negative for the 3 antigens (n = 9) or that had very low levels of the 3 antigens (n = 1) by MATS. We found that all strains were killed by sera from adolescents and that 5 of the 10 strains were also killed, although at a low titer, by sera from infants. Our data confirm that MATS underestimates vaccine coverage. PMID:25630407

  7. A large portion of meningococcal antigen typing system-negative meningococcal strains from spain is killed by sera from adolescents and infants immunized with 4CMenB.

    PubMed

    Abad, R; Biolchi, A; Moschioni, M; Giuliani, M M; Pizza, M; Vázquez, J A

    2015-04-01

    A new vaccine (the 4CMenB 4-component protein vaccine [Bexsero], which includes PorA, factor H-binding protein [fHbp], neisserial heparin-binding antigen [NHBA], and Neisseria adhesin A [NadA]) against serogroup B meningococci has recently been approved for use in people older than age 2 months in Europe, Australia, and Canada. Preapproval clinical efficacy studies are not feasible for invasive meningococcal disease because its incidence is low/very low, and the serum bactericidal antibody (SBA) titer (or the human SBA [hSBA] titer when human complement is used in the assay) has been used as a surrogate marker of protection. However, the hSBA assay cannot be used on a large scale, and therefore, a meningococcal antigen typing system (MATS) was developed. MATS combines conventional PorA genotyping with an enzyme-linked immunosorbent assay (ELISA) that quantifies both the expression and the cross-reactivity of antigenic variants. The assay has been used to evaluate the potential of the 4CMenB meningococcal group B vaccine to cover group B strains in several countries. Some recent data suggest that MATS is a conservative predictor of strain coverage. We used pooled sera from adolescents and infants to test by the hSBA assay 10 meningococcal group B strains isolated in Spain that were negative for the 3 antigens (n = 9) or that had very low levels of the 3 antigens (n = 1) by MATS. We found that all strains were killed by sera from adolescents and that 5 of the 10 strains were also killed, although at a low titer, by sera from infants. Our data confirm that MATS underestimates vaccine coverage. PMID:25630407

  8. Structure of the exceptionally large nonrepetitive carbohydrate backbone of the lipopolysaccharide of Pectinatus frisingensis strain VTT E-82164.

    PubMed

    Vinogradov, Evgeny; Petersen, Bent O; Sadovskaya, Irina; Jabbouri, Said; Duus, Jens Ø; Helander, Ilkka M

    2003-07-01

    The structures of the oligosaccharides obtained after acetic acid hydrolysis and alkaline deacylation of the rough-type lipopolysaccharide (LPS) from Pectinatus frisingensis strain VTT E-82164 were analysed using NMR spectroscopy, MS and chemical methods. The LPS contains two major structural variants, differing by a decasaccharide fragment, and some minor variants lacking the terminal glucose residue. The largest structure of the carbohydrate backbone of the LPS that could be deduced from experimental results consists of 25 monosaccharides (including the previously found Ara4NP residue in lipid A) arranged in a well-defined nonrepetitive structure: We presume that the shorter variant with R1 = H represents the core-lipid A part of the LPS, and the additional fragment is present instead of the O-specific polysaccharide. Structures of this type have not been previously described. Analysis of the deacylation products obtained from the LPS of the smooth strain, VTT E-79100T, showed that it contains a very similar core but with one different glycosidic linkage. PMID:12846837

  9. Investigation of laser shock induced ductile damage at ultra-high strain rate by using large scale MD simulations

    NASA Astrophysics Data System (ADS)

    Cuq-Lelandais, Jean-Paul; Boustie, Michel; Soulard, Laurent; Berthe, Laurent; Bontaz-Carion, Joëlle; de Resseguier, Thibaut

    2011-06-01

    Laser driven shocks allow to investigate materials behavior at very high strain rate (107s-1) and presents a great interest for research applications. Microscopic simulations of ultra-short laser driven shock on micrometric Tantalum single-crystals have been performed by using the CEA-DAM Classical Molecular Dynamics code. This method, complementary to continuum models, provides an analysis the microscopic processes related to damage (ductile pore nucleation and growth) which occurs during spallation. This results are compared to spallation experiments data (VISAR signals, micro-tomography) obtained with the LULI100TW femtosecond laser in order to validate the MD behavior. Moreover, in the framework of a multi-scale approach, we show the possibility to use MD simulation to fit macroscopic damage models. This method is illustrated with an application to the parameters determination of the Kanel criterion. This also shows the high strain rates involved during damage process, around 109s-1, allow to approach the inter-atomic theoretical cohesion stress threshold.

  10. Investigation of laser shock induced ductile damage at ultra-high strain rate by using large scale MD simulations

    NASA Astrophysics Data System (ADS)

    Cuq-Lelandais, Jean-Paul; Boustie, Michel; Soulard, Laurent; Berthe, Laurent; Bontaz-Carion, Joelle; de Resseguier, Thibaut

    2012-03-01

    Laser driven shocks allow an investigation of materials behavior at very high strain rate (107s-1) and present a great interest for research applications. Microscopic simulations of ultra-short laser driven shock on micrometric Tantalum single-crystals have been performed by using the CEADAM Classical Molecular Dynamics code. This method, complementary to continuum models, provides an analysis the microscopic processes related to damage (ductile pore nucleation and growth) which occurs during spallation. These results are compared to spallation experimental data (VISAR signals, micro-tomography) obtained with the LULI100TW femtosecond laser in order to validate the MD behavior. Moreover, in the framework of a multi-scale approach, we show the possibility to use MD simulation to fit macroscopic damage models. This method is illustrated with an application to the parameters determination of Kanel damage model parameters. This also shows the high strain rates involved during damage process, around 109s-1, can approach the inter-atomic theoretical cohesion stress threshold.

  11. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  12. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  13. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  14. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  15. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  16. SISGR -- Domain Microstructures and Mechanisms for Large, Reversible and Anhysteretic Strain Behaviors in Phase Transforming Ferroelectric Materials

    SciTech Connect

    Wang, Yu U.

    2013-12-06

    This four-year project (including one-year no-cost extension) aimed to advance fundamental understanding of field-induced strain behaviors of phase transforming ferroelectrics. We performed meso-scale phase field modeling and computer simulation to study domain evolutions, mechanisms and engineering techniques, and developed computational techniques for nanodomain diffraction analysis; to further support above originally planned tasks, we also carried out preliminary first-principles density functional theory calculations of point defects and domain walls to complement meso-scale computations as well as performed in-situ high-energy synchrotron X-ray single crystal diffraction experiments to guide theoretical development (both without extra cost to the project thanks to XSEDE supercomputers and DOE user facility Advanced Photon Source).

  17. Repeated large-magnitude earthquakes in a tectonically active, low-strain continental interior: The northern Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Landgraf, A.; Dzhumabaeva, A.; Abdrakhmatov, K. E.; Strecker, M. R.; Macaulay, E. A.; Arrowsmith, Jr.; Sudhaus, H.; Preusser, F.; Rugel, G.; Merchel, S.

    2016-05-01

    The northern Tien Shan of Kyrgyzstan and Kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries. To assess the significance of such a pulse of strain release in a continental interior, it is important to analyze and quantify strain release over multiple time scales. We have undertaken paleoseismological investigations at two geomorphically distinct sites (Panfilovkoe and Rot Front) near the Kyrgyz capital Bishkek. Although located near the historic epicenters, both sites were not affected by these earthquakes. Trenching was accompanied by dating stratigraphy and offset surfaces using luminescence, radiocarbon, and 10Be terrestrial cosmogenic nuclide methods. At Rot Front, trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years. The scarp rather resembles an extensive debris-flow lobe. At Panfilovkoe, we estimate a Late Pleistocene minimum slip rate of 0.2 ± 0.1 mm/a, averaged over at least two, probably three earthquake cycles. Dip-slip reverse motion along segmented, moderately steep faults resulted in hanging wall collapse scarps during different events. The most recent earthquake occurred around 3.6 ± 1.3 kyr ago (1σ), with dip-slip offsets between 1.2 and 1.4 m. We calculate a probabilistic paleomagnitude to be between 6.7 and 7.2, which is in agreement with regional data from the Kyrgyz range. The morphotectonic signals in the northern Tien Shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer-term coevolution of topography and seismogenic processes in similar structural settings worldwide.

  18. Growth of Si Bulk Crystals with Large Diameter Ratio Using Small Crucibles by Creating a Large Low-Temperature Region Inside a Si Melt Contained in an NOC Furnace Developed Using Two Zone Heaters

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo; Ono, Satoshi; Murai, Ryota; Kaneko, Yuzuru

    2016-06-01

    Three zone heaters were generally used for a noncontact crucible (NOC) furnace. For practical reasons a simpler NOC furnace was developed with two zone heaters, which had a carbon heat holder to cover the three roles of each heater. Large low-temperature regions were obtained, and silicon ingots were grown in small crucibles with a large diameter and diameter ratio. Here, the diameter ratio is the ratio of the ingot diameter to the crucible diameter and can be as large as 0.90. The diameter ratio was controlled mainly by the temperature reduction of the first heater. Power changes of the second heater did not have a significant impact on the ingot diameter. Using this NOC furnace, maximum ingot diameters of 28.0, 33.5, and 45.0 cm were obtained using crucibles of 33, 40, and 50 cm in diameter, respectively. The oxygen concentration of the ingots did not strongly depend on the diameter ratio and were always low because convection in the Si melt was markedly suppressed by the carbon heat holder. Moreover, the oxygen concentration of the ingots has a tendency to become lower as the crucible diameter becomes larger.

  19. Bulk Data Mover

    SciTech Connect

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections, data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/

  20. Colonization of the streptomycin-treated mouse large intestine by a human fecal Escherichia coli strain: role of growth in mucus.

    PubMed Central

    Wadolkowski, E A; Laux, D C; Cohen, P S

    1988-01-01

    The relative colonizing abilities of Escherichia coli F-18, isolated from the feces of a healthy human, and E. coli F-18col-, a strain derived from it which does not make the E. coli F-18 colicin, were studied. In a previous report, it was shown that when each strain was fed individually to streptomycin-treated mice, at approximately 10(10) CFU per mouse, each colonized the large intestine at between 10(7) and 10(8) CFU/g of feces indefinitely. However, when simultaneously fed to mice, although E. coli F-18 colonized at about 10(8) CFU/g of feces, E. coli F-18col- dropped to a level of 10(3) CFU/g of feces within 3 to 5 days. In the present investigation, we show that when given enough time to establish a state of colonization, E. coli F-18col- persists in feces in high numbers despite subsequent challenge by E. coli F-18. Therefore, a major defect in the ability of E. coli F-18col- to colonize in the presence of E. coli F-18 appears to be in initiating that state. In addition, when mucus was scraped from the cecal wall and, without further treatment, was inoculated with E. coli F-18 or F-18col-, both strains grew well. However, when cecal mucus was inoculated with both strains simultaneously, E. coli F-18 grew far more rapidly than E. coli F-18col-. Moreover, neither strain grew in cecal luminal contents. Together, these data suggest the possibility that both E. coli F-18 and F-18col- must grow in mucus to colonize the streptomycin-treated mouse large intestine, that E. coli F-18col- is eliminated by E. coli F-18 because it does not grow in mucus as well as E. coli F-18, and that E. coli F-18col- can resist elimination by E. coli F-18 if it is allowed enough time to establish itself within the mucus layer. PMID:3281898

  1. Large enhancement of bulk spin polarization by suppressing CoMn anti-sites in Co2Mn(Ge0.75Ga0.25) Heusler alloy thin film

    NASA Astrophysics Data System (ADS)

    Li, S.; Takahashi, Y. K.; Sakuraba, Y.; Tsuji, N.; Tajiri, H.; Miura, Y.; Chen, J.; Furubayashi, T.; Hono, K.

    2016-03-01

    We have investigated the structure and magneto-transport properties of Co2Mn(Ge0.75Ga0.25) (CMGG) Heusler alloy thin films with near-stoichiometric and Mn-rich compositions in order to understand the effect of Co-Mn anti-sites on bulk spin polarization. Anomalous x-ray diffraction measurements using synchrotron radiated x-rays confirmed that CoMn anti-sites easily form in the near-stoichiometric CMGG compound at annealing temperature higher than 400 °C, while it can be suppressed in Mn-rich CMGG films. Accordingly, large enhancement in negative anisotropic magnetoresistance of CMGG films and giant magnetoresistance (GMR) in current-perpendicular-to-plane (CPP) pseudo spin valves were observed in the Mn-rich composition. A large resistance-area product change (ΔRA) of 12.8 mΩ μm2 was demonstrated in the CPP-GMR pseudo spin valves using the Mn-rich CMGG layers after annealing at 600 °C. It is almost twice of the maximum output observed in the CPP-GMR pseudo spin valves using the near-stoichiometric CMGG. These indicate that the spin polarization of CMGG is enhanced in the Mn-rich composition through suppressing the formation of CoMn-antisites in CMGG films, being consistent with first-principle calculation results.

  2. Determination and mitigation of the uncertainty of neutron diffraction measurements of residual strain in large-grained polycrystalline material

    PubMed Central

    Holden, Tom M.; Traore, Yeli; James, Jon; Kelleher, Joe; Bouchard, P. John

    2015-01-01

    For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume. PMID:25844082

  3. Numerical calculation of thermo-mechanical problems at large strains based on complex step derivative approximation of tangent stiffness matrices

    NASA Astrophysics Data System (ADS)

    Balzani, Daniel; Gandhi, Ashutosh; Tanaka, Masato; Schröder, Jörg

    2015-05-01

    In this paper a robust approximation scheme for the numerical calculation of tangent stiffness matrices is presented in the context of nonlinear thermo-mechanical finite element problems and its performance is analyzed. The scheme extends the approach proposed in Kim et al. (Comput Methods Appl Mech Eng 200:403-413, 2011) and Tanaka et al. (Comput Methods Appl Mech Eng 269:454-470, 2014 and bases on applying the complex-step-derivative approximation to the linearizations of the weak forms of the balance of linear momentum and the balance of energy. By incorporating consistent perturbations along the imaginary axis to the displacement as well as thermal degrees of freedom, we demonstrate that numerical tangent stiffness matrices can be obtained with accuracy up to computer precision leading to quadratically converging schemes. The main advantage of this approach is that contrary to the classical forward difference scheme no round-off errors due to floating-point arithmetics exist within the calculation of the tangent stiffness. This enables arbitrarily small perturbation values and therefore leads to robust schemes even when choosing small values. An efficient algorithmic treatment is presented which enables a straightforward implementation of the method in any standard finite-element program. By means of thermo-elastic and thermo-elastoplastic boundary value problems at finite strains the performance of the proposed approach is analyzed.

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

    NASA Astrophysics Data System (ADS)

    Al-Jabr, A. A.; Majid, M. A.; Alias, M. S.; Anjum, D. H.; Ng, T. K.; Ooi, B. S.

    2016-04-01

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

  5. Lifelong Cyclic Mechanical Strain Promotes Large Elastic Artery Stiffening: Increased Pulse Pressure and Old Age-Related Organ Failure.

    PubMed

    Thorin-Trescases, Nathalie; Thorin, Eric

    2016-05-01

    The arterial wall is under a huge mechanical constraint imposed by the cardiac cycle that is bound to generate damage with time. Each heartbeat indeed imposes a pulsatile pressure that generates a vascular stretch. Lifetime accumulation of pulsatile stretches will eventually induce fatigue of the elastic large arterial walls, such as aortic and carotid artery walls, promoting their stiffening that will gradually perturb the normal blood flow and local pressure within the organs, and lead to organ failure. The augmented pulse pressure induced by arterial stiffening favours left ventricular hypertrophy because of the repeated extra work against stiff high-pressure arteries, and tissue damage as a result of excessive pulsatile pressure transmitted into the microcirculation, especially in low resistance/high-flow organs such as the brain and kidneys. Vascular aging is therefore characterized by the stiffening of large elastic arteries leading to a gradual increase in pulse pressure with age. In this review we focus on the effect of age-related stiffening of large elastic arteries. We report the clinical evidence linking arterial stiffness and organ failure and discuss the molecular pathways that are activated by the increase of mechanical stress in the wall. We also discuss the possible interventions that could limit arterial stiffening with age, such as regular aerobic exercise training, and some pharmacological approaches. PMID:26961664

  6. Large-scale purification and characterization of dihydrofolate reductase from a methotrexate-resistant strain of Lactobacillus casei.

    PubMed Central

    Dann, J G; Ostler, G; Bjur, R A; King, R W; Scudder, P; Turner, P C; Roberts, G C; Burgen, A S

    1976-01-01

    Dihydrofolate reductase has been purified from a methotrexate-resistant strain of Lactobacillus casei NCB 6375. By careful attention to growth conditions, up to 2.5 g of enzyme is obtained from a 400 litre culture. The purification procedure, involving poly-ethyleneimine treatment, DEAE-cellulose chromatography and affinity chromatography on methotrexate-aminohexyl-Sepharose, operates on the gram scale, with overall yields of 50-60%. Elution of the affinity column by reverse (upward) flow was used, as it led to recovery of the enzyme in a much smaller volume. The enzyme obtained appears to be more than 98% pure, as judged by gel electrophoresis, isoelectric focusing, and gel filtration. It has a mol.wt. of approx. 17900 and a turnover number of 4s-1 (50mM-triethanolamine/400mM-KCl, pH 7.2, 25 degrees C) with dihydrofolate and NADPH as substrates. The turnover number for folate is 0.02s-1. Michaelis constants for a variety of substrates have been measured by using a new fluorimetric assay (0.36 muM-dihydrofolate; 0.78 muM-NADPH), and binding constants determined by using the quenching of protein fluorescence (dihydrofolate, 2.25 X 10(6)M-1; NADPH, greater than 10(8)M-1). The pH/activity profile shows a single maximum at pH 7.3; at this pH, marked activation by 0.5M-NaCl is observed. PMID:10886

  7. [Assessment of job strain and its consequencies in a large public organisation. Findings from the SEMM Study].

    PubMed

    Ferrario, M M; Cimmino, L; Ganna, A; Cambiano, V; Borchini, R; Cesana, G

    2008-01-01

    The demand-control model originally developed by Robert Karasek is in Italy the preferred tool to investigate perceived work stress due to work-related organizational constrains. We wish to report the comprehensive results of the SEMM Study, carried on a wide sample of civil servants. N. 5271 women and 2601 men, employed at the Municipality of Milan in the years 1991-1996 were enrolled into the study. The overall participation rate was high in both gender group (75% or more), indicating a good compliance of employees for health prevention programmes carried out in work settings. Each participant, who has given consent, in addition to the medical examinations and biological tests related to the investigation of work exposures, underwent to a structured procedure to measure cardiovascular risk factors, according to the methods developed in the WHO MONICA Project, job strain adopting the Job Content Questionnaire (JCQ), and the Baecke Questionnaire to investigate major quotes of physical activity. In this contest the JCQ has shown an acceptable level of internal and external consistency as well as of acceptance, measured by employees compliance. Psychological job demand and decision latitude can be assessed with two different JCQ revisions available in Italian, which were validated with the contribution of the author, at different complexity, but with comparable results of weighted scores. For a comprehensive assessment of the working conditions social support at work is also of relevance. In the work public sector considered, the JCQ major scores resulted to be valid descriptors of key aspects of the work organization. The concurrent assessment of sick leaves, known marker of burnout, allows to identify work- and individual-related determinants and, in a specific work setting, to give indications for coping actions which may improve workers' integration. In addition, the assessment of cardiovascular risk factors, carried out with standardised and then reliable

  8. Microstructure and mechanical properties of a large-dimensional bulk nanocrystalline-based Fe-Al-Cr alloy prepared by an aluminothermic reaction casting and followed annealing at 1000 °C

    NASA Astrophysics Data System (ADS)

    La, Peiqing; Wang, Hongding; Liu, Xuemei; Wei, Yupeng; Jiao, Huisheng

    2013-06-01

    A large-dimensional bulk nanocrystalline phase-based Fe-Al-Cr alloy with 10 wt.% Cr, which was about 200 mm in diameter and 10 mm in thickness, was prepared by an aluminothermic reaction casting and followed annealing at 1000 °C. Microstructures of the alloy were investigated by optical microscope, electron probe microscope, scanning electron microscope attached with electron backscattered diffraction, X-ray diffraction and transmission electron microscope. The magnetization curves of the alloy were tested by Lake Shore 7410 vibrating sample magnetometer. Compressive properties of the alloy were tested. The results show the alloy was consisted of a Fe-Al-Cr nanocrystalline matrix, Cr7C3 phase and contaminants in micrometre. Average grain size of the nanocrystalline matrix was 19 nm. Volume fraction of the Cr7C3 phase in the alloy was about 4.5%. After annealing, the saturated intensity of magnetization and the specific magnetic susceptibility of the alloy increased slightly from 99 emu/g and 0.083 emu/g Oe to 104 emu/g and 0.113 emu/g Oe, respectively. Compressive strength of the alloy was 1200 MPa and much higher than that of the small-scale nanocrystalline alloy and alloy with grains in micrometre.

  9. Bulk Data Mover

    Energy Science and Technology Software Center (ESTSC)

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections,more » data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/« less

  10. Analysis of Surface and Bulk Behavior in Ni-Pd Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Rondald D.

    2003-01-01

    The most salient features of the surface structure and bulk behavior of Ni-Pd alloys have been studied using the BFS method for alloys. Large-scale atomistic simulations were performed to investigate surface segregation profiles as a function of temperature, crystal face, and composition. Pd enrichment of the first layer was observed in (111) and (100) surfaces, and enrichment of the top two layers occurred for (110) surfaces. In all cases, the segregation profile shows alternate planes enriched and depleted in Pd. In addition, the phase structure of bulk Ni-Pd alloys as a function of temperature and composition was studied. A weak ordering tendency was observed at low temperatures, which helps explain the compositional oscillations in the segregation profiles. Finally, based on atom-by-atom static energy calculations, a comprehensive explanation for the observed surface and bulk features will be presented in terms of competing chemical and strain energy effects.

  11. Strain-induced properties of epitaxial VOx thin films

    NASA Astrophysics Data System (ADS)

    Rata, A. D.; Hibma, T.

    2005-01-01

    We have grown VOx thin films on different substrates in order to investigate the influence of epitaxial strain on the transport properties. We found that the electric conductivity is much larger for films grown under compressive strain on SrTiO3 substrates, as compared to bulk material and VOx films grown under tensile strain on MgO substrates. A clear crossover from metallic to semiconducting behavior is observed when increasing the oxygen content x. Apparently, the application of strain induces a Mott-Hubbard insulator-to-metal transition in VOx<1. The VOx/SrTiO3 films show an unexpected large positive magnetoresistance effect at low temperatures, which is not found in the VOx films grown under tensile strain on MgO or on a substrate with a similar lattice parameter.

  12. A facile method to prepare large quantities of active caspase-3 overexpressed by auto-induction in the C41(DE3) strain.

    PubMed

    Hwang, Dohyeon; Kim, Sang Ah; Yang, Eun Gyeong; Song, Hyun Kyu; Chung, Hak Suk

    2016-10-01

    Since human Caspase-3, a member of the cysteine protease family, plays important roles not only in the apoptosis pathway as an executioner protein, but also in neurological disorders as a critical factor, biomedical researchers have been interested in the development of modulators of caspase-3 activity. Such studies require large quantities of purified active caspase-3. So far, purification of soluble caspase-3 from full-length human caspase-3 in Escherichia coli (E. coli) yields only several mg from a liter of culture media. Therefore, a number of alternative strategies to purify active caspase-3 have been described in the literature, including refolding and protein engineering. In this study, we systematically study the effects of host E. coli strains and growth conditions on purifications of active caspase-3 from full-length human caspase-3. Using a combination of conditions that include use of the C41(DE3) strain, low-temperature expression, and auto-induction that induces caspase-3 expression depending on metabolic state of the individual host cell, we are able to obtain 14-17 mg caspase-3 per liter of culture, an amount that is about 7 times larger than published results. This optimized expression and purification method for caspase-3 can be easily scaled up to facilitate the demand for active enzyme. PMID:27320415

  13. Load partitioning between single bulk grains in a two-phase duplex stainless steel during tensile loading.

    SciTech Connect

    Hedstrom, P.; Han, T. S.; Lienert, U.; Almer, J. D.; Oden, M.; X-Ray Science Division; Lulea Univ.; Royal Inst. of Tech.; Yonsei Univ.; Linkoping Univ.

    2010-01-01

    The lattice strain tensor evolution for single bulk grains of austenite and ferrite in a duplex stainless steel during tensile loading to 0.02 applied strain has been investigated using in situ high-energy X-ray measurements and finite-element modeling. Single-grain X-ray diffraction lattice strain data for the eight austenite and seven ferrite grains measured show a large variation of residual lattice strains, which evolves upon deformation to the point where some grains with comparable crystallographic orientations have lattice strains different by 1.5 x 10{sup -3}, corresponding to a stress of -300MPa. The finite-element simulations of the 15 measured grains in three different spatial arrangements confirmed the complex deformation constraint and importance of local grain environment.

  14. Powder metallurgy processing and deformation characteristics of bulk multimodal nickel

    SciTech Connect

    Farbaniec, L.; Dirras, G.; Krawczynska, A.; Mompiou, F.; Couque, H.; Naimi, F.; Bernard, F.; Tingaud, D.

    2014-08-15

    Spark plasma sintering was used to process bulk nickel samples from a blend of three powder types. The resulting multimodal microstructure was made of coarse (average size ∼ 135 μm) spherical microcrystalline entities (the core) surrounded by a fine-grained matrix (average grain size ∼ 1.5 μm) or a thick rim (the shell) distinguishable from the matrix. Tensile tests revealed yield strength of ∼ 470 MPa that was accompanied by limited ductility (∼ 2.8% plastic strain). Microstructure observation after testing showed debonding at interfaces between the matrix and the coarse entities, but in many instances, shallow dimples within the rim were observed indicating local ductile events in the shell. Dislocation emission and annihilation at grain boundaries and twinning at crack tip were the main deformation mechanisms taking place within the fine-grained matrix as revealed by in-situ transmission electron microscopy. Estimation of the stress from loop's curvature and dislocation pile-up indicates that dislocation emission from grain boundaries and grain boundary overcoming largely contributes to the flow stress. - Highlights: • Bulk multi-modal Ni was processed by SPS from a powder blend. • Ultrafine-grained matrix or rim observed around spherical microcrystalline entities • Yield strength (470 MPa) and ductility (2.8% plastic strain) were measured. • Debonding was found at the matrix/microcrystalline entity interfaces. • In-situ TEM showed twinning, dislocation emission and annihilation at grain boundaries.

  15. Bulk solitary waves in elastic solids

    NASA Astrophysics Data System (ADS)

    Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.

    2015-10-01

    A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the

  16. Quantum spin hall insulators in strain-modified arsenene

    NASA Astrophysics Data System (ADS)

    Zhang, Haijun; Ma, Yandong; Chen, Zhongfang

    2015-11-01

    By means of density functional theory (DFT) computations, we predict that the suitable strain modulation of honeycomb arsenene results in a unique two-dimensional (2D) topological insulator (TI) with a sizable bulk gap (up to 696 meV), which could be characterized and utilized at room temperature. Without considering any spin-orbit coupling, the band inversion occurs around the Gamma (G) point at tensile strains larger than 11.7%, which indicates the quantum spin Hall effect in arsenene at appropriate strains. The nontrivial topological phase was further confirmed by the topological invariant ν = 1 and edge states with a single Dirac-type crossing at the G point. Our results provide a promising strategy for designing 2D TIs with large bulk gaps from commonly used materials.By means of density functional theory (DFT) computations, we predict that the suitable strain modulation of honeycomb arsenene results in a unique two-dimensional (2D) topological insulator (TI) with a sizable bulk gap (up to 696 meV), which could be characterized and utilized at room temperature. Without considering any spin-orbit coupling, the band inversion occurs around the Gamma (G) point at tensile strains larger than 11.7%, which indicates the quantum spin Hall effect in arsenene at appropriate strains. The nontrivial topological phase was further confirmed by the topological invariant ν = 1 and edge states with a single Dirac-type crossing at the G point. Our results provide a promising strategy for designing 2D TIs with large bulk gaps from commonly used materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05006e

  17. The polarization signature of local bulk flows

    SciTech Connect

    Roebber, Elinore; Holder, Gilbert

    2014-02-01

    A large peculiar velocity of the intergalactic medium produces a Doppler shift of the cosmic microwave background with a frequency-dependent quadrupole term. This quadrupole will act as a source for polarization of the cosmic microwave background, creating a large-scale polarization anisotropy if the bulk flow is local and coherent on large scales. In the case where we are near the center of the moving region, the polarization signal is a pure quadrupole. We show that the signal is small, but detectable with future experiments for bulk flows as large as some recent reports.

  18. Phobos: Observed bulk properties

    NASA Astrophysics Data System (ADS)

    Pätzold, Martin; Andert, Tom; Jacobson, Robert; Rosenblatt, Pascal; Dehant, Véronique

    2014-11-01

    This work is a review of the mass determinations of the Mars moon Phobos by spacecraft close flybys, by solving for the Martian gravity field and by the analysis of secular orbit perturbations. The absolute value and accuracy is sensitive on the knowledge and accuracy of the Phobos ephemeris, of the spacecraft orbit, other perturbing forces acting on the spacecraft and the resolution of the Martian gravity field besides the measurement accuracy of the radio tracking data. The mass value and its error improved from spacecraft mission to mission or from the modern analysis of “old” tracking data but these solutions depend on the accuracy of the ephemeris at the time of observation. The mass value seems to settle within the range of GMPh=(7.11±0.09)×10-4 km3 s-2 which covers almost all mass values from close flybys and “distant” encounters within its 3-σ error (1.5%). Using the volume value determined from MEX HRSC imaging, the bulk density is (1873±31) kg m-3 (3-σ error or 1.7%), a low value which suggests that Phobos is either highly porous, is composed partially of light material or both. The determination of the gravity coefficients C20 and C22 from the Mars Express 2010 close flyby does not allow to draw conclusion on the internal structure. The large errors do not distinguish whether Phobos is homogeneous or not. In view of theories of the Phobos' origin, one possibility is that Phobos is not a captured asteroid but accreted from a debris disk in Mars orbit as a second generation solar system object.

  19. Large bulk soft magnetic [(Fe{sub 0.5}Co{sub 0.5}){sub 0.75}B{sub 0.20}Si{sub 0.05}]{sub 96}Nb{sub 4} glassy alloy prepared by B{sub 2}O{sub 3} flux melting and water quenching

    SciTech Connect

    Bitoh, T.; Makino, A.; Inoue, A.; Greer, A.L.

    2006-05-01

    The large bulk soft magnetic glassy [(Fe{sub 0.5}Co{sub 0.5}){sub 0.75}B{sub 0.20}Si{sub 0.05}]{sub 96}Nb{sub 4} alloy specimens with the diameters up to 7.7 mm have been prepared by water quenching the melt immersed in the molten flux of B{sub 2}O{sub 3}. The maximum diameter of the obtained specimens is approximately 1.5 times as large as the previous result for copper mold casting. The bulk specimen with 7.7 mm in diameter exhibits the saturation magnetization of 1.13 T, the coercivity lower than 20 A/m at room temperature, and the Curie temperature of 732 K. This bulk specimen is the thickest of any soft magnetic glassy alloys formed until now.

  20. Constraints on strain rates during large-scale mid-crustal shearing: An example from the basal Vaddas shear zone, northern Caledonides

    NASA Astrophysics Data System (ADS)

    Gasser, Deta; Stünitz, Holger; Nasipuri, Pritam; Menegon, Luca

    2013-04-01

    The Caledonian orogen in Scandinavia is characterized by large-scale crustal nappe stacks which were emplaced east-/southeast-wards onto the Baltica shield. Whereas original thrust relationships are generally obscured by syn- to post-collisional extensional deformation in the southern and central Scandinavian Caledonides, several large-scale thrust systems are well-preserved in the northern Scandinavian Caledonides in Troms and Finnmark. One example is the mid-crustal Vaddas shear zone, which emplaced the Vaddas nappe on top of the Kalak nappe complex. In this contribution we present a structural, petrological and geochronological analysis of the rocks under- and overlying the Vaddas shear zone in northern Troms, in order to estimate the strain rate associated with thrusting along this major shear zone. The Vaddas nappe above the investigated shear zone consists mainly of Upper Ordovician to Silurian metasediments, which were deposited in a marine environment and which were intruded by voluminous gabbroic intrusions, before they were sheared off from their substratum and transported on top of the Kalak nappe complex during the Caledonian orogeny. PT conditions from one of these gabbroic bodies indicate that the body intruded the metasediments at ~9 kbar (Getsinger et al., subm to G3), which corresponds to a depth of ~34 km. U-Pb SIMS dating of zircons from this gabbro indicate that intrusion occurred at 439±2 Ma. The Vaddas nappe is separated from the Kalak nappe by an at least ~150 m thick, amphibolite-facies shear zone with a subhorizontal fabric and top-to-the-SE shear sense. It has developed within the lowest part of the Vaddas nappe as well as the upper part of the Kalak nappe complex and PT calculations indicate that final shearing occurred at ~450° C and ~6 kbar (depth of ~23 km). U-Pb TIMS dating of titanites, which grow parallel to the shear fabric in the Kalak nappe complex, gives 206Pb/238U ages ranging from 442±1 to 429±1 Ma, indicating that

  1. Bulk viscosity of a pion gas

    NASA Astrophysics Data System (ADS)

    Lu, Egang; Moore, Guy D.

    2011-04-01

    We compute the bulk viscosity of a gas of pions at temperatures below the QCD crossover temperature, for the physical value of mπ, to lowest order in chiral perturbation theory. Bulk viscosity is controlled by number-changing processes which become exponentially slow at low temperatures when the pions become exponentially dilute, leading to an exponentially large bulk viscosity ζ~(F08/mπ5)exp(2mπ/T), where F0≃93MeV is the pion decay constant.

  2. Structural features of plastic deformation in bulk metallic glasses

    SciTech Connect

    Scudino, S. Shakur Shahabi, H.; Stoica, M.; Kühn, U.; Kaban, I.; Escher, B.; Eckert, J.; Vaughan, G. B. M.

    2015-01-19

    Spatially resolved strain maps of a plastically deformed bulk metallic glass (BMG) have been created by using high-energy X-ray diffraction. The results reveal that plastic deformation creates a spatially heterogeneous atomic arrangement, consisting of strong compressive and tensile strain fields. In addition, significant shear strain is introduced in the samples. The analysis of the eigenvalues and eigenvectors of the strain tensor indicates that considerable structural anisotropy occurs in both the magnitude and direction of the strain. These features are in contrast to the behavior observed in elastically deformed BMGs and represent a distinctive structural sign of plastic deformation in metallic glasses.

  3. Microstructural evolution during strain localization in dolomite aggregates

    NASA Astrophysics Data System (ADS)

    Holyoke, Caleb W.; Kronenberg, Andreas K.; Newman, Julie

    2014-12-01

    Dolomite aggregates deformed by dislocation creep over a wide range of conditions (T = 700-1000 °C, effective pressure of 900 MPa, strain rates of 10-7 - 10-4/s) strain weaken by up to 75% of the peak differential stress. Microstructural study of samples shortened to different finite strains beyond the peak differential stress shows that strain becomes highly localized within shear zones by high-temperature creep processes, with no contribution of brittle cracking. At low strains (8%), dolomite deforms homogeneously by recrystallization-accommodated dislocation creep. At progressively higher sample strains, deformation is localized into narrow shear zones made up of very fine (˜3 μm) recrystallized grains and relict porphyroclasts (20-100 μm). Finely-recrystallized dolomite grains in the shear zones are largely dislocation free and localized shear is facilitated by diffusion creep. In contrast, original dolomite grains and porphyroclasts in shear zones have high dislocation densities and do not deform after shear zone formation. Calculated strain rates in the shear zones are two to three orders of magnitude faster than the imposed bulk strain rate of the samples and these strain rates are consistent with predictions of the diffusion creep flow law for fine-grained dolomite.

  4. Bulk electroporation of retinal ganglion cells in live Xenopus tadpoles.

    PubMed

    Ruthazer, Edward S; Schohl, Anne; Schwartz, Neil; Tavakoli, Aydin; Tremblay, Marc; Cline, Hollis T

    2013-08-01

    Individual neurons in the developing nervous system of Xenopus laevis can be visualized by the targeted delivery of a fluorophore. The fluorophore can be delivered as a fluorescent dye or DNA that encodes a fluorescent protein. Local iontophoresis is a method that works well for transfer of fluorescent dye to retinal ganglion cells (RGCs) in the eye, but it does not give a high yield for delivery of DNA. This is largely because the degree of pigmentation of the eyes, even in albino strains, makes it difficult to visualize RGC somata during pipette positioning. Bulk retinal electroporation is a better approach for delivery of plasmid DNA to RGC. The method described here works best in tadpoles older than stage 42. PMID:23906915

  5. Three-dimensional, extended field-of-view ultrasound method for estimating large strain mechanical properties of the cervix during pregnancy.

    PubMed

    House, Michael; Feltovich, Helen; Hall, Timothy J; Stack, Trevor; Patel, Atur; Socrate, Simona

    2012-01-01

    Cervical shortening and cervical insufficiency contribute to a significant number of preterm births. However, the deformation mechanisms that control how the cervix changes its shape from long and closed to short and dilated are not clear. Investigation of the biomechanical problem is limited by (1) lack of thorough characterization of the three-dimensional anatomical changes associated with cervical deformation and (2) difficulty measuring cervical tissue properties in vivo. The objective of the present study was to explore the feasibility of using three-dimensional ultrasound and fundal pressure to obtain anatomically-accurate numerical models of large-strain cervical deformation during pregnancy and enable noninvasive assessment of cervical-tissue compliance. Healthy subjects (n = 6) and one subject with acute cervical insufficiency in the midtrimester were studied. Extended field-of-view ultrasound images were obtained of the entire uterus and cervix. These images aided construction of anatomically accurate numerical models. Cervical loading was achieved with fundal pressure, which was quantified with a vaginal pressure catheter. In one subject, the anatomical response to fundal pressure was matched by a model-based simulation of the deformation response, thereby deriving the corresponding cervical mechanical properties and showing the feasibility of noninvasive assessment of compliance. The results of this pilot study demonstrate the feasibility of a biomechanical modeling framework for estimating cervical mechanical properties in vivo. An improved understanding of cervical biomechanical function will clarify the pathophysiology of cervical shortening. PMID:22655487

  6. Analysis of pressure-strain and pressure gradient-scalar covariances in cloud-topped boundary layers: A large-eddy simulation study

    NASA Astrophysics Data System (ADS)

    Heinze, Rieke; Mironov, Dmitrii; Raasch, Siegfried

    2016-03-01

    A detailed analysis of the pressure-scrambling terms (i.e., the pressure-strain and pressure gradient-scalar covariances) in the Reynolds-stress and scalar-flux budgets for cloud-topped boundary layers (CTBLs) is performed using high-resolution large-eddy simulation (LES). Two CTBLs are simulated — one with trade wind shallow cumuli, and the other with nocturnal marine stratocumuli. The pressure-scrambling terms are decomposed into contributions due to turbulence-turbulence interactions, mean velocity shear, buoyancy, and Coriolis effects. Commonly used models of these contributions, including a simple linear model most often used in geophysical applications and a more sophisticated two-component-limit (TCL) nonlinear model, are tested against the LES data. The decomposition of the pressure-scrambling terms shows that the turbulence-turbulence and buoyancy contributions are most significant for cloud-topped boundary layers. The Coriolis contribution is negligible. The shear contribution is generally of minor importance inside the cloudy layers, but it is the leading-order contribution near the surface. A comparison of models of the pressure-scrambling terms with the LES data suggests that the more complex TCL model is superior to the simple linear model only for a few contributions. The linear model is able to reproduce the principal features of the pressure-scrambling terms reasonably well. It can be applied in the second-order turbulence modeling of cloud-topped boundary layer flows, provided some uncertainties are tolerated.

  7. A three-dimensional, extended field of view ultrasound method for estimating large strain mechanical properties of the cervix during pregnancy

    PubMed Central

    House, Michael; Feltovich, Helen; Hall, Timothy J; Stack, Trevor; Patel, Atur; Socrate, Simona

    2015-01-01

    Cervical shortening and cervical insufficiency contribute to a significant number of preterm births. However, the deformation mechanisms that control how the cervix changes its shape from long and closed to short and dilated are not clear. Investigation of the biomechanical problem is limited by 1) lack of thorough characterization of the three-dimensional anatomical changes associated with cervical deformation and 2) difficulty measuring cervical tissue properties in vivo. The objective of the present study was to explore the feasibility of using three-dimensional ultrasound and fundal pressure to obtain anatomically accurate numerical models of large-strain cervical deformation during pregnancy and enable non-invasive assessment of cervical tissue compliance. Healthy subjects (n=6) and one subject with acute cervical insufficiency in the midtrimester were studied. Extended field of view ultrasound images were obtained of the entire uterus and cervix. These images aided construction of anatomically accurate numerical models. Cervical loading was achieved with fundal pressure, which was quantified with a vaginal pressure catheter. In one subject, the anatomical response to fundal pressure was matched by a model-based simulation of the deformation response, thereby deriving the corresponding cervical mechanical properties and showing the feasibility of non-invasive assessment of compliance. The results of this pilot study demonstrate the feasibility of a biomechanical modeling framework for estimating cervical mechanical properties in vivo. An improved understanding of cervical biomechanical function will clarify the pathophysiology of cervical shortening. PMID:22655487

  8. Organization of a large gene cluster encoding ribosomal proteins in the cyanobacterium Synechococcus sp. strain PCC 6301: comparison of gene clusters among cyanobacteria, eubacteria and chloroplast genomes.

    PubMed

    Sugita, M; Sugishita, H; Fujishiro, T; Tsuboi, M; Sugita, C; Endo, T; Sugiura, M

    1997-08-11

    The structure of a large gene cluster containing 22 ribosomal protein (r-protein) genes of the cyanobacterium Synechococcus sp. strain PCC6301 is presented. Based on DNA and protein sequence analyses, genes encoding r-proteins L3, L4, L23, L2, S19, L22, S3, L16, L29, S17, L14, L24, L5, S8, L6, L18, S5, L15, L36, S13, S11, L17, SecY, adenylate kinase (AK) and the alpha subunit of RNA polymerase were identified. The gene order is similar to that of the E. coli S10, spc and alpha operons. Unlike the corresponding E. coli operons, the genes for r-proteins S4, S10, S14 and L30 are not present in this cluster. The organization of Synechococcus r-protein genes also resembles that of chloroplast (cp) r-protein genes of red and brown algal species. This strongly supports the endosymbiotic theory that the cp genome evolved from an ancient photosynthetic bacterium. PMID:9300823

  9. Hydrogels: DNA bulks up

    NASA Astrophysics Data System (ADS)

    Labean, Thom

    2006-10-01

    Since the 1940s DNA has been known as the genetic material connected to heredity, and from the early 1980s it has also been considered as a potential structural material for nanoscale construction. Now, a hydrogel made entirely of DNA brings this molecule into the realm of bulk materials.

  10. Reversible Modulation of Spontaneous Emission by Strain in Silicon Nanowires

    PubMed Central

    Shiri, Daryoush; Verma, Amit; Selvakumar, C. R.; Anantram, M. P.

    2012-01-01

    We computationally study the effect of uniaxial strain in modulating the spontaneous emission of photons in silicon nanowires. Our main finding is that a one to two orders of magnitude change in spontaneous emission time occurs due to two distinct mechanisms: (A) Change in wave function symmetry, where within the direct bandgap regime, strain changes the symmetry of wave functions, which in turn leads to a large change of optical dipole matrix element. (B) Direct to indirect bandgap transition which makes the spontaneous photon emission to be of a slow second order process mediated by phonons. This feature uniquely occurs in silicon nanowires while in bulk silicon there is no change of optical properties under any reasonable amount of strain. These results promise new applications of silicon nanowires as optoelectronic devices including a mechanism for lasing. Our results are verifiable using existing experimental techniques of applying strain to nanowires. PMID:22708056

  11. Faecal bulking efficacy of Australasian breakfast cereals.

    PubMed

    Monro, John A

    2002-01-01

    Faecal bulk may play an important role in preventing a range of disorders of the large bowel, but as yet there is little information available on the relative faecal bulking capacities of various foods. Breakfast cereals are often promoted as a good source of potential bulk for 'inner health' because they provide dietary fibre, but their relative abilities to provide faecal bulk per se have not been described. The faecal bulking efficacy of 28 representative Australasian breakfast cereals was therefore measured. A rat model developed for the purpose, and shown to give similar responses as humans to cereal fibres, was used to measure faecal bulking efficacy as increases in fully hydrated faecal weight/100 g diet, based on precise measurements of food intake, faecal dry matter output and faecal water-holding capacity (g water held without stress/g faecal dry matter). Compared to a baseline diet containing 50% sucrose, increments in hydrated faecal weight due to 50% breakfast cereal ranged from slightly negative (Cornflakes, -2 g/100 g diet) to about 80 g/100 g diet (San Bran). Most breakfast cereals increased hydrated faecal weight by between 10 and 20 g/100 g diet from a baseline of 21 +/- 1.5 g/100 g diet, but four products containing high levels of wheat bran had an exceptionally large impact on hydrated faecal weight (increment > 20 g/100 g diet), and the changes resulted more from relative changes in dry matter output than in faecal water retention/gram. However, as faecal water retention was about 2.5 g water/g faecal dry matter on average, increases in dry matter represented large increases in faecal water load. Faecal bulking indices (FBI) for most of the breakfast cereals were less than 20 (wheat bran = 100). The content of wheat bran equivalents for faecal bulk (WBE(fb)) in the breakfast cereals was calculated from FBI. Most breakfast cereals contributed, per serve, less than 10% of a theoretical daily reference value for faecal bulk (DRV(fb) = 63 WBE

  12. Emergence and dissemination of a highly vancomycin-resistant vanA strain of Enterococcus faecium at a large teaching hospital.

    PubMed Central

    Pegues, D A; Pegues, C F; Hibberd, P L; Ford, D S; Hooper, D C

    1997-01-01

    We prospectively identified patients at the Massachusetts General Hospital from whom vancomycin-resistant enterococci (VRE) were isolated from a clinical specimen from 1 January 1991 through 31 December 1995. VRE strains were available from 139 (82%) of the 169 patients with clinical cases. Of these, 39 (28%) were identical or closely related by pulsed-field gel electrophoresis (i.e., VRE type A strain), including 38 (43%) of 89 VRE strains in 1995. By multivariate analysis, acquisition of the VRE type A strain was associated with receipt of clindamycin (odds ratio [OR] = 10.5), 15 or more days of hospitalization before the first isolation of VRE (OR = 2.9), and residence on one of the general medical floors (OR = 7.8). The VRE type A strain was a vanA strain of Enterococcus faecium and was highly resistant to all antimicrobial agents tested except chloramphenicol. These findings document the rapid dissemination of a highly resistant strain of E. faecium among patients and among other extant VRE strains at the Massachusetts General Hospital in 1995. PMID:9163483

  13. Large-scale whole genome sequencing identifies country-wide spread of an emerging G9P[8] rotavirus strain in Hungary, 2012.

    PubMed

    Dóró, Renáta; Mihalov-Kovács, Eszter; Marton, Szilvia; László, Brigitta; Deák, Judit; Jakab, Ferenc; Juhász, Ágnes; Kisfali, Péter; Martella, Vito; Melegh, Béla; Molnár, Péter; Sántha, Ildikó; Schneider, Ferenc; Bányai, Krisztián

    2014-12-01

    With the availability of rotavirus vaccines routine strain surveillance has been launched or continued in many countries worldwide. In this study relevant information is provided from Hungary in order to extend knowledge about circulating rotavirus strains. Direct sequencing of the RT-PCR products obtained by VP7 and VP4 genes specific primer sets was utilized as routine laboratory method. In addition we explored the advantage of random primed RT-PCR and semiconductor sequencing of the whole genome of selected strains. During the study year, 2012, we identified an increase in the prevalence of G9P[8] strains across the country. This genotype combination predominated in seven out of nine study sites (detection rates, 45-83%). In addition to G9P[8]s, epidemiologically major strains included genotypes G1P[8] (34.2%), G2P[4] (13.5%), and G4P[8] (7.4%), whereas unusual and rare strains were G3P[8] (1%), G2P[8] (0.5%), G1P[4] (0.2%), G3P[4] (0.2%), and G3P[9] (0.2%). Whole genome analysis of 125 Hungarian human rotaviruses identified nine major genotype constellations and uncovered both intra- and intergenogroup reassortment events in circulating strains. Intergenogroup reassortment resulted in several unusual genotype constellations, including mono-reassortant G1P[8] and G9P[8] strains whose genotype 1 (Wa-like) backbone gene constellations contained DS1-like NSP2 and VP3 genes, respectively, as well as, a putative bovine-feline G3P[9] reassortant strain. The conserved genomic constellations of epidemiologically major genotypes suggested the clonal spread of the re-emerging G9P[8] genotype and several co-circulating strains (e.g., G1P[8] and G2P[4]) in many study sites during 2012. Of interest, medically important G2P[4] strains carried bovine-like VP1 and VP6 genes in their genotype constellation. No evidence for vaccine associated selection, or, interaction between wild-type and vaccine strains was obtained. In conclusion, this study reports the reemergence of G9P[8

  14. Bulk Metallic Glass in Supercooled Liquid State

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Deng, L.; Tang, N.; Jin, J. S.

    2014-07-01

    Size effect on the flow behavior of Zr55Al10Ni5Cu30 bulk metallic glass in its supercooled liquid state was investigated by compression tests with specimen diameters varying from 1 to 3 mm. It was found that the smaller the specimen, the higher flow stress exhibits. Strain gradient theory considering friction effect is validated to be suitable to rationalize this size effect. The more geometrical-necessary flow sites needed to be created in smaller specimens, the higher stress it may result in. Considering the efficiency of power dissipation and instability condition, processing maps of different specimens were constructed. With the specimen size decreasing, the processing condition corresponding to low temperature or high strain rate becomes disadvantageous to the thermoplastic forming of Zr55Al10Ni5Cu30, which is closely related to the local stress concentration and strain gradient induced by friction.

  15. Recent TB transmission, clustering and predictors of large clusters in London, 2010–2012: results from first 3 years of universal MIRU-VNTR strain typing

    PubMed Central

    Hamblion, Esther L; Le Menach, Arnaud; Anderson, Laura F; Lalor, Maeve K; Brown, Tim; Abubakar, Ibrahim; Anderson, Charlotte; Maguire, Helen; Anderson, Sarah R

    2016-01-01

    Background The incidence of TB has doubled in the last 20 years in London. A better understanding of risk groups for recent transmission is required to effectively target interventions. We investigated the molecular epidemiological characteristics of TB cases to estimate the proportion of cases due to recent transmission, and identify predictors for belonging to a cluster. Methods The study population included all culture-positive TB cases in London residents, notified between January 2010 and December 2012, strain typed using 24-loci multiple interspersed repetitive units-variable number tandem repeats. Multivariable logistic regression analysis was performed to assess the risk factors for clustering using sociodemographic and clinical characteristics of cases and for cluster size based on the characteristics of the first two cases. Results There were 10 147 cases of which 5728 (57%) were culture confirmed and 4790 isolates (84%) were typed. 2194 (46%) were clustered in 570 clusters, and the estimated proportion attributable to recent transmission was 34%. Clustered cases were more likely to be UK born, have pulmonary TB, a previous diagnosis, a history of substance abuse or alcohol abuse and imprisonment, be of white, Indian, black-African or Caribbean ethnicity. The time between notification of the first two cases was more likely to be <90 days in large clusters. Conclusions Up to a third of TB cases in London may be due to recent transmission. Resources should be directed to the timely investigation of clusters involving cases with risk factors, particularly those with a short period between the first two cases, to interrupt onward transmission of TB. PMID:27417280

  16. In vivo colonization of the mouse large intestine and in vitro penetration of intestinal mucus by an avirulent smooth strain of Salmonella typhimurium and its lipopolysaccharide-deficient mutant.

    PubMed Central

    Nevola, J J; Laux, D C; Cohen, P S

    1987-01-01

    The relative abilities of an avirulent Salmonella typhimurium strain with wild-type lipopolysaccharide (LPS) character, SL5319, and a nearly isogenic LPS-deficient mutant, SL5325, to colonize the large intestines of streptomycin-treated CD-1 mice in vivo and to penetrate colonic mucus in vitro were studied. Previously it had been shown that, when fed simultaneously to streptomycin-treated mice (approximately 10(10) CFU each), the S. typhimurium strain with wild-type LPS colonized at 10(8) CFU/g of feces indefinitely, whereas the LPS-deficient mutant dropped within 3 days to a level of only 10(4) CFU/g of feces. In the present investigation, when SL5325 was allowed to colonize for 8 days before feeding mice SL5319 or when it was fed to mice simultaneously with an Escherichia coli strain of human fecal origin (10(10) CFU each), both strains colonized indefinitely at 10(7) CFU/g of feces. Moreover, when the wild-type and LPS-deficient mutant strains were fed to mice simultaneously in low numbers (approximately 10(5) CFU each) the strains survived equally well in the large intestines for 8 days, after which the LPS-deficient mutant was eliminated (less than 10(2) CFU/g of feces), whereas the wild-type colonized at a level of 10(7) CFU/g of feces. In addition although both strains were able to adhere to mucus and epithelial cell preparations in vitro, the wild-type strain was shown to have greater motility and chemotactic activity on CD-1 mouse colonic mucus in vitro and to more rapidly penetrate and form a stable association with immobilized colonic mucosal components in vitro. Based on these data, we suggest that the ability of an S. typhimurium strain to colonize the streptomycin-treated mouse large intestine may, in part, depend on its ability to penetrate deeply into the mucus layer on the intestinal wall and subsequently, through growth, colonize the mucosa. PMID:3316026

  17. Mechanical behavior of a bulk nanostructured iron alloy

    NASA Astrophysics Data System (ADS)

    Carsley, J. E.; Fisher, A.; Milligan, W. W.; Aifantis, E. C.

    1998-09-01

    Bulk, fully dense materials were prepared from Fe-10Cu with grain diameters between 45 nm and 1.7 µm. The materials were prepared by ball milling of powders in a glove box, followed by hot isostatic pressing (hipping) or powder forging. Larger grain sizes were obtained by thermal treatment of the consolidated powders. The bulk materials were relatively clean, with oxygen levels below 1500 wpm and other contaminants less than 0.1 at. pct. The mechanical behavior of these materials was unique. At temperatures from 77 to 470 K, the first and only mechanism of plastic deformation was intense shear banding, which was accompanied by a perfectly plastic stress-strain response (absence of strain hardening). There was a large tension-compression asymmetry in the strength, and the shear bands did not occur on the plane of maximum shear stress or the plane of zero extension. This behavior, while unusual for metals, has been observed in amorphous polymers and metallic glasses. On the other hand, the fine-grained Fe-10Cu materials behaved like coarse-grained iron in some respects, particularly by obeying the Hall-Petch equation with constants reasonably close to those of pure iron and by exhibiting low-temperature mechanical behavior which was very similar to that of steels. Transmission electron microscopy (TEM) studies found highly elongated grains within shear bands, indicating that shear banding occurred by a dislocation-based mechanism, at least at grain sizes above 100 nm. Similarities and differences between the fine-grained Fe-10Cu and metals, polymers, metallic glasses, radiation-damaged metals, and quench-damaged metals are discussed.

  18. Texture formation in bulk iron processed by simple shear

    SciTech Connect

    Gibbs, M.A.; Hartwig, K.T.; Cornwell, L.R.; Goforth, R.E.; Payzant, E.A.

    1998-11-13

    The preferred orientation of grains in iron after conventional deformation by cold rolling or drawing is characterized as sheet or fiber texture respectively. The main texture component in the rolling direction is [110](001). For the case of wire drawing, again, the [110] direction aligns with the wire axis. A novel method of straining materials called equal channel angular extrusion (ECAE), has recently been developed. This new processing method has the capability of introducing large amounts of plastic strain into bulk material in a relatively uniform manner without a reduction in workpiece cross-section. The processing concept is elegant; press a block of solid material through a constant cross-section tunnel composed of two intersecting channels. The purpose of the work reported here is to determine which kinds of texture are developed by three basic schemes of multipass ECAE. The schemes examined include what are termed route A, route B and route C. Route A maintains the same orientation of the shear plane and shear direction relative to the extrusion direction during all extrusions. Route B involves rotating the billet +90{degree} about the extrusion direction before each even numbered extrusion and {minus}90{degree} before each odd numbered extrusion. Route C processing includes an even number of extrusion passes with a +180{degree} or {minus}180{degree} rotation of the workpiece around the extrusion direction before each extrusion. Conventional sheet and fiber textures can be developed in bulk iron by using multipass ECAE processing. A shear texture results after a single extrusion. Multipass extrusions that return structural elements to their original shape after an even number of passes result in a texture that shows characteristics of both shear and the original texture.

  19. Microstructure Evolution of a Ti-Based Bulk Metallic Glass Composite During Deformation

    NASA Astrophysics Data System (ADS)

    Cui, J.; Li, J. S.; Wang, J.; Kou, H. C.

    2015-02-01

    The deformation behavior of Ti50Zr20Nb12Cu5Be13 bulk metallic glass composite at room temperature was investigated by uniaxial compression tests. The results indicate that the composite exhibits excellent compressive properties at ambient temperature with high fracture strength (about 2425 MPa) and outstanding plasticity (about 23%). All the true stress-strain curves of Ti50Zr20Nb12Cu5Be13 display work-hardening effect with the same tendency which decreases with the increase of the strain. The dendrite morphology almost does not change before yielding, and there are only a few shear bands in the bulk metallic glass composite after yielding. More interestingly, the plastic deformation of dendrites can be observed evidently. Before fracture, the plastic deformation of dendrite becomes more severe, and the dendrite is stretched and more shear bands appear in the composite. Combined with the fracture surface, it can be concluded that the large step shape area, plastic dimple fracture, and shear bands are the evidences of an excellent plasticity in Ti50Zr20Nb12Cu5Be13 bulk metallic glass composite.

  20. Performance and applications of quench melt-growth bulk magnets

    NASA Astrophysics Data System (ADS)

    Nariki, S.; Teshima, H.; Morita, M.

    2016-03-01

    This paper describes the progress in quench melt-growth (QMG) bulk magnets, developed by the Nippon Steel & Sumitomo Metal Corporation, which consist of single crystalline RE123 phase and finely dispersed RE211 particles. QMG bulks can trap high magnetic fields. The field-trapping ability of QMG bulks is largely increased with an improvement in its J c and size, promising the realization of various applications such as flywheel energy-storage systems, ship motors, NMR/MRI spectrometers, wind-power generators and so on. Intensive research has revealed that the optimal RE element is different depending on application requirements. Gd-QMG bulk is the most promising material for several high-field engineering applications. The trapped magnetic field of Gd-QMG bulk 60 mm in diameter at 77 K is twice as large as that of Y-QMG bulk with a similar size due to its excellent J c properties. The large Gd-based QMG bulks up to 150 mm in diameter are fabricated by incorporating the RE compositional gradient method. Compact NMR/MRI spectrometers are one of the promising applications of bulk superconductors. Eu-QMG bulks are suitable for NMR magnets. NMR applications require extremely homogeneous magnetic fields. In the Eu-system, the small paramagnetic moment of a Eu ion compared to a Gd ion improves the field homogeneity in the bulk. For the application of current leads, Dy-based QMG is available by utilizing a low thermal conductivity.

  1. Bulk-barrier transistor

    NASA Astrophysics Data System (ADS)

    Mader, H.; Mueller, R.; Beinvogl, W.

    1983-10-01

    Experimental and theoretical results are presented on a bulk-barrier transistor (BBT). In this device the charge-carrier transportation is determined by an energy barrier, which is located inside a semiconductor. The barrier is the result of a space-charge region in a three-layered n-p-n or p-n-p structure with a very thin middle layer. The height of the energy barrier, which is adjustable by technological parameters, can be controlled by an external voltage.

  2. Teaching Advanced SQL Skills: Text Bulk Loading

    ERIC Educational Resources Information Center

    Olsen, David; Hauser, Karina

    2007-01-01

    Studies show that advanced database skills are important for students to be prepared for today's highly competitive job market. A common task for database administrators is to insert a large amount of data into a database. This paper illustrates how an up-to-date, advanced database topic, namely bulk insert, can be incorporated into a database…

  3. Gold based bulk metallic glass

    SciTech Connect

    Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan

    2005-08-08

    Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5 mm in the best glassformer. Au{sub 49}Ag{sub 5.5}Pd{sub 2.3}Cu{sub 26.9}Si{sub 16.3} has a liquidus temperature of 644 K, a glass transition temperature of 401 K, and a supercooled liquid region of 58 K. The Vickers hardness of the alloys in this system is {approx}350 Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry.

  4. Gold based bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan

    2005-08-01

    Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5mm in the best glassformer. Au49Ag5.5Pd2.3Cu26.9Si16.3 has a liquidus temperature of 644K, a glass transition temperature of 401K, and a supercooled liquid region of 58K. The Vickers hardness of the alloys in this system is ˜350Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry.

  5. Generation of Pure Bulk Valley Current in Graphene

    NASA Astrophysics Data System (ADS)

    Jiang, Yongjin; Low, Tony; Chang, Kai; Katsnelson, Mikhail I.; Guinea, Francisco

    2013-01-01

    The generation of valley current is a fundamental goal in graphene valleytronics but no practical ways of its realization are known yet. We propose a workable scheme for the generation of bulk valley current in a graphene mechanical resonator through adiabatic cyclic deformations of the strains and a chemical potential in the suspended region. The accompanied strain gauge fields can break the spatial mirror symmetry of the problem within each of the two inequivalent valleys, leading to a finite valley current due to quantum pumping. An all-electrical measurement configuration is designed to detect the novel state with pure bulk valley currents.

  6. The benefit of fractional derivatives in modelling the dynamics of filler-reinforced rubber under large strains: a comparison with the Maxwell-element approach

    NASA Astrophysics Data System (ADS)

    Wollscheid, D.; Lion, A.

    2014-05-01

    The dynamic properties of rubber-like materials are characterised by a significant dependence on the predeformation and the frequency. The focus of this paper is to represent the frequency and predeformation dependent dynamic behaviour of a carbon-black filled SBR rubber with 40 phr amount of filler using the concept of fractional derivatives. Thus, we introduce a constitutive approach of finite fractional viscoelasticity which is suitable to approximate the dynamic material properties with respect to the storage and the loss modulus. The constitutive approach is based on a proposal of [18] which was modified by a deformation dependent relaxation function in a previous work [46] to represent the dependence of the dynamic modulus on the predeformation and the frequency. The constitutive approach in [46] is based on the classical theory of finite viscoelasticity and formulated in the frequency domain. In this work, the approach of [46] will be extended by the concept of fractional derivatives and compared to the classical one. Thus, the classical and the extended fractional constitutive models are firstly introduced and the complex modulus tensors of both models are derived. It should be mentioned that both constitutive approaches are firstly formulated in the time domain. This formulation is necessary to satisfy the thermodynamical consistency. In order to conduct vibration analyses of elastomer structures with high computational efficiency, the equations are then transferred to the frequency domain. To this end, the constitutive model is geometrically linearised in the neighbourhood of a large and temporally constant predeformation. The incremental strain tensor varies harmonically and its amplitude has to be small. Furthermore, parameter identification of both approaches is done on the basis of quasi-static and dynamic investigations of the carbon-black filled SBR rubber. The numerical results of the parameter identification of the classical and the fractional

  7. Selective 13C labeling of nucleotides for large RNA NMR spectroscopy using an E. coli strain disabled in the TCA cycle.

    PubMed

    Thakur, Chandar S; Sama, Jacob N; Jackson, Melantha E; Chen, Bin; Dayie, T Kwaku

    2010-12-01

    Escherichia coli (E. coli) is an ideal organism to tailor-make labeled nucleotides for biophysical studies of RNA. Recently, we showed that adding labeled formate enhanced the isotopic enrichment at protonated carbon sites in nucleotides. In this paper, we show that growth of a mutant E. coli strain DL323 (lacking succinate and malate dehydrogenases) on (13)C-2-glycerol and (13)C-1,3-glycerol enables selective labeling at many useful sites for RNA NMR spectroscopy. For DL323 E. coli grown in (13)C-2-glycerol without labeled formate, all the ribose carbon atoms are labeled except the C3' and C5' carbon positions. Consequently the C1', C2' and C4' positions remain singlet. In addition, only the pyrimidine base C6 atoms are substantially labeled to ~96% whereas the C2 and C8 atoms of purine are labeled to ~5%. Supplementing the growth media with (13)C-formate increases the labeling at C8 to ~88%, but not C2. Not unexpectedly, addition of exogenous formate is unnecessary for attaining the high enrichment levels of ~88% for the C2 and C8 purine positions in a (13)C-1,3-glycerol based growth. Furthermore, the ribose ring is labeled in all but the C4' carbon position, such that the C2' and C3' positions suffer from multiplet splitting but the C5' position remains singlet and the C1' position shows a small amount of residual C1'-C2' coupling. As expected, all the protonated base atoms, except C6, are labeled to ~90%. In addition, labeling with (13)C-1,3-glycerol affords an isolated methylene ribose with high enrichment at the C5' position (~90%) that makes it particularly attractive for NMR applications involving CH(2)-TROSY modules without the need for decoupling the C4' carbon. To simulate the tumbling of large RNA molecules, perdeuterated glycerol was added to a mixture of the four nucleotides, and the methylene TROSY experiment recorded at various temperatures. Even under conditions of slow tumbling, all the expected carbon correlations were observed, which indicates

  8. Identification of Stable Processing Parameters in Ti-6Al-4V Alloy from a Wide Temperature Range Across β Transus and a Large Strain Rate Range

    NASA Astrophysics Data System (ADS)

    Quan, Guo-Zheng; Wen, Hai-Rong; Pu, Shi-Ao; Zou, Zhen-Yu; Wu, Dong-Sen

    2015-11-01

    The hot workability of Ti-6Al-4V alloy was investigated according to the measured stress-strain data and their derived forms from a series of hot compressions at the temperatures of 1,023-1,323 K and strain rates of 0.01-10 s-1 with a height reduction of 60%. As the true strain was 0.3, 0.5, 0.7 and 0.9, respectively, the response maps of strain rate sensitivity (m-value), power dissipation efficiency (η-value) and instability parameter (ξ-value) to temperature and strain rate were developed on the basis of dynamic material model (DMM). Then the processing map was obtained by superimposition of the power dissipation and the instability maps. According to the processing map, the stable regions (η > 0 and ξ > 0) and unstable regions (η < 0 or ξ < 0) were clarified clearly. Further, the stable regions (temperatures of 1,198-1,248 K and strain rates of 0.01-0.1 s-1) with higher η value (> 0.3) corresponding to the ideal deformation mechanisms involving globularization and superplasticity were identified and recommended. The microstructures of the deformed samples were then observed by microscopy. And homogeneous microstructures with refined grains were found in the recommended parameter domains. The optimal working parameter domains identified by processing map and validated by microstructure observations contribute to the design in reasonable hot forming process of Ti-6Al-4V alloy without resorting to expensive and time-consuming trial-and-error methods.

  9. 'Work-Hardenable' Ductile Bulk Metallic Glass

    SciTech Connect

    Das, Jayanta; Eckert, Juergen; Tang Meibo; Wang Weihua; Kim, Ki Buem; Baier, Falko; Theissmann, Ralf

    2005-05-27

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive 'work hardening' and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The 'work-hardening' capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  10. Bulk material handling system

    DOEpatents

    Kleysteuber, William K.; Mayercheck, William D.

    1979-01-01

    This disclosure relates to a bulk material handling system particularly adapted for underground mining and includes a monorail supported overhead and carrying a plurality of conveyors each having input and output end portions with the output end portion of a first of the conveyors positioned above an input end portion of a second of the conveyors, a device for imparting motion to the conveyors to move the material from the input end portions toward the output end portions thereof, a device for supporting at least one of the input and output end portions of the first and second conveyors from the monorail, and the supporting device including a plurality of trolleys rollingly supported by the monorail whereby the conveyors can be readily moved therealong.

  11. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  12. Bulk muscles, loose cables.

    PubMed

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-01-01

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558

  13. Creating bulk nanocrystalline metal.

    SciTech Connect

    Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  14. Explosive bulk charge

    DOEpatents

    Miller, Jacob Lee

    2015-04-21

    An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.

  15. 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.

  16. Epitaxial strain effects on layered polar oxides from first-principles

    NASA Astrophysics Data System (ADS)

    Lu, Xuezeng; Rondinelli, James; Materials Theory; Design Group Team

    Epitaxial strain is a powerful tool to generate ferroelectric phases in thin films owing to polarization-strain coupling. The coupling of the oxygen rotations to strain can also be exploited to realize oxygen rotation-sensitive properties such as metal-insulator transitions and magnetic reconstructions. Here, we use electronic structure calculations to investigate the effects of biaxial strain on (001) thin films of the hybrid-improper ferroelectric Ca3Ti2O7. Besides the bulk Cmc21 phase, we also find a new phase emerges under both experimentally accessible biaxial compressive and tensile strains. Furthermore, a large change in the dielectric anisotropy of the film is found at the tensile phase boundary, which we propose could be electric field tunable. Our results may offer a route to search for new functionalities in layered-perovskite oxides.

  17. Atomic-level study of BiFe O3 under epitaxial strain

    NASA Astrophysics Data System (ADS)

    Graf, M.; Sepliarsky, M.; Stachiotti, M. G.

    2016-08-01

    Structural and thermal properties of BiFe O3 under compressive epitaxial strain are investigated using a shell model fitted to first-principles calculations. We show that a model developed for the bulk describes properly the behavior of the compound as function of the strain, including the appearance of tetragonallike phase with a large c /a ratio. The obtained temperature-strain phase diagram reproduces several features observed experimentally in thin films. Molecular dynamic simulations show that morphotropic phase boundary separating the R -like and T -like regions is temperature independent but with different phases along the transition region. The microscopic analysis of the temperature-strain phase diagram emphasizes the relevance of the interplay between polarization, oxygen octahedron rotations, and strain.

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

    SciTech Connect

    Thorbeck, Ted; Zimmerman, Neil M.

    2015-08-15

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

  19. 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.

  20. Swept optical SSB-SC modulation technique for high-resolution large-dynamic-range static strain measurement using FBG-FP sensors.

    PubMed

    Huang, Wenzhu; Zhang, Wentao; Li, Fang

    2015-04-01

    This Letter presents a static strain demodulation technique for FBG-FP sensors using a suppressed carrier LiNbO(3) (LN) optical single sideband (SSB-SC) modulator. A narrow-linewidth tunable laser source is generated by driving the modulator using a linear chirp signal. Then this tunable single-frequency laser is used to interrogate the FBG-FP sensors with the Pound-Drever-Hall (PDH) technique, which is beneficial to eliminate the influence of light intensity fluctuation of the modulator at different tuning frequencies. The static strain is demodulated by calculating the wavelength difference of the PDH signals between the sensing FBG-FP sensor and the reference FBG-FP sensor. As an experimental result using the modulator, the linearity (R2) of the time-frequency response increases from 0.989 to 0.997, and the frequency-swept range (dynamic range) increases from hundreds of MHz to several GHz compared with commercial PZT-tunable lasers. The high-linearity time-wavelength relationship of the modulator is beneficial for improving the strain measurement resolution, as it can solve the problem of the frequency-swept nonlinearity effectively. In the laboratory test, a 0.67 nanostrain static strain resolution, with a 6 GHz dynamic range, is demonstrated. PMID:25831344

  1. Detection of a large RIII-derived chromosomal segment on chromosome 10 in the H-2 congenic strain B10.RIII(71NS)/Sn

    SciTech Connect

    Dong, P.; Hood, L.; McIndoe, R.A.

    1996-01-15

    This report describes the results of a study of the chromosomal localization of certain loci related to the susceptibility of specific mouse strains to collagen-induced arthritis, the biological model for rheumatoid arthritis. There were surprising results concerning the chromosomal mapping of mouse chromosome 10 and 17 and the backcrosses of mice involved. 7 refs., 1 fig., 2 tabs.

  2. Effects of gasket on coupled plastic flow and strain-induced phase transformations under high pressure and large torsion in a rotational diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Feng, Biao; Levitas, Valery I.

    2016-01-01

    Combined plastic flow and strain-induced phase transformations (PTs) under high pressure in a sample within a gasket subjected to three dimensional compression and torsion in a rotational diamond anvil cell (RDAC) are studied using a finite element approach. The results are obtained for the weaker, equal-strength, and stronger high-pressure phases in comparison with low-pressure phases. It is found that, due to the strong gasket, the pressure in the sample is relatively homogenous and the geometry of the transformed zones is mostly determined by heterogeneity in plastic flow. For the equal-strength phases, the PT rate is higher than for the weaker and stronger high-pressure phases. For the weaker high-pressure phase, transformation softening induces material instability and leads to strain and PT localization. For the stronger high-pressure phase, the PT is suppressed by strain hardening during PT. The effect of the kinetic parameter k that scales the PT rate in the strain-controlled kinetic equation is also examined. In comparison with a traditional diamond anvil cell without torsion, the PT progress is much faster in RDAC under the same maximum pressure in the sample. Finally, the gasket size and strength effects are discussed. For a shorter and weaker gasket, faster plastic flow in radial and thickness directions leads to faster PT kinetics in comparison with a longer and stronger gasket. The rates of PT and plastic flows are not very sensitive to the modest change in a gasket thickness. Multiple experimental results are reproduced and interpreted. Obtained results allow one to design the desired pressure-plastic strain loading program in the experiments for searching new phases, reducing PT pressure by plastic shear, extracting kinetic properties from experiments with heterogeneous fields, and controlling homogeneity of all fields and kinetics of PTs.

  3. 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.

  4. Robust large-gap quantum spin Hall insulators in chemically decorated arsenene films

    NASA Astrophysics Data System (ADS)

    Wang, Dongchao; Chen, Li; Shi, Changmin; Wang, Xiaoli; Cui, Guangliang; Zhang, Pinhua; Chen, Yeqing

    2016-03-01

    Based on first-principles calculations, we propose one new category of two-dimensional topological insulators (2D TIs) in chemically functionalized (-CH3 and -OH) arsenene films. The results show that the surface decorated arsenene (AsCH3 and AsOH) films are intrinsic 2D TIs with sizeable bulk gap. The bulk energy gaps are 0.184 eV, and 0.304 eV in AsCH3 and AsOH films, respectively. Such large bulk gaps make them suitable to realize quantum spin Hall effect in an experimentally accessible temperature regime. Topologically helical edge states in these systems are desirable for dissipationless transport. Moreover, we find that the topological properties in these systems are robust against mechanical deformation by exerting biaxial strain. These novel 2D TIs with large bulk gaps are potential candidate in future electronic devices with ultralow dissipation.

  5. Effect of constitutive equations on qualitative behavior of solutions in the vicinity of bi-material interfaces at large plastic strains

    NASA Astrophysics Data System (ADS)

    Alexandrov, Sergei; Goldstein, Robert

    2016-04-01

    The main objective of the present paper is to compare, by means of a problem permitting a closed-form solution, qualitative behavior of solutions based on three models of strain hardening plasticity and two models of viscoplasticity. The elastic portion of the strain tensor is neglected. The study focuses on the solution behavior near frictional interfaces. The solution behavior essentially depends on the model chosen. Such features of the solutions as nonexistence and singularity are emphasized. The key constitutive parameter that divides all the models considered into two groups is the saturation stress. In particular, under certain conditions no solution satisfying the regime of sticking exists for the models that involve the saturation stress. Qualitative comparison with numerous experimental observations is made. It is concluded that models with a saturation stress, including the models considered in the present paper, may be capable of describing the generation of a narrow layer of severe plastic deformation in the vicinity of frictional interfaces.

  6. Large magnetic entropy change and adiabatic temperature rise of a Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} bulk metallic glass

    SciTech Connect

    Xia, L.; Tang, M. B.; Chan, K. C.; Dong, Y. D.

    2014-06-14

    Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} bulk metallic glass (BMG) was synthesized by minor Ni substitution for Co in the Gd{sub 55}Al{sub 20}Co{sub 25} BMG in which excellent glass forming ability (GFA) and magneto-caloric effect were reported previously. The Gd{sub 55}Al{sub 20}Ni{sub 20}Co{sub 5} amorphous rod has a similar GFA to the Gd{sub 55}Al{sub 20}Co{sub 25} BMG but exhibits better magnetic properties. The peak value of magnetic entropy change (−ΔS{sub m}{sup peak}) of the Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} BMG is 9.8 Jkg{sup −1} K{sup −1}. The field dependence of −ΔS{sub m}{sup peak} follows a −ΔS{sub m}{sup peak}∝H{sup 0.85} relationship. The adiabatic temperature rise of the rod is 4.74 K under 5 T and is larger than of other BMGs previously reported. The improved magnetic properties were supposed to be induced by the enhanced interaction between 4f electron in the rare-earth and 3d electron in the transition metal elements by means of a minor Ni substitution for Co.

  7. 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.

  8. Gravitational potential wells and the cosmic bulk flow

    NASA Astrophysics Data System (ADS)

    Wang, Yuyu; Kumar, Abhinav; Feldman, Hume; Watkins, Richard

    2016-03-01

    The bulk flow is a volume average of the peculiar velocities and a useful probe of the mass distribution on large scales. The gravitational instability model views the bulk flow as a potential flow that obeys a Maxwellian Distribution. We use two N-body simulations, the LasDamas Carmen and the Horizon Run, to calculate the bulk flows of various sized volumes in the simulation boxes. Once we have the bulk flow velocities as a function of scale, we investigate the mass and gravitational potential distribution around the volume. We found that matter densities can be asymmetrical and difficult to detect in real surveys, however, the gravitational potential and its gradient may provide better tools to investigate the underlying matter distribution. This study shows that bulk flows are indeed potential flows and thus provides information on the flow sources. We also show that bulk flow magnitudes follow a Maxwellian distribution on scales > 10h-1 Mpc.

  9. Tensile strains give rise to strong size effects for thermal conductivities of silicene, germanene and stanene

    NASA Astrophysics Data System (ADS)

    Kuang, Y. D.; Lindsay, L.; Shi, S. Q.; Zheng, G. P.

    2016-02-01

    Based on first principles calculations and self-consistent solution of the linearized Boltzmann-Peierls equation for phonon transport approach within a three-phonon scattering framework, we characterize lattice thermal conductivities k of freestanding silicene, germanene and stanene under different isotropic tensile strains and temperatures. We find a strong size dependence of k for silicene with tensile strain, i.e., divergent k with increasing system size; however, the intrinsic room temperature k for unstrained silicene converges with system size to 19.34 W m-1 K-1 at 178 nm. The room temperature k of strained silicene becomes as large as that of bulk silicon at 84 μm, indicating the possibility of using strain in silicene to manipulate k for thermal management. The relative contribution to the intrinsic k from out-of-plane acoustic modes is largest for unstrained silicene, ~39% at room temperature. The single mode relaxation time approximation, which works reasonably well for bulk silicon, fails to appropriately describe phonon thermal transport in silicene, germanene and stanene within the temperature range considered. For large samples of silicene, k increases with tensile strain, peaks at ~7% strain and then decreases with further strain. In germanene and stanene, increasing strain hardens and stabilizes long wavelength out-of-plane acoustic phonons, and leads to similar k behaviors to those of silicene. These findings further our understanding of phonon dynamics in group-IV buckled monolayers and may guide transfer and fabrication techniques for these freestanding samples and engineering of k by size and strain for applications of thermal management and thermoelectricity.Based on first principles calculations and self-consistent solution of the linearized Boltzmann-Peierls equation for phonon transport approach within a three-phonon scattering framework, we characterize lattice thermal conductivities k of freestanding silicene, germanene and stanene under

  10. 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.

  11. Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons.

    PubMed

    Yan, Yuan; Zhou, Xu; Jin, Han; Li, Cai-Zhen; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Liu, Kaihui; Yu, Dapeng; Dressel, Martin; Liao, Zhi-Min

    2015-10-27

    Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi2Se3 bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi2Se3 nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi2Se3 nanoribbons grown along the ⟨112̅0⟩ direction. The frequencies of the in-plane Eg(2) and out-of-plane A1g(1) modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the ⟨112̅0⟩ direction with the curved {0001} surface. In this case, the phonon deformation potential of the Eg(2) phonon for 100 nm-thick Bi2Se3 nanoribbon is up to 0.94 cm(–1)/%, which is twice of that in Bi2Se3 bulk material (0.52 cm(–1)/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures. PMID:26365014

  12. Tensile strains give rise to strong size effects for thermal conductivities of silicene, germanene and stanene

    DOE PAGESBeta

    Kuang, Youdi D.; Lindsay, Lucas R.; Shi, Sanqiang Q.; Zhen, Guangping P.

    2016-01-11

    Based on first principles calculations and self-consistent solution of linearized Boltzmann-Peierls equation for phonon transport approach within a three-phonon scattering framework, we characterize lattice thermal conductivities k of freestanding silicene, germanene and stanene under different isotropic tensile strains and temperatures. We find a strong size dependence of k for silicene with tensile strain, i.e., divergent k with increasing system size, in contrast, the intrinsic room temperature k for unstrained silicene converges with system size to 19.34 W/m–1 K–1 by 178 nm. The room temperature k of strained silicene becomes as large as that of bulk silicon by 84 m, indicatingmore » the possibility of using strain in silicene to manipulate k for thermal management. The relative contribution to the intrinsic k from out-of-plane acoustic modes is largest for unstrained silicene, –39% at room temperature. The single mode relaxation time approximation, which works reasonably well for bulk silicon, fails to appropriately describe phonon thermal transport in silicene, germanene and stanene within the temperature range considered. For large samples of silicene, k increases with tensile strain, peaks at –7% strain and then decreases with further strain. In germanene and stanene increasing strain hardens and stabilizes long wavelength out-of-plane acoustic phonons, and leads to similar k behaviors to those of silicene. As a result, these findings further our understanding of phonon dynamics in group-IV buckled monolayers and may guide transfer and fabrication techniques of these freestanding samples and engineering k by size and strain for applications of thermal management and thermoelectricity.« less

  13. Tensile strains give rise to strong size effects for thermal conductivities of silicene, germanene and stanene.

    PubMed

    Kuang, Y D; Lindsay, L; Shi, S Q; Zheng, G P

    2016-02-14

    Based on first principles calculations and self-consistent solution of the linearized Boltzmann-Peierls equation for phonon transport approach within a three-phonon scattering framework, we characterize lattice thermal conductivities k of freestanding silicene, germanene and stanene under different isotropic tensile strains and temperatures. We find a strong size dependence of k for silicene with tensile strain, i.e., divergent k with increasing system size; however, the intrinsic room temperature k for unstrained silicene converges with system size to 19.34 W m(-1) K(-1) at 178 nm. The room temperature k of strained silicene becomes as large as that of bulk silicon at 84 μm, indicating the possibility of using strain in silicene to manipulate k for thermal management. The relative contribution to the intrinsic k from out-of-plane acoustic modes is largest for unstrained silicene, ∼39% at room temperature. The single mode relaxation time approximation, which works reasonably well for bulk silicon, fails to appropriately describe phonon thermal transport in silicene, germanene and stanene within the temperature range considered. For large samples of silicene, k increases with tensile strain, peaks at ∼7% strain and then decreases with further strain. In germanene and stanene, increasing strain hardens and stabilizes long wavelength out-of-plane acoustic phonons, and leads to similar k behaviors to those of silicene. These findings further our understanding of phonon dynamics in group-IV buckled monolayers and may guide transfer and fabrication techniques for these freestanding samples and engineering of k by size and strain for applications of thermal management and thermoelectricity. PMID:26815838

  14. Characteristics of an electromagnetic levitation system using a bulk superconductor

    SciTech Connect

    Senba, A.; Kitahara, H.; Ohsaki, H.; Masada, E.

    1996-09-01

    It is beneficial to apply a high-Tc bulk superconductor as a large flux source to an electromagnetic levitation system, which needs large amounts of levitation force. The authors made an attractive-type electromagnetic levitation system using a hybrid magnet that mainly consisted of bulk superconductor and control coils to confirm the principle of the levitation, and obtained characteristics of its system by both experiment and numerical analysis with magnetic circuit calculation. This is applicable to maglev transportation systems.

  15. Crystal structure and electronic properties of bulk and thin film brownmillerite oxides.

    SciTech Connect

    Young, Joshua; Rondinelli, James M.

    2015-11-17

    The equilibrium structure and functional properties exhibited by brownmillerite oxides, a family of perovskitederived structures with alternating layers of BO6 octahedra and BO4 tetrahedra, viz., ordered arrangements of oxygen vacancies, is dependent on a variety of competing crystal-chemistry factors. We use electronic structure calculations to disentangle the complex interactions in two ferrates, Sr2Fe2O5 and Ca2Fe2O5, relating the stability of the equilibrium (strain-free) and thin film structures to both previously identified and herein newly proposed descriptors.We show that cation size and intralayer separation of the tetrahedral chains provide key contributions to the preferred ground state. We show the bulk ground-state structure is retained in the ferrates over a range of strain values; however, a change in the orientation of the tetrahedral chains, i.e., a perpendicular orientation of the vacancies relative to the substrate, is stabilized in the compressive region. The structure stability under strain is largely governed by maximizing the intraplane separation of the dipoles generated from rotations of the FeO4 tetrahedra. Lastly, we find that the electronic band gap is strongly influenced by strain, manifesting as an unanticipated asymmetric-vacancy alignment dependent response. This atomistic understanding establishes a practical route for the design of functional electronic materials in thin film geometries.

  16. Crystal structure and electronic properties of bulk and thin film brownmillerite oxides

    NASA Astrophysics Data System (ADS)

    Young, Joshua; Rondinelli, James M.

    2015-11-01

    The equilibrium structure and functional properties exhibited by brownmillerite oxides, a family of perovskite-derived structures with alternating layers of B O6 octahedra and B O4 tetrahedra, viz., ordered arrangements of oxygen vacancies, is dependent on a variety of competing crystal-chemistry factors. We use electronic structure calculations to disentangle the complex interactions in two ferrates, Sr2Fe2O5 and Ca2Fe2O5 , relating the stability of the equilibrium (strain-free) and thin film structures to both previously identified and herein newly proposed descriptors. We show that cation size and intralayer separation of the tetrahedral chains provide key contributions to the preferred ground state. We show the bulk ground-state structure is retained in the ferrates over a range of strain values; however, a change in the orientation of the tetrahedral chains, i.e., a perpendicular orientation of the vacancies relative to the substrate, is stabilized in the compressive region. The structure stability under strain is largely governed by maximizing the intraplane separation of the dipoles generated from rotations of the FeO4 tetrahedra. Lastly, we find that the electronic band gap is strongly influenced by strain, manifesting as an unanticipated asymmetric-vacancy alignment dependent response. This atomistic understanding establishes a practical route for the design of functional electronic materials in thin film geometries.

  17. Strain-induced quantum spin Hall effect in methyl-substituted germanane GeCH3

    PubMed Central

    Ma, Yandong; Dai, Ying; Wei, Wei; Huang, Baibiao; Whangbo, Myung-Hwan

    2014-01-01

    Quantum spin Hall (QSH) insulators exhibit a bulk insulting gap and metallic edge states characterized by nontrivial topology. We investigated the electronic structure of an isolated layer of methyl substituted germanane GeCH3 by density functional calculations (DFT), and its dynamic stability by phonon dispersion calculations. Our results show that an isolated GeCH3 layer has no dynamic instability, and is a QSH insulator under reasonable strain. This QSH insulator has a large enough band gap (up to 108 meV) at 12% strain. The advantageous features of this QSH insulator for practical room-temperature applications are discussed. PMID:25465887

  18. Reversible piezomagnetoelectric switching in bulk polycrystalline ceramics

    SciTech Connect

    Stevenson, T. Bennett, J.; Brown, A. P.; Wines, T.; Bell, A. J.; Comyn, T. P.; Smith, R. I.

    2014-08-01

    Magnetoelectric (ME) coupling in materials offer tremendous advantages in device functionality enabling technologies including advanced electronic memory, combining electronic speed, and efficiency with magnetic robustness. However, low cost polycrystalline ME materials are excluded from most commercial applications, operating only at cryogenic temperatures, impractically large electric/magnetic fields, or with low ME coefficients (1-100 mV/cm Oe). Despite this, the technological potential of single compound ME coupling has continued to drive research into multiferroics over the last two decades. Here we show that by manipulating the large induced atomic strain within the polycrystalline, room temperature multiferroic compound 0.7BiFeO{sub 3}–0.3PbTiO{sub 3}, we can induce a reversible, piezoelectric strain controlled ME effect. Employing an in situ neutron diffraction experiment, we have demonstrated that this piezomagnetoelectric effect manifests with an applied electric field >8 kV/mm at the onset of piezoelectric strain, engineered in to the compound by crystallographic phase mixing. This produces a remarkable intrinsic ME coefficient of 1276 mV/cm Oe, due to a strain driven modification to the oxygen sub-lattice, inducing an increase in magnetic moment per Fe{sup 3+} ion of +0.142 μ{sub B}. This work provides a framework for investigations into strain engineered nanostructures to realize low-cost ME devices designed from the atoms up, as well as contributing to the deeper understanding of single phase ME coupling mechanisms.

  19. Advanced bulk processing of lightweight materials for utilization in the transportation sector

    NASA Astrophysics Data System (ADS)

    Milner, Justin L.

    The overall objective of this research is to develop the microstructure of metallic lightweight materials via multiple advanced processing techniques with potentials for industrial utilization on a large scale to meet the demands of the aerospace and automotive sectors. This work focused on (i) refining the grain structure to increase the strength, (ii) controlling the texture to increase formability and (iii) directly reducing processing/production cost of lightweight material components. Advanced processing is conducted on a bulk scale by several severe plastic deformation techniques including: accumulative roll bonding, isolated shear rolling and friction stir processing to achieve the multiple targets of this research. Development and validation of the processing techniques is achieved through wide-ranging experiments along with detailed mechanical and microstructural examination of the processed material. On a broad level, this research will make advancements in processing of bulk lightweight materials facilitating industrial-scale implementation. Where accumulative roll bonding and isolated shear rolling, currently feasible on an industrial scale, processes bulk sheet materials capable of replacing more expensive grades of alloys and enabling low-temperature and high-strain-rate formability. Furthermore, friction stir processing to manufacture lightweight tubes, made from magnesium alloys, has the potential to increase the utilization of these materials in the automotive and aerospace sectors for high strength - high formability applications. With the increased utilization of these advanced processing techniques will significantly reduce the cost associated with lightweight materials for many applications in the transportation sectors.

  20. Improving Bulk Microphysics Parameterizations in Simulations of Aerosol Effects

    SciTech Connect

    Wang, Yuan; Fan, Jiwen; Zhang, Renyi; Leung, Lai-Yung R.; Franklin, Charmaine N.

    2013-06-05

    To improve the microphysical parameterizations for simulations of the aerosol indirect effect (AIE) in regional and global climate models, a double-moment bulk microphysical scheme presently implemented in the Weather Research and Forecasting (WRF) model is modified and the results are compared against atmospheric observations and simulations produced by a spectral bin microphysical scheme (SBM). Rather than using prescribed aerosols as in the original bulk scheme (Bulk-OR), a prognostic doublemoment aerosol representation is introduced to predict both the aerosol number concentration and mass mixing ratio (Bulk-2M). The impacts of the parameterizations of diffusional growth and autoconversion and the selection of the embryonic raindrop radius on the performance of the bulk microphysical scheme are also evaluated. Sensitivity modeling experiments are performed for two distinct cloud regimes, maritime warm stratocumulus clouds (SC) over southeast Pacific Ocean from the VOCALS project and continental deep convective clouds (DCC) in the southeast of China from the Department of Energy/ARM Mobile Facility (DOE/AMF) - China field campaign. The results from Bulk-2M exhibit a much better agreement in the cloud number concentration and effective droplet radius in both the SC and DCC cases with those from SBM and field measurements than those from Bulk-OR. In the SC case particularly, Bulk-2M reproduces the observed drizzle precipitation, which is largely inhibited in Bulk-OR. Bulk-2M predicts enhanced precipitation and invigorated convection with increased aerosol loading in the DCC case, consistent with the SBM simulation, while Bulk-OR predicts the opposite behaviors. Sensitivity experiments using four different types of autoconversion schemes reveal that the autoconversion parameterization is crucial in determining the raindrop number, mass concentration, and drizzle formation for warm 2 stratocumulus clouds. An embryonic raindrop size of 40 μm is determined as a more

  1. Dynamic measurement of bulk modulus

    NASA Technical Reports Server (NTRS)

    Dowler, W. L.; Strand, L. D.

    1979-01-01

    Technique based on measuring phase difference between microwave reference and test signals and has been used to determine change in bulk modulus of solid-fuel rocket propellants should be useful in studying other dielectric materials.

  2. Induction detection of concealed bulk banknotes

    NASA Astrophysics Data System (ADS)

    Fuller, Christopher; Chen, Antao

    2011-10-01

    Bulk cash smuggling is a serious issue that has grown in volume in recent years. By building on the magnetic characteristics of paper currency, induction sensing is found to be capable of quickly detecting large masses of banknotes. The results show that this method is effective in detecting bulk cash through concealing materials such as plastics, cardboards, fabrics and aluminum foil. The significant difference in the observed phase between the received signals caused by conducting materials and ferrite compounds, found in banknotes, provides a good indication that this process can overcome the interference by metal objects in a real sensing application. This identification strategy has the potential to not only detect the presence of banknotes, but also the number, while still eliminating false positives caused by metal objects.

  3. Modeling direct interband tunneling. I. Bulk semiconductors

    SciTech Connect

    Pan, Andrew; Chui, Chi On

    2014-08-07

    Interband tunneling is frequently studied using the semiclassical Kane model, despite uncertainty about its validity. Revisiting the physical basis of this formula, we find that it neglects coupling to other bands and underestimates transverse tunneling. As a result, significant errors can arise at low and high fields for small and large gap materials, respectively. We derive a simple multiband tunneling model to correct these defects analytically without arbitrary parameters. Through extensive comparison with band structure and quantum transport calculations for bulk InGaAs, InAs, and InSb, we probe the accuracy of the Kane and multiband formulas and establish the superiority of the latter. We also show that the nonlocal average electric field should be used when applying either of these models to nonuniform potentials. Our findings are important for efficient analysis and simulation of bulk semiconductor devices involving tunneling.

  4. Effective pure states for bulk quantum computation

    SciTech Connect

    Knill, E.; Chuang, I.; Laflamme, R.

    1997-11-01

    In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) and Corey et al. (spatial averaging) for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla qubits and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high temperature and low temperature bulk quantum computing and analyze the signal to noise behavior of each.

  5. The Soret effect in bulk metallic glasses

    SciTech Connect

    Liu, Yong; Liu, Chain T; George, Easo P; Wang, Xianzhen

    2007-01-01

    Compositional inhomogeneity induced by the Soret effect was studied in two Zr-based bulk metallic glasses (BMG): Zr50Cu50 and Zr50Cu40Al10 (at.%), and one Cu-based BMG: Cu60Zr30Ti10 (at.%), all of which were prepared by rapid solidification. The concentration of Cu increases from the surface to the interior, while the concentrations of Zr, Ti and Al decrease. The magnitude of the Soret effect is found to be highly dependant on sample size and interactions between the diffusing atoms in bulk metallic glasses. For the Zr50Cu50 alloy, a large sample size favors the Soret effect, because of the longer diffusion time it affords compared to a small sample. Further, the additions of Al and Ti in the Zr-Cu BMGs reduce the magnitude of the Soret effect by the formation of short-range order and/or inter-atomic clusters.

  6. Induction detection of concealed bulk banknotes

    NASA Astrophysics Data System (ADS)

    Fuller, Christopher; Chen, Antao

    2012-06-01

    The smuggling of bulk cash across borders is a serious issue that has increased in recent years. In an effort to curb the illegal transport of large numbers of paper bills, a detection scheme has been developed, based on the magnetic characteristics of bank notes. The results show that volumes of paper currency can be detected through common concealing materials such as plastics, cardboard, and fabrics making it a possible potential addition to border security methods. The detection scheme holds the potential of also reducing or eliminating false positives caused by metallic materials found in the vicinity, by observing the stark difference in received signals caused by metal and currency. The detection scheme holds the potential to detect for both the presence and number of concealed bulk notes, while maintaining the ability to reduce false positives caused by metal objects.

  7. Segregation stabilizes nanocrystalline bulk steel with near theoretical strength.

    PubMed

    Li, Yujiao; Raabe, Dierk; Herbig, Michael; Choi, Pyuck-Pa; Goto, Shoji; Kostka, Aleksander; Yarita, Hiroshi; Borchers, Christine; Kirchheim, Reiner

    2014-09-01

    Grain refinement through severe plastic deformation enables synthesis of ultrahigh-strength nanostructured materials. Two challenges exist in that context: First, deformation-driven grain refinement is limited by dynamic dislocation recovery and crystal coarsening due to capillary driving forces; second, grain boundary sliding and hence softening occur when the grain size approaches several nanometers. Here, both challenges have been overcome by severe drawing of a pearlitic steel wire (pearlite: lamellar structure of alternating iron and iron carbide layers). First, at large strains the carbide phase dissolves via mechanical alloying, rendering the initially two-phase pearlite structure into a carbon-supersaturated iron phase. This carbon-rich iron phase evolves into a columnar nanoscaled subgrain structure which topologically prevents grain boundary sliding. Second, Gibbs segregation of the supersaturated carbon to the iron subgrain boundaries reduces their interface energy, hence reducing the driving force for dynamic recovery and crystal coarsening. Thus, a stable cross-sectional subgrain size <10  nm is achieved. These two effects lead to a stable columnar nanosized grain structure that impedes dislocation motion and enables an extreme tensile strength of 7 GPa, making this alloy the strongest ductile bulk material known. PMID:25238372

  8. 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.

  9. Recent Progress in HTS Bulk Technology and Performance at NSC

    NASA Astrophysics Data System (ADS)

    Teshima, Hidekazu; Morita, Mitsuru

    This paper describes the current status of large single-grained RE-Ba-Cu-O (where RE: Y or rare earth elements) bulk superconductors with excellent superconducting properties in Nippon Steel Corporation. Intensive research on RE-Ba-Cu-O revealed that the optimal RE element is different for application requirements. While Gd-Ba-Cu-O bulk superconductors are greatly attractive for almost all bulk applications, Eu-Ba-Cu-O is suitable for compact NMR/MRI and Dy-Ba-Cu-O for current leads. In addition, single-domain bulk superconductors have been grown up to 150 mm in diameter by incorporating the RE compositional gradient method. Furthermore, progress of machining technology enables to obtain various complicated shapes of bulk superconductors.

  10. Solid State Processing of Bulk Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Eckert, Jurgen

    1998-03-01

    Glasses are generally produced from the undercooled liquid state by rapid quenching methods or quasi-statically at slow cooling by the effective control of heterogeneous nucleation. For metallic systems, the latter method has recently led to the development of multicomponent metallic glasses with large glass forming ability and a wide supercooled liquid region before crystallization. Large-scale bulk samples can now be produced by conventional casting techniques. These materials exhibit advanced engineering properties such as excellent wear behavior, almost theoretical strength and good corrosion resistance, and are highly processable at temperatures above the glass transition temperature. As an alternative to quenching or casting techniques, glass formation can also be achieved by solid state processing without passing through the liquid state. Therefore, mechanical alloying as a special form of solid state reaction technique and subsequent consolidation of the resulting powders above the glass transition temperature can be used to prepare bulk metallic glasses through the powder metallurgy route. This paper surveys results of studies regarding the factors governing glass formation by solid state processing. The thermal stability of mechanically alloyed powders is compared with data for melt quenched samples, showing that basically the same glassy state can be reached approaching it from the liquid or the solid state. Special emphasis is given to the glass forming ranges achievable by the different techniques, and to preparation of nanostructured composite materials based on glassy alloys. The results are discussed with respect to the influence of processing conditions, impurity effects and heterogeneous nucleation of crystalline phases. Examples for consolidated bulk samples from mechanically alloyed powders are presented and compared with data for cast bulk specimens.

  11. Control of ferroelectricity and magnetism in multi-ferroic BiFeO3 by epitaxial strain

    PubMed Central

    Sando, D.; Agbelele, A.; Daumont, C.; Rahmedov, D.; Ren, W.; Infante, I. C.; Lisenkov, S.; Prosandeev, S.; Fusil, S.; Jacquet, E.; Carrétéro, C.; Petit, S.; Cazayous, M.; Juraszek, J.; Le Breton, J.-M.; Bellaiche, L.; Dkhil, B.; Barthélémy, A.; Bibes, M.

    2014-01-01

    Recently, strain engineering has been shown to be a powerful and flexible means of tailoring the properties of ABO3 perovskite thin films. The effect of epitaxial strain on the structure of the perovskite unit cell can induce a host of interesting effects, these arising from either polar cation shifts or rotation of the oxygen octahedra, or both. In the multi-ferroic perovskite bismuth ferrite (BiFeO3–BFO), both degrees of freedom exist, and thus a complex behaviour may be expected as one plays with epitaxial strain. In this paper, we review our results on the role of strain on the ferroic transition temperatures and ferroic order parameters. We find that, while the Néel temperature is almost unchanged by strain, the ferroelectric Curie temperature strongly decreases as strain increases in both the tensile and compressive ranges. Also unexpected is the very weak influence of strain on the ferroelectric polarization value. Using effective Hamiltonian calculations, we show that these peculiar behaviours arise from the competition between antiferrodistortive and polar instabilities. Finally, we present results on the magnetic order: while the cycloidal spin modulation present in the bulk survives in weakly strained films, it is destroyed at large strain and replaced by pseudo-collinear antiferromagnetic ordering. We discuss the origin of this effect and give perspectives for devices based on strain-engineered BiFeO3. PMID:24421372

  12. Defect dipole induced large recoverable strain and high energy-storage density in lead-free Na0.5Bi0.5TiO3-based systems

    NASA Astrophysics Data System (ADS)

    Cao, Wenping; Li, Weili; Feng, Yu; Bai, Terigele; Qiao, Yulong; Hou, Yafei; Zhang, Tiandong; Yu, Yang; Fei, Weidong

    2016-05-01

    In this letter, we propose an effective route to obtain large recoverable strain, purely electrostrictive effects and high energy-storage density by inducing defect dipoles into Na0.5Bi0.5TiO3 (NBT)-based relaxor ferroelectrics. It has been found that pinched and double polarization hysteresis loops with high maximum polarization (Pmax) and negligible remanent polarization (Pr) can be observed due to the presence of acceptor-induced defect dipoles. A large recoverable strain of 0.24% with very little hysteresis and high electrostriction coefficient of 0.022 m4 C2 with purely electrostrictive characteristics were acquired when 11 mol. ‰ Mn-doped. Meanwhile, a high recoverable energy density of 1.06 J/cm3 with excellent temperature stability was obtained at the same composition owing to the enlarged value of Pmax-Pr (36.8 μC/cm2) and relatively high electric field (95 kV/cm). Our achievement can open up the exciting opportunities for ferroelectric materials in high-precision positioning devices and high electric power pulse energy storage applications.

  13. Comparison of large-scale mammalian cell culture systems with egg culture for the production of influenza virus A vaccine strains.

    PubMed

    Tree, J A; Richardson, C; Fooks, A R; Clegg, J C; Looby, D

    2001-05-14

    Different types of microcarriers were assessed for the large-scale culture of influenza virus in the Madin-Darby canine kidney (MDCK) cells. Both porous and solid carriers were examined. A higher titre of influenza A/PR8/34 virus was recovered from cultures using solid (1.3x10(9) PFU per ml) rather than porous carriers (4.0x10(8) PFU per ml). High titres of virus (1.0x10(9) PFU per ml) were also obtained from roller bottle cultures of MDCK cells and the traditional culture technique using embryonated hens' eggs (3.9x10(9) PFU per ml). We found that solid carriers composed of dextran with a positive charge are the most suitable carriers for the large-scale growth of influenza A virus in MDCK cells using serum-free media. PMID:11348709

  14. Unprecedented Melioidosis Cases in Northern Australia Caused by an Asian Burkholderia pseudomallei Strain Identified by Using Large-Scale Comparative Genomics

    PubMed Central

    Smith, Emma J.; MacHunter, Barbara; Harrington, Glenda; Theobald, Vanessa; Hall, Carina M.; Hornstra, Heidie M.; McRobb, Evan; Podin, Yuwana; Mayo, Mark; Sahl, Jason W.; Wagner, David M.; Keim, Paul; Kaestli, Mirjam; Currie, Bart J.

    2015-01-01

    Melioidosis is a disease of humans and animals that is caused by the saprophytic bacterium Burkholderia pseudomallei. Once thought to be confined to certain locations, the known presence of B. pseudomallei is expanding as more regions of endemicity are uncovered. There is no vaccine for melioidosis, and even with antibiotic administration, the mortality rate is as high as 40% in some regions that are endemic for the infection. Despite high levels of recombination, phylogenetic reconstruction of B. pseudomallei populations using whole-genome sequencing (WGS) has revealed surprisingly robust biogeographic separation between isolates from Australia and Asia. To date, there have been no confirmed autochthonous melioidosis cases in Australia caused by an Asian isolate; likewise, no autochthonous cases in Asia have been identified as Australian in origin. Here, we used comparative genomic analysis of 455 B. pseudomallei genomes to confirm the unprecedented presence of an Asian clone, sequence type 562 (ST-562), in Darwin, northern Australia. First observed in Darwin in 2005, the incidence of melioidosis cases attributable to ST-562 infection has steadily risen, and it is now a common strain in Darwin. Intriguingly, the Australian ST-562 appears to be geographically restricted to a single locale and is genetically less diverse than other common STs from this region, indicating a recent introduction of this clone into northern Australia. Detailed genomic and epidemiological investigations of new clinical and environmental B. pseudomallei isolates in the Darwin region and ST-562 isolates from Asia will be critical for understanding the origin, distribution, and dissemination of this emerging clone in northern Australia. PMID:26607593

  15. Unprecedented Melioidosis Cases in Northern Australia Caused by an Asian Burkholderia pseudomallei Strain Identified by Using Large-Scale Comparative Genomics.

    PubMed

    Price, Erin P; Sarovich, Derek S; Smith, Emma J; MacHunter, Barbara; Harrington, Glenda; Theobald, Vanessa; Hall, Carina M; Hornstra, Heidie M; McRobb, Evan; Podin, Yuwana; Mayo, Mark; Sahl, Jason W; Wagner, David M; Keim, Paul; Kaestli, Mirjam; Currie, Bart J

    2016-02-01

    Melioidosis is a disease of humans and animals that is caused by the saprophytic bacterium Burkholderia pseudomallei. Once thought to be confined to certain locations, the known presence of B. pseudomallei is expanding as more regions of endemicity are uncovered. There is no vaccine for melioidosis, and even with antibiotic administration, the mortality rate is as high as 40% in some regions that are endemic for the infection. Despite high levels of recombination, phylogenetic reconstruction of B. pseudomallei populations using whole-genome sequencing (WGS) has revealed surprisingly robust biogeographic separation between isolates from Australia and Asia. To date, there have been no confirmed autochthonous melioidosis cases in Australia caused by an Asian isolate; likewise, no autochthonous cases in Asia have been identified as Australian in origin. Here, we used comparative genomic analysis of 455 B. pseudomallei genomes to confirm the unprecedented presence of an Asian clone, sequence type 562 (ST-562), in Darwin, northern Australia. First observed in Darwin in 2005, the incidence of melioidosis cases attributable to ST-562 infection has steadily risen, and it is now a common strain in Darwin. Intriguingly, the Australian ST-562 appears to be geographically restricted to a single locale and is genetically less diverse than other common STs from this region, indicating a recent introduction of this clone into northern Australia. Detailed genomic and epidemiological investigations of new clinical and environmental B. pseudomallei isolates in the Darwin region and ST-562 isolates from Asia will be critical for understanding the origin, distribution, and dissemination of this emerging clone in northern Australia. PMID:26607593

  16. Flexible strain sensor for air muscles using polypyrrole coated rubber

    NASA Astrophysics Data System (ADS)

    Tjahyono, Arief P.; Aw, Kean C.; Travas-Sejdic, Jadranka; Li, K. C.

    2010-04-01

    A novel flexible large strain sensor was developed to be use with an air muscle. A piece of butyl rubber was coated with the conducting polymer, polypyrrole through bulk solution and chemical vapour deposition method. The strain sensor was able to response to sudden movements represented by the multiple step functions of the applied strain. Consistency of the sensor's output was studied and the average error in the change of resistance was calculated to be 0.32% and 0.72% for elongation and contraction respectively for the sample made using chemical vapour deposition. However, a hysteresis was observed for this sample for a single cycle of elongation and contraction with the highest error calculated to be 3.2% at a 0% applied strain. SEM images showed the propagation of surface micro-cracks as the cause of the variation in surface resistance with applied strain. In addition, slower relaxation rate of the rubber prevented the surface micro-cracks to open and close at the same rate. The idea of utilizing conducting polymer coating can be applied to the inner rubber tube of the air muscle. As such, a complete integration between actuator and sensor can be realized.

  17. 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

  18. Mechanical properties of Gd123 superconducting bulks at 77 K

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Murakami, A.

    2012-05-01

    Mechanical properties of melt-grown GdBa2Cu3Ox (Gd123) large single-domain superconducting bulks with 10 wt% of Ag2O and 0.5 wt% of Pt have been evaluated at 77 K through flexural tests, on specimens cut from the samples, in order to estimate the mechanical properties of the Gd123 material without metal substrates, buffer layers or stabilization layers. The densified bulk was 46 mm in diameter and 25 mm in thickness, with low void density, and the standard bulk was around the same size, with voids. The results show that the mechanical properties of the densified Gd123 bulk with low void density are better than those of the standard Gd123 bulk with voids. We also compared the mechanical properties of as-grown bulks with those of annealed bulks. The relations between the microstructure and the flexural strength or the fracture toughness of the densified Gd123 bulk have been shown.

  19. Modelling of bulk superconductor magnetization

    NASA Astrophysics Data System (ADS)

    Ainslie, M. D.; Fujishiro, H.

    2015-05-01

    This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.

  20. Revealing ultralarge and localized elastic lattice strains in Nb nanowires embedded in NiTi matrix

    PubMed Central

    Zang, Ketao; Mao, Shengcheng; Cai, Jixiang; Liu, Yinong; Li, Haixin; Hao, Shijie; Jiang, Daqiang; Cui, Lishan

    2015-01-01

    Freestanding nanowires have been found to exhibit ultra-large elastic strains (4 to 7%) and ultra-high strengths, but exploiting their intrinsic superior mechanical properties in bulk forms has proven to be difficult. A recent study has demonstrated that ultra-large elastic strains of ~6% can be achieved in Nb nanowires embedded in a NiTi matrix, on the principle of lattice strain matching. To verify this hypothesis, this study investigated the elastic deformation behavior of a Nb nanowire embedded in NiTi matrix by means of in situ transmission electron microscopic measurement during tensile deformation. The experimental work revealed that ultra-large local elastic lattice strains of up to 8% are induced in the Nb nanowire in regions adjacent to stress-induced martensite domains in the NiTi matrix, whilst other parts of the nanowires exhibit much reduced lattice strains when adjacent to the untransformed austenite in the NiTi matrix. These observations provide a direct evidence of the proposed mechanism of lattice strain matching, thus a novel approach to designing nanocomposites of superior mechanical properties. PMID:26625854

  1. 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.

  2. Homogeneous crystal-rich vs. zoned crystal-poor ignimbrites: how much strain accumulates in large magma reservoirs between a new magma recharge and eruption? (Invited)

    NASA Astrophysics Data System (ADS)

    Huber, C.; Bachmann, O.; Dufek, J.; Manga, M.

    2010-12-01

    Silicic volcanic fields often display two different types of deposits: (1) crystal-rich dacitic magmas that display a striking homogeneity at the hand-sample scale and (2 dominantly crystal-poor, rhyolitic magmas that commonly grade into more mafic and more crystal-rich magmas towards the end of the eruption. An well-documented example of this dichotomy is the Central San Juan Volcanic Field (Colorado, USA), where, from the 9 major ignimbrites erupted during the climactic stage (~28.6 to 26.9 Ma), 4 occur as zoned crystal-poor to crystal-rich units and the remaining 5 form crystal-rich homogeneous deposits (make sure you explain what zoned means). In this presentation, we discuss different thermal and mechanical processes that influence the homogeneity of magmas as they evolve in shallow reservoirs. For magma bodies that are able to convect, we discuss the effect of stirring and introduce a new metric for their homogeneity for time-dependent convection. We show that the strain accumulated during 5-10 convective overturns is necessary to homogenize a magma to the hand-sample scale. In contrast, crystal-rich magmas do not experience any/enough stirring as they reach a rigid mush state. For these magmas, we discuss the effect of latent heat buffering as an agent for homogenization of temperature and crystallinity near the solidus. In order to become eruptible again, a crystal mush requires a reactivation event usually, usually attributed to the injection of new, hotter magma. We show that the time required to reactivate a mush, in every relevant case, greatly exceeds the time required to accumulate 5-10 overturns for the part of the mush that is able to convect. This difference in time-scales explains why reactivated mushes are inherently homogenous when they erupt. On the other hand, dominantly crystal-poor magmas do not need to be reactivated. Their homogeneity is governed by the competition between the time between the introduction of heterogeneities (for example

  3. Utilisation of ISA Reverse Genetics and Large-Scale Random Codon Re-Encoding to Produce Attenuated Strains of Tick-Borne Encephalitis Virus within Days

    PubMed Central

    Aubry, Fabien; Gould, Ernest A.; de Lamballerie, Xavier

    2016-01-01

    Large-scale codon re-encoding is a new method of attenuating RNA viruses. However, the use of infectious clones to generate attenuated viruses has inherent technical problems. We previously developed a bacterium-free reverse genetics protocol, designated ISA, and now combined it with large-scale random codon-re-encoding method to produce attenuated tick-borne encephalitis virus (TBEV), a pathogenic flavivirus which causes febrile illness and encephalitis in humans. We produced wild-type (WT) and two re-encoded TBEVs, containing 273 or 273+284 synonymous mutations in the NS5 and NS5+NS3 coding regions respectively. Both re-encoded viruses were attenuated when compared with WT virus using a laboratory mouse model and the relative level of attenuation increased with the degree of re-encoding. Moreover, all infected animals produced neutralizing antibodies. This novel, rapid and efficient approach to engineering attenuated viruses could potentially expedite the development of safe and effective new-generation live attenuated vaccines. PMID:27548676

  4. Statistical determination of bulk flow motions

    SciTech Connect

    Song, Yong-Seon; Sabiu, Cristiano G.; Nichol, Robert C.; Miller, Christopher J. E-mail: cris.sabiu@port.ac.uk E-mail: cmiller@noao.edu

    2010-01-01

    We present here a new parameterization for the bulk motions of galaxies and clusters (in the linear regime) that can be measured statistically from the shape and amplitude of the two-dimensional two-point correlation function. We further propose the one-dimensional velocity dispersion (v{sub p}) of the bulk flow as a complementary measure of redshift-space distortions, which is model-independent and not dependent on the normalisation method. As a demonstration, we have applied our new methodology to the C4 cluster catalogue constructed from Data Release Three (DR3) of the Sloan Digital Sky Survey. We find v{sub p} = 270{sup +433} km/s (also consistent with v{sub p} = 0) for this cluster sample (at z-bar = 0.1), which is in agreement with that predicted for a WMAP5-normalised ΛCDM model (i.e., v{sub p}(ΛCDM) = 203 km/s). This measurement does not lend support to recent claims of excessive bulk motions ( ≅ 1000 km/s) which appear in conflict with ΛCDM, although our large statistical error cannot rule them out. From the measured coherent evolution of v{sub p}, we develop a technique to re-construct the perturbed potential, as well as estimating the unbiased matter density fluctuations and scale-independent bias.

  5. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading.

    PubMed

    Lambert, P K; Hustedt, C J; Vecchio, K S; Huskins, E L; Casem, D T; Gruner, S M; Tate, M W; Philipp, H T; Woll, A R; Purohit, P; Weiss, J T; Kannan, V; Ramesh, K T; Kenesei, P; Okasinski, J S; Almer, J; Zhao, M; Ananiadis, A G; Hufnagel, T C

    2014-09-01

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ~10(3)-10(4) s(-1) in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10-20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (~40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation. PMID:25273733

  6. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

    SciTech Connect

    Lambert, P. K.; Hustedt, C. J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C.; Vecchio, K. S.; Huskins, E. L.; Casem, D. T.; Gruner, S. M.; Tate, M. W.; Philipp, H. T.; Purohit, P.; Weiss, J. T.; Woll, A. R.; Kannan, V.; Ramesh, K. T.; Kenesei, P.; Okasinski, J. S.; Almer, J.

    2014-09-15

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼10{sup 3}–10{sup 4} s{sup −1} in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

  7. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

    PubMed Central

    Lambert, P. K.; Hustedt, C. J.; Vecchio, K. S.; Huskins, E. L.; Casem, D. T.; Gruner, S. M.; Tate, M. W.; Philipp, H. T.; Woll, A. R.; Purohit, P.; Weiss, J. T.; Kannan, V.; Ramesh, K. T.; Kenesei, P.; Okasinski, J. S.; Almer, J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C.

    2014-01-01

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼103–104 s−1 in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation. PMID:25273733

  8. Comparison of bulk- and surface-micromachined pressure sensors

    SciTech Connect

    Eaton, W.P.; Smith, J.H.; Monk, D.J.; O`Brien, G.; Miller, T.F.

    1998-08-01

    Two piezoresistive micromachined pressure sensors were compared: a commercially available bulk-micromachined (BM) pressure sensor and an experimental surface-micromachined (SM) pressure sensor. While the SM parts had significantly smaller die sizes, they were outperformed in most areas by the BM parts. This was due primarily to the smaller piezoresistive gauge factor in the polysilicon piezoresistors in the SM parts compared to the single crystal strain gauge used in the BM parts.

  9. 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.

  10. Dissection of quantitative traits by bulk segregant mapping in a protoploid yeast species.

    PubMed

    Sigwalt, Anastasie; Caradec, Claudia; Brion, Christian; Hou, Jing; de Montigny, Jacky; Jung, Paul; Fischer, Gilles; Llorente, Bertrand; Friedrich, Anne; Schacherer, Joseph

    2016-08-01

    Since more than a decade ago, Saccharomyces cerevisiae has been used as a model to dissect complex traits, revealing the genetic basis of a large number of traits in fine detail. However, to have a more global view of the genetic architecture of traits across species, the examination of the molecular basis of phenotypes within non-conventional species would undoubtedly be valuable. In this respect, the Saccharomycotina yeasts represent ideal and potential non-model organisms. Here we sought to assess the feasibility of genetic mapping by bulk segregant analysis in the protoploid Lachancea kluyveri (formerly S. kluyveri) yeast species, a distantly related species to S. cerevisiae For this purpose, we designed a fluorescent mating-type marker, compatible with any mating-competent strains representative of this species, to rapidly create a large population of haploid segregants (>10(5) cells). Quantitative trait loci can be mapped by selecting and sequencing an enriched pool of progeny with extreme phenotypic values. As a test bed, we applied this strategy and mapped the causal loci underlying halotolerance phenotypes in L. kluyveri Overall, this study demonstrates that bulk segregant mapping is a powerful way for investigating the genetic basis of natural variations in non-model yeast organisms and more precisely in L. kluyveri. PMID:27371856

  11. Ovarian tissue characterization using bulk optical properties

    NASA Astrophysics Data System (ADS)

    Tavakoli, B.; Xu, Y.; Zhu, Q.

    2013-03-01

    Ovarian cancer, the deadliest of all gynecologic cancers, is not often found in its early stages due to few symptoms and no reliable screening test. Optical imaging has a great potential to improve the ovarian cancer detection and diagnosis. In this study we have characterized the bulk optical properties of 26 ex-vivo human ovaries using a Diffuse Optical Tomography system. The quantitative values indicated that, in the postmenopausal group, malignant ovaries showed significantly lower scattering coefficient than normal ones. The scattering parameter is largely related to the collagen content that has shown a strong correlation with the cancer development.

  12. 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.

  13. Improving bulk microphysics parameterizations in simulations of aerosol effects

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Fan, Jiwen; Zhang, Renyi; Leung, L. Ruby; Franklin, Charmaine

    2013-06-01

    To improve the microphysical parameterizations for simulations of the aerosol effects in regional and global climate models, the Morrison double-moment bulk microphysical scheme presently implemented in the Weather Research and Forecasting model is modified by replacing the prescribed aerosols in the original bulk scheme (Bulk-OR) with a prognostic double-moment aerosol representation to predict both aerosol number concentration and mass mixing ratio (Bulk-2M). Sensitivity modeling experiments are performed for two distinct cloud regimes: maritime warm stratocumulus clouds (Sc) over southeast Pacific Ocean from the VOCALS project and continental deep convective clouds in the southeast of China. The results from Bulk-OR and Bulk-2M are compared against atmospheric observations and simulations produced by a spectral bin microphysical scheme (SBM). The prescribed aerosol approach (Bulk-OR) produces unreliable aerosol and cloud properties throughout the simulation period, when compared to the results from those using Bulk-2M and SBM, although all of the model simulations are initiated by the same initial aerosol concentration on the basis of the field observations. The impacts of the parameterizations of diffusional growth and autoconversion of cloud droplets and the selection of the embryonic raindrop radius on the performance of the bulk microphysical scheme are also evaluated by comparing the results from the modified Bulk-2M with those from SBM simulations. Sensitivity experiments using four different types of autoconversion schemes reveal that the autoconversion parameterization is crucial in determining the raindrop number, mass concentration, and drizzle formation for warm stratocumulus clouds. An embryonic raindrop size of 40 µm is determined as a more realistic setting in the autoconversion parameterization. The saturation adjustment employed in calculating condensation/evaporation in the bulk scheme is identified as the main factor responsible for the large

  14. Unusual room-temperature compressive plasticity in nanocrystal-toughened bulk copper-zirconium glass

    NASA Astrophysics Data System (ADS)

    Inoue, A.; Zhang, W.; Tsurui, T.; Yavari, A. R.; Greer, A. L.

    2005-05-01

    Cast Cu50Zr50 alloy rods with a diameter of 1 mm have been found to consist of a glassy phase containing fine crystalline particles with a size of about 5 nm. They have a glass transition temperature Tg of 675 K, and a large supercooled-liquid region extending 57 K above Tg. The rods exhibit a high yield strength of 1860 MPa and a Young's modulus of 104 GPa. Because they contain a dispersion of embedded nanocrystals, the as-cast bulk metallic glass rods can sustain a compressive plastic strain at room temperature of more than 50%, an exceptional value which is explicable by compensation of any shear softening by nanocrystal coalescence and pinning of shear bands.

  15. Large strain and pyroelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics prepared by partial oxalate route

    NASA Astrophysics Data System (ADS)

    Fang, Bijun; Qian, Kun; Chen, Zhihui; Yuan, Ningyi; Ding, Jianning; Zhao, Xiangyong; Xu, Haiqing; Luo, Haosu

    2014-06-01

    Partial oxalate route is an efficient method to synthesize complex perovskite ferroelectric ceramics, in which the synthesized (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) ceramics exhibit rather pure perovskite structure, densified microstructure morphology, and excellent dielectric and piezoelectric properties. The PMN-PT ceramics synthesized by the partial oxalate route exhibit rather symmetric strain-electric (S-E) field hysteresis loops, where the strain is large and far less than saturated at 2 kV/mm. The PMN-PT ceramics exhibit excellent pyroelectric properties, in which the values of the pyroelectric coefficient and the calculated pyroelectric figures of merit maintain almost stable over the frequency range of 100 Hz-2000 Hz, and vary differently depending on composition with the increase of temperature. Such investigations reveal that high-performance piezoelectric and pyroelectric devices can be prepared by the partial oxalate route in low production cost.

  16. Metrology Challenges for 45 nm Strained-Si Devices

    NASA Astrophysics Data System (ADS)

    Vartanian, V.; Sadaka, M.; Zollner, S.; Thean, A. V.-Y.; White, T.; Nguyen, B.-Y.; Zavala, M.; McCormick, L.; Prabhu, L.; Eades, D.; Parsons, S.; Collard, H.; Kim, K.; Jiang, J.; Dhandapani, V.; Hildreth, J.; Powers, R.; Spencer, G.; Ramani, N.; Mogab, J.; Kottke, M.; Canonico, M.; Xie, Q.; Wang, X.-D.; Vella, J.; Contreras, L.; Theodore, D.; Lu, B.; Kriske, T.; Gregory, R.; Liu, R.

    2005-09-01

    The semiconductor industry has sustained its historical exponential performance gains by aggressively scaling transistor dimensions. However, as devices approach sub-100 nm dimensions, scaling becomes more challenging and new materials are required to overcome the fundamental physical limits imposed by existing materials. For example, as power supply voltages continue to decrease with successive scaling, enhanced carrier mobility using biaxially tensile-strained-Si on SOI or on bulk substrates have become viable options to sustain continual drive current increases without traditional scaling. Although the addition of strained-Si to conventional MOSFET devices is compatible with existing mainstream CMOS process technology, there are new device and process integration challenges, wafer quality monitoring demands, and stringent requirements for film morphology and strain uniformity, imposing new demands on material characterization. Material requirements for strained-Si CMOS devices include homogeneous Si or SiGe film thickness, Ge composition, strain distribution to maintain uniform device performance. Also important are having good interface quality and low defect density (misfit and threading dislocation densities below 1e4/cm2) to ensure high minority carrier lifetimes and transconductance, and low surface roughness (<3Å RMS) to minimize the impact of interface scattering on carrier mobilities. Non-destructive, in-line metrology techniques include spectroscopic ellipsometry (SE) for film thickness and Ge composition, xray reflectivity (XRR) for thickness, density, and roughness measurements, xray fluorescence (XRF) for Ge composition, UV-Raman spectroscopy for channel strain characterization, IR photoluminescence (PL) for defect detection, and xray diffraction (XRD) for film thickness, Ge content, and strain measurement. While most of these techniques are well established in the semiconductor industry, some will require performance enhancements and development

  17. Bulk charges in eleven dimensions

    NASA Astrophysics Data System (ADS)

    Hawking, S. W.; Taylor-Robinson, M. M.

    1998-07-01

    Eleven dimensional supergravity has electric type currents arising from the Chern-Simon and anomaly terms in the action. However the bulk charge integrates to zero for asymptotically flat solutions with topological trivial spatial sections. We show that by relaxing the boundary conditions to generalisations of the ALE and ALF boundary conditions in four dimensions one can obtain static solutions with a bulk charge. Solutions involving anomaly terms preserve between 1/16 and 1/4 of the supersymmetries but Chern-Simons fluxes generally break all of the remaining supersymmetry. One can introduce membranes with the same sign of charge into these backgrounds. This raises the possibility that these generalized membranes might decay quantum mechanically to leave just a bulk distribution of charge. Alternatively and more probably, a bulk distribution of charge can decay into a collection of singly charged membranes. Dimensional reductions of these solutions lead to novel representations of extreme black holes in four dimensions with up to four charges. We discuss how the eleven-dimensional Kaluza-Klein monopole wrapped around a space with non-zero first Pontryagin class picks up an electric charge proportional to the Pontryagin number.

  18. REL - English Bulk Data Input.

    ERIC Educational Resources Information Center

    Bigelow, Richard Henry

    A bulk data input processor which is available for the Rapidly Extensible Language (REL) English versions is described. In REL English versions, statements that declare names of data items and their interrelationships normally are lines from a terminal or cards in a batch input stream. These statements provide a convenient means of declaring some…

  19. Hanford Bulk Vitrification Technology Status

    SciTech Connect

    Witwer, Keith S.; Dysland, Eric J.; Bagaasen, Larry M.; Schlahta, Stephan N.; Kim, Dong-Sang; Schweiger, Michael J.; Hrma, Pavel R.

    2007-01-25

    Research and testing was initiated in 2003 to support the selection of a supplemental treatment technology for Hanford low-activity wastes (LAWs). AMEC’s bulk vitrification process was chosen for full-scale demonstration, and the Demonstration Bulk Vitrification System (DBVS) project was started in 2004. Also known as in-container vitrification™ (ICV™), the bulk vitrification process combines soil, liquid LAW, and additives (B2O3 and ZrO2); dries the mixture; and then vitrifies the material in a batch feed-while-melt process in a refractory lined steel container. The DBVS project was initiated with the intent to engineer, construct, and operate a full-scale bulk vitrification pilot-plant to treat LAW from Tank 241-S-109 at the U.S. Department of Energy (DOE) Hanford Site. AMEC is adapting its ICV™ technology for this application with technical and analytical support from Pacific Northwest National Laboratory (PNNL). The DBVS project is funded by the DOE Office of River Protection and administered by CH2M HILL Hanford Group, Inc. Since the beginning of the selection process in 2003, testing has utilized crucible-scale, engineering-scale, and full-scale bulk vitrification equipment. Crucible-scale testing, coupled with engineering-scale testing, helps establish process limitations of selected glass formulations. Full-scale testing provides critical design verification of the ICV™ process both before and during operation of the demonstration facility. Initial testing focused on development and validation of the baseline equipment configuration and glass formulation. Subsequent testing was focused on improvements to the baseline configuration. Many improvements have been made to the bulk vitrification system equipment configuration and operating methodology since its original inception. Challenges have been identified and met as part of the parallel testing and design process. A 100% design package for the pilot plant is complete and has been submitted to DOE

  20. Bulk viscosity of anisotropically expanding hot QCD plasma

    SciTech Connect

    Chandra, Vinod

    2011-11-01

    The bulk viscosity, {zeta} and its ratio with the shear viscosity, {zeta}/{eta} have been studied in an anisotropically expanding pure glue plasma in the presence of turbulent color fields. It has been shown that the anisotropy in the momentum distribution function of gluons, which has been determined from a linearized transport equation eventually leads to the bulk viscosity. For the isotropic (equilibrium) state, a recently proposed quasiparticle model of pure SU(3) lattice QCD equation of state has been employed where the interactions are encoded in the effective fugacity. It has been argued that the interactions present in the equation of state, significantly contribute to the bulk viscosity. Its ratio with the shear viscosity is significant even at 1.5T{sub c}. Thus, one needs to take in account the effects of the bulk viscosity while studying the hydrodynamic expansion of quark-gluon plasma in the Relativistic Heavy Ion Collider and the Large Hadron Collider.

  1. Efficiency of bulk-heterojunction organic solar cells

    PubMed Central

    Scharber, M.C.; Sariciftci, N.S.

    2013-01-01

    During the last years the performance of bulk heterojunction solar cells has been improved significantly. For a large-scale application of this technology further improvements are required. This article reviews the basic working principles and the state of the art device design of bulk heterojunction solar cells. The importance of high power conversion efficiencies for the commercial exploitation is outlined and different efficiency models for bulk heterojunction solar cells are discussed. Assuming state of the art materials and device architectures several models predict power conversion efficiencies in the range of 10–15%. A more general approach assuming device operation close to the Shockley–Queisser-limit leads to even higher efficiencies. Bulk heterojunction devices exhibiting only radiative recombination of charge carriers could be as efficient as ideal inorganic photovoltaic devices. PMID:24302787

  2. Bulk undercooling, nucleation, and macrosegregation of Pb-Sn alloys

    NASA Technical Reports Server (NTRS)

    Degroh, H. C., III; Laxmanan, V.

    1988-01-01

    Preliminary ground-based studies on the undercooling behavior of large samples (23 g) of lead-tin alloys are presented. Evidence of gravity-related segregation effects is found, and a possible area for future microgravity experimentation is thus identified. Detailed descriptions of the experimental procedure used to achieve bulk undercoolings of between 0.5 and 34 K, depending on composition, are given. The bulk undercoolings obtained in this study are comparable with those found in small droplets. The large size of the present samples enabled the observation of sedimentation and other macrosegregation processes.

  3. Tunable thermoelectric transport in nanomeshes via elastic strain engineering

    SciTech Connect

    Piccione, Brian; Gianola, Daniel S.

    2015-03-16

    Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermal management.

  4. Tunable thermoelectric transport in nanomeshes via elastic strain engineering

    NASA Astrophysics Data System (ADS)

    Piccione, Brian; Gianola, Daniel S.

    2015-03-01

    Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermal management.

  5. Longitudinal bulk acoustic mass sensor

    SciTech Connect

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-20

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10{sup -15} g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  6. Bulk Superconductors in Mobile Application

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

    We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

  7. Functional characterization of mutant strains of the cyanobacterium Synechocystis sp. PCC 6803 lacking short domains within the large, lumen-exposed loop of the chlorophyll protein CP47 in photosystem II.

    PubMed

    Gleiter, H M; Haag, E; Shen, J R; Eaton-Rye, J J; Inoue, Y; Vermaas, W F; Renger, G

    1994-10-11

    Several autotrophic mutant strains of Synechocystis sp. PCC 6803 carrying short deletions or a single-site mutation within the large, lumen-exposed loop (loop E) of the chlorophyll a-binding photosystem II core protein, CP47, are analyzed for their functional properties by measuring the flash-induced pattern of thermoluminescence, oxygen yield, and fluorescence quantum yield. A physiological and biochemical characterization of these mutant strains has been given in two previous reports [Eaton-Rye, J.J., & Vermaas, W.F.J. (1991) Plant Mol. Biol. 17, 1165-1177; Haag, E., Eaton-Rye, J.J., Renger, G., & Vermaas, S. F.J. (1993) Biochemistry 32, 4444-4454]. The results of the present study show that deletion of charged and conserved amino acids in a region roughly located between residues 370 and 390 decreases the binding affinity of the extrinsic PS II-O protein to photosystem II. Marked differences with PSII-O deletion mutants are observed with respect to Ca2+ requirement and the flash-induced pattern of oxygen evolution. Under conditions where a sufficient light activation is provided, the psbB mutants assayed in this study reveal normal S-state parameters and lifetimes. The results bear two basic implications: (i) the manganese involved in water oxidation can still be bound in a functionally normal or only slightly distorted manner, and (ii) the binding of the extrinsic PS II-O protein to photosystem II is impaired in mutants carrying a deletion in the domain between residues 370 and 390, but the presence of the PS II-O protein is still of functional relevance for the PS II complex, e.g., for maintenance of a high-affinity binding site for Ca2+ and/or involvement during the process of photoactivation. PMID:7918426

  8. Stress-corrosion fatigue-crack growth in a Zr-based bulk amorphousmetal

    SciTech Connect

    Schroeder, V.; Ritchie, R.O.

    2005-09-21

    Electrochemical and mechanical experiments were conducted to analyze the environmentally-influenced cracking behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5. This study was motivated by a scientific interest in mechanisms of fatigue-crack propagation in an amorphous metal, and by a practical interest in the use of this amorphous metal in applications that take advantage of its unique properties, including high specific strength, large elastic strains and low damping. The objective of the work was to determine the rate and mechanisms of subcritical crack growth in this metallic glass in an aggressive environment. Specifically, fatigue-crack propagation behavior was investigated at a range of stress intensities in air and aqueous salt solutions by examining the effects of loading cycle, stress-intensity range, solution concentration, anion identity, solution de-aeration, and bulk electrochemical potential. Results indicate that crack growth in aqueous solution in this alloy is driven by a stress-assisted anodic reaction at the crack tip. Rate-determining steps for such behavior are reasoned to be electrochemical, stress-dependent reaction at near-threshold levels, and mass transport at higher (steady-state) growth rates.

  9. Influence of the shot-peening intensity on the structure and near-surface mechanical properties of Ti40Zr10Cu38Pd12 bulk metallic glass

    NASA Astrophysics Data System (ADS)

    González, S.; Fornell, J.; Pellicer, E.; Suriñach, S.; Baró, M. D.; Greer, A. L.; Belzunce, F. J.; Sort, J.

    2013-11-01

    Shot-peening (SP) changes the near-surface structure and mechanical properties of a Ti40Zr10Cu38Pd12 bulk metallic glass. Near the surface, the hardness, Young's modulus, and elastic strain limit are all reduced. Measurements of the heat of relaxation show that an exceptionally high stored energy of cold work can be induced, implying a large increase in free volume. At the highest SP intensity there is partial nanocrystallization enabled by the increased free volume and not by the increase in temperature.

  10. Understanding of martensitic (TiCu)-based bulk metallic glasses through deformation behavior of a binary Ti{sub 50}Cu{sub 50} martensitic alloy

    SciTech Connect

    Kim, K. B.; Song, K. A.; Zhang, X. F.; Yi, S.

    2008-06-16

    A binary Ti{sub 50}Cu{sub 50} martensitic alloy having similar atomic clusters to (TiCu)-based martensitic bulk metallic glasses presents a large plastic strain of 18.04% with high fracture strength of 1705 MPa. Detailed microstructural investigations point out that martensite embedded in {gamma}-TiCu matrix is effective to dissipate localization of the shear stress thus leading to rotational propagation, interaction, and multiplication of the shear bands. Furthermore, the propagation of microcracks formed by local stress transition during deformation is hindered by the martensite.

  11. 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.

  12. Strain effects on thermal conductivity of nanostructured silicon by Raman piezothermography

    NASA Astrophysics Data System (ADS)

    Murphy, Kathryn Fay

    A fundamental problem facing the rational design of materials is the independent control of electrical and thermal properties, with implications for a wide range of applications including thermoelectrics, solar thermal power generation, and thermal logic. One strategy for controlling transport involves manipulating the length scales which affect it. For instance, Si thermal conductivity may be reduced with relatively little change in electrical properties when the confining dimension (e.g., nanowire diameter) is small enough that heat carriers are preferentially scattered at free surfaces. However, tailoring properties by geometry or chemistry alone does not allow for on-demand modification, precluding applications which require responsive behavior such as thermal transistors, thermoelectric modules which adapt to their environmental temperature, or switchable thermal barriers. One means of tuning transport is elastic strain, which has long been exploited to improve carrier mobility in electronic devices. Uniform strain is predicted to affect thermal conductivity primarily via changes in heat capacity and phonon velocity, and crystalline defects such as vacancies or dislocations---which induce large strain gradients---should lower thermal conductivity by decreasing the phonon mean free path. Nanowires are ideal for the study of strain and defect effects due to the availability of a range of elastic strain an order of magnitude larger than in bulk and due to their small volumes. However, experimental measurements of strain-mediated thermal conductivity in nanowires have been limited due to the complexity of simultaneously applying and measuring stress or strain, heating, and measuring temperature. In this dissertation, we measure strain effects on thermal conductivity using a novel non-contact approach which we name Raman piezothermography. We apply a uniaxial load to individual Si nanowires, Si thin films, and Si micromeshes under a confocal mu-Raman microscope and

  13. A tale of two mechanisms. Strain-softening versus strain-hardening in single crystals under small stressed volumes

    DOE PAGESBeta

    Bei, Hongbin; Xia, Yuzhi; Barabash, Rozaliya; Gao, Y. F.

    2015-08-10

    Pre-straining defect-free single crystals will introduce heterogeneous dislocation nucleation sources that reduce the measured strength from the theoretical value, while pre-straining bulk samples will lead to strain hardening. Their competition is investigated by nanoindentation pop-in tests on variously pre-strained Mo single crystals with several indenter radii (~micrometer). Pre-straining primarily shifts deformation mechanism from homogeneous dislocation nucleation to a stochastic behavior, while strain hardening plays a secondary role, as summarized in a master plot of pop-in strength versus normalized indenter radius.

  14. Effective pure states for bulk quantum computation

    SciTech Connect

    Knill, E.; Chuang, I.; Laflamme, R.

    1998-05-01

    In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) [Science {bold 275}, 350 (1997)] and Cory {ital et al.} (spatial averaging) [Proc. Natl. Acad. Sci. USA {bold 94}, 1634 (1997)] for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla quantum bits, and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high-temperature and low-temperature bulk quantum computing and analyze the signal-to-noise behavior of each. Most of these algorithms require only a constant multiple of the number of experiments needed by the other methods for creating effective pure states. {copyright} {ital 1998} {ital The American Physical Society}

  15. Enhancing bulk superconductivity by engineering granular materials

    NASA Astrophysics Data System (ADS)

    Mayoh, James; García García, Antonio

    2014-03-01

    The quest for higher critical temperatures is one of the main driving forces in the field of superconductivity. Recent theoretical and experimental results indicate that quantum size effects in isolated nano-grains can boost superconductivity with respect to the bulk limit. Here we explore the optimal range of parameters that lead to an enhancement of the critical temperature in a large three dimensional array of these superconducting nano-grains by combining mean-field, semiclassical and percolation techniques. We identify a broad range of parameters for which the array critical temperature, TcArray, can be up to a few times greater than the non-granular bulk limit, Tc 0. This prediction, valid only for conventional superconductors, takes into account an experimentally realistic distribution of grain sizes in the array, charging effects, dissipation by quasiparticles and limitations related to the proliferation of thermal fluctuations for sufficiently small grains. For small resistances we find the transition is percolation driven. Whereas at larger resistances the transition occurs above the percolation threshold due to phase fluctuations. JM acknowledes support from an EPSRC Ph.D studentship, AMG acknowledges support from EPSRC, grant No. EP/I004637/1, FCT, grant PTDC/FIS/111348/2009 and a Marie Curie International Reintegration Grant PIRG07-GA-2010-268172.

  16. Perspectives on Bulk Locality in Gauge/Gravity Duality

    NASA Astrophysics Data System (ADS)

    Heemskerk, Idse J.

    2012-05-01

    In this thesis we consider the question of how local bulk physics emerges from the perspective of the boundary field theory in the supergravity limit of gauge/gravity duality. We take three different approaches to this problem, which in retrospect correspond to the different ways of thinking about quantum field theory in the bulk. In the S-matrix approach, we study crossing constraints on two-to-two scattering amplitudes, and provide evidence for the conjecture that a large N expansion and a hierarchy in the spectrum of operator dimension are sufficient conditions for a conformal theory to have a local bulk dual. In the path integral approach we attempt to connect the holographic and Wilsonian renormalization groups. An important role for multi-trace operators is discovered. Although locality remains unexplained, several parallels between holographic and Wilsonian renormalization are made and a physical picture of how the bulk dynamics might emerge from the perspective of the renormalization group is sketched. In the last part we consider the construction of the bulk field operators in terms of smeared boundary operators. Aside from extending the previous work on this construction in several directions, we formulate conditions for obtaining the field operators without already knowing the bulk dynamics and address some paradoxes related to a cat inside a black hole.

  17. 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

  18. High temperature static strain gage development

    NASA Technical Reports Server (NTRS)

    Hulse, C. O.; Bailey, R. S.; Grant, H. P.; Anderson, W. L.; Przybyszewski, J. S.

    1991-01-01

    Final results are presented from a program to develop a thin film static strain gage for use on the blades and vanes of running, test stand gas turbine engines with goals of an 3 x 3 mm gage area and total errors of less than 10 pct. of + or - 2,000 microstrain after 50 hrs at 1250 K. Pd containing 13 Wt. pct. Cr was previously identified as a new strain sensor alloy that appeared to be potentially usable to 1250 K. Subsequently, it was discovered, in contrast with its behavior in bulk, that Pd-13Cr suffered from oxidation attack when prepared as a 4.5 micron thick thin film. Continuing problems with electrical leakage to the substrate and the inability of sputtered alumina overcoats to prevent oxidation led to the discovery that sputtered alumina contains appreciable amounts of entrapped argon. After the argon has been exsolved by heating to elevated temperatures, the alumina films undergo a linear shrinkage of about 2 pct. resulting in formation of cracks. These problems can be largely overcome by sputtering the alumina with the substrate heated to 870 K. With 2 micron thick hot sputtered alumina insulation and overcoat films, total 50 hr drifts of about 100 microstrain (2 tests) and about 500 microstrain (1 test) were observed at 1000 and 1100 K, respectively. Results of tests on complete strain gage systems on constant moment bend bars with Pd temperature compensation grids revealed that oxidation of the Pd grid was a major problem even when the grid was overcoated with a hot or cold sputtered alumina overcoat.

  19. Bulk Moisture and Salinity Sensor

    NASA Technical Reports Server (NTRS)

    Nurge, Mark; Monje, Oscar; Prenger, Jessica; Catechis, John

    2013-01-01

    Measurement and feedback control of nutrient solutions in plant root zones is critical to the development of healthy plants in both terrestrial and reduced-gravity environments. In addition to the water content, the amount of fertilizer in the nutrient solution is important to plant health. This typically requires a separate set of sensors to accomplish. A combination bulk moisture and salinity sensor has been designed, built, and tested with different nutrient solutions in several substrates. The substrates include glass beads, a clay-like substrate, and a nutrient-enriched substrate with the presence of plant roots. By measuring two key parameters, the sensor is able to monitor both the volumetric water content and salinity of the nutrient solution in bulk media. Many commercially available moisture sensors are point sensors, making localized measurements over a small volume at the point of insertion. Consequently, they are more prone to suffer from interferences with air bubbles, contact area of media, and root growth. This makes it difficult to get an accurate representation of true moisture content and distribution in the bulk media. Additionally, a network of point sensors is required, increasing the cabling, data acquisition, and calibration requirements. measure the dielectric properties of a material in the annular space of the vessel. Because the pore water in the media often has high salinity, a method to measure the media moisture content and salinity simultaneously was devised. Characterization of the frequency response for capacitance and conductance across the electrodes was completed for 2-mm glass bead media, 1- to 2-mm Turface (a clay like media), and 1- to 2-mm fertilized Turface with the presence of root mass. These measurements were then used to find empirical relationships among capacitance (C), the dissipation factor (D), the volumetric water content, and the pore water salinity.

  20. Soil water sensor response to bulk electrical conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water monitoring using electromagnetic (EM) sensors can facilitate observations of water content at high temporal and spatial resolutions. These sensors measure soil dielectric permittivity (Ka) which is largely a function of volumetric water content. However, bulk electrical conductivity BEC c...

  1. Time-resolved spectra of bulk titanium combustion

    NASA Technical Reports Server (NTRS)

    Runyan, C. C.; Moulder, J. C.; Clark, A. F.

    1974-01-01

    Some preliminary spectroscopic results of an investigation of the radiation from bulk specimens of burning titanium are presented. The use of larger stationary specimens is shown to have considerably eased some of the experimental difficulties associated with metal combustion research and to approximate more closely the conditions prevailing in large-scale accidental metal fires.

  2. Enhancing polarization by electrode-controlled strain relaxation in PbTiO{sub 3} heterostructures

    SciTech Connect

    Peräntie, J. Stratulat, M. S.; Hannu, J.; Jantunen, H.; Tyunina, M.

    2016-01-01

    A large remanent polarization close to theoretical value 80 μC/cm{sup 2} of bulk PbTiO{sub 3} is achieved in epitaxial heterostructures of (120–600)-nm-thick PbTiO{sub 3} films grown by pulsed laser deposition on (001) SrTiO{sub 3} substrate using a 100-nm-thick SrRuO{sub 3} bottom electrode layer. The heterostructures employing a 50-nm-thick electrode exhibit a significantly smaller polarization of ≤60 μC/cm{sup 2}. A detailed x-ray diffraction analysis of the crystal structure allows for relating this large polarization to electrode-controlled relaxation of epitaxial strain in PbTiO{sub 3}. Based on the observed results, we anticipate that the electrode-promoted strain relaxation can be used to enhance polarization in other epitaxial ferroelectric films.

  3. Bulk Forming of Industrial Micro Components in Conventional Metals and Bulk Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Arentoft, M.; Paldan, N. A.; Eriksen, R. S.; Gastaldi, T.; Wert, J. A.; Eldrup, M.

    2007-04-01

    For production of micro components in large numbers, forging is an interesting and challenging process. The conventional metals like silver, steel and aluminum often require multi-step processes, but high productivity and increased strength justify the investment. As an alternative, bulk metallic glasses will at elevated temperatures behave like a highly viscous liquid, which can easily form even complicated geometries in 1 step. The strengths and limitations of forming the 2 materials are analyzed for a micro 3D component in a silver alloy and an Mg-Cu-Y BMG.

  4. Bulk Forming of Industrial Micro Components in Conventional Metals and Bulk Metallic Glasses

    SciTech Connect

    Arentoft, M.; Paldan, N. A.; Eriksen, R. S.; Gastaldi, T.; Wert, J. A.; Eldrup, M.

    2007-04-07

    For production of micro components in large numbers, forging is an interesting and challenging process. The conventional metals like silver, steel and aluminum often require multi-step processes, but high productivity and increased strength justify the investment. As an alternative, bulk metallic glasses will at elevated temperatures behave like a highly viscous liquid, which can easily form even complicated geometries in 1 step. The strengths and limitations of forming the 2 materials are analyzed for a micro 3D component in a silver alloy and an Mg-Cu-Y BMG.

  5. In-plane uniaxial magnetic anisotropy induced by anisotropic strain relaxation in high lattice-mismatched Dy/Sc superlattices

    NASA Astrophysics Data System (ADS)

    Benito, L.; Ballesteros, C.; Ward, R. C. C.

    2014-04-01

    We report on the magnetic and structural characterization of high lattice-mismatched [Dy2nm/SctSc] superlattices, with variable Sc thickness tSc= 2-6 nm. We find that the characteristic in-plane effective hexagonal magnetic anisotropy K66,ef reverses sign and undergoes a dramatic reduction, attaining values of ≈13-24 kJm-3, when compared to K66=-0.76 MJm-3 in bulk Dy. As a result, the basal plane magnetic anisotropy is dominated by a uniaxial magnetic anisotropy (UMA) unfound in bulk Dy, which amounts to ≈175-142 kJm-3. We attribute the large downsizing in K66,ef to the compression epitaxial strain, which generates a competing sixfold magnetoelastic (MEL) contribution to the magnetocrystalline (strain-free) magnetic anisotropy. Our study proves that the in-plane UMA is caused by the coupling between a giant symmetry-breaking MEL constant Mγ ,22≈1 GPa and a morphic orthorhombiclike strain ɛγ ,1≈10-4, whose origin resides on the arising of an in-plane anisotropic strain relaxation process of the pseudoepitaxial registry between the nonmagnetic bottom layers in the superstructure. This investigation shows a broader perspective on the crucial role played by epitaxial strains at engineering the magnetic anisotropy in multilayers.

  6. XRD investigation of the strain/stress state of ion-irradiated crystals

    NASA Astrophysics Data System (ADS)

    Debelle, Aurélien; Declémy, Alain

    2010-05-01

    In this work, it is demonstrated that XRD is a powerful technique for the study of ion-irradiated materials. For this purpose, XRD experiments have been performed under different configurations on a <1 0 0>-oriented yttria-stabilized zirconia single crystal implanted with 300 keV caesium-ions at 3 × 10 14 cm -2. Initially, it is demonstrated that the depth strain profile can be determined from the refinement of a symmetric θ-2 θ scan. Moreover, in order to explore the whole XRD data, a model that describes the strain/stress state of the damaged layer is proposed. This model takes into account the elastic response of the bulk material (substrate) underneath the irradiated layer. The measured elastic strain is then the sum of a free strain due to the formation of radiation-induced defects and of an additional strain arising from the substrate elastic reaction. Application of this model allowed the calculation of the different strain contributions and the stress experienced by the irradiated layer. It is shown that these parameters may reach large values (respectively 0.7% and -1.9 GPa) despite the low radiation damage level.

  7. Response of Pt-based Bulk Metallic Glass to Shock Wave Compression

    NASA Astrophysics Data System (ADS)

    Lalone, B. M.; Gupta, Y. M.

    2009-06-01

    Plate impact experiments were performed on platinum based bulk metallic glass (BMG) samples having a nominal composition of Pt57.5Cu14.7Ni5.3P22.5, a material previously reported to support large plastic strains under quasi-static, uniaxial stress loading (J. Schroers, and W. L. Johnson, Phys. Rev. Lett. 93, 255506 (2004)). In the present shock wave experiments, peak longitudinal stresses ranged from 9-30 GPa. Piezoelectric pins and a velocity interferometer were used to measure shock velocities and particle velocity histories. A clear two-wave structure was observed in the particle velocity histories indicating an elastic-plastic response. The elastic wave amplitude was dependent on peak stress and sample thickness, with values ranging from 8.6 - 14.2 GPa. Measured wave profiles were converted to stress-density compression, and a nonlinear elastic model was fit to the measured elastic response. Unlike the quasi-static, uniaxial stress data on the same alloy, the shock wave, uniaxial strain results show a loss of strength above the elastic limit. Reasons for this strength loss are discussed. Work supported by the DOE.

  8. 49 CFR 172.514 - Bulk packagings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Bulk packagings. 172.514 Section 172.514... SECURITY PLANS Placarding § 172.514 Bulk packagings. (a) Except as provided in paragraph (c) of this section, each person who offers for transportation a bulk packaging which contains a hazardous...

  9. 49 CFR 172.514 - Bulk packagings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Bulk packagings. 172.514 Section 172.514... SECURITY PLANS Placarding § 172.514 Bulk packagings. (a) Except as provided in paragraph (c) of this section, each person who offers for transportation a bulk packaging which contains a hazardous...

  10. 49 CFR 172.514 - Bulk packagings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Bulk packagings. 172.514 Section 172.514... SECURITY PLANS Placarding § 172.514 Bulk packagings. (a) Except as provided in paragraph (c) of this section, each person who offers for transportation a bulk packaging which contains a hazardous...

  11. 49 CFR 172.514 - Bulk packagings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Bulk packagings. 172.514 Section 172.514... SECURITY PLANS Placarding § 172.514 Bulk packagings. (a) Except as provided in paragraph (c) of this section, each person who offers for transportation a bulk packaging which contains a hazardous...

  12. 49 CFR 172.514 - Bulk packagings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Bulk packagings. 172.514 Section 172.514... SECURITY PLANS Placarding § 172.514 Bulk packagings. (a) Except as provided in paragraph (c) of this section, each person who offers for transportation a bulk packaging which contains a hazardous...

  13. Strain localisation in two-phase materials: Insights from centimetre-scale numerical models and laboratory experiments with ice mixtures

    NASA Astrophysics Data System (ADS)

    Brune, S.; Czaplinska, D.; Piazolo, S.; Wilson, C. J. L.; Quinteros, J.

    2015-12-01

    Most numerical models of lithosphere deformation approximate the rheological behavior of polymineralic crust and mantle via single-phase flow laws assuming that the weakest or most abundant material controls the bulk rheology. However, previous work showed that in two phase aggregates the bulk viscosity of the dominant phase is significantly affected by second phase particles. Here we combine two unconventional approaches to quantify the relative impact of such particles on strain localisation and bulk response: (1) We run centimetre-scale numerical models of a matrix with inclusions using the elasto-visco-plastic FEM software Slim3D. Recrystallization-induced weakening processes in the matrix, i.e. grain boundary migration and nucleation, are approximated using strain-dependent viscous softening. (2) We conduct high T, constant strain rate deformation experiments with a matrix of deuterated ice (D2O) containing rigid or soft particles, i.e. calcite and graphite, respectively. Ice is a valuable rock analogue, as it replicates the microstructural and fabric changes as well as the non-Newtonian response of other anisotropic minerals, such as olivine and quartz. The laboratory experiments exhibit two types of rheological behaviour: stress partitioning between ice and particles and strain localization in rheologically softer material. To quantify the contribution of both response types, we calibrate numerical simulations with data derived from laboratory experiments. The strain rate, stress, and viscosity evolution of the numerical experiment provides insight to non-linear strain localization processes, particle motion and time-dependent stress concentrations during the deformation. We fit the parameters of the viscous softening function and thereby quantify the amount of additional weakening in the matrix of ice mixtures in comparison to pure ice, which allows to constrain softening parameters used in large-scale simulations of glacial flow and lithosphere deformation.

  14. 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

  15. Prediction of the Viscoelastic Bulk Modulus

    NASA Astrophysics Data System (ADS)

    Guo, Jiaxi; Simon, Sindee

    2010-03-01

    The bulk and shear viscoelastic responses for several materials appear to arise from the same molecular mechanisms at short times, i.e., Andrade creep where the KWW beta parameter is approximately 0.3. If this is indeed the case, prediction and placement of the bulk viscoelastic response can be made simply by knowing the limiting elastic and rubbery bulk moduli and the viscoelastic shear response. The proposed methodology, which uses only easily measured functions, is considerably less time- and labor-intensive than direct measurement of the viscoelastic bulk modulus. Here we investigate this hypothesis and compare the calculated viscoelastic bulk responses for several materials to existing data in the literature.

  16. Molecular identification and thermoresistance to boiling of Nocardia farcinica and Nocardia cyriacigeorgica from bovine bulk tank milk

    PubMed Central

    Condas, L.A.Z.; Ribeiro, M.G.; Gonoi, T.; Matsuzawa, T.; Yazawa, K.; Motta, R.G.; Franco, M.M.J.; Listoni, F.J.P.

    2012-01-01

    Two strains of Nocardia spp. were isolated from bovine milk of two individual bulk tank. Molecular identification classified the strains as Nocardia farcinica and Nocardia cyriacigeorgica. The thermorresistance to boiling of the isolates was carried out and was observed bacterial growth after boiling. Our findings indicate the potential risk of pathogen transmission to humans through contaminated milk with Nocardia spp. PMID:24031926

  17. Elastic Moduli Inheritance and Weakest Link in Bulk Metallic Glasses

    SciTech Connect

    Stoica, Alexandru Dan; Wang, Xun-Li; Lu, Z.P.; Clausen, Bjorn; Brown, Donald

    2012-01-01

    We show that a variety of bulk metallic glasses (BMGs) inherit their Young s modulus and shear modulus from the solvent components. This is attributed to preferential straining of locally solvent-rich configurations among tightly bonded atomic clusters, which constitute the weakest link in an amorphous structure. This aspect of inhomogeneous deformation, also revealed by our in-situ neutron diffraction studies of an elastically deformed BMG, suggests a scenario of rubber-like viscoelasticity owing to a hierarchy of atomic bonds in BMGs.

  18. Processing of bulk metallic glass.

    PubMed

    Schroers, Jan

    2010-04-12

    Bulk metallic glass (BMG) formers are multicomponent alloys that vitrify with remarkable ease during solidification. Technological interest in these materials has been generated by their unique properties, which often surpass those of conventional structural materials. The metastable nature of BMGs, however, has imposed a barrier to broad commercial adoption, particularly where the processing requirements of these alloys conflict with conventional metal processing methods. Research on the crystallization of BMG formers has uncovered novel thermoplastic forming (TPF)-based processing opportunities. Unique among metal processing methods, TPF utilizes the dramatic softening exhibited by a BMG as it approaches its glass-transition temperature and decouples the rapid cooling required to form a glass from the forming step. This article reviews crystallization processes in BMG former and summarizes and compares TPF-based processing methods. Finally, an assessment of scientific and technological advancements required for broader commercial utilization of BMGs will be made. PMID:20496386

  19. Isotopic signatures by bulk analyses

    SciTech Connect

    Efurd, D.W.; Rokop, D.J.

    1997-12-01

    Los Alamos National Laboratory has developed a series of measurement techniques for identification of nuclear signatures by analyzing bulk samples. Two specific applications for isotopic fingerprinting to identify the origin of anthropogenic radioactivity in bulk samples are presented. The first example is the analyses of environmental samples collected in the US Arctic to determine the impact of dumping of radionuclides in this polar region. Analyses of sediment and biota samples indicate that for the areas sampled the anthropogenic radionuclide content of sediments was predominantly the result of the deposition of global fallout. The anthropogenic radionuclide concentrations in fish, birds and mammals were very low. It can be surmised that marine food chains are presently not significantly affected. The second example is isotopic fingerprinting of water and sediment samples from the Rocky Flats Facility (RFP). The largest source of anthropogenic radioactivity presently affecting surface-waters at RFP is the sediments that are currently residing in the holding ponds. One gram of sediment from a holding pond contains approximately 50 times more plutonium than 1 liter of water from the pond. Essentially 100% of the uranium in Ponds A-1 and A-2 originated as depleted uranium. The largest source of radioactivity in the terminal Ponds A-4, B-5 and C-2 was naturally occurring uranium and its decay product radium. The uranium concentrations in the waters collected from the terminal ponds contained 0.05% or less of the interim standard calculated derived concentration guide for uranium in waters available to the public. All of the radioactivity observed in soil, sediment and water samples collected at RFP was naturally occurring, the result of processes at RFP or the result of global fallout. No extraneous anthropogenic alpha, beta or gamma activities were detected. The plutonium concentrations in Pond C-2 appear to vary seasonally.

  20. The influence of bi-metal interfaces on deformation mechanisms in bulk nanolaminar composites

    SciTech Connect

    Mara, Nathan Allan; Ledonne, Jon; Wynn, Thomas A; Rollett, Anthony D; Beyerlein, I. J.; Misra, Amit

    2011-01-04

    In this presentation, we report on the plastic deformation mechanisms in Ag-Cu and Cu-Nb nanocomposites rolled to large reductions. Starting with an Ag-Cu alloy with eutectic lamellar bilayer thickness of 200 nm, we roll the as-cast rods from 9.5 mm diameter to sheets of final thickness varying from 2.4 mm to 500 {micro}m, corresponding to 75% to 95% nominal reduction in thickness. Cu(111) X-ray pole figures of the rolled nanocomposites indicate a measured texture similar to that of Ag but different from that expected during rolling of pure bulk Cu involving dislocation slip alone. Visco-Plastic Self Consistent (VPSC) polycrystal modeling indicate that both silver and copper deformed by slip and twinning and the twin fraction reached over 30%, depending on rolling reduction. Because pure Cu is not expected to twin under these processing conditions, we hypothesize that twinning in Cu is induced by twinning in Ag, aided by the presence of high Ag-Cu interfacial content. Molecular Dynamics (MD) simulations are then carried out on perfect and defective Ag-Cu interfaces and the results support this hypothesis. In the Cu-Nb system, it has been found that at individual layer thicknesses of 40 nm and above, physical vapor deposited foils can be rolled to large strains. However, when the layer thickness decreases to {approx}5nm, shear instability during rolling limits ductility. In this work, we show the effects of cladding 5nm CuINb multilayers with 40 nm CuINb multilayers to limit the onset of geometric instability, thereby facilitating the deformation of 5nm Cu/Nb multi layers to large rolling strains. Results will be discussed in terms of the effects of the interface on deformation processes at diminishing length scales.

  1. Extensional Flow of Bulk Polymers

    NASA Technical Reports Server (NTRS)

    Peng, T. J.

    1972-01-01

    A study was made of the behavior of polyisobutylene under motion at a constant stretch history for both strip biaxial extensional flow and simple extensional flow. Steady-state non-Newtonian viscosities were observed at various constant stretch histories. Newtonian viscosities for both strip biaxial and simple extensional flow were found to be in agreement with the classical theory. The results of the study provide an essential part of the experimental background necessary for the development of a new general stress-strain-time relation for uncrosslinked and lightly crosslinked polymers.

  2. Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide.

    PubMed

    Li, Man-Rong; Retuerto, Maria; Stephens, Peter W; Croft, Mark; Sheptyakov, Denis; Pomjakushin, Vladimir; Deng, Zheng; Akamatsu, Hirofumi; Gopalan, Venkatraman; Sánchez-Benítez, Javier; Saouma, Felix O; Jang, Joon I; Walker, David; Greenblatt, Martha

    2016-08-16

    Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic-scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also high pressure in bulk oxide materials. Herein, we present the cationic rearrangement in bulk Mn2 FeMoO6 at unparalleled low temperatures of 150-300 (o) C. The irreversible ionic motion at ambient pressure, as evidenced by real-time powder synchrotron X-ray and neutron diffraction, and second harmonic generation, leads to a transition from a Ni3 TeO6 -type to an ordered-ilmenite structure, and dramatic changes of the electrical and magnetic properties. This work demonstrates a remarkable cationic rearrangement, with corresponding large changes in the physical properties in a bulk oxide at unprecedented low temperatures. PMID:27203790

  3. Cosmic Bulk Flow and the Local Motion from Cosmicflows-2

    NASA Astrophysics Data System (ADS)

    Courtois, Helene M.; Hoffman, Yehuda; Tully, R. Brent

    2015-08-01

    Full sky surveys of peculiar velocity are arguably the best way to map the large scale structure out to distances of a few times 100 Mpc/h.Using the largest and most accurate ever catalog of galaxy peculiar velocities Cosmicflows-2, the large scale structure has been reconstructed by means of the Wiener filter and constrained realizations assuming as a Bayesian prior model the LCDM standard model of cosmology. The present paper focuses on studying the bulk flow of the local flow field, defined as the mean velocity of top-hat spheres with radii ranging out to R=500 Mpc/h. Our main results is that the estimated bulk flow is consistent with the LCDM model with the WMAP inferred cosmological parameters. At R=50 (150)Mpc/h the estimated bulk velocity is 250 +/- 21 (239 +/- 38) km/s. The corresponding cosmic variance at these radii is 126 (60) km/s, which implies that these estimated bulk flows are dominated by the data and not by the assumed prior model. The estimated bulk velocity is dominated by the data out to R ˜200 Mpc/h, where the cosmic variance on the individual Supergalactic Cartesian components (of the r.m.s. values) exceeds the variance of the constrined realizations by at least a factor of 2. The SGX and SGY components of the CMB dipole velocity are recovered by the Wiener Filter velocity field down to a very few km/s. The SGZ component of the estimated velocity, the one that is most affected by the Zone of Avoidance, is off by 126km/s (an almost 2 sigma discrepancy).The bulk velocity analysis reported here is virtually unaffected by the Malmquist bias and very similar results are obtained for the data with and without the bias correction.

  4. Hybrid surface roughening modes during low-temperature heteroepitaxy: Growth of fully-strained metastable Ge1-xSnx alloys on Ge(001)2×1

    NASA Astrophysics Data System (ADS)

    Desjardins, P.; Spila, T.; Gürdal, O.; Taylor, N.; Greene, J. E.

    1999-12-01

    Fully-strained single-crystal metastable Ge1-xSnx alloys were grown on Ge(001) up to their critical epitaxial thickness values tepi(x) in order to probe surface roughening pathways leading to heteroepitaxial breakdown during low-temperature molecular-beam epitaxy under large compressive strain. All films with x>0.09 have comparable roughnesses while films with x<0.09 are considerably rougher with larger lateral feature sizes. Roughening rates increase with increasing x for films with x>0.09 due to a new hybrid relaxation path which only becomes accessible under high strain as kinetic roughening provides surface oscillations on lateral length scales that allow bulk relaxation through strain-induced islanding at growth temperatures where it could not otherwise proceed.

  5. Growth and properties of strained VOx thin films with controlled stoichiometry

    NASA Astrophysics Data System (ADS)

    Rata, A. D.; Chezan, A. R.; Haverkort, M. W.; Hsieh, H. H.; Lin, H.-J.; Chen, C. T.; Tjeng, L. H.; Hibma, T.

    2004-02-01

    We have succeeded in growing epitaxial films of rocksalt VOx on MgO(001) substrates. The oxygen content as a function of oxygen flux was determined using 18O2-Rutherford backscattering spectrometry and the vanadium valence using x-ray-absorption spectroscopy. The upper and lower stoichiometry limits found are similar to those known for bulk material (0.8large number of vacancies for both vanadium and oxygen were deduced, i.e., ≈16% for stoichiometric VO. These numbers are, surprisingly, very similar to those for bulk material and consequently quite strain insensitive. X-ray-absorption spectroscopy measurements reveal that the vacancies give rise to strong non-cubic crystal field effects. The electrical conductivity of the films is much lower than the conductivity of bulk samples, which we attribute to a decrease in the direct overlap between t2g orbitals in the coherently strained layers. The temperature dependence of the conductivity is consistent with a variable range hopping mechanism.

  6. Theory of bonding, strain, and segregation in germanium-carbon alloys

    NASA Astrophysics Data System (ADS)

    Kelires, P. C.

    1999-10-01

    We investigate the bulk and surface structure of Ge1-xCx alloys using Monte Carlo simulations in the semigrand canonical ensemble, within the empirical potential formalism. We consider free-floating alloys as well as epitaxial alloys on Si and Ge substrates. The lattice constants as a function of carbon content are calculated and fitted to quadratic expressions for easy reference. Large deviations (negative bowing) from Vegard's law are found. We confirm the presence of Ge-C bonds and thus of substitutional carbon in the bulk of the material, for both epitaxial conditions. The most probable bulk carbon-carbon configurations are in a third-nearest-neighbor arrangement. The surface structure of alloys strained on Ge is characterized by strong segregation of carbon to the top layers. Segregation is less effective in alloys strained on Si. Most probable dimer configurations are both C-C and Ge-C dimers, for low carbon contents and Ge-substrate conditions, and Ge-C dimers for higher carbon contents and both epitaxial conditions.

  7. A study of the effect of apparent strain on thermal stress measurement for two types of elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.

    1983-01-01

    A weldable type strain gage was used to measure low level thermal stress in an elevated temperature environment. Foil strain gages used in a comparative manner reveal that the apparent strain of weldable strain gages is not sufficiently known to acquire accurate low level thermal stress data. Apparent strain data acquired from coupon tests reveals a large scatter in apparent strain characteristics among the weldable strain gages. It is concluded that apparent strain data for individual weldable strain gages must be required prior to installation if valid thermal stress data is to be obtained through the temperature range of room temperature to 755 K (900 F).

  8. Synthesis of Giant Zeolite Crystals by a Bulk-Material Dissolution Technique.

    PubMed

    Shimizu; Hamada

    1999-09-01

    Using a quartz glass tube as a bulk silica source under aqueous hydrothermal conditions afforded giant crystals of MFI zeolite about 3 mm in size (see photo). Similar procedures were successfully applied to bulk aluminosilicate ceramics to synthesize large crystals of other zeolites, such as ANA, JBW, CAN, and SOD. PMID:10508361

  9. Dislocation mean free paths and strain hardening of crystals.

    PubMed

    Devincre, B; Hoc, T; Kubin, L

    2008-06-27

    Predicting the strain hardening properties of crystals constitutes a long-standing challenge for dislocation theory. The main difficulty resides in the integration of dislocation processes through a wide range of time and length scales, up to macroscopic dimensions. In the present multiscale approach, dislocation dynamics simulations are used to establish a dislocation-based continuum model incorporating discrete and intermittent aspects of plastic flow. This is performed through the modeling of a key quantity, the mean free path of dislocations. The model is then integrated at the scale of bulk crystals, which allows for the detailed reproduction of the complex deformation curves of face-centered cubic crystals. Because of its predictive ability, the proposed framework has a large potential for further applications. PMID:18583605

  10. Aspects of silicon bulk lifetimes

    NASA Technical Reports Server (NTRS)

    Landsberg, P. T.

    1985-01-01

    The best lifetimes attained for bulk crytalline silicon as a function of doping concentrations are analyzed. It is assumed that the dopants which set the Fermi level do not contribute to the recombination traffic which is due to the unknown defect. This defect is assumed to have two charge states: neutral and negative, the neutral defect concentration is frozen-in at some temperature T sub f. The higher doping concentrations should include the band-band Auger effect by using a generalization of the Shockley-Read-Hall (SRH) mechanism. The generalization of the SRH mechanism is discussed. This formulation gives a straightforward procedure for incorporating both band-band and band-trap Auger effects in the SRH procedure. Two related questions arise in this context: (1) it may sometimes be useful to write the steady-state occupation probability of the traps implied by SRH procedure in a form which approximates to the Fermi-Dirac distribution; and (2) the effect on the SRH mechanism of spreading N sub t levels at one energy uniformly over a range of energies is discussed.

  11. Covalent bulk functionalization of graphene.

    PubMed

    Englert, Jan M; Dotzer, Christoph; Yang, Guang; Schmid, Martin; Papp, Christian; Gottfried, J Michael; Steinrück, Hans-Peter; Spiecker, Erdmann; Hauke, Frank; Hirsch, Andreas

    2011-04-01

    Graphene, a truly two-dimensional and fully π-conjugated honeycomb carbon network, is currently evolving into the most promising successor to silicon in micro- and nanoelectronic applications. However, its wider application is impeded by the difficulties in opening a bandgap in its gapless band-structure, as well as the lack of processability in the resultant intrinscially insoluble material. Covalent chemical modification of the π-electron system is capable of addressing both of these issues through the introduction of variable chemical decoration. Although there has been significant research activity in the field of functionalized graphene, most work to date has focused on the use of graphene oxide. In this Article, we report on the first wet chemical bulk functionalization route beginning with pristine graphite that does not require initial oxidative damage of the graphene basal planes. Through effective reductive activation, covalent functionalization of the charged graphene is achieved by organic diazonium salts. Functionalization was observed spectroscopically, and successfully prevents reaggregation while providing solubility in common organic media. PMID:21430685

  12. A treatment plant receiving waste water from multiple bulk drug manufacturers is a reservoir for highly multi-drug resistant integron-bearing bacteria.

    PubMed

    Marathe, Nachiket P; Regina, Viduthalai R; Walujkar, Sandeep A; Charan, Shakti Singh; Moore, Edward R B; Larsson, D G Joakim; Shouche, Yogesh S

    2013-01-01

    The arenas and detailed mechanisms for transfer of antibiotic resistance genes between environmental bacteria and pathogens are largely unclear. Selection pressures from antibiotics in situations where environmental bacteria and human pathogens meet are expected to increase the risks for such gene transfer events. We hypothesize that waste-water treatment plants (WWTPs) serving antibiotic manufacturing industries may provide such spawning grounds, given the high bacterial densities present there together with exceptionally strong and persistent selection pressures from the antibiotic-contaminated waste. Previous analyses of effluent from an Indian industrial WWTP that processes waste from bulk drug production revealed the presence of a range of drugs, including broad spectrum antibiotics at extremely high concentrations (mg/L range). In this study, we have characterized the antibiotic resistance profiles of 93 bacterial strains sampled at different stages of the treatment process from the WWTP against 39 antibiotics belonging to 12 different classes. A large majority (86%) of the strains were resistant to 20 or more antibiotics. Although there were no classically-recognized human pathogens among the 93 isolated strains, opportunistic pathogens such as Ochrobactrum intermedium, Providencia rettgeri, vancomycin resistant Enterococci (VRE), Aerococcus sp. and Citrobacter freundii were found to be highly resistant. One of the O. intermedium strains (ER1) was resistant to 36 antibiotics, while P. rettgeri (OSR3) was resistant to 35 antibiotics. Class 1 and 2 integrons were detected in 74/93 (80%) strains each, and 88/93 (95%) strains harbored at least one type of integron. The qPCR analysis of community DNA also showed an unprecedented high prevalence of integrons, suggesting that the bacteria living under such high selective pressure have an appreciable potential for genetic exchange of resistance genes via mobile gene cassettes. The present study provides insight into

  13. A Treatment Plant Receiving Waste Water from Multiple Bulk Drug Manufacturers Is a Reservoir for Highly Multi-Drug Resistant Integron-Bearing Bacteria

    PubMed Central

    Walujkar, Sandeep A.; Charan, Shakti Singh; Moore, Edward R. B.; Larsson, D. G. Joakim; Shouche, Yogesh S.

    2013-01-01

    The arenas and detailed mechanisms for transfer of antibiotic resistance genes between environmental bacteria and pathogens are largely unclear. Selection pressures from antibiotics in situations where environmental bacteria and human pathogens meet are expected to increase the risks for such gene transfer events. We hypothesize that waste-water treatment plants (WWTPs) serving antibiotic manufacturing industries may provide such spawning grounds, given the high bacterial densities present there together with exceptionally strong and persistent selection pressures from the antibiotic-contaminated waste. Previous analyses of effluent from an Indian industrial WWTP that processes waste from bulk drug production revealed the presence of a range of drugs, including broad spectrum antibiotics at extremely high concentrations (mg/L range). In this study, we have characterized the antibiotic resistance profiles of 93 bacterial strains sampled at different stages of the treatment process from the WWTP against 39 antibiotics belonging to 12 different classes. A large majority (86%) of the strains were resistant to 20 or more antibiotics. Although there were no classically-recognized human pathogens among the 93 isolated strains, opportunistic pathogens such as Ochrobactrum intermedium, Providencia rettgeri, vancomycin resistant Enterococci (VRE), Aerococcus sp. and Citrobacter freundii were found to be highly resistant. One of the O. intermedium strains (ER1) was resistant to 36 antibiotics, while P. rettgeri (OSR3) was resistant to 35 antibiotics. Class 1 and 2 integrons were detected in 74/93 (80%) strains each, and 88/93 (95%) strains harbored at least one type of integron. The qPCR analysis of community DNA also showed an unprecedented high prevalence of integrons, suggesting that the bacteria living under such high selective pressure have an appreciable potential for genetic exchange of resistance genes via mobile gene cassettes. The present study provides insight into

  14. Influence of object concentration on finite strain and effective viscosity contrast: insights from naturally deformed packstones

    NASA Astrophysics Data System (ADS)

    Vitale, Stefano; Mazzoli, Stefano

    Deformed conglomerates and ooidal/oncoidal packstones are commonly used to evaluate finite strain in deformed sedimentary successions. In order to obtain a correct estimate of finite strain, it is necessary to consider not only the different behaviour of matrix and objects, but also object concentration. The analysis of two-component rocks characterised by high values of packing commonly results in a substantial underestimate of bulk strain and of viscosity contrast between objects and matrix. In this study, the effects of the volumetric fraction of competent inclusions on both object and bulk measured finite strain, as well as on apparent viscosity contrast, have been investigated in naturally deformed packstones characterised by variable object concentration on the scale of the hand specimen (and hence for homogenous viscosity contrast). Object finite strain has been obtained by Rf/ ϕ analysis, whereas the Fry method provides a measure of whole-rock strain that is also a function of inclusion concentration. Therefore, the finite strain measured by the Fry method is better termed effective bulk strain. In order to investigate the role of object concentration, this parameter has been plotted against object and effective bulk strain, and also against viscosity contrast. These diagrams show that: (i) for high values of packing, measured object and effective bulk strain show values that are significantly lower with respect to the calculated maximum value (that would result in the ideal case of no particle interaction and represents therefore the real bulk strain of the samples); (ii) the viscosity contrast shows lower values with respect to the calculated maximum one (that is equal for the three principal sections of the finite strain ellipsoid), and as packing reaches the maximum value, the viscosity contrast approaches a unit value. Empirical equations have also been found that link object concentration with both object and effective bulk finite strain.

  15. Bulk entanglement spectrum in gapped spin ladders

    NASA Astrophysics Data System (ADS)

    Santos, Raul A.; Jian, Chao-Ming; Lundgren, Rex

    2016-06-01

    We study the bulk entanglement of a series of gapped ground states of spin ladders, representative of the Haldane phase. These ground states of spin S /2 ladders generalize the valence bond solid ground state. In the case of spin 1/2 ladders, we study a generalization of the Affleck-Kennedy-Lieb-Tasaki and Nersesyan-Tsvelik states and fully characterize the bulk entanglement Hamiltonian. In the case of general spin S , we argue that in the Haldane phase the bulk entanglement spectrum of a half-integer ladder is either gapless or possess a degenerate ground state. For ladders with integer valued spin particles, the generic bulk entanglement spectrum should have an entanglement gap. Finally, we give an example of a series of trivial states of higher spin S >1 in which the bulk entanglement Hamiltonian is critical, signaling that the relation between topological states and a critical bulk entanglement Hamiltonian is not unique to topological systems.

  16. DETECTION AND FATE OF BACILLUS ANTHRACIS (STERNE) VEGETATIVE CELLS AND SPORES ADDED TO BULK TANK MILK

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A preparation of spores of Bacillus anthracis (Sterne strain) was utilized to evaluate commercially available reagents and portable equipment for detecting anthrax contamination using real time PCR and to assess the fate of spores added directly to bulk tank milk. The Ruggedized Automated Pathogen ...

  17. Relative entropy equals bulk relative entropy

    NASA Astrophysics Data System (ADS)

    Jafferis, Daniel L.; Lewkowycz, Aitor; Maldacena, Juan; Suh, S. Josephine

    2016-06-01

    We consider the gravity dual of the modular Hamiltonian associated to a general subregion of a boundary theory. We use it to argue that the relative entropy of nearby states is given by the relative entropy in the bulk, to leading order in the bulk gravitational coupling. We also argue that the boundary modular flow is dual to the bulk modular flow in the entanglement wedge, with implications for entanglement wedge reconstruction.

  18. Effect of rare earth substitution in cobalt ferrite bulk materials

    NASA Astrophysics Data System (ADS)

    Bulai, G.; Diamandescu, L.; Dumitru, I.; Gurlui, S.; Feder, M.; Caltun, O. F.

    2015-09-01

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm-3 decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe2O4 sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples.

  19. Aqueous Alteration and Martian Bulk Chemical Composition

    NASA Astrophysics Data System (ADS)

    Taylor, J.; Boynton, W. V.; McLennan, S. M.

    2009-12-01

    The bulk compositions of the terrestrial planets are fundamentally important in testing models for planetary accretion. This is particularly true for the abundances of volatile elements. In the absence of direct samples of the mantle, we must rely on samples of surface materials obtained from orbit (specifically from the Mars Odyssey Gamma-Ray Spectrometer, GRS), Martian meteorites, and in situ analyses. Use of these databases requires understanding the processes that formed and modified the igneous rocks composing the crust; aqueous processes are particularly important. Halogens are useful elements for understanding Martian bulk composition and surface aqueous alteration. Here, we focus on Cl, which is an incompatible element during partial melting. Cosmochemically, Cl is a moderately volatile element with a condensation temperature of 948 Kelvin, only slightly below that of K (1006 Kelvin), another incompatible lithophile element. Cl is substantially lost during magma degassing at or near the surface, making it difficult to determine its abundances in the interior through analyses of rocks, leading to an underestimate of Cl abundance in bulk silicate Mars. GRS data for Mars between approximately 52 degrees north and south show that K and Cl are uncorrelated. This is not surprising as they fractionate easily by release of Cl-bearing gases from magmas near the surface and during eruptions, by aqueous alteration of surface materials, and by the large solubility of Cl salts in water. A positive correlation of Cl with H supports the role of water in Cl redistribution. In spite of the lack of correlation between K and Cl, the mean Cl/K ratio is roughly chondritic: 1.5 ±0.1 compared to 1.28 in CI chondrites. However, Cl appears to be enriched at least in the uppermost few tens of cm analyzed by the GRS: Cl correlates with both H and S, but a linear fit to the data shows a positive Cl intercept of about 0.3, which suggests a decoupling of Cl from S and H. Adjusting the

  20. Characterization of Gram-negative psychrotrophic bacteria isolated from Italian bulk tank milk.

    PubMed

    Decimo, Marilù; Morandi, Stefano; Silvetti, Tiziana; Brasca, Milena

    2014-10-01

    Eighty psychrotrophic bacterial strains, isolated from different northwest Italian bulk tank milks destined for Grana Padano cheese production, were identified by 16S rRNA gene amplification and partial sequence analysis of the rpoB gene. Pseudomonas spp. were the most commonly occurring contaminants, P. fluorescens being the predominant isolated species, along with Enterobacteriaceae, primarily Serratia marcescens. RAPD-PCR was used to study genetic variability and distinguish closely related strains; a high degree of genetic heterogeneity among the strains was highlighted. All the strains were characterized for their ability to produce proteases, lipases and lecithinases at different temperatures (7, 22, and 30 °C). Forty-one of the psychrotrophic strains were positive for all the enzymatic activities. The highest number of positive strains for all the incubation temperatures was found for lipolytic activity (59), followed by proteolytic (31) and lecithinase (28) activities, and the enzymatic traits varied among the Pseudomonas and Enterobacteriaceae strains. The proteolytic psychrotrophic strains were screened for the presence of the aprX gene, coding for a heat-resistant metalloprotease in Pseudomonas spp. The aprX gene was detected in 19 of 63 Pseudomonas strains, and was widespread in the P. fluorescens strains (14/19). PRATICAL APPLICATION: The study provides new data on the enzymatic activity of Gram-negative psychrotrophic bacteria, useful in developing strategies to control the proteo-lipolytic spoilage of raw and processed milk that causes gelation, off-flavors, and loss of sensory quality and shelf life. PMID:25224662

  1. Understanding strain-induced phase transformations in BiFeO3 thin films

    SciTech Connect

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

    2015-05-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO₃ thin films, which comprises a tetragonal-like (T´) and an intermediate S´ polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T´ phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S´ phase is energetically very close to the T´ phase, but is structurally similar to the bulk rhombohedral (R) phase. By fully characterizing the intermediate S´ polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T´ and S´ phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S´ and T´ polymorphs, which have very different octahedral rotation patterns and c/a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO3 films. Additionally, a blueshift in the band gap when moving from R to S´ to T´ is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

  2. Understanding strain-induced phase transformations in BiFeO3 thin films

    DOE PAGESBeta

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

    2015-05-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO₃ thin films, which comprises a tetragonal-like (T´) and an intermediate S´ polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T´ phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S´ phase is energetically very close to the T´ phase, but is structurally similar to the bulk rhombohedral (R) phase. By fully characterizing the intermediate S´ polymorph, it is demonstrated that the flat energy landscape resultingmore » in the absence of an energy barrier between the T´ and S´ phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S´ and T´ polymorphs, which have very different octahedral rotation patterns and c/a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO3 films. Additionally, a blueshift in the band gap when moving from R to S´ to T´ is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.« less

  3. 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.

  4. 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.

  5. Strain Engineering of Transition Metal Dichalcogenides

    NASA Astrophysics Data System (ADS)

    Dadgar, Ali; Pasupathy, Abhay; Herman, Irving; Wang, Dennis; Kang, Kyungnam; Yang, Eui-Hyeok

    The application of strain to materials can cause changes to bandwidth, effective masses, degeneracies and even structural phases. In the case of the transition metal dichalcogenide (TMD) semiconductors, small strain (around 1 percent) is expected to change band gaps and mobilities, while larger strains are expected to cause phase changes from the triangular 2H phase to orthorhombic 1T' phases. We will describe experimental techniques to apply small and large (around 10 percent) strains to one or few layer samples of the TMD semiconductors, and describe the effect of the strain using optical (Raman, photoluminescence) and cryogenic transport techniques.

  6. Strain rate change tests with the Split Hopkinson Bar method

    NASA Astrophysics Data System (ADS)

    Isakov, M.; Kokkonen, J.; Östman, K.; Kuokkala, V.-T.

    2016-05-01

    In this paper, methods to produce rapid strain rate changes for strain rate sensitivity measurements in Split Hopkinson Bar arrangements are presented and discussed. Two different cases are considered: a strain rate change test within the high strain rate region in compression, and a tension test incorporating a large strain rate jump directly from the low strain rate region to high strain rates. The former method is based on the loading wave amplitude manipulation, while the latter method is based on the incorporation of a low strain rate loading device into a Tensile Split Hopkinson Bar apparatus.

  7. Intercalation-driven reversible control of magnetism in bulk ferromagnets.

    PubMed

    Dasgupta, Subho; Das, Bijoy; Knapp, Michael; Brand, Richard A; Ehrenberg, Helmut; Kruk, Robert; Hahn, Horst

    2014-07-16

    An extension in magnetoelectric effects is proposed to include reversible chemistry-controlled magnetization variations. This ion-intercalation-driven magnetic control can be fully reversible and pertinent to bulk material volumes. The concept is demonstrated for ferromagnetic iron oxide where the intercalated lithium ions cause valence change and partial redistribution of Fe(3+) cations yielding a large and fully reversible change in magnetization at room temperature. PMID:24591165

  8. Hard and fragile holmium-based bulk metallic glasses

    SciTech Connect

    Luo, Q.; Zhao, D.Q.; Pan, M.X.; Wang, R.J.; Wang, W.H.

    2006-05-01

    A family of holmium-based bulk metallic glasses (BMGs) with high glass-forming ability is obtained. The Ho-based BMGs exhibit much larger elastic moduli and high thermal stability in contrast to other known rare-earth (RE)-based BMGs. In particular, the BMGs show a large value of fragility. It is expected that the hard RE-based glasses with high glass-forming ability and fragile behaviors make them the appropriate candidate for glass transition study.

  9. 27 CFR 20.191 - Bulk articles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of...

  10. 27 CFR 20.191 - Bulk articles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of...

  11. 27 CFR 20.191 - Bulk articles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of...

  12. Temporal soil bulk density following tillage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil is the medium for air, energy, water, and chemical transport between the atmosphere and the solid earth. Soil bulk density is a key variable impacting the rate at which this transport occurs. Typically, soil bulk density is measured by the gravimetric method, where a sample of known volume is t...

  13. 27 CFR 20.191 - Bulk articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of...

  14. 27 CFR 20.191 - Bulk articles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bulk articles. 20.191... Users of Specially Denatured Spirits Operations by Users § 20.191 Bulk articles. Users who convey articles in containers exceeding one gallon may provide the recipient with a photocopy of subpart G of...

  15. Bacterial Strain Diversity Within Wounds

    PubMed Central

    Kirkup, Benjamin C.

    2015-01-01

    Significance: Rare bacterial taxa (taxa of low relative frequency) are numerous and ubiquitous in virtually any sample—including wound samples. In addition, even the high-frequency genera and species contain multiple strains. These strains, individually, are each only a small fraction of the total bacterial population. Against the view that wounds contain relatively few kinds of bacteria, this newly recognized diversity implies a relatively high rate of migration into the wound and the potential for diversification during infection. Understanding the biological and medical importance of these numerous taxa is an important new element of wound microbiology. Recent Advances: Only recently have these numerous strains been discovered; the technology to detect, identify, and characterize them is still in its infancy. Multiple strains of both gram-negative and gram-positive bacteria have been found in a single wound. In the few cases studied, the distribution of the bacteria suggests microhabitats and biological interactions. Critical Issues: The distribution of the strains, their phenotypic diversity, and their interactions are still largely uncharacterized. The technologies to investigate this level of genomic detail are still developing and have not been largely deployed to investigate wounds. Future Directions: As advanced metagenomics, single-cell genomics, and advanced microscopy develop, the study of wound microbiology will better address the complex interplay of numerous individually rare strains with both the host and each other. PMID:25566411

  16. Role of epitaxial strain on the magnetic structure of Fe-doped CoFe2O4

    NASA Astrophysics Data System (ADS)

    Moyer, J. A.; Kumah, D. P.; Vaz, C. A. F.; Arena, D. A.; Henrich, V. E.

    2013-11-01

    The magnetic structure of Fe-doped CoFe2O4 (Co1-xFe2+xO4) grown on MgO (0 0 1) and SrTiO3 (0 0 1) substrates is studied with superconducting quantum interference device magnetometry and soft x-ray magnetic spectroscopies. X-ray and electron diffraction show that the choice of substrate has large effects on the strain, crystal structure and surface morphology of Co1-xFe2+xO4 thin films. Samples grown on MgO have small, coherent strains and surfaces that are nearly atomically flat, whereas films grown on SrTiO3 have large tensile strains and surfaces terminated with islands, which indicate the presence of a large density of misfit dislocations. These differences in structural properties correlate with the large differences seen in the magnetic structure; samples grown on SrTiO3 have larger magnetic moments and increased anisotropies compared to those grown on MgO. Most strikingly, the large magnetic spin and orbital moments found in the films grown on SrTiO3 suggest a suppression of anti-phase boundary formation, which we attribute to the large compressive lattice mismatch and the formation of misfit dislocations during the film growth in order to relieve the epitaxial strain. This results in the films grown on SrTiO3 having magnetic properties that are more similar to bulk Co1-xFe2+xO4 than those grown on MgO, demonstrating that epitaxial strain can result in large changes in the magnetic structure of Co1-xFe2+xO4.

  17. 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.

  18. 76 FR 8658 - Bulk Solid Hazardous Materials: Harmonization With the International Maritime Solid Bulk Cargoes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ...), 1974, as amended, that carry bulk solid cargoes other than grain. The final rule (75 FR 64586) allows... SECURITY Coast Guard 46 CFR Part 148 RIN 1625-AB47 Bulk Solid Hazardous Materials: Harmonization With the International Maritime Solid Bulk Cargoes (IMSBC) Code AGENCY: Coast Guard, DHS. ACTION: Rule;...

  19. 75 FR 34682 - Bulk Solid Hazardous Materials: Harmonization With the International Maritime Solid Bulk Cargoes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-18

    ... SECURITY Coast Guard 46 CFR Parts 97 and 148 RIN 1625-AB47 Bulk Solid Hazardous Materials: Harmonization With the International Maritime Solid Bulk Cargoes (IMSBC) Code; Correction AGENCY: Coast Guard, DHS... proposed rule published in the Federal Register on June 17, 2010, entitled ``Bulk Solid Hazardous...

  20. Bulk amorphous metallic alloys: Synthesis by fluxing techniques and properties

    SciTech Connect

    He, Yi; Shen, Tongde; Schwarz, R.B.

    1997-05-01

    Bulk amorphous alloys having dimensions of at least 1 cm diameter have been prepared in the Pd-Ni-P, Pd-Cu-P, Pd-Cu-Ni-P, and Pd-Ni-Fe-P systems using a fluxing and water quenching technique. The compositions for bulk glass formation have been determined in these systems. For these bulk metallic glasses, the difference between the crystallization temperature T{sub x}, and the glass transition temperature T{sub g}, {Delta}T = T{sub x} - T{sub g}, ranges from 60 to 1 10 K. These large values of {Delta}T open the possibility for the fabrication of amorphous near net-shape components using techniques such as injection molding. The thermal, elastic, and magnetic properties of these alloys have been studied, and we have found that bulk amorphous Pd{sub 40}Ni{sub 22.5}Fe{sub 17.5}P{sub 20} has spin glass behavior for temperatures below 30 K. 65 refs., 14 figs., 3 tabs.